Innovative architectural coating solutions

Based on the development trend of the construction industry, floor paint and wall paint put forward higher requirements for paint film performance, construction efficiency and environmental protection. Innovative two-part water-based polyurethane and poly-Tianmen dongpropy technology is fully in line with market development needs. This article describes the fundamentals of these two technologies and their application in the fields and walls. Easy-to-clean coatings based on these technologies can be used in the interior walls of buildings such as hospitals, schools, kindergartens, electronics plants, food processing plants, restaurants and stations, as well as in external walls with high durability requirements. Based on these technologies, floor paint is widely used in commercial and industrial flooring, with excellent wear resistance, scratch resistance and chemical resistance. This paper also analyzes some cases to illustrate the performance of coatings in practical applications.
Overview
latex and epoxy paint are the mainstream technologies in wall and floor paint. With the improvement of the performance requirements of architectural coatings in the market, polyurethane coatings are also used in the field of high-performance architectural paint, two-component fatty polyurethane coatings with its excellent weather resistance, chemical resistance, just softness, wear resistance and scratch resistance to become a benchmark technology for high-performance wall and floor paint. However, although the performance of traditional solvent-based polyurethane coatings is excellent, its large odor, high volatile organic compound content, and flammable and explosive properties limit the use of this technology, especially in indoor applications. Innovative two-component water-based polyurethane technology and poly-tianmen dongeethane technology are in line with market trends: high performance, environmental protection and high efficiency.
water-based polyurethane technology can be applied to floor paint and wall paint. For floor paint, the two-part water-based polyurethane is mainly used as a paint, used to protect such as solvent-free epoxy and polyurethane coating, to provide better wear resistance, chemical resistance and weather resistance, the most suitable applications include: offices, lobby, showroom, warehouse, supermarket, school, stadium and workshop. For wall paint, two-component water-based polyurethane can be described as a functional high-performance paint, can achieve easy cleaning, anti-fouling, acid rain and anti-graffiti and other properties, both internal and external walls are suitable for use, but also as texture paint and plain concrete mask varnish.
poly-Tianmen dong-ester coating can be used mainly for solvent-free floor paint, especially suitable for places with fast-moving needs. The coating package can include primers and can be applied directly to concrete surfaces treated at the base, with recommended places to use: parking lots, playgrounds and steel corrosion protection.
Basic principle of two-component water-based polyurethanes
The reaction of two-component water-based polyurethanes
the main reaction to the generation of polyurethanes is the reaction between isocyanate groups and hydroxyl polyols, as shown in Figure 1.
isocyanate also reacts with water, first producing amines and releasing carbon dioxide gases, and then amines reacting quickly with another isocyanate group to produce arbonds. Figure 2 shows the reaction of isocyanate to water.
in a two-part polyurethane system, how can we achieve water-basedity when isocyanate groups react with water? The research shows that the conventional fatty polycyanate is hydrophobic and reacts very slowly with water. When it is mixed with water, it is layered with water, and the interface in contact with water produces a polythione film that further isolates polysephate from water, creating conditions for the hydration of two-component polyurethanes for several hours of stability in water. Figure 3 shows the status of polycyanate in water.
Two-component water-based polyurethane mixing and film formation
unlike the solvent-based polyurethane coating ion phase system, the two-component water-based polyurethane components and polyol components will form a three-phase system, i.e. water (continuous phase), hydroxyl resin dispersion phase (including some polysyl cyanide in the shear force has entered the hydroxyrestrite dispersion phase) and polysyl cyanide dispersion phase. As mentioned earlier, polychloricate dispersion phase small droplet surface will have a very small part of the NCO and water reaction, the formation of polycarbone membrane, this layer of polycyclic membrane plays a protective role, so that the NCO inside the droplet will not react with water at this stage, thus ensuring that the coating has sufficient operanability time.
, however, the application period for the mixing of two-part water-based polyurethanes cannot be judged by the increase in viscosity, which is different from traditional solvent-based polyurethanes. The viscosity of the two-component water-based polyurethanes after mixing is usually stable, and sometimes there is no significant change in viscosity even after the mixing period, mainly because some of the chemical reactions that occur in the dispersed phase are not sufficient to affect the flow of the continuous phase. Therefore, we can not use viscosity changes to determine the two-group water-based polyurethane mixing application period, but also by measuring some properties to determine, such as gloss value, fog shadow value and solvent resistance and so on. Figure 4 shows the mixing process of two-part water-based polyurethanes.
the coating is applied by different methods, such as spraying and rolling coating, the film-forming process begins. The first step is physical drying, mainly the volatile and dispersed phase gel of water (Figure 5, Figure 6).
At this time, with the evaporation of water, the distance between the small droplets of polyol dispersion and the small droplets of polyheterate is getting closer and closer, when the distance between them is close to a certain extent, under the force of capillary force to break the wall and fuse with each other, at this time the second step of the chemical drying process began (Figure 7).
The paint film formed by chemical cross-linking has properties comparable to traditional solvent-based polyurethane coatings: excellent chemical resistance, scratch resistance, wear resistance and weather resistance, for example, and a significant reduction in volatile organic compound content.
hydrohydrate curing agent
for two-group water-based polyurethane
for excellent appearance and performance, polyheterate curing agents need to be fully dispersed in a multiphase system. Traditional hydrophobic polychyanate requires high shear dispersion using specific equipment and is not suitable for construction site construction requirements of architectural coatings, while hydrophobic polychyanate makes manual mixing possible. Figure 8 shows the dispersion of hydrophobic and hydrophobic polycyanic acid in the water when it is hand-mixed, and the performance of the paint film will be significantly affected if the mixing is inadequate.
In order to achieve the hydrophobicity of curing agents, Coxtron did not use the method of external addition emulsifying agents to prepare hydromassive polyocyanate, but the use of internal emulsification method, that is, hydromassive groups directly and polyheterate chemical binding, thus forming an emulsifying agent structure of the entire molecule, this method avoids the free external added emulsification agent may bring about a decline in water resistance and other issues. Figure 9 compares the hydrophotic changes of two types of polyseocyanate.
the hydrochemical modifier of the simplest curing agent can be achieved by isocyanate and hydroxyl polyether chemical interlinking, by the ether chain to play non-ion hydrophobic modified, but this change usually reduces the function of polyheanate. Figure 10 is a typical polyether-modified hydrophobic polychloride.
Because the decrease in function usually results in a decrease in the performance of the paint film, in order to improve the performance of the body, the NH on the urethane key can be further dextaminated, a new HDI trimer on the branch, so that the modified hydrophobic polychloride's official function is improved. Figure 11 shows.
the latest research is the hydrophosphatate-modified use of amino sulfonates (Figure 12), which helps to further improve the drying speed, hardness and chemical resistance of the paint film. In addition, this curing agent has better anti-graffiti and cleaner resistance than polyether-modified curing agents, making it more suitable for use in high-performance coatings with easy cleaning requirements.
is also one of the factors affecting dispersion, and low-viscosity polysylyanate is more easily dispersed evenly by hand. Table 1 lists the common hydro-hydrophosphate, of which AS3 is the preferred solution for architectural paint, which can be stirred by hand without solvent dilution to achieve a good mixing effect.
multi-alcohol dispersant selection
Hydroxypropyl acrylic dispersion is a two-group water-based polyurethane system commonly used resins, usually primary dispersion (emulsion-type polymer) and secondary dispersion two categories. Primary dispersants are prepared by emulsion polymerization, usually using exonerators to stabilize emulsion particles, secondary dispersions are in solvent ionization and emulsification dispersion, polymer molecular chain of the acid group plays the role of internal emulsion agent.
primary dispersions tend to have a high molecular weight and are free of organic solvents, they are ideal for fast-drying coatings but not for high-gloss systems. Secondary dispersions often contain 1-8% solvents due to the production process, making them suitable for use in high-gloss systems, but the drying speed is relatively slow.
different appearances and properties can be achieved by using a single or combined use of different types of hydroxypropyl acrylic dispersions. A typical matte system is based on the A57 or A46, and when the B46 or B95 is mixed, its comprehensive performance can be further improved and different performance can be obtained by different mixing ratios. B46 or B95 is commonly used in high-gloss systems. Sometimes we also need highly flexible coating solutions, such as those for sports pitches, which can be achieved by mixing hydroxy polyurethane dispersions.
NCO / OH equivalent ratio
Due to the side reaction between NCO and water and other active groups, the equivalent of NCO/OH in two-group water-based polyurethanes does not choose 1:1, but will choose NCO excessive, which is significantly different from the traditional solvent-based two-part polyurethane, usually to ensure that all hydroxy reactions are complete, NCO/OH equivalent ratio is selected between 1.5 and 3.0. Higher NCO/OH equivalent ratio will get better final performance of the paint film, but because the non-timely reaction of polycycyanate in the paint film plays the role of plasticizer, coating drying speed and early hardness establishment will be slower, more polychyanate curing agent dosage also means higher costs. After taking into account the cost-effective factors, the NCO/OH equivalent ratio selection between 1.5 and 2.0 is more appropriate.
the performance of the two-part water-based polyurethane coating
gangally soft
cured polyurethane paint film contains a large number of urethane bonds and arginoid bonds, which form hydrogen bonds between the polymer chain segments. Under the external force, the hydrogen bond will be disconnected and re-bonded with other bonding groups, which is the reason why the polyurethane paint film is just soft, which is also the two-group water-based polyurethane paint film has excellent wear resistance and anti-scratching important reasons. Especially for applications such as floor paint, scratch resistance is an important index to measure the quality of paint. For a long time, however, scratch-resistant testing methods and standards have not been recognized in the flooring industry, and many times they are perceived only by nail carving, which is clearly not reproducible and standard. A feasible method refers to GB/T 9279/ISO 1518 for testing (Method 1), that is, with the specified test probe at a speed of 30-40mm/s, in different loading over the model (running distance 65mm), loading weight is usually 100 to 2000g, by recording the loading weight of the paint film cut to judge the paint film scratch resistance. This method to paint film "scratch" to determine whether the anti-scratching is in line with the actual situation, there are still some objections in the industry. Another method to test scratch resistance (method 2) is to choose the standard 0000 flexible sandpaper, in different loads under the recidivation scratching model, currently often used 335 grams and 900g two loads, respectively, recidivation scratch 20 times and 10 times, and then by measuring the gloss changes of the paint film to determine the anti-scratching. This method is close to the actual scratch resistance requirements, but there is a need to further standardize the sandpaper, process and equipment tested. Based on the above two methods of testing, the preferred two-component water-based polyurethane has excellent scratch resistance, part of the test data as shown in Table 3.
easy to clean
floors and walls are often exposed to different contaminants, and easy and thorough cleaning of these contaminants is the desired performance of the market. The first step in assessing ease of cleanliness is to screen the source of the contamination. In the tests, we selected drinks, condiments, whiteboard pens, children's watercolor pens and crayons that we often encounter in our daily lives, and tested permanent markers under the most demanding conditions. The two-pack water-based polyurethane is excellent for easy cleaning and can be used to remove all kinds of pollutants with different cleaning methods, even if there have been days of contamination. Table 4 lists the anti-fouling test results.
Smeat resistance
the outer wall can often be found after the rain residue of black pollution marks, this is due to rain to bring pollutants to the wall, summer high temperature makes the paint film softened, the pollutants firmly grasp the surface of the paint film, not easy to be removed, thus affecting aesthetics. The two-part water-based polyurethane paint film is formed by chemical crosslinking and has a high glass transition temperature, so it does not soften at the high temperature of summer sunlight, thus avoiding the firm attachment of contaminants and paint film. And with a certain hydro-hydropitable paint film will also enable rainwater to evenly immerse the entire paint surface, and evenly wash the dust attached to its surface and other pollutants, play a role in cleaning the surface. Based on these two factors, the two-group water-based polyurethane coating has excellent soil resistance.
Mystic / algae-resistant
The anti-mold properties of coatings used in places such as bathrooms and food processing plants are often mentioned, which is enhanced by the addition of mold-resistant and algae-resistant agents to coating formulations. Table 5 shows the following experimental data: the anti-mold agent and anti-algae agent were added to a single-pack latex paint and two-part water-based polyurethane, and the residue of anti-mold and anti-algae agents in the paint film was tested for 2, 10 and 20 days, respectively.
test results show that the two-component water-based polyurethane thermo-cured paint film retains more mold-resistant and algae-resistant agents after water showering, which means that the paint film is more durable.
heat-resistant tire marks
for the parking lot floor paint, very concerned about the performance of heat-resistant tire marks. When the vehicle is driving for a long time, usually the tire will heat up, the plasticizer in the tire easily migrates to the rubber surface, in the case of pressure, the black tire marks can easily remain on the floor paint. To simulate this situation, we used the following test method: apply 60kg pressure on the tire test piece of 4 x 4cm2, place it at room temperature for one day, then place it at 50oC for 3 days, and then check the tire imprinting on the surface of the paint film, if there are tire marks, continue to wipe with alcohol, check the removal. Figure 14 shows the test results of two-part water-based polyurethane coatings with different crosslinking densities. Scenario 2 is based on the B95 and AS1 coating formulations, which are a high crosslink density scheme that shows the best performance against heat tire marks. The different polyurethane coatings used in the tests were able to remove any remaining tire marks from them with alcohol, which is consistent with our basic inference that they are high