Application of polymer plasticizer in PVC
1. PVC/polyester plasticizer
Polyester plasticizer is one of the earlier application polymeric plasticizer, mainly composed of binary acid and dibasic alcohol made by condensation reaction, species have atopic acid benzene anhydride polyester and polyester, etc., molecular weight is controlled in 3000, it is not only resistant to pull out, it is not easy migration, small molecules and can reduce the soft PVC plasticizer migration. Polyester plasticizer improves the processing performance of PVC, and is suitable for plastics such as leather, toys, medicine and food, which are resistant to oil, water and solvent. When applied in soft PVC, it can be added up to 70%.
The effect of polymer plasticizer on plasticizer was influenced by relative molecular mass and branching. With the improvement of the relative molecular weight of the polyester plasticizer, the glass transition temperature of soft PVC was reduced; the plasticizing effect and heat resistance and solvent resistance were improved. The increase of the branched degree of polyester plasticizer improves the heat resistance of soft PVC.
In PVC/polyester plastic sol system, the appropriate amount of polyester (polyethylene glycol ester, PPA) is 50~70 (quality part). In this condition, the thermal stability of the plastic sol is better. At present in large Numbers in the coating process of car production by adopting the technology of "wet touch wet", in order to avoid plasticizer by organic solvent extraction, choose PVC/polyester plastisol traditional small molecule plasticizer system, can achieve good effect. As a plasticizer additive, the sealing end polyurethane can improve the shear strength of PVC/DOP/packing plastic sol.
2. PVC/LNBR
Liquid is butadiene nitrile rubber and a small amount of acrylonitrile copolymer, by way of free radical emulsion polymerization synthesis, molecular weight smaller (below the relative molecular mass is in commonly 5000), room temperature with liquidity. The earliest to functional groups and a variety of random functional groups, then to end functional groups class is given priority to, as hydroxyl-terminated liquid NBR (HTBN), terminal carboxyl liquid butadiene-acrylonitrile rubber (CTBN), sulfhydryl liquid NBR (MTBN) and end amine liquid NBR (ATBN) and so on. The end functional groups containing rubber during solidification, molecules participate in end functional groups of cross-linking, made of vulcanized rubber crosslinking network does not contain free chain end, junction between relative molecular mass is bigger than ordinary rubber, structure neat, no short chain, so the softness is very good, homebred brand is mainly Lanzhou petrochemical liquid CTBN - 26, liquid nitrile - 40 and carboxyl nitrile, combined with the mass fraction of acrylonitrile were 23% ~ 27%, 30% ~ 40% and 30% ~ 35%.
Will LNBR replace phthalic acid type of small molecule plasticizers in PVC paste resin, solvent resistance, oil resistance can be obtained from good plasticization of PVC material, the material is not only high strength, small deformation, and the extraction rate of n-heptane is extremely low, can be used in contact with the food industry.
Liquid butyronitrile rubber is used to make up the defect of solid butyronitrile rubber which is not easily mixed with PVC resin. Therefore, it can be used to modify PVC foamed plastics. The LNBR of 0~8 (quality part) makes the tensile strength, elongation and hardness of PVC foam plastics increase greatly, but the foaming ratio decreases.
LNBR can improve the elasticity of PVC while replacing ordinary plasticizer such as DOP, DBP, etc. Will join the PVC/DINP LNBR (100/80) in a mixture made of thin film and test the mechanical properties, when adding amount to 20 LNBR elongations at break than not when adding increased one times, while the tensile strength did not.
