TiO2 Composite Hiding Efficiency via pH-Controlled Adsorption
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Solution Overview
Problem
Current pre-composite technologies for pigmented paints using highly reactive monomers like phosphoethylmethacrylate form grit during composite preparation with TiO2, requiring expensive high-shear mixing to control flocculation, while less reactive monomers result in reduced hiding efficiency.
Innovation Solution
A process involving a TiO2 slurry with a pH adjustment to 10-12 for 10 minutes before contacting it with adsorbing latex particles containing itaconic acid units, followed by pH lowering to 8.5-9, to form composites that reduce grit formation and enhance hiding efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If highly reactive functional monomers such as phosphoethylmethacrylate are used to prepare pre-composites, then hiding efficiency is improved, but grit formation occurs during composite preparation
Solution Approach 1:
The patent changes the chemical reactivity parameter of the monomer from highly reactive (phosphoethylmethacrylate) to less reactive (itaconic acid). This parameter change reduces the uncontrolled reaction with TiO2 that causes grit formation, while still achieving adequate hiding efficiency through the adsorption mechanism at controlled pH levels.
Solution Approach 2:
The patent introduces pH control as an intermediary mechanism to mediate between the pre-composite and TiO2. By maintaining specific pH ranges (6.5-8.0 during mixing, then adjusting to 9.0-11.0), the pH acts as a controlling intermediary that enables adsorption without causing uncontrolled reactions and grit formation.
2Object-generated harmful factors
If less reactive monomers such as itaconic acid are used to control grit, then hiding efficiency is reduced
Solution Approach 1:
The patent changes the environmental parameter (pH) to compensate for the lower reactivity of itaconic acid. By adjusting and maintaining pH at 9.0-11.0, the patent enhances the adsorption capability of the less reactive monomer, achieving both grit control and adequate hiding efficiency without requiring highly reactive monomers.
Solution Approach 2:
The patent performs preliminary pH adjustment before mixing the pre-composite with TiO2. By pre-adjusting the pH to the optimal range and maintaining it during the mixing process, the patent creates favorable conditions for adsorption to occur effectively, compensating for the lower inherent reactivity of itaconic acid.
3Object-generated harmful factors
If high shear mixing is used to control flocculation, then grit is reduced, but manufacturing cost increases
Solution Approach 1:
The patent introduces pH control as a chemical intermediary that prevents flocculation without requiring intense mechanical mixing. By maintaining pH at 6.5-8.0 during mixing, the pH acts as a protective intermediary that keeps the system stable, allowing mixing at lower shear rates and reducing equipment costs.
Solution Approach 2:
The patent replaces the need for expensive high-shear mixing equipment with a chemical control mechanism (pH adjustment). Instead of using intense mechanical energy to prevent flocculation, the patent uses chemical pH control to maintain system stability, substituting mechanical intensity with chemical parameter control.
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 process effectively minimizes grit formation and significantly improves hiding efficiency in pigmented paints, offering a cost-effective solution by using less reactive pre-composites with itaconic acid units, outcompeting dispersants for adsorption on TiO2 surfaces.
Implementation Method 1
adsorbing latex particles that have a greater affinity than the dispersant for TiO2
Implementation Method 2
the pH of the TiO2 slurry is maintained at 10 to 12 for at least 10 minutes before it is contacted with the adsorbing latex
Data Source
AI summary
The present invention relates to a process comprising the steps of a) contacting an aqueous dispersion of a TiO2 slurry containing adsorbing dispersant with an adsorbing latex to form a mixture, wherein the pH of the mixture of the TiO2 slurry and adsorbing latex are sufficiently high to inhibit interaction between the TiO2 and the adsorbing dispersant; then b) lowering the pH of the mixture of step a) sufficiently to promote interaction between the TiO2 and the adsorbing latex, thereby forming a composite; wherein the adsorbing latex comprises structural units of itaconic acid or a salt thereof. The process of the present invention provides for improved hiding and reduced grit for coatings compositions.