JPH0586967B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a fiber-reinforced resin molded product. (Prior Art) Fiber-reinforced resin molded products made by impregnating fibers with resin are used in various industrial fields because they are lightweight and have high strength. In particular, molded products using glass fibers or carbonate fibers are widely used because of their excellent strength and rigidity. (Problems to be Solved by the Invention) However, when these molded products are put into practical use and subjected to impact, those using carbon fibers with low elongation as reinforcing fibers will suffer brittle fracture, and the elongation will be reduced to some extent. Even glass fibers with a large diameter will break in a state close to brittle fracture, and the extent to which the molded product absorbs impact energy is not so great, and this type of molded product is problematic when used in areas that are subject to impact. One solution to this problem is to improve the structure and shape of the molding to increase its ability to absorb impact energy, but it is always easy to match the shape of the molding to the area in which it will be used. That's not the point. Yet another method is a so-called hybrid method in which two or more types of reinforcing fibers are used in combination.
However, when using ordinary organic fibers in combination with carbon fibers or glass fibers, heating is performed to the curing temperature of the resin to be impregnated in the case of thermosetting resins, or to its melting point or softening point in the case of thermoplastic resins. Since it is necessary to impregnate the fibers with resin, the organic fibers must be sufficiently resistant to the curing heating temperature, melting point temperature, or softening point temperature. (Means for Solving the Problems) An object of the present invention is to improve the above-mentioned drawbacks and provide a fiber-reinforced resin molded product having excellent strength and rigidity as well as excellent impact resistance. That is, the present invention provides a fiber-reinforced resin molded article, in which the fibers reinforcing the outer layer of the molded article are molten liquid crystal wholly aromatic polyester fibers with a tensile modulus of 4 t/mm ² or more, and the inner layer is reinforced with fiber-reinforced resin moldings. The fibers are made of inorganic fibers with a tensile modulus of 6t/mm2 ^or more, and the total amount of these outer layer fibers and inner layer fibers accounts for 30 to 80% by volume in the molded product.
This is a fiber-reinforced resin molded product characterized by a ratio of . The molded product of the present invention may have various shapes, such as a cylindrical shape, a plate shape, an H shape, and a T shape. In these, the inner layer of the molded product, that is, the reinforcing fiber on the side that becomes the core, is a resin layer with a reinforcing material made of inorganic fiber with high rigidity (tensile modulus ≥ 6t/mm ² ), and the outer layer has a tensile modulus of 4t. By arranging each fiber so that it has a resin layer containing molten liquid crystal fully aromatic polyester fibers of molten liquid crystal or fully aromatic polyester fibers with a size of 1/mm ² or more, it is possible to absorb a large amount of energy upon impact, which was not possible with conventional hybrid molded products. I found something. The greatest finding of the present invention is that the molten liquid crystal wholly aromatic polyester fiber and inorganic fiber as described above are hybridized with the composition as described above. has no energy absorption effect. If the molded product of the present invention has excellent energy absorption, even if a local impact is applied from the outside during use, the molded product will not cause brittle fracture and will dent without making a hole. It stops changing. Furthermore, when normally used members such as automobile beams and helmets are subjected to impact, they are often subjected to impact at high speed and in a short period of time, that is, in an instant. As such, it has excellent shock absorption ability when it is hit at high speed. Although the fibers used in the present invention are basically used in the form of filament yarns, similar results can be obtained by using at least one of them in the form of a woven fabric or the like. Regarding the ratio of the inner and outer layer fibers in the molded product of the present invention, in order to cover the fragility of the inner layer fibers with the outer layer fibers, it is desirable that the outer layer fibers be used at 20% by volume or more, preferably 50% by volume or more of the inner layer fibers. In addition, the total amount of these inner layer fibers and outer layer fibers in the molded product is 30 to 80% by volume, particularly preferably 45% by volume.
The proportion is ~70% by volume. As the organic fiber having a tensile modulus of 4t/mm ² or more used in the present invention, a molten liquid crystal wholly aromatic polyester fiber is used. The molten liquid crystal wholly aromatic polyester referred to herein is an aromatic polyester that can be melt-processed by condensation of one or more aromatic hydroxy acids, optionally with aromatic diols and/or aromatic diacids, It is a wholly aromatic polyester, which is called wholly aromatic in the sense that at least one aromatic ring of each component present contributes to the polymer main chain, and is a so-called thermoplastic polyester that can form an anisotropic melt phase. Tropic liquid crystalline wholly aromatic polyester. Among these wholly aromatic polyesters, hydroxybenzoic acid, especially p-hydroxybenzoic acid and 6
-Polyesters with hydroxy-2-naphthoic acid, and these copolymerized with p,p'-bisphenol as a third component.In addition to polyesters,
Polyesters consisting of p-hydroxybenzoic acid, p,p'-biphenyl, terephthalic acid and/or isophthalic acid are useful, but are not limited thereto, and other It does not prevent the components from being incorporated into the polymer. On the other hand, in the present invention, examples of inorganic fibers having a tensile modulus of 6t/mm ² or more include glass fibers, carbon fibers,
There are metal fibers, etc. The resins used in the present invention include thermosetting resins such as epoxy resins, vinyl ester resins, unsaturated polyester resins, phenyl resins, and polyurethane resins, and thermoplastic resins such as polyarylates, polyether ether ketones, and polyphenylene resins. polyphenylene oxide, polyamide, polycarbonate, polysulfone, polyacetate, polyethylene terephthalate, polybutylene terephthalate, polyethylene, polypropylene, polyvinylidene chloride, polyvinyl chloride, thermoplastic polyurethane, polystyrene, styrene-butadiene-acrylonitrile copolymer ,
Styrene-acrylonitrile copolymer, etc.
Two or more of these can be used in combination. These resins contain commonly used plasticizers, heat stabilizers, light stabilizers, nucleating agents, fillers,
Appropriate amounts of dyes and pigments, processing aids, impact-resistant agents, fillers, etc. can also be added. The optimal combination of the molded product in the present invention is to use equal amounts of molten liquid crystal wholly aromatic polyester fiber as the outer layer and glass fiber in the form of filament yarn as the inner layer, and pultrude it into a rod shape with a thermosetting resin. It is clear from the following examples that the energy absorption effect of this molded product is remarkable. In the molded product of the present invention, the inner layer and outer layer can be formed simultaneously or separately by commonly used pultrusion or extrusion methods, and the shape can be formed in any way as required. It is possible to do so. For example, the cylindrical molded product of the present invention can be obtained as follows. Inorganic fibers are aligned and impregnated with resin, and drawn out through a nozzle having a constant diameter.Furthermore, molten liquid crystal wholly aromatic polyester fibers are aligned and impregnated with resin, and the inorganic fibers are drawn out through a nozzle having a constant diameter, which is arranged evenly around the nozzle. The resin is pulled out through a nozzle with a cylindrical shape, and then pulled into a concentric cylinder with molten liquid crystal wholly aromatic polyester fibers on the outside and inorganic fibers in the center. It is obtained by post-curing the resin in a high-temperature heating furnace and then cutting it into a certain length. Furthermore, it can also be molded by a method in which so-called prepregs impregnated with resin are stacked in a desired configuration and then heated under pressure. (Example) The present invention will be specifically explained below using examples, but the present invention is not limited by these.
In the examples, the bending strength, bending modulus, and total energy until fracture were measured based on a bending test using three-point bending as shown in FIGS. 1 and 2. Example 1 Tensile modulus so that each volume ratio is 25%
A glass roving (manufactured by Asahi Fiberglass) of 7 t/mm ² and a molten liquid crystal polyester fiber with a tensile modulus of 5 t/mm ² ; Vectran (manufactured by Kuraray) were separately drawn together so that the glass roving was surrounded by Vectran, and a hardening agent was added. After impregnating with unsaturated polyester resin (manufactured by U-Pica Japan), a resin layer with a diameter of 7 mm is formed, in which the resin accounts for 50% by volume and the center layer (inner layer) contains glass fiber, and the outer layer (outer layer)
was hardened while being pulled out through a die at a portion heated to 110° C. to obtain a fiber-reinforced resin molded product. The physical properties of the molded product (rod) obtained are shown in Table 1, and it had excellent impact resistance as shown by the total amount of energy required to break. Example 2 Glass roving (manufactured by Asahi Fiberglass) with a tensile modulus of elasticity of 7t/mm ² in terms of volume ratio: 38.5%, tensile modulus of elasticity of 7t/mm 2
A drawn rod was obtained in the same manner as in Example 1, except that the fibers were made of 5t/mm ² molten liquid crystalline polyester fiber and 11.5% Vectran (manufactured by Kuraray). The physical properties of the obtained rod are shown in Table 1, and it showed excellent shock absorption properties. Comparative Example 1 Glass rovings (manufactured by Asahi Fiberglass) with a tensile modulus of elasticity of 7 t/ ^mm2 , which is 50% by volume, were impregnated with unsaturated polyester resin (manufactured by Nippon U-Pica) containing a hardening agent, and the resin increased in volume. 50% of the ratio and the diameter is
A cylindrical molded product was obtained in the same manner as in Example 1 by passing it through a die so that the diameter was 10 mm. The physical properties of the obtained molded product are shown in Table 1, and the impact absorption energy was smaller than that of Example 1. Comparative Example 2 A rod was obtained by exchanging the inner and outer layer fibers in Example 1 and performing pultrusion molding. The physical properties of the obtained rod are shown in Table 1, and the impact absorption energy was far inferior to that of Example 1. Comparative Example 3 According to Example 1, a drawn rod was obtained by mixing resin-impregnated glass rovings and liquid crystal fibers to form a cross section of the rod. The physical properties of the obtained rod are shown in Table 1, and the impact absorption energy was inferior to that of the example. Example 3 Glass roving (manufactured by Asahi Fiber Glass) with a tensile modulus of 7t/ ^mm2 in terms of volume ratio, 44%, tensile modulus
A drawn rod was obtained in the same manner as in Example 1, except that the fibers were molten liquid crystalline polyester fibers of 5t/mm ² and 6% Vectran (manufactured by Kuraray). The physical properties of the obtained rod are shown in Table 1. Although the impact absorption energy was inferior to Examples 1 and 2, there was no problem in practical use. (Effects of the Invention) The fiber-reinforced resin molded product of the present invention has extremely superior shock absorption properties compared to conventional fiber-reinforced resin molded products.

【table】

【table】 [Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the fulcrum and the point at which a load is applied when performing a three-point bending test on a rod sample. FIG. 2 is a diagram showing the relationship between the SS curve, bending strength, bending modulus, and total energy until fracture of the molded product of the present invention. In the figure, the initial tangent line represents the elastic modulus, and the shaded area represents the total energy up to failure. 1... Molded rod of the present invention, 2... Fulcrum, 3
……load.

Claims (1)

[Claims] 1. A resin molded product reinforced with fibers, in which the fibers reinforcing the outer layer of the molded product have a tensile modulus of 4t/
Molten liquid crystal fully aromatic polyester fiber with a size of mm ² or more, fibers reinforcing the inner layer are made of inorganic fibers with a tensile modulus of 6t/mm ² or more, and the total amount of these outer layer fibers and inner layer fibers is 30 to 80% by volume in the molded product. A fiber-reinforced resin molded article characterized by a proportion of . 2. The molded article according to claim 1, wherein the inorganic fiber is at least one type of inorganic fiber selected from the group consisting of glass fiber, carbon fiber, and metal fiber. 3. The molded product according to claim 2, wherein the mineral is made of glass fiber. 4. The molded article according to claims 1 to 3, wherein the resin is a thermosetting resin.