Exactly. I work in a silk factory.
Production technology of silk
There are many production methods of silk fabrics, but they basically include five production processes: raw material preparation, web formation, fiber web reinforcement, finishing and winding.
Raw material preparation includes fiber opening, mixing, impurity removal, oil agent and antistatic agent. It is a necessary preparation process to ensure the quality of fiber web.
Web-forming is the process stage of forming fiber web and one of the important processing procedures in silk production. The quality of fabrics directly affects the properties and uses of silk fabrics. There are three main methods to form silk fabrics: dry method, wet method and polymer extrusion method.
Web reinforcement is an important process to make the web have a certain strength and form a real silk fabric structure, which plays a decisive role in product quality. At present, the commonly used reinforcement methods are mechanical reinforcement, chemical reinforcement and thermal bonding reinforcement.
The finishing process includes drying, baking, finishing, calendering, embossing, coating, stacking, dyeing, printing and cutting. Its purpose is to improve the use performance of the final product and increase the appearance.
Finally, roll the silk cloth as required.
I. Overview of Dry Silk Fabric Production
Dry production is the earliest method used for silk fabrics, and it still dominates the production of silk fabrics at present.
1. Preparation of fiber web production The preparation process of dry web formation includes mixing, cleaning and adding necessary oil. The mixed washing machines used in the production of silk fabrics are mostly traditional cotton spinning or wool spinning equipment in China, while there are some short-process special equipment for the production of silk fabrics abroad.
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1) mechanical (carding) web-forming: it is to process the fibers after the preparation process into a thin web composed of a single fiber, which is used for stacking or directly strengthening the web. The carding of fibers is mainly done on the carding machine. Carding machines include single cylinder type, roller cylinder type and flat cylinder type. After carding, the thin web with unidirectional fibers can be reinforced directly, or it can be reinforced after being laid into a web by a certain method. Stacking can be combined in parallel, cross and other ways, but the fibers in the net are all arranged in one direction, so the longitudinal and transverse strength of the finished product is very different. In order to reduce this difference, the fibers in the net can be arranged in a certain degree of disorder through special methods.
2) Air-laid: Air-laid is to transport fibers by air to form a uniform fiber web with disordered fibers. The fibers in the net are distributed in three directions, and there is little difference in longitudinal and transverse strength. The process is as follows: after opening, removing impurities and mixing, the fibers are fed into a high-speed rotating cylinder and further combed into single fibers. Then, under the combined action of the centrifugal force of the cylinder and the airflow, the fiber falls off from the sawtooth, is evenly transported by the airflow, and condenses on the screen to form a fiber web.
3. Fiber web reinforcement
1) mechanical reinforcement
A) acupuncture strengthening. Needle punching is the main reinforcement method for dry silk fabrics. It uses external force to wind fibers into felt-like fabrics through the barbs of needles. The feeding curtain of the needling machine sends the fluffy fiber web to the bed board, and the needle board with needles moves up and down, so that the barbed needles can needle up and down on the fiber web. Some fibers are brought into the net or the bottom of the net from the green surface of the net through the barbed movement of needles, so that the fibers are inserted up and down and play a reinforcing role. The needled fiber web is output by another pair of output rollers. In order to improve the surface quality of products, fiber webs can be needled in both directions besides unidirectional needling. In addition, fancy needling can be carried out to make the surface of the product have a specific fancy effect. In the process of acupuncture, acupuncture depth, acupuncture density, needle type and needle arrangement are the main factors affecting product quality. Needle punching is mainly suitable for producing medium-thick silk fabrics.
B) joint edge reinforcement. The sewing method is to reinforce the net, yarn layer or nonwoven material layer (such as foam plastic, film, etc.). ) Through the action of the looping mechanism, the yarn (or the fiber bundle hooked in the net) is stitched to make it a stitched silk. In addition, it can also be woven into the base fabric (woven fabric or stitched silk fabric) to produce a loop effect and become a loop-type silk fabric. Sewing methods can be divided into three types: net-stitched yarn type, yarn-free net type, terry type and yarn-stitched type. Sewn silk fabric is similar to traditional textiles in appearance and feel, and is suitable for clothing, household and industry.
C) spray net method. Jet-jet weaving, also known as hydraulic needling, is a silk weaving technology that developed late. It uses high-pressure fine water jet to act on the web of metal screen (vertical jet), so that the fibers move downward under the action of interstitial hydraulic pressure, thus realizing entanglement between fibers (similar to acupuncture) and strengthening the web. The silk fabrics processed by spray netting have the characteristics of soft hand feeling, fluffy, high hygroscopicity and basically no fiber scraps, which are mainly used in sanitary materials, followed by industrial and civil products.
2) Chemical bonding reinforcement: Chemical bonding reinforcement is a network reinforcement method with the longest application history and the widest application in the production of silk fabrics, but the proportion of this method is gradually decreasing in recent years. Chemical bonding method is to use a variety of methods to evenly distribute the adhesive in the net in the form of emulsion or solution, and after curing, make the fibers in the net adhere to each other to strengthen the net. Chemical bonding methods can be divided into immersion bonding, foam immersion bonding, spray bonding, printing bonding and solvent bonding.
Impregnation bonding method is to saturate the fiber web after it passes through an adhesive tank, then squeeze out the excess adhesive with a pair of rollers, and then dry and bake to form saturated impregnated silk cloth. Because the silk produced by this method has a hard hand feel, it is only suitable for lining some clothes.
Foam impregnation is a method of impregnating and bonding silk fabrics with foam adhesive. This method is one of the important methods to produce thin and medium-thick silk fabrics.
Spray bonding method is to spray the adhesive on the fiber web with compressed air through a spray gun. It is mainly suitable for producing silk fabrics with high bulkiness and porosity. Such as glue-sprayed cotton, filter materials, etc.
3) Thermal bonding enhancement: Thermal bonding enhancement is to heat the web where the main fibers are mixed with hot-melt fibers, hot-melt powder or hot-melt films, so that the hot-melt materials in the web are melted, and the joints between the fibers are melted and bonded, and then cooled and fixed, so that the web is enhanced into cloth. It includes hot melt bonding method and hot rolling bonding method.
The hot melt bonding process is simple, which mainly uses the drying room to heat and reinforce the fiber web, or it can be heated and then pressed by rollers.
Hot-rolling bonding method is to heat and pressurize the mesh mixed with hot-melt fibers by using a uniformly heated roller, so that the hot-melt fibers in the rolling area are fused and welded with the main fibers at the joints, which plays the role of reinforcing cloth. This method can also be used to enhance the auxiliary bonding and calendering of silk fabrics.
In addition, thermal bonding can also be used as an auxiliary reinforcement after mechanical reinforcement. At present, this law is in the ascendant.
Two. Summary of silk fabric production by polymer extrusion
1. Overview of producing silk fabrics by textured fiber web method; Spinning fiber web method is the most important and widely used polymer extrusion method. In China, the output of silk products produced by this method has accounted for about 30% of the total output of silk products in China.
Spinning-netting method is based on the principle of chemical fiber spinning. In the process of polymer spinning, fibers are used to form a net, and then the net is bonded by itself or formed into silk cloth through mechanical, chemical and thermal strengthening. Melt spinning technology is used for spinning and netting, including three key processes: spinning, stretching and netting. Due to the characteristics of short process flow and high product strength and elongation, this spinning method has a good development prospect.
2. Overview of silk cloth production by melt blowing: First, the polymer is melted into a melt, sent to an extrusion cavity, and extruded through a row of flat spinnerets. High-speed hot air flow is introduced from the pipeline and ejected at high speed from the flat slits on the upper and lower sides of spinning cotton. It disperses and breaks the unformed melt trickle to form very fine irregular superfine short fibers, and then condenses on a porous roller or curtain net to form a fiber web, and finally the fiber web becomes a silk fabric through self-bonding or thermal bonding.
Melt-blown silk fabrics are mainly used as high-efficiency air filtration materials, oil-absorbing felt, medical and health care products, etc. This is a very developed silk fabric.
Three. Summary of wet silk fabric production
Wet process is one of the fastest methods to produce silk fabrics. It suspends the fiber in water and then transports the slurry to the filter screen. Because the water will run away, the fibers will be evenly distributed on the filter screen to form a net. Finally, through bonding, toughening and drying, it becomes silk fabric.
The production process of wet method is basically similar to that of dry method, including four stages: fiber preparation, wet networking, bonding reinforcement and post-treatment.
1. fiber preparation this process is to open the fiber raw materials placed in the hydrolysate into single fibers, and at the same time, fully mix different fiber raw materials to make fiber suspension slurry, and then transport the suspension slurry to the web-forming mechanism without fiber agglomeration.
2. Wet-laid fiber is distributed on the screen in wet state. Wet wire, inclined wire and rotating wire. The main difference is the shape of the net curtain. Inclined screen method is inclined flat screen, and circular screen method is circular screen.
3. Bonding and strengthening wet dust net is similar to dry method, and it can be strengthened by gluing or hot rolling.
4. Post-treatment The post-treatment of wet silk fabric includes drying and baking, which is similar to dry bonding.
Four. Overview of silk fabric finishing
The post-finishing of silk fabrics is mainly to improve the service performance of silk fabrics, improve the appearance and increase the variety of products, mainly including dry finishing and wet finishing.
Shrinkage finishing in dry finishing is to increase the compactness and strength of products. Soft finishing makes the product plump and feel good. Calendering and embossing finishing can keep the product uniform in thickness and produce concave-convex patterns on the surface of silk fabrics. In addition, dry finishing also includes coating finishing, mechanical opening and slit finishing.
Wet finishing of silk fabrics includes washing, bleaching, dyeing, printing, water repellent finishing, water absorption finishing, dust absorption finishing, flame retardant finishing, antistatic finishing and sanitary finishing.
However, not all silk fabrics need finishing, which depends on the use of the final product.