JPH0542620A - Fiber reinforced resin casing and manufacture thereof - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] A thin, lightweight, and rigid fiber reinforced resin (FRP) housing suitable for housings of electric and electronic devices and the like, and inexpensively and simply manufactured. Provide a way to do. A FRP casing substantially composed of a flat surface portion and a side surface portion, wherein the flat surface portion is a low density non-woven fiber sheet such as synthetic paper containing hollow particles between two layers of reinforcing fiber sheets 1 and 2. A sandwich structure is formed by sandwiching and sandwiching with a resin, and the side surface portion has a structure in which only the reinforcing fiber sheets 1 and 2 are solidified with a resin. The housing can be easily molded by using a simple mold that is a combination of a female mold and a male mold formed by pressing a metal plate into a box shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fiber reinforced resin (hereinafter referred to as F
The present invention relates to a structure of a housing (box) made of RP) and a manufacturing method thereof. More specifically, a novel structure of a casing which is preferably lightweight and requires rigidity, such as a cassette tape recorder, a word processor, a radio, a personal computer and other electric / electronic devices, a trunk, a suitcase, and other transportation equipment, and the like. It relates to a method for economically manufacturing a housing.

[0002]

2. Description of the Related Art The above-mentioned housing (box) is generally made of metal and is manufactured by press-molding a metal plate or molding. When specially devising a mounting portion for parts and the like and cutting a screw for assembly, casting is often used. Due to the weight of metal moldings and the moldability of castings in particular, housings have been made of various synthetic resins for a long time. It is widely used because it can be made inexpensively.

However, there is a difference in strength and rigidity between metal and resin, and in the latter case, it is difficult to form a housing having desired physical properties unless a large amount of resin is used. Therefore, the resin is reinforced with fibers, that is, FRP is used. That is, polyester, polycarbonate,
This is the case where very short glass fibers are added to a thermoplastic synthetic resin such as nylon.

As already mentioned, it is already known to make housings from FRP. However, most of the mass-produced products are injection-molded with short fibers mixed in,
In many cases, it is not possible to reduce the weight in order to achieve the desired physical properties. For this reason, those using a relatively long fiber length for reinforcement (for example, SMC) and those using a long fiber sheet for reinforcement (for example, prepreg) have begun to be used partially. However, in reality, these cannot be said to have sufficient physical properties as compared with thickness and weight.

On the other hand, as a material made of FRP, there is a highly rigid structure called a sandwich material. It has a structure in which a foam core such as foamed polyurethane is sandwiched between two surface layers. This one shows some improved physical properties if the skin is FRP, but a thin foam core of the thickness necessary for molding a casing as a sandwich material is not easy to manufacture, and even if it is obtained, , Such a thin foam core is fragile and not easy to handle.

[0006]

DISCLOSURE OF THE INVENTION The present invention is based on the previously known F
By eliminating the drawbacks of the RP housing and making at least the plane part a special sandwich composite sheet structure,
The purpose is to provide a thin, lightweight, and highly rigid housing. Further, the present invention aims to provide a method capable of mass-producing the housing at low cost.

[0007]

The above-mentioned various objects are achieved by the casing and the manufacturing method thereof according to the present invention described later.

That is, the fiber-reinforced resin (F
The casing made of RP) is a casing substantially composed of a flat surface portion and side surface portions formed on the periphery thereof, and at least the flat surface portion is formed by impregnating and solidifying a reinforcing fiber sheet with a resin. layer,
It is characterized in that it is composed of a sandwich composite sheet comprising a second layer in which a non-woven fibrous sheet is impregnated and solidified with a resin and a third layer in which a reinforcing fiber sheet is impregnated and solidified with a resin.

According to the manufacturing method of the present invention, a reinforcing fiber sheet and a resin are first put in a mold for molding a casing, and a non-woven fibrous sheet having a relatively low density is laid on the reinforcing fiber sheet and the resin. The method is characterized in that, after the reinforcing fiber sheet is put on the upper surface, the reinforcing fiber sheet is pressed in that state, and the mold is heated to be molded.

The reinforcing fiber sheet used in the present invention is a woven or knitted product made of continuous filaments such as continuous filaments and spun yarns or the like, and preferably made of fibers having high strength and high elastic modulus. Examples of such fibers include high-strength inorganic fibers such as glass fibers, carbon fibers, alumina fibers, silicon carbide fibers, aramid fibers, polyarylate fibers, and high-strength polyolefin fibers (for example, high-strength fibers called high-polymerization polyethylene fibers). High-strength, high-duras organic fibers are included. Depending on the application, natural fibers such as cotton and hemp, and ordinary synthetic fibers such as polyester fibers, polyamide fibers, polyacrylonitrile fibers, polyolefin fibers, and polyvinylidene fibers are also used. The structure of the woven or knitted fabric is preferably one capable of sufficiently exhibiting the elastic modulus and strength of the fiber, and for example, plain weave, twill weave, suede weave and the like are adopted.

On the other hand, examples of the non-woven fibrous sheet include paper, non-woven fabric and fibrous web having a relatively low density. These are mainly composed of short fibers and / or pulp-like particles (for example, natural pulp, synthetic fibrids, etc.), which are used as one kind of spacer,
Those having a lower density than those of the above-mentioned woven or knitted fabric are preferable.

[0012] The non-woven fibrous sheet is preferably one having a low density such as a needle punched non-woven fabric or a filter paper, but a fibrous web or paper-like material containing lightweight hollow particles is particularly preferable. used.

The web or paper-like material containing such hollow particles can be made of hollow particles and fibers and / or fibrils. Either a wet method or a dry method can be adopted as a manufacturing method thereof. A typical dry method is web formation using a card, and for the purpose of the present invention, a card web can be used as it is, but needle punching is more preferable. At this time, the hollow particles can be added at the time of being applied to the card or on the way thereof, or at the time of performing needle punching.

On the other hand, a typical example of the wet method is a slurry method, which is a dilute slurry which is then filtered or precipitated to form a web (or a paper-like material). It is preferable to filter it out, and the hollow particles are usually added at the time of forming a slurry.

Examples of lightweight hollow particles include completely hollow particles such as glass beads and silica beads, and porous particles such as shirasu balloon and silica balloon. Polyvinylidene chloride and other polymer particles containing hydrocarbons and halogen compounds in the polymer particles, such as Matsumoto Yushi-Seiyaku Co., Ltd.'s "Microsphere", Expancel's "Expansel", polystyrene and foaming agent Organic hollow particles that have been expanded and expanded, such as "Eslen beads" manufactured by Seihin Co., Ltd., may also be mentioned.

The fibers or fibrils to be made into webs, papers, etc. together with the hollow particles include fibers made of polyester, polyamide, aramid, polyacrylonitrile, polyolefin, vinyl polymer, etc., fibrillated or precipitated. Examples of the fibrids include so-called polymerized ones (those capable of obtaining fibrid during polymerization). Examples of such polymerized fibrids include polyolefins, especially polyethylene, and aramids, especially polyparaphenylene terephthalamide. Of course, a mixture of these may be used, and natural pulp or the like can also be used.

The fibers that make up the web, paper-like material, etc. are often short fibers, which are short fibers having a length and diameter suitable for forming a web (or paper-like material). The length and diameter differ depending on the web-making method used. However, usually, the diameter is preferably 1 to 50 μm, particularly preferably 4 to 20 μm. The length is preferably 1 to 50 mm, particularly preferably 5 to 20 mm.

Examples of the fibrils such as webs and paper-like materials include branched short fibers, beaten and finely divided fibers, and fine film-like materials. Of these, the method described in JP-B-61-2004 or JP-B-60-56801 is often preferable, but JP-B-3
Synthetic fibrids and natural pulp-like particles produced by the method described in JP-A-5-11851 and JP-B-37-5732 can also be used. When a web or the like is produced using fibrils, it is preferable to use a wet method. In this case, the beating degree (freezing degree) of the fibrils is 80 ° SR or less, preferably 50 ° SR or less based on the Shopper-Riggler method. If the freeness is larger than this, it may be difficult to handle as a raw material for the method of the present invention.

The resin used in the present invention is preferably a thermosetting resin. Examples of such a thermosetting resin include an epoxy resin, an unsaturated polyester resin, a vinyl ester resin, a phenol resin, a cycloolefin resin (for example, a commercially available product under a trademark such as "Meton"). In the case of a thermosetting resin, it can be used by impregnating reinforcing fibers, but it is also preferable to inject the fluid thermosetting resin into a molding die before introducing the reinforcing fibers.

In the case of a thermoplastic resin, it is preferable to weave it together with the reinforcing fiber as the matrix fiber, and heat and melt it in the mold to give the resin fluidity and mold it. Therefore, those having a low melt viscosity are preferable.

In the present invention, it is possible to change the type of resin for each layer described later, but it is preferable to use the resin having the same composition as a whole.

In the present invention, at least the flat surface portion (bottom plate portion) of the housing is formed of a thin layer sandwich composite sheet structure having mass productivity.

In a preferred embodiment, the sandwich composite sheet structure described above is used which has a core (second layer) consisting of a reinforced syntactic foam core.

The feature of this embodiment is that the front surface and the back surface (first layer and third layer) are composed of a fiber reinforced resin (FRP) phase,
A reinforced syntactic foam core is used in place of a conventional thin foam core as a core portion (second layer) interposed therebetween, and a concrete example of a method of carrying out is a hollow hollow particle as a core layer. It is to use a web or a paper-like material containing.

Foam cores, which are generally thin and are particularly hard and light, are fragile. Although a soft foam core can be obtained which is hard to break, it is not suitable as a core of a sandwich material. On the other hand, the syntactic foam core has higher strength than these, and the core can be formed at the same time when the sandwich composite sheet is formed (for example, Japanese Patent Publication No. 58-58).
21579). In addition, a relatively thin core layer can be produced by such a molding method.

The present inventor has found that such a sandwich composite sheet is particularly effective in a housing, and found that it is preferable to reinforce the syntactic foam core with a short fiber or the like, and arrived at this embodiment. did. That is, according to this embodiment, there is provided a casing in which at least the plane portion of the casing is a sandwich composite sheet having a reinforced syntactic foam core as a core material.

If such a casing has a sandwich structure including the above-described core portion up to the end of the molded product, the surface layer portion often separates from the core portion at the end portion. Side part that hits (corresponding to rib in mechanical structure)
In many cases, it is preferable not to use the above-mentioned sandwich structure.

A housing having such a sandwich composite sheet as a plane portion is made of a web or paper-like material containing hollow particles.
Sandwiched between the reinforcing fiber sheets and solidified with resin to form a web or paper-like material containing hollow particles in the flat part (bottom plate).
The side surface (wall surface) can be made not to be a sandwich composite sheet if it is formed so as to be sandwiched only between corresponding portions.

In such molding, for example, a resin having a low viscosity or its raw material is put in a mold, a reinforcing fiber sheet, a web or a paper-like material containing hollow particles is overlaid, and the reinforcing fiber sheet is overlaid thereon. It can be carried out by a molding method. Since this method does not require high pressure at the time of molding, it is also possible to use a mold having no strength, for example, a simple mold obtained by press molding a metal plate of steel, brass, aluminum alloy or the like. In particular, it is convenient and advantageous to use a die in which a gap is provided between the press-molded male and female dies and excess resin is discharged to the outside of the system through this gap.

Next, the above-described embodiment will be described in detail with reference to the drawings. FIG. 1 is a simplified cross-sectional view illustrating an example of the structure of a housing according to the present invention, in which A is a bottom plate portion that is a flat surface portion of the housing, and B is a side surface portion of the housing. It is the surrounding wall part.

In the present invention, the bottom plate portion A has a low density non-woven fabric made of a web or paper-like material containing hollow particles between reinforcing fiber sheets 1 and 2 made of two layers of carbon fiber woven fabric or the like. The fibrous sheet 3 is laminated so as to be interposed, and has a structure in which a resin is impregnated and cured throughout. On the other hand, the peripheral wall B
The resin is impregnated and cured in the two layers of the reinforcing fiber sheets 1 and 2. That is, this portion does not include the non-woven fibrous sheet 3 and is designed to have high strength.

FIG. 2 is a simplified sketch drawing showing an example of a mold for molding a casing used in the method of the present invention. In the figure, 4 is a female mold in which a metal plate is press-molded into a box shape and has an upward concave,
Reference numeral 5 is also a male mold having a downward convex shape formed by pressing a metal plate. As shown in the figure, the male and female molds are used by assembling the latter by fitting them into the former, and when both are assembled, an appropriate gap S is formed on both sides, and molding is performed from here. Occasionally, excess resin is discharged.

FIG. 3 is a simplified cross-sectional view showing how the casing is molded. In the figure, a low-density non-woven fibrous sheet 3 made of a web or paper-like material containing hollow particles is sandwiched between the reinforcing fiber sheets 1 and 2, which is located only in the bottom plate portion B. That is, the liquid resin 6 is put into the female mold 4, the reinforcing fiber sheet 1, the non-woven fiber sheet 3 such as a web or paper containing hollow particles, and the reinforcing fiber sheet 2 are put in this order, and the weight 7 The male mold 5 on which is placed is pressed to impregnate the whole body with resin.

The reinforcing fiber sheets 1 and 2 placed in the mold, the web or paper-like material 3 containing hollow particles, and the resin 6 are introduced into a heating furnace together with the mold, the resin is cured, and molding is performed. The mold is taken out of the heating furnace, cooled, removed from the mold, and the side surface of the molded product is cut at a predetermined position to form a predetermined FRP housing.

The heat curing treatment can be performed in a batch system, but the mold containing the above-mentioned molding materials is placed on a belt conveyor, continuously introduced into the heating furnace, and then exited from the heating furnace. It is also possible to employ a continuous method consisting of transporting in air and cooling.

Further, in the method of the present invention, only the female mold is used as shown in FIG. 4, and the reinforcing fiber sheet 1, the non-woven fiber sheet 3 containing hollow particles, and the reinforcing fiber sheet 2 are placed in this mold in this order. They are piled up, and at that time, the above-mentioned sheets are impregnated with the uncured resin in advance, or the uncured resin is put in the mold, and the whole is uniformly pressed against the inner surface of the mold by a small roller 8 to apply the uncured resin. It is also possible to impregnate each layer with resin while shaping. Also in this case, a desired housing-shaped molded product can be obtained by placing the mold (female mold) in a heater and curing the resin.

Incidentally, in the case of the present invention, it is possible to partially thicken a necessary portion such as a position where a screw hole for attaching a component is provided. For example, during molding, the gap between the male and female dies may be adjusted to form only a part of the four peripheral wall portions B into a thick wall.

Such a molded article of the present invention has a bending strength,
At the same time, physical properties such as elastic modulus and cost performance as well as aesthetics such as fashion will be satisfied. One of the reasons why such a preferable molded product is obtained is that the housing usually has a side wall, and this side wall serves as a rib of the bottom plate as a structure.

In the embodiment shown in FIGS. 1 to 4 as described above, the low density non-woven fibrous sheet 3 is provided between the reinforcing fiber sheets 1 and 2.
As a web or paper-like material containing hollow particles as an intervening material, instead of this web or paper-like material, other low-density non-woven fibrous sheet such as filter paper, non-calendered aramid paper, aramid fiber The needle-punched non-woven fabric, glass fiber chopped strand mat, and the like can be used. It is preferable that these contain bubbles or voids.

The materials and / or configurations of the upper and lower reinforcing fiber sheets 1 and 2 may be the same, but may be different. For example, the reinforcing fiber sheet 1 on the surface layer side of the housing is a high-quality carbon fiber (continuous filament) woven fabric in consideration of aesthetics, fashionability, etc., and the other reinforcing fiber sheet 2 on the inner side is glass. The cost may be reduced as a woven fabric of fibers (continuous filaments). Also, in this case, if the necessary patterns, characters, marks, etc. are printed or pasted on the non-woven fibrous sheet 3 used for the core, it can be recognized through the glass fiber woven fabric after molding, so The product name, serial number, and other necessary information can be displayed semipermanently. Although carbon fiber is excellent in strength and elastic modulus, it may be weak in impact, and in order to compensate for this drawback, aramid, allylate,
It may be preferable to use organic fibers such as high-density polyolefin in combination.

[0041]

According to the present invention as described above, a thin and lightweight FRP using a sandwich composite sheet and having good physical properties is used.
A housing is provided, and the method of the present invention allows such housing to be inexpensively and easily molded. Such housings include word processors, personal computers, AV equipment, audio equipment, trunks,
It is effectively used in fields such as suitcases.

[0042]

EXAMPLES Next, the present invention will be described in detail with reference to examples. These are for explanation of the present invention, and the present invention is not limited thereto. In the following examples, “part” means “part by weight” unless otherwise specified.

[0043]

[Example 1] A fibrid of aramid mainly composed of polymetaphenylene isophthalamide was added to Japanese Patent Publication No. 59-4769.
A prototype was produced using the device shown in No. 5. This fibrid is based on the manufacturing method described in Japanese Examined Patent Publication Nos. 35-11851 and 37-5732. The freeness of the obtained fibrids was 51 ° SR.

50 parts of this fibrid and 50 parts of glass hollow particles (M-28) manufactured by Asahi Glass Co., Ltd. were mixed to make paper with a tappy standard machine, and a basis weight of about 100 g /
m ² of synthetic paper was obtained.

On the other hand, carbon fiber cloth (T-400 woven fabric manufactured by Toray Co., Ltd., basis weight of about 200 g / m 2 as a reinforcing fiber sheet)
² ) prepared.

Also, 100 parts of epoxy resin "Epicoat 807" manufactured by Yuka Shell Co., Ltd. and "Epomate YLH0" are used.
A mixed resin was prepared by mixing 31 parts of "06".

Two aluminum plates were pressed to form a box-shaped mold. There are a female mold of about 200 mm x 100 mm and a male mold smaller by about 2 mm each.

The above synthetic paper was cut into pieces each having a size of about 5 mm smaller than that of the female mold. Also, two carbon fiber cloths each larger than the mold by about 20 mm were cut out. Synthetic paper and carbon fiber cloth were each dipped in warm mixed resin, and both were thoroughly impregnated with the mixed resin.

The inner surface of the female mold is coated with the mixed resin, the carbon fiber cloth impregnated with the mixed resin and then the synthetic paper impregnated with the mixed resin are laid, and the carbon fiber cloth impregnated with the mixed resin is further placed thereon. I put a male mold.

A weight was placed on the male mold and placed in a ventilated steam dryer at 105 ° C. After about 1 hour, it was taken out from the dryer. At this time, the excess resin was discharged from the gap between the male and female molds.

After cooling, the case-shaped molded product was taken out, and the side surface of the obtained molded product was cut off from the bottom plate at a position of 5 mm,
A case with a depth of 5 mm was obtained. This product had a good appearance and a corresponding strength. The specific gravity is about 0.98, and the plate-shaped sample with only the bottom plate cut out has a bending strength of 18.6 kg / m.
The m ² and the elastic modulus were 1058 kg / mm ² .

[0052]

Example 2 A portable cassette tape player was selected as a product model, and a concave master of this housing model and a convex master whose entire surface is 1 mm smaller than the concave master were prepared.

A steel plate for pressing was obtained and cut into a predetermined size. This steel plate was pressed using the above masters to obtain respective steel plate molded products. This molding (mold)
The case depth was 10 mm deeper for the female (outer type) and 20 mm deeper for the male (inner type). The inner surface of the female mold and the outer surface of the male mold were “Teflon” coated.

Aramid fibrid 60 as in Example 1
40 parts of short fibers obtained by cutting polymetaphenylene isophthalamide fiber (registered trademark "Conex") manufactured by Teijin Ltd. into a fiber length of 2 mm was mixed and paper-made with a tappy standard machine, and a basis weight of 100 g / m ² Aramid paper. This was cut into 1 mm smaller sheets from each side of the female bottom plate.

As a reinforcing fiber sheet for the surface layer, Toray Industries, Inc.
Carbon fiber T-400 cloth (approx.
m ² ), glass cloth WF-181-100BV manufactured by Nitto Boseki Co., Ltd. was obtained as the reinforcing fiber sheet for the inner layer. Two pieces of cloth each having a length of 10 mm on each side of the cloth bottom plate were cut from these cloths.

100 parts of epoxy resin "Epicoat 807" and "Epomate YLH006" manufactured by Yuka Shell Co., Ltd.
31 parts was mixed to prepare a mixed resin.

The mixed resin was put into a female mold, the carbon fiber sheet cutting cloth, the aramid paper, and the glass fiber sheet cutting cloth were placed in the female mold in that order, and the male mold was placed thereon and a weight was further placed thereon. The resin overflowed between the male and female molds and was wiped off.

This was placed in a dryer at 95 ° C. and kept for 2 hours. The product was taken out from the dryer and cooled, and the mold was removed to obtain a casing-shaped molded product. The side surface of this molded product was cut out at a predetermined position. Thus, a portable cassette tape player housing of sandwich material having a syntactic foam core as a core material was obtained.

The results of a bending test with the bottom plate cut off were as follows: strength 19.8 kg / mm ² , elastic modulus 1097 kg /
It was mm ² .

[0060]

[Example 3] The carbon fiber woven fabric in Example 2 was a mixed weave plain weave of carbon fiber T-400 manufactured by Toray Industries, Inc. and aramid fiber "Technora" manufactured by Teijin Limited, and the aramid paper was changed to No. 2 filter paper. A molded product was obtained in exactly the same manner. A beautiful and fashionable case with sufficient rigidity and strength was obtained.

[Brief description of drawings]

FIG. 1 is a simplified sectional view illustrating a sectional structure of a housing according to the present invention.

FIG. 2 is a simplified sketch drawing illustrating a mold used in the method of the present invention.

FIG. 3 is a simplified sectional view showing an example of molding in the method of the present invention.

FIG. 4 is a simplified sectional view showing another example of the method of the present invention.

[Explanation of symbols]

 1 Reinforcing Fiber Sheet 2 Reinforcing Fiber Sheet 3 Nonwoven Fibrous Sheet 4 Female Mold for Molding 5 Male Mold for Molding 6 Liquid Resin 7 Molding Weight 8 Roller A Bottom Plate of Housing B Housing Peripheral wall part S Gap between male and female molds

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Claims (14)

[Claims] 1. A casing comprising a substantially flat surface portion and side surface portions formed on the periphery thereof, wherein at least the flat surface portion has a first layer formed by impregnating and solidifying a reinforcing fiber sheet with a resin, a non-woven fiber material. A fiber-reinforced resin casing, comprising a sandwich composite sheet comprising a second layer in which a resin is impregnated and solidified and a third layer in which a resin is impregnated and solidified in a reinforcing fiber sheet. 2. The housing according to claim 1, wherein the outer surface side of the housing in the sandwich composite sheet is composed of a layer obtained by impregnating and solidifying a resin into a long fiber woven fabric made of carbon fibers and / or high-strength organic fibers. .. 3. The housing according to claim 1, wherein an inner surface side of the housing in the sandwich composite sheet is composed of a layer obtained by impregnating and solidifying a glass fiber woven fabric with a resin. 4. A second member of the sandwich composite sheet.
The housing according to claim 1, 2 or 3, wherein the layer is a relatively low density paper-like material, a non-woven fabric or a fibrous web impregnated and solidified with a resin. 5. The second of the above sandwich composite sheets
The housing of claim 4, wherein the layer is a low density layer containing hollow particles. 6. The casing according to claim 1, wherein the resin impregnated and solidified in each layer of the sandwich composite sheet is the same resin. 7. The housing according to claim 1, wherein the side surface of the housing is made of a composite sheet containing no nonwoven fibrous sheet. 8. The housing according to claim 1, wherein a specific position of a flat surface portion or a side surface portion of the housing is formed thick. 9. A resin and a reinforcing fiber sheet are placed in a mold for molding a casing, a non-woven fibrous sheet is overlaid thereon, and the reinforcing fiber sheet is further placed thereon, and then pressed in that state. ,
A method for manufacturing a housing made of fiber reinforced resin, which comprises molding the mold by heating. 10. The method according to claim 9, wherein a relatively low density paper-like material, a fibrous web or a non-woven fabric is used as the non-woven fibrous sheet. 11. A non-woven fibrous sheet comprising a paper-like material containing hollow particles, a fibrous web or a non-woven fabric.
Or the production method according to 10. 12. The method according to claim 9, 10 or 11, wherein an uncured thermosetting resin is used as the resin. 13. The manufacturing method according to claim 1, wherein a metal mold is press-molded to form a box-shaped metal mold. 14. The method according to claim 13, wherein a metal mold is used which is a combination of a female mold formed by pressing a metal plate into a box shape and a male mold fitted therein.