Polycarbonate Core-Shell Rubber Flame Retardant Composition
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Solution Overview
Problem
There is a continuous need for a thermoplastic composition that balances good flame retardancy with good impact strength, as existing compositions often compromise on one property when improving the other.
Innovation Solution
A thermoplastic composition comprising a non-branched polycarbonate resin, a silicon-containing rubber with a core/shell structure, and a metal (oxy)hydroxide with a BET surface area of at least 10, which combines to achieve both high flame retardancy and impact strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flame retardant additives are added to improve flame resistance, then flame retardancy is improved, but impact strength deteriorates
Solution Approach 1:
The patent uses a composite material system consisting of polycarbonate resin combined with core-shell rubber particles having a specific structure (cross-linked rubber core with polycarbonate graft shell). This composite structure provides both flame retardancy and maintained impact strength, resolving the contradiction between these two properties.
Solution Approach 2:
The invention applies local quality by creating a core-shell structure where the core and shell have different functions. The core provides elasticity and impact absorption, while the shell provides compatibility with the polycarbonate matrix and flame retardancy. This localized functional differentiation allows simultaneous achievement of flame resistance and impact strength.
2Strength
If impact modifiers are added to improve impact strength, then impact strength is improved, but flame retardancy deteriorates
Solution Approach 1:
The patent employs a specially designed composite material where core-shell rubber particles are combined with polycarbonate resin. The unique structure of the core-shell particles allows them to function as impact modifiers without significantly compromising flame retardancy, unlike conventional impact modifiers.
Solution Approach 2:
The core-shell structure enables local quality differentiation where the rubber core provides impact modification functionality while the polycarbonate-grafted shell maintains flame retardant properties by being compatible with the flame-retardant polycarbonate matrix.
3Strength
If rubber particles are added to improve impact strength, then impact strength is improved, but hydrolytic stability deteriorates
Solution Approach 1:
The invention applies local quality by coating the rubber core with a polycarbonate-grafted shell. This shell acts as a protective barrier that prevents hydrolytic degradation of the rubber core while maintaining the impact modification functionality. The shell's chemical structure provides both mechanical protection and chemical stability.
Solution Approach 2:
The polycarbonate-grafted shell acts as an intermediary layer between the rubber core and the external environment. It protects the rubber core from hydrolytic attack while maintaining compatibility with the polycarbonate matrix, thus preserving both impact strength and hydrolytic stability.
Data Source
AI summary
The present invention relates to a thermoplastic composition comprising: a) a1) a thermoplastic resin and a2) a silicon containing rubber and/or b) a polysiloxane-polycarbonate copolymer; and c) a metal (oxy)hydroxide with BET surface area of at least 10 as determined by DIN ISO 9277: 2010.