Scorch Resistant Polyethylene Composition Using Dual Peroxide System
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polyethylene compositions used in multilayer articles like power cables face challenges in maintaining high cross-linking efficiency while avoiding premature scorch formation during extrusion, which leads to inhomogeneity and surface unevenness.
Innovation Solution
A polyethylene composition comprising unsaturated polyethylene with a specific mixture of peroxides, including 1,3-bis(tert-butylperoxyisopropyl)-benzene and dicumylperoxide, where the first peroxide has a 10-hour-half-life-temperature 1 to 10 degrees higher than the second peroxide, is used to control the decomposition rate and balance cross-linking efficiency and scorch suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single peroxide cross-linking agent is used to achieve high cross-linking efficiency, then cross-linking speed is improved, but premature decomposition occurs during extrusion causing scorch formation and inhomogeneity
Solution Approach 1:
The single peroxide cross-linking agent is segmented into a mixture of two different peroxides with different decomposition characteristics. This allows the cross-linking process to be divided into two stages: one peroxide provides initial cross-linking activity while the other provides sustained cross-linking, preventing premature decomposition and scorch formation during extrusion while maintaining high cross-linking efficiency
Solution Approach 2:
The decomposition temperature parameter of the cross-linking agent mixture is changed by combining two peroxides with different half-life temperatures. This parameter modification allows the cross-linking reaction to occur at optimized temperatures during extrusion, preventing premature decomposition and scorch while ensuring complete cross-linking
2Manufacturing precision
If peroxide decomposition is suppressed during extrusion to avoid scorch, then scorch formation is reduced, but cross-linking efficiency decreases
Solution Approach 1:
The useful cross-linking action is made continuous through the use of two peroxides with different decomposition profiles. One peroxide decomposes first to initiate cross-linking, while the second peroxide continues the cross-linking process, ensuring continuous and complete cross-linking without interruption or premature termination
Solution Approach 2:
A composite cross-linking system is created by combining two different peroxide compounds. This composite approach leverages the complementary decomposition characteristics of both peroxides to achieve both scorch resistance during extrusion and high cross-linking efficiency in the final product
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 composition achieves improved resistance to scorch formation and enhanced cross-linking, resulting in better thermal and mechanical stress resistance with reduced environmental stress and exudation issues.
Implementation Method 1
a first peroxide which is 1, 3 1,4-bis (tert-butylperoxyisopropyl)-benzene and a second peroxide which is dicumylperoxide, wherein the first peroxide has a 10-hour-half-life-temperature which is 1 to 10 degrees higher than that of the second peroxide
Implementation Method 2
The cross-linking of the used polyethylene composition is of special interest since deformation resistance at elevated temperature of the cable can be improved
Data Source
Figure 1~2
AI summary
The present invention relates to a cross-linkable polyethylene composition, comprising (i) an unsaturated polyethylene having a total amount of carbon-carbon double bonds/1000 carbon atoms of at least 0.1, and (ii) a cross-linking agent mixture comprising a first and a second peroxide, wherein the first peroxide has a 10-hour-half-life-temperature which is 1 to 10 degrees higher than that of the second peroxide, and wherein said first peroxide is present in an amount of at least 8 wt% based on the total amount of the first and second peroxide of the cross-linking agent mixture.