Method for testing aging performance of base glue

Abstract

The invention provides a method for testing the aging performance of base rubber, which comprises the following steps of: preparing the base rubber into a test piece, vulcanizing and statically aging the test piece in an anaerobic state, and then testing the aging coefficient of the aged test piece. According to the method, the base rubber is vulcanized and aged in an anaerobic state, and the environment of the base rubber in the tire is highly reduced and simulated, so that the result of the test method disclosed by the invention is beneficial to reducing the real condition of the aging performance of the base rubber.

Description

Technical Field

[0001] The present invention relates to the technical field of base rubber, and specifically relates to a method for testing the aging performance of base rubber. Background Art

[0002] A tire is an organic nanocomposite with unsaturated rubber as the main body. Due to the presence of its unsaturated double bonds, its performance will be lost or even fail due to thermal oxygen and ozone aging during use; therefore, antioxidants are generally filled in the tire formula to ensure the aging resistance of the tire. The currently commonly used antioxidant models are 4020, RD, and 3100. Among them, 4020 and 3100 are both p-phenylenediamine antioxidants. Although the existing antioxidant products have relatively significant effects in anti-aging in the fields of tires and the like, the evaluation of the aging performance of rubber compounds in the laboratory is under high-temperature aerobic conditions. This method has a relatively high reduction degree for the aging performance evaluation of rubber compounds that are in long-term contact with air, such as tread rubber or sidewall rubber; however, for base rubber, cushion rubber, and triangle rubber, from vulcanization to being put on the road for use, they have been in an anaerobic state, and heat damage to the aging performance dominates, while oxygen loss only accounts for a very small part. Therefore, when conducting aging performance testing in the laboratory, it should be tested under anaerobic and high-temperature conditions.

[0003] However, the current test method for systematically analyzing the aging performance of base rubber in the laboratory is vulcanization and aging. This aging performance test carried out in an aerobic environment cannot truly simulate the aging state of base rubber. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to restore the test method for the aging performance of base rubber.

[0005] The present invention solves the above technical problem by the following technical means:

[0006] The present invention provides a method for testing the aging performance of base rubber, making the base rubber into test pieces, vulcanizing and statically aging the test pieces in an anaerobic state, and then testing the aging coefficient of the aged test pieces.

[0007] Beneficial Effects: The present invention vulcanizes and ages the base rubber in an anaerobic state, highly restoring and simulating the environment of the base rubber in the tire. Therefore, the results of the test method of the present invention help to restore the true situation of the aging performance of the base rubber.

[0008] Preferably, the vulcanization conditions are film vulcanization at 150°C for 35 minutes, and standing for 12 hours after vulcanization.

[0009] Preferably, the temperature of static aging is 100 - 120°C, and the time of static aging is 24 - 96 hours.

[0010] Preferably, the specific conditions for static aging are one of 100°C * 48h, 100°C * 72h, 100°C * 96h, 120°C * 24h, 120°C * 48h, or 120°C * 72h.

[0011] Preferably, the test pieces after aging are left standing for 4h and then the aging coefficient is measured.

[0012] Preferably, the formula for the aging coefficient is as follows:

[0013] Wherein, A is the aging coefficient, TS is the tensile strength, with the unit of Mpa, EB is the elongation at break, %.

[0014] TS’ is the tensile strength after aging, with the unit of Mpa, EB’ is the elongation at break after aging, %.

[0015] Preferably, the base rubber is made into test pieces by passing through rolls on an open mill.

[0016] Preferably, the temperature of the open mill is 58 - 62°C.

[0017] Preferably, the thickness of the test pieces is 1.2 - 1.4mm.

[0018] Preferably, the test pieces are obtained in an anaerobic state by wrapping them with glassine paper to squeeze out the air.

[0019] Beneficial effects: By simply coating the test pieces made of glassine paper base rubber, the present invention enables vulcanization and aging in an anaerobic state, which can accurately detect the loss of the base rubber at high temperatures in an anaerobic state. The operation of the present invention is simple; the present invention provides a new idea to test the aging performance of the base rubber in the laboratory. Only through simple coating, it highly restores and simulates the environment of the base rubber in the tire, and its test results restore the true situation of the aging performance of the base rubber. Specific Embodiments

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] The test materials and reagents used in the following embodiments can be obtained from commercial channels without special instructions.

[0022] For those without specific technologies or conditions noted in the examples, they can all be carried out according to the technologies or conditions described in the literature in this field or according to the product instructions.

[0023] Example 1

[0024] This example provides a method for testing the aging performance of base rubber, which specifically includes the following steps:

[0025] The base rubber is passed through a two-roll mill at 60 °C to make test pieces. In this example, 4 test pieces are prepared. The thickness of the test pieces is 1.2 mm. Then, the upper and lower sides of the test pieces are wrapped with glassine paper to squeeze out air, so that the test pieces are vulcanized on a flat vulcanizer in an oxygen-free state. The vulcanization conditions are film vulcanization at 150 °C for 35 min, and after vulcanization, they are left standing for 12 h; 1 test piece is cut to obtain a sample for testing, and the tensile strength, elongation at break, and modulus at a specified elongation before aging are tested.

[0026] The 3 vulcanized test pieces are put into an aging oven for aging. The aging conditions of the 3 test pieces are 100 °C * 48 h, 100 °C * 72 h, and 120 °C * 24 h respectively. After aging, the test pieces are left standing for 4 h. Then, the glassine paper on the surface of the test pieces is removed, and the test pieces are cut to obtain samples for testing. The tensile strength, elongation at break, and modulus at a specified elongation after aging are tested. The results of the aging coefficient are shown in Table 1.

[0027] Example 2

[0028] This example provides a base rubber and a method for testing the aging performance of the base rubber, specifically as follows:

[0029] S1 The base rubber comprises the following raw materials in parts by weight:

[0030] 100 parts of natural rubber, 30 parts of carbon black N330, 10 parts of white carbon black, 10 parts of pyrolytic carbon black, 3 parts of solid silane, 1.5 parts of antioxidant 4020, 1 part of antioxidant 4010NA, 1 part of antioxidant RD, 3 parts of zinc oxide, 2 parts of stearic acid, 1 part of paraffin wax, 1.5 parts of sulfur, 1 part of accelerator NS, 0.1 part of scorch retarder CTP.

[0031] S2 Preparation of the base rubber

[0032] (1) 100 parts of natural rubber, 20 parts of carbon black N330, 5 parts of white carbon black, all the antioxidants and 3 parts of solid silane are added to a small internal mixer for mixing. The rotor speed of the internal mixer is 90 rpm, the mixing time is 40 s, and the upper plug pressure is 5.0 N / cm 2; When the temperature in the internal mixer reaches 120°C, add the remaining 10 parts of carbon black, 5 parts of silica, 10 parts of pyrolytic carbon black, 3 parts of zinc oxide, 2 parts of stearic acid and 1 part of paraffin wax for mixing. When the temperature in the internal mixer reaches 130°C, lift the upper ram, hold for 10 s, and then lower the upper ram; when the temperature of the internal mixer reaches 160°C, discharge the rubber to obtain the mixed rubber;

[0033] (2) Mix the mixed rubber with 1.5 parts of sulfur, 1 part of accelerator TBBS and 0.1 part of scorch retarder CTB on an open mill, and obtain the base rubber by passing through the rolls.

[0034] S3 Method for testing the aging performance of the base rubber. The method for testing the aging performance of the base rubber in this example is exactly the same as that in Example 1, and will not be specifically described here. The aging coefficient is shown in Table 2.

[0035] Comparative Example 1

[0036] This comparative example provides a method for testing the aging performance of the base rubber. Compared with Example 1, the difference is that the test piece is vulcanized and aged in an aerobic state, and the others are the same. The aging coefficient is shown in Table 1.

[0037] Comparative Example 2

[0038] This comparative example provides a method for testing the aging performance of the base rubber. Compared with Example 1, the difference is that the test piece is vulcanized in an aerobic state and aged in an anaerobic state, and the others are the same. The aging coefficient is shown in Table 1.

[0039] Comparative Example 3

[0040] This comparative example provides a method for testing the aging performance of the base rubber. Compared with Example 2, the difference is that the test piece is vulcanized and aged in an aerobic state, and the others are the same. The aging coefficient is shown in Table 2.

[0041] Comparative Example 4

[0042] This comparative example provides a method for testing the aging performance of the base rubber. Compared with Example 2, the difference is that the test piece is vulcanized in an aerobic state and aged in an anaerobic state, and the others are the same. The aging coefficient is shown in Table 2.

[0043] The test results of the aging performance of the base rubber in Example 1 and Comparative Examples 1-2 are shown in Table 1.

[0044] Table 1

[0045]

[0046] The test results of the aging performance of the base rubber in Example 2 and Comparative Examples 3-4 are shown in Table 2.

[0047] Table 2

[0048]

[0049]

[0050] The free radical chain reaction mechanism of the base rubber oxidation reaction was proposed based on the oxidation research of simulated compounds of high polymers such as rubber. The whole reaction is divided into three stages: initiation, propagation, and termination.

[0051] 1. Chain initiation: After the rubber macromolecule RH in the base rubber is affected by heat or oxygen, macromolecular free radicals R· are generated at the weak points of the molecular structure. The specific reaction is as follows:

[0052] RH → R· + ·H (1)

[0053] 2. Chain propagation: Under the action of oxygen, the free radical R· is auto-oxidized to generate a peroxy free radical ROO·. The free radical ROO· continues to react to generate a macromolecular hydroperoxide ROOH, and ROOH will decompose into free radicals R·. The specific reactions are as follows:

[0054] R·+ O2 → ROO· (2)

[0055] ROO· + RH → ROOH + R· (3)

[0056] ROOH → RO· + OH· (4)

[0057] 2ROOH → RO· + ROO· + H2O (5)

[0058] RO· + RH → ROH + R· (6)

[0059] ROO· + RH → ROOH + R· (7)

[0060] ·OH + RH → R· + H2O (8)

[0061] 3. Chain termination: The macromolecular chain free radicals combine with each other to form inert molecules, terminating the chain reaction. The specific reactions are as follows:

[0062] R· + R· → R-R (9)

[0063] R· + RO· → ROR (10)

[0064] R·+ ROO· → ROOR (11)

[0065] ROO· + ROO· → Non-radical products (12)

[0066] It can be seen from the data in Table 1 and Table 2 that there are significant differences in the base rubber aging performance test results between Examples 1-2 and Comparative Examples 1-4. During the base rubber aging performance test of the examples, the base rubber was in an anaerobic state throughout the process, and the aging rate of the base rubber was the slowest. Moreover, under ultra-long-term high temperature, the attenuation of the base rubber aging performance was slower. This is because in the absence of the action of oxygen, the combination process of polymer free radicals and oxygen is slower. According to the above oxidation reaction principle, in the chain initiation stage, the rubber macromolecule RH in the base rubber is inhibited from oxidation in the anaerobic state, and at this time, it is mainly thermal aging, so there are only a small amount of free radicals R·. In the subsequent chain transfer stage, the combination of free radicals R· and oxygen is also greatly inhibited. This reaction process is completely different from the base rubber aging performance test methods of Comparative Examples 1 and 3. Because in this example, an anaerobic state is constructed during the vulcanization process and the aging process, highly reducing and simulating the environment of the base rubber in the tire, so it is more suitable for studying the aging process of the tire base rubber.

[0067] The above examples are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing examples, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for testing the aging performance of base glue, characterized in that, The base rubber is made into test pieces, and the test pieces are vulcanized and statically aged under an anaerobic state, and then the aging coefficient of the aged test pieces is tested.

2. The base glue aging performance testing method according to claim 1, characterized in that The vulcanization conditions are compression molding vulcanization at 150 °C for 35 min, and standing for 12 h after vulcanization.

3. The base glue aging performance test method according to claim 1, characterized in that The temperature of static aging is 100 - 120 °C, and the time of static aging is 24 - 96 h.

4. The base glue aging performance testing method according to claim 1 or 3, characterized in that, The specific conditions of static aging are one of 100 °C * 48 h, 100 °C * 72 h, 100 °C * 96 h, 120 °C * 24 h, 120 °C * 48 h or 120 °C * 72 h.

5. The base glue aging performance test method according to claim 4, characterized in that, The aged test pieces are left standing for 4 h and then the aging coefficient is tested.

6. The base glue aging performance test method according to claim 1 or 5, characterized in that, The formula for the aging coefficient is as follows: Among them, A is the aging coefficient, TS is the tensile strength, with the unit of Mpa, EB is the elongation at break, %, TS’ is the tensile strength after aging, with the unit of Mpa, EB’ is the elongation at break after aging, %.

7. The base glue aging performance testing method according to claim 1, wherein The base rubber is made into test pieces by passing through the rolls of an open mill.

8. The base glue aging performance testing method according to claim 7, characterized in that The temperature of the open mill is 58 - 62 °C.

9. The method for testing the aging performance of the base glue according to claim 7, wherein The thickness of the test piece is 1.2 - 1.4 mm.

10. The method for testing the aging performance of the base glue according to claim 1, wherein The test pieces are obtained under an anaerobic state by the following method: the test pieces are wrapped with glass paper to squeeze out the air.

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