Enhanced EVOH for Improved Orientability and Shrink

Transcription

1 Enhanced EVOH for Improved Orientability and Shrink PVdC Alternative for High Barrier Meat & Cheese Packaging Presented by: Gene Medlock Senior Research Engineer Kuraray America EVAL Business Unit

2 Introduction to EVOH Outline Barrier Shrink Bag Application Overview New EVOH Technology for PVdC Alternative Results of PVdC Benchmarking Evaluations Conclusions 2

3 Introduction to EVOH Higher Gas Barrier 24 M L F101/F171/F C H E105/E G176 mol% ethylene content Higher formability/orientability EVOH is a random copolymer of Ethylene and Vinyl-Alcohol (CH 2 -CH 2 ) m (CH 2 -CH) n OH 3

4 Oxygen Permeability Oxygen Transmission Rate of EVOH vs. Various Other Polymers OTR POLYMER (20 o C, 65%RH) EVOH 32 mol% EVOH 44 mol% PVDC copolymer (Extrusion Grade) O-PA O-PET HDPE CPP PC LDPE EVA Units : cm 3 20μm / m 2 day atm

5 EVOH Resin Applications Bottles Formed Flexible Cosmetics 5 Automotive PFT Under floor Heating Pipe Agri-chem Bottles

6 Barrier Shrink Bag Structures Development of alternative films and processing technology for barrier shrink bags is accelerating PO/PA/PO Very small % of bone-in meat structures PO/PVdC/PO Vast majority of boneless and bone-in meat pkg. & cheese pkg. PO/PA/EVOH/PA/PO PO/EVOH/PO Small % of boneless meat and cheese structures No commercial structures (boneless only) 6

7 Volume of Barrier Resin Used in Shrink Films 25,150 MT PVdC EVOH 7

8 Applications for EVOH in Shrink Films EU Current commercial shrink film structures are EVOH/PA 8

9 Unique Challenges in Double Bubble Film Process Performance targets include: Orientability High orientation ratio Low resistance to deformation Shrink properties High shrink ratio at low temp Oxygen Barrier To meet required shelf life Thermal stability Significantly better than PVdC Thermally induced dehydrochlorination at temperatures very near processing temperatures Brown color Extruder Coolant First bubble Die Cooling Device Preheater Heater Second bubble Annealing unit Winder 9

10 Meat Packaging Process Process: Vacuum packaging Shower tunnel Water quenching 1. Cut beef 5. Chilling (water bath) 2. Put beef in bag 3. Vacuum pack and seal Put in box 4. Shrink in hot water shower tunnel 80 o C 3 sec

11 Target for New Development Shrink ratio (% as Barrier and Shrink Property of Commercial Product Improved Shrink Target for Development: Improve shrink property Preserve barrier property OTR(cc/m PVDC Structure EVOH structure 11

12 New DBS (Double Bubble Shrink) Technology Development grade of DBS EVOH technology is XEP-1232 Enhanced 38 mol % EVOH using new technology Structure-properties of new DBS technology Thermal analysis Evaluation of viscoelastic properties Biaxial orientation tests Monolayer films Constant and increasing strain rate tests Shrink performance Oxygen barrier properties Evaluations were conducted to compare XEP-1232 vs. 1. Conventional 38 mol% EVOH and PVdC (polyvinylidene chloride)

13 Thermal Analysis DBS EVOH Technology reduces T m and T c by ~25 C T g reduced by ~10 C DBS EVOH Conventional 38 mol% EVOH 13

14 Viscoelastic Properties 1.0E+10 E' (Pa) 1.0E E+08 Conv. 38 mol% EVOH DBS EVOH 1.0E+07 Improved viscoelasticity Temperature ( o C) 14

15 15 Biaxial Orientation Stretch Evaluation Instrumented Simultaneous Biaxial Orientation Orientation Ratios (equi-biaxial): 2X2, 3X3, 4X4 and max (>5X5) Strain rate: 5 meter/min Temperatures: 80 o C, 90 o C and 100 o C n = 3 EVOH materials Conventional 38 mol% grade EVOH DBS EVOH grade Sample specimens produced via cast film extrusion PVdC material Copolymer of vinylidene chloride and methyl acrylate Sample specimens produced via 2-step compression molding process using raw PVdC powder Samples conditioned just prior to testing to reverse secondary crystallization Conditioning method: Re-heat films in hot press at 175 o C for 45 seconds, followed immediately by quick quenching in cold water

16 16 Bi-Axial Stretch Test

17 17 Key Biaxial Orientation Stretch Test Result

18 Bi-Axial Orientation Inflation Evaluation Instrumented biaxial orientation by inflation Orientation ratio: up to 4X4 (approximation) Strain rate (variable): up to 300 %/s Temperatures: 80 o C, 90 o C n = 3 EVOH materials Conventional 38 mol% grade EVOH DBS EVOH grade Sample specimens produced via cast film extrusion PVdC material Copolymer of vinylidene chloride and methyl acrylate Sample specimens produced via 2-step compression molding process using raw PVdC powder Samples conditioned just prior to testing to reverse secondary crystallization Conditioning method: Re-heat films in hot press at 175 o C for 45 seconds, followed immediately by quick quenching in cold water 18

19 Bi-Axial Inflation Test Stress Engineering Services (SES) Cincinnati, OH Bi-axial inflation test for acquiring stress vs. strain and strain-at-failure data for plastic films over a range of strain rates 1. Flat specimen is clamped to test structure and pressurized 2. As specimen is inflated, the height of bubble is measured to calculate strain 3. Stress is calculated in the material using measured pressure in bubble and formula for thin walled pressure vessel 4. Assumption is spherical deformation 5. Air pressure (strain rate) adjusted by pressure regulator controlled by voltage proportional controller 19 Laser to Measure Inflated Specimen Height

20 Bi-Axial Inflation Test Samples are heated by elements on the underside of fixture Thermocouple and controller control the heat of plate Specimen is allowed time to reach specified test temperature 20

21 21 Key Biaxial Inflation Test Result

22 Shrink Testing Analysis of oriented monolayer specimens from bi-ax stretch evaluation Oriented film shrinkage measured at 80 C and 90 C Shrink bath time = 3 seconds Specimen size: 4 square for 4X4 (cut from center of oriented film) Made pre-shrink gauge profile Measure dimension of post shrink specimens n = 4 22

23 DBS EVOH shrink Key Shrink Result Samples from 80 o C - 4x4 Orientation 72% at 80 o C shrink temp 83% at 90 o C shrink temp PVdC yielded no shrink at 80 or 90 o C Possibly due to secondary crystallization in stretch test PO/PVdC double bubble film yields shrink 65 85% 23

24 Oxygen Barrier Properties OTR (cm 3. 20μm/m 2. day) at 20 C 24

25 Conclusions New DBS EVOH offers significantly improved orientability New DBS EVOH also provides high shrink-ability at low temperatures, comparable to PVdC DBS EVOH yields good preservation of barrier properties despite reduction in crystallinity DBS technology may be utilized in other barrier applications where improved formability or orientability is required 25

26 Kuraray Co., LTD. Hiroyuki Shindome Takeyuki Igarashi Shinji Tai Acknowledgements Stress Engineering Services Diana Brown Ray Newman IMI CNRC Nathalie Chapleau Michel Carmel 26

27 Thank you PRESENTED BY Gene Medlock Senior Research Engineer Kuraray America EVAL Business Unit 27 Please remember to turn in your evaluation sheet...