Zwitterionic Resin Surface Treatment Liquid for Hydrophilic Coating
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Solution Overview
Problem
Conventional surface treatment methods using copolymers with acrylamide and mono(meth)acrylate monomers can embed fine concave portions on surfaces, leading to reduced dimensions and increased susceptibility to contamination by organic substances, resulting in lowered hydrophilicity.
Innovation Solution
A surface treatment liquid containing a resin with a quaternary ammonium cation group and sulfonic acid anion group derived from N-substituted (meth)acrylamide, along with a reactive silyl group, is used, with a concentration less than 2 mass% and a pH of 4 or less, to form a firmly bonded, thin hydrophilic coating that resists separation and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copolymer surface treatment agents are used to make surfaces hydrophilic, then hydrophilicity is improved, but fine concave portions on the surface are embedded and dimensions are reduced
Solution Approach 1:
The invention changes the chemical structure parameters of the surface treatment agent by using zwitterionic polymers with specific repeating units containing both positive and negative charge groups, instead of conventional copolymers. This structural parameter change allows the agent to provide hydrophilicity without embedding into fine concave portions, thus resolving the contradiction between improving hydrophilicity and maintaining surface dimension precision.
2Reliability
If copolymer surface treatment agents are used, then hydrophilicity is improved, but the surface becomes contaminated with organic substances that are unlikely to be dissolved in water, lowering hydrophilicity
Solution Approach 1:
The invention changes the chemical properties of the surface treatment agent by employing zwitterionic polymers with unique amphiphilic characteristics that resist adsorption of organic substances. The specific repeating units with both cationic and anionic groups create a surface that is resistant to contamination by fats and other organic materials, thus maintaining hydrophilicity even after contamination exposure.
3Strength
If the surface treatment liquid concentration is increased to ensure coating stability, then coating firmness is improved, but the film thickness increases and separation becomes more likely
Solution Approach 1:
The invention changes the concentration parameter of the surface treatment liquid to less than 2 mass%, which is lower than conventional formulations. The zwitterionic polymer structure enables effective bonding and hydrophilic treatment even at this low concentration, producing a thin film that is firmly attached to the surface without prone to separation, thus resolving the contradiction between coating firmness and film thickness.
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 solution provides a stable, thin hydrophilic coating that maintains its hydrophilicity even after contact with fats, ensuring effective surface treatment for microchannel devices and similar surfaces.
Implementation Method 1
a terminal group comprising a silanol group and/or a reactive silyl group having a group to generate a silanol group by hydrolysis is bonded
Data Source
AI summary
An object is to provide a surface treatment liquid which can firmly bond, while coating the surface of a treatment target with an extremely thin film, a coating whose hydrophilicity is unlikely to be lowered even when the coating is brought into contact with fats and the like to the surface of the treatment target and a surface treatment method using the surface treatment liquid described above. In a surface treatment liquid containing a resin (A) and a solvent (S), as the resin (A), a resin is used which includes a constituent unit (a1) that includes an organic group including a quaternary ammonium cation group and having a sulfonic acid anion group at a terminal and that is derived from an N-substituted (meth) acrylamide, and includes a reactive silyl group in at least one of molecular chain terminals, the concentration of the resin (A) in the surface treatment liquid is less than 2 mass% and the pH of the surface treatment liquid is 4 or less.