PILCURE NS
  • Overview
  • Compounding Information
  • Application
Chemical Name N-butyl - benzothiazole sulfenamide. (TBBS)
Chemical Structure
CAS Reg. No. 95-31-8
Mol. Wt. 238
Product Specification
Parameter Limits Test Method
Product form Pellets (2 mm ) Powder (OT) -
Color Off White to tan Off White to tan -
Assay (titration ), % (min) 96.0 95.0 D 4936
Melting Point, initial, °C (min) 104.0 103.0 D 1519
Melting point, final , °C 106-112 105-112 D 1519
Heat Loss, % (max) 0.4 0.4 D 4571
Methanol Insolubles , % (max) 0.4 0.4 D 4934
Free Amine, % (max) 0.4 0.4 D 4936
Ash, % (max) 0.4 0.4 D 4574
Paraffinic Oil (<0.2% PCAH), % Not applicable 1.0-2.0 NOCIL 02-3-343
Residue on 150 µm sieve, % (max) Not applicable 0.0 D 5461
Residue on 63 µm sieve, % (max) Not applicable 0.5 D 5461
Typical Data
Specific gravity at 25°C 1.28 D 1817
Bulk density , kg/m3 320 – 360 360 - 400 NOCIL G-44
Bulk density (Comp), kg/m3 390 – 430 460 - 500 NOCIL G-44
Product Information
Solubility Soluble in acetone, benzene, naptha, carbon  tetrachloride & ethyl acetate. Partially soluble in ethyl / methyl alcohol. Insoluble in water.
Classification Fast – Delayed action accelerator.
Discoloration & Staining Non-staining. At higher dosages slight discoloration.
FDA Approval Status Regulated for use in articles in contact with food under FDA 21 CFR 177.2600, and BgVV  XXI, Category 4.
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 Always store in a cool (below 30ºC) & dry place in single stack pallets away from direct sun light or any other heat source to avoid compaction. Avoid exposure to acids, acidic materials / atmosphere & high humidity.
Packaging
Paper-Fabric Bag 20 kg
FIBC 500 kg
Storage Life 12 months when stored as stated above.
Color code Dark Brown colored strip.

Pilcure NS is a delayed action sulphenamide accelerator for NR, SBR, BR, NBR and other sulphur / sulphur donor cured diene rubbers. Pilcure NS exhibits very good storage stability as compared to other sulphenamide accelerators and Pilcure NS pellets disperse easily in rubber compounds.

The normal dosage of Pilcure NS is in the range of 0.5-1.0 phr for 'conventional cure systems; 1.5-2.0 phr for 'Semi-EV' cure systems and 3.0-4.0 phr for 'Low sulphur EV cure systems'. Normal dosages of zinc oxide and Stearic acid are necessary for cure activation.

Pilcure NS is very active above 140°C, and it offers better scorch safety as compared to Pilcure CBS. When used alone, Pilcure NS exhibits faster cure rate above 160°C which is almost similar to Pilcure CBS; however, the state of cure achieved with Pilcure NS is approx. 10% higher (but lower than thiazole accelerators). To minimize the risk of scorch, prolonged / repeated rubber stock processing over 125°C should be avoided in the absence of appropriate dosage of Pilgard PVI. The synthetic rubber based vulcanizates accelerated with\Pilcure NS cure exhibit higher modulus, tensile strength, resilience and elastic properties as compared to other sulphenamide accelerators.

Like other sulphenamide accelerators; Pilcure NS is usually incorporated in the rubber compound at the end of mixing cycle when the stock temperature is above the melting point of Pilcure NS. In case, Pilcure NS is to be added at a later stage; addition in the form of Pilcure NS-Rubber master batch prepared above its melting point is recommended to ensure proper dispersion and dissolution of the accelerator.

Pilcure NS based cure system can be further activated by using small proportions of thiuram or dithiocarbamate accelerators; however, thiurams (TMTM, TMTD) are preferred. Activation using thiurams or dithiocarbamates is associated with a compromise of processing safety, reversion resistance and ageing resistance. Use of DPG / DOTG as secondary accelerators is generally avoided. Pilgard PVI is highly effective pre vulcanization inhibitor for Pilcure NS based cures and exhibits around 10% better response to Pilcure NS as compared to Pilcure CBS. The improvement in scorch safety is in linear proportion to the dosage of Pilgard PVI used and thus exact dosage of Pilgard PVI required for obtaining desired increase in the processing safety can be easily determined. Use of excessive dosage of Pilgard PVI is avoided.

Like other sulphenamide accelerators, Pilcure NS also decomposes rapidly in the presence of hot steam and hence preferred for the manufacture of open steam cured rubber products requiring faster onset of cure. However, due to delayed onset of cure; sulphenamide accelerators are not preferred in hot air cured products in the absence of strong secondary accelerators.

Pilcure NS is itself non-staining. However, when higher dosages are used slight yellowing effect may be ob-served on white / light colored rubber products on exposure to sun light.

Pilcure NS alone or in combination with small quantities of booster accelerators is widely used in NR, SBR, NR/BR/SBR blend, NBR and other synthetic rubber based compounds used for the manufacture of auto tyre treads, sidewalls, casings, cycle tyres & tubes, conveyor & V-belts, tyre retreading & repair materials, footwear, hoses, cables, injection molded products and various compression / transfer molded as well as extruded rubber goods.

TYPICAL DOSAGES OF PILCURE NS
Product Rubber Accelerator /  Sulphur, phr
TBBS MBTS TMTD TMTM PVI (CTP) S
Auto Tyres
Treads   Casing
  NR
NR-BR
SBR-BR
NR-SBR
NR
NR-SBR
NR-BR
0.4-0.6
1.2
1.25
0.75
0.6-0.7
0.9
1.0
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0-0.2
0-0.2
0-0.1
0-0.2
0-0.2
0-0.1
0.10-0.15
0.12
0.10-0.15
0.10-0.15
0.10-0.15
0.10-0.15
0.10-0.15
2.4*
1.6*
1.6*
2.0*
2.4*
2.2*
2.2*
Cycle Tyre
Treads
NR-RR
NR-SR
0.8
1.1
-
-
0.1-0.15
0.1-0.15
-
-
0.1-0.15
0.1-0.15
2.4
2.0
Conveyor Belt Cover
General Purpose Heat Resistant
NR
NR-SBR
NR-SBR
 0.6
1.2
1.4
0.2
-
-
-
-
0.5
-
-
-
0.12
0.12
0.20
2.4
1.75
0.50
Transmission Belts NR 0.7 - 0.1 - 0.15 3.0
V Belts
Base
Cushion
Friction
NR
NR
NR
0.5
0.6
0.7
0.2
0.1
-
-
-
-
-
-
-
0.15
0.12
0.10
3.0
2.4
2.75
Retreads (Truck Tyres)
Hot Cure Pre Cured
Cushion- Hot Cure
NR
NR-BR
NR-BR
NR
0.5
0.8
0.8
0.6
-
-
0.3
-
-
-
-
-
-
-
-
-
0.15
0.12
0.10
0.12
2.4*
1.7*
1.6
2.5*
Footwear
DV Soles
Molded Soles & Heels
NR-SBR
NR-SBR
0.9
0.9
0.3
-
0.1
0.2
-
-
0.10
0.10
2.0
2.2
Hoses
Tube   Cover
NR
NR-SR
NBR
NBR
NR
0.8
1.1
1.3
0.7
0.7
-
-
-
-
-
0.10
0.20
0.50
0.10
0.05
-
-
-
-
-
0.10
0.10
0.10
0.15
0.15
2.2
1.5
0.7
1.8
2.2
Cables NR 1.0 - 0.20 ZDC-0.2 0.15 2.0
Injection Moldings NR 0.5 - - - 0.30 2.4
Molded & Extruded Goods NR
NR-SeEV
NR-EV
SBR
SBR-SeEV
SBR-EV
NBR
NBR-SeEV
NBR-EV
0.6
1.5
3.0
1.0
2.0
1.5
1.0
1.0
2.0
-
-
-
-
-
-
-
-
-
0.15
0.50
-
0.20
0.50
3.0
0.15
1.0
3.0
-
-
-
-
-
-
-
-
-
0.10
0.10
-
0.10
0.10
0.20
0.10
-
-
2.2
1.4
0.5
2.2
0.75
0.30
1.50
1.0
0.3
Note: * Insoluble Sulphur (100% active content basis)