Jul 30, This book builds up on the success of the first edition of Paints, Coatings, and Solvents. The first edition has been completely revised, the. Paints, coatings and solvents I Dieter Stoye ; Werner Freitag (ed.). Comprehensive information on all paint systems and binders, pigments, tillers. 1 Paint composition and applications — a general introduction. R Lambourne. Paint or surface coating? . The market for solvents in the paint industry.
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Different types of solvents-paints ranging from " waterborne coatings, low-solvent coating, solvent-free powder coatings, and new radiation-curing coating. Because of their beneficial performance properties and versatility, solvents have played an important role in the formula- tion of paints and coatings since the. fire-retardant, lacquer, latex, multicolor, organic coatings, paint, pigments, of pigments, plasticizers, extenders, activators, stabilizers, solvents, and diluents to.
The binder in many emulsion paints is based on homopolymers or co-polymers of ethenyl ethanoate vinyl acetate and a propenoate acrylic ester.
Ethenyl ethanoate is manufactured by passing a mixture of ethanoic acid vapour, ethene and oxygen over heated palladium ll and copper ll chlorides:.
Ethenyl ethanoate and an acrylic ester for example, methyl 2-methylpropenoate are then co-polymerized to form a random array, in which these groups link into a linear chain:. Other acrylic esters used as co-monomers with ethenyl ethanoate are ethyl propenoate, butyl propenoates, or a co-polymer of butyl propenoate and methyl 2-methylpropenoate.
The polymers used in these paints are carried in water water-borne emulsion paints which as described above are much better for the environment than paints in which the binders are in organic solvents. Emulsion paints are so-called as they are made by a process known as emulsion polymerization , in which the liquid monomers to be polymerized are first dispersed in water, as an emulsion. The polymers produced by this process typically have relative molecular masses of - 1 As such they are useful only as dispersions since they would be extremely viscous if they were carried in solution and this would make them unusable.
Figure 3 Graph showing relationship between relative molecular mass and viscosity for solution and dispersion polymers. Acrylic resins may also be used in industrial paints, either as water-borne emulsion paints or as solvent-borne paints.
Solvent-borne industrial paints can have a tough protective finish and are widely used in industry as topcoats, for example on car bodies. The paint frequently comes as two components which are mixed together just before use: The resulting polyester has numerous hydroxyl groups -OH pendant from the polymer backbone. The hydroxyl groups react with the other compound often consisting of a polymeric isocyanate such as a trimer of 1,6-diisocyanatohexane hexamethylene diisocyanate:.
Such a compound is known as a crosslinker for it produces, on reaction with the resin, a three-dimensional structure similar to the polyurethane formed from a polyol and an isocyanate.
When these two components are mixed together, a chemical reaction takes place between the hydroxyl groups on the polymer acrylic resin and the isocyanate groups on the cross linker:. This reaction proceeds relatively slowly at room temperature, allowing enough time for the paint to be applied, after which the solvent thinner evaporates and the painted item is placed in an oven to accelerate the chemical reaction.
This greatly increases the molecular mass of the polymer causing it to become a three-dimensional molecule and form a hard film, resistant to chemicals. Decorative gloss paints typically contain alkyd polymers resins. A typical resin is that produced from a polyol such as propane-1,2,3-triol glycerol with a dibasic acid such as benzene-1,2-dicarboxylic phthalic anhydride and a drying oil linseed or soybean oil. On being heated together, ester linkages are formed, and water is a by-product.
The name alkyd is derived from alcohol and anhydride.
The first step in making the alkyd polymer is the reaction between the triol and the drying oil to produce a monoglyceride. For example:.
The alkyd resins, which generally have relative molecular masses in the range of 10 - 50 , are usually carried in organic solvents solvent-borne paints.
Turpentine extracted from trees was used in the past as the solvent, but this has been replaced by solvents from petrochemical feedstock, such as 'white spirit' which is a mixture of aliphatic and alicyclic hydrocarbons.
Once the alkyd resin is applied, the pendant oil drying groups react with oxygen in the air to form a cross-linked, hard thermoset coating, with a high molecular mass. Epoxy resins are often used as the binder in industrial coatings primers.
Paints, Coatings and Solvents (2nd ed.)
They give the paint excellent adhesion together with high resistance to chemicals corrosion , and physical resistance necessary, for example, on ships and chemical storage tanks. The epoxy resins are made from 1-chloro-2,3-epoxypropane produced from 3-chloropropene and substituted phenols, such as bisphenol A:.
The value of n can be controlled to give a range of resins varying from viscous liquids to solids with high melting points. Epoxy resins can be carried in solvents such as aromatic hydrocarbons, alcohols, ketones and esters solvent-borne paints or as dispersions in water water-borne paints as true emulsions. They are not normally used in topcoats for outdoors because they are susceptible to UV degradation, but they make excellent interior coatings and exterior primers.
Pigments give colour and opacity to paints. Amongst the organic pigments, particularly important are azo- , phthalocyanine and anthraquinone derivatives. It has a high refractive index and gives a 'gloss' to the paint.
Another widely used inorganic pigment is finely divided calcium carbonate. This has a low refractive index and is used, together with titanium dioxide, to produce 'matt' paints. Other pigments include iron oxides black, yellow and red , zinc oxide and carbon black.
The functions of paints: Protection of the part surface from the environmental factors Oxygen and other chemically active gases, moisture, dissolved salts and other chemicals, temperature, bacteria, fungi. Corrosion protection is the most important function of paints. Aesthetic appearance provided by the paint color and sheen eggshell, satin or gloss.
Providing a desired ability of reflection-absorption of heat and light. Changing the surface properties: Classification of paints by physical type.
Classification of painting products by their functions. Solvent-borne paints dry fast and may contain a wide range of binders. The main disadvantages of the solvent-borne paints are their toxicity and combustibility. Water-borne paints contain water as the paint solvent.
Waterborne paints are non-toxic and non-combustible but they are characterized by long drying time due to slow evaporation rate of water. There are numerous electrostatic methods available. Dipping used to be the norm for objects such as filing cabinets, but this has been replaced by high speed air turbine driven bells with electrostatic spray.
Car bodies are primed using cathodic elephoretic primer, which is applied by charging the body depositing a layer of primer.
The unchanged residue is rinsed off and the primer stoved. Many paints tend to separate when stored, the heavier components settling to the bottom, and require mixing before use. Some paint outlets have machines for mixing the paint by shaking the can vigorously for a few minutes.
Resins and additives for powder coatings and alkyd paints, based on renewable resources
The opacity and the film thickness of paint may be measured using a drawdown card. Water-based paints tend to be the easiest to clean up after use; the brushes and rollers can be cleaned with soap and water. Proper disposal of left over paint is a challenge.
Sometimes it can be recycled: Old paint may be usable for a primer coat or an intermediate coat, and paints of similar chemistry can be mixed to make a larger amount of a uniform color. To dispose of paint it can be dried and disposed of in the domestic waste stream, provided that it contains no prohibited substances see container.
Disposal of liquid paint usually requires special handling and should be treated as hazardous waste, and disposed of according to local regulations. Russia , Tver City , Blue colour paint smears Primer is a preparatory coating put on materials before applying the paint itself.
The primed surface ensures better adhesion of the paint, thereby increasing the durability of the paint and providing improved protection for the painted surface. Suitable primers also may block and seal stains, or hide a color that is to be painted over. Emulsion paints are water-based paints in which the paint material is dispersed in a liquid that consists mainly of water.
For suitable purposes this has advantages in fast drying, low toxicity, low cost, easier application, and easier cleaning of equipment, among other factors. Flat Finish paint is generally used on ceilings or walls that are in bad shape. This finish is useful for hiding imperfections in walls and it is economical in effectively covering relatively great areas.
However this finish is not easily washable and is subject to staining. Matte Finish is generally similar to flat finish, but such paints commonly offer superior washability and coverage. See Gloss and matte paint.
Eggshell Finish has some sheen, supposedly like that of the shell on an egg. This finish provides great washability, but is not very effective at hiding imperfections on walls and similar surfaces. Eggshell finish is valued for bathrooms because it is washable and water repellent, so that it tends not to peel in a wet environment. Pearl Satin Finish is very durable in terms of washability and resistance to moisture, even in comparison to eggshell finish.
It protects walls from dirt, moisture and stains.
Accordingly, it is exceptionally valuable for bathrooms, furniture, and kitchens, but it is shinier than eggshell, so it is even more prone to show imperfections. Semi-Gloss Finish typically is used on trim to emphasise detail and elegance, and to show off woodwork, such as on doors and furniture.
It provides a shiny surface and provides good protection from moisture and stains on walls.
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Its gloss does however emphasise imperfections on the walls and similar surfaces. It is popular in schools and factories where washability and durability are the main considerations.
It pairs well with other finishes. While it is highly durable and easy to clean, high gloss paint is known for obvious visibility of imperfections like scratches, dents .
Varnish and shellac are in effect paints without pigment; they provide a protective coating without substantially changing the color of the surface, though they can emphasise the colour of the material. Wood stain is a type of paint that is formulated to be very "thin", meaning low in viscosity, so that the pigment soaks into a material such as wood rather than remaining in a film on the surface.
Stain is mainly dissolved pigment or dye plus binder material in solvent.USB1 en. Incorporation of small amounts of other diols and trifunctional components was found to improve color and coating properties. Paint canning is a completely automated process. Usually it is a rapidly drying formulation. Paint manufacturers utilize an extensive array of quality control measures.