Anti-clumping properties of Silica and Alumina C in powder coatings

Anti-clumping properties of Silica and Alumina C in powder coatings

Yu Jia, Yao Shengzhou (Wuhan Yincai Technology Co., LTD.)

Abstract: This study compares the effects of silica and alumina C on anti-agglomeration in powder coatings, storage performance of powders, and coating appearance. The addition of silica and alumina C requires external force to disperse them into the powder matrix, which significantly enhances powder storage efficiency and results in superior coating quality.

I. Introduction

With the improvement of national environmental protection requirements, many enterprises carry out transformation from paint to powder, and the powder coating industry develops rapidly. With a large increase in the amount of powder coating, the storage of powder coating becomes important, especially in hot summer weather, powder coating is easy to clump.

II. THE EXPERIMENTAL PART

Experimental method: Under the condition of 40℃,45℃, and constant temperature for 12 hours, 0.1%,0.2%,0.3%, and 0.5% of silica fume and alumina C were added to observe the effect of powder anti-agglomeration, and the spray plate was observed to observe the influence of adding 0.1%,0.2%,0.3%, and 0.5% of silica fume and alumina C on powder coating and appearance.

 Experimentation ：

2.1 Powder anti-clumping test (manual slow mixing)

Sample powder preparation: Take 1 kg of large production black powder and add 1 g, 2 g, 3 g, and 5 g of anti-agglomeration additives respectively. Hand-mix and shake until uniform, then pass through a 120-mesh sieve. After sieving, shake again, take 100 g, seal it, and place in an oven for testing.

• 40℃, clumping effect of different amounts of alumina C powder under 12 hours of oven temperature. 

Comparison diagram of alumina C added 0.1%,0.2%,0.3%,0.5%

                                                                             0.1%                           0.2%                           0.3%                      0.5%

The effect of different amounts of white carbon black powder agglomeration under 12 hours of oven temperature

                                                                             0.1%                          0.2%                        0.3%                       0.5%

• 45℃, effect of different additives on powder agglomeration under the condition of oven temperature for 12 hours.

                                                                                Alumina C, from left to right, are 0. 1%,0.2%,0.3%,0.5%

                                                                                Silica, from left to right, are 0. 1%,0.2%,0.3%,0.5%

Explanation: If the temperature is too high, reaching 45℃, it is difficult to achieve anti-agglomeration with 0.3% alumina C and silica.

2.2 Coffee grinding mixed with silica, alumina C, and investigate their effects on the powder (machine mixing and rapid mixing).

For sample powder preparation, take 200 grams of the aforementioned large production sample powder and add 0.2g,0.4g, and 0.6g of silica fume, as well as 0.2g,0.4g, and 0.6g of alumina C respectively. Pour into a coffee grinder, mix intermittently for 8 seconds, then pour out and shake well before use.

2.2.1 Take 50 grams of sample powder respectively, put it in a 40℃ oven, keep the temperature for 12 hours, and observe the effect

2.2.2 Take 50 grams of sample powder respectively, put it in a 45℃ oven, and observe the effect after 12 hours of constant temperature

1) Alumina C, 0.2g,0.4g,0.6g

2) White carbon black, 0.2g,0.4g,0.6g

Note: The anti-agglomeration effect of dispersing silica/alumina C into powder with coffee grinder is better than that of hand mixing.

2.3 Results analysis shows that:

A. From the analysis of experimental results, the effect of alumina C on powder agglomeration is obviously better than that of silica.

B. 40℃ When the condition addition is 0.3%, there is no great difference between alumina C and silica, but alumina C powder is significantly drier.

C. The amount of alumina C and silica increased significantly, and the anti-clumping effect was improved.

D. The effect of dispersing silica/alumina C into powder with coffee grinder is better than that of hand shaking mixing.

2.4 Test on the influence of alumina C and silica on powder coating and appearance

2.4.1 Spray plate observation of powdering and surface appearance of the sample

Mix slowly, take the prepared sample powder and use the same spraying technique twice, up and down. Add the amount of silica

0.1%,0.2%,0.3%,0.5%. The sample thickness is about 70 microns respectively. Alumina C, the sample thickness is about 70 microns respectively.

                                     Add 0.1%,0.2%,0.3%,0.5% of silica

                                 Oxidized aluminum C added 0.1%,0.2%,0.3%,0.5%

2.4.2 Mechanically mixed and fast mixed alumina C and silica fume, spray plate, investigate the influence on powder

2.4.3 Spray powdering test

                                                        Alumina C

                                                                           No added                 0.1%                  0.2%                   0.3%              0.5%

                                                                    Carbon-white 

                                                                     0.1%                             0.2%                         0.3%                         0.5%

2.4.4 Results analysis:

A. The influence of alumina C on powder is relatively small compared with silica.

B. With the increase of the amount, the addition of silica at 0.5% seriously affects the leveling and powdering.

When the amount of additive is increased above 0.3%, it has a bad effect on powder charging and powdering to varying degrees.

III. CONCLUSIONS

In summer when the weather is hot, it is recommended to use alumina C to improve the anti-clumping ability of powder. In order to achieve the best effect, alumina C should be used below 0.2%-0.3%, which can not only effectively improve the anti-clumping ability of powder, but also ensure that the appearance and spraying effect of powder are not affected.