Thin-wall micro-foaming material and preparation method thereof

Abstract

The invention discloses a thin-walled micro-foaming material, which comprises the following components according to the weight percentage of raw materials: 30-50% of polypropylene, 5-20% of vinyl elastomer, 20-50% of high-melt index masterbatch, 2 fillers ~10%, functional mixing aid 1~3%, antioxidant 0.2~0.6%, foaming agent 0.5~3%. In the present invention, through the optimization of raw material components and their proportions, the addition of high-melt index masterbatch improves the mold filling ability of the material, and the addition of functional mixing aids improves the decomposition speed of the blowing agent. At the same time, the added vinyl elastomer has The non-crystallization feature reduces the cooling rate of the melt, increases the time for bubble nucleation and cell growth, and makes the dense surface layer formed by foaming thinner and the foaming core layer thicker, that is, the micro-foaming material is realized. Thin-walled foam, which has a significant weight reduction effect and avoids apparent defects after injection molding due to poor filling ability of the material.

Description

technical field [0001] The invention relates to the field of modified polymer materials, in particular to a thin-walled foam material and a preparation method thereof. Background technique [0002] Driven by the trend of lightweight automobiles, micro-foamed materials are made into air-filled composite materials with a dense surface layer and a foamed core structure through the nucleation and foaming of foaming agents, which has the advantage of low density and has a significant weight-loss effect. . However, micro-foamed polypropylene prepared by chemical foaming generally has appearance problems such as air marks, material flowers and even peeling and delamination during the injection molding process. The solution usually used in the prior art is to prefill the mold cavity Back-pressure gas, and the use of secondary mold opening technology in order to increase the weight reduction ratio, but these will greatly increase the investment cost of injection molding equipment an...

AI Technical Summary

Problems solved by technology

However, micro-foamed polypropylene prepared by chemical foaming generally has appearance problems such as air marks, material flowers and even peeling and delamination during the injection molding process. The solution usually used in the prior art is to prefill the mold cavity Back pressure gas, and the use of secondary mold opening technology in order to increase the weight reduction ratio, but these will greatly increase the investment cost of injection molding equipment and molds, and the overall cost reduction is not obvious enough

In addition, while high foaming ratio brings light weight, it will also cause serious attenuation of the mechanical properties of the material. The thickness of the secondary molded part is above 3.0mm, and the thickness of the part is relatively large. In order to maintain the performance of the part Result in limited overall weight loss

[0003] At present, the wall thickness of the mainstream micro-foamed products is about 2.5-3.0 mm. Due to the influence of the dense surface layer on the structure of the micro-foamed material that does not have the effect of reducing weight, at the dense surface layer, the speed of foaming and nucleation is low. Due to the cooling speed of the melt, the dense surface layer does not foam, and reducing the wall thickness will result in a decrease in the thickness of the foam core layer, which eventually leads to a decrease in the weight of the material and a decrease in the specific gravity

At the same time, reducing the thickness of the part will make it difficult to fill the melt, and the pressure of the melt will drop seriously, resulting in apparent defects such as lack of glue, flow marks, and material flowers.

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