A hot pressing process for large-format thin plates

Abstract

The present application relates to the technical field of hot pressing, and particularly relates to a hot pressing process of large-format thin plate. The hot pressing process of large-format thin plate comprises the following hot pressing step: hot pressing by using a hot pressing device after laying a buffer pad under a plate; wherein, the upper and lower surfaces of the plate are sequentially provided with triamine paper and moisture-conducting release paper, and the heat-resistant temperature of the moisture-conducting release paper is greater than or equal to the hot pressing temperature. By setting the moisture-conducting release paper on the upper and lower surfaces of the plate, using the segmented pressing process of pre-pressing and then hot pressing, fast pressure relief and partition control technology, the moisture release effect of the plate is improved, the plate burst rate is significantly reduced, the production efficiency is improved, and the moisture-conducting release paper used in the method can be repeatedly used, and the material loss rate is low.

Description

Technical Field

[0001] This invention relates to the field of hot pressing technology, and more particularly to a hot pressing process for large-format thin plates. Background Technology

[0002] Existing hot-pressing processes are primarily suitable for small-sized sheets with a certain thickness. When directly hot-pressing large-format thin sheets (thickness ≤ 3mm), existing processes suffer from the following drawbacks: ① Due to the thinness of the sheet, moisture can only be released through the sides, resulting in insufficient diffusion paths and preventing complete moisture release in a short time; ② Traditional processes use only a single hot-pressing stage, failing to control the moisture release rate in stages; ③ Existing hot-press machines have excessively long depressurization times, affecting moisture release and resulting in low production efficiency. These issues make thin sheets highly susceptible to bursting due to internal steam pressure buildup during hot pressing, leading to high material loss. Summary of the Invention

[0003] The main objective of this invention is to provide a hot pressing process for large-format thin plates, aiming to improve the technical problems of poor moisture release and easy plate bursting in the existing hot pressing process for large-format thin plates.

[0004] To achieve the above objectives, the present invention proposes a hot pressing process for large-format thin plates, comprising the following hot pressing steps: after laying a buffer pad under the plate, hot pressing is performed using a hot pressing device; wherein, melamine paper and moisture-wicking release paper are sequentially arranged on both the upper and lower surfaces of the plate, and the heat resistance temperature of the moisture-wicking release paper is greater than or equal to the hot pressing temperature.

[0005] Preferably, the pressure during hot pressing is 14–15 MPa, the hot pressing temperature is 175–180 °C, and the hot pressing time is 15–22 s.

[0006] Preferably, the air permeability of the moisture-wicking release paper is ≥90mL / (cm²). 2 ·min)@4.88kPa, weight is 115-125g / m 2 .

[0007] Preferably, the air permeability of the moisture-wicking release paper gradually increases from its center to its edge;

[0008] The hot pressing pressure of the hot pressing equipment gradually decreases from the center to the edge.

[0009] Preferably, when the distance D between any position of the moisture-wicking release paper and the center is less than D1 mm, the air permeability T of the moisture-wicking release paper is T = a × D + 90, where the value of a is in the range of 0.022 ≤ a ≤ 0.028.

[0010] When the distance D between any position and the center of the moisture-wicking release paper is greater than or equal to D1 mm, the air permeability of the moisture-wicking release paper is T = b × D - 5, where the value of b is in the range of 0.18 ≤ b ≤ 0.22.

[0011] Where D1 is the preset threshold.

[0012] Preferably, the plate is pre-pressed before the hot pressing step. The pre-pressing step is as follows: after laying a buffer pad on the lower layer of the plate, the pre-pressing pressure is 12.9-13.1 MPa, the pre-pressing temperature is 178-182℃, and the pre-pressing time is 10s.

[0013] Preferably, the depressurization time of the hot pressing equipment after hot pressing or pre-pressing is controlled to be ≤1s.

[0014] Preferably, the moisture content of the sheet material before hot pressing or pre-pressing is 6-8%.

[0015] Preferably, the sheet material is polished before hot pressing or pre-pressing to achieve a surface roughness Ra ≤ 0.8 μm and a flatness ≤ 0.5 mm / m. 2 .

[0016] Preferably, the buffer pad is particleboard.

[0017] Compared with the prior art, the hot pressing process for large-format thin plates of the present invention has the following advantages:

[0018] 1. Set up multi-dimensional moisture release channels: During hot pressing, moisture-wicking release paper is set on the top and bottom surfaces of the board, so that the board can release moisture simultaneously from the "surface + side".

[0019] 2. Segmented pressing process: The board is first pre-pressed, and then the board is subjected to main pressing (hot pressing) to control the moisture release rate in a coordinated manner;

[0020] 3. Rapid depressurization: The depressurization time during hot pressing or pre-pressurization is controlled to be ≤1s by using hot pressing equipment to avoid steam back absorption caused by depressurization delay;

[0021] 4. Zoning control technology: Based on the difference in moisture distribution between the edge and center areas of the board, the air permeability of the moisture-wicking release paper and the pressure gradient during hot pressing are dynamically adjusted.

[0022] By employing the aforementioned multi-dimensional moisture release channels, segmented pressing process, rapid pressure relief, and zoned control technology, the moisture release effect of the board is improved, significantly reducing the board bursting rate and increasing production efficiency. Furthermore, the moisture-wicking release paper used in this method can be reused multiple times, resulting in low material loss. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the sheet material in this scheme during pre-pressing;

[0025] Figure 2 This is a schematic diagram of the sheet material in this scheme during hot pressing.

[0026] In the attached diagram: 1-board, 2-buffer pad, 3-melamine paper, 4-moisture-wicking release paper, 5-pressure plate.

[0027] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Furthermore, the technical solutions of the various embodiments can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0030] A hot-pressing process for a large-format thin sheet includes the following hot-pressing steps: after laying a buffer pad 2 under the sheet 1, hot pressing is performed using a hot-pressing device; wherein, melamine paper 3 and moisture-wicking release paper 4 are sequentially arranged on both the upper and lower surfaces of the sheet 1, and the heat resistance temperature of the moisture-wicking release paper 4 is greater than or equal to the hot-pressing temperature (in this arrangement, the upper pressure plate 5 of the hot-pressing device acts on the moisture-wicking release paper 4 on the upper surface of the sheet 1, and the upper pressure plate 5 of the hot-pressing device acts on the lower surface of the buffer pad 2).

[0031] The hot-pressing process of this solution is particularly suitable for pressing large-format sheet materials 1 with a thickness ≤3mm (e.g., 49-foot sheet materials with a length of 2800mm and a width of 1220mm). When the thickness of sheet material 1 is greater than 3mm, due to the material's strong moisture storage capacity and long moisture diffusion path, conventional hot-pressing processes can meet production requirements. Of course, the hot-pressing process of this solution can also be used (e.g., segmented pressing, rapid pressure release), with adjustments made according to the characteristics of sheet material 1. However, for thin sheets (sheet material 1) with a thickness of less than 3mm, due to their light weight and thinness, traditional hot-pressing processes are prone to causing sheet bursting. This is mainly because the release channels of internal moisture are severely restricted during hot pressing, and the internal pressure that thin sheets can withstand is relatively low. Therefore, the special hot-pressing process of this invention is required.

[0032] Specifically, this is achieved by laying melamine paper 3 and moisture-wicking release paper 4 on both the top and bottom surfaces of the board 1 (in this solution, moisture-wicking release paper 4 refers to release paper with numerous micropores on the entire surface, providing a certain degree of moisture wicking). The melamine paper 3 serves a protective and decorative function; the moisture-wicking release paper 4, in addition to its traditional isolation function, also has a special moisture-wicking function, allowing the board 1 to release moisture in a directional manner through the micropores of the moisture-wicking release paper 4. Besides the traditional side release, moisture can also be released from both the top and bottom surfaces of the board 1 through the moisture-wicking release paper 4, reducing the risk of board bursting during hot pressing. During hot pressing, a buffer pad 2 is also laid under the board 1. The buffer pad 2 has a certain buffering effect, ensuring that the pressure is evenly distributed across the entire surface of the board 1, improving the basic performance of the board 1, and also reducing the risk of board bursting to some extent. Since the buffer pad 2 has already received and stored high temperatures during the pre-pressing stage, the lower surface of the board 1 and the moisture-wicking release paper 4 can still release moisture under high temperatures during the hot pressing process.

[0033] Typically, to maintain the normal function of the moisture-wicking release paper 4, its heat resistance temperature needs to be higher than the preheating or hot-pressing temperature of this solution. Generally, the dimensions of the board 1 and the cushioning pad 2 are the same, but the dimensions of the melamine paper 3 and the moisture-wicking release paper 4 are slightly larger than the dimensions of the board 1, with a specification of 2820mm*1250mm. After pressing, the moisture-wicking release paper 4 is peeled off and recycled, and the excess portion of the melamine paper 3 is scraped off.

[0034] Furthermore, the hot-pressing pressure is 14–15 MPa, the hot-pressing temperature is 175–180℃, and the hot-pressing time is 15–22 s. The hot-pressing process of this scheme can adopt the above hot-pressing parameters. The optimal hot-pressing pressure is 15 ± 0.1 MPa, the temperature is 180℃, and the time is 20 s.

[0035] Furthermore, the air permeability of the moisture-wicking release paper 4 is ≥90mL / (cm). 2·min)@4.88kPa, weight is 115-125g / m 2 The air permeability of the moisture-wicking release paper 4 in this solution is controlled within the above-mentioned range. This setting fully considers that: excessively high air permeability will lead to rapid moisture release, causing blistering on the surface of board 1; excessively low air permeability will fail to meet the requirements for rapid moisture wicking; and an air permeability of 90 mL / (cm²) is considered optimal. 2 When the air permeability is above 4.88 kPa (referring to the volume of gas passing through the moisture-wicking release paper 4 per unit area per unit time under a pressure difference of 4.88 kPa, the unit of air permeability is determined with reference to the ASTM D737 standard to determine the complete unit system), it can ensure the effective release of moisture without affecting the surface quality of the product.

[0036] As for the moisture-wicking release paper 4, the required basis weight is 115-125 g / m². 2 Within this range, the determination of this parameter is mainly based on the following reasons: when the weight is less than 115g / m³ 2 At that time, the strength of the moisture-wicking release paper 4 is insufficient, and it is easily damaged during the pressing process; when the basis weight is greater than 125g / m², the release paper is also prone to breakage. 2 At this time, although the strength increases, it will affect the water conduction efficiency; 115-125g / m 2 The weight allows for an optimal balance between strength and breathability.

[0037] Furthermore, the air permeability of the moisture-wicking release paper 4 gradually increases from its center to its edge; conversely, the hot-pressing pressure of the hot-pressing equipment gradually decreases from its center to its edge. In this design, the pressure difference between the center and edge of the hot-pressing equipment is achieved through multi-zone pressure control. Typically, the pressure at the center is higher than at the edge, with a gradually decreasing pressure trend; that is, the center pressure is higher and the edge pressure is lower. This design helps to drive moisture from the high-pressure center area to the low-pressure edge area, thereby achieving efficient moisture wicking and further reducing the risk of board bursting due to internal stress.

[0038] The hot pressing equipment in this solution also sets pressure gradients for different positions of the plate 1. From the center to the edge, the hot pressing pressure of the hot pressing equipment gradually decreases. Specifically, this is achieved through zoned control via a hydraulic system. The hydraulic system of the hot pressing equipment is divided into multiple independent control zones (such as the center zone and the edge zone). The pressure of each zone can be dynamically adjusted by an independent hydraulic cylinder or servo valve.

[0039] Furthermore, when the distance D between any position of the moisture-wicking release paper 4 and the center is less than D1 mm, the air permeability T of the moisture-wicking release paper 4 is T = a × D + 90, and the value of a is in the range of 0.022 ≤ a ≤ 0.028 (preferably 0.025).

[0040] When the distance D between any position and the center of the moisture-wicking release paper 4 is greater than or equal to D1 mm, the air permeability of the moisture-wicking release paper 4 is T = b × D - 5, and the value of b is in the range of 0.18 ≤ b ≤ 0.22 (preferably 0.2).

[0041] Wherein, D1 is a preset threshold, which can be 550mm.

[0042] In this embodiment, the width / size of the moisture-wicking release paper 4 is usually consistent with the width / size of the board 1. The air permeability change of the moisture-wicking release paper 4 typically includes the two stages mentioned above. When the distance D between a certain position of the moisture-wicking release paper 4 and its center is less than 550mm, the air permeability is obtained using the formula T = 0.025 × D + 90. When the distance D between a certain position of the moisture-wicking release paper 4 and its center is greater than or equal to 550mm, the position is closer to the edge, and the air permeability is obtained using the formula T = 0.2 × D - 5. This further reduces the risk of board bursting in thinner boards 1. When D is in mm, the calculated air permeability T is in mL / (cm²). 2 ·min)@4.88kPa; When D uses other units, the conversion calculation can be performed.

[0043] The optimal parameters are as follows: when the distance D between any position and the center of the moisture-wicking release paper 4 is less than 550 mm, the air permeability T of the moisture-wicking release paper 4 is 0.025 × D + 90; when the distance D between any position and the center of the moisture-wicking release paper 4 is greater than or equal to 550 mm, the air permeability T of the moisture-wicking release paper 4 is 0.2 × D - 5. For example, in actual production, the width of the moisture-wicking release paper 4 is 1250 mm, and the air permeability T at the center position is 0.025 × 0 + 90 = 90 mL / (cm²). 2 ·min)@4.88kPa; when 200mm from the center, the air permeability T is 0.025×200+90=95mL / (cm³). 2 ·min)@4.88kPa; when 600mm from the center, the air permeability T is 0.2×600-5=115mL / (cm) 2 At a pressure of 4.88 kPa, the air permeability T at the outermost edge (625 mm from the center) is 0.2 × 625 - 5 = 120 mL / (cm³). 2 ·min)@4.88kPa.

[0044] Moisture-wicking release papers with the aforementioned variation patterns are already available on the market. These products generally achieve moisture release through structural design or material modification. Regarding physical structural design: for example, breathable kitchen release papers employ a multi-layered composite structure, including a base paper layer, a coating layer, a release agent layer, and a dust-removing layer. Each layer has evenly distributed ventilation holes in the vertical direction, with the ventilation holes in adjacent layers staggered. This design allows moisture to escape through the pores while maintaining release properties, making it suitable for lamination processes where humidity is a concern. Furthermore, hydrophilic materials or moisture-absorbing layers can be coated to alter the moisture-wicking capacity of different areas. Some release papers also incorporate hydrophilic resins in the adhesive layer, softening the material during high-temperature lamination, filling gaps, and guiding moisture out.

[0045] Furthermore, the plate 1 is pre-pressed before the hot pressing step. The pre-pressing step is as follows: after laying the buffer pad 2 on the lower layer of the plate 1, the pre-pressing pressure is 12.9-13.1 MPa, the pre-pressing temperature is 178-182℃, and the pre-pressing time is 10s.

[0046] In this embodiment, a pre-pressing stage is added before hot pressing, employing a segmented pressing process combining pre-pressing and main pressing. Specifically, a 2000t hot pressing device is selected. The board 1 and the buffer pad 2 (such as particleboard) are placed together into the hot pressing device. The hot pressing device is started, with parameters set to pressure 12.9–13.1 MPa, temperature 178–182°C, and time 10s. Through the buffering effect of the buffer pad 2, the pressure distribution and heat conduction efficiency are optimized, initially compacting the board 1 and activating the moisture-wicking function of the moisture-wicking release paper 4. After the pre-pressing step is completed, the board 1 and the buffer pad 2 are removed for subsequent hot pressing processes.

[0047] In the pre-pressing process of the present invention, the heating rate during the pre-pressing process can be precisely controlled at 11±0.5℃ / s. At this heating rate, the internal moisture diffusion rate and the surface evaporation rate of the material reach the best balance, and the movement energy of water molecules is moderate. This will not cause violent evaporation and avoid thermal stress cracking caused by excessive temperature difference between the inside and outside of the material; at the same time, it can maintain a continuous release rate and maintain high production efficiency.

[0048] Furthermore, the depressurization time of the hot pressing equipment after hot pressing or pre-pressing is controlled to be ≤1s. In this embodiment, the hot pressing equipment utilizes an accumulator to achieve rapid depressurization, thereby solving the problem of easy board bursting caused by excessively long depressurization time during the pressing process of the board 1 in the prior art. When the accumulator of the hot pressing equipment depresses, the pressure plate 5 of the hot pressing equipment is lifted through the accumulator to quickly release the pressure, wherein the depressurization time is ≤1s. The pressure sensor (accuracy class 0.2) in the equipment detects the pressure at the four corners and center of the pressure plate in real time, and automatically adjusts if the fluctuation exceeds the limit. After hot pressing is completed, the pressed finished board is taken out. The single hot pressing cycle is shortened by about 10%, realizing efficient production.

[0049] Furthermore, the moisture content of the sheet material 1 before hot pressing or pre-pressing is 6-8%. In this embodiment, the initial moisture content of the sheet material 1 is controlled within the range of 6%-8%. This range is set with full consideration of the following factors: if the moisture content of the sheet material 1 is below 6%, it will become too dry and prone to cracking; if the moisture content is above 8%, even if the above steps are taken, excessive moisture may cause bubbles or delamination during the pressing process; a moisture content range of 6%-8% can ensure that the sheet material 1 has sufficient plasticity, while not affecting the pressing quality due to excessive moisture.

[0050] In actual production, board 1 is placed in a constant temperature and humidity room (temperature 23±2℃, humidity 55±5%), and an infrared moisture meter is used to measure multiple points. Samples with excessive moisture content are removed, and the initial moisture content is controlled to be 6%-8%.

[0051] Furthermore, the sheet material 1 is polished before hot pressing or pre-pressing to ensure that its surface roughness Ra ≤ 0.8 μm and flatness ≤ 0.5 mm / m. 2 .

[0052] Good flatness of sheet material 1 ensures a good pressing effect in the subsequent process. In this embodiment, a sander (with a grit size of 240#) is used to polish the surface of sheet material 1, so that the surface roughness Ra of sheet material 1 is ≤0.8μm and the flatness is ≤0.5mm / m. 2 This helps ensure that the surface of the sheet 1 is subjected to uniform stress during the pressing process.

[0053] Furthermore, the buffer pad 2 is made of particleboard. In actual production, particleboard can be used as the buffer pad 2. The thickness of particleboard is usually around 18mm, which is a suitable thickness to evenly distribute the pressure during pre-pressing / hot pressing and prevent the board 1 from deforming or being damaged due to excessive local pressure.

[0054] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0055] In the following blank examples and various embodiments, the dimensions of the board 1 used for hot pressing are 2800mm * 1220mm, and the thickness is 3mm; the cushioning pad 2 is 18mm thick particleboard; and the melamine paper 3 has a basis weight of 185g / m². 2 .

[0056] Blank example 1

[0057] The sheet material 1 was directly hot-pressed using a hot-pressing device, which was not equipped with an accumulator for normal pressure release. The hot-pressing pressure was 15 MPa, the hot-pressing temperature was 180℃, the hot-pressing time was 22 s, and the pressure release time was 3 s.

[0058] Blank example 2

[0059] The sheet material 1 is directly hot-pressed using a hot-pressing device equipped with an accumulator for rapid pressure release. The hot-pressing pressure is 15 MPa, the hot-pressing temperature is 180℃, the hot-pressing time is 22 s, and the pressure release time is 1 s.

[0060] Example 1

[0061] A hot-pressing process for a large-format thin sheet includes the following hot-pressing steps: melamine paper 3 and moisture-wicking release paper 4 are sequentially placed on both the upper and lower surfaces of the sheet 1. A buffer pad 2 is then laid underneath the sheet 1. Hot pressing is performed using a hot-pressing device equipped with an accumulator for rapid pressure release. The hot-pressing pressure is 15 MPa, the hot-pressing temperature is 180℃, the hot-pressing time is 22 s, and the pressure release time is 1 s. The air permeability of the moisture-wicking release paper 4 at each location is 90 mL / (cm²). 2 ·min)@4.88kPa, weight is 115g / m 2 .

[0062] Example 2

[0063] A hot-pressing process for a large-format thin sheet includes the following hot-pressing steps: melamine paper 3 and moisture-wicking release paper 4 are sequentially placed on both the upper and lower surfaces of the sheet 1. A buffer pad 2 is then laid underneath the sheet 1. Hot pressing is performed using a hot-pressing device equipped with an accumulator for rapid pressure release. The hot-pressing pressure is 14 MPa, the hot-pressing temperature is 175℃, the hot-pressing time is 15 s, and the pressure release time is 1 s. The air permeability of the moisture-wicking release paper 4 at each location is 110 mL / (cm²). 2 ·min)@4.88kPa, weight is 120g / m 2 .

[0064] Example 3

[0065] A hot-pressing process for a large-format thin sheet includes the following hot-pressing steps: melamine paper 3 and moisture-wicking release paper 4 are sequentially placed on both the upper and lower surfaces of the sheet 1. A buffer pad 2 is then laid underneath the sheet 1. Hot pressing is performed using a hot-pressing device equipped with an accumulator for rapid pressure release. The hot-pressing pressure is 14 MPa, the hot-pressing temperature is 175℃, the hot-pressing time is 15 s, and the pressure release time is 1 s. The air permeability of the moisture-wicking release paper 4 is 100 mL / (cm³). 2 ·min)@4.88kPa, weight is 125g / m 2 .

[0066] Record the bursting phenomenon and moisture content of the finished boards of blank examples 1-2 and examples 1-3 after hot pressing. The specific test results are shown in the table below:

[0067]

[0068]

[0069] Note: 1. Use 100 boards to perform the hot pressing steps of the blank example and Examples 1 to 3 respectively, observe whether cracks appear in the finished boards after hot pressing, and record the number of products with cracks; board bursting rate (%) = (number of finished boards with cracks / total number of finished boards) × 100%.

[0070] 2. Moisture-wicking efficiency (%) = 1 - ((initial moisture content of the board - moisture content of the board after hot pressing) / initial moisture content of the board) × 100%, where the moisture content is directly measured by a moisture content meter and is the average value of the entire board surface.

[0071] The test results of blank example 1 and blank example 2 show that the rapid depressurization method can reduce the plate burst rate to a certain extent and improve the moisture wicking efficiency to a certain extent.

[0072] The test results from Example 1 and Blank Example 2 show that the bursting rate is high when the thin sheet 1 is directly hot-pressed. However, by placing a moisture-wicking release paper 4 (melamine paper 3) on the sheet 1 and placing a buffer pad 2 under the sheet 1 before hot-pressing, the bursting rate can be reduced to 20%. Furthermore, according to the test results of Examples 1-3 of this scheme, even when hot-pressing thin sheet 1, the bursting rate can be reduced to below 20% using the hot-pressing process of this scheme, significantly reducing the bursting of sheet 1 (thin sheet), improving moisture wicking efficiency, and resulting in a higher yield of qualified sheet 1.

[0073] Example 4

[0074] In this embodiment, all hot-pressing steps and parameters are the same as in Example 1. The difference lies in the air permeability of the moisture-wicking release paper 4. Specifically, when the distance between the center and the left and right sides of the moisture-wicking release paper 4 is <200mm, the air permeability of the moisture-wicking release paper 4 is 90mL / (cm). 2 When the distance between the center and the left and right sides of the moisture-wicking release paper 4 is less than 400mm and the pressure is 200mm, the air permeability of the moisture-wicking release paper 4 is 100mL / (cm). 2 When the distance between the center and the left and right sides of the moisture-wicking release paper 4 is less than 600mm and the pressure is 400mm, the air permeability of the moisture-wicking release paper 4 is 110mL / (cm). 2When the distance between the center and the left and right sides of the moisture-wicking release paper 4 is ≤625mm and the pressure is ≤600mm, the air permeability of the moisture-wicking release paper 4 is 120mL / (cm). 2 ·min)@4.88kPa.

[0075] The cracking and moisture content of the finished board after hot pressing in Example 4 were recorded. The specific test results are shown in the table below:

[0076] Breakage rate / % Moisture wicking efficiency / % Example 4 10 80

[0077] As shown in the test results of Example 4 in the table above, the air permeability of the moisture-wicking release paper 4 in Example 1 is uniform, while the air permeability of the moisture-wicking release paper 4 in Example 4 increases relatively uniformly from the center to the edge (an increase of 10 mL / (cm²) per 200 mm). 2 With a pressure of 4.88 kPa (min), the rate of board breakage of board 1 is reduced to about 10%, while the moisture-wicking efficiency is improved.

[0078] Example 5

[0079] In this embodiment, all hot-pressing steps and parameters are the same as in Example 4. The difference lies in the air permeability of the moisture-wicking release paper 4. Specifically, the air permeability at the center of the moisture-wicking release paper 4 is 90 mL / (cm). 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 100mm, the air permeability T=0.025×100+90=92.5mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 200mm, the air permeability T=0.025×200+90=95mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 300mm, the air permeability T=0.025×300+90=97.5mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 400mm, the air permeability T=0.025×400+90=100mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 500mm, the air permeability T=0.025×500+90=102.5mL / (cm 2 ·min)@4.88kPa;

[0080] When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 550 mm, the air permeability T = 0.2 × 550 - 5 = 105 mL / (cm²) 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 600mm, the air permeability T=0.2×600-5=115mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 625mm, the air permeability T=0.2×625-5=120mL / (cm 2 ·min)@4.88kPa.

[0081] The cracking and moisture content of the finished board after hot pressing in Example 5 were recorded. The specific test results are shown in the table below:

[0082] Breakage rate / % Moisture wicking efficiency / % Example 5 8 81

[0083] As can be seen from the test results of Example 5 in the table above, the air permeability of the moisture-wicking release paper 4 in Example 5 is adjusted using the special calculation method in this scheme, which further reduces the bursting rate of board 1, specifically to about 8%, while the moisture wicking efficiency is improved.

[0084] Example 6

[0085] In this embodiment, all hot pressing steps and parameters are the same as in embodiment 5. The difference is that a pre-pressing process is added. Specifically, the board 1 is pre-pressed before hot pressing. The pre-pressing process is as follows: after laying a buffer pad 2 on the lower layer of the board 1, pre-pressing is performed. The pressure during pre-pressing is 13MPa, the pre-pressing temperature is 180℃ (the temperature received by the board 1 from the buffer pad 2, melamine paper 3 and moisture-wicking release paper 4 is about 110℃), and the pre-pressing time is 10s.

[0086] The cracking and moisture content of the finished board after hot pressing in Example 6 were recorded. The specific test results are shown in the table below:

[0087] Breakage rate / % Moisture wicking efficiency / % Example 6 7 83

[0088] As can be seen from the test results of Example 6 in the table above, after adding the pre-pressing step, the segmented pressing method can better facilitate the discharge of moisture from the board 1, reduce the board bursting rate to 7%, and achieve a moisture-wicking efficiency of about 83%.

[0089] Example 7

[0090] A hot pressing process for large-format thin plates includes the following hot pressing steps:

[0091] After laying the buffer pad 2 under the board 1, pre-compression is carried out. The pressure during pre-compression is 13MPa, the pre-compression temperature is 180℃, and the pre-compression time is 10s.

[0092] Triamine paper 3 and moisture-wicking release paper 4 are sequentially placed on both the top and bottom surfaces of the board 1. After a buffer pad 2 is laid under the board 1, hot pressing is performed using a hot pressing device.

[0093] The hot-pressing pressure is 15 MPa, the hot-pressing temperature is 180℃, the hot-pressing time is 20 s, and the pressure release time is 1 s; the basis weight of the moisture-wicking release paper 4 is 120 g / m². 2 The air permeability at the center of the moisture-wicking release paper 4 is 90 mL / (cm). 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 100mm, the air permeability T=0.025×100+90=92.5mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 200mm, the air permeability T=0.025×200+90=95mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 300mm, the air permeability T=0.025×300+90=97.5mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 400mm, the air permeability T=0.025×400+90=100mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 500mm, the air permeability T=0.025×500+90=102.5mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 550mm, the air permeability T=0.2×550-5=105mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 600mm, the air permeability T=0.2×600-5=115mL / (cm 2 ·min)@4.88kPa; When the distance between the center and the left and right sides of the moisture-wicking release paper 4 increases to 625mm, the air permeability T=0.2×625-5=120mL / (cm 2 ·min)@4.88kPa.

[0094] The table below records the board bursting issue of the finished board from Example 9 after hot pressing.

[0095] Breakage rate / % Moisture wicking efficiency / % Example 9 4 85

[0096] As can be seen from the test results of Example 9 in the table above, when the parameters of the moisture-wicking release paper 4, the pre-pressing parameters, the hot-pressing parameters and the pressure relief time are optimized at the same time, the bursting rate of the finished board of this scheme can be reduced to about 4-5%, and the moisture wicking efficiency can be increased to about 85%.

[0097] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A hot pressing process of a large-format thin sheet, characterized by, The hot pressing process includes the following steps: after laying a buffer pad (2) under the sheet (1), hot pressing is performed using a hot pressing device; The upper and lower surfaces of the board (1) are respectively provided with melamine paper (3) and moisture-wicking release paper (4), and the heat resistance temperature of the moisture-wicking release paper (4) is greater than or equal to the hot pressing temperature. From the center to the edge of the moisture-wicking release paper (4), the air permeability of the moisture-wicking release paper (4) gradually increases; The hot pressing pressure of the hot pressing equipment gradually decreases from the center to the edge.

2. The hot pressing process of a large-format thin plate according to claim 1, characterized in that, The pressure during hot pressing is 14–15 MPa, the hot pressing temperature is 175–180℃, and the hot pressing time is 15–22 seconds.

3. The process according to claim 1, wherein The moisture-conducting release paper (4) has a gas permeability of ≥ 90 mL / (cm 2 ·min) and a grammage of 115-125 g / m 2 .

4. The process according to claim 1, wherein When the distance D between any position and the center of the moisture-wicking release paper (4) is less than D1 mm, the air permeability of the moisture-wicking release paper (4) is T = a × D + 90, where the value of a is 0.022 ≤ a ≤ 0.

028. When the distance between any position and the center of the moisture-wicking release paper (4) is D≥D1 mm, the air permeability of the moisture-wicking release paper (4) is T=b×D-5, and the value of b is 0.18≤b≤0.22; Where D1 is the preset threshold.

5. The process according to claim 1, wherein Before the hot pressing step, the plate (1) is pre-pressed. The pre-pressing step is as follows: after laying a buffer pad (2) on the lower layer of the plate (1), the pre-pressing is carried out. The pressure during pre-pressing is 12.9 to 13.1 MPa, the pre-pressing temperature is 178 to 182℃, and the pre-pressing time is 10s.

6. The process according to claim 5, wherein The depressurization time of the hot pressing equipment after hot pressing or pre-pressing is controlled to be ≤1s.

7. The process according to claim 5, wherein The moisture content of the board (1) before hot pressing or pre-pressing is 6-8%.

8. The process according to claim 5, wherein The board (1) is polished before hot pressing or pre-pressing, so that the surface roughness Ra of the board (1) is ≤0.8 μm and the flatness is ≤0.5 mm / m 2 .

9. The process of claim 1, wherein, The buffer pad (2) is made of particleboard.

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