The film quality is affected by many factors. in addition to objective factors, such as paper, ink, film, adhesives and so on, but also affected by subjective factors, such as temperature, pressure speed, glue and so on. These factors are not dealed with very well, it will lead to a variety of film quality problems.
1．Snow point on the products
The reasons to cause such problems are as follow:
(1) excessive powder on printed products: If the powder on printed products is too much and can not be completely dissolved by adhesives, It will be a large area snow points on the laminated products. In such cases, it should
appropriately increased the amount of glue, or sweep of powder on the printed products before lamination.
(2) too small glue: If the glue is too small, it will appear snow on the entire surface of the printed products. The solution method is to increase the amount of glue properly.
(3) improper pressure of the pressure roller: If the pressure of the pressure roller is too strong, the adhesives on the edge of the printed products will be extruded which will lead to the snow point on the edge of the printed products. And it will also happen the snow point under the smaller pressure. The solution method is to put the right pressure of the pressure roller.
(4) dry rubber on the glue roller: If it has dry rubber on the glue roller, then the glue will be small here, where will appear the snow points. The solution method is to clean the glue roller.
(5) Apron on pressure roll: If the adhesives, extruded from the edge of the printed products or the hole in the film, stick on the pressure roller. It will form dry aprons after a long time. Then when the latter printed products laminate the film, it will appears the tiny snow points. The solution method is to wipe the pressure roller on time.
(6) impurity in adhesives: If there are too much dust in the surrounding environment or dry rubber and the film fragment in the adhesive, the laminated products will appear snow points.. So we should pay special attention to the environment sanitation and if the adhesives can not be used out, we should pour them back to the barrel and sealed well or filtrated them before use.
2. Products bubble
(1) Printing ink is not dry: hot press firstly then glue or delay the lamination time till the ink completely dry.
(2) Printing ink is too thick: increasing the adhesive accordingly, increasing the pressure and composite temperature.
(3) The surface temperature of the composite roller is too high: use the cooling measure to reduce the composite roll temperature as soon as possible, such as air-cooled, close the electric wire and so on
(4) Dry temperature for lamination is too high: Dry temperature is too high, which caused the surface of adhesive crust and the products will bubble, In such case, the dry temperature should be appropriately reduced.
(5) Film reasons: If the bubble is caused by wrinkles or relaxation or uneven film or curling, then it can be solved through the adjustion of tension size or replace of the qualified film.
(6) the reasons of the concentration for adhesives: one another reason for bubble is adhesives at high concentrations, viscosity, or uneven coating as well as too less. Then you can use the thinner to reduce the concentration of adhesives or increase the appropriate quantity and eveness of coating .
(7) Pressure on pressure roller is too small: If bubbles are all over the printing surface, It’s because the pressure on pressure roller is too small. Then you can , increase the pressure on the pressure roller appropriately.
(8) against paper: There are bubbles in the joint between two pieces of paper because the two pieces of paper hold out against with each other before lamination. This phenomenon mainly happens in the lamination of thick paper. If the edge of the printing products is big, you can adjust the continuously variable transmission handwheel counter-clockwise to make two pieces of paper have a certain amount of overlap; If the edge of printing products is small, you can make the appropriate distance between the two pieces of paper, but pls note that the distance should not be very large. Otherwise. lamination products will appear film ends after cutting.
(9) lotus leaf edge of the printed products : Generally speaking, thousands and thousands printed products are stored together, which leads to the uneven moisture in the entire area and the edge will be wetter. Then it will cause lotus leaf edge. The printed products with lotus leaf edge will become flat under the lamination pressure but it will leave return to the origin state after leave from the pressure roller. Then it will cause bubbles. The solution is to wet or dry the printed products with lotus leaf edge.
3．Coated products appear wrinkled
The main reasons to cause the wrinkle of the coated products are uneven film transfer roller, the elastic inconsistency or wavy edge at both ends of film, too thick glue or uneven ends, inconsistent pressure and unequal line speed between electric roller and rubber roller. Then you can take measures accordingly by adjusting the transfer roller to the balance, changing the film, adjusting the volume and improving the drying channel temperature, adjusting the electrict roller and rubber roller position and process parameters and so on.
4．The bad bonding at the edges
This phenomenon mainly occurred in the thick paper lamination. Thick paper has some curl deformation in the collection. The diameter is smaller, it will be more obvious. The wet lamination products just left from the pressure roller are often pushed up by the curl paper at the edges, which will lead to bad boning there. Therefore, in order to improve the lamination products yield, you should minimize the width side at the edges to lest to ensure that the width with bad bonding will be in the range of model cutting.
5．Lamination products turn up
The main reasons for such problem are as follow:
(1) printing products is too thin: try your best to avoid the processing to the thin paper.
(2) tension imbalance: adjust to the film tension, so as to achieve the balance
(3) composite pressure is too large: to reduce the composite pressure appropriately.
(4) the temperature is too high: to reduce the composite temperature.
(5) tension of film is too large: If the tension of film is too large, it will make films elongated and deformed. And the finished products will be curled to one side after external force is removed and the films return to its original state. The solution is to adjust the screw depth of the screw to film swelling and reduce the braking force.
(6) winding tension is too large: If the winding tension is too large, both of film and printed products will also be deformed, but at the different deformation. Then the product will be curled to one side of paper after external force is removed, expecially the tissue paper. Solution is to reduce the friction of winding powered wheels.
(7) Environment humidity: Lamination products with high moisture content will distort after sufficiently dry and lead to the finished products curl to one side of the paper. Solution is to control the humidity in the workshop.
(8) drying time is too short: short drying time lead to not fully dry lamination products,then it will curl. Solution is to extend the drying time.
6．Products with bad bonding
The main reasons are as follow:
(1) improper selection of adhesives, improper coating volume, the wrong ratio of the measurement: to re-elect the adhesives and coating volume and exact matching.
(2) poor conditions on the surface of printed products, such as dusting, too thick ink, wet ink etc. causes bad bonding. Then it should gently wipe the dusting with a dry cloth or increase coating volume, increase the pressure or use the light to hot press then coating or use the adhesives with high solids or increase the coating thickness or increase the drying temperature to solve the problem.
(3) adhesive is absorbed by ink and paper and cause insufficient coating: it can consider to re-set formula and coating volume.
(4) too little glue: the glue is less, the solid content will be less, then bonding is certainly not enough. The solution method is to increase glue.
(5)large printed area on printed products: bad bonding due to the smooth surface of printing ink which cause the adhesives difficult to wet, proliferation and Infiltration. The solution is to increase the solid content of adhesives and the thickness of glue and to Improve the ambient temperature of lamination.
(6), deterioration of glue: check out the date of manufacture and shelf life before use..
(7) durability of film become invalid.
7．Uneven coating
The situation, such as Uneven thickness of plastic film, small composite pressure, film relaxation, swelling or deformation of roller caused by some curring adhesives in plastic tank, will cause uneven coating. So if it happen such problem, it should check out the reasons and take the corresponding measure and confirm whether it should adjust to the traction, increase composite pressure or the replacement of film rolls, glue and adhesives.
8．Products become into black
This mainly occurrs in the large area of bronze printing and gold stamping products. This is because the elements with high active characteristics in the adhesives and gold powder have chemical reaction. The solution method is to use of special gold ink or special adhesive or stamp after lamination.
