An alkoxyl-terminated silicone polymer, a method for preparing the same, and an application thereof

Abstract

The application provides an alkoxy-terminated organosilicon polymer and a preparation method and application thereof. The preparation method comprises the following steps: S1, under the protection of nitrogen, mixing DMC, acetic anhydride and an acid catalyst, reacting at 110-113 DEG C, washing to neutral, taking an oil phase, and obtaining a first silicon oil after removing low-boiling-point substances; S2, under the protection of nitrogen, mixing the first silicon oil obtained in the step S1, a monofunctional trimethylsilane and an alkali catalyst, reacting at 40-50 DEG C for 2-4 hours, and then adding orthosilicate or alkyltrialkoxysilane to continue reacting for 2-4 hours. The preparation method provided by the application synthesizes the alkoxy-terminated organosilicon polymer with high reactivity, which can effectively improve the dispersibility of the powder (such as a filler) as a powder treating agent, and can effectively improve the heat conduction performance and tensile strength of the product (especially a condensation type heat-conducting adhesive).

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of synthesis of silicone oil in heat-conducting silicone rubber, and more particularly to an alkoxy-terminated organosilicon polymer, a preparation method and application thereof. BACKGROUND

[0002] The use of inorganic powder such as white carbon black, calcium carbonate, silicon carbide, magnesium oxide, etc. as filler to prepare composite materials can significantly improve the physical properties of the composite materials. However, the surface hydroxyl groups of such powders have poor compatibility with organic resin systems, resulting in a large interfacial tension between the raw materials and poor modification effect. Therefore, a silicon functional group is usually used to hydrophobically treat the powder. This method has been widely used at present.

[0003] However, in this method, the functional silane and its oligomers release small molecules during use, resulting in high VOC, and release a large amount of gaseous small molecules, which can easily lead to poor mechanical properties. However, if the small molecules are not released in time, the electrical properties of the composite material will be poor, resulting in poor thermal conductivity of the material modified by the silane compound with small molecules. In the prior art, most of the small molecule silanes given have poor modification effect on these inorganic powders, and cannot meet the requirement of high thermal conductivity. SUMMARY

[0004] The first object of the present application is to provide a preparation method of an alkoxy-terminated organosilicon polymer. The alkoxy-terminated organosilicon polymer obtained by the preparation method can be used as a powder treatment agent, which can effectively improve the dispersibility of the powder. The preparation method has mild conditions and is economical and environmentally friendly.

[0005] The preparation method of the alkoxy-terminated organosilicon polymer comprises the following steps:

[0006] S1, under nitrogen protection, mixing DMC, acetic anhydride and acid catalyst, reacting at 110-113℃, washing with water until neutral, taking the oil phase, and removing low-boiling substances to obtain a first silicone oil;

[0007] S2, under nitrogen protection, mixing the first silicone oil obtained in step S1, monofunctional trimethylsilane and base catalyst, reacting at 40-50℃ for 2-4h, and then adding orthosilicate or alkyltrialkoxysilane to continue reacting for 2-4h.

[0008] In the art, it is well known to those skilled in the art that DMC is a mixture of dimethylcyclosiloxanes (also referred to as dimethylcyclosiloxane mixture), wherein the main component (more than 90%) is octamethylcyclotetrasiloxane (also referred to as D4), and further contains a part of hexamethylcyclotrisiloxane (also referred to as D3), decamethylcyclopentasiloxane (also referred to as D5) and dodecamethylcyclohexasiloxane (also referred to as D6). In the art, the molecular weight of DMC is usually calculated based on D4. In the technical solution of the present application, DMC can be purchased on the market, for example, in the embodiments of the present application, DMC is purchased from Jiangxi Xinghuo Silicone Co., Ltd.

[0009] In a preferred embodiment of the present application, in order to further improve the modification performance of the polymer, in step S1, the molar ratio of DMC to acetic anhydride is (6-10):1.

[0010] In a preferred embodiment of the present application, in order to further improve the modification performance of the polymer, in step S1, the acid catalyst is 0.2wt%-1wt% of DMC. In the preferred embodiment of the present application, the acid catalyst is sulfuric acid, hydrochloric acid, oxalic acid or solid acid, and is further preferably sulfuric acid.

[0011] In a specific embodiment of the present application, the reaction time in step S1 is preferably 3-5h. In step S1, after the reaction is completed, a small amount of water can be used for washing multiple times until the system is neutral (pH=6-7), then the oil phase is taken out, and the obtained oil phase is distilled to remove low boiling point substances to obtain the first silicone oil. In this step, the specific steps for removing low boiling point substances include: distillation at 80-100℃, -0.04-0.05MPa until no obvious bubbles are generated. In the specific embodiment of the present application, the obtained first silicone oil is transparent.

[0012] In a preferred embodiment of the present application, in order to further improve the modification performance of the polymer, in step S2, the monofunctional trimethylsilane is methoxytrimethylsilane, ethoxytrimethylsilane, isopropenyloxytrimethylsilane, and is further preferably isopropenyloxytrimethylsilane.

[0013] In a preferred embodiment of the present application, in order to further improve the modification performance of the polymer, in step S2, the orthosilicate or alkyltrialkoxysilane is one or more of methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, and is further preferably methyltrimethoxysilane.

[0014] In a preferred embodiment of the present application, in order to further improve the modification performance of the polymer, in step S2, the molar ratio of the acetic anhydride, the monofunctional silane and the orthosilicate (alkyltrialkoxysilane) is 1: (0.9-1): (0.9-1).

[0015] In a preferred embodiment of the present application, in order to further improve the modification performance of the polymer, in step S2, the base catalyst is potassium hydroxide and / or lithium hydroxide, and is further preferably potassium hydroxide. In a preferred embodiment of the present application, in order to further improve the modification performance of the polymer, the base catalyst is 0.03wt%-0.1wt% of the DMC, and is preferably 0.05wt%-0.07wt%.

[0016] In a specific embodiment of the present application, in step S2, the orthosilicate or alkyltrialkoxysilane is added to the reaction system in a slow dropwise manner, and the dropwise adding speed is controlled to maintain the temperature of the reaction system at no more than 50°C. In a preferred embodiment of the present application, after the orthosilicate or alkyltrialkoxysilane is added, the reaction is continued at 40-50°C for 2-4h.

[0017] In a specific embodiment of the present application, in step S2, after the reaction is completed, the system is adjusted to be neutral, and after filtration (to remove inorganic salts) and removal of low-boiling substances, the product is obtained. In this step, the low-temperature distillation can specifically include: distillation at -0.06 to -0.04 MPa and 80-100°C until no obvious bubbles are generated. The system can be adjusted to be neutral (pH 6-7) using a neutralizing agent. The neutralizing agent can be acetic acid and / or sulfuric acid, and is preferably acetic acid.

[0018] The alkoxyl-terminated organosilicon polymer obtained by the preparation method provided by the present application can be used as a treating agent, and can effectively improve the dispersion performance of a powder (such as a filler), and improve the thermal conductivity and tensile strength of silicone rubber.

[0019] That is, another object of the present application is to provide an alkoxyl-terminated organosilicon polymer obtained by the above preparation method.

[0020] Still another object of the present application is to provide the use of the alkoxyl-terminated organosilicon polymer obtained by the above preparation method and the above preparation method in the preparation of a condensation type thermal conductive silicone rubber.

[0021] In the detailed description of the present application, the alkoxyl-terminated organosilicon polymer provided by the present application can be used as a treating agent to modify the filler, and the amount of addition can be 0.9-1 wt% of the filler. In the thermal conductive silicone rubber, the filler can include light calcium carbonate, heavy calcium carbonate, aluminum oxide, silicon carbide, etc. In the detailed description of the present application, heavy calcium carbonate, aluminum oxide, and silicon carbide with a mass ratio of 2:3:3 can be used to illustrate the present application. The alkoxyl-terminated organosilicon polymer provided by the present application can be used to treat the silicone rubber with filler commonly used in the art, thereby improving the thermal conductivity and tensile strength. In the detailed description of the present application, the silicone rubber with methyl vinyl silicone gum as the base material can be used to illustrate the present application.

[0022] The present application has the following advantages:

[0023] 1) The present application innovatively uses a specific reaction sequence to synthesize an alkoxyl-terminated organosilicon polymer with high reactivity by two-step condensation reaction of monofunctional silane and orthosilicate, which can effectively improve the dispersibility of powder (such as filler) as a powder treating agent, and can effectively improve the thermal conductivity and tensile strength of the product (especially the condensation type thermal conductive silicone rubber).

[0024] 2) The synthesis method of the alkoxyl-terminated organosilicon polymer provided by the present application has mild conditions, is economical and environmentally friendly. DETAILED DESCRIPTION

[0025] The detailed description of the present application will be further described in combination with the examples. The following examples are used to illustrate the present application, but not to limit the scope of the present application.

[0026] In the examples, the specific conditions are not specified, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained by market purchase. For example, the DMC used in the embodiments of the present application is purchased from Jiangxi Xinghuo Silicone Co., Ltd.

[0027] Example 1

[0028] The embodiments of the present application provide an alkoxyl-terminated organosilicon polymer, a preparation method and application thereof, which include the following steps:

[0029] 1) Synthesis of the first silicone oil

[0030] Under nitrogen protection, 192.8 g of DMC, 10.21 g of acetic anhydride, and 0.39 g of sulfuric acid were stirred at 110-113°C for 3 h, then cooled, washed with water until neutral, and then separated by standing for 2 h. The low boiling point was removed at 100°C and -0.04 MPa to -0.05 MPa until no low boiling point was produced and no obvious bubbles were generated. The transparent first silicone oil was obtained after cooling.

[0031] 2) Synthesis of the second silicone oil

[0032] The first silicone oil obtained in Step S1 was reacted with 0.13 g of KOH and 12.4 g of isopropenyltrimethylsilane at 45°C for 2.5 h under nitrogen protection, 14.6 g of methyl orthosilicate was slowly added while maintaining the temperature of the system at 45 ± 5°C, and after the addition was completed, the reaction was continued at 45°C for 3 h. Acetic acid was added to neutralize the mixture to pH 6.42, inorganic salts were removed by filtration, and the product was distilled under reduced pressure at -0.06 MPa to -0.04 MPa and 100°C until no obvious bubbles were generated, to obtain 203.24 g of an alkoxyl-terminated silicone polymer.

[0033] Example 2

[0034] The method provided in this example is the same as that in Example 1, except that

[0035] In Step S1, the molar ratio of DMC to acetic anhydride was 7.8:1, and the amount of sulfuric acid was 0.5 wt% of the mass of DMC.

[0036] In Step S2, the molar ratio of acetic anhydride, isopropenyltrimethylsilane to methyl orthosilicate was 1:0.9:0.9, and the amount of KOH was 0.05 wt% of the mass of DMC.

[0037] Example 3

[0038] The method provided in this example is the same as that in Example 1, except that

[0039] In Step S1, the molar ratio of DMC to acetic anhydride was 9:1, and the amount of sulfuric acid was 0.8 wt% of the mass of DMC.

[0040] In Step S2, the molar ratio of acetic anhydride, isopropenyltrimethylsilane to methyl orthosilicate was 1:1:1, and the amount of KOH was 0.07 wt% of the mass of DMC.

[0041] Example 4

[0042] The method provided in this example is the same as that in Example 1, except that in Step S2, the monofunctional silane was methoxymethylsilane, and the amount of KOH was 0.03 wt% of the mass of DMC.

[0043] Example 5

[0044] The method provided in this example is the same as that in Example 1, except that in Step S2, the monofunctional silane was ethoxymethylsilane, and the amount of KOH was 0.1 wt% of the mass of DMC.

[0045] Example 6

[0046] The method provided in the embodiment is the same as that in embodiment 1, except that,

[0047] In step S1, the molar ratio of DMC to acetic anhydride is 11:1, and the amount of sulfuric acid is 1.2 wt% of the mass of DMC.

[0048] In step S2, tetraethyl orthosilicate is used instead of methyltrimethoxysilane.

[0049] In step S2, the molar ratio of acetic anhydride, isopropenyltrimethylsilane and tetraethyl orthosilicate is 1:1.1:1.1, and the amount of KOH is 0.15 wt% of the mass of DMC.

[0050] Example 7

[0051] The method provided in the embodiment is the same as that in embodiment 1, except that, in step S1, the acid catalyst is hydrochloric acid, in step S2, the base catalyst is lithium hydroxide, and in step S2, methyltrimethoxysilane is used instead of methyltrimethoxysilane.

[0052] Example 8

[0053] The method provided in the embodiment is the same as that in embodiment 1, except that, in step S1, the acid catalyst is oxalic acid, and in step S2, propyltrimethoxysilane is used instead of methyltrimethoxysilane.

[0054] Example 9

[0055] The method provided in the embodiment is the same as that in embodiment 1, except that, in step S1, the acid catalyst is HND-582 solid acid, and in step S2, propyltrimethoxysilane is used instead of methyltrimethoxysilane.

[0056] Example 10

[0057] The method provided in the embodiment is the same as that in embodiment 1, except that,

[0058] In step S1, the molar ratio of DMC to acetic anhydride is 5.5:1, and the amount of sulfuric acid is 0.15 wt% of the mass of DMC.

[0059] In step S2, butyltrimethoxysilane is used instead of methyltrimethoxysilane.

[0060] In step S2, the molar ratio of acetic anhydride, isopropenyltrimethylsilane and butyltrimethoxysilane is 1:0.85:0.85, and the amount of KOH is 0.02 wt% of the mass of DMC.

[0061] Comparative Example 1

[0062] The method provided in the comparative example is the same as that in embodiment 1, except that,

[0063] 2) Synthesis of the second silicone oil

[0064] The first silicon oil obtained in Step S1 was reacted with 0.13 g of KOH and 14.6 g of methyl orthosilicate at 45°C for 2.5 h under nitrogen protection, 12.4 g of isopropenyltrimethylsilane was slowly added dropwise while maintaining the temperature of the system at 45±5°C, and after the dropwise addition was completed, the reaction was maintained at 45°C for 3 h. Acetic acid was added to neutralize the system to pH 6.42, and then the system was distilled under reduced pressure at -0.06 MPa to -0.04 MPa and 100°C until no obvious bubbles were generated to obtain the product.

[0065] Experimental Example

[0066] 20 parts of heavy calcium carbonate, 30 parts of alumina and 30 parts of silicon carbide were vacuum dried at 100°C for 4 h, and then were put into a high-speed mixer. 0.8 parts by mass of the treating agent obtained in the examples or comparative examples was added under mixing, and stirring was performed for 30 min to obtain a filler, which was used as needed. The treating agents provided in Comparative Examples 2 to 4 were hydroxyl dimethyl silicone oil, vinyl tris(methoxyethoxy)silane and tetraisopropyl bis(dioctyl phosphityloxy) titanate, respectively.

[0067] The mixing sample of the silicone rubber composite was prepared as follows: 20 parts of methyl vinyl silicone raw rubber with a vinyl content of 0.03% was added to a roller, and after the rubber was wrapped around the roller, 3 parts of precipitated white carbon black was added. After mixing for 5 times, 0.1 parts of benzoyl peroxide and 2 parts of carbon nanotubes were added, and the rubber was mixed again and then was sheeted. After cold pressing and molding, the rubber was twice vulcanized and then was cooled to obtain a sample.

[0068] The tensile strength and thermal conductivity of the sample were tested according to ASTM D412 and ASTM 1461-01, respectively, and the specific performance results are shown in Table 1.

[0069] Table 1 Performance Results

[0070] Treatment Tensile strength (KN / mm) Thermal conductivity (W / m.K) Example 1 1.8 4.5 Example 2 1.7 4.3 Example 3 1.6 4.2 Example 4 1.7 4.4 Example 5 1.5 4.3 Example 6 1.4 4.1 Example 7 1.6 4.2 Example 8 1.6 4.2 Example 9 1.3 4.0 Example 10 1.3 3.9 Comparative Example 1 1.2 3.8 Comparative Example 2 1.2 3.6 Comparative Example 3 1.0 3.1 Comparative Example 4 1.2 3.3

[0071] Finally, the method of the present application is only a preferred embodiment, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an alkoxy-terminated organosilicon polymer, comprising the following steps: S1. mixing DMC, acetic anhydride and an acid catalyst under nitrogen protection, and reacting at 110-113℃, then washing with water until neutral, taking the oil phase, and removing low-boiling substances to obtain a first silicone oil; S2. mixing the first silicone oil obtained in step S1, a monofunctional trimethylsilane and a base catalyst under nitrogen protection, and reacting at 40-50℃ for 2-4h, then adding orthosilicate or alkyltrialkoxysilane and continuing to react for 2-4h; In step S1, the molar ratio of the DMC to the acetic anhydride is (6-10) : 1, and the acid catalyst is 0.2wt%-1wt% of the DMC; In step S2, the molar ratio of the acetic anhydride, the monofunctional trimethylsilane and the orthosilicate is 1: (0.9-1) : (0.9-1) ; The monofunctional trimethylsilane is methoxytrimethylsilane, ethoxytrimethylsilane or isopropenyloxytrimethylsilane.

2. The production method according to claim 1, characterized by, In step S1, the acid catalyst is sulfuric acid, hydrochloric acid, oxalic acid or a solid acid.

3. The preparation method according to claim 2, characterized in that, The acid catalyst is sulfuric acid.

4. The production method according to any one of claims 1 to 3, characterized by, The monofunctional trimethylsilane is isopropenyloxytrimethylsilane.

5. The production method according to any one of claims 1 to 3, characterized by, In step S2, the base catalyst is potassium hydroxide and / or lithium hydroxide.

6. The production method according to claim 5, wherein The base catalyst is potassium hydroxide.

7. The method according to any one of claims 1-3, in step S2, the orthosilicate or alkyltrialkoxysilane is one or more of methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, butyltrimethoxysilane, tetra (2-methoxyethoxy) silane, methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane and propyltriethoxysilane.

8. The preparation method according to claim 7, characterized in that, The orthosilicate is methyltrimethoxysilane.

9. The production method according to any one of claims 1 to 3, characterized by, In step S2, the base catalyst is 0.03wt%-0.1wt% of the DMC.

10. The method of claim 9, wherein, The base catalyst is 0.05wt%-0.07wt% of the DMC.

11. An alkoxy-terminated organosilicon polymer obtained by the method of any one of claims 1-10.

12. Use of the alkoxy-terminated organosilicon polymer of claim 11 in preparing a condensation-type heat-conducting silicone rubber.