CN114426711A

CN114426711A - Rubber composition based on nitrile rubber and natural rubber and application thereof, vulcanized rubber and preparation method and application thereof

Info

Publication number: CN114426711A
Application number: CN202011074181.4A
Authority: CN
Inventors: 郑方远; 刘苹; 李绍宁; 段海东; 乔勋昌
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2020-10-09
Filing date: 2020-10-09
Publication date: 2022-05-03
Anticipated expiration: 2040-10-09
Also published as: CN114426711B

Abstract

The invention relates to the field of rubber, and discloses a rubber composition based on nitrile rubber and natural rubber and application thereof, vulcanized rubber and a preparation method and application thereof. The vulcanized rubber prepared from the rubber composition provided by the invention has good processability, moderate Mooney viscosity of rubber compound, low shrinkage rate of products, good tensile strength, tearing strength and flexing resistance of the vulcanized rubber, and excellent acid-base and oil resistance.

Description

Rubber composition based on nitrile rubber and natural rubber and application thereof, vulcanized rubber and preparation method and application thereof

Technical Field

The invention relates to the field of rubber sole materials, in particular to a rubber composition based on nitrile rubber and natural rubber, application thereof, a method for preparing vulcanized rubber, the vulcanized rubber prepared by the method and application of the vulcanized rubber in labor protection soles.

Background

The sole material is one of the important application fields of rubber, and different contact environments have different requirements on the performance of the sole material. For example, labor protection shoe soles often require materials with excellent corrosion resistance while simultaneously compromising the high strength and tear resistance of the material.

The sole material is often formed by mould pressing, so that the processing performance of the rubber is higher. On the one hand, a moderate Mooney viscosity of the rubber mixtures is required. Too high Mooney viscosity of the rubber compound often causes insufficient fluidity of the rubber compound, so that the rubber compound cannot be completely filled, thereby causing the increase of defective rate; too low a Mooney viscosity of the compound results in insufficient stiffness of the compound, which affects the preparation of the semi-finished product and the properties of the final vulcanized rubber. On the other hand, excellent dimensional stability (i.e., lower shrinkage) of the vulcanized rubber is required. After the rubber compound is vulcanized, the thickness of the product is larger than the size of the molding part of the mold due to the elastic effect of the rubber. The higher the rubber shrinkage, the more unfavorable the selection of the mold size and the processing conditions.

At present, relevant reports have been made on rubber compositions for shoe soles, particularly on rubber compositions for shoe soles based on nitrile rubber.

CN102796292A discloses a high-elongation wear-resistant oil-resistant rubber sole and a preparation method thereof, the invention solves the problems of poor oil-resistant capability, poor wear resistance and low elongation of the existing rubber shoe sole by designing a sizing material formula of the rubber shoe sole, processing conditions of sole rubber and a vulcanization process of the sole, and improves the wear-resistant performance, the oil-resistant performance and the service life of the rubber shoe sole.

CN104277274A discloses an oil-resistant anti-slip rubber sole and a preparation method thereof, the invention adopts epoxidized rubber as base rubber and combines nitrile rubber with high acrylonitrile content, the sole has good oil resistance, has good anti-slip performance on an oil pollution interface, and has good wear resistance and wide application range.

Due to the introduction of the acrylonitrile structural unit with strong polarity in the molecular chain, the nitrile rubber has excellent oil resistance, and is suitable for producing sole materials with higher requirements on oil resistance. However, the single nitrile rubber cannot meet the performance requirement of diversified labor insurance shoe soles, and the nitrile rubber products are endowed with more service performance by proper processing and application technical means.

The natural rubber is general rubber with the largest use amount, and has a series of advantages of excellent processing performance, good physical performance and the like. The nitrile rubber is hopeful to endow special service performance to rubber products through blending modification of natural rubber.

However, the preparation of the nitrile rubber/natural rubber composite material has great technical difficulty, mainly because the nitrile rubber and the natural rubber have great molecular chain polarity difference to cause poor compatibility of the two base materials, and in addition, the two rubbers have great difference in the types and the use amounts of the matching systems, so that the blending of the two rubbers needs to strictly control the use ratio, and the excellent properties of the two base materials can be fully exerted by adjusting the proper matching system.

Disclosure of Invention

The invention aims to solve the problems that the service performance of a nitrile rubber product provided by the prior art is not enough diversified and the technical difficulty in preparing a nitrile rubber/natural rubber composite material is high, and provides a rubber composition and vulcanized rubber based on nitrile rubber and natural rubber and a preparation method thereof.

In order to achieve the above object, a first aspect of the present invention provides a rubber composition based on a nitrile rubber and a natural rubber, wherein the composition contains two or more of the following components stored in admixture or independently:

the rubber comprises a rubber matrix, polyvinyl chloride, carbon black, white carbon black, acrylic acid metal salts, calcium sulfate whiskers, a silane coupling agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization activator, an anti-aging agent and a plasticizer, wherein the rubber matrix is a combination of nitrile rubber and natural rubber, and the natural rubber is standard rubber and/or smoke sheet rubber;

wherein, in the rubber matrix, the content weight ratio of the nitrile rubber to the natural rubber is 80:20 to 60: 40;

the rubber substrate comprises, by weight, 100 parts of a rubber substrate, 10-30 parts of polyvinyl chloride, 40-80 parts of carbon black, 5-25 parts of white carbon black, 10-30 parts of acrylic metal salt, 5-15 parts of calcium sulfate whisker, 1-3 parts of a silane coupling agent, 1-3 parts of a vulcanizing agent, 1-3 parts of a vulcanization accelerator, 3-10 parts of a vulcanization activator, 2-8 parts of an anti-aging agent and 10-40 parts of a plasticizer.

A second aspect of the present invention provides a method for preparing a vulcanized rubber, the method comprising: the rubber composition of the first aspect is prepared by kneading the respective components to form a kneaded material, and then vulcanizing the kneaded material.

A third aspect of the present invention provides a vulcanized rubber prepared by the above-described method.

The fourth aspect of the present invention provides the use of the above vulcanized rubber in a labor insurance sole.

The fifth aspect of the invention provides the use of the rubber composition described above in the preparation of a labor insurance sole rubber.

The rubber composition with good processing performance, moderate Mooney viscosity of rubber compound, low shrinkage rate of products, good tensile strength, tearing strength and flexing resistance of vulcanized rubber, and excellent acid-base resistance and oil resistance is prepared by adopting the combination of nitrile rubber and natural rubber as a rubber matrix, blending a specific amount of polyvinyl chloride, and optimizing the dosage of a matching system of carbon black, white carbon black, acrylic acid metal salt, calcium sulfate whisker, a silane coupling agent, a vulcanizing agent, a vulcanization accelerator, a vulcanization activator, an anti-aging agent, a plasticizer and the like.

The rubber compositions according to the invention are particularly suitable for the production of safety shoe soles, depending on the performance characteristics of the material.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

As described above, the first aspect of the present invention provides a rubber composition based on a nitrile rubber and a natural rubber, characterized in that the composition contains two or more of the following components stored in admixture or independently:

Preferably, the nitrile rubber is present in an amount of from 25% to 40% by weight in combination with acrylonitrile structural units and has a Mooney viscosity ML (1+4) at 100 ℃ of from 40 to 80.

Preferably, the polyvinyl chloride has an average polymerization degree of 600 to 2000 and an average molecular weight of 4 to 12 ten thousand.

Preferably, the carbon black has a specific surface area of 35m²/g-130m²/g。

Preferably, the specific surface area of the white carbon black is 70m²/g-250m²/g。

Preferably, the acrylic acid metal salt is a metal acrylate salt and/or a metal methacrylate salt.

Preferably, the acrylic acid-based metal salt is a zinc methacrylate salt and/or a magnesium methacrylate salt.

Preferably, the acrylic acid-based metal salt is zinc methacrylate.

Preferably, the calcium sulfate whiskers have an average aspect ratio of 15-200, preferably 30-80, and an average diameter of 1-6 μm.

Preferably, the silane coupling agent is at least one of bis- [ gamma- (triethoxysilyl) propyl ] tetrasulfide (silicon 69), bis- [3- (triethoxysilyl) propyl ] disulfide (silicon 75), and gamma-methacryloxypropyltrimethoxysilane (KH 570).

Preferably, the vulcanizing agent is sulphur and/or a sulphur donor, preferably sulphur. The sulfur donor is a substance capable of providing sulfur. The sulfur comprises at least one of insoluble sulfur, soluble sulfur and oil-extended sulfur. For example, the vulcanizing agent IS ordinary sulfur S, oil-extended insoluble sulfur IS, or the like.

Preferably, the vulcanization accelerator is at least one of a thiazole accelerator, a thiuram accelerator, and a sulfenamide accelerator.

Preferably, the vulcanization accelerator is at least one of tetramethylthiuram disulfide (accelerator TMTD), N-cyclohexyl-2-benzothiazolesulfenamide (accelerator CZ), and dibenzothiazyl disulfide (accelerator DM).

Preferably, the vulcanization activator is a mixture of a metal oxide and a fatty acid.

Preferably, the curing activator is a combination of zinc oxide and stearic acid.

Preferably, the zinc oxide is contained in an amount of 2 to 7 parts by weight and the stearic acid is contained in an amount of 1 to 3 parts by weight, relative to 100 parts by weight of the rubber matrix.

Preferably, the antioxidant is at least one of quinoline antioxidant, p-phenylenediamine antioxidant, naphthylamine antioxidant and imidazole antioxidant.

Preferably, the antioxidant is at least one of antioxidant RD, antioxidant 4010NA, antioxidant D and antioxidant MB.

Preferably, the plasticizer is a combination of at least one of a coal tar-based plasticizer, a fatty oil-based plasticizer, and a synthetic plasticizer, and at least one of an aromatic oil and a naphthenic oil.

Preferably, the plasticizer is a combination of aromatic oil TDAE and at least one of coumarone resin, phthalate, phosphate and fatty dibasic acid ester.

More preferably, the plasticizer is a combination of at least one of coumarone resin, dioctyl phthalate (plasticizer DOP), tricresyl phosphate (plasticizer TCP), and sebacic acid diester (plasticizer DOS), and aromatic oil TDAE.

As previously mentioned, a second aspect of the present invention provides a process for preparing a vulcanized rubber, the process comprising: the rubber composition of the first aspect is prepared by kneading the respective components to form a kneaded material, and then vulcanizing the kneaded material.

In the present invention, the kneading method is not particularly limited as long as the raw materials of the components of the rubber composition can be uniformly mixed. For example, the components of the rubber composition may be simultaneously kneaded, or several of the components may be kneaded first, and then the remaining components may be added to continue kneading.

However, in order to obtain more excellent processability and more suitable Mooney viscosity, according to a preferred embodiment, the step of subjecting each component in the rubber composition of the aforementioned first aspect to said kneading comprises:

(1) carrying out first mixing on a rubber matrix, polyvinyl chloride and acrylic acid metal salt to obtain first mixed rubber;

(2) carrying out second mixing on carbon black, white carbon black, calcium sulfate whiskers, a silane coupling agent, a vulcanization activator, an anti-aging agent and a plasticizer and the first mixed rubber to obtain second mixed rubber;

(3) and carrying out third mixing on the second mixed rubber, a vulcanizing agent and a vulcanization accelerator to obtain the mixed rubber.

The inventor finds that the method provided by the preferred embodiment of the invention can ensure that the obtained rubber compound has no scorching phenomenon, and has good processing performance, moderate Mooney viscosity of the rubber compound is beneficial to post processing and molding, and the product obtained after subsequent vulcanization has better service performance.

Preferably, the first mixing, the second mixing and the third mixing can be carried out in the existing mixing equipment, such as an open mill or an internal mixer.

Preferably, in step (1), the first mixing is performed in an internal mixer, and the conditions of the first mixing at least satisfy: the rotation speed of the internal mixer is 50-80rpm, the initial mixing temperature is 60-80 ℃, and the mixing time is 2-4 min.

Preferably, in step (2), the second mixing is performed in an internal mixer, and the conditions of the second mixing at least satisfy: the rotation speed of the internal mixer is 50-80rpm, the mixing temperature is not lower than 145 ℃, and the mixing time is 4-6 min.

Preferably, in step (3), the third mixing is performed in an internal mixer, and the conditions of the third mixing at least satisfy: the rotation speed of the internal mixer is 40-60rpm, the initial mixing temperature is 40-60 ℃, and the mixing time is 4-6 min.

Preferably, the conditions of the vulcanization treatment at least satisfy: the vulcanization temperature is 145-175 ℃, the vulcanization pressure is 5-20MPa, and the vulcanization time is 5-70min, and more preferably, the vulcanization treatment conditions at least satisfy: the vulcanization temperature is 150-165 ℃, the vulcanization pressure is 10-18MPa, and the vulcanization time is 20-50 min. The inventor finds that the rubber compound is subjected to the vulcanization treatment, so that the finally prepared vulcanized rubber product is lower in shrinkage rate, better in tensile strength, tearing strength and flexing resistance, and more excellent in acid-base resistance and oil resistance.

As previously mentioned, a third aspect of the present invention provides a vulcanizate prepared by the above-described method.

As previously mentioned, a fourth aspect of the invention provides the use of the above-described vulcanized rubber in a safety shoe sole.

As previously mentioned, a fifth aspect of the invention provides the use of the above rubber composition for the manufacture of a safety shoe sole.

The present invention will be described in detail below by way of examples. In the following examples, all the raw materials used are commercially available ones unless otherwise specified.

The apparatus involved in the following preparation examples and comparative examples is shown in Table 1.

TABLE 1

In the following preparations and comparative examples, the reagents used to prepare the vulcanizates were as follows:

nitrile rubber: the respective contents of incorporated acrylonitrile structural units of designations 2640, 4080 and 3365, respectively, are 26 wt%, 40 wt% and 33 wt%, and the respective Mooney viscosities ML (1+4) at 100 ℃ are 40, 80 and 65, manufactured by Russian-Spiro.

Natural rubber: malaysia No. 20 Standard Natural rubber.

Polyvinyl chloride: the trade mark S1000, the average degree of polymerization is 1000; average molecular weight 6.5 ten thousand, produced by the Chinese petrochemical Qilu division.

Calcium sulfate whisker: the average diameter is 3 mu m, the average length-diameter ratio is 50, and the product is produced by Jiangsu New resources mining company Limited.

Carbon black: the specific surface areas of the N330 and N550 are 73-85 m²/g，36～48m²(ii)/g, available from Zideli chemical technology, Inc. of Dongguan city.

White carbon black: 165MP, the specific surface area is 145-175 m²Per g, available from Kogyo siliconization Ltd.

Zinc methacrylate: industrial grade product, available from the Shanghai Michelle chemical technology, Inc.

Silane coupling agent: bis- [ gamma- (triethoxysilyl) propyl ] tetrasulfide (silicon 69), bis- [3- (triethoxysilyl) propyl ] disulfide (silicon 75), analytically pure product, available from carbofuran chemical company.

Vulcanizing agent: sulfur was purchased from Hechiojiu chemical Co., Ltd.

Vulcanization accelerator (b): promoter TMTD, promoter CZ, promoter DM, purchased from Shanghai Yongyan chemical technology Co., Ltd.

Vulcanization activating agent: zinc oxide and stearic acid were purchased from Weifang Heng Feng chemical Co., Ltd.

An anti-aging agent: antioxidant RD, antioxidant 4010NA, antioxidant D, and antioxidant MB, which are available from Jiangsu Shengao chemical technology Co.

Plasticizer: coumarone resin, plasticizer DOP, plasticizer DOS and plasticizer TCP are purchased from Jinan Henry chemical Co., Ltd. The plasticizer TDAE is produced by Hallowey group company of Han Sheng-Germany.

Unless otherwise specified, 10g is expressed per part by weight in the following examples.

Preparation example 1: preparation of vulcanized rubber

First mixing:

adding nitrile rubber, natural rubber, polyvinyl chloride and acrylic acid metal salt into an internal mixer, setting the initial temperature of the internal mixer and the rotating speed of the internal mixer, and carrying out first mixing to obtain first mixed rubber.

And (3) second mixing:

and lifting the upper top plug of the internal mixer of the first mixing, carrying out second mixing on the carbon black, the white carbon black, the calcium sulfate whisker, the silane coupling agent, the vulcanization activator, the anti-aging agent and the plasticizer and the first mixed rubber to obtain second mixed rubber, and discharging the rubber.

And (3) third mixing:

and adding the second mixing rubber, a vulcanizing agent and a vulcanization accelerator into an internal mixer, setting the initial temperature of the internal mixer and the rotating speed of the internal mixer, carrying out third mixing to obtain a mixed rubber, and discharging the rubber.

The mixed rubber is passed through an open mill with the roller spacing of 0.5mm once, then the roller spacing is adjusted to 5mm, and the obtained open mill rubber is parked for 24 hours after two passes.

The above-mentioned starting rubber was vulcanized on a press vulcanizer having a temperature and a pressure set to obtain a vulcanized rubber, which was designated as Z1. Information on the necessary process conditions and the like in the present production examples are shown in tables 2 and 3.

Unless otherwise specified, the same procedures as in preparation example 1 were followed for the other preparation examples, except that the process conditions and the component formulations were as shown in Table 2, and the component formulations were as shown in Table 3.

TABLE 2

TABLE 3

Comparative example 1

A vulcanizate was prepared according to the recipe and method of preparation 1, except that no natural rubber was used and the final vulcanizate was identified as D1, as shown in Table 4.

Comparative example 2

A vulcanizate was prepared according to the formulation and method of preparation example 1 except that polyvinyl chloride was not used and the final vulcanizate was identified as D2 and is shown in Table 4.

Comparative example 3

A vulcanizate was prepared according to the formulation and method of preparation 1 except that zinc methacrylate was not used and the final vulcanizate was identified as D3 and is shown in Table 4.

Comparative example 4

A vulcanizate was prepared according to the formulation and method of preparation 1, except that calcium sulfate whiskers were not used and the final vulcanizate was identified as D4 and is shown in Table 4.

Comparative example 5

Vulcanized rubber was prepared according to the formulation and method of preparation example 1, except that white carbon black was not used, and the final vulcanized rubber was identified as D5, as shown in Table 4.

The remaining preparation examples and comparative examples were carried out by the same procedures as in preparation example 1, unless otherwise specified, and are specifically shown in Table 4.

TABLE 4

Test example: testing of the Properties of the vulcanizates

(1) Mooney viscosity of the compounded rubber: the Mooney viscosity of the compounded rubber was measured by a Mooney viscometer according to the method specified in GB/T1232.1-2016, at a measuring temperature of 100 ℃ for a preheating time of 1min and for a measuring time of 4min, and the results of the measurement were expressed by ML (1+4) at 100 ℃ and are shown in Table 5.

(2) Shrinkage S of vulcanized rubber: the thickness of the vulcanized sample after standing for 24h was measured and recorded as D, and the thickness of the vulcanization mold as D, and then S ═ D/D-1 × 100%, and the results obtained are shown in table 5.

(3) Tensile strength of vulcanized rubber: the tensile strength was tested by means of a universal tensile machine according to the method specified in GB/T528-2009, where the tensile rate was 500mm/min, the test temperature was 23 ℃, the effective part length of the test specimen was 25mm, and the width was 6 mm. For each set of samples, at least 3 replicates were run and the results were median and are shown in table 5.

(4) Tear strength of vulcanized rubber: the tear strength was tested according to the method specified in GB/T529-2009 and the results are given in Table 5.

(5) The vulcanized rubber has acid resistance, alkali resistance and oil resistance: the vulcanized rubber samples were respectively soaked in 20 wt% sulfuric acid solution, 20 wt% sodium hydroxide solution and 903# standard test oil for 70h, and the volume change and tensile property change of the samples were tested according to the method specified in GB/T1690-2010, and the obtained results are shown in Table 5.

(6) Determination of the flexural Properties of the vulcanizates: the split length was tested 30000 inflections as required in GB/T13934-2006 and the results are shown in Table 5.

TABLE 5

In the production process of rubber molded products (such as sole materials), the Mooney viscosity of the rubber compound is a very important technical index, according to general production experience, the Mooney viscosity of the rubber compound is in the range of 60-80, which is most beneficial to production, and the Mooney viscosity is too high, which causes poor flowability of rubber compounds, the phenomenon of gaps of products and increase of defective rate; too low Mooney viscosity leads to insufficient stiffness of the rubber material, difficult preforming and low production efficiency, and the obtained vulcanized rubber has too low mechanical property. The dimensional stability of the product is also one of the important indexes for producing the molded product, and the shrinkage rate of the product is reduced as much as possible so as to ensure the qualification rate of the finished product in the aspect of dimension. Tensile strength and tear strength are the basic physical properties of a sole material that meet the use requirements. The flexing resistance is an important performance index of the sole material and is the embodiment of the durability of the sole. The acid and alkali resistance and the oil resistance are special use performances of the labor protection shoe material according to different use working conditions, and the performance in the aspect is a condition for meeting the use safety of the labor protection shoe material.

As can be seen from the results in Table 5, the vulcanized rubber prepared from the rubber composition provided by the invention has good processability, moderate Mooney viscosity of the rubber compound, low shrinkage rate of the product, good tensile strength, tear strength and flexing resistance of the vulcanized rubber, and excellent acid and alkali resistance and oil resistance. Therefore, the rubber composition and the vulcanized rubber thereof are suitable for producing labor protection soles.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A rubber composition based on nitrile rubber and natural rubber, characterized in that the composition contains more than two of the following components which are mixed and stored or are respectively and independently stored:

2. The rubber composition according to claim 1, wherein the nitrile rubber has a content of bound acrylonitrile structural units of 25 wt% to 40 wt%, a mooney viscosity ML (1+4) of 40 to 80 at 100 ℃;

preferably, the polyvinyl chloride has an average polymerization degree of 600-2000 and an average molecular weight of 4-12 ten thousand;

preferably, the carbon black has a specific surface area of 35m²/g-130m²/g；

3. The rubber composition according to claim 1 or 2, wherein the acrylic metal salt is a metal acrylate and/or a metal methacrylate;

preferably, the acrylic acid metal salt is a zinc methacrylate salt and/or a magnesium methacrylate salt;

preferably, the acrylic acid-based metal salt is zinc methacrylate.

4. The rubber composition according to any one of claims 1 to 3, wherein the calcium sulfate whiskers have an average aspect ratio of 15 to 200 and an average diameter of 1 to 6 μm;

preferably, the silane coupling agent is at least one of bis- [ gamma- (triethoxysilyl) propyl ] tetrasulfide, bis- [3- (triethoxysilyl) propyl ] disulfide, and gamma-methacryloxypropyltrimethoxysilane.

5. The rubber composition according to any one of claims 1 to 4, wherein the vulcanizing agent is sulfur and/or a sulfur donor; preferably sulfur;

preferably, the vulcanization accelerator is at least one of a thiazole accelerator, a thiuram accelerator and a sulfenamide accelerator;

preferably, the vulcanization accelerator is at least one of tetramethylthiuram disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, and dibenzothiazyl disulfide.

6. The rubber composition according to any one of claims 1 to 5, wherein the vulcanization activator is a mixture of a metal oxide and a fatty acid;

preferably, the vulcanization activator is a combination of zinc oxide and stearic acid, wherein the zinc oxide is contained in an amount of 2 to 7 parts by weight and the stearic acid is contained in an amount of 1 to 3 parts by weight, relative to 100 parts by weight of the rubber matrix.

7. The rubber composition according to any one of claims 1 to 6, wherein the antioxidant is at least one of a quinoline antioxidant, a p-phenylenediamine antioxidant, a naphthylamine antioxidant, and an imidazole antioxidant;

preferably, the plasticizer is a combination of at least one of a coal tar-based plasticizer, a fatty oil-based plasticizer and a synthetic plasticizer and at least one of aromatic oil and naphthenic oil;

preferably, the plasticizer is a combination of aromatic oil TDAE and at least one of coumarone resin, phthalate, phosphate and fatty dibasic acid ester;

preferably, the plasticizer is a combination of at least one of coumarone resin, dioctyl phthalate, tricresyl phosphate and sebacic acid diester, and aromatic oil TDAE.

8. A method of preparing a vulcanizate, the method comprising: mixing the respective components of the rubber composition according to any one of claims 1 to 7 to form a rubber compound, and subjecting the rubber compound to a vulcanization treatment.

9. The method of claim 8, wherein said step of mixing the components comprises:

10. The process according to claim 9, wherein in step (1), the first mixing is carried out in an internal mixer, the conditions of the first mixing being at least: the rotation speed of the internal mixer is 50-80rpm, the initial mixing temperature is 60-80 ℃, and the mixing time is 2-4 min.

11. The process according to any one of claims 9, wherein in step (2), the second mixing is carried out in an internal mixer, the conditions of the second mixing being at least such that: the rotation speed of the internal mixer is 50-80rpm, the mixing temperature is not lower than 145 ℃, and the mixing time is 4-6 min.

12. The process according to any one of claims 9, wherein in step (3), the third mixing is carried out in an internal mixer, the conditions of the third mixing being at least: the rotation speed of the internal mixer is 40-60rpm, the initial mixing temperature is 40-60 ℃, and the mixing time is 4-6 min.

13. The method according to any one of claims 8 to 12, wherein the conditions of the vulcanization process at least satisfy: the vulcanization temperature is 145-175 ℃, the vulcanization pressure is 5-20MPa, and the vulcanization time is 5-70 min.

14. A vulcanized rubber produced by the process of any one of claims 8 to 13.

15. Use of the vulcanizate of claim 14 in a labor shoe sole.

16. Use of the rubber composition according to any one of claims 1 to 7 for the preparation of a rubber for safety shoe soles.