JPS595406B2 - Aligned prepreg and its manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aligned prepreg used as a molding material for fiber-reinforced plastics.

Prepreg for fiber-reinforced plastics is made by impregnating thermosetting resin with nonwoven fabric, yarn, cloth, or chopped strand fibers, unidirectional fibers, or a combination of these. The prepared prepregs have different characteristics depending on the fibers used in their manufacture, and are used for various purposes depending on these characteristics.

Among these prepregs, prepregs obtained using fibers aligned in one direction can easily be made into thin sheets or tapes, so they are suitable as molding materials for long tubular bodies, laminates, etc. For example, it is used in high-strength composite materials such as leisure sports equipment such as golf club shafts and ski bodies, automobiles, and aircraft materials.

Conventionally, this type of prepreg is made by impregnating resin into bundles of multifilament fibers aligned in one direction, and then arranging multiple fiber bundles in the same direction so that each bundle is adjacent to each other. and a bundle are joined together with a resin impregnated into these bundles and formed into a sheet or tape shape.

The unidirectionally aligned prepreg obtained by this conventional method is made up of bundles of multifilament fibers that are parallel to each other in one direction bonded together using only the bonding force of the uncured resin. The resistance to change is small, and the combination of these conditions weakens the binding force between the fiber bundles.

As a result, when conventional prepregs are stored for long periods of time or used, temperature changes create gaps between the bundles of prepreg fibers, and sometimes they become separated in layers. When manufacturing molded products using prepreg, mechanical stress and thermal changes weaken the binding force between fiber bundles and create gaps and separations, which deteriorates the quality of the prepreg or the quality of the molded product. It has the disadvantage of Furthermore, the strength in the alignment direction and the direction perpendicular to the alignment direction of the fiber-reinforced plastic product obtained by molding the unidirectional aligned prepreg and curing the resin of the molded product is determined by the strength of the cured resin itself and the adhesion between the cured resin and the fibers. However, as mentioned above, the unidirectionally aligned prepreg by the conventional method is determined only by the adhesive force between the cured resin and the fibers, which is relatively weak. It is difficult to take a high value for the strength t in the direction perpendicular to the alignment direction.

In particular, as mentioned above, the strength of products obtained using prepreg with gaps between the fiber bundles decreases, the finish (appearance) is also inferior, and furthermore, there are large variations in product properties. There were other problems. The object of the present invention is to provide an aligned prepreg in which the bonding strength between fibers and resin does not decrease due to mechanical stress and/or thermal changes, and in which gaps are not easily formed between bundles of multifilament fibers, and a method for producing the same. is to provide.

Another object of the present invention is to provide an aligned prepreg whose quality does not deteriorate due to handling, transportation, molding or storage, and a method for manufacturing the same.

Still another object of the present invention is to provide a drawn prepreg that, when used in fiber-reinforced plastic products, can increase the strength of the product in a direction perpendicular to the direction of fiber alignment, and that does not cause variations in other properties. It is in providing the law.

The present inventor completed various researches to achieve the above object, and the characteristics of the aligned prepreg are that a plurality of bundles of multifilament fibers that are parallel in one direction are adjacent to each other, and the bundle of fibers is The filaments are intertwined with other filaments in the direction perpendicular to the fiber axis within and between the bundles, and are impregnated with resin.

The multifilament bundle used in the present invention is a fiber bundle made up of a large number of filaments, and is preferably a yarn or tow made of a bundle of continuous long fibers.

The fibers used in the conventional aligned prepreg are as follows.

(1) Organic fibers: nylon (polyamide-based), rayon (cellulose-based), vinylon (polyvinyl alcohol-based), etc. (2) Organic heat-resistant fibers: aromatic polymers, polybenzimidazole, polyfluorocarbon, polyamide, phenol, polyphenylene Xodiazole, bispenzimidazobenzophenanthroline, polythiadiazole, polyphenylenetriazole, polyvithiazole,
Resin fibers such as polyimide (3) Inorganic fibers: fibers such as glass, boron nitride, alumina, silicon nitride, asbestos, zirconia, silicon carbide, carbon (including carbonaceous, graphite, and flame-resistant materials), (4) Metals Fibers: Fibers of tungsten alloy, helium, copper alloy, iron, aluminum, etc.
5) Composite fibers: fibers such as boron (core wire - tungsten), boron carbide (core wire - tungsten), silicon carbide (core wire - tungsten, boron), etc. (6) (1) - (
A combination of two or more types of fibers shown in 5),
In particular, those with high flexibility and pliability are preferred.

In order to intertwine filaments with other filaments within a multifilament fiber bundle and between that bundle and adjacent bundles, multiple fiber bundles are created so that adjacent bundles overlap each other and the thickness is uneven. Make it into a sheet or tape of a certain width by tightly adhering it so that it does not become loose, and keeping it stretched appropriately so that each bundle does not loosen during processing and disturb the arrangement (
For example, 0.02~0.65f! A tension of /d is applied in the fiber length direction.

), can be obtained by applying a mechanical shock by spraying a high-pressure fluid onto the surface of these textured fibers. High-pressure fluids used at this time include water, mixtures of water and air, organic solvents (e.g. methyl alcohol, ethyl alcohol,
acetone, toluene, methyl ethyl ketone, etc.) and synthetic resins.

When a synthetic resin is used, it is preferably the same as the synthetic resin used to impregnate the fibers, and the viscosity can be lowered by heating it during spraying, or by adding an organic solvent that is compatible with the synthetic resin to be used. Furthermore, diluents other than organic solvents (e.g. plasticizers for vinyl chloride resins, high boiling point solvents,
It is preferable to lower the viscosity of the fluid and spray it using polypropylene glycol, styrene monomer, polyethylene). When water or a mixture of water and air is used as the fluid, the cost of the fluid is low, no adjustment of the fluid is required, the working environment is good, there is no environmental pollution, and the operation and equipment are simple. On the other hand, when organic solvents or synthetic resins are used, the drying process after spraying the fluid is simple or is not necessary at all, and the resin for the matrix is continuously impregnated following the spraying process. be able to.

In particular, when a sufficient amount of synthetic resin is sprayed, the interior of the fiber bundle can be impregnated with the resin by simply rolling the sprayed material without immersing the fibers in the resin again. In order to spray high-pressure fluid onto the fiber bundle surface, a method is adopted in which the fluid is sprayed from nozzle holes provided at appropriate intervals on the fiber bundle surface at right angles to the direction in which the fibers are aligned. The diameter of the nozzle hole, the distance to the fiber, and the number of nozzles vary depending on the thickness of the filament and the thickness of the fiber layer, but the nozzle hole diameter is 1 mm or less, especially 0.5 to 0.
．． 05ml is preferable, but if it becomes too thick, a large amount of filaments will dislocate and become entangled at the same time, making the fiber bundle likely to become disordered, resulting in uneven thickness, and the effect of aligning the fibers being lost.

The distance between the nozzle hole and the fiber bundle surface is determined by the pressure of the high-pressure fluid, the relative movement speed of the fiber with respect to the nozzle hole, the thickness of the fiber filament, the thickness of the bundle, etc., but 1 to 15 strokes is a rough guide. .

The pressure of the high-pressure fluid is also limited by the thickness of the nozzle hole, the distance between the nozzle hole and the fiber bundle surface, the relative movement speed of the fiber with respect to the nozzle hole, the thickness of the filament, the thickness of the fiber bundle, etc. Preferably it is 400 kg/Cd.

If the pressure is less than 50k9/d, there will be little dislocation of the filaments and the engagement between the fiber bundles will be insufficient, and
When 001<9/d is exceeded, the filament is frequently broken and fluff becomes severe. When spraying high-pressure fluid onto the fiber bundle surface, the nozzle may be fixed and moved in the direction in which the fiber bundles are aligned, and may also be moved in a direction perpendicular to that direction, or vice versa. may be fixed.

The moving speed of the nozzle or fiber bundle is suitably about 1 to 10 m/Mm. When processing a fiber bundle continuously, as shown in Figure 2, the fiber bundle is wound up under endless tension, and at the same time, the fiber bundle is reciprocated in a direction perpendicular to the winding direction. This is done by injecting pressurized fluid. The resins used for impregnation include thermosetting resins such as phenolic resins, unsaturated polyester resins, and epoxy resins, and heat-resistant resins such as polyimide resins, polybenzimidazole resins, polyphenylene resins, and Friedel-Crafts resins. In order to reduce the viscosity, it is heated or an organic solvent and/or diluent is added thereto.

Furthermore, when spraying high-pressure fluid onto the fiber bundle surface, a patch plate is provided close to the back surface of the fiber bundle surface onto which the high-pressure fluid is sprayed, and parallel to the fiber bundle surface. Furthermore, if the high-pressure fluid is bounced once and collided with the fiber bundle again, the transfer of the filaments will be carried out efficiently.
The caul plate has a substantially smooth surface that can reflect fluid, and is made of metal, plastic, glass, wood, hard rubber, or the like.

The structure used is a flat plate or cylinder having no holes at all, or a structure having holes in the shape of a mesh, a lattice, or a strip as shown in FIGS. 3 to 6. When using a backing plate, the fiber bundles are arranged on top of the backing plate, and since this backing plate is used, it is easy to attach the restrainer for the fiber bundle, and it is easy to apply tension to the fibers, so the degree of entanglement of the filaments can be adjusted freely. Can be adjusted.

Next, one embodiment of the method for manufacturing aligned prepregs of the present invention will be described with reference to the drawings.

In FIGS. 1 and 2, the multifilament bundle 1 drawn from the creel 7 is wound up by the winding drum 14, and the multifilament bundle group 1 is held down and passed through the tray 9 by rollers 41, 42, and 43. , during the passage of the multifilament bundle, a pump 8 pumps high-pressure fluid through a nozzle hole 6 provided at right angles to the direction of movement of the multifilament bundle and at an appropriate distance from the multifilament bundle surface. Spray on.

The tray 9 is a container for storing the fluid sprayed onto the fiber bundle between the holding rollers 42 and 43. Although not shown in the figure, the tray 9 is provided with a fluid outlet, and the fluid can be discharged as needed. It is returned to the high pressure pump 8 and used for circulation. In addition, a patch plate 3 is provided in the receiving tray 9 in parallel with the transition surface of the fiber bundle, and the high-pressure fluid that has been blown onto the fiber bundle is applied to this plate and is bounced back to the filament of the fibers to arrange it. Use efficiently. The caul plate reflects high pressure fluid,
In this embodiment, as shown in FIGS. 3 to 6, a large number of holes are provided in the flat plate, including a flat plate and a cylindrical shape, so that the high-pressure fluid flows through the bundle of fibers. The filament of the fiber can be easily passed through the fiber not only in the lateral direction, but also in the lateral direction.
It is also possible to arrange the filaments of the fibers in the thickness direction of the fiber bundle to entangle them.

That is, FIG. 3 shows a flat patch plate 3a, FIG. 4 shows a flat patch plate 3b with strip-shaped holes 5b, and FIG. 5 shows a flat patch plate 3c with a mesh-shaped patch. FIG. 6 shows a plan view of a cylindrical patch plate 3 provided with a hole 5c.
d is used to spray high-pressure fluid from a nozzle 6d onto a fiber bundle 1d.

The caul plate provided with this hole is suitable for manufacturing thick prepreg. Further, in FIGS. 1 and 2, 6 is a nozzle which is caused to reciprocate at right angles to the direction in which the fiber bundle moves.

A bundle of fibers in which the filaments are dislocated in a direction perpendicular to the fiber axis by high-pressure fluid and become entwined to form a sheet is transferred to the drying oven 10 as needed, where it is dried, and then the bundle of fibers is is placed in the resin impregnation tank 11 and immersed in the resin bath therein. Next, the resin is sufficiently impregnated by the roller 12, and the amount of resin impregnated is adjusted. Further, if necessary, the fibers are placed in a heating furnace 13 to volatilize the organic solvent component contained in the resin-impregnated fibers, and to increase the degree of polycondensation of the resin.Finally, a rolled prepreg is obtained by a winder 14. It is preferable that the molded body heated in the heating furnace 13 be sandwiched with release paper. As shown in FIG. 7, the aligned prepreg of the present invention has a part or most of the filaments 2e dislocated and entangled between the fiber bundles 1e and within the bundles. Therefore, unlike the conventional product shown in Figure 8, the binding strength between the fibers and the resin does not decrease due to mechanical stress and thermal stress, and as a result, no gaps are created between the fiber bundles. Therefore, the quality does not deteriorate due to handling, transportation, processing, or storage.

Furthermore, when this is used to make fiber-reinforced plastic products, there is almost no decrease in strength in the longitudinal direction of the fibers, and the strength in the direction perpendicular to the fiber alignment direction is 1.5 to 4% compared to products obtained by conventional methods. It can even be increased by a factor of two. Next, embodiments of the present invention will be described with reference to Examples, but the present invention is not limited thereto.

Example 112000 filament, 4800 denier carbon fiber (tensile strength 340 kg/Md, tensile modulus 2
100 filament yarns of 0t/Md) were lined up on a wooden plate under a tension of 0.109/d, and a dinit flow of water was applied over the lined yarns under the following conditions. I sprayed it.

Conditions for dinit flow of water Nozzle diameter 0.2mmφ Pressure Max2OOl<9/Cd (pulsating flow 40 times/min) Distance between nozzle tip and yarn 3m/m Number of nozzles 1 Nozzle moving speed 4.5m/Ttul (It moved in the direction perpendicular to the alignment direction and was sprayed over the entire surface at a width of 5 m/m.) After the process of spraying the dinit flow of water, a part of the treated carbon fiber was taken and its properties were measured. No decrease was observed in the tensile strength or tensile modulus compared to before the process.

The interbundle breaking strength in the direction perpendicular to the fiber length was 0 before the spraying process, but 200 after the spraying process.
9/1? It became thicker.

After drying the sheet thus obtained at 100°C for 2 hours, an epoxy resin using methyl ethyl ketone as a solvent (Epicoat◆828, 100 parts BF3MEA3PHR,.M
EKl5OPHR) and then dried at 120° C. for 15 minutes.

These 0.1 mm thick aligned prepreg sheets were laminated in one direction and molded into a size of 150 x 80 x 3 mm. At this time, the tensile strength in the fiber direction (σy) is 193 kg/Md
Tensile strength (σx) perpendicular to l fiber is 8.4 kg/Md
It was hot. The fiber volume content at this time was 61%.
Example 2 The pressure of the dinit flow of water is 400 kg/C! An aligned prepreg sheet was obtained by treating carbon fibers under the same conditions as in Example 1 except that the carbon fiber was changed to 1.

These were laminated according to Example 1 and molded to the same size as in Example 1. σy of this is 1891<9/M7
l. , σx was 14.1 kg/M7l.

Example 3 Carbon was produced under the same conditions as in Example 1, except that a dinit stream was sprayed using a solution containing 35% epoxy resin in methyl el ketone (also containing a hardening agent, viscosity 25σp at 20°C) instead of water. The fibers were processed to obtain a bow-aligned prepreg sheet.

These were laminated according to Example 1 and molded to the same dimensions as the molded product of Example 1. The σy of this item is 194kg/Md
lσx was 7.6 kg/Md. Comparative Example 1 The carbon fibers used in Example 1 were treated under the same conditions as Example 1 except that the dinit flow of water was not used, and the obtained aligned prepreg sheet was further laminated according to Example 1. It was molded to the same dimensions as the molded product of Example 1.

σy of this is 1951<9/MiLlσx is 3.8
kg/M7jI.

[Brief explanation of drawings]

Fig. 1 is a process explanatory diagram of one embodiment of the method for producing aligned prepregs of the present invention, Fig. 2 is a perspective view of an apparatus for spraying high-pressure fluid onto fiber bundles, and Figs. 3 to 5 show various types of FIG. 6 is a front view of a device that uses a cylindrical patch plate to spray high-pressure fluid from a nozzle onto a fiber bundle, and FIG. 7 is a longitudinal cross-sectional view of the aligned prepreg of the present invention. FIG. 8 shows a longitudinal sectional view of a conventional aligned prepreg. 1, 1e, 1f: bundle, 2e, 2f: filament, 3,
3a, 3b, 3c, 3d: patch plate, 41, 42, 43:
Holding roller, 5b, 5c: hole, 6, 6d: nozzle, 7
Rita reel, 8: high pressure pump, 9: saucer, 10: drying oven, 11: impregnation tank, 12: roller, 13: heating furnace, 14
: Winder.

Claims (1)

[Claims] 1. A plurality of bundles of multifilament fibers arranged in parallel in one direction are adjacent to each other, and in the fiber length direction, between and within these bundles, some or most of the filaments are other filaments. A prepreg made of fibers that are entangled with each other and impregnated with resin. 2 A plurality of multifilament fiber bundles are placed adjacent to each other in parallel in one direction, and a high-pressure fluid is sprayed onto the resulting fiber bundle assembly, and a resin is applied to the fiber bundle assembly during or after the spraying. A method for producing aligned prepreg characterized by impregnation. 3. The method for producing aligned prepreg according to claim 2, wherein the fluid is water, a mixture of water and air, an organic solvent, or a synthetic resin. 4. The method for producing aligned prepreg according to claim 2 or 3, wherein the pressure of the fluid is 50 to 500 kg/cm^2. 5 A plurality of multifilament fiber bundles are placed in parallel in one direction and adjacent to each other, and while the resulting fiber bundle assembly is continuously wound, a direction perpendicular to the moving direction of the fiber bundle is High-pressure fluid is sprayed from a nozzle that ejects high-pressure fluid reciprocating in the direction onto the aggregate of the fiber bundles, and between the fiber bundles and within the bundles, part or most of the filaments are transferred to other fibers. A method for producing aligned prepreg, which comprises entangling the fibers with filaments and impregnating the assembly of fiber bundles with a resin during or after spraying with the high-pressure fluid. 6. The method for producing aligned prepregs according to claim 5, wherein the fluid is water, a mixture of water and air, an organic solvent, or a synthetic resin. 7. The method for producing aligned prepreg according to claim 5 or 6, wherein the pressure of the fluid is 50 to 500 kg/cm^2.