UVgel technology
In the previous post, we already mentioned our new UVgel printing technology. Today we offer to talk more about its specifics and the prerequisites of occurrence.
But first, let's move away a bit from the topic and find out what is happening in the wide format printing market.
In the future, until 2020, a number of research marketing companies forecast annual growth of printing volumes by an average of 3%. It is expected that the main part will be on signs, banners, posters and, of course, packaging products. But besides the increase in printing volumes, the rhythm of modern business requires minimization of the terms of execution of orders. According to the InfoTrends study, the real demand for print terms was distributed as follows:
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We see that the bulk of orders accounted for printing, completed as soon as possible. This means that the winner will be the company that will be able to offer the most expeditious performance of services with other things being equal. The applied printing equipment plays a significant role in this.
Two types of printing are traditionally used today:
The most common is the first form. This is due to the relatively low cost of equipment and ease of maintenance. However, obtaining satisfactory results, due to the technology used, is a constant compromise between quality and performance. In addition, this equipment works with a limited range of materials due to the presence of high-temperature processes during printing.
One of the ways to increase productivity is to expand the fleet of equipment, which requires additional production space and staff expansion. This is justified only during periods of peak loads and unprofitable during periods of recessions.
Printing with UV-curable inks is of good quality with high productivity. But its widespread use is limited due to serious initial investments, which often prove to be very heavy for small and medium-sized companies. However, even the possession of such equipment must be ensured by a continuous flow of orders in large volumes, so that the investment remains in the profitability zone.
Thus, the segment of large format printing has two extreme positions. On the one hand, low start-up investments with low productivity or quality, and on the other - good quality and speed, but at a high cost. The new UVgel technology is focused on occupying an empty niche and giving high print quality with relatively small investments.
Consider the main problems affecting the speed and quality of printing. Since we accept printing with UV-curable inks as a kind of reference, we will consider printing with latex and eco-solvent inks. It has a number of weaknesses associated with the feature of the technology. That is, it is impossible to completely get rid of the shortcomings, but the modernization does not give the desired results. Of the main drawbacks, we highlight:
Let us dwell on each in more detail.
The difference in the area of printed elements between the digital file and the finished print is called Dot Gain. In the domestic printing industry, this term corresponds to the term "spreading". This phenomenon is based on several components:
The foundation
Each material used as a base has individual characteristics. These include:
The first three characteristics give an optical spreading, which will appear invariably with any type of printing. Due to the spread of light in the layer of the carrier in its depth, a shadow is created from the contours of the print. At the same time, the print size is perceived more visually than it actually is.
From the porosity of the base depends on the depth and area of penetration of paint. This parameter is closely related to the physicomechanical properties of the ink.
Ink
The main contribution to the phenomenon of spreading falls on the share of ink. Here density, adhesive properties, fixing time, transparency and many other things matter. When printing, adjustments are made to the equipment to compensate for the spreading. But this does not always give the desired effect.
In some cases, fingerprint repeatability is key. For example, when printing wallpaper, when prints made at different times are in direct contact. The quality of such printing is possible to realize, but this is achieved by a significant reduction in speed. So on a latex printer with maximum quality performance drops to 6 m2 / h. It is clear that large volumes of high-quality printing on equipment of this type cannot be done in a short time.
Feed and processing mode of the sealed material
To a lesser extent, but still affects the spreading rate of feed and drying basis. This affects the shape of the drop print and the degree of ink flow.
Consolidation of latex and ecosolvent inks occurs under the influence of temperature due to evaporation of the solvent (solvent). Drying prints occurs at relatively high temperatures. Because of this, the range of materials used as the basis is limited. When latex and eco-solvent printing can not be used thermoplastic materials.
Taking into account the nuances described above, a new technology UVgel was developed. Simplified printing process can be described in the following stages:
What kind of printing problems does UVgel solve? Liquid ink, leaving a printing head, turn in gel directly on the carrier. They immediately form a point, without spreading over the surface. The size and positioning of the points are fixed, and the merging and mixing of neighboring points is completely eliminated. Thus, we can control the mechanical spreading with high precision - and this gives an additional plus.
When printing with latex and ecosolvent inks in order to reduce spreading, a one-time ink supply is reduced, but the number of passes of the print head increases, which significantly reduces equipment performance. UVgel technology allows you to apply the maximum amount of ink in one pass, without reducing the quality of the print. That is, we have eliminated the dependence of printing speed on this factor.
It should be noted that our new technology has a predominant difference from traditional UV printing. This concerns the quality of the surface when sealing. So, with UV printing in several passes, each ink layer is dried immediately after printing due to the fact that UV curing lamps move with the print head. As a result, a micro-relief is formed on the surface of the print. In UVgel technology, this process proceeds somewhat differently. The gel-like state of the ink does not require instant curing. There is a small time interval between the moment of their application and UV exposure. During this time, a drop of ink gel has time to settle, and the surface tension force - to form its smooth surface. Only after that the applied ink is cured by UV light. There is no fundamental difference between these two types of surface, but a smoother one perceives the subsequent lamination better.
UVgel technology has the added advantage of ink composition. When curing the imprint, there is no need for temperature evaporation of the solvent. In addition, the technology requires printing at a stable temperature of +28 0C. And this allows you to significantly expand the range of materials used as the basis. This applies particularly to thermoplastic materials that cannot be used for latex and eco-solvent printing. Also, when using materials with high porosity and high absorbency, this technology will not impair the quality of the print. Unlike latex and ecosolvent inks, which are absorbed and spread until they are completely dry, UVgel inks are simply glued to the surface, forming stable dots.
Today, the technology is implemented in a large-format printer Océ Colorado 1640 - the first roll printer of this type. In our next reviews, we will definitely tell about the characteristics of the machine and the hardware solutions used to implement the UVgel technology - watch for updates so as not to miss.
But first, let's move away a bit from the topic and find out what is happening in the wide format printing market.
The modern market of large format printing: trends and problems
In the future, until 2020, a number of research marketing companies forecast annual growth of printing volumes by an average of 3%. It is expected that the main part will be on signs, banners, posters and, of course, packaging products. But besides the increase in printing volumes, the rhythm of modern business requires minimization of the terms of execution of orders. According to the InfoTrends study, the real demand for print terms was distributed as follows:
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- fulfillment of the order during the day - 41%
- from one day to two - 21%
- more than two days - 38%.
We see that the bulk of orders accounted for printing, completed as soon as possible. This means that the winner will be the company that will be able to offer the most expeditious performance of services with other things being equal. The applied printing equipment plays a significant role in this.
Two types of printing are traditionally used today:
- with latex or ecosolvent inks;
- with UV curable inks.
The most common is the first form. This is due to the relatively low cost of equipment and ease of maintenance. However, obtaining satisfactory results, due to the technology used, is a constant compromise between quality and performance. In addition, this equipment works with a limited range of materials due to the presence of high-temperature processes during printing.
One of the ways to increase productivity is to expand the fleet of equipment, which requires additional production space and staff expansion. This is justified only during periods of peak loads and unprofitable during periods of recessions.
Printing with UV-curable inks is of good quality with high productivity. But its widespread use is limited due to serious initial investments, which often prove to be very heavy for small and medium-sized companies. However, even the possession of such equipment must be ensured by a continuous flow of orders in large volumes, so that the investment remains in the profitability zone.
Thus, the segment of large format printing has two extreme positions. On the one hand, low start-up investments with low productivity or quality, and on the other - good quality and speed, but at a high cost. The new UVgel technology is focused on occupying an empty niche and giving high print quality with relatively small investments.
Printing Problems of Large Format Printing Machines
Consider the main problems affecting the speed and quality of printing. Since we accept printing with UV-curable inks as a kind of reference, we will consider printing with latex and eco-solvent inks. It has a number of weaknesses associated with the feature of the technology. That is, it is impossible to completely get rid of the shortcomings, but the modernization does not give the desired results. Of the main drawbacks, we highlight:
- the phenomenon of Dot Gain or spreading;
- thermal drying print.
Let us dwell on each in more detail.
Spreading
The difference in the area of printed elements between the digital file and the finished print is called Dot Gain. In the domestic printing industry, this term corresponds to the term "spreading". This phenomenon is based on several components:
- optical and diffusion properties of the base;
- physicomechanical and optical properties of ink;
- the mode of submission and processing of the printed base;
- dimensions and shape of print elements.
The foundation
Each material used as a base has individual characteristics. These include:
- Colour;
- light reflecting ability;
- transparency;
- porosity and more.
The first three characteristics give an optical spreading, which will appear invariably with any type of printing. Due to the spread of light in the layer of the carrier in its depth, a shadow is created from the contours of the print. At the same time, the print size is perceived more visually than it actually is.
From the porosity of the base depends on the depth and area of penetration of paint. This parameter is closely related to the physicomechanical properties of the ink.
Ink
The main contribution to the phenomenon of spreading falls on the share of ink. Here density, adhesive properties, fixing time, transparency and many other things matter. When printing, adjustments are made to the equipment to compensate for the spreading. But this does not always give the desired effect.
In some cases, fingerprint repeatability is key. For example, when printing wallpaper, when prints made at different times are in direct contact. The quality of such printing is possible to realize, but this is achieved by a significant reduction in speed. So on a latex printer with maximum quality performance drops to 6 m2 / h. It is clear that large volumes of high-quality printing on equipment of this type cannot be done in a short time.
Feed and processing mode of the sealed material
To a lesser extent, but still affects the spreading rate of feed and drying basis. This affects the shape of the drop print and the degree of ink flow.
Heat drying
Consolidation of latex and ecosolvent inks occurs under the influence of temperature due to evaporation of the solvent (solvent). Drying prints occurs at relatively high temperatures. Because of this, the range of materials used as the basis is limited. When latex and eco-solvent printing can not be used thermoplastic materials.
UVgel printing technology: features and benefits
Taking into account the nuances described above, a new technology UVgel was developed. Simplified printing process can be described in the following stages:
- Warming up UVgel-ink in the print head to transfer them from a gel to a liquid state.
- Putting ink on the media, the temperature of which is automatically maintained at +28 0C.
- By maintaining the set temperature, the ink, once on the media, instantly turns from liquid to gel.
- In a gel-like state, the drops are immediately fixed on the carrier and do not spread.
- After applying ink to the media, they are cured by LED UV illumination.
What kind of printing problems does UVgel solve? Liquid ink, leaving a printing head, turn in gel directly on the carrier. They immediately form a point, without spreading over the surface. The size and positioning of the points are fixed, and the merging and mixing of neighboring points is completely eliminated. Thus, we can control the mechanical spreading with high precision - and this gives an additional plus.
When printing with latex and ecosolvent inks in order to reduce spreading, a one-time ink supply is reduced, but the number of passes of the print head increases, which significantly reduces equipment performance. UVgel technology allows you to apply the maximum amount of ink in one pass, without reducing the quality of the print. That is, we have eliminated the dependence of printing speed on this factor.
It should be noted that our new technology has a predominant difference from traditional UV printing. This concerns the quality of the surface when sealing. So, with UV printing in several passes, each ink layer is dried immediately after printing due to the fact that UV curing lamps move with the print head. As a result, a micro-relief is formed on the surface of the print. In UVgel technology, this process proceeds somewhat differently. The gel-like state of the ink does not require instant curing. There is a small time interval between the moment of their application and UV exposure. During this time, a drop of ink gel has time to settle, and the surface tension force - to form its smooth surface. Only after that the applied ink is cured by UV light. There is no fundamental difference between these two types of surface, but a smoother one perceives the subsequent lamination better.
UVgel technology has the added advantage of ink composition. When curing the imprint, there is no need for temperature evaporation of the solvent. In addition, the technology requires printing at a stable temperature of +28 0C. And this allows you to significantly expand the range of materials used as the basis. This applies particularly to thermoplastic materials that cannot be used for latex and eco-solvent printing. Also, when using materials with high porosity and high absorbency, this technology will not impair the quality of the print. Unlike latex and ecosolvent inks, which are absorbed and spread until they are completely dry, UVgel inks are simply glued to the surface, forming stable dots.
Today, the technology is implemented in a large-format printer Océ Colorado 1640 - the first roll printer of this type. In our next reviews, we will definitely tell about the characteristics of the machine and the hardware solutions used to implement the UVgel technology - watch for updates so as not to miss.
Source: https://habr.com/ru/post/374315/
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