JPH10235767A - Carbon fiber reinforced plastic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the impact resistance of carbon fiber reinforced plastic with its good properties maintained by arranging a protective layer on the surface of a backing which is made of the reinforced plastic and whose tensile elongation at break is specified. SOLUTION: A carbon fiber reinforced plastic member has a backing made of carbon fiber reinforced plastic and a protective layer arranged on the surface of the backing. The tensile elongation at break at least in one direction of the reinforced plastic is more than 1.3%. An epoxy resin is used preferably as the matrix resin of the backing, and the protective layer preferably consists substantially of an organic polymer or glass fiber reinforced plastic. The organic polymer means polyester, aramide, polyimide, poly(ether ether ketone), etc. The thickness of the protective layer is preferably 1/5 or less, more preferably 1/10 or less. of that of the backing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member made of carbon fiber reinforced plastic, and particularly to a member having excellent impact resistance and having a golf club shaft, a ski pole, other sports equipment, a pressure vessel, and an aircraft structure. TECHNICAL FIELD The present invention relates to a member made of carbon fiber reinforced plastic suitable for being used for materials, other industrial structural materials, and the like.

[0002]

2. Description of the Related Art Carbon fiber reinforced plastic members having excellent properties such as light weight, high strength and high elasticity are widely used as sports equipment and industrial structural materials.

[0003] By using carbon fiber reinforced plastic, the weight of the member can be reduced as compared with conventional materials. However, the impact resistance of carbon fiber reinforced plastics cannot be said to be sufficiently high compared to their static strength and high elastic modulus, and depending on the application, weight reduction of members is limited by the impact resistance. .

For example, in a golf club shaft, a tree branch, a wall surface, or the like directly hits the shaft depending on a use condition, and the shaft may be broken by an impact force. Further, the ski pole may be damaged by the impact of the edge of the ski during the run, for example, due to impact force. Pressure vessels, such as gas cylinders, may receive impact forces due to drops when handling the vessels, and impact damage remains in aircraft structural materials due to tool drops during the process.
It may cause a decrease in strength. Thus, it has been desired to improve the impact resistance of carbon fiber reinforced plastic members in many applications.

As a means for improving the impact resistance, a method of increasing the toughness of a matrix resin is described in Japanese Patent Application Laid-Open No. 60-47104, etc., but the effect of improving the impact resistance by this method is not sufficient. is not. In addition, physical properties and fatigue properties at high temperatures may be reduced, and the use of a resin different from the conventional one often requires changes in the manufacturing process and molding equipment, resulting in higher product costs and higher product quality. In many cases.

Japanese Patent Application Laid-Open Nos. 3-168167 and 3-168168 disclose that a golf club shaft made of carbon fiber reinforced plastic has an innermost layer and / or an innermost layer and an outermost layer made of an organic polymer. A method of disposing a film is described. However, these methods do not sufficiently improve the impact resistance, and further improvement is desired. It is possible to improve the impact resistance to some extent by increasing the thickness of the film, but in this case, the weight of the entire member increases, so the excellent properties of carbon fiber reinforced plastic such as light weight, high strength, and high elasticity are sufficient. Will not be alive.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art, and to use a carbon fiber reinforced plastic as a base material while maintaining excellent properties thereof while providing an unprecedentedly high impact resistance. Another object of the present invention is to provide a carbon fiber reinforced plastic member having the following.

[0008]

The present invention has the following configuration to achieve the above object.

That is, a carbon having a base material made of carbon fiber reinforced plastic and a protective layer disposed on the surface thereof, wherein the base material has a tensile elongation at break of more than 1.3%. It is a fiber reinforced plastic member.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A member made of carbon fiber reinforced plastic according to the present invention (hereinafter sometimes simply referred to as a member) has a base material made of carbon fiber reinforced plastic and a protective layer disposed on the surface thereof. The carbon fiber reinforced plastic constituting the base material has a tensile elongation at break of more than 1.3% in at least one direction.

In general, when an impact force is applied to a member from the outside, a large surface pressure is locally generated at the point of impact, while
A compression and tensile force is generated inside the member due to the deformation. The compressive force inside the member is usually highest near the point of impact. Many of the carbon fiber reinforced plastics have a lower compressive strength than a tensile strength, and fracture starts by a compressive force near an impact point, which often propagates to the entire member. Therefore, in order to enhance the impact resistance of the carbon fiber reinforced plastic member, it has been effective to mainly increase the compressive strength of the carbon fiber reinforced plastic.

However, according to the findings of the present inventor, when a protective layer is provided on the surface (including the impact point) of such a carbon fiber reinforced plastic member, the surface pressure at the impact point and the pressure near the impact point can be reduced. The compression force is alleviated, the impact resistance is improved, and the tensile force in the member triggers the member to break. Therefore, the tensile properties are more dominant in impact resistance than previously thought. Therefore, in the member of the present invention, the tensile elongation at break of the substrate is 1.
By setting it to more than 3%, preferably more than 1.5%, a high impact resistance which cannot be considered conventionally is exhibited.

The tensile elongation at break of the substrate does not necessarily need to be high in all directions of the substrate, but may be more than 1.3% in at least one direction. This direction preferably corresponds to the direction of the external force applied to the member. That is, for example, in the case of a member that receives a bending impact load as an external force, the tensile elongation at break of the base material preferably exceeds 1.3% in the direction in which tensile force is applied by bending deformation.

The tensile elongation at break of the substrate can be measured according to JIS K 7073, after removing the protective material from the member, attaching a strain gauge. JIS K such as cylindrical
In the case of a member from which a test piece compliant with 7073 cannot be obtained, the tensile elongation at break can be measured by applying a strain gauge to the substrate and uniformly applying a tensile load until fracture. Here, the term “fracture” means that the base material is divided and the load-bearing ability is lost.

The reinforcing fibers of the base material may be carbon fibers irrespective of pitch type or PAN type. To increase the tensile elongation at break of the base material, the elongation of the reinforcing fibers must be 1.5%. Preferably, it is more than 2.0%.

As the matrix resin of the base material, various thermosetting resins and thermoplastic resins such as an epoxy resin, a phenol resin, a polyester resin and a vinyl ester resin can be used. Among them, an epoxy resin which is easy to mold and has excellent physical properties is preferable. In addition, in order to add various functions and performances, the matrix resin may contain a substance such as particles or fibrous materials as long as the effects of the present invention are not impaired.

The effect of improving the impact resistance in the present invention is greater when the tensile strength is higher than the static bending strength of the substrate. In the case of a member without a protective layer, it takes a mode in which it breaks due to surface pressure at the impact point or a compressive force in the vicinity thereof, that is, a fracture mode close to bending, whereas if a protective layer is present, it breaks in a tensile mode. Therefore, as a result, the effect of the protective layer increases as the ratio of the tensile strength to the bending strength increases. Specifically, the tensile strength of the base material preferably exceeds 1.2 times the bending strength.
More preferably, it exceeds 5 times. The bending strength is determined in the same manner as in the tensile strength, after removing the protective material, according to JIS K7074.
Can be measured according to

Preferably, the protective layer is substantially made of an organic polymer or glass fiber reinforced plastic. Substantially means that other substances may be contained as long as the effects of the present invention are not impaired. The organic polymer is, for example, polyester, aramid, polyimide, polyetheretherketone, or the like. The glass fiber reinforced plastic is a material in which so-called S glass, E glass or the like is used as a reinforcing fiber, and an epoxy resin, a phenol resin or the like is used as a matrix resin. The protective layer may be integrally formed at the same time as the formation of the base material, or may be integrated with the base material by various methods, such as bonding the base material with an adhesive after forming the base material.

The member of the present invention has an energy absorption in a Charpy impact test according to JIS K 7077,
It is preferably more than 1.5 times that of the base material alone. Thereby, a sufficiently high impact resistance improving effect can be obtained in practical use. The Charpy impact test was conducted according to JIS K
Irrespective of the definition of 7077, the test is performed with the distance between the test-piece supporting tables within the range of 25 to 30 times the thickness of the test piece.

The form of the reinforcing fiber of the base material can be appropriately selected depending on the use of the member and the manner in which a load is applied. It may be a continuous fiber that is aligned, may have a woven structure, or may be a combination thereof, but is a continuous fiber that is aligned to increase the tensile strength. Is preferred. The alignment direction may be one direction, or may be two or more different directions.

If the content of the reinforcing fibers in the substrate is too high, problems such as generation of voids during molding tend to occur, and if it is too low, the tensile strength of the substrate tends to decrease.
It is preferably in the range of 30 to 85% by volume, and 50 to
More preferably it is in the range of 75% by volume, most preferably around 60% by volume.

The protective layer absorbs external impact and efficiently reduces local and compressive forces generated on the substrate.
It is preferable to have sufficient tensile strength. Specifically, it is preferable that the tensile strength in at least one direction exceeds 200 MPa. Further, for the same reason, the thickness of the protective layer preferably exceeds 100 μm.

The ratio of the thickness of the protective layer to the thickness of the substrate is preferably such that the protective layer does not exceed 1/5 of the thickness of the substrate,
More preferably, it does not exceed 10. If the thickness of the protective layer is larger than this range, the effect of increasing the weight of the entire member will increase.

It is preferable that the thickness of the entire member does not exceed 20 mm. If it exceeds 20 mm, the effect of improving the impact resistance by the protective layer tends to decrease.

The member of the present invention has excellent characteristics of carbon fiber reinforced plastic such as light weight, high strength and high elasticity, and high impact resistance, and is a member which receives an external impact such as a hit, such as a shaft for a golf club or a ski. Pole,
It can be suitably used as fishing rods and other sports equipment, pressure vessels, aircraft structural materials, marine structural materials and other industrial structural materials.

[0026]

【Example】

Example 1 PAN-based carbon fiber (elongation 2.1%, tensile strength 4900M)
Unidirectional prepreg A made of epoxy resin and a tensile modulus of 230 GPa (Pa, prepreg weight 224 g / m)
² , the fiber content was 67% by weight) and the fiber direction was
14), and cured by a predetermined method to produce a substrate molded plate.

The thickness of the formed plate was 2.1 mm. A tensile test piece was cut out from this molded plate in accordance with JIS K 7073 with the 0-degree direction as a longitudinal direction, and the tensile test piece was measured. As a result, the tensile strength was 2550 MPa and the tensile elongation at break was 1.7%. Further, a bending test piece was cut out from this molded plate in accordance with JIS K 7074 with the 0 degree direction as a longitudinal direction and measured, and as a result, the bending strength was 1670 MPa. (Tensile strength / Bending strength = 1.53)
The Charpy impact test piece was cut out and measured according to K 7077 with the 0 degree direction as the longitudinal direction, and as a result, the absorbed energy was 1.8 J.

Next, a polyester film (thickness 125 μm, tensile strength 210 MPa) was formed on one side of the molded plate as a protective layer.
a) was bonded with a cyanoacrylate adhesive to produce a member.

From this member, a Charpy impact test piece was prepared in accordance with JIS K 7077 with the 0 ° direction as the longitudinal direction, and the measurement was performed such that the hammer hit the side with the protective layer. The distance between the test piece supports was 60 mm.

As a result of the measurement, the absorbed energy was 3.2 J.

Example 2 A base plate was prepared in the same manner as in Example 1, and a glass fiber reinforced plastic (plain weave E glass fiber / epoxy resin, fiber volume content 40%, molding thickness 320 μm) was used as a protective layer.
m, and a tensile strength of 250 MPa), except that a member was produced in the same manner as in Example 1.

When the Charpy impact absorption energy of this member was measured in the same manner as in Example 1, it was 3.5 J.

Example 3 In preparing a molded plate for a base material, the prepreg A was placed in the direction [0/90 /
0/90/0/90/0/0/90/0/90/0/9
[0/0], except that they were laminated in the order of [0/0], to produce a molded substrate plate in the same manner as in Example 1.

The thickness of the formed plate was 2.1 mm. When the respective properties were measured in the same manner as in Example 1, the tensile strength was 13
50 MPa, tensile elongation at break of 1.6%, flexural strength of 88
0MPa and Charpy impact absorption energy were 1.0J.

Next, a member was produced by bonding a protective layer in the same manner as in Example 1.

The Charpy impact absorption energy of this member was measured in the same manner as in Example 1, and it was 1.6 J.

Example 4 A PAN-based carbon fiber (elongation: 1.0%, tensile strength: 422) was wound around a release-treated tapered stainless steel core.
0 MPa, tensile modulus 436 GPa) and unidirectional prepreg B (prepreg weight 224 g) made of epoxy resin
/ M ² , a fiber content of 67% by weight) is wound so that the fiber direction forms an angle of 45 ° with the mandrel main shaft, and the unidirectional prepreg A used in Example 1 is wound therearound. And then 30
A polyester film similar to that used in Example 1 is wound around the portion up to 0 mm for one round, and then wrapping tape is wound, cured, and the tape is removed in the same manner as in forming a general carbon shaft. Shaft was obtained. In addition, outer periphery polishing and coating after molding were not performed. When the thickness of the carbon fiber reinforced plastic layer was measured from the shaft end face, it was 1.3 mm. In this manner, two golf club shafts were produced.

When a strain gauge was attached to one of the shafts at a position 90 mm from the tip of the small diameter side and a tensile load was applied to the entire shaft, the tensile elongation at break was 1.8%.

Another 40-140 mm portion of the other shaft was cut out from the tip of the small-diameter portion, and the Charpy impact test was performed by setting the distance between supports to 60 mm.
The absorbed energy was 13.5J.

Example 5 A prepreg A was wound around a release-treated tapered stainless steel core so that the fiber direction was perpendicular to the core shaft, and prepreg A was further wound around the prepreg A and the fiber direction was Wound so as to coincide with the main axis, and then wound around the portion from the tip of the small diameter side to 300 mm for one round of the same polyester film as used in Example 1, and then in the same manner as in Example 4, A ski pole shaft was obtained. The thickness of the carbon fiber reinforced plastic layer measured from the end face of the shaft was 1.5 mm. In this manner, two ski pole shafts were produced.

When a strain gauge was attached to a portion of one of the shafts, 150 mm from the tip of the small diameter side, and a tensile load was applied to the entire shaft, the tensile elongation at break was 1.7%.

Another portion of this shaft was cut out from the tip of the small diameter portion to 300 mm, and 15 mm from the tip.
4J at 0mm part by DuPont type coating film impact tester
Made a shock. Next, a four-point bending test was performed so that the impacted portion received the maximum compressive force. At this time, the distance between the indenters was 60 mm, and the distance between the fulcrums was 200 mm.
As a result, the breaking load was 3.1 kN.

Comparative Example 1 Instead of prepreg A, PAN-based carbon fiber (elongation: 1.
5%, tensile strength 3530MPa, tensile modulus 230GP
a) Unidirectional prepreg C composed of a) and an epoxy resin (prepreg weight 224 g / m ² , fiber content 67% by weight)
A molded plate for a base material was produced in the same manner as in Example 1 except for using.

The thickness of the formed plate was 2.1 mm. When the respective properties were measured in the same manner as in Example 1, the tensile strength was 18
00MPa, tensile elongation at break 1.2%, flexural strength 16
50 MPa (tensile strength / flexural strength = 1.09), and Charpy impact absorption energy was 0.9 J.

Next, a protective layer was adhered in the same manner as in Example 1 to produce a member.

When the Charpy impact absorption energy of this member was measured in the same manner as in Example 1, it was 1.1 J.

Comparative Example 2 A molded plate for a base material similar to that of Comparative Example 1 was prepared, and a glass fiber reinforced plastic (plain woven E glass fiber / epoxy resin, fiber volume content 40%, molded thickness 320 μm) was used as a protective layer.
A member was produced in the same manner as in Comparative Example 1, except that m) was used.

When the Charpy impact absorption energy of this member was measured in the same manner as in Example 1, it was 1.2 J.

Comparative Example 3 Two shafts for a golf club were produced in the same manner as in Example 4 except that prepreg C was used instead of prepreg A.

When a strain gauge was attached to a portion of one of the shafts 90 mm from the tip end on the small diameter side and a tensile load was applied to the entire shaft, the tensile elongation at break was 1.0%.

Another 40-140 mm portion of this shaft was cut out from the tip of the small-diameter portion, and the Charpy impact test was performed by setting the distance between the supports to 60 mm.
The absorbed energy was 8.9J.

Comparative Example 4 Two ski pole shafts were produced in the same manner as in Example 5 except that prepreg C was used instead of prepreg A.

When a tensile load was applied to one of the shafts in the same manner as in Example 5, the tensile elongation at break was 1.1%.

An impact was applied to another of the shafts in the same manner as in Example 5, and a four-point bending test was performed. As a result, the breaking load was 1.6 kN.

[0055]

The member of the present invention has a tensile elongation at break of 1.3.
% Of a carbon fiber reinforced plastic substrate,
By having a protective layer arranged on its surface, it is lightweight,
It has unprecedentedly high impact resistance, while hardly impairing the excellent properties of carbon fiber reinforced plastic such as high strength and high elasticity.

Since the tubular body of the present invention has high impact resistance, it is particularly suitably used for golf club shafts, ski poles and other sports equipment, pressure vessels, aircraft structural materials and other industrial structural materials. Can be

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B32B 5/00 B32B 17/04 Z 7/02 101 B29C 67/14 X 17/04 P

Claims (18)

[Claims] 1. A carbon material comprising a substrate made of carbon fiber reinforced plastic and a protective layer disposed on the surface thereof, wherein the substrate has a tensile elongation at break of more than 1.3%. Fiber reinforced plastic members. 2. The tensile strength of a substrate is 1.2 times its bending strength.
The carbon fiber reinforced plastic member according to claim 1, wherein the number is more than twice. 3. The member made of carbon fiber reinforced plastic according to claim 1, wherein the protective layer is substantially made of an organic polymer. 4. The member made of carbon fiber reinforced plastic according to claim 1, wherein the protective layer is substantially made of glass fiber reinforced plastic. 5. The carbon fiber reinforced plastic member according to claim 1, wherein the Charpy impact absorption energy exceeds 1.5 times the Charpy impact absorption energy of the base material alone. 6. The carbon fiber reinforced plastic member according to claim 1, wherein the reinforcing fibers of the base material are continuous fibers that are aligned. 7. The member made of carbon fiber reinforced plastic according to claim 6, wherein the alignment direction of the reinforcing fibers is substantially one direction. 8. The member according to claim 6, wherein the reinforcing fibers are aligned in two or more different directions. 9. The carbon fiber reinforced plastic member according to claim 1, wherein the protective layer has a tensile strength exceeding 200 MPa. 10. The carbon fiber reinforced plastic member according to claim 1, wherein the thickness of the protective layer exceeds 100 μm. 11. The carbon fiber reinforced plastic member according to claim 1, wherein the thickness of the protective layer does not exceed 1/5 of the thickness of the base material. 12. A member made of carbon fiber reinforced plastic according to claim 1, wherein the total thickness does not exceed 20 mm. 13. A golf club shaft comprising the carbon fiber reinforced plastic member according to claim 1. 14. A ski pole comprising the carbon fiber reinforced plastic member according to claim 1. 15. A fishing rod comprising the carbon fiber reinforced plastic member according to claim 1. 16. A pressure vessel comprising the carbon fiber reinforced plastic member according to claim 1. 17. An aircraft structural material comprising the carbon fiber reinforced plastic member according to any one of claims 1 to 12. 18. A structural material for ships, comprising the member made of carbon fiber reinforced plastic according to any one of claims 1 to 12.