JPS6140102A - Manufacture of flitch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing plywood for construction, construction, or furniture.

[Conventional technology]

When manufacturing plywood, knotted veneers (especially softwood veneers have many knots) will shed knots during drying, and when the knots reach the end of the plywood cut to a certain size, the knots will be removed. This would cause dents in the plywood, reducing the plywood's strength and making it look bad, so paper tape was pasted to the knots in advance to fix the knots.

[Problem that the invention seeks to solve]

When paper tape is pasted to the knots of veneer, there is a drawback that the adhesive strength of the plywood decreases due to the separation of the paper tape.

This invention aims to prevent knots from falling out of veneers and also to prevent a decrease in adhesive strength of plywood.

[Means for solving problems]

When manufacturing plywood by laminating wood veneers, this invention
The present invention relates to a method for manufacturing plywood, which is characterized by pasting a water-soluble polymer film on the knots of a veneer.

This invention will be explained in detail below.

A water-soluble polymer film such as polyvinyl alcohol or vinylon is pasted using a Teflon roll or the like on the knots of a South Sea wood veneer such as lauan veneer or softwood veneer obtained by cutting with a rotary lace or slicer. . Here, the knot part of the veneer includes the knot and the part of the veneer adjacent to the outer periphery of the knot, and plywood is a plywood or fiberboard made of veneer arranged perpendicularly to each other from the direction of the fibers. When applying a water-soluble polymer film, including laminated veneers made in the same direction, a small amount of moisture is required, so apply a small amount of water to the surface of veneers with a low moisture content. There are two ways to attach a water-soluble polymer film: ■ Simply attach it to the veneer and let it dry, and ■ Gently attach it after placing it on the veneer. There are two types: those that require heat and pressure. The properties of the water-soluble polymer films of ■ and ■ differ depending on their degree of saponification.

If the degree of saponification is 88 mol% or less, it is very soluble in water and has the property of sticking as long as there is water;
If it exceeds 8 mol%, it is water soluble but difficult to dissolve in water at room temperature and requires heating. For example, the degree of saponification is 88 to 97.
If it is mol%, the temperature of the water to be dissolved needs to be 40 to 60°C, and if it is close to 100 mol%, a temperature of 100°C or higher is required. Note that, as a matter of course, the heating temperature must be lower than the melting temperature of polyvinyl alcohol.

The veneer to which water-soluble polymer film is attached is made into plywood after the adhesive is applied to the adhesive-coated surface using a spreader and then assembled in the assembly process, followed by a cold-pressing process and a hot-pressing process. Since the adhesive used in plywood production is water-soluble (including emulsion), the adhesive and water-soluble polymer film are compatible, and there is almost no negative effect on the adhesive strength of the plywood.

[Example 1] Diameter of 3mm thick veneer cut with rotary lace 20mm
A water-soluble polyvinyl alcohol film having a saponification degree of 84 mol% and having a size of 4 cm x 4 cm and a thickness of 0.07 cm was adhered to the intestinal segment by pressing with a Teflon roll, and then dried with a roll dryer.

A water-soluble urea resin adhesive was applied to both sides of this veneer using a spreader, and a front plate and a back plate with a thickness of 1*ie were used in a sandwich-like manner.
The desired plywood was obtained by hot pressing at a pressure of 8 kg/am'' for 2 minutes. When the knots of the plywood were cut, there were no loose knots, and no decrease in adhesive strength was observed.

[Example 2] A node of diameter 50 intestines of a 3-inch, 9-thickness veneer cut with a rotary lace was cut with a size of 7 cs x 7 c (1, (17
A water-soluble polyvinyl alcohol film with a saponification degree of 98 mol% and having a thickness of 1 layer was pressed with a Teflon roller and placed in a state where it was tightly adhered by moisture, then it was lightly pressed at 120°C to adhere it, and it was dried with a roll dryer. Dry. 0. A desired plywood was obtained in the same process as in Example 1.

I tried cutting the knots of this plywood, but no knots came out.

Further, no decrease in adhesive strength was observed.

[Effects of the Invention] Since the present invention is configured as described above, it has the advantage of being able to prevent the veneer from becoming loose and also prevent the adhesive strength of the plywood from decreasing.

Claims (1)

[Claims] A method for manufacturing plywood, which is characterized in that when manufacturing plywood by laminating wood veneers, a water-soluble polymer film is attached to the knots of the veneers.