JP2515688B2 - Hybrid FRP laminate - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a hybrid FR made of carbon fiber prepreg and glass fiber prepreg.
It relates to a P laminate.

[0002]

2. Description of the Related Art In sports and leisure products such as skis, tennis racket frames, golf club shafts, and bows, FRP laminates using prepreg are used.

The prepreg consists of reinforcing fibers impregnated with a resin, but an epoxy resin or an unsaturated polyester resin is often used as the resin component, and the reinforcing fibers are unidirectional carbon fibers or glass. Fiber may be used.

A hybrid prepreg in which fibers such as boron fibers, metal fibers, organic fibers, glass fibers and inorganic fibers are arranged in the same direction in carbon fibers arranged in one direction as reinforcing fibers is disclosed in Japanese Patent Laid-Open No. 202322/1993. Japanese Patent Laid-Open No. 3-202323, Japanese Patent Laid-Open No. 3-20
It is disclosed in Japanese Patent No. 2324, Japanese Patent Application Laid-Open No. 3-221414, Japanese Patent Application Laid-Open No. 3-221413, and Japanese Patent Application Laid-Open No. 3-221414.

[0005]

Since the FRP laminate is lightweight and has excellent mechanical properties, it has been applied to various fields such as sports / leisure products. Among them, a hybrid FRP laminate in which two or more kinds of mechanically different reinforcing fibers are combined is expected to enable a design having an excellent function that cannot be obtained by an FRP laminate using a single reinforcing fiber. It

However, in the hybrid laminated plate, since the elastic constants of the reinforcing fibers used are different, it is difficult to cause stress discontinuity between the layers. Therefore, what kind of design leads to improvement in function? The current situation is unclear.

Under such circumstances, the present invention provides a highly functional hybrid FRP laminate made of a carbon fiber prepreg having a unidirectional fiber direction and a glass fiber prepreg having a unidirectional fiber direction. That is the purpose.

[0008]

Hybrid F of the present invention
The RP laminate has one fiber direction and n layers (
Dashi n is an integer of 20 or more) Carbon fiber prepreg
(C) , the fiber direction is one direction and the number of layers is m (however, m
The glass fiber prepreg (G) is an integer) of 1 to n / 4
However , a state in which the fiber directions of the respective layers are the same and the m-layer glass fiber prepreg (G) is laminated so as to be sandwiched in a substantially central portion of the n-layer carbon fiber prepreg (C). Therefore, it has a structure integrated with heating.

The present invention will be described in detail below.

In the present invention, a carbon fiber prepreg (C) having a unidirectional fiber direction and a glass fiber prepreg (G) having a unidirectional fiber direction are used.

In this case, the fiber diameter of the glass fiber prepreg (G) is larger than that of the carbon fiber prepreg (C), more specifically, the glass fiber prepreg (G).
It is desirable to set the conditions such that the fiber diameter of the carbon fiber prepreg (C) is 2 times or more, preferably 2.5 times or more the fiber diameter of the carbon fiber prepreg (C).

The above-mentioned carbon fiber prepreg (C) and glass fiber prepreg (G) are prepared by aligning reinforcing fibers (carbon fiber, glass fiber) in one direction, and then applying a wet method (solvent type) or a dry method (hot melt). Type) to impregnate a mixture of a resin and a curing agent, and then dry (in the wet method) or cool (in the dry method). Volume content V of fiber component in prepreg
f is often set to about 40 to 70%.

As the resin component, epoxy resin, unsaturated polyester resin, phenol resin, diallyl phthalate resin, vinyl ester resin, silicone resin, polyimide or the like is used.

Among these resins, bisphenol A
-Epoxy resins such as diglycidyl ether type epoxy resin and novolac resin-glycidyl ether type epoxy resin are particularly important. As the curing agent when using the epoxy resin, organic acid anhydride-based or amine-based curing agents are used.

And, in the present invention, the above fiber direction
Is in one direction and the number of layers is n (where n is an integer of 20 or more.
Number) Whether the fiber direction is one direction with the carbon fiber prepreg (C)
The number of layers is m (where m is an integer of 1 to n / 4 ) and the minority of the glass fiber prepreg (G), so that the fiber directions of the layers are the same and the n layers of carbon fiber prepreg are the same.
The glass fiber prepreg of the above-mentioned m-layer is provided almost in the center of (C).
(G) is laminated so that it sandwiches.

Thus, the n-layer carbon fiber prepreg (C)
By interposing m layers of the glass fiber prepreg (G) in the substantially central portion of the above , particularly preferable results are obtained in that only the interlaminar shear strength is improved without lowering the bending rigidity of the laminate.

When the first purpose is to improve the interlaminar shear strength, the number of layers m of the glass fiber prepreg (G) to be interposed is:
The smaller the range is from 1 to n / 4, the more advantageous it is. On the other hand, if cost is important, there will be
The number of layers m of the fiber prepreg (G) is in the range of 1 to n / 4
The larger the number, the more advantageous.

When the m- layer glass fiber prepreg (G) is interposed in the substantially central portion of the n- layer carbon fiber prepreg (C) and the layers are laminated in the same fiber direction, Is shaped into a desired shape such as a flat plate shape, a curved plate shape, a tubular shape, or a tubular shape, and then integrated by heating. The curing temperature at this time varies greatly depending on the type of resin component, but is about 120 to 230 ° C (about 120 to 160 ° C when using normal grade resin, about 170 to 230 ° C when using heat resistant grade resin). Often set to. As a result, the target hybrid FR
A P laminate is obtained.

The hybrid FRP laminate of the present invention thus obtained is used for skis, tennis racket frames, golf club shafts, bows / waws, fishing rods, baseball bats, marine sports (yoto, motor boats, sailboards, surfboards). Etc.), pole fly pole, baton,
It is particularly useful in the sports and leisure fields including playground equipment (pools, slides, etc.), and can also be used in aircraft / space-related materials, automobile parts, electronic / electric parts, general industrial applications, and the like.

[0020]

Function: The fiber is unidirectional and the number of layers is n (however, n
Is an integer of 20 or more) , a carbon fiber prepreg (C) ,
The fiber direction is unidirectional and the number of layers is m (where m is 1 to n /
Glass fiber prepreg (G) , which is an integer of 4) , and m layers of glass fiber prepreg (G) are provided at approximately the center of the n layers of carbon fiber prepreg (C) so that the fiber directions of the layers are the same. When heat-integrated in a state of being laminated so as to interpose in a sandwich shape, when a bending stress is applied, the delamination point becomes different depending on the number of intermediate heterogeneous fiber layers. When the intermediate dissimilar fiber layer is a glass fiber layer, the interlaminar shear strength is improved when the number of layers is equal to or less than a certain number.

Further, when the fiber diameter of the glass fiber prepreg (G) interposed in the middle is made larger than the fiber diameter of the carbon fiber prepreg (C), the carbon fiber / glass fiber layer in the obtained hybrid FRP laminate is separated. Carbon fibers having a small fiber diameter enter the gaps between the fibers of the glass fiber layer having a large fiber diameter, and delamination is unlikely to occur even though stress discontinuity occurs between the layers.

[0022]

EXAMPLES The present invention will be further described with reference to examples. Note that Vf is the volume content of the fiber component in the prepreg, as described above.

<Preparation of test piece> Thickness: 0.122 mm, Vf = 5
Unidirectional carbon fiber / epoxy resin prepreg (C) with 6%, fiber diameter 7 μm, and unidirectional glass fiber / epoxy resin prepreg with thickness 0.122 mm, Vf = 46%, fiber diameter 19 μm
Using two types of prepregs (G) and (Tonen Co., Ltd.), 100 mm × 200 mm × 4.5 mm flat plates each having a laminated structure of 37 layers were formed by the vacuum bag method as follows. Then, a strip-shaped test piece having a size of 30 mm (fiber direction) × 6 mm (direction perpendicular to the fiber direction) was cut out from this flat plate.

<Lamination Structure> C type • C ₃₇ (C) 37 layers unidirectional lamination body • C ₁₈ G ₁ C ₁₈ (C) 18 layers / (G) 1 layer / (C) 18 layers unidirectional lamination Body ・ C ₁₇ G ₃ C ₁₇ (C) 17 layers / (G) 3 layers / (C) 17 layers Unidirectional stack ・ C ₁₄ G ₉ C ₁₄ (C) 14 layers / (G) 9 layers / ( C) 14-layer unidirectional laminate G type-G ₃₇ (G) 37-layer unidirectional laminate-G ₁₈ C ₁ G ₁₈ (G) 18-layer / (C) 1-layer / (G) 18-layer Directional stack ・ G ₁₇ C ₃ G ₁₇ (G) 17 layers / (C) 3 layers / (G) 17 layers Unidirectional stack ・ G ₁₄ C ₉ G ₁₄ (G) 14 layers / (C) 9 layers / (G) 14 layer unidirectional laminate

<Test Method> For each of the above test pieces, an Instron 4206 universal tester was used, and the span distance was 20.
The maximum load p _max was obtained by the three-point bending short beam method under the conditions of mm and crosshead speed of 1 mm / min, and this was substituted into the following formula to obtain the apparent interlayer shear strength τ _max . In the following formula, b is the width of the test piece and h is the thickness of the test piece. τ _max = 3p _max / 4bh

<Results> FIG. 1 shows the relationship between the apparent interlaminar shear strength τ _max and the laminated layer of the interstitial dissimilar prepregs when a predetermined number of dissimilar prepregs are interposed in the C type and G type. Table 1 shows the average value of the apparent interlayer shear strength τ _max at that time.

[0027]

[Table 1] Laminate composition τ _max Average value C type C ₃₇ 8.977 mPa (100.0%) C ₁₈ G ₁ C ₁₈ 9.567 mPa (106.6%) C ₁₇ G ₃ C ₁₇ 9.174 mPa (102.2%) C ₁₄ G ₉ C ₁₄ 8.745 mPa (97.4 %) G type G ₃₇ 7.602 mPa (100.0%) G ₁₈ C ₁ G ₁₈ 7.596 mPa (99.9%) G ₁₇ C ₃ G ₁₇ 7.551 mPa (99.3%) G ₁₄ C ₉ G ₁₄ 7.895 mPa (103.4%)

<Analysis> From FIG. 1 and Table 1, in the G type, when one or three layers of carbon fiber prepreg (C) are interposed between the multiple layers of glass fiber prepreg (G), the glass fiber It can be seen that τ _max is almost the same as that of the FRP laminate having only prepreg (G), but τ _max is slightly improved by interposing 9 layers of carbon fiber prepreg (C) in the middle.

On the other hand, in the C type, the glass fiber prepreg is provided in the middle of the carbon fiber prepreg (C) having many layers.
Carbon fiber prepreg (C) when one layer of (G) is interposed
Τ _max increased by 6 to 7% compared to the FRP laminate of
Even when three layers of carbon fiber prepreg (C) are interposed in the middle, τ is smaller than that of an FRP laminate having only carbon fiber prepreg (C).
_{When max} is increased and 9 layers of carbon fiber prepreg (C) are interposed in the middle, only F of carbon fiber prepreg (C) is used.
It can be seen that τ _max becomes slightly inferior to the RP laminate.

In the observation of the cross-sectional photograph of each test piece after fracture,
C ₃₇ which is an FRP laminate consisting of only carbon fiber prepreg (C)
In Fig. ₁ , delamination occurs at several points on the cross section, whereas in C ₁₈ G ₁ C ₁₈ , the neutral axis changed to the glass fiber prepreg (G) layer is avoided, and delamination occurs only at one point in the vicinity. It turned out that C ₁₇ G ₃ C ₁₇ and C ₁₄ G ₉ C ₁₄
In, the peeling occurred in both the glass fiber prepreg (G) layer and the carbon fiber prepreg (C) layer.

FR of glass fiber prepreg (G) only
In G ₃₇ which is a P laminated body, peeling near the neutral axis, G
_{For 18} C ₁ G ₁₈ , peeling of the glass fiber prepreg (G) layer, G
_{For 17} C ₃ G ₁₇ , peeling in both the glass fiber prepreg (G) layer and the carbon fiber prepreg (C) layer, G ₁₄ C ₉ G
_In No. ₁₄ , peeling occurred only in the carbon fiber prepreg (C) layer. From this, it is understood that the peeling position changes due to the lamination of the intermediate different layers.

In both of the C type and G type, microscopic observation revealed that discontinuity of stress occurred between the layers of carbon fiber layer / glass fiber layer in all the layer constitutions, even though the discontinuity was generated between the layers. It was found that no peeling occurred.

FIG. 2 is a sectional view between the carbon fiber / glass fiber layers in the case of C ₁₈ G ₁ C ₁₈ , where (1) is the carbon fiber layer and (2) is
Is a glass fiber layer. The fiber diameters of the reinforcing fibers used in the examples are 7 μm in the case of carbon fiber prepreg and 19 μm in the case of glass fiber prepreg, and when they are laminated at the same orientation angle, carbon fibers enter into the gaps between the glass fibers. I understand. Therefore, Vf becomes high between these layers and is locally reinforced, so that peeling occurs in all the laminated structures while avoiding the carbon fiber / glass fiber layer.

In C ₁₈ G ₁ C ₁₈ , since the vicinity of the neutral axis having the highest interlaminar shear stress is locally strengthened by the penetration of the glass fiber layer and breaks at one carbon fiber layer near the neutral axis, C ₃₇ It is considered that τ _max is improved rather than that. However, in the C ₁₇ G ₃ C ₁₇ and C ₁₄ G ₉ C _14, since the thickness of the glass fiber layer in the vicinity of the neutral axis increases, and peeling occurred in the low interlaminar shear strength glass fiber layers, C ₁₈ Τ _max is lower than that of G ₁ C ₁₈ .

Similarly, in the G type, when the number of laminated intermediate different layers is 3 and 9, delamination is observed in the carbon fiber layer. However, unlike the C type fracture mode, even if one or three carbon fiber layers are used, a large number of delaminations occur in the glass fiber layer, so τ _max is not improved. However, since a release of carbon fiber layers in the G ₁₄ C ₉ G ₁₄ only, the improvement of tau _max is observed.

In both C type and G type, the delamination morphology differs depending on the number of laminated intermediate different layers, and the type of intermediate different layers and the number of laminated layers have a great influence on the apparent interlayer shear strength τ _max .

<Summary> From the above, it is understood that there is the following relationship between the laminated structure of the FRP laminate by the unidirectional sandwich of the carbon fiber prepreg / glass fiber prepreg and the apparent interlayer shear strength τ _max .・ Depending on the type of intermediate heterogeneous layer and the number of laminated layers, the delamination point becomes different, and the apparent interlaminar shear strength τ
affect _max . -When two types of prepregs having different fiber diameters are laminated at the same orientation angle, fibers having a small fiber diameter enter the gaps between the fibers having a large fiber diameter, and the layers are reinforced.

[0038]

According to the present invention, the number of layers is n.
The glass fiber prepreg (G) having m layers (where m is an integer from 1 to n / 4 ) is sandwiched in a substantially sandwiching manner in the central part of the carbon fiber prepreg (C) of 20 or more). By laminating and paying attention to the relationship between the fiber diameters of both reinforcing fibers, the purpose of improving the interlaminar shear strength can be achieved, or the cost can be reduced while maintaining the interlaminar shear strength.

[Brief description of drawings]

FIG. 1 is an apparent interlaminar shear strength τ _max when a predetermined number of different types of prepregs are interposed in C type and G type.
6 is a graph showing the relationship between the laminated layer of intervening different prepreg.

FIG. 2 is a sectional view between carbon fiber / glass fiber layers in the case of C ₁₈ G ₁ C ₁₈ .

[Explanation of symbols]

 (1)… Carbon fiber layer (2)… Glass fiber layer

Claims (3)

(57) [Claims] 1. The fiber direction is unidirectional and the number of layers is n (only
Where n is an integer of 20 or more) carbon fiber prepreg (C)
And the fiber direction is one direction and the number of layers is m (where m is 1
Glass fiber prepreg (G) , which is an integer of ~ n / 4 ),
In a state where the fiber directions of the respective layers are the same and the m-layer glass fiber prepregs (G) are laminated so as to be sandwiched in a substantially central portion of the n-layer carbon fiber prepregs (C), A hybrid FRP laminate having a structure integrated by heating. 2. The fiber diameter of the glass fiber prepreg (G) is larger than the fiber diameter of the carbon fiber prepreg (C).
The hybrid FRP laminate described. 3. The fiber diameter of the glass fiber prepreg (G) is at least twice the fiber diameter of the carbon fiber prepreg (C).
2. The hybrid FRP laminate according to item 2 .