Case analysis of the most popular composite packag

2022-10-16
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Case study on the problem of weak composite packaging

problem of weak composite:

case 1 composite method: OPP and PE composite, with black, yellow, white and five color transparent patterns

phenomenon: the initial adhesion of the composite is good. After curing, except for the part where the white ink can tear the tape, the composite tension in other places is less than 1n, especially the transparent part has no adhesion

cause analysis: adopt the problem by problem elimination method

1. Membrane problems: the electric activation treatment of the membrane was measured, and the simulation method was used to test. It was found that OPP and PE membranes were qualified

2. Glue problem: ① check whether the glue amount meets the requirements: using the weighing method, the analysis result shows that the glue amount is more than 2.02g/㎡. ② The quality problem of the glue itself: according to the inspection records, the compound strength of the same batch of glue in other varieties is qualified. It shows that the possibility of glue quality problems is small

3. Ink problem: observe the printing film and find that the black ink is abnormal and shiny. After replacing the black ink, the fastness problem is solved

conclusion: ink problem

example 2 composite method: OPP, pet aluminized film composite. The patterns are green, blue, colorless and colorless, accounting for the main part

phenomenon: the initial adhesion of the composite is very good. The strip of the aluminized layer can be torn. After aging, except for the ink part, the colorless part of the aluminized layer can be transferred

cause analysis: adopt the problem by problem elimination method

1. Membrane problem: preliminary analysis by self-adhesive tape test method: the membrane should be preliminarily estimated to be qualified

2. Glue problem: carefully observe the composite film, and it is found that the soft and hard of the composite film is appropriate. It is estimated that the hardness of the glue is too high. During the aging process, the internal shrinkage affects the aluminized film, resulting in the transfer of the aluminized layer. The hardness of the film is too high, which may be caused by excessive curing agent or too hard structure of the adhesive itself. During the search, no shortage of curing agent was found. The film was made according to the glue ratio provided by the manufacturer, and it was found that the film was hard

conclusion: this adhesive should not be used as aluminum coating composite (or reduce the use of curing agent)

example 3 compounding method: OPP, pet, pet aluminized film compounding side by side. The pattern is mixed color plus silver on the front (aluminized reflection), and five colors transparent on the back

phenomenon: the front side (pattern side) is firmly bonded, and there is no bonding force on the back side

cause analysis:

1. Glue analysis: because the bonding of the front aluminized film is qualified, the possibility of glue problem is small

2. Film analysis: pet and OPP are compounded separately, which shows that the bonding is also "1035" Sinopec cast 200. After tensile test, the tensile strength and plastic characteristics of the material can be measured. The problem of film should be eliminated. Because the five color transparent part on the back is the composite of pet and OPP, it is likely that there is little glue or no pressure. Measure the thickness of the front and back sides of the package, and it is found that the thickness is inconsistent, and the back side is a little thinner

conclusion: the above phenomenon is caused by too little glue or no compaction

example 4 compounding method: OPP compounding with wood grain paper. The pattern is dark wood grain

phenomenon: the bonding is good, and there are many spots before and after aging

cause analysis: adopt the problem by problem elimination method

1. Glue analysis: Generally speaking, there is a high possibility that the glue amount is not enough, 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. Observe the spots carefully. It is found that the spots can be eliminated after compaction with nails, which indicates that there is a problem with the press roll. Check the press roll and find that the press roll is too hard (processed) and cannot be compacted between the two rollers. After replacing with a new rubber roll, the spots at the initial adhesion are greatly improved, but after curing, the spots still appear

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 of the old glue was moved into the paper hole before the glue was cured, which showed that the amount of glue was insufficient. After replacing the glue with a slightly faster curing glue, the problem was solved

case 5 compound mode: OPP and PE compound. The pattern is variegated, with more white ink and thicker ink layer

phenomenon: there are many small white spots

cause analysis:

1. Gluing amount: more than 3g/㎡

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 from left to right fade from brightness and finally disappear. It is suspected that it may be caused by equipment problems and uneven gluing. Stop the machine and measure the gluing gap with a micrometer. It is found that the gap is consistent. After careful observation of the gluing device, it is found that there is a problem with the gluing method. The glue always flows from left to right. Because of the hot weather, the ethyl ester volatilizes quickly, and the glue in the left glue tank of the structure is thin, and the glue in the right glue tank is thick. It seems that the inconsistent amount of glue causes small spots. Changing the way of glue application solves the problem

example 6: composite method: OPP and aluminum foil composite. The pattern is mottled

phenomenon: after compounding, the left side of each roll of inner core is about 20-25cm wrinkled. After changing various brands of glue, it still can't solve the problem

cause analysis: Generally speaking, the wrinkling phenomenon is caused by too little initial adhesion or too much tension (OPP). Because the use of glue is the best glue of various manufacturers, the output piston drives the load vibration to work and the solid content is 50%, it is reasonable that they have expressed their views, opinions and suggestions on the solution to the problem, and the possibility of insufficient initial adhesion of glue should be small. Adopt the elimination method one by one:

1. Reduce the tension (OPP), reduce the temperature of the drying channel (reduce the range of thermal expansion), and increase the pressure of the pressing roller. It is found that the wrinkling of the inner core has not been improved, and the wrinkling phenomenon caused by too much tension should be eliminated

2. Greatly improve the initial adhesion: Methods: ① improve the glue formula to produce glue with high initial adhesion; ② Increase the amount of curing agent; ③ Raise the temperature of drying channel; ④ Glue is prepared two hours in advance. Due to the use of all methods to improve the initial adhesion, the initial adhesion reached 5n/cm2

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

reprinted from: Chinese ink technology

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