Unmodified silica sol/polyacrylate core-shell emulsion and preparation method thereof

Abstract

The invention discloses a method for preparing an unmodified silica sol / polyacrylate core-shell emulsion. According to the method, commercially available alkaline silica sol and acrylate monomers are adopted as main raw materials, tedious surface modification treatment of nanoparticles is not needed, the monomers are subjected to in-situ polymerization on the surfaces of the unmodified SiO2 particles under the action of a reactive emulsifier so as to obtain a seed emulsion using SiO2 as cores and then acrylate shell polymerization is carried out on the surfaces of emulsifiable particles in the seed emulsion so as to synthesize the unmodified silica sol / polyacrylate core-shell emulsion with excellent performance. The method is simple in production process and the synthesis is rapid; the film of the synthesized unmodified silica sol / polyacrylate core-shell emulsion has the performances of high transparency, water resistance, high hardness, strong adhesion force as well as good stain resistance, heat resistance, acid and alkaline resistance, environmental friendliness, flame retardancy and the like and is high in performance and low in cost, is novel and environment friendly and can be widely applied in the field of multiple coatings.

Description

technical field [0001] The invention belongs to the field of environment-friendly nano-core-shell aqueous emulsion, and in particular relates to an unmodified silica sol / polyacrylate core-shell 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, th...

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Problems solved by technology

[0005] 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 powder needs to be subjected to complicated hydrophobic treatment during the preparation process, and the requirements for dispersion equipment are high. , 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.

[0006] 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

[0007] 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

[0008] 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 Nano-core-shell composite emulsion as the core, but there are still cumbersome modification process problems such as the need to modify the silica sol first

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