Expandable foaming microspheres with excellent solvent resistance and preparation method thereof

Abstract

The invention discloses an expandable foaming microsphere with excellent solvent resistance and a preparation method thereof. The expandable foaming microsphere comprises a thermoplastic resin shell and a foaming agent, wherein the thermoplastic resin shell contains carboxyl and a polycarbodiimide cross-linking agent, and the foaming agent is encapsulated in the shell and the boiling point of thefoaming agent is not higher than the softening point of thermoplastic resin. The expandable foaming microsphere has excellent solvent resistance, and the preparation method is simple, low in toxicityand environment-friendly.

Description

technical field [0001] The present invention relates to heat-expandable microspheres, more specifically, to an expandable foamed microsphere with excellent solvent resistance and a preparation method thereof. Background technique [0002] Thermally expandable microspheres are polymer particles with a core-shell structure that expands when heated. The microspheres contain a permeable low-boiling hydrocarbon, while the outer shell consists of a gas-tight thermoplastic polymer that controls the release of hydrocarbons. At room temperature, the polymer shell is rigid. Nevertheless, the shell softens when heated, while the hydrocarbons increase the internal pressure. Eventually the microsphere swells like a balloon and increases significantly in volume. Once the microspheres are cooled, the polymer shell remains rigid and expands, so the volume remains the same as when heated. This reduces the density of the microspheres from about 1100 kg·m-3 to about 30 kg·m-3. However, co...

AI Technical Summary

Problems solved by technology

However, the titanium salt used in this technology is expensive, and titanium metal has a catalytic effect on many polymers, causing degradation and other problems, which is not conducive to the promotion of this type of expandable foamed microspheres.

[0009] Chinese Patent Publication No. CN 109705392A reports a kind of expandable microsphere with excellent solvent resistance and its preparation method. The preparation method utilizes a silane coupling agent, Epoxy silane coupling agent, titanate coupling agent or water-soluble aziridine crosslinking agent, but silane coupling agent, epoxy silane coupling agent, titanate coupling agent these are organic / inorganic hybrid Small molecule cross-linking agent, after cross-linking, it forms an organic / inorganic hybrid shell. This shell has good solvent resistance but insufficient elasticity, and the foaming ratio is slightly reduced. The aziridine used in it is organic, although its cross-linking The expansion ratio of foam microspheres will not be significantly reduced, but aziridine is highly carcinogenic and is not conducive to large-scale use; Yellow viscous liquid, because the nitrogen-containing group itself is oxidized in the air and easily turns yellow, resulting in the production of room temperature crosslinking agent products from colorless, transparent or slightly yellow to yellow, resulting in many users unable to use because the color is too dark , especially in the ink and coating industry

[0010] In recent years, polycarbodiimide cross-linking agent, as a new type of environmentally friendly water-based coating cross-linking agent, has the characteristics of low toxicity and non-yellowing of cross-linked products. However, There is no literature report that it can be used for expandable foamed microspheres

Images