Hot melt adhesives can be used within the following applications:

• Submarine, land and aerial cables
• Ribbon encapsulation
• Water blocking
• Interlayer bonding and strengthening
• End capping
• Kevlar bonding
• Shrink sleeve tubing (the heat reaction layer)

Specialist requirements include:

• Low temperature flexibility - must withstand end use conditions of -60°C
• High adhesion
• Low peel adhesion
• No elastic memory
• Heat resistance - must withstand end use conditions of +80°C
• Water resistance and blocking

Beardow Adams works with major international cable manufacturers with hot melt adhesives as a critical part of their cable designs.  Some examples are given below:

Water blocking a submarine cable

For a submarine cable application, a 12 mm thick, high density polyethylene (PE) cable jacketing is bonded to a high tensile steel inner core to ensure that there is no movement between the core and the outer protective sheath of the cable. The quality of the bond is critical, as no interlayer slip can be tolerated during the laying or recovery operations at cable tensions of up to 8 tonnes. This particular hot melt has excellent adhesion to metal, PE and most other plastics. It acts as a water blocker in the submarine cable systems as well as being inert ensuring against hydrogen generation. The adhesive has been tested through a temperature range of -50°C to +80°C and has an open time to match process line requirements for even coating. It can be used with PE extrusion processes to be reactivated to form a bond after initial application.

Recabling Germany

Another hot melt adhesive, with low peel strength but high dynamic shear, was developed for use in  the construction of the land cables that are part of the massive recabling of Germany's entire telephone system. The adhesive has exceptionally good water blocking capabilities. Its low peel strength allows the PE outer sheath to be pulled back when splicing. Using kevlar impregnated with hot melt, for a suspended air cable, hot melt is pre-coated on to kevlar to protect the inner fibre optics. It is reactivated as the layers of hot melt and kevlar are built up and then bonded to the outer sleeve to provide a secure, water blocked cable.

Shrink sleeve tubing

For shrink sleeve tubing applications, hot melt is coextruded on to the inside of the PE tubing that is used to cover and protect cable repairs. The key requirements for the hot melt are that:

• It should maintain flexibility, even at temperatures as low as -50°C.
• It should adhere strongly to the PE.
• It should act as an additional water barrier.
• It should have no residual set tack so that the tubing is easy to slide into position.

After the hot melt has been applied, the tubing is irradiated to cure the PE, without affecting the hot melt. The bond is formed by heat reactivation to seal the cable joints


Which adhesive?

Contact us or your local distributor to identify the adhesive grade best suited to your application requirements. Find your local distributor on our 'Global Network' pages.