Method for preparing high-rigidity chlorinated polyethylene

Abstract

The invention discloses a method for preparing high-rigidity chlorinated polyethylene by using a hydrochloric acid phase process, which comprises the following steps: adding high-density polyethylene, dispersing agent and anti-adhesion agent in hydrochloric acid solution in a stirring state to prepare suspension; feeding in chlorine into the suspension in two stages for implementing chlorination reaction, with the reaction temperature being from 30 to 140 DEG C, the reaction time being from 3-5 hours and the feed-in amount of the chlorine being 0.5-1.2 times as large as the weight of the high-density polyethylene; afterwards, separating, washing, dehydrating and drying the chlorinated products to result in the high-rigidity chlorinated polyethylene product with 20-35wt% of the chlorine content, DSC which is not more than 5J/g, 60-80 of Shore hardness and more than 2.0MPa of 100% modulus at definite elongation. The high-rigidity chlorinated polyethylene prepared according to the method can take the place of high-price MBS to serve as an anti-impact modifier of hard PVC articles and meet the demands of materials about rigidness and toughness.

Description

technical field [0001] The invention relates to the technical field of polymer materials, in particular to a method for producing high-rigidity chlorinated polyethylene by a hydrochloric acid phase method. Background technique [0002] Polyvinyl chloride (PVC) is one of the most widely used general-purpose plastics and occupies a very important position in material engineering. It has excellent mechanical properties and is widely used. However, PVC is a hard and brittle material with low impact strength and poor low-temperature toughness. Therefore, during the processing of PVC, it is necessary to add impact modifiers to improve product toughness and expand product applications. In recent years, in rigid PVC products such as PVC pipes and profiles, commonly used modifiers include chlorinated polyethylene (CPE), acrylonitrile-butadiene-styrene copolymer (ABS), methyl acrylate-butanediene ethylene-styrene terpolymer (MBS), ethylene-ethyl acetate copolymer (EVA), acrylic copol...

AI Technical Summary

Problems solved by technology

Chlorinated polyethylene is used for profile modification and is widely used, but it is used in the field of rigid pipes and is rarely used in urban water supply and drainage

The reason is that chlorinated polyethylene is obtained by chlorination of high-density polyethylene. The product obtained after chlorination has a flexible molecular segment, which can better improve the toughness of rigid plastics such as PVC, but low modulus and low hardness will Reduce the rigidity of the product, resulting in a decrease in the ring rigidity and compressive strength of the pipe product, and the use is limited

[0004] In order to ensure the rigidity of the pipe, in the current processing process, the terpolymer (MBS) of methyl acrylate, butadiene and styrene is mostly used as the impact modifier, but adding MBS as the impact modifier in The following problems exist in actual production: first, the processing torque of MBS is high, and the energy consumption in the production process increases; second, the price of MBS is high, the production cost of manufacturing enterprises increases, and the competitiveness of products decreases; Products are used, so the use of MBS in pipes is subject to certain limitations