Progress in finishing technology of the hottest si

Progress in silk fabric finishing technology

the excellent gloss, color and hand feel of silk fabrics must be highlighted and strengthened through reasonable and strict finishing. The most basic requirement in the finishing process is to ensure the silk feel and drapability of silk fabrics. In addition to forming a unique fabric style through finishing, the functional finishing of silk fabrics has become more and more important. These finishing methods to improve the performance of silk fabrics include: anti crepe, anti-static, water and oil repellent, flame retardant, dimensional stability, washable and wearable, fluffy and silky feeling. The washing and wearing properties of silk are becoming increasingly important, and appropriate softeners, elastomers and synthetic resins must be used to meet the requirements; Functional finishing of silk, such as stain resistance and flame retardancy, is the focus of functional finishing of silk fabrics; Another important area of silk fabric finishing is antibacterial finishing that can maintain hygiene and freshness

the improvement of the handle and appearance of silk fabrics is mainly achieved by mechanical finishing, while the functional finishing is achieved by chemical finishing

mechanical finishing

calendering: calendering can improve the hand feel and appearance of the fabric. Generally, silk fabrics adopt cold calendering, which can obtain a soft hand feel. Hot rolling light can make the fabric obtain better gloss, but the performance of the fabric is easy to be adversely affected. The common calendering equipment is Palmer or felt calenders, which should always check the cutting tools. It is mainly used for smooth plain crepe fabrics and twill Serge fabrics, such as poplin and silk

Cooking: cooking can give silk fabric dimensional stability, eliminate fabric wrinkles, and make the fabric feel smooth. In the relaxed state, the fabric is treated with superheated steam along the less hard felt. At present, intermittent cooking machines are mainly used, and continuous calenders with felt are also used

stretching: stretching can let the silk fabric dry through hot air at the same time, and pull the fabric to the set width. At the same time, through the combined action of heat or heat and other factors, give the fabric the required hand feel. In the early days, the calender used hot air to dry the fabric. Now, due to the use of various elastomers and resins, a baking oven with a temperature of up to 150 ℃ is required

packing: packing finishing can improve the optical appearance of silk fabrics. Silk is very sensitive to mechanical friction in various finishing processes. Even if the best preventive measures are taken, the silk fabric may still be scratched. In order to improve the optical appearance of the scratched part, it is necessary to apply a fine oil film evenly to both sides of the fabric, so that the scratch point is not easy to see, so as to improve the appearance of the fabric. In the early days, only the problematic fabric parts were manually padded. Now, the equipment that evenly distributes the oil on several oil feeding rollers is used to evenly apply fine oil film on the whole fabric

cloth rubbing: cloth rubbing finishing is mainly to give the fabric a soft feel, especially when the calendering effect is insufficient. At present, the scraper type cloth kneading machine is mostly used, and the fabric passes over the edge of the inclined scraper to complete the cloth kneading and finishing

steaming or preshrinking: using horizontal steaming machine or preshrinking machine to preshrink silk fabric can make the fabric shrink and relax

chemical finishing

weight gain: due to the removal of sericin, the silk will lose weight by 20%~50% after degumming. The weight gain of silk fabric can make up for the lost weight, give the fabric a fuller and fluffy feel and better filling performance, improve the drapability of the fabric, and give the fabric better washing and wearing performance. There are three methods of weight gain. The size of plant weight gain and mineral weight gain root should be based on the rules of shape and foundation map and grafting weight gain (polymer weight gain). At present, the most advanced method is the weight gain method of polymer "grafting", which makes the weight gain treatment very easy. The grafting weight increasing method mainly uses amine methacrylate and ammonium persulfate to treat silk fabrics, which can improve the dyeing performance of silk fabrics while increasing weight. However, at present, there is still a problem that it is beneficial to carry out grafting finishing before or after dyeing. At the same time, the grafting weight increasing method still needs to be further industrialized, and only a few manufacturers, such as twisted yarn manufacturers for silk ties, adopt this weight increasing method

softness: in order to obtain lasting softness of silk fabrics, chemical softeners must be used. The commonly used durable softeners are organic softeners and silicone softeners, including oil, wax and fat; Cations -- mainly imidazoline and ethoxy fatty amines; Anions -- sulfate or sulfonate such as stearic acid, organic acid, palmitic acid and fatty alcohol; Non ionic -- long chain alcohols, acids, glycerols, oil and waxy polyethylene glycol, polyethoxylates; Silicone lotion -- polydimethylsiloxane, polymethylhydrosiloxane, aminosilicon, etc; Polyethylene lotion. The current trend is to use epoxy derivatives of silicone, which can give the fabric softness, crepe resistance and yellowing resistance

antistatic: silk can be grafted with monomers to improve the electrostatic accumulation performance and reduce the amount of static electricity accumulated on the silk fabric. There are two kinds of antistatic agents. One is electrostatic eliminator, which is mainly used to improve the moisture absorption of the fabric. The silk fabric is treated with specific water-soluble ethylene monomers and specific acids, or specific metal particles are deposited on the fabric, or metallic silver coating is used, Can produce electrostatic elimination effect; The other is antistatic agent. Its action principle is to endow the fabric with antistatic property by reducing the friction between fibers and between fibers and metals. Generally, specific alkaline lubricants, such as metal oil and butyl stearate, are used

wrinkle resistance: compared with synthetic fibers, silk has poor easy care performance, so it is necessary to carry out good wrinkle recovery (CR) finishing on silk to improve its size. We pay special attention to the stability of the general trend of environmental and social development and the wrinkle recovery after washing. The existing anti wrinkle finishing agents include crosslinking agents, reusable urea formaldehyde pre shrinkables, Dihydroxymethyl dihydroxyethyleneurea, organosilicon, acrylate softeners and catalysts that increase the dry and wet wrinkle recovery performance. In addition, other anti wrinkle agents that can improve the dry and wet Cr, tear strength, elasticity and weight gain properties of silk fabrics include a variety of N-hydroxymethyl derivatives of nitrogen compounds and other finishing agents

waterproof and oil repellent: the principle of waterproof and oil repellent finishing is to reduce the surface energy of silk fabrics in the air, so as to prevent oil stains or oily contamination. Teflon is the most commonly used surface finishing agent for fabrics. Other important waterproof agents include aluminum compounds used alone or together with soap, wax dispersants, etc. when natural silk is grafted with hexafluoropropylene, vinyl fluoride, vinyl chloride and acrylonitrile steam, its waterproof Oil repellency, mineral acid resistance and light stability will be improved

flame retardant: silk has self extinguishing property, which is endowed by polyhalic acid reaction products with ring nuclei, such as chloromycelic acid and thiourea, but it still cannot safely pass the "vertical flame test", so it also needs flame retardant finishing. Titanium hexachloride, titanium tetrachloride and zirconium chloride can endow fabrics with good flame retardancy. Non ionic complexes of zirconium, titanium or tungsten can also be used as flame retardant finishing agents for silk fabrics. In addition, specific phosphorus compounds can also improve the flame retardancy of silk fabrics, and the crepe resistance and shrinkage are also improved

antibacterial: antibacterial finishing has become more and more popular in the finishing of silk fabrics. The main methods are to treat the fabrics by rolling, dipping or spraying. The finishing solution includes n- (2,2-dichloroethylene) salicylamide, 0.01%~0.25% solution, salicyl n-acylamide, dodecyl trimethylamine chloride, etc. phenolic compounds are widely used because of their moderate activity, It can be deposited on the surface of fabric in the form of lotion to form polymer film

light resistance: the chemical sensitivity of silk to light has always been one of the biggest obstacles to the application of silk, which is caused by ultraviolet radiation, that is, plants exposed to sunlight will absorb ultraviolet rays. Because the light stability of silk is very important for jobs, it is necessary to finish silk fabrics to prevent free radiation. At present, ultraviolet absorbers or light stabilizers are mainly used to finish silk fabrics, Such as phenyl ester and salicylate, but the development of this kind of finishing agent still needs further research

new finishing type of silk

aromatic finishing: aromatic finishing can prevent the odor generated by the fabric after long-term use, make the clothing emit a fresh smell, and endow the fabric with softness, especially suitable for towels, napkins, casual wear, etc

cool finishing: when applied to fabrics, this kind of finishing agent can give the human body a sense of coolness. It can react with human chemicals to make the human body feel cool. These finishing agents can contain aromatics and give the human body a sense of freshness at the same time

heat resistant finishing: this kind of finishing agent can make the fabric have heat resistance. Due to the porosity and infrared radiation of the fabric, the fabric has heat insulation

hydrophilic finishing: hydrophilic finishing agent can endow the fabric with good moisture absorption and softness, and the fabric can be treated by rolling drying or impregnation process