Thermally-expandable polymer microsphere special for polyvinyl chloride resin foaming and preparation method thereof

Abstract

The invention relates to a thermally-expandable polymer microsphere for polyvinyl chloride resin foaming and a preparation method thereof, and belongs to the field of expandable particles. The thermally-expandable polymer microsphere consists of a thermoplastic resin shell and a foaming agent encapsulated in the shell; an oil phase composition composed of a polymerizable monomer and a crosslinkingagent is dispersed in an aqueous phase dispersion composition; and in the presence of the foaming agent, the foaming agent is coated in situ through a suspension polymerization reaction to directly prepare the polymer microsphere coated with the foaming agent. The thermally-expandable polymer microsphere is characterized in that the oil phase composition comprises a silane coupling agent in addition to the polymerizable monomer and the crosslinking agent, and the foaming agent is a mixture of isopentane, isooctane and n-octane. The invention provides a thermally-expandable polymer microspherewhich has the advantages of complete core-shell structure, uniform particle size distribution, high foaming agent coating efficiency, good heat resistance of a shell polymer, high initial temperatureduring expansion, high maximum expansion temperature, high foaming ratio, and wide foam stabilizing temperature range, and is special for foaming polyvinyl chloride resin.

Description

technical field [0001] The invention relates to a heat-expandable polymer microsphere specially used for polyvinyl chloride resin foaming and a preparation method thereof. Belongs to expandable particles. Background technique [0002] Thermally expandable polymer microspheres are a multifunctional foaming material with a wide range of uses. It is an extremely small spherical particle with a shell-core structure. The core of the microsphere is liquid low-boiling alkanes, and the shell of the microsphere is a thermoplastic polymer with good airtightness that can prevent the substances in the core from escaping. At room temperature, the shell of the microsphere is hard and the particles are tiny. When heated, when the heating temperature is higher than the glass transition temperature of the shell, the shell material softens and the core material gasifies to generate internal pressure, causing the microspheres to expand. The volume increased significantly. The particle siz...

AI Technical Summary

Problems solved by technology

[0010] However, in the prior art, the heat-expandable polymer microspheres prepared by the suspension polymerization method also have the following deficiencies, and it is difficult to prepare heat-expandable polymer microspheres suitable for polyvinyl chloride resin foaming processing:

[0011] 1. Uneven particle size distribution

[0012] 2. The thermoplastic resin shell polymer of heat-expandable polymer microspheres has poor heat resistance, which leads to yellowing and rupture of heat-expandable microspheres during resin foaming processing

[0013] 3. Core-incomplete structure, low foaming agent coverage

[0014] 5. The heat resistance of the product is not good enough

[0015] 6. The expansion ratio is low, and the temperature range of foam stabilization is not wide enough

[0016] 7. The suspension polymerization reaction time in the prior art is as long as 20 hours, resulting in uneven particle size distribution of the product and low foaming agent coating rate

and increased production costs

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