A kind of styrene-acrylic emulsion for modified cement mortar and preparation method thereof

Abstract

The invention relates to a styrene-acrylic emulsion for modified cement mortar and a preparation method thereof. The styrene-acrylic emulsion for modified cement mortar consists of the following components and components in parts by weight: styrene 24-49, butyl acrylate 49-74 , Functional monomer 2~6, anionic emulsifier 0.5~1, nonionic emulsifier 0.5~1.5, initiator 0.4~0.75, pH buffer 0.3~0.5, stabilizer 0~2, pH regulator amount, water 100 ~150; Wherein, the adding amount of pH adjuster satisfies the pH of styrene-acrylic emulsion for modified cement mortar between 7~8. Compared with the prior art, the polymer emulsion obtained in the present invention can maintain stability in cement mortar, and make the modified mortar have better performance, which solves the problem that the low glass transition temperature polymer emulsion in the previous research is easy to use in cement mortar. Demulsification problem.

Description

technical field [0001] The invention belongs to the technical field of building materials, and in particular relates to a styrene-acrylic emulsion for modified cement mortar and a preparation method thereof. Background technique [0002] Ordinary cement-based materials have low bond strength, high brittleness, poor impermeability, crack resistance, and frost resistance. In response to these shortcomings of common cement-based materials, people began to explore the use of polymers and cement blends to improve the performance of common cement-based materials. After adding polymer materials, many properties of cement-based materials such as strength, deformation ability, bonding performance, waterproof performance, durability, etc. will be improved, and the degree of improvement is related to the poly-ash ratio (the weight of the solid polymer and the weight of the cement) Ratio), the type and performance of the polymer have a lot to do with it. [0003] There are many studie...

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Problems solved by technology

[0005] Chinese patent CN101062850A discloses a flexible acrylate emulsion for mortar, which mainly emphasizes that it can improve the bonding strength of cement products, but does not involve the compatibility of polymer emulsion and mortar and the influence of polymer emulsion on other properties of mortar

[0006] Chinese patent CN101386663A discloses a multifunctional acrylic emulsion. The prepared emulsion claims to improve the performance of mortar, but there is no data in its content that the emulsion can be successfully used in mortar, only the performance data of preparing waterproof coating

However, the workability with the mortar is not explained (that is, how to ensure the stability of the emulsion in the mortar), cohesiveness, water resistance and other properties are not explained. The prepared mortar formula is not explained, and there is no way to compare the prepared emulsion comprehensively. performance

And the process used is the core-shell emulsion polymerization process. Although the core-shell emulsion polymerization can design latex particles with different structures according to the performance requirements, the structure and shape of the emulsion particles cannot be accurately controlled.

And because there are many factors and influencing factors to be designed, how to accurately control the influence of various factors in large-scale production is a big challenge

[0009] Chinese patent CN101687952A discloses a water-based synthetic resin emulsion for cement mortar admixture, re-emulsifying water-based synthetic resin emulsion powder for cement mortar admixture and cement mortar admixture using it. The sand-cement ratio is 3 and the water-cement ratio is 0.7, under the condition that the poly-ash ratio is 0.1, the initial fluidity of the mortar is not high, only 170mm, which shows that the polymer emulsion and latex powder disclosed in the patent are not very stable in the mortar (so such a high water content is used). gray ratio), and such a high water-cement ratio will cause a serious decline in other properties of the mortar, although the mechanical properties of the mortar such as compression and flexural resistance are not given in this patent

[0010] It can be seen that the current research on polymer emulsions for modified mortar in my country is not perfect, and there are still many problems in the developed polymer emulsions.

Moreover, the most important thing is that in the above published patents, there is no specific mention of how to select the proportion of monomer components and the process so that the synthesized emulsion can be used stably in mortar

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