Answers to the problem of soft plastic packaging
DATE：2019/5/6 9:16:07 / READ： / SOURCE：This station
Answers to the problem of soft plastic packaging
(1) When the 150g/m2 paper is extrusion coated, the temperature at 315 °C is still not strong enough to peel off. Why? How to deal with it? (Used LDPE particles, paper is white paper)
If it is ordinary paper, that is, paper which has not been treated with any polymer, it is applied by extrusion flow, and good adhesion is obtained without any primer or corona treatment. Since paper is a porous material, it is easy to bond with molten LDPE. On the contrary, if the paper has been pre-impregnated or pre-coated with a certain polymer, it should be corona treated, then coated with AC agent and Increase the LDPE temperature. Generally speaking, increasing the temperature of LDPE extrusion is advantageous for the fastness of extrusion coating. As long as it does not cause decomposition of LDPE, the decomposition temperature of LDPE is above 315 °C.
(2) The factory has two ternary co-extrusion compounding machines, which products can be developed and produced?
The co-extruded composite products that can be developed and produced are: the first can produce frozen food packaging film: PP/EVA/LDPE) Because PP has a good affinity with LDPE, it is not very good, so adding EVA is beneficial to PP and LDPE bonding. Increased fastness. The above structure can also be used for packaging of dry foods, such as biscuits, instant noodles, fried rice, etc., and the use of coextrusion compound is cheaper than the complex price, and is competitive. The second can produce milk packaging bags, LDPE is black, PP is white, this bag can be hot-filled at 80C, but it is a simple bag and can only be stored for about 3 days. Thirdly, it is possible to produce a wrap-around packaging film which is tacky on one side and not sticky on the other side.
(3) The current mustard bag packaging, widely used BOPP / reverse printing / DL / VMAICPP structure, this structure, often the reverse printing ink is glued together by PU adhesive, and peeled off BOPP, why?
The dry composite adhesive contains a large amount of ethyl acetate solvent, and ethyl acetate is an excellent solvent for the reverse printing ink binder. When the two-component polyurethane adhesive is coated on the reverse printing ink, the ethyl acetate in the rubber penetrates into the ink. In the middle, the ethyl acetate enters the printing surface of BOPP, causing loosening or even delamination of the bonded portion between the printing ink and the BOP, and the penetration of the ethyl acetate with the PU glue on the ink layer is improved. The bonding strength of the entire printing layer with the PU glue, the result is the original
The anti-printing ink with good adhesion is separated from the BOP film. The solution is to apply PU glue on the vacuum aluminum plated surface of VMAICP film, and after the drying process at 60-90 degrees Celsius, it is combined with the reverse printed NOPP film. Thus, when the reverse printing ink is in contact with the PU glue, the PU glue It has been dried by a drying tunnel, in which the ethyl acetate content has been largely volatilized, and no penetration of ethyl acetate into the reverse printing ink layer is caused, which affects the adhesion of the ink layer to BOPP. Simultaneously
Increasing the PU cement content (reducing the amount of ethyl acetate solvent), increasing the temperature of the drying tunnel, and increasing the time to stay in the drying tunnel (slowing the composite speed) can improve and prevent such delamination.
(4) When producing instant noodle cover materials, the paper is not easy to be composited with aluminum foil, and is also a PU two-component adhesive used. Why? The instant noodle cover material structure is PET/reverse printing/PU glue/paper/PU glue/aluminum foil/hot melt adhesive EVA.
Paper is a porous material that absorbs PU glue very strongly. Therefore, it is coated with the same rubber roller as the composite film. Since most of the glue is sucked into the porous paper, the amount of glue on the surface is not enough. Therefore, the composite fastness is greatly reduced, and the fastness to the composite with aluminum is poor. The solution is to first coat a layer of primer on the paper, which may be other resin glue, and then coat the PU after drying it. With compound glue, the fastness of compounding can be improved. It should be noted that the use of EVA hot melt adhesive in the inner layer of this structure is not suitable, even though EAV hot melt adhesive has a wide range of cup adaptability, namely: instant noodle bowls, whether using PP, PE, PS or PVC. The material is thermoformed, and the cover material can be heat-sealed on the bowl at a lower temperature by the hot melt adhesive with the inner layer of EVA, but the pure EVA hot melt adhesive without the easy agent is not It is easy to tear open and it is not easy to open. Materials that reduce the heat seal strength, such as surfactants, should be appropriately added to the EVA.
(1) When the 150g/m2 paper is extrusion coated, the temperature at 315 °C is still not strong enough to peel off. Why? How to deal with it? (Used LDPE particles, paper is white paper)
If it is ordinary paper, that is, paper which has not been treated with any polymer, it is applied by extrusion flow, and good adhesion is obtained without any primer or corona treatment. Since paper is a porous material, it is easy to bond with molten LDPE. On the contrary, if the paper has been pre-impregnated or pre-coated with a certain polymer, it should be corona treated, then coated with AC agent and Increase the LDPE temperature. Generally speaking, increasing the temperature of LDPE extrusion is advantageous for the fastness of extrusion coating. As long as it does not cause decomposition of LDPE, the decomposition temperature of LDPE is above 315 °C.
(2) The factory has two ternary co-extrusion compounding machines, which products can be developed and produced?
The co-extruded composite products that can be developed and produced are: the first can produce frozen food packaging film: PP/EVA/LDPE) Because PP has a good affinity with LDPE, it is not very good, so adding EVA is beneficial to PP and LDPE bonding. Increased fastness. The above structure can also be used for packaging of dry foods, such as biscuits, instant noodles, fried rice, etc., and the use of coextrusion compound is cheaper than the complex price, and is competitive. The second can produce milk packaging bags, LDPE is black, PP is white, this bag can be hot-filled at 80C, but it is a simple bag and can only be stored for about 3 days. Thirdly, it is possible to produce a wrap-around packaging film which is tacky on one side and not sticky on the other side.
(3) The current mustard bag packaging, widely used BOPP / reverse printing / DL / VMAICPP structure, this structure, often the reverse printing ink is glued together by PU adhesive, and peeled off BOPP, why?
The dry composite adhesive contains a large amount of ethyl acetate solvent, and ethyl acetate is an excellent solvent for the reverse printing ink binder. When the two-component polyurethane adhesive is coated on the reverse printing ink, the ethyl acetate in the rubber penetrates into the ink. In the middle, the ethyl acetate enters the printing surface of BOPP, causing loosening or even delamination of the bonded portion between the printing ink and the BOP, and the penetration of the ethyl acetate with the PU glue on the ink layer is improved. The bonding strength of the entire printing layer with the PU glue, the result is the original
The anti-printing ink with good adhesion is separated from the BOP film. The solution is to apply PU glue on the vacuum aluminum plated surface of VMAICP film, and after the drying process at 60-90 degrees Celsius, it is combined with the reverse printed NOPP film. Thus, when the reverse printing ink is in contact with the PU glue, the PU glue It has been dried by a drying tunnel, in which the ethyl acetate content has been largely volatilized, and no penetration of ethyl acetate into the reverse printing ink layer is caused, which affects the adhesion of the ink layer to BOPP. Simultaneously
Increasing the PU cement content (reducing the amount of ethyl acetate solvent), increasing the temperature of the drying tunnel, and increasing the time to stay in the drying tunnel (slowing the composite speed) can improve and prevent such delamination.
(4) When producing instant noodle cover materials, the paper is not easy to be composited with aluminum foil, and is also a PU two-component adhesive used. Why? The instant noodle cover material structure is PET/reverse printing/PU glue/paper/PU glue/aluminum foil/hot melt adhesive EVA.
Paper is a porous material that absorbs PU glue very strongly. Therefore, it is coated with the same rubber roller as the composite film. Since most of the glue is sucked into the porous paper, the amount of glue on the surface is not enough. Therefore, the composite fastness is greatly reduced, and the fastness to the composite with aluminum is poor. The solution is to first coat a layer of primer on the paper, which may be other resin glue, and then coat the PU after drying it. With compound glue, the fastness of compounding can be improved. It should be noted that the use of EVA hot melt adhesive in the inner layer of this structure is not suitable, even though EAV hot melt adhesive has a wide range of cup adaptability, namely: instant noodle bowls, whether using PP, PE, PS or PVC. The material is thermoformed, and the cover material can be heat-sealed on the bowl at a lower temperature by the hot melt adhesive with the inner layer of EVA, but the pure EVA hot melt adhesive without the easy agent is not It is easy to tear open and it is not easy to open. Materials that reduce the heat seal strength, such as surfactants, should be appropriately added to the EVA.
Author：admin