JPH0716805A - Crack prevention method for flat-grained wood - Google Patents

Abstract

PURPOSE:To obtain a flat-grain lumber in a short time while keeping the flat grain, color shade, and feeling of a wood and preventing occurrence of a crack on a flat grain surface. CONSTITUTION:An adhesive 2 is applied on the both flat grain surfaces of a sawed flat-grained wood 1. The wood 1 is heated and pressurized by a saturated steam in an autoclave. Next, the steam is discharged, and the wood is treated under reduced pressure and dried. Thereafter, the applied adhesive layer is removed. In this manner a lumber never generating a crack on its flat grain surface is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing cracks in lumber that has been sawn and sawed, and more specifically, it is possible to produce lumber products that do not have cracks in the sawn surface of sawn timber in a short period of time. Regarding how to get.

[0002]

2. Description of the Related Art When wood is used as a craft material such as building materials, fittings, furniture, and woodwork products, it is often the case that sawing is carried out in order to utilize the original wood grain. However, sawed wood products are prone to cracking, shrinkage, and deformation during use, and the prevention of these problems is a major technical issue for tree species such as Yonematsu that are prone to cracking.

The water content of 20 has long been used as a method for preventing cracks, shrinkage and deformation of lumber that has been lumbered.
It is a method of drying until it becomes less than about percent. Wood has been naturally dried since ancient times, but since it takes a long time of one year or more, recently artificial forced drying has been increasing.

As the method, in addition to the simple hot air drying or vacuum drying method, for example, the steaming vacuum method or after heating with saturated steam in a closed tank and vacuum suction, air is further sucked in another closed chamber. The method of drying the water content of the air and then recirculating the hot air to be sucked into the room for a long time (Japanese Patent Laid-Open No. 48-33001), and after steaming wood by steam injection, the atmospheric pressure is different in the closed pressure vessel. A method has been proposed in which high-pressure steam is applied in two stages and then pressure is reduced (Japanese Patent Laid-Open No. 51-151305).

[0005]

However, these methods can be dried in a shorter period of time with less generation of cracks as compared with a simple hot air drying method, etc., but when drying thick planed wood. It is not possible to sufficiently prevent cracks in the grain surface of. In addition, a method of applying paint or adhesive to the grain surface is generally used as a method of preventing cracking of grain sawn wood other than drying. , There is a drawback that the color and texture are lost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for obtaining short-cut wood in a short period of time while maintaining the original wood grain, color and texture and without causing cracks in the grain surface.

[0007]

In order to solve the above problems, the present invention applies an adhesive to both sides of a grain of sawn wood and then saturates the wood in a pressure cooker. It employs a constitution in which heating and pressurizing with steam, discharge of the steam, treatment under reduced pressure, drying, and then removal of the applied adhesive layer.

[0008]

According to the present invention, an adhesive is applied to the grain surface of sawn wood, heated and pressurized with saturated steam in a pressure cooker, and then the steam is discharged and treated under reduced pressure. After that, it is dried and then the applied adhesive layer is removed. The target woods of the present invention are various tree species without distinction between domestic and foreign conifers and broad-leaved trees, and examples thereof include Yonematsu, Todomatsu, Japanese cypress, cedar, Akamatsu, Kuromatsu, zelkova and oak.

The wood is utilized by taking advantage of the grain of wood, but in the present invention, it is limited to wood that has been grained.

The adhesive used in the present invention withstands heat treatment with saturated steam at 100 ° C. or higher for several hours, and is made of urethane resin, urea resin, melamine resin,
Adhesives such as urea / phenol resin type, urea / phenol / melamine resin type, phenol resin type, epoxy resin type and chloroprene can be preferably exemplified. These adhesives are evenly applied to both sides of the wood by a spreader.

The wood coated with the adhesive has a cylindrical pressure capable of withstanding a pressure reduction of 10 mmHg and a pressure increase of 20 kg / cm ² provided with a saturated steam inlet, an exhaust port connected to a vacuum pump, a drain waste liquid port, and a thermometer. Store in the pot. Saturated steam is put into a pressure cooker, usually 110 to 170 ° C., more preferably 120.
To 150 ℃, depending on the thickness of the wood, usually 1
The heating and pressing is performed for 5 hours, more preferably 2 to 4 hours. In this step, the adhesive layer prevents the moisture of the wood from being drained on the grain side, and consequently opens the grain side or the grain opening to drain the moisture.

Then, saturated water vapor is discharged, the vacuum pump is operated, and the pressure inside the pressure cooker is reduced to 700 mmHg or less, more preferably 200 mmHg or less, so that the water content of the wood is boiled and evaporated uniformly. After 0.5 to 3 hours, the pump operation is stopped, the pressure inside the pressure cooker is returned to normal pressure, and then the wood is taken out from the pressure cooker. Even in this step, moisture is evaporated from the grain side and the wood mouth due to the adhesive layer.

After that, the wood is dried in a natural or hot air drying or vacuum drying machine in a short period of time without cracking. The adhesive layer is removed from the wood by a cutting machine such as a planer,
It is done completely without leaving any marks using a polishing machine.

[0014]

The present invention will be described below with reference to examples and comparative examples. The occurrence of cracks during use was evaluated by the following method.

Evaluation of crack generation during use After the wood was treated in a hot air dryer at 90 ° C. for 3 days, the presence or absence of cracks was visually inspected.

Example 1 As shown in FIG. 1, a pine tree was diced into a size of 3000 mm in length, 200 mm in width, and 30 mm in thickness, and a urea resin adhesive 2 ( Product name Aika Yuri UC
After applying -120 << Aika stock >>, the wood 1 was placed in a pressure cooker. 2 kg / cm ² water vapor was sent to the closed pressure cooker, the internal temperature was adjusted to 130 ° C., and the temperature was maintained for 4 hours. Then, the saturated steam was evacuated, and the pressure cooker was left under a reduced pressure of 150 mmHg for 2 hours. Then, the pressure was returned to normal pressure, the wood was taken out of the pressure cooker, air-dried for 3 days, and then dried in a hot air dryer at 50 to 80 ° C. for 24 hours. The wood grain surface taken out from the dryer was scraped with a planer to remove the adhesive layer. As a result of evaluating the cracking property of the wood by the above method, no cracking occurred on the grain surface.

Example 2 Example 1 was repeated except that a phenol resin adhesive (trade name: Dianol TD-62 << Oshika Shinko Co., Ltd.) was used in place of the urea resin adhesive. The wood obtained by removing the adhesive layer with a planer was evaluated for cracking property by the above method, and as a result, no cracking occurred on the grain surface.

Example 3 Example 1 was repeated except that a melamine resin adhesive (trade name Oshia Resin M31 << Oshika Co. Ltd.) was used in place of the urea resin adhesive. The wood obtained by removing the adhesive layer with a planer was evaluated for cracking properties by the above method, and as a result, no cracking occurred on the grain surface.

Comparative Example 1 Yonematsu lumber, which was ground to the same size as in Example 1, was stored in a pressure cooker as it was, and 2 kg / cm ² of water vapor was fed to the closed pressure cooker at an internal temperature of 130 ° C. for 4 hours. I kept it. Then, the saturated steam was exhausted, and the pressure cooker was left under a reduced pressure of 150 mmHg for 2 hours. After that, the pressure was returned to normal pressure, the wood was taken out of the pressure cooker, air-dried for 3 days, and then the wood taken out from the hot air dryer had small cracks on the grain surface.

Comparative Example 2 A urea resin adhesive was applied to the grain surface of a pine pine lumber that was sawn in the same manner as in Example 1, and then the wood was air dried for 3 days. After that, it was dried in a hot air dryer at 50 to 80 ° C. for 24 hours. The grain surface of the wood taken out from the dryer was scraped with a planer to remove the adhesive. As a result of evaluating the crack generation property of the wood by the above method, it was found that the wood grain surface had cracks.

[0021]

As described above, according to the present invention, since the grain surface, which is easily broken, is protected by applying the adhesive, no crack is generated during drying, and moisture is prevented from the side surface, that is, the grain surface. The wood can be evaporated and dried sufficiently, and the lumber product obtained by removing the adhesive does not crack, shrink, or deform during use.

Further, the lumber product obtained by the method of the present invention is
Since there is no paint or adhesive left on the surface, it is possible to maintain the original grain of wood, the texture of the wood, the color, and the texture, and sawed wood is used for construction materials such as ceiling boards, wall materials, flooring, and other fittings. It can be used as a material for crafts such as wood products.

[Brief description of drawings]

FIG. 1A is a perspective view showing a state in which an adhesive is applied to wood, and FIG. 1B is a side view of the same.

[Explanation of symbols]

 1 Wood 2 Adhesive

Claims (1)

[Claims] 1. After applying an adhesive agent to both sides of the grain of sawed wood, the wood is heated and pressurized with saturated steam in a pressure cooker, and then the steam is discharged and treated under reduced pressure. A method for preventing cracking of sawed wood, which comprises drying and then removing the applied adhesive layer.