It mainly depends upon the end application you would be looking at, but i would begin with acrylic resins as the starting points.

Quick curing epoxy system is another route you might want to try.,if your system is not a thin film (100 microns )system

Ankur Shah, thank you!

Acrylic resins is a good idea. As for epoxy systems: we have tried it. But there was no connection with PE. And yes, we have to glue 2 thin films (150 micron)

Fedor, you could also look into low viscous epoxy system, where its become near Newtonian at 45-50 C. then you would be able to just brush a very thin coat of the adhesive and bin the films together.

Also using the same principle you can dip coat on film and cover it with clean films giving you 3 layer sandwich system. Press them using lubricated (release agent coated) dies to push out the excess adhesive and you will get a uniformly thick layer of adhesive.

Another aspect, if you have the facility to use spray coating system, is to spray the adhesive. Many nozzles would give you droplets in the mist region which would again no compromise the thickness of the adhesive you would want to apply.

My suggestion are based on the assumption that 40-60 C of working temperature is not considered high temperature processing

Heat sealing is the best method for joining the PE film.

PE is the lowest surface tension material . Directly no adhesive will work.

Other wise you have to go for surface treatment like corona discharge or flame treatment to improve the surface tension. Adhesive also effects the flexibility the film. So heat sealing is the best method

Dear Ankur Shah and M. Kannan, thank you very much!

You can get a much better wetting and bonding if you use a plasma or corona treatment. I have recently tried a small handheld device that perfectly worked: PZ2 from relyon plasma see http://www.relyon-plasma.com/en/products/cold-active-plasma-systems-pz2.html

First surface energy of PE once extruded is around 33 dyne/cm2. Not much will adhere to it. You need to improve the surface polarity ( corona or flame) to raise to above 38 ( 42-44 better)

Most adhesives have surface tension of around 28 dynes/cm2. At least 10 units surface energy to surface tension , is required for proper wetting that is why you must corona/flame  treat to at least 38 dyne/.

Once both surfaces are treated ( make sure they have no slip or PA additives), you can bond them with many adhesives and standard processes ( gravure etc) You must work with excellent tension control as PE has a relatively low tensile yield and high elongation at yield

Also you can extrusion weld, both film polar layers facing each then extrude PE and squeeze the films together 

Dear Ricardo,

thank you very much for the detailed answer!

You are welcome. Most common way to "glue" nowadays in conventional coater dryer system is water base acrylic type adhesives with anilox roll ( gravure) and smooth roll urethanes via single( moisture curable) or 2 component. (Cyanate+polyol).

A machine for laminating (glueing) will help you study, see below http://www.nordmeccanica.com/en/combi_solutions/combi_range.php