Preparation method of high-heat-resistance organic silicon resin

Abstract

The invention discloses a preparation method of high-heat-resistance organic silicon resin, and belongs to the technical field of organic silicon resin production, a siloxane ring body and a hydrogen-containing double end socket are subjected to ring opening polymerization under acid catalysis, and a linear end hydrogen D prepolymer is copolymerized; carrying out hydrolytic condensation on trifunctional alkoxy silane to prepare a hydroxyl-terminated T prepolymer; mixing the methyl phenyl silicone resin and the methyl phenyl silicone resin, adding a selective catalyst to carry out block copolymerization reaction to form an intermediate, and finally carrying out high-temperature polycondensation reaction under the action of a condensation catalyst to obtain the methyl phenyl silicone resin. A high-selectivity dehydrogenation coupling catalyst is taken as a core to mediate a puzzle type copolymerization reaction of a D prepolymer and a T prepolymer with different functional groups, so that high-degree-of-freedom fine regulation and control of a resin structure are realized from the bottom layer, the structural defects of the resin are greatly reduced, and the heat resistance of the resin is improved; zero emission is basically realized, a main byproduct is methanol which can be recycled, acid-containing wastewater is not generated, and the process is simple.

Description

Technical Field

[0001] The invention relates to the technical field of organosilicon resin production, and in particular to a method for preparing a highly heat-resistant organosilicon resin. Background Art

[0002] Silicone polymers are polymers that contain elemental silicon in their molecular structure and have organic groups attached to silicon atoms. Polysiloxanes with repeated Si-O bonds as the main chain and organic groups attached to silicon atoms are the main structural form of silicone polymers. Generally, silicone polymer materials with three or more hydrolyzable functional groups on silicon atoms in the molecule are called silicone resins. Silicone resins are a type of thermosetting polysiloxane system with a highly cross-linked structure.

[0003] At present, there are many varieties of silicone resins, mainly methyl silicone resin, phenyl silicone resin, methylphenyl silicone resin, MQ silicone resin, emulsion silicone resin, powdered silicone resin and addition silicone resin, among which methylphenyl silicone resin is widely used in aerospace, mechanical electronics, construction and other fields due to its excellent high and low temperature resistance, radiation resistance and electrical insulation performance. One of the biggest uses of this material is the preparation of silicone coatings, especially the preparation of special coatings to meet the special requirements of the military industry. Due to the introduction of phenyl silicon oxygen chain segments, methylphenyl silicone resin is significantly superior to methyl silicone resin in terms of thermal elasticity, mechanical properties, adhesion, gloss and compatibility with organic and inorganic fillers. It can be widely used as high temperature resistant insulating paint, high temperature resistant coating, high temperature resistant adhesive, high temperature resistant molding packaging material, ablative material, ladder polymer and silicone resin micropowder and other products. It is the largest and most widely used variety of silicone resin.

[0004] At present, methylphenyl silicone resin is mainly prepared by direct hydrolysis and condensation of chlorosilane or alkoxysilane. Chlorosilane route: The hydrolysis process produces a large amount of hydrogen chloride, which is highly corrosive. The product must be washed with water many times, the process is long, and the wastewater produced is difficult to treat; the hydrolysis and condensation activity of chlorosilane is too high, the product structure is difficult to control, and defects are easy to occur. Alkoxysilane route: The activity of alkoxy monomers varies greatly, the product structure is poorly uniform, and alkoxy groups are easily left, resulting in poor polymer performance. Summary of the invention

[0005] In view of the above-mentioned defects in the prior art, the present invention provides a method for preparing a high heat-resistant silicone resin, which does not use chlorosilane, thereby solving the problem of hydrogen chloride treatment; does not use low-activity difunctional alkoxysilane, thereby avoiding the problem of performance degradation caused by alkoxy residues; and adopts a method of first preparing a hydrogen-terminated D-type prepolymer and a hydroxyl-terminated T-type prepolymer, and then cross-coupling block copolymerization, thereby precisely controlling the polymer structure and solving the problems of structural defects and poor uniformity.

[0006] The objective of the present invention is achieved through the following technical solutions: A method for preparing a highly heat-resistant silicone resin comprises the following steps: Step 1, preparation of D prepolymer: after adding octaphenyl ring body to the polymerization kettle, the feeding needs to be stopped, and after the oil temperature rises to 90-120°C, vacuum drying is carried out for 30-60min, and then octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid are added in sequence under the protection of dry nitrogen; stirring is started, and after the internal temperature reaches 80-100°C, a ring-opening polymerization reaction is carried out for 0.5-2h, and a sample is taken to test the viscosity. When the viscosity reaches 20-50mPa·s, the solid acid catalyst is filtered out and the short-path distiller is preheated to 150-180°C, and the internal pressure is not higher than 100Pa, and the polymer is slowly passed through the short-path distiller to remove unreacted monomers and other low molecular weight compounds, so as to obtain the preparation of D prepolymer; Step 2, preparation of T prepolymer: add phenyltrimethoxysilane, methyltrimethoxysilane and toluene to the silicon prepolymer kettle in sequence; start stirring; add deionized water and hydrochloric acid to the high-level tank; close the extraction valve, open the vent valve, adjust the valve to the reflux state, turn on the condenser cooling water; turn on the jacket cooling water, slowly add acid water to the reaction system through the flow meter, control the dropping speed, and finish the dropping in 0.5h. The internal temperature is controlled at 40-50℃; after the acid water is added, steam is used for heating and the initial temperature is set at 50-55℃ to avoid material rushing; the material digital display temperature rises to 55-6 At 0℃, turn down the steam opening, the digital display temperature of the material rises to 67-69℃ and starts to reflux, keep it for 2h, adjust the valve to the water separation state, evaporate methanol and water, start timing when the system is transparent, continue the reaction for 0.3-0.8h, stop heating, pass cooling water through the jacket to cool down, cool down to below 40℃ after the reaction, turn off the cooling water, add Na2CO3 to neutralize the catalyst, dry it with activated 4A molecular sieve in a closed container at 20-40℃ for 12-36h, filter it with filter cloth under the protection of dry nitrogen until there is no visible suspended impurities in the transparent solution, and obtain T prepolymer; Step 3, add the D-type prepolymer, T-type prepolymer and borane catalyst to a nitrogen-protected and fully dried copolymerization kettle, react at 25-40°C for 48-96h, gradually heat to 110°C, keep warm for 0.5-1h, and obtain a low molecular weight intermediate polymer by block polymerization; after cooling to below 50°C, add xylene for dilution, add a condensation catalyst, heat to reflux temperature, reflux with water, and carry out polycondensation reaction, control the internal temperature at 125-135°C, polycondense for 6-16h, and cool to obtain methylphenyl silicone resin after the viscosity reaches 140mPa·s.

[0007] Preferably, in the step 1, before adding octaphenylcyclotetrasiloxane, check and make sure that the bottom valve of the polymerization kettle is in a closed state, the vent valve is in an open state, turn on the heating power of the polymerization kettle, and set the oil temperature to 140-170°C.

[0008] Preferably, in the step 1, the mass ratio of octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid is 100:40-48:8-16:1-6.

[0009] Preferably, in step 1, the solid acid can be any one of cation exchange resin, BF3 / Al2O3, ZSM-5 molecular sieve, Y molecular sieve, H3PW12O40, SO42- / ZrO2, and WO3 / ZrO2.

[0010] Preferably, in the step 1, octamethylcyclotetrasiloxane is added from the dehydration kettle to the polymerization kettle using a metering pump; the stirring speed is 150-300 r / min.

[0011] Preferably, in the step 2, before adding phenyltrimethoxysilane, check and confirm that the bottom valve of the silicon prepolymer kettle is closed, close the vent valve, and open the extraction valve; the stirring speed is 200-600r / min; the condenser uses a disc condenser, the cooling water temperature is not higher than 25°C, and the maximum flow rate is not less than 10 m 3 / h; the temperature of steam is not less than 135℃, the pressure is not less than 2.13Mpa, and the flow rate is not less than 1t / h; the heating rate is 0.5-1℃ / min; the purity of Na2CO3 is not less than 99%, and the particle size is between 0.08mm-0.15mm.

[0012] Preferably, in step 2, the mass ratio of phenyltrimethoxysilane, methyltrimethoxysilane, toluene, deionized water and hydrochloric acid is 100:250-300:300-400:200-250:0.05-0.5.

[0013] Preferably, in step 3, the mass ratio of the D-type prepolymer, the T-type prepolymer, the borane catalyst, the xylene, and the condensation catalyst is 100:80-160:0.1-0.5:60-300:0.1-0.5.

[0014] Preferably, the condensation catalyst is a dehydrogenation coupling catalyst, and the dehydrogenation coupling catalyst is any one of chloroplatinic acid, platinum nanoparticles, metal hydride, Custer platinum catalyst, BF3, and B(C6F5)3.

[0015] Preferably, in step 3, the heating rate is 0.7-0.9°C / min when gradually heating up; xylene is added through the high-level tank for dilution; the temperature is cooled down to below 40°C, and the cooling rate is not less than 3°C / min. (Which is more important in the preparation method, the process conditions or the composition and proportion of each component) The beneficial effects of this technical solution are as follows: 1. The present invention provides a method for preparing a high heat-resistant organic silicone resin, wherein a siloxane ring body and a hydrogen-containing double end are subjected to ring-opening polymerization under acid catalysis to copolymerize into a linear hydrogen-terminated D prepolymer; a trifunctional alkoxysilane is hydrolyzed and condensed to prepare a hydroxy-terminated T prepolymer; the two are then mixed, a selective catalyst is added to carry out a block copolymerization reaction to form an intermediate, and finally a high-temperature polycondensation reaction is carried out under the action of a condensation catalyst to obtain a methylphenyl silicone resin.

[0016] 2. The present invention provides a method for preparing a high heat-resistant silicone resin, which takes a highly selective dehydrogenation coupling catalyst as the core, mediates the "jigsaw puzzle" copolymerization reaction of heterofunctional group D prepolymer and T prepolymer, realizes high-degree-of-freedom fine regulation of the resin structure from the bottom layer, greatly reduces structural defects such as low-activity hydroxyl residues and large steric substituted groups in the resin, and improves the heat resistance of the resin (in an air atmosphere, the 10% weight loss temperature is not less than 550°C, and the weight retention rate at 1000°C is not less than 52%); basically achieves "zero emission", the main by-product is methanol, which can be recycled, does not produce acid-containing wastewater, and the process is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a preparation flow chart of the present invention; Figure 2 The typical TGA spectrum of the high heat-resistant silicone resin obtained in Example 6 of the present invention. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto.

[0019] Example 1 The present invention adopts Figure 1 The preparation process shown is a method for preparing a high heat-resistant silicone resin, comprising the following steps: Step 1, preparation of D prepolymer: after adding octaphenyl ring body to the polymerization kettle, the feeding needs to be stopped, and after the oil temperature rises to 90°C, vacuum drying is carried out for 30 minutes, and then octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid are added in sequence under the protection of dry nitrogen; stirring is started, and after the internal temperature reaches 80°C, a ring-opening polymerization reaction is carried out for 0.5h, and a sample is taken to test the viscosity. When the viscosity reaches 20mPa·s, the solid acid catalyst is filtered out and removed, and the short-path distiller is preheated to 150°C, and the internal pressure is 95Pa, and the polymer is slowly passed through the short-path distiller to remove unreacted monomers and other low molecular weight compounds, so as to obtain the preparation of D prepolymer; Step 2, preparation of T prepolymer: add phenyltrimethoxysilane, methyltrimethoxysilane and toluene to the silicon prepolymer kettle in turn; start stirring; add deionized water and hydrochloric acid to the high-level tank; close the extraction valve, open the vent valve, adjust the valve to the reflux state, turn on the condenser cooling water; turn on the jacket cooling water, slowly add acid water to the reaction system through the flow meter, control the dropping speed, and finish the dropping in 0.5h, and control the internal temperature at 40℃; after the acid water is added, steam is used for heating and the initial temperature is set at 50℃ to avoid material rushing; the material digital display temperature When the temperature rises to 55°C, the steam opening is turned down, and the digital display temperature of the material rises to 67°C and starts to reflux, which is maintained for 2 hours. The valve is adjusted to the water separation state, methanol and water are evaporated, and the timing is started when the system is transparent. The reaction is continued for 0.3 hours, and the heating is stopped. The jacket is cooled with cooling water. After the reaction is completed, the temperature is lowered to 35°C, and the cooling water is turned off. Na2CO3 is added to neutralize the catalyst, and the product is dried with an activated 4A molecular sieve in a closed container at 20°C for 12 hours. The product is filtered with a filter cloth under the protection of dry nitrogen until there is no visible suspended impurities in the transparent solution, and a T prepolymer is obtained; Step 3, add the D-type prepolymer, T-type prepolymer and borane catalyst to a nitrogen-protected and fully dried copolymerization kettle, react at 25°C for 48 hours, gradually heat to 110°C, keep warm for 0.5 hours, and obtain a low molecular weight intermediate polymer by block polymerization; after cooling to 45°C, add xylene for dilution, add a condensation catalyst, heat to reflux temperature, reflux with water, and carry out polycondensation reaction, control the internal temperature at 125°C, polycondense for 6 hours, and cool down to obtain methylphenyl silicone resin after the viscosity reaches 140mPa·s.

[0020] Wherein, in the step 1, before adding octaphenylcyclotetrasiloxane, check and make sure that the bottom valve of the polymerization kettle is in a closed state, the vent valve is in an open state, turn on the heating power of the polymerization kettle, and set the oil temperature to 140°C.

[0021] Wherein, in the step 1, the mass ratio of octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid is 100:40:8:1.

[0022] Wherein, in the step 1, the solid acid may be a cation exchange resin.

[0023] Wherein, in the step 1, octamethylcyclotetrasiloxane is added from the dehydration kettle to the polymerization kettle using a metering pump; the stirring speed is 150r / min.

[0024] Wherein, in the step 2, before adding phenyltrimethoxysilane, check and make sure that the bottom valve of the silicon prepolymer kettle is closed, close the vent valve, and open the extraction valve; the stirring speed is 200r / min; the condenser uses a disc condenser, the cooling water temperature is 25°C, and the maximum flow rate is 10 m 3 / h; the steam temperature is 135℃, the pressure is 2.13Mpa, and the flow rate is 1t / h; the heating rate is 0.5℃ / min; the purity of Na2CO3 is 99% and the particle size is 0.08mm.

[0025] Wherein, in the step 2, the mass ratio of phenyltrimethoxysilane, methyltrimethoxysilane, toluene, deionized water and hydrochloric acid is 100:250:300:200:0.05.

[0026] Wherein, in the step three, the mass ratio of the D-type prepolymer, the T-type prepolymer, the borane catalyst, the xylene, and the condensation catalyst is 100:80:0.1:60:0.1.

[0027] Wherein, the condensation catalyst is a dehydrogenation coupling catalyst, and the dehydrogenation coupling catalyst is chloroplatinic acid.

[0028] Wherein, in the step three, the heating rate is 0.7°C / min when gradually heating up; xylene is added through the high-level tank for dilution; the temperature is cooled down to 35°C, and the cooling rate is 3°C / min.

[0029] Example 2 A method for preparing a highly heat-resistant silicone resin comprises the following steps: Step 1, preparation of D prepolymer: after adding octaphenyl ring body to the polymerization kettle, the feeding needs to be stopped, and after the oil temperature rises to 105°C, vacuum drying is carried out for 45 minutes, and then octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid are added in sequence under the protection of dry nitrogen; stirring is started, and after the internal temperature reaches 90°C, a ring-opening polymerization reaction is carried out for 1.25 hours, and a sample is taken to test the viscosity. When the viscosity reaches 35mPa·s, the solid acid catalyst is filtered out, and the short-path distiller is preheated to 165°C, and the internal pressure is 95Pa. The polymer is slowly passed through the short-path distiller to remove unreacted monomers and other low molecular weight compounds, and the D prepolymer is prepared; Step 2, preparation of T prepolymer: add phenyltrimethoxysilane, methyltrimethoxysilane and toluene to the silicon prepolymer kettle in turn; start stirring; add deionized water and hydrochloric acid to the high-level tank; close the extraction valve, open the vent valve, adjust the valve to the reflux state, turn on the condenser cooling water; turn on the jacket cooling water, slowly add acid water to the reaction system through the flow meter, control the dropping speed, and finish dropping in 0.5h, and control the internal temperature at 45°C; after the acid water is added, steam is used for heating and the initial temperature is set at 52.5°C to avoid material rushing; the material digital display temperature When the temperature rises to 57.5℃, the steam opening is turned down, and the digital display temperature of the material rises to 68℃ and starts to reflux, which is maintained for 2h. The valve is adjusted to the water separation state, methanol and water are evaporated, and the timing is started when the system is transparent. The reaction is continued for 0.55h, and the heating is stopped. The jacket is cooled with cooling water. After the reaction is completed, the temperature is lowered to 35℃, and the cooling water is turned off. Na2CO3 is added to neutralize the catalyst, and the solution is dried with activated 4A molecular sieves in a closed container at 30℃ for 24h. The solution is filtered with filter cloth under the protection of dry nitrogen until there is no visible suspended impurities in the transparent solution to obtain T prepolymer; Step 3, add the D-type prepolymer, T-type prepolymer and borane catalyst to a nitrogen-protected and fully dried copolymerization kettle, react at 32.5°C for 72 hours, gradually heat to 110°C, keep warm for 0.75 hours, and obtain a low molecular weight intermediate polymer by block polymerization; after cooling to 45°C, add xylene for dilution, add a condensation catalyst, heat to reflux temperature, reflux with water, and carry out polycondensation reaction, control the internal temperature at 130°C, polycondense for 11 hours, and cool down to obtain methylphenyl silicone resin after the viscosity reaches 140mPa·s.

[0030] Wherein, in the step 1, before adding octaphenylcyclotetrasiloxane, check and make sure that the bottom valve of the polymerization kettle is in a closed state, the vent valve is in an open state, turn on the heating power of the polymerization kettle, and set the oil temperature to 155°C.

[0031] Wherein, in the step 1, the mass ratio of octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid is 100:44:12:3.5.

[0032] Wherein, in the step 1, the solid acid may be BF3 / Al2O3.

[0033] Wherein, in the step 1, octamethylcyclotetrasiloxane is added from the dehydration kettle to the polymerization kettle using a metering pump; the stirring speed is 225r / min.

[0034] Wherein, in the step 2, before adding phenyltrimethoxysilane, check and make sure that the bottom valve of the silicon prepolymer kettle is closed, close the vent valve, and open the extraction valve; the stirring speed is 400r / min; the condenser uses a disc condenser, the cooling water temperature is 25°C, and the maximum flow rate is 10 m 3 / h; the steam temperature is 135℃, the pressure is 2.13Mpa, and the flow rate is 1t / h; the heating rate is 0.75℃ / min; the purity of Na2CO3 is 99% and the particle size is 0.11mm.

[0035] Wherein, in the step 2, the mass ratio of phenyltrimethoxysilane, methyltrimethoxysilane, toluene, deionized water and hydrochloric acid is 100:275:350:225:0.225.

[0036] Wherein, in the step three, the mass ratio of the D-type prepolymer, the T-type prepolymer, the borane catalyst, the xylene, and the condensation catalyst is 100:120:0.3:180:0.3.

[0037] Wherein, the condensation catalyst is a dehydrogenation coupling catalyst, and the dehydrogenation coupling catalyst is platinum-type nanoparticles.

[0038] Wherein, in the step three, the heating rate is 0.8°C / min when gradually heating up; xylene is added through the high-level tank for dilution; the temperature is cooled down to 35°C, and the cooling rate is 3°C / min.

[0039] Example 3 A method for preparing a highly heat-resistant silicone resin comprises the following steps: Step 1, preparation of D prepolymer: after adding octaphenyl ring body to the polymerization kettle, the feeding needs to be stopped, and after the oil temperature rises to 120°C, vacuum drying is carried out for 60 minutes, and then octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid are added in sequence under the protection of dry nitrogen; stirring is started, and after the internal temperature reaches 100°C, a ring-opening polymerization reaction is carried out for 2 hours, and a sample is taken to test the viscosity. When the viscosity reaches 50mPa·s, the solid acid catalyst is filtered out and removed, and the short-path distiller is preheated to 180°C, and the internal pressure is 95Pa, and the polymer is slowly passed through the short-path distiller to remove unreacted monomers and other low molecular weight compounds, so as to obtain the preparation of D prepolymer; Step 2, preparation of T prepolymer: add phenyltrimethoxysilane, methyltrimethoxysilane and toluene to the silicon prepolymer kettle in sequence; start stirring; add deionized water and hydrochloric acid to the high-level tank; close the extraction valve, open the vent valve, adjust the valve to the reflux state, turn on the condenser cooling water; turn on the jacket cooling water, slowly add acid water to the reaction system through the flow meter, control the dropping speed, and finish dropping in 0.5h, and control the internal temperature at 50℃; after the acid water is added, steam is used for heating and the initial temperature is set at 55℃ to avoid material rushing; the material digital display temperature When the temperature rises to 60°C, the steam opening is turned down, and the digital display temperature of the material rises to 69°C and starts to reflux, which is maintained for 2 hours. The valve is adjusted to the water separation state, methanol and water are evaporated, and the timing is started when the system is transparent. The reaction is continued for 0.8 hours, and the heating is stopped. The jacket is cooled with cooling water. After the reaction is completed, the temperature is lowered to 35°C, and the cooling water is turned off. Na2CO3 is added to neutralize the catalyst, and the product is dried with an activated 4A molecular sieve in a closed container at 40°C for 36 hours. The product is filtered with a filter cloth under the protection of dry nitrogen until there is no visible suspended impurities in the transparent solution, and a T prepolymer is obtained; Step 3, add the D-type prepolymer, T-type prepolymer and borane catalyst to a nitrogen-protected and fully dried copolymerization kettle, react at 40°C for 96 hours, gradually heat to 110°C, keep warm for 1 hour, and obtain a low molecular weight intermediate polymer by block polymerization; after cooling to 45°C, add xylene for dilution, add a condensation catalyst, heat to reflux temperature, reflux with water, and carry out condensation reaction, control the internal temperature at 135°C, condense for 16 hours, and cool down to obtain methylphenyl silicone resin after the viscosity reaches 140mPa·s.

[0040] Wherein, in the step 1, before adding octaphenylcyclotetrasiloxane, check and make sure that the bottom valve of the polymerization kettle is in a closed state, the vent valve is in an open state, turn on the heating power of the polymerization kettle, and set the oil temperature to 155°C.

[0041] Wherein, in the step 1, the mass ratio of octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid is 100:48:16:6.

[0042] Wherein, in the step 1, the solid acid may be a ZSM-5 molecular sieve.

[0043] Wherein, in the step 1, octamethylcyclotetrasiloxane is added from the dehydration kettle to the polymerization kettle using a metering pump; the stirring speed is 300r / min.

[0044] Wherein, in the step 2, before adding phenyltrimethoxysilane, check and make sure that the bottom valve of the silicon prepolymer kettle is closed, close the vent valve, and open the extraction valve; the stirring speed is 600r / min; the condenser uses a disc condenser, the cooling water temperature is 25°C, and the maximum flow rate is 10 m 3 / h; the steam temperature is 135℃, the pressure is 2.13Mpa, and the flow rate is 1t / h; the heating rate is 1℃ / min; the purity of Na2CO3 is 99.5%, and the particle size is 0.15mm.

[0045] Wherein, in the step 2, the mass ratio of phenyltrimethoxysilane, methyltrimethoxysilane, toluene, deionized water and hydrochloric acid is 100:300:400:250:0.5.

[0046] Wherein, in the step three, the mass ratio of D-type prepolymer, T-type prepolymer, borane catalyst, xylene and condensation catalyst is 100:160:0.5:300:0.5.

[0047] Wherein, the condensation catalyst is a dehydrogenation coupling catalyst, and the dehydrogenation coupling catalyst is a metal hydride.

[0048] Wherein, in the step three, the heating rate is 0.9°C / min when gradually heating up; xylene is added through the high-level tank for dilution; the temperature is cooled down to 35°C, and the cooling rate is 3°C / min.

[0049] Example 4 The difference between this embodiment and embodiment 2 is that in step 1, the solid acid can be Y molecular sieve.

[0050] Wherein, the condensation catalyst is a dehydrogenation coupling catalyst, and the dehydrogenation coupling catalyst is a Custer platinum catalyst.

[0051] Example 5 The difference between this embodiment and embodiment 2 is that in step 1, the solid acid can be H3PW12O40.

[0052] Wherein, the condensation catalyst is a dehydrogenation coupling catalyst, and the dehydrogenation coupling catalyst is BF3.

[0053] Example 6 The difference between this embodiment and embodiment 2 is that in step 1, the solid acid may be SO42- / ZrO2.

[0054] Wherein, the condensation catalyst is a dehydrogenation coupling catalyst, and the dehydrogenation coupling catalyst is B(C6F5)3.

[0055] Example 7 The difference between this embodiment and embodiment 2 is that in step 1, the solid acid may be SO42- / ZrO2.

[0056] Example 8 The difference between this embodiment and embodiment 2 is that in step 1, the solid acid may be WO3 / ZrO2.

[0057] Comparative Example 1 The difference between this comparative example and Example 1 is that: Step 1, preparation of D prepolymer: after adding octaphenyl ring body to the polymerization kettle, the feeding needs to be stopped, and after the oil temperature rises to 85°C, vacuum drying is carried out for 25 minutes, and then under the protection of dry nitrogen, octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid are added in sequence; stirring is turned on, and after the internal temperature reaches 75°C, a ring-opening polymerization reaction is carried out for 0.4h, and a sample is taken to test the viscosity. When the viscosity reaches 15mPa·s, the solid acid catalyst is filtered out and removed, and the short-path distiller is preheated to 140°C, and the internal pressure is 105Pa, and the polymer is slowly passed through the short-path distiller to remove unreacted monomers and other low molecular weight compounds, so as to obtain the preparation of D prepolymer; Step 2, preparation of T prepolymer: add phenyltrimethoxysilane, methyltrimethoxysilane and toluene to the silicon prepolymer kettle in sequence; start stirring; add deionized water and hydrochloric acid to the high-level tank; close the extraction valve, open the vent valve, adjust the valve to the reflux state, turn on the condenser cooling water; turn on the jacket cooling water, slowly add acid water to the reaction system through the flow meter, control the dropping speed, and finish the dropping in 0.4h, and control the internal temperature at 35℃; after the acid water is added, steam is used for heating and the initial temperature is set at 45℃ to avoid material rushing; the material digital display temperature rises When the temperature reaches 50℃, the steam opening is turned down, and the digital display temperature of the material rises to 65℃ and starts to reflux, which is maintained for 1.8h. The valve is adjusted to the water separation state, methanol and water are evaporated, and the timing is started when the system is transparent. The reaction is continued for 0.3h, and the heating is stopped. The jacket is cooled with cooling water. After the reaction is completed, the temperature is lowered to 42℃, and the cooling water is turned off. Na2CO3 is added to neutralize the catalyst, and the product is dried with an activated 4A molecular sieve in a sealed container at 18℃ for 10h. The product is filtered with a filter cloth under the protection of dry nitrogen until there is no visible suspended impurities in the transparent solution, and a T prepolymer is obtained; Step 3, add the D-type prepolymer, T-type prepolymer and borane catalyst to a nitrogen-protected and fully dried copolymerization kettle, react at 20°C for 45 hours, gradually heat to 110°C, keep warm for 0.5 hours, and obtain a low molecular weight intermediate polymer by block polymerization; after cooling to 45°C, add xylene for dilution, add a condensation catalyst, heat to reflux temperature, reflux with water, and carry out condensation reaction, control the internal temperature at 120°C, condense for 5 hours, and cool to obtain methylphenyl silicone resin after the viscosity reaches 140mPa·s.

[0058] Wherein, in the step 1, before adding octaphenylcyclotetrasiloxane, check and make sure that the bottom valve of the polymerization kettle is in a closed state, the vent valve is in an open state, turn on the heating power of the polymerization kettle, and set the oil temperature to 130°C.

[0059] Wherein, in the step 1, octamethylcyclotetrasiloxane is added from the dehydration kettle to the polymerization kettle using a metering pump; the stirring speed is 140r / min.

[0060] Wherein, in the step 2, before adding phenyltrimethoxysilane, check and make sure that the bottom valve of the silicon prepolymer kettle is closed, close the vent valve, and open the extraction valve; the stirring speed is 190r / min; the condenser uses a disc condenser, the cooling water temperature is 20°C, and the maximum flow rate is 9m 3 / h; the steam temperature is 130℃, the pressure is 2.0Mpa, and the flow rate is 0.8t / h; the heating rate is 0.4℃ / min; the purity of Na2CO3 is 98% and the particle size is 0.07mm.

[0061] Among them, in the step three, the heating rate is 0.6°C / min when gradually heating up; xylene is added through the high-level tank for dilution; the temperature is cooled to 32°C, and the cooling rate is 2.8°C / min.

[0062] Comparative Example 2 The difference between this comparative example and Example 1 is that, in step 1, the mass ratio of octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid is 100:35:7:0.8.

[0063] Wherein, in the step 2, the mass ratio of phenyltrimethoxysilane, methyltrimethoxysilane, toluene, deionized water and hydrochloric acid is 100:240:290:190:0.04.

[0064] Wherein, in the step three, the mass ratio of D-type prepolymer, T-type prepolymer, borane catalyst, xylene and condensation catalyst is 100:75:0.08:55:0.08.

[0065] Comparative Example 3 The difference between this comparative example and Example 3 is that: Step 1, preparation of D prepolymer: after adding octaphenyl ring body to the polymerization kettle, the feeding needs to be stopped, and after the oil temperature rises to 130°C, vacuum drying is carried out for 65 minutes, and then under the protection of dry nitrogen, octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid are added in sequence; stirring is turned on, and after the internal temperature reaches 110°C, a ring-opening polymerization reaction is carried out for 2.2 hours, and a sample is taken to test the viscosity. When the viscosity reaches 55mPa·s, the solid acid catalyst is filtered out and removed, and the short-path distiller is preheated to 190°C, and the internal pressure is 95Pa, and the polymer is slowly passed through the short-path distiller to remove unreacted monomers and other low molecular weight compounds, to obtain the preparation of D prepolymer; Step 2, preparation of T prepolymer: add phenyltrimethoxysilane, methyltrimethoxysilane and toluene to the silicon prepolymer kettle in turn; start stirring; add deionized water and hydrochloric acid to the high-level tank; close the extraction valve, open the vent valve, adjust the valve to the reflux state, turn on the condenser cooling water; turn on the jacket cooling water, slowly add acid water to the reaction system through the flow meter, control the dropping speed, and finish dropping in 0.6 hours, and control the internal temperature at 55°C; after the acid water is added, steam is used for heating and the initial temperature is set at 57°C to avoid material rushing; the material digital display temperature When the temperature rises to 65°C, the steam opening is turned down, and the digital display temperature of the material rises to 70°C and starts to reflux, which is maintained for 2.2 hours. The valve is adjusted to the water separation state, methanol and water are evaporated, and the timing is started when the system is transparent. The reaction is continued for 1 hour, and the heating is stopped. The jacket is cooled with cooling water. After the reaction is completed, the temperature is lowered to 42°C, and the cooling water is turned off. Na2CO3 is added to neutralize the catalyst, and the product is dried with an activated 4A molecular sieve in a closed container at 42°C for 40 hours. The product is filtered with a filter cloth under the protection of dry nitrogen until there is no visible suspended impurities in the transparent solution, and a T prepolymer is obtained; Step 3, add the D-type prepolymer, T-type prepolymer and borane catalyst to a nitrogen-protected and fully dried copolymerization kettle, react at 42°C for 100h, gradually heat to 115°C, keep warm for 1.5h, and obtain a low molecular weight intermediate polymer by block polymerization; when the temperature is cooled to 52°C, add xylene for dilution, add a condensation catalyst, heat to reflux temperature, reflux with water, and carry out condensation reaction, control the internal temperature at 140°C, condense for 18h, and cool to obtain methylphenyl silicone resin after the viscosity reaches 145mPa·s.

[0066] Wherein, in the step 1, before adding octaphenylcyclotetrasiloxane, check and make sure that the bottom valve of the polymerization kettle is in a closed state, the vent valve is in an open state, turn on the heating power of the polymerization kettle, and set the oil temperature to 180°C.

[0067] Wherein, in the step 1, octamethylcyclotetrasiloxane is added from the dehydration kettle to the polymerization kettle using a metering pump; the stirring speed is 320r / min.

[0068] Wherein, in the step 2, before adding phenyltrimethoxysilane, check and make sure that the bottom valve of the silicon prepolymer kettle is closed, close the vent valve, and open the extraction valve; the stirring speed is 620r / min; the condenser uses a disc condenser, the cooling water temperature is 27°C, and the maximum flow rate is 11m 3 / h; the steam temperature is 140℃, the pressure is 2.3Mpa, and the flow rate is 1.2t / h; the heating rate is 1.2℃ / min; the purity of Na2CO3 is 99% and the particle size is 0.2mm.

[0069] Wherein, in the step three, the heating rate is 1°C / min when gradually heating up; xylene is added through the high-level tank for dilution; the temperature is cooled down to 42°C, and the cooling rate is 3.2°C / min.

[0070] Comparative Example 4 The difference between this comparative example and Example 3 is that, in step 1, the mass ratio of octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid is 100:50:18:7.

[0071] Wherein, in the step 2, the mass ratio of phenyltrimethoxysilane, methyltrimethoxysilane, toluene, deionized water and hydrochloric acid is 100:310:4100:260:0.6.

[0072] Wherein, in the step three, the mass ratio of D-type prepolymer, T-type prepolymer, borane catalyst, xylene and condensation catalyst is 100:170:0.6:310:0.6.

[0073] The heat resistance of the high heat-resistant silicone resin obtained in Example 1 to Example 8 and Comparative Example 1 to Comparative Example 4 after complete curing is shown in the following table. Heat resistance (under air atmosphere, 10% weight loss temperature is not less than 550°C, 1000°C weight retention rate is not less than 52%) is tested using a thermogravimetric analyzer (TGA) with reference to GB / T 33047.1-2016, heating rate 10°C / min, air atmosphere. The typical spectrum of TGA of the high heat-resistant silicone resin obtained in Example 6 is as follows Figure 2 shown.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a high heat-resistant silicone resin, characterized in that: The following steps are involved: Step 1, preparation of D prepolymer: after adding octaphenyl ring body to the polymerization kettle, the feeding needs to be stopped, and after the oil temperature rises to 90-120°C, vacuum drying is carried out for 30-60min, and then octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid are added in sequence under the protection of dry nitrogen; stirring is started, and after the internal temperature reaches 80-100°C, a ring-opening polymerization reaction is carried out for 0.5-2h, and a sample is taken to test the viscosity. When the viscosity reaches 20-50mPa·s, the solid acid catalyst is filtered out and the short-path distiller is preheated to 150-180°C, and the internal pressure is not higher than 100Pa, and the polymer is slowly passed through the short-path distiller to remove unreacted monomers and other low molecular weight compounds, so as to obtain the preparation of D prepolymer; Step 2, preparation of T prepolymer: add phenyltrimethoxysilane, methyltrimethoxysilane and toluene to the silicon prepolymer kettle in sequence; start stirring; add deionized water and hydrochloric acid to the high-level tank; close the extraction valve, open the vent valve, adjust the valve to the reflux state, turn on the condenser cooling water; turn on the jacket cooling water, slowly add acid water to the reaction system through the flow meter, control the dropping speed, and finish the dropping in 0.5h. The internal temperature is controlled at 40-50℃; after the acid water is added, steam is used for heating and the initial temperature is set at 50-55℃ to avoid material rushing; the material digital display temperature rises to 55-6 At 0℃, turn down the steam opening, the digital display temperature of the material rises to 67-69℃ and starts to reflux, keep it for 2h, adjust the valve to the water separation state, evaporate methanol and water, start timing when the system is transparent, continue the reaction for 0.3-0.8h, stop heating, pass cooling water through the jacket to cool down, cool down to below 40℃ after the reaction, turn off the cooling water, add Na2CO3 to neutralize the catalyst, dry it with activated 4A molecular sieve in a closed container at 20-40℃ for 12-36h, filter it with filter cloth under the protection of dry nitrogen until there is no visible suspended impurities in the transparent solution, and obtain T prepolymer; Step 3, add the D-type prepolymer, T-type prepolymer and borane catalyst to a nitrogen-protected and fully dried copolymerization kettle, react at 25-40°C for 48-96h, gradually heat to 110°C, keep warm for 0.5-1h, and obtain a low molecular weight intermediate polymer by block polymerization; after cooling to below 50°C, add xylene for dilution, add a condensation catalyst, heat to reflux temperature, reflux with water, and carry out polycondensation reaction, control the internal temperature at 125-135°C, polycondense for 6-16h, and cool to obtain methylphenyl silicone resin after the viscosity reaches 140mPa·s.

2. The method for preparing a highly heat-resistant silicone resin according to claim 1, characterized in that: In the step 1, before adding octaphenylcyclotetrasiloxane, check and make sure that the bottom valve of the polymerization kettle is in a closed state, the vent valve is in an open state, turn on the heating power of the polymerization kettle, and set the oil temperature to 140-170°C.

3. The method for preparing a highly heat-resistant silicone resin according to claim 1, characterized in that: In the step 1, the mass ratio of octaphenylcyclotetrasiloxane, octamethylcyclotetrasiloxane, tetramethyldisiloxane and solid acid is 100:40-48:8-16:1-6.

4. The method for preparing a highly heat-resistant silicone resin according to claim 1, characterized in that: In the step 1, the solid acid can be any one of cation exchange resin, BF3 / Al2O3, ZSM-5 molecular sieve, Y molecular sieve, H3PW12O40, SO42- / ZrO2, and WO3 / ZrO2.

5. The method for preparing a highly heat-resistant silicone resin according to claim 1, characterized in that: In the step 1, octamethylcyclotetrasiloxane is added from the dehydration kettle to the polymerization kettle using a metering pump; the stirring speed is 150-300 r / min.

6. The method for preparing a highly heat-resistant silicone resin according to claim 1, characterized in that: In the step 2, before adding phenyltrimethoxysilane, check and make sure that the bottom valve of the silicon prepolymer kettle is closed, close the vent valve, and open the extraction valve; the stirring speed is 200-600r / min; the condenser uses a disc condenser, the cooling water temperature is not higher than 25°C, and the maximum flow rate is not less than 10 m 3 / h; the temperature of steam is not less than 135℃, the pressure is not less than 2.13Mpa, and the flow rate is not less than 1t / h; the heating rate is 0.5-1℃ / min; the purity of Na2CO3 is not less than 99%, and the particle size is between 0.08mm-0.15mm.

7. The method for preparing a highly heat-resistant silicone resin according to claim 1, characterized in that: In the step 2, the mass ratio of phenyltrimethoxysilane, methyltrimethoxysilane, toluene, deionized water and hydrochloric acid is 100: 250-300: 300-400: 200-250: 0.05-0.

5.

8. The method for preparing a highly heat-resistant silicone resin according to claim 1, characterized in that: In the step 3, the mass ratio of the D-type prepolymer, the T-type prepolymer, the borane catalyst, the xylene, and the condensation catalyst is 100:80-160:0.1-0.5:60-300:0.1-0.

5.

9. The method for preparing a highly heat-resistant silicone resin according to claim 1, characterized in that: The condensation catalyst is a dehydrogenation coupling catalyst, and the dehydrogenation coupling catalyst is any one of chloroplatinic acid, platinum nanoparticles, metal hydride, Custer platinum catalyst, BF3, and B(C6F5)3.

10. The method for preparing a highly heat-resistant silicone resin according to claim 1, characterized in that: In the step three, the heating rate is 0.7-0.9°C / min when gradually heating up; xylene is added through a high-level tank for dilution; the temperature is cooled down to below 40°C, and the cooling rate of the cooling down is not less than 3°C / min.

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