Explore the influence factors of latex paint scrub resistance

0 Foreword
China has become the world's largest paint production and demand of the country, of which, architectural coatings accounted for more than 1/3 of the market share, and latex paint has gradually become the leader in architectural coatings. With the rise in the price of raw materials for coatings, a variety of high PVC (pigment volume concentration) latex coatings continue to emerge. In the design of high PVC inner wall latex paint, scrub resistance is the focus of attention, because it often affects the internal wall latex paint coating film adhesion, durability, water resistance and other properties .
scrubbing resistance of latex paint refers to the coating film's ability to withstand repeated brushing without damage from brushes with washing media (0.5% washing powder). Because the main factor affecting the scrubbing resistance of latex paint is the mucous ability of the coating film, and the film mucous capacity provided in latex paint is mainly film-forming substances - emulsions, in addition, PVC and CPVC (critical pigment volume concentration) in latex paint has a direct relationship with the performance of the coating film, additives on the coating film and coating performance also has a great impact, so in the design of the inner wall latex paint, should consider the above factors on the effect of the coating.
And the test latex paint scrub resistance method refers to the latex paint coating film with washing medium (0.5% washing powder) on the JTX-II. building paint brushing instrument repeatedly washed without damage. This technical index is very important to the inner wall paint, its good or bad is directly related to latex paint bonding ability, stain resistance, durability and many other performance, national standard GB/T 9756-2001 also made clear requirements for the scrub resistance of latex paint on the inner wall.
type of emulsion and how much is added is the most important factor affecting latex paint scrub resistance. The purpose of this paper is to explore the effect of powder and additives on the scrubbing resistance of inner wall latex paint, and through this research, we can improve the scrub resistance performance of inner wall latex paint, and develop a graded test of the performance of inner wall latex paint scrubbing resistance, and promote the development of inner wall latex paint.
1 Experimental part
1.1 Experimental instruments and raw materials
SFJ-400 sanding, dispersion, mixing multi-use machine, JTX-II architectural coating wash-resistant brush, coating preparer SZQ-200-ISO, Shanghai Hyundai Environmental Engineering Technology Co., Ltd.; Asbestos cement pressurized plate, 50 mm×70 mm×4.5 mm, Guangzhou Standard Gerda Laboratory Instrument Supplies Co., Ltd.; Electronic balance ES3200, frequency vibration instrumentation Co., Ltd.; 250HBR, Aschland; AMP -95, Dow Chemical; SN-5040, St. Nopko; LN-407, Shunde Shibang Jiaming Chemical Co., Ltd.; Defoatic 117, Nanjing Sanctuary Environmental Protection Products Factory; Jinhongshi Titanium White Powder R-706, Du Bang; 800 heavy calcium, Guibao Co., Ltd.; calcined kaolin DB-80, Shanxi Jinyang calcined kaolin co., Ltd.; washed kaolin, Mankat Co., Ltd.; fungicide GT-50, Delan Chemical Co., Ltd.; membrane additive Textanol , Eastman; antifreeze EG, Wuxi City Yipeng Science Industry and Trade Co., Ltd.
1.2 Experimental formula design
first determine a basic formula, in the basic formula for a variety of powders and additives adjustment, but to ensure that the total amount of powders and additives remain unchanged, using this method to study the effects of various powders and additives on scrub resistance. The base formula is shown in Table 1.
1.3 Detection Method
(1) Latex paint preparation: First add the first part of the water 240 g in a 1 kg tank, add 250HBR, stir with dispersant to dissolve 15 min (cellulose dissolved, water significantly thickened), respectively, add pH regulator AMP-95, thickener SN-5040 , moisturizer LK-407, defrost 117, to be dispersed evenly after adding titanium dioxide R-706 dispersed 25 min, then added other powder dispersed 30 min, and finally added fungicide GT-50, emulsion, the second part of desosterizer 117, film-forming additives, antifreeze EG, the second part of water. All formulations follow this procedure and 13 different latex paints are prepared.
(2) coating film preparation: with a 200 m wet film preparation in the asbestos-free fiber cement pressurized plate scraping film, the same variable between two contrasts, each comparison done twice, in order to narrow the error, these two contrasts will change two kinds of left and right position, test plate room temperature maintenance 7 d.
(3) Scrub-resistant test: the maintenance of the test board installed on the building paint scrub-resistant instrument, and ensure that the two plates are the same contrasting plate under the same brush wash, each scrub 200 times plus 2 test tube 0.5% of the laundry detergent. Record the number of scrubs when the coating film breaks into the middle position of the sample.2 scrub-resistant test results and discussion
design experiments by changing the amount of different powders and additives added. Test samples (1), (2), (3) m (titanium dioxide) m (heavy calcium) are 0:340, 80:260, 120:220; ), (5), (6) is m (calcified kaolin) m (heavy calcium) 0:400, 50:350, 150:250; 8), (9) for m (washed kaolin) : m (heavy calcium) ratio is 0:350, 100:250, 150:200; 11), (12) for m (heavy calcium): m (titanium dioxide) are 0:340, 100:240, 200:140, the other is consistent with the basic formula. Test samples a, b, c for SN-5040 are 0 g, 9.0 g, 13.5 g, the total amount is less than 1,000 g, or more than 1,000 g from the first part of the basic formula water adjustment to a total of 1,000 g, the other components remain unchanged; 6 g, 2.4 g, the total amount of adjustment is 1,000 g, the same as the test sample a, b, c;
2.1 Effect of powder on scrub resistance
Table 2 formulation (1), (2), (3), (10), (11), (12) is to change the ratio of 800 heavy calcium and titanium white powder, Formula (4), (5), (6) is to change the ratio of calcined kaolin to 800 heavy calcium, formula (7), (8), (9) is to change the ratio of washed kaolin with 800 heavy calcium. Because to ensure that the amount of powder added is consistent, so change the other powder at the same time, the corresponding change in the amount of 800 heavy calcium by Table 2 (3) > (2) > basic > (1), (12) > (11) > foundation > (10). From this result, it can be seen that when titanium white powder and 800 heavy calcium in the formula (3) to (12) scrub resistance performance is very good, because 800 eye heavy calcium particles can act as a skeleton, and titanium white powder particles small, play a filling role, only as the skeleton of 800 heavy calcium and filled titanium white powder in the appropriate proportion, can play a solid role, scrub resistance will be good. Basic > (4), (5), (6), from table 2 data can be known to change calcination kaolin and 800 heavy calcium on scrub resistance performance has little effect. (7) > basic > (8) > (9), by table 2 can be known that the higher the proportion of water washing kaolin, the worse the scrub resistance.
2.2 Effects of additives on scrub resistance (see Table 3)
Under the conditions of the underlying formulation, change the amount added by various additives, the total quality is not enough to replenish the water quantity, to ensure that the relative amount of other ingredients remains unchanged. Formula a, b, c is to adjust the amount of dispersant SN-5040, formula d, e, f is to adjust the amount of wetting agent LCN-407, formula g, h, i is to adjust the amount of added membrane additives, formula j, k, l is to adjust the amount of antifreeze EG.
From Table 3, we can see the scrub resistance performance, a> foundation >c>b, so adding SN-5040 will reduce its scrub resistance> performance>> From this we can see that wetting dispersants will reduce the scrubbing resistance of latex paint, because wetting dispersant hydromassage resistance will lead to reduced water resistance, they penetrate from the coating film will destroy the coating film, resulting in reduced scrub resistance. i, basic >h>g, we can see that increasing the amount of film additives will improve scrub resistance performance, and from 8% to 12%, the effect is not obvious, so film additives in about 10% more suitable, because film additives can reduce the temperature of emulsion film, so that latex paint film more dense, film effect is better, solid can improve scrubbing performance, but will not continue to improve scrubbing performance. The > j, k and l, so it can be seen that antifreeze EG has no obvious effect on anti-scratch.3 Conclusion
(1) Titanium white powder and heavy calcium ratio in 0.55 to 0.7 scrub resistance is good, the proportion is too high and too low are relatively poor, because 800 eyes heavy Calcium particles can act as a skeleton, and titanium dioxide particles small, play a filling role, only as the skeleton of 800 heavy calcium and filled titanium dioxide in the appropriate proportion, in order to play a solid role, scrub resistance will be good. Changing the amount of burning kaolin in the section has no obvious effect on scrubbing resistance, while adding water-washed kaolin will reduce scrubbing resistance.
(2) dispersant 5040, wetting agent 407 will reduce the addition of anti-scrubbing, should be integrated performance selection to add the appropriate amount, film-forming additive C-12 is never added to add to 8.9%, anti-scrub performance improved significantly, increased to 13.3% relative to 8.9% increase is not obvious, so C-12 addition is more appropriate at about 10%. The difference between adding different amounts of EG is not obvious.
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