Stock material or miscellaneous articles – Composite – Of aldehyde or ketone condensation product
Reexamination Certificate
2001-04-12
2003-07-22
Kiliman, Leszek (Department: 1773)
Stock material or miscellaneous articles
Composite
Of aldehyde or ketone condensation product
C428S532000, C428S535000, C428S536000, C428S537100
Reexamination Certificate
active
06596408
ABSTRACT:
FIELD OF THE INVENTION
This invention relates a wood reinforcing material for strengthening wood material and a reinforced wood material reinforced with the wood reinforcing material.
BACKGROUND OF THE INVENTION
Heretofore, single wood materials or so-called bonded wood materials formed by bonding sawn woods or small square lumbers cut longitudinally in the direction of fibers with the direction of the fibers being in parallel with each other have been used mainly as frame materials such as post and beams in buildings, as well as for wooden bridges or large scale domes.
Particularly, since the bonded wood materials are assembled from sawn woods and small square lumbers, they have excellent characteristics such as high degree of freedom for the size and dimension, less variation in the strength of products, cracks or errors cause by drying, as well as capable of easily manufacturing bent materials.
However, when such bonded wood materials are used for large buildings and structures, since the rigidity and strength of the bonded materials have to be increased, it is necessary to increase the thickness for the bonded materials and, as a result, this causes problems such as lowering of ceilings in the buildings and structures, or.unnecessary increase in the height of roofs.
Therefore, for providing the bonded wood materials and single wood materials with high rigidity and strength and also providing sufficient water proofness, corrosion resistance, fire resistance, heat resistance and adhesion required for the buildings or structures of woods, it has been proposed to bond carbon fibers by adhesives such as phenolic resins or resorcinolic resins to obtain reinforced wood materials such as carbon fiber-reinforced single wood materials or carbon fiber-reinforced bonded wood materials.
As one of methods for manufacturing such reinforced wood materials, Japanese Laid-Open No. 230904/1991, for instance, discloses a method of coating an adhesive on the surface of wood material, disposing carbon fibers thereon and impregnating an adhesive between the fibers and also bonding the same with the wood material (Prior Art 1).
As another method of manufacturing the carbon fiber-reinforced single wood material or carbon fiber-reinforced bonded wood material, Japanese Patent Laid-Open No. 108182/1978 proposes a method of using a so-called prepreg in which an adhesive is previously impregnated sufficiently to carbon fibers and bonding the same to a wood material (Prior Art 2). This method enables working in various places and is suitable also in view of the fabricability and, accordingly, has been used generally.
The present inventors have proposed a wood reinforcing material by bonding a wood reinforcing carbon fiber prepreg and a wooden sheet in Japanese Patent Laid-Open No. 254319/1997 (Prior Art 3). In this cited invention, release paper is not necessary, the resultant wood reinforcing material has high strength and high rigidity and can obtain high stable properties regarding adhesion performance between the wooden sheet and the wood material, or adhesion performance between the wooden sheet and carbon fibers.
In the Prior Arts 1 and 2, since the wood material is natural products having different natures depending on the growing environments, it involves a problem that adhesion fluctuates when the carbon fiber prepreg and the wood material are bonded. Further, for ensuring the bondability, it requires a frequent control for selecting and optimizing the state such as solid, semi-solid or liquid and amount thereof, which leaves various problems with view point of cost performance and quality.
In the Prior Art 2 described above, since carbon fiber prepregs are generally transported or stored being rolled or stacked into sheets, so that release paper is disposed on one surface or both surfaces of the prepreg. However, when bonding with the wood materials, troublesome and time consuming fabrication operations are necessary such as for removal of the release paper, as well as removed release paper yields wastes and the use of prepregs have resulted in environmental contamination.
In the Prior Art 3 described above, the wooden sheet itself causes shear failure in the bending failure test and sufficient reinforcing effect can not always be obtained.
The present inventors have intended to provide a wood reinforcing material which is applied to wood materials or bonded wood materials for reinforcement capable of overcoming the problems in the prior art, as well as a reinforced wood material in which the wood reinforcing material is applied to the surface of the wood material or to the inner layer of the bonded wood material.
Specifically, this invention intends to provide a wood reinforcing material excellent in bondability with the wood material and handlability, not causing environmental contamination such as forming wastes of release paper, and having a sufficient reinforcing effect for the wood material, as well as reinforced wood material.
More specifically, this invention intends to provide a wood reinforcing material of reducing fluctuation of adhesion performance, strength and rigidity caused by variation in wood materials as natural products and minimizing the complexity in view of the working and minimizing the wastes, as well as having high bondability, strength and rigidity, as well as a reinforced wood material applied with the wood reinforcing material.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the foregoing problems.
In accordance with a wood reinforcing material of this invention, a phenol resin-impregnated sheet with a degree of cure of 70% or more and 95% or less in which a porous sheet is impregnated with a phenol resin is disposed on the surface of a carbon fiber-reinforced thermosetting resin sheet.
Further, in accordance with a reinforced wood material of the invention, the wood reinforcing material is integrated and cured by way of a phenol resin-impregnated sheet on the surface of a wood material.
In the wood reinforcing material of the invention, since a phenolic resin-impregnated sheet with a degree of cure of 70% or more and 95% or less is disposed, it forms a molding product showing excellent adhesion to a wood material to be reinforced and also free from stickiness, so that it does not require release paper. Accordingly, the reinforced wood material according to this invention which is reinforced by applying the wood reinforcing material of the invention to the surface of the wood material has a feature of high strength, high rigidity and high shear strength.
Carbon Fiber-reinforced Thermosetting Resin Sheet
A carbon fiber-reinforced thermosetting resin sheet as a constituent factor of the wood reinforcing material of this invention is reinforced with carbon fiber in the thermosetting resin as reinforcing fibers.
There is no particular restriction on the carbon fibers and carbon fibers obtained from polyacrylonitrile fibers with a nitrogen content of 0.1 to 15% by weight, a tensile strength of 2,500 to 7,000 MPa and a modulus of elasticity of 150-700 GPa are preferred and, particularly, carbon fibers of 5 to 9 mm diameter containing 3 to 10% of a nitrogen content and having 3,500 MPa or more of tensile strength and 200 to 350 GPa of modulus of elasticity are preferred in view of the adhesion.
Further, those in which the oxygen/carbon ratio of 0.01/1 to 0.3/1, particularly, 0.01/1 to 0.25/1 at the surface of the carbon fibers of this invention by an ESCA surface analyzer (manufactured by Shimazu Seisakusho) are preferred since the adhesion strength can be improved.
It is desired that carbon fibers with the fiber diameter of from 5 to 9 mm and fiber strands comprising the fibers by the number of 1,000 to 300,000 are used by being bundled or spread in a sheet-like shape in an amount, with no particular restriction only thereto.
The form of the carbon fiber may be a multi-directional sheet such as woven or non-woven fabrics or linear materials such as uni-directionally oriented sheets or rovings.
Kinds of the thermosetting resins reinforced with
Endoh Yoshihiro
Getto Hideo
Ide Isamu
Ishihara Shigehisa
Ogawa Hiroyasu
Jordan and Hamburg LLP
Kiliman Leszek
Toho Tenax Co., Ltd.
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