TSL0601G Test Criteria for Quality of Color Change Due to Aging

A Toyota engineering standard, “TSL0601G Test criteria for the quality of aging discoloration”, describes a procedure for determining the quality of aging discoloration of automobile interior parts. Aging discoloration is a change in color tone or color caused by sunlight or heat over time.

In general, all exposed interior parts of the car are subject to this assessment. However, in some cases, the range of application may be limited at the discretion of the designer.

The sample to be used in the tests shall be prepared from the product or using the same materials and conditions used for the product. Ceiling surface materials and floor carpet surface materials shall be tested without base material. The sample color shall be determined by reference to the main interior color standard plate issued by the color design department, design development section.

A sample prepared by the method specified in this standard is used for testing under specified conditions. All parts that may cause a color change must meet the criteria shown in the table given in the standard. This criterion is determined as follows:

• Measured color value: 3,0 maximum.
• Visual judgment: Color change grade 4 or better, color fading grade 3 or better.

For those between 2.0 and 3.0, where a noticeable change and fading in color is seen by visual judgment, the range of brightness and hue values ​​is limited as described in this standard. In particular, for hue values, the direction is specified and the standard plate is used as the standard for the direction of color change. That is, it should be within the range covered by plus/minus 45 degree angles along the vector from the center point on the standard plate to the origin of the coordinates.

If the following changes are made during the car development process, the evaluation should be re-conducted:

• Change in part composition: The change occurs not only in the material used for the top surface layer, but also in the backing material, which affects the surface color (for example, changing the urethane used as the dashboard safety pad or changing the adhesive to bond the surface material together).
• Change in material composition (change in the top surface layer) (e.g. changing the resin grade and manufacturer or changing the compounding agent).
• Change in pigment composition (change in pigment composition of the top surface material).

The test methods described in this standard are:

• Method A Ultraviolet carbon arc fademeter: Ultraviolet carbon arc fademeter is used as test equipment. A prepared sample is placed in the holder of the equipment with the ends facing downwards if there is fluff. The irradiated surface of the sample should face the light source. It is necessary to ensure that the irradiated surface does not protrude excessively from the holder. In this case, the sample set is attached to the holder of the ultraviolet carbon arc fademeter and irradiated for the specified time. The sample is removed from the holder and the discoloration or fading is evaluated.
• Method B Xenon lamp: As test equipment, Atlas Ci35, Ci35A or Ci35W is used. A prepared sample is placed in the holder of the test equipment with the tips facing downwards, if there are hairs. The irradiated surface of the sample should face the light source. It is necessary to ensure that the irradiated surface does not protrude excessively from the holder. When the sample is placed in the holder, in this case an ultraviolet filter glass is attached to the irradiated surface and the holder is placed in the test equipment. It is irradiated with the specified amount of ultraviolet light. The sample is removed from the holder and the discoloration or fading is assessed.
• Method C Xenon lamp: Model SC-700FT manufactured by Suga Test Instruments is used as the test equipment. A prepared sample is placed in the holder of the test equipment with the tips of the hairs facing downwards, if any. The irradiated surface of the sample should face the light source. It is necessary to ensure that the irradiated surface does not protrude excessively from the holder. After the sample is placed in the holder, in this case an ultraviolet filter glass is attached to the irradiated surface and the holder is attached to the test equipment. It is then irradiated with the specified amount of light. After the test is completed, the sample is removed from the holder and the discoloration or fading is evaluated.
• Method D Xenon lamp: Model XW-1200 manufactured by Shimazu Corporation is used as the test equipment. A prepared sample is placed in the holder of the test equipment. The irradiated surface of the sample should face the light source. It is necessary to ensure that the irradiated surface of the sample does not protrude excessively from the holder. After the sample is placed in the holder, the holder is placed in the test equipment. The sample is then exposed to the specified amount of ultraviolet light. After the test is completed, the sample is removed from the holder and the discoloration or fading is evaluated.
• Method E Xenon lamp: The Atlas Ci65, Ci65A or Ci4000 is used as the test equipment. A prepared sample is placed in the holder of the test equipment. The irradiated surface of the sample should face the light source. It is necessary to ensure that the irradiated surface of the sample does not protrude excessively from the holder. After the sample is placed in the holder, the holder is placed in the test equipment. The sample is then exposed to the specified amount of ultraviolet light. After the test is completed, the sample is removed from the holder and the discoloration or fading is assessed.
• Method F Xenon lamp: Suga Model SC-700FP is used as the test equipment. A prepared sample is placed in the holder of the test equipment. The irradiated surface of the sample should face the light source. It is necessary to ensure that the irradiated surface of the sample does not protrude excessively from the holder. After the sample is placed in the holder, the holder is placed in the test equipment. The sample is then exposed to the specified amount of ultraviolet light. After the test is completed, the sample is removed from the holder and the discoloration or fading is evaluated.
• Method G Xenon lamp: Suga Model SC-700FP is used as the test equipment. A support is attached to the back of the sample (ABS or PP resin with a thickness of 2 to 4 mm in black color. A prepared sample is placed in the holder of the test equipment. The irradiated surface of the sample should face the light source. It is necessary to ensure that the irradiated surface of the sample does not protrude excessively from the holder. After the sample is placed in the holder, the holder is placed in the test equipment. The sample is then exposed to the specified amount of ultraviolet light. After the test is completed, the sample is removed from the holder and the discoloration or fading is evaluated.
• Method H Xenon lamp: Suga Model SX-75 is used as the test equipment. A prepared sample is placed in the holder of the test equipment. The irradiated surface of the sample should face the light source. It is necessary to ensure that the irradiated surface of the sample does not protrude excessively from the holder. After the sample is placed in the holder, the holder is placed in the test equipment. The sample is then exposed to the specified amount of ultraviolet light. After the test is completed, the sample is removed from the holder and the discoloration or fading is assessed.

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