High-refractive-index high-toughness anti-yellowing epoxy resin composite material and preparation method thereof

Abstract

The invention relates to a high-refractive-index, high-toughness and yellowing-resistant epoxy resin composite material and a preparation method thereof, and belongs to the technical field of high polymer material preparation. The epoxy resin composite material comprises 100-140 parts of an epoxy prepolymer, 20-50 parts of a curing agent, 0.2-5 parts of rubber particles, 0.1-4 parts of an anti-yellowing additive and 5-20 parts of a functional auxiliary agent, and through the synergistic effect of the raw materials, the prepared epoxy resin has high refractive index, high toughness and excellent anti-yellowing performance.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material preparation, and relates to a high-refractive-index, high-toughness, yellowing-resistant epoxy resin composite material and a preparation method thereof. Background Art

[0002] Epoxy resin is a general term for organic compounds with at least two epoxy groups. Generally, aliphatic and aromatic groups are used as the main polymer skeletons, and there are many reaction sites such as -OH that can be modified. Epoxy resin is mainly cured by opening the epoxy group to form a three-dimensional network structure. It is a thermosetting system material with the advantages of easy processing, good adhesion, low creep, and solvent resistance. It is often used in adhesives, electronic material packaging and other fields. However, epoxy resin also has certain defects. It needs to add a curing agent during curing, and it is easy to generate internal stress during curing, and the toughness is poor. At the same time, the refractive index is limited and the yellowing resistance is poor. These factors limit the application of epoxy resin in high-end products.

[0003] There are mainly the following methods for high refractive index epoxy resins: one is to introduce high molar refractive index groups and atoms such as benzene rings and S atoms into the structure of epoxy resins through molecular structure design, or to increase the refractive index of the curing agent by designing the structure of the epoxy curing agent, and then obtain high refractive index organic optical materials through two-component curing of the curing agent and epoxy prepolymer; another method is to introduce high refractive index nanoparticles into the epoxy resin to achieve a high refractive index of the epoxy resin composite material. However, the research on high refractive index epoxy resins using the above two technical routes still has the following main problems: for high refractive index epoxy resins, due to the need to introduce groups and atoms with high molar refractive index, the currently reported synthesis process is generally cumbersome and complicated, with high cost and low yield; the currently widely used high refractive index polymer structures all contain a large number of aromatic ring structures, but this type of structure is very easy to oxidize and cause the resin to turn yellow, the material has poor yellowing resistance and a low service life; for nano-hybrid epoxy resin composites, inorganic nanoparticles are difficult to disperse evenly in the polymer matrix, the inorganic phase and the organic phase cannot be well soluble, and nanoparticles are prone to agglomeration, resulting in poor synthetic stability of the high refractive index hybrid resin; in addition, for an optical epoxy resin material with application value, in addition to having a high refractive index, high toughness and yellowing resistance are also important indicators to measure its value.

[0004] Therefore, how to develop yellowing-resistant epoxy resin composite materials with both high refractive index and high toughness is a difficult problem that needs to be solved urgently. Summary of the invention

[0005] The purpose of the present invention is to provide a high-refractive index, high-toughness, yellowing-resistant epoxy resin composite material and a preparation method thereof. The epoxy resin prepared by the present invention has a high refractive index, high toughness and excellent yellowing resistance through the synergistic effect of various raw materials.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A high-refractive-index, high-toughness, yellowing-resistant epoxy resin composite material comprises the following raw material components by weight: 100-140 parts of epoxy prepolymer, 20-50 parts of curing agent, 0.2-5 parts of rubber particles, 0.1-4 parts of yellowing-resistant additive, and 5-20 parts of functional additive.

[0008] Furthermore, the epoxy prepolymer is selected from one or more of bisphenol A epoxy resin prepolymer, bismaleimide-modified phenolic epoxy resin prepolymer, cyclopentyltrimethoxysilane prepolymer, polyphenylmethylsiloxane prepolymer, tetrabromobisphenol A epoxy resin prepolymer, 1,2-cyclohexanedicarboxylic acid diglycidyl ester, glycerol epoxy resin prepolymer, 2,2'-dimercaptodiethyl sulfide diglycidyl ether epoxy resin prepolymer and 3,3'-dimercaptodiphenyl sulfone epoxy resin prepolymer.

[0009] Furthermore, the curing agent is selected from one or more of o-phenylenedithiol, ethylenediamine, methylhexahydrophthalic anhydride, triethylamine, bicyclic amidine, isophoronediamine, metaphenylenediamine, sebacic acid dihydrazide, stannous chloride and boron trifluoride complex.

[0010] Furthermore, the rubber particles are selected from one of styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer and polybutadiene rubber particles, and the average particle size of the rubber particles is 2-40 nm, and the particle size distribution index is 1-1.10.

[0011] Furthermore, the surface of the rubber particles is grafted, and the reagent used for the grafting treatment is selected from one or more of styrene, maleic anhydride, acrylonitrile, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and bis(γ-triethoxysilylpropyl)tetrasulfide.

[0012] Furthermore, the anti-yellowing additive is a silicon dioxide particle-loaded antioxidant, and the antioxidant is N-phenyl-p-phenylenediamine.

[0013] Furthermore, the silicon dioxide is mesoporous silicon dioxide prepared by a gas phase method, the average particle size of the mesoporous silicon dioxide is 3-45 nm, the particle size distribution width is 1-1.06, and the porosity is 60-95%.

[0014] Furthermore, the preparation method of the anti-yellowing additive is:

[0015] a. Under a nitrogen environment, 1.5-3.5 parts by weight of N-phenyl-p-phenylenediamine and 5-10 parts by weight of toluene were uniformly mixed, and then 0.4-0.8 parts by weight of 3-isocyanatepropyltriethoxysilane and 0.05-0.15 parts by weight of dibutyltin laurate were added, the temperature was raised to 45-55°C, and the mixture was stirred at a speed of 100-300 rpm for 5-7 hours. The toluene was removed by rotary evaporation at 60°C, and then the product A was obtained by redissolving the mixture with 4-8 parts by weight of 70-80wt% ethanol solution;

[0016] b. After mixing 4.8-6.2 parts by weight of mesoporous silica with 20-30 parts by weight of anhydrous ethanol, the temperature is raised to 35-45°C, stirred at 80-200 rpm for 3-5 hours, all the product A is poured in, stirred at 45-55°C at 50-90 rpm for 12-36 hours, the stirring is stopped, washed with anhydrous ethanol and then extracted with anhydrous ethanol for 72 hours, and the obtained product is dried to constant weight to obtain the anti-yellowing additive.

[0017] Furthermore, the functional auxiliary agent is selected from one or more of ethylene dioleamide, ethylene bis stearic acid amide, alkylene glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, benzyl glycidyl ether, neopentyl glycol diglycidyl ether, phenyl glycidyl ether, styrene, ethyl methacrylate and tribromobenzene.

[0018] Furthermore, the preparation method comprises the following steps:

[0019] (1) Prepare the raw materials in portions, mix the rubber particles, the anti-yellowing additive and the functional additive, and stir at 25 to 50° C. for 3 to 12 hours to obtain a mixture A;

[0020] (2) adding epoxy prepolymer and curing agent to mixed material A, stirring at 25 to 50° C. for 1 to 6 hours, and then sealing and standing for 24 to 72 hours to obtain mixed material B;

[0021] (3) The mixed material B is heated at 50-80° C. for 2-12 h, and then the temperature is raised to 100-155° C. and kept warm for 3-9 h, thereby obtaining an epoxy resin composite material with high refractive index, high toughness and yellowing resistance.

[0022] Beneficial effects of the present invention:

[0023] (1) The rubber particles in the present invention have good elasticity and deformation ability. By adjusting the particle size and distribution of the rubber particles, it is helpful to evenly disperse them in the epoxy resin. When the material is subjected to external force, it can absorb and disperse energy to prevent the rapid expansion of cracks, thereby achieving a toughening effect. By grafting and modifying the surface of the rubber particles, the grafting agents on the surface, such as styrene, maleic anhydride, etc., can produce covalent bonds or strong intermolecular interactions with the molecular chains of the epoxy prepolymer, so that it has good compatibility with the epoxy resin. While significantly improving the toughness of the epoxy resin composite material, it helps to reduce the refractive index difference at the interface, making the propagation of light in the material more uniform, thereby improving the refractive index as a whole.

[0024] (2) The anti-yellowing additive in the present invention is an antioxidant loaded on silica particles. The antioxidant N-phenyl-p-phenylenediamine can react with free radicals generated during the oxidation process at the molecular level, capture them and terminate the oxidation chain reaction, thereby effectively inhibiting the yellowing phenomenon of the material caused by oxidation; by adjusting the particle size and distribution of mesoporous silica, more surface area is provided, the interaction with surrounding molecules is enhanced, and the migration failure of components such as antioxidants in conventional composite materials is avoided, thereby improving the anti-yellowing performance of the composite material.

[0025] (3) The present invention adds special functional additives. The functional additives such as ethylene dioleamide and alkylene glycidyl ether contain active functional groups and can participate in the curing reaction of epoxy resin. On the one hand, they can promote the uniform dispersion of rubber particles and anti-yellowing additives and adjust the crosslinking density between epoxy prepolymer and curing agent. On the other hand, some components in the functional additives can react chemically with the curing agent to improve the physical properties of the material, thereby further improving the toughness and refractive index of the composite material.

[0026] (4) The epoxy resin prepared by the present invention has high refractive index, high toughness and excellent yellowing resistance through the synergistic effect of various raw materials. DETAILED DESCRIPTION

[0027] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0028] Example 1

[0029] A high-refractive-index, high-toughness, yellowing-resistant epoxy resin composite material. The epoxy resin composite material of this embodiment comprises the following raw material components by weight: 100 parts of epoxy prepolymer, 20 parts of curing agent, 5 parts of rubber particles, 4 parts of yellowing-resistant additives, and 20 parts of functional additives.

[0030] The epoxy prepolymer of this embodiment is composed of bisphenol A epoxy resin prepolymer, tetrabromobisphenol A epoxy resin prepolymer and 3,3'-dimercaptodiphenyl sulfone epoxy resin prepolymer in a mass ratio of 2:1:1.

[0031] The curing agent of this embodiment is composed of methyl hexahydrophthalic anhydride, m-phenylenediamine and sebacic acid dihydrazide in a mass ratio of 3:2:1.

[0032] The rubber particles of this embodiment are styrene-butadiene-styrene block copolymer, with an average particle size of 35 nm and a particle size distribution index of 1.09.

[0033] The surface of the rubber particles of this embodiment is grafted, and the reagents used for the grafting treatment are styrene and bis(γ-triethoxysilylpropyl)tetrasulfide; the steps of the grafting treatment on the surface of the rubber particles are: styrene-butadiene-styrene block copolymer, styrene, bis(γ-triethoxysilylpropyl)tetrasulfide, benzoyl peroxide and toluene are mixed in a mass ratio of 1:0.5:0.2:0.05:10, heated to 80°C and stirred for 6h, the resulting solution is poured into a large amount of methanol for precipitation, and the product is obtained by filtering through a 200-mesh filter cloth, washed with methanol, and dried in an oven at 60°C to constant weight to obtain a styrene-butadiene-styrene block copolymer after the surface grafting treatment.

[0034] The anti-yellowing additive of this embodiment is a silicon dioxide particle-loaded antioxidant, and the antioxidant of this embodiment is N-phenyl-p-phenylenediamine.

[0035] The silicon dioxide in this embodiment is mesoporous silicon dioxide prepared by a gas phase method. The average particle size of the mesoporous silicon dioxide is 45 nm, the particle size distribution width is 1.06, and the porosity is 60%.

[0036] The preparation method of the anti-yellowing additive of this embodiment is:

[0037] a. Under nitrogen environment, 2.5 parts by weight of N-phenyl-p-phenylenediamine and 7.5 parts by weight of toluene were mixed uniformly, and then 0.6 parts by weight of 3-isocyanatepropyltriethoxysilane and 0.1 parts by weight of dibutyltin laurate were added, the temperature was raised to 50°C, stirred at 200 rpm for 6 hours, and the toluene was removed by rotary evaporation at 60°C, and then redissolved with 6 parts by weight of 75wt% ethanol solution to obtain product A;

[0038] b. After mixing 5.5 parts by weight of mesoporous silica with 25 parts by weight of anhydrous ethanol, the temperature was raised to 40°C, and stirred at 140 rpm for 4 hours. Then, all of the product A was poured in, and stirred at 70 rpm for 24 hours at 50°C. After stopping the stirring, the mixture was washed with anhydrous ethanol and then extracted with anhydrous ethanol for 72 hours. The obtained product was dried to constant weight to obtain the anti-yellowing additive.

[0039] The functional additive of this embodiment is composed of ethylene dioleamide and phenyl glycidyl ether in a mass ratio of 3:1.

[0040] The preparation method of this embodiment comprises the following steps:

[0041] (1) Prepare the raw materials in portions, mix the rubber particles, the anti-yellowing additive and the functional additive, and stir at 50° C. for 12 hours to obtain a mixture A;

[0042] (2) adding epoxy prepolymer and curing agent to mixed material A, stirring at 25° C. for 6 h, and then sealing and standing for 24 h to obtain mixed material B;

[0043] (3) Mixture B is heated at 80° C. for 12 h, and then the temperature is raised to 100° C. and kept at this temperature for 9 h, thereby obtaining an epoxy resin composite material with high refractive index, high toughness and yellowing resistance.

[0044] Example 2

[0045] A high-refractive-index, high-toughness, yellowing-resistant epoxy resin composite material. The epoxy resin composite material of this embodiment comprises the following raw material components by weight: 140 parts of epoxy prepolymer, 50 parts of curing agent, 0.2 parts of rubber particles, 0.1 parts of yellowing-resistant additive, and 5 parts of functional additives.

[0046] The epoxy prepolymer of this embodiment is composed of bismaleimide-modified phenolic epoxy resin prepolymer, cyclopentyltrimethoxysilane prepolymer and 2,2'-dimercaptodiethyl sulfide diglycidyl ether epoxy resin prepolymer in a mass ratio of 2:1:3.

[0047] The curing agent of this embodiment is composed of bicyclic amidine, isophorone diamine, meta-phenylenediamine and sebacic acid dihydrazide in a mass ratio of 2:4:1:1.

[0048] The rubber particles of this embodiment are styrene-ethylene-butylene-styrene block copolymer, with an average particle size of 35 nm and a particle size distribution index of 1.09.

[0049] The surface of the rubber particles of this embodiment is grafted, and the reagent used for the grafting treatment is selected from styrene and bis(γ-triethoxysilylpropyl)tetrasulfide; the steps of grafting the surface of the rubber particles are: styrene-ethylene-butylene-styrene block copolymer, styrene, bis(γ-triethoxysilylpropyl)tetrasulfide, benzoyl peroxide and toluene are mixed in a mass ratio of 1:0.4:0.15:0.03:8, heated to 70°C and stirred for 5h, the resulting solution is poured into a large amount of methanol for precipitation, and the product is obtained by filtering through a 200-mesh filter cloth, washed with methanol, and dried in an oven at 60°C to constant weight to obtain a styrene-ethylene-butylene-styrene block copolymer after the surface grafting treatment.

[0050] The anti-yellowing additive of this embodiment is a silicon dioxide particle-loaded antioxidant, and the antioxidant of this embodiment is N-phenyl-p-phenylenediamine.

[0051] The silicon dioxide in this embodiment is mesoporous silicon dioxide prepared by a gas phase method. The average particle size of the mesoporous silicon dioxide is 3 nm, the particle size distribution width is 1.06, and the porosity is 60%.

[0052] The preparation method of the anti-yellowing additive of this embodiment is:

[0053] a. Under nitrogen environment, 2.5 parts by weight of N-phenyl-p-phenylenediamine and 7.5 parts by weight of toluene were mixed uniformly, and then 0.6 parts by weight of 3-isocyanatepropyltriethoxysilane and 0.1 parts by weight of dibutyltin laurate were added, the temperature was raised to 50°C, stirred at 200 rpm for 6 hours, and the toluene was removed by rotary evaporation at 60°C, and then redissolved with 6 parts by weight of 75wt% ethanol solution to obtain product A;

[0054] b. After mixing 5.5 parts by weight of mesoporous silica with 25 parts by weight of anhydrous ethanol, the temperature was raised to 40°C, and stirred at 140 rpm for 4 hours. Then, all of the product A was poured in, and stirred at 70 rpm for 24 hours at 50°C. After stopping the stirring, the mixture was washed with anhydrous ethanol and then extracted with anhydrous ethanol for 72 hours. The obtained product was dried to constant weight to obtain the anti-yellowing additive.

[0055] The functional additive of this embodiment is composed of ethylene bisstearic acid amide, alkylene glycidyl ether and styrene in a mass ratio of 1:3:1.

[0056] The preparation method of this embodiment comprises the following steps:

[0057] (1) Prepare the raw materials in portions, mix the rubber particles, the anti-yellowing additive and the functional additive, and stir at 25° C. for 3 h to obtain a mixture A;

[0058] (2) adding epoxy prepolymer and curing agent to mixed material A, stirring at 50° C. for 1 h, and then sealing and standing for 72 h to obtain mixed material B;

[0059] (3) Mixture B is heated at 50° C. for 2 h, and then the temperature is raised to 135° C. and kept at this temperature for 9 h, thereby obtaining an epoxy resin composite material with high refractive index, high toughness and yellowing resistance.

[0060] Example 3

[0061] A high-refractive-index, high-toughness, yellowing-resistant epoxy resin composite material. The epoxy resin composite material of this embodiment comprises the following raw material components by weight: 120 parts of epoxy prepolymer, 30 parts of curing agent, 5 parts of rubber particles, 2.4 parts of yellowing-resistant additive, and 10 parts of functional additive.

[0062] The epoxy prepolymer of this embodiment is composed of cyclopentyltrimethoxysilane prepolymer, polyphenylmethylsiloxane prepolymer and tetrabromobisphenol A type epoxy resin prepolymer in a mass ratio of 1:1:2.

[0063] The curing agent of this embodiment is composed of isophorone diamine and meta-phenylenediamine in a mass ratio of 4:1.

[0064] The rubber particles in this embodiment are polybutadiene rubber particles, with an average particle size of 40 nm and a particle size distribution index of 1.

[0065] The surface of the rubber particles of this embodiment is grafted, and the reagents used for the grafting treatment are acrylonitrile and γ-aminopropyltriethoxysilane; the steps of the grafting treatment on the surface of the rubber particles are: polybutadiene rubber particles, acrylonitrile, γ-aminopropyltriethoxysilane, benzoyl peroxide and toluene are mixed in a mass ratio of 0.8:0.3:0.1:0.02:6, heated to 40°C and stirred for 4 hours, the resulting solution is poured into a large amount of methanol for precipitation, the product is filtered through a 200-mesh filter cloth to obtain a product, washed with methanol, and dried in an oven at 60°C to constant weight to obtain polybutadiene rubber particles after the surface grafting treatment.

[0066] The anti-yellowing additive of this embodiment is a silicon dioxide particle-loaded antioxidant, and the antioxidant of this embodiment is N-phenyl-p-phenylenediamine.

[0067] The silicon dioxide in this embodiment is mesoporous silicon dioxide prepared by a gas phase method. The average particle size of the mesoporous silicon dioxide is 3 nm, the particle size distribution width is 1.01, and the porosity is 85%.

[0068] The preparation method of the anti-yellowing additive of this embodiment is:

[0069] a. Under nitrogen environment, 2.5 parts by weight of N-phenyl-p-phenylenediamine and 7.5 parts by weight of toluene were mixed uniformly, and then 0.6 parts by weight of 3-isocyanatepropyltriethoxysilane and 0.1 parts by weight of dibutyltin laurate were added, the temperature was raised to 50°C, stirred at 200 rpm for 6 hours, and the toluene was removed by rotary evaporation at 60°C, and then redissolved with 6 parts by weight of 75wt% ethanol solution to obtain product A;

[0070] b. After mixing 5.5 parts by weight of mesoporous silica with 25 parts by weight of anhydrous ethanol, the temperature was raised to 40°C, and stirred at 140 rpm for 4 hours. Then, all of the product A was poured in, and stirred at 70 rpm for 24 hours at 50°C. After stopping the stirring, the mixture was washed with anhydrous ethanol and then extracted with anhydrous ethanol for 72 hours. The obtained product was dried to constant weight to obtain the anti-yellowing additive.

[0071] The functional additive of this embodiment is composed of 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether and ethyl methacrylate in a mass ratio of 1:1:1.

[0072] The preparation method of this embodiment comprises the following steps:

[0073] (1) Prepare the raw materials in portions, mix the rubber particles, the anti-yellowing additive and the functional additive, and stir at 35° C. for 5 h to obtain a mixture A;

[0074] (2) adding epoxy prepolymer and curing agent to mixed material A, stirring at 40° C. for 2 h, and then sealing and standing for 32 h to obtain mixed material B;

[0075] (3) Mixture B is heated at 60° C. for 4 h, and then the temperature is raised to 145° C. and kept at this temperature for 6 h, thereby obtaining an epoxy resin composite material with high refractive index, high toughness and yellowing resistance.

[0076] Example 4

[0077] A high-refractive-index, high-toughness, yellowing-resistant epoxy resin composite material. The epoxy resin composite material of this embodiment comprises the following raw material components by weight: 130 parts of epoxy prepolymer, 40 parts of curing agent, 4 parts of rubber particles, 1 part of yellowing-resistant additive, and 15 parts of functional additives.

[0078] The epoxy prepolymer of this embodiment is composed of bisphenol A epoxy resin prepolymer, 1,2-cyclohexanedicarboxylic acid diglycidyl ester, glycerol epoxy resin and 2,2'-dimercaptodiethyl sulfide diglycidyl ether epoxy resin prepolymer in a mass ratio of 4:2:1:3.

[0079] The curing agent of this embodiment is composed of o-phthalic acid dithiol, sebacic acid dihydrazide and stannous chloride in a mass ratio of 2:1:1.

[0080] The rubber particles in this embodiment are polybutadiene rubber particles, with an average particle size of 10 nm and a particle size distribution index of 1.02.

[0081] The surface of the rubber particles of this embodiment is grafted, and the reagents used for the grafting treatment are γ-glycidyloxypropyltrimethoxysilane and bis(γ-triethoxysilylpropyl)tetrasulfide; the steps of grafting the surface of the rubber particles are: polybutadiene rubber particles, γ-glycidyloxypropyltrimethoxysilane, bis(γ-triethoxysilylpropyl)tetrasulfide, benzoyl peroxide and toluene are mixed in a mass ratio of 1:0.2:0.1:0.04:8, heated to 60°C and stirred for 5.5h, the obtained solution is poured into a large amount of methanol for precipitation, and the product is obtained by filtering through a 200-mesh filter cloth, washed with methanol, and dried in an oven at 60°C to constant weight to obtain polybutadiene rubber particles after the surface grafting treatment.

[0082] The anti-yellowing additive of this embodiment is a silicon dioxide particle-loaded antioxidant, and the antioxidant of this embodiment is N-phenyl-p-phenylenediamine.

[0083] The silicon dioxide in this embodiment is mesoporous silicon dioxide prepared by a gas phase method. The average particle size of the mesoporous silicon dioxide is 3 nm, the particle size distribution width is 1.06, and the porosity is 60%.

[0084] The preparation method of the anti-yellowing additive of this embodiment is:

[0085] a. Under nitrogen environment, 2.5 parts by weight of N-phenyl-p-phenylenediamine and 7.5 parts by weight of toluene were mixed uniformly, and then 0.6 parts by weight of 3-isocyanatepropyltriethoxysilane and 0.1 parts by weight of dibutyltin laurate were added, the temperature was raised to 50°C, stirred at 200 rpm for 6 hours, and the toluene was removed by rotary evaporation at 60°C, and then redissolved with 6 parts by weight of 75wt% ethanol solution to obtain product A;

[0086] b. After mixing 5.5 parts by weight of mesoporous silica with 25 parts by weight of anhydrous ethanol, the temperature was raised to 40°C, and stirred at 140 rpm for 4 hours. Then, all of the product A was poured in, and stirred at 70 rpm for 24 hours at 50°C. After stopping the stirring, the mixture was washed with anhydrous ethanol and then extracted with anhydrous ethanol for 72 hours. The obtained product was dried to constant weight to obtain the anti-yellowing additive.

[0087] The functional additive of this embodiment is composed of ethylene bisstearic acid amide, alkylene glycidyl ether and styrene in a mass ratio of 1:3:1.

[0088] The preparation method of this embodiment comprises the following steps:

[0089] (1) Prepare the raw materials in portions, mix the rubber particles, the anti-yellowing additive and the functional additive, and stir at 40° C. for 8 h to obtain a mixture A;

[0090] (2) adding epoxy prepolymer and curing agent to mixed material A, stirring at 50° C. for 5 h, and then sealing and standing for 40 h to obtain mixed material B;

[0091] (3) Mixture B is heated at 60° C. for 11 h, and then the temperature is raised to 110° C. and kept at this temperature for 9 h, thereby obtaining an epoxy resin composite material having a high refractive index, high toughness and yellowing resistance.

[0092] Example 5

[0093] A high-refractive-index, high-toughness, yellowing-resistant epoxy resin composite material. The epoxy resin composite material of this embodiment comprises the following raw material components by weight: 140 parts of epoxy prepolymer, 50 parts of curing agent, 0.2 parts of rubber particles, 0.1 parts of yellowing-resistant additive, and 18 parts of functional additives.

[0094] The epoxy prepolymer of this embodiment is composed of bisphenol A epoxy resin prepolymer, polyphenylmethylsiloxane prepolymer, tetrabromobisphenol A epoxy resin prepolymer and 3,3'-dimercaptodiphenyl sulfone epoxy resin prepolymer in a mass ratio of 5:2:1:3.

[0095] The curing agent of this embodiment is composed of o-phthalic acid dithiol, methyl hexahydrophthalic anhydride and triethylamine in a mass ratio of 3:1:1.

[0096] The rubber particles of this embodiment are styrene-butadiene-styrene block copolymer, with an average particle size of 20 nm and a particle size distribution index of 1.05.

[0097] The surface of the rubber particles of this embodiment is grafted, and the reagents used for the grafting treatment are maleic anhydride and bis(γ-triethoxysilylpropyl)tetrasulfide; the steps of grafting the surface of the rubber particles are: styrene-butadiene-styrene block copolymer, maleic anhydride, bis(γ-triethoxysilylpropyl)tetrasulfide, benzoyl peroxide and toluene are mixed in a mass ratio of 1.2:0.3:0.12:0.03:12, heated to 75°C and stirred for 5h, the resulting solution is poured into a large amount of methanol for precipitation, and the product is obtained by filtering through a 200-mesh filter cloth, washed with methanol, and dried in an oven at 60°C to constant weight to obtain a styrene-butadiene-styrene block copolymer after the surface grafting treatment.

[0098] The anti-yellowing additive of this embodiment is a silicon dioxide particle-loaded antioxidant, and the antioxidant of this embodiment is N-phenyl-p-phenylenediamine.

[0099] The silicon dioxide in this embodiment is mesoporous silicon dioxide prepared by a gas phase method. The average particle size of the mesoporous silicon dioxide is 23 nm, the particle size distribution width is 1.06, and the porosity is 95%.

[0100] The preparation method of the anti-yellowing additive of this embodiment is:

[0101] a. Under nitrogen environment, 2.5 parts by weight of N-phenyl-p-phenylenediamine and 7.5 parts by weight of toluene were mixed uniformly, and then 0.6 parts by weight of 3-isocyanatepropyltriethoxysilane and 0.1 parts by weight of dibutyltin laurate were added, the temperature was raised to 50°C, stirred at 200 rpm for 6 hours, and the toluene was removed by rotary evaporation at 60°C, and then redissolved with 6 parts by weight of 75wt% ethanol solution to obtain product A;

[0102] b. After mixing 5.5 parts by weight of mesoporous silica with 25 parts by weight of anhydrous ethanol, the temperature was raised to 40°C, and stirred at 140 rpm for 4 hours. Then, all of the product A was poured in, and stirred at 70 rpm for 24 hours at 50°C. After stopping the stirring, the mixture was washed with anhydrous ethanol and then extracted with anhydrous ethanol for 72 hours. The obtained product was dried to constant weight to obtain the anti-yellowing additive.

[0103] The functional additive of this embodiment is composed of ethylene dioleamide, 1,6-hexanediol diglycidyl ether and ethyl methacrylate in a mass ratio of 1:2:1.

[0104] The preparation method of this embodiment comprises the following steps:

[0105] (1) Prepare the raw materials in portions, mix the rubber particles, the anti-yellowing additive and the functional additive, and stir at 40° C. for 3 h to obtain a mixture A;

[0106] (2) adding epoxy prepolymer and curing agent to mixed material A, stirring at 25° C. for 1 h, and then sealing and standing for 24 h to obtain mixed material B;

[0107] (3) Mixture B was heated at 70° C. for 4 h, and then the temperature was raised to 155° C. and kept at this temperature for 9 h, thereby obtaining an epoxy resin composite material with high refractive index, high toughness and yellowing resistance.

[0108] Comparative Example 1

[0109] On the basis of Example 3, the rubber particles were removed and replaced with an epoxy prepolymer of equal weight, and the other conditions were the same as those of Example 3.

[0110] Comparative Example 2

[0111] On the basis of Example 3, the anti-yellowing additive was removed and replaced with an epoxy prepolymer of equal weight, and other conditions were consistent with Example 3.

[0112] Comparative Example 3

[0113] On the basis of Example 3, the functional additive was removed and replaced with an epoxy prepolymer of equal weight, and other conditions were consistent with Example 3.

[0114] Comparative Example 4

[0115] On the basis of Example 3, the added amount of the functional additive was changed to 4 parts by weight, and the remaining 6 parts by weight were replaced by epoxy prepolymer. Other conditions were consistent with Example 3.

[0116] Comparative Example 5

[0117] On the basis of Example 3, the average particle size of the rubber particles was changed to 100 nm, and other conditions were consistent with those of Example 3.

[0118] Comparative Example 6

[0119] On the basis of Example 3, the average particle size of the mesoporous silica in the anti-yellowing additive was changed to 80 nm, and other conditions were consistent with Example 3.

[0120] The yellowing-resistant epoxy resin composite materials with high refractive index and high toughness prepared in Examples 1-5 and Comparative Examples 1-6 were used as samples, and their properties were characterized. The characterization items and methods are as follows:

[0121] (I) Characterization methods

[0122] 1. Refractive index test of epoxy resin composite materials

[0123] The refractive index of epoxy resin composite materials was tested using an Abbe refractometer, where a refractive index greater than 1.57 was considered a high refractive index.

[0124] 2. Toughness test of epoxy resin composites

[0125] The impact toughness index is the IZOD impact strength, which is tested in accordance with "ASTM D256-10 "Izod notched impact strength of plastic strips"", where IZOD impact strength ≥ 20J / m is high toughness.

[0126] 3. Yellowing resistance test of epoxy resin composite materials

[0127] The yellowing resistance of epoxy resin composite materials was tested according to "ASTM D1925-70 (1988) e1 "Test method for yellowness index of plastics" and "Han Xudong, Preliminary study on the factors affecting yellowing of UV-curing coatings and a simple test method for yellowing degree, China Coatings, 34, 6, 35-42, 2019", and the yellowing index Y was calculated.

[0128] According to the above test, when the yellowing index Y is less than 3%, it means that the epoxy resin composite material has good yellowing resistance.

[0129] (II) Characterization results

[0130] According to the above method, 5 samples were randomly selected from each group for testing, and then the average value was taken. The results are shown in Table 1 below:

[0131] Table 1

[0132]

[0133]

[0134] As can be seen from Table 1, the high-refractive index, high-toughness, yellowing-resistant epoxy resin composite materials prepared in Examples 1-5 of the present invention have a refractive index of ≥1.57, an IZOD impact strength of ≥20 J / m, and a yellowing index Y of ≤2.4%, indicating that the epoxy resin composite materials prepared by the present invention have high refractive index, high impact toughness and excellent yellowing resistance.

[0135] Based on Example 3, the ingredients or parameters used in Comparative Examples 1-6 were modified, and the refractive index, IZOD impact strength or yellowing index were affected, resulting in the final overall performance being inferior to that of Example 3. The presence of rubber particles can not only improve the toughness of epoxy resin composite materials, but its uniform dispersion helps to reduce the refractive index difference at the interface, thereby improving the refractive index. Therefore, the lack of rubber particles in Comparative Example 1 makes it impossible for the material to effectively absorb and disperse energy under external force impact, and the IZOD impact strength decreases while the refractive index decreases. The average particle size of rubber particles in Comparative Example 5 becomes larger, and it is easy to disperse unevenly compared with the small particle size of Example 3, thereby affecting the compatibility, and then leading to uneven stress dispersion, and reduced toughness and refractive index; Comparative Example 2 removes the anti-yellowing additive on the basis of Example 3, resulting in an increase in the yellowing index Y, and Comparative Example 6 changes the average particle size of the mesoporous silica in the anti-yellowing additive to 80nm, and the surface area is reduced compared with Example 3, so that the interaction between the anti-yellowing additive and the surrounding molecules is weakened, and the anti-yellowing performance is reduced; Comparative Example 3 removes the functional additive on the basis of Example 3, which affects the uniform dispersion of rubber particles and the anti-yellowing additive, as well as the crosslinking density between the epoxy prepolymer and the curing agent, so that the refractive index, IZOD impact strength or anti-yellowing performance are weakened, and similarly the performance of Comparative Example 4 is also affected.

[0136] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A high refractive index, high toughness and yellowing resistant epoxy resin composite material, characterized in that: The epoxy resin composite material comprises the following raw material components by weight: 100-140 parts of epoxy prepolymer, 20-50 parts of curing agent, 0.2-5 parts of rubber particles, 0.1-4 parts of anti-yellowing additive, and 5-20 parts of functional additive.

2. The high refractive index, high toughness and yellowing resistant epoxy resin composite material according to claim 1, characterized in that: The epoxy prepolymer is selected from one or more of bisphenol A epoxy resin prepolymer, bismaleimide modified phenolic epoxy resin prepolymer, cyclopentyltrimethoxysilane prepolymer, polyphenylmethylsiloxane prepolymer, tetrabromobisphenol A epoxy resin prepolymer, 1,2-cyclohexanedicarboxylic acid diglycidyl ester, glycerol epoxy resin prepolymer, 2,2'-dimercaptodiethyl sulfide diglycidyl ether epoxy resin prepolymer and 3,3'-dimercaptodiphenyl sulfone epoxy resin prepolymer.

3. The high refractive index, high toughness and yellowing resistant epoxy resin composite material according to claim 1, characterized in that: The curing agent is selected from one or more of o-phenylenedithiol, ethylenediamine, methylhexahydrophthalic anhydride, triethylamine, bicyclic amidine, isophoronediamine, metaphenylenediamine, sebacic acid dihydrazide, stannous chloride and boron trifluoride complex.

4. The high refractive index, high toughness and yellowing resistant epoxy resin composite material according to claim 1, characterized in that: The rubber particles are selected from one of styrene-butadiene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer and polybutadiene rubber particles, and the average particle size of the rubber particles is 2-40nm, and the particle size distribution index is 1-1.

10.

5. The high refractive index, high toughness and yellowing resistant epoxy resin composite material according to claim 4, characterized in that: The surface of the rubber particles is grafted, and the reagent used for the grafting treatment is selected from one or more of styrene, maleic anhydride, acrylonitrile, γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and bis(γ-triethoxysilylpropyl)tetrasulfide.

6. The high refractive index, high toughness and yellowing resistant epoxy resin composite material according to claim 1, characterized in that: The anti-yellowing additive is a silicon dioxide particle-loaded antioxidant, and the antioxidant is N-phenyl-p-phenylenediamine.

7. The high refractive index, high toughness and yellowing resistant epoxy resin composite material according to claim 6, characterized in that: The silicon dioxide is mesoporous silicon dioxide prepared by a gas phase method, the average particle size of the mesoporous silicon dioxide is 3-45nm, the particle size distribution width is 1-1.06, and the porosity is 60-95%.

8. The high refractive index, high toughness and yellowing resistant epoxy resin composite material according to claim 6, characterized in that: The preparation method of the anti-yellowing additive is: a. Under a nitrogen environment, 1.5-3.5 parts by weight of N-phenyl-p-phenylenediamine and 5-10 parts by weight of toluene were uniformly mixed, and then 0.4-0.8 parts by weight of 3-isocyanatepropyltriethoxysilane and 0.05-0.15 parts by weight of dibutyltin laurate were added, the temperature was raised to 45-55°C, and the mixture was stirred at a speed of 100-300 rpm for 5-7 hours. The toluene was removed by rotary evaporation at 60°C, and then the product A was obtained by redissolving the mixture with 4-8 parts by weight of 70-80wt% ethanol solution; b. After mixing 4.8-6.2 parts by weight of mesoporous silica with 20-30 parts by weight of anhydrous ethanol, the temperature is raised to 35-45°C, stirred at 80-200 rpm for 3-5 hours, all the product A is poured in, stirred at 45-55°C at 50-90 rpm for 12-36 hours, the stirring is stopped, washed with anhydrous ethanol and then extracted with anhydrous ethanol for 72 hours, and the obtained product is dried to constant weight to obtain the anti-yellowing additive.

9. The high refractive index, high toughness and yellowing resistant epoxy resin composite material according to claim 1, characterized in that: The functional auxiliary agent is selected from one or more of ethylene dioleamide, ethylene bis stearic acid amide, alkylene glycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, benzyl glycidyl ether, neopentyl glycol diglycidyl ether, phenyl glycidyl ether, styrene, ethyl methacrylate and tribromobenzene.

10. A method for preparing the high-refractive-index, high-toughness, yellowing-resistant epoxy resin composite material according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: (1) Prepare the raw materials in portions, mix the rubber particles, the anti-yellowing additive and the functional additive, and stir at 25 to 50° C. for 3 to 12 hours to obtain a mixture A; (2) adding epoxy prepolymer and curing agent to mixed material A, stirring at 25 to 50° C. for 1 to 6 hours, and then sealing and standing for 24 to 72 hours to obtain mixed material B; (3) The mixed material B is heated at 50-80° C. for 2-12 h, and then the temperature is raised to 100-155° C. and kept warm for 3-9 h, thereby obtaining an epoxy resin composite material with high refractive index, high toughness and yellowing resistance.

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