Anti-curling process for ultra-thin fiberboard with melamine impregnated film paper facing

Abstract

The present invention discloses a process for preventing curling of ultra-thin fiberboard with melamine impregnated film paper facing, and belongs to the field of fiberboard research and development. The process for preventing curling of ultra-thin fiberboard with melamine impregnated film paper facing comprises the following steps: (1) placing the ultra-thin fiberboard with melamine impregnated film paper facing on an improved cushion layer and performing hot pressing; (2) placing the ultra-thin fiberboard with melamine impregnated film paper facing on an anti-curling workbench with the paper surface on top and applying continuous pressure; (3) placing the ultra-thin fiberboard on a pallet and performing water spraying treatment; (4) placing the ultra-thin fiberboard with melamine impregnated film paper facing under pressure; (5) packaging the ultra-thin fiberboard with melamine impregnated film paper facing under pressure, and finally obtaining the anti-curling ultra-thin fiberboard with melamine impregnated film paper facing. The present invention reduces the curling degree of the ultra-thin fiberboard with melamine impregnated film paper facing by improving the process and equipment, and the prepared ultra-thin fiberboard with melamine impregnated film paper facing is flat, which reduces the difficulty of re-pasting, saves labor, and improves production efficiency.

Description

Technical Field

[0001] The invention relates to an anti-curling process for ultra-thin fiberboard with melamine impregnated adhesive film paper facing, and belongs to the field of fiberboard research and development. Background Art

[0002] The application of melamine-impregnated paper-faced ultra-thin fiberboard (thickness ≤1.5 mm) on wood-based panel substrates is restricted by the serious curling problem. The main causes of curling include the following aspects: First, in terms of structure, melamine-impregnated paper-faced ultra-thin fiberboard is composed of one side with paper and the other side without paper, and has an asymmetric structure. Since the density of melamine-impregnated paper is greater than that of ultra-thin fiberboard, and the surface density of the paper is greater than that of the unpapered surface, this structure leads to different densities on both sides of the material; secondly, in terms of components, melamine-impregnated paper is composed of melamine resin-impregnated paper-based material, while ultra-thin fiberboard is composed of wood fibers bonded with adhesives. Their viscoelastic properties are different, resulting in different thermal stresses and volume stresses generated during hot pressing. The viscoelasticity of the ultra-thin fiberboard is greater than that of the melamine-impregnated paper. Therefore, after hot pressing, the unpasted side rebounds toward the pasted side, resulting in curling and deformation. Finally, in the hot pressing process, one side of the hot pressing plate is heated while the other side is not. The side with the melamine-impregnated paper is subjected to high-temperature hot pressing treatment, and the thermal stress and volume stress generated are higher than those of the unheated side, further increasing the asymmetric stress and making the curling of the fiberboard more serious.

[0003] The curling problem of ultra-thin fiberboard with melamine impregnated paper veneer not only requires at least four workers to complete the subsequent re-pasting process, which increases labor costs and seriously affects production efficiency; in addition, the ultra-thin fiberboard with melamine impregnated paper veneer is too curled during the re-pasting process, which can easily damage the board surface and cause surface cracks, leading to quality problems. What's worse, fiberboards with too much curling cannot even be used, resulting in an increase in the scrap rate and further increasing production costs. Therefore, it is particularly important to reduce the curling degree of ultra-thin fiberboard with melamine impregnated paper veneer during the re-pasting process. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an anti-curling process for an ultra-thin fiberboard with a melamine impregnated film paper facing, which can reduce the curling degree of the ultra-thin fiberboard with a melamine impregnated film paper facing. The prepared ultra-thin fiberboard with a melamine impregnated film paper facing is flat, ensuring that the impregnated paper can be pressed intact on the ultra-thin fiberboard with a melamine impregnated film paper facing, reducing the difficulty of re-pasting, saving labor, reducing production costs, and improving economic benefits.

[0005] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows:

[0006] A process for preventing curling of ultra-thin fiberboard with melamine impregnated adhesive film paper facing comprises the following steps:

[0007] (1) placing the melamine impregnated adhesive film paper facing ultra-thin fiberboard on the improved cushion layer, and performing hot pressing at a surface pressure of 8-12 MPa to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 1;

[0008] (2) placing the melamine impregnated adhesive film paper facing ultra-thin fiberboard 1 on an anti-curling workbench with the adhesive paper facing upward, applying a pressure of 450-550 Pa for 25-35 seconds, and obtaining the melamine impregnated adhesive film facing ultra-thin fiberboard 2;

[0009] (3) placing the melamine impregnated film-faced ultra-thin fiberboard 2 on a pallet and spraying it with water to obtain the melamine impregnated film-faced ultra-thin fiberboard 3;

[0010] (4) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 3 under pressure for 20-36 hours to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 4;

[0011] (5) The melamine impregnated film facing ultra-thin fiberboard 4 is packaged and placed under heavy pressure for 2-4 days to obtain an anti-curling melamine impregnated film facing ultra-thin fiberboard.

[0012] After the ultra-thin fiberboard is pasted with melamine impregnated paper, the cross-sectional density of the melamine impregnated paper is different from that of the fiberboard, so the ultra-thin fiberboard after pressing will curl. It is worth noting that wood has viscoelasticity. The higher the temperature, the denser the board is pressed. However, after being subjected to high temperature and high pressure, the board will have resilience, and the thermal stress and volume stress will change, resulting in curling. The thinner the fiberboard, the greater the degree of curling. The present invention reduces the volume stress and thermal stress of the ultra-thin fiberboard with melamine impregnated film paper veneer by improving the pressing process, improves the heterogeneity of the ultra-thin fiberboard with melamine impregnated film paper veneer, and thus reduces the degree of curling of the ultra-thin fiberboard with melamine impregnated film paper veneer.

[0013] Furthermore, the bending coefficient of the anti-curling melamine impregnated film facing ultra-thin fiberboard is less than 5*10 -3 .

[0014] Furthermore, the bending coefficient of the anti-curling melamine impregnated film facing ultra-thin fiberboard is measured by setting the equation y=ax 2-h simulates the bending shape of the fiberboard. In an environment with a temperature of 25℃ and a humidity of 30%rh, a fiberboard with a size of 600 mm*600 mm is bent upward. The distance from the ground to the highest point of the fiberboard curling is measured, recorded as h, and the distance between the boards at the highest point of the fiberboard bending is measured, recorded as l. According to the above equation, the value a obtained is the bending coefficient obtained by determining the bending degree of the board. The larger a is, the greater the bending degree is, and vice versa, the smaller the bending degree is.

[0015] The evaluation criteria for fiberboard are shown in Table 1:

[0016] Table 1. Evaluation criteria for anti-curling melamine-impregnated film-faced ultra-thin fiberboard

[0017] Furthermore, in step (1), the thickness of the melamine impregnated adhesive film paper facing ultra-thin fiberboard is ≤1.5 mm.

[0018] Furthermore, in step (1), the hot pressing time is 8-16s, and the hot pressing temperature is 195-215°C.

[0019] Furthermore, in step (1), the hot pressing time is 10-14s, and the hot pressing temperature is 200-210°C. After the melamine impregnated paper is pressed, the thermal stress and volume stress of the ultra-thin fiberboard with melamine impregnated film paper are increased because one side is subjected to high temperature treatment, and the other side is not subjected to high temperature treatment, thereby increasing the effect of asymmetric stress of the ultra-thin fiberboard with melamine impregnated film paper. However, wood is a non-insulator. As the temperature and time increase, the temperature of the board increases, the difference between the volume stress and thermal stress on the upper and lower surfaces decreases, and the asymmetric stress decreases. When the time is greater than 16s and the temperature is greater than 210°C, the moisture content of the wood decreases, the thermal conductivity deteriorates, the asymmetric stress on the upper and lower surfaces of the ultra-thin fiberboard with melamine impregnated film paper increases, and the heterogeneity increases. However, appropriately increasing the hot pressing time and temperature can accelerate the movement of moisture in the fiberboard, reduce the difference in thermal stress and volume stress on the upper and lower surfaces of the wood, and reduce the heterogeneity of the wood. Therefore, when the hot pressing time is 10-14s and the hot pressing temperature is 200-210℃, the asymmetric stress of the ultra-thin fiberboard with melamine impregnated film facing is the smallest and the curling degree is the smallest.

[0020] Furthermore, in step (3), the specific operation of the water spray treatment is: atomize the water, spray the atomized water with a flow rate of 55-65 ml / s on the unpasted surface of the melamine impregnated film-faced ultra-thin fiberboard 2, once from front to back and once from back to front, each spraying amount of 0.12-0.18 kg, and the total spraying amount of 0.24-0.36 kg. After the upper surface of the melamine impregnated film-faced ultra-thin fiberboard is treated with high temperature, the cross-sectional density increases, but the lower surface is not treated with high temperature. After the thermal stress and volume stress are released, the material will become an asymmetric material. After the water spray treatment, the fiberboard will become softer and more fluid, reducing the volume stress and thermal stress of the melamine impregnated film paper-faced ultra-thin fiberboard, thereby reducing the effect of asymmetric stress. Moreover, wood itself is a non-insulator. When sprayed with water at high temperature, the sprayed water will turn into partial water vapor. The presence of water vapor can increase the temperature of the lower surface of the board. At the same time, the moisture content of the wood increases and the heat conduction speed becomes faster, which can weaken the heterogeneity of the upper and lower surfaces of the melamine-impregnated film-faced ultra-thin fiberboard and reduce the curling degree of the melamine-impregnated film paper-faced ultra-thin fiberboard.

[0021] Furthermore, in step (4), the pressure of the pressurized placement is 0.8-1.2 t. After spraying water, the melamine impregnated film-faced ultra-thin fiberboard softens, and pressurizing the fiberboard can make the fiberboard flat and reduce the degree of curling.

[0022] Furthermore, in step (1), the improved cushion layer is a steel mesh, a high-temperature film and a hard pad. In the traditional process, the cushion layer under the pressing is mostly a steel mesh, a high-temperature film, a high-temperature rubber skin, and a felt. These cushion layers are too soft and lack support for the fiberboard. During the lamination, the fiberboard has a large asymmetry, and the fiberboard is heated unevenly, and the moisture cannot be released. The present invention changes the cushion layer to a steel mesh, a high-temperature film and a hard pad, which increases the hardness, supports the board, and reduces the asymmetry of the ultra-thin fiberboard with melamine impregnated film veneer.

[0023] Furthermore, in step (2), the surface of the anti-curling workbench is in a downward arc shape with an arc of 2.60-2.65 rad. The surface of the anti-curling workbench is in a downward arc shape, which is opposite to the curling direction of the melamine impregnated film-faced ultra-thin fiberboard, and can effectively reduce the curling degree of the melamine impregnated film-faced ultra-thin fiberboard. The surface of a conventional ordinary workbench is a horizontal plane, and the fiberboard placed on it has the problem of curling.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention improves the process and equipment to obtain an anti-curling melamine impregnated film-faced ultra-thin fiberboard with a bending coefficient of less than 5*10 -3, reducing the curl of the melamine impregnated film facing ultra-thin fiberboard, the prepared melamine impregnated film facing ultra-thin fiberboard is flat, ensuring that the impregnated paper can be pressed intact on the melamine impregnated film paper facing ultra-thin fiberboard, reducing the difficulty of re-pasting, improving the utilization rate of the melamine impregnated film facing ultra-thin fiberboard, and improving production efficiency.

[0026] (2) During the lamination process, the melamine impregnated film facing fiberboard is too curled, which can easily cause damage to the board surface and cause surface cracks. The lamination is difficult and requires a lot of manpower and material resources. The present invention can solve the curling problem, save labor, prevent curling from causing damage to the board surface, reduce production costs, and improve economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the verification data diagram of the formula of Experimental Example 1;

[0028] Figure 2 It is a cross-sectional density test of ultra-thin fiberboard with melamine impregnated film facing before lamination;

[0029] Figure 3 It is the cross-sectional density test of the ultra-thin fiberboard with melamine impregnated film facing after lamination;

[0030] Figure 4 It is an ordinary workbench;

[0031] Figure 5 It is an anti-curling workbench;

[0032] Figure 6 It is a schematic diagram of the method for measuring the bending coefficient of ultra-thin fiberboard with melamine impregnated film facing;

[0033] Figure 7 It is the cross-sectional density of the anti-curling melamine impregnated film faced ultra-thin fiberboard before lamination;

[0034] Figure 8 It is the cross-sectional density of the anti-curling melamine-impregnated film-faced ultra-thin fiberboard after lamination;

[0035] Fig. 9 It is the cross-sectional density of the anti-curling melamine impregnated adhesive film facing ultra-thin fiberboard before water spraying and without pressurization, after water spraying but without pressurization, after water spraying but with pressurization, and after water spraying and pressurization;

[0036] Fig.10 It is a process flow chart of anti-curling melamine impregnated film paper facing ultra-thin fiberboard;

[0037] Fig.11 It is a schematic diagram of an ultra-thin fiberboard faced with melamine impregnated film paper. DETAILED DESCRIPTION

[0038] Example 1

[0039] A process for preventing curling of ultra-thin fiberboard with melamine impregnated adhesive film paper facing comprises the following steps:

[0040] (1) placing a 0.8 mm thick melamine impregnated adhesive film paper facing ultra-thin fiberboard on a cushion layer, and hot pressing the ultra-thin fiberboard under a surface pressure of 8 MPa for 8 seconds at a temperature of 185° C., wherein the cushion layer is a steel mesh, a high-temperature film and a hard cushion plate, to obtain a melamine impregnated adhesive film facing ultra-thin fiberboard 1;

[0041] (2) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 1 on an anti-curling workbench with the sticker surface facing upward, and applying a pressure of 450 Pa for 25 seconds to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 2;

[0042] (3) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 2 on a tray, atomizing water, spraying the unpasted surface of the melamine impregnated adhesive film facing ultra-thin fiberboard 2 with a flow rate of 60 ml / s, once from front to back and once from back to front, with each spraying amount of 0.12 kg and a total spraying amount of 0.24 kg, to obtain a melamine impregnated adhesive film facing ultra-thin fiberboard 3;

[0043] (4) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 3 under a pressure of 0.8 t for 36 hours to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 4;

[0044] (5) The melamine impregnated film facing ultra-thin fiberboard 4 is packaged and placed under heavy pressure for 2 days to obtain an anti-curling melamine impregnated film facing ultra-thin fiberboard.

[0045] Example 2

[0046] A process for preventing curling of ultra-thin fiberboard with melamine impregnated adhesive film paper facing comprises the following steps:

[0047] (1) placing a 0.8 mm thick melamine impregnated film-faced ultra-thin fiberboard on a cushion layer, and hot pressing the ultra-thin fiberboard under a surface pressure of 12 MPa for 6 seconds at a temperature of 220° C., wherein the cushion layer is a steel mesh, a high-temperature film and a hard cushion plate, to obtain a melamine impregnated film-faced ultra-thin fiberboard 1;

[0048] (2) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 1 on an anti-curling workbench with the adhesive surface facing upward, and applying a pressure of 550 Pa for 35 seconds to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 2;

[0049] (3) placing the melamine-impregnated adhesive film facing ultra-thin fiberboard 2 on a tray, atomizing water, spraying the unpasted surface of the melamine-impregnated adhesive film facing ultra-thin fiberboard 2 with a flow rate of 65 ml / s, once from front to back and once from back to front, with each spraying amount of 0.18 kg and a total spraying amount of 0.36 kg, to obtain a melamine-impregnated adhesive film facing ultra-thin fiberboard 3;

[0050] (4) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 3 under a pressure of 1.2 t for 20 hours to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 4;

[0051] (5) The melamine impregnated film facing ultra-thin fiberboard 4 is packaged and placed under heavy pressure for 4 days to obtain an anti-curling melamine impregnated film facing ultra-thin fiberboard.

[0052] Example 3

[0053] A process for preventing curling of ultra-thin fiberboard with a thickness of 0.8 mm and melamine impregnated adhesive film paper facing, comprising the following steps:

[0054] (1) placing a melamine impregnated film-faced ultra-thin fiberboard on a cushion layer, and hot pressing the ultra-thin fiberboard under a surface pressure of 10 MPa, for a hot pressing time of 14 seconds and a hot pressing temperature of 200° C., wherein the cushion layer is a steel mesh, a high-temperature film and a hard cushion plate, to obtain a melamine impregnated film-faced ultra-thin fiberboard 1;

[0055] (2) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 1 on an anti-curling workbench with the adhesive surface facing upward, and applying a pressure of 500 Pa for 30 seconds to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 2;

[0056] (3) placing the melamine-impregnated adhesive film facing ultra-thin fiberboard 2 on a tray, atomizing water, spraying the unpasted surface of the melamine-impregnated adhesive film facing ultra-thin fiberboard 2 with a flow rate of 55 ml / s, once from front to back and once from back to front, with each spraying amount of 0.15 kg and a total spraying amount of 0.30 kg, to obtain a melamine-impregnated adhesive film facing ultra-thin fiberboard 3;

[0057] (4) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 3 under a pressure of 1.0 t for 24 hours to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 4;

[0058] (5) The melamine impregnated film facing ultra-thin fiberboard 4 is packaged and placed under heavy pressure for 2 days to obtain an anti-curling melamine impregnated film facing ultra-thin fiberboard.

[0059] Example 4

[0060] A process for preventing curling of ultra-thin fiberboard with a thickness of 0.8 mm and melamine impregnated adhesive film paper facing, comprising the following steps:

[0061] (1) placing a melamine impregnated film-faced ultra-thin fiberboard on a cushion layer, and hot pressing the ultra-thin fiberboard at a surface pressure of 12 MPa for 10 seconds at a temperature of 210° C., wherein the cushion layer is a steel mesh, a high-temperature film and a hard cushion plate, to obtain a melamine impregnated film-faced ultra-thin fiberboard 1;

[0062] (2) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 1 on an anti-curling workbench with the adhesive surface facing upward, and applying a pressure of 450 Pa for 28 seconds to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 2;

[0063] (3) placing the melamine-impregnated adhesive film facing ultra-thin fiberboard 2 on a tray, atomizing water, spraying the unpasted surface of the melamine-impregnated adhesive film facing ultra-thin fiberboard 2 with a flow rate of 60 ml / s, once from front to back and once from back to front, with each spraying amount of 0.17 kg and a total spraying amount of 0.34 kg, to obtain a melamine-impregnated adhesive film facing ultra-thin fiberboard 3;

[0064] (4) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 3 under a pressure of 1.1 t for 30 hours to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 4;

[0065] (5) The melamine impregnated film facing ultra-thin fiberboard 4 is packaged and placed under heavy pressure for 3 days to obtain an anti-curling melamine impregnated film facing ultra-thin fiberboard.

[0066] Comparative Example 1

[0067] A process for preventing curling of ultra-thin fiberboard with a thickness of 0.8 mm and melamine impregnated adhesive film paper facing, comprising the following steps:

[0068] (1) placing a melamine impregnated adhesive film paper facing ultra-thin fiberboard on a cushion layer, and hot pressing the ultra-thin fiberboard under a surface pressure of 8 MPa, a hot pressing time of 8 seconds, and a hot pressing temperature of 185° C., wherein the cushion layer is a steel mesh, a high-temperature film, a high-temperature rubber skin, and a felt, to obtain a melamine impregnated adhesive film facing ultra-thin fiberboard 1;

[0069] (2) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 1 on an anti-curling workbench with the adhesive surface facing upward, and applying a pressure of 550 Pa for 25 seconds to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 1;

[0070] (3) placing the melamine-impregnated adhesive film facing ultra-thin fiberboard 2 on a tray, atomizing water, spraying the unpasted surface of the melamine-impregnated adhesive film facing ultra-thin fiberboard 2 with a flow rate of 60 ml / s, once from front to back and once from back to front, with each spraying amount of 0.12 kg and a total spraying amount of 0.24 kg, to obtain the melamine-impregnated adhesive film facing ultra-thin fiberboard 2;

[0071] (4) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 3 under a pressure of 0.8 t for 36 hours to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 3;

[0072] (5) The melamine impregnated film facing ultra-thin fiberboard 4 is packaged and placed under heavy pressure for 2 days to obtain an anti-curling melamine impregnated film facing ultra-thin fiberboard.

[0073] Comparative Example 2

[0074] A process for preventing curling of ultra-thin fiberboard with a thickness of 0.8 mm and melamine impregnated adhesive film paper facing, comprising the following steps:

[0075] (1) placing a melamine impregnated adhesive film paper facing ultra-thin fiberboard on a cushion layer, and hot pressing the ultra-thin fiberboard under a surface pressure of 10 MPa, a hot pressing time of 14 seconds, and a hot pressing temperature of 200° C., wherein the cushion layer is a steel mesh, a high-temperature film, and a hard cushion plate, to obtain a melamine impregnated adhesive film facing ultra-thin fiberboard 1;

[0076] (2) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 1 on a common workbench with the sticker surface facing upward, applying a pressure of 450 Pa for 30 seconds, and obtaining the melamine impregnated adhesive film facing ultra-thin fiberboard 2;

[0077] (3) placing the melamine-impregnated adhesive film facing ultra-thin fiberboard 2 on a tray, atomizing water, spraying the unpasted surface of the melamine-impregnated adhesive film facing ultra-thin fiberboard 2 with a flow rate of 60 ml / s, once from front to back and once from back to front, with each spraying amount of 0.15 kg and a total spraying amount of 0.30 kg, to obtain a melamine-impregnated adhesive film facing ultra-thin fiberboard 3;

[0078] (4) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 3 under a pressure of 1.0 t for 24 hours to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 4;

[0079] (5) The melamine impregnated film facing ultra-thin fiberboard 4 is packaged and placed under heavy pressure for 2 days to obtain an anti-curling melamine impregnated film facing ultra-thin fiberboard.

[0080] Note: The surface of the common workbench in step (2) is a horizontal plane.

[0081] Experimental Example 1: Verification of the formula

[0082] Set the equation y=ax 2 -h simulates the bending shape of the ultra-thin fiberboard with melamine impregnated film facing. In an environment with a temperature of 25°C and a humidity of 30% rh, the ultra-thin fiberboard with a size of 600 mm*600 mm is bent upward. Figure 6 The measurement method shown is to measure the distance from the ground to the highest point of curling of the ultra-thin fiberboard with melamine impregnated film, recorded as h1, measure the board spacing at the highest point of bending of the ultra-thin fiberboard with melamine impregnated film, recorded as l1, then measure the distance from the ground to the middle point of curling of the ultra-thin fiberboard with melamine impregnated film, recorded as h2, measure the board spacing at the middle point of bending of the ultra-thin fiberboard with melamine impregnated film, recorded as l2, finally measure the distance from the ground to the point where the ultra-thin fiberboard with melamine impregnated film curling is close to the ground, recorded as h3, measure the board spacing at the middle point of bending of the ultra-thin fiberboard with melamine impregnated film, recorded as l3, and calculate according to the above equations to obtain the bending coefficients a1, a2, a3 and the average value a respectively. The above tests were measured three times, and the average value was removed. The results are listed in Table 2.

[0083] Table 2. Bending coefficient a of ultra-thin fiberboard with melamine impregnated film paper facing

[0084]

[0085] From the attached Figure 1 From Table 2, we can see that when h is 14.5 cm and l is 38.0 cm, a is 40.16*10 -3 , when h is 6.0cm and l is 24.5cm, a is 39.98*10 -3 , when h is 3.5cm and l is 18.5cm, a is 40.91*10 -3 , the average value a is 40.35*10 -3 It can be seen that the bending coefficient a obtained by measuring the bending h and l of the ultra-thin fiberboard with melamine impregnated film paper at different positions is not much different, especially when measuring at the highest point of curling of the ultra-thin fiberboard with melamine impregnated film paper, the bending coefficient a obtained is closest to the average value a, indicating that the bending coefficient a calculated is most accurate when measuring at the highest point of curling of the ultra-thin fiberboard with melamine impregnated film paper.

[0086] Experimental Example 2 Curl Degree Test of Ultra-thin Fiberboard with Melamine Impregnated Film Finish of Different Thicknesses

[0087] The curling degree of ultra-thin fiberboard with melamine impregnated film facing of different thicknesses was tested three times and the average value was taken. The test data are listed in Table 3.

[0088] Curl degree test method: In an environment with a temperature of 25°C and a humidity of 30% rh, the curl degree of the melamine impregnated film facing ultra-thin fiberboard is tested, and the equation y=ax is set. 2 -h simulates the bending shape of fiberboard. For a 600 mm*600 mm melamine impregnated film-faced ultra-thin fiberboard, measure the height h from the ground, measure the distance l from A to B, substitute it into the equation, and the value a obtained is the bending coefficient obtained to determine the bending degree of the board. The larger a is, the greater the bending degree is, and vice versa, the smaller the bending degree is.

[0089] Table 3. Curling degree of ultra-thin fiberboard with melamine impregnated film facing of different thicknesses

[0090]

[0091] From Table 3, we can see that the bending coefficient of the fiberboard with a thickness of 0.8 mm is 73.75*10 -3 , the bending coefficient of the fiberboard with a thickness of 1.0 mm is 71.66*10 -3 The bending coefficient of the fiberboard with a thickness of 1.2 mm is 70.95*10 -3 , the bending coefficient of the fiberboard with a thickness of 1.4 mm is 69.35*10 -3 , the bending coefficient of the fiberboard with a thickness of 1.4 mm is 68.21*10 -3 This shows that the thinner the fiberboard is, the greater the bending coefficient and the greater the degree of curling.

[0092] Experimental Example 3

[0093] The curling degree of the anti-curling melamine impregnated film facing ultra-thin fiberboard of Example 1 and Comparative Example 1 was tested three times respectively, and the average value was taken. The test data are listed in Table 4.

[0094] Table 4. Comparison of curling degree of ultra-thin fiberboard with anti-curling melamine impregnated film before and after cushion layer improvement

[0095]

[0096] From Table 4, it can be seen that the bending coefficient of the anti-curling melamine impregnated film facing ultra-thin fiberboard finally obtained before the cushion layer is improved is 72.36*10 -3 After the cushion layer is improved, the bending coefficient of the anti-curling melamine impregnated film facing ultra-thin fiberboard is 32.32*10 -3 The greater the bending coefficient, the greater the curling degree, which means that after the cushion layer is improved in the present invention, the bending coefficient of the ultra-thin fiberboard with melamine impregnated film facing is reduced and the curling degree is reduced.

[0097] Experimental Example 4

[0098] Step (2) hot pressing the melamine impregnated adhesive film facing ultra-thin fiberboard at a surface pressure of 10 MPa, the hot pressing time is 6 s, 8 s, 10 s, 12 s, 14 s, 16 s, 18 s, and the hot pressing temperature is 185° C., to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 2;

[0099] The other steps are the same as those in Example 3.

[0100] The curling degree of the anti-curling melamine impregnated film facing ultra-thin fiberboard under different hot pressing times was tested three times and the average value was taken. The test data are listed in Table 5.

[0101] Table 5. Comparison of curling degree of ultra-thin fiberboard with anti-curling melamine impregnated film facing under different hot pressing time

[0102]

[0103] As shown in Table 5, when the ultra-thin fiberboard with melamine impregnated adhesive film is hot-pressed for different time periods, the bending coefficient first decreases and then increases with the increase of time. When the hot-pressing time is 8-16s, the change range of the ultra-thin fiber bending coefficient is small. Among them, when the hot-pressing time is 10-14s, the bending coefficient of the ultra-thin fiberboard with melamine impregnated adhesive film is the smallest, and the curling degree is the smallest. This indicates that the present invention can reduce the curling degree of the ultra-thin fiberboard with melamine impregnated adhesive film by adjusting the hot-pressing time.

[0104] Experimental Example 5

[0105] Step (2) hot pressing the melamine impregnated adhesive film paper facing ultra-thin fiberboard at a surface pressure of 10 MPa, the hot pressing time is 10 seconds, and the hot pressing temperatures are 185° C., 195° C., 200° C., 205° C., 210° C., 215° C., and 220° C., respectively, to obtain the melamine impregnated adhesive film paper facing ultra-thin fiberboard 2;

[0106] The other steps are the same as those in Example 3.

[0107] The curling degree of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard under different hot pressing temperatures was tested three times and the average value was taken. The test data are listed in Table 6.

[0108] Table 6. Comparison of curling degree of anti-curling melamine impregnated film paper facing ultra-thin fiberboard at different hot pressing temperatures

[0109]

[0110] As can be seen from Table 6, as the temperature increases, the bending coefficient of the melamine impregnated film paper facing ultra-thin fiberboard first decreases and then increases. When the temperature is 195-215°C, the change range of the bending coefficient of the melamine impregnated film paper facing ultra-thin fiberboard is small. At 200-210°C, the bending coefficient is the smallest, and the curling degree of the melamine impregnated film paper facing ultra-thin fiberboard is the smallest. This shows that the present invention can reduce the curling degree of the melamine impregnated film paper facing ultra-thin fiberboard by adjusting the hot pressing temperature.

[0111] Experimental Example 6

[0112] The curling degree of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard of Example 3 and Comparative Example 2 was tested three times respectively, and the average value was taken. The test data are listed in Table 7.

[0113] Table 7. Comparison of curling degree of anti-curling melamine impregnated film paper veneer ultra-thin fiberboard after treatment on ordinary workbench and anti-curling workbench

[0114]

[0115] From Table 7, we can see that after the melamine impregnated film paper facing ultra-thin fiberboard is placed on a common workbench for processing, the bending coefficient of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard is 12.66*10 -3 After the melamine impregnated film paper facing ultra-thin fiberboard is placed on the anti-curling workbench of the present invention for treatment, the bending coefficient of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard is 5.72*10 -3 It can be seen that the anti-curling melamine impregnated film paper facing ultra-thin fiberboard treated by the anti-curling workbench of the present invention has a reduced bending coefficient and a reduced curling degree. This indicates that the anti-curling workbench of the present invention can significantly reduce the curling degree of the melamine impregnated film paper facing ultra-thin fiberboard.

[0116] Experimental Example 7

[0117] Under the same hot pressing temperature and time, the curling degree of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard without water spraying and pressurization, water spraying but without pressurization, without water spraying but pressurization, and water spraying and pressurization was tested three times respectively, and the average value was taken. The test data are listed in Table 8.

[0118] Table 8. Comparison of curling degree of ultra-thin fiberboard with anti-curling melamine impregnated film paper facing

[0119]

[0120] From Table 8, we can see that the bending coefficient of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard without water spraying and pressure is 67.35*10 -3The bending coefficient of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard sprayed with water but not pressurized is 42.93*10 -3 The bending coefficient of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard without water spraying but pressurized is 48.35*10 -3 The bending coefficient of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard sprayed with water and pressurized is 3.97*10 -3 It can be seen that the bending coefficient of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard after water spraying and pressurization is the smallest, indicating that pressurization after water spraying can reduce the curling degree of the melamine impregnated film paper facing ultra-thin fiberboard.

[0121] Experimental Example 8 Sectional Density Test of Ultra-Thin Fiberboard with Melamine Impregnated Film Paper Face before and after Lamination

[0122] Select the M104 warm oak impregnation paper of fine board facing paper, the size of fiberboard and impregnation paper is 600 mm*600 mm, set the unit pressure at 2 MPa (the corresponding surface pressure in the factory is 10 MPa, and the corresponding surface pressure in the laboratory is 10-11 MPa), and press the ultra-thin fiberboard with melamine impregnated film paper. The same ultra-thin fiberboard with melamine impregnated film paper facing is tested for cross-sectional density before and after pressing, and the test is carried out three times respectively, and the average value is taken. The test results are attached Figure 1-2 and Table 9.

[0123] Table 9. Sectional density test of ultra-thin fiberboard with melamine impregnated film paper facing

[0124]

[0125] By the attached Figure 2 , Attachment Figure 3 , Attachment Figure 7 , Attachment Figure 8 As can be seen from Table 9, when the cross-sectional density of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard before lamination was tested, the difference between the cross-sectional density of the A and B sides was not much, indicating that the melamine impregnated film paper facing ultra-thin fiberboard that was not treated with high temperature and high pressure was a homogeneous material; when the cross-sectional density of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard was tested after lamination, the density of the side with impregnated paper was significantly greater than the density of the side without impregnated paper, indicating that the pressed fiberboard treated with high temperature and high pressure was a non-homogeneous material.

[0126] Experimental Example 9 Sectional Density Test of Anti-curling Melamine Impregnated Film Paper Faced Ultra-thin Fiberboard Before and After Water Spraying and Pressurization

[0127] Under the same hot pressing temperature and time, the cross-sectional density of the anti-curling melamine impregnated film paper facing ultra-thin fiberboard without water spraying and pressurization, water spraying but without pressurization, without water spraying but pressurization, and water spraying and pressurization was tested three times respectively, and the average value was taken. The test data are listed in Table 10.

[0128] Table 10. Comparison of cross-sectional density of anti-curling melamine impregnated film paper facing ultra-thin fiberboard

[0129] From the attached Fig. 9 As shown in Table 10, the density of the unpasted surface of the melamine impregnated adhesive paper facing ultra-thin fiberboard without water spraying and pressure treatment is 1108 kg·m -3 , the density of the sticker surface is 1687 kg·m -3 , melamine impregnated paper faced ultra-thin fiberboard with water spraying but not pressure treatment, density of the unfaced side is 1123 kg·m -3 , the density of the sticker surface is 1540kg·m -3 The density of the unpainted surface of the ultra-thin fiberboard with melamine impregnated paper is 1134 kg·m -3 , the density of the sticker surface is 1618 kg·m -3 , water-sprayed and pressure-treated melamine-impregnated paper-faced ultra-thin fiberboard, density of the unfaced surface is 1112 kg·m -3 , the density of the sticker surface is 1159 kg·m -3 It can be seen that the density of the melamine impregnated film paper facing ultra-thin fiberboard treated with water spraying and pressure application is not much different between the surface without paper and the surface with paper, indicating that the material treated with water spraying and pressure application is a homogeneous material. It can be shown that the anti-curling process method of the present invention can change the heterogeneity of the melamine impregnated film paper facing ultra-thin fiberboard and reduce the curling degree of the melamine impregnated film paper facing ultra-thin fiberboard.

[0130] In summary, after the melamine-impregnated film paper facing ultra-thin fiberboard is subjected to a pressing process in the present invention, the melamine-impregnated film paper facing ultra-thin fiberboard becomes a non-homogeneous material and curls. The present invention reduces the non-homogeneity of the melamine-impregnated film paper facing ultra-thin fiberboard and reduces the curling degree of the fiberboard through the improvement of the process and equipment. The prepared melamine-impregnated film paper facing ultra-thin fiberboard is flat, ensuring that the impregnated paper can be pressed intact on the melamine-impregnated film paper facing ultra-thin fiberboard, reducing the difficulty of re-pasting, improving the utilization rate of the melamine-impregnated film paper facing ultra-thin fiberboard, and improving production efficiency.

Claims

1. A process for preventing curling of ultra-thin fiberboard with melamine impregnated film paper facing, characterized in that: The following steps are involved: (1) placing the melamine impregnated adhesive film paper facing ultra-thin fiberboard on the improved cushion layer, and performing hot pressing at a surface pressure of 8-12 MPa to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 1; (2) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 1 on an anti-curling workbench with the adhesive surface facing upward, applying a pressure of 450-550 Pa for 25-35 seconds, and obtaining the melamine impregnated adhesive film facing ultra-thin fiberboard 2; (3) placing the melamine impregnated film-faced ultra-thin fiberboard 2 on a pallet and spraying it with water to obtain the melamine impregnated film-faced ultra-thin fiberboard 3; (4) placing the melamine impregnated adhesive film facing ultra-thin fiberboard 3 under pressure for 20-36 hours to obtain the melamine impregnated adhesive film facing ultra-thin fiberboard 4; (5) Packing the melamine impregnated film facing ultra-thin fiberboard 4, and placing it under heavy pressure for 2-4 days to obtain an anti-curling melamine impregnated film facing ultra-thin fiberboard; The bending coefficient of the anti-curling melamine impregnated film facing ultra-thin fiberboard is less than 5*10 -3 In step (3), the specific operation of the water spray treatment is: atomize the water, spray the atomized water with a flow rate of 55-65 ml / s on the unpasted surface of the melamine impregnated film-faced ultra-thin fiberboard 2, once from front to back and once from back to front, each time the water spraying amount is 0.12-0.18 kg, and the total water spraying amount is 0.24-0.36 kg.

2. The anti-curling process of the melamine impregnated film paper facing ultra-thin fiberboard according to claim 1, characterized in that: In step (1), the thickness of the melamine impregnated adhesive film paper facing ultra-thin fiberboard is ≤1.5 mm.

3. The anti-curling process of the melamine impregnated film paper facing ultra-thin fiberboard according to claim 1, characterized in that: In step (1), the hot pressing time is 8-16s, and the hot pressing temperature is 195-215°C.

4. The anti-curling process of the ultra-thin fiberboard with melamine impregnated film paper facing according to any one of claims 1 to 3, characterized in that: In step (1), the hot pressing time is 10-14s and the hot pressing temperature is 200-210°C.

5. The anti-curling process of the melamine impregnated film paper facing ultra-thin fiberboard according to claim 4, characterized in that: In step (4), the pressure of the pressurized placement is 0.8-1.2t.

6. The anti-curling process of the melamine impregnated film paper facing ultra-thin fiberboard according to claim 1, characterized in that: In step (1), the improved cushion layer is a steel mesh, a high-temperature film and a hard cushion plate.

7. The anti-curling process of the melamine impregnated film paper facing ultra-thin fiberboard according to claim 6, characterized in that: In step (2), the surface of the anti-curling workbench is a downward arc with an arc of 2.60-2.65 rad.

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