Solketal (Meth)acrylate Emulsion Polymerization at Neutral pH
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Solution Overview
Problem
The use of acidic reacting polymerization initiators, such as persulfates, in the preparation of aqueous polymer latex containing solketal (meth)acrylate leads to an acidic pH below 6, which can cause hydrolysis and coagulation issues during radical emulsion polymerization.
Innovation Solution
Maintaining an essentially neutral pH range of 6 to 8 in the aqueous polymerization medium by the presence of a basic compound during the polymerization process, using basic compounds like sodium hydroxide or sodium bicarbonate to neutralize the acidic initiator, thereby preventing hydrolysis and coagulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If acidic reacting polymerization initiators (such as persulfates) are used in the preparation of aqueous polymer latex containing solketal (meth)acrylate, then the polymerization reaction can be initiated, but the pH drops below 6 causing hydrolysis and coagulation issues
Solution Approach 1:
A base compound is introduced as an intermediary substance that reacts with the acidic initiator to neutralize the acid, preventing the harmful hydrolysis and coagulation effects while allowing the polymerization reaction to proceed. The base compound acts as a mediator between the acidic initiator and the monomer system.
Solution Approach 2:
The pH parameter of the reaction medium is changed from acidic (below 6) to neutral or slightly basic (pH 6-8) by adding a base compound. This parameter change eliminates the harmful effects of acid-catalyzed hydrolysis and coagulation while maintaining polymerization activity.
2Productivity
If acidic pH conditions are maintained during polymerization, then the polymerization reaction proceeds, but monomer loss increases due to hydrolysis
Solution Approach 1:
The acidic properties of the initiator, which originally cause harmful hydrolysis, are converted into a beneficial neutralization process by adding a base compound. The base compound reacts with the acid to form salt and water, eliminating the harmful effect while allowing the polymerization to proceed efficiently.
Solution Approach 2:
The pH parameter is changed from acidic to neutral/basic, which prevents monomer hydrolysis and reduces monomer loss while maintaining adequate polymerization reaction rate.
3Productivity
If acidic pH conditions are maintained during polymerization, then the polymerization reaction proceeds, but polymer latex integrity deteriorates due to coagulation
Solution Approach 1:
The base compound serves as an intermediary that neutralizes the acidic initiator, preventing acid-induced coagulation and maintaining the stability and integrity of the polymer latex structure throughout the polymerization process.
Solution Approach 2:
The pH parameter is adjusted to neutral or basic levels, which prevents coagulation and maintains the structural integrity and stability of the polymer latex.
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 ensures stable polymerization with minimal monomer loss and maintains the integrity of the polymer latex, achieving a stable dispersion without coagulation.
Implementation Method 1
Maintaining an essentially neutral pH range of 6 to 8 in the aqueous polymerization medium by the presence of a basic compound during the polymerization process, using basic compounds like sodium hydroxide or sodium bicarbonate to neutralize the acidic initiator
Implementation Method 2
The free-radically initiated aqueous emulsion polymerization is triggered by means of a free-radical polymerization initiator (free-radical initiator). These are in principle peroxides, persulfates, azo compounds and redox initiator systems.
Implementation Method 3
a process for preparing an aqueous polymer latex by polymerizing, optionally in the presence of a seed latex, a monomer composition containing solketal (meth)acrylate by radical emulsion polymerization in an aqueous polymerization medium
Data Source
AI summary
A process for preparing an aqueous polymer latex by polymerizing, optionally in the presence of a seed latex, a monomer composition containing solketal (meth)acrylate by radical emulsion polymerization in an aqueous polymerization medium in the presence of an acidic reacting radical polymerization initiator, wherein the monomer composition comprises a) 0.1 to 100% by weight of solketal (meth)acrylate, b) 0 to 99.9% by weight of one or more further ethylenically unsaturated monomers, characterized in that an essentially neutral pH in the range of from 6 to 8 is maintained in the aqueous polymerization medium during the radical emulsion polymerization reaction by the presence of a basic compound.