Types of paints and varnishes

Among the water painting materials the most common are lime, silicate, cement paints. The separate group is formed by water-emulsion mixtures.

Lime paints are obtained at the basis of lime paste which is diluted to consistency of "milk" and alkali-proof pigments (ochre, chromium oxide (green rouge), iron minium, ultramarine blue and others). For the increasing of resistance potassium aluminum sulfate (alum) or cooking salt are added. The variety of lime paints are dry mixtures on the basis of the ground lime and calcium chloride with alkali-proof pigments.

Lime mixtures are used for painting of facades and internal brick, plaster and concrete surfaces.

Lime paints have comparatively low strength and longevity.

Glue paints are mixtures of pigment, filler - usually chalk, and finely divided glue. Before using the paints are dissolved in water to painting consistency. They are not water-resistant, intended for the internal finishing of plastered surfaces. On reason the wide application of synthetic film-forming substances at production of paints, glue mixture have lost their value.

Silicate paints are the suspensions of alkali-proof pigments and silica fillers in potassium liquid glass. The use of liquid sodium glass is the reason of appearance on the painted surface of white color salt efflorescence. Paints harden as a result of formation of low soluble silicates. It is recommended to use them in moist terms exploitation for painting of brick and plastered facades, and also for the internal finishing.

Cement paints are manufactured on the basis of Portland cement and alkali-proof pigments. For the improvement of properties there added up to 15% water-retaining admixture - dry hydrated lime, 2-4% accelerate of hardening - calcium chloride and 1% water-retaining agent - calcium stearate and others in their composition. Paints are weatherproof. They are used for the external and internal painting at stone, brick, concrete, plaster and other porous surfaces which are preliminary moistened. At dilution of cement paint in polyvinylacetate, perchlorovinyl and others water emulsions of polymers polymer-cement paints are obtained. They are characterized by good adhesion with different construction materials, raised weather-resistance, elasticity, ability to harden at low humidity.

Water-emulsion and water-dispersion paints are emulsions or suspensions of pigments and fillers in the film-forming aqueous dispersions of polymers with the additives of emulsifiers, stabilizers and other substances. Depending on the form of polymer water-emulsion paints there are polyvinyl acetate, rubber, polyacryl and others. They are used for the internal and external works. Paints for the internal works are not recommended to use in the premises with the increased humidity.

Paints on the basis of vinyl acetate polymers, copolymers of the styrene with the phenylbutazone, acrylate copolymer are the most widely used.

Quantity of film-forming substance in the paints of this type is 40-55%. Facades of buildings, external wooden surfaces are painted mostly by polyacrylate emulsion paints, styrene- polyvinyl acetate and butadiene paints are used predominantly for interiors.

Water paints do not have a smell practically. Painting coatings have the high adhesion almost to all basements and good performance parameters. It is possible to paint humid surfaces by them; they are non-combustible, permit the water vapor and promote the comfort of dwellings. Physical properties of the water paints depend on the type of polymer, which is applied as binding agent. So, paints based on the polyvinyl acetate have the low water-resistance. They are applied mainly for coloring of ceilings and internal walls in the dry premises. Butadiene-styrene dispersions have the good water resistance; however they are characterized by limited light fastness.

Acryl paints are the most universal and compose the most considerable part of the water paints. They can be produced with a great number of different colors and save the color at intensive ultraviolet irradiation. Acryl paints allow creating elastic coatings; they are durable, and resistant to washing.

Basic specification of acryl paints "Ceresit "are resulted in Table 18.5.

Таble 18.5

Description of acryl paints "Ceresit"

Usually, water paints deteriorate their properties at freezing, therefore in cold time they must be kept in the heated premises.

The water-dispersed organic-silicon (silicon) paints impart the hydrophobic properties to the coatings that substantially increase their durability. Paints, based on the silicon resins combine the best properties of acryl and silicate paints.

Before the application, paint can be diluted by water till viscosity for required the spreading by paint sprayer or by roller and brush. The period of practical drying of the basic types of water-emulsion (water-dispersion) paints - is less than 1 hour.

Oil paints are the suspensions of pigments in drying oil. If required fillers, siccatives and other admixtures are added to their composition. Paints are produced doughy or ready to use. They are used for the different types of painting on a metal, wood, plaster, concrete, taking into account quality of drying oil and type of pigment. Thus, for instance, mixtures with the use oxidized drying oil are suitable for the painting of surfaces inside the premises, in contrast to the paints on the natural and gliptal drying oils, which are intended for the using both on the internal and external coatings.

At application of white lithopone, which darkles under the action of light, there is not possible to use oil paints for external painting works, and white lead which contain harmful matters are not recommended for painting of internal surfaces of housings apartments.

The whitened oil paints with the reflection coefficient by 50-70% are recommended to use in the official and working premises of the buildings of public and industrial destination, with the reflection coefficient by 30-40% - in the vestibules and on the staircases, the corridors, which do not have natural illumination, but it is less than 30% - in all auxiliary premises, if their light regime do not present the increased requirements.

It is required to paint only the dry surfaces with oil paints and coating them with the thinnest skim. Humidity of plaster should not exceed 8 %, and wooden surfaces - 12%. Painting on the incompletely dried previous layer is not allowed.

In the winter conditions, painting with the oil paints inside the apartments can be made at a temperature not below than 8 °C (temperature is measured in the distance at 0.5 m from a floor).

For the priming it is possible to use drying oil, into which 5-10% of pigments are introduced. At the treatment of wooden and concrete smooth surfaces into the drying oil dry pigments usually are added, at the treatment of the plastered and metallic surfaces - the paste paints are used. Ocher, Indian red or their mixture (for the metal is used only Indian red) are applied.

Enamel paints are the variety of painting mixtures for which solutions of synthetic polymers as the binders are used. Process of film-formation of enamel paints goes at evaporation of organic solvents.

In the construction perchlorvinyl, pentaphthalic, glyptal, epoxy and other enamel paints are widely used. Each of them has their rational range of uses. So pentaphthalic enamels are rationally used for coating of wood floors, perchlorvinyl for the painting of the facades of houses, glyptal - internal elements of houses on plasters, wood and metal.

Enamel paints are dissolved in petrol, solvent, turpentine, xylol, toluene and some other substances.

Enamels form a solid layer with intensive glance after drying. The types of enamels are conditioned by the polymeric binders applied.

Drying film in the enamel paints occurs as a result of the evaporation of volatile solvent and simultaneous hardening of polymeric bonding agent on the surface. Enamel paints are produced usually ready to use. They can include plasticizers, hardeners, accelerators of drying, stabilizers, antirots, surface-active substances (SAS) and other special admixtures. Enamel paints are used for the external and internal painting on the metal, the wood, the plastering. Light resistance, the chemical stability and resistance to weather effect are characteristic for them.

Enamels are coated at primed surface. They protect the surfaces of constructions from the action of the environment; give them decorative appearance and some special properties.

Perchlorovinyl enamels are resistant to the action of the most mineral acids and alkalis of different concentration at a temperature 60 °C, however not resistant to the action of oxidants, concentrated sulfuric and nitric acids, hydrocarbons. They dry out quickly and form the durable semiglance film. It is recommended to apply enamels at the temperature not below 8°C. Coatings from the perchlorovinyl enamels disintegrate at heating higher than 60-80°C with the release of hydrogen chloride vapor.

Epoxy enamels are characterized by the high adhesion to the metals and non-metals, hardness and resistance to the corrosive environments. Epoxy enamels are usually double-base; they consist of suspensions of coloring pigments in solution of epoxy resin and the hardener. The diethylenetriamine and polyethylenepolyamine can be the hardeners.

Epoxy paint-and-varnish materials can be cold and hot hardening. At coloration by the materials of cold hardening, the temperature of air should be provided not below 15 °C.

Epoxy enamels are toxic and inflammable materials, that is explained by properties of solvents and hardeners, which applied at their making. After drying out coatings do not influence harmful on the human organism.

Epoxy enamels are placed by the method of airstream atomization.

Glyptal enamels are the suspensions of the pigments and fillers in glyptal varnish with admixtures of the siccative and solvent. Enamels are diluted to the required viscosity by lacquer petroleum, turpentine, xylene, solvent or their mixture.

It is possible to apply enamels, consisting of the glyptal varnish and aluminum powder (6-12 %) for an anticorrosive protection. Their heat-resistance is up to 300°C.

It is not recommended to apply glyptal enamels at the surfaces, on which direct solar radiation, precipitations and biological factors affect.

Pentaphthalic enamels are made on the basis of the phthalic anhydride and pentaerythrite in mixture with pigments, fillers and solvents. They form more atmosphere resistant, compliant, waterproof, proof to the temperature oscillations and mechanical influences coatings compared to glyptal.

At adding aluminum powder to the pentaphthalic varnish heat-resistant coatings (up to 300 °C) are obtained. Enamels before the use are diluted to the working viscosity by the solvent, xylene, lacquer petroleum.

Organic-silicon enamels differ by resistance to the action of high and low temperatures and their cyclic difference, the high insulating properties, oil-, gasoline- and freeze-resistance.

Powder paints are the fine powders which including synthetic resins, hardening agents, pigments and other admixtures. They are polymerized at 140-200 ⁰C and form uniform film. They have the high longevity and adhesion to the covered surfaces. Due to the absence of solvents, powder paints have less shrinkage and porosity. The method of coloring allows to form ideally flat and smooth surfaces which characterized by the high resistance to the different types of influences and good corrosion resistance.

Powder paints are classified: depending on the type of resins - epoxy, epoxy-polyester, polyester, acrylic, polyurethane; depending on the type of the formed surfaces - smooth, shagreen and other; depending on the degree of glance of surfaces - glossy, semigloss, semi-matt, matt.

Coloration by the powder paints does not require priming of surfaces. Before coloring of powder paint, preparation of surface is made by the methods of defatting and phosphatization. Paints are putted mainly on metallic and glass surfaces by the method of spraying. It is difficult to get the thin-coat finishes (10-20 mm) using the powder paints.

Varnishes which are used for construction works divided by the followings groups: oil-resin, not oil synthetic, on the basis of bitumens, nitro- and ethylcellulose, spirit.

Properties and application of varnishes is determined by properties of organic binders. For example, varnishes on the basis of urea-formaldehyde, polyester polymers are used for painting of parquet floors, for the finishing of plywood, millworks, wood particle hardboards. Pentaphthalic varnishes are applied for varnishing of external and internal wood or metal coatings; perchlorvinyl varnishes - for protecting of various building constructions from aggressive environments. Bitumen varnishes are used for the anticorrosive coat of metallic details.

Also, bitumen-resin varnishes (solutions of bitumens and vegetable oils in the organic solvents) can be used for anticorrosive coat forming. Heat-resistance of such varnishes is no more than 50°C, the alkaliproof is also small. Paints for anticorrosive protection of metal products and structures can be obtained at their mixing with aluminium powder.

Ethylene varnishes and paints are made on the basis of divinyl acetylene polymer. They have high anticorrosive and painting qualities, ability to harden at a temperature to -25°C. Ethylene varnishes are relatively quickly deteriorated at the action of the light. A proof and economic paint can be obtained by mixing of ethylene varnish (60%) and red iron oxide (40%)

Nitrovarnishes are widely used for varnishing of metals and wooden products.

Paper coatings

Wallpapers are the roll finishing material with the printing pattern or embossing of different tones on single-color or multicolored background. They are applied for papering of walls and ceilings of dwellings and public buildings. Decorative coating of wallpapers can imitate the wood grain, fabric texture and surface of metal and other materials.

Wallpapers are made in the next types: paper, vinyl and textile on the paper basis and on basis of nonwoven composite materials.

Wallpapers are divided into 2 types: simplex-wallpapers (wallpapers, having one layer of paper) and duplex-wallpapers (wallpapers, consisting of two glued layers of paper).

Vinyl wallpapers are the paper basis with the vinyl coating of different density, which gives the strength and humidity resistance to the wallpapers. The vinyl wallpapers are used, as a rule, in apartments with enhanced hygienic requirements. It is possible to select 3 basic categories of the vinyl wallpapers, which differentiate a method of fabricating, by a density and surface appearance: foamed vinyl, flat vinyl, dense ("kitchen") vinyl.

Acrylic wallpapers are the analogue of the foamed vinyl wallpapers, but acrylic emulsion is putted on basis, in contrast to vinyl.

Textile wallpapers are paper linens, laminated with filaments of the natural or mixed fibers. Textile wallpapers have the enhanced heat-insulatinh and sound absorbing properties, light fastness. They belong to the group of nonflammable materials. Textile wallpapers on the basis of textile linens, which are glued on the foam-rubber, are produced also.

Velours wallpapers are paper linens, on which in the process of production a pattern is putted at first, and then velours naps. A soft velvet surface appears as a result. Textile and velours wallpapers are intended for pasting over of walls and ceilings of office, dwelling and administrative buildings.

Paper and vinyl wallpapers are made smooth and relief, embossed, structural and metallized. The last are laminated with a metallic layer on the basis of foil or metallized film.

The row of new types of wallpapers appeared at the last years. The special type of wallpapers is wallpapers for painting. They are produced on a paper and nonwoven composite materials bases, usually in the rolls of the large length and saturated with the special water-repelling composition. Wallpapers of this type allow reducing of requirements to the quality of wall preparation, possessing with an ability to vapour permeability. It is possible to repaint them with the dispersion paints to 5-15 times. Structural wallpapers are made from two layers of texture paper of white color, glued between them. The three-layered embossed wallpapers are also made with the additional layer of paper, giving the large inflexibility to the linen. The coarse fiber wallpapers consist of two layers of dense paper with the wood fibers between them (sawdust). The presence of sawdust provides a grainy texture of the coating. Wallpapers hold to 15 cycles of repainting. Glass fiber wallpapers have the glass fabric basis, which gives the high degree of fire-resistance, strength and elasticity to them.

Wallpapers are supplied in the rolls with edges or without them.

The stability of coloration to light, resistance to the abrasion, destroying effort in the wet state, whiteness, stability of embossing pattern, maintenance of harmful matters, isolated during the exploitation in to the an air, are standardized for the wallpapers. Wallpapers should not have mechanical damages of linen, wrinkles, folds, breaks of edge.

Symbolic notation of the wallpapers includes their type (paper, vinyl and textile wallpapers on the paper or no woven composite materials basis), useful width and length of linen in a roll, grade, resistance of coloring to the light, method of gluing and removal from base after gluing on (Fig. 18.3).

Lincrust is a variety of wallcoatings. This is a roll material with raised patterns, consisting of the mixture of synthetic polymers and filling agents on the paper basis.

Polyvinyl chloride decorative finishing film is a roll finishing material, made by a roller-calender method from vinyl chloride polymer, plasticizers, pigments and different admixtures. The films are produced with a glue layer on a reverse and without a glue layer.

A film surface can be smooth or stamped and multicolored with a printed pattern.

Date: 2015-12-18; view: 1256