Polyester Resin Composition Suppressing Flow Marks
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Solution Overview
Problem
The formation of flow marks in molded articles made from polybutylene terephthalate and polyethylene terephthalate resin compositions, which are exacerbated by rapid changes in injection speed and thickness, leading to poor surface appearance and increased gas emission, is not adequately addressed by conventional techniques.
Innovation Solution
A polyester resin composition comprising 82-88% polybutylene terephthalate, 12-18% polyethylene terephthalate, a metal organic acid salt, and an inorganic filler with specific particle size and content, along with controlled molding conditions, to minimize flow marks and gas emission while maintaining high heat resistance and surface smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polybutylene terephthalate and polyethylene terephthalate are used together to achieve excellent surface smoothness without primer process, then surface smoothness is improved, but flow mark formation increases and heat resistance becomes insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the ratio of polybutylene terephthalate to polyethylene terephthalate within specific ranges (polybutylene terephthalate: 70-90 parts, polyethylene terephthalate: 10-30 parts) to optimize both surface smoothness and flow mark suppression while maintaining heat resistance
Solution Approach 2:
The patent uses composite materials by combining polybutylene terephthalate and polyethylene terephthalate in specific proportions to create a resin composition that achieves synergistic effects - the polybutylene terephthalate provides heat resistance and structural stability while the polyethylene terephthalate enhances surface smoothness, with the composite formulation preventing flow mark formation
2Object-affected harmful factors
If injection speed is decreased rapidly to reduce flow marks, then flow mark formation is reduced, but molding productivity decreases and surface appearance deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting the resin composition ratios and molding conditions (temperature, pressure, time) to achieve optimal balance between flow mark suppression and molding efficiency, allowing faster injection speeds without compromising surface quality
3Temperature
If polybutylene terephthalate is used to achieve high heat resistance, then heat resistance is improved, but surface smoothness deteriorates without primer process
Solution Approach 1:
The patent uses composite materials by combining polybutylene terephthalate (providing heat resistance) with polyethylene terephthalate (providing surface smoothness) in optimized ratios, creating a synergistic composite that achieves both heat resistance and surface smoothness without requiring primer processes
Data Source
AI summary
The polyester resin composition includes: a polyester resin A containing 82 to 88 mass % of a polybutylene terephthalate resin and 12 to 18 mass % of a polyethylene terephthalate resin; a metal organic acid salt B that is either one or both of an alkali metal organic acid salt and an alkaline earth metal organic acid salt; and an inorganic filler C having an average particle diameter of 0.05 to 3 μm in an amount of 1 to 13 parts by mass based on 100 parts by mass of the polyester resin A, wherein the polyester resin composition includes either one or both of alkali metal atoms and alkaline earth metal atoms in an amount of 0.000005 to 0.05 parts by mass based on 100 parts by mass of the polyester resin A, and a content of linear oligomers of polybutylene terephthalate or the like is not more than 1000 mg/kg.