Problems and solutions for general-purpose solvent-free adhesives
Problem
(1) Great influence on the smoothness of PE film
When the solvent-free composite curing temperature is greater than 40 ° C, the effect of the solvent-free composite film on the inner layer of PE film (especially the structure of PE film thickness < 45 μm) is large, and the phenomenon that the friction coefficient is obviously increased is prone to occur. This is mainly because the higher the curing temperature, the more intense the molecular motion of the slip agent in the PE film, and it is easy to migrate to the adhesive layer and react with it to be consumed, eventually leading to an increase in the friction coefficient of the composite film.
(2) Aluminized layer transfer
Aluminized film, especially polyester aluminized film (VMPET), is prone to aluminum transfer during solventless compounding, resulting in insufficient peel strength of the composite film.
(3) Dissolving with the ink phase
In the solventless compounding process, the phenomenon that the adhesive and the ink phase are dissolved sometimes occurs, especially the dye type ink.
solution
In response to the above problems, the “1†low-friction coefficient solvent-free adhesive recently developed by Kangda New Materials can greatly improve the smoothness of PE film and the transfer of aluminized layer, and the matching with ink has also been greatly improved. Table 1 compares the friction coefficients of composite films using common solvent-free adhesives and “1†low-friction coefficient solvent-free adhesives.
Problems and solutions for cooking-type solvent-free adhesives
Problem
(1) poor temperature resistance
Most cooking packages require cooking at 121 ° C for 40 minutes. This is because many flexible packaging companies control the sterilization temperature at 118-120 ° C, so the highest temperature does not exceed 121 ° C, the use of 121 ° C cooking solvent-free adhesive will not have quality problems. However, some flexible packaging companies strictly control the sterilization temperature at 121 ° C, or to ensure product quality and even sterilize according to conditions greater than 121 ° C, which requires that the cooking-type solvent-free adhesive can withstand temperatures of 125 ° C or higher. Ensure that quality problems do not occur with composite products.
(2) Matching problem with ink
When the cooking-type solvent-free adhesive is applied to the transparent cooking package, the delamination of the composite film generally does not occur. However, when the solvent-free adhesive is poorly matched with the ink, the peel strength at the ink is significantly lower than that at the transparent portion and other inks, and the ink is more likely to be delaminated after cooking. phenomenon.
solution
Kangda's new “5†solvent-free adhesive introduces new high-temperature resistant groups, which has changed the way of improving the resistance to cooking of solvent-free adhesives by adding high-temperature resistant polyester. This series of cooking-type solvent-free adhesives not only has a greater cost advantage than the original retort-type products, but also greatly improves the cooking performance of the solvent-free adhesive and the matching with the ink.
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