Transparent Polyolefin Composition for Impact Resistance and Low Haze
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polypropylene blends with elastomeric olefin copolymers typically suffer from opacity due to refractive index differences, making it challenging to achieve a balance of impact resistance, tensile properties, and transparency.
Innovation Solution
A polyolefin composition comprising 70-98% propylene homopolymer or copolymer with a haze of 25% or less and 2-30% butene-1 copolymer, which provides a balance of mechanical and optical properties, including low haze and high tensile strength, achieved through specific polymerization processes and catalyst systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If elastomeric olefin copolymer is added to polypropylene to improve impact resistance and flexibility, then mechanical properties are improved, but transparency deteriorates due to refractive index differences
Solution Approach 1:
The patent changes the chemical composition parameters by introducing butene-1 copolymer with specific comonomer content (0.5-30%) and controlling the propylene homopolymer composition (70-98% propylene). This parameter adjustment optimizes the balance between mechanical properties and optical clarity by selecting specific polymer compositions that maintain compatible refractive indices while providing the desired mechanical enhancement.
Solution Approach 2:
The patent creates a composite polyolefin material combining propylene homopolymer/copolymer with butene-1 copolymer in specific proportions (70-98% propylene component and 2-30% butene-1 copolymer component). This composite structure leverages the complementary properties of each polymer: propylene provides transparency and structural integrity, while butene-1 copolymer contributes flexibility and impact resistance, achieving a synergistic effect that resolves the contradiction between transparency and mechanical strength.
2Strength
If butene-1 copolymer is added to propylene homopolymer to improve mechanical properties, then tensile strength and flexibility are improved, but haze increases
Solution Approach 1:
The patent precisely controls the composition parameters by limiting butene-1 copolymer content to 2-30% and specifying comonomer content of 0.5-30% in the butene-1 copolymer. It also controls propylene homopolymer composition at 70-98% with specific melting temperature requirements (130°C or higher). These parameter optimizations ensure that the mechanical property enhancement from butene-1 copolymer does not exceed the transparency threshold, maintaining haze at acceptable levels while achieving desired tensile strength.
3Temperature
If propylene homopolymer with high melting temperature is used to improve heat resistance, then thermal stability is improved, but processing difficulty increases
Solution Approach 1:
The patent specifies a melting temperature range of 130-165°C for the propylene homopolymer/copolymer component, which represents an optimization balance. This temperature range provides sufficient thermal stability for application performance while remaining within the practical processing window for injection molding and other manufacturing processes. The specification of 130°C or higher melting temperature ensures heat resistance while the upper limit implied by the composition ranges maintains processability.
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 composition achieves excellent transparency and mechanical properties, such as high flexural modulus and impact resistance, while maintaining low haze values, suitable for injection molded articles.
Implementation Method 1
blending propylene polymers with butene copolymers
Implementation Method 2
shows an unusual balance of impact resistance, tensile properties and transparency (low haze)
Data Source
AI summary
A polyolefin composition having good transparency and mechanical properties comprising, all percent amounts being by weight: A) from 70 to 98% of a propylene homopolymer or copolymer having haze of 25% or less and melting temperature of 130° C. or higher; and B) from 2 to 30% of a butene-1 copolymer containing from 0.5 to 30% of one or more comonomer(s).