Polypropylene Expanded Beads With Recycled Resin for Stable Foaming
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Solution Overview
Problem
Existing methods for producing expanded beads using recovered polypropylene-based resins result in variations in expansion ratio and reduced closed cell ratio, leading to appearance defects in the molded articles.
Innovation Solution
A method involving a mixture of polypropylene-based resin A (non-recovered) and resin B (recovered post-consumer material) with specific melting point and melting point difference, ash content, and Tme−Tms difference, impregnated with a blowing agent and expanded under controlled pressure to achieve consistent expansion and high closed cell ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If recovered polypropylene-based resin is used as base material, then environmental sustainability is improved, but expansion ratio consistency deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the melting point difference between resin A and resin B (10-30°C) and the blending ratio (resin A: 40-97 wt%, resin B: 3-60 wt%). This controlled parameter variation allows the use of recovered resin while maintaining consistent expansion ratio, as the specific melting point gradient ensures uniform melting and expansion behavior during the foaming process.
Solution Approach 2:
The patent uses composite materials by combining two different polypropylene-based resins with distinct melting points. resin A (melting point 130-155°C) and resin B (melting point 140-185°C) are blended to create a composite base material that leverages the properties of both resins, achieving both sustainability and expansion consistency.
2Reliability
If recovered polypropylene-based resin is used as base material, then environmental sustainability is improved, but closed cell ratio deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the melting point difference (10-30°C) and ash content (≤5 wt%) of the recovered resin. These parameter constraints ensure that the recovered resin B does not contain excessive impurities that would interfere with cell closure, while still maintaining high sustainability through effective waste material utilization.
3Reliability
If mixture of recovered and non-recovered resin is used, then sustainability is improved, but appearance quality deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the melting point difference (10-30°C) between the two resins and the blending ratio. This ensures uniform melting and expansion during foaming, preventing appearance defects such as surface irregularities or inconsistent cell structure, thereby maintaining high appearance quality while utilizing recovered materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method produces expanded beads with reduced variation in expansion ratio and improved appearance, facilitating effective utilization of recycled materials and contributing to environmental sustainability.
Implementation Method 1
releasing the polypropylene-based resin beads containing the blowing agent from the sealed vessel together with the aqueous medium under a pressure lower than in the sealed vessel to foam the polypropylene-based resin beads
Implementation Method 2
releasing the polypropylene-based resin beads containing the blowing agent from the sealed vessel together with the aqueous medium under a pressure lower than in the sealed vessel to foam the polypropylene-based resin beads
Implementation Method 3
the polypropylene-based resin beads contain, as a base material resin, a mixture of a polypropylene-based resin A having a melting point of 130° C. or higher and 155° C. or lower and a polypropylene-based resin B
Data Source
AI summary
A method for producing expanded beads using a mixture of a polypropylene-based resin A that is a non-recovered material and polypropylene-based resin B that is a recovered product of a post-consumer material. The method enables production of expanded beads wherein variation in the expansion ratio and reduction in the closed cell ratio are inhibited, and is capable of improving the appearance of a molded article. A base material resin, a mixture of resin A having a melting point 130-155° C. and resin B is used, the blending rate of A is 40 −97 wt %, and B is 3 −60 wt %, the melting point difference between the resins is 10-30° C., resin B has an ash content of 5 wt % or less, and in a melting peak observed in a DSC curve in heat-flux differential scanning calorimetry, the difference between an extrapolated melting start and end temperature is 30° C. or more.