Soles and footwear equipped with them

Abstract

To provide a shoe sole that comprises cellulose fiber and has improved wear resistance and also provide footwear having the shoe sole.SOLUTION: A shoe sole has vulcanized non-foamed rubber, filler, cellulose fiber, and mercapto-based silane coupling agent. When measured by the Williams wear test B method of JIS K 6264-2, an amount of wear of it is 470 mm3 / 1000 rotations or less. There is also provided footwear having the shoe sole.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a shoe sole and footwear provided with the same.

Background Art

[0002] A shoe sole is provided on the surface of the footwear that contacts the ground. Since the shoe sole contacts the ground, it affects the anti-slip performance of the shoe and the ease of fatigue when wearing the footwear. As shown in Patent Document 1 below, shoe soles with improved functionality have also been proposed.

[0003] Patent Document 1 describes a footwear sole composed of a rubber composition in which cellulose fibers having a specific average fiber diameter and a specific average fiber length are blended with rubber so that the blending amount of the cellulose fibers becomes a specific blending amount. This footwear sole is said to exhibit high anti-slip performance on a floor surface to which water or oil adheres.

[0004] Patent Document 2 describes that a rubber composition containing styrene-butadiene rubber, butadiene rubber, silica, a silane coupling agent, and a crosslinking agent and containing styrene-butadiene rubber and butadiene rubber in a predetermined ratio constitutes a member for shoe molding. Patent Document 2 describes that when a mercapto-based silane coupling agent is blended, the wear resistance of the rubber is improved while the hardness increases.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The inventors of this invention have found that, as described in Patent Document 1, while shoe soles constructed by compounding cellulose fibers with rubber offer improved slip resistance, the abrasion resistance of the shoe sole may be insufficient, raising concerns that the sole may wear down easily due to friction.

[0007] Furthermore, the inventors found that in shoe soles constructed by compounding cellulose fibers with rubber, simply compounding a mercapto-silane coupling agent sometimes resulted in insufficient abrasion resistance, and the soles tended to wear down easily due to friction.

[0008] The present invention aims to provide a shoe sole with improved abrasion resistance, incorporating cellulose fibers. It also aims to provide footwear equipped with this shoe sole. [Means for solving the problem]

[0009] A shoe sole containing vulcanized non-foamed rubber, a filler, cellulose fibers, and a mercapto-silane coupling agent, with an abrasion resistance of 470 mm as determined by the Williams abrasion test method B of JIS K 6264-2. 3 The above problem is solved by using a shoe sole with a rotation speed of 1000 revolutions per minute or less. Furthermore, the above problem is solved by footwear equipped with such a shoe sole.

[0010] In the above-mentioned soles and footwear, the cellulose fibers preferably have an average fiber length of 1900 μm or less. Furthermore, in the above-mentioned soles and footwear, the hardness of the soles is preferably 55 to 72. Furthermore, in the above-mentioned soles and footwear, the filler preferably contains a hollow-structured filler. Furthermore, in the above-mentioned soles and footwear, the specific gravity of the soles is preferably 1.3 or less. [Effects of the Invention]

[0011] According to the present invention, it is possible to improve the abrasion resistance of a shoe sole containing cellulose fibers, and to provide footwear equipped with such an abrasion-resistant shoe sole. [Modes for carrying out the invention]

[0012] Preferred embodiments of the present invention will be described below. However, the technical scope of the present invention is merely illustrative and not limited to the following embodiments.

[0013] The present invention relates to a shoe sole containing vulcanized non-foamed rubber, a filler, cellulose fibers, and a mercapto-silane coupling agent, and footwear equipped with the shoe sole. The shoe sole has an abrasion amount of 470 mm as determined by the Williams abrasion test method B of JIS K 6264-2. 3 It is less than 1000 revolutions per minute.

[0014] The rubber used can be any type commonly used for shoe soles, such as one or more rubbers selected from the group consisting of natural rubber, styrene-butadiene rubber, butadiene rubber, urethane rubber, nitrile rubber, ethylene-propylene-diene rubber, and thermoplastic elastomers.

[0015] Examples of the thermoplastic elastomers mentioned above include styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, ester-based thermoplastic elastomers, and amide-based thermoplastic elastomers. These thermoplastic elastomers may be used individually or as a mixture of two or more.

[0016] The above-mentioned filler can be a powder or granule made of an inorganic substance. For example, a solid filler selected from the group consisting of silica, talc, calcium carbonate, carbon, clay, and alumina can be used. Alternatively, one or more hollow-structured fillers selected from the group consisting of glass balloons and fly ash balloons can be used as the above-mentioned filler. Using a solid filler, for example, a shoe sole with a specific gravity of 1.3 or less can be manufactured. Using a hollow-structured filler, a lightweight shoe sole can be obtained. For example, a shoe sole with a specific gravity of 1.1 or less can be obtained. The lower limit of the specific gravity is not particularly limited, but for example, it is 0.8 or higher. When silica is used as the filler, dry silica such as fumed silica or wet silica such as colloidal silica may be used. The particle size of the filler is not particularly limited, but for example, a BET specific surface area of ​​50-600 m² is possible. 2 / g, more comfortably 50-350m 2 You can use products that are / g.

[0017] As the cellulose fiber, any fiber with an arbitrary average fiber width can be used. For example, a fiber with an average fiber width of 500 μm or less may be used, a fiber with an average fiber width of 50 μm or less may be used, a fiber with an average fiber width of 30 μm or less may be used, or a fiber with an average fiber width of less than 1000 nm may be used. Using a cellulose fiber with an average fiber length of less than 1000 nm is preferable because it can improve strength while suppressing an increase in the hardness of the sole. The average fiber length of the cellulose fiber is not particularly limited, but for example, one with a length of 5 nm or more can be used.

[0018] The average fiber width or average fiber length of cellulose fibers is determined as follows. Prepare a suspension containing cellulose fibers, place the suspension on a carbon-coated grid that has been hydrophilized, and observe it with a transmission electron microscope. At this time, it may also be observed with a scanning electron microscope. Observe at any magnification of 1000 times, 5000 times, 10,000 times, 20,000 times, 50,000 times, or 100,000 times according to the width of the cellulose fibers contained in the sample to be observed. However, the preparation and observation of the sample shall satisfy the following two conditions. 1. When a straight line is drawn in the observed image, make sure that the straight line intersects with 20 or more fibers. 2. Draw a second straight line that intersects the straight line drawn in the above image, and make sure that the second straight line intersects with 20 or more fibers.

[0019] For the image with the above two straight lines drawn, for 20 or more fibers that intersect the first straight line, measure the length in the short direction of the fiber, that is, the fiber width, and the length in the long direction of the fiber, that is, the fiber length. Next, for 20 or more fibers that intersect the second straight line, measure the length in the short direction of the fiber, that is, the fiber width, and the length in the long direction of the fiber, that is, the fiber length. Calculate the total value by adding the total value of the fiber widths of 20 or more fibers read using the first straight line and the total value of the fiber widths of 20 or more fibers read using the second straight line. Divide the total value by the number of fibers for which the fiber width was read to calculate the average fiber width. Calculate the average fiber length in the same manner as the average fiber width.

[0020] As the cellulose fibers, cellulose fibers produced from plant raw materials may be used, or cellulose fibers obtained by chemically modifying cellulose fibers produced from plant raw materials may be used. For example, cellulose fibers obtained by pulverizing, TEMPO-oxidizing, or micronizing plant-derived raw materials such as pulp using cellulase are commercially available, and these may be utilized. The cellulose fibers can preferably be used in a powder dosage form.

[0021] As the mercapto-based silane coupling agent, for example, those having a silyl group (Si) and a mercapto group (SH) as a reactive group can be used. For example, those in which the silyl group is substituted with an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a hydrogen atom can be preferably used.

[0022] The mercapto group is said to undergo a thiourethanation reaction with a cyanate group to produce a reaction product. Also, the mercapto group is said to undergo an ene-thiol reaction with a double bond such as propylene to produce a reaction product. As the mercapto-based silane coupling agent, for example, those containing 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, 2-mercaptoethylmethyldimethoxysilane, 2-mercaptoethylmethyldiethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldiethoxysilane, 4-mercaptobutyltrimethoxysilane, or 4-mercaptobutyltriethoxysilane can be used.

[0023] When vulcanizing rubber, a vulcanizing agent is used. The vulcanizing agent is not particularly limited and any one can be used. Examples of the vulcanizing agent include sulfur donors such as sulfur, dithiomorpholine or alkylphenol disulfide, and organic peroxides such as peroxide.

[0024] Other components such as vulcanization accelerators, anti-aging agents, and process oils may be incorporated into the soles. Examples of vulcanization accelerators, though not particularly limited, include 2-mercaptobenzothiazole, 2-benzothiazolyl disulfide, 1,3-diphenylguanidine, N-(tert-butyl)-2-benzothiazole sulfenamide, tetramethylthiuram monosulfide, hexamethylenetetramine, 1,3-diethyl-2-thiourea, and ethylenethiourea (2-mercaptoimidazoline). Examples of anti-aging agents, though not particularly limited, include 2,5-di-tert-butyl-hydroquinone, mono(or di, or tri)(α-methylbenzyl)phenol, 2-mercaptobenzimidazole, and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine. It is also possible to use crack inhibitors in combination with anti-aging agents. Process oils are not particularly limited, but examples include naphthenic mineral oils, aromatic mineral oils, or paraffinic mineral oils.

[0025] If the sole of a shoe is too hard, it will be uncomfortable to wear and walk in, and your feet will tire easily. On the other hand, if the sole is too soft, it will wear down easily. For this reason, the hardness of the sole is preferably between 55 and 72 degrees. More preferably, the hardness of the sole is between 60 and 70 degrees. The hardness referred to here is measured in accordance with JIS K 6253-3:2012 and measured with a Type A durometer.

[0026] According to the present invention, the amount of wear determined by the William wear test method B of JIS K 6264-2 is 470 mm. 3 A shoe sole with a wear rate of 1000 revolutions per minute or less can be obtained. The lower limit of wear is not particularly limited, but 0 mm 3 Wear amount greater than 1000 rpm, or 240 mm 3 This can be used to illustrate wear amounts exceeding 1000 revolutions per minute.

[0027] The footwear to which the sole is fixed is not particularly limited. Examples include sneakers, tabi boots, leather shoes and other low-cut shoes; work boots, leather boots and rain boots and other long boots; or footwear without a heel cover, such as sandals and slippers.

[0028] Higher tear strength or tensile strength of shoe soles is always preferable. However, for everyday wear, it is preferable to have a lighter sole with lower density rather than excessive tear strength or tensile strength. In such cases, the tear strength may be 2.9 to 3.9 N / mm, and the tensile strength may be 5.0 to 9.0 MPa. The tear strength referred to here is the value obtained by testing according to method B of JIS K 6252-1:2015, using an angle-shaped test specimen without cuts. The tensile strength is the value obtained by testing according to method JIS K 6251:2017, using a dumbbell-shaped No. 2 test specimen.

[0029] For example, in applications where tear strength is required for the soles of work boots, the tear strength is preferably 4.8 to 6.8 N / mm. In applications where tensile strength is required for the soles of shoes, the tensile strength is preferably 14.0 to 18.0 MPa.

[0030] Shoe soles tend to be more comfortable when they are more stretchable. For this reason, it is preferable that the 200% tensile modulus value be between 4.0 and 6.0 MPa. The 200% modulus referred to here is the value of tensile stress when 200% elongation occurs, as determined by a test in accordance with the method of JIS K 6251:2017.

[0031] The amount of cellulose fiber to be blended is not particularly limited, but it is preferable to blend 5 to 30 parts by weight of cellulose fiber per 100 parts by weight of rubber. For solid fillers, it is preferable to blend 35 to 65 parts by weight per 100 parts by weight of rubber. For fillers having a hollow structure, it is preferable to blend 5 to 25 parts by weight per 100 parts by weight of rubber. For mercapto-silane coupling agents, it is preferable to blend 0.5 to 5.0 parts by weight per 100 parts by weight of rubber. [Examples]

[0032] The following describes embodiments of the present invention. The embodiments listed below are merely examples, and the technical scope of the present invention is not limited thereto.

[0033] [Example 1] A rubber composition for shoe soles was manufactured using the raw materials listed in the composition column of Table 1. In Example 1, 100 parts by weight of a mixture of natural rubber (NR), styrene-butadiene rubber (SBR), and butadiene rubber (BR) was used as the uncrosslinked rubber. The cellulose fiber labeled "Cellulose Fiber 1" in Table 1 was 10 parts by weight of commercially available cellulose fiber (PDP-01, manufactured by Chuetsu Pulp & Paper Co., Ltd.). This cellulose fiber was prepared by mixing a dispersion of cellulose fibers with a dispersant, then removing the liquid and pulverizing it. The average fiber length of this cellulose fiber was 1.0 μm or more, and the average fiber width was 3 to 200 nm. The filler labeled "Filler 1" in Table 1 had a BET specific surface area of ​​50 to 350 m² according to the catalog value. 2 50 parts by weight of wet silica ( / g) was used. Note that the wet silica was a commercially available product with the liquid content removed, and the amount used is calculated on a solid content basis. In Table 1, the silane coupling agent labeled "Coupling Agent 1" was 2.5 parts by weight of a commercially available mercapto-silane coupling agent.

[0034] Each of the above raw materials, along with 3 parts by weight of sulfur, 3 parts by weight of thiazole-based, sulfenamide-based, aldehyde ammonia-based, guanidine-based, and thiuram-based vulcanization accelerators, and 14 parts by weight of naphthenic process oil, were kneaded using a Banbury mixer and an open roll. The kneaded rubber composition was molded to dimensions suitable for each physical property test described later, and the molded pieces were heated and vulcanized to produce test pieces according to Example 1 for each physical property test.

[0035] [Examples 2 to 5] As shown in Table 2, test specimens for each physical property test in Examples 2 to 5 were manufactured using the same method as in Example 1, except that the mixing ratio of each raw material was changed. In Table 2, the cellulose fiber labeled "Cellulose Fiber 2" is a commercially available cellulose fiber (ARBOCEL FIF400) manufactured by Rettenmeyer Japan Co., Ltd., and the same applies to Table 1. Similarly, the cellulose fiber labeled "Cellulose Fiber 3" in Table 2 is a commercially available cellulose fiber (ARBOCEL BE600-30) manufactured by Rettenmeyer Japan Co., Ltd., and the same applies to Table 1. The silane cup coupling agent labeled "Coupling Agent 2" in Table 2 is a commercially available sulfide-based silane coupling agent, and the same applies to Table 1. The average fiber length and average fiber width of Cellulose Fiber 2 are 2000 μm and 35 μm, respectively. The average fiber length and average fiber width of Cellulose Fiber 3 are 30 μm and 18 μm, respectively.

[0036] [Comparative Examples 1 to 4, Comparative Examples 5 to 7] As shown in Table 1, test specimens for Comparative Examples 1 to 4 for each physical property test were manufactured in the same manner as in Example 1, except that the mixing ratio of each raw material was changed. Similarly, as shown in Table 2, test specimens for Comparative Examples 5 to 7 for each physical property test were manufactured in the same manner as in Example 1, except that the mixing ratio of each raw material was changed.

[0037] [Examples 6 to 8, Comparative Examples 8 to 10] As shown in Table 3, test specimens for each physical property test in Examples 6 to 8 were manufactured using the same method as in Example 1, except that the mixing ratio of each raw material was changed. Similarly, as shown in Table 3, test specimens for each physical property test in Comparative Examples 8 to 10 were manufactured using the same method as in Example 1, except that the mixing ratio of each raw material was changed.

[0038] The following physical property tests were performed on each test specimen manufactured using the method described above.

[0039] [Hardness measurement] Hardness was measured according to the method of JIS K 6253-3:2012. Test specimens were prepared according to the method of JIS K 6250. A Type A durometer manufactured by Nishitokyo Seimitsu Co., Ltd. was used.

[0040] [Tear strength] Tear strength was measured in accordance with the method of JIS K 6252-1:2015. Tear strength was determined using test method B with an angle-shaped test specimen without cuts.

[0041] [Tensile test] In accordance with the method of JIS K 6251:2017, the tensile elongation, 100% tensile modulus, 200% tensile modulus, 300% tensile modulus, and tensile strength were determined. A dumbbell-shaped specimen (Type 2) was used. The tensile elongation corresponds to the "elongation at break" in the JIS test, and the 100% tensile modulus corresponds to the "tensile stress at a specified elongation" in the JIS test, and is the value obtained by dividing the tensile force when the specimen is given 100% elongation by the cross-sectional area of ​​the specimen before the test. The 200% tensile modulus and 300% tensile modulus are obtained by replacing 100% with 200% and 300%, respectively. The tensile strength corresponds to the "tensile strength" in the JIS test.

[0042] [Abrasion test] The abrasion resistance of each of the above test specimens was investigated using Method B with a Williams abrasion tester as specified in JIS K 6264-2:2005.

[0043] The composition and physical property test results for each of the above examples and comparative examples are shown in Tables 1 to 3 below.

[0044] [Table 1]

[0045] [Table 2]

[0046] [Table 3]

[0047] The test specimens for Examples 1 to 5 shown in Tables 1 and 2 contain rubber, cellulose fibers, a filler, and a mercapto-silane coupling agent, and it can be seen that the abrasion resistance of the test specimens is improved compared to the test specimens for Comparative Examples 1 to 6.

[0048] Comparing the wear amount of the test specimen in Comparative Example 7 with the wear amount of Comparative Example 3, which has cellulose fibers added to the composition of Comparative Example 7, it can be seen that the wear resistance of the test specimen in Comparative Example 3, which has only cellulose fibers added, is reduced. The comparison of Comparative Examples 9 and 10 also shows that the addition of cellulose fibers reduces wear resistance.

[0049] A comparison of the test specimens from Example 1, Comparative Example 3, Comparative Example 4, and Comparative Example 5 shows that by compounding a mercapto-silane coupling agent, cellulose fibers, and filler into the rubber, the abrasion resistance of the test specimens is improved compared to test specimens containing cellulose fibers, filler, and rubber but no mercapto-silane coupling agent, test specimens containing a mercapto-silane coupling agent, filler, and rubber but no cellulose fibers, and test specimens containing a mercapto-silane coupling agent, cellulose fibers, and filler but with a small amount of filler.

[0050] Furthermore, a comparison of the test specimen from Example 1 with the test specimen from Comparative Example 1 or Comparative Example 2 shows that the test specimen containing a mercapto-silane coupling agent, filler, cellulose fibers, and rubber exhibits improved abrasion resistance compared to the test specimen from Comparative Example 1 or Comparative Example 2, which contains a sulfide-based silane coupling agent, filler, cellulose fibers, and rubber.

[0051] A comparison of the test specimens from Example 1 and Example 4 shows that when the average fiber width of cellulose fibers exceeds 35 μm, the abrasion resistance of the sole improves, but the sole also becomes harder. A comparison of the test specimens from Example 1 and Example 5 shows that incorporating so-called nanocellulose fibers, which have an average fiber width of less than 1000 nm, improves the abrasion resistance of the sole and prevents the sole from becoming excessively hard, compared to incorporating cellulose fibers with a medium fiber length, such as an average fiber width of 18 μm. A comparison of the test specimens from Example 1 and Example 4 or Example 5 also shows that incorporating nanocellulose fibers can improve the strength of the sole while suppressing the increase in hardness.

[0052] It is known that compounding glass balloons into rubber hardens the sole and significantly reduces its abrasion resistance. However, the test specimens in Examples 6 to 8 demonstrate high abrasion resistance despite the inclusion of glass balloons. The specific gravity of the test specimens in Examples 6 to 8 is lower than that of the test specimens in Examples 1 to 5. For example, if the sole of one shoe (right or left) is constructed using the test specimen from Example 1, it will weigh approximately 142g. On the other hand, if the sole of one shoe (right or left) is constructed using the test specimen from Example 1, a lightweight sole weighing approximately 120g can be constructed.

[0053] The wear results for Comparative Example 5 show that reducing the amount of filler reduces wear resistance. The wear results for Example 6 show that adding a filler with a hollow structure in addition to a solid filler can prevent a decrease in wear resistance.

Claims

1. A shoe sole containing vulcanized non-foamed rubber, a filler, cellulose fiber powder, and a mercapto-silane coupling agent, The following is a mixture containing 5 to 30 parts by weight of cellulose fiber powder per 100 parts by weight of the rubber: The wear amount determined by the Williams abrasion test method B of JIS K 6264-2 was 470 mm. ３ / 1000 rpm or less, Shoe soles with a hardness of 60-72 as measured with a Type A durometer in accordance with JIS K 6253-3:2012.

2. The sole of a shoe according to claim 1, wherein the cellulose fiber has an average fiber width of 500 μm or less.

3. The sole of a shoe according to claim 1 or 2, wherein the filler contains a hollow-structured filler.

4. The sole of the shoe according to any one of claims 1 to 3, wherein the specific gravity of the sole is 1.3 or less.

5. Footwear comprising a sole according to any one of claims 1 to 4.

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