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Several common flexible packaging quality problems

1. Aluminized transferCommon aluminum plating has aluminum platingCPPand aluminizedPETaluminized transfer usually occurs in aluminizedPET, as it is often used in mid-layer composites. AluminizedPET, I understand that there are two types: one is the aluminum plated, and the other is the transferred aluminum. The effect and adhesion of the two types of aluminum plating are different. The plated ones are better, and many of the transferred products are badly bought by enterprisesPETAfter processing and transferring, the adhesion ability is poor. This is because the peel strength of the film itself is too low, and the bonding firmness between the aluminized layer and the base film is relatively poor.The normal aluminized film is to have a layer of primer on the vacuum aluminized surface of the substrate to improve the adhesion of the aluminum layer, then vacuum aluminum on the primer, and then coat the aluminum layer with a double-layer coating. Polyurethane glue is used as the top coating to protect the aluminized layer from falling off. The aluminized layer of this aluminized film has good firmness and is not easy to fall off. In order to save production costs, some aluminized film manufacturers do not use primers when producing aluminized films. The adhesion of aluminum plating is low and not strong, so it is easy to fall off. Therefore, plastic bag manufacturers should pay attention to the difference when purchasing materials.Another factor that may cause the transfer of aluminum plating is that after pulling it apart, it is found that there is aluminum on both sides of the aluminum plating and the substrate. Obviously, this shows that the film has undergone secondary aluminum plating, which is the material manufacturer for some reason. The film was aluminized twice, resulting in aluminization transfer.Another factor that triggers the transfer of aluminum plating is the cause of glue. Ordinary glue has a relatively small molecular weight and strong activity, which is easy to penetrate into the aluminum plating, affecting the adhesion of the aluminum plating, resulting in the transfer of the aluminum plating. At the same time, the current solvent volatilization and release ability is poor, and the glue can easily penetrate into the aluminized layer, destroying the aluminized layer. transfer.Now the solution of most manufacturers is to reduce the addition of curing agent. In this way, the effect of the transfer of aluminum plating has changed, but the symptoms are not cured. With the change of the weather and the change of the temperature and humidity of the workshop, it is difficult to control the amount of curing agent, which may cause the problem of batch production of defective products. Because most of the problems of compounding need to be cured before knowing how to deal with it, it is too late to find out after curing. So I don’t recommend using this program often.In terms of glue, I recommend choosing an adhesive with moderate molecular weight, relatively uniform molecular weight distribution, and low initial tack. The characteristics of water-based adhesives can meet the above requirements. The molecular weight of water-based adhesives is that of solvent-based adhesives10times, and the molecular weight distribution is relatively uniform, and there is no possibility that the aluminum plating layer will be damaged due to solvent penetration, so it will not affect the adhesion fastness of the aluminum layer, and it will not lead to the transfer of aluminum plating. Water-based adhesives are currently widely used in aluminized packaging, such as Shanghai Longhong’s two-component water-based adhesives.268, Rohm and Haas’s one-component water-based90DThere are unique advantages in this regard. Therefore, in solving the transfer problem of aluminized film, the choice of adhesive is very important.Another reason for the transfer of aluminum plating is improper operation by the technician. The inappropriate operation method is manifested in the following aspects: ·If the operating tension is too large, the aluminized film will be stretched, resulting in elastic changes and transfer; ·The amount of glue applied is too large, resulting in volatilization not drying, false drying, and solvent residue leading to transfer; ·Excessive residual solvent will destroy the aluminum plating. Because the aluminum plating layer of the aluminum plating film is relatively thin, it is inevitable that there will be some pinholes, so that the residual solvent will penetrate in, destroying the aluminum layer and causing the transfer of aluminum plating;The above is some analysis on the transfer of aluminum plating. I personally think that reducing the amount of curing agent is not advisable. Enterprises can choose enhanced aluminum plating or plated aluminum plating to solve this problem. Do not use transferred plating. Aluminum and secondary aluminized materials.2. Retort packaging bagsThere are many problems in cooking, the common ones are delamination, wrinkling, swelling, air leakage, odor and other problems. 1, delaminationDelamination is the process of packaging121The phenomenon of material delamination occurs after sterilization at ℃. Usually nylon reheatedCPP, The material and ink glue must be high temperature, and this problem can be solved by paying attention to the amount of glue in operation. 2, wrinkledMany companies find that the product is good out of the oven, but after the bag is made, they find that the bag sealing edge has wrinkled phenomenon, which is typically caused by insufficient curing time. After the bag is cooled, it will be found that the edge is wrinkled, and it should be immediately returned to the curing room for curing. 3,Inflated bag, air leakageWhen this happens, first identify where the problem is, and use the elimination method to find out the problem one by one. When the food is packaged and vacuumed and then cooked and sterilized, it is found that the bag is inflated and leaking. Then take the package and squeeze it in water to see where the air leaks. Usually, when most of the customers are packing food, the sealing is not strong due to the oil in the food. In addition, high temperature sterilization will cause the above-mentioned air leakage and swelling, which will cause peculiar smell after a long time.The above are common problems with two-layer cooking. Now let’s analyze the cooking problem of the next three layers of aluminum foil. Delamination is usually the delamination between the mask and the aluminum foil. In the analysis of this problem, I believe that you will not use the glue wrong. It should be cooking glue. You can change two glue tests. If this happens, it is not a glue problem. , the material should be considered: fabric and foil. Whether the surface of the aluminum foil has been cleaned, whether the fabric used can be high temperature, whether the dyne value has been reached, the problems need to be solved one by one. Its air leakage is the same concept as the air leakage of the two-layer structure. In the place where the sealing is not good, the air leakage of the inflation bag will occur. After a long time, it will emit peculiar smell. Because of the air leakage, some additives in the food and food Odors will occur as the bag oxidizes as it combines with oxygen. When odor occurs, pay attention to the selection of fabrics.PETAlthough both nylon and nylon can be used as fabrics, butPETIt is a polar material and absorbs oil. Here we can do a small experiment, usingPETre-aluminum foil re-high temperatureCPP, and nylon compound aluminum foil compound high temperatureCPP, put in the same food, vacuum sterilize and clean it, and put it there to dry, you will findPETIt feels sticky to the touch and nylon doesn’t, that’s the difference. becausePETabsorbs oil, so over time we will findPETA little odor, nylon will not have a odor.3. Aluminum foil breaksMany manufacturers who do high-temperature cooking of aluminum foil will find that the aluminum foil will break after vacuum sterilization, like cutting it with a knife. for example10The aluminum foil of the silk has the problem of breakage after vacuum cooking. If the breakage is relatively small, it is necessary to consider changing the material. Consider whether the material of the inner layer is soft or hard. If it breaks, you have to choose a softer material, or increase the thickness,1A wire would be better too. This is often the case with four-layer structures. The usual four-layer structure isPET/AL/PA/RCPP, we calculate the thickness12Silk, which also often breaks. Because half of the material of the four-layer structure is relatively hard with bone, after vacuuming, there will be fractures in the places with bone teeth and wrinkles. Although it is subtle, it will affect the product for a long time, so it is necessary to thicken the inner layer, or Choose a softer material for the inner layer.Fourth, the opening is not goodPoor opening means that after the bag is made, it is not easy to rub it at the opening of the bag, which will make it more troublesome for customers to load food. CPPIf the openness is not good, you must first tell the material manufacturer that the material with good openness is required, and pay attention to the operation when you produce it yourself: First,CPPThe unwinding tension, the first is the winding tension, and then the temperature of the curing and the cold knife of the bag making can be solved.PEThe mouth opening is similar to this,PEThe unwinding tension must not be large, why? Because the tension is too large, it will stretch it, the temperature of the hot roller should not be too high, the winding tension should not be too high, and the curing temperature should not be too high.5. Frequently Asked Questions about Summer CompoundingAnother thing to pay attention to in summer is glue. For example, employees have to mix glue frequently before leaving get off work, and a set is divided into four times, so that there will not be too much glue left after get off work, just add some solvent and put it in the refrigerator for storage, and add it slowly when using it the next morning. Go in, don’t mix it all at once. In summer, the glue has more bubbles in the plastic tray, and it is all white foam. This is because the volatilization is relatively fast, and the high-speed operation of the glue in the plastic tray causes the foam to turn white, so it is necessary to add solvent frequently, and use less and more glue. , also to avoid ghosting.In summer, the temperature is high, and it is necessary to control the performance of the material. Know how to control as the weather changes when compounding each material.Minimize mosquitoes, make a separate window screen, install mosquito-killing lamps and air shower doors, and spray mosquito-killing water after get off work every night. This is unavoidable and must be done.

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