THE LATEST SIZE
REDUCTION TECHNOLOGYFOR COLOR & MONOCHROME TONERS
By
Katsunori (Carl) Ishito (Nisshin Engineering Inc.)
Kazumi Kozawa (Nisshin Seifun Group Inc.)

CONTENTS¾Introduction•Our company information•Trends in Particle Characteristics•Goal of our company¾Mechanical Mill
•Mechanism&Features•Closed circuit grinding system•Comparison of performance of mechanical mill formonochrome toner with that of conventional jet mill

¾New Jet Mill
•Mechanism&Features•Comparison of performance of new jet mill for color toner withthat of other mills¾Summary

NISSHIN SEIFUN GROUP

Trends in toner
Recent demand for toner• Smaller particle design
10µm5µm•Particle size distribution
BroadNarrow
Less fine particle & coarse particle• Particle shape control
Non Spherical
Spherical

Method of producing toner• Pulverizing process• Chemical process6.4µmCircularity Index: 0.990

8.1µm

13µm

Circularity Index: 0.955

Circularity Index: 0.917

Goal of our company
The design of toner•Pulverized toner ( 5〜10µm )9Monochrome toner・・・mechanical mill or jet mill
9Color toner (especially ,polyester resin)・・・jet mill•Sharp particle size distribution
9Development of grinding and classifying system• Particle shape control
9Circularity Index → 0.97

Mechanical mill 〜Super Rotor〜

Super Rotor SR-25

LinerOutlet
LinerRotor

Inlet

Mechanical mill

Cross sectional view of Super Rotor

Air classifier 〜Turbo-Classifier〜

Powder feed

Classification rotor
Dispersion blades
Dispersion disc
Classification blades
Coarse fraction
outletAir

Auxiliary blades
Scroll casing
Balance rotor
Air flow

Cross sectional view of Turbo-Classifier

Centrifugal Force

Large Particles
Centrifugal Force ＞ Drag Force

Air Flow
Drag Force

Small ParticlesCentrifugal Force ＜ Drag Force

Particle Rotation

Principle of Air Classification(Centrifugal Force Classification)

Grinding & Classifying System
TC-25
For fine classification

TC-25

ProductToner Grinding and Classifying Test Plant

SR-25

Classifier
Bag House

CycloneBag House

Raw Material

FeederBlowerCycloneMechanical
MillClassifier
Blower

Air Cooler
Product

Fine Grinding Process

Fine Classifying Process

Flow sheet of toner grinding and classifying process

Fine particles less than 5µm[vol.%]

Styrene-acrylic toner

28
24

Mechanical mill
Jet mill

20(Closed circuit system)

161284067 8 9 10 11 12 13Median diameter [µm]Relation between the median diameter of product andthe volume percentage of fine particles less than 5µm

Product yield [%]1009080
Mechanical mill
Jet mill

7060

678910 11 12 13Median diameter [µm]Relation between the median diameter and productyield in grinding and classifying

Specific energy consumption[kW h/kg]

7
Closed circuit system

6Mechanical mill
Jet mill

5432
1067 8 9 10 11 12 13Median diameter [µm]Relation between the median diameter of product and specific energy
consumption of closed circuit grinding system

Determination of particle shape of toner
Malvern ; FPIA-2000

Perimeter( Flow Particle Image Analyzer )Circularity index( C.I .)=√(4π*Area)
PerimeterArea≦ 1

NIRECO ; LUZEX
Surface shape factor (S.S.F.)=(Perimeter ) 2
4π * Area≧ 1

Smooth & rounded surface shape

1 (Spherical shape)

Measuring particle shape10µm

S. S. F. = 1.4110µm

10µm

C.I. = 0.927
S. S. F. = 1.41

C.I. = 0.927
S. S. F. = 1.35

C.I. = 0.941
S. S. F. = 1.26(a) Target jet mill(b) Pancake jet mill(c) Mechanical mill

SEM photos of toners

TEMPERATURE CONTROLFOR MECHANICAL MILL
Feed Material: Non-magnetic Toner with Polyester Resin,
D50=500µm (Color Toner)
Grinding Mill : Mechanical Mill with Cooling Air
Product Diameter: 8 µm
Temp. of Mill Outlet: 50 degree C (122 degree F)
Temp. of Cooling Air: from +5 to -40 degree C(from 41 to -40 degree F)

Maximum Throughput [kg/h]

20
Closed Circuit Systemwith Mechanical Mill151050-50Polyester Toner-40(-40 °F)-30-20(-4 °F)-10010(32 °F)

Temperature of Cooling Air [degree C]

Relation between the Temperature of Cooling Air and the Maximum
Throughput of the Mechanical Grinding System

Closed Circuit Systemwith Mechanical Mill8[kW h/kg]

Specific Energy Consumption

10642Polyester Toner

0-50-40(-40 °F)-30-20(-4 °F)-10010(32 °F)

Temperature of Cooling Air [degree C]

Relation between Temperature of Cooling Air and Specific Energy
Consumption of Closed Mechanical Grinding System

Toner manufacturing plant

Filter

FilterFilterMMM

BlowerBlowerBlowerSpiral Type Conveyor
M

BlowerCyclone
LA+Cyclone

LA+BinM

LA-Recycling

Raw Material

BinVibrating
Conveyor

CycloneCooled Air

Cooled Air

Extruding
Pre-Grinding

LA-M
M

Air KnockerHopper
M

M

M

inv

Turbo Classifier(Coarse Classifier)M

inv

Turbo Classifier(Fine Classifier)LA -Additive
Blending
Process

WIC

Constant Feeder

Vibrating
Conveyor

Sampling

Product

Secondary Air
Damperinv
M

Cooled Air
Super Rotor

Cooling Unit

Cooled Water

Toner Manufacturing Process Flow SheetOutline of toner plant
Equipment : Grinding and classifying systems
Feed material : mainly monochrome toner
Product capacity : 30-100 ton / month / line
Product diameter: 8 〜10 µm
Product yield : 85〜93 %New jet mill 〜Super Jet Mill〜

Contents• Super Jet Mill’ features• Performance of SJ for color
toner¾Comparison withÆconventional jet mill,Ætarget jet millÆmechanical mill
• Overall summary
SJ-500Features¾Two stage classification¾Prevent coarse powder from mixing, achieves
narrow particle size distribution.
¾Simple inner structure without moving parts¾Less dead space for internal structure, lesspowder accumulation and adhesion.
¾Easy maintenance and cleaning.

InletGrinding nozzle
OutletOutletInletComp.air

Grinding zone
(1st stage classifying)

Classifying zone
(2st stage classifying)

Comparison between
Super Jet Mill and our conventional jet mill
(1) Screw feeder(2) Jet Mill
(3) Bag house(1)(3)
CompressedAir
Product

Current Jet ( Loop jet type)(2)

Grinding system of Jet MillConventional jet mill ( Current Jet )Relation between particle size distribution of product and mixture
rate ( Color toner with polyester resin)Super Jet Mill

Super Jet Mill achieves
precise particle size distribution!

Relation between particle size distribution of product and mixturerate( Color toner with polyester resin)Current Jet

Super Jet MillSEM photos of color toners ( Median diameter : 7µm )Comparison between SJ and a target jet millFrequency [vol %]SJTargetjet mill

diameter [µm]Type ofJet millMediandiameter
[µm]

Over
16µm
[ vol%]

Under
5µm[pop%]

SJ-500

9.8

1.57

48.5

Target jet mill

9.5

3.80

51.9

Comparison of Mechanical Mill and Super Jet Mill
(1) Screw feeder(4) Bag house(1) Screw feeder(2) Mechanical Mill (5) Classifier(3) Cyclone(6) Blower(4)(2) Super Jet Mill
(3) Cyclone(4) Bag house

(4)
(4)

(5)

(3)

(1)
(1)
(6)
(3)

(6)

(3)

(2)
(2)

Closed circuit grinding system
Grinding system of Super Jet Millof Mechanical MillTest condition
Mechanical grinding system
Raw Material: Color & Monochrome toner
Mechanical mill : SR-15 ( rotor diameter φ150)
Rotational speed : 13,000〜14,000 min-1
Air flow rate : 1.5 m3/min
Throughput : 〜 1 kg/h
Air classifier : TC-15 ( rotor diameter φ150)
Rotational speed : 5,000〜7,000 min-1
Air flow rate : 2.5 m3/min

Grinding system of Super Jet Mill
SJ-500

Air Pressure : 0.6 MPa ( 0.55m3/min)Throughput : 〜 1 kg/h

Relation between the median diameterand the population percentage of fine particles less than 3µm( Color toner with polyester resin)SEM photo of color toner

C.I.= 0.944

C.I.= 0.943

Mechanical grinding system

Super Jet MillRelation between the median diameter of productand specific energy consumption( Color toner with polyester resin)Effect of fine classification
on particle shape
Color toner with polyester resin

TC-15
Rotational Speed : 10,000 min-1
Air Flow Rate : 2.1m3/min
Throughput : 1.8kg/h

Before fine classification
C.I.=0.943

After fine classification
C.I.=0.959

Monochrome toner

Mechanical mill (6.1µm)

Super Jet Mill (6.2µm)
Relation between the median diameter of productand specific energy consumption( Monochrome toner with Styrene-acrylic resin)Comparison of our toner and chemical toner
Chemical toner
D50= 6.4µm
Coefficient of
Variation = 21.5
Circularity Index= 0.990
Pulverized toner
D50= 6.3µm
Yield= 72 %Coefficient of
Variation = 17.9
Circularity Index= 0.956

Line-up
PulverizerThroughput

TypePowerconsumption〜2 kg/h

SJ-500〜7.5 kW(10HP)〜10 kg/h

SJ-2500〜22 kW(30HP)

SJ-10K〜90 kW(120HP)(〜120 kg/h) (SJ-30K)(〜190 kW)
(250HP)〜40 kg/hFine classifier
TypePowerconsumption(with blower)

TC-15〜3.7kW
(5HP)

TC-25

TC-40

〜13 kW(18HP)
18.5〜37 kW(25 〜50HP)

Summary¾Mechanical Mill
(for monochrome toner with diameter more than 5.5-7µm)① It can easily prevent over-pulverization→ narrow particle size distribution→ less power consumption② It produces spherical toner accepted in market without
additional treatment for rounding

¾New Jet Mill -Super Jet Mill
(for color & monochrome tonerwith diameter less than 7µm)
① It can prevent the mixture of coarse particles→narrow particle size distribution→easy to control particle size
② It has less dead space for internal structure→less the powder accumulation and adhesion③ It produces spherical color toner as same as toner groundby mechanical mill