CN-121975054-A - Method for producing crosslinked PVC (polyvinyl chloride) by using vinyl chloride monomer

CN121975054ACN 121975054 ACN121975054 ACN 121975054ACN-121975054-A

Abstract

The invention belongs to the technical field of vinyl chloride preparation, and particularly relates to a process method for producing crosslinked PVC (polyvinyl chloride) by using vinyl chloride monomers. The method comprises the steps of taking triallyl isocyanurate as a cross-linking agent, carrying out suspension polymerization reaction on the triallyl isocyanurate, a compound initiator consisting of azodiisobutyronitrile and tert-butyl peroxybenzoate, a compound dispersing agent consisting of methyl cellulose and sodium dodecyl sulfate and a refined vinyl chloride monomer, and carrying out heat treatment on the product under a reduced pressure condition after the reaction is finished to obtain a cross-linked PVC product. According to the invention, through the optimized raw material system and process conditions, the effective regulation and control of the crosslinking process are realized, and the problems of uneven crosslinking, serious degradation and the like in the prior art are solved. The crosslinking degree of the prepared product is 18-32%, the heat resistance and the mechanical property are obviously improved, and the process is stable and suitable for industrial production.

Inventors

LI YAWEN
JIA XIAOJUN
PEI YINGGE
Jing Yuntian
LIU YING
ZHANG GUOLEI

Assignees

金川集团股份有限公司
金川集团信息与自动化工程有限公司

Dates

Publication Date: 20260505
Application Date: 20251222

Claims (12)

1. A method for producing crosslinked PVC from vinyl chloride monomer, comprising the steps of: S1, preparing raw materials, namely providing a vinyl chloride monomer, triallyl isocyanurate serving as a cross-linking agent, a compound initiator consisting of azodiisobutyronitrile and tert-butyl peroxybenzoate, and a compound dispersing agent consisting of methyl cellulose and sodium dodecyl sulfate; S2, a polymerization reaction, namely placing the composite dispersing agent, the vinyl chloride monomer, the cross-linking agent and the compound initiator into a reaction kettle for suspension polymerization reaction; And S3, performing crosslinking post-treatment, namely performing heat treatment on the reaction product after the polymerization reaction is finished, wherein the heat treatment is performed at the temperature of 120-150 ℃ and under the reduced pressure condition of 0.02-0.05 MPa, and the heat treatment time is 2-4 hours, so as to obtain the crosslinked PVC product.
2. The method for producing crosslinked PVC according to claim 1, wherein the vinyl chloride monomer is refined by multistage rectification with a purity of 99.9% or more.
3. The method for producing crosslinked PVC according to claim 1 or 2, wherein the triallyl isocyanurate is used in an amount of 0.5% to 2% by mass of the vinyl chloride monomer.
4. A method for producing cross-linked PVC from vinyl chloride monomer according to any of claims 1 to 3, wherein the mass ratio of azobisisobutyronitrile to t-butyl peroxybenzoate in the compounding initiator is 2:1.
5. The method for producing crosslinked PVC according to any of claims 1 to 4, wherein the amount of the compounding initiator is 0.1% to 0.3% by mass of the vinyl chloride monomer.
6. The method for producing crosslinked PVC according to any one of claims 1 to 5, wherein the mass ratio of methylcellulose to sodium lauryl sulfate in the composite dispersant is 4:1.
7. The method for producing cross-linked PVC using vinyl chloride monomer according to any one of claims 1 to 6, wherein the composite dispersant is used in an amount of 0.2% to 0.4% by mass of the vinyl chloride monomer.
8. The method for producing crosslinked PVC according to any one of claims 1 to 7, wherein the polymerization reaction is carried out at a reaction temperature of 45 to 55 ℃, a reaction pressure of 0.5 to 0.8MPa, and a reaction time of 3 to 5 hours.
9. The method for producing crosslinked PVC according to claim 8, wherein the polymerization is performed in a sealed reaction vessel, the pressure is-0.09 MPa to-0.1 MPa, the pressure is 0.15MPa to 0.25MPa after the air is removed, and the stirring speed is controlled to be 100r/min to 150r/min.
10. The method for producing crosslinked PVC according to any one of claims 1 to 9, wherein in the post-crosslinking treatment step, unreacted vinyl chloride monomer is distilled off under reduced pressure, and then antioxidant 1010 is added to the heat-treated material.
11. A cross-linked PVC product made by the process of any one of claims 1 to 10, wherein the cross-linked PVC product has a degree of cross-linking of 18% to 32% and a vicat softening temperature of 95 ℃ to 115 ℃.
12. The crosslinked PVC product according to claim 11, having a tensile strength of 50MPa or greater.

Description

Method for producing crosslinked PVC (polyvinyl chloride) by using vinyl chloride monomer Technical Field The invention belongs to the technical field of vinyl chloride preparation, and particularly relates to a method for producing crosslinked PVC (polyvinyl chloride) by using a vinyl chloride monomer. Background Polyvinyl chloride (PVC) is an important general plastic, has excellent comprehensive performance and low cost, and is widely applied to various fields such as chemical building materials, wires and cables, packaging films and the like. However, the conventional PVC resin has inherent defects of poor heat resistance, limited mechanical strength, poor dimensional stability, etc., which limits its application in severe environments such as high temperature, high stress, etc. To overcome these disadvantages, modification by crosslinking to introduce chemical crosslinks between PVC molecular chains is considered as an effective way to significantly improve heat resistance, mechanical properties and chemical stability thereof. The method for preparing the crosslinked PVC mainly comprises a radiation crosslinking method, a chemical crosslinking method and a post-crosslinking method. The radiation crosslinking method needs to use high-energy rays, has large equipment investment and high operation requirement, is difficult to accurately control the crosslinking process, and is easy to cause excessive or insufficient local crosslinking to influence the uniformity of the product performance. The crosslinking agents such as peroxide and the like commonly used in the traditional chemical crosslinking method have the problems of poor dispersion uniformity, influence of byproducts on the product purity and potential toxicity. The post-crosslinking method is to crosslink the formed PVC product, and has low efficiency, and the crosslinking effect is greatly influenced by the shape and thickness of the product, so that large-scale continuous production is difficult to realize. The technical problems of uneven distribution of crosslinking points, degradation of PVC and the like, which are caused by the degradation of PVC, are commonly faced in the polymerization and crosslinking processes, and the industrial production of high-performance crosslinked PVC is restricted. At present, most of crosslinking agents of polyvinyl chloride are diene or polyene compounds, for example, patent CN02112435A discloses that crosslinking agents containing diene or polyene structures (such as diallyl phthalate DAP, ethylene glycol dimethacrylate and the like) are added in the suspension polymerization process to prepare PVC special resin with extinction performance. The patent CN108084317A promotes crosslinking polymerization through a novel crosslinking agent A, a crosslinking agent B or a crosslinking agent C of a multifunctional ureido monomer containing two or more ethylene double bonds to construct three-dimensional network gel and improve the mechanical property of PVC resin, but has the limitations that firstly the crosslinking agent is synthesized by relying on a patent technology and does not have universality, secondly the process design is only physical mixing and unfolding around a specific crosslinking agent, and does not relate to how to accurately regulate the formation and distribution of crosslinking points through optimized polymerization dynamics and post-treatment processes, and furthermore, the heat resistance of crosslinked PVC is not disclosed, the technical effect is focused on the mechanical property, and the improvement on the key performance is limited. The crosslinking adopted in the patent CN109575176A is one or more than two of allyl methacrylate, 1, 4-butanediol diacrylate, diallyl phthalate, diallyl maleate, triallyl cyanurate, divinylbenzene, ethylene glycol dimethacrylate, glycerol di (meth) acrylate and polyethylene glycol diacrylate, but the whole process needs to prepare a crosslinking functional monomer solution in advance and divide the crosslinking functional monomer solution into A, B parts, then the A part, a dispersing agent and an initiator are prepared into a crosslinking dispersion liquid, and the crosslinking dispersion liquid is continuously dripped into the mixed liquid of pure water, vinyl chloride monomer, a pH regulator, the crosslinking functional monomer solution B, the dispersing agent and the initiator in the reaction process. Therefore, there is a need to develop a novel preparation method of crosslinked PVC that has a controllable crosslinking process, a uniform crosslinking structure, can effectively inhibit degradation, and is suitable for industrial production. Disclosure of Invention The invention provides a method for producing crosslinked PVC by vinyl chloride monomer, which is characterized by comprising the following steps: S1, preparing raw materials, namely providing a vinyl chloride monomer, triallyl isocyanurate serving as a cross-linking agent, a compound initiato