Solvent-Free Powdered Adhesive for Non-Planar Surfaces
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Solution Overview
Problem
The challenge lies in creating a powdered heat-activatable adhesive that can be uniformly applied to complex non-planar surfaces without agglomeration, maintaining a dry and non-tacky state at ambient temperature, and ensuring uniform bond strength, which is difficult with conventional adhesives like extrusions or tapes.
Innovation Solution
A solvent-free powdered adhesive with particle sizes between 20 to 150 microns, prepared at temperatures below -10°C, is used, which is flowable below the activation temperature and transforms into a non-oriented fused layer upon heating, allowing for electrostatic spraying and subsequent cross-linking to form a strong adhesive bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If adhesive is applied by extrusion or tape to complex non-planar surfaces, then application is simple, but uniform layer thickness cannot be achieved
Solution Approach 1:
The patent replaces mechanical application methods (extrusion, tape) with electrostatic spraying to deliver adhesive particles to complex surfaces. The electrostatic field enables uniform distribution of particles across non-planar geometries while maintaining ease of application through automated spray delivery systems.
Solution Approach 2:
The adhesive is formulated as charged particles with specific size distributions (D10-D90 ratio) and charge characteristics. These parameter changes enable the particles to be uniformly deposited via electrostatic spraying while maintaining proper adhesion properties, resolving the contradiction between application simplicity and layer uniformity.
2Manufacturing precision
If adhesive powder is created without particle agglomeration, then uniform distribution is achieved, but particle flowability is reduced
Solution Approach 1:
The patent specifies precise particle size parameters (D10-D90 ratio between 1.2-2.0) and charge parameters to optimize both flowability and uniform distribution. The particles are formulated with controlled charge density and size distribution that simultaneously enables good flow during handling and uniform electrostatic deposition on substrates.
Solution Approach 2:
The patent uses a charged carrier medium or electrostatic field as an intermediary to transport adhesive particles without agglomeration. This intermediary mechanism allows particles to remain individually dispersed during delivery while maintaining their flowability characteristics, resolving the contradiction between uniform distribution and flowability.
3Ease of operation
If adhesive remains dry and non-tacky at ambient temperature, then handling is improved, but adhesion activation is delayed
Solution Approach 1:
The adhesive particles are formulated with specific glass transition temperatures and molecular weights that maintain a dry, non-tacky state at ambient temperatures for easy handling. The formulation parameters (polymer architecture, crosslink density, moisture content) are controlled to ensure the adhesive remains stable during storage and handling but activates properly when exposed to service conditions such as heat or moisture.
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 method ensures uniform adhesive bonds on complex surfaces with strength comparable to conventional adhesives, maintaining mechanical properties and preventing premature activation during storage or transportation, with the adhesive remaining dry and non-tacky until heat activation.
Implementation Method 1
electrostatically delivering particles for forming a precursor layer to the at least one first surface
Implementation Method 2
physically transformed to form a substantially non-oriented fused precursor layer film that is tack-free and dry to the touch
Implementation Method 3
subjected to a reaction activation condition to cause cross-linking and to define a cross-linked reaction product material that adhesively bonds the at least one first substrate with the at least one second substrate
Data Source
AI summary
An adhesive comprising a solvent free powder of average particle size in the range 20 to 300 preferably 20 to 150 microns is heat activated at a temperature in the range 140° C. to 220° C., is flowable at a temperature below the heat activation temperature and is dry and non-tacky to the touch at ambient temperature, the use of a powdered adhesive is particularly useful for bonding of non-planar surfaces with complex contours.