Amorphous Aliphatic Polyamides with High Tg and UV Stability
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Solution Overview
Problem
There is a need for a polyamide with high glass transition temperature (Tg) that also exhibits good optical clarity and UV stability, and is biobased, as existing polyamides from renewable resources have limited suitability for high heat applications due to low Tg.
Innovation Solution
An amorphous, aliphatic polyamide is developed with recurring units formed from the polycondensation of a reaction mixture containing 1,4-cyclohexane dicarboxylic acid and linear aliphatic dicarboxylic acids like azelaic or sebacic acid, combined with cycloaliphatic diamines, which achieves a Tg of 160° C to 260° C and high biobased content, while being free of tertiary amines, lactams, and aromatic monomers to ensure transparency and UV resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If polyamides are developed from renewable resources (biobased), then environmental sustainability is improved, but glass transition temperature decreases limiting high heat application suitability
Solution Approach 1:
The patent creates a composite polyamide system combining biobased linear aliphatic dicarboxylic acids (azelaic acid, sebacic acid) with cycloaliphatic diamines and 1,4-cyclohexane dicarboxylic acid. This composite monomer system produces a polyamide that achieves both biobased content (20-80 wt%) and high Tg (160-260°C), resolving the contradiction between environmental sustainability and thermal performance
Solution Approach 2:
The patent systematically varies the molar ratios and types of monomers (azelaic acid, sebacic acid, 1,4-CHDA, cycloaliphatic diamines) to optimize the glass transition temperature while maintaining biobased content. By adjusting these compositional parameters, the polyamide achieves Tg in the range of 160-260°C, overcoming the typical low Tg limitation of biobased polyamides
2Temperature
If aromatic monomers are used to achieve high Tg, then glass transition temperature is improved, but optical clarity and UV stability deteriorate
Solution Approach 1:
The patent replaces aromatic monomers (typically used for high Tg) with cycloaliphatic diamines and linear aliphatic dicarboxylic acids. This substitution uses alternative chemical structures (cycloaliphatic rings with rigid backbones) that provide high Tg (160-260°C) without the harmful UV absorption and yellowing characteristics of aromatic rings, thus maintaining both thermal performance and optical clarity
Solution Approach 2:
The patent introduces specific structural features at local molecular levels - cycloaliphatic rings (isophorone, 1,3-BAC, BAMN structures) that provide localized rigidity and high Tg while maintaining overall molecular flexibility and amorphous structure. This local structural optimization achieves high Tg without compromising optical clarity and UV stability
3Temperature
If tertiary amines, lactams, or aromatic monomers are included to achieve high Tg, then glass transition temperature is improved, but transparency and UV resistance deteriorate
Solution Approach 1:
The patent explicitly excludes tertiary amines, lactams, and aromatic monomers from the reaction mixture. By removing these components that would compromise transparency and UV resistance, the patent relies solely on cycloaliphatic diamines and linear aliphatic dicarboxylic acids to achieve the required Tg through their rigid molecular structures, thus eliminating the trade-off between Tg and optical properties
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting polyamide has excellent optical clarity, improved UV stability, and high Tg, making it suitable for applications involving elevated temperatures, with a biobased content that promotes elevated Tg and resistance to moisture absorption, suitable for applications such as cookware and medical devices.
Implementation Method 1
recurring units formed from the polycondensation of a reaction mixture including: a dicarboxylic acid component (DC) and a diamine component (DA)
Data Source
AI summary
Described herein are amorphous and transparent aliphatic polyamides (PA) formed from the polycondensation of monomers in a reaction mixture (RM) including a dicarboxylic acid component (DC) and a diamine component (DA). The dicarboxylic acid component (DC) includes 25 mol % to 80 mol % of 1,4-cyclohexane dicarboxylic acid (“1,4-CHDA”) and 20 mol % to 75 mol % of a linear, aliphatic dicarboxylic acid selected from azelaic acid, sebacic acid or a combination thereof. The diamine component (DA) includes a cycloaliphatic diamine selected from the group consisting of isophoronediamine (“IPDA”); 4,4′-methyl-enebis(2-methylcyclohexylamine) (“MACM”); 4,4′-methylene-bis-cyclohexane (“PACM”); 1,3-bis(aminomethyl)cyclohexane (“1,3-BAC”), bis(aminomethyl)norborane (“BAMN”) and any combination of two or more thereof. It was surprisingly found that the polyamides (PA), while being bio-based (at least in part due to the linear aliphatic dicarboxylic acid), had excellent optical clarity, improved UV stability and desirably high Tg.