A free-seal liquid flexoBag technology
An innovative option for flexo plate making in addition to solid and liquid plates
Hilson Huang / @flexoBag

In 1995, Montreal Protocol limited CFC production in force in order to regulate on ozone-depleting substances . The using of solvent washout chemicals of Perchloroethylene and 111-trichloethane is still a major issue on the subject, although there are so-called green chemicals or environmental friendly substitution which is in use, but unfortunately the problem of using solvent to washout a flexo plate is still there. Especially when recently the oil price keeps on increasing record high which means that using cost of washout solvent is also going up to 20-30% to a same size flexo plate cost which you are making.

To avoid this serious regulation, there are four ways to develop:

1. Environmental friendly green chemical.
2. Water washout flexo plates
3. Liquid photopolymer
4. Free-seal flexoBag technology

 
GREEN CHEMICALS:

Big giants in flexo industry such as DuPont, Flint …etc. had developed their own system of environmental friendly substitutions but it is however, they all still use solvent, most important is that its do not improved the washout result at all, if we observe it from the plate making results as well as from time consuming side.

Meantime, the derivational problem is the solvent recovery, due to substitution usage of strong solvent as a green chemical which means that boiling point will be increased
and increased because of the lower evaporating needs higher temperature meet the boiling point. The recovery machine may have to be re-modified or re-purchased for the higher temperature access and longer time for the process means more power consumption is needed thus the costs for a plate maker is increased again. Moreover, price is also a major issue, if could not reduce the plate making cost, green chemical is not friendly to the users.

WATER WASHOUT FLEXO PLATES:

The photopolymer resin for making flexo plates is various, which means that its not
easy to get a proper durometer plate as you want then you can have it or you want to have a plate for certain solvent ink resistance then you can have it. The materials to make a plate is versatile, are differ in multiple purposes such as physical characters (resilience, abrasion…etc) and printing adaptability (ink transfer, impressions… etc) these all will effect the plate been developed. For water washout flexo plate, it is more difficult to have an innovative break through. This is the reason why there is almost no new water washout plate appeared again in the market recently for a long time.

Since Uniroyal, Aqua-Flex have been developed in 1980s, thereafter seems, no new water washout flexo plates have been shown up in the market and then disappeared for a long time until now. Eventually Flex Light manufacturing plant has to be sold for many times.

However, in the other side of Pacific Ocean, Toyobo in Japan have developed their water wash flexo plate Cosmolight (in 1990s) in addition to their Printight (in 1970s) water washout plate for letterpress. Toray also put their Toreflex water wash flexo plates eventually after almost 20 years late.

Despite of so many manufacturers have developed their water wash flexo plates and put into the market, however, there are still several bottlenecks to break such as the washout machine have to be modified or repurchased for the water circulation and residue filtration are very important points for the water wash flexo plates so as to the higher washout temperature by which heat elements have to be strengthened, besides, although its named water wash plates actually still have to put certain percentage of detergent into the washout water in order to accelerate the washout speed. It is however, the drain of detergent water with photopolymer residues make more environment (drain) problems which means that without treatments the residue and water can not be released to the drain by plate makers.   

In addition, cost is an important issue, if price of water wash flexo plates are 50-60% higher cost than conventional solvent washout plates, this will keep away the steps of a plate maker or printer from using its, for if they are still using the solvent to washout a plate the solvent cost maybe only 20-30% as what they spend for the plate cost. This is also a very weak point to promote water wash flexo plates well until now. 

LIQUID PHOTOPOLYMER
Every body knows that in the past a liquid photopolymer plate making system is very expensive, a small unit may cost you USD 40000.- for big size plate making will cost you over USD 100000.-, The reason is the machine like a miniature manufacturing plant of photopolymer plates, to be equipped with coater, spreader, paving of base film and air escaping layer….etc. Especially have to pay more attention to the evenness of a plate and to avoid the bubbles remaining on the plate.

Liquid photopolymer is a high viscosity material with very sticky phase as glue before it is cured and hardened, therefore coating and spreading of it on the plate making machine is very slow, in addition, it is not easy to take off the bubbles which is occurred during the process. To make a plate requiring 1-2 hours is very common, which means that can make 4 plates in a working day up most.

These are disadvantages of conventional plate making from liquid photopolymer.  Now we are very proud to introduce this innovative new plate making technology – @flexoBag.

FLEXOBAG

This innovative new product is a new pattern of plate making in addition to solid plate and liquid plate making, this is a third option of plate making method. The merits are:

1. Sharp image

More clear image area than all of the photopolymer plates forever, for it is possible to use film directly as one side of the bag in order to have best contact results to form a very sharp image.
Solid plate all equipped with a “slip coat layer” to help escape of air between negative film and photo-sensitive resin during exposure which means that photopolymer is not contacting with negative film directly, so as to the conventional liquid plate making method.

1. Simple stock

For user, only preparation of stock is 18 kg liquid resin in pal, no matter what is the thickness, width and length plates they want to make, these can be all determined by the gauge and bag size in stead of preparing so many kinds of plate in stock.

1. Non bubbles

Bubbles are always an important issue for the liquid photopolymer plate maker,
by using a bag, bubbles can be reduced to a certain degree for immediate plate making, or can be pre-prepared before exposure to escape the bubbles in advance
before plate making.

1. Water washout

Washout of flexoBag is the same as conventional liquid photopolymer can washout by water. Water will save about 20 – 30 % of plate cost than it washout by solvent. Non toxic, non odor, non sticky, clean and easy handle are good advantages of water washout.

1. Cheaper equipment

Due to flexoBag and innovative design, the exposure can be as simple as only double glasses are needed but with double vacuum systems in between, and exposure machine can be very simple without any coating unit on it, therefore, the
capital investment cost can be reduced to only 30% of a conventional liquid resin plate making machine.

1. Costs reduction

This new liquid photopolymer is non bubble, wide latitude, good ink transfer, high resilience, abrasion resistance, fine resolution, tack-free, excellent shoulder support for long impressions as well as low production costs. It is only 30-50% cost of making a solvent washout plates.

1. Time saving

As explained, flexoBag is pre-filled under non bubble condition, therefore it is eliminating coating, spreading, waiting and taking off the bubbles, including exposure, washout, post exposure drying and treatment, total processing time can be done within 20 -30 minutes.(conventional liquid machine will take 90-120 minutes, because waiting for taking off the bubbles)

1. Quick ready for printing

No under water anti-tack exposure with chemical is required (no second drying is required), so after that plate can mount to a press for immediate printing. Total processing time is only 20 -30 % of a solvent washout plate. Due to no swelling so it does not have to wait over night until the plate is complete stabilized for good registration print. This is a major reason why people will like to use this new liquid photopolymer technology.