A polysiloxane-based thermal insulation composition, coating and preparation method thereof suitable for metal substrates

Abstract

The present invention belongs to the field of coatings, and specifically relates to a polysiloxane-based thermal insulation composition, coating and preparation method thereof suitable for metal substrates. The coating provided by the present invention is added with epoxy-modified polysiloxane resin, so that the prepared composition and the coating prepared by the composition have good thermal insulation performance, anti-aging performance, temperature resistance, solvent resistance and other properties. The composition provided by the present invention can be applied to the surface of metal materials, and can be used in aircraft and ship equipment, and has good application prospects.

Description

Technical Field

[0001] The invention belongs to the field of coatings, and in particular relates to a polysiloxane-based thermal insulation composition suitable for a metal substrate, a coating and a preparation method thereof. Background Art

[0002] The main types of coatings for metal surfaces of existing aircraft, ships, etc. include chlorinated rubber paint, epoxy paint, alkyd paint and polyurethane paint, which have some disadvantages that cannot be ignored, such as poor durability, solvent resistance and environmental protection. In addition to good solvent resistance and environmental protection, polysiloxane coatings also have the properties of corrosion resistance, drag reduction, easy cleaning and anti-aging. However, due to the poor durability and stability of polysiloxane coatings in special environments, especially high temperature environments, the application of polysiloxane coatings in the field of aircraft and ship coatings is limited.

[0003] In addition, existing coatings on metal surfaces such as aircraft and ships have problems with poor insulation and heat preservation performance. When upgrading or repairing old coatings, compatibility between new and old coatings may also become a problem, and it is necessary to ensure seamless integration of new coatings with existing systems. All of these put forward higher requirements for coatings on metal surfaces such as aircraft and ships.

[0004] CN114350256B provides a high temperature resistant and high reflectivity coating component and preparation method, as well as the coating and construction method thereof, which uses epoxy modified polysiloxane resin and high reflective coating powder as main components to prepare a coating with good high temperature resistance. Although the introduction of siloxane can improve the toughness of the coating to a certain extent, the characteristics of the epoxy resin itself determine that it still has certain brittleness problems, especially brittleness problems under low temperature or high load conditions, and although polysiloxane can improve weather resistance to a certain extent, the epoxy resin may still accelerate aging when exposed to harsh environmental conditions such as high altitude and ocean (such as strong ultraviolet rays or extreme temperatures). Summary of the invention

[0005] The present invention provides a polysiloxane-based thermal insulation composition, a coating and a preparation method thereof suitable for a metal substrate. The epoxy-modified polysiloxane resin and a polysiloxane-modified filler with a specific structure are prepared and mixed in a certain ratio to prepare the composition, so as to solve the problem that the existing metal surface composition has poor high temperature resistance, mechanical properties, thermal insulation properties, aging resistance and the like.

[0006] In a first aspect, a polysiloxane-based thermal insulation composition suitable for a metal substrate is provided, comprising: an epoxy-modified polysiloxane resin, a filler and a solvent, wherein the content of the modified polysiloxane accounts for 40wt% to 60wt% of the total weight of the composition.

[0007] Furthermore, the content of the filler accounts for 20wt%-40wt% of the total weight of the composition, and the content of the solvent accounts for 10wt%-20wt% of the total weight of the composition.

[0008] Furthermore, the filler is a polysiloxane modified filler, and the polysiloxane is a styrene-maleic acid copolymer modified polysiloxane.

[0009] Furthermore, the solvent is at least one of water and ethanol; these two solvents are environmentally friendly and can reduce pollution to the environment.

[0010] Furthermore, the epoxy-modified polysiloxane resin contains benzene rings and carboxyl side chains, and is a comb-like structure; the epoxy-modified polysiloxane resin also contains polysiloxane segments; the epoxy-modified polysiloxane resin also contains epoxy groups;

[0011] Since the benzene ring can absorb ultraviolet rays and reduce the damage of the resin by ultraviolet rays, the aging resistance of the epoxy-modified polysiloxane resin can be improved; due to the presence of the sparse structure and the presence of the carboxyl group, the epoxy-modified polysiloxane resin has a higher adhesion, even on the surface of a smoother metal substrate. Since the polysiloxane chain segment has good thermal oxidation resistance, the aging resistance of the epoxy-modified polysiloxane resin is further enhanced; due to the presence of the epoxy group, the epoxy-modified polysiloxane resin has excellent resistance to chemical reagents and can improve the solvent resistance of the resin; in addition, the presence of the carboxyl side chain also helps to improve the compatibility, reduce the phase separation problem of the coating, make the coating more uniform and stable, and easy to repair without causing interface problems.

[0012] In a second aspect, the present invention provides a method for preparing a polysiloxane-based thermal insulation composition suitable for a metal substrate, comprising:

[0013] The epoxy-modified polysiloxane resin, filler and solvent are uniformly mixed to obtain the product.

[0014] Furthermore, the epoxy-modified polysiloxane resin is obtained by reacting a hydroxyl-containing styrene derivative, maleic acid, hydroxy acrylate, silica sol, epoxy resin and tripropylene glycol diacrylate.

[0015] Furthermore, the preparation method of the epoxy-modified polysiloxane comprises:

[0016] Step 1, mixing a hydroxyl-containing styrene derivative, maleic acid and hydroxy acrylate, and then adding an initiator to carry out polymerization reaction to obtain a hydroxyl-containing styrene-maleic acid copolymer; the hydroxyl-containing styrene derivative, maleic acid and hydroxy acrylate are polymerized in the presence of an initiator to obtain a styrene-maleic acid copolymer, and a large number of hydroxyl groups are introduced into the prepared styrene-maleic acid copolymer through this step;

[0017] Step 2, mixing the organosilicon intermediate and the silica sol evenly, standing, adding the hydroxyl-containing styrene-maleic acid copolymer obtained in step 1 to react, and obtaining a styrene-maleic acid copolymer-modified polysiloxane; the introduced hydroxyl groups are cross-linked with the highly active silanol groups on the silica sol to introduce the styrene-maleic acid polymer into the polysiloxane polymer chain segment;

[0018] Step 3: adding epoxy resin and tripropylene glycol diacrylate to the styrene-maleic acid copolymer modified polysiloxane obtained in step 2, and heating the mixture under the protection of nitrogen to obtain the epoxy-modified polysiloxane resin.

[0019] Furthermore, the hydroxyl-containing styrene derivative in step 1 is selected from at least one of p-hydroxystyrene, 4-acetoxystyrene and 4-tert-butoxyacyloxystyrene; such substances are selected to facilitate the introduction of hydroxyl groups.

[0020] Furthermore, the hydroxy acrylate in step 1 is hydroxyethyl acrylate or hydroxypropyl acrylate; such substances are selected to facilitate the introduction of hydroxyl groups.

[0021] Furthermore, the organosilicon intermediate in step 2 is selected from at least one of dimethylcyclosiloxane mixed ring (DMC), hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5).

[0022] Furthermore, in step 1, the molar ratio of the hydroxyl-containing styrene derivative, maleic acid and hydroxy acrylate is (1-3): (1-2):1.

[0023] Furthermore, the reaction temperature in step 1 is 80-90° C. and the reaction time is 1-3 h.

[0024] Furthermore, in step 2, the mass ratio of the organosilicon to the silica sol is 5:(2-6).

[0025] Furthermore, the standing time in step 2 is 40-60° C. and the temperature is 0.5-1 h. The standing time should not be too long. If the standing time is too long, the silica sol will gel to a greater extent, which is not conducive to subsequent mixing and reaction.

[0026] Furthermore, the mass ratio of the hydroxyl-containing styrene-maleic acid copolymer added in step 2 to the organosilicon intermediate is (1-3):1.

[0027] Furthermore, the reaction temperature in step 2 is 70-85° C. and the reaction time is 1.5-2.5 h.

[0028] Furthermore, the mass ratio of the styrene-maleic acid copolymer modified polysiloxane, epoxy resin and tripropylene glycol diacrylate added in step 3 is (5-7):1:1.

[0029] Furthermore, the heating reaction in step 3 is carried out at a temperature of 70-90° C. and for a time of 1.5-2.5 h.

[0030] Furthermore, the initiator in step 1 is at least one of azobisisobutyronitrile and benzoyl peroxide.

[0031] Furthermore, the amount of the initiator added in step 1 is 4-8% of the total mass of the styrene derivative, maleic acid and hydroxy acrylate; the amount of the initiator added should not be less than 4%. When the amount of initiator is small, the polymerization rate is low, but at the same time the molecular weight of the polymer will be larger, and ultimately the molecular weight of the prepared epoxy-modified polysiloxane resin will be larger, which makes the viscosity lower.

[0032] Furthermore, the polysiloxane-modified filler is obtained by modifying the surface of the filler with polysiloxane.

[0033] Furthermore, the preparation method of the polysiloxane modified filler comprises:

[0034] Step 1, preparing polysiloxane;

[0035] Step 2: Add silane coupling agent, polysiloxane and water to the filler in sequence according to the mass ratio of filler: silane coupling agent: polysiloxane: water of 10: (0.5-2): (2.5-4): (15-30), heat to 50-80°C for reaction for 1-3 hours, and obtain a polysiloxane-modified filler.

[0036] Silane coupling agent can cross-link with organic and inorganic substances at the same time. After adding silane coupling agent, the filler contains active groups, which are more tightly combined with polysiloxane, which is beneficial to improve the structural stability of the filler and make the obtained filler not easy to be peeled off from polysiloxane under strong impact; in addition, the cross-linking reaction formed by silane coupling agent with filler and polysiloxane at the same time is beneficial to improve the toughness and other mechanical properties of the filler; the coating of polysiloxane on the surface of the filler is also beneficial to the high compatibility and wettability of the filler and epoxy-modified polysiloxane resin, which is beneficial to mixing and can improve the adhesion of the prepared coating on the metal substrate.

[0037] Furthermore, the filler is selected from at least one of wollastonite, mica powder and ceramic particles; this type of filler has good temperature resistance and can be better applied to harsh environments such as high altitude and deep sea.

[0038] Furthermore, the polysiloxane styrene-maleic acid copolymer modified polysiloxane in step 1 is prepared by:

[0039] Step 1, mixing a hydroxyl-containing styrene derivative, maleic acid and hydroxy acrylate, and then adding an initiator to carry out a polymerization reaction to obtain a hydroxyl-containing styrene-maleic acid copolymer;

[0040] Step 2: uniformly mix the organosilicon intermediate and the silica sol, let stand, add the hydroxyl-containing styrene-maleic acid copolymer obtained in step 1 to react, and obtain styrene-maleic acid copolymer modified polysiloxane.

[0041] Furthermore, in step 1, the molar ratio of the hydroxyl-containing styrene derivative, maleic acid and hydroxy acrylate is (1-3):(1-2):1.

[0042] Furthermore, the reaction temperature in step 1 is 80-90° C. and the reaction time is 1-3 h.

[0043] Furthermore, the mass ratio of the organosilicon to the silica sol in step 2 is 5:(2-6).

[0044] Furthermore, the standing time in step 2 is 40-60° C. and the temperature is 0.5-1 h.

[0045] Furthermore, the mass ratio of the hydroxyl-containing styrene-maleic acid copolymer added in step 2 to the organosilicon intermediate is (1-3):1.

[0046] Furthermore, the reaction temperature in step 2 is 70-85°C and the reaction time is 1.5-2.5h.

[0047] Furthermore, the initiator in step 1 is at least one of azobisisobutyronitrile and benzoyl peroxide.

[0048] Furthermore, the amount of the initiator added in step 1 is 4-8% of the total mass of the styrene derivative, maleic acid and hydroxy acrylate.

[0049] In a third aspect, the present invention provides a coating, which is prepared from the above-mentioned composition.

[0050] In a fourth aspect, the present invention provides a method for preparing a coating, comprising: coating the above-mentioned composition on the surface of a metal substrate and drying at room temperature for more than 1 week.

[0051] In a fifth aspect, the present invention provides an application of the above-mentioned composition in aircraft and ship equipment.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] The present invention provides a polysiloxane-based thermal insulation composition suitable for a metal substrate. Since the added epoxy-modified polysiloxane resin contains a polysiloxane segment, an epoxy group and a benzene ring, it has good aging resistance, corrosion resistance, weather resistance and other properties, so that the prepared composition has good high temperature resistance, aging resistance, corrosion resistance, solvent resistance and other properties;

[0054] And because the epoxy-modified polysiloxane resin contains both hydrophilic and hydrophobic groups, it has good compatibility and wettability in both organic and aqueous systems, which can greatly reduce the mixing time. When repairing the old coating, it can also effectively reduce the compatibility problem between the new and old coatings, and it can also have high adhesion to the metal substrate;

[0055] In addition, since silica aerogel is introduced into the epoxy-modified polysiloxane resin through a cross-linking reaction between silica sol, organosilicon and hydroxyl-containing styrene-maleic acid copolymer, the silica aerogel can be toughened. On the basis of improving the stability of the structure, the network structure formed by cross-linking and the rich pore structure of the silica aerogel make the composition have better thermal insulation performance;

[0056] In addition, due to the introduction of Si-O bonds, which have high bond energy and a wide range of bond angles, the prepared composition has excellent solvent resistance and high and low temperature resistance, and can better resist the impact of high-altitude and underwater harsh environments on the coating prepared using it, thereby being more conducive to improving the life of the prepared coating;

[0057] The preparation method of the composition provided by the invention is simple and easy to operate, convenient to apply and has good application prospects. DETAILED DESCRIPTION

[0058] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] The manufacturers of some reagents used in the examples and comparative examples of the present invention are shown in the table below; other reagents whose manufacturers are not provided are all common chemical reagents.

[0060] Serial number Reagents factory 1 Silane coupling agent Nanjing Shuguang Chemical Group 2 Silicone intermediates Shandong Dongyue Silicone Materials Co., Ltd. 3 Silica Sol Zhejiang Yuda Chemical Co., Ltd.

[0061] Example 1

[0062] 1. Preparation of epoxy-modified polysiloxane

[0063] Step 1, p-hydroxystyrene, maleic acid and hydroxyethyl acrylate are mixed in a molar ratio of 2:1:1, and then 4% of the total mass of p-hydroxystyrene, maleic acid and hydroxyethyl acrylate is added with azobisisobutyronitrile to react at 80° C. for 2 hours to obtain a hydroxyl-containing styrene-maleic acid copolymer;

[0064] Step 2, DMC and silica sol are mixed evenly at a mass ratio of 5:2, and the mixture is allowed to stand at 50°C for 0.5h. The hydroxyl-containing styrene-maleic acid copolymer obtained in step 1 is added to DMC at a mass ratio of hydroxyl-containing styrene-maleic acid copolymer to DMC of 2:1, and the mixture is reacted at 75°C for 2h to obtain styrene-maleic acid copolymer-modified polysiloxane;

[0065] Step 3: Add epoxy resin and tripropylene glycol diacrylate to the styrene-maleic acid copolymer modified polysiloxane obtained in step 2 at a mass ratio of 6:1:1 of styrene-maleic acid copolymer modified polysiloxane, epoxy resin and tripropylene glycol diacrylate; heat to 80° C. under nitrogen protection for 2 hours to obtain the epoxy-modified polysiloxane resin.

[0066] 2. Preparation of polysiloxane modified fillers

[0067] Vinyl triethoxysilane, styrene-maleic acid copolymer modified polysiloxane prepared in step 2 and deionized water were added to wollastonite in sequence at a mass ratio of wollastonite: vinyl triethoxysilane: styrene-maleic acid copolymer modified polysiloxane prepared in step 2: deionized water of 10:1:4:20, and the mixture was heated to 60°C for reaction for 2 hours to obtain a polysiloxane-modified filler.

[0068] 3. Preparation of the composition

[0069] 55 parts of the epoxy-modified polysiloxane resin, 30 parts of the polysiloxane-modified filler, and 15 parts of deionized water were mixed evenly to obtain the composition.

[0070] 4. Preparation of coating

[0071] The above composition is applied to the surface of a metal substrate and dried at room temperature for 1 week to obtain the coating, which is then subjected to a performance test.

[0072] Example 2

[0073] 1. Preparation of epoxy-modified polysiloxane resin

[0074] Step 1, 4-acetoxystyrene, maleic acid and hydroxypropyl acrylate are mixed at a molar ratio of 3:2:1, and then benzoyl peroxide is added at 6% of the total mass of 4-acetoxystyrene, maleic acid and hydroxypropyl acrylate to react at 90° C. for 1 hour to obtain a hydroxyl-containing styrene-maleic acid copolymer;

[0075] Step 2, D3 and silica sol are mixed evenly at a mass ratio of 5:4, and the mixture is allowed to stand at 60°C for 1 hour. The hydroxyl-containing styrene-maleic acid copolymer obtained in step 1 is added to D3 at a mass ratio of 3:1 of the hydroxyl-containing styrene-maleic acid copolymer to D3, and the mixture is reacted at 70°C for 2.5 hours to obtain a styrene-maleic acid copolymer-modified polysiloxane;

[0076] Step 3: Add epoxy resin and tripropylene glycol diacrylate to the styrene-maleic acid copolymer modified polysiloxane obtained in step 2 at a mass ratio of 5:1:1 of styrene-maleic acid copolymer modified polysiloxane, epoxy resin and tripropylene glycol diacrylate; heat to 70° C. under nitrogen protection and react for 2.5 hours to obtain the epoxy-modified polysiloxane resin.

[0077] 2. Preparation of polysiloxane modified fillers

[0078] Vinyltrimethoxysilane, styrene-maleic acid copolymer modified polysiloxane prepared in step 2 and deionized water were added to the ceramic particles in sequence at a mass ratio of 10: 2: 2.5: 15, and the mixture was heated to 50°C for reaction for 3 hours to obtain a polysiloxane-modified filler.

[0079] 3. Preparation of the composition

[0080] 60 parts of the epoxy-modified polysiloxane resin, 20 parts of the polysiloxane-modified filler and 20 parts of ethanol were mixed evenly to obtain the composition.

[0081] 4. Preparation of coating

[0082] The above composition is applied to the surface of a metal substrate and dried at room temperature for 1 week to obtain the coating, which is then subjected to a performance test.

[0083] Example 3

[0084] 1. Preparation of epoxy-modified polysiloxane resin

[0085] Step 1, 4-tert-butoxyacyloxystyrene, maleic acid and hydroxyethyl acrylate are mixed in a molar ratio of 1:1:1, and then 8% of the total mass of 4-tert-butoxyacyloxystyrene, maleic acid and hydroxyethyl acrylate is added with azobisisobutyronitrile, and the mixture is reacted at 85° C. for 3 hours to obtain a hydroxyl-containing styrene-maleic acid copolymer;

[0086] Step 2, D4 and silica sol are mixed evenly at a mass ratio of 5:6, and the mixture is allowed to stand at 40°C for 1 hour. The hydroxyl-containing styrene-maleic acid copolymer obtained in step 1 is added to D4 at a mass ratio of hydroxyl-containing styrene-maleic acid copolymer to D4 of 1:1, and the mixture is reacted at 85°C for 1.5 hours to obtain styrene-maleic acid copolymer-modified polysiloxane;

[0087] Step 3: adding epoxy resin and tripropylene glycol diacrylate to the styrene-maleic acid copolymer modified polysiloxane obtained in step 2 at a mass ratio of 7:1:1 of styrene-maleic acid copolymer modified polysiloxane, epoxy resin and tripropylene glycol diacrylate; heating to 90° C. under nitrogen protection for reaction for 2 hours to obtain the epoxy-modified polysiloxane resin.

[0088] 2. Preparation of polysiloxane modified filler:

[0089] According to the mass ratio of mica powder: 3-aminopropyl triethoxysilane: styrene-maleic acid copolymer modified polysiloxane prepared in step 2: water of 10:0.5:3:30, 3-aminopropyl triethoxysilane, styrene-maleic acid copolymer modified polysiloxane prepared in step 2 and deionized water are added to the mica powder in sequence, and the mixture is heated to 80°C for reaction for 1 hour to obtain a polysiloxane-modified filler.

[0090] 3. Preparation of the composition

[0091] 40 parts of the epoxy-modified polysiloxane resin, 40 parts of the polysiloxane-modified filler and 20 parts of water are mixed evenly to obtain the composition.

[0092] 4. Preparation of coating

[0093] The above composition is applied to the surface of a metal substrate and dried at room temperature for 1 week to obtain the coating, which is then subjected to a performance test.

[0094] Example 4

[0095] 1. Preparation of epoxy-modified polysiloxane resin

[0096] Step 1, p-hydroxystyrene, maleic acid and hydroxyethyl acrylate are mixed in a molar ratio of 2:1:1, and then 4% of the total mass of p-hydroxystyrene, maleic acid and hydroxyethyl acrylate is added with azobisisobutyronitrile to react at 80° C. for 2 hours to obtain a hydroxyl-containing styrene-maleic acid copolymer;

[0097] Step 2, DMC and silica sol are mixed evenly at a mass ratio of 5:2, and the mixture is allowed to stand at 50°C for 0.5h, and the hydroxyl-containing styrene-maleic acid copolymer obtained in step 1 is added to DMC at a mass ratio of hydroxyl-containing styrene-maleic acid copolymer to DMC of 2:1, and the mixture is reacted at 75°C for 2h to obtain styrene-maleic acid copolymer-modified polysiloxane;

[0098] Step 3: Add epoxy resin and tripropylene glycol diacrylate to the styrene-maleic acid copolymer modified polysiloxane obtained in step 2 at a mass ratio of 6:1:1 of styrene-maleic acid copolymer modified polysiloxane, epoxy resin and tripropylene glycol diacrylate; heat to 80° C. under nitrogen protection for 2 hours to obtain the epoxy-modified polysiloxane resin.

[0099] 2. Preparation of the composition

[0100] 55 parts of the epoxy-modified polysiloxane resin, 30 parts of wollastonite and 15 parts of water were mixed evenly to obtain the composition.

[0101] 3. Preparation of coating

[0102] The above composition is applied to the surface of a metal substrate and dried at room temperature for 1 week to obtain the coating, which is then subjected to a performance test.

[0103] Comparative Example 1

[0104] 1. Preparation of epoxy-modified polysiloxane resin

[0105] Step 1, p-hydroxystyrene, maleic acid and hydroxyethyl acrylate are mixed in a molar ratio of 2:1:1, and then 4% of the total mass of p-hydroxystyrene, maleic acid and hydroxyethyl acrylate is added with azobisisobutyronitrile to react at 80° C. for 2 hours to obtain a hydroxyl-containing styrene-maleic acid copolymer;

[0106] Step 2, adding the hydroxyl-containing styrene-maleic acid copolymer obtained in step 1 to DMC at a mass ratio of hydroxyl-containing styrene-maleic acid copolymer to DMC of 2:1, and reacting at 75° C. for 2 hours to obtain a styrene-maleic acid copolymer-modified polysiloxane;

[0107] Step 3: Add epoxy resin and tripropylene glycol diacrylate to the styrene-maleic acid copolymer modified polysiloxane obtained in step 2 at a mass ratio of 6:1:1 of styrene-maleic acid copolymer modified polysiloxane, epoxy resin and tripropylene glycol diacrylate; heat to 80° C. under nitrogen protection for 2 hours to obtain the epoxy-modified polysiloxane resin.

[0108] 2. Preparation of polysiloxane modified fillers

[0109] The preparation method of the polysiloxane modified filler is the same as that in Example 1.

[0110] 3. Preparation of the composition

[0111] The preparation of the composition is the same as in Example 1.

[0112] 4. Preparation of coating

[0113] The preparation of the coating is the same as in Example 1.

[0114] Comparative Example 2

[0115] 1. Preparation of epoxy-modified polysiloxane resin

[0116] Step 1, mixing styrene, maleic acid and ethyl acrylate in a molar ratio of 2:1:1, then adding azobisisobutyronitrile in an amount of initiator of 4% of the total mass of styrene, maleic acid and ethyl acrylate, and reacting at 80° C. for 2 hours to obtain a styrene-maleic acid copolymer;

[0117] Step 2, DMC and silica sol are uniformly mixed at a mass ratio of 5:2, and the mixture is allowed to stand at 50°C for 0.5h. The styrene-maleic acid copolymer obtained in step 1 is added to DMC at a mass ratio of styrene-maleic acid copolymer to DMC of 2:1, and the mixture is reacted at 75°C for 2h to obtain styrene-maleic acid copolymer-modified polysiloxane;

[0118] Step 3: Add epoxy resin and tripropylene glycol diacrylate to the styrene-maleic acid copolymer modified polysiloxane obtained in step 2 at a mass ratio of 6:1:1 of styrene-maleic acid copolymer modified polysiloxane, epoxy resin and tripropylene glycol diacrylate; heat to 80° C. under nitrogen protection for 2 hours to obtain the epoxy-modified polysiloxane resin.

[0119] 2. Preparation of polysiloxane modified fillers

[0120] The preparation method of the polysiloxane modified filler is the same as that in Example 1.

[0121] 3. Preparation of the composition

[0122] The preparation of the composition is the same as in Example 1.

[0123] 4. Preparation of coating

[0124] The preparation of the coating is the same as in Example 1.

[0125] Comparative Example 3

[0126] 1. Preparation of epoxy-modified polysiloxane resin

[0127] The preparation method of epoxy-modified polysiloxane resin is the same as that in Example 1.

[0128] 2. Preparation of polysiloxane modified fillers

[0129] Polysiloxane and deionized water were added to wollastonite in sequence at a mass ratio of wollastonite: polysiloxane: deionized water of 10:4:20, and the mixture was heated to 60°C for reaction for 2 hours to obtain a polysiloxane-modified filler; the polysiloxane was a styrene-maleic acid copolymer-modified polysiloxane, and its preparation method was the same as that in Example 1.

[0130] 3. Preparation of the composition

[0131] The preparation method of the composition is the same as that in Example 1.

[0132] 4. Preparation of coating

[0133] The preparation method of the coating is the same as that in Example 1.

[0134] Performance Testing

[0135] The performance test methods and results are shown in Table 1 and Table 2. Among them:

[0136] 1. The test of impact resistance (deformation 3±0.3mm, 5 / 8”, 134in-1b) refers to AAMA2605-17A, ASTMD2794-93 (2019);

[0137] 2. The hydrochloric acid resistance and alkali resistance test method refer to GB / T9274-1988, and the salt spray resistance (3000h) test method refer to GB / T1865-2007;

[0138] 3. The test method for detergent resistance (3%, 72h) refers to AAMA2605-17A and ASTM D2244-16; the water and oil contact angles are tested in accordance with ASTM D7334-08 (2013);

[0139] 4. The performance of resistance to artificial weathering (3000h) is tested in accordance with GB / T1865-2009, and the cyclic aging test (25 times) is tested in accordance with GB / T1766;

[0140] 5. The hardness test is carried out in accordance with GB / T6739-2006, and the bending test is carried out in accordance with GB / T6742-2007;

[0141] 6. The adhesion (pull-off method) test method shall refer to GB / T5210-2006;

[0142] 7. The test method for moisture and heat resistance (3000h) shall refer to GB / T174-02007, and the test method for moisture and cold cycle resistance (12 times) shall refer to JG / T25-1999;

[0143] 8.The thermal conductivity is tested in accordance with GB10295-2008.

[0144] Table 1

[0145] Impact resistance (deformation 3±0.3mm, 5 / 8”, 134in-1b) Artificial weathering resistance (5000h) Hardness ≥ Bending test ≤ Adhesion (pull-off method) / Mpa Cyclic aging test (25 times) Resistance to wet and cold cycles (15 times) Example 1 No peeling No rust, no blistering, no shedding 2H Level 1 8.1 Powdering ≤ Level 2, no rust, no blistering, no falling off, no cracking No abnormality Example 2 No peeling No rust, no blistering, no shedding 2H Level 1 7.9 Powdering ≤ Level 2, no rust, no blistering, no falling off, no cracking No abnormality Example 3 No peeling No rust, no blistering, no shedding 2H Level 1 7.8 Powdering ≤ Level 2, no rust, no blistering, no falling off, no cracking No abnormality Example 4 No peeling No rust, no blistering, no shedding 3H Level 1 7.2 Powdering ≤ Level 2, no rust, slight blistering, no falling off, no cracking No abnormality Comparative Example 1 No peeling No rust, no blistering 2H Level 1 8.0 Powdering ≤ Level 2, no rust, blistering, or cracking No abnormality Comparative Example 2 Slight peeling No rust, no blistering, slight peeling 2H Level 1 5.1 Powdering ≤ Level 2, no rust, no blistering, slight shedding, no cracking Slight shedding Comparative Example 3 No peeling No rust, slight blistering, no peeling 2H Level 1 6.9 Powdering ≤ Level 2, no rust, no blistering, no falling off, no cracking No abnormality

[0146] Table 2

[0147] Acid resistance Alkali resistance Cleaning agent resistance (3%, 100h) Water contact angle Oil contact angle Salt spray resistance (3000h) Cyclic aging test (25 times) Resistance to wet and cold cycles (12 times) Thermal conductivity (W / (m·K)) Example 1 600h no abnormality 480h no abnormality No peeling of coating and no obvious changes in appearance 125.7° 112.3° No rust, no blistering, no shedding Powdering ≤ Level 2, no rust, no blistering, no falling off, no cracking No abnormality 0.051 Example 2 600 h no abnormality 480h no abnormality No peeling of coating and no obvious changes in appearance 120.8 110.7 No rust, no blistering, no shedding Powdering ≤ Level 2, no rust, no blistering, no falling off, no cracking No abnormality 0.050 Example 3 600h no abnormality 480h no abnormality No peeling of coating and no obvious changes in appearance 121.7 111.6 No rust, no blistering, no shedding Powdering ≤ Level 2, no rust, no blistering, no falling off, no cracking No abnormality 0.048 Example 4 600h no abnormality 480h no abnormality Slight peeling of coating 110.5 101.6 No rust, no blistering, no shedding Powdering ≤ Level 2, no rust, no blistering, no falling off, no cracking No abnormality 0.061 Comparative Example 1 600h no abnormality 480h no abnormality No peeling of coating and no obvious changes in appearance 123.5 111.3 No rust, no blistering, no shedding Powdering ≤ Level 2, no rust, no blistering, no falling off, no cracking No abnormality 0.085 Comparative Example 2 600h no abnormality 480h no abnormality The coating peels off 120.6 109.8 No rust, slight blistering, no peeling Powdering ≤ Level 2, no rust, no blistering, no falling off, no cracking No abnormality 0.057 Comparative Example 3 600h no abnormality 480h no abnormality No peeling of coating and no obvious changes in appearance 118.7 107.9 No rust, no blistering, no shedding Powdering ≤ Level 2, no rust, no blistering, no shedding, slight cracking No abnormality 0.059

[0148] It can be seen from the above test results that the coating prepared by the composition provided by the method of the present invention has strong adhesion when used on metal surfaces; in addition, the prepared coating also has excellent temperature resistance, aging resistance, durability, solvent resistance, weather resistance and acid and alkali resistance, and also has good mechanical properties and thermal insulation properties. It can be well applied to special environments such as air and underwater, and has the potential to be used as a coating in the fields of aircraft and ships, and has good application prospects.

Claims

1. A polysiloxane-based thermal insulation composition suitable for metal surfaces, characterized in that: Comprising: epoxy-modified polysiloxane, filler and solvent, wherein the content of the epoxy-modified polysiloxane accounts for 40wt% to 60wt% of the total weight of the composition; The filler is a polysiloxane modified filler, and the polysiloxane is a styrene-maleic acid copolymer modified polysiloxane; The preparation method of the epoxy-modified polysiloxane comprises: Step 1, mixing a hydroxyl-containing styrene derivative, maleic acid and hydroxy acrylate, and then adding an initiator to carry out a polymerization reaction to obtain a hydroxyl-containing styrene-maleic acid copolymer; Step 2, mixing the organosilicon intermediate and the silica sol evenly, allowing the mixture to stand, and adding the hydroxyl-containing styrene-maleic acid copolymer obtained in step 1 to react to obtain a styrene-maleic acid copolymer-modified polysiloxane; Step 3: adding epoxy resin and tripropylene glycol diacrylate to the styrene-maleic acid copolymer modified polysiloxane obtained in step 2, and heating the mixture under the protection of nitrogen to obtain the epoxy modified polysiloxane.

2. The composition according to claim 1, characterized in that The hydroxy acrylate in step 1 is hydroxyethyl acrylate or hydroxypropyl acrylate.

3. The composition according to claim 1, characterized in that The content of the filler accounts for 20wt%-40wt% of the total weight of the composition, and the content of the solvent accounts for 10wt%-20wt% of the total weight of the composition.

4. The composition according to claim 1, characterized in that The filler is selected from at least one of wollastonite, mica powder and ceramic particles.

5. A method for preparing the composition according to any one of claims 1 to 4, characterized in that: include: The epoxy-modified polysiloxane resin, filler and solvent are uniformly mixed to obtain the product.

6. The method for preparing the composition according to claim 5, characterized in that: The epoxy-modified polysiloxane is obtained by reacting a hydroxyl-containing styrene derivative, maleic acid, hydroxy acrylate, silica sol, epoxy resin and tripropylene glycol diacrylate.

7. A method for preparing a polysiloxane-based coating suitable for a metal substrate, characterized in that: include: The composition according to any one of claims 1 to 4 is applied to the surface of a metal substrate and dried at room temperature for 1 week to obtain the product.

8. Use of the composition according to any one of claims 1 to 4 in aircraft and ship equipment.