Core-Sheath-Shell Polymer Particles Opacity via Base Swelling
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Solution Overview
Problem
Existing processes for producing core-sheath-shell polymer particles with high opacity values rely on toxic, expensive polymerization inhibitors and complex operations, which are undesirable and inefficient.
Innovation Solution
A process involving emulsion polymerization of a core, sheath, and shell, using a water-soluble catalyst within specific limits, and neutralizing with a volatile or fixed base in the presence of a monomer-solvent-system to create particles with microvoids for opacity, without the use of polymerization inhibitors or scavengers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polymerization inhibitors or scavengers are used to achieve high opacity values, then opacity performance is improved, but toxicity, cost, and process complexity increase
Solution Approach 1:
The patent removes polymerization inhibitors and scavengers from the process entirely, extracting the harmful elements while maintaining the opacity performance through controlled emulsion polymerization and base swelling of core-sheath-shell particles
Solution Approach 2:
The patent replaces expensive, toxic polymerization inhibitors with a simpler, safer process using common materials like sodium hydroxide for swelling, eliminating the need for costly inhibitors like 4-hydroxy-TEMPO while achieving comparable opacity values
2Reliability
If polymerization inhibitors or scavengers are used to achieve high opacity values, then opacity performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent substitutes expensive polymerization inhibitors with inexpensive, readily available materials such as sodium hydroxide or potassium hydroxide for the swelling step, dramatically reducing material costs while maintaining high opacity performance
Solution Approach 2:
By eliminating the need for costly polymerization inhibitors and scavengers from the process, the patent removes a significant cost component while achieving the same technical results through a simplified process
3Reliability
If polymerization inhibitors or scavengers are used to achieve high opacity values, then opacity performance is improved, but process complexity increases
Solution Approach 1:
The patent removes polymerization inhibitors and scavengers from the process, eliminating the need for complex manual operations such as preparing fresh inhibitor solutions and pouring them into reaction vessels, thereby simplifying the overall process
Solution Approach 2:
The core-sheath-shell particles self-swell through controlled base penetration and neutralization of acid-functional groups, eliminating the need for external inhibitors or scavengers and simplifying the process to basic emulsion polymerization and swelling steps
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 achieves high opacity values comparable to those using inhibitors, but in a safer, more efficient, and cost-effective manner, producing particles suitable for opacifying agents in coatings and other materials.
Implementation Method 1
emulsion polymerizing a core (A) from a core monomer system comprising, as polymerized units, from 5 to 100 percent by weight, based on the weight of the core, of hydrophilic monoethylenically unsaturated monomer containing acid functionality
Implementation Method 2
encapsulating said core (A) with a sheath polymeric layer (B) by emulsion polymerizing a sheath monomer system (E1)
Implementation Method 3
encapsulating said core-sheath particles with a polymeric shell (C) by emulsion polymerizing a shell monomer system (E2)
Implementation Method 4
said sheath permitting penetration of volatile, fixed or permanent bases... said swelling taking place in the presence of a monomer-solvent-system... which, in turn, assists in the penetration of the base through the created polymer layers down to the core
Implementation Method 5
neutralizing and swelling at elevated temperature the resultant core-sheath-shell polymer particles with a volatile, fixed or permanent base
Implementation Method 6
a water soluble polymerization catalyst in a total amount of 0.05 to 0.45% by weight, based on the total amount of monomers in E1 plus E2, is either fed in parallel with the sheath monomer system E1 into the polymerization reactor or is fed into the polymerization reactor before, e.g. right before, emulsion polymerization of E1 in step (ii) starts
Data Source
AI summary
The disclosure relates to processes for preparing an emulsion containing core-sheath-shell polymer particles which, when dried, contain a microvoid which causes opacity in compositions in which they are contained. The particles can serve as binding or opacifying agents in paints, coating, impregnating, and molding compositions primarily, also extended to paper coatings and to some extent in leather, textiles and water based construction materials.