Preparation and Properties of One-component Acrylic Waterproof Coatings

YE Xiao-min, ZHOU Chu
(BATF Industry Co., Ltd., Foshan 528322, Guangdong, China)

Abstract: One-component acrylate waterproof coatings were prepared with the polymer acrylic emulsion as the main filmforming material and pigments, fillers and other additives through the three-roll grinding process. The effects of different pigments and fillers on their properties were studied.

0 Preface
One-component acrylate waterproof coating is a one-component water-emulsion waterproof coating made by using polymer acrylic emulsion as the main raw material and adding other additives. With the rapid development of China’s construction industry, the protective effect of waterproof coatings on waterproofing and moisture-proofing of building structures has also attracted widespread attention. One-component acrylate waterproof coating is a polymer acrylic emulsion-based waterproof coating, which has many advantages such as acid and alkali resistance, good water impermeability, good low temperature flexibility, excellent durability, no environmental pollution, and convenient construction. The waterproof coating has high elongation and excellent elasticity, and is bonded to the base layer to form a complete waterproof system that is rigid and flexible. It can adapt to certain structural deformation and achieve long-term waterproof protection. And it is corrosion-resistant, light-resistant, weather-resistant, non-toxic, odorless, and no pollution to the environment. It is a new type of environment-friendly material. In recent years, with the rapid development of the construction industry, housing construction has been a hot topic that people have been paying attention to and discussed. Occasionally, the problem of complaints from owners due to house leakage has occurred. The leakage of the house construction not only destroys the living environment, causes endless distress to people, but also shortens the service life of the building. Due to its unique performance advantages, one-component acrylate waterproof coating has been widely used in many important industrial and civil building roof waterproofing, and other non-long-term water-soaked building waterproofing projects. This article uses acrylic emulsion RS-3003 as the main base material, and chooses one or more of 325 mesh calcium, 800 mesh calcium, talc, titanium dioxide, calcined kaolin, mica powder, and other additives. Prepared. During the product preparation process, due to the high proportion of powders that need to be dispersed, the method of adding the required amount of emulsion two times in order to achieve the effect of uniform dispersion of the powder; after the dispersion is uniform, it is ground by a three-roll mill Discharging process, the prepared waterproof coating has excellent properties such as high elasticity, excellent elongation and good adhesion.

1 Experimental part
1.1 Main raw materials: styrene-acrylic emulsion RS-3003, Bardford; dispersant 5040, defoamer SN-154, defoamer NXZ, Nopco; thickener TT-935, multifunctional auxiliary AMP-95, USA Dow; preservative GT-50, Erichsem; ethylene glycol, heavy calcium CC-325, heavy calcium CC-800, talc, calcined kaolin, titanium dioxide 706, mica powder, commercially available industrial grade.
1.2 Experimental equipment (see Table 1)

Main equipment

1.3 Coating formula (see Table 2 and Table 3)

Coating formula
Powder ratio

1.4 Preparation process
1.4.1 Preparation process
Disperse the pigments and fillers in the system at high speed with a disperser using 50% of the formula emulsion and water, and then sequentially Add SN-5040, SN-154, ethylene glycol, fully infiltrate and disperse the pigment and filler, and then add the remaining 50% of the emulsion and stir well to obtain a fine slurry. Then add TT-935 to thicken the slurry. ; Add APM-95 to adjust the pH of the system, and finally add NXZ to defoam, stir and disperse evenly, and then grind and discharge through a three-roller machine, and then package.
1.4.2 Precautions
in preparation In the process of preparing coatings, because the powder density is too high, do not feed it all at once to avoid the powder from clumping without being sufficiently wetted, so that it is difficult to disperse uniformly, or the product volume is too large after the clumping occurs, making the slurry Material overflow; when grinding slurry with a three-roller, the equipment must be used in strict accordance with the three-roller operation requirements to avoid operating accidents.
1.4.3 Process flow chart (see Figure 1)

Schematic diagram of the preparation process of one-component acrylic waterproof coating

1.5 Test method
1.5.1 Tensile property
Preparation of test piece: Stir the sample after standing evenly, pour it into the mold and coat it without mixing air bubbles. In order to facilitate demolding, the mold surface is treated with a mold release agent. The test specimens were coated twice in preparation, with the interval between the two coatings being 24 h. The thickness of the coating film was 1.2 to 1.5 mm within 24 h. The prepared test specimens were cured for 96 h under standard experimental conditions. Dry in a (40 ± 2) ℃ drying oven for 48 h, and then remove it for more than 4 h under standard experimental conditions. During the performance test, the appearance of the coating film should be checked. The surface of the test piece should be smooth and free of obvious bubbles. Then according to the shape of dumbbell shape Ⅰ in accordance with GB / T 528, the tensile properties are tested in accordance with the relevant requirements of JC / T 864-2008 “Polymer Emulsion Waterproof Coatings”.
1.5.2 Water absorption rate
Three sheets of 100 mm × 25 mm rectangular specimens were cut out from the prepared coating film and the mass record was measured as m0 with an accuracy of 0.01 g. Place the sample in water so that the sample contacts the water as much as possible. The masses of the samples were weighed after 1 d, 3 d, and 5 d, and recorded as m0, m0, and m2 to the nearest 0.01 g. Calculated according to the formula water absorption W = (m-m0) / m0 × 100%.
1.5.3 Contrast rate
Use a 100 μm wire rod to scrape a coating film on a black and white cardboard to maintain it for 24 hours in a standard environment. Then use a whiteness tester to test the black part of the cardboard, and get 5 values ​​and take the average Δb. The white portion of the paper gives Δw. Contrast ratio according to the formula = Δb / Δw × 100%. 1.5.4 Resistance to staining Use a 120 μm wire rod to scrape a film on a high-density board for 24 hours at room temperature, then use an 80 μm wire rod to scrape a second film for 120 hours at room temperature, and then measure it with a reflectance meter. After the reflectance, brush the mixture of water and fly ash of the same quality (± 0.2 g) on ​​the density board, put it in an oven at 50 ℃ for 30 minutes, and then rinse at room temperature for 2 hours, then flush the water, and perform the second cycle after 24 hours. After waiting for the surface to dry, use the reflectometer to measure the reflectance again, and calculate the stain resistance based on the data.

2 Results and discussion
2.1 Effect of powder mix ratio on tensile properties
As can be seen from Table 4, this product has excellent elasticity and extremely high elongation, far exceeding the standard requirement of 300%. Comparing Formula 1 and Formula 2 of different calcium mesh powders, it can be seen that the filler with a fine particle size helps to improve the strength of the product system. This is because the specific surface area of ​​325 mesh heavy calcium is smaller than that of 800 mesh heavy calcium and the oil absorption is small. In the process of the product, under a certain pigment binder ratio condition, the fine powder can be sufficiently dispersed in the latex molecules of the system In order to form a dense network cross-linking, the waterproof film formed by it has excellent tensile properties.

Effect of powder mix ratio on untreated tensile properties

2.2 Effect of powder mix ratio on water absorption It
can be seen from Table 5 that the water absorption of the product is higher, and the water absorption gradually increases with the longer soaking time. However, different powder combinations have different water absorption rates. When mica powder is generally used in coatings in the form of scales, its horizontal arrangement in the coating can prevent ultraviolet radiation to protect the coating film, and can improve the water resistance of the coating film and enhance the adhesion between the coating film and the substrate, so it absorbs water. The rate is the lowest compared to other powder combinations. Talcum powder is a mixture of two types of structures: flaky and fibrous. The flaky structure can improve the shielding effect of the coating film and reduce the penetration of moisture to the coating film, so its water absorption rate of the formula system is centered.

Effect of powder ratio on water absorption performance

After 7 days of immersion in water, the product’s strength decreases rapidly, and the elongation also decreases to varying degrees (see Table 6). This is caused by the swelling of the product. The water absorption rate of this product has risen once, such as long-term immersion in water Will have a great impact on product performance.

Effect of Powder Proportion after Soaking in Water for 7 Days on Tensile Properties

2.3 Effect of powder mix ratio on waterproof coating contrast ratio It
can be clearly seen in Table 7 that adding a small amount of titanium dioxide to the powder system can effectively improve the contrast ratio of the product. This is because titanium dioxide is the strongest tinting power among white pigments, and has excellent hiding power and tinting power. Therefore, the addition of titanium dioxide in the formulation system can improve the hiding power of the product and the product coverage. .

Effect of powder ratio on ratio performance

2.4 Effect of powder mix ratio on stain resistance of coating
As can be seen from Table 8, the best stain resistance is Formulation 2. Adding talc, calcined kaolin, and mica powder have poor stain resistance, and the stain resistance of these formulas is basically different. In this experiment, only the heavy calcium in the formula was the best anti-staining performance of the pigment and filler formula, and the 800-density heavy calcium with the better density was the best. Therefore, when other properties of the product are similar, calcium powder with a fine particle size can be selected as the main filler to improve the stain resistance of the product.

Effect of powder ratio on stain resistance

3 Conclusions
One-component acrylic waterproof coating has been widely used in waterproofing and decoration of buildings. By using excellent acrylic emulsion as the base material, it has the characteristics of high elasticity, durability, and good bonding strength. Experiments show that the mix of different powders and powders has a certain degree of influence on the tensile properties, water absorption, and stain resistance of waterproof coatings. At the same time, according to the performance of this product, it has excellent characteristics:
(1) from In this performance study on the single-component acrylic waterproof coating, it can be found that the product has a higher elongation, far exceeding the standard of 300%, and can adapt to some deformation of most building structures.
(2) From the product application From the point of view, this product is a single component, ready to use out of the bucket, convenient construction, saving time and effort.
(3) Because this product is a water-emulsion waterproof coating, which meets the requirements of today’s environmental protection, the choice of different powders still has a high impact on the water absorption of this product. Although this product has excellent water resistance, according to this product, In the experiment, the water absorption rate is high, and it is not suitable for long-term immersion in waterproof engineering projects.
(4) The composition of different powders has a significant impact on the stain resistance of the product. If the product is used for exposure, choose a powder combination with better stain resistance as much as possible. If heavy calcium powder is selected, it has excellent stain resistance, which helps to improve the durability and color retention of the product.
(5) While maintaining the excellent stain resistance and durability of the product, a certain amount of titanium dioxide must be added to the powder to increase the contrast ratio of the product and increase the product coverage.
In summary, the single-component acrylic waterproof coating is a special environment-friendly waterproof coating. In the process of product preparation, the combination of different powders needs to be considered to achieve the best product performance.

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