Aqueous Vinyl Coating Composition for Stable One-Pack Crosslinking
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Solution Overview
Problem
Existing aqueous coating compositions face issues with viscosity instability and poor application properties, particularly in one-package systems, which affect the hardness and chemical resistance of coatings, and there is a need for improved viscosity stability and application properties while maintaining low minimal film-formation temperature (MFFT).
Innovation Solution
A crosslinkable aqueous vinyl polymer composition is developed, comprising a crosslinkable oligomer stabilized dispersion and a non-oligomer stabilized dispersion, with specific monomer combinations and crosslinkers to enhance stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a one-package system with pre-combined polymer dispersion and crosslinker is used, then ease of operation is improved, but viscosity stability deteriorates upon storage
Solution Approach 1:
A carbonyl-reactive polymer is introduced as an intermediary component that mediates between the carbonyl-functional oligomer and the crosslinker. This polymer reacts with the crosslinker to form a stable complex during storage, preventing premature crosslinking and viscosity instability, while still allowing the crosslinking reaction to proceed when the coating is applied and dried.
2Ease of operation
If carbonyl-functional oligomer and crosslinker are pre-combined in one-package system, then application convenience is improved, but reaction stability during storage deteriorates
Solution Approach 1:
The carbonyl-reactive polymer serves as a stabilizing intermediary that controls the reaction between the carbonyl-functional oligomer and crosslinker during storage. It forms stable intermediates that prevent unwanted crosslinking reactions, ensuring reliability and shelf stability while maintaining the intended crosslinking capability for application.
Solution Approach 2:
The system utilizes changes in reaction parameters (temperature, moisture, concentration) to control reactivity. During storage at ambient conditions, the carbonyl-reactive polymer dominates the interaction with the crosslinker. Upon application and drying, changes in temperature and moisture drive the intended crosslinking reaction between the carbonyl-functional oligomer and crosslinker.
3Object-generated harmful factors
If organic co-solvents are reduced in waterborne coatings, then environmental compliance is improved, but minimal film-formation temperature increases
Solution Approach 1:
The patent utilizes crosslinking chemistry to change the fundamental parameters of film formation. By introducing carbonyl-functional oligomers that react with crosslinkers to form crosslinked networks, the system achieves film formation at lower temperatures without relying on organic co-solvents, thus maintaining environmental compliance while lowering MFFT.
4Strength
If crosslinking mechanism is introduced to increase hardness, then coating hardness is improved, but formulation complexity increases
Solution Approach 1:
The patent merges multiple functions into the carbonyl-reactive polymer component. It simultaneously provides viscosity stabilization during storage, controls the crosslinking reaction rate, and enables the hardening mechanism. This consolidation reduces formulation complexity compared to using separate additives for each function while maintaining improved coating hardness.
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 composition achieves improved viscosity stability, retention of gloss, and early water resistance, along with better application properties and hardness, addressing the limitations of existing systems.
Implementation Method 1
the hydrazide groups react with carbonyl groups by a condensation reaction to form hydrazone linking bonds between the polymer chains
Implementation Method 2
Removal of water from the system, such as by evaporation during air drying, drives the reaction towards the crosslinked product
Data Source
AI summary
The present invention relates to crosslinkable aqueous vinyl polymer composition comprising from 70 to 97.5 weight % of a crosslinkable oligomer stabilized dispersion PD1 of vinyl polymer P1, PD1 comprising a water-soluble or water-dispersible crosslinkable oligomer OL and at least one high molecular weight vinyl polymer P1 prepared in the presence of the water-soluble or water-dispersible crosslinkable oligomer OL; from 2 to 29.5 weight % of at least one non-oligomer stabilized dispersion PD2 of vinyl polymer P2; and from 0.5 to 28 weight % of at least one crosslinker X, and its use in coating compositions.