Pilcure ZDC is a widely used ultra fast accelerator for NR latex based compounds and also finds applications as primary or secondary accelerator in most dry rubber based sulphur cured compounds.
Pilcure ZDC is very active at temperatures above 100°C. As a primary accelerator in NR dry rubber based compounds. Pilcure ZDC exhibits scorching tendency, faster cure rate, higher cross link density but poor reversion resistance. However; Pilcure ZDC does not affect the stability of NR latex based compounds.
Normal dosages of Zinc oxide and Stearic acid are necessary as cure activators for Pilcure ZDC based cure systems designed for diene rubbers. Pilcure ZDC disperses well in latex / dry rubber based compounds and does not decompose in the absence of sulphur. It may be noted that the vulcanizates cured with all types of dithiocarbamate accelerators may exhibit poor ageing properties in the absence of antioxidants / antidegradants.
Low unsaturation content rubbers such as Butyl rubber and EPDM can be cured using Pilcure ZDC as a secondary accelerator at relatively higher dosage along with Thiuram class primary accelerators. The thiazole class accelerators act as cure rate modifiers in such compounds.
Highly basic accelerators / amines further activate the cure rate of Pilcure ZDC based cure systems which are used for the manufacture of self curing adhesives. However, in dry rubber compounds Pilcure ZDC is mainly used as a booster accelerator and offers typical synergistic effect with thiazole class accelerators. In case of sulphenamide based cure systems, Pilcure ZDC is a very active booster accelerator and even very small dosages are highly responsive. Accelerators such as Pilcure MBTS, Pilcure TMT at 0.05 - 0.1phr dosages act as retarders where Pilcure ZDC is used as primary accelerator.
Pilcure ZDC has a limited solubility in rubber compounds and hence excess quantity of Pilcure ZDC tends to bloom on the surface of the vulcanizate. (The ‘bloom’ of thiuram class accelerators is accelerator ZDC itself, since thiuram accelerator is converted to ZDMC during the vulcanization in the presence of Zinc oxide.)
Pilcure ZDC is non- staining and non-discoloring even on exposure to light and is suitable for the manufacture of transparent goods; however, Pilcure ZDBC is the most preferred accelerator for this purpose. Vulcanizates based on Pilcure ZDC / Pilcure TMT can be used for food contact applications subject to a maximum 1.2% by weight of the finished product. (It may be noted that FDA Rules & Regulations are subject to change and seeking clarifications from relevant authorities is recommended before commercial manufacture of rubber products).
Recommended method for preparation of 50% dispersion of Pilcure ZDC for latex compounding is given below :
Ingredients |
Dry
|
Wet
|
|
Pilcure ZDC, pbw
|
50
|
50
|
|
10% Dispersing Agent *, pbw
|
1.0
|
10
|
|
10% KOH Solution, pbw
|
0.5
|
5
|
|
China Clay, pbw
|
0.5
|
0.5
|
|
Water, pbw
|
-
|
34.5
|
|
Total
|
52
|
100
|
|
* Sodium salt of polymerized alkyl naphthalene sulfonic acid type.
|
METHOD:
Charge Pilcure ZDC, dispersing agent and part quantity of water and grind to paste. Add china clay, balance quantity of water , 10% KOH solution and ball mill for 24 to 48 hr.depending on the requirements of the rubber product to be manufactured
LATEX COMPOUNDING:
Pilcure ZDC is widely used for the manufacture of NR/SR latex based products such as Latex Foam, Coir Foam, Latex Threads, Latex Tubings, Prevulcanized lattices, Surgical Gloves, Household and Industrial gloves, Condoms, Teats, Toy balloons, Rubber bands, Carpet backings, Latex adhesives, etc.
DRY RUBBER COMPOUNDING:
Pilcure ZDC alone is used in the manufacture of white / colored rubber products such as Footwear components, Seals, Gaskets, Bathing caps, Hoses, Beltings, Cut threads, Sponges, Expanded rubbers, Rubberized fabrics, Rubber Sheeting, Stereo rubbers, Food contact applications, etc.
TYPICAL DOSAGES:
Typical dosages of Pilcure ZDC used in latex compounding, please refer the table given for Pilcure ZMBT. Additional applications of Pilcure ZDC in latex compounding as well as in dry rubber compounding are given below. (Accelerator and Sulphur dosages are on ‘dry’ basis).
|
TYPICAL DOSAGES OF PILCURE ZDC
|
|
Product
|
Rubber
|
Accelerator / Sulphur, phr
|
|
ZDC
|
ZMBT
|
MBT
|
TMTD
|
CBS
|
S
|
|
Latex Products :
|
|
Surgical Gloves
Electrician’s Gloves
Household Gloves
Latex Foam
Coir Foam
Latex Thread
Misc. dipped goods
Latex Adhesives
Carpet backings
Toy Balloons
|
NR Latex
|
0.7
1.5
1.0
1.0
1.0
0.5
1.0
1.0
1.5
0.6
|
0.2
-
-
1.0
1.0
1.0
0.2
-
1.5
-
|
-
-
-
-
-
-
-
-
-
-
|
-
-
-
-
-
-
-
-
-
-
|
-
-
-
-
-
-
-
-
-
-
|
1.0
1.25
1.25
2.0
2.0
1.8
1.0-1.2
-
2.0
0.7
|
|
PV Lattices :
Low Modulus
Medium Modulus
High Modulus
|
NR Latex
|
0.25
0.5
1.0
|
-
-
-
|
-
-
-
|
-
-
-
|
-
-
-
|
0.25
1.0
2.0
|
|
Cast Products
|
NR Latex
|
1.0-1.5
|
-
|
-
|
-
|
-
|
1.5-2.5
|
|
Latex Tubing
|
NR Latex
|
1.2
|
0.2
|
-
|
-
|
-
|
1.0
|
|
Dry Rubber Products:
|
|
Food Applications
|
NR
SBR
|
0.3
0.5
|
-
-
|
-
-
|
0.1
0.2
|
-
-
|
2.0
1.5
|
|
Colored Molded Products
|
NR
SBR
|
0.5
0.7
|
0.2
0.3
|
-
-
|
-
-
|
-
-
|
2.0
1.7
|
|
Molded & Extruded
Products
|
EPDM
BUTYL
|
0.75
0.5-1.0
|
-
-
|
0.5
0.5
|
1.5
1.5-2.0
|
-
-
|
1.5
2.0
|
|
Cables
|
NR, SBR
|
1.0
|
-
|
0.7
|
-
|
0.7
|
1.0
|
|
Hot Air Cured Products
|
NR, SBR
|
0.7
|
-
|
0.5
|
-
|
-
|
1.5
|
|
Steam Cured Products
|
NR, SBR
|
0.15
|
-
|
-
|
-
|
1.0
|
1.25
|
|
Stereo Rubbers
|
NR
|
0.25
|
-
|
-
|
-
|
1.5
|
1.5
|
|
Sponge Rubber
|
NR
|
1.0
|
-
|
0.25
|
-
|
-
|
1.2
|
|
LCM Cured Products
|
NR
|
0.4
|
-
|
0.20
|
-
|
1.5
|
1.2
|
|
NR-EPDM Blends(80:20)
|
NR-EPDM
|
0.6
|
-
|
1.7
|
-
|
-
|
1.8
|