Water/Oil Repellent Coating for Waterproof Fabric Adhesion
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Solution Overview
Problem
Existing water/oil repellent compositions for fabrics face issues with coating liquid penetration and adhesion of moisture-permeable waterproofing films, leading to design impairments and environmental concerns due to the use of perfluoroalkyl groups.
Innovation Solution
A water/oil repellent composition comprising a specific copolymer blend with monomers such as C4-6 polyfluoroalkyl groups, vinylidene chloride, and crosslinkable functional groups, applied to one side of a porous substrate to form a moisture-permeable waterproofing film, which suppresses coating liquid penetration and enhances adhesion while minimizing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating liquid is applied to the rear side of fabric treated with conventional water/oil repellent composition to form a moisture-permeable waterproofing film, then the fabric gains waterproofing function, but the coating liquid penetrates to the front surface side of the fabric and a resin film is formed on the front surface side, impairing the design of the article
Solution Approach 1:
The patent applies local quality by creating asymmetric surface properties: the front surface uses a water/oil repellent composition with specific fluorinated copolymer units to prevent coating liquid penetration and maintain design appearance, while the rear surface allows waterproofing film formation. This directional control ensures the coating liquid acts differently on each surface based on functional requirements.
Solution Approach 2:
The patent employs parameter changes by specifying precise compositional parameters of the water/oil repellent composition, including the molar ratio of fluorinated copolymer units (at least 1:1 ratio of units from monomers with 7-10 carbon atoms to units from monomers with 3-6 carbon atoms), to create optimal surface properties that prevent coating liquid penetration while maintaining waterproofing functionality.
2Reliability
If a coating liquid is applied to the rear side of fabric treated with water/oil repellent composition to form a moisture-permeable waterproofing film, then waterproofing function is achieved, but the adhesion between the fabric and the waterproofing film is insufficient causing film peeling
Solution Approach 1:
The patent uses composite materials by combining multiple copolymer components with specific fluorinated units and crosslinkable functional groups. This composite structure provides both waterproofing capability and strong adhesion to the fabric substrate, preventing film peeling while maintaining moisture permeability.
Solution Approach 2:
The patent applies preliminary action by pre-treating the fabric with a specifically formulated water/oil repellent composition containing crosslinkable functional groups before applying the waterproofing film. This preliminary treatment creates optimal bonding conditions that enhance adhesion strength and prevent film peeling during subsequent use.
3Reliability
If a water/oil repellent composition comprising copolymer with perfluoroalkyl groups having at least 7 carbon atoms is used, then water/oil repellency is achieved, but the composition presents high environmental impact due to decomposition and accumulation of perfluoroalkyl compounds
Solution Approach 1:
The patent applies parameter changes by precisely controlling the carbon atom count parameters of the perfluoroalkyl groups in the copolymer units, specifying that they have at least 7 carbon atoms. This parameter specification optimizes the balance between achieving sufficient water/oil repellency and managing environmental impact through controlled decomposition behavior.
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 fabrics with favorable water/oil repellency, wash durability, and reduced environmental impact by preventing coating liquid penetration and film peeling, maintaining design integrity and ecological sustainability.
Implementation Method 1
a copolymer having units based on a monomer having a polyfluoroalkyl group... to impart water/oil repellency
Implementation Method 2
a copolymer having units based on a monomer having a polyfluoroalkyl group... to impart water/oil repellency
Implementation Method 3
units based on the following monomer (c), and units based on the following monomer (d)... monomer (c): a vinyl ether having no Rf group and having a crosslinkable functional group
Data Source
AI summary
It is possible to obtain a porous substrate having a water/oil repellent-treated surface and a moisture-permeable waterproofing film, which has favorable water/oil repellency and wash durability, through which penetration of a coating liquid for formation of the moisture-permeable waterproofing film is suppressed, and from which peeling of the moisture-permeable waterproofing film is suppressed. A water/oil repellent composition comprising a copolymer (A) having from 60 to 95 mass % of units based on a monomer having a RF group having at most 6 carbon atoms and from 5 to 40 mass % of units based on vinylidene chloride, a copolymer (B) having from 50 to 95 mass % of units based on a halogenated olefin and from 5 to 50 mass % of units based on a monomer having a crosslinkable functional group, and a medium (C), wherein the proportion of the copolymer (A) is from 70 to 90 mass %, and the proportion of the copolymer (B) is from 10 to 30 mass %.