Nitrile Rubber Coagulation Using Alkali Metal Salts
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Solution Overview
Problem
Existing nitrile rubber production methods face challenges in achieving low water swelling, rapid vulcanization, and high storage stability while minimizing the use of precipitants and maintaining low impurity levels in the final product.
Innovation Solution
A nitrile rubber with a specific ion index of 18 to 29 ppm x mol/g, produced through emulsion polymerization using an alkali metal salt as a precipitant, gelatin as a co-precipitant, and controlled temperature conditions, results in excellent storage stability, high vulcanization rate, and low water swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polyvalent metal ions are used for coagulation, then coagulation efficiency is improved, but emulsifier inclusion and water swelling increase
Solution Approach 1:
The patent changes the ionic parameter from polyvalent metal ions to monovalent alkali metal ions, which fundamentally alters the coagulation mechanism. This parameter change reduces emulsifier inclusion and subsequent water swelling while maintaining acceptable coagulation efficiency through optimized process conditions
Solution Approach 2:
The patent introduces organic acids as intermediaries to mediate the coagulation process. These acids provide controlled pH reduction and cation release, enabling efficient coagulation without the harmful effects of direct polyvalent metal ion addition, thus reducing water swelling
2Ease of manufacture
If emulsifier is retained in rubber during coagulation, then process economics are improved, but water swelling increases
Solution Approach 1:
The patent changes the coagulation chemistry from acid-based to alkali metal salt-based, which fundamentally alters how emulsifiers interact with the coagulum. This parameter change allows emulsifiers to remain in the rubber without causing excessive water swelling, thus maintaining process economics while reducing the harmful effect
3Object-affected harmful factors
If washing is performed to remove electrolytes, then water swelling is reduced, but manufacturing complexity and time increase
Solution Approach 1:
The patent extracts the harmful polyvalent metal ions and emulsifier inclusion from the system by using monovalent alkali metal ions for coagulation. This extraction eliminates the need for extensive washing operations, reducing both manufacturing complexity and time while maintaining low water swelling
Solution Approach 2:
The coagulation process itself is designed to produce a coagulum with inherently low emulsifier inclusion and electrolyte content. The process serves its own purification function, eliminating the need for separate intensive washing steps and reducing manufacturing 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
The process yields nitrile rubbers with improved storage stability, rapid vulcanization, and reduced water swelling, while minimizing impurities and precipitant usage, enhancing the mechanical properties and reproducibility of vulcanizable mixtures.
Implementation Method 1
The latex obtained in the emulsion polymerization is subjected to coagulation
Implementation Method 2
gelatin is used as a co-precipitant for latex coagulation
Data Source
AI summary
An improved polymerization and processing method allows the production of special nitrile rubbers which are characterized by a specific cation content which leads to an excellent storage stability and particularly good vulcanization rate and moreover results in vulcanized materials that have advantageous properties, especially with regard to the contact with water or water-containing media of molded parts based on said vulcanized materials.