WO2020258620A1 - Modified epoxy organic silicon high-thermal-conductivity insulating impregnating varnish and preparation method thereof - Google Patents

Abstract

Disclosed are an insulating impregnating varnish and a preparation method thereof. The insulating impregnating varnish comprises a matrix resin, a diluent and a curing agent, wherein the matrix resin is prepased by condensation of a modified epoxy resin with an organic silanol having a Si-OH group, the raw materials of the modified epoxy resin comprise an epoxy resin, a vinyl monomer containing an ester groupand a hydrophobic hexagonal boron nitride nanosheet containing a vinyl group, and the modified epoxy resin is prepared by polymerization of the epoxy resin with the remaining raw materials, and the boron nitride nanosheet is prepared by a specific method comprising: treaing by surface hydroxyl modification and freeze-thaw expansion, performing in one-pot method boron nitride stripping and catalytic esterification modification by binding with a specific compound. The insulating impregnating varnish is prepared by mixing and stirring the matrix resin, the diluent and the curing agent. The insulating impregnating varnish has the advantages of not only high thermal conductivity coefficient, low dielectric loss, high and low temperature impact resistance, good bonding strength, good permeability, high electric field strength and high mechanical strength, but also stable product quality between batches during preparation.

Description

Modified epoxy organic silicon high thermal conductivity insulating impregnating varnish and preparation method thereof

This application claims the priority of the invention patent application with application number 201910558993.7 filed with the State Intellectual Property Office of China on June 26, 2019. The content of the priority text is expressly incorporated into this application by reference.

Technical field

This application belongs to the technical field of polymer composite materials and electrical engineering, and specifically relates to a modified epoxy silicone high thermal conductivity insulating dipping varnish and a preparation method thereof.

Background technique

Insulation impregnating varnish is mainly used for the insulation dipping treatment of motors, transformers and winding coils of random reactance to fill the gaps between the coils and the gaps between the coils and surrounding objects (such as iron cores, interlayer insulation strips, heat shrinkable sleeves, etc.). Bonding the coil wire and the wire, the wire and other objects, mainly for electrical insulation and bonding molding, improving the mechanical properties, electrical strength and protective performance of the coil. Insulating impregnating varnish can also be used for the impregnation of electronic components, Painting or packaging materials.

With the development of large-capacity, miniaturization and high-efficiency equipment such as motors and electrical appliances, the heat dissipation capacity of various parts of the motor, especially the insulating parts, directly affects the temperature rise of the motor. If the temperature rise of the motor exceeds the limit, it will cause insulation aging, The coil breaks down and the motor burns down. If the insulating impregnating varnish has both high thermal conductivity and electrical insulation performance, it can effectively reduce the temperature rise of the motor winding, thereby reducing the size of the motor and increasing the output of the motor. In addition, with the rapid development of today’s microelectronic integration technology and high-density assembly technology, the ability of electronic components to dissipate heat in time has become a key limiting factor affecting their normal operation and service life. It has excellent comprehensive performance such as high reliability and good heat dissipation. Thermally conductive insulating impregnating varnish (resin), as a coating or packaging material for the thermal interface, quickly dissipates the heat generated during the operation of the components to ensure the normal operation of electronic equipment. The development of a new type of high thermal conductivity insulating material to solve the problem of structural heat dissipation, and to improve the thermal conductivity of the insulating layer in the motor is one of the important measures to improve the insulation of the motor and reduce the loss. There are still more or less problems with lacquer.

For example, Chinese patent application CN101381583B discloses a high thermal conductivity silicone impregnating varnish, which is made from three types of aluminum nitride powders with different average particle sizes, but also with high thermal conductivity and high insulation properties. Filler, and add the mixed mixed aluminum nitride powder filler to the silicone prepolymer, then add the catalyst and curing agent, and mix it uniformly through conventional ball milling. The thermal conductive filler has a particle size of 5-20μm, and the amount is 20 % Or more; Another example is the Chinese patent application CN101864145A which discloses a high thermal conductivity insulating impregnating resin for hollow reactors and a preparation method thereof. The impregnating resin is composed of epoxy resin, toughening agent, curing agent, curing accelerator, silicon powder, trioxide Dialuminum powder and sericite powder and other inorganic powders are stirred, heated to 60～75℃ and degassed under reduced pressure. The amount of thermally conductive filler is as high as 45%. The thermal conductivity of the insulating paint obtained above can reach 0.386 respectively. ～0.502W/(m·k), 0.35～0.90W/(m·K), but both affect the mechanical properties, and at the same time have a greater impact on the viscosity, reduce the permeability of the impregnating paint, and have poor fluidity, which is not conducive to the formation The integral insulating structure without air gap is not conducive to impregnation treatment; another example is the Chinese patent application CN102295878A published a kind of filled thermally conductive insulating impregnating varnish, which uses inorganic powder with high thermal conductivity and high insulation performance as the filler ( It is specifically modified by silane), which is added to the modified epoxy resin, then dispersant, peroxide initiator and reactive diluent are added, and the mixture is obtained. Although the thermal conductivity of the thermally conductive impregnating paint is greatly improved, it can reach 0.31 -0.5W/(m·K), but there is a great probability of uneven dispersion in practical applications, and sedimentation, agglomeration of nanoparticles, and unstable product quality between batches, which affects the thermal conductivity and electromechanical properties of the product.

At the same time, high thermal conductivity insulating varnish or resin needs to be applied to the insulation system of large and medium-sized high-voltage generators or electronic components. Not only must the thermal conductivity be improved, but also low dielectric loss, high electric field strength, excellent toughness, high and low temperature impact resistance, Good bonding strength, etc. In addition, it also requires good penetration performance. It is difficult for current impregnating paints to meet the above requirements at the same time.

Application content

The purpose of this application is to overcome the shortcomings of the prior art and provide an improved insulating impregnating varnish, which has high thermal conductivity, low dielectric loss, high and low temperature impact resistance, good bonding strength, good permeability, and high electric field strength. And on the basis of higher mechanical strength, it has the advantages of stable product quality between batches during preparation.

The application also provides a method for preparing the above-mentioned insulating dipping varnish.

In order to solve the above technical problems, this application adopts the following technical solution: an insulating impregnating varnish, including a matrix resin, a diluent and a curing agent, the matrix resin is a condensation of modified epoxy resin with silicone alcohol The raw materials of the modified epoxy resin include epoxy resin, vinyl monomers containing ester groups, and hydrophobic hexagonal boron nitride nanosheets containing vinyl groups. The epoxy resin and the remaining raw materials are polymerized and made; wherein the hydrophobic hexagonal boron nitride nanosheets containing vinyl are prepared by the following method:

(1) Surface hydroxylation modification of hexagonal boron nitride to prepare hydroxylated hexagonal boron nitride;

(2) subjecting the hydroxylated hexagonal boron nitride prepared in step (1) to freeze-thaw expansion treatment to prepare expanded hydroxylated hexagonal boron nitride;

(3) The expanded hydroxylated hexagonal boron nitride prepared in step (2) and the compound represented by formula (I) are mixed and stirred in the first solvent to obtain a first mixed solution, and then added to the obtained first mixed solution Adding unsaturated acid and/or unsaturated acid anhydride and a second solvent to react to prepare the hydrophobic hexagonal boron nitride nanosheets containing vinyl groups;

Wherein, R ₀ is a C _1-6 alkyl group.

According to some preferred aspects of the present application, the vinyl monomer containing an ester group is a combination of one or more selected from the compounds represented by formula (II):

In the formula, R ₁ is a C _1-10 alkyl group, R ₂ and R ₃ are each independently hydrogen or a C _1-10 alkyl group; C _1-10 alkyl group includes methyl, ethyl, propyl, Isopropyl, butyl, pentyl, isopentyl, neopentyl, hexyl, etc.

According to some specific aspects of the present application, in formula (II), at least one of R ₂ and R ₃ is hydrogen.

More preferably, the vinyl monomer containing an ester group is at least two selected from the compounds represented by formula (II). According to a specific aspect of the present application, the vinyl monomer containing an ester group is a combination of methyl methacrylate (MAA) and butyl acrylate (BA).

According to some preferred aspects of the present application, the epoxy resin is a bisphenol epoxy resin.

According to some preferred and specific aspects of the present application, the bisphenol epoxy resin is a combination of one or more selected from the compounds represented by formula (III):

(Ⅲ), where: R ₄ is -C(CH ₃ ) ₂ -, -CH ₂ -or -S(O) ₂ -, n is an integer selected from 0-10, that is, n can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. According to a specific aspect of the present application, the epoxy resin is epoxy resin E-51 and/or epoxy resin E-44.

According to some preferred aspects of the present application, in the process of preparing the vinyl-containing hydrophobic hexagonal boron nitride nanosheets, the epoxy resin, the vinyl-containing hydrophobic hexagonal boron nitride nanosheets and the The feed mass ratio of the vinyl monomer containing the ester group is 1:0.05-0.1:0.15-0.4. More preferably, the feed mass ratio of the epoxy resin, the hydrophobic hexagonal boron nitride nanosheets containing vinyl groups and the vinyl monomers containing ester groups is 1:0.05-0.085:0.18-0.32.

According to some preferred aspects of the present application, the polymerization reaction is carried out at a temperature of 100-120°C. More preferably, the polymerization reaction is carried out at a temperature of 105-115°C.

According to some specific aspects of the present application, in step (1), the hydroxylated hexagonal boron nitride is prepared by the following method: mixing hexagonal boron nitride and sodium hydroxide aqueous solution, stirring and reacting at a temperature of 90-150°C to prepare to make.

In some embodiments of the present application, in step (1), the hexagonal boron nitride is a commercially available product with a purity greater than or equal to 99% and a particle size of about 2-5 μm.

According to some specific and preferred aspects of the present application, in step (1), the temperature is achieved by an oil bath heating method.

According to some specific aspects of the present application, in step (1), after the stirring reaction, it further includes a step of washing with distilled water until the washing becomes neutral, and drying to obtain the hydroxylated hexagonal boron nitride.

According to some preferred aspects of the present application, in step (2), the operation of the freeze-thaw swelling treatment is: preparing the hydroxylated hexagonal boron nitride prepared in step (1) into an aqueous solution, and placing the resulting aqueous solution in the first setting Frozen at a temperature, and then thawed to a second set temperature, and repeated freezing and thawing steps in this way to prepare the expanded hydroxylated hexagonal boron nitride; wherein, the first set temperature is -50～-5 ℃, the second set temperature is 10-30℃. More preferably, the first set temperature is -45 to -15°C, and the second set temperature is 18 to 28°C.

According to some specific aspects of the present application, in step (2), the mass fraction of the aqueous solution is 5-20%.

According to some specific aspects of the present application, in step (2), the freezing processing time is 1-8h.

According to some specific aspects of the present application, in step (2), the number of cycles is 4-12 times.

According to some specific and preferred aspects of the present application, in step (3), R ₀ in formula (I) can be methyl, ethyl, propyl, butyl or pentyl.

According to some preferred aspects of the present application, in step (3), the mixing and stirring are performed at a temperature of 60-78°C. More preferably, in step (3), the mixing and stirring are performed at a temperature of 65 to 75°C. In some specific embodiments of the present application, the mixing and stirring may be performed by ultrasonic waves, and the mixing and stirring may be heated in a water bath to achieve temperature control.

According to some preferred aspects of the present application, in step (3), the reaction in the second solvent is carried out at a temperature of 80 to 120° C. in the presence of an inert gas. More preferably, in step (3), the reaction in the second solvent is carried out at a temperature of 85-115°C. Wherein, the inert gas includes nitrogen, argon and the like.

According to some preferred aspects of the present application, in step (3), the mixing and stirring are controlled to be performed in an anhydrous environment. In some specific embodiments of the present application, the raw material and the moisture in the environment can be separated by refluxing water to realize mixing and stirring in an anhydrous environment.

According to some preferred aspects of the present application, in step (3), the mass ratio of the compound represented by the formula (I) to the expanded hydroxylated hexagonal boron nitride is 6-12:1.

According to some preferred aspects of the present application, the feed mass ratio of the unsaturated acid and/or unsaturated acid anhydride to the expanded hydroxylated hexagonal boron nitride is 0.05-0.5:1.

According to some preferred aspects of the present application, the first solvent is cyclohexane, and the second solvent is ethyl acetate.

According to some preferred aspects of the present application, the unsaturated acid is linoleic acid and/or methacrylic acid, and the unsaturated acid anhydride is itaconic anhydride and/or maleic anhydride.

The above-mentioned method for preparing hydrophobic hexagonal boron nitride nanosheets containing vinyl groups provided in this application is different from the prior art, and it can not only realize the one-pot method of stripping and hydrophobic modification of boron nitride nanosheets without separation Intermediate, at the same time, the compound of formula (I) can be reused, and the high yield of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups can be achieved, and the modification is thorough. There is almost no unmodified boron nitride nanosheets. Exist, and then can achieve industrialized mass production.

According to some preferred aspects of the present application, in preparing the matrix resin, the mass ratio of the modified epoxy resin to the organosilicon alcohol with silanol is 1:0.15-0.35. More preferably, in preparing the matrix resin, the mass ratio of the modified epoxy resin to the organosilicon alcohol with silanol is 1:0.20-0.35.

According to some preferred aspects of the present application, the condensation reaction is performed on a catalyst at 120-180° C., and the ratio of the feed mass of the catalyst to the modified epoxy resin is 0.005-0.015:1.

According to some preferred aspects of the present application, the catalyst is cobalt naphthenate.

In some preferred embodiments of the present application, the preparation method of the matrix resin is as follows: first add the modified epoxy resin and the xylene solution of the organosilicon alcohol into the reactor, and slowly increase the temperature to 140-160 ℃, reflux reaction for 45min, gradually remove the solvent until the solid content reaches 80-88%, add catalyst, continue the water separation and reflux reaction, until the 60-70%wt viscosity reaches 80-100sec (tu 4# cup, 25℃), and finally cool down At 110-130°C, the solvent in the reaction system is removed by distillation under reduced pressure, and the matrix resin is obtained by filtration.

According to some specific aspects of the present application, the mass fraction of the organosilicon alcohol in the xylene solution of the organosilicon alcohol is 40-60%. According to a specific aspect of the present application, the mass fraction of the organosilicon alcohol in the xylene solution of the organosilicon alcohol is 50%.

According to some preferred aspects of this application, the organosilicon alcohol with silanol is a compound represented by the following formula:

In the formula, e, f, g, h, i, and q are independently numbers between 0 and 20, and e, h, and i are not 0 at the same time, and e, f, and g are not 0 at the same time. , G is 0, q is not 0; R ¹ , R ² , and R ^{3 are} independently methyl, vinyl or phenyl.

According to some preferred aspects of the present application, in the structural formula of the above-mentioned organosilanol with silanol, the total number of moles of phenyl, methyl and vinyl attached to the Si atom is 1.30-1.70, and the phenyl group accounts for the total number of moles on the Si atom. The ratio of the total moles of the connected phenyl, methyl and vinyl groups is 18%-50%; the mass content of the vinyl groups in the organosilicon alcohol is 0.5%-10%.

According to some preferred aspects of the present application, the above-mentioned organosilicon alcohol with silanol has a temperature index of 180°C to 220°C measured according to the secant method, and a molecular weight measured according to the GPC method of 500-8000.

According to some preferred and specific aspects of the application, the organosilicon alcohol with silanol is selected from TH-1# (R/Si=1.50, Ph/R=0.43, Vi quality) from Suzhou Taihu Electric New Materials Co., Ltd. Parts% = 4.1), TH-2# (R/Si = 1.58, Ph/R = 0.35, Vi mass parts% = 0.6) from Suzhou Taihu Electrical New Materials Co., Ltd., and TH from Suzhou Taihu Electrical New Materials Co., Ltd. -3#(R/Si=1.50, Ph/R=0.35, Vi mass parts %=3.2) one or more combinations of organosilicon alcohols can be prepared according to the method described in ZL201310090271.6. Got. In the above, R/Si represents the total number of methyl, phenyl, and vinyl groups attached to the Si atom in the silicon (number of moles); Ph/R represents the number of groups attached to the Si atom The proportion (molar ratio) of phenyl groups in all (methyl, phenyl, vinyl) groups; Vi mass fraction% represents the proportion (mass percentage) of vinyl in the silicon.

According to some specific aspects of the application, the diluent is polypropylene glycol diglycidyl ether or neopentyl glycol diglycidyl ether or a combination of both.

According to some specific aspects of the present application, the curing agent is methyltetrahydrophthalic anhydride or methylhexahydrophthalic anhydride or a combination of both.

According to some preferred aspects of the present application, in the insulating dipping varnish, the mass ratio of the base resin, the diluent and the curing agent is 1:0.05-0.25:0.35-0.7. More preferably, in the insulating dipping varnish, the mass ratio of the base resin, the diluent and the curing agent is 1:0.05-0.20:0.35-0.60.

Another technical solution provided by this application: a preparation method of the above-mentioned insulating dipping varnish, the preparation method comprising the following steps:

(a) Preparation of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups;

(b) The epoxy resin, the vinyl-containing hydrophobic hexagonal boron nitride nanosheets prepared in step (a), and the remaining raw materials are polymerized in the presence of an initiator in a third solvent to form the modified ring Oxygen resin

(c) Condensing the modified epoxy resin prepared in step (b) with the organosilicon alcohol having silanol groups to form the matrix resin;

(d) Mixing the matrix resin produced in step (c) with a diluent and a curing agent to prepare the insulating impregnating varnish.

According to some specific aspects of the present application, in step (b), the initiator is dibenzoyl peroxide (BPO).

According to some specific aspects of the present application, in step (b), the third solvent is n-butanol.

According to some specific aspects of this application, the specific implementation for preparing the modified epoxy resin is: (i) mix the epoxy resin with the third solvent and 1/4 of the initiator uniformly, and place them in the condensed water pipe, Into a nitrogen four-neck flask, add the hydrophobic hexagonal boron nitride nanosheets containing vinyl prepared in step (a), and heat the oil bath to 85-95°C for 10-60 minutes;

(ii) The temperature is raised to about 100-120℃, and at the same time, a constant pressure dropping funnel is used to dropwise add a vinyl monomer solution containing 3/4 of the initiator dissolved in the ester group, and slowly drop it. After the drop is completed, the temperature is kept for reaction 3 -4h, then under reduced pressure distillation to remove the third solvent (recyclable), ready.

According to some specific aspects of the present application, in step (d), the mixing is performed at a temperature of 20-50°C; and/or the mixing time is 30-60 min.

Due to the implementation of the above technical solutions, this application has the following advantages compared with the prior art:

This application innovatively uses vinyl monomers containing ester groups and hydrophobic hexagonal boron nitride nanosheets containing vinyl groups to polymerize and modify epoxy resins, so that the boron nitride nanosheets and epoxy resins are covalently modified. The addition amount of the hydrophobic hexagonal boron nitride nanosheets containing vinyl groups is very small, and the modified epoxy resin and the organosilicon alcohol with silanol are condensed to form a specific matrix resin, which effectively solves the problem. In order to achieve high thermal conductivity, the conventional impregnating paint adopts physical filling and the problems of difficulty in dispersion and uniformity and sedimentation, so that the impregnating paint of this application has high thermal conductivity, low dielectric loss, high and low temperature impact resistance, good bonding strength, and penetration. On the basis of good performance, high electric field strength and high mechanical strength, it has the advantages of stable product quality between batches during preparation;

At the same time, because the crude product of modified boron nitride nanosheets obtained by modifying boron nitride nanosheets in the prior art contains unmodified boron nitride nanosheets and it is difficult to achieve effective separation, the existing technology is adopted The modified boron nitride nanosheets directly obtained in the modified epoxy resin are unsatisfactory in all aspects. However, this application uses a specific method to prepare the hydrophobic hexagonal boron nitride nanosheets containing vinyl groups, specifically using surface hydroxyl groups. Modification, freeze-thaw expansion treatment, combined with the catalysis of boron nitride stripping and esterification modification with specific formula (I) compound, on the one hand, it realizes one-pot method for stripping and hydrophobic modification without separating intermediates At the same time, the compound of formula (I) can be reused, and the yield is high, which greatly saves the cost. On the other hand, the obtained crude product of the hydrophobic hexagonal boron nitride nanosheets containing vinyl has high purity, almost unchanged The flexible boron nitride or boron nitride nanosheets can be directly used in the preparation process of the modified epoxy resin of the present application, and will not affect the modified epoxy resin and the organosilicon alcohol with silanol after the condensation reaction. All aspects of the performance of the matrix resin, but has a gain effect.

Description of the drawings

Figure 1 is a transmission electron microscope (TEM) image of a hydrophobic hexagonal boron nitride nanosheet containing vinyl prepared in Example 3. The left and right sides are images of different magnifications;

2 is an atomic force microscope (AFM) image of the hydrophobic hexagonal boron nitride nanosheets containing vinyl groups prepared in Example 3;

3 is an XRD spectrum of the hydrophobic hexagonal boron nitride nanosheets containing vinyl groups prepared in Example 3. FIG.

Detailed ways

The application will be further described in detail below in conjunction with specific embodiments. It should be understood that these embodiments are used to illustrate the basic principles, main features, and advantages of the present application, and the present application is not limited by the following embodiments. The implementation conditions used in the examples can be further adjusted according to specific requirements, and the implementation conditions not specified are usually conditions in routine experiments. The raw materials used in the examples are all commercially available industrial products. In the following examples, unless otherwise specified, all raw materials are basically commercially available or prepared by conventional methods in the field.

Example 1

Preparation of the compound represented by formula (Ia) (that is, R ₀ in formula (I) is propyl): Weigh 15.8g (0.073mol) N-butylpyridine bromide ([bpy]Br) and 8g (0.073mol) (Sodium tetrafluoroborate) NaBF ₄ in a plastic washing bottle, add 100mL acetone as solvent, magnetically stir, condense and reflux at room temperature, react for 12h, stand still, filter under reduced pressure, discard the white solid NaBr, and get light yellow and clear On the filter night, add 100 mL of dichloromethane to the light yellow clear filter night, a white precipitate precipitates out, vacuum filtration, the filter night is concentrated by rotary evaporation to remove the acetone and dichloromethane, the resulting yellow oily liquid is vacuum at 60°C After drying for 8 hours, 13.8 g of the compound [bpy]BF ₄ represented by formula (Ia) was obtained, with a yield of 85.2%;

Example 2

The preparation of the compound represented by formula (Ib) (that is, R ₀ in formula (I) is methyl): add 28.2g (0.15mol) of bromo N-ethylpyridine into an Erlenmeyer flask containing 50mL of acetone, and add 16.5 g(0.15mol) NaBF ₄ , magnetically stirred at room temperature for 10 hours, filtered, rotovapped to remove the volatile acetone, and dried in vacuum to obtain 25.16g of a white solid compound represented by formula (Ib), yield 86.5%, mp53.2 ～53.6℃;

Example 3

This example provides a method for preparing a modified epoxy resin and a modified epoxy resin prepared by the method. The raw materials of the modified epoxy resin include: epoxy resin E-51 80g, hydrophobic vinyl containing Type hexagonal boron nitride nanosheets (M-BNNSs) 6g, methyl methacrylate (MAA) 13g, and butyl acrylate (BA) 7g. The solvent used in the preparation process was 25 g of n-butanol, the third solvent, and 4 g of dibenzoyl peroxide (BPO) was the initiator.

The preparation method specifically includes:

(a) Preparation of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups:

(1) Hexagonal boron nitride is modified by surface hydroxylation to prepare hydroxylated hexagonal boron nitride. The specific implementation is: adding 50g of hexagonal boron nitride (hBN purity ≥99%, particle size 2～5μm) to 1000ml Then add a pre-prepared 5mol/L sodium hydroxide aqueous solution to a three-necked reaction flask, and mechanically stir for 10 hours under oil bath heating at about 100°C. The resulting mixture is washed with distilled water several times until the filtrate is neutral. After drying, 49.5 g of hydroxylated hexagonal boron nitride (hBN-OH) is obtained;

(2) The hydroxylated hexagonal boron nitride prepared in step (1) is subjected to freeze-thaw expansion treatment to prepare expanded hydroxylated hexagonal boron nitride. The specific embodiment is: the hydroxylated hexagonal boron nitride prepared in step (1) (hBN-OH) The product is formulated into a distilled water solution with a mass fraction of 10%, placed in a freezer at about -25°C for 5 hours, and then thawed to room temperature. In this way, the freeze-thaw cycle is 6 times to obtain an expanded hydroxylated hexagonal nitride Boron (P-hBN-OH) 49.1g, the number of hydroxyl groups on the surface is determined to be 0.0209mmol/g;

(3) Take 25 g of the expanded hydroxylated hexagonal boron nitride (P-hBN-OH) prepared in step (2), and put 250 mL of cyclohexane into a 1000 mL three-necked flask with a stirrer and reflux trap, and heat to Reflux, the water in the system is gradually removed by the refluxing solvent. When there is no water in the reflux separator, the temperature is reduced to 80°C, and 237g of the compound represented by formula (Ia) prepared above is added, and the reactor is placed in ultrasonic In the washer, control the water temperature at about 70°C, ultrasonically stir the reaction for 24h, then add 12g of linoleic acid and 50mL of ethyl acetate, and then add nitrogen, heat to about 100°C, reflux for 4h, cool to 65°C, reduce pressure Suction filtration, the filter cake was washed twice with toluene/acetone (1:1 volume ratio) mixture, then filtered, and added to 500mL toluene/isopropanol mixture to form a micro-nano dispersion at a speed of 8000r/min Centrifugal treatment, take the upper suspension, filter and dry (140℃) to obtain the vinyl-containing hydrophobic hexagonal boron nitride nanosheets M-BNNSs (formula (IV-1)) 14.4g, the yield is 57.3% ；

[The calculation method of yield is:

: _M M-BNNSs is the mass g of hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) containing vinyl groups; W _P-BNOH is the mass g of expanded hydroxylated hexagonal boron nitride (P-hBN-OH); n _P-BNOH : the surface hydroxyl content of the expanded hydroxylated hexagonal boron nitride (P-hBN-OH) mmol/g; M _ma : the molecular weight of the modifier (unsaturated acid or unsaturated anhydride), in this example Oleic acid: 280.44 g/mol, the calculation method is the same in the following examples].

The TEM image of the measured product is shown in Figure 1(a)(b)(c). The TEM image of a single exfoliated M-BNNSs can be seen on the porous carbon grid, showing the transparent effect of a single layer of M-BNNSs, and Displaying a horizontal size of 2-3μm, using HRTEM (High Definition Transmission Electron Microscope) Figure 1(d) to measure the side curled superimposed image of a few layers of M-BNNSs. This curling is caused by the 200KV electron microscope test environment and can be clearly seen The number of BNNS curled layers is 7 layers, which proves that this application has obtained single-layer or few-layer M-BNNSs. As shown in Figure 2: A typical atomic force microscope (AFM) image of M-BNNSs deposited on a mica substrate from an ethanol/water dispersion, showing a flake height of 3nm, which also reveals the exfoliated M -The characteristics of BNNSs. The measured XRD pattern is the XRD comparison pattern of the original hexagonal boron nitride and the hydrophobic hexagonal boron nitride nanosheets M-BNNSs containing vinyl. The diffraction peaks (002), (100), (101) are shown in the figure. (102), (004), (104), (110), (112) are consistent with the XRD standard peaks of hexagonal boron nitride, which also proves that the hydrophobic hexagonal boron nitride nanosheets containing vinyl do not contain Other impurities. In addition, from the figure, we can see that the (002) peak has shifted to the small angle direction, and the peak is relatively enhanced. These all indicate that the modified hexagonal boron nitride (002) surface after peeling is more exposed, and the surface spacing has become Larger, indicating that the boron nitride has been well stripped.

The filtrate after the vacuum suction filtration is cooled to below 25°C and left to stand for 4 hours. The lower liquid (where the compound represented by formula (Ia) is located) can be used again for the next cycle after simple rotary evaporation. The tablet and catalyst are peeled off, so as to be reused; the upper layer after standing for layering is a mixed solvent, which can be recycled after being treated by vacuum distillation;

The structural formula of formula (IV-1) is as follows, which only shows the schematic structure of one hydroxyl group on the boron nitride nanosheets reacted with linoleic acid and covalently connected. Other hydroxyl groups on the boron nitride nanosheets can also be combined with linoleic acid. Covalent connection after reaction:

(b) Preparation of modified epoxy resin

(b-1) Mix epoxy resin E-51 with n-butanol and 1/4 of BPO uniformly, place them in a four-necked flask connected with a condensate pipe and nitrogen, and add the formula (IV-1) prepared above Hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) containing vinyl as shown, heated in an oil bath to 90°C for 30 minutes;

(b-2) The temperature is raised to about 110℃, and at the same time, the mixed monomer (MAA and BA) solution with 3/4BPO initiator dissolved in a constant pressure dropping funnel is added dropwise, and the solution is slowly dropped for about 30 minutes, and the reaction is kept warm after the dropping After 3-4 hours, the n-butanol is removed by vacuum distillation (recyclable) to obtain 108g of modified epoxy resin (Formula V-1). The synthetic route is shown as follows:

x, y, and z are independently integers between 1-25, and n is an integer selected from 0-10; specifically, the epoxy value of the E51 epoxy resin used above is 0.51, then the average The molecular weight should be 200/0.51=392.16;

Represents the average number of n. In the following examples, when E51 epoxy resin is used, n is the same;

The monomers MAA, BA and the vinyl-containing hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) represented by formula (IV-1) prepared above can also be copolymerized. The above is only exemplary in one of them. Active site graft copolymerization, to show that the method of this application can copolymerize the hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) containing vinyl groups represented by formula (IV-1) to epoxy resin molecules. The hybrid toughening modification of epoxy with inorganic boron nitride; at the same time, the modified epoxy resin represented by formula V-1 and the hydrophobic hexagonal boron nitride nanosheets containing vinyl groups represented by formula (Ⅳ-1) , MAA and BA are copolymerized and grafted onto the epoxy resin matrix in no particular order. Formula V-1 only provides an exemplary grafting method. Similarly, the following embodiments are all exemplary The schematic structures of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups and modified epoxy resins are given.

Example 4

This example provides a method for preparing a modified epoxy resin and a modified epoxy resin prepared by the method. The raw material of the epoxy resin includes: epoxy resin E-51 80g, hydrophobic hexagonal containing vinyl Boron nitride nanosheets (M-BNNSs) 6g, methyl methacrylate (MAA) 13g, and butyl acrylate (BA) 7g. Although the solvent used in the preparation process is 25 g of n-butanol, the third solvent, and the initiator is 4 g of dibenzoyl peroxide (BPO).

The preparation method specifically includes:

(a) Preparation of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups:

(1) Hexagonal boron nitride is modified by surface hydroxylation to prepare hydroxylated hexagonal boron nitride. The specific implementation is: adding 50g of hexagonal boron nitride (hBN purity ≥99%, particle size 2～5μm) to 1000ml Then add a pre-prepared 5mol/L sodium hydroxide aqueous solution to a three-necked reaction flask, and mechanically stir for 10 hours under oil bath heating at about 100°C. The resulting mixture is washed with distilled water several times until the filtrate is neutral. After drying, 49.5 g of hydroxylated hexagonal boron nitride (hBN-OH) is obtained;

(2) The hydroxylated hexagonal boron nitride prepared in step (1) is subjected to freeze-thaw expansion treatment to prepare expanded hydroxylated hexagonal boron nitride. The specific embodiment is: the hydroxylated hexagonal boron nitride prepared in step (1) (hBN-OH) The product is formulated into a distilled water solution with a mass fraction of 10%, placed in a freezer at about -25°C for 5 hours, and then thawed to room temperature. In this way, the freeze-thaw cycle is 6 times to obtain an expanded hydroxylated hexagonal nitride Boron (P-hBN-OH) 49.1g, the number of hydroxyl groups on the surface is determined to be 0.0209mmol/g;

(3) Take 25 g of the expanded hydroxylated hexagonal boron nitride (P-hBN-OH) prepared in step (2), and put 250 mL of cyclohexane into a 1000 mL three-necked flask with a stirrer and reflux trap, and heat to Reflux, the water in the system is gradually removed by the refluxing solvent. When there is no water in the reflux separator, the temperature is lowered to 80°C, 218g of the compound represented by formula (Ib) prepared above is added, and the reactor is placed in ultrasonic In the washer, control the water temperature at about 70°C, ultrasonically stir the reaction for 24h, then add 12g of linoleic acid and 50mL of ethyl acetate, and then add nitrogen, heat to about 100°C, reflux for 4h, cool to 65°C, reduce pressure Suction filtration, the filter cake was washed twice with toluene/acetone (1:1 volume ratio) mixture, then filtered, and added to 500mL toluene/isopropanol mixture to form a micro-nano dispersion at a speed of 8000r/min Centrifugal treatment, take the upper suspension, filter and dry (140°C) to obtain the vinyl-containing hydrophobic hexagonal boron nitride nanosheets M-BNNSs formula (IV-1) 14.5g, the yield is 57.7%;

It only shows the schematic structure of one hydroxyl group on the boron nitride nanosheet reacted with linoleic acid and covalently connected. Other hydroxyl groups on the boron nitride nanosheet can also be covalently connected after reacting with linoleic acid;

(b) Preparation of modified epoxy resin:

(b-1) Mix epoxy resin E-51 with n-butanol and 1/4 of BPO uniformly, place them in a four-necked flask connected with a condensate pipe and nitrogen, and add the formula (IV-1) prepared above Hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) containing vinyl as shown, heated in an oil bath to 90°C for 30 minutes;

(b-2) The temperature is raised to about 110℃, and at the same time, the mixed monomer (MAA and BA) solution with 3/4BPO initiator dissolved in a constant pressure dropping funnel is added dropwise, and the solution is slowly added dropwise for about 3 0min, and the temperature is kept after dripping. After reacting for 3-4 hours, then distilling under reduced pressure to remove the n-butanol (recyclable) to obtain 108.1 g of the modified epoxy resin.

Example 5

This example provides a method for preparing a modified epoxy resin and a modified epoxy resin prepared by the method. The raw material of the modified epoxy resin includes: epoxy resin E-44 85g, hydrophobic vinyl containing Type hexagonal boron nitride nanosheets (M-BNNSs) 6g, methyl methacrylate (MAA) 13g, and butyl acrylate (BA) 7g. The solvent used in the preparation process was 25 g of n-butanol, the third solvent, and 4 g of dibenzoyl peroxide (BPO) was the initiator.

The preparation method specifically includes:

(a) Preparation of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups:

(1) Hexagonal boron nitride is modified by surface hydroxylation to prepare hydroxylated hexagonal boron nitride. The specific implementation is: adding 50g of hexagonal boron nitride (hBN purity ≥99%, particle size 2～5μm) to 1000ml Then add a pre-prepared 5mol/L sodium hydroxide aqueous solution to a three-necked reaction flask, and mechanically stir for 10 hours under oil bath heating at about 100°C. The resulting mixture is washed with distilled water several times until the filtrate is neutral. After drying, 49.5 g of hydroxylated hexagonal boron nitride (hBN-OH) is obtained;

(2) The hydroxylated hexagonal boron nitride prepared in step (1) is subjected to freeze-thaw expansion treatment to prepare expanded hydroxylated hexagonal boron nitride. The specific embodiment is: the hydroxylated hexagonal boron nitride prepared in step (1) (hBN-OH) The product is formulated into a distilled water solution with a mass fraction of 10%, placed in a freezer at about -25°C for 5 hours, and then thawed to room temperature. In this way, the freeze-thaw cycle is 6 times to obtain an expanded hydroxylated hexagonal nitride Boron (P-hBN-OH) 49.1g, the number of hydroxyl groups on the surface is determined to be 0.0209mmol/g;

(3) Take 25 g of the expanded hydroxylated hexagonal boron nitride (P-hBN-OH) prepared in step (2), and put 250 mL of cyclohexane into a 1000 mL three-necked flask with a stirrer and reflux trap, and heat to Reflux, the water in the system is gradually removed by the refluxing solvent. When there is no water in the reflux separator, the temperature is reduced to 80°C, and 237g of the compound represented by formula (Ia) prepared above is added, and the reactor is placed in ultrasonic In the washer, control the water temperature at about 70°C, ultrasonically stir the reaction for 24h, then add 4g of methacrylic acid and 50mL of ethyl acetate, and then add nitrogen, heat to about 100°C, reflux for 4h, cool to 65°C, reduce pressure Suction filtration, the filter cake was washed twice with toluene/acetone (1:1 volume ratio) mixture, then filtered, and added to 500mL toluene/isopropanol mixture to form a micro-nano dispersion at a speed of 8000r/min Centrifugal treatment, take the upper suspension, filter and dry (140°C) to obtain the vinyl-containing hydrophobic hexagonal boron nitride nanosheet M-BNNSs (formula (IV-2)) 14.3g, the yield is 57.1% ；

The structural formula of formula (IV-2) is as follows. It only shows the schematic structure of a hydroxyl group on the boron nitride nanosheet reacted with methacrylic acid and covalently connected. Other hydroxyl groups on the boron nitride nanosheet can also be connected with methacrylic acid. Covalent connection after reaction:

(b) Preparation of modified epoxy resin:

(b-1) Mix epoxy resin E-44 with n-butanol and 1/4 of BPO uniformly, place them in a four-necked flask connected with a condensed water pipe and nitrogen, and add the formula (IV-2) prepared above Hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) containing vinyl as shown, heated in an oil bath to 90°C for 30 minutes;

(b-2) The temperature is raised to about 110℃, and at the same time, the mixed monomer (MAA and BA) solution with 3/4BPO initiator dissolved in a constant pressure dropping funnel is added dropwise, and the solution is slowly added dropwise for about 3 0min, and the temperature is kept after dripping. After reacting for 3-4 hours, then distilling under reduced pressure to remove the n-butanol (recyclable) to obtain 113.5 g of the modified epoxy resin (Formula V-2). The synthetic route is as follows:

x, y, z are independently numbers between 1-25, n is an integer selected from 0-10; the epoxy value of the E44 epoxy resin used above is 0.44, then the average molecular weight of the epoxy resin should be 200/0.44=454.55;

Represents the average number of n. In the following examples, n is the same when E44 epoxy resin is used.

Example 6

This example provides a method for preparing a modified epoxy resin and a modified epoxy resin prepared by the method. The raw material of the modified epoxy resin includes: epoxy resin E-44 85g, hydrophobic vinyl containing Type hexagonal boron nitride nanosheets (M-BNNSs) 6g, methyl methacrylate (MAA) 13g, and butyl acrylate (BA) 7g. The solvent used in the preparation process was 25 g of n-butanol, the third solvent, and 4 g of dibenzoyl peroxide (BPO) was the initiator.

The preparation method specifically includes:

(a) Preparation of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups:

(1) Hexagonal boron nitride is modified by surface hydroxylation to prepare hydroxylated hexagonal boron nitride. The specific implementation is: adding 50g of hexagonal boron nitride (hBN purity ≥99%, particle size 2～5μm) to 1000ml Then add a pre-prepared 5mol/L sodium hydroxide aqueous solution to a three-necked reaction flask, and mechanically stir for 10 hours under oil bath heating at about 100°C. The resulting mixture is washed with distilled water several times until the filtrate is neutral. After drying, 49.5 g of hydroxylated hexagonal boron nitride (hBN-OH) is obtained;

(2) The hydroxylated hexagonal boron nitride prepared in step (1) is subjected to freeze-thaw expansion treatment to prepare expanded hydroxylated hexagonal boron nitride. The specific embodiment is: the hydroxylated hexagonal boron nitride prepared in step (1) (hBN-OH) The product is formulated into a distilled water solution with a mass fraction of 10%, placed in a freezer at about -25°C for 5 hours, and then thawed to room temperature. In this way, the freeze-thaw cycle is 6 times to obtain an expanded hydroxylated hexagonal nitride Boron (P-hBN-OH) 49.1g, the number of hydroxyl groups on the surface is determined to be 0.0209mmol/g;

(3) Take 25 g of the expanded hydroxylated hexagonal boron nitride (P-hBN-OH) prepared in step (2), and put 250 mL of cyclohexane into a 1000 mL three-necked flask with a stirrer and reflux trap, and heat to Reflux, the water in the system is gradually removed by the refluxing solvent. When there is no water in the reflux separator, the temperature is lowered to 80°C, 218g of the compound represented by formula (Ib) prepared above is added, and the reactor is placed in ultrasonic In the washer, control the water temperature at about 70°C, ultrasonically stir the reaction for 24h, then add 4g of methacrylic acid and 50mL of ethyl acetate, and then add nitrogen, heat to about 100°C, reflux for 4h, cool to 65°C, reduce pressure Suction filtration, the filter cake was washed twice with toluene/acetone (1:1 volume ratio) mixture, then filtered, and added to 500mL toluene/isopropanol mixture to form a micro-nano dispersion at a speed of 8000r/min Centrifugal treatment, take the upper suspension, filter and dry (140℃) to obtain the vinyl-containing hydrophobic hexagonal boron nitride nanosheet M-BNNSs (formula (IV-2)) 14.5g, the yield is 57.9% ；

The structural formula of formula (IV-2) is as follows. It only shows the schematic structure of a hydroxyl group on the boron nitride nanosheet reacted with methacrylic acid and covalently connected. Other hydroxyl groups on the boron nitride nanosheet can also be connected with methacrylic acid. Covalent connection after reaction:

(b) Preparation of modified epoxy resin:

(b-1) Mix epoxy resin E-44 with n-butanol and 1/4 of BPO uniformly, place them in a four-necked flask connected with a condensed water pipe and nitrogen, and add the formula (IV-2) prepared above Hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) containing vinyl as shown, heated in an oil bath to 90°C for 30 minutes;

(b-2) The temperature is raised to about 110℃, and at the same time, the mixed monomer (MAA and BA) solution with 3/4BPO initiator dissolved in a constant pressure dropping funnel is added dropwise, and the solution is slowly added dropwise for about 3 0min, and the temperature is kept after dripping. After reacting for 3-4 hours, and then distilling under reduced pressure to remove the n-butanol (recyclable), 113.7 g of the modified epoxy resin is obtained.

Example 7

This example provides a method for preparing a modified epoxy resin and a modified epoxy resin prepared by the method. The raw materials of the modified epoxy resin include: epoxy resin E-51 80g, hydrophobic vinyl containing Type hexagonal boron nitride nanosheets (M-BNNSs) 6g, methyl methacrylate (MAA) 13g, and butyl acrylate (BA) 7g. The solvent used in the preparation process was 25 g of n-butanol, the third solvent, and 4 g of dibenzoyl peroxide (BPO) was the initiator.

The preparation method specifically includes:

(a) Preparation of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups:

(1) Hexagonal boron nitride is modified by surface hydroxylation to prepare hydroxylated hexagonal boron nitride. The specific implementation is: adding 50g of hexagonal boron nitride (hBN purity ≥99%, particle size 2～5μm) to 1000ml Then add a pre-prepared 5mol/L sodium hydroxide aqueous solution to a three-necked reaction flask, and mechanically stir for 10 hours under oil bath heating at about 100°C. The resulting mixture is washed with distilled water several times until the filtrate is neutral. After drying, 49.5 g of hydroxylated hexagonal boron nitride (hBN-OH) is obtained;

(2) The hydroxylated hexagonal boron nitride prepared in step (1) is subjected to freeze-thaw expansion treatment to prepare expanded hydroxylated hexagonal boron nitride. The specific embodiment is: the hydroxylated hexagonal boron nitride prepared in step (1) (hBN-OH) The product is formulated into a distilled water solution with a mass fraction of 10%, placed in a freezer at about -25°C for 5 hours, and then thawed to room temperature. In this way, the freeze-thaw cycle is 6 times to obtain an expanded hydroxylated hexagonal nitride Boron (P-hBN-OH) 49.1g, the number of hydroxyl groups on the surface is determined to be 0.0209mmol/g;

(3) Take 25 g of the expanded hydroxylated hexagonal boron nitride (P-hBN-OH) prepared in step (2), and put 250 mL of cyclohexane into a 1000 mL three-necked flask with a stirrer and reflux trap, and heat to Reflux, the water in the system is gradually removed by the refluxing solvent. When there is no water in the reflux separator, the temperature is reduced to 80°C, and 237g of the compound represented by formula (Ia) prepared above is added, and the reactor is placed in ultrasonic In the washer, control the water temperature at about 70°C, ultrasonically stir the reaction for 24 hours, then add 5 g of itaconic anhydride and 50 mL of ethyl acetate, and then add nitrogen, heat to about 100°C, reflux for 4 hours, cool to 65°C, and reduce pressure Suction filtration, the filter cake was washed twice with toluene/acetone (1:1 volume ratio) mixture, then filtered, and added to 500mL toluene/isopropanol mixture to form a micro-nano dispersion at a speed of 8000r/min Centrifugal treatment, take the upper suspension, filter and dry (140°C) to obtain 14.8 g of the vinyl-containing hydrophobic hexagonal boron nitride nanosheet M-BNNSs (formula (IV-3)), with a yield of 59.1% ; The structural formula of formula (IV-3) is as follows, which only shows the schematic structure of a hydroxyl group on the boron nitride nanosheets reacting with itaconic anhydride, and the other hydroxyl groups on the boron nitride nanosheets can also be connected with itaconic Covalent connection after acid anhydride reaction:

(b) Preparation of modified epoxy resin:

(b-1) Mix epoxy resin (E-51), n-butanol and 1/4 of BPO uniformly, place them in a four-necked flask connected with a condensed water pipe and nitrogen, and add the formula (Ⅳ-3) prepared above ) Shows the hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) containing vinyl, heated in an oil bath to 90°C for 30 minutes;

(b-2) The temperature is raised to about 110℃, and at the same time, the mixed monomer (MAA and BA) solution with 3/4BPO initiator dissolved in a constant pressure dropping funnel is added dropwise, and the solution is slowly added dropwise for about 3 0min, and the temperature is kept after dripping. After reacting for 3-4 hours, then distilling under reduced pressure to remove the n-butanol (recyclable) to obtain 108.9 g of the modified epoxy resin (Formula V-3). The synthetic route is as follows:

x, y, and z are independently numbers between 0-25 and none of them are 0, and n is an integer selected from 0-10;

Example 8

This example provides a method for preparing a modified epoxy resin and a modified epoxy resin prepared by the method. The raw materials of the modified epoxy resin include: epoxy resin E-51 80g, hydrophobic vinyl containing Type hexagonal boron nitride nanosheets (M-BNNSs) 6g, methyl methacrylate (MAA) 13g, and butyl acrylate (BA) 7g. The solvent used in the preparation process was 25 g of n-butanol, the third solvent, and 4 g of dibenzoyl peroxide (BPO) was the initiator.

The preparation method specifically includes:

(a) Preparation of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups:

(1) Hexagonal boron nitride is modified by surface hydroxylation to prepare hydroxylated hexagonal boron nitride. The specific implementation is: adding 50g of hexagonal boron nitride (hBN purity ≥99%, particle size 2～5μm) to 1000ml Then add a pre-prepared 5mol/L sodium hydroxide aqueous solution to a three-necked reaction flask, and mechanically stir for 10 hours under oil bath heating at about 100°C. The resulting mixture is washed with distilled water several times until the filtrate is neutral. After drying, 49.5 g of hydroxylated hexagonal boron nitride (hBN-OH) is obtained;

(2) The hydroxylated hexagonal boron nitride prepared in step (1) is subjected to freeze-thaw expansion treatment to prepare expanded hydroxylated hexagonal boron nitride. The specific embodiment is: the hydroxylated hexagonal boron nitride prepared in step (1) (hBN-OH) The product is formulated into a distilled water solution with a mass fraction of 10%, placed in a freezer at about -25°C for 5 hours, and then thawed to room temperature. In this way, the freeze-thaw cycle is 6 times to obtain an expanded hydroxylated hexagonal nitride Boron (P-hBN-OH) 49.1g, the number of hydroxyl groups on the surface is determined to be 0.0209mmol/g;

(3) Take 25 g of the expanded hydroxylated hexagonal boron nitride (P-hBN-OH) prepared in step (2), and put 250 mL of cyclohexane into a 1000 mL three-necked flask with a stirrer and reflux trap, and heat to Reflux, the water in the system is gradually removed by the refluxing solvent. When there is no water in the reflux separator, the temperature is lowered to 80°C, 218g of the compound represented by formula (Ib) prepared above is added, and the reactor is placed in ultrasonic In the washer, control the water temperature at about 70°C, ultrasonically stir the reaction for 24 hours, then add 5 g of itaconic anhydride and 50 mL of ethyl acetate, and then add nitrogen, heat to about 100°C, reflux for 4 hours, cool to 65°C, and reduce pressure Suction filtration, the filter cake was washed twice with toluene/acetone (1:1 volume ratio) mixture, then filtered, and added to 500mL toluene/isopropanol mixture to form a micro-nano dispersion at a speed of 8000r/min Centrifugal treatment, take the upper suspension, filter and dry (140°C) to obtain 14.7 g of the vinyl-containing hydrophobic hexagonal boron nitride nanosheet M-BNNSs (formula (IV-3)), with a yield of 58.7% ; The structural formula of formula (IV-3) is as follows, which only shows the schematic structure of a hydroxyl group on the boron nitride nanosheets reacting with itaconic anhydride, and the other hydroxyl groups on the boron nitride nanosheets can also be connected with itaconic Covalent connection after acid anhydride reaction:

(b) Preparation of modified epoxy resin:

(b-1) Mix epoxy resin (E-51), n-butanol and 1/4 of BPO uniformly, place them in a four-necked flask connected with a condensed water pipe and nitrogen, and add the formula (Ⅳ-3) prepared above ) Shows the hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) containing vinyl, heated in an oil bath to 90°C for 30 minutes;

(b-2) The temperature is raised to about 110℃, and at the same time, the mixed monomer (MAA and BA) solution with 3/4BPO initiator dissolved in a constant pressure dropping funnel is added dropwise, and the solution is slowly added dropwise for about 3 0min, and the temperature is kept after dripping. After reacting for 3-4 hours, then distilling under reduced pressure to remove the n-butanol (recyclable) to obtain 108.8 g of the modified epoxy resin.

Example 9

This example provides a method for preparing a modified epoxy resin and a modified epoxy resin prepared by the method. The raw material of the modified epoxy resin includes: epoxy resin E-44 85g, hydrophobic vinyl containing Type hexagonal boron nitride nanosheets (M-BNNSs) 6g, methyl methacrylate (MAA) 13g, and butyl acrylate (BA) 7g. The solvent used in the preparation process was 25 g of n-butanol, the third solvent, and 4 g of dibenzoyl peroxide (BPO) was the initiator.

The preparation method specifically includes:

(a) Preparation of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups:

(1) Hexagonal boron nitride is modified by surface hydroxylation to prepare hydroxylated hexagonal boron nitride. The specific implementation is: adding 50g of hexagonal boron nitride (hBN purity ≥99%, particle size 2～5μm) to 1000ml Then add a pre-prepared 5mol/L sodium hydroxide aqueous solution to a three-necked reaction flask, and mechanically stir for 10 hours under oil bath heating at about 100°C. The resulting mixture is washed with distilled water several times until the filtrate is neutral. After drying, 49.5 g of hydroxylated hexagonal boron nitride (hBN-OH) is obtained;

(2) The hydroxylated hexagonal boron nitride prepared in step (1) is subjected to freeze-thaw expansion treatment to prepare expanded hydroxylated hexagonal boron nitride. The specific embodiment is: the hydroxylated hexagonal boron nitride prepared in step (1) (hBN-OH) The product is formulated into a distilled water solution with a mass fraction of 10%, placed in a freezer at about -25°C for 5 hours, and then thawed to room temperature. In this way, the freeze-thaw cycle is 6 times to obtain an expanded hydroxylated hexagonal nitride Boron (P-hBN-OH) 49.1g, the number of hydroxyl groups on the surface is determined to be 0.0209mmol/g;

(3) Take 25 g of the expanded hydroxylated hexagonal boron nitride (P-hBN-OH) prepared in step (2), and put 250 mL of cyclohexane into a 1000 mL three-necked flask with a stirrer and reflux trap, and heat to Reflux, the water in the system is gradually removed by the refluxing solvent. When there is no water in the reflux separator, the temperature is reduced to 80°C, and 237g of the compound represented by formula (Ia) prepared above is added, and the reactor is placed in ultrasonic In the washer, control the water temperature at about 70°C, ultrasonically stir the reaction for 24h, then add 4.5g of maleic anhydride and 50mL of ethyl acetate, pour in nitrogen, heat to about 100°C, reflux for 4h, and cool down to 65°C , Vacuum filtration, the filter cake was washed twice with toluene/acetone (1:1 volume ratio) mixture, and then filtered, added to 500mL toluene/isopropanol mixture to form a micro-nano dispersion, at 8000r/ After centrifugation at a rotation speed of 1 min, the upper suspension was filtered and dried (140°C) to obtain the vinyl-containing hydrophobic hexagonal boron nitride nanosheets M-BNNSs (formula (IV-4)) 14.8 g, yield Is 59.1%;

The structural formula of formula (IV-4) is as follows. It only shows the schematic structure of a hydroxyl group on the boron nitride nanosheet reacted with maleic anhydride and covalently connected. The other hydroxyl groups on the boron nitride nanosheet can also be connected with the cis Covalent connection after reaction of butenedioic anhydride:

(b) Preparation of modified epoxy resin:

(b-1) Mix epoxy resin E-44, n-butanol and 1/4 of BPO uniformly, place them in a four-necked flask connected with a condensed water pipe and nitrogen, and add the formula (IV-4) prepared above Hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) containing vinyl as shown, heated in an oil bath to 90°C for 30 minutes;

(b-2) The temperature is raised to about 110℃, and at the same time, the mixed monomer (MAA and BA) solution with 3/4BPO initiator dissolved in a constant pressure dropping funnel is added dropwise, and the solution is slowly added dropwise for about 3 0min, and the temperature is kept after dripping. After reacting for 3-4 hours, then distilling under reduced pressure to remove n-butanol (recyclable) to obtain 113.9 g of the modified epoxy resin (Formula V-4). The synthetic route is shown as follows:

x, y, and z are independently numbers between 1-25, and n is an integer selected from 0-10.

Example 10

This example provides a method for preparing a modified epoxy resin and a modified epoxy resin prepared by the method. The raw material of the modified epoxy resin includes: epoxy resin E-44 85g, hydrophobic vinyl containing Type hexagonal boron nitride nanosheets (M-BNNSs) 6g, methyl methacrylate (MAA) 13g, and butyl acrylate (BA) 7g. The solvent used in the preparation process was 25 g of n-butanol, the third solvent, and 4 g of dibenzoyl peroxide (BPO) was the initiator.

The preparation method specifically includes:

(a) Preparation of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups:

(1) Hexagonal boron nitride is modified by surface hydroxylation to prepare hydroxylated hexagonal boron nitride. The specific implementation is: adding 50g of hexagonal boron nitride (hBN purity ≥99%, particle size 2～5μm) to 1000ml Then add a pre-prepared 5mol/L sodium hydroxide aqueous solution to a three-necked reaction flask, and mechanically stir for 10 hours under oil bath heating at about 100°C. The resulting mixture is washed with distilled water several times until the filtrate is neutral. After drying, 49.5 g of hydroxylated hexagonal boron nitride (hBN-OH) is obtained;

(2) The hydroxylated hexagonal boron nitride prepared in step (1) is subjected to freeze-thaw expansion treatment to prepare expanded hydroxylated hexagonal boron nitride. The specific embodiment is: the hydroxylated hexagonal boron nitride prepared in step (1) (hBN-OH) The product is formulated into a distilled water solution with a mass fraction of 10%, placed in a freezer at about -25°C for 5 hours, and then thawed to room temperature. In this way, the freeze-thaw cycle is 6 times to obtain an expanded hydroxylated hexagonal nitride Boron (P-hBN-OH) 49.1g, the number of hydroxyl groups on the surface is determined to be 0.0209mmol/g;

(3) Take 25 g of the expanded hydroxylated hexagonal boron nitride (P-hBN-OH) prepared in step (2), and put 250 mL of cyclohexane into a 1000 mL three-necked flask with a stirrer and reflux trap, and heat to Reflux, the water in the system is gradually removed by the refluxing solvent. When there is no water in the reflux separator, the temperature is lowered to 80°C, 218g of the compound represented by formula (Ib) prepared above is added, and the reactor is placed in ultrasonic In the washer, control the water temperature at about 70°C, ultrasonically stir the reaction for 24h, then add 4.5g of maleic anhydride and 50mL of ethyl acetate, pour in nitrogen, heat to about 100°C, reflux for 4h, and cool down to 65°C , Vacuum filtration, the filter cake was washed twice with toluene/acetone (1:1 volume ratio) mixture, and then filtered, added to 500mL toluene/isopropanol mixture to form a micro-nano dispersion, at 8000r/ After centrifugation at a rotation speed of 1 min, the upper suspension was filtered and dried (140°C) to obtain the vinyl-containing hydrophobic hexagonal boron nitride nanosheets M-BNNSs (formula (IV-4)) 14.7 g, yield 58.7%;

The structural formula of formula (IV-4) is as follows. It only shows the schematic structure of a hydroxyl group on the boron nitride nanosheet reacted with maleic anhydride and covalently connected. The other hydroxyl groups on the boron nitride nanosheet can also be connected with the cis Covalent connection after reaction of butenedioic anhydride:

(b) Preparation of modified epoxy resin:

(b-1) Mix epoxy resin (E-44), n-butanol and 1/4 of BPO uniformly, place them in a four-necked flask connected with a condensed water pipe and nitrogen, and add the formula (Ⅳ-4) prepared above ) Shows the hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) containing vinyl, heated in an oil bath to 90°C for 30 minutes;

(b-2) The temperature is raised to about 110℃, and at the same time, the mixed monomer (MAA and BA) solution with 3/4BPO initiator dissolved in a constant pressure dropping funnel is added dropwise, and the solution is slowly added dropwise for about 3 0min, and the temperature is kept after dripping. After reacting for 3-4 hours, and then distilling under reduced pressure to remove the n-butanol (which can be recycled), 113.8 g of the modified epoxy resin is obtained. Comparative example 1

This example provides a modified epoxy resin. Its raw materials include: epoxy resin E-44 85g, hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) 6g, methyl methacrylate (MAA) 13g, butyl acrylate Ester (BA) 7g. The solvent used in the preparation process was 25 g of n-butanol, the third solvent, and 4 g of dibenzoyl peroxide (BPO) was the initiator.

It is prepared by the following method:

(1) Preparation of hydrophobic hexagonal boron nitride nanosheets:

(1) Preparation of hydroxylated hexagonal boron nitride, the specific implementation is: add 50g hexagonal boron nitride (hBN purity ≥99%, particle size 2-5μm) into a 1000ml three-necked reaction flask, and then add the pre-prepared In a 5mol/L sodium hydroxide aqueous solution, mechanically stirred for 10 hours under oil bath heating at about 100°C. The resulting mixture was washed with distilled water several times until the filtrate became neutral. After drying, hydroxylated hexagonal boron nitride (hBN -OH) 49.5g;

(2) Preparation of expanded hydroxylated hexagonal boron nitride, the specific implementation is: the hydroxylated hexagonal boron nitride (hBN-OH) product prepared in step (1) is formulated into a distilled aqueous solution with a mass fraction of 10%, and put Put it in a freezer at about -25°C for 5h, then thaw to room temperature, and then freeze-thaw cycles for 6 times to obtain 49.1g of expanded hydroxylated hexagonal boron nitride (P-hBN-OH). The number of hydroxyl groups on the surface is determined to be 0.0209mmol/g;

(3) Take 25g of the expanded hydroxylated hexagonal boron nitride (P-hBN-OH) prepared in (2), add 250mL of mixed solvent (toluene/cyclohexane=1:1) into 1000mL three ports with agitator In the flask, heat to reflux, and the water in the system is gradually removed by the refluxing solvent. When there is no water in the reflux trap, the temperature is reduced to 80°C, and polyethylene glycol is added.

86g, and put the reactor in an ultrasonic cleaner, control the water temperature at about 70°C, ultrasonically stir the reaction for 24h, then lower the temperature to 65°C, precipitate for 30min, and extract the solvent under reduced pressure;

(4) Then add 12g of linoleic acid to the obtained precipitate, add 100mL of mixed solvent (toluene/cyclohexane=1:1), pour in nitrogen, heat up to about 120℃, reflux for 8h, and cool to 65℃ , Vacuum filtration, the filter cake was washed twice with toluene/acetone (1:1 volume ratio) mixture, and then filtered, added to 500mL toluene/isopropanol mixture to form a micro-nano dispersion, at 8000r/ After centrifugation at a speed of 1 min, the upper suspension was filtered and dried (140°C) to obtain 9.0 g of hydrophobic hexagonal boron nitride nanosheets (M-BNNSs) with a yield of 35.8%;

(2) Preparation of modified epoxy resin:

(1) Mix the epoxy resin E-44 with n-butanol and 1/4 of the BPO uniformly, place them in a four-necked flask connected with a condensate pipe and nitrogen, and add the hydrophobic hexagonal boron nitride nanosheets prepared above. Heat the oil bath to 90℃ for 30min;

(2) The temperature is raised to about 110℃, and at the same time, the mixed monomer (MAA and BA) solution with 3/4BPO initiator dissolved in a constant pressure dropping funnel is added dropwise, and slowly dripped for about 3 0min. After the dripping is completed, the reaction is kept warm and 3 -4h, and then distill under reduced pressure to remove the n-butanol (recyclable) to obtain 113.6g of modified epoxy resin.

The difference between Comparative Example 1 and the present application is that the compound represented by the formula (I) of the present application is not used for exfoliation and esterification, resulting in the need for two-step reaction and double the synthesis time. The obtained hydrophobic hexagonal boron nitride nanosheet product contains unmodified hexagonal boron nitride nanosheets and is not easy to separate. Therefore, the prepared modified epoxy resin contains independently unmodified hexagonal boron nitride nanosheets, which affects the performance of the dipping paint product.

Comparative example 2

Directly use commercially available hexagonal boron nitride nanosheets. The raw materials of modified epoxy resin include: epoxy resin E-44 85g, commercially available hexagonal boron nitride nanosheets (M-BNNSs) 6g, methacrylic acid Methyl ester (MAA) 13g, butyl acrylate (BA) 7g. The solvent used in the preparation process was 25 g of n-butanol, the third solvent, and 4 g of dibenzoyl peroxide (BPO) was the initiator.

The preparation method specifically includes:

(1) Mix epoxy resin E-44, n-butanol and 1/4 of BPO uniformly, place them in a four-necked flask connected with a condensed water tube and nitrogen, and add commercially available hexagonal boron nitride nanosheets (M- BNNSs), the oil bath is heated to 90℃ for 30min;

(2) The temperature is raised to about 110℃, and at the same time, the mixed monomer (MAA and BA) solution with 3/4BPO initiator dissolved in a constant pressure dropping funnel is added dropwise, and slowly dripped for about 3 0min. After the dripping is completed, the reaction is kept warm and 3 -4h, then vacuum distillation to remove the n-butanol (recyclable) to obtain 113.8g of modified epoxy resin.

The difference between Comparative Example 2 and this application is that commercially available boron nitride nanosheets are directly doped into the acrylic grafted epoxy resin system, because the unmodified boron nitride nanosheets and epoxy resin phase The capacitance is poor, therefore, the thermal conductivity, electrical properties and adhesion of the dipping paint are far lower than the application.

Examples 11-18 and application examples 1-2

The embodiments provide an insulating impregnating varnish, which includes a matrix resin, a diluent, and a curing agent. The matrix resin is prepared by the following method: firstly, the modified epoxy resin, xylene of organosilicon alcohol with silanol The solution (the mass fraction of organosilanol is 50%) is added to the reactor, the temperature is slowly raised to 150±3℃, the reflux reaction is 45min, the solvent is gradually removed until the solid content reaches 85%, the catalyst cobalt naphthenate is added, and the water is continued to be separated The reaction is refluxed until the 65% wt viscosity reaches 90sec (Tu 4# cup, 25°C), and finally the temperature is reduced to 120±3°C, the solvent in the reaction system is removed by vacuum distillation, and the matrix resin is obtained by filtration.

Preparation of insulating impregnating varnish: The matrix resin prepared above, the diluent and the curing agent are mixed and stirred at room temperature for 60 minutes to prepare.

The organosilicon alcohol with silanol in the following is selected from TH-1# (R/Si=1.50, Ph/R=0.43, Vi mass parts %=4.1), Suzhou Taihu Electric New Materials Co., Ltd., Suzhou Taihu TH-2#(R/Si=1.58, Ph/R=0.35, Vi mass parts%=0.6) of Diangong New Material Co., Ltd., TH-3#(R/Si=1.50) of Suzhou Taihu Electric New Material Co., Ltd. , Ph/R=0.35, Vi mass parts %=3.2), both can be prepared according to the method described in ZL201310090271.6.

The initial raw materials and amounts used in Examples 11-18 and Application Examples 1-2 are shown in Table 1 below:

Table 1

Performance Testing

The insulating dipping varnishes obtained in the foregoing Examples 11-18 and Comparative Examples 1-2 were subjected to the following performance tests (curing process conditions of the performance test sample: 140°C/2h+170°C/10h), see Table 2 for details.

Table 2

The above embodiments are only to illustrate the technical ideas and features of this application, and their purpose is to enable those familiar with this technology to understand the content of this application and implement it accordingly, and cannot limit the scope of protection of this application. Equivalent changes or modifications made to the spirit and substance shall be covered by the scope of protection of this application.

Claims (10)

1. An insulating impregnating varnish, comprising a matrix resin, a diluent and a curing agent, characterized in that the matrix resin is made by the condensation reaction of a modified epoxy resin and a silicone alcohol The raw materials include epoxy resin, vinyl monomers containing ester groups, and hydrophobic hexagonal boron nitride nanosheets containing vinyl groups, and the modified epoxy resin is made by the polymerization reaction between the epoxy resin and the remaining raw materials Wherein, the hydrophobic hexagonal boron nitride nanosheets containing vinyl are prepared by the following method:

   (1) Surface hydroxylation modification of hexagonal boron nitride to prepare hydroxylated hexagonal boron nitride;

   (2) subjecting the hydroxylated hexagonal boron nitride prepared in step (1) to freeze-thaw expansion treatment to prepare expanded hydroxylated hexagonal boron nitride;

   (3) The expanded hydroxylated hexagonal boron nitride prepared in step (2) and the compound represented by formula (I) are mixed and stirred in the first solvent to obtain a first mixed solution, and then added to the obtained first mixed solution Adding unsaturated acid and/or unsaturated acid anhydride and a second solvent to react to prepare the hydrophobic hexagonal boron nitride nanosheets containing vinyl groups;

   

   Wherein, R ₀ is a C _1-6 alkyl group.
2. The insulating dipping varnish according to claim 1, wherein the vinyl monomer containing an ester group is one or a combination of one or more selected from the compounds represented by formula (II):

   

   In the formula, R ₁ is a C _1-10 alkyl group, R ₂ and R ₃ are each independently hydrogen or a C _1-10 alkyl group; more preferably, the vinyl monomer containing an ester group is selected from At least two of the compounds represented by formula (II).
3. The insulating impregnating varnish according to claim 1, wherein the epoxy resin is a bisphenol epoxy resin, and the bisphenol epoxy resin is one selected from the group consisting of compounds represented by formula (III) Kind or combination of many kinds:

   

   (III), where: R ₄ is -C(CH ₃ ) ₂ -, -CH ₂ -or -S(O) ₂ -, and n is an integer selected from 0-10.
4. The insulating dipping varnish of claim 1, wherein in the process of preparing the vinyl-containing hydrophobic hexagonal boron nitride nanosheets, the epoxy resin and the vinyl-containing hydrophobic hexagonal nitrogen The feed mass ratio of the boron oxide nanosheets and the ester group-containing vinyl monomer is 1:0.05-0.1:0.15-0.4; and/or the polymerization reaction is carried out at a temperature of 100-120°C.
5. The insulating impregnating varnish according to claim 1, wherein in step (1), the hydroxylated hexagonal boron nitride is prepared by the following method: mixing hexagonal boron nitride and sodium hydroxide aqueous solution at a temperature of 90 ~ Stir and react at 150°C to prepare; and/or, in step (2), the operation of the freeze-thaw swelling treatment is: the hydroxylated hexagonal boron nitride prepared in step (1) is formulated into an aqueous solution, and the resulting aqueous solution Frozen at the first set temperature, and then thawed to the second set temperature, so that the freezing and thawing steps are repeated multiple times to produce the expanded hydroxylated hexagonal boron nitride; wherein, the first set temperature is -50～-5℃, the second set temperature is 10-30℃.
6. The insulating impregnating varnish according to claim 1, wherein in step (3), the mixing and stirring are performed at a temperature of 60-78°C, and the reaction that occurs in the second solvent is at a temperature of 80-120°C in the presence of an inert gas, and control the mixing and stirring to be performed in an anhydrous environment; and/or, in step (3), the compound represented by formula (I) and the expanded hydroxylation The feed mass ratio of hexagonal boron nitride is 6-12:1, the feed mass ratio of the unsaturated acid and/or unsaturated acid anhydride and the expanded hydroxylated hexagonal boron nitride is 0.05-0.5:1, and the first The first solvent is cyclohexane, the second solvent is ethyl acetate, the unsaturated acid is linoleic acid and/or methacrylic acid, and the unsaturated acid anhydride is itaconic anhydride and/or maleic anhydride .
7. The insulating impregnating varnish according to claim 1, wherein in preparing the matrix resin, the mass ratio of the modified epoxy resin to the organosilicon alcohol with silanol is 1:0.15-0.35; And/or, the condensation reaction is carried out on a catalyst at 120-180°C, and the feed mass ratio of the catalyst to the modified epoxy resin is 0.005-0.015:1.
8. The insulating impregnating varnish according to claim 1, wherein the organosilicon alcohol with silanol is a compound represented by the following formula:

   

   In the formula, e, f, g, h, i, and q are independently numbers between 0 and 20, and e, h, and i are not 0 at the same time, and e, f, and g are not 0 at the same time. , G is 0, q is not 0; R ¹ , R ² , and R ^{3 are} independently methyl, vinyl or phenyl.
9. The insulating impregnating varnish according to claim 1, wherein the diluent is polypropylene glycol diglycidyl ether or neopentyl glycol diglycidyl ether or a combination of both, and the curing agent is methyl tetrahydrogen Phthalic anhydride or methylhexahydrophthalic anhydride or a combination of the two; and/or, in the insulating dipping varnish, the mass ratio of the matrix resin, the diluent and the curing agent is 1:0.05-0.25:0.35 -0.7.
10. A method for preparing insulating impregnating varnish according to any one of claims 1-9, characterized in that the preparation method comprises the following steps:

    (a) Preparation of hydrophobic hexagonal boron nitride nanosheets containing vinyl groups;

    (b) The epoxy resin, the vinyl-containing hydrophobic hexagonal boron nitride nanosheets prepared in step (a), and the remaining raw materials are polymerized in the presence of an initiator in a third solvent to form the modified ring Oxygen resin

    (c) Condensing the modified epoxy resin prepared in step (b) with the organosilicon alcohol having silanol groups to form the matrix resin;

    (d) Mixing the matrix resin produced in step (c) with a diluent and a curing agent to prepare the insulating impregnating varnish.

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