Coating and colour. Thermocolour.
Steel is a basic constructive material all over the world. A great amount of trade marks satisfy practically any demands. But use of rolled steel without anticorrosive covering for making sandwich panels is not effective. A zinc covering is used as the most effective protection. Zinc together with iron creates a galvanic pair and till there is zinc on the surface of the material the steel does not acidified.
For increasing of the period of anticorrosive protection of the steel and for improving the appearance the metal surface we use passivating composition and special polymeric coatings. Passivating compositions may be both chromic and non-chromic. They are put in view of water solution on the zinc surface and then they enter into a chemical reaction with a zinc layer.
Finish decorative and protective characteristics of Thermopanel are achieved with the help of special polymeric coatings. An application of a decorative protective covering to a hot-galvanized rolled steel is made by the method of Coil Coating – this is a successive putting of layers passivation, the soil, enamel and varnish by the roller method with the next drying in the stove.
The structure of a decorative protective covering
A decorative protective covering of a hot-galvanized rolled steel used in the Thermopanel has a very complicated multilayered structure, where the destination and characteristics of each layer depend on the demands to the final product. In details the structure looks like that:
- a steel sheet
- a zinc covering laid on by the hot method – the basic anticorrosive layer with thickness from 12 to 26 mkm
- passivation – a conversion layer, protecting from appearance of “white rust” on the zinc covering even after a mechanical damage of a varnish-and-paint layer. The passivation layer thickness is to 0,5 mkm
- soil – a layer which provide safe adhesion of enamel with a zinc covering. The layer thickness is 5-8 mkm
- enamel – basic polymeric decorative layer which protects the surface from the influence of external factors: moisture, mechanical damage, ultraviolet rays, interference of aggressive gas. The layer thickness is from 20 to 200 mkm (depends on the enamel kind)
- varnish (on some kids of coverings) – is used for additional protective and decorative characteristics of the front surface. The layer thickness is 20 mkm.
Protective-decorative material's kinds
Different polymeric coverings provide durability of the material and are characterized by resistance to ultraviolet rays, to temperature (till 120 °С), aggressive environments, mechanical damages, to corrosion and other factors. Polymeric coverings may be of different kinds. The basic of them are polyether and polyurethane. The choice of polymeric covering depends on a building function and conditions of panel's usage.
Polyether is the most widespread among the polymeric coverings. This is a rather cheap covering with glazed or matted covering which can be used under different climate conditions. The base of the covering is polyester resin which is highly resistant to ultraviolet rays.
The material has high level of flexibility and compactibility, but and the same time a very strong and hard film. The level of shine can vary from matted to glazed. Polyether covering has an optimal balance of characteristics and economy. Polyether is the best balance of price, quality and high customer features for rolled zinc of building purpose.
Technical Characteristics of Polyether
| Covering quality characteristics name | Methods of examination | Polyether covering quality characteristics |
|---|---|---|
| Adhesion (linkage strength) | ГОСТ 15140-78 | Not more than 1 point |
| Strength under back strike | ГОСТ 4765-73 | 50-100 кГс см |
| Elasticity by Ericsen | ЕССА Т6 | Not less than 6 мм |
| Elasticity under T-curve | ГОСТ 30246-94 | Not more than 2Т |
| Hardness by a pencil | ЕССА Т4 | F-H-2H |
| Glance 600 | ЕССА Т2 | 30-40% |
| Resistance to solvent abrasion, МЭК | — | More than 100 times |
| Whetherability | ЕССА Т8 | Not less than 500 hours |
A Smooth Polyether Covering (smooth polyether)
Polyether covering for external wall and roofing building constructions, internal rooms, for buildings and constructions for food, refining industry. The covering meets the requirements of industrial hygiene, high requirements of appearance, physical-mechanical characteristics, chemical resistance and durability.
Peculiarities of the covering:
- dry film thickness is 20-25 mkm
- optimal elasticity under low temperatures
- optimal hardness
- unlimited color scheme
- an opportunity to get a decorative covering with «metallic» varnish with high thickness of cover
- resistance to profiling
- service life before repair painting under usual conditions is more than 10 years
A Texturized Polyether Covering (texturized polyether)
A front covering on the base of polyether resin is used for external enclosing structures. The product is modified by polyacrylic fragments and has texturized external surface.
Peculiarities of the covering:
- higher resistance to different climate factors in comparison with polyether covering
- standard polyether covering
- texturized covering is more elastic when curving, elasticity by Ericsen, strength under back strike in comparison with standard polyether covering
- high resistance to abrasive attrition reduces the level of defectiveness during transportation, recycling and mounting of metal with covering
- surface of the covering prevent from slipping and that is undoubtedly an advantage while mounting
- service life before repair painting under usual conditions is more than 10 years
«Satin» Polyether Covering (satin polyether)
This is an upper covering on the base of polyether which possesses very good rheologic and elastic features and which has a front surface looking like satin. The product has high resistance to different climate conditions and provide a good protection from corrosion.
Peculiarities of the covering:
- while using the thickness of a dry film is from 20 mkm to 25 mkm
- a good balance between elasticity hardness
- unique matted «non-metallic» appearance
- high elasticity by Ericsen, strength under back strike
- service life before repair painting under usual conditions is more than 10 years
Polyurethane upper covering (polyurethane)
Polyurethane – is polymeric covering on the base of polyurethane resin. The covering is worked out for making external enclosing structures.
Peculiarities of the covering:
- the product is modified by polyamide particles and has texturized front surface
- during application dry film thickness is 40-50 mkm and at the same time physical-mechanical characteristics correspond to exploitation demands
- increased resistance to temperature differentials
- increased elasticity under low temperatures
- high resistance to different climate conditions. Resistance to ultraviolet rays
- high resistance to abrasive attrition in comparison with polyether coverings what reduces the level of defectiveness during transportation, recycling and mounting of metal with covering
- good soil-repellency properties
- surface of the covering prevent from slipping and that is undoubtedly an advantage while mounting
- service life before repair painting under usual conditions is more than 10 years
