Liquid repellent composition, liquid repellent processing method, and article having liquid repellent film
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Solution Overview
Problem
Conventional liquid repellents using crystallizable polyfluoroalkyl group-containing polymers face issues such as hard and brittle coatings, poor durability, and adverse effects on soft fibers due to high melting points, along with environmental concerns from using strong solvents.
Innovation Solution
A liquid repellent composition comprising a specific copolymer blend with a mass ratio of polymerized units that balances liquid repellency and durability, using a polyfluoroalkyl group-containing monomer with a hydrocarbon group and a cross-linkable functional group, along with surfactants to improve adhesion and reduce solvent use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a crystallizable polyfluoroalkyl group-containing polymer is used to achieve water and oil repellency, then liquid repellency is improved, but the coating becomes hard and brittle
Solution Approach 1:
The invention uses a composite polymer system comprising a polyfluoroalkyl group-containing polymer (providing liquid repellency) combined with at least one other polymer component. This composite approach allows the polyfluoroalkyl polymer to form fine crystals on the surface for water and oil repellency while the additional polymer components maintain coating flexibility and prevent brittleness, thus resolving the contradiction between liquid repellency and coating flexibility.
Solution Approach 2:
The invention achieves different properties at different locations within the coating system. The polyfluoroalkyl groups orient themselves at the surface to create a low-energy surface with high liquid repellency, while the bulk coating composition is formulated to remain flexible through the inclusion of additional polymer components. This local differentiation of properties resolves the contradiction between surface liquid repellency and bulk coating flexibility.
2Reliability
If a crystallizable polyfluoroalkyl group-containing polymer with high melting point is used, then water and oil repellency is improved, but durability against laundering and abrasion deteriorates
Solution Approach 1:
The composite polymer system combines a polyfluoroalkyl group-containing polymer with additional polymer components that provide durability. The polyfluoroalkyl polymer provides the necessary liquid repellency through surface orientation of Rf groups, while the additional polymer components enhance durability against laundering and abrasion, thus resolving the contradiction between liquid repellency and durability.
3Reliability
If strong solvents are used to process the liquid repellent composition, then coating performance is improved, but environmental harm increases
Solution Approach 1:
The invention changes the solvent parameter from strong organic solvents to water or weak solvents. The liquid repellent composition is formulated to be processable in water or weak solvents while still achieving the necessary coating performance through the polymer composition and fine crystal formation of polyfluoroalkyl groups, thus resolving the contradiction between coating performance and environmental harm.
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 composition provides excellent liquid repellency and durability while maintaining softness and adhesion, and is environmentally friendly by using a water-based or weak solvent system, effectively addressing the limitations of previous technologies.
Implementation Method 1
formation of 'a low energy surface' having a low critical surface tension on the surface of a coating film by surface orientation of Rf groups
Implementation Method 2
water and oil repellency... attributable to Rf groups
Implementation Method 3
fine crystals derived from Rf groups... a polymer has a melting point attributable to fine crystals derived from Rf groups
Data Source
AI summary
To provide a liquid repellent composition which is excellent in liquid repellency and durability and an article having a liquid repelling film. A liquid repellent composition comprising a copolymer (I) and a copolymer (II), characterized in that the copolymer (I) containing from 65 to 95 mass % of a polymerized unit (a) (referred to as “[a1]”) and from 1 to 30 mass % of a polymerized unit (b); and the copolymer (II) containing from 25 to 80 mass % of a polymerized unit (a) (referred to as “[a2]”) and from 1 to 50 mass % of a polymerized unit (c) are contained in an amount of the copolymer (I)/the copolymer (II)=10/90 to 95/5 (mass ratio), and [a1]−[a2]≧10 (mass %).