Research progress on anti-mosquito textiles

Abstract: This paper reviews the main production methods of anti-mosquito textiles, the types, development status and existing problems of mainstream anti-mosquito repellents and insecticides, as well as the test methods for anti-mosquito effects. The application of some new technologies in the production of anti-mosquito textiles is introduced.

Many insects in nature, such as mosquitoes, flies, etc., can transmit diseases to humans by biting people or contaminating food. In Asia, Africa and the Americas, more than 1 million people die from malaria deaths from mosquito bites every year, seriously affecting people's health. Anti-mosquito textiles are a kind of hygienic protective textiles that evade or kill such insects. In recent years, textile pest control has gradually attracted attention at home and abroad, and has achieved relatively rapid development.

1 Production methods of mosquito-repellent textiles

1·1 pest control

Insect-proof finishing is the special finishing of textiles by using insect repellents such as mosquito repellents or insecticides. There are three main processing methods: the first one is made by using a repellent emulsion or a solution to impregnate the clothes; the second type First, the repellent emulsion or solution is impregnated with the clothes, and then the surface treatment is performed with the polymer compound, so that the formed film "seals" the repellent on the woven fabric; the third type is to first microencapsulate the repellent. The microcapsule anti-mosquito agent is processed and then the microcapsule anti-mosquito agent is firmly attached to the woven fabric by means of a microcapsule fixing agent or other interlinking agent. The first method is very effective, but it is not resistant to washing or raining; the latter two methods are not only very effective, but also have washability. In addition, the microcapsule type fabric anti-mosquito finishing agent can also be used in the same bath as the soft finishing agent, which is convenient and economical.

1·2 Insect fiber development

Anti-mosquito fiber is the first fiber developed by Japan to prevent insect bites such as mosquitoes. Such fibers are mainly produced by mixing a part of the main components of the pesticide in the production process of chemical fibers. At present, OLESET polyethylene monofilament insect-resistant fiber produced by Sumitomo Chemical Co., Ltd. has been certified by the World Health Organization and can be used to make malaria-resistant insecticide nets. The main production method is to add permethrin masterbatch in the process of spinning high-density polyethylene fiber, and the amount of permethrin accounts for 2% of the amount of high-density polyethylene fiber. Due to the large inter-molecular voids in the polyethylene resin, the permethrin in the fiber gradually migrates from the inside to the outside, covering the surface of the fiber; therefore, the surface of the fiber may be peeled off by washing or the like. However, when it is dried for about 4 hours in the sun, enough fiber will seep out on the surface of the fiber. The fiber is woven into a mesh cloth of 0·4 mm×0.4 mm, and the drug that the insect touches the fiber during use is destroyed by the drug [1].

2 commonly used insect-repellent finishing agents

The ideal anti-mosquito finishing agent should meet the anti-insect effect, good durability, safe and harmless, not easy to produce drug resistance, and does not affect the original performance of the fabric [2]. At present, the main anti-mosquito finishing agents are repellent and killing. Repellents can be divided into synthetic and natural types according to source [3-5].

2·1 natural repellent

The natural repellent is mainly a repellent for plant sources. It is an effective insect-repellent component extracted from some plant roots, stems, leaves and flowers with insect-repellent properties. Most of them are esters, alcohols and ketones of terpenoids. Object. In the 1970s, the terpene component extracted from plant essential oils had strong repellent activity against mosquitoes; a mosquito repellent isolated from red peony essential oil was found to have strong Aedes aegypti by bioassay. Repellent activity. In recent years, a large number of studies have been carried out on natural source mosquito repellents in the United States, and two high repellent active plants, mulberry orange and schizonepeta, have been found. Since the beginning of the 21st century, some people have carried out repellent activity tests on the methanol extract of neem seed, and found that it has strong repellent activity against mosquitoes in each growing period.

Natural repellents have many advantages, such as low toxicity or non-toxicity, no burning sensation on the skin, fresh scent, no drug residue degradation after use, no pollution to the environment. However, it is generally lower than synthetic repellents in terms of efficiency and durability of mosquito repellent.

2·2 Synthetic evasion agent

Synthetic repellents mainly include organic esters, aromatic alcohols, unsaturated aldehydes and ketones, amines and amides. In 1929, the mosquito repellent oil DMP (dimethyl phthalate) was successfully developed; in 1937, the mosquito repellent was patented; in 1939, the mosquito repellent (2-ethyl-1,3-diol) was introduced; in 1956, the United States discovered The repellent DEET (N, N-diethyl-m-toluamide, N,N-diethylm-toluamide) has an excellent broad spectrum. There are five synthetic repellents currently available for skin and fabric treatment:

(1) DEET Chinese alias "mosquito repellent", insoluble in water, soluble in alcohol, ether, isopropanol, chloroform, carbon disulfide, alcohol, benzene, propylene glycol, cottonseed oil, ketones and petroleum extracts, etc. Organic solvent, slightly soluble in petroleum ether and glycerin, its use is 5%~100% [6]. The exact mechanism of action of DEET is still unclear. It may be that it can block the insect's antennae or lubricate the skin, or it may form a barrier layer on the skin that hinders insect bites or stops. But in recent years, researchers have found that DEET can cause nervous system diseases, encephalopathy and skin diseases. Therefore DEET has been included in the caution, Thailand and Taiwan have been included in the ban.

(2) Picaridin (KBR 3023, isobutyl hydroxyethylpiperidinecarboxylate) is a colorless liquid having a vapor pressure of 5·87×10 6 Pa at 25 ° C, a boiling point of 296 ° C, and a freezing point of -170 ° C.

(3) Oil of Lemon Eucalyptus / PMD (paramenthane-3, 8-dio, 1-p-menthan-3,8-diol, lemon eucalyptus oil extract) with strong lemon aroma Flavor, there is a grassy fragrance similar to citronella oil, a colorless to pale yellow transparent oily liquid.

(4) IR3535 [3-(N-butyl-N-acetyl)·aminopropi-onic acid-ethylester, Chinese alias Imerin)] is an ester compound, which has a pleasant aroma compared to an amide repellent. Without stimulation, it has gradually become a research hotspot. The structure of IR3535 is similar to alanine. Its toxicity and environmental hazard are less than DEET. It has the advantages of no toxic side effects on skin and mucous membrane, no allergic and no skin permeability. It is very safe to use. The IR3535 has been in use in Europe for 20 years and was launched in the United States in 1999.

The synthetic repellent used only for fabric treatment is permethrin (Permethrin, also known as permethrin, Chinese name Baifening), soluble in organic solvents such as acetone, ethanol, ether and xylene, in water at 25 ° C. The solubility is 10.05~10·09 mg/kg; it is stable to acidic medium and light, and can be hydrolyzed in alkaline medium. The relative density is 1.214 (25 ° C) and the refractive index is 1.562 7 (25 ° C).

(5) Cyclodextrin It is prepared by fermentation degradation of starch. The cyclodextrin molecule has a cyclic configuration and has a hydrophobic inner cavity for storing gases and non-polar organics. Since the lumen of the cyclodextrin molecule is non-polar, non-polar molecules or molecules with non-polar groups can be stored in the matrix. All known mosquito pheromones are involved in organic molecules with non-polar moieties, and thus can form complexes with cyclodextrins, so that textiles with persistently fixed cyclodextrin have passive anti-ant effects and can be greatly reduced. The total amount of pheromones in the air around the human body [7].

2·3 insecticide

Insecticides mainly kill insects through contact, stomach poisoning or fumigation. Pyrethrin is one of two esters extracted from pyrethrum and can be used as an insecticide. Pyrethroids are a class of non-volatile hydrocarbon compounds that have developed rapidly in the past 40 years. They are a new class of insecticides that are artificially synthesized by simulating the chemical structure of natural pyrethrin. It has the characteristics of rapid knockdown, wide insecticidal spectrum and high efficacy. It has a repellent effect on insects, low toxicity to human body, easy biodegradation, and no toxic residue after biodegradation. However, there are also some shortcomings such as high toxicity to fish, poor selectivity to natural enemies, and no systemic conduction. Among the pyrethroid compounds, the most suitable for fabric anti-mosquito finishing is Tetramethrin. Is a white crystal, insoluble in water, soluble in organic solvents, the knockdown effect on insects is extremely fast, and the quality remains unchanged at room temperature for 3 years.

3 Anti-mosquito textile new technology

3·1 microcapsule technology

Microcapsule technology refers to the production technology of forming a continuous wrap layer on the outside by using solid particles, liquid droplets or gas as the core material of the capsule. Microcapsules protect substances from environmental influences, mask taste, color, odor, change material density, volume, condition or surface properties, isolate active ingredients, reduce volatility and toxicity, and control sustainable release. Therefore, the use of microcapsule technology to wrap anti-mosquito repellent or insecticide can effectively control the release rate of the active ingredient and achieve the purpose of sustained release, thereby prolonging the use time of the product.

The SPT microcapsules supplied by American International Perfume and Fragrance (IFF) contain natural organic ester vegetable oil with obvious mosquito repellent effect. Natural organic ester vegetable oil is an effective nerve numbing agent for insects that can cause insects to lose the ability to search for biting targets. According to relevant authoritative research institutions, this microcapsule finishing agent can reduce the frequency of mosquito bites from 50 beats/min to nearly zero [8].

3·2 nano resin bonding technology

Newly launched at the Burlington Laboratory in North Carolina, USA, using the Per Fly Zone repellent finisher No Fly Zone for durable bonding to fabrics. It utilizes the patented nano resin bonding technology to cross-link permethrin to polyester, nylon, cotton, wool or Nomex fibers, thus ensuring that the fabric can be resistant to 50 times of household washing [9].

4 Anti-mosquito textile testing standards

At present, there is no complete test standard for anti-mosquito finishing fabrics. It is impossible to directly test the fabrics after anti-mosquito finishing, so it can only be evaluated by reference to other relevant standards. There are two related standards that are internationally accepted:

(1) The method for determining the surface concentration and release of pyrethroid insecticide-treated nets discussed by the International Pesticide Analysis Collaboration Committee (CIPAC) in 2005 can be chemically tested.

(2) WHO/CDS/WHOPES/GCDPP/2005, recommended by the World Health Organization's Pesticide Evaluation Committee (WHOPES), can determine the washability and anti-mosquito efficacy of long-lasting insecticidal nets. In China, the main reference and reference to three standards drafted by the Ministry of Agriculture [10-12] are:

(1) GB13917·1-1992 “Method for determination of indoor efficacy of propellant for indoor registration of sanitary pesticides for rural registration”;

(2) GB / T 17322 · 10-1998 "Pesticide registration of pesticides for indoor efficacy evaluation of repellents";

(3) GB 13917·3-1992 “Indoor Pharmacodynamic Test Method for Pesticide Registration Hygiene Insecticides”

These standards can only test the effect of anti-mosquito finishing agents or raw materials, can not directly test the effect of anti-mosquito-finished fabrics, and the parameters such as washing fastness of anti-mosquito finishing fabrics and the application performance of finished fabrics after finishing. There are no relevant requirements for changes. In addition, the scope of application of these three test standards is also different, GB 13917·1-1992 is applicable to the determination of the efficacy of propellants, GB / T 17322 · 10-1998 applies to the evaluation of the efficacy of repellents, GB 13917 · 3-1992 is suitable for the evaluation of the efficacy of small smoke and smoke tablets.

5 Conclusion

Since the development of anti-mosquito textiles, the use of synthetic repellents has become the mainstream product in the market, and its anti-mosquito effect is better, but the harmful side effects on the human body can not be underestimated. At the same time, due to the good biocompatibility and degradability of plant-derived natural repellents, it has become a major trend in the future. Establishing a complete evaluation standard for anti-mosquito textile testing is also urgent for promoting the rapid development of such functional products.