Flame Retardants for Cellulose Comparison

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Questions and Answers

What compounds can be used to enhance flame retardancy in m-aramid fibres during exhaust dyeing?

Silicone polymers

Polyurethane resins

Halogen/phosphorous compounds (correct)

Aluminum oxide

Which of the following fibres has an inherent flame retardancy due to its high decomposition temperature?

Acrylic

Polyester

Nomex® (correct)

Cotton

What happens to natural fibres during pyrolysis compared to synthetic fibres?

Natural fibres melt and synthetic fibres char

Natural fibres develop a lot of char while synthetic fibres can drip (correct)

Natural fibres become non-flammable while synthetic fibres burn

Both fibres ignite without producing char

Which type of textile applications might benefit from inorganic fibres like ceramic and glass?

Flame-resistant protective clothing Signup and view all the answers

What is a common issue with fibre blends that include natural and synthetic fibres in terms of flammability?

They exhibit worse flammability than either component alone. Signup and view all the answers

What is the LOI value of the 50/50 blend of cotton and polyester?

18 Signup and view all the answers

Which flame-retardant fibre blend demonstrates the opposite behaviour in terms of LOI values?

Modacrylic fibres with cotton Signup and view all the answers

What is a textile product where flame-retarding properties are particularly beneficial?

Fireblockers in various applications Signup and view all the answers

What is a significant requirement of the Modified THPC–urea finish?

Requires ammonia vapour drying Signup and view all the answers

Which flame-retardant finish has a lower odour problem?

Modified THPC–urea finish Signup and view all the answers

What is an advantage of the N-methylol phosponopropionamide finish over the Modified THPC–urea finish?

Fewer dyestuff restrictions Signup and view all the answers

What is a notable characteristic of the Modified THPC–urea finish in terms of production?

Preferably used for large production runs to minimize costs Signup and view all the answers

Which flame retardant process is effective at around 20% concentration for rayon?

Alkyl dioxaphosphorinane disulfide additive Signup and view all the answers

What is a characteristic of the flame-retardant treatment for cotton compared to rayon?

Rayon has focused research on viscose spinning bath additives Signup and view all the answers

Which process was developed specifically for wool fibres to reduce flammability?

Zirpro process based on hexafluoro zirconate Signup and view all the answers

Which of the following is true regarding N-methylol phosponopropionamide finish?

It does not require any licensing Signup and view all the answers

What effect do silicone-containing finishes have on thermoplastic fibres during burning?

They increase burning due to silicate residue. Signup and view all the answers

Which type of finish is reported to have a similar effect as silicone finishes on polyester?

Fluorocarbon finishes Signup and view all the answers

What is one of the main outcomes of using silicone finishes on thermoplastic fibres?

They prevent melting away from flames. Signup and view all the answers

How does the silicate residue influence the behaviour of thermoplastic fibres?

It prevents melting and increases burning. Signup and view all the answers

What kind of chemical processing does the silicate residue belong to?

Chemical processing Signup and view all the answers

Which outcome is NOT associated with silicone and fluorocarbon finishes?

Increased melting of fibres Signup and view all the answers

In relation to flame retardancy, which finish is crucial for preventing fibres from igniting easily?

Silicone-containing finishes Signup and view all the answers

What is a key factor for the effectiveness of flame retardant finishes according to the discussion?

Chemical composition of the finish Signup and view all the answers

What is a common issue with durable flame-retardant finishes on cotton fabric?

Loss of tensile strength Signup and view all the answers

Which of the following represents a particular concern regarding flame-retardant finishes?

Toxicity of combustion gases Signup and view all the answers

What must be carefully tested when combining flame-retardant finishes with other types of finishes?

Performance and compatibility Signup and view all the answers

Which compounds are noted for generating toxic by-products when used in flame-retardant finishes?

Polyhalogenated dioxins Signup and view all the answers

What does LOI stand for in relation to textile flammability testing?

Limit of Oxygen Index Signup and view all the answers

What is a responsibility of the fabric finisher when producing commercial flame-retardant fabrics?

Addressing flame-retardant durability issues Signup and view all the answers

Which LOI value indicates that a textile will burn easily in air?

20 Signup and view all the answers

What issue arises when applying flame-resistant modified fibers?

Increased flammability Signup and view all the answers

Which component's presence in wastewater is a toxicity problem associated with flame-retardant finishes?

Phosphorus, antimony, and zirconium compounds Signup and view all the answers

What is a significant factor in achieving reliable and repeatable results in flammability testing?

Adhering strictly to the testing protocol Signup and view all the answers

What is crucial for a flame-retardant fabric to meet legal performance requirements?

Thorough testing across all areas of the fabric Signup and view all the answers

What certification do most flame-retardant finished textiles fail to meet?

Öko-Tex Standard 100 Signup and view all the answers

Which factor can adversely affect the uniform application of flame retardants?

Pad roll pressures Signup and view all the answers

What must be identified and controlled to ensure uniform application of flame retardants?

Finish bath concentrations and drying Signup and view all the answers

What is an important consideration when introducing new finish components into production?

Laboratory evaluations must be completed Signup and view all the answers

What potential issue must be recognized when applying flame-retardant finishes to textiles?

Altered fabric physical properties Signup and view all the answers

Study Notes

Comparing Two Permanent Flame Retardant Finishes for Cellulose

Modified THPC–urea finish (Proban type): Has a demanding process including moisture control, ammonia vapour treatment, and oxidation.
Modified THPC–urea finish (Proban type): Smaller wash shrinkage, better stability to hydrolysis, somewhat better ripping strength, less odour bothering, also for fibre blends with small cellulose content, preferably for large production runs to minimise costs and machinery requirements.
N-methylol phosponopropionamide finish (Pyrocatex CP new type): Includes extra washing after curing and drying costs.
N-methylol phosponopropionamide finish (Pyrocatex CP new type): Softer handle, fewer dyestuff restrictions, brilliant shades, much less free formaldehyde development, shorter after-burning time, less smoke development, no license required, including corresponding restrictions and costs.

Flame Retardants for Rayon

Rayon can be flame retarded by processes developed for cotton.
A successful additive for rayon is based on an alkyl dioxaphosphorinane disulfide.
This additive is used at ~20% for effective flame retardancy.

Flame Retardants for Wool

Despite wool being inherently less flammable, flame-retardant treatment is usually necessary.
There is a well-known process called Zirpro, based on hexafluoro zirconate and titanate salts.
This process is applied by exhaustion and pad processes under acid conditions (pH < 3).

Flame Retardancy in Carpets

Flame retardancy in carpets is achieved by incorporating halogen-containing compounds and antimony trioxide into the latex backing.

Enhancing Flame Retardancy in Aramid Fibres

m-aramid fibres (like Nomex) have inherent flame retardancy due to their high decomposition temperature.
This inherent retardancy can be further enhanced by using certain halogen/phosphorous compounds during exhaust dyeing.

Other Inherently Flame-Resistant Fibres

Kevlar (p-aramid), PBI (polybenzimidazole), Basofil, Kynol (melamine or phenol formaldehyde condensates) and flame-retardant modified polyester and regenerated cellulose find use in protective clothing and other textiles.
Inorganic fibres like ceramic and glass can be incorporated into or used entirely for textile products.

Flame Retardancy in Fibre Blends

Blends of natural and synthetic fibres often exhibit worse flammability than either component alone.
Natural fibres develop char during pyrolysis while synthetic fibres often melt and drip when heated.
The blend's combination of thermal properties results in melted synthetic material being held in contact with the heat source by the charred natural fibre.
This acts as a candle wick allowing the molten synthetic material to burn readily.
This effect is demonstrated by the LOI values of cotton, polyester, and a 50/50 blend of both.
LOI is defined as the oxygen content in an oxygen/nitrogen mixture that keeps the sample at the limit of burning.
Textiles with lower LOI values burn easily in air, while those with LOI values much higher than 20 will not burn.
There are exceptions to this, like a blend of modacrylic fibres and cotton, which can raise the LOI.

Troubleshooting for Flame Retardant Finishes

Legal implications in selling flame-retardant fabric require rigorous testing to guarantee performance requirements.
Uniform application of flame retardants is crucial to meeting these requirements.
Pad-applied finishes require identification and control of factors influencing uniformity, such as pad roll pressures, finish bath concentrations, and drying uniformity.
Exhaust and pad applied finishes are susceptible to flammability deterioration from softeners, lubricants, and other components.
Side effects on fabric properties must be recognized, often due to high application levels of flame retardants.
Harsh hand, loss of tensile strength, and colour effects (yellowing and dye shade changes) are common problems with durable flame-retardant finishes on cotton.

Toxicity Concerns

Toxicity of flame retardant components and combustion gases is a concern, especially in finishes based on halogens and heavy metals.
Halogenated compounds can generate polyhalogenated dioxins and furans.
Dust containing antimony oxide can pose a health risk.
Phosphorous, antimony, and zirconium compounds in wastewater can be problematic.
Halogenated organic flame retardants can end up in wastewater and are often slowly biodegradable.
Formaldehyde release during curing of permanent flame retardant finishes on cellulose and free formaldehyde in finished fabrics can occur during storage and transport.
Most flame-retardant finished textiles are excluded from the Öko-Tex Standard 100 label.

Other Considerations

Durability of the finish is often a problem.
Flame-resistant modified fibres offer an alternative but can introduce different problems.
Combination with other finishes containing flammable organic compounds can enhance flammability.
Silicone-containing finishes can prevent thermoplastic fibres from melting away from the flame, increasing burning.
Similar effects are reported for fluorocarbon finishes on polyester.

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Description

This quiz explores two different permanent flame retardant finishes for cellulose textiles: the Modified THPC–urea finish and the N-methylol phosphonopropionamide finish. It covers their processes, benefits, and various production considerations. Test your knowledge on textile treatments and flame retardancy!