Introduction To Blown Film Thomas I. Butler Blown Film Technology, LLC tbutler@blownfilmtech.com 11/13/2018

Outline Polymer Blown Film Process Screw Die Bubble cooling Collapsing Winding 11/13/2018

Polymer MI vs. Fabrication Process Extrusion Coating LDPE Cast LDPE Cast LLDPE/m-LLDPE Blown LDPE Blown LLDPE/m-LLDPE Melt Index 8 7 6 5 4 3 2 1 Coextrusion and blends of LLDPE can extend MI ranges 11/13/2018

Polymer Crystallinity (Density) 0.86 g/cc 0.88 g/cc 0.916 g/cc 0.940 g/cc EPDM VLDPE LLDPE HDPE EPR Non-polar (Co)Polymers LDPE Elastomers Plastomer Metallocene-PE EPE Soft MODULUS Rigid EVA EMA Polar (Co)Polymers EBA EAA 11/13/2018

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 LCB Very helpful Slight effect MWD Broad is easier Narrow is OK 11/13/2018

Polymer Selection – Blown Film LLDPE MI Typically is 1.0 to 0.5 Density depends on properties required m-LLDPE MI Typically is 1.0 LDPE MI Typically is 2.0 to 0.2 Density ~ 0.920 g/cc HMW-HDPE MI Typically is 0.05 to 0.08 Density is 0.940 to 0.955 g/cc 11/13/2018

Blown Film Process 1 Feeding/Dosing 2 Extrusion 3 Electrical Control 7 1 Feeding/Dosing 2 Extrusion 3 Electrical Control 4 Forming 5 Cooling 6 Guiding 7 Haul Off / Turner Bars 8 Winding 9 Automation 6 3 9 1 4 2 5 8 11/13/2018

Blown Film Processes Conventional Blown Film High Stalk Blown Film 11/13/2018

Double Bubble Blown Film 11/13/2018

Blown Film Process Equipment Screw design Die diameter (Ro) Flattened Tube DP z r FLH, xflh Cooling Air h(z) Rf Nip rolls, xnr M, Tm 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) 11/13/2018

Gravimetric Control Multi component blend ratio controlled by gravimetric blenders (3 to 6 components are common). Gravimetric Control Screw Drive Speed Output rate is constant 11/13/2018

Metering & Barrier Screws Metering Screw Barrier Screw 11/13/2018

Spiral Mandrel Die Inter Mandrel Die Gap, (ho) Die diameter, (Dd) Die Body Die Land Relaxation Zone Die Gap, (ho) Inter Mandrel Spirals Feed Ports Die diameter, (Dd) 11/13/2018

Coextrusion Concentric Die Three layer Blown Coextrusion Die - Reifenhauser 11/13/2018

Pancake Coextrusion Die Ten layer Stacked Blown Film Die - Brampton 11/13/2018

Die Specific Output Rate (DSO) North America M / (p x Dd) lb/hr/inch of die circumference Europe M / (Dd) kg/hr/mm die diameter M = Output rate, lb/hr (kg/hr) Dd = Die diameter, in (mm) 11/13/2018

Blown Film Control Variables Vf = M / (2 * p * Rf * hf * rs) > FLH 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) 11/13/2018

Bubble Cooling Single lip Dual lip Internal Bubble Cooling (IBC) Stacked air rings Iris Chimney Chilled mandrels Water Bath 11/13/2018

Frost Line Height FLH Air Chiller Hose Manifold Blower Frost line should be parallel to the die with no spikes FLH T Air Hose Blower speed relates inversely to FLH Chiller p Manifold Blower 11/13/2018 Maintains cooling air temperature

Bubble Parameters BUR = ((2/p) LF) / Dd = Db / Dd = Blow Up Ratio DDR = Vf / Vo = (ho / (hf * BUR))* (rm/rs) = Drawdown Ratio FLH = distance above die where expansion stops = Frost Line Height DSO = M/(p*Dd) = Die Specific Output T T T Tm T T Internal Bubble Pressure, DP p Die Pressure Drop 11/13/2018

High Stalk Bubble – Neck Height FLH NLH T Air Hose Chiller Blower p Manifold 11/13/2018

Dual-Lip Air Ring Credit: Future design 11/13/2018

Dual-lip Air Ring Bubble Ambient Air Upper Lip Air Supply Bernoulli Effect Cone Lower Lip Mounting Bracket Die 11/13/2018

Internal Bubble Cooling (IBC) Air Ring Die Body Air Supply Air Outlet 11/13/2018

Internal Bubble Cooling (IBC) Thickness gauge IBC cooling air supply IBC cooling air exhaust 11/13/2018

Bubble Sizing IBC For High Stalk 11/13/2018

Layflat Control Layflat Bubble Diameter Width Sonic Sensors for IBC control 11/13/2018

Bubble Collapsing Wood slats Plastic covered slats Segmented rollers Air slide 11/13/2018

Oscillating Nip Roll Vertical Horizontal W & H Battenfeld Gloucester 11/13/2018

Winders Center Surface Driven Roll Core 11/13/2018

Winder - Center 11/13/2018

Classical Process Variables BUR FLH DDR Die Size Melt Temp Output Air Ring Thickness Die Gap (None Are Independent Variables) 11/13/2018

FLH Interactions FLH Velocity Volume Temp Rel. Humidity BUR Cooling Air Die Gap Thickness Melt Temp Output Air ring FLH 11/13/2018

Other Process Variables (>40) Process time CLH, PLH, FZH Strain MD/CD Strain Ratio Strain Rate MD/CD Strain Rate Ratio Residual Stress MD/CD Stress Ratio U Cone, CLH, FLH, PLH, FLH DP Re die, CLH, FLH, PLH De MD/CD Nu , U We MD/CD C @ FLH, PLH, FZH A, X’ Ftotal, Fhaul-off, Fhoop, Fnd f, q, b 11/13/2018

Common Film Properties 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 11/13/2018

Polymer Property Models Non-Oriented Molecule Orientation & Crystallization Intrinsic Property Oriented Structure Mw, MWD, Xc , & CD Film Properties MD ND TD 11/13/2018

Summary Polymer selection is critical to achieving properties Equipment design may have limitations Fabrication conditions will influence properties 11/13/2018

Thank you Any Questions? 11/13/2018