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Insect resist and mite protection

finishesinsect resist finishes, including protection against dust mites.

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Introduction• Insect resist finishes are chemical treatments that

protect wool and other animal fibres from attack by

• the larvae of certain moths • and beetles. Only keratincontaining

• fibres are damaged by these insects. • Dust mites cause health problems, such as

• allergy, • asthma • and neurodermitis.

• Mites are not insects, they belong to the• spider group of animals.

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INTRODUCTION• Keratin-digesting pests include

• the clothes moth (Tineola bissiella),• brown house moth (Hofmannophilia pseudoprettella),• carpet beetle (Anthrenus flavipes)• and fur beetle (Attagenus pellio).

• Moth populations can increase dramatically in a relatively short time. Each female moth lays

• about 150 eggs • and four to five generations per year can be

produced.

• Various chemicals have been used to control damage from larval attack on wool

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INTRODUCTION• Annually, about 2 million pounds weight (about

900 000 kg) of insect resist finishes are used• with wool products.

• The most important market for insect resist finishes is the carpet industry. • More than two-thirds of these finishes are used with floor

coverings and wall hangings.

• Other significant markets include • home furnishing • and upholstery fabrics, • Blankets,• uniforms, • apparel and furs.

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Mechanisms of insect resist finishes

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Mechanisms of insect resist finishes

• Insect resist finishes fall into two types, • poisons

• Poisons interfere with the keratin digesting process of the

• larvae • and nerve poisons that have been specifically

formulated from agricultural pesticides for textile applications.

• digestion-affecting poisons are more species specific, killing the feeding larvae by

• blocking enzymes needed for digestion.

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Mechanisms of insect resist finishes• Nerve poisons are more general control agents, affecting a

broader range of insects. Both types are considered to enter through the larvae‘s digestive tract

• because insect resist treated wool only kills insects that ingest the fibre

• Each category has distinct advantages and disadvantages. • Digestive poisons present a lower environmental hazard than nerve

poisons, but are not as effective against some pests such as • the brown house moth.

• Nerve poisons are usually more rapidly biodegraded than • digestive poisons, but also exhibit less durability.

• The usual application level of insect resist finishes varies • from 0.1 to 1.5 % on weight of goods• depending on the

1. final product,

2. the specific finish

3. and the performance requirements.

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Chemistry of insect resist finishes

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Chemistry of insect resist finishes

• Digestive poisons were the first durable insect resist finishes to be commercialised.

• Early products were based on • chlorinated tri- phenyl-methanes• And chlor-phenylids• a Later, sul-cofe-nurons• and flu-cofe-nurons were

introduced.• These compounds could, for the

most part, exhaust• To wool under acidic conditions

and have reasonable fastness properties.

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Chemistry of insect resist finishes

• Agricultural pesticides were found to be effective insect resist agents when applied in emulsion form to wool dyebaths.

• Dieldrin (Fig. 16.2a), one of the original nerve poisons, is also highly toxic to mammals and aquatic life and its use has been banned in most countries.

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Chemistry of insect resist finishes

• Products based on permethrin (Fig. 16.2b), a

• synthetic pyrethroid, are very effective against moth larvae,

• but have less effect on

Anthrenus beetles.

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• To overcome this disadvantage, combination products of

• permethrin and hexahydropyrimidine derivatives (Fig. 16.2c) have been introduced.

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Application of insect resist finishes

Insect resist finishes are most commonly applied during dyeing.

The best light fastness and wet fastness properties are obtained when the finish is able to fully penetrate the fibres.

When applying insect resist finishes to wool/nylon blends,care must be taken in the choice of the particular finish used.

Chlorphenylid derivatives exhaust preferentially to nylon, leaving the wool fibres unprotected,

whereas permethrin-based products distribute themselves more uniformly between the two fibre types.

Application of insect resist finishes during scouring is also possible when woolyarns for carpets are scoured in hank form or when fabrics for blankets, apparel andupholstery are prepared as piece goods. Finishes applied during scouring do notcompletely penetrate the fibres owing to the lower temperatures and shortertreatment times in the scouring process, so fastness properties are not as durable aswith finishes applied during dyeing.

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A third approach to the application of insect resist finishes is to combine the finish with spinning lubricants and then to apply the combination to loose woolprior to spinning.

This method of finish application produces yarns with only asuperficial treatment with much lower fastness than applications made duringdyeing or scouring.

Chemical cleaning of wool textiles as smaller carpets, wall hangings, upholstery fabrics, furs or uniforms can easily be combined with the

application of insect resist finishes.

Dip and cautious spray application is used for the protection of wooland silk textile exhibits

in museums.

Application of insect resist finishes

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Evaluation of insect resist

finishesStandard methods

for evaluating fabrics with insect resist finishes are given in AATCC

Test Method

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The efficiency of insect resist finishes can be determined by tests that measure theweight loss of the treated fabrics and/or the weight of insect excrement afterexposure to insects under controlled conditions.

The direct examination of exposed fabrics by microscopic methods to observe fibre damage is also useful.

The typical half round bite traces of the moth larvae are observable.

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Troubleshooting for insect resist finishes

• Exposure to light as well as mild washing, dry cleaning and shampooing can reduce the effectiveness of insect resist finishes significantly.

• The durability requirements of the final product must be carefully considered during product development.

• Finish baths that are not completely depleted of insect resist finishes must be

• disposed of in accordance with local, state and federal regulations.

• Special care must be taken to prevent accidental release of these insect poisons to the environment

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