Debondable Lamination Adhesive for Retort Packaging
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Solution Overview
Problem
Existing two-component adhesive compositions for laminating applications are cumbersome to use, require separate storage and mixing, leading to potential errors and increased costs, and are not suitable for delamination and retort processing, while one-component compositions are not commonly used for laminating due to their limitations.
Innovation Solution
A one-component adhesive composition with a linear backbone structure and isocyanate moieties, derived from diol and polyisocyanate components, is developed, which can be applied directly to substrates without mixing, facilitating delamination and retort processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If two-component adhesive compositions are used for laminating, then bond strength is improved, but device complexity and ease of operation deteriorate due to separate storage and mixing requirements
Solution Approach 1:
The patent combines two separate adhesive components (isocyanate component and polyol component) into a single one-component adhesive composition containing latent isocyanate groups. This merging eliminates the need for separate storage containers and mixing equipment, reducing device complexity while maintaining the bonding functionality through thermal activation of the latent isocyanate groups.
Solution Approach 2:
The patent incorporates latent isocyanate groups into the adhesive composition during manufacturing, preparing the adhesive in advance with dormant reactive groups. These latent isocyanate groups remain inactive during storage and application, then activate upon heating during the lamination process, eliminating the need for on-site mixing while preserving the two-component reaction mechanism's bond strength.
2Strength
If two-component adhesive compositions are used, then bond strength is improved, but loss of time increases due to mixing requirements
Solution Approach 1:
The adhesive composition is pre-prepared with latent isocyanate groups incorporated during manufacturing. This preliminary action eliminates the time-consuming mixing step that would otherwise be required on-site, while the latent groups ensure that the bonding reaction only occurs when thermally activated during the lamination process, maintaining bond strength without the time loss.
3Strength
If conventional adhesives are used for laminating, then bond strength is achieved, but adaptability deteriorates for delamination and retort processing applications
Solution Approach 1:
The patent changes the chemical parameter of the adhesive by incorporating latent isocyanate groups that remain dormant at room temperature but activate upon heating. This parameter change enables the adhesive to maintain bond strength during lamination while allowing for subsequent delamination through alkaline treatment and retort processing, as the latent isocyanate groups do not form permanent crosslinks that would prevent these processes.
4Ease of operation
If one-component adhesive compositions are used, then ease of operation is improved, but bond strength deteriorates compared to two-component systems
Solution Approach 1:
The patent changes the reactivity parameter of the isocyanate groups by converting them to latent form. This allows the one-component adhesive to be easily applied without mixing while maintaining the potential for strong bonding, as the latent isocyanate groups activate upon heating during the lamination process to form urethane linkages with the polyol, achieving bond strength comparable to two-component systems.
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 one-component adhesive composition enables efficient delamination and deinking, reduces waste and costs, and maintains bond strength under retort conditions, improving recyclability and simplifying the lamination process.
Implementation Method 1
an adhesive composition which comprises a polyol and a compound having isocyanate groups
Data Source
Figure 1
AI summary
The present invention is related to a laminate (1) for packaging applications, comprising a substrate layer (2) and an adhesive layer (5) present on a surface of said substrate layer (2), characterized in that said adhesive layer (5) is made from a one-component adhesive composition with an adhesive compound comprising a branched backbone structure and isocyanate moieties as functional groups. The present invention is furthermore related to an article, preferably, a flexible packing, comprising said laminate (1), and to a method for preparing said one-component adhesive composition.