Silane-Functionalized Rosin Adhesives for Ambient-Temperature Crosslinking
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Solution Overview
Problem
There is a need for isocyanate-free crosslinking systems that are curable at ambient temperatures to replace isocyanate crosslinkers in thermosetting compositions, which are commonly used in adhesive and coating applications, due to health concerns associated with isocyanate compounds and the challenge of achieving low-temperature curing without the use of heat.
Innovation Solution
A silane functionalized rosin composition is developed, which includes a compound with silane functionality derived from rosin acids or esters, capable of crosslinking at low temperatures through cycloaddition reactions, forming Si—O—C covalent bonds with hydroxyl functional polymers, and can be used in adhesive and coating applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If isocyanate crosslinkers are used in thermosetting compositions, then crosslinking performance and adhesion strength are improved, but health safety and environmental friendliness deteriorate due to isocyanate toxicity
Solution Approach 1:
The patent extracts and removes the harmful isocyanate component from the crosslinking system while retaining the desired crosslinking functionality through alternative chemistry. Specifically, it replaces isocyanate crosslinkers with silane-modified rosin esters that cure via moisture-induced condensation to form siloxane bonds, eliminating isocyanate toxicity while maintaining adhesion strength
Solution Approach 2:
The patent changes the chemical parameters of the crosslinking system by transitioning from isocyanate-based chemistry to silane-based chemistry. The silane-modified rosin esters contain alkoxy silane groups that hydrolyze and condense to form crosslinked networks, providing a fundamentally different but equally effective crosslinking mechanism without harmful byproducts
2Reliability
If conventional crosslinking systems are used, then crosslinking effectiveness is achieved, but curing temperature requirements increase, preventing ambient temperature curing
Solution Approach 1:
The silane-modified rosin esters possess self-curing capability through moisture-induced hydrolysis and condensation of alkoxy silane groups. This self-service mechanism allows the system to cure at ambient temperatures without external heating or catalysts, making the adhesive suitable for field applications and temperature-sensitive substrates
Solution Approach 2:
The patent introduces moisture from the environment as an intermediary that triggers and facilitates the crosslinking reaction. The water molecules mediate the hydrolysis of alkoxy silane groups, enabling crosslinking to proceed at low temperatures without requiring external energy input or additional catalysts
3Object-affected harmful factors
If bio-based materials are used to meet sustainability goals, then environmental friendliness is improved, but adhesion performance on difficult substrates deteriorates
Solution Approach 1:
The patent creates a composite material system by chemically modifying bio-based rosin esters with silane functionality. This combines the renewable, environmentally friendly nature of rosin with the superior adhesion and crosslinking properties of silane chemistry, resulting in a hybrid material that achieves both sustainability goals and high adhesion performance on challenging substrates
Solution Approach 2:
The silane modification introduces localized functional groups with high reactivity and affinity for diverse substrates. The alkoxy silane groups on the rosin ester molecules provide localized areas of enhanced adhesion capability, allowing the bio-based material to bond effectively to difficult-to-adhere surfaces while maintaining its overall green credentials
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 silane functionalized rosin composition provides effective crosslinking at ambient temperatures, resulting in adhesives with high peel and lap shear strengths, improved cure time, and enhanced properties such as solvent resistance, chemical resistance, and thermal stability, suitable for various applications including automotive, industrial, and marine coatings.
Implementation Method 1
capable of crosslinking at low temperatures through cycloaddition reactions, forming Si—O—C covalent bonds with hydroxyl functional polymers
Implementation Method 2
The silane functionalized rosin composition provides effective crosslinking at ambient temperatures
Implementation Method 3
forming Si—O—C covalent bonds with hydroxyl functional polymers
Data Source
AI summary
Disclosed are silane functionalized rosins having multiple functionalities. Such silane functionalized rosins are curable and thus capable of providing unexpected properties for various uses and end products. Also disclosed are synthetic routes to prepare silane functionalized rosins, which are formulated with hydroxyl functional polymers to provide curable adhesive compositions. The adhesives may be used for woodworking, automotive, textile, appliances, electronics, bookbinding, and packaging. Suitable substrates can be metal, polymer film, plastics, wood, glass, ceramic, paper, and concrete.