JPH1071608A - Wood product having its surface structure modified and method of modifying wood surface structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To modify the surface structure of a wood block but with its thickness sufficiently controlled. SOLUTION: A desired surface 10 of a wood block 1 is selected, a side surface 2 perpendicular to the selected surface 10 is irradiated with a laser beam 4 arranged in a direction parallel to the selected surface 10, so as to be subjected to in-sizing of only a portion adjacent to the selected surface 10. The holes 5 of the wood block 1 formed by the in-sizing are then impregnated and filled with a liquid resin. Finally, the liquid resin 6 is hardened and at the same time the wood portions adjacent to the selected surface 10 are compressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for modifying a surface layer of wood and a wood having the modified surface layer.

[0002]

2. Description of the Related Art In order to prevent weathering of wood, prevention of contamination, improvement of wear resistance, improvement of damage resistance, and improvement of dimensional stability, etc.,
There are (1) a method of painting the surface of wood, (2) a method of hot-pressing the entire wood, (3) a method of impregnating the surface layer with resin, and (4) a method of impregnating the entire wood with resin. .

[0003]

In the case where the surface of wood is painted (method (1)), the base material expands and contracts due to the absorption and release of moisture from the base material, and the surface coating film is not linked to this. ,
Cracking of the coating film occurs, the durability of the coating film is extremely short, and even an expensive and excellent paint requires repainting in a short period of time, and frequent maintenance is required.

[0004] When wood is subjected to a heat and pressure treatment (method (2)), there is a fundamental problem that the density of the whole wood is increased and the characteristic of wood being a light and strong material is lost. Further, the layer compressed by heat and water may be restored.

In the method of impregnating the surface layer with a resin (method (3)), the resin cannot be impregnated to a sufficient depth by merely impregnating the resin. Is often used, but it is difficult to control the depth and degree of impregnation.In addition, scars of the insizing blade remain on the surface or the surface layer There is an obvious drawback in that the digging causes scratches and damages the appearance.

[0006] In the case of impregnating a resin into the whole wood (the above method (4)), there is a problem that the treatment takes a long time and is expensive. Since cedar and redwood heartwood are inherently highly resistant to decay, they are used directly as exterior wood. However, since these woods are soft, they are deteriorated by ultraviolet rays, discolored or cracked by the action of rainwater,
Skin thinning and fluffing are likely to occur. On the other hand, since these woods are woods with poor injectability, resin injection is difficult.
As a method of injecting resin, chemicals, etc. into wood, even with the widely used vacuum pressure injection method, liquid penetrates only a few centimeters from the mouth of the wood and about 1 mm from the grain and straight grain faces. do not do. The present invention has been made to solve these disadvantages.

[0007]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems by providing a laser beam in a direction parallel to the selected desired surface of wood toward a side intersecting the surface. Irradiating only the portion of wood close to the surface by irradiating, impregnating the portion of wood close to the surface with resin through the holes formed by the insizing, and thereafter curing the resin. I will provide a.

Further, the present invention provides a method characterized in that the resin-impregnated portion, that is, the surface layer portion impregnated with the resin is compressed simultaneously with the curing of the resin.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for modifying the surface layer of wood according to the present invention, first, wood is processed into a predetermined shape, and then a desired surface (for example, a beautiful grain of wood) of the wood is determined as a surface. And irradiate a laser beam in a direction parallel to the surface toward a side intersecting the surface to penetrate the insizing hole to the side opposite to this side (the laser beam is alternated from the opposite side). :), forming such insizing holes in a plurality of layers below the surface, and then forming the surface in a resin solution (thermosetting or thermoplastic synthetic resin or natural resin). A resin portion selected from the above) is submerged to a predetermined depth for a predetermined time to impregnate the wood portion near the surface with the resin (preferably under reduced pressure or vacuum), and then the resin is cured. A wood of the desired depth is thus obtained with a precisely modified surface layer, without any insizing holes appearing on the desired surface of the wood and the aesthetic appearance is not impaired.

Further, in the second method of the present invention, the surface layer is compressed when the impregnated resin is cured. This compression is performed by a flat plate press. The wood treated in this way has a compacted surface layer and increased strength. Further, the insizing hole formed on the side surface by this compression is crushed and becomes inconspicuous.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the method for modifying wood according to the present invention will be described below with reference to the drawings. Referring to FIG. 1, a laser beam output from a laser processing machine 3 on a side surface (a grain surface or a straight grain surface) 2 which intersects a selected one surface 10 of wood 1 in a predetermined dry state at a right angle. 4 and wood 1
Is penetrated to the opposite side surface (see FIG. 1A). Thus, when one insizing hole is formed, the laser beam 4 is moved to generate another insizing hole next to the same.

By repeating the above operation, laser processing is performed so that the holes 5 for insizing are arranged near the surface 10 as shown in FIG. As the laser beam used at this time, any laser beam such as a gas laser such as a CO ₂ laser can be used. In the illustrated example, the number of layers in which the holes are arranged is two, but only the surface layer having a desired thickness has resin 6.
The number of layers can be selected according to the purpose of impregnation.

As shown in FIG. 1C, only the surface of the wood 1 is immersed in a liquid of a resin (a thermosetting resin in this embodiment) 6, and the resin 6 is applied to a wood portion close to the surface 10 of the wood 1. Impregnated. As a method for impregnating the resin, any method such as normal pressure impregnation, vacuum impregnation, and reduced pressure impregnation can be used. Preferably, however, the air in the timber 1, especially the air in the holes 5 of the insizing, is removed by vacuum impregnation, vacuum impregnation, etc., in order to promote uniform injection of the resin 6 into the holes 5 of the insizing. And then impregnated with resin. Examples of the thermosetting resin include phenol, melamine, urea, and epoxy resin. The resin may be used by diluting the resin with a volatile solvent, water, or the like in order to improve the fluidity.

As shown in FIG. 1D, the wood 1 is placed on a heated flat plate press 8 with the resin impregnated layer 7 of the wood facing down, and heated for a few minutes. At this time, the temperature of the flat plate press is set to 150 ° C. or higher. Lignin and hemicellulose, which are constituents of wood, have a heat softening temperature of 20 in a dry state.
Although the temperature is 0 ° C. or higher, the temperature drops to about 100 ° C. in a wet state, so that the resin impregnated layer 7 of the wood is sufficiently softened. After heating the resin impregnated layer 7 for a few minutes as described above, the distance bar 9
Is pressed to a predetermined press rate using the resin impregnated layer 7
And pressurized for 10 minutes or more while maintaining the press ratio. The resin 6 thus impregnated is cured to fix the consolidation. The height of the distance bar 9 depends on the degree of consolidation of the resin-impregnated layer 7, but the height of the wood is 70 to 70 mm.
90%.

After the resin is cured, the pressing pressure is gradually released, and after releasing the press, the wood 1 is taken out (see FIG. 1 (e)).
In order to completely cure the resin 6 in the wood 1, 15
30 pieces of wood 1 in a hot air dryer or the like set to a temperature of 0 ° C or higher.
Add more than a minute. Thus, wood whose surface layer is resin-impregnated and compacted can be obtained.

In the case where it is not necessary to consolidate the surface layer, the solidification may be performed immediately after the resin impregnation without using the flat plate press 8.

The following shows more specific data. Wood is Japanese cedar, Japanese cedar heartwood (L: 300 × T: 60 × R: 27
(Mm)). Fig. 2
Insizing with a laser beam so that the holes 5 of the insizing become one layer in the L direction as shown in FIG.
12, 16 mm). After sealing the edge 12 with an epoxy resin, only the insizing region (that is, the surface layer) is covered with an aqueous phenol resin solution (number average molecular weight 27).
0, non-volatile content 30%), and vacuum impregnation was continued for 2 hours (one day for normal pressure impregnation), and an aqueous resin solution was injected. After the wood was air-dried for one week, the resin-impregnated layer was heated for 3 minutes by a flat plate press at a temperature of 180 ° C., and then compressed for 10 minutes so that the thickness R became 27 mm to 23 mm. Thereafter, the wood was placed in a thermostat (temperature: 160 ° C.) for 1 hour to post cure the resin.

As shown in FIG. 3, the surface hardness (Brinell hardness) is about 90 compared to untreated wood only by the resin injection treatment.
% Increase (cedar heartwood), approximately 290% with the addition of consolidation treatment
It was increased (cedar heartwood).

Still another comparison result is shown in FIGS.
FIG. 4 shows the processing A for the cedar core material (the pitch of the insizing holes is 16 mm, one layer, resin impregnation, press length 4 m)
m), Treatment B (Insizing hole pitch is 12 m)
m, 1 layer, resin impregnation, press length 4 mm), treatment C (insizing hole pitch is 6 mm, 1 layer, resin impregnation, press length 4 mm), treatment D (insizing hole pitch is 12 mm, 1 layer) 4 shows the results of a comparison of surface hardness tests (mainly with different pitches of holes) of those subjected to treatment E (no treatment at all), resin impregnation, press length 0 mm). As can be seen, the resin impregnated and pressed has approximately the same surface hardness regardless of the hole pitch.

FIG. 5 shows treatment A (insizing hole pitch: 12 mm, one layer, resin impregnation, press length: 3 mm), treatment B (insizing hole pitch: 12 mm, two layers, resin impregnation) , Press length 6mm), Processing C
(Insizing hole pitch is 12 mm, 3 layers, resin impregnation, press length 9 mm), treatment D (Insizing hole pitch is 12 mm, 2 layers, resin impregnation, press length 0 m)
m) shows the results of a surface hardness test comparison (mainly with different press lengths) of the treated E (no treatment at all). As can be seen from the graph, the surface hardness of the resin-impregnated and pressed material increases due to the increase in the press length.

FIG. 6 shows treatment A (insizing hole pitch: 16 mm, one layer, resin impregnation, press length: 3 mm), treatment B (insizing hole pitch: 12 mm, one layer, resin impregnation) , Press length 3mm), Processing C
(Insizing hole pitch: 6 mm, 1 layer, resin impregnated, press length: 3 mm) Change in lightness of wood surface by outdoor exposure test (3 months) of treatment D (no treatment at all) (ΔL: JIS Z8729) -How to display 94 colors-
L ^* a ^* b ^* color system and L ^* μ ^* ν ^* system). As can be seen, woods A, B, C treated according to the invention
The change in the lightness of the surface is small and slightly changed to dark black, whereas that of the untreated wood D largely changes to white.

FIG. 7 shows the change in the color of the wood surface (ΔE: color difference display method according to JIS Z8730-80) in the outdoor exposure test (3 months). 7 is a comparison result of processes A to D similar to FIG. As can be seen, the change in the color of the surface of the wood D is remarkable as compared with the change in the color of the surface of the wood A, B and C treated in the present invention. In addition, this outdoor exposure test (3
), The wood treated by the present invention hardly deteriorated due to ultraviolet rays or rainwater.

FIG. 8 shows treatment A (insizing hole pitch: 12 mm, one layer, resin impregnation, press length 3 mm), treatment B (resin impregnation, press length 3 mm) for Japanese cedar,
The thickness change by the boiling test of the thing which processed C (only press length 3mm was given) is shown. As can be seen from these results, the resin-impregnated and consolidated wood has a small change in thickness even in the boiling test.

FIG. 9 shows the surface area of the cedar treated with A (insizing hole pitch: 12 mm, one layer, resin impregnated, press length: 3 mm), and treated B (no treatment at all) by a water immersion test. Indicates a change. As can be seen from these results, the wood impregnated with the resin and the consolidation treatment have a small swelling coefficient of the surface layer area even in the water immersion test, and the dimensional stability is improved.

[0025]

According to the present invention, only the desired surface layer of wood is laser-insulated from the side surface, so that no insizing marks appear on the surface of the surface layer, and the resin is evenly distributed on the surface layer. Impregnated. Then, at the same time as the surface layer portion of the wood is compacted, the insizing holes on the side surfaces are crushed, and the insizing traces on the side surfaces become inconspicuous. And since the resin of a surface layer part is hardened | cured, the surface layer modified wood which the surface layer part does not restore by heat and water is obtained.

By applying the present invention to wood that is inherently durable, such as cedar and redwood heartwood, the surface layer of the wood is compacted and fixed with resin.
Hard and light exterior wood with improved surface hardness and weather resistance, preventing deterioration due to ultraviolet rays and discoloration, cracking, skin thinning and fluffing due to rainwater, as well as improved surface wear resistance and damage resistance be able to.

In the surface-modified wood according to the present invention,
Even if the surface is painted, since the surface layer is fixed with resin, the dimensional stability of the base wood is improved, the coating does not crack, and the durability of the coating becomes extremely long. No need for frequent maintenance. In addition, since the surface portion is treated with a resin without coating, it is possible to prevent mold contamination on the wood surface and dirt of green algae.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a series of steps of a method for modifying a surface layer of wood according to the present invention.

FIG. 2 is a perspective view of wood for explaining an embodiment of the present invention.

FIG. 3 is a graph comparing the surface hardness of wood modified by the method of the present invention with the surface hardness of untreated wood by a graph.

FIG. 4 is a graph showing the results of testing the change in surface hardness of wood modified by the method of the present invention with insizing hole pitch.

FIG. 5 is a graph showing the results of testing the change in surface hardness of wood modified by the method of the present invention with press length.

FIG. 6 is a graph showing a change in lightness of a wood surface as a result of an outdoor exposure test of wood modified by the method of the present invention.

FIG. 7 is a graph showing a change in color of a wood surface as a result of an outdoor exposure test of wood modified by the method of the present invention.

FIG. 8 is a graph showing the results of testing the thickness variation due to boiling of wood modified by the method of the present invention.

FIG. 9 is a graph showing the results of testing the change in surface area due to water immersion of wood modified by the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wood 2 Side surface 3 Laser processing machine 4 Laser beam 5 Insizing hole 6 Thermosetting resin 7 Resin impregnation layer 8 Flat plate press 9 Distance bar 10 Desired surface selected from wood 12 Kiguchi

Claims (3)

[Claims] 1. A method for irradiating a desired surface of wood with a laser beam in a direction parallel to the surface toward a side surface intersecting the surface, thereby insizing only a portion of the wood close to the surface, A method for modifying a surface layer of wood, comprising impregnating a resin in a wood portion close to the surface through a hole formed by sizing, and thereafter curing the resin. 2. A method of irradiating a desired surface of wood with a laser beam in a direction parallel to the surface toward a side surface intersecting the surface, thereby insizing only a portion of the wood close to the surface, The wood surface near the surface is impregnated with resin through the holes formed by sizing, and thereafter, the resin is cured and, at the same time, the wood portion near the surface is compressed, thereby modifying the surface layer of the wood. Method. 3. Wood having a surface layer modified by the method according to claim 1 or 2.