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


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.

5

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


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


Sulfur/acc versus peroxide curesystems

Scorch Retardation

*Depends on type ofperoxide

9


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


High temperature resistance, durability and low compression set, are directly related to C-C bonds!

Scorch retardation inPeroxide Cure


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


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



Perkadox PD-50S-PS in VMQ vs Perkadox PM-50S-PS in VMQ:Compounds Stored: 9 days @ 40˚C

Importance of selecting the correctperoxide


The higher the peroxide dosage level the lower the scorch safety!

Importance correct peroxide dosagelevel (Mooney scorch & Rheo scorch)


Example incorrect compoundstorage conditions on Rheo-scorch

No or hardly thermoplastic flow!


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: ?


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!


CH 3 O H

O HOH

N OOH

Hypotheses reactivity scorchretarders TBHQ & OH-TEMPO


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


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)


Cur

e tim

e(m

in.)


Scorch retardation – EPDM recipeMBTS – TAC concept (Trigonox 29)


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%!!


Scorch retardation – EPDM recipeTBHQ vs OH-TEMPO (Trigonox 101)

Scorch retardation – EPDM recipeTBHQ vs OH-TEMPO (Trigonox 101)

29Scorch Retardation

Base recipe:

EPDM 100N-550 70N-772 70Par. Oil 50Trigonox 101-45B 6.1TBHQ levels 0.1 – 0.2


Simulation scorch by means of“Rheovulcameter”

Ramification mold(ex Göttfert)

Courtesey: Engel - Austria


Simulation scorch by means of“Rheovulcameter”

Reference TBHQ (0.2 phr) OH-TEMPO (0.2 phr)


Importance of good scorch safety inperoxide cure

Price (GBP/kg)

Goal: Zero Defects

102 pcs O-rings

Courtesey: Prof. J. Busfield


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.


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]

mailto:[email protected]




Scorch Retardation in Peroxide Cure · EPDM - 12.5 phr Trigonox 17-40 160°C Reference 170°C...

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