JP7514474B2 - Pultrusion products - Google Patents

Description

The present invention relates to a pultrusion molded product made by impregnating a laminate of a textile substrate with a resin.

Molded products made of reinforcing fibers and molding resins are lightweight and have excellent mechanical properties, and are therefore widely used in sporting goods, aerospace, and general industrial applications. Molded products can be manufactured using a variety of methods, including injection molding, extrusion molding, prepreg, autoclave, and pultrusion molding.

Among them, the pultrusion method, as described in Patent Document 1, is a manufacturing method in which reinforcing fibers and molding resin are continuously passed through a mold and continuously pulled out while being impregnated, and has the advantage of being able to continuously mold fiber-reinforced composite materials.

JP 2012-240317 A JP 2008-038082 A

In the pultrusion method, reinforcing fibers that are normally aligned in one direction are pulled into a heated molding die along the pulling direction (Patent Document 2). The pultrusion molded body obtained in this way contains reinforcing fibers oriented in the pulling direction, and therefore has excellent strength in the pulling direction. However, the strength of the pultrusion molded body in directions other than the pulling direction is insufficient.

For this reason, in the pultrusion molding method, it is expected that a high-strength molded product can be efficiently manufactured by impregnating a woven fabric with a molding resin using a pultrusion molding device such as that shown in Figure 4. However, in the pultrusion molding method using a woven fabric, a woven fabric substrate having a woven structure such as that shown in Figure 5 (A) is pulled out along the inner surface of the mold, so that the hardened molding resin that is generated along the dents in the woven fabric substrate that are continuous in the molding direction may remain on the inner surface of the mold, causing dents and abrasions in the molded product during the hardened product pultrusion molding process.

The objective of the present invention is to consistently provide pultrusion molded products with good appearance and minimal dents or scratches.

In order to solve the above problems, the pultrusion molded product according to the present invention is a pultrusion molded product formed by stacking woven substrates consisting of mutually intersecting warp and weft threads, impregnating the substrate with resin, and pultrusion in the warp direction, and is characterized in that one warp thread constituting the woven substrate arranged in the outermost layer necessarily has an intersection point where it crosses one weft thread on the inside of the stacking direction alongside other adjacent warp threads. With such a pultrusion molded product according to the present invention, the weft thread that crosses two or more adjacent warp threads of the woven substrate of the outermost layer on the outside of the stacking direction and is arranged on the outermost surface side of the laminate can scrape off the resin adhering to the inner surface of the mold in the pultrusion molding process, effectively preventing the accumulation of the cured resin inside the mold.

In the above pultrusion molded product, it is preferable that the warp thread intersects with a weft thread on the inside of the lamination direction, side by side with other adjacent warp threads, at more than half of the intersections of all intersections where the warp thread intersects with the weft thread. By having a weft thread that functions as a scraper to scrape off resin adhering to the inner surface of the mold at more than half of the intersections of one warp thread, it is possible to more effectively prevent the accumulation of hardened resin inside the mold.

According to the present invention, the weft yarns arranged on the outermost surface of the woven fabric substrate laminate can prevent the resin cured material from remaining inside the mold, making it possible to provide a pultrusion molded product that is less prone to dents and abrasions and has an excellent appearance.

1A and 1B show the weave of a woven fabric substrate disposed in the outermost layer of a pultrusion molded product according to one embodiment of the present invention, in which (A) is a surface view and (B) is a schematic view. 1A to 1C are schematic diagrams showing variations of the weave of a fabric substrate arranged in the outermost layer of a pultrusion molded product according to another embodiment of the present invention. 1A to 1F are schematic diagrams showing variations in the weave of a woven fabric substrate arranged in the outermost layer of a pultrusion molded product according to yet another embodiment of the present invention. FIG. 1 is a schematic diagram showing an apparatus configuration for producing a pultrusion molded product from a woven substrate. 1A and 1B show the weave of a woven fabric substrate disposed in the outermost layer of a pultrusion molded product according to a conventional technique, in which (A) is a surface view and (B) is a schematic view.

Preferred embodiments of the present invention will now be described with reference to the drawings.
Fig. 1 shows the weave of a woven fabric substrate arranged in the outermost layer of a pultrusion molded product according to one embodiment of the present invention. In manufacturing a pultrusion molded product, a woven fabric substrate 2 is set in a pultrusion molding device 1 shown in Fig. 4, and the woven fabric substrate 2 is bundled into multiple layers using a core/shaping tool 3, and then drawn into a mold 4 equipped with a heater, where it is mixed with a molding resin 5 that has been injected separately. The molding resin 5 is impregnated into the woven fabric substrate 2 in the mold 4 and hardens, and is pulled out of the mold 4 and cut to a predetermined length by a cutter 6 to form a pultrusion molded product.

Figure 1 (A) is an external surface view of a woven fabric substrate with a satin weave, with the arrow indicating the drawing direction in the pultrusion molding process. The warp threads are arranged to coincide with the drawing direction, and more weft threads are exposed than warp threads on the front surface of the outermost layer of the laminated woven fabric substrate. For the convenience of explaining the method of expressing the woven fabric structure, the repeating units corresponding to the schematic diagram in Figure 1 (B) are enclosed in a white frame.

Figure 1 (B) shows a twill weave fabric, and is a schematic representation of the repeating unit in Figure 1 (A) surrounded by a white frame. The black squares indicate the intersections of the warp and weft threads where the warp threads are exposed on the front surface of the outermost layer and the weft threads are hidden on the back surface of the outermost layer. Conversely, the white squares indicate the intersections where the warp threads are hidden on the back surface of the outermost layer and the weft threads are exposed on the front surface of the outermost layer. The vertically long ovals drawn between adjacent white squares indicate the areas where two warp threads that cross the weft thread on the back surface of the outermost layer (inside the lamination direction) are adjacent to each other. In this area, the weft thread moves while coming into contact with the inner surface of the mold when the laminate is pulled out, so even if the hardened molding resin that occurs along the depressions between the warp threads remains on the inner surface of the mold, the hardened molding resin can be scraped off at this area.

Figures 2(A) to (C) are schematic diagrams showing variations in the weave of the woven fabric substrate arranged in the outermost layer of the pultrusion molded product according to another embodiment of the present invention. The schematic diagrams show the repeating units of the weave in the same manner as in Figure 1(B), with Figure 2(A) showing a 2/1 twill weave, Figure 2(B) showing a 2/2 twill weave, and Figure 2(C) showing the 2/2 twill weave of Figure 2(B) reversed. As with the satin weave woven fabric substrate shown in Figure 1, the weft threads in the area shown by the vertically long oval move while contacting the inner surface of the mold, so that even if the cured resin accumulates between the warp threads and adheres to the inner surface of the mold, the cured resin can be scraped off.

Figures 3(A) to (F) are schematic diagrams showing variations in the weave of the woven fabric substrate arranged in the outermost layer of a pultrusion molded product according to yet another embodiment of the present invention. The schematic diagrams show the repeating units of the weave in the same manner as in Figure 1(B), with Figure 3(A) showing a 3/1 twill weave, Figure 3(B) showing a 4-ply 3-interleaved satin weave, Figure 3(C) showing a 5-ply 2-interleaved satin weave, Figure 3(D) showing a 5-ply 3-interleaved satin weave, Figure 3(E) showing a 7-ply 2-interleaved satin weave, and Figure 3(F) showing an 8-ply 3-interleaved satin weave. In Figure 3, the areas shown by the vertically long ovals appear with a frequency of more than 50% in the warp direction of the woven fabric substrate, so that the cured resin adhering to the inner surface of the mold can be reliably scraped off.

As long as the effects of the present invention are not impaired, there is no particular limitation or restriction on the type of fiber that can be used in the woven substrate. Examples include glass fibers such as S-glass, S-1 glass, S-2 glass, S-3 glass, E-glass, and L-glass fibers, organic fibers such as carbon fibers and aramid fibers, and natural/bio fibers. In particular, when carbon fibers are used, a fiber-reinforced plastic molded product that has significantly high strength and rigidity and is also lightweight can be obtained. Examples of suitable carbon fibers are carbon fibers having a standard elastic modulus of about 200 to 250 GPa ("TORAYCA" (registered trademark) T300, T300B, T400HB, T700SC, Z600), carbon fibers having an intermediate elastic modulus of about 250 to 300 GPa ("TORAYCA" (registered trademark) T800SC, T800HB, T830HB, T1000GB, M30SC), or carbon fibers having a high elastic modulus of more than 300 GPa ("TORAYCA" (registered trademark) M35JB, M40JB, M46JB, M50JB, M55J, M55JB, M60JB), all manufactured by Toray Industries, Inc. Among these carbon fibers, it is preferable to use carbon fibers having a tensile strength of 4500 MPa or more and an elongation of 1.5% or more for the warp yarn. Since thread breakage during molding is unlikely to occur, molding is easier. These fibers may be surface-treated. Examples of surface treatments include treatment with a coupling agent, treatment with a sizing agent, treatment with a binding agent, and treatment with an additive. These fibers may be used alone or in combination of two or more types.

The number of carbon fiber filaments used in the woven substrate may be anywhere between 1,000 and 50,000. If the number of filaments exceeds 50,000, it may be difficult to impregnate the resin during molding. Filament counts of 3,000, 6,000, and 12,000 are particularly preferred in terms of cost and weaving ability.

Fiber-reinforced resins are composed of reinforcing fibers and a matrix resin, and the matrix resin can be a thermosetting resin such as epoxy resin, unsaturated polyester resin, vinyl ester resin, phenol (resol type) resin, or polyimide resin. Among these, vinyl ester resin is preferable in terms of adhesion to carbon fiber, and the mechanical properties and moldability of the molded body.

It is also preferable that the weight fiber content of the carbon fiber in the fiber-reinforced resin is in the range of 15 to 80% by weight. If the content is less than 15% by weight, the load-bearing capacity and rigidity are lost and the intended function cannot be achieved. If the weight content exceeds 80% by weight, problems such as the generation of voids in the fiber-reinforced resin are likely to occur, making molding difficult. When a high elastic modulus and high strength are required for long products, it is preferable to set the management tolerance range of the weight content to a small value, preferably a weight content of 30 to 75% by weight, and more preferably 40 to 75% by weight.

[Example 1]
Using the pultrusion molding apparatus shown in FIG. 4, a plurality of fabric base materials having the weave pattern shown in FIG. 3(B) (four-ply, three-interlace satin weave) were laminated and impregnated with resin, and the laminated fabric was molded while being pulled in the warp direction to produce a pultrusion molded product.

When the depth of the dent was measured using a depth gauge with the surface on which the dent occurred as the reference surface, there were no visible dents and the appearance was good. The depth of the dent measured by moving the depth gauge was less than 5% of the thickness of the outermost woven fabric substrate. The results are shown in Table 1.

[Comparative Example 1]
Using the pultrusion molding apparatus shown in FIG. 4, a plurality of woven fabric base materials having the woven fabric structure (plain weave) of FIG. 5(B) were laminated and impregnated with resin, and the laminated fabric base materials were molded while being pulled in the warp direction to produce a pultrusion molded product.

The depth of the dent was measured using a depth gauge with the surface on which the dent occurred as the reference surface. It was found that the dent had occurred along the warp direction on the design surface (outermost surface), and its depth was 90% or more of the substrate thickness of the outermost layer. The results are shown in Table 1.

The pultrusion products of the present invention can be widely used as various materials that require strength and light weight.

1 Pultrusion molding device 2 Woven fabric substrate 3 Core/shaping tool 4 Mold 5 Molding resin 6 Cutter

Claims (2)

A pultrusion molded product formed by layering a woven fabric substrate made of intersecting warp and weft threads, impregnating the substrate with resin, and drawing the layer in the warp direction, characterized in that one warp thread constituting the woven fabric substrate arranged in the outermost layer necessarily has an intersection point where it crosses one weft thread on the inside of the layering direction alongside the other adjacent warp threads. The pultrusion molded product according to claim 1, in which the warp threads cross one weft thread on the inside in the stacking direction alongside other adjacent warp threads at more than half of all crossing points where the warp threads cross one weft thread.

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