Aqueous Polymer Coating Composition for Carbon Black Corrosion Resistance
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Solution Overview
Problem
Existing aqueous polymer compositions, particularly black paints, face challenges in achieving excellent corrosion resistance and early water resistance due to the difficulty in dispersing carbon black, which requires high amounts of hydrophilic additives that compromise anti-corrosion performance, and they are inadequate for direct-to-metal coatings in rainy areas.
Innovation Solution
A novel aqueous polymer composition comprising a specific emulsion polymer with structural units of cycloalkyl (meth)acrylate, acetoacetoxy or acetoacetamide functional monomer, phosphorous acid monomer, and a waterborne resin with a fatty acid ester segment, providing coatings with enhanced corrosion resistance and early water resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If large amounts of hydrophilic additives are added to facilitate wetting and dispersing of carbon black, then dispersion quality is improved, but anti-corrosion performance deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the polymer by incorporating specific functional monomers (acetoacetoxy or acetoacetamide functional monomers at 0.1-10 wt%, phosphorous acid monomers at 0.05-10 wt%) that provide both dispersion capability and corrosion resistance. This parameter change allows the system to achieve both good carbon black dispersion and maintained anti-corrosion performance without needing large amounts of hydrophilic additives
Solution Approach 2:
The invention creates a composite polymer system combining multiple functional units within the same polymer chain: cycloalkyl (meth)acrylate units for water resistance, acetoacetoxy/acetoacetamide units for metal coordination and corrosion protection, and phosphorous acid units for additional corrosion inhibition. This composite structure enables the polymer to simultaneously provide dispersion, water resistance, and anti-corrosion properties
2Object-affected harmful factors
If conventional aqueous polymer compositions are used for direct-to-metal coatings in rainy areas, then environmental friendliness is improved, but water resistance deteriorates due to blisters
Solution Approach 1:
The invention modifies the polymer composition parameters by including cycloalkyl (meth)acrylate structural units (5-28 wt%) which provide enhanced hydrophobicity and water resistance. The specific ratio and type of monomers are optimized to create a polymer matrix that resists water penetration and blister formation while maintaining aqueous formulation environmental benefits
Solution Approach 2:
The polymer acts as an intermediary between the hydrophilic aqueous formulation and the hydrophobic requirement for water resistance. The specific polymer structure with cycloalkyl groups and functional monomers creates a bridging effect, allowing the aqueous coating to achieve solvent-borne level water resistance without using organic solvents
3Ease of manufacture
If ball mill or sand mill is used for carbon black dispersion, then traditional processing is maintained, but dispersion quality in water deteriorates compared to organic solvents
Solution Approach 1:
The invention changes the chemical parameters of the dispersing medium by using a specifically designed aqueous polymer with functional monomers that actively interact with carbon black surfaces. The acetoacetoxy/acetoacetamide and phosphorous acid groups provide coordination sites that enhance carbon black wetting and dispersion in water, achieving dispersion quality comparable to or better than organic solvent systems while using conventional milling equipment
Data Source
AI summary
An aqueous polymer composition comprises (A) a specific emulsion polymer comprising structural units of a cycloalkyl (meth)acrylate, structural units of an acetoacetoxy or acetoacetamide functional monomer, and structural units of a phosphorous acid monomer, a salt thereof, or mixtures thereof; and (B) a specific amount of a waterborne resin comprising at least one fatty acid ester segment and having a number average molecular weight of 20,000 g/mol or less, based on the total dry weight of the emulsion polymer and the waterborne resin. A coating composition comprising such aqueous polymer composition provides coatings made therefrom with improved anti-corrosion property.