JP4723270B2 - Method for forming container using flame retardant hybrid composite material - Google Patents

Description

The present invention relates to a method for molding of superior made of FRP container flame retardancy using the flame retardant hybrid composite.

Fiber Reinforced Plastic (FRP) is a thermosetting resin such as unsaturated polyester resin, epoxy resin, polyimide resin, matrix resin of thermoplastic resin such as polyethylene, polypropylene, polyamide, PPS, PEEK, carbon fiber, glass fiber Since it is made of fiber reinforcement such as aramid fiber and is lightweight and excellent in strength properties, it has been used in a wide range of fields from the aerospace field, transportation / transport field to general industrial field in recent years.

When molding an FRP product, a prepreg, which is a sheet-shaped molding intermediate in which a fiber reinforcing material is impregnated with a resin and is easy to handle except for fluidity and adhesiveness, is often used. And as a method for shape | molding a hollow member using a prepreg, the autoclave molding method, the hot press molding method, the vacuum bag molding method, etc. are known.

Among fiber reinforcements, carbon fiber is lightweight and is increasingly used in the aerospace field, transportation / transportation field, but FRP using carbon fiber is excellent in heat resistance, but the carbon fiber itself Burns at high temperatures in air. Therefore, it is necessary to improve and improve flame retardancy depending on the application.

On the other hand, various performances have been improved and improved by combining two or more kinds of fiber reinforcements into a hybrid composite material. For example, it is known that when glass fiber, carbon fiber, and aramid fiber are appropriately combined, the strength and elastic modulus of the laminate are increased depending on the type of combination (see Non-Patent Document 1). In addition, a lightweight high-pressure gas container using a hybrid composite material of glass fiber and carbon fiber (see Patent Document 1) or a flame-retardant imparting particle that produces a glassy ceramic by heating is dispersed in a polymer material such as a resin. A flame retardant polymer composite material obtained by coating is also known (see Patent Document 2).
Morio Naoo, “Plastic Advanced Composites” Polymer Publications, published October 5, 1998, pages 142-145 Japanese National Patent Publication No. 8-510428 JP 2001-131431 A

However, it has not been proposed so far to use specific hybrid composites and combinations of these specific laminates to impart flame retardancy to FRP containers for specific uses.

An object of the present invention is to provide an inexpensive method of forming containers having excellent flame retardancy with hybrid composite material showing a high flame retardancy.

According to the first aspect of the present invention, a prepreg of glass fiber cloth is laid along a carbon steel main mold that forms the outer surface of a container, and a prepreg of unidirectionally arranged carbon fibers is placed on the prepreg. Then, or after further placing a prepreg of glass fiber cloth on top of each other, an aluminum alloy insert forming the inner surface of the container is inserted and arranged inside the main mold, and is heat-molded. This is a method for forming a hollow container made of FRP having an open surface with excellent flame retardancy.

According to the present invention, excellent flame retardancy, light weight containers with flame retardant hybrid composite having excellent flame retardancy to pass in particular vertical burning test it can be manufactured in a relatively inexpensive manner. And the obtained container is utilized as a FRP molded product of various uses, or its member.

The flame-retardant hybrid composite material of the present invention comprises a prepreg of unidirectionally arranged carbon fibers and a prepreg of glass fiber cloth that is laminated on one or both sides thereof. Although carbon fiber itself burns in high-temperature air, it is inherently quite flame retardant, so, for example, only carbon fiber prepreg passes the horizontal combustion test sufficiently. However, there is a problem that the vertical combustion test, which seems to be more severe as a combustion condition, fails. The present inventor has found that a composite material that passes the vertical combustion test can be obtained by combining a carbon fiber prepreg and a glass fiber prepreg while maintaining the lightness of the hybrid composite material as much as possible. I found it.

In the container of the present invention, at least a part of the outer surface of the container wall is formed from a prepreg of glass fiber cloth, and at least a part of the inner layer of the container wall is formed from a prepreg of unidirectionally arranged carbon fibers, Is a container excellent in flame retardancy in which at least a part of is formed from a prepreg of unidirectionally arranged carbon fibers or a prepreg of glass fiber cloth. When the container is, for example, a bowl-shaped rectangular parallelepiped, all the wall surfaces are formed of a prepreg of a glass fiber cloth on the outer surface, and a prepreg of a unidirectionally arranged carbon fiber or a prepreg of a glass fiber cloth on the inner surface. However, when the flame retardancy requirement varies depending on the use conditions and use mode of the container, only the wall surface that requires flame retardance is used with the flame retardant hybrid composite material of the present invention. It may be formed. For example, in the case of a cylindrical container, the cylindrical wall surface is formed of the flame-retardant hybrid composite material of the present invention (the outer surface is a glass fiber cloth prepreg), and the bottom surface is formed only of a carbon fiber prepreg. Also good.

Further, the present inventor does not simply combine the prepreg of carbon fiber and the prepreg of glass fiber, but arranges the prepreg of glass fiber cloth on the outer surface of the wall of the container, so that the inner layer of the wall, that is, the inside is unidirectional. By arranging a carbon fiber prepreg and arranging a unidirectional carbon fiber prepreg or a glass fiber cloth prepreg on the inner surface of the wall, a lightweight and excellent flame-retardant container is formed for the first time. We have found that this is possible and have also completed the present invention relating to containers.

By placing a glass fiber cloth prepreg on at least the outer surface of the container wall, burrs are formed when the molded product is further processed, i.e., for example, when the end of the molded product is perforated. The phenomenon of FRP peeling off can be suppressed. In addition, by disposing a prepreg of unidirectionally arranged carbon fibers in at least the inner layer, the mechanical properties required particularly for the container are satisfied.

In the container of the present invention, a prepreg of glass fiber cloth is laid along the main mold forming the outer surface of the container, and the prepreg of the unidirectionally arranged carbon fiber is arranged on the prepreg, and thereafter or further glass After placing the fiber cloth prepregs on top of each other, insert and place the insert that forms the inner surface of the container inside the main mold, and then clamp the mold consisting of the main mold and the insert and heat It is obtained by molding and die-cutting after cooling. Each prepreg may be used as a single layer or a plurality of layers. The heat forming is suitably performed, for example, at 100 to 130 ° C. for 1 to 2 hours in a curing furnace or an autoclave.

The prepreg of the present invention is a prepreg obtained by impregnating a fiber reinforcement made of glass fiber cloth or unidirectional carbon fibers with a matrix resin such as a thermosetting resin or a thermoplastic resin. The glass fiber cloth means a fabric such as a woven fabric or a non-woven fabric made of glass fiber, and a woven fabric such as plain weave or twill weave is preferable. A unidirectional carbon fiber means a state in which carbon fiber strands (fiber bundles) are aligned in one direction, and the strands are aligned in one direction to form a sheet, which is stitched in a perpendicular direction. And a multiaxial fabric in which a plurality of sheet-like materials aligned in one direction are stacked at different angles and stitched with stitch threads in a perpendicular direction. The basis weight is preferably 100 to 300 g / m ^{2 in} the case of a prepreg using a glass fiber cloth, and is preferably 100 to 300 g / m ² also in the case of a prepreg using unidirectionally arranged carbon fibers.

Preferred as the matrix resin are thermosetting resins, such as epoxy resins, unsaturated polyester resins, phenol resins, melamine resins, polyurethane resins, silicone resins, maleimide resins, vinyl ester resins, cyanate ester resins, maleimide resins and cyanide resins. Examples thereof include a resin obtained by prepolymerizing an acid ester resin. These thermosetting resins may be blended in appropriate amounts. Of these resins, epoxy resin compositions and vinyl ester resin compositions excellent in heat resistance, elastic modulus, and chemical resistance are particularly preferable. These thermosetting resins may contain a curing agent, a curing accelerator and the like. The ratio of the fiber reinforcing material to the matrix resin is preferably 30 to 70% by weight of the total fiber reinforcing material.

An example of a container obtained with this onset bright, described drawings. FIG. 1 shows a hollow rectangular parallelepiped made of FRP having an open surface, that is, a bowl-shaped container used for an engine cover or the like.
The outer surface 1 of the front and back surfaces of the container is formed from a prepreg of glass fiber cloth, and the inner surface 2 is formed of a prepreg of unidirectionally arranged carbon fibers. In FIG. 1, it is the part which the upper surface is opening, and here, it can process variously according to a use, or can install various components, for example, a flange and other insert components. Moreover, a bolt hole can also be provided in the wall surface of a rectangular parallelepiped as needed, for example. And installation of a flange and other insert parts, drilling of a baltic hole, etc. may be performed after shape | molding a rectangular parallelepiped, or may be performed simultaneously with shaping | molding. Or you may shape | mold the thing which the flange is attached to the opening part of the hollow rectangular parallelepiped of FIG. 1 by integral molding.

It will be described with reference to FIG. About inventions according to claim 1 of the present invention. FIG. 2 shows a cross-sectional view of a mold when a hollow rectangular parallelepiped having a flange attached to the opening is formed. In FIG. 2, 5 is the lower mold of the main mold, 6 is the upper mold, and 7 is the insert. FIG. 2 shows a case where a hollow rectangular parallelepiped 9 (a prepreg made of a flame-retardant hybrid composite material) having a flange attached to the opening is formed. Therefore, the insert 7 has a T-shaped cross section. Reference numeral 8 denotes an auxiliary mold made of a rubber substrate. First, a prepreg of a glass fiber cloth is laid along the inner wall of the lower mold 5 of the main mold, and the prepreg of the unidirectionally arranged carbon fiber is arranged thereon, and then the insert 7 is inserted and arranged. In some cases, a prepreg of glass fiber cloth may be further disposed on the prepreg of unidirectionally arranged carbon fibers. Then, the upper mold of the main mold is placed on the T-shaped upper surface of the insert 7 via the rubber substrate 8, and the mold is clamped. The mold clamped is placed in, for example, a curing furnace and heated at 90 to 180 ° C. for 1 to 2 hours. Due to the difference in thermal expansion pressure between the main molds 5 and 6 and the insert 7 due to heating, the expansion pressure of the auxiliary rubber substrate 8 is further applied, so that the prepreg 9 made of a flame retardant hybrid composite material is strongly against the inner wall of the lower mold. It cures in the pressed state. Then, after cooling the mold, the rectangular parallelepiped 9 that is a molded product can be easily released from the mold and taken out.

Square shape will be explained further formed form process containers (one surface rectangular hollow steel FRP which is open) by reference. As shown in FIG. 1 , flame retardant hybrid composite materials are used for the front and back surfaces of the rectangular parallelepiped, and the rectangular parallelepiped is cut into strips in the thickness direction of the rectangular parallelepiped. The object is to form a container in which small pieces of carbon fiber prepreg are laminated to a desired thickness. First, as shown in FIG. 3, two members having a shape in which the rectangular parallelepiped of FIG. In FIG. 3, the outer surface 1 of the front surface or the back surface is a prepreg of glass fiber cloth, and the inner surface 2 is made of a prepreg of unidirectionally arranged carbon fibers. Small pieces 3 and 4 of carbon fiber prepreg are laminated and arranged in a desired thickness at three ends of the front surface or the back surface. Two members having a concave horizontal cross-section with such a surface contrast are formed, then the obtained members are combined with each other in a surface contrast, and the laminated portion of the laminated prepreg pieces is bonded with adhesive or bolting or the like. Join to form a hollow cuboid.

At this time, if a fiber reinforced resin sheet is disposed on at least one side of the lamination surface of the small pieces of carbon fiber prepreg so as to cover the lamination end surface, the denseness of the container is increased and liquid leakage and the like can be prevented. is there. For molding the member, an autoclave molding method or a vacuum bag molding method can be adopted, but the autoclave molding method is preferred. The heating temperature for autoclave molding is suitably from 80 to 200 ° C., and the pressing pressure is suitably from 0.05 to 4 MPa. The fiber reinforced resin sheet used to increase the density of the container is impregnated with a thermosetting resin or a thermoplastic resin into a woven or nonwoven fabric such as glass fiber, carbon fiber or aramid fiber. It means the obtained prepreg. Preferred is a glass fiber prepreg. The fiber reinforced resin sheet is used by cutting into a size covering the left and right surfaces and the bottom surface according to the shape of the rectangular parallelepiped. The basis weight of the fiber reinforced resin sheet is not particularly limited. For example, in the case of a prepreg using a glass fiber cloth, 100 to 300 g / m ² is preferable.

Hereinafter, the present invention will be described in detail by way of examples. The flame retardancy was evaluated according to the following combustion test method.
[Combustion test]
According to UL94 as flame retardant certification standard. As a test sample, a specimen having a width of 13 ± 50.5 × a length of 125 ± 5 mm cut from the hybrid composite material of the present invention or a carbon fiber prepreg having the same thickness was used. In the horizontal combustion test (UL94 HB), a sample is fixed at one end and held horizontally, and a gas burner flame is brought into contact with the free end for 30 seconds. If the sample continues to burn after releasing the flame, the rate of combustion is measured. A sample having a thickness of 3.05 mm or more is considered acceptable if the burning rate does not exceed 38.1 mm per minute and combustion stops before the flame reaches the point of 102 mm from the end of the sample. In the vertical combustion test (UL94 V-0), a gas burner flame is brought into contact with the lower end of the sample held vertically for 10 seconds. If the combustion stops within 30 seconds, indirect flame for another 10 seconds. Then, after any flame contact, if it satisfies the criteria such as not continuing the combustion for 10 seconds or more, not burning to the position of the fixing clamp, or not dropping the combustion particles that ignite the absorbent cotton, it is determined to pass.

[ Reference Example 1 ]
The example which manufactured the rectangular parallelepiped as shown in FIG. 1 is shown. The front and back walls of the container are 170 x 1065 cm in length and breadth, and both surfaces are impregnated with glass fiber fabric (weight per unit: 200 g / m ² , WE18K, manufactured by Nittobo) with epoxy resin (resin content 38%) One prepreg is arranged, and the inner layer is a laminate of 11 unidirectionally arranged carbon fiber prepregs (high elastic prepreg, fiber content = 60%, manufactured by Toho Tenax Co., Ltd.), and the inner surface is One prepreg of the same glass fiber fabric as described above is arranged to constitute one wall (hybrid composite material). On the left and right surfaces, 33 pieces of the same unidirectionally arranged carbon fiber prepreg as above were cut into strips of 160 × 10.5 cm in length and width. On the bottom surface, 33 sheets of the same prepreg cut into strips of 10.5 × 1065 cm are stacked.

A specific molding method is as follows. 33 strips of 160 × 10.5 cm long and horizontal prepregs are stacked on both ends of the short side of a hybrid composite material (prepreg) of 170 × 1065 cm in length and width, and 10.5 × 1065 cm in length and width in the form of strips at one end of the long side. 33 prepregs were laminated to form a molding member having a concave horizontal cross section. Another member of the same type was prepared, and these two members having a concave horizontal section were autoclaved under pressure of 0.5 MPa and 120 ° C. for 2 hours. The two members thus obtained were combined for surface control, and the laminated portions of the laminated prepreg pieces were joined by bolting to form a hollow rectangular parallelepiped.

When the combustion test of the hybrid composite material constituting the surface was conducted, it passed both the horizontal combustion test and the vertical test.

[ Reference Example 2 ]
Along with the main mold (split mold) of the mold that forms the outer surface of the bowl-shaped container, first, a prepreg of a glass fiber cloth is laid, and then a prepreg of a unidirectionally arranged carbon fiber is placed on the prepreg, As in Reference Example 1 , carbon fiber prepreg pieces are stacked on the left and right surfaces and the bottom surface, and then inserts that form the inner surface of the container are inserted and arranged inside the main mold, and the mold is clamped. Then, heat molding was performed under the same conditions as in Reference Example 1 . Thereafter, the mold was cooled, and the molded product was released to obtain a bowl-shaped container.

When the combustion test of the hybrid composite material constituting the surface was conducted, it passed both the horizontal combustion test and the vertical test.

[Comparative Example 1]
A glass container prepreg was not used, and only a carbon fiber prepreg was used to form a bowl-shaped container in the same manner as in Reference Example 1 . In this case, when a hole was drilled in the wall surface, unlike the case of Reference Example 1 or 2, a phenomenon that a part of the wall surface was peeled off (burring) was observed on the side where the hole was drilled. Moreover, in the result of the combustion test of the prepreg of the carbon fiber used for this, it passed the horizontal combustion test, but failed the vertical combustion test.

[ Example 1 ]
Using a mold whose cross section is shown in FIG. 2, a hollow straight body having a flange attached to the opening was formed. One glass fiber cloth prepreg is laid on the inner surface of the cavity of the lower mold 5 of the main mold made of carbon steel (S45C), and 11 unidirectionally-arranged carbon fiber prepregs are stacked on the prepreg. One glass fiber cloth prepreg was laminated and arranged (hybrid composite material). The same prepreg as in Example 1 was used. Next, an insert 7 made of aluminum alloy (2017) is inserted and arranged in the cavity of the lower mold 5 of the main mold through a prepreg 9 of a hybrid composite material, and further, a rubber substrate is placed on the T-shaped upper surface of the insert 7 The upper mold 6 of the main mold was installed through 8 and the mold was clamped. The clamped mold was placed in a curing furnace and heated at 120 to 130 ° C. for 1.5 hours. After the mold was taken out and cooled, the hollow straight body 9 with the flange attached to the opening could be easily removed from the mold and taken out. The obtained molded product was a hollow rectangular parallelepiped with a flange having a strict squareness.

Since the container of the present invention is excellent in flame retardancy, it can be used for a motor cover such as a linear motor, for example, by forming a flange on the opening surface.

It is explanatory drawing which shows an example of the container of this invention. It is explanatory drawing which shows the shaping | molding method of the container of this invention. It is explanatory drawing which shows another example of the shaping | molding method of the container of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass fiber cloth prepreg 2 Unidirectionally arranged carbon fiber prepreg 3, 4 Small piece of carbon fiber prepreg 5 Lower mold main mold 6 Upper mold main mold 7 Insert 8 Rubber substrate 9 Straight body Or a prepreg made of a flame retardant hybrid composite material

Claims (1)

A glass fiber cloth prepreg is laid along a carbon steel main mold that forms the outer surface of the container, and a unidirectionally arranged carbon fiber prepreg is placed on the prepreg, and then, or further, a glass fiber cloth. After placing the prepregs on top of each other, an aluminum alloy nest that forms the inner surface of the container is inserted and arranged inside the main mold, and is heat-molded. A method for forming an open FRP hollow container.

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