JP6559284B2 - Equipment for thermal processing of flexographic printing elements - Google Patents

Description

  The present invention relates generally to an apparatus for thermal processing of flexographic printing elements and methods of use thereof.

  Flexographic printing is a printing method generally used for mass production. Flexographic printing is employed for printing on various substrates such as paper, paperboard materials, cardboard, film, foil, and laminates. Newspapers and shopping bags are the main examples. Rough surfaces and stretchable films can only be printed economically by flexographic printing. A flexographic printing plate is a relief plate with image elements raised above the open area. Such plates provide many advantages to the printer, primarily due to their durability and ease of manufacture.

  A standard flexographic blank supplied by the manufacturer is in turn composed of a backing layer, ie a support layer, one or more unexposed (uncured) photopolymer layers, a protective layer or slip film, and a cover sheet. It is a multilayer article.

  The one or more unexposed photopolymer layers can include any of the known photopolymers, monomers, initiators, reactive or non-reactive diluents, fillers, and dyes. The term “photocurable” refers to a solid composition that undergoes polymerization, crosslinking, or any other curing or solidification reaction in response to actinic radiation, resulting in exposure of an unexposed portion of the material ( It can be selectively separated and removed from the (cured) portion to form a three-dimensional relief pattern of the cured material. Preferred photocurable materials include elastomeric compounds, ethylenically unsaturated compounds having at least one terminal ethylene group, and photoinitiators. Exemplary photo-curable materials are disclosed in US Pat. Nos. 5,098,059 and 5,098,097, incorporated herein by reference in their entirety. If a second photocurable layer, i.e. a coating layer, is used, it is typically disposed on the first layer and has a similar composition.

  Photopolymer materials generally crosslink (cur) and solidify at least in some actinic wavelength range. As used herein, actinic radiation is radiation that can cause a chemical change in an exposed area. Examples of actinic radiation include amplified (eg, laser) light and non-amplified light, particularly in the UV and infrared wavelength regions. A preferred actinic wavelength range is from about 250 nm to about 450 nm, more preferably from about 300 nm to about 400 nm. One suitable source of actinic radiation is a UV lamp, although other sources of actinic radiation are generally known to those skilled in the art.

  Photopolymer printing elements are commonly used in “flat” sheet shapes, but have special applications and advantages using continuous cylindrical printing elements as “continuous in-the-round” (CITR) photopolymer sleeves There is also. CITR sleeves are used for printing continuous designs such as wallpaper, decorative paper, and gift wrap. Standard CITR photopolymer sleeves generally include a sleeve carrier (support layer) and at least one unexposed photocurable layer on the support layer.

  A flexographic printing element is made from a photopolymer printing blank by forming an image on the photopolymer printing blank to form a relief image on the surface of the printing element. This is generally accomplished by selectively exposing the photocurable material to actinic radiation, and the effect of the exposure causes the photocurable material in the irradiated area to solidify, ie, crosslink. Regions that are not exposed to actinic radiation can be removed in subsequent steps.

  The printing element is selectively exposed to actinic radiation by one of several related methods. In the first method, a negative having a transmissive region and a substantially opaque region is used to selectively block the transmission of actinic radiation to the printing plate element. In the second method, the photopolymer layer is coated with a layer that is easy to ablate with a laser and does not (substantially) transmit actinic radiation. A laser is then used to ablate selected areas of the layer that do not transmit actinic radiation to form an in situ negative. This technique is well known in the art, and is described, for example, in US Pat. In the third method, the photopolymer is selectively exposed using a focused beam of actinic radiation. Any of these methods are applicable, the criteria being that a portion of the photopolymer can be selectively cured by selectively exposing the photopolymer to actinic radiation.

  Any conventional source of actinic radiation can be used for this exposure step. Suitable visible light sources and ultraviolet light sources include, but are not limited to, for example, carbon arcs, mercury vapor arcs, fluorescent lamps, electronic flash devices, electron beam devices, and photographic flood lamps.

  After imaging, the photosensitive printing element is processed, or “developed”, without disturbing the cured portion of the photopolymer layer to remove the uncured (ie, uncrosslinked) portion of the photopolymer layer, and the surface of the printing element. A relief image is formed on top. Common development methods include washing with various solvents or water, and brushes are often used. Other development options include thermal development or the use of an air knife.

  In the flexo prepress printing industry, it is highly desirable to eliminate the need for chemical processing of printing elements in relief image development in order to move from plate to printing more quickly. Therefore, a process has been developed in which a photopolymer printing plate is produced using heat, and a latent image is developed by utilizing a difference in melting temperature between a cured photopolymer and an uncured photopolymer. The basic parameters of this process are known and are described in US Pat. With these processes, the development solvent and the drying of the plate over the long time required to remove the solvent can be omitted. The speed and efficiency of this process allows it to be used in the manufacture of flexographic printing plates for printing newspapers and other publications where rapid delivery and high productivity are important.

  The photopolymer is a composition such that when exposed to heat, there is a substantial difference in properties between the cured polymer and the uncured polymer. It is precisely this difference that allows image formation in photopolymers cured on heating. At the temperature selected for thermal processing, the uncured photopolymer (ie, the portion of the photopolymer layer not in contact with actinic radiation) melts or is substantially softened while the cured photopolymer remains solid. It does not change. Therefore, an image can be formed by selectively removing the uncured photopolymer due to the difference in properties.

The printing element is heated to a temperature sufficient to cause melting or softening by conduction, convection, or other heating methods known in the art. For example, the printing element can be heated to a temperature of at least about 70 ° C, more typically from about 120 ° C to about 200 ° C. The exact temperature will vary depending on the characteristics of the particular photopolymer used. However, in general, when determining the development temperature, the following two main factors are considered.
1) The development temperature is preferably set between the melting temperature or softening temperature of the uncured photopolymer as the low temperature end and the melting temperature or softening temperature of the cured photopolymer as the high temperature end. As a result, the photopolymer can be selectively removed to create an image.
2) The higher the development temperature, the faster the processing time. However, the development temperature should not be so high as to degrade the cured photopolymer. The temperature must be sufficient to melt or substantially soften the uncured photopolymer, which allows the uncured photopolymer to be removed.

  When the printing element is heated, the uncured photopolymer can be melted or removed. The heated printing element is contacted with a material that absorbs or otherwise removes the softened or melted uncured photopolymer. This removal process is commonly referred to as “blotting” and is generally accomplished using an absorbent web of material. As long as the material can withstand the operating temperature involved, either woven or non-woven material can be used and the material can be polymer or paper. Wiping is accomplished by conveying the wiping material using one or more rollers and contacting it with a heated printing plate element.

  The uncured photopolymer layer is heated to a temperature sufficient to cause melting by conduction, convection, or other heating methods. By maintaining intimate contact between the absorbent sheet material and the photocurable layer to some extent, the uncured photopolymer is transferred from the photopolymer layer to the absorbent sheet material. While in the heated state, the absorbent sheet material is separated from the cured photopolymer layer in contact with the support layer, exposing the relief structure. After cooling, the resulting flexographic printing plate can be attached to a printing plate cylinder.

  Upon completion of the development process, the printing plate element is optionally but preferably subjected to further actinic radiation post-exposure and / or tack reduction. The printing element is ready for use after cooling.

General thermal development (also known as thermal processing) equipment is
a) means for supporting the flexographic printing element;
b) a heating means for softening or melting the non-crosslinked photopolymer on the imaged exposed surface of the flexographic printing element;
c) at least one roll capable of contacting the wipe with the surface of the flexographic element and removing softened or melted non-crosslinked photopolymer on the surface of the flexographic element;
d) means for maintaining contact between the at least one roll and the surface of the flexographic printing element;
including.

  U.S. Patent Nos. 6,028,036 and 5,037,046, incorporated herein by reference in their entirety, are sufficient to selectively melt or soften uncured portions of at least one layer of photopolymer. In which the printing element is heated and the heated printing element is brought into contact with a wiping material so that the softened or melted uncured photopolymer can be removed from the printing element.

  One problem that can occur with thermal processing is that the wiping material may not carry away any uncured photopolymer. Various methods have been used previously to prevent the accumulation of uncured photopolymer material on the surface of hot rolls. For example, the hot roll may be covered with a non-stick coating to prevent adhesion of uncured photopolymer to the hot roll, and the hot roll is rotated in a reverse cycle periodically with respect to the stationary blotter. Or the hot roll may be manually cleaned by mechanical cleaning (ie, abrasive), the use of a chemical cleaning solution, or both. However, the use of periodic reverse cycle rotation and manual cleaning of hot rolls both require the thermal processing apparatus to be taken offline for cleaning. Furthermore, if the hot roll is covered with a non-stick coating, the non-stick coating will eventually wear out, especially at high temperatures in thermal processing equipment, and the operation will be interrupted.

  Accordingly, there remains a need in the art for an improved heat development processing apparatus that includes improved means for cleaning hot rolls and overcomes the disadvantages of the prior art.

European Patent Application No. 0456336A2 (Goss et al.) European Patent Application Publication No. 0640878A1 (Goss et al.) British Patent No. 1,366,769 (Berrier et al.) US Pat. No. 5,223,375 (Berrier et al.) US Pat. No. 3,867,153 (MacLahan) US Pat. No. 4,264,705 (Allen) US Pat. No. 4,323,636 (Chen et al.) US Pat. No. 4,323,637 (Chen et al.) US Pat. No. 4,369,246 (Chen et al.) US Pat. No. 4,423,135 (Chen et al.) US Pat. No. 3,265,765 (Holden et al.) US Pat. No. 4,320,188 (Heinz et al.) US Pat. No. 4,427,759 (Grutzmacher et al.) US Pat. No. 4,622,088 (Min) US Pat. No. 5,135,827 (Bohm et al.) US Pat. No. 5,262,275 (Fan) US Pat. No. 6,238,837 (Fan) US Pat. No. 5,925,500 (Yang et al.) US Pat. No. 7,122,295 US Pat. No. 6,773,859 US Pat. No. 5,279,697 US Pat. No. 5,175,072 U.S. Pat. No. 3,264,103 US Patent Application Publication No. 2006/0122409 (Markhart et al.) US Patent Application Publication No. 2010/0119978 (Vest et al.) International Publication No. 01/88615 International Publication No. 01/18604 European Patent No. 1,239,329

  An object of the present invention is to provide an improved thermal development apparatus.

  Another object of the present invention is to provide an improved thermal development apparatus having an improved cleaning mechanism for preventing the accumulation of uncured photopolymer material on the surface of a hot roll.

  Yet another object of the present invention is to provide an improved thermal development apparatus that does not require the use of a wipe.

To this end, in one embodiment, the present invention generally relates to an apparatus for thermally processing a relief image printing element, the relief image printing element comprising at least one photopolymer layer, The relief image printing element is selectively exposed to actinic radiation to cross-link a portion of the at least one photopolymer layer while simultaneously exposing a portion of the at least one photopolymer layer to actinic radiation. Not cross-linked,
a) means for supporting the relief image printing element;
b) a heating means for melting or softening a non-crosslinked portion of the at least one photopolymer layer;
c) at least one rotatable roll capable of bringing a wiping material into contact with the at least one photopolymer layer and removing a melted or softened non-crosslinked portion of the at least one photopolymer layer. A nip is formed between the means for supporting the relief image printing element and the at least one rotatable roll, wherein the at least one rotatable roll is relative to the relief image printing element. A roll that, upon rotation, transfers the melted or softened non-crosslinked portion of the at least one photopolymer layer from the relief image printing element to the wipe;
d) an element disposed adjacent to the at least one rotatable roll to remove uncrosslinked photopolymer left on the surface of the at least one rotatable roll after step c);
The present invention relates to an apparatus including:

In another embodiment, the present invention is generally an apparatus for thermally processing a relief image printing element, the relief image printing element comprising at least one photopolymer layer, wherein the relief image printing element Is selectively exposed to actinic radiation to cross-link a portion of the at least one photopolymer layer, while at least a portion of the at least one photopolymer layer is cross-linked without being exposed to actinic radiation. Without
a) means for supporting the relief image printing element;
b) a heating means for melting or softening a non-crosslinked portion of the at least one photopolymer layer;
c) at least one rotatable roll disposed adjacent to the means for supporting the relief image printing element and removing a melted or softened uncrosslinked portion of the at least one photopolymer layer, A nip is formed between the means for supporting the relief image printing element and the at least one rotatable roll, and the at least one rotatable roll rotates relative to the relief image printing element. A roll in which a melted or softened non-crosslinked portion of the at least one photopolymer layer is transferred from the relief image printing element to the surface of the at least one rotatable roll;
d) adjacent to the at least one rotatable roll for scraping off the melted or softened non-crosslinked portion of the transferred at least one photopolymer layer from the surface of the at least one rotatable roll; Scraping means disposed at a rear position of the nip;
e) a waste container arranged to contain the non-crosslinked photopolymer scraped from the surface of the at least one rotatable roll;
Relates to an apparatus including

For a more complete understanding of the present invention, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
FIG. 1 illustrates an apparatus for thermally processing a relief image printing element of one embodiment of the present invention. FIG. 2 shows additional functions of the apparatus described in FIG. FIG. 3 shows an apparatus for thermally processing a relief image printing element of another embodiment of the present invention. FIG. 4 illustrates additional functions of the apparatus described in FIG. Moreover, although not all elements may be labeled in each drawing, elements with the same number indicate similar or identical parts.

In one embodiment, the present invention is generally an apparatus for thermally processing a relief image printing element, wherein the relief image printing element comprises at least one photopolymer layer, the relief image printing element comprising: A portion of the at least one photopolymer layer is selectively exposed to actinic radiation, and at the same time, a portion of the at least one photopolymer layer is not crosslinked without being exposed to actinic radiation. ,
a) means for supporting the relief image printing element;
b) a heating means for melting or softening a non-crosslinked portion of the at least one photopolymer layer;
c) at least one rotatable roll capable of bringing a wiping material into contact with the at least one photopolymer layer and removing a melted or softened non-crosslinked portion of the at least one photopolymer layer. A nip is formed between the means for supporting the relief image printing element and the at least one rotatable roll, wherein the at least one rotatable roll is relative to the relief image printing element. A roll that, upon rotation, transfers the melted or softened uncrosslinked portion of the at least one photopolymer layer from the printing element to the wipe;
d) with a scraping means arranged adjacent to the at least one rotatable roll to remove non-crosslinked photopolymer left on the surface of the at least one rotatable roll after step c) With a doctor blade;
Relates to an apparatus including

  As described herein, scraping means are used to remove photopolymer residues from a rotatable roll of a thermal processing apparatus. The scraping means is the rear position where the used wiping material is separated from the at least one rotatable roll, but the position where the unclean nonwoven blotter first contacts the at least one rotatable roll. It is positioned more forward. The scraping means preferably causes any debris scraped from the at least one rotatable roll to fall onto the used wiping material and get caught in the wiping material used for disposal Are arranged as follows. The scraping means may be a doctor blade or block shaped to be fixed against the surface of at least one rotatable roll. Preferably, the scraping means is a doctor blade.

  The use of scraping means causes the wiping material to adhere to at least one rotatable roll or, in extreme cases, to provide a textured surface to the processed plate, the photo on at least one rotatable roll By preventing the accumulation of polymer material, the function of the thermal processing apparatus is improved.

  One advantage of the use of the scraping means is that the photopolymer left on the hot surface of the at least one rotatable roll by the scraping means functioning continuously during operation of the thermal processing apparatus. It is to reduce the amount of residue. This reduces the tendency for photopolymer residues to decompose and make cleaning difficult. Also, since the doctor blade is a passive device, it does not require any operational changes to function.

  The thermal processing apparatus 10 of the present invention includes means for supporting the relief image printing element 20. As shown in FIG. 1, the means for supporting a relief image printing element 20 includes a conveyor 12 including a plurality of rolls 16 and a continuous loop 14 disposed around the rolls 18. If necessary, one or more additional rollers (not shown) are used to additionally support the conveyor 12 and prevent the continuous loop 14 from sagging due to the weight of the relief image printing element 20. Also good. In one embodiment, the continuous loop 14 comprises a wire mesh. The relief image printing element 20 may be held on the conveyor 12 by various means such as clamping, suction, or friction. In an alternative embodiment, the relief image printing element is in the form of a continuous in-the-round (CITR) photopolymer sleeve, and the means for supporting the CITR photopolymer sleeve includes a printing cylinder. Other means for supporting the relief image printing element 20 are also known to those skilled in the art.

  In order to improve the softening / melting efficiency of the non-crosslinked photopolymer and further soften and liquefy a portion of the at least one layer of photopolymer material, the heating means for melting or softening the non-crosslinked photopolymer comprises at least one An auxiliary heater 22 may be included disposed in at least one of the pre-tropics in front of the one rotatable roll 24 and the pre-tropics adjacent to the at least one rotatable roll 24. While various types of heaters can be used, preferably the auxiliary heater is an infrared heater.

  Also, while the relief image printing element 20 is in contact with at least one rotatable roll through the wipe, the at least one rotatable roll 24 is preferably heated to about 120 ° C. to about 200 ° C. Maintained at a temperature of ° C. This allows at least one rotatable roll 24 to melt or soften the non-crosslinked photopolymer or to melt and soften and remove the melted or softened photopolymer from the surface of the relief image printing element 20. It becomes.

  At least one rotatable roll 24 brings the wiping material 26 into contact with at least one photopolymer layer of the relief image printing element 20 to remove the melted or softened uncrosslinked portion of the at least one photopolymer layer. A nip 28 is formed between the means for supporting the relief image printing element 20 and the at least one rotatable roll 24, the at least one rotatable roll 24 being a relief image print. When rotated relative to the element 20, the melted or softened uncrosslinked portion of at least one photopolymer layer is transferred from the printing element 20 to the wipe 26.

  The wiping material 26 is supplied from the supply roll 30 of the wiping material 26 to the at least one rotatable roll 24, and the wiping material 26 is supplied from the supply roll 30 to the at least one rotatable roll 24. Supplied around the outer surface, the wiping material 26 first contacts the at least one rotatable roll 24 at a position in front of the nip 28 and at least one rotatable roll 24 at a position behind the nip 28. Separated from. The wipe 26 is wound around and under at least a portion of at least one rotatable roll 24 that contacts the imaged surface of the relief image printing element 20. Unused wiping material 26 is continuously fed from the web supply roll 30 of the wiping material 26 to the surface of at least one rotatable roll 24.

  The apparatus described herein also includes a winding roll 32 that winds, for disposal, a wiping material 26 that includes a melted or softened uncrosslinked portion of at least one photopolymer layer. The winding roll 32 may be a belt that is independently driven by a motor (not shown) such as a variable speed motor. The take-up roll 32 collects the web of the wiping material 26 after removing the portion of the photopolymer layer that has contacted the relief image printing element 20 and has been liquefied or softened. An automatic slicing device (not shown) may be used to replace the supply roll 30 of the wiping material 26 with an unused roll of wiping material 26.

  The apparatus described herein also includes at least one rotatable roll for removing non-crosslinked photopolymer left on the surface of at least one rotatable roll 24 after the wiping process has been performed. 24 includes an element (scraping means) arranged adjacent to 24. In a preferred embodiment, the element includes a doctor blade 34. Doctor blade 34 scrapes uncrosslinked photopolymer from the surface of at least one rotatable roll 24. This feature can be best observed in FIG.

  As shown in FIG. 2, uncrosslinked photopolymer 38 left on the surface of at least one rotatable roll 24 can be removed by a doctor blade 34. The doctor blade 34 is positioned on the take-up roll 32 after the wipe 26 is separated from the at least one rotatable roll 24 to deposit the non-crosslinked photopolymer 38 on the wipe 26. Is positioned.

  The doctor blade 34 is in a rear position where the wiping material 26 is separated from the at least one rotatable roll 24 and forward of the position where the wiping material 26 first contacts the at least one rotatable roll 24. Is arranged.

  In a preferred embodiment, the doctor blade 34 comprises a flexible material and may be a rigid plate (ie, Teflon®) covered with a polyurethane resin, a metal sheet, or a non-stick coating such as polytetrafluoroethylene. it can. Other materials for the doctor blade 34 are also known to those skilled in the art.

  The doctor blade 34 is connected to the blade holder 40 in order to enable adjustment and / or replacement of the doctor blade 34 as required. Since the blade holder 40 supports the doctor blade 34 to position the tip of the doctor blade 34 and contact the surface of the at least one rotatable roll 24, the doctor blade 34 is at least one rotatable. The non-crosslinked photopolymer 38 on the surface of the roll 24 can be scraped onto the wiping material 26 for disposal.

  As shown in the drawings, the doctor blade 34 is generally desirably positioned at an angle relative to the at least one rotatable roll 24 to facilitate removal of the non-crosslinked photopolymer 38. Although the angle is not critical to the present invention, in one embodiment, the doctor blade 34 is positioned at an angle of less than about 90 ° relative to the at least one rotatable roll 24.

  Finally, the wipe 26 is typically selected from the group consisting of screen mesh, woven fabric, non-woven fabric, and paper. As long as the fabric can withstand the operating temperature involved, either woven or non-woven fabric is used and the fabric can be polymer or paper. The choice of wipe is somewhat dependent on the thickness of the photosensitive printing element being processed, the melting temperature of the wipe, and the heat transfer characteristics of both the photosensitive printing element and the wipe. In one embodiment, the wiping material 26 is a non-woven wiping material such as a non-woven fabric.

  The apparatus described herein also preferably includes means for maintaining contact between the at least one roll 24 and the relief image printing element 20. The means for maintaining contact may include an air cylinder or a hydraulic cylinder that presses at least one roll 24 against the imaged surface of the relief image printing element 20. Other means for maintaining contact between the at least one roll 24 and the relief image printing element 20 are also known to those skilled in the art.

The present invention also generally relates to a method of thermally processing a relief image printing element using the apparatus described herein. As described above, the relief image printing element comprises a backing layer and at least one photopolymer layer disposed on the backing layer, wherein the relief image printing element is selectively exposed to actinic radiation. A portion of the at least one photopolymer layer is crosslinked and a portion of the at least one photopolymer layer is not crosslinked without being exposed to actinic radiation. The method generally includes:
a) melting or softening a non-crosslinked portion of the at least one photopolymer layer;
b) creating contact between the surface of the relief image printing element and a wiping material disposed on a portion of the at least one rotatable roll, the at least one rotatable roll; When rotating, the wiping material comes into contact with at least part of the surface of the at least one photopolymer layer, and the melted or softened non-crosslinked portion of the at least one photopolymer layer is the wiping material. The process of being transferred to
c) scraping the at least one rotatable roll after step b) to remove uncrosslinked photopolymer left on the at least one rotatable roll;
including.

  As described herein, scraping at least one rotatable roll and removing the non-crosslinked photopolymer places a doctor blade 34 adjacent to the surface of the at least one rotatable roll 24. The tip of the doctor blade 34 contacts the surface of the at least one rotatable roll 24 to move the non-crosslinked photopolymer 38 from the surface of the at least one rotatable roll 24 onto the wiping material 26. And a scraping step.

In another embodiment, the present invention is also generally an apparatus for thermally processing a relief image printing element, the relief image printing element comprising at least one photopolymer layer, wherein the relief image printing The element is selectively exposed to actinic radiation so that a portion of the at least one photopolymer layer is crosslinked while a portion of the at least one photopolymer layer is crosslinked without exposure to actinic radiation. not,
a) means for supporting the relief image printing element;
b) a heating means for melting or softening a non-crosslinked portion of the at least one photopolymer layer;
c) at least one rotatable roll disposed adjacent to the means for supporting the relief image printing element and removing a melted or softened uncrosslinked portion of the at least one photopolymer layer, A nip is formed between the means for supporting the relief image printing element and the at least one rotatable roll, and the at least one rotatable roll rotates relative to the relief image printing element. A roll in which a melted or softened non-crosslinked portion of the at least one photopolymer layer is transferred from the relief image printing element to the surface of the at least one rotatable roll;
d) adjacent to the at least one rotatable roll for scraping off the melted or softened non-crosslinked portion of the transferred at least one photopolymer layer from the surface of the at least one rotatable roll; Scraping means disposed at a rear position of the nip;
e) a waste container arranged to contain the non-crosslinked photopolymer scraped from the surface of the at least one rotatable roll;
The present invention relates to an apparatus including:

  As shown in FIG. 3, instead of the molten or softened uncrosslinked photopolymer being transferred to the wipe, the rotatable roll 24 itself removes the melted or softened uncrosslinked photopolymer. Accordingly, molten or softened non-crosslinked photopolymer 38 is transferred from the relief image printing element 20 to the at least one rotatable roll 24 at the heating nip 28. A doctor blade 34 (preferred scraping means) is disposed at a rearward position of the nip 28 adjacent to the at least one rotatable roll 24 and causes the non-crosslinked photopolymer 38 to be on the surface of the at least one rotatable roll 24. Scrape into the waste container 42. An advantage of this embodiment of the present invention is that this “no wipe” system significantly reduces the waste produced by the thermal processing system.

  As described herein, the heating nip 28 is used to transfer non-crosslinked photopolymer from the imaged relief image printing element to the surface of at least one rotatable roll, preferably about 120. C. to about 200.degree. C. Thereafter, a doctor blade 34 is used to remove photopolymer residues from the hot rolls of the thermal processing apparatus. The blade is positioned behind the heating nip. The doctor blade 34 is also arranged in such a way that any debris scraped from the at least one roll 24 falls into a disposal container 42 for disposal.

  Such use of the doctor blade 34 improves the function of the thermal processing apparatus and at the same time significantly reduces the complexity of the thermal processing apparatus.

The present invention also generally relates to a method of thermally processing a relief image printing element using the apparatus described herein. As described above, the relief image printing element comprises a backing layer and at least one photopolymer layer disposed on the backing layer, wherein the relief image printing element is selectively exposed to actinic radiation. A portion of the at least one photopolymer layer is crosslinked and a portion of the at least one photopolymer layer that is not exposed to actinic radiation is not crosslinked. The method generally includes:
a) melting or softening a non-crosslinked portion of the at least one photopolymer layer;
b) creating contact between the surface of the relief image printing element and at least one rotatable roll, the means for supporting the relief image printing element and the at least one rotatable roll; When the at least one rotatable roll rotates relative to the relief image printing element, the melted or softened non-crosslinked portion of the at least one photopolymer layer is Transferring from a relief image printing element to the surface of the at least one rotatable roll;
c) scraping the at least one rotatable roll after step b) to remove uncrosslinked photopolymer left on the at least one rotatable roll;
including.

  Accordingly, the present invention provides an improved apparatus for thermal processing of relief image printing elements that improves the cleaning of hot rolls and eliminates the need for wipes for removal of uncrosslinked photopolymer. I understand that it provides.

Claims (7)

An apparatus for thermally processing a relief image printing element, wherein the relief image printing element comprises at least one photopolymer layer, wherein the relief image printing element is selectively exposed to actinic radiation to produce the at least one A portion of the photopolymer layer of the layer is crosslinked, and at the same time, a portion of the at least one photopolymer layer is not crosslinked without being exposed to actinic radiation,
a) means for supporting the relief image printing element;
b) a heating means for melting or softening a non-crosslinked portion of the at least one photopolymer layer;
c) Rotating to remove the melted or softened uncrosslinked portion of the at least one photopolymer layer disposed adjacent to the means for supporting the relief image printing element and disposed behind the heating means A nip is formed between the means for supporting the relief image printing element and the rotatable roll, and the rotatable roll rotates relative to the relief image printing element. The rotatable roll in which the melted or softened non-crosslinked portion of the at least one photopolymer layer is transferred from the relief image printing element to the surface of the rotatable roll , and covered with a wiping material. The rotatable roll wherein the melted or softened non-crosslinked portion of the photopolymer layer is not directly transferred to the surface of the rotatable roll ;
d) at a rear position of the nip adjacent to the rotatable roll for scraping off the melted or softened non-crosslinked portion of the transferred at least one photopolymer layer from the surface of the rotatable roll. Arranged doctor blades;
e) a waste container arranged to contain the non-crosslinked photopolymer scraped from the surface of the rotatable roll;
The apparatus characterized by including. It said rotatable roll apparatus according to claim 1 which is maintained at a temperature of 1 20 ℃ ~2 00 ℃.   The apparatus of claim 1, further comprising an auxiliary heater disposed adjacent to a conveyor and the hot roll to further soften the uncrosslinked portion of the at least one photopolymer layer.   The doctor blade is detachably connected to a blade holder, and the blade holder positions the tip of the doctor blade and supports the doctor blade so as to contact the surface of the rotatable roll. The apparatus of claim 1. The doctor blade apparatus of claim 1, which is disposed at an angle of less than 9 0 ° with respect to the roll. A method of thermally processing a relief image printing element, wherein the relief image printing element comprises a backing layer and at least one photopolymer layer disposed on the backing layer, the relief image printing element comprising: A portion of the at least one photopolymer layer is selectively exposed to actinic radiation to crosslink, a portion of the at least one photopolymer layer is not exposed to actinic radiation and is not crosslinked,
a) melting or softening a non-crosslinked portion of the at least one photopolymer layer;
b) creating a contact between the surface of the relief image printing element and a rotatable roll, wherein a nip is provided between the means for supporting the relief image printing element and the rotatable roll. Formed, and when the rotatable roll rotates relative to the relief image printing element, a melted or softened non-crosslinked portion of the at least one photopolymer layer is rotatable from the relief image printing element. Transferred to the surface of the roll, the rotatable roll is not covered with a wiping material, and the melted or softened non-crosslinked portion of the photopolymer layer is transferred directly to the surface of the rotatable roll. And a process of
c) removing the molten or softened uncrosslinked photopolymer left on the rotatable roll by scraping the rotatable roll with a doctor blade after step b);
A method comprising the steps of:   The method of claim 6, further comprising depositing the non-crosslinked photopolymer scraped from the rotatable roll into a waste container.