Method for preparing silicone acrylic emulsion with high solid content and high silicon content

Abstract

The invention relates to a method for preparing a silicone acrylic emulsion with high solid content (of over 50 percent), high organic silicon content (of over 15 percent) and low emulsifier consumption (of less than 2.5 percent), in particular a silicone acrylic emulsion for preparing high-grade exterior wall coating materials. The method comprises steps of preparing a vinyl polysiloxane emulsion by using octamethylcyclotetrasiloxane, tetravinyl tetramethylcyelo tetrasiloxane, dodecylbenzene sulfonic acid, sodium dodecyl benzene sulfonate, a non-ionic emulsifier NP-40 and deionized water through acid catalyzed ring opening, and performing silicone acrylic emulsion copolymerization of the vinyl polysiloxane emulsion and acrylic monomers in the presence of a thermal initiator to prepare the stable silicone acrylic emulsion with high solid content, high organic silicon content and low emulsifier consumption. By the method, problems that the silicon content cannot be improved substantially, the solid content is low and the emulsifier consumption is high in the preparation of the silicone acrylic emulsion are effectively solved. The silicone acrylic emulsion has excellent weather resistance, stain resistance, water resistance and the like, and has high cost performance; and the application range of the silicone acrylic emulsion is greatly widened.

Description

technical field [0001] The invention relates to a method for preparing a silicon-acrylic emulsion, in particular to a method for preparing a silicon-acrylic emulsion with a high solid content (greater than 50%), a high organic silicon content (greater than 15%) and a low amount of emulsifier (less than 2.5%) , especially the silicone acrylic emulsion that can be used in the preparation of high-grade exterior wall paints. Background technique [0002] Polyacrylate emulsion is widely used in the production of architectural latex coatings due to its good film-forming properties, high strength and strong adhesion, but it also has disadvantages such as weather resistance, water resistance and stain resistance, which limit its further development. application. With people's requirements for greening, high performance and high functionality of coating products, acrylic latex coatings have been slow to meet the requirements, especially as building exterior wall coatings, they must ...

AI Technical Summary

Problems solved by technology

CN1629202A discloses using vinyltriethoxysilane, acrylic acid and acrylate as monomers, under the protection of protective colloid and hydrolysis inhibitor, a kind of core-shell structure silicon-acrylic emulsion with organic silicon content greater than 15% is synthesized, However, the solid content is also lower than 50%, and the amount of emulsifier reaches 8%, and the amount of protective colloid and hydrolysis inhibitor is also high, which will seriously affect the water resistance of the coating film and is not conducive to environmental protection.

However, the solid content of its products is only between 36% and 45%, and the amount of emulsifier is also relatively high.

Patent CN101798369A also discloses a method for preparing a high-silicon-content silicon-acrylic emulsion. The silicone content in the obtained emulsion accounts for more than 10% of the emulsion system. It uses an alkoxysilane coupling agent as the silicone monomer. Inhibitors and redox initiators are used to implement, but the solid content is also below 50%, and some additives are also introduced, which is not conducive to the improvement of comprehensive performance

Wang Guojian and others used the hydrolysis inhibition method in the "Development of High Silicon Content Organosilicon-Acrylic Emulsion" published in "Shanghai Paint" Volume 43, Issue 2, January 2005, using vinyl siloxane monomers that are not easily hydrolyzed and Emulsion polymerization of acrylate monomers to obtain a silicone-acrylate emulsion with a silicone content of 20%, but the amount of emulsifier is large and the solid content is low

Tang Minfeng et al. published "Synthesis and Properties of Branched Silicone / Acrylate Copolymer Emulsion" published in "Fine Chemical Industry" in January 2007, Volume 24, Issue 1, using reactive silicone monomers with branched structures and Emulsion copolymerization of MPS silane coupling agent and acrylate monomer to synthesize a stable high-silicon-content silicon-acrylic emulsion with a maximum silicone content of 10%, but the same problem exists, and the solid content is less than 50%.

In addition, some other researchers have also done similar research work, such as "Preparation of High Silicon Content VTES / St / MMA Copolymer Emulsion at Room Temperature" published by Yin Changjie et al. "Research"; Ge Chengyue et al. published "Low Temperature Synthesis and Stability of Silicon-Acrylic Core / Shell Emulsion" in "Macromolecular Materials Science and Engineering", Volume 25, Issue 4, April 2009; Hu Zhongyu in "New Chemical Materials "The Development of Silicone-Acrylic Emulsion with High Silicon Content" published in Volume 36, Issue 1, January 2008, all synthesized silicone-acrylic emulsions with a silicone content between 10% and 15%, but there are Same problem: lower solid content, higher dosage of some emulsifiers

[0005] The existing technology shows that when the organic silicon content is low, the performance improvement of the silicone-acrylic emulsion is limited, and the modification effect cannot be achieved; if the amount of emulsifier is too small, when the organic silicon content or the solid content is increased, or both When the content of silicone is increased, the stability of the emulsion becomes poor and it is easy to coagulate; but if the content of organic silicon is increased to reduce the solid content, it will increase the cost of production and transportation, and limit the further wide application of silicone acrylic emulsion; the amount of emulsifier is large, and to a certain extent It affects the hydrophobic effect of the silicone monomer, resulting in a decrease in the water resistance of the emulsion coating film

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