YA NG Jing-xin91，CHEN Bing-ya02,YA 0 Rong-ma01，LUO Guo—ta01
(1．Guangdong Shunde Sanvo Chemical Co．，Ltd．，Foshan 528325，Guangdong，China； 2．Guangdong Sanvo Chemical Industry Technology Co．，Ltd．，Zhongshan 528429，Guangdong，China)
Abstract：Waterborne fluorine coatings not only have the traditional excellent properties of high hardness，weather resistance and stain resistance，but also have good water solubility in hydrophilic materials，which is in line with the environmental protection developpment concept of modern building materials market．Currently in the fields of machinery，aviation and construction．Waterborne fluorine coatings are new materials in the field of coatings．Various technologies are still in the exploration stage，and the gloss of the paint film fluctuates greatly during the production process．This experiment compared the types of waterborne fluorine coating fillers，pigment volume concentration(PVC)，the amount of dispersant，the type of thickener and the type of filming aids，and summarized the techniques to effectively ensure the gloss stability of waterborne fluorine coatings．
Waterborne fluorine coatings have excellent properties such as good weather resistance, stain resistance, water resistance In addition, it also has the characteristics of environmental protection, so it is getting more and more attention . With the development of China ’s national economy and the improvement of people ’s living standards, in addition to putting higher requirements on the basic functions of coatings, people have also paid more attention to the appearance of coatings. The gloss of the coating film is an important indicator of the appearance of coatings. One is the ability of the surface of the coating film to reflect the light shining on it in one direction. Generally speaking, the gloss of latex coatings can be roughly divided into four grades of light, semi-gloss and mercerized (egg shell light) and flat light (see Table 1) .
There are many factors that affect the gloss of latex coatings, which can be roughly divided into internal factors (the performance of the coating itself) and external factors (such as the construction environment and the flatness of the substrate). This article mainly studies the internal factors, namely the properties of the coating itself, including the type of filler, the amount of dispersant, the pigment volume concentration (PVC), the type of thickener and the type of film-forming aids on the gloss of water-based fluorine coatings.
2 Experimental section
2.1 Main raw materials
Fluoro resin emulsion (F500-1), Dalian Zhenbang; pigments and constitutional pigments are both commercially available; various coating special additives are commercially available.
2.2 Reference formula
See Table 2 for reference formula of paint.
2.3 Preparation of
paint First add quantitative deionized water to the paint mixing tank, and then add dispersant, wetting agent, defoaming agent, antifungal preservative, and co-solvent in order while stirring. Add the pigments in order after stirring And filler, disperse at high speed, and sand to the specified fineness; transfer the milled white slurry to the base tank weighed in a stirred state through filtration, and then add the remaining film-forming aids, defoamers, Thickener, rheological agent, pH adjuster, stir well before use.
2.4 Determination of gloss
Using WGG 60 gloss meter.
The coating was coated on a clean glass plate with a wet film preparation device with a size of 100 mm, and dried at (23 ± 2) ° C and a relative humidity of 50% for more than 48 hours to obtain a flat coating film. After adjusting the instrument and calibrating, three readings were measured at three different positions of the pre-made test plate. If the relative error of the result is less than 5%, calculate the average value as the result.
3 Results and discussion
3.1 Effect of filler types on coating gloss (see Table 3)
Note: PVC is 32%, film-forming aid is alcohol ester-12, thickener is DSX 3116, and dispersant dosage is 0.8%.
As can be seen from Table 3, the degree of influence of different fillers on gloss is different. Among them, precipitated barium sulfate has the least effect on gloss, which indicates that it has good optical properties. The addition of other fillers, such as heavy calcium powder, talc, and kaolin, greatly reduces the gloss. Kaolin clay has the largest reduction in gloss, indicating that its optical properties are poor and it has a significant matting effect.
3.2 Effect of pigment volume concentration (PVC) on gloss of paint The effect of
pigment volume concentration on gloss of paint is relatively large, and the gloss of paint gradually increases with the decrease of PVC, see Table 4. This is because when the PVC is large, the emulsion cannot completely cover the pigments and filler particles, and some pigments and fillers are exposed outside during film formation. The formed coating film is relatively rough, and the light scattering is serious, so the gloss is low. With the decrease of PVC, the emulsion can cover the pigment and filler particles, and the resulting coating film is dense and smooth, so the gloss gradually increases.
3.3 Effect of the amount of dispersant on the gloss of the coating (see Table 5)
Note: 30% of PVC, 26% of titanium white, no filler, thickener DSX 3116, and film-forming aid is alcohol ester-12.
It can be seen from Table 5 that as the amount of dispersant increases, the gloss of the coating also increases. When it increases to 0.8%, the gloss remains basically unchanged. This is because before the optimal amount of dispersant is reached, as the amount of dispersant increases, the degree of dispersion of pigments and fillers can be increased, so that the formed coating film is more flat and smooth, and the gloss is correspondingly increased. When the dispersant is increased to the optimum amount, the dispersion degree of the pigment and filler has reached the best. Therefore, if the dispersant amount is further increased, the gloss will no longer be improved.
3.4 Effect of thickener types on paint gloss
Thickener types have a certain effect on paint gloss, but the degree of influence is not significant (see Table 6). Of the four thickeners used, DSX2000 has the best results, followed by associative thickener DSX 3116, and finally hydroxyethyl cellulose HBR 250 and alkali-swelling thickener DSX1130. This is because the rheology modifier DSX 2000 has better leveling performance and can compensate for the surface defects of the coating film to a certain extent. The resulting coating film is smooth, smooth and uniform, so the gloss is the highest. The associative thickener DSX 3116 also has good rheological properties, but is inferior to DSX 2000, so the gloss is second. In contrast, the thixotropy of alkali swelling thickener DSX 1130 and hydroxyethylcellulose is quite large, which makes the leveling property of the coating poor and cannot compensate for the defects of the coating film, so the coating gloss is also the lowest.
3.5 Effect of film-forming additives on coating gloss (see Table 7)
As can be seen from Table 7, due to the different types of film-forming aids used, the gloss of the resulting coating film also varies to some extent. The gloss of the coating using alcohol ester-12 is obviously higher than that of the other two film-forming aids. This is mainly because the alcohol ester-12 has good compatibility with the fluororesin emulsion, making the polymer soft and dense. Smooth coating. Therefore, it is very important to choose the proper film-forming aid.
(1) The addition of fillers will reduce the gloss of water-based fluorine coatings. Different fillers have different degrees of influence on gloss. Among them, precipitated barium sulfate has the smallest effect on the gloss of paint, while kaolin, talc, etc. have a greater impact on gloss and have a greater matting effect.
(2) The gloss of the coating is greatly affected by PVC. As the PVC decreases, the gloss of the coating increases correspondingly.
(3) The amount of dispersant has a certain effect on the gloss of water-based fluorine coatings. When the amount of dispersant is 0.8%, the gloss of the coating is the highest.
(4) The better the leveling performance of the thickener, the higher the gloss of the coating.
(5) The compatibility of the film-forming aid with the fluororesin emulsion has a greater impact on the gloss of the water-based fluorine coating. The better the compatibility, the fewer defects in the coating film formed, and the higher the gloss of the coating film.