RUBBER COMPOSITION FOR SHOE SOLES

Abstract

A rubber composition for shoe soles comprises: a rubber component containing a modified styrene-butadiene copolymer rubber with a glass transition temperature of at least -35°C; and a filler containing silicon dioxide. The proportion of the modified styrene-butadiene copolymer rubber is at least 70% by mass of the total rubber component.

Description

STATE OF THE ART

[0001] The present disclosure relates to a rubber composition for use as shoe soles.

[0002] The outsoles of shoes, such as sports shoes, are made of a material with high hardness to improve adhesion or grip when walking and running, as well as abrasion resistance.

[0003] For example, a rubber composition containing a rubber component (A); a lignin degradation product (B) with an aldehyde yield of at least 12 mass% by an alkaline nitrobenzene oxidation process; and an antioxidant (C) has been proposed as a material for such outsoles. It has been described that the use of such a rubber composition makes it possible to provide a rubber composition for shoe soles that exhibits excellent grip regardless of road surface conditions (see, for example, WO 2022 / 064949).

[0004] The following rubber composition is also proposed which contains about 3 phr to 90 phr of a natural rubber component, about 10 phr to about 90 phr of bromobutyl rubber, about 2 phr to about 6 phr of a polyterpene resin, about 0.1 phr to about 5 phr of a sulfur curing component, about 10 phr to about 60 phr of silica, and about 1 phr to about 10 phr of a plasticizer and which has a wet friction coefficient of about 0.4 to about 0.65 and a dry friction coefficient of about 0.76 to about 0.90 to improve a DIN abrasion index. It has been described that the use of such a rubber composition makes it possible to provide a rubber composition for shoe soles with excellent traction and durability (see, for example, Japanese Patent Application Laid-Open No. 2019-166317). SUMMARY

[0005] The rubber composition described in WO 2022 / 064949 exhibits excellent dry and wet adhesion; however, its abrasion resistance was not investigated. Japanese Patent Application Publication No. 2019-166317 mentions the abrasion resistance of the rubber composition, but the DIN abrasion volume value is high, and the abrasion resistance is insufficient.

[0006] It is therefore an object of the present disclosure to provide a rubber composition for shoe soles which can provide shoe soles with excellent wet grip, dry grip and abrasion resistance.

[0007] To achieve the above object, a rubber composition for shoe soles of the present disclosure contains a rubber component containing a modified styrene-butadiene copolymer rubber having a glass transition temperature of at least -35°C and a filler containing silicon dioxide, wherein a proportion of the modified styrene-butadiene copolymer rubber based on the entire rubber component is at least 70% by mass.

[0008] According to the present disclosure, it is possible to provide a rubber composition for shoe soles that can provide shoe soles with excellent wet grip, dry grip and abrasion resistance. DETAILED DESCRIPTION

[0009] A preferred embodiment of the present disclosure is described below.

[0010] The rubber composition for shoe soles of the present disclosure contains a rubber component and a filler. <kautschukkomponente>

[0011] The rubber component of the rubber composition for shoe soles of the present disclosure contains a modified styrene-butadiene copolymer rubber (hereinafter also referred to as "modified SBR") having a glass transition temperature of at least -35°C.

[0012] The use of such a modified styrene-butadiene copolymer rubber can increase the static friction of the shoe soles made using the rubber composition for shoe soles, thereby enabling dry grip (i.e., grip on a dry smooth surface).

[0013] The use of such a modified styrene-butadiene copolymer rubber increases, under certain conditions, the loss factor tanδ in shoe soles produced using the rubber composition for shoe soles, which can also increase the hysteresis friction that occurs when an outsole (i.e., a viscoelastic body) moves over uneven surfaces wetted with water. The shoe soles can thus exhibit wet grip (grip on a wet surface).

[0014] The "glass transition temperature" refers here to the temperature at which the rubber state changes into the glass state during a temperature drop.

[0015] In the rubber composition for shoe soles of the present disclosure, the proportion of the modified styrene-butadiene copolymer rubber is at least 70 mass% based on the total rubber component (ie, 100 mass%). This is because if the proportion of the modified styrene-butadiene copolymer rubber is less than 70 mass%, the shoe soles may not have sufficient dry grip and wet grip.

[0016] Specifically, in the rubber composition for shoe soles of the present disclosure, the rubber component contains a modified styrene-butadiene copolymer rubber having a glass transition temperature of at least -35°C, and the proportion of the modified styrene-butadiene copolymer rubber is at least 70 mass% based on the entire rubber component. This makes it possible to sufficiently increase static friction and reliably improve dry grip. Since it is possible to increase hysteresis friction, it is also possible to reliably improve wet grip.

[0017] In order to further improve wet grip, the proportion of the rubber made of modified styrene-butadiene copolymer based on the total rubber component is preferably at least 70% by mass, more preferably at least 80% by mass.

[0018] In order to improve dry and wet adhesion and abrasion resistance, the proportion of bound styrene in the modified styrene-butadiene copolymer rubber is preferably in a range of 5 mass% to 45 mass%, more preferably in a range of 15 mass% to 35 mass%.

[0019] The "bound styrene content" refers here to the styrene unit contained in the molecular structure of the styrene-butadiene copolymer rubber.

[0020] In order to improve the mechanical strength, the vinyl bond content of the modified styrene-butadiene copolymer rubber is preferably in a range of 15 mass% to 65 mass%, more preferably in a range of 20 mass% to 60 mass%.

[0021] The "vinyl bond content" refers here to the 1,2-vinyl bond content of the styrene-butadiene copolymer rubber.

[0022] In order to improve mechanical strength and processability, the modified styrene-butadiene copolymer rubber preferably has a Mooney viscosity (ML 1+4 at 100 °C) from 40 to 150.

[0023] The "Mooney viscosity" refers here to the viscosity measured according to JIS K 6300-1 (2001).

[0024] Examples of the modified styrene-butadiene copolymer rubber include, for example, commercially available products such as Y031 manufactured by Asahi Kasei Corporation, SLR4502 manufactured by Synthos schkopau GmbH and SLR4602 manufactured by Synthos schkopau GmbH.

[0025] The rubber component in the rubber composition for shoe soles of the present disclosure may contain a rubber other than the previously described modified styrene-butadiene copolymer rubber. Examples of the different rubber include, for example, a synthetic rubber such as a butadiene rubber and an isoprene rubber, and a natural rubber. Among these rubbers, one type may be used alone, or two or more types may be used in combination.

[0026] In the case of using a different rubber described above in the rubber composition for shoe soles of the present disclosure, the proportion of the different rubber is preferably at most 30 mass% based on the entire rubber component (i.e., 100 mass%). This is because when the proportion of the different rubber is more than 30 mass%, the ratio of the modified styrene-butadiene copolymer rubber in the entire rubber component is reduced, which lowers the glass transition temperature of the entire rubber component. Due to this decrease in the glass transition temperature, the hysteresis friction does not increase sufficiently, which may result in insufficient wet grip.

[0027] In order to further improve wet grip, the proportion of the different rubber based on the total rubber component is preferably at most 30 mass%, more preferably at most 20 mass%.

[0028] The synthetic rubber and natural rubber described above are not specifically limited, and any commercially available synthetic rubber and natural rubber can be used. <Füllstoff>

[0029] The rubber composition for shoe soles of the present disclosure contains a filler to improve dry and wet grip and abrasion resistance.

[0030] Examples of fillers include silica, carbon black, magnesium carbonate, calcium carbonate, clay, talc, and barium sulfate. Among these fillers, one type can be used alone, or two or more types can be used in combination.

[0031] In addition, in the rubber composition for shoe soles of the present disclosure, a filler containing silica is used to improve wet grip and abrasion resistance.

[0032] Examples of the silica include anhydrous silica and hydrated silica. The BET specific surface area of silica (measured according to ISO 5794 / 1) is preferably at least 50 m 2 / g, more preferably at least 100 m 2 / g and even more preferably at least 150 m 2 / g and is preferably not more than 350 m 2 / g, more preferably not more than 300 m 2 / g and even more preferably a maximum of 250 m 2 / g to improve the dispersibility of the silica in the rubber composition and the resulting rubber body, as well as the rubber-reinforcing properties. Among these silicas, one type can be used alone, or two or more types can be used in combination.

[0033] The silica content is preferably at least 40 parts by mass and at most 70 parts by mass per 100 parts by mass of the rubber component. This is because at a silica content of less than 40 parts by mass, abrasion resistance may not increase sufficiently in some cases; at a silica content of more than 70 parts by mass, processability may decrease, and adhesion may decrease due to an increase in hardness.

[0034] Examples of silica include commercially available products such as Nipsil VN3 manufactured by Tosoh Silica Corporation. <silan-haftvermittler>

[0035] The rubber composition for shoe soles of the present disclosure may contain a silane coupling agent to improve the dispersibility of the filler in the rubber composition for shoe soles.

[0036] Examples of silane coupling agents include, for example, sulfide-based coupling agents such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, bis(4-trimethoxysilylbutyl)trisulfide, bis(3-triethoxysilylpropyl)disulfide, bis(2-triethoxysilylethyl)disulfide, bis(4-triethoxysilylbutyl)disulfide, bis(3-trimethoxysilylpropyl)disulfide, bis(2-trimethoxysilylethyl)disulfide, bis(4-trimethoxysilylbutyl)disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide, 2-Triethoxysilylethyl-N,N-dimethylthiocarbamoyl tetrasulfide and 3-triethoxysilylpropyl methacrylate monosulfide; and mercapto-based coupling agents such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, and NXT and NXT-Z manufactured by Momentive Performance Materials Japan LLC.Of these silane coupling agents, one type can be used alone or two or more types can be used in combination.

[0037] Examples of mercapto-based silane coupling agents include NXT-Z45 (condensation product of 3-octanoylthio-1-propyltriethoxysilane) manufactured by Momentive Performance Materials Japan LLC. Examples of sulfide-based silane coupling agents include commercially available products such as Si-69 (bis[3-(triethoxysilyl)propyl]tetrasulfide) manufactured by Evonik Japan Co., Ltd.

[0038] The proportion of the silane coupling agent is preferably at least 5 parts by mass and at most 10 parts by mass per 100 parts by mass of silica. This is because when the proportion of the silane coupling agent is less than 5 parts by mass, the dispersibility of the silica may be insufficient in some cases; when the proportion of the silane coupling agent is more than 10 parts by mass, the coupling effect and silica dispersion may be insufficient, resulting in a deterioration in the reinforcing properties and a lower strength of the rubber composition for shoe soles. <Oil>

[0039] The rubber composition for shoe soles of the present disclosure may contain oil to improve wet grip. Examples of the oil include, for example, mineral oils such as paraffinic oils, naphthenic oils, and aromatic oils; vegetable oils such as castor oil, linseed oil, tall oil fatty acid, and pine tar; ester compounds such as fatty acid esters, phthalic acid esters, and phosphoric acid esters; and chemically synthesized oils such as poly-α-olefins. Among these oils, one type may be used alone, or two or more types may be used in combination.

[0040] The oil content is preferably at least 10 parts by mass and at most 30 parts by mass per 100 parts by mass of the rubber component. This is because with an oil content of less than 10 parts by mass, the softening effect of the additive may not be achieved in some cases; with a content of more than 30 parts by mass, the abrasion resistance may decrease. <vulkanisationsmittel>

[0041] The rubber composition for shoe soles of the present disclosure may contain sulfur as a vulcanizing agent.

[0042] Examples of sulfur include powdered sulfur, precipitated sulfur, insoluble sulfur, colloidal sulfur, and surface-treated sulfur. Of these sulfurs, one type can be used alone, or two or more types can be used in combination.

[0043] The proportion of the vulcanizing agent is preferably at least 0.5 parts by mass and at most 5.0 parts by mass per 100 parts by mass of the rubber component. This is because a vulcanizing agent content of less than 0.5 parts by mass may result in insufficient hardness and mechanical strength of the outsoles; a content of more than 5.0 parts by mass may result in excessive hardness of the outsoles. <vulkanisationsbeschleuniger>

[0044] The rubber composition for shoe soles of the present disclosure may contain a vulcanization accelerator. The vulcanization accelerator is not particularly limited, and examples of the vulcanization accelerator include, for example, sulfenamide-based, guanidine-based, thiazole-based, thiuram-based, thiourea-based, dithiocarbamic acid-based, aldehyde amine-based, aldehyde ammonia-based, imidazoline-based, and xanthate-based vulcanization accelerators. Among them, one type may be used alone, or two or more types may be used in combination.

[0045] The proportion of the vulcanization accelerator is preferably at least 0.1 part by mass and at most 2.5 parts by mass per 100 parts by mass of the rubber component. This is because if the proportion of the vulcanization accelerator is less than 0.1 part by mass, vulcanization may be insufficient in some cases; if the proportion exceeds 2.5 parts by mass, excessive vulcanization may occur. <verarbeitungshilfsstoff>

[0046] The rubber composition for shoe soles of the present disclosure may contain a processing aid to improve the flowability and lubricity of the rubber composition for shoe soles, reduce adhesion to a mixing machine such as a roller or the like, and increase the mold release effect.

[0047] Examples of the processing aid include higher fatty acid esters, stearic acid, metallic soaps and polyethylene wax.

[0048] The proportion of the processing aid is preferably 5.0 parts by mass or less per 100 parts by mass of the rubber component. This is because if the proportion of the processing aid exceeds 5.0 parts by mass, the lubricity becomes excessive, resulting in slippage between the roller and the material, thus causing difficulties in mixing the materials in the rolling process. <Weitere Bestandteile>

[0049] The rubber composition for shoe soles of the present disclosure may contain other components within a range that does not impair the effects of the present disclosure. As other components, known additives generally used in the rubber composition for shoe soles can be used, and examples thereof include, for example, vulcanization accelerator aids such as zinc oxide, vulcanization activators such as polyethylene glycol, antioxidants such as styrenated phenol, and color masterbatches such as black masterbatch. Of these additives, one type may be used alone, or two or more types may be used in combination.

[0050] In the shoe soles produced using the rubber composition for shoe soles of the present disclosure, a loss factor tanδ at -10 °C and a frequency of 10 Hz is at least 0.3 to improve hysteresis friction and achieve excellent wet grip.

[0051] The loss factor tanδ of the shoe soles can be determined by analyzing data measured by dynamic viscoelasticity measurement for the shoe soles using data processing software.

[0052] Specifically, the value of tanδ at -10 °C and 10 Hz is extracted using data processing software based on the data obtained at a predetermined measurement temperature and measurement frequency for the shoe sole. For example, "Rheogel E4000F" manufactured by UBM can be used for dynamic viscoelasticity measurement, and "UBM Rheo Station ver. 7.0" manufactured by UBM is used as data processing software.

[0053] In the shoe soles produced using the rubber composition for shoe soles of the present disclosure, a dynamic friction coefficient µ Kdry in a dry friction test described later, preferably at least 1.15 to improve static friction and dry adhesion. It can be said that the larger the value of the dynamic friction coefficient µ Kdry is, the greater the frictional force and the less likely the shoe soles are to slip, which means that dry grip increases.

[0054] In the shoe soles produced using the rubber composition for shoe soles of the present disclosure, a dynamic friction coefficient µ Koil in a friction test described later in an oil-lubricated condition, preferably at least 0.38 to increase hysteresis friction and wet grip. This value is considered to be the friction derived from hysteresis friction excluding static friction. It can be said that the larger the value of the dynamic friction coefficient µ Koil is, the greater the frictional force due to hysteresis and the less likely the shoe soles are to slip, which means that wet grip increases.

[0055] In the shoe soles produced using the rubber composition for shoe soles of the present disclosure, the difference between the dynamic friction coefficient µ Kdry and the dynamic friction coefficient µ Koil (ie µ Kdry - µ Koil ) is considered to be the coefficient of static friction. As previously described, µ Koil the friction derived from the hysteresis friction, so that the difference to µ Kdry is the static friction force. If this value is at least 0.7, the static friction increases and excellent dry adhesion can be achieved.

[0056] The "dynamic friction coefficient" can be determined in the present case by the method described in examples which will be described later.

[0057] In the shoe soles produced using the rubber composition for shoe soles of the present disclosure, a DIN abrasion volume is preferably at most 160 mm 3 to increase abrasion resistance. It can be said that the smaller the value of the DIN abrasion volume, the greater the durability, which means that the abrasion resistance increases.

[0058] The "DIN abrasion volume" can be determined in the present case by the method described in examples which will be described later.

[0059] In the shoe soles produced using the rubber composition for shoe soles of the present disclosure, the tensile strength is preferably at least 12 MPa in order to increase the strength.

[0060] The "tensile strength" here refers to the tensile strength measured according to JIS K 6251 (2018). <Verfahren zur Herstellung der Kautschukzusammensetzung für Schuhsohlen>

[0061] The following describes a method for producing the rubber composition for shoe soles of the present disclosure. In producing the rubber composition for shoe soles of the present disclosure, raw materials such as the above-described rubber component, the above-described filler, the above-described silane coupling agent, the above-described oil, the above-described vulcanizing agent, the above-described vulcanization accelerator, and the above-described processing aid are first added to a mixer and kneaded to produce the rubber composition for shoe soles.

[0062] Examples of the mixing machine here include, for example, a mixing roller, a calender roller, a Banbury mixer and a kneader.

[0063] For example, kneading can be carried out stepwise using a variety of mixing machines: For example, a rubber component, a filler, a silane coupling agent, and a processing aid are added to a kneader and kneaded, and the kneaded composition is then transferred to a roll into which a vulcanizing agent and a vulcanization accelerator are added for kneading.

[0064] All materials can be placed in a set of rollers set to a predetermined temperature and kneaded.

[0065] In this way, the rubber composition for shoe soles of the present disclosure can be prepared. EXAMPLES

[0066] The present disclosure will be described below using examples. The present disclosure is not limited to these examples, and various modifications and variations can be made to these examples without departing from the scope and spirit of the present disclosure.

[0067] The materials used to manufacture the rubber composition for shoe soles are listed below. (1) Modified SBR1 (glass transition temperature: -30 °C, bound styrene content: 26 mass%, 1,2-vinyl bond content: 49 mass%, Mooney viscosity (ML 1+4 at 100 °C): 65, manufactured by Asahi Kasei Corporation, trade name: Y031) (2) Modified SBR2 (glass transition temperature: -25 °C, bound styrene content: 21 mass%, 1,2-vinyl bond content: 49 mass%, Mooney viscosity (ML 1+4 at 100 °C): 65, manufactured by Synthos schkopau GmbH, trade name: SLR4602) (3) Modified SBR3 (glass transition temperature: -35 °C, bound styrene content: 20 mass%, 1,2-vinyl bond content: 42 mass%, Mooney viscosity (ML 1+4 at 100 °C): 60, manufactured by Synthos schkopau GmbH, trade name: SLR4502) (4) Modified SBR4 (glass transition temperature: -62 °C, bound styrene content: 15 mass%, 1,2-vinyl bond content: 42 mass%, Mooney viscosity (ML 1+4 at 100 °C): 60, manufactured by Synthos schkopau GmbH, trade name: SLR3402) (5) Unmodified SBR (bound styrene content: 46, 1,2-vinyl bond content: 16, Mooney viscosity (ML 1+4 at 100 °C): 45, manufactured by ENEOS Materials Corporation, trade name: ESBR0202) (6) Butadiene rubber (manufactured by UBE Corporation, trade name: UBEPOL150L) (7) Natural rubber (trade name: SVR-CV60) (8) Silicon dioxide (Manufactured by Tosoh Silica Corporation, trade name: Nipsil VN3) (9) Oil (manufactured by Idemitsu Kosan Co., Ltd., trade name: PW32) (10) Silane coupling agent 1 (condensation product of 3-octanoylthio-1-propyltriethoxysilane, manufactured by Momentive Performance Materials Japan LLC., trade name: NXT Z45) (11) Silane coupling agent 2 (bis[3-(triethoxysilyl)propyl]tetrasulfide, manufactured by Evonik Japan Co., Ltd., trade name: Si-69) (12) Vulcanization accelerator (active zinc oxide, manufactured by SEIDO CHEMICAL INDUSTRY CO., LTD., trade name: active zinc oxide AZO) (13) Processing aid (stearic acid, manufactured by NOF CORPORATION, trade name: Stearic Acid Camellia) (14) Vulcanization activator (polyethylene glycol, manufactured by Junsei Chemical Co., Ltd., trade name: PEG#4000) (15) Antioxidant 1 (styrenated phenols, manufactured by OUCHI SHINKO CHEMICAL INDUSTRIAL CO., LTD., trade name: SP-N) (16) Antioxidant 2 (2-mercaptobenzimidazole, manufactured by OUCHI SHINKO CHEMICAL INDUSTRIAL CO., LTD., trade name: MB) (17) Vulcanizing agent (sulfur, manufactured by HOSOI CHEMICAL INDUSTRY CO., LTD., trade name: Sulfur#200) (18) Vulcanization accelerator 1 (N-oxydiethylenebenzothiazole-2-sulfenamide, manufactured by OUCHI SHINKO CHEMICAL INDUSTRIAL CO., LTD., trade name: MSA) (19) Vulcanization accelerator 2 (tetramethylthiuram monosulfide, manufactured by OUCHI SHINKO CHEMICAL INDUSTRIAL CO., LTD., trade name: TS) (20) Vulcanization accelerator 3 (Diphenylguanidine, manufactured by OUCHI SHINKO CHEMICAL INDUSTRIAL CO., LTD., trade name: D(DP)) (21) Color masterbatch (natural rubber black color masterbatch, manufactured by Shinko Co., Ltd.) (Examples 1 to 14 and Comparative Examples 1 to 7)<Vorbereitung der Kautschukzusammensetzung>

[0068] According to the following production process, rubber compositions for shoe soles according to Examples 1 to 14 and Comparative Examples 1 to 7 were prepared, which are shown in Tables 1 to 3, in which the numbers represent the parts by mass for the respective components.

[0069] First, the rubber component, silica, oil, silane coupling agent, and various additives (vulcanization accelerator, processing aid, vulcanization activator, and antioxidants) listed in Table 1 were mixed together and added to a kneader set at 130°C. The raw materials were kneaded for 10 minutes. Subsequently, the kneaded composition was fed into a 10-inch open roll (at a temperature of 60°C), and then the vulcanizing agent, vulcanization accelerators, and color masterbatch shown in Table 1 were added. The raw materials were further kneaded to prepare the rubber composition.

[0070] Subsequently, this rubber composition was pressed for about 5 minutes using a press machine under conditions of a temperature of 160°C and a pressure of about 20 MPa to prepare a rubber sheet 1 with a length of 200 mm, a width of 130 mm, and a thickness of 2 mm. Similarly, a rubber sheet 2 with a length of 100 mm, a width of 100 mm, and a thickness of 6 mm was prepared. <Bewertung der Nasshaftung>

[0071] The rubber composition prepared as described above was subjected to dynamic viscoelasticity measurement using a dynamic viscoelasticity meter (Rheogel-E4000F, manufactured by UBM) under the following measurement conditions. Specifically, first, the rubber sheets 1 obtained in Examples 1 to 14 and Comparative Examples 1 to 7 were cut into strips with a length of 20 mm, a width of 6 mm, and a thickness of 2 mm to obtain test specimens. Then, each test specimen was fixed at both ends to fixing points of the dynamic viscoelasticity meter, a load was applied to prevent loosening, and kept under tension. In this state, dynamic stress was applied to the test piece by driving the vibrator of the dynamic viscoelasticity meter to cause dynamic distortion.The dynamic stress and dynamic strain were recorded by the respective detectors, and the phase difference and dynamic complex elastic modulus were determined from the respective waveforms. The storage elastic modulus E' and the loss elastic modulus E'' were determined. The measurement conditions for the dynamic viscoelasticity measurement with the dynamic viscoelasticity meter were as follows. (Measurement conditions) - Measurement mode: Temperature dependence of frequency - Distorted waveform: sine wave - Measuring frequency settings: 100 Hz, 50 Hz, 30 Hz, 10 Hz, 6 Hz, 3 Hz - Distortion control: 50 µm (automatic control) - Static load control: automatic static load - Measuring temperature: -20 °C to 50 °C - Step temperature: 2 °C - Temperature rise rate: 2 °C / min - Hold time: 0 s. - Offset temperature: -30 °C

[0072] Subsequently, data on tanδ (-10 °C) at -10 °C and 10 Hz were extracted from the data obtained with the dynamic viscoelasticity meter. Wet adhesion was evaluated using the following criteria. The results are presented in Tables 1 to 3. tanδ (at -10 °C) is at least 0.3 ... good tanδ (at -10 °C) is less than 0.3 ... poor <Bewertung der Trockenhaftung>

[0073] The dynamic friction coefficient on the surface of the rubber compositions prepared in Examples 1 to 14 and Comparative Examples 1 to 7 was measured according to the following test method.

[0074] Specifically, the rubber sheet (each of the rubber sheets 1 obtained in Examples 1 to 14 and Comparative Examples 1 to 7) having a thickness of 2 mm and mounted on a sliding table was subjected to a 10 mm wide line contact device under a 250 g weight at 23 °C ± 3 °C under atmospheric pressure using a friction tester (manufactured by Trinity-Lab. Inc., trade name: TL201Tt). Thereafter, the rubber sheet was displaced at a sliding speed of 10 mm / s over a distance of 20 mm; the dynamic friction coefficient between 7 mm and 13 mm was measured and expressed as the dynamic friction coefficient µ. Kdry defined in the dry state.

[0075] The measurement was carried out three times, and the mean value of the dynamic friction coefficients µ Kdry of the three measurements was calculated and used as the dynamic friction coefficient at the surface of the rubber composition.

[0076] Furthermore, the dynamic friction coefficient µ Koil in an oil condition by a measuring method similar to the previously described measuring method for the dynamic friction coefficient µ Kdry in the dry state, wherein the surfaces of the above-described rubber sheets having a thickness of 2 mm (the rubber sheets 1 obtained in Examples 1 to 14 and Comparative Examples 1 to 7) were sufficiently wetted with silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., having a viscosity of 100 cSt).

[0077] The difference between the measured dynamic friction coefficient µ Kdry and the measured dynamic friction coefficient µ Koil (ie µ Kdry - µ Koil ) was calculated. Dry adhesion was evaluated using the following criteria. The results are shown in Tables 1 to 3. µ Kdry - µ Koil is at least 0.7 ... good µ Kdry - µ Koil is less than 0.7 ... bad <Bewertung der Abriebfestigkeit>

[0078] The rubber compositions prepared in Examples 1 to 14 and Comparative Examples 1 to 7 were subjected to a DIN abrasion test according to JIS K 6264-2: 2005 using a DIN abrasion tester (manufactured by Gotech Testing Machines Inc., trade name: GT-7012-D).

[0079] A circular test specimen with a diameter of 16 mm was punched out from each of the prepared 6 mm thick rubber sheets (ie the rubber sheets 2 obtained in Examples 1 to 14 and Comparative Examples 1 to 7) and used as a test specimen for the DIN abrasion test.

[0080] The test specimen was placed in a tester and abraded by sliding it over a total distance of 40 m while rotating it with a compressive load of 10 N. The test specimen was moved on a drum wrapped with a 60-grit abrasive cloth (the drum diameter was 150 mm and the rotation speed was 40 rpm). The DIN abrasion volume [mm] was then determined based on the mass of the test piece removed due to abrasion. 3 ] calculated.

[0081] The abrasion resistance was then evaluated based on the following criteria. The results are presented in Tables 1 to 3.

[0082] The DIN abrasion volume is a maximum of 160 mm 3 ... good

[0083] The DIN abrasion volume is more than 160 mm 3 ... bad <Bewertung der Festigkeit>

[0084] The tensile strength [MPa] of the rubber compositions prepared in Examples 1 to 14 and Comparative Examples 1 to 7 was measured according to JIS K 6251 (2018). Specifically, a dumbbell-shaped specimen was prepared according to Dumbbell Specimen No. 3, and a tensile test was conducted under the conditions of a temperature of 23 °C and a tensile speed of 500 mm / min using a tensile tester (manufactured by Instron, trade name: Instron 3365), and the tensile strength [MPa] at the time of specimen fracture was measured.

[0085] The strength was evaluated using the following criteria. The results are shown in Tables 1 to 3.

[0086] The tensile strength is at least 12 MPa ... good

[0087] The tensile strength is less than 12 MPa ... poor [Table 1] Examples 1 2 3 4 5 6 7 8 Milk ratio (parts by mass) Modified SBR 1 100,0 90,0 70,0 Modified SBR 2 100,0 90,0 70,0 Modified SBR 3 100,0 90,0 Modified SBR 4 Unmodified SBR Butadiene rubber 10,0 30.0 10,0 30,0 10,0 Natural rubber Silicon dioxide 40,0 40,0 40,0 40,0 40,0 40,0 40,0 40,0 Öl 10,0 10,0 10,0 10,0 10,0 10,0 10,0 10,0 Silane adhesion promoter 1 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 Silana Detention Investigator 2 Vulcanization accelerator aid 1,0 1,0 1,0 1.0 1,0 1.0 1,0 1,0 processing aid 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Vulcanization activator 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Antioxidant 1 2,0 2,0 2,0 2,0 2,0 2,0 2,0 2,0 Antioxidant 2 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Vulcanizing agent 1,0 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Vulcanization accelerator 1 1.5 1.5 1.5 1.5 1,5 1,5 1.5 1.5 Vulcanization accelerator 2 0,7 0,7 0,7 0,7 0,7 0,7 0,7 0,7 Vulcanization accelerator 3 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 Color masterbatch 0,5 0,5 0,5 0,5 0,5 0,5 0,5 0,5 sum 162,20 162,20 162,20 162,20 162,20 162,20 162,20 162,20 Evaluation tanδ (-10 °C) [-] 1,19 1,16 0,61 0,83 0,31 0,73 0,30 0,39 µ Kdry [-] 1,49 1,28 1,74 1.87 1.38 1.80 1.15 1.42 µ Koil [-] 0,55 0,48 0,45 0,51 0,45 0,53 0,40 0,38 µ Kdry - µ Koil [-] 0,94 0,80 1,29 1,36 0,93 1,27 0,75 1.04 DIN abrasion volume [mm 3 ] 145 159 130 115 93 111 87 123 Tensile strength [MPa] 16 15 14 17 14 16 16 16 [Table 2] Examples 9 10 11 12 13 14 Mixing ratio (parts by mass) Modified SBR 1 Modified SBR 2 100,0 100,0 100,0 100,0 100,0 70,0 Modified SBR 3 Modified SBR 4 Unmodified SBR Butadiene rubber Natural rubber 30,0 Silicon dioxide 40,0 40,0 40,0 70,0 70,0 40,0 Öl 10,0 10,0 10,0 10,0 30,0 10,0 Silane adhesion promoter 1 4,0 4,4 3,5 3,5 2,0 Silane Adhesion Investigator 2 2,0 Yulkanization accelerator aid 1.0 1,0 1,0 1.0 1,0 1,0 processing aid 1,0 1,0 1,0 1,0 1,0 1,0 Vulcanization accelerator 1,0 1,0 1,0 1,0 1,0 1,0 Antioxidant 1 2,0 2,0 2,0 2,0 2,0 2,0 Antioxidant 2 1,0 1,0 1,0 1,0 1,0 1,0 Vulcanizing agent 1,0 1,0 1,0 1,0 1,0 1,0 Vulcanization accelerator 1 1,5 1,5 1,5 1,5 1,5 1,5 Vulcanization accelerator 2 0,7 0,7 0,7 0,7 0,7 0,7 Vulcanization accelerator 3 0,5 0,5 0,5 0,5 0,5 0,5 Color masterbatch 0,5 0,5 0,5 0,5 0,5 0,5 sum 162,20 164,20 164,60 193,70 213,70 162,20 Evaluation taαδ (-10° C) [-] 1,04 1,18 1,21 0,53 0,35 0,69 µ Kdry [-] 1,54 1.86 1.95 1,38 1,4 1,81 µ Koil [-] 0,52 0,45 0,46 0,44 0,41 0,50 µ Kdry - µ Koil [-] 1,02 1,41 1,49 0,94 1,13 1,31 DIN abrasion volume [mm 3 ] 152 148 157 146 141 152 Tensile strength [MPa] 16 14 1 22 20 20 [Table 3] Comparison examples 1 2 3 4 5 6 7 Mixing ratio (parts by mass) Modified SBR 1 Modified SBR 2 60,0 Modified SBR 3 Modified SBR 4 100,0 Unmodified SBR 100,0 75,0 50,0 25,0 Butadiene rubber 40,0 25,0 50,0 75,0 100,0 natural rubber Silicon dioxide 40,0 40,0 40,0 40,0 40,0 40,0 40,0 Öl 10,0 10,0 10,0 10,0 10,0 10,0 10,0 Silane coupling agent 1 2,0 2,0 2,0 2,0 2,0 1,0 2,0 Silane coupling agent 2 Vulcanization accelerator aid 1,0 1,0 1,0 1,0 1,0 1,0 1,0 processing aid 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Vulcanization activator 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Antioxidant 1 2,0 2,0 2,0 2,0 2,0 2,0 2,0 Antioxidant 2 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Vulcanizing agent 1,0 1,0 1,0 1,0 1,0 1,0 1,0 Vulcanization accelerator 1 1,5 1,5 1,5 1,5 1,5 1,5 1,5 Vulcanization accelerator 2 0,7 0,7 0,7 0,7 0,7 0,7 0,7 Vulcanization accelerator 3 0,5 0,5 0,5 0,5 0,5 0,5 0,5 Color masterbatch 0,5 0,5 0,5 0,5 0,5 0,5 0,5 sum 162,20 162,20 162,20 162,20 162,20 162,20 162,20 Evaluation tanδ (-10 °C) [-] 0,12 0,17 0,92 0,83 0,61 0,34 0,10 µ Kdry [-] 1,78 1,06 1,52 0,96 0,78 0,08 0,77 µ Koil [-] 0,48 0,37 0,59 0,35 0,30 0,24 0,20 µ Kdry - µ Koil [-] 1,30 0,69 0,93 0,61 0,48 0,44 0,57 DIN abrasion volume [mm 3 ] 87 79 216 69 45 33 31 Tensile strength [MPa] 15 14 28 29 24 20 18

[0088] As shown in Table 1, in each of Examples 1 to 14, which use the rubber composition for shoe soles containing silica and a rubber component containing a modified styrene-butadiene copolymer rubber having a glass transition temperature of at least -35 °C, the proportion of the modified styrene-butadiene copolymer rubber based on the total rubber component being at least 70 mass %, the wet grip is excellent because tan δ (-10 °C) is at least 0.3. It was also found that the examples have excellent dry grip because µ Kdry - µ Koil 10 is at least 0.7. It has also been shown that the examples have excellent abrasion resistance, since the DIN abrasion volume is at most 160 mm 3 It was further found that the examples exhibit excellent strength, as the tensile strength is at least 12 MPa. INDUSTRIAL SUITABILITY

[0089] As previously described, the present disclosure is particularly useful as a rubber composition for use as shoe soles. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2022 / 064949 [0003, 0005] JP 2019-166317

[0004] Cited non-patent literature

[0000] JIS K 6300-1 (2001

[0023] JIS K 6264-2: 2005

[0078] < / verarbeitungshilfsstoff> < / vulkanisationsbeschleuniger> < / vulkanisationsmittel> < / kautschukkomponente>

Claims

[1] A rubber composition for shoe soles, the rubber composition comprising: a rubber component containing a modified styrene-butadiene copolymer rubber having a glass transition temperature of at least -35 °C; and a filler containing silicon dioxide, wherein the proportion of the rubber made of modified styrene-butadiene copolymer based on the total rubber component is at least 70% by mass. [2] A rubber composition according to claim 1, comprising: a silane coupling agent, whereby a proportion of the silane coupling agent based on 100 parts by mass of the silicon dioxide is at least 5 parts by mass and at most 10 parts by mass. [3] The rubber composition according to claim 1 or 2, wherein a proportion of the silica is at least 40 parts by mass and at most 70 parts by mass based on 100 parts by mass of the rubber component. [4] The rubber composition according to any one of claims 1 to 3, wherein the rubber component contains a rubber different from the modified styrene-butadiene copolymer rubber, and a proportion of the different rubber based on the entire rubber component is at most 30 mass%.