JP7752437B2 - Manufacturing process of compacted board to length based on high frequency - Google Patents

Description

The present invention belongs to the field of wood board processing technology, and specifically relates to high-frequency-based, standard-length compacted boards.

The medium density fiberboard, particle board, multi-layer board, and log board used in board-type furniture are basically standard-sized board materials, for example, 48 shaku (length and width dimensions are 1220 mm x 2440 mm) and 49 shaku (length and width dimensions are 1220 mm x 2745 mm). However, the related art does not disclose standard-sized compressed wood used in the customized furniture industry. CN111347511 A (2020.06.30) describes a method for manufacturing adhesive-free composite materials based on high-frequency mixed materials, in which at least two wood boards with a density not exceeding 0.7 kg/ ^m3 are heated and pressed by high frequency to form a degraded joint layer between two adjacent wood boards. The manufacturing method specifically includes the steps of pre-treatment, lamination, heating and pressing, hardening, cooling, and curing. However, this patent does not manufacture horizontally joined compacted boards, but multi-layer compacted boards, and manufacturing standard-sized boards is difficult and costly to mass-produce. CN112847694 A (May 28, 2021) discloses an adhesive-free horizontal joining and consolidation device (see FIG. 1, where 1 is a lower pressure plate, 2 is an upper pressure plate, 4 is a lower backing plate, 5 is an upper backing plate, 6 is a hydraulic rod, and 30 is a horizontal joining plate) and an adhesive-free horizontal joining and consolidation method, which includes the steps of: (1) arranging several horizontal joining plates in a plane in order, sandwiching a resin film between two adjacent horizontal joining plates, and making the contact surfaces of the two adjacent horizontal joining plates form an angle of 45-135° with the plane; The method includes the steps of: (2) applying a first biasing force F1 in the horizontal direction of the array plate, where F1 is 1.5-2 MPa; (3) heating the array plate to 60-170°C, applying a second biasing force F2 in the vertical direction of the array plate, where F2 is 0.7 MPa or more, and maintaining the pressure for 8-10 minutes; and (4) increasing F1 to F3 while maintaining F2, where F3 is 2.5-4 MPa, and maintaining the pressure until the temperature of the array plate reaches 40-70°C. This patent uses heating during the molding process to produce a horizontally bonded consolidated plate, but producing standard-sized plate materials is still difficult to mass-produce and expensive.

In view of at least the above technical problem, several embodiments of the present invention provide a high frequency based process for manufacturing a compacted board to length, the process comprising:
a first preheating step in which several cork slabs with a moisture content of 10% to 20% are irradiated with infrared light to raise the average temperature to 80 to 90°C, thereby obtaining several preheated cork slabs;
a water layer deposition step of depositing a water layer on the surface of the preheated cork slab irradiated with infrared light to obtain several water layer-deposited cork slabs;
a high-frequency hot pressing step in which the water-layer-attached cork boards are subjected to a heat compression treatment and hardening treatment under high-frequency conditions to obtain several compacted wood boards;
A cooling step in which some of the compressed wood boards are cooled to an average wood temperature of 70 to 90°C or room temperature;
a longitudinal joining step of joining longitudinally adjacent cooled compacted wood board strips to obtain several longitudinally joined compacted wood boards;
a horizontal joining step of joining adjacent longitudinally joined compacted wood boards in the width direction to obtain several horizontally joined compacted wood boards;
and a sizing step of cutting several transversely bonded compacted wood boards to size into several compacted boards.

In the manufacturing process, the water layer-attached cork strips are further subjected to the high-frequency hot pressing step through a second preheating step, during which:
In the second preheating step, several water-layered cork strips are irradiated with infrared light to maintain an average temperature of 80-90°C.

Furthermore, in the manufacturing process, in the first preheating step and/or the second preheating step, infrared irradiation is carried out in an infrared irradiation space, and the temperature of the infrared irradiation space is 130 to 150°C.

Furthermore, in the manufacturing process, water is applied or sprayed onto the surface of the preheated cork strip one to four times during the water layer deposition step.

Furthermore, in the manufacturing process, in the vertical joining step, the vertical joining contact surfaces of adjacent longitudinally adjacent compacted wood board strips of each vertically joined compacted wood board are curved or inclined, and the inclined surfaces include inclined flat surfaces or inclined curved surfaces, and preferably, the curved surfaces or inclined curved surfaces are sawtooth surfaces.

Furthermore, in the manufacturing process, in the lateral joining step, the lateral joining contact surfaces of adjacent densified wood board strips in the width direction of each lateral-joined densified wood board are flat or inclined, and the inclined surfaces include inclined flat surfaces or inclined curved surfaces, and preferably, the inclined curved surfaces are sawtooth surfaces.

Furthermore, in the manufacturing process, adjacent longitudinally joined contact surfaces or adjacent transversely joined contact surfaces are both connected by a resin layer, and the resin layer may be one or more of a PVA resin layer, a PVB resin layer, or a PVC resin layer, but is not limited to these. The resin used for the resin layer may be a mixture of one or more of an ethylene-vinyl acetate copolymer or a polyolefin-based material, and the polyolefin-based material may be a mixture of one or at least two of polyethylene, polypropylene, modified polyethylene, modified polypropylene, or an ethylene-based elastomer containing ethylene units.

Furthermore, in the manufacturing process, the step of forming the resin layer is as follows.
In S1, the joint end surface of the compacted wood board is processed into a curved surface or an inclined surface, and the inclined surface includes an inclined plane or an inclined curved surface, and preferably, the curved surface or the inclined curved surface is a sawtooth surface;
In S2, the resin is hot-melted to produce a hot-melt resin, and the hot-melt resin is applied to the joining end surface of the compacted wooden board;
In S3, the joining end faces of the adjacent compacted wooden boards are pressed with a first biasing force.

Furthermore, in step S2 of the manufacturing process, after the resin is hot-melted, 20-40 mesh resin particles are added and mixed uniformly to obtain a hot-melt resin paste, which is then applied to the end surface of the compacted wood to a fixed length, with the weight ratio of the resin to the resin particles being 8:1-12:1, and the resin particles may include, but are not limited to, one or more of PVA particles, PVB particles, and PVC particles.

Furthermore, in the manufacturing process, a cooling treatment step involves using liquid nitrogen freezing technology to cool some of the compacted wood boards to room temperature in an environment of -150°C to -130°C for 9 to 15 minutes, and then joining them vertically.

The beneficial effects of the present invention are as follows: The high-frequency-based, fixed-length compacted plate of the present invention has good processing performance such as good screw gripping force, bending strength, and bending elasticity, as well as excellent resistance to accelerated aging, and its manufacturing method is easy to mass-produce and low cost.

1 is a prior art horizontal joint consolidation device. This is a fixed-length compaction plate according to an embodiment of the present invention. This is a vertically joined, compacted wood board according to an embodiment of the present invention. FIG. 1 is a schematic diagram of a transverse joint. This is a fixed-length compaction plate according to an embodiment of the present invention. FIG. 1 is a side view of a fixed-length compaction plate according to an embodiment of the present invention.

The following examples further illustrate the present invention but should not be construed as limitations thereon. Any modifications or substitutions made to the methods, steps, or conditions of the present invention that do not depart from the spirit and substance of the present invention are within the scope of the present invention.

(Interpretation of terms)
Standard lengths refer to the manufacture of plates with lengths and widths specified by product standards, and as will be appreciated, standard length plates are more suitable for robotic and pipeline operations, and can be mass-produced to reduce costs.

Single pressing means that the hot press machine hot presses one layer of wood board.

Combined pressing refers to the hot pressing of multiple layers of wood boards using a hot press machine. For example, when a hot press machine hot presses three layers of wood boards, it is called "three-combined pressing."

Vertical joints, also known as longitudinal joints or straight joints, are the joining of adjacent wooden boards in the longitudinal direction.

A horizontal joint, also known as a horizontal joint or fixed-length lateral joint, is the joining of adjacent wooden boards in the width direction, as shown in Figure 4.

Referring to the joint end surface as shown in Figure 4, the end surface of the wooden board includes six surfaces, and joint end surface 9 is one end surface for joining the wooden boards. After joining, the joint end surface is also called the vertical joint contact surface or the horizontal joint contact surface.

Referring to the resin layer as shown in Figure 4, resin layer 8 is located between the joining end surfaces 9.

The first biasing force is a first biasing force F1 applied in the horizontal direction, which can be realized, for example, by an air compaction device, see Chinese Patent Application No. CN112847694 A.

The second biasing force is a second biasing force F2 applied in the vertical direction, which can be achieved, for example, using a high-frequency hot press, as described in Chinese Patent Application No. CN112847694 A. The uses of the compacted board of the present invention are not specifically limited, and in addition to producing the base material for board-type furniture, it can also be used as a flooring base material, i.e., the base material for decoratively finished artificial boards.

Optional equipment used in embodiments of the present invention includes, but is not limited to, slicers, infrared preheating equipment, water layer deposition equipment (which may be a coating or spray equipment), high-frequency hot presses, liquid nitrogen freezing equipment, square groove processing machines, sorting systems, tooth driving equipment, roll coaters, air compaction equipment (including hydraulic press-based clamping devices for various board pipelines), woodworking breakers, and wood board printing machines. Optional references include Chinese Patent Application No. CN201811592197 - High-frequency adhesive-free compaction equipment, Chinese Patent Application No. CN201910181348 - High-frequency compacted wood combination production line, Chinese Patent Application No. CN201922120903 - Adhesive-free horizontal joint compaction equipment, and Chinese Patent Application No. CN202010100409 - Equipment for uniformly discharging compressed water vapor from the surface of compacted wood and compacted wood pipeline equipment. Equipment or production lines reconstructed based on the concept of the present invention are also within the scope of protection of the present invention.

Optional infrared preheating equipment in an embodiment of the present invention is several infrared preheating boxes that can be installed on a conveying device (which may be a conveying chain or rollers) of a production line. That is, the conveying device can carry the plate material and pass through several infrared preheating boxes from below inside the box. Each infrared preheating box includes an infrared heating preheating tube installed at the top inside the box. The wattage of the infrared heating preheating tube is adjustable, allowing the space temperature in the infrared preheating box to be constantly maintained at around 150°C. The length of the infrared preheating box on the production line can be set according to process requirements. When the length of the infrared preheating box on the production line is predetermined, the speed of the conveying device (e.g., a conveying chain) can be further adjusted to achieve a preheating temperature of the plate material between 60°C and 100°C. For example, the speed rate is slow when the preheating temperature is 100°C, and the speed is fast when the preheating temperature is 60°C.

In an embodiment of the present invention, an optional water layer application device is several water layer applicators that can be installed on a conveying device (which may be a conveying chain or rollers) of the production line. That is, the conveying device can carry the board material and pass through the interior of several applicators from below. Each water layer applicator includes a group of application rollers (including one drive roller and one driven roller) installed inside the box, and a water supply device. The water supply device can spray water onto the group of application rollers, which can then apply water to the wooden board and further adhere the water layer to the wooden board. The number of water layer applicators or the number of roller groups can be configured according to process requirements. For example, each water layer applicator can be equipped with one group of application rollers, or each water layer applicator can be equipped with two groups of application rollers. Obviously, if two applications are required, two of the former and one of the latter are required. The application speed (the rotational speed of the roller group) usually always matches the running speed of the conveying device.

Optional liquid nitrogen freezing equipment in an embodiment of the present invention is several liquid nitrogen freezing boxes that can be installed on a conveying device (which may be a conveying chain or roller) of a production line, i.e., the conveying device can carry the plate material and pass through the interior of several liquid nitrogen freezing boxes from below. The temperature inside the liquid nitrogen freezing boxes is approximately -150°C to -130°C.

The corresponding designs of the above-mentioned infrared preheating box, liquid nitrogen freezing equipment, and water layer coating machine, including their mechanical and electrical structures, can be realized using known technologies and will not be described in detail in this application.

The present invention will be described below with reference to the embodiments. All of the methods cited in the Chinese patent applications are full citations. Those skilled in the art can make direct citations or indirect citations with minor modifications based on the concept of the present invention. The present invention does not specifically limit the citation method.

(Embodiment 1) Manufacturing of Cork Strips The cork strips used in the examples of the present invention can be manufactured using any known technology, such as a sawing method and a slicing method that controls the moisture content to 60-80% (using a slicing method instead of a sawing method; poplar, which has a high moisture content, is more suitable for slicing, does not require pre-treatment drying, and reduces substrate loss), or a steaming and slicing method (including the steps of selecting material, steaming, slicing, and air-drying). The dimensions of the cork strips used in the examples of the present invention are determined based on the dimensions of the standard compacted board. For example, a standard compacted board measuring 48 feet (4 feet x 8 feet) is manufactured. The cork strips can be 1-4 cm thick and 22 cm or 44 cm wide, and the cork is generally poplar. The moisture content of the cork strips is generally 10%-20%.

(Embodiment 2) Manufacturing of Cork Strips with a Water Layer In some embodiments of the present invention, the water layer is applied two to four times using the water layer coater to coat the surface of the preheated cork strips irradiated with infrared light, thereby obtaining several cork strips with a water layer attached. The water layer coater is easily installed in a pipeline, but in an optional embodiment, a spray device can be used to coat the surface of the preheated cork strips. Of course, for small-scale production, a thin water layer can be manually applied to the surface of the preheated cork strips. The water layer-attached cork strips generate hot steam during high-frequency hot pressing, which further changes the wood texture of the resulting compacted wood boards (reducing hairlines). Other implementations based on the concept of the present invention are also within the scope of protection of the present invention.

(Embodiment 3) Manufacturing of Densified Wood Boards (Single Pressed) The manufacturing method of the densified wood boards (single pressed) used in the embodiments of the present invention includes at least the steps of heat compression treatment and hardening treatment, and optional embodiments include cooling treatment and curing treatment. The method hereinafter is based on Chinese Patent Application CN109465932A, and optional manufacturing methods of the densified wood boards (single pressed) in the embodiments of the present invention are as follows:

In the heat compression process, the wood is heated using high frequency waves until the average temperature of the wood reaches 100-110°C, kept at that temperature for 5-7 minutes, and then compressed at the first compression ratio.

During the hardening process, the heat-compressed wood is heated using high-frequency waves until the average temperature of the wood reaches 180-220°C, and then the temperature is maintained for 5-8 minutes to complete the hardening process.

During the cooling process, the hardened wood surface is cooled using water cooling technology at a rate of 5-15°C/min until the average temperature of the wood reaches 70-90°C. The water flow rate for water cooling is 0.9-1.3 m/s. Once the wood surface temperature reaches 85-90°C during the cooling process, wind cooling is performed at a wind speed of 9.2-9.7 m/s and a wind temperature of 55-60°C.

During the curing process, the cooled wood is placed at room temperature and cured for 13-15 days to obtain adhesive-free, compacted hardwood. The specific curing method is to place the cooled wood on a horizontal drying surface, apply a pressure of 5.5-7.2 MPa to the top surface of the wood, and after curing for three days, reduce the pressure by 1.2-1.5 MPa each day until the pressure reaches zero, and continue curing for 10-12 days.

(Embodiment 4) Manufacturing of Densified Wood Boards (San He Zhi) The manufacturing method of densified wood boards (San He Zhi) used in the embodiments of the present invention includes at least the steps of hot compression treatment (also called hot pressing treatment) and hardening treatment, and optional embodiments include cooling treatment (also called temperature reduction treatment) and curing treatment. The method hereinafter is based on Chinese Patent Application CN111347511A, and optional manufacturing methods of densified wood boards (San He Zhi) in the embodiments of the present invention are as follows:

In the lamination process, two or more wooden boards are stacked and placed based on at least one force-receiving direction to obtain a laminated wooden board, where the force-receiving direction includes a direct pressure direction and an indirect pressure direction.

In the heat and pressure treatment, the deteriorated connection layer of the laminated wood board is heated until the board temperature reaches 80-100°C, kept at that temperature for 4-6 minutes, and then pressure treatment is performed at a compression rate preset based on the direction of the applied force.

In the hardening process, the heated and pressurized wood board is heated using high frequency waves until the board temperature reaches 180-220°C, and then kept at that temperature for 5-8 minutes to harden it, producing a hardened wood board.

During the temperature reduction process, the hardened wood board surface is cooled using water cooling technology at a rate of 5-15°C/min until the wood board temperature reaches 70-90°C. The water flow rate for water cooling technology is 0.9-1.5 m/s, and the wood board surface temperature is cooled to 85-90°C. Air cooling is then performed at an air speed of 9.2-9.7 m/s and an air temperature of 55-60°C.

During the curing process, the cooled wood board is left at room temperature for 15-20 days to obtain an adhesive-free composite material based on the high-frequency mixture.

The standard-length compressed boards manufactured based on the triple-compression method have a three-layer design in the thickness direction and two seams in the width direction, allowing the horizontal and vertical stresses of adjacent laminated boards to interact and offset each other, demonstrating the anti-rebound performance of the structure. In addition, since the wood properties of different slices are inevitably different, the standard-length compressed boards have unique creases (corresponding to anti-counterfeit creases) on the sides after hot pressing, which are similar to natural wood and a characteristic not found in other products such as particle boards.

(Embodiment 5) Manufacturing of Vertically Jointed Densified Wood Boards The manufacturing method of vertically joined densified wood boards used in the examples of the present invention includes, but is not limited to, the method of Chinese Patent Application No. CN201911193101, which requires sandwiching a resin film between wood boards and then hot pressing. In addition, some examples of the present invention use the following resin-mixed material sandwiching method.

Adjacent cooled compacted wood board strips are joined in the longitudinal direction to obtain several vertically joined compacted wood boards, and specifically include the following steps:

a) Mixing the materials, heating and hot-melting the resin to obtain a resin hot-melt material, then adding 20-40 mesh resin particles and stirring to obtain a resin mixed material (also called a paste-like hot-melt resin), the resin including, but not limited to, one or more of PVA, PVB, and PVC, and the resin particles including, but not limited to, one or more of PVA particles, PVB particles, and PVC particles.

b) Finger joint (compacted pipeline) is made by sawing the two end faces of a three-joint pressure plate cut to a specified length to obtain a finger jointed three-joint plate.

c) Using a roller machine, resin is applied to the comb tooth portion of the comb tooth tri-board. In the pipeline, the comb tooth tri-boards with resin applied are brought into contact at the head and tail. The comb tooth portions of the two front and rear comb tooth tri-boards are pressurized while operating in the pipeline's air compression device, and the comb tooth-connected tri-board is transferred to a fixed-length direct pressure air compression device.

d) In fixed-length direct compression, the plywood with the connected comb teeth is placed in a fixed-length direct pressure air compaction device and compressed to obtain a fixed-length direct pressure compacted board.

(Embodiment 6) Manufacturing of Horizontally Jointed Densified Wood Boards The manufacturing method of vertically joined densified wood boards used in the examples of the present invention includes, but is not limited to, the method of Chinese Patent Application No. CN201911193101, which requires sandwiching a resin film between wood boards and then hot pressing. In addition, some examples of the present invention use the following resin hot melt material sandwiching method.

a) The resin is heated and hot-melted to obtain a resin hot-melt material.

b) A resin hot melt material is applied between adjacent widthwise joined, vertically joined, compacted wooden boards, followed by a pressure applied using an air compacting device. The joining is then completed using a fixed-length side pressure air compacting device, resulting in several horizontally joined, compacted wooden boards (also called fixed-length side pressure compacted boards).

(Embodiment 7) Manufacturing of fixed-length compressed boards As shown in Figures 2 and 3, the fixed-length compressed board 1 of the present invention comprises several vertically joined compressed wood boards 2 of the same dimensions pressed together in the width direction, each vertically joined compressed wood board 2 comprising several compressed wood board strips 3 pressed together in the length direction, and each compressed wood board strip 3 comprising several cork strips 4 pressed together in the thickness direction by a high-frequency hot pressing step.

A vertical joint pattern 5 is formed at the joints of adjacent compacted wood board strips 3, a horizontal joint pattern 6 is formed at the joints of adjacent vertically joined compacted wood boards, and multiple high-frequency hot-press patterns 7 are formed at the joints of adjacent cork strips.

The vertical joint patterns 5 of adjacent vertically joined compacted wood boards 2 are not in the same straight line.

The high-frequency hot-pressed patterns 7 on adjacent cork strips 4 are oriented in the same direction but do not intersect. Specifically, because the high-frequency hot-pressed patterns 7 are formed by high-frequency pressure molding, the wood properties of different cork strips 4 are inevitably different. As a result, unique creases (corresponding to anti-counterfeiting creases) are formed on the sides of the standard-length compacted board after hot pressing, as shown in Figure 2.

Among the several vertically joined compacted wooden boards 2 of each fixed-length compacted board 1, the one located in the middle is a vertically joined compacted wooden board 2 of the same size,
The widths of the several compacted wood board strips 3 of each vertically joined compacted wood board 2 are equal.

The standard-length compacted board of the present invention has a density of 0.58 to 0.6, strength equivalent to that of pine wood, and can be used as a cabinet board instead of particle board, multilayer board, and density board. Its performance includes a board surface screw grip strength of 1400 N to 1600 N, a bending strength of 50 MPa to 65 MPa, and a bending elasticity of 6500 MPa to 7500 MPa.

The manufacturing process for the fixed-length compacted board is as follows:
a first preheating step of irradiating several cork strips with a moisture content of 10%-20% with infrared light to raise the temperature to an average temperature of 80-90°C to obtain several preheated cork strips;
a water layer adhering step of adhering a water layer to the surface of the preheated cork strip irradiated with infrared light to obtain several water layer-adhered cork strips;
a high-frequency hot pressing step in which the water layer-attached cork strips are subjected to a heat compression treatment and hardening treatment according to the method of Example 2 or Example 3 under high-frequency conditions to obtain several compacted wood boards;
a cooling step of cooling some of the compressed wood boards according to the method of Example 2 or Example 3 until the average temperature of the wood reaches 70-90°C;
a longitudinal joining step of joining longitudinally adjacent cooled compacted wood board strips to obtain several longitudinally joined compacted wood boards;
A horizontal joining step of joining adjacent vertically joined compacted wood boards in the width direction to obtain several horizontally joined compacted wood boards, as shown in FIG.
and a sizing step of cutting several horizontally joined compacted wood boards into several standard-length compacted boards using a woodworking breaker.

Some embodiments of the present invention can improve the screw grip strength of standard-length compacted boards by at least 30%. Taking poplar as an example, its density reaches 0.58-0.6, and its strength is equivalent to that of pine. It can replace particle board, multi-layer board, and density board, and can be used as cabinet board.

(Embodiment 8) Manufacturing of decoratively finished artificial boards In some alternative embodiments, the standard compacted board is used as a substrate for decoratively finished artificial boards,
The method further includes a pattern printing step in which several standard-sized compacted boards are rubbed and a pattern (printing layer) is printed on a wood-printing machine to obtain several decoratively finished artificial boards.

The present invention will be further explained below with reference to specific examples and comparative examples.

(Example 1) Production of standard-sized compacted boards 1. In the cork strip production step, referring to the method of embodiment 1, standard-sized poplar boards (also known as cork strips) with a length of 50 cm-120 cm and a width of 22 cm were produced, with a moisture content of 15±3%.

2. In the first preheating step, several cork strips with a moisture content of 15±3% are irradiated with infrared light in the infrared preheating box until the average temperature reaches 80-90°C. The temperature in the infrared irradiation space is 130°C, and several preheated cork strips are obtained.

3. In the water layer attachment step, referring to embodiment 3, two water layer applicators each equipped with a set of application rollers are used to apply the water layer twice in total, attaching the water layer to the surface of the preheated cork strips irradiated with infrared light, thereby obtaining several cork strips with the water layer attached.

4. In the high-frequency hot pressing step, the water-layer-attached cork strips are subjected to a heat-compression and hardening treatment under high-frequency conditions based on the method of embodiment 3 to obtain several compacted wood boards.

5. In the cooling treatment step, several compacted wood boards are cooled according to the method of embodiment 3 until the average temperature of the wood reaches 70-90°C.

6. In the longitudinal joining step, referring to the method of Chinese Patent Application No. CN201911193101, adjacent cooled compacted wood board strips are joined in the longitudinal direction to obtain several vertically joined compacted wood boards.

7. In the horizontal joining step, adjacent vertically joined compacted wood boards in the width direction are joined together to obtain several horizontally joined compacted wood boards, referring to the method described in Chinese Patent Application No. CN201911193101.

8. In the sizing step, several horizontally joined compressed wood boards are cut to several standard-length compressed boards using a woodworking breaker to obtain 48-foot (4 feet x 8 feet) standard-length compressed boards (length, width, and thickness dimensions are 2440 mm x 1220 mm x 20 mm).

(Example 2) Manufacturing of fixed-length compacted plates This is basically the same as Example 1, but differs as follows.
In the first preheating step, the temperature of the infrared irradiated space is 140°C.
In the water layer application step, three water layer coaters each having one group of coating rollers are used to coat the water layer a total of three times.

(Example 3) Manufacturing of fixed-length compacted plates This is basically the same as Example 1, but differs as follows.
In the first preheating step, the temperature of the infrared irradiated space is 150°C.
In the water layer application step, three water layer coaters each having one group of coating rollers are used to coat the water layer a total of three times.

The water layer-attached cork strip is subjected to the high-frequency hot pressing step after the second preheating step, during which:
In the second preheating step, several water-layered cork strips are irradiated with infrared light and maintained at an average temperature of 80-90°C.

(Example 4) Manufacturing of fixed-length compacted plates This is basically the same as Example 1, but differs as follows.
In the vertical joining step, referring to the resin kneading material clamping method of embodiment 5, adjacent cooled compacted wood boards in the longitudinal direction are joined to obtain several vertically joined compacted wood boards, among which the vertical joining contact surfaces of the compacted wood boards adjacent in the longitudinal direction of each vertically joined compacted wood board are sawtooth surfaces.
In the horizontal joining step, referring to the resin hot melt material clamping method of embodiment 6, adjacent vertically joined compacted wood boards in the width direction are joined to obtain several horizontally joined compacted wood boards, among which the horizontally joined contact surfaces of the adjacent compacted wood boards in the width direction of each horizontally joined compacted wood board are flat.

Two adjacent vertical joint contact surfaces or two adjacent horizontal joint contact surfaces are both pressed together by a PVB resin layer.

The steps for forming the vertically bonded PVB resin layer are as follows.
In S1, the joint end surface of the compacted wooden board is processed and formed into a sawtooth surface,
In step S2, the PVB resin is hot-melted, and then 20-40 mesh PVB resin particles are added and stirred to obtain a PVB resin kneaded material. The PVB resin kneaded material is applied to the joint end surface (vertical joint contact surface) of the standard-length compacted lumber, and the weight ratio of the PVB resin to the PVB resin particles is 8:1.
In S3, the joint end faces of adjacent compacted wooden boards are pushed out by an air compaction device.

The steps for forming the PVB resin layer for horizontal bonding are as follows.
In S1, the joint end surface of the compacted wooden board is processed and shaped into a flat surface (if it is already flat, this step is omitted),
In S2, the PVB resin is hot-melted to obtain a PVB resin hot-melt material, and the PVB resin kneaded material is applied to the joint end surface (lateral joint contact surface) with the standard-length compacted wood;
In S3, the joint end faces of adjacent compacted wooden boards are pushed out by an air compaction device.

(Example 5) Manufacturing of fixed-length compacted plate This is basically the same as Example 4, but differs as follows.
In the step of forming a vertical joining contact surface,
In S1, the joint end surface of the compacted wooden board is processed and formed into a sawtooth surface,
In S2, the weight ratio of PVB resin to PVB resin particles is 10:1.
In the step of forming a lateral joining interface,
In S1, the joint end surfaces of the compacted wooden boards are processed and shaped into an inclined plane.

(Example 6) Manufacturing of fixed-length compacted plate This is basically the same as Example 4, but differs as follows.
In the step of forming a vertical joining contact surface,
In S1, the joint end surface of the compacted wooden board is processed and formed into a sawtooth surface,
In S2, the weight ratio of PVB resin to PVB resin particles is 12:1;
In the step of forming a lateral joining interface,
In S1, the joint end surfaces of the compacted wooden boards are processed and shaped into a flat surface.

(Example 7) Manufacturing of fixed-length compacted plate This is basically the same as Example 4, but differs as follows.
In the high-frequency hot pressing step (three-combined pressing), the water layer-attached cork strip is subjected to a heat compression and hardening treatment under high-frequency conditions in accordance with the method of embodiment 4 to obtain a three-combined pressed board with burrs, and a square groove processing machine is used to trim the front, back, left and right sides of the three-combined pressed board with burrs to obtain several compacted wood boards (also called three-combined pressed boards).
In the lamination process, three water-coated cork strips are stacked in one direction to form a laminated wood board, and then six to eight laminated wood boards are arranged on the compaction plate/pallet of the hot press machine according to a matrix, with the direction of the force being the direct pressure direction.

The high-frequency conditions are a compression speed of 25 seconds per cycle and a compression ratio of 25%.

(Example 8) Manufacturing of fixed-length compacted plate This is basically the same as Example 7, but differs as follows.
The high frequency conditions were a compression speed of 27 seconds/cycle and a compression ratio of 30%.

(Example 9) Manufacturing of fixed-length compacted plate This is basically the same as Example 7, but differs as follows.
The high frequency conditions were a compression speed of 30 seconds/cycle and a compression ratio of 28%.

(Example 10) Manufacturing of fixed-length compacted plate This is basically the same as Example 7, but differs as follows.
In the cooling step, some of the compacted wood boards are placed in a -130°C environment using liquid nitrogen freezing technology to cool to room temperature for 15 minutes, and then vertical joining is performed. Typically, some of the compacted wood boards are cooled to room temperature using liquid nitrogen freezing technology and then removed from the liquid nitrogen freezer box. In other embodiments, "room temperature" refers to the temperature before vertical joining. For pipeline operations, the compacted wood boards are cooled to a temperature of 3-5°C in a -130°C environment, and then sent out through the pipeline to enter the vertical joining equipment.

(Example 11) Manufacturing of fixed-length compacted plate This is basically the same as Example 10, but differs as follows.
In the cooling treatment step, some compacted wood boards are placed in a −140° C. environment using liquid nitrogen freezing technology to cool down to room temperature for 12 minutes, and then longitudinal bonding is carried out.

(Example 12) Manufacturing of fixed-length compacted plate This is basically the same as Example 10, but differs as follows.
In the cooling treatment step, some compacted wood boards are cooled to room temperature in a -150°C environment for 9 minutes using liquid nitrogen freezing technology, and then joined in the longitudinal direction.

(Comparative Example 1) Production of a fixed-length compacted plate This is basically the same as Example 1, except that the water layer deposition step is omitted.

(Comparative Example 2) Manufacturing of fixed-length compacted plate This is basically the same as Example 1, except that the water layer deposition step is omitted and the first preheating step is changed to preheating using a high-frequency hot press.

(Comparative Example 3) Manufacturing of fixed-length compacted plate This is basically the same as Example 1, but differs as follows.
In the first preheating step, the temperature of the infrared irradiation space is 160° C. to obtain several preheated cork strips.
In the water layer application step, the water layer is applied once in total using one water layer coater equipped with the set of coating rollers.

(Comparative Example 4) Manufacturing of fixed-length compacted plate This is basically the same as Example 4, but differs as follows.
In the step of forming a vertical joining contact surface,
In S1, the joint end surface of the compacted wooden board is processed and formed into a flat surface.
In the step of forming a lateral joining interface,
In S1, the joint end surfaces of the compacted wooden boards are processed and shaped into an inclined plane.

(Comparative Example 5) Manufacturing of fixed-length compacted plate This is basically the same as Example 4, but differs as follows.
In the step of forming a vertical joining contact surface,
In S1, the joint end surface of the compacted wooden board is processed and formed into an inclined plane,
In the step of forming a lateral joining interface,
In S1, the joining end surfaces of the compacted wooden boards are processed and formed into sawtooth surfaces.

(Comparative Example 6) Production of fixed-length compacted plate This is basically the same as Example 4, but differs as follows.
In the step of forming a vertical joining contact surface,
In S2, the weight ratio of PVB resin to PVB resin particles is 14:1;
In the step of forming a lateral joining interface,
In S1, the joint end surfaces of the compacted wooden boards are processed and shaped into an inclined plane.

(Comparative Example 7) Production of fixed-length compacted plate This is basically the same as Example 7, with the following differences.
The high frequency condition is a compression speed of 40 seconds/cycle.

(Comparative Example 8) Production of fixed-length compacted plate This is basically the same as Example 7, with the following differences.
The high frequency condition is a compression speed of 10 seconds/cycle.

(Comparative Example 9) Production of fixed-length compacted plate This is basically the same as Example 7, with the following differences.
The high frequency condition is a compression ratio of 20%.

The following tests will be conducted with reference to the following examples and comparative examples.

(Test Example 1) Measurement of Hairline A 3 mm thick surface layer (the surface layer exposed to infrared radiation) of a wooden board was cut with a saw along the thickness direction to remove it, exposing the inner layer, and the density and moisture content were measured. Subsequently, a total of six test pieces were cut out: four at the four corners and two at the center.

The dimensions of the test material are length 150±1 mm and width 50±0.5 mm.

The test method involves inspecting the hairline on the surface of the test material with normal vision (or corrected to normal vision) and a 6x magnifying glass at an illumination intensity of 800lx to 1000lx.

Regarding hairline grades, Grade 5 means there are no hairlines, Grade 4 means there are hairlines only with a 6x magnifying glass, and Grade 3 means the hairlines are visible to the naked eye. The hairline score for one piece of wood is the arithmetic average of the hairline grades for all test materials, approximated to an integer, and the results are shown in Table 1.

(Table 1) Hairline grade measurement results

As can be seen from the test results, Examples 1-3 had significantly fewer hairlines than Comparative Examples 1-3. Water-layer-attached cork strips generate hot steam during high-frequency hot pressing, which can further alter the wood's properties. A comparison of Examples 1-3 with Comparative Example 2 shows that combining infrared preheating with high-frequency hot pressing of water-layer-attached cork strips produces essentially the same hairline grade as high-frequency preheating and hardening, but the former is more suitable for pipelines and less expensive, and is superior to the latter, which completes preheating using a high-frequency hot press. A comparison of Examples 1-3 with Comparative Examples 1 and 3 shows that infrared preheating or improper water layer attachment causes hairlines to form in the 2-4 mm depth of the surface layer of the poplar compacted board exposed to infrared radiation. As evidenced by Test Example 1, the methods of Examples 1-3 essentially solve this problem.

(Test Example 2) Bending Strength and Bending Modulus Test The bending strength was determined in accordance with GB/T 1936.1-2009 "Test Method for Bending Strength of Wood," and the bending modulus was determined in accordance with GB/T 1936.2-2009 "Method for Measuring Bending Modulus of Wood." The test results are shown in Tables 2 and 3.

(Table 2) Bending strength test results

(Table 3) Flexural modulus test results

As can be seen from the test results, Examples 1 to 6 have superior bending strength and bending modulus compared to Comparative Examples 4 to 6. The bending strength and bending modulus performance of Examples 4 to 6 are even better. Thus, the triple compression method is more advantageous. A comparison of Examples 4 to 6 with Comparative Example 4 shows that in the step of forming the vertical bonding contact surface, the bonding end surfaces of the compacted wood boards are processed into a sawtooth surface, increasing the amount of resin carried and significantly improving the bending strength and bending modulus performance. A comparison of Examples 4 to 6 with Comparative Example 5 shows that in the step of forming the horizontal bonding contact surface, the bonding end surfaces of the compacted wood boards are processed into a sawtooth surface, but this does not significantly improve the bending strength and bending modulus performance. A comparison of Examples 4 to 6 with Comparative Example 6 shows that in the step of forming the vertical bonding contact surface, the weight ratio of PVB resin to PVB resin particles significantly affects the improvement of bending strength and bending modulus performance.

(Test Example 3) Screw gripping force test The method for detecting screw gripping force is GB/T 17657-2013 "Test methods for physicochemical performance of artificial boards and decoratively finished artificial boards," and the test results are shown in Table 4.

(Table 4) Screw gripping force test results

As can be seen from the test results, the screw grip strength of Examples 4-9 is superior to that of medium-density board, fine wood board, and general particle board. The screw grip strength of Examples 7-9 is similar to that of textured board that can be finished. The screw grip strength of Examples 4-9 on the board edges is essentially the same, but the screw grip strength of Examples 7-9 at the board joints is superior to that of Examples 4-6. A comparison of Examples 4-6 and 7-9 shows that there is no significant difference in compression speed and compression ratio.

(Test Example 4) Measurement of formaldehyde content The criteria for formaldehyde (mg/L) are GB 18584-2001 "Limited amounts of harmful substances in wooden furniture as interior construction materials", and the test results are shown in Table 5.

(Table 5) Formaldehyde test results

The test results showed that Examples 1, 4, 7, and 10 all met the formaldehyde guidelines set out in GB 18584-2001, "Limits on Harmful Substances in Wooden Furniture Interior Construction Materials."

(Test Example 5) Measurement of accelerated aging performance 1. After the test material was cycled six times by hot water immersion - spray evaporation - freezing - drying - spray evaporation - drying, the screw gripping force and water absorption thickness expansion rate of the test material were measured.

2. The equipment used is a steam accelerated aging test box for artificial boards, which meets the equipment requirements for "Measurement of Accelerated Aging Performance" in GB/T 17657-2013, "Test Methods for the Physical and Chemical Performance of Artificial Boards and Decoratively Finished Artificial Boards."

3. Dimensions of the test material The dimensions of the static bending strength test material are (length 450±1 mm, width 50±1 mm, thickness 20±1 mm),
The dimensions of the screw gripping force test material are (length 75±1 mm, width 50±1 mm, thickness 20±1 mm),
The dimensions of the water absorption thickness swelling test material are (length 50±1 mm, width 50±1 mm).

4. Balancing of test material The test material is placed in an environment of 20±2°C and a relative humidity of 65±5% until it reaches the specified mass (weigh it twice every 24 hours, and if the difference in mass between the two weighings is less than 1% of the mass of the consolidated material, the mass is considered to be the specified mass).

5. Test Method In the accelerated aging cycle, the test material is subjected to six cycle tests. Each cycle includes the following steps:
a) The test material is immersed in warm water at (49±2)°C for 1 hour.
b) The test material is sprayed and evaporated in steam at (93±3)°C for 3 hours.
c) The test material is frozen in a freezer at (-12±3)°C for 20 hours.
d) The test material is dried in a ventilation drying box at (99±2)°C for 3 hours.
e) The test material is sprayed and evaporated in steam at (93±3)°C for 3 hours.
f) The test material is dried in a ventilation drying box at (99±2)°C for 18 hours.

After all six cyclic accelerated aging tests were completed, the test materials were placed under conditions of (20±2)°C and relative humidity of (65±5)% for at least 48 hours, followed by performance testing. The test results are shown in Table 6.

Table 6: Accelerated aging performance measurements

As can be seen from the test results, after accelerated aging, the screw grip strength of Examples 4, 7, and 10 all decreased, but was still superior to or comparable to that of medium-density board, fine wood board, and general particle board. Examples 7 and 10 had lower water absorption thickness expansion rates than Example 4, thereby demonstrating the triple compression technology's structural anti-rebound performance. Example 10 had the lowest water absorption thickness expansion rate, indicating that quenching anti-rebound and structural anti-rebound performance can work synergistically.

Although the present invention has been described in detail above through the general description, specific embodiments and tests, it is obvious to those skilled in the art that some modifications or improvements can be made based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are included in the scope of the claims for protection of the present invention.

Claims (8)

a first preheating step of irradiating several cork slabs with a moisture content of 10% to 20% with infrared light to raise the average temperature to 80 to 90°C to obtain several preheated cork slabs, the cork slabs being poplar slabs;
a water layer deposition step of depositing a water layer on the surface of the preheated cork slab irradiated with infrared light to obtain several water layer-deposited cork slabs;
a high-frequency hot pressing step in which the water-layer-attached cork boards are subjected to a heat compression treatment and hardening treatment under high-frequency conditions to obtain several compacted wood boards;
A cooling treatment step of cooling some of the densified wood boards to an average wood temperature of 70 to 90 ° C or room temperature, and the room temperature is 3 to 5 ° C.
a longitudinal joining step of joining longitudinally adjacent cooled compacted wood board strips to obtain several longitudinally joined compacted wood boards;
a horizontal joining step of joining adjacent longitudinally joined compacted wood boards in the width direction to obtain several horizontally joined compacted wood boards;
A sizing step of cutting the several transversely joined compacted wood boards into several standard-sized compacted boards.
A process for producing compacted plates to length based on high frequency. The water layer-attached cork strip is subjected to a second preheating step and then to the high-frequency hot pressing step, during which:
2. The process according to claim 1, wherein in the second preheating step, some of the water-layer-attached cork strips are irradiated with infrared light to maintain an average temperature of 80-90°C. The manufacturing process described in claim 2, characterized in that in the first preheating step and/or the second preheating step, infrared irradiation is performed in an infrared irradiation space, and the temperature of the infrared irradiation space is 130 to 150°C. The manufacturing process described in claim 3, characterized in that, in the water layer application step, water is applied or sprayed onto the surface of the preheated cork strip one to four times. In the high-frequency hot pressing step, two to four water-layer-attached cork boards are stacked together, and then immediately subjected to a heat compression and hardening treatment under high-frequency conditions to obtain several laminated compacted wood boards;
In the longitudinal joining step, adjacent laminated compacted wood board strips are joined in the longitudinal direction to obtain several longitudinally joined compacted wood boards;
5. The manufacturing process of claim 4. In the vertical joining step, the vertical joining contact surfaces of the longitudinally adjacent compacted wood boards of each vertically joined compacted wood board are curved or inclined surfaces, and the inclined surfaces include inclined planes or inclined curved surfaces;
In the lateral joining step, the lateral joining contact surfaces of adjacent densified wood boards in the width direction of each lateral joined densified wood board are flat or inclined, and the inclined surfaces include inclined flat surfaces or inclined curved surfaces;
6. The manufacturing process of claim 5. 7. The manufacturing process of claim 6, wherein adjacent vertical bonding contact surfaces or adjacent horizontal bonding contact surfaces are connected by a resin layer, and the resin layer includes one or more of a PVA resin layer, a PVB resin layer, and a PVC resin layer . The steps of forming the resin layer are as follows.
In S1, the joint end surface of the compacted wood board is processed into a curved surface or an inclined surface, and the inclined surface includes an inclined plane or an inclined curved surface;
In S2, the resin is hot-melted to produce a hot-melt resin, and the hot-melt resin is applied to the joining end surface of the compacted wooden board;
The manufacturing process according to claim 7, wherein in S3, a first biasing force is applied to press the joining end surfaces of adjacent compacted wooden boards.