Nucleating agent master batches used for foaming of thermoplastic resin

Abstract

The invention relates to a nucleating agent and a method for preparing the nucleating agent, wherein the nucleating agent is used for reducing the dimension of the foaming hole and improving the density of the foaming hole when a supercritical fluid foaming agent (such as carbon dioxide or nitrogen) is used for producing thermoplastic foaming products. The raw materials of the nucleating agent mainly consists of an organic montmorillonite, a thermoplastic resin and a supercritical fluid foaming agent; the specific weight of the nucleating agent master batches is controlled within 100+/-5% of that of the thermoplastic resin. The method has the advantages that a supercritical fluid foaming method is adopted to prepare the nucleating agent master batches which have approximate specific weights to the resin material adopted by the subsequent foam forming, thus facilitating the subsequent injection foam forming and extrusion foam forming; and the carbon dioxide or nitrogen in supercritical state is used for reducing the viscosity of the carrier resin during the mixing process, the dispersion uniformity of the peeled sandwich montmorillonite in the carrier resin is reinforced, the process temperature is reduced, the layer spacing of the sandwich nano-montmorillonite which may be not peeled is increased and the sufficient peeling is realized.

Description

technical field [0001] The invention relates to a nucleating agent used for reducing cell size and increasing cell density when supercritical fluid foaming agent (such as carbon dioxide or nitrogen) is used to produce thermoplastic foam products and a manufacturing method of the nucleating agent. technical background [0002] When foaming polymers, especially supercritical fluids, such as nitrogen or carbon dioxide, are used as foaming agents. Nitrogen or carbon dioxide will dissolve in the polymer melt to form a single-phase solution. In injection molding, extrusion molding or blow molding of high cell density and fine cell material products, it is necessary to form a large number of nucleation sites in the melt during the molding process, otherwise it is easy to cause large cells and uneven sizes . The formation of a large number of nucleation sites from such single-phase solutions requires the generation of enormous thermodynamic instabilities, such as rapid temperature ...

AI Technical Summary

Problems solved by technology

However, the particle size of these organically treated montmorillonites is still at the micron level, and it is an intercalated structure. During the plasticization and mixing process in the molding machine, it cannot form fully exfoliated and dispersed nano-montmorillonite sheets and cannot form microscopic montmorillonite sheets. The large number of nucleation sites required for cell foaming will not improve the performance of materials or products; on the contrary, due to uneven dispersion, it will cause uneven cells and weak performance points in materials or products

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