Synthetic method of PVC modifier

Abstract

The invention belongs to the PVC modification field, and more specifically relates to a synthetic method of a PVC modifier, the PVC modifier is characterized in that butylbenzene latex with high content of butadiene is synthesized, wherein butadiene accounts for 75-95% of total amount of butadiene, then the butylbenzene latex is taken as seed for polymerization to obtain a SBR emulsion with suitable particle size, styrene and methyl methacrylate are grafted to the butylbenzene latex by two steps, the total formula amount of styrene and a few of methyl methacrylate are added in a first step, residual methyl methacrylate is added in a second step, an anti-oxidant is added finally, then dilute sulphuric acid or dilute hydrochloric acid is performed agglomeration, and the processes of washing and drying are carried out to obtain the product. Compared with a MBS mark, the low temperature impact performance of a MBS / PVC mixture can be enhanced by more than 50% on an original base, haze is obviously reduced, the color of a sheet material is pure, and the prepared product is obviously better than the MBS resin prepared by the other technologies.

Description

technical field [0001] The invention belongs to the field of PVC modification, and in particular relates to a synthesis method of a PVC modifier. Background technique [0002] The terpolymer of butadiene, styrene and methyl methacrylate is referred to as MBS resin for short. Generally, the preparation of low-temperature transparent impact-resistant MBS is mostly carried out by the process of expanding the diameter of latex. The following patents are reported: EP0 , 144,081 discloses the use of carboxyl-containing styrene-methyl methacrylate-methacrylic acid copolymer latex to expand the usually synthesized small particle size styrene-butadiene latex to obtain a large particle size latex with a particle size above 200nm , and then grafted to obtain MBS resin with high impact resistance. J56167704 uses organic acids, such as lactic acid, as a diameter expander. EP62901 also mentions that the styrene-butadiene latex is agglomerated and then grafted by polymer diameter expansi...

AI Technical Summary

Problems solved by technology

The disadvantage of the above patents is that the latex particle size is too large due to agglomeration, which affects the transparency of the product. At the same time, the agglomeration itself is also a process of changing from the steady state of the latex to the unsteady state, which is likely to cause a decrease in the stability of the latex and affect the polymerization. stability

There are three deficiencies in the above-mentioned process: the one is that the synthetic high butadiene content styrene-butadiene latex particle size is too large, which affects the transparency of MBS; the second is that the grafting monomer is methyl methacrylate in the grafting process, and It is one-step polymerization, not grafting according to the same or similar refractive index; the third is to add a heat-resistant modifier in the post-treatment process, which will cause odor and discoloration during the MBS / PVC processing process, affecting the color of the product

The deficiencies of this process are reflected in: one is that the preparation process of styrene-butadiene latex is not mentioned; two its graft monomer adopts styrene and acrylonitrile, and the impact resistance of the prepared MBS resin is better, but transparent The performance is not good, because the principle of the same or similar refractive index is not considered in the particle design process

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