TW202128879A - Method for producing molded article - Google Patents

Abstract

To provide a method for producing a molded article that has excellent bending fatigue resistance and that is suited to applications where bending is applied repeatedly. A method for producing a molded article having a thickness of 0.1-2 mm in which a polyamide resin composition is injection-molded, wherein the polyamide resin composition includes polyamide-resin-bonded carbon fiber bundles obtained by bonding and integrating carbon fiber bundles using polyamide resin that has a relative viscosity of 1.4-2.9 and cutting the carbon fiber bundles to a length of 0.5-25 mm, the content ratio of carbon fibers in the polyamide resin composition is 0.5-8% by mass, and the carbon fiber length included in the molded article is 0.5-2.5 mm.

Description

Injection molded products

The present invention relates to a method for manufacturing a molded product that has good bending fatigue properties and is suitable as a bottom part of footwear such as shoes (boots).

The soles of sports shoes, such as jogging shoes, are repeatedly bent when they are manufactured and when they are actually put on and used. Therefore, the bending fatigue resistance must be good for the bending resistance strength evaluation standard.

Japanese Patent Laid-Open No. 5-168503 describes the invention of a shoe sole (especially a shoe sole for sports shoes), in which the supporting sole is composed of a body made of synthetic resin and fibers processed in the synthetic resin. And at least one fiber composite part that is mutually combined with other sole bodies by welding or chemical bonding. However, it does not specifically describe the means for improving bending fatigue.

Japanese Patent Laid-Open No. 2014-511143 describes the invention of a composite material part for footwear, which can be used for the bottom of footwear and has a fiber reinforced layer, and that the aforementioned fiber reinforced layer is adapted to the characteristics and characteristics of the wearer. The purpose of use is to provide the sole with desired flexibility (paragraph number 0008).

In addition, at the beginning of paragraph number 0040, it is stated that "other factors affecting the flexibility of the composite material part 14 are the structure and thickness of each fiber reinforced layer. In some embodiments, each fiber reinforced layer includes a resin member and A fiber-containing component.".

However, there is no specific description about the thickness of the fiber-reinforced layer, and although many resins and many fibers are exemplified, the relationship between the specific combination and the effect is not described.

The subject of the present invention is to provide a method for manufacturing a molded product that has good rigidity and bending fatigue properties and is suitable for applications such as repeated bending.

The present invention provides a method for manufacturing a molded product, which is a method for manufacturing a molded product with a thickness of 0.1-2 mm by injection molding a polyamide resin composition. The aforementioned polyamide resin composition contains a carbon fiber bundle to which a polyamide resin is attached, and the carbon fiber bundle to which a polyamide resin is attached is an object in which a polyamide resin having a relative viscosity of 1.4 to 2.9 is attached to the carbon fiber bundle and integrated Is cut into length 0.5～25mm, The content of carbon fiber in the polyamide resin composition is 0.5-8% by mass, The length of the carbon fiber contained in the aforementioned molded product is 0.5 to 2.5 mm.

The molded product obtained according to the manufacturing method of the present invention has good rigidity, and therefore has excellent load resistance and good bending fatigue resistance. Therefore, it will not be damaged even if it is repeatedly bent during manufacture and use.

[Form to implement the invention]

＜Polyamide resin composition＞ The carbon fiber bundle to which the polyamide resin is attached, contained in the polyamide resin composition, is an object in which the polyamide resin is adhered to the carbon fibers neatly bundled in the longitudinal direction and integrated and cut into a length of 0.5-25mm. Winner.

Carbon fiber is sold in the market in the form of a yarn bundle of carbon fiber bundles composed of many monofilaments. The thickness, number, and length of the carbon fiber are not particularly limited, and the diameter of the monofilament is preferably 20 μm or less, preferably 15 μm or less, and more preferably 10 μm or less. The total fineness of the carbon fiber is preferably 400 to 3000 Tex, and the number of single filaments of the carbon fiber is preferably 1000 to 100,000, preferably 3000 to 50,000.

The adhesion of the polyamide resin to the carbon fiber yarn bundle (carbon fiber bundle) can be carried out by applying the method described in the Examples of JP 2013-107979 A, etc. The adhesion can be achieved by, for example, adding additives as necessary to continuously draw the carbon fiber yarn bundle through the cross-head die, and at the same time supply the molten polyamide resin to the cross-head die from the extruder, so that the polyamide resin adheres to the aforementioned cross-head die. Carbon fiber yarn bundle to carry out.

The carbon fiber bundles to which the polyamide resin is adhered can be divided into the following three forms according to the adhesion state. (I) A fiber bundle in a state where the polyamide resin penetrates (impregnates) to the center of the carbon fiber bundle, and the polyamide resin enters between the carbon fibers constituting the center part of the carbon fiber bundle (hereinafter referred to as "polyamide resin impregnated carbon fiber bundle") . (II) A fiber bundle in a state where only the surface of the carbon fiber bundle is covered with polyamide resin (hereinafter referred to as "polyamide resin surface-coated carbon fiber bundle"). (III) Fiber bundles between these (the surface of the carbon fiber bundles are covered with polyamide resin, and the polyamide resin is impregnated to the vicinity of the surface, and the polyamide resin does not enter the central part) (hereinafter referred to as "polyamide resin" The amide resin is partially impregnated with carbon fiber bundles").

In the present invention, the polyamide resin of (I) is preferably impregnated with carbon fiber bundles. The resin-attached fiber bundles of the forms of (I) to (III) are described in the above-mentioned Japanese Patent Application Publication No. 2013-107979 (however, polyamide resin is not used in the aforementioned publication).

The relative viscosity of the polyamide resin is 1.4-2.9, preferably 1.4-2.0.

The polyamide resin is preferably an aliphatic polyamide, and polyamide 6, polyamide 66, polyamide 610, polyamide 11, polyamide 12, or a mixture of these can be used, preferably polyamide Amine 12.

As the carbon fiber bundle, the sizing agent-coated carbon fiber bundle described in Examples 1 to 4 of JP 2014-181418 A, and the fiber bundle prepreg epoxy resin described in JP 2012-56980 A can be used. The carbon fiber bundle contained in the resin composition, the product name "TORAYCA T700SC-12000 (T700SC-12K)" manufactured by Toray Co., Ltd., and the product name "TORAYCA T700GC-12000 (T700GC-12K)" manufactured by Toray Co., Ltd. Wait.

The length of the carbon fiber bundle to which the polyamide resin is adhered is 0.5 to 25 mm, preferably 3.0 to 20 mm, preferably 5.0 to 15 mm, more preferably 7.0 to 12 mm. The length of the carbon fiber bundle to which the polyamide resin is adhered is the same as the length of the carbon fiber in the fiber bundle.

As for the polyamide resin composition, in addition to articles consisting only of the above-mentioned polyamide resin-attached carbon fiber bundles, it is also possible to use polyamides that are mixed with the above-mentioned polyamide resin-attached carbon fiber bundles. An article composed of a mixture of amine resins. That is, the polyamide resin composition may contain the same polyamide resin as the polyamide resin to which the carbon fiber bundles to which the polyamide resin is attached, and/or a polyamide resin different from the aforementioned polyamide resin. When the polyamide resin composition is composed of a mixture, the polyamide resins mixed with the carbon fiber bundles to which the polyamide resin is attached may be the same or different, and the relative viscosity is preferably 1.6 or more.

The content of carbon fibers in the polyamide resin composition is 0.5 to 8% by mass, preferably 0.5 to 5% by mass, more preferably 0.5 to 3% by mass, and the remaining proportion is the content of the polyamide resin.

The polyamide resin composition may contain other well-known ingredients, such as flame retardants, flame retardant additives, heat stabilizers, slip agents, light stabilizers, antioxidants, and colorants, within the scope of solving the problems of the present invention. , Release agent, antistatic agent.

＜Method of manufacturing molded products＞ The manufacturing method of the molded article of the present invention uses the above-mentioned polyamide resin composition and can be performed by an injection molding method.

The length of the carbon fiber bundle to which the polyamide resin is attached (that is, the length of the carbon fiber) contained in the polyamide resin composition is 0.5 to 25 mm. However, the carbon fiber is melted and kneaded by an injection molding machine and injected into a metal mold. It breaks and becomes shorter during forming. That is, the length of the carbon fiber contained in the molded product may be 0.5 to 2.5 mm. The preferred length can be 0.5 to 1.5 mm.

At this time, the short carbon fiber is not easy to break, and the long carbon fiber is easy to break. In the case of ordinary single injection molding (for example, the injection molding of ISO multi-purpose test piece A-shaped product described in the examples), if the length of the carbon fiber is about 0.5mm, it will not break, and if the length of the carbon fiber is 25mm, then It will break, reaching the level below 2.5mm but not shorter than 0.5mm.

The thickness of the molded product obtained according to the manufacturing method of the present invention is 0.1 to 2 mm, preferably 0.5 to 2 mm. If the thickness of the molded product is 0.1 to 2 mm, the rigidity and fatigue bendability can be improved.

The bending elastic modulus (ISO178) of the molded article obtained by the manufacturing method of the present invention is preferably 1600 MPa or more, preferably 1600 to 3000 MPa, and more preferably 1650 to 3000 MPa. The aforementioned flexural modulus is a value of a molded product obtained only from a composition composed of polyamide resin and carbon fiber.

Hereinafter, various embodiments of the present invention will be exemplarily disclosed.

＜1＞ A method of manufacturing a molded product, which is a method of manufacturing a molded product with a thickness of 0.1-2mm by injection molding a polyamide resin composition, and The aforementioned polyamide resin composition contains carbon fiber bundles to which polyamide resin is adhered, The carbon fiber bundle to which the polyamide resin is adhered is a polyamide resin with a relative viscosity of 1.4 to 2.9. The object formed by attaching the polyamide resin to the carbon fiber bundle and integrating it is cut into a length of 0.5-25 mm. The content of carbon fiber in the polyamide resin composition is 0.5-8% by mass, The length of the carbon fiber contained in the aforementioned molded product is 0.5 to 2.5 mm.

＜2＞ The method for manufacturing a molded article as described in <1>, wherein the polyamide resin composition contains: a carbon fiber bundle to which a polyamide resin is adhered; and a polyamide resin that is the same as the polyamide resin and/or The aforementioned polyamide resins with different polyamide resins, the carbon fiber bundles with the polyamide resin attached have a relative viscosity of 1.4-2.9, preferably a polyamide resin with a relative viscosity of 1.4-2.0 attached to the carbon fiber bundles and integrated. The object is cut into a length of 0.5-25mm, preferably 3.0-20mm, preferably 5.0-15mm, more preferably 7.0-12mm.

＜3＞ The method for producing a molded article as described in <1> or <2>, wherein the content of carbon fibers in the polyamide resin composition is 0.5 to 5% by mass, preferably 0.5 to 3% by mass.

＜4＞ The method for producing a molded article as described in any one of <1> to <3>, wherein the polyamide resin contains an aliphatic polyamide, and preferably contains polyamide 6, polyamide 66, polyamide 610, Polyamide 11, polyamide 12, or a mixture of these, preferably contains polyamide 12.

＜5＞ The method for producing a molded product according to any one of <1> to <4>, wherein the thickness of the molded product is 0.5 to 2 mm, and the length of the carbon fiber contained in the molded product is 0.5 to 1.5 mm.

＜6＞ Such as the method of manufacturing a molded product in any one of <1> to <5>, wherein the molded product is the bottom part of various shoes, especially selected from sports shoes, sandals, slippers, sandals, etc., such as jogging shoes and casual shoes. Footwear.

＜7＞ A method of manufacturing a molded product, which includes: Cut the integrated carbon fiber bundle with polyamide resin with relative viscosity of 1.4～2.9 to a length of 0.5～25mm, preferably 3.0～20mm, preferably 5.0～15mm, more preferably 7.0～12mm, to make the adhesion Carbon fiber bundle with polyamide resin; The polyamide resin composition containing the aforementioned carbon fiber bundles with polyamide resin attached is produced, and the content of the carbon fibers is 0.5-8% by mass, preferably 0.5-5% by mass, preferably 0.5-3% by mass; The aforementioned polyamide resin composition is injection molded.

＜8＞ The method for manufacturing a molded article as described in <7>, wherein the molded article contains carbon fibers having a length of 0.5 to 2.5 mm, preferably 0.5 to 1.5 mm.

＜9＞ The method of manufacturing a molded product as described in <7> or <8>, wherein the thickness of the molded product is 0.1 to 2 mm, preferably 0.5 to 2 mm.

＜10＞ Such as the method of manufacturing a molded article in any one of <7> to <9>, wherein the polyamide resin composition is melted and kneaded in an injection molding machine and/or injection molded into a metal mold, and the carbon fibers of the carbon fiber bundle are broken. Make it shorter and include it in the molded product with a length of 0.5-2.5mm, preferably 0.5-1.5mm.

＜11＞ Such as the method of manufacturing a molded product in any one of <7> to <10>, wherein the molded product is the bottom part of various shoes, especially selected from sports shoes, sandals, slippers, sandals, etc., such as jogging shoes and casual shoes. Footwear. [Example]

The components used in Examples and Comparative Examples are as follows. (Polyamide (PA) resin) ‧PA-1: Polyamide 12, relative viscosity 1.6, trade name L1600 (manufactured by DAICEL EVONIK Co., Ltd.) ‧PA-2: Polyamide 12, relative viscosity 1.9, trade name L1940 (manufactured by DAICEL EVONIK Co., Ltd.)

(carbon fiber) ‧CF-1: Product name "TORAYCA T700SC-12000" (general CF), manufactured by Toray Co., Ltd., carbon fiber yarn bundle coated with epoxy compound (binding agent) ‧CF-2: Product name "TORAYCA T700GC-12000" (high-strength CF), manufactured by Toray Co., Ltd., carbon fiber yarn bundle coated with epoxy compound (bundling agent) ‧CF-3: CF cut strands, staple fiber 6mm, HTC413, manufactured by Toho Tenax Co., Ltd.

＜Relative viscosity＞ PA12 was dissolved in 96% by mass sulfuric acid at a temperature of 25° C. at a concentration of 1 g/100 ml, and then the measurement was performed.

＜Method of making test piece＞ The ISO multi-purpose test piece A-shaped product (thickness 2 mm) was produced under the following conditions. Device: J-150EII, manufactured by Japan Steel Works Co., Ltd. Material pipe temperature 280℃ Metal mold temperature: 100℃ Screw: special screw for long fiber Screw diameter: 51mm Gate shape: side gate with a width of 20mm Injection pressure: 55～80% Injection time: 1.0～1.5sec Maintain pressure: 40% Holding time: 10sec Back pressure: 10%

＜Fiber length (weight average fiber length)＞ A sample of about 3 g was cut out from the test piece, the resin was dissolved with sulfuric acid, and the carbon fiber was taken out. The weight average fiber length was obtained from a part of the fibers (500 fibers) taken out. The calculation formula is the formula described in paragraphs 0044 and 0045 of Japanese Patent Application Laid-Open No. 2006-274061.

＜Tensile strength (MPa)＞ Measured in accordance with ISO527. ＜Bending strength (MPa)＞ Measured according to ISO178. ＜Bending elastic modulus (MPa)＞ Measured according to ISO178.

＜Bending fatigue resistance＞ After the ISO dumbbell-shaped test piece is injection molded, both ends are cut, the straight part (width 10mm, thickness 2mm) is made into a test piece, and it is mounted on a testing machine (ROSS FLEXING TESTER: Yasuda Seiki Seisakusho Co., Ltd.). Then, the test was performed under the following conditions, and the case where the aforementioned test piece (10×2 mm) was not damaged was rated as ○, and the case where the test piece was damaged was rated as ×.

Angle: 90° Temperature of test tank: -3°C Test speed: 103 times/minute Number of repetitions: 50,000 times

Manufacturing example 1 (manufacturing of carbon fiber bundles impregnated with polyamide resin) The polyamide resin-impregnated carbon fiber bundles 1 and 2 used in Examples 1 to 3 and Comparative Examples 2 and 3 were manufactured according to the following method.

The carbon fiber bundles shown in Table 1 were passed through a crosshead die. At this time, PA12 in the molten state shown in Table 1 was supplied to the crosshead die in the amount shown in Table 1 from a biaxial extruder (barrel temperature 280°C), and the molten material was impregnated into the carbon fiber yarn bundle (CF- 1 or CF-2).

Then, the outlet of the cross-head die was shaped with a shaping nozzle, and the shape was adjusted with a shaping roller, and then cut into a length of 9 mm by a pelletizer, to obtain a cylindrical polyamide 12-impregnated carbon fiber bundle. The columnar carbon fiber bundle impregnated with polyamide 12 was cut from the longitudinal direction. As a result of observation, the carbon fibers were substantially parallel in the longitudinal direction.

Production Example 2 (Comparative resin particles containing CF-3) After mixing 80% by mass of PA-1 and 20% by mass of CF-3 with a drum mixer, they were melt-kneaded with an extruder (250° C.) to obtain CF-3-containing resin pellets.

[Table 1] Fiber bundle impregnated with resin 1 Fiber bundle impregnated with resin 2 PA-1 quality% 79.8 79.8 CF-1 quality% 20 CF-2 quality% 20 Stabilizer quality% 0.2 0.2 total quality% 100 100 CF content ratio quality% 20 20 Fiber bundle length impregnated with resin mm 9 9 Bending elasticity MPa 12309 13757 Tensile Strength MPa 215 241 Bending strength MPa 275 292 Charpy shock intensity kJ/m ² 14.2 15.3 proportion 1.10 1.10

Examples 1 to 3, Comparative Examples 1 to 4 The components shown in Table 2 were mixed to obtain a polyamide resin composition. Each of the above-mentioned measurements was carried out using each of the obtained compositions. The results are shown in Table 2.

[Table 2] Example Comparative example 1 2 3 1 2 3 4 Composition Fiber bundle impregnated with resin 1 (mass%) 5 10 60 Fiber bundle impregnated with resin 2 (mass%) 10 100 Resin particles containing CF-3 10 PA-1 (mass%) 95 PA-2 (mass%) 90 90 100 40 90 CF content ratio (mass%) 1.0 2.0 2.0 - 12 20 2.0 Molded product Fiber length (mm) 1.50 1.2 1.2 - 1.1 1.00 0.30 Tensile strength (MPa) 45 55 59 39 127 241 48 Flexural strength (MPa) 63 78 81 55 165 292 68 Flexural elasticity (MPa) 1700 2250 2300 1300 7258 13757 1580 proportion 1.00 1.01 1.01 1.00 1.06 1.10 1.01 Bending fatigue ○ ○ ○ ○ X X ○

Examples 1 to 3 are excellent in rigidity (tensile strength, bending strength, bending elastic modulus), light in weight, and excellent in bending fatigue resistance. Therefore, it is suitable as a sole part, especially as the sole of a sports shoe that generates a high load in an instant.

Comparative Example 1 does not contain carbon fiber, and therefore has poor rigidity. Comparative Examples 2 and 3 have a high content of carbon fibers, and therefore have high rigidity, but have poor bending fatigue properties. The length of the carbon fiber contained in the molded article of Comparative Example 4 was too short, and therefore the bending elastic modulus was low. [Possibility of Industrial Use]

By the manufacturing method of the present invention, the resulting molded article is suitable for applications that bend during manufacture and use, and is suitable for use as bottom parts of various shoes, especially sports shoes such as jogging shoes and casual shoes, as well as sandals, Shoes such as slippers and straw sandals.

Particularly, the molded product obtained by the manufacturing method of the present invention is suitable for use as a midsole equivalent to a leather shoe midsole, a wedge sole constituting a heel, and covering the entire bottom surface of the shoe to improve grounding performance among sports shoes. , All or part of the outsole to prevent abrasion.

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Claims (9)

An injection molded product composed of a polyamide resin composition with a thickness of 0.1 to 2 mm. The polyamide resin composition contains carbon fiber bundles to which a polyamide resin is attached, and the polyamide resin is attached. The carbon fiber bundle of the resin is formed by attaching a polyamide resin with a relative viscosity of 1.4 to 2.9 to the carbon fiber bundle and cutting it into a length of 0.5-25 mm. The carbon fiber in the polyamide resin composition contains The ratio is 0.5-8% by mass, the length of the carbon fiber contained in the aforementioned molded product is 0.5-2.5mm, and the test piece evaluated by the following method is not damaged. <Bending fatigue test> After injection molding the ISO multipurpose test piece A-shaped product (thickness 2mm) composed of the aforementioned polyamide resin composition, the two ends are cut off, and the straight part (width 10mm, thickness 2mm) is made into a test piece, which is mounted on Test machine (ROSS FLEXING TESTER), test according to the following conditions, angle: 90°, temperature of test tank: -3°C, test speed: 103 times/min, number of repetitions: 50,000 times. The injection molded article of claim 1, wherein the polyamide resin composition contains: a carbon fiber bundle to which a polyamide resin is attached; and a polyamide resin that is the same as the polyamide resin and/or the same as the polyamide resin Polyamide resins with different resins, the carbon fiber bundles with polyamide resin attached are polyamide resins with a relative viscosity of 1.4 to 2.9 attached to the carbon fiber bundles, and the integrated object is cut into lengths of 0.5-25mm. . The injection molded article of claim 2, wherein the content of carbon fibers in the polyamide resin composition is 0.5 to 5 mass%. The injection molded article of claim 1, wherein the content of carbon fibers in the polyamide resin composition is 0.5 to 5 mass%. The injection molded product according to any one of claims 1 to 4, wherein the polyamide resin contains polyamide 12. Such as the injection molded product of claim 5, wherein the aforementioned molded product is the bottom part of footwear. Such as the injection molded product of claim 6, wherein the aforementioned footwear includes sports shoes. The injection molded product according to any one of claims 1 to 4, wherein the aforementioned molded product is a bottom part of footwear. Such as the injection molded product of claim 8, wherein the aforementioned footwear includes sports shoes.