With wet laminations, the adhesive is applied to one substrate, usually by roller coating or air knife. The coated substrate is then nipped with another substrate, and the resulting laminate may then be left to air dry or passed through a heated oven to remove solvent and build bond strength. The types of adhesive used for wet lamination are:
waterborne natural products, such as starch and dextrin or
waterborne synthetic latex products, such as polyvinyl acetate, acrylic, etc.
100% reactive liquids, such as polyurethanes or polyesters.
Wet lamination via waterborne or solvent based adhesives is confined to applications where at least one substrate is porous (e.g., paper, cardboard, textiles) to facilitate drying. Once cured, bond strength is generally high enough to cause failure or tearing of the porous substrate. Most often, waterborne synthetic latex adhesives are utilized for wet bonding because of their high initial strength and fast drying characteristics when applied to porous substrates.
Dry laminations are those in which the liquid adhesive is first dried before lamination. The adhesive can be either applied to one substrate and dried or it can be applied as a hot melt type of film (essentially another film layer). The adhesive is then in the dry solid or slightly tacky stage when joined with the other substrate. The bonding is generally achieved during a high temperature, high pressure nip. The temperature and pressure are sufficient to cause the adhesive to flow and create an instantaneous bond when it cools and gels. Dry lamination can be applied to a broader range of products such as film-to-film and film-to-foil.
Dry laminating adhesives are generally solvent based although considerable development has taken place to reduce or replace the solvent to meet environmental regulations. This has produced several strong competitors to conventional solvent-based adhesives such as:
hot melts (e.g., ethylene vinyl acetate copolymers),
100% reactive solids (e.g., two-part polyurethanes, one part moisture curing polyurethanes and UV/EB curable acrylates),
high solids solvent based (e.g., silicone), and
waterborne adhesives (e.g., acrylic emulsions).
A significant advantage of reactive 100% solids adhesive in addition to the reduction in possible VOCs is the possible elimination of drying ovens and resulting energy cost.
Heavy duty C.I. Cast iron & Heavy fabricated structure
Gravure type coating system
Liner type impression pressure assembly actuated with pneumatic piston for rubber roll Doctor blade and Nip Roller
Fully insulated imported special glass wool sheet fitted in the panel (Top side & Bottom) For controlling heat loss
One & One Slit type counter air flow arrangement, Divided equally are placed against roller for proper web support
Exhaust are distributed through-out the length of drying chamber & individual exhaust duct for each zone
Digital temperature controller with indicator & PT 100 sensor for each Zone
Inside heating for Nip Steel roller
Heavy duty Shaft types fix Rewinder with motor
A. C. synchronize Drive with Load cell
Center winding system / Surface
HOT AIR GENERATOR:
Diesel / Fired Air Heater
Thermic fluid Heater with Blower
Independent A.C. Drive
Pre Heating / Exhaust
Tension control Brake Unit with load cell feedback (Pneumatic/Motorized)
Moveable unwind with web guide