CN113416510B - Epoxy resin pouring sealant and preparation method thereof - Google Patents

Abstract

The application relates to the field of high-performance sealing materials, and particularly discloses an epoxy resin pouring sealant and a preparation method thereof; the pouring sealant is prepared from the following raw materials in parts by weight: 90-110 parts of epoxy resin, 15-25 parts of curing agent, 2-8 parts of nano composite fiber, 5-12 parts of nano particles and 5-12 parts of compatilizer; the preparation method comprises the following steps: weighing epoxy resin, curing agent, nano composite fiber and nano particles, mixing and stirring, adding compatilizer, continuously mixing and stirring to prepare a finished pouring sealant; the curing device has the advantages of being convenient to control the heating uniformity and reducing bubbles generated in the curing process.

Description

Epoxy resin pouring sealant and preparation method thereof

Technical Field

The application relates to the field of high-performance sealing materials, in particular to an epoxy resin pouring sealant and a preparation method thereof.

Background

The epoxy resin pouring sealant can be cured at room temperature or under heating, has high hardness of cured substances, smooth surface, good gloss, and the performances of fixation, insulation, water resistance, oil resistance, dust prevention, anti-theft, corrosion resistance, aging resistance, cold and heat shock resistance and the like, and is used for packaging electronic transformers, AC capacitors, anion generators, aquarium water pumps, ignition coils, electronic modules, LED modules and the like.

After the epoxy resin pouring sealant is poured in winter, the epoxy resin pouring sealant is not easy to cure due to the fact that the temperature is low and the viscosity of the epoxy resin pouring sealant is high; therefore, the curing efficiency is generally improved by heating and curing, and in the heating process, because the heating time and the uniform heating degree are not easy to control, the local reaction of the epoxy resin pouring sealant is easy to be faster, so that bubbles are easy to generate, and the property of the epoxy resin pouring sealant is influenced.

Therefore, the epoxy resin potting adhesive is urgently needed to be provided, the heating uniformity is convenient to control in the heating and curing process, the probability of bubble generation in the curing process is reduced, and the property of the epoxy resin potting adhesive after curing is ensured.

Disclosure of Invention

In order to control the heating uniformity and reduce the probability of generating bubbles in the curing process in the heating curing process, the application provides the epoxy resin pouring sealant and the preparation method thereof.

In a first aspect, the present application provides an epoxy resin potting adhesive, which adopts the following technical scheme:

the epoxy resin pouring sealant is prepared from the following raw materials in parts by weight: 90-110 parts of epoxy resin, 15-25 parts of curing agent, 2-8 parts of nano composite fiber, 5-12 parts of nano particles and 5-12 parts of compatilizer.

By adopting the technical scheme, the nano composite fiber and the nano particles are matched, heat can be transferred through the surface of the nano composite fiber in the heating and curing process, and the heat is uniformly distributed by matching with the transfer effect of the nano particles, so that the heating degree is convenient to control, and the generation of bubbles is reduced; and the nano composite fibers and the nano particles can promote the bubbles to move in the potting adhesive, and the bubbles can move towards the curing surface rapidly by matching with the uniform heating of the potting adhesive, so that the bubbles in the potting adhesive in the curing process are broken, and the properties of the epoxy resin potting adhesive after curing are ensured.

Preferably, the nano composite fiber consists of nano carbon fiber and nano silicon dioxide fiber in a weight ratio of 1: 0.8-1.4.

By adopting the technical scheme, the nano carbon fibers and the nano silicon dioxide fibers are matched, the good heat conduction effect of the nano carbon fibers is matched with the good compatibility of the nano silicon dioxide fibers and the epoxy resin, so that the nano composite fibers are stably dispersed in the pouring sealant to form a network structure, the temperature rise uniformity is controlled by the good heat conduction effect of the network fiber structure, and the condition that bubbles are generated due to uneven temperature rise is reduced.

The nano carbon fiber and the nano silicon dioxide fiber have good strength and good thermal stability, and can prevent bubbles generated by thermal expansion in the curing process of the potting adhesive through the good tensile strength of the nano carbon fiber and the nano silicon dioxide fiber, so that the generation of cracks in the curing process of the potting adhesive is avoided, and the mechanical strength of the potting adhesive is ensured.

Preferably, the nano composite fiber is prepared by the following method:

weighing carbon nanofibers, nano-silica fibers and polyethylene glycol according to the weight ratio of 1:0.8-1.4:0.3-0.8, spraying polyethylene glycol on the surfaces of the carbon nanofibers, immediately adding the nano-silica fibers into the carbon nanofibers sprayed with polyethylene glycol within 30-90s, stirring in the adding process, and drying to obtain the nano-composite fibers.

By adopting the technical scheme, after polyethylene glycol is attached to the surface of the nano carbon fiber, the nano carbon fiber is immediately mixed with the nano silicon dioxide fiber, so that the nano silicon dioxide fiber is stably bonded to the surface of the nano carbon fiber, and the nano carbon fiber and the nano silicon dioxide fiber form a staggered bonded nano composite fiber structure; the nano carbon fibers and the nano silicon dioxide fibers in the pouring sealant are connected to form a network structure, uniform heat conduction is realized in the network structure by utilizing the heat conduction performance of the nano carbon fibers, the temperature uniform distribution condition in the curing process of the pouring sealant is convenient to control, the nano silicon dioxide fibers in the network structure form a relatively tight connection structure with the epoxy resin under the matching of the compatilizer, the bonding effect of the nano carbon fibers and the epoxy resin is indirectly improved, the nano carbon fibers are stably bonded in the pouring sealant, the generation of bubbles in the pouring sealant is reduced, and the properties of the epoxy resin pouring sealant after curing are ensured.

When the epoxy resin pouring sealant is cured, epoxy groups and hydroxyl groups in the epoxy resin react with free hydrogen in the curing agent, the polyethylene glycol in the nano composite fiber contains hydroxyl groups, and the nano composite fiber, the epoxy resin and the curing agent are matched and crosslinked to form a three-dimensional network structure, so that the bonding performance of the nano composite fiber and the epoxy resin is improved, the generation of bubbles in the curing process of the pouring sealant is reduced, and the mechanical strength of the pouring sealant is improved.

The nano composite fibers in the three-dimensional network structure can promote the movement of bubbles in the pouring sealant, and the bubbles in the pouring sealant move towards the surface in a speed-up manner by means of heating, so that the bubbles in the pouring sealant are broken up in a speed-up manner.

Preferably, the nano particles consist of modified nano silicon dioxide and modified nano boron nitride in a weight ratio of 1: 1-3.

By adopting the technical scheme, the modified nano silicon dioxide and the modified nano boron nitride are matched, can be attached to the surface of the nano composite fiber and are in contact with a network structure formed by the nano composite fiber, and the modified nano silicon dioxide is well bonded with the epoxy resin under the matching action of the compatilizer, so that bubbles in the curing process are promoted to move towards the surface in the pouring sealant.

The two-dimensional layered structure of the nano boron nitride is matched with the three-dimensional network structure of the nano composite fiber, the nano boron nitride and the nano composite fiber are stacked in a staggered mode by means of intermolecular force between the nano boron nitride and the nano composite fiber, the heat conduction effect of the nano composite fiber is improved by means of the good heat conduction effect of the nano boron nitride, the internal temperature of the pouring sealant is uniformly distributed, and bubbles are reduced in the curing process of the pouring sealant.

After the bubbles in the pouring sealant are contacted with the nano composite fibers, the bubble breaking is accelerated by utilizing the good releasing effect of the nano composite fibers and the influence of polyethylene glycol on the surface tension of the bubbles, space pores generated in the pouring sealant after the bubbles are broken are quickly filled with epoxy resin, and a three-dimensional network structure formed by the epoxy resin, a curing agent and the nano composite fibers is more compact along with the curing, so that the bubbles are eliminated, and the mechanical strength of the pouring sealant is improved.

Preferably, the modified nano-silica is prepared by the following method:

and (2) spraying hydroxyl silicone oil on the surface of the nano silicon dioxide, wherein the weight ratio of the nano silicon dioxide to the hydroxyl silicone oil is 1:0.1-0.4, drying, and grinding until the particle size is 40-100nm to obtain the modified nano silicon dioxide.

By adopting the technical scheme, the bubbles in the pouring sealant are accelerated to be broken by utilizing the good hydrophobic effect of the hydroxyl silicone oil, and the hydrophobic effect can prevent the pouring sealant from absorbing water in the environment, so that the bubbles in the pouring sealant are reduced.

Hydroxyl silicone oil makes nanometer silica particle surface adhere to there is hydroxyl to nanometer silica's modification, hydroxyl and epoxy, the curing agent cooperatees, can promote epoxy later stage solidification, under the inside bubble-free prerequisite in guaranteeing the embedding glue solidification process, accelerate the later stage solidification rate of embedding glue, cooperation nanometer composite fiber is more even heat conduction effect when improving curing efficiency, make the curing process homogeneous, reduce embedding glue surface cure and the not solidified condition of depths takes place, guarantee the solidification properties of embedding glue when wholly improving embedding glue solidification efficiency.

Preferably, the modified nano boron nitride is prepared by the following method:

spraying hydroxyl silicone oil on the surface of the nano boron nitride, wherein the weight ratio of the nano boron nitride to the hydroxyl silicone oil is 1:0.1-0.3, drying, and grinding until the particle size is 40-100nm to obtain the modified nano boron nitride.

By adopting the technical scheme, after the hydroxyl silicone oil is sprayed on the surface of the nano boron nitride, the bonding effect between the nano boron nitride and the epoxy resin is better, the compatibility of the nano boron nitride and the pouring sealant is improved, and simultaneously, the generation of bubbles in the pouring sealant is inhibited by matching the better heat conduction effect of the nano boron nitride, and the pouring sealant is uniformly cured.

Preferably, the compatibilizing agent is a silane coupling agent.

By adopting the technical scheme, the nano silicon dioxide fiber, the nano silicon dioxide and the epoxy resin are connected by utilizing the silane coupling agent, so that the compatibility of the nano composite fiber, the nano particles and the epoxy resin is improved, and the probability of crack generation in the pouring sealant is reduced.

In a second aspect, the present application provides a method for preparing an epoxy resin potting adhesive, which adopts the following technical scheme: a preparation method of epoxy resin pouring sealant comprises the following steps:

weighing epoxy resin, curing agent, nano composite fiber and nano particles, mixing and stirring, adding compatilizer, continuously mixing and stirring to obtain the finished pouring sealant.

By adopting the technical scheme, the epoxy resin pouring sealant is prepared, the heating uniformity can be conveniently controlled in the heating and curing process, the generation of bubbles in the curing process is reduced, and the bubbles are fundamentally inhibited, so that the mechanical property and the bonding strength of the pouring sealant are ensured.

Preferably, the stirring speed is 350-1000 r/min.

By adopting the technical scheme, the raw materials are uniformly mixed, and the epoxy resin, the nano composite fiber and the nano particles are promoted to form a network structure, so that the curing effect of the pouring sealant is ensured.

In summary, the present application has the following beneficial effects:

1. the nano carbon fiber and the nano boron nitride are matched, and the good heat conducting property of the nano carbon fiber and the nano boron nitride is utilized, so that the heat transfer of the internal structure of the pouring sealant is uniform, the pouring sealant which is uniformly heated is not easy to generate bubbles, the generation of the bubbles is inhibited, and the properties of the epoxy resin pouring sealant after curing are ensured.

2. The nano silicon dioxide fiber and the nano carbon fiber are matched, the needle-shaped fiber structure of the nano silicon dioxide fiber and the nano carbon fiber is easy to puncture bubbles, so that small bubbles are gradually combined into large bubbles, the large bubbles are easy to move to the surface of the potting adhesive, and the bubbles generated in the curing process of the potting adhesive are convenient to remove.

3. The nano-silica fiber and the nano-silica are matched, the nano-silica fiber and the nano-silica are stably bonded inside the epoxy resin pouring sealant through a better connection effect of the silane coupling agent, and when the pouring sealant is heated to expand, the nano-silica fiber and the nano-silica have better strength, so that the phenomena of bubbles and cracks generated by the expansion of the pouring sealant can be reduced, and the pouring sealant has good mechanical properties after being cured.

Detailed Description

The present application will be described in further detail with reference to examples.

Preparation example of nanocomposite fiber

Polyethylene glycol of the following raw materials was purchased from polyethylene glycol 800 manufactured by Jinan Yun Baihui Biotech limited; the nano carbon fiber is purchased from Zhejiang Yamei nano technology GmbH; the nano-silica fiber is purchased from Sichuan Chinesian science and technology Co., Ltd; other raw materials and equipment are all sold in the market.

Preparation example 1: the nano composite fiber is prepared by the following method:

0.5kg of polyethylene glycol is weighed and sprayed on the surface of 1kg of carbon nanofibers, then 1kg of nano-silica fibers are immediately added into the carbon nanofibers sprayed with the polyethylene glycol within 60s, the stirring is carried out at the rotating speed of 350r/min in the process of adding the nano-silica fibers, and the nano-composite fibers are prepared after the drying at room temperature.

Preparation example 2: the nano composite fiber is prepared by the following method:

0.3kg of polyethylene glycol is weighed and sprayed on the surface of 1kg of carbon nanofiber, then 0.8kg of nano-silica fiber is immediately added into the carbon nanofiber sprayed with the polyethylene glycol within 30s, the carbon nanofiber is stirred at the rotating speed of 350r/min in the process of adding the nano-silica fiber, and the nano-composite fiber is prepared after drying at room temperature.

Preparation example 3: the nano composite fiber is prepared by the following method:

0.8kg of polyethylene glycol is weighed and sprayed on the surface of 1kg of carbon nanofiber, then 1.4kg of nano-silica fiber is immediately added into the carbon nanofiber sprayed with the polyethylene glycol within 90s, the mixture is stirred at the rotating speed of 350r/min in the process of adding the nano-silica fiber, and the nano-composite fiber is prepared after drying at room temperature.

Preparation example of modified nano-silica the nano-silica of the following raw materials was purchased from Shanghai Huizi sub-nano New Material Co., Ltd., model SP-15; hydroxyl silicone oil is purchased from Shenzhen Jipeng silicon fluorine material Co., Ltd; other raw materials and equipment are all sold in the market.

Preparation example 4: the modified nano silicon dioxide is prepared by the following method:

0.25kg of hydroxyl silicone oil is weighed and sprayed on the surface of 1kg of nano silicon dioxide, the mixture is stirred at the rotating speed of 500r/min in the spraying process, the mixture is continuously stirred at the rotating speed of 500r/min for 3min after the spraying is finished, and the mixture is dried at room temperature and then is put into a grinding machine to be ground until the particle size is 70nm, so that the modified nano silicon dioxide is prepared.

Preparation example 5: the modified nano silicon dioxide is prepared by the following method:

0.1kg of hydroxyl silicone oil is weighed and sprayed on the surface of 1kg of nano silicon dioxide, the mixture is stirred at the rotating speed of 500r/min in the spraying process, the mixture is continuously stirred at the rotating speed of 500r/min for 3min after the spraying is finished, and the mixture is dried at room temperature and then is put into a grinding machine to be ground until the particle size is 40nm, so that the modified nano silicon dioxide is prepared.

Preparation example 6: the modified nano silicon dioxide is prepared by the following method:

0.4kg of hydroxyl silicone oil is weighed and sprayed on the surface of 1kg of nano silicon dioxide, the mixture is stirred at the rotating speed of 500r/min in the spraying process, the mixture is continuously stirred at the rotating speed of 500r/min for 3min after the spraying is finished, and the mixture is dried at room temperature and then is put into a grinding machine to be ground until the particle size is 100nm, so that the modified nano silicon dioxide is prepared.

Preparation of modified nano boron nitride the following raw materials of nano boron nitride were purchased from Shanghai Chaowei nanotechnology Co., Ltd; hydroxyl silicone oil is purchased from Shenzhen Jipeng silicon fluorine material Co., Ltd; other raw materials and equipment are all sold in the market.

Preparation example 7: the modified nano boron nitride is prepared by the following method:

0.2kg of hydroxyl silicone oil is weighed and sprayed on the surface of 1kg of nano boron nitride, the mixture is stirred at the rotating speed of 500r/min in the spraying process, the mixture is continuously stirred at the rotating speed of 500r/min for 3min after the spraying is finished, and the mixture is dried at room temperature and then is put into a grinding machine to be ground until the particle size is 70nm, so that the modified nano boron nitride is prepared.

Preparation example 8: the modified nano boron nitride is prepared by the following method:

0.1kg of hydroxyl silicone oil is weighed and sprayed on the surface of 1kg of nano boron nitride, the mixture is stirred at the rotating speed of 500r/min in the spraying process, the mixture is continuously stirred at the rotating speed of 500r/min for 3min after the spraying is finished, and the mixture is dried at room temperature and then is put into a grinding machine to be ground until the particle size is 40nm, so that the modified nano boron nitride is prepared.

Preparation example 9: the modified nano boron nitride is prepared by the following method:

0.3kg of hydroxyl silicone oil is weighed and sprayed on the surface of 1kg of nano boron nitride, the mixture is stirred at the rotating speed of 500r/min in the spraying process, the mixture is continuously stirred at the rotating speed of 500r/min for 3min after the spraying is finished, and the mixture is dried at room temperature and then is put into a grinding machine to be ground until the particle size is 100nm, so that the modified nano boron nitride is prepared.

Examples

The epoxy resin in the following raw materials is purchased from corridor Environment-friendly science and technology Limited; the curing agent is purchased from T31 curing agent produced by Jinchuan chemical company Limited in Jinan province; the nano carbon fiber is purchased from Zhejiang Yamei nano technology GmbH; the nano-silica fiber is purchased from Sichuan Chinesian science and technology Co., Ltd; other raw materials and equipment are all sold in the market.

Example 1: an epoxy resin pouring sealant:

100kg of epoxy resin, 20kg of curing agent, 5kg of nano composite fiber, 8kg of nano particles and 8kg of compatilizer; the nano composite fiber consists of nano carbon fiber and nano silicon dioxide fiber in a weight ratio of 1: 1; the nano particles consist of modified nano silicon dioxide and modified nano boron nitride in a weight ratio of 1: 2; the modified nano-silica prepared in preparation example 4 is selected as the modified nano-silica, and the modified nano-boron nitride prepared in preparation example 7 is selected as the modified nano-boron nitride; the compatilizer is silane coupling agent KH-550; the preparation method comprises the following steps:

s1, weighing and mixing the nano carbon fibers and the nano silicon dioxide fibers, and stirring at the rotating speed of 80r/min for 5min to obtain nano composite fibers; mixing the modified nano silicon dioxide and the modified nano boron nitride, and stirring at the rotating speed of 200r/min for 2min to prepare nano particles; weighing epoxy resin, a curing agent, nano composite fibers and nano particles, mixing, stirring at the rotating speed of 500r/min for 10min, adding a silane coupling agent KH-550, and continuously stirring for 5min to obtain the finished pouring sealant.

Example 2: the present embodiment is different from embodiment 1 in that:

90kg of epoxy resin, 15kg of curing agent, 2kg of nano composite fiber, 5kg of nano particles and 5kg of compatilizer; the silane coupling agent is KH-560;

the preparation process comprises the following steps: weighing epoxy resin, a curing agent, nano composite fibers and nano particles, mixing, stirring at the rotating speed of 350r/min for 10min, adding a silane coupling agent, and continuously stirring for 5min to obtain the finished pouring sealant.

Example 3: the present embodiment is different from embodiment 1 in that:

110kg of epoxy resin, 25kg of curing agent, 8kg of nano composite fiber, 12kg of nano particles and 12kg of compatilizer;

the preparation process comprises the following steps: weighing epoxy resin, a curing agent, nano composite fibers and nano particles, mixing, stirring at the rotating speed of 1000r/min for 10min, adding a silane coupling agent, and continuously stirring for 5min to obtain the finished pouring sealant.

Example 4: the present embodiment is different from embodiment 1 in that:

the nanocomposite fibers prepared in preparation example 1 were selected as the nanocomposite fibers.

Example 5: the present embodiment is different from embodiment 1 in that:

the nanocomposite fibers prepared in preparation example 2 were selected as the nanocomposite fibers.

Example 6: the present embodiment is different from embodiment 1 in that:

the nanocomposite fibers prepared in preparation example 3 were selected as the nanocomposite fibers.

Example 7: this embodiment is different from embodiment 4 in that:

the modified nano-silica prepared in preparation example 5 is selected as the modified nano-silica in the raw materials; the modified nano boron nitride prepared in preparation example 8 is selected as the modified nano boron nitride in the raw materials.

Example 8: this embodiment is different from embodiment 4 in that:

the modified nano-silica in the raw materials is the modified nano-silica prepared in the preparation example 6; the modified nano boron nitride prepared in preparation example 9 is selected as the modified nano boron nitride in the raw materials.

Example 9: this embodiment is different from embodiment 4 in that:

the nano-composite fiber raw material is prepared by replacing nano-silica fibers with nano-carbon fibers with the same total mass.

Example 10: this embodiment is different from embodiment 4 in that:

in the preparation process of the nano composite fiber, the nano silicon dioxide fiber is added into the nano carbon fiber sprayed with the polyethylene glycol at one time.

Example 11: this embodiment is different from embodiment 4 in that:

the nano-particle raw material is modified nano-silicon dioxide with the same mass to replace modified nano-boron nitride.

Example 12: this embodiment is different from embodiment 4 in that:

the nano particles consist of nano silicon dioxide and nano boron nitride in a weight ratio of 1: 2; the nanometer silicon dioxide is selected from nanometer silicon dioxide produced by Shanghai Huizi Xiannao New Material Co., Ltd, with a model of 10nm, and the nanometer boron nitride is selected from Shanghai MaoGuo nanometer technology Co., Ltd, with a model of 100 nm.

Comparative example

Comparative example 1: this comparative example differs from example 1 in that:

the nano-composite fiber with the same mass replaces the nano-particles in the raw material.

Comparative example 2: this comparative example differs from example 1 in that:

the raw materials are not added with a compatilizer.

Comparative example 3: this comparative example differs from example 1 in that:

epoxy resin potting adhesive was purchased from Noke New materials science and technology Co., Ltd, Dongguan.

Performance test

1. Test for detecting number of bubbles and number of cracks

The preparation methods of the embodiments 1-12 and the comparative examples 1-3 are respectively adopted to prepare the pouring sealant, 200g of the finished pouring sealant is poured into a mold, the length, width and height of the mold are 15cm, 10cm and 4cm, the mold is placed under the conditions of 50 ℃ and 55% of relative humidity, after the pouring sealant is completely cured, the cured pouring sealant is taken out of the mold, then the mold is horizontally placed, the pouring sealant is cut along the horizontal direction, the height central line of the pouring sealant is used as a bisector and is evenly divided into two equal parts, when the pouring sealant is cured in the mold, the part of the pouring sealant close to the top of the mold is marked as part A, the part of the pouring sealant close to the bottom of the mold is marked as part B, the surface air hole number and the crack number of the parts A and B are visually observed, and a magnifier can be used as necessary.

2. Test for measuring curing time

The preparation methods of the examples 1-12 and the comparative examples 1-3 are respectively adopted to prepare the pouring sealant, 200g of the finished pouring sealant is poured into a mold, the length of the mold is 15cm, the width of the mold is 10cm, and the height of the mold is 4cm, the mold is placed under the conditions of 50 ℃ and 55% of relative humidity, the complete curing time of the mold is recorded, the properties of the tentative pouring sealant are continuously touched in the curing process, and the complete curing is completed when the pouring sealant is completely cured into a solid.

TABLE 1 Table for detecting number of pores, number of cracks and curing time

It can be seen from the combination of the embodiment 1 and the embodiments 2 to 3 and the combination of table 1 that, in the embodiment 1, the nano composite fibers and the nano particles in a proper proportion are adopted to be matched, so that bubbles can be promoted to move in the potting adhesive, uniform heating is realized in the curing process of the potting adhesive under the condition of short curing time, the bubbles can move towards the curing surface, and the bubbles appearing in the potting adhesive in the curing process are broken.

It can be seen from the combination of example 1 and examples 4-6 and table 1 that, in examples 4-6, the nanocomposite fibers prepared in preparation examples 1-3 are respectively used, and compared with example 1, the number of pores and cracks of the potting adhesive prepared in examples 4-6 are smaller than those of example 1; the carbon nanofibers and the nano-silica fibers are stably dispersed in the epoxy resin under the matching action of the polyethylene glycol to form a staggered network structure, and the uniform heat conduction of the pouring sealant is realized in the curing process under the premise of shorter curing time by matching the transmission effect of the nanoparticles, so that bubbles and cracks generated due to nonuniform heating in the curing process of the pouring sealant are reduced.

The curing time of examples 4-6 is slightly longer than that of example 1, which shows that the thermal conductivity of the carbon nanofibers whose surfaces are sprayed with polyethylene glycol is easily affected, thereby affecting the curing time of the potting adhesive prepared in examples 4-6.

By combining example 4 and examples 7-8 with table 1, it can be seen that the raw materials of examples 7-8 have different ratios of the modified nano-silica to the modified nano-boron nitride, and the different ratios of the raw materials have different heat conduction effects, so that the heating uniformity during the curing process of the potting adhesive is easily affected, and the curing time is affected.

By combining example 4 and examples 9-12 and table 1, it can be seen that in example 9, the nano-composite fiber raw material is replaced by nano-carbon fibers with the same mass, compared with example 4, the number of pores and cracks of the potting adhesive prepared in example 9 is higher than those of example 4; the nano-silicon dioxide fiber can be better compatible with epoxy resin under the coordination of the compatilizer, and the nano-carbon fiber is well dispersed in the pouring sealant by virtue of the connection effect of the polyethylene glycol on the nano-carbon fiber and the nano-silicon dioxide fiber, so that the probability of generating bubbles and cracks due to the compatibility problem is reduced in the heating and curing process.

Example 10 in the preparation process of the nano composite fiber, the nano silica fiber is added to the carbon nanofiber sprayed with the polyethylene glycol at one time, compared with example 4, the number of pores and cracks of the pouring sealant prepared in example 10 is higher than those of example 4, and the curing time is longer than that of example 4; the one-time addition is easy to cause the mixing of the nano silicon dioxide fiber and the nano carbon fiber to be uneven, thereby easily influencing the bubble discharge condition; the quantity of the bubbles of the part A is larger than that of the bubbles of the part B, because the internal bubbles still gradually move towards the surface in the curing process of the pouring sealant, the moving speed of the bubbles of the part is lower, and the bubbles are not moved to the surface to be broken easily when the curing of the pouring sealant is finished, so that the quantity of the bubbles in the curing process of the pouring sealant is easily influenced.

In example 11, modified nano-silica with the same mass is used to replace modified nano-boron nitride in the nanoparticle raw material, compared with example 4, the number of pores and cracks of the potting adhesive prepared in example 11 is higher than those of example 4, and the curing time is longer than that of example 4; the modified nano-silica and the modified nano-boron nitride are matched, attached to the surface of the nano-composite fiber and contacted with a network structure formed by the nano-composite fiber, and the modified nano-silica is well bonded with the epoxy resin under the matching action of the compatilizer, so that bubbles in the curing process are promoted to move towards the surface in the pouring sealant.

In example 12, commercially available nano-silica and commercially available nano-boron nitride are selected, that is, the nano-silica and the nano-boron nitride are not modified, and compared with example 4, the number of pores and cracks of the pouring sealant prepared in example 12 are higher than those of example 4; the modified nano silicon dioxide is matched with the modified nano boron nitride, and through the better hydrophobic effect of the hydroxyl silicone oil on the surface of the modified nano silicon dioxide, water vapor in the external environment is prevented in the curing process of the pouring sealant, so that bubbles are generated in the curing process of the pouring sealant; by means of the good filling effect of the nano boron nitride, the heat conduction uniformity of the pouring sealant is good, and therefore the probability of bubbles generated in the curing process of the pouring sealant is reduced; meanwhile, as the nano boron nitride is not added, the curing time of the pouring sealant is influenced.

By combining example 1 and comparative examples 1-3 and table 1, it can be seen that, in the raw material of comparative example 1, the nano-composite fibers with the same mass are used for replacing the nano-particles, compared with example 1, the number of pores and the number of cracks of the pouring sealant prepared in comparative example 1 are both greater than those of example 1, and the curing time is longer than that of example 1; the nano composite fiber and the nano particles are matched, and the pouring sealant can be uniformly heated in the heating and curing process, so that the generation of bubbles is reduced.

Compared with the example 1, the pouring sealant prepared in the comparative example 2 has more pores and cracks than those of the example 1, and the curing time is longer than that of the example 1; the nano composite fiber and the nano particles can improve the compatibility effect with the epoxy resin under the action of the compatilizer, so that the epoxy resin is tightly connected with the nano composite fiber and the nano particles, and the generation of bubbles and cracks is reduced.

Comparative example 3 the epoxy resin potting adhesive is a commercially available epoxy resin potting adhesive, compared with example 1, the number of pores and the number of cracks of the potting adhesive prepared in comparative example 3 are both larger than those of example 1, and the curing time is longer than that of example 1; the curing time of the commercially available epoxy resin pouring sealant is obviously longer than that of the epoxy resin pouring sealant in example 1, and the number of bubbles and the number of cracks in the comparative example 3 are larger than those in example 1, which shows that in the heating and curing process of the commercially available epoxy resin, the local reaction of the epoxy resin pouring sealant is easy to be fast due to the difficulty in controlling the temperature rise time and the uniform heating degree, so that the bubbles are easy to generate, and the property of the epoxy resin pouring sealant is influenced.

3. Heat conductivity coefficient test

The preparation methods of the examples 1-12 and the comparative examples 1-2 are respectively adopted to prepare the pouring sealant, 200g of the finished pouring sealant is poured into a mold, the length of the mold is 15cm, the width of the mold is 10cm, and the height of the mold is 4cm, the pouring sealant is cured for 24 hours under the condition of 25 ℃, a sample to be tested with specified dimensions is cut by adopting ASTM D5470 and is tested, and the thermal conductivity coefficients of the pouring sealants of the examples 1-12 and the comparative examples 1-3 are respectively detected.

4. Tensile shear strength test

The preparation methods of examples 1-12 and comparative examples 1-2 are respectively adopted to prepare the pouring sealant, the pouring sealant is cured for 24 hours at 25 ℃, and the tensile shear strength of the pouring sealants prepared in examples 1-12 and comparative examples 1-3 is respectively detected by measuring the tensile shear strength of the GB/T7124-2008 adhesive.

5. Dispersion stability test

The preparation methods of the examples 1-12 and the comparative examples 1-2 are respectively adopted to prepare the pouring sealant, the pouring sealant is poured into a barrel with the diameter of 30cm and the depth of 50cm for sealed storage for 6h, the pouring sealant glue solution at the positions 10cm, 20cm, 30cm, 40cm and 50cm away from the surface of the pouring sealant is taken out by a spoon, whether the nano composite fiber and the nano particle are contained is observed, and if the pouring sealant glue solution taken out at each position contains the nano composite fiber and the nano particle, the nano composite fiber and the nano particle have good dispersion stability in the pouring sealant.

TABLE 2 Heat conduction, tensile shear strength, and dispersion stability testing table

Item	Thermal conductivity (W/(m.K))	Tensile shear Strength (MPa)	Is uniformly dispersed
				Example 1	0.45	16.4	Is that
Example 2	0.40	15.5	Is that
				Example 3	0.48	16.8	Is that
Example 4	0.42	20.5	Is that
				Example 5	0.44	20.1	Is that
Example 6	0.41	21.0	Is that
				Example 7	0.40	19.7	Is that
Example 8	0.41	19.3	Is that
				Example 9	0.50	17.4	Whether or not
Example 10	0.34	18.5	Whether or not
				Example 11	0.22	20.7	Is that
Example 12	0.45	19.1	Is that
				Comparative example 1	0.48	16.0	Is that
Comparative example 2	0.44	6.8	Whether or not
				Comparative example 3	0.25	16.0	/

It can be seen from the combination of example 1 and examples 2-3 and table 2 that the prepared potting adhesive has good thermal conductivity, good tensile shear strength and uniform dispersion, which indicates that the carbon nanofibers, the nano-silica fibers and the nanoparticles are matched to ensure good thermal conductivity of the potting adhesive, and the potting adhesive has good mechanical property indexes through the filling effect.

Combining examples 1 and 4-6 with Table 2, it can be seen that, using the nanocomposite fibers prepared in preparation examples 1-3 in examples 4-6, respectively, compared to example 1, examples 4-6 have a slightly lower thermal conductivity than example 1, but a higher tensile shear strength than example 1; the thermal conductivity effect of the carbon nanofibers is easily affected under the action of the polyethylene glycol, but the mechanical strength of the pouring sealant can be improved by adding the polyethylene glycol.

Combining example 4 with examples 9-12 and combining table 2, it can be seen that, in example 9, the nano-composite fiber raw material is replaced by nano-carbon fiber with the same mass as nano-silica fiber, compared with example 4, the thermal conductivity of example 9 is slightly larger than that of example 4, and the dispersion effect is not good; the nano carbon fiber has a good heat conduction effect and can improve the heat conduction performance of the pouring sealant, but the tensile shear strength of the embodiment 9 is lower than that of the embodiment 4, so that the compatibility of the nano carbon fiber and the epoxy resin is poor, and the mechanical property and the dispersion uniformity of the pouring sealant are easy to realize.

Example 10 in the preparation process of the nano composite fiber, the nano silica fiber is added to the carbon nanofiber sprayed with the polyethylene glycol at one time, compared with example 4, the thermal conductivity of example 10 is lower than that of example 4, the tensile shear strength of example 10 is lower than that of example 4, and the dispersion stability is poor; the operation means of one-time addition is inconvenient for uniform mixing, thereby influencing the heat conductivity coefficient, the mechanical property and the dispersion stability.

Example 11 in the nanoparticle raw material, modified nano-silica with the same mass is used to replace modified nano-boron nitride, compared with example 4, the thermal conductivity of example 11 is smaller than that of example 4, and the tensile shear strength of example 11 is slightly larger than that of example 4; the modified nano silicon dioxide and the modified nano boron nitride are matched, so that the pouring sealant has good thermal conductivity and good mechanical properties.

In example 12, commercially available nano-silica and commercially available nano-boron nitride are selected, that is, the nano-silica and the nano-boron nitride are not modified, and compared with example 4, the tensile shear strength of example 12 is lower than that of example 4, which shows that the hydroxyl group in the hydroxyl silicone oil can promote the curing of the epoxy resin and improve the strength after the curing.

It can be seen by combining example 1 and comparative examples 1-3 and table 2 that the nanoparticles are replaced by the nano-composite fibers with the same mass in the raw material of comparative example 1, compared with example 1, the tensile shear strength of comparative example 1 is lower than that of example 1, which shows that the nano-composite fibers and the nanoparticles are matched, a fiber skeleton is formed by a network structure formed by the nano-composite fibers, and the filling effect of the nanoparticles is matched to ensure that the pouring sealant has uniform heat conduction and good heat conduction performance.

Comparative example 2 the raw material is not added with the compatilizer, and compared with example 1, comparative example 2 has poor dispersion stability and poor tensile shear strength, which shows that the compatibility of the nano composite fiber and the nano particles in the epoxy resin is poor easily, and the tensile shear strength and the dispersion stability are influenced.

Comparative example 3 the epoxy resin potting adhesive is a commercially available epoxy resin potting adhesive, and compared with example 1, the thermal conductivity coefficient is lower than that of example 1, which shows that the nano composite fiber and the nano particles are matched to make the finished product potting adhesive have good thermal conductivity.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims (3)

1. The epoxy resin pouring sealant is characterized by being prepared from the following raw materials in parts by weight: 90-110 parts of epoxy resin, 15-25 parts of curing agent, 2-8 parts of nano composite fiber, 5-12 parts of nano particles and 5-12 parts of compatilizer; the nano composite fiber consists of nano carbon fiber and nano silicon dioxide fiber in the weight ratio of 1: 0.8-1.4; the compatilizer is a silane coupling agent;

the nano composite fiber is prepared by the following method:

weighing carbon nanofibers, nano-silica fibers and polyethylene glycol according to a weight ratio of 1:0.8-1.4:0.3-0.8, spraying polyethylene glycol on the surfaces of the carbon nanofibers, immediately adding the nano-silica fibers into the carbon nanofibers sprayed with polyethylene glycol within 30-90s, stirring in the adding process, and drying to obtain nano-composite fibers; the nano particles consist of modified nano silicon dioxide and modified nano boron nitride in a weight ratio of 1: 1-3;

the modified nano silicon dioxide is prepared by the following method:

spraying hydroxyl silicone oil on the surface of the nano silicon dioxide, wherein the weight ratio of the nano silicon dioxide to the hydroxyl silicone oil is 1:0.1-0.4, drying, and grinding until the particle size is 40-100nm to obtain modified nano silicon dioxide;

the modified nano boron nitride is prepared by the following method:

and (2) spraying hydroxyl silicone oil on the surface of the nano boron nitride, wherein the weight ratio of the nano boron nitride to the hydroxyl silicone oil is 1:0.1-0.3, drying, and grinding until the particle size is 40-100nm to obtain the modified nano boron nitride.

2. The preparation method of the epoxy resin pouring sealant as claimed in claim 1, characterized by comprising the following steps:

weighing epoxy resin, curing agent, nano composite fiber and nano particles, mixing and stirring, adding compatilizer, continuously mixing and stirring to obtain the finished pouring sealant.

3. The method for preparing epoxy resin pouring sealant as claimed in claim 2, wherein the stirring speed is 350-1000 r/min.