Inorganic resin and method for producing the same

Abstract

The present application relates to an inorganic resin and a preparation method thereof. The preparation method comprises nano-modification and nano-coating: mixing silica sol and organic acid, reacting, adding potassium silicate and water, continuing to react, cooling, adding silane coupling agent, and then reacting. The organic acid is selected from tartaric acid, citric acid or a combination of both. The present application passivates part of the hydroxyl groups on the surface of silica colloidal particles through nano-modification and nano-coating technology; introduces branched chains capable of self-crosslinking, which play a bridging role in the curing process of silica sol, reducing the shrinkage rate in the film-forming process, reducing cracking, and improving the film-forming performance of silica sol. The polar functional groups introduced by the nano-modification and nano-coating technology have a certain degree of improvement in the adhesion of the inorganic resin; and the branched chains grafted to the surface of the silica colloidal particles that do not participate in the reaction can be embedded in the silicon-oxygen network structure after the silica sol is cured, providing flexibility to the coating film, thereby improving the toughness of the inorganic resin coating.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to an inorganic resin and its preparation method. Background Technology

[0002] Organic resins refer to organic polymers that soften or melt when heated, tend to flow under external force when softened, and are usually solid or semi-solid at room temperature. They are generally insoluble in water but soluble in organic solvents. Organic resins possess good plasticity, decorative properties, and toughness. However, organic resins are a non-renewable resource. The main raw materials for organic substances come from resources such as coal, petroleum, and natural gas. Processing these materials generates a large amount of byproducts, volatile solvents, and residual monomers, causing environmental pollution and wasting significant resources and energy. Furthermore, organic resins have poor weather resistance and are prone to aging under high temperatures or strong ultraviolet radiation, which damages their properties and affects their service life.

[0003] Inorganic resins are substances that use water as a solvent, cure at room temperature, form a coating structure on the surface of a substrate material, and do not release volatile organic compounds during use. Inorganic resins can form a protective coating on the substrate surface, acting as a physical barrier to prevent external corrosive media from penetrating the substrate structure. Inorganic resins possess advantages such as excellent adhesion, good weather resistance, antibacterial properties, high temperature resistance, breathability, and environmental friendliness, and are widely used in coatings, waterproofing materials, and coating protection.

[0004] However, existing inorganic resins have the following shortcomings: poor storage and stability; large shrinkage during film formation, resulting in brittle and easily cracked coatings and poor decorative effects; and serious salt return and whitening phenomena caused by the soluble inorganic salts they contain. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an inorganic resin and its preparation method to solve the technical problems of poor storage and stability of the above-mentioned inorganic resin, brittle and easily cracked coating film, and salt return and whitening phenomenon.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] In some embodiments, the present invention provides a method for preparing an inorganic resin, comprising:

[0008] Nanomodification and nanocoating: Mix silica sol and organic acid, react, add potassium silicate and water, continue the reaction, cool down, add silane coupling agent, and then react again, wherein the organic acid is selected from tartaric acid, citric acid or a combination of the two.

[0009] In some embodiments, the mass ratio of the silica sol to the organic acid is 50-70:5-10.

[0010] In some embodiments, the reaction is carried out at a temperature of 70-90°C for 0.5-1.5 hours.

[0011] In some embodiments, the mass ratio of potassium silicate to organic acid is 10-20:5-10.

[0012] In some embodiments, the mass ratio of water to organic acid is 10-20:5-10.

[0013] In some embodiments, the reaction continues at a temperature of 70-90°C for 0.5-1.5 hours.

[0014] In some embodiments, the temperature is lowered to 50-60°C.

[0015] In some embodiments, the silane coupling agent is selected from γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, or a combination thereof.

[0016] In some embodiments, the mass ratio of the silane coupling agent to the organic acid is 3-5:5-10.

[0017] In some embodiments, the reaction then proceeds for 1-3 hours.

[0018] In some embodiments, the present invention also provides an inorganic resin prepared according to the preparation method described above.

[0019] The beneficial effects of this invention are as follows:

[0020] This invention passivates some of the hydroxyl groups on the surface of silica particles through nano-modification and nano-encapsulation technology; at the same time, it introduces self-crosslinking branches, which play a bridging role in the curing process of silica sol, reducing the shrinkage rate during the curing and film formation process, reducing cracking, and improving the film-forming performance of silica sol.

[0021] To address the technical problems of poor storage stability of inorganic resins, such as precipitation, stratification, and gelation, this invention introduces side chains with polar functional groups through nano-modification and nano-encapsulation technology. These side chains generate charge effects and inhibit the self-polymerization process of silica sol through electrostatic repulsion, thereby improving the storage stability of silica sol. The side chains grafted onto the surface of silica particles that do not participate in the reaction can hinder the contact between particles before the silica sol solidifies due to steric hindrance, thus improving the storage stability of silica sol and consequently enhancing the storage stability of the inorganic resin coating.

[0022] In this invention, the polar functional groups introduced through nano-modification and nano-encapsulation technology improve the adhesion of inorganic resin to a certain extent; while the non-reactive side chains grafted onto the surface of silica particles can be embedded in the silica network structure after the silica sol is cured, providing flexibility to the coating film and thus improving the toughness of the inorganic resin coating. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] This application provides a method for preparing an inorganic resin, comprising:

[0025] Nano-modification and nano-coating: Mix silica sol and organic acid, and react at 70-90℃ for 0.5-1.5h, with the mass ratio of silica sol to organic acid being 50-70:5-10;

[0026] Add potassium silicate and water, and continue the reaction at 70-90℃ for 0.5-1.5h. The mass ratio of potassium silicate to organic acid is 10-20:5-10, and the mass ratio of water to organic acid is 10-20:5-10.

[0027] Cool to 50-60℃, add silane coupling agent, and then react for 1-3 hours. The organic acid is selected from tartaric acid, citric acid, or a combination of the two. The silane coupling agent is selected from γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, or a combination of the two. The mass ratio of silane coupling agent to organic acid is 3-5:5-10.

[0028] In some embodiments, the present invention also provides an inorganic resin prepared according to the preparation method described above.

[0029] The present invention will be described in detail below through specific examples. It should also be understood that the following examples are only for specific illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are only examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below. It should be understood that in the following examples, only the specific cases where the organic acid is selected from tartaric acid and citric acid as organic acids alone are listed. Those skilled in the art can also select a combination of tartaric acid and citric acid as organic acids according to actual needs. In the following examples, only the specific cases where γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane are listed as silane coupling agents are listed. Those skilled in the art can also select a combination of γ-aminopropyltriethoxysilane and γ-glycidoxypropyltrimethoxysilane as silane coupling agents according to actual needs.

[0030] Example 1

[0031] A method for preparing an inorganic resin, the specific steps of which are as follows:

[0032] Nano-modification and nano-coating: 55 parts by mass of silica sol (commercially available, content 30%) and 6 parts by mass of tartaric acid were added to a reactor, heated to 70°C, and reacted at 70°C for 1 hour; 20 parts by mass of potassium silicate (modulus 3.4) and 16 parts by mass of deionized water were added to the reactor, and the reaction was continued at 70°C for 1 hour; the reactor was cooled to 60°C, and 3 parts by mass of γ-aminopropyltriethoxysilane were added to the reactor, and the reaction was continued at 60°C for 2 hours to obtain an inorganic resin.

[0033] Example 2

[0034] A method for preparing an inorganic resin, the specific steps of which are as follows:

[0035] Nano-modification and nano-coating: 60 parts by mass of silica sol (commercially available, content 30%) and 8 parts by mass of citric acid were added to a reactor, heated to 90°C, and reacted at 90°C for 1 hour; 15 parts by mass of potassium silicate (modulus 3.4) and 13 parts by mass of deionized water were added to the reactor, and the reaction was continued at 90°C for 1 hour; the reactor was cooled to 50°C, and 4 parts by mass of γ-glycidyl etheroxypropyltrimethoxysilane were added to the reactor, and the reaction was continued at 50°C for 2 hours to obtain an inorganic resin.

[0036] Example 3

[0037] A method for preparing an inorganic resin, the specific steps of which are as follows:

[0038] Nano-modification and nano-coating: 65 parts by mass of silica sol (commercially available, content 30%) and 10 parts by mass of tartaric acid were added to a reactor, heated to 80°C, and reacted at 80°C for 1 hour; 10 parts by mass of potassium silicate (modulus 3.4) and 10 parts by mass of deionized water were added to the reactor, and the reaction was continued at 80°C for 1 hour; the reactor was cooled to 55°C, and 3 parts by mass of γ-aminopropyltriethoxysilane were added to the reactor, and the reaction was continued at 55°C for 2 hours to obtain an inorganic resin.

[0039] Comparative Example 1

[0040] The aqueous inorganic resin was prepared according to the method in Example 1 of CN103602107A, and the specific steps are as follows:

[0041] 12.35 parts of deionized water were added to a dispersion vessel. 56 parts of potassium silicate (modulus 3.3, silica content 19 wt%), 16 parts of silica sol (silica content 25 wt%, sodium oxide content 0.2 wt%), and 2 parts of lithium silicate (modulus 4.7, silica content 19 wt%) were added while stirring at 800 rpm. After the addition was complete, stirring was continued for 5 min. Then, 3 parts of trimethoxysilane coupling agent were slowly added dropwise over 15 min. The stirring speed was reduced, and stirring was maintained at 500 rpm for 2 h. The mixture was then allowed to stand for 24 h. Next, 8 parts of pure acrylic emulsion, 0.65 parts of deionized water, 0.04 parts of fluorocarbon surfactant, and 0.5 parts of diallyl dimethyl ammonium chloride polymer were slowly added at 500 rpm. Stirring was maintained for 1 h. The mixture was then filtered through a 150-mesh silk filter cloth to obtain an aqueous inorganic resin.

[0042] The difference between Comparative Example 1 and the Example is that Comparative Example 1 incorporates pure acrylic elastic emulsion, which is not strictly speaking an inorganic resin and has not undergone nano-modification. The Example, however, does not incorporate any organic emulsion and employs silica sol surface grafting modification technology, a domestic first.

[0043] Comparative Example 2

[0044] A commercially available silica sol has not undergone nano-coating.

[0045] Performance testing

[0046] The inorganic resin coatings prepared in Examples 1-3, the water-based inorganic resin prepared in Comparative Example 1, and the silica sol prepared in Comparative Example 2 were tested for film-forming properties, hardness, water resistance, alkali resistance, high-temperature storage stability, room-temperature storage stability, and freeze-thaw cycle tests. The results are shown in Table 1.

[0047] The film-forming performance testing steps are as follows: A 120*50*0.28mm tinplate is used. Before use, the tinplate needs to be sanded to remove oil stains, as grease on the tinplate will affect the adhesion performance of the inorganic resin. 2 grams of inorganic resin are dropped onto the tinplate and then coated evenly. The tinplate coated with inorganic resin is placed in an environment with a temperature >5℃. After 24 hours, it is observed whether the inorganic resin on the tinplate has formed a film. The criteria for judging film formation are: the inorganic resin forms a continuous, transparent film with a certain strength and is firmly bonded to the tinplate.

[0048] The hardness detection steps are as follows: Apply an inorganic resin paint film on three test panels, dry for 7 days at a temperature of (23±2)°C and a relative humidity of (50±5)%, complete the preparation of the paint film. Insert a pencil into the experimental instrument and fix it with a clamp, keep the instrument horizontal. When the tip of the pencil touches the paint film, immediately push the pencil in a slow and uniform speed away from the operator, push for a sufficient distance for visual observation; if defects appear, reduce the hardness of the pencil and repeat the test until no more defects occur; if no defects appear, replace the pencil with a higher hardness in an area where the test has not been carried out and repeat the test until at least 3 mm of defects appear. The hardness of the inorganic resin is represented by the hardness of the hardest pencil that does not cause defects in the paint film.

[0049] The water resistance detection steps are as follows: Apply an inorganic resin paint film on three test panels, dry for 7 days at a temperature of (23±2)°C and a relative humidity of (50±5)%, complete the preparation of the paint film. Add deionized water at 23°C to a water tank (maintain this temperature during the experiment), place the three test panels in it, and immerse 2 / 3 of the length of each test panel in the water; after soaking for 7 days, take out the test panels from the tank, blot the surface water with filter paper, immediately observe the test panels and record whether there are phenomena such as loss of gloss, color change, blistering, wrinkling, peeling, etc. and the recovery time. At least two of the three test panels meeting the requirements are regarded as qualified.

[0050] The alkali resistance detection steps are as follows: Apply the inorganic resin on three non-asbestos fiber cement boards (size: 150 mm×70 mm, thickness: 3 mm), dry for 7 days at a temperature of (23±2)°C and a relative humidity of (50±5)%. After the curing is completed, seal the four edges and the back of the test panel with a mixture of paraffin and rosin (mass ratio 1:1), the sealing edge width is 2 mm - 4 mm. Add a saturated aqueous solution of calcium hydroxide to a water tank, and immerse 2 / 3 of the length of each test panel in the solution, cover and seal. After 7 days, take out the test panels, rinse them with water, blot the surface water with filter paper, and immediately observe whether there are phenomena such as color change, bubbling, peeling, powdering, softening, etc. on the surface;

[0051] The high-temperature storage stability detection steps are as follows: Stir the inorganic resin evenly and pour it into a clean large-mouth glass bottle with a volume of 500 mL, the filling amount is 2 / 3 of the container. After covering the lid, put the sample can into a constant-temperature oven, and keep the temperature of the freezer at (50±2)°C; take it out after the specified time, place it at room temperature, open the container lid, and gently stir the sample. There is no caking or agglomeration phenomenon in the sample.

[0052] The steps for testing the stability of storage at room temperature are as follows: After stirring the inorganic resin evenly, pour it into a clean, wide-mouthed glass bottle with a sealed cap with a volume of 500mL, filling the bottle to 2 / 3 full. After sealing the cap, place the sample container in a constant temperature chamber, and maintain the temperature of the freezer at (23±2)℃. After the specified time, take it out, open the container cap, stir the sample, and the sample should show no clumping or agglomeration.

[0053] The freeze-thaw cycle test procedure is as follows: After the inorganic resin is stirred evenly, it is poured into a clean, wide-mouthed glass bottle with a sealed cap with a volume of 500mL, filling the bottle to 2 / 3 capacity. After sealing the cap, the sample container is placed in a freezer at a temperature of (-5±2)℃. The sample container is placed in the freezer for 18 hours and then removed. It is then placed at (23±2)℃ for 6 hours, which constitutes one cycle. After three cycles, the container is opened, the sample is stirred thoroughly, and the presence of hard lumps, agglomeration, and freezing phenomena is observed.

[0054] Table 1 Test Results

[0055]

[0056] As shown in Table 1, compared with Comparative Example 1 (without nano-modification), the water resistance and alkali resistance of Example 1 are significantly improved. This result demonstrates that the present invention improves the water resistance and alkali resistance of the coating through nano-modification technology.

[0057] As shown in Table 1, compared with Comparative Example 2 (without nano-coating), the film-forming performance of Example 1 is significantly improved. This result indicates that the present invention passivates some hydroxyl groups on the surface of silica particles through nano-encapsulation technology; simultaneously, it introduces self-crosslinking branches, which act as bridges during the curing process of the silica sol, reducing shrinkage during curing and film formation, minimizing cracking, and improving the film-forming performance of the silica sol.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing an inorganic resin, characterized in that, The inorganic resin is used for separate brushing to form an inorganic resin paint film; the process includes the following steps: (1) Mix silica sol with organic acid and react them at 70–90°C for 0.5–1.5 h; wherein the organic acid is selected from tartaric acid, citric acid or a combination of the two, and the mass ratio of silica sol to organic acid is 50–70:5–10; (2) Add potassium silicate and water to the reaction system of step (1) and continue the reaction at 70–90°C for 0.5–1.5 h; wherein the mass ratio of potassium silicate to organic acid is 10–20:5–10; (3) Cool the reaction system to 50–60℃; (4) Add a silane coupling agent to the cooled reaction system and then react for 1–3 h, wherein the silane coupling agent is selected from γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane or a combination thereof, and the mass ratio of the silane coupling agent to the organic acid is 3–5:5–10.

2. An inorganic resin, characterized in that, It is prepared by the preparation method described in claim 1.

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