Waterborne paints properties

The increasing importance of environmental considerations places new requirements on paint resins and has broadened the range of paint systems. Paints are now required that have a low solvent content (medium-solids, high-solids coatings) or are solvent-free (powder coatings), that can be adjusted by dilution with water (waterborne paints), and that are thermoplastic or capable of undergoing cross-linking. All of these properties must be obtained via the polymer structure of the binders. Important parameters are described below. 

As a result of the particulate nature of the binders only a low gloss and, in some cases, only limited corrosion protection can be obtained. Waterborne paints based on dispersions can be applied by spraying, however they are of only limited use for electrostatic coating and dipping applications due to their rapid drying properties. 

Uses Dispersant for org./inorg. pigments/extenders in waterborne all d-and acrylic paints, e.g., gloss and silk finish emulsion paints Features Permits prod, of emission-free paints Properties Lt. brn. clear liq. dens. = 1.05 g/cm (20 C) dynamic vise. 

Paint consists of a mixture of pigments which gives body and colour, and a resin or binder which is the actual film-forming component and acts as a glue to hold the pigment together and stick them to the surface. Binders include synthetic resins such as acrylics, polyurethanes, polyesters and epoxies and can be a combination of resins, e.g. epoxy/ acrylic and polyurethane/acrylic. To adjust the curing properties and reduce the viscosity so that the paint can be easily applied, a solvent or carrier is used. These evaporate after application and do not form part of the paint film. In waterborne paints, the carrier is water. With solvent-borne paints, also called oil-based paints, the carrier is a solvent such as acetone, turpentine, naphtha, toluene, xylene and white spirit. 

An overview is presented on the merits of polyurethane dispersions in waterborne paint formulations. In addition to the characteristics listed which they impart to coatings, such binders can offer an even wider range of properties by means of blending or copolymerisation, producing binders which are tailor made for specific applications, it is stated. 

The difference between solvent-borne and waterborne paints is due to the unique character of water. In most properties that matter, water differs significant from organic solvents. In creating a waterborne paint, the paint chemist must start from scratch, reinventing almost everything from the resin to the last stabilizer added. 

Forsgren, A. and Palmgren, S., Effect of Application Climate on Physical Properties of Three Waterborne Paints, Report 1997 3E, Swedish Corrosion Institute, Stockholm, 1997. 

Stringent legislations concerning the amount ofVOCs in all paint types have caused many companies to seek alternatives to solvent-borne paint systems, making the move to waterborne systems, the main focus of which is to improve film properties to the level of conventional solvent systems. Hence, a combination of CCTP and emulsion polymerization was explored as a method of creating additives for waterborne paints. ... 

Chem. Descrip. Blend of proprietary surface-act. substances Uses Deaerator and leveling aid used in almost all solv.-based and waterborne paint systems, free of silicones also exc. performance in inks and coil coatings Properties Yel. liq. flash pt. (Abel) > 100 C ref. index 1.49 Use Level 0.5-2% on total formula Drewplus S-684 [Ashland Hercules Water Technologies]... 

Colloidal silica dispersions have also been used in various waterborne paints, coatings and lattices as the silica nanoparticles can affect the properties of the resulting film [24]. However, aqueous colloidal silica dispersions have not reached their full potential in these applications, although a number of properties ofthe resulting films maybe improved. The reasons for this are the colloidal stability of the dispersion and coating formulation as well as the water resistance of dry film coatings containing silica particles. 

The appropriate amount of biocide carrier composition needed to yield a specified dry film concentration of biocide was added to a fixed quantity of waterborne acrylic paint and premixed using a high-speed disperser. This dispersion was then transferred to a Silverson-type mixer to obtain a finer dispersion. At this stage the influence of addition of silica or zeolite on the physical/mechanical properties of the paint film was assessed, though only minor changes in properties were noted, which could be eliminated by appropriate adjustments to the paint formulation. 

Polyester resins possess premium performance properties such as exterior durability, gloss, flexibility hardness, color stability, and versatility of cure. Polyesters are used in product finishes for household appliances, food and beverage containers, aircraft and equipment, automotive primers and bake coats, metal furniture, and fixtures. For example, water-soluble saturated polyesters are used in industrial baking paints, and in combination with melamine resin. Polyesters can be formulated in high solids and waterborne formulations to meet the requirements for the low VOC coatings being mandated by the EPA. 

To summarise the comparison between alkyd trim paints and their waterborne counterparts, a lot of properties are provided by solventbome alkyd technology for which specific additives are required in waterborne dispersion paints. Frequently, the polar alkyd resins are capable of wetting and stabilising the pigment for which dispersing agents are needed in waterborne. 

Waterborne bitumens may be anionic, cationic, or rarely nonionic emulsions, and are produced with the aid of emulsifiers and, if necessary, stabilizers conventionally used in the paint industry. The properties of bitumen paint (solutions and emulsions) (e.g., stability mechanical, weather, water, and chemical resistance corrosion protection properties) can be substantially improved by incorporating extenders. Suitable extenders include ground slate, ground limestone, chalk, talc, and mica (25 45 wt%, depending on extender type and required properties). The use of extenders... 

Characteristic properties of waterborne emulsion paints are relatively high solids contents (50-60 wt%), rapid dilution with water without any viscosity anomaly, and a low content of organic solvents (< 5%). 

Fillers are applied with electrostatic spraying devices (fast-rotating bells) to give dry film thicknesses of about 40 pm. Waterborne fillers with polyester-melamine binders (primer surfacers) have been developed to reduce the volatile organic content. They yield a film thickness of 30 pm after a prereaction time of 10 min at lOO C and a reaction time of 20 min at 165 °C. The properties of the films are similar to those formed by solventborne paints. More recently, waterborne fillers based on blocked isocyanates have been developed. Field trials have shown that their mechan-ieal resistance is very good. 

Uses Drier for waterborne oxidatively drying alkyd resin paints, esp. externally emulsified alkyd resin emulsions Features Lead-free, barium-free nonylphenol ethoxylate-ffee Properties Violet liq. water-emulsifiable dens. -1.09 g/cm (20 C) dynamic vise. 150-1000 mPa s flash pt. = 66 C 5% Co, 0.22% Li, 7.5% Zr Use Level 1-3% (on solid resin)... 

Uses Defoamer for waterborne disps., interior and exterior emuision paints, iarge to fine particie size disps. based on PVAc, PVC, acryiates and their copoiymers, disp. adhesives and piasters, giues, poiyvinyi ai-cohoi soi ns., gioss piastics, high gioss paints Features High efficiency shear-stabie aikaii resist, to pH 13 Properties Lt. yei. cioudy iiq. dens. 0.88 g/cm (20 C) dynamic vise. 

Uses Defoamer for waterborne architectural, maintenance, and OEM coatings, traffic paints, anticorrosive primers, marine topcoats, wood furniture coatings, waterborne flexo and gravure inks Regulatory FDA cleared, NV components Properties Sp.gr. 0.84 dens. 7.0 Ib/gal flash pt. > 149 C Dapro DF 1161 [Elementis Spec. U.S.j... 

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