A bubble-free composite forming process for tempered laminated glass

Abstract

This invention belongs to the field of tempered laminated glass technology, specifically relating to a bubble-free composite molding process for tempered laminated glass. A functional coating is also provided, which is prepared from the following components: modified silicone-acrylic emulsion, modified nano-cesium tungsten bronze, curing agent, dispersant, leveling agent, defoamer, silane coupling agent, ultraviolet absorber, film-forming aid, and deionized water. This invention utilizes the crosslinking modification of vinyltriisopropoxysilane and the grafting modification of vinylphosphonic acid to effectively improve the interfacial bonding force between the emulsion film and the glass substrate and functional fillers. Simultaneously, a modifier prepared by aminotrimethylenephosphonic acid and lanthanum chloride hexahydrate is used to modify the surface of nano-cesium tungsten bronze, solving the technical problem of easy agglomeration of unmodified nano-cesium tungsten bronze, thus laying the foundation for the high performance of functional coatings and tempered laminated glass.

Description

Technical Field

[0001] This invention belongs to the field of tempered laminated glass technology, specifically relating to a bubble-free composite molding process for tempered laminated glass. Background Technology

[0002] Tempered laminated glass, combining the high strength of tempered glass with the impact and splash resistance of laminated glass, has become an important safety glass material in construction and transportation. Its composite molding process and functional modification are key areas of research and development in the industry. Currently, tempered laminated glass is produced by laminating tempered glass with a PVB interlayer, followed by air removal through roller pressing and hot pressing in a vacuum autoclave. Applying functional coatings to the surface of the tempered glass can improve its thermal insulation and weather resistance. Functional coatings often use silicone-acrylic emulsions as the film-forming base, combined with functional fillers such as nano-cesium tungsten bronze. Dispersants, leveling agents, and curing agents are also added to regulate the coating's properties. Nano-cesium tungsten bronze, due to its excellent near-infrared blocking properties, has become one of the mainstream fillers for preparing thermally insulating functional coatings.

[0003] However, conventional silicone-acrylic emulsions have insufficient interfacial bonding with glass substrates and functional fillers. Unmodified nano-cesium tungsten bronze is prone to agglomeration, resulting in poor dispersibility. The compatibility of the coating components also needs to be improved. As a result, the functional coating formed by coating has problems such as low adhesion, poor wear resistance, water resistance and weather resistance, and poor radiation resistance. In addition, the coating has poor radiation resistance, and the visible light transmittance changes greatly after long-term use, and the heat insulation and other functions are easily degraded.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a bubble-free composite molding process for tempered laminated glass to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A functional coating, by mass percentage, is prepared from the following components: 35-60% modified silicone-acrylic emulsion, 8-18% modified nano-cesium tungsten bronze, 3-8% curing agent, 0.4-1.2% dispersant, 0.3-0.8% leveling agent, 0.2-0.6% defoamer, 0.3-0.9% silane coupling agent, 0.3-1.0% ultraviolet absorber, 0.5-2% film-forming aid, and deionized water to 100%. The modified silicone-acrylic emulsion, by weight, is prepared from the following components: 100 parts silicone-acrylic emulsion, 4-9 parts vinyltriisopropoxysilane, 2-7 parts vinylphosphonic acid, 0.15-0.35 parts azobisisobutyramidine hydrochloride initiator, and 10-20 parts deionized water.

[0007] Furthermore, the method for preparing the modified silicone-acrylic emulsion is as follows: S1. Silicone-acrylic emulsion and deionized water were added to a reactor. Nitrogen gas was introduced for 30 minutes to remove oxygen while stirring at 200 rpm. The temperature was then raised to 75°C and held for 15 minutes. Vinyltriisopropoxysilane was mixed with 70% of the initiator azobisisobutyramidine hydrochloride and added dropwise to the reactor at a rate of 0.05-0.10 parts / min. During the dropwise addition, the temperature was maintained at 75±2°C and the stirring speed was 300 rpm. After the dropwise addition was completed, the mixture was stirred at 75°C and 300 rpm for 2.5 hours to obtain a crosslinked modified emulsion intermediate. S2. Add the remaining 30% of the initiator azobisisobutyramidine hydrochloride to the crosslinking modified intermediate, and stir at 75°C and 200 r / min for 10 min; mix vinylphosphonic acid with an equal mass of deionized water and add it dropwise to the reactor at a rate of 0.15-0.20 parts / min, maintaining the temperature at 75±2°C and the stirring speed at 300 r / min during the dropwise addition; after the dropwise addition is complete, stir the reaction at 75°C and 300 r / min for 2 h, cool naturally to room temperature, and pass through a 200-mesh sieve to obtain the modified silicone-acrylic emulsion.

[0008] Furthermore, the preparation method of the modified nano-cesium tungsten bronze is as follows: S1. Weigh aminotrimethylenephosphonic acid and lanthanum chloride hexahydrate at a mass ratio of 1:0.85, and prepare 10% aqueous solutions with water. Slowly add the lanthanum chloride aqueous solution to the aminotrimethylenephosphonic acid aqueous solution at a rate of 1 mL / min, stir at 300-400 r / min, and adjust the pH to 5.5-6.0 with 10% sodium hydroxide solution. Then heat to 60℃, maintain the temperature and stir at 400-500 r / min for 3 hours, cool naturally to room temperature, let stand for 30-60 minutes to precipitate, wash the precipitate with deionized water until the pH of the washing solution is 6.5-7.0; then vacuum dry the precipitate at 60-70℃ and -0.09 MPa for 12-16 hours to obtain the modifier. S2. Weigh 20-50 nm nano-sized cesium tungsten bronze and modifier at a mass ratio of 100:5-10; dissolve the modifier in a 1:1 mixture of deionized water and anhydrous ethanol to prepare a 5% mass fraction modified solution; add nano-sized cesium tungsten bronze; and ultrasonically disperse at 150-200 W and 25-35 °C for 30 min to obtain a suspension. S3. Transfer the suspension to a reactor, heat to 75±2℃, maintain the temperature at 500-600 r / min and stir for 2.5 h, transfer to a centrifuge, centrifuge at 8000-10000 r / min for 20 min, collect the precipitate; wash the precipitate 2-3 times with a mixture of deionized water and anhydrous ethanol in a volume ratio of 1:1, and then wash it once with deionized water to remove unreacted modifier; vacuum dry at 80-90℃ and vacuum degree -0.09MPa for 8-10 h, grind it through a 300 mesh sieve to obtain the modified nano-cesium tungsten bronze.

[0009] Furthermore, the curing agent is Wanhua HT-100 DHI trimer curing agent; the dispersant is 445N dispersant; the leveling agent is BYK-333 leveling agent; the defoamer is TEGO 1488 polyether modified silicone; the silane coupling agent is silane coupling agent KH560; the ultraviolet absorber is ultraviolet absorber UV-327; and the film-forming aid is ethylene glycol butyl ether.

[0010] The present invention also provides a method for preparing the functional coating, comprising the following steps: S1. Mix deionized water, dispersant and defoamer, stir at 300-500 r / min for 5-10 min, add modified nano cesium tungsten bronze, heat to 40-50℃, stir and disperse at 1200-1800 r / min for 30-45 min to obtain dispersion slurry; S2. Cool to room temperature, add modified silicone-acrylic emulsion, stir at 500-800 r / min for 15-20 min, then add leveling agent, silane coupling agent, ultraviolet absorber, curing agent and film-forming aid in sequence, and continue stirring for 10-15 min; grind through a 200 mesh sieve to obtain the functional coating.

[0011] This invention also provides a bubble-free composite molding process for tempered laminated glass, comprising the following steps: S1. Apply the functional coating to one side of the first tempered glass and allow it to cure to form a functional coating with a dry film thickness of 8-20 μm; S2. In a lamination chamber with a temperature of 20-25℃ and a relative humidity of 20-30%, lay the first tempered glass with the functional coating facing down, and then stack the PVB interlayer film and the second tempered glass in sequence, aligning the edges to complete the lamination. S3. Feed the laminated glass into a roller press, control the roller pressing temperature to 80-100℃, the roller pressing pressure to 0.3-0.6MPa, and the roller speed to 1.5-3.0m / min, and remove the interlayer air to obtain the preform; S4. Evacuate the preform to -0.095--0.1 MPa and hold the pressure for 10-20 minutes; then heat to 125-135℃ at a rate of 2-3℃ / min, and simultaneously pressurize to 1.0-1.3 MPa, and hold the temperature and pressure for 30-60 minutes; finally, cool to below 40℃ at a rate of 1-2℃ / min and slowly depressurize to atmospheric pressure.

[0012] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention utilizes the crosslinking modification of vinyltriisopropoxysilane and the grafting modification of vinylphosphonic acid to effectively improve the interfacial bonding force between the emulsion film and the glass substrate and functional filler; at the same time, by preparing a modifier from aminotrimethylenephosphonic acid and lanthanum chloride hexahydrate, the surface of nano-cesium tungsten bronze is modified, which solves the technical problem of easy agglomeration of unmodified nano-cesium tungsten bronze and greatly improves its dispersibility in the coating system; in addition, by selecting suitable curing agents, dispersants, leveling agents and other special additives, the efficient compatibility of various components of functional coatings is achieved, laying the foundation for the high performance of functional coatings and tempered laminated glass.

[0013] (2) The functional coating of the present invention has both excellent radiation resistance and high visible light transmittance, achieving a balance between heat insulation and light transmission, effectively avoiding the problem of the decay of core functions such as heat insulation after long-term use; at the same time, the visible light transmittance of the functional coating can be maintained at a high level, so as to achieve the heat insulation modification of glass without significantly affecting the light transmittance of glass, and can meet the actual use needs of glass light transmittance in the construction and other fields.

[0014] (3) The functional coating formed by the coating and curing of the functional coating prepared in this invention has a comprehensive improvement in various physical and chemical properties. The adhesion between the coating and the tempered glass substrate is significantly enhanced, and the wear resistance is excellent. At the same time, the coating has excellent water resistance, weather resistance and resistance to thermal cycling. After 240h water immersion, 1500h artificial accelerated aging and 50 thermal cycles, the gloss loss rate of the coating is controlled at a low level, and the adhesion does not decrease significantly. It can maintain a stable appearance and performance in complex use environments, effectively extending the service life of the coating. Detailed Implementation

[0015] The technical solution of this invention patent will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0016] The silicone-acrylic emulsion used in this application is BF-400B silicone-acrylic emulsion purchased from Zhonghe Chemical (Shandong) Co., Ltd. 1. The Influence of Different Formulations on the Performance of Functional Coatings and Tempered Laminated Glass Products 1.1 Functional Coating Formulation See Table 1 for details.

[0017] Table 1. Formulations of different functional coatings (unit: percentage by mass)

[0018] 1.2 Modified silicone-acrylic emulsion The modified silicone-acrylic emulsion, by weight, is prepared from the following components: 100 parts silicone-acrylic emulsion, 8 parts vinyltriisopropoxysilane, 6 parts vinylphosphonic acid, 0.25 parts azobisisobutyramidine hydrochloride initiator, and 15 parts deionized water. The specific preparation method is as follows: S1. Silicone-acrylic emulsion and deionized water were added to a reactor. Nitrogen gas was introduced for 30 minutes to remove oxygen while stirring at 200 rpm. The temperature was then raised to 75°C and held for 15 minutes. Vinyltriisopropoxysilane was mixed with 70% of the initiator azobisisobutyramidine hydrochloride and added dropwise to the reactor at a rate of 0.1 parts / min. During the dropwise addition, the temperature was maintained at 75±2°C and the stirring speed was 300 rpm. After the dropwise addition was completed, the mixture was stirred at 75°C and 300 rpm for 2.5 hours to obtain a crosslinked modified emulsion intermediate. S2. Add the remaining 30% of the initiator azobisisobutyramidine hydrochloride to the crosslinking modified intermediate, and stir at 75°C and 200 r / min for 10 min; mix vinylphosphonic acid with an equal mass of deionized water and add it dropwise to the reactor at a rate of 0.15 parts / min, maintaining the temperature at 75±2°C and the stirring speed at 300 r / min during the dropwise addition; after the dropwise addition is complete, stir the reaction at 75°C and 300 r / min for 2 h, cool naturally to room temperature, and pass through a 200-mesh sieve to obtain the modified silicone-acrylic emulsion.

[0019] 1.3 Modified Nano-Cesium Tungsten Bronze The specific preparation method is as follows: S1. Weigh aminotrimethylenephosphonic acid and lanthanum chloride hexahydrate at a mass ratio of 1:0.85, and prepare 10% aqueous solutions with water. Slowly add the lanthanum chloride aqueous solution to the aminotrimethylenephosphonic acid aqueous solution at a rate of 1 mL / min, stir at 300 r / min, and adjust the pH to 6.0 with 10% sodium hydroxide solution. Then heat to 60℃, maintain the temperature and stir at 450 r / min for 3 h, cool naturally to room temperature, let stand for 45 min to precipitate, wash the precipitate with deionized water until the pH of the washing solution is 7.0; then vacuum dry the precipitate at 70℃ and -0.09 MPa for 14 h to obtain the modifier. S2. Weigh 20-50nm nano-sized cesium tungsten bronze and modifier at a mass ratio of 100:8; dissolve the modifier in a mixture of deionized water and anhydrous ethanol at a volume ratio of 1:1 to prepare a 5% mass fraction modified solution; add nano-sized cesium tungsten bronze; and ultrasonically disperse at 200W and 25℃ for 30 minutes to obtain a suspension. S3. Transfer the suspension to a reaction vessel, heat to 75±2℃, maintain the temperature at 550r / min and stir for 2.5h, transfer to a centrifuge, centrifuge at 8000r / min for 20min, collect the precipitate; wash the precipitate three times with a 1:1 volume ratio of deionized water and anhydrous ethanol, and then wash it once with deionized water to remove unreacted modifier; vacuum dry at 90℃ and -0.09MPa for 8h, grind through a 300-mesh sieve to obtain the modified nano-cesium tungsten bronze.

[0020] 1.4 Functional Coatings The specific preparation method is as follows: S1. Mix deionized water, dispersant and defoamer, stir at 300-500 r / min for 5-10 min, then add modified nano cesium tungsten bronze (or nano cesium tungsten bronze), heat to 50℃, stir at 1200 r / min for 45 min to obtain dispersion slurry; S2. Cool to room temperature, add modified silicone-acrylic emulsion (or silicone-acrylic emulsion), stir at 600 r / min for 20 min, then add leveling agent, silane coupling agent, ultraviolet absorber, curing agent and film-forming aid in sequence, and continue stirring for 15 min; grind through a 200 mesh sieve to obtain the functional coating.

[0021] 1.5 Bubble-free composite molding process for tempered laminated glass Includes the following steps: S1. Coat one side of the first tempered glass with the functional coating in Table 1, level at room temperature for 5 min, dry with hot air at 60℃ for 60 min, and cure to form a functional coating with a dry film thickness of 15 μm. S2. In a lamination chamber with a temperature of 25℃ and a relative humidity of 25±3%, lay the first tempered glass with the functional coating facing down, and then stack the PVB interlayer film and the second tempered glass in sequence, aligning the edges to complete the lamination. S3. The laminated glass is fed into a roller press, and the roller pressing temperature is controlled at 85℃, the roller pressing pressure at 0.5MPa, and the roller speed at 2.0m / min. The interlayer air is discharged to obtain the preform. S4. Evacuate the preform to -0.095MPa and hold the pressure for 20 minutes; then heat to 135℃ at a rate of 3℃ / min and simultaneously pressurize to 1.3MPa, holding the temperature and pressure for 45 minutes; finally, cool to below 40℃ at a rate of 1.5℃ / min and slowly depressurize to atmospheric pressure.

[0022] 1.6 Performance Testing of Tempered Laminated Glass and Coatings In the samples, the thickness of both the first and second tempered glass was 6 mm, and the thickness of the PVB interlayer was 0.76 mm. For the visible light transmittance and radiation resistance tests, the sample size was 300 mm × 76 mm. For the shotgun bag impact performance test, the sample size was 1930 mm × 864 mm. For the coating performance test, the sample size was 150 mm × 75 mm.

[0023] Table 2. Performance Testing Instructions for Different Formulations of Functional Coatings and Tempered Laminated Glass Products

[0024] Table 3. Performance test results of functional coatings and tempered laminated glass products with different formulations.

[0025] In terms of visible light transmittance, the functional coating blank sample had a transmittance of 89.5%, while GNTL1 had a transmittance of only 76.2% due to the agglomeration of unmodified nano-cesium tungsten bronze. The transmittance of the modified GNTL2 increased to 82.5%, and the transmittance of the emulsion-modified GNTL3 further increased to 86.7%. After adding KH560 to optimize the interface bonding, the transmittance of GNTL4 reached 88.3%, which is close to the level of the blank sample, thus solving the problem of transmittance decrease caused by the addition of heat-insulating powder.

[0026] In terms of radiation resistance, GNTL1, without any modification, showed a transmittance change rate ΔT of 8.7% after 1000h of ultraviolet irradiation, far exceeding the 2.8% of the blank sample. As the modification system of GNTL2-GNTL4 improved, ΔT gradually decreased to 5.3%, 2.5%, and 2.1%, respectively. Among them, GNTL3 and GNTL4 showed better radiation resistance than the blank sample, effectively suppressing ultraviolet photochromism and improving long-term optical stability.

[0027] In terms of impact resistance, GNTL1 had a lower impact height than the blank sample due to poor adhesion between the coating and the glass. As the coating adhesion gradually improved, the impact height of GNTL2, GNTL3 and GNTL4 continued to increase. GNTL4 increased by 18.2% compared to the blank sample and by 23.8% compared to the conventional formulation GNTL1. This shows that the functional coating of this application not only does not affect the safety performance of the glass, but also enhances the impact resistance through strong adhesion.

[0028] In addition, in terms of coating performance, the adhesion between the coating and the tempered glass substrate is significantly enhanced, and the wear resistance is excellent. At the same time, the coating has excellent water resistance, weather resistance and thermal cycling resistance. After 240 hours of water immersion, 1500 hours of artificial accelerated aging and 50 thermal cycles, the gloss loss rate of the coating is controlled at a low level, and the adhesion does not decrease significantly. It can maintain stable appearance and performance in complex use environments, effectively extending the service life of the coating.

[0029] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A functional coating, characterized in that, The functional coating, by mass percentage, is prepared from the following components: 35-60% modified silicone-acrylic emulsion, 8-18% modified nano-cesium tungsten bronze, 3-8% curing agent, 0.4-1.2% dispersant, 0.3-0.8% leveling agent, 0.2-0.6% defoamer, 0.3-0.9% silane coupling agent, 0.3-1.0% ultraviolet absorber, 0.5-2% film-forming aid, and deionized water to bring the total to 100%. The modified silicone-acrylic emulsion, by weight, is prepared from the following components: 100 parts silicone-acrylic emulsion, 4-9 parts vinyltriisopropoxysilane, 2-7 parts vinylphosphonic acid, 0.15-0.35 parts azobisisobutyramidine hydrochloride initiator, and 10-20 parts deionized water.

2. The functional coating according to claim 1, characterized in that, The modified silicone-acrylic emulsion is prepared by: S1. Silicone-acrylic emulsion and deionized water were added to a reactor. Nitrogen gas was introduced for 30 minutes to remove oxygen while stirring at 200 rpm. The temperature was then raised to 75°C and held for 15 minutes. Vinyltriisopropoxysilane was mixed with 70% of the initiator azobisisobutyramidine hydrochloride and added dropwise to the reactor at a rate of 0.05-0.10 parts / min. During the dropwise addition, the temperature was maintained at 75±2°C and the stirring speed was 300 rpm. After the dropwise addition was completed, the mixture was stirred at 75°C and 300 rpm for 2.5 hours to obtain a crosslinked modified emulsion intermediate. S2. Add the remaining 30% of the initiator azobisisobutyramidine hydrochloride to the crosslinking modified intermediate, and stir at 75°C and 200 r / min for 10 min; mix vinylphosphonic acid with an equal mass of deionized water and add it dropwise to the reactor at a rate of 0.15-0.20 parts / min, maintaining the temperature at 75±2°C and the stirring speed at 300 r / min during the dropwise addition; after the dropwise addition is complete, stir the reaction at 75°C and 300 r / min for 2 h, cool naturally to room temperature, and pass through a 200-mesh sieve to obtain the modified silicone-acrylic emulsion.

3. The functional coating according to claim 1, characterized in that, The preparation method of the modified nano-cesium tungsten bronze is as follows: S1. Weigh aminotrimethylenephosphonic acid and lanthanum chloride hexahydrate at a mass ratio of 1:0.85, and prepare 10% aqueous solutions with water. Slowly add the lanthanum chloride aqueous solution to the aminotrimethylenephosphonic acid aqueous solution at a rate of 1 mL / min, stir at 300-400 r / min, and adjust the pH to 5.5-6.0 with 10% sodium hydroxide solution. Then heat to 60℃, maintain the temperature and stir at 400-500 r / min for 3 hours, cool naturally to room temperature, let stand for 30-60 minutes to precipitate, wash the precipitate with deionized water until the pH of the washing solution is 6.5-7.0; then vacuum dry the precipitate at 60-70℃ and -0.09 MPa for 12-16 hours to obtain the modifier. S2. Weigh 20-50 nm nano-sized cesium tungsten bronze and modifier at a mass ratio of 100:5-10; dissolve the modifier in a 1:1 mixture of deionized water and anhydrous ethanol to prepare a 5% mass fraction modified solution; add nano-sized cesium tungsten bronze; and ultrasonically disperse at 150-200 W and 25-35 °C for 30 min to obtain a suspension. S3. Transfer the suspension to a reactor, heat to 75±2℃, maintain the temperature at 500-600 r / min and stir for 2.5 h, transfer to a centrifuge, centrifuge at 8000-10000 r / min for 20 min, collect the precipitate; wash the precipitate 2-3 times with a mixture of deionized water and anhydrous ethanol in a volume ratio of 1:1, and then wash it once with deionized water to remove unreacted modifier; vacuum dry at 80-90℃ and vacuum degree -0.09MPa for 8-10 h, grind it through a 300 mesh sieve to obtain the modified nano-cesium tungsten bronze.

4. The functional coating according to claim 1, characterized in that, The curing agent is Wanhua HT-100 DHI trimer curing agent; the dispersant is 445N dispersant; the leveling agent is BYK-333 leveling agent; the defoamer is TEGO 1488 polyether modified silicone; the silane coupling agent is silane coupling agent KH560; the ultraviolet absorber is ultraviolet absorber UV-327; and the film-forming aid is ethylene glycol butyl ether.

5. A method for preparing the functional coating according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Mix deionized water, dispersant and defoamer, stir at 300-500 r / min for 5-10 min, add modified nano cesium tungsten bronze, heat to 40-50℃, stir and disperse at 1200-1800 r / min for 30-45 min to obtain dispersion slurry; S2. Cool to room temperature, add modified silicone-acrylic emulsion, stir at 500-800 r / min for 15-20 min, then add leveling agent, silane coupling agent, ultraviolet absorber, curing agent and film-forming aid in sequence, and continue stirring for 10-15 min; The functional coating is obtained by grinding the material through a 200-mesh sieve.

6. A bubble-free composite molding process for tempered laminated glass, characterized in that, Includes the following steps: S1. Coat one side of the first tempered glass with the functional coating of claim 1, and allow it to cure to form a functional coating with a dry film thickness of 8-20 μm; S2. In a lamination chamber with a temperature of 20-25℃ and a relative humidity of 20-30%, lay the first tempered glass with the functional coating facing down, and then stack the PVB interlayer film and the second tempered glass in sequence, aligning the edges to complete the lamination. S3. Feed the laminated glass into a roller press, control the roller pressing temperature to 80-100℃, the roller pressing pressure to 0.3-0.6MPa, and the roller speed to 1.5-3.0m / min, and remove the interlayer air to obtain the preform; S4. Evacuate the preform to -0.095--0.1 MPa and hold the pressure for 10-20 minutes; then heat to 125-135℃ at a rate of 2-3℃ / min, and simultaneously pressurize to 1.0-1.3 MPa, and hold the temperature and pressure for 30-60 minutes; finally, cool to below 40℃ at a rate of 1-2℃ / min and slowly depressurize to atmospheric pressure.

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