Urethane Adhesive Catalyst Blocking for Flexible Laminate Curing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aliphatic urethane adhesives used in flexible laminate production cure slowly, requiring 5-14 days, which hampers production rates and increases costs, necessitating a method to accelerate the curing process without compromising the adhesive's properties.
Innovation Solution
A method involving a urethane adhesive composition with polyisocyanate, polyfunctional curatives, metallic catalysts, and catalyst blocking agents, such as mercapto compounds or polyphenols, that allows for controlled curing through heat or radiation, enabling faster curing of flexible laminates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If aliphatic urethane adhesives are used for flexible laminate production, then adhesion performance and product resistance are improved, but curing time increases to 5-14 days
Solution Approach 1:
The patent changes the chemical parameters of the adhesive system by introducing a two-component formulation with specific catalysts (tin or bismuth complexes) and blocking agents (mercapto compounds or polyphenols). This parameter change enables controlled trigger curing that reduces cure time from 5-14 days to 1-3 days while maintaining the reliability benefits of aliphatic urethane adhesives.
Solution Approach 2:
The patent uses catalyst blocking agents as intermediaries that temporarily inhibit the curing reaction during application and lamination, then are triggered to release the catalyst activity under specific conditions (heat or moisture). This intermediary mechanism allows the adhesive to remain workable during processing while enabling rapid curing afterward, resolving the contradiction between adhesion performance and curing time.
2Loss of time
If hot rooms are used to store laminated product at 100-110°F, then urethane cure time is reduced to 3-5 days, but production costs and energy consumption increase
Solution Approach 1:
The patent replaces the thermal energy-based curing system (hot rooms at 100-110°F) with a chemical catalyst-based system. The tin or bismuth complex catalysts, when triggered from their blocked state, accelerate the urethane curing reaction at ambient or lower temperatures, eliminating the need for energy-intensive hot room storage while achieving faster cure times.
Solution Approach 2:
The adhesive system is designed to self-cure through the trigger mechanism that activates the catalyst under normal storage conditions (ambient temperature, humidity, or mild heat). This self-service curing eliminates the need for external energy input from hot rooms, reducing energy consumption while maintaining fast cure performance.
3Productivity
If urethane adhesive cures quickly after lamination, then production rate increases, but adhesive may cure too early during application and lamination process
Solution Approach 1:
The patent applies preliminary action by pre-blocking the catalyst before the lamination process. The catalyst is in an inactive blocked state during adhesive application and lamination, providing extended pot life and processing flexibility. Once lamination is complete, the blocking agent is triggered to release the catalyst, initiating rapid curing. This preliminary blocking action resolves the contradiction between fast curing and processing flexibility.
Solution Approach 2:
The patent introduces dynamic control over the curing process through the reversible blocking mechanism. The catalyst activity dynamically transitions from blocked (inactive) during application to unblocked (active) after lamination. This dynamic behavior allows the adhesive to remain workable during processing while enabling rapid curing afterward, achieving both high productivity and ease of operation.
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
This approach significantly reduces the curing time of urethane adhesives to 1 day or less, improving production efficiency and maintaining the adhesive's performance, thus enhancing productivity and cost-effectiveness.
Implementation Method 1
a metallic based catalyst selected from the group consisting of dibutyltindilaurate, stannous acetate, stannic oxide, stannous octoate, dibutyltin dioctoate, tin mercaptides, stannous citrate, stannous oxylate, tetra-phenyl tin, tetra-butyl tin, tri-n-butyl tin acetate, di-alkyl tin dicarboxylates, bismuth tricarboxylates, bismuth nitrate, bismuth sulfide, basic bismuth dicarboxylates and mixtures thereof
Implementation Method 2
at least one catalyst blocking agent comprising a mercapto compound, or a polyphenol with adjacent hydroxyl groups, or both
Data Source
AI summary
A method of producing a flexible laminate and a flexible laminate produced by the method are provided. The method involves laminating flexible substrates with a urethane adhesive and allowing the urethane adhesive to cure. The urethane adhesive comprises at least one polyisocyanate, at least one polyfunctional curative, at least one metal based catalyst and a catalyst blocking agent. The catalyst blocking agent allows for improved control of the curing rate of the urethane adhesive in the flexible laminate. The curing rate of the urethane adhesive can be controlled with heat or actinic radiation or both. The method allows for faster and more economical production of flexible laminates.