CN-121991399-A - High-temperature thermal expansion microsphere

Abstract

The invention provides a high-temperature thermal expansion microsphere, which comprises an olefinically unsaturated monomer, a foaming agent, a cross-linking agent, an initiator, a dispersion stabilizer, a dispersion stabilizing auxiliary agent and a dispersion medium, wherein the olefinically unsaturated monomer comprises, by weight, 40-70% of an acrylonitrile monomer, 10-30% of an acrylic monomer, 10-30% of an acrylamide monomer, 0-30% of an acrylic monomer and 5-30% of a silicon-containing acrylic monomer. The invention can obviously improve the foam breaking temperature, durability and foam stabilizing performance of the microsphere.

Inventors

• SHEN JIEFENG
• HUANG TAO
• JI QIAN
• XU PENGJU
• Wei Ruohan

Assignees

• 东华大学

Dates

Publication Date

20260508

Application Date

20241104

Claims (4)

1. 1. The high-temperature heat expansion microsphere is characterized by comprising an ethylenically unsaturated monomer, a foaming agent, a crosslinking agent, an initiator, a dispersion stabilizer, a dispersion stabilizing auxiliary agent and a dispersion medium, wherein: The ethylenically unsaturated monomer comprises, by weight, 40-70% of acrylonitrile monomer, 10-30% of acrylic monomer, 10-30% of acrylamide monomer, 0-30% of acrylic monomer and 5-30% of silicon-containing acrylic monomer.
2. 2. The high temperature heat expansion microsphere according to claim 1, wherein the silicon-containing acrylate monomer is silicon-based alkyl (meth) acrylate, and has the following structural formula: Wherein R 1 = H, methyl, R 2 ＝C n H 2n ,n≥0,R 3 ,R 4 ,R 5 = alkyl and a siloxane-containing derivative thereof.
3. 3. The high temperature heat expansion microsphere according to claim 2, wherein the silicon-based (meth) acrylic acid alkyl ester is any one or more of trimethylsilyl acrylate, trimethylsilyl methacrylate, triisopropylsilyl acrylate, methacryloxypropyl tris (trimethylsiloxy) silane, trimethylsilyl methacrylate, methylphenyl dimethylsilyl methacrylate and tributylsilyl 2-methyl-2-acrylate.
4. 4. The high temperature heat expansion microsphere according to claim 2, wherein the silicon-based (meth) acrylic acid alkyl ester is selected from any one or more of triisopropyl silicon-based methacrylate, triisopropyl silicon-based acrylate and methacryloxypropyl tris (trimethylsiloxy) silane.

Description

High-temperature thermal expansion microsphere Technical Field The invention relates to the field of manufacturing of expandable particles, in particular to a high-temperature thermal expansion microsphere. Background Thermally expandable microspheres having a structure in which a thermoplastic resin is used as a shell and a foaming agent is enclosed therein are generally called thermally expandable microcapsules. As the thermoplastic resin, vinylidene chloride copolymers, acrylonitrile copolymers, and acrylic acid ester copolymers can be generally used. In addition, as the foaming agent, mainly used are alkanes such as isooctane and isopentane. Various methods of preparing thermally expandable microspheres are disclosed in WO2007/142593A1、EP1149628A1、EP1811007A1、EP1302239A1、EP0486080、EPll2807B1、EP0348372A2、WO2004/0566549Al、US4287308 and EP1592733B1 et al. For thermally expandable microspheres it is important to have different initial foaming temperatures. Microspheres with different initial foaming temperatures have different application fields. Wherein, the high-temperature expandable microspheres, which generally have a higher initial foaming temperature of 150-180 ℃, can be applied to injection molding of thermoplastic materials, such as PP, PC, PA, ABS and other plastics. The microspheres are heated and expanded in the injection molding process, so that controllable foaming is realized, various thermoplastic materials are helped to generate uniform closed cell structures, the density is reduced, the surface structure is improved, and the stability of a finished product is improved. However, in the application process of hot injection molding, the microspheres are often broken in advance, so how to improve the breaking temperature and the heat-resistant durability of the microspheres is still an important subject in the industry. In order to improve the heat resistance and foaming temperature of the heat-expandable microspheres, in addition to selecting monomers with high glass transition temperature and improving the crosslinking degree of the shell layer, it has been found that the use of organosilicon monomers to modify the heat-expandable microspheres can improve the adhesion, heat resistance and solvent resistance. Patent CN100436562C, CN115895019a and patent CN109705392a disclose methods of thermally expanding microspheres modified by organosilicon compounds, increasing the degree of crosslinking of the shell by silane modification, and surface adsorption modification, respectively. However, these patents are all directed to the post-addition of silane in order to prevent premature hydrolysis of reactive functional groups such as methoxy and ethoxy groups of the silane, which are reactive and become uncontrollable. The mode of post-addition is adopted, so that the problems of more reaction procedures, long reaction time and the like exist, the relative addition amount is small, the organic silicon is low in proportion and is only distributed on the outer surface of the shell, and the ageing resistance and heat resistance of the organic silicon are limited. Patent CN107915799a discloses a method for modifying thermal expansion microsphere by copolymerizing with organosilicon monomer, after modification, the ageing resistance and ultraviolet resistance of thermal expansion microsphere can be raised. CN117069996B discloses a synthetic method of organosilicon modified epoxy resin, and the resin is introduced into the expanded microsphere, so that the high-temperature durability of the microsphere is improved. However, the two methods do not involve a further increase in the microsphere foaming temperature. Disclosure of Invention In view of the drawbacks of the prior art, it is an object of the present invention to provide a high temperature heat expandable microsphere which is halogen free and has a high maximum foaming temperature (typically >180 ℃) and a high expansion capacity. The invention provides a high-temperature thermal expansion microsphere, which comprises an olefinically unsaturated monomer (namely olefinically unsaturated monomer), a foaming agent, a crosslinking agent, an initiator, a dispersion stabilizer, a dispersion stabilizing auxiliary agent and a dispersion medium, wherein: The ethylenically unsaturated monomer comprises, by weight, 40-70% of acrylonitrile monomer, 10-30% of acrylic monomer, 10-30% of acrylamide monomer, 0-30% of acrylic monomer and 5-30% of silicon-containing acrylic monomer. The silicon-containing acrylic ester monomer participates in polymerization to form a microsphere shell, so that the foam breaking temperature, foam stabilizing capacity and heating durability of the microsphere are improved. Optionally, the acrylonitrile monomer is any one or more of acrylonitrile, methacrylonitrile, a-chloroacrylonitrile, a-ethoxyacrylonitrile, fumaronitrile and crotononitrile. Preferably, one or a mixture of acrylonitrile and methacrylonitrile. Alternatively, the acryli