JP5997696B2 - WOOD COMPOSITE MATERIAL, PROCESS FOR PRODUCING THE SAME AND PRODUCT CONTAINING THE SAME - Google Patents

Description

  Embodiments relate to a wood composite suitable for the production of a support element, a method for producing the same and a product comprising it.

  Material weight is an important material parameter in a support element that is subject to bending. A low density material with sufficient strength and rigidity has advantages over a high density material with the same mechanical properties because the warpage caused by its own weight is small.

  The reduction in density that reduces the weight of the material while simultaneously maintaining stiffness and strength provides many advantages in ergonomics and logistics. The advantages and labor savings associated with lower weight begin with initial response, e.g., transportation and lifting equipment personnel, response to design and energy consumption, e.g. handling to end use such as assembly of structural parts, or Continue at all stages through further processing and, if applicable, continue until disposal.

  In recent years, various attempts have been made to reduce the density of wood composites. The basic idea behind almost all of the lightweight wooden frames that are construction materials is the multilayer sandwich structure. In this manner, the core material primarily transmits shear and normal drag, and in the covering, a strong, stiff material or a non-hollow wood element absorbs pressure and tension.

  And in the woody material industry, for example, paper honeycomb plates that have been on the market for decades are now being reviewed through new developments and improvements. These materials are very low density but cannot be used for support purposes in that they lack their mechanical properties and water resistance.

  Improved properties have been obtained with lightweight materials having a sandwich structure and a core resembling a foam. However, due to the high shear load applied to the low density core material, the shear strength against bending load is lacking and severe deformation occurs. Furthermore, the strength properties are hardly applicable for use as a support element.

  In the production of wood composites made of current macrofibers and binders, twisted yarns, particles or fibers are embedded in the binder. Subsequently, the binder is cured by a pressure plate that is compressed and heated through a compression process. In this process, large compression occurs particularly at the edges of the pressure plate. And ordinary plywood, fiberboard, plate materials such as OSB (Oriented Strand Board), and special wood materials such as Quetschholz, scrimber, TimTek, Srimtec, SST are more or less in the thickness direction of the plate Has a unique density profile. In cases that lack the majority of the density profile, all materials are strongly compressed or are very low density boards (eg, light wood wool panels, low density plywood, etc.) due to their low strength It cannot be compared with materials for support purposes.

  As mentioned above, normal board materials and special wood materials such as Quetschholz, Scrimber, TimTek, Srimtec, SST are subject to significant compression during the manufacturing process. This compression treatment is accompanied by compression (cell destruction) of the cellular tissue of the tree in addition to densification. Such deformation is partially restored by absorbing moisture and due to hygroscopicity of the tree and cell wall expansion. However, it involves a strong expansion of the compressed part and the entire plate.

  Further, in this manufacturing method, it is difficult to introduce heat for curing the plate material into the panel due to compression. For this reason, in these manufacturing methods, in order to ensure appropriate heat conduction, steam shock (steam shock) is usually used. However, by using steam shock, the macrofibers and / or binders have a lot of (residual) moisture. Without the so-called steam shock, the technical implementation of the production of the plate material (particularly the production of the low-density plate material) is only difficult.

  Despite many attempts, wood composites that combine low density and stiffness suitable as support elements and that can avoid the disadvantages of compression in their manufacture are not commercially available. Therefore, it aims at enabling utilization of such a wood composite material.

The object is according to the invention to have a density of 200 to 550 kilograms (kg) per cubic meter (m ³ ) and a stiffness measured in a 4-point bending test according to EN 789 of 4000 to 12000 megapascals (MPa). ) Is achieved by the wood composite. The wood composite material includes macrofibers having a slenderness ratio (length ratio to fiber thickness) exceeding 20, and a binder, and the binder includes a foam structure.

The wood composite material of the present invention has a density of 200 to 550 kg / m ³ , preferably 300 to 550 kg / m ³ . The rigidity measured by a 4-point bending test according to EN789 is 4000 to 12000 MPa, preferably 5000 to 12000 MPa, more preferably 6000 to 12000 MPa. In a more preferred embodiment, the wood composite has a stiffness of 300-550 kg / m ³ and 6000-12000 MPa.

  The wood composite of the present invention comprises wood macrofibers with a slenderness ratio (ratio of length to fiber thickness) of greater than 20.

Macro fibers used are preferably has a length of 100-400 mm (m m), more preferably 150 to 300 m m. However, it will be apparent to those skilled in the art that the fibers used cannot be excluded for production reasons to include a certain amount of shorter fibers.

  The wood composite of the present invention further includes a binder having a foamed structure in a cured state. The binder preferably has a foamed structure mainly including micropores. More preferably, 90-95% of the micropores have a size measured using a microscope in the cross section of the material in the range of 30-500 micrometers (μm), more preferably 50-300 μm.

In a preferred embodiment, the binder used in the wood composite of the present invention has a density of 30 to 300 kg / m3, preferably 80 to 200 kg / m3 when foamed in a volume unconstrained state. Form a foam.

In order to obtain the density by foaming without volume restriction, an unreacted binder is poured into a container having an opening on the upper surface. The binding material is foamed by a chemical reaction and can be freely expanded through the opening. And after hardening, the overflowing foam is scraped off with a knife. The density of the unfoamed binder is calculated from the pre-measured volume, the container tare weight, and the weight of the container filled with foam.

  In the present invention, a binder that forms a foam structure having closed pores is preferably used. In the wood composite of the present invention, the fibers are substantially entirely contained in the foam, and the voids between the fibers are substantially filled with foam, so the closed pore structure of the foam is intruded by moisture. Reduce or completely prevent. As a result, wood composites exhibit advantageous properties when exposed to moisture, such as little expansion.

  Thereby, the expansion | swelling of the wood composite material of this invention is suppressed remarkably compared with a normal wood material when exposed to moisture. Normal woody material expands significantly compared to the expansion of the solid wood used, which is below or below the expansion range of non-hollow wood. For example, when using spruce fibers, the measured thickness expansion according to DIN 52364 is between 2.7% and 6%. And according to EN317, it is between 1.5% and 5%. In contrast, the measured value of the expansion of non-hollow spruce according to DIN 52364 is also 4-6%. On the other hand, the corresponding plywood or OSB expansion measurements show 7% to 30%.

In order to further reduce the expansion of the wood composite, the fibers used can be modified by suitable methods before further processing. Such methods are, for example, acetylation, impregnation with a suitable resin or chemical such as melamine resin or DMDHEU, thermal denaturation, or other known means of inhibiting expansion. This reduces fiber expansion due to moisture absorption and considerably reduces the overall expansion of the wood composite. An expansion value of 2% to 4% or less can be obtained. Since the macro fiber used for the wood composite material according to the present invention is thin, it can be easily impregnated. On the other hand, modification of non-hollow wood may fail due to lack of wood impregnation.

  In addition, chemical methods may require heat treatment after wood impregnation. Again, the small dimensions of the macrofibers used in the present invention show an advantage over solid wood because heat wraps around the entire tree faster. The heat treatment required for such deformation can be advantageously integrated partially or entirely into the manufacturing process of the wood composite according to the present invention.

  A polymer-based binder is preferably used as the binder according to the invention. For example, epoxy resin, isocyanate (including polyurethane), melamine, urea, phenol resin foam or a mixture thereof is used. Polyurethane systems, for example single-component or multi-component polyurethane systems, in particular two-component polyurethane systems, are more preferably used. Also, a thermoplastic foam such as polystyrene (for example, EPS or EPX) can be used.

  In a further preferred embodiment, the wood composite according to the invention can additionally contain particles such as, for example, iron oxide particles that can be excited by an electromagnetic field. When using such particles, an electromagnetic field (eg, induction, electromagnetic waves, high frequency, radiation, etc.) can be applied to initiate and / or promote the foaming and curing process of the binder. . The particles can be effectively included in the binder prior to the production of the wood composite. Moreover, you may insert separately.

  Also, heat, hot air, or steam may be used to initiate and promote and / or promote the foaming and curing of the binder.

  Furthermore, the wood composite material according to the present invention is suitable, for example, as a foaming agent, a filler, a pigment, a reinforcing fiber (nano, micro or macro fiber), a fireproofing agent or a wood protecting agent, and a chemical for suppressing expansion. Various additives may be included. These additives may be added to the binder or may be included separately in the material. As known to those skilled in the art, such additives impart special properties to the wood composite, such as increasing hardness or shear strength, durability, and moisture resistance.

The wood composite material according to the present invention can be obtained by a method including the following steps.
a) Manufacture of macrofibers b) Alignment of macrofibers c) Application of binders d) Compression e) Foaming of binders

  In the method according to the invention, the binder is applied to the aligned macrofibers (in order of steps a, b, c, d and e). Further, a binder may be applied before the macro fibers are aligned (in order of steps a, c, b, d, and e).

The method can be advantageously carried out continuously by, for example, a belt press method .

  To produce the wood composite of the present invention, the macrofibers are dried and aligned on a press plate or press mold so that they are mostly oriented in one direction (parallel). The binder is applied between and / or on the aligned macrofibers. The application of the binder can be carried out using methods established in the wood industry such as sprays, gluing devices or chip mixers.

  In a preferred embodiment of the method according to the invention, the time for foaming the binder is controlled so that the process starts mainly only after the press is closed. That is, the binder system is chemically controlled to delay the start time of foaming so that the press or press mold can be closed before expansion due to foaming becomes significant.

  When closing the press or press mold, the macrofibers are preferably only subjected to minimal compression so that the density of the wood composite produced does not deviate significantly from the density of the wood used. As a result, an expansion value within or below the expansion range of the wood used is obtained. This is an important advantage in comparison with conventional woody materials, which are mostly highly compressed and largely expand over the wood used when exposed to water.

  Inside the closed press mold or press, the molding pressure applied from the outside works, while the binder penetrates almost the entire macrofiber network and wets the surface of the macrofiber almost completely. The molding pressure is generated from the inside through the foaming of the binder. As a result, the macrofibers are surrounded by the binding substrate, thereby being well protected from moisture absorption.

  As the binder is introduced into the macrofiber network by its expansion, a very homogeneous material with uniform density is formed. There, substantially all void spaces are filled with a foam structure and the fibers are substantially completely surrounded (sealed) by the foam.

  Furthermore, the method according to the present invention is advantageous in that it provides a heat supply with negligible initial curing, particularly when a two-component polyurethane system is used as the binder. The required heat can be supplied by mild preheating of the macrofibers (for example, 30-90 ° C, preferably 50 ° C).

  Since the bonding material contacts the macrofibers just prior to its curing, essentially 100% of the bonding material is available for chip bonding and sealing.

  If the binder system can be controlled to fully cure in the compressor, the press can be opened quickly. The panel of wood composite according to the invention is not destroyed by so-called splits, even if it is not completely cured. Even with a subsequent curing process, the wood composite according to the present invention only expands somewhat.

  The wood composite according to the present invention is suitable for all products produced from solid or wood materials such as chipboard or OSB. When the wood composite material according to the present invention is used, the weight of the product produced by this method can be reduced due to its low density.

The use of the wood composite according to the present invention is advantageous, especially for products where dimensional stability and stiffness during exposure to moisture are important, apart from weight. From the point of view of unprotected outdoor use, such products include
Formwork products such as form girders and parts such as flanges and webs. Coated or uncoated formwork plates and members such as core material or covering layers. Working and defensive scaffolds. -Formwork products for forming or supporting treads, which are circular or flat in 1D, 2D and 3D shapes-Formwork or structures to be removed That part that remains

Other products advantageously produced from the wood composite according to the present invention include:
· Wooden construction girders made of non-hollow materials or with cavities, or parts thereof such as flanges, webs (advantages; low weight, defect-free homogeneity such as bumps found in solid wood Choices in girder manufacturing (I-beam or other optimized cross-section similar to metal girders)
• Wooden structural panels and furniture structural panels (advantages; combined with low weight and economical manufacturing capacity, with properties similar to plywood in terms of strength, expansion and moisture resistance)
・ Wood structure panel parts (covering material, core material)
A core material made by cutting a block containing fibers arranged in parallel in a direction perpendicular to the fibers, mostly containing fibers oriented vertically (advantage: low weight, substantially thickness direction) No economic expansion, economical productivity (eg, replacement of balsa wood with exposed fiber ends)
Acrylic with a durable covering made of a suitable material, such as veneer, with a sandwich panel, plywood or core material with a longitudinal or flat grain, especially made from lightweight macrofiber core material Panels can be used-Thick wood panels with a thickness of 5 cm to 20 cm used for walls or ceilings (Advantages: weight, heat insulation, strength, moisture resistance)
-Thick wood panel with cavities (Advantages: Same as above, somewhat lighter, material savings)
· Multiple parts made from non-hollow materials used for structural parts, windows, doors and furniture, or multiple parts with cavities (advantages: can be manufactured without wasting material, weight, strength)
・ Panels, beams, and parts for vehicle manufacturing (Advantages: weight, strength, moisture resistance)
-Wooden structure in vehicle manufacturing, and round and flat 2D and 3D molded parts for interior decoration and furniture (advantages: virtually any shape can be manufactured, strength, weight)
Is included.

  The macrofibers are dried by warm air (50 ° C.) to a timber humidity of about 12% and stored for several days at an ambient temperature of 20 ° C. and a relative humidity of 65%. Arrange 210 g of macrofibers as parallel as possible to each other. 50% of the fibers are placed in an aluminum mold (30 × 12 cm) heated to 50 ° C. and uniformly wetted by 60 g of two-component polyurethane (RAMPF No. 80 L86 / 4-1). The remaining 50% of the fibers are then placed in the mold and the mold is closed so that the inserted macrofibers are compressed to a height of 16 mm. The two components of water and polyurethane available in the wood react chemically and foam strongly. After 30 minutes, the foam is fully cured and the wood composite can be removed from the mold.

Claims (15)

Slenderness ratio (ratio of length to thickness of the fibers) exceeded 20, and macro fibers aligned in one direction,
A binder comprising a foam structure;
With
Having a density of 200 kg / m ³ or more and 550 kg / m ³ or less,
A wood composite material having a flexural modulus measured by a four-point bending test according to EN789 of 4000 MPa to 12000 MPa.   2. The binder according to claim 1, wherein the binder mainly has a foam structure having micropores, and the micropores of 90% or more and 95% or less have a size of 30 μm (μm) or more and 500 μm or less. Wood composite material. ^3. The woody composite material according to claim 1, wherein the binder forms a foam having a density of 30 kg / m ³ or more and 300 kg / m ³ or less under a foaming condition without volume restriction.   The woody composite material according to any one of claims 1 to 3, wherein the binder includes polyurethane.   The woody composite material according to any one of claims 1 to 4, further comprising particles excited by an electromagnetic field.   The woody composite material according to any one of claims 1 to 5, wherein the expansion in the thickness direction according to EN317 is 5% or less.   The woody composite material according to any one of claims 1 to 6, wherein the macro fiber is modified by acetylation, impregnation using melamine resin or DMDHEU, and heat denaturation. Forming macro fibers,
Aligning the macrofibers in one direction ,
Apply the binder,
Close the press machine
The method for producing a wood composite material according to claim 1, wherein the binder is foamed.   The manufacturing method according to claim 8, wherein the binding material includes a system adjusted so that a foaming process is started mainly only after the press is closed.   The method according to claim 8 or 9, wherein the foaming and curing process is initiated and promoted by an electromagnetic field, or one of them.   The manufacturing method according to claim 10, wherein particles capable of being excited by an electromagnetic field are applied in addition to the binder.   The manufacturing method according to claim 11, wherein the particles are included in the binder.   The method according to claim 8 or 9, wherein the foaming and curing process is initiated and / or accelerated by heat, hot air or steam.   The manufacturing method as described in any one of Claims 8-13 performed as a continuous process using a belt press method. Formwork products and parts thereof; coated or uncoated formwork panels, and parts thereof; one-dimensional, two-dimensional or three-dimensional shapes for forming or supporting a working or protective scaffolding tread Round or flat formwork products; formwork or parts remaining in structures; wood girders for construction or parts thereof; wood structure panels; furniture construction panels; wood panels; parts; A product comprising a wood composite according to any one of claims 1 to 7, selected in particular from:, beams and parts; and molded parts.