In an effort to predict the light fastness of a material over time, many procedures have been employed to accelerate the fading response of a material to exposure to the elements. One test used to accelerate and test the fading process of a material is described in Society of Automotive Engineers publication SAE J1885 (hereby incorporated herein in its entirety by specific reference thereto). In SAE J1885 a sample is subjected to an artificial light source, such as a Xenon-Arc light source, to induce fading in the material for subsequent analysis.

However, some dissatisfaction has remained in the industry about the ability of these procedures to accelerate the fading of the material in a manner that approximated fading of the material as it occurred over time in natural sunlight.

To more closely approximate the actual fade of materials in an accelerated process, alternate procedures have been employed that use radiation from the sun (natural light source) on materials in a controlled chamber located at a specific location. For example, in General Motors Weathering Exposure Tests For Interior Trims GM9538P (hereby incorporated herein in its entirety by specific reference thereto), samples of material are placed in a conditioned chamber and exposed to the sun at a location in the desert. However, although these procedures are accelerated, they require significantly more time than the prior procedures using artificial light. Therefore, there is a need for procedures that can more closely approximate the fading of materials over time, such as with the procedures using natural light, with the shorter time periods experienced with procedures using artificial light.

Brief Description of the Drawings These and other features, aspects, and advantages of the present invention will become better understood with regard to the invention, appended claims, and accompanying drawings where: FIG. 1 shows a block diagram of a controlled irradiance apparatus for use in the present invention; and Fig. 2 shows a block diagram illustrating the process of the present invention.

Detailed Description Referring now to the figures and in particular, to FIG. 1, there is shown a controlled irradiance apparatus 10 for use in the method of the present invention.

In one embodiment, the controlled irradiance apparatus is a Cl 5000 Xenon-Arc Weather-Ometer, manufactured and sold by Atlas Electric Devices Company in Chicago, Illinois. The controlled irradiant apparatus 10 generally includes a light source 20, a filter system 30, and a sample chamber 40.

In one example the light source 20 is a Xenon-Arc 12,000-watt light source.

The filter system 30 includes a coated infrared absorbing (CIRA) filter 31, a soda lime filter 32, and a lantern with floating glass filter 33. In one example, the lantern with floating glass filter 33 is a filter from Atlas Corporation with a part number of 20-3206-00. The filter system 30 is positioned such that light from the light source 20 passes through the CIRA filter 31, the soda lime filter 32, and the lantern with floating glass filter 33, respectively, before reaching the sample chamber 40. The sample chamber 40 is a temperature and humidity controlled chamber with a position for mounting the sample fabric in front of the filter system 30 for receiving light from the radiation source 20. A black panel sensor 41 inside the sample chamber 40 indicates the black panel temperature inside the sample chamber 40. Exposure portions of a sample 60 are mounted within the sample chamber 40 adjacent to the black panel sensor 41.

Referring now to FIG. 2, there is shown a block diagram of a fading and testing procedure 100 for exposure fading and testing of material. The fading and

testing procedure begins with the step 110 of analyzing a reference portion of a sample fabric for color value, chroma, or hue. The sample material can be, but is not limited to, woven fabrics, knitted fabrics, nonwoven textiles or the like. In step 120, the results of the analysis in step 110 are recorded as a base point.

In step 130, a plurality of exposure portions of the sample is positioned in the sample chamber of a controlled irradiant apparatus, such as the apparatus 10 in FIG. 1 described above. In step 140, the environment of the sample chamber is brought to a relative humidity of from about 45% to about 65% and a dry bulb temperature of from about 65°C to about 85°C. In step 150, the light source of the controlled irradiance apparatus causes the exposure portions of the sample to be subjected to a substantial portion of the light in a band width of from about 300nm to about 420nm. During the light conditions from step 150, the environment conditions from 140 are maintained in the sample chamber of the controlled irradiant apparatus such that the black panel temperature is maintained between about 100°C and about 110°C until the exposure portions of the sample have been subjected to an exposure of a first total energy radiance. In a preferred embodiment, the exposed portions of the sample are continuously subjected to the light and the sample chamber is held to the specified conditions until the total energy radiance has been received by the exposed portions of the sample.

In the prior art methods of artificial light exposure fading and testing, the dry bulb temperature did not exceed 55°C and the black panel temperature did not exceed 95°C, because it was understood that additional temperatures did not provide additional benefits in accelerating or predicting the fading of materials under artificial light sources. Surprisingly, it has been found in the present invention that the additional temperatures used in the present invention not only produce faster fade times, but the increase in fade time was unexpectedly higher per increase in temperature that was experienced below the 55°C dry bulb temperature and 95°C black panel temperature.

The rate of energy per area that the exposure portions of the sample are subjected to in step 150 in order to achieve the total energy radiance exposure, is preferably selected to minimize the time that the exposure portions are subjected

to the light without causing physical damage to the exposure portions of the sample. The rate of energy per area and the total energy radiance exposure on the exposure portions of a sample can be determined by sampling the rate of energy per area and the total energy radiance exposure on the exposure sample for a particular wave length or wave length band.

In step 160, one of the exposure portions of the sample is removed from the sample chamber for comparison with the reference portion of the sample, which did not experience the fade conditions of steps 140 and 150. In step 170, the exposure portion of the sample from step 160 is analyzed for color value, chroma, or hue, and recorded for comparison with the base point recorded in step 120 from the sample in step 110. In step 180, the analysis results of the reference portion of the sample from step 120 are plotted and compared with the analysis results of the exposure samples from step 170 to determine a trend of the sample material to fade. In step 190, the steps 140 through 180 are repeated on each of the remaining exposure portions of the sample until sufficient data points have been gathered and plotted for determining the fade tendency of the sample material in step 180 with sufficient comfort.

In one example, the test chamber was held at conditions of about 75°C dry bulb temperature, a relative humidity of about 50%, and a black panel temperature of about 102°C. Various fabric samples were mounted in the test chamber and continuosly exposed to a substantially all of the light in the band width of from about 300nm to about 420nm while maintaining the sample chamber conditions.

When measured at a narrow band wave length of about 420nm, the samples were exposed a rate of about 2.2 watts/m2 and were exposed to total levels of radiance of about 436.8 kJ/m2, 655.65 kJ/m2, 873.69 kJ/m2, 1,163.77 kJ/m2, 1,381.9 kJ/m2, 1,600.3 kJ/m2, 1,818.7 kJ/m2, and 2,037.1 kJ/m2.

The procedures of General Motors GM 9538P were applied to samples of the same fabric as in the example. The samples in General Motors test were placed in a test chamber having about the same conditions, subjected to a natural light source, and exposed to about the same levels as the example. (The 1,163.77 kJ/m2 value is approximately 40,000 Langley for hue change.) Although the

fabric samples from the example of the present invention did not demonstrate the same level of fade as the samples from the General Motors test, the samples from the examples of the present invention had a closer correlation to the General Motors tests than samples from other tests under the same conditions, such as the SAE J1885 test. Most surprisingly, was that although the example of the present invention more closely correlated to the General Motors test, the example of the present invention required only six to ten days compared to the three to five months necessary to complete the General Motors test. Therefore, the present invention was able to approximate the more accurate results of the natural radiation source procedures with the speed of the artificial light source procedures.

Although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other versions are possible.

Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions contained herein.