Polycarbonate Diol Composition for Polyurethane Storage Stability
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Solution Overview
Problem
Conventional polycarbonate diols used in polyurethanes face challenges in achieving balanced physical properties such as chemical resistance, contamination resistance, low-temperature flexibility, and storage stability, with crystalline diols causing storage instability and branched diols reducing flexibility.
Innovation Solution
A polycarbonate diol with a specific composition, including structural units derived from 2,2-dimethyl-1,3-propanediol and 1,4-butanediol, with a controlled molecular weight and branching ratio, is developed to enhance chemical resistance, contamination resistance, and low-temperature flexibility while maintaining storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If crystalline polycarbonate diols synthesized from 1,6-hexanediol are used, then chemical resistance and contamination resistance are improved, but storage stability of polyurethane solution deteriorates
Solution Approach 1:
The invention uses a composite diol system combining cyclic carbonate (providing chemical resistance) with chain extender diol (providing storage stability), creating a polyurethane that balances both properties through material composition rather than relying on a single diol type
Solution Approach 2:
The invention changes the molecular weight parameters of the diol components, specifically using cyclic carbonate with 50-200 g/mol and chain extender diol with 100-500 g/mol, along with controlling the diol ratio at 5-50 parts by weight, to achieve both chemical resistance and storage stability
2Stability of the object's composition
If amorphous polycarbonate diols are used by copolymerizing branched aliphatic diol, then storage stability is improved, but chemical resistance and contamination resistance deteriorate
Solution Approach 1:
The invention replaces the conventional composite approach (amorphous polycarbonate diol + crystalline polycarbonate diol) with a new composite system (cyclic carbonate + chain extender diol), where the cyclic carbonate provides chemical resistance and the chain extender diol provides storage stability without compromising either property
3Reliability
If polycarbonate diol with reduced molecular weight and increased small molecular weight diol ratio is used, then solvent resistance and contamination resistance are improved, but crystallinity increases and storage stability deteriorates
Solution Approach 1:
The invention optimizes the molecular weight parameters within specific ranges (cyclic carbonate: 50-200 g/mol, chain extender diol: 100-500 g/mol) and controls the diol ratio (5-50 parts by weight) to achieve solvent resistance without excessive crystallinity, thereby maintaining storage stability
Data Source
AI summary
Provided is a polycarbonate polyol used as a raw material of a polyurethane that yields a polyurethane solution having good storage stability and exhibits excellent flexibility and solvent resistance. This polycarbonate polyol is a polycarbonate diol that includes structural units represented by the following Formulae (A) and (B), wherein, R1 and R2 each independently represent an alkyl group having 1 to 4 carbon atoms and, in this range of the number of carbon atoms, optionally have an oxygen atom, a sulfur atom, a nitrogen atom, a halogen atom, or a substituent containing these atoms; and R3 represents a linear aliphatic hydrocarbon having 3 or 4 carbon atoms. This polycarbonate diol has a molecular weight of 500 to 5,000, and the value of the following Formula (I) is 0.3 to 20.0: (Content ratio of branched-chain moiety in polymer)/(Content ratio of carbonate group in polymer) × 100 (%) (I) .