Isocyanate-Terminated Silane Adhesives for Lamination Stability
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Solution Overview
Problem
Conventional amino silane compounds used in laminating adhesives often result in shortened potlife, haziness, or precipitation, making them unsuitable for lamination applications, especially in food packaging and industrial laminations where improved temperature and chemical resistance are required.
Innovation Solution
The development of isocyanate-terminated silane compounds, which are clear and stable, are incorporated into the isocyanate component of two-component adhesive compositions, overcoming the limitations of traditional amino silanes by providing improved heat and product resistance without the trade-offs of shortened potlife or haziness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional amino silane compounds are used in laminating adhesives, then temperature and chemical resistance are improved, but potlife is shortened and haziness or precipitation occurs
Solution Approach 1:
The patent changes the chemical parameter of the silane compound from conventional amino silane to isocyanate-terminated silane, which fundamentally alters the reactivity profile. This parameter change allows the silane to remain stable during storage (extended potlife) while still providing the desired temperature and chemical resistance when cured, resolving the contradiction between reliability and duration of action.
Solution Approach 2:
Instead of using amino silane that reacts quickly with isocyanate (causing short potlife), the patent inverts the approach by using isocyanate-terminated silane where the isocyanate group is already present in the silane structure. This inversion eliminates the need for amino group reaction and prevents the harmful side reactions that cause precipitation and haziness, while maintaining the adhesion promotion and resistance properties.
2Reliability
If conventional amino silane compounds are used in laminating adhesives, then adhesion promotion is improved, but haziness and precipitation occur
Solution Approach 1:
The patent changes the functional group parameter of the silane compound from amino group to isocyanate-terminated group. This parameter change eliminates the high reactivity between amino groups and isocyanate that causes precipitation and haziness, while preserving the adhesion promotion capability through the silane's ability to form strong bonds with substrates and participate in the polyurethane network formation.
Solution Approach 2:
The isocyanate-terminated silane acts as an intermediary that bridges the gap between adhesion promotion and compositional stability. The silane group provides adhesion to substrates, the isocyanate groups participate in polyurethane network formation, and the overall structure remains stable and clear during storage, avoiding the precipitation and haziness problems of conventional amino silanes.
3Reliability
If amino silane is incorporated in the isocyanate-reactive component, then adhesion promotion is improved, but reactivity causes shortened potlife and precipitation
Solution Approach 1:
The patent inverts the conventional approach by placing the isocyanate groups within the silane structure itself rather than having amino silane react with separate isocyanate. This inversion allows the silane to function as both adhesion promoter and isocyanate source, simplifying the system and eliminating the need to control the reactivity of free amino groups with isocyanate, thus avoiding potlife shortening and precipitation issues.
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 isocyanate-terminated silane compounds enhance the bond strength, temperature resistance, and chemical resistance of the adhesive compositions, making them suitable for food packaging and industrial laminations while maintaining extended potlife.
Implementation Method 1
a two-component adhesive composition comprising (A) an isocyanate component comprising: (i) an isocyanate; and (ii) an isocyanate-terminated silane compound that is the reaction product of a polyisocyanate and an isocyanate-reactive compound comprising a silane group and at least one isocyanate-reactive group
Data Source
AI summary
The disclosed adhesive compositions comprise (A) an isocyanate component comprising (i) an isocyanate and (ii) an isocyanate-terminated silane compound. In some embodiments, the isocyanate-terminated silane compound (ii) is the reaction product of a polyisocyanate and an isocyanate-reactive compound comprising a silane group and at least one isocyanate-reactive group selected from the group consisting of —OH, —SH, and —NHR, where R stands for an alkyl remainder having from 1 to 12 C atoms or a cycloaliphatic or aromatic remainder having between 6 and 12 C atoms. In other embodiments, the isocyanate-terminated silane compound (ii) is the reaction product of a polyisocyanate selected from the group consisting of isophorone diisocyanate, m-xylylene diisocyanate, mixtures thereof, dimers thereof, trimers thereof, prepolymers thereof, and combinations thereof and an isocyanate-reactive compound comprising a silane group and at least one isocyanate-reactive group of —NH2. Methods for preparing the disclosed two-component adhesive compositions, and methods for forming laminate comprising same, are also disclosed.