Aqueous Polymer Coating with Monohydrazide Crosslinker
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Solution Overview
Problem
Aqueous coating compositions face challenges in achieving improved water and alcohol resistance while maintaining good handling properties, particularly on black substrates, and balancing chemical resistance with flexibility and hardness requirements.
Innovation Solution
Incorporating a multiethylenically unsaturated aliphatic C5-C36 carboxylic acid monohydrazide into a keto-functionalized polymer composition, which acts as a crosslinker, to enhance water and alcohol resistance without compromising early block resistance, hardness, and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyhydrazides are used as crosslinkers in aqueous coating compositions, then water resistance and alcohol resistance can be achieved, but early block resistance deteriorates and handling properties worsen
Solution Approach 1:
The invention changes the chemical structure parameters of the crosslinker by using monohydrazides with specific carbon chain lengths (C5-C36) and unsaturation levels, rather than conventional polyhydrazides. This parameter change enables the crosslinker to provide water and alcohol resistance while maintaining early block resistance, as the specific molecular structure allows for controlled crosslinking density and flexibility in the coating film.
Solution Approach 2:
The invention creates a composite crosslinking system by combining the keto-functionalized polymer with monohydrazide crosslinkers. This composite approach allows the polymer to provide the base film properties while the monohydrazide crosslinkers provide chemical resistance, achieving a balance between water resistance, early block resistance, and handling properties that neither component could achieve alone.
2Reliability
If crosslinking density is increased to improve water and alcohol resistance, then chemical resistance improves, but flexibility and hardness balance deteriorates
Solution Approach 1:
The invention optimizes the crosslinking parameters by selecting monohydrazides with specific carbon chain lengths (C5-C36) and unsaturation levels. Longer carbon chains and appropriate unsaturation provide flexibility to the crosslinked network, while still maintaining sufficient crosslinking density for alcohol resistance. This parameter optimization allows the coating to achieve both chemical resistance and flexibility simultaneously.
3Reliability
If water resistance is improved on black substrates, then chemical resistance improves, but handling properties and early block resistance worsen
Solution Approach 1:
The invention changes the crosslinker molecular parameters to monohydrazides with specific chain lengths and unsaturation, which provide adequate crosslinking for water resistance on black substrates while maintaining film flexibility and early block resistance. The specific structural parameters prevent excessive crosslinking that would cause brittleness and poor handling 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 aqueous polymer composition provides coatings with improved water resistance, alcohol resistance, and maintained early block resistance, achieving a water resistance rating of 4 or higher and pencil hardness of HB or harder, suitable for various coating applications.
Implementation Method 1
a multiethylenically unsaturated aliphatic C5-C36 carboxylic acid monohydrazide... which acts as a crosslinker
Data Source
AI summary
An aqueous polymer composition comprising a multiethylenically unsaturated carboxylic acid monohydrazide and a keto-functionalized polymer, and an aqueous coating composition comprising such aqueous polymer composition and providing coatings with improved water resistance and alcohol resistance without compromising early block resistance.