Polycarbonate Composition for Thin Wall Mobile Phone Housing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current polycarbonate compositions for mobile phone applications lack optimal balance between high flow and impact resistance, particularly for thin wall products, and often require higher injection molding temperatures that can cause ink washout in IMD processes.
Innovation Solution
A polycarbonate composition combining polycarbonate homopolymers with poly(carbonate-siloxane) copolymers, elastomer-modified graft copolymers, and silicone oil, which provides a melt mass flow rate greater than 16 g/10 min and an Izod notched impact energy of at least 700 J/m, while being processable at lower temperatures to prevent ink washout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high impact strength polycarbonates are used, then impact resistance is improved, but processing temperature increases which causes ink washout in IMD processes
Solution Approach 1:
The patent uses a composite material system consisting of polycarbonate homopolymer blended with poly(carbonate-siloxane) copolymer. This combination allows the material to achieve high impact resistance (Izod notched impact energy ≥ 700 J/m) while maintaining lower processing temperatures suitable for IMD processes, thereby preventing ink washout.
Solution Approach 2:
The patent modifies the material parameters by controlling the siloxane unit content (2.5-10 wt%) and block length (5-120) in the poly(carbonate-siloxane) copolymer. These parameter changes enable the material to achieve optimal balance between impact resistance and processability at lower temperatures.
2Productivity
If high flow polycarbonates are used, then flow properties are improved, but impact strength becomes insufficient for thin wall products
Solution Approach 1:
The patent creates a composite material system where polycarbonate homopolymer is blended with poly(carbonate-siloxane) copolymer. This composite achieves both high flow properties (Melt Mass Flow Rate > 16 g/10 min) and sufficient impact strength (Izod notched impact energy ≥ 700 J/m), making it suitable for thin wall products.
Solution Approach 2:
The patent optimizes the composition parameters by controlling the ratio of polycarbonate homopolymer to poly(carbonate-siloxane) copolymer, and adjusting the siloxane unit content (2.5-10 wt%) and block length (5-120). These parameter changes enable simultaneous achievement of high flow and adequate impact strength.
3Length of stationary object
If part thickness is reduced to meet design trends, then aesthetics and thinness are improved, but flow and impact requirements become more stringent
Solution Approach 1:
The patent develops a composite material system specifically optimized for thin wall applications. The blend of polycarbonate homopolymer and poly(carbonate-siloxane) copolymer with controlled siloxane content provides the necessary flow capability for thin parts (as thin as 0.5 mm) while maintaining adequate impact resistance.
Data Source
AI summary
A polycarbonate composition contains, based on the total weight of the polycarbonate composition: one or more polycarbonate homopolymers; a poly(carbonate-siloxane) copolymer comprising siloxane units with an average block length of 5 to 120, preferably 10 to 100, the poly(carbonate-siloxane) copolymer being present in an amount effective to provide 2.5 to 10 wt % of siloxane units based on the total weight of the polycarbonate composition; 1 to 8 wt % of an elastomer-modified graft copolymer; 0.01 to 5 wt % of a silicone oil; and 0.1 to 8 wt % of an additive; and wherein the composition has a melt mass flow rate higher than 16 g/10 min, determined in accordance with ASTM D1238 under a load of 1.2 kg at 300° C. with a dwelling time of 300 seconds; and an Izod notched impact energy of at least 700 J/m measured at 23° C. on a sample of 3.2 mm thickness according to ASTM D256-10.