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Establishment Of Global Cashmere Quality Standard

2011/3/16 15:49:00 132

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The establishment of the global cashmere quality standard is the theme of the fifth international cashmere forum. At present, the definition of cashmere, the standard of fiber identification and some testing methods are not uniform in the world. When products are sold to different countries, they often need to know first. Exit The quality requirements of the country of destination, the quality requirements from different countries, make foreign trade enterprises feel cumbersome and difficult to remember. China is not only a large producer of cashmere raw materials, but also a large producer and exporter of cashmere products. Therefore, the establishment of a unified global cashmere. quality standard No doubt, it will bring convenience to Chinese cashmere foreign trade enterprises, especially the foreign trade enterprises that export target markets all over the world.

Cashmere products are high-grade textile products, so most of their quality requirements are interlinked with textiles, such as color fastness, dimensional stability of washing or dry cleaning, safety and environmental protection. But because of cashmere raw materials and other textile animals. fibre The great difference in price and the limitation of animal fiber identification methods bring many sensitive problems to cashmere products, which are different from other textile quality. For example, whether the goat's hair is cashmere, whether the cashmere product is allowed to contain non cashmere fiber, how much difference is the fiber content of cashmere blended product, and which test method should be used to determine the diameter of the cashmere product.

This article gives a brief introduction to the existing international differences in these aspects, and puts forward the problems that should be considered in establishing the global cashmere quality standard.

1 definition of cashmere

There are some differences in the definition of cashmere in different countries and regions. The average diameter is 18.5 u m or thinner; the fibers with similar diameters obtained from the wild goats in Australia, New Zealand and Scotland can also be considered as cashmere; the American wool product labelling method (The U.S. Wool Products Wool 1939) added the definition of cashmere (15 15) (6), which was implemented in January 1, 2007. They defined cashmere as follows: (1) the fine (carding) fuzz from the cashmere goats; second, the average fiber diameter was not more than 19 UG; and (3) cashmere fibers containing more than 3% (weight ratio) diameter greater than 30 mu, the diameter coefficient of variation of the fiber should not exceed 24%. For example, the ninth edition of "textile terms and definitions" (The Textile Institute) International Commission on textile terminology and definition) the definition of cashmere is: the underlying fluff originating from Capra hircus laniger. In addition to the 3 articles mentioned above, the American law and the International Association of cashmere and camel hair manufacturers (CCMI) on cashmere also emphasize that cashmere fibers usually do not contain pulp chambers. In China's GB11951 1989 "textile natural fiber terms", cashmere is defined as the wool fiber obtained from cashmere goat (Capra hircus laniger). Table 1 compares the definition of three kinds of cashmere.

Table 1 Comparison of three cashmere definitions

If we want to establish the global cashmere quality standard, the definition of cashmere should be clearly stipulated that cashmere goats are produced from cashmere goats. The maximum average fiber diameter and diameter variation coefficient should be stipulated on the basis of taking full account of the inherent quality parameters of all cashmere goat fiber resources in the international velvet country. The percentage of fiber weight greater than 30 m should also be stipulated, because many cashmere garments will be directly exposed to the skin when they are dressed, and the roughness is related to the wearing comfort. Research shows that when the fibers containing more than 30 m diameter in the textile yarns exceed a certain number, they will feel itchy.

2 identification standard for cashmere fiber

At present, different countries have different requirements for the identification of fiber content of cashmere products, as shown in Table 2.

Table 2 specifications for fiber identification of cashmere textiles in various countries

Product fiber content in China, USA, Europe and Japan

Note:

(1) about 100% cashmere: because now in China, the so-called morphological variation cashmere and the real sheep hair are reported as wool in the testing report, which makes people mistakenly believe that 100% cashmere products in China allow 5% wool, and at the same time, it also creates a multiplying opportunity for those who are interested in adulteration.

(2) the provisions for labeling the cashmere products in the United States, Europe and Japan in the above table are derived from the relevant national laws and regulations, but many buyers are required to be stricter in export.

If we establish the global cashmere quality standard, we should make a uniform stipulation on the identification of fiber components of cashmere textiles. In general, the difference between the marked value of a product's fiber content and the test result shown in the test report does not exceed the tolerance difference stipulated in the fiber content. We will think that the fiber content of the product meets the requirements. Judging from the allowable difference of fiber content stipulated by different countries, this label is obviously not the true value of fiber content, but the design value (i.e. technical content), because the uncertainty of measurement (the 95% confidence interval of fiber dimension) will not be as large as 3% for most chemical fiber dissolution test methods. Due to the existence of measurement uncertainty, any test result can not be regarded as the true value of fiber content. Especially for cashmere and other animal fiber blended products, the confidence interval of test results will vary greatly according to blending ratio and sample size (see IWTO 58-00). The uncertainty of truth must be considered. In view of this, the allowable difference between the confidence interval of test results and the true value and the design value should be taken into full consideration in the cashmere blended fabric's allowance for fiber content.

To be sure, the tolerance of 3% is too strict for cashmere and wool blended than 50/50, because the confidence intervals of detection are greater than 3%.

3 testing method for cashmere

3.1 fiber content

At present, the standardized detection method is only a microscope method. Other objective testing methods, such as DNA analysis, are limited or not fully standardized.

The microscopic method is divided into electron scanning electron microscopy (SEM) and optical microscopy (LM). The essence of these two methods is subjective determination of fiber genera. The microscope is only a means of amplifying the fiber, which enables the inspector to clearly distinguish the scale characteristics of the fiber surface, but the accuracy of the test results depends entirely on the experience of the inspector. Internationally, there are some differences between the different standards of the method, as shown in Table 3.

Table 3 Comparison of test methods for fiber content of cashmere and other animal fiber mixtures

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3.2 fiber diameter

Commonly used animal fiber diameter test methods and corresponding standards are as follows: 1) optical fiber projection method / optical fiber mirror combined with CCD method: ISO 137, IWTO 8, ASTM D2130, GB/T 10685; 2) OFDA (OFDA100/2000/4000):IWTO 47; 3) Sirolan- laser scanning method: IWTO 12; 4) airflow meter method: 6 6. Among them, because the airflow meter can only measure the average fiber diameter, it can not give the information of diameter standard deviation, that is, the uniformity of diameter, and is seldom used in cashmere. The other three methods can be used in cashmere, but the equipment used in laser scanning is difficult to maintain, so it is relatively less applied.

There is no authoritative conclusion on the difference of test results of the same sample by different methods. However, considering the principle of the test, if the results of the different methods are controversial, the optical fiber projection method should be the criterion, but we should pay attention to the requirement that the sample size should be large enough to meet the allowable error rate under a certain confidence limit.

3.3 fiber length

There are 1 methods for testing the length of animal fibers: (2) hand hand arrangement: GB 18267, FZ/T 21003; 2) Classifiber: test principle and ASTM D 1447; 3) comb method: ASTM D1575, ISO 920, IWTO Draft TM-1, 6501 6501; 4) almitt method: 2648, 4, 21293 21293; 21293) single fiber test method:

The characteristics of fiber length testing equipment and the range of the inherent length parameters of goats determine that the selection of the above methods is limited to the test of cashmere length, as shown in Table 4.

Table 4 applicability of fiber length test method

3.4 pilling

At present, the international commonly used cashmere knitwear pilling test methods and standards are: 1) ICI pilling box method: ISO 12945-1, JIS L 1076 A, GB/T 4802.3; 2) Martin Dyer method (Martindale):ISO 12945-2; 3) random roll method (Random Tumbling):ASTM 3512.

The establishment of cashmere quality standards should be consistent with cashmere testing methods, because there is no comparability between test results obtained by different test methods. Considering the characteristics of cashmere fiber and products, the recommended test methods are as follows:

1) fiber content test: ISO 17751

2) fiber diameter test: optical microscope projection as the principle of test method or OFDA method.

3) fiber length test:

A) carding: Classifiber

B) velvet strips: almitt method

C) yarn: it is recommended not to be tested. The single fiber test method is used only for comparing the length of the fibers in the two yarns.

D) pilling pilling: Knitwear: ICI pilling box; woven fabric: Martin Dyer method (Martindale)