JPH09254318A - Wood reinforcing carbon fiber prepreg and carbon fiber reinforced wood - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon fiber prepreg wherein excellent adhesion and long usable life are provided, and rigidity and elastic modulus which are imparted to carbon fiber can be given by a high ratio to reinforced wood. SOLUTION: This wood reinforcing carbon fiber prepreg is provided by being impregnated with a mixed resin of 3-150 poise viscosity at 25 deg.C. The mixed resin contains at least one kind of resin selected from a resorcinol resin and a resol type phenol resin, and formaldehyde as a curing agent or an inorganic acid or organic acid as a curing catalyst.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbon fiber prepreg for wood reinforcement and a carbon fiber reinforced wood reinforced by this prepreg, and more specifically, carbon impregnated with a specific resin excellent in adhesion to wood. A carbon fiber reinforced wood in which a sheet or strand of a fiber prepreg and the prepreg are attached to the surface of a single wood or a plurality of boards or laminated wood composed of veneers, or between or between the boards to integrate them It is a thing.

[0002]

2. Description of the Related Art Conventionally, laminated wood, which is obtained by laminating a single piece of wood, a sawing board or a small square wood long-machined in the fiber direction with the fiber directions parallel to each other with an adhesive, is mainly used in construction. It is used as a frame material such as columns and beams, and is also used recently for wooden bridges and large domes.

In particular, the laminated wood has a high degree of freedom in terms of size and shape because it is made of laminated lumber and small square timber, and has little variation in product strength, drying cracks, deviations, etc., and can easily manufacture bent materials. Has the excellent characteristics of.

However, when these laminated lumbers are used in large-scale buildings and structures, it is necessary to increase the rigidity and strength of the laminated lumbers, so that it is necessary to increase the thickness of the laminated lumbers. It has been proposed to use a reinforced single wood or a reinforced laminated wood in which carbon fibers having high rigidity and strength are bonded via an adhesive in order to make the ceiling of a structure low or to make it higher than necessary.

In particular, such carbon fiber reinforced wood and carbon fiber reinforced laminated wood have a method of arranging carbon fibers on the surface of a wood coated with an adhesive so that the adhesive is impregnated between the fibers and is also bonded to the wood. Kaihei 2-26770),
It is made by a method of adhering a prepreg in which carbon fibers are well impregnated with an adhesive (Japanese Patent Laid-Open No. 52-23060), but the former must be processed on site, which complicates the work and secures a workplace. However, carbon fiber prepregs are often used in terms of the possibility of factory production with controlled work in other places and workability.

[0006]

However, these carbon fiber prepregs are inferior in adhesiveness, and the obtained reinforced wood and reinforced laminated wood have low rigidity and strength relative to the amount of carbon fiber used. In addition, there are problems that excessively expensive carbon fiber is used more than necessary and that the adhered layer is peeled off during use. For this reason, the resin used is extremely important.

Epoxy resins are used in carbon fiber composite materials that are widely used today. Although this resin has excellent adhesion to carbon fibers, it has a defect that it is extremely inferior in heat resistance and fire resistance required for wood constructions and structures.

Therefore, resins such as phenolic resins and resorcinic resins are used as adhesives for carbon fiber reinforced wood and laminated wood. These resins not only have sufficient water resistance, corrosion resistance, fire resistance and heat resistance required for wood constructions and structures, but also have excellent adhesion between woods.

However, when a carbon fiber prepreg is made by using these resins, not only is the adhesion between the carbon fiber and the resin or between the carbon fiber and the wood poor, but also the fluidity at the time of bonding with the wood. In addition, there is a problem that it is extremely difficult to obtain a prepreg with a long shelf life having a long pot life, which is essential for controlled factory production.

The inventors of the present invention have conducted extensive studies to solve the conventional problems, and as a result, by using a mixed resin containing a specific resin and a specific curing agent and a curing catalyst to form a carbon fiber prepreg, these The inventors have found that the problems can be solved and have reached the present invention.

That is, the object of the present invention is to use it by adhering it to a single piece of wood or laminated wood, to have excellent adhesion, long pot life, and to enhance the elastic modulus and strength of carbon fiber at a high ratio. It is to provide a carbon fiber prepreg that can be applied to wood and reinforced laminated wood.

Another object of the present invention is to provide a single wood and laminated wood having high rigidity and strength using the carbon fiber prepreg. In addition to expanding the uses of wood for large buildings and structures that could not be done until now, to provide wood and laminated wood reinforced with carbon fiber that is useful for reducing the amount of natural wood used. is there.

[0013]

The present invention is a wood fiber-reinforced carbon fiber prepreg impregnated with a mixed resin having a viscosity of 3 to 150 poise at 25 ° C., and the mixed resin is a resorcinol resin. , A carbon fiber prepreg for wood reinforcement, comprising one or more resins selected from resol-type phenolic resins and formaldehydes as a curing agent or an inorganic acid or an organic acid as a curing catalyst. Gel time at 30 ℃ is 50
This is achieved by a sheet or strand of carbon fiber prepreg impregnated with the liquid mixed resin of not less than a minute. Further, the prepreg is adhered to the surface of a single wood or to a plate or a plate of a laminated wood composed of a plurality of plates or veneers or to a surface thereof, and if necessary, heated and pressurized to be integrated into a carbon fiber. This is achieved by using reinforced wood. According to the present invention, the prepreg is characterized by excellent adhesiveness to wood, flexibility and long work life, and thus high workability.

[0014]

DETAILED DESCRIPTION OF THE INVENTION The present invention is described in detail below. The resin used in the present invention is phenol, cresol,
Xylenol, ethylphenol, chlorophenol,
Phenols or oligomers having one phenolic hydroxyl group such as bromophenol and resorcin,
Phenols / aldehydes = 2/1 to 1 = phenols having two or more phenolic hydroxyl groups such as hydroquinone, catechol and phloroglysinol and aldehydes such as formaldehyde, paraformaldehyde, acetaldehyde, furfural, benzaldehyde, trioxane and tetoxane / 3, preferably 5/4
Known resole type phenolic resin (phenol and formaldehyde initial addition condensation resin) and resorcinol resin obtained by methylolation in the presence of an alkali catalyst such as potassium hydroxide or sodium hydroxide at a molar ratio of 2/5. Is.

A resin having a polystyrene-reduced number average molecular weight of 100 to 2000 by high performance liquid chromatography (HPLC), particularly 150 to 500 is preferable, and a resin having a viscosity at 25 ° C. adjusted to 3 to 150 poises. Is preferred.

Among known organic hardeners used as hardeners such as resorcinol resin and resole phenolic resin, formalin, acetaldehyde, furfural, benzaldehyde, trioxane,
It is preferable to use a resin such as tetraoxane which is mixed with the resin to form a paste or liquid.

Paratoluenesulfonic acid as a curing catalyst,
It is preferable to dissolve in a liquid state by mixing with the resin such as benzenesulfonic acid, xylenesulfonic acid, and phenolsulfonic acid.

Further, in order to uniformly cure the prepreg, a curing agent or a curing catalyst which becomes a uniform liquid at a temperature of 35 ° C. or lower which is a usual prepreg production temperature when mixed resin is particularly preferable.

The carbon fiber used in the present invention is not particularly limited, but the nitrogen content obtained from the polyacrylonitrile fiber is 0.1 to 15% by weight, and the tensile strength is 2500.
The carbon fiber having an elastic modulus of ˜7,000 MPa and an elastic modulus of 150 to 700 GPa is preferable, and particularly, a tensile strength of 3500 MPa or more having a nitrogen content of 3 to 10% by weight and 200 to
Carbon fibers having a modulus of elasticity of 350 GPa and a diameter of 5 to 9 microns are preferable in terms of adhesiveness.

The oxygen / carbon on the surface of the carbon fiber according to the present invention measured by an ESCA surface analyzer (manufactured by Shimadzu Corporation) is 0.1 / 1 to 0.3 / 1, particularly 0.15.
/ 1 to 0.25 / 1 is preferable because the adhesive strength can be increased.

In actual use, the carbon fiber has a fiber diameter of 5 to 9 microns and a number of constituents of 1000 to 300.
A fiber bundle (strand) consisting of 000 fibers is bundled in a desired amount or widened into a sheet for use.

The carbon fiber prepreg according to the present invention is a carbon fiber in a mixed resin in which one or more of the resins are mixed with formaldehyde as a curing agent or an inorganic acid or organic acid as a curing catalyst, and if necessary, an inorganic filler. Is continuously dipped and impregnated so that the mixed resin is 30 to 80% by weight with respect to the carbon fiber, and the volatile matter is dried and wound to form a prepreg strand, or after the drying. The prepreg sheet is produced by winding the fibers of (1) on a drum so as to be parallel to each other.

Alternatively, it is known that a carbon fiber strand arranged in parallel is placed on a resin film of a release paper coated with the resin in advance while being pressed by a roll, and the resin is permeated into the fiber to form a prepreg sheet. Create using the technique.

The carbon fiber prepreg can be handled by a known method such as attaching a powdered inorganic substance such as talc to the surface in the case of a strand or disposing a release paper on one or both sides in the case of a sheet.

It is necessary that the mixed resin is a uniform solution in order to uniformly impregnate the carbon fibers and carry out uniform curing. If it is not uniform, the obtained prepreg may have poor curing or adhesiveness. It is not preferable because it becomes low. Further, when the amount of the mixed resin of the prepreg impregnated with the mixed resin is 30% by weight or less, the adhesiveness to wood is poor, and
When it is 0% by weight or more, handling such as resin dropping from the prepreg becomes difficult, which is not preferable. Especially 40 ~
60% by weight is preferable in terms of adhesiveness and prepreg handleability.

Further, the mixed resin preferably has a viscosity at 25 ° C. of 3 to 150 poises. When the viscosity is 3 poises or less, the resin easily drops from the prepreg, and when it is 150 poises or more, the carbon fibers are impregnated with the resin. Is inferior, which is not preferable. Adjustment of the viscosity can also be performed by adding water.

Further, the gel time of the prepreg impregnated with the mixed resin is preferably 50 minutes or more at 30 ° C., and when it is 50 minutes or less, the prepreg is cured while being transferred to the customer or is stored under normal storage conditions. It is uneconomical because it gradually cures at minus 20 ° C and cannot be stored for 1-2 weeks.

The single wood and the laminated wood in the present invention are not particularly limited as long as they are wood which has been conventionally used. Usually, wood used for buildings such as cedar, cypress, larch, bay pine, spruce, etc. Oak, kiri, zelkova,
Wood used for plywood such as maple, horse chestnut, hoo, cherry, teak, lauan, and spinal can be used.

Bonding of the sheet and strand of the carbon fiber prepreg of the present invention and the single wood and the laminated wood is carried out as follows to integrate them. That is, a single wood, the surface of the laminated wood and the surface of the laminated wood thin plate, if necessary, a resin used in the present invention and a resin mixed with an inorganic acid or an organic acid as a curing agent or a curing catalyst, particularly preferably carbon fiber After the mixed resin used for the prepreg is applied to the surface of the single wood or laminated wood, the carbon fiber prepreg is attached so that the carbon fiber direction is parallel to the fiber direction of the wood. In the case of a laminated laminated sheet, the thin sheet to which the carbon fiber prepreg is attached and several other laminated laminated sheets are laminated with an adhesive by a known method, and then 1 to 15 kg / c.
Heat at a temperature of room temperature to 120 ° C. for 5 to 24 hours under a pressure of m 2.

To bond a carbon fiber prepreg to the surface of a single wood or laminated wood and to make the surface woody, bond other thin wood or woody thin sheet to the outer surface of the carbon fiber prepreg. You can also

The carbon fiber reinforced wood of the present invention can be applied to ordinary single wood and use as a laminated wood,
In particular, it is suitable as an aggregate for schools, gymnasiums, auditoriums, large-scale buildings such as various indoor ball stadiums and domes, houses on the third floor and above, and wooden bridges.

[0032]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist thereof is not exceeded. The gel time used in the present invention is the time required until the maximum torque when the mixed resin containing the resin used for the carbon fiber prepreg and the curing agent is subjected to curing measurement using a curast meter (manufactured by Japan Synthetic Rubber Co., Ltd.). . The bending characteristics and interlayer shear strength of carbon fiber resin composite materials are JIS K7074 and JI, respectively.
The viscosity was measured according to SK7078, and the viscosity was measured by using Rheometer (manufactured by Rheometric Co.). Furthermore, the bending elastic modulus and bending strength of the wood, the laminated wood, and the carbon fiber reinforced wood and the laminated wood were measured according to JISZ2101.

[0033]

Example 1 A strand of carbon fiber "Vesphite (registered trademark) HTA12K" (Toho rayon) having fiber characteristics of single-micron diameter 7 micron, number of fibers 12,000, tensile strength 3890 MPa, and tensile elastic modulus 236 GPa was placed at 20 ° C. Resol type phenolic resin "AH-343" with a viscosity of 35 poises (Lignite)
3 m in a resin bath containing a mixed resin obtained by uniformly mixing and dissolving 82 parts and 18 parts of an organic curing agent "D-5" (Lignite Co.) having p-toluenesulfonic acid as a main component at room temperature.
/ Minute, soaking time 1 minute, adjust the content of resin by squeeze roll to be 45% by weight, and wrap the strands in parallel to a drum with a diameter of 90 cm and a width of 100 cm so that the release paper is wound in advance. After that,
It was dried at 60 ° C. for 1 hour.

The carbon fiber prepreg thus obtained was cut off from the drum to form a prepreg sheet having a width of 100 cm and a length of about 2.8 m and a weight of 300 g / m 2 of carbon fiber. The gel time of this prepreg sheet was measured at 30 ° C. for 150 minutes. It was This carbon fiber prepreg has a depth of 3 mm and a width of 10
Stacked in a mold of 0 mm and length of 100 mm, pressure 1
Thickness of 3m after heat-curing at 0 ℃ / cm2 for 2 hours at 60 ℃
The carbon fiber content in the composite material was 60% by volume when the bending property was measured as a rectangular test piece having a width of 10 mm and a length of 100 mm, which was cut out from the flat plate of the carbon fiber resin composite material of m. The bending strength was 1634 MPa, the bending elastic modulus was 135 GPa, and the interlaminar shear strength was 74 MPa, which was 95% of the value (referred to as a theoretical value) obtained by proportional calculation from the strength and elastic modulus of the carbon fiber itself, which was an extremely excellent value. Here, the theoretical value is a value obtained by Equations 1 and 2.

[0035]

[Equation 1]

[0036]

[Equation 2]

[0037]

[Comparative Example] The average particle diameter was 1 instead of the curing agent used in Example 1.
A carbon fiber resin composite material plate was prepared in the same manner as in Example 1 except that the paraformaldehyde of Example 1 was used, and the properties of the plate were measured in the same manner. The bending strength was 830 MPa, the bending elastic modulus was 118 GPa, and the interlaminar shear strength was 31 MPa.

[0038]

Example 2 One of the carbon fiber prepregs obtained in Example 1 was attached to cedar wood having a thickness of 24 mm, a width of 30 mm and a length of 500 mm with the fiber direction of the carbon fibers parallel to the fiber direction of the wood. The same resin used for the prepreg was applied to both sides of the pasted board, and a board having the same width and length and a thickness of 3 mm was placed on the both sides and adhered under the same pressure and temperature conditions as in Example 1 to bond carbon fibers. Obtained reinforced wood. The bending strength of this carbon fiber reinforced wood is 74 MPa, and the bending elastic modulus is 10 GP.
a. The bending characteristic value is 57 M of the bending strength of the laminated wood obtained by similarly curing and adhering the wood without using the carbon fiber prepreg and using the mixed resin used in Example 1.
Pa, the flexural modulus is much higher than 6 GPa, and the respective proportions of the carbon fiber and the resin and the laminated wood in the obtained carbon fiber reinforced wood, and the respective strengths of the carbon fiber, the cured resin and the wood. It was a value close to a value (referred to as a theoretical value) obtained by proportionally calculating using and the elastic modulus, and was an extremely excellent carbon fiber reinforced wood capable of sufficiently exhibiting the mechanical properties of carbon fiber. In addition, stacking on the mold is easy and labor-free, and the required time was about 1 minute.

[0039]

The carbon fiber prepreg obtained by the practice of the present invention has high strength and rigidity as well as excellent adhesiveness, and has sufficient water resistance, corrosion resistance, fire resistance, heat resistance and long-term storage stability. Therefore, it is possible to efficiently produce lightened and lengthened wood and laminated wood. Also,
The carbon fiber reinforced wood and laminated wood of the present invention can be used for building various large-scale buildings, wooden bridges, domes, etc., and it is also possible to use wood that could not be used because of its low strength and low rigidity, thus saving valuable natural resources. It can be used effectively and is also beneficial for environmental protection.

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[Procedure amendment]

[Submission date] April 26, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Title: Carbon fiber prepreg for wood reinforcement and carbon fiber reinforced wood

Front page continuation (71) Applicant 391004207 Saito Lumber Industry Co., Ltd. 561 Wada-mura, Ogata-gun, Nagano Prefecture (72) Inventor Shigehisa Ishihara 3-23-12 Tenjin, Nagaokakyo-shi, Kyoto (72) Inventor Hiroyasu Ogawa Tokyo 3-9-9 Nihonbashi, Chuo-ku, Toho Rayon Co., Ltd. (72) Inventor Yoshihiro Endo At 234 Takaishi, Kamishikari, Nagaizumi-cho, Sunto-gun, Shizuoka Toho Rayon Co., Ltd. (72) Inventor Isamu Ide 2-5 Tsukikoshinmachi, Sakai-shi, Osaka (72) Inventor Hideo Getsuhito 24, Sukazu Fukami, Jinmeji-cho, Kaifu-gun, Aichi Prefecture (72) Inventor Satoshi Saito 561-Wada-mura, Ogi-gun, Nagano Prefecture

Claims (5)

[Claims] 1. A carbon fiber prepreg for reinforcing wood, which is impregnated with a mixed resin having a viscosity of 3 to 150 poise at 25 ° C., and the mixed resin is a resorcinol resin or a resole phenolic resin. A carbon fiber prepreg for wood reinforcement, comprising one or more resins selected from the group consisting of formaldehydes as a curing agent and an inorganic acid or an organic acid as a curing catalyst. 2. The carbon fiber prepreg for reinforcing wood according to claim 1, wherein the gel time of the mixed resin at 30 ° C. is 50 minutes or more. 3. The carbon fiber prepreg for reinforcing wood according to claim 1 or 2, wherein the mixed resin is liquid. 4. A sheet or a strand made of the carbon fiber prepreg for reinforcing wood according to claim 1, 2 or 3 is applied to the surface of a single piece of wood or a laminated wood made of a plurality of boards or veneers. Carbon fiber reinforced wood that has been attached by pressing on any of the boards or between single boards or on the surface and applying pressure. 5. A sheet or strand of the carbon fiber prepreg for reinforcing wood according to claim 1, 2 or 3, which is a surface of a single piece of wood, or a laminated wood comprising a plurality of boards or a single board. Carbon fiber reinforced wood that is integrated by heating, pressing and adhering between or between the boards or veneers.