Thermoplastic polyurethane foam particles and preparation method thereof

Abstract

The invention belongs to the technical field of foam materials, and provides thermoplastic polyurethane foam particles and a preparation method thereof. The thermoplastic polyurethane foam particles are prepared by adopting the following components, in percentages by weight, wherein each component is used based on 100 wt% of a total weight of the raw materials: 60-95 wt% of a thermoplastic polyurethane elastomer, 5-40 wt% of a second polymer, and 0-5 wt% of a foam nucleating agent; and the preparation method comprises the following steps: (1) mixing the components in the raw materials, and performing granulation to obtain thermoplastic polyurethane blended alloy particles; and (2) performing forming on the obtained thermoplastic polyurethane blended alloy particles by using supercritical carbon dioxide foaming to prepare the thermoplastic polyurethane foam particles. According to the preparation method provided by the invention, the thermoplastic polyurethane foam particles prepared bythe method have a low shrinkage ratio, good dimensional stability, and a full appearance while maintaining excellent mechanical properties.

Description

technical field [0001] The invention belongs to the technical field of foaming materials, and in particular relates to a thermoplastic polyurethane foaming particle and a preparation method thereof. Background technique [0002] Foamed materials have low density, high specific strength, heat and sound insulation and cushioning properties, and are widely used in packaging, industry, agriculture, transportation, military, aerospace, and daily and civilian products. Commonly used foaming materials include polystyrene (PS) foam, polyethylene (PE) foam, polypropylene (PP) foam, and polyurethane (PU) soft and rigid foams. Or chemically fill a large number of air bubbles inside the plastic. [0003] Thermoplastic polyurethane (TPU) has the advantages of good physical and mechanical properties, low temperature flexibility, hydrolysis resistance, aging resistance, environmental friendliness, and recyclability. In addition to the excellent performance of the material, it also has ex...

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Problems solved by technology

The process and equipment of this method are complicated, and at the same time, the TPU base material needs to be boiled and soaked in water, which will easily lead to material degradation and affect its mechanical properties

[0008] Chinese patent document CN103951965 discloses a preparation method of colored TPU foaming material, using supercritical carbon dioxide as a physical foaming agent, one-step foaming by water bath or steam, second foaming by hot air, and finally by high-pressure air or Nitrogen is foamed three times to prepare foamed materials. The process and equipment of this method are complicated and the cost is high

[0009] Chinese patent documents CN103709726 and CN104385479 disclose a method for preparing TPU expanded particles by continuous extrusion foaming with supercritical fluid as a physical foaming agent and inorganic filler as a nucleating agent. However, in the melt state, The viscosity and strength of TPU are relatively reduced, which makes it difficult to control the cell structure of the foamed material, and the cell size is large and easy to shrink

This severe shrinkage not only significantly increases the density of the foamed material, but also causes obvious wrinkles and depressions on the surface of the foamed material, and the appearance is dry, which seriously affects the subsequent use of the foamed material.

[0011] Chinese patent documents CN103642200 and CN103804889 adjust the cell size and shrinkage by introducing a cell size stabilizer and a melt viscosity regulator, but the effect is still not ideal. Cooking, and TPU resin, especially polyester TPU resin, is easy to hydrolyze, and long-term boiling will easily lead to its degradation and yellowing

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