Polycarbonate Flame Retardant Scratch Resistant Composition
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Solution Overview
Problem
There is a need for flame retardant thermoplastic polycarbonate compositions that offer improved scratch resistance and mechanical properties, particularly impact strength and flow characteristics, while maintaining good flame performance and being free from bromine and chlorine-based flame retardants.
Innovation Solution
A thermoplastic composition comprising a polycarbonate homopolymer or copolymer with specific carbonate units, an impact modifier with a rubber modified thermoplastic resin having a grafted elastomeric phase, and a flame retardant, where the impact modifier has a specific particle size distribution and Q value, optionally including a polycarbonate-polysiloxane copolymer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If non-brominated and non-chlorinated flame retardants are used, then environmental compliance is improved, but flame performance deteriorates
Solution Approach 1:
The patent uses a composite impact modifier system comprising both emulsion polymerized ABS and bulk polymerized ABS, creating a multi-phase material that achieves both flame retardancy and impact strength. This composite approach allows the different ABS components to work synergistically, with the emulsion polymerized ABS providing flame resistance and the bulk polymerized ABS enhancing mechanical properties.
2Strength
If impact modifiers are added to improve toughness, then impact strength is improved, but scratch resistance deteriorates
Solution Approach 1:
The patent optimizes the particle size distribution of the impact modifiers, specifying that the emulsion polymerized ABS has a mean particle size of 0.1 to 1.0 micrometers and the bulk polymerized ABS has a mean particle size of 1.0 to 5.0 micrometers. This precise parameter control allows the impact modifiers to improve toughness while minimizing their negative effect on scratch resistance by ensuring proper dispersion and interaction with the polycarbonate matrix.
3Productivity
If impact modified blends are used to fill long flow lengths, then flow characteristics are improved, but scratch resistance deteriorates
Solution Approach 1:
The patent creates local quality differences by using two distinct ABS components with different particle sizes and properties. The emulsion polymerized ABS with smaller particles (0.1-1.0 micrometers) provides flow enhancement and fills long flow lengths effectively, while the bulk polymerized ABS with larger particles (1.0-5.0 micrometers) provides structural support and maintains scratch resistance. Each component performs its specific function locally within the composite material.
Data Source
AI summary
A flame retardant thermoplastic composition comprising in combination a polycarbonate homopolymer or copolymer comprising repeat carbonate units having the following structure:wherein R1 and R2 are independently at each occurrence a C1-C4 alkyl, n and p are each an integer having a value of 1 to 4, and T is selected from the group consisting of C5-C10 cycloalkanes attached to the aryl groups at one or two carbons, C1-C5 alkyl groups, C6-C13 aryl groups, and C7-C12 aryl alkyl groups; an impact modifier, wherein the impact modifier comprises wherein the impact modifier comprises a rubber modified thermoplastic resin comprising a discontinuous elastomeric phase dispersed in a rigid thermoplastic phase, and wherein the impact modifier has a specific mean particle size and Q value; and a flame retardant. The compositions have excellent scratch resistance as well as an improved balance of physical properties such as impact strength and spiral flow, while at the same time maintaining their good flame performance.