Nanomill ZETA® RSInnovation in Wet Grinding Technology

our technologyYOUR SUCCESS

Grinding & Dispersing

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Nanomill ZETA® RS

The Future Starts Today

The demand for materials with particle sizes in the nanometer range is increasing. Reasons are functionoriented advantages that these materials have in the fi nal product. In the colloidal particle size region it is important to distinguish between real comminution, dispersing and disag-gregating. For coarse, primary parti-cles, high pressure and impact stresses are required for real comminution. For agglomerated nano-scale particles that require only dispersing, the direct stresses of real grinding damage the

crystal structure of the nanoparticle. Reason for this is the change in the mechanical characteristic of the product particles with decreasing particle size, from brittle-elastic to plastic behavior. Changeovers from crystalline to amor-phous material structure or mechan-ical-chemical activated reactions can negatively infl uence the product characteristics.Specially designed equipment is neces-sary for dispersing nano-structured systems or for production of nanoscale particles.

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Mild Dispersing

Nano-structured TiO2 particles for use in photo catalytic coatings are dispersed using varied agitator speeds (4 and 13 m/s). The desired degree of dispersion was achieved with an agitator speed of13 m/s however the result was the behavior of coatings with this material was inactive. Examinations with X-ray diffraction structure analysis showed that compared with gentle dispersing the crystalline mesh effect of the TiO2 has been destroyed due to the highly energetic stresses.

gentle dispersing

Med

ian

part

icle

siz

e x

50,3 /

μm

1

0.1

0.06

Specific energy input Em / kWh/kg10 200 30 40 50 60 70

Damages in structure, plastic deformation of the primary particles

Med

ian

part

icle

siz

e x

50,3 /

μm

1

0.1

0.06

Dispersion time tD / min100 20 30

GM: ZrO2 (Y2O3)GM = 0.9

dGM = 0.1 mmcm = 0.05

vt = 4 m/s

vt = 13 m/s

Diff

ract

ion

inte

nsity

/ cp

s

400

200

0

Diffraction angle 2 / °30 4020 50 60 70

X-ray structure analysis XRD

TiO2 - Dispersion0 sample13 m/s14 m/s

Nanomill ZETA® RS

Agglomerates of nano-scale primary particles should mainly be stressed by shearing under “gentle” conditions. For this the use of smallest grinding media at very low agitator speeds in agitator bead mills is necessary.

For this complex task, NETZSCH-Fein-mahltechnik GmbH was developing the new mill generation ZETA® RS.

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Handling

When developing the ZETA® RS machine series ergonomics was an important design criteria. Filling and emptying of the machine, service work and cleaning of the machine were parameters.

Swiveling grinding unit via hand wheel or electronic drive as an option (standard from machine size of 10 l)

Moveable grinding tank

Integrated, removable grinding media collection tray

Filling position Working position Emptying and cleaning position

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Grinding System

The agitator bead mills of the ZETA® RSseries were developed for use of grindingmedia in the range of 50 µm - 300 µm. Adaptation of geometric proportions of the NETZSCH ZETA® system circulationmill and the use of a new, innovativeseparation system were the design parameters.

Peg-grinding system with equivalent length/diameter proportion and high power density

Mode of Operation

Agitator bead mills of the type ZETA® RS can process in passage or circu-lation operation. Products in a wide range from gentle dispersing conditions(4 m/s) to very high energy densities(20 m/s) can be handled.

Nanomill ZETA® RS

Highly effi cient centrifugal separation system consisting of a hollow, slot-ted peg agitator shaft with centrically arranged rotating large-area separa-tion unit

Product inlet on bearing side

Product discharge through the drive- shaft occurs after grinding media separation

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ZETA® RS 2 ZETA® RS 4 ZETA® RS 10 ZETA® RS 25

Drive Power [kW] 7.5 15 25 45

Speed [min-1] 400 - 3,300 350 - 2,500 300 - 2,000 250 - 1,500

Grinding chamber volume [l] 2 4 10 25

Grinding media diameter [µm] 50 - 300 50 - 300 50 - 300 50 - 300

Separation Systems

High throughput rates in circulation operation and the use of grinding media in a range of 50 - 300 µm, are neces-sary for dispersing and real comminu-tion down to the nanometer range. These process requirements require a highly effi cient grinding media reten-tion system. Further development of the NETZSCH centrifugal separation system resulted in the rotating screen system or a newly developed, patent pending ODC (Open Dynamic Classi-fying) version.

Rotating screen system ODC-system

Advantages of the ODC system:

Processing of suspensions with coarse agglomerates

No loss of grinding media when starting and stopping the machine

No grinding media discharge also at high throughput rates

Discharge of contaminations and coarse product particles

Technical Data

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Grinding Chamber Materials

The machines of the ZETA® RS series are available in different wear resistant and corrosion resistant materials.

All grinding chamber parts of stain- less steel

Zirconium or SiC/Si 3N4 design for metal-free fi ne grinding of solvent-based products

Polyurethane or on request polyethyl- ene design for metal-free fi ne grind-ing of water-basedproducts

Nanomill ZETA® RS

Polyurethane design ZrO2 design

We offer the optimal solution for your demand.

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Advantages at a Glance

Compact design for minimal space requirement

Easy handling by swiveling grinding unit and sliding grinding chamber

Grinding media collection tray provides retention of expensive small beads and easy cleaning

Reliable use of smallest grinding media in a range of 50 - 300 µm

No screen blocking due to the ODC separation system (Open Dynamic Classifying-System)

Variety of materials available for grinding systems (can be interchanged)

Changeover from 4 l to the smaller 2 l design

Changeover

A special conversion kit was developed for the production of small product quantities. It enables a changeover from ZETA® RS 4 with 4 l grinding chamber volume to the grinding chamber design of the smaller ZETA® RS 2 with 2 l grinding chamber volume. Two adapter rings that are easily assembled (displayed in orange) provide a reduced grinding chamber diameter and smaller agitator shaft.

ZETA® RS 2ZETA® RS 4

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Applications

The machines of the ZETA® RS series are used for gentle dispersing as well as real comminution of various products such as pigments, inkjet, MLCC, functional coatings, nano ceramics, cosmetics and personal care, and many more. The following table shows a survey of dispersing results of different applica-tions that had been tested under gentle conditions.

Product ApplicationGrinding media material

Grinding media diameter

Peripheral speedAchieved particle size x50

Pigment LCD ZrO2(Y2O3) 0.1 mm 6 m/s 40 - 60

Pigment Inkjet ZrO2(Y2O3) 0.1 mm 6 m/s 13

TiO2 Photo catalyst ZrO2(Y2O3) 0.1 mm 6 m/s 44

ITO Electronic ZrO2(Y2O3) 0.1 mm 6 m/s 44

ZrO2 Electronic ZrO2(Y2O3) 0.05 mm 4 m/s 37

Diamond Polishing agent ZrO2(Y2O3) 0.1 mm 10 m/s 19

BaTiO3 MLCC Glass 0.1 mm 3 m/s 200

SiO2 Paper Glass 0.1 mm 8 m/s 40

Nanomill ZETA® RS

BaTiO3 before BaTiO3 after

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ETA® RS

Availability

A state-of-the-art application laboratory is available for tests at our headquarters in Selb, Germany. With the ZETA® RS 4 test station we can disperse, disaggre-gate or comminute nanoscale products.

Analytics

Extensive analytical instruments for determination of the grinding and dispersing particle size results and product viscosity are also provided in our laboratory.

Ultra sonic spectrometer DT 1200 with integrated measurement of the Zeta potential for suspensions in a concentration range from 1 to50 Vol. %; measuring area 0.005 to 100 µm

Horiba LB-550, dynamic light scatter- ing, integrated measurement of vis-cosity, measuring area 1 - 6,000 nm

Horiba LA-950, static light scattering combined with laser defl ection, mea-suring area 20 nm - 2 mm

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NETZSCH-Feinmahltechnik GmbHSedanstraße 7095100 SelbGermanyTel.: +49 9287 797-0 Fax: +49 9287 797 149info.nft@netzsch.com

The World’s Leading Grinding Technology

The Companies of the Grinding & Dispersing Business Unit

NETZSCH-Feinmahltechnik GmbH, Selb, Germany

NETZSCH-CONDUX Mahltechnik GmbH, Hanau, Germany

NETZSCH Premier Technologies, LLC., Exton PA, USA

NETZSCH Indústria e Comércio de Equipamentos de Moagem Ltda., Pomerode, Brazil

NETZSCH (Shanghai) Machinery and Instruments Co., Ltd., Shanghai, China

NETZSCH Mastermix Ltd., Lichfi eld, Great Britain

NETZSCH-España, S.A., Terrassa/Barcelona, Spain

ZAO NETZSCH Tula, Tula, Russia

The NETZSCH Group is an owner-managed, internationally operating technology company headquartered in Germany. Three Business Units – Analyzing & Testing, Grinding & Dispersing, and Pumps & Systems – provide tailored solutions for highest-level needs. Over 2200 employees at 125 sales and production centers in 23 coun-tries across the globe guarantee that expert service is never far from our customers.

The Grinding & Dispersing Business Unit is part of the NETZSCH Group.