Optical-grade polymethylmethacrylate continuous solution polymerization process and equipment thereof

Abstract

The invention relates to the preparation method of a polymer compound and a plant used therefor, in particular to a continuous solution polymerization process of optical-grade poly(methyl methacrylate) and the plant used therefor. The plant used for the continuous solution polymerization process of optical-grade poly(methyl methacrylate) comprises a refining and distillation device, a polymerization reaction device, a two-stage devolatilization device, and a wire-drawing and granulation device connected with each other in series, and specifically comprises a feed refining tower, a polymerization reaction groove, a recovering and refining tower, heaters a and b, and devolatilization tanks a and b. The continuous solution polymerization process can prepare optical-grade poly(methyl methacrylate) from monomers, a copolymer, a stabilizing agent, a molecular weight regulator, an initiator and a solvent according to the following four steps: (1) refining and distillation, (2) polymerization reaction, (3) flash devotilization and (4) wire drawing and granulation. The PMAA produced by the process has the advantages of high safety, no gel accumulation, improved physical properties and color of the produt, low energy consumption, environmental protection, clean production, good weathering resistance of the product, anhydrous polymerization, no black spots on the product, etc.

Description

technical field [0001] The invention relates to a preparation method of a polymer compound and equipment used, in particular to an optical-grade polymethyl methacrylate continuous solution polymerization process and equipment used. Background technique [0002] Polymethyl methacrylate, English name Polymethyl Methacrylate, referred to as PMMA, is a rigid and transparent thermoplastic material with a wide range of applications. Its polymerization preparation methods include suspension method, emulsification method, bulk method and solution method. Among them, the emulsification method The finished product has poor transparency and is expensive, so it is not suitable for commercial production. The preparation process of suspension method is: add initiator to MMA and copolymer, polymerize to a certain conversion rate, then add a large amount of water and suspending agent to further polymerize, PMMA forms beads suspended in water, dehydrated, washed, dried and then extruded mac...

AI Technical Summary

Problems solved by technology

Bulk polymerization monomer concentration is high, it is easy to produce gel, and the reaction rate is fast, and the exothermic reaction is not easy to control in large-scale production

In the 1980s, the U.S. PTI company proposed that the solution polymerization method improved the aforementioned problems, and U.S. Patent No. 4,728,701 disclosed a method for acrylic ester polymerization on March 1, 1988; U.S. Patent No. 4,933,400 disclosed on June 12, 1990 A continuous solution polymerization method for methacrylate, but these polymerization methods use a solvent ratio as high as 60% of the feed, the reaction rate is too slow, and the volume of the reactor is significantly increased, resulting in high investment. At the same time, the process still has problems The following disadvantages: 1. The polymerization reaction temperature is lower than 100°C, and the dosage of the initiator and the molecular regulator is relatively increased, which affects the purity and recovery and refining problems

2. Two-stage polymerization tank is used, because the copolymerization speed ratio of MMA and its copolymers such as MA or EA is different, resulting in the difference in the copolymerization ratio of the first-stage reaction and the second-stage reaction of the polymer.

3. The devolatilization process is poor. When the solid content in the polymerization process reaches more than 40%, the polymerization solution is transported to the shell-and-tube heater for preheating through the gear pump. The process is from bottom to top. The polymerization solution passes through the heating tube of the heater, and At the end, the outlet pressure is controlled by a control valve to maintain the liquid state in the pipe. This method has a low heat transfer coefficient and poor heating effect, resulting in a bulky heater. The polymerization solution stays in it for a long time, and it is easy to produce oligomers and oligomers. Serious affect quality

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