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    Home > Coatings News > Paints and Coatings Market > The effect of the stretching performance of the waterproof coating of polymer emulsion building was studied

    The effect of the stretching performance of the waterproof coating of polymer emulsion building was studied

    • Last Update: 2020-12-23
    • Source: Internet
    • Author: User
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    Polymer emulsion building waterproof coating (hereinafter referred to as waterproof coating), is based on polymer emulsion, supplemented by fillers and other additives prepared from a single component of water milk waterproof coating, with high and low temperature resistance, high fracture elongation characteristics, can effectively alleviate the leakage caused by the grass-roots subsidon cracking, can be widely used in toilets, kitchens, floors, balconies and non-exposed roof waterproof and moisture-proof treatment. Its film-forming mechanism is: waterproof coating after coating in a decentralized state of polymer particles and filler particles gradually close, with the evaporation of water, polymer particle surface adsorption layer gradually by irreversible damage, and form a build-up, under the influence of late capillaries, polymer particles began to deform, at the same time, polymer interface molecular chain diffusion, penetration, winding to further improve the performance of the paint film, forming a continuous film with a certain performance. In addition to the main gel raw material polymer emulsion, fillers also play an important role in waterproof coatings

    .
    This paper discusses the effect of the type of filler and the number of sights on the tensile performance of the waterproof coating of polymer emulsion building under the same emulsion/filler quality ratio, and studies the compounding effect between the two fillers, and selects the more economical and practical filler types and objectives with the best performance.fillers: 325, 800 and 1,200 purpose quartz powder, 800 purpose heavy calcium carbonate, 800 purpose kaolin, 800 purpose sedimentation of nihric sulfate, the above powders are commercially available.preparation of the polymer
    the polymer emulsion building waterproof coating as shown in Table 1. The preparation method is as follows: in accordance with the quality of the formula first add emulsion, water, de bubble inhibitor, dispersant, stirring at 500r/min speed 5min, then add titanium dioxide and filler and adjust the speed to 800 r/min stirring 20 min, to filler dispersed evenly after adding preservatives, slow stirring 5 min remove the air bubbles in the coating to obtain polymer emulsion building waterproof coating.
    2 Results and discussion of the impact of
    2.1 fillers on the tensile performance of waterproof coatings
    precipitated sulphate, quartz powder, heavy calcium carbonate, kaolin as fillers, respectively, according to the formula of Table 1 to make polymer emulsion building waterproof coating, according to the standard method of coating, maintenance, and make the corresponding test samples, and then carry out the corresponding test strength and fracture extension test. The results of the test results of the stretching performance of the water-resistant paint film, which are untreated and have been heated, alkali-treated and acid-treated respectively, are analyzed and compared to study the effect of different fillers on the stretching performance of the waterproof coating.
    2.1.1 Stretching performance of untreed waterproof paint coating film
    several polymer emulsion waterproof coatings were prepared under the same emulsion/filler quality ratio and the same number of filler items, comparing the tensile performance when the waterproof coating coating film prepared by different fillers was not treated. The test results are shown in Figure 1.
    can be seen from Figure 1, the water-resistant paint film prepared by different fillers, its fracture elongation is inversely inversely related to the tensile strength, i.e. the coating film tensile strength with a large fracture elongation is small. The pull strength of the waterproof paint film prepared with precipitated sulphate as a filler is low, while the softness of the waterproof paint film prepared with kaolin as a filler is poor, and the water-resistant coating of polymer emulsion with fracture elongation and stretch strength performance is greater with quartz powder or heavy calcium as filler.
    From the oil absorption value analysis, the amount of oil absorption of fillers has a greater impact on the performance of the paint film, in the process of coating film drying, polymer molecules not only completely covered the surface of the filler particles, but also need to fill the gap between particles. In the coating system, when the filler absorbs a large amount of oil, more polymer molecules are needed to complete these functions, resulting in the polymer emulsion is dispersed phase, the filler is continuous phase, the coating film is rigid. The suction value of the four powders, sulphate, quartz powder, heavy calcium carbonate and kaolin, increased in turn, so the extrusion strength of the waterproof paint film prepared as a filler increased in turn, and the fracture elongation rate decreased in turn.
    2.1.2 The extrusion performance of the treated waterproof paint film
    According to the standard JC/T 864-2008 indicator requirements, the water-resistant paint coating film after heat treatment, alkali treatment, acid treatment fracture elongation rate of not less than 200%, after heat treatment, alkali treatment and acid treatment paint film extrusion strength hold rate of 80%, 60% and more than 40%, respectively. Figure 2 and Figure 3 are the results of the stretching performance test of the waterproof coating prepared with different fillers.Through the treatment of waterproof paint and non-treated waterproof paint stretch performance comparison can be seen, with the same kind of filler prepared waterproof paint film, after heating treatment of the fracture elongation rate than when no treatment slightly decreased, but the stretch strength significantly increased. This is mainly because the polymer emulsion building waterproof coating formula does not contain plasticizers and film-forming additives and other heat-prone volatile components, the system is stable, so the fracture elongation rate is stable, and after heating treatment of dry film, the coating system of the original stable polymer molecules and filler particles will be further combined, so that the binding force between the two increases, resulting in an increase in the tensile strength of the polymer.
    As can be seen from Figures 2 and 3, after alkali treatment and acid treatment, the fracture elongation rate of waterproof coating obtained by precipitation of niacin sulfate and quartz powder as fillers has increased to a certain extent, the stretch strength decreased, but the stretch strength hold rate is about 70%. The main reasons for the change in the performance of the force are: although niacin and quartz powder do not react with acid-base anti-biochemical reaction, but as a filler prepared waterproof coating dry film in the lower concentration of acid or alkali solution have a certain water absorption rate, dry during immersion process The volume of the membrane will expand slightly, flexibility will be enhanced, the inter-molecular force will be reduced, which will lead to the coating film's fracture elongation rate increased, the stretch strength decreased; Molecules can not completely cover calcium carbonate particles, can not play the role of protecting collosomes, when the heavy calcium carbonate for fillers prepared waterproof coating immersed in a low concentration of sulfuric acid solution, sulfuric acid and calcium carbonate reaction to produce CO2 gas, resulting in The network structure formed between polymer molecules and filler particles is destroyed, the soaked dry film expands and even foams, so the waterproof coating with heavy calcium carbonate as a filler has been treated with alkali and its fracture elongation rate has increased, and the stretch strength hold rate has decreased slightly. After acid treatment, its fracture elongation rate and stretch strength hold rate are very low, the polymer emulsion building waterproof coating prepared with kaolin as a filler after alkali treatment and acid treatment stretching performance is low, in addition to the dry film itself is absorbent, kaolin itself contains a small amount of Al2O3, in the process of soaking acid-base will react, resulting in poor acne after acid-alkali treatment. Through the above performance comparison, it is found that the waterproof coating prepared with quartz powder as a filler has both strength and flexibility, the non-treated waterproof coating stretching performance is good, and the water resistant coating stretching performance after treatment is excellent.
    2.2 Effect of the number of filler items on the tensile performance of waterproof coatings
    For example, the effect of 325, 600, 800 and 1,200 quartz powders on the performance of coating film is shown in Figure 4.
    From Figure 4, it can be seen that with the increase in the number of filler items, the tensile strength of the polymer emulsion building waterproof coating gradually increased, the fracture elongation rate gradually stabilized after rising to a certain extent, because when the number of fillers is low, the corresponding particle size is larger, resulting in large gaps between particles, can not form a stable network structure with polymer molecules, waterproof coating dry film surface rough, can not form a dense membrane structure, so the fracture elongation and tensile strength are lower. When the number of filler items increases and the particle size of the corresponding powder becomes smaller, the polymer molecules can evenly cover the powder particles, so that the filler can be evenly dispersed as a dispersion phase in the continuous phase of the emulsion, resulting in improved coating properties. Because the flexibility of the coating film is mainly provided by the polymer emulsion, therefore, when the amount of polymer emulsion in the formulation system is unchanged, the mechanical properties of the waterproof coating prepared by the fillers of different numbers will stabilize after reaching the upper limit, and the tensile strength will increase slightly. Therefore, in order to obtain a good performance of polymer emulsion building waterproof coating, the formula should choose between 600 to 800 quartz powder as a filler.
    2.3 Effects of filler re-pairing waterproof coating stretching performance
    The use of different filler compounds can compensate for the use of a single filler defect, resulting in improved stretching performance of waterproof coatings. The effects of heavy calcium carbonate, quartz powder, precipitated palladium sulfate and kaolin as fillers on the stretching performance of prepared waterproof coatings are discussed, and it is found that although heavy calcium carbonate is cheap, the acid resistance of waterproof coatings obtained as fillers is very poor, the fracture elongation rate after acid treatment does not meet the standard requirements, and the precipitation of sulfuric acid is good because it is an inert filler, and the resistance of the waterproof coating obtained by it is good. Therefore, through the heavy calcium carbonate and precipitated sulphate compounding as a filler waterproof coating formulation system, polymer molecules can completely cover the heavy calcium carbonate particles, while improving the acid resistance of the coating film, so that the acid-treated waterproof coating fracture extension rate reached the standard requirements. By studying the effect of the mass ratio of heavy calcium carbonate in the total filler dosing on the extruded performance of the waterproof coating after acid treatment, the compounding effect of the two fillers is analyzed, and the results are shown in Figure 5.
    From Figure 5, it can be seen that with the increase in the quality ratio of heavy calcium carbonate in the formula, the fracture elongation rate of the polymer emulsion building waterproof coating after acid treatment decreased, the stretch strength hold rate decreased and the mechanical performance decreased;
    3 Conclusion
    1) Filler as an important part of the polymer emulsion building waterproof coating formula, in the case of emulsion / filler quality ratio, the greater the suction value of the selected filler, the greater the stretch strength of the waterproof coating, the smaller the break elongation;
    2) For the same filler, the number of items of the filler is too small, will lead to the resulting waterproof paint film structure is not dense, fracture elongation and tensile strength are low, and the number of items of the filler increased to 600 eyes and above, the number of items on the stretch performance of waterproof coating is less.
    3) waterproof coating prepared with 600 to 800 quartz powders for fillers has excellent stretching performance, and can improve the stretching performance of waterproof coatings through different filler compounding, with a ratio of no more than 75% of heavy calcium carbonate compounding sulphate as a filler, can be made economical, practical, good performance of polymer emulsion building waterproof coating.
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