Self-Bonding Polyurethane Adhesive for Orientation-Sensitive Bonding
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Solution Overview
Problem
Existing adhesives face challenges in applications where they cannot be easily applied or retained due to location or orientation issues, often requiring specialized equipment for metering and dispensing, and may flow away or be washed off by fluids, limiting their use in bonding large masses without melting or degrading into liquids.
Innovation Solution
A self-bonding, solid, non-tacky polyurethane composition with a main glass transition temperature above 40°C and at least 3.5% free isocyanate groups, which can be formed into various sizes and bonded under elevated temperature and moisture conditions, eliminating the need for liquid adhesives and specialized equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If liquid or pasty adhesives are used, then bonding capability is achieved, but the adhesive may flow away due to gravity or be washed away by surrounding fluids
Solution Approach 1:
The patent changes the physical state parameter of the adhesive from liquid/pasty to solid particulate form. The solid adhesive particles maintain their shape and position on substrates without flowing or being washed away, while still achieving bonding capability when activated by moisture and heat to form a polyurethane foam that cures in situ.
2Strength
If hot melt adhesives are used, then bonding is achieved through melting and re-solidification, but specialized equipment is required for metering and dispensing
Solution Approach 1:
The patent uses simple solid particulate adhesive material that can be applied without complex metering and dispensing equipment. The adhesive particles are applied directly to substrates and activated by moisture and heat to bond, eliminating the need for specialized hot melt equipment while maintaining bonding capability.
3Ease of operation
If solid adhesive materials are used, then handling and storage is simplified, but bonding capability is reduced compared to liquid adhesives
Solution Approach 1:
The patent utilizes phase transition of the adhesive material from solid particulate form (for easy handling and storage) to expanded foam form (for bonding). When moisture and heat are applied, the solid particles transform into a foaming polyurethane structure that provides strong bonding capability, thus resolving the contradiction between ease of handling and bonding strength.
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
Enables the formation of bonded masses from solid pieces without melting or applying liquids, allowing for easy handling and assembly of large bonded masses, suitable for forming agglomerated particles and molded articles, and replacing traditional adhesives in various applications.
Implementation Method 1
The self-bonding material would be capable of bonding to itself under predefined conditions, without melting or degrading to form a liquid that can run off
Implementation Method 2
bonded under conditions of elevated temperature, moisture and applied pressure
Implementation Method 3
The invention provides solid, non-tacky materials that can be stored and transported under ambient conditions without bonding to each other or sticking together, yet which will bond to each other under conditions of elevated temperature, moisture and applied pressure
Data Source
AI summary
Solid, non-melting polyurethanes having a glass transition temperature of at least 40°C and free isocyanate groups are self-bonding materials that are useful in a variety of adhesive and molding operations. Under conditions of heat and moisture, these polyurethanes will self-bond. The polyurethanes can be used as adhesive coatings, which are solid and non-tacky and thus can be transported and stored easily under ambient conditions. These polyurethane adhesives are especially useful in applications in which, due to the location and/or orientation of the substrates, liquid or melting materials cannot be applied easily or will run off the substrates.