Polycarbonate Diol Viscosity Stability
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Solution Overview
Problem
Polycarbonate diols used in production equipment face challenges in balancing mold processability and viscosity stability, particularly at 25°C, and existing formulations like those using 1,6-hexanediol and 3-methyl-1,5-pentanediol with tetrabutyl titanate as a catalyst still require improvement in this regard.
Innovation Solution
A polycarbonate diol with a specific molecular structure, comprising repeating units (A), (B), and (C), and containing terminal hydroxyl groups, with a molecular weight of 300 to 2800 g/mol, and a viscosity ratio η1000/η1 of 0.40 to 0.80 at 25°C, which includes a polycarbonate diol (D) represented by formula (D), is developed to enhance handleability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a polycarbonate diol is used in production equipment involving fluidity, then mold processability is improved, but viscosity stability deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters of the polycarbonate diol by specifying particular repeating units (formulae A, B, C) and molecular weight ranges (300-2800 g/mol). This structural parameter optimization enables the material to achieve both good mold processability and viscosity stability at 25°C, resolving the contradiction between ease of operation and composition stability.
Solution Approach 2:
The patent creates a composite molecular structure containing multiple types of repeating units (A, B, and C) with specific ratios. This composite approach allows the polycarbonate diol to combine the benefits of different structural components, achieving both fluidity for mold processability and molecular uniformity for viscosity stability.
2Ease of operation
If a polycarbonate diol is made liquid at ordinary temperature, then handleability is improved, but molecular weight distribution becomes difficult to control
Solution Approach 1:
The patent specifies precise parameter ranges including molecular weight (300-2800 g/mol), repeating unit composition (90-100 mol% of type A), and structural formulas. These controlled parameters ensure the polycarbonate diol remains liquid at ordinary temperature while maintaining narrow molecular weight distribution and consistent properties.
Data Source
AI summary
A polycarbonate diol having a repeating unit (A) of a carbonate structure, and containing terminal hydroxyl groups, wherein90 to 100 mol % of the repeating unit (A) is a repeating unit (B) of a 3-methylpentan-1,5-diyl group-containing carbonate structure and/or a repeating unit (C) of a 1,6-hexanediyl group-containing carbonate structure,the polycarbonate diol contains a polycarbonate diol (D) represented by the following formula (D),a number average molecular weight calculated from a hydroxyl value of the polycarbonate diol is 300 to 2800 g/mol, andin an LC spectrum measured for the polycarbonate diol, when X0 represents the number of repeating units of the polycarbonate diol (D) corresponding to a peak of molecular weight closest to the above number average molecular weight, the number of consecutive peaks at each of which a peak area value ratio to an area value of the peak at which the number of repeating units is X0 is 0.90 to 1.10 is 2 to 7, including the peak at which the number of repeating units is X0,wherein R1 represents —(CH2)6— or —CH2CH2CH(CH3)CH2CH2—.