Siloxane Block Copolymer Coatings for Water Repellency and Compatibility

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Solution Overview

Problem

Existing water-repellent coating materials, such as fluorine-based and silicone-based materials, face challenges in compatibility with other materials, adhesion, tensile strength, tear strength, and wear resistance, while fluorine-based materials are expensive and environmentally harmful.

Innovation Solution

A coating composition using a siloxane group-containing polymer, specifically a block copolymer with a siloxane group-containing vinyl monomer and a hydroxyl group-containing vinyl monomer, is crosslinked to form a stable coating film that retains water repellency and other properties without bleeding, achieved through living radical polymerization and a crosslinking agent.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fluorine-based materials are used for water repellency, then water repellency is improved, but cost and environmental harm increase

Engineering Contradiction:

Improvewater repellencyVSAvoidenvironmental pollution

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces expensive fluorine-based materials with cheaper silicone-based materials that can be applied in thinner layers, making the coating more economically viable and environmentally friendly while maintaining water repellency functionality

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the chemical composition parameters by using silicone-based materials with specific molecular structures (polymerizable unsaturated bonds and siloxane groups) to achieve the desired water repellency without the environmental harm associated with fluorine-based materials

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If silicone-based materials are used for water repellency, then ease of use is improved, but adhesion and mechanical strength deteriorate

Engineering Contradiction:

Improveease of useVSAvoidadhesion and mechanical strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent creates a composite material system by combining silicone-based materials with polymerizable unsaturated bonds and siloxane groups, allowing the material to participate in crosslinking reactions that form a network structure, thereby improving adhesion and mechanical strength while maintaining ease of application

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent introduces specific functional groups (polymerizable unsaturated bonds at chain ends and siloxane groups along the chain) at specific locations within the silicone polymer structure, enabling different regions of the material to perform different functions: crosslinking for strength and siloxane groups for water repellency

Inventive Principle:

Principle #3Local quality

3Reliability

If increased amount of silicone-based material is used for water repellency, then water repellency is improved, but compatibility with other materials deteriorates

Engineering Contradiction:

Improvewater repellencyVSAvoidcompatibility

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent optimizes the molecular structure parameters of the silicone-based material by controlling the placement of polymerizable unsaturated bonds at chain ends and siloxane groups along the chain, enabling effective water repellency at lower concentrations and improving compatibility with other coating materials

Inventive Principle:

Principle #35Parameter changes

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 coating composition provides long-lasting water repellency, reduces adhesion of oily substances, maintains tensile strength and wear resistance, and ensures compatibility with other materials, enhancing the durability of the coating film.

Implementation Method 1

the siloxane group-containing polymer is firmly incorporated in a coating film through a crosslinking reaction of the coating film

Methodology Applied

Scientific EffectCrosslinking reaction: Chemical Bonding

Implementation Method 2

a siloxane moiety imparting water repellency

Methodology Applied

Scientific EffectWater repellency: Hydrophobe

Implementation Method 3

when the siloxane group-containing polymer is a block copolymer, a moiety contributing to the crosslinking reaction of the coating film and a siloxane moiety imparting water repellency are separated in the polymer molecule

Methodology Applied

Scientific EffectBlock copolymer separation:

Data Source

PatentEP4212598B1Composition for coating materials

Publication Date: 2025.10.22 NIPPON PAINT AUTOMOTIVE COATINGS

Figure 1

AI summary

The present invention provides a water-repellent coating composition which enables easy removal of dirt while having good appearance due to high compatibility of a water-repellent component with other materials. The present invention provides a coating composition, comprising a siloxane group-containing polymer (A) and a crosslinking agent (B), wherein the siloxane group-containing polymer (A) is a block copolymer comprising an A block and a B block, and containing, in the A block, at least a structural unit derived from a siloxane group-containing vinyl monomer (a) and containing, in the B block, a structural unit derived from a hydroxyl group-containing vinyl monomer (b) and, as necessary, a structural unit derived from another vinyl monomer (c) copolymerizable with the vinyl monomers (a) and (b), and is a copolymer having a molecular weight distribution (Mw/Mn) of 2.0 or less and polymerized by living radical polymerization.