Shoe unit soles and shoes equipped with them

Abstract

In shoe unit soles, the aim is to achieve both abrasion resistance and grip, while also stabilizing the mechanical properties of the unit sole. [Solution] The unit sole 2 is composed of a crosslinking foam composition containing a thermoplastic resin including at least a polyolefin elastomer (POE), an ethylene vinyl acetate copolymer (EVA), a crosslinking agent, and a foaming agent. The crosslinking foam composition further contains a silicone resin and ethylene propylene rubber (EPDM).

Description

[Technical Field]

[0001] This disclosure relates to a shoe unit sole and a shoe equipped therewith. [Background technology]

[0002] Conventionally, a composition shown in, for example, Patent Document 1 is known as a material to be applied to a unit sole of a shoe that combines the functions of both the midsole and the outsole.

[0003] Patent Document 1 discloses the use of olefin block copolymers (OBCs) to form shoe midsoles (unit sole foams). Specifically, Patent Document 1 discloses a composition for unit sole foams comprising an olefin multiblock copolymer and a silicone rubber comprising pendant vinyl groups and optionally terminal vinyl groups. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 7227252 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The composition for the unit sole foam described in Patent Document 1 provides particularly excellent abrasion resistance by including the above-mentioned silicone rubber. As a result, when shoes equipped with the unit sole foam are used in indoor sports such as volleyball and basketball, the abrasion resistance of the unit sole is improved in relation to the floor surface in indoor facilities.

[0006] However, in the above-mentioned composition for the unit sole foam, while the inclusion of the aforementioned silicone rubber improved abrasion resistance, it tended to decrease the coefficient of dynamic friction. As a result, when shoes equipped with the above-mentioned unit sole foam were used for indoor sports, sufficient grip could not be obtained in the relationship between the floor surface and the bottom of the unit sole, and the bottom of the unit sole tended to slip against the floor surface. Consequently, when a person wearing the shoes (hereinafter referred to as "wearer") was performing indoor sports, there was a problem in that the wearer could not quickly move to the next action, such as when performing actions like sprinting forward, making a sudden stop backward, or changing direction to the left or right.

[0007] This disclosure has been made in view of the above, and its purpose is to achieve both abrasion resistance and grip in the unit sole of a shoe. [Means for solving the problem]

[0008] To achieve the above objectives, the first disclosure relates to a shoe unit sole, which is composed of a crosslinking foam composition containing a thermoplastic resin including at least a polyolefin elastomer (POE), an ethylene vinyl acetate copolymer (EVA), a crosslinking agent, and a foaming agent. The crosslinking foam composition further contains a silicone resin and ethylene propylene rubber (EPDM).

[0009] In the crosslinked foaming composition according to the first disclosure, the abrasion resistance is improved by the silicone resin. As a result, when shoes equipped with a unit sole are used in indoor sports such as volleyball and basketball, the abrasion resistance of the unit sole is improved in relation to the floor surface in indoor facilities. In particular, the durability of the bottom part of the sole (i.e., the part that comes into contact with the floor surface) is improved. As a result, for example, the deterioration of the sole over time can be suppressed.

[0010] Furthermore, in the crosslinked foaming composition according to the first disclosure, the coefficient of dynamic friction is improved by EPDM. As a result, when shoes equipped with a unit sole are used in indoor sports, the grip between the floor surface and the bottom of the unit sole is improved. This improved grip allows the wearer to quickly transition to the next action when performing indoor sports, for example, when sprinting forward, making a sudden stop backward, or changing direction to the left or right.

[0011] Therefore, the first disclosure makes it possible to achieve both wear resistance and clipping properties.

[0012] In the second disclosure, relating to the first disclosure, in the crosslinked foaming composition, parts by weight of silicone resin (Q) and parts by weight of ethylene propylene rubber (EPDM) (E) satisfy the relationship shown in the following formulas (1) to (4). [Mathematics 1] 0 <Q≦10···(1) [Math 2] 0 <E<20···(2) [Math 3] E+Q≧7.5···(3) [Math 4] EQ ≥ 2.5 ···(4)

[0013] According to this second disclosure, in a cross-linked foaming composition, the region in which both abrasion resistance and grip are achieved in a unit sole is identified when the parts by weight of silicone resin and parts by weight of ethylene propylene rubber (EPDM) satisfy the relationship shown in formulas (1) to (4). This makes it possible to appropriately obtain a shoe unit sole that combines the abrasion resistance exhibited by the incorporation of silicone resin with the grip exhibited by the incorporation of EPDM.

[0014] The third disclosure is a shoe having a unit sole according to the first or second disclosure, wherein the bottom of the unit sole is configured as a contact surface that can be in contact with a floor or road surface.

[0015] According to this third disclosure, in the shoes, the above-described effects (attainment of both wear resistance and clip property) according to the first disclosure or the second disclosure can be obtained.

Advantages of the Invention

[0016] As described above, according to the present disclosure, both wear resistance and clip property can be achieved.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a side view showing a shoe provided with a unit sole according to an embodiment of the present disclosure as viewed from the outer shell side. [Figure 2] FIG. 2 is a graph plotting the improvement rate [%] of the coefficient of kinetic friction in each crosslinked foam A shown in Table 17 with respect to the parts by weight (E) [phr] of EPDM. [Figure 3] FIG. 3 is a graph plotting the improvement rate [%] of the coefficient of kinetic friction in each crosslinked foam B shown in Table 20 with respect to the parts by weight (E) [phr] of EPDM. [Figure 4] FIG. 4 is a graph plotting the improvement rate [%] of the coefficient of kinetic friction in each crosslinked foam C shown in Table 23 with respect to the parts by weight (E) [phr] of EPDM. [Figure 5] FIG. 5 is a graph plotting the compounding ratios in which the parts by weight of EPDM and the parts by weight of silicone resin when it is "〇" in Tables 10, 12, 14 and the parts by weight of EPDM and the parts by weight of silicone resin when it is "〇" or "◎" in Tables 18, 21, 24 overlap each other.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present disclosure will be described in detail based on the drawings. The following description of the embodiments is merely illustrative in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0019] (Shoes) Figure 1 shows the overall shoe 1. The shoe 1 comprises a unit sole 2 and an upper 3 for covering the wearer's foot. Here, the unit sole 2 according to the embodiment of this disclosure is a sole that combines the functions of both a midsole (not shown) and an outsole (not shown) in a typical shoe.

[0020] Shoes 1 can be used as shoes for various sports competitions. In particular, shoes 1 are suitable for indoor sports such as volleyball and basketball. Shoes 1 can also be used as shoes for outdoor sports.

[0021] Note that shoe 1 shown in Figure 1 is an example for the left foot only. Although not shown, the right shoe is symmetrical to the left shoe. In the following explanation, only the left shoe will be described, and the description of the right shoe will be omitted.

[0022] (Unit sole) Unit Sole 2 is composed of a crosslinking foam composition containing a thermoplastic resin, ethylene vinyl acetate copolymer (EVA), a crosslinking agent, and a foaming agent. In other words, Unit Sole 2 is composed of a crosslinked foam obtained by crosslinking and foaming the crosslinking foam composition.

[0023] As shown in Figure 1, the unit sole 2 has a bottom 4. The bottom 4 is configured as a contact surface that can be made in contact with the floor surface of an indoor facility or the road surface outdoors.

[0024] (thermoplastic resin) Examples of the thermoplastic resins mentioned above include polyolefin elastomers (POE), olefin block copolymers (OBC), ethylene vinyl acetate copolymers (EVA), polyamides (PA), polyether block amides (PEBA), and styrene-based thermoplastic elastomers (TPS) (such as styrene-butadiene-butylene-styrene block copolymer (SBBS)).

[0025] Examples of the polyolefin-based elastomers (POEs) mentioned above include α-olefin copolymers. Specific examples of α-olefin copolymers include the registered trademarks "TAFMER DF810" and "TAFMER DF110" manufactured by Mitsui Chemicals, Inc.

[0026] From the viewpoint of easily adjusting the strength and rebound elasticity of the crosslinked foam to an appropriate range, the thermoplastic resin includes at least a polyolefin elastomer (POE). That is, the thermoplastic resin may consist of a single type of polyolefin elastomer (POE), or it may be a combination of two or more types of polyolefin elastomers (POE) and the aforementioned materials other than polyolefin elastomers (POE).

[0027] The content of thermoplastic resin in the crosslinking foam composition is preferably 50% to 99% by mass, and more preferably 70% to 97% by mass. This is because if the content is less than 50% by mass, the viscosity tends to increase due to the large amount of components other than the thermoplastic composition, which can lead to problems such as poor foaming. If the content is greater than 99% by mass, poor foaming can occur due to insufficient foaming agent.

[0028] (Silicone resin) The cross-linked foaming composition contains a silicone resin. The silicone resin has the function of improving abrasion resistance in the unit sole 2 composed of the cross-linked foaming composition.

[0029] A specific example of a silicone resin is "Xiameter RBB-2008-50" (manufactured by DOW Chemical Co., Ltd.) as a silicone rubber. In the crosslinking foam composition, the preferred amount of silicone resin by weight is greater than 0 phr and 10 phr or less (see formula (1) shown in the examples below). More preferably, the amount of silicone resin by weight is 2.5 phr or more and 7.5 phr or less (see formula (5) shown in the examples below).

[0030] (Ethylene propylene rubber) The crosslinked foaming composition contains ethylene propylene rubber (EPDM). In the unit sole 2 composed of the crosslinked foaming composition, ethylene propylene rubber (EPDM) has the function of improving grip (improving the coefficient of dynamic friction).

[0031] A specific example of ethylene propylene rubber (EPDM) is "NORDEL 5565" (manufactured by DOW Chemical). In the crosslinked foaming composition, the preferred amount of EPDM by weight is greater than 0 phr and less than 20 phr (see formula (2) shown in the examples below). More preferably, the amount of EPDM by weight is 5 phr or more and 10 phr or less (see formula (6) shown in the examples below).

[0032] In the crosslinked foaming composition, preferably, the sum of the parts by weight of silicone resin and the parts by weight of EPDM is 7.5 phr or more (see formula (3) shown in the examples described later), and the difference between the parts by weight of silicone resin and the parts by weight of EPDM is 2.5 phr or more (see formula (4) shown in the examples described later).

[0033] (Crosslinking agent) The crosslinking agent is not particularly limited, and sulfur, which is a common crosslinking agent for crosslinking foam compositions, and organic peroxides that promote peroxide crosslinking can be used. Examples of organic peroxides include dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexine-3, 1,3-bis(t-butylperoxyisopropyl)benzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(t-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylperoxybenzoate, t-butylperbenzoate, t-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and t-butylcumyl peroxide. These can be used individually or in combination of two or more types.

[0034] Furthermore, the crosslinking agent content in the crosslinking foam composition is preferably 0.1% to 3.0% by mass, and more preferably 0.3% to 1.0% by mass, relative to the total amount of the crosslinking foam composition. This is because if the content is less than 0.1% by mass, the crosslinking reaction may be insufficient, resulting in poor foaming and a decrease in rebound elasticity. Conversely, if the content is greater than 3.0% by mass, excessive crosslinking may occur, resulting in insufficient foaming.

[0035] (Foaming agent) The foaming agent is not particularly limited as long as it generates the gas necessary to foam the crosslinking foaming composition when heated. More specifically, examples include N,N'-dinitrosopentamethylenetetramine, 4,4'-oxybis(benzenesulfonylhydrazide), azodicarbonamide, sodium bicarbonate, sodium sodium bicarbonate, ammonium bicarbonate, sodium carbonate, ammonium carbonate, azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DNPT), azobisisobutyronitrile, barium azodicarboxylate, and p,p'-oxybisbenzenesulfonylhydrazine (OBSH). These can be used individually or in combination of two or more.

[0036] Furthermore, the foaming agent content in the cross-linked foaming composition is preferably 1.0% to 15% by mass, and more preferably 1.5% to 10% by mass, relative to the total amount of the cross-linked foaming composition. This is because if the content is less than 1.0% by mass, stable foaming may not occur, and if it is greater than 15% by mass, over-foaming may cause variations in the diameter of foam cells on the surface and inside.

[0037] Furthermore, a crosslinked foam can be obtained by adding a crosslinking aid, a foaming aid, etc., to the crosslinked foam composition according to the embodiment of this disclosure and performing crosslinked foaming under predetermined conditions.

[0038] (Cross-linking agent) The crosslinking aids are not particularly limited and include, for example, divinylbenzene, trimethylolpropane trimethacrylate, 1,6-hexanediol methacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol methacrylate, trimellitic acid trialyl ester, trialyl isocyanurate, neopentyl glycol dimethacrylate, 1,2,4-benzenetricarboxylic acid trialyl ester, tricyclodecane dimethacrylate, polyethylene glycol diacrylate, etc. These can be used individually or in combination of two or more.

[0039] Furthermore, the content of the crosslinking aid in the crosslinking foam composition is preferably 0.01% to 5% by mass, and more preferably 0.1% to 1% by mass, relative to the total amount of the crosslinking foam composition. This is because if the content is less than 0.01% by mass, crosslinking may not proceed sufficiently, resulting in a decrease in rebound elasticity. Also, if the content is greater than 5% by mass, the specific gravity of the crosslinking foam composition increases, making it difficult to lighten the product.

[0040] (Foaming agent) There is no particular limit to the foaming agent; for example, urea compounds and zinc compounds such as zinc oxide can be used. These can be used individually or in combination of two or more.

[0041] Furthermore, the foaming agent content in the cross-linked foaming composition is preferably 0.1% to 10% by mass, and more preferably 0.5% to 8.5% by mass, relative to the total amount of the cross-linked foaming composition. It is standard practice to add the foaming agent in an equal amount to the foaming agent. However, if the amount of foaming agent added is less than that of the foaming agent, some foaming agents may release formaldehyde, etc., so appropriate adjustments are necessary depending on the amount of foaming agent added.

[0042] (Method for manufacturing cross-linked foam) Next, a method for producing a crosslinked foam using the crosslinked foam composition according to the embodiments of this disclosure will be described. The method for producing a crosslinked foam comprises a kneading step for preparing the crosslinked foam composition and a foam molding step for foaming the crosslinked foam composition and molding it into a desired shape.

[0043] (Mixing process) First, various raw materials such as thermoplastic resin, fatty acids, fatty acid esters, silicone resin, ethylene propylene rubber (EPDM), crosslinking agents, and foaming agents are put into a kneader and mixed to produce a crosslinking foam composition.

[0044] Here, mixing machines such as mixing rolls, calender rolls, Banbury mixers, and kneaders can be used.

[0045] Then, for example, thermoplastic resin, silicone resin, ethylene propylene rubber (EPDM), fatty acids, fatty acid esters, crosslinking aids, crosslinking agents, foaming aids, and foaming agents are added to a roll set to a predetermined temperature (for example, a surface temperature of 100-120°C) and kneaded, after which pre-molding such as sheeting or pelletizing is performed.

[0046] Alternatively, the process may be carried out in stages using multiple kneaders. For example, thermoplastic resin, silicone resin, ethylene propylene rubber (EPDM), fatty acid, fatty acid ester, and foaming aid may be put into a kneader and kneaded, then the kneaded composition may be moved to a roll, and a crosslinking agent and foaming agent may be added to the roll and kneaded, followed by pre-molding such as sheeting or pelletizing.

[0047] (Foam molding process) Next, the cross-linked foaming composition obtained in the kneading process is filled into a mold and subjected to a heat treatment to promote foaming by the foaming agent. After that, a molding process and a release process are performed to produce a cross-linked foam having the desired shape.

[0048] The heating temperature during the heat treatment will vary depending on the type of foaming agent and foaming aid, but the heat treatment should be performed at a temperature above the decomposition temperature of the foaming agent used (for example, 120-180°C). Alternatively, the crosslinking foaming composition may be filled into a mold and heat treated under pressure, or it may be heated at atmospheric pressure to promote the decomposition of the foaming agent.

[0049] As described above, a crosslinked foam according to the embodiment of this disclosure can be manufactured.

[0050] [Effects of the Embodiment] In embodiments of this disclosure, the unit sole 2 is composed of a crosslinking foam composition containing a thermoplastic resin including at least a polyolefin elastomer (POE), an ethylene vinyl acetate copolymer (EVA), a crosslinking agent, and a foaming agent. The crosslinking foam composition further contains a silicone resin and ethylene propylene rubber (EPDM). In such a crosslinking foam composition, the abrasion resistance exhibited by the silicone resin is improved, and the coefficient of dynamic friction exhibited by the EPDM is improved.

[0051] Specifically, the crosslinked foaming composition according to the embodiment of this disclosure has, firstly, improved abrasion resistance due to the silicone resin. As a result, when the shoe 1 equipped with the unit sole 2 is used for indoor sports such as volleyball and basketball, the abrasion resistance of the unit sole 2 in relation to the floor surface in indoor facilities is improved. In particular, the durability of the bottom portion (the part that contacts the floor surface) of the unit sole 2 is improved. As a result, for example, deterioration of the sole 2 over time can be suppressed.

[0052] Furthermore, a second feature of the crosslinked foaming composition according to the embodiment of this disclosure is that the coefficient of dynamic friction is improved by EPDM. As a result, when the shoe 1 equipped with the unit sole 2 is used for indoor sports, the grip between the floor surface and the bottom of the unit sole 2 is improved. This improved grip allows the wearer to quickly move to the next action when performing indoor sports, for example, when sprinting forward, making a sudden stop backward, or changing direction to the left or right.

[0053] Therefore, the unit sole 2, which is composed of the crosslinked foaming composition according to the embodiment of this disclosure, can achieve both abrasion resistance and gripping properties.

[0054] Furthermore, the crosslinked foam composition, due to the first and second features described above, makes it possible to achieve both abrasion resistance and grip with a single unit sole 2. As a result, the unit sole 2 made of the crosslinked foam composition does not require an outsole, which is typically provided on general shoes (i.e., a sole different from the unit sole 2 shown in Figure 1). In addition, the unit sole 2 made of the crosslinked foam composition according to the embodiment of this disclosure does not require the process of bonding the outsole and midsole in the general shoes described above during the manufacturing process of the unit sole 2. Furthermore, the unit sole 2 made of the crosslinked foam composition according to this embodiment can also be made lighter.

[0055] Preferably, in the crosslinked foaming composition, the parts by weight of silicone resin (Q) and the parts by weight of ethylene propylene rubber (EPDM) (E) satisfy the relationship shown in the following formulas (1) to (4). [Mathematics 1] 0 <Q≦10···(1) [Math 2] 0 <E<20···(2) [Math 3] E+Q≧7.5···(3) [Math 4] EQ ≥ 2.5 ···(4)

[0056] In the crosslinked foaming composition, the region in the unit sole 2 that achieves both abrasion resistance and grip is identified when the weight of the silicone resin and the weight of the ethylene propylene rubber (EPDM) satisfy the relationship shown in formulas (1) to (4). This makes it possible to appropriately obtain a unit sole 2 that achieves both abrasion resistance due to the incorporation of silicone resin and grip due to the incorporation of EPDM.

[0057] Furthermore, the bottom portion 4 of the unit sole 2 is configured as a contact surface that can make contact with the floor surface of an indoor facility or the road surface outdoors. With this configuration, the shoe 1 can obtain the above-mentioned effects of the unit sole 2 (achieving both abrasion resistance and gripping ability).

[0058] While embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of this disclosure. [Examples]

[0059] The present disclosure will be described below based on examples. However, the present disclosure is not limited to these examples, and these examples may be modified or altered in accordance with the spirit of the present disclosure, and such modifications do not exclude them from the scope of the present disclosure.

[0060] (Examples 1-27 and Comparative Examples 1-38) <Manufacturing of cross-linked foams> The cross-linked foams of Examples 1-27 and Comparative Examples 1-38, having the compositions shown in Tables 1-6, were manufactured by the following production method.

[0061] (Mixing process) A crosslinking foaming composition was prepared by adding the thermoplastic resins 1 and 2 (α-olefin copolymer), thermoplastic resin 3 (ethylene vinyl acetate copolymer (EVA)), silicone rubber (silicone resin), ethylene propylene rubber (EPDM), zinc oxide 1 and 2 (foaming aid), fatty acids, fatty acid esters, crosslinking aids, and foaming aids shown in Tables 1 to 6 to a 10-inch open roll (temperature: 110-120°C), kneading the raw materials for 10 minutes, and then adding the crosslinking agent and foaming agent shown in Tables 1 to 6, respectively, and kneading the raw materials for another 10 minutes.

[0062] In addition, the amount of thermoplastic resin 3 (see Table 7), which corresponds to ethylene vinyl acetate copolymer (EVA) as shown in Tables 1 to 6, was set to 30 phr in all of Examples 1 to 27 and Comparative Examples 1 to 38.

[0063] (Foam molding process) 345 g of the prepared cross-linked foaming composition was filled into a mold (length: 175 mm, width: 155 mm, height: 12.5 mm), and press-molded at 175°C and 20 MPa until uniform foaming occurred throughout to obtain a primary foam. Next, the primary foam was cut to a predetermined size, and compression was started at 175°C until the height of the cut primary foam reached a predetermined height, and cooling was immediately started. Then, while maintaining the compressed state, the foam was cooled and pressed until it reached room temperature (23°C) to obtain a secondary foam. This secondary foam was used as the cross-linked foam for Examples 1 to 27 and Comparative Examples 1 to 38.

[0064] Table 1 shows the mixing ratio (parts by weight [phr]), data after primary foaming, and data after thermoforming for the cross-linked foams of Examples 1 to 9.

[0065] [Table 1]

[0066] Table 2 shows the mixing ratio (parts by weight [phr]), data after primary foaming, and data after thermoforming for the cross-linked foams of Comparative Examples 1 to 16.

[0067] [Table 2]

[0068] Table 3 shows the mixing ratio (parts by weight [phr]), data after primary foaming, and data after thermoforming for the cross-linked foams of Examples 10 to 18.

[0069] [Table 3]

[0070] Table 4 shows the mixing ratio (parts by weight [phr]), data after primary foaming, and data after thermoforming for the cross-linked foams of Comparative Examples 17 to 27.

[0071] [Table 4]

[0072] Table 5 shows the mixing ratio (parts by weight [phr]), data after primary foaming, and data after thermoforming for the cross-linked foams of Examples 19 to 27. In all of the cross-linked foams of Examples 19 to 27, the mixing ratio of thermoplastic resin 1 to thermoplastic resin 2 was set to "1:1".

[0073] [Table 5]

[0074] Table 6 shows the mixing ratio (parts by weight [phr]), data after primary foaming, and data after thermoforming for the cross-linked foams of Comparative Examples 28 to 38. In all of the cross-linked foams of Comparative Examples 28 to 38, the mixing ratio of thermoplastic resin 1 to thermoplastic resin 2 was set to "1:1".

[0075] [Table 6]

[0076] Table 7 shows the detailed constituent materials of each cross-linked foam shown in Tables 1 to 6.

[0077] [Table 7]

[0078] Regarding the thermoplastic resins 1 ("TAFMER DF-810") and 2 ("TAFMER DF-110") shown in Table 7, thermoplastic resin 1 has the characteristic of having a higher coefficient of dynamic friction than thermoplastic resin 2. This characteristic improves grip in shoes equipped with a unit sole made of cross-linked foam containing thermoplastic resin 1. On the other hand, thermoplastic resin 2 has the characteristic of having higher abrasion resistance than thermoplastic resin 1. This characteristic improves abrasion resistance in shoes equipped with a unit sole made of cross-linked foam containing thermoplastic resin 2.

[0079] Each crosslinked foam in Examples 1-9 and each crosslinked foam in Comparative Examples 1-16 contains thermoplastic resin 1 and thermoplastic resin 3 as shown in Table 7 (see Tables 1 and 2). That is, each crosslinked foam in Examples 1-9 and each crosslinked foam in Comparative Examples 1-16 does not contain thermoplastic resin 2. Hereinafter, the crosslinked foam containing thermoplastic resin 1 and thermoplastic resin 3 will be referred to as "crosslinked foam A". In shoes equipped with a unit sole made of crosslinked foam A, grip is relatively easy to obtain as described above because it contains thermoplastic resin 1.

[0080] Each of the crosslinked foams in Examples 10-18 and Comparative Examples 17-27 contains thermoplastic resin 2 and thermoplastic resin 3 as shown in Table 7 (see Tables 3 and 4). In other words, each of the crosslinked foams in Examples 10-18 and Comparative Examples 17-27 does not contain thermoplastic resin 1. Hereinafter, the crosslinked foam containing thermoplastic resin 2 and thermoplastic resin 3 will be referred to as "crosslinked foam B". Shoes equipped with a unit sole made of crosslinked foam B tend to have relatively good abrasion resistance, as described above, because they contain thermoplastic resin 2.

[0081] Each of the crosslinked foams in Examples 19-27 and Comparative Examples 28-38 contains all of the thermoplastic resins 1-3 shown in Table 7 (see Tables 5 and 6). Hereafter, the crosslinked foam containing all of the thermoplastic resins 1-3 will be referred to as "crosslinked foam C". Shoes equipped with a unit sole made of crosslinked foam C tend to have both a high coefficient of dynamic friction and good grip.

[0082] (DIN abrasion test) Next, DIN abrasion tests were performed on each of the cross-linked foams in Examples 1-27 and Comparative Examples 1-38. Details of the DIN abrasion tests are shown in Table 8.

[0083] [Table 8]

[0084] As shown in Table 8, the DIN abrasion test in this embodiment adopted Method B as described in the Japanese Industrial Standards "JIS K 6264-1" and "JIS K 6264-2". However, instead of using the standard test rubber for Method B, the standard test rubber for Method A as described in "JIS K 6264-1" and "JIS K 6264-2" was used for the test specimens.

[0085] DIN wear amount [mm²] for each cross-linked foam A in Examples 1-6 shown in Table 1. 3 ] and the amount of DIN wear in each cross-linked foam A of Comparative Examples 1-13 shown in Table 2 [mm 3 This is shown in Table 9.

[0086] [Table 9]

[0087] Note that the numbers labeled "Q" in the top row of Table 9 represent parts by weight [phr] of silicone resin. Similarly, the numbers labeled "E" in the left column of Table 9 represent parts by weight [phr] of EPDM. The same applies to Tables 10 to 14 described later.

[0088] In Table 9, the DIN wear amount of the crosslinked foam A without silicone rubber (the "484 mm" in Table 9) 3 and above, and the DIN wear amount is less than 250 mm 3 Those that meet the conditions are evaluated as "〇" (qualified), while those that do not meet the conditions are evaluated as "×" (unqualified). The evaluation results are shown in Table 10. Here, regarding the above "〇" (qualified) conditions, the upper limit value of the DIN wear amount is set to less than 250 mm 3 The reason for setting the upper limit value of the DIN wear amount to less than 250 mm is that when the DIN wear amount exceeds 25 mm 3 the wear powder tends to increase overall in the crosslinked foam, and due to the missing parts of the wear powder, breakage such as tearing (i.e., an event different from wear) is likely to occur.

[0089]

Table 10

[0090] The DIN wear amounts [mm of the crosslinked foams B of Examples 10 - 13, 17, 18 shown in Table 3 3 and the DIN wear amounts [mm of the crosslinked foams B of Comparative Examples 17 - 24 shown in Table 4 3 are shown in Table 11.

[0091]

Table 11

[0092] In Table 11, the DIN wear amount of the crosslinked foam B without silicone rubber (the "156 mm" in Table 11) 3 and above, and the DIN wear amount less than 250 mm 3 Those that meet the conditions are evaluated as "〇" (qualified), while those that do not meet the conditions are evaluated as "×" (unqualified). The evaluation results are shown in Table 12. Regarding the above "〇" (qualified) conditions, the reason for setting the upper limit value of the DIN wear amount to less than 250 mm is the same as the reason described in Table 10. 3

[0093] [Table 12]

[0094] DIN wear amount [mm] for each cross-linked foam C in Examples 19-22, 26, and 27 shown in Table 5 3 ] and the amount of DIN wear in each crosslinked foam C of Comparative Examples 28-35 shown in Table 6 [mm 3 This is shown in Table 13.

[0095] [Table 13]

[0096] Table 13 shows the DIN wear amount for cross-linked foam C without silicone rubber (237 mm in Table 13). 3 Equivalent to or better than ) and with a DIN wear amount of 250 mm 3 Those that met the condition of being less than the specified value were evaluated as "○" (pass), while those that did not meet the above condition were evaluated as "×" (fail). The evaluation results are shown in Table 14. Regarding the above condition of "○" (pass), the upper limit of DIN wear amount was set to 250 mm. 3 The reason for setting it to less than is the same as the reason stated in Table 10.

[0097] [Table 14]

[0098] (Friction test) Next, friction tests were performed on each of the crosslinked foams in Examples 1-27 and Comparative Examples 1-38. Details of the test conditions for the friction tests are shown in Table 15. The room temperature during the friction tests was 23±1℃. The humidity during the friction tests was 50%-60%.

[0099] [Table 15]

[0100] As a condition for comparing multiple measurement data in this friction test, data correction was performed on each measurement data to uniformly standardize the timing of the initial increase in the friction coefficient (measured value) immediately after the start of measurement. Then, since the fluctuation of the friction coefficient (measured value) stabilizes as the measurement time progresses, the friction coefficient (measured value) during the period of this stabilized state (the period from 2500ms to 2600ms after the start of measurement) was compared (see the measured values ​​shown in Tables 16, 19, and 22 below).

[0101] Furthermore, data from measurements that could not be taken under normal conditions due to foreign matter being present on the glass surface of the friction measuring machine were excluded from the measurement results of the friction test.

[0102] Table 16 shows the dynamic friction coefficients of each cross-linked foam A related to Examples 1-9 shown in Table 1, and the dynamic friction coefficients of each cross-linked foam A related to Comparative Examples 1-13 shown in Table 2.

[0103] [Table 16]

[0104] Note that the numbers labeled "Q" in the top row of Table 16 represent parts by weight [phr] of silicone resin. Similarly, the numbers labeled "E" in the left column of Table 16 represent parts by weight [phr] of EPDM. The same applies to Tables 17 to 24 described later.

[0105] Table 17 shows the percentage change [%) of the dynamic friction coefficient in each cross-linked foam A shown in Table 16, relative to the dynamic friction coefficient of cross-linked foam A without silicone rubber and without EPDM (corresponding to "3.14" in Table 16). In the following explanation, the above percentage will be referred to as the "improvement rate of the dynamic friction coefficient" (in %). The same applies to Tables 20 and 23 described later.

[0106] [Table 17]

[0107] In the values ​​shown in Table 17, values ​​with a percentage of 3% or more were evaluated as "○" (pass), while values ​​with a percentage of less than 3% were evaluated as "×" (fail). Furthermore, in Table 17, values ​​that were both 3% or more and 10% or more were evaluated as "◎" (pass). These evaluation results are shown in Table 18.

[0108] The basis for the aforementioned pass / fail criterion (3%) is based on the following sensory evaluation by humans. Specifically, the cross-linked foam A of the test subject was slid against a glass plate with a smooth surface under a load of 250g to 1000g. More specifically, the cross-linked foam A of the test subject was slid by the evaluator's hand while applying the above load. Then, based on the sensory evaluation of the difference in slipperiness, the cross-linked foam A of the test subject was compared with cross-linked foam A without silicone rubber and without EPDM (cross-linked foam A of Comparative Example 1 described in Table 2). In such a comparison, the percentage at which the cross-linked foam A of the test subject was perceived as less slippery than the cross-linked foam A without silicone rubber and without EPDM (i.e., the percentage of cross-linked foams at which a difference in slipperiness could be felt by touch) was "3% or more".

[0109] [Table 18]

[0110] Table 19 shows the dynamic friction coefficients of each cross-linked foam B related to Examples 10-18 shown in Table 3, and the dynamic friction coefficients of each cross-linked foam B related to Comparative Examples 17, 19-27 shown in Table 4.

[0111] [Table 19]

[0112] Table 20 shows the percentage change [%] in the dynamic friction coefficient of each cross-linked foam B shown in Table 19 compared to the dynamic friction coefficient of cross-linked foam B without silicone rubber and without EPDM (corresponding to "2.87" in Table 19) (improvement rate [%] of the dynamic friction coefficient).

[0113] [Table 20]

[0114] In the values ​​shown in Table 20, values ​​with a percentage of 3% or more were evaluated as "○" (pass), while values ​​with a percentage of less than 3% were evaluated as "×" (fail). Furthermore, in Table 20, values ​​with a percentage of 3% or more and a value of 10% or more were evaluated as "◎" (pass). These evaluation results are shown in Table 21. The evaluation results shown in Table 21 are based on a sensory evaluation of the difference in slip resistance, comparing the cross-linked foam B of the test subject with cross-linked foam B without silicone rubber and without EPDM (cross-linked foam B of Comparative Example 17 described in Table 4). The basis for the percentage (3%) used as the pass / fail criterion is as described above.

[0115] [Table 21]

[0116] Table 22 shows the dynamic friction coefficients of each cross-linked foam C related to Examples 19-27 shown in Table 5, and the dynamic friction coefficients of each cross-linked foam C related to Comparative Examples 28, 30-38 shown in Table 6.

[0117] [Table 22]

[0118] Table 23 shows the percentage change [%] (improvement rate [%]) of the dynamic friction coefficient in each cross-linked foam C shown in Table 22, relative to the dynamic friction coefficient of cross-linked foam C without silicone rubber and without EPDM (corresponding to "3.16" in Table 22).

[0119] [Table 23]

[0120] In the values ​​shown in Table 23, values ​​with a percentage of 3% or more were evaluated as "○" (pass), while values ​​with a percentage of less than 3% were evaluated as "×" (fail). Furthermore, in Table 23, values ​​with a percentage of 3% or more and a value of 10% or more were evaluated as "◎" (pass). These evaluation results are shown in Table 24. The evaluation results shown in Table 24 are based on a sensory evaluation of the difference in slip resistance, comparing the cross-linked foam C of the test subject with cross-linked foam C without silicone rubber and without EPDM (cross-linked foam C of Comparative Example 28 described in Table 6). The basis for the percentage (3%) used as the pass / fail criterion is as described above.

[0121] [Table 24]

[0122] (Relationship between the weight of EPDM and the rate of improvement in the coefficient of dynamic friction) Figure 2 is a graph plotting the percentage improvement in the coefficient of dynamic friction [%] for each cross-linked foam A shown in Table 17 against the weight (E) [phr] of EPDM. The black circles (·) in Figure 2 indicate the percentage improvement in the coefficient of dynamic friction [%] when the weight of the silicone resin shown in Table 17 is "2.5 phr".

[0123] Here, the circle symbol (○) in Figure 2 indicates the percentage improvement in the coefficient of dynamic friction when the weight of the silicone resin shown in Table 17 is "5 phr". The cross symbol (×) in Figure 2 indicates the percentage improvement in the coefficient of dynamic friction when the weight of the silicone resin shown in Table 17 is "7.5 phr". The square symbol (□) in Figure 2 indicates the percentage improvement in the coefficient of dynamic friction when the weight of the silicone resin shown in Table 17 is "10 phr".

[0124] Figure 3 is a graph plotting the percentage improvement in the coefficient of dynamic friction [%] for each cross-linked foam B shown in Table 20 against the weight (E) [phr] of EPDM. Note that the symbols in Figure 3 are the same as those explained in Figure 2, so a detailed explanation is omitted.

[0125] Figure 4 is a graph plotting the percentage improvement in the coefficient of dynamic friction [%] for each cross-linked foam C shown in Table 23 against the weight (E) [phr] of EPDM. Note that the symbols in Figure 4 are the same as those explained in Figure 2, so a detailed explanation is omitted.

[0126] Figures 2 to 4 show that, for any of the cross-linked foams A to C, the rate of improvement in the coefficient of dynamic friction tends to increase in proportion to the increase in the weight of EPDM in the range of 0 phr to 17.5 phr of EPDM.

[0127] On the other hand, Figures 2 to 4 show that for any of the cross-linked foams A to C, the rate of improvement in the coefficient of dynamic friction decreases as the amount of EPDM increases in the range of 17.5 phr to 20 phr. In other words, to increase the rate of improvement in the coefficient of dynamic friction, it is sufficient for the amount of EPDM to be less than 20 phr (it is not necessary to have more than 20 phr of EPDM).

[0128] As described above, from the perspective of increasing the rate of improvement of the coefficient of dynamic friction, based on the results shown in Tables 17, 20, 23, and Figures 2 to 4, the following equations (1) and (2) can be derived for each range of parts by weight of silicone resin (Q) and parts by weight of EPDM (E). [Mathematics 1] 0 <Q≦10···(1) [Math 2] 0 <E<20···(2)

[0129] (Relationship between the weight parts of EPDM and the weight parts of silicone resin) Figure 5 is a graph plotting the overlapping areas (mixing ratios) of the parts by weight of EPDM and silicone resin when they are marked with "○" (symbol) in Tables 10, 12, and 14, and the parts by weight of EPDM and silicone resin when they are marked with "○" or "◎" in Tables 18, 21, and 24. In other words, Figure 5 shows the DIN wear amount [mm²] that satisfies the predetermined conditions described above for cross-linked foams A to C. 3 This graph plots the weights of parts by weight of EPDM and parts by weight of silicone resin when both the improvement rate of the coefficient of dynamic friction [%] and the improvement rate of the coefficient of dynamic friction [%] are achieved.

[0130] Here, the square symbol (■) in Figure 5 indicates the blending ratio where the parts by weight of EPDM and silicone resin overlap with the parts by weight of EPDM and silicone resin when they are represented by "〇" (symbol) in Tables 10, 12, and 14, and when they are represented by "〇" or "◎" in Tables 18, 21, and 24.

[0131] According to Figure 5, DIN wear amount [mm 3 In order to optimize [ ] and increase the rate of improvement of the coefficient of dynamic friction [%], the following equations (3) and (4) are derived for the weight of the silicone resin and the weight of the EPDM, respectively. [Math 3] E+Q≧7.5···(3) [Math 4] EQ ≥ 2.5 ···(4)

[0132] (summary) According to the embodiments of this disclosure, it was found that in crosslinked foams A to C, in order to suppress DIN wear and increase the rate of improvement of the dynamic friction coefficient, the weight of the silicone resin and the weight of the EPDM should be configured to satisfy the relationship shown in the above formulas (1), (2), (3), and (4). In other words, in the embodiments of this disclosure, it was possible to identify the region in the weight of the silicone resin and the weight of the EPDM in the crosslinked foam composition constituting the unit sole of a shoe that can achieve both wear resistance and grip. As a result, it is possible to appropriately obtain a shoe unit sole that achieves both wear resistance, which is exhibited by the incorporation of silicone resin, and grip, which is exhibited by the incorporation of EPDM.

[0133] Furthermore, with respect to equations (1) and (2) above, and with reference to Figure 5, the more preferable ranges for parts by weight of silicone resin (Q) and parts by weight of EPDM (E) are given by equations (5) and (6) below. [Number 5] 2.5 ≤ Q ≤ 7.5 ···(5) [Number 6] 5 ≤ E ≤ 10 ···(6)

[0134] In cross-linked foams A to C, if the weight of the silicone resin and the weight of the EPDM are configured to satisfy the relationship shown in equations (5), (6), (3), and (4) above, the amount of DIN wear can be optimized and the rate of improvement of the dynamic friction coefficient can be further increased. [Industrial applicability]

[0135] This disclosure has industrial applications, for example, as a unit sole for shoes suitable for indoor sports and shoes equipped therewith. [Explanation of symbols]

[0136] 1: Shoes 2: Unit sole 3: Upper 4: Bottom

Claims

1. It is the unit sole of the shoe, The aforementioned unit sole is composed of a crosslinking foaming composition containing at least a thermoplastic resin including a polyolefin elastomer (POE), an ethylene vinyl acetate copolymer (EVA), a crosslinking agent, and a foaming agent. The aforementioned cross-linked foaming composition further contains a silicone resin and ethylene propylene rubber (EPDM), comprising a shoe unit sole.

2. In the shoe unit sole described in claim 1, A shoe unit sole in the crosslinking foam composition, wherein the parts by weight of the silicone resin (Q) and the parts by weight of the ethylene propylene rubber (EPDM) (E) satisfy the relationship shown in the following formulas (1) to (4). [Mathematics 1] 0 < Q ≤ 10 ... (1) [Math 2] 0<E<20...(2) [Mathematics 3] E+Q≧7.5...(3) [Math 4] EQ≧2.5...(4)

3. In a shoe having a unit sole according to claim 1 or 2, The bottom of the aforementioned unit sole is configured as a contact surface that can make contact with a floor or road surface, in the form of a shoe.

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