Preparation method of durability-enhanced modified rubber and application of durability-enhanced modified rubber in sole material

Abstract

The invention relates to the technical field of modified rubber, in particular to a preparation method of durability-enhanced modified rubber and application of the durability-enhanced modified rubber in a sole material. The method comprises the following steps: 1, preparing raw materials; step 2, plastifying; step 3, mixing the master batch; 4, mixing the final mixed rubber; step 5, vulcanization molding; according to the preparation method of the durability-enhanced modified rubber and the application of the durability-enhanced modified rubber in a sole material, the modified rubber can improve the comprehensive performance of a sole, and the Brazilian trefoil rubber endows the sole with good elasticity; according to the present invention, the rigidity and the wear resistance of the sole are enhanced by the ancient Titan wave glue, the sole adapts to various complex pavements, the plasticizer pine tar softens the rubber, the secondary combination of the lignin fiber and the vulcanized rubber network can further increase the mechanical property of the rubber, and the vulcanizing efficiency is improved by adding the active agent; and comprehensively, the quality and durability of the sole are improved, so that the practicability of the modified rubber applied to the sole material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of modified rubber, in particular to a method for preparing modified rubber with enhanced durability and application of the modified rubber in shoe sole materials. Background Art

[0002] In the application field of rubber materials, the wear and tear of rubber and the friction coefficient of rubber are key indicators for judging the use of rubber materials in high friction environments. At present, adding nanofillers to rubber materials is a relatively effective means to improve performance. Nanofillers can theoretically effectively enhance the wear resistance and friction coefficient of rubber due to their small size effect and large specific surface area. However, this method has significant limitations. Nanofillers are very easy to agglomerate in the rubber matrix and are difficult to disperse evenly, which greatly weakens their reinforcement effect and cannot fully play the role of improving rubber performance. In addition, the production and processing costs of nanofillers are high, which greatly increases the production cost of rubber products and reduces market competitiveness. At the same time, some nanofillers may be biologically toxic and pose a potential threat to the environment and human health during production, use and waste disposal. In addition, existing methods often only focus on improving one of the wear resistance or friction coefficient, ignoring the synergistic improvement of other rubber properties, resulting in the difficulty of sole materials to meet the diverse actual needs.

[0003] Existing modified rubbers have some shortcomings for sole materials. For example, in terms of performance, most modified rubbers are difficult to balance elasticity, rigidity and wear resistance. Although the wear resistance of some soles has been improved, the elasticity is insufficient and the comfort when walking is poor. The wear resistance and rigidity of soles that focus on elasticity are difficult to adapt to the requirements of complex road surfaces and long-term use. In terms of anti-aging performance, existing modified rubbers perform poorly. Under the influence of environmental factors such as ultraviolet rays, oxygen, and ozone, aging phenomena such as hardening, cracking, and fading easily occur, which greatly shortens the service life of the soles, thereby reducing the practicality of modified rubber in sole materials.

[0004] In view of this, there is an urgent need for a preparation method of a modified rubber with enhanced durability and its application in sole materials. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing a modified rubber with enhanced durability and application of the modified rubber in a shoe sole material, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, on the one hand, the present invention provides a method for preparing a modified rubber with enhanced durability, comprising the following steps:

[0007] S1. Raw material preparation: Hevea brasiliensis, gutta-percha, plasticizer, lignin fiber, natural rubber vulcanizer, activator and natural antioxidant;

[0008] S2, plastication: put the Brazilian hevea rubber into an open mill for plastication. During plastication in the open mill, the roller temperature, roller distance and thickness are adjusted to improve the plasticity of the rubber, so as to facilitate the uniform dispersion of other compounding ingredients during subsequent mixing;

[0009] S3, masterbatch mixing: the plasticized Brazilian hevea rubber is placed in an open mixer, and the roller temperature and roller distance are adjusted, and then the plasticizer, lignin fiber and activator are added in sequence for mixing to make the components evenly dispersed. After the mixing is completed, the masterbatch is cooled and set aside;

[0010] S4, final rubber mixing: the cooled masterbatch is put back into the open mill, gutta-percha is added, the open mill is mixed, and the roller temperature, roller distance and mixing time are adjusted to make the gutta-percha and the masterbatch fully mixed, then, the natural rubber vulcanizer and the natural antioxidant are added to continue mixing, and the roller temperature, roller distance and mixing time are adjusted. After the mixing is completed, the final rubber is unrolled and cooled to room temperature;

[0011] S5, vulcanization molding: the cooled final rubber is weighed according to the weight requirements of the sole mold, and is placed in a preheated vulcanization mold for vulcanization, and the temperature, pressure and vulcanization time of the vulcanization mold are set. After the vulcanization is completed, the sole product is taken out and demolded to obtain a modified rubber sole with enhanced durability.

[0012] As a further improvement of the technical solution, the S1 includes the following raw materials in amounts:

[0013] The dosage of Brazilian hevea is 50-60 parts;

[0014] The amount of gutta-percha used is 12-20 parts;

[0015] The amount of plasticizer is 6-10 parts;

[0016] The amount of lignin fiber is 4-8 parts;

[0017] The dosage of natural rubber vulcanizer is 1.2-3 parts;

[0018] The dosage of the active agent is 4-7 parts;

[0019] The dosage of natural antioxidant is 1.2-3 parts.

[0020] As a further improvement of the technical solution, in S1, the plasticizer is pine tar; the natural rubber vulcanizer is sulfur; the activator is zinc oxide and stearic acid, wherein the amount of zinc oxide is 3-5 parts and the amount of stearic acid is 1-2 parts; and the natural antioxidant is rosemary extract.

[0021] As a further improvement of the technical solution, in S2, the roller temperature is adjusted to 50°C-60°C, the roller distance is adjusted to 1mm-2mm, and the thin pass is controlled to 5-8 times.

[0022] As a further improvement of the technical solution, in S3, the roller temperature is adjusted to 60°C-70°C, and the roller distance is adjusted to 3mm-5mm.

[0023] As a further improvement of the technical solution, in S3, the mixing time of the plasticizer, lignin fiber and active agent is 12 minutes to 15 minutes.

[0024] As a further improvement of the technical solution, in S4, gutta-percha is added, the roller temperature is adjusted to 60°C-70°C, the roller distance is adjusted to 3mm-5mm, and the mixing time is 5min-8min.

[0025] As a further improvement of the technical solution, in S4, natural rubber vulcanizer and natural antioxidant are added to continue mixing, the roller temperature is adjusted to 40°C-50°C, the roller distance is adjusted to 6mm-8mm, and the mixing time is 5min-8min.

[0026] As a further improvement of the technical solution, in S5, the temperature of the vulcanization mold is 150° C.-160° C., the pressure is 10 MPa-15 MPa, and the vulcanization time is 15 min-30 min.

[0027] On the other hand, the present invention provides a use of a modified rubber produced by any one of the above methods for preparing a modified rubber with enhanced durability in a sole material.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. A preparation method of the modified rubber with enhanced durability and its application in sole materials. The modified rubber is applied to sole materials to improve the comprehensive performance of the sole. The Brazilian hevea rubber gives the sole good elasticity, making walking easier and more comfortable; the gutta-percha enhances the rigidity and wear resistance of the sole and adapts to various complex road surfaces. The plasticizer pine tar makes the rubber soft and improves the wearing experience. The secondary combination of lignin fiber and vulcanized rubber network can further increase the mechanical properties of the rubber and improve the wear resistance and tear resistance of the sole. The activator improves the vulcanization efficiency and makes the sole performance more stable. The natural antioxidant inhibits aging and prolongs the service life. Overall, the quality and durability of the sole are improved, thereby improving the practicality of the modified rubber applied to sole materials.

[0030] 2. The preparation method of the modified rubber with enhanced durability and its application in the sole material: the modified rubber uses natural ingredients as raw materials, such as Brazilian hevea, pine tar and rosemary extract, which reduces the use of environmentally harmful chemicals and reduces pollution to the environment. In terms of economy, the amount of raw materials and process parameters are controlled, the production efficiency is improved, and the production cost is reduced. Moreover, the soles with enhanced durability reduce the frequency of replacement by consumers and reduce the cost of use. In addition, the preparation process of each step, such as the adjustment of temperature, roller distance, etc. during the plasticating and mixing processes, improves the stability of product quality, thereby increasing the service life of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The flowchart of the method for preparing the modified rubber with enhanced durability of the present invention is as follows;

[0032] Figure 2 It is a histogram of wear amount of the present invention;

[0033] Figure 3 is a histogram of tear strength of the present invention;

[0034] Figure 4 It is a bar graph of compression set rate of the present invention;

[0035] Figure 5 The Shore A hardness bar graph of the present invention;

[0036] Figure 6 is a bar graph of the content of volatile organic matter of the present invention;

[0037] Figure 7 This is a bar graph of lead content in the present invention. DETAILED DESCRIPTION

[0038] The following will be combined with the accompanying drawings in the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0039] according to Figure 1 As shown, an embodiment of the present invention provides a method for preparing a modified rubber with enhanced durability, comprising the following steps:

[0040] Step 1: Raw material preparation: Hevea brasiliensis, gutta-percha, plasticizer, lignin fiber, natural rubber vulcanizer, activator and natural antioxidant; including the following raw materials in the following amounts:

[0041] The amount of Brazilian hevea rubber is 50-60 parts (parts by mass). Brazilian hevea rubber is the main source of natural rubber, has good elasticity and tensile strength, and provides basic elastic properties for the sole;

[0042] The amount of gutta-percha used is 12-20 parts by mass. Gutta-percha is hard and elastic at room temperature. When mixed with Brazilian hevea rubber, it can improve the rigidity and wear resistance of the rubber and enhance the durability of the sole.

[0043] The amount of plasticizer used is 6-10 parts (parts by mass). The plasticizer is pine tar, which can soften rubber, improve its flexibility and processing performance, and make the sole more comfortable to wear;

[0044] The amount of lignin fiber is 4-8 parts (mass parts), and lignin fiber can enhance the mechanical properties of rubber, improve the wear resistance of the sole, and further improve durability;

[0045] The amount of natural rubber vulcanizer used is 1.2-3 parts (parts by mass). The natural rubber vulcanizer uses sulfur, which is used to vulcanize rubber to form a cross-linked structure and improve the strength, hardness and wear resistance of the rubber.

[0046] The amount of the active agent is 4-7 parts (mass parts), and the active agent is zinc oxide and stearic acid. The zinc oxide and stearic acid constitute an active agent system to promote the vulcanization reaction, improve the vulcanization efficiency and the performance of the vulcanized rubber, wherein the amount of zinc oxide is 3-5 parts (mass parts), and the amount of stearic acid is 1-2 parts (mass parts);

[0047] The dosage of the natural antioxidant is 1.2-3 parts (by mass), and the natural antioxidant adopts rosemary extract, which can effectively inhibit the oxidation aging of rubber and prolong the service life of the sole;

[0048] Step 2, plastication: put the Brazilian hevea rubber into an open mill for plastication. When plasticating in the open mill, adjust the roller temperature, roller distance and thin pass. The roller temperature is adjusted to 50°C-60°C, the roller distance is adjusted to 1mm-2mm, and the thin pass is controlled to 5-8 times (thin pass refers to the operation of removing the extruded thin film from the roller, re-inserting it between the rollers, and calendering it into a thin film again), so that the plasticity of the rubber is improved, which is convenient for the uniform dispersion of other compounding ingredients during subsequent mixing;

[0049] Step 3, masterbatch mixing: Place the plasticized Brazilian hevea rubber on an open mill, and adjust the roller temperature and roller distance, the roller temperature is adjusted to 60°C-70°C, the roller distance is adjusted to 3mm-5mm, and then add plasticizer, lignin fiber and activator in turn for mixing. The plasticizer, lignin fiber and activator are mixed for 12min-15min to make the components evenly dispersed. After mixing, cool the masterbatch off and set aside;

[0050] Step 4, final rubber mixing: the cooled masterbatch is put back into the open mill, gutta-percha is added, the open mill is mixed, and the roller temperature, roller distance and mixing time are adjusted. The roller temperature is adjusted to 60°C-70°C, the roller distance is adjusted to 3mm-5mm, and the mixing time is 5min-8min, so that the gutta-percha and the masterbatch are fully mixed and uniform. After that, natural rubber vulcanizer and natural antioxidant are added to continue mixing, and the roller temperature, roller distance and mixing time are adjusted. The roller temperature is adjusted to 40°C-50°C to prevent premature reaction of sulfur, the roller distance is adjusted to 6mm-8mm, and the mixing time is 5min-8min. After the mixing is completed, the final rubber is unrolled and cooled to room temperature (room temperature is 20°C-30°C);

[0051] Step 5, vulcanization molding: weigh and cut the cooled final rubber according to the weight requirements of the sole mold (for example, for the sole mold of jogging shoes, the weight of the cooled final rubber is 180g-220g; for the production of basketball shoe sole molds, considering the intensity of basketball sports and the high requirements for sole support and impact resistance, the cooled final rubber weighs 220g-280g; for the sole mold of flat casual shoes, the cooled final rubber is 120g-160g, so that the vulcanized sole is light and comfortable. , fit for daily walking scenes), put it into the preheated vulcanization mold for vulcanization, and set the temperature, pressure and vulcanization time of the vulcanization mold. The temperature of the vulcanization mold is 150℃-160℃, the pressure is 10MPa-15MPa, and the vulcanization time is 15min-30min. During this period, the rubber molecules undergo cross-linking reaction under the action of sulfur to form a three-dimensional network structure to obtain the required physical and mechanical properties. After the vulcanization is completed, take out the sole product and demold it to obtain a modified rubber sole with enhanced durability.

[0052] In the invention, firstly, by adopting and controlling the dosage of various raw materials such as Brazilian hevea rubber and gutta-percha, the various components are fully integrated through the plasticizing and mixing process, which can not only give full play to the raw material characteristics such as the high elasticity of Brazilian hevea rubber and the wear resistance of gutta-percha, but also improve the basic performance of the sole. At the same time, the reasonable addition and use of plasticizers, activators, etc. increase the processing performance and vulcanization effect of the rubber. For example, pine tar softens the rubber to make the sole more comfortable to wear; zinc oxide and stearic acid promote the vulcanization reaction and improve the vulcanization efficiency. In addition, lignin fiber enhances the mechanical properties of rubber, and rosemary extract inhibits the oxidation and aging of rubber, which can also effectively improve the wear resistance and service life of the sole, thereby preparing a modified rubber sole with enhanced durability.

[0053] In the preparation of the modified rubber, the lignin fiber and the rubber network formed by the sulfur-vulcanized Hevea brasiliensis and gutta-percha can be combined for the second time. The reaction mechanism is as follows: sulfur causes the molecular chains of Hevea brasiliensis and gutta-percha to form sulfur-containing cross-links, forming a three-dimensional network structure, in which some of the sulfur-containing cross-links have certain polarity and activity; under the high temperature and high pressure conditions of vulcanization molding, the lone pair of electrons on the oxygen atom of the hydroxyl group contained in the lignin fiber will attack the partially positively charged sulfur atom on the sulfur-containing cross-link in the rubber network, and a nucleophilic substitution reaction will occur, so that the lignin fiber and the rubber network are chemically bonded to strengthen the overall structure. The simplified reaction formula is: the disulfide bond RSSR in the rubber network is first polarized to form RS δ+ -S δ- -R, then react with lignin fiber L-OH to form RS δ+ -S δ- -R+L-OH→RS-L+RS-OH (R represents the rubber molecular chain segment, L-OH represents the lignin fiber).

[0054] Modified rubber is applied to sole materials to improve the overall performance of the sole. Brazilian hevea rubber gives the sole good elasticity, making walking easier and more comfortable. Gutta-percha enhances the rigidity and wear resistance of the sole and adapts to various complex road surfaces. The plasticizer pine tar makes the rubber soft and improves the wearing experience. The secondary combination of lignin fiber and vulcanized rubber network can further increase the mechanical properties of the rubber and improve the wear resistance and tear strength of the sole. The activator improves the vulcanization efficiency and makes the sole performance more stable. Natural antioxidants inhibit aging and extend the service life. Overall, the quality and durability of the sole are improved, thereby improving the practicality of modified rubber in sole materials.

[0055] Modified rubber uses natural ingredients as raw materials, such as Brazilian hevea, pine tar and rosemary extract, which reduces the use of environmentally harmful chemicals and reduces environmental pollution. In terms of economy, it controls the amount of raw materials and process parameters, improves production efficiency and reduces production costs. Moreover, the durability of the soles is enhanced, which reduces the frequency of consumers' replacement and reduces the cost of use. In addition, the preparation process of each step, such as the adjustment of temperature, roller distance, etc. during the plasticating and mixing process, improves the stability of product quality, thereby increasing the service life of the product.

[0056] According to different raw material dosages, the modified rubber provided by the present invention is further described through the following specific examples.

[0057] Example 1

[0058] Raw material dosage: 60 parts of Hevea brasiliensis, 16 parts of gutta-percha, 6 parts of pine tar, 4 parts of lignin fiber, 2 parts of sulfur, 3 parts of zinc oxide, 1 part of stearic acid, 1.2 parts of rosemary extract;

[0059] Preparation process:

[0060] Plastication: Put 50 parts of Brazilian hevea rubber into the open mill, adjust the roller temperature to 50℃, the roller distance to 1mm, and perform 5 thin passes to improve the plasticity of the rubber;

[0061] Masterbatch mixing: put the plasticized rubber on an open mixer, set the roller temperature at 60°C and the roller distance at 3mm, add 6 parts of pine tar, 4 parts of lignin fiber, 3 parts of zinc oxide and 1 part of stearic acid in sequence, mix for 12 minutes, and cool down after the mixing is completed;

[0062] Final rubber mixing: put the cooled masterbatch back into the open mixer, add 12 parts of gutta-percha, set the roller temperature to 60°C, the roller distance to 3mm, and mix for 5 minutes; then add 1.2 parts of sulfur and 1.2 parts of rosemary extract, adjust the roller temperature to 40°C, the roller distance to 6mm, mix for 5 minutes, and cool the lower sheet to room temperature;

[0063] Vulcanization molding: For the sole mold of jogging shoes, weigh 180g of the cooled final rubber and put it into the preheated vulcanization mold, vulcanize it at a temperature of 150℃ and a pressure of 10MPa for 15min, and demold it to obtain the sole.

[0064] Example 2

[0065] Raw material dosage: 55 parts of Brazilian hevea rubber, 12 parts of gutta-percha, 10 parts of pine tar, 6 parts of lignin fiber, 1.2 parts of sulfur, 4 parts of zinc oxide, 1.5 parts of stearic acid, 3 parts of rosemary extract;

[0066] Preparation process:

[0067] Plastication: Put the Brazilian hevea rubber into the open mill, the roller temperature is 55℃, the roller distance is 1.5mm, and the thin pass is 6 times;

[0068] Masterbatch mixing: roller temperature 65℃, roller distance 4mm, add pine tar, lignin fiber, zinc oxide and stearic acid, mix for 13min, and cool down;

[0069] Final mixing: add gutta-percha, roll temperature 65°C, roll distance 4mm, mix for 6min; then add sulfur and rosemary extract, roll temperature 45°C, roll distance 7mm, mix for 6min, and cool the sheet down;

[0070] Vulcanization molding: For the basketball shoe sole mold, weigh 250g of the final rubber, vulcanize at 155℃ and 12MPa for 20min, and demold.

[0071] Example 3

[0072] Raw material dosage: 50 parts of Hevea brasiliensis, 20 parts of gutta-percha, 8 parts of pine tar, 8 parts of lignin fiber, 3 parts of sulfur, 5 parts of zinc oxide, 2 parts of stearic acid, and 2 parts of rosemary extract;

[0073] Preparation process

[0074] Plastication: Brazilian hevea rubber is in an open mill, with a roller temperature of 60°C, a roller distance of 2mm, and 8 passes;

[0075] Masterbatch mixing: roller temperature 70℃, roller distance 5mm, add corresponding raw materials and mix for 15min, then cool down;

[0076] Final mixing: add gutta-percha, roll temperature 70°C, roll distance 5mm, mix for 8min; then add sulfur and rosemary extract, roll temperature 50°C, roll distance 8mm, mix for 8min, and cool the sheet down;

[0077] Vulcanization molding: For the sole mold of flat casual shoes, weigh 160g of final rubber, vulcanize at 160℃ and 15MPa for 30min, and demould.

[0078] Table 1 Amount of raw materials used in Examples 1-3

[0079] Example 1 Example 2 Example 3 Brazilian Hevea Rubber (unit) 60 55 50 Gutta-percha (pack) 16 12 20 Pine tar (part) 6 10 8 Lignin fiber (parts) 4 6 8 Sulfur (parts) 2 1.2 3 Zinc oxide (parts) 3 4 5 Stearic acid (parts) 1 1.5 2 Rosemary Extract (part) 1.2 3 2

[0080] In order to verify that the modified rubber prepared in the embodiment of the present invention has good durability and comprehensive performance, the modified rubber provided in the embodiment of the present invention is described through the following test examples.

[0081] Test example

[0082] The purpose of this test group is to explore the influence of different component ratios on the modified rubber and to detect the durability, comfort and environmental protection of the modified rubber of the present invention.

[0083] Test objectives: Test group A, test group B and test group C respectively use the component ratios of the modified rubber provided in Examples 1-3; the control examples use control group A, control group B and control group C, wherein:

[0084] Control group A

[0085] Materials and methods: Traditional styrene-butadiene rubber was used as the main material, and conventional chemical synthetic plasticizers (dioctyl phthalate), vulcanizers (mixture of accelerator TMTD and sulfur), and antioxidants (anti-aging agent D) were added. During the preparation, the styrene-butadiene rubber was plasticized on an open mill, and then the plasticizer, vulcanizer, antioxidant, etc. were added in sequence for mixing. After mixing evenly, the sole was vulcanized at 140°C and 8MPa for 25 minutes to form the sole;

[0086] Control group B

[0087] Materials and methods: Butadiene rubber was used, nano-calcium carbonate was added as reinforcing filler, chemically synthesized antioxidant RD and accelerator CZ were added. Butadiene rubber was first plasticized, then nano-calcium carbonate, antioxidant and accelerator were added and mixed, and then vulcanized at 145℃ and 10MPa for 22min to obtain the sole.

[0088] Control group C

[0089] Raw material dosage: 50 parts of ordinary styrene-butadiene rubber, 12 parts of natural rubber, 6 parts of pine tar, 1.2 parts of sulfur, 3 parts of zinc oxide, 1 part of stearic acid, 1.2 parts of rosemary extract;

[0090] Preparation process:

[0091] Plastication: Put 50 parts of ordinary styrene-butadiene rubber into an open mill, adjust the roller temperature to 50°C, the roller distance to 1mm, and perform 5 thin-pass operations to improve the plasticity of the rubber;

[0092] Masterbatch mixing: put the plasticized styrene-butadiene rubber on an open mixer, adjust the roller temperature to 60°C, the roller distance to 3mm, add 6 parts of pine tar, 3 parts of zinc oxide and 1 part of stearic acid in turn for mixing, the mixing time is 12 minutes, so that the components are evenly dispersed. After the mixing is completed, cool the masterbatch off and set aside;

[0093] Final rubber mixing: put the cooled masterbatch back into the open mixer, add 12 parts of natural rubber, set the roller temperature to 60°C, the roller distance to 3mm, mix for 5 minutes, make the natural rubber and masterbatch fully mixed, then add 1.2 parts of sulfur and 1.2 parts of rosemary extract and continue mixing, adjust the roller temperature to 40°C, the roller distance to 6mm, and mix for 5 minutes. After mixing, remove the final rubber from the sheet and cool to room temperature;

[0094] Vulcanization molding: For the sole mold of jogging shoes, weigh 180g of the cooled final rubber and put it into the preheated vulcanization mold. The vulcanization mold temperature is 150℃ and the pressure is 10MPa. After vulcanization for 15 minutes, take out the sole product and demould it.

[0095] Test method: The durability, comfort and environmental protection of the modified rubber according to the present invention are tested respectively. The specific test methods are as follows:

[0096] Durability test method:

[0097] The durability is tested by Akron abrasion test and tear strength test. In Akron abrasion test, the sole samples of each test group and control group are installed on the wear machine, the grinding wheel speed is set to 260r / min, the load is 2.67N, and the stroke is 1.61km. After the test, according to the formula Calculate the wear amount W, where m 1 is the mass of the sample before the test, m 2is the mass of the sample after the test, L is the distance the sample travels, the smaller the wear amount, the better the wear resistance; the tear strength test uses a right-angle tearing sample and is tested on an electronic tensile testing machine at a tensile speed of 500mm / min. The maximum force F during tearing is recorded. The larger the value, the higher the tear strength and the better the durability.

[0098] Comfort test method:

[0099] The comfort is evaluated by compression-rebound test and hardness test. In the compression-rebound test, the sole sample is compressed at a certain pressure (2MPa) at a specified temperature (23°C) for 30 minutes and then unloaded. The thickness change is measured after 30 minutes. According to the formula Calculate the compression set R, where h 0 is the initial thickness, h 1 It is the thickness after unloading. The lower the compression permanent deformation rate, the better the elastic recovery and the higher the comfort. At the same time, the hardness H of the sole is measured using a Shore A hardness tester. The lower the hardness value, the softer the sole and the more comfortable it is to wear.

[0100] Environmental testing methods:

[0101] Thermogravimetric analysis (TGA) and inductively coupled plasma mass spectrometry (ICP-MS) were used to detect the volatile organic matter content and heavy metal content, respectively. During the thermogravimetric analysis, an appropriate amount of sole material was taken and heated from room temperature to 800°C at a heating rate of 10°C / min in a nitrogen atmosphere, and the mass loss was recorded to calculate the volatile organic matter content C. org , assuming the initial mass is m total , the remaining mass after thermogravimetric analysis is m residue ,but The lower the value, the better the environmental protection. ICP-MS is used to detect the content of heavy metals (such as lead, cadmium, etc.) in the soles. Taking lead as an example, the mass of lead detected is m Pb , the mass of the sole is m sample , then the lead content The lower the heavy metal content, the better the environmental protection.

[0102] Specific detection indicators are shown in Table 2.

[0103] Table 2 Test indicators of each sample

[0104]

[0105] according to Figure 2-Figure 7 As shown in Table 2, the summary of the above comparative data is as follows:

[0106] 1. Durability

[0107] Abrasion loss: The abrasion loss of test groups A, B, and C is 0.12g / cm2 , 0.10g / cm 2 , 0.08g / cm 2 , much lower than the 0.18g / cm of control group A 2 , control group B 0.15g / cm 2 and control group C of 0.15 g / cm 2 The invention mainly adopts Brazilian hevea rubber to provide elasticity, gutta-percha to enhance rigidity, and the lignin fiber and the vulcanized rubber network are combined for a secondary strengthening structure, so that the sole wears less under the same friction conditions, highlighting the excellent wear resistance of the modified rubber and showing good durability;

[0108] Tear strength: The tear strengths of test groups A, B, and C are 350N, 380N, and 400N, respectively, which are significantly higher than 280N of control group A, 260N of control group B, and 300N of control group C. This is mainly because the mixing of Brazilian hevea rubber and gutta-percha, coupled with the lignin fiber enhancing the mechanical properties, together improve the ability of the rubber to resist tearing by external forces, thereby improving the durability of the modified rubber of the present invention.

[0109] 2. Comfort

[0110] Compression permanent deformation rate: The compression permanent deformation rates of test groups A, B and C were 15%, 13% and 12% respectively, which were lower than 20% of control group A, 22% of control group B and 18% of control group C. This is mainly because the modified rubber of the present invention has good elastic recovery performance after being compressed, which can provide a comfortable foot feeling for the wearer. The elasticity of Brazilian hevea rubber and the softening effect of pine tar can effectively buffer the pressure and rebound quickly when walking.

[0111] Shore A hardness: the Shore A hardnesses of the test groups A, B and C are 55, 52 and 50, respectively, which are lower than 60 of the control group A, 62 of the control group B and 58 of the control group C, indicating that the modified rubber sole of the present invention is softer, and pine tar oil as a plasticizer softens the rubber, thereby improving the flexibility of the sole and enhancing the wearing comfort.

[0112] 3. Environmental protection

[0113] Content of volatile organic matter: the contents of volatile organic matter of test groups A, B and C were 0.9%, 0.6% and 0.5%, respectively, which were significantly lower than 1.5% of control group A, 1.3% of control group B and 1.0% of control group C. This is mainly because the present invention uses natural ingredients such as Hevea brasiliensis, pine tar and rosemary extract to reduce the use of chemical synthetic substances, thereby reducing the generation of volatile organic matter and increasing the environmental protection effect.

[0114] Lead content: the lead contents of test groups A, B and C were 0.001%, 0.0008% and 0.0006%, respectively, which were lower than 0.003% of control group A, 0.0025% of control group B and 0.002% of control group C. This further proves that the present invention controls the introduction of harmful substances such as heavy metals during the raw material selection and preparation process, thereby increasing environmental protection.

[0115] In summary, the raw material formula and preparation method of Example 3 are the best. From the durability point of view, the wear amount is only 0.08g / cm 2 The tear strength reaches 400N. The Brazilian hevea rubber, gutta-percha and lignin fiber work synergistically to make the sole wear-resistant and tear-resistant, and adapt to complex use environments; in terms of comfort, the compression permanent deformation rate is 12%, and the Shore A hardness is 50, indicating that the elastic recovery after compression is good and the sole is soft. The Brazilian hevea rubber and pine tar work together to provide a comfortable foot feel; in terms of environmental protection, the organic volatile matter content is 0.5%, and the lead content is 0.0006%. Due to the selection of natural ingredients and strict control of raw materials, organic volatiles and heavy metals are reduced, and environmental pollution is reduced; It can be seen that Example 3 performs well in durability, comfort and environmental protection, comprehensively improves the performance of modified rubber, and has a good effect in the application of sole materials.

[0116] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a modified rubber with enhanced durability, characterized in that: The following steps are involved: S1. Raw material preparation: Hevea brasiliensis, gutta-percha, plasticizer, lignin fiber, natural rubber vulcanizer, activator and natural antioxidant; S2, plastication: put the Brazilian hevea rubber into an open mill for plastication. During plastication in the open mill, the roller temperature, roller distance and thickness are adjusted to improve the plasticity of the rubber, so as to facilitate the uniform dispersion of other compounding ingredients during subsequent mixing; S3, masterbatch mixing: the plasticized Brazilian hevea rubber is placed in an open mixer, and the roller temperature and roller distance are adjusted, and then the plasticizer, lignin fiber and activator are added in sequence for mixing to make the components evenly dispersed. After the mixing is completed, the masterbatch is cooled and set aside; S4, final rubber mixing: the cooled masterbatch is put back into the open mill, gutta-percha is added, the open mill is mixed, and the roller temperature, roller distance and mixing time are adjusted to make the gutta-percha and the masterbatch fully mixed, then, the natural rubber vulcanizer and the natural antioxidant are added to continue mixing, and the roller temperature, roller distance and mixing time are adjusted. After the mixing is completed, the final rubber is unrolled and cooled to room temperature; S5, vulcanization molding: the cooled final rubber is weighed according to the weight requirements of the sole mold, and is placed in a preheated vulcanization mold for vulcanization, and the temperature, pressure and vulcanization time of the vulcanization mold are set. After the vulcanization is completed, the sole product is taken out and demolded to obtain a modified rubber sole with enhanced durability.

2. The method for preparing a modified rubber with enhanced durability according to claim 1, characterized in that: The S1 includes the following raw materials: The dosage of Brazilian hevea is 50-60 parts; The amount of gutta-percha used is 12-20 parts; The amount of plasticizer is 6-10 parts; The amount of lignin fiber is 4-8 parts; The dosage of natural rubber vulcanizer is 1.2-3 parts; The dosage of the active agent is 4-7 parts; The dosage of natural antioxidant is 1.2-3 parts.

3. The method for preparing a modified rubber with enhanced durability according to claim 1, characterized in that: In S1, the plasticizer is pine tar; the natural rubber vulcanizer is sulfur; the activator is zinc oxide and stearic acid, wherein the amount of zinc oxide is 3-5 parts and the amount of stearic acid is 1-2 parts; and the natural antioxidant is rosemary extract.

4. The method for preparing a modified rubber with enhanced durability according to claim 1, characterized in that: In S2, the roller temperature is adjusted to 50°C-60°C, the roller distance is adjusted to 1mm-2mm, and the thin pass is controlled to 5-8 times.

5. The method for preparing a modified rubber with enhanced durability according to claim 1, characterized in that: In S3, the roller temperature is adjusted to 60° C.-70° C., and the roller distance is adjusted to 3 mm-5 mm.

6. The method for preparing a modified rubber with enhanced durability according to claim 1, characterized in that: In S3, the plasticizer, lignin fiber and active agent are mixed for 12 minutes to 15 minutes.

7. The method for preparing a modified rubber with enhanced durability according to claim 1, characterized in that: In the S4, gutta-percha is added, the roller temperature is adjusted to 60° C.-70° C., the roller distance is adjusted to 3 mm-5 mm, and the mixing time is 5 min-8 min.

8. The method for preparing a modified rubber with enhanced durability according to claim 1, characterized in that: In S4, natural rubber vulcanizer and natural antioxidant are added and mixing is continued, the roller temperature is adjusted to 40° C.-50° C., the roller distance is adjusted to 6 mm-8 mm, and the mixing time is 5 min-8 min.

9. The method for preparing a modified rubber with enhanced durability according to claim 1, characterized in that: In S5, the temperature of the vulcanization mold is 150° C.-160° C., the pressure is 10 MPa-15 MPa, and the vulcanization time is 15 min-30 min.

10. Use of the modified rubber produced by the method for preparing the modified rubber with enhanced durability according to any one of claims 1 to 9 in a sole material.

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