Sakata Inx develops New generation high density coldset inks
Sakata Inx works with newspaper printers to create value and responds to social demand for environmental issues. They have developed High Density Ink, which will give newspapers total cost advantage with higher quality.
Development of high density ink started at Sakata Inx Corporation Japan in 2004 as there were many 4-colour tower high speed machines installed and customers wanted improvement in printing quality on high speed machines.
Another reason to develop this was increased focus on global warming. Therefore customers in Japan demanded to use materials which have low load on environment. They started promoting newspaper coldset web printing rather than heatset where high energy is required for heating and cooling systems. Also this high density ink reduces consumption as less ink thickness is required to print same optical density.
Since heatset papers are normally coated and require fast drying of ink, normal coldset ink does not dries on such coated paper, which results in various printing problems like set-off, smugging, rub off etc. This was one of the challenge while developing HD inks.
As shown in Figure 1, newspaper are rough and highly porous in structure, therefore it is easy for normal ink to dry on this paper by penetration but on coated paper which has smooth surface & low porosity , same ink takes very long time to dry.
Though high absorbency of newsprint papers helps in fast drying by penetration but it also leads to higher density drop in printing.
As shown in Figure 2, the penetration of ink occurs soon after printing and this penetration involves degradation of optical density because pigment also penetrates inside the paper. Then after drying, less pigment remains on surface. However heatset ink on coated paper dries immediately after passing through heater, so ink penetration is very less, which results in higher density.
As shown in Figure 3, due to dry down in newsprint, it is difficult to get very high density even with high ink thickness. Therefore if high density is required with conventional ink, very high ink thickness is required, which means high ink consumption.
Development of High Density Ink:
As shown in Figure 4, High density inks contains high pigment and less fillers. However high pigmentation leads to high viscosity and short flow in ink which results in poor ink transfer on various news printing machines.
High pigment loading also leads to re-agglomeration of pigment in ink which results in poor grinding, loss of strength and density & poor flow (Fig 5).
To tackle these challenges, Sakata uses a specially designed dispersion additive and resin system which gives very good and stable dispersion in Ink. Also this new generation additives helps to maintain good emulsification and flow during printing (Fig6).
These new generation raw materials used in this ink gives excellent ink transfer on rollers even with less ink thickness. Also it gives excellent stable density even at high speed (Fig7).
Advantages of High Density Ink:
Standard Density Printing
Reduced ink consumption
- Reduced fountain solution and water
- Reduced strike through
->light weight paper (Fig 8)
- Low dot gain & excellent dot reproduction (Fig 9 & 10)
- Improve set off (Fig 11)
- Low misting
- Reduce start up paper waste
High Density Printing
Support High Coverage Image->Improve Customer Satisfaction
- Non Heat Printing for Uncoated to Glossy Coated
- Maximize Performance with High Definition
- Maximize Press Usage
- Cost Reduction by Non Heat Printing CO2 Reduction
- Reduced ink inventory
- Reduced newspaper transportation load (light weight paper)
- Reduced ink transportation load
With above advantages, it also possible to do high quality printing on semi-coated papers with heatset machine without using dryer.