Many plastic products fade in a long time outdoors or in a place exposed to direct sunlight. What is the reason and how to test

2019-12-04 16:32:28


Many plastic products fade in a long time outdoors or in a place exposed to direct sunlight. What is the reason and how to test?

This is related to the weather ability of the color masterbatch used for plastic products. The light resistance is poor. The color fades in a long time under direct sunlight. How to test it? In this section, we will talk about the weather resistance test method of the color masterbatch:

The first is the selection of the exposure site. The exposure test should preferably be performed in a professionally qualified exposure site, or you can choose to set up a nearby exposure site to arrange the test. If it is a self-provided site and equipment for the exposure test, the site, equipment, etc. should meet the requirements of the specification as much as possible, that is, the exposure rack should be placed in non-residential and non-industrial areas, the dust content in the air should be low, and it should be far from the pollution of automobile exhaust gas; The location of the exposure rack should ensure that the shadows of surrounding objects will not fall on the exposed test specimens during the sunlight time; the structure of the exposure rack requires that the test specimens can be firmly fixed and the air on the back of the specimens can flow freely.

The exposure rack faces south, and the inclination angle with the horizon is equal to the latitude of the exposure site.

When the exposure is in progress, it is better to equip the environment monitoring equipment near the exposure rack in order to record the environmental temperature (highest and lowest daily), relative humidity (highest and lowest daily), rainfall time, and total humidification time (rain And dew), total radiant energy and ultraviolet radiant energy (whether broadband or narrowband) and the relative humidity at the same exposure angle of the sample (highest and lowest daily). In this way, the environmental conditions around the exposure rack can be well tested, and the recorded data can be used as part of the test results to complete the test data.

The angle of the sample of the color fastness test of the masterbatch in the natural environment. When it is irradiated outdoors, the angle of the sample determines the energy of sunlight radiation, and it also affects the temperature of the sample and the time it is wet. The angle of the template depends on the use of plastic products.

The color masterbatch is tested and evaluated for weathering fastness under the natural environment. The samples are placed on an exposure rack and exposed for 24 hours each day. The exposure period is determined by the required service life of the test specimen. Pay attention to the change of the sample. When the specified time of the test is reached or the change of the sample has reached the minimum allowable level, the test is ended and the evaluation phase is entered.

According to the color change standard sample card (GB250), a 5-level system: 5 is the best, and 1 is the worst.

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