LIU Xiao-jing, LING Qin, WANG Lei, DONG Zhi-hui (Shijiazhuang Paint Factory, Shijiazhuang 050000, Hebei, China)
Abstract: Raw materials for elastic texture coatings were compared and selected for good flexibility, stain resistance, and easy application. The formula for exterior wall thermal insulation elastic texture coatings was optimized. The product could better match the external insulation system, and successfully solve the small cracks. It also improved the decorative effects and could be widely applied.
As a coating with decorative and special functions, elastic texture coating is more and more popular in the market. Due to changes in the building dry and wet uniform, thermal expansion and contraction, the structure of the settlement and the imperfect construction reasons, almost all the buildings are there different degrees of cracks, these cracks as common construction quality defects, has been plagued by Construction industry today. The appearance of cracks not only affects the aesthetics of the finish, but also can lead to serious consequences such as frost heaving of the wall , corrosion of the reinforcing bars, and decline in heat insulation due to the infiltration of water . In response to these problems, we developed the product in the original texture of the production base of the product, given its flexibility, function, and supporting systems into line perfect, so that it can better carry out the external wall insulation system supporting applications to ensure Engineering Quality.
1 Experimental part
1.1 The main raw materials
Natural texture of sand (30 to 40 mesh, 40 to 70 mesh, 70 to 100 mesh), Hebei; natural sand (20-40 mesh, 40-80 mesh, 80-120 mesh), river North; elastomeric acrylic emulsion, BASF , Shandong, Jiangsu.
1.2 Experimental equipmentQSJ-B type high-speed disperser; QTB type putty flexibility tester; STIK heat storage drying box; Q-LAB xenon lamp aging tester; S / NAT03357 US imported puller.1.3 Reference formulaDetermining an elastic acrylic emulsion film-forming material, other components can therewith match, stable performance, easy construction product formulations. Refer to Table 1 for details.
1.4 Performance testing
Tested according to the reference formula in 1.3, the performance index reached the JG / T 24-2000 (W type) standard. The specific results are shown in Table 2.
In addition to meeting general performance indicators, we also carried out bomb nature feel coating flexibility test. Flexibility is measured in accordance with GB / T 23455—2009 Standard for Flexibility Index Test Methods for Flexible One-Put Exterior Wall Putty. Measurement test results: 50 mm diameter by, and easy construction, as shown in FIG 1.
Among them, the flexibility of the product needs to be specially pointed out. For external wall insulation package is concerned, flexibility is determined that complementary products can achieve an important indicator of the effect of the crack to make up the wall.
1.5 Experimental methods
1.5.1 Flexibility test method
Test under standard conditions: on a tinplate with a size of 50 mm × 120 mm × (0.2 ～ 0.3) mm, apply an elastic texture coating with a thickness of 1 mm . Making three parallel model, under standard experimental conditions to support guard 7 d. Test in accordance with the provisions of GB / T 1748.After the thermal cycle test: Specification of 150 mm × mm × 70 (0.2 ~ 0.3) mm tinplate plate, elastic properties of the coating thickness of 1 mm feel coating. Making three parallel model, 1 d conservation under standard test conditions , the test piece with an edge sealant to seal the continued maintenance 6 d, then immersed into the (23 ± 2) ℃ water 18 h, and then brought out in the (- Frozen at 20 ± 3) ℃ for 3 h, then put in (50 ± 2) ℃ oven for 3 h. 1 cycle of 24 h, was taken after 5 cycles, continue (50 ± 2) ℃ oven for 6 h, then placed in place 6 h under standard experimental conditions, according to the 1748 rules GB / T given test .
1.5.2 Mechanical stability test method
The prepared paint-like elastic texture, taking 1 kg is placed in a 1 L capacity reactor. And then on a high speed disperser high agitation speed reached 2 000 r / min, continuous observation of the state of the product tank, until a situation thickens case, the recording time under stirring. By determining the length of stirring time to machine the merits of mechanical stability.
2 Results and analysis
2.1 Gradation of colored sand
Different specifications of colored sand show different board surface effects, and different additions have different effects on the board surface. The specific experimental data are shown in Table 3.
The difference between ordinary colored sand and textured sand lies in the effect on the board surface and batch scrapability . The texture of sand is round, the construction is smooth, and the surface of the board is clear and smooth. Using texture sand can get a good texture effect. The texture sands of various specifications should be reasonably matched and filled with each other to improve the surface effect. The specific mix should be based on the customer’s requirements for the surface effect.
2.2 Selection of emulsion
Selection of different manufacturers elastic acrylic emulsion, stick resistant product fouling and flexibility tests, as shown in Table 4.
By comparing experimental data, it can be seen that the elastic acrylic emulsion d has good flexibility characteristics and flexibility durability.
2.3 Selection of additives
Among them, Eastman TEXANOL, which has excellent stability and purity in all aspects, is used as the film-forming aid . The auxiliary film-forming aid is environmentally friendly propylene glycol. Therefore, selective aid experiment mainly for thickening body be based. The specific comparison is shown in Table 5.
Taken together, the final choice man of two thickening system with the use of the case. Cellulose and alkali swelling and thickening agent have a better effect.
Through the above screening experiments of colored sand, emulsion and additives, the type of raw materials selected was determined . The (+ water + Emulsion various additives) known as plasma feed components, the remaining components of the aggregate, the aggregate component and the slurry through a determined ratio of the base formulation components the experiment (Table 6).
Based on the results of the above comparative experiments, experiment two was selected as the basic formula.The surface effect is mainly the grainy effect of textured sand, which needs to be adjusted in the mix of aggregate components. After verifying the construction effect with different texture sand ratios , the best combination is: texture sand 30 ~ 40 mesh accounted for 6% ~ 7%, 40 ~ 70 mesh accounted for 50% ~ 55%, 70 ~ 100 mesh accounted for Than 40% to 45%. But when designing the formula, we must first consider the board surface effect required by the customer . The selection of the texture sand specifications can be adjusted.
3 Supporting applications
Application of any product, there must be appropriate to reflect their support of this value itself, therefore, supporting the overall performance of the film is the perfect embodiment. After more than 4 years of simulation tests and practical application, the best supporting system for external wall thermal insulation was obtained . The parameters of each supporting product are shown in Table 7.
The matching measures adopted in the two communities listed in Figure 2 are: external wall external insulation system → high elastic anti-cracking putty → alkali-resistant closed primer → elastic texture paint → varnish. So far, the slab surface of the exterior wall is good, without cracking, peeling, fading and other problems.
In today’s society that advocates a low-carbon life, the promotion of building energy efficiency is a new challenge for architectural coatings. Architectural coatings must adapt to the performance requirements of the external insulation system, and have a good complementarity with the thermal insulation materials to achieve the perfect unification of protection and decoration effects. Elastic texture coating selected from elastic acrylic emulsion as a film-forming substance, with the external security can better match the temperature system, to compensate for problems caused by cracking the wall of the small cracks. Through continuous efforts and improvements, elastic texture coating will be excellent performance, complete beauty package, widely used in cement walls and exterior insulation system, a unique decorative effect to beautify people’s living environment.