Introduction To Testing Methods And Related Technologies Of Color Fastness

　　1、 Color fastness Practicality and importance of testing

People are spin The general concern about color fastness is not only because the textiles with poor color fastness are easy to fade and stain other fabrics, but also because recent research shows that because of the poor color fastness of fabrics, the human body dissolves the dye through friction, sweating and other forms, and is absorbed by the human body through the skin. When dye molecules enter the human body, they will be decomposed and reduced into harmful components under the action of human enzymes, forming chemical substances such as carcinogenic aromatic amines to harm people.

With the upscale clothing With more and more exports, foreign businessmen have increasingly high requirements on the appearance and internal quality of clothing. Color fastness is almost a must for all types of clothing. Recently, in addition to the conventional color fastness to washing, rubbing and perspiration, there are more and more export contracts that stipulate the color fastness to light of clothing. However, the requirements of ordinary consumers for clothing have changed from wearability to comfort and beauty, while the requirements for color are always new. Therefore, in recent years, the requirements for color fastness to sunlight climate are increasingly high.

In order to adapt to China's accession to the World Trade Organization (WTO), The National Bureau of Quality and Technical Supervision issued the formulation in 2000 (General safety technical requirements for textiles). This standard will be implemented from January 1, 2002. Products produced before December 31, 2001 and meeting the corresponding product standards are allowed to be sold on the market until December 31, 2003. After the implementation of this standard, if the safety technical requirements for textile products in other relevant product standards are inconsistent with this standard Shall prevail. The implementation of General Safety Technical Requirements for Textiles is indeed a test for textile printing and dyeing enterprises. Enterprises must carefully analyze various factors affecting color fastness, improve production processes, and ensure that products meet the requirements of mandatory standards. Only in this way can they occupy a place in the international market.

2. Existing color fastness test standards and means

The so-called color fastness (color fastness for short) refers to the degree of fading of dyed fabrics under the action of external factors (extrusion, friction, water washing, rain, exposure, etc.) during use or processing, and is an important indicator of fabrics. Dyes are affected by external factors in different ways on clothing materials, so there are various corresponding color fastness, such as sunlight, soaping, climate, chlorine bleaching, friction, perspiration, ironing, etc. They all have corresponding color fastness. The fastness requirements of clothing materials are different due to their different uses or processing processes.

The color fastness depends to a large extent on the chemical structure of the dye, in addition, it also depends on whether the dye fibre And the combination of dyes and fibers. In order to inspect and evaluate the quality of materials, the state has formulated a set of test methods for color fastness, which are implemented as standards in actual production, referring to the wearing situation of clothing. Of course, the actual use of clothing materials is more complex, and these methods are only an approximate simulation.

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The following table shows the commonly used color fastness test contents and corresponding standards in the laboratory:

Because the conditions and requirements of fabrics in the process of processing and use are very different, most of the current test methods are simulation tests or comprehensive tests according to the working environment and conditions, so the content of test methods for color fastness is quite extensive. However, throughout the International Standards Organization (ISO), American Association of Colorists and Chemists (AATCC), Japan (JIS), the United Kingdom (BS) and many other standards, the most commonly used items are washing resistance, light resistance, friction resistance and sweat resistance, ironing resistance, weather resistance and so on.

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3. China's existing color fastness test standards and Europe and America Comparison of

The standardization of textile products in China is formed with the development of China's textile industry. The standards are formulated according to the quality level of the raw materials used and the process conditions applied. From a certain point of view, it is a production standard to guide manufacturers to produce.

Internationally, especially in developed countries and regions such as Europe, America, Japan and other countries, the standards are determined according to the end use of the product, and the corresponding assessment indicators are established, without considering the raw material composition and process differences of the product, so that the assessment indicators are closer to the actual application. Developed countries and regions have put forward the requirements of mandatory testing for color fastness indicators. For example, the most representative "Oko TexStandard100" in Europe lists color fastness as a safety item, carries out mandatory testing, and clearly stipulates specific technical requirements. The American ASTM standard also puts forward high requirements for color fastness. The International Organization for Standardization Technical Committee on Textiles ISOfFC36 has said that "the manufacturing method of textile products is not considered when formulating performance specifications" It is written in its development strategy that after China's accession to the WTO, its standards must be in line with international standards. The General Technical Requirements for Safety of Textiles also establishes corresponding assessment indicators based on the end use of products. According to the end use, the standard divides textiles into three categories: Class A is for infants and young children, Class B is for products in direct contact with skin, and Class C is for products not in direct contact with skin, The specific assessment indicators of color fastness of various products are also specified. The inclusion of color fastness as an assessment index in the General Technical Requirements for Textile Safety not only meets the needs of China's entry into WTO, but also meets the needs of the increasing living standards of our people.

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