processing aids in different processing methods and the application features

Processing aids action principle: PVC melt poor scalability, easily lead to melt broken; PVC melt relaxation is slow, easily lead to the product surface rough, dull and shark skin and  antimony oxide so on. Therefore, PVC processing often necessary to add processing aids to improve the melt of the above-mentioned drawbacks. Processing aids as a class can improve the performance of resin processing aids, which consists of three main modes of action: promoting resin melt, the melt rheology modifiers and gives lubrication. 1 PVC resin promoting resin is melted when heated under shear force, processing modifier first melted and adhered to the surface of the PVC resin particles, based on their compatibility with the resin and the molecular weight, the viscosity of PVC and friction increases, thereby effectively the shear stress and heat transfer to the PVC resin, PVC accelerate melting. (2) has a melt rheology modified PVC melt strength is poor, poor scalability and melt fracture and other shortcomings, while processing modifier can improve the melt above problems. Its mechanism of action is: to increase the  azodicarbonamide melt viscoelasticity of PVC, thereby improving the die swell and increased melt strength. 3 gives lubricity compatibility with PVC processing modifier part first melting molten play a catalytic role; partly incompatible with PVC molten resin to migrate outside the system, thereby improving mold release. ACR processing aids commonly used species category, ACR is methyl methacrylate. ACR domestic products ACR-201, ACR-401 and other varieties. ACR-201 methyl methacrylate and acrylate graft copolymer, the appearance of a white powder, the PVC can be added to improve the melt strength and melt elongation. ACR-201 is mainly used for rigid PVC profiles, pipes, bottles and sheets, the amount of 0.5 to 2 parts. ACR-401, methyl methacrylate, ethyl acrylate, butyl acrylate and styrene monomer from four kinds, are core - shell copolymers, AMS class, AMS-based oligomeric α-methyl styrene material, which is also called hexamer M-80, it is non-toxic and transparency, and can improve the processability of PVC resistance and organic pigments  luster of products. AMS for rigid PVC, the hard tube add 2 to 5 parts, 3 parts of a transparent film, was added 10 parts of the floor. Copolymers of butadiene and acrylonitrile P83, the surface treatment by the PVC latex, can be used as processing aids, added in an amount up to about 20 parts. 820-G is a chlorinated paraffin and polypropylene oxide - ethylene made by free radical grafting, which can improve the processability of PVC, gloss and feel, added in an amount up to 5 to 10 parts.