Formulated silane is also called as silane cocktail; it is a multi-component silane formulation suitable for the manufacturing of low and medium voltage cross-linked polyethylene cable insulation & jacket, PEX-b pipe or other XLPE products.
With these easy-to-dose liquid products we offer tailor-made blends consisting of all necessary ingredients for grafting and crosslinking of polyethylene resulting in XLPE or PEX-b compounds. These products contain vinyl silanes and initiators for the two-step SIOPLAS® process, and additionally crosslinking catalysts plus if needed other additives, e.g. antioxidants, metal deactivators, processing aids for the one-step Monosil® process.
Ingredient
Function
Vinyl Silane
Crosslinking agent; always it is a basic ingredient of the dry silane.
Peroxide
Initiator; always it is a basic ingredient of the dry silane.
Catalyst
Accelerate the reaction speed of hydrolysis and crosslinking rate; always it is a basic ingredient of the dry silane.
Antioxidant
Stabilize PE resin during extruding and long turn working, should be used in unstabilized PE resins.
Metal Deactivator
Inhibit the catalytic effects of metal ions especially copper, should be used cooper cables.
Other ingredients like UV inhibitor could be added under the customer’s request.
Formulated silane has dozens of different grades to meet different PE resin type, differne conductor type and different process like one-step Monosil, two-step Sioplas, Spherisil and dry silane process. Basically the user will spay the formulated silane and mix it with the virgin PE pellet, and then feed this silane coated PE into extruder. Another way to use formulated silane is just to use a liquid pump to inject it into the extruder; this method is very common in one-step Monosil process.
During the extrusion phase the liquid silane cocktail which contains vinyl silane, peroxide, tin catalyst, antioxidant and metal deactivator will chemically react; their basic chemical mechanism is same to the regular PEX-b process:
At first grafting stage, vinylalkoxysilane is grafted via its vinyl groups on polyethylene through a peroxide initiated free radical reaction. After the grafting, polyethylene can still be processed as a thermoplastic resin like regular PE resin as it has not cross-linked. Only this grafted polyethylene treated with moisture like hot water bath (65~100℃), steam bath or even at ambient the grafted vinylalkoxysilane will hydrolyze and condensed, thus the polyethylene will final be cross-linked.
Polyethylene is a volume leader in the global plastic industry with numerous applications. However, its low upper service temperature makes ordinary polyethylene unsuitable for the applications requiring continuously continuous use under stresses at temperatures up to 100℃ (for example in hot water pipes) or occasional increases in temperature above a certain limit during temporary electrical overloads on cables. By cross-linking of polyethylene some important properties would be drastically improved (Table 1). Some applications include heat shrinkable products (in cable installation), heat-resistant foodstuff packaging (up to 200℃), foams for thermal insulation, and chemical-resistant seals. Moreover, cross-linked polyethylene is more resistant to water treeing and tracking which are undesirable in cable insulation & jacketing industry. Besides the capability of cross-linked polyethylene in withstanding higher electric loading, its ability to tolerate thermal shocks, and the small thickness required for insulation, makes it a suitable candidate for cable insulation & jacketing industry. Polyethylene has the melting point of 100~130℃, however, after cross-linking no flow would be noticed even at 150℃ where elastic behavior prevails.
Property of PE resin
Property change of PE resin after crosslinking
Melt Index
Decrease
Density
No changes/ slightly decrease
Molecular Weight
Significantly increased
Tensile Strength
No changes/slightly increase
Elongation-at-break
Decrease
Impact resistance
Significantly improved
Abrasion resistance
Greatly improved
Stress-crack resistance
Greatly improved
Elastic properties
Greatly improved
Environmental stress crack resistance
Increase
Resistance to slow crack growth
Increase
Temperature resistance
Greatly improved
Chemical resistance
Significantly increased
Main applications of silane crosslinking polyolefin are as below:
1. Wire and Cables (insulation & jacketing layer for LV and MV)
2. Pipes (hot water, underfloor, gas, chemicals, sewage)
3. Heat Shrinkable products (tubes, sleeves)
4. Films (creep resistance and shrinkable applications)
5. Foams (heat insulation)
6. ……
Formulated silane is a ready-to-use, multi-components silane formulation; it is a user-friendly and simple way to produce XLPE wire & cable and PEX-b pipe.
Our formulated silane products are mainly used for XLPE wire & cable and PEX-b pipe, those masterbatches contains up to 5 different ingredients:
Ingredient
Function
Vinyl Silane
Crosslinking agent; always it is a basic ingredient of the dry silane.
Peroxide
Initiator; always it is a basic ingredient of the dry silane.
Catalyst
Accelerate the reaction speed of hydrolysis and crosslinking rate; always it is a basic ingredient of the dry silane.
Antioxidant
Stabilize PE resin during extruding and long turn working, should be used in unstabilized PE resins.
Metal Deactivator
Inhibit the catalytic effects of metal ions especially copper, should be used cooper cables.
Other ingredients like UV inhibitor could be added under the customer’s request.
According to different application, different resins & conductors type we develop several different dry silane formula to meet the market demands. They contain different ingredients and have their own features. Our SLC series is suitable for Monosil one-step process and SLX series is designed for Sioplas two-step process.
Grade
Dosing
Application & Performance
SCA-V71M
1.0~2.2 %
SCA-V71M is a high-purity vinyltrimethoxysilane.
SLX-604
1.0~2.2 %
SLX-604 is designed for pipe application. It contains a special processing aid and has to be blended with suitable peroxide prior to processing.
SLX-911
1.2~2.2 %
SLX-911 is a VS system for pipe application (PEX-b). All ingredients of it are regulated according to “plastic to come in food contact”.
SLX-924
1.2~2.0 %
SLX-924 is a fully VS system for non-stabilized resins. It is designed for LV/MV cables on Al conductor or conductor screen MV power cables. It is designed to meet the ageing test 10 days @ 150℃.
SLX- 890
1.2~2.0 %
SLX-890/1 is a fully formulated VS system for non-stabilized resins. Designed for LV/MV cables with copper conductor. It is designed to meet the ageing test 7 days @135℃.
Briefly we could use the following decision tree to help you to choose the right SLX formulated silane for your Sioplas process.
On the contrary, SLC series formulated silane has more grades.
Grade
Resin
Dosing
Application, Features & Benefits
SLC-17
All PE types
0.8~1.8 %
SLC-17 is a general use SLC system. Peroxide and antioxidants have to be added prior to processing.
SLC-R
LDPE / LLDPE
0.8~1.8 %
SLC-R is a general use SLC system for stabilized LDPE and LLDPE resins.
SLC-RHE
MDPE / LLDPE
0.8~1.8 %
SLC-RHE is a highly efficient system specially designed for LLDPE, MDPE & HDPE resins. SLC-RHE provides enhanced grafting efficiency, faster curing, reduced scorch in comparison to SLC-R. SLC-RHE contains low odor peroxide.
SLC-RHS
LDPE / LLDPE
0.8~1.8 %
SLC-RHS is a general use system for stabilized LDPE and LLDPE resins. It provides in particular high stability during storage and handling in warmer climates, while maintaining the reactivity of SLC-R.
SLC-963
LDPE / LLDPE
1.5~2.0%
SLC-963 silane is a fully formulated system for LV/MV Cu/Al cables. SLC-963 is designed to meet the ageing test 7 days @135 ℃ on copper or 10 days @150 ℃ on aluminum wire.
SLC-735
LDPE / LLDPE
1.3~2.0%
SLC-735 silane is a fully formulated system for LV/MV copper cables. SLC-735/1 is designed to meet the ageing test 10 days @135℃ on copper or 10days @150 ℃ on aluminum wire.
SLC-928
LDPE / ULDPE
1.2~2.0%
SLC-928 silane is a fully formulated system for LV/MV copper cables. SLC-735/1 is designed to meet the ageing test 10 days @135 ℃ on copper or 10days @150 ℃ on aluminum wire.
SLC-966
LDPE / LLDPE
1.6~2.2%
SLC-966 is a highly stabilized system for low voltage copper cables. It is designed to meet the ageing test 7 days @150 ℃.(e.g. G7 specification).
SLC-758
HDPE / MDPE
1.5~2.2%
SLC-758 is a VS system designed for pipe applications (PEX-b). All ingredients of SLC-758 are regulated according to standards” plastic to come in food contact”. Depending on the base resin and additional stabilizer package might be required for processing.
SLC-870
N.A
1~2%
SLC-870 is a fully formulated VS system designed for crosslinking of halogen-free flame retardant and semi-conductive compounds containing carbon black.
Accordingly we recommend the decision tree as below to find out the right SLC grade for Monosil one-step process.
