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MINERAL REINFORCED COMPOUNDS FORCOMPOSTABLE FILM EXTRUSIONSPE FlexPack ConferenceHouston, TXMarch 1, 2011
Frank A. RuizPresident, Plastimin LLCResearch Consultant, Heritage Plastics, Inc.P.O. Box 271769Flower Mound, TX [email protected]
Development of Film Extrusion Compounds for Packaging Applications
Identify cost requirements
Define critical end-product parameters Mechanical, Optical, Barrier
Evaluate processing requirements vis-à-vis current equipment
Compostable Product Development Impetus
Volume of Solid Waste Generated in U.S. Increasing 70 MM Tons in 1960 229 MM Tons in 2001
Number of Landfills in U.S. is decreasing 7924 in 1988 1858 in 2001 (-77% in 13 years, mostly smaller
operations) Virtually impossible to site new landfills
(NIMBY) Incineration resisted in many areas Recycling rates have been difficult to increase
An Enormous Potential Resource
Limited Composting Done Today
Woodhue Compost Testing
Final Screening at Woodhue
WHAT IS COMPOSTING?A process using thermophilic (heat-loving) bacteria that are naturally-occurring in organic waste
Bacteria grow and consume raw materials under the proper conditions:
High heat (136 – 158 deg F)MoistureOxygenOrganic raw materials
High heat “sterilizes” waste by killing pathogenic bacteria (i.e., the ones that make us sick)
COMPOSTING: WHAT & WHYCompost microorganisms “eat” just about anything organic:
•Yard Waste•Wood trimmings•Food Waste•Carrion/Road Kill•Paper & Waxed (not PE-coated) Linerboard
Compost end product is a valuable soil nutrient and augmentationNew composting facilities opening in US
Encouraged by EPA as a method of landfill diversionRequires less physical “footprint” than landfillNew operation in Brooklyn, NY!
Product Development Impetus
First Major Compostable Film Opportunity:
Develop compostable bags and can liners for:
Organic Waste diversion from grocery stores & restaurants
Yard Waste collection by municipal & private waste haulers destined for composting
Product Development Requirements
Product MUST meet ASTM D 6400: Specification for Compostable Plastics
ASTM D 6400 requires: 90% mineralization to H2O & CO2 in 180
days Fragmentation: 90% to < 2.0 mm Ecologically non-toxic when measured
using ASTM D 6002 or OECD Guideline 208
PE “oxo-degradable” bags after 60 days
Development of Compounds for Trash Bag & Can Liners Commodity Market; Cost Critical;
competition is cheap labor Need high puncture, tear, &
tensile strength combined with high ductility
Clarity not critical (translucent) Not require drying Process on current equipment
Same extruder screw, die, air ring Able to print, heat seal, slit…
Commercially-Available Compostable Resins in N.A. Aromatic/Aliphatic Co-polyester
Easy to extrude, no need to dry Film extremely elastic
Plasticized Starch Blend Easy to extrude, moisture level critical, very
rapid biodegradation Poly-Lactic Acid
VERY moisture sensitive Not suitable by itself for film extrusion &
conversion PHA
Film extrusion difficult without modification
Aliphatic-Aromatic Co-Polyester(A-A copolyester)
Readily available in US from BASF as Ecoflex™ Suppliers of similar grades in Asia not
exporting to N.A.
Does not require drying prior to extrusion
BASF dedicated to the growth of the Market Technical and Marketing Support
Plasticized Starch Blends
Available in US from Novamont Partially based on renewable
resources Require a specific moisture level for
extrusion Novamont helped pioneer and is
dedicated to the growth of the Market
PolyLactic Acid (PLA)
Readily available in US from NatureWorks LLC
Based on renewable resources Moisture Sensitive NatureWorks very dedicated to the
growth of the market Technical and Marketing Support
PolyHydroxy Alkanoates (PHA, PHB)
Available commercially from Telles & Tianen Biologic
Based on renewable resources Telles has started a 50KT/yr. plant in
Clinton, IA Dedicated to the growth of the Market Technical and Marketing Support
* Telles is a J.V. between Metabolix and A.D.M.
Processing Characteristics of Compostable Polymers
Drying of PLA required before extrusion to prevent breakdown to lactic acid
Most co-polyesters also must be dried (except BASF Ecoflex™)
PHA does not require drying except for HT extrusion
Starch blends require proper moisture level for extrusion
Physical Properties of Compostable Polymers
Physical properties Co-polyesters very elastic PLA very rigid PHA rigid to flexible; crystalline surface Modified starch a range of properties Blends offer a range of properties
Temperature Resistance PLA heat resistance – new grades available Co-polyesters poor heat resistance PHA higher heat resistance (MP = 180° C).
COMPOSTABLE PACKAGINGAPPLICATION DEVELOPMENT PROCESS
Market is growing rapidly (50%/yr) as more institutions initiate organic waste diversion (airports, malls, stadiums, office buildings, golf courses)
Base product on compostable polymers Blend polymers and mineral(s) to
achieve desired end-use properties Utilize low levels of additives if
necessary to improve processing without sacrificing D 6400 Certification
Product Development Strategy
Formulate polymer blends to achieve intermediate properties, processability
Utilize Heritage Plastics polymer mineral reinforcement technology to modify co-polyester film properties Increase Stiffness Improve Productivity, Convertability Improve Bag Aesthetics Reduce Cost
Any additives must not interfere with composting process
All ingredients must have no potential for bioaccumulation or plant uptake
Product Development Synergy
Test compounded blends at Heritage Bag Company Utilize film extrusion & conversion
expertise Support desire to enter market
Adapt rate of degradation Rapid for organic waste diversion Slower for fresh-cut grass and yard
trimmings Result: Compounded blends of
Biodegradable polymers & either talc or calcium carbonate
Compostable Product DevelopmentBench-Scale Compost Testing – Atlanta, GA
Compostable Product DevelopmentBench-Scale Compost Testing
Development of Compounds for Compostable Film Extrusion
Work to date has yielded two commercial compostable film extrusion grades:
Compound A: A-A-copolyester, poly-lactic acid, talc (Biotuf™ 970)
Compound B: A-A-copolyester, poly-hydroxyalkanoate, & calcium carbonate (Biotuf™ 978)
Development of Compounds for Compostable Film Extrusion
Compound A: A-A-copolyester base poly-lactic acid added to increase
stiffness talc added to increase stiffness, bubble
stability, film antiblocking, reduce cost 2500ppm slip
Development of Compounds for Compostable Film Extrusion
Compound B: A-A-copolyester base poly-hydroxyalkanoate for stiffness,
mineralization rate increase, bio-based content
calcium carbonate to increase bubble stability, film antiblocking, reduce cost
Developed in partnership with Telles/Metabolix
Extrusion of Compostable Film Compounds
Melt temperatures 160 – 180 ° C (320 – 360° F) Cooler than LLDPE or HMW-HDPE, similar to LDPE PHA begins to thermally decompose > 180° C
Minimize shear and residence time (PHA) Resins & Compounds are Polar:
Effective “purge” agents Higher tendency to stick to metal (i.e. screw root) Conventional PE slip agents less effective
Purge & start up line with 2 – 4 MI LDPE to minimize scrap
Processing of Compostable Resins
Extruder Type * 65mm GF 65mm GF 65mm GF
Extruder RPM 70 70 70
Die Size, mm 225 225 225
Die Gap, mm 1.5 1.5 1.5
Melt Temp °C (°F)
216 (420) 160 (320) 170 (340)
Output Rate, kg/ hr. (lb.hr)
218 (480) 180 (396) 170 (374)
Blown Film Extrusionof Compostable Compounds
Extruder = 65 mm grooved-feed, 24/1 L/D GP dual purpose screw (LLD & HMW-
HDPE) Die = 225 mm Die gap = 1.5 mm Compound A extensional rheology
(bubble) similar to LDPE Compound B extensional rheology
(bubble) similar to LLDPE (run “In the Pocket”)
Extrusion of Compostable ResinsCompound A B
Extruder Profile:
Barrel Profile, °F 280/290/300/300 340/320/300/300
Adapter/Die, °F 320/320 340/340
Process Conditions:
Extruder RPM 70 70
Head Pressure, psi 3400 3200
Melt Temp °C (°F) 160 (320) 170 (340)
Output Rate, kg/ hr. (lb.hr) 180 (396) 170 (374)
Co-PET/PLA/TalcCompostable Compound Extrusion
Co-PET/PHA/CaCO3Compostable Compound Extrusion
Properties of Compostable Films
Compound Type Compound A Compound B C-6 LLDPE
Film Thickness, mils
1.2 1.2 1.2
Dart Impact, g 350 240 280
Elmendorf Tear, g MD 320 250 280
TD 180 700 480
Properties of Compostable Films
Compound Type Compound A Compound B C-6 LLDPE
Film Thickness, mils
1.2 1.2 1.2
Tensile Strength @ yield, psi
MD 2000 No defined yield
1500
TD 2100 1700 1600
Tensile Strength @ break, psi,
MD 4500 4000 5500
TD 3800 3280 4500
Compostable Product Certification
Films biodegrade >90% in <180 days Films satisfy the requirements of ASTM
D6400–04: Standard Specification for Compostable Plastics: Compound A at 3 mils and below Compound B at 14 mils and below
Certified by BPI
Compound B @ 0.25 mm Hot Composting Test at OWS
Jan. 08, 2010 XS
Compound B @ 0.35 mm Hot Composting Test at OWS
Jan. 08, 2010 XS
Advantages of Compostable Bags and Liners
Certification by Biodegradable Products Institute required for Composter evaluation (not acceptance!)
Allows Pre- and post-consumer food waste diversion with minimal health hazard and odor
Provide tear and puncture resistance similar to PE products in use
Lifting strength and load capacity necessary for wet refuse
• Environmental• Higher renewable materials content • Faster Composting (More rapid mineralization)
• Reduce resistance to film at compost facilities• (Not for fresh cut grass)
• Greater D6400 maximum thickness Rating 0.35mm• Potential Bio-Energy Production - Anaerobic Digestion
with sufficient PHA content
•Logistical• Domestically-sourced material (Telles)• Non-petroleum Feedstock ($ stability)
Characteristics of PHA containing compostable compound
Characteristics of PHA containing compostable compound
Film Properties Commercial Film Processing Rates Excellent Dart and Tear strength MD strain hardening yields high load capacity Bag Shelf Life approximately 12 mos.
Summary Compounded blends of available compostable
polymers yields compostable film formulations Mineral addition improves product performance and
lowers cost Proper ratios of resins and minerals key to
obtaining desired processing characteristics and end product properties Different compounds may require equipment
modifications to equipment configuration and/or process conditions
Look to supplier for guidance More commercial composting = more
opportunity for compostable packaging Will require labeling & consumer education