Composite fiber density board and method for manufacturing the same

Abstract

The present application relates to the technical field of artificial board, and particularly relates to a composite fiber density board and a preparation method thereof. The method comprises the following steps: a mixed fiber material and a binder are laid on a continuous flat pressing machine, the binder can be a powder or a liquid binder; a fiber web output device is configured, and a fiber web is covered on the upper and lower surfaces or any surface of the fiber material blank, the fiber web can be treated by a coupling agent; a layer of water-based acrylic paint is sprayed on the upper surface of the laid board blank to improve the surface density of the board and increase the strength of the board; the composite board blank composed of the fiber web and the fiber material enters a hot pressing section of the continuous flat pressing machine, and is pressed under high temperature and high pressure, the fiber web and the fiber material are combined into one body under the action of the binder, the acrylic paint and the high temperature and high pressure, and the composite fiber density board with the high-strength fiber web on the surface is obtained. The high-strength fiber web which is combined on the surface of the board improves the strength of the density board and widens the application range of the density board.

Description

Technical Field

[0001] This invention relates to the field of engineered wood products technology, and in particular to a composite fiber density board and its preparation method. Background Technology

[0002] Boards made from inorganic fibers such as mineral wool are widely used in civil, industrial, and commercial decoration due to their excellent fire resistance, moisture resistance, dimensional stability, and chemical stability. Continuous flat pressing technology can be used to produce these inorganic fiber boards, ensuring uniform thickness and controllable density. However, similar to organic fiber boards, single-material inorganic fiber boards have inherent limitations in mechanical properties, particularly low tensile strength, high brittleness, and poor bending resistance. This severely restricts their application in situations requiring high impact resistance and structural strength (such as building exterior cladding and composite wall panels). To enhance the mechanical properties of fiber boards, common practices include: 1. Increasing the amount of adhesive to improve bonding strength, but this increases costs and reduces the fire resistance rating of the board. 2. Composite a layer of high-strength fiber mesh (such as glass fiber mesh or basalt fiber mesh) onto the surface of the finished board. This reinforcing mesh can effectively withstand tensile stress, thereby significantly improving the overall integrity, tear resistance, and deformation resistance of the board. Currently, the process of composite fiber mesh with fiber boards mainly faces the following challenges: First, the composite process is inefficient: after the sheet material is pressed and formed, a separate gluing and lamination process is performed. This method disrupts the continuity of production, increases energy consumption and costs, and the interfacial bonding strength of the secondary composite is often limited by the surface treatment effect, posing a potential risk of delamination. Second, the surface quality of the sheet material is unstable, with the presence of micropores or microcracks. For sheets that are not sanded later, this defect is very detrimental to the coating process.

[0003] Therefore, existing technologies for inorganic fiber boards present two prominent problems: the post-composite process cannot meet the requirements of integrated production and high strength; and the surface quality is difficult to meet the requirements of coating processes. Developing an online composite method that can adapt to the characteristics of continuous flat pressing processes, achieve high bonding strength, and improve surface quality has become a pressing technical challenge in this field. Summary of the Invention

[0004] This invention provides a composite fiber density board, which offers a high-strength fiber composite material. This invention is also applicable to strength enhancement of organic boards (such as wood fiberboard).

[0005] In a first aspect, embodiments of the present invention provide a method for preparing a composite fiber density board, comprising: In the continuous flat roller paving section, fiber material mixed with binder is paved. The binder includes powder or liquid binder, and the fiber material includes organic or inorganic fibers, or a mixture of both. Equipped with a fiber web output device, the fiber web is covered on the upper and lower surfaces or any one side of the sheet blank. The fiber web is woven from glass fiber or carbon fiber and is treated with a coupling agent to improve the interfacial bonding properties. Equipped with a spraying device, a layer of water-based acrylic coating is sprayed onto the surface of the laid slab to improve the surface density of the slab and increase its strength. The composite board blank composed of the fiber web and fiber material enters the hot pressing section of a continuous flat press. Under high temperature and high pressure, the fiber web and fiber material are bonded together by the binder and under high temperature and high pressure to obtain a composite fiber density board with a high-strength fiber web on the surface.

[0006] Optionally, the fiber material is organic fiber or inorganic fiber, or a mixture of both, and the fiber material has been uniformly mixed with the binder; the fiber diameter is 0.5-10 micrometers and the length is 1-10 micrometers; the binder is a liquid or powder binder, such as phenolic resin adhesive, and the weight ratio of the binder to the fiber is 5%-18%.

[0007] Optionally, after covering the upper and lower surfaces or any one side of the sheet blank with a fiber mesh, before spraying water-based acrylic, the process further includes: The fiber mesh-bonded plate blank is pre-cured using the upper and lower pressure plates of a hot pressing device; wherein, a deformable plate is provided on the pressing surface of the upper and lower pressure plates; The deformable plate includes a deformable plate made of shape memory polymer. The glass transition temperature of the deformable plate is lower than the curing temperature but higher than the room temperature. The pre-curing treatment includes room temperature flat pressing and high temperature curing in sequence. The ambient temperature pressure adjustment includes applying pressure at 0.2 MPa for 30 seconds; The high-temperature curing process includes raising the temperature gradient to 120°C and holding it at that temperature for 8 minutes, wherein the heating rate is 10°C / min, and the pressure is increased to 0.8MPa during the heating process, wherein the pressure gradient is 0.078MPa / min. The upper pressure plate and the lower pressure plate each have a release layer on their deformable plates, the release layer comprising a PET film substrate core solid silicone coating layer.

[0008] Optionally, the fiber web is woven from glass fiber or carbon fiber, with a mesh size of 0.1mm x 0.1mm to 10mm x 10mm. The fiber web is modified with a coupling agent to change its interfacial properties and improve its bonding strength with the adhesive.

[0009] Optionally, the spraying device uses an air atomizer with a pressure of 0.3-1.0 MPa and a paint spraying rate of 30-200 g / m³. 2 .

[0010] Optionally, the fiber web output device includes a fiber spool and a curved feeder. The fiber spool is used to hold the wound fiber web. The fiber web enters one end of the curved space of the curved feeder through the strip-shaped outlet of the fiber spool. The curved space is part of a cylindrical surface. The fiber web exits from the opening at the other end of the curved space. A pressure roller is provided at one end of the curved space by a spring. The pressure roller and the opening at one end of the curved space clamp the fiber web.

[0011] Optionally, the fiber web is pre-coated with microspheres and / or short fibers at intervals.

[0012] Optionally, the microspheres include polymer elastic microspheres and / or hollow glass microspheres. The microspheres are bonded to the fiber mesh on the side for bonding with the plate blank by mixing with an adhesive. The diameter of the microspheres is 10~135μm. The short fibers are vertically implanted into the fiber web by electrostatic action on one side for composite with the board blank, and the length of the short fibers is 200μm~5mm.

[0013] Optionally, the high-temperature and high-pressure process parameters are as follows: The pressure setting value of the press inlet zone of the continuous flat press is 20-30% of the maximum pressure value, and the temperature value is 120-150℃. The time of the plate blank in the inlet zone accounts for 20-30% of the total time. After the sheet blank enters the middle zone of the continuous flat press, it is first pressurized to 50-60% of the maximum pressure value, then instantly reduced to 10-20% of the maximum pressure value, and then gradually increased to 70-80% of the maximum pressure value. The temperature in the middle zone is set to 160-280℃. The sheet blank spends 50-60% of the total time in the middle zone. The time ratio of the three pressure stages in the middle zone is (65-70):(5-15):(20-25). After the sheet blank enters the exit zone, the pressure increases to 100% of the maximum pressure value, and the temperature drops by 0~20℃ compared to the middle zone. The sheet blank spends 20~30% of the total time in the exit zone. The maximum pressure value is 1~8MPa.

[0014] Secondly, embodiments of the present invention provide a composite fiber density board, prepared according to any of the preparation methods described above.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: In this embodiment, the fiber mesh is first preliminarily laminated onto the board blank, and then acrylic coating is sprayed on. Under the combined action of high temperature and pressure, adhesive and acrylic coating, the preliminarily laminated fiber mesh is further firmly bonded to the board blank, which increases the degree of bonding between the fiber mesh and the board. At the same time, it improves the surface quality of the board and enhances the overall performance of the board. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of a continuous hot-pressing device for composite fiber density board provided by the present invention; Figure 2 This is a schematic diagram of the composition of a fiber web output device provided by the present invention; Figure 3 This is a schematic diagram of a spray device provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] In the description of the embodiments of the present invention, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or stated, the term "multiple" refers to two or more; the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0020] In this specification, it should be understood that the directional terms such as "upper" and "lower" used in the description of the embodiments of the present invention are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of the present invention. Furthermore, in the context, it should also be understood that when it is mentioned that one element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0021] Please refer to Figure 1 This invention provides a continuous flat pressing device, which includes: a lower fiber web output device 1, a lower surface fiber web 2, a paving machine 3, an upper fiber web output device 4, an upper surface fiber web 5, fiber material 6, a paving section conveyor belt 7, a spraying device 8, and a hot press 9. The lower fiber web output device 1 outputs the fiber web 2 from the lower surface of the board. The lower fiber web is output through the fiber roller 1-1, passes through the lower feeder 1-2, and is covered on the conveyor belt 7 of the paving section; The paving machine 3 in the paving section evenly spreads the fiber material 6 onto the conveyor belt 7 in the paving section; The upper fiber web output device 4 outputs the fiber web 5 on the upper surface of the board. The upper fiber web is output through the fiber roller 4-1 and then through the upper feeder 4-2 to cover the laid fiber material 6, forming a board blank with composite fiber web. The spraying device 8 uses a high-pressure air source tank 8-1 to atomize the acrylic paint in the acrylic paint tank 8-2 and spray it evenly onto the slab blank through the bracket and nozzle 8-3. The slab blank enters the hot press 9, passing through the inlet, middle section, and outlet. Under the high temperature and pressure provided by the hot press, as well as the action of the binder and acrylic coating, the fiber material and fiber web are firmly bonded together to obtain a composite fiber density board with high strength and good surface quality.

[0022] Based on the aforementioned continuous flat pressing device, this application provides a method for preparing composite fiber density board, comprising: In the continuous flat roller paving section, fiber material mixed with binder is paved. The binder includes powder or liquid binder, and the fiber material includes organic or inorganic fibers, or a mixture of both. Equipped with a fiber web output device, the fiber web is covered on the upper and lower surfaces or any one side of the sheet blank. The fiber web is woven from glass fiber or carbon fiber and is treated with a coupling agent to improve the interfacial bonding properties. Equipped with a spraying device, a layer of water-based acrylic coating is sprayed onto the surface of the laid slab to improve the surface density of the slab and increase its strength. The composite board blank composed of the fiber web and fiber material enters the hot pressing section of a continuous flat press. Under high temperature and high pressure, the fiber web and fiber material are bonded together by the binder and under high temperature and high pressure to obtain a composite fiber density board with a high-strength fiber web on the surface.

[0023] In this embodiment, the fiber mesh can be a high-strength fiber mesh such as glass fiber mesh or carbon fiber mesh, with a mesh size between 0.1mm x 0.1mm and 10mm x 10mm.

[0024] In some embodiments of the present invention, a release layer is provided between the steel strip of the hot press and the sheet material. The release layer can be silicone-coated kraft paper, high-temperature cloth with Teflon coating, etc. The thickness of the release layer is 10-50 micrometers. The release layer has a good release effect, ensuring that the sheet material and the steel strip do not stick together and do not wrinkle.

[0025] The fiber web can be laminated on a continuous production line using the aforementioned continuous flat pressing device. When the pressure is high during the continuous hot pressing process, pre-curing can be performed beforehand to prevent the fibers from being flattened. Pre-curing not only prevents fiber flattening but also eliminates the need to modify the existing production line. The pre-cured fiber web-coated board blank can be placed directly on the existing continuous flat pressing device for lamination; only the process parameters need to be adjusted accordingly.

[0026] Methods for pre-curing fiber webs include: The fiber mesh-bonded plate blank is pre-cured using the upper and lower pressure plates of a hot pressing device; wherein, a deformable plate is provided on the pressing surface of the upper and lower pressure plates; The deformable plate includes a deformable plate made of shape memory polymer. The glass transition temperature of the deformable plate is lower than the curing temperature but higher than the room temperature. The pre-curing treatment includes room temperature flat pressing and high temperature curing in sequence. The ambient temperature pressure adjustment includes applying pressure at 0.2 MPa for 30 seconds; The high-temperature curing process includes raising the temperature gradient to 120°C and holding it at that temperature for 8 minutes, wherein the heating rate is 10°C / min, and the pressure is increased to 0.8MPa during the heating process, wherein the pressure gradient is 0.078MPa / min. The upper pressure plate and the lower pressure plate each have a release layer on their deformable plates, the release layer comprising a PET film substrate core solid silicone coating layer.

[0027] In this embodiment, the fiber web is first preliminarily composited onto the board blank, and then the board blank is formed by continuous flat pressing. During the continuous flat pressing process, the preliminarily composited fiber web is further bonded to the board blank under the action of high temperature and high pressure, which increases the degree of bonding between the fiber web and the board and improves the comprehensive performance of the composite material.

[0028] During the initial pressing and pre-curing process, this application incorporates a deformable plate on the pressure plate. This design allows the deformable plate to deform according to the shape of the fiber mesh when the upper and lower pressure plates compress it. The compression displacement is greater at the mesh openings, while the compression is less at the fiber mesh body due to the mesh's resistance. This causes the deformed plate to partially enclose the fiber mesh body, applying pressure to its interior and ensuring the pre-applied adhesive fully impregnates the gaps within the fiber mesh. After curing, the cured adhesive provides pressure protection for the fiber mesh. It should be noted that without this cured adhesive protecting the fiber bundles, the fiber bundles may be flattened under the greater pressure of subsequent continuous pressing, leading to structural damage.

[0029] In this embodiment, the adhesive layer applied in the early stages is not uniform. By pressing at room temperature (when the deformable plate is relatively hard), the applied pressure (flat pressure) forces the fiber mesh into the adhesive layer, resulting in a more uniform adhesive thickness and distribution. As the temperature rises, the deformable plate softens, partially encasing the fiber bundles and allowing the gaps within the fiber bundles to be fully impregnated with the adhesive. The adhesive then gradually cures at high temperature, completing the impregnation and pre-curing of the fiber bundles. Of course, other materials with varying hardness are also within the scope of this application, such as pressure-resistant membranes filled with water, achieving the above functions through the phase change of ice and water.

[0030] Understandably, fillers such as carbon nanotubes can be added to shape memory polymers to increase their thermal conductivity.

[0031] In this embodiment, the composite release layer has good elastic deformation, can deform with the deformable plate, and will not produce wrinkles.

[0032] In some embodiments of the present invention, the fiber web is pre-composite with microspheres and / or short fibers at intervals.

[0033] Online synchronous lamination faces severe process compatibility issues: attempting to synchronize fiber web laying with the pressing process of inorganic fiberboard blanks presents unique and severe challenges due to the high-temperature and high-pressure environment within the continuous flat press, where thermal decomposition and curing behaviors are more complex. Under high-temperature and high-pressure conditions, the discharge of residual volatile components inside the board blank can easily lead to air resistance if obstructed by the surface fiber web and adhesives, resulting in pores, delamination, and even "lifting" of the fiber web, severely damaging the integrity of the composite interface.

[0034] To address this issue, microspheres or short fibers are pre-spaced on the fiber mesh to create microchannels for gas discharge during subsequent continuous pressing. Specifically, the microspheres or short fibers create a regular, three-dimensional spatial network supported by countless tiny "pillars" between the fiber mesh and the slab surface, rather than a completely dense planar contact. While these microspheres or short fibers exist as "pillars," they are themselves impermeable entities. Crucially, the spaces between these pillars are interconnected, forming a stable, three-dimensional network of channels. During the initial stages of continuous hot pressing, when the slab is compressed and generates a large amount of water vapor and volatiles, these gases can easily reach the voids beneath the fiber mesh. They flow laterally along this network of channels, defined by the boundaries of the "pillars" and spanning the width of the slab, and eventually discharge smoothly from the sides of the slab. This cleverly avoids the gas being "blocked" by the intact fiber mesh and adhesive layer when escaping upwards, thus preventing gas resistance.

[0035] It should be noted that in the early stage of continuous hot pressing (venting stage): the selected microspheres or short fibers have high compressive strength, capable of resisting the low pressure set at the beginning of hot pressing to promote venting. Under this pressure, they only undergo slight elastic deformation, sufficient to keep the venting channels unobstructed. In the later stage of continuous hot pressing (compacting and curing stage): when venting is basically completed and the press enters the final high-pressure compaction stage, the pressure will increase significantly. At this time, the "compressibility" of these microspheres or short fibers begins to play a role. For polymer microspheres: they may be significantly compressed and deformed, reducing their volume, thus allowing the fiber web to make close contact with the surface of the blank. For insulating glass microspheres, they will be crushed when their critical crushing strength is reached. Whether compressed or crushed, their original space will be quickly filled by the adhesive, which now has good flowability. The entire composite interface reaches a dense state under high pressure. Therefore, these "temporary" venting channels can be effectively crushed or filled after fulfilling their purpose, without leaving a permanent void.

[0036] In some embodiments of the present invention, the microspheres include polymer elastic microspheres and / or hollow glass microspheres. The microspheres are bonded to the side of the fiber mesh used for bonding with the plate blank by mixing with an adhesive. The diameter of the microspheres is 10~135μm. Short fibers are vertically implanted into the fiber web via electrostatic action on one side for composite with the board blank. The length of the short fibers is 200μm~5mm.

[0037] In some embodiments of the present invention, the process parameters for continuous flattening processing are as follows: The pressure setting value of the press inlet zone of the continuous flat press is 20-30% of the maximum pressure value, and the temperature value is 120-150℃. The time of the plate blank in the inlet zone accounts for 20-30% of the total time. After the sheet blank enters the middle zone of the continuous flat press, it is first pressurized to 50-60% of the maximum pressure value, then instantly reduced to 10-20% of the maximum pressure value, and then gradually increased to 70-80% of the maximum pressure value. The temperature in the middle zone is set to 160-280℃. The sheet blank spends 50-60% of the total time in the middle zone. The time ratio of the three pressure stages in the middle zone is (65-70):(5-15):(20-25). After the sheet blank enters the exit zone, the pressure is increased to 100% of the maximum pressure value, and the temperature drops by 0~20℃ compared to the middle zone. The sheet blank spends 20~30% of the total time in the exit zone.

[0038] The maximum pressure value is 1~8MPa.

[0039] In this embodiment, the inlet zone is used for preheating, microchannel establishment, and initial venting. A low pressure is applied during this stage, sufficient to allow initial contact between the preform, fiber web, and microspheres, but not enough to instantly crush the microspheres or block their established venting channels. This low-pressure environment provides the initial impetus for the escape of water vapor and volatiles from within the preform, initiating venting through the microchannels. This temperature is designed to preheat the fiberboard and ensure that the adhesive (if thermosetting) is fully melted and has good fluidity to begin wetting the fiber web and preform surface. The temperature at this stage must not be too high to prevent premature gelation of the adhesive, which could block the functioning venting microchannels.

[0040] The middle section is used for core venting, adhesive pre-curing, and interface compaction. The pressure is gradually increased from the level of the inlet section to a medium pressure to promote further adhesive wetting and interface contact. Then, a significant pressure reduction window is set at a critical point where the adhesive is about to gel but not yet fully cured. This "pressure reduction window" is the golden period for venting; gas accumulated inside the slab will escape rapidly through microchannels, effectively preventing gas blockage and delamination. After a brief pressure reduction, the pressure should be steadily increased to a higher pressure to compact the composite structure, which may have slightly loosened due to venting, ensuring tight interface contact. The temperature at this stage significantly accelerates the cross-linking reaction of the adhesive. At the end of this stage, the adhesive reaches a gel state, and the interface has sufficient initial strength to withstand subsequent higher pressures without being damaged.

[0041] The exit zone is used for final curing, thickness setting, and stabilization. This stage applies the highest pressure to ensure the board reaches the preset final thickness and achieves molecular-level tight contact at the composite interface, resulting in maximum composite strength. At this point, most microspheres should be compressed or crushed under this high pressure, their spaces filled by the flowing adhesive, and the interface tends to densify. Sufficient heat is required at this stage to ensure the adhesive fully cures. For fiberboard blanks (e.g., stone fiber) themselves, this temperature also ensures the complete curing of any organic binders within them. Furthermore, appropriate cooling helps reduce internal stress when the board exits the press, improving dimensional stability.

[0042] It should be noted that the dwell time in each zone can be controlled by the speed, and the total process time can be determined based on the thickness of the sheet material.

[0043] Please refer to Figure 2 In some embodiments of the present invention, the fiber web output device includes a fiber spool and a curved feeder. The fiber spool is used to hold the wound fiber web. The fiber web enters one end of the curved space of the curved feeder through the strip-shaped outlet of the fiber spool. The curved space is part of a cylindrical surface. The fiber web exits from the opening at the other end of the curved space. A pressure roller is provided at one end of the curved space by a spring. The pressure roller and the opening at one end of the curved space clamp the fiber web.

[0044] In this embodiment, the fiber web output from the fiber tube enters a narrow curved space. The thickness of the curved space is 1.1 to 1.2 times the thickness of the fiber web, maintaining the planar distribution of the fiber web. At the same time, the fibers exiting the curved space are pressed by the pressure roller, so that the fiber web matches the shape of the curved space and is also distributed in a curved manner. This gives the fiber web a certain tension, preventing it from wrinkling. When the board blank with adhesive at the bottom passes through the pressure roller, the fiber web is laid flat on the board blank by the rolling pressure roller and has a certain tension, which facilitates the subsequent pre-curing process.

[0045] It should be noted that the linear speed of the pressure roller is the same as the speed of the sheet blank, which facilitates the flat laying of the fiber web on the sheet blank. After the fiber web is laid flat, the portion of the fiber web exposed in the curved space can be cut off to allow for the fiber web laying of the next sheet blank.

[0046] Please refer to Figure 2In some embodiments of the present invention, the fiber output device is divided into an upper fiber output device and a lower fiber output device. Each fiber roller output device includes a fiber roller and a feeder. The fiber roller is fitted with a rolled fiber web and is equipped with a tensioning and braking device (not shown in the figure) to ensure that the fiber web is output uniformly with the speed of the board blank. After being output by the fiber roller, the fiber web enters the feeder, which includes a pressure roller and a cutting device. The pressure roller is in close contact with the conveyor belt of the laying section or the upper surface of the board blank. The linear speed of the pressure roller is the same as the speed of the board blank, which facilitates the fiber web to be laid flat on the board blank. The cutting device is a blade (such as 1-3) that slides automatically along the pressure roller and is used to cut the fiber web.

[0047] Please refer to Figure 3 In some embodiments of the present invention, the spraying device uses high-pressure air supply to atomize the acrylic paint through nozzles and spray it evenly onto the slab. It includes a high-pressure air source tank 8-1, an acrylic paint tank 8-2, a support, and nozzles 8-3.

[0048] This invention provides a composite fiberboard prepared according to any of the above-described preparation methods.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite fiber density board, characterized in that, include: In the continuous flat roller paving section, fiber material mixed with binder is paved. The binder includes powder or liquid binder, and the fiber material includes organic or inorganic fibers, or a mixture of both. Equipped with a fiber web output device, the fiber web is covered on the upper and lower surfaces or any one side of the sheet blank. The fiber web is woven from glass fiber or carbon fiber and is treated with a coupling agent to improve the interfacial bonding properties. Equipped with a spraying device, a layer of water-based acrylic coating is sprayed onto the surface of the laid slab to improve the surface density of the slab and increase its strength. The composite board blank composed of the fiber web and fiber material enters the hot pressing section of the continuous flat press. Under high temperature and high pressure, the fiber web and fiber material are combined into one piece under the action of the binder, high temperature and high pressure to obtain a composite fiber density board with a high-strength fiber web on the surface. After covering the upper and lower surfaces or any one side of the sheet blank with a fiber mesh, before spraying water-based acrylic, the process further includes: The fiber mesh-bonded plate blank is pre-cured using the upper and lower pressure plates of a hot pressing device; wherein, a deformable plate is provided on the pressing surface of the upper and lower pressure plates; The deformable plate includes a deformable plate made of shape memory polymer. The glass transition temperature of the deformable plate is lower than the curing temperature but higher than the room temperature. The pre-curing treatment includes room temperature flat pressing and high temperature curing in sequence. Thermally conductive fillers are added to the shape memory polymer. The ambient temperature pressure adjustment includes applying pressure at 0.2 MPa for 30 seconds; The high-temperature curing process includes raising the temperature gradient to 120°C and holding it at that temperature for 8 minutes, wherein the heating rate is 10°C / min, and the pressure is increased to 0.8MPa during the heating process, wherein the pressure gradient is 0.078MPa / min. The upper pressure plate and the lower pressure plate each have a release layer on their deformable plates, the release layer comprising a PET film substrate core solid silicone coating layer; The fiber web is pre-coated with microspheres and / or short fibers at intervals; The high-temperature and high-pressure process parameters are as follows: The pressure setting value of the press inlet zone of the continuous flat press is 20-30% of the maximum pressure value, and the temperature value is 120-150℃. The time of the plate blank in the inlet zone accounts for 20-30% of the total time. After the sheet blank enters the middle zone of the continuous flat press, it is first pressurized to 50-60% of the maximum pressure value, then instantly reduced to 10-20% of the maximum pressure value, and then gradually increased to 70-80% of the maximum pressure value. The temperature in the middle zone is set to 160-280℃. The sheet blank spends 50-60% of the total time in the middle zone. The time ratio of the three pressure stages in the middle zone is (65-70):(5-15):(20-25). After the sheet blank enters the exit zone, the pressure increases to 100% of the maximum pressure value, and the temperature drops by 0~20℃ compared to the middle zone. The sheet blank spends 20~30% of the total time in the exit zone. The maximum pressure value is 1~8MPa.

2. The preparation method according to claim 1, characterized in that, The fiber material has a fiber diameter of 0.5-10 micrometers and a length of 1-10 micrometers; the binder to fiber weight ratio is 5%-18%.

3. The preparation method according to claim 1, characterized in that, The mesh size of the fiber web ranges from 0.1mm x 0.1mm to 10mm x 10mm.

4. The preparation method according to claim 1, characterized in that, The spraying device uses an air atomizer with a pressure of 0.3-1.0 MPa and a paint spraying rate of 30-200 g / m³. 2 .

5. The preparation method according to claim 1, characterized in that, The fiber web output device includes a fiber spool and a curved feeder. The fiber spool is used to hold the wound fiber web. The fiber web enters one end of the curved space of the curved feeder through the strip-shaped outlet of the fiber spool. The curved space is part of a cylindrical surface. The fiber web exits from the opening at the other end of the curved space. A pressure roller is provided at one end of the curved space by a spring. The pressure roller and the opening at one end of the curved space clamp the fiber web.

6. The preparation method according to claim 1, characterized in that, The microspheres include polymer elastic microspheres and / or hollow glass microspheres. The microspheres are bonded to the fiber mesh on the side for bonding with the plate blank by mixing with an adhesive. The diameter of the microspheres is 10~135μm. The short fibers are vertically implanted into the fiber web by electrostatic action on one side for composite with the board blank, and the length of the short fibers is 200μm~5mm.

7. A composite fiber density board, characterized in that, Prepared by the preparation method according to any one of claims 1-6.

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