1, aluminum foil bag color is not allowed

Reason: mainly the deviation of the diameter of the gravure cylinder; due to the incorrect plate loading, the deformation of the graphic; the spacing of the shaft teeth is uneven, the gap is too large or too small, or the top tooth phenomenon causes the overprinting is not accurate; The control is unbalanced or the thickness of the gravure film is uneven, the ruffle edge; the pressure between the plate cylinder and the platen roller is uneven or the pressure between the plates is inconsistent when the multi-color overprint is applied.

Gravure overprinting is not a major quality issue and is caused by many reasons. The practical experience is mainly due to the mechanical equipment. Because the mechanical equipment is not inspected and maintained during the long-term survival and operation, causing wear or obstacles of the mechanical structural parts, the overprinting will be inaccurate. This requires regular inspection and adjustment of each device; control of the plate making process to minimize plate errors; use of qualified film materials; and timely exclusion of misprints caused by other printing accidents.

2, aluminum foil bag heat seal strength difference

1) Effect of aluminum foil bag heat sealing material

Different types of heat sealing materials, different heat sealing strength, such as PP, PE / EVA heat sealing strength is inconsistent; the same film different polymerization methods of products, heat sealing strength is different; material thickness, uniformity, etc. will also affect the heat seal strength Different processing methods of the heat seal layer, such as blow molding, cast film, etc., all affect the heat seal strength. The storage time of the film is too long, the precipitates are increased, and the heat sealing strength is poor after corona treatment; the moisture absorbing material absorbs moisture, the thermal cover is delaminated, and the peel strength is decreased.

2) Influence of processing technology of aluminum foil bag composite film

The printing ink has poor temperature resistance or improper additives in the ink. At the high temperature of the bag, the printed layer is delaminated and the heat seal strength is lowered. Heat sealing should be designed to be as unpatterned as possible. The choice of binders in the composite process is also important. The compatibility of the binder ratio, viscosity and other parameters will affect the seal strength. In the extrusion compounding or coating process, the processing temperature is high, and the surface of the material is highly oxidized, which is disadvantageous for heat sealing.

3) The impact of the bag making process

The sealing of the seal after heat sealing is not enough, the shaping is insufficient, the internal stress cannot be eliminated, the strength and appearance are affected, and the cooling water circulation system should be inspected in time. The more heat seals, the higher the heat seal strength. The number of longitudinal heat seals depends on the ratio of the effective length of the longitudinal weld to the length of the bag; the number of transverse heat seals is determined by the number of combinations of the machine's transverse heat seals. Good heat sealing requires at least two heat seals.