Modified natural rubber and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to modified natural rubber and a preparation method thereof.The preparation method comprises the steps that S1, in the inert gas atmosphere, rubber and a dopamine solution are mixed and react to form a rubber system containing dopamine; s2, adding a ferric salt solution (such as a ferric chloride solution) into the rubber system containing the dopamine, stirring, gradually condensing and separating out, then washing with distilled water, and drying, so as to obtain the self-repairing modified natural rubber; the technical process is simple, preparation is easy, in the preparation process, dopamine is introduced, free iron elements are added into a system, reversible metal complex bonds are formed through the iron elements and dopamine molecules, and therefore when rubber is damaged, the iron elements and hydrogen bonds between rubber macromolecules act together, a synergistic self-repairing mechanism is formed, and the self-repairing performance of the rubber is improved. The self-repairing of the rubber material is realized, and the application requirements are better met.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly to a modified natural rubber and a preparation method thereof. Background Art

[0002] Rubber materials are widely used in various industrial fields due to their excellent elasticity, wear resistance and sealing performance. However, rubber is prone to damage due to external forces or environmental factors during use, affecting its service life and performance. Self-healing rubber is a rubber material with self-healing ability, which can automatically restore its original structure and performance after being damaged. At present, the research on self-healing rubber has become a hot spot in the field of materials science.

[0003] The present invention aims to introduce specific groups and components through chemical modification methods to achieve the self-healing function of rubber materials and enhance their adhesion to metal materials such as steel, so as to better meet the application requirements. Summary of the Invention

[0004] To solve the above problems, the present invention provides a modified natural rubber and a preparation method thereof. By grafting maleic anhydride modification to introduce polar groups, the hydrogen bond interaction between rubber macromolecules is enhanced. Combining the introduction of dopamine to enhance the adhesion to steel materials, and at the same time using the reversible complexation of free iron elements and dopamine to construct a self-healing mechanism synergistic with hydrogen bonds and reversible metal complex bonds, significantly improving the self-healing performance of rubber materials.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A preparation method of a modified natural rubber, comprising the following steps:

[0007] S1. In an inert gas atmosphere, mix rubber with a dopamine solution and react to form a rubber system containing dopamine;

[0008] S2. Add an iron salt solution (such as ferric chloride solution) to the rubber system containing dopamine, stir and gradually precipitate, and then rinse and dry with distilled water to obtain self-healing modified natural rubber.

[0009] Further, in step S1, the rubber is epoxidized natural rubber latex.

[0010] Further, the preparation steps of the epoxidized natural rubber latex are as follows:

[0011] Add a surfactant to high ammonia concentrated natural rubber latex, then stir to evaporate all the ammonia water therein, and then slowly drop formic acid and hydrogen peroxide, and react at 10-30 °C to obtain epoxidized natural rubber latex.

[0012] Further, in the step of preparing the epoxidized natural rubber latex: after dropping formic acid and hydrogen peroxide, react it in a water bath at 10-30°C, measure the temperature of the latex every hour, and stop the reaction at different times to obtain epoxidized natural rubber latex with different epoxide degrees.

[0013] Further, in the step of preparing the epoxidized natural rubber latex, by mass, in 100 parts of high-ammonia concentrated natural rubber latex with a solid content of 30%, add 1-2 parts of surfactant; in 100 parts of high-ammonia concentrated natural rubber latex with a solid content of 30%, dropwise add 8-12 parts of formic acid and 10-25 parts of hydrogen peroxide.

[0014] Further, the surfactant is OP-10 、 Any several of nonylphenol polyoxyethylene ether and nonylphenol polyoxyethylene ether.

[0015] Further, by mass, add 10 parts of dopamine to 100 parts of base rubber, react, and then add 3-10 parts of iron salt solution.

[0016] Further, in step S1, the reaction conditions are water bath stirring reaction, the water bath temperature is 30-40°C, and the reaction time is 5-7 hours.

[0017] Based on the same inventive concept, the present application also provides a modified natural rubber prepared according to the above preparation method.

[0018] The beneficial effects of the present invention are as follows:

[0019] The preparation method provided by the present invention includes step S1. In an inert gas atmosphere, mix rubber with dopamine solution to react to form a rubber system containing dopamine; S2. Add an iron salt solution (such as ferric chloride solution) to the rubber system containing dopamine, stir and gradually precipitate and coagulate, and then rinse and dry with distilled water to obtain self-healing modified natural rubber; its process flow is simple and easy to prepare. During the preparation process, by introducing dopamine, using the adhesiveness of dopamine and its special interaction with the metal surface, the adhesion between rubber and metal materials such as steel is significantly enhanced. Moreover, the phenolic hydroxyl group and amino group in the dopamine molecule provide metal complexing characteristics. At the same time, by adding an iron salt solution to the system to add free iron elements to the rubber system, a reversible metal complexing bond is formed between the iron element and the dopamine molecule, so as to act together with the hydrogen bond between the rubber macromolecules when the rubber is damaged, forming a synergistic self-healing mechanism to achieve the self-healing of the rubber material and better meet the application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flowchart of the preparation process in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] For the convenience of understanding the present invention, the present invention will be described more comprehensively below through embodiments, and the preferred embodiments of the present invention are given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. All other implementation schemes obtained by modifying the technical solution of the present invention or making equivalent substitutions without creative results are within the protection scope of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field of the present invention. The terms used in the specification of the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0023] The numerical values disclosed in the embodiments of the present invention are approximate values and not definite values. Within the allowable range of errors or experimental conditions, all values within the error range can be included and are not limited to the specific numerical values disclosed in the embodiments of the present invention.

[0024] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or can be prepared by existing methods.

[0025] See Figure 1 As shown, the preparation method of the modified natural rubber provided by the present application includes the following steps:

[0026] S1. In a nitrogen atmosphere, mix the rubber with a dopamine solution and react to form a rubber system containing dopamine;

[0027] S2. Add an iron salt solution (such as ferric chloride solution) to the rubber system containing dopamine, stir and gradually coagulate and precipitate, and then rinse and dry with distilled water to obtain self-healing modified natural rubber.

[0028] For the preparation method provided by the present application, the specific synthesis route in step S1 is as follows:

[0029]

[0030] After introducing iron elements in step S2, the structural formula of the finally prepared self-healing modified natural rubber is as follows:

[0031]

[0032] The following are specific embodiments

[0033] Example 1

[0034] This embodiment provides a preparation method of modified natural rubber, including the following steps:

[0035] First, add high-ammonia concentrated natural rubber latex with a solid content of 60% to water and dilute its solid content to 30%.

[0036] Take 100 parts of the diluted high-ammonia concentrated natural rubber latex, add 1.5 parts of OP-10 surfactant, stir for 30 minutes to completely evaporate the ammonia water and make the surfactant evenly mixed. Then, slowly dropwise add 11 parts of formic acid and 15 parts of hydrogen peroxide in sequence, and let them react in a water bath at a temperature of 20°C. Measure the temperature of the latex every hour during the reaction. Stop the reaction after 2 hours to obtain epoxidized natural rubber latex.

[0037] In a nitrogen atmosphere, add 10 parts of dopamine to 100 parts of the above epoxidized natural rubber latex, and carry out a water bath stirring reaction at a temperature of 35°C for 6 hours.

[0038] Then add 3.5 parts of ferric chloride, stir and gradually coagulate and precipitate. After that, rinse with distilled water and dry to obtain self-healing modified natural rubber.

[0039] Example 2

[0040] This example provides a method for preparing modified natural rubber, including the following steps:

[0041] First, add high-ammonia concentrated natural rubber latex with a solid content of 60% to water and dilute its solid content to 30%.

[0042] Take 100 parts of the diluted high-ammonia concentrated natural rubber latex, add 1.5 parts of OP-10 surfactant, stir for 30 minutes to completely evaporate the ammonia water and make the surfactant evenly mixed. Then, slowly dropwise add 11 parts of formic acid and 15 parts of hydrogen peroxide in sequence, and let them react in a water bath at a temperature of 20°C. Measure the temperature of the latex every hour during the reaction. Stop the reaction after 6 hours to obtain epoxidized natural rubber latex.

[0043] In a nitrogen atmosphere, add 20 parts of dopamine to 100 parts of the above epoxidized natural rubber latex, and carry out a water bath stirring reaction at a temperature of 35°C for 6 hours.

[0044] Then add 7 parts of ferric chloride, stir and gradually coagulate and precipitate. After that, rinse with distilled water and dry to obtain self-healing modified natural rubber.

[0045] Example 3

[0046] This example provides a method for preparing modified natural rubber, including the following steps:

[0047] First, add high-ammonia concentrated natural rubber latex with a solid content of 60% to water and dilute its solid content to 30%.

[0048] Take 100 parts of diluted high-ammonia concentrated natural rubber latex, add 1.5 parts of OP-10 surfactant, stir for 30 minutes to completely evaporate the ammonia water and make the surfactant evenly mixed. Then, slowly drop 11 parts of formic acid and 15 parts of hydrogen peroxide successively, and let them react in a water bath at a temperature of 20°C. Measure the temperature of the latex every hour during the reaction. Stop the reaction after 12 hours to obtain epoxidized natural rubber latex.

[0049] In a nitrogen atmosphere, add 25 parts of dopamine to 100 parts of the above epoxidized natural rubber latex, and carry out a water bath stirring reaction at a temperature of 35°C for 6 hours.

[0050] Add 9 parts of ferric chloride, stir and gradually coagulate and precipitate, and then rinse and dry with distilled water to obtain self-healing modified natural rubber.

[0051] Prepare the self-healing modified natural rubber prepared in Examples 1-3 above into composite self-healing rubber respectively for performance testing.

[0052] Among them, the mechanical properties of the self-healing rubber are tested according to the national standard GB / T 528-2009; the self-healing efficiency test method is as follows: after cutting off the rubber tensile test sample, align the fracture and splice it, and let it stand for 48 hours at a temperature of 25°C, and then test the tensile strength according to GB / T 528-2009. The repair efficiency is

[0053] y 修复效率 =T 修复后拉伸强度 / T 破坏前橡胶拉伸性能 *100%.

[0054] Specifically, taking 100 parts by mass of the self-healing modified natural rubber prepared in Example 1, compound it with 4 parts of zinc oxide, 1.5 parts of stearic acid, 2 parts of antioxidant 4020, 25 parts of reinforcing carbon black, 5 parts of plasticizer paraffin oil, 2 parts of accelerator CZ and 1 part of sulfur, and form it through a mixer, an open mill and a flat vulcanizer to make a self-healing composite rubber.

[0055] After testing, the tensile strength of this self-healing composite rubber is 17.1 MPa, the elongation at break is 420%, the tear strength is 45 N / mm, the tensile strength after shearing is 13.4 MPa, and the self-healing efficiency is 78.3%.

[0056] Specifically, taking 100 parts by mass of the self-healing modified natural rubber prepared in Example 2, compound it with 5 parts of zinc oxide, 1 part of stearic acid, 2 parts of antioxidant 4010, 20 parts of reinforcing carbon black, 10 parts of plasticizer paraffin oil, 2 parts of accelerator BZ and 1 part of sulfur, and form it through a mixer, an open mill and a flat vulcanizer to make a self-healing composite rubber.

[0057] After testing, the tensile strength of the self-healing composite rubber is 13.2 MPa, the elongation at break is 550%, the tear strength is 30 N / mm, the tensile strength after shearing is 11.4 MPa, and the self-healing efficiency is 86.3%.

[0058] Specifically, taking 100 parts by mass of the self-healing modified natural rubber prepared in Example 3, compounding it with 3 parts of zinc oxide, 1 part of stearic acid, 2 parts of RD antioxidant, 25 parts of silica, 5 parts of plasticizer paraffin oil, 2 parts of CZ accelerator, and 0.5 part of sulfur, and molding it through a mixer, an open mill, and a flat vulcanizer to make the self-healing composite rubber.

[0059] After testing, the tensile strength of the self-healing composite rubber is 14.6 MPa, the elongation at break is 500%, the tear strength is 35 N / mm, the tensile strength after shearing is 12.9 MPa, and the self-healing efficiency is 88.3%.

[0060] In summary, the preparation method of the self-healing modified natural rubber provided by this application has a simple process flow and is easy to prepare. During the preparation process, by introducing dopamine, using the adhesiveness of dopamine and its special interaction with the metal surface, the adhesion between the rubber and metal materials such as steel is significantly enhanced. Moreover, the phenolic hydroxyl group and amino group in the dopamine molecule provide metal complexation characteristics. At the same time, by adding an iron salt solution to the system to add free iron elements to the rubber system, a reversible metal complex bond is formed between the iron element and the dopamine molecule, so that when the rubber is damaged, it acts together with the hydrogen bond between the rubber macromolecules to form a synergistic self-healing mechanism, realizing the self-repair of the rubber material and better meeting the application requirements.

[0061] Specifically referring to the examples of this application, the self-healing modified natural rubber prepared by the preparation method of this application is compounded into a composite self-healing rubber, which shows more excellent performance in terms of tensile strength, elongation at break, tear strength, tensile strength after shearing, and self-healing efficiency. It has a high tensile strength and can withstand greater loads; it has a large elongation at break and good flexibility, and can adapt to more complex deformation conditions; it has a high tear strength and strong resistance to damage; it has a high retention rate of tensile strength after shearing and strong mechanical property recovery ability; it has a high self-healing efficiency and can quickly self-repair, extending the service life. These excellent performance points enable the self-healing composite rubber to better meet the application requirements in application scenarios that require high reliability and long life.

[0062] The above-described embodiments merely represent several implementation manners of the present invention. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention shall be subject to the appended claims.

Claims

1. A method for preparing modified natural rubber, characterized in that: The steps include: S1. In an inert gas atmosphere, mixing the rubber with the dopamine solution to react and form a rubber system containing dopamine; S2. Add an iron salt solution to the rubber system containing dopamine, stir and gradually condense and precipitate, then rinse with distilled water and dry to obtain a self-healing modified natural rubber.

2. The method for preparing modified natural rubber according to claim 1, characterized in that: In step S1, the rubber is epoxidized natural rubber latex.

3. The method for preparing modified natural rubber according to claim 2, characterized in that: The preparation steps of the epoxidized natural rubber latex are as follows: A surfactant is added to the high-ammonia concentrated natural rubber latex, and then stirred to evaporate the ammonia water therein, and then formic acid and hydrogen peroxide are slowly added dropwise to react at 10-30°C to obtain epoxidized natural rubber latex.

4. The method for preparing modified natural rubber according to claim 3, characterized in that: In the step of preparing epoxidized natural rubber latex: after adding formic acid and hydrogen peroxide dropwise, the latex is reacted in a water bath at 10-30° C., and the temperature of the latex is measured every hour.

5. The method for preparing modified natural rubber according to claim 3, characterized in that: In the step of preparing epoxidized natural rubber latex, 1 to 2 parts of surfactant are added to 100 parts of high ammonia concentrated natural latex with a solid content of 30% by mass; 8 to 12 parts of formic acid and 10 to 25 parts of hydrogen peroxide are added dropwise to 100 parts of high ammonia concentrated natural latex with a solid content of 30%.

6. The method for preparing modified natural rubber according to claim 3, characterized in that: The surfactant is OP-10 、 Any of nonylphenol polyoxyethylene ether and nonylphenol polyoxyethylene ether.

7. The method for preparing modified natural rubber according to claim 3, characterized in that: According to the mass percentage, dopamine is added to 100 parts of the base rubber for reaction, and then 3-10 parts of the iron salt solution are added.

8. The method for preparing modified natural rubber according to claim 1, characterized in that: In step S1, the reaction conditions are stirring reaction in a water bath, the water bath temperature is 30-40° C., and the reaction time is 5-7 hours.

9. A modified natural rubber prepared according to the preparation method according to any one of claims 1 to 8.

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