Printing problems and solutions of the hottest mil

2022-08-23
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Printing problems and solutions of milk packaging film

various problems often occur in the printing and production of milk packaging film. The following is a summary of the solutions to these problems, hoping to be helpful to you

problem 1: the reason for the poor adhesion fastness of the ink

(1) the surface tension of the film material is low, and the wettability to the ink is poor

(2) during the blowing process of the film, excessive smoothing agent is added to reduce its surface tension

(3) additives (plasticizers, smoothing agents, etc.) in the film migrate and precipitate to the surface, forming a weak interface layer

(4) the film surface is not clean, and foreign matters such as grease and dust are adhered

(5) the ink itself has poor quality, poor affinity for plastic film, or the ink has deteriorated

(6) the ink is not dry well and there are many residual solvents

solution:

(1) update the plastic film and corona the film

(2) replace the plastic film to ensure that the amount of lubricant is properly controlled during the film blowing process

(3) clean the surface of the plastic film and remove the oil and dust on the film surface

(4) change the ink

(5) reduce the printing speed appropriately, increase the drying temperature, and ensure that the ink is fully dry

problem 2: cause of printing film adhesion problem

(1) the content of lubricant in film material is low, and it is sticky itself

(2) the ink is sticky and the softening point of the binder resin is too low

(3) the ink is not completely dried, part of the solvent is not volatilized, and the residual solvent continues to penetrate after the printing film is placed for a period of time

(4) the printed film is rolled directly without sufficient cooling

(5) excessive winding tension

(6) the temperature and relative humidity in the workshop or warehouse are too high

solution:

(1) replace the film substrate material

(2) change the ink

(3) reduce the printing speed appropriately, increase the temperature of the drying oven, and increase the air volume, so that the ink can be completely dried

(4) the printed film must be fully cooled by the cooling roller before winding

(5) on the premise of ensuring orderly winding, the winding tension should be minimized, and the winding diameter should not be too large

(6) pay attention to controlling the temperature and relative humidity in the workshop

problem 3: the printing film has peculiar smell. Reasons

(1) add some odorous additives in the film production process

(2) the printing speed is too fast, the drying system is not strong enough, the ink is not fully dried, and more solvents remain in the film

(3) during the printing process of plastic film, a large number of solvents with high boiling point and odor were added to the ink, which were not completely dried, and there were still many solvents left in the film

solution:

(1) replace the plastic film

(2) reduce the printing speed and fully ventilate to ensure that the ink is fully dry

(3) do not use or use less smelly high boiling point solvents

problem 4: the printing film frosts. The reason for the problem

(1) the film is stored for too long or the content of smoothing agent in the film is high

(2) the temperature in the warehouse or printing workshop is too high, and the migration of smoothing agent is aggravated

solution:

(1) replace the film material

(2) control the temperature and humidity of the warehouse and printing workshop to ensure good ventilation

problem 5: reasons for inaccurate overprinting

(1) the thickness of plastic film is uneven, with ruffles, thickness, etc

(2) the drying temperature of the printer is too high or the strength of the hot air drying system is too high

(3) the tension of each part of the printing machine is set improperly

solution:

(1) replace the polyethylene film with small expansion rate

(2) replace polyethylene plastic film with uniform thickness

(3) appropriately increase the printing speed, reduce the temperature of the drying oven, and try to reduce unnecessary hot air drying

(4) adjust the tension setting of the printer

problem 6: cause of biting problem

(1) the drying speed of the first color ink is too slow

(2) the second color printing pressure is too high

(3) printing speed is too fast

solution:

(1) speed up the dry solvent in the first color ink, and increase the air volume and oven temperature of the first color ink

(2) appropriately reduce the printing pressure of the second color

(3) operate properly and flexibly to reduce the printing speed

problem 7: the heat sealing performance of milk film is poor. The reason for the problem

(1) when blowing polyethylene film, recycled raw material is mixed into 2.1 proprietary and unique computer control system

(2) during film blowing, the expansion ratio and traction ratio are too large, resulting in poor film heat sealing performance

(3) the dew point line is too low, which makes the molecules stretch laterally

(4) the extrusion temperature is too high during film blowing, resulting in the decline of the heat sealing performance of the film

(5) the content of smoothing agent in the film is too high, which affects the heat sealing fastness of the film

solution:

(1) re blow the film with new material

(2) the inflation ratio and traction ratio should be appropriately smaller, generally controlled between 1.5 ~ 2

(3 experimental machine is no exception) the dew point line should be controlled higher, so that the inflation and traction can be carried out under the melting point of polyethylene resin as far as possible

(4) appropriately reduce the extrusion temperature, which is generally controlled between 1600c and 1800C

(5) properly reduce the amount of lubricant during film blowing

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