JP2023170209A - Wood laminate, and manufacturing method therefor - Google Patents

Abstract

To provide a wood laminate exhibiting excellent properties in safety and design, that prevents fracture from being generated during use, that exhibits excellent workability when performing a three-dimensional molding process, and to provide a manufacturing method therefor.SOLUTION: According to a wood laminate comprising a single sheet layer (A) made of wood, and an adhesive layer (B), the wood laminate is characterized in that fracture elongation in a fiber direction of the single sheet layer (A) is 1.5 to 5.0%.SELECTED DRAWING: None

Description

The present invention relates to a wood laminate and a method for manufacturing the same. In particular, the present invention relates to a wood laminate that has excellent workability when subjected to three-dimensional molding, is resistant to breakage during use, and has excellent safety and design, and a method for producing the same.

Wood has a unique appearance such as wood grain, and is a material with excellent design properties that gives an impression of "warm", "soft", and "luxury", for example. Among these, plywood, which is made by laminating wood veneers, is widely used as small to large wood components such as small items, furniture, and building materials.

One of the uses of plywood is as plywood for three-dimensional molding. This process produces plywood with a curved surface by bending and forming the plywood using heat and pressure, and is widely used for furniture such as tables and chairs, which particularly require a high level of design.
On the other hand, compared to metal materials such as iron, wood is a material that easily breaks after yielding in bending and is difficult to deform flexibly. As a result, yields decrease due to cracks during the plywood forming process, and cracks and cracks occur mainly due to deformation of the plywood due to the application of loads such as body weight during use, resulting in safety and design issues. There were issues such as a decline in performance.

Up to now, attempts have been made to solve the above problems by improving the deformability of plywood and the like against loads. For example, in Patent Document 1, an attempt is made to improve the deformability of plywood by combining a veneer and a highly flexible adhesive, and in Patent Document 2, a specific patterned cut is formed in wood. Attempts have been made to impart deformability to wood by doing so.

Japanese Patent Application Publication No. 2010-36359 Japanese Patent Application Publication No. 2011-93249

However, after various studies by the present inventors, although the method of Patent Document 1 improves the deformability of plywood, it does not solve the problem of breakage after applying a specific load, and it does not solve the problem of three-dimensional formability. It was found that this method was insufficient in terms of safety during use and design.
In addition, the method of Patent Document 2 has problems from a design perspective because visible notches are formed in the wood, and the thickness of the veneer cannot be made thinner, and in principle there is a possibility that the veneer will break after a specific load is applied. There are various problems that remain unresolved.

Therefore, it is against this background that the present invention aims to provide a wood laminate that has excellent workability when subjected to three-dimensional molding, is resistant to breakage during use, and has excellent safety and design. shall be.

However, as a result of intensive studies to solve the above problems, the present inventors surprisingly discovered that the above problems could be solved by using a specific wooden veneer layer, and completed the present invention.

That is, the present invention has the following aspects.
[1]
A wood laminate having a wooden veneer (A) layer and an adhesive (B) layer, wherein the elongation at break in the fiber direction of the wooden veneer (A) is 1.5 to 5.0%. A wood laminate characterized by:
[2]
The wood laminate according to [1], wherein the wooden veneer (A) layer has a thickness of 0.3 to 3.0 mm.
[3]
The wood laminate according to [1] or [2], wherein the wooden veneer (A) does not have a slit of 0.2 mm or more in the thickness direction.
[4]
The wood laminate according to any one of [1] to [3], wherein the wooden veneer (A) is a cellulose-based fibrous structure.
[5]
The wood laminate according to any one of [1] to [4], which is for three-dimensional molding.
[6]
A method for producing a wood laminate according to any one of [1] to [5], comprising a step of applying pressure to the wooden veneer (A) layer and the adhesive (B) layer and bonding them together. Method for manufacturing wood laminates.
[7]
The method for producing a wood laminate according to [6], wherein the adhesive (B) layer is a sheet-like adhesive (B) layer.
[8]
A molded article obtained from the wood laminate according to any one of [1] to [5].

The present invention can provide a wood laminate that has excellent workability when three-dimensionally molded, is difficult to break during use, and has excellent safety and design.

FIG. 2 is an external view (photograph) of the test sample of Example 1 of the present invention after a horizontal shear test. It is an external view (photograph) of the test sample of Example 2 of the present invention after a horizontal shear test. FIG. 2 is an external view (photograph) of a test sample of Comparative Example 1 of the present invention after a horizontal shear test. It is an external view (photograph) of the test sample of Comparative Example 2 of the present invention after a horizontal shear test. It is a figure showing the shape of the test sample used in the breaking elongation test of the example of this invention, and a comparative example.

Hereinafter, the present invention will be explained in detail, but these are examples of desirable embodiments. In this specification, "~" represents a range of numbers including the numbers written before and after it.

The wood laminate of the present invention is a wood laminate having a wooden veneer (A) layer and an adhesive (B) layer, and the wood veneer (A) has an elongation at break in the fiber direction of 1.5. 5.0%.
First, the wooden veneer (A) layer and the adhesive (B) layer will be explained.

<Wooden veneer (A) layer>
The wooden veneer (A) layer is a layer composed of wooden veneers (A), and the wooden veneer (A) is a cellulose-based fibrous structure whose main component is cellulose and has a fibrous structure in a specific direction. Consists of the body.

Examples of cellulose-based fibrous structures include wood-based or non-wood-based cellulose-based fibrous structures.
Examples of wood-based cellulose-based fibrous structures include conifer-based cellulose-based fibrous structures such as cedar, cypress, and Sitka spruce, and hardwood-based cellulose-based fibrous structures such as beech and walnut.
Examples of non-wood cellulose-based fibrous structures include herbaceous cellulose-based fibrous structures such as bamboo, kenaf, bayberry, and banana.

Among these, wood-based cellulose-based fibrous structures are preferred from the viewpoint of easily controlling the elongation at break (%) in the fiber direction within the specific range specified in the present invention, and conifer-based cellulose-based fibrous structures are preferred. , broad-leaved cellulose-based fibrous structures are more preferred, and cedar, cypress, Sitka spruce, beech, and walnut are particularly preferred.

In addition, the above-mentioned "main component" means that the content ratio of cellulose to the entire cellulose-based fibrous structure constituting the wooden veneer (A) is 45% by weight or more, preferably 50% by weight or more. ~90% by weight, particularly preferably 55-70% by weight.
Further, the content of cellulose can be determined by a known measuring method, for example, by the measuring method described in "Journal of Mokuzai Gakkai, 1983, No. 29, p. 702."

The elongation at break (%) in the fiber direction of the wooden veneer (A) must be within a specific range of 1.5 to 5.0%, preferably 1.6 to 4.8%, especially Preferably it is 1.7 to 4.7%. If it is below these ranges, there is a tendency for large breaks to occur when a specific load is applied to the wood laminate. On the other hand, if it exceeds these ranges, the strength of the wood laminate tends to decrease.

Methods for controlling the elongation at break (%) in the fiber direction of the wooden veneer (A) within the range of 1.5 to 5.0% include, for example, optimizing the processing curvature during pre-deformation processing and controlling the upper limit of the amount of deformation. Although setting may be mentioned, it is preferable to set a machining curvature for pre-deformation that corresponds to an amount of deformation that does not exceed the breaking strain of the workpiece.

Note that the elongation at break (%) of the wooden veneer (A) in the vertical direction (direction orthogonal to the fiber direction) is not particularly limited, but is, for example, 1.0 to 6.0%.

The elongation at break (%) in the fiber direction and the elongation at break (%) in the vertical direction of the wooden veneer (A) are measured according to the tensile test of JIS K7164, for example, by the method described in the Examples below. It is measured by

The above-mentioned "fiber direction" refers to the running direction of annual rings, vessels, and wood fibers along the growth direction of the tree trunk, and means the direction in which the tree grows.

The thickness of the wooden veneer (A) layer is variously selected depending on the type of wood laminate, but is usually 0.1 to 3.0 mm, preferably 0.3 to 3.0 mm, and 0.4 to 2.0 mm. 5 mm is more preferable, and 0.5 to 1.5 mm is particularly preferable. If it is below these ranges, the strength of the wood laminate tends to decrease. On the other hand, if it exceeds these ranges, the formability of the wood laminate tends to deteriorate.

It is preferable that the wooden veneer (A) of the present invention does not have slits of a certain depth or more on the surface. Here, the slit means a groove formed by cutting the surface of a wooden veneer. Specifically, a slit has a specific depth extending in the thickness direction of the wooden veneer (A), a specific length extending in the length direction of the wooden veneer (A), and a slit that extends in the thickness direction of the wooden veneer (A). It means a concave shape having a specific width extending in the width direction, but it also includes a through hole. Furthermore, the shape of the slit in plan view is not limited to a rectangular shape, and may be, for example, circular, elliptical, triangular, polygonal, or the like.
The wooden veneer (A) of the present invention preferably does not have slits with a depth of 0.2 mm or more, particularly preferably does not have slits with a depth of 0.1 mm or more, and has a depth of 0.05 mm or more. It is more preferable to have no slits, and more preferably not to have slits with a depth of 0.02 mm or more.
Further, the length of the slit is preferably not more than 2 cm, particularly preferably not more than 1 cm, even more preferably not more than 0.5 cm, and not more than 0.2 cm. It is more preferable. Further, the width of the slit is preferably not more than 2 mm, particularly preferably not more than 1 mm, even more preferably not more than 0.5 mm, and not more than 0.2 mm. is more preferable.
Exceeding these ranges is unfavorable from the viewpoint of the design and strength of the veneer. Note that the lower limit is not particularly limited, but it is most preferable to have no slits from the viewpoint of improving the design and the strength of the wood laminate. The slits herein do not include slits that do not affect the elongation at break of the present invention, such as cuts used for interlocking wood laminates.

As the wooden veneer (A) of the present invention, as long as the elongation at break (%) in the fiber direction is within the above range, a wooden veneer manufactured by a known method may be used as it is, and furthermore, a wooden veneer manufactured by a known method may be used as is. A processed one may also be used.
Examples of the wooden veneer manufactured by a known method include a veneer manufactured from a specific raw wood or a flitch obtained by sawing the raw wood to a predetermined size using a cutting device. More specifically, examples include rotary veneer obtained by peeling raw wood with Katsura peeling, and sliced veneer obtained by cutting raw wood into rectangular lumber with a slicer.
In addition, examples of processing methods for wooden veneers include impregnation processing in which the wooden veneer is impregnated with a resin component such as polyethylene glycol, pattern processing in which a pattern is created in the wooden veneer by cutting or compression, and the like. Among these methods for processing wooden veneers, from the viewpoint of reducing the impact on the environment during use, it is preferable not to perform impregnation processing to impregnate resin or the like. That is, it is preferable to use a veneer manufactured from raw wood or a flitch obtained by sawing the raw wood into a predetermined size using a cutting device as a wooden veneer as it is.

<Adhesive (B) layer>
The adhesive (B) layer is a layer composed of adhesive (B), and the adhesive (B) has good adhesive properties to the wooden veneer (A). It is not particularly limited as long as it has a pressure-sensitive adhesive, an adhesive, and a mixture thereof.

Examples of the adhesive include acrylic adhesive, polyurethane adhesive, polyester adhesive, rubber adhesive, and silicone adhesive.
Examples of adhesives include thermoplastic adhesives (hot melt adhesives) such as polyolefin adhesives, ethylene vinyl acetate adhesives, polyamide adhesives, polyurethane adhesives, and polyester adhesives, and acrylic urethane adhesives. Examples include thermosetting adhesives such as adhesives, modified silicone adhesives, cyanoacrylate adhesives, urea adhesives, phenolic adhesives, and epoxy adhesives. Among these, pressure-sensitive adhesives and thermoplastic adhesives are preferred from the viewpoint of imparting flexibility and reprocessability to the wood laminate itself.

Among the adhesives, acrylic adhesives, polyurethane adhesives, and polyester adhesives are preferred from the viewpoint of further improving the adhesiveness with the wooden veneer (A). Further, the glass transition temperature (Tg) of the adhesive is preferably 0°C or lower, more preferably -15°C or lower, particularly preferably -30°C or lower. Within these ranges, the adhesion to the wooden veneer (A) tends to be further improved.

Note that the above glass transition temperature is calculated by, for example, the Fox equation. For example, the glass transition temperature of an acrylic adhesive is calculated as follows.

That is, the glass transition temperature (Tg) is a value calculated by applying the glass transition temperature and weight fraction when each monomer constituting the adhesive is a homopolymer to the above Fox equation. The glass transition temperature of the homopolymer of the monomers constituting the adhesive is usually measured using a differential scanning calorimeter (DSC), and is based on JIS K7121-1987 and JIS K 6240. It can be measured using the following method.

Among the thermoplastic adhesives, ethylene vinyl acetate adhesives, polyurethane adhesives, and polyester adhesives are preferable from the viewpoint of further improving the adhesion to the wooden veneer (A). is particularly preferred.

The flow initiation temperature of the thermoplastic adhesive is preferably 80 to 140°C, more preferably 90 to 130°C, particularly preferably 100 to 120°C. Within these ranges, there is a tendency for the wooden veneer (A) to undergo little deterioration during adhesion and to obtain a wood laminate with excellent heat resistance.
Note that the above-mentioned flow start temperature is measured by a Koka type flow tester (load: 30 kgf/cm ² ).

The fluidity (MFR) of the thermoplastic adhesive is preferably 0.1 to 100 g/10 min, more preferably 0.1 to 95 g/10 min, particularly preferably 0.2 to 80 g/10 min. If it exceeds or falls below these ranges, there is a tendency for adhesion to the wooden veneer (A) to be insufficient during bonding such as press molding.
In addition, the said fluidity|liquidity is measured by 125 degreeC MFR (load 0.325 kg) based on JISK7210.

The adhesive (B) layer may contain additives other than the adhesive (B) as long as the adhesion to the wooden veneer (A) layer is not impaired. Examples of additives include non-dielectric fillers such as silica, alumina, and calcium carbonate; dielectric fillers such as zinc oxide, titanium oxide, barium titanate, lead titanate, potassium niobate, and aluminum silicate; glass fibers and polyester fibers. Fibrous bodies for shape retention; antioxidants, hydrolysis inhibitors, light stabilizers, flame retardants, plasticizers; and the like. These may be used alone or in combination of two or more. In addition, from the viewpoint of easily producing the wood laminate of the present invention, it is preferable that the adhesive (B) layer does not contain these additives.

The adhesive (B) constituting the adhesive (B) layer may be in any form such as pellets, powder, or sheet, but is preferably in sheet form from the viewpoint of workability.
The thickness of the adhesive (B) layer is variously selected depending on the type and shape of the wood laminate, but is usually 10 to 400 μm, preferably 20 to 300 μm, and particularly preferably 30 to 200 μm. If it is below these ranges, the adhesion between the adhesive (B) layer and the wooden veneer (A) layer tends to decrease. On the other hand, if it exceeds these ranges, the strength of the wood laminate tends to decrease.

<Other layers>
The wood laminate of the present invention may contain other layers in addition to the wooden veneer (A) layer and the adhesive (B) layer, as long as the workability and design thereof are not impaired. Other layers include, for example, cellulose-based fibrous structures whose elongation at break (%) in the fiber direction is outside the range of 1.5 to 5.0, that is, elongation at break (%) in the fiber direction is less than 1.5. Examples include a cellulose-based fibrous structure having a fiber-direction elongation at break (%) of more than 5.0.
Other layers include, for example, resins such as polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyvinyl chloride, nylon 610 (PA610), nylon 6T (PA6T), polyphenylene sulfide, elastomer, polystyrene; iron; , metals such as stainless steel, copper, and aluminum; fiber-reinforced plastics such as CFRP, and the like may be used alone or in combination of two or more thereof. Among these, cellulose-based fibrous structures having an elongation at break (%) in the fiber direction outside the range of 1.5 to 5.0 are preferred from the viewpoint of easily providing the wood laminate of the present invention. From the viewpoint of further exerting the effects of the wood laminate of the invention, it is preferable that no other layers are included.

The thickness of the other layers is variously selected depending on the type of wood laminate of the present invention, but is usually 0.1 to 3.0 mm, preferably 0.3 to 2.5 mm, and 0.5 to 1.5 mm. is particularly preferred.

<Method for manufacturing wood laminate>
The wood laminate of the present invention is produced by a process of manufacturing a wooden veneer (A) with an elongation at break in the fiber direction of 0.5 to 1.5%, and a process of manufacturing a wooden veneer (A) and an adhesive (B). The laminate is manufactured by using the process of manufacturing a laminate using the laminate.
For example, in the case of a wood laminate that includes at least a first wooden veneer (A) layer, an adhesive (B) layer, and a second wooden veneer (A) layer, the first wooden veneer ( A) and the second wooden veneer (A) are made to face each other in the veneer thickness direction, and the adhesive (B) is interposed between them, so that the first wooden veneer (A) and the second wooden veneer (A) It is manufactured by gluing together wooden veneer (A).
It also includes at least a wooden veneer (A) layer, an adhesive (B) layer, and a wooden veneer (C) layer whose elongation at break in the fiber direction (%) is outside the range of 1.5 to 5.0. In the case of a wood laminate, a wooden veneer (A) and a wooden veneer (C) are placed opposite each other in the thickness direction of the veneer, and an adhesive (B) is interposed between them. It is manufactured by bonding A) and a wooden veneer (C).

The method for producing the wood laminate of the present invention preferably includes a step of applying pressure to the wooden veneer (A) layer and the adhesive (B) layer to bond them together, from the viewpoint of excellent moldability. The pressure in the step of applying pressure and bonding is usually 0.01 to 10 MPa, preferably 0.1 to 5 MPa, and particularly preferably 0.2 to 2 MPa. If it exceeds or falls below these ranges, there is a tendency that the desired shape of the wood laminate cannot be sufficiently secured.

Furthermore, the method for producing the wood laminate of the present invention may include a step of bonding while heating, depending on the type of adhesive (B) and the shape of the intended wood laminate. The heating temperature in this step is preferably 60 to 150°C, more preferably 80 to 140°C, and particularly preferably 90 to 130°C. If it is below these ranges, there is a tendency that the adhesion of the adhesive (B) to the wooden veneer (A) layer cannot be sufficiently ensured. On the other hand, if it exceeds this range, the design of the wood laminate tends to be impaired due to thermal deterioration of the wooden veneer (A).
In addition, as a heating method, for example, a method of heating by heat transfer from press equipment, a method of heating with hot air, a method of heating with electromagnetic waves, etc., which are generally known methods for heating when manufacturing plywood, can be used. .

In the method for producing a wood laminate of the present invention, the method of arranging the adhesive (B) layer between the wooden veneer (A) layers (and other layers) includes, for example, ) is applied to the wooden veneer (A) layer (and other layers) and then laminated; Examples include a method in which a sheet-like adhesive (B) is placed between the wooden veneer (A) layers (and other layers), and the like. Among these, from the viewpoint of manufacturing the wood laminate of the present invention more easily, there is a method in which a sheet-like adhesive (B) is placed between the wooden veneer (A) layers (and other layers). is preferred.

A plurality of wooden veneers (A) included in the wood laminate of the present invention may be laminated with the fiber directions of the wooden veneers (A) arranged in parallel in some or all of them (parallel lamination). ). For example, in a wood laminate that includes at least a first wooden veneer (A) layer, an adhesive (B) layer, and a second wooden veneer (A) layer, the first wooden veneer (A) The second wooden veneer (A) and the second wooden veneer (A) may be stacked with their fiber directions aligned.
In addition, the plurality of wooden veneers (A) included in the wood laminate may be laminated with the fiber directions of the wooden veneers (A) arranged orthogonally to each other in some or all of them (orthogonal lamination). . For example, in a wood laminate that includes at least a first wooden veneer (A) layer, an adhesive (B) layer, and a second wooden veneer (A) layer, the first wooden veneer (A) The first wooden veneer (A) and the second wooden veneer (A) may be stacked with their fiber directions perpendicular to each other. Among these, from the viewpoint of suppressing breakage that occurs when a specific load is applied to the wood laminate, it is preferable to arrange the fiber directions of the wooden veneers (A) in parallel to each other.
A plurality of wooden veneers (A) included in the wood laminate of the present invention may be laminated in part or in whole so that the fiber directions of the wooden veneers (A) are diagonally crossed. (cross-laminated). For example, in a wood laminate that includes at least a first wooden veneer (A) layer, an adhesive (B) layer, and a second wooden veneer (A) layer, the first wooden veneer (A) The first wooden veneer (A) and the second wooden veneer (A) may be stacked so that their fiber directions are diagonally crossed. From the viewpoint of improving the flexibility of the wood laminate of the present invention, the fiber direction of the first wooden veneer (A) and the fiber direction of the second wooden veneer (A) are aligned to one side of the outer shape of the veneer. The direction is inclined at an angle of 20° to 80°, preferably 30° to 60°, more preferably 40° to 50°, with respect to the fiber direction of the first wooden veneer (A) and the second wooden veneer. It is preferable to arrange and laminate the fibers so that the fiber direction of the veneer (A) is oblique to the fiber direction of the veneer (A).

<Wood laminate>
The wood laminate of the present invention has a multilayer structure including a wooden veneer (A) layer and an adhesive (B) layer as essential units. In addition, another layer (C) may be optionally included.
The shape of the wood laminate of the present invention can be selected from various shapes depending on its use. The thickness of the wood laminate is preferably 0.5 to 5.0 cm, more preferably 0.7 to 4.0 cm, and particularly preferably 0.8 to 3.0 cm. Within this range, it tends to have sufficient strength.

The number of wooden veneer (A) layers in the wood laminate of the present invention is variously selected depending on the thickness and shape of the wood laminate, and examples include 2 to 10 layers, 3 to 8 layers, 4 to Examples include 6 layers. The types and shapes (including thickness) of the plurality of wooden veneer (A) layers included in the wood laminate may be the same or different.

The number of adhesive (B) layers in the wood laminate of the present invention is variously selected depending on the thickness and shape of the wood laminate, and examples include 2 to 10 layers, 3 to 8 layers, and 4 layers. ~6 layers etc. The types and shapes (including thickness) of the plurality of adhesive (B) layers in one wood laminate may be the same or different.

The layered structure of the wood laminate of the present invention is that the wooden veneer (A) layer is "A ₁ , A ₂ , A ₃ . . .", and the adhesive (B) layer is "B ₁ , B ₂ , B ₃ ...", and other layers are expressed as "C ₁ , C ₂ , C ₃ ...", for example, "A ₁ /B/A ₂ ", "A ₁ / B ₁ /A ₂ /B ₂ /A ₃ ”, “A ₁ /B ₁ /A ₂ /B ₂ /A ₃ /B ₃ /A ₄ /B ₄ /A ₅ ”, “A ₁ /B ₁ /C Any layer structure may be adopted, such as ` <sub>`1</sub> '', `` <sub>A1</sub> / <sub>C1</sub> / <sub>B1</sub> / <sub>C2</sub> / <sub>A2</sub> '', or `` _A1 / _B1 / _C1 / _B1 / _A2 ''.

<Molded object>
Molded objects obtained using the wood laminate of the present invention include, but are not particularly limited to, stationery, accessories, toys, furniture, automobile parts, and the like.

EXAMPLES The present invention will be explained in more detail below using Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

First, wooden veneer A1, wooden veneer A', adhesive sheet B1, and adhesive sheet B2 were prepared.

<Wooden veneer layer>
・Wooden veneer A1
A Sitka spruce veneer (length 20 cm x width 15 cm x thickness 0.8 mm, air-dried density 0.37 g/cm ³ ) having a breaking elongation of 2.1% in the fiber direction was produced. The manufacturing method and the method for measuring elongation at break are as follows.
(Production method)
A commercially available Sitka spruce veneer (length 20 cm x width 15 cm x thickness 0.8 mm) was subjected to the following processing steps (A) to (C) to produce wooden veneer A1.
(A) A veneer was wound around a steel rod having a diameter of 50 mm and a length of 500 mm, with the front and back sides of the veneer being wound in the same direction as the diameter direction of the steel rod and the fiber direction of the veneer.
(B) Next, the veneer treated in step (A) was wrapped around the steel rod used in step (A) so that the diameter direction of the steel rod and the direction of the veneer fibers were 45° on each of the front and back sides.
(C) Using a steel rod with a diameter of 30 mm and a length of 500 mm, the steps (A) and (B) were performed again.
Note that no slits due to cracks or cuts were generated in the wooden veneer A1 obtained by the above manufacturing method.

(Elongation at break in fiber direction)
The elongation at break in the fiber direction was measured according to the tensile test of JIS K7164. First, a test sample was created from a wooden veneer A1 following the shape of the test piece 1B described in JIS K7164. The test sample has the shape shown in Fig. 5, total length I ₃ = 100 mm, parallel part length I ₁ = 30 mm, distance between gauge lines L ₀ = 12.8 mm, thickness h = 0.8 mm, parallel part width b ₁ = The width of the grip was 15 mm, and the grip width b ₂ was 25 mm.
Then, the test sample was pulled in the fiber direction under conditions of a temperature of 20 ± 1°C, a humidity of 60 ± 10%, and a pulling speed of 1 mm/min, and the elongation rate at break (fiber direction elongation at break) was determined. I asked for it. The results are shown in Table 1.

(vertical elongation at break)
The elongation at break in the vertical direction was measured according to the tensile test of JIS K7164. First, a test sample was created from a wooden veneer A1 following the shape of the test piece 1B described in JIS K7164. The test sample has the shape shown in Fig. 5, total length I ₃ = 100 mm, parallel part length I ₁ = 30 mm, distance between gauge lines L ₀ = 12.8 mm, thickness h = 0.8 mm, parallel part width b ₁ = The width of the grip was 15 mm, and the grip width b ₂ was 25 mm.
Then, the test sample was pulled in the vertical direction under conditions of a temperature of 20 ± 1°C, a humidity of 60 ± 10%, and a tensile speed of 1 mm/min, and the elongation rate at break (vertical elongation at break) was determined. I asked for it. The results are shown in Table 1.

・Wooden veneer A'
A Sitka spruce veneer (length 20 cm x width 15 cm x thickness 0.8 mm, air-dried density 0.38 g/cm ³ ) having a breaking elongation of 0.95% in the fiber direction was prepared. The method for measuring the elongation at break in the fiber direction and the vertical direction is the same as that for wooden veneer A1.

<Adhesive layer>
・Adhesive sheet B1
A thermoplastic polyester adhesive [manufactured by Mitsubishi Chemical Corporation: Polyester (trademark registered) SP-180 (resin flow start temperature 103°C, MFR 0.35 g/10 min)] was applied to a 50 μm thick silicone release PET film (Mitsui (Manufactured by Kagaku Tocello Co., Ltd.: SPPET03BU50) A sheet-like adhesive obtained by sandwiching between two release surfaces and pressing to a thickness of 100 μm using a hot press machine heated to 150°C.

・Adhesive sheet B2
Acrylic polymer for adhesive [manufactured by Mitsubishi Chemical Corporation: Coponil (trademark registered) D-505 (Tg calculated by calculating Tg at each weight fraction using the above FOX formula: 1/Tg=W1/Tg+W2/Tg) = -56°C)] and 2 parts of isocyanate crosslinking agent [manufactured by Tosoh Corporation: Coronate (trademark registered) L] using an applicator to apply the adhesive to a silicone release PET film. A sheet-like adhesive (thickness 100 μm) obtained by coating [SPPET03BU50 manufactured by Mitsui Chemicals Tohcello Co., Ltd.], drying at 80°C for 3 minutes, and aging at 40°C for 7 days.

The flow start temperature was measured using a Koka type flow tester (30 kgf/cm ² ), and the MFR was measured according to JIS K7210 (125° C., load: 0.325 kg).

<Example 1>
Six layers of wooden veneer A1 (parallel lamination) and five layers of adhesive sheet B1 were alternately laminated (layer structure: A1/B1/A1/B1/A1/B1/A1/B1/A1/B1/A1), Pressing was performed under the conditions of a press pressure of 0.5 MPa, a heating temperature of 120° C., and a press time of 15 minutes to adhere each layer. The wood laminate obtained by bonding each layer was cured at 105°C for 12 hours and then at 20°C for one week to obtain a wood laminate with a thickness of 8.7 mm.

<Horizontal shear test>
A wood laminate having a predetermined shape was cut out from the wood laminate obtained above to prepare a test sample (the test sample had a total length of 120 mm, a width of 10 mm, and a thickness of 10 mm).
Regarding the test sample, the maximum displacement (mm) and shear modulus of elasticity (kN/mm ² ) was measured. The results are shown in Table 1. In addition, when there was a deviation in the thickness during the preparation of the test sample, the shear modulus of elasticity was calculated using the actual thickness.
(Measurement condition)
Distance between fulcrums: 60mm
Loading speed: 10mm/min
Test temperature: 20℃ and 80℃ (Test samples used were left at the same temperature for more than 6 hours)
Test humidity: humidity 60±10%

<Appearance evaluation test after horizontal shear test>
Appearance evaluation after the horizontal shear test (20°C and 80°C) is performed by visually checking the outermost layer on the tension side and compression side of the test sample after reaching the maximum displacement, and if there is no breakage in the outermost layer, mark it as “〇 ”, and those with breakage in the outermost layer were rated “×”. The results are shown in Table 1 and FIG.

<Example 2>
A wood laminate (thickness: 8.6 mm) was obtained in the same manner as in Example 1, except that adhesive sheet B1 was changed to adhesive sheet B2. The results of each test similar to Example 1 are shown in Table 1 and FIG. 2.

<Comparative example 1>
A wood laminate (thickness: 8.7 mm) was obtained in the same manner as in Example 1, except that the wooden veneer A1 was replaced with a wooden veneer A'. The results of each test similar to Example 1 are shown in Table 1 and FIG. 3.

<Comparative example 2>
A wood laminate (thickness: 8.6 mm) was obtained in the same manner as in Example 1, except that wooden veneer A1 was changed to wooden veneer A', and adhesive sheet B1 was changed to adhesive sheet B2. The results of each test similar to Example 1 are shown in Table 1 and FIG. 4.

From the results shown in Table 1 and each figure, it is clear that by using the wooden veneer (A) of the present invention, regardless of the type of adhesive or the mechanical properties of the wood laminate derived from it, It can be seen that the appearance after applying load and deformation to the laminate is improved. This is thought to be because the use of the wooden veneer (A) having a specific elongation at break (%) in the fiber direction improved the flexibility of the wood laminate as a whole.

Furthermore, in comparing Example 1 and Comparative Example 1, and Example 2 and Comparative Example 2, the maximum displacement and shear elastic modulus in the horizontal shear test did not change significantly. From this, by having the wooden veneer (A) of the present invention have a moderate elongation at break (%), it is possible to improve only the flexibility under load without significantly changing the physical properties of conventional wood laminates. It can be said that

The wood laminate of the present invention can be used in a wide range of applications, such as small items, furniture, veneer plywood for building materials, panel panels, structural plywood, and three-dimensional molding plywood. In particular, it is suitable for use in plywood for three-dimensional molding.

Claims (8)

A wood laminate having a wooden veneer (A) layer and an adhesive (B) layer, wherein the elongation at break in the fiber direction of the wooden veneer (A) is 1.5 to 5.0%. A wood laminate characterized by: The wood laminate according to claim 1, wherein the wooden veneer (A) layer has a thickness of 0.3 to 3.0 mm. The wood laminate according to claim 1 or 2, wherein the wooden veneer (A) is a wooden veneer (A) that does not have a slit of 0.2 mm or more in the thickness direction. The wood laminate according to claim 1 or 2, wherein the wooden veneer (A) is a cellulose-based fibrous structure. The wood laminate according to claim 1 or 2, which is for three-dimensional molding. The method for producing a wood laminate according to claim 1 or 2, comprising a step of applying pressure to the wooden veneer (A) layer and the adhesive (B) layer to bond them together. . The method for producing a wood laminate according to claim 6, wherein the adhesive (B) layer is a sheet-like adhesive (B) layer. A molded article obtained from the wood laminate according to claim 1 or 2.