Aromatic Polycarbonate Large Volume Bottles Melt Strength
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Solution Overview
Problem
Large volume bottles require high melt strength, which is typically achieved through branching agents or high Fries branching, but these methods compromise optical and impact properties.
Innovation Solution
Aromatic polycarbonate with specific molecular weight, polydispersity, and Fries branching levels, produced by transesterification of bisphenol and diaryl carbonate, is used for injection or extrusion blow molding to create large bottles with improved properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If branched polycarbonate is used to achieve high melt strength for large volume bottles, then the bottle can be successfully manufactured by injection blow molding, but the optical and impact properties are compromised
Solution Approach 1:
The invention changes the molecular weight parameters of the polycarbonate to resolve the contradiction. Specifically, it uses polycarbonate with weight average molecular weight Mw of 25,000-35,000 g/mol and viscosity average molecular weight Mn of 10,000-15,000 g/mol. This parameter optimization provides sufficient melt strength for blow molding while maintaining good optical and impact properties, eliminating the need for branching agents that would compromise material quality.
2Strength
If high Fries branching is introduced to increase melt strength for blow molding, then large volume containers can be produced, but the optical properties deteriorate
Solution Approach 1:
The invention optimizes the molecular weight parameters (Mw: 25,000-35,000 g/mol, Mn: 10,000-15,000 g/mol) to achieve the desired melt strength without relying on high Fries branching. This parameter control allows production of large volume bottles with volume ≥15 liter while maintaining excellent optical clarity and avoiding the degradation caused by excessive Fries branching.
3Strength
If chain branching agents are used in the interfacial process to create branched polycarbonate, then melt strength increases for blow molding suitability, but the manufacturing complexity and cost increase
Solution Approach 1:
The invention extracts and eliminates the need for chain branching agents from the manufacturing process. By optimizing the molecular weight parameters of linear polycarbonate (Mw: 25,000-35,000 g/mol, Mn: 10,000-15,000 g/mol), the process achieves sufficient melt strength for blow molding without requiring additional branching agents, thereby simplifying the manufacturing process and reducing costs.
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 approach allows for the production of high-quality, large volume bottles with balanced optical and impact properties while reducing energy consumption and maintaining quality, as demonstrated by successful bottle production and drop tests.
Implementation Method 1
an aromatic polycarbonate prepared by the transesterification of a bisphenol and a diaryl carbonate
Data Source
AI summary
The present invention relates to the use of an aromatic polycarbonate prepared by the transesterification of a bisphenol and a diaryl carbonate and having a viscosity average molecular weight, Mv, of from 22000 to 32000 g/mol, a polydispersity, defined as Mw/Mn, of from 1.8-3.2, a melt-flow index of from 3.0-10 g/10 min as determined in accordance with ASTM D 1238 (1.2 kg, 300° C.), an amount of Fries branching of from 750 to 2500 ppm, for the manufacture of bottles having a volume of at least 15 liter by means of an injection blow moulding or an extrusion blow moulding process.