Epoxy resin composition and preparation method thereof, and epoxy resin prepreg and preparation method thereof

Abstract

The invention relates to an epoxy resin composition and a preparation method thereof, and an epoxy resin prepreg and a preparation method thereof. Comprising the following steps: mixing epoxy resin, 2, 4-diphenylmethane diisocyanate and 4, 4-diphenylmethane diisocyanate, and synthesizing under the action of a catalyst to obtain a transparent toughening agent; mixing the mixed epoxy resin and the transparent toughening agent to obtain a first mixed solution; adding a defoaming agent, an ultraviolet light absorber, an antioxidant, a light stabilizer and a fluorescent agent to obtain a second mixed solution; cooling the second mixed solution to 60-70 DEG C, adding a curing agent and an accelerant, preserving heat, vacuumizing, defoaming and mixing for 0.3-0.4 hour to obtain an epoxy resin composition; the invention provides an epoxy resin composition and a preparation method thereof as well as an epoxy resin prepreg and a preparation method thereof. The preparation method of the epoxy resin composition is used for solving the technical problem of no research on heat resistance, high transparency, yellowing resistance and high toughness of an epoxy resin material at present.

Description

Technical Field

[0001] The invention relates to the field of epoxy resin preparation, in particular to an epoxy resin composition and a preparation method thereof, an epoxy resin prepreg and a preparation method thereof. Background Art

[0002] Due to the advantages of high strength, high modulus, and high temperature resistance of carbon fiber, carbon fiber composite materials have been widely used in aerospace, military equipment and other fields. With the continuous maturity of domestic carbon fiber preparation technology, carbon fiber composite materials are also widely used in the civilian consumer market, such as drones, automobiles, bicycles, and golf clubs. Carbon fiber composite materials are often based on epoxy resin, because epoxy resin has good mechanical strength, storage stability and operation processability, but the brittleness of the cured product obtained by using epoxy resin alone and the yellowing under ultraviolet radiation seriously affect the service life and appearance of the product, and it is always difficult to better meet the people's increasing consumption level needs.

[0003] The brittleness of epoxy resin cured products is often improved by toughening. Commonly used transparent toughening agents include inorganic fillers, rubber, thermoplastic resins, etc. However, the addition of these transparent toughening agents will directly change the transparency of the resin matrix and affect the appearance of the composite material. The addition of rubber and thermoplastic resins will also reduce the heat resistance of the material. The yellowing of epoxy resin is mainly due to the fact that the bisphenol A structure in the resin is easily oxidized to form hydroxyl groups under the action of light and heat. As an intermediate of carbon fiber reinforced epoxy resin composite materials, the performance of carbon fiber reinforced epoxy resin prepreg directly affects the final performance of the composite product. Therefore, the development of a carbon fiber prepreg with heat resistance, high transparency, yellowing resistance and high toughness is crucial to improving the application effect of carbon fiber composite materials.

[0004] CN113831689A discloses a colorless, transparent, UV-resistant prepreg epoxy resin composition and a preparation method thereof, which effectively improves the transparency, UV resistance and yellowing resistance of the epoxy resin, but does not take into account the study of the toughness improvement scheme. CN104945856A discloses a preparation method of a highly transparent, yellowing-resistant epoxy resin composite material, which studies transparency and yellowing resistance, but does not take into account the study of toughness improvement. CN114230974B discloses a heat-increasing epoxy resin for carbon fiber epoxy prepreg and a preparation method thereof, and the epoxy resin prepared by the method takes into account excellent heat resistance and toughness, but there is no corresponding report on taking into account transparency and yellowing resistance.

[0005] Therefore, in view of the above problems, the present invention urgently needs to provide an epoxy resin composition and a preparation method thereof, an epoxy resin prepreg and a preparation method thereof. Summary of the invention

[0006] The object of the present invention is to provide an epoxy resin composition and a preparation method thereof, an epoxy resin prepreg and a preparation method thereof, and to solve the technical problem in the prior art that there is currently no research on epoxy resin materials that are heat-resistant, highly transparent, resistant to yellowing and high toughness through the preparation method of the epoxy resin composition.

[0007] The present invention provides a method for preparing an epoxy resin composition, comprising the following steps: The epoxy resin, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate are mixed and synthesized under the action of a catalyst to obtain a transparent toughening agent; Mix the mixed epoxy resin and the transparent toughening agent, and perform vacuum degassing and mixing at 120-130° C. for 1-3 hours to obtain a first mixed solution; The first mixed solution is cooled to 70-85° C., a defoamer, an ultraviolet absorber, an antioxidant, a light stabilizer and a fluorescent agent are added, and the mixture is kept warm, vacuumed, degassed and mixed for 1-1.5 hours to obtain a second mixed solution; The second mixed liquid is cooled to 60-70° C., a curing agent and an accelerator are added, the mixture is kept warm, vacuumed, degassed and mixed for 0.3-0.4 h, and the mixture is unloaded while hot to obtain an epoxy resin composition.

[0008] Preferably, the mixed epoxy resin comprises, by weight, 50-60 parts of bisphenol A liquid epoxy resin, 5-10 parts of novolac epoxy resin, 5-10 parts of alicyclic epoxy resin and 20-40 parts of bisphenol A solid epoxy resin.

[0009] Preferably, the mass ratio of epoxy resin, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate is 3:(1-10):1; the catalyst is one of an organic metal catalyst, an inorganic metal salt catalyst or an imidazole catalyst.

[0010] Preferably, the accelerator is an imidazole accelerator terminated with an inert group; the accelerator preparation process comprises: Mix 2-ethyl-4-methylimidazole and an organic acid aqueous solution in a mass ratio of 100:(50-200), heat to 100-120°C, reflux, stir and keep warm for 1-1.5h, cool to 60-85°C, transfer to an oven and bake until constant weight is obtained to obtain an accelerator; Wherein, in the organic acid aqueous solution, the mass ratio of organic acid to water is 1:(5-12); The organic acid includes one of acetic acid, lactic acid, cyanuric acid, salicylic acid or acrylic acid.

[0011] Preferably, the mass ratio of the mixed epoxy resin and the transparent toughening agent is 100:(5-30); The mass ratio of mixed epoxy resin to defoamer is 100:(0.1-3.0); The mass ratio of the mixed epoxy resin to the ultraviolet absorber is 100:(0.1-5); The mass ratio of the mixed epoxy resin to the antioxidant is 100:(0.1-5); The mass ratio of mixed epoxy resin to light stabilizer is 100:(0.1-1.0); The mass ratio of mixed epoxy resin to fluorescent agent is 100:(0.01-1.0); The mass ratio of mixed epoxy resin to curing agent is 100:(2-10); The mass ratio of mixed epoxy resin to accelerator is 100:(2-10).

[0012] Preferably, the bisphenol A type liquid epoxy resin is at least one of epoxy resin 128 or epoxy resin 127; The bisphenol A type solid epoxy resin is one or a mixture of epoxy resin E20, epoxy resin E14, epoxy resin E901 or epoxy resin E909; The novolac epoxy resin is one or a mixture of novolac epoxy resin F51, novolac epoxy resin F44 or novolac epoxy resin F48; The alicyclic epoxy resin is one of alicyclic epoxy resin AG-80, alicyclic epoxy resin 2021P, alicyclic epoxy resin CY179, alicyclic epoxy resin CY184, alicyclic epoxy resin CY183, and alicyclic epoxy resin ERL4221, or a mixture of several of them.

[0013] Preferably, the ultraviolet absorber is a mixture of one or more of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-octoxyphenol, phenyl o-hydroxybenzoate, 2-hydroxy-4-n-octoxybenzophenone, and 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole; The antioxidant is one of amine antioxidants, hindered phenol antioxidants or phosphite-based high-efficiency antioxidants; The light stabilizer is a mixture of one or more of hexamethylphosphoric triamide, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, mono(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate or 1-methyl-8-(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate; The fluorescent whitening agent is a mixture of one or more of a stilbene fluorescent whitening agent, a pyrazoline fluorescent whitening agent or a benzoxazine fluorescent whitening agent; The defoaming agent is an organosilicon defoaming agent or a polymer defoaming agent; The curing agent is dicyandiamide or 4,4'-diaminodiphenyl sulfone; The diphenylethylene fluorescent brightener is fluorescent brightener OB-1 or fluorescent brightener FP-127; The pyrazoline fluorescent brightener is a 2-pyrazoline fluorescent brightener; The benzoxazine fluorescent whitening agent is at least one of a BBOT benzoxazine fluorescent whitening agent or a KCB benzoxazine fluorescent whitening agent.

[0014] The present invention also provides an epoxy resin composition obtained based on the epoxy resin composition preparation method as described in any one of the above.

[0015] The present invention also provides an epoxy resin prepreg, comprising a reinforcing material and the epoxy resin composition as described above, wherein the mass percentage of the epoxy resin composition in the epoxy resin prepreg is 55-70%.

[0016] The present invention also provides a method for preparing an epoxy resin prepreg, comprising the following steps: The epoxy resin composition as described above is prepared into a film; The adhesive film and the reinforcing material are hot-pressed to obtain epoxy resin prepreg.

[0017] The epoxy resin composition and preparation method thereof, epoxy resin prepreg and preparation method thereof provided by the present invention have the following improvements compared with the prior art: 1. The method for preparing an epoxy resin composition provided by the present invention comprises introducing a transparent toughening agent prepared by mixing epoxy resin, 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate in a set ratio under catalytic conditions into an epoxy resin system, thereby improving the toughness of the epoxy resin matrix cured product while ensuring that the material has excellent transparency. At the same time, a mixed epoxy resin is used, a mixed epoxy resin of bisphenol A liquid epoxy resin, bisphenol A solid epoxy resin, phenolic epoxy resin and alicyclic epoxy resin. Bisphenol A liquid epoxy resin and bisphenol A solid epoxy resin are mixed to adjust the viscosity-temperature fluidity of the resin matrix. While ensuring that the resin matrix is ​​fully impregnated with the carbon fiber, "zero glue absorption" curing is achieved. The phenolic epoxy resin has a unique rigid benzene ring structure, and the alicyclic epoxy resin is cured with a curing agent. The strong three-dimensional network structure produced provides the material with good heat resistance. The glass transition temperature (Tg) of the epoxy resin composition cured product is ≥120°C, so that the high-toughness epoxy resin material has both high transparency and anti-yellowing and toughening characteristics, which is effective in improving the service life of the composite material.

[0018] 2. The preparation method of the epoxy resin composition provided by the present invention, the addition of ultraviolet absorber, antioxidant, light stabilizer and fluorescent agent can help the epoxy resin matrix resist the damage of its chain segments by the air oxygen environment and ultraviolet light, and play a role in yellowing resistance. The curing agent can realize the cross-linking and curing of the resin matrix. The homemade accelerator is capped with inert groups and has latency, which can reduce the curing temperature of the resin matrix and make the prepreg have a longer storage life. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The present invention provides a method for preparing an epoxy resin composition, comprising the following steps: The epoxy resin, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate are mixed and synthesized under the action of a catalyst to obtain a transparent toughening agent; Mix the mixed epoxy resin and the transparent toughening agent, and perform vacuum degassing and mixing at 120-130° C. for 1-3 hours to obtain a first mixed solution; The first mixed solution is cooled to 70-85° C., a defoamer, an ultraviolet absorber, an antioxidant, a light stabilizer and a fluorescent agent are added, and the mixture is kept warm, vacuumed, degassed and mixed for 1-1.5 hours to obtain a second mixed solution; The second mixed liquid is cooled to 60-70° C., a curing agent and an accelerator are added, the mixture is kept warm, vacuumed, degassed and mixed for 0.3-0.4 h, and the mixture is unloaded while hot to obtain an epoxy resin composition.

[0021] Preferably, the mixed epoxy resin comprises, by weight, 50-60 parts of bisphenol A liquid epoxy resin, 5-10 parts of novolac epoxy resin, 5-10 parts of alicyclic epoxy resin and 20-40 parts of bisphenol A solid epoxy resin.

[0022] Preferably, the mass ratio of epoxy resin, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate is 3:(1-10):1; the catalyst is one of an organic metal catalyst, an inorganic metal salt catalyst or an imidazole catalyst.

[0023] Preferably, the accelerator is an imidazole accelerator terminated with an inert group; the accelerator preparation process comprises: Mix 2-ethyl-4-methylimidazole and an organic acid aqueous solution in a mass ratio of 100:(50-200), heat to 100-120°C, reflux, stir and keep warm for 1-1.5h, cool to 60-85°C, transfer to an oven and bake until constant weight is obtained to obtain an accelerator; Wherein, in the organic acid aqueous solution, the mass ratio of organic acid to water is 1:(5-12); The organic acid includes one of acetic acid, lactic acid, cyanuric acid, salicylic acid or acrylic acid.

[0024] Preferably, the mass ratio of the mixed epoxy resin and the transparent toughening agent is 100:(5-30); The mass ratio of mixed epoxy resin to defoamer is 100:(0.1-3.0); The mass ratio of the mixed epoxy resin to the ultraviolet absorber is 100:(0.1-5); The mass ratio of the mixed epoxy resin to the antioxidant is 100:(0.1-5); The mass ratio of mixed epoxy resin to light stabilizer is 100:(0.1-1.0); The mass ratio of mixed epoxy resin to fluorescent agent is 100:(0.01-1.0); The mass ratio of mixed epoxy resin to curing agent is 100:(2-10); The mass ratio of mixed epoxy resin to accelerator is 100:(2-10); Preferably, The bisphenol A type liquid epoxy resin is at least one of epoxy resin 128 and epoxy resin 127; The bisphenol A type solid epoxy resin is one or a mixture of epoxy resin E20, epoxy resin E14, epoxy resin E901 or epoxy resin E909; The novolac epoxy resin is one or a mixture of novolac epoxy resin F51, novolac epoxy resin F44 or novolac epoxy resin F48; The alicyclic epoxy resin is one of alicyclic epoxy resin AG-80, alicyclic epoxy resin 2021P, alicyclic epoxy resin CY179, alicyclic epoxy resin CY184, alicyclic epoxy resin CY183, and alicyclic epoxy resin ERL4221, or a mixture of several of them.

[0025] Preferably, the ultraviolet absorber is a mixture of one or more of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-octoxyphenol, phenyl o-hydroxybenzoate, 2-hydroxy-4-n-octoxybenzophenone, and 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole; The antioxidant is one of amine antioxidants, hindered phenol antioxidants or phosphite-based high-efficiency antioxidants; The light stabilizer is a mixture of one or more of hexamethylphosphoric triamide, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, mono(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate or 1-methyl-8-(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate; The fluorescent whitening agent is a mixture of one or more of a stilbene fluorescent whitening agent, a pyrazoline fluorescent whitening agent or a benzoxazine fluorescent whitening agent; The defoaming agent is an organosilicon defoaming agent or a polymer defoaming agent; The curing agent is dicyandiamide or 4,4'-diaminodiphenyl sulfone; The diphenylethylene fluorescent brightener is fluorescent brightener OB-1 or fluorescent brightener FP-127; The pyrazoline fluorescent brightener is a 2-pyrazoline fluorescent brightener; The benzoxazine fluorescent whitening agent is at least one of a BBOT benzoxazine fluorescent whitening agent or a KCB benzoxazine fluorescent whitening agent; The present invention also provides an epoxy resin composition obtained based on the epoxy resin composition preparation method as described in any one of the above.

[0026] The present invention also provides an epoxy resin prepreg, comprising a reinforcing material and the epoxy resin composition as described above, wherein the mass percentage of the epoxy resin composition in the epoxy resin prepreg is 55-70%.

[0027] The present invention also provides a method for preparing an epoxy resin prepreg, comprising the following steps: The epoxy resin composition as described above is prepared into a film; The adhesive film and the reinforcing material are hot-pressed to obtain epoxy resin prepreg.

[0028] The epoxy resin composition and preparation method thereof provided by the present invention are characterized in that a transparent toughening agent prepared by mixing epoxy resin, 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate in a certain proportion under catalytic conditions is introduced into the epoxy resin system, thereby improving the toughness of the epoxy resin matrix cured product while ensuring that the material has excellent transparency.

[0029] The transparent toughening agent provided by the present invention can improve the toughness of the resin matrix while ensuring that the resin matrix cured product has excellent transparency, because 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate are polymerized under a catalyst to generate polyisocyanate with sufficient molecular weight, and the polyisocyanate is then reacted with the epoxy resin to form a polyisocyanate structure blocked or segmented with the epoxy resin. The polyisocyanate itself has good transparency, and after being cross-linked with the epoxy resin, it can be better cross-linked with the epoxy resin composition to form a homogeneous copolymer, thereby ensuring the transparency of the resin matrix. The long-chain structure of the polyisocyanate can provide good flexibility for the homogeneous copolymer, so that the material has more excellent toughness, prevents the occurrence of brittle fracture of the material, and ensures that the material has better performance and longer service life.

[0030] The addition of the ultraviolet absorber, antioxidant, light stabilizer and fluorescent agent of the present invention can help the epoxy resin matrix resist the damage of the air oxygen environment and ultraviolet light to its chain segments, and play a role in yellowing resistance. The curing agent can realize the cross-linking and curing of the resin matrix. The homemade accelerator is capped with inert groups and has latency, which can reduce the curing temperature of the resin matrix and make the prepreg have a longer storage life.

[0031] The present invention adopts a mixed epoxy resin, and adopts a mixed epoxy resin of bisphenol A type liquid epoxy resin, bisphenol A type solid epoxy resin, phenolic epoxy resin and alicyclic epoxy resin. The bisphenol A type liquid epoxy resin and the bisphenol A type solid epoxy resin are mixed to adjust the viscosity-temperature fluidity of the resin matrix, and "zero glue absorption" curing is achieved while ensuring that the resin matrix fully impregnates the carbon fiber. The phenolic epoxy resin has a unique benzene ring rigid structure, and the alicyclic epoxy resin is cured with a curing agent. The strong three-dimensional network structure produced provides good heat resistance for the material. The glass transition temperature (Tg) of the epoxy resin composition cured product is ≥120°C, so that the epoxy resin material with high toughness has both high transparency and anti-yellowing and toughening dual characteristics, and has a significant effect on improving the service life of the composite material.

[0032] Embodiment 1 The epoxy resin composition provided in this embodiment has a specific preparation method comprising: 101) epoxy resin, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate are mixed in a mass ratio of 3:5:1, and synthesized under the action of an organic metal catalyst to obtain a transparent toughening agent; 102) 100 parts of mixed epoxy resin and 15 parts of transparent toughening agent are mixed, and vacuum degassing and mixing are performed at 120° C. for 2.5 hours to obtain a first mixed solution; 103) Cool the first mixed solution to 80°C, add 0.3 parts of defoaming agent, 0.5 parts of ultraviolet absorber, 0.5 parts of antioxidant, 0.4 parts of light stabilizer and 0.025 parts of fluorescent agent, keep the mixture warm and vacuum degas for 1 hour to obtain a second mixed solution; 104) The second mixed liquid is cooled to 65°C, 4.5 parts of curing agent and 2 parts of accelerator are added, the mixture is kept warm and vacuumed for degassing for 0.3 hours, and the mixture is unloaded while hot to obtain an epoxy resin composition.

[0033] The mixed epoxy resin includes, by weight, 60 parts of bisphenol A liquid epoxy resin, 5 parts of novolac epoxy resin, 5 parts of alicyclic epoxy resin and 30 parts of bisphenol A solid epoxy resin; Among them, the bisphenol A type liquid epoxy resin is epoxy resin 128; the bisphenol A type solid epoxy resin is epoxy resin E901; the novolac epoxy resin is novolac epoxy resin F51; The alicyclic epoxy resin is alicyclic epoxy resin AG-80; The accelerator is an imidazole accelerator terminated with an inert group; The accelerator preparation process includes: 2-ethyl-4-methylimidazole and an organic acid aqueous solution were mixed in a mass ratio of 100:200, heated to 100°C, refluxed, stirred and kept warm for 1 hour, cooled to 60°C, transferred to an oven and baked until completely constant weight, to obtain an accelerator; The ultraviolet absorber is 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-octoxyphenol; The antioxidant is antioxidant 1010; The light stabilizer is hexamethylphosphoric triamide; The fluorescent brightener is fluorescent brightener OB-1; The defoamer is defoamer BYK-A530; The curing agent is dicyandiamide.

[0034] This embodiment also provides a method for preparing an epoxy resin prepreg, comprising the following steps: 105) preparing the obtained epoxy resin composition into an adhesive film, wherein the coating temperature of the epoxy resin composition when coating the adhesive film is 75° C. and the adhesive content is 30%; 106) The adhesive film and the reinforcing material are hot-pressed to obtain an epoxy resin prepreg, wherein the pressing temperature when the adhesive film and the reinforcing material are hot-pressed is 70° C., and the mass percentage of the epoxy resin composition in the epoxy resin prepreg is 55%.

[0035] The epoxy resin composition was poured into a sample mold, cured at 80°C for 30 min, and cured at 120°C for 60 min to obtain a test piece. The properties of the test piece are shown in Table 1.

[0036] Embodiment 2 The epoxy resin composition provided in this embodiment has a specific preparation method comprising: 201) epoxy resin, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate are mixed in a mass ratio of 3:10:1, and synthesized under the action of an inorganic metal catalyst to obtain a transparent toughening agent; 202) 100 parts of mixed epoxy resin and 10 parts of transparent toughening agent are mixed, and vacuum degassing and mixing are performed at 120° C. for 3 hours to obtain a first mixed solution; 203) Cooling the first mixed solution to 70°C, adding 1.0 part of defoaming agent, 1.0 part of ultraviolet absorber, 1.0 part of antioxidant, 1.0 part of light stabilizer and 1.0 part of fluorescent agent, keeping the mixture warm and vacuuming for degassing for 1.5 hours to obtain a second mixed solution; 204) The second mixed liquid is cooled to 70°C, 6 parts of curing agent and 5 parts of accelerator are added, the mixture is kept warm and vacuumed for degassing for 0.4 hours, and the mixture is unloaded while hot to obtain an epoxy resin composition.

[0037] Wherein, the mixed epoxy resin includes, by weight, 55 parts of bisphenol A type liquid epoxy resin, 55 parts of novolac epoxy resin, 510 parts of alicyclic epoxy resin and 30 parts of bisphenol A solid epoxy resin; The bisphenol A type liquid epoxy resin is epoxy resin 128; The bisphenol A type solid epoxy resin is epoxy resin E901; The novolac epoxy resin is novolac epoxy resin F51; The alicyclic epoxy resin is alicyclic epoxy resin AG-80; The accelerator is an imidazole accelerator terminated with an inert group; The accelerator is prepared in the same manner as in Example 1; The ultraviolet absorber is 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-octoxyphenol; The antioxidant is antioxidant 1010; The light stabilizer is hexamethylphosphoric triamide; The fluorescent brightener is fluorescent brightener OB-1; The defoamer is defoamer BYK-A530; The curing agent is dicyandiamide.

[0038] This embodiment also provides a method for preparing an epoxy resin prepreg, comprising the following steps: 205) preparing the obtained epoxy resin composition into an adhesive film, wherein the coating temperature of the epoxy resin composition when coating the adhesive film is 75° C. and the adhesive content is 45%; 206) The adhesive film and the reinforcing material are hot-pressed to obtain an epoxy resin prepreg, wherein the pressing temperature when the adhesive film and the reinforcing material are hot-pressed is 70° C., and the mass percentage of the epoxy resin composition in the epoxy resin prepreg is 55%.

[0039] The epoxy resin composition was poured into a sample mold, cured at 80°C for 30 min, and cured at 120°C for 60 min to obtain a test piece. The properties of the test piece are shown in Table 1.

[0040] Embodiment 3 The epoxy resin composition provided in this embodiment has a specific preparation method comprising: 301) epoxy resin, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate are mixed in a mass ratio of 3:1:1, and synthesized under the action of an imidazole catalyst to obtain a transparent toughening agent; 302) 100 parts of mixed epoxy resin and 30 parts of transparent toughening agent are mixed, and vacuum degassing and mixing are performed at 120° C. for 3 h to obtain a first mixed solution; 103) Cool the first mixed solution to 85°C, add 0.6 parts of defoaming agent, 0.6 parts of ultraviolet absorber, 0.6 parts of antioxidant, 0.6 parts of light stabilizer and 0.1 parts of fluorescent agent, keep the mixture warm and vacuum degas for 1.5 hours to obtain a second mixed solution; 304) The second mixed solution is cooled to 60-70°C, 2 parts of curing agent and 2 parts of accelerator are added, the mixture is kept warm and vacuumed for degassing and mixing for 0.3-0.4h, and the mixture is unloaded while hot to obtain an epoxy resin composition.

[0041] The mixed epoxy resin includes, by weight, 50 parts of bisphenol A liquid epoxy resin, 10 parts of novolac epoxy resin, 10 parts of alicyclic epoxy resin and 30 parts of bisphenol A solid epoxy resin; Among them, the bisphenol A type liquid epoxy resin is epoxy resin 127; the bisphenol A type solid epoxy resin is epoxy resin E20; the novolac epoxy resin is novolac epoxy resin F44; The alicyclic epoxy resin is alicyclic epoxy resin CY184; The accelerator is an imidazole accelerator terminated with an inert group; The accelerator is prepared in the same manner as in Example 1; The UV absorber is phenyl o-hydroxybenzoate; The antioxidant is antioxidant 1010; The light stabilizer is bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate; The fluorescent brightener is fluorescent brightener OB-1; The defoamer is defoamer BYK-A530; The curing agent is 4,4'-diaminodiphenyl sulfone.

[0042] The present invention also provides a method for preparing an epoxy resin prepreg, comprising the following steps: 305) preparing the obtained epoxy resin composition into an adhesive film, wherein the coating temperature of the epoxy resin composition when coating the adhesive film is 70° C. and the adhesive content is 45%; 306) The adhesive film and the reinforcing material are hot-pressed to obtain an epoxy resin prepreg, wherein the pressing temperature when the adhesive film and the reinforcing material are hot-pressed is 70° C., and the mass percentage of the epoxy resin composition in the epoxy resin prepreg is 70%.

[0043] The epoxy resin composition was poured into a sample mold, cured at 80°C for 30 min, and cured at 120°C for 60 min to obtain a test piece. The properties of the test piece are shown in Table 1.

[0044] Embodiment 4 The epoxy resin composition provided in this embodiment has a specific preparation method comprising: 401) epoxy resin, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate are mixed in a mass ratio of 3:8:1, and synthesized under the action of an organic metal catalyst to obtain a transparent toughening agent; 402) 100 parts of mixed epoxy resin and 20 parts of transparent toughening agent are mixed, and vacuum degassing and mixing are performed at 125° C. for 2.5 hours to obtain a first mixed solution; 403) Cool the first mixed solution to 80°C, add 0.3 parts of defoaming agent, 0.5 parts of ultraviolet absorber, 0.5 parts of antioxidant, 0.4 parts of light stabilizer and 0.025 parts of fluorescent agent, keep warm, vacuum and degas for 1 hour to obtain a second mixed solution; 404) The second mixed solution is cooled to 65°C, 4.5 parts of curing agent and 2 parts of accelerator are added, the mixture is kept warm and vacuumed for degassing for 0.3h, and the mixture is unloaded while hot to obtain an epoxy resin composition.

[0045] The mixed epoxy resin includes, by weight, 50 parts of bisphenol A liquid epoxy resin, 10 parts of novolac epoxy resin, 110 parts of alicyclic epoxy resin and 30 parts of bisphenol A solid epoxy resin; Among them, the bisphenol A type liquid epoxy resin is epoxy resin 128 and epoxy resin 127, and the mass ratio of epoxy resin 128 to epoxy resin 127 is 1:1; the bisphenol A type solid epoxy resin is epoxy resin E20 and epoxy resin E909, and the mass ratio of epoxy resin E20 to epoxy resin E909 is 1:1; the novolac epoxy resin is novolac epoxy resin F51 and novolac epoxy resin F48, and the mass ratio of novolac epoxy resin F51 to novolac epoxy resin F48 is 1:1; The alicyclic epoxy resin is alicyclic epoxy resin AG-80 and alicyclic epoxy resin CY183, and the mass ratio of alicyclic epoxy resin AG-80 and alicyclic epoxy resin CY183 is 1:1; The accelerator is prepared in the same manner as in Example 1; The ultraviolet absorber is 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole; The antioxidant is antioxidant 1010; The light stabilizer is bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate; The fluorescent brightener is fluorescent brightener OB-1; The defoamer is defoamer BYK-A530; The curing agent is dicyandiamide.

[0046] The present invention also provides a method for preparing an epoxy resin prepreg, comprising the following steps: 405) preparing the obtained epoxy resin composition into an adhesive film, wherein the coating temperature of the epoxy resin composition when coating the adhesive film is 70° C. and the adhesive content is 40%; 406) The adhesive film and the reinforcing material are hot-pressed to obtain an epoxy resin prepreg, wherein the pressing temperature when the adhesive film and the reinforcing material are hot-pressed is 70° C., and the mass percentage of the epoxy resin composition in the epoxy resin prepreg is 60%.

[0047] The epoxy resin composition was poured into a sample mold, cured at 80°C for 30 min, and cured at 120°C for 60 min to obtain a test piece. The properties of the test piece are shown in Table 1.

[0048] Table 1 Test results of epoxy resin matrix properties of Examples 1 to 4 and Comparative Example 1

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an epoxy resin composition, characterized in that: The steps include: The epoxy resin, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate are mixed and synthesized under the action of a catalyst to obtain a transparent toughening agent; Mix the mixed epoxy resin and the transparent toughening agent, and perform vacuum degassing and mixing at 120-130° C. for 1-3 hours to obtain a first mixed solution; The first mixed solution is cooled to 70-85° C., a defoamer, an ultraviolet absorber, an antioxidant, a light stabilizer and a fluorescent agent are added, and the mixture is kept warm, vacuumed, degassed and mixed for 1-1.5 hours to obtain a second mixed solution; The second mixed liquid is cooled to 60-70° C., a curing agent and an accelerator are added, the mixture is kept warm, vacuumed, degassed and mixed for 0.3-0.4 h, and the mixture is unloaded while hot to obtain an epoxy resin composition.

2. The method for preparing the epoxy resin composition according to claim 1, wherein: According to weight fraction, the mixed epoxy resin comprises 50-60 parts of bisphenol A type liquid epoxy resin, 5-10 parts of novolac epoxy resin, 5-10 parts of alicyclic epoxy resin and 20-40 parts of bisphenol A solid epoxy resin.

3. The method for preparing the epoxy resin composition according to claim 1, wherein: The mass ratio of epoxy resin, 2,4-diphenylmethane diisocyanate and 4,4-diphenylmethane diisocyanate is 3:(1-10):1; the catalyst is one of an organic metal catalyst, an inorganic metal salt catalyst or an imidazole catalyst.

4. The method for preparing the epoxy resin composition according to claim 1, wherein: The accelerator is an imidazole accelerator terminated with an inert group; the preparation process of the accelerator includes: Mix 2-ethyl-4-methylimidazole and an organic acid aqueous solution in a mass ratio of 100:(50-200), heat to 100-120°C, reflux, stir and keep warm for 1-1.5h, cool to 60-85°C, transfer to an oven and bake until constant weight is obtained to obtain a promoter; Wherein, in the organic acid aqueous solution, the mass ratio of organic acid to water is 1:(5-12); The organic acid includes one of acetic acid, lactic acid, cyanuric acid, salicylic acid or acrylic acid.

5. The method for preparing the epoxy resin composition according to claim 1, wherein: The mass ratio of the mixed epoxy resin and the transparent toughening agent is 100:(5-30); The mass ratio of mixed epoxy resin to defoamer is 100:(0.1-3.0); The mass ratio of the mixed epoxy resin to the ultraviolet absorber is 100:(0.1-5); The mass ratio of the mixed epoxy resin to the antioxidant is 100:(0.1-5); The mass ratio of mixed epoxy resin to light stabilizer is 100:(0.1-1.0); The mass ratio of mixed epoxy resin to fluorescent agent is 100:(0.01-1.0); The mass ratio of mixed epoxy resin to curing agent is 100:(2-10); The mass ratio of mixed epoxy resin to accelerator is 100:(2-10).

6. The method for preparing the epoxy resin composition according to claim 2, wherein: The bisphenol A type liquid epoxy resin is at least one of epoxy resin 128 and epoxy resin 127; The bisphenol A type solid epoxy resin is one or a mixture of epoxy resin E20, epoxy resin E14, epoxy resin E901 or epoxy resin E909; The novolac epoxy resin is one or a mixture of novolac epoxy resin F51, novolac epoxy resin F44 or novolac epoxy resin F48; The alicyclic epoxy resin is one of alicyclic epoxy resin AG-80, alicyclic epoxy resin 2021P, alicyclic epoxy resin CY179, alicyclic epoxy resin CY184, alicyclic epoxy resin CY183, and alicyclic epoxy resin ERL4221, or a mixture of several of them.

7. The method for preparing the epoxy resin composition according to claim 1, wherein: The ultraviolet absorber is a mixture of one or more of 2-(4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl)-5-octoxyphenol, phenyl o-hydroxybenzoate, 2-hydroxy-4-n-octoxybenzophenone, and 2-(2'-hydroxy-3',5'-di-tert-phenyl)-5-chlorobenzotriazole; The antioxidant is one of amine antioxidants, hindered phenol antioxidants or phosphite-based high-efficiency antioxidants; The light stabilizer is a mixture of one or more of hexamethylphosphoric triamide, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, mono(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate or 1-methyl-8-(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate; The fluorescent whitening agent is a mixture of one or more of a stilbene fluorescent whitening agent, a pyrazoline fluorescent whitening agent or a benzoxazine fluorescent whitening agent; The defoaming agent is an organosilicon defoaming agent or a polymer defoaming agent; The curing agent is dicyandiamide or 4,4'-diaminodiphenyl sulfone; The diphenylethylene fluorescent brightener is fluorescent brightener OB-1 or fluorescent brightener FP-127; The pyrazoline fluorescent brightener is a 2-pyrazoline fluorescent brightener; The benzoxazine fluorescent whitening agent is at least one of a BBOT benzoxazine fluorescent whitening agent or a KCB benzoxazine fluorescent whitening agent.

8. An epoxy resin composition obtained based on the epoxy resin composition preparation method according to any one of claims 1 to 7.

9. An epoxy resin prepreg, characterized in that: It comprises a reinforcing material and the epoxy resin composition as claimed in claim 8, wherein the mass percentage of the epoxy resin composition in the epoxy resin prepreg is 55-70%.

10. A method for preparing an epoxy resin prepreg, characterized in that: The steps include: Preparing the epoxy resin composition as claimed in claim 8 into a film; The adhesive film and the reinforcing material are hot-pressed to obtain epoxy resin prepreg.

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