KR20230132049A - Plasma treated boron nitride nanosheets-reinforced epoxy composites and its manufacturing method - Google Patents

Abstract

Plasma-treated boron nitride nanosheets and epoxy resin are ultrasonicated and mixed in an organic solvent to obtain a stable dispersion. After removing the organic solvent, the mixture is mixed with a curing agent and poured manually into a mold in a hot press for 2 to 12 hours in a total of 3 steps. The purpose is to provide an epoxy composite material reinforced with plasma-treated boron nitride nanosheets that have improved mechanical strength and thermal properties by hardening.
More specifically, (1) surface treatment of boron nitride nanosheets using a plasma processor; (2) mixing the boron nitride nanosheets plasma-treated in step (1) with an epoxy resin using at least one organic solvent selected from acetone, ethanol, methanol, and ether; (3) stabilizing the mixture prepared in step (2); (4) adding at least one type of curing agent among amine-based, acid anhydride-based, polyamide-based, anionic polymerization-type, and multi-tube type curing agents to the mixture prepared in step (3); (5) stabilizing the mixture prepared in step (4) in a vacuum oven; and (6) pouring the mixture of boron nitride nanosheets, epoxy resin, and curing agent prepared in step (5) into a mold and curing it. It provides a method for manufacturing an epoxy composite material containing.

Description

Plasma-treated boron nitride nanosheet-reinforced epoxy composite material and its manufacturing method {PLASMA TREATED BORON NITRIDE NANOSHEETS-REINFORCED EPOXY COMPOSITES AND ITS MANUFACTURING METHOD}

The present invention relates to plasma treated boron nitride nanosheets (PBNNS) epoxy composite materials and a method for manufacturing the same. More specifically, to PBNNS, which has improved thermal conductivity, interface, and mechanical properties of epoxy composite materials. It relates to reinforced epoxy composite materials and their manufacturing methods.

Epoxy, which has two or more epoxy groups (C-O-C) in the molecule, can be manufactured into a hard and insoluble polymer material by reacting with various hardeners. Due to its properties such as high tensile modulus, adhesive properties, chemical resistance, and structural stability, epoxy resin is used as a base material for composites in aerospace, ships, automobiles, coating materials, and electrical and electronic industries. However, the high crosslinking reaction of the cured epoxy resin increases the brittleness of the epoxy composite material, making it very vulnerable to impact, and the low thermal conductivity (0.2 W/mK) is causing problems with thermal stability.

Meanwhile, recent studies have been reported introducing methods such as combining other polymers, carbon materials, and nano- or micro-sized particles to improve mechanical strength and thermal conductivity.

Among various filler materials, ceramic materials can be combined with an epoxy base to improve mechanical properties and thermal conductivity. Among various ceramic materials, boron nitride nanosheets have unique surface characteristics of a two-dimensional structure, excellent thermal conductivity and stability, and excellent mechanical and friction characteristics. However, boron nitride nanosheets require surface modification due to the agglomeration phenomenon due to van der Waals interaction. Recently, research cases have been reported in which the surface of these boron nitride nanosheets was modified and introduced into a polymer matrix to improve the mechanical properties and thermal conductivity of existing polymers.

The purpose of the present invention is to provide an epoxy material with enhanced mechanical strength and thermal conductivity, a boron nitride nanosheet-reinforced epoxy composite material surface-treated with plasma, and a method for manufacturing the same.

In order to achieve the above object, the present invention provides an epoxy composite material with improved mechanical strength and thermal conductivity and a method for manufacturing the same.

The method for producing a plasma-treated boron nitride nanosheet-reinforced epoxy composite material of the present invention includes the steps of (1) surface treating the boron nitride nanosheet using a plasma processor; (2) mixing the boron nitride nanosheets plasma-treated in step (1) with an epoxy resin using at least one organic solvent selected from acetone, ethanol, methanol, and ether; (3) stabilizing the mixture prepared in step (2); (4) adding at least one type of curing agent among amine-based, acid anhydride-based, polyamide-based, anionic polymerization-type, and multi-tube type curing agents to the mixture prepared in step (3); (5) stabilizing the mixture prepared in step (4) in a vacuum oven; and (6) pouring the mixture of boron nitride nanosheets, epoxy resin, and curing agent prepared in step (5) into a mold and curing it. Includes.

According to the present invention as described above, by using plasma-treated boron nitride nanosheets as a filler and adding them to the epoxy resin, many functional groups of the functional boron nitride nanosheets form a strong bond with the epoxy resin, which is easily processed into a thermosetting resin. By deriving interfacial bonding force, an epoxy composite material with improved mechanical strength and thermal conductivity is produced.

Figure 1 is a graph comparing the thermal conductivity and degree of improvement of an epoxy composite material reinforced with PBNNS according to an embodiment of the present invention and a comparative example.
Figure 2 is a graph comparing the fracture toughness and degree of improvement of an epoxy composite material reinforced with PBNNS according to an embodiment of the present invention and a comparative example.
Figure 3 is an SEM photograph of the fracture surface after measuring the fracture toughness of Example 2 of the epoxy composite material reinforced with PBNNS manufactured in the present invention.

Hereinafter, the present invention will be described in detail.

The method for manufacturing an epoxy composite material reinforced with PBNNS of the present invention includes the steps of (1) attaching an oxygen-containing functional group to a boron nitride nanosheet using a plasma surface treatment machine; (2) After plasma treatment, mixing the plasma surface-treated boron nitride nanosheets and epoxy resin using an organic solvent; (3) stabilizing the prepared mixture; (4) adding and mixing a curing agent; (5) stabilizing the prepared mixture in a vacuum oven; (6) The prepared mixture is cured with a hot press to prepare an epoxy composite material into which hydroxyl-functional boron nitride nanosheets are introduced.

Looking at the manufacturing process of the present invention in detail, (1) nitriding using a plasma surface treatment machine (ATMOS-Multi, PLASMART co., Korea) at 14MHz and 200W for 7 minutes under argon (99%) and oxygen (1%) gas conditions. Boron nanosheets were modified. (2) Boron nitride nanosheets that had completed surface modification were mixed with epoxy resin using an organic solvent. After adding 30 g of PBNNS compared to epoxy to 200 mL of acetone (C ₃ H ₆ O), ultrasonic treatment is performed for 1 to 2 hours at a temperature range of 10 to 50 ° C. After adding the epoxy resin to the reaction mixture, it is heated and maintained at a temperature range of 30 to 65°C and stirred for 1 to 4 hours.

The step of stabilizing the mixture prepared in step (3) above was performed using the prepared mixture. It is preferable to remove the organic solvent from the mixture prepared in step (2) at a temperature ranging from 100°C to 150°C for 4 to 10 hours. Next, (4) 21 to 23 wt.% of 4,4'-diaminodiphenylmethane as a curing agent relative to 100 wt.% of epoxy resin is added to the stabilized mixture and reacted for 1 to 5 hours at a temperature range of 20 to 70°C. Next, (5) the step of stabilizing the mixture of the remaining PBNNS and epoxy resin by adding the curing agent of step (4) above was performed. In the step of stabilizing the mixture prepared in step (4) of step (5) in a vacuum oven, the mixture prepared in step (4) is formed by adding a curing agent to the epoxy resin, causing bubbles to form due to a chemical reaction, and the mixture is depressurized in a vacuum oven. It is desirable to remove air bubbles for 1 to 3 hours at a temperature range of 10 to 60°C. The bubbles generated during the mixing process form pores in the final epoxy composite material to produce a boron nitride nanosheet-reinforced epoxy composite material. The mixture prepared in step (5) is poured into the mold. Then, in the hot press, step 1 is from 60 to 90℃ for 1 to 2 hours, step 2 is from 90 to 125℃ for 1 to 2 hours, and step 3 is from 140 to 170℃ for 1 to 2 hours. An epoxy composite material reinforced with PBNNS was manufactured by curing in three steps for 3 to 6 hours. If the curing temperature is less than 110℃, it is not completely cured, and if it is higher than 170℃, it causes a decrease in physical properties.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for illustrating the present invention, and it will be obvious to those skilled in the art that the scope of the present invention should not be construed as limited by these examples.

Example 1.

Boron nitride nanosheets were modified using a plasma surface treatment machine (ATMOS-Multi, PLASMART co., Korea) at 14 MHz and 200 W for 1 minute under argon (99%) and oxygen (1%) gas conditions. Boron nitride nanosheets that had completed surface modification were mixed with epoxy resin using an organic solvent. Specifically, 30 g of PBNNS is added to 200 mL of acetone (C ₃ H ₆ O), and then ultrasonicated for 1 to 2 hours at a temperature range of 10 to 50°C. 100 g of epoxy resin was added to the reaction mixture, heated and maintained at a temperature range of 30 to 65°C, and stirred for 1 to 4 hours. Then, the organic solvent is removed for 4 to 10 hours at a temperature ranging from 100°C to 150°C. Thereafter, 21 to 23 wt.% of 4,4'-diaminodiphenylmethane as a curing agent relative to 100 wt.% of the epoxy resin is added and reacted for 1 to 5 hours at a temperature range of 20 to 70°C. Afterwards, air bubbles were removed in a vacuum oven under reduced pressure at a temperature ranging from 10 to 60°C for 1 to 3 hours. After pouring into the mold, the first step is 1 to 2 hours at a temperature range of 60 to 90℃, the second step is 1 to 2 hours at a temperature range of 90 to 125℃, and the third step is 1 to 2 hours at a temperature range of 140 to 170℃ in a hot press. An epoxy composite material reinforced with PBNNS was manufactured by curing in three steps, from 2 to 8 hours, for a total of 2 hours.

Example 2.

The same process as Example 1 was performed, but the plasma surface treatment time of PBNNS was set to 3 minutes to produce an epoxy composite material reinforced with PBNNS.

Example 3.

An epoxy composite material reinforced with PBNNS was manufactured in the same manner as in Example 1, except that the PBNNS plasma surface treatment time was 5 minutes.

Example 4.

An epoxy composite material reinforced with PBNNS was manufactured in the same manner as in Example 1, except that the PBNNS plasma surface treatment time was 7 minutes.

Example 5.

An epoxy composite material reinforced with PBNNS was manufactured in the same manner as in Example 1, except that the PBNNS plasma surface treatment time was 10 minutes.

Example 6.

The same process as Example 1 was performed, but the plasma surface treatment time of PBNNS was set to 60 minutes to produce an epoxy composite material reinforced with PBNNS.

Example 7.

The same process as Example 1 was performed, but the PNMMS plasma surface treatment time was set to 120 minutes to produce an epoxy composite material reinforced with PBNNS.

Comparative Example 1.

BNNS was mixed with epoxy resin using an organic solvent. After adding 30 g of BNNS compared to epoxy to 200 mL of acetone (C ₃ H ₆ O), ultrasonic treatment is performed for 1 to 2 hours at a temperature range of 10 to 50 ° C. After adding the epoxy resin to the reaction mixture, it is heated and maintained at a temperature range of 30 to 65°C and stirred for 1 to 4 hours. Then, the organic solvent is removed for 4 to 10 hours at a temperature ranging from 100°C to 150°C. Thereafter, 21 to 23 wt.% of 4,4'-diaminodiphenylmethane as a curing agent relative to 100 wt.% of the epoxy resin is added and reacted for 1 to 5 hours at a temperature range of 20 to 70°C. Afterwards, air bubbles were removed in a vacuum oven under reduced pressure at a temperature ranging from 10 to 60°C for 1 to 3 hours. After pouring into the mold, the first step is 1 to 2 hours at a temperature range of 60 to 90℃, the second step is 1 to 2 hours at a temperature range of 90 to 125℃, and the third step is 1 to 2 hours at a temperature range of 140 to 170℃ in a hot press. An epoxy composite material reinforced with BNNS was manufactured by curing in three steps, from 3 to 6 hours, for a total of 2 hours.

Measurement Example 1. Thermal conductivity test of epoxy composite material reinforced with PBNNS manufactured in the present invention

Thermal conductivity was measured at least three times after graphite spray coating using a thermal conductivity analyzer (LFA 447 NanoFlash® Nederland, Germany). Additionally, an infrared thermal imaging camera was used to examine the heat absorption ability of the prepared PBNNS-reinforced basalt fiber-reinforced epoxy composite.

Measurement Example 2. Fracture toughness test of epoxy composite material reinforced with PBNNS manufactured in the present invention

The fracture toughness test was performed using a universal testing machine (Lloyd LR5k) using a short-beam three-point bending test method after manufacturing specimens of epoxy composite materials reinforced with PBNNS according to ASTM E399.

Measurement Example 3. Observation of fracture surface after fracture toughness of epoxy composite material reinforced with PBNNS manufactured in the present invention

In the present invention, scanning electron microscopy (SEM, SU 8010, Hitachi, Ltd., Japan) was used to observe whether the structure of the epoxy composite reinforced with PBNNS was changed.

Next, the manufacturing conditions of the epoxy composite material reinforced with PBNNS according to the present invention are shown in Table 1, and the thermal conductivity, surface energy, fracture toughness, and The degree of improvement and numerical values are shown in Table 2.

As above, specific parts of the present invention have been described in detail, and it is clear to those skilled in the art that these specific techniques are merely preferred embodiments and do not limit the scope of the present invention. something to do. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (6)

(1) surface treatment of boron nitride nanosheets using a plasma processor;
(2) mixing the boron nitride nanosheets plasma-treated in step (1) with an epoxy resin using at least one organic solvent selected from acetone, ethanol, methanol, and ether;
(3) stabilizing the mixture prepared in step (2);
(4) adding at least one type of curing agent among amine-based, acid anhydride-based, polyamide-based, anionic polymerization-type, and multi-tube type curing agents to the mixture prepared in step (3);
(5) stabilizing the mixture prepared in step (4) in a vacuum oven; and
(6) pouring the mixture of boron nitride nanosheets, epoxy resin, and curing agent prepared in step (5) into a mold and curing it; Method for producing an epoxy composite material comprising. According to claim 1,
Step (1) is the step of plasma treating boron nitride nanosheets for 1 to 120 minutes at 10 to 80 MHz and 200 to 1000 W under the condition of one or more gases of argon, nitrogen, oxygen and hydrogen using a plasma surface treatment machine. and
In step (2), 25 to 35 wt.% of plasma-treated boron nitride nanosheets relative to 100 wt.% of epoxy resin are added to 10 to 1000 mL of organic solvent, and then ultrasonicated for 1 to 24 hours at a temperature range of 10 to 60°C. A method of producing an epoxy composite material, which includes adding an epoxy resin to the reaction mixture, heating and maintaining it at a temperature range of 20 to 120°C, and stirring for 1 to 24 hours. According to claim 1,
The step (3) is a step of stabilizing the mixture prepared in step (2) by heating it in the temperature range of 20 to 300°C for 1 to 24 hours to remove the organic solvent. According to claim 1,
The step (4) is the step of adding the curing agent to the mixture prepared in step (3) at an epoxy resin equivalent ratio of 1 to 100 g and reacting the mixture for 1 to 12 hours at a temperature range of 20 to 120°C. Manufacturing of an epoxy composite material. method. According to claim 1,
The step (5) is a step of stabilizing the mixture prepared in step (4) by removing air bubbles in a vacuum oven under reduced pressure at a temperature of 10 to 200°C for 1 to 24 hours. According to claim 1,
In step (6), the mixture prepared in step (5) is poured into a mold and cured in a hot press at a temperature range of 20 to 90°C for 1 to 6 hours, then cured at a temperature range of 90 to 140°C for 1 to 8 hours, and then A method of manufacturing an epoxy composite material, which involves curing in a temperature range of 140 to 300°C for 1 to 12 hours.