Method for processing in-situ dyed TPU (thermoplastic polyurethane) foam beads

Abstract

The invention discloses a method for processing in-situ dyed TPU (thermoplastic polyurethane) foam beads. The method includes steps of 1, placing disperse dye powder, dispersing auxiliaries and TPU particles in a stirring machine, rotationally stirring the disperse dye powder, the dispersing auxiliaries and the TPU particles and uniformly adsorbing the dye powder and the dispersing auxiliaries on the outer surfaces of the TPU particles; 2, placing the treated TPU particles in a high-pressure vessel, injecting high-pressure fluid into the high-pressure vessel until the temperatures and the pressures of the high-pressure vessel reach preset temperatures and pressures, continuously diffusing disperse dye molecules into the TPU particles under entrainment effects of supercritical high-pressure fluid, allowing the disperse dye molecules to gradually reach dye concentration balance, carrying out in-situ dyeing on the TPU particles and allowing the high-pressure fluid to reach solubility balance in the TPU particles; 3, opening an exhaust valve of the high-pressure vessel, quickly releasing the pressures and expanding and foaming the dyed TPU particles; 4, washing dye and dispersing agents on the outer surfaces of the colored TPU foam particles taken out of the high-pressure vessel and carrying out drying treatment to obtain colored TPU foam particle materials. The method has the advantages that working procedures can be saved, the efficiency can be improved, and foam particles are excellent in performance.

Description

technical field [0001] The invention relates to the field of colored TPU foam beads, in particular to a processing method for in-situ dyeing of TPU foam beads, by making organic pigments physically adsorbed on the outer surface of TPU particles diffuse into the TPU in a supercritical fluid atmosphere Inside the resin matrix, the in-situ dyeing of TPU particles is realized, and the preparation of colored TPU particles is realized by quickly releasing the pressure of the supercritical fluid. Background technique [0002] TPU has many advantages such as high wear resistance, high elasticity, fatigue resistance, and chemical corrosion resistance, so it is widely used in shoe materials. The colored low-density foaming material prepared with TPU as the base material is expected to replace the EVA material foaming material in the field of high-performance shoe materials. [0003] The method of preparing TPU foam material by chemical blowing agent is known. Adding appropriate pigm...

AI Technical Summary

Problems solved by technology

[0006] 1. The dye is basically a solid color masterbatch. No matter how small the solid color masterbatch is, it is impossible to mix it with the TPU resin to reach the molecular level. During the foaming of the TPU resin and the formation of TPU foam beads, These solid color masterbatches are not enlarged synchronously, so that cells are formed between the solid color masterbatch and the TPU foamed beads, which in turn affects the final performance of the colored TPU foamed beads;

[0007] 2. At present, in the molding process of colored TPU foam beads, there are two steps that are independent of each other and carried out successively, that is, two steps of dyeing and foaming. For example, firstly, the color masterbatch and TPU resin are fully mixed and mixed evenly. Then use a screw extruder to form TPU resin particles with color masterbatch, and then perform foaming operation on the formed particles. The above two independent steps are more complicated in process and reduce production efficiency.