Study on Influence Factors of Scrub Resistance of Latex Paint

CHENG Liang-yu, HUANG Ning
(Foshan Shunde BATF Industry Co., Ltd., Foshan 528322, Guangdong, China)

Abstract: The paper mainly studies the factors affecting scrub resistance of interior walls, including the effects of powder,additive and emulsion feeding points on scrub resistance. It aims to providing data support and assistance for stage wise inspection of scrub resistance of interior walls and for improvement of the performance of interior wall latex paint.

0 PrefaceChina has become the country with the largest coating production and demand in the world. Among them, architectural coatings account for more than 1/3 of the market share, and latex paints have gradually become the leader in architectural coatings. With the rise of the price of coating raw materials, various high PVC (pigment volume concentration) latex coatings are constantly emerging. In the design of high PVC interior wall latex paint, scrub resistance is the focus of attention because it often affects the adhesion, durability, water resistance and other properties of interior wall latex paint films. The scrub resistance of latex paint refers to the ability of the coating film to withstand repeated washing by a brush dipped in a washing medium (0.5% washing powder water) without damage. Because the main factor that affects the scrub resistance of latex paints is the adhesion of the coating film, and the film-forming substance that provides the film’s adhesion in latex paints is emulsion, and PVC and CPVC (critical pigment volume concentration) in latex paints. It is directly related to the performance of the coating film. The additives also have a great influence on the film formation and coating performance of the coating. Therefore, the influence of the above factors on the scrub resistance of the coating film should be considered in the design of the interior wall emulsion paint formula. The method for testing the scrub resistance of latex paint refers to the ability of the paint film of the latex paint to withstand repeated scrubbing on the JTX-Ⅱ architectural coating scrub resistance meter without being damaged by being dipped in a washing medium (0.5% washing powder water). This technical index is very important for interior wall coatings, and its quality is directly related to many properties such as the adhesion, stain resistance, and durability of latex paints. The national standard GB / T 9756-2001 also has resistance to interior wall latex paints. Clear requirements for scrubability. The type and amount of the emulsion are the most important factors affecting the scrub resistance of the latex paint. The purpose of this article is to explore the influence of powders and additives on the scrub resistance of interior wall emulsion paints. Through this study, the scrub resistance of interior wall emulsion paints can be improved, and a classification test for the scrub resistance of interior wall emulsion paints can be formulated. , To promote the development of interior wall latex paint.

1 Experimental part

1.1 Experimental equipment and materials

SFJ-400 Sanding, Dispersing, Stirring Multi-purpose Machine, JTX-II Architectural Coating Scrubber, SZQ-200-ISO, Shanghai Modern Environment Engineering Technology Co., Ltd .; Asbestos Cement Pressure Plate, 50 mm × 70mm × 4.5 mm, Guangzhou Biaogeda Laboratory Instrument Supplies Co., Ltd .; Electronic Balance ES3200, Frequency Oscillation Instrument Co., Ltd .; 250HBR, Ashland; AMP-95, The Dow Chemical; SN-5040, San Nopco; LN- 407, Guangdong Shunde Shibang Jiaming Chemical Co., Ltd .; Defoamer 117, Nanjing Shengdao Environmental Protection Products Factory; Rutile Titanium Dioxide R-706, DuPont; 800 mesh heavy calcium, Guibao Co., Ltd .; Calcined Kaolin DB-80, Shanxi Jinyang Calcined Kaolin Co., Ltd .; Washed Kaolin, Mankat Co., Ltd .; Fungicide GT-50, Germany Blue Chemical Co., Ltd .; Film-forming Auxiliary Texanol, Eastman;


1.2 Experimental formula design

First determine a basic formula and adjust various powders and additives on the basic formula, but ensure that the total amount of powders and additives is unchanged. Use this method to study the impact of various powders and additives on scrub resistance. . The basic formula is shown in Table 1.

Basic formula

1.3 Detection methods

(1) Preparation of latex paint: firstly add 240 g of the first part of water into a 1 kg tank, add 250HBR, stir and dissolve with dispersant for 15 minutes (cellulose dissolves, water thickens significantly), and add pH adjuster AMP-95 respectively , Thickener SN-5040, wetting agent LCN-407, antifoaming agent 117, after uniform dispersion, add titanium dioxide R-706 for 25 minutes, then add other powders for 30 minutes, and finally add the fungicide GT-50 , Emulsion, second part of defoaming agent 117, film-forming aid, antifreeze EG, second part of water. All formulas were operated according to this procedure, and 13 different latex paints were prepared.(2) Preparation of coating film: The film was scraped on a non-asbestos fiber cement pressure plate with a 200 μm wet film preparation device. The same variables were compared with each other. Each comparison was done twice. In order to reduce the error, these two comparisons The left and right positions of the two samples will be changed, and the test plate will be cured at room temperature for 7 days.(3) Scrub resistance test: Install the cured test panel on the architectural paint scrub resistance instrument, and ensure that the two panels with the same comparison sample are washed under the same brush, and each test 200 times, add 2 test tubes of 0.5% washing powder water. When the coating film is broken to the middle position of the sample, the number of scrubbing times is recorded.


 2 Scrub resistance test results and discussion

The design experiment was carried out by changing the addition amount of various powders and additives. Test samples ①, ②, and ③ are m (titanium dioxide): m (heavy calcium) are 0: 340, 80: 260, and 120: 220, respectively; test samples ④, ⑤, and ⑥ are m (calcined kaolin): m (weight Calcium) are 0: 400, 50: 350, 150: 250 respectively; the test samples ⑦, ⑧, ⑨ are m (washed kaolin): m (heavy calcium) ratios are 0: 350, 100: 250, 150: 200 ; The test samples ⑩, ⑪, ⑫ are m (heavy calcium): m (titanium dioxide) are 0: 340, 100: 240, 200: 140, and others are consistent with the basic formula. Test samples a, b, and c are SN-5040 of 0 g, 9.0 g, and 13.5 g, respectively, with a total amount of less than 1,000 g, or more than 1,000 g, adjusted from the first part of the water in the basic formula to a total of 1,000 g. Other components remain unchanged; test samples d, e, and f are adjusted to 0 g, 1.6 g, and 2.4 g of LN-407, respectively, and the total amount is adjusted to 1,000 g in the same manner as test samples a, b, and c; test sample g , H, i adjust the film-forming aids to 0 g, 4 g, and 12 g, respectively, and adjust the total amount to 1,000 g; test samples j, k, l adjust the EG amount to 0 g, 5 g, and 15 g, and adjust the same The total amount is 1 000 g.2.1 Effect of powder on scrub resistanceTable 2 Formulas ①, ②, ③, ⑩, ⑪, and ⑫ are for changing the ratio of 800 mesh heavy calcium and titanium dioxide, and formulas ④, ⑤, and ⑥ are for changing the ratio of calcined kaolin and 800 mesh heavy calcium. The formulas ⑦, ⑧ , ⑨ is to change the ratio of washed kaolin and 800 mesh heavy calcium. Because it is necessary to ensure that the amount of powder is consistent, while changing other powders, the corresponding 800 mesh weight calcium with a large amount of change is known from Table 2 ③ > ② > Basic > ①, ⑫ > ⑪ > Basic > ⑩. From this result, it can be seen that when the titanium dioxide and 800 mesh heavy calcium are in the formula ③ ~ ⑫, the scrub resistance is very good, because the 800 mesh heavy calcium particles can be used as a skeleton, while the titanium dioxide particles are small and have a filling effect [4], Only 800 mesh heavy calcium and filled titanium dioxide, which acts as a skeleton, can play a firm role at the proper ratio, and the scrub resistance will be good. Basis> ④, ⑤, ⑥. From the data in Table 2, it can be seen that changing the calcined kaolin and 800 mesh heavy calcium has little effect on scrub resistance. ⑦> Basic> ⑧> ⑨, it can be seen from Table 2 that the higher the ratio of washed kaolin, the worse the scrub resistance.

Scrub resistant results with different powder formulations

2.2 Effect of additives on scrub resistance (see Table 3)

Under the conditions of the basic formula, the amount of various additives is changed, and the amount of water is replenished to ensure that the relative amounts of other ingredients remain unchanged. Formulas a, b, and c are for adjusting the amount of dispersant SN-5040, formulas d, e, and f are for adjusting the amount of wetting agent LCN-407, and formulas g, h, and i are for adjusting the amount of film-forming additives , Formula j, k, l is to adjust the amount of antifreeze EG added.

Scrub resistance results of different additive formulations

From Table 3 we can see the scrub resistance, a> basic> c> b, so adding SN-5040 will reduce its scrub resistance; d> basic> e> f, with the addition of wetting agent LCN-407 As the amount increases, the scrub resistance becomes worse and worse. From this we can see that the wetting and dispersing agent will reduce the scrub resistance of latex paints, because the wetting and dispersing agent’s hydrophilicity will lead to a decrease in water resistance, and their penetration from the coating film will destroy the coating film, resulting in a decrease in scrub resistance. . i. Basics> h> g, we can see that increasing the amount of film-forming aids will increase the scrub resistance, and from 8% to 12%, the effect is not obvious, so film-forming aids are suitable at about 10% Because the film-forming aid can reduce the film-forming temperature of the emulsion, making the latex paint film denser, the film-forming effect is better, and the scrub resistance can be improved, but too high will not continue to improve scrub resistance. Basis> j, k, l. From this, it can be seen that the anti-freezing agent EG has no obvious effect on abrasion resistance.


 3 Conclusion

(1) The ratio of titanium dioxide to heavy calcium is between 0.55 and 0.7. The scrub resistance is good, and the ratio is too high and too low, which is poor, because 800 mesh heavy calcium particles can be used as a skeleton, while titanium dioxide particles are small and can be used for filling Function, only 800 mesh heavy calcium and filled titanium dioxide, which serve as a skeleton, can play a solid role at the appropriate ratio, and the scrub resistance will be good. Changing the amount of segmented kaolin has no significant effect on scrub resistance, and adding water-washed kaolin will reduce scrub resistance.(2) The addition of dispersant 5040 and wetting agent 407 will reduce scrub resistance. An appropriate amount should be selected for comprehensive performance. The film-forming aid C-12 is never added to 8.9%, and the scrub resistance is significantly improved. Compared to 8.9%, the increase to 13.3% is not obvious, so it is more appropriate to add C-12 at about 10%. The difference between adding different amounts of EG was not obvious.

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