Nitrile Rubber Coagulation via pH and Ion Control
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Solution Overview
Problem
Existing processes for producing nitrile rubbers face challenges in achieving rapid vulcanization and high modulus properties while minimizing the amount of electrolyte used in coagulation, which affects the quality and processing efficiency of the final product.
Innovation Solution
The process involves coagulating nitrile rubber latices using magnesium salts with optional calcium replacement, employing gelatin as a coprecipitant, and controlling the temperature to achieve specific calcium and magnesium ion concentrations, resulting in nitrile rubbers with improved storage stability and vulcanization rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If polyvalent metal ions (e.g., calcium chloride, magnesium chloride) are used for coagulation, then the amount of electrolyte required is reduced, but emulsifier inclusion in the product increases and washing becomes more difficult
Solution Approach 1:
The patent changes the chemical parameter of the coagulating agent from polyvalent metal ions to monovalent metal ions (sodium, potassium), and combines it with specific pH control (pH 2-4) to achieve effective coagulation while minimizing emulsifier inclusion and facilitating easier washing
2Ease of manufacture
If monovalent metal ions (e.g., sodium chloride) are used for coagulation, then washing becomes easier and emulsifier inclusion is reduced, but significantly larger amounts of electrolyte are required
Solution Approach 1:
The patent modifies the coagulation process by using monovalent metal ions in combination with controlled pH (pH 2-4), which enhances the coagulation efficiency and reduces the amount of electrolyte needed while maintaining easy washing characteristics
3Ease of manufacture
If conventional coagulation processes are used, then production is simpler, but vulcanization rate and modulus properties cannot be optimized
Solution Approach 1:
The patent optimizes specific parameters of the coagulation process (pH 2-4, temperature 0-50°C, use of monovalent metal ions) to control the microstructure and composition of the coagulated rubber, which subsequently influences vulcanization rate and modulus properties, achieving both process simplicity and improved vulcanization performance
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 approach yields nitrile rubbers with high storage stability, reduced differences between initial and full vulcanization rates, and excellent mechanical properties, including high modulus values, while minimizing residual emulsifiers and electrolytes.
Implementation Method 1
the coagulation of the latex is carried out using at least one magnesium salt as precipitant, with optionally up to 40% by weight of the magnesium salt being replaced by a calcium salt
Implementation Method 2
the coagulation of the latex is carried out using at least one magnesium salt as precipitant
Implementation Method 3
employing gelatin as a coprecipitant
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.