JP2015051550A - Member made of fiber-reinforced plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material which can exhibit required magnetic shield performance without being restricted by a shape, has required physical properties as a structure and achieves light weight as much as possible.SOLUTION: There is provided a member made of a fiber-reinforced plastic which comprises a reinforced fiber composed of at least one ferromagnetic material and a reinforced fiber composed of at least one nonmagnetic material, where the reinforced fiber composed of a ferromagnetic material has magnetic anisotropy.

Description

  The present invention relates to a member made of fiber reinforced plastic having magnetic shielding properties.

  Conventionally, diagnostic equipment using nuclear magnetic resonance imaging (MRI), which generates a strong magnetic field, and equipment / equipment using other superconducting magnets, prevent malfunctions and operation of surrounding electronic equipment. Shielding materials that shield a specific magnetic field have been applied for the purpose of protecting rooms, test rooms, human bodies, and the like. Ferromagnetic materials that can be suitably used as a shielding material include iron oxide, chromium oxide, cobalt, and ferrite, all of which are metals with a large specific gravity. In particular, in a structure such as a vehicle or an aircraft where weight reduction is strongly demanded, there is a limit to the weight reduction of the member even if a metal magnetic anisotropic material that is advantageous in terms of weight is used. In addition, since these materials change their magnetic properties by being deformed, it is difficult to adopt a structure that increases rigidity with a thin plate by bending them by press molding or the like like a normal metal material. For this reason, there is a limit to reducing the thickness from the viewpoint of securing the necessary rigidity, and accordingly, the weight reduction of the member is more difficult than a normal metal member.

  According to Patent Document 1, in the case of a fiber-shaped magnetic body, the shape magnetic anisotropy reflecting the shape becomes dominant, and the longitudinal direction of the fiber becomes the easy magnetization direction. When a fiber-shaped ferromagnetic material is oriented in the material, the material exhibits magnetic anisotropy, and the magnitude of the magnetic anisotropy depends on the degree of orientation. That is, it is shown that the degree of orientation of the ferromagnetic fiber in the material can be measured by measuring the magnetic anisotropy. However, Patent Document 1 does not mention a significant utilization method for orienting ferromagnetic fibers.

  In addition, as shown in Non-Patent Document 1, in order to shield a static magnetic field, it is necessary to reduce the magnetic field of other portions by installing a ferromagnetic material and collecting magnetic flux there. In particular, it has been shown that the use of a magnetic anisotropy material having an easy axis of magnetization in a necessary direction by grasping the flow of a magnetic field at a place to be shielded is desirable in terms of material usage and weight reduction.

JP 2001-91502 A

“Exploring the flow of magnetic fields” Takashi Ayukawa, Railway Technical Research Institute, RRR January 2008 issue

  Therefore, in view of the above problems, the present invention can exhibit the necessary magnetic shielding performance without being restricted by the shape, has the necessary physical characteristics as a structure, and further reduces the weight as much as possible. It is an object to provide a material to be achieved and a member using the material.

As a result of intensive studies, it has been found that the above problem can be solved by using a fiber reinforced plastic having reinforcing fibers made of a ferromagnetic material.
(Claim 1) That is, the present invention includes a fiber reinforced plastic member comprising the reinforcing fiber 4 made of at least one type of ferromagnetic material and the reinforcing fiber 5 made of at least one type of non-magnetic material. Is used.
(Claim 2) If the reinforcing fiber 4 made of a ferromagnetic material is a continuous fiber, the load is efficiently shared in the oriented direction, so that the rigidity and strength of the entire fiber-reinforced plastic are improved.
(Claim 3) When the reinforcing fibers 4 made of a ferromagnetic material are aligned and oriented in several directions, magnetic performance in various directions can be freely designed.

  There are two main causes of magnetic anisotropy in ferromagnetic materials. One is magnetocrystalline anisotropy reflecting crystal symmetry, and the other is shape magnetic anisotropy reflecting the shape of a ferromagnetic material.

  Commonly used magnetic anisotropy materials made of metal are usually supplied as flat plates, but this has little influence on the shape of the magnetic performance, and the magnetic anisotropy is realized by the symmetry of the crystal. Yes. For this reason, when plastic deformation such as bending is performed, the magnetic performance may change.

  On the other hand, in the case of a fiber-shaped ferromagnetic material, the magnetic anisotropy depending on the shape becomes dominant, and the longitudinal direction of the fiber becomes the easy magnetization axis direction. For this reason, as used in the present invention, by aligning the reinforcing fibers 4 made of a ferromagnetic material, the fiber-reinforced plastic including the reinforcing fibers 4 has a magnetic anisotropic material having an aligned easy magnetization axis in a specific direction. Become. Here, since the fibrous ferromagnetic material is used, the magnetic anisotropy effect due to the shape is maintained even if it is formed into a curved surface, and the direction of the magnetic anisotropy can be designed even with a curved member.

In this case, the magnetic characteristics (permeability, saturation magnetic flux density, etc.) in the easy axis direction are determined by the material of the ferromagnetic material used, the diameter and length of the reinforcing fiber as the ferromagnetic material, and the member It is content in. That is, in the present invention, the material, diameter, and length of the reinforcing fiber 4 made of a ferromagnetic material, and further the content of the reinforcing fiber 4 in the member and the direction in which the reinforcing fiber 4 is aligned, are unique to the fiber-reinforced plastic. Similarly to the high degree of freedom in design of strength and rigidity, the magnetic characteristics can be made of a material having a high degree of freedom in design with respect to the direction and size.
(Claim 4) Further, in a magnetic field in which the flow of the magnetic field is generally limited to one direction, the reinforcing fiber plastic including the reinforcing fiber 4 made of a ferromagnetic material in one direction is reduced in terms of weight reduction and material cost. Would be preferable. That is, by setting at least one direction among the directions in which the reinforcing fibers 4 made of a ferromagnetic material are oriented to be a direction along the magnetic field flow field where the member is disposed, A member having high magnetic shielding performance can be provided while suppressing the amount used.
(Claim 5) Moreover, the easy axis direction of the fiber reinforced plastic using the reinforcing fiber made of a ferromagnetic material is usually the longitudinal direction of the fiber having the ferromagnetic material. At this time, from the viewpoint of reducing the influence of the demagnetizing field, it is preferable that the anisotropy between the magnitude of the magnetization in the short direction and the magnitude of the magnetization in the longitudinal direction is large, and the magnitude of the magnetization in the longitudinal direction is short. It is preferable to have 10 times or more in the ratio to the direction. The anisotropy of magnetization in this case can be obtained by measuring the magnitude of magnetization in the plane direction of the fiber reinforced plastic formed in a plate shape. For the measurement of the magnitude of magnetization, for example, a vibration type magnetometer (manufactured by Toei Kagaku Sangyo Co., Ltd., PV-M20-5) can be used.
(Claim 6) At this time, the fiber reinforced plastic obtained by aligning the reinforcing fibers 4 made of a ferromagnetic material in a specific direction has anisotropy in the same direction in terms of strength and elastic modulus. The strength and elastic modulus in the direction may be insufficient. In this case, the reinforcing fibers must be oriented in a direction different from the easy axis direction, which requires strength and elastic modulus. However, in order to increase the strength and elastic modulus in the direction different from the easy axis, considering the above-mentioned anisotropy of the magnitude of magnetization, strengthening made of ferromagnetic material aligned in a specific direction It is preferable to use a reinforcing fiber of a different type from the fiber. More preferably, when the reinforcing fibers 5 made of a non-magnetic material are aligned in the non-oriented direction of the reinforcing fibers 4 made of a ferromagnetic material, the magnetization is secured while ensuring the anisotropy of the magnetization size. A material having high strength and elastic modulus other than the easy axial direction can be provided. That is, it is possible to achieve both magnetic shielding properties other than the direction in which the reinforcing fibers 4 are oriented and material properties such as high strength and high elastic modulus of the fiber reinforced plastic itself.
(Claim 7) Further, it is preferable that the material of the reinforcing fiber 4 made of a ferromagnetic material is a soft magnetic type because a member having high magnetic shielding performance can be provided while suppressing the amount of the fiber used. It is preferable to use a material having a magnetic force of 10 A / m or less. In the present invention, Fe (carbonyl iron), Fe—Ni alloy, Fe—Ni—Mo alloy, Fe—Co alloy, Fe—Cr alloy, Fe—Si alloy, Fe—Si—B alloy, Fe—Al alloy, Fe -Fe alloys such as Cr-Si alloy, Fe-Cr-Al alloy, Fe-Al-Si alloy, Fe-based amorphous alloys, Co-based amorphous alloys such as Co-Fe-Si-B, Mg-Zn ferrite, Mn- Various ferrites such as Zn ferrite, Mn—Mg ferrite, Cu—Zn ferrite, Mg—Mn—Sr ferrite, Ni—Zn ferrite, and Ba ferrite can be used. Among them, a magnetic material having high strength characteristics is preferable, and it is preferable to use an Fe-based amorphous alloy or a Co-based amorphous alloy. Two or more of these ferromagnetic reinforcing fibers may be used in combination.
(Claim 8) The diameter of the reinforcing fiber 4 made of a ferromagnetic material is preferably 0.001 mm or more and 0.3 mm or less. If it is 0.001 mm or more, a fiber-reinforced plastic can be formed without reducing the strength of the fiber. If it is 0.3 mm or less, the influence of the demagnetizing field is small, and the effect of collecting the magnetic flux in the easy magnetization direction can be increased. Moreover, the density of the reinforced fiber made of a ferromagnetic material can be improved by combining two or more types of fibers having different diameters. That is, the magnetic shield effect of the member provided by the present invention can be enhanced by setting an appropriate fiber diameter.

  At this time, the reinforcing fiber 4 made of a ferromagnetic material is not necessarily made of a single material, and the reinforcing fiber itself may be made of a kind of composite material. For example, the surface of a glass fiber or carbon fiber, which is a general reinforcing fiber, can be coated with a ferromagnetic material such as nickel using a general technique to form a reinforcing fiber 4 made of a ferromagnetic material. In this case, since the content of the ferromagnetic material is reduced, the magnetic performance is lowered, but the weight of the fiber-reinforced plastic member can be reduced.

Here, the reinforcing fibers 4 and 5 used in the fiber-reinforced plastic of the present invention may be in a single fiber state or in a strand state in which they are bundled. Moreover, in any case, not the shape of the fiber as it is, but a woven fabric or braided intermediate base material may be formed, for example. The intermediate base material can be in a mixed woven state of reinforcing fibers 4 made of a ferromagnetic material and reinforcing fibers 5 made of a non-magnetic material. In this case, it is necessary to appropriately design the intermediate substrate so that the direction of magnetic anisotropy necessary for the fiber-reinforced plastic member can be realized.
(Claim 9) If the specific gravity of the reinforcing fiber 5 made of a non-magnetic material is smaller than the specific gravity of the reinforcing fiber 4 made of a ferromagnetic material, the weight of the entire fiber reinforced plastic member can be reduced. In particular, in order to reduce the weight while maintaining the strength and elastic modulus, the reinforcing fiber 5 made of a non-magnetic material is oriented with a reinforcing fiber having a higher specific strength and specific elastic modulus than the reinforcing fiber 4 made of a ferromagnetic material. It is preferable. For example, reinforced fibers generally used for fiber reinforced plastics such as carbon fiber and glass fiber are non-magnetic, and generally have higher specific strength and specific elasticity than reinforced fiber 1 made of ferromagnetic material. Therefore, it is desirable to use these reinforcing fibers.

Here, although depending on the use as a structure, the plate-like member is often required to have high bending rigidity in the out-of-plane direction, and has anisotropy with different bending rigidity depending on the direction. This often leads to optimal design. In the present invention, since at least two types of reinforcing fibers are used for an integral fiber-reinforced plastic member, when the member is plate-shaped, the outermost layer far from the center of the thickness of the reinforcing fiber having a higher elastic modulus, Alternatively, it can be designed to increase the bending rigidity efficiently by arranging it at a position close to the surface layer.
(Claim 10) From the same viewpoint, as a means for increasing the bending rigidity, a sandwich structure using a core material, which is employed in a normal fiber-reinforced plastic, can be used.

  The matrix resin used in the fiber reinforced plastic of the present invention is not particularly limited as long as it is a kind of resin that can be used as a matrix resin of a general fiber reinforced plastic. For example, a thermosetting resin such as an epoxy resin, a vinyl ester resin, an unsaturated polyester resin, or a phenol resin can be used. A thermoplastic resin such as nylon resin or polycarbonate resin can also be used.

  The method for molding the fiber reinforced plastic of the present invention is not particularly limited. General fiber reinforced plastic molding methods such as prepreg molding and molding with autoclave and hot press, resin transfer molding (RTM) method, filament winding method, pultrusion molding method, hand layup method, etc. are applicable. is there.

  According to the present invention, while having the necessary magnetic shielding performance, it can exhibit the necessary magnetic shielding performance without being restricted by the shape, has the necessary physical characteristics as a structure, and further, as much as possible A material that achieves weight reduction and a member using the material can be provided.

It is a schematic perspective view of the fiber reinforced plastic flat plate which shows the embodiment of this invention. It is a schematic perspective view which shows an example of the method of aligning the reinforced fiber which consists of a ferromagnetic material. It is a measurement result of the magnetization amount of the flat plate 1 made from fiber reinforced plastics which consists of one embodiment of this invention. It is a measurement result of the magnetization amount of the 0.3 mm thick iron plate in the comparative example 1. In Example 2, it is a measurement result of the magnetization amount of the sample which made the amount of input wires into the half of Example 1. FIG. In Example 3, it is a measurement result of the magnetization amount of the sample which made the input wire length 80% of Example 2. FIG.

  Hereinafter, embodiments of the present invention will be described using examples.

Example 1
FIG. 1 shows a flat plate made of fiber-reinforced plastic in an embodiment according to the present invention. The flat plate 1 made of fiber reinforced plastic includes a central layer 2 and two surface layers 3 made of carbon fiber reinforced plastic.

  FIG. 2 shows a method for forming the central layer 2. The reinforcing fiber 4 is a wire made of iron and having a diameter of about 0.3 mm, which is generally called “number wire # 30”. This is wound around a flat mandrel 6 made of aluminum with a release agent applied in advance so that it does not overlap and a gap is not opened while applying a tension to the required width, and then an epoxy resin is applied, The mandrel was wrapped with a film and cured with a hot press. After curing the epoxy resin, the continuous wire and resin at the end of the mandrel are cut to obtain two fiber reinforced plastic plates with wires as reinforcing fibers from both sides of the mandrel, one of which is trimmed to 100 mm square, and the middle layer 2 was produced.

  “Torayca (registered trademark)” prepreg P3052S-15 manufactured by Toray Industries, Ltd., cut into 100 mm squares with a total of 4 layers, 2 layers per side, on both sides of the produced center layer 2, the carbon fiber of the prepreg is the center layer 2 It arrange | positioned in the direction orthogonal to the wire which is the reinforced fiber 4, and it hardened | cured with the hot press machine and bonded together, and the flat plate 1 made from fiber reinforced plastics was obtained. The weight of the fiber-reinforced plastic flat plate 1 was about 26 g, and the thickness was about 0.9 mm. Among these, the weight of the wire occupied about 16g.

A 9 mm square sample for measuring magnetic properties was cut out from the obtained fiber reinforced plastic flat plate 1, and reinforced arranged in the central layer 2 using a vibration magnetometer (manufactured by Toei Kagaku Sangyo Co., Ltd., PV-M20-5). The direction of the wire which is the fiber 4, and the magnitude | size of the magnetization of the direction orthogonal to it were measured. The measurement results are shown in FIG. The horizontal axis shows the magnitude of the magnetic field applied to the sample, and the vertical axis shows the magnitude of magnetization of the sample. When compared with an applied magnetic field of 20 mT in which the magnetization of the sample is unsaturated, the magnetization value in the wire direction was 16.9 mT, and the magnetization value in the orthogonal direction was 1.6 mT. The maximum value of magnetization was 24.6 mT. That is, the magnitude of the magnetization in the wire direction was 10.5 times that is 10 times or more that in the perpendicular direction, and a large anisotropy of magnetization could be confirmed.
(Comparative Example 1)
A 9 mm square sample for measuring magnetic properties is cut out from a 0.3 mm thick steel plate made of the same material as the wire called “wire # 30” used in Example 1, and a vibration type magnetometer (Toei Scientific Industrial Co., Ltd.) The magnitude of magnetization was measured in the same manner using PV-M20-5). At this time, the weight of the 100 mm square iron plate was about 22 g.

As a result of the measurement, as shown in FIG. 4, the maximum value of the magnetization was 24.6 mT. This almost coincided with the measurement result of the magnetization amount in the wire direction, which is the reinforcing fiber of the central layer in Example 1. From this, it was found that the magnetization characteristics in a specific direction can be improved by comparing the ferromagnetic material input amount due to the shape effect of the ferromagnetic material.
(Example 2)
A fiber-reinforced plastic flat plate 1 having the same configuration as that of the first embodiment and having a wire amount called “number wire # 30” that is half that of the first embodiment, that is, about 8 g per 100 mm square, is prepared. A sample for characteristic measurement was cut out, and the magnitude of magnetization was similarly measured using a vibration magnetometer (manufactured by Toei Kagaku Sangyo Co., Ltd., PV-M20-5).

As a result of the measurement, as shown in FIG. 5, the maximum value of the magnetization was 14.1 mT. This was about half the magnetization amount compared to the measurement result of the magnetization amount in the wire direction, which is the reinforcing fiber 4 arranged in the central layer 2 in Example 1. From this, it was found that if the shape of the ferromagnetic material is the same, the magnetization amount is approximately proportional to the input amount of the ferromagnetic material.
(Example 3)
A fiber-reinforced plastic flat plate 1 having the same configuration and the same wire input amount as in Example 2 was prepared, and a sample for measuring magnetic properties having a wire direction of 7 mm and a direction perpendicular to the wire of 9 mm was cut out. The magnitude | size of magnetization was similarly measured using the total (Corporation | KK Toei Scientific Industrial Co., Ltd. product, PV-M20-5). Wire input decreased by about 20%.

  As a result of the measurement, as shown in FIG. 6, the maximum value of magnetization was 9.7 mT. Compared to Example 2, the amount of magnetization decreased by about 30%. From this, it was found that the shape effect of the ferromagnetic material is not simply proportional, but that the elongated shape can improve the magnetization characteristics in a specific direction compared to the input amount of the ferromagnetic material.

1: Flat plate made of fiber reinforced plastic 2: Central layer (fiber reinforced plastic layer including reinforcing fiber made of ferromagnetic material)
3: Surface layer (fiber reinforced plastic layer containing reinforcing fibers made of non-magnetic material)
4: Reinforcing fiber made of ferromagnetic material 5: Reinforcing fiber made of non-magnetic material 6: Mandrel for molding

Claims (10)

  A fiber reinforcement comprising a reinforcing fiber made of at least one ferromagnetic material and a reinforcing fiber made of at least one non-magnetic material, wherein the reinforcing fiber made of the ferromagnetic material has magnetic anisotropy. Plastic parts.   The fiber-reinforced plastic member according to claim 1, wherein the reinforcing fiber made of a ferromagnetic material is a continuous fiber.   The fiber-reinforced plastic member according to claim 1 or 2, wherein the reinforcing fibers made of a ferromagnetic material are aligned and oriented in several directions.   The at least one direction among the directions in which the reinforcing fibers made of the ferromagnetic material are oriented is a direction along a magnetic field flow field where the member is disposed. Fiber reinforced plastic parts.   The fiber-reinforced plastic member according to claim 3 or 4, wherein the magnitude of magnetization in a direction in which the reinforcing fibers made of a ferromagnetic material are arranged is 10 times or more that in a direction orthogonal to the direction.   The fiber reinforcement according to any one of claims 3 to 5, wherein the reinforcing fiber made of a non-magnetic material is aligned by being aligned in a direction in which the reinforcing fiber made of a ferromagnetic material is not oriented. Plastic parts.   The fiber-reinforced plastic member according to any one of claims 1 to 6, wherein the material of the reinforcing fiber made of a ferromagnetic material is a soft magnetic material.   The fiber-reinforced plastic member according to any one of claims 1 to 7, wherein the diameter of the reinforcing fiber made of a ferromagnetic material is 0.001 mm or more and 0.3 mm or less.   The fiber-reinforced plastic member according to any one of claims 1 to 8, wherein the specific gravity of the reinforcing fiber made of a nonmagnetic material is smaller than the specific gravity of the reinforcing fiber made of a ferromagnetic material.   An outer skin layer including a reinforcing fiber made of at least one type of ferromagnetic material and a reinforcing fiber made of at least one type of non-magnetic material, wherein the reinforcing fiber made of the ferromagnetic material has magnetic anisotropy; and The fiber-reinforced plastic member according to any one of claims 1 to 9, wherein the sandwiched core layer is integrated with the sandwiched core layer.

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