Soap-Free Polychloroprene Latex via Surfactant Concentration Control
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Solution Overview
Problem
Traditional polychloroprene latexes produced via emulsion polymerization require large amounts of emulsifiers, leading to inadequate adhesion and water resistance, and existing soap-free polymerization methods for chloroprene have not been effectively disclosed, often resulting in deposit formation and complex multi-step processes.
Innovation Solution
A method of producing polychloroprene latex via soap-free polymerization in an aqueous medium with an anionic surfactant at concentrations below its critical micelle concentration (CMC), achieving improved adhesion properties and reduced deposit formation without the need for surface-active hydrophilic groups or multiple production steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional emulsion polymerization is used to produce polychloroprene latex, then the polymerization process can proceed, but a great amount of emulsifier is required which deteriorates adhesion properties and water resistance
Solution Approach 1:
The patent changes the key parameter of emulsifier concentration from traditional high levels (required for emulsion polymerization) to extremely low levels (0.001-0.5 wt%, below CMC). This parameter change enables the polymerization to proceed via a different mechanism (soap-free polymerization) that produces large-sized particles (0.1-10 μm) with excellent adhesion properties and water resistance, eliminating the trade-off between process feasibility and product performance
Solution Approach 2:
The patent inverts the traditional approach by using emulsifier concentrations below the critical micelle concentration (CMC) rather than above it. This inversion leads to a completely different polymerization mechanism where polymer particles form without micelle stabilization, resulting in superior adhesion properties while maintaining process feasibility through careful control of other parameters like initiator concentration and polymerization temperature
2Reliability
If soap-free polymerization is used to reduce emulsifier content, then adhesion properties improve, but a great amount of deposits are formed
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: emulsifier concentration (0.001-0.5 wt%), initiator concentration (0.1-5 wt%), and polymerization temperature (50-80°C). This coordinated parameter optimization enables soap-free polymerization to proceed efficiently with minimal deposit formation while achieving excellent adhesion properties, resolving the contradiction between improved adhesion and reduced substance loss
3Quantity of substance
If existing soap-free polymerization methods are applied to chloroprene, then emulsifier content is reduced, but the process becomes complex with multiple steps and deposit formation increases
Solution Approach 1:
The patent establishes an optimized parameter range for emulsifier (0.001-0.5 wt%), initiator (0.1-5 wt%), and temperature (50-80°C) that enables single-step soap-free polymerization of chloroprene. This parameter optimization simplifies the production process compared to existing multi-step methods while achieving low emulsifier content and minimal deposits, resolving the contradiction between reduced substance quantity and process complexity
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
This method results in polychloroprene latex with enhanced initial adhesive strength and a wide range of particle sizes, suitable for various materials, while minimizing surfactant usage and simplifying the production process, thus overcoming the limitations of traditional methods.
Implementation Method 1
polymerizing chloroprene or a mixture of chloroprene and a monomer copolymerizable with chloroprene in the presence of an anionic surfactant in an aqueous medium, to which the surfactant being added at a concentration of 0.00001 wt part or more based on 100 wt parts of the aqueous medium and less than its critical micelle concentration (CMC)
Implementation Method 2
polymerized by addition of a radical initiator such as potassium persulfate
Data Source
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AI summary
Provided is a polychloroprene latex extremely superior in adhesion properties. According to the present invention, chloroprene or a mixture of chloroprene and a monomer copolymerizable with chloroprene is polymerized in the presence of a surfactant in an aqueous medium, in which the surfactant's concentration is lower than its critical micelle concentration (CMC) to obtain a polychloroprene latex. The polychloroprene latex produced according to the present invention is extremely superior in adhesion properties and others and give a smaller amount of deposits during production.