Copolyamide Refrigerant Tube Structure for R-1234yf Barrier Stability
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Solution Overview
Problem
Current materials for vapor compression circuits in motor vehicle air conditioning, particularly those using R-1234yf as a heat transfer fluid, face challenges in achieving a balance between imperviousness, chemical resistance, mechanical strength, flexibility, and heat resistance, especially when mixed with lubricants like PAG or POE oil, and existing solutions do not fully satisfy these requirements.
Innovation Solution
A thermoplastic structure comprising a copolyamide of formula X/10.T/Y, where X represents aliphatic amino acid residues or units from aliphatic diamine and dicarboxylic acid condensation, 10.T from decane diamine and terephthalic acid, and Y from aliphatic diamine and aromatic dicarboxylic acid, with specific molar proportions, is used to create a layer with enhanced barrier, chemical, and thermal stability, along with improved flexibility and mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyamide materials (PA 6, PA 6.6, PA 6.10) are used for transporting R-1234yf refrigerant, then manufacturing and processing are simplified, but chemical resistance and barrier properties deteriorate due to the high reactivity of R-1234yf with traditional polyamides
Solution Approach 1:
The patent changes the chemical structure parameters of polyamide by introducing aromatic units (terephthalic acid, isophthalic acid) and varying chain lengths (PA 6.10, PA 6.12, PA 10.10, PA 12.12) to achieve optimal resistance against R-1234yf while maintaining processability. This parameter optimization resolves the contradiction between chemical resistance and ease of manufacture.
Solution Approach 2:
The patent employs composite polyamide formulations combining different polyamide types (PA 6.10/PA 6.12 blends, PA 10.10/PA 12.12 blends) to achieve synergistic effects that simultaneously improve chemical resistance to R-1234yf and maintain manufacturing feasibility.
2Strength
If multilayer tubes with rubber-type elastomer and reinforcing braid are used, then mechanical strength and flexibility are improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent applies local quality enhancement by incorporating reinforcing fills (glass fibers, carbon fibers, aramid fibers) at specific locations within the polyamide structure, providing targeted mechanical strength reinforcement without requiring complex multilayer constructions with rubber and braids.
Solution Approach 2:
The patent creates composite polyamide materials by integrating reinforcing fills directly into the polyamide matrix, achieving the mechanical strength of multilayer constructions through a simplified single-material solution that reduces structural complexity.
3Weight of moving object
If thermoplastic materials are used instead of rigid metallic portions, then weight is reduced and flexibility is improved, but heat resistance and mechanical strength at high temperature may deteriorate
Solution Approach 1:
The patent changes the thermal parameters of polyamide by selecting specific polyamide types with higher melting points (PA 6.12, PA 10.10, PA 12.12) and optimizing aromatic content to achieve heat resistance comparable to metals while maintaining the weight and flexibility advantages of thermoplastics.
Solution Approach 2:
The patent enhances heat resistance of thermoplastic polyamide through composite formulations incorporating heat-stabilizing fills and optimizing the polyamide blend composition to maintain dimensional stability and mechanical strength at elevated temperatures near the engine.
4Reliability
If semi-aromatic copolyamide with specific composition is used, then barrier properties and chemical resistance are improved, but manufacturing precision and formulation complexity increase
Solution Approach 1:
The patent establishes specific parameter ranges for semi-aromatic copolyamide formulation (aromatic unit content: 5-50 mol%, chain length ratios, monomer proportions) that define optimal zones for barrier properties while guiding manufacturing toward these precise formulations through clear specification of compositional parameters.
Data Source
AI summary
The invention relates to a thermoplastic structure comprising at least one layer consisting of a composition comprising a copolyamide of formula X/10.T/Y, wherein: X represents either the residues of an aliphatic amino acid comprising between 8 and 18 carbon atoms, or a lactam, or the unit X1.X2 representing the residues resulting from the condensation of an aliphatic diamine comprising between 6 and 18 carbon atoms and a (cyclo)aliphatic diacid comprising between 6 and 18 carbon atoms; 10.T represents the residues resulting from the condensation of a decanediamine and terephthalic acid; and Y represents the residues resulting from the condensation of an aliphatic diamine comprising between 9 and 14 carbon atoms and an aromatic diacid, Y being different from the unit 10.T; the molar proportion of 10.T units in the copolyamide being higher than 0%; the molar proportion of Y units in relation to the group of 10.T and Y units being between 0 and 30%; and the proportion of X units being between 0.4 and 0.8 mole for a mole of semi-aromatic units 10.T and Y.