Preparation method of organic silicon modified boron phenolic resin composite material

Abstract

The invention discloses a preparation method of an organic silicon modified boron phenolic resin composite material. The method comprises the following steps: reacting boron phenolic resin with isocyanate propyl alkoxy silane in an organic solvent at 75-85 DEG C in the presence of organic tin dilaurate to prepare organic silicon modified boron phenolic resin; dissolving organic silicon modified boron phenolic resin and hydroxyl-terminated polymethylsiloxane in an organic solvent at room temperature, uniformly mixing, heating to volatilize the organic solvent, adding organic tin dilaurate after the organic solvent is volatilized, uniformly mixing, standing, reacting and defoaming; and then curing at room temperature to obtain the organic silicon modified boron phenolic resin composite material. By means of excellent flexibility and heat resistance of organic silicon and excellent rigidity and ablation resistance of phenolic resin, the prepared material is resistant to high temperature, can be used as an advanced composite material matrix, an organic thermal protection material matrix and the like, and has wide application prospects in thermal protection materials of buildings and cables and thermal protection materials of hypersonic weaponry.

Description

Technical Field

[0001] The invention belongs to the field of polymer-based composite materials, and particularly relates to a method for preparing a novel organosilicon-modified boron phenolic resin composite material. Background Art

[0002] When missiles, spacecraft and hypersonic vehicles pass through the atmosphere, the surface temperature increases due to aerodynamic heating. The use of thermal protection materials can be used as a protective and heat-insulating layer to protect and reduce the erosion of the aircraft surface by the generated heat. In addition, frequent fires have caused significant losses to people's personal safety and property. The key to reducing fire losses is to slow down the spread of flames while ensuring the smooth flow of power, communication lines and escape routes. At present, there is a great demand for polymer-based heat-resistant protective materials.

[0003] Silicone-based protective materials have become the new favorite of organic heat-resistant materials due to their advantages of convenient processing, high heat resistance and excellent protective performance. Introducing phenolic resin or boron phenolic resin with a higher carbonization rate into silicone resin can effectively improve its heat resistance. However, boron phenolic resin and silicone have poor compatibility, making it difficult to successfully make composite heat-resistant materials. Summary of the invention

[0004] In view of the defects or shortcomings of the prior art, the present invention provides a method for preparing an organosilicon-modified boron phenolic resin composite material.

[0005] To this end, the method for preparing the organosilicon-modified boron phenolic resin composite material provided by the present invention comprises:

[0006] (1) boron phenolic resin and isocyanate propyl alkoxy silane react in a first organic solvent at 75-85° C. in the presence of organotin dilaurate to prepare organosilicon-modified boron phenolic resin;

[0007] (2) at room temperature, the organosilicon-modified boron phenolic resin and the hydroxyl-terminated polymethylsiloxane are dissolved in a second organic solvent, mixed and heated to volatilize the second organic solvent, and after the second organic solvent is volatilized, dilaurate organotin is added, mixed and allowed to stand for reaction and degassing; and then cured at room temperature to obtain an organosilicon-modified boron phenolic resin composite material. In a specific scheme, the heating temperature in step (2) is set to achieve volatilization of the second organic solvent, specifically determined according to the volatilization temperature of the second organic solvent or slightly lower than the volatilization temperature of the second organic solvent, to accelerate its volatilization.

[0008] Alternatively, the organotin dilaurate is selected from dibutyltin dilaurate.

[0009] Alternatively, the isocyanate propyl alkoxy silane is selected from isocyanate propyl triethoxy silane.

[0010] An optional solution is that the mass ratio of the boron phenolic resin to the isocyanate propyl alkoxy silane is (50-20): (60-20).

[0011] An optional solution is that the first solvent is selected from one or a mixture of two or more of ethanol, acetone or ethyl acetate, and the second solvent is selected from one or a mixture of two or more of ethanol, acetone or ethyl acetate.

[0012] An optional solution is that in step (1), the mass ratio of organotin dilaurate to isocyanatepropylalkoxysilane is 1:(50-1000).

[0013] An optional solution is that in step (2), the mass ratio of organotin dilaurate to hydroxyl-terminated polymethylsiloxane is 1:(50-500).

[0014] The present invention utilizes a method for preparing a silicone-grafted phenolic resin, selects various phenolic resins with alkoxysilane as a matrix, and directly obtains a hybrid phenolic resin through a one-step reaction. The hybrid phenolic resin can be directly used as a resin matrix of a composite material of a protective material and reacts with silicone, thereby broadening the application field of phenolic resin products.

[0015] In addition, the organosilicon grafted phenolic resin and the composite material prepared by the present invention have excellent heat resistance and have broad application prospects in heat-insulating materials for buildings and cables and heat-protective materials for hypersonic weapons and equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Preparation roadmap for the invented organosilicon-grafted phenolic resin and its composite materials

[0017] Figure 2 This is the infrared spectrum of phenolic resin and modified phenolic resin.

[0018] Figure 3 The morphology diagrams of the samples of Example 1 and Comparative Example 1 are shown in FIG.

[0019] Figure 4 Thermogravimetric diagrams of samples of Example 1 and Comparative Example 1.

[0020] Figure 5 The morphology pictures of the samples of comparative examples 2 and 3 are shown. DETAILED DESCRIPTION

[0021] Unless otherwise specified, the scientific and technical terms used herein are understood according to the knowledge of ordinary technicians in the relevant fields.

[0022] The present invention changes the molecular chain segment structure of the phenolic resin so that the phenolic resin and the organic silicon matrix are chemically connected, so that the effects of each component can be well exerted, and the prepared polymer-based protective material has better heat resistance. Figure 1 As shown, the organosilicon-modified boron phenolic resin is prepared by reacting the phenolic hydroxyl group of the boron phenolic resin with an isocyanate propyl alkoxy silane such as isocyanate propyl triethoxy silane. The skeleton of the organosilicon-modified boron phenolic resin is a phenolic resin, and isocyanate propyl trimethoxy silane is grafted onto the phenolic resin, so that the surface of the material has an ethoxy group that is easily hydrolyzed, and the grafted ethoxy active group can directly participate in the cross-linking reaction of polysiloxane. When the organosilicon-modified phenolic resin of the present invention is used to prepare an organosilicon composite material, not only the cross-linking density of polysiloxane is increased, but also the large volume structure of the organosilicon-modified phenolic resin can well control the movement of polysiloxane chain segments.

[0023] The technical solution of the present invention is further described below, but it is not limited thereto. Any equivalent replacement of the specific substances, preparation methods, formulas, processing temperatures, durations, etc. involved in the technical solution of the present invention, which does not depart from the spirit and scope of the technical solution of the present invention, should be included in the protection scope of the present invention. Except for the organosilicon-modified phenolic resin, the other raw materials used in the following examples are all commercially available products.

[0024] Embodiment 1:

[0025] (1) Preparation of organosilicon-modified boron phenolic resin:

[0026] Weigh 30.67g of boron phenolic resin and dissolve it in ethanol. After it is fully dissolved, add three drops of dibutyltin dilaurate (about 0.1g). Then place it in an oil bath at about 80°C, and add 21.83g of isocyanate propyltriethoxysilane to the mixed solution (drop by drop, and the addition is completed within 30 minutes). After the addition is completed, react at 80°C for 5 hours.

[0027] After the reaction is completed, the mixture is cooled to room temperature, and the solvent and by-products are removed by a rotary evaporator. The rotary temperature is first set to 70° C. and then raised to 100° C. to finally obtain an organosilicon-modified boron phenolic resin.

[0028] pass Figure 2 The infrared analysis shows that the obtained organosilicon-modified boron phenolic resin retains the skeleton of the phenolic resin, 1422 cm -1 -CH- deformation vibration in the methylene bridge, 1224cm -1 The antisymmetric stretching vibration of CO on the phenol ring at 752 cm -1 The out-of-plane bending vibration of the CH on the benzene ring remains unchanged, while the isocyanate propyl triethoxysilane is chemically bonded or grafted to the phenolic resin, and the silane can be seen at 2276 cm-1 The isocyanate group at 1693 cm-1 disappears in the modified phenolic resin and is generated at 1693 cm-1. -1 The carbonyl group, such as Figure 2 As shown, it is shown that the organosilicon-modified boron phenolic resin is successfully obtained.

[0029] (2) Preparation of organosilicon-modified boron phenolic resin composite materials:

[0030] At room temperature, 7.9 g of organosilicon-modified boron phenolic resin was dissolved in ethanol, and then 50 g of hydroxyl-terminated polymethylsiloxane was added to the ethanol solution of organosilicon-modified phenolic resin. After mixing evenly, the mixture was placed in a vacuum oven at about 40°C to remove the solvent ethanol. After the solvent was completely volatilized, the mixture was taken out and dried to room temperature.

[0031] Then, 3 drops of dibutyltin dilaurate (about 0.1 g) were added, mixed and allowed to stand for reaction and degassing; finally, it was introduced into a polytetrafluoroethylene mold and cured at room temperature for 5 days to obtain the organosilicon-modified boron phenolic resin composite material of this embodiment. The macroscopic morphology of the composite material is as follows Figure 3 As shown in Figure B, the material is uniform bright yellow and has no phase separation. Thermogravimetric testing of its thermal stability ( Figure 4 ), the residual rate after complete decomposition is 28% (this value is the vertical axis value corresponding to 800°C).

[0032] Comparative Example 1:

[0033] The difference between this comparative example and Example 1 is that the organosilicon-modified phenolic resin is replaced by an equal amount of boron phenolic resin. The macroscopic morphology of the prepared composite material is as follows: Figure 3 As shown in Figure A, the material is earthy yellow and has phase separation. The thermal stability is tested by thermogravimetric method ( Figure 4 ), the residual rate after complete decomposition is 16% (this value is the vertical axis value corresponding to 800℃).

[0034] By comparing the thermogravimetric test results of Example 1 and Comparative Example 1, it can be seen that the material prepared in Example 1 not only has no phase separation, but also has better heat resistance and higher residual rate.

[0035] Comparative Example 2:

[0036] The difference between this comparative example and Example 1 is that isocyanate propyl triethoxysilane is replaced with an equal amount of phenyl triethoxysilane to prepare a phenyl triethoxysilane-modified phenolic resin; then the prepared modified material is used to prepare the corresponding composite material using the method of Example 1. During the process, the phenyl triethoxysilane-modified phenolic resin and the polysiloxane are phase separated after mixing, as shown in FIG. Figure 5 As shown (Figure A).

[0037] Comparative Example 3:

[0038] This comparative example is different from Example 1 in that isocyanate propyl triethoxysilane is replaced with an equal amount of methyl triethoxysilane to prepare a methyl triethoxysilane-modified phenolic resin, which is then used to prepare the corresponding composite material. During the process, the methyl triethoxysilane-modified phenolic resin and the polysiloxane are mixed, and the yellow phenolic resin agglomerates into particles, and after being placed at room temperature for 5 days, it is still a viscous paste and is difficult to solidify and form. Figure 5 As shown (Figure B).

Claims

1. A method for preparing a composite material of organosilicon-modified boron phenolic resin, characterized in that the method include: (1) boron phenolic resin and isocyanate propyl alkoxy silane react in a first organic solvent at 75-85° C. in the presence of organotin dilaurate to prepare organosilicon-modified boron phenolic resin; (2) At room temperature, the organosilicon-modified boron phenolic resin and the hydroxyl-terminated polymethylsiloxane are dissolved in a second organic solvent, mixed and heated to volatilize the second organic solvent, and after the second organic solvent is volatilized, dilaurate organotin is added, mixed and allowed to stand for reaction and degassing; and then cured at room temperature to obtain an organosilicon-modified boron phenolic resin composite material.

2. The method for preparing the organosilicon-modified boron phenolic resin composite material according to claim 1, characterized in that: The organotin dilaurate is selected from dibutyltin dilaurate.

3. The method for preparing the organosilicon-modified boron phenolic resin composite material according to claim 1, characterized in that: The isocyanate propyl alkoxy silane is selected from isocyanate propyl triethoxy silane.

4. The method for preparing the organosilicon-modified boron phenolic resin composite material according to claim 1, characterized in that: The mass ratio of the boron phenolic resin to the isocyanate propyl alkoxy silane is (50-20): (60-20).

5. The method for preparing the organosilicon-modified boron phenolic resin composite material according to claim 1, characterized in that: The first solvent is selected from ethanol, acetone or ethyl acetate, or a mixture of two or more thereof; the second solvent is selected from ethanol, acetone or ethyl acetate, or a mixture of two or more thereof.

6. The method for preparing the organosilicon-modified boron phenolic resin composite material according to claim 1, characterized in that: In step (1), the mass ratio of organotin dilaurate to isocyanate propyl alkoxy silane is 1:(50-1000).

7. The method for preparing the organosilicon-modified boron phenolic resin composite material according to claim 1, characterized in that: In step (2), the mass ratio of organotin dilaurate to hydroxyl-terminated polymethylsiloxane is 1:(50-500).

8. Use of the organosilicon-modified boron phenolic resin composite material prepared by the method of claim 1 as a heat-resistant protective material.

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