阅读说明：本技术 一种耐高温含硼硅树脂的制备方法 (Preparation method of high-temperature-resistant borosilicate-containing resin ) 是由 殷琪峰 李明伟 曾岗 孙宇雷 张一凡 李文浩 钟业盛 史丽萍 赫晓东 何飞 于 2021-09-30 设计创作，主要内容包括：一种耐高温含硼硅树脂的制备方法,它涉及树脂领域,本发明要解决改性硅树脂,尤其是含硼硅树脂的制备方法复杂,耐热性不理想的问题。本发明将硼酸与甲基三甲氧基硅烷混合,进行二个阶段反应,然后将反应产物进行烘干,即得。本发明采用溶胶-凝胶法制备一种具有高耐热能力的硅树脂,制备过程简单,可复现性良好,且通过形成在硅树脂中的Si-O-B键提升其耐温能力。本发明的方法高温热解时无晶态物质析出,耐热性能良好,适合中试放大生产。本发明应用于航空,航天和民用领域。(The invention discloses a preparation method of high-temperature-resistant borosilicate-containing resin, relates to the field of resin, and aims to solve the problems of complex preparation method and unsatisfactory heat resistance of modified silicon resin, particularly boron-containing silicon resin. The invention mixes boric acid and methyltrimethoxysilane, carries out two-stage reaction, and then dries the reaction product, thus obtaining the product. The invention adopts the sol-gel method to prepare the silicone resin with high heat resistance, the preparation process is simple, the reproducibility is good, and the temperature resistance of the silicone resin is improved through Si-O-B bonds formed in the silicone resin. The method of the invention has the advantages of no crystalline substance precipitation during high-temperature pyrolysis, good heat resistance and suitability for pilot scale production. The invention is applied to the fields of aviation, aerospace and civil use.)

1. The preparation method of the high-temperature-resistant borosilicate-containing resin is characterized by comprising the following steps of:

(1) mixing boric acid and methyltrimethoxysilane according to the molar ratio of Si and B of 1: mixing at a ratio of 0.1-1.0, and transferring to a reactor after mixing;

(2) the reaction is heated by water bath, and is carried out for 2 to 6 hours by adopting a condensation reflux mode under the conditions that the stirring speed is 200 to 800r/min and the reaction temperature is 50 to 70 ℃, thus finishing the first-stage reaction;

(3) continuously reacting the reactant which finishes the first-stage reaction for 0.5 to 2 hours at the temperature of between 80 and 90 ℃ to finish the second-stage reaction;

(4) transferring the reaction product in the step (3) into a container, and then drying the reactant at the temperature of 80-100 ℃ for 24-48 h; thus completing the preparation of the high-temperature-resistant boron-containing silicone resin.

2. The method for preparing high temperature-resistant borosilicate-containing resin according to claim 1, wherein in step (1), the ratio of boric acid to methyltrimethoxysilane is 1: mixing at a ratio of 0.2-0.8.

3. The method for preparing a high temperature-resistant borosilicate-containing resin according to claim 1 or 2, wherein in the step (1), the ratio of boric acid to methyltrimethoxysilane is 1: mixing at a ratio of 0.3-0.6.

4. The method for preparing high temperature-resistant borosilicate-containing resin according to claim 3, wherein the molar ratio of boric acid to methyltrimethoxysilane in Si and B in step (1) is 1: mixing at a ratio of 0.4-0.5.

5. The process according to claim 1, wherein the water in the water bath heated in the water bath in the step (2) has a level higher than the level of the reaction solution in the reactor.

6. The preparation method of the high temperature resistant borosilicate-containing resin according to claim 1, wherein the reaction in step (2) is carried out by heating in water bath, and the reaction is carried out for 2 to 4 hours in a condensation reflux manner under the conditions of a stirring speed of 400 to 600r/min and a reaction temperature of 50 to 60 ℃, thereby completing the reaction in the first stage.

7. The preparation method of the high temperature resistant borosilicate-containing resin according to claim 1 or 6, wherein the reaction in step (2) is carried out by heating in water bath, and the reaction is carried out for 3h to 4h in a condensation reflux manner under the conditions of a stirring speed of 500r/min to 600r/min and a reaction temperature of 50 ℃ to 60 ℃ to complete the reaction in the first stage.

8. The method for preparing high temperature-resistant borosilicate-containing resin according to claim 1, wherein in the step (3), the reactants are reacted at 80-90 ℃ for 1-2 h to complete the second stage reaction.

9. The method for preparing the high-temperature-resistant borosilicate-containing resin according to claim 1, wherein in the step (4), the reaction product obtained in the step (3) is transferred into a container, and then the reaction product is dried at 80-100 ℃ for 36-48 h.

10. The method for preparing high temperature-resistant borosilicate-containing resin according to claim 1, wherein in step (3), if a film-like solid substance is generated during the reaction, the film-like solid substance is removed.

Technical Field

The invention relates to the field of resin, in particular to a preparation method of high-temperature-resistant borosilicate-containing resin.

Background

The silicone resin is a high polymer having a main chain formed by a Si — O — Si bond, R1R2SiO- (R1, R2 is an alkyl group or an aromatic group) as a structural unit, and at least one organic group is bonded to a silicon atom, and has excellent heat resistance, cold resistance, electrical properties, weather resistance, and the like, and thus has attracted attention of researchers. With the increasing requirements on the performance of silicone in the fields of aviation, aerospace and civil use, boron-containing silicone resin has excellent heat resistance, and can become excellent high-temperature-resistant adhesives, high-temperature-resistant coatings, high-temperature-resistant flame retardants and the like, so that the boron-containing silicone resin is favored by many scholars. Compared with other methods for modifying the silicone resin, the method for improving the heat resistance of the silicone resin by doping the B atoms is a hot spot of research, but the preparation process is complicated. For example, in the document of CN201210461157.5, although the boron-containing silicone resin is prepared by the sol-gel method by hunberg et al, the university of guangdong industry, the heat resistance is more desirable, the preparation reactant is more, the process is more complicated, and the mass loss occurs about 5% at about 200 ℃. For example, Wangdan et al, university of Guangdong industry in 2015, prepares boron-containing silicon resin containing phenyl by a sol-gel method according to the condition that R/Si is 1.3 and the water consumption is 60 percent, improves the heat resistance, does not have violent decomposition at low temperature, and has less than 60 percent of the mass of pyrolysis products at 800 ℃. For example, in the document of patent No. cn201610362812.x, von shihai et al, institute of aerospace materials and technology, prepared boron-containing silicone resin by "one-pot ammonolysis method" and the prepared boron-containing silicone resin has improved heat resistance, and the residual rate of pyrolysis product is about 75% at 800 ℃. By adopting a sol-gel method, the Wangcan et al of the university of Harbin industry in 2017 prepares the boron-containing silicon resin, the monomer raw materials of the boron-containing silicon resin are methyl triethoxysilane and boric acid, the prepared boron-containing silicon resin has about 10 percent of mass loss at 120 ℃, and the mass residual mass of the boron-containing silicon resin is 80.5 percent at the high temperature of 800 ℃. The reaction process needs nitrogen, the conditions are harsh, the reactants and the reaction products are more, and the process is complex. At present, few reports exist that boron-containing silicone resin with good heat resistance and simple preparation process can be prepared.

Disclosure of Invention

The invention aims to solve the problems of complex preparation method and unsatisfactory heat resistance of modified silicon resin, particularly boron-containing silicon resin, and provides a preparation method of high-temperature-resistant boron-containing silicon resin. The invention adopts the sol-gel method to prepare the silicone resin with high heat resistance, the preparation process is simple, the reproducibility is good, and the temperature resistance of the silicone resin is improved through Si-O-B bonds formed in the silicone resin.

The invention relates to a preparation method of high-temperature-resistant borosilicate-containing resin, which is carried out according to the following steps:

(1) mixing boric acid and methyltrimethoxysilane according to the molar ratio of Si and B of 1: mixing at a ratio of 0.1-1.0, and transferring to a reactor after mixing;

(2) the reaction is heated by water bath, and is carried out for 2 to 6 hours by adopting a condensation reflux mode under the conditions that the stirring speed is 200 to 800r/min and the reaction temperature is 50 to 70 ℃, thus finishing the first-stage reaction;

(3) continuously reacting the reactant which finishes the first-stage reaction for 0.5 to 2 hours at the temperature of between 80 and 90 ℃ to finish the second-stage reaction;

(4) transferring the reaction product in the step (3) into a container, and then drying the reactant at the temperature of 80-100 ℃ for 24-48 h; thus completing the preparation of the high-temperature-resistant boron-containing silicone resin.

Further, in the step (1), the molar ratio of boric acid to methyltrimethoxysilane is 1: mixing at a ratio of 0.2-0.8.

Further, in the step (1), the molar ratio of boric acid to methyltrimethoxysilane is 1: mixing at a ratio of 0.3-0.6.

Further, in the step (1), the molar ratio of boric acid to methyltrimethoxysilane is 1: mixing at a ratio of 0.4-0.5.

Further, the liquid level of the water in the water bath in the step (2) is higher than the liquid level of the reaction liquid in the reactor.

Further, the reaction in the step (2) adopts water bath heating, and the reaction is carried out for 2 to 4 hours in a condensation reflux mode under the conditions that the stirring speed is 400 to 600r/min and the reaction temperature is 50 to 60 ℃, so as to complete the reaction of the first stage.

Further, the reaction in the step (2) adopts water bath heating, and the reaction is carried out for 3 to 4 hours in a condensation reflux mode under the conditions that the stirring speed is 500 to 600r/min and the reaction temperature is 50 to 60 ℃, so as to complete the reaction of the first stage.

Further, in the step (3), the reactants react for 1 to 2 hours at the temperature of between 80 and 90 ℃ to finish the second stage reaction.

Further, in the step (4), the reaction product in the step (3) is transferred into a container, and then the reactant is dried for 36-48 h at the temperature of 80-100 ℃.

Further, in the step (3), if the solid film-like substances appear in the reaction process, taking out the solid substances for removal.

The invention has the following beneficial effects:

the high-temperature-resistant boron-containing silicon resin provided by the invention has the advantages that the used raw materials are chemically pure, the raw materials are low in toxicity, simple and easily available, the raw materials are subjected to hydrolysis-polycondensation reaction in a reactor, the hydroxyl on boric acid and the hydroxyl and methoxyl on silanol are subjected to condensation and substitution reaction, deionized water is not required to be added, so that B atoms are keyed into the main chain of the silicon resin, the boron-containing silicon resin is finally generated, and no toxic substance is generated in the reaction process. The method is simple, easy to operate and high in reproducibility, and the prepared boron-containing silicone resin has high heat resistance, basically has no decomposition (see figures 4 and 5) at 250 ℃, and has more than 82% of residual weight (see figures 4 and 5) at 800 DEG C

The mechanism in the hydrolysis-polycondensation process of the present invention is shown in the following formulas (1) to (5):

＝B-OH+≡Si-OR→≡Si-OH+＝B-OR (1)

＝B-OH+≡Si-OH→≡Si-O-B＝+H₂O (2)

＝B-OH+≡Si-OR→≡Si-O-B＝+ROH (3)

≡Si-OR+H₂O→≡Si-OH+＝ROH (4)

≡Si-OH+≡Si-OH→≡Si-O-Si≡+H₂O (5)

in the actual hydrolysis-polycondensation, the reaction (5) is the most dominant, and Si-O-B is mainly provided by the reaction (2), and it is known from the formula (2) and the prior art that the addition of deionized water should be controlled during the reaction to increase the formation rate of Si-O-B bonds and reduce the decomposition thereof, so that the present invention does not add water during the reaction. In addition, the invention adopts the methyl siloxysilane monomer, the C element on the monomer is less, and the Si-O reaction unit is more, so that the Si-O-B bond proportion in the reaction process is improved by phase change, and the heat resistance of the boron-containing silicon resin is improved. No crystalline substance is separated out during high-temperature pyrolysis, the heat resistance is good, and the method is suitable for pilot scale production.

Drawings

FIG. 1 shows FT-IR spectrum of boron-containing silicone sol prepared by example 1;

FIG. 2 shows FT-IR spectrum of boron-containing silicone gel prepared by example 1;

FIG. 3 shows the XRD pattern of the boron-containing silicone gel prepared in example 1;

FIG. 4 shows TG/DSC plots for boron-containing silicone prepared from example 1;

FIG. 5 shows TG/DTG profile of boron-containing silicone resin prepared by example 1;

FIG. 6 shows FT-IR plots of boron-containing silicone resin prepared in example 1 after pyrolysis at different temperatures;

FIG. 7 shows XRD profiles of boron-containing silicone resin prepared from example 1 after pyrolysis at different temperatures.

Detailed Description

For the purpose of promoting a clear understanding of the objects, aspects and advantages of the embodiments of the invention, reference will now be made in detail to the embodiments of the present disclosure, and it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the disclosure.

The exemplary embodiments of the present invention and the description thereof are provided to explain the present invention and not to limit the present invention.

The effective results of the present invention are verified by the following examples:

example 1

The preparation method of the boron-containing silicone resin of the embodiment is as follows:

(1) 6.18g of boric acid was dispersed in 27.24g of methyltrimethoxysilane and subsequently transferred to a reactor for reaction;

(2) the reactor is placed in a water bath heating environment, the heating temperature is 70 ℃, the reaction time is 4 hours, condensation reflux and magnetic stirring are carried out in the reaction process, and the stirring speed is 400 r/min;

(3) continuously reacting the reactants in the reactor in the previous step at 90 ℃ for 0.5h, and keeping the rest reaction conditions unchanged;

(4) transferring the glue solution into a container after the reaction is finished, and then drying the glue solution for 48 hours at the temperature of 70 ℃ without sealing the container;

FIG. 1 shows that the B-O-Si bond is contained in the hydrolyzed-polycondensed sol solution, and the boron-containing silicone sol is successfully prepared;

FIG. 2 illustrates that the gel after the glue solution is cured contains B-O-Si bonds, and boron-containing silicone resin gel is successfully prepared;

FIG. 3 illustrates the absence of excess H in the gel₃BO₃The element B fully enters the silicon resin;

FIGS. 4 and 5 illustrate the heat resistance and the change in mass and energy after heating of a borosilicate-containing resin;

FIG. 6 illustrates that the borosilicate resin has no significant change in molecular structure when pyrolyzed at high temperature, and shows that the B element is present in the main chain, not in small molecule species;

FIG. 7 illustrates that when the borosilicate resin is pyrolyzed at high temperature, an amorphous substance is precipitated, demonstrating good thermal stability;

the raw materials used in the high temperature resistant boron-containing silicone resin of the embodiment are all chemically pure, and the raw materials are subjected to hydrolysis-polycondensation reaction in a reactor, and the hydroxyl groups on boric acid and the hydroxyl groups and methoxy groups on silanol are subjected to condensation and substitution reaction, so that B atoms are bonded into the main chain of the silicone resin, and finally the boron-containing silicone resin is generated. The method is simple, easy to operate and strong in reproducibility, and the prepared boron-containing silicone resin is strong in heat resistance, basically free of decomposition at the temperature of 250 ℃, and has more than 82% of residual weight at the temperature of 800 ℃.