PILCURE NS
  • Overview
  • Compounding Information
  • Application

 

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 tow 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. 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 observed 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)