Modified waterproof coating and preparation method thereof

Abstract

The invention discloses a modified waterproof coating. Comprising the following components in parts by weight: 60-110 parts of cement; 60 to 160 parts of an acrylate polymer emulsion; 20 to 50 parts of modified diatomite; 20 to 50 parts of silicon nitride; 20 to 30 parts of talcum powder; 5 to 15 parts of a defoaming agent; and 2-10 parts of a silane coupling agent. The waterproof coating can better adapt to deformation of a cement substrate through the modified diatomite, the adaptability of the waterproof coating to different base layers is improved, and the permeation resistance of alkaline substances generated by wall curing is increased. The modified waterproof coating permeates into gaps of a wall surface, when the modified waterproof coating meets alkaline substances on the wall surface, tetraethyl orthosilicate of the modified waterproof coating is rapidly hydrolyzed under the catalysis of alkali to generate nano-scale silicon dioxide particles,-OH groups on the surfaces of the nano-scale silicon dioxide particles react with active Si-H bonds in hydrogen silicone oil, and the modified waterproof coating is formed. Therefore, hydrophobic groups are connected with the surfaces of nano silicon dioxide particles, the protection wall is florified, and the structure of a paint substrate is broken.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly relates to a modified waterproof coating and a preparation method thereof, which are particularly suitable for waterproof coatings on cement-based substrates. Background Art

[0002] Polymer cement-based waterproof coatings are widely used in waterproof projects such as building walls and roofs due to their good waterproof performance and construction convenience.

[0003] However, during the use of polymer cement-based waterproof coatings, the following problems often exist: Uneven flow and dripping during the construction of the waterproof coating Polymer cement-based waterproof coatings usually contain silicate components, which form a relatively viscous gel state before coating. When applying the coating by means such as dipping, spraying, and painting, the microstructure inside the polymer cement-based waterproof coating slurry is damaged, and the rheology of the coating becomes complex, resulting in problems such as uneven flow and dripping of the coating on vertical surfaces during construction. This non-uniformity not only impairs the aesthetics of the coating but also reduces its protective ability.

[0004] Poor alkali resistance of the waterproof coating Cement is one of the main materials for building walls, and its main components include various alkaline oxides such as calcium oxide (CaO) and magnesium oxide (MgO). During the hydration process of cement, hydroxide ions (OH - - ) are released, making the wall surface alkaline. These alkaline substances form salting-out phenomena on the surface as they migrate and evaporate with water molecules, appearing in the form of flocculent spots. Wall efflorescence changes the pH value of the wall substrate, damaging the adhesion between the coating and the wall. Alkaline substances will form a weak layer between the coating and the substrate, resulting in the coating being unable to adhere firmly to the wall surface and being prone to peeling, falling off, etc.

[0005] After the integrity of the coating is damaged, its waterproof performance will also be greatly reduced. Especially in some cases where the quality of cement is unstable or high-alkali cement is used, the alkalinity of the wall will be higher.

[0006] Therefore, there is an urgent need for a modified waterproof coating that is easy to construct and has good alkali resistance. Summary of the Invention

[0007] Aiming at the problems of uneven flow, dripping during the construction of the waterproof coating and poor alkali resistance in the prior art, the present invention provides a modified waterproof coating.

[0008] The present invention provides a modified waterproof coating, which is characterized in that the waterproof coating comprises the following components in parts by weight: Cement 60 - 110 parts; 60 - 160 parts of acrylate polymer emulsion; 20 - 50 parts of modified diatomaceous earth; 20 - 50 parts of silicon nitride; 20 - 30 parts of talcum powder; 5 - 15 parts of defoamer; 2 - 10 parts of silane coupling agent.

[0009] Preferably, the method for preparing the modified diatomaceous earth is as follows: Perform pretreatment operations of drying, grinding, and sieving on the diatomaceous earth powder to obtain diatomaceous earth powder; Drop hydrogen silicone oil and tetraethyl orthosilicate into absolute ethanol respectively, and continuously stir; Add the pretreated diatomaceous earth powder into absolute ethanol, stir well, add nitric acid to adjust the pH to 4 to obtain a mixture; Continuously stir the mixture for 2 h, so that hydrogen silicone oil, tetraethyl orthosilicate and diatomaceous earth are in full contact, and then centrifuge to obtain modified diatomaceous earth.

[0010] Preferably, the mass ratio of the hydrogen silicone oil to the tetraethyl orthosilicate is 2 - 5:1.

[0011] Preferably, the acrylate polymer emulsion is made from ethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, and toluene diisocyanate as raw materials.

[0012] Preferably, the cement is obtained by mixing ordinary Portland cement PO32.5 and fly ash Portland cement PF42.5 in a mass ratio of 1:2 - 3.

[0013] Preferably, the silane coupling agent is aminopropyltriethoxysilane or γ - glycidoxypropyltrimethoxysilane.

[0014] Preferably, the defoamer is emulsified methyl silicone oil.

[0015] The present invention provides a method for preparing a modified waterproof coating, which includes the following steps: 1) Mix cement, silicon nitride, and talcum powder, and stir to form a mixture at a stirring speed of 150 rpm for 2 min; 2) Prepare modified diatomaceous earth; 3) Disperse the mixture and the modified diatomaceous earth in the acrylate polymer emulsion, heat to 70 - 90 °C, stir at a stirring speed of 300 - 500 rpm for 5 min, add the defoamer and the silane coupling agent, and react for 3 min; 4) Cool to room temperature and stop stirring to obtain the modified waterproof coating.

[0016] The technical effect of the present invention lies in: The modified diatomite enables the waterproof coating to better adapt to the deformation of the cement base, and it is not easy to cause the waterproof layer to rupture due to slight displacement or expansion and contraction of the base, improving the adaptability of the waterproof coating to different substrates. In addition, the unique microporous structure of diatomite can form a tortuous channel in the coating, increasing the penetration resistance of the alkaline substances generated during the wall curing.

[0017] The modified waterproof coating penetrates into the wall voids. When it encounters the alkaline substances on the wall, tetraethyl orthosilicate in the modified waterproof coating is rapidly hydrolyzed under the catalysis of alkali to generate nano-scale silica particles. The -OH groups on the surface of these nano-silica particles react with the active Si-H bonds in the hydrogen silicone oil, so that the hydrophobic groups are connected to the surface of the nano-silica particles, protecting the wall from powdering and damaging the coating base structure. In addition, when the alkaline substances contact the coating, the nano-silica particles formed after the hydrolysis of tetraethyl orthosilicate in the pores of diatomite seal the pores of diatomite, further preventing the alkaline substances from damaging the coating. Detailed implementation manners

[0018] For the convenience of understanding the present application, the present application will be described more comprehensively below. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure content of the present application more thorough and comprehensive.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0020] In the present application, among the technical features described in an open-ended manner, it includes a closed technical solution composed of the listed features, and also includes an open technical solution containing the listed features.

[0021] In the present application, regarding the numerical range, unless otherwise specified, the above numerical range is considered continuous and includes the minimum value and the maximum value of this range, as well as each value between such minimum value and maximum value. Further, when the range refers to an integer, it includes each integer between the minimum value and the maximum value of this range. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0022] Regarding the percentage content involved in the present application, unless otherwise specified, for solid-liquid mixing and solid-solid mixing, it refers to the mass percentage, and for liquid-liquid mixing, it refers to the volume percentage.

[0023] In this application, unless otherwise specified, the percentage concentration refers to the final concentration. The final concentration refers to the proportion of the added component in the system after adding the component.

[0024] In this application, unless otherwise specified, the temperature parameter allows both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument.

[0025] The "particles" mentioned in this application, or substances with a defined particle size distribution, do not necessarily have a spherical shape and may also be irregular. They can be primary particles or secondary particles. The particle size of irregular particles is calculated as the average of their maximum diameter and minimum diameter.

[0026] Example 1 Take 60 parts of cement, 50 parts of silicon nitride, and 20 parts of talcum powder, mix them, and stir to form a mixture at a stirring speed of 150 rpm for 2 minutes; Perform pre-treatment operations of drying, grinding, and sieving on 50 parts of diatomaceous earth to prepare diatomaceous earth powder; drop 10 parts of hydrogen silicone oil and 50 parts of tetraethyl orthosilicate into anhydrous ethanol respectively, and continuously stir; slowly add the pre-treated diatomaceous earth powder into anhydrous ethanol, stir well, add nitric acid to adjust the pH to 4 to obtain a mixture; continuously stir the mixture for 2 hours to allow hydrogen silicone oil, tetraethyl orthosilicate to fully contact with the diatomaceous earth, and then centrifuge to obtain modified diatomaceous earth.

[0027] Disperse the above mixture and modified diatomaceous earth in 160 parts of acrylate polymer emulsion, heat to 70 - 90 °C, stir at a speed of 300 - 500 rpm for 5 minutes, add 10 parts of defoamer and 10 parts of silane coupling agent, and react for 3 minutes; cool to room temperature and stop stirring to obtain the waterproof coating of this example.

[0028] Example 2 Take 75 parts of cement, 50 parts of silicon nitride, and 20 parts of talcum powder, mix them, and stir to form a mixture at a stirring speed of 150 rpm for 2 minutes; Perform pre-treatment operations of drying, grinding, and sieving on 50 parts of diatomaceous earth to prepare diatomaceous earth powder; drop 10 parts of hydrogen silicone oil and 20 parts of tetraethyl orthosilicate into anhydrous ethanol respectively, and continuously stir; slowly add the pre-treated diatomaceous earth powder into anhydrous ethanol, stir well, add nitric acid to adjust the pH to 4 to obtain a mixture; continuously stir the mixture for 2 hours to allow hydrogen silicone oil, tetraethyl orthosilicate to fully contact with the diatomaceous earth, and then centrifuge to obtain modified diatomaceous earth.

[0029] Disperse the above mixture and the modified diatomaceous earth in 130 parts of acrylate polymer emulsion, heat to 70 - 90 °C, stir at a speed of 300 - 500 rpm for 5 min, add 10 parts of defoamer and 8 parts of silane coupling agent, and react for 3 min; cool to room temperature, stop stirring, and obtain the waterproof coating of this example.

[0030] Example 3 Take 90 parts of cement, 40 parts of silicon nitride, and 25 parts of talcum powder, mix them, and stir to form a mixture at a stirring speed of 150 rpm for 2 min; Perform the pretreatment operations of drying, grinding, and sieving 40 parts of diatomaceous earth to prepare diatomaceous earth powder; drop 10 parts of hydrogen silicone oil and 30 parts of tetraethyl orthosilicate into anhydrous ethanol respectively, and keep stirring; slowly add the pretreated diatomaceous earth powder into anhydrous ethanol, stir well, add nitric acid to adjust the pH to 4 to obtain a mixture; keep stirring the mixture for 2 h to allow the hydrogen silicone oil, tetraethyl orthosilicate, and diatomaceous earth to fully contact, and then centrifuge to obtain the modified diatomaceous earth.

[0031] Disperse the above mixture and the modified diatomaceous earth in 100 parts of acrylate polymer emulsion, heat to 70 - 90 °C, stir at a speed of 300 - 500 rpm for 5 min, add 5 parts of defoamer and 6 parts of silane coupling agent, and react for 3 min; cool to room temperature, stop stirring, and obtain the waterproof coating of this example.

[0032] Example 4 Take 95 parts of cement, 30 parts of silicon nitride, and 30 parts of talcum powder, mix them, and stir to form a mixture at a stirring speed of 150 rpm for 2 min; Perform the pretreatment operations of drying, grinding, and sieving 50 parts of diatomaceous earth to prepare diatomaceous earth powder; drop 10 parts of hydrogen silicone oil and 40 parts of tetraethyl orthosilicate into anhydrous ethanol respectively, and keep stirring; slowly add the pretreated diatomaceous earth powder into anhydrous ethanol, stir well, add nitric acid to adjust the pH to 4 to obtain a mixture; keep stirring the mixture for 2 h to allow the hydrogen silicone oil, tetraethyl orthosilicate, and diatomaceous earth to fully contact, and then centrifuge to obtain the modified diatomaceous earth.

[0033] Disperse the above mixture and the modified diatomaceous earth in 80 parts of acrylate polymer emulsion, heat to 70 - 90 °C, stir at a speed of 300 - 500 rpm for 5 min, add 5 parts of defoamer and 4 parts of silane coupling agent, and react for 3 min; cool to room temperature, stop stirring, and obtain the waterproof coating of this example.

[0034] Example 5 Take 110 parts of cement, 20 parts of silicon nitride, and 30 parts of talcum powder, mix them, and stir to form a mixture at a stirring speed of 150 rpm for 2 min; Perform pretreatment operations of drying, grinding, and sieving 20 parts of diatomaceous earth to obtain diatomaceous earth powder; separately drop 10 parts of hydrogen silicone oil and 50 parts of tetraethyl orthosilicate into anhydrous ethanol, and continuously stir; slowly add the pretreated diatomaceous earth powder into anhydrous ethanol, stir well, add nitric acid to adjust the pH to 4 to obtain a mixture; continuously stir the mixture for 2 h, so that the hydrogen silicone oil, tetraethyl orthosilicate and diatomaceous earth are in full contact, and then centrifuge to obtain modified diatomaceous earth.

[0035] Disperse the above mixture and modified diatomaceous earth in 60 parts of acrylate polymer emulsion, heat to 70 - 90 °C, stir at a stirring speed of 300 - 500 rpm for 5 min, add 10 parts of defoamer and 2 parts of silane coupling agent, and react for 3 min; cool to room temperature, stop stirring to obtain the waterproof coating of this example.

[0036] Comparative Example 1 Take 90 parts of cement, 40 parts of silicon nitride, and 25 parts of talcum powder, mix them and stir to form a mixture, with a stirring speed of 150 rpm and stir for 2 min; Disperse the above mixture and 40 parts of ordinary diatomaceous earth in 100 parts of acrylate polymer emulsion, heat to 70 - 90 °C, stir at a stirring speed of 300 - 500 rpm for 5 min, add 5 parts of defoamer and 6 parts of silane coupling agent, and react for 3 min; cool to room temperature, stop stirring to obtain the waterproof coating of this example.

[0037] Comparative Example 2 Take 95 parts of cement, 30 parts of silicon nitride, and 30 parts of talcum powder, mix them and stir to form a mixture, with a stirring speed of 150 rpm and stir for 2 min; Disperse the above mixture in 80 parts of acrylate polymer emulsion, heat to 70 - 90 °C, stir at a stirring speed of 300 - 500 rpm for 5 min, Drop 10 parts of hydrogen silicone oil and 50 parts of tetraethyl orthosilicate into the acrylate polymer emulsion respectively, continuously stir, stir at a stirring speed of 300 - 500 rpm for 5 min; add nitric acid to adjust the pH to 4, add 10 parts of defoamer and 2 parts of silane coupling agent, and react for 3 min; cool to room temperature, stop stirring to obtain the waterproof coating of this example.

[0038] Comparative Example 3 Take 110 parts of cement, 20 parts of silicon nitride, and 30 parts of talcum powder, mix them and stir to form a mixture, with a stirring speed of 150 rpm and stir for 2 min; Disperse the above mixture in 60 parts of acrylate polymer emulsion, heat it to 70 - 90 °C, stir at a speed of 300 - 500 rpm for 5 min, add 10 parts of defoamer and 2 parts of silane coupling agent, and react for 3 min; cool to room temperature, stop stirring, and obtain the waterproof coating of this example.

[0039] The composition of the waterproof coatings of Examples 1 - 5 and Comparative Examples 1 - 3 is shown in Table 1 below.

[0040] Test the alkali corrosion resistance of the waterproof coatings in Examples 1 - 5 and Comparative Examples 1 - 3 according to GB / T 9265 - 2009 "Determination of Alkali Resistance of Building Coating Films", test the water impermeability after temperature change cycle according to GB / T 16777 - 2008 "Test Methods for Building Waterproof Coatings", conduct hardness test according to GB / T 6739 - 2006 "Determination of Film Hardness by Pencil Method for Paints and Varnishes" and conduct scratch test with 450 N. The test results are shown in Table 2 below.

[0041] According to the data in Table 2, the waterproof coatings of Examples 1 - 5 have improved alkali resistance, waterproof performance and / or wear resistance compared with Comparative Examples 1 - 3. This is because in this solution, the modified diatomite enables the waterproof coating to better adapt to the deformation of the cement substrate, and is not easily caused by the slight displacement or expansion of the substrate. The waterproof layer ruptures, improving the adaptability of the waterproof coating to different substrates. In addition, the unique microporous structure of diatomite can form a tortuous channel in the coating, increasing the penetration resistance of the alkaline substances generated during the curing of the wall surface.

[0042] Based on the theory of synergistic modification, hydrogen silicone oil - tetraethyl orthosilicate has a filling effect on diatomite. The hydrolyzed nano - SiO2 particles fill the pore structure on the surface of the coating and participate in the hydration reaction, increasing the content of the gel phase, so that the surface of the coating is more dense, hindering the leaching channel of alkaline ions. Hydrogen silicone oil - tetraethyl orthosilicate can effectively penetrate into the geopolymer coating and chemically bond with the gel phase structure, improving the bonding ability of the coating.

[0043] In addition, when the modified waterproof coating penetrates into the wall voids and encounters the alkaline substances on the wall, tetraethyl orthosilicate in the modified waterproof coating is rapidly hydrolyzed under the catalysis of alkali to generate nano - sized silica particles. The - OH groups on the surface of these nano - sized silica particles react with the active Si - H bonds in the hydrogen silicone oil, so that the hydrophobic groups are connected to the surface of the nano - sized silica particles, protecting the wall from powdering and destroying the coating substrate structure. When the alkaline substances contact the coating, the nano - sized silica particles formed after the hydrolysis of tetraethyl orthosilicate in the pores of diatomite seal the pores of diatomite, further preventing the alkaline substances from destroying the coating.

[0044] In Comparative Example 1, based on the formulation of Example 3, only ordinary diatomaceous earth was added. Diatomaceous earth has high hardness and wear resistance, and when added to the waterproof coating, it can enhance the mechanical strength of the coating and improve the ability of the coating to resist external force impact and friction. However, alkaline substances can still penetrate into the pores in the diatomaceous earth and continue to damage the coating.

[0045] In Comparative Example 2, based on the formulation of Example 4, hydrogen silicone oil and tetraethyl orthosilicate were added. Since there is no diatomaceous earth as the basis for the water-blocking structure in the coating, the nano-scale silica produced by the hydrolysis of tetraethyl orthosilicate can make the coating more dense and has a certain ability to prevent the penetration of alkaline substances.

[0046] In Comparative Example 3, based on the formulation of Example 5, modified diatomaceous earth was not added. The waterproof coating formed by the formulation of Comparative Example 3 has poor hardness, alkali resistance and waterproof performance.

[0047] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0048] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A modified waterproof coating, characterized in that, The waterproof coating comprises the following components in parts by weight: 60 - 110 parts of cement; 60 - 160 parts of acrylate polymer emulsion; 20 - 50 parts of modified diatomaceous earth; 20 - 50 parts of silicon nitride; 20 - 30 parts of talcum powder; 5 - 15 parts of defoamer; 2 - 10 parts of silane coupling agent.

2. The modified waterproof coating according to claim 1, wherein The preparation method of the modified diatomaceous earth is as follows: Perform pretreatment operations of drying, grinding, and sieving on diatomaceous earth powder to obtain diatomaceous earth powder; Drop hydrogen silicone oil and tetraethyl orthosilicate into absolute ethanol respectively, and continuously stir; Add the pretreated diatomaceous earth powder into absolute ethanol, stir well, add nitric acid to adjust the pH to 4 to obtain a mixture; Continuously stir the mixture for 2 h to allow hydrogen silicone oil, tetraethyl orthosilicate to fully contact with diatomaceous earth, and then centrifuge to obtain modified diatomaceous earth.

3. The modified waterproof coating according to claim 2, characterized in that, The mass ratio of hydrogen silicone oil to tetraethyl orthosilicate is 2 - 5:

1.

4. The modified waterproof coating according to claim 1, characterized in that, The acrylate polymer emulsion is made from ethylene glycol dimethacrylate, dipentaerythritol hexaacrylate, and toluene diisocyanate as raw materials.

5. The modified waterproof coating according to claim 1, characterized in that, The cement is obtained by mixing ordinary Portland cement PO32.5 and fly ash Portland cement PF42.5 in a mass ratio of 1:2 - 3.

6. The modified waterproof coating according to claim 1, wherein, The silane coupling agent is aminopropyltriethoxysilane or γ - glycidoxypropyltrimethoxysilane.

7. The modified waterproof coating according to claim 1, wherein, The defoamer is emulsified methyl silicone oil.

8. A method for preparing the modified waterproof coating according to any one of claims 1-7, characterized in that, It includes the following steps: After mixing cement, silicon nitride, and talcum powder, stir to form a mixture at a stirring speed of 150 rpm for 2 min; Prepare modified diatomaceous earth; Disperse the mixture and modified diatomaceous earth in acrylate polymer emulsion, heat to 70 - 90 °C, stir at a stirring speed of 300 - 500 rpm for 5 min, add defoamer and silane coupling agent, and react for 3 min; 4) Cool to room temperature, stop stirring, and obtain the modified waterproof coating.

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