Organosilicon foam additive as well as preparation method and application thereof

Abstract

The invention provides an organic silicon foam additive as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The organic silicon foam auxiliary agent has a structure as shown in a formula I. In the organic silicon foam auxiliary agent, R is selected from C3-C6 alkyl and C2-C6 alkyleneoxy ethylidene; r1 is selected from methyl or ethyl; n > = 0, x + y > = 1, and hydroxyl content > = 1%. The molecular structure of the silicon foaming agent is designed, and an epoxy ether chain segment, an alcohol ether chain segment and an alkoxy side group are introduced to a side chain of a silicon-oxygen chain segment and act together, so that the double effects of a foaming agent and an adhesion promoter can be achieved at the same time; the obtained foamed silicone rubber has the advantages of low specific gravity, uniform foam holes, good adhesive force, excellent dielectric property and the like. Formula I.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically to an organosilicon foam additive, its preparation method, and its application. Background Technology

[0002] The foaming agents used in silicone rubber foam are mostly compounds containing active hydroxyl groups, such as water, alcohols, and α,ω-dihydroxypolysiloxanes. These additives either have poor compatibility with silicone polymers, low boiling points leading to easy volatility and migration, or low compatibility with vinyl and hydrogen-containing silicone polymers. Furthermore, they exhibit high crosslinking density after foaming, resulting in high specific gravity and hardness of the silicone rubber foam. Some applications require silicone rubber foam to have ultra-low specific gravity, ultra-low hardness, and low dielectric constant, while also possessing a certain degree of adhesion to the substrate. Therefore, there is an urgent need to determine a silicone rubber foaming additive that has advantages such as simple synthesis method, environmental friendliness, and low cost, and can be applied to silicone rubber foam systems to achieve products with low specific gravity and hardness, higher foaming ratio, and lower dielectric loss. Summary of the Invention

[0003] The purpose of this invention is to address the aforementioned deficiencies of existing silicone foams by providing a novel silicone foaming agent. This foaming agent, when applied to silicone foam rubber systems, simultaneously functions as both a foaming agent and an adhesion promoter. The resulting silicone foam rubber exhibits advantages such as low specific gravity, uniform cell structure, good adhesion, and excellent dielectric properties.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A first aspect of the present invention provides an organosilicon foam additive having a structure as shown in Formula I: Formula I In Formula I, R is selected from C3-C6 alkylene groups and C3-C6 alkyloxyethylene groups; R 1 Selected from methyl or ethyl; n≥0, x+y≥1, hydroxyl content≥1%.

[0005] As an embodiment of the present invention, in the structure shown in Equation I, the following condition is satisfied: 1≤n+x+y≤8.

[0006] As an embodiment of the present invention, in the structure shown in Formula I, the following condition is satisfied: 0.2≤y / x≤2.

[0007] A second aspect of the present invention provides a method for preparing the organosilicon foam additive described in the first aspect of the present invention, comprising the following steps: Add a hydrosilylation catalyst to the hydrogen-containing silicone oil, heat to 70-110°C, add allyl glycidyl ether and vinyl alkoxysilane, and react for 1-5 hours; adjust the temperature to 80-110°C, add unsaturated alcohol, and react until no hydrosilylation residue remains to obtain the organosilicon foam additive.

[0008] As an embodiment of the present invention, the hydrosilylation catalyst includes at least one of isopropanol chloroplatinate and a cassette catalyst.

[0009] As an embodiment of the present invention, the amount of the hydrosilylation catalyst added is 0.04 to 0.06% of the mass of the hydrogen-containing silicone oil.

[0010] As an embodiment of the present invention, the R group in the structure of the organosilicon foam additive is selected from C3-C6 alkylene groups, and the unsaturated alcohol is a C3-C6 enol.

[0011] As an embodiment of the present invention, the R group in the structure of the organosilicon foam additive is selected from C2~C6 alkyloxyethylidene, and the unsaturated alcohol is an alcohol ether compound obtained by the addition of C2~C6 α-olefin and ethylene glycol.

[0012] As an embodiment of the present invention, the vinylalkoxysilane is vinyltrimethoxysilane or vinyltriethoxysilane.

[0013] A third aspect of the present invention provides the application of the silicone foam additive described in the first aspect of the present invention, wherein the silicone foam additive is used to prepare foamed silicone rubber.

[0014] As an embodiment of the present invention, the foamed silicone rubber comprises the following components in parts by weight: Component A: 100-150 parts base adhesive, 400-500 parts vinyl silicone oil, 100-120 parts organosilicon foam additive as described in the first aspect of this application, 250-300 parts inorganic filler, and 1-5 parts hydrosilylation catalyst; Component B: 100-150 parts base adhesive, 400-500 parts vinyl silicone oil, 60-80 parts hydrogen-containing silicone oil, 250-300 parts inorganic filler, 0.1-1 parts inhibitor, and 10-20 parts foam stabilizer.

[0015] Compared with the prior art, the beneficial effects of the present invention are: This invention designs the molecular structure of silicone foaming agents by introducing epoxy ether segments, alcohol ether segments, and alkoxy side groups onto the side chains of the silicon oxide segments. The three work together to simultaneously achieve the dual effects of a foaming agent and an adhesion promoter. The resulting foamed silicone rubber has advantages such as low specific gravity, uniform cell structure, good adhesion, and excellent dielectric properties. Detailed Implementation

[0016] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further describe the invention below. However, these embodiments do not limit the invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in this invention are conventional reagents, methods, and equipment in this technical field. Unless otherwise specified, all reagents and materials used in this invention are commercially available.

[0017] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0018] In this invention, numerical ranges are involved. Unless otherwise specified, the numerical ranges are considered continuous and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe features or characteristics, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0019] Unless otherwise specified, all reagents or instruments used in this invention are commercially available products.

[0020] In a first aspect, an embodiment of the present invention provides an organosilicon foam additive having a structure as shown in Formula I: Formula I In Formula I, R is selected from C3-C6 alkylene groups and C3-C6 alkyloxyethylene groups; R 1 Selected from methyl or ethyl; n≥0, x+y≥1, hydroxyl content≥1%.

[0021] In embodiments of the present invention, the hydroxyl content in the silicone foam additive can be obtained by testing using the ASTM D1957-86 (2001) method.

[0022] This invention designs the molecular structure of silicone-based foaming agents. The silicone foam additive of this invention uses a silicon-oxygen chain as the main chain, with epoxy-based ether segments, alcohol-based ether segments, and alkoxy-based silicon-containing side chains introduced onto the side chains of the silicon-oxygen chain. Specifically: the end groups of the alcohol-based ether side chains are active hydroxyl groups, which can participate in the foaming reaction and effectively reduce the specific gravity of the foamed silicone rubber; simultaneously, the epoxy groups in the epoxy-based ether side chains and the alkoxy groups in the alkoxy-based silicon-containing side chains have strong adhesion to the substrate, improving the adhesion of the foamed silicone rubber to substrates such as glass and metal, eliminating gap defects, avoiding charge accumulation and polarization at the interface, and preventing a surge in dielectric loss due to interface gaps; the silicon segments in the main chain and silicon-containing side chains help improve the compatibility of the silicone foam additive with the base adhesive, enhancing its dispersibility in the base adhesive, which not only improves foaming uniformity and the dielectric properties of the foamed silicone rubber, avoiding the risk of dielectric breakdown caused by local electric field concentration, but also avoids risks such as migration and precipitation.

[0023] Furthermore, the active hydroxyl groups of the alcohol ether side chains can form hydrogen bonds with the terminal epoxy groups of the epoxy ether segments, regulating the foaming rate and cell growth rhythm, avoiding defects such as large pore size, broken pores, or cell agglomeration caused by excessively rapid foaming, and forming closed cells in the foamed silicone rubber base. The dielectric constant of the gas in the closed cells is much lower than that of the base rubber. The alkoxy-containing silicon side chains can uniformly disperse the alcohol ether segments and epoxy ether segments in the base rubber, further improving the uniformity of cell distribution in the base rubber.

[0024] Therefore, introducing epoxy ether segments, alcohol ether segments, and alkoxy silicon-containing side chains onto the side chains of the silica-oxygen segments can simultaneously act as both a foaming agent and an adhesion promoter. The combined effect of these three components ensures that the foamed silicone rubber, both within the rubber itself and at the interface with the substrate, has no "weak points" in dielectric properties—neither large internal bubbles cause a decrease in dielectric breakdown strength, nor interface gaps lead to a surge in dielectric loss, thus achieving an overall improvement in dielectric performance. The resulting foamed silicone rubber possesses advantages such as low specific gravity, uniform cell structure, good adhesion, and low dielectric constant.

[0025] In some embodiments of the present invention, the structure shown in Formula I satisfies: 1≤n+x+y≤8. When n+x+y is within the above suitable range, the molecular weight of the organosilicon foam additive is moderate, and its low viscosity ensures uniform dispersion in the silicone rubber base. It also minimizes gas diffusion resistance, preventing insufficient foaming due to excessively long molecular chains (too high viscosity) or cell collapse due to excessively short chains (unstable structure), further reducing the specific gravity and dielectric constant of the foamed silicone rubber.

[0026] In some embodiments of the present invention, the structure shown in Formula I satisfies: 0.2 ≤ y / x ≤ 2. x represents the degree of polymerization of the silicon-oxygen backbone containing epoxy ether side chains, and y represents the degree of polymerization of the silicon-oxygen backbone with alkoxy-containing silicon side chains. The ratio of these two side chains within the aforementioned suitable range ensures uniform dispersion in the silicone rubber base, minimizes gas diffusion resistance, forms uniform and structurally complete closed cells, and improves the overall performance of the foamed silicone rubber.

[0027] A second aspect of the present invention provides a method for preparing the organosilicon foam additive described in the first aspect of the present invention, comprising the following steps: Add a hydrosilylation catalyst to the hydrogen-containing silicone oil, heat to 70-110°C, add allyl glycidyl ether and vinyl alkoxysilane, and react for 1-5 hours; adjust the temperature to 80-110°C, add unsaturated alcohol, and react until no hydrosilylation residue remains to obtain the organosilicon foam additive.

[0028] In this invention, during the reaction process, a portion of the reaction solution is extracted at fixed intervals (e.g., 10 min or 30 min) and placed in a liquid infrared spectrometer for analysis to monitor the content of silicon-hydrogen bonds in the reaction solution. The reaction is stopped when the infrared display shows no silicon-hydrogen bond residue, and the organosilicon foam additive is obtained.

[0029] In some embodiments of the present invention, the hydrogen-containing silicone oil is a linear hydrogen-containing silicone oil, and the general structural formula of the linear hydrogen-containing silicone oil is (CH3)3SiO—[Si(CH3)2O]. n —[SiH(CH3)O] x+y —Si(CH3)3. By reacting the side-chain monomers with the hydrogen silane bonds in the hydrogen-containing silicone oil, the above-mentioned epoxy ether segments, alcohol ether segments, and alkoxy silicon-containing side chains can be introduced into the main chain of the hydrogen-containing silicone oil.

[0030] Among them, the carbon-carbon double bond in allyl glycidyl ether can undergo hydrosilylation with hydrogen-containing silicone oil, and the epoxy ether segment can be covalently grafted onto the hydrogen-containing silicone oil; the carbon-carbon double bond in vinylalkoxysilane can undergo hydrosilylation with hydrogen-containing silicone oil, and the alkoxy silicon-containing side chain can be covalently grafted onto the hydrogen-containing silicone oil; the carbon-carbon double bond in unsaturated alcohol can undergo hydrosilylation with hydrogen-containing silicone oil, and the alcohol ether segment can be covalently grafted onto the hydrogen-containing silicone oil.

[0031] In some embodiments of the present invention, when R in the structural formula (Formula I) of the organosilicon foam additive is selected from C3 to C6 alkylene groups, the unsaturated alcohol is selected from enols with the corresponding number of carbon atoms. For example, when R is a C3 alkyl group (—C3H6—), the corresponding reactive monomer is allyl alcohol (structural formula CH2=CHCH2OH).

[0032] In some embodiments of the present invention, when R in the structural formula (Formula I) of the organosilicon foam additive is selected from C2-C6 alkyloxyethylene, the unsaturated alcohol is selected from an alcohol ether compound obtained by the addition of α-olefins with the corresponding number of carbon atoms to ethylene glycol. For example, when R is ethyleneoxyethylene (structural formula —(C2H4—O)—C2H4—), the corresponding reactant monomer is ethylene glycol monovinyl ether; when R is propyleneoxyethylene (structural formula —(C3H6—O)—C2H4—), the corresponding reactant monomer is ethylene glycol monoallyl ether.

[0033] In some embodiments of the present invention, when R 1 When methyl is selected, the corresponding monomer is vinyltrimethoxysilane; when R 1 When ethyl is selected, the corresponding reaction monomer is vinyltriethoxysilane.

[0034] In some embodiments of the present invention, the hydrosilylation catalyst includes at least one of isopropanol chloroplatinate and a cassette catalyst.

[0035] In some embodiments of the present invention, the amount of the hydrosilylation catalyst added is 0.04 to 0.06% of the mass of the hydrogen-containing silicone oil.

[0036] In a third aspect, the embodiments also provide the application of the organosilicon foam additive described in the first aspect of the invention, wherein the organosilicon foam additive is used to prepare foamed silicone rubber.

[0037] In some embodiments of the present invention, more specifically, the foamed silicone rubber comprises the following components in parts by weight: Component A: 100-150 parts base adhesive, 400-500 parts vinyl silicone oil, 100-120 parts organosilicon foam additive as described in the first aspect of the present invention, 250-300 parts inorganic filler, and 1-5 parts hydrosilylation catalyst. Component B: 100-150 parts base adhesive, 400-500 parts vinyl silicone oil, 60-80 parts hydrogen-containing silicone oil, 250-300 parts inorganic filler, 0.1-1 parts inhibitor, and 10-20 parts foam stabilizer.

[0038] In some embodiments of the present invention, the base adhesive for the foamed silicone rubber is not particularly limited; any silicone rubber base adhesive commonly used in the art can be used to prepare the foamed silicone rubber in the present invention. For example, the silicone oil used for the base adhesive can be a double-ended vinyl silicone oil containing fumed silica.

[0039] In some embodiments of the present invention, the vinyl silicone oil in the above-mentioned foamed silicone rubber contains carbon-carbon double bonds, which can undergo a curing and crosslinking reaction with a crosslinking agent (hydrogen-containing silicone oil) under catalytic and / or light irradiation conditions. The vinyl group will undergo an addition reaction with the Si-H bonds in the hydrogen-containing silicone oil to form stable C-Si covalent bonds, crosslinking the linear vinyl silicone oil molecules into a three-dimensional network structure. The present invention does not specifically limit the type of vinyl silicone oil; commonly used vinyl silicone oils in the art can be used to prepare foamed silicone rubber in the present invention. The viscosity of the vinyl silicone oil at 25°C is in the range of 1000~5000 cps. In order to further improve the spatial distribution of the crosslinked network structure, firmly fix the cell, and thus improve the hardness, reduce the dielectric constant, and improve the overall performance of the foamed silicone rubber, two or more vinyl silicone oils with different viscosities can be added for compounding. For example, a first vinyl silicone oil (viscosity of 1000 cps at 25°C) and a second vinyl silicone oil (viscosity of 5000 cps at 25°C) can be added.

[0040] In some embodiments of the present invention, inorganic fillers are used to maintain the mechanical strength of the foamed silicone rubber and improve its heat resistance. Commonly used thermally conductive inorganic fillers in the art can be used to prepare foamed silicone rubber in the present invention, such as, but not limited to, aluminum hydroxide.

[0041] In some embodiments of the present invention, in the above-mentioned foamed silicone rubber, the molecular backbone of the hydrogen-containing silicone oil is also a siloxane structure, with the core feature being that the side chains or end groups contain active Si-H bonds. Its function is "dual"—it acts as both a crosslinking agent and a source of foaming gas (dehydrogenation to produce H2). The Si-H bonds undergo hydrosilylation with the vinyl groups of the vinyl silicone oil, serving as a "bridge" for constructing the three-dimensional network structure. Under specific conditions (platinum catalyst, trace amounts of moisture / foaming aid, temperature triggering), the Si-H bonds of the hydrogen-containing silicone oil undergo dehydrogenation, decomposing to produce hydrogen gas. This hydrogen gas accumulates in the crosslinked network structure, driving the system to expand and form bubbles. Therefore, in the present invention, the "hydrosilylation catalyst and / or organosilicon foaming aid" and the "hydrogen-containing silicone oil" need to be dispersed in different components (i.e., component A and component B) for storage to prevent crosslinking and curing before use.

[0042] In some embodiments of the present invention, an inhibitor is also added to the foamed silicone rubber. The inhibitor can coordinate with the active sites of the catalyst, preventing cross-linking and curing before the components A and B are evenly mixed during the mixing process. This significantly extends the "pot life" of the rubber compound (i.e., the time it remains fluid after mixing, adjustable from a few minutes to several hours), ensuring that operators have sufficient time to complete the processing. Commonly used silicone rubber inhibitors in the art can be used in this invention; exemplarily, the inhibitors include, but are not limited to, alkynyl alcohol inhibitors.

[0043] In some embodiments of the present invention, to prevent cell migration to the silicone surface, a foam stabilizer is typically added to the foamed silicone rubber compound. Common foam stabilizers in the art can be used in the preparation of foamed silicone rubber in this invention, and no particular limitation is placed on the foam stabilizer. Exemplarily, the foam stabilizer includes, but is not limited to, at least one of polyether-modified silicone oil, fluorosilicone oil-based foam stabilizers, and fluorocarbon-based foam stabilizers.

[0044] The following are specific embodiments of the present invention.

[0045] Information on some of the raw materials used in the embodiments of the present invention is listed below. Unless otherwise specified, all raw materials are commercially available products or are prepared by conventional means in the art: Example 1 This embodiment provides an organosilicon foam additive, which is prepared by a method including the following steps: 342.52 g (1 mol) of hydrogen-containing silicone oil (CH3)3SiO[(CH3)(H)SiO]3Si(CH3)3 was added to a four-necked flask equipped with a thermometer, dropping funnel, mechanical stirrer, and condenser. The stirring was started, and the temperature was raised to 60 °C. 1.76 g of caster catalyst was added, and the mixture was stirred for 30 min. The temperature was raised to 90 °C, and a mixture of 114.14 g (1 mol) of allyl glycidyl ether and 148.24 g (1 mol) of vinyltrimethoxysilane was added dropwise over 30 min. After the addition was completed, the mixture was reacted for 2 h. 58.08 g (1 mol) of allyl alcohol was added dropwise, and the mixture was reacted at 90 °C for another 2 h until no silane residue was observed in the infrared spectrometer. The resulting organosilicon foam additive was designated ZJ-1, and its structural formula is shown in Formula I-1.

[0046] Formula I-1.

[0047] Example 2 This embodiment provides an organosilicon foam additive, which is prepared by a method including the following steps: 342.52 g of hydrogen-containing silicone oil (CH3)3SiO[(CH3)(H)SiO]3Si(CH3)3 was added to a four-necked flask equipped with a thermometer, dropping funnel, mechanical stirrer, and condenser. The stirring was started, and the temperature was raised to 60 °C. 1.95 g of caster catalyst was added, and the mixture was stirred for 30 min. The temperature was raised to 90 °C, and a mixture of 114.14 g (1 mol) allyl glycidyl ether and 190.31 g (1 mol) vinyltriethoxysilane was added dropwise over 30 min. After the addition was completed, the mixture was reacted for 2 h. 88.11 g (1 mol) ethylene glycol monovinyl ether was added dropwise. After the addition was completed, the mixture was reacted at 90 °C for another 2 h until no silane residue was observed in the infrared spectrometer. The resulting organosilicon foam additive was designated ZJ-2, and its structural formula is shown in Formula I-2.

[0048] Formula I-2.

[0049] Example 3 This embodiment provides an organosilicon foam additive, which is prepared by a method including the following steps: 342.52 g (1 mol) of hydrogen-containing silicone oil (CH3)3SiO[(CH3)(H)SiO]3Si(CH3)3 was added to a four-necked flask equipped with a thermometer, dropping funnel, mechanical stirrer, and condenser. The stirring was started, and the temperature was raised to 60°C. 1.88 g of Castells catalyst was added, and the mixture was stirred for 30 min. The temperature was raised to 90°C, and a mixture of 114.14 g (1 mol) of allyl glycidyl ether and 148.24 g (1 mol) of vinyltrimethoxysilane was added dropwise over 30 min. After the addition was completed, the mixture was reacted for 2.5 h. 102.13 g (1 mol) of ethylene glycol monoallyl ether was added dropwise. After the addition was completed, the mixture was reacted at 90°C for another 2 h until no silane residue was observed in the infrared spectrometer. The resulting organosilicon foam additive was designated ZJ-3, and its structural formula is shown in Formula I-3.

[0050] Formula I-3.

[0051] Example 4 This embodiment provides an organosilicon foam additive, which is prepared by a method including the following steps: 416.63 g (1 mol) of hydrogen-containing silicone oil (CH3)3SiO(CH2)2SiO[(CH3)(H)SiO]3Si(CH3)3 was added to a four-necked flask equipped with a thermometer, dropping funnel, mechanical stirrer, and condenser. The stirring was started, and the temperature was raised to 60 °C. 1.88 g of caster catalyst was added, and the mixture was stirred for 30 min. The temperature was raised to 90 °C, and a mixture of 114.14 g (1 mol) of allyl glycidyl ether and 148.24 g (1 mol) of vinyltrimethoxysilane was added dropwise over 30 min. After the addition was completed, the mixture was reacted for 2 h. 58.08 g (1 mol) of allyl alcohol was added dropwise, and the mixture was reacted at 90 °C for another 2 h until no silane residue was observed in the infrared spectrometer. The resulting organosilicon foam additive was designated ZJ-4, and its structural formula is shown in Formula I-4.

[0052] Formula I-4.

[0053] Examples 5-12, Comparative Examples 1-4 A series of silicone foam additives are provided, prepared according to the method of Example 1. Based on Example 1, by adjusting the "type of hydrogen-containing silicone oil" and / or the "type and amount of unsaturated alcohol" and / or the "type and amount of vinylalkoxysilane", silicone foam additives with the structure (Formula I) shown in Table 1 are prepared: Formula I.

[0054] Table 1 Structural parameters of Formula I Application examples Foamed silicone rubber was prepared using the organosilicon foam additives obtained in the above embodiments or comparative examples. The composition of the foamed silicone rubber is as follows: Component A: At room temperature (25±2℃), 146.0 parts by weight of the base adhesive (a double-ended vinyl silicone oil containing 30wt% fumed silica, with a viscosity of 5000 cps at 25℃), 67.3 parts by weight of vinyl silicone oil with a viscosity of 1000 cps at 25℃ (vinyl content 0.32wt%), 395.4 parts by weight of vinyl silicone oil with a viscosity of 5000 cps at 25℃ (vinyl content 0.16wt%), and 100 parts by weight of the silicone foam additive prepared in the above examples or comparative examples were mixed and dispersed for 15 min under a vacuum of -0.09 MPa and a rotation speed of 1500 rpm. 280.4 parts by weight of aluminum hydroxide were added in batches and dispersed for 30 min under a pressure of -0.09 MPa and a rotation speed of 1500 rpm. Finally, 4 parts by weight of the caster catalyst were added and dispersed for 10 min at 800 rpm. The mixture was then discharged and packaged according to the standard ASTM. The density of component A, as determined by test D792-20, is 1.15 g / cm³. 3 ; Component B: At room temperature (25±2℃), add 145.7 parts by weight of base adhesive (double-ended vinyl silicone oil containing 30wt% fumed silica, with a viscosity of 5000 cps at 25℃), 73.5 parts by weight of vinyl silicone oil (0.32wt% vinyl content) with a viscosity of 1000 cps at 25℃, and 400.9 parts by weight of vinyl silicone oil (0.16wt% vinyl content) with a viscosity of 5000 cps at 25℃, and then apply the mixture under -0.09MPa vacuum and 1500... Disperse at rpm for 30 min; add 280 parts by weight of aluminum hydroxide in batches, disperse at -0.09 MPa and 1500 rpm for 30 min, then add 0.4 parts by weight of the inhibitor tetramethyldivinyldisiloxane and 68 parts by weight of hydrogen-containing silicone oil (1.6 wt% hydrogen content) with a viscosity of 25 cps at 25°C, disperse at 600 rpm for 15 min; finally add 12 parts by weight of foam stabilizer DC193, disperse at 300 rpm for 15 min, discharge and package, and test according to the standard ASTM D792-20, the density of component B is 1.15 g / cm³. 3 ; After mixing components A and B in a 1:1 ratio, the mixture is applied to the surface of a glass substrate and then foamed and cross-linked cured at 23±2℃ for 1 hour to obtain foamed silicone rubber.

[0055] The properties of the prepared foamed silicone rubber were tested, and the relevant test standards and results are shown in Table 2: 1. Density (g / cm³) 3 ): The test shall be conducted in accordance with the test standard ASTM D792-20; 2. Closed-pore ratio (%): The test was conducted in accordance with the testing standard GB / T10799-2008. 3. Shore hardness: Test using a hardness tester; 4. Dielectric constant: Referring to GB / T 1409 "Recommended methods for measuring the permittivity and dielectric loss factor of electrical insulating materials at power frequency, audio frequency and high frequency (including meter wave wavelength)," fully cured samples were prepared in a laboratory environment with a thickness of 2 mm ± 0.1 mm. The area was cut according to the specific instrument requirements. The two surfaces of the sample in contact with the electrodes should be parallel and as flat and smooth as possible. The test environment was 23 ± 2℃ and 50 ± 5% humidity.

[0056] 5. Adhesion test: According to GB / T 7124 "Determination of Tensile Shear Strength of Adhesives", 3003 aluminum was used, with dimensions of 100mm ± 0.25mm in length, 25mm ± 0.25mm in width, and 0.2mm ± 0.1mm in thickness. The adhesive was mixed and bonded to the sample, with a bonding area of ​​12.5mm ± 0.25mm. Sample curing: Cured in a constant temperature and humidity chamber (25℃ / 50%RH) for 24 hours. A universal tensile testing machine was used, and tensile stress was applied at a speed of 5mm / min. The curve was recorded, and the maximum stress during failure was the failure load F (N). Dividing this load by the bonding area A (mm²) yielded the tensile shear strength δ (MPa): δ = F / A.

[0057] Table 2 The above results indicate that: This invention designs the molecular structure of silicone foaming agents by introducing epoxy ether segments, alcohol ether segments, and alkoxy side groups onto the side chains of the silicon oxide segments. The three work together to simultaneously achieve the dual effects of a foaming agent and an adhesion promoter. The resulting foamed silicone rubber has advantages such as low specific gravity, uniform cell structure, good adhesion, and excellent dielectric properties.

[0058] The density of the foamed silicone rubber with the addition of the organosilicon foam additive of the present invention is all above 0.5 g / cm³. 3 The following foamed silicone rubbers have a closed-cell rate of over 90% (indicating uniform cell size), a Shore hardness of 00 (low hardness), a dielectric constant of less than 1.8, and adhesion that meets the application requirements (greater than 0.1 MPa).

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An organosilicon foam additive, characterized in that, The organosilicon foam additive has the structure shown in Formula I: Formula I In Formula I, R is selected from C3-C6 alkylene groups and C2-C6 alkyloxyethylene groups; R 1 Selected from methyl or ethyl; n≥0, x+y≥1, hydroxyl content≥1%.

2. The organosilicon foam additive according to claim 1, characterized in that, In the structure shown in Equation I, the following condition is met: 1≤n+x+y≤8.

3. The organosilicon foam additive according to claim 1, characterized in that, In the structure shown in Equation I, the following condition is met: 0.2≤y / x≤2.

4. The method for preparing the organosilicon foam additive according to any one of claims 1 to 3, characterized in that, Includes the following steps: Add a hydrosilylation catalyst to the hydrogen-containing silicone oil, heat to 70-110°C, add allyl glycidyl ether and vinyl alkoxysilane, and react for 1-5 hours; adjust the temperature to 80-110°C, add unsaturated alcohol, and react until no hydrosilylation residue remains to obtain the organosilicon foam additive.

5. The method for preparing the organosilicon foam additive according to claim 4, characterized in that, The hydrosilylation catalyst includes at least one of isopropanol chloroplatinate and cassette catalyst; the amount of the hydrosilylation catalyst added is 0.04~0.06% of the mass of the hydrogen-containing silicone oil.

6. The method for preparing the organosilicon foam additive according to claim 4, characterized in that, In the structure of the organosilicon foam additive, the R group is selected from C3-C6 alkylene groups, and the unsaturated alcohol is a C3-C6 enol.

7. The method for preparing the organosilicon foam additive according to claim 4, characterized in that, In the structure of the organosilicon foam additive, the R group is selected from C2-C6 alkyloxyethylene, and the unsaturated alcohol is an alcohol ether compound obtained by the addition of C2-C6 α-olefin and ethylene glycol.

8. The method for preparing the organosilicon foam additive according to claim 4, characterized in that, The vinylalkoxysilane is vinyltrimethoxysilane or vinyltriethoxysilane.

9. The application of the organosilicon foam additive according to any one of claims 1 to 3, characterized in that, The organosilicon foam additive is used to prepare foamed silicone rubber.

10. The application of the organosilicon foam additive according to claim 9, characterized in that, The foamed silicone rubber comprises the following components in parts by weight: Component A: 100-150 parts base adhesive, 400-500 parts vinyl silicone oil, 100-120 parts organosilicon foam additive as described in any one of claims 1-3, 250-300 parts inorganic filler, and 1-5 parts hydrosilylation catalyst; Component B: 100-150 parts base adhesive, 400-500 parts vinyl silicone oil, 60-80 parts hydrogen-containing silicone oil, 250-300 parts inorganic filler, 0.1-1 parts inhibitor, and 10-20 parts foam stabilizer.

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