JPH0639814A - Manufacture of collected pulpwood for plywood - Google Patents

Abstract

PURPOSE:To attempt effective use of wood resources as well as elimination or reduction of labor and economizing of energy in manufacture of plywood by providing an industrially useful method for collecting a plurality of pieces of small diameter wood to make a large diameter. CONSTITUTION:Collected pulpwood for plywood is manufactured as follows; a moisture setting isocyanate adhesive of 1.0-25.0wt.% isocyanate content is applied to a surface of a plurality of pieces of small diameter wood 2 treated by softening with steam at 80-100 deg.C; after casting into a compression treating machine 3, they are compressed so that compressibility of the small diameter wood 2 (total in sectional area of the small diameter wood after compaction divided by total in sectional area of the small diameter wood before compaction mu100) becomes 60-70%; a plurality of pieces of the small diameter wood 2 are bonded with each other to be integrated and besides, a moisture content in the small diameter wood 2 is uniformalized; after the adhesive has been thoroughly hardened as they are compacted, their deformation is fixing processed for 10min or longer again with steam at 80-100 deg.C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is directed to improving the yield of raw wood, saving labor, and increasing the diameter of small-diameter wood that was not previously suitable for plywood production.
The present invention relates to a method for manufacturing laminated wood for plywood that can save energy.

[0002]

2. Description of the Related Art In recent years, depletion of South Sea wood has become a real problem, and it is becoming increasingly difficult to obtain raw wood. Along with that, the diameter of the available raw wood is gradually reduced, and the ratio of the cores produced after cutting by the rotary race is increased, resulting in a decrease in the yield of the veneer.
In addition, the obtained veneer also has a problem that the ratio of the narrow veneers as a whole increases and the number of steps required for production such as joining increases more than ever and the productivity decreases.

As a method for solving such a problem, it has been studied to improve the rotary lace machine so that the diameter of the core removed after cutting in the rotary race is as small as possible, but this method slightly improves the yield. It was not a fundamental solution.

On the other hand, utilization of so-called laminated raw wood, which is used as a raw wood for plywood by subjecting a small-diameter tree to a large-diameter treatment, has been studied. For example, a method of bundling small-diameter trees and filling and adhering a filling material in a space formed between the obtained virtual circumscribed cylindrical shape and each small-diameter tree to obtain a composite raw wood (Japanese Patent Laid-Open No. 56-7090).
No. 2), a method of applying an adhesive to the outer peripheral surface of a large number of small-diameter trees, compressing it to cause deformation, and adhering to increase the diameter (Japanese Patent Publication No. 4-4). Has been done.
Of these methods, the latter is a method that combines the conventional laminated wood technology and the conventional wood plastic processing technology and is an effective method for solving the above problems.

With respect to plastic working of wood, it is known that when heated, saturated wood is subjected to compressive strain and then immediately unloading, the strain is almost recovered, and this strain is applied to restrain this deformation. The deformation is fixed as it is when it is dried, but even in that case, it is said that it recovers when it is again affected by moisture and heat (Yosendo published: New Wood Engineering, Kanji Nakato, “29. Plastic processing”). ). Then, in order to permanently fix the deformation of the wood, a method of injecting a water-soluble phenol resin initial condensate, a dry state at 180 to 220 ° C.
High temperature, high pressure and special equipment such as a method of heat treatment for about 15 hours and a method of treatment with steam at 160 to 200 ° C. for 1 to 8 minutes have been required.

It has been known for a long time that a moisture-curable adhesive is preferable as an adhesive suitable for adhering timber in a water-saturated state. However, in order to use it in the production of laminated log, individual small diameter It is not easy to select an adhesive that has the required speed and strength due to the fact that the water content of wood varies greatly and that it is necessary to apply the adhesive to a large area and high temperature wood surface. It was

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for industrially easily manufacturing a laminated log for plywood from a plurality of small-diameter trees. Further, secondly, it is an object of the present invention to use the above laminated wood for plywood to save labor and energy in the manufacturing process of plywood.

[0008]

According to the present invention, 80-1
After applying a moisture-curable isocyanate-based adhesive having an isocyanate group content of 1.0 to 25.0% by weight to the surfaces of a plurality of small-diameter trees softened by steam at 00 ° C. and introducing them into a compression processor, the small-diameter trees Compression rate (total cross-sectional area of small-diameter trees after compaction / total cross-sectional area of small-diameter trees before compaction x 100) is 60 to
After the pressure is reduced to 70%, the small-diameter trees are adhered and integrated with each other, the water content in the small-diameter trees is made uniform, and the adhesive is sufficiently cured in the pressed state, and then 80 to 10 again.
There is provided a method for producing laminated lumber for plywood, which comprises fixing the deformation with steam at 0 ° C. for 10 minutes or more.

That is, in order to produce a laminated log for plywood from a small diameter tree containing water, the isocyanate group content is 1.0 to 2
A 5.0% by weight moisture-curing type isocyanate adhesive is particularly suitable, and when it is pressed so that the compressibility becomes 60 to 70%, excess water inside the small-diameter tree is removed and the moisture content of the whole is reduced. It is possible to obtain laminated raw wood with little variation between parts, and 80 to 10 that does not require a pressure vessel.
The present inventors have found that the deformation is fixed when treated with steam at 0 ° C. in a compressed state, and the present invention has been completed.

In the present invention, any small-diameter tree can be used regardless of the tree species and the place of origin, and examples thereof include thinned wood, cores of raw wood, and small-diameter logs. Further, the small-diameter tree herein means a wood having a small diameter, but even a tree having a diameter that can be cut by a rotary race can be used because the production efficiency is further improved by increasing the diameter by the method of the present invention. These small diameter trees contain a large amount of water because they are stored in a storage area, but in the present invention, the small diameter trees are used with a high water content.
Further, in use, it is particularly preferable to manufacture the laminated raw wood from small-diameter trees of the same tree species.

Isocyanate group content is 1.0 to 25.0
The weight-% moisture-curable isocyanate-based adhesive means an isocyanate group-containing urethane prepolymer of a polyisocyanate such as diphenylmethane diisocyanate, m-xylylene diisocyanate, and toluene diisocyanate and a polyol, or a prepolymer of the above polyisocyanate. Isocyanate group content is 1% by weight
If it is less than less than 50%, not only the adhesive strength becomes insufficient but also the adhesion speed becomes slow, so that the isocyanate group content is 25 or less.
If the content exceeds 10% by weight, a large amount of carbon dioxide gas is generated by the reaction between the isocyanate group and water, the adhesive layer is foamed, and the adhesive strength is rather lowered, which is not preferable, and the isocyanate group content is 7.0 to 20.0% by weight. Is particularly preferable.
The above isocyanate-based adhesive is not preferable because it cures while being applied to the surface of a small-diameter tree, or conversely, if the time required for curing is too long, it causes adhesion failure. 0.01 to 1.0% by weight of curing accelerator
It is preferable to use the one in which the open time and the adhesion speed are adjusted by addition. In the case of the present invention, it is particularly desirable that the open time is in the range of 0.5 to 2.5 hours. As a method of adjusting the open time and the adhesion speed, an isocyanate adhesive is also used as a two-component type composed of a main agent and the above curing accelerator, and each is separately applied and both are brought into contact with each other during pressing to cure. Examples thereof include a method, microencapsulation of the above curing accelerator, addition to an isocyanate-based adhesive, and destruction of the microcapsules by the pressure during compression to initiate curing.

The method of manufacturing the laminated log 1 for plywood according to the present invention will be specifically described below with reference to the drawings. First,
The plurality of small-diameter trees 2 described above are softened with steam at 80 to 100 ° C. The inside of the small diameter tree 2 is softened by 80 to 100
Up to ℃ (usually 30 per inch radius)
It takes about a minute. ). Then, after applying the moisture-curable isocyanate adhesive to the surface of the softened small-diameter tree 2, it is put into the compression processor 3 and pressed. It is necessary to make the fiber directions of the small-diameter trees 2 the same in the method of charging the compacting machine 3, and it is preferable to bundle them in order to efficiently charge them. The press board 31 of the compression processor 3 is preferably curved so that the laminated raw wood 1 having a cylindrical shape can be obtained. In addition, the compaction is in a state in which the small diameter tree 2 can be softened (80 to 100 ° C).
Is maintained), and the pressure is usually around 10 kg / cm 2 because the small diameter tree 2 is softened.

In the compression step, it is preferable to compress and deform the compression rate to about 60 to 70%. When the compression rate is in the above range, even if the water content of the individual small diameter trees 2 is significantly different, the wood is compressed. It was found that the excess water inside was removed to obtain laminated log 1 with less variation in water content. Theoretically, it is possible to compress and deform wood up to a compression rate of about 40%, but if the compression rate is less than 60%, the yield will be reduced against the purpose, and it will be necessary to press at high pressure. There is a problem, and when the compressibility exceeds 70%, the moisture content varies greatly depending on the part of the laminated log 1 obtained, and the thermal efficiency in the dryer process deteriorates, and the pressure on the surface of the small diameter tree 2 also becomes insufficient, causing adhesion. Not enough strength. Further, when the compression ratio is 80% or more, voids are easily formed in the obtained laminated log 1 and a continuous veneer cannot be obtained, which is not preferable.

The pressing is carried out after the small diameter tree 2 is deformed and increased in diameter as described above, and then held until the isocyanate adhesive is sufficiently cured, and then, again in the pressed state, at 80 to 100 ° C.
Deformation is fixed for 10 minutes or more with the steam of. The isocyanate-based adhesive reacts with the water contained in the wood to cure while foaming and at the same time reacts with the hydroxyl groups in the wood to firmly bond the small diameter trees 2 to each other, but the curing is not sufficient. Immobilization treatment with steam in this state is not preferable because the final adhesive strength will be insufficient.This is probably because the reaction between the isocyanate group and water occurs preferentially and the reaction with the hydroxyl group in wood does not occur much. Be done. When the pressure is released without performing the fixing treatment, it immediately expands and is not usable as the log 1 because of cracks or peeling of the adhesive portion. In addition, it was necessary to fix the deformation of wood at a fairly high temperature and high pressure, but as a result of experiments, it was possible to use at normal pressure 80-100 ° C.
It was found that treatment with water vapor for 10 minutes or more could sufficiently immobilize it and the original state could not be restored even if left for a long time.

After the fixing treatment, the pressed state is released to obtain the laminated log 1 for plywood of the present invention. The raw wood 1 thus obtained is made into a single plate by a rotary race used in a conventional plywood factory, and can be laminated and adhered after drying to obtain a plywood.

[0016]

EXAMPLES The present invention will be described in detail below with reference to examples. Reference example In order to investigate the smoothing effect of water content by compaction, small-diameter trees with different water content (water content 60-120%) (diameter 20-3
(5 cm, length 1 m) is softened by steam at 80 to 100 ° C. for 6 hours, and then compressed to a predetermined compression ratio (5 each).
After pressing and cooling to 80 to 100 ℃
The sample was fixed for 40 minutes with water vapor, and the change in water content and its standard deviation were measured. The results are shown in Table 1. From the results of Table 1, it can be seen that when the compressibility is 70%, the water content is considerably smoothed, but when the compressibility is as low as 85%, it is not so effective.

[0017]

[Table 1]

Example 1 As a small-diameter tree, the peeled water content was 96% and the diameter was 43%.
cm, 1 m white lauan, water content 110%, diameter 32 cm, 1 m white lauan 1 water content, 82% water content, 38 cm diameter, 1 m red lauan 1 water content, and water content 7
9 to 114%, 15 cm diameter and 1 m long white lauan peeling cores were placed in each heating container, and 100
A steam at a temperature of ℃ was introduced and a softening treatment was performed for 4.5 hours. Then, immediately on the surface of each small diameter tree, an isocyanate-based adhesive (trade name: Konishi Bond KU-224 (manufactured by Konishi Co., Ltd.), open time 2.0 hours (isocyanate group content 16.
4%, diphenylmethane diisocyanate adhesive))
Was sprayed with 200 g / m 2 and then put into a compression treatment machine and fixed by pressing at a pressure of 10 kg / cm 2 until the compression rate became 70%. At this time, a large amount of water exuded from the wood.
After pressing, leave the adhesive as it is for 3 hours to completely cure the adhesive.
The deformation was fixed by introducing steam at 00 ° C. and heating for 40 minutes. Thus, a laminated log for plywood having a diameter of 64 cm and a length of 1 m was obtained. This laminated raw wood was cut by a rotary race to produce a veneer, but the veneer had a water content of 60 to 96%, which showed extremely little variation in water content compared with the original timber, and the drying process could be saved. . In addition, even if this laminated log was left outdoors or immersed in water, the deformation was not recovered.

Comparative Example 1 Small diameter tree 10 having various diameters and a water content of 60 to 110%
A laminated log was obtained by processing the book in the same manner as in Example 1 except that the fixing process for deformation was omitted. At the same time as the compression was released, expansion started due to the recovery of deformation, many cracks and gaps were formed, and plywood was formed. It could not be used as an integrated log.

Comparative Example 2 Small diameter tree 10 having various diameters and a water content of 60 to 110%
A laminated raw wood was obtained by the same procedure as in Example 1 except that the book was left for 30 minutes after pressing and was fixed before the adhesive was completely cured. It was enough and it fell apart during cutting in a rotary race.

Comparative Example 3 Coronate 3053 (isocyanate group content 28
%, Diphenylmethane diisocyanate adhesive (manufactured by Nippon Polyurethane Industry Co., Ltd.), to which 0.2% of dibutyltin dilaurate was added as a curing accelerator, was used as an isocyanate adhesive (open time 1.0 hour), and a small diameter tree was prepared beforehand. Peeled water content 97%, diameter 28c
m, 1 m white lauan, water content 86%, diameter 30
cm, 1 m long white lauan, water content 68%, diameter 2
4cm, 1m long red lauan and water content is 58 ~
88%, 10 cm diameter, 1 m long red lauan peeling core 7
A diameter of 45.5c was obtained in the same manner as in Example 1 except that a book was used.
A laminated log for plywood having a length of m and a length of 1 m was obtained. However, the adhesive strength was low, and the adhesive layer was brittle, so that the pieces were separated during cutting in the rotary race as in Comparative Example 2.

[0022]

[Effect] In the present invention, 80 is used for softening and fixing wood.
Since steam of -100 ° C is used, wood can be easily processed at extremely low cost. Moreover, since the diameter of the obtained laminated log becomes large, continuous veneer can be manufactured from the rotary race, and since the change in water content of the veneer is small, the drying efficiency is good and the plywood production greatly saves labor and energy. can do. In addition, since core defoliation and thinning materials can be used, this also leads to resource saving.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a laminated log for plywood of the present invention.

FIG. 2 is an explanatory view showing a method of manufacturing laminated raw wood for plywood.

[Explanation of symbols]

 1 Integrated raw wood 2 Small diameter wood 3 Compressor 31 Press machine

Claims (1)

[Claims] 1. An isocyanate group content of 1.0 to 2 on the surface of a plurality of small-diameter trees softened by steam at 80 to 100 ° C.
After applying 5.0% by weight of water-curable isocyanate adhesive to the compression processor, the compression ratio of the small diameter tree (total cross-sectional area of the small diameter tree after compression / small diameter tree before compression) It is pressed so that the total cross-sectional area x 100) is 60 to 70%, the small-diameter trees are bonded and integrated together, the water content in the small-diameter trees is made uniform, and the adhesive remains in the pressed state. A method for producing laminated lumber for plywood, which is characterized by fixing the deformation with steam at 80 to 100 ° C. for 10 minutes or more after sufficiently curing.