Polymer Composition for Impact-Resistant Transparent Containers

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Solution Overview

Problem

Current polymer compositions for containers storing potable liquids lack a balance of impact strength, melt strength, and optical properties while ensuring chemical inertness, which is crucial for compliance with stringent public health regulations and aesthetic appeal.

Innovation Solution

A polymer composition comprising 30.0% to 95.0% propylene-based polymer, 5.0% to 65.0% ethylene-based polymer, and 0.5% to 10.0% polystyrene-poly(ethylene-propylene) block copolymer, optimized for improved impact resistance, melt strength, and transparency, achieved through specific weight ratios and processing conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polyolefin materials are used to ensure chemical inertness and compliance with public health regulations, then chemical inertness is improved, but impact strength and optical properties deteriorate

Engineering Contradiction:
Improvechemical inertnessVSAvoidimpact strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention uses a composite polymer composition consisting of polyethylene (5-65 wt%), polypropylene (30-65 wt%), and polystyrene-polyethylene-propylene block copolymer (5-20 wt%). This multi-component composite system combines the chemical inertness of polyolefins with the impact strength and optical properties provided by the block copolymer, resolving the contradiction between reliability and strength.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The polystyrene-polyethylene-propylene block copolymer acts as an intermediary component that bridges the polyethylene and polypropylene phases. It improves interfacial adhesion between the polyolefin matrices, enhances impact strength through rubber-toughening mechanisms, and maintains chemical inertness while providing the necessary mechanical and optical properties.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If polyolefin materials are used to ensure chemical inertness, then public health compliance is improved, but transparency and optical properties deteriorate

Engineering Contradiction:
Improvepublic health complianceVSAvoidtransparency
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The transparent composite is achieved by carefully selecting the polyethylene and polypropylene components and their ratios, combined with the block copolymer. The specific composition range (5-65 wt% polyethylene, 30-65 wt% polypropylene, 5-20 wt% block copolymer) creates a homogeneous microstructure that allows light transmission while maintaining chemical inertness for public health compliance.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If conventional polymer compositions are used, then ease of manufacture is maintained, but the balance of impact strength, melt strength, and optical properties deteriorates

Engineering Contradiction:
ImproveprocessabilityVSAvoidimpact strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The invention optimizes the compositional parameters within specific ranges: polyethylene (5-65 wt%), polypropylene (30-65 wt%), and block copolymer (5-20 wt%). These parameter adjustments enable the composition to maintain good processability through conventional extrusion and blow molding while achieving superior impact strength and optical properties that conventional compositions cannot provide.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If conventional polymer compositions are used, then ease of manufacture is maintained, but melt strength deteriorates

Engineering Contradiction:
ImproveprocessabilityVSAvoidmelt strength
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The block copolymer component (5-20 wt%) serves as a melt strength enhancer. Its triblock structure provides thermal and rheological stability during processing, allowing the composition to maintain form stability during extrusion and blow molding operations. The polyethylene and polypropylene matrices provide processability, creating a balanced system with both ease of manufacture and high melt strength.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentUS10472507B2Polymer composition having improved impact strength
Publication Date: 2019.11.12 SABIC GLOBAL TECHNOLOGIES BV

AI summary

The present invention relates to a polymer composition comprising: a) ≥40.0 and <95.0% by weight of one or more propylene-based polymer; b) ≥5.0 and <65.0% by weight of one or more ethylene-based polymer; and c) ≥0.1 and <10.0% by weight of one or more compatibiliser composition; with regard to the total weight of the polymer composition, wherein the propylene-based polymer a) is selected from a propylene homopolymer, a propylene random copolymer, and/or a heterophasic propylene copolymer; the ethylene-based polymer b) is selected from a low-density polyethylene, a linear low-density polyethylene, and/or a high-density polyethylene; and the compatibiliser composition c) comprises one or more polystyrene-poly(ethylene-propylene) block copolymer. Such polymer compositions have good impact strength, high melt strength, good optical properties such as transparency and gloss, and are sufficiently chemically inert. They may be used for the production of transparent containers for storing potable liquids.