JPH0416041B2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention applies adhesive to the surface of a veneer veneer and laminates it into multiple plies parallel to the fiber direction or partially perpendicular to the fiber direction. Veneer laminated materials are produced by heating and pressurizing continuous intermediate products that are conveyed intermittently or continuously, commonly known as LVL (laminated veneer lumber) or LVB (laminated veneer board). The present invention relates to improvements in the heat-pressing method for laminated veneer materials.

(b) Prior art The heat-pressing method of this type of laminated veneer material according to the prior art includes, for example, Patent No. 982535 (Japanese Patent Publication No. 14641/1983).
As disclosed in continuous manufacturing equipment for laminated veneer materials, etc., "continuous heating plates equipped with heating sources such as steam, electric heat, or high-frequency power are placed vertically facing each other with a steel belt conveyor in between, and By activating a number of hydraulic cylinders attached to the movable platen of the heating platen while the steel belt conveyor is at rest, the surface of the intermediate product, that is, the veneer veneer, carried on the steel belt conveyor is A veneer lamination process in which a continuous intermediate product is coated with adhesive and laminated into multiple plies parallel to the fiber direction or partially perpendicular to the fiber direction, and then heated and pressed while being conveyed intermittently or continuously. A method for heat pressing materials was developed.

(C) Problems to be Solved by the Invention The conventional heat pressing method for laminated veneer materials as described above involves applying adhesive to the surface of the veneer veneer immediately before the hot pressing operation, and applying a multi-layer adhesive to the surface of the veneer veneer. The first step was to create a laminate of intermediate products organized into plies, and insert this directly between the upper and lower heating plates to start heat pressure. Active heating is limited to only the surface layer of the intermediate product, and the entire intermediate layer is not sufficiently heated until after repeated intermittent or continuous conveyance operations for a while, so there is no adhesive residue during the conveyance process. It is easy to cause plates to shift due to hardening, resulting in tunnels and overlaps at joints.Also, even if high-frequency power is used as a heating source, it is difficult to actively heat only the intermediate layer of the intermediate product at the initial stage. The surface layer is an electrode,
Since the whole body cannot be sufficiently heated until after the intermittent or continuous conveying operation has been repeated for a while due to the cooling effect of a pressure plate, etc., the adhesive is There were problems such as plate slippage due to uncured material, and tunnels and overlaps were likely to occur at joints. Furthermore, by superimposing the above heating source using steam, electric heat, etc. and the heating source using high frequency power on the same heating plate, it is possible to heat the surface layer and intermediate layer of the heated press. Attempts have been made to equalize the time difference as much as possible to eliminate the occurrence of tunnels and overlaps at the joints due to sheet displacement due to uncured adhesive during the conveyance process. This type of heating source superimposition method on the same heating plate requires the use of a relatively long heating plate that uses steam, electric heat, etc. as the heating source as it is as an electrode for applying high-frequency power. At the application electrode, standing waves are superimposed on the applied high-frequency power, causing significant heating spots, and in order to reduce these developments as much as possible, countermeasures such as installing the heating plate and high-frequency oscillator in multiple stages are being taken. However, such countermeasures not only result in the creation of several isolated areas that are not heated and pressurized during the heat-pressing process, intermittent heat curing of the adhesive is inhibited, and the adhesive strength becomes unstable. This is intended to eliminate the drawbacks of this type of conventional technology, which had a series of functional, structural, and economical obstacles such as requiring a large installation space and increasing equipment costs.

(d) Means for solving the problem The present invention aims to eliminate the drawbacks of the above-mentioned prior art.
A heating plate that is heated by high-frequency power and a heating plate that is heated by steam, electric heat, etc. are placed separately in the front and back, and the former heating plate performs a temporary adhesion operation that heats and presses localized areas of the intermediate product in a horizontal striped pattern. In addition, the latter heating plate is configured to function effectively in the stepwise thermal curing of adhesive applied to the surface of a veneer veneer by applying a main adhesion operation that uniformly heats and presses the entire surface of the plate. That is, the present invention has the following features: (a) A continuous intermediate product is temporarily stuck together by heat-pressing its local area in a horizontal striped pattern using a lattice-shaped high-frequency electrode disposed perpendicular to the conveying direction, and (b) ) The continuous intermediate product temporarily glued to the horizontal striped pattern is then inserted between continuous hot discs heated by steam, electric heat, etc., and the entire surface is uniformly hot-pressed to make it permanently glued. This is a hot pressing method for laminated veneer material consisting of the following.

(E) Effect The operation of partially heating and pressurizing the intermediate product of the present invention in a vertical striped pattern to make it temporarily stick together, and the operation of uniformly heating and pressing the entire surface to make it permanently stick, are illustrated in FIG. This process is carried out sequentially during the conveyance process of a long intermediate product 1 during the heat-pressing process, and a thermosetting adhesive is applied to both sides or one side of the surface of each individual veneer veneer 2 using a spreader, flow coater, etc. The continuous intermediate product 1, which is coated and laminated into multiple plies parallel to the fiber direction or partially perpendicular to the fiber direction using various construction devices, is intermittently or continuously longitudinally coated by a conveyor, presser, etc. The material is conveyed in the direction and reaches the temporary adhesion process. The structure of the continuous intermediate product 1 that has undergone the temporary adhesion process is usually such that the joint parts 3 of the individual veneer veneers 2 are overlapped in a scarf joint style by cutting the edges into symmetrical slopes. or the cut edges are butted together in a butt joint style, or they are piled up and overlapped in an overlap joint style, and at least the joint part 3 is Since the veneer veneer 2 is not integrally bonded with hot melt resin, etc., the veneer veneer 2 may be damaged due to vibration during transportation, expansion of the material due to absorption of moisture, volatile matter, etc. of the adhesive applied to the board surface, etc. As long as the adhesive applied to the board surface is not cured, the board is likely to shift even between some layers. Therefore, in order to eliminate the occurrence of tunnels and overlaps at the joint portion 3 caused by this type of sheet displacement, the present invention uses a grid-like high-frequency electrode and In the temporary adhesion zone A formed by the pressure mechanism, the local area is heated to about 80 to 100℃ in a horizontal striped pattern for several tens of seconds, for example, a width of 50℃.
A temporary adhesion operation is performed in which a large number of board attachment points 4 are heated for 20 to 70 seconds to form a temporary adhesion state in a horizontal striped pattern with a pitch of about 150 mm.

Next, in the present invention, the intermediate product 1, which has been plated in a horizontal striped pattern by the preliminary adhesion operation, is conveyed intermittently or continuously by a conveyor, pusher, etc., and inserted into the next stage of the main adhesion process. . The intermediate product 1, which is inserted into the main adhesion process and temporarily attached in a horizontal striped pattern, is heated by a continuous heat source equipped with a heating source such as steam or electric heat and a pressurizing mechanism so as to uniformly cover the entire surface from the top and bottom. In the main adhesion section B, which is made up of a board, the entire surface is heated uniformly at about 100 to 110°C for several minutes to remove the total amount of the thermosetting adhesive applied to the board surface of the veneer veneer 2. The main adhesion operation, in which the materials are completely heat-cured in this section, is carried out in stages following the preliminary adhesion operation in the previous stage.

(f) Example The example shown in FIG. 1 shows the configuration of incidental devices such as a heating plate and a pressurizing mechanism disposed in the preliminary adhesion process and the main adhesion process of the present invention. The continuous intermediate product 1, which has been laminated into multiple plies in the adhesive application process and the assembly process in the previous stage, is conveyed intermittently or continuously by a steel belt conveyor 5, etc., and is first temporarily coated. It arrives in the high frequency tack press 6 of the sticking process. The high-frequency tuck press 6 is pressurized with an average clamping force of about 6 to 8 kg/cm ² by a movable platen 8 equipped with a hydraulic cylinder 7 and a fixed platen 9 facing the movable platen 8, and is attached to the movable platen 8. A high-frequency power of about 2 to 3 KW per electrode is applied to several tens of grid-shaped high-frequency electrodes 11 buried in the insulator 10 from a high-frequency oscillator 12.
It is configured to apply heat for a second to approximately 80 to 100°C in a horizontal striped pattern to cause temporary adhesion between local layers. The lattice-shaped high frequency electrode 11 is configured to be able to heat and press, for example, between the layers of the intermediate product 1 in a horizontal striped pattern with a width of 50 mm and a pitch of 150 mm for about 20 to 70 seconds. In order to prevent cooling of the lower layer of the intermediate product 1 including the steel belt conveyor 5 as much as possible, a heat-retaining heat plate 13 using steam, electric heat, or the like as a heating source is usually attached.

Next, the continuous intermediate product 1 is connected to the high frequency tack press 6, and the continuous intermediate product 1, which has been locally heated and pressed into a horizontal striped pattern by the high frequency tack press 6, is then conveyed into the hot press 14 by the steel belt conveyor 5, etc. Here, the continuous movable platen 16 and fixed platen 17 equipped with the hydraulic cylinder 15 apply an average clamping force of 6 to 8 kg/cm ^{2 .}
The whole surface is uniformly heated at about 100 to 110°C for several minutes by supplying a heating source such as steam or electric heat to the heating plates 18 and 19 attached to the movable platen 16 and fixed platen 17. In this way, all of the thermosetting adhesive applied to the surface of the veneer veneer is completely thermally cured, and a stepwise adhesive thermosetting method is taken to form a continuous veneer. The laminated material product 20 is produced intermittently and is delivered to a subsequent finishing process including a cross cut saw and the like.

(G) Effects of the Invention As described above, the present invention has a heating plate heated by high-frequency power and a heating plate heated by steam, electric heat, etc., arranged separately in the front and back, and the former heating plate is placed in the middle. The adhesive applied to the surface of the plywood veneer is gradually applied to the surface of the plywood veneer by a preliminary adhesion operation in which local areas of the product are heated and pressed in a horizontal striped pattern, and by a main adhesion operation in which the latter heating plate is uniformly heated and pressed over the entire surface. The present invention is designed to function effectively for thermosetting, and the present invention eliminates the phenomenon in which plates shift due to uncured adhesive during transportation, resulting in tunnels and overlaps at joints. It can be completely eliminated, and the amount of heating heat from high-frequency power during temporary adhesion is added to the amount of heating heat from steam, electric heat, etc. during the next main adhesion, and at least the initially horizontal striped temporary adhesion area quickly reaches the desired adhesive strength. This method is similar to the hot stacking method, which shortens the overall heat pressure time and accelerates the heat curing of the adhesive by depositing it at a high temperature after pressure is removed, resulting in high quality. Not only has it been possible to produce laminated veneer products with high efficiency, but the present invention also enables the application of high-frequency power in a horizontal striped pattern to the intermediate product using high-frequency electrodes installed perpendicular to the conveying direction. This type of intermediate product, in which the fiber direction of most of the veneer veneers is parallel to the direction in which the horizontal stripes are arranged, has a stiffness in the fiber direction that increases the ratio of the non-heated part to the heated part by several times. It was possible to maintain a state of temporary adhesion to the extent that it did not cause sheet slippage, even if the degree was wide. This invention means that the temporary adhesion operation of products can be completed safely, and it also contributes to the reduction of equipment costs and electricity costs in the temporary adhesion process, and is an extremely effective invention.

[Brief explanation of drawings]

The figure shows an example of implementation of the present invention,
FIG. 1 is a side view of the apparatus, and FIG. 2 is a plan view of the intermediate product in a hot and pressurized state. 1... Intermediate product, 2... Veneer veneer, 11...
High frequency electrode, 18, 19...heat plate.

Claims (1)

[Claims] 1 A continuous intermediate product made by applying adhesive to the surface of a veneer veneer and laminating it into multiple plies parallel to the fiber direction or partially perpendicular to the fiber direction is conveyed intermittently or continuously. In the heat-pressing process of the veneer laminated material, in which the continuous intermediate product is heated and pressurized, the continuous intermediate product is locally hot-pressed into a horizontal striped pattern using a grid-like high-frequency electrode provided perpendicular to the conveying direction, so that it temporarily sticks together. In addition, the continuous intermediate product temporarily glued to the horizontal striped pattern is then inserted between continuous hot discs heated by steam, electric heat, etc., and the entire surface is uniformly hot-pressed to make it permanently glued. A method of hot pressing for laminated veneer material, which is characterized by: