Occupational Safety Training Document for the Leather, Feather, and Silk Industry

DOWNLOAD THE OCCUPATIONAL SAFETY DOCUMENT SET (6 GROUPS, MORE THAN 300 PROFESSIONS)

The document for the occupational safety training course in the leather, down feather, and silk industry helps workers equip themselves with safety knowledge and prevent hazards in the leather, down feather, and silk industry.

CHAPTER I: PRODUCTION AND PROCESSING SITUATION OF LEATHER, DOWN FEATHERS, SILK, AND DYEING WORK

I. PRODUCTION AND PROCESSING SITUATION OF LEATHER AND DOWN FEATHERS

1. What are down feathers? in the safety document for the leather, down feather, and silk industry

• Down feathers are the layer of feathers closest to the skin of bird species. This layer of super fine and light feathers can create small “air pockets,” keeping the body warm. Down feather is a general term for the feathers of waterfowl, birds, ducks, muscovy ducks, geese, etc. The composition includes down (plumules) and body feathers (contour feathers, flight feathers).
• Feathers are epidermal growths that form the distinctive outer covering, or plumage, of birds and some theropod dinosaurs. Feathers are considered the most complex integumentary structures found in vertebrates and are a prime example of a complex evolutionary novelty in nature. Feathers are one of the characteristics that distinguish existing bird species of the class Aves. Theropod dinosaurs also had feathers, hence they are also called feathered dinosaurs.
• Feathers are generally quite small, light, and silky smooth. Each feather can occupy a large volume of air, creating its characteristic insulating ability. With their light, porous structure and excellent heat retention, down feathers are a material often used to make jackets, puffer coats, or expensive bedding sets.
• Although feathers cover most parts of a bird’s body, they only grow on certain well-defined areas of the skin. Feathers assist birds in flight, provide insulation, waterproofing, and coloration that aids in communication and self-protection.

2. Applications in daily life in the safety document for the leather, down feather, and silk industry

With good heat retention, safety, and lightweight properties, down feather material is widely applied in various products and fields, especially in the fashion industry and the production of high-end bedding.

• Application in the production of bedding
  • This is a familiar product for every family made from down feather material. The heat retention of a down comforter is extremely good. Folding it for storage is also very convenient. Using products with down feather filling for bedding creates a perfectly cozy sleep, promoting deep and safe sleep for the user.

• Application in fashion
  • Down puffer jackets are also one of the typical products made from down feather material. This type of jacket provides excellent insulation and has a durability of up to 10 – 15 years. Down jackets are suitable for the climate of northern Vietnam and are convenient to bring when traveling to cold climates due to the material’s lightness and convenience.

• Analysis of the pros and cons of down feather material
  • Advantages of down feather material

• • Effective heat-balancing capability: The most wonderful advantage of down feather material is its ability to regulate temperature, which explains why it is so widely used in the fashion and bedding industries today.
  • Down feathers are only 1/3 the weight of conventional materials: Products made from down feathers such as jackets, blankets, and pillow inserts are very light. When using these products, we do not face any hassle. Because of its ultra-light characteristic, the comfort of down is the first thing we feel when we come into contact with this special material.
  • High safety: Down feathers are produced from natural materials, so no impurities adhere to them. Before being made into products like jackets, blankets, and pillows, the down feathers undergo a rigorous refining process to remove bacteria and deodorize any odors on the product so that no pathogens can grow in this material. Therefore, users can be completely assured when using products from down feather material.
• Disadvantages of down feathers
  • Scarcity, high price: Due to its high applicability, the world’s supply of down feathers is becoming increasingly scarce, with supply not meeting demand. The price of down is also quite expensive, so products using this material are not cheap.
  • Difficult to wash: Down feathers have high durability, but their quality can easily degrade when exposed to water, so special care must be taken during use to make the product last longer.

However, it is necessary to wash gently and use chemicals with low strong cleaning properties. After washing, only dry in the shade, do not dry directly under harsh sunlight to help the feathers not clump and reduce quality.

3. Production and processing situation of leather and down feathers in the safety document for the leather, down feather, and silk industry

• Since ancient times, garments made from natural fibers have been known and always favored. Through many periods, especially the 20th century with the remarkable development of science and technology, synthetic and artificial fabrics gradually dominated the market.
• This is because they met criteria such as quantity, durability, low cost, and variety. However, as living standards improved, consumers wanted to return to garments of natural origin because they have outstanding advantages that synthetic fibers find hard to meet, such as being light, porous, cool in summer, and warm in winter.
• They have good moisture absorption and release capabilities, and especially, they are environmentally friendly, biodegradable, resistant to mold, and block UV rays. Because they meet the needs of protecting users’ health as well as protecting the earth, the demand for environmentally friendly fabrics is growing, leading giant textile companies worldwide to increasingly want to assert their position in the textile field by increasing the production of “clean” fabrics from natural fibers.
• Natural fibers can be defined as “fibers created from plants (such as leaves, stems, bark or trees, fruits, seeds like cotton, hemp, hibiscus, flax, jute, bamboo, banana, coir, kapok, and algae), which can be easily converted into fiber form for textiles or used to produce many other types of materials.” The use of natural fibers to meet human needs dates back thousands of years and has always played an important role in life.
• In addition to fabrics like silk, wool, linen, and cotton, hemp fabric is also a type of fabric of natural origin, possessing superior properties such as being light, porous, cool, with good moisture absorption and release, and especially environmentally friendly, with mold resistance and UV protection. With its strong, resilient characteristics, requiring little water and not much care, hemp is a special plant. The fiber spun from hemp is the strongest natural fiber, even stronger than linen.
• For this reason, NIKE is currently using fabric woven from this breathable, antibacterial, and UV-resistant fiber as a material for shoe production. Ding (a representative of Nike) said: “We believe that organic cotton and hemp will be the mainstream direction in the future.” Vietnam has a tropical climate, hot in the summer and cold in the winter.
• Therefore, consumers always tend to choose fabrics with good sweat absorption and breathability. Capturing these consumer characteristics, the research team came up with the idea of researching the technology of weaving and finishing fabric from a hemp-viscose blend. In 2010, with the approval of the Ministry of Industry and Trade, the Textile Research Sub-Institute implemented the project “Research on weaving, dyeing, and finishing technology for apparel fabric from hemp-viscose blend yarn.” The hemp-viscose blend fabric adds diversity to the products of the Vietnamese textile industry, enhances its competitiveness, and meets the demand for fashionable apparel fabric for consumers.

---

II. SILK PROCESSING

1. What is silk? in the safety document for the leather, down feather, and silk industry

• Overview of Silk
  • Silk is a type of fiber produced by silkworms that feed on mulberry leaves. It is one of the most valuable natural fibers used as a raw material for the textile industry for a very long time, being a rare and much higher quality commodity compared to others.
  • Silk is the durable result of the cocoon-spinning process of mulberry-eating silkworms. Fibroin is the basic substance in silk, accounting for about 75% of its composition. Silk is the finest natural fiber, with a nearly triangular cross-section, giving it a high luster (cultivated silk has a higher luster than wild silk). Silk is usually white or cream-colored; wild silk can be brown, orange-yellow, or green. It is the strongest natural fiber, losing only 20% of its strength when wet, has moderate abrasion resistance, is lightweight, and wrinkles easily. Silk has excellent water absorption and moisture-wicking properties. Therefore, when wearing clothes made from silk, there will be no smell of sweat even if you wear them all day.
  • History of Sericulture: China was the first country in the world to cultivate mulberries and raise silkworms. Sericulture then developed and spread to other regions of the world. 4,000-5,000 years ago, the Chinese already knew how to raise and domesticate silkworms. The Chronicles mention sericulture during the reign of King Zhou (2200 BC). Silk at that time was reserved exclusively for royalty and nobles, symbolizing the people’s submission to the king. The secret of the silk industry was kept by the Chinese for a long time; it took nearly 1,000 years for this craft to be revealed and spread to neighboring countries via the Silk Road.
  • According to Western historians, mulberry trees were grown and developed in India via Tibet around 1400 BC, and the craft of sericulture began in the Ganges delta. According to Indian historians, the first place of silkworm rearing was in the Himalayan region. When the British came to India, the silk trade led to the development and spread of sericulture to other areas such as Mysore, Jammu, and Kashmir.
  • Arabia, by importing silkworm eggs and mulberry seeds from India, was also one of the early places to have sericulture.
  • In the 4th century, sericulture was established in India as the center of Asia, and silk was exported to Rome (Italy). But by the 6th century, the Romans had learned the art of silk production, and silk was produced in Europe, with the Romans completely dominating this field of production. From Italy, sericulture spread to Greece, Austria, and France.
  • In Austria, sericulture developed strongly in the 9th-11th centuries. In France, mulberry cultivation and silkworm rearing began in 1340. The French silk industry was established in the late 17th century and developed until the mid-18th century. In the 19th century, French sericulture was hit by the pebrine disease (Nosema), which spread to Europe and the Middle East, causing a crisis in the industry. In 1870, Louis Pasteur discovered that pebrine spores were the cause of the disease and he proposed a way to eliminate it, thus saving the silk industry from crisis, and it continues to expand and develop today. Due to its economic benefits, the silk industry is of interest to many countries.
• Types of Silkworms
  • There are 4 types of natural silk. The most produced type, accounting for 95% of the world’s production, is from the mulberry silkworm. Other types include Eri silk (from worms that eat castor or cassava leaves), Tussah silk, and Oak silk.
    • Mulberry Silkworm
      • Exploited by humans for over 4,000 years, the mulberry silkworm was later classified and its breeds identified with origins from Japan, China, Europe, and India based on geographical distribution. They are also named by voltinism: univoltine, bivoltine, multivoltine, or called purebreds, hybrids (single cross, double cross).
      • Mulberry silkworm: (Bombyx mori-Linnaeus)

• • • • It is an insect with complete metamorphosis, its life cycle goes through 4 different stages: egg, larva (silkworm), pupa, and moth. Each stage plays an important role in the silkworm’s life.
        • Larva (Silkworm) Stage: This is the stage of eating mulberry leaves to accumulate nutrients. The silkworm’s body grows very quickly during this stage; a mature silkworm (with sufficient nutrients) is 8,000 times larger than a newly hatched one.
        • Moth Stage: This is the adult stage where the male and female find each other to mate, and the female moth lays eggs.
        • Egg Stage: For multivoltine silkworm eggs, after the female lays them, they will hatch into silkworms in 8-10 days at 25°C. For bivoltine and univoltine silkworm eggs, after being laid, they enter a state of dormancy and must undergo a cold period. This is a genetic trait of bivoltine and univoltine silkworms formed in the cold conditions of temperate zones. After 4-5 months of winter cold, the dormancy (also called diapause) is broken, and the eggs hatch into silkworms. People have taken advantage of this characteristic to preserve eggs for a long time, along with methods to artificially break dormancy. Characteristics of silkworm eggs: oval, small, flat, with a hard outer shell. The shape varies depending on the breed. Univoltine eggs are the largest, followed by bivoltine eggs, and multivoltine eggs are the smallest. The eggs are milky white or slightly yellow, with many air holes on the surface.

• • • Cocoon Silk
      • A silkworm cocoon is the outer protective shell of the pupa, made of silk threads created from the protein in the mature silkworm, helping it withstand external conditions and natural enemies.
      • Thousands of years ago, people discovered how to produce silk thread from cocoons: the cocoon is softened in hot water, and the silk threads can be unwound. The fine, strong, and uniform thread can be used to produce beautiful and durable fabric.

• • • • Good cocoons depend on factors: breed and care during the mature silkworm stage (density, temperature, humidity, ventilation, light).
      • Main characteristics of reeling cocoons: color, cocoon shape, size, hardness, wrinkles, cocoon weight, shell weight, and shell ratio.

2. Properties of Silk Fiber in the safety document for the leather, down feather, and silk industry

• Unlike other natural fibers such as cotton, linen, wool, etc., silk does not have a cellular structure. In this respect, it is more like artificial and synthetic fibers. Each thread spun by the silkworm consists of two small filaments lying parallel to each other, made of Fibroin and coated with a layer of adhesive gum called Sericin. After the Sericin gum is completely removed, the silk is in the form of a single filament. Under the action of chemicals or mechanical forces, it can easily split into many small fiber bundles (fibrils). Through micro-electron microscopy, it has been observed that silk fibrils have a diameter of about 10nm. This fibrillation in the structure of silk is the reason it wrinkles and pills easily, which also depends on the breed and rearing conditions of the silkworm.
• In addition to Fibroin and Sericin, which are natural proteins, raw silk also contains some compounds soluble in ether and ethyl alcohol, and natural colorants, usually yellow. The amount of impurities in silk is not fixed but varies over a wide range depending on the breed and rearing conditions.
• The general composition of silk is as follows:

Component	Mass Ratio	Percentage %
Fibroin	70.0	80.0%
Sericin	20.0	30.0%
Impurities soluble in ether	0.4	0.6%
Impurities soluble in alcohol	1.2	3.3%
Minerals	1.0	1.7%

 

• When silk is boiled in a soap solution, all the above-mentioned impurities, except for Fibroin, are removed from the fiber, causing its weight to decrease by 20–30%. During the reeling process, Sericin is partially dissolved, so its content in raw silk is always lower than in the cocoon.
• Structure and properties of Fibroin:
  • Structure and chemical composition of Fibroin:
    • Fibroin belongs to the Scleroprotein class. Its elemental composition is as follows:

Component	Mass Ratio	Percentage %
Carbon	48.00	49.00 %
Hydrogen	17.35	18.89 %
Oxygen	26.00	27.90%

 

• • • Studying the amino acid composition of Fibroin, we see that it only lacks cystine and cysteine. Almost all amino acids found in natural proteins are present in fibroin, especially small-molecule amino acids like glycine, alanine, serine, and tyrosine, which account for a fairly high proportion.
    • For example: In every 100g of fibroin, there are 75g of glycine and alanine.
    • Amino acid components

Amino Acid Name	Mulberry Silk Fibroin	Mulberry Silk Sericin	Chinese Oak Silk Fibroin
Glycine	42.8	1.1	19.1
Alanine	33.5	10.1	54.0
Valine	3.2	1.2
Leucine	0.9	3.4	1.2
Isoleucine	1.1
Serine	16.2	33.9	10.6
Threonine	1.6	8.9
Cystine		1.0
Methionine
Aspartic Acid	2.8	9.0	5.6
Glutamic Acid	2.2	2.5
Arginine	1.0	3.7	1.1
Lysine	0.7	1.9	7.6
Phenylalanine	3.4	2.7	0.6
Tyrosine	12.8	3.8	9.2
Histidine	0.4	1.0	1.1
Proline	0.7	2.2	2.5
Tryptophan	0.6	1.0	1.4

 

• • • When Fibroin is hydrolyzed, pentapeptides are obtained, so here again, we see a structure that completely follows the polypeptide theory.
  • Physical structure of Fibroin:
    • Based on the polypeptides isolated during the hydrolysis of silk Fibroin, it has been concluded that:
    • The polypeptide chain of Fibroin has long segments composed only of glycine and alanine residues, or glycine and serine residues in sequence, while other amino acids present in Fibroin are concentrated in certain segments of the chain.
    • The polypeptide chain of Fibroin has the special characteristic of having few branches and containing many simple amino acids such as alanine, glycine, and serine.
    • Because the Fibroin of silk has a less compact structure in these amorphous regions, the functional groups here can easily react with chemicals. When dyeing, this part absorbs dye more easily than the parts with a microcrystalline structure.
    • One of the disadvantages of silk is that it easily changes shape and does not hold a crease for long, perhaps partly due to the lack of covalent cross-links between the chains. In terms of structure and some other properties, silk is similar to polyamide fibers.
  • Swelling and solubility ability:

Material	NaOH 5%	HCOOH 80%	Glacial CH3COOH	Conc. HCl	H2SO4 70%	Phenol 90%	Acetone	Dimethyl-formamide
Silk fiber (density 1.25 g/cm3)	Partially soluble	Completely soluble	Insoluble	Completely soluble	Completely soluble	Insoluble	Insoluble	Partially soluble

 

• • • Fibroin does not dissolve in alcohol, ether, petroleum ether, carbon disulfide, and other common organic solvents. In practice, it is insoluble in water, but water cannot be considered inert to Fibroin.
  • Effect of acids and alkalis:
    • Under the effect of alkalis, Fibroin, like other proteins, is very easily decomposed, yielding intermediate products from polypeptides to peptones and amino acids. Among all alkalis, caustic soda has the strongest effect on fibroin. In a 5-7% caustic soda solution at boiling temperature, the silk will be destroyed after a few minutes; even in dilute caustic soda solutions (0.01 – 0.1N) when heated, the silk is also severely damaged. Although weaker than caustic soda, salts such as Sodium Phosphate, Sodium Carbonate, and Sodium Silicate also damage the silk. Even solutions of soap, sodium pyrophosphate, and ammonium hydroxide, if not used in the correct dosage and processing conditions, will also damage the silk.
  • Effect of microorganisms:
    • Like wool keratin, Fibroin is resistant to the effects of microorganisms, but this is only relative. Only silk that has not been damaged by other agents is resistant to microbial enzymes. Silk that has undergone mechanical impact, although slowly, will still be destroyed by specific enzyme strains.
  • Effect of oxidizing agents:
    • Fibroin is very sensitive to the effects of oxidizing agents.
    • Therefore, during the chemical processing of silk, special attention must be paid to the effect of oxidizing agents. In practice, to bleach silk, a Hydrogen Peroxide (H₂O₂) solution is used because it has little effect on Fibroin. Bleaching solutions of Sodium Hypochlorite (NaClO) and Sodium Chlorite (NaClO₂) are less commonly used because even at low concentrations, they destroy Fibroin to form chloro-amino-acids, and can even break it down to keto-acids and chloramines.
    • The effect of reducing agents on silk has been little studied, as silk is resistant to common reducing agents used in the textile industry, such as Sodium Hydrosulfite, sulfurous acid, and its salts.
  • Structure and properties of Sericin:
    • Sericin is the protein component of silk that is less studied than fibroin. According to data published in world literature, the elemental composition of Sericin often varies, which indicates that its composition depends on the silkworm breed and the extraction method. In general, Sericin has the following elemental composition:

  Component	Percentage
  Carbon	44.32 – 46.29 %
  Hydrogen	5.72 – 6.42 %
  Nitrogen	16.44 – 18.30 %
  Oxygen	30.35 – 32.50 %
  Sulfur	0.15%

   

  • • From this, we see that Sericin differs from Fibroin in that its Carbon content is lower, while its Oxygen content is higher, and it contains a small amount of sulfur.
    • Like fibroin, the chemical composition of Sericin consists mostly of small-molecule amino acids such as glycine, alanine, and tyrosine, but the content of hydroxy acids (Serine), diamino acids, and aminodicarboxylic acids is significantly higher than in Fibroin.
    • The rate of Sericin removal, also known as the degumming rate, increases sharply when the temperature of the solution is raised above 100°C. For example, Sericin will be completely removed from the silk within 1 hour at 110°C.
    • Unlike Fibroin, Sericin is not resistant to the action of microbial enzymes and is easily hydrolyzed. In addition, if raw silk (silk that has not been degummed) is treated with formalin, the solubility of Sericin will be significantly reduced during degumming. This is likely because formalin also reacts with the amine groups in the side chains of Sericin to form methylene cross-links between the polypeptide chains.

  3. Applications in Daily Life in the Safety Document for the Leather, Fur, and Silk Industry

  • Silk is often used in fashion for items like evening gowns and wedding dresses, due to the luxury that silk fabric provides.
  • It is used in the production of bedroom items such as blankets and pillows. It is also applied in making vests, jackets, and office wear.
  • Additionally, silk is used for curtains due to its good moisture absorption and antibacterial properties, not to mention the elegance and sophistication it adds to a home. It’s also used to produce silk face towels, silk bath towels, scarves, linen trousers, etc. This type of silk is widely used in the West.
  • For generations, silk has been a source of pride for the Vietnamese people, contributing to the creation of distinctly Vietnamese products that are unlike any other material. Currently, in Vietnam and around the world, there is a trend towards feminine, gentle, and ethereal fashion styles. When one thinks of silk, products woven from 100% silk thread come to mind, with their soft, cool fabric that provides comfort to the wearer. Naturally, the price of products made from pure silk is not cheap at all.
  • Silk Ao Dai
    • With its advantages of softness and femininity, silk has made designs that can be somewhat restrictive, like the Ao Dai, much more comfortable to wear. The delicate silk threads, retaining their raw, rustic quality and closeness to nature, evoke the spirit of a tropical climate. High-quality silk material provides a pleasant feeling, and its simple, sophisticated style is favored by renowned designers worldwide to add a touch of grace to their creations.
  • Party Dresses and Gowns
    • For dresses and gowns for parties on hot summer days, choosing products made from silk is a smart choice for women, creating an appearance that is both elegant and classy. Whereas in the past, silk was only used for soft, classic, and gentle styles like the Ao Dai or Ao Ba Ba, today silk fabric is used for all kinds of styles, from tailored suits to swimwear, from comfortable loungewear to formal and polished office attire.
    • Furthermore, thanks to improvements in weaving techniques, silk is more diverse with types like Jacquard, crepe, taffeta, etc., used for making pillowcases, curtains, sofa covers, and more. Using silk to decorate a living room, whether for sofa upholstery, curtains, or tablecloths, is a very reasonable choice. The traditional monochromatic colors of silk such as brown, cream, and gold, combined with its smooth and glossy texture, will make your living room look luxurious and splendid, reflecting the status and personality of the homeowner.

  4. Situation of Silk Processing in the Safety Document for the Leather, Fur, and Silk Industry

  • According to information from the Ministry of Agriculture and Rural Development, the sericulture (silk farming) industry has been a strongly developing sector in Vietnam for a very long time, with its area, output, and value continuously increasing and establishing its position in the international market. The primary evidence is that Vietnam’s raw silk production ranks among the top 5 in the world, just behind China, India, Uzbekistan, and Thailand.
  • In 2019, cocoon production reached nearly 9,200 tons, raw silk production was over 1,500 tons, and over 5.2 million meters of silk fabric were produced. However, our country’s sericulture industry still faces many obstacles in state management, international cooperation, supply chain linkage, processing technology, quarantine, etc. Notably, although raw silk production increases annually, Vietnam currently has to import thousands of tons of raw silk from China, Brazil, etc., to process for Matsumura (Japan) for export to countries like Japan, Italy, India, and France.
  • “If Vietnam does not have a strong development strategy for the sericulture industry right now, we will not have enough raw materials for production in the next 10-15 years.” Therefore, there must be solutions to improve productivity, enhance technology in production and silk processing, diversify products, and support businesses in building brand identity for Vietnamese silk.

  ---

  III. THE DYEING PROCESS

  1. What is Dyeing? in the Safety Document for the Leather, Fur, and Silk Industry

  • Dyeing is the process of changing or darkening the color of an object or material with a synthetic or plant-derived substance. (Source: Vietnamese Dictionary)

  2. Dyes in the Safety Document for the Leather, Fur, and Silk Industry

  • Definition
    • Dye is a general term for colored organic compounds (of natural or synthetic origin) that are diverse in color and type. They have the ability to dye, meaning they can directly bind or attach color to a material.
  • How Dyes are Named
    • It consists of 3 parts:
      • Part 1: Written in full, indicating the technical classification of the dye.
      • Part 2: Written in full, usually adjectives describing the color of the dye.
      • Part 3: Written with letters and numbers indicating the shade and intensity of the dye. To indicate color intensity, two consecutive letters like BB, RR, etc., are used, or numbers are added like: 2R, 6B, 4G…

  3. General Structure that Creates the Color of Dyes in the Safety Document for the Leather, Fur, and Silk Industry

  • According to the viewpoint of Butlerov and Alekseev in 1876, O. Witt proposed that the color of organic compounds is due to the presence of chromophores in their molecules, which are groups of atoms with unsaturated valencies. Important chromophores include:
    • CH=CH the ethylene group
    • N=N the azo group
    • CH=N the azomethine group
    • N=O the nitroso group
    • NO₂ the nitro group
    • =C=O the carbonyl group
    • In addition to chromophores, to deepen the color, auxochromes are needed: -OH, -NH₂, -N(CH₃)₂

  4. Classification of Dyes in the Safety Document for the Leather, Fur, and Silk Industry

  • Based on origin, they are divided into 2 types: Dyes of natural origin and synthetic dyes. Synthetic dyes are divided by technical class and by chemical structure.
  • By chemical structure
    • Azo dyes
    • Anthraquinone dyes
    • Indigoid dyes
    • Aryl methane dyes
    • Nitro dyes
    • Nitroso dyes
    • Polymethine dyes
    • Sulfur dyes
    • Arylamine dyes
    • Azomethine dyes
    • Polycyclic vat dyes
    • Phthalocyanine dyes
  • By technical class
    • Direct dyes.
    • Reactive dyes.
    • Basic-cationic dyes.
    • Mordant dyes.
    • Soluble and insoluble Vat dyes.
    • Sulfur dyes.
    • Azoic dyes.
    • Disperse dyes.
    • Oxidation dyes.
    • Pigment dyes.
    • Acid dyes.
  • Type of Dye Studied
    • Acid dyes are types of dyes that are generally soluble in water and have a wide range of uses. Besides dyeing wool, silk, and polyamide fibers, some are used for dyeing leather and fur. This class of dyes is called “acid” because they fix onto the fiber in an acidic environment, while the dyes themselves have a neutral reaction.
    • In terms of chemical structure, most acid dyes belong to the azo group, with a smaller number being derivatives of anthraquinone, triarylmethane, xanthene, and azine; some form complexes with metals. By technical properties, acid dyes are divided into 3 groups:
      • Conventional acid dyes.
      • Mordant acid dyes.
      • Metal-complex acid dyes.
    • These three groups of dyes share the common characteristic of having a full range of colors, which are bright and pure. Most of them are salts of strong acids and strong bases, so when dissolved in water, they dissociate into ions as follows:
      • Ar-SO₃Na → Ar-SO₃^– + Na⁺
    • The colored ions of the dye are negatively charged (Ar-SO₃^–) and will be adsorbed onto the positively charged sites of the material. This is how they are fixed or retained on the material by ionic or salt bonds, which is a specific characteristic of acid dyes. In addition, they are also bonded to the materials by van der Waals forces, hydrogen bonds, and coordinate bonds, but these bonding forces are not strong. The following are three common acid dyes:
  • Dye: Acid Yellow 17
    • Molecular Formula: C₁₆H₁₀Cl₂N₄Na₂O₇S₂ Molecular Weight: 551.28
    • Structural Formula:

  

  • Dye: Acid Blue US1
    • Molecular Formula: C₂₇H₃₁N₂NaO₆S₂ Molecular Weight: 566.66
    • Structural Formula:

  

  • Dye: Acid Red 52
    • Production Name: Sulforhodamine B International Names: Sulforhodamine b monosodium salt; sulforhodamine b; phloxine rhodamine; xylene red; xylene red b; (6-(diethylamino)-9-(2,4-disulfophenyl)-3h-xanthen-3-ylidene)diethylammonium; acidleatherredkb; AcidroseredB.
    • Molecular Formula: C₂₇H₂₉N₂NaO₇S₂ Molecular Weight: 580.65
    • Structural Formula:

  

  5. Situation of the Dyeing Industry in the Safety Document for the Leather, Fur, and Silk Industry

  • For many decades, the textile dyeing industry has held an important position in the national economy. With state-owned enterprises, private enterprises, joint venture projects, and 100% foreign-invested factories, along with many small, medium, and large private complexes operating in the fields of spinning, weaving, and dyeing, the scale and strong development orientation of this industry are evident. However, textile dyeing wastewater has high alkalinity or acidity, deep color, and contains many organic and inorganic substances that are toxic to aquatic life and affect public health.
  • The textile dyeing industry is one of the industries with a long-standing tradition in our country. Along with the country’s development, the textile dyeing industry has undergone many changes, with an increasing number of enterprises and factories being established, including those in the non-state economic sector, joint ventures, and 100% foreign-invested enterprises. The textile dyeing industry is also a rapidly developing sector due to domestic and foreign investment. In the current economic conditions, industrial textile dyeing occupies a significant position in the national economy, contributing substantially to the state budget and providing employment for many workers. Textile dyeing is a diverse industry in terms of product types and involves changes in raw materials, especially dyes.
  • Some large-scale factories and enterprises in Ho Chi Minh City are as follows:

  Company Name	Annual yarn demand (tons)				Dyeing Chemicals
  	Cotton	PE	PE/Co	Viscose
  Dong Nam Textile	1500	3000
  Phong Phu Textile	3600	1400	600		465
  Thang Loi Textile	2200	500
  Thanh Cong Textile	1500	2000			Dyes: 90 Basic Chemicals: 2000 Auxiliaries: 600
  Viet Thang Textile	2400	1200			394
  Phuoc Long Textile	1200				140

   

  • Survey results show that most large factories import equipment and chemicals from many different countries:
    • Equipment: from Germany, USA, Japan, Poland, India, Taiwan, South Korea.
    • Chemicals: from Japan, Germany, Switzerland.
    • Basic chemicals: from China, Taiwan, India, Vietnam.
  • With the volume of chemicals used, textile dyeing wastewater has a high level of pollution. Textile dyeing wastewater is very diverse and complex. It is estimated that the types of chemicals used, such as dyes, surfactants, electrolytes, soaking agents, conditioning agents, starch enzymes, oxidizing agents, and many other chemicals dissolved as ions, increase toxicity not only in the short term but also long-term for life.

  6. Relevant Legal Documents in the Safety Document for the Leather, Feather, and Silk Industry

  • Circular 06/2020/TT-BLĐTBXH – Promulgating the list of jobs with strict requirements for occupational safety and health.
  • QCVN 13-MT:2015/BTNMT National Technical Regulation on textile dyeing wastewater.
  • National Technical Regulation QCVN 01:2017/BCT on the limits of formaldehyde and aromatic amines converted from azo dyes in textile products.
  • National Standard TCVN 7835 – F06: 2007 (ISO 105 – F06: 2000). Textiles – Methods for determining color fastness – Technical requirements for adjacent fabric: silk.
  • TCVN 4536: 2002 (ISO 105-A01:1994), Textiles – Methods for determining color fastness – General principles.
  • TCVN 2366:1987. Mulberry raw silk – Technical requirements.
  • (This standard replaces TCVN 2366-78 and applies to raw silk with fineness of 1.44 – 1.67 tex (or 13-15 denier), 2.22 – 2.44 tex (or 20-22 denier); 3.11 – 3.33 tex (or 28-30 denier); reeled from white or yellow cocoons).
  • The Ministry of Health issued Circular 22/2016/TT-BYT on QCVN 22:2016/BYT regarding Lighting – Permissible Levels in the Workplace.

  ---

  CHAPTER II: HAZARDS CAUSING UNSAFETY

  I. UNSAFE HAZARDS IN THE PRODUCTION AND PROCESSING OF LEATHER, FEATHERS, AND SILK

  1. Fire and Explosion in the Safety Document for the Leather, Feather, and Silk Industry

  • The leather, feather, and silk production and processing industry involves highly flammable materials like various types of fabrics. When a fire or explosion occurs, the blaze often erupts and spreads rapidly, causing severe consequences.
  • Some common causes of fire:
    • Impact of open flames, embers, sparks;
    • Effects of electrical energy;
    • Friction and impact between objects;
    • Chemical reactions of chemicals used in the production and processing of leather, feathers, and silk.
    • During the production and processing of leather, feathers, and silk, the operation of machinery and equipment generates heat, which can lead to the risk of thermal burns for workers.

  2. Electrical Sources in the Safety Document for the Leather, Feather, and Silk Industry

  • When operating machinery for the production and processing of leather, feathers, and silk that uses electricity, there is a risk of electric shock that can paralyze the respiratory and cardiovascular systems of workers. Protective measures must be in place to prevent electrical accidents at these production facilities.

  3. Entanglement Risk in the Safety Document for the Leather, Feather, and Silk Industry

  • * Driving and moving parts of machinery for producing and processing leather, feathers, and silk:
    • Gears; Belts, chains, moving machines;
    • Conveyor belts; Rolling, winding, stamping machines; Grinding, crushing machines; …

  

  • Causes of occupational accidents:
    • Loss of balance while performing tasks; hand entanglement;
    • Not using specialized tools or personal protective equipment;
    • Failure to guard hazardous areas; Lack of safety supervision.

  4. Environmental Pollution in the Safety Document for the Leather, Feather, and Silk Industry

  • For many years, residents in some areas have been living in a heavily polluted environment due to emissions and a strong stench from a feather processing facility, which produces raw materials for livestock and poultry feed.

  

  • According to reports, some facilities that process feather meal for livestock and poultry feed also collect and treat industrial and agricultural waste, recycling and reusing post-slaughter waste, and producing fish meal and meat meal.
  • However, whenever the facility operates, it often emits a very strong, pungent odor. This odor spreads everywhere with the wind, entering homes, schools, etc., causing serious environmental pollution and greatly affecting the health and daily life of the people.
  • A resident said that because they constantly have to endure the unpleasant odor emitted from this facility, people have to wear masks tightly both at home and at work to reduce the smell. Furthermore, many households here often have to keep their doors and windows closed, not daring to let the elderly and children go outside to play or relax. Some facilities have not registered as a source of hazardous waste; have not submitted periodic hazardous waste management reports as required; lack signs, warning symbols, and waste codes; and the production area has a characteristic odor from the raw feather material. The inspection team has requested the facility to conduct periodic environmental monitoring in accordance with the approved environmental protection plan. At the same time, the facility was required to continue reviewing production stages that generate odors to take measures to thoroughly minimize the odor, preventing it from affecting the surrounding environment.
  • In addition, fire prevention and fighting (FPF) measures at some facilities are not truly ensuring safety. Some firefighting equipment has run out of gas, failing to ensure firefighting capability, and the surrounding access roads are not adequate for fire trucks to enter and exit the facility in case of a fire or explosion.
  • Not trading the environment for economic goals – that is the very clear guiding principle of the Government on environmental issues.

  5. Impact from Chemicals

  • Wastewater
    • Wastewater from the tanning industry has variable characteristics and depends on each production stage, generated from the following main activities:
      • Wastewater from cleaning workshops, equipment, and machinery;
      • Wastewater from the soaking stage;
      • Wastewater from the dehairing and liming stage;
      • Wastewater from the deliming and bating stage;
      • Wastewater from the tanning stage;
      • Wastewater from the finishing stage.
  • Solid Waste
    • The sources of solid waste from the tanning process include fat, fleshings, trimmings, leather shavings, chrome shavings, lime sludge, and coal slag, waste oil from auxiliary stages. The amount of solid waste generated from 1 ton of raw hide is shown in the table.

  No.	Pollutants	Unit	Mass
  1	Fat, fleshings	Kg	150 – 200
  2	Trimmings	Kg	90 – 100
  3	Chrome shavings	Kg	50 – 60
  4	Shavings, post-tanning trimmings	Kg	50 – 60
  5	Leather dust, post-finishing trimmings	Kg	11 – 22
  6	Coal slag	Kg	30 – 50

   

  • Air Emissions
    • Air emissions from a tannery are mainly generated from the following main stages: Emissions from the use of boilers, characterized mainly by VOCs, CO, NOx, SO₂, and dust.
    • Emissions from the soaking, dehairing, liming, and deliming stages due to the decomposition of organic substances and proteins, producing gases like NH₃, H₂S, and other N, S compounds. These emissions have a very unpleasant foul odor, directly affecting the health of workers and the surrounding area.
    • Vapors of volatile acids. Acid vapors adversely affect the respiratory system of workers.
    • Solvent vapors from the finishing stage can adversely affect the health of workers in this area.

  6. Effects on Human Health in the Safety Document for the Leather, Feather, and Silk Industry

  • Feather allergens are one of the main causes of occupational allergic rhinitis, especially among workers at poultry farms, processing facilities, and factories producing household goods using feather materials.
  • Allergic rhinitis is a very common disease in otolaryngology and allergy specialties worldwide, and it is a condition caused by a disordered immune response. The treatment strategy for allergic rhinitis includes four basic principles: avoiding contact with the allergen, treatment with anti-allergic drugs, specific immunotherapy, and patient education.

  ---

  II. UNSAFE HAZARDS IN DYEING WORK

  1. Fire and Explosion in the Safety Document for the Leather, Feather, and Silk Industry

  • Some flammable and explosive chemicals used in dyeing are those that can self-decompose, causing fire or explosion, or can form flammable or explosive mixtures with other substances under certain conditions of composition, temperature, humidity, and pressure. The sub-groups and list of flammable and explosive chemicals are specified in Appendices B and C of standard TCVN 5507:2002 “Hazardous Chemicals – Code of practice for safety in production, business, use, storage, and transport.”
  • During the production, storage, transportation, and use of chemicals for dyeing, if safety procedures are not strictly followed, chemical fire and explosion incidents can easily occur. These are abnormal events related to: Fire, explosion, leakage, or dispersion of harmful chemicals that cause or have the potential to adversely affect human health, damage property, harm flora and fauna, the environment, and can negatively impact social security.
  • Therefore, a suitable fire prevention and fighting plan is needed in accordance with Circular No. 66/2014/Ministry of Public Security.

  2. Risk of Chemical Splashes Causing Burns in the Safety Document for the Leather, Feather, and Silk Industry

  • During the preparation of dyes, chemical splashes can cause burns to workers if safe working measures and appropriate personal protective equipment are not in place.

  3. Slips and Falls in the Safety Document for the Leather, Feather, and Silk Industry

  • Workers may slip and fall on pathways and in the dye preparation area. These areas should be regularly cleaned, tidied, and kept clean, dry, and well-ventilated.

  4. Chemicals in the Dyeing Industry in the Safety Document for the Leather, Feather, and Silk Industry

  Currently, most of these auxiliary agents have to be imported in large quantities, causing the proportion of raw and auxiliary material costs paid in foreign currency to be quite high in the production cost of dyed textile products. The State-level Consumer Goods Development Program (KC-07) has assigned the Institute of Industrial Chemistry (VHHCN) to lead the project KC-07-16 to research and produce some high-quality auxiliary agents for the textile industry to gradually replace imported products based on available domestic raw materials. Below are some new products that have been researched, developed, and put into pilot production in the textile industry with good results.

  • Acid Dyes
    • The name “acid dye” comes from the fact that these dyes can dye certain types of fibers in an acidic environment (animal and polyamide fibers). They consist of a chromophore group and one or more sulfonate groups, which make them soluble in water.
    • Today, the main types of acid dyes are still widely used, and their color range is one of the most complete. Their only drawback is that their color fastness is not good against all harmful environmental factors.
  • Metal-Complex Dyes
    • To simplify the work of dyeing technicians by eliminating the mordanting process, the idea of incorporating the metal tightly within the dye itself to form a metal complex, instead of precipitating the metal onto the fiber, led to the creation of metal-complex dyes.
    • Such metal-complex dyes include dyes containing a metal atom (Cr, Ni, Co). This metal atom can combine with one dye molecule (1:1 metal complex) or with two dye molecules (1:2 metal complex).
    • These types of dyes can be used to dye wool, silk, or polyamide, and the resulting products have very high color fastness but are generally not very bright.
  • Reactive Dyes
    • Reactive dyes are the newest type of dye. Their name reflects the way they bond with the fiber. The reactive dye molecule consists of a chromophore group and a chemically reactive functional group that ensures the formation of a covalent bond with the fiber, by reacting either with the hydroxyl groups of cellulose or with the amine groups in wool or polyamide.

    – Different forms of chemically reactive functional groups are utilized, such as monochlorotriazine, dichlorotriazine, vinylsulfone… Due to the presence of a covalent bond between the fiber and the dye, it can be assumed that colors dyed with reactive dyes have high stability, high color fastness, and bright shades. This type of dye does not have good resistance to adverse weather conditions and Chlorine.

  • Wetting Agent Wetta-NTD-93
    • Greige fabric contains up to 6% natural impurities (wax, pectin…), and during the weaving process, it also carries sizing and mechanical impurities. Therefore, if it does not go through the scouring and bleaching stage, it will be very difficult to absorb water and chemical solutions or dyes. Some types of fabric intended to be worn white, although they do not need dyeing and printing, still need to be scoured and bleached to be soft and have good water and sweat absorbency.
    • Therefore, in the textile dyeing industry, high-absorbency auxiliary agents are often used for scouring and bleaching to chemically treat the fabric before dyeing and printing. The wetting agent Wetta-NTD-93 is produced from certain specific vegetable fatty oils, synthetically modified to become a derivative whose main active ingredient is sodium sulfoester of ricinoleic acid.
    • The above active ingredient is formulated with some additives to enhance quality and provide selective activity. Through research, we have selected a suitable production technology and additives to create a product that has both high wetting ability and rapid penetration, as well as the necessary cleaning and emulsifying properties to meet the technological requirements for pre-treating cotton fabrics, cotton-blend fabrics, and other knitted goods.
    • Main technical characteristics of the product. It is a viscous, dark yellow liquid with a mild odor. The chemical composition includes a mixture of anionic surfactants, capable of reducing surface tension and having rapid wetting properties. Surfactant content in the product: 65 ± 1%; specific gravity at 20°C: nearly 1.1; pH = 7. It is easily soluble in water and does not precipitate in hard water.
    • Dominant features: wetting, emulsifying, and cleaning. It has high wetting ability and moderate foaming. It is stable in acidic, weak alkaline, and neutral environments, and its activity is not reduced in the presence of electrolytes.
    • The wetting agent Wetta-NTD-93 provides highly effective cleaning when scouring cotton fabrics, blended fabrics, and knitted fabrics in both atmospheric and high-pressure equipment, with the capillarity of cotton fabric consistently reaching over 130mm in 30 minutes.
    • It is also used to prepare dye solutions with direct dyes, sulfur dyes, insoluble azoic dyes, and reactive dyes.
    • The wetting agent Wetta-NTD-93 has been tested and applied on a large scale for tens of thousands of meters of fabric on the production line of the dyeing and printing enterprise (8-3 Textile Company) with good results.
  • Dispersing Agent Dispa-PTD-93
    • Dispersing agents are surfactants that can reduce the surface tension of fiber materials and have high dispersing properties. They are used in dyeing technology to make the dye a fluid, uniform solution that easily penetrates the fabric.
    • Items dyed with vat dyes or azo dyes, when washed with soap, must have a dispersing agent added to the washing solution to increase rubbing fastness.
    • When processing 100% synthetic fiber materials, a dispersing agent is also needed to reduce static electricity. In the production of printing pastes, dispersing agents are added to make the paste uniform and stabilize the system, preventing clumping, screen clogging, and allowing for easy penetration into the fabric. Based on available raw materials, VHHCN has successfully researched and produced the dispersing agent Dispa PTD-93.
    • The main active ingredient of the dispersing agent has the general chemical formula C₂₁H₁₄O₆S₂Na₂. The dispersing agent is a condensation product of beta-naphthalene-sulfoacid with formaldehyde, then neutralized with NaOH, supplemented with some additives, and standardized into a commercial-grade auxiliary, with full active ingredients and performance comparable to commercial products from various companies worldwide, for example: Kortanol NNO (Sec), Irgasol P (Ciba-Geigy), Univadin DPL (Japan), Dispergato NP, Xotamol BC, Votamol BC (former Soviet Union).
    • The product is manufactured on a technology line with a capacity of 50 tons/year, which we researched, designed, manufactured, and built ourselves. The technical specifications of the dispersing agent are as follows:
    • It is a dark brown liquid, highly soluble in water, stable in weak alkaline and weak acid solutions within a pH range of 4 – 13, and stable in hard water.
    • Main active ingredient content (calculated as dry matter): 30 – 35%. Water-insoluble content: 0.016%. The stability of a dye solution containing the dispersing agent at a concentration of 2g/l remains good after 36 hours.
    • The pH of a solution containing 1% of the product: 6.5 – 7.5
    • The product has very good dispersing properties, preventing precipitation and deposition of dye during temperature elevation, and re-dissolving any dye that has agglomerated and settled under high-temperature dyeing conditions. Therefore, it is particularly suitable and convenient when preparing dye solutions for yarn in bobbin form; ensuring even dyeing and color development for bright shades, increasing brightness and rubbing fastness even for dark colors, without reducing light fastness.
    • The dispersing agent is used for dyeing synthetic fabrics and cotton blends. It is also used in many other industries, especially when some additives are changed, it can form an emulsifier used for processing pesticides in the agrochemical industry. The dispersing agent Dispa PDT-93 has been mass-tested on the production line of the Dyeing and Printing Enterprise of the Hanoi 8-3 Textile Company. It has been used to print and dye tens of thousands of meters of fabric with good quality, fully capable of replacing similar types of dispersing agents that still have to be imported. Two new products: the wetting agent Wetta NTD-93 and the dispersing agent Dispa PDT-93 have been produced in large quantities on a technology line with a capacity of 50
    • 100 tons/year, which we designed and manufactured ourselves. VHHCN has signed a contract to supply the 8-3 Textile Company for mass application on its production line from 1999 to the present, and the product completely replaces similar products that were previously imported.
  • Dyeing Auxiliaries
    • Fortaric LD-P: Levelling and dispersing agent for disperse dyes.
    • Sonadon D-72: Levelling and dispersing agent for disperse dyes, low-foaming, effective.
    • Sonadon DP-S: Levelling and dispersing agent for disperse dyes.
    • Sonalin RS: Levelling agent for reactive dyes, stable in hard water, low-foaming.
    • AVCO-BUFFER V (Fortaric RD-90): Alkaline buffer for dyeing Cotton with reactive dyes. Stable pH throughout the dyeing process, economical.
    • Fortaric RD-18: Alkaline buffer for dyeing Cotton with reactive dyes, stable pH throughout the dyeing process, economical.
    • Sonsoft A-G: Lubricant, anti-crease agent. Non-foaming. Effective.
    • Forlube A-F: Lubricant, anti-crease agent. Non-foaming. Effective.
    • Fortaric F-89: Anti-foaming agent. Highly effective. Economical dosage.
  • Specialty Dyes for Wool Dyeing
    • UNISOL: A bromoacryl reactive dye (similar to LANSOL by Ciba).
    • UNISET: 1:2 metal complex acid dye (similar to LANASET by Ciba).
    • UNILAN: Asymmetrical 1:2 metal complex acid dye.
  • Reactive Dyes for Cotton Dyeing
    • UNICION: H-E type (2x Monochlorotriazine).
    • UNISUPRA: Bifunctional type (similar to Ciba’s HW series).
    • UNITIVE MS: Pyrimidine type (similar to LEVAFIX by Ciba).
    • UNIFIX
  • Dyes for Nylon Dyeing:
    • UNICRON: Levelling acid dye type (similar to TECTILON).
    • UNIMIDE: Acid dye type (similar to ERIONYL).
    • UNISET: 1:2 metal complex acid dye for dyeing Wool and Nylon.
    • UNISET-PN: 1:2 metal complex acid dye for dyeing Wool and Nylon with high fastness and depth.
    • UNILAN-S: 1:2 metal complex acid dye for dyeing Wool and Nylon with medium depth properties.
    • UNISET BLACK ACE: 1:2 metal complex acid dye for dyeing Nylon and microfibers with high wash fastness and no need for post-dyeing treatment.
  • Specialty Dyes for Wool and Nylon Blends
    • UNISET WN: 1:2 metal complex acid dye for dyeing deep shades on Wool blends and
  • Acid Dyes for Leather and Fur Dyeing
    • PATASET-H: 1:2 metal complex acid dye (similar to SELASET).
    • UNILEATHER: Inorganic acid dye.
  • Dyes for Wool
    • UNISOL: Unisol consists of organic and anthraquinone dyes that have a sulfone group and one or two bromoacrylamide reactive groups. Due to its covalent bonding, it provides excellent reproducibility and wet fastness without chlorine treatment (super wash).
    • UNISOL CQ: The Unisol CQ group is suitable for dyeing with high or medium depth as they consist of UNISOL components.
    • UNISET: The Uniset group is fundamentally modified: 1:2 metal complex and reactive dyes with high performance in fastness and most uniform properties.
    • Most shades can be dyed economically on Wool by using a simple combination of these dyes.
    • UNILAN: is an asymmetrical 1:2 metal complex dye that has a sulfone group in the molecule. Because it is hydrophilic, it ensures good solubility even in cold conditions. It is very suitable for dyeing or printing on Wool, Polyamide, as well as other fibers.
    • UNITIVE: The Unitive MS group are reactive dyes. They produce bright colors, excellent fastness, and stability in alkaline solutions during dyeing with medium and high depth shades. It is suitable for dyeing medium and deep shades (over 2% concentration) where a fastness level of more than 4 is required.
    • UNIFIX: Unifix is a reactive dye for Cotton that can be dyed at low temperatures. It produces light and bright colors, has high fixation, and is very stable in alkaline solutions. It allows for cost reduction in two aspects: energy, due to low-temperature dyeing, and dye, due to higher fixation and less residual dye in the dye bath.
  • Dyes for Cotton
    • UNICOIN: This is an H-E type that consists of 2 monochlorotriazine structures. It has excellent solubility without salt and is suitable for high-temperature dyeing from 80 to 100 degrees C with low reactivity and high color fidelity. Above all, this type is suitable for dyeing dense fibers.
    • UNIUPRA (bifunctional): It includes a reactive group for general cotton dyeing, especially in CPB and exhaust dyeing. It has high solubility, thermal stability (from 60 to 80 degrees C), and compatibility.
  • Dyes for Nylon
    • UNICRON: Unicron is a leveling acid dye. It is suitable for dyeing Nylon and Wool. It can also be used for carpet dyeing and is widely used for printing. Its outstanding properties are low migration, high uniform coverage, good fastness, compatibility and reproducibility, and good color uniformity.
    • UNIMIDE: Unimide was specially developed for dyeing polyamide fibers with medium depth. It has outstanding properties such as high light fastness, high uniform coverage, good wet fastness, and high compatibility.
    • UNISET: Uniset is an improvement of 1:2 metal complex dyes and high-reactivity dyes, thus it has similar properties. Most shades can be created economically through a simple combination of Uniset dyes.
    • The majority of shades created on nylon material use a simple combination of these dyes. Uniset dyes are suitable for high-quality dyeing requirements.

  5. Entanglement in the safety document for the leather, down feather, and silk industry

  • Machinery and equipment operating during dyeing that are not safely guarded can cause entanglement and pose a danger to the lives of workers.

  6. Environmental Pollution in the safety document for the leather, down feather, and silk industry

  • The chemical processing of textile materials, also known as “wet processing” (pretreatment), dyeing, printing, and sometimes final finishing, belongs to a water-intensive industry. It is estimated that processing 1kg of dyed textiles requires 50 to 300 liters of water and releases nearly the same amount of wastewater.
  • The level of wastewater pollution mainly depends on the chemicals, auxiliaries, and dyes used, and on whether the applied technologies are outdated, average, or advanced and modern.
  • Wastewater pollutants are divided into 3 main groups
    • Group One: substances toxic to microorganisms and fish
      • Caustic soda (NaOH), Na₂CO₃ are used in large quantities for scouring cotton fabrics and treating blended fiber wastewater. Unrecovered soda discharged at high concentrations.
      • Inorganic acids, such as H₂SO₄, used to neutralize caustic soda and “develop” soluble vat dyes (indigosols).
      • NaClO used for bleaching cotton fabrics and stone washing, sodium chlorite (NaClO₂) for bleaching knitwear.
      • High concentrations of inorganic reducing agents such as sodium sulfide (Na₂S) used in sulfur dyeing or sodium hydrosulfite (Na₂S₂O₄) in vat dyeing.
      • Chlorinated organic solvents, such as carriers used for dyeing polyester at 100°C or polyester/wool blends at temperatures >100°C.
      • Formaldehyde in color fixing agents and anti-wrinkle finishing agents.
      • Heavy metals may be present in industrial caustic soda produced using mercury electrodes. Heavy metal impurities (Cu, Cr, Zn, Pb, Co, Ni) are present in some dyes used, especially vat dyes and even some reactive dyes. A quantity of “AOX” (adsorbable organic halogens) enters the wastewater from some vat, disperse, reactive dyes, and a few pigments.
      • Non-ionic wetting and washing agents based on alkylphenol ethoxylates “APEO” can be biodegraded up to 80%, but the degradation products are toxic to fish.
      • Glauber’s salt (Na₂SO₄) used in reactive dyeing is discharged at high concentrations (>2g/l).
    • Group Two: substances difficult to biodegrade
      • Most dyes and optical brightening agents “OBA”.
      • Most emulsifiers, complexing agents, chelating agents, and softeners.
      • Sizing agents for polyester and blended yarns such as “PVA” and polyacrylates.
      • Synthetic polymers often used as finishing agents.
      • Synthetic binders in pigment printing.
      • Washing agents with aromatic rings, long alkylene oxide chains, or branched alkyl chains.
      • Mineral oil and silicone removed during the pretreatment of synthetic fabrics (such as spandex fibers).
    • Group Three: substances with low toxicity that can be biodegraded
      • Fibers and their natural impurities removed during pretreatment.
      • Unmodified starch (cassava starch) used for warp sizing.
      • Washing agents with straight-chain alkyls, soft detergents.
      • Acetic acid (CH₃COOH) and formic acid (HCHO) used for pH adjustment.
      • Neutral salts at low concentrations.

  7. Wastewater from the Dyeing Industry in the safety document for the leather, down feather, and silk industry

  • Wastewater sources in textile dyeing technology originate from the following stages:
    • Sizing.
    • Desizing.
    • Scouring, bleaching.
    • Dyeing and finishing.
    • The majority of water is used in the washing process after each stage.
    • Characteristics of production wastewater include:
    • Suspended solids.
    • Wastewater from textile dyeing often has high temperature, high pH, contains many types of chemicals and dyes that are difficult to decompose, and has high color.
    • Salts, organic chemicals in dyes and inks.
    • Surfactants.
    • Electrolytes, wetting agents, environment-creating agents.
    • Enzymes, starch.
    • Oxidizing agents.
  • With the characteristics of textile dyeing wastewater as described above, if not treated properly, it will cause environmental pollution, especially the pollution of surface water and groundwater.
  • According to QCVN 01: 2017/BCT – National Technical Regulation on the limit of formaldehyde content and aromatic amines derived from azo dyes in textile products.
  • Limit on formaldehyde content
    • The formaldehyde content in textile products must not exceed the values specified in the following table:

  No.	Textile Product Group	Maximum Limit (mg/kg)
  1	Textile products for children under 36 months	30
  2	Textile products in direct contact with skin	75
  3	Textile products not in direct contact with skin	300

   

  • • Limit on the content of aromatic amines derived from azo dyes
      • The content of each aromatic amine must not exceed 30 mg/kg. The list of aromatic amines derived from azo dyes is specified in Appendix II of this Regulation.

  ---

  CHAPTER III: CONTROL AND PREVENTION MEASURES

  I. SYSTEM CONTROL MEASURES

  1. Identification of hazardous and harmful factors in the production and processing of leather, down feathers, silk, and dyeing work

  • Hazardous Factors
    • These are factors that, when impacting the human body, often cause immediate accidents such as injuries, crushing of body parts, destruction of the human body, sometimes leading to death.
    • Transmission mechanisms of machinery and equipment used in the production and processing of leather, down feathers, silk, and dyeing.
    • Electrical source: During the production and processing of leather, down feathers, silk, and dyeing, electrical shock accidents can occur due to various reasons.
    • Heat source: Thermal pollution is a type of pollution that needs attention in the textile – dyeing industry. Heat is mainly generated from heat transfer through the walls of boilers, machinery and equipment using steam (scouring, bleaching, dyeing machines, fabric stenters), and the system of steam and hot gas pipelines;
    • Leakage from the steam pipe system, valves, and joints in the piping system; Heat radiation and water evaporation from fabric drying machines. The total amount of this heat released into the workshop space is very large, causing the indoor temperature to rise, which can be 2 to 5 degrees C higher than the outside ambient temperature (not including the influence of regional climatic conditions), affecting the human respiratory process, negatively impacting health and labor productivity. In addition, high temperatures also have the potential to cause fire and explosion incidents, so it is necessary to assess the impact of pollution to have appropriate treatment and mitigation measures.
    • Splashing: Chemicals, raw materials for producing leather, down feathers, silk, and dyeing splashing onto workers during work. Leather, down feather, and silk production facilities need to have safety measures such as: Using covers, shielding nets; Maintaining a safe distance as regulated; Using PPE.
    • Sharp objects: Needles, scissors, circular cutting knives, machinery, equipment, etc., used in the production and processing of leather, down feathers, silk, and dyeing can injure the skin, fingers, or other body parts of workers. Machines, equipment, and tools with sharp parts must have guards, barriers, and be isolated. Employers must organize safety training and provide appropriate personal protective equipment for employees when working with sharp objects. Technical measures should be prioritized to minimize contact with sharp objects.
    • Falls, collapses: Prevent unauthorized people and vehicles from entering hazardous areas; use equipment that ensures safety when lifting/lowering goods, materials, machinery, and equipment during the production and processing of leather, down feathers, silk, and dyeing;
    • Do not place materials near the edge of floors or upper levels;
    • There must be floors, railings, and safety nets when working at height; There must be solid support when working in areas prone to collapse;
    • Fire and explosion: A characteristic of the Textile – Dyeing industry is the use and storage of large quantities of fuel (oil, coal) and raw materials (chemicals, fabrics, yarn, cotton). Therefore, it is necessary to have incident prevention measures such as: lightning protection, protection against short circuits, and especially fire and explosion prevention. When fire or explosion incidents occur, they can lead to significant socio-economic damage and seriously pollute all three ecosystems of water, land, and air. Furthermore, it affects the lives of people, domestic animals, and the property of people in the area.
    • Fire and explosion prevention: Since most raw materials in the factory are flammable and can easily catch fire, especially during the dry season. During working hours, workers must wear personal protective equipment and necessary equipment such as masks… When working in an environment with toxic gas emissions, special respiratory masks must be used.
  • Harmful Factors
    • These are unfavorable working condition factors that exceed the limits of permitted occupational hygiene standards, reducing workers’ health and causing occupational diseases, such as microclimate, noise, vibration, radiation, light, dust, toxic substances, vapors, gases, and harmful organisms.
    • Harmful factors in production are factors that cause illness to workers.
    • Occupational harmful factors are factors present in the production process, workplace, that adversely affect the health and work capacity of employees.
    • Chemicals
      • When handling chemicals for the production and processing of leather, down feathers, silk, and dyeing, safety techniques must be observed. A safety instruction board must be hung in the workroom, and workers must be fully aware of it. If chemicals get on hands or feet, they must be washed immediately with water and then with a soda or acetic acid solution. When opening chemical bottles, care must be taken to prevent chemicals from splashing out. Lids of flammable chemical containers must not be heated over a flame to open. Chemical users must have a firm grasp of the properties of each type of chemical. Chemicals in containers must be clearly labeled. When it is necessary to dilute acid, the acid must be poured into water, not water into acid.
      • In case of an acid spill, sand should be poured on it, then the sand should be swept out of the room, and the area washed with a soda solution. Be careful when carrying a large container of concentrated acid or alkali. When diluting alkali, use rubber gloves, safety glasses, and a hat. Note that solid alkali can easily cause severe burns.
      • When working with organic solvents, be cautious, as prolonged exposure is very harmful. Do not heat these substances without a lid.
    • Microclimate
      • All instructions on occupational safety, fire prevention and fighting regulations, and chemical hazard prevention must be strictly followed. Especially the issue of industrial hygiene. Below are some measures to combat heat and humidity, ensuring a proper microclimate in the working conditions:
        • The workshop must have natural ventilation, making full use of the prevailing wind direction, with a reasonable layout.
        • Regularly check and maintain leaks in the steam and hot gas pipeline system.
        • Strictly implement the operating procedures for technological equipment, accurately measure raw materials and fuel so that the process runs at a high level of stability, reducing waste, and stabilizing the composition and properties of the waste to facilitate waste management and treatment.
    • Microorganisms
      • Workers exposed to pathogenic microorganisms, bacteria, viruses, parasites, insects, and molds during the production and processing of leather, down feathers, silk, and dyeing may suffer health effects and occupational diseases.
    • Vibration, Noise
      • The characteristic noise of the textile – dyeing industry depends on the generation of machinery and is mainly emitted from weaving machines, fabric cross-cutting machines (operating on a stamping principle), dyeing-washing-centrifuging machine clusters, boilers, and especially aerodynamic noise from the continuous flow of gas and steam in pipelines.
    • Ergonomics
      • Accident prevention: Design a comfortable and reasonable working environment, ensure safety components are in place, and use tools and equipment suited to the anthropometric characteristics of employees. The operation of machinery and tools should be simple, avoiding the use of overly bulky or complex equipment. A balance must be maintained between job requirements, technical factors, and human capabilities. This approach helps to prevent occupational accidents and minimize damage caused by employee errors.
      • Fatigue prevention: Design the work area to match workers’ visual range; establish reasonable work and rest schedules to avoid mental stress, nervous tension, and visual fatigue.
      • Musculoskeletal injury prevention: Identify forces acting on muscles, bones, and joints in the lower back area and ensure that when designing lifting and carrying tasks, these forces do not cause harm or injury to the musculoskeletal system. Eliminate or reduce unfavorable working postures that may cause cumulative injuries. Avoid repetitive manual tasks during a single work shift to reduce cumulative injuries such as tendonitis, epicondylitis, tenosynovitis, and carpal tunnel syndrome.
    • Dust
      • In the event of an incident, these systems can release large quantities of air pollutants such as dust, carbon monoxide (CO), sulfur dioxide (SO₂), and nitrogen oxides (NOx), leading to air and water pollution that affects the regional and surrounding ecosystems and poses health risks to humans. Additionally, depending on local conditions, it is necessary to assess the likelihood of flooding during the rainy season, which may cause secondary pollution due to stormwater runoff (overflow of wastewater, blockage of drainage systems). The types of environmental impacts mentioned above, after consideration and assessment, will be summarized in a matrix table forecasting the level of impact from activities during both the construction and operational phases of the project.
    • Lighting
      • Workshops and production areas for processing leather, feathers, silk, and dyeing must be adequately illuminated.
      • Insufficient lighting increases the rate of defective products, reduces labor productivity, and raises the risk of occupational accidents.
      • Proper lighting protects vision, prevents fatigue, reduces occupational accidents and occupational diseases, and enhances productivity.

  2. Supervision of leather, feather, silk, and dyeing production processes

  • Cleaning, tidying, and disposal
    • The production and processing of leather, feathers, silk, and dyeing generate a large amount of dust accumulating on machines, equipment, workbenches, and walls. Therefore, use vacuum cleaners and washing methods to clean the workplace, collect and store waste and hazardous waste for management and treatment in accordance with legal, corporate, and factory regulations.
    • General principles to follow when disposing of waste:
    • Do not discard waste (containers, packaging contaminated with hazardous substances, etc.) indiscriminately; all waste products must be stored in designated hazardous waste containers with proper labeling.
    • Ensure that the disposal of chemicals poses no risk to humans or the environment.
    • Waste storage sites from the production process must be located in areas that meet current legal safety standards.
    • It is best to use licensed companies or individuals specializing in waste treatment for disposal.
  • Exposure monitoring
    • Work environment monitoring must be carried out regularly or periodically according to current regulations. Implement measures to improve working conditions and minimize the effects of hazardous factors, especially in environments containing hazardous chemicals.
  • Medical supervision
    • Periodic health checks help detect early symptoms of occupational diseases and assess the effectiveness of current chemical control measures.
    • Do not employ individuals with chronic infectious diseases or allergies in environments with hazardous chemicals.
  • Record keeping
    • All health and environmental records must be properly stored and maintained in accordance with regulations.
  • Training and occupational safety training
    • Workers involved in leather, feather, silk, and dyeing production must be trained in safety knowledge to competently perform assigned tasks. The basic training and education content should include:
    • Understanding laws and legal regulations regarding the production and processing of leather, feathers, silk, and dyeing.
    • Understanding and following production and processing procedures.
    • Understanding and properly using personal protective equipment and safety devices in leather, feather, silk, and dyeing processes; knowing how to select appropriate personal protective equipment according to work requirements and quality standards.
    • Maintaining proper personal hygiene standards and knowing how to safely decontaminate, wash, and change protective clothing.
    • Properly storing documents and records as required.

  ---

  II. PREVENTIVE MEASURES

  1. Enclosing or isolating sources of dust, waste, and hazardous chemicals

  • Define the distance or barriers between workers and production areas involving leather, feathers, silk, and dyeing to prevent exposure to hazards that threaten life and health.
  • Enclose entire machines or dust-generating sources, or cover entire production processes to prevent the spread of harmful vapors or toxic gases into the working environment. Alternatively, relocate the production stages to safe areas away from workers.

  2. Ventilation in leather, feather, and silk industry safety documents

  • When the production area involves volatile chemicals or dust generation, ventilation is considered the most effective control method after substitution or enclosure. Appropriate ventilation systems prevent the release of dust, vapors, or toxic gases by channeling them into ducts leading to treatment systems for detoxification before discharge into the environment.
  • Common ventilation methods include:
    • Local ventilation system: Delivers clean and cool air directly to fixed workstations where harmful gases and heat are concentrated.
    • General ventilation system: Operates on the principle of diluting contaminated air by introducing fresh air from outside and removing polluted air from inside (forced ventilation using pumps, fans, etc.), or by natural air exchange through windows, doors, or building design. Forced ventilation is more effective than natural ventilation because it allows control of hazardous chemical and dust concentrations.
  • General ventilation should only be used for less toxic, non-corrosive substances in small quantities.
    • Combine both local and general ventilation methods where possible.

  3. Personal protective equipment in leather, feather, and silk industry safety documents

  • Respiratory protective equipment
    • Gas-filtering respirator:
      • This respirator has two parts: the first consists of compacted cardboard layers to trap dust and moisture, and the second contains absorbent materials (typically granular activated carbon impregnated with specific chemicals) to filter toxic gases.
      • This respirator may only be used where oxygen levels are not below 16 percent and gas concentrations do not exceed specified limits (typically less than 2 percent). It is convenient for work, but has limited use duration and storage life for the filter cartridge.
    • Respirator with external air supply hose:
      • This type uses a rubber hose to draw clean air from outside, either passively or with a pump. It can be used in environments with varying levels of toxicity but limits user movement due to the hose length.
    • Oxygen tank respirator:
      • In this system, exhaled air passes through a one-way valve and a chemical absorber for carbon dioxide (CO₂), then mixes with oxygen from a tank to provide breathable air.
      • The limitation is that the oxygen tank is heavy, cumbersome, may pose fire or explosion risks, and reduces the wearer’s ability to hear external sounds.
  • Eye protection
    • Protective goggles are essential in production workshops and chemical laboratories, especially when handling acids, alkalis, or operations that produce dust, solid fragments, or liquid splashes.
    • Workers involved in dye mixing should not wear contact lenses due to the risk of chemical splashes.
  • Skin protection
    • Protective clothing
      • Protective workwear should be made from suitable materials resistant to the chemicals used, durable yet flexible. Avoid dark-colored clothing because it absorbs heat and increases discomfort. Protective clothing provides temporary protection (a few hours).
    • Gloves
      • Each type of glove protects against specific solvents. After prolonged use, gloves lose their protective capacity, allowing solvents to penetrate.

  4. Improving the working environment in leather, feather, and silk industry safety documents

  • Regularly inspect air quality in production areas, focusing on toxic gases such as CO, NOx, SO₂, H₂S, HCl, and dust, as well as solvent vapors, acids, alkalis, and chlorine specific to each production area.
  • Periodically test and analyze wastewater and supply water quality, especially for drinking and domestic use.
  • Plant trees and improve infrastructure conditions including electrical networks, pathways, and drainage systems.
  • Organize workplaces to ensure visibility of information, controls, and labels (clear Vietnamese signs to avoid confusion and prevent accidents).
  • Maintain workshop cleanliness.
  • Workshop sanitation reduces workplace pollution and should be performed after working hours or during maintenance breaks. In continuous three-shift operations, cleaning is done periodically along with machine maintenance. Depending on workplace conditions, sanitation goals may vary, for example:
    • Moisture control: Proper floor slopes and drainage to prevent standing water or leaks.
    • Dust control: Frequent vacuum cleaning.
    • Slip and contamination prevention: Regular washing of floors and equipment.
    • Disinfection: After general cleaning, disinfect and sterilize work areas.

  ---

  CHAPTER IV: SAFETY TECHNIQUES IN LEATHER, FEATHER, SILK, AND DYEING PRODUCTION

  I. SAFETY TECHNIQUES IN LEATHER, FEATHER, AND SILK PROCESSING

  1. Workshops and production areas for leather, feather, and silk processing

  • Workshops must comply with national technical standards and regulations, suitable for the nature, scale, and technology of leather, feather, silk, and dyeing production.
  • Workshops and warehouses must have emergency exits clearly indicated with signs and lighting, designed for safe evacuation and rescue during emergencies.
  • Ventilation systems must meet regulatory standards.
  • Lighting systems must comply with regulations for production and chemical storage; electrical equipment in areas with flammable or explosive chemicals must meet fire and explosion prevention standards.
  • Floors in dye preparation areas must be chemical-resistant, non-slip, durable, and properly drained.
  • Workshops and storage areas for materials must display safety regulations and hazard warning signs showing chemical identifiers, pictograms, signal words, and hazard statements. Where chemicals have multiple hazards, all must be displayed. Specific safe operating procedures should be posted prominently.
  • Lightning protection systems must be installed and inspected periodically as required.
  • Outdoor chemical tanks must have containment barriers or equivalent safety measures to prevent leakage and must include fire, explosion, and lightning protection.
  • Workshops and warehouses must meet fire prevention, environmental protection, and occupational safety requirements.
  • Outside the warehouse, post clear red warning signs “No Fire” and “No Smoking”, and fire extinguishing symbols at visible locations.
  • Chemicals and raw materials must be stored in accordance with national technical standards to ensure safety and allow for emergency response.
  • When stacking chemicals in storage, the following safety rules must be observed:
    • Bagged goods must be placed on pallets at least 0.5 meters from walls; moisture-sensitive chemicals must be raised at least 0.3 meters above ground.
    • Liquid chemicals in drums and gaseous chemicals in pressure cylinders must be arranged according to regulations.
    • Stacks must not touch the ceiling and must not exceed 2 meters in height.
    • Main aisles must be at least 1.5 meters wide.
    • Do not exceed floor load capacity.
    • Do not store used packaging or flammable materials inside the warehouse.
    • Inspect goods regularly for ventilation and moisture control; ensure bottom layers are not compressed or damaged.

  2. Distinguishing artificial and natural feathers in leather, feather, and silk industry safety documents

  • There are two types of feather materials on the market: natural and artificial feathers.
  • Natural feathers are made entirely from poultry feathers, have high prices, and are limited in quantity. They easily absorb water and cannot be washed. When burned, they emit a distinct smell similar to burnt hair.

  

  Artificial feathers are synthesized from chemical substances. They are much cheaper than natural feathers due to mass production. When burned, artificial feathers melt and stick together like plastic, are water-resistant, and can be washed.

  3. Cleaner production in the leather and feather industry in leather, feather, and silk safety documents

  

  4. Hydrolyzed feather meal production process in leather, feather, and silk safety documents

  • Hydrolyzed feather meal production process:
  • Poultry feathers cannot be used as a protein source without hydrolysis to break disulfide bonds, which are responsible for the unique structure of keratin fibers.
  • Various methods exist to convert keratin-rich materials into digestible hydrolyzed keratin protein, including hydrothermal, thermochemical, and biotechnological techniques. Biological hydrolysis uses keratin-degrading microorganisms (keratolytic microorganisms) or their enzymes such as keratinase, typically derived from Bacillus, Chryseobacterium, and Pseudomonas. Among these, Bacillus licheniformis has shown the best performance. Using bacteria and enzymes for feather hydrolysis is environmentally friendly and yields high-quality, digestible, and bioavailable hydrolyzed keratin, preserving essential amino acids. However, the process is costly due to long bacterial activity time and expensive enzyme production.
  • Most industrial keratin hydrolysis processes use the hydrothermal method, in which feathers are cooked under high pressure and steam to break disulfide bonds. The resulting hydrolyzed feather meal is highly palatable and digestible for livestock and poultry. It contains high levels of sulfur-containing amino acids. Hydrolyzed feather meal should have at least 70 percent digestible protein when analyzed by pepsin digestion.
  • Poultry feathers are collected from markets or slaughterhouses, analyzed for amino acid composition before and after processing. Hydrolysis reduces cystine content from about 8.8 percent to 3.6 percent, while other amino acids remain stable. Depending on raw materials and processes, the final product color ranges from yellow to dark brown. The hydrolysis stage is crucial for determining quality. Temperature, pressure, and duration influence results. Typically, feathers are treated at 115–145°C, then pressed to remove water and dried with steam at 150°C for 90–120 minutes before grinding, sieving, and packaging. Nutrient composition may vary depending on factory processes.
  • Nutritional composition and value of hydrolyzed feather meal in animal feed:
  • Feather meal’s feed value depends not only on protein content but also on energy levels. Proper energy-to-protein ratios are essential; overestimation of energy may cause excessive fat accumulation. Energy levels depend on chemical composition, especially fat content.
  • Feather meal can be effectively used in livestock diets when amino acid balance is considered. Without balancing, high inclusion rates may negatively affect productivity. For example, replacing too much corn protein with feather meal protein can cause lysine imbalance, reducing growth performance.
  • Although feather meal has long been used as a low-cost protein source that helps reduce slaughterhouse waste pollution, more research is needed to determine optimal inclusion rates for different animals. Therefore, not only protein but also fat content, energy level, and amino acid balance must be considered to ensure economic efficiency in livestock production.

  5. Production activities of leather and feather products in the leather, feather, and silk industry safety document

  • Feather garments and accessories,
  • Leather and feather accessories such as sheets, liners, strips, etc.
  • Other by-products from leather and feathers such as carpets, cushions, and industrial polishing pads.

  ---

  II. SAFETY TECHNIQUES IN DYEING WORK

  1. Workshop and Dyeing Area

  A reasonable overall site layout for the project should be planned based on environmental considerations such as:

  • Selecting a suitable direction to make the best use of natural ventilation conditions, contributing to improving the working environment inside the factory.
  • Determining the dimensions of industrial hygiene isolation zones between construction items within the factory as well as between the factory and residential areas to ensure ventilation between buildings, limit the spread of pollution, ensure fire prevention and fighting, and minimize the direct impact of waste on humans and surrounding structures.
  • Rationally arranging production stages, auxiliary areas, warehouses, and administrative areas with green buffer zones, maintaining a reasonable ratio of green area to total land area used for the project (possibly up to 20–25%).
    • The exhaust systems and chimneys of the factory should be placed in locations convenient for monitoring and treatment. (Department of Appraisal and Environmental Impact Assessment – 2009)
    • Power station areas, centralized wastewater treatment, and waste treatment facilities should be located downwind from the prevailing wind direction.
    • Isolate the boiler area from the production area to avoid convective heat transfer and ensure occupational safety in the production workshop. – Install cooling fans and ventilation systems in areas with heat generation and where workers are concentrated.
  • Install roof hoods and fans where necessary to extract heat, moisture, toxic gases, and dust from the production area.
  • Construction equipment must meet noise level standards according to Vietnamese Standard 5949:1998. Transport vehicles and construction machinery must be licensed by the Department of Inspection.
  • Construction routes near residential areas are only allowed to operate within regulated hours, avoiding quiet times such as noon or nighttime.
  • Regulate that high-noise vehicles and machinery such as pile drivers, excavators, and loaders must not operate during rest hours or simultaneously.
  • Construction vehicles and machinery must be regularly maintained and lubricated.
  • Limit horn usage and reduce vehicle speed when passing through residential areas and within the construction site.
  • Install, maintain, and regularly inspect noise-reducing devices or build soundproof walls around high-noise areas (such as electric machines, air compressors, excavators, bulldozers, road rollers, or mobile concrete mixing stations).
  • Arrange transport and movement routes logically, avoiding routes crossing residential areas. Prohibit transport and high-noise construction work at night (from 22:00 to 06:00). Reduce speed when passing through residential zones. (Department of Appraisal and Environmental Impact Assessment – 2009)
  • Minimize noise at the source of pollution by designing soundproofing components, installing noise-control equipment, and providing personal protective gear such as ear muffs or plastic earplugs for workers in high-noise areas.

  2. Dyeing Technology in the Occupational Safety Document for the Silk and Feather Processing Industry

  Dyes are a general term for colored organic compounds, highly diverse in color and type, which have the ability to impart color by attaching directly to fabric. Depending on their structure, properties, and applications, dyes are classified into various types.

  • Types of dyes used:
    • Direct dyes: also known as substantive dyes, are water-soluble color compounds that can color cellulose fibers through adsorption forces in neutral or alkaline environments. The optimal dyeing temperature ranges from 75°C to 95°C for 60–90 minutes.
    • Acid dyes: water-soluble dyes used mainly for dyeing wool and silk in an acidic environment. Negatively charged dye ions bond to positively charged fiber ions via ionic or salt linkages.
    • Reactive dyes: color compounds containing atomic groups that form covalent bonds with fibers. The pH value for color fixation is approximately 10.
    • Basic dyes: color compounds, mostly chloride, oxalate, or organic base salts. They dissolve in water and dissociate into colored cations and colorless anions. In terms of ionic characteristics, basic dyes are opposite to acid dyes.
    • Vat dyes: organic compounds insoluble in water with the structure R = C = O. When reduced, they become soluble in alkali and strongly absorbed by fibers. These dyes are easily hydrolyzed and oxidized back to their insoluble form, hence the name “vat dyes.” They are used for dyeing cellulose fibers or cellulose components in blended fabrics. They are not suitable for wool or silk since the alkaline conditions (high pH) during dyeing damage these fibers. Soluble vat dyes were later developed for easier dyeing, performed in neutral environments, with color developed under oxidation, often used for silk dyeing.
    • Disperse dyes: color compounds insoluble in water, mainly used for hydrophobic synthetic fibers.
    • Sulfur dyes: compounds insoluble in water but soluble in sodium sulfide (Na₂S) alkaline solution, similar to vat dyes. They have affinity for cellulose fibers and are also easily hydrolyzed and oxidized back to insoluble form, producing soft-textured dyed fabrics.
    • Pigment dyes: include some insoluble organic dyes and colored inorganic substances such as oxides and metallic salts. Pigments are typically used for printing and require polymeric binders to adhere to fabric since they have no fiber affinity.
    • Optical brighteners: neutral organic compounds that are colorless or pale yellow with fiber affinity. They absorb ultraviolet rays and emit blue-violet fluorescence, neutralizing yellowish tones on the fabric, giving it a bright white and bluish fluorescent appearance.
  • Scope of dye usage:
    • Different dyes are suitable for specific fabric types. For hydrophilic materials, water-soluble dyes are used, attaching to fibers through physical-chemical forces (direct dyes), ionic bonds (basic or acid dyes), or covalent bonds (reactive dyes). For hydrophobic synthetic materials, insoluble dyes (disperse dyes) are used.
      • Cotton fibers: reactive dyes, direct dyes, and soluble or insoluble vat dyes are commonly used.
      • Polyester fibers (PE): typically dyed with disperse dyes.
      • Blended fabrics: can be dyed in two separate stages or a single combined process:
        • Stage 1: disperse dyeing
        • Stage 2: reactive dyeing
        • Single-bath method: combination of disperse and direct dyes.
  • Printing and post-printing technology:
    • Printing technology mainly uses three types of dyes: reactive, pigment, and disperse. After printing, the fabric is heat-fixed:
      • Reactive dyes: 150°C for 5 minutes.
      • Pigment dyes: 140–150°C for 3 minutes.
      • Disperse dyes: 215°C for 1 minute.
    • To remove impurities or printing paste residue, washing is carried out as follows:
      • Reactive dyes: 4 washes
      • Pigment dyes: 2 washes
      • Disperse dyes: 2 washes
  • Finishing technology:
    • In addition to mechanical finishing, chemical treatments are applied using standard finishing solutions.
      • 100% cotton printed fabric:
      • Finish KVS 40 g/l: anti-wrinkle and crease-resistant
      • Ceramine HCL 10 g/l: fabric softener
      • Slovpon N 0.1 g/l: improves chemical absorption
    • PE/Co printed fabric:
      • Polysol S5 1 g/l: anti-wrinkle and crease-resistant
      • Repellam 77 10 g/l: softener for fabric and polyester fibers
      • Slovapon NN 5 g/l: softener for cotton fibers
      • Slovapon N 0.1 g/l
    • 100% cotton dyed fabric:
      • Finish PU 20 g/l
      • Catalyst PU 1 g/l: catalyst to harden PU finish
    • PE/Co dyed fabric:
      • Soft finish: same as PE/Co printed fabric
      • Repellan HYN 40 g/l: fatty compound forming soap, softening fabric
      • Al₂(SO₄)₃ 2 g/l: soap-forming agent
    • For cotton prints with small dyed areas requiring enhanced whiteness:
      • Leucophor BFB 2 g/l: optical brightener
      • Cibacron B Blue 0.02 g/l: reactive dye

  3. Dyeing Wastewater Treatment Methods in the Occupational Safety Document for the Silk and Feather Processing Industry

  • Standards for controlling wastewater pollution:
    • Ecological indicators
    • The pollution level of dyeing wastewater is evaluated based on ecological indicators or parameters.
    • The general ecological indicators used to analyze and assess pollution levels in dyeing wastewater are Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD). These two quantities measure the total oxidizable substances in the wastewater and are the most characteristic indicators for assessing dyeing wastewater pollution.
    • Biochemical Oxygen Demand (BOD) is the amount of oxygen consumed by microorganisms to oxidize organic compounds in the absence of light under standard temperature and time conditions. BOD values are expressed in grams or milligrams per unit volume, reflecting the amount of decomposable organic matter present in the sample.

  BOD (mg/l)	Water Quality
  1–2	Excellent
  3–5	Moderate
  6–9	Fairly Polluted
  >10	Highly Polluted

   

  • • Chemical Oxygen Demand (COD) is the amount of oxygen, measured in milligrams (mg), required to oxidize organic compounds present in one liter of water. The COD value is expressed in grams (g) or milligrams (mg) of O₂ per unit volume. Currently, a strong oxidizing agent such as potassium dichromate (K₂Cr₂O₇) is commonly used to determine Chemical Oxygen Demand because it can oxidize up to 90% of organic substances.
  • Other equally important groups of indicators
    • Additional ecological parameters
      • Heavy metal content: Metals from sources such as dyes, industrial chemicals, and auxiliaries, including copper (Cu), nickel (Ni), lead (Pb), chromium (Cr), cobalt (Co), zinc (Zn), and mercury (Hg), are often present in textile dyeing wastewater. Therefore, the concentration of heavy metals is an essential supplementary ecological parameter that must be analyzed. In addition, metals may enter wastewater from pipelines and even from supply water.
      • Organic halogens, abbreviated as AOX (Adsorbable Organic Halogen). AOX in textile dyeing wastewater originates from certain auxiliaries, dyes, and the use of chlorine for bleaching.
      • The color of dyeing wastewater is sometimes very intense. It obstructs sunlight penetration into the water, adversely affecting the ability of microorganisms to decompose organic substances and creating an aesthetically unpleasant appearance. Although color is not included in industrial wastewater standards in our country, it should be considered among the supplementary ecological parameters when evaluating textile dyeing wastewater pollution.
      • Another important group of parameters that characterize textile dyeing wastewater includes ecotoxicological indicators or the toxicity levels to aquatic species. These indicators assess the harmful effects of wastewater on aquatic animals and plants.
      • Aquatic toxicity is usually evaluated through the following four parameters:
    • Toxicity to microorganisms IC₁₀ – the concentration that inhibits 10% of microorganisms (Inhibition Concentration – 10%).
      • Toxicity to fish LC₅₀ – the concentration that causes 50% mortality (Lethal Concentration – 50% mortality).
      • Daphnia and algae EC₅₀ (Effective Concentration – 50% effect).
      • Toxicity to microorganisms (bacterial toxicity) and toxicity to fish are two characteristic indicators representing the degree of textile dyeing wastewater toxicity.
      • In developed industrialized countries (such as Germany, Austria, Switzerland, etc.), there are specific “textile dyeing wastewater” standards due to the unique characteristics of this industry. In Vietnam, where the textile industry is rapidly developing, it is necessary to establish and promulgate textile dyeing wastewater standards with characteristic parameters as mentioned above.
  • Wastewater treatment systems
    • Treatment methods
      • Chemical treatment processes are used to adjust and neutralize wastewater pH levels and to apply coagulation and flocculation methods to remove dyes that are difficult to biologically decompose after biological treatment.
      • Biological treatment processes involve aerobic decomposition using suspended activated sludge to break down organic substances in wastewater.
  • Wastewater treatment process line:
    • Incoming wastewater → Coarse screen (SCR) → Pump pit → Fine screen (SCR) → Equalization tank → Mixing tank + reaction tank → Primary settling tank → Biological filter tank → Disinfection tank → Treated wastewater outlet.
    • The physicochemical method, specifically aluminum sulfate coagulation, is applied to treat dyeing wastewater in joint-venture factories such as Donatex, Textile Company No. 7, and others.
    • All wastewater treatment systems are designed, constructed, equipped, and technologically transferred by the Environmental Technology Center (ECO) of Tecapro Company (Ho Chi Minh City).

  

  • • All wastewater treatment systems are designed and managed by the Environmental Technology Center (ECO) under Tecapro Company (Ho Chi Minh City).
    • The treatment results achieved by this method include:
      • Significant reduction in total suspended solids (SS); the COD index decreases by approximately 40–50%, and similar reductions occur for other parameters.
      • Noticeable reduction in wastewater color.
    • However, as wastewater pollution levels increase, aluminum sulfate coagulation alone cannot achieve Class B discharge standards.
    • Wastewater treatment using a combination of physicochemical and biological methods is implemented at Choongnam Vietnam Textile Co., Ltd. (Nhon Trach, Dong Nai).
    • Pre-treated wastewater

   

  • • The wastewater is highly alkaline (pH 10–12), with COD up to 1700 mg/L and very dark coloration.
    • Diagram of wastewater treatment using the combined physicochemical and biological method at Choongnam Vietnam Textile Co., Ltd. (Nhon Trach, Dong Nai).
    • The treated wastewater meets Class B discharge standards with only slight color remaining. This is a relatively high-capacity and effective method.
    • The complex process consists of multiple stages: pretreatment, physicochemical treatment, aerobic biological treatment, and activated carbon filtration, as applied by Viet Thang Textile Company.

  

  • • In the pretreatment stage, wastewater is collected into a central pump system, then passed through filters and an equalization tank. Here, wastewater is stirred to create a homogeneous mixture. Due to high alkalinity, sulfuric acid (H₂SO₄) is used for neutralization to maintain pH within the permissible range.
    • Physicochemical treatment: after screening, equalization, and pH adjustment, wastewater is pumped into the coagulation device for flocculation and sedimentation. This step also removes residual reactive dye color from the wastewater.
    • The wastewater is then sent to the flotation device. Large flocs are removed using dissolved air flotation technology, which operates on the principle that billions of air bubbles are injected into the water and adhere to the flocculated particles. These air-attached flocs rise to the surface and are removed by scraping devices.
    • After coagulation and flotation, total suspended solids (SS) are reduced by approximately 70%, COD by 30–40%, along with corresponding reductions in BOD and color intensity.
    • Biological treatment: wastewater is processed using activated sludge to decompose biodegradable substances. Filtration devices separate sludge from treated water. The clean water is discharged, while the remaining sludge is recycled back into the wastewater treatment system.
  • Advantages and disadvantages of the above wastewater treatment systems
    • Advantages: The integrated wastewater treatment process ensures stable and consistent results.
  • Disadvantages:
    • High investment costs and large land requirements.
    • Relatively high operating costs if the entire system (including activated carbon filtration and complete decolorization using the special coagulant Colfloc RD from Ciba) is operated.
    • Generates a large amount of sludge.
    • In earlier treatment systems, neutralizing highly alkaline wastewater containing many reactive dyes with sulfuric acid (H₂SO₄) is a significant drawback that could cause adverse effects later.

  ---

  CHAPTER V: Additional References

  1. Occupational Safety Training Services – Group 3 Certification

  

  Occupational Safety Training for Group 3

  Rated 5.00 out of 5

  99,000 ₫

  ---

  2. Group 3 Occupational Safety Test

  • Group 3 Occupational Safety Multiple-Choice Test

  ---

  3. Price List for Occupational Safety Training Services

  • View Details