Functionalized Urethane Methacrylate Polymers for Low VOC Coalescence
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Solution Overview
Problem
Water-based coatings struggle to achieve complete coalescence and high block resistance without using organic solvents or substantial co-solvents, plasticizers, and coalescent aids, which are typically required for higher glass transition temperature polymers to form uniform films and prevent adhesion issues.
Innovation Solution
A low VOC latex coating composition incorporating urethane (meth)acrylate monomers with sterically available hydrogen bonding sites, allowing for high glass transition temperatures and low minimum film forming temperatures, forming homogeneous films without the need for co-solvents, plasticizers, or coalescent aids through hydrogen bonding between polymer particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If higher glass transition temperature polymers are used in water-based coatings, then block resistance and hardness are improved, but complete film formation requires organic solvents or co-solvents which increase VOC levels
Solution Approach 1:
The invention changes the chemical parameters of the polymer by incorporating urethane (meth)acrylate monomers with specific hydrogen bonding capabilities. This modifies the polymer's film formation mechanism to rely on hydrogen bonding rather than solvent plasticization, enabling high Tg polymers to form complete films at low temperatures without VOCs
Solution Approach 2:
The invention creates a composite polymer system combining urethane (meth)acrylate monomers with other vinyl monomers. This composite structure provides both the high Tg needed for block resistance and the hydrogen bonding capability needed for low-temperature film formation without solvents
2Manufacturing precision
If co-solvents, plasticizers, or coalescence aids are added to water-based coatings, then film formation is improved, but VOC levels increase and film performance may deteriorate
Solution Approach 1:
The invention extracts and eliminates the need for co-solvents, plasticizers, and coalescence aids by incorporating hydrogen bonding functionality directly into the polymer structure. The polymer self-plasticizes through intermolecular hydrogen bonding, removing the need for external additive substances
Solution Approach 2:
The polymer serves its own film formation needs through inherent hydrogen bonding sites. The urethane (meth)acrylate groups within the polymer chain provide the necessary plasticization and coalescence functions that would otherwise require separate additives, making the system self-sufficient
3Manufacturing precision
If lower glass transition temperature polymers are used in low VOC water-based coatings, then complete film formation is achieved, but block resistance decreases
Solution Approach 1:
The invention decouples the relationship between Tg and film formation temperature by introducing hydrogen bonding sites. This allows the polymer to have high Tg (for block resistance) while maintaining low film formation temperature (for complete coating) through a different mechanism than conventional polymers
4Manufacturing precision
If organic solvents are used to dissolve polymers, then uniform film formation is achieved, but VOC levels increase significantly
Solution Approach 1:
The invention replaces the solvent-based dissolution mechanism with a water-based emulsion system that uses hydrogen bonding for film formation. This substitutes the chemical mechanism of solvent-polymer interaction with a different mechanism based on polymer-polymer hydrogen bonding, eliminating organic solvents while maintaining film quality
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 film formation and block resistance with high glass transition temperatures and low minimum film forming temperatures, maintaining low VOC levels and eliminating the need for additional additives, resulting in a durable and adhesive coating.
Implementation Method 1
The urethane (meth)acrylate monomer provides about 4 to about 15 percent sterically available hydrogen bonding sites per urethane (meth)acrylate monomer
Data Source
AI summary
A coating composition is described that has good film forming and blocking properties in a composition that also has low or no VOCs. The coating compositions herein include functionalized urethane (meth)acrylate polymers that allow better film formation and particle coalescence while maintaining the low or no VOC levels. In one aspect, the coating compositions include functionalized polymers with a higher glass transition temperature (Tg) to aid in achieving good block resistance but a low minimum film forming temperature (MFFT) to achieve good particle coalescence and film formation all while being substantially free of co-solvents, coalescent aid and/or plasticizers.