JPH03236943A - Composite molded product composed of prepreg and molding material - Google Patents

Abstract

PURPOSE:To provide strength and good appearance by using a prepreg composed of resin and high strength fiber and molding the outside of prepreg by means of SMC, BMC or premix or the like in a mold. CONSTITUTION:A prepreg 1 composed of high strength fiber and a molding material such as SMC, BMC 2 or dry premix composed of a base of same family of said prepreg and resin is fed into a mold and molded integrally. As for the high strength fiber to be used, a fiber having tension strength, which is the tensile strength divided by density, 10X10<8>cm or more is used. At that time, the content should be 5 - 50% (wt.%), preferably 8 - 25%. The prepreg is prepared by applying resin to high strength fiber for impregnation or coating. On the other hand, the fiber content of molding material such as SMC, BMC, dry premix or the like composed of the same base and resin should be 5 - 50%, preferably 20 - 35%. The prepreg thus prepared is charged to a section where the strength in a molded product is required. Then, the molding material such as SMC, BMC or dry premix is filled, heated and pressurized therein to manufacture a composite molded product.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a process in which a prepreg made of high-strength fiber and a molding material such as SMC or BMC made of the same type of resin and base material are put into a mold and integrated. High strength and good moldability are obtained by molding, using prepreg in parts that require strength, and using molding materials such as SMC or BMC in parts that do not require as much strength. This invention relates to a low-cost composite molded product.

(Prior Art) Conventionally, prepregs made of high-strength fibers generally have a very high base material content (usually 70% by weight or more) to increase impact resistance.

Therefore, the appearance of the obtained molded product was not very good. On the other hand, molding materials such as SMC and BMC have relatively short fiber lengths and generally have a low content (20 to 50% by weight), and in particular during molding, because fibers and resin flow simultaneously in the mold,
The appearance of the molded product was smooth and good. Therefore, a part of the molded product (for example, the inner surface) requires great strength, and it is very difficult to obtain a molded product with a good appearance using only one type of material.

(Object of the invention) The present invention uses a prepreg made of resin and high-strength fibers in the inside (or outside) of a molded product where high strength is required for functionality, and the outside (or inside) has a good appearance. Obtained S
By using a molding material made of the same type of resin and base material such as MC, BMC or dry pre-coated wood, and molding them simultaneously in a mold, the inside (or outside) can withstand high strength and the outside (or inside) A composite molded product with a good surface appearance has been completed.

(Structure of the Invention) The present invention involves integrally molding prepreg made of high-strength fibers and molding materials such as SMC, BMC, and dry braking made from the same base materials and resins in a mold. The present invention relates to a composite molded article characterized by: The high-strength fibers used in the present invention have a specific tensile strength calculated by dividing tensile strength by density of 10 x 10 6 cm or more, and a specific elastic modulus calculated by dividing elastic modulus by density of 2.5 x 10 11 cm or more. Specifically, carbon fibers, aramid fibers, high-strength glass fibers, aromatic polyester fibers, high-strength polyethylene fibers, vinylon fibers, cera-smelling ivy fibers, etc. are used. General glass fibers, nylon fibers, polyester fibers, etc. are not applicable.

The resin to be impregnated into these high-strength fibers is preferably a thermosetting resin such as a phenol resin, an epoxy resin, a polyurethane resin, an unsaturated polyester resin, a vinyl ester resin, a polyamide resin, or a maleimide resin.

Prepreg is obtained by impregnating or coating high strength fibers with resin. At this time, the resin content is 5 to 50% (
(wt%), preferably 8 to 25%. 5%
It is difficult to make a uniform prepreg under 5
If it exceeds 0%, the required strength cannot be obtained.

On the other hand, in the case of molding materials such as SMC, BMC, and dry premix, which are made from the same base material and resin, the fiber content is 5 to 5.
50%, preferably 20-35%. If it is less than 5%, it is difficult to obtain this material, and if it is more than 50%, a molded product with good appearance cannot be obtained.

The prepreg thus obtained hedges parts of the molded product that require strength. Next, a molding material such as SMCBMC or dry premix is filled, heated and pressurized to create a composite molded product.

Alternatively, the steps may be performed in the reverse order. Another method is to sandwich and mold the prepreg between the molding materials in the form of a sandwich.

The molded product made according to the present invention uses high-strength fibers in areas that require strength on the inner surface (or inside or outside), so it can withstand impact forces, etc. SMC, BMC, etc. are used for the inner surface), so it has a good surface appearance, and prepreg and SMC, BMC
The contact surfaces of the two are made of the same material and resin, so they are in very strong contact (joint). Therefore,
According to the conventional approach, it was difficult to obtain a molded product with good appearance and high strength by simultaneous molding, but the present invention solves this problem.

Note that a composite molded product may be obtained by molding a high-strength prepreg in advance, inserting it into a mold, and molding it with SMC, BMC, or the like. In this case, it is preferable that the appearance of the prepreg molded product is uneven, and the adhesion (joint) at the boundary between the SMC and 8MC molded products becomes stronger. The general method for manufacturing prepreg is to impregnate it with resin and then dry it with hot air, but for cylindrical prepregs, a cylindrical mold is prepared in advance to match the product shape (the outer surface of the cylinder is It is also possible to obtain a cylindrical prepreg by winding the prepreg (which may have an uneven or screw-like shape) using a filament winding (FW) method. At this time, the resin may be dried before the impregnated yarn is wound with the FW, or after the yarn is wound, it may be placed in a suitable furnace. The obtained cylindrical prepreg may be cut into approximately 2 to 6 pieces in the axial direction to fit the mold.

(Example) The present invention will be explained below using examples.

Example 1 Specific tensile strength 19X106CTI+, specific modulus 17.2X
Woven fabric made of 101 Icm carbon fiber (thickness 0.2
5mm, basis weight 200g/rd) with bisphenol A
The mold was impregnated with epoxy citrus and dried to obtain a prepreg with a resin content of approximately 18%. On the other hand, a BMC with a carbon content of 25% was obtained using a 3-inch roving of the above carbon fiber, an epoxy resin, a filler, a catalyst, a mold release agent, and the like. Fill a semi-cylindrical mold with BMC (2), then charge five sheets of the prepreg (1), clamp the mold, heat and pressurize to form a composite molded product with a thickness of about 6 mm as shown in Fig. 1. I got it.

Comparative Example 1 An appropriate amount of the above BMC alone was filled into a mold and hot-pressed to obtain a molded product having the same shape as in Example 1.

Example 2 Specific tensile strength 1.6X106 mark, specific modulus 3.2 XIO
'cm woven fabric (thickness 0.2 cm) made of high strength glass fiber
3 mm, basis weight 150 g/nf) was impregnated with a resol type phenolic resin and dried to obtain a prepreg with a resin content of 20%.

On the other hand, a phenol SMC having a glass content of about 30% was prepared using a 1-inch roving of the above fibers, a resol-type phenolic resin, a filler, a catalyst, a thickener, a mold release agent, and the like.

First, phenol SMC (
Charge one layer of sheet 3), stack 8 sheets of prepreg (4) above, and then add phenol S on top of it.
Four layers of M C (5) were stacked, and after mold clamping, hot pressure pressing was performed to obtain a composite molded product having a shape shown in FIG. 2 and having a thickness of about 6 mm.

Comparative Example 2 Six layers of the above-mentioned SMC were stacked together and hot-press pressed. Example 2
A molded article having the same shape as that was obtained.

Example 3 Specific tensile strength 21 x 106 cm, specific modulus of elasticity 6.4 Xl0
Woven fabric made of 8cm ARA5D fiber (thickness 0.45na)
++, basis weight 460 g/nf) was impregnated with a vinyl ester type unsaturated polyester resin and dried to obtain a prepreg with a resin content of approximately 15%.

On the other hand, BMC with an aramid content of about 25% was obtained by chopping the above-mentioned aragodo fiber to about 1/16 inch, isofucric acid-based polyester resin, filler, catalyst, mold release agent, etc. Ta.

In order to obtain a molded product with the shape shown in Fig. 3, first B
MC (7) was uniformly charged in a mold, six layers of the above prepreg (6) were placed on top of it, and hot pressure pressed to form a BMC layer with a thickness of about 3.5 mm and a prepreg layer with a thickness of about 2.5 mm.
m thick, has high-strength uneven parts, and has a smooth opposite surface.
A composite molded article having the shape shown in the figure was obtained.

Comparative Example 3 Using only the BMC of Example 3, hot pressing was carried out to produce Example 3.
A molded article having the same shape as that was obtained.

For composite molded products on each side, JIS T 81
An impact resistance (penetration resistance; drop of a 3 kg steel striker from a height of 50 cm) test was conducted in accordance with No. 33, and the depth of the fractured dent was measured using calipers. , and the falling positions are shown in FIGS. 1, 2, and 3, respectively.

The results are shown in Table 1.

Table 1 (Effects of the Invention) The composite molded product of the present invention has significantly improved impact resistance by using a high-strength prepreg.

In order to further improve the impact resistance, it is possible to mold a molded product using only high-strength prepreg, but the cost will increase significantly (more than double) and the appearance will be poor due to the low resin content. It deteriorates and has no merit as a product.

[Brief explanation of drawings]

FIGS. 1 to 3 are perspective views showing examples of the structure of the composite molded product of the present invention. In each figure, the dotted arrow indicates the drop position during the drop test.

Claims (1)

[Claims] (1) Composite molding characterized by integrally molding a prepreg in which resin is impregnated or applied to high-strength fibers, and molding materials such as SMC, BMC, and dry premix made of the same type of resin and base material. thing.