Principle and technical route of anti-graffiti coating

At present, the construction industry, including municipal engineering, has an increasing demand for anti-graffiti coatings.
For example, in order to solve the problems of messy graffiti and small advertisements, local governments have been seeking high-quality and environmentally friendly anti-graffiti and anti-stick coatings.

01.

Market scale of anti-graffiti coatings

The anti-graffiti coating market in 2018 was US$72 million and is expected to reach US$87 million by 2023, with a compound annual growth rate of 3.
8% during the forecast period.

02, the principle of anti-graffiti and anti-sticking

Anti-sticking and anti-graffiti materials can be divided into two types according to their film-forming forms: film-forming and non-film-forming com" href="">coatings online coatingol.

com .

① Film-forming materials, commonly referred to as paints, are coated on the surface of the protected substrate to form a continuous coating film.

The coating film has low surface tension and can be used for anti-sticking and anti-graffiti At the same time, it has certain anti-corrosion and anti-aging characteristics.

② Non-film-forming materials, used for porous substrates, applied to absorbent surfaces such as concrete and stone, and penetrated into the pores of the substrate.

Although they cannot form a continuous coating film, they can also change the surface energy of the material surface, which appears to be hateful.
Water and oil repellent, prevent graffiti paint from penetrating into the substrate, play an anti-graffiti effect, and also have an anti-sticking function.

03.
Technical route of anti-graffiti and anti-stick coating

According to its protective properties, anti-graffiti coatings can be divided into sacrificial anti-graffiti coatings, semi-permanent anti-graffiti coatings and permanent anti-graffiti coatings.

① The sacrificial anti-graffiti coating is usually a paraffin emulsion or a mixture emulsion of paraffin and polysiloxane.

After the surface of the material is contaminated by graffiti, the coating is removed together with the graffiti.
The characteristic of this kind of paint is that the paint needs to be applied again every time the graffiti is removed, which increases maintenance manpower and material resources.

② The semi-permanent anti-graffiti paint is acrylic resin paint or epoxy or polyester resin cross-linked paint, which can be applied multiple times.
It has a certain degree of corrosion resistance to strong chemical cleaning agents, and can resist several cleanings with chemical cleaning agents, but in the end a new coating is needed to replace it.
Since pollutants have a certain degree of adhesion to the coating and with the increase of time, the degree of adhesion and integration into the coating will become more and more strengthened, and strong chemical cleaning agents must be used for cleaning.

③ Permanent anti-graffiti coatings have a relatively long service life.

Using safe neutral cleaning agents or no cleaning agents can remove graffiti, stickers or other contaminants on the coating surface many times without losing the coating itself.

The permanent anti-graffiti and anti-stick coatings on the market are mainly divided into fluorine-modified or silicon-modified polyurethane, fluororesin coatings, elastic polysiloxane coatings and silicone resin coatings according to their chemical composition.

① Fluorine-modified or silicon-modified polyurethane coatings are usually copolymerized with fluorine monomers and acrylate monomers, or silicon monomers and acrylate monomers are copolymerized, and then crosslinked with isocyanate curing agents, usually a two-component system.

It needs to be mixed well before application.
In addition, some anti-graffiti resins or additives are added to achieve the anti-graffiti function.
After repeated cleaning, the anti-graffiti function will decrease.
Usually this kind of coatings are solvent-based products, which will use more VOC emissions during construction.

② Elastic polysiloxane coating has good anti-graffiti function and durability, but it is also a solvent-based product.
However, the paint film is soft, and the ability to resist mechanical damage is relatively poor, and it is also easy to stain dust.

③ The water-based two-component anti-graffiti coating has a lower VOC content and is more environmentally friendly.
The film-forming material is usually acrylic polyurethane modified with low surface energy materials.
Due to the use of emulsifiers in its resin synthesis, its anti-graffiti performance is weakened.
The pollution of water-based pens can be easily removed, but the pollution of oil-based pens still needs to be wiped off with alcohol.

   

④ One-component solvent-free moisture-curing silicone resin coating is a more environmentally friendly system.
It adopts the latest technology to synthesize low-viscosity silicone resin.
It can achieve lower application viscosity without adding solvents.

Its odor is lower, its VOC content is lower, and its VOC content can be less than 60 g/L.
Since its composition is 100% silicone resin, high-density methyl groups can be aligned on the surface of the coating, so it has a particularly low surface energy.
Even if the oil-based pen paints on the surface, it can be easily wiped off with a dry cotton cloth, eliminating the risk of using cleaning agents.

Graffiti is a global problem, and at the same time it brings huge challenges to the coatings industry.
Although graffiti cannot be prevented from graffiti, some fresh and ingenious methods can be used to deal with it.
Surface coatings can be used.
It not only protects the substrate, but also makes the graffiti cleaning much easier.

Although the graffiti problem is serious in some countries, it has not attracted enough attention from the coatings industry.
With the use of these coating systems, the headache of graffiti can be solved to a large extent.
A variety of new anti-graffiti multifunctional coatings have been successfully developed, which will undoubtedly play an important role in the protection of urban buildings and the maintenance of city appearance.