Preparation method of pentamethyldisiloxane and preparation method of active silicone oil

Abstract

The invention provides a preparation method of pentamethyldisiloxane and a preparation method of active silicone oil. The preparation method of the pentamethyldisiloxane comprises the following steps: 1) mixing dimethyl monochlorosilane with long-chain alkyl chlorosilane to obtain a mixed solution, dropwise adding the mixed solution into water, reacting at 35-40 DEG C for 1-2 hours after dropwise adding, standing and separating liquid after reaction, taking an upper layer, and removing water and low boiling points; (2) adding hexamethyldisiloxane into the product obtained in the step (1), rearranging under the action of a first catalyst at 20-40 DEG C, filtering, distilling and collecting a fraction of a 60 cm Webster fractionating column at 85-87 DEG C; the first catalyst is concentrated sulfuric acid, solid acid or cation exchange resin. The preparation method of the 1, 1, 3, 3, 3-pentamethyldisiloxane, provided by the invention, is simple, low in cost, economical, environment-friendly and high in yield, and the purity of the obtained pentamethyldisiloxane is high.

Description

Technical Field

[0001] The invention relates to the technical field of silicone oil synthesis, and more specifically to a method for preparing pentamethyldisiloxane and a method for preparing active silicone oil. Background Art

[0002] 1,1,3,3,3-pentamethyldisiloxane (pentamethyldisiloxane for short) is an important organosilicon intermediate. This intermediate can undergo hydrosilylation reaction with other compounds containing unsaturated bonds to prepare substances with different reactive groups. It can be directly used as a capping agent to prepare various organosilicon polymers with inert functional groups at one end and reactive groups at the other end. Compared with dual-end active polymers and side-group active polymers, such organosilicon polymers can give materials new properties, such as low surface tension, high softness, high water and solvent resistance and good chemical stability. It is an excellent synthetic raw material and modifier for materials such as rubber and resin.

[0003] However, as a capping agent, if hexamethyldisiloxane or 1,3-tetramethyldisiloxane is mixed in 1,1,3,3,3-pentamethyldisiloxane, the performance of the synthesized silicone polymer will be greatly affected. In the prior art, one type of preparation method for 1,1,3,3,3-pentamethyldisiloxane is mainly to obtain the product by co-hydrolysis and condensation of equimolar amounts of dimethylethoxysilane and trimethylmonochlorosilane or dimethylmonochlorosilane and hexamethyldisilazane or trimethylsilanol and dimethylmonochlorosilane at low temperature. This type of preparation method will produce a large amount of by-products 1,1,3,3-tetramethyldisiloxane and hexamethyldisiloxane, and the overall yield of pentamethyldisiloxane is less than 30%. At the same time, the boiling points of 1,1,3,3-tetramethyldisiloxane and hexamethyldisiloxane are very close to that of 1,1,3,3,3-pentamethyldisiloxane, and it is extremely difficult to separate and obtain a relatively pure product pentamethyldisiloxane. This type of preparation method has high requirements for separation equipment. Another method for preparing pentamethyldisiloxane is to react an alkali metal silicon alkoxide with a dimethylhalosilane compound in an organic solvent in an acidic system at a molar ratio of 1:1. Although this method can achieve separation of byproducts and target products by optimizing the solvent, the alkali metal silicon alkoxide is expensive and has active performance and is easily ineffective, which is not conducive to large-scale production in factories. At the same time, in the prior art, such as CN101875662B, high hydrogen silicone oil and Grignard reagent are used to react and crack in solvents such as toluene and ether and then hydrolyze to prepare pentamethyldisiloxane, with a yield of about 50%. Although this method does not introduce chlorosilane, the high hydrogen silicone oil is more expensive and is mostly obtained by hydrolysis and condensation of chlorosilane. At the same time, the conditions for using Grignard reagents are more stringent, and the separation and purification of a large amount of byproduct magnesium salts from solvents and water is more difficult, which is not conducive to large-scale production. Summary of the invention

[0004] In order to solve or at least partially solve the problems in the prior art, the present invention provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane (also called pentamethyldisiloxane), which effectively improves the yield and purity of the product pentamethyldisiloxane.

[0005] The present invention provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, comprising the following steps:

[0006] 1) Dimethyl monochlorosilane and long-chain alkyl chlorosilane are mixed to obtain a mixed solution, and the mixed solution is dropped into water. After the dropwise addition is completed, the mixture is reacted at 35-40° C. for 1-2 hours. After the reaction is completed, the mixture is allowed to stand and separate, and the upper layer is taken to remove water and low boiling points;

[0007] 2) adding hexamethyldisiloxane to the product obtained in step 1), rearranging at 20-40° C. under the action of a first catalyst, filtering, and collecting fractions of a 60 cm Wei's fractionation column at 85-87° C. by distillation; wherein the first catalyst is concentrated sulfuric acid, a solid acid or a cation exchange resin.

[0008] In a preferred embodiment of the present invention, in order to further improve the yield and purity of the product, in step 1), the long-chain alkyl chlorosilane is dimethylpropyl chlorosilane, chloropropyldimethylchlorosilane, dimethylhexylchlorosilane, dimethyloctylchlorosilane, dimethyldecylchlorosilane or dimethyldodecylchlorosilane, preferably dimethyloctylchlorosilane.

[0009] In a preferred embodiment of the present invention, in order to further improve the yield and purity of the product, in step 1), the molar ratio of dimethyl monochlorosilane to long-chain alkyl chlorosilane is (1.1-1.3):(1.6-2.6). In step 1), the amount of water can be 75% to 100% of the total mass of dimethyl monochlorosilane and long-chain alkyl chlorosilane.

[0010] In a preferred embodiment of the present invention, in order to further improve the yield and purity of the product, in step 1), the dripping speed of the mixed solution into water is controlled to control the temperature of the reaction system between 20 and 25°C.

[0011] In a specific embodiment of the present invention, a dehydrating agent such as anhydrous magnesium sulfate may be used to remove water in step 1. The step of "removing low boiling points" may specifically be: removing low boiling point substances at -0.03 to -0.02 MPa and 50 to 60°C.

[0012] In a preferred embodiment of the present invention, in order to further improve the yield and purity of the product, in step 2), the first catalyst is a solid acid, more preferably solid acid HND-580. In this step, the amount of the first catalyst is 8-12% by mass of hexamethyldisiloxane.

[0013] In a preferred embodiment of the present invention, in order to further improve the yield and purity of the product, in step 2), the molar ratio of hexamethyldisiloxane to dimethylmonochlorosilane is 1:(1.1-1.3).

[0014] In one embodiment of the present invention, the specific steps of step 2) may include: adding hexamethyldisiloxane and the first catalyst to the product obtained in step 1), stirring the reaction at room temperature (e.g., 20-30°C) for 0.5-1h, heating to 35-40°C for rearrangement reaction for 1-2h, filtering and distilling to collect the fraction of 85-87°C, 60cm Wei's fractionation column. In the present invention, the collected fraction is 1,1,3,3,3-pentamethyldisiloxane.

[0015] In one embodiment of the present invention, if liquid catalysts such as concentrated sulfuric acid are used in step 2) and the subsequent synthesis of active silicone oil, after the reaction is completed, the pH is adjusted to 6-7 by neutralization with sodium acetate, sodium carbonate, etc., and then subsequent filtration and distillation steps are performed.

[0016] The preparation method provided by the present invention is used to prepare 1,1,3,3,3-pentamethyldisiloxane, and the yield can be as high as 80%, preferably as high as 85%, and further preferably as high as 89.5%. The purity of the obtained 1,1,3,3,3-pentamethyldisiloxane can be as high as 97%, and preferably as high as 98%.

[0017] The 1,1,3,3,3-pentamethyldisiloxane prepared by the preparation method has high purity. The 1,1,3,3,3-pentamethyldisiloxane obtained by the preparation method is used to prepare active silicone oil. The method is simple. The epoxy silicone oil synthesized by the preparation method is used in an organic potting compound. Under the condition that performance indicators such as strength remain unchanged, the "sudden increase" of viscosity during use can be improved, thereby improving the convenience of construction operation.

[0018] Another object of the present invention is to provide a method for preparing active silicone oil, the preparation method comprising the following steps:

[0019] S1, mixing the 1,1,3,3,3-pentamethyldisiloxane obtained in step 2) of the above preparation method with cyclosiloxane, and performing ring-opening rearrangement and impurity removal under the action of a second catalyst; the second catalyst is concentrated sulfuric acid, trifluoromethylsulfonic acid, perfluorosulfonic acid type ion exchange resin or solid acid;

[0020] S2, under nitrogen protection, mixing the product obtained in step S1 with a compound containing an unsaturated double bond and a third catalyst, reacting at 60-80° C., and removing impurities to obtain the product; the compound containing an unsaturated double bond is allyl glycidyl ether and / or 4-vinyl cyclohexene oxide; and the third catalyst is a keto-amine platinum catalyst.

[0021] That is, the preparation method of the active silicone oil comprises the following steps:

[0022] 1) Dimethyl monochlorosilane and long-chain alkyl chlorosilane are mixed to obtain a mixed solution, and the mixed solution is dropped into water. After the dropwise addition is completed, the mixture is reacted at 35-40° C. for 1-2 hours. After the reaction is completed, the mixture is allowed to stand and separate, and the upper layer is taken to remove water and low boiling points;

[0023] 2) adding hexamethyldisiloxane to the product obtained in step 1), rearranging at 20-40° C. under the action of a first catalyst, filtering, and collecting fractions at 85-87° C. and 60 cm by distillation on a Weiss fractionation column; the first catalyst is concentrated sulfuric acid, a solid acid, or a cation exchange resin;

[0024] S1, mixing the 1,1,3,3,3-pentamethyldisiloxane obtained in step 2) of the above preparation method with cyclosiloxane, and performing ring-opening rearrangement and impurity removal under the action of a second catalyst; the second catalyst is concentrated sulfuric acid, trifluoromethylsulfonic acid, perfluorosulfonic acid type ion exchange resin or solid acid;

[0025] S2, under nitrogen protection, mixing the product obtained in step S1 with a compound containing an unsaturated double bond and a third catalyst, reacting at 60-80° C., and removing impurities to obtain the product; the compound containing an unsaturated double bond is allyl glycidyl ether and / or 4-vinyl cyclohexene oxide; and the third catalyst is a keto-amine platinum catalyst.

[0026] The preferred embodiments of step 1) and step 2) are as described above and will not be described in detail here.

[0027] In a preferred embodiment of the present invention, in step S1, the cyclosiloxane is dimethylcyclosiloxane, methylphenylcyclosiloxane, methylvinylcyclosiloxane, octamethylcyclotetrasiloxane, tri(trifluoropropyl)cyclotrisiloxane, tetramethyltetravinylcyclotetrasiloxane, trimethyltriphenylcyclotrisiloxane or tetramethyltetraoctylcyclotetrasiloxane, preferably dimethylcyclosiloxane. In the ring-opening reaction in this area, dimethylcyclosiloxane is generally a dimethylcyclosiloxane mixed ring body, and D4 accounts for more than 95% in the commercially available dimethylcyclosiloxane mixed ring body, D5 is 4-5%, and the rest is D3. In the art, it is well known to those skilled in the art that the molecular weight of the commercially available dimethylcyclosiloxane mixed ring body is based on the molecular weight of octamethylcyclotetrasiloxane.

[0028] In one embodiment of the present invention, a liquid catalyst such as concentrated sulfuric acid is used in step S1, and after the reaction is completed, sodium acetate, sodium carbonate, etc. are used for neutralization to adjust the pH to 6-7 before proceeding to subsequent steps.

[0029] In a preferred embodiment of the present invention, in step S1, the second catalyst is preferably a solid acid, and further selected as solid acid YLCT-2. In a specific embodiment of the present invention, the solid acid YLCT-2 purchased from Elest New Material Technology Co., Ltd. is used as an example to describe the present invention in detail. Among them, the amount of the second catalyst is preferably 0.2 to 1.0% of the total mass of cyclosiloxane and 1,1,3,3,3-pentamethyldisiloxane in step 3).

[0030] In a preferred embodiment of the present invention, in step S1, the molar ratio of the cyclosiloxane to the hexamethyldisiloxane in step 2) is (3-10):1, preferably (5-8):1.

[0031] In a specific embodiment of the present invention, the specific steps of step S1 may include: under stirring conditions, dehydrating the cyclosiloxane at 70 to 80°C and -0.03 to -0.02 MPa for 0.5 to 1 h, adding the pentamethyldisiloxane obtained in step 2) and the second catalyst for ring-opening rearrangement reaction at 70°C to 90°C for 1 to 4 h, cooling and filtering, and distilling to remove low-boiling substances (the distillation conditions can be -0.05 to -0.04 MPa, 130 to 140°C) to obtain.

[0032] In a preferred embodiment of the present invention, in step S2, the molar ratio of the compound containing unsaturated double bonds to hexamethyldisiloxane (the raw material of step 2)) is (0.9-1):1.

[0033] In a preferred embodiment of the present invention, the third catalyst is preferably triphenylphosphine platinum. Wherein, triphenylphosphine platinum is preferably a platinum compound coordinated by a high hindered amine obtained by reacting chloroplatinic acid with 2,6-diisopropylaniline and acetylacetone (the molar ratio can be 1:(1-2):(1-2)). The preparation method of triphenylphosphine platinum used in the present invention preferably comprises the following steps: mixing 2,6-diisopropylaniline with acetylacetone and isopropanol, micro-refluxing for 10-15 hours, cooling to room temperature, deep cold filtration, taking the solid and mixing it with a tetrahydrofuran solution of chloroplatinic acid at 60-65°C for 1.5-2 hours, recrystallizing with dichloromethane, and drying. Wherein, the molar ratio of chloroplatinic acid to 2,6-diisopropylaniline and acetylacetone is 1:(1-2):(1-2).

[0034] In a preferred embodiment of the present invention, the additive of the third catalyst is preferably such that the Pt content in the system of step S2 is 20 to 100 ppm.

[0035] In a preferred embodiment of the present invention, the specific steps of step S2 may include: under nitrogen protection, activating the compound containing an unsaturated double bond with a third catalyst at 50-60°C for 0.5-1h, adding the product of step S1 dropwise, reacting at 60-80°C for 2-3h after the addition, slowly heating to 130-150°C, and blowing in dry nitrogen to remove low-boiling substances (the distillation conditions can be -0.03Mpa~-0.02MPa, 100-110°C), to obtain.

[0036] The preparation method of the single-ended active silicone oil provided by the present invention is simple, suitable for large-scale production, high in yield and low in cost. The obtained active silicone oil is used in the silicone potting glue, while the performance indicators such as strength remain unchanged, which greatly reduces the "sticky" performance and improves the convenience of construction operation.

[0037] Another object of the present invention is to provide the active silicone oil obtained by the above preparation method.

[0038] The beneficial effects of the present invention are:

[0039] 1) A method for preparing 1,1,3,3,3-pentamethyldisiloxane is proposed. The method is simple, low-cost, economical and environmentally friendly, with a high yield (up to 90%), and the obtained pentamethyldisiloxane has a high purity (up to 98%). Based on this method, epoxy silicone oil with any molecular weight and epoxy content can be prepared.

[0040] 2) A method for preparing an active silicone oil is proposed. Based on high-yield and high-purity pentamethyldisiloxane, the method for preparing the active silicone oil provided by the present invention is economical, environmentally friendly, and has low cost. The hydrogen content of the obtained active silicone oil is 0.025-0.06%, and the viscosity is 20-60 mPa.s. That is, the preparation method provided by the present invention can efficiently (high hydrosilation efficiency, epoxy value close to the theoretical value) obtain active silicone oil with an epoxy value of (0.025-0.055) mol / 100g and a viscosity of 20-60 mPa.s, which greatly improves the convenience of preparing such active silicone oil in actual production. DETAILED DESCRIPTION

[0041] The following examples are used to further describe the specific embodiments of the present invention. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. In the present invention, if there is no special explanation, "%" is a mass percentage. In the specific embodiments of the present invention, solid acid HND-580 is purchased from Jiangyin Nanda Synthetic Chemical Co., Ltd., and solid acid YLTC-2 is purchased from Yilaisite New Material Technology Co., Ltd.

[0042] Example 1

[0043] This embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, comprising the following steps:

[0044] (1) A mixture of 74.5 g of dimethyloctylchlorosilane and 22.7 g of dimethylmonochlorosilane was added dropwise to 78 g of water at room temperature. The temperature of the system was controlled between 20 and 25° C. After the addition was complete, the temperature was raised to 38° C. and kept for reaction for 1 hour. The mixture was allowed to stand for separation. The upper layer was taken, 10.2 g of anhydrous magnesium sulfate was added, dried, filtered, and distilled at -0.03 to -0.02 MPa at 58° C. until no bubbles were generated to obtain the product.

[0045] (2) To the product of step (1), 32.5 g of hexamethyldisiloxane and 3.3 g of catalyst solid acid HND-580 were added, and the mixture was stirred at room temperature (22-25° C.) for 0.5 h, and the mixture was heated to 36° C. for 1.5 h. The mixture was filtered, and distilled on a 60 cm Weiss fractionating column at 85-87° C. to obtain 26.8 g of 1,1,3,3,3-pentamethyldisiloxane having a gas chromatographic content of 98.2% (i.e., purity), with a yield of 90.3% (the yield in the present embodiment is calculated based on the amount of hexamethyldisiloxane that is not excessive, and hexamethyldisiloxane provides the trimethylsiloxy group in the pentamethyldisiloxane molecular chain).

[0046] The H-NMR spectrum data of 1,1,3,3,3-pentamethyldisiloxane obtained in this example are: 1 H-NMR (400MHz, CDCl 3 ,δ):0.02ppm(9H,Si CH 3 ),0.08ppm(6H,SiCH 3 ),4.52(1H,SiH).

[0047] Example 2

[0048] The present embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane. The preparation method is the same as that of Example 1, except that: in step (1), the long-chain alkyl chlorosilane is 0.36 mol of dimethylpropyl chlorosilane and 68 g of water; in step (2), the first catalyst is 3.3 g of concentrated sulfuric acid, and step (2) also includes adjusting the pH of the system to 6.12 with sodium acetate after the reaction is completed, filtering, and then distilling at 85-87° C. and a 60 cm Weier fractionation column.

[0049] The yield of 1,1,3,3,3-pentamethyldisiloxane obtained in this example is 89.1%, and the purity (ie, gas chromatography content) is 98.3%.

[0050] Example 3

[0051] The present embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, which is the same as that of Example 1, except that: in step (1), the long-chain alkyl chlorosilane is 0.36 mol of dimethyldecylchlorosilane and 86 g of water; and in step (2), the first catalyst is 3.3 g of NKC-9 cationic resin.

[0052] The yield of 1,1,3,3,3-pentamethyldisiloxane obtained in this example is 87.6% and the purity is 97.8%.

[0053] Example 4

[0054] This embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, comprising the following steps:

[0055] (1) A mixture of 103.4 g of dimethyloctylchlorosilane and 24.6 g of dimethylmonochlorosilane was added dropwise to 128 g of water at room temperature, and the temperature of the system was controlled between 20 and 25° C. After the addition was complete, the temperature was raised to 40° C. and kept for 2 h. The liquid was allowed to stand for separation, and the upper layer was taken. Anhydrous magnesium sulfate was added for drying, and the upper layer was filtered at -0.03 to -0.02 MPa and distilled at 58° C. until no bubbles were generated to obtain the product.

[0056] (2) Add 32.5 g of hexamethyldisiloxane and 3.9 g of catalyst solid acid HND-580 to the product of step (1), stir and react at room temperature (22-25° C.) for 0.5 h, heat to 40° C. and react for 2 h, filter, and distill on a 60 cm Wei'er fractionating column at 85-87° C. to obtain 26.6 g of 1,1,3,3,3-pentamethyldisiloxane with a gas chromatographic content of 98%, with a yield of 89.8%.

[0057] Example 5

[0058] This embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, comprising the following steps:

[0059] (1) A mixture of 62.1 g of dimethyloctylchlorosilane and 19.9 g of dimethylmonochlorosilane was added dropwise to 82 g of water at room temperature, and the temperature of the system was controlled between 20 and 25°C. After the addition was complete, the temperature was raised to 40°C and kept for reaction for 2 h. The liquid was allowed to stand for separation, and the upper layer was taken. Anhydrous magnesium sulfate was added for drying, and the upper layer was filtered at -0.03 to -0.02 MPa and distilled at 58°C until no bubbles were generated to obtain the product.

[0060] (2) To the product of step (1), 32.5 g of hexamethyldisiloxane and 2.3 g of catalyst solid acid HND-580 were added, and the mixture was stirred at room temperature (22-25° C.) for 0.5 h, and the mixture was heated to 40° C. for 2 h, and filtered. The mixture was distilled on a 60 cm Weiss fractionating column at 85-87° C. to obtain 26 g of 1,1,3,3,3-pentamethyldisiloxane with a gas chromatographic content of 97.9%, and the yield was 87.5%.

[0061] Example 6

[0062] This embodiment provides a method for preparing 1,1,3,3,3-pentamethyldisiloxane, comprising the following steps:

[0063] (1) A mixture of 115.8 g of dimethyloctylchlorosilane and 26.5 g of dimethylmonochlorosilane was added dropwise to 171 g of water at room temperature. The temperature of the system was controlled between 20 and 25° C. After the addition was complete, the temperature was raised to 40° C. and the mixture was kept for 2 h. The mixture was allowed to stand for separation. The upper layer was taken, dried with anhydrous magnesium sulfate, filtered, and distilled at -0.03 to -0.02 MPa at 58° C. until no bubbles were generated to obtain the product.

[0064] (2) Add 32.5 g of hexamethyldisiloxane and 4.9 g of concentrated sulfuric acid to the product of step (1), stir and react at room temperature (22-25° C.) for 0.5 h, heat to 40° C. for 2 h, wash with water until the pH value is 6.4, filter, and distill on a 60 cm Wei'er fractionating column at 85-87° C. to obtain 24.8 g of 1,1,3,3,3-pentamethyldisiloxane with a gas chromatographic content of 98.2%, with a yield of 83.6%.

[0065] Example 7

[0066] This embodiment provides a method for preparing active silicone oil, comprising the following steps:

[0067] (3) 296.6 g of DMC dimethylcyclosiloxane mixed ring body (1 mol of octamethylcyclotetrasiloxane) was mixed with 36.8 g of 1,1,3,3,3-pentamethyldisiloxane, the product of step (2) obtained in Example 1, and 1.4 g of catalyst perfluorosulfonic acid resin (purchased from Shanghai Hancheng Industrial Co., Ltd. (Hancheng Technology)), and reacted at 80° C. for 2.5 h, cooled, filtered, and distilled at -0.04 to -0.03 MPa, 140° C. until there were no bubbles, to obtain 326.4 g of product.

[0068] (4) 21g of allyl glycidyl ether and the third catalyst (the amount of the third catalyst is such that the Pt content in the system of step (4) is 30ppm) are activated and reacted at 55°C for 0.5h, the product of step (3) is added dropwise, and the mixture is kept at 72-75°C for 2h after the addition is complete, and distilled at -0.05Mpa to -0.04MPa and 80°C until there are no bubbles, cooled, 5g of dry activated carbon is added, heated to 70°C and stirred for 0.5h, cooled and filtered, and 346.1g of colorless transparent liquid, i.e., activated silicone oil, is obtained, and the epoxy value is 0.054mol / 100g. The epoxy value of the present invention is obtained by testing in accordance with GB / T 1677-2008, and the viscosity is tested using a Brookfield DV2T viscometer.

[0069] Wherein, the synthesis steps of the third catalyst are:

[0070] In a 50 ml three-necked flask, add 0.5 g of 2,6-diisopropylaniline, 0.28 g of acetylacetone and 10 ml of isopropanol, heat to 80 °C and reflux for 15 h, cool to room temperature, deep freeze at -20 °C and filter, take the solid, mix the obtained solid powder with 1.4 g of chloroplatinic acid hexahydrate in tetrahydrofuran solution, and react at 65 °C for 2 h. After the reaction, use dichloromethane to recrystallize and dry to obtain an orange-yellow powder catalyst.

[0071] Experimental example

[0072] The colorless transparent liquid active silicone oil obtained as the product of Example 7 of the present invention was used to prepare a potting adhesive for performance testing.

[0073] Raw materials for preparing potting glue: 50 MPa·s end-epoxy silicone oil (epoxy value 0.05), Wuhan Jiyesheng Chemical Co., Ltd.; spherical alumina, 50 μm, 10 μm, 2 μm, Qinghe Chaotai Metal Materials Co., Ltd.; nano zinc oxide, Qinghe Chaotai Metal Materials Co., Ltd.; polypropylene glycol diglycidyl ether, methyl hexahydrophthalic anhydride, tris-(dimethylaminomethyl)phenol, Macklin's reagent.

[0074] Preparation process:

[0075] Comparative Example 1

[0076] Preparation of component A

[0077] 100 parts by weight of epoxy end silicone oil with an epoxy value of 0.05, 400 parts by weight of 50 μm spherical alumina, 150 parts by weight of 10 μm spherical alumina, 70 parts by weight of 2 μm spherical alumina, and 20 parts by weight of 200 nm zinc oxide are stirred and mixed evenly in a high-speed disperser, and ground three times on a three-roll mill. Finally, component A is placed in a vacuum oven at room temperature and vacuumed to -0.0995 MPa for degassing for 30 minutes to obtain component A.

[0078] Preparation of component B

[0079] Add 30 parts by weight of polypropylene glycol diglycidyl ether, 30 parts by weight of methyl hexahydrophthalic anhydride, and 0.2 parts by weight of tris-(dimethylaminomethyl)phenol into a mixer according to the proportions in the table, mix and stir at room temperature for 30 minutes, and after mixing evenly, filter through a 300-mesh filter and seal and package to form component B.

[0080] Experimental Example 1

[0081] The difference from the control example is that in component A, 95 parts by weight of the epoxy-terminated silicone oil with an epoxy value of 0.05 and 5 parts of the product of Example 7 are used to replace 100 parts of the epoxy-terminated silicone oil with an epoxy value of 0.05 in the control example.

[0082] Experimental Example 2

[0083] The difference from the control example is that component A uses 90 parts by weight of 90 parts by weight of epoxy-terminated silicone oil with an epoxy value of 0.05 and 10 parts of the product of Example 7 to replace 100 parts of epoxy-terminated silicone oil with an epoxy value of 0.05 in the control example.

[0084] Experimental Example 3

[0085] The difference from the control example is that component A uses 85 parts by weight of epoxy-terminated silicone oil with an epoxy value of 0.05 and 15 parts of the product of Example 7 to replace 100 parts of epoxy-terminated silicone oil with an epoxy value of 0.05 in the control example.

[0086] The A and B components in the comparative example and the experimental example were mixed at a mass ratio of 100:10 at room temperature, and then cured in an oven at 125°C / 1h to test the performance. The viscosity was tested according to GB / T2794-2013, the density was tested according to GB / T533-208, the thermal conductivity was tested according to GB / T11205-2009, the Shore A hardness was tested according to GB / T531-1999, and the tensile strength and elongation were tested according to GB / T528-2009. The specific test data are shown in Table 1:

[0087] Table 1

[0088]

[0089] From the comparison between Experimental Examples 1 to 3 and Control Example 1, it is found that as the amount of the silicone oil product of the present invention increases, the viscosity of the potting compound decreases and the hardness decreases after curing, further proving that the single-active silicone oil with the desired performance is obtained in Example 7 of the present invention.

[0090] Finally, the method of the present invention is only a preferred embodiment and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing 1,1,3,3,3-pentamethyldisiloxane, characterized in that: The steps include: 1) Dimethyl monochlorosilane and long-chain alkyl chlorosilane are mixed to obtain a mixed solution, and the mixed solution is dropped into water. After the dropwise addition is completed, the mixture is reacted at 35-40° C. for 1-2 hours. After the reaction is completed, the mixture is allowed to stand and separate, and the upper layer is taken to remove water and low boiling points; 2) adding hexamethyldisiloxane to the product obtained in step 1), rearranging at 20-40° C. under the action of a first catalyst, filtering, and collecting fractions of a 60 cm Wei's fractionation column at 85-87° C. by distillation; wherein the first catalyst is concentrated sulfuric acid, a solid acid or a cation exchange resin.

2. The preparation method according to claim 1, characterized in that: In step 1), the long-chain alkyl chlorosilane is dimethylpropyl chlorosilane, chloropropyldimethylchlorosilane, dimethylhexylchlorosilane, dimethyloctylchlorosilane, dimethyldecylchlorosilane or dimethyldodecylchlorosilane, preferably dimethyloctylchlorosilane.

3. The preparation method according to claim 1, characterized in that: In step 1), the molar ratio of the dimethyl monochlorosilane to the long-chain alkyl chlorosilane is (1.1-1.3):(1.6-2.6), and the amount of water used is 75%-100% of the total mass of the dimethyl monochlorosilane and the long-chain alkyl chlorosilane.

4. The preparation method according to claim 1, characterized in that: In step 1), the temperature of the reaction system is controlled between 20 and 25° C. by dropping the mixed solution into water at a dropping speed.

5. The preparation method according to any one of claims 1 to 4, characterized in that: In step 2), the first catalyst is solid acid HND-580; the amount of the first catalyst used is 8-12% by mass of hexamethyldisiloxane.

6. The preparation method according to any one of claims 1 to 4, characterized in that: In step 2), the molar ratio of hexamethyldisiloxane to dimethylmonochlorosilane is 1:(1.1-1.3).

7. A method for preparing active silicone oil, characterized in that: The steps include: S1, mixing 1,1,3,3,3-pentamethyldisiloxane obtained by the preparation method according to any one of claims 1 to 6 with cyclosiloxane, and performing ring-opening rearrangement and impurity removal under the action of a second catalyst; the second catalyst is concentrated sulfuric acid, trifluoromethylsulfonic acid, perfluorosulfonic acid type ion exchange resin or solid acid; S2, under nitrogen protection, mixing the product obtained in step S1 with a compound containing an unsaturated double bond and a third catalyst, reacting at 60-80° C., and removing impurities to obtain the product; the compound containing an unsaturated double bond is allyl glycidyl ether and / or 4-vinyl cyclohexene oxide; and the third catalyst is a keto-amine platinum catalyst.

8. The preparation method according to claim 7, characterized in that: In step S1, the cyclosiloxane is dimethylcyclosiloxane, methylphenylcyclosiloxane, methylvinylcyclosiloxane, octamethylcyclotetrasiloxane, tri(trifluoropropyl)cyclotrisiloxane, tetramethyltetravinylcyclotetrasiloxane, trimethyltriphenylcyclotrisiloxane or tetramethyltetraoctylcyclotetrasiloxane, preferably dimethylcyclosiloxane; the molar ratio of the cyclosiloxane to hexamethyldisiloxane is (3-10):1, and the amount of the second catalyst is 0.2-1.0% of the total mass of the cyclosiloxane and the product obtained in step 2).

9. The preparation method according to claim 7, characterized in that: In step S2, in step 4), the molar ratio of the compound containing unsaturated double bonds to hexamethyldisiloxane is (0.9-1):1, and the amount of the third catalyst added is such that the Pt content in the system of step 4) is 20-100 ppm.

10. The active silicone oil obtained by the preparation method according to any one of claims 7 to 9.

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