Micro cement coating and preparation method thereof

Abstract

The invention relates to a micro cement coating and a preparation method thereof. The micro cement coating is prepared from the following raw materials in parts by weight: 30 to 40 parts of silane modified acrylic emulsion, 5 to 10 parts of tannic acid modified diatomite, 30 to 40 parts of white cement, 1 to 2 parts of coalescing agent, 1 to 2 parts of dispersing agent, 10 to 20 parts of ground calcium carbonate and 30 to 40 parts of water. The prepared micro cement coating film has the advantages of high tensile strength, high elongation at break, low water absorption and excellent performance as a waterproof coating.

Description

Technical Field

[0001] The invention relates to the field of coatings, in particular to a micro-cement coating and a preparation method thereof. Background Art

[0002] Cement is a gray, sticky, paste-like substance commonly seen on construction sites. It is used to cast the beams, slabs, columns and other structures of buildings. Because of its single color and poor decorative properties, it is basically only used as a base material and rarely as a surface material. With the rapid development of our society and the increasing living standards of people, people have put forward higher requirements for living conditions. High-performance decorative coatings can adapt to the functional requirements of buildings and meet the requirements of different bases, different grades and different decorative styles. They are relatively low in cost and relatively simple in construction technology. Therefore, they are becoming more and more popular in the construction market and have become an active field of research on architectural coatings. In recent years, architectural coatings have developed rapidly, with the continuous increase in the variety of coatings and the increase in consumption year by year. They occupy a very important position in the decoration and renovation projects of industrial and civil buildings, and are increasingly present in people's living environment.

[0003] Water leakage in buildings has become a serious problem that affects the strength and service life of buildings. The leakage is mainly concentrated in roofs, toilets, walls, basements, etc. The key to solving the problem of water leakage lies in the selection and use of waterproof materials. Among many waterproof materials, microcement waterproof coatings have the advantages of excellent waterproof effect, colorful decorative performance, green and pollution-free, so the coating has a very wide range of application scenarios and research value. However, there are still some problems in the actual application of microcement coatings. The water resistance or liquid penetration performance of microcement coatings is poor, and the traditional microcement coatings are prone to powdering and cracking after high temperature and alkaline treatment, resulting in damage to the microcement coating, and poor high temperature resistance and alkali resistance of microcement coatings. Summary of the invention

[0004] The purpose of the present invention is to provide a microcement coating and a preparation method thereof in order to overcome the defects of the above-mentioned prior art. The microcement coating prepared by the present invention has excellent mechanical properties, good waterproof effect and broad application prospects.

[0005] The present invention solves the above technical problems through the following technical solutions: The invention provides a micro-cement coating, and its raw materials include, by weight: 30-40 parts of silane-modified acrylic emulsion, 5-10 parts of tannic acid, tannic acid-modified diatomaceous earth, 30-40 parts of white cement, 1-2 parts of film-forming aid, 1-2 parts of dispersant, 10-20 parts of heavy calcium carbonate, and 30-40 parts of water; The silane-modified acrylic emulsion described above is prepared by the following method: (1) Methyl methacrylate, butyl acrylate, N-methylolacrylamide and an emulsifier are added to water and mixed and dispersed evenly to obtain a pre-emulsion; (2) Methyl methacrylate, butyl acrylate, N-methylolacrylamide, vinyltrimethoxysilane and an emulsifier are added to water, mixed and dispersed evenly, disodium hydrogen phosphate is added to adjust the pH value of the mixed system to 7.3 - 7.6, and tert-butyl hydroperoxide is added for emulsion polymerization reaction; (3) A mixture of the pre-emulsion and ammonium persulfate is slowly added dropwise, and polymerization reaction is carried out again to obtain the silane-modified acrylic emulsion.

[0006] Among them, the emulsifier described above can be various emulsifiers commonly used in the art, and preferably is ammonium alkylphenol polyoxyethylene ether sulfate.

[0007] Preferably, the raw materials of the microcement coating are composed of the following components in parts by weight: 30 - 40 parts of silane-modified acrylic emulsion, 5 - 10 parts of tannic acid-modified diatomite, 30 - 40 parts of white cement, 1 - 2 parts of film-forming aid, 1 - 2 parts of dispersant, 10 - 20 parts of heavy calcium carbonate, and 30 - 40 parts of water.

[0008] Among them, in step (2), the temperature of the emulsion polymerization reaction is preferably 60 - 70 °C; in step (2), the temperature of the re-polymerization reaction is preferably 75 - 80 °C.

[0009] The tannic acid-modified diatomite described above is preferably prepared by the following method: Diatomite is added to a tannic acid solution, and then ferric chloride solution is added for reaction, followed by centrifugal washing and drying to obtain the tannic acid-modified diatomite.

[0010] The white cement described above is preferably white Portland cement.

[0011] Among them, the film-forming aid has no particular limitation and can be dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol butyl ether, alcohol ester twelve, etc., such as DPM, DPNB, BCS of Dow, and texanol of Eastman.

[0012] Among them, the dispersant has no particular limitation, and preferably is BYK-2155 dispersant.

[0013] The present invention also provides a preparation method of the above microcement coating, which includes the following steps: Add the silane-modified acrylic emulsion, tannic acid-modified diatomite, film-forming aid, dispersant, and water into a stirrer, stir evenly, and then add white cement and heavy calcium carbonate, and disperse evenly at high speed.

[0014] Among them, the rotation speed of the high-speed dispersion is preferably 2000 - 2500 r / min.

[0015] In a preferred embodiment of the present invention, the microcement coating may further include various additives.

[0016] If additives are included, they can be added in the last step of the preparation method.

[0017] Coating film preparation: First, apply paraffin oil to the mold, and then slowly pour the prepared microcement coating into the mold to a thickness of about 1.0 mm; after its surface dries, slowly pour the microcement coating again and gently scrape it flat, and the total thickness of the coating film is about 1.5 ± 0.1 mm.

[0018] Compared with the prior art, the present invention has the following beneficial effects: In view of the deficiencies of cement, the present invention modifies cement and proposes a preparation method for a microcement coating. The present invention uses a silane-modified acrylic emulsion as the polymer matrix of the cement coating, and adds tannic acid-modified diatomaceous earth. During the film-forming process of the coating, the cross-linking and curing effect of the active groups of organosilicon in the emulsion is strengthened, so that the surface molecules of the whole coating form a network structure, and thus the surface molecules of the coating film are more closely connected. The tensile strength of the microcement coating film prepared by the present invention reaches more than 3.12 Mpa, the elongation at break reaches more than 259%, and the water absorption rate is less than 7.84%, and it has excellent waterproof coating performance. Specific embodiments

[0019] The present invention will be described in detail below with reference to specific embodiments.

[0020] Storage stability test: Observe whether there is sedimentation and deterioration after storing the pigment at 20 °C and 40 °C for 10 weeks, and use it for the color change of the dried coating.

[0021] Freeze-thaw stability test method: First, measure the pH of the coating (measured at 23 °C) and measure its viscosity under shear loads of 10 s-1, 100 s-1 and 1000 s-1

measured at 23 °C using a rotational viscometer (Rheolab QC equipment from Anton Paar, with a C-LTD80 / QC adjustment system)

[0022] Water absorption rate: Under standard atmospheric pressure, the lower the water absorption rate of the coating film, the better the waterproof effect. The specific calculation steps are as follows: Prepare the microcement coating into a film, weigh it after demolding, and record the mass as m1. Then soak the film in deionized water, take it out after 24 h, blot the water on the surface of the coating film with absorbent paper, and weigh it on an electronic balance, and record the mass as m2. The water absorption rate of the film is (m2 - m1) / m1 × 100%. Example 1

[0023] The raw materials of the microcement coating in this embodiment include, by weight: 30 parts of silane-modified acrylic emulsion, 6 parts of tannic acid-modified diatomite, 35 parts of white cement, 1 part of film-forming aid, 1 part of dispersant, 12 parts of heavy calcium carbonate, and 35 parts of water; the dispersant is BYK-2155 dispersant, and the film-forming aid is dipropylene glycol methyl ether; the white cement is white Portland cement.

[0024] Among them, the silane-modified acrylic emulsion is prepared by the following method: (1) Add 40 g of methyl methacrylate, 20 g of butyl acrylate, 4 g of N-hydroxymethyl acrylamide, and 0.5 g of emulsifier (alkylphenol polyoxyethylene ether ammonium sulfate) to 100 g of water, and mix and disperse evenly to obtain a pre-emulsion; (2) Add 40 g of methyl methacrylate, 20 g of butyl acrylate, 4 g of N-hydroxymethyl acrylamide, 5 g of vinyltrimethoxysilane, and 0.5 g of emulsifier (alkylphenol polyoxyethylene ether ammonium sulfate) to 100 g of water, mix and disperse evenly, add disodium hydrogen phosphate to adjust the pH value of the mixed system to 7.3, and add 0.1 g of tert-butyl hydroperoxide to carry out emulsion polymerization reaction at 60 °C; (3) Slowly dropwise add the mixture of the pre-emulsion in step (1) and 0.1 g of ammonium persulfate, and carry out polymerization reaction at 75 °C to obtain the silane-modified acrylic emulsion.

[0025] The tannic acid-modified diatomite is prepared by the following method: Add 50 g of diatomite to 60 g of tannic acid solution, then add 10 g of ferric chloride solution, adjust the pH to 8.5, react at 65 °C for 8 hours, centrifuge and wash, and dry to obtain the tannic acid-modified diatomite.

[0026] The preparation method of the microcement coating includes the following steps: Add the silane-modified acrylic emulsion, tannic acid-modified diatomite, film-forming aid, dispersant, and water to a stirrer, stir evenly, then add white cement and heavy calcium carbonate, and disperse evenly at high speed (2000 r / min).

[0027] Coating film preparation: First, apply paraffin oil to the mold, then slowly pour the prepared microcement coating into the mold to a thickness of about 1.0 mm; after its surface dries, slowly pour the microcement coating again and gently scrape it flat, and the total thickness of the coating film is about 1.5 mm.

[0028] After storing the microcement coating prepared in this embodiment for 10 weeks, no sedimentation and deterioration were observed, and the viscosity basically remained unchanged after the above freeze-thaw cycle test. The tensile strength of the prepared coating film is 3.12 Mpa, the elongation at break reaches 259%, and the water absorption rate is 7.63%. Example 2

[0029] The raw materials of the microcement coating in this embodiment include, by weight: 40 parts of silane-modified acrylic emulsion, 10 parts of tannic acid-modified diatomite, 39 parts of white cement, 2 parts of film-forming aid, 2 parts of dispersant, 20 parts of heavy calcium carbonate, and 40 parts of water; the dispersant is BYK-2155 dispersant, the film-forming aid is alcohol ester twelve; the white cement is white Portland cement.

[0030] Among them, the silane-modified acrylic emulsion is prepared by the following method: (1) Add 40 g of methyl methacrylate, 20 g of butyl acrylate, 4 g of N-hydroxymethyl acrylamide, and 0.5 g of emulsifier (alkylphenol polyoxyethylene ether ammonium sulfate) to 100 g of water, and mix and disperse evenly to obtain a pre-emulsion; (2) Add 40 g of methyl methacrylate, 20 g of butyl acrylate, 4 g of N-hydroxymethyl acrylamide, 5 g of vinyltrimethoxysilane, and 0.5 g of emulsifier (alkylphenol polyoxyethylene ether ammonium sulfate) to 100 g of water, mix and disperse evenly, add disodium hydrogen phosphate to adjust the pH value of the mixed system to 7.3, and add 0.1 g of tert-butyl hydroperoxide to carry out emulsion polymerization reaction at 65 °C; (3) Slowly drop the mixture of the pre-emulsion in step (1) and 0.1 g of ammonium persulfate, and carry out polymerization reaction at 80 °C to obtain the silane-modified acrylic emulsion.

[0031] The tannic acid-modified diatomite is prepared by the following method: Add 50 g of diatomite to 60 g of tannic acid solution, then add 10 g of ferric chloride solution, adjust the pH to 8.5, react at 65 °C for 8 hours, centrifuge and wash, and dry to obtain the tannic acid-modified diatomite.

[0032] The preparation method of the microcement coating includes the following steps: Add the silane-modified acrylic emulsion, tannic acid-modified diatomite, film-forming aid, dispersant, and water to a stirrer, stir evenly, and then add white cement and heavy calcium carbonate, and disperse evenly at high speed (2500 r / min).

[0033] Coating film preparation: First, apply paraffin oil to the mold, and then slowly pour the prepared microcement coating into the mold to a thickness of about 1.0 mm; after its surface dries, slowly pour the microcement coating again and gently scrape it flat, and the total thickness of the coating film is about 1.5 mm.

[0034] After storing the microcement coating prepared in this embodiment for 10 weeks, no sedimentation and deterioration were observed, and the viscosity basically did not change after the above freeze-thaw cycle test. The tensile strength of the prepared coating film is 3.23 Mpa, the elongation at break reaches 262%, and the water absorption rate is 7.84%.

[0035] It must be emphasized that the above detailed description is a specific description of the feasible embodiments of the present invention, but the embodiments are not intended to limit the patent scope of the present invention. Any equivalent implementation or change made without departing from the technical spirit of the present invention shall be included in the patent scope of the present invention.

Claims

1. A microcement coating, the raw materials of which include by weight: 30-40 parts of silane-modified acrylic emulsion, 5-10 parts of tannic acid, tannic acid-modified diatomaceous earth, 30-40 parts of white cement, 1-2 parts of film-forming aid, 1-2 parts of dispersant, 10-20 parts of heavy calcium carbonate, and 30-40 parts of water; The silane-modified acrylic emulsion is prepared by the following method: (1) adding methyl methacrylate, butyl acrylate, N-hydroxymethyl acrylamide and an emulsifier into water, mixing and dispersing them uniformly to obtain a pre-emulsion; (2) adding methyl methacrylate, butyl acrylate, N-hydroxymethyl acrylamide, vinyl trimethoxy silane and an emulsifier into water, mixing and dispersing them uniformly, adding disodium hydrogen phosphate to adjust the pH value of the mixed system to 7.3-7.6, and adding tert-butyl hydroperoxide to carry out emulsion polymerization reaction; (3) slowly dropping the mixture of the pre-emulsion and ammonium persulfate, and performing polymerization reaction again to obtain the silane-modified acrylic emulsion.

2. The microcement coating according to claim 1, characterized in that: The emulsifier is preferably alkylphenol polyoxyethylene ether ammonium sulfate.

3. The microcement coating according to claim 1, characterized in that: The raw materials of the microcement coating are composed of the following components by weight: 30-40 parts of silane-modified acrylic emulsion, 5-10 parts of tannic acid, tannic acid-modified diatomaceous earth, 30-40 parts of white cement, 1-2 parts of film-forming aid, 1-2 parts of dispersant, 10-20 parts of heavy calcium carbonate and 30-40 parts of water.

4. The microcement coating according to claim 1, characterized in that: In step (2), the temperature of the emulsion polymerization reaction is preferably 60-70°C; in step (2), the temperature of the secondary polymerization reaction is preferably 75-80°C.

5. The microcement coating according to claim 1, characterized in that: The tannic acid modified diatomaceous earth is preferably prepared by the following method: adding diatomaceous earth into a tannic acid solution, then adding a ferric chloride solution for reaction, centrifuging and washing, and drying to obtain the tannic acid modified diatomaceous earth.

6. The microcement coating according to claim 1, characterized in that: The white cement is white silicate cement.

7. The microcement coating according to claim 1, characterized in that: The film-forming aid is one or more of dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol butyl ether and alcohol ester twelve.

8. The microcement coating according to claim 1, characterized in that: The dispersant is BYK-2155 dispersant.

9. A method for preparing a microcement coating as claimed in any one of claims 1 to 8, comprising the following steps: adding silane-modified acrylic emulsion, tannic acid-modified diatomaceous earth, film-forming aid, dispersant and water into a stirrer, stirring evenly, then adding white cement and heavy calcium carbonate, and dispersing evenly at high speed.

10. The preparation method according to claim 9, characterized in that: The rotation speed of the high-speed dispersion is 2000-2500 r / min.