Development of SAKATA INX’s new generation high density cold set ink
SAKATA INX Corporation Japan started development of high density ink in 2004 as there were many 4-colour tower high speed machines installed around the country and the customers demanded improve printing quality on high speed machines. Another reason to develop the ink was the increase focus on global warming.
As an increasing concern over global warming customers in Japan asked for materials and technologies which have low load on environment, like promotion of newspaper cold set web printing rather than heat set where high energy is required for heater and cooling system. In this, SAKATA INX’s high density ink reduces consumption as it takes less ink thickness to print same optical density.
Since heat set papers are normally coated and require fast drying of ink, normal cold set ink does not dry on such materials which in turn results in various printing problems like set-off, smudging, rub off, etc. This was one of the challenges of SAKATA INX while developing the high density ink.
As shown in the figure captioned ‘Micro photography of paper’ newsprint is 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 and low porosity, same ink takes very long time to dry. Though high absorbency of newsprint helps in fast drying by penetration it also leads to higher density drop in printing.
Now look at the figure with caption ‘Penetration of ink’, 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 dry, less pigment remains on the surface. However, heat set ink on coated paper dries immediately after passing through heater, so ink penetration is very less.
As shown in the figure captioned ‘Ink thickness & density relation’, 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 the figure with caption ‘Ink formula comparison’, high density inks contain high pigment and less filler. 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 and poor flow as illustratively shown in the figure captioned ‘Pigment dispersion’. To tackle these challenges, SAKATA INX uses a specially designed dispersion additive and resin system which gives good and stable dispersion in ink. Also, this new generation additives help maintain good emulsification and flow during printing as shown in the figure captioned ‘Emulsification and flow during printing’.
These new generation raw materials used in SAKATA INX’s high density ink gives excellent ink transfer on rollers even with less ink thickness. In addition, it gives excellent stable density even at high speed as shown in the figure captioned ‘Density stability & speed’.
ADVANTAGES OF HIGH DENSITY INK
Standard density printing
- Reduces ink consumption
- Reduces fountain solution and water
- Reduces strike through -> light weight paper as shown in the figure captioned ‘Reduces strike through’.
- Low dot gain & excellent dot re production as shown in the figures captioned ‘Minimises dot grain’ and ‘Good dot reproduction even if printing at high density’.
- Improves set off as shown in the figure captioned ‘Gives very low set-off’
- Low misting
- Reduces start up paper waste
As shown in the figure with caption ‘Reduces strike through’ low gsm newsprint (40/42 gsm) tends to give more strike through but with high density ink strike through can be minimised due to low ink thickness to maintain same standard density.
SAKATA INX’s high density ink can minimise dot gain as low ink thickness and less water require to get same standard density, as shown in the figure captioned ‘Minimises dot grain’.
High density printing
- Supports high coverage image improves customer satisfaction
- Non-heat printing for uncoated to glossy coated papers
- Maximises performance with high definition
- Maximises press usage
- Cost reduction by non-heat printing CO2 reduction
- Reduces ink inventory
- Reduces newspaper transportation load (light weight paper)
- Reduces ink transportation load
With the above advantages it also possible to do high quality printing with SAKATA INX’s new generation high density cold set ink on semi-coated papers with heat set machine without using drier.
SAKATA INX works with newspaper printers to create value and responds social demand for environmental issue. The company’s high density ink will give newspaper total cost advantage with higher quality.