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A pressurized fluid-assisted foaming injection molding process

An injection molding process and auxiliary foaming technology, which is applied in the field of plastic molding and processing, can solve the problems of poor mechanical properties of foamed plastic parts, less product weight loss, and decreased molding efficiency, and achieve the effect of high porosity and excellent mechanical properties.

Active Publication Date: 2019-06-14
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantages of this process are: (1) two sets of molding molds are required, resulting in increased costs; (2) many processes, long and cumbersome operation procedures, resulting in a decrease in molding efficiency; (3) it is difficult to ensure the appearance and shape of foamed plastic parts size
However, the process and the mold also have some obvious technical defects: (1) the process is complex, the control is difficult, and the process is unstable; (2) the structure of the mold is complex and requires high-pressure sealing; (3) it is difficult to realize the method of injecting gas Effective control of the foaming space leads to uneven foaming; (4) The process and mold are difficult to apply to thin-walled plastic parts
[0008] Chinese patent CN 106541540 A discloses a microporous foamed part with a decorative outer film and a processing method. The method solves the surface problems of conventional foamed plastic parts by covering the surface of the microporous foamed part with a decorative outer film. Quality problems, but the operation of this method is relatively complicated, resulting in high processing costs, and it cannot solve the poor mechanical properties of foamed plastic parts caused by poor cell structure and the limited foaming space in the conventional foam injection molding process. The resulting product weight loss and other issues
The disadvantage of this method is that it needs to be equipped with special two-color or multi-color foam injection molding equipment, and the weight loss of foamed products is very limited
The disadvantage of this method is that a special injection mold needs to be specially designed, and special injection molding equipment is required. In addition, this method does not solve the problem of the appearance quality of foamed plastic parts

Method used

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  • A pressurized fluid-assisted foaming injection molding process
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  • A pressurized fluid-assisted foaming injection molding process

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0057] The raw material is polypropylene, and its melt index and density are 20g / 10min (@220℃ / 10kg), 0.91g / cm 3 (@23°C); the foaming agent is nitrogen with a purity of 99.5%; the pressure fluid is nitrogen with a purity of 98%, and its maximum pressure can reach 40MPa. The foaming injection molding process is divided into two groups, the first group adopts the conventional foaming injection molding process and method, and the second group adopts the pressurized fluid-assisted foaming injection molding process and method proposed by the present invention.

[0058] In the first group of experiments, the barrel temperature of the injection molding machine was set to 60°C-160°C-210°C-220°C-220°C-220°C from the barrel to the nozzle, the mold temperature was set to 40°C, and the injection speed was set to 80mm / s, the cooling time is set to 25s, and the injection volume is 45cm 3 , The pumping amount is 0.3% (weight content). In the second set of experiments, the barrel temperatur...

Embodiment 2

[0064] The raw material is polystyrene, its melt index and density are 10g / 10min(@220℃ / 10kg), 1.02g / cm 3 (@23°C); the foaming agent is nitrogen with a purity of 99.5%; the pressure fluid is nitrogen with a purity of 98%, and its maximum pressure can reach 40MPa. The foam injection molding process experiment is divided into two groups, the first group adopts the conventional foam injection molding process, and the second group adopts the pressurized fluid-assisted foam injection molding process and method proposed by the present invention. In the first group of experiments, the barrel temperature of the injection molding machine was set to 60°C-170°C-220°C-230°C-230°C-230°C from the barrel to the nozzle, the mold temperature was set to 60°C, and the injection speed was set to 60mm / s, the cooling time is set to 25s, and the injection volume is 42cm 3 , The pumping amount is 0.4% (weight content). In the second set of experiments, the barrel temperature of the injection moldin...

Embodiment 3

[0069] The raw material is polylactic acid, its melt index and density are 18g / 10min(@220℃ / 10kg), 1.24g / cm 3 (@23°C); the foaming agent is nitrogen with a purity of 99.5%; the pressure fluid is nitrogen with a purity of 98%, and its maximum pressure can reach 40MPa. The foam injection molding process experiment was divided into two groups. The first group used the conventional foam injection molding process and method, and the second group adopted the pressure fluid-assisted foam injection molding process and method proposed by the present invention. In the first group of experiments, the barrel temperature of the injection molding machine was set to 60°C-140°C-150°C-160°C-170°C-170°C sequentially from the barrel to the nozzle, the mold temperature was set to 25°C, and the injection speed was set to 40mm / s, the cooling time is set to 30s, and the injection volume is 45cm 3 , The pumping amount is 0.35% (weight content). In the second set of experiments, the barrel temperatu...

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Abstract

The invention discloses a pressure fluid auxiliary foaming injection molding process, solves the problems of multiple problems in foaming and injection molding, low porosity of foamed products and lower weight reduction in the prior art, and achieves the beneficial effects of capability of preparing foamed injection products with excellent appearance quality, excellent mechanical performance and prominent weight reduction. In the pressure fluid auxiliary foaming injection molding process, a first fluid with a preset pressure is prefilled in a molding cavity of a mold for inhibiting foaming inthe flowing process and reducing the loss of a foaming agent filled in the flowing process.

Description

technical field [0001] The invention relates to the technical field of plastic forming processing, in particular to a pressurized fluid-assisted foaming injection molding process. Background technique [0002] Porous plastic products have the characteristics of material saving, light weight, energy absorption, high specific strength, large specific surface area, and excellent heat insulation performance. They are widely used in packaging, automotive interior parts, sports equipment, building materials, biomedicine, and molecular filtration. devices and other fields. Foam injection molding is a major molding technique for preparing porous plastic products. Compared with extrusion foaming, molded foaming, kettle pressure foaming and other technologies, foaming injection molding has technical advantages such as high molding efficiency, high degree of automation, high design flexibility, and direct molding of products with three-dimensional complex structures. It is considered...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B29C45/17B29C44/42
CPCB29C44/42B29C45/0025B29C45/1704B29C45/1706B29C2045/1707B29C2045/1715
Inventor 王桂龙赵国群侯俊吉董桂伟
Owner SHANDONG UNIV