JPH0383602A - Powder decorative veneer - Google Patents

Abstract

PURPOSE:To cover a flaw of the surface such as a crack of material and knotting and to apply a stereoscopic pattern to core material by applying powder to at least single face of core material made of veneer via an expandable polyurethane resin-based adhesive combined with thermosetting. CONSTITUTION:An expandable polyurethane resin-based adhesive 2 combined with hydrosetting and thermosetting is applied to the surface of core material 1 at about 100 g/m<2> applied amount. While a solvent contained in the adhesive 2 is not scattered after applying the urethane resin-based adhesive 2, dry wood flour 3 generated by wood sanding operation is spread on the applied face of the urethane resin-based adhesive 2. Wood flour 3 is penetrated into the adhesive 2 by pressurizing wood flour 3 by a roller. Then a plastic film 5 for mold release is covered and thermally-pressed to expand and solidify urethane resin. Thereafter it is cooled and the surface is finished by sandering.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a powder-covered plywood that can be used for decorative plywood such as plywood pasting, printed paper pasting, etc., or for construction materials such as furniture materials and flooring materials. It is.

[Prior Art] Conventional plywood uses good quality lauan wood produced from tropical rainforests to attach tissue paper, veneer, etc. Therefore, the surface of the plywood was smooth, and the smoothness of the surface did not pose any particular problem.

However, in recent years, the protection of tropical rainforests has become an issue, making it difficult to obtain high-quality lauan wood, and the price of lauan logs has also increased. Therefore, softwoods such as Japanese pine, Yonetsuga, and New Zealand pine are used because they are cheap, grow quickly, and have a short regeneration cycle, but these woods suffer from cracks, knots, and deterioration of the wood surface during the process of processing into plywood. It has several drawbacks, which limit its use.

[Problems to be Solved by the Invention] This invention solves the problem of cracks, knots, and bad plywood by adding a three-dimensional pattern with powder to at least one surface of the plywood. To provide a powder-covered plywood that completely covers the skin, has a wide range of uses, has a long service life, and is inexpensive.

[Technical Means for Solving the Problems] In order to solve the above problems, the powder-clad plywood of the present invention is made by bonding at least one side of the plywood core with water and a thermosetting foamable polyurethane resin adhesive. It has a powder coated structure.

[Function] At least one side (front or back side or both sides) of the plywood core material is coated with powder via water and a thermosetting foamable polyurethane resin adhesive, so the core material will not crack or crack. Even if you have loose knots or bad skin, these will be completely covered up.

Example 1 The core material 1 made of Japanese pine plywood shown in Figs. 1 and 2 is made of plywood material and a veneer on the surface. The board has 3 widths and 1000 lengths.
There are cracks and grooves of about 1.5mm in diameter, and the veneer is made of Japanese pine plywood with rough texture and rough texture. A foaming polyurethane resin adhesive (hereinafter also referred to as urethane resin adhesive) 2, which will be described later and can be used for both water-curing and thermosetting, is sprayed onto the surface of the core material 1 to a thickness of approximately 100%.
It is applied with a coating amount of q/m2, and after the application of the urethane resin adhesive 2, the dry wood powder 3 generated by the wood sanding operation is applied before the solvent contained in the adhesive 2 is scattered. The wood powder 3 is pressed against the surface by a roller to bite into the urethane resin adhesive 2. Then, by removing the excess wood powder 3 by vacuum suction, a relatively smooth material surface can be obtained. Next, apply a mold release plastic film (a mold release agent may also be used) as shown in Figure 3 on this material surface.
5 and insert it into the hot press machine until the surface temperature is about 100~100℃.
110℃ hot plate mold, wooden mold, etching plate) 6 to 5
Heat press for a minute. The pressure of hot pressing varies depending on the degree of density of the material surface, but in Example 1 it is about 1 ONg/7. In addition, in FIG. 3.4, 4 indicates a foam in which the urethane resin adhesive is solidified while being foamed by water or heat.

After heat-pressing, the material is cooled and the surface is sanded to create powder-covered plywood. Its main properties are shown in the table below.

Peel strength and infiltration state ◎ mark: No abnormality Example 2 As in Example 1, a water-curing and thermosetting urethane resin adhesive 2 was applied to a core material 1 made of Japanese pine plywood using a roll coater. The coating amount is 200 to 300 g/m2. Several times the same wood powder as in Example 1 was applied to the coated surface, and after removing the excess wood powder by vacuum suction, a mold with a picture pattern was immediately placed on the wood powder and inserted into a hot press. The heat and pressure conditions are a mold surface temperature of 10
Hot pressing was carried out for 10 minutes at a pressure of 0 to 110°01 and a surface pressure of 20 to 40 KI/ci.

When the mold was removed after heat-pressing was completed, an uneven pattern was created with no cracks, knots, or rough skin.

Note that silicon molds, urethane molds, and iron molds were used as the molds, but the number of times they could be used was 10 to 20 times for both the silicon molds and the urethane molds, and infinite times for the iron molds.

Example 3 In the same manner as in Example 1, a urethane resin adhesive 2 with both water-curing and thermosetting properties was applied to a core material 1 made of Japanese pine plywood using a roll coater. Wood flour was sprinkled several times on the coated surface in the same manner as in Example 1, excess wood flour was removed by vacuum suction, a veneer sliced end plate was immediately placed on the surface, and the end plate was inserted into a hot press. Heat and pressure conditions are mold surface temperature 100-110℃, surface pressure 10-30/cm
Hot pressure was applied for 10 minutes. When the mold was removed after hot pressing, the veneer slices were completely adhered to each other and a plywood board with a smooth surface was obtained.

Example 4 Powder-covered plywood was manufactured in the same process as in Example 1, using wet wood flour instead of the dry wood flour in Example 1. The moisture content of the wet flour is 30% and 85%. Powder-covered plywood made using this wet wood flour was tested in the same manner as in Example 1. As a result, powder-covered plywood with a smooth surface similar to that of Example 1 was obtained.

Example 5 Using the same core material 1 as in Examples 1 to 4, powder was mixed into the urethane resin adhesive 2 in a volume ratio equal to or higher than that, and the powder was applied to the top surface of the core material 1 at an amount of about 200 to 300 g/m2. By applying the coating thickly and using the same working process and molding material as in Example 2, a plywood surface with a three-dimensional pattern was obtained.

Example 6 In Examples 1 to 5, the moisture in the core material 1 is vaporized, and the vaporized moisture acts on the urethane resin 2 to promote the reaction, but materials that are difficult to heat, such as PVC tiles and sheets, are It is possible to bond the core material 1 at room temperature simultaneously with the mounting.

That is, when the powder-covered plywood of Example 3 is produced by the cold pressing method, water is sprayed onto the surface of the core material 1 to increase moisture on the surface of the core material, or wet wood flour is used as in Example 4. do. The amount of urethane resin adhesive 2 applied is 150 to 300 l/m2.
One set consists of spreading wood powder on the resin-coated surface, removing excess wood powder, and then placing a PVC sheet on top of the wood powder.

20 sets of these were piled up and pressed at room temperature at a pressure of 2 kg/cr11. As a result of allowing this to stand for 24 hours, the vinyl chloride sheet had excellent water resistance without secondary foaming during heat drying, and results equivalent to Examples 1 to 5 were obtained.

In each of the above embodiments, the foamable polyurethane resin adhesive that can be used for both water-curing and thermosetting is a prepolymer obtained by converting polymethylene phenyl polyisocyanate and polyoxyalkylene ether into polyurethane. The alkylene oxide of the polyoxyalkylene ether includes an oxide having 2 to 4 carbon atoms, such as ethylene oxide (EO).
, propylene oxide (PO), butylene oxide (
There are one or two types of BO), but a prepolymer in which the ratio of an addition mixture of ethylene oxide and propylene oxide is 515 to 8/2 and 12 to 29% of the remaining NGO is subjected to a polyurethane reaction is preferable.

The properties of this type of polyurethane resin adhesive related to the above embodiments are that it has both the properties of thermosetting resins such as phenol and melamine resins and thermoplastic resins such as vinyl, polystyrene, and ABS resins. By utilizing this property, a wide variety of uses can be opened up. That is, (a) the foaming pressure of the polyurethane resin is 100 to 300
Since it has a low g/ci, it can be molded using silicone resin molds with rubber elasticity.

(b) By mixing the polyurethane resin and powder, the polyurethane resin film can be made thinner, which makes the bubbles smaller and more uniform.

(c) Since it is thermosetting, it can withstand heat adhesion of veneer boards, printing paper, etc. during secondary processing up to 120°C, and there is no secondary foaming due to secondary heating.

Although wood flour was used as the powder in the above embodiments, organic and inorganic powders such as resin balloon powder, perlite powder, carbonized powder, clay, etc. can be used in addition to wood flour.

Particle sizes ranging from several microns to coarse powder of about 2 mesh can be used. Therefore, by selecting these powders according to the purpose, it is possible to freely produce powder-covered plywood having flame retardant properties, soundproofing properties, heat insulation properties, electrical insulation properties, etc.

[Effects] Since the present invention has the above configuration, it has the following excellent effects.

(b) Even if the core material is plywood with cracks, loose knots, and poor texture, by adding a three-dimensional pattern to the core material, the cracks, loose knots, and poor texture of the core material can be completely covered up. An inexpensive powder-coated plywood with a long service life and a wide range of uses can be obtained.

(b) Since organic and inorganic powders such as wood powder, resin balloon powder, perlite powder, carbonized powder, and clay can be used as the powder, a wide variety of uses can be opened up.

(C) Synthetic resin-based adhesives are used, and since these are easily available, powder-covered plywood can be mass-produced.

[Brief explanation of drawings]

FIG. 1 shows a cross-sectional view of a plywood core material coated with adhesive and powder sprinkled thereon. FIG. 2 shows an enlarged view of the state shown in FIG. 1 when it is hot-pressed. FIG. 3 is a sectional view showing the relationship between the core material, powder, and urethane resin adhesive during the hot pressing shown in FIG. 2. 1...Plywood core material 2...Water, thermosetting foamable polyurethane, urethane resin adhesive 3...Powder wood powder> 4...Foam

Claims (1)

[Claims] Powder-covered plywood characterized in that at least one side of a plywood core material is coated with powder via water and a thermosetting foamable polyurethane resin adhesive.