Comprehensive performance detection of titanium dioxide in powder coatings

Titanium dioxide is one of the most commonly used pigments in powder coatings and is one of the strongest coloring forces in white pigments, with excellent masking power and coloring fastness. With the rapid growth of titanium dioxide production, the market for powder with gold and redstone brand also surge, in view of the price of titanium white powder is more expensive, the use of large, and the quality of titanium dioxide on the market is uneven, some manufacturers in order to pursue profits at all costs mixed with other fillers. How to do a good job in the testing and evaluation of titanium dioxide, strengthen quality control, improve the quality of powder products, it is particularly important.1, titanium dioxide purity determination
titanium dioxide mainly has two different structures - sharp titanium type and redstone type, the term powder coating titanium dioxide in addition to providing color, there is a very important role, absorbing ultraviolet light to provide the weather resistance of the coating. The photogenic activity of gold-redstone-type titanium dioxide is lower than that of gold-redstone type, the efficiency of absorbing ultraviolet light is higher than that of sharp titanium type, its weather resistance is much higher than that of sharp titanium-type titanium white powder, and the powder coating is mostly gold-redstone-type titanium white powder. Therefore, for the test of the purity of titanium dioxide, there are two aspects: first, the content determination of TiO2 in titanium white powder;
the content of TiO2 in 1.1 titanium white powderPrinciple
The heating of sulfuric acid and ammonium sulfate dissolves, resulting in titanium ions and H2O2 to produce TiO (H2O2) oxygen titanium-based compounds, which are not easily hydrolysed and can still be combined with EDT after adding EDTA TA forms a 1:1 compound, with a pH of 1.0-2.0 acidity, with methanol orange as an indicator, using nitrate back to drop excess EDTA, so as to measure the content of titanium.reagent
0.025MEDTA standard solution
0.015M nitrate solution
1:1 ammonia
1:20 nitric acid solution
30% H2O2 solution
0.2% methotrexol Orange solution
healthy sulfate
ammonium sulfatesteps
said to take about 0.4 titanium dioxide and beaker, add 25 to 30 ml of thick sulfuric acid, 10 grams of ammonium sulfate, electric furnace heating dissolved, moved into 250 ml capacity bottle, water dilution to scale, shake.
5 ml of the above solution in 250 ml conical bottle, add 5 drops of 30% H2O2, then add 10 ml of 0.025MEDTA standard solution, add water to 150ml, with 1 :1 ammonia regulation PH value between 1.0 and 2.0, drop 4 to 5 drops of methanol orange indicator, with 0.015 nitrate drop to change from yellow to red, that is, the end point.calculation formula
formula (1)
V-EDTA standard solution added to the number of milliliters;
.V1 - Nitrate added milliliters;
.TTiO2 - 1 ml of EDTA standard solution equivalent to the number of milligrams of titanium dioxide;
.G . . sample weight, g;
.a .
a calculation: nitrate standard solution and EDTA standard solution volume ratio
accurately absorb 10 ml 0.025MEDTA standard solution, placed in 250 ml berries, diluted with water to about 150 ml, drip plus 1: The PH value of 20 nitric acid to solution is between 1 and 2, 3 to 4 drops of 0.2% dmophenol orange indicator, with 0.15M of nitrate solution titration to the solution from yellow to red, that is, the end point.
the volume ratio of the two is calculated by pressing: formula
(2)
: a - the standard solution per milliliter of nitrate is equivalent to the number of milliliters of the EDTA standard solution.
V - the number of milliliters of nitrate consumed at titring.
test results:
.1
: sample content is basically more than 90%, high purity.
1.2 titanium white powder crystal type detection
tu.1 titanium white powder
A figure.2 titanium white powder B
figure.3 titanium white powder C
figure.4 titanium white powder D
figure.5 titanium white powder E
figure .6 Titanium White Powder F
Figure.7 Titanium White Powder G
Figure.8 Titanium White Powder H
Test Results: table
.2
Eight types of titanium dioxide powder are almost all of the redstone type, of which F contains a small amount of sharp titanium type titanium white powder.2, sample detection
titanium dioxide is generally treated with a bread film, the purpose is to improve its durability and weather resistance, improve wetting dispersion, improve the surface gloss of the coating, increase the fluidity of the paint film. Therefore, in addition to the above-mentioned titanium dioxide purity testing, should also detect titanium white powder in the powder coating of other properties.
2.1,
in accordance with the test standard formula samples, plate after the following experiments.
2.2, Test items and results Table
.3
The L values of eight types of titanium dioxide are as follows: the L values of
Figure.9 TiO2 are compared to the
b values of eight titanium white powders are as follows:
Figure.10 TiO2 b values are compared to
temperature and gas resistance:
Figure.9 TiO 2 Temperature and gas resistance comparison figure
weather resistance:
Figure.11 TiO2 QUV-313 aging preservation rate map
as can be seen above: Table
.4
2.3 knot
from the above experimental results can be seen:
a. in whiteness, D, G, H better than other titanium dioxide.
b. In temperature-resistant yellowing performance, titanium dioxide B, G, H performance is better.
c. In terms of covering force, G, H is better than other titanium dioxide
d. If used in weather-resistant powder, choose G best.3.Conclusion
Titanium white powder purity testing, the above eight samples of TiO2 content is basically more than 90%, high purity, and eight samples of TiO2 redstone-type content is very high, of which F contains a very small amount of sharp titanium-type titanium white powder. Titanium white powder in the powder coating of other properties, whiteness, D, G, H is better than other titanium white powder, in temperature-resistant yellowing performance, titanium white powder B, G, H performance is better, in terms of cover force, G, H is better than other titanium white powder, if used for weather-resistant powder, the best choice of G. In the end, the combined performance of titanium white powder G is the best.
in summary, the detection of titanium dioxide should be from the titanium white powder TiO2 content, crystal type and in the powder coating testing of various performance aspects of comprehensive consideration, the selection of suitable titanium white powder to meet the performance of powder coating products.