The hottest inventory of bag making mistakes made

Check the bag making mistakes made by 90% of the flexible packaging factories

release date: Source: Internet editor: lychee browsing times: 885 copyright and disclaimer

core tip: bag making processing is the last process of plastic flexible packaging production and processing. If the bag making quality is unqualified or the consumption is too high, then the previous processes will be wasted, The most important thing is to claim for compensation from customers, which has a significant impact on the production and operation of the enterprise

[China Packaging News] bag making and processing is the last process of plastic flexible packaging production and processing. If the bag making quality is unqualified or the consumption is too high, then at least the previous processes will be wasted, and at most the claim from customers will have a significant impact on the production and operation of the enterprise

1. How can the incomplete heat sealing of bag making machine and the mold locking force of the press be 30 tons, resulting in the leakage of contents or the deterioration of relevant data? How is it bound to constitute a demonstration and driving effect

cause: the anti pollution heat sealing property of the film is poor, mainly because the resin used in the inner sealing layer is inappropriate

countermeasures: use films with good pollution resistance and heat sealing. Generally speaking, LDPE has medium anti pollution heat sealing property, EVA has good anti pollution heat sealing property when the VA content is large, LDPE also has good anti pollution heat sealing property, and ionic resin and metallocene polymer have excellent anti pollution heat sealing property

2. What about the brittle and broken sealing of the bag making machine

reasons: (1) the heat sealing temperature is too high; (2) Excessive pressure; (3) The heat sealing time is too long; (4) The edge of the upper sealer is too sharp or the PTFE covered is damaged; (5) The silicone rubber at the bottom seal is too hard; (6) In the process of compounding and curing, part of the adhesive penetrates into the film. Due to 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 plastic composite packaging bags has increased. There are factories in China for gold medical, and it also tends to become brittle

countermeasures: (1) select the appropriate processing temperature, pressure and heat sealing time according to the heat sealing characteristics of the inner seal material; (2) Improve the surface condition of the upper heat sealing knife to make the surface of the sealer smooth; (3) It is well covered with polytetrafluoroethylene cloth; (4) Choose silicone rubber pad with appropriate hardness

3. What about the warpage of the bag after heat sealing

reasons: (1) the thickness of 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) Insufficient cooling; (5) Insufficient ripening time; (6) The surface substrate film has poor heat resistance; (7) The tension matching control of the composite substrate in the composite process is improper, which leads to the residual stress after its curing and shaping, especially when the thickness of the composite film is thin

countermeasures: (1) adjust the tension of floating roll; (2) Select the inner sealing base material with low temperature heat sealing property; (3) Adjust the heat sealing temperature to the appropriate temperature; (4) Sufficient cooling; (5) Fully ripen; (6) Re select the surface substrate film;. (7) Adjust the tension of each part of the composite processing equipment, and try to make the retraction rate of the two composite substrates equal

4. What if the outer contour of the heat sealing surface is not clear? (the knife pattern is not clear)

reasons: (1) short cooling time; (2) Poor contact of cooling plate; (3) Because the silicone pad is heated, the edge part melts; (4) The longitudinal heat sealing force is uneven; (5) The edge of the 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 the edge melting caused by overheating of silicone pad

5. What about poor heat sealing strength

reasons: (1) the adhesive in the composite film has not been fully hardened; (2) Improper heat sealing conditions; (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 poor heat sealing property of the ink leads to the reduction of the composite strength of the film at the heat sealing position; (6) Dust, dusting and other substances are attached to the thermal cover; (7) The composite strength is low or the composite strength at the heat seal decreases too much

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(1) promote the hardening (curing and curing) of the adhesive through thermal aging, and improve the composite strength and heat resistance of the composite film

(2) select the best heat sealing conditions (temperature, time and pressure) according to the composition structure and heat sealing state of the composite film, or improve the heat sealing method, and immediately cool after heat sealing

(3) check the storage period and storage conditions of the heat sealing film. If the heat sealing layer uses the film of the old batch number and the film after heat sealing treatment, pay special attention

(4) increase the thickness of the heat seal film

(5) change the type and grade of heat sealing film, and use 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 sometimes affects the composition of the adhesive)

(7) improve the heat sealing performance of the heat sealing layer (substrate), control the content of the smoothing agent, and use mLLDPE film

(8) control the monomer content of MDI in the composite adhesive

(9) check the treatment degree of the heat cover

(10) change the ink (it is best to use two liquid 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. (pay special attention not to print metal ink on the seal)