Multistage Polyvinyl Ester Coatings for Weathering Resistance

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Solution Overview

Problem

Existing coating compositions based on polyvinyl ester binders face challenges in achieving high weathering resistance, low reemulsification, water spot resistance, and high adhesive tensile strength, particularly in forming films with low water absorption and no snail trails.

Innovation Solution

The development of multistage polyvinyl ester dispersions prepared by polymerizing vinyl esters with specific monomers and initiators, including ethylenically unsaturated silane and epoxide units, in the presence of minimal protective colloids and emulsifiers, to create coatings with enhanced properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If polyvinyl ester binders are used in coating compositions, then cost-effectiveness and ease of manufacture are improved, but weathering resistance and durability are insufficient compared to polyacrylate binders

Engineering Contradiction:

Improveease of manufactureVSAvoidweathering resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent creates composite polymer dispersions combining polyvinyl ester with other polymer components (polyacrylate, polyacrylic acid, or polyvinyl alcohol) to achieve weathering resistance comparable to pure polyacrylate systems while maintaining the cost advantages of polyvinyl ester. The composite structure allows synergistic properties where the polyvinyl ester provides cost-effectiveness and the additional polymer components enhance weathering resistance and durability.

Inventive Principle:

Principle #40Composite materials

2Device complexity

If conventional single-stage polymerization is used, then process simplicity is maintained, but copolymerization of incompatible monomers is difficult and results in separate homopolymers rather than copolymers

Engineering Contradiction:

Improveprocess simplicityVSAvoidcopolymer formation

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The patent divides the polymerization process into multiple stages, with each stage targeting specific monomer combinations. The first stage polymerizes vinyl ester with compatible monomers, while subsequent stages introduce incompatible monomers under controlled conditions. This segmentation allows incompatible monomers to be copolymerized successfully without requiring complex one-stage processes, achieving both composition stability and reasonable process complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary polymerization of certain monomer combinations before introducing incompatible monomers. By pre-forming polymer chains with compatible monomers first, the system creates a foundation that facilitates subsequent copolymerization of incompatible monomers, ensuring proper copolymer formation rather than separate homopolymers.

Inventive Principle:

Principle #10Preliminary action

3Strength

If high proportions of acrylic acid or maleic anhydride are used to improve adhesion, then adhesive tensile strength is enhanced, but film viscosity increases significantly

Engineering Contradiction:

Improveadhesive tensile strengthVSAvoidfilm viscosity

Core Design Contradiction:

StrengthVSStress or pressure

Solution Approach 1:

The patent carefully controls the proportion of acidic monomers (acrylic acid or maleic anhydride) within specific ranges (0.1-10% by weight) to achieve adequate adhesive tensile strength while preventing excessive viscosity increase. By optimizing these parameter ranges and adjusting molecular weight and crosslinking density, the system balances adhesion performance with processability and application characteristics.

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 resulting coatings exhibit exceptionally high shade stability, low screen residues, and improved weathering resistance comparable to emulsion paints using polyacrylate binders, with films showing superior durability and resistance to outdoor weathering.

Implementation Method 1

monomer mixtures are converted by free-radical polymerization by addition of initiators

Methodology Applied

Scientific EffectFree-radical polymerization: Chemical Bonding

Implementation Method 2

polymerization can be effected in one or more stages in the presence of protective colloids and/or emulsifiers

Methodology Applied

Scientific EffectEmulsion stabilization: Colloid

Data Source

PatentUS9175185B2Coating compositions having high weathering resistance, process for preparation thereof and use thereof

Publication Date: 2015.11.03 CELANESE SALES GERMANY

AI summary

What are described are coating compositions comprising pigments and/or fillers and multistage polyvinyl ester dispersions as binders. These binders are produced by a selected multistage process in which a polyvinyl ester dispersion is obtained in a first stage, monomers in dissolved or pure form or in the form of an emulsion are added to the reaction mixture in a second stage and then the polymerization is started again. The polyvinyl ester dispersions comprise polymerized silanes and/or epoxides or the polyvinyl ester dispersions have only a small content of protective colloids, if any. The coating compositions formulated with the multistage polyvinyl ester dispersions obtained in this way are notable for a very high weathering resistance.