Coating Composition Viscosity and Stability for Acid-Labile Compounds
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Solution Overview
Problem
Existing film coating compositions with enhanced moisture barrier properties have high viscosity, which is disadvantageous for spray coating applications and can negatively affect the stability of acid-labile compounds due to the presence of pH-dependent polymers.
Innovation Solution
A coating composition comprising at least 20% polyvinyl alcohol and 0.1 to 20% water-insoluble (meth)acrylate copolymer with quaternary ammonium groups, achieving a viscosity of 200 mPa·s or less, which improves sprayability and stability of acid-labile compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polymer with pH dependent solubility is used in the coating composition, then moisture barrier properties are enhanced, but viscosity increases and stability of acid labile compounds is compromised
Solution Approach 1:
The patent removes the pH-dependent polymer component from the coating composition, extracting only the necessary moisture barrier functionality through alternative means (polyvinyl alcohol-based system with specific additives), thereby eliminating the viscosity and stability problems associated with pH-dependent polymers while maintaining moisture protection
Solution Approach 2:
The patent creates a composite coating system combining polyvinyl alcohol with specific additives (surfactants, plasticizers, pigments) to achieve moisture barrier properties without relying on pH-dependent polymers, resulting in a composition that maintains low viscosity and compatibility with acid-labile compounds
2Reliability
If a polymer with pH dependent solubility is used in the coating composition, then moisture barrier properties are enhanced, but stability of acid labile compounds deteriorates
Solution Approach 1:
The patent removes the pH-dependent polymer component from the coating composition, extracting only the necessary moisture barrier functionality through alternative means (polyvinyl alcohol-based system with specific additives), thereby eliminating the viscosity and stability problems associated with pH-dependent polymers while maintaining moisture protection
Solution Approach 2:
The patent creates an inert coating environment using polyvinyl alcohol and neutral additives that do not interact chemically with acid-labile compounds, preventing degradation and impurity formation while still providing effective moisture barrier protection
3Reliability
If high viscosity coating composition is used, then moisture barrier properties are maintained, but spray coating efficiency decreases
Solution Approach 1:
The patent modifies the rheological parameters of the coating composition by selecting polyvinyl alcohol with specific molecular weight and degree of hydrolysis, and by optimizing additive concentrations, achieving a balance between moisture barrier performance and sprayability with viscosity of 200-500 cP
Solution Approach 2:
The patent introduces surfactants and plasticizers as intermediary substances that reduce intermolecular forces between polymer chains, lowering viscosity and improving flow characteristics for spray coating while maintaining the moisture barrier functionality of the polyvinyl alcohol matrix
Data Source
AI summary
The invention refers to a coating composition which, calculated on dry weight, is comprising at least 20 % by weight polyvinyl alcohol and 0.1 to 20 % by weight, calculated on the weight of the polyvinyl alcohol, of a water-insoluble (meth)acrylate copolymer comprising quaternary ammonium groups, wherein the viscosity of an aqueous dispersion comprising that coating composition with 25 % (w/w) solid content at 22 °C is 200 mPa.s or less.