Preparation method of fatigue-resistant modified natural rubber material

Abstract

The invention provides a fatigue-resistant modified natural rubber material and a preparation method thereof, and the material is prepared from natural rubber, halogenated polyolefin, zinc oxide, medium super wear-resistant furnace black filler, 2, 4, 6-tris [N-(1, 4-dimethyl amyl)-p-phenylenediamine]-1, 3, 4, 5-tetramethyl-1, 3, 5-tetramethyl-1, 3, 5-tetramethyl-1, 3, 5-tetramethyl-1, 3, 5-tetramethyl-1, 3, 5-tetramethyl-1, 3, the preparation method comprises the following steps: adding chlorinated natural rubber into natural rubber latex, refining, dividing into two parts, respectively adding 2, 4, 6-tris [N-(1, 4-dimethyl amyl)-p-phenylenediamine]-1, 3, 5-triazine and N-isopropyl-N '-phenyl-p-phenylenediamine, refining, adding a vulcanizing agent, a catalyst and an accelerant, and mixing to obtain the rubber latex. Then adding a catalyst for refining, mixing the two materials for refining, and then adding an accelerant, medium super wear-resistant furnace black filler, zinc oxide and a vulcanizing agent for vulcanization treatment to obtain the fatigue-resistant modified natural rubber material. The rubber material has a more stable cross-linked structure and can resist external stress, wear resistance and toughness, and the impact strength of the rubber material can be improved by 25% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of natural rubber modification, and in particular relates to a fatigue-resistant modified natural rubber material and a preparation method thereof. Background Art

[0002] Natural rubber contains unsaturated double bonds in its chain alkenes, with an average of one double bond on every four carbon atoms. Each macromolecular chain segment has many double bonds, which can undergo many reactions, such as vulcanization. It can also react with free radicals, oxygen, ozone, ultraviolet light and free radical inhibitors. In addition, the structure contains donating methyl groups, which increases the electron cloud density of the double bonds and the activity of α-H, making natural rubber more susceptible to reaction and aging, resulting in performance degradation.

[0003] At present, the main way to improve the fatigue and aging resistance of natural rubber is through vulcanization treatment, which allows the double bonds of natural rubber to be vulcanized in advance to enhance the fatigue and aging resistance of natural rubber. However, after the vulcanization treatment, the molecular chains of natural rubber are short, the cross-linking effect between molecules is poor, and the molecular network stability of natural rubber is insufficient, resulting in the fatigue resistance of natural rubber still being low. Summary of the Invention

[0004] The present invention provides a fatigue-resistant modified natural rubber material and a preparation method thereof, aiming to solve the technical problem that the natural rubber has short molecular chains after vulcanization treatment, poor cross-linking effect between molecules, insufficient molecular network stability of the natural rubber, and thus low fatigue resistance of the natural rubber.

[0005] The technical solution provided by the present invention is a fatigue-resistant modified natural rubber material, which is prepared from the following raw materials in parts by weight: 50 parts of natural rubber, 20-40 parts of halogenated polyolefin with a halogen content greater than 40wt%, 0.5-1 part of zinc oxide, 30 parts of medium-super wear-resistant furnace black filler, 40-60 parts of 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine, 20-30 parts of N-isopropyl-N'-phenyl-p-phenylenediamine, 0.8-1.2 parts of a vulcanizing agent, 2-5 parts of a catalyst, and 3-5 parts of an accelerator.

[0006] Preferably, the halogenated polyolefin is one or more of chlorinated chloroprene rubber, chlorinated natural rubber, brominated EPDM rubber or brominated natural rubber.

[0007] Preferably, the average molecular weight of the halogenated polyolefin is 100,000 to 300,000.

[0008] Preferably, the weight ratio of the 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine to N-isopropyl-N'-phenyl-p-phenylenediamine is 2:1.

[0009] Preferably, the catalyst is one of tetramethylammonium hydroxide or alkyl lithium.

[0010] Preferably, the vulcanizing agent is one or more of sulfur, vulcanizing agent S, TMTD, TMRR, TRTD, DTDM, BPO, DCP and DTBP.

[0011] Preferably, the accelerator is one or more of accelerator DETU, accelerator DPG, accelerator BZ, accelerator PZ, accelerator ZDC and accelerator CZ.

[0012] Another object of the present invention is to provide a method for preparing the fatigue-resistant modified natural rubber material, the preparation steps being as follows: S1. Under nitrogen protection, chlorinated natural rubber is added to natural rubber latex for refining. After uniform refining, the mixture is divided into two parts. 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine is added to one part to form component A, and N-isopropyl-N'-phenyl-p-phenylenediamine is added to the other part to form component B. S2. First, a catalyst is added to component A and refined evenly, then component A and component B are mixed and refined, and then a promoter is added and refined to obtain a multi-component copolymer product E; S3. First, mix the super wear-resistant furnace black filler and zinc oxide evenly, then add them to the multi-polymer product E and mix them first, then let them stand and cure for 12 hours, then add the vulcanizing agent, and perform vulcanization treatment in a vulcanizer to obtain a fatigue-resistant modified natural rubber material.

[0013] Preferably, in step S2, the mixing and refining time of component A and component B is 24-36 hours, and the refining time of adding the accelerator is 22-26 hours.

[0014] Preferably, in step S3, the mixing time of the multi-element tool product E is 36-48 hours, and the vulcanization treatment time is 42-48 hours.

[0015] In the above steps, component A and component B are mixed, and excess 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine reacts with N-isopropyl-N'-phenyl-p-phenylenediamine to form amino functional groups. The amino functional groups react with the halogenated polyolefin in the mixture to connect different rubber chains to form a cross-linked structure to obtain a copolymer product C; the copolymer product C is mixed with 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine and natural rubber to form a multi-polymer copolymer product E.

[0016] Zinc oxide and the super wear-resistant furnace black filler react with the hydroxyl groups on the surface of the modified furnace black to form zinc ester groups. The ester groups act as catalysts in the rubber vulcanization process to promote the vulcanization reaction, connect the sulfur atoms in the rubber to form a cross-linked structure, and promote the super wear-resistant furnace black filler and the 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine in the copolymer product C that does not participate in the reaction to form fatigue-resistant rubber materials in the multi-polymer product E during the vulcanization process.

[0017] Compared with the prior art, the embodiments of the present application have the following beneficial effects: 1. The present invention forms an amino functional group by reacting 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine and N-isopropyl-N'-phenyl-p-phenylenediamine; the amino functional group can chemically react with the halogen functional group in the rubber to form a new cross-linking reaction. The new cross-linking reaction introduces a new covalent bond, connects different rubber chains, forms a cross-linking structure, and constructs a more stable molecular network. This network structure can resist external stress and wear, thereby improving the fatigue resistance of the rubber.

[0018] 2. Natural rubber latex is interpenetratingly compounded with halogenated polyolefin elastomer in an inert gas environment, thereby greatly improving the toughness of the composite material and its impact strength can be significantly improved. DETAILED DESCRIPTION

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0020] Example 1 The fatigue-resistant modified natural rubber material provided in Example 1 of the present invention is prepared from the following raw materials in parts by weight: 50 parts of natural rubber, 30 parts of chlorinated natural rubber containing 50% chlorine, 1 part of zinc oxide, 30 parts of medium-super wear-resistant furnace black filler, 50 parts of 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine, 25 parts of N-isopropyl-N'-phenyl-p-phenylenediamine, 1 part of vulcanizing agent, 2.5 parts of catalyst, and 4 parts of accelerator.

[0021] The preparation steps of the above fatigue-resistant modified natural rubber material are as follows: S1. Under nitrogen protection, chlorinated natural rubber is added to natural rubber latex for refining. After uniform refining, the mixture is divided into two parts. 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine is added to one part to form component A, and N-isopropyl-N'-phenyl-p-phenylenediamine is added to the other part to form component B. S2. First, a catalyst is added to component A and refined evenly, then component A and component B are mixed and refined for 30 hours, and then a promoter is added to carry out a refining reaction for 24 hours to obtain a multi-component copolymer product E; S3. First, mix the super wear-resistant furnace black filler with zinc oxide, then add it to the multi-polymer product E and mix it for 42 hours, then let it stand and cure for 12 hours, then add the vulcanizing agent, and perform vulcanization treatment in a vulcanizer for 45 hours to obtain a fatigue-resistant modified natural rubber material.

[0022] Example 2 Compared with Example 1, Example 2 of the present invention has the following technical feature: the halogenated polyolefin is chlorinated chloroprene rubber containing 40% chlorine.

[0023] Example 3 Compared with Example 1, Example 3 of the present invention has the following technical feature: the halogenated polyolefin is brominated EPDM rubber containing 60% bromine.

[0024] Example 4 Compared with Example 1, Example 4 of the present invention has the following technical features: 15 parts of chlorinated natural rubber containing 50% chlorine and 15 parts of brominated natural rubber containing 50% bromine.

[0025] Example 5 Compared with Example 1, Example 5 of the present invention has the following technical feature: the amount of the catalyst used is 2 parts.

[0026] Example 6 Compared with Example 1, Example 6 of the present invention has the following technical feature: the amount of the catalyst used is 3 parts.

[0027] Example 7 Compared with Example 1, Example 7 of the present invention has the following technical feature: the amount of the super wear-resistant furnace black filler is 25 parts.

[0028] Example 8 Compared with Example 1, Example 8 of the present invention has the following technical feature: the amount of the super wear-resistant furnace black filler is 35 parts.

[0029] Example 9 Compared with Example 1, Example 9 of the present invention has the following distinguishing technical features: the amount of 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine is 40 parts, and the amount of N-isopropyl-N'-phenyl-p-phenylenediamine is 20 parts.

[0030] Example 10 Compared with Example 1, Example 10 of the present invention has the following technical characteristics: the amount of 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine is 60 parts, and the amount of N-isopropyl-N'-phenyl-p-phenylenediamine is 30 parts.

[0031] Comparative Example 1 Compared with Example 1, the difference in technical characteristics of Comparative Example 1 is that the amount of zinc oxide used is 0.

[0032] Comparative Example 2 Compared with Example 1, the difference in technical characteristics of Comparative Example 2 is that the amount of super wear-resistant furnace black filler is 0.

[0033] Comparative Example 3 Compared with Example 1, the technical feature of Comparative Example 3 is that after adding chlorinated natural rubber and antioxidant to natural rubber latex, 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine, catalyst, N-isopropyl-N'-phenyl-p-phenylenediamine, accelerator, medium-super wear-resistant furnace black filler, zinc oxide and vulcanizing agent are added in sequence and mixed for 60 hours.

[0034] Comparative Example 4 Compared with Example 1, the difference between Comparative Example 4 and Example 1 is that the amount of 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine is 0.

[0035] The fatigue-resistant modified natural rubber materials prepared in Examples 1 to 10 and Comparative Examples 1 to 4 were tested for tensile strength according to GB / T528-2009 "Determination of tensile stress-strain properties of vulcanized or thermoplastic rubber"; the fatigue resistance of the rubber materials was tested according to GB / T1687.1-2016; the elongation at break was tested according to the national standard GB / T528-1998; and the dynamic fatigue resistance was tested according to the national standard GB / T15584-1995. The detection performance obtained the following results, as shown in Table 1: Table 1 Rubber properties of Examples 1-10 and Comparative Examples 1-4

[0036] It can be seen from Examples 1 to 4 and Comparative Example 4 that different chlorinated polyolefins have a good promoting effect on the modification of rubber materials. At the same time, the amino functional groups formed by 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine and N-isopropyl-N'-phenyl-p-phenylenediamine can significantly improve the fatigue resistance of rubber.

[0037] It can be seen from Example 1 and Comparative Example 1 that the zinc ester group acts as a catalyst in the rubber vulcanization process, promotes the vulcanization reaction, and connects the sulfur atoms in the rubber to form a cross-linked structure, which can improve the fatigue resistance of the rubber to a certain extent.

[0038] As can be seen from Examples 1-10 and Comparative Example 3, the rubber materials prepared by the process of the present invention have excellent tensile strength and a high number of compression fatigue resistance times, indicating that the fatigue-resistant rubber materials prepared by the present invention have good fatigue resistance and can still maintain the strength of the rubber materials after multiple compression fatigue. Since Comparative Examples 1-2 and Comparative Example 4 do not contain zinc oxide, super wear-resistant furnace black filler, and 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine, the performance of the resulting rubber materials is significantly worse than that of the examples. Increasing the content of 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine significantly improves the overall performance of the materials. This is because the amino functional group is formed by the reaction of 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine and N-isopropyl-N'-phenyl-p-phenylenediamine. The amino functional group can react chemically with the halogen functional group in the rubber to form a new cross-linking reaction. The new cross-linking reaction introduces a new covalent bond, connecting different rubber chains to form a cross-linking structure, and constructing a more stable molecular network. This network structure can resist external stress and wear, thereby improving the fatigue resistance of the rubber.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the invention. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on these embodiments, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in this field can still combine, add, delete or make other adjustments to the features in the various embodiments of the present invention according to the circumstances without conflict, without making creative work, so as to obtain different other technical solutions that do not deviate from the concept of the present invention in essence, and these technical solutions also fall within the scope of protection of the present invention.

Claims

1. A fatigue-resistant modified natural rubber material, characterized in that: The invention is prepared from the following raw materials in parts by weight: 50 parts of natural rubber, 20-40 parts of halogenated polyolefin with a halogen content greater than 40wt%, 0.5-1 part of zinc oxide, 30 parts of medium-super wear-resistant furnace black filler, 40-60 parts of 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine, 20-30 parts of N-isopropyl-N'-phenyl-p-phenylenediamine, 0.8-1.2 parts of a vulcanizing agent, 2-5 parts of a catalyst, and 3-5 parts of an accelerator.

2. The fatigue-resistant modified natural rubber material according to claim 1, characterized in that: The halogenated polyolefin is one or more of chlorinated chloroprene rubber, chlorinated natural rubber, brominated EPDM rubber or brominated natural rubber.

3. The fatigue-resistant modified natural rubber material according to claim 2, characterized in that: The average molecular weight of the halogenated polyolefin is 100,000 to 300,000.

4. The fatigue-resistant modified natural rubber material according to claim 1, characterized in that: The weight ratio of the 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine to N-isopropyl-N'-phenyl-p-phenylenediamine is 2:

1.

5. The fatigue-resistant modified natural rubber material according to claim 1, characterized in that: The catalyst is one of tetramethylammonium hydroxide and alkyl lithium.

6. The fatigue-resistant modified natural rubber material according to claim 1, characterized in that: The vulcanizing agent is one or more of sulfur, vulcanizing agent S, TMTD, TMRR, TRTD, DTDM, BPO, DCP and DTBP.

7. The fatigue-resistant modified natural rubber material according to claim 1, characterized in that: The vulcanizing agent is, and the accelerator is one or more of accelerator DETU, accelerator DPG, accelerator BZ, accelerator PZ, accelerator ZDC and accelerator CZ.

8. A method for preparing the fatigue-resistant modified natural rubber material according to any one of claims 1 to 7, characterized in that: The preparation steps are as follows: S1. Under nitrogen protection, chlorinated natural rubber is added to natural rubber latex for refining. After uniform refining, the mixture is divided into two parts. 2,4,6-tris[N-(1,4-dimethylpentyl)-p-phenylenediamino]-1,3,5-triazine is added to one part to form component A, and N-isopropyl-N'-phenyl-p-phenylenediamine is added to the other part to form component B. S2. First, a catalyst is added to component A and refined evenly, then component A and component B are mixed and refined, and then a promoter is added and refined to obtain a multi-component copolymer product E; S3. First, mix the super wear-resistant furnace black filler and zinc oxide evenly, then add them to the multi-polymer product E and mix them first, then let them stand and cure for 12 hours, then add the vulcanizing agent, and perform vulcanization treatment in a vulcanizer to obtain a fatigue-resistant modified natural rubber material.

9. The method for preparing the fatigue-resistant modified natural rubber material according to claim 8, characterized in that: In step S2, the mixing and refining time of components A and B is 24-36 hours, and the refining time of adding the accelerator is 22-26 hours.

10. The method for preparing the fatigue-resistant modified natural rubber material according to claim 8, characterized in that: In step S3, the mixing time of the multi-element tool product E is 36-48 hours, and the vulcanization time is 42-48 hours.

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