PILCURE MBT
  • Overview
  • Compounding Information
  • Application
Chemical Name 2-mercaptobenzothiazole (MBT)
Chemical Structure
CAS Reg. No. 149-30-4
Mol. Wt. 167
Product Specification
Parameter Limits Test Method
Product form Powder (OT) -
Color Cream -
Assay (Titration), % (min) 96.0 D 1991
Melting Point (Initial), °C (min) 170.0 D 1519
Melting Point (Final), °C 176-183 D 1519
Heat Loss, % (max) 0.40 D 4571
Ash, % (max) 0.40 D 4574
Paraffinic Oil (<0.2% PCAH), % 1.0-2.0 NOCIL G-40
Residue on 150 µm sieve, % (max) 0.05 D 5461
Residue on 63 µm sieve, % (max) 0.50 D 5461
Typical Data
Specific gravity at  25°C 1.51 D 1817
Bulk density, kg/m3 400 - 440 NOCIL G-44
Bulk density (Comp), kg/m3 580 - 620 NOCIL G-44
Product Information
Solubility Soluble in acetone, chloroform and dilute alkali. Slightly soluble in alcohol. Insoluble in water and gasoline.
Classification Semi ultra fast accelerator.
Discoloration & Staining Non-discoloring and Non-staining.
FDA Approval Status Regulated for use in articles in contact with food under FDA 21 CFR 177.2600, 175.105, 176.300 and BgVV XXI categories 1-4 & ‘Sonderkategorie’.
Toxicity Data
(Please refer to the latest
 Toxicological information.)
 Practically non-harmful. (Oral LD50rat over 5000 mg/kg). Not a skin or eye irritant.
Handling & Personal Protection Ensure good ventilation and avoid creating dusty atmosphere. In case of eye or skin contacts wash out with clean water for 5 to 10 minutes.
Storage Store at room temperature in a cool, dry and well ventilated place. Avoid exposure of the packaged material / product to direct sunlight & heat.
Packaging
Paper-Fabric  Bag 20 kg
FIBC 500 kg
Storage Life 24 months
Color code Blue colored strip.

Pilcure MBT is a semi ultra fast accelerator for NR, SBR, BR, NBR and other highly unsaturated diene rubbers. It readily disperses in rubber compounds and also acts as a mild peptizer for NR & CR. Pilcure MBT is a re-tarder of cure in rubber compounds accelerated using thiurams (TMTD/TMTM) / dithiocarbamates (ZDC, ZDBC) or ETU class accelerators as main accelerators. Even relatively small dosages of Pilcure MBT show significant effect and reduce bloom of thiurams and dithiocarbamates. Pilcure MBT also acts as a retarder in CR based compounding formulations.

Pilcure MBT has a long curing range and is very active above 115°C. Pilcure MBT gives flat curing characteris-tics for 'polyisoprene' rubber (e.g. NR) based compounds exhibiting ability to withstand long over cures. However, MBT accelerator is scorchy in nature and the rate and the state of cure achieved is comparatively lower than sulphenamide accelerators like CBS & TBBS. Thus, when used alone, Pilcure MBT exhibits comparatively lower tensile properties and resilience. However, in combination with other accelerators marked improvements are observed.

Normal dosages of Zinc oxide and Stearic acid are necessary as cure activators for Pilcure MBT based sulphur cure systems. Pilcure MBT when used alone shows poor response to low sulphur cure systems. However; in combination with other basic accelerators like TMTM, TMTD very low, medium or high sulphur cure systems can be designed.

Pilcure MBT based cure systems can be activated by using small proportions of basic accelerators like DOTG, DPG, TMTM, TMTD, ZDC etc. to improve the rate and the state of cure with a compromise on scorch, reversion and ageing resistance particularly when dithiocarbamate type accelerators are used as booster accelerators.

Pilcure MBT based cure systems can be retarded by using small proportions of Pilgard PVI, or other retarder like pthalic anhydride, salicylic acid, etc. Addition of extra Stearic acid or partial replacement of MBT accelerator by sulphenamide accelerator can also control scorch to some extent.

In case of low unsaturation content rubbers (e.g. IIR / EPDM) cured with thiurams and dithiocarbamate accelerators ; Pilcure MBT acts as a retarder. In EPDM based rubber compounds the dosage of Pilcure MBT is kept below 2.5 - 3.0 phr to avoid bloom of dithiocarbamate / thiurams type accelerators. Pilcure MBT is generally avoided in carbon black filled halogenated butyl rubber based stocks due to its scorching tendency; however, the same can be used in light colored Chlorobutyl based compounds for faster cure.

Pilcure MBT itself does not discolor white /colored vulcanizates, however; slight yellowing effect is observed when white colored products are exposed to sunlight. The effect of Pilcure MBT on colored products is very minimal. Pilcure MBT and other thiazole class accelerators are particularly preferred for rubber to metal bond-ing applications due to the absence of any free amines.

Pilcure MBT and its combinations with booster accelerators is extensively used in NR,SBR, NR-SBR/BR blends, NBR, IIR,EPDM and other synthetic rubber based compounds used for the manufacture of motor cycle and scooter tyres, butyl tubes, cycle tyres and tubes, beltings, retreading materials, footwear, hot air cured products, hoses, cables and miscellaneous molded and extruded rubber products.

TYPICAL DOSAGES OF PILCURE  MBT
Product Rubber Accelerator /  Sulphur, phr
MBT MBTS MOR TMTD ZDEC S
Motor Cycle, Scooter
Tyre Treads
NR-
SBR / BR
0.8-1.0** - - 0.07-0.15 - 2.2-2.75*
Auto Tubes IIR 0.5 - - 1.0 0.0-0.2 1.5
Cycle Tyre Treads NR-RR
NR-SBR / BR
0.6**
0.8**
0.3
0.4
- 0.1-0.15
0.1-0.2
- 2.2-2.5
2.2
Conveyor Belt Cover NR
SBR
0.70**
1.0**
0.25
0.4
- 0.0-0.15
0.0-0.20
- 2.75*
2.2
Transmission Belts
General Purpose
Heat Resistant
  NR
NR
  0.3
0.5
-   0.8
-
  -
2.0-2.5
-   3.0
0.3
V Belts
Base
Cushion
  NR
NR
  0.2
0.4
-   0.6**
0.6**
- -   3.0
2.4
Retreading Materials
Cushion-Hot Cure
Cushion-Cold Cure
Vulcanizing Solution
  NR
NR
NR
  0.2
1.0
0.6
  -
-
0.4
  0.7**
-
-
  -
TMTM-0.2
-
-   2.4*
2.4*
4.0*
Footwear
DV Soles
Microcellular Soles
Neolite Soles
  NR-SBR
NR-SBR
NR-SBR
  0.8
1.0
1.0
- -   0.2-0.3
0.1-0.2
0.1-0.2
-   2.0
2.3
2.5
Hot Air Cured Products
Rubberized Fabric and
Rubber Sheeting
NR 0.8 - - - 0.3-0.4 2.5
Cables NR
SBR
1.0
1.5
- - TMTM
0.2-0.3
- 1.2
1.0
Misc. Molded and
Extruded Products
NR
SBR
NBR
0.8-1.0
1.2-1.5
1.2-1.5
- - 0.0-0.2 - 2.4
2.2
1.5
Note:
* Insoluble Sulphur (100% active content basis)
** Pre Vulcanization Inhibitor may be incorporated at 0.2-0.5 phr levels for desired
scorch safety, ensuring compliance with vulcanizate properties.

 

PILCURE MBT based Cure Systems for sulphur cured EPDM Products
Accelerator
& Sulphur
Cure Systems (phr)
A B C D E
MBT 0.5 1.5 1.5 2.0 1.5
TMT 1.5 0.8 1.0 0.8 0.8
ZDC - - - 0.8 -
ZDBC - 2.5 2.5 1.0 -
CBS - - 1.0 - -
TeDEDC - - 1.0 - 0.8
DPTTS - - - - 0.8
Sulphur 1.5 2.0 1.8 2.0 0.5
Cure System Characteristics
A Low cost, Medium cure rate, Satisfactory vulcanizate properties, may bloom.
B General purpose, Very good cure rate and vulcanizate properties, Non-blooming.
C Low compression set, Faster cure rate, Good vulcanizate properties, Non-blooming.
D Low cost, faster cure rate, Good vulcanizate properties, Non-blooming.
E General purpose, Very fast cure rate and excellent vulcanizate properties, Non-blooming but scorchy.