The most comprehensive introduction to color-coated steel sheets（PPGI/PPGL） in history

Introduction: In this issue, we will explain color-coated panels from the aspects of substrate, topcoat, and application.

Substrate Type	Features	Application
Cold rolled steel sheet	The corrosion resistance is poor and the cost is low.	Lining parts of metal furniture, lamps, wire boxes, etc.
Hot dip galvanized steel sheet	The zinc layer of hot-dip galvanized sheet is thicker, which is suitable for preparing color-coated sheets with higher corrosion resistance and less demanding decorative properties.	External wall panels, roof panels, garage doors, etc.
Hot dip aluminum zinc steel sheet	The production process is basically the same as that of hot-dip galvanized sheet, mainly adjusting the composition of the molten bath and classifying according to the aluminum content. Due to their good corrosion resistance and processability, they have begun to replace hot-dip galvanized sheet.	Strongly corrosive outdoor environment

Paint Type

1.Alkyd resin coating Alkyd resin is made from the polycondensation of polyols, polybasic acids and fatty acid esters. Its performance is closely related to the type of modified vegetable oil and the oil content. There are many varieties of alkyd resins.

• Their characteristics are as follows:
• ①Has good flexibility, adhesion and mechanical strength.
• ②The pigment has good dispersion in this coating.
• ③The coating has good durability and good gloss retention.
• ④The paint film is plump, has good solvent resistance and heat resistance, but poor water resistance.

This coating is widely used in construction engineering doors and windows, wooden furniture, ships, bridges, mechanical and electrical products, optical instruments, various carriages, etc.

2.Acrylic resin coating Acrylic resin is polymerized from monomers such as acrylic acid or methacrylate, nitrile, and amide. Due to the different monomers used, it can be made into two major types of coatings: thermoplastic and thermosetting.

Thermoplastic coatings have good hardness, light color without yellowing, and good durability. They are mainly used for aluminum alloy surfaces that require good weather resistance and gloss retention in the aviation industry.
Thermosetting coatings have excellent physical and mechanical properties, good surface fullness, strong weather resistance, good color retention, high brightness, high hardness, certain water resistance and oil resistance, and most of them are cured by high temperature baking. They are suitable for cars, light industrial products, household appliances, etc.

3.Polyester resin coatings Polyester resins are polymerized with diols and dibasic acids as the main components. Coatings containing polyester can obtain a variety of physical properties, that is, they can have both hardness and flexibility. They also have excellent chemical and heat resistance and good formability. They are mainly used for building linings, transport vehicles, etc.

4.Silicone modified fine coatings are made of acrylic or polyester combined with silicon. They have good surface durability and non-powdering and gloss retention. Although limited in flexibility, they are suitable for general medium roll forming for construction. Typical uses are exterior occasions, especially prefabricated industrial buildings and residential side walls.

5.Phenolic resin coating is one of the most widely used types of coatings. It is divided into two types: modified phenolic resin coating (such as rosin-modified phenolic resin) and pure phenolic resin coating.

• (1) Modified phenolic resin coating, the phenolic condensation polymer made from phenol and aldehyde is then combined with the unsaturated ring of rosin acid, and finally the carboxyl group of rosin acid is esterified with glycerol to obtain the rosin modified phenolic resin. It has With good drying properties, durability and water resistance, it is widely used in furniture, doors and windows, etc.
• (2) Pure phenolic resin coating: produced by the condensation polymerization of formaldehyde and p-alkyl or p-aryl substituted phenol. It has good water resistance, chemical resistance and weather resistance, and can be used in ships, aircraft, electrical insulation, etc. The above two coatings are soluble in aliphatic hydrocarbons, aromatic hydrocarbons, turpentine and other organic solvents.

6.Epoxy resin coatings The molecular structure of epoxy resin contains epoxy groups. Commonly used epoxy resins are high molecular weight compounds formed by the polycondensation of epichlorohydrin and diphenol propane under the action of alkali, referred to as bisphenol A epoxy resin. It has a linear structure and can be cross-linked and cured into a film by adding amines, organic acids, acid anhydrides and other synthetic resins. Bisphenol A epoxy resin has polar groups such as hydroxyl groups, epoxy groups, and ether bonds in its structure, which generate attraction and form chemical bonds, so it has strong adhesion. In addition, it also has good chemical stability, alkali resistance, organic solvent resistance, high toughness and mechanical strength. Epoxy resin has high volume resistance and breakdown voltage, so it has good electrical insulation. Epoxy resin coatings are often used as primers.

7.Fluorocarbon coatings are precious coatings with an outstanding combination of properties, including formability, color retention, anti-powdering and solvent resistance. These coatings have a medium gloss and are produced in a limited range of colors. Their typical use is for building wall skins, roofs, curtain walls and housing side walls.8.

8.Fluorocarbon/acrylic/polyester hybrid coatings These coatings combine the economics of acrylic and polyester with the outstanding performance of fluorocarbon resins. They have good manufacturing characteristics and can withstand long-term exposure in moderately corrosive environments. They are commonly used on residential side walls and partitions.

9.Polyvinyl chloride plastisol is mostly used in applications that require a durable and weather-resistant surface and resistance to scratches during loading and unloading. This is a multi-purpose material, typically used for wall coverings, roofs, partitions, shelves, electrical component boxes, flat panels, car wing reflectors, etc. Films can also be laminated on the plastisol coating according to user requirements.

10.Polyvinyl chloride organosol has excellent formability and good decoration, and is also relatively wear-resistant. The thickness of the usual application is 40-60um/side, and the maximum thickness can reach 100um/side. Its typical use is for deep-drawn parts such as paraffin containers and lawn mower covers, as well as protective linings and gaskets for metal containers. It is composed of polyvinyl chloride, softener, and solvent, and can be firmly adhered using a special primer.

11.Strippable coatings. These are coatings that are applied temporarily. They are widely used to protect high gloss coated panels during manufacturing and transportation. They protect the surface from scratches and serve as positive markings during forming, assembly and decoration (this type of coating is only used on the front). They are often left on the product until it is sent to the end user to ensure a fresh appearance. Common uses are as protection for exterior building siding and sidewall panels to allow for forming and shearing at the construction site, as well as for automotive decoration, home appliances and a variety of other products.

12.Weldable zinc-rich primers. These coatings have weldable properties, especially for the welding and forming performance required by the automotive industry. The average film thickness is 15um while meeting the deformation and corrosion resistance requirements.

Topcoat types

Ordinary polyester color-coated products (PE):

• Features: The overall performance is very good, its good weather resistance and mechanical processing performance can fully meet the general requirements of building exterior use.
• Two kinds of primers are available: Epoxy primer: epoxy system primer, with excellent corrosion resistance and adhesion. PU primer: polyurethane primer, with excellent mechanical processing performance and corrosion resistance, universal primer.
• Scope of application: outdoor parts of industrial plants and commercial buildings such as roofs, exterior walls

Home appliance polyester color coating products (JJ):

Note: Except for solar water heater panels, all color-coated home appliance panels are environmentally friendly products that comply with the ROHS directive.

Classification and characteristics of color-coated products for construction

Colored stone carving and color coating products:

Suede effect color coating products:

It belongs to the ordinary polyester system, with low gloss (0-10%) surface and unique wrinkled appearance. It is used for interior door panels (decorative purposes).

Reticulated effect color coating products:

With its unique appearance and beautiful microstructure, the textured products will provide a new development growth point for the existing market, whether used as indoor decoration or outdoor use. Its film-forming mechanism: During the film-forming process of the topcoat, by controlling the furnace temperature and wind speed, the surface tension condensation effect occurs, producing a textured effect with a hand feel.

Printed color-coated products:

Printed color-coated products are one of the representatives of high-end products, and have begun to gradually replace traditional PVC films, completely solving environmental protection issues. Its products adopt a special roller coating process to produce continuous color patterns, which are widely used in the interior panels of the building decoration industry, and can be used as interior wall panels, ceilings, doors and windows, etc.