Special Processing Technology Return to the techdata List

Technical parameters: special processing technology
Gel spinning
Using gel spinning - super stretching technique for preparing high strength, high modulus polyethylene is a novel fiber spinning method in the late 1970s. Dutch company DSM was first patented in 1979, followed by the United States Allied Corporation, Toyobo-DSM company jointly established by Japan and Netherlands, Japan Mitsui companies have achieved industrial production. The chemical fiber research institude of China Textile University study the beginning of the project in 1985, and gradually formed its own technology, prepared high-performance ultrahigh molecular weight polyethylene (UHMW-PE) fibers.
Ultra high molecular weight polyethylene (UHMW-PE) gel spinning process are summarized as follows: dissolving the ultra-high molecular weight polyethylene (UHMW- PE) in a suitable solvent to prepare a semi-dilute solution to extrude through the spinneret hole, then cooled the spinning solution with air or water amain, which was solidified into a cold collagen filaments. In the frozen collagen filaments, all of the solvent is almost included, and therefore the state of UHMWPE polymer chains disentanglement is well kept down, and the temperature was decreased, resulting in ultra-frozen gel molecular weight polyethylene (UHMW-PE) folded chain lamellae formation. Thus, by ultra-heat drawing of frozen collagen filaments times can make macromolecular chains orientate sufficiently and crystallize highly, and thus put the chain folded into a straight-chain macromolecules, thereby producing a high strength, high modulus fibers.
Ultra-high molecular weight polyethylene (UHMW-PE) fiber is the world's third generations of specialty fibers, strength up 30.8cN / dtex, specific strength is the highest in the field of chemical fiber, but also has good abrasion resistance, impact resistance, corrosion resistance, lightfastness and other excellent performance. It can be made ​​directly ropes, cables and nets, and a variety of fabrics: bulletproof vests and clothing, cut resistant gloves, bulletproof effect of body armor which is superior to Kevlar. The international community has ultra-high molecular weight polyethylene (UHMW-PE) fiber woven into rope of different fineness, replacing the traditional steel cables and synthetic fiber rope. Ultra-high molecular weight polyethylene (UHMW-PE) fiber composites have been used in the military's armored shell, protective shell of radar cover, helmet, etc; Sporting Goods has been made ​​on the bowstring, sleigh and skis, etc..
Lubricated extrusion (injection)
Lubricated extrusion (injection) molding formed a lubricating layer between the extrusion (injection) material and the mold wall, thus reduced the shear rate difference of the material points, to reduce the deformation of the product, while it can be improved the high viscosity of the polymer extrusion molding (injection) speed at a low temperature,   low power conditions. The method of producing a lubricating layer is mainly followed: self-lubricating and co-lubrication.
The self-lubricating extruded (injected) of ultra high molecular weight polyethylene (UHMW-PE) is added an appropriate amount of external lubricant to reduce the friction and shear between polymer molecules and the wall of the mold, to improve the uniformity of the material flow , release effect and extrusion quality. External lubricant mainly contain higher fatty acids, composite resin, silicone resin, paraffin and other low molecular weight resin. Prior to extrusion (injection) processing, the lubricant is first mixed with a processing aid, together with other materials, the production, the lubricant spreads from the materials, a lubricant layer is formed to realize self-lubricating extrusion molding (injection).
The patent reports: 70 parts of paraffin oil, 30 parts of ultra-high molecular weight polyethylene (UHMW-PE) and 1 part of Aerosil (finely divided silica) were mixed to granulate, at a temperature of 190 ℃,  can achieve a smooth extrusion (injection).
The co-lubricated extrusion(injection) of ultra-high molecular weight polyethylene (UHMW-PE) has two cases, one is that using the slit method, the lubricant is pressed into the mold and make it form a lubricating layer between the molten material and the inside of mold; Second is mixed with the low viscosity resin, making it as part of the product. Such as: the production of ultra-high molecular weight polyethylene (UHMW-PE) sheet, transporting the SH200 silicone oil into the mold cavity by a metering pump as a lubricant, the resulting product has significantly improved the quality of appearance, in particular due to the small extrusive deformation, increasing the tensile strength.