Chlorinated Polymer Mixture Storage Stability
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Solution Overview
Problem
Chlorinated polymer mixtures, particularly those based on sulfur-free polychloroprene, face storage stability issues when containing N,N'-ethylenethiourea as a crosslinking agent, leading to decreased mechanical properties and increased surface defects in extruded cables and lines with extended storage times.
Innovation Solution
A polymer mixture comprising sulfur-free polychloroprene, mineral fillers, plasticizers, anti-aging agents, and a crosslinking system without N,N'-ethylenethiourea, using methyl-2-mercaptobenzimidazole, trimethoxyvinylsilane, 3-methyl-2-thiazolidinethione, and 2-mercaptobenzothiazole disulfide, which maintains mechanical properties and storage stability for at least 28 days, allowing for improved processability and surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If N,N'-ethylenethiourea is used as a crosslinking agent in chlorinated polymer mixtures, then crosslinking efficiency is improved, but storage stability deteriorates with extended storage times
Solution Approach 1:
The patent changes the chemical composition parameters of the crosslinking system by replacing N,N'-ethylenethiourea with a combination of methyl-2-mercaptobenzimidazole, trimethoxyvinylsilane, 3-methyl-2-thiazolidinethione, and 2-mercaptobenzothiazole disulfide. This parameter change maintains crosslinking efficiency while eliminating the storage stability deterioration problem associated with ethylenethiourea.
2Loss of time
If extended storage time is allowed for polymer mixtures containing ethylenethiourea, then production flexibility is improved, but mechanical properties deteriorate
Solution Approach 1:
The patent prepares the polymer mixture in advance with the new crosslinking system components (methyl-2-mercaptobenzimidazole, trimethoxyvinylsilane, 3-methyl-2-thiazolidinethione, and 2-mercaptobenzothiazole disulfide) that are designed to remain stable during extended storage. The crosslinking reaction is activated only when needed through heat or radiation, allowing preliminary preparation and storage without property deterioration.
3Loss of time
If extended storage is permitted for the polymer mixture, then process scheduling flexibility is improved, but surface quality deteriorates due to increased surface defects
Solution Approach 1:
The patent changes the chemical parameters of the crosslinking system to use alternatives that do not undergo premature crosslinking reactions during storage. The new system (methyl-2-mercaptobenzimidazole combined with trimethoxymethylsilane, 3-methyl-2-thiazolidinethione, and 2-mercaptobenzothiazole disulfide) maintains stability during storage and only activates upon controlled heat or radiation application, preventing surface defects even after extended storage periods.
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 polymer mixture exhibits enhanced storage stability, mechanical properties, and processability, with improved surface quality and extended processing times, achieving comparable mechanical strengths to mixtures with ethylenethiourea without the defects associated with longer storage.
Implementation Method 1
a crosslinking system which has or consists of methyl-2-mercaptobenzimidazole, silane, 3-methyl-2-thiazolidinethione, and 2-mercaptobenzothiazole disulfide
Implementation Method 2
The crosslinking is preferably carried out by heating, for example to a temperature of at least 150 °C, in particular to 180 °C to 220 °C
Implementation Method 3
this crosslinkable polymer mixture is plasticized in an extruder and extruded into a layer of a cable or a line
Data Source
Figure 1~2
AI summary
Cross-linkable polymer mixture comprises 100 parts per hundred rubber (phr) polychloroprene. The polychloroprene comprises 0-40 phr natural rubber (NR) and/or styrene-butadiene rubber (SBR), 20-100 phr mineral filler, colorant, plasticizer, anti-aging agent, 3-16 phr processing aid, 0.5-4 phr coupling agent, and cross-linking system comprising 0.3-2 phr methyl-2-mercaptobenzimidazole, 0.5-4 phr silane, 0.5-4 phr 3-methyl-2-thiazolidinethione and 0.3-2 phr 2-mercaptobenzothiazole disulfide, and 3-6 phr stabilizer, and 3-6 phr zinc oxide as catalyst. Independent claims are included for the following: (1) cable or line with sheathing made of a polymer mixture; and (2) method for manufacturing cables or lines, involves extruding the above-mentioned cross-linkable polymer mixture with subsequent cross-linking.