Method for conferring durable water repellence to woven or non-woven fabric and water repellent composition
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Solution Overview
Problem
Existing methods for conferring durable water repellence to fabrics rely on fluorocarbon-based treatments that are toxic and have short lifespans, or require fluorine-free coatings that degrade quickly, while also avoiding the use of silicone, isocyanates, and melamine boosters.
Innovation Solution
A method involving treatment with an aqueous composition containing an acrylic ester and a water miscible solvent with functional OH groups, followed by heat treatment to initiate a (trans)esterification reaction, resulting in hydrophobic moieties bound to the fabric through hydrogen bridging, without the use of fluorine, silicone, or melamine compounds, and optionally incorporating a polyisocyanate for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If fluorocarbon-based treatments are used to confer water repellence, then water repellence durability is improved, but environmental toxicity increases
Solution Approach 1:
The invention extracts and removes the harmful fluorocarbon components from the water repellent treatment, replacing them with non-toxic alternatives such as hydrocarbons, silicones, or waxes that provide similar water repellent functionality without environmental persistence and toxicity
Solution Approach 2:
The invention accepts that fluorocarbon-based treatments have short functional lifespans (degrading after limited washing cycles) and seeks alternative materials that can be applied repeatedly without cumulative environmental harm, prioritizing renewable application over permanent durability
2Object-affected harmful factors
If fluorine-free coatings are used to eliminate toxicity, then environmental safety is improved, but water repellence durability deteriorates
Solution Approach 1:
The invention uses composite material systems combining multiple non-fluorinated components (hydrocarbons, silicones, waxes, or polymers) that work synergistically to achieve both environmental safety and durable water repellence, where the combination provides enhanced durability compared to single-component fluorine-free treatments
Solution Approach 2:
The invention modifies the chemical and physical parameters of the coating materials, such as molecular weight, crosslinking density, and surface energy, to optimize the balance between durability and environmental safety for fluorine-free water repellent systems
3Reliability
If silicone, isocyanates or melamine boosters are used to enhance water repellence, then water repellence performance is improved, but coating complexity and potential toxicity increase
Solution Approach 1:
The invention removes silicone, isocyanates, and melamine compounds from the coating formulation, achieving water repellence through simpler base materials alone, thereby reducing compositional complexity and eliminating potentially harmful substances while maintaining functional performance
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 achieves a highly durable and sustainable water repellent coating that remains effective after 100 washing cycles, with improved stability when polyisocyanate is used, maintaining water and oil repellence without wear, even after repeated washing and drying.
Implementation Method 1
By the heat treatment step ii), a (trans)esterification reaction is initiated between a water miscible solvent molecule and the acrylic ester. A covalent C—O—C bond is formed between one of the at least two OH groups of the water miscible solvent molecule and with the oxygen of the C═O group of the acrylic ester
Implementation Method 2
the acrylic ester acquires a functional OH group, enabling the said ester to bond with the fabric fibre by this OH group through hydrogen bridging
Implementation Method 3
By the heat treatment step ii), a (trans)esterification reaction is initiated between a water miscible solvent molecule and the acrylic ester
Data Source
AI summary
Disclosed is a method for conferring durable water repellence to woven or non-woven fabric, comprising the steps of: (1) treating the fabric with an aqueous composition, the composition comprising (a) an aqueous solvent comprising at least 80 w/w % water, and 20 w/w % or less of a water miscible organic solvent comprising at least two functional OH groups, and (b) 0.1-40 w/w % of an acrylic ester having the formula 1: wherein A1 is H or CH3, and A2 is C1-C30 linear or branched, saturated or unsaturated hydrocarbon that may have an alicyclic or aromatic ring, the acrylic ester being dissolved, emulsified or dispersed in the aqueous solvent, (2) heating the treated fabric to 120-200° C. Further such a composition and fabric treated with such a composition are disclosed.