阅读说明：本技术 一种适用于热压罐始加压环氧树脂组合物的制备方法 (Preparation method of epoxy resin composition suitable for autoclave initial pressurization ) 是由 张琦 刘千立 张尉博 戴晶滨 徐小魁 姚卓君 张霞 唐靳梅 姚荐 王晓蕾 田杰 于 2019-12-20 设计创作，主要内容包括：本发明公开了一种适用于热压罐始加压环氧树脂组合物的制备方法；首先制备改性高温韧性环氧树脂,将改性高温韧性树脂与至少一种多官能团基体树脂熔融共混,在一定温度下,加入化学流变剂预聚反应一定时间得到混合物A；其次将固体芳香胺固化剂与液态双官能团树脂过三辊研磨机,使固化剂能在树脂中分散均匀得到混合物B,将混合物A和混合物B利用机械搅拌混合分散均匀得到环氧树脂组合物。该树脂体系玻璃化转变温度高、断裂韧性好、粘度粘性佳,高温最低粘度平台区适宜,且特别适用于制备碳纤维复合材料热压罐始加压成型工艺使用的热熔法预浸料。(The invention discloses a preparation method of an epoxy resin composition suitable for autoclave initial pressurization; firstly, preparing modified high-temperature tough epoxy resin, melting and blending the modified high-temperature tough epoxy resin and at least one polyfunctional group matrix resin, adding a chemical rheological agent at a certain temperature, and carrying out prepolymerization reaction for a certain time to obtain a mixture A; secondly, the solid aromatic amine curing agent and the liquid bifunctional resin are passed through a three-roll grinder, so that the curing agent can be uniformly dispersed in the resin to obtain a mixture B, and the mixture A and the mixture B are mechanically stirred, mixed and uniformly dispersed to obtain the epoxy resin composition. The resin system has high glass transition temperature, good fracture toughness, good viscosity and viscosity, and a suitable high-temperature minimum viscosity platform area, and is particularly suitable for preparing a hot-melt prepreg used in an autoclave initial pressure molding process of a carbon fiber composite material.)

1. The epoxy resin composition for the prepreg is characterized by comprising the following components in parts by weight:

15-50 parts of polyfunctional epoxy resin,

30-45 parts of bifunctional epoxy resin,

15-30 parts of aromatic amine curing agent,

15-40 parts of a toughening agent,

5-10 parts of chemical rheological agent.

2. The epoxy resin composition for prepreg according to claim 1, wherein the multifunctional epoxy resin is any one or a combination of 4,4 ' -diaminodiphenylmethane tetraglycidyl epoxy resin, 3 ' -diethyl-4, 4 ' -diaminodiphenylmethane tetraglycidyl epoxy resin, and triglycidyl-p-aminophenol epoxy resin.

3. The epoxy resin composition for prepreg according to claim 1, wherein the difunctional epoxy resin is any one or a combination of bisphenol F type epoxy resin, E51 type epoxy resin and E20 type solid epoxy resin.

4. The epoxy resin composition for prepreg according to claim 1, wherein the aromatic amine curing agent is any one or a combination of m-xylylenediamine, diaminodiphenylmethane, 3 '-diaminodiphenylsulfone, 4' -diaminodiphenylsulfone, and m-phenylenediamine.

5. The epoxy resin composition for prepreg according to claim 1, wherein the toughening agent is one or a combination of two of isocyanate modified epoxy resin and polyurethane modified epoxy resin at any ratio.

6. The epoxy resin composition for prepreg according to claim 1, wherein the chemical rheological agent is one or a combination of two of diaminodiphenylmethane and 3, 3' -diaminodiphenylsulfone.

7. The epoxy resin composition for prepreg according to claim 1, wherein the minimum viscosity of the viscothermo-rheological curve of the epoxy resin composition is not less than 2500mPa s, and the viscosity of the composition system is adjusted by pre-polymerization using the chemical rheological agent according to claim 6.

8. The epoxy resin composition for prepreg according to claim 1, wherein the aromatic amine curing agent is one of the difunctional epoxy resins as defined in claim 3, which is applied to a three-roll mill to uniformly disperse the aromatic amine curing agent in the composition system.

9. A method for preparing an epoxy resin composition suitable for use in an autoclave incipient pressure hot melt process for prepreg according to claim 1, comprising the steps of:

s1, mixing 15-50 parts of multifunctional epoxy resin, 12-22 parts of bifunctional epoxy resin and 15-40 parts of toughening agent, heating and stirring in an oil bath pot, adding 5-10 parts of chemical rheological agent when the material temperature is 125-135 ℃, and reacting for 120-150 min to obtain a transparent and uniform mixture A;

s2, mixing and stirring 15-30 parts of aromatic amine curing agent and the balance of bifunctional epoxy resin, and passing through a three-roll grinder for not less than 3 times to obtain a mixture B with the aromatic amine curing agent uniformly dispersed;

and S3, reducing the temperature of the material in the oil bath to 90-100 ℃, adding the mixture B into the mixture A, stirring at a high speed and mixing for 6-8min to obtain the epoxy resin composition.

10. The method for initial autoclave pressure molding of the epoxy resin composition for prepreg according to claim 1, wherein the epoxy resin composition is directly pressurized in a tank, and the vacuum bag pressure is discharged from-0.1 MPa to-0.02 MPa when the pressure is 0.1MPa, and the pressure is maintained after the pressure is continuously increased to 0.5 to 0.7 MPa.

Technical Field

The invention belongs to the technical field of carbon fiber composite materials, and particularly relates to a preparation method of an epoxy resin composition for prepreg by an autoclave initial pressurization hot melting method.

Background

At present, carbon fiber composite materials are adopted in a large amount for a spacecraft and a carrier to serve as key functional parts and structural parts, for example, the consumption of the carbon fiber composite materials in a domestic satellite structure reaches more than 90 percent, along with the development of a space detection technology, higher requirements are put forward on the reliability of the structural parts made of the composite materials, the reliability of the composite materials is improved, and prepreg for manufacturing the products is an important factor.

The manufacturing method of the prepreg is divided into a wet method and a hot melting method, wherein the wet method is a method for combining fibers with a solvent and a resin in a dipping device and then dipping the fibers; the hot-melting method is that firstly, a resin adhesive film with a certain width and uniform flatness is prepared, and then the prepared adhesive film is compounded with a certain amount of fibers at a certain temperature and under a certain pressure. Compared with a wet method, the hot-melt prepreg has the outstanding advantages of uniform resin distribution, accurate resin content control, low volatile content, good preparation environment (no solvent), high production efficiency and the like, but has high requirements on the technological properties of the resin, for example, the viscosity of the resin cannot be too low, and the viscosity can reach the effects of no brittleness in winter and no stickiness in summer.

At present, the domestic autoclave curing process is limited by the aspects of low viscosity, poor toughness and the like of a high-temperature viscosity area of a resin system for prepreg, and the process of pressurizing after heating to a specific temperature is mainly adopted, and the molding quality of a composite material member is directly determined by a pressurizing point. However, the pressing point is difficult to control and needs to be adjusted according to the characteristics of the component and the form of the die. And the pressure points of large-scale components are difficult to accurately control due to uneven temperature field distribution, so that the product quality has high fluctuation. In contrast, the autoclave initial pressurization process does not need to find a pressurization time, the autoclave is directly pressurized, the initial pressurization heat transfer effect is better than that of non-initial pressurization, the molding time and energy consumption of the composite material can be greatly saved, and the molding efficiency is improved.

Disclosure of Invention

The invention provides a preparation method of an epoxy resin composition for prepreg by an autoclave initial pressure hot melting method, aiming at overcoming the defect that the molding quality of a composite material member is greatly influenced by the pressing point of the existing autoclave molding process and widening the application field of the composite material.

In order to solve the problems, the invention adopts the following technical scheme:

the invention relates to an epoxy resin composition for prepreg, which is suitable for autoclave initial pressurization hot-melt method and comprises the following components in parts by weight: 15-50 parts of polyfunctional epoxy resin, 30-45 parts of bifunctional epoxy resin, 15-30 parts of aromatic amine curing agent, 15-40 parts of toughening agent and 5-10 parts of chemical rheological agent.

Further, the multifunctional epoxy resin is any one or a combination of more of 4,4 ' -diaminodiphenylmethane tetraglycidyl epoxy resin, 3 ' -diethyl-4, 4 ' -diaminodiphenylmethane tetraglycidyl epoxy resin and triglycidyl-p-aminophenol epoxy resin.

Further, the bifunctional epoxy resin is any one or a combination of more of bisphenol F type epoxy resin, E51 type epoxy resin and E20 type solid epoxy resin. The invention adds bifunctional epoxy resin to reduce the system cost, adjust the viscosity (wherein, E20 increases the viscosity), and reduce the reaction heat release of the resin system. If the bisphenol A polyether epoxy resin is replaced, the viscosity of the system is reduced, and the lowest viscosity of a high-temperature platform area required by the initial pressurization of an autoclave cannot be reached, so that the aim of the invention cannot be achieved.

Further, the aromatic amine curing agent is any one or a combination of several of m-xylylenediamine, diaminodiphenylmethane, 3 '-diaminodiphenyl sulfone, 4' -diaminodiphenyl sulfone and m-phenylenediamine.

Further, the toughening agent is isocyanate modified epoxy resin, polyurethane modified epoxy resin or a composition of two of the epoxy resin and the polyurethane modified epoxy resin in any proportion. The toughening agent used in the invention is not selected from conventional toughening agents, the toughening agent selected for the hot-melt prepreg is generally thermoplastic resin, and the toughening modification is mainly carried out by the thermoplastic resin such as polyether sulfone (PES), Polysulfone (PSF), polyether ether ketone (PEEK) and the like, but the thermoplastic resin has the disadvantages of large molecular weight, the viscosity of a resin system is increased rapidly in the processing process, the manufacturability and the paving property of the prepreg are deteriorated, and the wettability of the resin system to fiber bundles is also deteriorated, so that the requirements of the manufacturability of the invention cannot be met. The two toughening agents used in the invention are both toughening agents of modified epoxy resin, have good compatibility with matrix resin, do not generate phase separation, and achieve the purpose of toughening while maintaining the capability of improving the viscosity of a system.

Further, the chemical rheological agent is one or two of diaminodiphenylmethane and 3, 3' -diaminodiphenyl sulfone. The invention uses a small amount of curing agent with higher activity as chemical rheological agent, and increases the viscosity of a certain resin system through reaction, but reduces the reaction degree as much as possible.

Furthermore, the lowest viscosity of the viscosity-temperature rheological curve of the epoxy resin composition is more than or equal to 2500 mPa.s, and the viscosity of a resin system is adjusted by adopting one of the aromatic amine curing agents, namely a chemical rheological agent to carry out prepolymerization.

Furthermore, the aromatic amine curing agent can be uniformly dispersed in the composition system only by using one of the bifunctional epoxy resins as a master batch and passing the master batch through a three-roll grinder.

The invention also relates to a preparation method of the epoxy resin composition for the prepreg by the autoclave initial pressurization hot melt method, which comprises the following steps:

s1, mixing 15-50 parts of multifunctional epoxy resin, 12-22 parts of bifunctional epoxy resin and 15-40 parts of toughening agent, heating and stirring in an oil bath pot, adding 5-10 parts of chemical rheological agent when the material temperature is 125-135 ℃, and reacting for 120-150 min to obtain a transparent and uniform mixture A;

s2, mixing and stirring 15-30 parts of aromatic amine curing agent and the balance of bifunctional epoxy resin (such as E51 type epoxy resin), and passing through a three-roll grinder for at least 3 times to obtain a mixture B with the aromatic amine curing agent uniformly dispersed;

and S3, reducing the temperature of the material in the oil bath to 90-100 ℃, adding the mixture B into the mixture A, stirring at a high speed and mixing for 6-8min to obtain the epoxy resin composition.

Wherein the preferred stirring speed of the high-speed stirring and mixing is 1000-2000r/min, the stirring time is 6-8min, so that the aromatic amine curing agent can be fully and uniformly dispersed, and the epoxy resin composition for the prepreg, which is suitable for the autoclave initial pressure hot melting method, is obtained after full mixing.

In step S2, the remaining difunctional epoxy resin is E51 type epoxy resin.

The invention also relates to a method for performing autoclave initial pressure molding by using the epoxy resin composition for the prepreg by the autoclave initial pressure hot melting method, which comprises the steps of directly pressurizing the epoxy resin composition in a tank, unloading the vacuum bag pressure from-0.1 MPa to-0.02 MPa when the pressure is up to 0.1MPa, and maintaining the pressure after the pressure is continuously pressed to 0.5-0.7 MPa.

The epoxy resin composition of the present invention, which is suitable for the autoclave molding process, has the following two preferred molding processes for autoclave initial pressure molding.

Preferably, the autoclave is pressurized at the beginning, namely the autoclave is directly pressurized at normal temperature, and when the pressure is 0.1MPa, the vacuum bag pressure is unloaded from-0.1 MPa to-0.02 MPa. The flat plate skin composite material member is preferably pressed to 0.5MPa, the closed die type complex composite material member is preferably pressed to 0.7MPa, and the whole curing process is kept pressure.

Preferably, the heating rate is 1 ℃/min and 0.5 ℃/min, and the pressing rate is 0.04 MPa/min.

Compared with the existing autoclave forming technology, the invention has the beneficial effects that:

the initial-pressurization epoxy resin composition suitable for the autoclave not only increases the toughness of a resin system and improves the minimum viscosity of a high-temperature viscosity area, but also is not influenced by a pressurizing point to the molding quality of a composite material member, reduces the requirements of process personnel and curing operation personnel on the control of the pressurizing point, improves the product quality and stability, improves the production efficiency and reduces the production cost.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is an exemplary autoclave molding process;

fig. 2 is an example of an autoclave initial press molding process.

Detailed Description

The present invention will be described in detail with reference to examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be apparent to those skilled in the art that several modifications and improvements can be made without departing from the inventive concept. All falling within the scope of the present invention.

In the following examples, Shanghai Huayi resin Co., Ltd. (trade name AG-80) was selected as 4,4 ' -diaminodiphenylmethane tetraglycidyl epoxy resin, Shanghai Huayi resin Co., Ltd. (trade name AFG-90) was selected as triglycidyl p-aminophenol epoxy resin, Taiwan southern Asia resin Co., Ltd. (trade name NPEF-170) was selected as bisphenol F type epoxy resin, Shanghai resin factory was selected as E51 type epoxy resin, Jiaxing Aisen chemical Co., Ltd. was selected as diaminodiphenylmethane, Hebei New chemical Co., Ltd. was selected as 3,3 ' -diaminodiphenyl sulfone, Shanghai Saneisi reagent Co., Ltd. was selected as 4,4 ' -diaminodiphenyl sulfone, and Juzhou advanced materials institute (trade name OX-10) was selected as isocyanate-modified epoxy resin, the polyurethane modified epoxy resin is selected from Shanghai complexing high-tech materials Co., Ltd (trade name EPU-133). It should be noted that the multifunctional epoxy resin, the bifunctional epoxy resin, the aromatic amine curing agent and the toughening agent used in the present invention are not limited to the above-mentioned ones.