JPH10305529A - Decorative plywood - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a decorative plywood having excellent flaw resistance and beauty. SOLUTION: The decorative plywood comprises a woody core material, prepreg adhesive sheet, and a woody surface material. The prepreg adhesive sheet contains a base material and 100 to 200 wt.% of thermosetting resin impregnated into the base material. Excess resin flow rate at the time of heating pressure molding to represent a semicured state of the resin is 5 to 30 wt.% of the impregnated resin amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a decorative plywood comprising a wood surface material, a prepreg adhesive sheet and a wood core material.

[0002]

2. Description of the Related Art Conventionally, in the production of decorative plywood, an adhesive such as melamine resin, DAP resin, or vinyl acetate is applied to the surface of plywood as a base material, and natural wood as a surface material is cut on the plywood. It was done by sticking together a sticky board. However, in this method, it takes a long time to apply the adhesive, and furthermore, setting the attachment plate in a predetermined place has to rely on manual labor, and it is difficult to machine. In addition, it is difficult to control the penetration of the resin into the attached plate, and when it is excessive, there is a disadvantage that a resin uneven pattern is easily generated.

[0003] A method of using a prepreg sheet containing a resin for bonding is already known. However, in a decorative plywood obtained by laminating a thin plywood obtained by shaving a natural tree and a plywood serving as a base, the prepreg used depends on the prepreg used. It turned out that there is a marked difference in the finished physical properties. For example, when the amount of the resin contained in the base material is small, the adhesive force is weak, and when a force for peeling off the attached plate acts, peeling occurs. On the other hand, if the amount of the resin is too large, excess resin flows out from the side of the plate, resulting in soiling of the press machine and impairing economic efficiency. If the amount of resin contained is large and the degree of semi-curing of the resin is too sweet, the resin will be stuck to the cutting blade when cutting the prepreg sheet, making it impossible to cut cleanly, and penetrating into the board at the time of bonding and reaching the surface The penetrating resin becomes a mottled pattern and significantly impairs aesthetics.

[0004]

As a result of various investigations to control these phenomena, there is an optimum range for determining an appropriate amount of resin and the degree of the effect, and the heat and pressure molding for expressing the range is performed. It has been found that the optimum range can be defined by the concept of excess resin flow rate (hereinafter referred to as flow rate). It has been confirmed that these optimum ranges are almost common phenomena irrespective of the type of thermosetting resin used. Thus, the present inventors have succeeded in obtaining a decorative plywood having excellent scratch resistance and cosmetic properties as described below.

[0005]

That is, the present invention relates to a decorative plywood in which a wooden core material, a prepreg adhesive sheet, and a wooden surface material are laminated, wherein the prepreg adhesive sheet comprises a base material,
It is made of a thermosetting resin of 100 to 200% by weight based on the weight of the base material impregnated in the base material, and the flow rate at the time of heating and press molding indicating a semi-cured state of the resin is 5 to 30% by weight of the amount of the impregnated resin.
Decorative plywood.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, as a base material of a prepreg adhesive sheet, an inorganic fiber non-woven fabric, a synthetic fiber non-woven fabric and the like are suitable, but when a glass fiber non-woven fabric is used, particularly excellent scratch resistance can be obtained. Phenol resin, melamine resin, DAP resin, epoxy resin and the like are suitable as the thermosetting resin impregnated in the base material. The amount of the thermosetting resin to be contained is preferably 100 to 200% by weight based on the basis weight of the substrate. If the amount of the resin is less than 100% by weight, the adhesiveness is reduced, and if it exceeds 200% by weight, the amount of the protruding resin increases, which causes stains on the press device.

[0007] The flow rate at the time of heat and pressure molding, which represents a semi-cured state, is preferably 5 to 30% by weight. And develop surface hardness. When the flow rate is less than 5% by weight, the adhesive strength is poor. On the other hand, when the flow rate exceeds 30% by weight, not only does the amount of ineffective resin extruded increase, but also the adhesiveness tends to deteriorate. The flow rate is adjusted by controlling the degree of drying and the temperature in the drying step after the impregnation and controlling the curing level of the resin. Due to the surface hardness and the reinforcing effect of the prepreg adhesive sheet substrate of the present invention, the deformation resistance when a heavy object is put on is also improved. As a scratch resistance when an impact force is applied, there is a steel ball drop test, which can be evaluated by the depth of a dent after dropping.

[0008] Examples of the wood surface material used in the present invention include, for example, an attached plate obtained by shaving a natural tree into a thin sheet. Examples of the wood core material include wood plywood.

[0009]

The present invention will be described in more detail with reference to the following examples.

(Example 1) A glass fiber was formed into a sheet by a wet papermaking method, and an acrylic binder was applied so as to be 10% by weight of the sheet and dried.
A ^second glass fiber nonwoven fabric, impregnated with a phenolic resin varnish and dried to obtain a dry resin weight 150 g / m ² adhered prepreg adhesive sheet. Drying was performed with a hot-air dryer at 105 ° C., and in order to adjust the degree of semi-curing, the flow rate during hot press molding was measured, and the drying time was adjusted so that the value became 25%. Here, the flow rate refers to the above prepreg adhesive sheet in a hot press at 150 ° C. and 66 kg / c.
After pressing under a pressure of m ² for 2 minutes, the amount of extruded resin was measured, and the value was obtained from the ratio to the amount of resin contained before pressing.

[0011] The prepreg adhesive sheet having a thickness of 0.3
mm wood was sandwiched between a thinly ground board and a 12 mm thick plywood, and bonded by a hot press set to a temperature of 150 ° C. at a pressure of 10 kg / cm ² . In order to examine the scratch resistance of the surface of the decorative plywood thus obtained, the diameter was 50 m.
A steel ball having a weight of 500 g and a weight of 500 g was dropped on a decorative plywood from a height of 1 m, and the depth of the formed dent was measured. The depth of the depression from the surface was 0.3 mm, showing good results.

(Example 2) A sheet of carbon fiber was formed by a wet papermaking method, an acrylic binder was applied to a weight of 15% by weight of the sheet and dried to obtain a sheet having a basis weight of 50 g / m ² . This sheet is impregnated with an epoxy resin varnish and dried in a semi-cured state to obtain a dry resin amount of 55 g / m 2.
² A prepreg adhesive sheet was obtained. Drying conditions were selected, and the degree of semi-curing was adjusted so that the flow rate at the time of heating and pressing was 10%. This prepreg adhesive sheet,
It was used as an adhesive sheet in the same manner as in Example 1 to obtain a decorative plywood. When the same test as in Example 1 was performed on this decorative plywood to examine the scratch resistance, the depth of the dent from the surface was 0.1 mm.
Good results were shown at 23 mm.

(Comparative Example 1) The same operation as in Example 1 was performed except that the degree of semi-curing was adjusted by the temperature and time during drying of the prepreg so that the flow rate at the time of heat and pressure molding was 2%. A decorative plywood was obtained. This decorative plywood had weak adhesion to the plywood and easily peeled off when a peeling force was applied. When the scratch resistance was examined in the same manner as in Example 1, the result was that the depth of the depression from the surface was inferior at 0.6 mm.

Comparative Example 2 The same operation as in Example 1 was carried out except that the degree of semi-curing was adjusted by the temperature and time during prepreg drying so that the flow rate at the time of heat and pressure molding was 50%. A decorative plywood was obtained. In this decorative plywood, the resin flowed out heavily to the side from the boundary between the plywood and the plywood. In addition, bleeding to the surface occurred, resulting in a significant loss of aesthetics.

Comparative Example 3 A decorative plywood was prepared in the same manner as in Example 1 except that the amount of the thermosetting resin was 250 g / m ² as a dry resin. In the prepreg state, the excess resin became a thick film covering the surface, and after pressing, a uniform adhesive reinforcing layer was not obtained, and the scratch resistance was poor at 0.5 mm.

[0016]

As described above, according to the present invention, a decorative plywood excellent in scratch resistance and aesthetics can be formed by adjusting the resin content of the base material and the level of semi-curing of the resin to an optimum range. can do.

Claims (2)

[Claims] 1. A decorative plywood laminated with a wood-based core material, a prepreg adhesive sheet, and a wood surface material, wherein the prepreg adhesive sheet has a base material and a weight of the base material impregnated with the base material of 100 to 100%.
A decorative plywood composed of 200% by weight of a thermosetting resin, and having a surplus resin flow rate at the time of heat and pressure molding indicating a semi-cured state of the resin of 5 to 30% by weight of the amount of the impregnated resin. 2. The decorative plywood according to claim 1, wherein the substrate is a glass nonwoven fabric.