Solvent-free laminating glue: problems in using solvent-free glue
Solvent-free laminating adhesive manufacturers said that the solvent-free adhesive will not volatilize VOCs, nor will it produce any irritating odor. At the same time, the problem of solvent residue in composite packaging is solved, the erosion of organic solvents on ink is eliminated, and clean production can be realized, which is conducive to environmental protection. Solvent-free composite equipment does not require a drying channel, reducing energy consumption. Moreover, in the later curing process, the curing temperature of solvent-free composite is basically the same as that of dry composite, so the energy consumption is relatively close.
Solvent-free laminating adhesiveThe manufacturer said that the solvent-free adhesive will not volatilize VOCs and will not produce any pungent odor. At the same time, the problem of solvent residue in composite packaging is solved, the erosion of organic solvents on ink is eliminated, and clean production can be realized, which is conducive to environmental protection. Solvent-free composite equipment does not require a drying channel, reducing energy consumption. Moreover, in the later curing process, the curing temperature of solvent-free composite is basically the same as that of dry composite, so the energy consumption is relatively close.
Solvent-free glue does not contain organic solvents, so there is no hidden danger of fire and explosion during production, transportation, storage and use, no explosion-proof and heat preservation measures, and no special warehouse for storing solvents. More importantly, there is no harm to the health of the operator. The speed of compounding with solvent-free adhesive is generally 250~350 m/min, and even 400~500 m/min; the speed of compounding with solvent-based adhesive is generally 150~180 m/min. The speed of compounding with water-based adhesives is low.
General flexible packaging compound with solvent-free glue mainly has the following problems:
1. It has a great influence on the smoothness of PE film. Solvent-free composite film manufacturers said that when the curing temperature of solvent-free composite materials is higher than 40, the solvent-free composite film with PE film as the inner layer (especially PE film with a thickness of less than 45m) will be greatly affected and the friction coefficient will increase significantly. This is mainly because the higher the curing temperature, the more intense the molecular movement of the slip agent in the PE film, which is easy to migrate to the adhesive layer and react with it and be consumed, resulting in an increase in the friction coefficient of the composite film.
2. Transfer of aluminized layer. Aluminized film, especially polyester aluminized film (VMPET), is prone to aluminized transfer during solvent-free compounding, resulting in insufficient peel strength of the composite film.
3. Dissolve with ink. In the solvent-free compounding process, sometimes the binder and ink, especially the dye-based ink, are dissolved.
At present, the solvent-free glue used in cooking packaging has the following problems:
1. Poor temperature resistance. Solvent-free laminating glue manufacturers said that most cooking packages require cooking at 121 degrees for 40 minutes. This is because the sterilization temperature of many flexible packaging enterprises is controlled at 118~120. Therefore, if the temperature does not exceed 121, the solvent-free adhesive that can be cooked with 121 will not have quality problems. And some flexible packaging enterprises strictly control the sterilization temperature in 121 or even greater than 121 sterilization to ensure product quality, which requires cooking solvent-free glue to withstand 125 or even higher temperatures to ensure that composite products will not have quality problems.
2. Mix ink. Solvent-free laminating glue manufacturers indicate that when solvent-free cooking glue is applied to transparent cooking packaging, there is generally no lamination of the composite film. However, when the solvent-free glue is poorly matched with the ink, the peel strength of the ink is significantly lower than that of the transparent part and other colored inks, and the ink is more likely to be layered after cooking.
3. The peel strength of aluminum foil composite is low. Solvent-free glue is still the bottleneck that aluminum foil solvent-free compounding needs to break through, because its peel strength is not enough to meet the requirements of heavy packaging and retort resistance. Technicists often add adhesion promoters to the adhesive formulation to effectively increase the adhesion to the aluminum foil and improve the peel strength.
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