Modified silica grafted epoxy resin epoxy molding compound and preparation method thereof

Abstract

The present invention discloses an epoxy molding compound comprising modified silica grafted onto epoxy resin and a preparation method thereof. The epoxy molding compound comprises (A) epoxy resin; (B) phenolic resin; (C) inorganic filler; (D) silane coupling agent; (E) mold release agent; (F) curing accelerator; (G) flame retardant; (H) fumed silica; and (I) colorant. The inorganic filler is modified silica or a mixture of modified silica and unmodified silica; the content of the inorganic filler is 60-95% by weight of the total epoxy molding compound. The modified silica is silica modified by a prepolymer of polyethylene glycol and diisocyanate in the presence of a catalyst. The present invention grafts epoxy resin onto the surface of the modified silica via flexible chains. The resulting epoxy molding compound has the characteristics of high temperature resistance and high toughness, and can be used for packaging various electronic materials.

Description

Technical Field

[0001] The invention relates to an epoxy molding compound of modified silicon dioxide grafted epoxy resin and a preparation method thereof, belonging to the technical field of electronic packaging materials. Background Art

[0002] Epoxy molding compounds offer high reliability, simple production processes, and low costs. They are widely used in semiconductor devices, integrated circuits, consumer electronics, and other fields, dominating the entire microelectronics packaging materials market. Epoxy resins contain unique epoxy groups, as well as reactive groups such as hydroxyl groups and ether bonds, resulting in numerous excellent properties. They can be combined with a wide range of curing agents, accelerators, and modifiers to create a variety of unique epoxy resin curing systems with superior performance, adapting to and meeting diverse performance and process requirements.

[0003] However, due to the high crosslink density and high internal stress of cured epoxy resin, when used in packaging materials, it suffers from brittleness, poor fatigue resistance, heat resistance, and impact toughness. Therefore, improving the performance of epoxy resin materials has attracted considerable attention. Silicon dioxide, due to its low coefficient of thermal expansion and superior properties such as high heat and humidity resistance, is widely used as a filler in polymer and resin matrices to enhance the performance of resin composites.

[0004] In view of the insufficient toughness of epoxy encapsulation materials when silica is used as a filler, this project will prepare surface-grafted epoxy resin, toughen and modify the silica material, and then use it as a filler to prepare high-performance epoxy resin composite encapsulation materials. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an epoxy molding compound of modified silica grafted with epoxy resin, which is used to improve the toughness of silica, so that it can be used as a filler in epoxy molding compound to improve the performance of composite materials of electronic packaging materials.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention provides a method for surface modification of silicon dioxide, comprising the following steps:

[0008] 1) Preparation of modified prepolymer:

[0009] Stirring polyethylene glycol and diisocyanate to react under the action of a catalyst until the isocyanate concentration in the polymerization reaction system drops to 40-60% of the initial concentration;

[0010] 2) Surface modification:

[0011] The silicon dioxide and the prepolymer obtained in step 1) are stirred and reacted in a solvent.

[0012] As a preferred embodiment, in step 1), the stirring reaction temperature is 15 to 55°C, for example, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or any temperature therebetween;

[0013] Preferably, the catalyst is selected from dibutyltin dilaurate or dibutyltin didodecylsulfide;

[0014] Preferably, the diisocyanate is selected from toluene diisocyanate or diphenylmethane diisocyanate;

[0015] Preferably, the polyethylene glycol is a polyethylene glycol with a molecular weight of 400 to 800;

[0016] Preferably, in step 1), the mass ratio of the diisocyanate to the polyethylene glycol is 1.5 to 2.5:1, for example, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1 or any mass ratio therebetween;

[0017] Preferably, the mass of the catalyst is 0.05-0.5% of the total mass of the polyethylene glycol and the diisocyanate, for example, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5% or any mass percentage therebetween;

[0018] Preferably, step 1) is carried out in an inert gas;

[0019] As a preferred embodiment, in step 2), the stirring reaction speed is 1000-1500 r / min, for example, 1000 r / min, 1100 r / min, 1200 r / min, 1300 r / min, 1400 r / min, 1500 r / min or any speed therebetween; the stirring reaction temperature is 70-90°C, for example, 70°C, 75°C, 80°C, 85°C, 90°C or any temperature therebetween; the stirring reaction time is 6-10 h;

[0020] Preferably, in step 2), the solvent is selected from toluene or toluene-cyclohexanone;

[0021] Preferably, in step 2), the mass ratio of the silicon dioxide to the prepolymer is 1:1 to 3, for example, 1:1, 1:2, 1:3 or any mass ratio therebetween;

[0022] Preferably, step 2) is carried out in an inert gas;

[0023] Silica nanoparticles readily absorb water and typically have silanol groups on their surface. In the technical solution of the present invention, the reaction between the prepolymer and silica primarily involves the silanol groups on the silica surface reacting with the flexible chains of the polyethylene glycol prepolymer containing isocyanate groups, resulting in the flexible chains being grafted onto the silica surface.

[0024] The second aspect of the present invention provides modified silica obtained by the above method.

[0025] A third aspect of the present invention provides a method for grafting modified silica onto epoxy resin, comprising the following steps:

[0026] The modified silica and epoxy resin are dispersed in a solvent, dimethylamine gas is introduced, and the mixture is stirred for reaction.

[0027] As a preferred embodiment, the mass ratio of the modified silica to the epoxy resin is 0.35 to 1.5:1, for example, 0.35:1, 0.40:1, 0.45:1, 0.50:1, 0.55:1, 0.65:1, 0.75:1, 0.85:1, 0.95:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1 or any ratio therebetween.

[0028] Preferably, the solvent is a mixed solvent of ethylene glycol butyl ether and anhydrous ethanol, and the volume ratio is preferably 1.8 to 2.2:1;

[0029] Preferably, the stirring reaction speed is 200-400 r / min, the stirring reaction temperature is 50-70° C., and the stirring reaction time is 2-4 hours;

[0030] Preferably, the preparation method further comprises a post-processing operation, and the post-processing operation comprises filtration, washing and drying.

[0031] A fourth aspect of the present invention provides an epoxy molding compound of modified silica grafted onto epoxy resin, the epoxy molding compound comprising:

[0032] (A) Epoxy resin;

[0033] (B) phenolic resin;

[0034] (C) inorganic fillers;

[0035] (D) a silane coupling agent;

[0036] (E) a release agent;

[0037] (F) a curing accelerator;

[0038] (G) flame retardants;

[0039] (H) Fumed silicon;

[0040] (I) colorant;

[0041] Wherein, the inorganic filler (C) is the modified silica, or a mixture of the modified silica and unmodified silica; the content of the inorganic filler (C) is 60 to 95 wt % of the total epoxy molding compound.

[0042] In the technical solution of the present invention, the average particle size of the unmodified silicon dioxide is 5 to 8 μm, and the modified silicon dioxide is prepared by modifying the unmodified silicon dioxide with an average particle size of 5 to 8 μm through the above method.

[0043] As a preferred embodiment, the content of each component of the epoxy molding compound is:

[0044] The content of the epoxy resin (A) is 10-40 wt % of the total epoxy molding compound.

[0045] The content of the phenolic resin (B) is 2% to 6wt% of the total epoxy molding compound;

[0046] The (D) silane coupling agent is 0.05 to 5 wt% of the (C) inorganic filler;

[0047] The (E) release agent is 0.005-2wt% of the total epoxy molding compound, preferably 0.1-2.5wt%;

[0048] The (F) curing accelerator is 0.005-2 wt% of the total epoxy molding compound, preferably 0.01-0.5 wt%;

[0049] The flame retardant (G) is 0.2-0.5 wt% of the total epoxy molding compound;

[0050] The (H) fumed silicon is 0.2-0.5 wt% of the total epoxy molding compound;

[0051] The colorant (I) is 0.05-0.3 wt% of the total epoxy molding compound;

[0052] Preferably, when the inorganic filler is a mixture of the modified silica and unmodified silica, the mass ratio of the modified silica to the unmodified silica is 0.15 to 20:1.

[0053] In some specific embodiments, the mass ratio of the modified silica to the unmodified silica is 0.15:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1 or any mass ratio therebetween.

[0054] In certain specific embodiments, the epoxy resin as component (A) is a commonly used encapsulation epoxy resin, and is not particularly limited. Examples thereof include (1) glycidyl ether epoxy resins such as diglycidyl ethers of bisphenol A, bisphenol F, bisphenol S, cresol, xylenol, resorcinol, catechol, alkyl-substituted or non-substituted diphenols, etc.; (2) phenolic epoxy resins obtained by self-condensation or co-condensation of aldehyde-containing compounds such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde, and salicylaldehyde under an acidic catalyst; (3) epoxy resins containing sulfur atoms, hydroquinone epoxy resins, phthalic acid, dimer acid, etc., obtained by reacting polyacids with epichlorohydrin; Glycerol ester type epoxy resin; (4) Glycidylamine type epoxy resin obtained by reacting polyamines such as diaminodiphenylmethane and isocyanic acid with epichlorohydrin; (5) Epoxides of dicyclopentadiene and phenol and / or naphthol co-condensation resins; (6) Epoxy resins containing naphthalene rings; (7) Epoxides of aralkyl type phenol resins such as phenol·aralkyl resins and naphthol·aralkyl resins; (8) Trimethylolpropane type epoxy resins; (9) Ester ring epoxy resins, etc. These can be used alone or in combination of two or more.

[0055] Due to the convenient source of raw materials and low cost, preferably, bisphenol A type epoxy resin is used, and more preferably, an epoxy resin represented by the general formula (1) is used.

[0056]

[0057] In formula (I), n is the degree of polymerization, which is an integer from 0 to 3;

[0058] In the general formula (I), the hydrogen atoms on C1 to C6 may be replaced by substituents, which may be substituted or unsubstituted monovalent hydrocarbon groups, which may be saturated or unsaturated; in addition, the substituted or unsubstituted monovalent hydrocarbon groups may be linear, branched or cyclic, but are particularly preferably methyl or ethyl.

[0059] In the technical solution of the present invention, the phenolic resin (B) serves as a curing agent for the epoxy resin (A), and refers to monomers, oligomers, and polymers having two or more phenolic hydroxyl groups. Examples thereof include neophenolic phenolic resins represented by formula (II), cresol novolac epoxy resins, aromatic alkyl phenolic resins, trisphenol methane phenolic resins represented by formula (III), naphthol novolac resins, aromatic alkyl phenolic resins, and biphenyl novolac resins. The above phenolic resins can be used alone or in any combination.

[0060] In order to protect the semiconductor chip from moisture, preferably, a low hygroscopic phenolic resin such as a neophenol type phenolic resin represented by formula (II) and a trisphenol methane type phenolic resin represented by formula (III) is used.

[0061]

[0062] In a preferred embodiment, the equivalent ratio of the epoxy resin (A) to the phenolic resin (B), i.e., the ratio of the number of epoxy groups in the epoxy resin to the number of hydroxyl groups in the phenolic resin, is not particularly limited. To improve the conversion rate of reactants and control the reaction rate, this ratio is preferably set in the range of 0.5 to 2, more preferably in the range of 0.6 to 1.3. To obtain an epoxy resin molding compound for encapsulation with excellent moldability and reflow resistance, it is more preferably set in the range of 0.8 to 1.0.

[0063] In certain specific embodiments, the silane coupling agent (D) has a structure represented by the following general formula (IV):

[0064]

[0065] In formula (II), m is an integer of 1 to 3, n is an integer of 0 to 3, and R 1 Selected from

[0066] Any of

[0067] Among them, (X) j Any one selected from a hydrogen atom and an alkyl group having 1 to 6 carbon atoms; R 2 、R 3 Each independently selected from methyl or ethyl, and in R 2 OR 3 When there are multiple, they may be the same or different;

[0068] Preferably, R 1 for Silane coupling agents, such as γ-anilinopropyltrimethoxysilane, γ-anilinopropyltriethoxysilane, γ-anilinopropylmethyldimethoxysilane, γ-anilinopropylmethyldiethoxysilane, γ-anilinopropylethyldiethoxysilane, and γ-anilinopropylethyldimethoxysilane, are mixed into epoxy molding compounds to improve the adhesion between inorganic fillers and resins, allowing the fillers to better utilize their inherent properties. Specific examples include γ-anilinopropyltrimethoxysilane, γ-anilinopropyltriethoxysilane, γ-anilinopropylmethyldimethoxysilane, γ-anilinopropylmethyldiethoxysilane, γ-anilinopropylethyldiethoxysilane, and γ-anilinopropylethyldimethoxysilane.

[0069] More preferably, the silane coupling agent of component (D) is γ-anilinopropyltrimethoxysilane.

[0070] In certain specific embodiments, the (E) release agent is selected from at least one of (α) a linear saturated carboxylic acid having a number average molecular weight of 550 to 800, and (β) an oxidized polyethylene wax.

[0071] Specifically, the structure of the linear saturated carboxylic acid with a number average molecular weight of 550 to 800 is shown in general formula (V):

[0072]

[0073] Wherein n is 32 to 52, but in practice, an appropriate repeating number n is selected so that the number average molecular weight reaches 550 to 800. Preferably, the number average molecular weight of the linear saturated carboxylic acid is 600 to 800.

[0074] In the technical solution of the present invention, a curing accelerator is further added to improve the curability of the epoxy molding compound. The curing accelerator (F) is present in an amount of 0.005 to 2 wt% of the total epoxy molding compound. If the amount of curing accelerator is less than 0.005%, the curability tends to deteriorate in a short period of time. If the amount exceeds 2%, the curing speed is too fast, making it difficult to obtain a well-shaped molded product. In certain specific embodiments, the (F) curing accelerator is a substance generally used in epoxy resin molding compounds for packaging, and there is no particular limitation thereto. Examples thereof include (1) cyclic amidine compounds: 1,8-diaza-bicyclo[5.4.0]undecene-7, 1,5-diaza-bicyclo[4.3.0]nonene, 5,6-dibutylamino-1,8-diaza-bicyclo[5.4.0]undecene-7, etc.; (2) quinone compounds: on the basis of cyclic amidine compounds, maleic anhydride, 1,4-benzoquinone, 2,5-toluenequinone, 2,3-dimethylbenzene are added. Quinone compounds such as quinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1- quinone; (3) Imidazolinones such as 2-methylimidazoline, 2-phenylimidazoline, 2-phenyl-4-methylimidazoline and their derivatives; (4) Organic phosphines: tributylphosphine, methyldiphenylphosphine, triphenylphosphine, tri(4-methylphenyl)phosphine, diphenylphosphine, phenylphosphine, etc.; (5) Compounds with intramolecular polarity formed by adding maleic anhydride, the above-mentioned quinone compounds, phenylazomethane, phenol resin and the like compounds having π-bonds to the above-mentioned organic phosphine compounds.

[0075] In the technical solution of the present invention, the flame retardant (G) is not particularly limited as long as it is an ester formed by a compound of phosphoric acid and alcohol or a compound of phosphoric acid and phenol. Examples thereof include trimethyl phosphate, triethyl phosphate, triphenyl phosphate, dihydroxycresyl phosphate, and trixylyl phosphate. Among them, aromatic condensed phosphates having the structure represented by general formula (VI) are preferably used due to their hydrolysis resistance.

[0076]

[0077] As a preferred embodiment, the amount of the flame retardant (G) added is preferably 0.2% to 0.5% relative to the total mixed components excluding the filler. If the amount is less than 0.2%, problems such as lead offset and mold cavity may occur. If the amount is greater than 3%, moldability and moisture resistance may be reduced.

[0078] In the technical solution of the present invention, the (H) fumed silicon is the fumed silicon dioxide commonly used in epoxy molding compounds for packaging, and there is no particular limitation. Preferably, the average particle size of the fumed silicon dioxide is in the range of 5 to 40 nm, and the specific surface area is 360 ± 30 m 2 / g, the larger specific surface area and particle size of silica will reduce the toughness of epoxy molding compound.

[0079] A fifth aspect of the present invention provides a method for preparing the above-mentioned epoxy molding compound, comprising the following steps:

[0080] (1) dispersing the surface-modified silica and epoxy resin in a solvent, introducing dimethylamine gas, and stirring to react;

[0081] (2) The mixed system obtained in step (1) is mixed with other components in proportion, and then extruded and kneaded to obtain the epoxy molding compound.

[0082] As a preferred embodiment, in step (1), the mass ratio of the modified silica to the epoxy resin is 0.35 to 1.5:1;

[0083] Preferably, in step (1), the solvent is a mixed solvent of ethylene glycol butyl ether and anhydrous ethanol, and the volume ratio is preferably 1.8 to 2.2:1;

[0084] Preferably, in step (1), the rotation speed of the stirring reaction is 200-400 r / min, the temperature of the stirring reaction is 50-70° C., and the time of the stirring reaction is 2-4 hours;

[0085] Preferably, step (1) further comprises post-processing operations, wherein the post-processing comprises filtration, washing and drying.

[0086] As a preferred embodiment, the temperature of the extrusion mixing in step (2) is 80 to 120°C.

[0087] In the technical solution of the present invention, flexible chain-extended urea is produced by reaction on the surface of silica, and its active end groups participate in the epoxy resin network, thereby improving the bonding performance of the interface between the particle and the resin matrix. At the same time, the flexible part on the particle surface can improve the plastic deformation ability of the matrix around the particle, and local plastic deformation is more likely to occur. All of these can effectively increase the fracture toughness value of the epoxy molding compound, toughen the epoxy resin matrix, and significantly improve the mechanical properties of the epoxy resin composite material. After the modified silica is mixed with the epoxy resin, the modifier is incorporated into the cross-linked network of the epoxy resin through the active end groups of the modified silica, and the flexible chains grafted on the surface of the modified silica filler are capped by dimethylamine, thereby grafting the epoxy resin onto the silica surface.

[0088] The beneficial effect of the present application is that compared with not adding modified silica filler, by using modified silica powder with surface grafted epoxy resin as filler, the epoxy molding compound can achieve high filling while increasing the fracture toughness value of the molding compound, thereby improving the toughness of the molding compound. DETAILED DESCRIPTION

[0089] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0090] The epoxy resins used in the following examples and comparative examples are listed below:

[0091] Bisphenol A type epoxy resin represented by formula (VII) (epoxy equivalent: 192, melting point: 105° C., purchased from Nippon Kayaku Co., Ltd., brand name RE410).

[0092]

[0093] The phenolic resins used in the following examples and comparative examples are listed below:

[0094] Phenolic resin 1: a novel phenolic resin represented by formula (VIII) (hydroxyl equivalent weight: 203, softening point: 110°C, purchased from Kolon Chemical Co., Ltd., brand KPH-F3065)

[0095]

[0096] Phenolic resin 2: trisphenol methane-type phenolic resin represented by formula (IX) (hydroxyl equivalent: 110, softening point: 97° C., purchased from Meiwa Chemicals Co., Ltd., brand MEH-7500).

[0097]

[0098] The unmodified silicon dioxide used in the following examples and comparative examples is silicon dioxide powder having an average particle size of 5 to 8 μm.

[0099] The silane coupling agents used in the following examples and comparative examples are listed as follows: γ-anilinopropyltrimethoxysilane.

[0100] The release agents used in the following examples and comparative examples are listed as follows: CH3-(CH2) n -COOH (n=24 average), Unicid 700 manufactured by Baker Petroleum Company (number average molecular weight: 789).

[0101] The curing accelerator used in the following examples and comparative examples is triphenylphosphine.

[0102] The flame retardant used in the following examples and comparative examples is trimethyl phosphate.

[0103] The fumed silicon used in the following examples and comparative examples is: silicon dioxide with an average particle size of 15 nm and a specific surface area of ​​360 m 2 / g.

[0104] The colorant used in the following examples and comparative examples is: black organic dye.

[0105] Preparation example of modified silica grafted epoxy resin:

[0106] 1. Add 2,4-toluene diisocyanate (TDI) to the reaction apparatus and fill with nitrogen for 15 minutes. Slowly add polyethylene glycol with a molecular weight of 600 at a drop rate of 0.5 mL / min. After the addition is complete, heat to 60°C at a heating rate of 5°C / min at a speed of 1200 r / m and continue heating for 4 hours. Add dibutyltin dilaurate as a reaction catalyst. Titrate the heated sample to detect the isocyanate content in the reaction system; stop heating when the isocyanate concentration drops to half of the initial concentration.

[0107] 2. Disperse the vacuum-dried unmodified silica in anhydrous toluene and ultrasonically disperse for 0.5 hours. Dissolve the aforementioned toluene diisocyanate and polyethylene glycol prepolymer in anhydrous toluene, stir until uniform, and then mix with the ultrasonically treated silica. Under nitrogen, mechanically stir at 80°C and 1200 rpm for 8 hours. Repeatedly wash with anhydrous toluene to remove unreacted polyethylene glycol prepolymer. Vacuum dry the resulting product at 60°C for 12 hours to obtain modified silica powder.

[0108] 3. Mix 10 mL of ethylene glycol butyl ether and 5 mL of anhydrous ethanol, dissolve the modified silica powder and epoxy resin in the mixture, and heat to 60°C. Add dimethylamine gas while stirring at 300 rpm and allow to react for 3 hours. After the reaction, filter the mixture, wash it, and vacuum dry it at 60°C for 12 hours. The product is a white or light yellow powder, resulting in epoxy resin-grafted modified silica.

[0109] Among them, in Examples 1-9, the masses of diisocyanate, polyethylene glycol, and dibutyltin dilaurate in step 1, the amount of unmodified silica used in step 2, and the amount of epoxy resin in step 3 are shown in Table 1.

[0110] Table 1

[0111]

[0112]

[0113] In step 1, the isocyanate concentration is determined as follows: Weigh approximately 1 g of sample into a 100 mL conical flask and add 10 mL of dioxane. Once dissolved, pipette accurately into 10 mL of a 0.5 mol / L solution of n-butylamine in dioxane. After 15 minutes, add 3-5 drops of methyl red solution. Titrate with 0.1 mol / L standard hydrochloric acid solution until the solution turns from yellow to red at the endpoint. Simultaneously perform a blank titration.

[0114] The calculation formula for isocyanate concentration is shown in formula (VIII):

[0115]

[0116] In formula (VIII): C is the percentage of isocyanate in the sample;

[0117] V is the volume of hydrochloric acid standard solution consumed in sample titration (mL);

[0118] V0 is the volume of hydrochloric acid standard solution consumed in the blank titration (mL);

[0119] M is the concentration of the hydrochloric acid standard solution (mol / L);

[0120] W is the weight of the sample (g).

[0121] The modified silica with epoxy resin grafted on the surface was applied in the following examples:

[0122] Example 1

[0123] 94.44 g of modified silica grafted with epoxy resin (including 38.6 g of epoxy resin and 19.3 g of silica), 2.78 g of phenolic resin 1, 1.19 g of phenolic resin 2, 0.28 g of a curing accelerator, 0.41 g of a flame retardant, 0.15 g of a silane coupling agent, 0.25 g of a release agent, 0.3 g of fumed silicon and 0.2 g of a colorant were mixed, kneaded and mixed at an extrusion temperature of 100° C., cooled and finely pulverized to obtain an epoxy molding compound.

[0124] Example 2

[0125] 89.44 g of modified silica grafted with epoxy resin, including 35.6 g of epoxy resin, 17.8 g of silica, 5 g of unmodified silica, 2.78 g of phenolic resin 1, 1.19 g of phenolic resin 2, 0.28 g of a curing accelerator, 0.41 g of a flame retardant, 0.15 g of a silane coupling agent, 0.25 g of a release agent, 0.3 g of fumed silicon and 0.2 g of a colorant, are mixed, kneaded and mixed at an extrusion temperature of 100° C., cooled and finely pulverized to obtain an epoxy molding compound.

[0126] Example 3

[0127] 84.44 g of modified silica grafted with epoxy resin, including 32.6 g of epoxy resin, 16.3 g of silica, 10 g of unmodified silica, 2.78 g of phenolic resin 1, 1.19 g of phenolic resin 2, 0.28 g of a curing accelerator, 0.41 g of a flame retardant, 0.15 g of a silane coupling agent, 0.25 g of a release agent, 0.3 g of fumed silicon and 0.2 g of a colorant, are mixed, kneaded and mixed at an extrusion temperature of 100° C., cooled and finely pulverized to obtain an epoxy molding compound.

[0128] Example 4

[0129] 74.44 g of modified silica grafted with epoxy resin, including 29.6 g of epoxy resin, 14.8 g of silica, 20 g of unmodified silica, 2.78 g of phenolic resin 1, 1.19 g of phenolic resin 2, 0.28 g of curing accelerator, 0.41 g of flame retardant, 0.15 g of silane coupling agent, 0.25 g of release agent, 0.3 g of fumed silicon and 0.2 g of colorant, are mixed, kneaded and mixed at an extrusion temperature of 100° C., cooled and finely pulverized to obtain an epoxy molding compound.

[0130] Example 5

[0131] 64.44 g of modified silica grafted with epoxy resin, including 26.6 g of epoxy resin, 13.3 g of silica, 30 g of unmodified silica, 2.78 g of phenolic resin 1, 1.19 g of phenolic resin 2, 0.28 g of curing accelerator, 0.41 g of flame retardant, 0.15 g of silane coupling agent, 0.25 g of release agent, 0.3 g of fumed silicon and 0.2 g of colorant, are mixed, kneaded and mixed at an extrusion temperature of 100° C., cooled and finely pulverized to obtain an epoxy molding compound.

[0132] Example 6

[0133] 54.44 g of modified silica grafted with epoxy resin, including 23.6 g of epoxy resin, 11.8 g of silica, 40 g of unmodified silica, 2.78 g of phenolic resin 1, 1.19 g of phenolic resin 2, 0.28 g of curing accelerator, 0.41 g of flame retardant, 0.15 g of silane coupling agent, 0.25 g of release agent, 0.3 g of fumed silicon and 0.2 g of colorant, are mixed, kneaded and mixed at an extrusion temperature of 100° C., cooled and finely pulverized to obtain an epoxy molding compound.

[0134] Example 7

[0135] 44.44 g of modified silica grafted with epoxy resin, including 20.6 g of epoxy resin, 10.3 g of silica, 50 g of unmodified silica, 2.78 g of phenolic resin 1, 1.19 g of phenolic resin 2, 0.28 g of curing accelerator, 0.41 g of flame retardant, 0.15 g of silane coupling agent, 0.25 g of release agent, 0.3 g of fumed silicon and 0.2 g of colorant, are mixed, kneaded and mixed at an extrusion temperature of 100° C., cooled and finely pulverized to obtain an epoxy molding compound.

[0136] Example 8

[0137] 34.44 g of modified silica grafted with epoxy resin, including 17.6 g of epoxy resin, 8.8 g of silica, 60 g of unmodified silica, 2.78 g of phenolic resin 1, 1.19 g of phenolic resin 2, 0.28 g of curing accelerator, 0.41 g of flame retardant, 0.15 g of silane coupling agent, 0.25 g of release agent, 0.3 g of fumed silicon and 0.2 g of colorant, are mixed, kneaded and mixed at an extrusion temperature of 100° C., cooled and finely pulverized to obtain an epoxy molding compound.

[0138] Example 9

[0139] 24.44 g of modified silica grafted with epoxy resin, including 14.6 g of epoxy resin, 7.3 g of silica, 80 g of unmodified silica, 2.78 g of phenolic resin 1, 1.19 g of phenolic resin 2, 0.28 g of curing accelerator, 0.41 g of flame retardant, 0.15 g of silane coupling agent, 0.25 g of release agent, 0.3 g of fumed silicon and 0.2 g of colorant, are mixed, kneaded and mixed at an extrusion temperature of 100° C., cooled and finely pulverized to obtain an epoxy molding compound.

[0140] Comparative Example 1

[0141] 94.44 g of unmodified silica, 2.78 g of phenolic resin 1, 1.19 g of phenolic resin 2, 0.28 g of a curing accelerator, 0.41 g of a flame retardant, 0.15 g of a silane coupling agent, 0.25 g of a release agent, 0.3 g of fumed silicon and 0.2 g of a colorant were mixed, kneaded and mixed at an extrusion temperature of 100° C., cooled and finely pulverized to obtain an epoxy molding compound.

[0142] The contents of the components in the above examples, i.e., the performance tests, are shown in Table 2-1 and Table 2-2:

[0143] Table 2-1

[0144]

[0145]

[0146] Table 2-2

[0147]

[0148]

[0149] It can be seen from Table 2-1 and Table 2-2 that compared with Comparative Example 1 in which no modified silica is added, in Example 1-9, the epoxy molding compound to which modified silica is added has better bonding between silica and resin, is less prone to brittle fracture, has increased fracture toughness value, and has improved toughness while keeping other parameters basically unchanged.

[0150] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, is also included in the patent protection scope of the present invention.

Claims

1. An epoxy molding compound of modified silica grafted with epoxy resin, characterized in that: The epoxy molding compound comprises: (A) Epoxy resin; (B) phenolic resin; (C) inorganic fillers; (D) a silane coupling agent; (E) a release agent; (F) a curing accelerator; (G) flame retardants; (H) Fumed silicon; (I) colorant; Wherein, the inorganic filler (C) is modified silica or a mixture of modified silica and unmodified silica; the content of the inorganic filler (C) is 60 to 95 wt% of the total epoxy molding compound; when the inorganic filler is a mixture of the modified silica and unmodified silica, the mass ratio of the modified silica to the unmodified silica is 0.15 to 20:1; The method for modifying silicon dioxide comprises the following steps: 1) Preparation of modified prepolymer: The polyethylene glycol and diisocyanate are stirred and reacted in the presence of a catalyst until the isocyanate concentration in the polymerization reaction system is reduced to 40-60% of the initial concentration; 2) Surface modification: Stirring the silicon dioxide and the prepolymer obtained in step 1) in a solvent for reaction; The preparation method of the epoxy molding compound comprises the following steps: (1) dispersing the modified silica and epoxy resin in a solvent, introducing dimethylamine gas, and stirring to react; (2) The mixed system obtained in step (1) is mixed with other components in proportion, and then extruded and kneaded to obtain the epoxy molding compound.

2. The epoxy molding compound according to claim 1, wherein In step 1), the stirring reaction temperature is 15 to 55°C.

3. The epoxy molding compound according to claim 1, wherein: In step 1), the catalyst is selected from dibutyltin dilaurate or dibutyltin didodecylsulfide.

4. The epoxy molding compound according to claim 1, wherein: In step 1), the diisocyanate is selected from toluene diisocyanate or diphenylmethane diisocyanate.

5. The epoxy molding compound according to claim 1, wherein In step 1), the polyethylene glycol is a polyethylene glycol with a molecular weight of 400 to 800.

6. The epoxy molding compound according to claim 1, wherein In step 1), the mass ratio of the diisocyanate to the polyethylene glycol is 1.5 to 2.5:

1.

7. The epoxy molding compound according to claim 1, wherein In step 1), the mass of the catalyst is 0.05 to 0.5% of the total mass of the polyethylene glycol and the diisocyanate.

8. The epoxy molding compound according to claim 1, wherein: Step 1) is carried out in an inert gas.

9. The epoxy molding compound according to claim 1, wherein In step 2), the stirring reaction speed is 1000-1500 r / min; the stirring reaction temperature is 70-90° C. and the stirring reaction time is 6-10 hours.

10. The epoxy molding compound according to claim 1, wherein: In step 2), the solvent is selected from any one of toluene and toluene-cyclohexanone.

11. The epoxy molding compound according to claim 1, wherein In step 2), the mass ratio of the silicon dioxide to the prepolymer is 1:1 to 3.

12. The epoxy molding compound according to claim 1, wherein: Step 2) is carried out in an inert gas.

13. The epoxy molding compound according to claim 1, wherein In step (1), the mass ratio of modified silica to epoxy resin is 0.35 to 1.5:

1.

14. The epoxy molding compound according to claim 1, wherein: In step (1), the solvent is a mixed solvent of ethylene glycol butyl ether and anhydrous ethanol.

15. The epoxy molding compound according to claim 14, wherein In step (1), the solvent is a mixed solvent of ethylene glycol butyl ether and anhydrous ethanol in a volume ratio of 1.8 to 2.2:

1.

16. The epoxy molding compound according to claim 1, wherein In step (1), the stirring reaction is carried out at a speed of 200 to 400 r / min, a temperature of 50 to 70° C., and a time of 2 to 4 hours.

17. The epoxy molding compound according to claim 1, wherein: Step (1) also includes post-processing operations, which include filtration, washing and drying.

18. The epoxy molding compound according to claim 1, wherein: The content of each component of the epoxy molding compound is: The content of the epoxy resin (A) is 10 to 40 wt% of the total epoxy molding compound; The content of the phenolic resin (B) is 2% to 6% by weight of the total epoxy molding compound; The (D) silane coupling agent is 0.05 to 5 wt% of the (C) inorganic filler; The (E) release agent is 0.005 to 2 wt% of the total epoxy molding compound; The (F) curing accelerator is 0.005 to 2 wt% of the total epoxy molding compound; The flame retardant (G) is 0.2 to 0.5 wt% of the total epoxy molding compound; The (H) fumed silicon is 0.2% to 0.5 wt% of the total epoxy molding compound; The colorant (I) is 0.05 to 0.3 wt% of the total epoxy molding compound.

19. The epoxy molding compound according to claim 18, wherein The (E) release agent is 0.1 to 2 wt% of the total epoxy molding compound.

20. The epoxy molding compound according to claim 18, wherein The (F) curing accelerator is 0.01 to 0.5 wt% of the total epoxy molding compound.

21. The epoxy molding compound according to claim 1, wherein The extrusion mixing temperature in step (2) is 80 ~ 120 ° C.

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