JPH0229496B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a fiber reinforced laminate used as a structural member and a method for manufacturing the same. [Prior Art] Various properties of fiber-reinforced laminates exhibit large anisotropy depending on the orientation of the reinforcing material, and improving the properties in the non-reinforced direction has become an important issue. Conventionally, this anisotropy can be solved by randomly orienting the reinforcing material in a certain plane or by creating a multilayer laminate in which the fibers have different orientation directions in various layers. A common technique was to make it essentially isotropic. However, as the application of composite materials progresses, the number of products with complex shapes and thick walls increases, and the characteristics that require the orientation of reinforcing materials in the direction perpendicular to the laminated plane rather than in the in-plane direction, especially interlaminar shear strength, are becoming a problem. I'm getting used to it. Although measures have been taken to deal with the anisotropy in the in-plane direction as described above, measures have not been taken to deal with the anisotropy in the direction perpendicular to the laminated plane. Conventionally, as a similar method, a method has been proposed in which whiskers are mixed in to reinforce the interlayers of prepregs when laminating long fiber prepregs (for example, Japanese Patent Application Laid-Open No. 60-38145). As shown in Fig. 3, this technology involves winding and laminating prepregs 1 containing long fibers to form a tubular body, and impregnating a scrim sheet 3 with a thermosetting synthetic resin mixed with whiskers 2. A whisker layer can be formed by polymerizing the scrim sheet 3 onto the prepreg 1 and winding it, or by applying whiskers 2 mixed with a solvent to one side of the prepreg 1, or by electro-flocking or spraying the whiskers 2. is formed and hardened by heating and pressurizing to obtain a tubular body having a whisker layer between the long fiber layers. [Problems to be solved by the invention] As described above, even in the prior art, whiskers are oriented between layers of long fiber layers, but most of these whiskers are oriented in the in-plane direction of the long fiber lamination surface. The problem is that the fibers are not oriented in the direction perpendicular to the laminated plane of the long fibers to improve the interlaminar strength, and the auxiliary effect of the reinforcing material cannot be fully utilized. It was hot. This invention was made to solve the above-mentioned problems, and it provides a three-dimensional reinforced laminate in which the reinforcing material is oriented in a direction perpendicular to the long fiber laminate surface and has high reinforcement efficiency due to magnetic field orientation, and its production. The purpose is to obtain a method. [Means for Solving the Problems] The three-dimensional reinforced laminate of the first aspect of the present invention comprises laminated non-magnetic long fibers and ferromagnetic material oriented in a magnetic field perpendicular to the laminated surface of the long fibers. It comprises short fibers of the body, and a hardened matrix containing the long fibers and the short fibers in the orientation state. In the method for manufacturing a three-dimensional reinforced laminate according to the second aspect of the present invention, a combination of ferromagnetic short fibers and non-magnetic long fibers is placed in a mold placed in a magnetic field, and a matrix is formed. In this method, only the short fibers of the ferromagnetic material are oriented in a magnetic field in a direction perpendicular to the laminated surface of the long fibers by magnetic force in an impregnated state, and then hardened. In this invention, a mold is placed in a magnetic press with magnetic poles, and the direction of the magnetic lines of force is set perpendicular to the laminated surface of the long fibers, so that only the short fibers, which are ferromagnetic substances, are oriented perpendicularly to the laminated surface of the long fibers by the magnetic force. The matrix is cured in this state to obtain a three-dimensional reinforced laminate. The length of the short fibers is set to 100 μm or less, which is smaller than the laminated thickness of each long fiber when pressurized, so that the already oriented short fibers are not deflected by the pressure applied during molding, and to ensure a sufficient reinforcing effect. In order to achieve this, it is preferable to set the aspect ratio to 20 or more. The three-dimensional reinforced laminate of this invention is manufactured as follows. First, a mold is installed between the magnetic poles of a magnetic press. When the mold is made of a combination of magnetic and non-magnetic materials, when a magnetic field is generated, lines of magnetic force are generated between the magnetic materials. Since the short fibers of the ferromagnetic material are oriented in the direction of these lines of magnetic force, the mold is installed so that the direction of the lines of magnetic force is perpendicular to the laminated surface of the long fibers. The long fibers of the unidirectional material or cloth material mixed with short fibers of ferromagnetic material are placed in this mold, and the matrix is vacuum impregnated into the mold. Next, a magnetic field is generated to orient only the short ferromagnetic fibers perpendicular to the laminated surface of the long fibers. At this time, an ultrasonic vibrator is attached to the mold, and the short fibers inside the mold are vibrated by ultrasonic vibration, and the short fibers are uniformly dispersed so that they do not float or settle, making it easier to align them using magnetic force. is preferable. In this state, the mold is pressurized to harden the matrix to obtain a three-dimensional reinforced laminate. When ceramic fibers are used as the nonmagnetic long fibers, fibrous inorganic compounds such as carbon fibers and glass fibers can be used, and in this case, resins, metals, ceramics, etc. can be used as the matrix. In addition, when using organic fibers, synthetic fibers such as polyethylene terephthalate fibers and aramid fibers, and natural fibers such as silk and cotton can be used.In this case, if metals or ceramics are used as the matrix, the molding temperature is high and organic fibers can be used. Thermosetting or thermoplastic resins are preferable as the matrix because they cause thermal decomposition. As short ferromagnetic fibers, iron oxide particles or metal particles with an aspect ratio of 20 or more, ferromagnetic whiskers with an aspect ratio of 20 or more and a fiber length of 100 μm or less, or whiskers coated with a ferromagnetic material can be used. [Function] The three-dimensional reinforced laminate produced as described above is solidified by a matrix with the short fibers oriented perpendicular to the laminated plane of the long fibers, so the interlaminar shear strength is significantly improved, and all types of It is reinforced against stress and is suitable as a structural member. [Example] Hereinafter, an example of the present invention will be described with reference to the drawings. Example 1 FIG. 1 is a front view of a three-dimensional reinforced laminate manufacturing apparatus used in the example, and FIG. 2 is a vertical cross-sectional view of its mold, and in the figure, 4 is a magnetic press;
It has magnetic poles 5 on the upper and lower pressurizing parts. The diameter of the magnetic pole 5 is 300 mm. A mold 6 is interposed between the magnetic poles 5, and is composed of magnetic material portions 6a on the upper and lower surfaces and non-magnetic material portions 6b on the side surfaces. 7 is an ultrasonic vibrator.
The non-magnetic long fibers 8 made of CFRP cloth material are plain woven with warp and weft densities of 17.5 threads/25 mm.
The dimensions are 100mm x 100mm and the thickness is 0.14mm. These long fibers 8 are laminated one by one in a mold 6, and at this time, ferromagnetic short fibers 9 made of iron oxide particles having a diameter of 0.03 μm and a particle length of 0.6 μm are uniformly sprinkled between each layer.
The volume content of long fibers 8 and short fibers 9 with respect to the molding volume is 50% and 10%, respectively. After the fibers are laminated in this manner, the epoxy resin is press-fitted into the mold 6 while evacuating the inside of the mold 6. At this time, the press-fitting is performed gradually so that the laminated long fibers 8 and short fibers 9 are not disturbed. Next, press the mold 6 into the magnetic press 4.
The short fibers 9 in the mold are vibrated by an ultrasonic vibrator 7 installed between the magnetic poles 5 of the mold 6, and the short fibers 9 in the mold are prevented from being restrained from interfering with the orientation of the particles, so that they are uniformly dispersed. do. In this state, magnetic pole 5
A magnetic field is generated, and lines of magnetic force are generated between the magnetic material portions 6a in the mold 6. The long fibers 8 made of non-magnetic material are not affected by the lines of magnetic force, but the short fibers 9 made of ferromagnetic material are oriented in the direction of the lines of magnetic force, that is, in the direction perpendicular to the long fibers 8. Then, heating is performed by a heater embedded in the mold 6, and the magnetic pole 5
Pressure is applied to harden the material. Since the viscosity of the epoxy resin changes due to heating, vibration and magnetic field orientation are performed when the epoxy resin has a low viscosity so that the short fibers 9 are easily oriented. After curing, test piece A (height 3mm
× Width 6 mm × Length 20 mm) and interlaminar shear strength
Specimen E when F _IS was measured and no magnetic field was applied
and test piece F with only long fibers 8 made of cloth material.
The results shown in Table 1 were obtained. Examples 2 to 4 In Example 1, the type of short fiber 9 was changed to
0.03μm, particle length 0.7μm metal particles, diameter 0.3μm
m, iron whiskers with fiber length 75 μm and diameter 0.6 μm,
Table 1 shows the measurement results of the interlaminar shear strength of test pieces B, C, and D of Examples 2 to 4 in which nickel-coated SiC whiskers with a fiber length of 80 μm were used.

〔Effect of the invention〕

As described above, according to the present invention, the matrix is hardened by orienting short fibers in a direction perpendicular to the laminated surface of long fibers, so that the interlaminar shear strength, which was a weak point of conventional laminates, can be significantly improved. I can,
This has the effect of producing a high-quality laminate that can withstand all types of stress.

[Brief explanation of drawings]

FIG. 1 is a front view of a three-dimensional reinforced laminate manufacturing apparatus according to an embodiment of the present invention, FIG. 2 is a vertical sectional view of a mold thereof, and FIG. 3 is a view of a material forming a tubular body according to a conventional manufacturing method. FIG. 3 is a partially cutaway plan view. In each figure, the same reference numerals indicate the same parts, 4 is a magnetic press, 5 is a magnetic pole, 6 is a mold, 6a is a magnetic material part, 6b is a non-magnetic material part, 7 is an ultrasonic vibrator, 8
9 is a long fiber, and 9 is a short fiber.

Claims (1)

[Claims] 1 Laminated non-magnetic long fibers, ferromagnetic short fibers oriented in a magnetic field in a direction perpendicular to the laminated surface of the long fibers, and the long fibers and short fibers in the oriented state. A three-dimensional reinforced laminate characterized by having a hardened matrix incorporated therein. 2. The three-dimensional reinforced laminate according to claim 1, wherein the ferromagnetic short fibers are iron oxide particles or metal particles with an aspect ratio of 20 or more. 3. Three-dimensional reinforcement according to claim 1, wherein the ferromagnetic short fibers are ferromagnetic whiskers with an aspect ratio of 20 or more and a fiber length of 100 μm or less, or whiskers coated with ferromagnetic material. laminate. 4 The non-magnetic long fibers are ceramic fibers,
The three-dimensional reinforced laminate according to any one of claims 1 to 3, wherein the matrix is resin, metal, or ceramic. 5. The three-dimensional reinforced laminate according to any one of claims 1 to 3, wherein the long fibers of the non-magnetic material are organic fibers, and the matrix is a thermosetting or thermoplastic resin. body. 6 A combination of ferromagnetic short fibers and non-magnetic long fibers is placed in a mold placed in a magnetic field, and with the matrix impregnated, only the ferromagnetic short fibers are subjected to magnetic force. A method for producing a three-dimensional reinforced laminate, which comprises curing the long fibers by orienting them in a magnetic field in a direction perpendicular to the laminate surface. 7. The method for manufacturing a three-dimensional reinforced laminate according to claim 6, characterized in that the fibers are vibrated by ultrasonic vibrations during magnetic field orientation to facilitate orientation. 8. The method for manufacturing a three-dimensional reinforced laminate according to claim 6 or 7, wherein the mold is made of a magnetic material and a non-magnetic material, and a magnetic force is generated between the magnetic materials.