CN114426711B

CN114426711B - Rubber composition based on nitrile rubber and natural rubber, application thereof, vulcanized rubber, and preparation method and application thereof

Info

Publication number: CN114426711B
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: 2023-07-21
Anticipated expiration: 2040-10-09
Also published as: CN114426711A

Abstract

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

Description

Rubber composition based on nitrile rubber and natural rubber, 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 and application of the vulcanized rubber prepared by the method in labor insurance soles.

Background

Sole materials are one of the important application fields of rubber, and different contact environments have different requirements on the performances of the sole materials. For example, labor insurance soles often require materials that have excellent corrosion resistance while simultaneously achieving both high strength and tear resistance.

Because the sole material is often molded by a compression molding method, the processability of rubber is highly required. On the one hand, it is desirable that the compounds have a moderate Mooney viscosity. The excessive Mooney viscosity of the rubber compound often leads to insufficient fluidity of the rubber compound, so that the rubber compound can not be completely filled with the mold, thereby leading to the rise of defective rate; too low a Mooney viscosity of the mix may result in insufficient mix stiffness, thereby affecting the preparation of the semi-finished product and the properties of the final vulcanizate. On the other hand, there is a need for vulcanizates having excellent dimensional stability (i.e., lower shrinkage). After curing the rubber compound will result in a product thickness that is greater than the size of the mold forming section due to the elastic effect of the rubber. The higher the rubber shrinkage, the more detrimental the choice of die dimensions and processing conditions.

At present, there have been reports on rubber compositions for soles, particularly those based on nitrile rubber.

CN102796292a discloses a wear-resistant oil-resistant rubber sole with high elongation and a preparation method thereof, and the invention solves the problems of poor oil-resistant capability, wear resistance and low elongation of the existing rubber sole by designing the rubber formula of the rubber sole, the processing condition of the sole rubber and the vulcanization process of the sole, thereby improving the wear resistance, the oil resistance and the service life of the rubber sole.

CN104277274a discloses an oil-resistant anti-slip rubber sole and a preparation method thereof, the invention adopts epoxidized rubber as matrix rubber, combines nitrile rubber with high acrylonitrile content, has good oil resistance, has good anti-slip performance on an oil pollution interface, has good wear resistance, and has wide application range.

The nitrile rubber has excellent oil resistance due to the introduction of the strong polar acrylonitrile structural unit in the molecular chain, and is suitable for producing sole materials with high oil resistance requirement. However, the pure nitrile rubber cannot meet the performance requirements of labor insurance shoe soles in a diversified manner, and more service performance is required to be provided for the nitrile rubber product through proper processing and application technical means.

The natural rubber is the general rubber with the largest dosage, and has a series of advantages of excellent processability, good physical properties and the like. The nitrile rubber is hopefully endowed with special service performance to rubber products through natural rubber blending modification.

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 polarity difference, which results in poor compatibility of two base materials, and the two rubbers have great difference in the type and the amount of the matched system, so that the blending of the two materials needs to strictly control the use proportion, and the excellent performance of the two base materials can be fully exerted by adjusting the proper matched system.

Disclosure of Invention

The invention aims to solve the problems of insufficient service performance of nitrile rubber products and great technical difficulty in preparing nitrile rubber/natural rubber composite materials in the prior art, 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 nitrile rubber and natural rubber, characterized in that the composition contains the following components stored in a mixture of two or more or each independently:

the rubber comprises a rubber matrix, polyvinyl chloride, carbon black, white carbon black, acrylic metal salt, calcium sulfate whisker, 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 tobacco flake 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 matrix comprises, by weight, 100 parts of a rubber matrix, 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.

In a second aspect, the present invention provides a process for producing a vulcanized rubber, the process comprising: the components in the rubber composition of the first aspect are mixed to form a rubber compound, and the rubber compound is vulcanized.

In a third aspect, the present invention provides a vulcanized rubber prepared by the above method.

A fourth aspect of the present invention provides the use of the above-described vulcanizate in a safety sole.

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

According to the invention, the combination of nitrile rubber and natural rubber is adopted as a rubber matrix, a specific amount of polyvinyl chloride is blended, and the rubber composition with good processability, moderate Mooney viscosity, low product shrinkage, good vulcanized rubber tensile strength, tear strength and flexibility resistance and excellent acid and alkali resistance and oil resistance is prepared through optimization of the dosage of a compounding system of carbon black, white carbon black, acrylic 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 composition of the invention is particularly suitable for producing labor protection soles according to the performance characteristics of materials.

Detailed Description

The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.

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

Preferably, the nitrile rubber has a content of incorporated acrylonitrile structural units of 25wt% to 40wt% and a Mooney viscosity ML (1+4) at 100℃of 40 to 80.

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

Preferably, the specific surface area of the carbon black is 35m ² /g-130m ² /g。

Preferably, the specific surface area of the white carbon black is 70m ² /g-250m ² /g。

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

Preferably, the acrylic metal salt is zinc methacrylate and/or magnesium methacrylate.

Preferably, the acrylic metal salt is zinc methacrylate.

Preferably, the calcium sulfate whiskers have an average aspect ratio of 15 to 200, preferably 30 to 80, and an average diameter of 1 to 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-methacryloxypropyl trimethoxysilane (KH 570).

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

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

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

Preferably, 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.

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 with respect to 100 parts by weight of the rubber substrate.

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

Preferably, the antioxidant is at least one of an antioxidant RD, an antioxidant 4010NA, an antioxidant D and an 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 aromatic oil TDAE and at least one of coumarone resin, dioctyl phthalate (plasticizer DOP), tricresyl phosphate (plasticizer TCP) and diester sebacate (plasticizer DOS).

As previously described, a second aspect of the present invention provides a process for producing a vulcanized rubber, the process comprising: the components in the rubber composition of the first aspect are mixed to form a rubber compound, and the rubber compound is vulcanized.

The manner of kneading is not particularly limited in the present invention, as long as it is possible to uniformly mix the raw materials of the respective components of the rubber composition. For example, the components in the rubber composition may be kneaded simultaneously, or several of the components may be kneaded first, and then the remaining components may be added to continue the kneading.

However, in order to obtain better processability and a more suitable mooney viscosity, according to a preferred embodiment, the step of mixing the components of the rubber composition of the first aspect comprises:

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

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

(3) And thirdly mixing 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 lead the obtained rubber compound not to have scorching phenomenon, has good processing performance and moderate Mooney viscosity of the rubber compound, is beneficial to post-processing molding, and leads the product obtained after the subsequent vulcanization to have better service performance.

Preferably, the first mixing, the second mixing, and the third mixing may be performed in existing mixing equipment, for example, an open mill or an internal mixer.

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

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

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 4-6min.

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

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

As previously mentioned, a fourth aspect of the present invention provides the use of the above-described vulcanizate in a work sole.

As previously mentioned, a fifth aspect of the present invention provides the use of the rubber composition described above in the preparation of a safety sole.

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

The equipment involved in the following preparation examples and comparative examples is shown in table 1.

TABLE 1

In the following preparation examples and comparative examples, the reagents used for preparing the vulcanized rubber were as follows:

nitrile rubber: the contents of bound acrylonitrile structural units were 26wt%,40wt%,33wt% and Mooney viscosity ML (1+4) at 100℃were 40, 80, 65 and Luo Sixi from Boolean company, respectively, under the designations 2640, 4080 and 3365.

Natural rubber: malaysia No. 20 standard Natural rubber.

Polyvinyl chloride: brand S1000, average degree of polymerization is 1000; the average molecular weight is 6.5 ten thousand, and the Chinese petrochemical company is manufactured by Qilu division company.

Calcium sulfate whisker: the average diameter is 3 mu m, the average length-diameter ratio is 50, and the new source mining company of Jiangsu is manufactured.

Carbon black: the marks N330 and N550 have specific surface areas of 73-85 m respectively ² /g，36～48m ² And/g, available from Dongguan city Ji Deli chemical technology Co., ltd.

White carbon black: number 165MP, specific surface area 145-175 m ² And/g, available from certain siliconizing stock, inc.

Zinc methacrylate: industrial grade products, available from Shanghai Michelson chemical Co., ltd.

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

Vulcanizing agent: sulfur, purchased from a constant chemical company in a Weifang.

Vulcanization accelerators: the accelerator TMTD, accelerator CZ, and accelerator DM were purchased from Shanghai Yongsheng chemical technology Co.

Vulcanization activator: zinc oxide, stearic acid, purchased from the Weifang Hengfeng chemical company, inc.

Anti-aging agent: anti-aging agent RD, anti-aging agent 4010NA, anti-aging agent D, anti-aging agent MB, available from Jiangsu san Orchiku chemical Co., ltd.

And (3) a plasticizer: coumarone resin, plasticizer DOP, plasticizer DOS, plasticizer TCP, available from atactic chemical company, inc. The plasticizer TDAE is produced by Hansheng-Luo Shengtai group company of Germany.

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

Preparation example 1: preparation of vulcanized rubber

First mixing:

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

And (3) secondary mixing:

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

And (3) third mixing:

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

The above-mentioned rubber compound was passed once on an open mill with a roll gap of 0.5mm, then the roll gap was adjusted to 5mm, and the obtained rubber compound was parked for 24 hours by passing twice.

The above rubber compound was vulcanized on a press vulcanizer at a set temperature and pressure to obtain vulcanized rubber, which was designated as Z1. Also, the information on the necessary process conditions and the like in this preparation example are shown in tables 2 and 3.

The other preparation examples, unless otherwise specified, used the same procedure as in preparation example 1, except for the process conditions and the component formulations, the specific process conditions are shown in Table 2, and the specific component formulations are shown in Table 3.

TABLE 2

TABLE 3 Table 3

Comparative example 1

Vulcanized rubber was prepared according to the formulation and method of preparation example 1, except that no natural rubber was used, and the finally prepared vulcanized rubber was designated as D1, as shown in Table 4.

Comparative example 2

A vulcanized rubber was prepared according to the formulation and method of preparation example 1, except that polyvinyl chloride was not used, and the finally prepared vulcanized rubber was designated D2, as shown in Table 4.

Comparative example 3

A vulcanized rubber was prepared according to the formulation and method of preparation example 1, except that zinc methacrylate was not used, and the finally prepared vulcanized rubber was designated D3, as shown in Table 4.

Comparative example 4

A vulcanized rubber was prepared according to the formulation and method of preparation example 1, except that calcium sulfate whiskers were not used, and the finally prepared vulcanized rubber was designated D4, as shown in Table 4.

Comparative example 5

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

Unless otherwise specified, the rest of the preparation examples and comparative examples were carried out using the same procedures as in preparation example 1, as shown in Table 4.

TABLE 4 Table 4

Test example: testing of vulcanizate properties

(1) Mooney viscosity of the mixed 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 100℃for a preheating time of 1min and for a measuring time of 4min, and the measurement results were expressed in ML (1+4) at 100℃and the results are shown in Table 5.

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

(3) Tensile strength of vulcanized rubber: the tensile strength was tested by a universal tensile machine according to the method specified in GB/T528-2009, wherein 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 6mm. For each set of samples, at least 3 replicates were run, the median was obtained and the results are shown in table 5.

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

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

(6) Measurement of flex properties of vulcanized rubber: the break length of the flex was tested 30000 times as per GB/T13934-2006, and the results obtained are shown in Table 5.

TABLE 5

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In the production process of rubber molded products (such as sole materials), the Mooney viscosity of the rubber compound is an important technical index, and according to common production experience, the Mooney viscosity of the rubber compound is in the range of 60-80, the rubber compound is most beneficial to production, the Mooney viscosity is too high, the flowability of the rubber compound is poor, the phenomenon of gaps occurs in the product, and the defective rate is increased; the insufficient stiffness of the rubber material caused by the low Mooney viscosity is difficult to preform, the production efficiency is low, and the mechanical property of the obtained vulcanized rubber is low. The dimensional stability of the product is also one of important indexes for producing molded products, and the shrinkage rate of the product should be reduced as much as possible so as to ensure the qualification rate of the finished product in terms of size. Tensile strength and tear strength are the basic physical properties of sole materials to meet the use requirements. The flexibility resistance is an important performance index of the sole material, and is a representation of the durability of the sole. The acid and alkali resistance and the oil resistance are special use performances required by the labor protection shoe material according to different use conditions, and the performances meet the use safety conditions 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 product shrinkage, good tensile strength, tear strength and flexibility resistance, and excellent acid and alkali resistance and oil resistance. Therefore, the rubber composition and the vulcanized rubber thereof are suitable for producing the labor insurance soles.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims

1. A rubber composition based on nitrile rubber and natural rubber is characterized in that the composition contains the following components which are stored in a mixed mode or are stored independently:

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

3. The rubber composition according to claim 1, wherein the polyvinyl chloride has an average polymerization degree of 600 to 2000 and an average molecular weight of 4 to 12 tens of thousands.

4. The rubber composition according to claim 1, wherein the specific surface area of the carbon black is 35m ² /g-130 m ² /g。

5. The rubber composition according to claim 1, wherein the white carbon black has a specific surface area of 70m ² /g-250 m ² /g。

6. The rubber composition according to any one of claims 1 to 5, wherein the acrylic metal salt is a metal acrylate and/or a metal methacrylate.

7. The rubber composition according to any one of claims 1 to 5, wherein the acrylic metal salt is zinc methacrylate salt and/or magnesium methacrylate salt.

8. The rubber composition according to any one of claims 1 to 5, wherein the acrylic metal salt is zinc methacrylate.

9. The rubber composition according to any one of claims 1 to 5, wherein the calcium sulfate whiskers have an average aspect ratio of 15 to 200 and an average diameter of 1 to 6 μm.

10. The rubber composition according to any one of claims 1 to 5, wherein the silane coupling agent is at least one of bis- [ gamma- (triethoxysilane) propyl ] tetrasulfide, bis- [3- (triethoxysilane) propyl ] disulfide, and gamma-methacryloxypropyl trimethoxysilane.

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

12. The rubber composition according to any one of claims 1 to 5, wherein the vulcanizing agent is sulfur.

13. The rubber composition according to any one of claims 1 to 5, wherein the vulcanization accelerator is at least one of a thiazole-based accelerator, a thiuram-based accelerator and a sulfenamide-based accelerator.

14. The rubber composition according to any one of claims 1 to 5, wherein the vulcanization accelerator is at least one of tetramethylthiuram disulfide, N-cyclohexyl-2-benzothiazole sulfenamide, and dibenzothiazyl disulfide.

15. 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.

16. The rubber composition according to any one of claims 1 to 5, wherein the vulcanization activator is a combination of zinc oxide and stearic acid, wherein the zinc oxide content is 2 to 7 parts by weight and the stearic acid content is 1 to 3 parts by weight with respect to 100 parts by weight of the rubber substrate.

17. The rubber composition according to any one of claims 1 to 5, wherein the antioxidant is at least one of a quinoline-based antioxidant, a p-phenylenediamine-based antioxidant, a naphthylamine-based antioxidant and an imidazole-based antioxidant.

18. The rubber composition according to any one of claims 1 to 5, wherein 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.

19. The rubber composition according to any one of claims 1 to 5, wherein the plasticizer is a combination of aromatic oil TDAE and at least one of coumarone resin, phthalate, phosphate and fatty dibasic acid ester.

20. The rubber composition according to any one of claims 1 to 5, wherein the plasticizer is a combination of aromatic oil TDAE and at least one of coumarone resin, dioctyl phthalate, tricresyl phosphate and diester sebacate.

21. A process for preparing a vulcanized rubber, comprising: mixing the components of the rubber composition of any one of claims 1-20 to form a compound, and curing the compound.

22. The method of claim 21, wherein the step of mixing the components comprises:

23. The method of claim 22, wherein in step (1), the first mixing is performed in an internal mixer, and the first mixing conditions 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 2-4min.

24. The method of claim 22, wherein 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 4-6min.

25. A method according to claim 22, 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 4-6min.

26. The method according to any one of claims 21-25, wherein the vulcanization conditions at least satisfy: the vulcanization temperature is 145-175 ℃, the vulcanization pressure is 5-20MPa, and the vulcanization time is 5-70min.

27. A vulcanized rubber prepared by the process of any one of claims 21-26.

28. Use of the vulcanized rubber of claim 27 in a safety sole.

29. Use of the rubber composition of any one of claims 1-20 in the preparation of a labor insurance sole rubber.