3. Manufacture of letterpress forms based on photopolymer compositions

A significant factor in the development of flexographic printing was the introduction of photopolymer printed forms. Their use began in the 1960s, when DuPont introduced the first Dycryl letterpress plates to the market. However, in flexo they could be used to make original cliches, from which matrices were made, and then rubber molds by pressing and vulcanization. A lot has changed since then.

Today, the following manufacturers of photopolymer plates and compositions are best known on the global flexographic printing market: BASF, DUPONT, Oy Pasanen & Co and others. pressure generated by the impression cylinder). These include paper, cardboard, corrugated cardboard, various synthetic films (polypropylene, polyethylene, cellophane, polyethylene terephthalate lavsan, etc.), metallized foil, combined materials (self-adhesive paper and film). The flexographic method is used mainly in the field of packaging production, and also finds application in the manufacture of publishing products. For example, in the USA and Italy, about 40% of total number of all newspapers are printed flexographically on special flexographic newspaper units.

There are two types of plate material for making flexographic plates: rubber and polymer. Initially, the plates were made on the basis of rubber material, and their quality was low, which, in turn, made the quality of flexo prints in general poor. In the 70s of our century, a photopolymerizable (photopolymer) plate was first introduced as a plate material for the flexographic printing method. The plate made it possible to reproduce high-line images up to 60 lip/cm and above, as well as lines with a thickness of 0.1 mm; dots with a diameter of 0.25 mm; text, both positive and negative, from 5 pixels and bitmap 3-, 5-, and 95-percentage points; thus allowing flexography to compete with the "classic" methods, especially in the field of packaging printing. And, naturally, photopolymer plates have taken a leading position as a plate flexographic material, especially in Europe and in our country.

Rubber (elastomer) printing plates can be obtained by pressing and engraving. It should be noted that the molding process itself based on elastomers is laborious and not economical. The maximum reproducible lineature is about 34 lines/cm, i.e. the reproduction capabilities of these plates are at a low level and do not meet modern packaging requirements. Photopolymer forms make it possible to reproduce both complex color and transitions, various tonalities, and raster images with a lineature of up to 60 lines / cm with a rather small spreading (increase in tonal gradations). Currently, as a rule, photopolymer forms are made in two ways: analog - by exposing UV radiation through a negative and removing unpolymerized polymer from gaps using special wash solutions based on organic alcohols and hydrocarbons (for example, using a wash solution from BASF Nylosolv II ) and by means of the so-called digital method, i.e., laser exposure of a special black layer applied over a photopolymer layer, and subsequent washing out of unexposed areas. It is worth noting that in recent times in this area, new developments by BASF have appeared, making it possible to remove the polymer in the case of analog plates using ordinary water; or directly remove the resin from the gaps using laser engraving in the case of digital mold making.

The basis of a photopolymer plate of any type (both analog and digital) is a photopolymer, or the so-called relief layer, due to which the formation of raised printing and recessed blank elements, i.e. relief, occurs. The basis of the photopolymer layer is a photopolymerizable composition (FPC). The main components of FPC, which have a significant impact on the printing and technical characteristics and quality of photopolymer printing plates, are the following substances.

1) Monomer - a compound of relatively low molecular weight and low viscosity, containing double bonds and, therefore, capable of polymerization. The monomer is a solvent or diluent for the remaining components of the composition. By changing the monomer content, the viscosity of the system is usually controlled.

2) Oligomer - capable of polymerization and copolymerization with a monomer, an unsaturated compound of a molecular weight greater than the monomer. These are viscous liquids or solids. The condition for their compatibility with the monomer is solubility in the latter. It is believed that the properties of cured coatings (eg photopolymer printing plates) are determined mainly by the nature of the oligomer.

As oligomers and monomers, oligoether- and oligourethane acrylates, as well as various unsaturated polyesters, are most widely used.

3) Photoinitiator. The polymerization of vinyl monomers under the action of UV radiation can, in principle, proceed without the participation of any other compounds. This process is simply called polymerization and is rather slow. To speed up the reaction, small amounts of substances (from fractions of a percent to percent) are introduced into the composition, capable of generating free radicals and/or ions under the action of light, initiating a polymerization chain reaction. This type of polymerization is called photoinitiated polymerization. Despite the insignificant content of the photoinitiator in the composition, it belongs exclusively to important role, which determines both many characteristics of the curing process (photopolymerization rate, exposure latitude) and the properties of the resulting coatings. Derivatives of benzophenone, anthraquinone, thioxanthone, ascilphosphine oxides, peroxy derivatives, etc. are used as photoinitiators.

The nyloflex ACE plate is designed for high quality flexo screen printing in areas such as:

Flexible film and paper packaging;

Beverage packaging;

Labels;

Pre-sealing of corrugated cardboard surface.

It has the highest hardness among all nyloflex plates - 62 ° Shore A (Shore A scales). Main advantages:

Plate color change during exposure - the difference between exposed / unexposed areas of the plate is immediately visible;

Large exposure latitude ensures good fixation of halftone dots and clean indentations on reverses, masking is not required;

Short processing time (exposure, washout, post-processing) saves working time;

A wide range of tone gradations on the printed form allows you to simultaneously print raster and line elements;

Good contrast of printed elements facilitates installation;

High-quality ink transfer (especially when using water-based inks) allows you to evenly reproduce the raster and solid, and reducing the required amount of transferred ink makes it possible to print smooth raster transitions;

High hardness with good stability, transfer of high-line raster transitions when using the technology of "thin printing plates" in combination with compression substrates;

Wear resistance, high circulation-resistance;

Ozone resistance prevents cracking.

The plate shows excellent ink transfer, especially when using water-based inks. In addition, it is well suited for printing on rough materials.

Nyloflex ACE can be supplied in the following thicknesses:

ACE 114-1.14mm ACE 254-2.54mm

ACE 170-1.70 mm ACE 284-2.84 mm

The plate has a low hardness (33° Shore A), which ensures good contact with the rough and uneven surface of the corrugated board and minimizes the washboard effect. One of the main advantages of FAC-X is its excellent ink transfer, especially for water-based inks used in printing on corrugated board. Uniform printing of plates without high printing pressure helps to reduce the increase in gradations (dot gain) during raster printing and increase the contrast of the image as a whole. In addition, the plate has a number of other distinctive features:

The violet shade of the polymer and the high transparency of the substrate make it easier to control images and mount forms, using adhesive tapes, on a plate cylinder; - high bending strength of the plate eliminates peeling of the polyester substrate and protective film;

The form is well cleaned both before and after printing.

The nyloflex FAC-X plate is single layer. It consists of a photosensitive photopolymer layer deposited on a polyester substrate for dimensional stability.

Nyloflex FAC-X is available in 2.84mm, 3.18mm, 3.94mm, 4.32mm, 4.70mm, 5.00mm, 5.50mm, 6.00mm, 6.35mm .

The relief depth of the nyloflex FAC-X plates is set by pre-exposing the reverse side of the plate by 1 mm for plates with a thickness of 2.84 mm and 3.18 mm and in the range from 2 to 3.5 mm (depending on each specific case) for plates with a thickness of from 3.94mm to 6.35mm.

With nyloflex FAC-X plates, it is possible to obtain screen lineature up to 48 lines / cm and a gradation interval of 2-95% (for plates with a thickness of 2.84 mm and 3.18 mm) and a screen lineature of up to 40 lines / cm and a gradation interval of 3-90% (for inserts with a thickness of 3.94 mm to 6.35 mm). The choice of plate thickness is guided both by the type of printing machine and the specifics of the printed material and the reproduced image.

The digiflex II photopolymer plate was developed from the first generation of digiflex plates and combines all the advantages of digital communication with even simpler and easier processing. Benefits of the digiflex II plate:

1) No photographic film, which enables direct transfer of data to the printing plate, protecting the environment and saving time. After removing the protective film, a black layer becomes visible on the surface of the plate, which is sensitive to infrared laser radiation. Image and text information can be written directly on this layer using a laser. In places that are affected by the laser beam, the black layer is destroyed. After that, the printing plate is exposed to UV rays over the entire area, washed, dried, and the final illumination occurs.

2) optimal transfer of gradations, allowing to recreate the slightest shades of the image and providing high quality printing;

3) low installation costs;

4) the highest quality of the press. The basis of laser-exposed photopolymer printing plates are nyloflex FAH printing plates for highly artistic raster flexographic printing, which are covered with a black layer. The laser and subsequent conventional exposures are chosen such that significantly lower gradation increments are achieved. Get print results exclusively High Quality.

5) reduced load on environment. No film processing not used chemical compositions for photo processing, closed exposure and washing units with closed regeneration devices lead to a reduction in the harmful impact on nature.

The scope of plates for digital transmission of information is wide. These are paper and film bags, corrugated cardboard, films for automatic machines, flexible packaging, aluminum foil, film bags, labels, envelopes, napkins, beverage packaging, cardboard products.

Nyloflex Sprint - new for Russian market plate from the nyloflex series. At the moment, it is being tested at a number of production printing enterprises in Russia. This is a special water washable plate for printing with UV inks. Washing with ordinary water makes sense not only from a nature protection point of view, it also significantly reduces the processing time compared to the technology using an organic wash solution. The nyloflex sprint plate requires only 35-40 minutes for the entire deprinting process. Due to the fact that for washing out you need only pure water, nyloflex sprint also saves on additional operations, because the used water can be poured directly into the sewer without filtration or additional treatment. And for those who already work with nyloprint water-washable plates and letterpress processors, they don't even need to buy additional equipment.

Usage: in printing for the manufacture and processing of letterpress photopolymer clichés, The essence of the invention: the finished photopolymer printing plate is irradiated with an electron beam and / or y-quanta in the energy range of 0.5-10 MeV with a particle flux density of 10tT-1012 particles / cm2 s in within 1-30 min. 1 tab.

RESG!U1 LIK (19) s

K (2 (2 (4 (7 ve (7 (7 ve (5

F m skrash f m to st g

STRONG 1-!OE IlAI F. I I I IOE house of the ussr

SPATENT USSR)) 5018354/12

) 08/30/93. Bull. No. 32

) A.P. Ignatiev, V.A. Senyukov and M.E. Berg

) Limited Liability Partnership "Firma Triam"

6234. class B 41 N 1/00, 1983.

The invention relates to a technology for the production and processing of photopolymer ate forms based on a solid photoporous material, in particular letterpress topolymer clichés, and can be used in the printing industry.

The purpose of the invention is to expand the temperature range of use and improve the performance characteristics of the topolymer printing plate by changing the physico-mechanical properties of the foiler. /or y-quanta in the energy shaft 0.5 - 10 MeV with a particle flux density of 10 -10 particles / (cm, s) value 1 - 30 min.

The essence of the proposed honeycomb method is that the finished polymer form is exposed to ionizing (sI>c B 41 N 1/00, B 41 C 1/10, G 03 F 7/26 (54) : in printing for the manufacture and processing of letterpress photopolymer cliches, The essence of the invention: the finished photopolymer printing plate is irradiated with an electron beam and / or y-quanta in the energy range of 0.5 - 10 MzV with a particle flux density of 10 -10 particles / cm s in tt 12 2 for 1 - 30 min. 1 radiation table, while the products of ionization and excitation of the molecules of polymer compounds are distributed over the volume of the irradiated printing plates in accordance with the distribution of absorbed doses. Thus, selecting the appropriate distribution and dose rate in the irradiated sample , it is possible to obtain new desirable properties of the photopolymer compound that do not arise without a radiation chemistry™ process. -quanta allows you to expand the temperature range of using photopolymer plates up to 200 C, increase the elastic limit and Young's modulus, increase the hygroscopicity of photopolymer printing plates, which ultimately improves. performance characteristics of letterpress photopolymer clichés and allows them to be used at elevated temperatures.

1838158 known photopolymers of the type "Cellophot" and "Flexophot" as follows.

Example 1. A sample of a printing plate made of a photopolymer of the Cellophot type is irradiated with an electron beam with an energy of 8 MeV for 15 minutes with an electron beam current equal to

19 μA, Measurement of physical and mechanical parameters is carried out at a temperature of 20 C, Example 2. A sample of a printing plate of a photopolymer of the "Flexophot" type is irradiated with an electron beam with an energy of 10 MeV with an electron beam current of 10 μA for 25 minutes. Measurement of physical and mechanical parameters is carried out at a temperature of 20 C, 15

Example 3. Similar to example 1.

Measurement of physical and mechanical parameters is carried out at a temperature of 140 C.

The modes of the method were chosen based on the following considerations: at an electron energy below 0.5 MeV (Ee 10 MeV, photonuclear reactions, the equipment is activated, a radiation hazard arises, When the electron flux density

P 10 electrons/cm.s, a significant amount of absorbed energy leads to radiation heating and destruction of the photopolymer plate.

In the study of changes in the physico-mechanical properties of photopolymers on- "O", the following characteristics were determined, the modulus of elasticity (Young's modulus), the limit of elasticity, and hygroscopicity.

Research data on the physical and mechanical properties of photopolymers are given in Table 45.

From the Bèäno table, after irradiation, for a photopolymer of the "Cellophot" type, in comparison with the initial sample, the elastic modulus increases by 30-40, and the elastic limit - by 4 times. For photopolymer type

"Fleksofot" after irradiation compared with the original sample, Young's modulus increases by 4.8 times, the elastic limit by 44 times, and the hygroscopicity by 50, which significantly affects the quality of the prints. Photopolymer type "Fleksofot" after irradiation becomes hydrophilic, which makes it possible to use various stamp inks to obtain prints up to ordinary inks without reducing the quality of prints.

"Cellophot" at elevated temperature (up to 150 C) showed that Young's modulus increases by 1.8 times, the elastic limit - by 3.6 times, and if at elevated temperature the run time of non-irradiated cellophote is 0, then after irradiation the number of prints is 10,000 copies. Increasing the thermal stability of the "Cellophot" type photopolymer under the action of ionizing radiation will make it possible to abandon the use of metal in the creation of printing plates operating at elevated temperatures. method, operable at a temperature of the order

200 C and can be used more than 10,000 times without destroying the printing plate.

1.Create a print layout:

Draw a print layout with the necessary data on a computer in any program and invert it into a negative (black and white) image.
We offer the program CoralDraw to create a print layout and to help "beginners" a disk - "Seals and stamps. Protective elements" (3000 rubles), with a large selection of layouts, fonts, templates and images.

2.Print layout:

Print on a laser printer with a resolution of at least 600 dpi on matte Kimoto film or transparent LOMOND (pay attention to the quality of the negative).

3. Toner the negative:

Process the negative with toner, after which the dark background should darken. Use original cartridges and toner.

4. Place the negative on the glass:

After wetting the reverse side of the film, place the negative face up on the glass, previously moistened with water (for better adhesion).

5. Cover the negative with a protective film (optional):

Cover the negative with a protective film on top (optional). With smoothing movements, drive out the remaining water from under the film (to prevent the formation of air bubbles and better contact).

6. Paste with curb tape:

Glue around the perimeter with a border tape that limits the space for the polymer, while leaving gaps in the corners.

7.Fill the negative with photopolymer:

Evenly, without interrupting the jet, fill the negative with photopolymer and remove the formed bubbles by blowing air from a rubber bulb or a sharp object (paper clip, toothpick, needle).

8. Cover with a substrate film:

Cover with a film-substrate (On the polymer with a rough side! Glossy outside!), Starting from the middle, as shown in the figure. We touch the center of the polymer with a film without pressing and simply release the edges - they will straighten themselves out and fall on the polymer.

9. Cover with a second glass:

Cover the resulting composition with a second glass and clamp along the edges with clips (stationery clips are bought separately at any stationery store).

10. Place in the exposure chamber:

Place the glass cassette face up in the exposure chamber.

11.Start the timer:

Set the exposure time on the digital timer, which largely depends on the properties of the photopolymer. For polymer grades VX55, ROEHM on the side of the transparent film (first time) it is approximately 20 -30 sec. Start the timer by pressing the CD button. At the same time, the timer will start counting down the time, and a blue glow from the lamps will appear inside.

12. Set the exposure time on the timer:

After the timer counts down and the lamps go out, turn the cassette over with the matte film (negative) up and start the exposure process again (CHANGING THE TIME). For polymer grades VX55, ROEHM exposure time for reverse side(second time) is 1 min. A more accurate time is determined empirically by changing the time of both exposures. See the brochure "Technological regulations". When finished, remove the cassette from the camera.

13. Having separated the glass, separate the negative:

After carefully separating the glasses, separate only the negative and the protective thin film from the photopolymer. Do not separate the substrate (transparent) from the print. After removing the hardened polymer from the glasses, some of it remains liquid, so it must then be washed.
ATTENTION!
Very often, novice manufacturers violate the manufacturing technology, namely, the print must necessarily contain a rigid basis for printing - the substrate! This film has two sides, one of which the rough side is superimposed on the photopolymer, and the smooth side is later used for gluing onto adhesive tape (on the tooling, on the body). It does not need to be separated from the photopolymer after the manufacturing process!
For example: if you make a comparison - imagine a person who does not have a bone skeleton, and a print without a substrate.

14. Rinse Cliche:

To remove uncured resin, wash the cliché well with a brush and detergent and degreaser such as Fairy, Cinderella under warm (not hot) running water.

15. Place the cliché into the water:

Place the cliche in a bath of water in the exposure chamber for 7-10 minutes to harden.

16. Cut off excess polymer:

Cut out the cliche, cut off all excess polymer. Cut carefully without touching the sides, otherwise the print will be rejected. This step must be taken very carefully so that you do not have to repeat everything from the beginning.

17. Cliche to stick on the snap:

Glue the finished cliché onto the snap.

In our store, visit the section where you can purchase consumables.

Flexography is a type of letterpress printing, characterized by the use of elastic printing plates and low-viscosity, quick-drying inks.

Elastic printing plates have significant advantages over rigid forms: the ability to print at low pressure printing on various, including non-absorbent materials (paper, cardboard, films, plastics, cellaphan, metal, etc.). At the same time, they are distinguished by high circulation stability, over 1 million copies.

At the present moment, three main areas of application of flexographic forms have been identified:

• Forms for sealing flexible packaging;
• Forms for sealing cardboard, corrugated cardboard and materials with a rough surface;
• Forms for varnishing offset prints.

Thin forms are used for high-quality raster flexographic printing, thicker ones with deep relief are used for sealing corrugated cardboard.

Forms are designed for printing with flexographic inks on an alcohol or water basis, UV inks and varnishes. They are compatible with oil paints and aggressive solvents such as acetates or ketones.

The method of manufacturing photopolymer flexographic forms is based on the same principle as the method of obtaining conventional photopolymer letterpress forms, i.e., the formation of printing elements by polymerization of the material under the action of radiation, and the removal of unhardened mass in the areas where gaps form.

There are two directions for the production of photopolymer flexographic forms: from solid materials and from liquid ones.

Production of photopolymer flexographic forms from solid materials. As a solid material, a plate produced under industrial conditions is used, which consists of several layers (Fig. 11): a protective film, a separating layer, a polymer layer and a polyester film.

Rice. eleven.

The polyester backing and protective film (i.e. outer layers) protect the polymer layer from direct contact with the environment.

At the same time, the plate remains flexible and elastic. The format and thickness of the required plate is determined by the design printing machine.

For conventional photopolymer forms, the negative is used as the original.

The process of obtaining photopolymer flexographic forms is carried out using specialized equipment. For exposure, mercury lamps of UV radiation with a wavelength of 360 mm are used. The exposure itself is carried out in an exposure device with a vacuum system for pressing the negative and the form against each other. Washing and drying devices are used to remove non-hardened masses and dry them.

The process of manufacturing a flexographic plate from solid photopolymerizable materials consists of the following steps:

• 1. Exposure reverse side.
• 2. Main exposure (image exposure).
• 3. Washout.
• 4. Drying.
• 5. Additional processing by light.
• 6. Additional exposure.

Reverse exposure is the effect of UV radiation on the polymer layer through the polyester film - the base. This operation has several purposes:

• - the depth of the relief for the finished printing form is determined;
• - due to the increase in light sensitivity, the exposure time of the image is reduced, in particular, free-standing and small image elements;
• - the stability of the printing elements is increased due to a strong connection with the base of the relief and a stable structure of the side faces is ensured;
• - provides adhesion between the polyester base and the polymer layer;
• - in the process of washing out, the absorption of the solvent and the maximum depth of washing out are limited.

Before the main exposure, the protective film is removed from the mold surface. The negative is applied to the plate with the emulsion side. During this technological operation, a positive relief image is formed on the form. Image building starts at the surface of the plate and moves down in the form of a cone, thereby providing an ideal, for letterpress forms, the profile of printing elements with sharp borders and side faces.

Solvent rinsing and brushing removes non-polymerized portions of the mold. What remains is a relief with a surface corresponding to the transparent areas of the negative.

The drying process evaporates the solvent absorbed into the mold during washing. The form acquires the desired thickness, but the surface remains quite sticky. The drying operation is carried out using dryers.

After post-treatment with 254mm UV and final exposure with 360mm UV, the mold is given its final strength and durability by cross-linking all monomer parts. Additional processing is carried out in special finishing installations.

Production of photopolymer flexographic forms from liquid materials. The method of obtaining photopolymer flexographic forms from liquid materials has no fundamental differences from the method of obtaining the same forms from solid plates, except for the state of aggregation of the material itself. characteristic feature This technology is the use of equipment specialized for this method, each type of which combines the performance of several technological operations:

• 1. Coating and exposure device
• 2. Device for removing non-polymerized material, washing out, additional exposure, additional processing, drying.
• 3. Reservoir for liquid polymer.

Each of these settings has options depending on the format of the form. The whole process is carried out in a semi-automatic mode.

Production of photopolymer flexographic forms using laser and digital technology. This technology involves the use of plates containing a solid photopolymerizable material. A characteristic feature of plate plates specially made for this method is the presence of a laser-sensitive layer (Fig. 12).

Rice. 12.

All processes of this technology do not differ from the technology of manufacturing photopolymer flexographic plates from solid materials, with the exception of the main exposure stage. Receiving form does not involve the use of negativity. The image from the publishing system computer is transferred to the laser exposure device. After removing the upper protective film, areas corresponding to future printed elements are burned on the laser-sensitive layer - a so-called mask is created. Next, the photopolymerizing layer is exposed to UV rays through a mask. The mask has a sufficiently tight contact with the photopolymerizing layer, and it is not required to use a vacuum for additional pressure. The latter circumstance leads to less scattering of UV rays and the formation of sharper printing elements, which slightly improves image quality.

Modern photopolymer forms (FPF). General scheme for the manufacture of the FPF

The use of photopolymer printing plates began in the 60s. An essential factor in the development of flexographic printing was the introduction of photopolymer printing plates. Their use began in the 1960s, when DuPont introduced the first Dycryl letterpress plates to the market. However, in flexo they could be used to make original cliches, from which matrices were made, and then rubber molds by pressing and vulcanization. A lot has changed since then.

Today, the following manufacturers of photopolymer plates and compositions are best known on the global flexographic printing market: BASF, DUPONT, Oy Pasanen & Co and others. pressure generated by the impression cylinder). These include paper, cardboard, corrugated cardboard, various synthetic films (polypropylene, polyethylene, cellophane, polyethylene terephthalate lavsan, etc.), metallized foil, combined materials (self-adhesive paper and film). The flexographic method is used mainly in the field of packaging production, and also finds application in the manufacture of publishing products. For example, in the USA and Italy, about 40% of the total number of all newspapers are printed flexographically on special flexographic newspaper units. There are two types of plate material for making flexographic plates: rubber and polymer. Initially, the plates were made on the basis of rubber material, and their quality was low, which, in turn, made the quality of flexo prints in general poor. In the 70s of our century, a photopolymerizable (photopolymer) plate was first introduced as a plate material for the flexographic printing method. And, naturally, photopolymer plates have taken a leading position as a plate flexographic material, especially in Europe and in our country.

Production of the FPF.

In the manufacture of photopolymer forms of flexographic printing, the following main operations are performed:

• 1) preliminary exposure of the reverse side of the photopolymerizable flexographic plate (analogue) in the exposure unit;
• 2) the main exposure of mounting the photoform (negative) and the photopolymerizable plate in the exposure unit;
• 3) processing of a photopolymer (flexographic) copy in a solvent (washout) or thermal (dry heat treatment) processor;
• 4) drying of the photopolymer form (solvent-washable) in a drying device;
• 5) additional exposure of the photopolymer form in the exposure unit;
• 6) additional processing (finishing) of the photopolymer form to eliminate the stickiness of its surface.