Flame-Retardant Polycarbonate Molding Compound with Cyclic Phosphazene
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Solution Overview
Problem
Existing flame-retardant polycarbonate compositions face challenges in achieving a balance of high heat resistance, very high notched impact strength, and high hydrolysis stability while maintaining good mechanical properties and reducing phosphazene content to lower production costs.
Innovation Solution
A flame-retardant molding compound comprising 80-98 parts by weight of aromatic polycarbonate or polyester carbonate, 0.5-6 parts by weight of rubber-modified graft polymer, 1-4.5 parts by weight of cyclic phosphazene with specific trimer content, and optional additives, excluding inorganic flame retardants and other organic compounds, to achieve desired properties with low phosphazene content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphazene content is increased to improve flame retardancy, then flame retardancy is improved, but production cost increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oligomer distribution of cyclic phosphazenes, specifically setting the trimer content to 60-98 mol% and the average oligomer number n to 1.10-1.75. This optimization allows achieving UL94 V-0 flame retardancy with reduced phosphazene content (1.0-5.0 parts by weight), thereby lowering production costs while maintaining excellent flame retardancy even with thin wall thicknesses (1.0-1.5 mm).
Solution Approach 2:
The patent employs composite materials by combining cyclic phosphazenes with specific oligomer distribution with rubber-modified graft polymers (0.5-6.0 parts by weight) and aromatic polycarbonate (80-98 parts by weight). This composite formulation achieves synergistic effects where the optimized phosphazene composition enhances flame retardancy while the rubber modification maintains mechanical properties, allowing cost-effective formulation with minimal phosphazene content.
2Strength
If impact strength is improved by adding rubber-modified graft polymer, then notched impact strength is improved, but mechanical properties may be compromised
Solution Approach 1:
The patent applies parameter changes by optimizing the rubber-modified graft polymer content to 0.5-6.0 parts by weight and controlling the graft polymer's gel content (20-80%) and particle size (0.05-2.0 μm). This precise parameter control ensures adequate notched impact strength while preserving other mechanical properties such as tensile strength and rigidity, preventing over-modification that would compromise overall mechanical performance.
3Reliability
If flame retardancy is improved with thin wall thickness, then flame retardancy is improved, but mechanical strength may be reduced
Solution Approach 1:
The patent employs composite materials with a specifically formulated system combining aromatic polycarbonate (80-98 parts by weight), rubber-modified graft polymer (0.5-6.0 parts by weight), and optimized cyclic phosphazene (1.0-4.5 parts by weight with n=1.10-1.75). This composite achieves UL94 V-0 flame retardancy with thin wall thicknesses (1.0-1.5 mm) while maintaining adequate mechanical strength through the synergistic interaction of components, where the rubber modification provides toughness and the optimized phosphazene provides flame protection without excessive weight or strength loss.
Data Source
AI summary
The invention relates to flame-retardant, impact-modified polycarbonate (PC) compositions and molding materials that have good mechanical properties, good chemical resistance, and high hydrolysis stability, containing: A) 80 - 98 parts by weight of aromatic polycarbonate and/or aromatic polyester carbonate, B) 0.5 - 6.0 parts by weight of rubber-modified graft polymer, C) 0.8 - 5.0 parts by weight of at least one cyclic phosphazene according to formula (X), wherein k stands for 1 or an integer number from 1 to 10, preferably for a number from 1 to 8, especially preferably 1 to 5, wherein the trimer portion (k=1) is 60 to 98 mol % with respect to component C and wherein each R is the same or different and stands for an amine residue, C1 to C8 alkyl, preferably methyl, ethyl, propyl, or butyl, which is optionally halogenated, preferably halogenated with fluorine, C1 to C8 alkoxy, preferably methoxy, ethoxy, propoxy, or butoxy, C5 to C6 cycloalkyl, which is optionally substituted with alkyl, preferably with C1 to C4 alkyl, and/or with halogen, preferably with chlorine and/or bromine, C6 to C20 aryloxy, preferably phenoxy or naphthyloxy, which is optionally substituted with alkyl, preferably with C1 to C4 alkyl, and/or with halogen, preferably with chlorine or bromine, and/or with hydroxy, C7 to C12 aralkyl, which is optionally substituted with alkyl, preferably with C1 to C4 alkyl, and/or with halogen, preferably with chlorine and/or bromine, preferably phenyl C1 to C4 alkyl, or a halogen residue, preferably chlorine, or an OH residue, D) 0 - 5.0 parts by weight of rubber-free vinyl (co)polymer or polyalkylene terephthalate, E) 0 - 15.0 parts by weight of additives, F) 0.05 - 1.0 parts by weight of anti-dripping agent, wherein all specifications of parts by weight are normalized in such a way that the sum of the parts by weight of all components A+B+C+D+E+F in the composition is 100. The invention further relates to the use of the compositions to produce molded bodies and the molded bodies produced from the compositions.