Mixed-Plastic Polypropylene Blend for Flexible Film Applications

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Solution Overview

Problem

The challenge lies in providing a polypropylene blend suitable for flexible applications that addresses the issues of high contamination levels, dark color, odor, and emissions in recycled materials, which are not adequately addressed by existing purification methods, particularly for film applications.

Innovation Solution

A mixed-plastic polypropylene blend with specific properties, including a density of 900 to 924 kg/m3, a soluble fraction content of 3.0 to 12.0 wt.%, an ethylene-propylene rubber content of less than 7.0 wt.%, an intrinsic viscosity of 1.10 to 1.50 dl/g, and inorganic residues of 0.05 to 3.0 wt.%, is developed through a rigorous recycling process involving sieving, optical sorting, alkaline washing, and Cross Fractionation Chromatography to achieve improved flexibility and quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional purification methods (washing, sieving, aeration) are used on recycled polypropylene, then processing is simplified, but contamination levels remain high and material quality is insufficient for film applications

Engineering Contradiction:

Improvepurification process simplicityVSAvoidmaterial quality for film application

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies parameter changes by precisely controlling the soluble fraction content (3.0-12.0 wt.%) and intrinsic viscosity (1.10-1.50 dl/g) of the polypropylene blend to achieve optimal flexibility and film-forming properties. This quantitative control transforms the material characteristics to meet both processing ease and application quality requirements

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite material system by formulating a mixed-plastic polypropylene blend with specific composition ratios, combining different polypropylene fractions with controlled soluble content and viscosity characteristics. This composite approach enables the material to simultaneously exhibit good processability and high-quality film-forming capabilities

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If recycled polypropylene with high soluble fraction content is used, then flexibility is improved, but material strength and structural integrity deteriorate

Engineering Contradiction:

Improveflexibility for film applicationVSAvoidmaterial strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The patent optimizes the soluble fraction content parameter within the specific range of 3.0-12.0 wt.% to achieve the desired balance. This controlled parameter adjustment ensures sufficient flexibility for film applications while preventing excessive soluble content that would compromise material strength and structural integrity

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the polypropylene blend has low intrinsic viscosity, then processability is improved, but film quality and mechanical properties worsen

Engineering Contradiction:

ImproveprocessabilityVSAvoidfilm quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent precisely controls the intrinsic viscosity parameter within the range of 1.10-1.50 dl/g to achieve optimal balance. This controlled viscosity range ensures good processability and film-forming behavior while maintaining sufficient mechanical properties and film quality, preventing both excessive viscosity (which would hinder processing) and too low viscosity (which would compromise film quality)

Inventive Principle:

Principle #35Parameter changes

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 blend achieves improved flexibility, enabling numerous demanding end-use applications, such as packaging and extruded articles, by effectively reducing contaminants and enhancing material properties.

Implementation Method 1

a soluble fraction (SF) content determined according to CRYSTEX QC analysis in the range from 3.0 to 12.0 wt.-%

Methodology Applied

Scientific EffectDissolution: Solvation

Implementation Method 2

the EPR corresponds to the fraction with a molar mass higher than log M of 3.5 to 8 of the soluble fraction (SF) in TCB at 35° C. obtained by Cross Fractionation Chromatography (CFC) analysis

Methodology Applied

Scientific EffectChromatography: Chromatography