Low-infrared-emissivity coating for fluorinated silicone rubber wave-absorbing material and preparation method of low-infrared-emissivity coating

Abstract

The invention relates to the technical field of functional coatings, and provides a low-infrared-emissivity coating for a fluorinated silicone rubber wave-absorbing material and a preparation method thereof.The preparation method comprises the steps that firstly, silicone oil, an inhibitor, a flatting agent, a defoaming agent and a curing agent are sequentially added into a first mixing container, and a mixture A is obtained after primary dispersion stirring and uniform mixing; adding the aluminum powder, the dispersing agent, the silane coupling agent and the diluent into a second mixing container, carrying out secondary dispersing and stirring, and uniformly mixing to obtain a mixture B; and finally, mixing the mixture A and the mixture B according to the mass ratio of 1: (0.8-1.2), dispersing and stirring for three times, and uniformly mixing to obtain the low-infrared-emissivity coating for fluorinated silicone rubber. The prepared low-infrared-emissivity coating and fluorosilicone rubber are mutually diffused to form an excessive mutual transmission layer, and the binding force between the coating and the fluorosilicone rubber is enhanced, so that the use requirement of rubber as an elastomer is met, the application range of a fluorosilicone rubber wave-absorbing material is expanded, and the coating has both reflectivity and infrared stealth performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional coatings, and particularly relates to a low-infrared-emissivity coating for fluorosilicone rubber wave-absorbing materials and a preparation method thereof. BACKGROUND

[0002] In recent years, with the rapid development of modern infrared detection technology, it is particularly important to have advanced infrared stealth technology, especially in the field of aviation, which is directly related to the survival ability of the target. In order to enhance the environmental adaptability of various equipment in the application field, higher requirements are put forward for the infrared stealth technology. Low-emissivity infrared coating is the core functional material for realizing the infrared stealth of the target, and the radiation characteristics of the material in the infrared waveband (3~5 μm and 8~14 μm atmospheric window) are adjusted to realize the infrared stealth of the target.

[0003] As a high-performance synthetic rubber with both temperature resistance of silicone rubber and medium resistance of fluororubber, fluorosilicone rubber has irreplaceability in extreme environments. The temperature resistance range of fluorosilicone rubber is wide (about -60~230℃), the physical and mechanical properties are good, and the medium resistance performance is particularly outstanding. It has good resistance to fuel, hydraulic oil and lubricating oil commonly used in the field of aviation, and is often used as a sealing material and a wave-absorbing material in the field of aviation. With the development of aviation technology in recent years and the stringent requirements, the wave-absorbing patch still needs to meet certain infrared stealth performance on the basis of meeting the reflectivity, which requires the preparation of an infrared layer on the surface of the patch. In the fluorosilicone rubber patch, the surface energy of fluorosilicone rubber itself is low, which is poor in compatibility with commonly used resin coatings, and the rubber itself is an elastomer with high toughness. When it is bent at a large angle or used on the surface of a special-shaped part, the commonly used resin coating is prone to peeling, cracking and other phenomena, which limits the wide application of fluorosilicone rubber wave-absorbing patches with infrared layers in the field of wave-absorbing materials.

[0004] In view of this, the present application is proposed. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art and provide a low-infrared-emissivity coating for fluorosilicone rubber wave-absorbing materials and a preparation method thereof. The coating can be cured under medium and low temperature conditions and can form good bonding force with fluorosilicone rubber having low surface energy and high elastic properties.

[0006] The purpose of the present application is achieved by the following technical solutions: In a first aspect, the present application provides a low-infrared-emissivity coating for fluorosilicone rubber wave-absorbing materials, which comprises the following raw material components in terms of mass fraction: Silicone oil: 50~150 parts, curing agent: 5~20 parts, aluminum powder: 75~90 parts, auxiliary agent: 0.5~3.8 parts, diluent: 100 parts~350 parts; The auxiliary agent is composed of an inhibitor, a leveling agent, a dispersing agent, a defoaming agent and a silane coupling agent, and the mass ratio of the inhibitor, the leveling agent, the dispersing agent, the defoaming agent and the silane coupling agent in the auxiliary agent is 4:9:1:1:(5-15).

[0007] Further, the silicon oil is selected from a vinyl fluorosilicone oil, and the vinyl fluorosilicone oil is produced by Xinyuan Chemical (Shandong) Co., Ltd. The vinyl fluorosilicone oil includes but is not limited to any one or more of end vinyl fluorosilicone oil, side chain vinyl fluorosilicone oil and high vinyl fluorosilicone oil.

[0008] Further, the aluminum powder has a flaky micro-morphology and a particle size of about 20-60 μm.

[0009] Further, the curing agent is composed of hydrogen-containing fluorosilicone oil and platinum gold catalyst, and the mass ratio of the hydrogen-containing fluorosilicone oil and the platinum gold catalyst in the curing agent is (4.3-5.6):1; the hydrogen-containing fluorosilicone oil is produced by Xinyuan Chemical (Shandong) Co., Ltd., and the platinum gold catalyst is produced by Shanghai Platinum New Material Co., Ltd.

[0010] Further, the diluent is any one of n-octane, butyl acetate and n-decane.

[0011] Further, the inhibitor is 1-ethynyl-1 cyclohexanol produced by Shanghai Maikelin Biochemical Technology Co., Ltd., the leveling agent is fluorosilicone modified acrylic leveling agent produced by Hangzhou Keyin Chemical Co., Ltd., the dispersing agent is hexadecyl trimethyl ammonium bromide produced by Shanghai Maikelin Biochemical Technology Co., Ltd., the defoaming agent is fluorosilicone modified defoaming agent produced by Guozhong New Material Research Institute, and the silane coupling agent is vinyl triethoxysilane produced by Jiangxi Chen Guang New Material Co., Ltd.

[0012] In a second aspect, the present application provides a preparation method of fluorosilicone rubber facing low infrared emissivity coating, which comprises the following steps: S1. Silicon oil, inhibitor, leveling agent, defoaming agent and curing agent are sequentially added into a first mixing container, and after one-time dispersion stirring, a mixture A is obtained; S2. Aluminum powder, dispersing agent, silane coupling agent and diluent are added into a second mixing container, and after two-time dispersion stirring, a mixture B is obtained; S3. The mixture A and the mixture B are mixed in a mass ratio of 1:(0.8-1.2), and after three-time dispersion stirring, fluorosilicone rubber facing low infrared emissivity coating is obtained.

[0013] Further, the stirring speed of the one-time dispersion stirring in S1 is 150-500 r / min, and the stirring time is 8-15 min. The stirring speed of the secondary dispersion stirring in S2 is 300-500 r / min, and the stirring time is 3-8 min; The stirring speed of the tertiary dispersion stirring in S3 is 400-700 r / min, and the stirring time is 5-10 min.

[0014] In a third aspect, the application provides a low-infrared emissivity coating prepared from the low-infrared emissivity coating for fluorosilicone rubber wave-absorbing material, which is formed on the surface of a substrate by spraying or coating the low-infrared emissivity coating.

[0015] Further, the specific steps for forming the low-infrared emissivity coating are as follows: First, clean the surface of the substrate to be coated; then, spray or coat the low-infrared emissivity coating on the cleaned surface of the substrate to be coated, and cure at a curing temperature of 70-150 ℃ for 30-200 min; and finally obtain the low-infrared emissivity coating.

[0016] Compared with the prior art, the application has the following beneficial effects: 1. The low-infrared emissivity coating prepared from the low-infrared emissivity coating has strong bonding force and good toughness with the fluorosilicone rubber wave-absorbing material; on the one hand, the molecular structures of the two are similar, and the main chains are both siloxane bonds (-Si-O-), and the side chains are both trifluoropropyl groups (-CH2CH2CF3), which makes the two have excellent compatibility; on the other hand, the vinyl fluorosilicone oil has low viscosity and can easily penetrate into the micropores on the surface of the rubber, especially during the curing of the coating, the high temperature can intensify the movement of the molecular chains, promote the mutual diffusion of the coating and the fluorosilicone rubber, form a transition interlayer, and further enhance the bonding force between the two; this feature not only meets the use requirements of the rubber as an elastomer, but also expands the application range of the fluorosilicone rubber wave-absorbing material, and makes the material have both reflectivity and infrared stealth performance.

[0017] 2. The vinyl fluorosilicone oil, hydrogen-containing fluorosilicone oil and platinum gold catalyst are crosslinked together, and the core is based on the silicon hydrogen addition reaction, that is, the Si-H group on the hydrogen-containing fluorosilicone oil and the vinyl group (C=C) on the vinyl fluorosilicone oil are catalyzed by the platinum gold catalyst to generate a stable Si-CH2-CH2-Si crosslinking bond. Through the addition reaction between multiple functional groups, the polymer molecular chain is connected into a three-dimensional network elastomer. The fluorine-containing side chain does not directly participate in the core crosslinking reaction, but provides unique oil resistance, solvent resistance, high and low temperature resistance and other excellent properties for the finally cured fluorosilicone rubber. The curing system has the characteristics of no by-product and strong controllability.

[0018] 3. The curing rate can be controlled by adding an inhibitor, and the principle is as follows: Inhibitor: The 1-ethynyl-1-cyclohexanol molecule contains a hydroxyl group with three alkyl carbon atoms, which readily undergoes intramolecular dehydration under acidic conditions to form a conjugated olefin. This is the core of its inhibition mechanism. Furthermore, this inhibitor is highly volatile at high temperatures; it decomposes during high-temperature curing, thus eliminating its hindrance to curing and allowing the coating to cure smoothly. Typically, the evaporation rate of the inhibitor is mainly affected by temperature. Under certain conditions, the higher the temperature, the faster the evaporation rate, and the higher the coating curing efficiency. Its ability to control the curing rate allows it to adapt to different working conditions, thereby expanding its application range.

[0019] 4. The process used in this invention to prepare low emissivity infrared coatings is simple and conducive to mass production; all fillers and reagents used in the low emissivity infrared coatings are domestic brands and are low in cost. Attached Figure Description

[0020] The accompanying drawings are incorporated in and form part of this specification, and together with the description serve to explain the principles of the invention.

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart illustrating the preparation method of the low infrared emissivity coating for fluorosilicone rubber according to the present invention. Detailed Implementation

[0023] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples consistent with some aspects of the invention as detailed in the appended claims.

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the following description is provided in conjunction with the appendix. Figure 1 The present invention will be further described in detail with reference to the embodiments.

[0025] Example 1 This embodiment provides a low infrared emissivity coating for fluorosilicone rubber absorbing materials, comprising the following raw material components by weight: Silicone oil: 100 parts vinyl fluorosilicone oil; Curing agent: 8.57 parts platinum catalyst and hydrofluorosilicone oil (the mass ratio of platinum catalyst and hydrofluorosilicone oil is 5:1); Aluminum powder: 80 parts; Additives: composed of 0.52 parts 1-ethynyl-1-cyclohexanol inhibitor, 1.24 parts fluorosilicone modified acrylic leveling agent, 0.14 parts hexadecyltrimethylammonium bromide dispersant, 0.14 parts fluorosilicone modified defoamer, and 1.76 parts CG-151 silane coupling agent; Diluent: 124 parts n-octane.

[0026] A method for preparing a low infrared emissivity coating for fluorosilicone rubber microwave absorbing materials, comprising weighing the above-mentioned raw materials according to their corresponding mass parts, and including the following steps: S1. Silicone oil, inhibitor, leveling agent, defoamer and curing agent are added to the first mixing container in sequence. After one dispersion and stirring, mixture A is obtained after stirring for 15 minutes at a stirring speed of 150 r / min. S2. Add aluminum powder, dispersant, silane coupling agent and diluent to the second mixing container, and after two dispersion and stirring, stir for 8 minutes at a stirring speed of 300 r / min to obtain mixture B; S3. Mix mixture A and mixture B at a mass ratio of 1:0.8, disperse and stir three times, and stir for 10 minutes at a stirring speed of 400 r / min to obtain a low infrared emissivity coating for fluorosilicone rubber.

[0027] The test sample was prepared according to the following steps: Step 1: Wipe and clean the surface of the target object with alcohol or similar substances, mainly to remove dust, impurities, or oil stains.

[0028] Step 2: Spray / coat the prepared low-emissivity infrared coating onto the surface of the target object, and cure it at a curing temperature of 70°C for 200 minutes to obtain a low-emissivity coating.

[0029] The prepared samples were tested, and the test results are as follows: Example 2 This embodiment provides a low infrared emissivity coating for fluorosilicone rubber absorbing materials, according to quality... In parts, it includes the following raw material components: Silicone oil: 50 parts vinyl fluorosilicone oil; Curing agent: 5 parts platinum catalyst and hydrofluorosilicone oil (mass ratio of platinum catalyst to hydrofluorosilicone oil is 4.3:1); Aluminum powder: 75 parts; Additives: composed of 0.25 parts 1-ethynyl-1-cyclohexanol inhibitor, 0.57 parts fluorosilicone modified acrylic leveling agent, 0.06 parts hexadecyltrimethylammonium bromide dispersant, 0.06 parts fluorosilicone modified defoamer, and 0.83 parts CG-151 silane coupling agent; Diluent: 100 parts butyl acetate.

[0030] A method for preparing a low infrared emissivity coating for fluorosilicone rubber microwave absorbing materials, comprising weighing the above-mentioned raw materials according to their corresponding mass parts, and including the following steps: S1. Silicone oil, inhibitor, leveling agent, defoamer and curing agent are added to the first mixing container in sequence. After one dispersion and stirring, mixture A is obtained after stirring at a stirring speed of 350 r / min for 12 min. S2. Add aluminum powder, dispersant, silane coupling agent and diluent to the second mixing container, and after two dispersion and stirring, mix B is obtained after stirring at a stirring speed of 400 r / min for 6 min; S3. Mix mixture A and mixture B at a mass ratio of 1:1, disperse and stir three times, and stir for 8 minutes at a stirring speed of 500 r / min to obtain a low infrared emissivity coating for fluorosilicone rubber.

[0031] The test sample was prepared according to the following steps: Step 1: Wipe and clean the surface of the target object with alcohol or similar substances, mainly to remove dust, impurities, or oil stains.

[0032] Step 2: Spray / coat the prepared low-emissivity infrared coating onto the surface of the target object, and cure it at a curing temperature of 120℃ for 80 minutes to obtain a low-emissivity coating.

[0033] The prepared samples were tested, and the test results are as follows: Example 3 This embodiment provides a low infrared emissivity coating for fluorosilicone rubber absorbing materials, comprising the following raw material components by weight: Silicone oil: 150 parts vinyl fluorosilicone oil; Curing agent: 20 parts platinum catalyst and hydrofluorosilicone oil (the mass ratio of platinum catalyst and hydrofluorosilicone oil is 5.6:1); Aluminum powder: 90 parts; Additives: composed of 0.08 parts 1-ethynyl-1-cyclohexanol inhibitor, 0.165 parts fluorosilicone modified acrylic leveling agent, 0.018 parts hexadecyltrimethylammonium bromide dispersant, 0.018 parts fluorosilicone modified defoamer, and 0.223 parts CG-151 silane coupling agent; Diluent: 350 parts n-decane.

[0034] A method for preparing a low infrared emissivity coating for fluorosilicone rubber microwave absorbing materials, comprising weighing the above-mentioned raw materials according to their corresponding mass parts, and including the following steps: S1. Silicone oil, inhibitor, leveling agent, defoamer and curing agent are added to the first mixing container in sequence. After one dispersion and stirring, mixture A is obtained after stirring at a stirring speed of 500 r / min for 8 min. S2. Add aluminum powder, dispersant, silane coupling agent and diluent to the second mixing container, and after two dispersion and stirring, stir for 3 minutes at a stirring speed of 500 r / min to obtain mixture B; S3. Mix mixture A and mixture B at a mass ratio of 1:1.2, disperse and stir three times, and stir for 5 minutes at a stirring speed of 700 r / min to obtain a low infrared emissivity coating for fluorosilicone rubber.

[0035] The test sample was prepared according to the following steps: Step 1: Wipe and clean the surface of the target object with alcohol or similar substances, mainly to remove dust, impurities, or oil stains.

[0036] Step 2: Spray / coat the prepared low-emissivity infrared coating onto the surface of the target object, and cure it at a curing temperature of 120℃ for 80 minutes to obtain a low-emissivity coating.

[0037] The prepared samples were tested, and the test results are as follows: The samples prepared in the above three embodiments were tested, and the adhesion of the samples was 6.78 MPa, 4.32 MPa and 5.61 MPa, respectively. This shows that the low emissivity infrared coating provided by the present invention has strong adhesion to fluorosilicone rubber, which allows the absorbing material with fluorosilicone rubber as the substrate to be coated with a low emissivity infrared coating. This is beneficial to the better compatibility of fluorosilicone rubber absorbing patches with infrared stealth performance.

[0038] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention.

[0039] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A low infrared emissivity coating for fluorosilicone rubber microwave absorbing materials, characterized in that, Based on parts by weight, it includes the following raw material components: Silicone oil: 50~150 parts, curing agent: 5~20 parts, aluminum powder: 75~90 parts, additives: 0.5~3.8 parts, diluent: 100~350 parts; The additive is composed of inhibitor, leveling agent, dispersant, defoamer and silane coupling agent, and the mass ratio of inhibitor, leveling agent, dispersant, defoamer and silane coupling agent in the additive is 4:9:1:1:(5~15).

2. The low infrared emissivity coating for fluorosilicone rubber absorbing materials according to claim 1, characterized in that, The silicone oil used is vinyl fluorosilicone oil; The vinyl fluorosilicone oil includes, but is not limited to, any one or more of terminal vinyl fluorosilicone oil, side-chain vinyl fluorosilicone oil, and high vinyl fluorosilicone oil.

3. The low infrared emissivity coating for fluorosilicone rubber absorbing materials according to claim 1, characterized in that, The aluminum powder has a flake-like microstructure with a particle size of approximately 20-60 μm.

4. The low infrared emissivity coating for fluorosilicone rubber absorbing materials according to claim 1, characterized in that, The curing agent is composed of hydrofluoric silicone oil and platinum catalyst, and the mass ratio of hydrofluoric silicone oil to platinum catalyst in the curing agent is (4.3~5.6):

1.

5. The low infrared emissivity coating for fluorosilicone rubber absorbing materials according to claim 1, characterized in that, The diluent is any one of n-octane, butyl acetate, and n-decane.

6. The low infrared emissivity coating for fluorosilicone rubber absorbing materials according to claim 1, characterized in that, The inhibitor is 1-ethynyl-1-cyclohexanol; the leveling agent is a fluorosilicone-modified acrylic leveling agent; the dispersant is hexadecyltrimethylammonium bromide; the defoamer is a fluorosilicone-modified defoamer; and the silane coupling agent is vinyltriethoxysilane.

7. A method for preparing a low infrared emissivity coating for fluorosilicone rubber absorbing materials as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Silicone oil, inhibitor, leveling agent, defoamer and curing agent are added to the first mixing container in sequence, and after one dispersion and stirring, the mixture is mixed evenly to obtain mixture A; S2. Add aluminum powder, dispersant, silane coupling agent and diluent to the second mixing container, and mix evenly after two dispersion and stirring to obtain mixture B; S3. Mix mixture A and mixture B at a mass ratio of 1:(0.8~1.2), and after three dispersion and stirring, the mixture is uniformly mixed to obtain a low infrared emissivity coating for fluorosilicone rubber.

8. The method for preparing a low infrared emissivity coating for fluorosilicone rubber absorbing materials according to claim 7, characterized in that, The stirring speed for the single dispersion stirring described in S1 is 150~500 r / min, and the stirring time is 8~15 min. The stirring speed for the secondary dispersion stirring described in S2 is 300~500 r / min, and the stirring time is 3~8 min; The stirring speed for the three dispersion stirrings described in S3 is 400~700 r / min, and the stirring time is 5~10 min.

9. A low infrared emissivity coating prepared using the low infrared emissivity coating for fluorosilicone rubber absorbing materials as described in any one of claims 1-6, characterized in that, The low infrared emissivity coating is formed on the surface of a substrate by spraying or coating with low infrared emissivity paint.

10. The low infrared emissivity coating for fluorosilicone rubber absorbing materials according to claim 9, characterized in that, The specific steps for forming the low infrared emissivity coating are as follows: First, clean the surface of the substrate to be coated; then, spray or coat the low infrared emissivity coating onto the cleaned substrate surface and cure it at a curing temperature of 70~150℃ for 30~200min; finally, a low infrared emissivity coating is obtained.

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