New Stabilization Package for Controlled Rheology Polypropylene ...

New Stabilization Package for Controlled 

Rheology Polypropylene Fibers 

(Benchmarked against Phenol & Phenol-free Systems) 

J. Mara 1 , H.-J. Kwon 2 , J.-D. Kim 2 , J. Bayer 3 & K. Keck 2 

1 Songwon International Americas; USA 

2 Songwon Industrial, South Korea 

3 Songwon International, Switzerland 

SPE International Polyolefins Conference 2012

• Introduction to Auto-oxidation of Polyolefins 

• Degradation of Polypropylene (PP) 

• Classification of PP Fibers (by Songwon) 

� Stabilization Requirements for PP Fibers 

� Stabilization Strategies for PP Fibers 

� Technical Benchmarking vs. Phenol-containing & Phenol-free Systems 

� Summary 

Contents 


Introduction 

Simplified Auto-Oxidation Cycle of Polyolefins 

Polymer 

OH 

Oxygen 

Heat 

Shear 

UV 

Metal Ion (Mn + ) 

O 2 

H2O None Radicalic Products 

* 

Alkyl Radical 

Polymer 

OO* 

Peroxy Radical 

O* 

Alkoxy Radical 

HO * 

Hydroxy Radical 

SPE International Polyolefins Conference 2012 

OOH 

Hydroperoxide 

Heat 

UV 

Polymer

Introduction 

Concepts to Counter Auto-Oxidation of Polyolefins 

Free Radical 

Scavenging 

Peroxide 

Decomposition 

Phenolic 

Antioxidant + → + 

Aminic 

N 

* 

R 

Antioxidant + → N R + 

Phosphite 

Antioxidant P + → RO P OR + 

Thioester 

Antioxidant 

A 

RO 

R 

R 

OH 

C 

H 

OR 

B 

OR 

S R 

O 

S 

R 

OO* 

OO* 

OOH 

O* 

+ → + 

OOH 

+ → + 

SPE International Polyolefins Conference 

A 

R 

R 

C 

OOH 

O 

OR 

O 

S 

O 

B 

R 

S R 

O 

OOH 

OOH 

OH 

OH 

OH

Introduction 

Polymer 

Radical Scavenging 

OH 

H 2O 

Oxygen 

Heat 

Shear 

UV 

Metal Ion (Mn + ) 

HALS, Amine ? 

O 2 


HALS, Amine, AO 

Auto-Oxidation Mechanism 

Thermo-Oxidation 

* 

Alkyl Radical 

Polymer 

OO* 

Peroxy Radical 

O* 

Alkoxy Radical 

HO * 

Hydroxy Radical 



HALS, Amine, AO 

OOH 

Hydroperoxide 

Heat 

UV 

Polymer 

Peroxide 

Decomposition 

Phosphite, Thioester

Degradation of Polypropylene 

• PP is an unstable substrate 

• Industrially unsuitable w/o stabilizers 

• Undergoes uncontrolled thermo-oxidative degradation w/o stabilizers 

• Polymerization, processing, & service life conditions can vary … 


Degradation of Polypropylene 

PP will undergo different Degradation Mechanisms: 

• Processing/Conversion: 

• Concentration [ROO*] < Concentration [R*] 

• MW decreases; [Mw/Mn] narrows 

• Disproportioning of Alkyl Radicals (formation of c=c) 

• Storage/Service Life: 

• Concentration [ROO*] >> Concentration [R*] 

• MW decreases; [Mw/Mn] broadens 

• Formation of Carbonyl Groups 

• Different & Contradicting Stabilizer Reqirements 


Classification of Polypropylene Fiber 

Monofilament 

Slit Tape 

Staple Fiber 

Continuous Filament 

Spunbond 

Meltblown 

Reactor grade 

Normal 

Can be cracked 

Normal to broad 

Normal 

Normal to narrow 

Narrow 

0 10 20 30 40 50 60 70 80 

Melt Flow MFI 230°C/2.16 

Typically cracked 

1-Step CR 2-Step CR 

• PP fiber grades are supplied over a range of MW’s depending upon processing & 

conversion characteristics as well as required properties of the application. 

• Songwon classifies PP fiber grades by the conversion technology & by the presence 

(or absence) of peroxides for controlled degradation (Controlled Rheology). 

• Monofilament & Tape grades have low MFI’s which need to be maintained during 

compounding & conversion. 

• Meltblown & Spunbond grades have MFI’s that must be tailored in a post reactor 

operation via the use of peroxides (CR grades). 

• Bulk continuous filament & Staple grades are available as either reactor grades or CR 

grades. 


Narrow 

- 1500

Classification of Polypropylene Fibers 

Monofilament 

Slit Tape 

Staple Fiber 


Spunbond 

Reactor grade 

Normal 


Normal 


Narrow 

Meltblown Narrow - 1500 

0 10 20 30 40 50 60 70 80 


Reference: E.P. Moore; Polypropylene Handbook; Hanser Publishers (1996) 



Monofilament 

Slit Tape 

Staple Fiber 


Spunbond 

Reactor grade 

Normal 



Normal 


Narrow 

Meltblown Narrow - 1500 

0 10 20 30 40 50 60 70 80 





Monofilament 

Slit Tape 

Staple Fiber 


Spunbond 

Meltblown 

Reactor grade 

Normal 



Normal 


Narrow 

0 10 20 30 40 50 60 70 80 




Typically cracked 

1-Step CR 2-Step CR 

Narrow 

- 1500

Standard Post Reactor Extrusion 

Storage 

tank 

Peroxide 

(mainly liquid) 

Pump 

P 

Stabiliser & Peroxide Addition for CR-PP 

Stabiliser 

Single Additive, OPS 

or masterfluff 

Loss-in-weight 

feeder 

W W 

(Individual) additive streams 

High shear extruder 

Silo or 

discharge hopper 

Polymer main stream 


Polyolefin 

bulk feed 

Pelletizing & Storage

Separate Addition during Extrusion 

Storage 

tank 

Peroxide 

(mainly liquid) 

Pump 

P 

Stabiliser & Peroxide Addition for CR-PP 

Stabiliser 

Single Additive, OPS 

or masterfluff 

Loss-in-weight 

feeder 

W W 

High shear extruder 

Silo or 

discharge hopper 

Peroxide stream (first) 


Stabiliser stream (later) 

Polymer main stream 

Polyolefin 

bulk feed 

Pelletizing & Storage

Stabilization Requirements of PP Fibers 

• Excellent MW protection during compounding & conversion 

– Principle reason for addition of processing stabilizer 

• No interaction with peroxides (CR grades) 

– Peroxide interaction leads to strong antagonism w/processing stabilizer 

• Low initial color following compounding 

• Low color development following conversion 

• Low gas fade during conversion & storage 

– Potentially negatively affected by primary AO 

• Adequate storage stability (optional) 

• Outdoor UV stability (optional) 

– Easily adjustable by choice of HAS 

• Other (registrations, cost, industrial availability) 


Stabilization Requirements of PP Fibers 

• Performance requirements for PP fiber stabilization packages vary 

with the conversion technology & the need for CR grades. 

• An overview of the importance of the various requirements for the 

different PP fiber grades is given below: 

Compounding 

Conversion 

Service Life 

Monofilament 

Tape 

Staple (Reactor) 

(B) CF (Reactor) 

Excellent MW Preservation P P � � � � � � � 

Low Peroxide Interaction P P � � � � 

Low Initial Colour P P � � � � � � � � 

Low Colour Development P P P � � � � � � � � 

Low Gas Fading P � � � � � � 

Low Smoke & Fume P � � 

Good MW Protection- LTTS P � � � � � � � � 

Good MW Protection - UV P � � � � � � � � 

� Very important 

� Suitable; usually required 

� Required or not depending on end application 

Staple - CR 

(B) CF-CR 


Spunbond-CR 

Meltblown-CR 

Remark 

Only colour critical applications 

Depending on end application

Stabilization Strategies for PP Fibers 

February 26 th - February 29 th , 2012 

3 Alternatives for PP Fibers 

Grade Compounding Fiber Conversion Stabilization Strategy 

Reactor MW Preservation MW Preservation Excellent Processing 

Stability 

1 Step CR Controlled MW Decrease MW Preservation Optimum Balance of 

Good Processing Stability 

vs. Low Peroxide Interaction 

2 Step CR Controlled MW Decrease Controlled MW Decrease No or Minimal 

Processing Stability 


Selection Guide for PP Fiber Grades 

• Recommendations are grouped around the conversion technology & corresponding 

importance of stabilizer requirements as captured in previous slide. 

Classification 

Monofilament 

& Tape 

Staple - Reactor 

Continuous 

Filament (CF) - 

Reactor 

Staple - CR 

Continuous 

Filament (CF) - CR 

Spundbond 

Meltblown 

Songwon Product 

(ppm) 

Songnox 21B 

(1500 ~ 2000) 

Songnox 1790 + Songnox 

6260 [33:67](1000~1500) 

Songnox 21B 

(1500 ~ 2000) 

Songnox 331B 

(1500 ~ 2000) 

Songnox 3016 GR 

(1000 ~ 2000) 

Songnox 331B 

(1500 ~ 2000) 


(500 ~ 1500) 

Songnox 331B 

(1000 ~ 2000) 


(500 ~ 1500) 


[1:1] (300 ~ 600) 

Excellent MW preservation 

Low peroxide interaction 

Low initial color 

Low color development 

Criteria 

Low gas fading 

Low Fume & Smoke 


Good MW protection-LTTS 

● ○ ○ ○ 

Good MW protection-MI 

Remarks 

Not suitable for color sensitive 

applications 

● ○ ● Severe processing condition 

● ○ ○ ○ 

Not suitable for color sensitive 

applications 

● ○ ● ○ ○ ○ Offers improved color 

● ○ ● ● ● ● ● 

Offers best color 


● ○ ● ● ● ● ● 

Best color, Excellent balance 

MW preservation & Low peroxide 

interaction 


● ○ ● ● ● ● ● 

● ● ● ● ● ○ ○ 

Best color, Excellent balance 

MW preservation & Low peroxide 

interaction 

No peroxide interaction 

Very good color & gasfading 

Low Fume & Smoke 

● Recommended / Fulfills criterion completely / ○ Can be used 

[Green: very important / critical (in general), Yellow: very important / critical (selected end application) Gray: important / useful]

Songnox 3016 Characteristics 

• New AO package for color critical applications, including: 

– PP Fiber (Bulk Continuous Filament – Reactor & CR; Staple – Reactor & CR; & Spunbond 

applications) 

– Polyolefin Film applications (Not covered today) 

– Polyolefin Tape applications (Not covered today) 

– Thin Walled Injection Molding (TWIM) applications (Not covered today) 

• Provides an excellent balance between Processing Stability & Low Peroxide 

interaction. 

• The interaction with peroxide is significantly reduced compared to Phenol 

containing systems (i.e., Songnox 321B) & Phenol-free systems, including: 

– Irgastab FS 533 (Composition: FS042 + I-168 + C-2020) [1:10:3] 

– Irgastab FS 102 (Composition: FS042 + I-168 + T-622) [1:2:1] 

– Irgastab FS 410 (Composition: FS042 + C-944) [1:1] 

• Performance data in PP homopolymer (gas phase) / MFI (230 C/2.16 kg) ~4 to 6 

[dg/min] follows… 


Stabilizer Interaction with Peroxide in CR-PP 

No additive 


Songnox 321B 

Irgastab FS 533 



Substrate: PP homopolymer (gasphase) 

MFI 230/2.16 ~ 4 to 6 [dg/min] 

Compounding: N 2, 190 – 215 o C, TS 

Criterion: MFI after compounding 

4 8 12 16 20 24 28 32 

MFI (g/10min) 2.16kg/230 o C 


Stabilisation: 500 ppm Ca-stearate + 1000 ppm stabiliser 

Additivation: 490 ppm PO-4 

[2,5-Bis(t.-butylperoxy)-2,5-dimethylhexane]


Songnox 321B 




Low Gas Fading in CR-PP 


MFI 230/2.16 ~ 4 to 6 [dg/min] 


Exposure: 5hr at 60 o C under 5% NO x gas 

(KS K 0454) 

0 5 10 15 20 25 30 

Delta Yellowness Index 




[2,5-Bis(t.-butylperoxy)-2,5-dimethylhexane] 

Criterion: Delta YI


Songnox 321B 





MFI 230/2.16 ~ 4 to 6 [dg/min] 


Low Initial Color in CR-PP 

-4.0 -3.8 -3.6 -3.4 -3.2 -3.0 

Yellowness Index E 313 





Criterion: YI after compounding

Low Color Development during Processing 


Songnox 321B 





MFI 230/2.16 ~ 4 to 6 [dg/min] 


-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 

Yellowness Index E 313 


Pass 5 

Pass 3 

Pass 1 




Criterion: YI after multiple extursion Pass 1 ~ 5

Stabilisation of Controlled Rheology Polypropylene 

Methodology 

� Radar chart 

� Relative scale: 5 Best (outside) 

4 

3 Intermediate 

2 

1 Worst (inside, center) 



Easy Adjustment LTTS / UV 

Low Gas fading 

Excellent Processing Stability 

5 

4 

3 

2 

1 

Low Colour Development (Processing) 


Low Peroxide Interaction 

Low Initial Colour


Unstabilised Controlled Rheology PP 

Easy Adjustment LTTS / UV 

Low Gas fading 

Excellent Processing Stability 

5 

4 

3 

2 

1 

Low Colour Development (Processing) 


Low Peroxide Interaction 

Low Initial Colour

� Formulation: 

� Stabilisation Strategy: 

� Positioning: 

General Phenol Stabilizer System A 

� A [Songnox 317B] 

Composition: 3 parts SN1680 + 1 part SN1076 

� [Phenolic AO + Phosphite] synergism 

� Standard phenolic AO 

� Standard phosphite 

� Partially optimised composition & ratio 

� Standard AO package from IM or extrusion 



A [Songnox 317B] 1000 ppm 





General Phenol Stabilizer System B 

� B [Songnox-321B] 

Composition: 2 parts SN1680 + 1 part SN3114 

� [Phenolic AO + Phosphite] synergism 

� Phenolic AO with reduced color formation 

� Partially optimised composition & ratio 

� Improved processing stability 




B [Songnox 321B] 1000 ppm 





Phenol-Free Stabiliser System C 

� C [Hydroxylamine + HAS / FS 410] 

� Elimination of phenolic AO (color source) 

� Processing stability based only on hydroxylamine 

� No synergistic effect 

� Conversion independant of service life 

� Hyperactive processing stabiliser 





C [FS 410] 1000 ppm 





Phenol-Free Stabiliser System D,E 

� D [Hydroxylamine + Phosphite + HAS / FS 102] 

� E [Low hydroxylamine + Phosphite + HAS / FS 533] 

� Elimination of phenolic AO (colour source) 

� ‘‘Kinetic’’ balance Processing vs. Peroxide 

� Synergistic effect 

� Conversion independant of Service Life 

� C System formulated with low level of hyperactive 

processing stabiliser 





C [FS 410] 1000 ppm 

D [FS 102] 1000 ppm 

E [FS 533] 1000 ppm 





New Color Critical Stabiliser System 

� F [Songnox 3016 GR] 

� Elimination of phenolic AO (colour source) 

� ‘‘Kinetic’’ balance Processing vs. Peroxide 

� Synergistic effect 

� Conversion independant of Service Life 

� No hyperactive processing stabiliser 





C [FS 410] 1000 ppm 

D [FS 102] 1000 ppm 

E [FS 533] 1000 ppm 

F [Songnox 3016] 1000 ppm 


Summary 

• PP in general must be stabilized during compounding, processing, 

storage, and service life. 

• The stabilization of CR-PP during compounding and conversion is 

rather complex. 

• While efficient protection of the PP is easily achievable via 

stabilizers with high molar activity & reaction kinetics, peroxides may 

also be added in order to degrade the PP in a controlled manner, 

yielding grades with lower MW & narrower MWD’s. 

• In this work, we introduced a powerful new AO package for CR-PP 

that provides excellent balance between processing stability, color 

suppression, and low peroxide interaction. 

• While the scope of today’s presentation was limited to CR-PP fiber 

applications, the technology is also applicable to other applications 

such as TWIM where low peroxide interaction and low color 

development are critical.

New Stabilization Package for Controlled Rheology Polypropylene ...

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