An acid- and alkali-resistant environmentally friendly inorganic coating and its preparation method

Abstract

The present invention discloses an acid and alkali resistant environmentally friendly inorganic coating and a preparation method thereof, which are made from the following raw materials in parts by weight: 20-28 parts of silicate, 10-20 parts of silica sol, 30-50 parts of pigment extender, 0.5-1 part of thickener, 0.5-1 part of alkali resistant dispersant, 20-45 parts of deionized water, and 0.5-1 part of water swelling agent. The silicate is at least one of sodium silicate, potassium silicate, calcium silicate and aluminum silicate. The alkaline silica sol is nano-scale silica sol with an average particle size not greater than 20 nm, a mass fraction of sodium oxide ≤ 0.25%, a viscosity ≤ 15 mPa·s, and an average particle size of 8-20 nm, having excellent properties such as low metal content, high uniform distribution and good stability. The pigment extender is at least one of quartz powder, talc powder, calcium carbonate, titanium dioxide and barium sulfate with a mesh number of 500-1500. The present invention overcomes the deficiencies of the prior art, can further improve the overall stability and fluidity of the coating, and has high social use value and application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of inorganic coatings, and particularly to an acid and alkali resistant environmentally friendly inorganic coating and a preparation method thereof. Background Art

[0002] After the promulgation of international environmental protection laws, the coating industry, as a major pollution source, has been developing towards low-pollution and environmentally friendly coatings, and countries around the world have imposed restrictions on the content of volatile organic compounds (VOCs) in coatings. With the continuous development of the coating industry, there are more and more low-pollution and environmentally friendly coating products, which can be divided into two categories: organic coatings and inorganic coatings. However, most of the existing organic coatings contain polymers such as acrylate or PVC. The coatings have slight corrosiveness to buildings, poor dust absorption and weather resistance, and still cause certain environmental pollution; while the existing inorganic coatings are environmentally friendly, but there are still defects: poor adhesion, easy cracking during the film-forming process of brushing, poor acid and alkali water resistance, and poor flame retardant effect.

[0003] Especially in the field of construction engineering, coatings not only have the effect of beautifying the appearance of buildings, but also play a crucial role in the protection of buildings. Among them, coatings for building exterior walls need to be exposed to the external environment for a long time and are eroded by air, ultraviolet rays, rainwater and chemical substances. Therefore, they not only need to meet the requirements for basic properties such as mechanical strength, but also need to have excellent acid and alkali corrosion resistance. At the same time, in order to extend the protection effect and service life, good adhesion and anti-cracking properties are also essential. Currently, commonly used exterior wall coatings often mildew or even fall off after being painted for a period of time, seriously affecting the aesthetics of the wall surface; in addition, the high temperature resistance of the coatings also needs to be improved to ensure the long-term use of the coatings.

[0004] At present, there are also some applications and researches on waterborne inorganic coatings in the prior art. For example: Chinese Patent CN109777162A, a waterborne interior wall coating with an inorganic material as the film-forming substance and a preparation method thereof, discloses water, silica sol, potassium silicate and diatomite, wherein the diatomite is diatomite loaded with nano-titanium dioxide, and various functional additives are also included. The components are complex and numerous. And from the embodiment mode, it can be seen that each component is its key condition, and the lack or replacement of any component will have an adverse impact on the coating performance, and the performance in aspects such as water resistance, abrasion resistance and hardness is not objectively and comprehensively described.

[0005] In CN201510766239.4, an environmentally friendly waterborne PVA-modified interior wall functional coating uses a modified PVA emulsion as the main raw material and is combined with a wax emulsion with hydrophobicity to prevent the penetration of water vapor, achieving the effects of water resistance and scrub resistance.

[0006] Among the existing water-based inorganic coatings, in order to solve the technical problems such as waterproofing, surface hardness, and abrasion resistance of water-based inorganic coatings, the technical means adopted are also different. How to further improve the waterproofing, bonding force with the front surface, and scrub resistance of water-based inorganic coatings is the technical problem that this invention focuses on solving. Summary of the Invention

[0007] In order to solve the problems mentioned in the above background technology, this invention provides an acid and alkali resistant environmentally friendly inorganic coating and its preparation method.

[0008] In order to achieve the above purpose, this invention adopts the following technical solutions:

[0009] An acid and alkali resistant environmentally friendly inorganic coating is made from the following raw materials in parts by weight: 20 - 28 parts of silicate, 10 - 20 parts of silica sol, 30 - 50 parts of pigment and filler, 0.5 - 1 part of thickener, 0.5 - 1 part of alkali resistant dispersant, 20 - 45 parts of deionized water, and 0.5 - 1 part of water enhancer.

[0010] Preferably, the silicate is at least one of sodium silicate, potassium silicate, calcium silicate, and aluminum silicate.

[0011] Preferably, the silica sol is alkaline silica sol, with a silica content of 25 - 35%, pH of 8.0 - 9.5; the alkaline silica sol is nano-level silica sol, with an average particle size not greater than 20nm, a sodium oxide mass fraction ≤ 0.25%, a viscosity ≤ 15mpa.s, an average particle size of 8 - 20nm, and has excellent properties such as low metal content, high uniform distribution, and good stability.

[0012] Preferably, the pigment and filler is at least one of quartz powder, talc powder, calcium carbonate, titanium dioxide, and barium sulfate with a mesh number of 500 - 1500.

[0013] Preferably, the thickener is water-based polyamide wax, including the following steps:

[0014] S1: Add heat stabilizer, water-based polyamide wax slurry, and organic solvent into the reaction kettle, and heat up to 125 - 130°C until the heat stabilizer and water-based polyamide wax slurry are completely dissolved in the corresponding organic solvent; the effective active substance content of the water-based polyamide wax slurry is 20%, and the acid value is 12.0 - 13.0mgKOH / g;

[0015] S2: Then slowly add at least one organic amine, start cooling after the feeding is completed, add a surfactant when the temperature drops to 75 - 85°C, and then keep stirring and dispersing at this temperature to obtain the first reaction material;

[0016] S3: Heat the deionized water to 85 - 90 °C, then slowly add the first reaction material dispersed in S2 into the heated deionized water, control the stirring speed at 800 - 1200 rmp, and stop stirring when the temperature of the mixed solution drops below 60 °C;

[0017] S4: Finally, cool it to room temperature to obtain the aqueous polyamide wax thickener.

[0018] In the preparation process of the thickener of the present invention, materials containing amide group components are selected, which are more conducive to the interaction with the aqueous polyamide wax slurry and increase the compatibility. Second, considering from the crystallization performance, if the polyamide wax has a low acid value, a regular molecular chain structure, and intermolecular hydrogen bonds of amide bonds, its crystallization ability is strong, and it is very suitable as a crystal nucleus to induce the regular arrangement of the molecular chains of the aqueous polyamide wax and improve the crystallization ability of the aqueous polyamide wax.

[0019] Due to the introduction of heat-stable additive components in the pulping process, compared with the existing aqueous polyamide wax slurries on the market, the aqueous polyamide wax slurry prepared by the process of the present invention is characterized by excellent heat storage performance for aqueous inorganic coatings. After heat storage, its anti-settling and anti-sagging properties are hardly affected. For ordinary aqueous coatings with aqueous polyamide wax, their anti-settling and anti-sagging properties are greatly reduced after heat storage, bringing great risks to the storage of aqueous coatings in high-temperature environments.

[0020] Preferably, the heat-stable additive is a polyamide resin obtained by the reaction of a monocarboxylic acid and a diamine; the monocarboxylic acid is at least one of n-octanoic acid, n-nonanoic acid, n-decanoic acid, lauric acid, and 12-hydroxy stearic acid; the diamine is at least one of 4,4'-diaminodicyclohexylmethane, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, and dimer diamine.

[0021] Preferably, the organic solvent is at least one of propylene glycol n-propyl ether and propylene glycol monobutyl ether;

[0022] The organic amine is at least one of amine octane, dodecylamine, octadecylamine, and N-diethylethanolamine.

[0023] Preferably, the surfactant is at least one of fatty alcohol polyoxyethylene ether, sodium lauryl ether sulfate, polyoxyethylated nonylphenol ether, and alkylaryl polyoxyethylene ether.

[0024] Preferably, the alkali-resistant dispersant is at least one of sodium lignin sulfonate and maleic acid-acrylic acid copolymer;

[0025] The water-retaining agent is sodium methylsilanolate.

[0026] A preparation method of an acid- and alkali-resistant environmentally friendly inorganic coating further includes the following steps:

[0027] S1: Grind the pigment extender and silicate to a fineness of less than 10 μm according to the raw materials in parts by weight, and then mix them to obtain a mixed material.

[0028] S2: Add the mixed material obtained in step S1 to silica sol, and add deionized water and stir to obtain a slurry.

[0029] S3: Add a thickener, an alkali-resistant dispersant and a water-retaining agent to the slurry obtained in step S2 and stir evenly to obtain an acid and alkali resistant environmentally friendly inorganic coating.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. By adding nano-scale alkaline silica sol with an average particle size not greater than 20 nm, the present invention has high surface activity, which is beneficial to improving the compactness of the structure after gelling, thereby enhancing the coating strength of the inorganic coating after curing; the pH value of the nano-alkaline silica sol is 8.0-9.5, which is beneficial to ensuring the stable state of the sol, reducing particle aggregation and sedimentation, and maintaining the particle size of the alkaline silica sol, thereby enhancing the coating strength.

[0032] 2. Since an aqueous polyamide wax thickener is added during the preparation process of the coating, when the temperature rises, due to the low acid value, regular molecular chain structure and intermolecular hydrogen bonds of amide bonds of the selected polyamide wax, its crystallization ability is strong, and the crystal structure of the material is not easily damaged. The hydrogen bonds in the system are not easily damaged, thus avoiding serious stratification and sedimentation of the aqueous coating, and further enhancing the overall stability and fluidity of the coating, having high social use value and application prospects. Specific Embodiments

[0033] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0034] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market. The aqueous polyamide wax slurry is purchased from Zhejiang Fenghong New Materials Co., Ltd., and the model is PA-600;

[0035] The alkaline silica sol is nano-scale silica sol purchased from Shandong Kehan Silicon Source New Materials Co., Ltd., and the product model is KHZCM-30 (Fe <20 ppm, Al <20 ppm).

[0036] Preparation Example 1

[0037] The thickener is water-based polyamide wax, and the method comprises the following steps:

[0038] S1: Add 100 g of heat stabilizer, 400 g of water-based polyamide wax slurry and 250 g of propylene glycol monobutyl ether into a reaction kettle, and heat up to 125 °C until the heat stabilizer and the water-based polyamide wax slurry are completely dissolved in the corresponding propylene glycol monobutyl ether;

[0039] S2: Then slowly add 30 g of amine octane and 25 g of dodecylamine. After the feeding is completed, start to cool down. When the temperature drops to 75 °C, add 80 g of fatty alcohol polyoxyethylene ether, and then keep stirring and dispersing at this temperature to obtain the first reaction material;

[0040] S3: Heat deionized water to 85 °C, and then slowly add the first reaction material dispersed in S2 into 1000 ml of deionized water after heating. Control the stirring speed at 800 rmp, and stop stirring when the temperature of the mixed solution drops below 60 °C;

[0041] S4: Finally, cool to room temperature to obtain the water-based polyamide wax thickener.

[0042] The heat stabilizer is: a polyamide resin obtained by reacting n-octanoic acid and 4,4'-diaminodicyclohexylmethane.

[0043] Preparation Example 2

[0044] The thickener is water-based polyamide wax, and the method comprises the following steps:

[0045] S1: Add 100 g of heat stabilizer, 400 g of water-based polyamide wax slurry and 250 g of propylene glycol n-propyl ether into a reaction kettle, and heat up to 125 °C until the heat stabilizer and the water-based polyamide wax slurry are completely dissolved in the corresponding propylene glycol n-propyl ether;

[0046] S2: Then slowly add 30 g of octadecylamine and 25 g of dodecylamine. After the feeding is completed, start to cool down. When the temperature drops to 75 °C, add 80 g of sodium lauryl alcohol polyoxyethylene ether sulfate, and then keep stirring and dispersing at this temperature to obtain the first reaction material;

[0047] S3: Heat deionized water to 85 °C, and then slowly add the first reaction material dispersed in S2 into 1000 ml of deionized water after heating. Control the stirring speed at 800 rmp, and stop stirring when the temperature of the mixed solution drops below 60 °C;

[0048] S4: Finally, cool to room temperature to obtain the water-based polyamide wax thickener.

[0049] The heat stabilizer is: a polyamide resin obtained by reacting n-decanoic acid and 4,4'-diaminodicyclohexylmethane.

[0050] Preparation Example 3

[0051] The thickener is aqueous polyamide wax, and the method comprises the following steps:

[0052] S1: Add 100 g of heat stabilizer, 400 g of aqueous polyamide wax slurry and 250 g of propylene glycol monobutyl ether into a reaction kettle, and heat up to 125 °C until the heat stabilizer and the aqueous polyamide wax slurry are completely dissolved in the corresponding propylene glycol monobutyl ether;

[0053] S2: Then slowly add 30 g of amine octane and 25 g of N - diethylethanolamine. After the feeding is completed, start to cool down. When the temperature drops to 75 °C, add 80 g of polyoxyethylated nonylphenyl ether, and then keep stirring and dispersing at this temperature to obtain the first reaction material;

[0054] S3: Heat deionized water to 85 °C, and then slowly add the first reaction material dispersed in S2 into 1000 ml of deionized water after heating. Control the stirring speed at 800 rmp, and stop stirring when the temperature of the mixed solution drops below 60 °C;

[0055] S4: Finally, cool to room temperature to obtain the aqueous polyamide wax thickener.

[0056] The heat stabilizer is: a polyamide resin obtained by reacting 12 - hydroxystearic acid and 4,4'-diaminodicyclohexylmethane.

[0057] Preparation Example 4

[0058] The thickener is aqueous polyamide wax, and the method comprises the following steps:

[0059] S1: Add 100 g of heat stabilizer, 400 g of aqueous polyamide wax slurry and 250 g of propylene glycol monobutyl ether into a reaction kettle, and heat up to 125 °C until the heat stabilizer and the aqueous polyamide wax slurry are completely dissolved in the corresponding propylene glycol monobutyl ether;

[0060] S2: Then slowly add 30 g of amine octane and 25 g of N - diethylethanolamine. After the feeding is completed, start to cool down. When the temperature drops to 75 °C, add 80 g of polyoxyethylated nonylphenyl ether, and then keep stirring and dispersing at this temperature to obtain the first reaction material;

[0061] S3: Heat deionized water to 85 °C, and then slowly add the first reaction material dispersed in S2 into 1000 ml of deionized water after heating. Control the stirring speed at 800 rmp, and stop stirring when the temperature of the mixed solution drops below 60 °C;

[0062] S4: Finally, cool to room temperature to obtain the aqueous polyamide wax thickener.

[0063] The heat stabilizer is: a polyamide resin obtained by reacting 12-hydroxy stearic acid and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane.

[0064] Preparation Example 5

[0065] The thickener is a water-based polyamide wax, and the method comprises the following steps:

[0066] S1: Add 100 g of the heat stabilizer, 400 g of the water-based polyamide wax slurry and 250 g of propylene glycol monobutyl ether into a reaction kettle, heat up to 125 °C until the heat stabilizer and the water-based polyamide wax slurry are completely dissolved in the corresponding propylene glycol monobutyl ether;

[0067] S2: Then slowly add 10 g of amine octane, 15 g of dodecylamine and 18 g of octadecylamine. After the feeding is completed, start to cool down. When the temperature drops to 75 °C, add 80 g of polyoxyethylated nonyl phenyl ether, and then keep stirring and dispersing at this temperature to obtain the first reaction material;

[0068] S3: Heat deionized water to 85 °C, and then slowly add the first reaction material dispersed in S2 into 1000 ml of the heated deionized water. Control the stirring speed at 800 rmp, and stop stirring when the temperature of the mixed solution drops below 60 °C;

[0069] S4: Finally, cool to room temperature to obtain the water-based polyamide wax thickener.

[0070] The heat stabilizer is: a polyamide resin obtained by reacting 12-hydroxy stearic acid and a dimer amine.

[0071] Preparation Example 6

[0072] The thickener is a water-based polyamide wax, and the method comprises the following steps:

[0073] S1: Add 100 g of the heat stabilizer, 400 g of the water-based polyamide wax slurry and 250 g of propylene glycol monobutyl ether into a reaction kettle, heat up to 125 °C until the heat stabilizer and the water-based polyamide wax slurry are completely dissolved in the corresponding propylene glycol monobutyl ether;

[0074] S2: Then slowly add 20 g of dodecylamine and 15 g of N-diethylethanolamine. After the feeding is completed, start to cool down. When the temperature drops to 75 °C, add 80 g of alkylaryl polyoxyethylene ether, and then keep stirring and dispersing at this temperature to obtain the first reaction material;

[0075] S3: Heat deionized water to 85 °C, and then slowly add the first reaction material dispersed in S2 into 1000 ml of the heated deionized water. Control the stirring speed at 800 rmp, and stop stirring when the temperature of the mixed solution drops below 60 °C;

[0076] S4: Finally, cool to room temperature to obtain the aqueous polyamide wax thickener.

[0077] The heat stabilizer is a polyamide resin obtained by reacting capric acid with 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane.

[0078] Example 1

[0079] A preparation method of an acid and alkali resistant and environmentally friendly inorganic coating further includes the following steps:

[0080] S1: Grind 30 g of quartz powder with a mesh size of 500 and 25 g of sodium silicate to a fineness of less than 10 μm, and then mix to obtain a mixture.

[0081] S2: Add the mixture obtained in step S1 to 15 g of nano-scale alkaline silica sol with an average particle size of 15 nm, a sodium oxide mass fraction of ≤0.25%, a viscosity of ≤15 mPa·s, and a pH of 8.0, and add 30 ml of deionized water and stir to obtain a slurry.

[0082] S3: Add 1 g of the thickener prepared in Preparation Example 1, 0.5 g of sodium lignosulfonate, and 1 g of sodium methylsilanolate to the slurry obtained in step S2 and stir evenly to obtain the acid and alkali resistant and environmentally friendly inorganic coating.

[0083] Example 2

[0084] A preparation method of an acid and alkali resistant and environmentally friendly inorganic coating further includes the following steps:

[0085] S1: Grind 30 g of calcium carbonate with a mesh size of 500 and 25 g of sodium silicate to a fineness of less than 10 μm, and then mix to obtain a mixture.

[0086] S2: Add the mixture obtained in step S1 to 15 g of nano-scale alkaline silica sol with an average particle size of 18 nm, a sodium oxide mass fraction of ≤0.25%, a viscosity of ≤15 mPa·s, and a pH of 8.0, and add 30 ml of deionized water and stir to obtain a slurry.

[0087] S3: Add 1 g of the thickener prepared in Preparation Example 2, 0.5 g of sodium lignosulfonate, and 1 g of sodium methylsilanolate to the slurry obtained in step S2 and stir evenly to obtain the acid and alkali resistant and environmentally friendly inorganic coating.

[0088] Example 3

[0089] A preparation method of an acid and alkali resistant and environmentally friendly inorganic coating further includes the following steps:

[0090] S1: Grind 30 g of titanium dioxide with a mesh size of 500 and 25 g of potassium silicate to a fineness of less than 10 μm, and then mix to obtain a mixture.

[0091] S2: Add the mixture obtained in step S1 to 15 g of nano-scale alkaline silica sol with an average particle size of 18 nm, a sodium oxide mass fraction of ≤0.25%, a viscosity of ≤15 mPa·s, and a pH of 8.0, and add 30 ml of deionized water and stir to obtain a slurry.

[0092] S3: Add 1 g of thickener, 0.5 g of sodium lignosulfonate, and 1 g of sodium methylsilanolate prepared in Preparation Example 3 to the slurry obtained in step S2 and stir evenly to obtain an acid- and alkali-resistant environmentally friendly inorganic coating.

[0093] Example 4

[0094] A preparation method of an acid- and alkali-resistant environmentally friendly inorganic coating further includes the following steps:

[0095] S1: Grind 30 g of 500-mesh titanium dioxide and 25 g of potassium silicate to a fineness of less than 10 μm, and then mix to obtain a mixture.

[0096] S2: Add the mixture obtained in step S1 to 15 g of nano-scale alkaline silica sol with an average particle size of 10 nm, a sodium oxide mass fraction of ≤0.25%, a viscosity of ≤15 mPa·s, and a pH of 8.0, and add 30 ml of deionized water and stir to obtain a slurry.

[0097] S3: Add 1 g of thickener, 0.5 g of maleic acid-acrylic acid copolymer, and 1 g of sodium methylsilanolate prepared in Preparation Example 4 to the slurry obtained in step S2 and stir evenly to obtain an acid- and alkali-resistant environmentally friendly inorganic coating.

[0098] Example 5

[0099] A preparation method of an acid- and alkali-resistant environmentally friendly inorganic coating further includes the following steps:

[0100] S1: Grind 30 g of 500-mesh barium sulfate and 25 g of potassium silicate to a fineness of less than 10 μm, and then mix to obtain a mixture.

[0101] S2: Add the mixture obtained in step S1 to 15 g of nano-scale alkaline silica sol with an average particle size of 12 nm, a sodium oxide mass fraction of ≤0.25%, a viscosity of ≤15 mPa·s, and a pH of 8.5, and add 30 ml of deionized water and stir to obtain a slurry.

[0102] S3: Add 1 g of thickener, 0.5 g of maleic acid-acrylic acid copolymer, and 1 g of sodium methylsilanolate prepared in Preparation Example 5 to the slurry obtained in step S2 and stir evenly to obtain an acid- and alkali-resistant environmentally friendly inorganic coating.

[0103] Example 6

[0104] A preparation method of an acid and alkali resistant environmental friendly inorganic coating further comprises the following steps:

[0105] S1: Grind 30 g of titanium dioxide with 800 meshes and 25 g of sodium silicate until the fineness is less than 10 μm, and then mix them to obtain a mixed material;

[0106] S2: Add the mixed material obtained in step S1 into 15 g of nano-scale alkaline silica sol with an average particle size of 15 nm, a mass fraction of sodium oxide ≤ 0.25%, a viscosity ≤ 15 mPa·s, and a pH of 9.0, and add 30 ml of deionized water and stir to obtain a slurry;

[0107] S3: Add 1 g of the thickener prepared in Preparation Example 6, 0.5 g of maleic acid-acrylic acid copolymer, and 1 g of sodium methyl silicate into the slurry obtained in step S2 and stir evenly to obtain the acid and alkali resistant environmental friendly inorganic coating.

[0108] Comparative Example 1

[0109] S1: Grind 30 g of quartz powder with 500 meshes and 25 g of sodium silicate until the fineness is less than 10 μm, and then mix them to obtain a mixed material;

[0110] S2: Add the mixed material obtained in step S1 into 15 g of nano-scale alkaline silica sol with an average particle size of 15 nm, a mass fraction of sodium oxide ≤ 0.25%, a viscosity ≤ 15 mPa·s, and a pH of 8.0, and add 30 ml of deionized water and stir to obtain a slurry;

[0111] S3: Replace 1 g of the thickener prepared in Preparation Example 1 with 1 g of water-based polyamide wax slurry with the model number of PA-600 purchased from Zhejiang Fenghong New Materials Co., Ltd., 0.5 g of sodium lignosulfonate, and 1 g of sodium methyl silicate, add them into the slurry obtained in step S2 and stir evenly to obtain the acid and alkali resistant environmental friendly inorganic coating.

[0112] Comparative Example 2

[0113] S1: Grind 30 g of quartz powder with 500 meshes and 25 g of sodium silicate until the fineness is less than 10 μm, and then mix them to obtain a mixed material;

[0114] S2: Add the mixed material obtained in step S1 into 15 g of nano-scale alkaline silica sol with an average particle size of 15 nm, a mass fraction of sodium oxide ≤ 0.25%, a viscosity ≤ 15 mPa·s, and a pH of 8.0, and add 30 ml of deionized water and stir to obtain a slurry;

[0115] S3: Replace 1 g of the thickener prepared in Preparation Example 1 with 1 g of an acrylic thickener with the model number N-0049 purchased from Foshan Shenghui New Materials Co., Ltd., 0.5 g of sodium lignosulfonate, and 1 g of sodium methylsilanolate, add them to the slurry obtained in Step S2, and stir evenly to obtain an acid- and alkali-resistant environmentally friendly inorganic coating.

[0116] Comparative Example 3

[0117] S1: Grind 30 g of 500-mesh quartz powder and 25 g of sodium silicate to a fineness less than 10 μm, and then mix to obtain a mixture.

[0118] S2: Add the mixture obtained in Step S1 to 15 g of a nanoscale alkaline silica sol with an average particle size of 15 nm, a sodium oxide mass fraction ≤ 0.25%, a viscosity ≤ 15 mPa·s, and a pH of 8.0, and add 30 ml of deionized water and stir to obtain a slurry.

[0119] S3: Add 0.5 g of sodium lignosulfonate and 1 g of sodium methylsilanolate to the slurry obtained in Step S2 and stir evenly to obtain an acid- and alkali-resistant environmentally friendly inorganic coating.

[0120] Comparative Example 4

[0121] S1: Grind 30 g of 500-mesh quartz powder and 25 g of sodium silicate to a fineness less than 10 μm, and then mix to obtain a mixture.

[0122] S2: Add the mixture obtained in Step S1 to 15 g of a nanoscale alkaline silica sol with an average particle size of 15 nm, a sodium oxide mass fraction ≤ 0.25%, a viscosity ≤ 15 mPa·s, and a pH of 8.0, and add 30 ml of deionized water and stir to obtain a slurry.

[0123] S3: Add 1 g of the thickener prepared in Preparation Example 1, 0.5 g of sodium lignosulfonate, and 1 g of sodium methylsilanolate to the slurry obtained in Step S2 and stir evenly to obtain an acid- and alkali-resistant environmentally friendly inorganic coating.

[0124] In Preparation Example 1, no heat stabilizer is added during the preparation of the waterborne polyamide wax thickener.

[0125] Comparative Example 5

[0126] S1: Grind 30 g of 500-mesh quartz powder and 25 g of sodium silicate to a fineness less than 10 μm, and then mix to obtain a mixture.

[0127] S2: Add the mixture obtained in Step S1 to 15 g of a nanoscale alkaline silica sol with an average particle size of 15 nm, a sodium oxide mass fraction ≤ 0.25%, a viscosity ≤ 15 mPa·s, and a pH of 8.0, and add 30 ml of deionized water and stir to obtain a slurry.

[0128] S3: Add 1 g of the thickener prepared in Preparation Example 1, 0.5 g of sodium lignosulfonate, and 1 g of sodium methylsilanolate to the slurry obtained in Step S2 and stir evenly to obtain an acid- and alkali-resistant environmentally friendly inorganic coating.

[0129] Among them, the heat stabilizer added during the preparation of the aqueous polyamide wax thickener in Preparation Example 1 was replaced with an organotin heat stabilizer with the model number 181# purchased from Henan Tianchou Chemical Products Co., Ltd.

[0130] Comparative Example 6

[0131] S1: Grind 30 g of 500-mesh quartz powder and 25 g of sodium silicate to a fineness of less than 10 μm, and then mix to obtain a mixed material.

[0132] S2: Add the mixed material obtained in Step S1 to 15 g of industrial-grade silica sol with the CAS number 112926-00-8 purchased from Wuhan Jiyesheng Chemical Co., Ltd., and add 30 ml of deionized water and stir to obtain a slurry.

[0133] S3: Add 1 g of the thickener prepared in Preparation Example 1, 0.5 g of sodium lignosulfonate, and 1 g of sodium methylsilanolate to the slurry obtained in Step S2 and stir evenly to obtain an acid- and alkali-resistant environmentally friendly inorganic coating.

[0134] Test items:

[0135] Perform performance tests on the coatings prepared in Examples 1-6 and Comparative Examples 1-6. The specific test items include adhesion, hardness, reflectivity, thermal shock test, thermal storage performance test, and corrosion resistance test. The specific test results are shown in Table 1:

[0136] In this test example, the adhesion test method refers to ASTM D-3359 "Standard Test Method for Evaluating Adhesion by Tape Test".

[0137] The hardness test refers to GB / T 6739-2006 "Determination of Film Hardness by Pencil Method for Paints and Varnishes".

[0138] The reflectivity is measured using the test instrument Fluxdata to obtain the reflectivity value in the wavelength range of 500-1000 nm. Before the test, it should be ensured that the coating surface has no damage.

[0139] The thermal shock test conditions are: 25°C / 25% RH, 5 min → 65°C / 90% RH, 2 h → 25°C / 25% RH, 2 h → -20°C, 2 h → 25°C / 25% RH, 5 min. Repeat the above process 6 times and then test the adhesion effect. The specific rating standard refers to ASTM D-3359 "Standard Test Method for Evaluating Adhesion by Tape Test".

[0140] Heat storage performance test: Seal the material and place it in an oven at 50 °C for two weeks;

[0141] Acid resistance: Test according to the method in Standard GBT 50393-2017. Observe the foaming time. The test parameters are: 5wt% H2SO4 solution. Observe how long it can remain non-foaming, non-rusting, non-peeling, and non-cracking;

[0142] Alkali resistance: Test according to the method in Standard GBT 50393-2017. Observe the foaming time. The test parameters are: 5wt% NaOH solution. Observe how long it can remain non-foaming, non-rusting, non-peeling, and non-cracking.

[0143] Table 1

[0144]

[0145] In summary, the coating prepared with the coating material of the present invention has excellent acid and alkali resistance, and the coating has strong adhesion and hardness. At the same time, after adding the thickener in the preparation example, the prepared coating material has excellent thermal shock performance, and at the same time has a low reflectivity, between 1.60 - 1.65, while the reflectivity in the comparative example is as high as 2.89. This proves that by adding the waterborne polyamide wax thickener in the preparation process of the coating material, the phenomena of stratification and sedimentation of the waterborne coating can be effectively avoided, thereby further improving the overall stability and fluidity of the coating material, and having high social use value and application prospects.

[0146] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A preparation method of an acid and alkali resistant environmentally friendly inorganic coating, characterized in that, It includes the following steps: S1: Grind 30 g of quartz powder with a mesh size of 500 and 25 g of sodium silicate until the fineness is less than 10 μm, and then mix them to obtain a mixed material; S2: Add the mixed material obtained in step S1 to 15 g of nano-scale alkaline silica sol with an average particle size of 15 nm, a mass fraction of sodium oxide ≤ 0.25%, a viscosity ≤ 15 mPa·s, and a pH of 8.0, and add 30 ml of deionized water and stir to obtain a slurry; S3: Add 1 g of thickener, 0.5 g of sodium lignosulfonate, and 1 g of sodium methylsilanolate to the slurry obtained in step S2 and stir evenly to obtain an acid and alkali resistant environmentally friendly inorganic coating; The thickener is a water-based polyamide wax, and it includes the following steps: S1: Add 100 g of heat stabilizer, 400 g of water-based polyamide wax slurry, and 250 g of propylene glycol monobutyl ether to a reaction kettle, and heat up to 125 °C until the heat stabilizer and water-based polyamide wax slurry are completely dissolved in the corresponding propylene glycol monobutyl ether; S2: Slowly add 30 g of amine octane and 25 g of dodecylamine, start cooling after the feeding is completed, add 80 g of fatty alcohol polyoxyethylene ether when the temperature drops to 75 °C, and then stir and disperse at a constant temperature at this temperature to obtain a first reaction material; S3: Heat deionized water to 85 °C, and then slowly add the first reaction material dispersed in S2 to 1000 ml of heated deionized water, control the stirring speed at 800 rmp, and stop stirring when the temperature of the mixed solution drops below 60 °C; S4: Finally, cool to room temperature to obtain a water-based polyamide wax thickener; The heat stabilizer is: a polyamide resin obtained by reacting n-octanoic acid and 4,4'-diaminodicyclohexylmethane.

Images