Silane Crosslinking Catalyst for Controlled Plastomer Curing
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Solution Overview
Problem
The handling and processing of EPDM rubber in sealing applications are labor and energy intensive, and there is a need for polyolefin-based rubber materials that can replace EPDM, particularly in automotive and building industries, requiring catalysts that can control crosslinking reaction rates for efficient curing at varying temperatures and pressures.
Innovation Solution
A silane crosslinking catalyst comprising 75 to 85 wt.% of an olefin acrylate interpolymer and 15 to 25 wt.% of a hindered amine light stabilizer (HALS), with optional wax, is used to graft polyolefins with alkoxy silane groups, allowing for controlled crosslinking of ethylene alpha olefin plastomers, promoting Si-O-Si bond formation without tin, carboxylic acid, or sulphonic acid, enabling adaptable curing rates from low at room temperature to high at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional silane crosslinking catalysts are used, then crosslinking can occur, but the reaction rate cannot be controlled to meet varying industrial needs (low curing speed at room temperature for 2-4 days vs. full curing within 20 minutes at 140°C)
Solution Approach 1:
The patent applies parameter changes by formulating a catalyst system with specific compositional parameters (75-85 wt% olefin acrylate interpolymer, 15-25 wt% hindered amine light stabilizer with Mn=1500-4000 g/mol) that enables the crosslinking reaction rate to be controlled across a wide range of temperatures and time conditions, meeting both slow-room-temperature-curing and fast-elevated-temperature-curing requirements
2Reliability
If EPDM rubber is used for sealing applications, then versatility and sealing performance are achieved, but handling and processing become labor and energy intensive with many steps
Solution Approach 1:
The patent extracts the crosslinking function from complex multi-step EPDM processing by using a simplified two-step process: (1) grafting polyolefin with silane groups, and (2) crosslinking with the specific catalyst system, thereby reducing processing complexity while maintaining sealing performance
Solution Approach 2:
The patent creates a composite material system combining polyolefin base polymer with grafted silane groups and the specific catalyst formulation, achieving EPDM-like sealing properties with simplified processing through the synergistic interaction of these components
3Weight of moving object
If polyolefin-based rubbery materials are used to replace EPDM, then weight is reduced and processing is simplified, but control of crosslinking reaction rates for varying industrial needs is insufficient
Solution Approach 1:
The patent achieves adaptability in crosslinking rate control through specific parameter selection in the catalyst formulation (molecular weight range of HALS, composition ratios of olefin acrylate interpolymer and HALS) that enables tuning of reaction kinetics to match different industrial requirements while maintaining the lightweight polyolefin structure
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 catalyst allows for versatile control of crosslinking rates, achieving full curing within 20 minutes at 140°C or 10 minutes at elevated pressure, while maintaining excellent surface finish, shore A hardness, tear strength, and long-term heat aging, even at elevated temperatures, thus replacing EPDM effectively.
Implementation Method 1
a specific crosslinking catalyst... comprising 75 to 85 wt.-% of an olefin acrylate interpolymer and 15 to 25 wt.-% of a hindered amine light stabilizer (HALS)... A silane crosslinking catalyst is a catalyst promoting the hydrolysis of the silicium alkoxy groups to silicium hydroxyl groups
Implementation Method 2
the silane-grafted polymer is subjected to a silanol forming condensation catalyst and then exposed to humidity and/or heat to effect crosslinking. The crosslinking then takes place via formation of backbone-Si-O-Si-backbone' bonds
Implementation Method 3
A silane crosslinking catalyst is a catalyst promoting the hydrolysis of the silicium alkoxy groups to silicium hydroxyl groups
Data Source
AI summary
The present invention relates to silane crosslinking catalyst comprising: - 75 to 85 wt.-% of an olefin acrylate interpolymer and - 15 to 25 wt.-% of a hindered amine light stabilizer (HALS) having a number average molecular weight Mn of 1500 to 4000 g/mol; and - optionally up to 5 wt.-% wax, wherein the silane crosslinking catalyst is free of tin, carboxylic acid(s) and sulphonic acid(s), all weight percentages with respect to the total weight of the silane crosslinking catalyst.