Download - Polyamide extrusion
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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