Silica sol/silicone acrylate core-shell nanocomposite emulsion and preparation method thereof

Abstract

The invention discloses a silica sol / silicone acrylate core-shell nanocomposite emulsion and a preparation method thereof. The preparation method comprises the steps of with alkali silica sol sold on the market and acrylic monomers as main raw materials, enabling the monomers to be subjected to in-situ polymerization on the surfaces of unmodified SiO2 particles under the action of a reactive emulsifier to obtain a seed emulsion; and introducing organic vinylsilane (allylsilane) during polymerization reaction of acrylic ester at a shell layer, and enabling organic vinylsilane (allylsilane) and the acrylic monomers to be subjected to main-chain copolymerization on a newly-generated composite emulsion particle shell layer to form a chain segment with certain organic silicon with hydrophobicity and high bonding energy to obtain the silica sol / silicone acrylate core-shell nanocomposite emulsion. The method is simple in production process and high in synthesis speed; and the obtained composite emulsion is excellent in performance, environment-friendly, flame-retardant and good in transparency and has the performances such as strong water resistance, stain resistance, heat resistance, acid resistance, alkali resistance and the like same as those of a silicone-acrylate emulsion. The silica sol / silicone acrylate core-shell nanocomposite emulsion can be widely applied to the field of various coatings such as high-grade building coatings, textile treating agents, adhesives, electronic packaging materials, metal protective coatings and the like.

Description

technical field [0001] The invention belongs to the field of nano-core-shell aqueous emulsions, and in particular relates to a silica sol / silicone-acrylic nano-core-shell composite emulsion and a preparation method thereof. Background technique [0002] Inorganic / organic nanocomposite emulsion is a hot spot in the research of coating film-forming substances in recent years. Due to the introduction of rigid inorganic components, the hardness of the film is greatly improved, and it can overcome many problems such as "hot stickiness, cold brittleness" and poor UV aging resistance of simple polymers. However, the water resistance, acid and alkali resistance, stain resistance and scrub resistance of the coating film have also been greatly improved, and it has the characteristics of non-toxic environmental protection and mild reaction conditions. [0003] In recent years, with the wide application of nanotechnology and the improvement of the polymerization process, the in-situ pol...

AI Technical Summary

Problems solved by technology

[0004] Chinese patent application "Nano silica modified elastic acrylate copolymer emulsion" (application number: 200810019036.9 publication date: 2008-07-09) discloses that the emulsion is made of nano-SiO2 modified by organosilicon or metal crosslinking. 2 It is prepared by in-situ polymerization with acrylate monomer, and the strength, water resistance, weather resistance and stain resistance of the coating film are all improved to a certain extent, but the preparation process requires complex hydrophobic treatment of the powder, which requires high dispersion equipment. , some need to use organic solvents, and the stability needs to be further improved. The silicon content in the emulsion is generally not more than 5%, and the improvement of the emulsion performance is limited.

[0005] The composite emulsion of the Chinese patent "A Preparation Method of Nano-Silicon Dioxide / Polyacrylate Composite Emulsion" (Patent No.: 201010524511.5 Publication Date: 2011-04-27) is composed of tetraethyl orthosilicate, silane coupling agent and acrylate The emulsion is prepared by in-situ copolymerization of monomers. This emulsion effectively avoids the problem of "secondary agglomeration" of traditional nano-silica in the emulsion polymerization process. The stability is improved to a certain extent, and the heat resistance of the coating film is excellent. Hydrolysis and coupling treatment of ethyl orthosilicate are required before polymerization, but there are still many disadvantages such as complex and cumbersome process and difficult control of reaction conditions, which cannot meet the actual production application

[0006] Chinese patent application "Nano silica sol / acrylate composite emulsion and its preparation method" (application number: 200910046420.2 publication date: 2009-08-05) uses alkyl alcohol solvent to inhibit the hydrolysis of silicon hydroxyl group, and polymerizes with acrylate monomer Composite emulsion, the composite latex particle is a nano-core-shell structure with silica particles as the core and acrylate as the shell, but there are still many shortcomings, such as the particle size of the composite latex particle is too large, the diameter is 150-200nm, the silicon content The maximum does not exceed 10%, failing to maximize the characteristics of nanomaterials and reduce costs

[0007] In the preparation process of the Chinese patent application "a silica sol / acrylate nano-core-shell composite emulsion and its preparation method" (application number: 201310481166.5 publication date: 2014-03-26), the nano-silica sol was first chelated with titanium treatment, under the action of the initiator, the environmentally friendly reactive emulsifier and acrylate monomer polymerize in situ on the surface of the nano-silica particles to form SiO 2 It is a nano-core-shell composite emulsion with small particle size, high coverage and high silicon content, but the water resistance of the emulsion is still not ideal compared with silicon acrylic emulsion

However, the preparation process first needs to modify the silica sol with a silane coupling agent, and needs to use isopropanol, tert-butanol, etc. as co-solvents; in addition, the seed emulsion and the shell emulsion also need to be pre-emulsified, and the process is relatively complicated. It is cumbersome, and the modified part of silica sol is not easy to control, and it is easy to gel

Organic modification concentrated on the outermost layer of the shell also has the disadvantage of being easy to gel during polymerization

Images