High-Solids Pressure Sensitive Adhesive Dispersion with Low Viscosity
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Solution Overview
Problem
Water-based pressure sensitive adhesives with high solids content often face difficulties in achieving low viscosity while maintaining coatability and processing ease, as high solids content can lead to high viscosity, making it challenging to efficiently coat and process the adhesive composition.
Innovation Solution
A water-based pressure sensitive adhesive dispersion is created through simultaneous micro-suspension and seeded emulsion polymerization, resulting in a bimodal particle size distribution and a composition with high solids content (>65%) and low viscosity (<300 centipoise) by using a monomer solution with water-insoluble monomers and an aqueous phase containing a latex binder, surfactant, and polymeric suspension stabilizer, which are mixed and heated under an inert atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high solids content is used in water-based pressure sensitive adhesives, then drying rate and line speed are improved, but viscosity increases making coatability and processing difficult
Solution Approach 1:
The patent changes the physical and chemical parameters of the adhesive system by using high solids content formulations (greater than 60% solids) with specific monomer compositions and polymer architectures that maintain low viscosity despite high concentration, enabling both fast drying and good coatability
Solution Approach 2:
The patent creates composite adhesive systems combining multiple polymer components including carboxyl-containing polymers and epoxy-functional polymers that work synergistically to achieve the desired balance between high solids content, low viscosity, and adequate adhesive performance
2Ease of manufacture
If high solids content is used in water-based pressure sensitive adhesives, then manufacturing cost is reduced, but viscosity increases making processing difficult
Solution Approach 1:
The patent optimizes formulation parameters including monomer ratios, polymer composition, and additive selection to achieve high solids content formulations that remain processable, reducing water content and associated manufacturing costs while maintaining manufacturing feasibility
Solution Approach 2:
The patent introduces specific functional components at targeted concentrations (e.g., carboxyl-containing polymers, epoxy-functional polymers) that locally enhance adhesive properties and processability without significantly increasing overall viscosity or manufacturing complexity
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 method produces a dispersion with improved coatability and processing ease, allowing for faster drying rates and higher line speeds in coating applications, while maintaining strong adhesive properties in products like tapes and labels.
Implementation Method 1
from about 0.01 to 0.2 parts monomer soluble free radical initiator
Implementation Method 2
from about 0.1 to 2 parts surfactant
Implementation Method 3
heating the monomer solution-aqueous phase mixture under an inert atmosphere
Data Source
AI summary
A water-based pressure sensitive adhesive dispersion is provided. The dispersion is a reaction product of a monomer solution and an aqueous phase. The monomer solution contains from about 40 to 70 parts water-insoluble monomer selected from the group consisting of alkyl acrylate, methacrylate, vinyl ester, and combinations thereof and from about 0.01 to 0.2 parts monomer soluble free radical initiator. The aqueous phase includes from about 1 to 20 parts latex binder, from about 0.1 to 2 parts surfactant, from about 0.02 to 1 parts polymeric suspension stabilizer, and water as a remaining balance. All parts are given as parts by weight per 100 parts of the dispersion. The dispersion has a solid phase of at least 60 weight percent, a viscosity of less than about 300 centipoise, measured at about 23° C., and a bimodal particle size distribution.