Extrusion guidelines
Polyamide extrusionProcessing guidelinesTed Brink
Page nr.some simple guidelinesfor nylon extrusion
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Moisture POLYAMIDESarehygroscopic
Page nr.How to deal with moisturereliable resin manufacturers
supply nylon dry and ready-to-useavoid moisture absorptionuse
packaging size according to consumptionshield hopper from
atmospheremaximum allowable moisture content 0.1 %
Page nr.Too high moisturetoo high moisture content results
in:bubbles/foaming of the meltholes in the filmbubble
collapseshydrolytic breakdown
Page nr.Screws for polyamide extrusionGeneral Purpose screws can
be used, provided:the barrel is not grooved (unless .....)the
heating capacity is sufficientthe compression ratio is < 4.0the
L/D ratio is > 24barrier screws suitable
Page nr.Mixing or dispersing elementsmixing sections on standard
3-zone screws may be neededdispersing antiblock agentpigmentsnot
needed for standard additives mixing elements:pineapple
(distributive mixing)pin(distributive mixing)Maddock (dispersive
mixing)
Page nr.Screen packFunction:build-up pressurefiltration
Page nr.Extruder output PA6 extrusionsingle screw3-zoneTcil 250
C
Page nr.Thermal properties of PA6
processing range
crystal growth
melting point
glass transition temperaturetemperature [C]
Page nr.Communicate with the machinelisten to what the machine
is telling youwatch energy demand of band heatersshows where energy
is neededshows where no energy is neededavoid adiabatic
extrusionthe machine is in control, not you!Tpol will show large
variations
Page nr.Temperature settingstoo low settings may result in too
high polymer temperaturenylons with higher crystallinity require
different approach
Page nr.Melt stabilitypolyamide is a condensation
polymerconsequence for extrusion:when dry: polymerization
occurswhen wet: depolymerization occursreactivity depends
on:moisture contentresidence timetemperatureend groups
Page nr.MiscelleneousBlown film:BUR 1:1 1:3lay flat when film is
stil warm to prevent wrinklesGeneral:die gap 1 1.2 mmCast
film:Chill roll temperature:20 40 C for optimum thermoforming
behavior80 130 C for optimum dimensional stabilitychill roll as
close to the die to avoid neck-in
Page nr.Film post treatmentCorona treatmentPlasma treatmentFlame
surface treatmentPurpose of these treatments:increase surface
energy so that inks wet-out improve adhesion during
laminationHowever, polyamide has intrinsically good printing and
lamination performanceand thus no real need for Corona
treatment
untreated filmtreated film
Page nr.Polyamide film propertiesfilms are (near to)
isotropicfilms are transparenthigh puncture resistance
Page nr.Influence of moisture on film propertieswhen dry:very
high oxygen barrierhigh moduluswhen conditionedhigh oxygen
barrierincreased flexibilitypostcrystallization possibledimensional
fluctuations
Page nr.Coextrusionpolyamide mostly used in multilayer
structurespolyamide function:mechanical protectionbarrier
propertiestie resin required for adhesion to nonpolar polymers like
PE and PPcoectruded polymers should rheologically match
Page nr.ApplicationsFood packagingcheesemeat fish
Non foodagricultural filmsmedical filmsrelease films for smc
Page nr.Contact
Ted BrinkEmail: [email protected]:
www.extrusionist.comTel.: +31 651109899More information
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