Ablation-resistant coating primer, preparation method thereof and coating

Abstract

The invention discloses an ablation-resistant coating primer, a preparation method thereof and a coating, and relates to the field of thermal insulation coatings, self-made epoxy modified silicon resin and modified siloxane are introduced and compounded with functional filler and auxiliaries, and the ablation-resistant coating primer with high bonding capacity, light weight, temperature resistance and thermal insulation is prepared. The ablation-resistant coating primer can be used for preparing a coating. The ablation-resistant coating primer can effectively reduce the brushing surface density, meets the lightweight requirement of thermal insulation materials, and is simple in preparation method and wide in application range.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of heat-resistant coating, in particular to a kind of ablation-resistant coating primer and preparation method thereof and a kind of coating. BACKGROUND

[0002] Heat-resistant coating has important application in high-temperature insulation field, and can provide thermal protection for the outer surface of materials. As a special kind of heat-resistant coating, ablation-resistant coating can dissipate heat through thermal degradation or ablation of the coating itself or the coating formed by coating, to achieve thermal protection of materials. Generally speaking, ablation-resistant coating has simple process, less influence from product structure, low cost and short coating cycle, and is widely used as thermal protection material.

[0003] The commonly used high-performance ablation-resistant coating at present is based on silicone polymer as matrix film-forming material, and various functional powders are compounded to achieve it. The heat-resistant temperature can reach above 800℃, showing excellent heat-resistant performance. However, the silicone polymer generally has poor wettability with carbon fiber composite materials, aluminum alloy, titanium alloy and other substrate materials, and has insufficient adhesion. Under the environment of high-temperature airflow scouring and vibration, there is a risk of coating peeling, so the interface between the coating and the substrate needs to be treated to improve the interfacial force and achieve the purpose of enhancing the bonding strength of the coating. In addition, under the environment of high temperature for a long time, the temperature of the substrate may reach above 200℃, which requires the coating primer to have certain temperature resistance.

[0004] The patent disclosed in Patent No. CN117965043A only focuses on the impact resistance and room temperature thermal insulation effect of the primer, and does not involve the temperature resistance and matching performance with other organic silicon thermal protection materials. The patent disclosed in Patent No. CN116716017A only focuses on the self-cleaning and anti-fouling ability of the super anti-fouling and thermal insulation composite coating primer, and also does not involve the temperature resistance and matching performance with other organic silicon thermal protection materials. The patent disclosed in Patent No. CN110041808A only involves the water-based primer and thermal insulation performance, and the patent disclosed in Patent No. CN113122110A only involves the water resistance, thermal insulation performance and performance of preventing the collapse of the coating of the epoxy primer coating, and none of them involves the temperature resistance and matching performance with other organic silicon thermal protection materials. The patent disclosed in Patent No. CN103102797A involves the high-temperature ablation-resistant primer, but needs to be used in cooperation with the topcoat, and does not involve the lightweight and thermal insulation characteristics. The patents disclosed in Patent Nos. CN107177307A and CN107201171A only involve the ablation resistance of the coating itself, do not have the bottom coating adhesion ability, and need high-temperature curing. The patent disclosed in Patent No. CN111534220A is composed of two coatings, the outer part is a temperature-resistant coating, and the inner part is a thermal insulation coating, does not have the strong adhesion effect and adhesion force of the bottom coating, and does not involve the high-temperature bonding strength. The patent disclosed in Patent No. CN118146695A is mainly used for temperature resistance and corrosion resistance, and has a temperature resistance of 250 DEG C, and does not have the lightweight, thermal insulation and strong adhesion performance.

[0005] In summary, the conventional bottom coating agent can improve the coating adhesion, but often only focuses on the bonding strength with the topcoat, most of which have the problems of insufficient temperature resistance (<100 DEG C) and limited adaptation range. It is found through experiments that the thermal expansion coefficients of the ablation-resistant coating and the bottom coating are inconsistent, the coating and the bottom coating contact surface cracks, and cannot adapt to the ablation-resistant and thermal insulation coating, which cannot enhance the adhesion of the coating and the substrate. Therefore, it is of great significance to develop and research a kind of ablation-resistant coating bottom coating agent with strong adhesion, vibration resistance, lightweight, temperature resistance and thermal insulation by modifying the composition of the coating. SUMMARY

[0006] The purpose of the present application is to provide an ablation-resistant coating bottom coating agent, a preparation method thereof and a coating, so as to solve the problems of insufficient adhesion of the current ablation-resistant and thermal insulation coating and the substrate material, insufficient temperature resistance of other types of bottom coating agents, and insufficient lightweight and thermal insulation performance.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: The present application provides a preparation method of an ablation-resistant coating primer in a first aspect, and the method comprises the following steps: (1) preparing an epoxy-modified silicone resin; (2) mixing the epoxy-modified silicone resin with light nano-filler, modified siloxane, drier, silane coupling agent uniformly to prepare an ablation-resistant coating primer base; (3) adding a curing agent and a diluent to the ablation-resistant coating primer base, stirring and mixing uniformly to prepare an ablation-resistant coating primer.

[0008] Preferably, the preparation step of the epoxy-modified silicone resin comprises: dissolving the epoxy resin in twice its mass of dimethylbenzene, and then adding silicone resin and coupling agent for sufficient reaction.

[0009] Preferably, the light nano-filler is one or more of nano-silica aerogel, nano-titanium dioxide, nano-boron carbide, boric acid, phosphorus oxide powder, and mica powder; the particle size of the light nano-filler is 10-80 nm, more preferably 15-50 nm.

[0010] Preferably, the modified siloxane is one or more of alkyl-modified siloxane, amino-modified siloxane, isocyanate-modified siloxane, and acrylic acid-modified siloxane; the molecular weight of the modified siloxane is 5000-10000.

[0011] Preferably, the drier is one of Co-Ce, Co-Zr, and Mn-Ca.

[0012] Preferably, the silane coupling agent is one of KH550 (γ-aminopropyltriethoxysilane), KH560 (γ-glycidyl ether propyltrimethoxysilane), KH570 (γ-methacryloyloxypropyltrimethoxysilane), KH792 (N-β(aminoethyl)-γ-aminopropyltrimethoxysilane), and KH902 (vinyltri(β-methoxyethoxy)silane).

[0013] Preferably, the curing agent is one or more of azo polymer, organic tin, organic zinc, organic aluminum, tetrabutyl titanate, and polyamide.

[0014] Preferably, the mass ratio of the epoxy-modified silicone resin, light nano-filler, modified siloxane, drier, and silane coupling agent is (60-120):(10-25):(20-50):(0.05-1.5):(2-3).

[0015] Preferably, the amount of the curing agent is 0.5%-2% of the mass of the epoxy-modified silicone resin.

[0016] Preferably, the diluent is one or more of ethyl acetate, butyl acetate, toluene, xylene, 120# solvent oil.

[0017] Preferably, after the curing agent is added and mixed uniformly, the ablation-resistant coating primer needs to be used within 1-2 hours according to different curing systems.

[0018] The present application provides, in a second aspect, an ablation-resistant coating primer prepared by the method described in the first aspect of the present application.

[0019] The present application provides, in a third aspect, a coating layer prepared by diluting the ablation-resistant coating primer prepared by the method described in the first aspect of the present application with a diluent to a desired viscosity, applying the ablation-resistant coating primer to a surface of a base material in a desired thickness by a brushing method, and obtaining the ablation-resistant coating primer coating layer after the brushing is completed.

[0020] Preferably, the diluent is one or more of methanol, n-pentanol, and one or more of ethyl acetate, butyl acetate, toluene, xylene, petroleum ether, 60# solvent oil, and 120# solvent oil.

[0021] Preferably, the brushing method is brushing or spraying.

[0022] Preferably, the thickness of the coating layer is 20-200 um.

[0023] Preferably, after the coating layer is prepared, the subsequent coating layer needs to be applied within 10-40 minutes.

[0024] Compared with the prior art, the method of the present application has the following beneficial effects.

[0025] (1) The self-made epoxy-modified silicone resin prepared by the present application has high adhesion to the modified siloxane, and the decomposition temperature is greater than 380℃, so that the adhesion can be maintained at a temperature not higher than 300℃, which can meet the application environment of the ablation-resistant coating.

[0026] (2) The ablation-resistant coating primer prepared by the present application has high adhesion, thermal expansion matching performance, and wide application range, and at the same time, maintains low density and high efficient heat insulation performance, has certain lightweight heat insulation performance under the premise of maintaining adhesion, can effectively reduce the density of the brushed surface, meets the lightweight requirement of the heat insulation material, and has very important significance for the development of high-temperature heat protection materials.

[0027] (3) The prepared ablation-resistant coating primer has the characteristics of strong bonding (room temperature peeling strength greater than 10 MPa, 200 DEG C peeling strength greater than 5 MPa), light weight (density less than 0.5 ), temperature resistance (temperature resistance grade greater than 300 DEG C), heat insulation (room temperature thermal conductivity coefficient less than 0.05 W / (m K)), and the like, and the primer has certain toughness, can be used in cooperation with other types of organic polymer coatings, the use method is simple, and has important application prospects in the field of heat insulation coatings. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described more clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

[0029] Embodiment 1 (1) The epoxy-modified silicone resin is prepared; (2) 60 parts of the epoxy-modified silicone resin, 10 parts of Tego Glide 420 (polyether-modified polydimethylsiloxane, one of the alkyl-modified siloxanes), 10 parts of nano-silica aerogel, 10 parts of nano-boron oxide, 0.05 parts of Co-Ce catalyst drier and 2 parts of KH550 are weighed according to the mass fraction, to prepare a base material of the ablation-resistant coating primer; (3) 0.3 parts of azo polymer and a proper amount of ethyl acetate and 120# solvent oil (the volume fraction of ethyl acetate is 10%) are added to the above-mentioned base material of the ablation-resistant coating primer to mix uniformly, and are sprayed on two aluminum alloy substrates with a spraying thickness of 20 microns; after being left at room temperature for 10 minutes, one of the aluminum alloy substrates is not treated, and the other is sprayed with 2mm-thick ablation-resistant coating; after being left at room temperature to solidify for 7 days, relevant tests are performed.

[0030] Embodiment 2 (1) The epoxy-modified silicone resin is prepared; (2) 120 parts of the epoxy-modified silicone resin, 25 parts of BYK-310, 20 parts of nano-silica aerogel, 10 parts of nano-boron oxide, 20 parts of mica powder, 1.5 parts of Mn-Ca catalyst drier and 3 parts of KH792 are weighed according to the mass fraction, to prepare a base material of the ablation-resistant coating primer; (3) In the above-mentioned ablation-resistant coating primer base, 2.4 parts of dibutyltin laurate and a suitable amount of butyl acetate and No. 120 solvent oil compounded solvent (10% of ethyl acetate by volume) were added, mixed uniformly, sprayed on two aluminum alloy substrates, the spraying thickness was 20 μm, and after air drying at room temperature for 10 minutes, one aluminum alloy substrate was not treated, and the other was sprayed with 2 mm thick ablation-resistant coating, and after air drying at room temperature for 7 days, relevant tests were carried out.

[0031] Example 3: (1) Epoxy-modified silicone resin was prepared; (2) 120 parts of epoxy-modified silicone resin, 25 parts of BYK-310, 20 parts of nano-silica aerogel, 10 parts of nano-boron oxide, 20 parts of mica powder, 1.5 parts of Mn-Ca catalyst, and 3 parts of KH792 were weighed according to the mass fraction to prepare an ablation-resistant coating primer base; (3) In the above-mentioned ablation-resistant coating primer base, 2.4 parts of dibutyltin laurate and a suitable amount of butyl acetate and No. 120 solvent oil compounded solvent (10% of ethyl acetate by volume) were added, mixed uniformly, sprayed on two aluminum alloy substrates, the spraying thickness was 20 μm, and after air drying at room temperature for 10 minutes, one aluminum alloy substrate was not treated, and the other was sprayed with 2 mm thick ablation-resistant coating, and after air drying at room temperature for 7 days, relevant tests were carried out.

[0032] Example 4: (1) Epoxy-modified silicone resin was prepared; (2) 100 parts of epoxy-modified silicone resin, 20 parts of isocyanate group-modified siloxane, 10 parts of nano-silica aerogel, 10 parts of nano-titanium dioxide, 10 parts of nano-boron oxide, 0.8 parts of Mn-Ca catalyst, and 2.5 parts of KH570 were weighed according to the mass fraction to prepare an ablation-resistant coating primer base; (3) In the above-mentioned ablation-resistant coating primer base, 1 part of tetrabutyl titanate and a suitable amount of butyl acetate and No. 120 solvent oil compounded solvent (10% of ethyl acetate by volume) were added, mixed uniformly, sprayed on two aluminum alloy substrates, the spraying thickness was 100 μm, and after air drying at room temperature for 10 minutes, one aluminum alloy substrate was not treated, and the other was sprayed with 2 mm thick ablation-resistant coating, and after air drying at room temperature for 7 days, relevant tests were carried out.

[0033] Comparative Example 1: (1) 2 mm thick ablation-resistant coating was prepared on the aluminum alloy substrate, and after air drying at room temperature for 7 days, relevant tests were carried out.

[0034] Comparative Example 2: (1) Select the commercially available primer, according to the use of the base material preparation, spraying on two pieces of aluminum alloy substrate, spraying thickness is 100 μm, room temperature to 10 minutes after, one piece of aluminum alloy substrate is not treated, the other piece of spraying 2mm thick ablation resistant coating, room temperature to solidify 7 days, the relevant test is carried out.

[0035] Comparative example 3: (1) according to the mass fraction of 100 parts of commercially available epoxy modified silicone resin, 20 parts of isocyanate group modified siloxane, 10 parts of nano silica aerogel, 10 parts of nano titanium dioxide, 10 parts of nano boron oxide, 0.8 parts of Mn-Ca catalyst, 2.5 parts of KH570, the preparation of ablation resistant coating primer base material is obtained; (2) in the above ablation resistant coating primer base material, add 1 part of tetrabutyl titanate and appropriate amount of butyl acetate and 120 number of solvent oil compound solvent (volume fraction of ethyl acetate is 10%), mix evenly, spray on two pieces of aluminum alloy substrate, spraying thickness is 100 μm, room temperature to 10 minutes after 20 minutes, one piece of aluminum alloy substrate is not treated, the other piece of spraying 2mm thick ablation resistant coating, room temperature to solidify 7 days, the relevant test is carried out.

[0036] Comparative example 4: (1) preparation of epoxy modified silicone resin; (2) according to the mass fraction of 50 parts of epoxy modified silicone resin, 5 parts of isocyanate group modified siloxane, 0.8 parts of Mn-Ca catalyst, 1 part of KH570, the preparation of ablation resistant coating primer base material is obtained; (3) in the above ablation resistant coating primer base material, add 1 part of tetrabutyl titanate and appropriate amount of butyl acetate and 120 number of solvent oil compound solvent (volume fraction of ethyl acetate is 10%), mix evenly, spray on two pieces of aluminum alloy substrate, spraying thickness is 100 μm, room temperature to 10 minutes after, one piece of aluminum alloy substrate is not treated, the other piece of spraying 2mm thick ablation resistant coating, room temperature to solidify 7 days, the relevant test is carried out.

[0037] The sample performance test provided in the examples and comparative examples of the application is shown in table 1.

[0038] According to the data in Table 1, the special primer design, the self-made epoxy modified silicone resin and modified siloxane as the primer base glue, the compounding of functional fillers and additives can significantly improve the adhesion of the ablative-resistant coating and the substrate material, and improve the temperature resistance and density of the primer itself. As shown in Examples 2-4, increasing the thickness of the primer can significantly improve the peel strength; as shown in Comparative Example 4 and Comparative Example 1, adding the primer can improve the bonding strength of the ablative-resistant coating and the substrate material; as shown in Comparative Example 4 and Comparative Example 2, the temperature resistance of the primer prepared by the present application is significantly improved compared with the commercially available primer, and the density and room temperature thermal conductivity are significantly reduced; as shown in Comparative Example 4 and Comparative Example 3, the primer prepared by the present application has the best comprehensive performance under the recommended parameters. In summary, the ablative-resistant primer described in the present application can maintain low density and high efficient heat insulation performance, and has certain lightweight heat insulation performance under the premise of improving the adhesion of the ablative-resistant heat insulation coating, which can effectively reduce the surface density.

[0039] Table 1 Performance test results of samples prepared by Examples and Comparative Examples Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing an ablation-resistant coating primer, characterized in that, Includes the following steps: Preparation of epoxy-modified organosilicon resin; The epoxy-modified silicone resin is mixed evenly with lightweight nanofiller, modified siloxane, drier, and silane coupling agent to prepare an ablation-resistant coating primer base material. A curing agent and a diluent are added to the ablation-resistant coating primer base material and stirred until uniformly mixed to prepare the ablation-resistant coating primer.

2. The method as described in claim 1, characterized in that, The preparation steps of the epoxy-modified organosilicon resin include: dissolving the epoxy resin in xylene at twice its mass, and then adding organosilicon resin and coupling agent to allow for a complete reaction.

3. The method as described in claim 1, characterized in that, The mass ratio of the epoxy-modified silicone resin, lightweight nanofiller, modified siloxane, drier, and silane coupling agent is (60~120):(10~25):(20~50):(0.05~1.5):(2~3).

4. The method as described in claim 1 or 3, characterized in that, The lightweight nanofiller is one or more of nano-silica aerogel, nano-titanium dioxide, nano-boron carbide, boric acid, phosphorus oxide powder, and mica powder; the particle size of the lightweight nanofiller is 10~80nm. The modified siloxane is one or more of alkyl-modified siloxane, amino-modified siloxane, isocyanate-modified siloxane, and acrylic acid-modified siloxane, and the molecular weight of the modified siloxane is 5000-10000. The drying agent is one of Co-Ce, Co-Zr, and Mn-Ca drying agents; The silane coupling agent is one of KH550, KH560, KH570, KH792, and KH902.

5. The method as described in claim 1, characterized in that, The amount of curing agent used is 0.5% to 2% of the mass of the epoxy-modified silicone resin.

6. The method as described in claim 1 or 5, characterized in that, The curing agent is one or more of azo polymers, organotin, organozinc, organoaluminum, tetrabutyl titanate, and polyamide.

7. The method as described in claim 1, characterized in that, The diluent is one or more of ethyl acetate, butyl acetate, toluene, xylene, and No. 120 solvent oil.

8. A primer for ablation-resistant coatings, characterized in that, Prepared by the method described in any one of claims 1-7.

9. A coating, characterized in that, The ablation-resistant coating primer prepared by the method according to any one of claims 1-7 is made by the following steps: diluting the ablation-resistant coating primer with a diluent to the required viscosity, applying it to the surface of the substrate material with the required thickness by brushing, and obtaining the ablation-resistant coating primer coating after brushing.

10. The coating as claimed in claim 9, characterized in that, The diluent is one or more of methanol and n-pentanol, mixed with one or more of ethyl acetate, butyl acetate, toluene, xylene, petroleum ether, No. 60 solvent oil, and No. 120 solvent oil; the coating method is brushing or spraying; the thickness of the coating is 20~200um.

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