Rubber Division, ACS Fall 2009 Meeting Pittsburgh

1 MLPC International / An original anti-reversion curing agent/Rubber Division Fall 2009/ Pittsburgh

Rubber Division, ACSFall 2009 Meeting

Pittsburgh


An Original Anti-Reversion

Nitrosamine-Free Curing Agent as an Alternative to TMTD


1)Company introduction2) Reference compound3) Experimental design4) Conclusion

CONTENTS

An Original NR Anti-Reversion Nitrosamine-free Curing Agent



CONTENTS



MLPC International is located in France, in the southwest, near by Bordeaux.

MLPC supplies various curing agents either in powder form or in Mixland form (pellets or

slabs).

MLPC is a world leader for predispersed curing agents (Mixland+)

Discover MLPC International


MLPC ‘s facilities

MLPC belongs to the french chemical group

Discover MLPC International


Why this survey?

-NR is a renewable material, but its heat resistance needs to be improved

-To save curing energy, it is important to reduce energy consumption by cured part:for instance, by shortening the cure time.

MLPC’s goal is to offer answers to these challenges



1)Company introduction2) Reference compound3) Experimental design4) Improved recipe5) Conclusion

CONTENTS



NR reference compound

*= included stearic acid**= nitrosamine generator

FORMULATION With TMTD 80 GA

(= T compound)

NR base * 164

MIXLAND+ ZnO 90 GA 5

MIXLAND+ TMTD** 80 GA 2

MIXLAND+ S 80 GA 0.5

MIXLAND+ TBP 75 GA -

MIXLAND+ CBS 80 GA -

MIXLAND+ DPG 80 GA -

The main goal is to replace TMTD



RHEOMETRIC FEATURES of reference compound T (with TMTD) at VARIOUS curing temperatures.

Temperature

Ts2 (min)

T 90 (min)

Mx @ Tc50*

MH-ML

(dN.m)

Reversion index

(100+1.5)

160°C 1.08 1.33 15 8.65 0.205

170°C 0.76 0.98 32 9.49 0.92

180°C 0.64 0.73 38 9.5 1.06

t 3 scorch time @ 125°C = 9.38 min

Note: To increase cure temperature from 160 to 180°C cuts the cure time by 2 roughly




CONTENTS



NR reference compound

*= included stearic acid**= nitrosamine generator

FORMULATION With TMTD 80 GA (= T compound)

With TMTD alternative

NR base * 164 164

MIXLAND+ S 80 GA 0.5 0.5

MIXLAND+ TMTD** 80 GA 2 -

MIXLAND+ ZnO 90 GA 5 5

MIXLAND+ TBP 75 GA - variable

MIXLAND+ CBS 80 GA - variable

MIXLAND+ DPG 80 GA - variable



Structure of Mixland TBP 75 GA

OH

tert-Bu

OH

Sx

tert-Buy

OH

Sx

tert-Bu

X average= 2.1, Y average= 5

It is based on a modified poly-ter-butyl-phenol disulfide


No Nitrogen=>cannot generate

Nitrosamine

14 MLPC International / An original anti-reversion curing agent/Rubber Division Fall 2009/ PittsburghRubber Chem Conference, Birmingham - 08 & 09 Nov. 2004 14

3X3 experimental cubic volume design

(+1,+1,+1)

(-1,-1,-1)

(-1,+1,-1)

(-1,+1,+1)

(+1,-1,-1)

(0,0,0)(+1,-1,+1)


How to proceed?


3X3 experimental design

Variable Ingredient Quantity level in phr

X1 Mixland+ TBP 75 GA

Co-ordinates (-1; 0; +1)

= 1; 2; 3 phr

X2 Mixland + CBS 80 GA


= 0; 0.6; 1.2 phr

X3 Mixland+ DPG 80 GA


= 0; 0.75; 1.5 phr



Curing systems of the 9 recipes WEIGHT DETERMINATION

GRID

CompoundsA B C D E F G H I

Ingredients

NR base 164 164 164 164 164 164 164 164 164

S 80 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5

ZnO 90 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0

TBP 75 3 2 1 1 3 2 2 1 3

CBS 80 0 0 0 0.6 0.6 0.6 1.2 1.2 1.2

DPG 80 0 0.75 1.5 0 0.75 1.5 0 0.75 1.5



The 3 first compound rheometric curves @ 160°C (MDR)T

orqu

e

dN.m

Tor

que

dN

.m

Strong reversion of reference T, low torque of A, B & C; C reverses



The 3 middle compound rheometric curves @ 160°C (MDR)

Tor

que

dN

.m

Higher torque of D, E and F; D reverses



The 3 last compound rheometric curves @ 160°C (MDR)

Tor

que

dN

.m

No reversion for G & I, reversion for H



Compound rheometric data

Compound N°

Ts2 @ 160°C (min)

T 90 @ 160°C (min)

Mx @ Tc50* 160°C

MH-ML(dN.m)

Reversion index

(100+-1.5)

T 1.08 1.33 15 8.65 0.205

A 1.96 5.92 1.33 5.98 0.035

B 1.55 4.2 2.04 5.69 0.035

C 1.37 3.1 2.55 5.01 0.105

D 1.86 3.3 3.8 6.31 0.085

E 1.2 3.12 7.9 8.79 0.025

F 1.41 2.2 8.4 7.43 0.03

G 1.6 2.86 7.52 7.64 0.01

H 1.5 2.28 7.65 5.77 0.3

I 1.19 2.79 10.5 7.9 0.04



0

0.05

0.1

0.15

0.2

0.25

0.3

Rev.index

T A B C D E F G H I

compounds

Reversion index @ 160°C



Mechanical properties 160°C cured sheets.

0

10

20

30

40

50

60

T B F G H

tensile strengthMPa

Delft tear kN/m

Compression set %

MPa&

CS in %

Mechanical property comparison

=> Similar properties, except B, with lower pontal density



=> Variable according to the recipe.

constraint @ 20% MPa

0

0.1

0.2

0.3

0.4

0.5

0.6

T B F G H

compound

co

ns

tra

int

20

% in

MP

a

constraint @ 20% MPa

Mechanical properties, 160°C cured sheets



Next step of the survey

-We carried out cure tests @ 160°C

-We decided to go forward by carying out curing tests at higher temperature: 170°C and 180°C

Possible to maintain mechanical properties?



Next step of the survey

-To clarify the lecture, we focused onto only4 experimental compounds (B, F, G & H) to comparetheir properties @ 160, 170 & 180°C to reference compound T.

Reversion indexSlope @ Tc 50T 90Mh-Ml



00.10.20.30.40.50.60.70.80.9

1R

ev

ind

ex

T B F G H

compound

Reversion index

160°C

170°C

180°C

=> Dramatic reduction of reversion vs higher temperature



0

10

20

30

40S

lop

e

T B F G H

compound

Slope at Tc 50

160°C

170°C

180°C

The rate of curing is lower than TMTD, that makes the compound easier to handle.



0

1

2

3T

90

; m

in

T B F G H

compound

T 90

160°C

170°C

180°C

The cure time @ 180°C is similar to 160°C reference compound cure time.



0

2

4

6

8

10M

h-M

l, d

N.m

T B F G H

compound

Mh-Ml

160°C

170°C

180°C

=> Both 170 & 180 °C torques are similar to reference.



Possible origin of reversion resistance

Lab survey carried out in ARKEMA Research Center of Lacq (France).

Experimental test of cross-linking of TME (2, 3 dimethyl-2-butene) with both TBP and CBS.

How?



Model compound vulcanization (MCV) approach:characterization of possible hybrid bonds

• Model compound used:

• 2,3-dimethyl 2-butene (TME)

CH3

CH3

CH3

CH3

• Experiments:

TBP+CBS

TME 100

ZnO 5

Stearic acid 2

Sulfur 0

CBS 2

TBP 5

• Experimental conditions : cure 30 and 60 min @ 145°C under nitrogen atmosphere



+

OH

S2

OH

R R

Sx (x =1,2,3)

S

R

OH

S

S S

O

R

OH

S

S S

O

R

OH

S2

1

2S

R

OH

S2

S2

R

OH

S2

S

R

OH

S

O

3

3 different mechanisms

detectedby HPLC/MS


Conventional Sulfur bondsHybrid bonds

Sulfoxide bonds

Hypothesis: the hybrid bonds bring reversion resistance.



Hybrid bonds:

Monosulfidic bond

Mono and disulfidic bond

Disulfidic bond

Dissociationenergy:

to be evaluated


Cost effect

*: this overcost could easily be compensated by using higher level of suitable fillers, by the reduction of the time of curing, by an easier handle of a less scorchy compound.

Cost NR baseCuringsystem

Total cost Cost effect

Reference compound

97.3 2.7 100

G compound

97.3 5.4 102.7 + 2.7%*




CONTENTS



2 examples of behavior of both compound T @ 160°C and compound G @180°C

0

12.5

25

reversion

slope Tc 50

T90Mh-Ml

cost T

G



GENERAL CONCLUSIONS

- Improvment of reversion resistance

Comparatively to TMTD, TBP 75, combined with CBS, brings:

- Better curing efficiency at high temperature

-Better scorch safety

-Curing cycle reduction time

- No nitrosamine contamination



thank you for your attention.

38


Thermal stability of crosslinks


Structure Dissociation energy

(kJ/mol)

C-C 335

C-S-C 310

C-S2-C 310

C-S3-C 225

C-Sx-C (x >3) 142


Examples of T90 of the 9 compounds of the design @ 160°C (ref compound T=1.33 min

Reference: TS= 16.7 MPa

0

0.7

5

1.51.2

pce

0.9pce

0.6pce

0.3pce

0 pce

0.00

1.00

2.00

3.00

4.00

5.00

6.00

T 90, min

DPG

CBS

T 90 DPG vs CBS, TBP = 1pce; 160°C5.00-6.00

4.00-5.00

3.00-4.00

2.00-3.00

1.00-2.00

0.00-1.00

0

0.75

1.51.2

pce

0.9pce

0.6pce

0.3pce

0 pce0.00

1.00

2.00

3.00

4.00

5.00

6.00

T 90, min

DPG

CBS

T 90 , DPG vs CBS, TBP = 2pce; 160°C5.00-6.00

4.00-5.00

3.00-4.00

2.00-3.00

1.00-2.00

0.00-1.00

0

0.75

1.51.2

pce

0.9pce

0.6pce

0.3pce

0 pce0.00

1.00

2.00

3.00

4.00

5.00

6.00

T90, min

DPG

CBS

T90, DPG vs CBS, TBP = 3 pce; 160°C5.00-6.00

4.00-5.00

3.00-4.00

2.00-3.00

1.00-2.00

0.00-1.00




Examples of delta torque of the 9 compounds of the design @ 160°C (reference compound T = 8.65 dN.m)

0

0.75

1.51.2

pce

0.9pce

0.6pce

0.3pce

0 pce5.00

6.00

7.00

8.00

9.00

10.00

Mh-Ml, dN.m

DPG

CBS

Mh-Ml, DPG vs CBS, TBP = 3 pce; 160°C9.00-10.00

8.00-9.00

7.00-8.00

6.00-7.00

5.00-6.00

0

0.75

1.51.2

pce

0.9pce

0.6pce

0.3pce

0 pce5.00

6.00

7.00

8.00

9.00

10.00

Mh-Ml, dN.m

DPG

CBS

Mh-Ml, DPG vs CBS, TBP = 2pce; 160°C9.00-10.00

8.00-9.00

7.00-8.00

6.00-7.00

5.00-6.00

0

0.75

1.51.2

pce

0.9pce

0.6pce

0.3pce

0 pce

5.00

6.00

7.00

8.00

9.00

10.00

Mh-Ml, dN.m

DPG

CBS

Mh-Ml, DPG vs CBS, TBP = 1pce; 160°C9.00-10.00

8.00-9.00

7.00-8.00

6.00-7.00

5.00-6.00




0

0.75

1.5

1.2pce

0.9pce

0.6pce

0.3pce

0pce

0.00

0.05

0.10

0.15

Rev index

DPG

CBS

Reversion index DPG vs CBS, TBP = 1pce; 160°C

0.10-0.15

0.05-0.10

0.00-0.05

0

0.75

1.5

1.2pce

0.9pce

0.6pce

0.3pce

0pce

0.00

0.05

0.10

0.15

Rev index

DPG

CBS

Reversion index , DPG vs CBS, TBP = 2pce; 160°C

0.10-0.15

0.05-0.10

0.00-0.05

0

0.75

1.5

1.2pce

0.9pce

0.6pce

0.3pce

0 pce

0.00

0.05

0.10

0.15

Rev index

DPG

CBS

Reversion index , DPG vs CBS, TBP = 3 pce; 160°C

0.10-0.15

0.05-0.10

0.00-0.05

Examples of reversion index response of the 9 compounds of the design at 160°C (reference compound T= 0.205 )


Rubber Division, ACS Fall 2009 Meeting Pittsburgh

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