Polyester-Polyurethane Dispersion Adhesion to Plastics
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Solution Overview
Problem
Existing aqueous polyurethane dispersions for soft feel coating materials lack adequate adhesion to plastics substrates, requiring multi-coat systems and failing to meet both soft feel and adhesion requirements.
Innovation Solution
A process for preparing polyester-polyurethane resin dispersions involving specific polyol components with high aromatic carboxylic acid content, polyisocyanate reactions, and hydrophilic modification to enhance adhesion, allowing for single-coat applications with improved tactile properties and solvent resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If aqueous polyurethane dispersions are used for soft feel coating materials, then soft feel properties and tactile sensation are improved, but adhesion to plastics substrates deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the polyol components, specifically requiring at least 60 mol% aromatic carboxylic acid groups. This parameter change transforms the polyol structure to provide both soft feel properties and improved adhesion to plastics substrates simultaneously
Solution Approach 2:
The patent creates a composite polyol system combining polyester polyols with aromatic carboxylic acid groups and other polyol components (including polyether polyols with specific molecular weights). This composite approach achieves synergistic effects where the combination provides both soft feel and adhesion properties that individual components cannot achieve alone
2Reliability
If multi-coat systems with primer are used to improve adhesion, then adhesion to substrates is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent develops a polyol component that performs multiple functions simultaneously: providing soft feel properties, ensuring adhesion to plastics substrates, and enabling single-coat application. This multi-functional component eliminates the need for separate primer and basecoat layers, simplifying the coating system while maintaining adhesion
Solution Approach 2:
The patent merges the functions of primer and basecoat into a single coating layer by using polyols with aromatic carboxylic acid groups that provide both adhesion promotion and soft feel properties. This consolidation reduces the number of coating steps while achieving the desired adhesion and aesthetic properties
3Ease of manufacture
If conventional polyol components are used, then manufacturing simplicity is maintained, but adhesion properties and condensation resistance deteriorate
Solution Approach 1:
The patent specifies precise parameter requirements for the polyol components, particularly the aromatic carboxylic acid group content (at least 60 mol%). By controlling these parameters during manufacturing, the process remains straightforward while achieving superior adhesion and condensation resistance properties
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 dispersions provide excellent adhesion to plastics substrates and improved condensation resistance, enabling the use of single-coat systems with outstanding soft feel and low VOC emissions.
Implementation Method 1
reacting i) one or more polyol components having a number average molecular weight of at least 300 daltons, at least 60% by weight of component i) being a polyester polyol with the fraction of aromatic carboxylic acid groups relative to all of the carboxylic acid groups used to prepared said polyester polyol being at least 60 mol %, ii) optionally one or more polyol components having a number average molecular weight of 62 to 299 daltons, and iii) optionally a compound which is monofunctional for the purposes of the isocyanate polyaddition reaction... with iv) a polyisocyanate to form a prepolymer
Implementation Method 2
B) dissolving the prepolymer in an organic solvent
Implementation Method 3
D) precipitating the product from C) by adding water to form a dispersion
Implementation Method 4
E) removing the organic solvent
Data Source
AI summary
A process for preparing polyester-polyurethane resin dispersions comprising:A) reactingi) one or more polyol components having a number average molecular weight of at least 300 daltons, at least 60% by weight of component i) being a polyester polyol with the fraction of aromatic carboxylic acid groups relative to all of the carboxylic acid groups used to prepared said polyester polyol being at least 60 mol %,ii) optionally one or more polyol components having a number average molecular weight of 62 to 299 daltons, andiii) optionally a compound which is monofunctional for the purposes of the isocyanate polyaddition reaction and has an ethylene oxide content of at least 50% by weight and a number average molecular weight of at least 400 daltons, withiv) a polyisocyanate to form a prepolymer,B) dissolving the prepolymer in an organic solvent,C) reacting the prepolymer with v) one or more aliphatic and/or alicyclic primary and/or secondary polyamines having a number average molecular weight of 60 to 300 daltons, said polyamine optionally being in combination with hydrazine or hydrazine hydrate, and vi) a hydrophilicized aliphatic diamine,D) precipitating the product from C) by adding water to form a dispersion, andE) removing the organic solvent.