Tear-resistant and moisture-proof desiccant packaging material and production method thereof

Abstract

The present invention relates to the technical field of desiccant packaging materials, and in particular to a tear-resistant and moisture-proof desiccant packaging material and a production method thereof. The tear-resistant and moisture-proof desiccant packaging material comprises: a polyester non-woven fabric, and a polypropylene film and a polyethylene film respectively attached to both sides of the polyester non-woven fabric; the raw materials of the polyester non-woven fabric comprise: polyester fibers and prefabricated fibers. The polyester non-woven fabric is prepared by the following specific operations: prefabricated fibers are dispersed on the mesh curtain of the mesh machine to form a bottom layer, and then the polyester fibers are evenly dispersed on the surface of the bottom layer to form an intermediate layer, and then the prefabricated fibers are dispersed on the surface of the intermediate layer to form a surface layer, and then hydroentangled. Theoretically, without glue, hot pressing alone cannot achieve good composite strength. The present invention enhances the strength of the packaging material in a specific way. At the same time, the product is environmentally friendly and efficient, and improves the problems of water seepage and powder leakage of the desiccant packaging material. Compared with products on the market, the present invention has stronger tear resistance and improves the quality of the packaging material.

Description

Technical Field

[0001] The present invention relates to the technical field of desiccant packaging materials, in particular to a tear-resistant and moisture-proof desiccant packaging material and a production method thereof. Background Art

[0002] Desiccant is a substance that removes moisture from moist materials and is generally categorized as either chemical or physical. Chemical desiccants (such as calcium sulfate and calcium chloride) dry by combining with water to form hydrates, while physical desiccants (such as silica gel and montmorillonite) dry by physically adsorbing water.

[0003] However, desiccant cannot come into direct contact with the product and must be protected by desiccant packaging materials. Currently, there are many different types of desiccant packaging materials, each with its own advantages and disadvantages. When selecting packaging materials, it's important to consider the type of desiccant, its intended use, and the desired protective properties. For applications requiring high moisture resistance, polyester film is an option, while for applications requiring high strength and breathability, non-woven fabrics are a better choice.

[0004] In the prior art, glue is often used to bond the layers of film or cloth-based materials. Although this can give the packaging material good tear strength, the polyester film has poor air permeability, which easily leads to poor water absorption of the packaging material. If exposed to ultraviolet rays, the polyester film is easily aged, resulting in powder leakage of the packaging material.

[0005] With the rapid development of social economy and the continuous improvement of living standards, people have increasingly higher requirements for desiccant packaging materials. The air permeability, tear resistance and anti-aging performance have become issues of concern to people.

[0006] Therefore, it is urgent to develop a desiccant packaging material that not only needs to have good mechanical properties and excellent tear resistance, but also be breathable and moisture-permeable, resistant to aging, and avoid powder leakage. Summary of the Invention

[0007] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a tear-resistant and moisture-proof desiccant packaging material and a production method thereof.

[0008] A tear-resistant and moisture-proof desiccant packaging material comprises: a polyester non-woven fabric, and a polypropylene film and a polyethylene film respectively attached to both sides of the polyester non-woven fabric; wherein the polypropylene film and the polyethylene film are both provided with through holes; the raw materials of the polyester non-woven fabric comprise: polyester fiber and prefabricated fiber; the mass ratio of the polyester fiber to the prefabricated fiber is 30-60:20-40.

[0009] Preferably, the thickness of the polyester non-woven fabric is 20-60 μm, the thickness of the polypropylene film is 20-40 μm, and the thickness of the polyethylene film is 10-40 μm.

[0010] Preferably, the polyethylene film is made of linear low-density polyethylene.

[0011] Preferably, the polyester nonwoven fabric is produced by the following specific operations: prefabricated fibers are dispersed on a mesh curtain to form a bottom layer, polyester fibers are evenly dispersed on the surface of the bottom layer to form a middle layer, and then prefabricated fibers are dispersed on the surface of the middle layer to form a surface layer, and hydroentangled.

[0012] Preferably, the mass ratio of the prefabricated fibers used in the bottom layer to the prefabricated fibers used in the surface layer is 10-20:10-20.

[0013] Preferably, the prefabricated fiber has a diameter of 0.10-0.45 mm.

[0014] Preferably, the prefabricated fiber is prepared by the following specific operation: adding polyvinyl alcohol to water, stirring at 70-80°C for 1-2 hours, adjusting the pH value of the system to 8-9, keeping warm for 10-30 minutes, adding graphene oxide and epichlorohydrin, stirring at 70-80°C for 1-2 hours, adjusting the system to neutral, freeze-drying, and melt spinning.

[0015] Preferably, the mass ratio of polyvinyl alcohol, graphene oxide and epichlorohydrin is 1-5:1-5:0.1-1.

[0016] The production method of the tear-resistant and moisture-proof desiccant packaging material comprises the following steps: laminating a polypropylene film on one side of a polyester non-woven fabric, laminating a polyethylene film on the other side of the polyester non-woven fabric, hot pressing, and cooling to room temperature.

[0017] Preferably, the hot pressing temperature is 90-100° C., the hot pressing pressure is 0.4-0.5 MPa, and the hot pressing time is 2-6 s.

[0018] Beneficial effects:

[0019] Because polyvinyl alcohol contains a large number of hydroxyl groups, it has strong hydrophilicity. The present invention utilizes graphene oxide grafted onto polyvinyl alcohol, significantly enhancing the stability of the prefabricated fiber under the action of epichlorohydrin. The prefabricated fiber, combined with a large amount of lamellar graphene, not only exhibits excellent air and moisture permeability but also maintains excellent mechanical strength even after absorbing water.

[0020] The present invention lays polyester fiber in the middle and prefabricated fibers on both sides to prepare a polyester non-woven fabric, so that the polyester non-woven fabric not only has a good hot pressing effect with polypropylene film and polyethylene film, but also has extremely high mutual bonding strength, high heat sealing strength, and good tear resistance. At the same time, it has excellent tear resistance even in a humid environment, and can significantly enhance the anti-ultraviolet function of the packaging material, effectively prevent the aging phenomenon of the desiccant packaging, effectively solve the problems existing in the current desiccant packaging materials, and is suitable for large-scale promotion and use.

[0021] The invention effectively avoids the use of glue, the product is environmentally friendly and efficient, and at the same time improves the problems of water seepage and powder leakage of desiccant packaging materials, enhances the strength of the packaging materials, has stronger tear resistance compared with products on the market, and improves the quality of the packaging materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a comparison chart of the puncture resistance and peel strength of the packaging materials obtained in Example 5 and Comparative Examples 1-2.

[0023] Figure 2 This is a comparison chart of the longitudinal / transverse tear strength of the packaging materials obtained in Example 5 and Comparative Examples 1-2.

[0024] Figure 3 This is a comparison chart of the tear strength retention rate of the packaging materials obtained in Example 5 and Comparative Examples 1-2 after water immersion treatment and UV aging treatment.

[0025] Figure 4 The figure is a comparison of the air permeability and moisture permeability of the packaging materials obtained in Example 5 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0026] The present invention will be further explained below with reference to specific embodiments.

[0027] The polyethylene film used below was purchased from Langfang Quan Environmental Protection Technology Co., Ltd. The diameter of its micropores was 0.10 mm, and the distance between two adjacent micropores was 0.20 mm.

[0028] The polypropylene film used below was purchased from Hebei Moupeng Energy Saving Technology Co., Ltd., with a micropore diameter of 0.40 mm and a pore distance of 1.00 mm between two adjacent micropores.

[0029] Example 1

[0030] A tear-resistant, moisture-resistant desiccant packaging material comprising a 20-μm-thick polyester non-woven fabric, and polypropylene and polyethylene films adhered to either side of the polyester non-woven fabric. The polypropylene film is 20 μm thick, and the polyethylene film is 10 μm thick. The polyethylene film is made of linear low-density polyethylene.

[0031] The raw materials of the polyester non-woven fabric include: polyester fiber and prefabricated fiber with a diameter of 0.10 mm; the mass ratio of the polyester fiber to the prefabricated fiber is 30:20.

[0032] The polyester non-woven fabric is prepared by the following specific operations: 100g of prefabricated fibers are dispersed on a mesh curtain to form a bottom layer, 300g of polyester fibers are evenly dispersed on the surface of the bottom layer to form a middle layer, 100g of prefabricated fibers are dispersed on the surface layer, and hydroentangled for reinforcement.

[0033] The prefabricated fiber was prepared by the following specific operation: 100g of polyvinyl alcohol was added to 1000g of water, stirred at a temperature of 70°C for 1h, the pH value of the system was adjusted to 8-9 with a 1mol / L sodium hydroxide solution, and kept warm for 10min, 100g of graphene oxide and 10g of epichlorohydrin were added thereto, stirred at a temperature of 70°C for 1h, hydrochloric acid was used to adjust the system to neutral, freeze-dried, and melt-spun using a single-screw spinning equipment.

[0034] A method for producing tear-resistant and moisture-proof desiccant packaging material comprises the following steps: laminating a polypropylene film on one side of a polyester non-woven fabric, laminating a polyethylene film on the other side of the polyester non-woven fabric, hot pressing at 90° C. for 2 seconds at a pressure of 0.4 MPa, and cooling to room temperature.

[0035] Example 2

[0036] A tear-resistant, moisture-resistant desiccant packaging material comprising a 60μm-thick polyester non-woven fabric, and polypropylene and polyethylene films adhered to either side of the polyester non-woven fabric. The polypropylene film is 40μm thick, and the polyethylene film is 40μm thick. The polyethylene film is made of linear low-density polyethylene.

[0037] The raw materials of the polyester non-woven fabric include: polyester fiber and prefabricated fiber with a diameter of 0.45 mm; the mass ratio of the polyester fiber to the prefabricated fiber is 60:40.

[0038] The polyester non-woven fabric is prepared by the following specific operations: 200g of prefabricated fibers are dispersed on a mesh curtain to form a bottom layer, 600g of polyester fibers are evenly dispersed on the surface of the bottom layer to form a middle layer, 200g of prefabricated fibers are dispersed on the surface layer, and hydroentangled for reinforcement.

[0039] The prefabricated fiber was prepared by the following specific operation: 200g of polyvinyl alcohol was added to 1200g of water, stirred at 80°C for 2h, the pH value of the system was adjusted to 8-9 with a 2mol / L sodium hydroxide solution, and kept warm for 30min, 200g of graphene oxide and 40g of epichlorohydrin were added thereto, stirred at 80°C for 2h, hydrochloric acid was used to adjust the system to neutral, freeze-dried, and melt-spun using a single-screw spinning equipment.

[0040] A method for producing tear-resistant and moisture-proof desiccant packaging material comprises the following steps: laminating a polypropylene film on one side of a polyester non-woven fabric, laminating a polyethylene film on the other side of the polyester non-woven fabric, hot pressing at 100° C. for 6 seconds at a pressure of 0.5 MPa, and cooling to room temperature.

[0041] Example 3

[0042] A tear-resistant, moisture-resistant desiccant packaging material comprising a 25μm-thick polyester non-woven fabric, and polypropylene and polyethylene films adhered to either side of the polyester non-woven fabric. The polypropylene film is 25μm thick, and the polyethylene film is 15μm thick. The polyethylene film is made of linear low-density polyethylene.

[0043] The raw materials of the polyester non-woven fabric include: polyester fiber and prefabricated fiber with a diameter of 0.25 mm; the mass ratio of the polyester fiber to the prefabricated fiber is 40:35.

[0044] The polyester non-woven fabric was prepared by dispersing 180g of prefabricated fibers on a mesh curtain to form a bottom layer, evenly dispersing 400g of polyester fibers on the surface of the bottom layer to form a middle layer, dispersing 170g of prefabricated fibers on the surface layer, and hydroentanglement reinforcement.

[0045] The prefabricated fiber was prepared by the following specific operation: 200g of polyvinyl alcohol was added to 2500g of water, stirred at 73°C for 100min, the pH value of the system was adjusted to 8-9 with a 1.2mol / L sodium hydroxide solution, and kept warm for 25min. 200g of graphene oxide and 70g of epichlorohydrin were added thereto, stirred at 73°C for 100min, hydrochloric acid was used to adjust the system to neutral, freeze-dried, and melt-spun using a single-screw spinning equipment.

[0046] A method for producing tear-resistant and moisture-proof desiccant packaging material comprises the following steps: laminating a polypropylene film on one side of a polyester non-woven fabric, laminating a polyethylene film on the other side of the polyester non-woven fabric, hot pressing at 92° C. for 3 seconds at a pressure of 0.43 MPa, and cooling to room temperature.

[0047] Example 4

[0048] A tear-resistant, moisture-resistant desiccant packaging material comprising a 55μm-thick polyester non-woven fabric, and polypropylene and polyethylene films adhered to either side of the polyester non-woven fabric. The polypropylene film is 35μm thick, and the polyethylene film is 30μm thick. The polyethylene film is made of linear low-density polyethylene.

[0049] The raw materials of the polyester non-woven fabric include: polyester fiber and prefabricated fiber with a diameter of 0.25 mm; the mass ratio of the polyester fiber to the prefabricated fiber is 50:25.

[0050] The polyester non-woven fabric was prepared by dispersing 120 g of prefabricated fibers on a mesh curtain to form a bottom layer, evenly dispersing 500 g of polyester fibers on the surface of the bottom layer to form a middle layer, dispersing 130 g of prefabricated fibers on the surface layer, and hydroentanglement reinforcement.

[0051] The prefabricated fiber was prepared by the following specific operation: 120g of polyvinyl alcohol was added to 450g of water, stirred at a temperature of 77°C for 80min, a 1.8mol / L sodium hydroxide solution was used to adjust the pH value of the system to 8-9, and the mixture was kept warm for 15min. 120g of graphene oxide and 9g of epichlorohydrin were added thereto, stirred at a temperature of 77°C for 80min, hydrochloric acid was used to adjust the system to neutral, freeze-dried, and melt-spun using a single-screw spinning equipment.

[0052] A method for producing tear-resistant and moisture-proof desiccant packaging material comprises the following steps: laminating a polypropylene film on one side of a polyester non-woven fabric, laminating a polyethylene film on the other side of the polyester non-woven fabric, hot pressing at 98° C. for 5 seconds at a pressure of 0.47 MPa, and cooling to room temperature.

[0053] Example 5

[0054] A tear-resistant, moisture-resistant desiccant packaging material comprising a 40μm-thick polyester non-woven fabric, and polypropylene and polyethylene films adhered to either side of the polyester non-woven fabric. The polypropylene film is 25μm thick, and the polyethylene film is 32μm thick. The polyethylene film is made of linear low-density polyethylene.

[0055] The raw materials of the polyester non-woven fabric include: polyester fiber and prefabricated fiber with a diameter of 0.25 mm; the mass ratio of the polyester fiber to the prefabricated fiber is 45:30.

[0056] The polyester non-woven fabric is prepared by the following specific operations: 150g of prefabricated fibers are dispersed on a mesh curtain to form a bottom layer, 450g of polyester fibers are evenly dispersed on the surface of the bottom layer to form a middle layer, 150g of prefabricated fibers are dispersed on the surface layer, and hydroentangled for reinforcement.

[0057] The prefabricated fiber was prepared by the following specific operation: 150g of polyvinyl alcohol was added to 1000g of water, stirred at a temperature of 75°C for 90min, a 1.5mol / L sodium hydroxide solution was used to adjust the pH value of the system to 8-9, and the mixture was kept warm for 20min. 150g of graphene oxide and 25g of epichlorohydrin were added thereto, stirred at a temperature of 75°C for 90min, hydrochloric acid was used to adjust the system to neutral, freeze-dried, and melt-spun using a single-screw spinning equipment.

[0058] A method for producing tear-resistant and moisture-proof desiccant packaging material comprises the following steps: laminating a polypropylene film on one side of a polyester non-woven fabric, laminating a polyethylene film on the other side of the polyester non-woven fabric, hot pressing at 95° C. for 2 seconds at a pressure of 0.45 MPa, and cooling to room temperature.

[0059] Comparative Example 1

[0060] A tear-resistant, moisture-resistant desiccant packaging material comprising a 40μm-thick polyester non-woven fabric, and polypropylene and polyethylene films adhered to either side of the polyester non-woven fabric. The polypropylene film is 25μm thick, and the polyethylene film is 32μm thick. The polyethylene film is made of linear low-density polyethylene.

[0061] The raw materials of the polyester non-woven fabric include: polyester fiber and prefabricated fiber with a diameter of 0.25 mm; the mass ratio of the polyester fiber to the prefabricated fiber is 45:30.

[0062] The polyester non-woven fabric is prepared by the following specific operations: 150g of prefabricated fibers are dispersed on a mesh curtain to form a bottom layer, 450g of polyester fibers are evenly dispersed on the surface of the bottom layer to form a middle layer, 150g of prefabricated fibers are dispersed on the surface layer, and hydroentangled for reinforcement.

[0063] The prefabricated fiber was prepared by the following specific operation: 150g of polyvinyl alcohol was added to 1000g of water, stirred at 75°C for 90min, the pH value of the system was adjusted to 8-9 with a 1.5mol / L sodium hydroxide solution, and kept warm for 20min. 150g of nano-silica and 25g of epichlorohydrin were added thereto, stirred at 75°C for 90min, hydrochloric acid was used to adjust the system to neutral, freeze-dried, and melt-spun using a single-screw spinning equipment.

[0064] A method for producing tear-resistant and moisture-proof desiccant packaging material comprises the following steps: laminating a polypropylene film on one side of a polyester non-woven fabric, laminating a polyethylene film on the other side of the polyester non-woven fabric, hot pressing at 95° C. for 2 seconds at a pressure of 0.45 MPa, and cooling to room temperature.

[0065] Comparative Example 2

[0066] A tear-resistant, moisture-resistant desiccant packaging material comprising a 40μm-thick polyester non-woven fabric, and polypropylene and polyethylene films adhered to either side of the polyester non-woven fabric. The polypropylene film is 25μm thick, and the polyethylene film is 32μm thick. The polyethylene film is made of linear low-density polyethylene.

[0067] The polyester non-woven fabric is prepared by the following specific operation: 450g of polyester fibers are evenly dispersed on a mesh curtain of a mesh machine, and then reinforced by hydroentanglement.

[0068] A method for producing tear-resistant and moisture-proof desiccant packaging material comprises the following steps: laminating a polypropylene film on one side of a polyester non-woven fabric, laminating a polyethylene film on the other side of the polyester non-woven fabric, hot pressing at 95° C. for 2 seconds at a pressure of 0.45 MPa, and cooling to room temperature.

[0069] The puncture resistance of the packaging materials obtained in Example 5 and Comparative Examples 1-2 was measured with reference to GB / T 37841-2019 “Test method for puncture resistance of plastic films and sheets”.

[0070] The peel strength of the packaging materials obtained in Example 5 and Comparative Examples 1-2 was measured with reference to GB / T 8808-1988 “Peel test method for soft composite plastic materials”.

[0071] like Figure 1 As shown, the puncture resistance and peel strength of the packaging material obtained in Example 5 are the highest, which are better than those of Comparative Examples 1-2 (P < 0.05).

[0072] The longitudinal and transverse tear strengths of the packaging materials obtained in Example 5 and Comparative Examples 1-2 were measured with reference to QB / T 1130-1991 “Test method for right-angle tearing properties of plastics”.

[0073] like Figure 2 As shown, the longitudinal and transverse tearing strengths of the packaging material obtained in Example 5 are both the highest, which are better than those of Comparative Examples 1-2 (P < 0.05).

[0074] The packaging materials obtained in Example 5 and Comparative Examples 1-2 were completely immersed in deionized water for 24 hours, and then taken out to test their tear strength, and the tear strength retention rate was calculated.

[0075] With reference to GB / T 16422.3-2022 “Plastics Laboratory Light Source Exposure Test Methods Part 3: Fluorescent UV Lamp”, the packaging materials obtained in Example 5 and Comparative Examples 1-2 were subjected to UV aging treatment, and then their tear strength was tested, and the tear strength retention rate was calculated.

[0076] Tear strength retention rate = tear strength after treatment ÷ original tear strength × 100%

[0077] like Figure 3 As shown, the tear strength retention rate of the packaging material obtained in Example 5 after treatment is the highest, which is better than that of Comparative Examples 1-2 (P < 0.05).

[0078] The air permeability of the packaging materials obtained in Example 5 and Comparative Examples 1-2 was then tested according to ISO 5636 / 5; and the moisture permeability of the packaging materials obtained in Example 5 and Comparative Examples 1-2 was then tested according to Condition A in ASTM E96 / E96M.

[0079] like Figure 4 As shown, the air permeability of the packaging material obtained in Example 5 is the highest, which is better than that of Comparative Examples 1-2 (P<0.05), indicating that the air permeability of the packaging material obtained in Example 5 is the worst; and the moisture permeability of the packaging material obtained in Example 5 is the highest, which is better than that of Comparative Examples 1-2 (P<0.05), indicating that the moisture permeability of the packaging material obtained in Example 5 is the best; it is confirmed that the packaging material obtained in Example 5 is suitable for packaging desiccant.

[0080] The applicant believes that this is due to the fact that the present invention utilizes graphene oxide grafted onto polyvinyl alcohol, significantly enhancing the stability of the prefabricated fiber under the action of epichlorohydrin. Furthermore, the internal incorporation of a large amount of lamellar graphene results in the prefabricated fiber not only exhibiting excellent air and moisture permeability, but also maintaining excellent mechanical strength even after absorbing water. The present invention also utilizes polyester fibers laid in the center and prefabricated fibers laid on both sides to prepare a polyester nonwoven fabric. This results in excellent heat-pressing properties with polypropylene and polyethylene films, resulting in extremely strong bonding, high heat-sealing strength, and excellent tear resistance, even in humid environments. Furthermore, the fabric significantly enhances the packaging material's UV resistance, effectively preventing desiccant packaging from aging.

[0081] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A tear-resistant and moisture-proof desiccant packaging material, characterized in that: include: A polyester non-woven fabric, and a polypropylene film and a polyethylene film respectively attached to both sides of the polyester non-woven fabric; wherein the polypropylene film and the polyethylene film are both provided with through holes; The raw materials of polyester non-woven fabric include: polyester fiber and prefabricated fiber; the mass ratio of polyester fiber to prefabricated fiber is 30-60:20-40; The prefabricated fiber is prepared by the following specific operation: adding polyvinyl alcohol to water, stirring at 70-80°C for 1-2 hours, adjusting the pH value of the system to 8-9, keeping warm for 10-30 minutes, adding graphene oxide and epichlorohydrin, stirring at 70-80°C for 1-2 hours, adjusting the system to neutral, freeze drying, and melt spinning; Polyester non-woven fabric is made by the following specific operations: prefabricated fibers are dispersed on the mesh curtain of the mesh machine to form a bottom layer, polyester fibers are evenly dispersed on the surface of the bottom layer to form a middle layer, and then prefabricated fibers are dispersed on the surface of the middle layer to form a surface layer, and hydroentangled.

2. The tear-resistant and moisture-proof desiccant packaging material according to claim 1, characterized in that: The thickness of the polyester non-woven fabric is 20-60 μm, the thickness of the polypropylene film is 20-40 μm, and the thickness of the polyethylene film is 10-40 μm.

3. The tear-resistant and moisture-proof desiccant packaging material according to claim 1, characterized in that: The material used for polyethylene film is linear low-density polyethylene.

4. The tear-resistant and moisture-proof desiccant packaging material according to claim 1, characterized in that: The mass ratio of the prefabricated fibers used in the bottom layer to the prefabricated fibers used in the surface layer is 10-20:10-20.

5. The tear-resistant and moisture-proof desiccant packaging material according to claim 1, characterized in that: The diameter of the prefabricated fibers is 0.10-0.45 mm.

6. The tear-resistant and moisture-proof desiccant packaging material according to claim 1, characterized in that: The mass ratio of polyvinyl alcohol, graphene oxide and epichlorohydrin is 1-5:1-5:0.1-1.

7. The method for producing the tear-resistant and moisture-proof desiccant packaging material according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: sticking a polypropylene film on one side of a polyester non-woven fabric, sticking a polyethylene film on the other side of the polyester non-woven fabric, hot pressing, and cooling to room temperature.

8. The method for producing the tear-resistant and moisture-proof desiccant packaging material according to claim 7, characterized in that: The hot pressing temperature is 90-100°C, the hot pressing pressure is 0.4-0.5MPa, and the hot pressing time is 2-6s.

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