JP3341660B2 - Synthetic resin shoe sole and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shoe sole made of synthetic resin, generally called a compression sole, and to a method of manufacturing the shoe sole. More specifically, the present invention relates to a shoe sole improved so that both the elasticity of the compression sole (particularly the maintenance of elasticity over time) and the shaping of the design are satisfactory.

[0002]

2. Description of the Related Art Conventionally, a compression sole of this kind is generally provided by placing a foamed resin composition of ethylene-vinyl acetate copolymer (EVA) cut into a substantially sole shape in a molding die. Increased temperature (about 150
C), the resin compound is softened and flowed by applying a pressure higher than the upper pressure to form the upper part of the shoe sole (conventionally called a midsole). , Made by laminating and adhering to a lower sole (comprising a rubber or elastomer compound) having a ground plane. Thus, the upper bottom (conventional midsole) formed by this method is usually an integrally formed product having a rising portion on a part of the outer peripheral edge thereof, and the surface of the outer peripheral side surface including the rising portion is usually formed. Has a design on the side of the shoe sole.

[0003]

By the way, such a compression sole generally has, for example, whether it has sufficient elasticity (cushioning property) as a shoe sole, in particular, its elasticity decreases with time, so-called "hetari". (Whether elasticity is maintained over time), and whether wrinkles or chips are formed on the outer peripheral side of the shoe sole, that is, whether the desired design is accurately formed on that side. Properties such as (designability of design) are regarded as important in quality evaluation. In the field, in order to be able to maintain satisfactory elasticity, the compression sole, particularly the upper bottom, is softer and more elastic, and is more preferable. It is said that the harder the upper bottom is, the harder it is deformed, the more preferable. However, the conventional compression sole has an upper bottom made of an integrally molded product of an EVA foamed resin composition and has the same physical properties throughout, so that two contradictory properties (that is, elasticity and formability of the design) are contradictory. In both cases, it was difficult to satisfy the required standards and make them satisfactory. In recent years, in the production of shoes and shoe parts, it is required to adopt a production method more suitable for a high-mix low-volume production system, like other industrial products. Accordingly, there has been a demand for the production of compression soles to be improved to be suitable for such production modes.

The present invention has been made on the basis of the above-mentioned backgrounds, and its object is to provide a shoe sole having good and satisfactory elasticity of a shoe sole and good shaping of a design, and a higher quality. Sole made of synthetic resin (compression sole)
Is to provide. Another object of the present invention is to provide an economical method for manufacturing the shoe sole of the present invention, which can reliably manufacture the synthetic resin shoe sole of the present invention and is suitable for a high-mix low-volume production system. . Other objects, effects and advantages of the present invention will be derived from the following description, and from the claims.

The inventor of the present invention believes that the elasticity of the shoe sole is particularly problematic in the central portion of the upper sole (midsole), whereas the shapeability of the design is problematic in other cases. Focusing on the fact that it is a peripheral part, we conducted intensive research, and as a result,
By dividing the upper sole of the shoe sole into a soft and resilient member at the center of the midsole and a hard and hardly deformable member at the outer peripheral edge of the midsole, both members are made of ethylene- It consists of a foamed resin compound of vinyl acetate copolymer, but by making each one of them different in physical properties, it is possible to obtain good synthetic resin shoe soles with good elasticity and design shapeability. Find out,
As a result of further research, the two members constituting the midsole have a hardness (measured by a spring-type hardness test (A type) defined in JIS K6301).
The hardness of the member at the center of the midsole is 5 to 30 degrees lower than the hardness of the member at the outer peripheral edge of the midsole. One member has a density of 0.1 g / cm
A member having a density of ³ to 0.3 g / cm ³ and a density difference of 0.02 g / cm ³ to 0.20 g / cm ^{3 at the} center of the midsole which is greater than the density of the member at the outer peripheral edge of the midsole. It has been found that when the value is lower than ³ , both the elasticity and the shaping of the design are particularly good, and the present invention has been completed.

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides
Specifically, in a synthetic resin shoe sole obtained by laminating and bonding an upper bottom made of a foamed resin composition of an ethylene-vinyl acetate copolymer to a lower bottom having a grounding surface made of a rubber compound or an elastomer compound, Top bottom is inside the molding die
Place the tape member and midsole member on the
By doing so, the tape member is fused and integrated to the outer peripheral side surface of the midsole member and attached to at least a part of the periphery thereof, and the tape member and the midsole member are both ethylene-vinyl acetate copolymer. The present invention relates to a synthetic resin shoe sole, which is a united foamed resin composition, each of which has different physical properties. In a more preferred aspect of the present invention, the tape member and the midsole member have a hardness (JIS K6).
A member having a hardness of 30 to 60 degrees (measured by a spring hardness test (A type) specified in 301), and the hardness of the midsole member is 5 to 30 degrees different from the hardness of the tape member. Only lower and also
The tape member and the midsole member have a density of 0.
A member having a density of 1 g / cm ³ to 0.3 g / cm ³ , wherein the density of the midsole member is 0.02 g / cm ³ to 0.20 more than the density of the tape member.
g / cm ³ for the above synthetic resin shoe sole where lower only.

In the present invention, the upper sole (midsole) of the sole consists of two members, a midsole member at the center of the sole and a tape member at the outer peripheral edge of the sole. It is adhered or fused to the outer peripheral side surface, and is attached to all or a part of the periphery thereof (usually at the periphery of the heel). Both the midsole member and the tape member are made of an ethylene-vinyl acetate copolymer (EVA) foamed resin compound, but have different physical properties, particularly hardness and density. The midsole member and the tape member according to the present invention have a hardness of 30 to 60 degrees and a hardness of 0.1 g in order to provide performance such as strength, flexibility and comfort required for a shoe sole, particularly for a compression sole.
/ Cm ³ to 0.3 g / cm ³ each.
Therefore, when the hardness and density are outside the above ranges, the resulting sole does not have the required performance of the compression sole. Note that this hardness is based on JIS K
It is measured by a spring hardness test (A type) specified in 6301. When referred to herein as hardness without special notice, it means the hardness measured in this hardness test. In addition, the midsole member comprises a softer, more resilient EVA foamed resin formulation, while the tape member comprises a stiffer, less deformable EVA foamed resin formulation. In particular, preferably, the hardness of the midsole member is 5 to 30 degrees lower than the hardness of the tape member, and the density of the midsole member is 0.02% less than the density of the tape member.
The composition and properties of the EVA foamed resin formulation used for each component are selected to be less than g / cm ³ to 0.20 g / cm ³ . Hardness difference is 5
When the degree is less than the degree, and when the density difference is less than 0.02 g / cm ³ , the obtained sole has sufficient elasticity (cushioning property), but the outer peripheral side surface of the sole has formed wrinkles or chips. Are found in some places, resulting in inferior formability of the design, or molded wrinkles or chips are hardly seen on the outer peripheral side of the shoe sole, but have poor elasticity, and have elasticity over a long period of use. And so-called settling is likely to occur, resulting in unsatisfactory performance comparable to that of a conventional compression sole.

Further, the present invention provides a method of manufacturing the above-mentioned synthetic resin shoe sole (compression sole), that is, a method of forming a temporarily foamed midsole member in the form of a plate on an upper bottom forming die. A first step of cutting into a shape corresponding to the shape and smaller than the size of the inner periphery of the mold, and then placing the produced midsole member in the molding die, and a temporarily foamed tape member And cutting the formed tape member into the molding die, the inner peripheral surface of the die and the midsole member in the die. A second step of adhering the tape member to the outer peripheral side surface of the midsole member, if necessary, and then sealing the molding die and subsequently applying heat and pressure, thereby forming the inside of the die. Material is softened and fluidized, and at the same time both parts are completely foamed A third step of cooling the molding die and removing the molded upper bottom, and laminating and bonding the produced upper bottom to a lower bottom having a ground plane; The present invention relates to a method for manufacturing a synthetic resin shoe sole, comprising a fourth step of making a shoe sole. This manufacturing method consists of two members, a midsole member and a tape member, each of which is separately manufactured and processed on the upper sole (midsole). It has the advantage that it can be handled by a mold, the applicable width (degree of freedom) of each molding die is further increased, and it can be more conveniently adapted to a multi-product small-quantity production system for shoe soles. Moreover, if the required number of molding dies can be reduced by the present method, equipment costs can be reduced and more economical production can be achieved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One preferred embodiment of the present invention will be described with reference to the accompanying drawings. The synthetic resin shoe sole of this embodiment is a compression sole,
As shown in FIG. 1, an upper bottom (midsole) 1 is laminated and bonded to a lower bottom (outsole) 2 having a ground plane, and the upper bottom 1 is a foamed resin of an ethylene-vinyl acetate copolymer. The lower sole 2 consists of a rubber compound or an elastomer compound. This upper bottom 1
As shown in FIG. 2, it consists of two members of the tape member 4 of the midsole member 3 and the midsole outer peripheral edge of the midsole central, outer peripheral sides of the strip-shaped tape member 4 midsole member 3 shown in FIG. 3 And is attached to the peripheral edge portion including the heel portion in a rising form.
The midsole member 3 and the tape member 4 are both foamed resin compounds of an ethylene-vinyl acetate copolymer,
Each of these properties is different from each other. In particular,
The midsole member 3 and the tape member 4 are members having a hardness of 30 to 60 degrees, and the hardness of the midsole member 3 is different from the hardness of the tape member 4 by a hardness difference of 5 degrees.
And lower by only 30 to 30 degrees, and the two members 3 and 4 have a density of 0.1 g / cm ³ to 0.1 g / cm ³ .
A member having a density of ³ g / cm ³ , and the density of the midsole member 3 is lower than the density of the tape member 4 by a density difference of 0.02 g / cm ³ to 0.20 g / cm ³ . . Although not shown in detail, the shoe sole according to this embodiment includes, as a first step, the provisional foamed plate material of the midsole member, which is formed on the molding surface of the molding die for the upper sole 1. Cut into a shape corresponding to the shape and smaller than the size of the inner circumference of the mold, and then place the produced midsole member 3 in a molding die, and as a second step, temporarily foamed tape The strip material of the member is cut into a shape corresponding to the outer shape of the tape member 4, and then the tape member 4 is placed in a molding die, and the inner peripheral surface of the die and the midsole member in the die. 3 and, if necessary, the tape member 4 is adhered to the outer peripheral side surface of the midsole member 3. Then, as a third step, the molding die is sealed and then, for example, under a high pressure of 150 to 1.
By heating and pressurizing at 60 ° C. for 10 to 15 minutes, the material in the mold is softened and fluidized, and at the same time, both members 3 and 4 are completely foamed and fused and integrated. 8 to 1 until the temperature drops to 30 to 40 ° C.
After cooling for 2 minutes, the formed upper bottom 1 is taken out, and as a fourth step, the formed upper bottom 1 is subjected to buffing processing if necessary, and then the lower bottom 2 (manufactured separately).
It can be made by laminating and bonding. Thereafter, the sneaker shoe 5 is completed by bonding the manufactured shoe sole to the upper 6 suspended from the last mold.

[0010]

EXAMPLES Further, examples of the present invention will be described together with comparative examples. Midsole member 3 having the composition shown in the following table
Using the tape member 4 and the tape member 4, the upper sole 1 was formed by the same procedure as in the above embodiment, and the shoe sole of each example was finished by laminating and bonding with the lower sole 2. All of the lower bottoms 2 used in these examples were styrene-butadiene rubber (SBR) blends (specific gravity 1.1).
0). For comparison, a conventional midsole having the composition shown in the following table was also manufactured, and the shoe sole of each comparative example was finished by lamination bonding with a lower sole. The composition of the lower bottom is exactly the same as that of the lower bottom 2 in the embodiment. The specific gravity, hardness, compression set and rebound resilience of each shoe sole were measured, and the measured values were evaluated. The hardness is
Spring hardness test specified in JIS K6301 (A
Shape). Compression set is JIS K6
301 was measured according to the compression set test, and the rebound resilience was measured according to the rebound resilience test specified in JIS K6301. Generally, compression soles have a compression set of 10-20% and a compression set of 3-20%.
A rebound resilience of 5 to 45% is said to be appropriate. In addition, the design of the outer peripheral side surface of the shoe sole of each example was also visually evaluated. The results of these tests and the like are summarized in Table 1 below. In the tables, numerical values indicating the content of each component represent parts by weight.

[0011] Note) EVA stands for ethylene-vinyl acetate copolymer. E
PDM stands for ethylene-propylene-butadiene copolymer. Diene polymer refers to 1,2-polybutadiene. Ca CO ₃ is calcium carbonate, the white powder of which is used. Titanium white is also known as titanium white,
It is a titanium oxide pigment. The blowing agent is n-pentane. Dicumyl peroxide was used for the peroxide. The compression set is measured by a test according to a compression set test (JIS K 6301), and the unit of the measured value is%. The rebound resilience is measured by a test based on a rebound resilience test (JIS K 6301), and the unit of the measured value is%. The evaluation of the formability of the design was performed on the design on the outer peripheral side of the shoe sole (the design on the surface of the tape member), and ◎ in the table indicates that the design was accurately formed as planned, and × Is molding wrinkles,
This indicates that the shaping of the design is not accurate due to chipping. The compression set was evaluated according to the following criteria: と き when the measured value of the permanent compression set was 10 to 20%, and × when the measured value was out of the range. The rebound resilience was evaluated on the basis of ◎ when the measured value of the rebound resilience was 35 to 45% and X when the measured value was out of the range.

According to this table, the midsole member and the tape member have a hardness of 30 to 60 degrees, and the hardness of the midsole member is lower than the hardness of the tape member by a hardness difference of 5 to 30 degrees. And these two members have a density of 0.1 g / cm ³ to 0.3 g /
cm ³ , and the density of the midsole member is 0.02 g / c more than the density of the tape member.
When it is lower than m ³ to 0.20 g / cm ³ , both the elasticity of the sole and the shaping of the design are found to be particularly good and satisfactory.

[0013]

As described above, according to the present invention,
Both the elasticity of the shoe sole and the shaping property of the design are satisfactory and satisfactory, and the effect is obtained that the shoe sole (compression sole) has higher quality. Further, according to the manufacturing method of the present invention, such a high-quality shoe sole can be reliably manufactured, and moreover, an effect that it is more suitable for a multi-product small-quantity production system can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a sneaker shoe provided with a shoe sole according to one embodiment of the present invention.

FIG. 2 is a perspective view showing an upper portion of the sole shown in FIG. 1, that is, an upper sole;

FIG. 3 is a plan view showing a tape member used for an upper bottom of FIG. 2;

[Explanation of symbols]

 1 top bottom 2 bottom bottom 3 midsole member 4 tape member 5 sneaker shoes

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) A43B 1/00-23/30 A23D 25/06 A23D 86/00

Claims (3)

(57) [Claims] 1. A synthetic resin shoe sole comprising an upper sole made of a foamed resin composition of an ethylene-vinyl acetate copolymer laminated and bonded to a lower sole having a grounding surface made of a rubber compound or an elastomer compound. The upper bottom is provided with a tape member and a midsaw in a molding die.
By mounting and heating and pressing the tape member , the tape member is fused and integrated with the outer peripheral side surface of the midsole member and attached to at least a part of the periphery thereof, and the tape member and the midsole member are And a synthetic resin shoe sole, each of which is a foamed resin composition of an ethylene-vinyl acetate copolymer, but each of which has different physical properties. 2. The tape member and the midsole member have a hardness of 30 degrees to 60 degrees (measured by a spring type hardness test (A type) specified in JIS K6301).
And the hardness of the midsole member is lower than that of the tape member by a hardness difference of 5 to 30 degrees, and the tape member and the midsole member have a density of 0.1 g / g. cm ³ to 0.3 g / c
m ³ , and the density of the midsole member is 0.02 g / density difference from the density of the tape member.
It cm ³ not, characterized in that less than only 0.20 g / cm ^3, claim 1 synthetic resin shoe sole as set forth. 3. The method of manufacturing a synthetic resin shoe sole according to claim 1, wherein the temporarily foamed midsole member is shaped into a shape of a molding surface of an upper bottom molding die. A first step of cutting the corresponding midsole member into the corresponding molding die, and then cutting the formed midsole member into the molding die; and forming a belt shape of the temporarily foamed tape member. The shaped material is cut into a shape corresponding to the outer shape of the tape member, and then the formed tape member is inserted into the molding die with the inner peripheral surface of the die and the midsole member in the die. A second step of disposing the tape member to the outer peripheral side surface of the midsole member, if necessary, and then sealing the molding die and then applying heat and pressure to form a material in the die. Is softened and fluidized, and at the same time, both the above members are completely foamed and fused and integrated. A third step of cooling the molding die and removing the molded upper sole; and a fourth step of laminating and bonding the produced upper sole to a lower sole having a ground contact surface to form a shoe sole. A method for producing a synthetic resin shoe sole, comprising the steps of: