CN111019330A

CN111019330A - Preparation method of highly-filled hexagonal boron nitride/waterborne polyurethane composite material

Info

Publication number: CN111019330A
Application number: CN202010014231.3A
Authority: CN
Inventors: 裴凯; 田晓慧; 孙金煜; 元以中
Original assignee: East China University of Science and Technology
Current assignee: East China University of Science and Technology
Priority date: 2020-01-07
Filing date: 2020-01-07
Publication date: 2020-04-17

Abstract

The invention discloses a preparation method of a hexagonal boron nitride/waterborne polyurethane composite material, which comprises the following steps: the high-thermal-conductivity hexagonal boron nitride/waterborne polyurethane composite material is prepared by taking commercial-grade hexagonal boron nitride and waterborne polyurethane as raw materials, modifying the surface of the hexagonal boron nitride by a hydrothermal method, taking gamma-polyglutamic acid as a dispersing aid and curing at room temperature to form a film. Can realize high content filling of commercial grade hexagonal boron nitride in the water-based polyurethane and realize higher thermal conductivity of the composite material. By the method, 25% of commercial grade hexagonal boron nitride can be filled in the waterborne polyurethane, so that the composite material has high heat-conducting property. The method has low cost and simple and feasible process, and is suitable for large-scale production.

Description

Preparation method of highly-filled hexagonal boron nitride/waterborne polyurethane composite material

Technical Field

The invention relates to the field of inorganic-organic composite materials, in particular to a preparation method of a hexagonal boron nitride/waterborne polyurethane composite material.

Background

At present, with the rapid development of electronic information technology, electronic components are increasingly miniaturized and have higher power. Highly integrated electronic devices generate a large amount of heat during operation, and if the heat cannot be discharged in time, the temperature of the working environment rises, thereby causing thermal failure or reduced working efficiency and other consequences. Hexagonal boron nitride is a two-dimensional layered material and is called "white graphene" because it has a similar structure to graphene. In addition, hexagonal boron nitride also has excellent insulating properties, and thus can be used in the field of heat dissipation where insulation is required.

The waterborne polyurethane is a high polymer material, and has wide application in the fields of coatings, synthetic leather, adhesives and the like due to environmental protection and good comprehensive performance. However, the low thermal conductivity of the waterborne polyurethane limits its application in the field of heat dissipation. Currently, inorganic high thermal conductive fillers are generally added to a polymeric matrix to increase the thermal conductivity of the composite. The heat transfer process of the polymer-based composite material is essentially the propagation process of phonons, so that the establishment of a good heat conduction path is a key factor for improving the composite material.

The hexagonal boron nitride has high specific surface energy, large specific surface area and easy agglomeration, is difficult to be uniformly dispersed in the waterborne polyurethane, is easy to be aggregated and separated out in the film forming process, and is difficult to be filled in the waterborne polyurethane matrix at high content. The low-filling-amount hexagonal boron nitride can not effectively construct a heat conduction path, so that the heat conductivity of the composite material is not obviously improved. In many of the conventional documents, hexagonal boron nitride is exfoliated to a nanometer level and added to a polymer as a heat conductive filler. However, the stripping process not only has low yield, but also causes a great deal of energy waste. Therefore, a simple and feasible method is needed to be designed, and the hexagonal boron nitride can be filled in the aqueous polyurethane matrix in a high content.

Disclosure of Invention

Aiming at the problems, the technical problem solved by the invention is to realize high-content filling of hexagonal boron nitride in aqueous polyurethane by carrying out surface modification on commercial-grade hexagonal boron nitride and adding gamma-polyglutamic acid as an inorganic filler dispersant, so that a good heat conduction path is formed in the composite material, the heat conductivity is improved, the cost is reduced, and the energy is saved.

The invention provides a preparation method of a high-filling hexagonal boron nitride/waterborne polyurethane composite material, which is characterized in that commercial-grade hexagonal boron nitride and waterborne polyurethane are used as raw materials, the surface of the hexagonal boron nitride is modified, a dispersing auxiliary agent is added, and the hexagonal boron nitride/waterborne polyurethane composite material is solidified at room temperature to form a film; the preparation method comprises the following steps: (1) mixing hexagonal boron nitride, sodium hydroxide, potassium hydroxide and isopropanol in a beaker, and carrying out ultrasonic treatment to obtain a uniformly mixed solution. (2) And (2) putting the mixed solution obtained in the step (1) into a hydrothermal reaction kettle with a polytetrafluoroethylene lining, repeatedly washing after the hydrothermal reaction is finished, and putting the mixture into a vacuum oven for drying to obtain the surface modified hexagonal boron nitride. (3) And (3) mixing the modified hexagonal boron nitride, the gamma-polyglutamic acid and the waterborne polyurethane obtained in the step (2) in a beaker, and stirring at a high speed to uniformly mix the solution. (4) And (4) weighing a proper amount of the uniformly mixed solution obtained in the step (3), pouring the uniformly mixed solution into a polystyrene culture dish, and curing to obtain the hexagonal boron nitride/waterborne polyurethane composite material.

Preferably; in the step (2), the surface treatment is carried out on the hexagonal boron nitride, and the specific process is as follows: placing 2g of hexagonal boron nitride, 3g of sodium hydroxide, 2g of potassium hydroxide and 20ml of isopropanol into a hydrothermal reaction kettle with a polytetrafluoroethylene lining, taking out and filtering after the hydrothermal reaction is finished, and washing the precipitate to be neutral by using deionized water; the precipitate was then dried in an oven at 60 ℃ to give surface-modified hexagonal boron nitride.

Preferably, the hydrothermal reaction temperature in the step (2) is 150-.

Preferably, the gamma-polyglutamic acid in the step (3) is prepared by a microbial fermentation method, the molecular weight is 70-100 ten thousand, and the addition amount is 0.5% -2% of the mass of the waterborne polyurethane.

Preferably, the curing manner in the step (4) is to cure at room temperature for 48 hours and then cure at 60 ℃ for 8 hours.

Further, the high-filling hexagonal boron nitride/waterborne polyurethane composite material is characterized in that the mass percentage of the hexagonal boron nitride is 0-25%.

Further, the highly filled hexagonal boron nitride/waterborne polyurethane composite material is characterized in that hexagonal boron nitride is in a commercial grade and has a particle size of 4-5 microns.

The invention has the beneficial effects that:

(1) the hydrothermal treatment method increases hydrophilic groups-hydroxyl groups on the surface of the hexagonal boron nitride, and improves the water dispersibility of the boron nitride. The gamma-polyglutamic acid is added as a dispersing agent, so that the high-content filling of commercial grade hexagonal boron nitride in the aqueous polyurethane matrix is realized, and the filling amount can reach 25%. When the filling amount of the hexagonal boron nitride reaches 25%, the thermal conductivity of the hexagonal boron nitride/waterborne polyurethane reaches 1.77W/(m.K), which is 7 times of that of the pure waterborne polyurethane. (2) The high-filling hexagonal boron nitride/waterborne polyurethane composite material prepared by the invention takes commercial grade hexagonal boron nitride as a raw material, has simple preparation process and low cost, and is suitable for industrial production.

Drawings

FIG. 1 is a graph showing the thermal conductivity curves of hexagonal boron nitride/aqueous polyurethane composites of examples 1-6

Detailed Description

The invention is further illustrated with reference to specific examples, but the scope of the invention is not limited thereto.

Example 1. an aqueous polyurethane emulsion having a solid content of 2g was weighed into a beaker, 0.02g of γ -polyglutamic acid was added thereto, the solution was stirred magnetically at 300rpm for 1 hour to mix the solution uniformly, and then the mixed solution was poured into a polystyrene petri dish, and was cured at room temperature for 48 hours and then at 60 ℃ for 8 hours to obtain an aqueous polyurethane material having a hexagonal boron nitride loading of 0.

Example 2. (1) 2g of hexagonal boron nitride, 3g of sodium hydroxide, 2g of potassium hydroxide and 20ml of isopropanol were weighed and mixed in a beaker, and the solution was uniformly mixed by ultrasonic dispersion for 20 minutes, and then the mixed solution was poured into a polytetrafluoroethylene-lined hydrothermal reaction vessel and reacted at 180 ℃ for 12 hours. After the reaction was completed, the reaction mixture was repeatedly centrifuged and washed with deionized water 8 times. And collecting the centrifuged solid, and drying in a vacuum oven at 60 ℃ to obtain the modified hexagonal boron nitride. (2) Weighing 0.1g of modified hexagonal boron nitride and 0.019g of gamma-polyglutamic acid in the step (1), adding the modified hexagonal boron nitride and the gamma-polyglutamic acid into aqueous polyurethane emulsion with the solid content of 1.9g, magnetically stirring the mixture at 500rpm for 1 hour to uniformly mix the solution, then pouring the mixed solution into a polystyrene culture dish, firstly curing the mixed solution at room temperature for 48 hours, and then curing the mixed solution at 60 ℃ for 8 hours to obtain the hexagonal boron nitride/aqueous polyurethane composite material with the hexagonal boron nitride filling amount of 5%.

Examples 3 to 6. the preparation method was the same as in example 2 except that the amounts of the modified hexagonal boron nitride, gamma-polyglutamic acid and aqueous polyurethane were changed so that the hexagonal boron nitride in the hexagonal boron nitride/aqueous polyurethane composite was 10%, 15%, 20% and 25% by mass, and the components in examples 3 to 6 were as shown in table 1. The thermal conductivity of examples 1-6 are shown in figure 1.

TABLE 1 table of the compositions of examples 3-6

Claims

1. A preparation method of a highly-filled hexagonal boron nitride/waterborne polyurethane composite material is characterized by comprising the following steps: the method comprises the following steps of taking commercial grade hexagonal boron nitride and waterborne polyurethane as raw materials, modifying the surface of the hexagonal boron nitride, adding a dispersing aid, and curing at room temperature to form a film to prepare the high-filling hexagonal boron nitride/waterborne polyurethane composite material; the preparation method comprises the following steps:

(1) mixing hexagonal boron nitride, sodium hydroxide, potassium hydroxide and isopropanol in a beaker, and performing ultrasonic treatment to obtain a uniformly mixed solution;

(2) putting the mixed solution obtained in the step (1) into a hydrothermal reaction kettle with a polytetrafluoroethylene lining, repeatedly washing after the hydrothermal reaction is finished, and putting the mixture into a vacuum oven for drying to obtain surface-modified hexagonal boron nitride;

(3) mixing the modified hexagonal boron nitride, the gamma-polyglutamic acid and the aqueous polyurethane emulsion obtained in the step (2) in a beaker, and stirring at a high speed to uniformly mix the solution;

(4) and (4) weighing a proper amount of the uniformly mixed solution obtained in the step (3), pouring the uniformly mixed solution into a polystyrene culture dish, and curing to obtain the hexagonal boron nitride/waterborne polyurethane composite material.

2. The method for preparing the highly filled hexagonal boron nitride/aqueous polyurethane composite material according to claim 1, wherein the method comprises the following steps: the surface treatment is carried out on the hexagonal boron nitride, and the specific process is as follows: placing 2g of hexagonal boron nitride, 3g of sodium hydroxide, 2g of potassium hydroxide and 20ml of isopropanol into a hydrothermal reaction kettle with a polytetrafluoroethylene lining, taking out and filtering after the hydrothermal reaction is finished, and washing the precipitate to be neutral by using deionized water; and drying the precipitate in a vacuum oven at 60 ℃ to obtain the surface modified hexagonal boron nitride.

3. The method for preparing the highly filled hexagonal boron nitride/aqueous polyurethane composite material according to claim 1, wherein the method comprises the following steps: the hydrothermal reaction temperature in the step (2) is 150-200 ℃, and the hydrothermal time is 8-16 hours.

4. The method for preparing the highly filled hexagonal boron nitride/aqueous polyurethane composite material according to claim 1, wherein the method comprises the following steps: in the step (3), the gamma-polyglutamic acid is used as a dispersing agent of hexagonal boron nitride and prepared by a microbial fermentation method, the molecular weight is 70-100 ten thousand, and the addition amount is 0.5-2% of the mass of the waterborne polyurethane.

5. The method of preparing a highly filled hexagonal boron nitride/aqueous polyurethane composite material according to any one of claims 1 to 4, wherein: the curing mode in the step (4) is that the curing is carried out for 48 hours at room temperature and then for 8 hours at 60 ℃.

6. The method of preparing a highly filled hexagonal boron nitride/aqueous polyurethane composite material according to any one of claims 1 to 4, wherein: the hexagonal boron nitride/waterborne polyurethane composite material comprises 0-25% of hexagonal boron nitride by mass.

7. The method of preparing a highly filled hexagonal boron nitride/aqueous polyurethane composite material according to any one of claims 1 to 4, wherein: the hexagonal boron nitride is of commercial grade and has a particle size of 4-5 μm.