Aqueous Particle Dispersion and Process for Forming an Aqueous Particle Dispersion

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This patent describes a method for making aqueous dispersions of particles with a polymer coating that enables uniform film formation when the dispersion dries, effectively suppressing the 'coffee ring effect' (the uneven particle distribution often seen when a droplet dries). The process involves coating various types of solid core particles with a monolayer of a high molecular weight, water-soluble, interfacially-active polymer, then removing excess free polymer to achieve specific surface tension values that promote homogeneous drying. The resulting dispersion can be used to create films with uniform particle coverage on a surface.

Use CasesContent extracted from patent full text and abstract with AI.

• Inkjet printing inks to ensure uniform color density and image quality without coffee ring defects.
• Coatings or paints where even distribution of pigments or functional particles is critical (e.g., display technologies, touchscreens, decorative coatings).
• Printed electronics, including the deposition of conductive, dielectric, or semiconducting particle-based films.
• Manufacturing of biomedical diagnostic devices that require reproducible deposition of nanoparticle arrays or bioassays.
• Spray drying or drop casting processes for pharmaceutical formulations or catalysts where homogenous film or powder formation is needed.
• Optical coatings or films for sensors where particle uniformity impacts device performance.

BenefitsContent extracted from patent full text and abstract with AI.

• Effectively eliminates the coffee ring effect, ensuring even particle distribution in dried films.
• Universal across a wide range of particle materials, shapes, and polymers, making it highly versatile.
• Does not require modification of substrates or the addition of surfactants beyond the polymer shell, simplifying formulation and reducing impurities.
• Leads to homogeneous, single-layer coatings that improve the reliability, accuracy, and appearance of printed or coated products.
• Easily adapted to conventional industrial processes like inkjet printing, spray drying, and coating, facilitating adoption.
• Improved reproducibility and process control due to the defined surface tension window and monolayer coating approach.

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Inventors & Applicants

Patent Abstract

The present invention relates to a process for producing an aqueous particle dispersion comprising the steps of: a) providing a dispersion consisting of water and solid core particles, b) providing an aqueous solution of a water-soluble, interfacially-active polymer having a molecular weight of more than 10 kDa, c) mixing said aqueous dispersion of solid core particles with said aqueous polymer solution, d) removing free polymer from the obtained mixture; wherein, in step c), the amount of the water-soluble, interfacially-active polymer mixed with said aqueous dispersion of solid core particles exceeds the amount of polymer required to coat the surface of each of the solid core particles with a monolayer of the polymer, and wherein step d) is repeated until the surface tension of the resulting modified particle dispersion is in a range of from 60 to 72 mN/m, preferably from 65 to 72 mN/m and more preferably from 67 to 72 mN/m. The present invention also relates to an aqueous particle dispersion exhibiting a homogenous drying pattern as well as a film made thereof and the use of the aqueous particle dispersion.