Mahendra K. Sharma

Advances in Waterborne Acrylic Resin/Polyester Polymer Blends and Their Applications: Part-A

Recent developments in waterborne polymers and polymer blends are discussed in relation to their use as a binder in several applications such as coatings, paints and ink systems. A process for the preparation of waterborne acrylic resins/polyester polymer blends that avoids the need for surfactants is described. It was found that these acrylic and polyester polymer blends can not be prepared without using this process. The stable polymer blends can be prepared with acrylic resins/polyester polymer ratios in the range of 10/90 – 35/65 (wt/wt). The higher solid content can be achieved by either incorporating low molecular weight acrylic resins or by adding 5.0 – 10.0 wt% alcohol. These polymer blends exhibit low viscosity (e.g. 40–200 cps) with 30 wt% solid content. The viscosity of the polymer blends can be adjusted by suitable thickener for a given application. Results indicated that the acrylic/polyester polymer blends exhibit superior pigment grinding and film properties as compared to the polyester or acrylic polymer alone.

Surfactants in Enhanced Petroleum Recovery Processes: An Overview

This paper reviews various aspects of surfactant flooding for enhanced petroleum recovery. Surfactants have been suggested and tested in several forms such as foams, macroemulsions and microemulsions to recover additional oil from petroleum reservoirs which is unrecoverable by conventional methods. Several important parameters such as optimal salinity, surfactant adsorption, surfactant/polymer interactions, ultralow interfacial tension, interfacial viscosity, emulsion and foam stability, foaminess, bubble size and size distribution, surface charge, and propagation of oil ganglia were described in relation to oil displacement in porous media. For the foam flooding process, the effect of polymer flooding on oil recovery was reported. Results indicated that the surface properties of the foaming agents significantly influenced the oil displacement, whereas bulk properties of the fluid in porous media did not influence the oil recovery. For microemulsion flooding, the optimal salinity of the system can be shifted to a desired value by varying the concentration and structure of the surfactant and cosurfactant. The surfactant formulations composed of petroleum sulfonates and ethoxylated sulfonates are relatively insensitive to divalent cations. Based on the experimental findings, a maximum in oil recovery was observed when a minimum in interfacial tension, apparent viscosity, surfactant loss and coalescence rate of oil droplets occurred at an optimal salinity.

Surface Phenomena in Coatings and Printing Technology

This paper describes various aspects of water-based coatings and printing processes with special emphasis on the surface characteristics of coating/printing films. The film formation depends significantly on the surface properties of formulated coating/ink, and their interactions with substrates. Several surface parameters in relation to coating defects are briefly described. The mechanisms of printing processes and coating/ink film formation by water-based systems are presented. It has been shown that the formation of surface tension gradient during film curing determines the quality of the coating and printing films. Results demonstrate that the incorporation of suitable additives in the formulation can considerably minimize the crater formation. The hydrophilic-lipophilic balance (HLB) concept and the effect of surfactant concentration on pigment dispersion in an aqueous medium are discussed.

Pigment Grinding Using Waterborne Acrylic Resin/Polyester Polymer Blends: Part-B

Several waterborne acrylic resin/polyester polymer blends were used for grinding pigments (e.g. millbases) for different applications such as waterborne inks, coatings and paints. Commercially available pigments contained mostly acrylic resins as a grinding vehicle. These pigments usually exhibited a limited applications with polyesters, when used as a binder in waterborne coating and ink formulations. In order to form compatible millbases, the pigments were ground with acrylic/polyester blends. It was found that the pigment millbases prepared with acrylic resin/polyester blends could be used with the acrylic polymers and/or polyester polymers in formulating waterborne coatings, paints and inks. The film properties of these waterborne coatings and inks were excellent. The water resistance of the film on paper, aluminum foil and polymer substrates was superior than that of the film containing polyester alone. The blocking temperature for film containing polymer blends was 20 – 30°F higher than that of the polyester containing films.

Water-Based Flexo and Gravure Inks Containing Eastman AQ Polyesters

The ink and overprint varnishes from water-dispersible Eastman®AQ polymers (e.g. polyesters) offer unique properties such as no amine odor, low foaming, easy clean-up, fast drying, high gloss, good resolubility, good transfer, good scuff and rub resistance, excellent adhesion on films and foils. Eastman polymers are also a good grinding vehicle for a variety of pigments and an excellent binder for the fluorescent and metallic pigments, resulting in super gloss flexo and gravure fluorescent and metallic ink systems with stability approaching six months or longer. These gravure and flexo inks and overprint varnishes demonstrated print quality and printing speeds equal to or superior to solvent inks. Eastman®AQ polymer containing inks are ideal ink systems for paper, board, aluminum foil and film substrates.

Formation of Ultrafine Silver Halide Particles in Microemulsions Useful for Photographic Technology

The formation of silver halide (AgX) particles in the size range of 30–100 A employing various microemulsions as a reaction medium has been investigated. It has been found that the size of AgX particles depends on the shape and size of the dispersed phase of the reaction medium. As shape and size of AgX particles play a prominent role in the formation of latent image during photography, the advantages of these ultrafine particles in the photographic emulsions are also described. In order to understand the process of ultrafine particle formation, several surfactant association structures formed by surfactant, cosurfactant, hydrocarbon and water are briefly discussed. An attempt was made to correlate the formation of AgX particles with dynamic structure of the reaction medium, e.g. microemulsion.

Advances in Water-Based Coatings and Printing Technology

Several aspects of coatings and printing inks have been reviewed with special emphasis on the recent developments of coating technology. The role of film forming materials and the progress in developing these products suitable for water-based technology have been discussed. The resins used in the coating and printing industries have been highlighted. Water-borne resins such as water-soluble and water-dispersible and their role in terms of end-use properties for desired applications have been described. The advantages and disadvantages as perceived by users of water-based coatings and printing formulations have been emphasized. It is likely that the present criteria of 80/20 (water/solvent) containing water-based systems will not last in the coming years due to strict environmental reasons, and development must be focused on formulating products with less than 5% volatile organic compounds (VOC). Several developments are made to achieve almost no VOC in the coating and printing systems to meet expected environmental regulations as well as to satisfy the customer demand for almost equal performance to solvent-based systems.