Powder paints: types and properties

Epoxy Polyester Powder Paint

The structure of this type of paintwork materials consists of epoxy and polyester substances, which, interacting, form a solid film on the surface. Among all powder paints, epoxy-polyester is the palm. Such a choice of specialists in the paint and varnish industry is due to the following factors:

1. This paint turns less yellow, so it can be used to paint areas that are most exposed to heat and light, such as radiators, walls and ceilings;
2. Able to withstand maximum temperatures in the oven;
3. When applied correctly, once cured, the paint will provide virtually permanent use of the surface it was applied to. This is due to the fact that the coating is resistant to household chemicals, moisture, and is practically not subject to abrasion;
4. It is inert after hardening, therefore, it is absolutely non-toxic.

But there are no completely perfect things in the world. Absolutely everything has its drawbacks, including epoxy-polyester powder paint. Its disadvantages are as follows:

1. The correct application of this paint is subject only to a specialist. The average person who does not deal with epoxy-polyester paint every day, even with the proper equipment, may not be up to the task.
2. High price. Despite the fact that there is no overconsumption of material during painting, and exactly the amount of a helmet that is needed to cover the surface gets to the surface, the pleasure is not cheap. This is due to the fact that the paint and varnish material itself, as well as the equipment for its application, is very expensive, therefore, painting with this paint is far from a budget option.

Below is a table for testing epoxy powder coating

Below is a table for testing epoxy polyester powder coating

Thus, summing up, it is worth noting that polymer-powder epoxy paint, like any other paint and varnish material, has its advantages and disadvantages. However, the main purpose of using polymer powder paints is to obtain a hard and durable film resistant to chemicals, solvents, as well as to impacts, providing a sufficiently long service life of the coating.

Views

By composition, polyurethane paintwork materials can be divided into two groups:

• two-component products requiring mixing, since each component is produced in a separate container;
• one-component paints that do not require mixing - they can be used immediately after purchase and surface preparation, since all the main components are already present in the product.

One of the cans of the two-component composition contains the hardener, the second contains the resin. This variety is much stronger and more resistant to external negative factors affecting the surface. The product is captured without the participation of water vapor from the air, which greatly expands the range of use of the product.

Classification of one-component paints by type of base

To classify one-component paints, they can be divided into three categories:

• products based on organic compounds;
• alkyd-urethane agents;
• water-dispersion suspensions.

The composition of polyurethane compositions of the first category, in addition to the main elements, includes xylene or toluene. For dilution of such materials, specialized solvents are produced.The agent reaches the solid state due to the reaction of the components with moisture from the air. Therefore, the time required for complete drying of this type of paint will depend on the level of humidity in the room.

The second type contains an alkyd-urethane varnish. A distinctive feature of this paint is a very short drying time, usually it is one and a half hours. White spirit is additionally purchased as a solvent for alkyd-urethane products.

The latter type has a similar name due to the solvent that is used for these products - during the work, you will need ordinary water. Water-dispersion paints are odorless and harmless to humans; when painting the surface with such a composition, there is no need to use additional protective equipment. They are captured by the moisture in the air.

Powder and epoxy-polyurethane paints

One more type of polyurethane painting products can be distinguished - powder formulations. They are produced in the form of a homogenized mixture, the components of which are: pigments, hardener, polyester resin and filler.

This type belongs to thermosetting dyes. They process a product or base, after which they undergo heat treatment, as a result of which a reaction occurs between the components that are fused with each other. The result of such work is a durable and hard coating. That is why powder formulations are most often used for work in mechanical engineering.

Epoxy-polyurethane paint is highly durable, therefore it is used in industry for processing various kinds of structures that come into contact with an aggressive environment to provide them with a good level of protection.

Classification by application method

Also, polyurethane compounds can be divided into groups according to the method of application to the surface:

• aerosol products;
• paint that needs to be applied with a roller or brush.

The first group of paintwork materials is used for metal products and surfaces. Automotive polyurethane paint in spray cans forms a uniform coating, which is completely free of smudges and streaks.

Types of surfaces

The chemical industry has mastered the production of powder paints for application to non-metallic surfaces, including MDF. If the base of the coloring composition is epoxy, deviations from the standard staining method are absolutely unacceptable. Otherwise, color fastness and resistance to harmful weathering will be insufficient. But if all the requirements are met, the mechanical properties of the coating will be at the proper level. Unfortunately, epoxy paints can hardly be considered heat resistant.

If you need a finish that can be used outdoors and color fastness is critical, polyester paint is worth using. When significant amounts of acrylate compounds are introduced into the dye mixture, the surface will be resistant to contact with alkalis. Its appearance can be both matte and glossy. It is these powder paints that are widely in demand at machine-building plants.

The low-temperature variety of the dye mixture turns out to be more and more in demand from year to year, but so far the technologies have not yet been developed enough to gain massive popularity. Polyurethane grades are characterized by a stable gloss and are mostly used to paint parts that are constantly subject to friction or heavy wear. Their appearance is similar to silk, chemical inertness is very high. Such formulations are not afraid of any weather conditions, or automobile fuel, or mineral oil.

Plasticized PVC powder paints are soft like rubber.The cover layer is less susceptible to water, even with the addition of detergents, and remains presentable for a long time when applied to wire baskets in dishwashers. The carefully selected composition allows the paint to be used in contact with food and drugs.

If electrical insulating properties are needed first of all, polyvinyl butyral is used as a base. Paints created with its use can play both a protective and a decorative role. The coating is resistant not only to electric current, but also to gasoline and abrasion. Mixes of this kind are preferable for the interior decoration of industrial facilities.

The antistatic properties can be selected quite flexibly. Technologists influence them using various additives, providing for certain processing modes, as well as synthesizing film-forming agents with target parameters.

Epoxy-polyester paint is considered to be thermosetting and mechanically resistant at the same time. But remember that ultraviolet rays can damage it. The chemical industry has also mastered the production of fluorescent dyes. Therefore, the choice of products is huge, but you should carefully read the composition of the paint before buying.

Types and application

Unlike conventional paints, powder paints have a completely different principle of surface painting. Having electrical insulating properties, its particles are charged from an electric field, which differs from the surface that will be painted. Thus, getting on it, these tiny grains of sand simply stick to the surface. It is not possible to paint the surface well at a time, therefore this procedure is repeated twice. As soon as the surface has been covered with a layer of paint, it is imperative that high temperatures are applied to bake it.

Depending on the surface to be painted on, be it the outside or inside, and some other properties allow this material to be classified into two main groups:

• Thermoplastic;
• Thermosetting.

If we talk about the first option, then it is often used for painting metal and chrome products. After the paint has been applied to the surface, a special protective film is formed due to the heating of the material, and then its cooling. It is heat-resistant, if the mode of operation with it is observed correctly, otherwise the film will quickly dissolve.

Knowing the conditions in which the painted surface will be used, the following types of paint can be distinguished:

• Vinylite is the base, but it can be mixed with other additives and used for decorative purposes. The main element of the colorant is suitable for indoor use only. The thickness of the layer is small, but even so the level of protection is very serious.
• Polyvinyl chloride finds its application in working on the external and internal surfaces of objects. It is applied both outdoors and inside. PVC-based paints have a composition that is resistant to chemicals and weather conditions.
• The polyethylene composition has high performance in both physical and mechanical properties, which is why it is used for painting the pipeline.
• The paint with polyamide has good external characteristics and is used for decorative finishing of the premises outside and for all internal work.

If we talk about the second version of paints, then they form a film after drying. The composition of such a coating does not undergo any changes in the type of dissolution or melting, which means that the finished product will have characteristics that are resistant to various kinds of defects. Polyester and epoxy resins, polyurethane elements and acrylates are the basis of the composition.

The polymer-epoxy structure makes it possible to successfully use this type of paints in mechanical engineering. The antistatic function is inherent in polymer powder paints. In order to give the car an interesting look, you can add a luminescent pigment, this will make a fluorescent car paint.

Epoxy substances in the composition make it possible to achieve high mechanical strength of the painted surface. The only factor that can contribute to the appearance of defects is ultraviolet radiation. Only mirrored chrome can resist such factors. Polyester paint is precisely aimed at solving the problems of exposure to the sun, it does not react to its radiation. This coating can be used to decorate any external surfaces that will retain their color for a long time.

Epoxy-polyester paint contains polyester and epoxy blowing agents, which begin to react with each other during the curing process. These paints are almost non-yellowing and can withstand high temperatures.

The acrylate base is resistant to alkalis. The pigment, which is responsible for the color, can retain its properties for a long time. The dyes that are added to powder paint can be taken in a variety of ways, which is their uniqueness.

Surface preparation and application

Today the range of polymer paintwork materials is quite wide. Manufacturers offer polyurethane paints for concrete of various types. They differ not only in composition, but also in characteristics. For example, a thin-layer coating, which forms a polymer enamel, is characterized by increased wear resistance. Consequently, the requirements for the surfaces to be painted and the conditions for applying paintwork may differ. Therefore, you must follow the instructions that are on each bank. But it is better, even before the enamel is chosen for the floors, to find out what needs to be prepared for painting.

Requirements for surfaces

The following requirements are imposed on the surfaces to be painted:

• the surface must be free from dirt, splashes, dust, efflorescence, grease stains and drips of solution;
• its moisture content should not exceed 4%;
• old paintwork materials with poor adhesion must be removed;
• impregnations and sealants should be applied to waterproof small cracks;
• the appropriate primer is applied (polyurethane or acrylic primer).

Features of application and care

Before applying to the base, the paint must be properly prepared: stir, if necessary, remove the film and filter. To bring the paint into working condition, you need to tightly close the jar with a lid and turn it upside down. Shake and flip back. The temperature at the place of staining should be at least + 15 ° С and not higher than + 30 ° С. Air humidity at a temperature of 20 degrees should not exceed 85%.

The application of the paint composition can be done in one or in several layers. To obtain an even and smooth finish, polyurethane concrete floor paint is spread evenly using a roller or metal trowel with additional roller rolling. After laying the first layer, you must immediately start applying the second. Industrial concrete floors with a polyurethane surface require little maintenance. But still, it is worth avoiding spills of water and concentrated strong acids with prolonged exposure to the floor in the form of puddles.

General characteristics

Solid dispersed structures, in the combination of which there are film-forming resins, hardeners (driers), various pigments, as well as setting additives, are called powder paints.

Such compositions are inherent in:

• homogeneity (uniformity of composition);
• physical and chemical constancy;
• the immutability of the mixture during operation and storage.

Polyester powder paints are produced in the following way: all components are mixed, then homogenized, (this happens at a high temperature in a twin-screw extruder). The finished melt is cooled, crushed and sieved to achieve powder homogeneity. Such paints are used exclusively for metal surfaces. However, over the past decade, several types of powder coatings for plastic and wood have been created.

Such paints are distinguished by environmental safety, good protective properties, decorative effect. They are also economical. Coloring takes place in a special chamber, which achieves 100% use of the material.

Features of powder paint:

• decorativeness (the ability to use the widest color palette);
• reliability (high chemical resistance);
• the ability to get a fairly thick coating in one painting;
• complete absence of drips on verticals;
• good adhesion.

Composition

Paints containing polymer components necessarily also contain pigment; together with the polymer, the dye forms the basis of the coloring material. Other substances are also attached to the basic components, with the help of which the desired characteristics are provided. Acrylates are often added, special resins, with which the paint forms better films.

Additives can also be used to accelerate the curing of the coating, give it a variety of colors and improve the overall appearance. Compounds of titanium and aluminum with oxygen are taken as fillers.

The conclusion is simple: excellent properties of powder paint are achieved with a minimum hazard class (toxicity). People, pets and plants will not be affected at all when using these dyes.

All components of polyester paint have excellent flow properties, particles do not stick to one another and do not stick to various foreign objects. You do not need to use special additives to dissolve the composition.

The technical properties of powder paints are quite good, most often they are applied electrostatically. If it is necessary to guarantee mechanical strength and stability, you can use not only epoxy components, but also mirror chrome, which is less susceptible to ultraviolet light. Epoxy mixtures have operating temperatures from - 60 to 120 degrees, the initial dielectric parameters are very significant. Taking vinylite as a base, powder paint is obtained strictly for internal work, but it can withstand moisture at normal temperatures, and there is no need to form a thick layer.

Polyester-urethane blends are chemically formed by combining hydroxyl-containing polyesters with blocked polyisocyanates. The optimum operating temperature for forming the coating is approximately 170 degrees. The thickness of the layer to be created is strictly limited; it must correspond to the range from 25 to 27 microns. Polyester-urethane paint allows you to simultaneously achieve hardness, resistance to caustic substances, excellent resistance in all weather conditions. The surface retains its qualities under the influence of weak solutions of acid, mineral salts, hydrocarbons.

In practice, polyester-urethane powder paints are used for anticorrosive protection of sports and agricultural equipment, housings of air conditioners and other electrical apparatus, car parts and furniture. The widespread use of such coatings is possible due to the fact that they are not very dangerous. Note that it is impossible to paint the plastic with a powder method, because a heating of at least 150 degrees is a prerequisite.

A variety of powder paints

At first, thermoplastic paints were used, but in the past few decades, thermosetting paints have been used instead.This made the field of application of powder paints much wider due to the fact that they began to have much more unique properties, which are, first of all, resistance to mechanical damage and durability.

Powder paints are divided into:

1. Thermosetting powder paints (also called thermosets);
2. Thermoplastic powder paints.

The thermosetting group of powder paints is distinguished by the fact that during its heating, a chemical reaction occurs, as a result of which a strong solid film forms on the surface to be painted. And paints belonging to the thermoplastic group, when exposed to high temperatures, melt, and after cooling they acquire a solid structure. The latter have great plasticity.

Powder paints of the first group, depending on which film-forming substances are included in their composition, are divided into:

1. Epoxy powder paints;
2. Epoxy-polyester powder paints;
3. Polyester powder paints;
4. Acrylate;
5. Polyurethane.

Thus, the main film-formers in powder paint can be: epoxy, a mixture of epoxy and polyester, polyester, and acrylate. All paints in this group can be used when painting mechanical engineering parts, since they have much higher hardness, impact resistance, and decorative properties.

Of all the paints in this group, the very first epoxy powder paints appeared, the popularity of which is high even today. They are widely known for their basic properties, which are high strength, adhesion, and good resistance to solvents. However, epoxy powder paints have their drawbacks. These include:

1. Intolerance to exposure to high temperatures. For example, if they are very hot, the coating will take on a yellowish tint.
2. Intolerance to sunlight. When an epoxy powder coating is exposed to ultraviolet light, its top layer is susceptible to deterioration, resulting in a chalk-like coating. However, apart from the aesthetic appearance, this does not affect anything else, since the strength of the coating remains unchanged. Therefore, these paints are more used for painting interiors.

It should be said that absolutely any paint and varnish equipment is suitable for using this type of paint. In order for the applied powder coating to acquire a solid structure, it will take only 15 minutes and a temperature of 170C for conventional paints and 140C for fast-curing paints.

For clarity, you can watch the video on powder coating

Surface type

Surfaces treated with this paint can have a matte or glossy effect. The matte colorant contains scaly particles. The difference in the reaction characteristics of the impurity provides a matte appearance. It is mainly used in mechanical engineering.

The composition of the glossy paint contains various epoxy, polyester film formers. Also, it is based on the pigment necessary for the implementation of a certain color.

The glossy surface is characterized by high reflective properties, resistance to corrosion processes, which is important for the automotive industry.

Peculiarities

Powder paint was invented a long time ago, but right now it has gained the greatest popularity. Its peculiarity is that it is produced in the form of a powder and remains in this state even when applied to the surface. These characteristics allow it to obtain a number of benefits related to the environmental friendliness of the product. Unlike ordinary paint, there are no organic solvents here, so it is completely safe for humans.

The process of applying such material is carried out using special equipment, which allows you to work economically, without wasting more than necessary and without polluting the environment with elements that do not fall on the surface to be painted.

Considering the composition in more detail, you can find a hardener, a film-forming resin, a filler, a pigment and a target additive in it. The advantages of such paint are undeniable, and most importantly, when working with it there is no need to use a solvent, because the structure does not change its properties under any circumstances. The technical characteristics of this material make it possible to use it for painting a wide variety of surfaces, among which are:

• metal surfaces;
• household appliances (microwave ovens, refrigerators and more);
• sports equipment, equipment for athletes;
• furniture;
• lighting;
• glass and ceramic products;
• elements of machines.

The surfaces to be painted with powder paint can be very diverse. This type of staining is of particular importance in the case of staining pipes inside, which are under high pressure. This material can withstand high temperatures, so not every type of paint can be used for interior decoration.

Varieties

Powder paints based on thermosetting film-forming agents are widely used. They are divided into 2 types: polyester and epoxy-polyester.

Polyester compounds

They are based on a special fine powder, in which polyester, pigments and additives are used, but at the same time there are no solvents or epoxy resin.

Polyester paints are characterized by low toxicity, therefore they are used even for painting bicycles and car parts. They are designed for various metal surfaces that are regularly exposed to various atmospheric influences (high / low temperatures, snow, rain, hail, wind). Resistance to temperature changes is very high. Application methods - electrostatic or tribostatic methods.

Other positive characteristics include:

• excellent filling and hiding power;
• resistance to aggressive chemicals;
• fast drying.

Advice! Store paint and varnish for no more than 12 months at a temperature of 25 ° C.

Epoxy-polyester

These paints are based on polyester (up to 50 - 70% of the total composition) and epoxy resins, supplemented with a hardener, fillers and pigments (up to 35 - 50% of the total composition). They belong to powder enamels for internal use and have high strength characteristics:

• impact resistance;
• elasticity;
• resistance to solvents;
• good flowability.

Epoxy-polyester (hybrid) paints are used to color and improve the appearance of metal products used indoors. This could be:

• electrical equipment;
• Appliances;
• dishes;
• Furniture for home and office;
• accessories for cars;
• heating devices;
• tourist supplies.

Staining methods: electrostatic or tribostatic. Epoxy-polyester compounds perfectly protect against corrosion, do not turn yellow when exposed to high temperatures.

Advice! When working with such enamels, be careful - wear a protective mask, special goggles and gloves

What else to consider?

To buy what you really need, it is worth considering a number of factors. An important role is played by the conditions in which the painting will be carried out, the type of surface, the color of the coating. When choosing a material, care must be taken that external factors (for example, cold) do not affect durability and performance during the dyeing process.

When making a purchase in a store, it is worth choosing between several varieties.In order not to doubt the choice, it is worthwhile to first study the information about each paint by scrolling through the reviews on the construction forums. This will allow you to better familiarize yourself with the quality indicators of the material. You should not take the first thing that you like on the store counter: the art of selling is to put the material that needs to be sold in a profitable place.

The powder coating process can be seen below.

Peculiarities

Powder paint has a number of positive aspects and is becoming a popular alternative to traditional painting methods. The main working reagent here is dispersion mixtures of various substances, more precisely, solid particles. The elimination of the solvent from the paint composition gives it such advantages as complete environmental friendliness and zero risk of fire.

By changing the type of pigment and its concentration, the manufacturer can influence the adhesion level, flow rate and susceptibility to static electricity. The pigments in the powder product are the same as in cans or cans of liquid mixtures.