Fibrous resin thin-wall product and production method thereof

Abstract

The invention relates to an injection molding product, in particular to a fibrous resin thin-wall product with the fiber content of 20%-50% and a production method thereof. The wall thickness of the product is 0.8-1.5 mm, and one or / and more surfaces of the product are provided with a non-fibrous resin surface layer with the thickness of 1-20 micrometers. In the production method, supercritical nitrogen or carbon dioxide is used as a plasticizer, the surface temperature of a mould cavity is raised before injection so that the fluidity is further improved, and the surface of the mould cavity is cooled to a lower temperature after injection, thereby a lighter and thinner product is obtained; and the product has the advantages of favorable apparent quality, high strength and high size stability.

Description

technical field [0001] The invention relates to an injection molding product, in particular to a thermoplastic resin thin-walled product with a fiber content of 20-50% and an injection molding method. Background technique [0002] Driven by the knowledge economy and the information age in the 21st century, thin-walled plastic parts have been more and more widely used in office equipment, communications, electronics, instruments, audio-visual, medical and other fields. Warpage puts forward higher requirements. Adding reinforcing fibers to polymers, such as glass fibers, can increase product strength, rigidity, hardness, etc., increase its heat resistance and heat distortion temperature, improve dimensional stability, reduce shrinkage, and reduce creep. However, the higher the fiber content in the polymer, the lower the fill flow of the material. When injection molding thin-walled parts, very high injection pressures are required to achieve cavity filling. Too high injectio...

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Problems solved by technology

Although the fluidity of the melt can be improved by adding supercritical nitrogen or carbon dioxide to the melt, there are still the following problems: as the fiber content increases, the effect will gradually decrease; When the molten material is injected, the surface temperature of the mold cavity is relatively low. During the process of filling the molten material, the product layer in contact with the cavity surface is rapidly cooled to form a solidified layer, which reduces the passing area when the molten material is filled. For thin-walled products with a large area, not only the filling time is significantly increased and the injection pressure is increased, but also the residual stress in the product is more uneven, and the warping deformation after molding is increased; under high injection pressure, the reinforcing fiber It is very easy to form floating fibers on the surface of the product, which seriously affects the appearance of the product and the spraying operation; after the molten material is injected into the mold cavity, due to thermodynamic instability, the dissolved gas will precipitate and foam at the front end of the flow peak, and the front end of the flow peak The remaining pits after the cell rupture will also be frozen by the lower temperature cavity surface, forming foaming marks on the surface of the product and affecting the subsequent surface treatment

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