8. leistritz extrusionstechnik gmbh.pdf

refreshing extrusion technology

Dispersion and Mixing Characteristics of High Volume and High Torque Twin Screw Extrudersand optimised line layoutMichael Thummert – Head of MarketingLeistritz Extrusionstechnik GmbH, Germany


2 - © Leistritz Extrusionstechnik GmbH - 15.02.2013

Agenda

Factors that have an impact on pigment dispersion and mixing Extruder Configuration Processing Parameters Line Configuration

Dispersion Study with BASF



Energy Balance in the Twin Screw ExtruderPdrive = drive power

Qheat = heating power

Ḣout= enthalpyof product

Ḣin = enthalpy input

Pshafts

Qcool = Coolingenergy

Loss due togearbox and frequency converter

.

.

Ḣevap = Evaporation



Energy Balance in the Twin Screw ExtruderIntroduction of power into the extruder

000

meltingnevaporatiobarrelshafts HHQVUP

VTTcmVUP inoutvTTcm

shafts

inoutv

vV

v

kgkWhe

shafts

v

shaftsinout cm

Vcm

PcmVP

TT

1

vvinout cc

eTT



Energy Balance in the Twin Screw Extruder

Specific energy input

Es= Mact/Mmax * Nact/Nmax * Pnom kW * (0,97)/output kg/h

Es= specific energy inputMact= actual torque Mmax= maximum torque Nact= actual speedNmax= maximum speedPnom= nominal power

The specific energy input is specified in kWh/kg.



Energy Balance in the Twin Screw ExtruderComparison of gearboxes by means of the torque factor [ f ]: unit for power density independent from the extruder size

fMd = T / a 3 [ Nm / cm 3 ] (1)

(1) source: Schenkel, G.: Kunststoff-Extrudertechnik. München, Wien, New York, Carl Hanser -Verlag, 1963



Comparison of Energy InputHP Standard Screw ZSE HP

HP=XX identical screw for the ZSE MAXX Series



Residence Time Distribution

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

0 20 40 60t / s

E(t

) / s

-1

HPXX=HPXX+XX (Igel)XX (Rück)

SEI [kWh/kg]

0,276

0,253

0,275

0,254

0,399

of ZSE HP und ZSE MAXX E (t) :



Four Major Topics for Processing ParametersThere are four main problems that canoccur while running a line:

Volume problems

Air problems

Temperature problems

Torque problems



Volume problems

ventingdegassing feeding zone

feeding

polymer

meltingside feeder

additives/powder

mixing

kneading

mixing

sealing

pressure

building zone

gravimetricfeeder #2

gravimetric feeder #1

Pressure (bar)

How is the material stream split up? Screw geometry / process setup Screw speed



Air problems


feeding

polymer

meltingside feeder

additives/powder

mixing

kneading

mixing

sealing

pressure

building zone



Pressure (bar) Where are seals? Where are venting ports? Does vacuum port work?



Temperature problems


feeding

polymer

meltingside feeder

additives/powder

mixing

kneading

mixing

sealing

pressure

building zone



Pressure (bar)Energy Input

too much energy input by the screw too high screw speed Check specific energy input



Torque problems


feeding

polymer

meltingside feeder

additives/powder

mixing

kneading

mixing

sealing

pressure

building zone



Pressure (bar)Energy Input

too low screw speed Material viscosity – temperature too low Check specific energy input



Extruder Setup ZSE MAXX Premix

Option:Setup with LSB as

Side Vent

Option:Setup with LSB as

Side Vent

Large Feed OpeningLarge Feed OpeningOption:2nd closed barrel when

using a fine screen or UWP

Option:2nd closed barrel when


2-4 barrels for dispersion depending on pigmentand neccessary quality


PremixPremix



Extruder Setup ZSE MAXX Premix Facts Large feed opening for more volume in the feed zone

3 barrels for melting and wetting of the mix

Atmospheric opening can be done with a side feeder less dust!

Depending on desired quality: 2-4 barrels for dispersion

Optional second barrel at the discharge zone in order to create enough

pressure for the use of fine screens and underwater pelletizers

Process length between 36L/D and 48L/D

Screw speeds up to 1,200 rpm

OD/ID = 1.66

Torque factor 15 Nm/cm³ for MB with technical polymers



Extruder Setup ZSE MAXX Split Feed

PigmentPigment PolymerPolymer

Large side feederfor high volume

pigment

Large side feederfor high volume

pigment

Large Feed OpeningLarge Feed OpeningOption:2nd closed barrel when


Option:2nd closed barrel when






Extruder Setup ZSE MAXX Split Feed Facts Larger side feeder for higher mass flow when feeding pigments

Wetting zone with forward venting

Process length between 44L/D and 52L/D

Screw speeds up to 1,200 rpm

Do/Di = 1.66

Torque factor 15 Nm/cm³ for MB with technical polymers



New Barrel for ZSE MAXX

Large Feed Openingapprox. 50% increase!Large Feed Opening

approx. 50% increase!



Twin Operation of the Extrusion LineTwo control panels facilitate control of the line from

two positionsTwo control panels facilitate control of the line from

two positions



28

Dispersion study with BASF

Our Goals:

Transfer of the dispersion properties to the extrusion process

Effects of the dispersion characteristics on:Homogenizing / dispersive pre-mixingFree volume of the extruder (HP / MAXX)Operating parameters (rpm, fill level)

General parameters for optimally dispersed pigments



29

Process variables

Pre-mixingHomogenizing mixing (tumble mixing)Mixing with fast running chopper

Leistritz ZSE 18 HP

Leistritz ZSE 18 MAXXFor both machines:

300, 600, 900 rpmPartially filled and almost filled screwsthroughput limited for the ZSE 18 HP: 3-12 kg/h

Constant:10% MB in LDPE MFI 25, 110°C, premix-screw design



30

Analysis – qualitative overviewPaliotol Yellow K 2270

80

85

90

95

100

105

110

115

120

125

130

135

140

0 30 0 6 00 900 12 00

Ex trud er [rpm]

Co

lou

r St

reng

th [%

]

HP , tumble , part ly filledHP , tumble , filledHP , dispers ive, partly filled

HP , dispers ive, filledM AX X, tumble, part ly f illedM AX X, tumble, filled

M AX X, dispersive , partly filledM AX X, dispersive , filled

Cromophtal Yellow 2GF

8 0

8 5

9 0

9 5

10 0

10 5

11 0

11 5

12 0

12 5

13 0

13 5

14 0

0 30 0 6 00 90 0 12 00

Ex trud er [rpm]

Co

lou

r S

tren

gth

[%

]

H P, tumble , part ly f illedH P, tumble , filledH P, dispersive , partly filled

H P, dispersive , filledM AX X, tumble, par tly filledM AX X, tumble, filled

M AX X, dispers ive, part ly filledM AX X, dispers ive, filled

Cromophtal Yellow 3GNP

8 0

8 5

9 0

9 5

10 0

10 5

11 0

11 5

12 0

12 5

13 0

13 5

14 0

0 3 00 600 90 0 1 200

Ex trud er [rp m]

Co

lour

Str

engt

h [%

]

H P, tumble, par tly filledH P, tumble, filledH P, dispers ive, partly filled

H P, dispers ive, filledM AX X, tumb le , par tly filledM AX X, tumb le , filled

M AX X, dispersive , part ly f illedM AX X, dispersive , filled

Cromophtal Red BNFP

8 0

8 5

9 0

9 5

10 0

10 5

11 0

11 5

12 0

12 5

13 0

13 5

14 0

0 3 00 600 90 0 1 200

Extrud er [rp m]

Co

lour

Str

engt

h [%

]

H P, tumble , par tly filledH P, tumble , filledH P, dispers ive , part ly f illed

H P, dispers ive , filledM A XX, tumb le, p ar tly filledM A XX, tumb le, f illed

M A XX, dispers ive, par tly filledM A XX, dispers ive, filled

Cromophtal Pink PT

80

85

90

95

100

105

110

115

120

125

130

135

140

0 30 0 6 00 900 12 00

Ex trud er [rpm]

Co

lou

r St

reng

th [%

]

HP , tumble , part ly filledHP , tumble , filled

HP , dispers ive, partly filledHP , dispers ive, filledM AX X, tumble, part ly f illed

M AX X, tumble, filledM AX X, dispersive , partly filledM AX X, dispersive , filled

Paliogen Red Violet K 5011

8 0

8 5

9 0

9 5

10 0

10 5

11 0

11 5

12 0

12 5

13 0

13 5

14 0

0 30 0 6 00 90 0 12 00

Ex trud er [rpm]

Co

lou

r S

tren

gth

[%

]

H P, tumble , part ly f illedH P, tumble , filled

H P, dispersive , partly filledH P, dispersive , filledM AX X, tumble, par tly filled

M AX X, tumble, filledM AX X, dispers ive, part ly filledM AX X, dispers ive, filled

Cromophtal Violet GT

8 0

8 5

9 0

9 5

10 0

10 5

11 0

11 5

12 0

12 5

13 0

13 5

14 0

0 3 00 600 90 0 1 200

Ex trud er [rp m]

Co

lour

Str

engt

h [%

]

H P, tumble, par tly filledH P, tumble, filled

H P, dispers ive, partly filledH P, dispers ive, filledM AX X, tumb le , par tly filled

M AX X, tumb le , filledM AX X, dispersive , part ly f illedM AX X, dispersive , filled

Heliogen Blue K 6902

8 0

8 5

9 0

9 5

10 0

10 5

11 0

11 5

12 0

12 5

13 0

13 5

14 0

0 3 00 600 90 0 1 200

Extrud er [rp m]

Co

lour

Str

engt

h [%

]

H P, tumble , par tly filledH P, tumble , filled

H P, dispers ive , part ly f illedH P, dispers ive , filledM A XX, tumb le, p ar tly filled

M A XX, tumb le, f illedM A XX, dispers ive, par tly filledM A XX, dispers ive, filled

• Colour strength a function of rpm• Different processing parameters: premix and extruder type, fill level• Pigments with big impact of processing parameters: up to 35% difference in colour strength• Pigments with low impact: < 10% difference in colour strength

Source: Dr. Ch. Guckel, BASF Schweiz AG; Leistritz Compounding Workshop 2011, Nuremberg



31

Robust, easy dispersible, low influence of machine parameters Dispersibility: excellent

Calendering Effect: medium

Compaction tendency: no

Colour strength in narrowrange: < 10%

Dispersion energy through mixing and increase in rpmdeliver the optimum

ZSE MAXX better develops advantage of dispersive mixing

Cromophtal Red BNFP

95

100

105

110

115

0 300 600 900 1200

Extruder [rpm]

Col

our S

tren

gth

[%]

HP, tumble, partly filledHP, tumble, filledHP, dispersive, partly filledHP, dispersive, filledMAXX, tumble, partly filledMAXX, tumble, filledMAXX, dispersive, partly filledMAXX, dispersive, filled




32

Simple processing,with a “Plus” from pre-mixing Dispersibility: ok

Calendering Effect: no


Colour strength in mediumrange: D ~ 15%

Dispersive mixingshows an advantage

Lower rpm gives longerresidence time (more important than shear:Dispersibility versus Calendering)

Cromophtal Violet GT

85

90

95

100

105

110

0 300 600 900 1200Extruder [rpm]

Col

our S

tren

gth

[%]





33

Straight forward – high throughput with big machine volume Dispersibility: excellent

Calendering Effect: no

Compaction tendency: no Colour strength in medium

range: D ~ 15%

Best results withintensive pre-mixing

Machinery advantage: with ZSE MAXX at high rpm / highthroughput, absence of dispersivepre-mixing gets compensated

Paliotol Yellow K 2270

90

95

100

105

110

115

0 300 600 900 1200Extruder [rpm]

Col

our S

tren

gth

[%]





34

Dispersion properties with highest impact of machinery setup Dispersibility: excellent

Calendering Effect: strong


Pigment develops full colourstrength at short residencetime

Optimum with bigger volume(MAXX) and higher rpm

With no compaction tendency, the excellent dispersibility and potential for colour development is observed during pre-mixing and extrusion process

Paliogen Red Violet K 5011

95

100

105

110

115

120

125

130

135

140

145

0 300 600 900 1200Extruder [rpm]

Col

our S

tren

gth

[%]





36

Summary

The dispersion characteristics of a pigment can be transferred well to the operating conditions of the dispersion process on a twin screw extruder

Results from the dispersion process can be explained with the characteristics of the dispersed pigment

The results help to optimize existing processes and production plants

In many cases, optimum results could be achieved using the bigger free volume of the ZSE 18 MAXX, especially with high throughput

Dispersive pre-mixing showed good results, especially with pigments offering excellent dispersibility and showing no compaction tendency



... any questions???Michael Thummert

Head of MarketingLeistritz Extrusionstechnik GmbH

Markgrafenstr. 29-39D - 90459 Nürnberg

Phone: +49 911 4306 [email protected]

... see films @ www.xxtrusion.tv

8. leistritz extrusionstechnik gmbh.pdf

Documents

leistritz extrusionstechnik gmbh

pigmentand neccessary quality2

basf schweiz ag

excellent calendering effect

zse maxx spl

di spersi ve

compaction tendency

di spers