Color fastness testing and standards
The American Society of Textile Dyes and Chemical Engineers (AATCC) developed the sun fastness detection standard, is one of the most commonly used authoritative standards, of which the detection method E has attracted much attention in the textile industry. However, due to the limitations of technical conditions, AATCC TM16-1998 is a standard based on hardware characteristics, which does not meet the principles of international standards based on technical performance formulated by industry associations such as AATCC/ISO /ASTM (American Society for Materials and Testing), and limits the promotion of this test project.
AATCC promulgated the new standard AATCC TM16-2003 for the test method of textile sun fastness in September 2003, and compiled it into the 2004 edition of AATCC Technical manual for full implementation. This revision marks the standard from a hardware-based old standard system, officially into a performance-based new standard system, but also for the new technology, new methods in the application of the sun fastness test opened the door, making the cost of equipment and use of the cost has been greatly reduced, the sun fastness test more scientific application more widely.
1, the test principle of color fastness
Generally, the test process for sun fastness is: the textile sample and the mutually agreed reference standard sample (blue standard wool), at the same time under the artificial light source in accordance with the specified conditions, and then compare the degree of discoloration of the two, and through the blue wool fastness standard sample exposed at the same time to determine the light fastness of the sample. All the test standards are relatively comparative, and the exposure equipment does not directly issue test results. The performance of the equipment is mainly
Depends on the control of parameters that affect the test environment, including spectrum, light intensity, temperature, relative humidity, etc. Based on hardware device performance, there are air cooled lamps/water cooled lamps, light filter composition and sample holder rotation speed. However, due to hardware requirements, there is a lack of technology to measure and control key parameters, and the test conditions cannot be adequately and accurately described. The limitations brought by the hardware characteristics are: hinder the technological progress, limit the market competition, and cause the market monopoly. The purpose of describing device hardware performance in the standard is: Similar hardware = similar limitations, similar limitations = similar results. The test environment based on technical performance includes: spectrum definition, irradiation energy, blackboard temperature test chamber air temperature, relative humidity, parameter calibration and consistency with the test environment. Standards based on technical performance promote technological progress, remove barriers to improved control technology, and encourage normal market competition. The new performance-based standard specifies the operating parameters required to achieve certain test results without defining or specifying hardware-based devices. Allows users to select from different test equipment that meets the new performance-based standards. The promulgation of new performance-based standards has promoted the development of science and technology, enabling standards to adopt the latest technical methods in the market in a timely manner.
2. Process of standard revision
New performance-based standards for light and weather resistance testing, derived from ISO-TC-61 (plastics), ISO-4892 (plastics), ISO-11341 (paints and coatings), ISO-18909 (printing inks) and ISO-11341 (sealing adhesives) light and weather resistance documents, All were subsequently revised to performance-based standards. Since then, various societies such as ASTM, SAE and AATCC have improved their standards for color fastness to weather and light.
2.1 Revision of ASTM Weather resistance test standard
The ASTM G03 Committee first developed new performance-based light and weather resistance guidelines. It is responsible for the overall management of common weather test technical specifications for accelerated exposure to outdoor and laboratory tests. Test methods for materials in different industries (paints, plastics, textiles, etc.) refer to the G03 test specification. Table 1 compares the old and new ASTM weathering test standards.
The AST M G151 is a general principle for exposure of non-metallic materials in accelerated test equipment using laboratory light sources. It describes general test procedures for various laboratory light sources and can be applied to all light stability and weather resistance tests. The general principles discuss the sources of test differences (such as outdoor exposure versus laboratory acceleration), specify the use of reference materials, uniformly define acceptable irradiance and methods of measurement in the test chamber, and provide effective methods for measuring chalkboard temperature, air temperature in the chamber, and relative humidity. ASTM G155 is the standard for xenon arc equipment used for exposure of non-metallic materials. It defines the spectral power distribution of daylight as a laboratory light source and daylight through window glass, and specifies the irradiance index and tolerance. For the test chamber environment, as long as the appropriate spectrum is provided, the three key test parameters of light, temperature and humidity are controlled, and other different designs are allowed.
2.2 Revision of the AATCC TM 16 color fastness standard to light
In May 2003, AATCC approved a new performance-based color fastness test standard to light. Among them, TM 169 "Color Fastness to Light" is suitable for indoor textiles; TM 169 "Weather Resistance of Fabrics: Xenon Arc" for outdoor textiles; TM 192 Weather Resistance: Solar Carbon Arc.
Textile suppliers, manufacturers and test equipment manufacturers who are members of the AATCC RA50 and RA64 committees contributed to the revision of the standard. AATCC TM 16 is a widely used textile light stability test standard for carbon and xenon arcs. TM 16 Old versions use "A", "D", "E", "F", "H", "I", and "J" to indicate different options for testing, while new versions of TM 16 use numbers "1 to 5" to indicate different options. The most widely used xenon arc test cycle selected "16E" was replaced by "16-3", and the selection "E" in older versions is no longer used.
Table 2 compares AATCC TM16 with AATCC TM16E-1998 and ISO 105 B02-1994.
As can be seen from Table 2, in the new standard system AATCC TM16-2003, the technical performance requirements replace the hardware performance-based provisions in the old standard. The new xenon lamp test standard reflects the spectral requirements of quantified light sources for technical performance, listing the spectral distribution and tolerance of artificial sunlight and sunlight through glass Windows, and the spectral bandwidth accuracy of 20 nm. When testing according to the new standard, it is recommended to use a light irradiance sensor, and the sample holder can be either rotated tympanic or flat. In the new standard, the irradiation source uses one or more lamps, and the cooling method is divided into water cooling and air cooling. The new standard also lists the technical conditions that xenon arc test equipment should have and the control of system irradiation intensity, blackboard temperature, test chamber air temperature and relative humidity, as well as the calibration of all the above parameters.
The revision of the new standard focuses on "number" and "quantity", and downplays the hardware structure of specific equipment. ASTM G151 states that the original standard describes equipment design details in excessive detail.
3. Technical research and test proof of new standards
As an important part of the revision of the standard, the relevant authoritative standard organizations and associations have conducted a large number of tests and studies on the feasibility of the revision of the standard and whether the equipment conditions for the technical performance of the new standard are available, providing a detailed technical basis for the revision of the standard.
3.1 Xenon arc test equipment with different structural designs
(1) Rotary drum equipment (ATLAS)
Originating in 1918, the device has a light source in the center, a filter system around it, and the sample rotates with the tympanic chamber, which rotates around the light source, as shown in Figure 1.
(2) Static plane equipment (Q-Lab Company)
The lamp tube is placed on the top, and the filter is located below the lamp tube, with a mirror reflection system; The sample is located under the lamp and can be tilted to prevent water from running away quickly.
3.2 Study by ASTM (American Society for Testing Materials) G03 Working Group
The AST M G03 working group, which specializes in weather resistance and durability testing, tested and compared several materials in five laboratories around the world using different models of Q-Sun flat type and ATLAS rotary light resistance and weather resistance testers. The test results show that as long as the corresponding spectral filtration system and exposure conditions are used, under the same test environment, using the test standards based on technical energy, the two kinds of structural design of different color fastness testing machines get the same results.
The consistent results obtained from the blue standard wool test demonstrate the feasibility of applying the technical performance of the color fastness standard to the sun (Figure 2,3).
3.3 Rotary tympanum and static flat sample placement system
The ideal tester should produce uniform irradiance, temperature and humidity throughout the test chamber, and the technical performance of a test chamber can be judged by detecting differences in the exposure results of different samples in the same environment (Table 4,5).
Six laboratories with years of xenon arc testing experience participated in the study, including three BASF manufacturers in Southfield, Michigan, Wyandotte, and Munster, Germany, and two independent testing laboratories (A2LA American Laboratory Accreditation Commission, ACT Laboratories in Hillsdale, Michigan, USA and Q-Lab Climate Lab in Miami, Florida, USA) and an equipment manufacturer.
3.4 Test Conclusion
The degradation consistency in a rotating tympanic chamber ranges from ±3% to ±13%, depending on the material type and exposure conditions, to ±3% to ±8% for a flat static system, where the sample is shifted during the test, the degradation consistency in a flat arrangement is better. But more often than not, even without shifting, the consistency of the planar arrangement is as good or better than that of the rotating tympanum. For the best results, it is recommended to test multiple samples (at least 3) of each material and then take an average. Manual displacement of samples in the rotating tympanum and planar arrangement of the test chamber can be arranged as planned.
