Polyolefin Recycled Material with Stable Tensile Strength
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Solution Overview
Problem
Existing recycled materials from laminated films exhibit a high coefficient of variation in tensile strength after recycling, necessitating improved mechanical strength stability.
Innovation Solution
A recycled material composed of 70% or more polyolefin with a matrix and domains, where the domains have an average area of 0.3 µm² to 10 µm², and a melt-kneading process at temperatures above the adhesive's elastic modulus of 10,000 Pa is used to produce films and sheets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a laminated film including different resins (nylon, PET, polyethylene) is used for packaging, then the film achieves various functional requirements (barrier, strength, sealability), but separation and collection during recycling become difficult
Solution Approach 1:
The adhesive layer is extracted and identified as the key component preventing resin separation. By targeting the adhesive layer for selective removal through melt-kneading, the patent enables separation of the adhesive from the resin layers, facilitating subsequent recycling of the resins.
Solution Approach 2:
The patent changes the temperature parameter during melt-kneading to above the adhesive's glass transition temperature, altering the adhesive's physical state from rigid to flexible. This parameter change enables the adhesive to be selectively removed while preserving the resin layers.
2Productivity
If the adhesive layer is not properly removed during recycling, then the recycled material can be produced efficiently, but the tensile strength and mechanical stability of the recycled material deteriorate
Solution Approach 1:
The patent replaces mechanical separation methods with a thermal-field-based melt-kneading process. By using temperature control above the adhesive's glass transition temperature, the adhesive is selectively softened and removed, achieving both high recycling efficiency and preserved tensile strength in the recycled material.
3Reliability
If the melt-kneading temperature is too high, then the adhesive layer is effectively removed, but the resin structure may be damaged and mechanical strength stability decreases
Solution Approach 1:
The patent precisely controls the melt-kneading temperature parameter to be above the adhesive's glass transition temperature but below the degradation temperature of the resins. This optimized parameter range enables effective adhesive removal while preserving resin integrity and mechanical strength stability.
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 solution results in a recycled material with a low coefficient of variation in tensile strength, enhancing mechanical stability and processability.
Implementation Method 1
a melt-kneading process at temperatures above the adhesive's elastic modulus of 10,000 Pa
Data Source
Figure 1~2B
AI summary
The present invention provides: a recycled material that has a relatively low variation coefficient of the tensile strength at break (%), which is a mechanical strength, after recycling; a film and a sheet, each of which uses this recycled material; and a method for producing this recycled material. A recycled material according to the present invention comprises 70% by mass or more of a polyolefin; in a cross-section of a recycled article that is formed of this recycled material, there are a matrix, which is mainly composed of the polyolefin, and domains; and the average area of the domains is 0.3 µm2 to 10 µm2.