Additives for polyolefins: chemistry involved and innovative effects - - PowerPoint PPT Presentation

Additives for polyolefins: chemistry involved and innovative effects

Mara Destro Intelligent packaging; session number7733

Mara Destro Session number 7733

Outline of Presentation

Weatherability of HALS in LLDPE Film

and Impact of PPA on the Performance

• f 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

• n 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

R* H ROO· R=O + ROH R· [Oxidation] R N O R N O· R R N R* [H+] R N+

X

NOTE: An acidified hindered amine cannot easily enter into the free radical scavenging cycle R* = - H

• CH3

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

Hindered Amines UV Stabilization via Free Radical Scavenging

Mara Destro Session number 7733

Bring Out Your Magic DeCoder Rings

• HALS-1 = Tinuvin 622

(N-R)

• HALS-2 = Chimassorb 119

(N-CH3)

• 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-CH3)
• HALS-8 = Tinuvin NOR 371

(N-OR)

• PPA = Dynamar FX-5920A

Mara Destro Session number 7733

Structures of Various Hindered Amines

N N N N N N N N H H H (CH2)6 n N N N N N N N N R R H R R ]2- N N CH3 C4H9 R =

N O O O O

n

HALS-3 HALS-5 HALS-4 HALS-1 HALS-2

N N N N N N N O O R = C4H9 C4H9 N H N NH N R R H R

N N N N N N H N N N N N H N N H N N H N N N N N H N N N n

Mara Destro Session number 7733

2 4 6 8 10 pKa (as measured by titration of Conjugate Acid) HALS-3 (N-H) HALS-5 (N-H) HALS-2 (N-CH3) HALS-1 (N-R) HALS-4 (N-OR) HALS-8 (N-OR) Dominant pKa's of Various Hindered Amines (Piperidinyl Group)

Alkalinity of Various Hindered Amines

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) 25 50 75 100 125 2000 4000 6000 8000 Hours in Xenon Weatherometer % Retained Elongation none HA-3 (N-H) HA-1 (N-R) HA-6 (NR+NH) HA-7 (NR+NCH3) HA-8 (N-OR)

Mara Destro Session number 7733

Influence of PPA on HALS

Xenon Weathering of zn-LLDPE (w/ 1500 ppm HALS; 900 ppm PPA) 25 50 75 100 125 2000 4000 6000 8000

Hours in Xenon weatherometer % Retained Elongation

none HA-3 (N-H) HA-1 (N-R) HA-6 (NR+NH) HA-7 (NR+NCH3) HA-8 (N-OR)

Mara Destro Session number 7733

Gas Fade Discoloration with PPA

Gas Fade Aging of zn-LLDPE: (w/1500 ppm HALS; 900 ppm PPA) 5 10 15 5 10 15 20 25 30 Day in Gas Fade Chamber at 60°C YI Color none HA-3 (N-H) HA-1 (N-R) HA-6 (NR+NH) HA-7 (NR+NCH3) HA-8 (N-OR)

Mara Destro 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-CH3) ≤ 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-CH3) ≤ 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

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Part II Oxygen Scavenging Technologies for Food Packaging Applications

• Review of Oxygen Scavenger Technology
• Design Consideration in Packaging Applications
• SPO2 Oxygen Scavenger
• Retort Example using EVOH/SPO2

Mara Destro Session number 7733

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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

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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

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Oxygen Scavenging Chemistries

• Metal Based Systems

– Fe + 3/4 O2 + 3/2 H2O ---- 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

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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

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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?

Mara Destro Session number 7733

SPO2 Oxygen Absorber

• SPO2: Scavenger Product for Oxygen (O2)

– 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

23

Effect of Relative Humidity on SPO2 Absorption

0% 20% 40% 60% 80% 100% 20 30 40 50 60 75 100 Relative Humidity (%) SPO2 Oxygen Absorption Capacity

Mara Destro Session number 7733

Retort Applications: SPO2 / 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

• SPO2 + EVOH: Complementary effects

– Higher Moisture: SPO2 most effective when EVOH loses barrier – Low Moisture: EVOH most effective when SPO2 less effective

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SPO2 in Packaging Structure

Retorted Applications

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Barrier Performance

Barrier behavior after retort 100% O2, 65%RH out - 100%RH in 0.0000 0.0100 0.0200 0.0300 0.0400 0.0500 0.0600 0.0700 0.0800 10 20 30 40 50 60 70 Days O2TR (cc/package.day.atm)

Packaging with no SPO2 no retort - theoretically Packaging with SPO2 after retort - measured Packaging with no SPO2 after retort - theoretically

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

SPO2 / EVOH combination can lead to

• ptimum 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 H O NO2 NO2 NO2 O

• HONO

O O H OH

• HONO

NO2 O O O H NO2 O NO2 2RO.

• 2ROH

O N

+

O O OH- H+ slightly yellow strong yellow

vis-absorption106’000 [l*mol-1cm-1]

Mara Destro Session number 7733

Typical Structure of Polymer Processing Aid

F F H H CF3 F F F

n m

C C C C

δ− δ− δ− δ− δ+ δ+

Mara Destro Session number 7733

Summary of Previous Work

• Ranking of HALS Performance in Weatherometer

– Good:

• HALS-1 (N-R)
• HALS-2 (N-CH3)
• HALS-3 (N-H) ≤ HALS-5 (N-H) ≤ HALS-4 (N-OR)

– Best

• Ranking of Interaction of HALS with PPA:

– Most interaction:

• HALS-3 (N-H)
• HALS-5 (N-H) ≤ HALS-4 (N-OR) ≤ HALS-2 (N-CH3)
• HALS-1 (N-R)

– Least Interaction

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Oxygen Scavenger Technology

• Under Development for 30+ years
• Recent Trends Contributing to Interest in Oxygen

Scavenger Technology

– Convenience Packaging – Increased Plastic Usage – Shelf Stable – No Need for Refrigeration – Demand for Improved Quality

• Taste
• Texture
• Appearance

– Tailoring Package Environment for Product Needs

Mara Destro Session number 7733

Oxygen Scavenging Sachets

• Strengths

– Established Market Presence – Large Absorption Capacity – Baseline for Price/Performance Evaluations – Many Options

• Challenges

– Processing Speed

• Reduced Linespeeds for Sachet Insertion
• Concerns about 100% Placement of Sachet

– Foreign Object Presence in Package – Does not work with Liquid Products

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In Package Systems

• Oxygen Scavenger Incorporated in Multilayer Structure
• Strengths

– Eliminate “Foreign” Object in Package – Can use Normal Packaging Process Conditions – Can be Used with Wider Range of Products – i.e. Liquids

• Challenges

– Meeting Rate/Capacity Application Needs – Impact on Package Attributes

Mara Destro Session number 7733

SPO2 Structures/Uses

• Use in Combination with Barrier Packaging
• Rigid Containers
• Lids of Rigid Containers
• Bottles
• Films
• Closure Liners

37

Typical Applications

• Food with moisture:
• Refrigerated or Room Temperature Conditions
• Moist pet food
• Meat wrap
• Cheese wrap
• Shelf-stable entrees
• Retort Applications