Introduction To Blown Film Thomas I Butler Blown

Introduction To Blown Film Thomas I. Butler Blown Film Technology, LLC tbutler@blownfilmtech. com 1 11/5/2020

Outline l l l l Polymer Blown Film Process Screw Die Bubble cooling Collapsing Winding 11/5/2020 2

Polymer MI vs. Fabrication Process Extrusion Coating LDPE Cast LLDPE/m-LLDPE Blown LLDPE/m-LLDPE 0 1 2 3 4 5 6 7 8 Melt Index Coextrusion and blends of LLDPE can extend MI ranges 11/5/2020 3

Polymer Crystallinity (Density) 0. 86 g/cc EPDM Non-polar (Co)Polymers EPR 0. 88 g/cc 0. 916 g/cc VLDPE 0. 940 g/cc LLDPE HDPE LDPE Elastomers Plastomer Metallocene-PE EPE Soft MODULUS Rigid EVA EMA Polar (Co)Polymers EBA EAA 11/5/2020 4

PE Polymer selection Blown Film Cast Film MI, dg/min 0. 05 – 6. 0 2. 0 - 10. 0 Density, g/cc 0. 88 – 0. 96 0. 86 – 0. 96 Very helpful Slight effect Broad is easier Narrow is OK LCB MWD 11/5/2020 5

Polymer Selection – Blown Film l LLDPE – MI Typically is 1. 0 to 0. 5 – Density depends on properties required l m-LLDPE – MI Typically is 1. 0 – Density depends on properties required l LDPE – MI Typically is 2. 0 to 0. 2 – Density ~ 0. 920 g/cc l HMW-HDPE – MI Typically is 0. 05 to 0. 08 – Density is 0. 940 to 0. 955 g/cc 11/5/2020 6

Blown Film Process 7 6 3 1 Feeding/Dosing 2 Extrusion 3 Electrical Control 4 Forming 5 Cooling 6 Guiding 7 Haul Off / Turner Bars 8 Winding 9 Automation 9 1 5 4 2 8 11/5/2020 7

Blown Film Processes Conventional Blown Film 11/5/2020 High Stalk Blown Film 8

Double Bubble Blown Film 11/5/2020 9

Blown Film Process Flattened Tube Vf , hf Equipment Screw design Die diameter (Ro) Die gap (ho) Air ring design Nip roll height (xnr) Process Control Output rate (M) Melt temp (Tm ) Bubble size (Rf ) FLH (xflh) Haul-off speed (Vf) Film thickness (hf) Nip rolls, xnr Rf DP Cooling Air z h(z) FLH, xflh r M, Tm 11/5/2020 10

Gravimetric Control Multi component blend ratio controlled by gravimetric blenders (3 to 6 components are common). Gravimetric Control Output rate is constant Screw Drive Speed 11/5/2020 11

Metering & Barrier Screws Metering Screw Barrier Screw 11/5/2020 12

Spiral Mandrel Die Inter Mandrel Die Gap, (ho) Die diameter, (Dd) Die Land Relaxation Zone Spirals Feed Ports 11/5/2020 Die Body 13

Coextrusion Concentric Die 11/5/2020 Three layer Blown Coextrusion Die - Reifenhauser 14

Pancake Coextrusion Die 11/5/2020 Ten layer Stacked Blown Film Die - Brampton 15

Die Specific Output Rate (DSO) • North America • M / (p x Dd) lb/hr/inch of die circumference • Europe • M / (Dd) • M = • Dd = 11/5/2020 kg/hr/mm die diameter Output rate, lb/hr (kg/hr) Die diameter, in (mm) 16

Blown Film Control Variables l Vf = M / (2 * p * Rf * hf * rs) > FLH l Vo = M / (2 * p * Ro * ho * rm) At die At constant film thickness (hf) M, Rf, Vf If: Then: M increases Vf increase and/or Rf decrease Rf increases Vf decrease and/or M increase Vf increases M increase and/or Rf decrease (Variables must also fall within range of equipment capability) 11/5/2020 17

Bubble Cooling l l l l 11/5/2020 Single lip Dual lip Internal Bubble Cooling (IBC) Stacked air rings Iris Chimney Chilled mandrels Water Bath 18

Frost Line Height Frost line should be parallel to the die with no spikes FLH T Air Hose Chiller Blower speed relates inversely to FLH p Manifold 11/5/2020 Blower Maintains cooling air temperature 19

Bubble Parameters BUR = ((2/p) LF) / Dd = Db / Dd = Blow Up Ratio DDR = Vf / Vo = (ho / (hf * BUR))* (rm/rs) = Drawdown Ratio T Tm T T T FLH = distance above die where expansion stops = Frost Line Height Internal Bubble Pressure, DP p Die Pressure Drop 11/5/2020 DSO = M/(p*Dd) = Die Specific Output 20

High Stalk Bubble – Neck Height FLH NLH T Air Hose Chiller Blower p Manifold 11/5/2020 21

Dual-Lip Air Ring 11/5/2020 Credit: Future design 22

Dual-lip Air Ring Bubble Ambient Air Supply Upper Lip Bernoulli Effect Cone Lower Lip Mounting Bracket 11/5/2020 Die 23

Internal Bubble Cooling (IBC) Bubble Air Ring Air Supply 11/5/2020 Die Body Air Outlet 24

Internal Bubble Cooling (IBC) Thickness gauge IBC cooling air exhaust 11/5/2020 IBC cooling air supply 25

Bubble Sizing IBC For High Stalk 11/5/2020 26

Layflat Control Layflat Width 11/5/2020 Bubble Diameter Sonic Sensors for IBC control 27

Bubble Collapsing l l l Wood slats Plastic covered slats Segmented rollers Rollers Air slide 11/5/2020 28

Oscillating Nip Roll Vertical 11/5/2020 Battenfeld Gloucester Horizontal W&H 29

Winders Center Surface Core Driven Roll 11/5/2020 30

Winder - Center 11/5/2020 31

Classical Process Variables BUR FLH DDR Die Size Melt Temp Output Air Ring Thickness Die Gap (None Are Independent Variables) 32 11/5/2020

FLH Interactions Velocity BUR Volume Temp Cooling Air Rel. Humidity Die Gap Thickness Melt Temp Output Air ring FLH 33 11/5/2020

Other Process Variables (>40) Process time Strain MD/CD Strain Rate MD/CD Residual Stress MD/CD U Cone, CLH, FLH, PLH, FLH Re die, CLH, FLH, PLH Nu , U C @ FLH, PLH, FZH Ftotal, Fhaul-off, Fhoop, Fnd CLH, PLH, FZH Strain Ratio Strain Rate Ratio Stress Ratio DP De MD/CD We MD/CD A, X’ f, q, b 34 11/5/2020

Common Film Properties l l l l 11/5/2020 Tensiles (MD/CD) – Yield – Ultimate Tensile – Elongation – Modulus Dart Impact Tear (MD/CD) Haze Gloss COF Block Shrink (MD/CD) Heat Seal Treatment Level Thickness Variation (MD/CD) WVTR OTR Gels 35

Polymer Property Models Non-Oriented Molecule Oriented Structure TD MD ND Intrinsic Property 11/5/2020 Mw, MWD, Xc , & CD Orientation & Crystallization Film Properties 36

Summary l l l Polymer selection is critical to achieving properties Equipment design may have limitations Fabrication conditions will influence properties 11/5/2020 37

Thank you Any Questions? 38 11/5/2020