Excellent-appearance chemical foaming injection molding process

An injection molding process and chemical foaming technology, applied in the field of plastic chemical foaming, to achieve the effects of simple and controllable injection molding foaming process, reduced product cost and good appearance quality

Active Publication Date: 2017-07-28
CHANGCHUN FAWAY ADIENT AUTOMOTIVE SYST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The object of the present invention is to provide a chemical injection molding foaming method, through the rational allocation of raw materials and the process improvement of the foaming process, so as to obtai

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] 1. Allocation of raw materials

[0021] Take the PP modified material, dry it at 95°C for 4-5 hours, add 0.8% by weight white mineral oil to the dried PP modified material, then add 0.5% by weight foaming agent, mechanically mix Stirring machine, fully and evenly mixed;

[0022] 2. Injection molding

[0023] 1. Injection molding: inject the above-mentioned uniformly mixed raw materials into the feeding barrel of the injection molding machine, set the barrel temperature of the injection molding machine at 210°C~240°C, cancel the screw ejection during the plasticization process; set the back pressure value to 12bar, Control the foaming agent in the melt in the barrel to be in a pre-foaming state, and the ungrown bubble nuclei are evenly distributed in the melt in the pre-foaming state; then use a supercharger to increase the injection speed and injection volume, so that The injection action is completed within 1.5s;

[0024] 2. Foam molding: After the melt fills the mo...

Embodiment 2

[0028] 1. Allocation of raw materials

[0029] Take the PP modified material, dry it at 95°C for 4-5 hours, add 0.8% by weight white mineral oil to the dried PP modified material, then add 0.6% by weight foaming agent, mechanically mix Stirring machine, fully and evenly mixed;

[0030] 2. Injection molding

[0031] Same as Example 1, the difference is that the back pressure value is set at 14 bar according to the product weight and the foaming agent addition ratio.

[0032] Result: There is no effect on the product quality of large skin texture products (skin texture size is greater than 1mm²); for small skin texture products (skin texture size is less than 1mm²), air marks may appear on the product surface, affecting product quality, and the product weight reduction ratio reaches 7%. In JF03-1301-1-2010 light resistance test, the result is qualified.

Embodiment 3

[0034] 1. Allocation of raw materials

[0035] Take the PP modified material, dry it at 95°C for 4-5 hours, add 0.8% by weight white mineral oil to the dried PP modified material, then add 0.3% by weight foaming agent, mechanically mix Stirring machine, fully and evenly mixed;

[0036] 2. Injection molding

[0037] Same as Example 1, the difference is that the back pressure value is set at 8 bar according to the product weight and the foaming agent addition ratio.

[0038] Results: Lightweight chemical foaming injection molding parts with no obvious air marks on the appearance and pores inside the product were obtained. This solution is suitable for all skin texture injection molding parts, but the weight reduction ratio of the product is 4%. In JF03-1301-1-2010 light resistance test, the result is qualified.

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PUM

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Abstract

The invention relates to an excellent-appearance chemical foaming injection molding process. The process comprises the following steps: (1) 0.5-1% of white mineral oil and 0.3-0.7% of a foaming agent are added in a PP modified material for full and uniform mixing; and (2) the uniformly-mixed raw materials are injected in an unloading barrel of an injection molding machine; the temperature of a charging barrel of the injection molding machine is set within 210-240 DEG C; the screw rod injection retreating is omitted in the plastifying process; a back pressure value is set according to the product weight and the adding ratio of the foaming agent; the injecting speed and the injecting quantity are increased by using a supercharger, so that the injecting action is finished within 1.5 s; the mold surface temperature is controlled within 35-50 DEG C; and after the product is totally cooled, the product is taken out after mold opening. An injection molding part prepared by the process is excellent in appearance quality, and has no air marks on the surface.

Description

technical field [0001] The invention belongs to the field of chemical foaming of plastics, and in particular relates to a chemical foaming injection molding process with good appearance quality of injection molding products. Background technique [0002] Compared with unfoamed materials, the density of foamed plastics can be reduced by 5% to 95%, thereby reducing raw material consumption and cost. At the same time, it has the advantages of good sound insulation and heat insulation performance, shock load absorption, good cushioning performance, and low price. Therefore, foamed plastics are widely used in the automotive industry. [0003] At present, the technology of microcellular foaming mainly focuses on intermittent autoclave pressure foaming, molded foaming, physical foaming injection molding process and chemical injection foaming. Due to the short molding cycle and high production efficiency of the chemical foaming injection molding process, it can form microcellular f...

Claims

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Application Information

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IPC IPC(8): B29C44/34B29C44/42B29C44/60B29L31/30B29K23/00
CPCB29C44/3446B29C44/42B29C44/60B29K2023/12B29L2031/3005
Inventor 刁鹏鹤唐永亮李洪江杨斌
Owner CHANGCHUN FAWAY ADIENT AUTOMOTIVE SYST CO LTD
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