PVC decorative film multi-layer composite processing method based on heat resistance

Abstract

The invention relates to the technical field of design and processing of PVC (polyvinyl chloride) composite materials, in particular to a multi-layer composite processing method of a PVC decorative film based on heat resistance, which comprises the following steps: firstly, preparing PVC resin powder, various additives and a nano modified additive, premixing and mainly mixing the raw materials, uniformly mixing under the protection of nitrogen, plasticizing and extruding by using a double-screw extruder, and carrying out extrusion molding to obtain the PVC decorative film based on heat resistance. Surface treatment including plasma and chemical etching is carried out after extrusion, then a modified polyurethane bonding layer containing a silane coupling agent is coated and compounded with a micro-nano structure PET decorative film, ultrasonic vibration is applied, then hot-pressing shaping is carried out, a hot-pressing roller is provided with micro textures, finally cooling and rolling are carried out, and all the steps have specific parameters. According to the method, the effect is remarkable, the heat resistance of the PVC decorative film is greatly improved, the heat deformation temperature is increased, the processing performance is optimized, the production efficiency is improved, the bonding and compounding effect is enhanced, the decorative layer is not prone to falling off, the environmental protection property and the product attractiveness are further improved, and the market competitiveness is enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of design and processing of PVC composite materials, in particular to a multi-layer composite processing method of a PVC decorative film based on heat resistance. Background Art

[0002] PVC decorative film has been widely used in a variety of fields, including architectural decoration and furniture manufacturing, due to its rich colors, diverse patterns, and excellent decorative effects. However, with the development of the industry and the diversification of usage environments, higher requirements have been placed on the heat resistance of PVC decorative film. Existing PVC decorative film has many shortcomings in this regard.

[0003] Traditional PVC decorative films have limited heat resistance. PVC materials themselves have poor thermal stability and are prone to degradation in high-temperature environments, leading to discoloration, deformation, and decreased mechanical properties. For example, in interior decoration in buildings located in high-temperature regions, or on furniture exposed to long-term direct sunlight, PVC decorative films can gradually turn yellow, lose their luster, and even blister and peel, severely impacting the decorative effect and service life. This is primarily due to the mediocre performance of additives such as plasticizers and stabilizers used in the formulation of traditional PVC decorative films, which cannot effectively inhibit PVC degradation reactions at high temperatures.

[0004] From a raw material perspective, traditional PVC decorative films mostly use a single plasticizer, such as dioctyl phthalate (DOP). This volatile agent easily evaporates at high temperatures, reducing the film's flexibility and plasticity while also releasing harmful gases that pose a threat to human health and the environment. Furthermore, traditional stabilizer systems, such as calcium-zinc stabilizers, offer suboptimal thermal stability when used alone and cannot meet the requirements of long-term high-temperature use. Regarding fillers, conventional calcium carbonate has a large particle size and poor dispersibility, which not only fails to effectively enhance the film's heat resistance but can also affect its mechanical and processing properties.

[0005] Existing PVC decorative film processing methods also have certain limitations. During the plasticizing and extrusion process, insufficient plasticization uniformity and dispersion of the material can lead to an uneven internal structure of the decorative film, impacting its overall performance. For example, improper control of the plasticizing temperature and screw speed can cause localized poor plasticization, significantly compromising the decorative film's stability and mechanical properties at high temperatures.

[0006] Furthermore, surface treatment and lamination processes need improvement. Traditional surface treatments, such as simple corona treatment, offer limited improvement in the surface adhesion of decorative films. Lamination with the decorative layer can lead to weak adhesion and, in high-temperature environments, can easily cause the decorative layer to fall off. Furthermore, most existing lamination processes fail to account for differences in thermal expansion coefficients between different materials. Temperature fluctuations can generate internal stresses, accelerating damage to the decorative film.

[0007] In practical applications, rising building energy-saving standards and increasingly stringent furniture environmental requirements are posing greater challenges to the heat resistance, environmental performance, and service life of PVC decorative films. For example, in public space renovations requiring high fire and heat resistance, traditional PVC decorative films struggle to meet fire safety standards. In furniture manufacturing, achieving green and environmentally friendly production requires reducing the use of harmful additives in decorative films while ensuring that their performance remains intact. This presents new challenges for the research and development and production of PVC decorative films. Therefore, the development of a multi-layer composite processing method for PVC decorative films based on heat resistance is urgent to address the numerous challenges of existing technologies and meet market demand for high-performance PVC decorative films. Summary of the Invention

[0008] In view of the deficiencies in the prior art, the present invention provides a multi-layer composite processing method for PVC decorative films based on heat resistance.

[0009] A multi-layer composite processing method for PVC decorative film based on heat resistance comprises the following steps: S1, raw material preparation: prepare PVC resin powder, plasticizer, stabilizer, lubricant, new heat-resistant enhancer, antioxidant, filler and nano-modified additive; the new heat-resistant enhancer is produced by condensation reaction of 4-hydroxy-3-methoxyphenol and maleimide, reaction formula: , The plasticizer is composed of dioctyl phthalate DOP, epoxidized soybean oil ESO and a new plasticizer X. The structural formula of the plasticizer X is: , The stabilizer is a compound of calcium zinc composite stabilizer and a new type of heat stabilizing synergist Y, and the structural formula of Y is: , The lubricant is a mixture of stearic acid, polyethylene wax and lubricant Z, wherein Z is prepared by grafting zinc stearate onto the surface of nano-silicon dioxide; the antioxidant is a compound of hindered phenol antioxidant 1010 and thioester antioxidant 168; the filler is calcium carbonate with a surface treated with a silane coupling agent; and the nano-modified additive is nano-montmorillonite; S2, mixing: add the raw materials into a high-speed mixer, pre-mix at 50-60°C, then heat to 100-120°C and mix, using nitrogen protection during the mixing process; S3, plasticizing and extruding: add the mixed raw materials into the twin-screw extruder; the temperature of zone 1 is 150-160℃, zone 2 is 160-170℃, zone 3 is 170-180℃, zone 4 is 180-190℃, the head temperature is 190-200℃, and the screw speed is 30-50r / min; S4, surface treatment: first treat with plasma at a power of 2-4kW for 3-5 minutes; then immerse the base film in a dilute hydrochloric acid solution with a mass fraction of 0.5%-1% for etching for 2-4 minutes; S5, coating the bonding layer: coating the surface of the treated PVC base film with a bonding layer of polyurethane adhesive modified with a silane coupling agent, with a coating amount of 5-10g / m²; S6, composite decorative layer: an optical-grade PET film with a micro-nano structure is used as the decorative layer material, composited with a PVC base film coated with an adhesive layer, and ultrasonic vibration is applied; S7, hot pressing and shaping: send the composite PVC decorative film into the hot pressing roller for hot pressing and shaping, the hot pressing temperature is 120-140℃, and the pressure is 1-2MPa; S8, cooling and winding: The PVC decorative film after hot pressing and shaping is cooled by a cooling roller, and a circulating cooling medium is passed into the cooling roller.

[0010] Preferably, the method further comprises, in the step S1 of preparing raw materials, performing an organic treatment on the nano-montmorillonite and performing intercalation modification on the nano-montmorillonite using a quaternary ammonium salt cationic surfactant.

[0011] Preferably, after the plasticizing and extruding step S3, the extruded PVC base film is subjected to an online stretching treatment, with a stretching ratio of 1.2-1.5.

[0012] Preferably, in step S1, the degree of polymerization of the PVC resin powder is 1000-1200.

[0013] Preferably, in step S1, the mass ratio of DOP, ESO and plasticizer X is 3:1:0.5.

[0014] Preferably, in step S2, the premixing temperature of the high-speed mixer is 55-60° C., the premixing time is 6-8 minutes, and the mixing temperature after heating is 105-115° C., and the mixing time is 12-14 minutes.

[0015] Preferably, in step S3, the temperature of the twin-screw extruder zone 1 is 155-160°C, the temperature of the zone 2 is 165-170°C, the temperature of the zone 3 is 175-180°C, the temperature of the zone 4 is 185-190°C, and the head temperature is 195-200°C.

[0016] Preferably, in step S4, the plasma treatment power is 2.5-3.5 kW, the treatment time is 4-5 minutes, the mass fraction of the dilute hydrochloric acid solution during chemical etching is 0.6%-0.8%, and the etching time is 3-4 minutes.

[0017] Preferably, in step S5, the coating amount of the adhesive layer is 6-8 g / m².

[0018] Preferably, in step S7, the depth of the micro-texture structure on the surface of the hot pressing roller is 5-10 μm, the hot pressing temperature is 125-135° C., the pressure is 1.2-1.8 MPa, and the time is 6-8 seconds.

[0019] Compared with the existing technology, the beneficial effects of the present invention are: 1. By adding a new heat-resistant enhancer, it chemically reacts with PVC molecular chains, enhancing interactions between the chains and effectively raising the thermal decomposition temperature of the decorative film. Simultaneously, the addition of a new plasticizer X, a heat-stabilizing synergist Y, and nano-montmorillonite synergistically enhances the decorative film's heat resistance. Testing has shown that compared to traditional PVC decorative films, the product of this invention exhibits a higher heat deformation temperature and maintains excellent physical properties even after prolonged exposure to temperatures of 120°C. This significantly broadens its application and meets decorative needs in high-temperature environments.

[0020] 2. Premixing and nitrogen protection measures in the high-speed mixer, along with new mixing elements in the twin-screw extruder, ensure more uniform mixing and more complete plasticization of the raw materials. In-line stretching further improves the internal structure of the PVC base film and enhances its mechanical properties. These improvements result in a more stable process, increased production efficiency, more reliable product quality, and a lower defective rate.

[0021] 3. A surface treatment method combining plasma treatment and chemical etching significantly improves the surface activity and roughness of the PVC base film. Combined with a polyurethane adhesive modified with a silane coupling agent, the bond strength between the decorative layer and the base film is enhanced. Ultrasonic vibration applied during the lamination process further strengthens the bond, making the decorative layer less susceptible to detachment even in harsh environments such as high temperature and high humidity.

[0022] 4. The use of the new plasticizer X reduces the use of traditional plasticizers and reduces the emission of harmful gases. Furthermore, the addition of nano-montmorillonite improves performance while reducing the use of other additives, making the product more environmentally friendly. The micro-textured surface of the hot pressing roller and the optical-grade PET decorative layer with micro-nanostructures not only enhance the tactile and visual effects of the decorative film, but also impart unique optical properties, such as diffuse reflection, which creates an aesthetically pleasing effect at different angles, enhancing the product's market competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of a multi-layer composite processing method of PVC decorative film based on heat resistance proposed by the present invention; Figure 2 It is a bar chart comparing the heat deformation temperatures of the embodiment and the comparative example; Figure 3 is a line chart comparing the bonding strengths of the embodiment and the comparative example; Figure 4 1. It is a comparison chart of tensile strength and elongation at break of the embodiment and the comparative example; Figure 5 This is a radar comparison chart produced after unifying the dimensions of the performance tests of the embodiment and the comparative example. DETAILED DESCRIPTION

[0024] according to Figures 1 to 5 , the specific implementation methods of the present invention are as follows: Example 1, S1 Raw Materials Preparation: 100 parts of PVC resin powder with a degree of polymerization of 1000. Plasticizers used were dioctyl phthalate (DOP), epoxidized soybean oil (ESO), and new plasticizer X in a mass ratio of 3:1:0.5, with a usage of 35 parts.

[0025] The stabilizer is a mixture of 4 parts of calcium zinc composite stabilizer and 0.5 parts of new heat stabilizing synergist Y. The lubricant is a mixture of stearic acid, polyethylene wax and nano-silicon dioxide modified lubricant Z in a ratio of 2:1:0.3, with a dosage of 1 part.

[0026] The new heat-resistant enhancer is used in an amount of 6 parts. The antioxidant is a 1:1 mixture of hindered phenol antioxidant 1010 and thioester antioxidant 168, used in an amount of 0.3 parts. The filler is calcium carbonate surface-treated with a silane coupling agent, with a particle size of 1500 mesh, used in an amount of 15 parts. The nano-modified additive, nano-montmorillonite, is used in an amount of 2 parts.

[0027] S2 Mixing: Add the above ingredients to a high-speed mixer and premix at 55°C for 6 minutes. During this process, activate the nitrogen protection device and allow nitrogen to flow into the mixer at a rate of 0.5m³ / h. Then, raise the temperature to 105°C and continue mixing for 12 minutes to ensure that the ingredients are fully and evenly mixed.

[0028] S3 Plasticizing and Extrusion: The mixed raw materials are fed into a twin-screw extruder equipped with a new mixing element. Zone 1 temperature is set at 155°C, Zone 2 at 165°C, Zone 3 at 175°C, and Zone 4 at 185°C. The die head temperature is set at 195°C, and the screw speed is set at 40 rpm. The PVC base film is extruded. After extrusion, the base film is stretched online with a stretch ratio of 1.3.

[0029] S4 Surface Treatment: The PVC base film was first treated with plasma at 2.5 kW for 4 minutes using a 4:1 volume ratio of argon and oxygen. The base film was then immersed in a 0.6% by mass dilute hydrochloric acid solution for 3 minutes to improve the surface roughness and activity.

[0030] S5: Apply adhesive layer: Use polyurethane adhesive modified with silane coupling agent to apply on the surface of the surface-treated PVC base film. The coating amount is controlled at 6g / m² to ensure that the adhesive evenly covers the surface of the base film.

[0031] S6 composite decorative layer: The decorative layer uses optical-grade PET film with micro-nano structures, and the surface micro-nanostructure is produced through nanoimprinting technology. During the composite process, ultrasonic vibrations at a frequency of 25kHz are applied, the composite pressure is 0.6MPa, and the composite speed is 4m / min.

[0032] S7 hot pressing: The laminated PVC decorative film is fed into a hot pressing roller with a micro-texture structure (depth of 7μm) on the surface. The hot pressing temperature is set to 125℃, the pressure is 1.2MPa, and the hot pressing time is 6 seconds to form a unique texture on the surface of the decorative film.

[0033] S8 Cooling and Rewinding: The PVC decorative film after hot pressing and shaping is cooled by a cooling roller. Circulating cooling water is passed into the cooling roller and the temperature is controlled at 22°C. After cooling, it is rewound to obtain the final PVC decorative film product.

[0034] Example 2, S1 raw material preparation: PVC resin powder with a degree of polymerization of 1100, used in an amount of 100 parts. Plasticizer used in an amount of 40 parts, the proportions are the same as in Example 1.

[0035] 5 parts of calcium zinc composite stabilizer, 0.8 parts of heat stability synergist Y, 1.5 parts of lubricant, 8 parts of new heat-resistant enhancer, 0.4 parts of antioxidant, 18 parts of filler particle size 1800 mesh, and 2.5 parts of nano-montmorillonite.

[0036] S2 mixing: premixing temperature 58°C, time 7 minutes, nitrogen flow rate 0.6m³ / h, main mixing temperature 110°C, time 13 minutes.

[0037] S3 plasticizing extrusion: zone 1 temperature 158°C, zone 2 168°C, zone 3 178°C, zone 4 188°C, die head temperature 198°C, screw speed 45r / min, stretching ratio 1.4.

[0038] S4 surface treatment: plasma treatment power 3kW, time 4.5 minutes, dilute hydrochloric acid mass fraction 0.7%, etching time 3.5 minutes.

[0039] S5 coating adhesive layer: coating amount 7g / m².

[0040] S6 composite decorative layer: ultrasonic frequency 28kHz, composite pressure 0.8MPa, composite speed 5m / min.

[0041] S7 hot pressing setting: hot pressing roller micro texture depth 8μm, temperature 130℃, pressure 1.5MPa, time 7 seconds.

[0042] S8 cooling and coiling: cooling temperature 25℃.

[0043] Example 3, S1 raw material preparation: PVC resin powder with a degree of polymerization of 1200, used in an amount of 100 parts. Plasticizer used in an amount of 45 parts, the proportion remains unchanged.

[0044] 6 parts of calcium zinc composite stabilizer, 1 part of heat stability synergist Y, 2 parts of lubricant, 10 parts of new heat resistance enhancer, 0.5 parts of antioxidant, 20 parts of filler particle size 2000 mesh, and 3 parts of nano-montmorillonite.

[0045] S2 mixing: premixing temperature 60℃, time 8 minutes, nitrogen flow rate 0.7m³ / h, main mixing temperature 115℃, time 14 minutes.

[0046] S3 plasticizing extrusion: zone 1 temperature 160℃, zone 2 170℃, zone 3 180℃, zone 4 190℃, die head temperature 200℃, screw speed 50r / min, stretching ratio 1.5.

[0047] S4 surface treatment: plasma treatment power 3.5kW, time 5 minutes, dilute hydrochloric acid mass fraction 0.8%, etching time 4 minutes.

[0048] S5 coating adhesive layer: coating amount 8g / m².

[0049] S6 composite decorative layer: ultrasonic frequency 30kHz, composite pressure 1MPa, composite speed 6m / min.

[0050] S7 hot pressing setting: hot pressing roller micro texture depth 10μm, temperature 135℃, pressure 1.8MPa, time 8s.

[0051] S8 cooling and coiling: cooling temperature 28℃.

[0052] Comparative Example, S1 Raw Materials Preparation: Traditional PVC resin powder with a degree of polymerization of 800 was used, using 100 parts. The plasticizer used was dioctyl phthalate (DOP) (30 parts), the stabilizer was a standard calcium zinc stabilizer (3 parts), and the lubricant was stearic acid (0.5 parts). No new heat-resistant enhancer, heat-stabilizing synergist Y, nano-silica-modified lubricant Z, or nano-montmorillonite were added. The antioxidant used was a single hindered phenol antioxidant, 1010, using 0.2 parts. The filler was standard calcium carbonate, 1000 mesh, using 10 parts.

[0053] S2 mixing: Add the raw materials into a common mixer and mix them at 80°C for 10 minutes without nitrogen protection.

[0054] S3 plasticizing extrusion: using a common twin-screw extruder, the temperature of zone 1 was 140°C, zone 2 was 150°C, zone 3 was 160°C, zone 4 was 170°C, the head temperature was 180°C, the screw speed was 20 r / min, and no online stretching treatment was performed.

[0055] S4 surface treatment: Only simple corona treatment is performed on the PVC base film.

[0056] S5 coating bonding layer: Use ordinary polyurethane adhesive for coating, with a coating amount of 5g / m².

[0057] S6 composite decorative layer: The decorative layer is ordinary PET film. No ultrasonic vibration is applied during the composite process. The composite pressure is 0.3 MPa and the composite speed is 2 m / min.

[0058] S7 hot pressing: The surface of the hot pressing roller has no special texture, the hot pressing temperature is 100℃, the pressure is 0.5MPa, and the time is 3 seconds.

[0059] S8 cooling and coiling: cooling temperature 30℃.

[0060] Performance tests were conducted on the PVC decorative films prepared in the above examples and comparative examples. The results showed that the decorative films prepared in the examples were significantly superior to the comparative examples in terms of heat resistance, bonding strength, mechanical properties and appearance, fully demonstrating the advantages of the processing method of the present invention.

[0061] The raw material formula of the embodiment and the comparative example is compared in the following table: , Conclusion: This table visually demonstrates the differences in raw material formulations between the Examples and the Comparative Examples. Different raw material amounts and specifications are fundamental factors leading to varying final product properties. It can be seen that the Examples utilize a richer and higher-quality selection of raw materials, incorporating novel additives, while the Comparative Examples utilize traditional raw materials in smaller quantities.

[0062] The performance test comparison of the embodiment and the comparative example is shown in the following table: , Conclusion: This table compares the key performance indicators of the Examples and Comparative Examples. The heat deformation temperature, bond strength, tensile strength, and elongation at break of the Examples are significantly higher than those of the Comparative Examples, demonstrating that the processing method and raw material formulation of this invention effectively improve the performance of PVC decorative film.

[0063] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A multi-layer composite processing method for PVC decorative film based on heat resistance, characterized in that: The following steps are involved: S1, raw material preparation: prepare PVC resin powder, plasticizer, stabilizer, lubricant, new heat-resistant enhancer, antioxidant, filler and nano-modified additive; the new heat-resistant enhancer is produced by condensation reaction of 4-hydroxy-3-methoxyphenol and maleimide, reaction formula: ， The plasticizer is composed of dioctyl phthalate DOP, epoxidized soybean oil ESO and a new plasticizer X. The structural formula of the plasticizer X is: ， The stabilizer is a compound of calcium zinc composite stabilizer and a new type of heat stabilizing synergist Y, and the structural formula of Y is: ， The lubricant is a mixture of stearic acid, polyethylene wax and lubricant Z, wherein Z is prepared by grafting zinc stearate onto the surface of nano-silicon dioxide; the antioxidant is a compound of hindered phenol antioxidant 1010 and thioester antioxidant 168; the filler is calcium carbonate with a surface treated with a silane coupling agent; and the nano-modified additive is nano-montmorillonite; S2, mixing: add the raw materials into a high-speed mixer, pre-mix at 50-60°C, then heat to 100-120°C and mix, using nitrogen protection during the mixing process; S3, plasticizing and extruding: add the mixed raw materials into the twin-screw extruder; the temperature of zone 1 is 150-160℃, zone 2 is 160-170℃, zone 3 is 170-180℃, zone 4 is 180-190℃, the head temperature is 190-200℃, and the screw speed is 30-50r / min; S4, surface treatment: first treat with plasma at a power of 2-4kW for 3-5 minutes; then immerse the base film in a dilute hydrochloric acid solution with a mass fraction of 0.5%-1% for etching for 2-4 minutes; S5, coating the bonding layer: coating the surface of the treated PVC base film with a bonding layer of polyurethane adhesive modified with a silane coupling agent, with a coating amount of 5-10g / m²; S6, composite decorative layer: an optical-grade PET film with a micro-nano structure is used as the decorative layer material, composited with a PVC base film coated with an adhesive layer, and ultrasonic vibration is applied; S7, hot pressing and shaping: send the composite PVC decorative film into the hot pressing roller for hot pressing and shaping, the hot pressing temperature is 120-140℃, and the pressure is 1-2MPa; S8, cooling and winding: The PVC decorative film after hot pressing and shaping is cooled by a cooling roller, and a circulating cooling medium is passed into the cooling roller.

2. The multi-layer composite processing method of PVC decorative film based on heat resistance according to claim 1, characterized in that: The method further includes, in the step of preparing raw materials S1, performing organic treatment on the nano-montmorillonite and performing intercalation modification on the nano-montmorillonite by using a quaternary ammonium salt cationic surfactant.

3. The multi-layer composite processing method of PVC decorative film based on heat resistance according to claim 1, characterized in that: The method further includes performing an online stretching treatment on the extruded PVC base film after the S3 plasticizing and extruding step, with a stretching ratio of 1.2-1.

5.

4. The multi-layer composite processing method of PVC decorative film based on heat resistance according to claim 1, characterized in that: In step S1, the degree of polymerization of the PVC resin powder is 1000-1200.

5. The multi-layer composite processing method of PVC decorative film based on heat resistance according to claim 1, characterized in that: In step S1, the mass ratio of DOP, ESO, and plasticizer X is 3:1:0.

5.

6. The multi-layer composite processing method of PVC decorative film based on heat resistance according to claim 1, characterized in that: In step S2, the premixing temperature of the high-speed mixer is 55-60° C., the premixing time is 6-8 minutes, and the mixing temperature after heating is 105-115° C., and the mixing time is 12-14 minutes.

7. The multi-layer composite processing method of PVC decorative film based on heat resistance according to claim 1, characterized in that: In step S3, the temperature of the twin-screw extruder zone 1 is 155-160°C, the temperature of the zone 2 is 165-170°C, the temperature of the zone 3 is 175-180°C, the temperature of the zone 4 is 185-190°C, and the head temperature is 195-200°C.

8. The multi-layer composite processing method of PVC decorative film based on heat resistance according to claim 1, characterized in that: In step S4, the plasma treatment power is 2.5-3.5 kW, the treatment time is 4-5 minutes, the mass fraction of the dilute hydrochloric acid solution during chemical etching is 0.6%-0.8%, and the etching time is 3-4 minutes.

9. The multi-layer composite processing method of PVC decorative film based on heat resistance according to claim 1, characterized in that: In step S5, the coating amount of the adhesive layer is 6-8 g / m².

10. The multi-layer composite processing method of PVC decorative film based on heat resistance according to claim 1, characterized in that: In step S7, the depth of the micro-texture structure on the surface of the hot pressing roller is 5-10 μm, the hot pressing temperature is 125-135° C., the pressure is 1.2-1.8 MPa, and the time is 6-8 seconds.

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