JPH11156815A - Manufacture of wood material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hardly expect any dimensional warpage even in the case a low- density wood material which is unused is applied for use and therefore, make even this unused low-density wood material available for actual use applications. SOLUTION: This method is to heat plural pieces of wood stick to which an adhesive is applied in such a state that these are laminated to each other, and then allow the adhesive to be set to make the pieces as a whole monolithic. In this case, when getting the adhesive by heat, compressing the sticks makes them densely bound together in one piece compared to the raw material wood. After this process, a high temperature and high pressure steam is supplied to moderate a compression/restoration stress and thereby, the compression/ restoration rate is set at 5% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wood-based material by bonding and integrating wood sticks to each other, and more particularly to a method for manufacturing a wood-based material having a small dimensional change due to moisture or the like.

[0002]

2. Description of the Related Art In recent years, as a building material, a timber product (engineered wood product or engineering wood, hereinafter referred to as EW) for so-called timber engineering, which has a small variation in performance and a guaranteed strength performance in recent years. ) Is increasingly used.

[0003] Such EW includes, for example, framed wall construction lumber (MS) for classifying mechanical bending stress.
R), structural glulam, oriented strand
Board (OSB).

[0004] Of these EWs, structural glued laminated timber and OS
B is a wood-based reconstituted material (hereinafter, referred to as reconstituted EW) obtained by dividing wood into elements of a fixed size, collecting a large number of the elements, and integrating them with an adhesive or the like. By dividing wood, which is a raw material, into elements, it is possible to disperse or remove performance defects such as knots inherent in wood. be able to. In addition, in these reconstructed EWs, since the raw wood is subdivided, it can be manufactured from lumber, which cannot be used as a lumber as it is, or thinned lumber, etc. from the viewpoint of effective use of resources. Is also useful.

[0005]

By the way, as the raw material wood of the reconstructed EW as described above, a high-density, high-strength, high-quality material has conventionally been mostly used in view of the required strength performance. However, these high-quality materials are becoming difficult to obtain due to the recent trend of global environmental protection.

[0006] The plate-shaped product described in Japanese Patent No. 2527761 is intended to satisfy the strength performance by using low-quality wood as a raw material and increasing the compression density. Useful in solving.

[0007] However, according to the research by the present inventors, these products have a stress that tends to restore the compressive force at the time of manufacturing, and when such products are exposed to rainwater at a building site or the like. However, it has been found that products often swell. Particularly, from the viewpoint of effective use of resources, when a product is obtained by using an unused low-density material and performing high compression, the product expands greatly in accordance with the compression ratio. As a result, the dimensions of the material are out of order, and it is very difficult to use it as a prefabricated material, especially when it is difficult to make corrections on site.

[0008] Even after construction, especially in a high-temperature and high-humidity environment such as Japan, the same swelling occurs due to the dew condensation inside the walls and floors, and the wall surfaces and floor surfaces are distorted or misaligned. Or the flaw of it.

[0009] The present invention has been made in view of such circumstances, and it is unlikely that the use of an unused low-density material will cause dimensional irregularities. It is an object of the present invention to provide a method for producing a wood-based material.

[0010]

Means for Solving the Problems In order to achieve the above object, a method for producing a wood-based material according to the present invention is characterized in that a plurality of wood sticks to which an adhesive has been applied are stacked and heated to heat the adhesive. This is a method of manufacturing a wood-based material that cures and integrates the entirety.When the adhesive is cured by heating, the sticks are compressed to a higher density than the raw wood, and the whole is integrated. The present invention is characterized in that the compression restoring stress is relaxed by supplying the steam of (1), and the compression restoring ratio is set to 5% or less (claim 1).

Here, in the present invention, the raw wood is 1
Compression of 0% or more is desirable for obtaining a high-strength product (claim 2).

In the present invention, it is preferable that the width of the wood stick is 2 to 50 mm, the thickness is 0.1 to 10 mm, and the length is 50 to 3000 mm.

Further, in a more specific manufacturing method of the present invention, in a state where a plurality of wood sticks coated with an adhesive are stacked, the adhesive is hardened by heating, and the whole is integrated to form a wood-based material. A manufacturing method, comprising a width of 10 to 3
After applying an isocyanate-based adhesive to a veneer stick having a thickness of 0 mm, a thickness of 1 to 4 mm, and a length of 200 to 2000 mm, a plurality of the veneer sticks are placed in a press device, and steam is directly injected to press the stick while heating the stick. By doing
The adhesive in a pressurized state of each stick integrated whole is thermally cured, and moldings all dry density is compressed densified up 0.5~0.8g / cm ^3, then, in a closed vessel While maintaining the shape of the above-mentioned molded product with the arranged mold, high-temperature and high-pressure steam is introduced into the closed container to perform a steam treatment on the molded product, thereby alleviating the compressive restoring stress and increasing the compression-recovery rate by 5%.
% Or less is adopted (claim 4).

In the present invention, the compression / decompression rate is defined as follows. Compression recovery ratio (%) = {(dimension after drying−dimension before immersion treatment) / dimension before immersion treatment} × 100 However, in this formula, the immersion treatment is an immersion treatment in water at a water temperature of 40 ° C. or lower ( For example, European standard EN317
(Immersed in water at 20 ° C. for 24 hours). The term “drying” refers to drying after the immersion treatment to a moisture content before the immersion treatment, and the term “dimensions” refers to the dimension of the evaluation sample in the compression molding direction of the product.

In the present invention, the compression ratio is defined as follows. Compressibility (%) = {(density of product−density of raw wood) / density of product} × 100 In the present invention, the stick refers to a bar-shaped piece having a substantially constant width and thickness in the length direction.

In the third aspect of the present invention, the size of the wood stick as the element is 2 to 50 mm in width, 0.1 to 10 mm in thickness, and 50 to 3000 mm in length. But it can be used. However, it is preferable to use a wood stick in the above range for the following reasons.

First, it is difficult to make a stick having a width smaller than the above range. Conversely, if the width is wide, the seam of the stick becomes wider in a product integrated and bonded. The effect of dispersing the defects in the raw wood to make the strength uniform is weakened. If the thickness is less than the above range, it is difficult to make a stick.If the thickness is too large, large voids are likely to occur at the seam of the stick inside the bonded and integrated product. As a result, the effect of making the strength uniform is weakened. If the length is shorter than the above range, the required strength performance may not be obtained. On the other hand, if the length is longer, the stick is inefficient because the original raw wood needs to be longer.

Among the above ranges, the width is 5 to 30 mm,
A thickness of 0.5 to 5 mm and a length of 200 to 2000 mm are preferable in terms of product performance, ease of stick production, and ease of handling. Among them, width 10
30mm, thickness 1-4mm, length 400-1500mm
Is more preferable. In particular, as for the relationship between the thickness and the length, it is preferable that the ratio is 1:20 or more from the viewpoint of product performance. The relationship between the thickness and the width is not particularly limited, and a square cross-sectional shape (thickness: width = 1: 1) may be used.

In the present invention, a known method such as cutting, cutting, splitting, or the like can be used as a method for producing the stick. Specifically, for example, a method in which a veneer veneer is prepared from a raw material log with a veneer racer, and the veneer veneer is formed into a stick shape by cutting, cutting, splitting or the like from the veneer veneer can be preferably used. Also, a stick may be made by directly splitting from a lumber back plate, a small diameter tree, a veneer peeling core, or the like. However, the method using a flaker is not very preferable for the following reasons.

That is, in the method using a flaker, it is possible to produce a thin stick-like product (generally called a wafer). In this case, however, the width of the obtained stick-like product is reduced due to the production method. Becomes considerably wide, which is not preferable for the above-mentioned reason. In addition, it is very difficult to make a thin and not wide stick by a method using a flaker.

Examples of raw wood that can be used in the present invention include cypress, sawara, hiba, kaya, cedar,
Toga, maki, various pine, paulownia, maple, birch, spine, beech, oak, fir,
Domestic lumber, oak, kusu, zelkova, rice cypress, rice hiba, rice cedar,
North American lumber such as Yonemozumi, spruce, Yonematsu, hard pine, soft pine, Yonega, redwood, aspen, etc., Southsea lumber such as Agathis, Terminaria, Rawan, Merunch, Sengong Laut, Jonkon, Chamelere, Karampayan, Amberoi, Melina, Teak , Other, balsa, cedro, mahogany, lignum vita, radiata pine, etc.
Any material can be used. In addition, the form is not limited to ordinary logs and lumber products, but can also be used for lumber backboards, small-diameter trees, thinning materials, building scraps, construction waste materials, and the like.

Among them, high-density tree species, such as rice pine, which are usually used for structural purposes as lumber products, are further compressed by high compression as described in claim 2 to achieve higher strength. Can be expected, and the effect of uniform stabilization of performance can be obtained because the defective portions such as nodes are removed.

Further, low-density, low-physical materials that cannot be used for structural purposes in lumber products made only from raw wood, such as aspen, sengonglaut, chamelere, etc. among the above-mentioned wood species. Even if it is highly compressed as in the invention of claim 2, it becomes a material that can be suitably used for structural applications.

In terms of density, the total dry density is 0.2 to 0.4
It is particularly preferable to apply the low-density fast-growing tree of g / cm ³ to, for example, the invention described in claim 4 from the viewpoint of utilizing woody materials.

Since the strength performance of a product is highly correlated with the density of the product, the density of the product can be selected according to the strength required there based on the application of the product, but in general, 0.3-0.9g in a completely dry state
/ Cm ³ , and more preferably 0.4 to 0.8 g / cm ³ in a completely dry state.
The method of the present invention has an advantage that the required product density can be set freely, unlike ordinary lumber products.

In the present invention, a known method can be applied as a heating and pressing method for bonding and integrating a wood stick. For example, any of a batch method such as a hot plate press and a steam injection press and a continuous press method using heating such as microwave, high frequency dielectric heating, and steam injection can be applied. Among them, in the method by continuous pressing, the length of a molded product can be arbitrarily set as required, and therefore, the method is preferable because of high material efficiency.

In the present invention, various methods can be applied as a method for performing high-temperature and high-pressure steam treatment.
For example, a method in which high-temperature and high-pressure steam is introduced into a container while maintaining the shape of the molded product using a mold installed in a closed container, or a hot plate, microwave, or high-frequency dielectric heating Heating by such methods as evaporating the moisture in the molded product, or sealing around the mold, forming a closed space with the mold itself, installing the molded product in it, A method of performing steam treatment by the above-described method of introducing high-temperature and high-pressure steam or vaporizing moisture by a hot plate, microwave, high-frequency dielectric heating, or the like can be employed.

When the compressive restoring stress is reduced by high-temperature and high-pressure steam processing, the required processing time is determined by the processing temperature as shown in the graph of FIG. For example, when the treatment is performed at 200 ° C., the treatment time may be about 4 minutes (time for maintaining the high-temperature and high-pressure state). When the treatment is performed at 180 ° C., the high-temperature and high-pressure state is preferably maintained for 10 minutes or more.

In the present invention, as the adhesive used for bonding and integrating the wood sticks, known adhesives used in the production of plywood can be applied. That is, for example, phenol-based, resorcinol-based, urea-based, melamine-based, maleic acid-based, isocyanate-based adhesives, co-condensates thereof, or mixtures thereof are used.

(Function) The present invention forms a woody material which satisfies the required strength performance by bonding and integrating a large number of wood sticks in a state where they are compressed to a higher density than the raw wood. By performing high-temperature, high-pressure steam treatment, the compression restoring stress is reduced, the expansion due to moisture is reduced, and the intended purpose is achieved. When relaxing the compression restoring stress, the degree of relaxation of the compression restoring stress is quantified by using the compression restoring rate as a parameter, and the compression restoring stress is surely relaxed.

That is, wood originally has the property of swelling when absorbing water and contracting when dried. Usually, lumbering is performed in a state close to freshly cut raw trees, and dried to produce lumber products. In such a case, warpage due to drying shrinkage,
Deviation such as bending occurs. In the case of conventional construction of houses, such irregularities did not become a major problem, because the modification work was possible at the construction site.

However, in the case of a method using pre-cutting of wood, a house using a frame wall method, and an industrialized house (prefabricated house) which are increasing in recent years, the material requires high dimensional accuracy. Becomes Reconstitution EW uses dried materials as raw materials,
Such drying shrinkage does not occur and is useful.

However, since the high-density reconstructed EW is made by compression-molding the raw wood, if the water is absorbed by the dew water in the wall or the rainwater at the construction site, not only the original expansion of the wood but also the expansion. In addition, expansion due to compression recovery is added, causing considerable size deviation in the wet state (the original water absorption expansion of wood is about 3 to 5%, but the compression recovery expansion is about 10% even if it is small depending on the compression ratio. , 20 for a big one
% Or more are observed). In the case of ordinary house construction, the expansion of about 5% is about the same as the original water absorption expansion of wood, so it is a size that can be sufficiently eliminated by the construction method, but if it is larger than that, the construction method needs to be changed And

Further, since the compression-recovery expansion is irreversible unlike the original water-absorbing expansion-drying shrinkage of wood, even if the water-absorbed product is dried, the irregularity of the dimensions remains. If such a disorder is large, the product cannot be used,
In the case of an industrialized house, it may be necessary to change the production line to correct the disorder. In addition, in a house after construction, if it exceeds the level that can be resolved by the construction method, steps will occur on the floor or wall, nails, bolts, brackets, etc. for fixing will be inset, or reverse. It will be lost.

In the manufacturing method of the present invention, after the wood stick is bonded and integrated in the compressed state and compressed to a higher density than the raw wood, the compression recovery rate defined as described above is 5% or less. In addition, since the method includes a step of relaxing the compression / restoration rate by high-temperature and high-pressure steam processing, the above-described problems unique to the conventional high-density reconstruction EW do not occur.

Here, the method of measuring the coefficient of water absorption swelling according to a normal specification or the like is to expand by water spraying or immersion, and to measure the dimensions in a wet state. In such a method, there is no distinction between the natural water-absorbing swelling-drying shrinkage and the compression-restoring expansion of wood.
Here, in the present invention, as described above, take the ratio of the dimensions before immersion and the dimensions after drying, and define it as the compression recovery ratio,
Since this is used as a reference, it is possible to clearly classify the compression / decompression / expansion which is a problem in the high-density reconstruction EW.

[0037]

EXAMPLES Examples in which a reconstructed EW is actually manufactured by applying the present invention will be described below together with comparative examples.

Example 1 Yonematsu (total dry density 0.5 g / c)
A veneer veneer was prepared from a log of m ³ ) with a veneer racer, and the veneer was split by passing between a pair of rotary blades to prepare a stick having a width of 10 mm, a thickness of 4 mm, and a length of 1000 mm. .

After the stick was dried to a moisture content of 7%, 5 parts by weight of an adhesive (polymeric MDI) was spray applied to 100 parts by weight of the total dry weight of the stick. 7.0 kg of this stick is heated and pressed in a hot plate press at 120 ° C. for 10 minutes, and the width is 240 m.
m, a thickness of 45 mm, and a length of 1000 mm. Thereafter, the plate was steamed in an autoclave at 180 ° C. for 10 minutes to reduce the compression restoring stress.

The density of the obtained molded product was 0.6 in terms of total dry weight.
g / cm ³ (compression rate 16.7%) and a bending stress of 8
00 kgf / cm ² , flexural modulus is 110000 kgf
/ Cm ² (measured at a water content of 10%). Also, 20
After immersion in water at 24 ° C. for 24 hours, it was dried in an oven at 60 ° C. for 3 hours, and the compression recovery rate was measured.

Example 2 A stick was prepared from a log of Sengong Laut (total dry density: 0.25 g / cm ³ ) in the same manner and in the same size as in Example 1, and the water content was 4%.
After drying to the same extent, the same type of adhesive as in Example 1 was spray applied under the same weight parts. This stick was held for 10 minutes while injecting steam at 180 ° C. by a steam-injection continuous press to form a sheet, and then cut to form a plate having the same dimensions as in Example 1. Thereafter, the plate was subjected to a relaxation treatment of the compression restoring stress in the same manner as in Example 1.

The density of the obtained molded article was 0.5
5 g / cm ³ (compression rate 54.5%) and bending stress 48
0 kgf / cm ² , flexural modulus is 79000 kgf / c
m ² (measured at a water content of 10%). After immersion in 20 ° C. water for 24 hours, drying in a 60 ° C. oven for 3 hours and measurement of the compression recovery rate revealed 4%.

(Example 3) 6.0 kg of the stick of the Sengong Laut prepared in Example 2 to which the adhesive was applied was formed by a hot plate press under the same method and conditions as in Example 1, and then the Example 1 was used. The compression stress was relaxed in the same manner as described above.

The density of the obtained molded article was 0.5 in terms of total dry weight.
5 g / cm ³ (compression rate 54.5%) and bending stress 48
0 kgf / cm ² , flexural modulus is 79000 kgf / c
m ² (measured at a water content of 10%). After immersion in 20 ° C. water for 24 hours, drying in a 60 ° C. oven for 3 hours and measurement of the compression recovery rate revealed 4%.

Example 4 Chamelere (total dry density 0.32)
g / cm ³ ), a stick was prepared according to the same method and dimensions as in Example 1 and dried to a water content of 7%, and then the same type of adhesive as in Example 1 was applied by the same method. This stick was molded under the same conditions by the same steam injection continuous press as in Example 2 and cut to form a plate having the same dimensions as in Example 1. After that, compression stress was relaxed in the same manner as in Example 1.

The density of the obtained molded article was 0.5
5 g / cm ³ (compression ratio 41.8%) and bending stress 53
0 kgf / cm ² , flexural modulus 83,000 kgf / c
m ² (measured at a water content of 10%). After immersion in water at 20 ° C. for 24 hours, the film was dried in an oven at 60 ° C. for 3 hours, and the compression recovery rate was 3%.

(Comparative Example 1) A plate having the same dimensions was formed in the same manner as in Example 1 except that the compressive stress relaxation treatment was not performed. The density of the obtained molded product is 0.6 g / c on a dry basis.
m ³ (compression rate 16.7%), bending stress 900 kgf
/ Cm ² , flexural modulus is 130,000 kgf / cm
² (measured at a water content of 10%). After immersion in water at 20 ° C. for 24 hours, the film was dried in an oven at 60 ° C. for 3 hours, and the compression recovery rate was measured to be 10%.

(Comparative Example 2) A plate having the same dimensions was formed in the same manner as in Example 2 except that the compressive stress relaxation treatment was not performed. The density of the obtained molded article was 0.55 g /
cm ³ (compression rate 54.5%), bending stress 500 kg
f / cm ² , flexural modulus is 80000 kgf / cm
² (measured at a water content of 10%). After immersion in 20 ° C. water for 24 hours, drying in a 60 ° C. oven for 3 hours, and measurement of the compression recovery ratio, it was 25%.

Comparative Example 3 A plate having the same dimensions was formed in the same manner as in Example 3 except that the compression stress relaxation treatment was not performed. The density of the obtained molded product is 0.55 g / c in terms of total dryness.
m ³ (compression rate 54.5%), bending stress 500 kgf
/ Cm ² , and the flexural modulus was 80000 kgf / cm ² (measured at a water content of 10%). In addition, 24 ° C in 20 ° C water
After immersion for a period of time, the film was dried in a 60 ° C. oven for 3 hours, and the compression recovery rate was measured. As a result, it was 25%.

Comparative Example 4 A plate having the same dimensions was formed in the same manner as in Example 4 except that the compression stress relaxation treatment was not performed. The density of the obtained molded product is 0.55 g / c in terms of total dryness.
m ³ (compression rate 41.8%), bending stress 540kgf
/ Cm ² , and the flexural modulus was 83000 kgf / cm ² (measured at a water content of 10%). In addition, 24 ° C in 20 ° C water
After immersion for a period of time, the film was dried in a 60 ° C. oven for 3 hours, and the compression recovery rate was measured to be 18%.

[0051]

According to the present invention, a plurality of wood sticks are laminated in a state where an adhesive is applied to the wood sticks, and are compressed at the time of heating to have a higher density than the raw wood, and the whole is bonded and integrated. High temperature and high pressure steam treatment alleviates the compressive restoring stress and reduces the compressive restoring ratio to 5% or less. Therefore, even if low-density materials, which have not been used in the past, are used as raw wood, contact with rainwater and generation of dew water will occur. Even if moisture is absorbed by the above-described method, the dimensional change is greatly reduced as compared with the conventional high-density reconstruction EW of this type. As a result, the EW used for an industrialized house or the like does not become unusable as a defective product, and there is no need to change the line to correct the error. In addition, even in the house after construction, sinking of steps and metal fittings,
No dropout occurs.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a processing temperature and a processing time in order to effectively reduce compression restoring stress by high-temperature and high-pressure steam processing in the present invention.

Claims (4)

[Claims] 1. A method for producing a wood-based material in which a plurality of wood sticks to which an adhesive has been applied are stacked and heated to harden the adhesive and integrate the whole.
When the adhesive is cured by heating, after compressing the stick to make it denser than the raw wood and integrating the whole, the high-temperature and high-pressure steam is supplied to reduce the compressive restoring stress and increase the compressive restoring rate. A method for producing a wood-based material, wherein the content is 5% or less. 2. The method for producing a wood-based material according to claim 1, wherein the raw wood is compressed by 10% or more by the compression. 3. The method according to claim 1, wherein the stick has a width of 2 to 50 mm, a thickness of 0.1 to 10 mm, and a length of 50 to 3000 mm. 4. A method for producing a wood-based material, in which a plurality of wood sticks coated with an adhesive are heated and the adhesive is cured by heating to integrate the whole.
Width 10-30mm, thickness 1-4mm, length 200-20
After applying an isocyanate-based adhesive to a 00 mm veneer stick, a plurality of the isocyanate-based adhesives are arranged in a press device, and the pressure is applied while directly heating the sticks by directly injecting steam. Is heat cured to integrate the whole, and the total dry density is 0.5 to 0.8 g / c.
until m ³ and compression densified molded article, then, while the molded article arranged mold in a closed container to retain its shape, the molded product by introducing high-temperature high-pressure steam in a sealed container A method for producing a wood-based material, characterized in that a compressive restoring stress is reduced by steaming the material, and the compressive restoring ratio is set to 5% or less.