Scorch Retardation in Peroxide Cure · EPDM - 12.5 phr Trigonox 17-40 160°C Reference 170°C...
Transcript of Scorch Retardation in Peroxide Cure · EPDM - 12.5 phr Trigonox 17-40 160°C Reference 170°C...
Enhanced Scorch Safetyin Peroxide Cure Systems
Leo NijhofMay-16, 2018
Scorch Retardation 2
Update AkzoNobel Specialty Chemicals
Sulfur/acc versus Peroxide Cure Systems
Challenges for Peroxide Cure
Scorch Retardation and the “do it yourself” Approach
Content
Update AkzoNobel –Specialty Chemicals
Scorch Retardation 4
Dual-track process
Scope of requestedshareholder approval
Private sale
Demerger
IPO(Initial Public Offering)
Paints Coatings Specialty Chemicals(all BU’s)
Transaction scope
Internal separation External separation
Organizational overview(Status March-2018)
To create a focused chemicals business
For now: Business as usualà AkzoNobel & Safic Alcan UK!
The final completion of the sale (closing) is expected to take place before the end of 2018, subject to customaryclosing conditions and the relevant regulatory approvals.
On March 27, AkzoNobel announced the intended sale of Specialty Chemicals to The Carlyle Group and GIC.
They have significant experience in the chemicals industry, and they share our values regarding health,safety, innovation and sustainability.
The Carlyle Group was selected because of their interest in acquiring Specialty Chemicals as a whole and theirfocus on driving growth, job creation and long-term financial success as a responsible investor.
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Separation of Specialty Chemicals(Status May-2018)
Specialty Chemicals:Industries worldwide rely on our products, for the production of everyday essentials suchas paper, polymers, detergents, and ingredients for the construction, agricultural, and pharmaceutical sectors.
Scorch Retardation
Sulfur/acc vs PeroxideCure Systems
Versatile curing/vulcanization options!Sulfur crosslinks do act as spacer (S-bridge) in cured rubber. Sulfur crosslinks do have thepossibility to re-arrange!
This makes sulfur cure system the preferred choice in those applications where;Stress / StrainDynamicsHigh tearFatigue to failure
Example: Tire applications!
Prime importance!
Main reasons to select aSulfur/acc cure system
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Recipes are relatively simpleà one curative can do the jobHigh compounding & processing temperatures possible for selective peroxides (± 130°C)Storage stability peroxide systems outperform sulfur cure containing compoundsNo reversion due to the formation of stable C-C bonds
Therefore frequently applied where demand is high for;Resistance against deformation (compression set)High temperature resistance (no reversion)To cure saturated rubbersBetter color-stability of productsCo-cure with reactive co-agents, plasticizers, oils(less leachable components / less blooming)
The C-C bond is however rigidà Therefore primary use in static applications!
A known drawback of peroxide cure: Limits in ‘manipulation’ during curing/vulcanization!
Main reasons to select Peroxide cure
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Sulfur/acc versus peroxide curesystems
Scorch Retardation
*Depends on type ofperoxide
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Cure kinetics:Scorch and cure time are lessflexible as compared to sulfur/accsystems, since they are determinedmainly by temperature!
Crusading against PeroxidePrejudices!
Remember!
Type of bond Peroxide Sulfur + accelerators
Conv. System E.V. System
Dis. Energy(KJ/mol)
C-C
Mono-Sulphidic
Di-Sulphidic
Poly-Sulphidic
100
-
-
-
-
10
40
50
-
75
25
-
352
285
268
<268
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High temperature resistance, durability and low compression set, are directly related to C-C bonds!
Scorch retardation inPeroxide Cure
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Importance of scorch safetyWhy do we need it?
Aspects impacting Scorch Safety
Time
Torq
ue
The recipe &compounding
(mixing/milling)
storage&
transport
Extrusionor Injectionconditions
Safetyfactor Mould flow Curing
Scorch time ts2X
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Practical methods to overcomescorch:By selecting the right recipe, including grade & concentration of peroxide
Might become a penalty on cure temperature & time!
Temperature control (extra cooling during compounding, storage, shipment)penalty on product output & costs
Buying ready made scorch retarded peroxide formulationsnot always practical and applicable for all applicationsNot available for every peroxide formulation
Note: Peroxides do react in function of time & temperature (cure kinetics)Every 10°C temp increase, will almost double the reaction speed!
Regular used peroxides for rubbercrosslinking
CH3
CH3
CH3
O OCH3
CH3
CH2 CH2
CH3
CH3
O OCH3
CH3
CH3
CH3
CH3
CH3
O OCH3
CH3
CH3
CH3
O OCH3
CH3
CH3
CH3
CH3
O OCH3
CH3
OO O
CH3
CH3
CH3
OO O O
Cl
C l
OO
Cl
C lO O
Perkadox PD, 90°C
Trigonox 29, 150°CTrigonox 101, 175°C
Perkadox 14, 175°C
Perkadox BC (DCP), 170°C
Trigonox C, 140°C
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Perkadox PD-50S-PS in VMQ vs Perkadox PM-50S-PS in VMQ:Compounds Stored: 9 days @ 40˚C
Importance of selecting the correctperoxide
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The higher the peroxide dosage level the lower the scorch safety!
Importance correct peroxide dosagelevel (Mooney scorch & Rheo scorch)
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Example incorrect compoundstorage conditions on Rheo-scorch
No or hardly thermoplastic flow!
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Impact temperature on scorch safety& cure speed
Trigonox 17(Peroxide dosage 1% in EVA)
0
0.05
0.1
0.15
0.2
0.25
0.3
0 5 10 15 20 25 30
time [min]
torq
ue [N
m]
140°C150°C160°C
Scorch area!
T90: ?
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How to manipulate the onset of cure?
Scorch retardation is possible by adding H-donor agents, for example;For example antidegradants e.g. BHT = Butylated Hydroxy Toluene, TBHQ =
tert.butylhydroxy quinone)Sulfur derivatives (MBTS, TMTD – take care with smell)Stable free (transfer) radicals agents [living radicals]
Working principal;Take away the initial formed radicals, or“Transform” initial formed radicals into an in-active system which releases the radicalsafter applying more energy (temperature)
Strong market desire for a easy “do-it-yourself-systems”;Every compound needs to match its specific characteristicsThe need for selection freedom in type of scorch retarderCompound optimization on demand
Scorch retarding systems knownfrom literatureBHT (Butylated hydroxy toluene)Extra peroxide and/or co-agents might be needed!
Sulfur derivatives + Co-agents MBTS / TMTD / TAC / EDMA
TBHQ (tert. Butylhydroxy quinone)(e.g. Tenox TBHQ ex Eastman over Safic Alcan)
OH-TEMPO (4-hydroxy-2,2,6,6,-tetramethyl-1-piperidinyloxy)à Patented!
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CH 3 O H
O HOH
N OOH
Hypotheses reactivity scorchretarders TBHQ & OH-TEMPO
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TBHQ: Tert.butylhydroquinone (cas number: 1948-33-0). Also used as food additive (E-319)
Hydroxy TEMPO: 4-Hydroxy-2,2,6,6-tetramethylpiperidinoxyl (cas number: 218-760-9)
R HO HOH OOR+
s ta b le e n d p ro d u c t
+2 2
N OOH R N OOH R N OOH R+
s ta b le b e lo w 1 3 0 °C
+D T
> 1 3 0 °C
s ta b le ra d ic a l +re a c t iv e ra d ic a l
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Criteria scorch retarding additivesSelection criteria for suitable scorch retarders;
Should bring optimal balance between scorch retardation and cure time
Crosslink density should not (or hardly) be impacted
Additives should be freely (commercial) available
Should work at low dosage levels and not be too expensive (what is expensive?)
Should not negatively impact final product characteristics(safety, dispersion, smell, physical properties, etc.)
Example Crosslink variability of an EPDMinjection molding compound (+ BHT)
11 phr Trigonox 29-40
11 phr Trigonox 29-40 + 0.4 phr BHT
10
8
6
0
150 160 200170 180 190
4
2
Temp. (°C)
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Cur
e tim
e(m
in.)
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Scorch retardation – EPDM recipeMBTS – TAC concept (Trigonox 29)
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Scorch retardation – EPDM recipeMBTS – TAC concept (Trigonox 29)
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Scorch retardation – EPDM recipeMBTS – EDMA concept (Trigonox 17)
0,0
0,5
1,0
1,5
2,0
2,5
3,0
0 1 2 3 4 5 6
Torq
ue (N
m)
Time (min)
EPDM - 12.5 phr Trigonox 17-40
160°C Reference170°C Reference170°C 2 phr EDMA, 1 phr MBTS
Formulation Reference Scorch Retarded
EPDMN-550N-772Par. OilTrigonox 17-40MBTSEDMA
100707050
12.5--
100707050
12.512
Rheometer data:
Ts2 @ 160°CTs2 @ 170°C
T90 @ 160°CT90 @ 170°C
0.480.32
6.42.5
-0.47
-2.6
At equal scorch time, a cure time saving of > 50%!!
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Scorch retardation – EPDM recipeTBHQ vs OH-TEMPO (Trigonox 101)
Scorch retardation – EPDM recipeTBHQ vs OH-TEMPO (Trigonox 101)
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Base recipe:
EPDM 100N-550 70N-772 70Par. Oil 50Trigonox 101-45B 6.1TBHQ levels 0.1 – 0.2
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Simulation scorch by means of“Rheovulcameter”
Ramification mold(ex Göttfert)
Courtesey: Engel - Austria
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Simulation scorch by means of“Rheovulcameter”
Reference TBHQ (0.2 phr) OH-TEMPO (0.2 phr)
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Importance of good scorch safety inperoxide cure
Price (GBP/kg)
Goal: Zero Defects
102 pcs O-rings
Courtesey: Prof. J. Busfield
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Recommendation & ConclusionsScorch rertarding systems, for peroxide cure, can be used relatively easy by recipe- andcompound designers themselves. Principal of pepper and salt.
Systems based on H-donor + co-agent, needs fine-tuning in dosage levels per selectedcure system
The usage of TBHQ as scorch retarding additve needs careful attention, effectiveness isvery high. Stay below 0.3 phr!
Scorch retarding systems based on hydrogen donating additives (e.g. TBHQ) and radicaltrapping & releasing agents (e.g. OH-TEMPO) react different, both can be applied.
At relatively high molding temperatures the radical trapping & releasing agent (OH-TEMPO) gets instable and releases radicals again.
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Safic – Alcan UK Ltd:
Phil Griffin (Business Manager)Tel: +44 (0) 1925 848135Mob phone: +44 7801 [email protected]
David Hayman (Business Manager)Tel: +44 (0) 1925 848135Mob phone: +44 (0) 7801 [email protected]
For further info
AkzoNobel - Polymer Chemistry
Tony Minshull (Account Manager)Tel: +31 (0) 889 696 489Mob phone: +31 (0) 650 643 [email protected]
Leo Nijhof (for technical information)Tel: +31 (0) 570 679 237Mob phone: +31 (0) 651 120 [email protected]