JPH04327249A - Braid for reinforcing frp and tubular fiber-reinforced composite material - Google Patents

Abstract

PURPOSE:To provide a reinforcing braid having good workability in a process for forming tubular molded products comprising FRP, and the tubular FRP using the braid and having high physical properties. CONSTITUTION:A reinforcing braid comprising a round three-axial braid made of fibers (3, 3a, 3b) in the longitudinal direction and of fibers (1,2) arranged in the bias direction having an angle of + or -alpha deg. based on the longitudinal direction, the fibers (3, 3a, 3b) and the fibers (1, 2) comprising reinforcing fibers and elastic fibers, respectively, and a tubular FRP using the braid.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to reinforcing braids for fiber-reinforced composite materials such as fiber-reinforced plastics (FRP), and particularly to reinforcing braids suitable for use in the molding of tubular fiber-reinforced composite materials, and further relates to reinforcing braids suitable for use in molding tubular fiber-reinforced composite materials. This invention relates to a tubular fiber-reinforced composite material molded using reinforcing braid, which is used to construct shafts, tennis racket frames, bicycle frames, etc.

0002

[Prior Art] When molding tubular FRP that constitutes fishing rods, golf shafts, tennis racket frames, bicycle frames, etc., core materials such as rod-shaped foam, rubber tubes, and metal mandrels are used to form hollow circles made of reinforcing fibers. It is often inserted into a braided cord, impregnated with resin, and then placed in a mold and molded.

[0003] When a normal round braid is used in this forming, the reinforcing fiber threads are oriented only in the bias direction of ±α°, which increases the torsional strength and rigidity of the tubular body, but the length of the tubular body increases. Since the reinforcing fibers are not oriented in the horizontal direction, the bending strength and rigidity are low. In order to provide reinforcement against bending, a reinforcing fiber fabric is sometimes cut and wrapped around a braid so that the reinforcing fiber threads are oriented in the length direction of the tubular body, but it is difficult to fix the fabric, and the fabric may unravel, resulting in poor workability during molding. bad. Further, there is a problem that the surface of the tubular body becomes uneven at the lap portion of the wound fabric, and there are parts with a large amount of fiber, making it impossible to obtain a tubular body with uniform physical properties.

[0004] On the other hand, a triaxial round braid is known in which the reinforcing fiber threads extend in the length direction and the bias direction of ±α°, but since the reinforcing fiber threads in the three directions intersect with each other,
There were problems in that the bending of the reinforcing fiber yarn became large and stress concentration occurred when FRP was made, and FRP with a high fiber volume content could not be obtained, resulting in only a heavy and low-strength tubular body.

[0005] Furthermore, when forming a tubular body, when a core material is covered with a braid or a triaxial braid with fibers oriented in the normal bias direction, the braid is made to have a diameter larger than the outer diameter of the core material. However, after insertion, the expanded braid must be manually corrected so that it comes into close contact with the core material, and setting the braid to the core material is complicated. Further, when a normal triaxial braid is expanded in the radial direction, the length direction conversely contracts, so there is a problem that the reinforcing fiber threads in the length direction meander.

Furthermore, since fiber-reinforced composite materials have extremely high anisotropy, sheet-like prepregs are laminated and molded so that the fibers are oriented in a predetermined direction. For example, golf shafts are made by cutting prepreg in which fibers are arranged parallel to one direction onto a tapered mandrel so that the fibers are oriented in the axial direction of the shaft, and in a bias direction of ±45° with respect to the axial direction. Prepare prepregs cut to face the surface, wrap them alternately around a mandrel, and heat and pressurize them to shape them. However, since the mandrel is tapered and the prepreg fibers are arranged in parallel, all of the prepreg fibers that are cut to face the axial direction of the shaft do not face in the axial direction, which affects the characteristics of the reinforcing fibers. The current situation is that they are not able to demonstrate their full potential. In order to solve this problem, Japanese Patent Laid-Open No. 51-8
No. 0369 proposes a prepreg in which fibers are arranged radially, but manufacturing such a prepreg is troublesome, and it is difficult to precisely orient the fibers.

[0007]

[Problems to be Solved by the Invention] An object of the present invention is to solve the above-mentioned problems and provide a reinforcing braid that is easy to work with when forming a tubular body, and a tubular fiber-reinforced composite material using the same that has high physical properties. Our goal is to provide the following.

[0008]

[Means for Solving the Problems] In order to achieve this object, the reinforcing braid of the present invention is a triaxial round braid consisting of threads in the length direction and a bias direction of ±α° with respect to the length direction. In braided cords, the threads in the longitudinal direction are made of reinforcing fiber threads,
The yarn in the bias direction of ±α° is made of an elastic yarn.

In the reinforcing braid described above, the elastic yarn is made of, for example, a crimped yarn, and the crimped yarn is braided with the reinforcing fiber yarn in a crimped state. Alternatively, the elastic threads are constructed from polyurethane fibers.

[0010] Furthermore, the tubular fiber-reinforced composite material of the present invention includes:
It is molded using the reinforcing braid constructed as described above.

[0011] The reinforcing braid will be described in detail with reference to the drawings. FIG. 1 shows one embodiment of the reinforcing braid of the present invention, and is a partially enlarged plan view of a three-axis circular braid. The yarn is aligned with the length direction of the braid ±α° (α is about 30 to 60)
It has a configuration of triaxial braids arranged in three directions including the bias direction. The yarns in the two directions in the bias direction of ±α° are made of elastic threads, and the elastic threads 1 in the +α° direction alternately intersect with the elastic threads 2 in the -α° direction, and similarly, the elastic threads in the -α° direction Thread 2
are alternately intertwined with elastic threads 1 in the +α° direction. A braided cord structure in which two elastic threads 1 and 2 in two directions are alternately intersected in this way is generally called a two-way skip structure. On the other hand, the reinforcing fiber yarns 3 extending in the length direction of the braid are arranged at equal intervals in the circumferential direction of the braid and are located between the elastic threads 1 and 2. The reinforcing fiber yarn 3a is connected to the elastic yarn 1 below the elastic yarn 2.
The reinforcing fiber thread 3b located above and adjacent to the reinforcing fiber thread 3a is located below the elastic thread 1 and above the elastic thread 2, and this relationship is alternately repeated so that the elastic thread becomes the reinforcing fiber. It holds the thread together. As a whole, an even number of reinforcing fiber threads 3 are arranged, and the braid has a tubular shape.

[0012] In Fig. 1, the case where the elastic threads have a two-way skip weave has been explained, but the elastic thread 1 in the +α° direction is in the -α° direction.
It may be a 1-way skipped structure in which one elastic thread 2 is alternately crossed in the direction, a 3-way skipped structure in which 3 threads are alternately crossed, or a 4-way skipped structure in which 4 yarns are alternately crossed. It is not limited.

In order for the reinforcing fiber yarn used in the present invention to exhibit its performance as a tubular body constituting fishing rods, golf shafts, tennis racket frames, bicycle frames, etc.,
It is preferable that the tensile modulus is 7,000 kg/mm2 or more and the tensile strength is 200 kg/mm2 or more. Examples include carbon fiber yarn, glass fiber yarn, polyaramid fiber yarn, and silicone carbide fiber yarn. Among these, carbon fiber yarns having a tensile modulus of 20,000 kg/mm 2 or more and a tensile strength of 200 kg/mm 2 or more are preferred because they can reduce the weight of the sports and leisure goods mentioned above. Further, the fineness of the reinforcing fiber yarn is 500 to 20,000 deniers, more preferably 1,500 to 10,000 deniers. Furthermore, the reinforcing fiber yarns constituting the braid of the present invention are not limited to one type; for example, in order to have damping properties as an FRP tubular body, carbon fiber yarns, polyaramid fiber yarns, carbon fiber yarns, etc. Yarn and vinylon fiber yarn can be used together.

[0014] The yarns arranged in the bias direction hold the reinforcing fiber yarns together, and when the braid is placed over the core material during molding, the braid is expanded and the core material is inserted, and then the braid is covered with the core material. It plays the role of contracting in the radial direction so that it fits tightly. Further, when the braid is located on the inner surface of the core material, the braid plays a role of extending in the radial direction so as to come into close contact with the inner surface of the core material. Furthermore, when it is placed along a ring-shaped object such as a tennis racket frame, it plays the role of shrinking or expanding so as to come into close contact with the ring-shaped core material. In the braid of the present invention, since elastic yarn is used for the threads in the bias direction, the braid can be easily contracted or expanded in the radial direction during molding, and the braid can be easily and accurately used as a core material. It can be brought into close contact with the

[0015] Such elastic yarns include false twisted yarns obtained by processing multifilament yarns and monofilament yarns made of thermoplastic resins such as nylon resin, polybutylene terephthalate resin, and polyester resin, that is, crimped yarns. can be mentioned. False twisted yarns are, for example,
First, nylon fiber yarn, polybutylene terephthalate fiber yarn, or polyester fiber yarn is strongly twisted at a rate of about 500 to 5,000 times/m, and the twist is heat-set at 160 to 240°C, then cooled to room temperature. It is obtained by untwisting the fibers approximately 0 times. Since the shape is fixed in the twisted state, when it is untwisted, a woolly-like curl appears. False-twisted yarn is in a crimped state when no tension is applied, and when tension is applied to it, it stretches by the length of the crimped yarn, but when no tension is applied, it returns to its original state. It has the property of shrinking. These properties of false twisted yarn are as follows: crimp ratio = [load (0.1
Length at initial load (0.02 g/denier) - length at initial load (0.02 g/denier) / [length at initial load (0.02 g/denier)] x 100 (%) Although,
The crimp ratio of the false twisted yarn used in the present invention is preferably 100% or more. If it is less than 100%, the radial elongation of the braid will decrease, making it difficult to insert it into the core material. Furthermore, after insertion into the core material, the amount of contraction or expansion in the radial direction decreases, resulting in poor adhesion to the core material.

[0016] In the above, an example in which the elastic yarn is a false twisted yarn has been described, but the elastic yarn may also be a polyurethane fiber yarn or a rubber yarn. Further, these elastic yarns may be coated with false twisted yarn as appropriate.

[0017] Since the elastic thread used in the present invention cannot essentially serve as a reinforcing material in the fiber-reinforced composite material, it is better to use a smaller amount. The fineness of the elastic yarn is preferably 50 to 500 deniers, more preferably 100 to 300 deniers. If it is less than 50 deniers, the shrinkage force in the radial direction will be small, and if it exceeds 500 deniers, the amount of elastic threads will increase, and the volume content of reinforcing fibers in the fiber reinforced composite material will become small.

The elongation in the radial direction of the braid of the present invention is 20% or more when the tubular round braid is folded so that a crease is formed in the length direction and a load of 100 g per 10 mm is applied in the radial direction of the braid. It is preferable. If it is less than 20%, the braid will have little elongation in the radial direction, making it difficult to insert it into the core material. Furthermore, after insertion into the core material, the amount of radial contraction decreases, resulting in poor adhesion to the core material.

In particular, when the elastic yarn is a false-twisted yarn, it is necessary that the false-twisted yarn is crimped when assembled into a braid. If the braided cord in which the false twisted yarn is stretched out is attempted to be expanded further, a large amount of force is required, resulting in extremely poor workability.

[0020] The above-mentioned braid can be manufactured as follows. FIG. 2 shows an example of the method for manufacturing the braid of the present invention. The reinforcing fiber yarns 3 are supplied radially from below the surface plate 4, and on the surface plate 4 there are elastic yarns 1 and 2 wound around bobbins.
is installed on the carrier 5 and moved around the reinforcing fiber thread 3 while being guided in a wavy trajectory, so that the reinforcing fiber thread 3 is inserted into the braid formed by the elastic threads 1 and 2.
By continuously winding this up with the winding device 6, the braid of the present invention can be obtained.

[0021] When the elastic yarn is a false-twisted yarn, the structure forming part (A) where the elastic yarns are interlaced with each other is placed inside or outside of the radial yarn sheet formed by the reinforcing fiber yarn and the false-twisted yarn. If you install a gauge 7 with a diameter larger than the diameter of the braid you want to obtain and braid the braid with a diameter larger than the diameter of the braid you want to obtain, it will be in a stretched state when it is in a no-tension state. The false-twisted yarn that was previously in the process is now in a crimped state.

[0022] Using the braid of the present invention, according to the present invention,
For example, an FRP tubular body can be manufactured as follows. The core is suitably made so that the braid of the present invention alone in which reinforcing fiber threads are arranged in the length direction of the braid, or the braid of the present invention and a tubular round braid in which reinforcing fiber threads are arranged only in the bias direction are alternately layered. Insert into material. The braid inserted into this core material is placed in the cavity formed by the male and female molds, and after sealing the male and female molds, a thermosetting resin such as epoxy resin, unsaturated polyester resin, or phenolic resin is filled into the cavity. The resin is injected and heated to harden the resin. Thereafter, by removing the core material if necessary, a tubular FRP can be obtained.

Furthermore, by using the braided cord of the present invention, when forming a tapered tubular body such as a fishing rod or golf shaft, the elastic threads stretch uniformly when the braided cord is expanded, so that they can be inserted into or covered with the core material. The reinforcing fiber yarns oriented in the length direction can be spaced at equal intervals in the circumferential direction, and all the reinforcing fiber yarns can be oriented in the ridgeline direction of the tubular body, making it possible to fully demonstrate the performance of the reinforcing fibers. can.

[0024]

Effects of the Invention As explained above, in the present invention, in a three-axis circular braid consisting of threads in the length direction and in a bias direction of ±α° with respect to the length direction, the threads in the length direction is a reinforcing fiber yarn, and the yarn in the bias direction of ±α° is an elastic yarn, so it is possible to orient the fibers in the ridgeline direction of the tubular body without wraps, making it possible to create a tubular fiber reinforced yarn with excellent physical properties. A composite material is obtained. In addition, even if the braid is inserted into the core material during molding, the braid can be naturally and well adhered to the core material after insertion, which not only improves workability but also prevents the reinforcing fibers from being arranged in disorder, resulting in a uniform A tubular fiber-reinforced composite material is obtained.

Furthermore, when a crimped yarn is used as the elastic yarn, since the crimped yarn is braided with the reinforcing fiber yarn in a crimped state, the reinforcing fiber yarn in the length direction of the braid is not crimped. The shrinkage of the threads results in a braid that is so densely arranged that the threads come into contact with each other, yielding a tubular fiber-reinforced composite material with a high fiber volume content.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged plan view of a triaxial circular braid of the present invention.

FIG. 2 is a side view showing an example of the method for manufacturing the braided cord of the present invention.

[Explanation of symbols]

1, 2 Elastic yarn (yarn in bias direction) 3, 3a, 3
b Reinforcement fiber yarn (longitudinal yarn) 4 Surface plate 5 Carrier 6 Winding device 7 Gauge

Claims (4)

[Claims] [Claim 1] Length direction and ±α with respect to the length direction
A reinforcing braid characterized in that the threads in the longitudinal direction are made of reinforcing fiber yarns, and the threads in the bias direction of ±α° are made of elastic yarns in a triaxial circular braid made of threads in a bias direction of °. . 2. The reinforcing braid according to claim 1, wherein the elastic yarn is a crimped yarn, and the crimped yarn is braided with reinforcing fiber yarn in a crimped state. 3. The reinforcing braid according to claim 1, wherein said elastic thread is made of polyurethane fiber. 4. A tubular fiber-reinforced composite material comprising the reinforcing braid according to any one of claims 1 to 3.