- Water-based paint – history
- Composition of water-based paint
- Technology for the production of water-based paint
- Dependence of the characteristics of water-based paint on the binder polymer in their composition
- Characteristics of water-dispersed paints
- How to choose a water-based paint
- In conclusion – recommendations for painting work
In this Article: The History of Water Based Paint composition of water-dispersed paint; production technology; types and characteristics of polymers used in the production of water-based paints; performance characteristics of high pressure paints; how to choose a water-dispersible paint; recommendations for use.
At all times, a person wants his house to look neat and attractive. For this, regular cosmetic and major repairs are carried out, during which a fresh coat of paint is necessarily applied to the ceiling and walls. And among all existing types of paints and varnishes for the interior and exterior decoration of the house, water-based paint is in the lead, with which it is easy to work and which does not leave an unpleasant odor in rooms, typical for working with other paints and varnishes.
Water-based paint – history
As in the case of a number of modern building materials, two large-scale wars of the last century unwittingly contributed to the appearance of water-dispersion paints – the destroyed cities had to be restored, but the usual building materials were not enough, and they were expensive.
The history of water-based paints began with the discovery by the German chemist Fritz Klatte in 1912 of polyvinyl acetate, better known to us as PVA glue. PVA dispersion became the basis for the first water-dispersion paints that appeared in the 1920s..
German chemist Fritz Klatte
At the end of the 30s of the last century, synthetic rubber or styrene-butadiene was created in Germany, which became the second type of dispersion for water-based paints..
The last of the existing dispersions is acrylic, and paints based on it were originally developed for artwork. The first acrylic water-based paints were created in 1946-1949 and launched in the early 50s under the brand name “Magna paint” by American artists Sam Golden and Leonard Bock. True, the paints of this brand were intended only for artists, were packed in small tubes and dissolved not with water, but with turpentine or white alcohol. Boku created and released completely water-soluble acrylic paint in 1960.
Butadiene-styrene and acrylic water-based paints came to the construction markets of the post-Soviet states in the 90s from abroad – in the USSR, only paints based on polyvinyl acetate were produced and only for industrial needs.
Composition of water-based paint
In terms of its basic composition, it is formed by the smallest particles of polymers suspended in an aqueous medium. In addition, water-based dispersion paint, depending on the brand and manufacturer, can contain about 10-15 different additives, including: anti-freezing antifreezes; defoamers to reduce foaming; antiseptics (biocides); corrosion inhibitors; thickeners; additives that increase structural viscosity; preservatives; dispersants; plasticizers, etc..
As a percentage by weight, the composition of the water-based paint is as follows: 50% – a film former dissolved in water (50-60% aqueous dispersion); 37% – fillers and pigments; 7% – plasticizer; 6% – other additives.
Let’s take a closer look at the components. Depending on the purpose of the paint, the film-former (copolymer) in its composition will be polyvinyl acetate, styrene-butadiene, styrene-acrylate, acrylate or versatate dispersions. The role of white pigment is played by titanium dioxide, zinc oxide, in the case of water-based paints of the lower price range – chalk. The filler is chalk, calcite, barite, talc, mica, most often several different minerals are used simultaneously as a filler. The solvent in water-dispersed paints is demineralized (purified from mineral salts) water. I would like to note one of the components of such paints – a thickener, the role of which is most often played by carboxymethyl cellulose, which is also CMC glue.
Technology for the production of water-based paint
The process of creating a water-dispersion paint consists of the following stages: connection and mixing of an aqueous solution of a polymer dispersion with a filler and a pigment; dispersing the resulting pigment paste; introduction of a number of additives that bring the paint composition to the TU standard; filtration and packaging of the finished product.
Dispersion is a process in which liquids or solids are finely ground. Suspensions, powders, aerosols and emulsions are obtained by dispersion..
Mixing and dispersion of components of water-based paints is carried out in bead and ball mills (dispersants). Grinding takes place in a horizontal or vertical working chamber of the mill, inside which there is a shaft with disks that accelerate metal beads (up to 4 mm in diameter) or balls (from 30 mm in diameter) made of steel, aluminum oxides and zirconium. The more intense the dispersion, the higher the hardness and specific gravity of the metal balls..
The pigment paste obtained as a result of dispersion is placed in a dissolver. In its torus-shaped container, a frame mixer is installed, the rotation of which prevents thick and sticky components from settling on the walls and bottom of the dissolver, and the composition of the water-based paint is brought to standard characteristics.
The timing of mixing the components of water-dispersed paint depends on the volume of the mixture, the initial characteristics of the components to be placed, the power of the dispersant and dissolver – as a rule, 20-30 minutes is enough for each of the operations.
At the final stage, the finished paint is passed through mesh filters and poured into containers. The entire cycle of work on the production of paint must take place at an air temperature of at least +5 ° C.
Dependence of the characteristics of water-based paint on the binder polymer in their composition
Today’s water-based paints contain one of five types of binder, which impart both positive qualities and disadvantages to the water-based paint:
- polyvinyl acetate, paint marking “VD-VA”. In terms of their quality, paints with this polymer binder are of the lowest quality – they turn yellow over time, a dense, opaque film forms on the surface, the applied paint layer is not waterproof. Weak characteristics do not justify the low price, such paints have only narrowly targeted use;
- butadiene-styrene, paint marking “VD-KCH”. Possessing good water resistance and low price, water-based paints based on this binder, as well as on PVA, form an excessively dense surface film and are not resistant to sunlight. Paint brand “VD-KCH” can only be used for interior work;
- styrene-acrylate, paint marking “VD-AK”. In terms of quality characteristics, paints on this polymer are much better than those described above, they can be applied to both external and internal surfaces. The coating formed by them is porous and, accordingly, vapor-permeable, resistant to the effects of solar radiation and atmospheric phenomena. The small size of polymer particles, not exceeding 0.15 microns, provides high-quality adhesion to almost any surface, penetration into porous surfaces, which increases their strength;
- acrylate, marking of paint “VD-AK”. This polymer is more expensive than styrene-acrylate, has higher quality characteristics in all respects – a tougher coating gives high resistance to solar ultraviolet radiation. Such paints are widely used in facade works and for application to wooden surfaces;
- versatat, paint marking “VD-AK”. Polymer versatate is used in the composition of water-based paints not so long ago, the quality of the coating on this binder is not inferior to acrylic paints, while their price is lower and approximately corresponds to the cost of paints on styrene-acrylate binder.
Characteristics of water-dispersed paints
Depending on the type and amount of polymer binder, these paints have the following positive qualities:
- do not contain toxic components, practically odorless;
- easily applied to surfaces, diluted with water;
- able to bridge cracks up to 1 mm wide;
- not flammable;
- resistant to moisture (washout resistance);
- elastic and durable, no chalking;
- resistant to ultraviolet and atmospheric phenomena;
- resistant to wear;
- just tint in any color shade;
- random drops of paint can be easily removed with a damp cloth;
- vapor permeable, which means that colonies of fungus and mold will not appear;
- resistant to alkalis;
- have high adhesion (tight fit) to the base;
- retain color, shine and yellowing resistance;
- dry quickly, usually in 40 minutes;
- a layer of water-based paint on the surfaces painted with them will last about 10-15 years.
Negative qualities of water-based paints, in comparison with alkyd and oil paints:
- storage and painting work can only be performed at temperatures above +5aboutC. Painting at lower temperatures will result in uneven paint distribution and take a long time to dry. If during storage the paint has gone through a cycle of freezing and thawing, its quality characteristics will be completely lost;
- for painting external surfaces and surfaces of wet rooms, you can use only expensive water-dispersed paints, on an acrylate and verstat binder;
- high cost, exceeding the price of organically thinned paintwork materials by 10-15% – manufacturers explain this by the complex composition of the paint. On the other hand, it is much easier to clean the room after painting the AK VD, because no need to wipe the stains with a rag with an unpleasant smelling solvent;
- before painting wooden surfaces with water-based paints, they must be thoroughly prepared – applying the first layer, drying it completely, then thorough sanding and a new layer of paint, re-sanding. The fact is that the surface tension of the water-dispersed paint layer is much higher than that of other paintwork materials – the wood pile will be raised.
How to choose a water-based paint
Application area.Water-dispersed paints are specialized according to the requirements for painted surfaces – for indoor and outdoor work, for dry and wet rooms. Accordingly, paint for interior work on external surfaces or paint for dry rooms on surfaces in damp ones can be applied, but it will peel off after a few months, because it contains a smaller amount of a film former and protective additives.
Appearance. Water-based paints are produced, giving a matte, glossy and silky-matte finish. Matt and silky matt paints are great for ceilings and wallpaper, but unlike glossy surfaces, they are less abrasion resistant – they cannot be washed frequently.
Colour. Water-dispersed paints, most often, are white – to obtain the desired color scheme, they need to be tinted. Jars of color schemes and color tables created by the color scheme are present in every hardware store..
Quality indicators in appearance:
- chromaticity. Open a can of paint, visually assess the degree of its whiteness – if the manufacturer used high-quality and expensive titanium dioxide, then the color will be exclusively white, without any shades;
- hiding power. The consumption of paint and the number of layers that must be applied to the surface to bring them into proper form depend on it. This indicator depends on the percentage and quality of the pigment, the density and density of the paint. There are two ways to reduce the cost of production of water-based paint, popular among small manufacturers – 1) add water, lowering the density of the emulsion, 2) introduce more inexpensive filler, while increasing the density. It is possible to estimate the covering power without a test painting if you weigh a 10-liter jar with water-dispersed paint – on average, its density should be 1.5 kg / l, i.e. high-quality paint in a 10-liter container will weigh about 15 kg (“+” or “-” 1 kg).
Marking on the paint can. Water-based paint is marked with the letters “VD”, which means “water-dispersed”, then the letter designation of the polymer, for example, “KCh” or butadiene-styrene. Then the numbers follow – the first means the area of application of this paint, if it is “1”, then “for external work”, if “2”, then “for internal”. The numbers following the first are part numbers – we don’t need them. Make sure that there is an inscription on compliance with the conditions of GOST 28196-89, if instead TU is given – the quality of the paint may be low.
Manufacturer. On the local market, you will find a significant range of water-based paints from both domestic and foreign manufacturers. You can judge the quality of a particular brand by the reviews of your friends who have already used it in repairs and by the age of the given manufacturing company – if it is younger than 3 years old, it is better not to mess with its products. The fact is that the production of water-dispersed paints does not require any particularly large-scale production – by and large, only a dispersant and a dissolver are required. Therefore, they can be produced by any more or less sensible “small entrepreneur”, most often making up paint “by eye” and having neither a laboratory nor a technologist in his staff. The larger the manufacturing company, the wider the range of its products, the better the product itself will be.
Price.It cannot be less than one $ 1 (US) per liter in any way – if you are offered paint at a lower price, then it is of poor quality. The cost of water-based paint is determined not by the territorial location of manufacturers’ factories and not by labor costs, but by the current price of the components that are included in its composition. Almost all world manufacturers of high-quality pigments and polymers are located in Europe, so the cost of a good water-dispersed paint will be almost the same in Europe and in Russia – Russian manufacturers pay rather high customs duties for the import of raw materials for the production of water-based paint from abroad. But the real reasons for the low cost are cheap raw materials and violation of technology during production.
In conclusion – recommendations for painting work
Before starting work on painting the surface with water-based paint, it is necessary to prepare: previously painted to clean from dirt and dust, sequentially washing it with water, washing powder and clean water; cleaned with chalk and lime layers of old paint; smoothen unevenness with a putty, after which dry, sand and clean the surfaces from dust.
If painting work is carried out in the cold season, then the can with paint must be kept indoors for at least 24 hours, then opened, remove all visible inclusions and films, mix thoroughly and add, when painting with a spray, 10% water. The paint consumption is indicated by the manufacturer on the container, on average it will be 150-250 g / m2 with a two-layer application. After calculating the approximate consumption, tint the paint – it is necessary to tint 10% more volume than that which you calculated according to the average paint consumption. Reasons: the consumption will be higher in any case, and you will not be able to “get into color” when trying to tint a new portion of paint – the color tone will be at least slightly, but different.
To reduce the consumption of water-based paint will help the preliminary application of a layer of primer to the painted surface – it is much cheaper than paint.