WO2017166870A1

WO2017166870A1 - Method for manufacturing high color gamut white light led lamp bead based on red light quantum dot

Info

Publication number: WO2017166870A1
Application number: PCT/CN2016/110960
Authority: WO
Inventors: 高丹鹏; 邢其彬; 苏宏波
Original assignee: 深圳市聚飞光电股份有限公司
Priority date: 2016-03-30
Filing date: 2016-12-20
Publication date: 2017-10-05
Also published as: CN105679894B; CN105679894A

Abstract

The invention belongs to the field of LED backlight processing, and specifically relates to a method for manufacturing a high color gamut white light LED lamp bead based on a red light quantum dot. The present invention uses a red light quantum dot fluorescent powder, and encapsulates the red light right quantum dot fluorescent powder within a backlight LED lamp bead utilizing an organic solvent by way of first dissolving and then extracting same, where a blue light chip is used for excitation, to obtain a high color gamut white light. By means of related technical means, the invention greatly reduces the difficulty of encapsulation work, and solves the technical problems that it is difficult to mix the quantum dot fluorescent powder with encapsulation glue, that the quantum dot fluorescent powder easily agglomerates and loses effect, and that the encapsulation glue can hardly solidify due to the influence of organic matters, having a bright market prospect and high economic value.

Description

High color gamut white LED lamp bead based on red light quantum dot

Technical field

The invention belongs to the field of LED backlight processing, and particularly relates to a method for manufacturing a high color gamut white LED lamp bead based on red light quantum dots.

Background technique

Since the beginning of the 21st century, backlight technology has developed rapidly, and new technologies and new products have been introduced. LED backlights have become the mainstream in the market. Compared with the traditional CCFL backlight, LED backlight has many advantages such as high color gamut, high brightness, long life, energy saving and environmental protection, real-time color control, etc. Especially the high color gamut LED backlight enables the application of its TV, mobile phone, Electronic products such as tablets have more vivid colors and higher color reproduction. At present, the commonly used LED backlight uses a blue chip to excite the YAG yellow phosphor. Due to the lack of red light in the backlight, the color gamut value can only reach NTSC 65% to 72%. In order to further improve the color gamut value, the technician generally adopts a method in which the blue light chip simultaneously excites the red phosphor and the green phosphor, but since the half-wave width of the phosphor is wider, even if this method is used, only Can increase the color gamut value of the backlight to about 80% NTSC. At the same time, the excitation efficiency of the existing phosphor is low, and a large amount of phosphor is required for realizing high color gamut white light, which leads to a high concentration of phosphor powder (a ratio of phosphor to package glue) in the LED packaging process, thereby greatly increasing the packaging operation. Difficulty and poor product rate.

In recent years, quantum dot materials have been paid more and more attention. In particular, quantum dot phosphors have a series of unique optical properties such as adjustable spectrum with size, narrow half-wave width of emission peak, large Stokes shift, and high excitation efficiency. Wide attention. At present, quantum dot phosphors achieve high color gamut white light mainly in the following ways: (1) The quantum dot phosphor is made into an optical film, filled in a light guide plate or attached to a liquid crystal screen, and excited by a blue or ultraviolet backlight lamp bead. (2) The quantum dot phosphor powder is made into a glass tube, placed on the side of the screen, and excited by blue or ultraviolet backlight beads to obtain high color gamut white light. These two implementations have been introduced with related products, such as the quantum dot film of TCL. TV. However, the two implementations are complicated in process, low in light conversion efficiency, and high in cost, and it is difficult to achieve large-scale industrialization. To this end, some researchers have tried to enclose quantum dot phosphors and LED lamp beads to obtain high color gamut white light, but due to the existence of quantum dot phosphors, it is difficult to mix with the package glue, and it is easy to agglomerate failure, and the impurities will be destroyed. It is difficult to make substantial progress in related research, such as encapsulation of glue, which makes the encapsulation glue difficult to cure.

Summary of the invention

Therefore, the technical problem to be solved by the present invention is to overcome the technical bottleneck of the prior art complicated process, low light conversion efficiency, high cost, and difficult to realize large-scale industrialization, thereby proposing a high color gamut value and avoiding quantum dots. A method for producing a high color gamut white LED lamp bead based on red light quantum dots which can be agglomerated by phosphors, has high yield, and can be mass-produced industrially.

In order to solve the above technical problem, the present invention discloses a method for fabricating a high color gamut white LED lamp bead based on a red light quantum dot, and the process steps are as follows:

1) weigh 1 part by weight of red light quantum dot phosphor and 50 to 2000 parts by weight of an organic solvent, and add a corresponding amount of organic solvent to the red light quantum dot phosphor to obtain a mixed solution;

2) ultrasonically treating the mixed solution obtained in the step 1) until the red light quantum dot phosphor is completely dissolved in the organic solvent to obtain a clear solution;

3) weigh 5 to 1000 parts by weight of the encapsulating glue, pour into the red light quantum dot clear solution obtained in step 2); magnetically stir the quantum dot solution mixed with the encapsulating glue;

4) The mixture obtained in the step 3) is subjected to vacuum defoaming and stirring; the organic solvent in the mixture obtained in the step 3) is extracted to obtain a uniformly mixed red light quantum dot fluorescent gel;

5) Weigh 1-50 parts by weight of the green fluorescent powder, add to the red light quantum dot fluorescent glue obtained in step 4), stir the fluorescent glue, and mix the green fluorescent powder into the red light quantum dot fluorescent glue;

6) vacuum defoaming the fluorescent glue mixed with the green phosphor in step 5), mixing the green phosphor with the red quantum dot fluorescent gel, and completely defoaming the fluorescent gel to obtain red and green fluorescent glue. ;

7) The red and green fluorescent glue obtained in the step 6) is dropped into the LED holder fixed with the blue chip, and baked to cure the fluorescent glue, thereby obtaining a high color gamut white LED lamp bead.

Preferably, in the step 1), the peak wavelength of the emitted light of the red light quantum dot phosphor is 600-660 nm; and the peak wavelength of the emitted light of the blue chip is 430-470 nm.

Preferably, in the step 1), the red light quantum dot phosphor has a particle diameter of 1 to 10 nm.

Preferably, in the step 1), the red light quantum dot phosphor is BaS, AgInS ₂ , NaCl, Fe ₂ O ₃ , In ₂ O ₃ , InAs, InN, InP, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe. At least one of GaAs, GaN, GaS, GaSe, InGaAs, MgS, MgSe, MgTe, PbS, PbSe, PbTe, Cd(S _x Se _1-x ), BaTiO ₃ , PbZrO ₃ , CsPbCl ₃ , CsPbBr ₃ , and CsPbI ₃ One.

Preferably, in the step 1), the organic solvent is at least one of n-hexane, cyclohexane, n-octane, toluene, dichlorotoluene, dichloromethane, chloroform, and pyridine.

Preferably, in the step 1), the encapsulant is one of an epoxy encapsulant, a silicone encapsulant, and a polyurethane encapsulant.

Preferably, in the step 5), the green light fluorescent powder has a peak light wavelength of 520 to 555 nm.

Preferably, in the step 5), the green phosphor is at least one of a rare earth element doped silicate, an aluminate, a phosphate, a nitride, and a fluoride phosphor.

Preferably, in the step 3), the magnetic stirring is specifically: placing the quantum dot solution mixed with the sealing glue in a magnetic stirrer, controlling the rotational speed of the magnetic rotor to be 120-350 rpm, and stirring for 5-30 min.

Preferably, the specific step of the vacuum degassing agitation in the step 4) is: placing the mixed liquid obtained in the step 3) in a vacuum defoaming machine, and vacuuming until the pressure in the defoaming machine is 0 to 0.2 Kpa, and controlling off The stirring speed of the bubble machine is 300-1200 rpm/min, the defoaming temperature is 40-55 ° C, and the mixture is vacuum defoamed and stirred for 15 to 90 min; the baking temperature in the step 7) is 120-180 ° C, baking The time is 0.5-6h.

The above technical solution of the present invention has the following advantages over the prior art:

(1) The high color gamut white LED lamp bead obtained by the red light quantum dot of the invention greatly improves the color gamut value of the backlight bead, and is up to 92% of NTSC.

(2) The high color gamut white LED lamp bead obtained by using the red light quantum dot of the present invention, due to quantum dot fluorescence The light powder has high excitation efficiency, and the phosphor concentration is low during the packaging operation, which reduces the difficulty of packaging operation and product defect rate, and is suitable for mass industrial production.

(3) The high color gamut white LED lamp bead obtained by the red light quantum dot adopts the organic solvent as a connecting bridge to uniformly mix the quantum dot and the package glue, and avoids the agglomeration failure phenomenon of the quantum dot phosphor powder, which is remarkable Improve the quality of high color gamut white LED lamp beads.

(4) The high color gamut white LED lamp bead obtained by using the red light quantum dot of the invention removes the organic solvent from the sealing glue by vacuum defoaming, thereby avoiding poisoning and hardening of the encapsulating glue by the influence of the organic solvent. Thereby solving the technical bottleneck of the quantum dot phosphor packaging, and greatly improving the reliability of the high color gamut white LED lamp bead.

DRAWINGS

In order to make the content of the present invention easier to understand, the present invention will be further described in detail below with reference to the accompanying drawings

1 is a schematic view showing a manufacturing process of a high color gamut white LED lamp bead according to Embodiment 1-3;

2 is a structural diagram of the high color gamut white LED lamp bead described in Embodiment 1;

3 is an emission spectrum of the high color gamut white LED lamp bead described in Embodiment 1;

Reference numerals in the figures are indicated as: 1-stent; 2-blue chip; 3-bond wire; 4-red quantum dot phosphor; 5-green rare earth phosphor; 6-package glue.

detailed description

Embodiment 1 This embodiment discloses a method for fabricating a high color gamut white LED lamp bead based on a red light quantum dot. The specific process steps are as shown in FIG. 1 :

1) Weigh a certain amount of MgTe red light quantum dot phosphor with a peak wavelength of 630 nm (red light quantum dot phosphor is commercially available and its particle size is 5 nm). According to the mass ratio of the red light quantum dot to the organic solvent is 1:1000, an appropriate amount of the organic solvent C ₇ H ₈ (toluene) is added to the red light quantum dot phosphor.

2) The mixed solution obtained in the step 1) is placed in an ultrasonic cleaner for ultrasonic treatment. The ultrasonic bath temperature of the ultrasonic cleaning machine was controlled at 35 ° C, the ultrasonic frequency was 70 KHz, and the ultrasonic treatment time was 40 min, so that the red light quantum dot phosphor was completely dissolved in the organic solvent to obtain a clear solution.

3) According to the package glue A: package glue B mass ratio of 1:10 (package A, package B is silicone package), red light quantum dot and package glue (including package glue A and package glue B) quality A ratio of 1:500, weigh a certain amount of encapsulating glue A and encapsulating glue B, and pour into the red light quantum dot clear solution obtained in step 2). The quantum dot solution mixed with the encapsulating glue was placed in a magnetic stirrer to control the rotation speed of the magnetic rotor to 250 rpm, and stirred for 20 min to uniformly mix the red light quantum dot solution with the encapsulating glue A and the sealing glue B.

4) The mixture obtained in the step 3) is placed in a vacuum defoaming machine, vacuum is applied until the pressure in the deaerator is 0.1 Kpa, the stirring speed of the defoaming machine is controlled at 800 rpm/min, and the defoaming temperature is 48 ° C. The organic solvent in the mixture obtained in the step 3) can be extracted by vacuum defoaming and stirring for 50 minutes to obtain a uniformly mixed red light quantum dot fluorescent glue.

5) Weigh a certain amount of green fluorescent powder with a peak wavelength of 540 nm (green phosphor can be rare earth doped silicate, aluminate, phosphate, nitride, fluoride, etc.) At least one kind, the mass ratio of the green phosphor to the red quantum dot phosphor is 25:1), added to the red quantum dot fluorescent glue obtained in the step 4), and the fluorescent glue is manually stirred by the glass rod in the same direction Stir for 8 min at a constant speed to mix the green phosphor into the red quantum dot fluorescent gel.

6) The fluorescent glue mixed with the green phosphor in step 5) is placed in a vacuum defoaming machine to control the defoaming temperature to 40 ° C, the pressure of the pressure deaerator is 1 Kpa, and the defoaming stirring speed is 1500 rpm / Min, vacuum defoaming and stirring for 8 min, the green fluorescent powder and the red light quantum dot fluorescent glue are thoroughly mixed, and the fluorescent rubber is completely defoamed to obtain red and green fluorescent glue.

7) The obtained red and green fluorescent glue is dropped into a blue chip (the peak wavelength of the chip emission light is 450 nm), and the bonding wire is connected (the bonding wire material may be gold, silver, copper and other conductive alloy) In the LED holder cup case, the LED holder is placed in an oven and baked at 160 ° C for 4 hours. After the red and green fluorescent glue in the cup is cured, a high color gamut white LED lamp bead is obtained.

The obtained LED lamp bead is composed of 1 bracket, 2 blue chip, 3 bonding wire, 4 red light quantum dot phosphor, 5 green light rare earth phosphor and 6 package glue (see FIG. 2 for details).

Embodiment 2 This embodiment discloses a method for fabricating a high color gamut white LED lamp bead based on a red light quantum dot. The specific process steps are as shown in FIG. 1 :

1) Weigh a certain amount of GaAs, GaN red light quantum dot phosphor with a peak wavelength of 600 nm (red light quantum dot phosphor is commercially available and its particle size is 10 nm). According to the mass ratio of the red light quantum dot to the organic solvent is 1:50, an appropriate amount of the organic solvent CHCl ₃ (trichloromethane) is added to the red light quantum dot phosphor.

2) The mixed solution obtained in the step 1) is placed in an ultrasonic cleaner for ultrasonic treatment. The ultrasonic bath temperature of the ultrasonic cleaning machine is controlled to 45 ° C, the ultrasonic frequency is 15 KHz, and the ultrasonic treatment time is 90 min, so that the red light quantum dot phosphor is completely dissolved in the organic solvent to obtain a clear solution.

3) According to the package glue A: the package glue B mass ratio is 1:20 (package glue A, package glue B is polyurethane package glue), the mass ratio of red light quantum dot and package glue (including package glue A and package glue B) is 1:5, weigh a certain amount of package glue A and package glue B, and pour into the red light quantum dot clear solution obtained in step 2). The quantum dot solution mixed with the sealing glue was placed in a magnetic stirrer, and the magnetic rotor speed was controlled to be 350 rpm, and the mixture was stirred for 5 minutes to uniformly mix the red light quantum dot solution with the sealing glue A and the sealing glue B.

4) The mixture obtained in the step 3) is placed in a vacuum defoaming machine, and the vacuum is evacuated to a pressure of 0.1 Kpa in the defoaming machine, the stirring speed of the defoaming machine is controlled to be 1200 rpm/min, and the defoaming temperature is 40 to 55 ° C. The mixed solution was subjected to vacuum defoaming and stirring for 15 minutes, and the organic solvent in the mixed liquid obtained in the step 3) was extracted to obtain a uniformly mixed red light quantum dot fluorescent gel.

5) Weigh a certain amount of green fluorescent powder with a peak wavelength of 555 nm (green phosphor can be rare earth doped silicate, aluminate, phosphate, nitride, fluoride, etc.) At least one of the above, the mass ratio of the green phosphor to the red quantum dot phosphor is 1:1,), added to the red quantum dot fluorescent gel obtained in the step 4), and artificially stirred by a glass to the fluorescent glue. Stir in the same direction for 5 min at a constant speed to mix the green phosphor into the red quantum dot fluorescent gel.

6) The fluorescent glue mixed with the green fluorescent powder obtained in the step 5) is placed in a vacuum defoaming machine to control the defoaming temperature to be 55 ° C, the defoaming machine pressure is 0.1 Kpa, and the defoaming agent stirring speed is 2000 rpm / Min, vacuum defoaming and stirring for 3 min, the green phosphor and the red light quantum dot fluorescent glue are thoroughly mixed, and the fluorescent rubber is completely defoamed to obtain red and green fluorescent glue.

7) Drop the obtained red and green fluorescent glue into the blue chip that has been fixed (chip emission peak wave) The length is 430nm), and the LED bracket is connected to the bonding wire (the bonding wire material can be gold, silver, copper and other conductive alloy). The LED bracket is placed in an oven and baked at 120 ° C for 6 hours. After the red and green fluorescent glue in the cup is cured, the high color gamut white LED lamp bead is obtained.

The obtained LED lamp bead is composed of a bracket, a blue chip, a bonding wire, a red light quantum dot phosphor, a green rare earth phosphor, and a package glue.

Embodiment 3 This embodiment discloses a method for fabricating a high color gamut white LED lamp bead based on a red light quantum dot. The specific process steps are as shown in FIG. 1 :

1) Weigh a certain amount of AgInS red light quantum dot phosphor with a peak wavelength of 660 nm (red light quantum dot phosphor is commercially available and its particle size is 1 nm). According to the mass ratio of the red light quantum dot to the organic solvent: 1:2000, an appropriate amount of the organic solvent C ₆ H ₁ ₂ (cyclohexane) was added to the red light quantum dot phosphor.

2) The mixed solution obtained in the step 1) is placed in an ultrasonic cleaner for ultrasonic treatment. The ultrasonic bath temperature of the ultrasonic cleaning machine is controlled to 25 ° C, the ultrasonic frequency is 120 KHz, and the ultrasonic treatment time is 10 min, so that the red light quantum dot phosphor is completely dissolved in the organic solvent to obtain a clear solution.

3) According to the package glue A: the package glue B mass ratio is 1:20 (package A, package B is silicone package), red light quantum dot and package glue (including package glue A and package glue B) quality A ratio of 1:5, weigh a certain amount of encapsulating glue A and encapsulating glue B, and pour into the red light quantum dot clear solution obtained in step 2). The quantum dot solution mixed with the sealing glue was placed in a magnetic stirrer, and the magnetic rotor speed was controlled to be 350 rpm, and the mixture was stirred for 5 minutes to uniformly mix the red light quantum dot solution with the sealing glue A and the sealing glue B.

4) The mixture obtained in the step 3) is placed in a vacuum defoaming machine, vacuumed to a pressure of 0.2 Kpa in the defoaming machine, the stirring speed of the defoaming machine is controlled at 300 rpm/min, and the defoaming temperature is 55 ° C. The organic solvent in the mixture obtained in the step 3) can be extracted by vacuum defoaming and stirring for 15 minutes to obtain a uniformly mixed red light quantum dot fluorescent gel.

5) Weigh a certain amount of green fluorescent powder with a peak wavelength of 555 nm (green phosphor can be rare earth doped silicate, aluminate, phosphate, nitride, fluoride, etc.) At least one of the mass ratio of the green phosphor to the red quantum dot phosphor is 50: 1), added to the red light quantum dot fluorescent glue obtained in the step 4), artificially stirred the fluorescent glue with glass, and uniformly stirred in the same direction for 5 min, so that the green fluorescent powder is mixed into the red light quantum dot fluorescent glue.

6) The fluorescent glue mixed with the green fluorescent powder obtained in the step 5) is placed in a vacuum defoaming machine to control the defoaming temperature to 25 ° C, the defoaming machine pressure is 1.5 Kpa, and the defoaming agent stirring speed is 1100 rpm / Min, vacuum defoaming and stirring for 10 min, the green fluorescent powder and the red light quantum dot fluorescent glue are thoroughly mixed, and the fluorescent rubber is completely defoamed to obtain red and green fluorescent glue.

7) The obtained red and green fluorescent glue is dropped into the blue chip (the peak wavelength of the chip emission light is 470 nm), and the bonding wire (the bonding wire material can be gold, silver, copper and other conductive alloy) is connected. Inside the LED holder cup case, the LED holder is placed in an oven and baked at 180 ° C for 0.5 h. After the red and green fluorescent glue in the cup is cured, a high color gamut white LED lamp bead is obtained.

Experimental example

The color coordinates and color gamut values of the LED lamp beads obtained by the encapsulation method of the high color gamut white light quantum dot LED described in Examples 1-3 were tested. The results are shown in Table 1.

Table 1

	实例1Example 1	实例2Example 2	实例3Example 3
色坐标Color coordinates	(0.30,0.28)(0.30, 0.28)	(0.28,0.26)(0.28, 0.26)	(0.29,0.27)(0.29, 0.27)
NTSC色域值NTSC gamut value	93.2％93.2%	94.2％94.2%	92.5％92.5%

The above results show that the LED lamp beads obtained by the high color gamut white light quantum dot LED packaging method described in Examples 1-3 have white color and high color gamut values, all of which are above 92%.

The high color gamut white LED lamp bead obtained by the method described in the embodiment 1 is subjected to luminescence test, and the obtained emission spectrum is shown in FIG. 3. It can be seen from the figure that the lamp bead obtained by the method of the embodiment is emitted under the excitation of the blue chip. Red and green light are combined with blue light chips to form high color gamut white light. The half-wave width of the red light emission peak of the lamp bead (about 640 nm) is narrower, indicating that the emitted red light color has higher purity and the color gamut value of the lamp bead is high.

It is apparent that the above-described embodiments are merely illustrative of the examples, and are not intended to limit the embodiments. Other variations or modifications of the various forms may be made by those skilled in the art in light of the above description. There is no need and no way to exhaust all of the implementations. Obvious changes or variations resulting therefrom are still within the scope of the invention.

Claims

A method for fabricating a high color gamut white LED lamp bead based on a red light quantum dot, characterized in that the process steps are as follows:

1) weigh 1 part by weight of red light quantum dot phosphor and 50 to 2000 parts by weight of an organic solvent, and add a corresponding amount of organic solvent to the red light quantum dot phosphor to obtain a mixed solution;

2) ultrasonically treating the mixed solution obtained in the step 1) until the red light quantum dot phosphor is completely dissolved in the organic solvent to obtain a clear solution;

3) weigh 5 to 1000 parts by weight of the encapsulating glue, pour into the red light quantum dot clear solution obtained in step 2); magnetically stir the quantum dot solution mixed with the encapsulating glue;

4) The mixture obtained in the step 3) is subjected to vacuum defoaming and stirring; the organic solvent in the mixture obtained in the step 3) is extracted to obtain a uniformly mixed red light quantum dot fluorescent gel;

5) Weigh 1-50 parts by weight of the green fluorescent powder, add to the red light quantum dot fluorescent glue obtained in step 4), stir the fluorescent glue, and mix the green fluorescent powder into the red light quantum dot fluorescent glue;

6) vacuum defoaming the fluorescent glue mixed with the green phosphor in step 5), mixing the green phosphor with the red quantum dot fluorescent gel, and completely defoaming the fluorescent gel to obtain red and green fluorescent glue. ;

7) The red and green fluorescent glue obtained in the step 6) is dropped into the LED holder fixed with the blue chip, and baked to cure the fluorescent glue, thereby obtaining a high color gamut white LED lamp bead.
The method according to claim 1, wherein in the step 1), the peak wavelength of the emitted light of the red light quantum dot phosphor is 600-660 nm; and the peak wavelength of the emitted light of the blue chip is 430~ 470nm.
The method according to claim 2, wherein in the step 1), the red light quantum dot phosphor has a particle diameter of 1 to 10 nm.
The method according to claim 3, wherein in the step 1), the red light quantum dot phosphor is BaS, AgInS 2 , NaCl, Fe 2 O 3 , In 2 O 3 , InAs, InN, InP, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, GaAs, GaN, GaS, GaSe, InGaAs, MgS, MgSe, MgTe, PbS, PbSe, PbTe, Cd(S x Se 1-x ), BaTiO 3 , PbZrO 3 , At least one of CsPb Cl 3 , CsPbBr 3 , and CsPbI 3 .
The method according to claim 4, wherein in the step 1), the organic solvent is n-hexane, cyclohexane, n-octane, toluene, dichlorotoluene, dichloromethane, and chloroform. And at least one of pyridine.
The manufacturing method according to claim 5, wherein in the step 4), the encapsulant is one of an epoxy encapsulant, a silicone encapsulant, and a polyurethane encapsulant.
The method according to claim 6, wherein in the step 5), the green light phosphor has a peak wavelength of 520 to 555 nm.
The method according to claim 7, wherein in the step 5), the green phosphor is a rare earth doped silicate, aluminate, phosphate, nitride, fluoride fluorescent At least one of the powders.
The manufacturing method according to claim 8, wherein in the step 3), the magnetic stirring is specifically: placing the quantum dot solution mixed with the sealing glue in a magnetic stirrer to control the rotation speed of the magnetic rotor 120 to 350 rpm, stirring for 5 to 30 minutes.
The method according to claim 9, wherein the step of vacuum degassing agitation in the step 4) is: placing the mixture obtained in the step 3) in a vacuum defoaming machine, and evacuating to defoaming. The pressure inside the machine is 0～0.2Kpa, the stirring speed of the control defoaming machine is 300～1200rpm/min, the defoaming temperature is 40～55°C, and the mixture is vacuum defoamed and stirred for 15～90min; the step 7) is baked. The baking temperature is 120-180 ° C, and the baking time is 0.5-6 h.