Low Gloss Thermoplastic Composition via Segmented Impact Modifiers
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Solution Overview
Problem
Existing thermoplastic compositions with aromatic polycarbonate struggle to achieve a low gloss and good impact resistance at low temperatures while maintaining processability.
Innovation Solution
A thermoplastic composition comprising 10-90% aromatic (co)poly(ester)carbonate, 10-90% first graft polymer with a grafted phase, 1-20% linear glycidyl ester functional polymer, and 1-20% second graft polymer with a core-shell structure of poly alkyl(meth)acrylate and polyorganosiloxane, which provides a low 60° gloss and improved impact strength at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aromatic polycarbonate composition contains rubber modified copolymer with high polybutadiene content and large particle size, then impact resistance is improved, but gloss level increases (low gloss cannot be achieved)
Solution Approach 1:
The invention divides the impact modifier system into two distinct components: (1) a first graft copolymer with moderate polybutadiene content (5-20%) and controlled particle size (0.5-5.0 microns) that provides baseline impact resistance, and (2) a second graft copolymer with high polybutadiene content (80-95%) and small particle size (0.05-2.0 microns) that enhances low-temperature impact resistance without significantly affecting gloss. This segmentation allows each component to perform its specific function optimally.
Solution Approach 2:
The invention applies different characteristics to different components of the impact modifier system. The first graft copolymer has moderate rubber content and larger particles for general impact resistance, while the second graft copolymer has high rubber content and small particles specifically for low-temperature performance. The small particle size of the second copolymer ensures it does not significantly increase surface gloss, thus maintaining the low gloss appearance.
Solution Approach 3:
The invention uses a composite approach by combining two different graft copolymers with distinct compositions and particle size distributions. The first graft copolymer contains 5-20% polybutadiene with 0.5-5.0 micron particles, while the second contains 80-95% polybutadiene with 0.05-2.0 micron particles. This composite system achieves synergistic effects, providing both room temperature and low temperature impact resistance while maintaining low gloss surface finish.
2Illumination intensity
If aromatic polycarbonate composition uses impact modifying graft with particle size less than 0.75 micron, then low gloss is achieved, but impact resistance at low temperatures deteriorates
Solution Approach 1:
The invention segments the impact modification function between two copolymers: the first graft copolymer (with 0.5-5.0 micron particles) maintains low gloss and provides baseline impact resistance, while the second graft copolymer (with 0.05-2.0 micron particles and 80-95% polybutadiene) specifically targets low-temperature impact resistance. The high polybutadiene content in the second copolymer provides the necessary flexibility and energy absorption at low temperatures.
Solution Approach 2:
The invention changes key parameters of the second graft copolymer compared to conventional single-phase impact modifiers: (1) polybutadiene content is increased to 80-95% (vs. typical 1-18%), (2) particle size is optimized to 0.05-2.0 microns (smaller than conventional but not as small as the first copolymer), and (3) it is used in a specific quantity range (1-20 parts by weight per 100 parts polycarbonate). These parameter changes enable improved low-temperature impact resistance while maintaining acceptable gloss levels.
3Reliability
If aromatic polycarbonate composition contains multiple specialized components for low gloss and impact resistance, then performance is improved, but processability may be affected
Solution Approach 1:
The invention optimizes the particle size parameters of both graft copolymers to ensure good processability. The first graft copolymer has particle size of 0.5-5.0 microns and the second has 0.05-2.0 microns, both ranges that facilitate uniform dispersion and melting during injection molding. The quantity ratios are also carefully controlled (first copolymer: 5-50 parts, second copolymer: 1-20 parts per 100 parts polycarbonate) to maintain melt flow properties.
Solution Approach 2:
The invention uses a composite of two graft copolymers with complementary properties that together provide synergistic performance while maintaining processability. The first copolymer provides structural stability and low gloss, while the second copolymer enhances impact resistance. Their combined presence in specific ratios ensures that the composition remains processable through conventional injection molding techniques while achieving superior performance.
Data Source
AI summary
A thermoplastic composition suitable for making articles having low gloss and good impact resistance at low temperatures is disclosed. The composition contains (A) 10 to 90 percent relative to the weight of the composition (pbw) of an aromatic (co)poly(ester)carbonate, (B) 10 to 90 pbw of first graft (co)polymer containing a graft base selected from the group consisting of polyurethane, ethylene vinyl acetate, silicone, ethylene-propylene diene rubbers, ethylene propylene rubbers, acrylate rubbers, diene rubbers, and polychloroprene, and a grafted phase, (C) 1 to 20 pbw of a linear glycidyl ester functional polymer comprising repeating units derived from one or more glycidyl ester monomers and (D) 1 to 20 pbw of a second graft (co)polymer containing a core and shell wherein the core contains an interpenetrated network of poly(meth)alkyl acrylate and polyorganosiloxane, and wherein the shell contains poly(meth)acrylate.