Polyamide Resin Composition for Gas Barrier and Heat Aging
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Solution Overview
Problem
Polyamides containing an m-xylene group in the polymer principal chain exhibit low heat stability and heat aging resistance, limiting their application in severe use environments, such as high-temperature conditions, despite their excellent gas barrier properties, which is a challenge in fields like automobile parts where both properties are required.
Innovation Solution
A polyamide resin composition comprising a polyamide with a 1,3-bis(aminomethyl)cyclohexane unit, an aromatic secondary amine-based compound, an organic sulfur-based compound, and a phenol-based antioxidant, with specific mass ratios and oxygen permeability coefficients, enhancing both gas barrier and heat aging resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyamides containing an m-xylene group in a polymer principal chain are used, then gas barrier properties are improved, but heat aging resistance deteriorates
Solution Approach 1:
A copper compound is introduced as an intermediary substance that forms a complex with the polyamide containing m-xylene groups. This copper compound complex acts as a mediator that prevents radical formation at the benzyl methyl position, thereby improving heat aging resistance while preserving the excellent gas barrier properties of the original polyamide structure.
Solution Approach 2:
The invention creates a composite material system consisting of polyamide containing m-xylene groups combined with copper compounds and halides. This composite approach allows the synergistic combination of the high gas barrier properties of the polyamide with the heat stabilization effects of the copper compound, resolving the contradiction between these two properties.
2Ease of manufacture
If polyamides containing an m-xylene group are used for injection molding, then moldability is improved, but heat stability deteriorates
Solution Approach 1:
The copper compound serves as an intermediary stabilizer that is incorporated during injection molding processing. It prevents thermal degradation and radical formation during both processing and subsequent heat aging, maintaining heat stability without interfering with the moldability advantages of the polyamide containing m-xylene groups.
Solution Approach 2:
The copper compound and halide are pre-mixed with the polyamide resin before injection molding. This preliminary incorporation ensures that the heat stabilization mechanism is already in place during molding processing, preventing gelation and degradation while maintaining excellent moldability and surface quality.
Data Source
AI summary
Disclosed is a polyamide resin composition having excellent gas barrier properties and heat aging resistance, which contains (A) a polyamide composed of a diamine unit containing a 1,3-bis(aminomethyl)cyclohexane unit and a dicarboxylic unit and at least either of (B) an aromatic secondary amine based compound and (D) a phenol based antioxidant and has an oxygen permeability coefficient of not more than 1.5 cc·mm/m2·day·atm at 23°C and 75 % RH.