Newspaper Printing and Purple Laser CtP Technology

Drupa 2000 has a new CtP technology called the violet laser diode. There were two very different opinions on this technology at the time. One considers this technology to be a major breakthrough, while the other considers it to be irrelevant and in conflict with the existing CtP technology.

By the time of Drupa 2004, violet lasers had become the main force of CtP, and all major media manufacturers already had violet laser plates or were planning to produce them immediately. Almost all mainstream manufacturers of platemaking machines have violet laser equipment. These plates and platesetters are suitable for printing plants of various types, formats, and fields. The question faced by newspaper printing is which CtP technology to use for them, and why. To answer this question, we must consider various technical options and how these technical options meet the requirements of modern newspaper manufacturers.

Technical choice

Today's CtP technology is mainly divided into two types: thermal and violet lasers. In the field of commercial printing, thermal sensitivity has been widely recognized. Violet lasers have also been successful in the business and newspaper industry. Both technologies have their own characteristics and advantages.

1, thermal

Thermally used diodes with a wavelength of 830 nm, the plate coating absorbs laser energy and then uses heat to form images on the plate. Thermal CtP has the following three significant features:

Can be baked to improve print durability
Manual operating system can provide bright room operation
Can provide high resolution

2, violet laser

Violet lasers use diodes with a wavelength of 405 nm. The plate coating absorbs laser energy and forms an image on the plate—the plate coating is usually a photopolymer or silver salt coating. Purple laser CtP has the following three significant features:

Due to the extremely reliable violet laser diodes, the life expectancy is longer than that of the platesetter, so no replacement is required;
Low prices and low operating costs
Can provide high resolution

The practical significance of various advantages

The advantages of thermal technology are very important to some commercial printers. However, in the newspaper industry, heat has only 15% or even less share. The reason is that the above advantages of thermal technology are not as valuable to the newspaper industry as it is to commercial printing. Thermal technology was developed for commercial printing of CtP, so it certainly has characteristics that fit this market. However, few newspaper printers require manual CtP. They also do not need baking or printing at 300 LPI.

But the low cost of violet lasers is attractive to any type of printer, and the incredible reliability of violet laser diodes has also won popularity. Newspapers are particularly welcome for reliability, and they demand higher and faster requirements for platesetters. Because many plate-making machine manufacturers believe that the lifespan of violet laser diodes will be longer than a decade, the newspaper industry is the fastest to use violet lasers. At Drupa 2004, all suppliers (except one) considered violet lasers the only choice for newspaper CtP. Because of the violet laser, people can use the newspaper CtP at the lowest price, the fastest speed ever seen in the industry, the standard high quality and the high reliability of the laser.

So, press thermal CtP? From the standpoint of speed, cost, and laser reliability, thermal sensitivity cannot be compared with violet lasers, and this is clearly reflected in market share. But what about the possibility of flushing? Can thermal energy not be preferred because it is the only solution that provides flush-free CtP?
Prior to the advent of violet lasers, many believed that thermal was the only technology that could be used for no-rinsing. This is a foothold for some vendors to sell thermal CtP. But now this has completely changed. First of all, here is an assumption that all people will eventually need to wash. In fact, no-rinsing has its own characteristics and advantages, but these advantages are not suitable for newspaper CtP.

Why does CtP not use thermal-free flushing?

The following are two main factors that no-flushing does not apply to today’s newspaper industry:

1, speed

The sensitivity of the media is too low for the high-speed requirements of the newspaper CtP. Because all exposure-free or chemical-free plates are exposed at 300-400 mJ/cm2 or even higher. In contrast, the current newspaper leading CtP technology violet laser photopolymer version exposure is less than 100μJ/cm2. The violet laser photopolymer version is thousands of times more sensitive than the no-clean thermal version, so the platesetter can meet the speed requirements of the newspaper CtP. Therefore, the thermal CtP devices purchased today are unable to achieve the speed needed to produce a rinse-free version tomorrow, next year or later year. Any newspaper printer who purchased a thermal platemaking machine today and would like to use it to produce tomorrow's rinse-free version will be disappointed. Even though no-flushing is a technology suitable for newspapers, it is clear that it is several thousand times slower than violet laser plate making technology. Whether it is the current thermal-free rinse-free platesetter or other new models in design and development, it is not comparable to current violet laser platesetters in terms of speed and reliability.

2, printing performance

The flush-free version has a medium and high print-resistance, and it cannot meet the hundreds of thousands of prints required by newspaper professionals.

Another thing to keep in mind is that eliminating all the problems faced by newspapers today is not the most important issue. On the contrary, most newspapers hope to have a CtP that is guaranteed in terms of speed, consistency, quality, and most importantly reliability.

Newspaper CtP, Thermal or Violet Laser? - A Neutral Perspective

Is heat sensitivity the only way to avoid flushing? In the late 1990s, this was a point of view accepted by many suppliers, but with the advent of violet lasers, this argument has changed.

Today, and for the foreseeable future, violet lasers are the best combination of speed, reliability, and value for money. The only people who disagreed with this view were those who had desperately moved on thermal technology and had no choice.

Thermal is a good technology in some commercial printing markets, but it is certainly not at all suitable for the newspaper market. Some people claim that in spite of this, there is still a reason for purchasing thermal CtP, which is that it is the only way to future flushing. However, this hypothesis is not completely unrealistic because of the continuous development of violet lasers.

If the heat-sensitive technology is suitable for newspapers, then this industry and suppliers will embrace the thermal technology. Because heat is a mature technology, it can be purchased anytime from suppliers who actively sell purple laser press solutions today. However, the fact is that the purple laser is the most suitable technology for the newspaper industry. All suppliers, except one or two, will fully agree. Tip: Those who oppose the newspaper violet laser are those who do not have violet laser technology.

In this chaotic and often conflicting world, the most valuable CtP information from suppliers is the unbiased CtP advice. If you are a newspaper person who is interested in investing in CtP, please discuss with suppliers who have both thermal and violet laser technology to see if they give you advice.

Reprinted from: Print Magazine