Environment-friendly and water-resistant inorganic coating and preparation method thereof

Abstract

The application discloses an environment-friendly and water-resistant inorganic coating and a preparation method thereof, and belongs to the technical field of materials. The environment-friendly and water-resistant inorganic coating comprises the following components in parts by weight: 15-25 parts of silicate, 25-35 parts of silica sol, 25-35 parts of pigment and filler, 0.8-1.2 parts of thickening agent, 0.8-1.2 parts of defoaming agent, 0.8-1.2 parts of dispersing agent, 2-3 parts of water-resistant agent, 4-6 parts of modifier, 3-5 parts of organic emulsion and 35-50 parts of deionized water. The silicate is composed of potassium silicate without deionized water and deionized water; and the water-resistant agent is prepared from hexadecyl trimethoxysilane modified tetraethyl orthosilicate and isopropyl titanate. The application has wide raw material sources and simple process, and the prepared inorganic coating has good environment-friendly and water-resistant performances, and has remarkable economic and social benefits.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of materials, and particularly relates to an environment-friendly and water-resistant inorganic coating and a preparation method thereof. BACKGROUND

[0002] Inorganic coating is a type of coating prepared mainly from inorganic film-forming substances. Compared with organic coating, inorganic coating has the advantages of low VOC content, fire resistance, and anti-aging. At present, inorganic coating mainly refers to silicate inorganic coating. Potassium silicate is the first choice for inorganic coating because it has better film-forming than sodium silicate and is cheaper than lithium silicate. Due to the hydrophilicity of inorganic coating, inorganic coating generally has poor water resistance. Most water-resistant agents fail to maintain stability during long-term use, resulting in failure of inorganic coating.

[0003] Nano-silicon dioxide is an important coating additive material, which has the characteristics of high strength, high toughness, and good stability at high temperature. Nano-silicon dioxide also has strong ultraviolet absorption function and infrared reflection function, thereby improving the anti-aging function of exterior wall coating.

[0004] Nano-titanium dioxide is an important whitening material, which has the advantages of good stability, corrosion resistance, and self-cleaning. In coating, nano-titanium dioxide not only serves as a pigment, but also is an important filler, which can enhance the mechanical strength and adhesion of the paint film. When the crystal form of nano-titanium dioxide is anatase, it has stable properties and high photocatalytic activity, and can decompose formaldehyde.

[0005] Silane coupling agent is a material containing easily hydrolyzable silanol groups on one end. Silanol groups have reactivity with inorganic substances. On the other side, silane coupling agent contains organic functional groups, which have good compatibility with organic substances. Silane coupling agent itself is a hydrophobic material, which is easily soluble in ethanol and insoluble in cold water. With the increase of water temperature, silane coupling agent gradually starts to hydrolyze. pH also plays an important role in the hydrolysis of silane coupling agent. Silane coupling agent shows good hydrolysis in both acidic and alkaline conditions.

[0006] The water-resistant agent synthesized by the sol-gel method has good hydrophobicity, and has good compatibility with inorganic coating. The modification of titanium dioxide with other materials can improve the spectral absorption range and photocatalytic activity. Silicon dioxide has less ultraviolet absorption, which can improve the mineralization ability of organic matter. As a carrier of titanium dioxide, silicon dioxide can not only improve the specific surface area and adsorption performance of titanium dioxide, but also inhibit the recombination of photo-generated carriers in titanium dioxide, improve the utilization efficiency of photo-generated carriers, and thus improve the photocatalytic performance of the material and the degradation of organic matter. When applied to inorganic coating, it makes the inorganic coating more environmentally friendly. SUMMARY

[0007] The present application aims to provide an environment-friendly, water-resistant inorganic coating and a preparation method thereof, and solve the problems of complex process, high manufacturing cost, use of toxic organic solvents in the production process, unavoidable formaldehyde emission in the coating, and low self-cleaning function of the coating in the prior art.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] An environment-friendly, water-resistant inorganic coating comprises the following components in parts by weight: 15-25 parts of silicate, 25-35 parts of silica sol, 25-35 parts of pigment and filler, 0.8-1.2 parts of thickening agent, 0.8-1.2 parts of defoaming agent, 0.8-1.2 parts of dispersing agent, 2-3 parts of water-resistant agent, 4-6 parts of modifier, 3-5 parts of organic emulsion, and 35-50 parts of deionized water.

[0010] Optionally, the silicate is selected from at least one of potassium silicate, sodium silicate, and lithium silicate.

[0011] Preferably, the silicate is potassium silicate.

[0012] In the present application, the silicate and the silica sol jointly serve as inorganic binders. The potassium silicate deionized aqueous solution is prepared by dissolving the potassium silicate solid without deionized water in deionized water, and 30% solid content silica sol is added to the potassium silicate deionized aqueous solution to accurately prepare potassium silicate solutions with different modulus.

[0013] Optionally, the pigment and filler are selected from at least one of titanium dioxide, heavy calcium carbonate, wollastonite, calcined kaolin, mica powder, and sepiolite.

[0014] Optionally, the thickening agent is selected from at least one of hydroxypropyl methylcellulose, hydroxyethyl cellulose, and polyacrylate.

[0015] Preferably, the thickening agent is hydroxyethyl cellulose.

[0016] Optionally, the defoaming agent is selected from at least one of tributyl phosphate, silicone defoaming agent, and aluminum hydroxide.

[0017] Preferably, the defoaming agent is tributyl phosphate.

[0018] Optionally, the dispersing agent is selected from at least one of sodium hexametaphosphate, sodium succinate, and polyacrylamide.

[0019] Preferably, the dispersing agent is sodium hexametaphosphate.

[0020] Optionally, the modifier is at least one of potassium methyl silicate, gamma-aminopropyl triethoxysilane, and gamma-reduced glycerol ether oxypropyl trimethoxysilane.

[0021] Preferably, the modifier is potassium methyl silicate.

[0022] Optionally, the organic emulsion is selected from at least one of styrene-acrylic, silicone-acrylic and pure-acrylic.

[0023] Preferably, the organic emulsion is selected from styrene-acrylic.

[0024] Optionally, the water-resistant agent is a hydrophobic composite particle, which is prepared by the following steps:

[0025] The tetraethyl orthosilicate raw material and isopropyl titanate raw material are dissolved in 50 mL of anhydrous ethanol, heated at 60°C and stirred for 30 min, then 50 mL of deionized water is added dropwise, and hexadecyl trimethoxysilane is added as a silane coupling agent, the pH is adjusted to 3 with hydrochloric acid, and the solution temperature is raised to 107°C, the water is refluxed and cooled, the heating reflux time is 5 h, after stirring, gelation occurs, and the solution is cooled at room temperature, a layered liquid is obtained, the supernatant is removed, and a lower block solid is obtained, which is placed in an oven at 120°C for drying for 12 h, and washed with anhydrous ethanol, and transferred to an oven at 65°C for drying for 12 h, and the obtained block object is ground to obtain a hydrophobic composite particle.

[0026] The preparation method of the inorganic coating described above comprises the following steps:

[0027] (1) Dissolve the potassium silicate solid without deionized water in deionized water and continuously stir to obtain a potassium silicate solution, add a silica sol to obtain a potassium silicate solution with different moduli, continue to add an organic emulsion and a modifier and stir for 30 min to obtain a modified potassium silicate solution with different moduli, i.e. component A.

[0028] (2) Add the pigments and fillers, thickening agents, dispersants, water-resistant agents and deionized water into a dispersion cylinder and disperse to obtain a mixed solution, i.e. component B.

[0029] (3) Add component A to component B, and add a defoaming agent at the same time, and disperse at high speed to obtain the inorganic coating.

[0030] Preferably, the stirring speed in step (1) is 150 r / min, and the stirring time is 10 min.

[0031] Preferably, the dispersion speed in step (2) is 500 r / min, and the dispersion time is 5 min.

[0032] Preferably, the dispersion speed in step (2) is 100 r / min, and the dispersion time is 25 min.

[0033] Compared with the prior art, the present application has the following advantages:

[0034] (1) The titanium dioxide is modified by compounding with the silicon dioxide to improve the light spectrum absorption range and the photocatalytic activity of the titanium dioxide.

[0035] (2) The water-resistant agent prepared by the sol-gel method is easy to migrate to the surface of the coating in the water-based paint due to the hydrophobic modification, thereby increasing the proportion of the hydrophobic agent in contact with light, and improving the photocatalytic effect of the titanium dioxide.

[0036] (3) The hydrophobic agent prepared by the present application has good stability, and after water immersion for 300h (GB / T 1733-93), the inorganic coating does not appear the phenomena of blistering, peeling and cracking.

[0037] (4) Different modulus of potassium silicate is prepared by using anhydrous potassium silicate, and the modulus of the potassium silicate solution is accurately controlled to make the water resistance of the inorganic coating reach the best without cracking.

[0038] (5) The environmental protection of the hydrophobic agent prepared by the present application is that the formaldehyde content test (GB18580-2017) is less than 0.05 mg / m 3 , reaching the E0 level. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The Fourier infrared spectrum of the water-resistant agent prepared in the present application is shown in the figure;

[0040] Figure 2 The XRD diagram of the water-resistant agent prepared in the present application is shown in the figure;

[0041] Figure 3 The scanning electron microscope diagram of the water-resistant agent prepared in the present application is shown in the figure. DETAILED DESCRIPTION

[0042] In order to make the content of the present application more convenient to understand, the technical solutions of the present application will be further described in combination with specific embodiments, but the present application is not limited thereto.

[0043] Example 1

[0044] (1) Preparation of potassium silicate with modulus of 5: 3 g of potassium silicate solid without deionized water was dissolved in 7 g of deionized water, and continuously stirred to obtain a potassium silicate solution with a solid content of 30%. Then, 15.6 g of silica sol with a solid content of 30% was added to obtain a potassium silicate solution with a modulus of 5. Then, 2 g of benzene propyl and 1 g of methyl potassium silicate solution were continuously added and stirred for 30 min to obtain a modified potassium silicate solution with a modulus of 5.

[0045] (2) Preparation of water-resistant agent: 10 g of tetraethyl orthosilicate raw material and 5 g of isopropyl titanate raw material were dissolved in 50 mL of anhydrous ethanol, heated at 60°C and stirred for 30 min. Then, 50 mL of deionized water was added dropwise, and 1 g of silane coupling agent hexadecyl trimethoxysilane was added. The pH was adjusted to 3 with hydrochloric acid, and the solution temperature was increased to 107°C. The water was refluxed and cooled. The heating reflux time was 5 h. After stirring, a gel phenomenon appeared. The solution was cooled at room temperature. The supernatant was removed, and the lower block solid was obtained. It was dried in an oven at 120°C for 12 h and washed with anhydrous ethanol. It was transferred to an oven at 65°C for drying for 12 h. The obtained block object was ground to obtain hydrophobic composite particles, i.e. water-resistant agent.

[0046] (3) Preparation of environment-friendly and water-resistant inorganic coating: 12 parts of heavy calcium carbonate, 2 parts of titanium dioxide, 4 parts of mica powder, 6 parts of calcined kaolin, 4 parts of wollastonite, 1 part of hydroxyethyl cellulose, 1 part of sodium hexametaphosphate, 2 parts of methyl potassium silicate, 4 parts of water-resistant agent, and 40 parts of deionized water were added to a dispersion cylinder. The solution was dispersed at a speed of 500 r / min for 5 min. Then, 57 parts of the prepared modified potassium silicate solution with a modulus of 5 was added, and 1 part of phosphorus tributyl was added. The solution was dispersed at a speed of 1000 r / min for 30 min to obtain the environment-friendly and water-resistant inorganic coating.

[0047] Comparative Example 1 (without adding water-resistant agent)

[0048] (1) Preparation of potassium silicate with modulus of 5: 3 g of potassium silicate solid without deionized water was dissolved in 7 g of deionized water, and continuously stirred to obtain a potassium silicate solution with a solid content of 30%. Then, 15.6 g of silica sol with a solid content of 30% was added to obtain a potassium silicate solution with a modulus of 5. Then, 2 g of benzene propyl and 1 g of methyl potassium silicate solution were continuously added and stirred for 30 min to obtain a modified potassium silicate solution with a modulus of 5.

[0049] (2) Preparation of the environment-friendly and water-resistant inorganic coating: 12 parts of heavy calcium carbonate, 2 parts of titanium dioxide, 4 parts of mica powder, 6 parts of calcined kaolin, 4 parts of wollastonite, 1 part of hydroxyethyl cellulose, 1 part of sodium hexametaphosphate, 2 parts of potassium methyl silicate, 40 parts of deionized water, and 4 parts of the water-resistant agent were added into a dispersing cylinder, and dispersed at a speed of 500 r / min for 5 min. Then, 57 parts of the prepared modified potassium silicate solution with a modulus of 5 was added, and 1 part of tributyl phosphate was also added. The mixture was dispersed at a speed of 1000 r / min for 30 min, and finally the environment-friendly and water-resistant inorganic coating was obtained.

[0050] Comparative Example 2 (potassium silicate solution with a modulus of 4)

[0051] (1) Preparation of potassium silicate with a modulus of 5: 3 g of potassium silicate solid without deionized water was dissolved in 7 g of deionized water, and stirred continuously to obtain a potassium silicate solution with a solid content of 30%. Then, 117 g of silica sol with a solid content of 30% was added to obtain a potassium silicate solution with a modulus of 5. Then, 2 g of benzene propyl and 1 g of potassium methyl silicate solution were added and stirred for 30 min to obtain a modified potassium silicate solution with a modulus of 5.

[0052] (2) Preparation of the water-resistant agent: 10 g of tetraethyl orthosilicate raw material and 5 g of isopropyl titanate raw material were dissolved in 50 mL of anhydrous ethanol, heated at 60°C and stirred for 30 min. Then, 50 mL of deionized water was added dropwise, and 1 g of silane coupling agent hexadecyl trimethoxysilane was added. The pH was adjusted to 3 with hydrochloric acid, and the solution temperature was increased to 107°C. The water was refluxed and cooled, and the heating reflux time was 5 h. After stirring, gelation occurred, and the solution was cooled at room temperature. The supernatant was removed, and the lower layer of solid was obtained. The solid was dried in an oven at 120°C for 12 h, washed with anhydrous ethanol, transferred to an oven at 65°C for drying for 12 h, and ground to obtain hydrophobic composite particles, i.e., the water-resistant agent.

[0053] (3) Preparation of the environment-friendly and water-resistant inorganic coating: 12 parts of heavy calcium carbonate, 2 parts of titanium dioxide, 4 parts of mica powder, 6 parts of calcined kaolin, 4 parts of wollastonite, 1 part of hydroxyethyl cellulose, 1 part of sodium hexametaphosphate, 2 parts of potassium methyl silicate, 40 parts of deionized water, and 4 parts of the water-resistant agent were added into a dispersing cylinder, and dispersed at a speed of 500 r / min for 5 min. Then, 57 parts of the prepared modified potassium silicate solution with a modulus of 5 was added, and 1 part of tributyl phosphate was also added. The mixture was dispersed at a speed of 1000 r / min for 30 min, and finally the environment-friendly and water-resistant inorganic coating was obtained.

[0054] Comparative Example 3 (potassium silicate solution with a modulus of 6)

[0055] (1) Preparation of potassium silicate with modulus of 5: 3 g of potassium silicate solid without deionized water was dissolved in 7 g of deionized water, and stirring was continuously carried out to obtain a potassium silicate solution with a solid content of 30%, 19.5 g of silica sol with a solid content of 30% was added to obtain a potassium silicate solution with a modulus of 5, 2 g of phenylpropyl and 1 g of methyl potassium silicate solution were continuously added and stirred for 30 min to obtain a modified potassium silicate solution with a modulus of 5.

[0056] (2) Preparation of water-resistant agent: 10 g of tetraethyl orthosilicate raw material and 5 g of isopropyl titanate raw material were dissolved in 50 mL of anhydrous ethanol, heated at 60°C and stirred for 30 min, 50 mL of deionized water was added dropwise, 1 g of silane coupling agent hexadecyltrimethoxysilane was added, the pH was adjusted to 3 with hydrochloric acid, and the solution temperature was increased to 107°C, the water was refluxed and cooled, the heating reflux time was 5 h, after stirring, gelation occurred, and the solution was cooled at room temperature to obtain a layered liquid, the supernatant was removed, and a block-shaped solid was obtained, which was dried in an oven at 120°C for 12 h, washed with anhydrous ethanol, and transferred to an oven at 65°C for drying for 12 h, and the obtained block-shaped object was ground to obtain hydrophobic composite particles, i.e. water-resistant agent.

[0057] (3) Preparation of environment-friendly and water-resistant inorganic paint: 12 parts of heavy calcium carbonate, 2 parts of titanium dioxide, 4 parts of mica powder, 6 parts of calcined kaolin, 4 parts of wollastonite, 1 part of hydroxyethyl cellulose, 1 part of sodium hexametaphosphate, 2 parts of methyl potassium silicate, 4 parts of water-resistant agent, and 40 parts of deionized water were added to a dispersion cylinder, and dispersed at a speed of 500 r / min for 5 min, 57 parts of the prepared modified potassium silicate solution with a modulus of 5 was added, and 1 part of tributyl phosphate was added at the same time, and dispersed at a speed of 1000 r / min for 30 min, to obtain the environment-friendly and water-resistant inorganic paint.

[0058] The samples obtained in the examples and comparative examples were subjected to performance tests, and the results are shown in Table 1.

[0059]

[0060] Table 1 shows that the construction of the examples and comparative examples meets the requirements, and the brushing is unobstructed. By adding water-resistant agent (Example 1) and not adding water-resistant agent (Comparative Example 1), the inorganic paint with water-resistant agent does not bubble, fall off or crack after water resistance test; the inorganic paint without water-resistant agent has slight falling off and powdering after water resistance test. At the same time, under different moduli, the water resistance and cracking resistance of the paint also show different situations, when the modulus of the inorganic paint is 5, the inorganic paint does not bubble, fall off or crack; when the modulus of the inorganic paint is 4, the inorganic paint has slight falling off; and when the modulus of the inorganic paint is 6, the inorganic paint has slight cracking.

[0061] Formaldehyde content in coatings tested according to GB18580-2017; the formaldehyde concentration in both the example and comparative examples was below 0.05 mg / m³. 3 It achieves the E0 standard. Furthermore, the addition of a hydrophobic agent slightly reduces the formaldehyde content of the inorganic coating, making it more environmentally friendly.

[0062] Fourier transform infrared spectroscopy was performed on the inorganic superhydrophobic composite particles, and the test results are as follows: Figure 1 As shown, by Figure 1 It can be seen that the infrared spectrum is at 2927 cm⁻¹ -1 A -CH3 stretching vibration peak is present at 2856 cm⁻¹. -1 A -CH2 stretching vibration peak is present at 1467 cm⁻¹. -1 A -CH2 bending vibration peak is present at 1060 cm⁻¹. -1 There is an asymmetric stretching vibration absorption peak of Si-O-Si at 800 cm⁻¹. -1 There is a Si-O-Si symmetric stretching vibration absorption peak at 449 cm⁻¹. -1 The presence of a Si-O-Si bending vibration absorption peak at 946 cm⁻¹ indicates that the silane coupling agent hexadecyltrimethoxysilane was successfully grafted onto the silica surface; the water-resistant agent showed an absorption peak at 946 cm⁻¹. -1 The presence of Ti-O-Si vibrational bands indicates that silicon dioxide was successfully grafted onto the surface of titanium dioxide.

[0063] The water-resistant agent was tested using an X-ray diffractometer, and the test results are as follows: Figure 2 As shown, distinct characteristic diffraction peaks appear at 25.51°, 37.95°, 48.21°, 54.05°, and 62.84°, respectively. Referring to PDF card (73-1764), these peaks correspond to the diffraction of the (101), (004), (200), (105), and (204) crystal planes in the anatase structure, indicating that the TiO2 crystal form generated from the isopropyl titanate raw material is anatase. The characteristic diffraction peak of amorphous SiO2 is at 21.92°. Since the characteristic diffraction peak of TiO2 is stronger than that of SiO2, the characteristic diffraction peak of amorphous SiO2 is not obvious at 21.92°, but it can still be observed from... Figure 2 Observed at the blue arrow in the middle.

[0064] The water-resistant agent was subjected to scanning electron microscopy (SEM) testing, and the test results are as follows: Figure 3 As shown, Figure 3 The red arrows point to the prepared hydrophobic microspheres. The size is approximately 1.1 μm, while the other microspheres are 80-900 nanometers in size, which constitutes a micro / nano structure and improves the water resistance of the inorganic coating.

[0065] The above merely illustrates the preferred embodiments and the comparative examples of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent processing scope of the present application.

Claims

1. An environmentally friendly, water-resistant inorganic coating, characterized by: Components comprising the following parts by weight: silicate 15-25 parts, silica sol 25-35 parts, pigment and filler 25-35 parts, thickening agent 0.8-1.2 parts, defoaming agent 0.8-1.2 parts, dispersing agent 0.8-1.2 parts, water resistance agent 2-3 parts, modifier 4-6 parts, organic emulsion 3-5 parts and deionized water 35-50 parts; The silicate is potassium silicate; The water resistance agent is an inorganic hydrophobic composite particle, and its preparation method comprises the following steps: (1) 10 g of tetraethyl orthosilicate and 5 g of isopropyl titanate are dissolved in 50 mL of anhydrous ethanol, heated at 60°C and stirred for 30 min, then 50 mL of deionized water is added dropwise, and 1 g of silane coupling agent hexadecyl trimethoxysilane is added, the pH is adjusted to 3 with hydrochloric acid, and the solution is heated to 107°C, refluxed for 5 h, naturally cooled, and separated into layers to obtain a lower layer of blocky solid; (2) The lower layer of blocky solid is dried at 120°C for 12 h, washed with anhydrous ethanol, dried at 65°C for 12 h, ground, and the inorganic hydrophobic composite particle is obtained; The modifier is at least one of potassium methyl silicate, γ-aminopropyl triethoxysilane and γ-glycidyl ether propyl trimethoxysilane.

2. The inorganic coating of claim 1, wherein: The pigment and filler is at least one of titanium dioxide, heavy calcium carbonate, wollastonite, calcined kaolin, mica powder and sepiolite.

3. The inorganic coating of claim 1, wherein: The thickening agent is at least one of hydroxypropyl methylcellulose, hydroxyethyl cellulose and polyacrylate.

4. The inorganic coating of claim 1, wherein: The defoaming agent is at least one of tributyl phosphate, silicone defoaming agent and aluminum hydroxide.

5. The inorganic coating of claim 1, wherein: The dispersing agent is at least one of sodium hexametaphosphate, sodium succinate and polyacrylamide.

6. The inorganic coating of claim 1, wherein: The organic emulsion is at least one of styrene-acrylate emulsion, silicone-acrylate emulsion and pure acrylic emulsion.

7. A process for the preparation of the inorganic coating according to any one of claims 1 to 6, characterized in that: Comprising the following steps: (1) Dissolve the silicate in deionized water, stir until uniform, add the silica sol, stir until uniform, then add the organic emulsion and the modifier, stir until uniform, and obtain component A; (2) Mix the pigment and filler, the thickening agent, the dispersing agent, the water resistance agent and the deionized water uniformly to obtain component B; (3) Add component A to component B, add the defoaming agent at the same time, and disperse at high speed to obtain the inorganic coating.

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