What is the difference between powder and polymer coating of steel?

To protect steel, two main types of coating are used – powder and polymer. They are applied to the metal after galvanizing. Polymer coating of steel is a liquid paint and varnish material that is applied by pouring/spraying paint onto the metal using special equipment. These include Professional RAL and RALplus coatings.

Powder coating of steel is also a polymer, but has a different chemical composition and is applied by spraying dry powder paint. It attaches to metal through electrostatic attraction, like a magnet. Through heat treatment, the powder is polymerized - transformed into a single uniform surface. Powder materials include: Steel silk, Steel velvet, Polyester, Ruukki, Polyurethane, Pural.

Structure of steel sheet with polymer coating

Applying polymer coatings to galvanized steel is a complex process, since a steel sheet with a polymer coating has a multilayer structure: a steel sheet, a zinc layer, a passivation layer, a layer of soil, on the front side there is a layer of colored polymer, and on the bottom side of the sheet there is a “multilayer pie” Complete with protective paint.

The basis for production is rolled steel with a thickness of 0.4-2.0 mm. A layer of zinc (or aluminum-zinc) can be applied to it either by galvanic method or by immersion in the melt. Sometimes a polymer coating is applied directly to ferrous metal (however, such metal sheets are very short-lived). Then the metal is passivated, primed and covered with a protective layer of various polymers.

Where are polymer metals used?

Areas of application:

• shipbuilding;
• mechanical engineering;
• assembly of various equipment.

Metal structures are made from individual parts that will be installed in water or places with high humidity levels.

Polymer metal in mechanical engineering (Instagram / bazz_linser)

Methods of applying polymer coating

Polymer coating is obtained by various methods:

• by applying a pre-made film to the strip,
• immersing the strip in the polymer melt,
• roller method of applying liquid polymer (Coil Coating),
• spraying polymer in powder form using the electrostatic method.

The coating can be either one-sided or two-sided. Rolled products with one-sided polymer coating are rolled products with a two-layer polymer coating on the front side and a single-layer polymer coating on the back side.

Two-layer polymer coating – a coating consisting of a layer of primer and a layer of finishing polymer.

A single-layer coating is, as a rule, a coating on the back side of rolled products, consisting of a layer of protective enamel without regulatory requirements for appearance, thickness, corrosion resistance, etc.

Application of a polymer coating is the final stage of rolled metal production. At the customer's request, a protective film of polyethylene can be applied.

Thus, most often polymer-coated steel has the following structure.

1 - steel sheet

2 - zinc layer

3 — passivating layer (anti-corrosion layer)

4 - layer of soil

5 - polymer coating

6 - protective paint on the back side

The primer layer is designed to provide strong adhesion and high corrosion resistance of the entire system, i.e. The quality of the primer determines how firmly the polymer coating will adhere.

Advantages and disadvantages of powder coating

Due to the peculiarities of production technology, powder-coated steel has a greater coating thickness than sheets with a polymer layer. This increases anti-corrosion properties.

Types of polymer coatings for steel sheets

The following are used as polymer coatings:

• polyester (polyester), designated PE. SP;
• food laminate;
• matte polyester, modified with Teflon, PEMA;
• pural - polyurethane modified with polyamide, PURAL;
• polyvinyl chloride plastisol, PVS;
• polyvinylidene fluoride, PVDF, consists of 80% polyvinyl chloride and 20% acrylic;
• acrylic, AY.

Polyester is the most popular coating due to its optimal price-quality ratio and has satisfactory resistance to UV radiation and corrosion. However, resistance to mechanical damage is higher for Pural and PVDF coatings.

Pural is more expensive than polyester, but it also has higher chemical resistance, as well as to mechanical stress and temperature changes.

The most resistant to mechanical damage due to its thickness, but at the same time the least resistant to temperature changes and UV radiation is plastisol .

The most durable and most expensive coating is polyvinylidene fluoride (PVDF) .

The least durable and unstable to mechanical and atmospheric influences is acrylic coating.

All these coatings can have different texture, shine, and colors. Thus, polymer coatings have different resistance to ultraviolet radiation, high and low temperatures, atmospheric influences, mechanical damage and others.

The above coatings are initially liquid and are applied using the roller method, which is the most common and in demand both in Russia and in other countries.

The most important requirements for coatings are strong adhesion (adhesion) of individual layers to each other, the bottom layer to the substrate, hardness, bending and impact strength, wear resistance, moisture resistance, weather resistance, a set of decorative properties (transparency or hiding power, color, gloss level, pattern and etc.).

The anti-corrosion protective properties of coatings for internal use are classified in accordance with the EU standard 10169:2008. The wet chamber testing process is regulated by EN 13523-26.

TYPES OF COATINGS

The company offers polymer-coated rolls of various types:

• TWEED50 is a 50-micron polyurethane coating that has a velvety-matte structure and provides a 25-year guarantee of trouble-free roof operation;
• TIAR35 is a 35 micron thick semi-gloss polyurethane coating with a 20-year service guarantee. TIAR35 is a premium quality polyurethane coating at an affordable price;
• KEVAR – matte polyester coating with a thickness of 30 microns, provides natural color rendering, protects the material from ultraviolet radiation and the adverse effects of external factors;
• SKARDEX is an innovative high-quality polyester coating of 25 microns, which contributes to the long service life of roofing materials due to increased resistance to wear and abrasion;
• SKARDEX cupro is a glossy coating in the color of noble copper with a thickness of 28 microns, which will add unique elegance and exclusivity to your roof;
• SKARDEX matt is a matte polyester coating with a thickness of 30 microns, which is reinforced with polyester resins and is resistant to mechanical stress and UV radiation. The structure of the coating imitates the natural properties of lotus and has excellent self-cleaning qualities when washed by heavy rains;
• SteelArt - in addition to the attractive design of the coating, it also has a multi-layer structure, which ensures the material’s resistance to corrosion, ultraviolet radiation, and mechanical stress;
• Coral is an environmentally friendly matte coating produced by NLMK based on polyester, which helps protect materials from ultraviolet radiation, precipitation, and mechanical damage.

The price of metal in polymer-coated rolls depends on the type of coating, the thickness of the metal, the amount of zinc per square meter and the volume of purchase. Delivery is carried out in Moscow and regions of the Russian Federation.

Cink Steel

Galvanized steel is rolled products made from different grades of steel. The surface of the material is covered with a zinc layer with microscopic dimensions. This is done on both one and two sides of galvanized steel. Galvanized steel, despite its fusibility and softness, is resistant to corrosion. This ability persists in both dry and humid climates. The action is possible due to the rapid formation of a protective film on the surface of galvanized steel of less than one millimeter. Thus, the lower layers of galvanized steel are effectively protected from destructuring, destruction due to salts, humidity, acids and other aggressive environments.

Application of galvanized steel

Galvanized steel is widely used in the shipbuilding, aircraft, food and medical industries. Galvanized steel has found particular popularity as a roofing material, as well as as a base in the process of producing corrugated sheets. Depending on the brand, galvanized steel has the following purposes:

• 01 - galvanized steel, intended for the manufacture of products of flat configurations;
• 02 - galvanized steel, intended for manufacturing by bending, fastening dishes and household utensils into a lock;
• 03 - galvanized steel, intended for the manufacture of stamped complex configurations of products using the deep drawing method;
• 04, 05, 06 - galvanized steel, intended for the production of stamping products using complex, especially and very complex hoods;
• 07 - galvanized steel, intended for the production of stamping products using the ultra-deep drawing method.

Advantages and disadvantages of galvanized sheeting

Among the advantages of galvanized corrugated sheets, the following should be highlighted:

• Good corrosion protection properties.
• Durable protective coating.
• Relatively low price - cheaper than painted ones.

Galvanization ensures high resistance of the product to rust. The material retains these properties throughout the entire warranty period. To maintain rust resistance, proper operating conditions must be provided.

Sheets are galvanized using the electrolytic method. It allows the zinc to firmly adhere to the metal. Under mechanical, shock loads and surface deformation, the risk of damage to the protective coating is small.

Due to the absence of the need to paint the original sheet with expensive paints and varnishes, production costs are lower. This also explains the cheaper cost of galvanized corrugated sheets in Moscow.

The disadvantages of galvanized corrugated sheets can be identified as follows:

• low decorativeness;
• less resistance to aggressive environments;
• relatively short service life - from 10 to 15 years.

Application of a polymer layer

The polymer layer is applied using special equipment in industrial chambers.

Polymer application conditions

Features of the work:

1. The humidity level in the treatment area should not exceed 60%.
2. Work must be carried out in a sealed chamber.
3. It is necessary to clear the work area of ​​foreign objects in advance.
4. The part must be secured.

Do not apply a protective coating outdoors, in dirty rooms with a lot of dust and debris.

Metal preparation

To increase the adhesion of plastic to metal, surfaces must be properly prepared. They need to be cleaned of dirt and wiped with a solvent to remove grease stains. Treatments to remove plaque can be done chemically, thermally or mechanically. It is important to make the surfaces smooth and remove dirt.

Mixing and applying the polymer composition

The polymer composition can be mixed with callers to change color. Coating:

1. The lighting in the sealed chamber is turned on. The master dresses in a chemical protection suit.
2. The parts are hung on hooks or clamped in special fasteners.
3. A negative cable, called ground, is hung on the workpieces.
4. The camera with the master closes, he applies paint.

The application process should be slow. It is important to apply the coating evenly over the surfaces to avoid unevenness.

Application of polymer coating (Instagram / ilber.aktobe)

Thermal stabilization of polymer metal

After applying the paint, the part is slowly heated to change the properties and characteristics of the material. The workpieces are immersed in a special chamber, which is heated to 200°C. The duration of thermal stabilization is 60 minutes. After this, you need to turn off the oven and leave it to cool to 100°C. When it cools down, you can open the chamber. If you try to cool the parts forcibly, the protective layer will crack.

Polyurethane based coatings

Polyurethane gives products a number of exceptional properties that are unattainable for other polymers:

• increased hardness, which allows the use of polyurethane for products operating under particularly strong mechanical loads, for example, for bending steel;
• high wear resistance and abrasive resistance, for example, injection molded polyurethanes are several times superior to rubber, plastics and metals in their abrasive resistance;
• With increased hardness, polyurethane retains high elasticity, so the material is exceptionally durable.

Polyurethane coating is used for products that must have a long service life. It has excellent weather resistance, increased corrosion resistance and formability.

Material characteristics from different manufacturers:

Ruukki Pural

(Pural) – coating based on polyurethane resin.
Pural
coating was developed by the Ruukki concern and is a registered trademark of Ruukki.

The satin surface of this coating retains its color regardless of the angle of light reflection. Pural

was the first polyurethane-based coating on the market.

Coating thickness - 50 microns; zinc coating - 275 g/m2; metal thickness from 0.5 mm; RC5; RUV4; resistance to mechanical damage - ≥4000 g; guarantee up to 50 years.

Grand Line Quartz

(Quartzite) - a thick organic coating (55 microns) based on polyurethane modified with polyamide granules, the reverse side of the material has a similar color (twincolor).

Quarzit

It is distinguished by its versatility of use due to its high performance characteristics:

the coating has polyamide granules; coating thickness - 55 microns; zinc-aluminum protective metal layer - ZA 265 g/m2; metal thickness 0.5 mm; high corrosion resistance; RUV4; resistance to mechanical damage - 2H; warranty up to 35 years.

Grand Line Quarzit Lite

(Quartzite Light) - coating with polyamide granules; coating thickness - 25 microns; zinc-aluminum protective metal layer - ZA 265 g/m2; metal thickness 0.5 mm; high corrosion resistance; RUV3; resistance to mechanical damage - 2H; 30 year warranty.

Grand Line PurPur

(PurPur) is a Russian polyurethane coating modified with polyamide granules. PurPur™ is made on the basis of 0.5 mm Russian-made steel. Coating thickness - 50 microns; zinc coating - 275 g/m2; RC - no data available; RUV - no data available; resistance to mechanical damage -2H; 25 year warranty.

Grand Line Granite HDX

— low-structure surface; coating thickness - 50 microns; zinc coating - 275 g/m2; metal thickness 0.5 mm; RC - excellent; RUV4; resistance to mechanical damage -2H; warranty up to 35 years.

Metal Profile Prisma

- one of the polymer coatings from the English plant Corus. The material has all the advantages of polyurethane, but differs in a layer of zinc and aluminum alloy. The peculiarity of the composition provides excellent anti-corrosion properties and high resistance to mechanical damage.

Colorcoart Prisma is available in the most popular colors as well as metallic colors. Coating thickness - 50 microns; zinc coating - 220 g/m2; metal thickness 0.5 mm; RC-high; RUV - high; resistance to mechanical damage - high; 20 year warranty.

Metal Profile Puretan

— coating thickness — 35 microns; zinc coating - 275 g/m2; metal thickness 0.5 mm; RC - high; RUV - high; resistance to mechanical damage - high; 12 year warranty.

Metal Profile PUR 50

— coating thickness — 35 microns; zinc coating - 275 g/m2; metal thickness 0.5mm; RC - high; RUV - high; resistance to mechanical damage - high; 40 year warranty.

Grand Line Polydexter

(Polydexter) is a semi-matte coating based on polyester with polyamide granules.

This coating is classified in the polyurethane group due to the fact that the steel is coated with Polydexter. Thickness 0.5 mm; zinc layer 275 g/m2; has polyurethane primer on both sides. The reverse side is a two-layer polyester coating in beige color RAL1015.

Coating thickness - 25-27 microns; RC - excellent; RUV4; resistance to mechanical damage - H-2H; 20 year warranty.

Matte Polyurethane

It can be very diverse: matte with small or large crumbs, embossed or copying a variety of natural materials. Matte Polyurethane has similar characteristics to glossy, but has a less shiny and more silky surface.

Material characteristics from different manufacturers:

Ruukki Pural Matt

(Matte Pural) - has all the advantages of the Pural coating based on polyurethane, but has a more structured surface, similar to natural silk. The slippery surface of the coating is resistant to dirt. Coating thickness - 50 microns; zinc coating - 275 g/m2; metal thickness 0.5 mm; RC5; RUV4; resistance to mechanical damage - ≥4000 g; 50 year warranty.

Grand Line Quarzit Matt

— textured polyurethane coating, reverse side in the color of the front coating (twincolor).

Coating thickness - 50 microns; zinc-aluminum protective metal layer - ZA 265 g/m2; metal thickness 0.5mm; RC - excellent; RUV4; resistance to mechanical damage - H; warranty up to 35 years.

Recommendations for working with polymer metal

Tips for using polymer coatings for metal:

1. Before applying the polymer, you need to prepare the working chamber - install effective lighting, remove unnecessary objects.
2. When carrying out work, you must use a chemical protective suit, a breathing mask, and safety glasses.
3. Coating is repeated 3 times.

You can paint several parts at the same time, but this requires a spacious painting booth and a furnace for thermal stabilization.

The polymer layer on the metal reliably protects the material from the formation of rust, levels the surfaces, and makes them stronger. The effect depends on the correct preparation of the working surfaces and the application of the polymer layer.