Analysis on the Uses and Problems of Water-borne Multicolor Coatings

Liu Donghua (Fusite Paints Manufacture (Beijing) Co., Ltd. Beijing 100078)

Abstract: This paper analyzes the compositions and technical characteristics of water-borne multicolor coatings, the superiority to stone paints and natural granite, use fields and application technologies. It also analyzes the problems and gives thoughts about the solution to them, and at last puts forward the future research emphasis and trend.

0 Foreword The
colorful pattern finish paint (hereinafter referred to as multicolor coating) refers to the paint that can obtain the colorful pattern in one coat. According to its composition principle, multicolor coatings are mainly divided into 4 types: O / W (oil-in-water type), W / O (water-in-oil type), O / O (oil-in-oil type), W / W (water-in-water type) type).

At the end of the 1980s, the oil-in-water colorful interior wall coating technology (the most commonly used technology at that time) was introduced into China by Japan. After that, related domestic technologies have also been successfully developed. Its emergence was once a revolution in the field of architectural coatings. Sexual breakthrough. Multi-color paint can be sprayed at one time to display multiple color patterns at the same time. Many color particles are interlaced with each other. It is known as “seamless wallpaper”. It was widely used in the field of interior wall decoration, especially in high-end interior wall decoration. Applicability and vitality have seen “colorful phenomena” throughout the country. However, with the improvement of people’s living standards, the requirements and concerns for the environment and their own health have been increasing. In addition, the state has promoted environmentally-friendly, low-pollution and sustainable development industrial policies, especially in the 2001 “Interior Decoration Materials The introduction of the compulsory standard for the limit of harmful substances in wall coatings GB 18582-2001 made the use of multicolor coatings for interior walls restricted by the industrial policy of not conforming to national green products, and was later listed as a type of interior decoration materials to be eliminated by the Ministry of Construction.

In recent years, with the continuous development of coating technology and the continuous expansion of the emerging building energy-saving market, the application of architectural coatings has become increasingly popular and popularized, among which water-based environmental protection coatings have absolute advantages. However, most of these coatings are ordinary latex paints, elastic latex paints, and texture paints, which can only be a single color coating at one time. For public buildings and high-end residential buildings, where the facade requires stone effects, ordinary paints are difficult to achieve. . The real stone paint is sprayed multiple times to achieve the granite effect. The more the color and hue, the more difficult the construction technology is, and the more difficult it is to control the construction quality. Therefore, the water-based colorful coating technology (W / W water-in-water type) that can form multiple interlaced colors in a single spray has attracted the attention of the industry and has become a hot spot in the architectural coatings industry in recent years. Based on Fusi Special Paint (Beijing) Co., Ltd.’s many years of R & D and application experience in water-based colorful coatings, the following is an analysis of the technical characteristics, product advantages, application areas, construction processes and existing problems of water-based colorful coatings.

1 Composition and technical characteristics of water-based colorful coatings
Colorful coatings are different from traditional architectural coatings, such as acrylic coatings, styrene-acrylic coatings, etc. These coatings are single-phase, single-color uniform coating products. According to the Japanese Industrial Standard JISK5667, the multicolor coating is defined as “a paint that can obtain a color pattern with a single coating”, that is, it is composed of two phases that are immiscible with each other. One phase is a dispersed phase; the other phase is a continuous phase (dispersion medium). The dispersed phase contains two or more colored particles of different sizes, which are uniformly suspended in a dispersion medium containing a stabilizer and are in a stable state. During the construction, a special spray gun can be used to spray the particles of each color to form a variety of color effects that are intertwined but maintain their independent colors, similar to natural granite. Unlike oil-in-water (O / W) multicolor coatings, the composition of the water-based multicolor coatings contains both a dispersed phase and a dispersion medium, which are both water-based systems, which have a small impact on the environment and are more environmentally friendly. The dispersed phase mainly includes film-forming substances, film-forming aids, pigments and fillers, antifungal agents, thickeners, water-soluble colloids, etc .; the continuous phase contains various additives such as acrylic emulsions, thickeners, and preservatives. Varnish. As the hydrophilic colloid in the dispersed phase, polyvinyl alcohol, bentonite, cellulose derivatives, natural resin gums, and synthetic high molecular polymers can be used. The gelling agents are mostly inorganic salts, borate and the like.
The successful development of water-based colorful coatings is a major breakthrough in the field of traditional architectural coatings. 

The uniqueness of its technology lies in:

(1) Water-in-water technology is adopted to control the degree of reaction gel of different components to achieve a relatively balanced system. The formula design is different from the general theory of architectural coatings. 

(2) There is both a homogeneous emulsion dispersed phase and gelled particles of different colors in the product. The gelled particles of multiple colors in the product are sprayed by a special spraying tool at one time, which can form differences similar to natural granite. The effect of staggered color particles.

 (3) In the production process, the basic process different from the traditional water-based architectural coating dispersion, grinding, and paint adjustment is adopted. During production, colloids, colloidal tinting and granulation, and emulsion phase mixing and dispersion are required to prepare the product.

 (4) The product is fully water-based, and has better environmental protection and pollution-free properties than traditional oil-in-water or water-in-oil colorful coating technology.

Product advantages of water-based colorful coatings
2.1 Advantages compared to traditional real stone paint (rock chip real stone paint).

The amount of water-based multicolor coating per unit construction area is small. The construction of real stone paint is generally 4-6 kg / m2, while water-based multicolor coating only requires 0.3 to 0.5 kg / m2, which saves material. It meets the national requirements of “four sections” of energy saving, water saving, land saving and material saving. Color stability is better than real stone paint. A variety of water-based colorful colors can be achieved by color slurry prepared by industrially produced pigments, and the color of real stone paint completely depends on the color of natural colored sand. There are differences in the color of natural colored sand in different regions, and even colored sand with different depths of the same ore source. For larger projects, when the real stone paint demand is large, the color difference between different batches of colored sand is often caused by the continuation of time, which brings a certain passive situation to the production and operation of the enterprise.
Water-based multicolor coatings are easier to apply than real stone paints. According to the different natural granite imitated, water-colored colorful generally includes 5 to 10 kinds of monochromatic particles, which are formed at one time during spraying construction. Multiple colors are interlaced to give a realistic granite effect. The method of real stone paint imitation granite generally exceeds 3 It is difficult to spray the single color multiple times, and it is difficult to achieve the final effect.

2.2 Advantages compared to natural granite
2.2.1 Light weight and safer
Water-based colorful coating unit weight per square meter does not exceed 1 kg, while natural granite generally has tens of kilograms or even hundreds of kilograms. Therefore, the use of water-based multicolor coating imitation granite decoration can greatly reduce the load bearing pressure on the main body of the building. Especially with the continuous development of building energy conservation in China, the external walls of residential buildings and public buildings must be externally insulated to reduce building energy consumption. It is more difficult to carry out stone decoration construction on the external wall of the building with external insulation, and the external wall decoration using water-colored multicolor coating to imitate granite effect can be free of the limitation of the external insulation method, the construction is simple and feasible, and it is widely applicable to a variety of external walls External thermal insulation wall.

2.2.2 More environmentally friendly and energy-saving
natural stone The mining, processing, transportation, and installation process will consume a lot of natural resources, human resources, and cause damage to the environment. Water-based multicolor coating is a new type of functional architectural paint, which is environmentally friendly, non-toxic and easy to apply. It can fully realize the natural granite decoration effect, and is more energy-saving and environmentally friendly.

2.2.3 Strong creativity and adaptability
There are no restrictions on design and construction, and the shape of granite can be changed according to the designer’s intention. According to the design of the building itself, the lines and layers of the building can be reflected spiritually. It can adapt to any irregular building wall surface, and can decorate any curved, thin edges and other parts, and it is easy to realize architectural modeling design.

2.2.4 It is easy to control the batch color difference, which is convenient for later renovation and repair. It can be applied on a large area. It is easier to control the color difference between batches than natural granite, and it is convenient for later renovation and repair.

2.2.5 Lower
comprehensive cost The comprehensive cost is less than 1/3 of the natural granite comprehensive cost, which is more conducive to promotion and use.

2.2.6 Short
construction period The construction period is short. It requires the use of a professional spray gun and one-shot molding, which can greatly save construction time and shorten the construction period.

3 Decorative effect and application field ofwater-based multicolor coating

3.1 Comparison of decorative effect of water-based multicolor coating (granite paint) and stone (see Figure 1)


3.2 The main application areas of water-based colorful coatings
Natural stone has a long history of application in the field of architectural decoration. With its noble, natural, simple, and luxurious style, it has won the favor of architects and users. It is also one of the important signs of the external image of high-end buildings. . However, as China ’s protection of natural resources and the country ’s environmental protection and energy saving policies and related regulations become more stringent, the cost of mining, processing, and transportation of natural stone has continued to rise, which has affected the application of natural stone in the field of building decoration to a certain extent . In addition, the continuous promotion of building energy conservation has also made the application of exterior wall thermal insulation technology on building exterior walls popular. However, the stone decoration process on the thermal insulation base is relatively complicated, and many new thermal insulation forms cannot be adopted. Water-based colorful coatings are rich in colors and easy to construct. They can get a strong three-dimensional decorative effect after one spray, and are economically and reasonably priced. They are easily renovated and updated later. They are used by more and more construction units in architectural decoration projects. . The current application areas are mainly government and corporate office building, large office buildings, logistics centers, shopping malls, schools, hospitals, stations, stadiums and other building exterior decoration, mainly used in high-end residential building exterior walls.

4 Basic construction technology
4.1 Process flow
Wall base treatment → Scrap (wipe) smear anti-cracking mortar 1 time while compounding alkali-resistant glass fiber mesh cloth → Scrap (wipe) smear flexible water-resistant putty 2 ~ 3 times → Brush seal primer 1 time → Liquid granite intermediate paint 1 or 2 times → elastic line, division, tape application → spray liquid granite → spray varnish.

4.2 Treatment of the base surface
Before the treatment of the base layer, the wall needs a certain period of maintenance. Before construction, the loose, peeling, hollow, powdered base layer should be completely removed, and then the pollutants such as dust and oil stains should be removed.

4.3 After scraping the anti-crack mortar and alkali-resistant glass fiber mesh cloth to clean the base layer, configure the anti-crack mortar 2 to 3 mm according to the requirements of use. At the same time, spread the mesh on the anti-crack mortar and press it into the anti-crack mortar. The total thickness of the mortar is controlled between 2.5 and 3 mm to ensure that the final vertical and flatness is less than 2 mm (2 m foot rule).

4.4 Squeegeeing Flexible Water-Resistant Putty
The thickness of one coat shall not exceed 0.5 mm, and it shall be applied in two or more passes; the interval between each pass shall not be less than 5 h. After each putty is scraped, it should be polished and trimmed in time (usually 4-6 hours).

4.5 Applying the closed primer. After
the putty meets the requirements, the base layer should be polished and smoothed to remove floating dust. The fur rollers should be kept clean. Apply the water-based closed primer once, evenly, and there must be no leakage.

4.6 Applying the granite intermediate paint
After the primer is dry, apply the liquid granite intermediate paint 1 or 2 times to cover the base color.

4.7 Spraying Granite Coating
Before spraying granite coating, the intermediate paint of granite coating should be fully dried and the construction temperature must be above 5 ℃. When spraying granite coating, spraying is usually divided into 2 times. The amount of coating varies depending on the coating effect, weather, base condition, and construction method.

4.8 Spraying liquid granite varnish varnish The
varnish spray should be uniform and comprehensive, and there should be no leakage.

5 Progress of water-based colorful coatings
(1) After years of research and development, water-based colorful coating formulations and production and application technologies have basically matured. Water-based colorful coatings were first researched by Americans as their patented products. In the early 1990s, the European Patent Office disclosed water-based colorful coating components prepared based on the U.S. patent; around the mid-1990s, based on European and American studies, Taiwan turned it into a building that can now be applied to buildings. In the past few years, the coating products have gradually become recognized by the Chinese people. So far, more than a dozen coating companies in China have successively launched water-based colorful coating products. Each enterprise has different practical results according to the different technical routes and systems of research and development. Decorative effect of imitation granite stone. The technology of water-based colorful coatings is relatively mature. As a high-end product of architectural coatings, the application market of water-based colorful coatings in the field of building exterior walls is in a period of rapid growth.

(2) The decorative effect of water-based multicolor coating imitation granite has been widely used and recognized by most construction units. Fusi Special Paint (Beijing) Co., Ltd., through the joint efforts of several R & D personnel, has continued R & D for more than 3 years, and finally successfully launched a water-based multicolor coating series in 2008 (the company’s trade name is liquid granite). Up to now, more than 100 actual construction projects have achieved good results. In the communication with customers, I found that when I first saw the model or actual project of imitation granite effect of water-based multicolor coating, few people thought that it was made by paint, and the customer all simulated the natural granite of water-based multicolor coating. The effect was surprised. This shows that water-based multicolor coatings have fundamental conditions as a substitute for natural granite for building exterior wall decoration. Its stone-like decorative effect will lay the foundation for the application of water-based colorful coatings in the construction field.

(3) Water-based colorful coatings have become one of the representatives of high-end architectural coatings. The research and application of water-based colorful coatings has become a hot spot in the architectural coatings industry and an important manifestation of the R & D strength of architectural coatings companies. In recent years, there has been no major breakthrough technology in architectural coatings, mainly because the research and development of architectural coatings technology relies heavily on the development of upstream raw materials, especially emulsion synthesis and additives. Under the premise that there is no major breakthrough in the upstream products of architectural coatings, as a traditional architectural coating products mainly based on compounding and physical mixing, there is not much breakthrough in technology. The water-based multicolor coating has a high technical content, especially the key to solving the stability of the final product (storage stability and mechanical stability). There are many technical routes for paint company R & D personnel to explore. In addition, the water-based multicolor coating formulation technology involves certain chemical reaction characteristics. Different enterprises can adopt different technical approaches to achieve better results. In this regard, coatings companies can choose appropriate protective colloids and corresponding gels from traditional raw materials. Through adjustment of the amount and design of the mixing process, they can finally make water-based colorful products with corporate characteristics. Coating products. For technical R & D personnel, doing water-based colorful coatings will be more challenging and fun than traditional latex paints, and of course it will also bear more risks and pressures.

6 Analysis of existing problems
6.1 Technical problems of water-based multicolor coating products
6.1.1 Water-based colorful coatings show a layer of floating water after storage. The water-based colorful coatings consist of a dispersed phase and a continuous phase. The dispersed phase consists of a variety of different colored coatings (containing anionic colloidal substances) added to the gelling agent (different metal cations). ) Formed a mixture of colored particles with a certain stability and cohesive strength; the continuous phase is a varnish containing various additives such as acrylic emulsion, thickener, preservative and so on. Due to the relative insolubility between the two phases, a water-based multicolor coating product is formed. However, due to the difference in the specific gravity of the two or the improper control of the viscosity of the system, the phenomenon of the dispersed phase sinking and the continuous phase rising sometimes occurs during long-term storage. To reduce or solve the above problems, the specific gravity of the dispersed phase and the continuous phase aqueous solution (dispersion medium) should be fully considered in the formulation design of the water-based multicolor coating. The difference should not be too large, and at the same time, the viscosity of the system should be increased while satisfying the workability. .

6.1.2 Water-colored multi-color paints appear cross-colored or miscible
in color particles after storage . The main problem is stability. Water-based multicolor coating is not a homogeneous system like latex paint, but a metastable system composed of dispersed phase and continuous phase. The dispersed phase is a relatively stable aqueous gel formed by a certain gel reaction. After long-term storage, bleeding may sometimes occur to the continuous phase. After spraying, the colored particles are no longer a clear interface, and the continuous phase also appears. Cloudiness. The main reason for this phenomenon is that the degree of reaction between the colloidal substance and the gelling agent in the colored particles is insufficient, the particles are soft overall, and the low cohesive strength causes the pigments, fillers, additives, etc. in the colored particles to continue through the fragile protective film. Permeate everywhere, so that the continuous phase gradually brings the color of colored particles, so that the phenomenon of turbidity appears. The solution to this problem is generally to adjust the concentration or addition amount of the gelling agent. The lower the concentration of metal cations (Al3 +, Ca2 +, Mg2 +, Fe3 +, etc.) in the gelling agent, the smaller the color particles are, and the coating film formed by the gel is. It is soft and soft, and it is easy to cause the color particles to bleed into the continuous phase and the turbidity of the continuous phase; at the same time, the concentration or addition amount of the gelling agent should not be too high, otherwise excessive gelation occurs, the particles are too hard, and monochromatic particles are sprayed Poor fusion between them, the surface has a similar phenomenon of small crusts, the appearance does not look like natural granite.

6.2 Application problems of water-based colorful coatings
6.2.1 Diversity of names
In 1993, the Ministry of Construction issued the industry standard “Colorful Interior Wall Coatings” JG / T3003-93, which stipulated the water-in-oil colorful coatings. However, different companies based on water-based colorful coatings on the market have adopted various names according to their own needs, most of which are related to the decorative effect of colorful coatings, i.e. granite-like coatings, such as granite-like coatings, granite coatings, liquid granite, etc. Wait. There are not many directly named multicolor coatings on the market, indicating that the company’s market awareness is stronger and the product’s sales goals are clearer.

6.2.2 Strengthen process design and systematically guarantee the engineering quality of water-based colorful coatings. The stone-like effect of water-based colorful coatings. Although the main coating, namely colorful coatings, plays a key role in decorative effects, as a high-end product for architectural coatings, only reasonable processes can be performed. The design and combination of other excellent supporting materials can ensure the quality of the entire coating system, allowing customers to choose with confidence. For many years, there has been a tradition in the field of coatings that emphasizes formula research and despise process research. Many excellent products have not been recognized and promoted in the market because the process design is not systematically solved. Water-based colorful coatings are not materials that can achieve decorative effects alone. Reasonable process design includes the use of screeds with excellent crack resistance, alkali-resistant reinforcing materials, elastic putty, alkali-resistant primer, weather-resistant intermediate paint, and stain resistance. Reasonable selection of overprint varnish with excellent stain resistance and durability. The compatibility and compatibility between these materials and with water-based colorful coatings cannot be ignored. For a simple example, the crack resistance of the base layer is not handled well. Although the cracking phenomenon after construction is the problem of the base layer, if there is no suitable supporting solution, the construction


unit will be hesitant to choose. Figure 2 shows the cracking phenomenon in the second year after construction, mainly due to the cracking of the granite coating caused by the cracking of the thermal insulation plaster of the base layer. Therefore, water-based colorful coatings not only have to do their own formulation and technical problems, but also have a complete set of solutions in process design and product matching to help systematically guarantee the coating quality and make the promotion of this high-end product long-term. To enhance market confidence.

6.2.3 Enterprises need to strengthen special construction training to allow more construction personnel to be trained to ensure construction quality
Water-based colorful coatings have complex formulas and high technical difficulties. Construction personnel need to systematically train the nature of the materials and construction skills, tool use, air pressure control, and stubble treatment. Otherwise, even if the same batch of products or even the same barrel of products are operated by different gunners, different effects will occur, which is a major obstacle to the large-scale promotion and application of the product. Therefore, no matter the enterprise or the industry develops this product, the construction personnel must be systematically trained.

6.3 Market maintenance problems of
water-based colorful coatings The development cycle of water-based colorful coatings is relatively long and technically difficult. In addition, the production of a granite effect is equivalent to the production of 5 to 10 batches of conventional latex paint coatings, which results in the production of water-based colorful coatings. Long cycle, high risk of production process, products with quality problems can hardly be digested and processed again. Therefore, companies in the coatings industry should adhere to the high-end positioning of water-based multicolor coating products, and jointly maintain the product profits due to high-end products in the industry, and avoid premature price wars.

7 Research and Development Directions
(1) Strengthen the research on process technology, and achieve a variety of decorative effects through different process combinations. Natural granite can show different appearance effects through many different surface treatment processes. Coating companies should use a variety of traditional paint decorative effects and water-based multicolor coating decorative effects to make appropriate process combinations to achieve more creativity and maximize the advantages of water-based multicolor coating construction. Extreme, to achieve a decorative effect that is difficult to achieve with natural granite.
(2) Strengthen the research on super weather resistance, extend the application life of water-based colorful coatings, better cope with the challenges brought by the high life of natural stone materials, extend the time for refurbishing colorful coatings, and save social resources.
(3) Strengthen the research on industrialization and finished products, develop appropriate carriers, and composite molding with multiple carriers, minimize the dependence on field construction, truly achieve the finished product coatings, industrialize the coating effect, and replace more natural stone Application areas.

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