阅读说明：本技术 一种热熔环氧树脂及预浸料的制备方法和应用 (Hot-melt epoxy resin and preparation method and application of prepreg ) 是由 师慧 吴斌 侯锋辉 韩笑 王�华 孔娜 李博 郑桂宁 于 2019-11-28 设计创作，主要内容包括：本发明公开了一种热熔环氧树脂,通过先加入固化剂进行加热保温预固化处理,调节聚合物粘度,然后降温并加入固化剂成型制备得到；本发明还公开了一种预浸料的制备方法,以热熔环氧树脂为原料,采用热熔法中的膜胶压延法制备预浸料；本发明还公开了一种预浸料的应用,将预浸料铺贴后采用模压法成型,冷却后得到预浸料层压板。本发明的热熔环氧树脂的成膜性和浸渍能较好,避免了多组分配料和混料不均匀对产品性能的不良影响,有利于工业自动化生产；本发明预浸料的制备方法提高了预浸料中的含胶量均匀性,制备的预浸料在室温下粘结性好,操作方便；本发明的预浸料的应用工艺简单,制备条件温和,容易实现,进一步扩大了本发明预浸料的应用范围。(The invention discloses a hot-melt epoxy resin which is prepared by adding a curing agent for heating, heat-preserving and pre-curing treatment, adjusting the viscosity of a polymer, then cooling and adding the curing agent for molding; the invention also discloses a preparation method of the prepreg, which takes the hot-melt epoxy resin as a raw material and adopts a film adhesive calendering method in the hot-melt method to prepare the prepreg; the invention also discloses application of the prepreg, wherein the prepreg is molded by a mould pressing method after being paved and attached, and a prepreg laminated board is obtained after cooling. The hot-melt epoxy resin has good film forming property and impregnating property, avoids adverse effects of uneven multi-component ingredients and mixed materials on product performance, and is beneficial to industrial automatic production; the preparation method of the prepreg improves the uniformity of the content of the gel in the prepreg, and the prepared prepreg has good cohesiveness at room temperature and is convenient to operate; the prepreg has the advantages of simple application process, mild preparation conditions and easy realization, and further expands the application range of the prepreg.)

1. The hot-melt epoxy resin is characterized by being prepared from the following raw materials in parts by mass: 100 parts of liquid epoxy resin, 3.5-4.0 parts of aromatic amine curing agent A and 26.7-27.3 parts of aromatic amine curing agent B; the thermal deformation temperatures of the aromatic amine curing agent A and the aromatic amine curing agent B reach 150 ℃, the thermal deformation temperature of the aromatic amine curing agent B is higher than that of the aromatic amine curing agent A, and the latency of the aromatic amine curing agent B in the epoxy resin is superior to that of the aromatic amine curing agent A in the epoxy resin; the hot-melt epoxy resin is prepared by the following steps:

step one, heating and insulating liquid epoxy resin;

step two, adding an aromatic amine curing agent A into the liquid epoxy resin heated and insulated in the step one, uniformly stirring, heating to 150-160 ℃, and keeping the temperature for 100-120 min to perform pre-curing treatment to obtain a polymer;

and step three, cooling the polymer obtained in the step two to 90-100 ℃, then adding the aromatic amine curing agent B in batches, uniformly stirring, and cooling to room temperature to obtain the hot-melt epoxy resin.

2. A hot melt epoxy resin according to claim 1, wherein said liquid epoxy resin is E51 epoxy resin.

3. The hot-melt epoxy resin as claimed in claim 1, wherein the aromatic amine-based curing agent A is a DDM curing agent.

4. The hot-melt epoxy resin as claimed in claim 1, wherein the aromatic amine-based curing agent B is a DDS curing agent.

5. The hot-melt epoxy resin as claimed in claim 1, wherein the heating temperature in the first step is 50-60 ℃ and the holding time is 20-30 min.

6. A hot-melt epoxy resin according to claim 1, wherein the number of said additions in step three is 3.

7. A method for preparing a prepreg by using the hot-melt epoxy resin as claimed in any one of claims 1 to 6, which is characterized in that the prepreg is prepared by using a film adhesive calendering method in a hot-melt method, and the specific process is as follows: the molten hot-melt epoxy resin is uniformly coated on the gumming paper on a coating machine to prepare a film, then the fiber/fabric is clamped between two rolls of films on a dipping machine to form a sandwich structure, and the films are dipped into the fiber/fabric through a hot roller to obtain the prepreg.

8. The method as claimed in claim 7, wherein the temperature of the coating machine rubber roller is 60-65 ℃, and the whole linear speed is 3-5 m/min; the temperature of the hot roller of the impregnation machine is 65-70 ℃, and the linear speed is 3-5 m/min.

9. The use of a prepreg according to claim 7 wherein the prepreg is applied and formed by compression moulding and cooled to provide a prepreg laminate; the specific process of molding by the die pressing method comprises the following steps: firstly heating to 90-100 ℃ and preserving heat for 20-30 min at the pressure of 0.1-0.3 MPa, then heating to 190-200 ℃ and preserving heat for 120-150 min at the pressure of 0.3-0.5 MPa.

10. Use according to claim 9, wherein the prepreg is a glass fibre prepreg.

Technical Field

The invention belongs to the technical field of prepreg preparation, and particularly relates to hot-melt epoxy resin, and a preparation method and application of prepreg.

Background

The resin-based composite material has the characteristics of strong manufacturability, good mechanical property, excellent thermophysical and physical properties and the like. The epoxy resin is a resin matrix which is most widely applied to resin-based composite materials, and has excellent manufacturability, heat resistance, chemical resistance, mechanical property and electrical property, so that the epoxy resin is widely applied to the fields of aerospace and the like. The epoxy resin is a polymer containing more than two epoxy groups in the molecule, is cured and crosslinked by adopting a curing agent to generate a network structure, and belongs to thermosetting resin. Along with the application of the resin in the aerospace field, higher requirements are put on the heat resistance of the resin, and the glass transition temperature of the aerospace-grade resin is required to be more than 150 ℃.

The prepreg is a composition of a resin matrix and a reinforcement prepared by impregnating a resin matrix with continuous fibers or fabrics under strictly controlled conditions, is an intermediate for manufacturing advanced composite materials, has a structural unit with certain mechanical properties, can be subjected to structural design, and is directly transplanted into a composite material product with certain properties. The prepreg can be produced by a solution method (wet method) and a hot-melt method (dry method). The solution method is the first method for manufacturing the prepreg, namely, the resin is dissolved in a solvent (such as ethanol and acetone) with low boiling point to form the prepreg, and the method has the defects of uneven gel content, environmental pollution and the like; the hot melting method is to melt resin at high temperature, and then carbon fibers or fabrics are impregnated in different modes to prepare prepreg, the prepared prepreg has uniform and easily-controlled content, no solvent, low volatile matter content, no environmental pollution, good appearance quality of finished products and increasingly wide and deep application, so the research on the hot melting method has been a hotspot. According to the process steps, the hot melting method can be divided into a direct hot melting method and a film adhesive calendering method, wherein the fiber is directly immersed into the molten resin; the latter is to make resin into glue film, compound on the surface of fiber, then heat and pressurize to melt the resin, and immerse into fiber. The film adhesive calendering method is the most widely applied method at the present stage, and requires that the resin has good film forming property in a room temperature environment and has good wettability and adhesiveness to fibers at a certain temperature.

In general, a method for synthesizing a hot-melt epoxy resin for a prepreg includes mixing a liquid resin and a solid resin to adjust the viscosity and specific properties of the resin, and adding a curing agent and an accelerator. In general, in a hot-melt resin formula, liquid epoxy resin is taken as a matrix (such as E51), and then cured epoxy resin is added to adjust viscosity (increase viscosity), so that the resin is in a semi-solid state at normal temperature and is not sticky, and the prepared prepreg is easy to operate; on the other hand, the resin viscosity is required to be semi-solid at normal temperature, and when the fiber or fabric is impregnated after hot melting, the viscosity in the process window is required to be good for the impregnation of the fiber or fabric (the film formation is also required to be good by a film adhesive calendering method), and the applicable viscosity of the existing equipment is required to be 7 pas to 70 pas. The patent application No. 201510023408.5 discloses a method for preparing colorless transparent epoxy resin for prepreg and composite material, which comprises using liquid epoxy resin, solid epoxy resin, curing agent and accelerator as components, and adjusting the ratio of the liquid epoxy resin and the solid epoxy resin to adjust the viscosity of the colorless transparent epoxy resin, wherein the glass transition temperature of the obtained prepreg is 145-150 ℃, and the heat resistance is general. The patent with the application number of 201610365714.1 discloses a high-temperature-resistant cured epoxy resin carbon fiber prepreg, and a preparation method and application thereof, wherein the viscosity is adjusted by adjusting the proportion of liquid epoxy resin and solid epoxy resin, and the prepared prepreg has good heat resistance, but is realized by adding high-temperature-resistant epoxy resin.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a hot-melt epoxy resin, which is used for overcoming the defects of the prior art. The hot-melt epoxy resin is prepared by firstly adding the curing agent to carry out heating and heat-preservation pre-curing treatment, adjusting the viscosity of a polymer, then cooling and adding the curing agent to carry out forming, so that the material loss caused by the batching times is reduced, the adverse effects of errors and uneven material mixing in the calculation process of multi-component batching on the performance of products are avoided, the industrial automatic production is facilitated, the hot-melt epoxy resin is in a semi-solid state at room temperature and is not sticky, the film-forming property after heating is better, and the impregnation property on continuous fibers/fabrics is better.

In order to solve the technical problems, the invention adopts the technical scheme that: the hot-melt epoxy resin is characterized by being prepared from the following raw materials in parts by mass: 100 parts of liquid epoxy resin, 3.5-4.0 parts of aromatic amine curing agent A and 26.7-27.3 parts of aromatic amine curing agent B; the thermal deformation temperatures of the aromatic amine curing agent A and the aromatic amine curing agent B reach 150 ℃, the thermal deformation temperature of the aromatic amine curing agent B is higher than that of the aromatic amine curing agent A, and the latency of the aromatic amine curing agent B in the epoxy resin is superior to that of the aromatic amine curing agent A in the epoxy resin; the hot-melt epoxy resin is prepared by the following steps:

step one, heating and insulating liquid epoxy resin;

step two, adding an aromatic amine curing agent A into the liquid epoxy resin heated and insulated in the step one, uniformly stirring, heating to 150-160 ℃, and keeping the temperature for 100-120 min to perform pre-curing treatment to obtain a polymer;

and step three, cooling the polymer obtained in the step two to 90-100 ℃, then adding the aromatic amine curing agent B in batches, uniformly stirring, and cooling to room temperature to obtain the hot-melt epoxy resin.

The method comprises the steps of heating and insulating liquid epoxy resin to enhance stirring performance, adding the aromatic amine curing agent A, heating and insulating to perform pre-curing adjustment to increase viscosity to obtain a polymer, cooling, and adding the aromatic amine curing agent B to avoid an implosion phenomenon caused by an exothermic reaction between the liquid epoxy resin and the aromatic amine curing agent A, so that the hot-melt epoxy resin with excellent heat resistance is obtained, is semi-solid at room temperature and is not sticky, and has good film forming performance after heating and good impregnation performance on continuous fibers/fabrics.

The above hot-melt epoxy resin is characterized in that the liquid epoxy resin is E51 epoxy resin. The liquid epoxy resin is a general liquid epoxy resin, has good performances of adhesion, corrosion resistance, insulation and high strength, is low in price and is easy to obtain.

The hot-melt epoxy resin is characterized in that the aromatic amine curing agent A is a DDM curing agent. The DDM curing agent has good heat resistance and is easy to obtain.

The hot-melt epoxy resin is characterized in that the aromatic amine curing agent B is a DDS curing agent. The DDS curing agent has better heat resistance and the heat resistance is better than that of the common DDM curing agent.

The hot-melt epoxy resin is characterized in that the heating temperature in the step one is 50-60 ℃, and the heat preservation time is 20-30 min. The optimized heating parameters improve the fluidity of the liquid epoxy resin after heating and heat preservation, and are beneficial to mutual solubility of the subsequent liquid epoxy resin and the curing agent.

The hot-melt epoxy resin is characterized in that the adding times in the step three are 3 times. As the liquid epoxy resin is added with the aromatic amine curing agent A and the aromatic amine curing agent B, the reactions are exothermic, and the aromatic amine curing agent B is added by times, particularly by 3 times, the cooled polymer and the aromatic amine curing agent B are fully stirred and uniformly dispersed, so that the phenomenon of implosion caused by excessive heat accumulation is avoided, and the preparation of the hot-melt epoxy resin is prevented from being influenced.

In addition, the invention also discloses a method for preparing the prepreg by adopting the hot-melt epoxy resin, which is characterized in that the prepreg is prepared by adopting a film adhesive calendering method in the hot-melt method, and the specific process is as follows: the molten hot-melt epoxy resin is uniformly coated on the gumming paper on a coating machine to prepare a film, then the fiber/fabric is clamped between two rolls of films on a dipping machine to form a sandwich structure, and the films are dipped into the fiber/fabric through a hot roller to obtain the prepreg.

The prepreg is prepared by adopting a film adhesive calendering method in a hot melting method, and the fiber/fabric is clamped between two rolls of films made of hot-melt epoxy resin to form a sandwich structure, so that the uniformity of the content of the adhesive in the prepreg is improved, and the prepared prepreg has good cohesiveness at room temperature and is convenient to operate.

The method is characterized in that the temperature of the rubber roller of the coating machine is 60-65 ℃, and the whole linear speed is 3-5 m/min; the temperature of the hot roller of the impregnation machine is 65-70 ℃, and the linear speed is 3-5 m/min. The optimized technological parameters in the preparation process are beneficial to uniformly coating the molten hot-melt epoxy resin on the impregnated paper to prepare a film with uniform thickness, ensure that the film is fully immersed into the fiber/fabric, and further improve the uniformity of the content of the glue in the prepreg.

The invention also provides application of the prepreg, which is characterized in that the prepreg is molded by adopting a mould pressing method after being laid and pasted, and a prepreg laminated board is obtained after cooling; the specific process of molding by the die pressing method comprises the following steps: firstly heating to 90-100 ℃ and preserving heat for 20-30 min at the pressure of 0.1-0.3 MPa, then heating to 190-200 ℃ and preserving heat for 120-150 min at the pressure of 0.3-0.5 MPa.

The invention adopts a mould pressing method to prepare the prepreg into the prepreg laminated board, has simple process, mild preparation conditions and easy realization, and further enlarges the application range of the prepreg.

The application is characterized in that the prepreg is a glass fiber prepreg. The preparation method can be applied to common glass fiber prepreg, and the glass fiber prepreg laminated board is prepared by taking the common glass fiber prepreg as a raw material, so that the practical performance and the application value of the invention are enlarged.

Compared with the prior art, the invention has the following advantages:

1. compared with the prior art that the viscosity is adjusted by adjusting the ratio of liquid resin to solid resin in the prepared components, the invention obtains the hot-melt epoxy resin with excellent heat resistance by adding the curing agent for heating, heat-preserving and pre-curing treatment, adjusting the viscosity of the polymer, then cooling and adding the curing agent for molding, reduces the material loss caused by the batching frequency, avoids the adverse effects of errors and uneven mixing in the multi-component batching calculation process on the product performance, and is beneficial to industrial automatic production.

2. According to the invention, through the selection of the proportion of the resin and the curing agent, the prepared hot-melt epoxy resin is semisolid at room temperature and is not sticky, the film-forming property after heating is better, and the impregnation property on continuous fibers/fabrics is better.

3. The prepreg is prepared by adopting a film adhesive calendering method in a hot melting method, and the fiber/fabric is clamped between two rolls of films made of hot-melt epoxy resin to form a sandwich structure, so that the uniformity of the content of the adhesive in the prepreg is improved, and the prepared prepreg has good cohesiveness at room temperature and is convenient to operate.

4. The invention firstly prepares the glass fiber prepreg, and then prepares the glass fiber prepreg into the glass fiber laminated board by adopting a mould pressing method, the glass transition temperature of the glass fiber laminated board can reach more than 180 ℃, the heat resistance is good, and the use requirement in high temperature environment is greatly met.

5. The glass fiber board laminated board prepared by the invention has no adverse phenomena of layering, pores, rich grease, poor glue, debonding, deformation and the like, and the finally prepared product meets the standard requirement.

The technical solution of the present invention is further described in detail by examples below.

Detailed Description