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Analysis On The Difference Of Fiber Content Test Standards Between China And America

2012/2/2 10:30:00 55

The United States is the most important clothing textiles in China exit China is also the largest textile consumer market in the world. Products exported to the United States must comply with the local laws and regulations of the United States, especially for the labeling of fiber ingredients. The United States has strict labeling laws and regulations to guide manufacturers and retailers to label fibers correctly. In order to ensure the correctness of the label, the correct test method should be used first. This paper compares and analyzes the differences of fiber content test methods between China and the United States, and provides relevant information for domestic production and trade enterprises, so that they can correctly analyze and label the fiber content of products according to the export regions, so as to meet the market requirements.

　　 Characteristics of American fiber content test standard

The American Association of textile dyers and Chemists (AATCC) is very authoritative in the field of textile testing standards. The AATCC test method for textiles developed by AATCC covers the analysis of textile fiber composition, Color fastness Test standards for physical properties of fabrics and experiments. AATCC standard is the most widely used test standard for textile products entering the U.S. market.

AATCC standard has two methods in fiber content test, aatcc20 standard is fiber qualitative analysis method, aatcc20a standard is fiber quantitative analysis method. Qualitative analysis of fibers includes microscopic observation of longitudinal and transverse sections of fibers, combustion method, density method, dissolution method, dry twisting method, viscosity method, melting point method and infrared spectroscopy method. Aatcc20a is a quantitative analysis of fibers, including microscopic analysis, chemical dissolution and resolution.

　 Differences between Chinese standards and American standards

The fiber content test of textile products in China is based on FZ / T 01057-2007 "textile fiber identification test method" and GB / T 2910 "textile quantitative chemical analysis". There are also industry Methods and standards for special products formulated by the association and relevant institutions, such as FZ / T 01095-2002 "Textiles - Test Method for fiber content of Spandex Products", GB / T 16988-1997 "determination of the content of special animal fiber and sheep wool mixture", FZ / T 30003-2009 "quantitative analysis method of hemp cotton blended products" and FZ / T 01026-2009 "quantitative chemical analysis of four component fiber mixtures" Etc.

　 2.1 qualitative analysis method of fiber

In all detection institutions, the most widely used methods for fiber identification should be microscopic observation and dissolution. For special fibers, combustion method and infrared spectroscopy are also used. Other methods are seldom used due to accuracy and operability in the actual detection process. Now, several qualitative analysis methods are introduced.

　 2.1.1 microscopic observation

Microscopic observation relies on biological microscope as a tool, through the technical personnel directly observe the longitudinal and transverse cross-section of the fiber, so as to preliminarily determine the type of fiber. An experienced technician can judge natural fibers such as cotton, hemp, silk and wool, as well as some chemical fibers such as viscose and spandex. AATCC 20 "fiber qualitative analysis" standard and FZ / T 01057-2007 "textile fiber identification test method", in addition to the language description of the longitudinal and transverse appearance of each kind of fiber, it also provides a large number of fiber pictures to give a more intuitive cognition.

　　 2.1.2 dissolution method

China's industry standard FZ / T 01057.4-2007 "dissolution method for textile fiber identification" requires that the samples should be vibrated at room temperature (20 ℃ ~ 30 ℃) for 5min or boiled for 3min to observe the dissolution of samples. The dissolution test in aatcc20 provides three kinds of dissolution time, which are 5min, 10min and 20min. In addition to the normal temperature of 20 ℃, there are 50 ℃, 90 ℃ and boiling.

For example, dimethylformamide dissolution confirmation test It is required to treat at 90 ℃ for 10 minutes and then observe the dissolution phenomenon. Due to the different dissolution conditions, the dissolution of some special fibers will be different. Therefore, the inspector should observe carefully and distinguish them.

　　 2.1.3 dry twisting method

In aatcc20, the dry twist method is used to preliminarily judge bast fiber. Take parallel fiber bundles, immerse them in water, hold one end and make the other free end face the observer. Heat them with hot air on an electric stove. During the drying process, the flax and ramie fibers rotate clockwise, while the hemp and jute fibers rotate anticlockwise.

　 2.2 fiber quantitative analysis method

Except for some methods, GB / t2910-2009 adopts the latest version of iso1833, which is quite different from American standard system. American aatcc20a standard includes water content, non fiber material removal, fiber content resolution, fiber content chemical analysis and fiber content microscopic analysis. According to different methods, there are special standards for fiber quantitative analysis in China. In domestic fiber content analysis, special attention should be paid to the selection of methods. GB / t2910 is a quantitative chemical analysis method for fibers (manual resolution method is provided in the appendix), and GB / t16988 is a microscopic analysis method for animal fibers, etc.

　　 2.2.1 quantitative fiber analysis

Aatcc20a provides eight chemical analysis methods: 100% acetone method, 20% hydrochloric acid method, 59.5% sulfuric acid method, 70% sulfuric acid method, alkaline sodium hypochlorite method, 90% formic acid method, dimethylformamide and dimethylacetamide method. GB / t2910 provides 23 kinds of chemical analysis methods, covering all testing methods of aatcc20a. Now from the sample preparation, reagent choice The differences between the two methods are analyzed.

　　 1) Sample preparation (see Table 1)

Table 1 Comparison of sample preparation methods

Although the expression of sampling weight is different, according to practical experience, the sampling requirements of the two standards can meet the representativeness and accuracy of the test. In the process of sample weighing, AATCC clearly requires the sample to be dried to constant weight, and has clear requirements for constant weight. However, GB / t2910 can also meet the requirements of actual constant weight with long drying time, but aatcc20a is more operable.

　　 2) Reagent selection

In the same fiber content analysis process, there are similarities and differences in the selection of reagents in the dissolution process between AATCC and Chinese standards (see Table 2).

Table 2 Comparison of dissolving reagents of some methods

　　 3) Test procedure

There are three different procedures for viscose fiber analysis.

Table 3 Comparison of operation procedures for chemical analysis of viscose fiber and cotton blended products

Because viscose and cotton are cellulose fibers, both of them will damage cotton fiber during chemical dissolution. Any small difference in temperature, time and oscillation in operation procedure will affect the final result.

　 4) data processing

Results aatcc20a was only used for viscose fibre The loss compensation factor is introduced when blended with cotton, and no correction or compensation factor is used in all other chemical analysis methods. In GB / T 2910, the mass loss correction coefficient is provided for each type of test, and the reported results are calculated by combining the test data with the corresponding correction coefficient to ensure the accuracy of the test results.

The percentage of fiber weight in China should be determined according to the moisture regain standard. Although there is no clear requirement in the American Standard, the report issued by the testing agency is still combined with the public determined moisture regain. Due to the difference in the standard system of the two countries, the results may be different, so the correct value of the moisture regain must be selected in the calculation. The comparison of moisture regain of two typical fibers is shown in Table 4.

Table 4 Comparison of moisture regain of wool and regenerated cellulose fibers

　　 2.2.2 microscopic quantitative analysis method

For example, the density of wool and cashmere in aatcc20a is 1.31, while the density of wool and cashmere in China is 1.31 and 1.30 respectively. In the calculation formula, GB / t16988 combines the standard deviation of diameter to calculate the area, while aatcc20a only describes the area by calculating the diameter.

　　 2.3 multicomponent analysis

The part of GB / t2910.2 in China is multi-component content analysis, in which four kinds of dissolution schemes are introduced in detail, and the calculation is carried out in combination with the mass loss correction coefficient. However, AATCC 20A does not have such detailed calculation and analysis. In the process of multi-component content analysis, it is necessary to carefully select the dissolving reagent and dissolution sequence according to the working experience to ensure the selected one reagent The residual fiber will not be damaged, resulting in the reduction of data accuracy.

　　 3 conclusion

To sum up, there are many differences in fiber composition analysis methods between China and the United States, and the testing institutions select test methods according to the export place of products. Enterprises should pay attention to the difference between the test data and the national standard data when the products are exported to the United States, and formulate the fiber labels that meet the market requirements according to the test data.

In order to ensure the accuracy of the test method for different testing institutions, it is necessary to strictly master the relevant test methods for the enterprise.