1. A preparation method of an epoxy resin potting material is characterized by comprising the following steps: the method comprises the following steps:

(1) preparing a multi-scale one-dimensional reinforcement: placing 10-30 parts by mass of fibers in 605-970 parts by mass of reversed-phase microemulsion containing alkali metal silicate, then using hydrochloric acid for precipitation, performing in-situ growth to generate nano-scale silicon dioxide on the surfaces of the fibers, and cleaning and drying to obtain the multi-scale one-dimensional reinforcement; the reverse microemulsion containing the alkali metal silicate comprises the following components in percentage by mass: an aqueous alkali metal silicate solution comprising a hydrocarbon, an alcohol, and a surfactant, wherein the surfactant comprises 500 to 750 parts by weight of (50 to 90 parts by weight of) (50 to 100 parts by weight of (5 to 30 parts by weight of) the aqueous alkali metal silicate solution;

(2) preparing the components of the potting material: ultrasonically dispersing the multi-scale one-dimensional reinforcement prepared in the step (1) and epoxy resin, and then uniformly dispersing to prepare a component A of the potting material, wherein the epoxy resin and the multi-scale composite reinforcement comprise the following components in parts by weight: (50-100) 20-50; uniformly stirring a curing agent, an accelerator and a zero-dimensional inorganic filler at a high speed to prepare a component B of the potting material, wherein the ratio of the curing agent to the accelerator to the zero-dimensional inorganic filler is (50-90) to (2-6) to (80-120);

(3) preparing a potting material: and (2) mixing the component A and the component B according to the weight part ratio of 1 (1-2), and uniformly stirring to obtain the epoxy resin-based encapsulating material.

2. The preparation method of the epoxy resin potting compound according to claim 1, wherein in the step (1), the fiber is one or more of basalt fiber, glass fiber and aramid fiber.

3. The method for preparing epoxy resin potting compound according to claim 1, wherein in the step (1), the alkali metal silicate is sodium silicate, potassium silicate or a mixture thereof.

4. The preparation method of the epoxy resin potting compound according to claim 3, wherein in the step (1), the content of silica in the alkali metal silicate is 25-45%, and the modulus is 1-3.

5. The method for preparing the epoxy resin potting compound according to claim 1, wherein in the step (1), the hydrocarbon is one of vegetable oil or animal oil or a mixed combination thereof, and the alcohol is one or more of ethanol, propanol and butanol.

6. The method for preparing the epoxy resin potting compound according to claim 1, wherein in the step (1), the surfactant is one or more of monolauryl phosphate, lauryl alcohol ether phosphate, coco diethanol amide and cocamidopropyl dimethyl amine ethyl lactone.

7. The method for preparing the epoxy resin potting compound according to claim 1, wherein in the step (2), the epoxy resin is one or more of bisphenol A type glycidyl ether, glycidyl ester type glycidyl ether, polyphenol type glycidyl ether and aliphatic glycidyl ether.

8. The method for preparing an epoxy resin potting material as claimed in claim 1, wherein in the step (2), the curing agent is methyltetrahydrophthalic anhydride, liquid methylhexahydrophthalic anhydride, hexahydrophthalic anhydride or methylnadic anhydride.

9. The method for preparing the epoxy resin potting compound according to claim 1, wherein in the step (2), the accelerator is N, N-dimethyl-1, 3-propanediamine, 2-methylimidazole or 2-ethyl-4-methylimidazole.

10. The preparation method of the epoxy resin potting material according to claim 1, wherein in the step (2), the zero-dimensional inorganic filler is one or more of silicon carbide, silicon micropowder, calcium carbonate and aluminum oxide, and the particle size range of the zero-dimensional inorganic filler is 10-70 μm.

Background

The epoxy resin potting material is widely applied to strengthening of electronic component structures due to excellent mechanical property, thermal property and electrical insulation property, so that the insulativity between internal elements and circuits is increased, and the resistance to external impact and vibration is improved, thereby achieving the purposes of insulation protection, water resistance, moisture resistance and the like. The highly crosslinked epoxy resin is brittle and has poor toughness, and needs to be reinforced and toughened to meet the actual use requirement. The reinforcing and toughening of epoxy resin by using fibers and inorganic particles is the mainstream method at present, and the performance reduction of the potting material caused by the compatibility between the fibers, the inorganic particles and the epoxy resin and the agglomeration and sedimentation among fillers becomes a problem to be solved urgently.

Surface modification of fillers has been the mainstream method for improving the compatibility between the filler and the matrix resin. The Chinese patent application with publication number CN107841091A discloses a preparation method of a tough epoxy potting material, which is characterized in that nano calcium carbonate is embedded in the surface of basalt fiber, calcium carbonate is removed after high-temperature treatment to leave grooves on the surface of the basalt fiber, then perlite material is used for ball milling and filling the grooves on the surface of the basalt fiber, anchoring fiber with large specific surface area is obtained after high-temperature treatment, a cross-linked structure is formed in resin, and the toughness of the epoxy potting material is improved. However, the modification method has high modification temperature, and the improvement of toughness reduces the tensile strength to a certain extent.

The Chinese patent application with the publication number of CN104231993A discloses a preparation method of a modified inorganic nanoparticle toughened epoxy resin pouring sealant, and the polyaniline modification of inorganic nanoparticles is used for improving the compatibility of the inorganic nanoparticles and matrix resin, so as to achieve the purpose of toughening. And only nanoparticles are used for single-scale toughening, so that the mechanical strength of the potting material is reduced due to the limitation of the material.

Disclosure of Invention

The invention aims to solve the technical problem of low strength of the existing potting material, and provides a preparation method of a low-viscosity high-strength high-compression-resistance epoxy resin potting material.

Therefore, the invention provides a preparation method of an epoxy resin potting material, which comprises the following steps: (1) preparing a multi-scale one-dimensional reinforcement: placing 10-30 parts by mass of fibers in 605-970 parts by mass of reversed-phase microemulsion containing alkali metal silicate, then using hydrochloric acid for precipitation, performing in-situ growth to generate nano-scale silicon dioxide on the surfaces of the fibers, and cleaning and drying to obtain the multi-scale one-dimensional reinforcement; the reverse microemulsion containing the alkali metal silicate comprises the following components in percentage by mass: an aqueous alkali metal silicate solution comprising a hydrocarbon, an alcohol, and a surfactant, wherein the surfactant comprises 500 to 750 parts by weight of (50 to 90 parts by weight of) (50 to 100 parts by weight of (5 to 30 parts by weight of) the aqueous alkali metal silicate solution; (2) preparing the components of the potting material: ultrasonically dispersing the multi-scale one-dimensional reinforcement prepared in the step (1) and epoxy resin, and then uniformly dispersing to prepare a component A of the potting material, wherein the epoxy resin and the multi-scale composite reinforcement comprise the following components in parts by weight: (50-100) 20-50; uniformly stirring a curing agent, an accelerator and a zero-dimensional inorganic filler at a high speed to prepare a component B of the potting material, wherein the ratio of the curing agent to the accelerator to the zero-dimensional inorganic filler is (50-90) to (2-6) to (80-120); (3) preparing a potting material: and (3) mixing the component A and the component B according to the weight part ratio of 1 (1-2), and uniformly stirring at a high speed of 600rpm at the room temperature of 400-.

Preferably, in the step (1), the fiber is one or more of basalt fiber, glass fiber and aramid fiber.

Preferably, in the step (1), the alkali metal silicate is sodium silicate, potassium silicate or a mixture thereof.

Preferably, in the step (1), the content of silicon dioxide in the alkali metal silicate is 25% -45%, and the modulus is 1-3.

Preferably, in the step (1), the hydrocarbon is one of vegetable oil or animal oil or a mixed combination thereof, and the alcohol is one or more of ethanol, propanol and butanol.

Preferably, in the step (1), the surfactant is one or more of monolauryl phosphate, lauryl alcohol ether phosphate, coco diethanol amide and coco amidopropyl dimethyl amine ethyl lactone.

Preferably, in the step (2), the epoxy resin is one or more of bisphenol a type glycidyl ether, glycidyl ester type glycidyl ether, polyphenol type glycidyl ether and aliphatic glycidyl ether.

Preferably, in the step (2), the curing agent is methyltetrahydrophthalic anhydride, liquid methylhexahydrophthalic anhydride, hexahydrophthalic anhydride or methylnadic anhydride.

Preferably, in the step (2), the accelerator is N, N-dimethyl-1, 3-propanediamine, 2-methylimidazole or 2-ethyl-4-methylimidazole.

Preferably, in the step (2), the zero-dimensional inorganic filler is one or more of silicon carbide, silicon micropowder, calcium carbonate and alumina, and the particle size range of the zero-dimensional inorganic filler is 10-70 μm.

The invention has the following beneficial effects:

the invention utilizes reverse microemulsion to prepare reinforcing fiber loaded with nano silicon dioxide, namely a multi-scale one-dimensional reinforcement, and simultaneously adopts zero-dimensional inorganic filler for reinforcing the multi-scale reinforced potting material, in particular to:

1. the invention adopts a 'reverse microemulsion' method to grow nano-silicon dioxide on the surface of the fiber in situ to prepare the multi-scale one-dimensional reinforcement, so that the distribution of the nano-silicon dioxide in the epoxy resin is more uniform along with the distribution of the fiber, and the agglomeration of the filler is reduced.

2. The invention uses the multi-scale one-dimensional reinforcement and the zero-dimensional inorganic filler to compound and reinforce the epoxy resin, constructs a multi-dimensional multi-scale reinforcement system and leads the viscosity to be lower.

3. Due to the synergistic effect of multi-scale enhancement, the mechanical property and the molding shrinkage rate of the encapsulating material are improved.

Detailed Description

The present invention will be further described with reference to the following examples.

In each embodiment, the tensile strength and the compressive strength of the composite material are obtained by testing through an Instron-1121 universal material testing machine, and the compressive strength test standard is GB/T1041-2008; the tensile strength test standard is GB/T1040-.

Example 1

Preparing a multi-scale one-dimensional reinforcement: adding 750g of sodium silicate aqueous solution (modulus is 2) into a mixture of 70g of vegetable oil, 65g of butanol and 20g of coconut diethanolamide, adding 10g of 1mm glass fiber after mixing completely, then adding hydrochloric acid until no precipitate is generated, taking out the fiber, and drying at 160 ℃ for 4 hours to obtain the one-dimensional multi-scale reinforcement.

Preparing the components of the potting material: 40 parts of multi-scale one-dimensional reinforcement prepared according to the formula and 70 parts of glycidyl ester type epoxy resin TDE85 are weighed, ultrasonically dispersed, and then uniformly dispersed through a three-roll mixing mill to prepare the component A. 60 parts of methyl nadic anhydride curing agent, 2 parts of imidazole accelerator and 100 parts of 10-micron silicon micropowder particles are stirred and dispersed at the rotating speed of 500rpm to prepare a component B.

Preparing a potting material: a, B components are mixed according to the weight portion ratio of 1:1.8 under the high-speed stirring of room temperature and 400rpm to obtain the high-strength low-viscosity high-compression-resistance epoxy resin-based encapsulating material.

Example 2

Preparing a multi-scale one-dimensional reinforcement: adding 500g of sodium silicate aqueous solution (modulus is 1) into a mixture of 50g of vegetable oil, 50g of ethanol and 30g of cocamidopropyl dimethylamine ethyl lactone, adding 20g of 2mm basalt fiber after completely mixing, then adding hydrochloric acid until no precipitate is generated, taking out the fiber, and drying for 3h at 150 ℃ to obtain the one-dimensional multi-scale reinforcement.

Preparing the components of the potting material: weighing 20 parts of the multi-scale one-dimensional reinforcement prepared according to the formula and 50 parts of bisphenol A type glycidyl ether E44, firstly carrying out ultrasonic dispersion, and then uniformly dispersing through a three-roll mixing mill to obtain a component A. 90 parts of methyltetrahydrophthalic anhydride curing agent, 6 parts of N, N-dimethyl-1, 3-propane diamine accelerator and 120 parts of 10 mu m calcium carbonate particles are stirred and dispersed at the rotating speed of 500rpm to prepare a component B.

Preparing a potting material: a, B components are mixed according to the weight portion ratio of 1:2 under the high-speed stirring of 500rpm at room temperature to obtain the high-strength low-viscosity high-compression-resistance epoxy resin-based encapsulating material.

Example 3

Preparing a multi-scale one-dimensional reinforcement: adding 600g of sodium silicate aqueous solution (modulus is 3) into a mixture of 55g of vegetable oil, 100g of propanol and 6g of monolauryl phosphate, adding 30g of 3mm aramid fiber after completely mixing, then adding hydrochloric acid until no precipitate is generated, taking out the fiber, and drying for 4 hours at 200 ℃ to obtain the one-dimensional multi-scale composite reinforcement.

Preparing the components of the potting material: 50 parts of multi-scale one-dimensional reinforcement prepared according to the formula and 100 parts of aliphatic glycidyl ether type epoxy resin dodecyl glycidyl ether are weighed, firstly ultrasonically dispersed, and then uniformly dispersed through a three-roll mixing mill to prepare the component A. 50 parts of hexahydrophthalic anhydride curing agent, 4 parts of 2-ethyl-4-methylimidazole accelerator and 80 parts of 70-micron silicon carbide particles are stirred and dispersed at the rotating speed of 500rpm to prepare a component B.

Preparing a potting material: a, B components are mixed according to the weight portion ratio of 1:1 at the room temperature of 600rpm under high-speed stirring to obtain the high-strength low-viscosity high-compression-resistance epoxy resin-based encapsulating material.

Comparative example 1

The difference between the comparative example 1 and the example 1 is that the preparation of the pouring sealant is carried out by directly adopting the glass fiber with the length of 1 mm.

Comparative example 2

The difference between the comparative example 2 and the example 1 is that only the polyaniline-modified silica powder is used for preparing the pouring sealant.

TABLE 1 Property parameters of the finished articles of examples 1-4 and comparative examples 1-2

However, the above description is only exemplary of the present invention, and the scope of the present invention should not be limited thereby, and the replacement of the equivalent components or the equivalent changes and modifications made according to the protection scope of the present invention should be covered by the claims of the present invention.