Additives for polyolefins: chemistry involved and innovative effects Mara Destro Intelligent packaging; session number7733
Outline of Presentation � Weatherability of HALS in LLDPE Film and Impact of PPA on the Performance of HALS � Oxygen Scavengers in Packaging Applications Mara Destro Session number 7733
Part I Weatherability of HALS in LLDPE Film and Impact of Polymer Processing Aids on the Performance of HALS Mara Destro Session number 7733
Polymer Processing Additives (PPA) � Eliminate Melt Fracture � Reduce Operating Pressure � Alleviate Die Build- Up � Reduction in Gel Formation � Typically Fluoroelastomers or Mixture with PEG Mara Destro Session number 7733
Hindered Amine Light Stabilizer (HALS) � Widely used for outdoor applications � Free radical scavengers � Effective in high surface area applications (Films) � However, HALS have been documented to have interactions with PPA � Is it possible to use HALS and PPA together without having negative interactions? � A continuation of the previous work � The HALS in this study: more according to current recommendations Mara Destro Session number 7733
Hindered Amines UV Stabilization via Free Radical Scavenging R· R R R [Oxidation] R* = - H N N N - CH 3 O R O · R* [H + ] R=O + ROH ROO· R X N + NOTE: An acidified hindered amine cannot easily enter into the free radical scavenging cycle R* H � N-H and N-R Hindered Amine Stabilizers (HALS) fit most needs regarding light stability, but can be alkaline (basic) � N-OR type HALS enter the UV stabilization cycle quickly, and are not alkaline, in comparison to N-H & N-R type HAS Mara Destro Session number 7733
Bring Out Your Magic DeCoder Rings • HALS-1 = Tinuvin 622 (N-R) • HALS-2 = Chimassorb 119 (N-CH 3 ) • HALS-3 = Chimassorb 944 (N-H) • HALS-4 = Tinuvin NOR 116 (N-OR) • HALS-5 = Chimassorb 2020 (N-H) • HALS-6 = Tinuvin 783: HALS -1 + HALS-3 (N-R + NH) • HALS-7 = Tinuvin 111: HALS -1 + HALS-2 (N-R +N-CH 3 ) • HALS-8 = Tinuvin NOR 371 (N-OR) • PPA = Dynamar FX-5920A Mara Destro Session number 7733
Structures of Various Hindered Amines R R N N HALS-2 N (CH 2 ) 6 N N N H N N R N N ] 2 - N N H N N N N H H R N CH 3 R = N n HALS-3 C 4 H 9 O R R O N O N H N NH N O HALS-1 R = R H HALS-4 n N N H H N N C 4 H 9 N N N C 4 H 9 N N N N N N N N N N N N N N N N N N N O O N n N N H H N Mara Destro H HALS-5 Session number 7733
Alkalinity of Various Hindered Amines Dominant pKa's of Various Hindered Amines (Piperidinyl Group) HALS-8 (N-OR) HALS-4 (N-OR) HALS-1 (N-R) HALS-2 (N-CH3) HALS-5 (N-H) HALS-3 (N-H) 0 2 4 6 8 10 pKa (as measured by titration of Conjugate Acid) Mara Destro Session number 7733
Experimental Procedures � Made 90 µ blown film samples using zn-LLDPE � Films contains HALS 1, 3, 6, 7, 8 @1500 and 3000ppm � One series with no PPA and the other with PPA � Xenon weathering per ASTM G155 to 8,000 hours � Mechanical properties � Color measurement after gas fade and oven aging Mara Destro Session number 7733
Performance of HALS Xenon Weathering of zn-LLDPE (w/ 1500 ppm HALS, No PPA) 125 none HA-3 (N-H) HA-1 (N-R) 100 HA-6 (NR+NH) HA-7 (NR+NCH3) % Retained Elongation HA-8 (N-OR) 75 50 25 0 0 2000 4000 6000 8000 Mara Destro Hours in Xenon Weatherometer Session number 7733
Influence of PPA on HALS Xenon Weathering of zn-LLDPE (w/ 1500 ppm HALS; 900 ppm PPA) 125 none HA-3 (N-H) HA-1 (N-R) 100 HA-6 (NR+NH) HA-7 (NR+NCH3) HA-8 (N-OR) % Retained Elongation 75 50 25 0 0 2000 4000 6000 8000 Mara Destro Hours in Xenon weatherometer Session number 7733
Gas Fade Discoloration with PPA Gas Fade Aging of zn-LLDPE: (w/1500 ppm HALS; 900 ppm PPA) 15 none HA-3 (N-H) HA-1 (N-R) HA-6 (NR+NH) HA-7 (NR+NCH3) 10 HA-8 (N-OR) YI Color 5 0 0 5 10 15 20 25 30 Mara Destro Day in Gas Fade Chamber at 60°C Session number 7733
Summary of Weatherometer Work • Ranking of HALS Performance in Weatherometer (no PPA) – Good: • HALS-1 (N-R) • HALS-3 (N-H) • HALS-7 (NR + N-CH 3 ) ≤ HALS-6 (NR + N-H) ≤ HALS-8 (N-OR) – Best • Ranking of HALS Performance with PPA: – Good: • HALS-1 (N-R) • HALS-7 (NR + N-CH 3 ) ≤ HALS-6 (NR + N-H) ≤ HALS-3 (N-H) • HALS-8 (N-OR) – Best Mara Destro Session number 7733
Conclusion � HMW NOR Hindered Amines and Hindered Amine blends are more effective in outdoor film applications than the individual HALS � Slight impact of the PPA on the effectiveness of the HALS � PPA have slight negative impact (15-20% reduction in physical properties): HALS-1, HALS-6, and HALS-7 � PPA has no impact: HALS-3 � PPA has slight positive impact: HALS-8 � It is possible to use HALS and PPA together without having negative interaction (selectively) Mara Destro Session number 7733
Part II Oxygen Scavenging Technologies for Food Packaging Applications • Review of Oxygen Scavenger Technology • Design Consideration in Packaging Applications • SPO 2 Oxygen Scavenger • Retort Example using EVOH/SPO 2 16 Mara Destro Session number 7733
Oxygen: The Spoiler • Residual oxygen within package & oxygen entering package throughout storage leads to product deterioration – Discoloration – Nutrient Loss – Off-Flavor – Texture Changes – Oxidative Rancidity 17 Mara Destro Session number 7733
Enhancing Barrier Properties • Traditional Means of Oxygen Exclusion – Metal & Glass Packaging – Barrier Plastic Packaging, Potentially Combine with • Gas Flushing • Vacuum Packaging • Still Enough Residual Oxygen to Cause Problems • Potential Solution: Scavenging Technologies in Combination with Barrier Packaging – Scavengers Chemically Bind Oxygen 18 Mara Destro Session number 7733
Oxygen Scavenging Chemistries • Metal Based Systems – Fe + 3/4 O 2 + 3/2 H 2 O ---- Fe(OH) 3 – Moisture activated • Oxidizable Polymers – Unsaturated hydrocarbon such as polybutadiene – Polyamides, MXD6 – Photoinitiator / UV activated • Low MWt Organic / Inorganic Compounds – Ascorbic acid derivatives – Sulfites – Reduced anthraquinone/ benzophenone derivatives 19 Mara Destro Session number 7733
Package Design Considerations • Determine Amount of Oxygen to Scavenge – Initially Present in Package • Headspace Volume • Dissolved Oxygen in Product – Oxygen Ingress over Time • Permeation Rate (Barrier) • Package Dimensions • Shelf-life (time) • Role of Scavenger – Head Space Oxygen Removal – Barrier Enhancement 20 Mara Destro Session number 7733
Package Design Considerations • Scavenger Characteristics – Oxygen Absorption Capacity – Scavenger Rate – Loading Limitations – Location of Scavenger within Package Structure • Any barrier layer between scavenger and food? 21 Mara Destro Session number 7733
SPO 2 Oxygen Absorber • SPO 2 : Scavenger Product for Oxygen (O 2 ) – Iron-based – Formulated oxygen scavenging systems – Polyethylene & polypropylene carrier resin – Incorporated in multilayer structure by coextrusion – Activated by water: RH ≥ 70% – Thermally stable up to 250°C Mara Destro Session number 7733
Effect of Relative Humidity on SPO 2 Absorption 100% SPO 2 Oxygen Absorption 80% Capacity 60% 40% 20% 0% 0 20 30 40 50 60 75 100 Relative Humidity (%) 23
Retort Applications: SPO 2 / EVOH • Retort: Steam sealed food @ 251-270F for up to 30 min. • PP/EVOH barrier widely used • EVOH Barrier: Very sensitive to humidity • “Retort Shock”—Reduction of EVOH barrier due to humidity increase in retort process • SPO 2 + EVOH: Complementary effects – Higher Moisture: SPO 2 most effective when EVOH loses barrier – Low Moisture: EVOH most effective when SPO 2 less effective Mara Destro Session number 7733
SPO 2 in Packaging Structure � Retorted Applications 25 Mara Destro Session number 7733
Barrier Performance Barrier behavior after retort 100% O 2 , 65%RH out - 100%RH in 0.0800 Packaging with no SPO 2 no retort - theoretically 0.0700 O2TR (cc/package.day.atm) Packaging with no SPO 2 after retort - theoretically 0.0600 Packaging with SPO 2 after retort - measured 0.0500 0.0400 0.0300 0.0200 0.0100 0.0000 0 10 20 30 40 50 60 70 Days 26 Mara Destro Session number 7733
Conclusion � Review of oxygen scavenger technologies � Oxygen scavenger can be a value tool in meeting some toughest packaging applications � Combination of passive barrier and oxygen scavenger can lead to improved barrier performance � SPO 2 / EVOH combination can lead to optimum synergic barrier performance in retort application Mara Destro Session number 7733
Acknowledgments � Ciba Specialty Chemicals – Joanni Turnier, Scott Allen, Marie-Raphael Morvillier, Joe Agocs, Jiong Yu, Peter Solera and Florian Stricker � Thank you for your attentions! Mara Destro Session number 7733
Backup Slides Mara Destro Session number 7733
Gas Fading O H O OH - H O H O NO 2 NO 2 O + H + N NO 2 O O slightly yellow strong yellow NO 2 -HONO O O O NO 2 -HONO NO 2 2RO . O H O -2ROH O OH vis-absorption106’000 [l*mol -1 cm -1 ] Mara Destro Session number 7733
Recommend
More recommend
