Silane-Phosphate Polymer Latex for High-PVC Coating Durability
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Solution Overview
Problem
Existing latex paints with high pigment volume concentration (PVC) face challenges in achieving a balance between opacity, wet scrub resistance, and stability, often resulting in reduced mechanical stability and increased grit formation.
Innovation Solution
Aqueous polymer latexes produced through emulsion polymerization of specific monomers, including non-ionic monomers, hydrolysable silane groups, and acidic phosphate groups, with controlled particle size distribution, enhance binder performance by improving adhesion and cohesion, leading to stable, high-PVC paints with improved opacity and wet scrub resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods (ammonium persulfate/TEGMA or potassium persulfate/TEMED) are used to prepare aqueous polymer latex, then the polymerization process can be completed, but the resulting latex exhibits poor adhesion to substrates and limited resistance to alkaline conditions
Solution Approach 1:
The patent changes the chemical parameters of the polymerization system by substituting conventional initiators (ammonium persulfate/TEGMA or potassium persulfate/TEMED) with redox initiator systems comprising sodium persulfate and formaldehyde. This parameter change in the initiator chemistry directly improves the adhesion and alkaline resistance of the resulting polymer latex while maintaining manufacturing feasibility through a straightforward substitution process.
Solution Approach 2:
The invention creates a composite initiator system by combining sodium persulfate (oxidizing agent) and formaldehyde (reducing agent) to form a redox initiation system. This composite approach enables controlled polymerization while producing polymer latex with enhanced adhesion properties and alkaline resistance, overcoming the limitations of single-initiator conventional methods.
2Reliability
If redox initiators (sodium persulfate and formaldehyde) are used, then adhesion and alkaline resistance are improved, but the exothermic reaction during polymerization must be carefully controlled
Solution Approach 1:
The patent employs dynamic temperature control during polymerization, adjusting the polymerization temperature within the range of 40-80°C based on the exothermic nature of the redox reaction. This dynamic approach allows the reaction to proceed efficiently while preventing excessive temperature rise, thereby controlling the exothermic reaction and maintaining product quality with improved adhesion and alkaline resistance.
3Adaptability or versatility
If conventional initiators are used, then the polymerization process is simpler to control, but the resulting product has limited application scope and performance
Solution Approach 1:
By changing the initiator system parameters from conventional thermal initiators to a redox initiator system (sodium persulfate/formaldehyde), the patent achieves both improved product performance and expanded application scope. The redox mechanism enables better control over polymerization kinetics, resulting in polymer latex with superior adhesion and alkaline resistance suitable for more demanding applications, while the initiator system itself remains relatively simple to implement.
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 latex paints provide enhanced opacity and wet scrub resistance while maintaining stability, reducing grit formation, and do not require significant volatile filming auxiliaries, offering a cost-effective solution for high-PVC coatings.
Implementation Method 1
utilizing redox initiators comprising sodium persulfate and formaldehyde
Implementation Method 2
free radical polymerization of vinyl monomers
Data Source
AI summary
The present invention relates to aqueous polymer latexes of film-forming copolymer particles obtainable by aqueous emulsion polymerisation of monoethylenically monomers M, which mainly comprise non-ionic monomers of the group consisting of alkyl(meth)acrylates, cycloalkyl(meth)acrylates and monovinylaromatic hydrocarbon monomers and which additionally comprise 0.01 to 1% by weight, based on the total weight of monomers M, of at least one monoethylenically unsaturated monomer M2 having a hydrolysable silane group; and 0.1 to 2% by weight, based on the total weight of monomers M, of at least one monoethylenically unsaturated monomer M3 having an acidic phosphate group, or a salt thereof and where the copolymer particles in the polymer latex have volume median particle diameter of at least 250 nm, as determined by dynamic light scattering according to the ISO 13321:1996 standard. The polymer latexes are particularly suitable as binders in coating compositions having high pigment volume concentration (PVC) of preferably above 60% and provide good wet scrub resistance and opacity to coatings obtained therefrom. The present invention also relates to a process for producing such polymer latexes, to waterborne coating compositions containing these latexes and to the use of said polymer latexes for improving the wet scrub resistance and the opacity of coating compositions having a pigment volume concentration (PVC) of preferably above 60%.