JPS6328601A - Manufacture of plywood - Google Patents

Abstract

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

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing plywood sheets.

[Conventional technology]

Conventionally, plywood has been manufactured by the following method. First, a thin sheet of dry wood veneer is passed through a spout or spreading head which applies a coat of adhesive to the top and bottom of the surface. Dry veneer sheets are alternately layered with thin sheets coated with adhesive, but it cannot be generalized,
The grain usually runs in the opposite direction of the glued laminate.

next. A wet ply pack (laminate) of veneer sheets is placed into a flat or curved mold and the mold is closed hydraulically. This puncture remains in place until the adhesive is cured by heating. The time for the pack to cure depends on the thickness and type of adhesive used. Once the adhesive has hardened, the sheet is removed from the press.

The above methods are time consuming and require expensive equipment.

This has a significant impact on the manufacturing cost of plywood.

[Problem to be solved by the invention]

The present invention aims to overcome or substantially improve the above-mentioned disadvantages.

[Means for solving the problem: To achieve the above object, the present invention provides at least two layers to be joined, applying an adhesive to at least one major surface of one of the layers, and applying an adhesive to at least one major surface of one of the layers. A method for producing a laminate comprising at least two layers bonded to each other, the method comprising the step of: bringing the adhesive into contact with the surface so that the layers are fixed to each other when the adhesive cures; applying a first adhesive having a predetermined curing time to a portion of the surface, and then applying a second adhesive having a shorter curing time than the first adhesive to the surface. A method for manufacturing a laminate, characterized in that the second adhesive holds the layer in a predetermined relative position while the first adhesive is applied to another part of the surface and cured. This is what I am trying to do.

〔Example〕

As a preferred embodiment, manufacturing of plywood sheets will be described. However, it is clear that the invention can be used to produce other laminated structures, such as sheets of cardboard or plastic.

According to the attached drawing, the plywood 10 {? (The laminate is shown schematically. The laminate 10 consists of several layers of wood veneers 11 that are joined together to form a sheet of plywood. In FIG. 1, the laminate 10 is actually not yet cured. This is a "wet" board coated with adhesive.
, 13. This adhesive strip 12.

13 are arranged between each pair of adjacent thin plates 11.

Although the adhesive strips 12, 13 are arranged alternately, other arrangements are possible for other materials.

Adhesive strip 12 is typically a low temperature curing adhesive, such as PVA.
Or made of EVA adhesive. Adhesive strip 13 is a fast curing adhesive, preferably US Georgia 30092;
Nordson Corporation, 350 Research Court, Technology Park, Norcross, Atlanta.

``Nordson J'' sold by RPORATION)
A true melt or hot melt adhesive applied with a Nordson® applicator is preferred. According to Nordson's applicators, the material properties of most true melt adhesives are improved by dissolving gases such as nitrogen dioxide or carbon dioxide into the adhesive. This photomelt adhesive can be measured.

Veneer 3+1i with gas-dissolved true melt adhesive
The adhesive foams when exposed to atmospheric pressure. This has the advantage of increasing the "open time" of the hot melt adhesive. The "open time" refers to the maximum time allowed for effective adhesion to occur between adhesive application and bonding of layers. It has been found that the true melt adhesive retains its rapid cure time and can be shortened by hot melt encapsulation.

When the layers 11 are placed in coextensive relationship, they are compressed together as shown in FIG. The strips 12, 13 have predetermined dimensions and are spaced apart such that as a result of compression the adhesive layer is substantially continuous between the two bonding layers 11. When producing standard plywood with a thickness of 1611 using a heated platen, a curing time of 8 seconds for strip 13 is sufficient. This is in contrast to the 8 minutes required with conventional equipment. Adhesive strip 13 then holds the layer in a compressed shape while adhesive strip 12 cures.

In the above embodiments, the case where a flat plywood was mainly formed was explained. If the layers 11 to be joined are compressed using a mold having forming recesses of a certain shape, a product with that shape can be manufactured.

The adhesive of strip 12 may also be thermosetting or cured by other means, such as by ultraviolet radiation.

〔effect〕

The preferred embodiment of the invention described above has the advantage that expensive molds and heating equipment are not required. This saves energy consumption and reduces the capital required for plywood production. The plywood forms quickly and cleaning the adhesive applicator is greatly simplified compared to standard adhesive application equipment using thermosetting adhesives. These standard adhesive application devices require significant maintenance and upkeep costs. In contrast, when using an intumescent hot melt adhesive applicator, the applicator can be relatively easily flushed and cleaned, e.g., 10 minutes or less and only need to be done every six weeks.

[Brief explanation of the drawing]

1 is a schematic perspective view, partially cut away, of a plurality of layers bonded together to form a laminate; FIG. 2 is a schematic end view of a portion of the laminate of FIG. 1; FIG. 2 is a schematic end view of the section of FIG. 2 after the laminate has been compressed; FIG. IO...Plywood, 11...Layer to be joined, 12.13
...Adhesive strip. Patent III Person T-Cert Pte Ltd.

Claims (9)

[Claims] (1) preparing at least two layers 11 to be joined; applying adhesives 12, 13 to at least one major surface of one of the layers 11; bringing the other layer 11 into contact with the surface; A method for manufacturing a laminate consisting of at least two layers 11 bonded to each other, comprising the step of: causing said layers 11 to become fixed to each other when said adhesives 12, 13 have cured, said adhesives 12, 13 The step of applying comprises applying a first adhesive 12 having a predetermined curing time to a certain portion of the surface, and then applying a second adhesive having a shorter curing time than the first adhesive 12. 13 is applied to another portion of the surface such that the second adhesive 13 holds the layer 11 in a predetermined relative position while the first adhesive 12 cures. Method of manufacturing the board. (2) The method according to claim 1, wherein the first adhesive 12 is low temperature curable. (3) The method according to claim 2, wherein the second adhesive 13 is a heat-fusible adhesive. (4) The method according to claim 2, characterized in that the second adhesive 13 is cured by exposing it to ultraviolet light or heat rays. (5) A method according to claim 2, characterized in that said layer 11 is a thin wood board. (6) The first adhesive 12 and the second adhesive 13 are applied in the form of mutually spaced and substantially parallel strips. The method described in section. (7) The strips of the first adhesive 12 and the second adhesive 13 are arranged alternately over the width of the one layer 11. Method. (8) at least two layers of sheet material extending substantially parallel; a first adhesive 12 for interconnecting predetermined portions of said two sheets; and a first adhesive 12 for interconnecting other portions of said sheets; 2. A laminate structure comprising a second adhesive 13, wherein the second adhesive 13 has a shorter curing time than the first adhesive 12. (9) The layer 11 of the thin board agent is a thin wood board, and the first
The adhesive 12 is low-temperature curable, and the first adhesive 1
9. A laminate structure according to claim 8, characterized in that the adhesive 2 and the second adhesive 13 are arranged in strips extending between the two layers 11.