The advantages and disadvantages of common water-based anticorrosive coatings!

Water-based paint is a paint in which water is used as a solvent or as a dispersion medium

At present, common water-based anticorrosive coatings mainly include five categories: water-based alkyd coatings, water-based inorganic zinc-rich coatings, water-based epoxy coatings, water-based acrylic coatings and water-based polyurethane coatings

Water-based alkyd paint

It is made of water-based alkyd resin, pigments and fillers, various additives, and deionized water.

The characteristics are: low volatile organic content; high thickness and high hardness of one-time dip coating; excellent adhesion, corrosion resistance and outdoor durability; low odor, which is beneficial to improve the construction environment and personal health; has excellent Good flexibility and impact resistance

Disadvantages: The ester bond in the main chain of the water-based alkyd resin is prone to hydrolyze with water in water and break the chain.

Water-based alkyd paint is a new type of environmentally friendly paint with a very wide range of applications.

Water-based inorganic zinc-rich coating

Generally divided into two types: self-curing inorganic zinc-rich and post-curing inorganic zinc-rich

The characteristics are: fast drying speed; the coating has good static conductivity and excellent welding performance; excellent long-term corrosion resistance, long-term resistance to chemical corrosion within the range of pH 5.

Disadvantages: The dry film contains a large amount of zinc powder, which causes the porosity of the coating; the processing requirements for the substrate are relatively high and the paint film is relatively brittle; the construction and curing are greatly affected by the environmental temperature and humidity
.

Water-based inorganic zinc-rich coatings are widely used for long-term corrosion protection of steel structures in various environments such as ocean atmosphere and high temperature, such as offshore platforms, ships, containers, large steel components, oil pipelines, and various chemical tank linings
.

Waterborne epoxy coating

It is composed of two components: hydrophobic epoxy resin and hydrophilic curing agent
.
The waterborne epoxy coating itself contains moisture, which can become a component of the waterborne epoxy coating together with the moisture on the surface of the wet substrate
.

The characteristics are: excellent adhesion on the surface of steel, concrete, aluminum and other substrates; the coating film has the characteristics of high hardness, good wear resistance, corrosion resistance and excellent chemical resistance; low volatile organic compound content , Will not cause air pollution; odorless, non-flammable, greatly improved safety during storage, transportation and use; quick-drying, under 20 ℃ and 75% relative humidity, generally 2h can reach finger dry, the lowest curing temperature is 15°C
.

Disadvantages: The chemical resistance is still slightly worse than that of solution-based epoxy coatings, and the service life is shorter than that of general solvent-based epoxy coatings
.

The currently commercialized waterborne epoxy anticorrosive coatings mainly include: waterborne epoxy iron red primer, waterborne epoxy zinc phosphate primer, waterborne epoxy zinc-rich primer and waterborne epoxy mica intermediate paint
.

Waterborne acrylic paint

Refers to a water-based acrylic paint is mainly acrylic acid copolymer as the base material, water as a dispersant, together with fillers and additives formulated
.
Acrylic copolymer is synthesized from methyl methacrylate, butyl acrylate and acrylic acid.
According to the state of the resin in water, it is divided into water emulsion, hydrosol and water-soluble acrylic paint
.

Features: as a top coat, it has good weather resistance, UV resistance, water resistance, and non-yellowing; it can be hard-dried after 45 minutes, and can be recoated after 2 hours.
It can be used at as low as 5°C; it can be mixed with water-based It is matched with oxygen or acrylic primer and intermediate paint, and can also be used on solvent-based coatings to form a composite coating system; it has excellent corrosion resistance, excellent gloss and color retention, non-combustible and safe
.

Disadvantages: Waterborne acrylic resin coatings have problems such as high hardness and poor solvent resistance
.

Waterborne acrylic resin coatings have a wide range of uses, and can be used in various fields such as construction and automobiles, and have become a major system in anti-corrosion coatings
.

Waterborne polyurethane coating

Waterborne polyurethane coating is an aqueous polyurethane resin as binder, water, pigment, and other additives formulated
.
According to different synthetic monomers, waterborne polyurethane can be divided into polyether type, polyester type and polyether and polyester hybrid type
.

Features are: good dispersion stability; low production cost, safe and non-burning, no pollution to the environment, not easy to damage the painted surface, easy to operate; good for wood, fiberboard, plastic film, metal, glass, leather, etc.
Adhesion
.

Disadvantages: Waterborne polyurethane coatings also have long film-forming time, the presence of hydrophilic groups in the coating causes poor water resistance of the paint film, the paint film is prone to bubbles, and the cost of raw materials is high
.

Application of waterborne polyurethane anti-corrosion coatings is mainly used as anti-corrosion paint, widely used in painting railway locomotives, bridges, cars, wood furniture, architectural decoration and other
.

When water-based paint is used for heavy-duty anticorrosion protection, pure water-based paint system can be used, or a mixed system of water-based paint and solvent-based paint can be used
.
The mixed system usually uses solvent-based paint as primer, intermediate paint and topcoat are water-based paints, but it is also possible to use water-based paint as primer and solvent-based paint as topcoat for matching
.
The development of water-based coatings can not only greatly alleviate the consumption of petroleum resources, but also greatly reduce VOC emissions, which has very important economic and social significance in today's increasingly deteriorating environment and increasingly tight petroleum resources
.