< p> < / p> < p> composite bag heat sealing quality has always been a packaging manufacturer to control the quality of the products is one of the most important project.
The following of several factors affecting heat sealing process, hope to help you!
< / p> < p> < / p> < p> packing bags of food packaging
composite heat sealing quality has always been a packaging manufacturer to control the quality of the products is one of the most important project.
Here are the influence factors of heat sealing process: < / p> < p> < / p> < p> 1, the heat sealing layer of material type, thickness and quality has a decisive effect on the intensity of heat sealing.
General composite food packaging common heat sealing material with CPE, CPP, EVA hot melt adhesive resin and other ionic co-extrusion or blending modified membrane.
The thickness of the heat sealing material in 20 ~ 80 & mu;
M between, special circumstances also have up to 100 ~ 200 & mu;
The same kind of heat sealing material, the heat sealing strength increases with the increase of the thickness of the heat sealing.
Retort pouch heat sealing strength of the general requirements of 40 ~ 50 Newton, as a result, the heat sealing material thickness shall be in 60 ~ 80 & mu;
< / p> < p> < / p> < p> 2, heat sealing temperature on the influence of heat sealing strength most directly.
Melting temperature of various materials, directly determine the minimum heat sealing temperature compound bag.
The production process, due to the heat sealing pressure, bag making speed and the thickness of the composite substrate aspects of influence, actual use of heat sealing temperature tend to be higher than the melting temperature of the heat sealing materials.
The smaller the heat sealing pressure, require heat sealing temperature is higher;
Machine speed faster, the surface of composite membrane material is thicker, the requirements of the heat sealing temperature is higher.
If the heat sealing temperature is lower than the heat sealing material softening point, no matter how to increase the pressure or extend the time of heat sealing, heat sealing layer are not real sealing.
But jorge sealing temperature is too high, and easy to damage welding edge heat sealing material melt extrusion, the produced root cutting phenomenon, greatly reduce the sealing heat sealing strength and impact resistance performance of the bag.
< / p> < p> < / p> < p> 3, to achieve the ideal heat sealing strength, a certain amount of pressure is essential.
For thin bags, heat sealing pressure to at least 2 kg/cm22, and as composite film thickness increases with the increase of the total.
Jorge sealing pressure is not enough, difficult to achieve truly fusion between two layers of thin films, and local heat sealing is not good, or difficult to catch all sandwiched between weld bubbles, the virtual welding;
Heat sealing pressure is not, of course, the bigger the better, should not to damage it is advisable to weld edge, because the high heat sealing temperature, welding and heat sealing materials are already in a molten state, too much pressure to squeeze out some hot sealing material, the weld edge forming half cut off state, weld crisp, heat sealing strength reduced.
< / p> < p> < / p> < p> 4, heat sealing time is mainly determined by the speed of bag making machine.
Heat sealing time is of the look of the welding seam sealing strength and a key factor.
The same heat sealing temperature and pressure, heat sealing time is long, the heat sealing layer fusion more fully, combined with the stronger, but the heat sealing time is too long, easy to cause weld wrinkling, affect the appearance.
< / p> < p> < / p> < p> 5, if the weld cooling after heat sealing is not good, not only affect the appearance of weld seam smoothness, and has a certain strength of heat sealing.
Through the under certain pressure, the cooling process with low temperature on just after melting heat sealing weld shapes, eliminate stress concentration process.
So the pressure is insufficient, cooling water circulation, circulation quantity is not enough, the water temperature is too high, or not timely will cause poor cooling, cooling heat sealing edge case become warped, heat sealing strength is reduced.
< / p> < p> < / p> < p> 6, heat sealing, the more the higher the heat sealing strength.
Longitudinal heat sealing number depends on the effective longitudinal welding rod length and the ratio of the bag length;
Lateral heat sealing number by the lateral heat sealing device on the number of group decision.
Good heat sealing for heat sealing number at least more than two times.
General hot knife of bag making machine has two groups, and hot knife position overlap degree is higher, the better heat sealing effect.
< / p> < p> < / p> < p> 7, the same structure and thickness of the composite film, the higher the peel strength between composite layer, the greater the heat sealing strength also.
For low peel strength of composite products, weld damage is often a seam of composite membrane interlayer strip first, caused by the inside heat sealing layer independent damage under tension, and the surface material loss of reinforcing effect, heat sealing strength of weld greatly reduced.
If composite peel strength is larger, the welding between the upper layer stripping does not occur, measured by the actual heat sealing strength is much larger.
< / p> < p> < / p> < p> by understanding, we believe that the high rate of compound food bag broken bag is the cause of the second group of heat sealing hot knife parts not overlap, virtual welding near the heat sealing side, the CPP film thinning, part of the structure is damaged, in cooking in thin layer of CPP can't afford to pressure and broken bag.
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