Water-Based Spray Adhesive Shear Coagulation
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Solution Overview
Problem
Water-based pressure-sensitive adhesives (PSAs) require a long time for the adhesive particles to coalesce and develop PSA characteristics, which is inefficient compared to solvent-based adhesives that dry quickly.
Innovation Solution
A spray adhesive composition comprising an acrylic polymer, an emulsifier, and water, where the acrylic polymer includes monomer units of alkyl acrylate or alkyl methacrylate with at least 8 carbon atoms, and coagulates upon exposure to shear forces, such as those encountered when sprayed from a nozzle, allowing for rapid development of PSA characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water-based adhesive composition is used, then environmental safety and non-flammability are improved, but drying time and coagulation time increase significantly
Solution Approach 1:
The patent changes the chemical parameters of the adhesive composition by using long-chain alkyl acrylates (C8-C18) instead of conventional short-chain acrylates, and by adjusting the molecular weight and composition of the polymer to enable coagulation at lower temperatures and faster rates, thereby reducing drying time while maintaining water-based environmental safety
Solution Approach 2:
The patent utilizes phase transition through controlled coagulation of the polymer emulsion. The composition is designed to remain stable during storage but undergoes rapid coagulation when applied to the substrate, transitioning from a dispersed phase to a coalesced adhesive layer that bonds substrates together, eliminating the need for extended drying periods
2Object-generated harmful factors
If conventional water-based adhesive composition is used, then low VOC content is achieved, but PSA characteristics develop slowly
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating long-chain alkyl acrylates (C8-C18) and controlling the molecular weight distribution and composition of the polymer to enable rapid coagulation and PSA characteristic development within minutes, achieving both low VOC content and fast bonding performance
Solution Approach 2:
The adhesive composition is designed to be self-activating through shear-induced coagulation. When the composition is sprayed or applied to a substrate, the mechanical shear forces trigger immediate coagulation and development of PSA characteristics without requiring external additives, heat, or extended drying times, thereby achieving fast bonding while maintaining environmentally safe water-based formulation
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 composition quickly develops PSA characteristics within one minute of application, allowing for immediate bonding without the need for extended drying times, thus competing with the fast drying times of solvent-based adhesives.
Implementation Method 1
the composition coagulates upon being subjected to shear forces, for example, upon being sprayed from a nozzle
Data Source
AI summary
A composition includes an acrylic polymer, an emulsifier, and water. The acrylic polymer includes monomer units of at least one alkyl acrylate or alkyl methacrylate, wherein alkyl has at least 8 carbon atoms. Not more than one percent by weight of monomer units include a carboxylic acid, sulfonic acid, or phosphonic acid, based on the total weight of monomer units in the acrylic polymer. The composition is an emulsion of the acrylic polymer in water. The composition is a spray adhesive composition and/or coagulates upon being subjected to shear forces. A process for making the composition and a method for making a bonded article using the composition are also described.