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 between high rigidity, high notched impact strength, and cost-effectiveness, while also meeting stringent flame retardancy requirements, particularly for thin wall thicknesses.
Innovation Solution
A flame-retardant molding compound comprising 45.5-95 parts by weight of aromatic polycarbonate or polyester carbonate, 1.0-15.0 parts by weight of rubber-modified graft polymer, 1.0-9.5 parts by weight of cyclic phosphazene, 0-15.0 parts by weight of rubber-free vinyl (co)polymer or polyalkylene terephthalates, 1.0-25.0 parts by weight of talc, and 0-5.0 parts by weight of additives, optimized to achieve low phosphazene content and excellent mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high phosphazene content is used to achieve UL94 V-0 classification at thin wall thicknesses, then flame retardancy is improved, but production cost increases significantly
Solution Approach 1:
The patent changes the chemical structure parameters of the phosphazene flame retardant by specifying exact ratios of different phosphazene components (trimer, tetramer, and higher oligomers in specific proportions). This parameter optimization allows achieving UL94 V-0 classification at 1.5 mm thickness with lower total phosphazene content (1.0-9.5 parts by weight), thereby reducing cost while maintaining flame retardancy
Solution Approach 2:
The patent creates a composite flame retardant system by combining multiple phosphazene oligomers with specific molecular weights in defined proportions, along with rubber-modified graft polymer and talc. This composite approach enhances flame retardancy efficiency, allowing reduced overall flame retardant loading while meeting UL94 V-0 requirements
2Strength
If rubber-modified graft polymer is added to improve notched impact strength, then mechanical toughness is improved, but rigidity (modulus of elasticity) deteriorates
Solution Approach 1:
The patent optimizes the quantity parameter of rubber-modified graft polymer to a specific range (1.0-15.0 parts by weight, preferably 3.0-12.5 parts) and controls the talc filler content (1.0-25.0 parts by weight, preferably 3.0-9.0 parts) to balance the rigidity-toughness trade-off. This quantitative control allows achieving both high notched impact strength and adequate rigidity
Solution Approach 2:
The patent develops a multi-phase composite material system combining polycarbonate matrix, rubber-modified graft polymer (providing toughness), and talc filler (providing rigidity reinforcement). The synergistic interaction between these components allows simultaneous improvement of both impact strength and rigidity, resolving the traditional trade-off
3Reliability
If cyclic phosphazene with high trimer content is used to achieve good flame retardancy and mechanical properties, then flame retardancy is improved, but the specification and control complexity increases
Solution Approach 1:
The patent specifies precise compositional parameters for the cyclic phosphazene: trimer content (k=1) of 60-98 mol% (preferably 65-95 mol%), with corresponding tetramer (k=2) and higher oligomer ranges. These quantified specifications provide clear control criteria for manufacturing while achieving optimal flame retardancy and mechanical properties
Data Source
AI summary
The invention relates to flame-retardant, impact-modified polycarbonate (PC) compositions and moulding materials which display good mechanical properties, good chemical resistance and high hydrolysis stability, and contain: A) 95.0 parts by weight of aromatic polycarbonate and/or aromatic polyester carbonate; B) 1.0 - 15.0 parts by weight of rubber-modified graft polymerisates; C) 1.0 - 9.5 parts by weight of at least one cyclic phosphazene according to formula (X), in which k stands for 1 or a whole number from 1 to 10, preferably a number from 1 to 8 and particularly from 1 to 5, in which the proportion of trimers (k=1) lies between 60 and 98 mol.-% in relation to component C, and where R is the same or different in each case and stands for an amine group, C1- to C8-alkyl that, if required, is halogenated, preferably halogenated with fluorine and is preferably methyl, ethyl, propyl or butyl, C1-to C8 alkoxy, preferably methoxy, ethoxy, propoxy or butoxy, C5-to C6-cycloalkyl which, if required, is substituted with alkyl, preferably C1-C4-alkyl and/or halogen, preferably chlorine and/or bromine, C6-to C20-aryloxy which, if required, is substituted with alkyl, preferably C1-C4-alkyl, and/or halogen, preferably chlorine, bromine and/or hydroxy, and is preferably phenoxy, naphthyloxy, C7-to C12-aralkyl which, if required, is substituted with alkyl, preferably C1-C4-alkyl and/or halogen, preferably chlorine and/or bromine, and is preferably phenyl-Ci-C/i-alkyl, or a halogen group, preferably chlorine, or an OH group; D) 0 - 15.0 parts by weight of rubber-free vinyl(co)polymerisate polyalkylene terephthalate; E) 1.0 - 25.0 parts by weight of talc with an average particle size dso between 0.1 and 4.0 μm; F) 0 - 5.0 parts by weight of additives; and G) 0.05 to 5.0 parts by weight of an anti-dripping agent; in which all the weight part indications are standardised such that the sum of the weight parts of all the components A+B+C+D+E+F+G in the composition equals 100. The application also relates to the use of the compositions for producing moulded elements, as well as to the moulded elements produced from said compositions.