JP2011195615A - Fiber-reinforced plastic for automobile member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber-reinforced plastic for automobile members, which is surely injection molded and has good toughness while securing rigidity required for automobile members.SOLUTION: The fiber-reinforced plastic contains a fiber and a resin, wherein as the fiber, a natural fiber and a reinforcing fiber harder than the natural fiber are included. The resin is a thermoplastic resin, and the fiber length of the natural fiber is ≤5 mm. The fiber-reinforced plastic is obtained by mixing the resin with the fiber and injection molding the resulting mixture.

Description

  The present invention relates to a fiber reinforced plastic for automobile members containing fibers and a resin.

  In this connection, Patent Document 1 discloses a fiber reinforced plastic based on a thermosetting resin and containing fibers. In the fiber reinforced plastic of Patent Document 1, lyocell, which is a regenerated cellulose fiber, is used instead of glass fiber that is generally used as a reinforced fiber for the purpose of reducing the load on the global environment. This fiber reinforced plastic basically uses lyocell in the form of woven fabric or knitted fabric in order to obtain the maximum reinforcement effect only by lyocell, which is inferior in strength compared to glass fiber. Is formed by. This fiber-reinforced plastic is suitable for electric and electronic parts such as tanks / containers and copper-clad laminates, but can also be used as an automobile member. However, the hand lay-up molding or the heat compression molding method has poor production efficiency and is not suitable for mass production as an automobile member. Patent Document 1 describes that lyocell can be used not as a woven fabric or a knitted fabric but as a short fiber, and also describes that injection molding is possible.

  Although it is not a fiber reinforced plastic, Patent Document 2 discloses a fiber mat containing fibers and a resin, which is used as an automobile interior material such as an automobile ceiling core material and a door core material. This fiber mat contains inorganic fibers such as glass fibers and plant fibers in a mixed state. After the fibers are entangled into a mat shape, a thermoplastic resin film is laminated on both surfaces and compressed while heating to heat. The plastic resin is melted and impregnated, and then, while the resin is in a molten state, the laminate is pulled in the thickness direction to expand, thereby forming a void.

JP-A-6-257051 JP 2006-316285 A

  By the way, fiber reinforced plastics are generally aimed at improving rigidity, but automobile parts are not only high in rigidity, but also tough from the viewpoint of improving safety by making it difficult to touch and break when touched. Is also required. In addition, productivity that can be mass-produced is also required.

  If fiber reinforced plastic can be injection-molded as in Patent Document 1, an improvement in production efficiency is expected. However, Patent Document 1 does not specifically describe preferred conditions for injection molding. In addition, it is clear that the reinforcing effect is sacrificed if it is used in the form of short fibers that are not entangled with each other in addition to using lyocell that is originally inferior in strength to glass fiber. It is unknown whether rigidity can be obtained. In addition, large-sized members and complex-shaped members cannot be molded by thermosetting resin injection molding. Therefore, it is difficult to actually apply to automobile members.

  Further, the fiber mat of Patent Document 2 is lighter than the case where only inorganic fibers are used by using plant fibers in addition to being lightened by voids. By using together, it is excellent also in combustion resistance than the case where only plant fiber is used. However, since it is intended to be used as a ceiling core material or a door core material, rigidity and toughness for constituting an automobile member alone are not considered. In addition, the manufacturing process is complicated to form voids.

  Accordingly, an object of the present invention is to provide a fiber-reinforced plastic that can be reliably injection-molded and has good toughness while ensuring the rigidity required for automobile members.

  The present invention is a fiber reinforced plastic containing a fiber and a resin, the fiber including a natural fiber and a reinforcing fiber harder than the natural fiber, the resin is a thermoplastic resin, the natural fiber is a fiber It is a fiber reinforced plastic for automobile parts, which has a length of 5 mm or less and is formed by mixing the fibers and injection molding. In the fiber reinforced plastic of the present invention, the content of the fiber in the fiber reinforced plastic is preferably 10% by weight or more, and the content of the natural fiber in the fiber is preferably 30 to 85% by weight.

  According to the fiber reinforced plastic for automobile parts of the present invention, since natural fibers and reinforcing fibers are included as fibers, toughness is ensured while ensuring rigidity. And since resin used as a base is a thermoplastic resin, it is suitable for injection molding. Thereby, a large-sized member or a complicated shape member can be molded. Moreover, since the fiber length of the natural fiber mixed at the time of injection molding is 5 mm or less, it can be reliably injection-molded without the fiber being entangled with the screw or the fiber becoming fooled and clogging the nozzle. Thereby, it can produce continuously and efficiently, and its productivity is high. Further, when the fiber content in the fiber reinforced plastic is 10% by weight or more and the content of the natural fiber in the fiber is 30 to 85% by weight, good toughness can be secured while increasing the rigidity. In addition, an impact resistance improving effect can be obtained.

It is a graph which concerns on the test example 1, and is a graph which shows fiber length and a Charpy impact value. 5 is a bending load curve according to Test Example 2. It is a graph which concerns on the test example 3, and is a graph which shows the content rate and bending rigidity of the natural fiber in a fiber.

  The fiber reinforced plastic of the present invention contains a thermoplastic resin as a main constituent material, and the thermoplastic resin is reinforced with fibers. The fibers include natural fibers and reinforcing fibers that are harder than the natural fibers. By including the soft natural fiber together with the reinforcing fiber that works particularly effectively for improving the rigidity, the rigidity is enhanced while suppressing the deterioration of the toughness inherent in the thermoplastic resin.

  Examples of the thermoplastic resin constituting the fiber reinforced plastic include thermoplastic resins such as polypropylene, polyethylene, polyvinyl chloride, polystyrene, ABS resin, methacrylic resin, polyamide, polyester, polycarbonate, and polyacetal. These thermoplastic resins may be used alone or in combination of two or more.

  Examples of natural fibers include bast fibers such as ramie, kenaf, linen, hemp, and jute, leaf vein fibers such as manila hemp, sisal hemp, and pineapple, leaf fibers such as manila hemp and banana, fruit fibers such as coconut palm, and cotton And plant fibers such as seed hair fibers such as kapok. These plant fibers may be used alone or in combination of two or more. Examples of the reinforcing fiber include glass fiber and carbon fiber. These reinforcing fibers may be used alone or in combination of two or more.

  The amount of total fibers including natural fibers and reinforcing fibers mixed with the thermoplastic resin is preferably 10% by weight or more of the entire fiber reinforced plastic. By setting it as 10 weight% or more, a thermoplastic resin can be reinforced effectively. The fiber content in the fiber reinforced plastic is preferably 20% by weight or more. Thereby, rigidity can be improved more. Most preferably, it is 30% by weight or more. Thereby, the rigidity can be further increased. Although the upper limit of the fiber content in the fiber reinforced plastic is not limited, since the fiber reinforced plastic of the present invention is injection molded as described later, it is 60% by weight or less from the viewpoint of securing moldability in injection molding. It is preferable to do this. In view of the fact that it is a fiber reinforced plastic, it is preferable that a thermoplastic resin is mainly used. Specifically, the fiber content in the fiber reinforced plastic is preferably 50% by weight or less. The proportion of all fibers in the entire fiber reinforced plastic is preferably 10 to 60% by weight, more preferably 20 to 60% by weight, and most preferably 30 to 50% by weight.

  The ratio of the reinforcing fiber and the natural fiber in the whole fiber including the natural fiber and the reinforcing fiber is adjusted in consideration of rigidity and toughness required for the target automobile member. Increasing the proportion of natural fibers increases toughness, and increasing the proportion of reinforcing fibers increases rigidity. In order to achieve both improved toughness and improved rigidity, the content of natural fibers in the entire fiber is preferably 30 to 85% by weight or more. Conversely, the reinforcing fiber content is preferably 15 to 70% by weight. When the content of natural fibers is 30% by weight or more and the content of reinforcing fibers is 70% by weight or less, toughness can be ensured while increasing rigidity. Even if the content of the natural fiber exceeds 85% by weight, the effect of securing toughness can be obtained while increasing the rigidity, but it is preferably 85% by weight or less because the impact resistance can be improved. If the content of natural fibers is less than 30% by weight and the content of reinforcing fibers exceeds 70% by weight, the rigidity is further enhanced, but the toughness, that is, the flexibility, may be significantly impaired, which is not preferable. The toughness is increased as the content of the natural fiber is increased, but the toughness required for the automobile member can be sufficiently ensured until the content of the natural fiber reaches 70% by weight. Therefore, considering that the degree of improvement in rigidity decreases as the content of natural fibers is increased, the content of natural fibers is limited to 70% by weight in terms of increasing rigidity while ensuring good toughness. Is more preferable, and the content of natural fibers is more preferably 30 to 70% by weight. Most preferably, from the viewpoint of securing as high rigidity as possible while ensuring higher toughness, the content of natural fibers in the fibers is 50 to 70% by weight.

  The fiber reinforced plastic of the present invention is molded by injection molding by mixing fibers with a thermoplastic resin. The longer the natural fiber mixed with the thermoplastic resin is, the more likely it is to exert a reinforcing effect, but the fiber length is 5 mm or less. When the fiber length exceeds 5 mm, soft natural fibers tend to cause troubles during molding, such as entanglement with the screw of the molding machine and clogging of the nozzles. If the fiber length is 5 mm or less, injection molding can be performed smoothly. On the other hand, since the reinforcing effect becomes smaller as the fiber becomes shorter, the fiber length is preferably 1 mm or more from the viewpoint of reliably obtaining the reinforcing effect. More preferably, the fiber length is 3 to 5 mm. In that case, the reinforcing effect can be further enhanced.

  The fiber length of the reinforcing fiber contained in the fiber reinforced plastic of the present invention is not particularly limited, but a rigid reinforcing fiber is easily broken and shortened when mixed with a thermoplastic resin. It is preferable to mix them. The fiber length of the reinforcing fiber mixed with the thermoplastic resin is preferably 5 to 10 mm or more. If it is 5 mm or more, a fiber length of about 3 mm can be ensured even if it is shortened during kneading, and a reinforcing effect can be effectively exhibited. Reinforcing fibers with a fiber length exceeding 10 mm cannot be used. However, even if the reinforcing fiber exceeds 10 mm, it is easy to knead because it is not greatly different from the case of using a reinforcing fiber with a length of 10 mm or less by cracking during mixing. Considering the thickness and the like, it is preferably 10 mm or less.

  The fiber-reinforced plastic of the present invention includes both natural fibers and reinforcing fibers, and thus has high rigidity and good toughness. Moreover, because it is injection-molded, it is highly productive, and because it is based on thermoplastic resin, it can be molded into large-sized and complex-shaped members, and can be molded into a desired shape and deployed to various automobile members. it can. For example, it can be applied to interior members such as instrument panels, trims, door modules and base materials for front end modules, back doors and inner panels as exterior members.

[Test Example 1]
In Test Example 1, polypropylene was used as the thermoplastic resin. In order to examine the fiber length, only sisal fiber, which is a natural fiber, is used as the fiber, while changing the length of the added fiber while keeping the fiber content constant at 10% by weight, injection molding is performed to obtain a test piece. It was. For injection molding, an injection molding machine exclusively for long fibers for glass and carbon manufactured by Mitsubishi Heavy Industries, Ltd. was used.

  As a result, when the fiber length exceeds 5 mm, the fiber is entangled with the screw, resulting in shortening of the fiber, nozzle clogging, and remarkably deteriorated moldability. When the fiber length is 5 mm or less, It became clear that molding was possible smoothly. The test piece that could be molded was subjected to a Charpy impact test, and a Charpy impact test value was calculated. The Charpy impact test is performed in accordance with ISO179-1 using a Charpy impact tester (Ueshima Seisakusho IM-1310 Co., Ltd.). The test piece dimensions are 80 mm × 10 mm × 4 mm, the notch size is 2 mm, and the work of the hammer The amount was 2J. The result is shown in FIG.

  As shown in FIG. 1, it was found that the longer the fiber, the higher the Charpy impact value, and conversely, the shorter the fiber, the lower the Charpy impact value. From this result, it became clear that the fiber length is preferably 1 mm or more for use as an automobile member. In order to further enhance the reinforcing effect, it has become clear that the fiber length is preferably 3 to 5 mm.

[Test Example 2]
<Creation of specimen>
Polypropylene was used as the thermoplastic resin. A sisal fiber having a fiber length of 3 mm was used as a natural fiber, and a glass fiber having a fiber length of 6 mm (thickness: 22 μm) was used as a reinforcing fiber. While keeping the fiber content constant at 20% by weight, the balance of natural fiber and reinforcing fiber is No. 1-6, it injection-molded using the general injection molding machine (Sumitomo Heavy Industries, Ltd. SE-185), and produced the plate-shaped test piece (80 mm x 10 mm x 4 mm). Further, as a control, polypropylene (No. 8) containing no fiber, and a conventional material for automobile members (No. 9) used for instrument panels and the like in which a rubber component is blended with polypropylene to improve impact resistance. ) Was injection molded to prepare a test piece. In addition, No. 9 contains no fiber, but contains 20% by weight filler (talc) in the test piece.

<Bending test>
No. About 1-9, the bending test was done based on ISO178. A bending test in which both ends of a plate-shaped test piece (80 mm × 10 mm × 4 mm) were supported and a test force (load) was applied to the center portion was performed, and bending strength and bending rigidity were measured. The results are shown in Table 1. Moreover, the bending load curve which shows the load in a bending test and the displacement of the load direction corresponding to it is shown in FIG.

<Charpy impact test>
No. About each test piece of 1-9, the Charpy impact test was done similarly to the said Test Example 1 based on ISO1799-1, and the Charpy impact test value was computed. The results are shown in Table 1.

  No. containing fiber No. 1-7 and no fiber. 8 and No. 8 containing fibers. 1-7 are No. which does not contain a fiber. It was confirmed that the bending strength and bending rigidity were higher than 8. No. containing fiber In comparison with Nos. 1 to 7, the higher the glass fiber content in the total fiber, which is the total of the glass fiber and natural fiber, the higher the bending strength and the bending rigidity. 1 was the highest. Therefore, referring to the bending load curve of FIG. No. 1 contains natural fiber. Although the maximum load is larger than 2 to 7, when the maximum load is reached, the load suddenly falls and the test piece is broken, so that it is clear that the stickiness (toughness) is lacking. On the other hand, No. including natural fibers in addition to glass fibers. 2-6, no. The displacement after reaching the maximum load was greater than 1. Thereby, it became clear that toughness can be improved by including a natural fiber in addition to a glass fiber compared with the case where only a glass fiber is included.

  Further, as is apparent from FIG. 2, the content of natural fiber in the fiber is 15% by weight. No. 2 shows that the displacement after reaching the maximum load is No. of glass fiber only. Although it is larger than that of No. 1, the linearity (behavior) of the bending load curve is No. 1. It was similar to 1 and was relatively sharp linear. On the other hand, the content of natural fiber in the fiber is 30% by weight. The bending load curve of No. 3 has a no. Unlike 1, the decrease in load after reaching the maximum load was gradual and the displacement was greater. Thereby, it became clear that toughness can be more effectively improved when the content rate of the natural fiber in the fiber containing a glass fiber and a natural fiber is 30 weight% or more.

  Further, the higher the content of the natural fiber in the fiber, the higher the toughness, and the content of the natural fiber in the fiber is 85% by weight. The bending load curve of No. 6 shows that the load drop after reaching the maximum load is extremely slow. It was found that the toughness was sufficiently ensured until the content of natural fibers in the fibers reached 85% by weight. In addition, considering that the effect of improving the rigidity becomes smaller as the content of the natural fiber in the fiber becomes higher, it has become clear that the content of the natural fiber in the fiber is preferably 85% by weight or less. Further, as is apparent from Table 1, when the Charpy impact value is compared, the natural fiber content in the fiber is No. 85% by weight. No. 6 contains no fiber. It was clarified that the Charpy impact value increases as the content of natural fibers in the fiber decreases and the content of glass fibers increases. From this, it became clear that it is preferable that the content of natural fibers in the fibers is 85% by weight or less in that the effect of improving the Charpy impact value is also achieved. From these, it became clear that the content of natural fibers in the fibers is preferably 30 to 85% by weight.

  Further, as is apparent from FIG. 2, the content of natural fiber in the fiber is No. 50% by weight. The bending load curve of No. 4 shows that the load change before and after reaching the maximum load is so gentle that the peak of the line reaching the maximum load is not clear. It was closer to the alignment of nine conventional automotive part materials. And No. whose content rate of the natural fiber in a fiber is 70 weight%. In 5, the load drop after reaching the maximum load becomes more gradual and the amount of displacement increases dramatically. By the time natural fiber content in the fiber reaches 70% by weight, it is inferior to the conventional materials for automobile parts. It became clear that no toughness could be secured. Considering that the effect of improving the rigidity becomes smaller as the content of the natural fiber in the fiber becomes higher, the content of the natural fiber in the fiber is 30 to 70% by weight from the viewpoint of increasing the rigidity while securing toughness to some extent. It became clear that it was more preferable. In addition, it is clear that the content of natural fibers in the fiber is most preferably 50 to 70% by weight from the viewpoint of increasing rigidity while securing toughness at a level substantially the same as that of conventional automotive parts materials. It was.

[Test Example 3]
In Test Example 3, the same raw materials as in Test Example 2 were used, and fiber reinforced plastics having different fiber contents were injection molded to produce a plate-shaped test piece. The fiber content in the fiber reinforced plastic was set to 10, 15, 25, 30% by weight, and furthermore, for each fiber content, a test piece having a natural fiber content of 0, 50, 100% by weight was prepared. . However, when the fiber content was 30% by weight, the content of natural fibers in the fiber was 50, 70% by weight. The bending rigidity was measured for each prepared test piece. The results are shown in FIG. 3 ”as a graph showing the content of natural fibers in the fibers and the corresponding bending rigidity. The graph of FIG. 3 shows the fiber reinforced plastic (No. 1 to 7) having a fiber content of 20% by weight in Test Example 2 above, polypropylene (No. 8) containing no control fiber, and a conventional material for automobile members. The measurement results of the bending test (No. 9) are also shown.

As is apparent from FIG. 3, the fiber reinforced plastic containing fibers is No. 1 containing no fibers. It was reconfirmed that the bending rigidity was increased compared to 8. In addition, if the natural fiber ratio in the fiber is the same, the higher the fiber ratio in the fiber reinforced plastic, the higher the bending rigidity, and conversely, the lower the fiber ratio, the smaller the rigidity improvement effect for thermoplastic resins that do not contain fibers. It became clear again. Here, as clarified in Test Example 2 above, focusing on the case of 85% by weight, which is the maximum value of the natural fiber ratio in the fiber considering that the effect of improving the Charpy impact value is also obtained, the fiber reinforced plastic The fiber content is 10% by weight and the bending rigidity is No. It became clear that it can be ensured equivalent to 9 conventional automotive member materials. As a result, the fiber content in the fiber reinforced plastic is 10% by weight or more, and the natural fiber content in the fiber is 85% by weight or less. It has been clarified that the bending rigidity can be increased to a high level even when compared with a conventional material for automobile members.

Claims (2)

A fiber reinforced plastic for automobile parts containing fiber and resin,
Including natural fibers and reinforcing fibers harder than the natural fibers as the fibers,
The resin is a thermoplastic resin;
The natural fiber has a fiber length of 5 mm or less,
A fiber reinforced plastic for automobile parts, which is formed by mixing the fibers and injection molding. The fiber content in the fiber reinforced plastic is 10% by weight or more,
The fiber reinforced plastic for automobile parts according to claim 1, wherein the content of the natural fiber in the fiber is 30 to 85% by weight.

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