Natural environment-friendly degradable rubber sole and preparation method thereof

Abstract

The invention provides a natural environment-friendly degradable rubber sole and a preparation method thereof. The natural environment-friendly degradable rubber sole is prepared from the following components in parts by weight: 50 to 70 parts of natural rubber, 35 to 45 parts of oak bark fiber, 20 to 30 parts of straw residue, 15 to 20 parts of soybean oil, 12 to 15 parts of hydrated silicon dioxide, 5 to 8 parts of lignocellulose, 3 to 5 parts of soybean protein, 0.5 to 0.7 part of rosin, 1 to 1.5 parts of polyethylene glycol, 2 to 5 parts of sulfur and 0.5 to 1 part of accelerant. The preparation method comprises the following steps: preparing the oak bark fibers, then mixing the oak bark fibers with the natural rubber and the straw residues, and internally mixing to obtain a mixture; then adding vegetable oil and half of soybean oil, hydrated silicon dioxide, lignocellulose, soybean protein, rosin, polyethylene glycol, sulfur and an accelerant, mixing and milling, and then adding the rest formula to continuously mix; and finally, plasticizing, granulating, vulcanizing, cooling, open milling, mould pressing and the like, and then cooling to obtain a finished product. The rubber sole prepared by the preparation method provided by the invention has the advantages of being natural, environment-friendly and degradable.

Description

Technical Field

[0001] The present invention relates to the field of sole materials, and particularly to a natural, environmentally friendly and degradable rubber sole and a preparation method thereof. Background Art

[0002] In recent years, with the rapid rise of the global temperature, people's awareness of environmental protection has gradually awakened. Organic pollutants such as plastics and rubbers are everywhere in life. These pollutants that are difficult to degrade naturally seriously affect our lives. Therefore, we need to take corresponding measures to protect the environment. People's living standards are getting higher and higher, and the quality requirements for shoe products are also getting higher and higher. In the shoe-making industry, we often use a large amount of high molecular polymers that are difficult to degrade naturally. Because high molecular polymers have the advantages of high elasticity, high wear resistance, good softness, acid and alkali resistance, etc., they are widely used in many products. However, such high molecular polymers often contain toxic substances and degrade very slowly naturally. The toxic substances are released and infiltrated into the soil, causing more serious environmental pollution. There are also some synthetic soles made of natural rubber, which have the advantages of light weight, good elasticity, heat insulation, shock absorption and good comfort. However, the current rubber synthetic soles on the market also have the disadvantages of being non-degradable and non-environmentally friendly. Summary of the Invention

[0003] Based on the above problems, the purpose of the present invention is to provide a natural, environmentally friendly and degradable rubber sole and a preparation method thereof.

[0004] In view of the above problems, the following technical solutions are provided: A natural, environmentally friendly and degradable rubber sole, characterized by comprising the following components in parts by weight: 50 - 70 parts of natural rubber, 35 - 45 parts of oak bark fiber, 20 - 30 parts of straw residue, 15 - 20 parts of soybean oil, 12 - 15 parts of hydrated silica, 5 - 8 parts of wood cellulose, 3 - 5 parts of soybean protein, 0.5 - 0.7 parts of rosin, 1 - 1.5 parts of polyethylene glycol, 2 - 5 parts of sulfur, and 0.5 - 1 part of accelerator; The oak bark fiber is prepared by the following method: The oak bark is crushed and dried to obtain a crushed product. The crushed product is added to an alkali solution and mixed evenly, and then cooked at 120 - 140 °C for 2 - 3 h, filtered, washed to neutral, and dried to obtain alkali-treated oak bark fiber. The alkali-treated oak bark fiber is neutralized with glacial acetic acid, washed with clean water and dried to obtain oak bark fiber; The preparation method of the natural, environmentally friendly and degradable rubber sole includes the following steps: Add natural rubber, oak bark fiber and straw residue into a mixer according to the formula ratio, and mix for 15 - 25 min under the condition of 600 - 750 r / min to obtain a mixture; Add the mixture obtained in step (1) into an internal mixer for masterbatch mixing. The internal mixing temperature is 110 - 130 °C, and mix for 10 - 15 min. Add vegetable oil, half of the amount of soybean oil, hydrated silica, wood cellulose, soy protein, rosin, polyethylene glycol, sulfur, and accelerator into the internal mixer in step (2) for mixing. The internal mixing temperature is 110 - 130 °C, and mix for 5 - 10 min. Add the remaining amount of soybean oil, hydrated silica, wood cellulose, soy protein, rosin, polyethylene glycol, sulfur, and accelerator into the internal mixer in step (3) for mixing. The internal mixing temperature is 110 - 130 °C, and mix for 10 - 15 min. Plasticize and extrude the mixture after internal mixing in step (4) with a screw extruder, and cool it after extrusion. Pelletize the product obtained in step (5) with a pelletizer to obtain pellets with a particle size of 3 - 4 mm. Put the particles in step (6) into a vulcanizer and vulcanize at 50 MPa - 130 MPa and 140 °C - 160 °C for 4 - 7 min. After leaving the vulcanizate obtained in step (7) at room temperature for 5 - 8 hours, add it to an open mill for mixing, and then put it into a mold for molding. After cooling, the finished product is obtained.

[0005] The present invention is further provided as follows: It includes the following components in parts by weight: 60 parts of natural rubber, 40 parts of oak bark fiber, 25 parts of straw residue, 18 parts of soybean oil, 14 parts of hydrated silica, 6 parts of wood cellulose, 4 parts of soy protein, 0.6 part of rosin, 1.2 parts of polyethylene glycol, 4 parts of sulfur, and 0.8 part of accelerator.

[0006] The present invention is further provided that the particle size of the straw residue is 100 - 150 mesh.

[0007] The present invention is further provided that when the crushed product of oak bark is mixed with an alkali solution, the alkali solution is a sodium hydroxide solution with a mass fraction of 0.05 - 0.1, and the mass ratio of the crushed product to the alkali solution is 1:(4 - 6), based on the mass of the crushed product.

[0008] The beneficial effects of the present invention: The sole provided in this application uses a high proportion of natural rubber to replace industrial rubbers such as petroleum derivative materials. It not only maintains the original rubber physical properties of the sole but also facilitates the degradation process of microorganisms during subsequent degradation, truly achieving environmental protection and biodegradability. In the technical solution provided by this application, oak bark fiber, straw residue, lignocellulose, and soy protein are intertwined with each other during mixing, and there are many uneven sites on the surface. Under the action of soybean oil, hydrated silica, rosin, polyethylene glycol, sulfur, and accelerator, when combined with natural rubber, natural rubber can easily enter these sites and closely cooperate with the intertwined structure of oak bark fiber, straw residue, lignocellulose, and soy protein, making the entire system a uniform whole. Soybean oil and hydrated silica are grafted onto natural rubber, enhancing the plasticity and elasticity of the rubber. Rosin increases the friction coefficient of the rubber, and when mixed with fibers, it improves the dispersion of the fibers in the rubber, playing a role in steadily enhancing the wear resistance of the sole. Oak bark fiber, straw residue, lignocellulose, and soy protein have certain toughness, wear resistance, and hardness, making the rubber not easily break, with good softness, extensibility, and bendability. It can withstand multiple bends, stretches, and compressions without being damaged, has high acid and alkali resistance, and while maintaining the beautiful appearance of the product, it also has natural degradability, enabling the manufactured shoe products to achieve a good degradation rate within a few years after being discarded, solving the problem that the natural degradation rate of organic substances such as processed rubber after shoe products are discarded is slow and seriously pollutes the environment.

[0009] The oak bark fiber of this application is an important renewable biomass resource. First, the oak bark is cooked with lye to fully soften and swell the oak bark, eliminate a certain amount of lignin, remove the impurities on its surface, increase its specific surface area, increase the contact area between the rubber material and the oak bark fiber, and improve the mechanical bite force. At the same time, it can not only improve the degradation effect of the rubber sole, but also, in combination with straw residue and lignocellulose, further improve the reinforcing effect on natural rubber, thereby improving the mechanical properties of the sole material. Specific Embodiments

[0010] The following combines examples to further describe in detail the specific embodiments of the present invention. The following examples are used to illustrate the present invention, but are not used to limit the scope of the present invention. Examples

[0011] Unless otherwise specified, the chemical reagents used in this application are all commercially available.

[0012] A natural environmentally friendly degradable rubber sole includes the following components: natural rubber, oak bark fiber, straw residue, soybean oil, hydrated silica, lignocellulose, soy protein, rosin, polyethylene glycol, sulfur, accelerator; The particle size of the straw residue is 120 mesh; the accelerator is accelerator CBS; the specific dosage of each raw material is shown in Table 1.

[0013] The embodiment of this application also discloses a preparation method of a natural environmentally friendly degradable rubber sole, including the following steps: A. Prepare oak bark fiber: The oak bark fiber is prepared by the following method: The oak bark is crushed and dried to obtain a crushed product. The crushed product is added to an alkali solution and mixed evenly, and then steamed at 130 °C for 2.5 h, filtered, washed until neutral, and dried to obtain alkali-treated oak bark fiber. The alkali-treated oak bark fiber is washed with clean water in glacial acetic acid and dried to obtain oak bark fiber; In this step, the alkali solution is a sodium hydroxide solution with a mass fraction of 0.08, and the mass ratio of the crushed product to the alkali solution is 1:5.

[0014] B. Preparation of the mixture: (1) Add natural rubber, oak bark fiber and straw residue to a blender according to the formula ratio, and mix for 20 min under the condition of 650 r / min to obtain a mixture; (2) Add the mixture obtained in step (1) to an internal mixer for master rubber mixing, the mixing temperature is 120 °C, and mix for 15 min; (3) Add vegetable oil, half of the amount of soybean oil, hydrated silica, wood cellulose, soy protein, rosin, polyethylene glycol, sulfur and accelerator to the internal mixer in step (2) for mixing, the mixing temperature is 120 °C, and mix for 8 min; (4) Add the remaining soybean oil, hydrated silica, wood cellulose, soy protein, rosin, polyethylene glycol, sulfur and accelerator to the internal mixer in step (3) for mixing, the mixing temperature is 120 °C, and mix for 12 min; (5) Plasticize and extrude the mixture after mixing in step (4) with a screw extruder, and cool it after extrusion; (6) Granulate the product obtained in step (5) with a granulator to obtain pellets with a particle size of 3 mm; (7) Put the particles in step (6) into a vulcanizer and vulcanize at 90 MPa and 150 °C for 5 min; After the vulcanizate obtained in step (7) is placed at room temperature for 7 hours, it is added to a roll mill for rolling, and after rolling, it is put into a mold for molding, and the finished product is obtained after cooling.

[0015] Examples 1 - 5 Prepare according to the above preparation method of the natural environmentally friendly degradable rubber sole. Table 1 is the ingredient table of the natural environmentally friendly degradable rubber sole composition of Examples 1 to 5. The difference between different examples lies in: the dosages of each raw material are different, and the details are shown in Table 1.

[0016] Table 1 Ingredient table of the natural environmentally friendly degradable rubber sole composition of Examples 1 to 5 Component / parts Example 1 Example 2 Example 3 Example 4 Example 5 Natural rubber 50 70 60 65 60 Oak bark fiber 35 45 40 42 37 Straw residue 20 30 25 28 25 Soybean oil 15 20 18 19 22 Hydrated silica 12 15 14 14.5 13 Wood cellulose 5 8 6 7 5.5 Soybean protein 3 5 4 4.5 3.5 Rosin 0.5 0.7 0.6 0.6 0.6 Polyethylene glycol 1 1.5 1.2 1.2 1.2 Sulfur 2 5 4 4 4 Accelerator 0.5 1 0.8 0.8 0.8 Example

[0017] A preparation method of a natural, environmentally friendly and degradable rubber sole, which is different from Example 3 in that: step A is omitted.

[0018] That is, when preparing the mixture in step B, the rubber bark fiber that is mixed with natural rubber and straw residue is the rubber bark fiber that has not been treated with alkali. Example

[0019] A preparation method of a natural, environmentally friendly and degradable rubber sole, which is different from Example 3 in that: in the preparation of rubber bark fiber in step A, the alkali solution is replaced with water. Example

[0020] A preparation method of a natural, environmentally friendly and degradable rubber sole, which is different from Example 3 in that: during the alkali treatment in step A, the mass ratio of the pulverized material to the alkali solution is 1:8.

[0021] Comparative example Comparative example 1 A natural, environmentally friendly and degradable rubber sole, which is different from Example 3 in that: natural rubber is replaced with styrene-butadiene rubber. The amount of natural rubber is 0, and the amount of styrene-butadiene rubber is 60 parts.

[0022] Comparative example 2 A natural, environmentally friendly and degradable rubber sole, which is different from Example 3 in that: rubber bark fiber is replaced with sugarcane fiber. The amount of rubber bark fiber is 0, and the amount of sugarcane fiber is 40 parts.

[0023] Comparative example 3 A natural, environmentally friendly and degradable rubber sole, which is different from Example 3 in that: straw residue is replaced with coffee grounds. The amount of straw residue is 0, and the amount of coffee grounds is 25 parts.

[0024] Comparative example 4 A natural, environmentally friendly and degradable rubber sole, which is different from Example 3 in that: soybean oil is replaced with kerosene. The amount of soybean oil is 0, and the amount of kerosene is 18 parts.

[0025] Comparative example 5 A natural, environmentally friendly and degradable rubber sole, which is different from Example 3 in that: there are 15 parts of rubber bark fiber, 50 parts of straw residue, and 30 parts of soybean oil.

[0026] Performance detection test Put the sole materials of Examples 1-5 and Comparative Examples 1-5 into a heat setting mold, control the heat setting temperature at 160 °C and the time at 30 min to obtain a natural, environmentally friendly and degradable rubber sole.

[0027] Degradation test: Cut the natural environment-friendly degradable rubber soles prepared in Examples 1-5 and Comparative Examples 1-5 into samples of 25 cm * 25 cm * 4 cm, and weigh m1; then bury them in natural soil at a depth of 25 cm and an environmental temperature of 26 °C. After 6 months, take out the samples and weigh m2, and calculate the degradation degree according to the following formula. The higher the degradation degree, the better the degradation effect.

[0028] 2. Tensile strength: Refer to GB / T 10654-2001 "Determination of Tensile Strength and Elongation at Break of High Polymer Porous Elastic Materials", and conduct tensile strength tests on the natural environment-friendly degradable rubber soles prepared in Examples 1-5 and Comparative Examples 1-5, and record the tensile strength.

[0029] 3. Tear strength: Refer to GB / T 10808-2006 "Determination of Tear Strength of High Polymer Porous Elastic Materials", and conduct tear strength tests on the natural environment-friendly degradable rubber soles prepared in Examples 1-5 and Comparative Examples 1-5, and record the tear strength.

[0030] 4. Rebound rate: Refer to GB / T 1681-2009 "Determination of Rebound Resilience of Vulcanized Rubber", and conduct rebound rate tests on the natural environment-friendly degradable rubber soles prepared in Examples 1-5 and Comparative Examples 1-5, and record the rebound rate.

[0031] The test data of the above Tests 1-3 are shown in Table 2. Table 2 Test data of performance tests 1-3 For non-degradable rubber products on the market, the degradation degree is about 1%. Comparative Examples 1-4 are sole materials prepared by arbitrarily substituting one of natural rubber, oak bark fiber, straw residue, and soybean oil on the basis of Example 3. These sole materials are made into rubber soles, and the degradation degree is between 15-28.1%, which is lower than the degradation degree of 31.7% in Example 3. In terms of the detection of the mechanical properties of the rubber soles prepared in Comparative Examples 1-4, the tensile strength is 8-14.1 MPa, the tear strength is 31-35.4 KN / m, and the rebound rate is 51-53%, far inferior to 32.6 MPa, 63.8 KN / m, and 65% in Example 3.

[0032] It shows that simply relying on the selection of degradable raw materials, although the prepared rubber soles can have a certain degradation effect, their mechanical properties are very poor. When further limiting the selected materials to natural rubber, oak bark fiber, straw residue, and soybean oil, not only can the degradation effect be improved and rapid degradation be achieved, but also finished products with high tensile strength, tear strength, and rebound rate can be obtained.

[0033] Combined with Comparative Example 5, Comparative Example 5 is based on Example 3, and the dosage ratio among oak bark fiber, straw residue, and soybean oil is disrupted. The degradation degree of Comparative Example 5 is 30.5%, the tensile strength is 15.7 MPa, the tear strength is 36.1 KN / m, and the resilience rate is 55%. Although it is slightly better than Comparative Examples 1-4, it is still significantly inferior to the excellent performance of Example 3.

[0034] It shows that not only the use of natural rubber, oak bark fiber, straw residue, and soybean oil in the formula needs to be limited, but also the dosage ratio among the four needs to be further limited. If the dosage ratio among the four is disrupted rashly, a rubber material with excellent mechanical properties and rapid degradation still cannot be obtained.

[0035] In Example 5, on the premise that the dosages of natural rubber, oak bark fiber, and straw residue are stable, the dosage of soybean oil is increased. According to the comparison of the test data of Example 3 and Example 5 in Table 2, although Example 5 still shows a good degradation effect, its mechanical properties are affected. It shows that the dosage of soybean oil is not the more the better, and it needs to be further limited within a certain range to have a better matching effect with natural rubber, oak bark fiber, and straw residue.

[0036] In Example 6, on the basis of Example 3, the treatment of oak bark fiber is omitted. According to the comparison of the test data of Example 3 and Example 6 in Table 2, the degradation degree and mechanical properties of Example 6 both decrease. It shows that the treatment of oak bark fiber can effectively increase the roughness of the surface of oak bark fiber, making it easier for straw residue and natural rubber to cooperate with the two, generating a more compact structure, and effectively improving the strength of the finished product made of the rubber material.

[0037] In Examples 7 and 8, on the basis of Example 3, the use of alcohol solution in the preparation of oak bark fiber is changed. The degradation degree of the rubber finished product made of this material decreases, and the tensile strength, tear strength, and resilience rate also decrease. It shows that the use of alkali solution can effectively remove impurities in oak bark fiber and promote a series of subsequent cooperations.

[0038] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A natural, environmentally friendly and degradable rubber sole, characterized in that, It comprises the following components in parts by weight: 50 - 70 parts of natural rubber, 35 - 45 parts of oak bark fiber, 20 - 30 parts of straw residue, 15 - 20 parts of soybean oil, 12 - 15 parts of hydrated silica, 5 - 8 parts of lignocellulose, 3 - 5 parts of soy protein, 0.5 - 0.7 parts of rosin, 1 - 1.5 parts of polyethylene glycol, 2 - 5 parts of sulfur, 0.5 - 1 part of accelerator; The oak bark fiber is prepared by the following method: The oak bark is crushed and dried to obtain a crushed product. The crushed product is added to an alkali solution and mixed evenly, and then steamed at 120 - 140 °C for 2 - 3 h, filtered, washed until neutral, and dried to obtain alkali-treated oak bark fiber. The alkali-treated oak bark fiber is neutralized with glacial acetic acid, washed with water and dried to obtain oak bark fiber; The preparation method of the natural environmental protection and degradable rubber sole comprises the following steps: Add natural rubber, oak bark fiber and straw residue into a mixer according to the formula ratio, and mix for 15 - 25 min under the condition of 600 - 750 r / min to obtain a mixture; Add the mixture obtained in step (1) into an internal mixer for main rubber mixing, the mixing temperature is 110 - 130 °C, and mix for 10 - 15 min; Add vegetable oil and half of the amount of soybean oil, hydrated silica, lignocellulose, soy protein, rosin, polyethylene glycol, sulfur and accelerator into the internal mixer in step (2) for mixing, the mixing temperature is 110 - 130 °C, and mix for 5 - 10 min; Add the remaining amount of soybean oil, hydrated silica, lignocellulose, soy protein, rosin, polyethylene glycol, sulfur and accelerator into the internal mixer in step (3) for mixing, the mixing temperature is 110 - 130 °C, and mix for 10 - 15 min; Plasticize and extrude the mixture after mixing in step (4) with a screw extruder, and cool it after extrusion; Granulate the product obtained in step (5) with a granulator to obtain pellets with a particle size of 3 - 4 mm; Put the particles in step (6) into a vulcanizer and vulcanize at 50 MPa - 130 MPa, 140 °C - 160 °C for 4 - 7 min; After the vulcanizate obtained in step (7) is placed at room temperature for 5 - 8 hours, add it to an open mill for open milling, and then put it into a mold for molding, and cool to obtain the finished product.

2. The natural environmental protection degradable rubber sole according to claim 1, characterized in that, It comprises the following components in parts by weight: 60 parts of natural rubber, 40 parts of oak bark fiber, 25 parts of straw residue, 18 parts of soybean oil, 14 parts of hydrated silica, 6 parts of lignocellulose, 4 parts of soy protein, 0.6 parts of rosin, 1.2 parts of polyethylene glycol, 4 parts of sulfur, 0.8 part of accelerator. A natural, environmentally friendly and degradable rubber sole according to claim 1, characterized in that: The particle size of the straw residue is 100 - 150 mesh. A preparation method of a natural, environmentally friendly and degradable rubber sole according to claim 1, characterized in that: When the crushed product of the oak bark is mixed with the alkali solution, the alkali solution is a sodium hydroxide solution with a mass fraction of 0.05 - 0.1, and the mass ratio of the crushed product to the alkali solution is 1:(4 - 6), based on the mass of the crushed product.