Rohm and Haas Company

Rohn and Haas Company

Martin Vogel

Alexander Kowalski

Peter Reeves Sperry

Willie Lau

Morris C Wills

Robert Mitchell Blankenship

Jiun-Chen Wu

Richard Roy Clikeman

William D Emmons

Ronald W Novak

Edward Charles Kostansek

Clarence J Neyhart

Jack C Thibeault

Kim Sang Ho

Charles Elwood Jones

Chao-Jen Chung

David Michael Fasano

Mark S Frazza

Robert R Raney

Rafael Gonzalez Aviles

Disclosed are uniformly sized domains of liquid crystals, a method for forming the domains, and their performance in polymer dispersed liquid crystal displays. The method provides the ability to form discrete domains of liquid crystal surrounded by a polymer shell, also known as polymer encased liquid crystals, or PELCs. Further, the method provides for the ability to make PELCs that have uniformly sized particles. Displays made comprising uniformly sized PELCs demonstrate markedly improved electro-optical performance over displays made by conventional polymer dispersed liquid crystal processes.

Particles and droplets containing liquid domains and method for forming in an aqueous medium

Titanium dioxide particles are dispersed in an aqueous medium with a polymeric latex which adsorbs to the surface of the titanium dioxide to give a low-viscosity slurry or pigment grind of composite titanium dioxide-polymeric latex particles. A high glass transition polymeric latex can be used as the dispersant, and a low glass transition temperature binder latex can be added. The zeta potential of the polymeric latex can be at least about 30 millivolts more negative than the zeta potential of the titanium dioxide. The adsorbed polymeric latex provides more optimal spacing of the titanium dioxide particles in films formed from coating compositions formulated using the composite particles, and consequently greater film opacity and hiding at a given pigment volume concentration. Coatings formulated using the composite particles can be prepared to give the same hiding as coatings including titanium dioxide dispersed with conventional polyelectrolyte pigment dispersants, but with lower levels of costly titanium dioxide. Alternatively, a single selected polymeric latex can be used to both strongly adsorb to the pigment particles and to serve as binder, or a mixture of a selected, strongly adsorbing polymeric latex having a low effective glass transition temperature and a conventional binder latex can be employed.

Process for preparing an aqueous dispersion of composite particles

Particles and droplets containing liquid domains and method for forming

Method for forming pluralities of droplets and polymer particles having

Droplets and particles containing liquid crystal and films and apparatus

A method is disclosed for improving the UV radiation absorption of a composition containing a UV radiation absorbing agent by adding from about 0.1 weight percent to about 50 weight percent of latex particles, based on total weight nonvolatiles. The latex particles contain a void and have a particle size of from about 100 nm to about 380 nm.

Method of improving ultraviolet radiation absorption of a composition

Inorganic material particles are dispersed in an aqueous medium with surface charge adjusting additives to give a moderately stable slurry or pigment grind. The dispersion can be used to prepare fully formulated compositions. Products formulated using the aqueous dispersion can be prepared to give the same performance as products including inorganic material dispersed with conventional polyelectrolyte pigment dispersants, but with higher levels of inorganic material, or superior performance properties with like levels of inorganic material.

Process for preparing an aqueous dispersion

The present invention is concerned with core and shell polymeric particles having microvoids in the core and one or more channels connecting the microvoids to the exterior of the particle. These particles, or LCAPs are produced by forming a core of polymeric acid, encasing the core in a shell polymer permeable to base, and then neutralizing the core such that the core swells, causing the shell to 'explode' in a controlled fashion. This controlled explosion causes channels to form in the shell. These particles can be used as control release devices for target compounds, to impart reinforcing properties to acrylic films, as an opacifying agent in coating compositions, and as a supplement or replacement of part or all of the pigmentary material or extenders that would otherwise be used in such coating compositions.

Synthesis of latex capsules

A method is disclosed for improving the erasability of erasable marking compositions, while maintaining the opacity of the coating and without producing burnishing, by incorporating into the compositions voided latex particles having a shell polymerized from either:

Method for improving erasability of erasable marking compositions

Method for improving erasability or erasable marking compositions

Uniformly sized polymer particles of 1-50 .mu.m diameter are made by gradually combining a water-insoluble monomer mixture with an aqueous dispersion of emulsion-polymerized polymer particles in the presence of a dispersion stabilizer and an oil-soluble, free-radical polymerization initiator.

Process for making controlled, uniform-sized particles in the 1 to 50

Multi-stage polymer particles containing one or more void space(s) therein are produced by sequential emulsion polymerization of an essentially low-acid earlier polymer stage, encapsulation of said low-acid polymer stage with at least a final polymer stage, contacting said polymer particles with a non-polymeric carboxylic acid or anhydride to permit the acid or anhydride to be absorbed into said low-acid polymer stage and swelling the polymer particles by contacting the particles with an aqueous base. The low-acid polymer stage is formed by emulsion polymerizing a monomer system comprising ethylenically unsaturated monomer(s) and containing less than 5% by weight of monomer(s) containing acid functionality. The low-acid polymer stage is swubsequently encapsulated by one or more polymer stages by emulsion polymerizing ethylenically unsaturated monomer(s) in the presence of the low-acid polymer stage. The final stage has a glass transition temperature (Tg) of about 50.degree. C. or greater, and the total polymer stages having a Tg of about 50.degree. C. or greater comprise about 60% or more by weight of the polymer particles. A non-polymeric carboxylic acid or anhydride is absorbed into the polymer particles and the resultant particles are contacted with base at a pH sufficient to swell the particles with water at a temperature near or above the Tg of the neat polymer or plasticized polymer of the final polymer stage. When dried the particles contain void space(s) therein which produce(s) opacity in compositions in which the particles are contained.

Multi-stage opacifying polymer particles containing non-polymeric acid

Multi-stage polymer particles containing one or more void space(s) therein are produced by sequential emulsion polymerization of an essentially low-acid earlier polymer stage, encapsulation of said low-acid polymer stage with at least a final polymer stage, contacting said polymer particles with a non-polymeric carboxylic acid to permit the acid to be absorbed into said low-acid polymer stage and swelling the polymer particles by contacting the particles with an aqueous base. The low-acid polymer stage is formed by emulsion polymerizing a monomer system comprising ethylenically unsaturated monomer(s) and containing less than 5% by weight of monomer(s) containing acid functionality. The low-acid polymer stage is subsequently encapsulated by one or more polymer stages by emulsion polymerizing ethylenically unsaturated monomer(s) in the presence of the low-acid polymer stage. The final stage has a glass transition temperature (Tg) of about 50.degree. C. or greater, and the total polymer stages having a Tg of about 50.degree. C. or greater comprise about 60% or more by weight of the polymer particles. A non-polymeric carboxylic acid is absorbed into the polymer particles and the resultant particles are contacted with base at a pH sufficient to swell the particles with water at a temperature near or above the Tg of the neat polymer or plasticized polymer of the final polymer stage. When dried the particles contain void space(s) therein which produce(s) opacity in compositions in which the particles are contained.

The present invention is concerned with the production and use of water-insoluble particulate heteropolymers made by sequential emulsion polymerization in dispersed particles of which a 'core' of a polymeric base is at least partially encased in a 'sheath' polymer that is permeable to an acid, such as acetic acid, adapted to cause swelling of the core by neutralization. The aqueous dispersion of the acid-swollen, base-containing core/sheath particles is useful in making water-base coating compositions, microvoids being formed in cores of the swollen particles in the film during the drying thereof. Thus, the heteropolymer dispersion can serve as an opacifying agent in coating compositions, such as water-base paints, as a supplement or replacement of part or all of the pigmentary material or extenders that would otherwise be used in such coating compositions. For convenience of description herein, the terms 'core', 'sheath', and 'core/sheath polymer' are frequently used to refer to the distinct functional components of the individual polymer particles of the essential 'mode' of the heteropolymers of the present invention even though in actuality, the components of the polymer particles thereof may not have the precise arrangement implied by this terminology.

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Jenkintown, PA, United States of America

Martin Vogel