What are the technical problems in the development of imitation coatings?

Lead

As a kind of high-performance coating, stone imitation coating can play a good role in imitating granite decorative effect on the exterior wall of the building, and the construction is simple, with high stain resistance and high weather resistance, but the price is only 1/2 of natural stone, and the weight is only 1/4 to 1/3
of real stone paint.

Stone imitation coating, also known as liquid stone, stone imitation paint, is suspended by two or more water-based color particles in the aqueous medium layer, with acrylic resin emulsion and elastic resin solution as the base, through the reasonable ratio and color matching of white quartz sand and artificial calcined colored sand, sprayed by high-pressure spray gun, showing a rich imitation stone coating
.
Common stone imitation coatings include synthetic resin emulsion sand wall coatings, "water-in-water" and "sand-in-water", and the recent popular "sand-in-sand" coating online coatingol.
com
.
Imitation stone paint includes real stone paint, imitation sandstone paint, imitation marble paint, imitation weathered fossil paint, imitation French wood grain stone, imitation agate stone, imitation jade, imitation granite paint, imitation travertine paint, etc
.
Imitation stone paint has a natural and real natural color, giving people an elegant, harmonious and solemn sense of beauty, suitable for indoor and outdoor decoration of all kinds of buildings, especially on curved buildings, can achieve vivid and realistic effect
.
The upstream of the stone imitation coating industry is mainly the raw materials required for manufacturing, including quartz sand, acrylate emulsion, ethylene glycol monobutyl ether, etc.
, and the downstream of the stone imitation coating industry is mainly the construction industry and the decoration industry
.
Statistics show that the market size of imitation stone coatings increases
with the continuous expansion of the demand scale of the downstream industry.
Three years ago, the market size of China's stone imitation coating industry was 5.
689 billion yuan, and two years ago, the market size of China's stone imitation coating industry was 9.
212 billion yuan
.
China's stone imitation coating industry has increasingly become the mainstay
of the entire architectural coating industry.
With the continuous improvement of stone imitation coating industry technology and the continuous growth of the consumer market, the stone imitation coating industry market shows amazing growth potential and broad market
prospects.

Characteristics and categories of imitation stone coatings

From the point of view of characteristics, stone imitation paint is a very difficult type of paint
in art paint.
The use of paint imitation stone, its effect image is vivid, whether it is texture or color, it is close to natural stone, but it is slightly lacking
in hardness.
In terms of surface décor, imitation stone paint has different colors, full of beauty, strong simulation, and the three-dimensional sense and multi-color decorative beauty of the finished surface are irreplaceable by any coating
.

In terms of solid materials, stone imitation coatings have more waterproof and crack resistance, water and alkali resistance, weather resistance, washing resistance, stain resistance, algae imitation and chemical resistance than general high-grade exterior wall
coatings.

Stone imitation coatings can be combined
well with various other coatings.
Combined with elastic coatings, it can improve crack resistance and stain resistance, and the appearance of the decors is more innovative; Combined with relief modeling paint, it can produce a thick texture of stone
.

There are two main types of stone imitation coatings
.
The first is granite paint (multi-color coating), which is formulated with pure acrylic resin emulsion or silicone acrylic resin emulsion and natural stone crystal particles of various colors
.
Excellent weather resistance, no fading, no cracking, can maintain a long life
.
Referring to the surface structural characteristics of various granite rocks, granite imitation stone paint has good texture, realistic color, elegant tone, and can formulate a variety of natural rock decorative effects to meet the decorative requirements
of various imitation natural stones.
The second is real stone paint, a kind of sand wall paint, direct spraying, the decorative effect has the texture and color
of natural stone.
Buildings decorated with real stone lacquer not only have the luxurious appearance and hardness of stone, but also have artistic effects
such as a strong sense of three-dimensionality.

Development and application of stone imitation coatings

Natural stone has a long history of application in the field of architectural decoration, and its noble, natural, simple and luxurious style is favored by architects and users, and it is also one of the important symbols of the external image of
high-end buildings.
However, with the protection of natural resources in China and the country's environmental protection and energy-saving policies, relevant laws and regulations are becoming more and more stringent, the mining, processing and transportation costs of natural stone continue to rise, which affects the application of
natural stone in the field of building decoration to a certain extent.

The continuous promotion and development of building energy conservation has also made the application of exterior wall insulation technology on building exterior walls popularized
.
The stone decoration process on the insulation base layer is relatively complicated, and many new insulation forms cannot be adopted
.
Liquid stone colorful coating because of its rich color, convenient construction, after a spraying can get a strong three-dimensional decorative effect, and the price is economical and reasonable, late renovation, update is convenient, in the building decoration project is more
and more used in construction.

At present, the application field and scope of stone imitation coatings are mainly based on the façade decoration of government departments and enterprise office buildings, large office buildings, logistics centers, shopping malls, schools, hospitals, stations, and stadiums, and the building facades of high-end residential areas are also gradually adopted
.
Cement walls, stainless steel, metal aluminum plates, plastics, glass, tiles, EPS boards, FRP, GRC and other materials can be used
.

In terms of construction, stone imitation coatings have corresponding requirements, and the walls that need to be constructed are suitable for concrete or cement interior and exterior walls and brick walls, as well as asbestos cement board, wood board, gypsum board, polyurethane foam board and other substrates
.
The surface base layer of the construction substrate should be flat, clean, and have good strength, the new wall should be dry for one month before construction, the old wall renovation, first to level the base layer, remove loose, peel off the surface layer and dust and oil scale and other impurities before construction
.
For substrate construction, first do a good job of flat scraping, and then make the base oil according to the demand, brush a layer of base film
.
Then design the brick size according to the requirements, and then make a brick model with a wooden frame or masking paper on the wall that has been coated with primer, spray the imitation stone paint, and remove the wooden frame or masking paper before the imitation stone paint has not yet dried
.

Technical analysis of stone imitation coating industry

The coating of the imitation stone paint is very hard after drying, and the nails cannot be picked
.
General stone imitation paint should be regarded as too soft
if it can still be picked with a fingernail after 3 days of application under good weather conditions.
The main reason is that the selected emulsion is not appropriate
.
In the preparation of multi-color stone imitation coatings, the same emulsion as the preparation of latex paints is used, which leads to a low emulsion content in the multi-color paint formulation, and the coating is not tight
enough due to the presence of a large amount of sand and gravel during film formation.
After the research of coating developers: the bonding strength of the emulsion used for the preparation of multi-color coatings should not be less than 3MPa, and the minimum film-forming temperature should not be lower than 15 degrees Celsius
.
A higher minimum film-forming temperature may cause the disadvantage that it is not easy to form a film at a low temperature, which can be solved
by adding more film-forming additives appropriately.
Film-forming additives can be completely volatilized after the coating is dried, and generally do not affect the performance of
the coating film.
The multi-color coating chooses a composite emulsion with high adhesion and a higher minimum film-forming temperature, which fundamentally solves the problem that
the coating is too soft.

Some colorful paint coatings turn white after each rain, the coating becomes loose, and after the rain stops, the coating returns to its original color
after the sun shines.
In fact, this is caused by the poor water resistance of the coating and the absorption of moisture, the formula is because the selected acrylic emulsion needs to add surfactants during synthesis, and some manufacturers use surfactants in order to increase the stability of the emulsion; Some manufacturers add substances such as carboxymethyl cellulose, hydroxyethyl cellulose as thickeners when preparing real stone paint, and sodium benzoate as a preservative
.
These substances are water-soluble or hydrophilic, and the coating is left in the coating after filming, which greatly reduces the water resistance of the coating
.
The experimental results show that the water absorption rate of the coating formed by spraying the pure propylene emulsion with quartz sand mixed with quartz sand without any additives is 0.
42%; On the basis of the above coating, 0.
4% hydroxyethylcellulose is added, and the water absorption rate rises to 4.
3%.

Since the coating of real stone paint is thick, once the moisture is absorbed, it is not easy to release it in a short time, resulting in a whitish
appearance.
If silicone modified acrylate emulsion (silicon acrylic emulsion) and suitable additives are used, the coating has good water resistance after drying, and the coating will not whiten when exposed to water after
drying.

Technical problems in the stone imitation coating industry

Color difference of imitation stone paint refers to the color of the coating sprayed during the construction process is not uniform, there are dark and light
.
There are many reasons for the color difference of imitation paint, the main reason is the construction
.
Many users buy materials by themselves and carry out their own construction, and the result is color difference
.
It is not appropriate
to conclude that there is a problem with the imitation stone coating of the production enterprise without analyzing the problem clearly.
Generally, professional stone imitation coating manufacturers will provide customers with standard construction processes
.
Construction must be carried out
in accordance with standard processes.
For example, the same wall should be done all at once; One wall should use the same batch of goods; The primer and topcoat should be matched, and the standard dosage should be strictly implemented in each process, and no corners
should be cut.

In order to reduce costs, some customers reduce the amount of alkali-resistant primer area, or add a large amount of water in the primer to increase the coating rate, which leads to a serious decline in quality, and the color difference
of the late coating is alkali flowering.

The anti-alkali sealing primer is applied unevenly, there are missed coatings, the coating absorption primer is uneven, and the part with less primer absorption will absorb the emulsion in the main coating stone imitation coating layer, which will lead to color difference
.

The product system does not match, and the supporting products
are replaced without authorization.
Some customers feel that the manufacturer's primer or topcoat is too expensive, and choose a lower price and low-quality finished product, resulting in color difference
.

One wall does not use the same batch of products, because colored sand is a natural substance, each batch of raw materials may have a slight color difference, but the same batch of stone imitation paint will not have color difference
.

One wall should be completed at the same time to avoid stubble
.
Uneven spraying, varying coating thickness, resulting in color difference
.
The stone imitation coating is properly sanded with sandpaper after the main coating is dried to avoid floating sand hanging ash
.
In order to avoid rain affecting the coating performance, emulsions with better water resistance can be used, such as pure propylene emulsion and silicon acrylic emulsion
.