Branched Polypropylene Copolymer for ISBM Melt Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polypropylene (PP) lacks the necessary melt strength for effective injection stretch blow molding (ISBM) and has low impact resistance, particularly at low temperatures, limiting its applications compared to polyethylene terephthalate (PET) and high-density polyethylene (HDPE).
Innovation Solution
A composition comprising a polypropylene copolymer with a branched structure derived from propylene and alpha-olefins, such as ethylene, with a melt flow index between 5-30 g/10 minutes, and a crystallization temperature below 130°C, which is processed with poly(sulfonyl azide) or other branching agents to enhance melt strength and optical clarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polypropylene is used for injection stretch blow molding, then cost is reduced and chemical resistance is improved, but melt strength is insufficient
Solution Approach 1:
The patent modifies the molecular architecture of polypropylene by introducing long chain branches through reaction with poly(sulfonyl azide), changing parameters such as melt strength, viscosity, and branching index to achieve suitable ISBM processability while maintaining chemical resistance and cost benefits
Solution Approach 2:
The patent creates a composite molecular structure within polypropylene by incorporating grafted poly(sulfonyl azide) chains, forming a composite material system that combines the inherent advantages of PP with the reinforcing effect of the grafted branches to achieve both high melt strength and processability
2Strength
If propylene homopolymer is used, then stiffness and heat resistance are improved, but impact resistance deteriorates
Solution Approach 1:
The patent changes the molecular structure parameters of polypropylene by introducing long chain branches through poly(sulfonyl azide) grafting, which modifies the material's toughness and impact resistance while maintaining the stiffness and heat resistance characteristics of the polypropylene base polymer
3Ease of manufacture
If polyethylene terephthalate or high density polyethylene is used for ISBM, then melt strength is sufficient, but cost increases and chemical resistance decreases
Solution Approach 1:
The patent transforms polypropylene into an ISBM-suitable material by changing its rheological parameters through controlled branching, enabling it to achieve melt strength comparable to PET and HDPE while retaining the cost and chemical resistance advantages of polypropylene
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 resulting polypropylene composition achieves high melt strength suitable for ISBM, maintaining excellent optical clarity and providing a balance of mechanical, chemical, and thermal resistance, enabling successful ISBM processing with improved material distribution and reduced haze in molded articles.
Implementation Method 1
The composition is made by mixing, for example, extruding, the random copolymer of propylene and at least one comonomer with a poly(sulfonyl azide) at an elevated temperature
Implementation Method 2
The composition is made by branching or crosslinking the random copolymer of propylene using a peroxide, an acrylate, a siloxane, a second polymer having vinyl functional groups, or e-beam
Implementation Method 3
The composition is made by branching or crosslinking the random copolymer of propylene using a peroxide, an acrylate, a siloxane, a second polymer having vinyl functional groups, or e-beam
Implementation Method 4
The composition has a crystallization temperature of less than 130° C. (e.g., 100-130° C.)
Implementation Method 5
a melting temperature in a range of from about 140° C. to 180° C.
Data Source
AI summary
A composition comprising polypropylene having a high melt strength suitable for an injection stretch blow molding (ISBM) process is provided. Such a composition includes a polypropylene (PP) copolymer having a branched structure. The PP copolymer is a random copolymer derived from propylene and at least one comonomer selected from ethylene, any C4-C8 alpha-olefin, or any combinations thereof. The composition has a melt flow index in a range of from 8 g/10 minutes to 30 g/10 minutes. A resulting fabricated article, a method of making the composition, and a method of using the composition are also provided.