Three of the thermal film’s laminating key technologies processes are laminating temperature, pressure and the speed of laminating.
(1). Laminating temperature
Temperature is the primary factor for laminating. According to practical experience, coating temperature should be controlled at between 95~130 Celsius degree.
(2). Laminating pressure
The paper surface is not smooth, and only under the appropriate pressure, molten state of hot melt adhesive will completely cover the printing surface. In actual production, adjust the pressure according to the different paper. For example, loose paper, the pressure should be stronger, instead of lighter for tight paper. According to experience, laminating pressure is generally set to appropriate 6 ~ 20MPa.
(3). Laminating speed
The speed of laminating determines the time of pre-coated adhesive on the heating roller and melting time on the film and paper contact time. Domestic facilities speeding rate is generally controlled between 15 ~ 80m/min.
(4). Special printing lamination controlling data
Special print refers to the large area printing, thick ink, deep color, large water content of paper, large size paper printing. To laminate on such printing sheet, the general laminating data is as follows for reference:
Lamination temperature: 95-115 degree Celsius
Lamination pressure: 16-25Mpa
Lamination speed: 5-10m/min
(5) Other factors which affect laminating quality
(1). Ink
It is better to use light quick-drying ink for printing on the product if it need to be laminated, but it is not good to put too much catalyst, otherwise the ink will crystallize on the surface. In addition, the ink viscosity, oil content etc. will affect laminating quality as well.
(2). The state of the Adhesive coating
BOPP film’s adhesive layer requires to be uniformity and thin, under the premise of the ensuring strong bond, should try to select the appropriate laminating thermal film with good adhesive; otherwise it will affect the quality after laminating.
Product has snow point
(1) Caused by: Rubber roll pressure is not enough; Solution: increase the pressure;
(2) Caused by: Adhesive on Laminating film is not completely melted; Solution:
Increasing the coating temperature
Increase the film and heating roller contact area, and the heat melt adhesive film will increase the degree
Reduce coating speed
(3) Caused by: Laminating film of the adhesive surface with dust; Solution: impurities, should be promptly removed.
Products with wrinkles
(1) Caused by: rubber roller too much pressure, resulting in membrane deformation; Solution: appropriately reduced pressure.
(2) Caused by: rubber roller surface damage, not smooth; Solution: replace the rubber roller
(3) Caused by: rubber roller and the pressure imbalance between the heating rollers; Solution: adjusted and have them balance
(4) Caused by: film inconsistent on both sides of the tension, or wavy edges; Solution: replace the thin films.
Defect after cutting curly products
(1) Caused by: film tension is too large, so that stretching deformation of membranes; Solution: membrane tension should be adjusted to the screw.
(2) Caused by: Winding tension, causing a deformation of film and paper at the same time; Solution: institutions should adjust winding tension.
(3) Caused by: Environmental humidity; Solution: humidity controlled workshop should be around 60%.
(4) Caused by: The drying time is short; Solution: To extend the drying time, to be coated products in the winding roller to dry completely cooled, then cut film down. speed, coating temperature increase.
Bond is not strong, film
(1) Caused by: Laminating film over shelf life; Solution: replacement of the laminating film.
(2) Caused by: printing ink containing an excessive amount of silicone oil, paraffin wax additive categories, metal ink, ink too thick, ink wasn’t dry. Solution: extend the print drying time, especially for special attention and when printed coated.
(3) Caused by: laminating pressure, high velocity, low temperature; Solution: increase coated pressure increase, lower coating speed, coating temperature increase.