A wear-resistant and anti-skid shoe sole and a preparation method thereof

Abstract

The present application relates to the field of shoes, and particularly relates to a preparation method of wear-resistant and anti-skid shoe sole, comprising the following steps: S1: polyurethane-acrylate copolymer, modified phenolic resin, stearic acid, zinc oxide, calcium stearate, vinyl silicone oil, ethylenediamine tetraacetic acid, magnesium oxide and AC foaming agent are uniformly mixed in an internal mixer, and continue to be mixed, after opening, granulation, room temperature standing treatment, and a molding masterbatch A is obtained; modified polyurethane, stearic acid, zinc oxide, vinyl silicone oil and ethylenediamine tetraacetic acid are mixed, and uniformly mixed in an internal mixer, and then granulation, room temperature standing treatment, and a molding masterbatch B is obtained; S2: the molding masterbatch A is put into a foaming mold for die forming, and then the molding masterbatch B is added, the mold is closed and heated, vulcanization treatment is carried out, and room temperature standing treatment is carried out, and a wear-resistant and anti-skid shoe sole is obtained. The wear-resistant and anti-skid shoe sole and the preparation method thereof have excellent anti-skid performance, and also have excellent wear-resistant performance.

Description

Technical Field

[0001] This invention relates to the field of footwear, specifically to a wear-resistant and non-slip shoe sole and its preparation method. Background Technology

[0002] The slip resistance of shoe soles directly affects the comfort and safety of consumers when wearing shoes. Currently, more and more consumers are enthusiastic about outdoor off-road sports, but when hiking or climbing on rugged mountain trails, it's inevitable to encounter wet surfaces. On wet, slippery surfaces, shoes with poor slip resistance can easily cause consumers to slip and fall. Existing sports shoe materials use EVA foam, which improves the product's elasticity, but it easily reduces the product's abrasion resistance, thus affecting its usability. Therefore, considering the above sports scenarios, consumers demand abrasion-resistant and slip-resistant performance from sports shoe soles to provide sufficient safety protection for more consumers. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a wear-resistant and anti-slip shoe sole and its preparation method, which has excellent anti-slip performance and excellent wear resistance.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for preparing a wear-resistant and non-slip shoe sole includes the following steps:

[0006] S1: Mix 40-50 parts by weight of polyurethane-acrylate copolymer, 20-30 parts by weight of modified phenolic resin, 3-5 parts by weight of stearic acid, 1-4 parts by weight of zinc oxide, 4-8 parts by weight of calcium stearate, 5-8 parts by weight of vinyl silicone oil, 10-15 parts by weight of ethylenediaminetetraacetic acid, 1-3 parts by weight of magnesium oxide and 1-3 parts by weight of AC foaming agent in an internal mixer at 60-70°C for 30-60 min, and continue mixing at 90-95°C for 15-20 min. After open milling, granulate and let stand at room temperature for 20-24 h to obtain molding masterbatch A.

[0007] Mix 20-30 parts by weight of modified polyurethane, 2-4 parts by weight of stearic acid, 3-6 parts by weight of zinc oxide, 5-8 parts by weight of vinyl silicone oil and 10-15 parts by weight of ethylenediaminetetraacetic acid, mix them evenly in an internal mixer at 40-50°C for 30-60 minutes, then granulate and let stand at room temperature for 20-24 hours to obtain molding masterbatch B.

[0008] S2: Place molding masterbatch A into a foaming mold and press it into shape. Then add molding masterbatch B, close the mold and heat it up. The mold closing pressure is 15-25MPa. Heat it up to 180-200℃ and vulcanize for 8-15 minutes. Then cool it down and let it stand at room temperature for 20-24 hours to obtain a wear-resistant and non-slip shoe sole.

[0009] Preferably, the preparation method of the modified phenolic resin in step S1 is as follows: phenol, KH-907 and dibutyltin dilaurate are mixed and stirred at 70-80°C for 3-4 hours under a nitrogen atmosphere. A 25% sodium hydroxide solution is added to adjust the pH of the reaction system to 8-9. Formaldehyde is then added and the reaction is continued at 70-90°C for 1-2 hours to obtain the modified phenolic resin.

[0010] Preferably, the weight ratio of phenol, KH-907, dibutyltin dilaurate, and formaldehyde is 3:4:1:3.

[0011] Preferably, the preparation method of the modified polyurethane in step S1 is as follows:

[0012] S11: Preparation of chain reaction intermediates and polyurethane prepolymers;

[0013] S12: Mix polyurethane prepolymer, dimethylolpropionic acid, 2,2'-diaminodiphenyl disulfide and chain reaction intermediate, react at 70-80℃ for 2-4 hours, cool to 30-40℃, add triethylamine and N,N-dimethylformamide, and continue the reaction for 30-40 minutes to obtain modified polyurethane.

[0014] Preferably, the weight ratio of the polyurethane prepolymer, dimethylolpropionic acid, 2,2'-diaminodiphenyl disulfide, chain reaction intermediate, triethylamine, and N,N-dimethylformamide is 1:2:2:1:2:3.

[0015] Preferably, the preparation method of the chain reaction intermediate in step S11 is as follows: guanidine carbonate, α-acetyl-γ-butyrolactone, ethanol and triethylamine are mixed and reacted at 70-80℃ for 12-16h, cooled to room temperature, washed, filtered and dried to obtain the chain reaction intermediate.

[0016] Preferably, the weight ratio of guanidine carbonate, α-acetyl-γ-butyrolactone, ethanol and triethylamine is 1:1:2:3.

[0017] Preferably, the preparation method of the polyurethane prepolymer in step S11 is as follows: polytetramethylene ether diol, isophorone diisocyanate and dibutyltin dilaurate are mixed and reacted at 70-80℃ for 2-3 hours to obtain the polyurethane prepolymer.

[0018] Preferably, the weight ratio of polytetramethylene ether diol, isophorone diisocyanate, and dibutyltin dilaurate is 2:2:1.

[0019] A wear-resistant and non-slip shoe sole is prepared by the above-described preparation method, and the surface of the shoe sole is also provided with decorative inserts.

[0020] The addition of modified phenolic resin in this invention increases the branching degree of the resin molecular structure through the introduction of organosilicon, thereby increasing the effective contact area with the components and enhancing the curing and cross-linking tendency. This also strengthens the interfacial bonding, ultimately forming a cross-linked three-dimensional network structure. This results in an anisotropic structure with a larger specific surface area, increasing the anisotropic contact sites on the sole and improving anti-slip performance. Furthermore, this invention introduces multiple hydrogen bonds into the polyurethane through the preparation of chain reaction intermediates, establishing a reversible multiple hydrogen bond physical cross-linking network. This forms a hydrogen bond network structure that interacts with specific groups in the polymer chain, increasing the internal density of the components through strong hydrogen bond interactions and enhancing the wear resistance of the material. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, it should be specifically noted that the raw materials and equipment of the present invention are all commercially available and will not be listed one by one. Among them, the raw materials of the present invention are all commercially available and well known to those skilled in the art, and will not be described in detail. Example 1

[0022] A method for preparing a wear-resistant and non-slip shoe sole includes the following steps:

[0023] S1: 40 parts by weight of polyurethane-acrylate copolymer, 20 parts by weight of modified phenolic resin, 3 parts by weight of stearic acid, 1 part by weight of zinc oxide, 4 parts by weight of calcium stearate, 5 parts by weight of vinyl silicone oil, 10 parts by weight of ethylenediaminetetraacetic acid, 1 part by weight of magnesium oxide and 1 part by weight of AC foaming agent are mixed evenly in an internal mixer at 60°C for 30 min, and then mixed at 90°C for 15 min. After open milling, the mixture is granulated and allowed to stand at room temperature for 20 h to obtain molding masterbatch A.

[0024] The specific preparation method of the modified phenolic resin is as follows: phenol, KH-907 and dibutyltin dilaurate are mixed and stirred at 70°C for 3 hours under a nitrogen atmosphere. A 25% sodium hydroxide solution is added to adjust the pH of the reaction system to 8-9. Then formaldehyde is added. The weight ratio of phenol, KH-907, dibutyltin dilaurate and formaldehyde is 3:4:1:3. The reaction is continued at 70°C for 1 hour to obtain the modified phenolic resin.

[0025] 20 parts by weight of modified polyurethane, 2 parts by weight of stearic acid, 3 parts by weight of zinc oxide, 5 parts by weight of vinyl silicone oil and 10 parts by weight of ethylenediaminetetraacetic acid were mixed and mixed evenly in an internal mixer at 40°C for 30 min. Then the mixture was granulated and allowed to stand at room temperature for 20 h to obtain molding masterbatch B.

[0026] The specific preparation method of the modified polyurethane is as follows:

[0027] S11: Preparation of chain reaction intermediate: Guanidine carbonate, α-acetyl-γ-butyrolactone, ethanol and triethylamine were mixed in a weight ratio of 1:1:2:3 and reacted at 70°C for 12 h. After cooling to room temperature, the mixture was washed, filtered and dried to obtain the chain reaction intermediate.

[0028] Preparation of polyurethane prepolymer: Polytetramethylene ether glycol, isophorone diisocyanate and dibutyltin dilaurate were mixed in a weight ratio of 2:2:1 and reacted at 70°C for 2 hours to obtain polyurethane prepolymer.

[0029] S12: Polyurethane prepolymer, dimethylolpropionic acid, 2,2'-diaminodiphenyl disulfide and chain reaction intermediate are mixed and reacted at 70°C for 2 hours. After cooling to 30°C, triethylamine and N,N-dimethylformamide are added, and the reaction is continued for 30 minutes. The weight ratio of polyurethane prepolymer, dimethylolpropionic acid, 2,2'-diaminodiphenyl disulfide, chain reaction intermediate, triethylamine and N,N-dimethylformamide is 1:2:2:1:2:3, to obtain modified polyurethane.

[0030] S2: Place molding masterbatch A into a foaming mold and press it into shape. Then add molding masterbatch B of the same weight as molding masterbatch A, close the mold and heat it up. The mold closing pressure is 15MPa. Heat it up to 180℃ and vulcanize it for 8 minutes. Then cool it down and let it stand at room temperature for 20 hours to obtain a wear-resistant and non-slip shoe sole.

[0031] A wear-resistant and non-slip shoe sole is prepared by the above-mentioned preparation method, and the surface of the shoe sole is also provided with decorative inlays (such as logos, patterned fabrics, gradient color materials, etc.). Example 2

[0032] A method for preparing a wear-resistant and non-slip shoe sole includes the following steps:

[0033] S1: 45 parts by weight of polyurethane-acrylate copolymer, 25 parts by weight of modified phenolic resin, 4 parts by weight of stearic acid, 3 parts by weight of zinc oxide, 6 parts by weight of calcium stearate, 7 parts by weight of vinyl silicone oil, 12 parts by weight of ethylenediaminetetraacetic acid, 2 parts by weight of magnesium oxide and 2 parts by weight of AC foaming agent are mixed evenly in an internal mixer at 65°C for 45 min, and then mixed at 92°C for 18 min. After open milling, the mixture is granulated and allowed to stand at room temperature for 22 h to obtain molding masterbatch A.

[0034] The specific preparation method of the modified phenolic resin is as follows: phenol, KH-907 and dibutyltin dilaurate are mixed and stirred at 75°C for 3.5 h under a nitrogen atmosphere. A 25% sodium hydroxide solution is added to adjust the pH of the reaction system to 8-9. Then formaldehyde is added. The weight ratio of phenol, KH-907, dibutyltin dilaurate and formaldehyde is 3:4:1:3. The reaction is continued at 80°C for 1.5 h to obtain the modified phenolic resin.

[0035] 25 parts by weight of modified polyurethane, 3 parts by weight of stearic acid, 5 parts by weight of zinc oxide, 7 parts by weight of vinyl silicone oil and 12 parts by weight of ethylenediaminetetraacetic acid were mixed and mixed evenly in an internal mixer at 45°C for 45 min. After mixing, the mixture was granulated and allowed to stand at room temperature for 22 h to obtain molding masterbatch B.

[0036] The specific preparation method of the modified polyurethane is as follows:

[0037] S11: Preparation of chain reaction intermediate: Guanidine carbonate, α-acetyl-γ-butyrolactone, ethanol and triethylamine were mixed in a weight ratio of 1:1:2:3 and reacted at 75°C for 14 h. After cooling to room temperature, the mixture was washed, filtered and dried to obtain the chain reaction intermediate.

[0038] Preparation of polyurethane prepolymer: Polytetramethylene ether glycol, isophorone diisocyanate and dibutyltin dilaurate were mixed in a weight ratio of 2:2:1 and reacted at 75°C for 2.5 h to obtain polyurethane prepolymer;

[0039] S12: Polyurethane prepolymer, dimethylolpropionic acid, 2,2'-diaminodiphenyl disulfide and chain reaction intermediate are mixed and reacted at 75°C for 3 hours. After cooling to 35°C, triethylamine and N,N-dimethylformamide are added, and the reaction is continued for 35 minutes. The weight ratio of polyurethane prepolymer, dimethylolpropionic acid, 2,2'-diaminodiphenyl disulfide, chain reaction intermediate, triethylamine and N,N-dimethylformamide is 1:2:2:1:2:3, to obtain modified polyurethane.

[0040] S2: Place molding masterbatch A into a foaming mold and press it into shape. Then add molding masterbatch B of the same weight as molding masterbatch A, close the mold and heat it up. The mold closing pressure is 20MPa. Heat it up to 190℃ and vulcanize it for 12 minutes. Then cool it down and let it stand at room temperature for 22 hours to obtain a wear-resistant and non-slip shoe sole.

[0041] A wear-resistant and non-slip shoe sole is prepared by the above-mentioned preparation method, and the surface of the shoe sole is also provided with decorative inlays (such as logos, patterned fabrics, gradient color materials, etc.). Example 3

[0042] A method for preparing a wear-resistant and non-slip shoe sole includes the following steps:

[0043] S1: 50 parts by weight of polyurethane-acrylate copolymer, 30 parts by weight of modified phenolic resin, 5 parts by weight of stearic acid, 4 parts by weight of zinc oxide, 8 parts by weight of calcium stearate, 8 parts by weight of vinyl silicone oil, 15 parts by weight of ethylenediaminetetraacetic acid, 3 parts by weight of magnesium oxide and 3 parts by weight of AC foaming agent are mixed evenly in an internal mixer at 70°C for 60 min, and then mixed again at 95°C for 20 min. After open milling, the mixture is granulated and allowed to stand at room temperature for 24 h to obtain molding masterbatch A.

[0044] The specific preparation method of the modified phenolic resin is as follows: phenol, KH-907 and dibutyltin dilaurate are mixed and stirred at 80°C for 4 hours under a nitrogen atmosphere. A 25% sodium hydroxide solution is added to adjust the pH of the reaction system to 9. Then formaldehyde is added. The weight ratio of phenol, KH-907, dibutyltin dilaurate and formaldehyde is 3:4:1:3. The reaction is continued at 90°C for 2 hours to obtain the modified phenolic resin.

[0045] 30 parts by weight of modified polyurethane, 4 parts by weight of stearic acid, 6 parts by weight of zinc oxide, 8 parts by weight of vinyl silicone oil and 15 parts by weight of ethylenediaminetetraacetic acid were mixed and mixed evenly in an internal mixer at 50°C for 60 min. Then, the mixture was granulated and allowed to stand at room temperature for 24 h to obtain molding masterbatch B.

[0046] The specific preparation method of the modified polyurethane is as follows:

[0047] S11: Preparation of chain reaction intermediate: Guanidine carbonate, α-acetyl-γ-butyrolactone, ethanol and triethylamine were mixed in a weight ratio of 1:1:2:3 and reacted at 80°C for 16 h. After cooling to room temperature, the mixture was washed, filtered and dried to obtain the chain reaction intermediate.

[0048] Preparation of polyurethane prepolymer: Polytetramethylene ether glycol, isophorone diisocyanate and dibutyltin dilaurate were mixed in a weight ratio of 2:2:1 and reacted at 80°C for 3 hours to obtain polyurethane prepolymer.

[0049] S12: Polyurethane prepolymer, dimethylolpropionic acid, 2,2'-diaminodiphenyl disulfide and chain reaction intermediate are mixed and reacted at 80°C for 4 hours. After cooling to 40°C, triethylamine and N,N-dimethylformamide are added, and the reaction is continued for 40 minutes. The weight ratio of polyurethane prepolymer, dimethylolpropionic acid, 2,2'-diaminodiphenyl disulfide, chain reaction intermediate, triethylamine and N,N-dimethylformamide is 1:2:2:1:2:3, to obtain modified polyurethane.

[0050] S2: Place molding masterbatch A into a foaming mold and press it into shape. Then add molding masterbatch B of the same weight as molding masterbatch A, close the mold and heat it up. The mold closing pressure is 25MPa. Heat it up to 200℃ and vulcanize it for 15 minutes. Then cool it down and let it stand at room temperature for 24 hours to obtain a wear-resistant and non-slip shoe sole.

[0051] A wear-resistant and non-slip shoe sole is prepared by the above-mentioned preparation method, and the surface of the shoe sole is also provided with decorative inlays (such as logos, patterned fabrics, gradient color materials, etc.).

[0052] Comparative Example 1:

[0053] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that the phenolic resin and polyurethane are not modified. Specifically:

[0054] A method for preparing a wear-resistant and non-slip shoe sole includes the following steps:

[0055] S1: 40 parts by weight of polyurethane-acrylate copolymer, 20 parts by weight of phenolic resin, 3 parts by weight of stearic acid, 1 part by weight of zinc oxide, 4 parts by weight of calcium stearate, 5 parts by weight of vinyl silicone oil, 10 parts by weight of ethylenediaminetetraacetic acid, 1 part by weight of magnesium oxide and 1 part by weight of AC foaming agent are mixed evenly in an internal mixer at 60°C for 30 min, and then mixed at 90°C for 15 min. After open milling, the mixture is granulated and allowed to stand at room temperature for 20 h to obtain molding masterbatch A.

[0056] 20 parts by weight of polyurethane, 2 parts by weight of stearic acid, 3 parts by weight of zinc oxide, 5 parts by weight of vinyl silicone oil and 10 parts by weight of ethylenediaminetetraacetic acid are mixed and mixed evenly in an internal mixer at 40°C for 30 minutes. Then, the mixture is granulated and allowed to stand at room temperature for 20 hours to obtain molding masterbatch B.

[0057] S2: Place molding masterbatch A into a foaming mold and press it into shape. Then add molding masterbatch B of the same weight as molding masterbatch A, close the mold and heat it up. The mold closing pressure is 15MPa. Heat it up to 180℃ and vulcanize it for 8 minutes. Then cool it down and let it stand at room temperature for 20 hours to obtain a wear-resistant and non-slip shoe sole.

[0058] A wear-resistant and non-slip shoe sole is prepared by the above-mentioned preparation method, and the surface of the shoe sole is also provided with decorative inlays (such as logos, patterned fabrics, gradient color materials, etc.).

[0059] The following tests were conducted on the anti-slip effect and abrasion resistance of the soles obtained in Examples 1-3, the commercially available soles from Wangdu County Jiaoshang Shoes Co., Ltd., and the soles obtained in Comparative Example 1.

[0060] Anti-slip coefficient: Tested according to the methods specified in GB / T3903.6-2017 and SATRA TM144:2021.

[0061] Abrasion resistance: Tested according to the method specified in national standard GB / T 9867-2008.

[0062] Tear strength: Tested according to national standard GB / T 10808-2006.

[0063] Table 1: Test data of Examples 1-3, commercially available shoe soles, and the shoe sole of Comparative Example 1:

[0064]

[0065] As can be seen from the table above, the soles of Examples 1-3 have better anti-slip performance than Comparative Example 1 and commercially available soles (simultaneously meeting the requirements of dynamic wet anti-slip coefficient ≥0.40 and ice surface anti-slip coefficient ≥0.30), and also have excellent wear resistance.

[0066] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a wear-resistant and non-slip shoe sole, characterized in that, Includes the following steps: S1: Mix 40-50 parts by weight of polyurethane-acrylate copolymer, 20-30 parts by weight of modified phenolic resin, 3-5 parts by weight of stearic acid, 1-4 parts by weight of zinc oxide, 4-8 parts by weight of calcium stearate, 5-8 parts by weight of vinyl silicone oil, 10-15 parts by weight of ethylenediaminetetraacetic acid, 1-3 parts by weight of magnesium oxide and 1-3 parts by weight of AC foaming agent in an internal mixer at 60-70°C for 30-60 min, and continue mixing at 90-95°C for 15-20 min. After open milling, granulate and let stand at room temperature for 20-24 h to obtain molding masterbatch A. Mix 20-30 parts by weight of modified polyurethane, 2-4 parts by weight of stearic acid, 3-6 parts by weight of zinc oxide, 5-8 parts by weight of vinyl silicone oil and 10-15 parts by weight of ethylenediaminetetraacetic acid, mix them evenly in an internal mixer at 40-50°C for 30-60 minutes, then granulate and let stand at room temperature for 20-24 hours to obtain molding masterbatch B. S2: Place molding masterbatch A into a foaming mold and press it into shape. Then add molding masterbatch B, close the mold and heat it up. The mold closing pressure is 15-25MPa. Heat it up to 180-200℃ and vulcanize it for 8-15 minutes. Then cool it down and let it stand at room temperature for 20-24 hours to obtain a wear-resistant and non-slip shoe sole. The specific preparation method of the modified phenolic resin in step S1 is as follows: phenol, KH-907 and dibutyltin dilaurate are mixed and stirred at 70-80℃ for 3-4 hours under nitrogen atmosphere. Sodium hydroxide solution with a mass fraction of 25% is added to adjust the pH of the reaction system to 8-9. Formaldehyde is then added and the reaction is continued at 70-90℃ for 1-2 hours to obtain the modified phenolic resin. The specific preparation method of the modified polyurethane in step S1 is as follows: S11: Preparation of chain reaction intermediates and polyurethane prepolymers; S12: Mix polyurethane prepolymer, dimethylolpropionic acid, 2,2'-diaminodiphenyl disulfide and chain reaction intermediate, react at 70-80℃ for 2-4h, cool to 30-40℃, add triethylamine and N,N-dimethylformamide, and continue the reaction for 30-40min to obtain modified polyurethane. The preparation method of the chain reaction intermediate in step S11 is as follows: Guanidine carbonate, α-acetyl-γ-butyrolactone, ethanol and triethylamine are mixed and reacted at 70-80℃ for 12-16h. After cooling to room temperature, the mixture is washed, filtered and dried to obtain the chain reaction intermediate.

2. The method for preparing the wear-resistant and non-slip shoe sole as described in claim 1, characterized in that: The weight ratio of phenol, KH-907, dibutyltin dilaurate, and formaldehyde is 3:4:1:

3.

3. The method for preparing the wear-resistant and non-slip shoe sole as described in claim 1, characterized in that: The polyurethane prepolymer, dimethylolpropionic acid, 2,2'-diaminodiphenyl disulfide, chain reaction intermediate, triethylamine, and N,N-dimethylformamide are in a weight ratio of 1:2:2:1:2:

3.

4. The method for preparing the wear-resistant and non-slip shoe sole as described in claim 1, characterized in that: The weight ratio of guanidine carbonate, α-acetyl-γ-butyrolactone, ethanol and triethylamine is 1:1:2:

3.

5. The method for preparing the wear-resistant and non-slip shoe sole as described in claim 1, characterized in that: The specific method for preparing the polyurethane prepolymer in step S11 is as follows: polytetramethylene ether diol, isophorone diisocyanate and dibutyltin dilaurate are mixed and reacted at 70-80℃ for 2-3 hours to obtain the polyurethane prepolymer.

6. The method for preparing the wear-resistant and non-slip shoe sole as described in claim 5, characterized in that: The weight ratio of polytetramethylene ether diol, isophorone diisocyanate, and dibutyltin dilaurate is 2:2:

1.

7. A wear-resistant and non-slip shoe sole, characterized in that, The sole is prepared by the method described in claim 1, and the surface of the sole is further provided with decorative inserts.

Images