Fast curing epoxy resin prepreg and preparation method thereof

Abstract

The invention discloses a fast curing epoxy resin prepreg and a preparation method thereof. The formula comprises bio-based epoxy resin, a bio-based diluent, a curing agent and modified reinforced fibers, the preparation method comprises the following steps: step 1, weighing raw materials; 2, mixing the raw materials; step 3, vacuumizing and dipping; step 4, step-by-step curing; according to the invention, the infiltration speed of matrix resin is accelerated by adopting a method of combining reinforced fiber modification with vacuumizing impregnation, and the problem of low production efficiency caused by slow infiltration speed is solved; a cracking type photoinitiator, an auxiliary photoinitiator and an auxiliary curing agent are compounded to form a curing agent, so that the absorption range of ultraviolet rays is expanded, the initiation efficiency is improved, the internal curing condition of reinforced fibers is improved by adopting a step-by-step curing mode, and the problem that ultraviolet curing cannot be suitable for thicker prepreg is solved; environment-friendly and nontoxic bio-based epoxy resin, a bio-based diluent and a curing agent are adopted in the formula, and the concept of environmental protection is better met.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, in particular to a fast-curing epoxy resin prepreg and a preparation method thereof. Background Art

[0002] Epoxy resin prepreg is a composite material composed of epoxy resin, curing agent and fiber reinforcement material. It has the advantages of high specific modulus, high specific strength, fatigue resistance, corrosion resistance, etc., and is therefore widely used in aerospace, automobile manufacturing, sports equipment and other fields. However, the existing epoxy resin prepreg still has the following disadvantages: 1. The impregnation method is one of the main methods for preparing epoxy resin prepreg. Its principle is to infiltrate the fiber reinforcement material through the wettability of the matrix resin itself, and then obtain the prepreg through curing treatment. In this method, the speed at which the matrix resin impregnates the fiber reinforcement material depends on the affinity between the two. Therefore, for fiber reinforcement materials with poor affinity with the matrix resin, there is a problem of low production efficiency; 2. In the existing technology, in order to achieve rapid curing of epoxy resin prepreg, heating curing is generally adopted. By increasing the curing temperature, the curing temperature is increased. Faster movement speed of epoxy resin molecules and curing agent molecules increases the probability of effective collision between molecules, thereby accelerating the curing reaction. However, this method is not applicable to temperature-sensitive reinforcing materials such as plant fibers. Although ultraviolet curing can solve this problem, it is difficult to ensure complete internal curing for thicker epoxy resin prepregs; 3. Existing epoxy resin prepregs usually use epoxy resins based on bisphenol A as raw materials, aromatic amine curing agents, and organic solvents such as acetone as diluents. These raw materials pose a potential threat to the ecological environment and human health, and are therefore not in line with the concept of green environmental protection. Summary of the Invention

[0003] The object of the present invention is to provide a fast-curing epoxy resin prepreg and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a fast-curing epoxy resin prepreg, the formula of which includes: a bio-based epoxy resin, a bio-based diluent, a curing agent and a modified reinforcing fiber, wherein the mass percentage content of each component is: 50-70% bio-based epoxy resin, 7-14% bio-based diluent, 3-6% curing agent and 20-30% modified reinforcing fiber.

[0005] Preferably, the mass percentages of the components are: 60% of bio-based epoxy resin, 10% of bio-based diluent, 5% of curing agent and 25% of modified reinforcing fiber.

[0006] Preferably, the bio-based epoxy resin is one or more combinations of glycerol-based epoxy resin, cardanol-based epoxy resin, plant oil-based epoxy resin, furan compound-based epoxy resin, and lignin derivative-based epoxy resin.

[0007] Preferably, the bio-based diluent is one or more combinations of palm oil glycidyl ether, castor oil glycidyl ether, polyglycerol glycidyl ether, dimer acid glycidyl ether, isosorbide glycidyl ether, and sorbitol glycidyl ether.

[0008] Preferably, the curing agent includes: a cleavage photoinitiator, an auxiliary photoinitiator and a co-curing agent, and the mass percentage content of each component is: 50-70% of the cleavage photoinitiator, 25-35% of the auxiliary photoinitiator and 7-14% of the co-curing agent, preferably 60% of the cleavage photoinitiator, 30% of the auxiliary photoinitiator and 10% of the co-curing agent.

[0009] Preferably, the cleavage-type photoinitiator is one or more combinations of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 1-hydroxy-cyclohexylphenyl ketone.

[0010] Preferably, the auxiliary photoinitiator is one or more combinations of isopropyl thioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-1-propanone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0011] Preferably, the auxiliary curing agent is one or more combinations of pentaerythritol tetrakis (3-mercaptopropionate), trimethylolpropane tris (3-mercaptopropionate), and ethylene glycol dimercaptoacetate.

[0012] A method for preparing a fast-curing epoxy resin prepreg, comprising the steps of weighing raw materials, mixing the raw materials, vacuum impregnation, and curing in steps.

[0013] In the above step 1, the bio-based epoxy resin, bio-based diluent, curing agent and modified reinforcing fiber are weighed according to the formula ratio, with the sum of the mass percentages of each component being 1;

[0014] In the above step 2, the bio-based epoxy resin and the bio-based diluent are added to the reactor, stirred at a stirring speed of 150-300 r / min at 40-60° C. for 10-30 minutes, and fully mixed to obtain a resin system, and the curing agent is added to the resin system, and stirred at a stirring speed of 100-150 r / min at 40-60° C. for 10-15 minutes to obtain a mixture;

[0015] In the above step 3, the modified reinforcing fiber is placed in a mold, and then the mixture prepared in step 2 is poured into the mold, and the mold is placed in a vacuum impregnation equipment, vacuumed to 0.08-0.09 MPa, and maintained for 10-15 minutes;

[0016] In the above step 4, the modified reinforcing fiber impregnated in step 3 is placed under an ultraviolet irradiation device with an ultraviolet intensity of 50-100 mW / cm 2 , irradiation time is 5-10min, then increase the UV intensity to 150-300mW / cm 2 , continue irradiation for 15-20 minutes to complete curing and obtain prepreg.

[0017] Preferably, in step 1, the preparation method of the modified reinforcing fiber is specifically as follows: soaking the reinforcing fiber in a solution containing a silane coupling agent, wherein the concentration of the coupling agent solution is 2%-5%, and the soaking time is 40-60 minutes, and then drying the reinforcing fiber at 70-100°C for 1-2 hours to obtain the modified reinforcing fiber.

[0018] Compared with the prior art, the present invention has the following beneficial effects: the present invention adopts the method of reinforcing fiber modification combined with vacuum impregnation to accelerate the infiltration speed of the matrix resin, thereby solving the problem of low production efficiency caused by slow infiltration speed; a pyrolysis-type photoinitiator, an auxiliary photoinitiator and an auxiliary curing agent are used to compound the curing agent, thereby expanding the absorption range of ultraviolet rays and improving the initiation efficiency; a step-by-step curing method is used to improve the internal curing of the reinforcing fiber, thereby solving the problem that ultraviolet curing cannot be applied to thicker prepregs; the formula adopts environmentally friendly and non-toxic bio-based epoxy resin, bio-based diluent and curing agent, which is more in line with the concept of green environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] Please see the attached Figure 1 , a technical solution provided by the present invention:

[0022] Example 1:

[0023] A fast-curing epoxy resin prepreg comprises a formula comprising: a bio-based epoxy resin, a bio-based diluent, a curing agent and a modified reinforcing fiber, wherein the mass percentages of the components are: 60% of the bio-based epoxy resin, 10% of the bio-based diluent, 5% of the curing agent and 25% of the modified reinforcing fiber, wherein the bio-based epoxy resin is a glyceryl epoxy resin, and the bio-based diluent is palm oil-based glycidyl ether, and the curing agent comprises: a cleavage-type photoinitiator, an auxiliary photoinitiator and a co-curing agent, wherein the mass percentages of the components are: 60% of the cleavage-type photoinitiator, 30% of the auxiliary photoinitiator and 10% of the co-curing agent, wherein the cleavage-type photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, the auxiliary photoinitiator is isopropyl thioxanthone, and the co-curing agent is pentaerythritol tetrakis(3-mercaptopropionate).

[0024] A method for preparing a fast-curing epoxy resin prepreg, comprising the steps of weighing raw materials, mixing the raw materials, vacuum impregnation, and curing in steps.

[0025] In the above step 1, the bio-based epoxy resin, bio-based diluent, curing agent and modified reinforcing fiber are weighed according to the formula ratio, with the sum of the mass percentages of each component being 1; wherein the preparation method of the modified reinforcing fiber is specifically: soaking the reinforcing fiber in a solution containing a silane coupling agent, wherein the concentration of the coupling agent solution is 2%-5%, and the soaking time is 40-60 minutes, and then drying the reinforcing fiber at 70-100° C. for 1-2 hours to obtain the modified reinforcing fiber;

[0026] In the above step 2, the bio-based epoxy resin and the bio-based diluent are added to the reactor, stirred at a stirring speed of 150-300 r / min at 40-60° C. for 10-30 minutes, and fully mixed to obtain a resin system, and the curing agent is added to the resin system, and stirred at a stirring speed of 100-150 r / min at 40-60° C. for 10-15 minutes to obtain a mixture;

[0027] In the above step 3, the modified reinforcing fiber is placed in a mold, and then the mixture prepared in step 2 is poured into the mold, and the mold is placed in a vacuum impregnation equipment, vacuumed to 0.08-0.09 MPa, and maintained for 10-15 minutes;

[0028] In the above step 4, the modified reinforcing fiber impregnated in step 3 is placed under an ultraviolet irradiation device with an ultraviolet intensity of 50-100 mW / cm 2 , irradiation time is 5-10min, then increase the UV intensity to 150-300mW / cm 2 , continue irradiation for 15-20 minutes to complete curing and obtain prepreg.

[0029] Example 2:

[0030] Referring to the formula and method of Example 1, only the bio-based epoxy resin was changed to cardanol-based epoxy resin, and the bio-based diluent was changed to castor oil glycidyl ether.

[0031] Example 3:

[0032] Referring to the formulation and method of Example 1, only the cleavage-type photoinitiator was changed to 2-hydroxy-2-methyl-1-phenyl-1-propanone, the auxiliary photoinitiator was changed to 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-1-propanone, and the co-curing agent was changed to trimethylolpropane tris(3-mercaptopropionate).

[0033] Example 4:

[0034] Referring to the formula and method of Example 1, only the mass percentage content of each component in the formula was changed to: 70% bio-based epoxy resin, 7% bio-based diluent, 3% curing agent and 20% modified reinforcing fiber.

[0035] Example 5:

[0036] Referring to the formula and method of Example 1, only the mass percentage content of each component in the formula was changed to: 50% bio-based epoxy resin, 14% bio-based diluent, 6% curing agent and 30% modified reinforcing fiber.

[0037] Comparative Example 1:

[0038] Referring to the formula and method of Example 1, only the vacuum impregnation in the method was changed to normal pressure impregnation, and the reinforcing fibers were not modified.

[0039] Comparative Example 2:

[0040] Referring to the formula and method of Example 1, only the curing agent in the formula was changed to 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone.

[0041] The properties of each embodiment and comparative example are compared in the following table:

[0042]

[0043] Based on the above, the advantages of the present invention are: the present invention modifies the reinforcing fiber to enhance its affinity with the matrix resin, and at the same time, by adopting a vacuum impregnation method, effectively accelerates the infiltration speed of the matrix resin, thereby improving production efficiency; the curing agent used in the formula is compounded by different types of cleavage-type photoinitiators, auxiliary photoinitiators and co-curing agents, which can expand the absorption range of ultraviolet rays and improve the initiation efficiency, and by adopting a step-by-step curing method, effectively improves the internal curing of the reinforcing fiber, so that it can be suitable for the curing of thicker prepregs; the bio-based epoxy resin, bio-based diluent and curing agent used in the formula of the present invention are all low-toxic and non-toxic substances, and therefore will not threaten human health, and are more in line with the concept of green environmental protection.

[0044] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A fast-curing epoxy resin prepreg, the formula comprising: The bio-based epoxy resin, bio-based diluent, curing agent and modified reinforcing fiber are characterized in that the mass percentage content of each component is: 50-70% bio-based epoxy resin, 7-14% bio-based diluent, 3-6% curing agent and 20-30% modified reinforcing fiber.

2. The fast-curing epoxy resin prepreg according to claim 1, characterized in that: The mass percentage contents of the components are: 60% of bio-based epoxy resin, 10% of bio-based diluent, 5% of curing agent and 25% of modified reinforcing fiber.

3. The fast-curing epoxy resin prepreg according to claim 2, wherein: The bio-based epoxy resin is one or more combinations of glycerol-based epoxy resin, cardanol-based epoxy resin, plant oil-based epoxy resin, furan compound-based epoxy resin, and lignin derivative-based epoxy resin.

4. The fast-curing epoxy resin prepreg according to claim 2, wherein: The bio-based diluent is one or more combinations of palm oil glycidyl ether, castor oil glycidyl ether, polyglycerol glycidyl ether, dimer acid glycidyl ether, isosorbide glycidyl ether, and sorbitol glycidyl ether.

5. The fast-curing epoxy resin prepreg according to claim 2, characterized in that: The curing agent includes: a cleavage photoinitiator, an auxiliary photoinitiator and a co-curing agent, and the mass percentage content of each component is: 50-70% of the cleavage photoinitiator, 25-35% of the auxiliary photoinitiator and 7-14% of the co-curing agent, preferably 60% of the cleavage photoinitiator, 30% of the auxiliary photoinitiator and 10% of the co-curing agent.

6. The fast-curing epoxy resin prepreg according to claim 5, characterized in that: The cleavage-type photoinitiator is one or more combinations of 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylpropiophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 1-hydroxy-cyclohexylphenyl ketone.

7. The fast-curing epoxy resin prepreg according to claim 5, characterized in that: The auxiliary photoinitiator is one or more combinations of isopropyl thioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-1-propanone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

8. The fast-curing epoxy resin prepreg according to claim 5, characterized in that: The auxiliary curing agent is one or more combinations of pentaerythritol tetrakis (3-mercaptopropionate), trimethylolpropane tris (3-mercaptopropionate), and ethylene glycol dimercaptoacetate.

9. A method for preparing a fast-curing epoxy resin prepreg, comprising the steps of: weighing raw materials; mixing the raw materials; vacuum impregnation; and curing in steps; wherein: In the above step 1, the bio-based epoxy resin, bio-based diluent, curing agent and modified reinforcing fiber are weighed according to the formula ratio, with the sum of the mass percentages of each component being 1; In the above step 2, the bio-based epoxy resin and the bio-based diluent are added to the reactor, stirred at a stirring speed of 150-300 r / min at 40-60° C. for 10-30 minutes, and fully mixed to obtain a resin system, and the curing agent is added to the resin system, and stirred at a stirring speed of 100-150 r / min at 40-60° C. for 10-15 minutes to obtain a mixture; In the above step 3, the modified reinforcing fiber is placed in a mold, and then the mixture prepared in step 2 is poured into the mold, and the mold is placed in a vacuum impregnation equipment, vacuumed to 0.08-0.09 MPa, and maintained for 10-15 minutes; In the above step 4, the modified reinforcing fiber impregnated in step 3 is placed under an ultraviolet irradiation device with an ultraviolet intensity of 50-100 mW / cm 2 , irradiation time is 5-10min, then increase the UV intensity to 150-300mW / cm 2 , continue irradiation for 15-20 minutes to complete curing and obtain prepreg.

10. The method for preparing a fast-curing epoxy resin prepreg according to claim 9, wherein: In step 1, the preparation method of the modified reinforcing fiber is specifically as follows: the reinforcing fiber is immersed in a solution containing a silane coupling agent, the concentration of the coupling agent solution is 2%-5%, and the immersion time is 40-60 minutes, and then the reinforcing fiber is dried at 70-100°C for 1-2 hours to obtain the modified reinforcing fiber.

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