A branched vinylphenyl polysiloxane and a method for preparing the same

Abstract

This invention discloses a branched vinylphenyl polysiloxane and its preparation method, comprising the following steps: mixing vinyl difunctional chain silane monomers, phenyl difunctional chain silane monomers, alkyl difunctional chain silane monomers, a solid acid catalyst, and acetic acid in a certain proportion, and performing a reflux reaction; filtering out the solid acid catalyst by cooling to obtain a first filtrate, and distilling it at atmospheric pressure to obtain a polysiloxane precursor; adding a trifunctional chain silane monomer, a capping agent, acetic acid, and a solid acid catalyst to the polysiloxane precursor, and reacting; filtering out the solid acid catalyst to obtain a second filtrate, and distilling it at atmospheric pressure to obtain a branched vinylphenyl polysiloxane with a vinyl content of 1.0~3.0% and a silanol content ≤0.1%. It can be used for surface modification of fillers in addition silicone rubber systems to improve the mechanical properties and system compatibility of materials, and solve the problems of few modified active sites and weak interfacial forces, as well as the problem that high silanol content affects the curing and adhesion of addition systems.

Description

Technical Field

[0001] This invention relates to the field of polymer compound technology, and in particular to a branched vinylphenyl polysiloxane and its preparation method. Background Technology

[0002] Addition-cure silicone rubber is widely used in aerospace thermal protection materials, but the interfacial matching problem between its inorganic filler and organic matrix has always constrained the improvement of material performance. Traditional fillers have insufficient surface modification active sites, making it difficult to form stable chemical bonds with the silicone rubber matrix. The interfacial bonding force is weak, and under thermal shock and mechanical loads, phenomena such as interfacial debonding and stress concentration are prone to occur, leading to a decline in the mechanical properties of the composite material. At the same time, the high content of silanol on the filler surface not only easily causes particle agglomeration and uneven dispersion, but also interferes with platinum-catalyzed addition reactions, affecting the degree of curing and adhesion of the system, thus limiting the application of the material in high-strength and high-ablation-resistance scenarios.

[0003] Existing modifiers are mostly linear in structure with low density of active groups, making it difficult to simultaneously achieve interface enhancement and silanol passivation. To address the problems of limited active sites, weak interfacial forces, and silanol interference with curing and bonding, there is an urgent need to develop novel and highly efficient modifiers. Summary of the Invention

[0004] The purpose of this invention is to provide a branched vinylphenyl polysiloxane and its preparation method, which solves the problems of few active sites and weak interfacial forces in existing modifiers, as well as the high content of silanol affecting the curing and bonding of addition systems.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a branched vinylphenyl polysiloxane, the reactive structural formula of which is shown below: , The T-link is a trifunctional linker, and the schematic diagram of the D-link structure is shown below. .

[0006] In some possible embodiments, the branched vinylphenyl polysiloxane contains 1.0 to 3.0% vinyl content and ≤0.1% silanol content.

[0007] In a second aspect, the present invention also provides a method for preparing a branched vinylphenyl polysiloxane as described in the first aspect, comprising the following steps: Vinyl difunctional silane monomer, phenyl difunctional silane monomer, alkyl difunctional silane monomer, first solid acid catalyst and first acetic acid are mixed in a certain proportion and subjected to reflux reaction; The temperature is lowered to below 30°C, and the first solid acid catalyst is filtered out to obtain the first filtrate. The first filtrate is then distilled at atmospheric pressure at the first temperature to obtain a polysiloxane precursor, namely a D-unit substance, wherein the molar ratio of vinyl difunctional unit: phenyl difunctional unit: alkyl difunctional unit is (0~3):(1~3):(3~10). A trifunctional chain segment silane monomer, a capping agent, a second acetic acid, and a second solid acid catalyst were added to the polysiloxane precursor to obtain a reaction solution. The reaction was carried out in a reaction vessel under atmospheric pressure to 0.02 MPa micro-positive pressure, with stirring, and the temperature was raised to 100~150℃ and maintained at pressure for 1~4 hours. The second solid acid catalyst is removed by filtration to obtain a second filtrate; the second filtrate is distilled at atmospheric pressure at a first temperature to obtain branched vinylphenyl polysiloxane, wherein the ratio of T-units to D-units is (1~3):(3~10).

[0008] In some possible embodiments, the first solid acid catalyst accounts for 1 to 10% of the total mass of the vinyl difunctional silane monomer, phenyl difunctional silane monomer, and alkyl difunctional silane monomer, and the amount of the first acetic acid added is 1 to 1.5 times the amount of silane material of the vinyl difunctional silane monomer, phenyl difunctional silane monomer, and alkyl difunctional silane monomer.

[0009] In some possible implementations, the reflux reaction specifically includes: reflux reaction at a temperature of 50~80°C for 3~8 hours.

[0010] In some possible implementations, the first temperature is 100~120°C.

[0011] In some possible embodiments, the vinyl difunctional chain silane monomer includes one or more of methyl vinyl dimethoxysilane, methyl vinyl diethoxysilane, 1,3-divinyl-1,3-dimethyldisiloxane, and 1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane. The phenyl difunctional chain silane monomer includes one or more of diphenylsilanediol, diphenylalkoxysilane, and 1,3-diphenyl-1,3-dimethyldisiloxane. The alkyl difunctional chain-linked silane monomer includes one or more of dimethyldialkoxysilane, methylpropyldialkoxysilane, methylvinyldialkoxysilane, methylphenyldialkoxysilane, methylethylsilane, and dimethylsilane. The trifunctional silane monomer includes trimethoxysilane or triethoxysilane, and the R group includes one or more of C1-C8 alkyl, phenyl, vinyl, amino and epoxy groups.

[0012] In some possible embodiments, the amount of the end-capping agent and the second acetic acid added is 0.5 to 1.2 times the amount of the D-chain unit added, and the mass of the second solid acid catalyst accounts for 1 to 10% of the mass of the reaction solution.

[0013] In some possible embodiments, the first and second solid acid catalysts include one or more of sulfonic acid-based cationic silicates, aluminosilicates, and sulfated zirconium oxide composite oxides.

[0014] In some possible implementations, the end-capping agent includes one or more of divinyltetramethyldisiloxane, hexamethyldisiloxane, and hydrogen-containing dual-capping agents.

[0015] It should be noted that the final product structure includes end-capping agent segments. Because the segments differ depending on the end-capping agent, the end-capping agent is not shown in the reaction structural diagram of branched vinylphenyl polysiloxane; its type is only described in the text description.

[0016] This invention provides a branched vinylphenyl polysiloxane and its preparation method, offering a novel modifier—branched vinylphenyl polysiloxane—with a vinyl content of 1.0~3.0% and a silanol content ≤0.1%. This solves the problems of existing modifiers having few active sites and weak interfacial forces, as well as the impact of high silanol content on the curing and adhesion of addition systems. The branched vinylphenyl polysiloxane of this invention, with its multi-terminal active sites and spatially branched structure, can effectively encapsulate fillers and participate in crosslinking reactions, enhancing interfacial forces; simultaneously, it can shield silanol groups, ensuring stable curing of the addition system, significantly improving filler dispersibility and system compatibility, thereby improving the mechanical properties and overall service performance of addition-cured silicone rubber. Attached Figure Description

[0017] Figure 1 The branched phenyl vinyl polysiloxane of Example 1 1 H NMR spectrum; Figure 2 The branched phenyl vinyl polysiloxane of Example 1 29 Si NMR spectrum. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. At the same time, in the description of the embodiments of this application, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0019] Example 1 This embodiment provides a branched vinylphenyl polysiloxane, the preparation method of which includes the following steps: 148g of vinylmethyldimethoxysilane, 484g of diphenyldimethoxysilane, 1368g of dimethyldimethoxysilane, 100g of sulfonic acid-based cationic silicone resin and 2400g of acetic acid were mixed evenly to lay the foundation for the formation of branched structure. The mixture was then subjected to a reflux reaction at 65°C for 5 hours.

[0020] The temperature was lowered to below 30°C, and the sulfonic acid-based cationic silicone resin was filtered out to obtain the first filtrate. The first filtrate was then distilled at atmospheric pressure at a first temperature of 110°C to obtain the polysiloxane precursor.

[0021] 100g of trimethoxysilane, 1360g of divinyltetramethyldisiloxane, 1360g of acetic acid and 231g of aluminosilicate were added to 1700g of polysiloxane precursor to obtain a reaction solution. The reaction was carried out in a reaction vessel at 0.01MPa with stirring, and the temperature was raised to 125℃ and maintained at pressure for 2.5h.

[0022] The aluminosilicate was removed by filtration to obtain a second filtrate; the second filtrate was then distilled at atmospheric pressure at a first temperature of 110°C to obtain branched vinylphenyl polysiloxane.

[0023] ¹H NMR and ²H NMR of branched vinylphenyl polysiloxane 9 Si NMR test results are as follows Figure 1 , 2 As shown; In other embodiments, hexamethyldisiloxane may also be used as a capping agent; the vinyl difunctional chain silane monomer may also be one or more of vinylmethyldiethoxysilane, 1,3-divinyl-1,3-dimethyldisiloxane, and 1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane; the phenyl difunctional chain silane monomer may also be one or more of diphenylsilanediol and 1,3-diphenyl-1,3-dimethyldisiloxane; the alkyl difunctional chain silane monomer may also be one or more of methylpropyldialkoxysilane, methylvinyldialkoxysilane, methylphenyldialkoxysilane, methylethylsilane, and dimethylsilane.

[0024] Example 2 This embodiment provides a branched vinylphenyl polysiloxane, the preparation method of which includes the following steps: 242g of diphenyldimethoxysilane, 762g of dimethyldimethoxysilane, 10.04g of zirconium oxide sulfate composite oxide, and 1004g of acetic acid were mixed evenly and refluxed at 50°C for 8 hours. Although no vinyl monomers were added to the linear chain in this embodiment, vinyl groups were introduced through a capping agent to ensure that the product was a branched vinylphenyl polysiloxane.

[0025] The temperature was lowered to below 30°C, and the sulfurized zirconium oxide composite oxide was filtered out to obtain the first filtrate. The first filtrate was then distilled at atmospheric pressure at a first temperature of 100°C to obtain the polysiloxane precursor.

[0026] Add 82g of triethoxysilane, 450g of vinyl end-capping agent (divinyltetramethyldisiloxane), 450g of acetic acid and 18.82g of sulfonic acid cationic silicone resin to 900g of polysiloxane precursor to obtain a reaction solution. React the solution in a reaction vessel under normal pressure, stirring, and heat to 100℃, maintaining the pressure for 4 hours.

[0027] The sulfonic acid-based cationic silicone resin was removed by filtration to obtain a second filtrate; the second filtrate was then distilled at atmospheric pressure at a first temperature of 110°C to obtain branched vinylphenyl polysiloxane.

[0028] Example 3 This embodiment provides a branched vinylphenyl polysiloxane, the preparation method of which includes the following steps: 444g of vinylmethyldimethoxysilane, 726g of diphenyldimethoxysilane, 1330g of dimethyldimethoxysilane, 250g of mixed catalyst (aluminosilicate and zirconium sulfate composite oxide mixed at a ratio of 1:1) and 3750g of acetic acid were mixed evenly to provide conditions for the formation of highly vinyl branched structures. The mixture was then refluxed at 80°C for 3 hours.

[0029] The mixture was cooled to below 30°C and filtered out to obtain the first filtrate. The first filtrate was then distilled at atmospheric pressure at a first temperature of 120°C to obtain the polysiloxane precursor.

[0030] 108g of trimethoxysilane, 2640g of hydrogen-containing double-ended head, 50g of vinyltrimethoxysilane (R group is vinyl), 2640g of acetic acid and 758.8g of aluminosilicate were added to 2200g of polysiloxane precursor to obtain a reaction solution. The reaction was carried out in a reaction vessel at 0.02MPa with stirring, and the temperature was raised to 150℃ and maintained at pressure for 1h.

[0031] The aluminosilicate was removed by filtration to obtain a second filtrate; the second filtrate was then distilled at atmospheric pressure at a first temperature of 120°C to obtain branched vinylphenyl polysiloxane.

[0032] Comparative Example 1 The only difference between this comparative example and Example 1 is that trimethoxysilane was not added.

[0033] Comparative Example 2 The only difference between this comparative example and Example 2 is that triethoxysilane was not added.

[0034] Comparative Example 3 The only difference between this comparative example and Example 3 is that trimethoxysilane was not added.

[0035] The following tests were performed on Examples 1-3 and Comparative Example 1, and the test results are shown in Table 1: 1. Polysiloxane molecular weight: determined by gel permeation chromatography (GPC) according to GB / T 21864-2008; the mobile phase was tested by tetrahydrofuran (THF), with a flow rate of 1.0 mL / min; 2. Viscosity: Tested using a rotational viscometer method, according to GB / T 10247-2008, at a test temperature of 25.0±0.1℃, using a #3 or #4 rotor; 3. Density: Tested using the specific gravity bottle method, according to GB / T 4472-2011; 4. Vinyl content: Tested by iodine addition titration according to GB / T 12008.6-2010; using glacial acetic acid-carbon tetrachloride (1:1) as solvent, iodine bromide solution as addition reagent, and sodium thiosulfate standard solution (0.1 mol / L) for back titration; 5. Si-OH content: The content was determined by acetylation titration according to ISO 14900:2017, using pyridine as solvent and acetic anhydride as acetylation reagent, refluxed in a water bath at 60℃ for 30 min, and titrated with sodium hydroxide standard solution (0.1 mol / L).

[0036] Table 1 The vinyl content of Examples 1-3 is in the range of 1.0~3.0%, and the silanol content is ≤0.1%, which solves the problems of few active sites and weak interfacial forces in existing modifiers, as well as the problem that high silanol content affects the curing and bonding of addition systems.

[0037] Comparing the molecular weights and viscosity at 25°C in Table 1, it can be seen that Example 1 is significantly better than Comparative Example 1, Example 2 is significantly better than Comparative Example 2, and Example 3 is significantly better than Comparative Example 3.

[0038] The branched structure of the branched vinylphenyl polysiloxane in this embodiment gives it good flowability and compatibility, allowing it to be well blended with other vinyl-containing organosilicon materials. The hardness and mechanical strength of the material can be improved through the crosslinking reaction of vinyl groups. The introduction of phenyl groups gives it certain temperature resistance and weather resistance, which matches the core performance characteristics of branched vinylphenyl polysiloxane. It can be used in sealing, coating and other applications in medium and low temperature environments, and its performance is not easily degraded by temperature changes.

[0039] Obviously, those skilled in the art can make various modifications and variations to the embodiments of the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A branched vinylphenyl polysiloxane, characterized in that, The reactive structural formula of the branched vinylphenyl polysiloxane is shown below: ， The T-link is a trifunctional linker, and the schematic diagram of the D-link structure is shown below. .

2. The branched vinylphenyl polysiloxane according to claim 1, characterized in that, The branched vinylphenyl polysiloxane contains 1.0-3.0% vinyl content and ≤0.1% silanol content.

3. The method for preparing a branched vinylphenyl polysiloxane according to claims 1-2, characterized in that, Includes the following steps: Vinyl difunctional silane monomer, phenyl difunctional silane monomer, alkyl difunctional silane monomer, first solid acid catalyst and first acetic acid are mixed in a certain proportion and subjected to reflux reaction; The temperature is lowered to below 30°C, and the first solid acid catalyst is filtered out to obtain the first filtrate. The first filtrate is then distilled at atmospheric pressure at the first temperature to obtain a polysiloxane precursor, namely a D-unit substance, wherein the molar ratio of vinyl difunctional unit: phenyl difunctional unit: alkyl difunctional unit is (0~3):(1~3):(3~10). A trifunctional chain segment silane monomer, a capping agent, a second acetic acid, and a second solid acid catalyst were added to the polysiloxane precursor to obtain a reaction solution. The reaction was carried out in a reaction vessel under atmospheric pressure to 0.02 MPa micro-positive pressure, with stirring, and the temperature was raised to 100~150℃ and maintained at pressure for 1~4 hours. The second solid acid catalyst is removed by filtration to obtain a second filtrate; the second filtrate is distilled at atmospheric pressure at a first temperature to obtain branched vinylphenyl polysiloxane, wherein the ratio of T-units to D-units is (1~3):(3~10).

4. The preparation method according to claim 3, characterized in that, The first solid acid catalyst accounts for 1 to 10% of the total mass of the vinyl difunctional silane monomer, phenyl difunctional silane monomer, and alkyl difunctional silane monomer, and the amount of the first acetic acid added is 1 to 1.5 times the amount of silane material of the vinyl difunctional silane monomer, phenyl difunctional silane monomer, and alkyl difunctional silane monomer.

5. The preparation method according to claim 3, characterized in that, The reflux reaction specifically includes: reflux reaction at a temperature of 50~80℃ for 3~8 hours.

6. The preparation method according to claim 3, characterized in that, The first temperature is 100~120℃.

7. The preparation method according to claim 3, characterized in that, The vinyl difunctional chain silane monomer includes one or more of methyl vinyl dimethoxysilane, methyl vinyl diethoxysilane, 1,3-divinyl-1,3-dimethyldisiloxane, and 1,3-divinyl-1,3-dimethyl-1,3-diphenyldisiloxane. The phenyl difunctional chain silane monomer includes one or more of diphenylsilanediol, diphenylalkoxysilane, and 1,3-diphenyl-1,3-dimethyldisiloxane. The alkyl difunctional chain-linked silane monomer includes one or more of dimethyldialkoxysilane, methylpropyldialkoxysilane, methylvinyldialkoxysilane, methylphenyldialkoxysilane, methylethylsilane, and dimethylsilane. The trifunctional silane monomer includes trimethoxysilane or triethoxysilane, and the R group includes one or more of C1-C8 alkyl, phenyl, vinyl, amino and epoxy groups.

8. The preparation method according to claim 3, characterized in that, The amount of the end-capping agent and the second acetic acid added is 0.5 to 1.2 times the amount of the D-chain segment material added, and the mass of the second solid acid catalyst accounts for 1 to 10% of the mass of the reaction solution.

9. The preparation method according to claim 3, characterized in that, The first and second solid acid catalysts include one or more of sulfonic acid-based cationic silicone resins, aluminosilicates, and sulfated zirconium oxide composite oxides.

10. The preparation method according to claim 3, characterized in that, The end-capping agent includes one or more of divinyltetramethyldisiloxane, hexamethyldisiloxane, and hydrogen-containing dual-capping agents.

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