Epoxy resin system for low-viscosity high-Tg prepreg yarn and preparation method of epoxy resin system

Abstract

The invention relates to the technical field of resin preparation, in particular to an epoxy resin system for low-viscosity high-Tg prepreg yarn and a preparation method thereof.The epoxy resin system is prepared from, by weight, 60-80 parts of epoxy resin A, 20-40 parts of epoxy resin B, 1-3 parts of diluent and 6-10 parts of epoxy curing agent; the epoxy resin A is formed by carrying out polycondensation on thermoplastic linear phenolic resin with low relative molecular mass and epoxy chloropropane under the action of alkali; the diluent is used for reducing the viscosity of an epoxy system and improving the wettability and fluidity of the epoxy resin system. According to the device, the epoxy resin A is arranged, so that the advantages of no hand sticking and high viscosity of a resin system at room temperature can be ensured, and the low softening point can ensure that the viscosity of the resin system is 2000cp or below when the resin system is heated to 80 DEG C.

Description

Technical Field

[0001] The invention relates to the field of resin preparation, and in particular to an epoxy resin system for low-viscosity and high-Tg prepreg yarn and a preparation method thereof. Background Art

[0002] With the rapid development of aerospace technology, the demand for high-performance composite materials is increasing. Prepreg yarn is an important component of composite materials, and its performance directly affects the quality and performance of the final composite materials. The epoxy resin system is a component of the prepreg yarn matrix. Its own viscosity affects the viscosity of the prepreg yarn and the impregnation effect. The glass transition temperature of the epoxy resin system determines the use environment, etc. The performance of the epoxy resin system affects the performance of the prepreg yarn. Therefore, different epoxy resin systems need to be combined according to the use environment and requirements.

[0003] At present, most of the epoxy resin systems for prepreg yarns on the market are general-purpose epoxy resin systems, which have many disadvantages. In addition, the epoxy resin system has a low glass transition temperature that cannot meet the use requirements, while the high glass transition temperature requires a high curing temperature. These factors determine that the material cannot be used in some fields or environments with special requirements. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a low-viscosity high-Tg prepreg epoxy resin system and a preparation method thereof.

[0005] In a first aspect, the present invention provides an epoxy resin system for low-viscosity and high-Tg prepreg yarn, comprising the following raw materials in parts by weight:

[0006] Epoxy resin A: 60-80 parts, epoxy resin B: 20-40 parts, diluent: 1-3 parts, epoxy curing agent: 6-10 parts;

[0007] The epoxy resin A is prepared by polycondensation of a low molecular weight thermoplastic linear phenolic resin and epichlorohydrin under the action of an alkali;

[0008] The diluent is used to reduce the viscosity of the epoxy system and improve the wettability and fluidity of the epoxy resin system.

[0009] Preferably, it also includes:

[0010] The epoxy resin A is synthesized into phenolic epoxy resins with different relative molecular weights and functionalities according to the different thermoplastic linear phenolic resins.

[0011] Preferably, it also includes:

[0012] The thermoplastic linear phenolic resin includes at least one of a phenol formaldehyde type epoxy resin and an o-cresol formaldehyde type epoxy resin.

[0013] Preferably, it also includes:

[0014] The epoxy resin B is a compound containing two or more glycidyl ester groups in its structure.

[0015] Preferably, it also includes:

[0016] The epoxy resin B includes at least one of glycidyl phthalate, glycidyl tetrahydrophthalate and glycidyl hexahydrophthalate.

[0017] Preferably, it also includes:

[0018] The diluent includes at least one of butyl methacrylate and butyl acetate.

[0019] Preferably, it also includes:

[0020] The epoxy curing agent is a latent curing agent, which will initiate a curing reaction only after being heated to a certain temperature or pressure is applied to a certain degree.

[0021] Preferably, it also includes:

[0022] The latent curing agent includes at least one of imidazole derivatives, melamine and dicyandiamide.

[0023] In a second aspect, a method for preparing a low-viscosity, high-Tg prepreg epoxy resin system is provided, the preparation method comprising the following steps:

[0024] Step 1: Mix 10-20 parts of epoxy resin B and 6-10 parts of epoxy curing agent thoroughly;

[0025] Step 2: Grind the mixed solution in the first step using a three-roll mill and set aside after grinding;

[0026] Step 3: Heat 60-80 parts of epoxy resin A to 80-90°C, add 1-3 parts of diluent, mix well and then cool down;

[0027] Step 4: Add the solution obtained after grinding in the second step to the solution obtained in the third step at 60° C. and stir evenly to obtain an epoxy resin system.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The resin system can be solid at room temperature and does not stick to your hands;

[0030] 2. When the temperature of the resin system is 80°C, the viscosity of the resin system is below 2000cp and can be maintained for 2-4 hours;

[0031] 3. The glass transition temperature of the resin system can reach above 170°C, the curing temperature is 150°C, and the curing degree can reach 98% or above. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the method flow structure of the present invention.

[0033] Figure 2 It is a schematic diagram of the glass transition temperature experimental results of the present invention.

[0034] Figure 3 It is the viscosity-temperature curve test diagram of the present invention. DETAILED DESCRIPTION

[0035] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may think of other obvious variations.

[0036] A low-viscosity, high-Tg epoxy resin system for prepreg yarns, comprising the following raw materials in parts by weight:

[0037] Epoxy resin A: 60-80 parts, epoxy resin B: 20-40 parts, diluent: 1-3 parts, epoxy curing agent: 6-10 parts;

[0038] The epoxy resin A is prepared by polycondensation of a low molecular weight thermoplastic linear phenolic resin and epichlorohydrin under the action of an alkali;

[0039] The diluent is used to reduce the viscosity of the epoxy system and improve the wettability and fluidity of the epoxy resin system;

[0040] It should be noted that the epoxy resin A used in the present invention is usually a semi-solid with high viscosity at room temperature, and the softening point is ≤35, which ensures that the resin system can present the advantages of non-stickiness and high viscosity at room temperature, and the low softening point can ensure that the viscosity of the resin system is below 2000cp when the temperature is raised to 80°C.

[0041] Specifically, the epoxy resin A is synthesized into phenolic epoxy resins with different relative molecular weights and functionalities according to the different thermoplastic linear phenolic resins.

[0042] Specifically, the thermoplastic linear phenolic resin includes at least one of a phenol formaldehyde type epoxy resin and an o-cresol formaldehyde type epoxy resin.

[0043] Specifically, the epoxy resin B is a compound containing two or more glycidyl ester groups in its structure;

[0044] It should be noted that the epoxy resin B used in the present invention has the characteristic of good heat resistance, thereby ensuring that the glass transition temperature of the epoxy resin system reaches above 170° C. after curing, meeting the use requirements under special environments.

[0045] Specifically, the epoxy resin B includes at least one of glycidyl phthalate, glycidyl tetrahydrophthalate and glycidyl hexahydrophthalate.

[0046] Specifically, the diluent includes at least one of butyl methacrylate and butyl acetate.

[0047] Specifically, the epoxy curing agent is a latent curing agent, which will only initiate a curing reaction when heated to a certain temperature or pressure is applied to a certain degree;

[0048] It should be noted that the epoxy curing agent used in the present invention is a latent curing agent, and no curing and cross-linking reaction will occur at low temperatures, ensuring that the resin system can maintain a low viscosity range for a long time at 80°C, meeting the production requirements of prepreg yarns. After reaching the curing and cross-linking temperature, the curing degree of the cured product can be 98%, meeting the requirements for use in special environments.

[0049] Specifically, the latent curing agent includes at least one of imidazole derivatives, melamine and dicyandiamide.

[0050] like Figure 1 A method for preparing a low-viscosity, high-Tg prepreg yarn epoxy resin system is shown, and the preparation method comprises the following steps:

[0051] Step 1: Mix 10-20 parts of epoxy resin B and 6-10 parts of epoxy curing agent thoroughly;

[0052] Step 2: Grind the mixed solution in the first step using a three-roll mill and set aside after grinding;

[0053] Step 3: Heat 60-80 parts of epoxy resin A to 80-90°C, add 1-3 parts of diluent, mix well and then cool down;

[0054] Step 4: Add the solution obtained after grinding in the second step to the solution obtained in the third step at 60° C. and stir evenly to obtain an epoxy resin system.

[0055] Embodiment 1

[0056] Step 1: Add 20 parts of glycidyl phthalate and 6 parts of imidazole derivative into a reaction container and stir well;

[0057] Step 2: Grind the stirred solution using a three-roll grinder after taking it out and set aside for use;

[0058] Step 3: Add 60 parts of phenol formaldehyde epoxy resin into the reaction container, heat it to 80°C, then slowly add butyl methacrylate, stir evenly, and then reduce the temperature to below 60°C;

[0059] Step 4: Add the ground solution, stir evenly, quickly mix the resin system, cool to room temperature, and refrigerate for later use.

[0060] Embodiment 2

[0061] Step 1: Add 20 parts of glycidyl phthalate and 6 parts of imidazole derivative into a reaction container and stir well;

[0062] Step 2: Grind the stirred solution using a three-roll grinder after taking it out and set aside for use;

[0063] Step 3: Add 60 parts of phenol formaldehyde epoxy resin into the reaction container, heat it to 80°C, then slowly add butyl acetate, stir evenly, and then reduce the temperature to below 60°C;

[0064] Step 4: Add the ground solution, stir evenly, quickly pour out the mixed resin system, cool to room temperature, and refrigerate for later use.

[0065] Embodiment 3

[0066] Step 1: Add 20 parts of glycidyl phthalate and 6 parts of imidazole derivative into a reaction container and stir well;

[0067] Step 2: Grind the stirred solution using a three-roll grinder after taking it out and set aside for use;

[0068] Step 3, add 60 parts of o-cresol formaldehyde epoxy resin into the reaction container, heat it to 80°C, then slowly add butyl methacrylate, stir evenly, and then reduce the temperature to below 60°C;

[0069] Step 4: Add the ground solution, stir evenly, quickly mix the resin system, cool to room temperature, and refrigerate for later use.

[0070] The data of the above examples are statistically analyzed to obtain the following table data.

[0071] 24-09-28Bending strength test of resin system casting and mold

[0072] Table 1 24-09-28 Bending properties of resin system castings

[0073]

[0074] It can be seen from Table 1 that the bending strength of the 24-09-28 resin system matrix is ​​112.49 MPa, with a maximum of 124.72 MPa, and the performance is good.

[0075] 24-09-28 Impact toughness of resin system castings

[0076] Table 2 Impact toughness of 24-09-28 resin system castings

[0077]

[0078] From Table 2, we can see that the impact strength of the 24-09-28 resin system matrix is ​​19.3KJ / m 2 , the highest value reaches 21.191KJ / m 2 , good toughness.

[0079] like Figure 2 As shown, when the glass transition temperature experiment of the resin system matrix is ​​carried out, it can be concluded that the midpoint of the glass transition temperature is 177.8°C, and the glass transition temperature can reach above 170°C.

[0080] like Figure 3 As shown in the viscosity-temperature curve test diagram, the viscosity value at 80°C is 1800cp, so that at 80°C, the viscosity of the resin system is below 2000cp.

[0081] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention, and these changes and improvements fall within the scope of the present invention claimed.

Claims

1. A low viscosity high Tg epoxy resin system for prepreg yarn, characterized in that: The raw materials are as follows: Epoxy resin A: 60-80 parts, epoxy resin B: 20-40 parts, diluent: 1-3 parts, epoxy curing agent: 6-10 parts; The epoxy resin A is prepared by polycondensation of a low molecular weight thermoplastic linear phenolic resin and epichlorohydrin under the action of an alkali; The diluent is used to reduce the viscosity of the epoxy system and improve the wettability and fluidity of the epoxy resin system.

2. The low-viscosity, high-Tg epoxy resin system for prepreg yarn according to claim 1, characterized in that: Also includes: The epoxy resin A is synthesized into phenolic epoxy resins with different relative molecular weights and functionalities according to the different thermoplastic linear phenolic resins.

3. The low viscosity high Tg epoxy resin system for prepreg yarn according to claim 2, characterized in that: Also includes: The thermoplastic linear phenolic resin includes at least one of a phenol formaldehyde type epoxy resin and an o-cresol formaldehyde type epoxy resin.

4. The low-viscosity, high-Tg epoxy resin system for prepreg yarn according to claim 1, characterized in that: Also includes: The epoxy resin B is a compound containing two or more glycidyl ester groups in its structure.

5. The low-viscosity, high-Tg epoxy resin system for prepreg yarn according to claim 4, characterized in that: Also includes: The epoxy resin B includes at least one of glycidyl phthalate, glycidyl tetrahydrophthalate and glycidyl hexahydrophthalate.

6. The low-viscosity, high-Tg epoxy resin system for prepreg yarn according to claim 1, characterized in that: Also includes: The diluent includes at least one of butyl methacrylate and butyl acetate.

7. The low-viscosity, high-Tg epoxy resin system for prepreg yarn according to claim 1, characterized in that: Also includes: The epoxy curing agent is a latent curing agent, which will initiate a curing reaction only after being heated to a certain temperature or pressure is applied to a certain degree.

8. The low-viscosity, high-Tg epoxy resin system for prepreg yarn according to claim 7, characterized in that: Also includes: The latent curing agent includes at least one of imidazole derivatives, melamine and dicyandiamide.

9. A method for preparing a low-viscosity high-Tg prepreg epoxy resin system, used for preparing a low-viscosity high-Tg prepreg epoxy resin system according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: Step 1: Mix 10-20 parts of epoxy resin B and 6-10 parts of epoxy curing agent thoroughly; Step 2: Grind the mixed solution in the first step using a three-roll mill and set aside after grinding; Step 3: Heat 60-80 parts of epoxy resin A to 80-90°C, add 1-3 parts of diluent, mix well and then cool down; Step 4: Add the solution obtained after grinding in the second step to the solution obtained in the third step at 60° C. and stir evenly to obtain an epoxy resin system.

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