• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 2006.06b
• /
• pp.209-213
• /
• 2006

Relationship between printability and rheological properties of UV flexographic (flexo) inks were investigated. UV flexo suspensions of carbon black in liquid medium having various binding materials such as acylate pre-polymer, di/multi-functional monomer, and diluents, were used as sample inks. Inks were characterized on a rheometer in terms of steady and dynamic behaviors. To understand the rheological properties of UV flexo inks, we must determine the specific rheological properties of chemical and/or physical interactions of their components (pigments, functional monomers, and pre-polymers). In particular, we discussed the influence of multi-functional monomers and the relationship between the rheological properties and transient networks formed by carbon black. In this study, we investigated the interrelationships between rheological properties of UV flexo inks and chemical and/or physical interactions of their components. To investigate correlations between the printability and the rheological behaviors induced by interfacial interactions between ink compositions, we carried out rheological tests of UV ink suspensions. The results were compared with printing tests so as to find out the relationship between printability and rheological properties of ink.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.35 no.5
• /
• pp.10-16
• /
• 2003

Presence of small amount of old newspapers printed with waterbased flexographic inks leads to a significant loss of brightness of the deinked pulp by flotation process. Recently there has been an increased interests in employing neutral deinking processes to solve the problems associated with waterbased flexo ink. A comparative experimental study was performed to evaluate the efficiency of neutral deinking and conventional alkaline deinking for ONP furnishes contaminated with flexo ink. Effects of the deinking processes on pulp quality and white water characteristics were examined. It was shown that neutral deinking would provide significant improvement in brightness, yield, and freeness as compared with conventional alkaline deinking. There was no increase in brightness when OMG was added in the furnish up to 20 ％, and it was attributed to the redeposition of flexo inks on chemical pulp fibers.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
• /
• 1999.04b
• /
• pp.343-348
• /
• 1999

Presence of small amount of old newspapers printed with waterbased flexographic inks leads to a significant loss of brightness of the deinked pulp by flotation process. Recently there has been an increased interests in employing neutral deinking processes to solve the problems associated with waterbased flexo ink. A comparative experimental study was performed to evaluate the efficiency of neutral deinking and conventional alkaline deinking for ONP furnishes contaminated with flexo ink. Effects of the deinking processes on pulp quality and white water characteristics were examined. It was shown that neutral deinking would provide significant improvement in brightness, yield, and freeness as compared with conventional alkaline deinking. Three was no increase change in brightness when OMG was added in the furnish up to 20%, and it was attributed to the redeposition of flexo inks on chemical pulp fibers.

• The monthly packaging world
• /
• s.293
• /
• pp.83-89
• /
• 2017

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.38 no.4 s.117
• /
• pp.31-40
• /
• 2006

Presence of old newspapers printed with waterbased flexographic inks leads to a significant loss of brightness of the deinked pulp by flotation process. It has been shown that neutral or acidic flotation deinking has many advantages in recycling of flexo printed newsprints. A comparative experimental study was performed to evaluate the deinking efficiency of three alcohol type deinking agents in flotation deinking of flexo printed newspapers. Zeta potential of neutral deinked pulp was less negative than alkaline deinked pulp. Also neutral deinking was advantages in reducing turbidity, COD, and cationic de-mands of deinking process water.

• Journal of Korean Society on Water Environment
• /
• v.22 no.6
• /
• pp.996-1003
• /
• 2006

The absorption characteristics of powdered activated carbon doped by transition-metal nanoparticles were investigated to enhance the remove efficiencies of $TCOD_{Mn}$ and Color from the flexo-inks wastewater. According to the adsorption dynamics of PAC and MPAC, the optimal dosage of activated-carbon adsorbents was 3 g/L under the reaction conditions of pH6.0, 30 mill of reaction time, 240 rpm of mixing intensity. The removal efficiencies by the optimal dosages were maximized as 19% $TCOD_{Mn}$, 57% Color for PAC and 88% $TCOD_{Mn}$, 95% Color for MPAC. Freundlich indexes of isotherm absorption were estimated as follows: i) For PAC, k=-8.11, 1/n=2.98, r=0.91 in the raw water, and k=0.14, b/n=0.75, r=0.96 in the biological treatment water, ii) For MPAC, k=2.69, 1/n=0.21, r=0.80 in the raw water, and k=0.74, 1/n=1.17, r=0.95 in the biological treatment water. MPAC (Powdered activated carbon doped by transition-metal nanoaprticles) was very effective in the removal of organics from the raw water and biological treatment water, as Freundlich indexes of 1/n for both types of water were estimated less than 2.0.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.33 no.1
• /
• pp.8-15
• /
• 2001

Presence of small amount of old newsprints printed with waterbased flexographic inks leads to a significant loss brightness of the deinked pulp by flotation process. Recently there has been an increased interest in employing neutral deinking processes to solve the problems associated with waterbased flexo ink. A comparative experimental study was performed to evaluate the efficiency of neutral deinking and conventional alkaline deinking for ONP furnishes contaminated with flexo ink. It was shown that neutral deinking provides significant improvements in brightness, yield and freeness as compared with alkaline deinking. Flotation efficiency was different depending upon the type of surfactants used in neutral deinking. The result of this study showed that alcohol type surfactant is superior to fatty acid type surfactant in neutral deinking efficiency.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.9
• /
• pp.7-10
• /
• 2010

Recently, roll-to-roll printers are being developed actively by various research teams such as research institutes, universities and companies for the application of printed electronics. The printing methods that are widely used in the roll-to-roll printing equipments are gravure, gravure and flexo, which depend on the inks used and electronic devices produced. In general, a single printing unit of roll-to-roll printing equipment adopts only one printing method and this method is not changeable, which limits the application fields of the developed printing equipments. In this paper, the roll-to-roll printer, in which the printing unit has the novel design concept, is described.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.44 no.5
• /
• pp.8-13
• /
• 2012

The flexography ink has disadvantage in a deinking process because it tends to form too fine particles in alkali condition to be removed in flotation deinking. The influence of pH conditions on the particle size of phthalocyanine cyan ink used for flexo-printing was investigated to see the effect of pH conditions on flexography ink dispersion. Flexography ink particles prepared by grinding dried ink films were used in this experiment. Greater reduction of the ink particle size was noticed under alkaline pH condition, which was attributed to dissolution of resin component of the ink. Adsorption behavior of flexography ink onto pigment particles was examined using clay and talc as substrate pigments. Pretreatment of inorganic pigments with a cationic poly-DADMAC increased the surface adsorption of flexography ink particles, which improved the removal of the inks by centrifugal sedimentation of inorganic pigments. Most efficient removal of the ink particles was achieved when an optimal addition level of the cationic polymer was used for pretreatment of inorganic pigments, and this optimal addition level corresponds to the surface saturation point of the polyelectrolyte. Adsorption of flexography ink particles onto inorganic pigments improved the ink removal in flotation deinking since the pigment particles has the optimal particle size for flotation deinking.