JPS5910908B2 - Manufacturing method of backing veneer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 35 The present invention relates to a method for producing a backing veneer by bonding a porous backing sheet such as paper or cloth to a veneer, and which does not cause waving or wrinkles in the product.

The conventional manufacturing method for backing veneer is to apply an adhesive to the backing sheet base material, place the veneers on top of it, and then heat-press the adhesive. However, the backing veneer manufactured by this method has a lot of waving and wrinkles, and it is difficult to obtain processing precision when using this product, so the commercial value is very low. There were flaws.

Considering the causes of the above drawbacks: (1) Because the backing base material is thin and has great flexibility, it is impossible to suppress dimensional changes caused by shrinkage of the veneer, so waving and wrinkles are likely to occur. (2) During heat-pressure bonding, the voids in the base material disappear, making it difficult for water vapor generated from the veneer and adhesive to be discharged, causing the adhesive to completely harden and dissolve. This is thought to be due to the fact that the moisture content of the veneer remains high even immediately after pressing, and the veneer then shrinks due to residual heat and natural drying, causing waving and wrinkles.

Therefore, with conventional methods, it was impossible to finish a veneer with a high moisture content into a beautiful backing veneer without causing waves or wrinkles. Attempts have been made to reduce the ratio to 20% or less and to use water-insoluble adhesives.

However, the waving caused by shrinkage spots that occur in the veneer during drying cannot be improved even after heat pressing because the backing sheet is flexible. The only thing that could be done was to prevent ripples. However, even in this case, water-insoluble adhesives are expensive and have poor workability, so they have only been used for very specific applications. The present invention was completed as a result of various studies in view of the above facts, and uses a mesh sheet during heat pressing to drain water generated from high moisture content plates and adhesives to the outside of the press machine. To easily obtain a backing veneer with good dimensional stability without waviness even when high moisture content veneer or water-soluble adhesive is used by completing drying and eliminating drying shrinkage of the veneer after depressurization. This made it possible.

Next, a more detailed explanation will be given using figures.

Figure 1 is a cross-sectional view illustrating the movement of water vapor during compression when a veneer is attached to a plywood base material, and Figure 2 is a cross-sectional view illustrating the movement of water vapor during compression when a backing sheet is attached to a veneer. This is a sectional view explaining the situation, and in the figure, 1 is a hot plate of a press, 2 is a mirror plate, 3 is a veneer, 4 is an adhesive, 5 is a plywood base material, 6 is a movement path of generated water vapor, 7 shows the backing sheet, and as can be seen from the figure, the movement path of water vapor generated from the veneer and adhesive is compressed during the heat-pressing operation, making it extremely difficult for the water vapor to escape.

Therefore, in the present invention, as shown in FIG. 3, an adhesive 4 is applied onto a flexible and porous backing sheet 7 such as paper or cloth, and a veneer 3 is juxtaposed thereon. Furthermore, by overlapping mesh sheets 8 made of metal or hard plastic on the non-veneer side in order to provide a gap through which the outside of the press machine passes, high-temperature water vapor generated from the veneer and adhesive during hot pressing can be prevented. It penetrates the backing sheet and can be easily discharged out of the press machine.

It is a necessary condition for the veneer used in the present invention to be free of waving, but in the case of dry veneers that already have waving, the waving will disappear after the veneer is returned to a wet state above the fiber saturation point, so it is not necessary to This means that even veneers with high moisture content can be used.

The backing sheet must be porous to allow water vapor to pass through, but the adhesive may ooze out as water vapor penetrates the backing sheet, so appropriate ventilation is required in relation to the amount of adhesive applied. It is necessary to choose one that has gender. As for the material, porous materials such as kraft paper, synthetic fiber paper, Japanese paper, nonwoven fabric, and asbestos paper are suitable. Water-soluble adhesives such as urea-based, vinyl acetate-based, and α-olefin-based adhesives can be used, but other solvent-based adhesives,
It is also possible to have a backing sheet impregnated with a small amount of adhesive.

The mesh sheet must be able to maintain the air gap outward from the press machine even when it is heated and pressed, and its material must be a wire material that does not undergo significant plastic deformation at a temperature of 150°C and an air pressure of 1kg/C77f. Must be woven;
Specifically, iron, stainless steel, brass, other metals, and hard plastics such as fluorine-based and polyester-based are used.

Next, regarding the method of weaving the net-like sheet, a simple plain weave can sufficiently achieve the purpose, but any weave that creates voids in the thickness direction, such as twill weave, plain tatami weave, twill tatami weave, and basket weave, can be used. The other one can also be used. The gaps in the mesh are a factor in pressure unevenness, clogging, and durability, and are related to each other, but in this case, the presence of the backing sheet is advantageous in terms of pressure unevenness and clogging. However, in the case of plain weave, 5 meshes or more is desirable from the viewpoint of pressure spots, and 20 meshes or more from the viewpoint of clogging and durability.
A value of 0 mesh or less is appropriate. 4 and 5 show an enlarged perspective view and an enlarged sectional view of the reticulated sheet, and 9 in the figure shows the wire material constituting the reticulated sheet, 1
0 indicates a gap to the outside of the press created by the mesh sheet. Since the mesh sheet can be separated from the backing veneer and reused after finishing the processing operation, the cost for using the mesh sheet is extremely low.

As mentioned above, the backing veneer obtained by the manufacturing method according to the present invention is different from the backing veneer obtained by the conventional method by drying the veneer to a moisture content of about 5 to 18% during heat pressing, which is called 11 drying. The backing veneer is in a set state and is fixed to the dimensions of the veneer before pressing, and does not shrink even after the pressure is released, resulting in a finished backing veneer with excellent dimensional stability and no waving.

This is particularly effective in the case of laminated complex patterned veneers with patterns that are perpendicular to the fiber direction, or veneers with a butt end surface. However, by implementing the method of the present invention, the moisture content is higher than the saturation point of the fiber, which means that it is in a wet state, that is, the swollen size. Since the backing veneer is fixed at the side of the veneer, it is possible to produce a beautiful backing veneer with good dimensional stability and no waving or wrinkles caused by drying shrinkage of the veneer. In addition, since water vapor is easily discharged during work, the temperature rises quickly and compaction time is short, making it suitable for mass production.Furthermore, in the case of wet veneers, the veneer can be fixed in a fully stretched state. Because of this, it is possible to eliminate the 5 to 10% area loss due to drying shrinkage, which helps to save valuable wood resources, and the economic effect is enormous, making it an extremely useful manufacturing method.

Next, further explanation will be given with reference to examples. Example An adhesive made of a blend of vinyl acetate and urea resins was applied to a nonwoven fabric having a unit weight of 1007/M2 at a ratio of 807/M2.

Next is 0.3mW! Moisture content sliced to a thickness of 50-7
A 0% laminated complex patterned veneer was placed on the surface coated with the adhesive, and on the other hand, a 100 mesh stainless steel wire mesh was placed on the back of the non-woven fabric and heated at a temperature of 120°C and a pressure of 51°C using a conventional method.
<9/C77L was heated and pressed for 1 minute to obtain a beautiful backing veneer with no undulations and stable dimensions.

[Brief explanation of drawings]

Figure 1 is a diagram showing the movement of water vapor during compression when a veneer is attached to a plywood base material, Figure 2 is a diagram when a backing sheet base material is used instead of the plywood base material, and Figure 3 4 is a perspective view of the mesh sheet, and FIG. 5 is an enlarged cross-sectional view of the mesh sheet, showing the voids for water vapor movement that occur during compaction. shows. In the figure, 1...Brace heating plate, 2...Mirror plate, 3...Single plate, 4...Adhesive, 5...
... Plywood base material, 6 ... Water vapor movement path, 7 ... Backing sheet, 8 ... Reticular sheet, 9 ... Reticular sheet Wire material constituting 1
0... Indicates the gap of the mesh sheet to the outside of the press machine.

Claims (1)

[Claims] 1. A method for manufacturing a backing veneer by laminating a porous backing sheet via an adhesive on a high moisture content veneer whose water content is equal to or higher than the fiber saturation point. A method for manufacturing a backing veneer, characterized by heat-pressing the veneer side with a mesh sheet made of a non-hygroscopic material. 2. The method for producing a backing veneer according to claim 1, wherein the backing sheet is paper. 3. The method for manufacturing a backing veneer according to claim 1, wherein the backing sheet is cloth. 4. The method for manufacturing a backing veneer according to claim 1, wherein the backing sheet is a nonwoven fabric. 5. The method for manufacturing a backing veneer according to claim 1, wherein the backing sheet is asbestos paper. 6. The method for producing a backing veneer according to any one of claims 1 to 5, wherein the adhesive is a urea-based water-soluble adhesive. 7. The method for producing a backing veneer according to any one of claims 1 to 5, wherein the adhesive is a vinyl acetate water-soluble adhesive. 8. The method for producing a backing veneer according to any one of claims 1 to 5, wherein the adhesive is an α-olefin water-soluble adhesive. 9. The method for manufacturing a backing veneer according to any one of claims 1 to 8, wherein the reticulated sheet is made of iron. 10. The method for producing a backing veneer according to any one of claims 1 to 8, wherein the reticulated sheet is made of stainless steel. 11. The method for producing a backing veneer according to any one of claims 1 to 8, wherein the mesh sheet is made of brass. 12. The method for producing a backing veneer according to any one of claims 1 to 11, wherein the reticulated sheet is a twill weave. 13. The method for producing a backing veneer according to any one of claims 1 to 11, wherein the reticulated sheet is made of tatami weave. 14. The method for producing a backing veneer according to any one of claims 1 to 11, wherein the reticulated sheet is made of bamboo weave. 15. The method for producing a backing veneer according to any one of claims 1 to 11, wherein the reticulated sheet is a plain weave and has a mesh size of 5 mesh or more and 200 mesh or less.