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New Stabilization Package for Controlled Rheology Polypropylene Fibers
(Benchmarked against Phenol & Phenol-free Systems)
SPE International Polyolefins Conference 2012
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
• 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
SPE International Polyolefins Conference 2012
SPE International Polyolefins Conference 2012
OH
H2O
O2
OO*
Peroxy Radical
OOH
Hydroperoxide
*
Alkyl Radical
O*
HO *
Alkoxy Radical
Hydroxy Radical
Polymer
Polymer
Polymer
None Radicalic Products
Oxygen Heat
Shear UV
Metal Ion (Mn+)
Heat UV
Simplified Auto-Oxidation Cycle of Polyolefins
Introduction
Concepts to Counter Auto-Oxidation of Polyolefins
Free Radical Scavenging
Phenolic Antioxidant + → +
Aminic Antioxidant + → +
Peroxide Decomposition
Phosphite Antioxidant + → +
Thioester Antioxidant
+ → + + → +
OH
B A
C
OO* O*
B A
C
OOH
N H
R
OO* * N R
OOH
P OR
OR
RO
OOH P OR
O
RO
OR
OH
S R R
OOH
S R
O
R
S R
O
R
O
OH
OH
S R
O
R
OOH
Introduction
SPE International Polyolefins Conference
OH
H2O
O2
OO*
Peroxy Radical
OOH
Hydroperoxide
*
Alkyl Radical
O*
HO *
Alkoxy Radical
Hydroxy Radical
Polymer
Polymer
Polymer
Oxygen Heat
Shear UV
Metal Ion (Mn+)
Heat UV
Radical Scavenging HALS, Amine ?
Radical Scavenging HALS, Amine, AO
Radical Scavenging HALS, Amine, AO
Radical Scavenging
Auto-Oxidation Mechanism Thermo-Oxidation
Peroxide Decomposition
Phosphite, Thioester
SPE International Polyolefins Conference 2012
Introduction
• 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
SPE International Polyolefins Conference 2012
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
Degradation of Polypropylene
SPE International Polyolefins Conference 2012
Classification of Polypropylene Fiber
• 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.
0 10 20 30 40 50 60 70 80
Melt Flow MFI 230°C/2.16
Monofilament
Slit Tape
Staple Fiber
Continuous Filament
Spunbond
Meltblown
Typically cracked
- 1500
Can be cracked
Reactor grade
Narrow
Narrow
Normal to narrow
Normal to broad
Normal
Normal
1-Step CR 2-Step CR
SPE International Polyolefins Conference 2012
Classification of Polypropylene Fibers
SPE International Polyolefins Conference 2012
0 10 20 30 40 50 60 70 80
Melt Flow MFI 230°C/2.16
Reference: E.P. Moore; Polypropylene Handbook; Hanser Publishers (1996)
Monofilament
Slit Tape
Staple Fiber
Continuous Filament
Spunbond
Meltblown - 1500
Reactor grade
Narrow
Narrow
Normal to narrow
Normal to broad
Normal
Normal
Classification of Polypropylene Fibers
SPE International Polyolefins Conference 2012
0 10 20 30 40 50 60 70 80
Melt Flow MFI 230°C/2.16
Reference: E.P. Moore; Polypropylene Handbook; Hanser Publishers (1996)
Monofilament
Slit Tape
Staple Fiber
Continuous Filament
Spunbond
Meltblown - 1500
Can be cracked
Reactor grade
Narrow
Narrow
Normal to narrow
Normal to broad
Normal
Normal
Classification of Polypropylene Fibers
SPE International Polyolefins Conference 2012
0 10 20 30 40 50 60 70 80
Melt Flow MFI 230°C/2.16
Reference: E.P. Moore; Polypropylene Handbook; Hanser Publishers (1996)
Monofilament
Slit Tape
Staple Fiber
Continuous Filament
Spunbond
Meltblown
Typically cracked
- 1500
Can be cracked
Reactor grade
Narrow
Narrow
Normal to narrow
Normal to broad
Normal
Normal
1-Step CR 2-Step CR
Standard Post Reactor Extrusion
SPE International Polyolefins Conference 2012
Stabiliser & Peroxide Addition for CR-PP
W W
Peroxide (mainly liquid)
Stabiliser Single Additive, OPS
or masterfluff
Loss-in-weight feeder
(Individual) additive streams
Polyolefin bulk feed
Polymer main stream
High shear extruder Pelletizing & Storage
Silo or discharge hopper
P
Storage tank
Pump
Separate Addition during Extrusion
SPE International Polyolefins Conference 2012
Stabiliser & Peroxide Addition for CR-PP
W W
Peroxide (mainly liquid)
Stabiliser Single Additive, OPS
or masterfluff
Loss-in-weight feeder
Stabiliser stream (later)
Polyolefin bulk feed
Polymer main stream
High shear extruder Pelletizing & Storage
Silo or discharge hopper
P
Storage tank
Pump
Peroxide stream (first)
Stabilization Requirements of PP Fibers
SPE International Polyolefins Conference 2012
• 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:
Com
poun
ding
Con
vers
ion
Serv
ice
Life
Mon
ofila
men
tTa
pe
Stap
le (R
eact
or)
(B) C
F (R
eact
or)
Stap
le -
CR
(B) C
F-C
R
Spun
bond
-CR
Mel
tblo
wn-
CR
Remark
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
Depending on end application
Only colour critical applications
SPE International Polyolefins Conference 2012
SPE International Polyolefins Conference 2012 February 26th - February 29th, 2012
Stabilization Strategies for PP Fibers
SPE International Polyolefins Conference 2012
3 Alternatives for PP Fibers
Grade Compounding Fiber Conversion Stabilization Strategy
Reactor MW Preservation MW Preservation Excellent ProcessingStability
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 MinimalProcessing Stability
SPE International Polyolefins Conference 2012
Selection Guide for PP Fiber Grades
Criteria
Classification Songwon Product (ppm)
Exce
llent
MW pr
eserv
ation
Low
perox
ide in
terac
tion
Low
initia
l colo
r
Low
color
deve
lopme
nt
Low
gas f
ading
Low
Fume
& S
moke
Good
MW
prote
ction
-LTTS
Good
MW
prote
ction
-MI
Remarks
Songnox 21B (1500 ~ 2000) ● ○ ○ ○ Not suitable for color sensitive
applications Monofilament & Tape
Songnox 1790 + Songnox 6260 [33:67](1000~1500) ● ○ ● Severe processing condition
Songnox 21B (1500 ~ 2000) ● ○ ○ ○ Not suitable for color sensitive
applications
Songnox 331B (1500 ~ 2000) ● ○ ● ○ ○ ○ Offers improved color
Staple - Reactor Continuous Filament (CF) - Reactor
Songnox 3016 GR (1000 ~ 2000) ● ○ ● ● ● ● ● Offers best color
Songnox 331B (1500 ~ 2000) ● ○ ● ○ ○ ○ Offers improved color Staple - CR
Continuous Filament (CF) - CR Songnox 3016 GR
(500 ~ 1500) ● ○ ● ● ● ● ● Best color, Excellent balance MW preservation & Low peroxide interaction
Songnox 331B (1000 ~ 2000) ● ○ ● ○ ○ ○ Offers improved color
Spundbond Songnox 3016 GR (500 ~ 1500) ● ○ ● ● ● ● ●
Best color, Excellent balance MW preservation & Low peroxide interaction
Meltblown Songnox 3016 GR [1:1] (300 ~ 600) ● ● ● ● ● ○ ○
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]
• Recommendations are grouped around the conversion technology & corresponding importance of stabilizer requirements as captured in previous slide.
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…
SPE International Polyolefins Conference 2012
Substrate: PP homopolymer (gasphase) MFI 230/2.16 ~ 4 to 6 [dg/min] Compounding: N2, 190 – 215oC, TS Criterion: MFI after compounding
Stabilisation: 500 ppm Ca-stearate + 1000 ppm stabiliser Additivation: 490 ppm PO-4 [2,5-Bis(t.-butylperoxy)-2,5-dimethylhexane]
Stabilizer Interaction with Peroxide in CR-PP
4 8 12 16 20 24 28 32
MFI (g/10min) 2.16kg/230oC
No additive
Songnox 3016 GR
Songnox 321B
Irgastab FS 102
Irgastab FS 410
Irgastab FS 533
SPE International Polyolefins Conference 2012
Substrate: PP homopolymer (gasphase) MFI 230/2.16 ~ 4 to 6 [dg/min] Compounding: N2, 190 – 215oC, TS Exposure: 5hr at 60oC under 5% NOx gas (KS K 0454)
Stabilisation: 500 ppm Ca-stearate + 1000 ppm stabiliser Additivation: 490 ppm PO-4 [2,5-Bis(t.-butylperoxy)-2,5-dimethylhexane] Criterion: Delta YI
Low Gas Fading in CR-PP
Songnox 3016 GR
Songnox 321B
Irgastab FS 102
Irgastab FS 410
0 5 10 15 20 25 30
Delta Yellowness Index
Irgastab FS 533
SPE International Polyolefins Conference 2012
Substrate: PP homopolymer (gasphase) MFI 230/2.16 ~ 4 to 6 [dg/min] Compounding: N2, 190 – 215oC, TS
Stabilisation: 500 ppm Ca-stearate + 1000 ppm stabiliser Additivation: 490 ppm PO-4 [2,5-Bis(t.-butylperoxy)-2,5-dimethylhexane] Criterion: YI after compounding
Low Initial Color in CR-PP
-4.0 -3.8 -3.6 -3.4 -3.2 -3.0
Yellowness Index E 313
Songnox 3016 GR
Songnox 321B
Irgastab FS 102
Irgastab FS 410
Irgastab FS 533
SPE International Polyolefins Conference 2012
Substrate: PP homopolymer (gasphase) MFI 230/2.16 ~ 4 to 6 [dg/min] Compounding: N2, 190 – 215oC, TS
Stabilisation: 500 ppm Ca-stearate + 1000 ppm stabiliser Additivation: 490 ppm PO-4 [2,5-Bis(t.-butylperoxy)-2,5-dimethylhexane] Criterion: YI after multiple extursion Pass 1 ~ 5
Low Color Development during Processing
-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0
Yellowness Index E 313
Pass 5
Pass 3
Pass 1
Songnox 3016 GR
Songnox 321B
Irgastab FS 102
Irgastab FS 410
Irgastab FS 533
SPE International Polyolefins Conference 2012
Stabilisation of Controlled Rheology Polypropylene Methodology
Radar chart Relative scale: 5 Best (outside)
4 3 Intermediate 2 1 Worst (inside, center)
SPE International Polyolefins Conference 2012
1
2
3
4
5Excellent Processing Stability
Low Peroxide Interaction
Low Initial Colour
Low Colour Development (Processing)
Low Gas fading
Easy Adjustment LTTS / UV
Stabilisation of Controlled Rheology Polypropylene
SPE International Polyolefins Conference 2012
1
2
3
4
5Excellent Processing Stability
Low Peroxide Interaction
Low Initial Colour
Low Colour Development (Processing)
Low Gas fading
Easy Adjustment LTTS / UV
Stabilisation of Controlled Rheology Polypropylene Unstabilised Controlled Rheology PP
SPE International Polyolefins Conference 2012
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
SPE International Polyolefins Conference 2012
Stabilisation of Controlled Rheology Polypropylene
A [Songnox 317B] 1000 ppm
SPE International Polyolefins Conference 2012
Formulation:
Stabilisation Strategy:
Positioning:
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
SPE International Polyolefins Conference 2012
Stabilisation of Controlled Rheology Polypropylene
A [Songnox 317B] 1000 ppm B [Songnox 321B] 1000 ppm
SPE International Polyolefins Conference 2012
Formulation:
Stabilisation Strategy:
Positioning:
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
SPE International Polyolefins Conference 2012
Stabilisation of Controlled Rheology Polypropylene
A [Songnox 317B] 1000 ppmB [Songnox 321B] 1000 ppm C [FS 410] 1000 ppm
SPE International Polyolefins Conference 2012
Formulation:
Stabilisation Strategy:
Positioning:
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
SPE International Polyolefins Conference 2012
Stabilisation of Controlled Rheology Polypropylene
A [Songnox 317B] 1000 ppm B [Songnox 321B] 1000 ppm C [FS 410] 1000 ppm D [FS 102] 1000 ppm E [FS 533] 1000 ppm
SPE International Polyolefins Conference 2012
Formulation:
Stabilisation Strategy:
Positioning:
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
SPE International Polyolefins Conference 2012
Stabilisation of Controlled Rheology Polypropylene
A [Songnox 317B] 1000 ppm B [Songnox 321B] 1000 ppm C [FS 410] 1000 ppm D [FS 102] 1000 ppm E [FS 533] 1000 ppm F [Songnox 3016] 1000 ppm
SPE International Polyolefins Conference 2012
SPE International Polyolefins Conference 2012
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.
SPE International Polyolefins Conference 2012