additives for polyolefins: chemistry involved and ...€¦ · 2, 65%rh out - 100%rh in 0.0000...

Additives for polyolefins: chemistryinvolved and innovative effects

Mara DestroIntelligent packaging; session number7733

Mara DestroSession number 7733

Outline of Presentation

Weatherability of HALS in LLDPE Film and Impact of PPA on the Performance of HALS Oxygen Scavengers in Packaging Applications


Part I

Weatherability of HALS in LLDPE Film and Impact of Polymer Processing Aids

on the Performance of HALS


Polymer Processing Additives (PPA)

Eliminate Melt Fracture

Reduce Operating Pressure

Alleviate Die Build- Up

Reduction in Gel Formation

Typically Fluoroelastomers or Mixture with PEG


Hindered Amine Light Stabilizer (HALS)Widely used for outdoor applicationsFree radical scavengersEffective in high surface area applications (Films)However, HALS have been documented to have interactions with PPAIs it possible to use HALS and PPA together without having negative interactions?A continuation of the previous workThe HALS in this study: more according to current recommendations


R* H

ROO·R=O + ROH

R·

[Oxidation]

R

NO R

NO·

RR

NR*

[H+]

R

N+

XNOTE: 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 AminesUV Stabilization via Free Radical Scavenging


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


Structures of Various Hindered Amines

N

N

N

N

NNN

N

H

H H

(CH2)6

n

N

N N

N

N

N

NN

R R

H

R

R ]2-

NN CH3

C4H9

R =

N

O

OO

O

n

HALS-3

HALS-5

HALS-4HALS-1

HALS-2

N

N

N

NN

NN

OO

R =

C4H9C4H9

NHN NH

N

R R

H R

NN

NN

N

NH

N N

N

N

NH

N

NH

N NH

NN

N

N

N

H

NN N

n


0 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


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


Performance of HALSXenon Weathering of zn-LLDPE (w/ 1500 ppm HALS, No PPA)

0

25

50

75

100

125

0 2000 4000 6000 8000Hours in Xenon Weatherometer

% R

etai

ned

Elon

gatio

n

none

HA-3 (N-H)

HA-1 (N-R)

HA-6 (NR+NH)

HA-7 (NR+NCH3)

HA-8 (N-OR)


Influence of PPA on HALSXenon Weathering of zn-LLDPE (w/ 1500 ppm HALS; 900 ppm PPA)

0

25

50

75

100

125

0 2000 4000 6000 8000Hours in Xenon weatherometer

% R

etai

ned

Elo

ngat

ion

none

HA-3 (N-H)

HA-1 (N-R)

HA-6 (NR+NH)

HA-7 (NR+NCH3)

HA-8 (N-OR)


Gas Fade Discoloration with PPAGas Fade Aging of zn-LLDPE: (w/1500 ppm HALS; 900 ppm PPA)

0

5

10

15

0 5 10 15 20 25 30Day in Gas Fade Chamber at 60°C

YI C

olor

none

HA-3 (N-H)

HA-1 (N-R)

HA-6 (NR+NH)

HA-7 (NR+NCH3)

HA-8 (N-OR)


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


ConclusionHMW 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-3PPA has slight positive impact: HALS-8

It is possible to use HALS and PPA together without having negative interaction (selectively)


16

Part IIOxygen Scavenging Technologies for Food Packaging Applications

• Review of Oxygen Scavenger Technology

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


17

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


18

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


19

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


20

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


21

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?


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%

0 20 30 40 50 60 75 100Relative Humidity (%)

SPO

2O

xyge

n A

bsor

ptio

n C

apac

ity


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


25

SPO2 in Packaging StructureRetorted Applications


26

Barrier PerformanceBarrier 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

0 10 20 30 40 50 60 70Days

O2T

R (c

c/pa

ckag

e.da

y.at

m) Packaging with no SPO2 no retort - theoretically

Packaging with SPO2 after retort - measured

Packaging with no SPO2 after retort - theoretically


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 optimum synergic barrier performance in retort application


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!


Backup Slides


Gas Fading

OH OH

O

NO2 NO2

NO2

O

-HONO

O

OH

OH

-HONONO2

O

O

OH

NO2

O

NO2

2RO.-2ROH

O

N+

O

OOH-

H+

slightly yellow strong yellow

vis-absorption106’000 [l*mol-1cm-1]


Typical Structure of Polymer Processing Aid

F

F H

H

CF3

F

F

Fnm

C C CC

δ−

δ− δ−

δ−δ+

δ+


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


33

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


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


35

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


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

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