The main function of polyester masterbatch is coloring. Its color and fastness must meet user requirements. At the same time, its quality must also meet the requirements of polyester spinning and post-processing technology, that is, the addition of masterbatch does not affect polyester Spinnability and physical mechanical properties and wearability of colored fibers. For masterbatch manufacturers, testing is a basic estimate of the quality of their products, and for users, it provides a basis for scientific use of masterbatch. The following items should be tested.

1. Appearance. The masterbatch particles are required to be uniform, free of powder, fragments and super-long particles.

2. Bulk density (g/cm). It is required to be stable and accurate, and the particle size should be as consistent as possible with the spinning material slices.

3. Moisture content. Moisture is a very important indicator for polyester spinning. Users generally re-measure the moisture content of the masterbatch before spinning. However, in order to facilitate the user to estimate the amount of additional personnel based on the moisture content of the masterbatch, the masterbatch manufacturer should also detect the moisture content of the product before leaving the factory.

4. Color content. For conventional standard masterbatches such as black, accurate color content is an important basis for users to determine the spinning dilution ratio, while for proprietary masterbatches, the color content is only a reference, and more important is the accurate dilution ratio.

5. Melting point and softening point. The melting point is not an important indicator of the quality of the masterbatch and its spinnability, but it is an important basis for users to determine the spinning and drying process conditions.

6. Discoloration temperature (or heat stability). Whether the masterbatch can adapt to the spinning process is an important basis.

7. Sublimation fastness. Refers to the ability of the pigment in the masterbatch to directly become a gas and escape the carrier due to heat. Due to the different sublimation fastnesses of the dyes, the color tone of the blend may change, and the user's equipment may also be contaminated by the sublimation dyes. This is an index that masterbatch manufacturers must consider when selecting dyes, and it is also an important index to characterize the performance of masterbatch.

8. Color fastness. An important indicator of whether the masterbatch can meet the basic needs of users. But for the coloring before spinning, because each dye must be selected strictly or even very harshly before use, and its dyeing mechanism is to form a uniform solid solution on the surface and the inside, which is stronger than the general conventional dyeing method. Degrees are at least one level higher. Therefore, under normal circumstances, the color fastness of the colored fabric before spinning will not cause any major problems. As long as the masterbatch manufacturer pays attention to accumulating the color fastness data of each dye and each proportion, and has an accurate and reliable basic estimate of the color fastness of the batch of masterbatch, it is not necessary to test this index for every batch.

9. Ash content. This indicator is mainly used to detect the content of inorganic salts and mechanical impurities in the masterbatch, but has no characterization significance for the coarse pigment particles in the masterbatch and the agglomerated particles in the polyester. Practice has proved that the size of ash can predict and characterize the filtration performance of the masterbatch to a certain extent.

10. DF value (or △P curve). It is used to determine the comprehensive actual filtration performance of the masterbatch, and its value can predict the user's spinning component replacement cycle.