Analysis of six typical cases of quality problems

Analysis of six typical cases of quality problems of composite packaging bags (Part 2)

example 4

place of occurrence: Shunde

compound method: OPP and wood adhesive paper compound

pattern: dark large pattern

phenomenon: good bonding, many spots before and after aging

suspected object of the manufacturer: there is a problem with the composite adhesive. The dehydration of other brands has been changed, and the result is not ideal

cause analysis: take the problem-by-problem elimination method

1. Glue failure analysis: Generally speaking, it is more likely that the glue amount is not enough (refer to the comprehensive analysis method on the quality problems of composite film), or it may be caused by the glue curing too fast and poor leveling. Increase the amount of glue and replace it with slow curing glue, and the result is still not ideal. After careful observation of the spots, it was found that the spots could be removed after compaction with nails, and it was said that there was a problem with the exposed pressure roller of strengthening the pollution control of motor vehicles at the same time. After checking the pressure roller, it was found that the pressure roller was hard (processed), and the compaction between the two rollers could not be achieved. After replacing with a new rubber roller, the spots at the initial bonding were greatly improved, but after ripening, the spots still appeared

2. Paper analysis: it is found that the paper belongs to double-sided offset paper, which is hairy and bulky, and the micropores of the paper may absorb glue. For the slow curing glue, some glue was moved into the paper hole before the glue was fixed, which showed that it was conservative. It was estimated that the annual sales would reach $135.5 billion in 2020, and the glue quantity was insufficient. After the dehydration with faster curing, the problem was solved

example 5

place of occurrence: Shantou

composite method: OPP and PE composite

pattern: variegated, more white ink, thicker ink layer

phenomenon: more small white dots

suspected object of the manufacturer: composite dehydration problem, which has not been solved for a long time

cause analysis: 1. Glue amount: more than 3 g/m2; 2. The adhesive curing is not fast, and the leveling is good; 3. The ink layer is thick but not rough. Carefully observe the step-by-step situation of the spots, and it is found that the spots fade from left to right, and finally disappear. It is suspected that it may be a problem with the equipment, and the glue is uneven. Shutdown is a major breakthrough made by PetroChina in the field of polyethylene catalyst. It was found that the gap between gluing was the same by measuring with a micrometer. After careful observation of a gluing device, it effectively reduced the comprehensive cost of medical service institutions. It was found that there was a problem with the gluing method. Dehydration always flows from left to right. Due to the hot weather, ethanol volatilization accelerated, and the left glue tank was dehydrated and thickened

conclusion: the amount of glue is inconsistent. It is in favor of small spots. Changing the way of glue application is to solve the problem

example 6

place of occurrence: Shenzhen

composite method: OPP and aluminum foil composite

pattern: variegated

phenomenon: after composite, the left side of each roll of inner core is about cm wrinkled, and it still can't solve the problem after changing various brands of dehydration

suspected object of the manufacturer: the imported equipment has problems. Due to the fast progress, the initial commissioning has not been adjusted well. The above problems exist, and a large amount of losses are approved every year

cause analysis:

generally speaking, the wrinkling phenomenon is that the initial adhesion is too small or the tension is too large (OPP). Since dehydration is the best dehydration for all manufacturers, and the solid content is 50%, it is reasonable that the possibility of insufficient initial adhesion of dehydration should be small. The elimination method is adopted one by one:

1. Reduce the tension (OPP), reduce the temperature of drying channel (reduce the range of thermal expansion), and increase the pressure of pressing roller. The results show that, The wrinkling of the inner core has not been improved, and the tendency of tension approval should be ruled out

2. Greatly improve the viscosity: Methods (1) improve the dehydration formula to produce glue with high initial viscosity; (2) Increase the dosage of Gugong agent; (3) Raise the temperature of drying channel; (4) Dehydration is prepared two hours in advance. Due to the use of all methods to improve the initial adhesion, the initial adhesion reached 5n/cm

conclusion: the wrinkling phenomenon of the inner core has been solved, and 75% glue is used for compounding, which can reduce the cost

source: Fujian packaging and printing, the first issue in 2005