AEROSIL® and AEROXIDE® fumed metal oxides for powder coatings Technical Information 1340

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Introduction

Technical Fundamentals of AEROSIL® and AEROXIDE® for Powder Coatings

New Investigations on AEROSIL® and AEROXIDE® in Powder Coatings

Test Methods

Flowability

Angle of Repose

Bed Expansion

Transfer Efficiency

Faraday Cage Effect

Gloss

Gel Time

AEROSIL® and AEROXIDE® Products in Polyester based

Powder Coatings (Corona Application)

Flowability

Angle of Repose Test

Bed Expansion Test

Transfer Efficiency

Faraday Cage Effect

Gloss

Gel Time

AEROXIDE® Products in Polyester based Powder Coatings (Tribo Application)

Transfer Efficiency

Faraday Cage Effect

Physico-Chemical Data and Registration of AEROSIL® and AEROXIDE®

Conclusion

Table of contents

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1 Introduction

The global market for powder coatings is expected to grow at rates higher than liquid coatings due to the ongoing shift from conventional solvent-borne to more environmental-ly-friendly coating systems. The overall growth rate is estimat-ed to be in the range of 5 – 6 % in the years ahead. While North America and Western Europe should see a more moderate growth, an above average increase in powder coatings produc-tion and consumption is expected for South-East-Asia, China, India and Eastern Europe.

In order to remain competitive, it will be essential for powder coating manufacturers to develop innovative solutions and systems offering superior performance. Differentiation from the competition can be achieved by demonstrating proper-ties such as free flow, transfer efficiency and edge covering. AEROSIL® fumed silica and AEROXIDE® fumed oxides are well known for enhancing and optimizing manufacturing, quality, appearance and overall performance of powder coatings.

A recent study performed between the Evonik Industries AG and the University of Western Ontario, Canada, shows the performance of newly developed fumed oxides in comparison to the established product range of AEROSIL® fumed silica and AEROXIDE® fumed oxides. All tests were conducted in a polyester based coarse powder coating in comparison to a fine powder coating system and we will present the findings beginning in Chapter 3.

2 Technical Fundamentals of AEROSIL® and AEROXIDE® for Powder Coatings

AEROSIL® fumed silica is an amorphous silicon dioxide with an extremely small primary particle size. Hydrolysis of chlorosi-lanes in an oxygen-hydrogen flame produces this fluffy white powder of high purity. Primary particles in the range of 7 to 40 nm result, in a wide range of specific surface areas, from 380 down to 50 m2/g. By using the AEROSIL® process, other special oxides (brand name AEROXIDE®) such as fumed alu-minium oxide, titanium dioxide or zirconium oxide have been developed.

AEROSIL® and AEROXIDE® • Improve free flow characteristics• Enhance storage stability• Reduce moisture pick-up• Improve edge covering• AEROXIDE® Alu C increases the electropositive chargeability of tribo powders

To considerably improve free flow properties, 0.1 to 0.3 % by weight (on total) of AEROSIL® fumed oxides should be added to the powder coating. When incorporating AEROSIL® fumed oxides by suitable feeders before the final milling step, high homogeneous distribution results throughout the powder coating can be achieved. Another common incorporation method is the addition of AEROSIL® fumed oxides at the end of the milling process by dry blending (after classification). Using this approach, there is a possibility that larger agglomerates may remain. Finally, the manufacturer has the option to adjust the incorporation to suit their specific processes and perfor-mance requirements.

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AEROSIL® 200 and AEROSIL® 380 are hydrophilic fumed silicas which can be added into the hopper at 0.1 - 0.3 % by weight (based on total) to improve blending of powders giving a more homogeneous dry mix ready to be fed into the extrud-er. Processing rheology is improved which allows for faster throughput and less hang-up in the extruder. AEROSIL® R 972 is a hydrophobic fumed silica which can be added into the hopper at 0.1 – 0.3 % by weight (based on total) to improve blending and give a more homogeneous dry mix. Excessive static charge build-up of powdered raw materials in the hopper causes fine particle size components to cling to the walls preventing a homogeneous blend and the feeding of material into the extruder. AEROSIL® R 972 can also be added at 0.1 – 0.3 % by weight (based on total) before pulverization and ground with the powder to reduce static charge, improve flow of the final product and flow during deposition.

Powder Coatings Systems Products Concentration in wt % Effect

Thermosettings Powders• Low molecular weight epoxy • TGIC-polyester• Epoxy polyester hybrids • Polyurethanes • Acrylics

AEROSIL® 200, AEROSIL® 380, AEROSIL® R 972, AEROSIL® R 812, AEROSIL® R 8200 AEROXIDE® Alu C, AEROXIDE® Alu C 805

0.1 – 0.3 0.1 – 0.3 0.1 – 0.3 0.1 – 0.3 0.1 – 0.3 0.1 – 0.3

- Free flow additive - Anti-caking (prevention of moisture pick-up)

Thermoplastic Powders• Vinyl• Nylon• Polyolefin• Fluorcarbon types

AEROSIL® R 972, AEROSIL® R 812, AEROSIL® R 8200 AEROXIDE® Alu C, AEROXIDE® Alu C 805

0.1 – 0.3 0.1 – 0.3 0.1 – 0.3 0.1 – 0.3

- Free flow additive - Anti-caking (prevention of moisture pick-up)

Tribopowders• Epoxy polyester hybrids• Epoxy acrylate hybrids

AEROXIDE® Alu C, AEROXIDE® Alu 130

0.1 – 0.3 - Free flow additive - Increase in electropositive charge (tribo)

Table 1 General overview of the use of AEROSIL® and AEROXIDE® fumed

AEROSIL® R 972 imparts a slight hydrophobic character to the powder preventing moisture pick-up during storage which can cause caking. AEROSIL® R 972 can be dry blended after pulverization if it is not possible to add prior due to being separated out in the classifiers. The loading levels of AEROSIL® R 972 are within the same range whether added before or after pulverization, however, before pulverization gives the optimum results.

The electrostatic charge of the powder coating will not be adversely affected, regardless of whether the powder has a positive or negative charge. The use of hydrophobic AEROSIL® grades will ensure a long-lasting and consistent chargeability due to its moisture protection. The generally very low added amounts of < 0.5 % do not negatively influence the levelling of the powder coatings during curing. AEROXIDE® Alu C, which is produced using the same pro-cess as the AEROSIL® fumed silica, has a special, dual perfor-mance enhancement status. Unlike most AEROSIL® products,

which have strong tendencies toward negative charges, AEROXIDE® Alu C has a strong tendency to a positive charge. For this reason, this product is often used in powder coatings that are triboelectrically applied, both to increase the electro-positive charge of the powder coating during application to enhance the deposition or transfer efficiency and also to re-duce static charge build-up in the final powder coating which can negatively influence bulk flow properties.

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AEROSIL® R 812 and AEROSIL® R 8200 are HMDS treated fumed silicas which are characterized by their strong hydrophobicity. The very hydrophobic nature of these grades provides an excellent moisture protection and an elevated chargeability. AEROXIDE® Alu C is a positively charged fumed aluminium oxide which can be added before pulverization or dry blended as an after treatment for all types of powder coatings. Due to the positive charge, it is extremely suited for tribo applications and in some cases AEROXIDE® Alu C makes non-tribo chargeable powders tribo-chargeable. AEROXIDE® Alu C and AEROXIDE® Alu 130 are included to reduce static charge which reduces flow and assists the deposition of the powder during application. Recommended loading levels are between 0.1 – 0.3 % by weight (based on total). The benefits of AEROXIDE® Alu C and AEROXIDE® Alu 130 are due in part to the fine particle size and distribution from our manufacturing process and the surface charge of the particle itself.

AEROXIDE® Alu C 805 is an Octylsilane treated fumed aluminium oxide. By adding 0.1 – 0.3 % by weight (on total) it improves the flowability of all types of powder coatings. Due to its hydrophobic character AEROXIDE® Alu C 805 reduces moisture pick-up and enhances storage stability. AEROSIL® Fumed Silica improves free flow characteristics

right: Powder coating without AEROSIL® fumed silicaleft: Powder coating with AEROSIL® R 972

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3 New Investigations on AEROSIL® and AEROXIDE® in Powder Coatings

Product Character BET Surface[m²/g]

Tapped Density [g/L]

Surface Chargez

AEROSIL® 200 Hydrophilic Silica 200 ± 25 50 Negative

AEROSIL® R 812 Hydrophobic Silica 260 ± 30 60 Negative

AEROSIL® R 972 Hydrophobic Silica 110 ± 20 50 Negative

AEROXIDE® Alu C Hydrophilic Aluminium Oxide 100 ± 15 50 Positive

AEROXIDE® Alu C 805 Hydrophobic Aluminium Oxide 100 ± 15 50 Slightly Positive

AEROXIDE® Alu 130 Hydrophilic wwAluminium Oxide 130 ± 20 50 Positive

Table 2 Evaluated fumed silica and aluminium oxides

This Technical Information brochure provides information regarding a recent study of performance properties including flow behavior, which can be influenced by fumed silica or aluminium oxides in a customary powder coating. Increasing environmental concerns, combined with the need to contain costs and achieve improved appearance properties have accelerated the trend toward development of thinner powder coating films. This is being achieved through the use of smaller particle size powder coatings and as a consequence opens the door to using different additives to optimize performance. To meet the existing and future requirements of powder coat-ings, two different particle sizes were included in the study and a variety of performance properties were tested. Specific at-tention was paid to ultra fine powders, as good flow and spray characteristics are known to be a challenge to achieve.

While use of hydrophilic and hydrophobic fumed silica (AEROSIL®), and hydrophilic aluminium oxide (AEROXIDE®) are well known in the powder coatings industry, Evonik has developed new fumed oxides, which enhance the properties of powders. In cooperation with the University of Western Ontario, Canada, these new particles were tested in compari-son to the established product portfolio offered by Evonik for many years. This Technical Information gives an overview about the performance of fumed oxides in a polyester based powder coating including both, coarse and fine powders. All products included in this study are listed in Table 2 with their respective physical properties.

The main objective of the study was to evaluate the effective-ness of different fumed silicas and aluminium oxides on the performance of powder coatings. All tests have been made in a black polyester based formulation. To get a comprehensive overview about the performance in powder coatings of different fineness, two particle sizes were chosen (fine powder: d50 = 21.5 µm / coarse powder: d50 = 31.0 µm). The additive concentration was set 0.5 % by weight (based on total) for the fine and 0.3 % by weight (based on total) for the coarse powder coating. For both fine and coarse particles the additives were incorporated into the powder coating with AMC milling equipment using proprietary technology of the Uni-versity of Western Ontario, Canada. As a general rule, slightly higher loading levels of additive are needed to adequately cover smaller particle size powders. This is the background of the difference in loading levels, based on powder particle size.

The following tests have been performed with the polyester powder coatings:

• Angle of Repose (Flowability)• Bed Expansion (Flowability)• Powder Transfer Efficiency• Faraday Cage Effect• Gloss• Gel Time

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4 Test Methods

4.2 Transfer EfficiencyTransfer Efficiency tests were carried out with a GEMA manual spray gzzun and an aluminium target panel of 30 cm in diam-eter and 20 cm away from the gun. Each powder sample was tested three times with an initial powder mass of 3 grams each and the average transfer efficiency (E) was calculated from these three results (E1, E2 and E3):

4.1 Flo wability 4.1.1 Angle of Repose Angle of repose (AOR) is a commonly used parameter in determining the flowability of a powder. It is defined as the angle between the surface of the pile (formed by raining down the powder to a flat surface) and the flat surface. A lower angle of repose indicates a better flowability. 4.1.2 Bed Expansion Bed expansion ratio (BER) is another commonly used param-eter in determining the flowability of a powder. BER is defined as the ratio of fluidized bed height H over the initial fixed bed height H0 , which changes with the air velocity passing through the bed. A higher expansion ratio suggests improved powder performance, fluidization ability and flowability.

where m1, m2 and m3 were the powder mass transferred to the target panel.

4.3 Faraday Cage EffectFaraday Cage Effect tests were conducted with a specially designed aluminium panel of 7“ x 6“ with a 1“ deep x 1“ wide trough located in the centre, as shown in the the picture below.

Three strips of aluminium sheets (1“ x 6“) were attached to their corresponding positions (2 on the outside of the trough and 1 on the back wall inside the trough by small clips before spraying.

Transfer Efficiency E = = 3 3

3.0 3.0 3.0E1+ E2 + E3

m1 + m2 +

m3

Aluminium panel and 3 strips of aluminum sheets designed for the Faraday Cage Effect test

Aluminium panels and fixed strips after spraying

Aluminium sheets

Acrylic column used for the bed expansion tests

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R =minternal

mouter

mouter = 2

,+mouter (top) mouter (bottom)

Then the whole panel was hung in the spray booth with ground-ing connection. Each of the 3 strips was weighed before and after each spray to get the mass of powder deposited. By comparing the powder mass on the back wall inside the trough (minternal) with the average powder mass on the 2 strips outside of the trough (mouter) with

the Faraday Cage Effect can be determined by the ratio of these two mass numbers:

with R = 1 denoting no Faraday Cage Effect and R = 0 representing a maximum Faraday Cage Effect and no powder transferred to the internal surface.

4.4 GlossThe evaluation of the gloss values for the different samples of coarse and fine polyester powder was performed with the Novo-Gloss Gloss meter manufactured by Rohpoint Instru-mentation Ltd. According to the manufacturer, the assigned value has an uncertainty value of 0.5 units at 95 % confidence level. The selected angles of the incident light to carry on the test are 20 ̊ and 60 ̊ , these values are widely used in industry as a standard for gloss measurements. Each individual panel was measured six times at different points to calculate the average gloss value. 4.5 Gel TimeThe ASTM standard test method (D 4217-02) for gel time of a thermosetting powder coating was used for this experiment. This test method determines the amount of time required for a thermosetting coating powder to gel on a metal surface at a specified temperature. An equal mass of each sample was placed on a heated surface at 200 °C with a variance of +/- 2 °C. The time between initial heating and the onset of hardening, is defined as the gel time.

5 AEROSIL® and AEROXIDE® Products in Polyester based Powder Coatings (Corona application)

All samples for the tests of fumed silica and fumed aluminium oxides were prepared as described in chapter 3. The proce-dure for fluidization tests, transfer efficiency, Faraday Cage Effect, gloss and gel time were done according to chapter 4. 5.1 Flowability 5.1.1 Angle of Repose TestIn coarse as well as in fine polyester powder coatings, AEROXIDE® Alu C 805 showed the highest positive impact on the flow characteristics among the tested fumed aluminium oxides. The second best performing product was AEROXIDE® Alu 130 for both particle sizes (Figure 1 and 2).

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Figure 1 Angle of Repose of aluminium oxides in a coarse powder coating

Figure 2 Angle of Repose of aluminium oxides in a fine powder coating

* A low angle of repose indicates improved flow behaviour

* A low angle of repose indicates improved flow behaviour

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Figure 6 Bed Expansion test with silica and aluminium oxides inthe coarse powder coating

Regarding the use of fumed silica in the polyester based test material, AEROSIL® R 812 and AEROSIL® 200 enhanced the flow properties to a higher extent compared to all other tested silica products (Figure 3 and 4). This statement can be applied for the fine and coarse polyester powder coating.

* A low angle of repose indicates improved flow behaviour

* A low angle of repose indicates improved flow behaviour

5.1.2 Bed Expansion Test In comparison to the angle of repose test, the bed expansion test is the more direct characterization method when evaluating the fluidization properties of a powder coating. In Figure 5 and 6, the results for all silica and aluminium oxides are given. The graphics show the air velocity U [cm/s], which is needed to obtain 20 % bed expansion. The air velocity of the control without silica or aluminium oxide was always > 1 cm/s. All tested silicas and aluminium oxides clearly improve the flowability of the polyester based powder coating in the bed expansion test. For the fine polyester powder, aluminium oxides are observed to be more effective compared to silica products with AEROXIDE® Alu C 805 and AEROXIDE® Alu C performing best. For the silica materials, the best result was obtained with the hydrophobic AEROSIL® R 812. In the coarse powder coating, fumed silicas were observed to be slightly better as a fluidization additive. However results obtained with AEROXIDE® Alu C 805 and AEROXIDE® Alu 130 are very close in performance.

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R 812 200

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R 972

Worse

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Figure 3 Angle of Repose of silicas in a coarse powder coating

Figure 4 Angle of Repose of silicas in a fine powder coatingFigure 5 Bed Expansion test with silica and aluminium oxides in the

fine powder coating

Overall it can be stated that all tested additives improve the flow behaviour in the angle of repose test. Superior flow properties are provided by AEROSIL® R 812, AEROSIL® 200 and AEROXIDE® Alu C 805 in the coarse and fine polyester powder coating system.

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As a summary of the overall result: for coarse and fine polyester powder coatings AEROXIDE® Alu C 805 and AEROSIL® R 812 are the products which provide the highest efficiency concerning positive impact on fluidization. Due to their hydrophobic nature, both materials, in addition to their excellent flow behaviour, prevent moisture pick up of the pow-der coating during storage and processing. It must be noted here that selection of the best additive to enhance fluidiza-tion performance is always formulation dependent. It is very possible that what works best in one system may not give the optimum results in all formulations.

5.2 Transfer EfficiencyTo evaluate the transfer efficiency with the corona process, a GEMA spray gun with a target panel of 30 cm diameter and 20 cm distance between panel and gun was used. 3 g of pow-der coating were sprayed to cover the disks. The higher the coverage of the disks after spraying, the more powder coating was transferred. The drying time was ten minutes at 200 °C.

It was evident that the results for the transfer efficiency are very much dependent on the particle size of the powder coating. Additives which enhanced the transfer efficiency for fine powders tended to reduce the transfer efficiency of the coarse powder coating. In fine powders AEROSIL® 200 and AEROSIL® R 812 performed best (Table 3) while in coarse powders AEROXIDE® Alu 130 and AEROXIDE® Alu C gave favourable results (Table 4).

5.3 Faraday Cage Effect For the tests of the Faraday Cage Effect the powder coatings were sprayed with the GEMA spray gun onto the panels. The final evaluation of the covering effect was evaluated as out-lined in chapter 4.3. A maximum Faraday Cage Effect provides bad coverage and that corresponds to a low “R” value. R = 1 represents no Faraday Cage Effect and a uniform coverage over the entire substrate.

In fine powder materials, silica additives help to overcome the Faraday Cage Effect and achieve a more uniform coverage of the substrate results show AEROSIL® R 812 clearly improves this performance attribute.

0.60

0.63

0.66

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R

AEROSIL®

R 812

AEROSIL® AEROSIL®

200 R 972

Control

Worse

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Product AEROSIL® 200

AEROSIL® R 812

AEROXIDE® Alu C

Control

Transfer Efficiency [%] 77 72 71 66

Product AEROXIDE® Alu 130

AEROXIDE® Alu C

AEROXIDE® Alu C 805

Control

Transfer Efficiency [%] 80 78 75 65

Figure 7 Influence of AEROSIL® fumed silica on the Faraday Cage Effect in a fine powder coating. R = 1 denotes no Faraday Cage Effect (good substrate coverage) and R = 0 representing a maximum Faraday Cage Effect (bad substrate coverage)

Table 3 Results of Transfer Efficiency in the fine powder coating

Table 4 Results of Transfer Efficiency in the coarse powder coating

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Figure 9 Transfer Efficiency of aluminium oxides in the fine powder coating

In coarse powder materials, only AEROXIDE® Alu C 805 improved the coverage slightly. All other tested silica and aluminium oxides did not provide noticeable benefits for the Faraday Cage Effect. 5.4 GlossGloss reductions were observed from the addition of each of the silica additives, for both incident angles (20° and 60°) and for both coarse and fine powders. AEROSIL® R 972 pro-vided less influence on the gloss compared to all other tested fumed silicas. The test results indicate that generally silica additives have a greater impact to gloss than the aluminium oxide additi-ves. Excellent performance was demonstrated by AEROXIDE® Alu C 805, which did not influence the gloss of the powder coatings panels.

5.5 Gel TimeFor the gel times of coarse materials nearly no influence was observed with AEROXIDE® Alu 130 and AEROXIDE® Alu C 805 while AEROSIL® R 812 and AEROSIL® 200 tended to prolong the gel time. The same tendency was witnessed for the fine polyester powder coating, but due to the reduced particle sizes the onset of hardening was slightly faster compared to the coarse materials.

6 AEROXIDE® Products in Polyester based Powder Coatings (Tribo Application)

In addition to the improvement of the flow properties, fumed aluminium oxide is often used to improve the chargeability of powders for the tribo application. For this reason, the influence of different aluminium oxide additives on the transfer efficiency and the Faraday Cage Effect was evaluated separately. 6.1 Transfer Efficiency The transfer efficiency was again performed as outlined in chapter 4.2. For the tests of different aluminium oxides a tribo application with a Nordson Tribomatic 631302C manual spray gun was used. All tested aluminium oxides improved the transfer efficiency of the polyester material. While for the corona application the re-sults are very much dependent on the particle size of the pow-der coating (see chapter 5.2), AEROXIDE® Alu C 805 showed a superior improvement of the transfer efficiency in the tribo application, independent of the powder coating particle size.

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Figure 8 Transfer Efficiency of aluminium oxides in the coarse polyester powder coating

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6.2 Faraday Cage EffectThe Faraday Cage Effect was tested according to the method described in chapter 4.3. For the spraying a Nordson Tribomatic 631302C manual spray gun was used. A maximum Faraday Cage Effect provides a bad coverage and that means a low “R” value. R = 1 represents no Faraday Cage Effect and a consistent coverage all over the substrate.

In the coarse powder coating, an improvement in covering the three-dimensional aluminium sheets was achieved with all tested aluminium oxides. AEROXIDE® Alu C 805 and AEROXIDE® Alu 130, in particular, showed a nice improve-ment of the powder penetration (Figure 10). In the fine powder coating only AEROXIDE® Alu 130 helped to overcome the Faraday Effect and to enhance the powder penetra-tion in deeply recessed areas of the aluminium sheet.

Figure 10 Faraday Cage Effect of the coarse powder coating with tribo application

R

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Alu C 805 Alu C Alu 130

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7 Physico-Chemical Data and Registration of AEROSIL® and AEROXIDE®

AEROSIL® AEROXIDE®Testmethod Unit 200 380 R 972 R 812 R 8200 Alu 130 Alu C Alu C 805

Specific surface area (BET) m2/g 200 ± 25 380 ± 30 110 ± 20 260 ± 30 160 ± 25 130 ± 20 110 ± 15 90 ± 15

Tapped density (approx. value ex plant) acc. to DIN EN ISO 787/XI, Aug. 1983 g/l 50 50 50 60 140 50 50 50

Moisture (ex plant) 2 hours at 105 °C wt. % ≤ 1.5 ≤ 2.0 ≤ 0.5 ≤ 0.5 ≤ 0.5 ≤ 5.0 ≤ 5.0 ≤ 2.0

pH-value in 4 % dispersion 3.7 – 4.7 3.7 – 4.7 3.6 – 4.4* 5.5 – 7.5 ≥ 5.0 4.4 – 5.4 4.5 – 5.5 3.0 – 4.5

Carbon content wt. % – – 0.6 – 1.2 2.0 – 3.0 2.0 – 4.0 – – 3.5 – 4.5

SiO2-content based on ignited material wt. % ≥ 99.8 ≥ 99.8 ≥ 99.8 ≥ 99.8 ≥ 99.8 ≤ 0.10 ≤ 0.10 ≤ 0.10

Al2O3-content based on ignited material wt. % ≤ 0.05 ≤ 0.05 ≤ 0.05 ≤ 0.05 ≤ 0.05 ≥ 99.8 ≥ 99.8 ≥ 95.0

The data have no binding force.

The data have no binding force.

* Production in Rheinfelden

Table 5 Physico-chemical data and registration of AEROSIL® and AEROXIDE®

EINECS(Europe)

TSCA (USA) AICS (Australia) DSL (Canada) PICCS (Philippines)

MITI (Japan)

KECI (Korea)

IECS (China)

NZloC (New Zealand)

AEROSIL® 200 registered registered registered registered registered registered

AEROSIL® 380 registered registered registered registered registered registered

AEROSIL® R 972 registered registered registered registered registered registered

AEROSIL® R 812 registered registered registered registered registered registered

AEROSIL® R 8200 registered registered registered registered registered registered

AEROXIDE® Alu C registered registered registered registered registered registered

AEROXIDE® Alu C 805 registered registered registered registered registered

AEROXIDE® Alu 130 registered registered registered registered registered registered

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8 Conclusion

The study of fumed silicas and fumed aluminium oxides in the polyester powder coatings has once again confirmed the positive effects that nano structured particles impart to powder coatings. While AEROXIDE® Alu C, AEROSIL® 200, AEROSIL® R 812 are well known for their excellent suitability in enhancing the desired properties of powder coatings, this study has shown that recent developments such as AEROXIDE® Alu C 805 and AEROXIDE® Alu 130 offer additional benefits in the tested systems.

Consistent improvement was demonstrated in powder coatings treated with hydrophobic aluminium oxide AEROXIDE® Alu C 805, and it proved to be a very efficient additive to improve the flow behavior in fine and coarse powder coatings as well. Focusing on the tribo application, the Transfer Efficiency of AEROXIDE® Alu C 805 was superior in both fine and coarse powders while the Faraday Cage Effect was overcome especially in coarse materials.

For the specific system used for this study it can be concluded that AEROXIDE® Alu C 805 and AEROSIL® R 812 showed the best overall results and can therefore be considered the most suitable additives for both, coarse and fine particle size powders.

Our most recent product developments will enable you to further improve the performance of your individual powder coating systems in order to compete in the growing powder coating market with highly innovative product solutions. We will be happy to assist you with our technical expertise to select the most suitable prod-uct for your specific system.

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This information and any recommendations, technical or otherwise, are presented in good faith and believed to be correct as of the date prepared. Recipients of this information and recommendations must make their own determination as to its suit-ability for their purposes. In no event shall Evonik assume liability for damages or losses of any kind or nature that result from the use of or reliance upon this information and recommendations. EVONIK EXPRESSLY DISCLAIMS ANY REPRESENTATIONS AND WARRANTIES OF ANY KIND, WHETHER EXPRESS OR IMPLIED, AS TO THE ACCURACY, COMPLETENESS, NON-INFRINGEMENT, MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE (EVEN IF EVONIK IS AWARE OF SUCH PURPOSE) WITH RESPECT TO ANY INFORMATION AND RECOMMENDATIONS PROVIDED. Reference to any trade names used by other companies is neither a recommendation nor an endorsement of the corresponding product, and does not imply that similar products could not be used. Evonik reserves the right to make any changes to the information and/or recommendations at any time, without prior or subsequent notice.

AEROSIL® and AEROXIDE® are registered trademarks of Evonik Industries or its subsidiaries.

Europe / Middle-East /Africa / Latin AmericaEvonik Resource Efficiency GmbHBusiness Line SilicaRodenbacher Chaussee 4 63457 HanauGermany phone +49 6181 59-12532 fax +49 6181 59-712532 ask-si@evonik.comwww.evonik.com

North America

Evonik CorporationBusiness Line Silica 299 Jefferson RoadParsippany, NJ 07054-0677USA phone +1 800 233-8052 fax +1 973 929-8502ask-si-nafta@evonik.com

Asia Pacific

Evonik (SEA) Pte. Ltd.Business Line Silica3 International Business Park#07-18, Nordic European CentreSingapore 609927 phone +65 6 809-6877 fax +65 6 809-6677ask-si-asia@evonik.com

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