10 likes | 121 Views
ACTEGA Kelstar Technical Bulletin Alcohol Free Dampening Solutions.
E N D
ACTEGA Kelstar Technical BulletinAlcohol Free Dampening Solutions • In recent years to improve air quality, printers have had to reduce their Volatile Organic Compounds (VOC) emissions. The first major area of reduction was eliminating the use of isopropyl alcohol in dampening solutions. The function of isopropyl alcohol in the dampening system is to improve the rheological properties of the ink and promote faster ink setting and drying. • The advent of alcohol substitutes replacing isopropyl alcohol has resulted in specific problems on press and at UV finishing houses. After the sheets are printed and the aqueous primer is applied, the ink becomes sealed beneath the primer. The emulsified ink and the alcohol substitutes which have a high vapor pressure are then trapped which significantly slows the drying of the ink, requiring two to three times the normal drying time. • When UV coating is applied over wet inks, or inks that have not properly dried, poor intercoating adhesion will result between ink, primer and UV coating. The glycols and glycol ethers that are used in alcohol substitutes act as plasticizers, softening both the ink and the UV coating, resulting in unacceptable adhesion. To minimize adhesion problems, pressmen should run with the lowest water settings possible and use fountain solutions which contain minimal levels of glycol and glycol ethers. The selection of the aqueous primer will greatly affect adhesion with the UV coating. • The printer and converter must allow a greater time interval between printing and coating. Incoming jobs should be examined to determine wet or soft inks, and sample sheets should be coated. If poor intercoating adhesion results then the sheets should sit an additional 24 hours before being coated. • Although the EPA’s requirement for dampening solution substitution was well intended, it has caused nationwide / industry-wide problems that can be easily resolved with cooperation and ample lead times between printers and converters. • Contact ACTEGA Kelstar at 856 829 6300 or info.actega.kelstar@altana.com for additional information or technical assistance.