Martindale test method for abrasion resistance of PU coated fabrics for car seats

The MIE test method for the abrasion resistance of coated fabrics for car seats has the disadvantages of a time-consuming and single friction route, and it is proposed to use the MARTINDALE test method to replace it. The two test methods are compared, and the results show that the latter can not only improve the efficiency of the test, but also improve the accuracy of the test results to varying degrees. Using the MARTINDALE test method, when the number of tests reaches 400 times, the surface gloss of the sample changes significantly, which can be used to quickly evaluate the wear resistance of PU synthetic leather; after the number of tests reaches 1600 times, the change of the surface gloss of the sample is basically stable. The test times can be set as the standard test times of the wear resistance index. In addition, the choice of the friction medium will affect the test results of the wear resistance of PU-kunstleer influence.

1. Foreword
Coated fabric (hereinafter referred to as synthetic leather) is one of the three flexible materials commonly used in the design of modern car seats and resembles natural leather. Due to the limited natural leather resources, high price and high environmental protection requirements in the processing process, major car manufacturers have developed synthetic leather for car interiors. Among them, PU coated fabrics are currently the most common synthetic leather materials for car interiors.
Abrasion resistance is one of the most important indicators for evaluating the performance of PU synthetic leather for car seats. The current method of testing the abrasion resistance of PU synthetic leather for seats is the MIE abrasion resistance test method, which is mostly used by French automobile companies. , the friction method is \"reciprocating two-way friction\", and the test time can be divided into 8, 12 and 16 hours. Because this testmethod has flaws such as time-consuming and single friction route, the friction effect is not ideal. Therefore, a more effective alternative method of wear resistance testing should be found to achieve better test results. Since both MIE abrasion resistance test and MARTINDALE abrasion resistance test (hereinafter referred to as MAR) were originally used to test lint/pilling of fabrics, both use standard woolen fabrics as the friction medium and MAR abrasion resistance test method is used in fabrics Very good test results in the fuzzing/pilling test. For example, the MAR tester can test multiple samples at the same time, which is beneficial for improving testing efficiency; in addition, there is a low-pressure continuous reversing friction between the sample and the friction medium, and the relative friction track is the Lissajous track, so that all parts of the sample are rubbed. The probability is the same and the direction of friction is uniform. OBased on the advantages of the MAR test method for abrasion resistance, this paper examines the feasibility of using the MAR test method instead of the MIE test method to test the abrasion resistance of synthetic leather for car seats.

II. Experiments and Results
The parameter for evaluating the abrasion resistance of synthetic leather for car seats is the change of the surface gloss of synthetic leather caused by surface abrasion. The surface of brand new artificial leather has certain lines and is not smooth. After a period of friction, the lines will gradually disappear and the surface of the material will become smoother. A gloss meter (gloss meter 60°) was used to measure the surface gloss of PU synthetic leather, and the wear rate of the PU leather surface was shown by comparing the change in gloss of the synthetic leather surface before/after wear.
To accurately evaluate MIETest method and MAR-test method on the test effect of the wear resistance of synthetic leather for car seats. The samples used in the test are taken from 7 kinds of synthetic leather for seats commonly used by a well-known European car manufacturer, and their styles, textures and performance are different . , to ensure that the test results are representative. Each sample was tested for abrasion resistance using two different test methods, MIE and MAR.
The MIE abrasion resistance test is carried out according to the standard Renault PSA D44 1073 (Abrasion test of materials for car interior decoration), and the test time is
8 hours; MAR abrasion resistance test is performed according to standard Renault PSA D44 1846 (textile pilling, pilling test), the test instrument model is MARTINDALE 103 (4 head type). According to the precedent of the wear resistance test of PU synthetic leather, the weight of the hammer is selected at 1400g, the number of rubs is 3200 times (about 60 mins) and the abrasion resistance of the surface of PU synthetic leather is recorded at 1600 times (about 30 mins) gloss value. The test conditions meet the test standard, that is, the temperature is 23 ± 2 ° C and the humidity is 50% ± 5%. Table 1 summarizes the specifications of the standard friction media used in the two test methods.
Observing the whole wear-resistant testing process, there were no abnormal phenomena such as cracking, deformation and sharp rise in the surface temperature of the synthetic leather during the test. The test results of the wear test are shown in Figure 1. In the figure, MAR1600 indicates that the number of rubs is 1600 times, and MAR3200 indicates that the number of rubs is 3200 times. In addition, at the request of the manufacturer, the sample information is not published and Arabic numerals are used to indicate the 7 sample numbers in the figure.
After the schhour test, the gloss changes of all samples were greater than zero, indicating that the surface gloss of the samples improved to varying degrees after rubbing. In addition, the test effect of the MAR method is significantly better than that of the MIE method, that is, assuming the improvement of the test efficiency, the difference in gloss of the samples before and after the test is obvious (No. 1, No. 3, No. 4, No. 7) Or equivalent to the MIE method (No. 2, No. 5, No. 6). This shows that using the MAR test method to test the wear resistance of PU synthetic leather can not only improve the efficiency, but also ensure that the test results are accurate.
Upon further observation, it can be seen that the surface gloss of PU synthetic leather increased significantly within the first 1600 times, and the surface gloss did not change much as the test continued, indicating that the surface abrasion effect of the sample tended be stable. Picture 2 showsthe results of 0-1 600 MAR abrasion resistance tests on a typical sample (No. 4). The results show that the standard rubbing times of PU synthetic leather can be set to 1600 times. In this way, it saves time and ensures the reliability of test results.
Looking further at Figure 2, the sample\'s gloss quickly increases to about 400 times, after which the upward trend slows down. Therefore, you can try to use 400 times as an effective observation point to quickly observe the wear of the material. To demonstrate the feasibility of this conclusion, the MAR friction test was performed on 7 samples from 0 to 400 times, and every 50 The gloss value of the surface of the material is recorded for the second time (to measure the change of the surface gloss of the material in more detail in the initial period of the test, the value is taken every 25 times during the period from 0 to 100 times).
DThe surface gloss of the sample rapidly increases to 300 times, and for the first time reaches a relatively stable state between 300 and 400 times (except No. 5 and No. 7), showing that 400 times is used as a quick observation The idea of a point of view of material wear is feasible. Basically, between 0 and 400 rubs, the surface gloss of the sample increases rapidly and the surface wears quickly, and after 400 rubs, the surface gloss of the sample slowly increases and the wear rate slows down.
During the wear test of No. 5 and No. 7, it was found that the surface of the friction medium became abnormally rough and severe pilling/pilling occurred, making the test results unrepresentative. To solve this problem, the friction medium was replaced with the standard friction medium used in the MIE test (see Table 1 for specifications), and the MAR test (0~400 times) was repeated for No. 5 and no. .7. In figure 4, te see that the surface of the replaced friction medium no longer exhibits lint/pilling and that the test process is stable. The wear resistance test of No. 5 and No. 7 before/after replacing the friction medium, the results are shown in Figure 5 (the test data recording method is the same as in Figure 3).

3. Conclusion
The above test results show that it is feasible to use the MAR method to test the wear resistance of PU synthetic leather, and the test effect is better than the current MIE test method. As a method to quickly evaluate the wear resistance of PU synthetic leather, the number of rubbing of the MAR method can be set to 400 times; if more accurate data is required, the number of rubs can be set to 1600 times. In addition, the friction medium will affect the test results of the abrasion resistance of PU synthetic leather, and more research is needed on the selection of the friction medium for the MAR test method.

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