Polyurethane Lens Production via Acidic Phosphate Ester Modification
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Solution Overview
Problem
The existing methods for producing polyurethane lenses using polyisocyanate and polythiol compounds face issues with high reactivity leading to increased viscosity over time and degradation due to water exposure, affecting workability.
Innovation Solution
A method involving the mixing of a polyisocyanate compound with a specific acidic phosphate ester and a polythiol compound obtained through esterification of a polyol compound and thioglycolic acid, along with a polymerization catalyst, to form a composition that minimizes viscosity increase and prevents water-induced degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a polyisocyanate compound and a polythiol compound (obtained through esterification of polyol and thioglycolic acid) are mixed, then high reactivity is achieved, but viscosity increases notably with time, causing deterioration in workability
Solution Approach 1:
The patent applies preliminary action by pre-mixing the polyisocyanate compound with the acidic phosphate ester compound before adding the polythiol compound. This preliminary step creates a modified polyisocyanate composition that has reduced reactivity toward water, preventing premature reaction and viscosity increase when the final composition is prepared, thereby maintaining workability while preserving the high reactivity needed for polymerization.
Solution Approach 2:
The acidic phosphate ester compound acts as an intermediary substance that modifies the polyisocyanate compound. It forms a complex or adduct with the polyisocyanate, reducing its reactivity toward water while maintaining its reactivity toward the polythiol compound. This intermediary role allows the system to achieve both low viscosity (good workability) and high reactivity when needed.
2Reliability
If an alkyl tin halide compound is added in advance to a polyisocyanate compound to prevent water reaction, then polymerization catalyst function is provided, but the polyisocyanate compound deteriorates due to reaction with water in air or environment
Solution Approach 1:
The acidic phosphate ester compound serves as an intermediary that protects the polyisocyanate compound from water reaction. It forms a protective complex with the polyisocyanate, reducing its susceptibility to water attack. This intermediary protection is more effective and stable than using alkyl tin halide compounds, preventing deterioration while maintaining catalytic functionality.
Solution Approach 2:
The patent changes the chemical parameters of the polyisocyanate compound by introducing the acidic phosphate ester compound. This modification alters the reactivity parameters of the polyisocyanate, specifically reducing its reactivity toward water while maintaining or enhancing its reactivity toward the polythiol compound under polymerization conditions.
3Productivity
If a polyisocyanate compound with high reactivity toward polythiol is used, then polymerization efficiency is improved, but viscosity increases with time, causing difficulty in injection into mold
Solution Approach 1:
The patent applies preliminary action by pre-modifying the polyisocyanate compound with the acidic phosphate ester compound. This preliminary modification creates a stable composition that maintains low viscosity and good flow properties, enabling easy injection into molds. When the polythiol compound is added, the polymerization proceeds efficiently due to the maintained reactivity of the modified polyisocyanate.
Solution Approach 2:
The acidic phosphate ester compound acts as an intermediary that decouples the relationship between reactivity and viscosity. It modifies the polyisocyanate to reduce viscosity and improve flow characteristics, while maintaining the necessary reactivity for efficient polymerization when the polythiol compound is introduced.
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
This approach results in a polyurethane lens with improved workability and stability, maintaining transparency and refractive index while preventing premature gelation and degradation.
Implementation Method 1
polymerizing a composition containing (A) a polyisocyanate compound, (B) a polythiol compound
Implementation Method 2
a polythiol compound that is obtained through esterification reaction of a polyol compound and thioglycolic acid
Data Source
AI summary
Provided is a method for producing a polyurethane lens by polymerizing a composition containing a polyisocyanate compound and a specific polythiol compound having high reactivity, in which the method suffers less increase in viscosity with the lapse of time and thus is excellent in workability. The method for producing a polyurethane lens, contains polymerizing a composition containing (A) a polyisocyanate compound, (B) a polythiol compound containing a polythiol compound that is obtained through esterification reaction of a polyol compound and thioglycolic acid, (C) a polymerization catalyst, and from 0.001 to 0.5 part by mass per 100 parts by mass in total of the components (A) and (B) of (D) an acidic phosphate ester compound represented by the following general formula (1), in which the method contains a step of preparing the composition by mixing the components (A) and (D), and then adding the components (B) and (C) thereto: wherein in the general formula (1), R1 represents an alkyl group having from 1 to 20 carbon atoms or an aryl group having from 6 to 10 carbon atoms; a represents a number of from 0 to 2; and b represents a number of 1 or 2.