Color Difference

The fiber colors of different spinning positions or the same spinning position at different time periods are inconsistent, and the fabric shows surface color difference or stripes after dyeing. The root causes of spinning color difference include uneven masterbatch metering, changes in colorant thermal stability caused by spinning temperature fluctuations, and color differences between chip batches. Color difference is most obvious in dark and sensitive colors (such as navy blue, coffee), and is the primary control indicator of textile appearance quality.

1. Equipment factor: uneven masterbatch addition (uneven masterbatch mixing or low metering pump control accuracy). 2. Comprehensive factor: spinning temperature fluctuations cause thermal stability changes of the colorant. 3. Comprehensive factor: differences in residence time of the spinning components. 4. Material/formulation factor: color differences between different batches of chips. 5. Cooling air field factor: the temperature, wind speed and uniformity of the side-blowing air or ring-blowing air determine the solidification and forming quality of the fiber — too fast cooling leads to rough surface and increased internal stress, uneven cooling leads to inconsistent thickness of individual filaments in the same bundle, and low wind speed leads to filament sticking and filament breakage; the air field parameters need to be precisely controlled.

1. Process parameter optimization and adjustment: enhance the uniformity of masterbatch mixing and distribution. 2. Mold/tooling improvement and maintenance: precisely regulate the metering addition pump. 3. Equipment inspection and system maintenance: stabilize the spinning temperature. 4. Material/formulation optimization: control the color stability of chip batches. 6. Preventive management: establish standardized process parameter cards and quality control limits for each mold/product, and regularly conduct process capability index (CPK) evaluations. For recurring problems, use fishbone diagrams or the 5Why analysis method to trace the root cause, and solidify the countermeasures as PFMEA control points. Establish a regular equipment maintenance system, and implement life management for key tooling such as dies/spinnerets/calender rolls/coating heads.

This problem is a typical manifestation of color difference in melt spinning. The core of the solution lies in the precise stability of the spinning temperature, the high-precision control of metering supply, and the optimized maintenance of the spinneret/cooling air field. It is recommended to start from chip quality and spinning parameters, and gradually troubleshoot to the equipment and component level.