Analysis of the advantages and recommended applications of aluminum silicate series products

As a multifunctional filler, SIPERNAT ^®  820 A has always been Evonik's star product in ink applications.

 In addition to the star product SIPERNAT ^® 820 A, the aluminum silicate series also includes other products such as SIPERNAT ^®  830, SIPERNAT ^®  833 and SIPERNAT ^®  835.

All aluminum silicate products have the characteristics of increasing white ink hiding rate, improving ink anti-adhesion, improving overprint ink transfer and matting.

^{Although other products are not as good as SIPERNAT ®} 820 A in terms of white ink hiding rate and whitening effect , they each have their own uniqueness, which also determines that they are different from SIPERNAT ^®  820 A and can be applied to different requirements.

SIPERNAT ^®  833 has better grindability than SIPERNAT ^®  820 A.

We prepared 100 grams of 8% aluminum silicate slurry according to the following formula, and the grinding resin was 30% Degalan 64/12 N acrylic resin liquid (the solvent was n-propyl ester).

The test recipe is as follows:

After adding glass beads, oscillate and grind, and compare the time taken for the slurry to be ground to a fineness of <20um.

Figure 1 Comparison of the time required for the dispersion fineness of aluminum silicate

As can be seen from the above figure, SIPERNAT  ^® 833 is the easiest to grind and disperse, followed by SIPERNAT ^®  820 A. Domestic competing products have the worst grinding and dispersibility.

It can be seen that SIPERNAT ^®  833 is particularly suitable for white ink applications that have high requirements for grinding and dispersibility.

SIPERNAT ^®  835 has excellent stirring dispersibility and is particularly recommended for certain applications that do not require grinding and dispersion but only require stirring and dispersion.

Take water-based printing paste as an example: the original formula contains 35% titanium dioxide, and 4% of the titanium dioxide in the test formula is replaced by aluminum silicate, and the dispersion condition is 2000RPM/20 minutes. After testing, the fineness is as follows:

Figure 2 Comparison of the fineness of aluminum silicate used in printing paste

According to the above experimental results, it can be seen that under stirring dispersion conditions, the dispersion effect of SIPERNAT ^®  835 is better.

SIPERNAT ^®  835 is also widely used in carton inks or varnishes due to its easy stirring and dispersion characteristics. It not only provides good anti-slip effects, but also avoids the problem of easy precipitation of traditional filler calcium carbonate.

Below is a comparison of water-based blue inks used for carton inks, containing 10% SIPERNAT ^® 835 and 10% calcium carbonate precipitation.

Figure 3 Comparison of SIPERNAT  ^® 835 and calcium carbonate precipitation

(Storage conditions: 50℃, one week)

Figure 4 - Comparison of dynamic friction coefficient of printed ink after adding SIPERNAT ^® 835 and calcium carbonate to carton ink 

It can be seen that SIPERNAT ^®  835 not only has a good anti-slip effect, but also does not settle. In specific applications, calcium carbonate and SIPERNAT  ^® 835 can also be used in combination.

SIPERNAT  ^® 830 is  the product that is closest in performance to SIPERNAT ^{® 820 A.}

Due to the recent surge in titanium dioxide prices, SIPERNAT ^®  820 A continues to be a hot seller, and customers have raised various questions.

Question 1

🎤 SIPERNAT ^®  820 A is not easy to grind and disperse in white ink.

^{👨‍🏫 Considering that titanium dioxide has a higher specific gravity than aluminum silicate, it is recommended to add SIPERNAT ®}  820A first and then titanium dioxide during stirring and dispersing , so that the dispersion effect is better.

Of course, it is also possible to replace SIPERNAT ^{® 820 A with SIPERNAT ®} 833  which has better dispersibility  .

Question 2

🎤 When SIPERNAT ^®  820 A is used to improve the transferability of overprinting ink, will it affect the gloss of the ink?

👨‍🏫 When SIPERNAT ^®  820 A is used to improve the transferability of overprinting ink, the added amount is only 0.3%-0.5%, so it basically does not affect the gloss of the ink.

Question 3

🎤 What is the appropriate amount of SIPERNAT ^®  820 A? Why is it not white sometimes?

👨‍🏫 SIPERNAT ^®  820 A is added in packaging inks at 5%-10% of the titanium dioxide content , and in printing pastes at 3%-5% of the total formula . Since SIPERNAT ^®  820 A needs to interact with titanium dioxide to improve the hiding rate, the more titanium dioxide in the formula, the more obvious the effect. Generally, a titanium dioxide content of more than 30% in the original formula is preferred .

Question 4

🎤 In composite packaging inks, customers often report that SIPERNAT ^®  820 A affects the surface roughness of the ink, which in turn affects the effect of solvent-free glue composite.

👨‍🏫 The amount of SIPERNAT ^®  820 A added can be reduced, and SIPERNAT ^®  820 A can be used to replace both the matting powder and titanium dioxide in the formula. This can maintain the film roughness of the ink, thereby improving the white ink coverage and reducing costs.

Take the following formula as an example:

Compare the gloss of ink as follows (gloss can reflect the roughness of ink)

Figure 5. Comparison of the glossiness of composite white ink

As can be seen from the above figure, the roughness caused by two parts of aluminum silicate is close to the roughness caused by one part of matting powder.

Figure 6 Comparison of composite ink coverage

From the above experimental results and the comparison between A1 and B1, A2 and B2, A3 and B3, it can be seen that 1 part of aluminum silicate can replace 0.5 parts of matting agent and 1 part of titanium dioxide at the same time, which can maintain the original roughness of the ink , improve the ink coverage and reduce the ink cost. Of course, SIPERNAT ^®  833, which has less impact on the roughness of the ink, can also be selected , but its coverage is slightly worse than SIPERNAT ^®  820 A.