Anti-mosquito finishing of textiles

Mosquitoes belong to the family Insecta, order Diptera, family Culicidae, and are small insects with a body length of 0.5cm~1.5cm, slender antennae, and mouthparts forming a long beak. The beak of female mosquitoes is generally suitable for piercing and sucking blood. Female mosquitoes need to suck blood to lay eggs and raise eggs. They have a keen sense of smell and are very sensitive to volatiles such as carbon dioxide and lactic acid produced by human breathing and metabolism. They can rush directly towards blood-sucking targets from 30 meters away. When mosquitoes bite, in order to prevent blood coagulation, they will inject some saliva into the wound after biting people and animals, and the pathogens are spread from there. Common mosquito-borne diseases in China include malaria, filariasis, dengue fever and Japanese encephalitis. Mosquito-borne diseases such as yellow fever, West Nile fever, Eastern equine encephalitis, Western equine encephalitis, Venezuelan equine encephalitis, St. Louis encephalitis and chikungunya are also prevalent abroad. In Asia, Africa and the Americas, more than 1 million people die from malaria every year due to mosquito bites. Therefore, mosquito control work is of great significance.

Currently, there are two main methods used to prevent mosquitoes that are relatively mature. The first method is to repel or kill mosquitoes in the environment, but the effect of this method is not long-lasting and the agent released by the aerosol will cause certain harm to the human body, so it is not suitable for regular use. The second method is to process textiles that are often in contact with the human body so that they have a more durable mosquito-repellent effect. After long-term production practice, this method has been proven to have a good anti-mosquito effect, is resistant to multiple washings, and is non-toxic and harmless to the human body.

Anti-mosquito finishing is to treat fabrics with microcapsules containing various mosquito repellents and insecticides. Under specific process conditions such as temperature and time, the microcapsules are combined with fibers through adhesives, etc., and the fibers are A mosquito repellent film insoluble in water and general organic solvents is formed on the surface. This kind of medicine film can emit an odor that mosquitoes and flies are disgusted with, so that mosquitoes are unwilling to stay on the fabric containing mosquito repellent and escape. At the same time, as soon as the mosquitoes come into contact with the fabric, they will be knocked down or killed immediately.

Natural repellents are generally based on plant-derived repellents, which are derived from the roots, stems, leaves, flowers, etc. of plants, and are mostly terpene esters, alcohols, and ketones. In the 1970s, terpenes extracted from plant essential oils had strong repellent activity against mosquitoes. A mosquito repellent was isolated from the essential oil of Eucalyptus camaldulum, which was found to have strong repellent activity against Aedes aegypti through bioassay. in recent years. The United States has conducted extensive research on natural source mosquito repellents and found two plants with high repellent activity: mulberry orange and false nepeta. Since the beginning of the 21st century, some people have conducted a repellent activity test on the methanol extract of the seeds of the Indigo tree, and found that it has strong repellent activity against individuals in all growth stages of Anopheles mosquitoes.

Natural repellents have many advantages, such as low toxicity or non-toxicity, no burning sensation on the skin, fresh smell, no drug residue after use, easy degradation, no pollution to the environment, etc. However, they are highly effective in repelling mosquitoes. and durability are generally lower than synthetic repellents.

Synthetic repellents mainly include organic esters, aromatic alcohols, unsaturated aldehydes and ketones, amines and amides, etc. In 1929, the mosquito repellent oil DMP (dimethyl phthalate) was successfully developed; in 1937, mosquito repellent was patented; in 1939, mosquito repellent alcohol (2-ethyl-1,3-diol) was launched. In 1956, the United States discovered DEET, a repellent with excellent broad-spectrum properties.

There are currently five types of synthetic repellents available for skin and fabric treatments:

(1) DEET (N,N-diethyl-m-toluamide, N,N-diethyl m-toluamide), also known as “DEET” in Chinese, is insoluble in water and soluble in alcohol, ether, isopropyl alcohol, and chloroform. , carbon disulfide, alcohol, benzene, propylene glycol, cottonseed oil, ketones and petroleum extracts and other organic solvents, slightly soluble in petroleum ether and glycerin, and the usage amount is 5% to 100%. The exact mechanism of action of DEET is currently unclear. It may be that it blocks the antennae of insects or lubricates the skin, or it may form an isolation layer on the skin to prevent insects from biting or staying. But in recent years, researchers have discovered that DEET can cause neurological diseases, encephalopathy, and skin diseases. Therefore, DEET has been used with caution, and the use of DEET has been banned in Thailand and Taiwan.

(2) Picaridin (KBR 3023, isobutyl hydroxyethyl piperidine carboxylate) is a colorless liquid with a vapor pressure of 5.87×106 Pa at 25°C, a boiling point of 296°C, and a melting point of -170°C.

(3) Oil of Lemon Eucalyptus/PMD (paramenthane-3,8-dio, l-menthane-3,8-diol, lemon eucalyptus oil extract) has a strong lemon aroma , has a grassy aroma similar to citronella oil, and is a colorless to light yellow transparent oily liquid.

(4) IR3535 [3-(N-butyl-N-acetyl)-aminopropionic acid-ethylester, Chinese alias Yimoning] is an ester compound. Compared with amide repellents, it has a pleasant aroma and is not irritating to the skin. , has gradually become a research hotspot. The structure of IR3535 is similar to alanine, and its toxicity and environmental hazards are less than DEET. It has the advantages of no toxic side effects on skin and mucous membranes, no allergies, and no skin permeability. It is very safe to use. IR3535 was used in Europe for 20 years and became available in the United States in 1999. Synthetic repellents used only for fabric treatment include permethrin (also known as permethrin, Chinese alias permethrin). Permethrin is soluble in acetone, ethanol, ether and xylene, etc. Organic solvent, the solubility in water at 25℃ is (0.07±0.02) mg/kg, it is stable to acidic media and light, and can be hydrolyzed in alkaline media. Its relative density is 1.214 (25℃) and its refractive index is 1.5627 (25℃).

(5) Cyclodextrin is made from starch through fermentation and degradation. Cyclodextrin molecules have a cyclic configuration and have a hydrophobic inner cavity, as shown in Figure 1. This hydrophobic lumen can store gases and non-polar organic substances. Since the inner cavity of the cyclodextrin molecule is non-polar, non-polar molecules or molecules with non-polar groups can be stored in the base. All known mosquito pheromones involve organic molecules with a non-polar part, so they can form complexes with cyclodextrins.Therefore, textiles with long-lasting fixed cyclodextrin can play a passive protective role against mosquitoes and can significantly reduce the total amount of pheromones in the air around the human body.

Pesticides mainly kill pests through contact, gastric poisoning or fumigation.

Pyrethrins are one of two esters extracted from pyrethrum and are used as insecticides. Pyrethroids are a type of non-volatile hydrocarbon compounds that have been rapidly developed in the past 40 years. They are a new type of insecticide that is artificially synthesized by simulating the chemical structure of natural pyrethrins. It has the characteristics of rapid knockdown, broad insecticidal spectrum, high efficacy, repellent effect on insects, low toxicity to human body, easy biodegradation, and does not produce toxic residues after biodegradation. However, there are also shortcomings such as most species being highly toxic to fish, poor selectivity to natural enemies, and having no systemic conduction effect.

Among pyrethroid compounds, Tetramethrin is suitable for anti-mosquito finishing of fabrics. Pure Tetramethrin is a white crystal, insoluble in water and soluble in organic solvents. It has a very fast knockdown effect on insects and should be stored at room temperature. Quality remains unchanged for 3 years.

At present, the anti-mosquito finishing processes mainly include dipping process and padding process.

(1) Impregnation process: dipping (bath ratio 1:10) → dehydration (liquid carrying rate 25% ~30%) → drying (80℃~100℃, 1 min ~3 min) → baking (120℃~130 ℃, 1 min).

(2) Padding process: padding with anti-mosquito finishing liquid (padding rate 70%) → drying (70°C~100°C, 3 min) → baking (110°C~120°C, 30 s).

The dosage of anti-mosquito finishing agent depends on the type of anti-mosquito finishing agent, fabric type and use.

At present, anti-mosquito textiles are cool and ventilated to wear, can prevent mosquito bites, do not require any pharmaceutical assistance, have no allergic reaction to the skin, are soft to the touch, comfortable to wear, have simple production technology, low cost, and are easy to mass produce. It can choose thermoplastic technology to make disposable clothing, or use textile technology to produce durable clothing; it can be made into a set of anti-mosquito clothing, or it can be made into anti-mosquito leg covers, headgear, and sleeves separately. This kind of clothing has various styles and is suitable for night workers, field workers, military, disaster relief, etc., and has promising sales prospects.