004 - Efficient Foam Production

 

Adjusting Foam Production with Maxfoam ®  Machines for Best Efficiency and Minimized Production Issues

Ruediger Landers

 

Machine Types and Foam Types Foam type

Standard ether Technical ethe etherr foam foam

Trough

Laydown

CO2

MC

√

√

√

√

  √

√

(√)

(√)

√

√ √ √

(√)

(√)

(√)

(√)

√

(√)

 

Ester

High

Low

Pressure

Pressure

√

√

Viscoelastic

HR foam

Ultra-low density

 

√ √

√ √

√

√

(√) √

 

 

√

 

Which Machinery for which Foam Plant? < 1000 mt/a

1000 mt/a –   5000 mt/a

5000 mt/a –  10000 mt/a

> 10 000 000 m mt/ t/a a

Box foaming Low pressure machines High pressure machines Conti. VPF Vertifoam

- If technical foams should be produced, a high pr pre essure machine is required! - If just foams for comfort foams should be produced, a low pressure machine is co com mme merrci cial ally ly mo more re vi via abl ble e. - Roughly 80% of all c co ontinouse machines on tth he world are low pressu pre ssure re mac machin hines. es.

 

1. Theory Part

 

Block Shape Appearance •

Generally most of the foaming processes struggle with the generation of a proper rectangular block shape.

•

Holding back of the rising foam from the side si de walls generates the dome effect (Movement of the foaming material versus the static side wall).

•

Dome forms when the viscosity of the reaction mixture is rising.

•

One of the major issues in box foaming but also in continuous foaming technologies.

•

Reduces the foam yield significantly (increases scrap rate)

Movement of the rising foam relative to the side walls causes dome shape Dome formation during block rise

 

Block Shape Improvement

Dome shape foam block

Tec echn hnic ical al m mea easu sure res s to redu reduce ce the the dome dome effe effect ct:: a) Flat to top s sy ystem (top lid lid)) b) Pulling ing side paper/foil upwards (mov (m ovin ing g si side de wal alls ls up upwa ward rds) s) a) Moving bottom downwards

Ideal square foam block

 

Tec echn hnol olog ogie ies s to en ensu sure re th the e Ho Homo moge geno nous us Age of of Mat ater eriial in the Cro ross ss--Se Sect ctiion of a Foam Blo lock ck

Target: same age in a block cross-section

(Picture modified from image in DOW Handbook)

It is a theoretical target. The reality could be checked when the colour of a formulation is changed. Nevertheless, especially for high viscous formulations it might be of importance to get as close as possible.

 

Flow Pattern in Liquid Lay-Down

Issues in filling wider conveyors Different age of material in a cross-section

 

Maxfoam ®  Process

In the figure: 100% expansion to bottom In reality more often: 70 % expansion to bottom for trough and 50-60% for liquid laydown

 

Block Shape Improvement

Fall plate system (bottom lowering)

Flat top system

 

Flow Direction in Continouse Machines

 

Flow Direction in Continouse Machines - Ex Expa pans nsio ion n to th the e top top -

1.

3.

2.

4. = split zone

Material at the sides gets stucked due to adhesion to side walls

 

Flow Direction in Continouse Machines - Exp Expans ansion ion to the Bot Bottom tom 1.

2.

3.

4.

= potential split zone

Material at the sides gets stucked due to adhesion to side walls In general less severe split situation with a bottom lowering as gravity helps to fill the new empty space

 

Rise Profil versus Fall Plate Setting Blow off point

Rise profil

Fall plates setting Splits, shoulders

dome formation

OK

 

Relative Movement of Foam versus Side Sid e Wall Walls s – Wron rong g Timi Timing ng Splits, typically related to expansion after blow off, sometimes also associated with flat top processing

Movement of side walls versus foam too early

Ideal block shape, side wall movement synchron to foam expansion

Movement of side walls versus foam too late Splits, typically where bottom paper ends, sometimes also higher

 

Relative Movement of Foam versus Side Sid e Wall Walls s – Wron rong g Heigh Heightt Only slight or almost no splits

Movement of side walls versus foam too low

Ideal block shape, side wall movement equivalent to foam height* * = often 70% for for troug trough, h, 50 – 60% for lay lay-dow -down n

Movement of side walls versus foam too much

 

Relative Movement of Foam versus Side Walls

Timing of movements: adjustment against blow–o Timing blow–off ff line: a little bit behind last fall plate: a mark is always required at both side of the tunnel where the last fall plate ends. Difficult to predict / control

small scale trial required or incremental formulation development

Height of fall plate system: adjustement by block height (less than max. foam height: between 66% and 100% of foam height. Easier to predict / calculate

 

Typical Rise Profiles and Consequences for Fall Plate Setting

Idea: Lab foaming could be used to predict machine setting Issue: different temperature profile lab foam versus machine foaming Solution: Master curve in the laboratory

 

Laboratory Rise Profile Analysis to Predict correct Fall Plate Setting 150,00

100,00

50,00    ]    %    [    t    h   g    i   e    h   m   a   o    f

0,00 0

20

40

60

80

100

120

140

Trough -50,00

-100,00

-150,00

time [s]

Prediction of correct fall plate setting + conveyour speed

 

Ideal Fall Plate Setting

Picture generated by using FoamKit 2000 software, www www.tg-cellsoft.com .tg-cellsoft.com

 

Not Optimized Fall Plate Setting

Picture generated by using FoamKit 2000 software, www www.tg-cellsoft.com .tg-cellsoft.com

Issue: flow related issues like underrunning

 

Typical Rise Profils and Consequences for Fall Plate Setting

 

Analysis of typical Rise Profils and Consequences for Fall Plate Setting Formulations without clear blow-off

Formulations with early blow-off

Formulations with a very long rise time

Formulations with a very with very fast expansion

Formulations with a very slow expansion Formulations with a very short cream time

 

Anchor Points: Blow-Off Line and Creaming

creaming

Picture taken from DOW Handbook

Blow line (Needs to be marked on the tunnel)

 

Timing in Foaming Pour urin ing g ti time me Po Cream time

Maxfoam process

Laboratory Box foam

Material Flow is leaving through mix head pipes

End of Pouring mixing

0s

Material Time Transfer enters onto in trough trough conveyor

Pouring Creaming Foam rise finished starts

5s

10 s

(time numbers are just for example)

Rise Tim Rise ime e Foam Rise

Foam Rise

Blow off

Blow off

125 s

Time scale

 

Calculations I t mix head  t  pipes

=

=

V    mix head  ⋅

liquid 

tp ⋅  ρ  V     pipes liquid 

For calculation of pipe volume:

tp

 

 xsaftey dis tan ce

 

t trough

=

  trough ⋅ V  tp

t rise t mix head 

=

liquid 

t  pipes +  t trough

= Time in pipes [s]

t trough

= Time in trough [s]

t rise V mix head 

V  pipes

t safety dis tan ce   

V trough

= Rise time (from leaving mix head till blow-off) [s] = Volume mix head [l] =

vconveyor  =

 x blow − off  v conveyor 

= Volume trough [l]

 ρ liquid  = Density liquid reaction mixture [kg/l]

V cylinder  = Volume of a cylinder r 

= Time on conveyor till blow-off [s]

=

t conveyor  blow − off  

+ t conveyor  blow− off 

= Time in mix head [s]

t  pipes

t conveyor blow− off 

(this is not 100 % correct, as density starts to decrease)

2

V cylinder  = Π  ⋅ r  ⋅ L

=

 L =  xblow −off 

Radius of cross-section of a cylinder length of a cylinder

= Blow-off position (from trough) [m]

vconveyor  = Conveyor speed [m/min] to be transferred into [m/s]

Volume pipes [l]

tp

=

Through put [kg/min]

 

Calculations II tp =

w⋅ h ⋅  

 foam

⋅ vconveyor 

 fy

 fy =

mass foam

 pphpraw materials =

 

massraw materials

 xblow−off 

−  pphp water  ⋅

44 18

−  pphp physical blowing agent 

 pphpraw materials

=

vconveyor  ⋅ t rise  −  

 ρ liquid  ⋅  fy

⋅

(V 

 pipes

+ V trough

w ⋅ h ⋅ ρ  foam tp

=

Through put [kg/min]

w= h=

 pphpraw materials

=

Height block [m]

= Final mass of foam [kg]

raw materials

and an d co conv nvey eyor or sp spee eed. d.

Parts all raw materials in formulation form ulation per hundert parts polyol [ ]

 pphpwater 

= Parts water in formulation per hundert parts polyol [ ]

 pphp physical blowing agent  = Parts physical blowing agents in formulation per hundert parts polyol [ ]

 fy = Foam yield [ ]

mass

Relation between blow-off position

Width conveyor [m]

 ρ  foam = Density final foam [kg/m³]

mass foam

)

= Mass of raw materials [kg]

(all other variables defined on previous page)

 

Calculations III

vconveyor  =

or:

 ⋅  xblow 

1

t rise ⋅

V trough  = w h

⋅

 ρ  foam

 ρ liquid  ⋅  fy

after knowing vconveyor :

⋅

− off 

⋅

[v 

tp

+   ρ liquid   fy ⋅   w ⋅ h ⋅ ρ  foam

 

t 

conveyor  ⋅ rise

=

 fy

]

−  xblow−off  −  V pipes

w ⋅ h ⋅ ρ  foam  

 (V  pipes + V trough ) 

⋅

vconveyor 

Calcul ation on of Calculati conveyor conve yor spe speed. ed.

Calcul ation n of Calculatio trough tro ugh siz size e (Caution: (Cauti on: cream time must also fit!)

A simulation tool helps a lot for the calculations!  

Mismatch actual formulation with reference rise profile 150,00

Blow-off position

position

Reference rise ri se pr prof ofilile e

100,00

Actual rise profile

50,00    ]    %    [    t    h   g    i   e    h   m   a   o    f

Blow-off

0,00 0

20

40

60

80

Trough -50,00

-100,00

-150,00

time [s]

Potential issue: dome formation, top splits

100

120

 

Potential Adjustements

1. Adjustement Adjustement of machinery - chan change ge fall plate syste system m sett settings ings - cha change nge tro trough ugh size - cha change nge tthro hrough ugh-pu -putt - chan change ge o off conve conveyor yor speed

2.- Adjustement Adju stement of foam chang change e of a amine mine ((& & tin tin))formulation cata catalyst lysts s - cha change nge o off tin c cata atalys lystt - chang change e of raw ma materia teriall temper temperature atures s

 

Influence of Machine Adjustements Adjustements - Fa Fall ll pl plat ates es 150,00

100,00

50,00    ]    %    [    t    h   g    i   e    h   m   a   o    f

Trough

0,00 0

20

40

60

80

-50,00

-100,00

-150,00

time [s]

100

120

140

Posi Po siti tio on of piv ivo ot poi oin nts rem emai ain ns th the e sa sam me!  

Computer controlled fall plate adjustement onfoaming height measurementbased during Basic assumption: top of conveyor is a flat line or any kind of optimum profile Height sensors (ultra sonic or laser based)

actuators

Required for auto-adjustment auto-adjustment:: 1. Height measurement atop the foam block 2. Movable Pivot points (hydraulic or screw driven height change) 3. Control unit for continuous adjustment

 

Influence of Machine Adjustements Adjustements - Co Conv nvey eyor or spe speed ed 150,00

100,00

Lower conveyor speed 50,00    ]    %    [    t    h   g    i   e    h   m   a    f   o

Higher conveyor speed 0,00 0

20

40

60

80

-50,00

-100,00

-150,00

time [s]

100

120

140

Foa Fo am ri rise se cu curv rve e is st stre rech ched ed / co comp mprres esse sed d / blo block ck he heig igh ht ch chan ange ges s  

Influence of Machine Adjustements Adjustements - Tro roug ugh h siz size e150,00

100,00

Bigger trough 50,00    ]    %    [    t    h   g    i   e    h   m   a    f   o

Smaller trough 0,00 0

20

40

60

80

-50,00

-100,00

-150,00

time [s]

100

120

140

Foam rise curve is shifted left /right!  

Influence of Machine Adjustements Adjustements - Th Thro roug ugh h put put 150,00

100,00

Lower throughput

50,00    ]    %    [    t    h   g    i   e    h   m   a   o    f

Higher throughput 0,00 0

20

40

60

80

-50,00

-100,00

-150,00

time [s]

100

120

140

Foam block is is getti tin ng higher/low owe er and rise curve is shift ftiing left /right!  

Influence of Formulation Adjustements Adjustements - Cha Change nge of Am Amine ine Cata Cataly lyst st Level Level 150,00

100,00

Higher amine loading 50,00    ]    %    [    t    h   g    i   e    h   m   a   o    f

Lower amine loading 0,00 0

20

40

60

80

-50,00

-100,00

-150,00

time [s]

100

120

140

Foam rise cu currve is strech che ed / co compressed and shift fte ed!  

Influence of Formulation Adjustements Adjustements - Chan Change ge of Raw Raw Material Material Tempe Temperature ratures s150,00

100,00

Higher temperature 50,00    ]    %    [    t    h   g    i   e    h   m   a   o    f

Lower temperature 0,00 0

20

40

60

80

-50,00

-100,00

-150,00

time [s]

100

120

140

Foam rise cu currve is strech che ed / co compressed and shift fte ed!  

Influence of Formulation Adjustements Adjustements

Aside of changing the time axis of the foam f oam expansion also the shape could be changed by special catalysts: - block cke ed amines (acc cce elerating reaction at a certain sta tag ge) - Re Reac acti tive ve ca cata taly lyst sts s (s (slo low win ing g dow own n rea eact ctio ion n due to im immo mobi bililisa sati tio on) 150,00

100,00

   ] 50,00    %    [    t    h   g    i   e 0,00    h 0   m   a   o    f

-50,00

-100,00

-150,00

Blocked amine catalysts (catalytic activitity increases) reactive amine catalysts (catalytic activitity decreases) 20

40

60

80

100

120

140

time [s]

 

Options to Synchronize Formulation and Machine Compar Comp arin ing gan new ew form formul ulat atio ion n wi with th an es esta tabl blish ished ed formul for mulati ation on by box box lab lab foa foamin ming. g. Incremental Increment al formu formulatio lation n an and d mach machin ine e ad adju just stem emen entt

Adjusting formu Adjusting formulatio lation n to ma mattch box rise rise profi rofile le of refe refere renc nce e + keep keepin ing g machin mac hine e set settin tings gs

opti mize zed d fo form rmul ulat atio ion n+ optimi adju ad juste sted d ma mach chin ine e se sett ttin ings gs

Calcul Calc ulat atio ion n of ri rise se pr prof ofilile e an and d mach machin ine e pa para rame mete ters rs

Adjust Adju stin ing g ma mach chin ine e sett settin ings gs fr from om co comp mpar aris ison on of bo box x ri rise se profiles

 

Limitations of Laboratory Predictions Assumption: differences between between fformulations ormulations are similar in lab box foaming and real production - This assu assumptio mption n might just be pa partiall rtially y true - Final adjustem adjustement ent needs to be done in the production run -- Alternative But the la lab b approa resultsch allow at least to get relative clo close se to the fin final approach would to „develop“ „develop“ foam formulations in al small smoptimum all steps and adjusting the conditions incrementally, but basic knowledge how to adjust either machine or formulation is anyhow required - Helpful learn learning ing tool: Fo FoamKit amKit softw software are (ww (www w.tg-cellsoft.com)

Butt just Bu just sta start rtin ing g th the e ma mach chin ine e an and d no nott anal analy yzi zing ng the ch the char arac acte terris istc tcs s of a new new fo forrmu mula lati tion on in ter terms ms of rise profile is simply burning money by producing waste…

 

Nucleation

Nucleation foradding low pressure is head mainly supported and controlled by gas/air machines into the mix Different technologies technologies to add the air (into mix head, manifold or silicone stream) Di Difffere ferent nt ai airr load loadin ing g leve levels ls for for di difffere ferent nt fo form rmul ulat atio ions ns:: - Standard ether - Ultra low densities (much higher) - HR foam (much higher) - Visco foam (higher) Issue: pin holes appear if too much gas / air is used Gas / air pressure needs to be constant! Solubility of gas in reaction mixture should be as low as possible (no CO2, but N2) Nucleation is also linked to the used stirrer and it‘s speed Nucleation support is also possible by special additive solutions

 

Special Retrofits Nucleation

Gas Ga s lo load adin ing g sta stati tion on fo forr TD TDI, I, po poly lyol ol Gas loading of TDI, polyol could be used to control nucleation without changing air addition into manifold or any stream of the machine. Limitation for low pressure machines: Lower raw materials pressure leads to lower solubility of gases.

Stabilizer Mixer (Frothing) To reduce pin holing issues gas loading of the stabilizer is possible by pre-mixers. Gas loading and nucleation could be increased significantly.

 

Special Retrofits Paper Peeling

standard design

optimized design (reduced friction –  less cracks)

How would you remove an adhesive tape fr fro om your sk skiin with lowest irrita tattion?  

Special Retrofits Process Liner “Back Winding” Target: Provide a delamination of plastic foil and paper

Standard placement of process liner roll

Process liner roll removed and turned around

Plastic foil separated and winded around the roll

(Technology recommended by Mondi)

Cutting of the plastic foil to the same length as paper

Inserting into the process liner feed system for the conveyor

 

Special Retrofits Side Walls

Static Side Walls

Moving Side Walls & other modifications of side walls

Usage of static side walls might suffer from the following issues:

-

Mo Movi ving ng si side de walls alls mi migh ghtt be be iins nsta talllled ed to avoid those issues.

-

He Heat atin ing gu up po off the the si side de wall all m mat ater eria iall and consequently of the foam, foam reaction is accelerated and results in defects

-

Co Cool olin ing g sy syst stem em ffor or si side de wal alls ls mi migh ghtt be added (either a fan blowing air against the back side or fixing of water pipes to metal side walls

-

If foam foam is no nott s sho how wing ing s suf uffi fici cien entt blow-off an expansion after the blowoff might block the foam block transport.

-

Ex Exch cha ang nge eo off th the s sid ide ew wal alls ls by materials less heat capacitive

 

Other Retrofits

Tools for an automatic measurement of raw material flow are an essential tool to check that the correct amount of materials are entering the mix head. It makes foaming more reliable and safer s afer.. It allows for example an automatic stop once the mass flow of MC is too low.

Temperature control of raw materials is not only crucial for safety but also for ensuring reliable foaming results

 

2. Practical part Typical Issues in Running Maxfoam ®  Machines

 

2. Practical part Splits

Ove-Andre

Strand-Larsen    

Splits because of Insufficient Crosslinking Discontinous:

Box foaming

X

Failure:

Continous:

Liquid laydown

X

Continous:

Maxfoam ® 

X

• The These se s spli plits ts a are re iinter nternal nal.. They They are detected when the block is cut.

Continous:

Vertifoam

X

Reason: • Foa Foam m is ve very ry ope open n and is n not ot en enough ough cro crossss-lin linked ked.. Stannous octoate slightly beyond the limit quantity Counter Measures: • Sli Slight ght inc increa rease se of s stan tannou nous so octoa ctoate te • Che Check ck qua qualit lity yo off s stan tannou nous s octo octoate ate • Add cro crossss-lin linker kers s / chai chain ne exte xtender nders s Limitation/Comment:

 

Splits because of Insufficient Crosslinking

 

Splits because of Shear between Walls and Rising Foam Discontinous:

Box foaming

X

Failure:

Continous:

Liquid laydown

X

• Spl Split it from from cor corner ner or fr from om side to ce cente nterr

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Reason: • Foa Foam m cou could ld not wi withst thstand and fforc orce e dur during ing b blow low of offf Counter Measures: • Incre Increas ase e cr cross oss-l -lin inki king ng • Higher tin • Mo More re ch chai ain ne ex xtend tender er • Mo More re cros crosss-li link nker er • High ghe er index

Limitation/Comment: • Foa Foam m po poros rosity ity nee needs ds tto o be o open pen e enou nough gh to allow stronger cross-linking

 

(box foam)

Corner Splits & Side Splits

 

Relative movement of foam versus side si de wal walls ls – wr wron ong g timin timing g Splits, typically related to expansion after blow off, sometimes also associated with flat top processing

Movement of side walls versus foam too early

Ideal block shape, side wall movement synchron to foam expansion

Movement of side walls versus foam too late Splits, typically where bottom paper ends,

sometimes also higher

 

Corner Splits (from conti production)

& Side Splits

 

Side Splits

 

Strong Side Splits Discontinous:

Box foaming

Continous:

Liquid laydown

X

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Failure: • Stro Strong ng Side Side Spli Splits ts Reason: • Am mix ix of che chemic mical al an and d mech mechani anical cal rreaso easons. ns. The amount of the amine is too low and/or the output is too high and/or the conveyor speed is too high • Bui Buildld-up up of m mate ateria riall iin n th the e tr trough ough • Mec Mechan hanica icall rea reasons sons:: Th The e peel peeling ing o off the pap paper er is too slow or in the wrong angle • Eit Either her ttear ear st stren rength gth too llow ow or a adhes dhesion ion of pap paper er too high Counter Measures: • Dec Decrea rease se c conv onveyo eyorr spe speed ed & rreduc educe e ou outpu tputt • Later p pe eeling • Incr Increa ease se am amin ine e • Usage of pap paper-fo er-foil-la il-laminat minate, e, just p paper aper is pee peeled led o off ff Limitation/Comment:

Picture from: Arco Chemical Company, Flexible Polyurethane Slabstock Foam – An Overview of the Technology an Troubleshooting Guide, by R. Schiffauer

 

Technologies for a Clean Trough

Clean trough during the run: - Kn Knif ife e ffor or re remo mova vall of of re resi sidu dues es - Limit duration of runs

Clean trough after the run: - Plastic liner - Coating

 

2. Practical part Machine Mach ine Temper emperatur ature e Issues

Ove-Andre

Strand-Larsen    

Thick Top Skin Discontinous:

Box foaming

X

Failure:

Continous:

Liquid laydown

X

• Thic Thick k top top skin skin (> 1 m mm) m)

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Reason: • Inst Instabi abilit lity y of gas bu bubbl bbles es at th the e surf surface ace d duri uring ng foam rise due to temperature gradient • Temper emperatur ature e of the air in the ffoam oam p plant lant ttoo oo low (winter) • Ge Gellllin ing g rrea eacti ction on too too s slo low w Counter Measures: • Hig Higher her tem temper peratu ature re in th the e foa foam m pl plant ant • Us Use eo off top top pa pape perr /fo /foil il • May Maybe be IR ir irrad radiat iation ion /he /heati ating ng fr from om th the e top Limitation/Comment: • if Cou Could ld walls al also so ap appear at th the eare sid sides es tthe he b bott ottom om side orpear conveyor tooorcold

 

Thick Bottom Skin Discontinous:

Box foaming

X

Failure:

Continous:

Liquid laydown

X

• Thic Thick kb bot otto tom ms skin kin (> 1 m mm) m)

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Reason: • Instabi Instability lity of gas bubbles at th the e bott bottom om surface during foam rise due to temperature gradient • Temper emperatur ature e of the conv conveyor eyor in the ffoam oam plant ttoo oo lo low w (winter) • Ge Gellllin ing g rrea eacti ction on too too s slo low w Counter Measures: • Highe Higherr te tempera mperature ture in th the e foa foam m pl plant ant (conv (conveyor) eyor) Limitation/Comment: • Cou Could ld al also so app appear ear a att the si sides des iiff side w wall alls s are to too o cold

 

Condensation lines Discontinous:

Box foaming

X

Failure:

Continous:

Liquid laydown

X

•Condensation lines in the lower part of the block

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Reason: •Maybe insufficient mixing •Low temperature of the pour plate / conveyor c onveyor (most often) Counter Measures: •Higher temperature in production hall / pre-heating of pour plate / conveyor •Higher mixer speed •Addition of emulsifier / better emulsifying stabilizer Limitation/Comment:

 

Condensation lines

 

Pockets / Conus Splits Discontinous:

Box foaming

X

Failure:

Continous: Continous:

Liquid laydown Maxfoam ® 

X X

• Co Conus nus lilike ke s spl plit its sw wit ith h sma smallll rrol olls ls insi inside de

Continous:

Vertifoam

Reason: • After a long product production ion convey conveyor or and tunnel wall walls s are heated. The foam mixture is already cured at the bottom and sides but still rising in the middle Counter Measures: • Coo Cooll th the e co conve nveyor yor and tun tunnel nel wal walls ls Limitation/Comment: • Pr Produ oduct ctio ion ns sto top p rrequ equir ired ed

•

••

•

•

••

••

•

• Mor More e eff effici icient ent co cooli oling ng equ equipm ipment ent iis s requi required red • More often with st static atic side w walls, alls, lless ess oft often en w with ith mov moving ing side walls

 

2. Practical part Under- or OverStabilization of Formulation

Ove-Andre

Strand-Larsen    

Collapse Discontinous:

Box foaming

X

Continous:

Liquid laydown

X

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

X

Failure: • Collapse Reason: In most cases: • Not en enough ough stabil stabilizer izer and/or the use used d stab stabilize ilizerr iis s too weak and/or stannous octoate is too low or partial inactive Counter Measures: • Che Check ck rraw aw m mater aterial ials s iin n han hand d ba batche tches s • Ch Check eck dosag dosage eo off all all liline nes s • Ch Check eck for for def defoa oami ming ng con conta tami mina nati tion ons s • Use m more ore stab stabili ilizer zer or a hi highe gherr act activ ive e one one.. • Use mo more re sta stannou nnous s octo octoate ate,, hi higher gher iinde ndex, x, mo more re cross-linker Limitation/Comment: Caution! Risk of self ignition in

collapsed foam!  

Collapse

 

Bottom Densification Discontinous:

Box foaming

X

Failure:

Continous:

Liquid laydown

X

Continous:

Maxfoam ® 

X

• Lay Layer er of dens dense e fo foam am a att th the e bot bottom tom of th the e bun, this layer is distinctly d istinctly separated from the normal foam

Continous:

Vertifoam

Reason: • St Stabi abililizer zer too too lo low w or ttoo oo w wea eak k • Bot Bottom tom d densi ensific ficati ation on d due ue to st stron rong g set settli tling ng Counter Measures: • Incr Increas easing ing tthe he sur surfact factant ant lleve evell or more pot potent ent on one e • Ma Mayb ybe eh hig ighe herr ti tin n lev level el Limitation/Comment:

 

Bottom (stabilizer too low)

Densification

 

Bottom Blow Off Discontinous:

Box foaming

X

Failure:

Continous:

Liquid laydown

X

• Spl Splits its o orr cav cavern erns s in b bott ottom om zone wi with th shiny surface

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Reason: • Foa Foam m ttoo oo ttigh ight, t, blo blow w of offf to bot bottom tom • Too hi high gh am amount ount of sta stabilize bilizerr and/or and/or stannou stannous s octoate Counter Measures: • Red Reducti uction on stan stannous nous octo octoate ate step by s step tep (5 - 10 % %)) • Mayb Maybe e redu reduction ction of sta stabilize bilizerr, reductio reduction n of index index,, cross-linker,, maybe more blow amine catalyst cross-linker Limitation/Comment:

 

Bottom Blow Off

 

Shrinkage Discontinous:

Box foaming

X

Failure:

Continous:

Liquid laydown

X

• Shrinkage

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

X

Reason: • Foam too titight • Cooling o off ga gas • Ga Gas se exc xcha hange nge wi with th a air ir (C (CO O2 penetrates faster than air) • Res Result ults s in und underer-pre pressu ssure re iiff cell cells s are cl closed osed Counter Measures: • Op Open en u up p ce cell ll s str truc uctu ture re • Re Reduc ducti tion on o off sta stann nnou ous s oct octoa oate te • May Maybe be red reducti uction on of stab stabili ilizer zer • May Maybe be mor more eb blow low ami amine ne cata catalys lystt • May Maybe be re reduct duction ion of in index dex o orr cro crossss-lin linker ker

 

Shrinkage

 

Gas Bubbles at the Block Side (for HR foam) Discontinous:

Box foaming

Continous:

Liquid laydown

Continous:

Maxfoam ® 

Continous:

Vertifoam

x

X

Failure: • Ga Gas s bu bubb bble les sa att th the e si side des s Reason: • Indi Indicat catio ion n fo forr a ti tight ght HR ffoa oam m Counter Measures: • Reduce Tin • Re Redu duce/ ce/ incr increas ease eH HR R sil silic icon one e • Reduce DEOA Limitation/Comment: •

For For hi high pres pressu surre m mac achi hine nes sa als lso o sometimes in lower part of the block

•

Ofte Often na allso with s sig igns ns of sh shri rink nkag age e

 

Gas Bubbles at the Block Side (for HR foam)

Phot Photos os fr from om HR box foaming

 

Balance Between Overstabilization and Understabilization

Picture from: Book: Dow Polyurethanes, Flexible Foams.

 

2. Practical part Overstabilization by Stabilizer

Ove-Andre

Strand-Larsen    

„Finger Prints“ Failure:

Discontinous:

Box foaming

Continous:

Liquid laydown

X

• Pl Plaqu aques es a are re p pul ulle led d out o off the ffoa oam m

Continous:

Maxfoam ® 

X

• Sid Side e blow o off ff mi might ght b be e the rea reason, son, pea pealin ling g mak makes es it visible

Continous:

Vertifoam

Reason: • Adh Adhesi esion on be betwe tween en pap paper er an and d foa foam m is hi highe gherr tha than n in the foam • Foa Foam m blo blows ws to th the e sid side e (spl (splits its b belo elow w the sk skin in be becom come e visible during peeling) Counter Measures: • Other paper • Use low lower er amo amount unt of stab stabili ilizer zer • Us Use e a llow ower er ac acti tive ve on one e Picture from: Arco Chemical Company, Flexible Polyurethane Slabstock Foam – An Overview of the Technology an Troubleshooting Guide, by R. Schiffauer

• Red Reduce uce ttin, in, iindex ndex,, cro crossss-lin linker ker loa loadin ding g Limitation/Comment:

 

2. Practical part Peeling Stress

Ove-Andre

Strand-Larsen    

Vertical Side Splits on Block Sides Failure:

Discontinous:

Box foaming

Continous:

Liquid laydown

X

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

• Vert ertica icall Si Side de Spl Splits its on b both oth si sides des o off the bl block ock Reason: • The a amou mount nt of tthe he sta stabil bilize izerr is to too o hig high h or the u used sed stabilizer is too active. Foam blows to the side / bottom, foam structure deficiency becomes visible by peeling • Alter Alternativ natively ely adhesio adhesion nb betwee etween n si side de pa paper per and ffoam oam too strong Counter Measures: • Us Use e le less ss a amo moun untt of s stab tabililiz izer er • Us Use e a llow ower er ac acti tive ve on one e • Red Reduce uce ttin, in, iindex ndex,, cros cross-l s-link inker er lload oading ing Limitation/Comment:

 

Vertical Side Splits on Block Sides

 

Vertical Splits Discontinous:

Box foaming

X

Failure:

Continous:

Liquid laydown

X

• Verti ertica call ro roug ugh h foa foam m sp splilits ts

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Reason: • Sid Side e wal walls ls are rremo emoved ved to too o fas fastt (bo (box x foam foaming ing)) • Sid Side e pape paperr is pee peeled led of offf to ear early ly (C (Cont onti. i. fo foami aming) ng) + Insufficient cross-linking Counter Measures: • Hi High gher er cr cross oss-l -lin inki king ng llev evel el • More tin • Add c cros ross-l s-link inker er,, ch chain ain-ex -exten tender der • Lat Later er rem remova ovall of sid side ew wall alls s / pa paper per

Limitation/Comment:

 

Vertical Splits (Conti)

 

Top Splits on the Block

Discontinous:

Box foaming

Continous:

Liquid laydown

X

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Failure: • Top S Spli plits ts on tthe he ttop op of the blo block ck Reason: • The ttop op pa paper per has ttoo oo m much uch a adhe dhesio sion n or tthe he te tear ar strength of the foam is insufficient. T Top op splits are pulled into the top skin due to paper removal Counter Measures: • Use a co combi mbinati nation on of P PE E foi foill with with pap paper er • Pul Pulll the p pape aperr of offf at a llate aterr sta stage ge o orr red reduce uce conveyor speed Limitation/Comment:

 

2. Practical part Blow-offf Issue Blow-of Issue with Flat Top

Ove-Andre

Strand-Larsen    

Separation of Top Layer Failure:

Discontinous:

Box foaming

Continous:

Liquid laydown

X

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

• Top la laye yerr se sepa para rati tion on Reason: • Gas co could uld n not ot le leave ave tthe he fo foam am as th the e top pa paper per / ttop op foi foill is strongly adhesive to the foam, as a result the entire top sheet of the foam is lifted Counter Measures: • Coati Coating ng for top pap paper er to make iitt less a adhesiv dhesive e or d diffe ifferent rent top paper / top foil • Less ttin in or weaker stabili stabilizer zer to ma make ke the foam more open Limitation/Comment: • Sea Search rch for a n nonon-adhe adhesiv sive e foi foill nee needs ds to b be e done

 

Separation of Options: Optio ns: - more open foam

Top Layer

low adhe adhesion sion plast plastic ic foil - hea heatin ting g fr from om tthe he ttop op

 

2. Practical part Inhomogenous Inhomogen ous Flow on Conveyor Underrunning Underrunnin g/ Overrrolling Ove-Andre

Ove Andre Strand-Larsen    

Horizontal Big Top Splits Discontinous:

Box foaming

Continous:

Liquid laydown

Continous:

Maxfoam ® 

Continous:

Vertifoam

Failure: • Ho Hori rizon zonta tall big big top spl split its s (X) X

Reason: • These splits indica indicate te a mix of chemic chemical al a and nd me mechanica chanicall reasons. The foam is not creaming fast enough. Either the trough is too small and/or the angle of the first plate is to steep. Flow related (“under cutting”), justfall with fall plate machines Counter Measures: • Use more ore am amiine • Use bi bigger gger trough and/or change angle of th the e fir first st ffall all plate • Low Lower er o outpu utputt + low lower er co conve nveyor yor spee speed d • Incr Increa ease se o off frot froth h vi visco scosi sity ty Limitation/Comment:

 

Undercutting / Underrunning

(static liquid laydown)

 

Undercutting / (trough technology) (trough with two pipes)

Underrunning

 

Cavern Discontinous:

Box foaming

Continous:

Liquid laydown

Continous:

Maxfoam ® 

Continous:

Vertifoam

Failure: (X) X

• Ca Cave vern rn llik ike e spl split it iin n th the e ce cent nter er of ffoa oam m bl block ock Reason: • When tthe he fal falll plat plates es are ttoo oo ste steep, ep, tthe he ang angle le do does es not match the rise profile of the foam • Trough Trough height too llow ow,, wron wrong g output or tr trough ough s size ize • Ki Kind nd of un unde derr-ru runn nnin ing g • Occurs someti sometimes mes if fo formula rmulations tions are c changed hanged on-th on-the-fly e-fly Counter Measures: • Adjust the ang angles les of the fal falll plat plate e to th the e ri rise se prof profile ile o off the foam • Adj Adjustm ustment ent of ou outpu tput, t, tr trough ough si size ze and tr troug ough h heig height ht Limitation/Comment: -

 

Cavern

 

Cursive S-like Splits Discontinous:

Box foaming

Continous:

Liquid laydown

Continous:

Maxfoam ® 

Continous:

Vertifoam

Failure: (X) X

• Cu Curs rsiv ive e S lilike ke Spl Split its s(S ) Reason: • The There re iis s too m much uch a amin mine e in th the e for formul mulati ation on • “Ove “Overr-Ro Rollllin ing” g” of ma mate teri rial al • Fall Fall plat plate e to stee steep p Counter Measures: • Red Reduce uce am amine ine u unti ntill the sp split lits s disa disappe ppear ar.. • Re Reduc duce e fall fall plat plate e angl angle e Limitation/Comment:

 

2. Practical part Insufficient Homogenization in Troug Trough h

Ove-Andre Strand-Larsen    

1 Linear Split in Block Direction Discontinous:

Box foaming

Failure:

Continous:

Liquid laydown

• Lin Linear ear spl split it o on n to top p of the foa foam m bl block ock

Continous:

Maxfoam ® 

Continous:

Vertifoam

X

Reason: • The bl blend end in the tr trough ough is too lliquid iquid and/or the tr trough ough is too small. Valid Valid if trough is filled with two pipes. Material leaves the trough with a viscosity which is too low and flows down the conveyor. Counter Measures: • Use more ore am amiine • Re Reduc duce e fall fall plat plate e angl angle e • Cha Change nge to a pu pure re blo blowi wing ng c cata atalys lystt • Us Use e a bigg bigger er trou trough gh.. • Mor More e nucl nucleat eation ion air to iincr ncrease ease vis viscosi cosity ty Limitation/Comment:

Picture from: Arco Chemical Company, Flexible Polyurethane Slabstock Foam – An Overview of the Technology an

Troubleshooting Guide, by R. Schiffauer

 

2 Linear Splits in Block Direction Discontinous:

Box foaming

Failure:

Continous:

Liquid laydown

• 2 Lin Linear ear Spl Splits its on to top p of the ffoam oam blo block ck

Continous:

Maxfoam ® 

Continous:

Vertifoam

X

Reason: • The bl blend end in th the e trou trough gh is to too o liqu liquid id and and/or /or tthe he tr trough ough is too small. Valid Valid if trough is filled with three pipes. Material leaves the trough with a viscosity which is too low and flows dow down n the conveyor Counter Measures: • Use more ore am amiine • Re Reduc duce e fal falll pla plate te ang angle le • Cha Change nge to a pu pure re blo blowi wing ng c cata ataly lyst st • Us Use e a bigg bigger er trou trough gh • Mor More e nucl nucleati eation on a air ir to iincre ncrease ase v visco iscosit sity y Limitation/Comment:

 

2 Linear Splits in Block Direction

 

2. Practical Part Lacking Machine Synchronization

Ove-Andre Strand-Larsen    

Severe Side Splits

Discontinous:

Box foaming

Continous:

Liquid laydown

X

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Failure: • Seve Severe re Side Side Spli Splits ts Reason: • Differ Different ent s spee peeds ds of con convey veyor or and si side de wa wallll pape papers rs Counter Measures: • Syn Synchr chroni onize ze th the e spee speeds ds of tthe he con convey veyor or and tthe he side wall papers Limitation/Comment:

 

Top Layer Splits Discontinous:

Box foaming

Continous:

Liquid laydown

X

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Failure: • Seve Severe re top top lay layer er spl split its s Reason: • Dif Differ ferent ent sp speed eeds s of top pap paper versus rsus co conve yor an and d side wall papers. Speed of er topve paper is nveyor higher Counter Measures: • Synchr Synchroni onize ze tthe he sp speed eeds s of the top p pape aperr Limitation/Comment:

 

Top Region Splits with Inclination

 

Vertical Side Splits on one side of the block Discontinous: Continous:

Box foaming Liquid laydown

X

Continous:

Maxfoam ® 

X

Continous:

Vertifoam

Failure: • Vert ertical ical Sid Side e Spl Splits its on o one ne si side de o off the block Reason: • The side wa wallll pa paper pers s ar are e no nott ru runni nning ng simultaneously Counter Measures: • Che Check ck spee speed do off th the es side ide wal walll pa paper pers s and synchronize Limitation/Comment:

 

2. Practical part Pin Holes

Ove-Andre Strand-Larsen    

Pin Holes in General Discontinous:

Box foaming

X

Continous: Continous:

Liquid laydown Maxfoam ® 

X X

Continous:

Vertifoam

X

Failure: • Pin Pinhol holes es ar are e sma smallll rroun ound d hol holes es in tthe he fo foam am • The They y are d dist istrib ribute uted d in s smal maller ler or hi highe gherr amount throughout the whole block Reason: • Techn echnica icall issu issues es (see ffoll ollow owing ing sli slides) des) • Con Contam tamina inatio tion nw with ith o oils ils,, part particl icles es • Mayb Maybe e also entrap entrapped ped air ((but but typica typically lly o only nly at certai certain n places in the foam block) Counter Measures: • Che Check ck ra raw w mat materi erial al qu quali ality ty (p (part articl icles? es?)) • Che Check ck con contam tamina inatio tion n of the lline ines, s, the ta tanks nks an and d eve every ry equipment being used • Check careful carefully ly th the e distr distributi ibution on of the pi pin n holes over the bl block ock • Low Lower er ga gas s / air loa loadin ding, g, llowe owerr stir stirrer rer spe speed ed

Limitation/Comment: •

Toused so some mefor ext extent ent nor normal mal for low pre pressur ssure em machi achines nes as g gas/ as/air air is nucleation

 

Air from the Start Procedure Mix head contains air at the beginning:

Ideal situation

Pin hole causing situation (first 10 m with pin holes). Air „sticks“ to the stirrer pin once the stirrer is started.

before start

after start

 

Air from the Start Procedure Mix head contains air at the beginning, which may „stick“ to the stirrer Releasing gas bubbles at a later stage:

Special Ramp Special Ramp-up -up proc procedure edure:: 1. Start p po olyol pump a an nd flush the mix h he ead without starting the st stiirrer. F Fllush polyol (10 - 15 k kg g) in into a w wa aste bucket by usi sin ng a 3 way valve or directly into bucket for lquid laydown. 2. Afte fter a fe few w seco con nds sta start st stiirrer and all ot oth her streams and run production.

 

Air from „Dead“ Zones

In „dead zones“ material is not flowing And starts to foam releasing from time to time Gas bubbles and pieces of foam

Typ ypica icall pla places ces:: - Division o off pipes - Corners o off trough

Solution: - stre stream am-l -lin ine e des esig ign n (d (dif iffe fere rent nt ttro roug ugh h

or in inse sert rts, s, Y-s Y-sha hape ped d st stre ream am di divis visio ion) n)

 

Pin Holes in the Bottom Zone Discontinous:

Box foaming

Continous: Continous:

Liquid laydown Maxfoam

Continous:

Vertifoam

Failure: • Pin h hole oles s con concent centrat rated ed iin n the b bott ottom om zo zone ne (X) X

Reason: • The llip ip of the tr trough ough is too high (> 3 m mm) m) a above bove tthe he fa fallll plate. The out-coming foam is trapping air air.. The lip must be plain and clean. Check before with a stick the distance and the movability of the process liner liner.. Counter Measures: • The he heigh ightt of th the e tro trough ugh llip ip sho should uld b be e < 3 mm abo above ve th the e fall plate • Impro Improved ved p plastic lastic strip at the lip to avoid air trappi trapping ng Limitation/Comment: • Proble Problems ms b becomes ecomes more seriou serious s fo forr hi high gh vi viscous scous fr froth oth • Also som someti etimes mes for liquid liquid llayd aydown own C CO O2 processing  ®  (Novaflex ) (high viscosity of the froth)

 

Pin Hole Lines Discontinous:

Box foaming

Failure:

Continous:

Liquid laydown

• Pin H Hole oles s lin lines es th throu rougho ghout ut tthe he w whol hole e bloc block k

Continous:

Maxfoam

Continous:

Vertifoam

X

Reason: • Too m much uch air in P Poly olyol ol or TDI • Lea Leakage kage in the lilines nes clo close se to th the e trou trough gh an and/o d/orr mix he head ad • Lo Low w mix mix he head ad press pressur ure e • Bub Bubble bles s appe appear ar at th the e plac place e whe where re the pi pipes pes en enter ter tthe he trough. Therefore typically typically one or two lines of bubbles Counter Measures: • Lon Longer ger stor storage age of Pol Polyol yol and TD TDII • Solv Solvin ing g of th the e le leaka akage ge p pro robl blem em • Hi High gher er m mix ixin ing g hea head d pr press essur ure e Limitation/Comment:

Picture from: Arco Chemical Company, Flexible Polyurethane Slabstock Foam – An Overview of the Technology an Troubleshooting Guide, by R. Schiffauer

 

Pin Holes Low Pressure Machines Discontinous:

Box foaming

Failure:

Continous:

Liquid laydown

Continous:

Maxfoam

• Pin Pinhol holes es ar are e sma smallll rround ound hol holes es in tthe he fo foam. am. They are distributed in smaller or higher amount throughout the whole block

Continous:

Vertifoam

X

Reason: • Low pr pressure essure machin machines es n need eed ad additio ditional nal air iinjecte njected d in into to the polyol to achieve fine cells. When the foam block is showing pin holes this amount of additional air is too high or not properly mixed Counter Measures: • The a amou mount nt of inject injected ed ai airr has tto o be rredu educed. ced. • Incr Increa ease se mixe mixerr sp spee eed d • Pre Premix mix ai airr wit with h stabi stabiliz lizer er to ge gener nerate ate a frot froth h Limitation/Comment:

 

2. Practical part Diverse Issues

Ove-Andre Strand-Larsen    

„Bird Nest“ Discontinous:

Box foaming

Continous:

Liquid laydown

Continous:

Maxfoam

Continous:

Vertifoam

X

Failure: • Sma Smalle llerr cav cavern ern llike ike sp split lit in th the e low lower er pa part rt of the foam block (“bird nest”) Reason: • The a amou mount nt of the a amin mine e is to too o hi high gh an and/or d/or the blowing reaction is too accelerated acc elerated Counter Measures: • Use les less s am amine ine and and/or /or chan change ge to a less blowing amine Limitation/Comment:

 

„Chimneys“ Discontinous:

Box foaming

Continous:

Liquid laydown

X

Continous:

Maxfoam

X

Continous:

Vertifoam

Failure: • Chi Chimne mney y (d (deep eep cra crater ters so off th the eh heal ealth th bubbles) Reason: • Foa Foam m ha has s ver very y open cel cells. ls. B Blow low o off ff too too st stron rong g Counter Measures: • Incr Increas ease e stab stabili ilizer zer an and d stann stannous ous o octoa ctoate te in ste steps ps of 5% • Mak Make e sur sure e th that at tther here e is n no o le leakag akage e in a pip pipe e Limitation/Comment: • Hea Health lth bu bubbl bbles es ar are e nor normal mal,, but tthey hey sh shoul ould d not penetrate more than 3 cm into the foam

 

Top Splits Failure:

Discontinous:

Box foaming

Continous:

Liquid laydown

X

Continous:

Maxfoam

X

Continous:

Vertifoam

• Spl Splits its star startin ting g at the b bubb ubbles les wh when en fo foam am is still rising after the blow off Reason: • Ca Catal talys ysts ts a are re n not ot iin n ba bala lance nce

~~~ • ~ ~~~ •~ ~~~~ ~~~ •~ • ~~~ •~

Counter Measures: • Red Reducti uction on of sta stanno nnous us oct octoat oate e and inc increa rease se of am amine ine to bring the formulation back to a balanced reaction Limitation/Comment:

 

Top view on horizontal cut of block

Top Splits

 

Top Splits

 

2. Practical part Block Deformation During Storage

Ove-Andre Strand-Larsen    

Cold Flow Discontinous:

Box foaming

Continous: Continous:

Liquid laydown Maxfoam

Continous:

Vertifoam

Failure: • Def Deform ormati ation on o off the b bloc lock k dur during ing cur curing ing X X

• Typi ypical cal ffor or HR an and d vi viscoe scoelas lastic tic foa foam m Reason: • CrossCross-linkin linking gn not ot su suffic fficient ient to w withstan ithstand d gr gravity avity • Sl Slow ow coo cooliling ng rate rate of block block • Basi Basical cally ly a defo deforma rmatio tion n of the c cell ell sh shape: ape: mas mass s flow Counter Measures: • Increas Increase e cr cross-li oss-linking nking alrea already dy bef before ore m materi aterial al is e enteri ntering ng the storage area: mild cross-linkers (strong cross-linkers would cause a tight cell structure) • CrossCross-linke linkerr needs needs tto o be tailor tailored ed ffor or th the e giv given en pol polyol yol reactivity • Ad Adju just stab able le s sid ide e wa wall lls s Limitation/Comment:

• ORTEGOL ®  204 and/or KOSMOS ®  54 for HR foam

 

Cold Flow

 

Compression during Block Storage Failure: Discontinous:

Box foaming

X

Continous: Continous:

Liquid laydown Maxfoam

X X

Continous:

Vertifoam

• Cen Centra trall Com Compre pressio ssion n (of (often ten soft vis visco co gra grades) des) • Som Someti etimes mes just at th the e end o off lon long g foa foam m bl blocks ocks Reason: • Foam is in th the e hot stage ttoo oo soft to wit withstand hstand the gr gravity avity (chemical (chem ical visco foam! foam!)) • At lea least st ho horizont rizontal al or ma maybe ybe ev even en decl declining ining slope in the CLD curve • Gas ca can n onl only y esca escape pe at tthe he end o off the bl blocks ocks ((foam foam is relative tight) Counter Measures: • Bet Better ter p postost-cur curing ing ((for for e exam xample ple by KO KOSMO SMOS® S® 54) • Lo Low wer bu bun nh hei eigh ghtt • More cross-l cross-linkin inking g (mild (mild cross-l cross-linker inkers, s, higher index index)) • Fas aste terr co cool oliing • Addi Additi tion on of MDI

Limitation/Comment: • Mor More e cros cross-l s-lin inkin king g mak makes es foa foam m eve even n more ti tight ght • Bad for vi viscoe scoelas lastic tic pro proper pertie ties s  

Compression during Block Storage

 

Disclaimer

This trouble shooting presentation is intended for training purpose only. With respect to this Evonik disclaims any liability in connection with the use of services rendered and of the related information provided. It is the responsibility of the user to verify the accuracy of the service and the related information which can be used by the user at his own risk.