Sulfur-Modified Chloroprene Elastomer Viscosity Stability
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Solution Overview
Problem
Conventional methods fail to simultaneously improve viscosity stability during storage and scorching resistance during processing of sulfur-modified chloroprene elastomer compositions.
Innovation Solution
Specifying the amount of organic acids, ash content, and mass ratio thereof, along with blending a particular amount of a thiuram compound, such as tetraethylthiuram disulfide, in the sulfur-modified chloroprene elastomer composition to enhance both viscosity stability and scorching resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If sulfur-modified chloroprene elastomer composition is used to improve impact resilience and tear strength, then mechanical properties are improved, but viscosity stability during storage deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting the pH of the latex before copolymerization to a specific range of 4.8-6.0, and by controlling the sulfur content at 0.5-2.0 mass% and organic acid content at 1-10 mass%. These parameter optimizations resolve the contradiction by maintaining viscosity stability while preserving the mechanical properties of sulfur-modified chloroprene elastomer.
Solution Approach 2:
The patent creates a composite material system by blending sulfur-modified chloroprene elastomer with specific organic acids (acetic acid, propionic acid, butyric acid) and their corresponding salts. This composite approach allows the system to maintain both improved mechanical properties from sulfur modification and enhanced viscosity stability from the organic acid buffer system.
2Strength
If sulfur-modified chloroprene elastomer composition is used to improve mechanical properties, then impact resilience and tear strength are improved, but scorching resistance during processing deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling the organic acid content at 1-10 mass% and ash content at 0.03-0.2 mass%, with specific attention to the mass ratio of organic acid to ash (50-500). These parameter optimizations prevent premature vulcanization (scorching) during processing while maintaining the mechanical properties of the sulfur-modified elastomer.
Solution Approach 2:
The patent uses organic acids and their salts as intermediary substances that mediate between the sulfur modification (which improves mechanics) and processing stability (which requires scorch resistance). The organic acid buffer system acts as a mediator to control the reactivity of sulfur during processing, preventing scorching while allowing proper vulcanization later.
3Stability of the object's composition
If conventional methods adjust pH to improve viscosity stability, then viscosity stability during storage is improved, but scorching resistance during processing is not improved
Solution Approach 1:
The patent applies universality by using organic acids and their salts that simultaneously perform multiple functions: (1) buffering pH to improve viscosity stability during storage, and (2) controlling sulfur reactivity to improve scorching resistance during processing. This multi-functional approach resolves the contradiction by making a single additive system responsible for both stability aspects.
Solution Approach 2:
The patent creates a composite chemical system combining organic acids (acetic acid, propionic acid, butyric acid) with their corresponding salts in specific ratios. This composite approach allows the system to provide both pH buffering for viscosity stability and controlled sulfur reactivity for scorch resistance, achieving both benefits simultaneously.
4Reliability
If conventional methods blend thiuram compound to improve scorching resistance, then scorching resistance is improved, but viscosity stability during storage is not improved
Solution Approach 1:
The patent applies universality by using organic acid-thiuram compound combinations where the organic acid component provides pH buffering for viscosity stability while the thiuram compound provides scorching resistance. The synergistic interaction between these components allows both functions to be achieved simultaneously, with the organic acid stabilizing the system during storage and the thiuram compound protecting during high-temperature processing.
Data Source
AI summary
Provided is a sulfur-modified chloroprene elastomer composition superior both in viscosity stability during storage and scorching resistance during processing and a blend and vulcanized article thereof. A sulfur-modified chloroprene elastomer composition, containing a thiuram compound in an amount of 1 to 2.5 mass % and having an organic acid content, as determined in accordance with JIS K6237, of 1.5 to 15 mass %, an ash content, as determined in accordance with JIS K6228, of 0.03 to 0.2 mass %, and a mass ratio of the organic acid content to the ash content (organic acid content/ash content) of 50 to 500, as they are so regulated by modification of the blending amount of the emulsifier.