A low viscosity alkoxyl-rich hyperbranched silicone resin, its preparation method and use

Abstract

The application discloses a kind of low viscosity alkoxyl-rich hyperbranched silicone resin and its preparation method and application, belong to organic polymer material technical field.The low viscosity alkoxyl-rich hyperbranched silicone resin is prepared by using tri-functional group siloxane monomer containing alkyl or aromatic group as raw material, by hydrolysis nucleation, condensation growth, end-capping, purification treatment;Among them, the alkoxyl content is not less than 3%, and the viscosity is not higher than 1000 mPa·s.The tri-functional group siloxane monomer containing alkyl or aromatic group and the di-functional group siloxane monomer containing alkyl or aromatic group occur controllable hydrolysis polycondensation reaction by catalyst action, and the hyperbranched silicone resin with highly branched topological structure and rich in alkoxyl functional group is prepared, so that the resin viscosity is low while having high alkoxyl content, and the hyperbranched silicone resin can form high-temperature-resistant low-dielectric organic silicon transparent coating after self-curing, the coating preparation process is simple and controllable, and is suitable for scale production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of organic polymer materials, and more particularly relates to a low-viscosity alkoxyl-rich hyperbranched silicone resin as well as a preparation method and application thereof. BACKGROUND

[0002] High-heat-stable and low-dielectric-loss silicone resins are widely used in semiconductor packaging, flat panel display, electronic product protection and communication equipment, aiming at reducing electromagnetic interference and improving signal transmission rate. With the development of the 5G industry, the market demand for silicone resin coatings is increasingly diversified, requiring not only further improvement in material performance, but also consideration of cost-effectiveness, environmental friendliness and manufacturing process feasibility.

[0003] Among them, alkoxyl silicone resins are helpful to expand their application range in high-frequency communication and microelectronics due to their good processability of moisture curing under mild conditions. The improvement of the synthesis technology of alkoxyl silicone resins mainly focuses on improving their molecular structure and improving the matrix performance. By controlling the reaction conditions and using modification means, the molecular weight distribution and molecular topological structure of the resin can be further controlled, thereby being beneficial to optimizing the thermal stability and dielectric properties of the silicone resin material.

[0004] Chinese patent CN1283695C discloses a method for improving the heat resistance of silicone resin by using polyhedral oligomeric silsesquioxane. The organic silicone resin is prepared by using methyl alkoxysilane monomer as raw material. The modified silicone resin with certain heat resistance is prepared by adding 0.5-10% of oligomeric silsesquioxane based on the mass of the silicone resin. However, the preparation route of this method is complicated, the doping degree of oligomeric silsesquioxane is high, and the raw material cost is also high.

[0005] Chinese patent CN114133574A discloses a method for improving the mechanical strength of silicone resin by introducing bridged ring alkanes into the silicone resin main chain while maintaining good heat resistance and dielectric properties of the silicone resin. However, this method still has some deficiencies. The presence of a large number of benzene rings in the resin structure leads to an increase in the steric hindrance of the phenyl silicone resin, and the reaction conditions are harsh and not suitable for industrial production.

[0006] Chinese patent CN102887916A discloses an alkoxyl silicone resin intermediate and a preparation method thereof. The monomer source for synthesizing the alkoxyl silicone resin intermediate is organic chlorosilane. The resin can be applied to modify organic resins containing active hydroxyl functional groups. However, this preparation method produces a large amount of acidic by-products, has many post-processing steps, and has equipment corrosion problems in the production process, which does not meet the green environmental protection requirements.

[0007] Chinese patent CN103755960A discloses a heat-stable methylphenyl silicone resin and a preparation method thereof. The resin is not easy to dissolve in toluene and xylene, a large amount of toluene needs to be added as a solvent in the synthesis process, and the initial thermal decomposition temperature of the resin cured product is difficult to exceed 500 DEG C.

[0008] At present, there are few types of alkoxysilicone resins that can meet the demand of high-temperature-resistant low-dielectric silicone resin coating in China. The preparation methods of the alkoxysilicone resins disclosed in the existing patent documents still have the problems of complex reaction route, insufficient economy and environmental protection, and difficulty in batch preparation. Most of the alkoxysilicone resin coatings also have the problems of insufficient high-temperature-resistant stability, unclear dielectric performance, and unclear comprehensive performance, which seriously limit the use scenarios and application popularization of the silicone resin coating materials. Therefore, how to provide a simple, fast and green preparation method of high-performance low-viscosity alkoxyl-rich organosilicon resin is very crucial for optimizing the use performance of the silicone resin coating. SUMMARY

[0009] In view of the above problems existing in the prior art, the technical problems to be solved by the present application are to provide a preparation method of low-viscosity alkoxyl-rich hyperbranched organosilicon resin. The method is to make the hyperbranched organosilicon resin with a highly branched topological structure and rich in alkoxyl functional groups by selecting tri-functional siloxane monomers containing alkyl groups / aromatic groups and di-functional siloxane monomers containing alkyl groups / aromatic groups to undergo controllable hydrolysis and condensation reaction under the action of a catalyst. Another technical problem to be solved by the present application is to provide a low-viscosity alkoxyl-rich hyperbranched organosilicon resin prepared by the above method. The resin has the physical and chemical characteristics of low viscosity, high transparency and high activity, and can be further cured and formed by heating condensation or moisture dealcoholization condensation. The present application also solves a technical problem of providing the application of the above low-viscosity alkoxyl-rich hyperbranched organosilicon resin in high-temperature-resistant low-dielectric silicone resin coating.

[0010] In order to solve the above technical problems, the technical solutions adopted by the present application are as follows:

[0011] A preparation method of low-viscosity alkoxyl-rich hyperbranched organosilicon resin, which uses tri-functional siloxane monomers containing alkyl groups or aromatic groups as raw materials, and is prepared by hydrolysis nucleation, condensation growth, end-capping and purification treatment to obtain low-viscosity alkoxyl-rich hyperbranched organosilicon resin. The content of alkoxyl groups is not less than 3%, and the viscosity is not higher than 1000 mPa·s. The reaction formula is as follows:

[0012]

[0013] As preferred, the alkyl or aryl group containing tri-functional siloxane monomer is selected from one or more of methyltrimethoxysilane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, cyclohexyltrimethoxysilane, n-octyltrimethoxysilane, n-dodecyltrimethoxysilane, n-hexadecyltrimethoxysilane, methyltriethoxysilane, isobutyltriethoxysilane, n-hexyltriethoxysilane, cyclohexyltriethoxysilane, n-octyltriethoxysilane, n-dodecyltriethoxysilane, n-hexadecyltriethoxysilane, phenyltrimethoxysilane, naphthyltrimethoxysilane, biphenyltrimethoxysilane, phenyltriethoxysilane, naphthyltriethoxysilane, biphenyltriethoxysilane.

[0014] As preferred, the alkyl or aryl group containing tri-functional siloxane monomer is selected from one or more of methyltrimethoxysilane, phenyltrimethoxysilane.

[0015] The method for preparing the low viscosity alkoxyl group rich hyperbranched silicone resin comprises the following steps:

[0016] 1) mixing alkyl or aryl group containing tri-functional siloxane monomer and deionized water in a reactor, and hydrolyzing at room temperature for 3-5 hours;

[0017] 2) adding alkyl or aryl group containing di-functional siloxane monomer, deionized water and catalyst into the reaction system of step 1), and condensation growing at 80-90°C for 11-13 hours;

[0018] 3) adding alcohol end-capping agent and catalyst into the reaction system of step 2), and reacting at 115-125°C for 7-9 hours;

[0019] 4) distilling the solution after the end-capping reaction of step 3) under reduced pressure to obtain the low viscosity alkoxyl group rich hyperbranched silicone resin.

[0020] As preferred, in step 1), the molar ratio of alkyl or aryl group containing tri-functional siloxane monomer and deionized water is 1:0.1-3.

[0021] As preferred, in step 2), the molar ratio of alkyl or aryl group containing di-functional siloxane monomer, deionized water and catalyst is 1:0.1-3:0.001-0.1.

[0022] As preferred, in step 2), the alkyl or aryl group containing tri-functional siloxane monomer is selected from one or more of dimethyldimethoxysilane, methylphenyldimethoxysilane, diphenyldimethoxysilane, dimethyldiethoxysilane, methylphenyldiethoxysilane, diphenyldiethoxysilane.

[0023] The catalyst is selected from one or more of hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, glacial acetic acid, trifluoromethanesulfonic acid, p-methylbenzenesulfonic acid, ammonium chloride, potassium hydroxide, sodium hydroxide, aqueous ammonia, triethylamine, and tetramethylammonium hydroxide.

[0024] Preferably, in step 3), the molar ratio of the alkyl- or aryl-containing trifunctional siloxane monomer, the alcohol end-capping agent, and the catalyst is 1:0.1-10:0.01-0.1.

[0025] Preferably, in step 3), the alcohol end-capping agent is selected from one or more of methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, ethenol, and propenol.

[0026] The catalyst is selected from one or more of oxalic acid, glacial acetic acid, trifluoromethanesulfonic acid, and p-methylbenzenesulfonic acid.

[0027] The method for preparing the low-viscosity alkoxyl group-rich hyperbranched organosilicon resin.

[0028] The low-viscosity alkoxyl group-rich hyperbranched organosilicon resin is used in a high-temperature-resistant low-dielectric silicon resin coating.

[0029] Advantages: Compared with the prior art, the present application has the following advantages:

[0030] 1) The present application uses an alkyl- or aryl-containing trifunctional siloxane monomer and an alkyl- or aryl-containing difunctional siloxane monomer to undergo a controllable hydrolysis and polycondensation reaction under the action of a catalyst, thereby obtaining a hyperbranched organosilicon resin with a highly branched topological structure and rich in alkoxyl groups, which has the physical and chemical characteristics of low viscosity, high transparency, and high activity, and can be further cured and formed through heating condensation or moisture-induced dealcoholization condensation.

[0031] 2) The present application uses esterification end-capping reaction control to reduce the content of silicon hydroxyl groups, which is not conducive to storage, and the content of silicon hydroxyl groups is not higher than 1%; therefore, the alkoxyl group-rich hyperbranched organosilicon resin prepared can be stored for a long time in an ordinary environment, and the alkoxyl group content and viscosity range of the resin can be quantitatively controlled according to different application requirements.

[0032] 3) The low-viscosity alkoxyl group-rich hyperbranched organosilicon resin prepared by the present application can be used for the modification and reinforcement of special functional polymer materials and their composites, and after curing itself, it can form a high-temperature-resistant low-dielectric organosilicon transparent coating, and the coating preparation process is simple and controllable, suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The low-viscosity alkoxyl group-rich hyperbranched organosilicon resin prepared for Examples 1-7 is shown in the figure.

[0034] Figure 2 Physical picture of alkoxyl-containing silicone resin prepared for Comparative Example 1-2;

[0035] Figure 3 Infrared spectrum of low viscosity alkoxyl-rich hyperbranched silicone resin prepared for Example 1-7;

[0036] Figure 4 Physical picture of moisture cured sample of low viscosity alkoxyl-rich hyperbranched silicone resin prepared for Example 1, Example 7 at room temperature;

[0037] Figure 5 Thermogravimetric curve of low viscosity alkoxyl-rich hyperbranched silicone resin prepared for Example 1;

[0038] Figure 6 Thermogravimetric differential curve of low viscosity alkoxyl-rich hyperbranched silicone resin prepared for Example 1;

[0039] Figure 7 Physical picture of cured coating of low viscosity alkoxyl-rich hyperbranched silicone resin prepared for Example 1 under heating condition;

[0040] Figure 8 Dielectric constant and dielectric loss curve of cured sample of low viscosity alkoxyl-rich hyperbranched silicone resin prepared for Example 1;

[0041] Figure 9 Loss factor curve of cured sample of low viscosity alkoxyl-rich hyperbranched silicone resin prepared for Example 1. DETAILED DESCRIPTION

[0042] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described below in conjunction with specific examples. Unless otherwise specified, the technical means used in the following examples are all conventional means well known to those skilled in the art. If no specific conditions are indicated in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If no manufacturer of the reagent or instrument is indicated, it is a conventional product that can be obtained by commercial purchase.

[0043] The performance test methods used in the present application are as follows:

[0044] 1. Resin viscosity: a ROTAVIS type rotary viscometer (IKA Company, Germany) was used to test the viscosity of liquid silicone resin;

[0045] 2. Infrared spectrum: a Tensor II type FT-IR spectrometer (Bruker Company, Germany) was used for infrared test. The liquid sample was coated on a pressed KBr sample for test, and the test scanning range was 400-4000 cm -1 .

[0046] 3. Thermogravimetric analysis test: Thermogravimetric analysis was performed by using STA449F3 thermogravimetric-differential scanning calorimetry simultaneous analyzer (Netzche, Germany).

[0047] 4. Alkoxy content: The determination of siloxy content was performed by perchloric acid acetylation titration method.

[0048] 5. Silanol content: The determination of silanol content was performed by diisocyanate back titration method.

[0049] 6. Dielectric constant and dielectric loss: Dielectric test was performed by using Concept 80 broadband dielectric and impedance spectrometer (Novocontrol, Germany), and the surface of the solid test sample was previously treated by gold spraying.

[0050] Example 1

[0051] A method for preparing a low-viscosity alkoxyl-rich hyperbranched organosilicon resin, specifically comprising the following steps:

[0052] 1) 1362.2 g of methyltrimethoxysilane and 245 g of deionized water were added into a three-necked flask with stirring and condensation reflux device, and reacted at room temperature for 4 h;

[0053] 2) 1202.2 g of dimethyldimethoxysilane, 90 g of deionized water and 20 mL of 37% HCl solution were added into the reaction system of step 1), and reacted at 85°C for 12 h;

[0054] 3) 5.85 L of anhydrous ethanol was added into the reaction system of step 2), 10 mL of trifluoromethanesulfonic acid was added dropwise using a constant pressure dropping funnel, and the reaction system was heated to 120°C and then reacted for 8 h;

[0055] 4) The resin solution after reaction was distilled at 0.01 kPa and 85°C under reduced pressure to remove the solvent and small molecule monomers, and a low-viscosity alkoxyl-rich hyperbranched organosilicon resin was obtained.

[0056] Example 2

[0057] A method for preparing a low-viscosity alkoxyl-rich hyperbranched organosilicon resin, specifically comprising the following steps:

[0058] 1) 1226.0 g of methyltrimethoxysilane, 198.3 g of phenyltrimethoxysilane and 245 g of deionized water were added into a three-necked flask with stirring and condensation reflux device, and reacted at room temperature for 4 h;

[0059] 2) To the reaction system of step 1), 1082.0 g of dimethyldimethoxysilane, 189.3 g of methylphenyldimethoxysilane, 90 g of deionized water and 20 mL of HCl solution with a concentration of 37% were added, and the reaction was carried out at 85°C for 12 h;

[0060] 3) To the reaction system of step 2), 5.85 L of anhydrous ethanol was added, 10 mL of trifluoromethanesulfonic acid was added dropwise using a constant pressure dropping funnel, and the reaction system was heated to 120°C and then the reaction was continued for 8 h;

[0061] 4) The resin solution after the reaction was completed was distilled under reduced pressure at 0.01 kPa and 85°C to remove the solvent and small molecule monomers, and a low viscosity alkoxyl-rich hyperbranched silicone resin was obtained.

[0062] Example 3

[0063] A method for preparing a low viscosity alkoxyl-rich hyperbranched silicone resin, specifically comprising the following steps:

[0064] 1) A three-necked flask with stirring and condensation reflux device was added 953.5 g of methyltrimethoxysilane, 594.9 g of phenyltrimethoxysilane and 245 g of deionized water, and the reaction was carried out at room temperature for 4 h;

[0065] 2) To the reaction system of step 1), 841.5 g of dimethyldimethoxysilane, 567.9 g of methylphenyldimethoxysilane, 90 g of deionized water and 20 mL of HCl solution with a concentration of 37% were added, and the reaction was carried out at 85°C for 12 h;

[0066] 3) To the reaction system of step 2), 5.85 L of anhydrous ethanol was added, 10 mL of trifluoromethanesulfonic acid was added dropwise using a constant pressure dropping funnel, and the reaction system was heated to 120°C and then the reaction was continued for 8 h;

[0067] 4) The resin solution after the reaction was completed was distilled under reduced pressure at 0.01 kPa and 85°C to remove the solvent and small molecule monomers, and a low viscosity alkoxyl-rich hyperbranched silicone resin was obtained.

[0068] Example 4

[0069] A method for preparing a low viscosity alkoxyl-rich hyperbranched silicone resin, specifically comprising the following steps:

[0070] 1) A three-necked flask with stirring and condensation reflux device was added 953.5 g of methyltrimethoxysilane, 594.9 g of phenyltrimethoxysilane and 245 g of deionized water, and the reaction was carried out at room temperature for 4 h;

[0071] 2) To the reaction system of step 1), 601.1 g of dimethyldimethoxysilane, 946.5 g of methylphenyldimethoxysilane, 90 g of deionized water and 20 mL of HCl solution with a concentration of 37% are added, and the reaction is carried out at 85°C for 12 h;

[0072] 3) To the reaction system of step 2), 5.85 L of anhydrous ethanol is added, 10 mL of trifluoromethanesulfonic acid is added dropwise using a constant-pressure dropping funnel, and the reaction system is heated to 120°C and then the reaction is continued for 8 h;

[0073] 4) The resin solution after the reaction is completed is distilled under reduced pressure at 0.01 kPa and 85°C to remove the solvent and small molecule monomers, and a low-viscosity alkoxyl-rich hyperbranched silicone resin is obtained.

[0074] Example 5

[0075] A method for preparing a low-viscosity alkoxyl-rich hyperbranched silicone resin, specifically comprising the following steps:

[0076] 1) In a three-necked flask with stirring and condensation reflux device, 408.7 g of methyltrimethoxysilane, 1388.0 g of phenyltrimethoxysilane and 245 g of deionized water are added, and the reaction is carried out at room temperature for 4 h;

[0077] 2) To the reaction system of step 1), 360.7 g of dimethyldimethoxysilane, 1325.0 g of methylphenyldimethoxysilane, 90 g of deionized water and 20 mL of HCl solution with a concentration of 37% are added, and the reaction is carried out at 85°C for 12 h;

[0078] 3) To the reaction system of step 2), 5.85 L of anhydrous ethanol is added, 10 mL of trifluoromethanesulfonic acid is added dropwise using a constant-pressure dropping funnel, and the reaction system is heated to 120°C and then the reaction is continued for 8 h;

[0079] 4) The resin solution after the reaction is completed is distilled under reduced pressure at 0.01 kPa and 85°C to remove the solvent and small molecule monomers, and a low-viscosity alkoxyl-rich hyperbranched silicone resin is obtained.

[0080] Example 6

[0081] A method for preparing a low-viscosity alkoxyl-rich hyperbranched silicone resin, specifically comprising the following steps:

[0082] 1) In a three-necked flask with stirring and condensation reflux device, 408.7 g of methyltrimethoxysilane, 1388.0 g of phenyltrimethoxysilane and 245 g of deionized water are added, and the reaction is carried out at room temperature for 4 h;

[0083] 2) To the reaction system of step 1), 120.2 g of dimethyl dimethoxysilane, 1703.6 g of methyl phenyl dimethoxysilane, 90 g of deionized water and 20 mL of HCl solution with a concentration of 37% were added, and the reaction was carried out at 85°C for 12 h;

[0084] 3) To the reaction system of step 2), 5.85 L of anhydrous ethanol was added, 10 mL of trifluoromethanesulfonic acid was added dropwise using a constant pressure dropping funnel, and the reaction system was heated to 120°C and then the reaction was continued for 8 h;

[0085] 4) The resin solution after the reaction was completed was distilled under reduced pressure at 0.01 kPa and 85°C to remove the solvent and small molecule monomers, and a low viscosity alkoxyl-rich hyperbranched silicone resin was obtained.

[0086] Example 7

[0087] A method for preparing a low viscosity alkoxyl-rich hyperbranched silicone resin, specifically comprising the following steps:

[0088] 1) A three-necked flask with stirring and reflux condensation device was added 1982.9 g of phenyl trimethoxysilane and 245 g of deionized water, and the reaction was carried out at room temperature for 4 h;

[0089] 2) To the reaction system of step 1), 1892.9 g of methyl phenyl dimethoxysilane, 90 g of deionized water and 20 mL of HCl solution with a concentration of 37% were added, and the reaction was carried out at 85°C for 12 h;

[0090] 3) To the reaction system of step 2), 5.85 L of anhydrous ethanol was added, 10 mL of trifluoromethanesulfonic acid was added dropwise using a constant pressure dropping funnel, and the reaction system was heated to 120°C and then the reaction was continued for 8 h;

[0091] 4) The resin solution after the reaction was completed was distilled under reduced pressure at 0.01 kPa and 85°C to remove the solvent and small molecule monomers, and a low viscosity alkoxyl-rich hyperbranched silicone resin was obtained.

[0092] Comparative Example 1

[0093] 1) A three-necked flask with stirring and reflux condensation device was added 100 g of tetraethoxysilane, 31 g of hexamethyldisiloxane and 400 g of anhydrous ethanol, and the reaction was carried out at room temperature for 1 h;

[0094] 2) To the reaction system of step 1), 100 g of HCl solution with a concentration of 0.2 M was added, and after the dropwise addition was completed, the mechanical stirring was continued at room temperature for 1 h, and then the reaction system was gradually heated to 70°C and the reaction was continued for 3 h;

[0095] 3) To the reaction system of step 2), 200 g of toluene was added, and mechanical stirring was carried out at room temperature for 2 h, mechanical stirring was stopped, and standing was carried out for 2 h, liquid-liquid separation was carried out, and the upper layer of the extraction liquid was collected;

[0096] 4) The extraction liquid of step 3) was all poured into another flask, a potassium hydroxide solution with a concentration of 0.5 M was added dropwise, the pH value of the solution was adjusted to 8, an oil-water separator was connected, and the reaction system was heated to 85 ℃ and kept at this temperature for 3 h;

[0097] 5) The reaction system of step 4) was cooled to 60 ℃, sodium bicarbonate solid was added, and the pH value of the solution was adjusted to 6.5; then, filtration was carried out, and the filtrate was distilled under reduced pressure at 0.01 kPa and 85 ℃ to obtain a siloxane resin containing an alkoxy group. As shown in Table 1, the resin prepared in Comparative Example 1 was a milky white viscous liquid. Figure 2

[0098] Comparative Example 2

[0099] 1) A three-necked flask with stirring and reflux condensation device was added with 110 g of methyltrimethoxysilane, 394 g of dimethyldiethoxysilane, 780 g of phenyltriethoxysilane and 2.5 g of lead naphthenate catalyst, and stirring was carried out at room temperature for 1 h, and then the temperature was increased to 100 ℃;

[0100] 2) Deionized water was added dropwise to the reaction system of step 1) to carry out quantitative hydrolysis, and the dropping was completed in 3 h;

[0101] 3) After the reaction system of step 2) was continuously reacted for 30 min, the system was vacuumized to 0.01 kPa and gradually heated to 120 ℃ to remove small molecular impurities such as ethanol;

[0102] 4) After the reaction system of step 3) was observed without liquid dropping, the product was immediately discharged to obtain a white solid siloxane resin.

[0103] The viscosity and alkoxy and hydroxyl contents of the samples of the siloxane resins prepared in the above Examples 1-7 and Comparative Examples 1-2 were tested, and the test results are shown in Table 1.

[0104] Table 1 Viscosity and functional group content of the samples of the siloxane resins prepared in Examples 1-7 and Comparative Examples 1-2

[0105] Resin viscosity (mPa-s) Alkoxy content (%) Silanol content (%) Example 1 300 15.9 0.07 Example 2 420 13.6 0.07 Example 3 560 12.4 0.12 Example 4 620 10.5 0.14 Example 5 710 8.9 0.23 Example 6 810 7.3 0.29 Example 7 960 3.6 0.39 Comparative Example 1 193000 1.9 3.42 Comparative Example 2 White powder 7.0 1.52

[0106] As shown in Table 1, the hyperbranched siloxane resin prepared by the hydrolysis nucleation, condensation growth, end capping and purification treatment route has a relatively high alkoxy content and a relatively low silicon hydroxyl content, compared with Comparative Examples 1-2, the alkoxy-rich hyperbranched siloxane resin prepared in Examples 1-7 has a lower viscosity, an alkoxy content not less than 3.5% and a silicon hydroxyl content not higher than 0.5%. ​

[0107] As can be seen from Figure 1 and Figure 2 The rich-alkoxy hyperbranched silicone resin prepared in the present application (Examples 1-7) is in the form of colorless liquid. Compared with Comparative Examples 1-2, the rich-alkoxy hyperbranched silicone resin prepared in the present application (Examples 1-7) has better transparency and lower viscosity.

[0108] As can be seen from Figure 3 The rich-alkoxy hyperbranched silicone resin prepared in the present application (Examples 1-7) has typical siloxy infrared characteristic peaks at 2972 cm -1 , proving that the alkoxyl groups are distributed in the silicone resin skeleton structure.

[0109] As can be seen from Figure 4 The rich-alkoxy hyperbranched silicone resin prepared in the present application (Examples 1 and 7) can be cross-linked and cured to form a hard coating after being placed in a room temperature environment (50% RH) for 12 h, and the coating can withstand high-temperature burning treatment (outer flame temperature ≥ 800℃) of an alcohol torch.

[0110] As can be seen from Figure 5 The cured product of the rich-alkoxy hyperbranched silicone resin prepared in the present application (Example 1) has good thermal stability under nitrogen and air atmospheres, and the initial thermal decomposition temperature is higher than 500℃.

[0111] As can be seen from Figure 6 The cured product of the rich-alkoxy hyperbranched silicone resin prepared in the present application (Example 1) has good thermal stability under nitrogen and air atmospheres, and the maximum thermal weight loss temperature is higher than 550℃.

[0112] As can be seen from Figure 7 The rich-alkoxy hyperbranched silicone resin prepared in the present application (Example 1) has heat-curable cross-linking properties, and a transparent and solid heat-curable organic silicon coating can be prepared after programmed temperature rising (100℃×2h→140℃×2h→180℃×2h→220℃×4h), and can be firmly attached to the surface of a carbon fiber composite material.

[0113] As can be seen from Figure 8 The heat-cured product of the rich-alkoxy hyperbranched silicone resin prepared in the present application (Example 1) has low dielectric characteristics of a silicone resin, and the dielectric constant is not higher than 3.0 and the dielectric loss is about 0.01 when the frequency is 1k Hz.

[0114] As can be seen from Figure 9 The heat-cured product of the rich-alkoxy hyperbranched silicone resin prepared in the present application (Example 1) has low dielectric characteristics of a silicone resin, and the loss factor is about 36.9×10 -4 when the frequency is 1k Hz.

[0115] Table 2 Test results of the cured samples of the hyperbranched silicone resins prepared in Examples 1-7 and Comparative Examples 1-2

[0116]

[0117]

[0118] As can be seen from Table 2, the thermal cured products of the alkoxyl-rich hyperbranched silicone resins prepared in Examples 1-7 have better thermal stability than the thermal cured products of Comparative Examples 1-2, with the initial thermal decomposition temperature in air atmosphere being higher than 400℃, and the initial thermal decomposition temperature of the samples corresponding to Examples 1 and 2 being higher than 500℃. In addition, the thermal cured products of Examples 1-7 exhibit lower dielectric constant and dielectric loss, and excellent dielectric performance, and are expected to be applied in the field of 5G related materials.

[0119] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a low-viscosity, alkoxy-rich, hyperbranched organosilicon resin, characterized in that, Using trifunctional siloxane monomers containing alkyl or aromatic groups as raw materials, a low-viscosity alkoxy-rich hyperbranched organosilicon resin is prepared through hydrolysis nucleation, condensation growth, end-capping, and purification. The alkoxy content is not less than 3%, and the viscosity is not higher than 1000 mPa·s. The specific steps include: 1) Add trifunctional siloxane monomers containing alkyl or aromatic groups and deionized water to the reactor and mix them. Then, hydrolyze the mixture at room temperature for 3-5 hours. 2) Add a difunctional siloxane monomer containing alkyl or aromatic groups, deionized water and catalyst to the reaction system of step 1), mix and perform condensation growth reaction at 80~90℃ for 11~13h; 3) Add alcohol-based end-capping agent and catalyst to the reaction system of step 2), and react at 115~125℃ for 7~9h; 4) Distill the solution after the end-capping reaction in step 3) under reduced pressure to obtain a low-viscosity alkoxy-rich hyperbranched organosilicon resin.

2. The method for preparing low-viscosity alkoxy-rich hyperbranched organosilicon resin according to claim 1, characterized in that, The alkyl or aromatic trifunctional siloxane monomer is selected from one or more of methyltrimethoxysilane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, cyclohexyltrimethoxysilane, n-octyltrimethoxysilane, n-dodecyltrimethoxysilane, n-hexadecyltrimethoxysilane, methyltriethoxysilane, isobutyltriethoxysilane, n-hexyltriethoxysilane, cyclohexyltriethoxysilane, n-octyltriethoxysilane, n-dodecyltriethoxysilane, n-hexadecyltriethoxysilane, phenyltrimethoxysilane, naphthyltrimethoxysilane, biphenyltrimethoxysilane, phenyltriethoxysilane, naphthyltriethoxysilane, and biphenyltriethoxysilane.

3. The method for preparing low-viscosity alkoxy-rich hyperbranched organosilicon resin according to claim 1, characterized in that, In step 1), the molar ratio of the trifunctional siloxane monomer containing alkyl or aromatic groups to deionized water is 1:0.1~3.

4. The method for preparing low-viscosity alkoxy-rich hyperbranched organosilicon resin according to claim 1, characterized in that, In step 2), the molar ratio of the trifunctional siloxane monomer containing alkyl or aromatic groups, the difunctional siloxane monomer containing alkyl or aromatic groups, deionized water, and the catalyst is 1:0~3:0.1~5:0.001~0.

1.

5. The method for preparing low-viscosity alkoxy-rich hyperbranched organosilicon resin according to claim 1, characterized in that, In step 2), the alkyl or aromatic difunctional siloxane monomer is selected from one or more of dimethyldimethoxysilane, methylphenyldimethoxysilane, diphenyldimethoxysilane, dimethyldiethoxysilane, methylphenyldiethoxysilane, and diphenyldiethoxysilane. The catalyst is selected from one or more of the following: hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, glacial acetic acid, trifluoromethanesulfonic acid, p-toluenesulfonic acid, ammonium chloride, potassium hydroxide, sodium hydroxide, ammonia, triethylamine, and tetramethylammonium hydroxide.

6. The method for preparing low-viscosity alkoxy-rich hyperbranched organosilicon resin according to claim 1, characterized in that, In step 3), the molar ratio of the trifunctional siloxane monomer containing alkyl or aromatic groups, the alcohol end-capping agent, and the catalyst is 1:0.1~10:0.01~0.

1.

7. The method for preparing low-viscosity alkoxy-rich hyperbranched organosilicon resin according to claim 1, characterized in that, In step 3), the alcohol-based end-capping agent is selected from one or more of methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, vinyl alcohol, and allyl alcohol. The catalyst is selected from one or more of oxalic acid, glacial acetic acid, trifluoromethanesulfonic acid, and p-toluenesulfonic acid.

8. The low-viscosity alkoxy-rich hyperbranched organosilicon resin obtained by the preparation method according to any one of claims 1 to 7.

9. The application of the low-viscosity alkoxy-rich hyperbranched organosilicon resin according to claim 8 in high-temperature resistant, low-dielectric silicone resin coatings.

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