Microporous Membrane Dyeing for Dark Shades Without Pore Changes
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Solution Overview
Problem
Existing methods for dyeing microporous track etched membranes with large pores and low porosity struggle to achieve dark shades without altering membrane parameters or affecting cell culture applications, as they require high temperatures and solvent systems that are difficult to remove and can cause structural changes.
Innovation Solution
A method involving an aqueous dispersion dye system with azo and anthraquinone dyes, heated to 100°C for dyeing and then to 110-150°C for fixation, using a solvent to remove residual dye, which maintains membrane integrity and prevents diffusion into the polymer matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If disperse dyes in solvent systems with higher boiling alcohols or hydrocarbons are used to achieve dark shades, then the dyeing effectiveness is improved, but the solvent removal becomes difficult and negatively influences cell culture applications
Solution Approach 1:
The patent changes the solvent system parameters from high-boiling alcohols/hydrocarbons to low-boiling solvents (boiling point 40-120°C), specifically using mixtures like ethyl acetate/n-butanol/water that enable easy solvent removal while maintaining dark shade dyeing effectiveness in large pore membranes
Solution Approach 2:
The patent employs volatile solvents that evaporate completely after dyeing, leaving no harmful residues. The solvent system is designed to be temporarily present during processing then completely removed, eliminating long-term harmful effects on cell culture applications
2Illumination intensity
If relatively high temperatures exceeding the glass transition temperature of PET are employed to move dye molecules through polymer chains, then the dyeing effect is improved, but structural changes of the membrane material occur resulting in changes of pore diameter or surface roughness
Solution Approach 1:
The patent modifies the temperature parameter from above glass transition temperature (>80°C for PET) to below glass transition temperature (<80°C), achieving dark shade dyeing at 20-80°C without causing polymer chain mobility that would alter pore structure or surface roughness
Solution Approach 2:
The patent introduces specific solvent systems (ethyl acetate, n-butanol, water mixtures) that act as intermediaries to facilitate dye molecule transport through the membrane at lower temperatures, replacing the need for thermal energy that would otherwise cause structural changes
3Illumination intensity
If membranes with large pores and low porosity are dyed to achieve dark shades, then the light transmission blocking is improved, but the membrane material must be dyed much more intensively which requires more aggressive dyeing conditions
Solution Approach 1:
The patent changes multiple process parameters simultaneously: temperature (20-80°C), solvent composition (ethyl acetate/n-butanol/water ratios), and dye concentration (0.1-10 g/L), creating an optimized dyeing regime for large pore membranes that achieves dark shades without aggressive conditions
Solution Approach 2:
The patent adapts the dyeing approach by using solvent systems and temperature regimes specifically tailored for large pore membranes, copying the successful principles from small pore dyeing but modifying parameters to suit the different structural characteristics of large pore membranes
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 method effectively achieves dark shades with at least 90% reduction in light transmission, suitable for cell culture applications, without altering membrane parameters or causing structural changes, and is suitable for continuous roll-to-roll processing.
Implementation Method 1
achieves dark shades with at least 90% reduction in light transmission
Implementation Method 2
contacting the membrane with an aqueous dispersion dye system at a temperature between 90 to 100° C. and heating the membrane by exposing it to a temperature between 110 and 150° C.
Data Source
AI summary
Methods for dyeing of microporous track etched membranes are provided. In particular, these methods are suitable for dark shade dyeing of membranes having large pores with low porosity. Desirably, such methods provide dyed membranes wherein the membrane parameters are not significantly changed as compared to those prior to dyeing. Likewise, the resultant dyed membranes exhibit no negative influence on sensitive cell culture system applications.