JP2010022582A - Shoe sole and manufacturing method of shoe sole - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of shoe soles and the shoe soles having stable quality and improved appearance, functionality and adhesiveness between a rubber part and a thermoplastic resin and to achieve a cost reduction. <P>SOLUTION: In the manufacturing method of the shoe soles, the rubber part is molded beforehand by at least partially cross-linking. The thermoplastic resin is over-molded for performing cross-linking adhesion of the rubber part and the thermoplastic resin so as to obtain the shoe sole. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a shoe sole manufacturing method and a shoe sole obtained by the manufacturing method.

  Various materials for molding a shoe sole are known. For example, Patent Document 1 discloses a sole for an athletic shoe in which a rubber surface is halogenated and then a thermoplastic plastic such as polyurethane elastomer or polyamide elastomer is molded in multiple colors on the surface of the halogenated rubber by compression molding or injection molding. A manufacturing method is disclosed.

  However, the method disclosed in Patent Document 1 requires a secondary surface activation treatment such as a primer or a pretreatment such as halogenation on the surface of the vulcanized rubber, so that the number of steps is complicated and productivity is increased. It was not good.

  Patent Document 2 discloses a composite product in which a thermoplastic material is bonded to a thermoplastic elastomer (TPV) obtained by dynamic vulcanization of rubber dispersed in a fine particle state in a thermoplastic matrix, that is, a thermoplastic plastic. An invention relating to an article comprising TPV and TPV is disclosed. Furthermore, as a shoe by insert molding or two-color injection molding, a TPV alloy (thermoplastic plastic) is placed on a sole (sole) made of polyetheresteramide that has high fatigue resistance, low deformation hysteresis, and excellent low-temperature characteristics. The formation of shoe soles by insert molding injecting / alloy) is disclosed.

  Patent Document 3 includes a lightweight thermoplastic elastomer bonded onto a dense material consisting of a non-lightweight thermoplastic selected from the group consisting of polyetheramides, polyetheresters, polyurethanes. A shoe sole comprising a two-layer article of composition is disclosed.

  However, as disclosed in Patent Document 3, the weight reduction is adhered to a dense material made of non-lightweight thermoplastic selected from the group consisting of polyetheramide, polyetherester, polyurethane. In a shoe sole composed of a two-layer article of a composition containing a thermoplastic elastomer thus formed, the durability of the shoe sole itself of the product may be lowered because the durability of the lightweight thermoplastic elastomer itself is low.

  In Patent Document 4, a composite structure obtained by combining a vulcanized elastomer containing a carboxylic acid group with a thermoplastic polymer containing a block, and a method for producing a shoe sole for an athletic shoe, wherein the elastomer is vulcanized on the thermoplastic polymer Is disclosed.

  However, Patent Document 4 discloses a composite structure obtained by combining a vulcanized elastomer containing a carboxylic acid group and a thermoplastic polymer containing a block. Although a method for producing a shoe sole for an athletic shoe in which an elastomer is vulcanized on a thermoplastic polymer is disclosed, a method for producing a shoe sole is not specifically described. However, for example, when press molding is employed, there is a problem that a rubber burr (coating) is formed on the thermoplastic polymer and the product cannot be commercialized from the appearance.

  Further, in these shoe sole manufacturing methods described above, the thermoplastic elastomer sheet is subjected to a molding temperature higher than the thermal deformation temperature, and therefore, thermal deformation and deformation during cooling remain after demolding. In order to prevent these, a cooling device is required for the bottom-end injection mold, so it is necessary to install very expensive and complicated equipment, and there is a problem that it is expensive in terms of manufacturing cost. It was. Therefore, there is a need for a shoe sole or shoe sole manufacturing method that has good durability, has an appropriate hardness and flexibility as a shoe sole material, cushioning properties and traction properties, and has good productivity and low manufacturing costs. It was rare.

  Further, in Patent Document 5, after a rubber formed of a thermosetting elastic body and an adhesive layer formed of a thermoplastic elastomer are simultaneously integrally formed, a base portion that is a shoe sole body formed of a thermoplastic elastomer is formed. A three-layered shoe sole that is integrally molded with an adhesive layer by injection molding and a method for manufacturing the three-layered shoe sole are disclosed.

However, since the three-layered shoe sole disclosed in Patent Document 5 has an adhesive layer interposed between the rubber and the base portion, the adhesion between the rubber and the base portion is sufficiently improved, and the variation in the adhesive force is also large. However, since a mold cooling process is necessary, the process is complicated and the manufacturing cost is increased.
JP-A-8-294933 JP-A-7-195622 Japanese National Patent Publication No. 8-505333 JP-T 8-5111741 JP 2000-41702 A

  The present invention overcomes the above-mentioned problems of the prior art, further improves the appearance, further reduces the cost, improves the adhesion between the rubber parts and the thermoplastic resin, stabilizes the quality, and improves the functionality. It is an object of the present invention to provide a shoe sole manufacturing method and a shoe sole that are further improved.

  In order to achieve the above object, the present invention has found a shoe sole manufacturing method having the following constitution and a shoe sole manufactured using the method.

  The present invention relates to a method for producing a shoe sole, wherein the rubber part and the thermoplastic resin are cross-linked and bonded by overmolding a thermoplastic resin onto a rubber part that is at least partially cross-linked in advance. .

The overmolding is preferably performed by injection molding.
The rubber part is preferably peroxide-crosslinked.

The rubber part preferably contains a resin highly compatible with the thermoplastic resin.
It is preferable that the thermoplastic resin and the resin highly compatible with the thermoplastic resin include one or more compounds selected from the group consisting of polyamide resins, polyamide elastomers, polyurethane resins, and polyurethane elastomers.

  The rubber component of the rubber part preferably contains 40% by mass or more of carboxylated acrylonitrile-butadiene rubber.

  The present invention further relates to a shoe sole manufactured using the method for manufacturing a shoe sole.

  According to the present invention, the rubber part and the thermoplastic resin are cross-linked and bonded by inserting the rubber part that is at least partially crosslinked in advance into the mold and overmolding the thermoplastic resin. This eliminates the need for heating and cooling the mold, so that the work process can be greatly simplified in the shoe sole manufacturing process, and cost reduction can be achieved.

  According to the present invention, since the rubber parts are at least partially cross-linked in advance and then overmolded with the thermoplastic resin, burrs do not occur when combined with the thermoplastic resin, and the appearance is improved. Therefore, the added value of the product is greatly improved.

  In addition, since the conventional rubber parts are bonded to the surface of the thermoplastic resin, complicated operations such as buffing of rubber parts, primer treatment, adhesive application, and crimping process are not required. In the shoe sole manufacturing process, the work process is greatly simplified, and it is possible to achieve cost reduction.

  According to the present invention, it is possible to further strengthen the adhesion between the rubber part and the thermoplastic resin by improving the compatibility. Since the adhesion between the rubber part and the thermoplastic resin can be strengthened, the safety factor against the adhesion variation is also increased.

  Furthermore, in the conventional laminating process, when a complicated three-dimensional solid curved surface is provided on the rubber, there is a gap or a variation in adhesive force during bonding, but according to the present invention, a uniform and high-strength bonding is achieved. It becomes possible.

Embodiments of the present invention will be described in detail below.
<Sole>
FIG. 1 is a plan view, a side view, and a cross-sectional view of a shoe sole according to the present invention. A shoe sole 1 according to the present invention includes a rubber part 2 that is at least partially crosslinked in advance, and a base 3 that is formed of a thermoplastic resin that is crosslinked and bonded to the rubber part 2 by overmolding a thermoplastic resin. It consists of

<Rubber parts>
Examples of the rubber component of the rubber part 2 in the present invention include NBR (acrylonitrile-butadiene rubber), X-NBR (carboxylated acrylonitrile-butadiene rubber), X-SBR (carboxylated styrene-butadiene rubber), BR (butadiene). ), CR (chloroprene rubber), EPM (ethylene-propylene rubber), EPDM (ethylene-propylene-diene), SBR (styrene-butadiene rubber), NR (natural rubber), and the like.

  When a rubber component having a high polarity is used, X-NBR is preferably used from the viewpoint of obtaining a stronger adhesion. X-NBR is more preferably contained in an amount of 40% by mass or more in the rubber component of rubber parts.

  The rubber part 2 is at least partially cross-linked in advance, and is preferably peroxide cross-linked from the viewpoint of cross-linking adhesion with the base 3 made of a thermoplastic resin.

  The rubber part 2 of the present invention preferably contains a resin (hereinafter also referred to as “mixed resin”) that is highly compatible with the thermoplastic resin of the base 3 from the viewpoint of improving the adhesive strength by fusion bonding.

  The rubber part 2 of the present invention can be composed of two layers of an outer layer on the grounding surface side and an inner layer adjacent to the base portion 3 made of a thermoplastic resin. In this case, the inner layer preferably contains a mixed resin.

  In addition, the outer layer of the rubber part is preferably a rubber excellent in properties required for the ground contact surface of the shoe sole, such as wear resistance, grip properties, and oil resistance.

  The rubber part 2 preferably has a thickness of 1.0 to 20.0 mm. Moreover, when the rubber part 2 consists of two layers of an outer layer and an inner layer, it is preferable that the thickness of an outer layer is 0.5-19.5 mm, and the thickness of an inner layer is 0.5-5.0 mm.

<Thermoplastic resin>
As the thermoplastic resin of the base 3 in the present invention, polyamide resin, polyurethane resin, polyolefin resin, polystyrene resin, polyvinyl chloride resin, polyester resin, chlorinated polyethylene resin and the like can be used, and foaming of these resins is possible. It is also possible to use the body. Foaming of these resins is performed by a method using a foaming agent such as a volatile foaming agent or a decomposable foaming agent, or a method using a microballoon. Polyamide elastomer, polyurethane elastomer, polyolefin elastomer (EVA elastomer, polyethylene elastomer, polypropylene elastomer, etc.), polystyrene elastomer, polyvinyl chloride elastomer, polyester elastomer, 1,2-polybutadiene elastomer, etc. can be used. It is.

  It is preferable to use a polyamide resin, a polyamide elastomer, a polyurethane resin, or a polyurethane elastomer from the viewpoint of obtaining a stronger adhesion with the rubber part.

<Mixed resin>
The rubber part 2 of the present invention preferably contains a resin (mixed resin) that is highly compatible with the thermoplastic resin used for the base portion 3, and the mixed resin includes a polyamide resin, a polyurethane resin, a polyolefin resin, and a polystyrene resin. , Polyvinyl chloride resin, polyester resin, chlorinated polyethylene resin, polyamide elastomer, polyurethane elastomer, polyolefin elastomer (EVA elastomer, polyethylene elastomer, polypropylene elastomer, etc.), polystyrene elastomer, polyvinyl chloride elastomer, polyester elastomer, 1, It is possible to use 2-polybutadiene elastomer.

  The mixed resin is highly compatible with the thermoplastic resin used for the base 3. In the present invention, the “resin highly compatible with the thermoplastic resin” refers to a resin that has good compatibility with the thermoplastic resin and softens due to the heat when the thermoplastic resin is overmolded. Specific examples include (1) resins and elastomers similar to the thermoplastic resin, and (2) elastomers whose soft segment or hard segment is similar to the thermoplastic resin. As an example of the above (1), when the overmolded resin is a polyamide elastomer, the mixed resin is a polyamide elastomer, the overmolded resin is a polyurethane elastomer, and the mixed resin is a polyurethane elastomer, (2 As an example, when the resin to be overmolded is a polyether block polyamide elastomer, the mixed resin is a polyether block polyurethane elastomer.

  From the viewpoint of improving adhesiveness by fusion, it is preferable to use a resin having a lower melting point and softening point than the thermoplastic resin of the base 3 as the mixed resin.

  The mixed resin is preferably in the form of pellets or powder. In the case of pellets, the resin is melted and kneaded into the rubber compound. In the case of pellets, the average particle diameter is preferably 1 mm to 7 mm, and in the case of powder, the average particle diameter is preferably 10 μm to 1 mm. In the case of powder, if the average particle size is less than 10 μm, the effect of enhancing the adhesion between the rubber part and the thermoplastic resin is not exhibited. Moreover, when an average particle diameter exceeds 1 mm, the physical property of rubber parts will fall. The average particle size of the powdered mixed resin is more preferably 50 to 200 μm.

  The mixed resin preferably contains 1 to 60 parts by mass with respect to 100 parts by mass of the rubber component of the rubber part. When the content of the mixed resin is less than 1 part by mass, the effect of improving the adhesion between the rubber part and the thermoplastic resin is not exhibited. Moreover, when the content exceeds 60 parts by mass, it is not preferable because it is difficult to remove the rubber parts from the mold and a cooling process is required. The content is preferably 5 to 40 parts by mass.

  The mixed resin is preferably uniformly dispersed in the rubber part from the viewpoints of further strengthening the adhesiveness between the rubber part and the thermoplastic resin and improving the rubber physical strength.

<Crosslinking agent>
As the crosslinking agent for the rubber part 2 of the present invention, an organic peroxide that promotes peroxide crosslinking is preferably used. Examples of organic peroxides include alkyl peroxides and acyl peroxides. Among them, DCP (dicumyl peroxide) and di-t-butylperoxy-3.3.5-trimethylcyclohexane may be used. preferable.

<Other ingredients>
The rubber part 2 of the present invention can contain a softener, carbon black, a white filler, a surfactant and the like.

  The softener is used in combination to further improve the kneadability if desired. For example, petroleum softeners such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, and petroleum jelly; castor oil and linseed oil Fat oil-based softening agents such as rapeseed oil and coconut oil; tall oil; sub; waxes such as beeswax, carnauba wax and lanolin; linoleic acid, palmitic acid, stearic acid, lauric acid and the like can be used.

  As the white filler, for example, silica, clay, alumina, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, magnesium hydroxide, magnesium oxide, titanium oxide and the like can be used, and these can be used alone or in combination of two or more. It can be used by mixing. Particularly preferred white fillers are silica, clay, aluminum hydroxide, and alumina.

  As the surfactant, for example, polyethylene glycol, diethylene glycol and the like can be used, and a particularly preferable surfactant is polyethylene glycol.

<Shoe sole manufacturing method>
The manufacturing method of the shoe sole 1 which concerns on this invention is demonstrated using FIGS.

[Embodiment 1]
Embodiment 1 of the present invention will be described with reference to FIG.

(Production of rubber parts)
First, the rubber part material 4a obtained by die-cutting the kneaded and dispensed sheet of uncrosslinked rubber and mixed resin is placed in the recess 6 of the rubber part molding die 5 and subjected to pressure heating (150 to 160 ° C.) (FIG. 2 (a), (b)). Next, the mold is opened when the rubber part material 4a is at least partially crosslinked. That is, mold opening is performed at a location corresponding to the time region A of the rheometer cross-linking curing curve in FIG. 4. The time region A varies depending on the rubber composition and is adjusted by the thickness and shape of the molded product. Although it is necessary, in the case of a general shoe sole, it is desirable to be within 3 to 8 minutes after the start of pressure heating. By leaving the undecomposed crosslinking agent in the rubber part 2 in this way, it is possible to cross-link the rubber part 2 and the thermoplastic resin in the subsequent step of overmolding the thermoplastic resin that will be the base 3. Thus, stronger adhesion can be obtained.

  Next, the rubber part 2 is removed from the mold, and burrs are cut as necessary (FIGS. 2C and 2D).

(Thermoplastic resin overmold)
Next, the rubber part 2 produced in the above process is placed so as to match the rubber part recess 8 of the shoe mold 7 for mold injection for shoe sole, and the mold is clamped (FIG. 2 (e)). Next, the thermoplastic resin is overmolded (FIG. 2 (f)).

  In the injection molding, the rubber part 2 and the thermoplastic resin 9 are cross-linked and bonded. The conditions at this time depend on the respective materials. For example, in the case of polyamide elastomer, the rubber cross-linking temperature and Although it is necessary to adjust from the melting temperature of the mixed resin and the thermoplastic resin depending on the thickness and shape of the molded product, in the case of a general shoe sole, an injection time of 5 to 20 seconds is preferable at a temperature range of 180 to 290 ° C. . As a result, the uncrosslinked portion of the rubber part 2 and the thermoplastic resin are cross-linked and bonded, and strong adhesion can be obtained.

[Embodiment 2]
According to the present invention, the rubber part can be composed of two layers of an outer layer on the grounding surface and an inner layer adjacent to the thermoplastic resin, depending on the required characteristics of the shoe sole. In this case, a rubber that can be cross-linked and bonded to the thermoplastic resin layer is used for the inner layer, and a rubber that is excellent in wear resistance and grip properties and can be cross-linked and bonded to the inner layer is used for the outer layer. A method for manufacturing a shoe sole in the case of two rubber parts will be described with reference to FIG.

(Production of rubber parts)
First, the rubber part material obtained by die-cutting the uncrosslinked rubber kneading and dispensing sheet used for the outer layer is placed in the concave part of the rubber part molding die (FIGS. 3A and 3B). Next, an uncrosslinked rubber kneading and dispensing sheet used for the inner layer is placed on the outer layer and heated under pressure (150 to 160 ° C.), and the rubber part materials 4b and 4c are at least partially crosslinked. Open the mold. That is, mold opening is performed at a location corresponding to the time region A of the rheometer cross-linking curing curve in FIG. 4. The time region A varies depending on the rubber composition and is adjusted by the thickness and shape of the molded product. Although it is necessary, in the case of a general shoe sole, it is desirable to be within 3 to 8 minutes after the start of pressure heating. By leaving the undecomposed crosslinking agent in the rubber part 2 in this way, it is possible to cross-link the rubber part 2 and the thermoplastic resin in the subsequent step of overmolding the thermoplastic resin that will be the base 3. Thus, stronger adhesion can be obtained.

(Thermoplastic resin overmold)
Next, the rubber part 2 produced in the above process is disposed so as to match the rubber part concave portion 8 of the shoe mold 7 for mold injection for shoe sole (FIG. 3 (e)). Next, the thermoplastic resin is overmolded (FIG. 3F).

  In the injection molding, the rubber part 2 and the thermoplastic resin 9 are cross-linked and bonded. The conditions at this time depend on the respective materials. For example, in the case of polyamide elastomer, the rubber cross-linking temperature and Although it is necessary to adjust from the melting temperature of the mixed resin and the thermoplastic resin depending on the thickness and shape of the molded product, in the case of a general shoe sole, an injection time of 5 to 20 seconds is preferable at a temperature range of 180 to 290 ° C. . As a result, the uncrosslinked portion of the rubber part 2 and the thermoplastic resin are cross-linked and bonded, and strong adhesion can be obtained.

<Examples 1-4, Comparative Examples 1-5>
(Production of rubber parts sheet)
As a rubber part sheet, a rubber compounding agent containing various compounding agents as shown in Table 2 is kneaded to prepare a dispensing sheet having a thickness of 2 mm. The dispensing sheet is placed in the recess of the rubber part molding die and heated under pressure at 160 ° C. for the crosslinking time shown in Table 2. Next, the mold is opened when the dispensing sheet is at least partially cross-linked, and the rubber part sheet is removed.

(Thermoplastic resin overmold)
Next, the rubber part sheet produced in the above process is placed so as to match the recess (depth 3.5 mm) of the mold for the thermoplastic resin test sheet, and the mold is clamped. Thereafter, a polyamide elastomer (PEBAX 6333, manufactured by Arkema Co., Ltd.) is injection-molded as a thermoplastic resin at a molding temperature of 260 ° C. and an injection time of 10 seconds (thickness: 1.5 mm). After holding for 25 seconds after injection, the mold is removed.

  The rubber / thermoplastic resin composite test sheet thus obtained (size 200 mm × 50 mm × 3.5 mm) is measured for peel strength and material fracture rate test.

(Measuring method)
The peel strength is measured at a peel rate of 50 mm / min by a test method in accordance with “JIS K 6256-1993 Adhesion Test Method for Vulcanized Rubber” and is determined based on the criteria in Table 1. In addition, adhesive strength is excellent and durability improves, so that a measured value is large.

  The material fracture rate is obtained by observing the peeled surface after measuring the peel strength and visually calculating the ratio (%) of the rubber layer to the peeled total area.

  The measurement results for each formulation are shown in Table 2.

X-NBR (carboxylated acrylonitrile-butadiene rubber): manufactured by Nippon Zeon Co., Ltd., NX775
NBR: JSR, NBR230SL
NR: Made in Vietnam, SVR-3L
SBR: JSR, SBR1502
Mixed resin: Arkema, PEBAX MX1205 (average particle size 100 μm, powder)
Stearic acid: manufactured by Nippon Oil & Fats, bead stearic acid silica: manufactured by Evonik Degussa, Ultrasil Vn3
Surfactant: PEG4000 manufactured by Zenyaku Kogyo
Anti-aging agent: Nouchi SP, manufactured by Ouchi Shinsei Chemical
Crosslinking agent: manufactured by NOF Corporation, Park Mill D-40
Sulfur: Made by Hosoi Chemical, fine powder sulfur (200 mesh)
Vulcanization accelerator DM: Nouchi DM, manufactured by Ouchi Shinsei Chemical
Vulcanization accelerator M: Nouchi M, manufactured by Ouchi Shinsei Chemical
Vulcanization accelerator TS: Nouchi TS, manufactured by Ouchi Shinsei Chemical
(Evaluation results)
In Example 1, the rubber component of the rubber part is X-NBR 50% by mass, the crosslinking time is 5 minutes, and it has a sufficient peel strength and material destruction rate. Example 2 is obtained by adding a mixed resin to the formulation of Example 1, but has a peel strength and a material breakage rate that are further superior to Example 1. In Example 3, the rubber component of the rubber part contains 40% by mass of X-NBR, and has sufficient peel strength and material failure rate. In Example 4, the rubber component of the rubber part contains 80% by mass of X-NBR, and has excellent peel strength and material destruction rate.

  On the other hand, the rubber parts of Comparative Examples 1 and 2 have the same composition as in Examples 1 and 2, respectively, but the crosslinking time is 10 minutes and do not exhibit sufficient peel strength. Comparative Example 3 contains sulfur and a vulcanization accelerator instead of the peroxide (DCP-40) used in the examples as a crosslinking agent, but does not exhibit sufficient peel strength. In Comparative Example 4, the rubber component of the rubber part contains 30% by mass of X-NBR, but does not show sufficient peel strength. Comparative Example 5 contains 100% by mass of NR as a rubber component of rubber parts, but does not show sufficient peel strength.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is the top view, side view, and sectional view showing the sole according to the present invention. It is sectional drawing which shows a process for one Embodiment of the manufacturing method of the shoe sole which concerns on this invention. It is sectional drawing which shows one Embodiment of the manufacturing method of the shoe sole which concerns on this invention. It is explanatory drawing which shows the rheometer bridge | crosslinking hardening curve of the rubber part material used for the shoe sole which concerns on this invention.

Explanation of symbols

  1 Shoe sole, 2 Rubber parts, 3 Base parts, 4a, 4b, 4c Rubber part material, 5 Rubber parts molding die, 6,8 Recess, 7 Injection mold for shoe sole.

Claims (7)

  A method for producing a shoe sole, wherein the rubber part and the thermoplastic resin are crosslinked and bonded by overmolding a thermoplastic resin to a rubber part that is at least partially cross-linked in advance.   2. The method for manufacturing a shoe sole according to claim 1, wherein the overmolding is performed by injection molding.   The method for manufacturing a shoe sole according to claim 1, wherein the rubber part is peroxide-crosslinked.   The method for manufacturing a shoe sole according to any one of claims 1 to 3, wherein the rubber part includes a resin highly compatible with the thermoplastic resin.   The thermoplastic resin and the resin highly compatible with the thermoplastic resin include one or more compounds selected from the group consisting of polyamide resins, polyamide elastomers, polyurethane resins, and polyurethane elastomers. A method for manufacturing shoe soles.   The method for producing a shoe sole according to any one of claims 1 to 5, wherein the rubber component of the rubber part contains 40% by mass or more of carboxylated acrylonitrile-butadiene rubber.   The shoe sole manufactured using the manufacturing method of the shoe sole in any one of Claims 1-6.

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