Solvent-free low-density phenolic resin prepreg matrix and preparation method thereof

Abstract

The invention relates to a solvent-free low-density phenolic resin prepreg matrix and a preparation method thereof, and belongs to the high and new technical field of thermal protection of lightweight aerospace, weaponry, transportation and the like. The low-density phenolic resin prepreg matrix is prepared from the following components in parts by mass: 100 parts of phenolic resin, 10 to 60 parts of low-density filler, 10 to 50 parts of high-temperature-resistant diluent and 5 to 30 parts of thermoplastic toughening agent. The invention also discloses a phenolic resin prepreg containing the low-density phenolic resin prepreg matrix, and a preparation method of the low-density phenolic resin prepreg. The phenolic resin prepreg matrix prepared by the invention is solvent-free, low in density, high in carbon yield and suitable for a composite material prepreg process; and meanwhile, the method has the advantages of good environmental protection property, excellent product quality, high material utilization rate and the like, and has wide application prospects. The preparation process is simple, low in cost and convenient to operate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of phenolic resin and its preparation, in particular to a low-density (high-performance) phenolic resin prepreg matrix and its preparation method by a solvent-free method, and especially to a prepreg process for large composite structural parts. BACKGROUND

[0002] The thermal protection system (TPS) is a key system for protecting various components serving in high-temperature environments from burning or overheating. Among them, the ablative thermal protection material is a kind of active thermal protection method that reduces heat by sacrificing the mass of the thermal protection material itself to carry away a large amount of aerodynamic heat.

[0003] The ablative material is usually composed of a resin with low thermal conductivity impregnated into a three-dimensional fibrous preform or a honeycomb reinforced structure with high porosity and low thermal conductivity. The low-density resin decomposes at high temperatures to produce pyrolytic carbon and pyrolysis gas, which reduces the convective heat flux on the ablative surface and the reverse radiation effect of the pyrolytic carbon layer with high emissivity, thereby dissipating heat. In addition, the low thermal conductivity of the material can maintain a low internal temperature of the ablative material for a long time.

[0004] Currently, the main means to achieve lightweight materials is by adding low-density fillers. Chinese patent application CN202311722540.6 successfully obtains a low-density phenolic prepreg matrix by adding 5% to 60% glass hollow microspheres to the phenolic resin. However, the addition of organic solvents to disperse the glass microspheres is used to prevent agglomeration. However, the presence of solvents in the prepreg system may lead to inaccurate control of the glue content, material waste, and environmental problems such as gas emissions, thereby limiting the application of the material. SUMMARY

[0005] To solve the above technical problems, the purpose of the present application is to provide a low-density high-performance phenolic resin prepreg matrix and its preparation method. The preparation method is solvent-free and suitable for prepreg molding process.

[0006] The purpose of the present application is achieved by the following technical solutions: In a first aspect, the present application provides a low-density phenolic resin prepreg matrix, which comprises the following components by mass fraction: 100 parts of phenolic resin, 10 to 60 parts of low-density filler, 10 to 50 parts of high-temperature resistant diluent, and 5 to 30 parts of thermoplastic toughening agent.

[0007] As some specific embodiments of the present application, the phenolic resin is selected from one or more of barium phenolic, boron phenolic, magnesium phenolic, and ammonia phenolic.

[0008] As some specific embodiments of the present invention, the low-density filler includes at least one of glass microspheres or phenolic microspheres, and the density of the low-density filler is 0.1~0.9 g / cm³. 3 The glass microspheres include hollow glass microspheres.

[0009] As some specific embodiments of the present invention, the high-temperature resistant diluent is selected from one or more of polyfunctional glycidyl ethers, phenolic glycidyl ethers, naphthyl glycidyl ethers, and cyanate ester resins.

[0010] Specifically, the multifunctional glycidyl ether includes one or more of trimethylolpropane triglycidyl ether, aminophenol trifunctional epoxy resin, and amino tetrafunctional epoxy resin. And / or, the phenolic glycidyl ethers include one or more of resorcinol diglycidyl ether and o-cresol glycidyl ether; And / or, the cyanate resin includes one or more of bisphenol A, bisphenol E, and bisphenol M cyanate.

[0011] High-temperature resistant diluents can reduce the viscosity of the system, which not only alleviates the drying problem after adding low-density fillers, but also increases the threshold of filler specific gravity as much as possible, making the system density range wider. On the other hand, they can increase the viscosity of the system. Phenolic resin has low viscosity due to its structure, resulting in poor processability for preparing prepregs. Furthermore, the viscosity drops sharply after adding fillers, making it impossible to prepare prepregs. However, the addition of diluents makes the system viscous at room temperature, which satisfies the requirements for prepreg coverage.

[0012] As some specific embodiments of the present invention, the thermoplastic toughening agent is selected from one or more of polyvinyl butyral, nitrile rubber, styrene-butadiene rubber, polyurethane, polypropylene, polyphenylene sulfone, polysulfone, and polyethersulfone. The main purpose of adding the toughening agent to the solvent-free system of the present invention is to increase the film-forming properties of the prepreg.

[0013] The addition of high-temperature resistant diluent and thermoplastic toughening agent solves the problems of excessive viscosity and loss of resin film-forming properties caused by the addition of hollow microspheres. The synergistic use of the two can reduce the viscosity of the system and improve film-forming properties.

[0014] In a second aspect, the present invention provides a low-density phenolic resin prepreg, comprising the low-density phenolic resin prepreg matrix as described in any one of the above claims, and fibers.

[0015] As some specific embodiments of the present invention, the fiber is selected from at least one of glass fiber, aramid fiber, and quartz fiber.

[0016] As some specific embodiments of the present invention, the mass percentage of the low-density phenolic resin prepreg matrix in the low-density phenolic resin prepreg is 20-50%.

[0017] Thirdly, the present invention provides a method for preparing a low-density phenolic resin prepreg as described in any of the preceding claims, comprising the following steps: S1. Mix the high-temperature resistant diluent and the thermoplastic toughening agent evenly according to the mass fraction to obtain component A; S2. By mass fraction, first add component A to phenolic resin (component B) and stir to mix evenly. Then add low-density filler (component C) to the mixing system and stir to mix evenly to obtain low-density phenolic resin prepreg matrix. S3. The low-density phenolic resin prepreg matrix is ​​combined with fibers and cured to obtain low-density phenolic resin prepreg.

[0018] As some specific embodiments of the present invention, in step S1, the stirring and mixing is carried out at a temperature of 80~150°C.

[0019] As some specific embodiments of the present invention, in step S3, the curing is carried out in a stepwise curing process within a temperature range of 90~160℃, and the curing time is 2~10h.

[0020] Thirdly, the present invention provides the application of the low-density phenolic resin prepreg as described in any of the preceding claims in the preparation of aircraft heat shields, fairings, and heat shield covers.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1) The prepreg prepared by the solvent-free method of this invention has environmentally friendly characteristics, as well as the advantages of accurate control of the resin content (mass ratio of resin matrix in prepreg) and excellent product quality. It is suitable for the prepreg process of large composite material structural parts and has broad application prospects.

[0022] 2) Selecting phenolic resin with a high char residue rate and adding low-density filler can reduce the system density while forming uniform pores and reducing the thermal conductivity of the material. At the same time, the addition of high-temperature resistant diluent can reduce the system thickening problem caused by filler; in addition, thermoplastic toughening agent can increase the film-forming properties and toughness of the resin. The addition of these two materials can reduce the problem of loss of viscosity and film-forming properties caused by low-density filler in solvent-free systems.

[0023] 3) The preparation method used in this invention is simple to operate and widely applicable; the density of the prepared resin formulation is <1.0 g / cm³. 3 The residual carbon rate after thermal weight loss at 800℃ is ≥50%.

[0024] 4) The high-temperature resistant diluent in the material system of the present invention can reduce the viscosity of the system. This not only alleviates the drying problem after the addition of low-density fillers, but also increases the threshold of filler specific gravity as much as possible, making the system density range wider. On the other hand, it can increase the viscosity of the system. Phenolic resin has low viscosity due to its structure, resulting in poor processability for preparing prepregs. Furthermore, the viscosity decreases sharply after the addition of fillers, making it impossible to prepare prepregs. The addition of the diluent makes the system still viscous at room temperature, satisfying the prepreg coverage. Attached Figure Description

[0025] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 The graph shows the thermogravimetric results of Example 3. Detailed Implementation

[0026] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0027] Example 1 (1) By mass, 50 parts of resorcinol diglycidyl ether high-temperature resistant diluent and 10 parts of styrene-butadiene rubber toughening agent are stirred and mixed evenly at 80°C to obtain component A; (2) By mass, first add component A to 100 parts of phenolic resin and stir until evenly mixed, then add 60 parts of phenolic resin with a density of 0.25 g / cm³. 3 Hollow glass microspheres are added to the mixing system and stirred until homogeneous to obtain the resin matrix.

[0028] (3) The above resin matrix is ​​cast into a mold and cured by holding at 100℃ for 1 hour, 120℃ for 3 hours, and 150℃ for 2 hours to obtain the resin cured product, namely the phenolic resin prepreg matrix.

[0029] Example 2 (1) By mass, 50 parts of resorcinol diglycidyl ether high-temperature resistant diluent and 10 parts of styrene-butadiene rubber toughening agent are stirred and mixed evenly at 100°C to obtain component A; (2) By mass, first add component A to 100 parts of boron phenolic resin and stir until evenly mixed, then add 50 parts of 0.25 g / cm³ density... 3 Hollow glass microspheres are added to the mixing system and stirred until homogeneous to obtain the resin matrix.

[0030] (3) The above resin formula is poured into the mold and cured according to the following conditions: 100℃ for 1 hour, 120℃ for 3 hours, and 150℃ for 2 hours, to obtain the cured resin.

[0031] Example 3 (1) By mass, 50 parts of resorcinol diglycidyl ether high-temperature resistant diluent and 10 parts of styrene-butadiene rubber toughening agent are stirred and mixed evenly at 100°C to obtain component A; (2) By mass, first add component A to 100 parts of boron phenolic resin and stir until evenly mixed, then add 40 parts of 0.25 g / cm³... 3 Hollow glass microspheres are added to the mixing system and stirred until homogeneous to obtain the resin matrix.

[0032] (3) The above resin formula is poured into the mold and cured according to the following conditions: 100℃ for 1 hour, 120℃ for 3 hours, and 150℃ for 2 hours, to obtain the cured resin.

[0033] Example 4 (1) By mass, 50 parts of resorcinol diglycidyl ether high-temperature resistant diluent and 10 parts of styrene-butadiene rubber toughening agent are stirred and mixed evenly at 100°C to obtain component A; (2) By mass, first add component A to 100 parts of boron phenolic resin and stir until evenly mixed, then add 30 parts of 0.25 g / cm³... 3 Hollow glass microspheres are added to the mixing system and stirred until homogeneous to obtain the resin matrix.

[0034] (3) The above resin formula is poured into the mold and cured according to the following conditions: 100℃ for 1 hour, 120℃ for 3 hours, and 150℃ for 2 hours, to obtain the cured resin.

[0035] Example 5 (1) By mass, 50 parts of resorcinol diglycidyl ether high-temperature resistant diluent and 10 parts of styrene-butadiene rubber toughening agent are stirred and mixed evenly at 100°C to obtain component A; (2) By mass, first add component A to 100 parts of boron phenolic resin and stir until evenly mixed, then add 20 parts of 0.25 g / cm³... 3 Hollow glass microspheres are added to the mixing system and stirred until homogeneous to obtain the resin matrix.

[0036] (3) The above resin formula is poured into the mold and cured according to the following conditions: 100℃ for 1 hour, 120℃ for 3 hours, and 150℃ for 2 hours, to obtain the cured resin.

[0037] Comparative Example 1 Based on Example 1, 50 parts of resorcinol diglycidyl ether high-temperature resistant diluent were removed from the formula, and the remaining steps and parameters were carried out in accordance with Example 1.

[0038] Comparative Example 2 Based on Example 1, the mass fraction of resorcinol diglycidyl ether high-temperature resistant diluent was increased from 50 parts to 70 parts, and the remaining steps and parameters were carried out in accordance with Example 1.

[0039] Performance test examples (I) Thermogravimetric analysis Thermogravimetric analysis was performed on the product prepared in Example 3. The repeated experimental data are shown in Table 1, and the thermogravimetric curves of Examples 3-2 are shown in Table 1. Figure 1 .Depend on Figure 1 As shown in Table 1, the initial decomposition temperature (T) of the cured resin is... 5% The temperature of all samples was greater than 330℃, and the carbon residue at 800℃ was greater than 50%, indicating that the resin has excellent thermal stability and good ablation resistance.

[0040] Table 1 Thermal property data of the cured product of the formulation in Example 3

[0041] (ii) Density test The density of the cured products from Examples 1-5 was tested using the water displacement method, and the relevant data are shown in Table 2. As shown in Table 2, the density of the prepared cured resin is less than 1.0 g / cm³. 3 It has extremely low density, and the prepreg prepared with the reinforcement has the advantage of low density and lightweight.

[0042] Table 2 Density data of cured products from Examples 1-5

[0043] (III) Process and viscosity testing The processability and viscosity of the phenolic resin prepreg matrices prepared in Example 1, Comparative Examples 1 and 2 were evaluated, and the results are shown in Table 3 below: Table 3 Process and viscosity of cured products from the examples and comparative formulations

[0044] (Note: The + in the table above indicates the degree of processability and adhesion.) As can be seen from the table above, adding an appropriate amount of high-temperature resistant diluent to the solvent-free formulation system of the present invention can significantly improve the processability and viscosity of the obtained cured product.

[0045] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A low-density phenolic resin prepreg matrix, characterized in that, By weight, it includes the following components: 100 parts phenolic resin, 10-60 parts low-density filler, 10-50 parts high-temperature resistant diluent, and 5-30 parts thermoplastic toughening agent.

2. The low-density phenolic resin prepreg matrix according to claim 1, characterized in that, The phenolic resin is selected from one or more of barium phenolic resin, boron phenolic resin, magnesium phenolic resin, and aminophenolic resin.

3. The low-density phenolic resin prepreg matrix according to claim 1, characterized in that, The low-density filler includes at least one of glass microspheres or phenolic microspheres, and the density of the low-density filler is 0.1~0.9 g / cm³. 3 .

4. The low-density phenolic resin prepreg matrix according to claim 1, characterized in that, The high-temperature resistant diluent is selected from one or more of the following: multifunctional glycidyl ether, phenolic glycidyl ether, naphthyl glycidyl ether, and cyanate ester resin; The multifunctional glycidyl ether includes one or more of trimethylolpropane triglycidyl ether, aminophenol trifunctional epoxy resin, and amino tetrafunctional epoxy resin. And / or, the phenolic glycidyl ethers include one or more of resorcinol diglycidyl ether and o-cresol glycidyl ether; And / or, the cyanate resin includes one or more of bisphenol A, bisphenol E, and bisphenol M cyanate.

5. The low-density phenolic resin prepreg matrix according to claim 1, characterized in that, The thermoplastic toughening agent is selected from one or more of polyvinyl butyral, styrene-butadiene rubber, polypropylene, and polyethersulfone.

6. A low-density phenolic resin prepreg, characterized in that, It includes the low-density phenolic resin prepreg matrix and fibers as described in any one of claims 1-5.

7. The low-density phenolic resin prepreg according to claim 6, characterized in that, The fiber includes any one of quartz fiber, aramid fiber, and glass fiber; And / or, in the low-density phenolic resin prepreg, the mass percentage of the low-density phenolic resin prepreg matrix is ​​20-50%.

8. A method for preparing a low-density phenolic resin prepreg as described in claim 6 or 7, characterized in that, Includes the following steps: S1. Mix the high-temperature resistant diluent and the thermoplastic toughening agent evenly according to the mass fraction to obtain component A; S2. By mass fraction, first add component A to the phenolic resin and stir until uniform, then add the low-density filler to the mixture and stir until uniform to obtain the low-density phenolic resin prepreg matrix. S3. The low-density phenolic resin prepreg matrix is ​​combined with fibers and cured to obtain low-density phenolic resin prepreg.

9. The preparation method according to claim 8, characterized in that, In step S1, the stirring and mixing are carried out at a temperature of 80~150℃; And / or, in step S3, the curing is performed in a stepwise curing process within a temperature range of 90~160℃, and the curing time is 2~6 hours.

10. The application of a low-density phenolic resin prepreg as described in claim 6 or 7 in the preparation of aircraft heat shields, fairings, and heat shield covers.

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