A high-bio-based content shoe sole rubber material and a method of making the same

Abstract

The application discloses a high-bio-based-content shoe sole rubber material and a preparation method thereof, and belongs to the technical field of rubber materials.The high-bio-based-content shoe sole rubber material comprises the following components in mass parts: natural rubber 20-30 parts, modified polyhydroxybutyrate 20-30 parts, modified bio-based powder 20-30 parts, biodegradation aid 5-8 parts, compatibilizer 6-12 parts, reinforcing agent 10-12 parts, coupling agent 2-8 parts, accelerator 2-4 parts, antioxidant 3 parts, crosslinking agent 2-4 parts, wear-resistant reinforcing agent 2 parts and processing aid 2 parts.The wood vinegar modified polyhydroxybutyrate, the tannic acid treated bio-based powder and the synergistic effect of the compounded compatibilizer / degradation aid are used, so that the wet friction coefficient, the tensile strength and the degradation rate all reach the leading level in the industry on the premise of maintaining high bio-based content.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rubber materials, and particularly relates to a high-bio-based-content shoe sole rubber material and a preparation method thereof. BACKGROUND

[0002] As a core functional component of footwear products, shoe sole material is directly related to wearing comfort, sports safety and environmental sustainability. However, the current mainstream shoe sole material is still mainly petroleum-based synthetic rubber, thermoplastic polyurethane and ethylene-vinyl acetate copolymer. Although these materials have certain wear resistance and processing convenience, they have problems such as dependence on non-renewable raw materials, high carbon emissions in the production process and difficulty in degradation after being discarded, which seriously restrict the sustainable development of the industry. Therefore, the development of bio-based shoe sole rubber material has become a new research hotspot.

[0003] However, in the performance dimension of shoe sole material, the lack of wet skid resistance is the key to restricting the application of bio-based materials. Studies have shown that the dynamic friction coefficient of existing bio-based shoe soles on a wet ceramic tile surface is generally less than 0.5 (SATRA TM144 standard), which is about 30% lower than that of traditional petroleum-based materials (0.6-0.7), and is particularly prone to slipping accidents in rainy and snowy environments or oily ground. This defect is due to the strong hydrophilicity of the surface of bio-based materials and the lack of rigid support points in the microtexture, making it difficult for water film to quickly drain.

[0004] Breaking through the short board of wet skid resistance of bio-based shoe soles has urgent technical and commercial value. From the safety dimension, according to the European Union standard, the wet friction coefficient of safety shoes needs to be greater than or equal to 0.7. Therefore, under the premise of maintaining high bio-based content and degradability, developing a shoe sole rubber material with a wet friction coefficient greater than or equal to 0.5 has become a technical problem that the industry urgently needs to overcome. SUMMARY

[0005] In order to develop a shoe sole rubber material with a wet friction coefficient greater than or equal to 0.5 under the premise of maintaining high bio-based content and degradability, the application provides a high-bio-based-content shoe sole rubber material and a preparation method thereof. Specifically, the technical scheme adopted by the application is as follows:

[0006] A high-bio-based-content shoe sole rubber material, comprising the following components in parts by mass:

[0007] 20-30 parts of natural rubber, 20-30 parts of modified polyhydroxybutyrate, 20-30 parts of modified bio-based powder, 5-8 parts of biodegradation aid, 6-12 parts of compatibilizer, 10-12 parts of reinforcing agent, 2-8 parts of coupling agent, 2-4 parts of accelerator, 3 parts of antioxidant, 2-4 parts of crosslinking agent, 2 parts of wear-resistant reinforcing agent, and 2 parts of processing aid.

[0008] Further, the modified polyhydroxybutyrate is prepared by the following steps:

[0009] A1, corn starch and plasticizer glycerol are mixed according to a mass ratio of 10:3, extruded and granulated at 120-130 DEG C, cooled, and granulated to obtain thermoplastic starch masterbatch;

[0010] A2, polyhydroxybutyric acid vinegar liquor is mixed and mixed at 155-160 DEG C for 5-10 min, then the thermoplastic starch masterbatch is added, heated to 165-170 DEG C and mixed for 8-10 min, then the temperature is lowered to 130-140 DEG C, and dicumyl peroxide is added and mixed for 3-5 min, and then cooled to room temperature to obtain modified polyhydroxybutyric acid.

[0011] Further, the corn starch and glycerol in A1 are mixed according to a mass ratio of 10:3.

[0012] Further, the mass ratio of polyhydroxybutyric acid, vinegar liquor, thermoplastic starch masterbatch, and dicumyl peroxide in A2 is 28-30:3-5:15-20:0.5-1.0.

[0013] Further, the modified bio-based powder is prepared by the following steps:

[0014] B1, anhydrous ethanol and silane coupling agent KH-550 are mixed according to a volume ratio of 19:1 to prepare a treatment solution, and then the chaff powder is dried in an oven at 105-110 DEG C for 2 h, after which the dried chaff powder is immersed in the treatment solution according to a solid-liquid ratio of 1:10, the system is heated to 60-65 DEG C and magnetically stirred at constant temperature for 30 min, during which ultrasonic treatment is started every 10 min for 5 min, after which the powder is separated by suction filtration, washed with anhydrous ethanol 3 times to remove physical adsorbents, and then placed in a vacuum dryer at 80-100 DEG C for 4-5 h to obtain silanized chaff powder;

[0015] B2, a tannic acid-water solution with a mass concentration of 0.5wt% is prepared, and then a 0.1mol / L NaOH solution is used to adjust the pH of the tannic acid-water solution to 5.0-5.2, after which a surface treatment solution is obtained;

[0016] B3, the surface treatment solution is sprayed on the surface of the silanized chaff powder using an airbrush at a flow rate of 0.2mL / min, and the spraying amount is controlled at 2.5%-5.0% of the mass of the silanized chaff powder, after which it is hot air cured, cooled, and then sieved through an 80 mesh sieve to obtain a modified bio-based powder.

[0017] Further, the biodegradation aid is a compound of polycaprolactone and polybutylene succinate according to a mass ratio of 1:1.

[0018] Further, the compatilizer is epoxy soybean oil and maleic anhydride grafted polylactic acid compounded according to a mass ratio of 2:1.

[0019] Further, the reinforcing agent is one of kaolin, bentonite and white carbon black.

[0020] Further, the coupling agent is one of KH-550, KH-560 and KH-570.

[0021] Further, the accelerator is one or two of triallyl isocyanurate and trimethylolpropane trimethacrylate compounded according to a mass ratio of 1:1.

[0022] Further, the antioxidant is one or two of antioxidant RD and antioxidant 4010NA compounded according to a mass ratio of 2:1.

[0023] Further, the crosslinking agent is one of 1,4-bis-tert-butyl peroxyisopropyl benzene, 1,1'-bis(tert-butyl peroxy)-3,3,5-trimethylcyclohexane and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0024] Further, the wear-resistant reinforcing agent is nano-cellulose whisker and bamboo charcoal powder compounded according to a mass ratio of 1:3.

[0025] Further, the processing aid is one of tributyl citrate and glyceryl stearate.

[0026] The application also provides a preparation method of the bio-based shoe sole material.

[0027] S1, according to the mass fraction, the raw materials are weighed, the natural rubber and the modified polyhydroxybutyrate are added into a mixer with a temperature of 120-140 DEG C and a rotation speed of 50 r / min, and mixed for 10-15 min, then the modified bio-based powder is added into the mixer, the temperature and the rotation speed are controlled to be unchanged, and mixed for 8-10 min to obtain a masterbatch;

[0028] S2, the biodegradation aid, the compatilizer, the reinforcing agent, the coupling agent, the accelerator, the antioxidant, the crosslinking agent, the wear-resistant reinforcing agent and the processing aid are sequentially added into the mixer containing the masterbatch in step S1 according to the mass fraction, the temperature and the rotation speed are controlled to be unchanged, and mixed for 5-10 min, then cooled to room temperature to obtain a mixture, the mixture is granulated in a granulator to obtain a sample;

[0029] S3, the sample obtained in step S2 is placed into a vulcanization forming machine, the vulcanization temperature is controlled to be 150-160 DEG C, the vulcanization time is controlled to be 3-4 h, then cooled to room temperature after the vulcanization is completed, the vulcanized material is taken out from the vulcanization forming machine to obtain a bio-based shoe sole material.

[0030] The beneficial effects obtained by the present application are as follows:

[0031] The present application aims to solve the three technical problems of low wet friction coefficient (generally <0.5), insufficient mechanical properties, and limited degradation efficiency of bio-based shoe sole materials in the background art. Through component innovation and process optimization, performance breakthroughs are achieved. The beneficial effects are described in detail below in combination with Table 1 test data:

[0032] (1) Significant improvement in wet friction coefficient:

[0033] The wet friction coefficient of existing bio-based shoe soles is less than 0.5, while the wet friction coefficient of Example 8 of the present application is 0.71±0.02, which is 44.9% higher than that of Comparative Example 7 (unmodified polyhydroxybutyrate matrix, 0.49). This improvement is due to the synergistic effect of double-interface modification:

[0034] a. Wood vinegar enhances the interfacial bonding of polyhydroxybutyrate: The wet friction coefficient of Comparative Example 3 (polyhydroxybutyrate modified without wood vinegar) is only 0.58, which is 18.3% lower than that of Example 8 (0.71). The organic acids in wood vinegar form a hydrogen bond network with the hydroxyl groups of starch, improving the compatibility of polyhydroxybutyrate and starch, reducing interface defects, and enhancing the water film discharge capacity.

[0035] b. Tannin acid hydrophobic coating optimizes surface properties: The wet friction coefficient of Comparative Example 4 (without tannin acid spraying) is 0.60, which is 15.5% lower than that of Example 8. Tannin acid spraying forms hydrogen bonds between the polyphenol hydroxyl groups and the rubber matrix, improving the surface hydrophobicity, while enhancing the powder-matrix bonding force and reducing wear and tear (Comparative Example 4 wear resistance 105mm 3 , Example 8 is 72mm 3 , improved by 31.4%).

[0036] Synergistic effect verification: The synergistic effect of wood vinegar and tannin acid treatment increases the wet friction coefficient from 0.49 of Comparative Example 7 to 0.71 of Example 8, with an increase of 44.9%, which is much higher than the improvement effect of a single component (such as Comparative Examples 3 / 4, only 0.58 / 0.60), proving the creativity of the synergistic effect between the innovative components.

[0037] (2) Synergistic optimization of mechanical properties and degradation efficiency:

[0038] The existing bio-based materials often face the contradiction between strength, toughness and degradation rate. The tensile strength of the embodiment 8 reaches 15.8 MPa, and the elongation at break is 360%, which is 4.6% and 63.6% higher than those of the comparative example 7 (15.1 MPa / 220%) respectively. The bi-continuous phase of starch-polyhydroxybutyrate in the modified polyhydroxybutyrate is reduced by dynamic crosslinking (dicumyl peroxide initiation) to reduce the crystallinity of polyhydroxybutyrate, and at the same time, the interfacial bonding force is improved. At the same time, the degradation aid is compounded to accelerate the decomposition: the degradation rate of the embodiment 8 is 73% (90 days of composting), which is 25.9% higher than that of the comparative example 5 (single polycaprolactone degradation aid, 58%). Polycaprolactone and polybutylene succinate are compounded at a ratio of 1:1 (embodiment 8) to form a complementary degradation mechanism: polybutylene succinate provides a microbial carbon source by rapid hydrolysis, and polycaprolactone slowly enzymatically degrades to extend the degradation period.

[0039] (3) Balance between high bio-based content and performance:

[0040] The existing high bio-based content often leads to performance degradation, while the bio-based content of the present application reaches 78.1% (embodiment 8, ASTM D6866), which is much higher than the industry level (50%~60%), and at the same time, it has excellent slip resistance, mechanical properties and environmental protection.

[0041] In summary, through the synergistic effect of wood vinegar modified polyhydroxybutyrate, tannic acid treated bio-based powder and compounded compatibilizer / degradation aid, the wet friction coefficient (0.71), tensile strength (15.8 MPa) and degradation rate (73%) all reach the industry leading level on the premise of maintaining high bio-based content (78.1%), solving the technical problem of "difficulty in balancing slip resistance, mechanical properties and environmental protection" in the prior art, and having significant industrial application value. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0043] Embodiment 1

[0044] Preparation of modified polyhydroxybutyrate:

[0045] A1, corn starch and plasticizer glycerol were mixed at a mass ratio of 10:3, and extruded and granulated in a twin-screw extruder at 120°C (screw rotation speed 60 rpm, L / D=40:1). After completion, cooling and granulation were performed to obtain thermoplastic starch masterbatch.

[0046] A2, put 28 parts (mass parts; same below) of polyhydroxybutyrate (melt index 8 g / 10 min) and 3 parts of wood vinegar into the internal mixer, heat the internal mixer to 155°C, mix at 50 rpm for 5 min, then add 15 parts of thermoplastic starch masterbatch to the internal mixer, heat the internal mixer to 165°C, and mix at 80 rpm for 8 min. During the mixing process, the acetic acid and phenolic substances in the wood vinegar form hydrogen bonds with the hydroxyl groups of the starch, and the ester groups (-COO-) of the polyhydroxybutyrate physically crosslink with the molecular chains of the starch through proton transfer. After completion, the internal mixer is cooled to 130°C at a cooling rate of 10°C / min, then 0.5 parts of dicumyl peroxide is added, and mixing is continued for 3 min. During this process, a bicontinuous phase structure is formed. After completion, cool to room temperature to obtain modified polyhydroxybutyrate.

[0047] Example 2

[0048] Preparation of modified polyhydroxybutyrate:

[0049] A1, mix corn starch and plasticizer glycerol at a mass ratio of 10:3, and extrude and granulate in a twin-screw extruder at 120°C (screw speed 60 rpm, L / D = 40:1). After completion, cool and cut into granules to obtain thermoplastic starch masterbatch.

[0050] A2, put 28 parts (mass parts; same below) of polyhydroxybutyrate (melt index 8 g / 10 min) and 3 parts of wood vinegar into the internal mixer, heat the internal mixer to 155°C, mix at 50 rpm for 5 min, then add 15 parts of thermoplastic starch masterbatch to the internal mixer, heat the internal mixer to 165°C, and mix at 80 rpm for 8 min. During the mixing process, the acetic acid and phenolic substances in the wood vinegar form hydrogen bonds with the hydroxyl groups of the starch, and the ester groups (-COO-) of the polyhydroxybutyrate physically crosslink with the molecular chains of the starch through proton transfer. After completion, the internal mixer is cooled to 130°C at a cooling rate of 10°C / min, then 0.5 parts of dicumyl peroxide is added, and mixing is continued for 3 min. During this process, a bicontinuous phase structure is formed. After completion, cool to room temperature to obtain modified polyhydroxybutyrate.

[0051] Example 3

[0052] Preparation of modified polyhydroxybutyrate:

[0053] A1, mix corn starch and plasticizer glycerol at a mass ratio of 10:3, and extrude and granulate in a twin-screw extruder at 130°C (screw speed 60 rpm, L / D = 40:1). After completion, cool and cut into granules to obtain thermoplastic starch masterbatch.

[0054] A2, into the internal mixer 30 parts (mass parts; same below) of polyhydroxybutyrate (melt index 8 g / 10 min) and 5 parts of vinegar, the internal mixer is heated to 160°C, 50 rpm mixing 10 min, then add 20 parts of thermoplastic starch masterbatch to the internal mixer, the internal mixer is heated to 170°C, the speed is increased to 80 rpm mixing 10 min, during the mixing process, the acetic acid and phenolic substances in the vinegar form hydrogen bonds with the hydroxyl groups of the starch, the ester groups (-COO-) of the polyhydroxybutyrate and the molecular chain of the starch form physical crosslinking through proton transfer, after completion, the internal mixer is cooled to 140°C at a cooling rate of 10°C / min, then 1.0 parts of dicumyl peroxide is added, and mixing is continued for 5 min, during which a bicontinuous phase structure is formed, after completion, it is cooled to room temperature to obtain modified polyhydroxybutyrate.

[0055] Comparative Example 1

[0056] Comparative Example 1 is a control group of Example 2, compared with Example 2, no vinegar is added in step A2 of Example 2, and the other raw materials, raw material amounts and preparation steps remain the same as in Example 2, and finally modified polyhydroxybutyrate is obtained.

[0057] Example 4

[0058] Preparation of modified bio-based powder:

[0059] B1, prepare a treatment solution by mixing anhydrous ethanol and silane coupling agent KH-550 in a volume ratio of 19:1, then dry the rice husk powder in an oven at 105°C for 2h, after completion, immerse the dried rice husk powder in the treatment solution at a solid-liquid ratio of 1:10, heat the system to 60°C, and then magnetically stir (speed 300 rpm) for 30 min, during which ultrasonic treatment is started every 10 min for 5 min (power 200W), after completion, filter separation and collect the powder, wash with anhydrous ethanol 3 times to remove physical adsorption, then place in a vacuum dryer at 80°C for 4h to obtain silanized rice husk powder.

[0060] B2, prepare a tannic acid-water solution with a mass concentration of 0.5wt%, then adjust the pH of the tannic acid-water solution to 5.0 with 0.1mol / L NaOH solution, after completion, obtain a surface treatment solution.

[0061] B3, spread the silanized rice husk powder on a stainless steel tray, use an airbrush to uniformly spray the surface treatment solution on the surface of the silanized rice husk powder at a flow rate of 0.2mL / min, the spraying amount is controlled at 2.5% of the mass of the silanized rice husk powder, the spraying distance is 20 cm, and the spraying is repeated 3 times (drying interval 10s), after spraying, immediately transfer to a hot air circulation oven at 120°C for 20 min, after cooling, pass through an 80 mesh sieve to remove agglomerated particles, and collect the modified bio-based powder.

[0062] Example 5

[0063] Preparation of modified bio-based powder:

[0064] B1, mixed anhydrous ethanol and silane coupling agent KH-550 according to the volume ratio of 19:1 to prepare a treatment solution, and then dried the rice hull powder in an oven at 105°C for 2h. After completion, the dried rice hull powder was immersed in the treatment solution according to the solid-liquid ratio of 1:10. The system was heated to 60°C and magnetically stirred (speed 300 rpm) for 30 min. During this period, ultrasonic treatment was started every 10 min for 5 min (power 200 W) simultaneously. After completion, the powder was separated by suction filtration and collected. The physical adsorbate was removed by washing with anhydrous ethanol for 3 times. Then, the powder was placed in a vacuum dryer at 80°C for 5h to obtain silanized rice hull powder.

[0065] B2, a tannic acid-water solution with a mass concentration of 0.5wt% was prepared. Then, the pH of the tannic acid-water solution was adjusted to 5.0 using a 0.1 mol / L NaOH solution. After completion, a surface treatment solution was obtained.

[0066] B3, the silanized rice hull powder was evenly sprayed with the surface treatment solution on the surface of the silanized rice hull powder using a spray gun at a flow rate of 0.2 mL / min. The spraying amount was controlled at 5.0% of the mass of the silanized rice hull powder. The spraying distance was 20 cm. The spraying was repeated for 3 times with an interval of 10 s for drying. After completion of the spraying, the silanized rice hull powder was immediately transferred to a hot air circulation oven at 120°C for solidification for 30 min. After cooling, the agglomerated particles were removed by passing through an 80 mesh sieve. The modified bio-based powder was collected.

[0067] Example 6

[0068] Preparation of modified bio-based powder:

[0069] B1, mixed anhydrous ethanol and silane coupling agent KH-550 according to the volume ratio of 19:1 to prepare a treatment solution, and then dried the rice hull powder in an oven at 110°C for 2h. After completion, the dried rice hull powder was immersed in the treatment solution according to the solid-liquid ratio of 1:10. The system was heated to 65°C and magnetically stirred (speed 300 rpm) for 30 min. During this period, ultrasonic treatment was started every 10 min for 5 min (power 200 W) simultaneously. After completion, the powder was separated by suction filtration and collected. The physical adsorbate was removed by washing with anhydrous ethanol for 3 times. Then, the powder was placed in a vacuum dryer at 100°C for 5h to obtain silanized rice hull powder.

[0070] B2, a tannic acid-water solution with a mass concentration of 0.5wt% was prepared. Then, the pH of the tannic acid-water solution was adjusted to 5.2 using a 0.1 mol / L NaOH solution. After completion, a surface treatment solution was obtained.

[0071] B3, spread the silanized rice husk powder on a stainless steel tray, use a spray gun to evenly spray the surface treatment solution on the surface of the silanized rice husk powder at a flow rate of 0.2 mL / min, the spraying amount is controlled at 5.0% of the mass of the silanized rice husk powder, the spraying distance is 20 cm, reciprocating spraying 3 times (interval 10 s drying), after spraying, immediately transfer to a 120°C hot air circulating oven for curing for 30 min, after cooling, remove the agglomerated particles through an 80 mesh sieve, and collect the modified bio-based powder.

[0072] Comparative Example 2

[0073] Comparative Example 2 is a control group of Example 5, compared with Example 5, the tannin acid spraying is cancelled, only the silanization treatment is retained, and other raw materials, raw material amounts, and preparation steps remain consistent with those in Example 5, and finally silanized rice husk powder is obtained.

[0074] Example 7

[0075] A high-bio-based-content shoe sole rubber material and a preparation method thereof

[0076] First, the high-bio-based-content shoe sole rubber material includes the following components by mass:

[0077] 20 parts of natural rubber, 20 parts of modified polyhydroxybutyrate prepared in Example 1, 20 parts of modified bio-based powder prepared in Example 4, 5 parts of biodegradation aid, 6 parts of compatibilizer, 10 parts of reinforcing agent, 2 parts of coupling agent, 2 parts of accelerator, 3 parts of antioxidant, 2 parts of crosslinking agent, 2 parts of wear-resistant reinforcing agent, and 2 parts of processing aid;

[0078] The biodegradation aid is a mixture of polycaprolactone and polybutylene succinate in a mass ratio of 1:1.

[0079] The compatibilizer is a mixture of epoxy soybean oil and maleic anhydride grafted polylactic acid in a mass ratio of 2:1.

[0080] The reinforcing agent is kaolin.

[0081] The coupling agent is KH-550.

[0082] The accelerator is triallyl isocyanurate.

[0083] The antioxidant is antioxidant RD.

[0084] The crosslinking agent is 1,4-bis-tert-butyl peroxyisopropyl benzene.

[0085] The wear-resistant reinforcing agent is a mixture of nanocellulose whiskers and bamboo charcoal powder in a mass ratio of 1:3.

[0086] The processing aid is tributyl citrate.

[0087] Then, the preparation method of the bio-based shoe sole material specifically comprises the following steps:

[0088] S1, each raw material is weighed according to mass fraction, then the natural rubber and the modified polyhydroxybutyrate prepared in example 1 are added into a banbury mixer with a temperature of 120 DEG C and a rotating speed of 50 r / min, and are mixed for 10 min to a molten state, then the modified bio-based powder prepared in example 4 is added into the banbury mixer, and the temperature and the rotating speed are controlled to be unchanged, and the mixture is mixed uniformly for 8 min to obtain a master batch.

[0089] S2, the biodegradation aid, the compatibilizer, the reinforcing agent, the coupling agent, the accelerator, the antioxidant, the crosslinking agent, the wear-resistant reinforcing agent and the processing aid are sequentially added into the banbury mixer containing the master batch in step S1 according to mass fraction, the temperature and the rotating speed are controlled to be unchanged, and the mixture is continuously mixed uniformly for 5 min and then cooled to room temperature to obtain a mixture, the mixture is granulated in a granulator to obtain a sample.

[0090] S3, the sample obtained in step S2 is placed into a vulcanization forming machine, the vulcanization temperature is controlled to be 150 DEG C, and the vulcanization time is 3 h, then the vulcanization is completed, and the vulcanized material is cooled to room temperature and taken out of the vulcanization forming machine to obtain a bio-based shoe sole material.

[0091] Example 8

[0092] A high-bio-based-content shoe sole rubber material and a preparation method thereof:

[0093] Firstly, the high-bio-based-content shoe sole rubber material comprises the following components in mass fraction:

[0094] The natural rubber is 25 parts, the modified polyhydroxybutyrate prepared in example 2 is 27 parts, the modified bio-based powder prepared in example 5 is 28 parts, the biodegradation aid is 7 parts, the compatibilizer is 9 parts, the reinforcing agent is 12 parts, the coupling agent is 2 parts, the accelerator is 4 parts, the antioxidant is 3 parts, the crosslinking agent is 3 parts, the wear-resistant reinforcing agent is 2 parts, and the processing aid is 2 parts.

[0095] The biodegradation aid is a compound of polycaprolactone and polybutylene succinate with a mass ratio of 1:1;

[0096] The compatibilizer is a compound of epoxidized soybean oil and maleic anhydride grafted polylactic acid with a mass ratio of 2:1;

[0097] The reinforcing agent is bentonite;

[0098] The coupling agent is KH-560;

[0099] The accelerator is a compound of triallyl isocyanurate and trimethylolpropane trimethacrylate with a mass ratio of 1:1;

[0100] The anti-aging agent is a mixture of anti-aging agent RD and anti-aging agent 4010NA in a mass ratio of 2:1.

[0101] The crosslinking agent is 1,1'-bis(tert-butyl peroxy)-3,3,5-trimethylcyclohexane.

[0102] The wear-resistant reinforcing agent is a mixture of nanocellulose whiskers and bamboo charcoal powder in a mass ratio of 1:3.

[0103] The processing aid is tributyl citrate.

[0104] Then, the preparation method of the bio-based shoe sole material specifically comprises the following steps:

[0105] S1, the raw materials are weighed according to the mass fraction, then the natural rubber and the modified polyhydroxybutyrate prepared in Example 2 are added into a banbury mixer with a temperature of 130 DEG C and a rotating speed of 50 r / min, and the mixture is banburyed for 15 min to a molten state, then the modified bio-based powder prepared in Example 5 is added into the banbury mixer, and the temperature and the rotating speed are controlled to be unchanged, and the mixture is banburyed for 10 min to be uniformly mixed, to obtain a master batch.

[0106] S2, the biodegradation aid, the compatibilizer, the reinforcing agent, the coupling agent, the accelerator, the anti-aging agent, the crosslinking agent, the wear-resistant reinforcing agent and the processing aid are sequentially added into the banbury mixer containing the master batch in step S1 according to the mass fraction, the temperature and the rotating speed are controlled to be unchanged, and the mixture is continuously banburyed for 10 min and then cooled to room temperature, to obtain a mixture, which is granulated in a granulator to obtain a sample.

[0107] S3, the sample obtained in step S2 is placed into a vulcanization forming machine, the vulcanization temperature is controlled to be 150 DEG C, and the vulcanization time is controlled to be 4 h, then the vulcanization is ended, the vulcanized material is cooled to room temperature, and the vulcanized material is taken out of the vulcanization forming machine, to obtain a bio-based shoe sole material.

[0108] Example 9

[0109] A high-bio-based-content shoe sole rubber material and a preparation method thereof:

[0110] Firstly, the high-bio-based-content shoe sole rubber material comprises the following components in mass fraction:

[0111] The natural rubber is 30 parts, the modified polyhydroxybutyrate prepared in Example 3 is 30 parts, the modified bio-based powder prepared in Example 6 is 30 parts, the biodegradation aid is 8 parts, the compatibilizer is 12 parts, the reinforcing agent is 12 parts, the coupling agent is 8 parts, the accelerator is 4 parts, the anti-aging agent is 3 parts, the crosslinking agent is 4 parts, the wear-resistant reinforcing agent is 2 parts, and the processing aid is 2 parts.

[0112] The biodegradation aid is a mixture of polycaprolactone and polybutylene succinate in a mass ratio of 1:1.

[0113] The compatilizer is compounded from epoxy soybean oil and maleic anhydride grafted polylactic acid at a mass ratio of 2:1;

[0114] The reinforcing agent is white carbon black;

[0115] The coupling agent is KH-570;

[0116] The accelerator is trimethylolpropane trimethacrylate;

[0117] The antioxidant is antioxidant 4010NA;

[0118] The crosslinking agent is 2,5-dimethyl-2,5-bis(tert-butyl peroxy) hexane;

[0119] The wear-resistant reinforcing agent is compounded from nanocellulose whiskers and bamboo charcoal powder at a mass ratio of 1:3;

[0120] The processing aid is glyceryl stearate.

[0121] Then, the preparation method of the bio-based shoe sole material specifically includes the following steps:

[0122] S1, the raw materials are weighed according to the mass fraction, then the natural rubber and the modified polyhydroxybutyrate prepared in Example 3 are added into a temperature of 140℃ mixing machine, the rotating speed is 50r / min, and the mixing is carried out for 15min to the molten state, then the modified bio-based powder prepared in Example 6 is added into the mixing machine, the temperature and the rotating speed are controlled to be unchanged, and the mixing is carried out for 10min to be uniform, and a master batch is obtained.

[0123] S2, the biodegradation aid, the compatilizer, the reinforcing agent, the coupling agent, the accelerator, the antioxidant, the crosslinking agent, the wear-resistant reinforcing agent and the processing aid are sequentially added into the mixing machine containing the master batch in step S1 according to the mass fraction, the temperature and the rotating speed are controlled to be unchanged, the mixing is continuously carried out for 10min, and then the mixture is cooled to room temperature, a mixture is obtained, the mixture is put into a granulator to be granulated, and a sample is obtained.

[0124] S3, the sample obtained in step S2 is put into a vulcanization forming machine, the vulcanization temperature is controlled to be 160℃, the vulcanization time is 4h, after the vulcanization is completed, the vulcanization material is cooled to room temperature, and then the vulcanization material is taken out from the vulcanization forming machine, and a bio-based shoe sole material is obtained.

[0125] Comparative Example 3 (modified polyhydroxybutyrate without wood vinegar)

[0126] Comparative Example 3 is a control group of Example 8, compared with Example 8, the modified polyhydroxybutyrate prepared in Example 2 is replaced by the modified polyhydroxybutyrate prepared in Comparative Example 1, and the other raw materials, the raw material amount and the preparation steps are consistent with those in Example 8, and finally a bio-based shoe sole material is obtained.

[0127] Comparative Example 4 (without spraying tannin acid treatment)

[0128] Comparative Example 4 is a control group of Example 8, compared with Example 8, the raw material modified bio-based powder prepared in Example 5 is replaced by silanized husk powder prepared in Comparative Example 2, and other raw materials, raw material amount, preparation steps remain consistent with Example 8, finally a bio-based sole material is obtained.

[0129] Comparative Example 5 (biodegradation aid single component)

[0130] Comparative Example 5 is a control group of Example 8, compared with Example 8, the raw material biodegradation aid only uses polycaprolactone, and other raw materials, raw material amount, preparation steps remain consistent with Example 8, finally a bio-based sole material is obtained.

[0131] Comparative Example 6 (compatibility agent only uses epoxy soybean oil)

[0132] Comparative Example 6 is a control group of Example 8, compared with Example 8, the raw material compatibility agent only uses epoxy soybean oil, and other raw materials, raw material amount, preparation steps remain consistent with Example 8, finally a bio-based sole material is obtained.

[0133] Comparative Example 7 (unmodified polyhydroxybutyrate matrix)

[0134] Comparative Example 7 is a control group of Example 8, compared with Example 8, the modified polyhydroxybutyrate prepared in Example 2 is replaced by the raw material polyhydroxybutyrate (melt index 8 g / 10 min), and other raw materials, raw material amount, preparation steps remain consistent with Example 8, finally a bio-based sole material is obtained.

[0135] Test Example 1

[0136] The bio-based sole materials prepared in Examples 7-9 and Comparative Examples 3-7 are tested for performance, and the performance testing process is as follows, and the test results are shown in Table 1:

[0137] I. Wet friction coefficient test:

[0138] 1. Test standard: SATRA TM144:2017 "Shoe Anti-slip Performance Test Method".

[0139] 2. Test process:

[0140] (1) Sample preparation: cut the bio-based sole material into 100 mm x 50 mm x 6 mm test pieces;

[0141] (2) Wet treatment: use a micro pump to spray deionized water (0.5 mL / 100 cm 2 );

[0142] (3) Test parameters: test bench inclination angle: 7° (simulated walking slope); contact pressure: 0.5 MPa; sliding speed: 0.3 m / s.

[0143] (4) Data collection: record the ratio of tangential friction force to normal force through the force sensor, which is the wet friction coefficient value.

[0144] II. Abrasion resistance test:

[0145] 1. Test standard: DIN 53516:2017 "Determination of the abrasion resistance of rubber".

[0146] 2. Test process:

[0147] (1) Sample: prepare a cylindrical sample of the bio-based sole material with a diameter of 6 mm and a thickness of 3 mm;

[0148] (2) Test conditions: sandpaper granularity: 60 mesh; load: 10 N; abrasion distance: 40 m; temperature: 23 ± 2°C;

[0149] (3) Result calculation: volume loss = mass difference before and after abrasion / material density.

[0150] III. Tensile strength test:

[0151] 1. Test standard: ASTM D412-2016 "Tensile properties of vulcanized rubber".

[0152] 2. Test process:

[0153] (1) Dumbbell-shaped sample: type 2 sample (thickness 2.0 ± 0.2 mm);

[0154] (2) Tensile speed: 500 mm / min;

[0155] (3) Test parameters: record the breaking strength and elongation at break.

[0156] IV. Hardness test:

[0157] 1. Test standard: ASTM D2240-2021 "Rubber hardness test".

[0158] 2. Test method: use a Shore A hardness tester, test 5 points and take the average value.

[0159] V. Biodegradation rate verification:

[0160] 1. Test standard: ISO 14855-1:2012 "Determination of the biodegradation rate under composting conditions".

[0161] 2. Test points: The bio-based shoe sole material is crushed into 2mm particles and incubated in a compost environment at 58°C and 50% humidity for 90 days. The degradation rate is calculated by the amount of CO2 released.

[0162] Six. Bio-based content determination:

[0163] 1. Measurement standard: ASTM D6866 standard (carbon-14 method) measurement.

[0164] 2. Test process:

[0165] (1) Sample preparation: The bio-based shoe sole material is crushed to 80 mesh;

[0166] (2) Combustion treatment: High-temperature combustion of the sample in a pure oxygen environment releases CO2 gas;

[0167] (3) Carbon-14 detection: Accelerator mass spectrometry is used to determine the carbon-14 isotope content in CO2;

[0168] (4) Bio-based content calculation:

[0169] Bio-based content = [carbon 14 content in sample / carbon 14 content in modern carbon standard] x 100%.

[0170] Table 1 Test results

[0171] Item Example 7 Example 8 Example 9 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Wet friction coefficient 0.68±0.02 0.71±0.02 0.70±0.02 0.58±0.03 0.60±0.03 0.68±0.02 0.64±0.03 0.49±0.04 Wear resistance (mm 3 ) 76±4 72±3 73±4 78±5 105±8 80±4 81±4 87±5 Tensile strength (MPa) 14.7±0.6 15.8±0.5 15.3±0.5 12.1±0.6 14.2±0.5 13.5±0.7 14.1±0.6 15.1±0.5 Elongation at break (%) 340±10 360±10 350±10 310±10 330±10 290±15 320±10 220±10 Hardness (Shore A) 70±1 71±1 70±1 70±1 64±1 70±1 65±1 69±1 Degradation rate (%) 71±2 73±2 71±2 63±2 70±2 58±3 70±2 70±2 Bio-based content (%) 76.5±1.2 78.1±1.1 77.7±1.0 74.4±1.3 75.8±1.2 76.3±1.2 74.2±1.0 77.1±0.9

[0172] Data analysis from Table 1 is as follows:

[0173] I. Data analysis of Examples 7-9:

[0174] (1) Wet friction coefficient (0.68-0.71): All examples meet the EU safety shoe standard (≥0.7), thanks to the synergistic effect of modified polyhydroxybutyrate (wood vinegar liquid enhances interface bonding) and tannin acid treated bio-based powder (improves surface hydrophobicity).

[0175] (2) Wear resistance (72-76mm 3 ): Nanocellulose whiskers and bamboo charcoal powder provide rigid support and reduce wear.

[0176] (3) Tensile strength (14.7-15.8MPa) and elongation at break (340%-360%): The bicontinuous phase structure of modified polyhydroxybutyrate (starch-polyhydroxybutyrate crosslinking) and the compounding of compatibilizers (epoxidized soybean oil + maleic anhydride grafted polylactic acid) optimize the mechanical properties.

[0177] (4) Biodegradation rate (71-73%): The degradation of the polybutylene succinate (PBS) and polycaprolactone (PCL) composite was accelerated by the microbial decomposition.

[0178] II. Data analysis of Comparative Example 3-Comparative Example 7 and Example 8:

[0179] 1. Comparative Example 3 (unmodified polyhydroxybutyrate with vinegar):

[0180] (1) Wet friction coefficient decreased (0.58 vs 0.71): Phenolic substances in vinegar form hydrogen bonds with starch / polyhydroxybutyrate, enhancing interfacial bonding, and the removal of the interface defects leads to reduced slip resistance.

[0181] (2) Biodegradation rate decreased (63% vs 73%): Organic acids in vinegar may promote microbial activity, and their absence slows down the degradation rate.

[0182] 2. Comparative Example 4 (untreated bio-based powder with tannic acid):

[0183] (1) Wet friction coefficient decreased (0.60 vs 0.71): The tannic acid coating forms a hydrogen bond network with the rubber matrix through the polyphenol hydroxyl group, improving surface hydrophobicity, and the water film is difficult to remove after removal.

[0184] (2) Abrasion resistance deteriorated (105 mm 3 vs 72 mm 3 ): Tannic acid enhances the bonding force between the powder and the matrix, and untreated powder is prone to fall off, leading to increased wear.

[0185] 3. Comparative Example 5 (single biodegradation agent polycaprolactone):

[0186] Biodegradation rate decreased (58% vs 73%): The complementary degradation mechanism (rapid hydrolysis of PBS and slow enzymatic degradation of PCL) can be formed by the combination of PBS and PCL, and the single PCL has low degradation efficiency.

[0187] 4. Comparative Example 6 (only with epoxy soybean oil compatibilizer):

[0188] (1) Wet friction coefficient decreased (0.64 vs 0.71): Maleic anhydride grafted polylactic acid can improve the compatibility of polyhydroxybutyrate and natural rubber, and single epoxy soybean oil cannot effectively reduce the interfacial tension.

[0189] (2) Hardness decreased (65 vs 71): Insufficient compatibility leads to increased porosity in the material.

[0190] 5. Comparative Example 7 (unmodified polyhydroxybutyrate matrix):

[0191] (1) Significant decrease in wet friction coefficient (0.49 vs 0.71): Poor compatibility of unmodified polyhydroxybutyrate with natural rubber, phase separation leading to insufficient surface roughness.

[0192] (2) Abrupt decrease in elongation at break (220% vs 360%): High crystallinity of polyhydroxybutyrate, no bi-continuous phase with starch, increased brittleness.

[0193] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; for example, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It must be noted that as used herein, the singular forms "a", "an" and "the" include plural references unless the context clearly dictates otherwise. As such, the terms "comprise", "comprises" and "comprising" or any variation thereof, will be understood to enable a process, method, article, or apparatus that "comprises", "comprises" and "comprising" a list of elements without precluding other elements not explicitly listed.

[0194] While embodiments of the application have been shown and described, it is to be understood that various further modifications and changes can be made thereto without departing from the spirit and scope of the present application, which is defined by the appended claims and their equivalents.

Claims

1. A high-bio-based content shoe sole rubber material, characterized by, The components include the following quality parts: natural rubber 20-30 parts, modified polyhydroxybutyrate 20-30 parts, modified bio-based powder 20-30 parts, biodegradation aid 5-8 parts, compatibility agent 6-12 parts, reinforcing agent 10-12 parts, coupling agent 2-8 parts, accelerator 2-4 parts, antioxidant 3 parts, crosslinking agent 2-4 parts, wear-resistant reinforcing agent 2 parts, processing aid 2 parts; The modified polyhydroxybutyrate is prepared by the following steps: A1, corn starch is mixed with plasticizer glycerol according to a mass ratio of 10:3, extruded, granulated, cooled, and cut into particles at 120-130°C to obtain thermoplastic starch masterbatch; A2, polyhydroxybutyrate and pyroligneous liquid are mixed, and mixed at 155-160°C for 5-10 min, then the thermoplastic starch masterbatch is added, and the temperature is raised to 165-170°C for mixing for 8-10 min, then the temperature is lowered to 130-140°C, and dicumyl peroxide is added, and mixing is continued for 3-5 min, and then the system is cooled to room temperature to obtain modified polyhydroxybutyrate; The modified bio-based powder is prepared by the following steps: B1, anhydrous ethanol and silane coupling agent KH-550 are mixed according to a volume ratio of 19:1 to obtain a treatment solution, and then the husk powder is dried in an oven at 105-110°C for 2 h, then the dried husk powder is immersed in the treatment solution according to a solid-liquid ratio of 1:10, the system is heated to 60-65°C, and then constant temperature magnetic stirring is performed for 30 min, during which ultrasonic treatment is performed for 5 min every 10 min, then the powder is collected by filtration, washed with anhydrous ethanol for 3 times to remove physical adsorbents, and then placed in a vacuum dryer at 80-100°C for 4-5 h to obtain silanized husk powder; B2, a tannic acid-water solution with a mass concentration of 0.5wt% is prepared, and then the pH of the tannic acid-water solution is adjusted to 5.0-5.2 by using a 0.1mol / L NaOH solution to obtain a surface treatment solution; B3, the surface treatment solution is sprayed on the surface of the silanized husk powder at a flow rate of 0.2mL / min by using an airbrush, and the spraying amount is controlled to be 2.5%-5.0% of the mass of the silanized husk powder, then hot air curing and cooling are performed, and then the product is sieved through an 80 mesh sieve to obtain modified bio-based powder; The biodegradation aid is a compound of polycaprolactone and polybutylene succinate according to a mass ratio of 1:1; and the compatibility agent is a compound of epoxidized soybean oil and maleic anhydride grafted polylactic acid according to a mass ratio of 2:1; The wear-resistant reinforcing agent is a compound of nanocellulose whiskers and bamboo charcoal powder according to a mass ratio of 1:

3. The mass ratio of the polyhydroxybutyrate, pyroligneous liquid, thermoplastic starch masterbatch, and dicumyl peroxide in A2 is 28-30:3-5:15-20:0.5-1.

0.

2. A high bio-based content shoe sole rubber material according to claim 1, characterized in that, The corn starch and glycerol in A1 are mixed according to a mass ratio of 10:

3.

3. A high bio-based content shoe sole rubber material according to claim 1, characterized in that, The reinforcing agent is one of kaolin, bentonite, and white carbon black; the coupling agent is one of KH-550, KH-560, and KH-570; and the accelerator is a compound of triallyl isocyanurate and trimethylolpropane trimethacrylate according to a mass ratio of 1:

1.

4. The high-biocontent shoe sole rubber material of claim 1, wherein, The anti-aging agent is one or two of anti-aging agent RD and anti-aging agent 4010NA compounded in a mass ratio of 2:1; the crosslinking agent is one of 1,4-bis-tert-butyl peroxyisopropyl benzene, 1,1'-bis(tert-butyl peroxy)-3,3,5-trimethylcyclohexane, and 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane.

5. The high-biocontent shoe sole rubber material of claim 1, wherein, The processing aid is one of tributyl citrate and glyceryl stearate.

6. A process for the preparation of a high bio-based content shoe sole rubber material according to any one of claims 1 to 5, characterized in that, The method comprises the following steps: S1, according to the mass fraction, each raw material is weighed, the natural rubber and the modified polyhydroxybutyrate are added into a temperature of 120-140℃ of an internal mixer, the rotating speed is 50r / min, and the internal mixing is performed for 10-15min, then the modified bio-based powder is added into the internal mixer, the temperature and the rotating speed are controlled to be unchanged, and the internal mixing is performed for 8-10min to obtain a master batch; S2, the biodegradation aid, the compatibilizer, the reinforcing agent, the coupling agent, the accelerator, the anti-aging agent, the crosslinking agent, the wear-resistant reinforcing agent, and the processing aid are sequentially added into the internal mixer containing the master batch in step S1 according to the mass fraction, the temperature and the rotating speed are controlled to be unchanged, the internal mixing is continuously performed for 5-10min, and then the mixture is cooled to room temperature to obtain a mixed material, the mixed material is put into a granulator to be granulated to obtain a sample; S3, the sample obtained in step S2 is put into a vulcanization forming machine, the vulcanization temperature is controlled to be 150-160℃, the vulcanization time is 3-4h, after the vulcanization is finished, the vulcanization material is cooled to room temperature, and then the vulcanization material is taken out from the vulcanization forming machine to obtain a bio-based sole material.