Bag making is the last process of plastic flexible packaging production and processing. If the quality of the bag is unqualified or the consumption is too high, the lighter means that the previous steps are abandoned, and the heavy claim is from the customer's claim, which has a significant impact on the company's production and operation. .
1. What should I do if the contents of the bag-making machine are not completely sealed due to heat sealing?
Reason: Poor anti-pollution heat-sealability of the film, mainly because the resin used in the inner seal layer is not suitable.
Countermeasure: Use anti-pollution heat-sealable film. Generally speaking, LDPE has moderate anti-pollution heat-sealability, EVA has good anti-pollution heat-sealability when the VA content is large, LDPE also has good anti-pollution heat-sealability, and ionic resins and metallocene polymers Has excellent anti-pollution heat seal.
2. What should I do if the sealing of the bag-making machine is brittle and brittle?
Reasons: (1) The heat sealing temperature is too high; (2) The pressure is too high; (3) The heat sealing time is too long; (4) The edge of the upper sealer is too sharp or the coated PTFE is damaged; (5 ) The silicone rubber at the bottom seal is too hard; (6) During the compounding and curing process, part of the adhesive penetrates into the film. The base material is affected by the penetration of the adhesive, the toughness (impact resistance) has decreased, and the brittleness has increased; (7) After the plastic composite packaging bag is cooled and placed, the heat sealing strength has increased, and it also has a tendency to become brittle .
Countermeasures: (1) According to the heat sealing characteristics of the material of the inner sealing layer, select the appropriate processing temperature, pressure and heat sealing time; (2) Improve the surface state of the upper heat sealing knife to make the surface of the sealer flat; (3) To gather The Teflon cloth is well covered; (4) Choose a silicone rubber pad of appropriate hardness.
3. What should I do if the bag is warped after heat sealing?
Reasons: (1) The thickness of the composite film is inconsistent; (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) The cooling is not Sufficient; (5) Insufficient curing time; (6) Poor heat resistance of the surface substrate film; (7) Improper tension control of the composite substrate during compounding, resulting in residual stress after curing and shaping, especially Such a failure is more likely to occur when the thickness of the composite film is thin.
Countermeasures: (1) Adjust the tension of the floating roller; (2) Select the inner sealing base material with low temperature heat sealability; (3) Adjust the heat seal temperature to an appropriate temperature; (4) Fully cool; (5) Fully ripen ; (6) Re-select the surface substrate film ;. (7) Adjust the tension of each part of the compound processing equipment, and try to make the retraction rate of the two substrates compounded as equal.
4. What should I do if the outer contour of the heat sealing surface is unclear? (Unclear knife lines)
Reasons: (1) Short cooling time; (2) Poor cooling plate contact; (3) The edge part is melted due to the heating of the silicone pad; (4) The longitudinal heat sealing force is uneven; (5) The edge of the heat sealing knife is not Neat and dull.
Countermeasures: (1) adjust the cooling time; (2) adjust the cooling plate; (3) replace or adjust the heat sealing knife; (4) prevent the edge of the silicone mat from overheating due to melting.
5. What should I do if the heat seal strength is poor?
Reasons: (1) The adhesive in the composite film has not been fully hardened; (2) The heat sealing conditions are not appropriate; (3) The distance between the heat sealing knife and the cooling knife is too long; (4) There is a problem with the inner sealing film ; (5) The heat resistance of the ink is poor, resulting in a decrease in the composite strength of the film at the heat seal portion; (6) Dust, POWDER spraying and other substances adhere to the hot cover; (7) The composite strength is low or the composite strength of the heat seal is reduced excessive.
Countermeasure:
(1) Promote the hardening of adhesive (aging and curing) through thermal insulation aging, and improve the composite strength and heat resistance of the composite film.
(2) Choose the best heat sealing conditions (temperature, time and pressure) according to the structure of the composite film, heat sealing state, etc., or improve the heat sealing method, and cool immediately after heat sealing.
(3) Check the storage period and storage conditions of the heat seal layer film. If the heat seal layer uses the film of the old batch number and the film subjected to heat seal treatment, special attention should be paid.
(4) Increase the thickness of the heat seal layer film.
(5) Change the type and grade of the heat seal layer film, and use the inner seal layer film with anti-pollution heat seal property.
(6) Check whether the grade of the adhesive meets the requirements (the exudation of low molecular substances in the resin may sometimes affect the composition of the adhesive).
(7) Improve the heat sealing performance of the heat seal layer (base material), control the content of the slip agent, and use mLLDPE film.
(8) Control the monomer content of MDI in the compound adhesive.
(9) Check the processing level of the hot cover.
(10) Replace the ink (preferably two-liquid type ink).
(11) Change the printing pattern of the packaging bag so that the part printed with ink avoids the heat-sealing part, or change the heat-sealing method. (Special attention should not be printed on the seal at the metal seal).
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