Polycarbonate Composition Adhesion to Polyurethane via Graft Polymer
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Solution Overview
Problem
Existing polycarbonate compositions fail to achieve good adhesion to polyurethane systems after temperature change tests, while also lacking high low-temperature toughness, heat resistance, high modulus of elasticity, and low overall shrinkage.
Innovation Solution
A polycarbonate composition comprising 30-45 parts of aromatic polycarbonate or polyester carbonate, 32-54 parts of polybutylene terephthalate, and 16-23 parts of a polybutadiene-based graft polymer with a specific vinyl monomer content, combined with a polyurethane layer, where the polybutadiene content is 8-18% and butadiene-free vinyl polymer is 3-12%, and the graft polymer is produced by emulsion polymerization with specific stabilizers and no fillers or flame retardants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polycarbonate compositions are used, then processing ease is maintained, but adhesion to polyurethane systems deteriorates after temperature change tests
Solution Approach 1:
The invention modifies the chemical composition parameters of the polycarbonate system by introducing specific ratios of polybutylene terephthalate (32-54 parts) and polybutadiene-based graft polymer (16-23 parts) to achieve improved adhesion while maintaining processing characteristics
Solution Approach 2:
The invention creates a composite polycarbonate composition combining multiple polymer components (aromatic polycarbonate, polybutylene terephthalate, and polybutadiene-based graft polymer) to achieve synergistic effects that improve adhesion to polyurethane systems while maintaining mechanical properties
2Reliability
If polycarbonate composition is modified to improve adhesion, then bonding strength increases, but low-temperature toughness may deteriorate
Solution Approach 1:
The invention optimizes the molecular weight and composition parameters of the graft polymer and polybutylene terephthalate to ensure that adhesion improvement does not compromise low-temperature toughness, maintaining impact strength above 50 kJ/m² at -30°C
Solution Approach 2:
The invention introduces polar groups at specific locations within the polymer structure (through polybutylene terephthalate and graft polymer configuration) to enhance interfacial adhesion to polyurethane while maintaining bulk mechanical properties through appropriate molecular weight selection
3Reliability
If polymer composition is adjusted for better adhesion, then bonding improves, but heat resistance may worsen
Solution Approach 1:
The invention selects specific molecular weight ranges and composition ratios that balance adhesion enhancement with thermal stability, ensuring Vicat softening point remains above 150°C while achieving improved adhesion
Solution Approach 2:
The invention uses polybutylene terephthalate as an intermediary component that provides both adhesion promotion through polar groups and thermal stability through its crystalline structure, acting as a bridge between the polycarbonate substrate and polyurethane coating
4Reliability
If composition is optimized for adhesion and mechanical properties, then overall performance improves, but shrinkage control becomes difficult
Solution Approach 1:
The invention optimizes the crystallinity and composition parameters of the polymer blend to achieve balanced shrinkage behavior, keeping overall shrinkage within 1.0-1.5% while maintaining improved adhesion and mechanical properties
Data Source
Figure 1
AI summary
The present invention relates to compositions comprising A) 30 to 45 parts by weight of at least one polymer selected from the group consisting of aromatic polycarbonate and aromatic polyester carbonate, B) 32 to 54 parts by weight of at least one polyalkylene terephthalate, preferably a polybutylene terephthalate, C) 16 to 23 parts by weight of at least one mixture comprising at least one polybutadiene-containing vinyl (co)polymer and at least one polybutadiene-free vinyl (co)polymer, D) 0.1 to 20.0 parts by weight (based in each case on the sum total of components A to C) of at least one polymer additive, where the polybutadiene content based on the sum total of the parts by weight of components A to C is 8% to 18% by weight, and where the total content of butadiene-free vinyl (co)polymer from component C based on the sum total of the parts by weight of components A to C is 3% to 12% by weight, and where the sum total of the parts by weight of components A to C in the polycarbonate composition is normalized to 100, and to composite components formed from these compositions and a polyurethane layer, which are notable for improved adhesion between the two layers, and to a process for producing the composite components.