Shoe outsole

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to outsoles for tennis shoes, golf shoes, soccer shoes, jogging shoes, trekking shoes, town shoes and the like.

[0003] 2. Description of the Related Art

[0004] A shoe comprises an outsole forming a bottom surface thereof. An important performance required for the outsole includes an excellent gripping property, an excellent abrasion resistance and a proper flexibility. In order to achieve the required characteristics, the outsole is formed of rubber or synthetic resin.

[0005] In respect of an enhancement in design, the outsole is comparted into a plurality of regions having different colors from each other in some cases. A mold 51 to be used for manufacturing the outsole is shown in FIG. 8. FIG. 8 is a sectional view taken along a line in the axial direction of a shoe. In this manufacturing method, first of all, a portion corresponding to a stud of the outsole is filled with a first rubber composition 53 as shown in FIG. 8(a). In FIG. 8(a), a blacked portion indicates the first rubber composition 53.

[0006] Next, mold clamping is carried out and the mold 51 is heated. Consequently, the first rubber composition 53 is fluidized and the rubber composition 53 leaks out of a portion corresponding to a stud as shown in FIG. 8(b). The leaking portion (spew) is removed by a worker. FIG. 8(c) shows a state obtained after the spew is removed. Next, a second rubber composition is put in the mold 51 and is mold clamped so that the mold 51 is heated. The second rubber composition has a different color from that of the first rubber composition 51. By the mold clamping, a stud 55 formed of the first rubber composition 51 and a body 57 formed of the second rubber composition are bonded to each other and are thus integrated as shown in FIG. 8(d). Consequently, an outsole comprising a plurality of regions having different colors from each other is finished. In some cases, three or more kinds of rubber compositions having different colors from each other are sequentially put in the mold 51.

[0007] In such a manufacturing method, the work for filling a rubber composition and the work for removing a spew are to be carried out almost manually, which is inefficient. In addition, when the second rubber composition is to be heated and pressurized, the first rubber composition is fluidized to some extent. By the fluidization, a boundary of the first rubber composition and the second rubber composition is ambiguous so that the appearance of the outsole is deteriorated.

[0008] When only the first rubber composition is to be heated, the vulcanization of the first rubber composition is promoted if a heating temperature is raised or a time taken for heating is increased. Accordingly, the first rubber composition in a second heating operation is prevented from being fluidized. However, the first rubber composition which has increasingly been vulcanized is bonded to the second rubber composition with difficulty. In addition, the first rubber composition is excessively vulcanized by the second heating work so that a thermal deterioration is caused. In particular, in the case in which at least three kinds of rubber compositions are to be sequentially filled, there is a remarkable problem in that defective bonding and a thermal deterioration are caused.

[0009] The same problems also arise in the case in which rubber compositions formed of different materials from each other are used. For example, in the manufacture of the outsole comprising a region in which rubber having an excellent gripping property is used as a base material and a region in which a rubber having an excellent abrasion resistance is used as a base material, there is a problem in that the boundary becomes ambiguous due to the fluidization and the defective bonding and the thermal deterioration are caused. Furthermore, there is also a combination of materials having insufficient bonding strengths due to vulcanization.

SUMMARY OF THE INVENTION

[0010] The present invention provides a method of manufacturing an outsole comprising the steps of:

[0011] putting a first polymer composition in a piece forming mold and forming a piece; and

[0012] putting, in a final mold, a second polymer composition for a body having a different material or color from that of the first polymer composition and a piece obtained at the piece forming step and bonding the body to the piece. In the manufacturing method, a piece is molded by a different mold from a mold used for molding the body. Therefore, the polymer composition can easily be filled and the removal of a spew does not take time and labor.

[0013] In the case in which the piece and the body are formed of a rubber composition, it is preferable that the piece should be brought into a semivulcanization state at the piece forming step. At a bonding step, the body and the piece are bonded by vulcanization. Consequently, a bonding strength is increased. The rubber composition for the body which is put in the final mold may be set in an unvulcanization state or a semivulcanization state. By setting the semivulcanization state, the fluidization of a rubber can be more suppressed.

[0014] An outsole according to the present invention comprises a body and a piece to be bonded to the body with an adhesive. The body and the piece have different materials or colors. In the outsole, the body and the part are formed separately. Therefore, a polymer composition can easily be filled, and furthermore, the removal of a spew does not take time and labor. In addition, the boundary between the body and the piece is obvious.

[0015] The bonding using an adhesive is effective in the case in which a rubber composition using, as a base rubber, an acrylonitrile-butadiene copolymer (NBR) which is bonded by vulcanization with difficulty is utilized for one of the body and the piece. In particular, the same bonding is effective in the case in which one of the body and the piece is the acrylonitrile-butadiene copolymer and the other is a styrene-butadiene copolymer (SBR) or polybutadiene (BR).

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]
FIG. 1 is a partially sectional view showing a cut-away shoe according to an embodiment of the present invention,

[0017]
FIG. 2 is a bottom view showing a shoe outsole in FIG. 1,

[0018]
FIG. 3(a) is a bottom view showing a first piece to be used for the outsole in FIG. 2,

[0019]
FIG. 3(b) is a sectional view taken along a line A-A in FIG. 3(a),

[0020]
FIG. 4(a) is a bottom view showing a second piece to be used for the outsole in FIG. 2,

[0021]
FIG. 4(b) is a sectional view taken along a line B-B in FIG. 4(a),

[0022]
FIG. 5(a) is a bottom view showing a third piece to be used for the outsole in FIG. 2,

[0023]
FIG. 5(b) is a sectional view taken along a line C-C in FIG. 5(a),

[0024]
FIG. 6 is a typical view showing a state of molding in a final mold,

[0025]
FIG. 7 is a typical sectional view showing an outsole formed by the final mold in FIG. 6, and

[0026]
FIG. 8 is a typical view showing a state in which a conventional outsole is molded.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The present invention will be described below in detail based on a preferred embodiment with reference to the drawings.

[0028] A shoe 1 in FIG. 1 comprises an upper 2, an insole 3, a midsole 4, and an outsole 5. The material, shape and dimension of the upper 2 are the same as those of the upper of a well-known shoe. The material, shape and dimension of the midsole 3 are the same as those of the insole of the well-known shoe. The material, shape and dimension of the midsole 4 are the same as those of the midsole of the well-known shoe. The insole 3 and the midsole 4 may be omitted.

[0029]
FIG. 2 is a bottom view showing the outsole 5 of the shoe 1 in FIG. 1. The outsole 5 is formed of a vulcanized rubber. As will be described below in detail, the outsole 5 includes a body and three pieces. FIG. 2 shows only the outsole 5 for a left foot, and an outsole for a right foot has a shape which is obtained by inverting the shape shown in FIG. 2.

[0030]
FIG. 3 shows a first piece 6 to be used for the outsole 5 in FIG. 2. FIG. 3(a) is a bottom view and FIG. 3(b) is a sectional view taken along a line A-A in FIG. 3(a). The first piece 6 is almost plate-shaped. The first piece 6 includes a large number of through holes 7. The first piece 6 has a silver color.

[0031]
FIG. 4 shows a second piece 8 to be used for the outsole 5 in FIG. 2. FIG. 4(a) is a bottom view and FIG. 4(b) is a sectional view taken along a line B-B in FIG. 4(a). The second piece 8 is almost annular. The second piece 8 includes a large number of projections 9. The second piece 8 has an orange color.

[0032]
FIG. 5 shows a third piece 10 to be used for the outsole 5 in FIG. 2. FIG. 5(a) is a bottom view and FIG. 5(b) is a sectional view taken along a line C-C in FIG. 5(a). The third piece 10 is almost annular. The third piece 10 also includes a large number of projections 9 in the same manner as the second piece 8. The third piece 10 has an orange color.

[0033] In the manufacture of the outsole 5, first of all, the first piece 6 is molded. In the molding, a rubber composition is put in a mold and is heated and pressurized. By the heating, the rubber composition is vulcanized. In this case, a heating temperature is set to be low or a time taken for heating is shortened so that the first piece 6 in a semivulcanization state is obtained. Another mold is used to obtain the second piece 8 and the third piece 10 in the semivulcanization state in the same manner as the first piece 6.

[0034] Next, a final mold 11 is prepared as shown in FIG. 6, and the first piece 6, the second piece 8 and the third piece 10 are put in the final mold 11. In the putting operation, the projections 9 in the second piece 8 and the third piece 10 penetrate through the holes 7 of the first piece 6. Then, the rubber composition 12 for a body is put in the final mold 11. The rubber composition 12 has a black color. Thereafter, the final mold 11 is clamped and a temperature is raised. Consequently, the pieces 6, 8 and 10 and the rubber composition 12 are vulcanized so that the outsole 5 is finished.

[0035]
FIG. 7 is a typical sectional view showing the outsole 5 formed by the final mold 11 in FIG. 6. The outsole 5 includes the first piece 6, the second piece 8, the third piece 10 and a body 13. The first piece 6 is bonded by vulcanization with the second piece 8 and third piece 10, the second and third pieces 8 and 10 are bonded by vulcanization with the body 13, and the body 13 is bonded by vulcanization with the first piece 6. A great bonding strength is obtained by the vulcanization bonding, and furthermore, a surface treatment (for example, surface polishing) for portions to be bonding objects is not required.

[0036] In the manufacturing method, the pieces 6, 8 and 10 are formed by a different mold from the final mold 11. Therefore, the work for putting a rubber composition and the work for removing a spew do not take time and labor but can be carried out efficiently. The pieces 6, 8 and 10 of the outsole 5 are heated twice by the molds, and the body 13 is heated once by the mold. In other words, any of the portions 6, 8, 10 and 13 in the outsole 5 which is heated most often is heated only twice. In the outsole 5, a thermal deterioration can be prevented from being caused by excessive vulcanization and a high bonding strength can be obtained. In addition, it is possible to promote the vulcanization to some extent in the molding stage of the pieces 6, 8 and 10. Therefore, the rubber composition can be prevented from being fluidized at the bonding step to be carried out by the final mold 11. Accordingly, the boundary of the silver color of the first piece 6, the orange color of the second and third pieces 8 and 10 and the black color of the body 13 is obvious and an excellent appearance can be obtained. The manufacturing method is particularly suitable for the manufacture of the outsole 5 in which the number of the portions 6, 8, 10 and 13 (that is, the sum of the number of the body 13 and the number of the pieces 6, 8 and 10) is three or more.

[0037] The rubber composition 12 to be put in the final mold 11 may be set in the semivulcanization state, that is, it is formed to have a predetermined shape by another mold. Consequently, it is possible to shorten a time taken for the vulcanization in the final mold 11. Moreover, the fluidization of the rubber can be suppressed in the final mold 11 and the boundary between the pieces is more obvious.

[0038] The first piece 6, the second piece 8, the third piece 10 and the body 13 may be separately vulcanized respectively and may be bonded to each other with an adhesive. Also in the case of the bonding using the adhesive, the work can be carried out efficiently and the boundary between the portions 6, 8, 10 and 13 can become obvious. In the bonding of materials which are bonded by vulcanization to each other with difficulty, particularly, the bonding using an adhesive is effective. Such an example includes bonding of a portion formed by a rubber composition using an acrylonitrile-butadiene copolymer as a base rubber and a portion formed by a rubber composition using a styrene-butadiene copolymer as a base rubber, and bonding of a portion formed by a rubber composition using the acrylonitrile-butadiene copolymer as a base rubber and a portion formed by a rubber composition using polybutadiene as a base rubber. By bonding the portions formed of different materials, it is possible to obtain the outsole 5 having both advantages. More specifically, a gripping property can be obtained by the acrylonitrile-butadiene copolymer when the ground is wet, and a strength can be obtained by the styrene-butadiene copolymer or the polybutadiene.

[0039] The vulcanization bonding and the bonding using an adhesive may be carried out together. For example, the first piece 6 may be bonded by vulcanization with the second and third pieces 6 and 8, and the pieces 6, 8 and 10 may be then bonded to the body 13 with an adhesive.

EXAMPLES

[0040] [Preparation of Rubber Composition]

[0041] 100 parts by weight of an acrylonitrile-butadiene copolymer (trade name of “Nipol DN200” produced by Nippon Zeon Co., Ltd.), 45 parts by weight of silica (trade name of “Ultrasil VN3 granule type” produced by Degusa Co., Ltd.), 4.0 parts by weight of a silane coupling agent (trade name of “Si69” produced by Degussa Co., Ltd.), 2.0 parts by weight of dioctylphthalate, 2.0 parts by weight of an antioxidant (trade name of “Nocrac 200” produced by Ouchi Shinko Chemical Industrial Co., Ltd.), 0.5 part by weight of another antioxidant (trade name of “Sunnoc N” produced by Ouchi Shinko Chemical Industrial Co., Ltd.), 3.0 parts by weight of zinc oxide (trade name of “zinc oxide type II” produced by MITSUI MINING & SMELTING CO., LTD.), 1.0 part by weight of stearic acid, 0.5 part by weight of sulfur powder obtained by means of a 200-mesh, 1.3 parts by weight of dibenzothiazyldisulfide to be a vulcanization accelerator (trade name of “Nocceler DM” produced by Ouchi Shinko Chemical Industrial Co., Ltd.), 2.5 parts by weight of tetrakis(2-ethylhexyl)thiuramdisulfide to be another vulcanization accelerator (trade name of “Nocceler TOT-N” produced by Ouchi Shinko Chemical Industrial Co., Ltd.), and a black pigment were kneaded by means of a Banbury mixer and a roll. Thus, a rubber composition N1 was obtained.

[0042] A rubber composition N2 was obtained in the same manner as the rubber composition N1 except that a silver pigment was used in place of the black pigment. Moreover, a rubber composition N3 was obtained in the same manner as the rubber composition N1 except that an orange pigment was used in place of the black pigment.

[0043] 75 parts by weight of a styrene-butadiene copolymer (trade name of “Nipol 1507” produced by Nippon Zeon Co., Ltd.), 25 parts by weight of polybutadiene (trade name of “BR11” produced by JSR Corporation), 60 parts by weight of ISAF carbon black (trade name of “Asahi #80” produced by Asahi Carbon Co., Ltd.), 5.0 parts by weight of process oil (trade name of “Pw380” produced by Idemitsu Kosan Co., Ltd.), 2.0 parts by weight of an antioxidant (trade name of “Nocrac 200” produced by Ouchi Shinko Chemical Industrial Co., Ltd.), 3.0 parts by weight of zinc oxide (trade name of “zinc oxide type II” produced by MITSUI MINING & SMELTING CO., LTD.) and 1.0 part by weight of stearic acid were kneaded by means of the Banbury mixer. Thus, a rubber composition was obtained. The rubber composition was put in an open roll, and 1.5 parts by weight of sulfur, 1.0 part by weight of N-tert-butyl-2-benzothiazolylsulfenamide to be a vulcanization accelerator (trade name of “Nocceler NS” produced by Ouchi Shinko Chemical Industrial Co., Ltd.), 0.5 part by weight of zinc diethylthiocarbamate to be another vulcanization accelerator (trade name of “Nocceler EZ” produced by Ouchi Shinko Chemical Industrial Co., Ltd.) and 0.5 part by weight of di-orthotolylguanidine to be a further vulcanization accelerator (trade name of “Nocceler DT” produced by Ouchi Shinko Chemical Industrial Co., Ltd.) were added and kneaded. Thus, a black rubber composition S1 was obtained.

Example 1

[0044] A rubber composition N1 was put in a body mold, and was heated and vulcanized for 10 minutes at 160° C. Thus, a body was obtained. A rubber composition N2 was put in a piece mold, and was heated and vulcanized for 10 minutes at 160° C. Thus, a first piece was obtained. A rubber composition N3 was put in another piece mold, and was heated and vulcanized for 10 minutes at 160° C. Thus, a second piece was obtained. The rubber composition N3 was put in a further piece mold, and was heated and vulcanized for 10 minutes at 160° C. Thus, a third piece was obtained. Then, the body and each piece were bonded to each other with an adhesive. Consequently, an outsole according to an example 1 was obtained.

Example 2

[0045] An outsole according to an example 2 was obtained in the same manner as in the example 1 except that a rubber composition S1 is used in place of the rubber composition N1.

Example 3

[0046] A rubber composition N1 was put in a body mold, and was heated for 5 minutes at 160° C. Thus, a body in a semivulcanization state was obtained. A rubber composition N2 was put in a piece mold, and was heated for 5 minutes at 160° C. Thus, a first piece in the semivulcanization state was obtained. A rubber composition N3 was put in another piece mold, and was heated for 5 minutes at 160° C. Thus, a second piece in the semivulcanization state was obtained. The rubber composition N3 was put in a further piece mold, and was heated for 5 minutes at 160° C. Thus, a third piece in the semivulcanization state was obtained. Then, the body and the first, second and third pieces were put in a final mold and were heated for 5 minutes at 160° C. Consequently, the body and each of the pieces were vulcanized and bonded. At the same time, the first piece and the second and third pieces were vulcanized and bonded. Thus, an outsole according to an example 3 was obtained.

Comparative Example 1

[0047] A part of the final mold was filled with the rubber composition N3 and was heated and pressurized for 20 seconds, and a spew was then removed. Thus, portions corresponding to projections of the second and third pieces were formed. Next, a part of the final mold was filled with the rubber composition N2 and was heated and pressurized for 20 seconds, and the spew was then removed. Thus, a portion corresponding to the first piece was formed. Next, a part of the final mold was filled with the rubber composition N3 and was heated and pressurized for 20 seconds, and the spew was then removed. Thus, a portion corresponding to a part other than the projections of the second and third pieces was formed. Furthermore, the rubber composition N1 was put in the final mold and was heated for 10 minutes at 160° C. Thus, an outsole according to a comparative example 1 was obtained.

Comparative Example 2

[0048] An outsole according to a comparative example 2 was obtained in the same manner as in the comparative example 1 except that a rubber composition S1 was used for the body.

Obviousness of Boundary

[0049] The outsole was observed visually and the obviousness of a boundary between portions having different colors was decided in 10 stages. The most excellent obviousness was set to be “10” and the worst obviousness was set to be “1”. The result is shown in the following table 1.

[0050] [Bonding Strength]

[0051] The first piece of the outsole was held and pulled by means of a nipper and thus tried to be separated from the body. The number of the outsoles which were separated is shown in the following table 1.

[0052] [Gripping Property]

[0053] A well-known upper portion was attached to the outsole to fabricate a shoe. A tester wore the shoe and walked over a wet lawn. The gripping property was decided in 10 stages. The most excellent gripping property was set to be “10” and the worst gripping property was set to be “1”. A mean evaluated point for 10 testers is shown in the following table 1.

1TABLE 1Result of EvaluationExample 1Example 2Example 3Com. Example 1Com. Example 2BodyNBR BaseSBR BaseNBR BaseNBR BaseSBR Base(black color)(N1)(S1)(N1)(N1)(S1)First pieceNBR BaseNBR BaseNBR BaseNBR BaseNBR Base(silver color)(N2)(N2)(N2)(N2)(N2)Second and third PieceNBR BaseNBR BaseNBR BaseNBR BaseNBR Base(orange color)(N3)(N3)(N3)(N3)(N3)Manufacturing methodMolding for eachMolding for eachMolding forPutting in thePutting in thepiecepieceeach piecesame moldsame moldAdhesive bondingAdhesive bondingVulcanizationbondingManufacturing timeShort timeShort timeShort timeLong timeLong timeObviousness of1010 844boundaryBonding strength 881042Gripping property1081010 8

[0054] As shown in the table 1, the outsole according to each of the embodiments gives the excellent evaluation results in all items. From these results, the advantage of the present invention is apparent.

[0055] The above description is only illustrative and various changes can be made without departing from the scope of the present invention.

Shoe outsole

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