Curable Coating with Siloxane Cross-Linking for Low-Temperature Waterproofing
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Solution Overview
Problem
Existing building exterior materials with waterproof liquid coatings have insufficient moisture permeability, especially at low temperatures, leading to issues like dew condensation and indoor air pollution due to the lack of elasticity and high plasticizer migration in cured films.
Innovation Solution
A curable composition containing a reactive silyl group-containing polyoxyalkylene polymer or (meth)acrylate polymer with a specific oxyethylene and oxypropylene repeating unit ratio, which forms a siloxane bond for cross-linking, providing improved water vapor permeability and reduced plasticizer migration in the cured film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a latex polymer (aqueous emulsion) is used as a waterproof coating material, then the coating material can be applied, but it requires a long time to form a coating film at low temperatures or high humidity, causing difficulty in application in winter
Solution Approach 1:
The patent changes the chemical composition parameters by replacing latex polymer with reactive silyl group-containing polymers (silicone resin, polyurethane resin, or acrylic resin). This compositional parameter change enables the coating to cure through siloxane bond formation and cross-linking reactions that proceed effectively at low temperatures, eliminating the slow film formation issue of latex-based coatings in cold conditions
Solution Approach 2:
The patent employs composite material strategies by combining reactive silyl group-containing polymers with specific plasticizers and silane coupling agents. This composite formulation creates a synergistic system where the polymer matrix provides structural integrity while plasticizers maintain flexibility and enable low-temperature application, resolving the contradiction between ease of operation and time consumption
2Reliability
If a latex polymer coating film is used, then the coating can be formed, but it lacks elasticity, causing cracks or fracture and decrease in waterproofness over time
Solution Approach 1:
The patent fundamentally changes the material parameters by selecting polymers with inherent elastic properties (silicone resin, polyurethane resin, acrylic resin) and incorporating plasticizers in specific amounts (5-50 parts by weight per 100 parts polymer). This parameter optimization ensures the cured coating maintains high elasticity (elongation ≥50%) while achieving durable waterproofness through cross-linked siloxane bonds
Solution Approach 2:
The patent creates a composite material system combining elastic polymer matrices with plasticizers and cross-linking agents. This composite structure provides both the required elasticity for long-term durability and the cross-linked network for reliable waterproofing, eliminating the brittleness issue of conventional latex coatings
3Reliability
If conventional waterproof liquid coating materials are used, then waterproofing can be achieved, but moisture permeability is insufficient, leading to dew condensation and indoor air pollution
Solution Approach 1:
The patent optimizes the chemical composition parameters by selecting specific polymers with appropriate molecular structures and incorporating plasticizers that enhance free volume and molecular mobility. This parameter tuning allows the coating to maintain a balanced structure with sufficient cross-linking for waterproofing while having enough free space for water vapor transmission, achieving both waterproofing reliability and moisture permeability
Solution Approach 2:
The patent effectively creates a porous or microvoid structure through the use of plasticizers and the cross-linking network formation. This micro-porosity allows water vapor molecules to pass through the coating layer, providing moisture permeability while the continuous polymer matrix and cross-links maintain the waterproof barrier against liquid water, preventing dew condensation and indoor pollution
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 enables a building exterior material with enhanced water vapor permeability and elasticity, allowing for seamless waterproofing even at low temperatures, preventing indoor air pollution and maintaining physical properties like high elongation and strength in the cured film.
Implementation Method 1
a curable composition containing a polyoxyalkylene polymer containing a silicon-containing group which contains a hydroxyl or hydrolyzable group bonded to a silicon atom and can form a siloxane bond to be cross-linked
Implementation Method 2
cross-linked by siloxane bond formation involving hydrolysis or other reactions of the reactive silyl group due to factors such as moisture
Data Source
AI summary
The invention aims to provide a building exterior material in which a curable composition which has excellent water vapor permeability, can be applied at low temperatures, and shows less migration of plasticizers to a surface of a cured product is applied to a building exterior substrate. The building exterior material comprises a building exterior substrate coated with a curable composition comprising an organic polymer (A) containing a silicon-containing group capable of being cross-linked by forming a siloxane bond, wherein the organic polymer (A) is a polyoxyalkylene polymer (A1) containing an oxyethylene repeating unit in a backbone skeleton, a weight of the oxyethylene repeating unit in the component (A1) being 1 to 80% by weight of the total weight of the component (A1), and/or a (meth)acrylate polymer (A2) containing an oxyethylene repeating unit at a side chain, a weight of the oxyethylene repeating unit in the component (A2) being 1 to 50% by weight of the total weight of the component (A2) ; and the curable composition is cured into a cured product having a thickness of 0.1 to 3.0 mm.