Method for evaluating chromatic aberration of rubber composite material

Abstract

The invention relates to the technical field of material detection, and particularly discloses a rubber composite material color difference evaluation method, which is used for solving the problem of inconvenient detection in the prior art. Comprising the following steps: 1, sample preparation: selecting two or more different rubber composite materials, and preparing a sample with a flat and smooth cross section; step 2, chromaticity testing: using a precision colorimeter, using the test data of the standard plate as a reference, performing chromaticity testing on the cross sections of different rubber composite material samples, and recording the measured data values of the samples; and step 3, analyzing data: analyzing the chromaticity data of the test samples to obtain a color difference value E. According to the method, subjective factors of people are eliminated to a certain extent, and a judgment basis is provided by selecting a low-color-difference formula in the tire tread. In addition, the chromatic aberration of the same sample in different periods can be represented by using a precise colorimeter, and the influence of the precipitation process of small molecular substances in the rubber on the appearance of the rubber material can be observed.

Description

Technical Field

[0001] The invention relates to the technical field of material detection, in particular to a method for evaluating color difference of a rubber composite material. Background Art

[0002] With the increasing sales of automobiles, more stringent requirements are put forward for the performance of automobile tires. In order to take into account the grip and rolling resistance of tires at the same time, two rubber composite materials are often used in the design of tire treads. The upper tread has a higher slip index to provide high grip for the tire, and the lower tread has a lower calorific value to reduce the rolling resistance of the tire. Due to the different types, quantities and mixing processes of fillers in the upper and lower tread formulas, there is a color difference between the upper and lower treads. Color spots appear during tire wear. In addition, during the use of the tire, the small molecular organic materials with color in the rubber will migrate to the surface of the tire, forming red, blue and white spots, which seriously affect the appearance quality of the tire.

[0003] Traditional methods for evaluating the color difference of rubber composite materials in tires mainly include subjective evaluation method and stereo microscope method. The subjective evaluation method uses human vision to evaluate the color difference of rubber samples. The stereo microscope method is to prepare different rubber materials into the same sample, take photos with a microscope, and then conduct subjective evaluation. Since the human eye has limited sensitivity to color, if the color difference between rubber materials is small, it is difficult for the human eye to distinguish, and the evaluation results vary from person to person. The stereo microscope method is greatly affected by the intensity and direction of the light source of the stereo microscope, and it is difficult to prepare tire samples. The judgment results are also affected by people's subjective evaluation of the photos.

[0004] Based on this, a method for evaluating color difference of rubber composite materials is now provided, which can eliminate the disadvantages of existing devices. Summary of the invention

[0005] The purpose of the present invention is to provide a method for evaluating color difference of a rubber composite material, which solves the problem of inconvenient detection in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for evaluating color difference of a rubber composite material comprises the following steps:

[0008] Step 1: Sample preparation: Select two or more different rubber composite materials and prepare samples with smooth cross-sections;

[0009] Step 2: Chroma test: Use a precision colorimeter and standard plate test data as a benchmark to perform chroma tests on cross sections of different rubber composite samples and record the sample measurement data values;

[0010] Step 3: Analyze data: Analyze the chromaticity data of the test samples to obtain the color difference value △E between each sample.

[0011] On the basis of the above technical solution, the present invention also provides the following optional technical solution:

[0012] In an optional solution: the colorimeter is a precision colorimeter capable of performing one or more of Lab, RGB, and XYZ colorimetric mode measurements.

[0013] In an optional solution, the test sample is one or both of a vulcanized rubber composite material and an unvulcanized rubber composite material.

[0014] In an optional solution, the vulcanized rubber composite material may be vulcanized by one or more of sulfur vulcanization, metal oxide vulcanization, resin vulcanization, peroxide vulcanization, and thiuram vulcanization.

[0015] In an optional solution: the specific analysis in step 3 is:

[0016] Then, the cross sections of sample 1 and sample 2 were tested for Lab chromaticity values ​​three times and recorded as L1, a1, b1, L2, a2, b2 respectively.

[0017] In an optional solution: the cylindrical specimen of the test sample is cut into a fresh cross section, and the diameter and thickness of the circular cross section remain uniform.

[0018] In an optional solution: the cross sections of the samples 1 and 2 are subjected to three Lab chromaticity value tests and the three average values ​​are taken as the benchmark data.

[0019] In an optional solution: after cutting the fresh cross section in step 2, take photos and observe under the same light source intensity and direction under a stereo microscope.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This proposal develops a method for measuring and evaluating the color difference of rubber compounds using a precision colorimeter. This method has simple sample preparation, high test stability, and small measurement error. It eliminates human subjective factors to a certain extent and provides a basis for judgment when selecting low color difference formulas in tire treads. In addition, the precision colorimeter can be used to characterize the color difference of the same sample at different times and observe the effect of the precipitation process of small molecular substances in rubber on the appearance of the rubber compound. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a photographic observation diagram taken under the same light source intensity and light source direction under the microscope of Example 1 of the present invention.

[0023] Figure 2 This is a comparison diagram of two tires in Example 2. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In order to overcome the shortcomings of the prior art, the present invention provides a method for evaluating the color difference of a rubber composite material using a precision colorimeter, by measuring the surface color of the rubber composite material and performing color difference evaluation based on colorimetric data analysis. The specific technical solution is as follows:

[0026] 1) Sample preparation: Select two or more different rubber composite materials and use a sharp tool to prepare samples with smooth cross-sections.

[0027] 2) Chroma test: Turn on the colorimeter, calibrate the colorimeter, use the standard plate test data as a benchmark, perform chroma tests on the cross sections of different rubber composite samples, and record the sample measurement data values.

[0028] 3) Analyze data: Take the average value of the chromaticity data of the test samples for analysis and obtain the color difference value △E between each sample.

[0029] Further:

[0030] In step 1), the sample may be one or more of an unvulcanized rubber composite material and a vulcanized rubber composite material. The diameter of the cross-sectional area of ​​the sample is greater than 1 cm, and the thickness is greater than 0.5 mm. In order to avoid the precipitation of small molecules affecting the appearance, a fresh cross-section of the sample should be used in the colorimetric test.

[0031] In the step 2), the colorimeter is a precision colorimeter, the color of the standard plate is black, white, blue or any other color, and the sample is tested for chromaticity three times to obtain an average value, including one or more of the Lab, RGB, and XYZ chromaticity test modes.

[0032] In the step 3), the Lab average data of the chromaticity of different test samples are analyzed, and the chromaticity values ​​of the standard plate are set to L0, a0, and b0, the chromaticity test values ​​of the test sample 1 are L1, a1, and b1, and the chromaticity test values ​​of the test sample 2 are L2, a2, and b2. Then the color difference between sample 1 and sample 2 is

[0033] In step 3), the RGB value average data of the chromaticity of different test samples are analyzed, and the chromaticity values ​​of the standard plate are set to R0, G0, and B0, the chromaticity test values ​​of test sample 1 are R1, G1, and B1, and the chromaticity test values ​​of test sample 2 are R2, G2, and B2. Then the color difference value between sample 1 and sample 2 is

[0034] In step 3), the XYZ average data of the chromaticity of different test samples are analyzed, and the chromaticity values ​​of the standard plate are set to X0, Y0, and Z0, the chromaticity test values ​​of test sample 1 are X1, Y1, and Z1, and the chromaticity test values ​​of test sample 2 are X2, Y2, and Z2. Then the color difference between sample 1 and sample 2 is

[0035] The precision colorimeter used in the present invention is available in the market and is simple and quick to operate. It can provide a fast and accurate color difference comparison method for rubber composite material scientific research personnel, and provide a basis for the formulation design of rubber composite materials and the use direction of composite materials.

[0036] Embodiment 1:

[0037] The following examples further illustrate the present invention, but should not be construed as limiting the present invention;

[0038] A rubber composition having the components specified in Table 1 was prepared in a rubber internal mixer for non-productive stage mixing. The mixing method adopted was a common mixing method adopted by tire companies. The resulting mixture was recovered and cooled, and then sulfur and an accelerator were added to an external mixer for mixing. A cylindrical sample with a diameter of 2 cm and a height of 3 cm was prepared by calendering in the form of a sheet, and vulcanized at 150° C. for 30 minutes to complete the preparation of a vulcanized rubber composite material.

[0039] The rubber composite materials of different schemes are referred to herein as Sample 1, Sample 2, and Sample 3. With rubber as 100 parts, other materials are expressed in weight percentage of rubber, with the symbol phr, which is a common tread rubber composition and is not used in the present invention;

[0040] Material Sample 1 Sample 2 Sample 3 Natural rubber 20 30 100 Styrene butadiene copolymer 80 70 0 High surface area white carbon black 100 65 0 Carbon Black N330 10 2 40 Silica dispersant 4 3 0 Aromatic oil 5 13 0 Stable silane coupling agent 8.0 4.8 0 Stearic acid 2 2 0.2 Microcrystalline wax 2 2 0 Antioxidant 4020 2.5 2.5 1.0 Antioxidant RD 2 2 1 Accelerator 1.5 1.0 1.0 Sulfur powder oil filling 1.3 1.3 2.6 Zinc Oxide 3.5 3.0 4.2

[0041] Fresh cross sections were cut from the vulcanized cylindrical specimens of Sample 1, Sample 2, and Sample 3, and the circular cross section had a diameter of 2 cm and a thickness of 1 cm.

[0042] Connect the colorimeter power supply, open the colorimeter test software system, and complete the calibration of the colorimeter equipment.

[0043] Take out the standard black plate and conduct three Lab mode colorimetric tests, take the three average values ​​as the benchmark data, and record them as L0, a0, and b0 respectively, then conduct three Lab colorimetric value tests on the cross sections of sample 1, sample 2, and sample 3, and record them as L1, a1, b1, L2, a2, b2, and L3, a3, and b3 respectively. The test data are shown in Table 2;

[0044]

[0045] Color difference between sample 1 and sample 2

[0046] Color difference between sample 1 and sample 3

[0047] From the color difference data analysis, it can be seen that the color difference between sample 1 and sample 2 is significantly lower than the color difference between sample 1 and sample 3;

[0048] In order to determine the accuracy of the colorimeter test, composite samples of sample 1 and sample 2, sample 1 and sample 3 were prepared at the same time. The sample size was a cylinder with a diameter of 2 cm and a height of 3 cm. After cutting a fresh cross section, it was photographed and observed under the same light intensity and light direction under a stereo microscope. The photos are shown in the figure. Figure 1 shown.

[0049] From the stereo microscope photos, we can see that the color difference between sample 1 and sample 2 is significantly lower than that between sample 1 and sample 3, which is consistent with the test results of the colorimeter. The use of a precision colorimeter can accurately express the data and avoid the influence of subjective factors in human evaluation.

[0050] Example 2

[0051] Samples were taken from semi-steel radial tires containing upper and lower tread rubbers to verify the colorimeter color difference evaluation method.

[0052] Samples were taken from two semi-steel radial tires with upper and lower tread rubbers for testing. The sample section diameter was 1.2 cm and the thickness was 0.5 mm. The upper and lower treads of the first tire were sample 1 and sample 2 respectively, and the upper and lower treads of the second tire were sample 3 and sample 4 respectively.

[0053] Connect the colorimeter power supply, open the colorimeter test software system, and complete the calibration of the colorimeter equipment.

[0054] Take out the standard black plate and conduct three Lab mode colorimetric tests, take the three average values ​​as the benchmark data, and record them as L0, a0, and b0 respectively, then conduct three Lab colorimetric value tests on the cross sections of sample 1, sample 2, sample 3, and sample 4, and record them as L1, a1, b1, L2, a2, b2, L3, a3, b3, L4, a4, and b4 respectively. The test data are shown in Table 3;

[0055]

[0056] Color difference between sample 1 and sample 2 Color difference between sample 3 and sample 4

[0057] From the color difference data analysis, it can be seen that the color difference between sample 1 and sample 2 is significantly lower than the color difference between sample 3 and sample 4. Corresponding to the actual tire wear effect, the color difference between the upper and lower treads of the first tire is smaller, and the color difference between the upper and lower treads of the second tire is larger. Figure 2 As shown, this is consistent with the color difference test results of the precision colorimeter.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for evaluating color difference of a rubber composite material, characterized in that: The following steps are involved: Step 1: Sample preparation: Select two or more different rubber composite materials and prepare samples with smooth cross-sections; Step 2: Chroma test: Use a precision colorimeter and standard plate test data as a benchmark to perform chroma tests on cross sections of different rubber composite samples and record the sample measurement data values; Step 3: Analyze data: Analyze the chromaticity data of the test samples to obtain the color difference value △E between each sample.

2. The method for evaluating color difference of rubber composite materials according to claim 1, characterized in that: The colorimeter is a precision colorimeter capable of performing one or more of Lab, RGB, and XYZ colorimetric mode measurements.

3. The method for evaluating color difference of rubber composite materials according to claim 1, characterized in that: The test sample is one or both of a vulcanized rubber composite material and an unvulcanized rubber composite material.

4. The method for evaluating color difference of rubber composite materials according to claim 3, characterized in that: The vulcanization method of the vulcanized rubber composite material can be one or more of sulfur vulcanization, metal oxide vulcanization, resin vulcanization, peroxide vulcanization, and thiuram vulcanization.

5. The method for evaluating color difference of rubber composite materials according to claim 1, characterized in that: The specific analysis in step three is: Then, the cross sections of sample 1 and sample 2 were tested for Lab chromaticity values ​​three times and recorded as L1, a1, b1, L2, a2, b2 respectively.

6. The method for evaluating color difference of a rubber composite material according to claim 1, characterized in that: The test sample cylindrical specimen is cut into a fresh cross section, and the circular cross section diameter and thickness are kept uniform.

7. The method for evaluating color difference of rubber composite materials according to claim 5, characterized in that: The cross sections of the samples 1 and 2 were subjected to three Lab chromaticity value tests, and the three average values ​​were taken as the benchmark data.

8. The method for evaluating color difference of a rubber composite material according to claim 1, characterized in that: After cutting the fresh cross section in step 2, take photos and observe under the same light source intensity and direction under a stereo microscope.

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