Material preparation for operation (priming) is very important. Before the bonding process is necessary to determine the surface tension (surface energy) of each material with ink test.

Surface energy is one of the key criteria for adhesion to a variety of adhesive material, plastic and metal surfaces. This energy is measured in mN/m (modern units) or dyn/cm (old unit having the same numerical value). Apart from some exceptions, the higher the surface energy of the material, the better the adhesion of the adhesive substances to the surface. Low surface energy may be in the specificity of the materials, the surface of which needs to be chemically or physically treated surface contamination. If the surface energy is below 38 mN/m, adhesion would be bad. The same parameter is a starting in tests.

Surface energy check using the ink test applying the ink strip onto the surface of the material. If the ink strip on the surface of the material retains its shape without separating into droplets, at least 2 seconds, the surface energy of the material is the same or higher than the surface energy of the ink. In this case it is necessary to repeat the test with ink to the surface of the high level of energy. This rule works in the opposite direction. If the surface energy of PVC films below 38 mN/m, it cannot be used. It is necessary to make a special treatment of the film surface on a special device.

For PVC sheet requires additional chemical priming despite adequate ink test to remove contaminants in the form of dust, chalk precipitates paraffin residues and internal lubricants used during extrusion. Installation for laminating and laminating sheets KAM FL, equipped priming station, allowing in online, clean sheet of all kinds of mechanical impurities and to achieve the necessary degree of energy surface bonded sheets.

Our PVC/HPL flat lamination line is equipped with a special automatic chemical priming station. Materials must be clean, dry, acclimatized to the temperature of the working room. Often, many manufacturers are working in the winter at low temperatures in areas where the lamination machines placed. We had the experience of our lines start at the +4oC, so the temperature of the film and sheet was +4oC too, which fact is unacceptable, because melted glue getting with cold sheet, instantly cools, losing the adhesion ability. Our equipment (lamination lines) are designed to meet the reality of manufacturing and equipped with a powerful drying tunnel, that is located after the priming station, which is draining the primer off and heating the PVC and HPL to the operation temperature of 40-50oC.

Configuration of lamination lines for HPL PVC sheets. 

The feeding table is formed as a driving roller conveyor or as a stationary section with rubberized drive shafts that are synchronized with the movement across the line of shafts. 

Primer station is made of materials resistant to methylene chloride (dichloromethane), which is the main component of the primer. Application of primer is carried out across the width of the sheet for the uniform distribution is used Electro technical felt a thickness of 4-6mm. The primer can be made by or to use an existing product. Ask us how to prepare a primer. The market is well established primer KLEIBERIT 831.0, produced by German company KLEBCHEMIE MG Becker GmbH. 

The drying tunnel of lamination line must provide complete evaporation of methylene chloride from the surface of the sheet; for this the temperature should be within the tunnel above the boiling point of methylene chloride of 40 °C, but not above the melting temperature of PVC sheet. Depending on the speed of movement of the material, ambient temperature, quantity of the material being bonded and a primer applied onto the surface of the material, the operator exposes the necessary number of heating zones. The temperature of PVC (HPL) sheet entering the glue spreading unit must be at least 40-45 °C.

Glue applicator, designed for the application of polyurethane reactive melt adhesive (PUR HOT MELT), consists of metering and applicator shaft coated with a heat-resistant silicone to withstand temperatures above 250 ° C. Dosage of glue occurs by changing the distance between the shafts. Both shafts have their own heating system and temperature control, allowing you to maintain the proper operating temperature. Shaft’s operating temperature is depending on the adhesive material and it is between 110 °С and 150 °С. Melted polyurethane adhesive (PUR Hot Melt) uniformly applied to the surface of PVC sheet.

In laminating line KAM Flatlam is provided with an application unit for decorative PVC film coating and protective PE film on the list, which consists of two unwinder pairs of rollers and two pressing rollers. Important! To prevent thermal shock and premature film formation in adhesive fugue it is necessary to provide the heating of the decorative film to the temperature of 40-50 °С in the place of the compound of film and PVC. Polyethylene protective film does not require additional heating, but must be acclimatized to the room temperature.

The output roller can be driven as well as static.

 Laminating process (lamination) is as follows:

Workers feed PVC (HPL) sheets on the feeding table one by one, than sheet enters the priming station in which the primer is applied onto the surface.

Thereafter, the sheet enters a drying tunnel where the evaporation of methylene chloride, and heating the sheet to a desired temperature. Heated sheet enters the adhesive rolls by which it is applied heated to the required temperature PUR (PUR) hot melt adhesive.

Glue melting is possible to perform directly on the shafts or using pre-melting station designed to work on polyurethane reactive hot melt adhesives. The main melting stations producers are Nordson EFD England and Robatech Switzerland.

Then the sheet with the adhesive gets into the decorative film application unit wherein the film is rolled with rubberized rollers, thereafter the protective film is been applied upon the decorative film. After that the worker cut the film at the end of the sheet and place the laminated material out of the working zone.

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