Tin-Free Silicone Rubber Catalyst Mixture for Adhesion
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Solution Overview
Problem
Existing silicone rubber compositions optimized with organotin catalysts cannot maintain desired properties when switched to tin-free catalysts, resulting in poor adhesion and storage stability, especially with acetate crosslinkers.
Innovation Solution
A catalyst composition comprising a mixture of metal salts of carboxylic acids, specifically zinc, bismuth, calcium, potassium, lithium, and magnesium salts, is used to crosslink silicone rubber compositions, providing improved adhesion and storage stability without the need for additional co-catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If organotin catalysts are used for crosslinking silicone rubber compounds, then the desired adhesion and storage stability are achieved, but toxicological restrictions are imposed on their use
Solution Approach 1:
The patent replaces persistent toxic organotin catalysts with biodegradable metal salt catalysts (zinc, calcium, magnesium, bismuth, potassium, or lithium salts of carboxylic acids). These alternative catalysts achieve the required catalytic function for crosslinking while being environmentally friendly and free from toxicological restrictions, allowing the product to meet both performance and safety requirements
Solution Approach 2:
The patent changes the chemical composition parameters of the catalyst system by transitioning from organotin compounds to inorganic metal salts with specific properties (solubility in silicone oil, catalytic activity, non-toxicity). This parameter change enables the removal of toxic substances while maintaining the essential function of controlling polymerization rate and degree of crosslinking
2Object-affected harmful factors
If tin-free catalysts are used to replace organotin catalysts, then toxicological restrictions are avoided, but adhesion and storage stability deteriorate
Solution Approach 1:
The patent optimizes specific parameters of the metal salt catalysts including their solubility in silicone oil, catalytic activity, and compatibility with crosslinking agents. By carefully selecting metal salts with appropriate solubility characteristics and catalytic strengths, the patent achieves both tin-free formulation and maintained adhesion/storage stability properties
Solution Approach 2:
The patent employs composite catalyst systems combining multiple metal salts (zinc, calcium, magnesium, bismuth, potassium, or lithium salts of carboxylic acids) to achieve synergistic effects. This composite approach allows the catalyst system to provide both the necessary catalytic function and the improved stability properties that single catalysts cannot achieve alone
3Device complexity
If a single catalyst compound is used, then the catalyst system is simple, but the curing properties and adhesion are insufficient
Solution Approach 1:
The patent utilizes composite catalyst systems combining multiple metal salt compounds that work synergistically. The combination of different metal salts (zinc, calcium, magnesium, bismuth, potassium, or lithium salts of carboxylic acids) provides enhanced catalytic activity, improved adhesion properties, and better storage stability compared to single catalyst compounds, while maintaining reasonable system complexity
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 mixture ensures excellent adhesion to various materials and maintains storage stability, producing transparent, clear silicone rubber products with desired curing properties, such as skin formation time, tack-free time, and hardness.
Implementation Method 1
Polymerization generally occurs through the condensation of SiOH groups with suitable hydrolyzable SiX groups of the crosslinkers
Implementation Method 2
a catalyst for the crosslinking of silicone rubber compounds... wherein the composition comprises this catalyst... a use of the catalyst for crosslinking a silicone rubber compound
Data Source
AI summary
The present invention relates to a catalyst for cross-linking silicone rubber compositions. In particular, the present invention provides a composition for producing a silicone rubber composition, the composition comprising a catalyst which has at least two compounds that are different from each other and are selected independently from one another from metal salts of carboxylic acids. The present invention further provides a use of the catalyst according to the invention for cross-linking a silicone rubber composition, and a use of the composition according to the invention for producing a silicone rubber composition, in particular for use as a sealant, an adhesive or a coating agent.