Product development of casein fiber
Casein fiber is a high-protein fiber made by bionics based on the spinning principle of natural protein fiber of silk. This article discusses the key technologies of yarn production and the basic characteristics of fabrics by analyzing and studying the properties of casein fiber.
1 Foreword
Casein fiber, commonly known as milk protein fiber, is a type of regenerated protein fiber. It is made by dewatering, skimming and kneading liquid milk into casein slurry, which is then wet-spun through a new process and It is processed by high-tech means. It was first produced by Japan’s Toyobo Company through the graft copolymerization of protein and acrylonitrile. The trade name is “Chinon”. “Chinon” has the look and feel of silk and is particularly known for its good moisture conductivity and quick-drying properties, making the fabric woven into a comfortable and lightweight fabric.
my country’s rich milk cheese resources, coupled with the automation of machinery and equipment, and the improvement of materials, provide favorable conditions for the development of milk fiber. In recent years, many units across the country have conducted research on short fibers and filaments of various process routes and achieved some results. China Textile University and Shanghai Sangun Group Co., Ltd. cooperated to develop casein fiber and completed qualified laboratory research; Jiangsu Hongdou Industrial Co., Ltd. successfully developed casein silk T-shirts; Shanghai Zhengjia Milk Silk Clothing Co., Ltd. independently developed and developed The “Zhengjia” casein fiber has been determined to be pure milk silk by the Shanghai Entry Inspection and Quarantine Bureau, and the research and development of milk silk fabrics has also been successful.
2 Raw material characteristics of casein fiber
Casein fiber is the third generation of new fiber after natural fiber and second generation synthetic fiber. Its strength is higher than cotton and silk, close to polyester, especially after absorbing moisture, it still maintains a high strength, and its wet strength is much higher than that of silk; its mildew-proof and moth-proof properties are better than wool; it has natural antibacterial properties Function. The protein contained in milk is in harmony with human skin. Clothing made of casein fiber is not only smooth as milk, but also light, soft and breathable. It has a silky feel, soft and elegant luster, and has excellent thermal insulation, moisture conductivity and quick-drying properties. It has the same silky feel as silk, integrating beauty, comfort and convenience. Table 1 lists the physical indicators of casein fiber and common fibers.
Comparing the strength and elongation of casein fiber with commonly used fibers, its strength is only lower than polyester, comparable to silk and acrylic fiber, and its initial modulus is comparable to cotton and silk, and higher than acrylic fiber, which is enough to provide yarn strength; fiber The elongation is small, the dimensional stability of the yarn and fabric is good, and the moisture regain is high.
The nature of casein fiber determines its difficulty in spinning, but as long as the process is properly designed and continuously improved in practice, its spinnability can be improved.
Shanghai Shiqi Cotton’s spinning experimental center has developed various yarn products based on fiber characteristics. (1) 14.5rex (40Ne) blended yarn: 10% casein fiber, 20% sheep wool, 30% Lyocell, 40% JC; (2) 18.3tex (32Ne) 100% casein fiber yarn.
The fiber used is 8.3tex (70Ne) cotton top; 1.5D×38mm Loycell fiber; cotton grade 133. Strip mixing is carried out in the drawing process.
The performance indicators of casein fiber are: length 51 mm, fineness 1.365 dtex, breaking strength 3.15 g/dtex, specific resistance 2.35×109Ω·g/cm2, oil content 0.12%, moisture regain The rate is 5.0%, and the curl rate is 8%-10%.
3 Configuration of each spinning process
This experimental spinning process configuration adopts the blowing and carding processing process.
3.1 Carding process
Based on the properties of casein fiber, measures such as increasing oil content and reducing static electricity are adopted. Spray 30% concentration of electrostatic agent and let it sit for 32 hours. After sampling inspection, the physical indicators of the fiber have been greatly improved, which reduces the static electricity of the fiber and has a certain humidity, which brings favorable conditions for the production of subsequent processes. The process is doffer 20 r/min, cylinder 300 r/min, licker-in 800 r/min, cover plate 80 mm/win, and the basis weight of the produced sliver is 19.5g/5m.
3.2 Pre-drawing process
The casein fiber slivers are pre-drawn before mixing, fed with 8 slivers, and the drafting multiple is 8.12 to increase the flatness of the fiber and reduce the quality. Unevenness, reducing the quality difference between combed sliver and combed sliver, improving the quality of the card sliver, and the obtained pre-drawing sliver has a quantitative value of 17.38 g/5m.
3.3 Mixed drawing process
The first feed adopts 7 rods, 3 rods of combed cotton (14.78g/5m), 4 rods of casein fiber pre-drawing (17.38g/5m), The roller spacing (front × rear) is 12mm × 15mm, the roller pressure (front × middle × rear) is 400kN × 600kN × 440kN, the design draft multiple is 7.96, the front roller speed is 1 400 r/min, and the sliver delivery quantity is 15.58g/5m; both the second and third unions use 8 rods for feeding, the designed drafting multiple is 8.2, and the sliver delivery quantity is 15g/5m.
3.4 Roving process
Due to the poor cohesion of casein fibers, the rollers are more pressurized, so a small-diameter cotton collector should be used to appropriately increase the roving twist coefficient. The design draft multiple is 9.57; the roving twist configuration is 5.31 twist/10cm; the front roller speed is 180 r/min; the spindle speed is 700 f/min; the roving basis weight is 3.2 g/10m.
3.5 Spinning technology
When selecting the number of travellers, it should be lower than that of conventional yarn, and the speed should also be reduced, which can reduce yarn breakage. Before spinning casein fiber, the drafting channel on the machine must be thoroughly cleaned with alcohol, which can effectively control winding rollers, top rollers and other phenomena to reduce end breakage. The drafting multiple in the back area should be appropriate to reduce the coarse details of the yarn and ensure the quality of the yarn. Double apron weighting arms are used for pressurization. The rollers are pressurized more heavily. The drafting multiple is 47.24, the twist is 86 twists/10em, and the spinning rate is 14 .5tex (40Ne) multi-component blended yarn.
The spinning process of casein fiber pure spinning yarn can refer to the above process, appropriately increase the twist and reduce the draft multiple, so as to complete the production of pure casein fiber yarn.
4 Yarn performance testing and analysis
4.1 Strong elongation performance
Experimental conditions: room temperature 20°C; relative humidity 65%. Experimental instrument: XL-1 yarn tensile tester; test conditions: gauge 500 mm, stretching speed 500mm/min.
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