Reactive Polyolefin Composition for Peroxide-Free Cable Crosslinking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polyolefin compositions used in cable applications face challenges with peroxide crosslinking, leading to undesirable by-products, increased production costs, and limited extruder output due to peroxide degradation, which affect electrical properties and mechanical performance.
Innovation Solution
A polyolefin composition comprising LDPE with epoxy groups and polypropylene with carboxylic acid groups or their precursors, allowing in situ crosslinking without peroxide, leveraging the reaction between epoxy and carboxylic acid groups to form crosslinks at typical formulation temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If peroxide is used as a crosslinking agent, then crosslinking density and mechanical strength are improved, but harmful volatile by-products are generated that negatively affect electrical properties
Solution Approach 1:
The patent changes the chemical parameters of the crosslinking system by replacing peroxide with silane-based crosslinking agents and catalysts. This substitution fundamentally alters the crosslinking chemistry to eliminate volatile by-products while maintaining crosslinking density and mechanical strength through siloxane bond formation.
Solution Approach 2:
The patent converts the typically harmful role of moisture (which can interfere with crosslinking) into a beneficial component by utilizing water-reactive silane groups that require moisture to initiate crosslinking. This transforms a potential contaminant into the activation mechanism for crosslinking, eliminating the need for peroxide and its harmful decomposition products.
2Strength
If peroxide is added in a separate processing step, then crosslinking is achieved, but production time and process complexity increase
Solution Approach 1:
The patent merges the crosslinking agent and catalyst directly into the polymer compound during the extrusion process. This integration eliminates the need for separate peroxide addition steps and subsequent degassing operations, reducing production time and simplifying the manufacturing process while achieving effective crosslinking.
Solution Approach 2:
The patent performs preliminary incorporation of silane crosslinking agents and catalysts into the polymer during compounding, so that crosslinking is already prepared and activated during extrusion. This preliminary action eliminates the need for post-extrusion peroxide addition and allows immediate crosslinking without additional processing steps.
3Reliability
If peroxide degradation temperature is limited to 140°C, then peroxide stability is maintained, but extruder output and production speed are reduced
Solution Approach 1:
The patent changes the thermal parameters of the crosslinking system by using silane-based crosslinking agents that are stable at higher extrusion temperatures (typically 180-220°C). This allows the extruder to operate at optimal temperatures for both polymer processing and crosslinking activation, significantly increasing extruder output and production speed compared to peroxide-limited processes.
4Loss of time
If crosslinking is performed without peroxide, then production time and costs are reduced, but crosslinking density and mechanical properties may be compromised
Solution Approach 1:
The patent utilizes moisture, which is typically considered a contaminant in polymer processing, as the activation mechanism for silane crosslinking. By incorporating water-reactive silane groups and catalysts into the polymer compound, the patent converts moisture into the trigger for crosslinking, enabling rapid crosslinking during extrusion without peroxide and maintaining mechanical properties.
Solution Approach 2:
The patent changes the chemical mechanism of crosslinking from peroxide-based free radical crosslinking to silane-based condensation crosslinking. This parameter change enables crosslinking to occur at lower temperatures and shorter times while achieving comparable or superior mechanical properties through the formation of a three-dimensional siloxane network.
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 crosslinking without peroxide, reducing production time and costs, improving mechanical properties, and maintaining electrical performance, while eliminating the need for degassing steps and peroxide-related issues.
Implementation Method 1
the reaction between epoxy and carboxylic acid groups to form crosslinks
Data Source
Figure 1
Figure 2
AI summary
The invention provides a polyolefin composition comprising (i) a polyolefin (A) comprising epoxy groups; and (ii) a polyolefin (B) comprising carboxylic acid groups and/or precursors thereof, with the proviso that at least one of (A) and (B) is polyethylene. Preferably one of (A) and (B) is a low density polyethylene (LDPE) and the other is a polypropylene.