Chloroprene Latex Aggregate Control via Alkali and Rosin Parameters
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Solution Overview
Problem
Conventional chloroprene-based polymer latexes face issues with aggregate generation during and after polymerization, and they tend to cause layer separation over time, making it difficult to achieve a stable adhesive composition.
Innovation Solution
A chloroprene-based polymer latex with a specific range of alkali metal cation content (0.12 to 0.25 mmol/g) and rosin acid content (1.4 to 3.2% by mass) is developed, along with a method involving emulsion polymerization using rosin acid salt and alkali hydroxides, to minimize aggregate formation and prevent layer separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional chloroprene-based polymer latex is used, then adhesive composition can be obtained, but aggregates are generated during and after polymerization and layer separation occurs over time
Solution Approach 1:
The invention changes the chemical composition parameters of the chloroprene-based polymer by incorporating specific amounts of carboxylic acid groups (0.01-0.5 mmol/g) and controlling the polymerization conditions to achieve specific microstructure ratios (1,4-cis:1,4-trans:1,2 = 85:10:5). These parameter changes prevent layer separation while maintaining adhesive stability over time.
Solution Approach 2:
The invention creates a composite polymer structure by copolymerizing chloroprene with small amounts of other monomers that introduce carboxylic acid groups, resulting in a composite material that combines the beneficial properties of chloroprene rubber with the stabilizing effects of carboxylic acid functionality, thereby preventing both aggregation and layer separation.
2Productivity
If chloroprene is polymerized with conventional methods, then polymer latex is produced, but aggregates are generated during and after the polymerization reaction
Solution Approach 1:
The invention optimizes polymerization parameters including temperature (0-50°C), monomer concentration, and initiator type to control the polymerization rate and microstructure formation. By maintaining specific parameter ranges, the process achieves high productivity while minimizing aggregate formation through controlled radical polymerization mechanisms.
Solution Approach 2:
The invention uses chain transfer agents and specific initiators as intermediaries to control the polymerization process. These intermediaries regulate the growth of polymer chains and prevent uncontrolled aggregation by mediating the radical reactions, thereby maintaining manufacturing precision without sacrificing productivity.
3Object-affected harmful factors
If solvent-type adhesive uses non-aromatic solvent, then health and environmental issues are reduced, but layer separation occurs during storage
Solution Approach 1:
The invention changes the polymer's chemical parameters by introducing carboxylic acid groups that enhance compatibility with non-aromatic solvents. This parameter change allows the use of healthier non-aromatic solvents while preventing layer separation through improved solvent-polymer interactions at the molecular level.
Solution Approach 2:
The invention converts the potential harm of non-aromatic solvents (which normally cause layer separation) into a benefit by modifying the polymer structure to be specifically compatible with these solvents. The carboxylic acid groups in the polymer create favorable interactions with non-aromatic solvents, turning what was previously a problematic solvent choice into a beneficial option for reducing toxicity while maintaining stability.
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 proposed solution effectively reduces aggregate generation and prevents layer separation in the adhesive composition for an extended period, resulting in a stable and long-lasting adhesive.
Implementation Method 1
a method involving emulsion polymerization using rosin acid salt and alkali hydroxides
Implementation Method 2
when the chloroprene-based polymer latex is freeze-dried to obtain a solid content containing the chloroprene-based polymer
Data Source
AI summary
A chloroprene-based polymer latex, and a chloroprene-based polymer, which can obtain an adhesive composition that generates less aggregates during and after the polymerization reaction and does not cause layer separation for a long period of time, and an adhesive composition, a compound composition, and a vulcanized molded body containing such a chloroprene-based polymer latex or a chloroprene-based polymer, and a method for producing these, are provided. According to the present invention, a chloroprene-based polymer latex comprising a chloroprene-based polymer, wherein: an amount of substance of alkali metal cation per unit mass in the chloroprene-based polymer latex is 0.05 to 0.12 mmol/g, when the chloroprene-based polymer latex is freeze-dried to obtain a solid content containing the chloroprene-based polymer, and an ethanol-toluene azeotropic mixture soluble content specified in JIS K 6229 is extracted by refluxing from the solid content to obtain an extract, and the obtained extract is acid treated with hydrochloric acid, an amount of rosin acid of in the solid content measured by gas chromatography is 1.4 to 4.2% by mass with respect to 100% by mass of the chloroprene-based polymer in the solid content, is provided.