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Skillfully solve the sealing problem of aluminum foil bag


click: time:2020-08-29 15:56:42 edit:Hua Di's editor

The sealing quality of aluminum foil bags has a direct impact on the whole packaging process, transportation and storage of the contents. What are the common sealing problems?

 

1. How to deal with leakage or deterioration of contents caused by incomplete heat sealing?

 

reason:

 

The anti pollution heat sealing performance of the composite membrane is poor, mainly due to the improper resin used in the inner seal layer.

 

Countermeasures:

 

The film with good anti pollution and heat sealing property is used. Generally speaking, LDPE has moderate anti pollution heat sealing property, EVA has good anti pollution heat sealing property when VA content is large, LDPE also has good anti pollution heat sealing property, ionic resin and metallocene polymer have excellent anti pollution heat sealing property.

 

2. How to seal brittle and brittle fracture?

 

reason:

 

(1) The heat sealing temperature is too high.

 

(2) Too much pressure.

 

(3) The heat sealing time is too long.

 

(4) The edge of the upper sealer is too sharp or the PTFE coated is damaged.

 

(5) The silicone rubber at the bottom seal is very hard.

 

(6) In the process of compounding and curing, a part of adhesive penetrates into the film. Because of the penetration of adhesive, the toughness (impact resistance) of the substrate decreases and the brittleness increases.

 

(7) After cooling and placing, the heat sealing strength of the plastic composite packaging bag increases, and at the same time, it tends to become brittle.

 

Countermeasures:

 

(1) According to the heat sealing characteristics of the inner seal material, the appropriate processing temperature, pressure and heat sealing time are selected.

 

(2) The surface state of the upper heat sealing knife is improved to make the surface of the sealer smooth.

 

(3) It is well covered with polytetrafluoroethylene cloth.

 

(4) Choose the appropriate hardness of silicone rubber pad.

 

3. How to do if the bag warps after heat sealing?

 

reason:

 

(1) The thickness of the composite film is not consistent.

 

(2) The heat sealing temperature is too high or the heat sealing time is too long.

 

(3) In the longitudinal heat sealing knife part, the running track of the composite film is not straight.

 

(4) Insufficient cooling.

 

(5) The ripening time is not enough.

 

(6) The heat resistance of the surface substrate film is poor.

 

(7) In the composite process, the tension matching control of composite substrate is improper, which leads to the residual stress after aging, especially when the thickness of composite film is thin.

 

Countermeasures:

 

(1) Adjust the tension of the floating roller.

 

(2) The inner sealing material has low temperature.

 

(3) Adjust the heat sealing temperature to the appropriate temperature.

 

(4) Cool well.

 

(5) Fully mature.

 

(6) Re select the surface substrate film.

 

(7) Adjust the tension of each part of the composite processing equipment to make the shrinkage ratio of the two composite substrates equal as much as possible.

 

4. What to do if the outline of heat sealing surface is not clear?

 

reason:

 

(1) The cooling time is short.

 

(2) Poor contact of cooling plate.

 

(3) As the silicone pad is heated, the edges are partially melted.

 

(4) The longitudinal heat sealing force is uneven.

 

(5) The edge of heat sealing knife is irregular and blunt.

 

Countermeasures:

 

(1) Adjust the cooling time.

 

(2) Adjust the cooling plate.

 

(3) Replace or adjust the heat sealing knife.

 

(4) Prevent edge melting caused by overheating of silicone pad.

 

5. How to deal with poor heat sealing strength

 

reason:

 

(1) The adhesive in the composite film has not hardened sufficiently.

 

(2) Improper heat sealing conditions.

 

(3) The distance between the heat sealing knife and the cooling knife is too long.

 

(4) There is something wrong with the inner seal film.

 

(5) The poor heat sealing performance of the ink leads to the decrease of the composite strength of the film at the heat sealing position.

 

(6) Dust, dusting and other substances adhere to the hot surface.

 

(7) The composite strength of the aluminum foil bag is low or the composite strength of the heat sealing part decreases too much.

 

Countermeasures:

 

(1) Through heat preservation and aging, the adhesive hardening (curing and curing) is promoted, and the composite strength and heat resistance of the composite film are improved.

 

(2) According to the composition structure and heat sealing state of the composite film, the best heat sealing conditions (temperature, time and pressure) should be selected, or the heat sealing method should be improved. The cooling should be carried out immediately after the heat sealing.

 

(3) Check the storage life and storage conditions of the heat seal film. Pay special attention to the film of old batch number and the film after heat sealing treatment.

 

(4) Increase the thickness of the heat seal film.

 

(5) Change the type and grade of heat seal film, and use the inner sealing film with anti pollution heat sealing property.

 

(6) Check whether the grade of the adhesive meets the requirements (the exudation of low molecular substances in the resin may affect the composition of the adhesive sometimes).

 

(7) LLDPE film was used to improve the heat sealing performance of the heat sealing layer (substrate) and control the content of the lubricant.

 

(8) Control the content of MDI monomer in the composite adhesive.

 

(9) Check the treatment degree of the heat cover.

 

(10) Change the ink (two liquid ink is preferred).

 

(11) Change the printing pattern of the aluminum foil bag to make the ink part avoid the heat sealing part, or change the heat sealing method. (pay special attention to the metal ink not to be printed on the seal).

 

See here, I believe you have a certain understanding of how to solve the problem of aluminum foil bag sealing. Of course, if you are looking for aluminum foil bag manufacturers, you may as well call us for advice. We are dedicated to serving you

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