Discussion on Solvent Residual Problems of Dry Composite Color Printing Composite Film

The influence of water content in ethyl ester The water content in ethyl ester not only affects the peel strength, transparency, etc., but also has a greater impact on the volatilization of ethyl ester, which in turn affects the residual solvent content of the composite membrane, which is still a More difficult problems, at present there is no national standard for soft packaging ethyl ester standards. When Henkel enters China, it clearly puts forward the concept of “urethane grade” ethyl ester, and clearly specifies its standards, ie, the water content is less than 300ppm, the alcohol content is less than 200ppm, and the concentration is higher than 99.9%. If such a standard is adopted, domestically The production of most enterprises may not be able to proceed normally. Most soft packaging companies in China rely on the national standards provided by production companies for acceptance. There is a more serious problem here. Relevant departments should, in accordance with the requirements of domestic flexible packaging companies, product quality requirements, product quality requirements, and considering the quality level of domestic ethyl esters, effectively put forward a more reasonable use standard to guide the production of flexible packaging. For the same reason, the humidity of workshops will also be high. The final composite membrane solvent residue is increased.
Impact of Adhesive Structures Experienced companies have this understanding that adhesives from different manufacturers' composite membranes produced by the same material and under the same process are not the same. This is because the main agent of the polyurethane adhesive contains hydroxyl (-OH) in the molecular bond of the active hydrogen, and hydrogen bonds with the ethyl ester (CH2CH2OCH2CH2). This hydrogen bond, the formation of this hydrogen bond, greatly binds Ethyl ether was volatilized. The change in the structure of the main agent will affect the strength of this hydrogen bond. The stronger the hydrogen bond, the more difficult the release of ethyl ester, and thus the different main agents will result in different solvent residues. At the end of 2001, Gaomeng Co., Ltd. developed and successfully developed a low-residual aluminized film compounding special glue. Based on the original YH50S, it also increased the performance of low-solvent residuals, and can be adapted to packs requiring low residual solvent for bulking.
The influence of the ink is composed of four parts: the binder, the solvent, the pigment and the modifier. Among them, the part of the binder that affects the residual amount of the solvent is larger, and the rate of volatilization of different binders to the same solvent is The effect is different. For example, PET printing uses polyester PET as the bonding material. The hydroxyl (-OH) group in the molecule will form a weak hydrogen bond with ethyl ester (CH2CH2OCH2CH3), thus inhibiting the B. The release of esters, such as BOPP printing using chlorinated polypropylene resin as binder for BOPP inks, has an impact on the release of toluene, because of this, chlorinated polypropylene and toluene contain strong polar groups, and The ester solubility parameters are similar and a strong intermolecular force is formed. This is an important microscopic reason why BOPP printing products tend to exceed the standard. (Text/Deng Yidong) (China Packaging Newspaper and Printing Weekly)