JP4879856B2 - Lithographic printing plate developer evaluation method and planographic printing plate quality control method - Google Patents

Description

  The present invention relates to a developer evaluation method for a lithographic printing plate and a quality control method for a lithographic printing plate, and more specifically, a photosensitive lithographic printing plate precursor for so-called direct plate making that can be directly made from a digital signal of a computer or the like. The present invention relates to a developer evaluation method and a quality control method suitable for the above.

  In the printing / plate making industry, a standard image used for production management of printing is called a control strip, and in many cases, a control strip is printed as a small standard image on a vacant portion of an end portion of an image necessary as printed matter. Using this control strip as a reference, the finish in the plate making / printing process is checked by visual inspection or density measurement, and the result is fed back to the previous process for quality control.

On the other hand, in recent years, an infrared laser has been frequently used as an exposure light source when directly making a plate from digital data of a computer or the like. In such a negative planographic printing plate for an infrared laser, the latitude for the activity of the developer in the image recording layer is generally narrow, and process management is important in order to continuously form stable images. Usually, when developing a photosensitive lithographic printing plate precursor, an automatic processor having a replenishment mechanism that keeps the developer sensitivity as constant as possible is used, and the pH of the developer is lowered to reduce developability. In order to prevent this, a method of adding a highly active replenisher is used (for example, see Patent Document 1).
However, as described above, positive lithographic printing plates for infrared lasers have a narrow latitude, so that the image formability varies greatly due to changes in the activity of the developer, and the developability can be increased by adding a highly active replenisher. This is likely to cause problems in the quality of the lithographic printing plate, such as defects in the image area or undesired development of halftone dots and fine lines.

In recent years, there has been an increasing demand for obtaining a higher-definition image, and for that purpose, it is necessary to stabilize the formation of halftone dots in details. It has become a bigger problem than before. Therefore, a standard image pattern (control strip) suitable for evaluating the halftone dot formability in the lithographic printing plate precursor as described above, and a developer evaluation method for keeping the halftone dot formability constant And quality control methods are strongly desired.
JP-A-8-44076

An object of the present invention is to solve the above problems and achieve the following object.
That is, the first object of the present invention is to provide a lithographic printing plate developer evaluation method capable of accurately evaluating the activity of a developer.
The second object of the present invention is to accurately evaluate the activity of the developer and feed back the results to the exposure and / or development process, thereby maintaining the quality of the lithographic printing plate and continuously producing a uniform image. It is an object of the present invention to provide a quality control method for a lithographic printing plate that can be formed on a plate.

  As a result of the study, the inventors of the present invention arranged two types of halftone dots close to each other and used a standard image pattern in which both of the halftone dots were changed stepwise to perform exposure under specific conditions. After making a lithographic printing plate under standard conditions, make a similar lithographic printing plate under the conditions to be evaluated, and compare the two to easily evaluate the formed image. It was found that the quality control of the lithographic printing plate can be easily performed by feeding back the evaluation result and the evaluation result, and the present invention has been completed.

That is, the configuration of the present invention is as follows.
The developer evaluation method for a lithographic printing plate of the present invention uses a developer used for an infrared-sensitive lithographic printing plate precursor having a photosensitive layer containing an infrared absorber, a polymerizable compound, and a polymerization initiator, as described below (A ), (B), (C), and (D).
(A) A predetermined area ratio using a plurality of AM halftone images having different area ratios by the AM screen method and circular dots having a diameter of 10 μm to 75 μm adjacent to each of the plurality of AM halftone images. An infrared-exposed plate obtained in steps (B) and (A) of exposing an infrared-sensitive lithographic printing plate precursor to a standard image pattern comprising an FM halftone image using an FM screen system having Step (C) for developing a standard plate by developing in (A) A step (D) for developing an infrared-exposed plate according to (A), which is different from (B), and preparing a target developer evaluation plate (D) ) A step of comparing halftone dot area ratios of the standard plate and the target development evaluation plate

  In the developer evaluation method for a lithographic printing plate according to the present invention, the AM halftone image is a halftone image having a screen line number of 80 lines / inch to 300 lines / inch, and the FM halftone image has an area ratio of 30. It is a preferable embodiment that the image is a halftone dot image in the range of 70% to 70%.

The quality control method for a lithographic printing plate according to the present invention comprises the following (A) and (A) when making an infrared-sensitive lithographic printing plate precursor having a photosensitive layer containing an infrared absorber, a polymerizable compound, and a polymerization initiator. B), (C), (D), and (E) are managed by the process.
(A) A predetermined area ratio using a plurality of AM halftone images having different area ratios by the AM screen method and circular dots having a diameter of 10 μm to 75 μm adjacent to each of the plurality of AM halftone images. An infrared-exposed plate obtained in steps (B) and (A) of exposing an infrared-sensitive lithographic printing plate precursor to a standard image pattern comprising an FM halftone image using an FM screen system having Step (C) for developing a standard plate by developing in (A) A step (D) for developing an infrared-exposed plate according to (A), which is different from (B), and preparing a target developer evaluation plate (D) ) Steps (E) and (D) of comparing the halftone dot area ratios of the standard plate and the target development evaluation plate. Is greater than or equal to Adjusting exposure conditions and / or development conditions

  In the quality control method for a lithographic printing plate of the present invention, the step of replacing the plate exposed and developed under the conditions adjusted in the steps (F) and (E) with the target developer evaluation plate in the step (C). Furthermore, it is a preferable aspect that the steps (F), (D), and (E) are repeated one or more times in this order.

ADVANTAGE OF THE INVENTION According to this invention, the developing solution evaluation method of the lithographic printing plate which can evaluate the activity of a developing solution correctly can be provided.
Further, according to the present invention, the activity of the developer is accurately evaluated, and the result is fed back to the exposure and / or development process, so that the quality of the lithographic printing plate can be kept constant and a uniform image can be continuously obtained. A quality control method for a lithographic printing plate that can be formed can be provided.

Hereinafter, the present invention will be described in more detail.
<Developer Evaluation Method for Planographic Printing Plate>
The developer evaluation method for a lithographic printing plate of the present invention uses a developer used for an infrared-sensitive lithographic printing plate precursor having a photosensitive layer containing an infrared absorber, a polymerizable compound, and a polymerization initiator, as described below (A ), (B), (C), and (D).
(A) A predetermined area ratio using a plurality of AM halftone images having different area ratios by the AM screen method and circular dots having a diameter of 10 μm to 75 μm adjacent to each of the plurality of AM halftone images. An infrared-exposed plate obtained in steps (B) and (A) of exposing an infrared-sensitive lithographic printing plate precursor to a standard image pattern comprising an FM halftone image using an FM screen system having Step (C) for developing a standard plate by developing in (A) A step (D) for developing an infrared-exposed plate according to (A), which is different from (B), and preparing a target developer evaluation plate (D) ) A step of comparing halftone dot area ratios of the standard plate and the target development evaluation plate

The quality control method for a lithographic printing plate according to the present invention is such that the results of the developer evaluation method according to the present invention are fed back to adjust exposure and / or development conditions.
That is, the quality control method for a lithographic printing plate according to the present invention comprises the following (A) when making an infrared-sensitive lithographic printing plate precursor having a photosensitive layer containing an infrared absorber, a polymerizable compound, and a polymerization initiator. , (B), (C), (D), and (E).
(A) A predetermined area ratio using a plurality of AM halftone images having different area ratios by the AM screen method and circular dots having a diameter of 10 μm to 75 μm adjacent to each of the plurality of AM halftone images. An infrared-exposed plate obtained in steps (B) and (A) of exposing an infrared-sensitive lithographic printing plate precursor to a standard image pattern comprising an FM halftone image using an FM screen system having Step (C) for developing a standard plate by developing in (A) A step (D) for developing an infrared-exposed plate according to (A), which is different from (B), and preparing a target developer evaluation plate (D) ) Steps (E) and (D) of comparing the halftone dot area ratios of the standard plate and the target development evaluation plate. Is greater than or equal to Adjusting exposure conditions and / or development conditions

  In the planographic printing plate quality control method of the present invention, the plate exposed and developed under the conditions adjusted in the steps (F) and (E) is replaced with the target developer evaluation plate in the step (C). It is a preferable aspect that the method further includes a step, and the steps (F), (D), and (E) are repeated one or more times in this order.

First, the standard image pattern used in the step (A) of the present invention will be described.
An FM screen is an abbreviation for Frequency Modulation Screening, and is a printing method using a halftone dot pattern using a frequency modulation technique, and expresses light and shade by the density of dots.
This FM screen expresses the density of a recorded image by the density of irregularly shaped dots having no regularity, and is composed of relatively small and small dots such as 2 × 2 total 4 dots. Gradation is expressed by dispersing an image in a two-dimensional plane.

On the other hand, in the AM screen which is another halftone image used in the standard image pattern in the present invention, a halftone dot, that is, a regular halftone dot in a so-called minimal checkered pattern is used.
In this AM screen, the halftone dot image of the minimum unit is composed of a relatively large number of minute dots such as a total of 196 dots of 14 (the number of dots in the horizontal direction) × 14 (the number of dots in the vertical direction) as an example. A grayscale image is formed by recording halftone images in a two-dimensional plane, and gradation expression is performed.
Usually, such an AM screen (AM network) or FM screen (FM network) expresses a halftone, but in order to print a high-definition printed matter, a high-definition and uniform AM screen over the entire surface of the lithographic printing plate. In addition, it is necessary to form a halftone dot image of an FM screen, and density control of these is important for quality control of printed matter.

The standard image pattern (control strip) used in the present invention has a plurality of AM halftone images having different area ratios in an AM screen system in stages, and is adjacent to each of the plurality of AM halftone images and has a diameter of 10 μm to 75 μm. And an FM halftone dot image using an FM screen system having a predetermined area ratio.
That is, the standard image pattern according to the present invention includes an AM halftone image of an image chart continuously arranged by changing the area ratio stepwise, and an FM having a certain area ratio arranged in proximity to each AM halftone image. It consists of a combination with a halftone image.
The AM halftone dot image forming area and the FM halftone dot image forming area which are formed adjacent to each other can be arbitrarily selected as long as the above conditions are satisfied.

Specific examples showing the formation area of the AM halftone image and the FM halftone image of the standard image pattern in the present invention will be described below, but the present invention is not limited to the following specific examples.
FIG. 1A to FIG. 1C are model diagrams showing an AM dot image forming region 12 and an FM dot image forming region 14 formed adjacent to each other in the standard image pattern 10 according to the present invention. It is. In FIG. 1A to FIG. 1C, the AM dot image formation region 12 is indicated by diagonal lines, and the FM dot image formation region 14 is indicated by halftone dots. In this drawing, no. 0-No. Although an aspect in which 30 steps are changed in 31 steps is shown, the number of step changes can be appropriately determined according to the purpose, such as required evaluation accuracy.
For example, as shown in FIG. 1A, a circular area is formed near the center of a rectangular area, and an AM halftone dot is formed in the surrounding rectangular area. An image is formed, and an FM halftone image is formed in a central circular area. As shown in FIG. 1B, a rectangular area is divided into two by a straight line, and an AM halftone image is formed in one area. And an FM halftone dot image is formed in the other region, as shown in FIG. 1C, a rectangular region having a different area is formed near the center of the rectangular region, and the surrounding rectangular region In other words, an AM halftone dot image is formed in the middle rectangular area, and an FM halftone dot image is formed in a central rectangular area.
As shown in FIGS. 1A to 1C, a plurality of sets of halftone dot regions having different area ratios are formed, and the standard image pattern in the present invention is configured.

In particular, as shown in FIG. 1A, it is preferable from the viewpoint of easy viewing that the FM halftone image is formed in a circular area at the center and the peripheral area is an AM dot image forming area.
In consideration of the minimum measurement area of the densitometer, it is preferable that at least one piece is 7 mm or more in the case of a rectangle and the diameter is 7 mm or more in the case of a circle.

The FM halftone dot image having a certain area ratio needs to be a halftone dot image formed by randomly arranging circular dots having a diameter of about 10 to 75 μm. Further, the area ratio of the FM halftone image formed at a predetermined area ratio is preferably set to about 30% to 70%.
Further, an AM halftone image formed close to an FM halftone image having a certain area ratio is a halftone dot having a specific line number in the range of 80 lines / inch to 300 lines / inch. Is preferred. As a change in the area ratio, it is preferable to set the minimum value to about 30% as a standard and the maximum value to about 60% as a standard. Accordingly, it may be changed step by step in increments of 0.5% to 5%, typically in increments of 1%.

  If a photosensitive lithographic printing plate precursor is made using a standard image pattern in which FM halftone images and AM halftone images are arranged adjacent to each other under such conditions, the influence of development conditions etc. on the halftone quality after plate making. Since it is reflected extremely sensitively and the state of the developer can be easily detected visually, it is preferable from the viewpoint of the effect of the present invention.

  An FM screen system having a predetermined area ratio using a plurality of AM halftone images having different area ratios in stages and circular dots having a diameter of 10 μm to 75 μm adjacent to each of the plurality of AM halftone images. When a standard image pattern provided with an FM halftone image according to the above is used, an area in which both adjacent halftone dot images are visually judged to have the same density after making a plate is defined as a “comparison point”. It is possible to accurately determine the activity of the. That is, by comparing the halftone dot area ratio (halftone dot%) at the reference point of the reference plate with the halftone dot area ratio (halftone dot%) at the comparison point of the target development evaluation plate, Changes can be confirmed.

Hereinafter, steps (A) to (D) in the developer evaluation method of the present invention and steps (A) to (F) in the quality control method of the present invention will be described in order.
In the step (A), the above-described standard image pattern in the present invention is exposed to infrared light on the photosensitive lithographic printing plate precursor.
The formation of halftone dots in the step (A) may be performed on a part of the surface area of one lithographic printing plate precursor. For example, about 20% may be used as a halftone dot formation region, partially and at a plurality of locations. May be used as a halftone dot formation region.

In step (B), the infrared-exposed plate according to (A) is developed with a standard developer to produce a standard plate.
The prepared standard plate is a standard sample of the development conditions that serve as a base, and the formulation of the developer, the processing time, the processing temperature, and the like used here are adopted as standard steps. Note that the standard version, which is the evaluation standard, does not need to be prepared for each evaluation. If the evaluation and management are to be performed in a continuous process in which the same plate-making process is performed, only one sheet is required at the initial stage. What is necessary is just to produce.

Subsequently, in the step (C), an infrared-exposed plate according to (A) different from (B) is developed with a developer to be evaluated to produce a target developer evaluation plate.
The target developer evaluation plate prepared in this step is for confirming the state of fatigue of the developer after the lapse of time. At the time when evaluation is required, the standard plate is prepared in step (A). It is obtained by processing the same photosensitive lithographic printing plate precursor as used. At this time, the development processing temperature, processing time, and the like are applied under the same conditions as in the case where the standard plate is produced in the step (A).

In the step (D), the halftone dot area ratio (halftone dot%) is compared between the standard plate produced in the step (B) and the target development evaluation plate produced in the step (C).
In this way, the active state of the developer can be evaluated by comparing the sample that has been subjected to standard development processing (standard version) and the sample to be evaluated (target development evaluation plate). Here, the halftone dot area ratio to be compared may be the halftone dot area ratio at the comparison point between the standard plate and the target development evaluation plate.
Specifically, for example, when the standard image patterns shown in FIGS. 1A to 1C are used, the density of the FM halftone image by the FM screen and the density of the AM halftone image by the surrounding AM screen And No. that match. (Corresponding to the aforementioned “comparison point”) is read visually. Thus, No. confirmed visually. By comparing the halftone dot area ratio (halftone dot%) between the reference plate and the target development evaluation plate, it can be confirmed whether or not the active state of the developer is changed.

In the present invention, a photosensitive lithographic printing plate precursor on which an AM halftone image and an FM halftone image are formed may be separately prepared and used as a lithographic printing plate precursor for evaluation.
That is, this evaluation planographic printing plate precursor is placed at a predetermined interval between other planographic printing plate precursors to be plate-made in an apparatus in which general plate making processing is performed, and the evaluation planographic printing plate Evaluation and management can be performed by checking the plate making state of the original plate. In addition, an evaluation is made by forming an AM halftone image and an FM halftone image on the blank portion of the lithographic printing plate precursor, which is the product to be made, that is, the frame portion of the lithographic printing plate precursor, and confirming the platemaking state. And can be managed.

  In the quality control method of the present invention, as a result of the evaluation in the steps (A) to (D) in the developer evaluation method of the present invention, the difference in the dot area ratio (halftone dot%) between the standard plate and the target development evaluation plate is And a step of adjusting exposure / development conditions (step (E)) when the value is equal to or greater than a predetermined value. That is, the quality control method of the present invention rationally controls the quality of the lithographic printing plate by adjusting the exposure process / development process by feeding back the evaluation result obtained by the developer evaluation method of the present invention. Is a way that can be.

In the step (E), as a result of the comparison in (D), when the difference in the halftone dot area ratio between the standard plate and the target development evaluation plate is a predetermined value or more, the exposure condition and / or the development condition are adjusted.
The predetermined value in this step (E) (that is, the difference in halftone dot%) may be appropriately determined depending on the quality desired for the lithographic printing plate precursor to be used. In general, when the difference in the halftone dot area ratio (halftone dot%) between the standard plate and the target development evaluation plate is 2.0% or more, it is a guideline for feedback. That is, when the halftone dot area ratio (halftone dot%) at the reference point of the reference plate and the halftone dot area ratio (halftone dot%) at the comparison point of the target development evaluation plate are 2.0% or more, It is a measure of feedback.

The means for adjusting the exposure conditions and / or development conditions in the step (E) are as follows.
In the case where a decrease in developability is observed in the evaluated development evaluation plate, that is, when the halftone dot percentage increases, a means for lowering the exposure condition or activating the development condition may be employed. Further, when the image is excessively developed, that is, when the halftone dot percentage is lowered, a means for increasing the exposure condition or relaxing the development condition may be employed.

  The following measures can be taken as countermeasures when the difference in halftone dot percentage exceeds a predetermined value due to excessive development.

<Means Applied to Adjustment in Development Process>
(1) Add water to the developer.
(2) Add dry ice to the developer.
(3) Blow CO ₂ gas.
(4) Reduce the dilution ratio of the replenisher.
(5) Reduce the replenishment amount setting of the automatic processor.
(6) Lower the development temperature.
(7) Shorten the development time (increase the conveyance speed of the automatic processor).
(8) Lower the pressure of the developing brush of the automatic processor.
(9) Reduce the number of developing brushes in the automatic processor.
(10) Lower the spray discharge amount.
(11) Stir the developer.
(12) Replace the developer with a new solution.

<Means Applied to Adjustment in Exposure Process>
(13) Increase the exposure amount.

  On the other hand, the following means can be cited as countermeasures when the difference in halftone dot percentage exceeds a predetermined value due to a decrease in developability.

<Means Applied to Adjustment in Development Process>
(1) Add replenisher.
(2) Increase the dilution ratio of the replenisher.
(3) Increase the replenishment amount setting of the automatic processor.
(4) Increase the development temperature.
(5) Increase the development time (lower the conveyance speed of the automatic processor).
(6) Increase the pressure of the developing brush of the automatic processor.
(7) Increase the number of developing brushes in the automatic processor.
(8) Increase the spray discharge amount.
(9) Replace the developer with a new solution.

<Means Applied to Adjustment in Exposure Process>
(10) Decrease the exposure amount.

  In the above adjustment means, when the exposure amount is controlled, conditions such as the output of the laser beam, the beam diameter, the scanning speed, and the exposure time may be appropriately adjusted.

Furthermore, in the quality control method of the present invention, after completion of the steps (A) to (E), as a step (F), a plate subjected to exposure and development under the conditions adjusted in the step (E), It is preferable that the method further includes a step of replacing the target developer evaluation plate in the step (C), and the steps (F), (D), and (E) are repeated one or more times in this order.
As described above, by repeatedly feeding back the evaluation result of the active state of the developer to the exposure / development conditions, the plate-making state of the planographic printing plate can be stably maintained for a long period of time. .

[Photosensitive planographic printing plate precursor]
Hereinafter, the photosensitive lithographic printing plate precursor applied to the developer evaluation method of the present invention and the quality control method of the present invention will be described in detail.
The photosensitive lithographic printing plate precursor to be evaluated in the present invention is not particularly limited as long as it has a photosensitive layer containing an infrared absorber, a polymerizable compound, and a polymerization initiator. A lithographic printing plate used for printing is obtained by exposing and developing the original plate.
Hereinafter, the elements constituting the photosensitive lithographic printing plate precursor used in the present invention will be described.

(Photosensitive layer)
The photosensitive layer in the photosensitive lithographic printing plate precursor used in the present invention contains an infrared absorber, a polymerizable compound, and a polymerization initiator, and further contains a binder polymer, a colorant, and other optional components as necessary. .

-Infrared absorber-
The infrared absorber contained in the photosensitive layer in the present invention is useful for causing a chemical change with high sensitivity by a polymerization initiator because thermal energy is generated by a photothermal conversion function upon irradiation (exposure) of an infrared laser. It is.
Particularly preferred infrared absorbers used in the present invention include dyes having an absorption maximum at a wavelength of 750 nm to 1400 nm. Preferred dyes include cyanine dyes, squarylium dyes, pyrylium salts, nickel thiolate complexes, and indolenine cyanine dyes. Preferred examples are described in paragraphs [0017] to [0019] of JP-A No. 2001-133969. And cyanine dyes.

-Polymerizable compound-
The polymerizable compound contained in the photosensitive layer in the invention can be arbitrarily selected from compounds having a terminal ethylenically unsaturated bond, and has a chemical form such as a monomer, a prepolymer, and a mixture thereof. .
Examples of monomers include esters of unsaturated carboxylic acids (eg, acrylic acid, methacrylic acid, itaconic acid, maleic acid) and aliphatic polyhydric alcohol compounds, amides of unsaturated carboxylic acids and aliphatic polyvalent amine compounds. Is mentioned. Preferably, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, or an amide of an unsaturated carboxylic acid and an aliphatic polyvalent amine compound is used. Urethane addition polymerizable compounds are also suitable.

-Polymerization initiator-
The polymerization initiator contained in the photosensitive layer in the present invention has a function of initiating and advancing the curing reaction of the polymerizable compound described above, and is a thermal decomposition type radical generator that decomposes by heat to generate radicals, infrared absorption Giving energy, such as an electron transfer type radical generator that generates radicals by accepting excited electrons of an agent, or an electron transfer type radical generator that generates radicals by electron transfer to an excited infrared absorber Any compound may be used as long as it can generate a radical.
Specific examples include onium salts, active halogen compounds, oxime ester compounds, and borate compounds. In the present invention, onium salts, particularly sulfonium salts are preferred, and aromatic sulfonium salts are particularly preferred.

-Binder polymer-
The binder polymer contained in the photosensitive layer in the present invention not only functions as a film-forming agent for the photosensitive layer, but also needs to dissolve the photosensitive layer in an alkaline developer, so that the organic polymer that is soluble or swellable in alkaline water is used. A molecular polymer is preferably used.
As such a binder polymer, those shown in paragraph numbers [0052] to [0060] of JP-A No. 2001-133969 are useful.

-Other ingredients-
In addition, for the photosensitive layer, additives shown in paragraph numbers [0061] to [0068] of JP-A No. 2001-133969 (for example, surfactants, colorants, plastics for improving coatability) It is also preferable to add various compounds such as an agent and a thermal polymerization inhibitor.

(Protective layer)
In the photosensitive lithographic printing plate precursor used in the present invention, an oxygen-blocking protective layer is preferably provided on the photosensitive layer in order to prevent the action of inhibiting the polymerization of oxygen.
Examples of the polymer contained in the protective layer include polyvinyl alcohol and copolymers thereof.
In the present invention, it is preferable to provide a protective layer as shown in paragraph numbers [0163] to [0187] of JP-A-2007-199647.

(Other layers)
Furthermore, the photosensitive lithographic printing plate precursor used in the present invention is subjected to silicate treatment, acid treatment, etc. as shown in paragraphs [0124] to [0165] of JP-A-2001-228608. It may be applied or may have an intermediate layer or an adhesive layer.

(Support)
The support for the photosensitive lithographic printing plate precursor used in the present invention is preferably one using an aluminum plate that can provide a surface excellent in hydrophilicity and strength by surface treatment.
The composition of the aluminum plate applied to the present invention is not specified, and conventionally known and used materials such as JIS A 1050, JIS A 1100, JIS A 3103, JIS A 3005, etc. are appropriately used. can do.
Moreover, the thickness of the aluminum support body used for this invention is about 0.1 mm-about 0.6 mm. This thickness can be changed as appropriate according to the size of the printing press, the size of the printing plate, and the desire of the user.

Such a support (aluminum support) is subjected to a surface treatment described later to be hydrophilized.
Examples of the roughening treatment method include mechanical roughening, chemical etching, and electrolytic grain as disclosed in JP-A-56-28893. Furthermore, an electrochemical surface roughening method in which the surface is electrochemically roughened in a hydrochloric acid or nitric acid electrolyte can be used. Among them, a method usefully used for the surface roughening is a hydrochloric acid or nitric acid electrolyte. an electrochemical method of chemically roughening suitable anode time electricity is in the range of ^{50C / dm 2 ~400C / dm 2} , AC and at a current density of 100C ^/ dm ² ~400C ^/ dm 2 It is preferable to perform direct current electrolysis.
The roughened aluminum support may be chemically etched with acid or alkali.

The aluminum support treated as described above may then be subjected to an anodizing treatment.
In the anodizing treatment, sulfuric acid, phosphoric acid, oxalic acid, or an aqueous solution of boric acid / sodium borate is used as a main component of the electrolytic bath singly or in combination. The thickness of the formed anodic oxide film is in the range of 0.5 to 1.5 μm.

  Further, the support surface may be further hydrophilized. As this hydrophilization treatment, widely known methods can be applied. A particularly preferred treatment is a hydrophilic treatment with silicate or polyvinylphosphonic acid.

(Undercoat layer)
The photosensitive lithographic printing plate precursor used in the present invention may be provided with an undercoat layer for the purpose of improving adhesion between the photosensitive layer and the support and stain resistance. Specific examples of such an undercoat layer include those described in JP-A No. 2000-10292, JP-A No. 2000-235254, JP-A No. 2000-352854, JP-A No. 2001-209170, and the like.

(Back coat layer)
The photosensitive lithographic printing plate precursor used in the present invention has a function of preventing adhesion between the original plates and a function of preventing scratches caused by rubbing the photosensitive layer or the protective layer when the original plates are laminated. Therefore, a back coat layer may be provided on the back surface of the support.
Specific examples of such a back coat layer include those described in JP-A No. 2001-133969 and layers containing a resin such as an epoxy resin.

[Plate making method]
Hereinafter, the plate making method of the photosensitive lithographic printing plate precursor used in the present invention will be described.
The photosensitive lithographic printing plate precursor used in the present invention forms a laminate formed by laminating a plurality of sheets in the same direction, and then the laminate is set in a plate setter, and the lithographic printing plate precursor is automatically printed one by one. The plate can be made by carrying out an exposure process and then a development process after carrying.
The laminate used here may be one in which a slip sheet is sandwiched between the plates, or depending on the type of the photosensitive lithographic printing plate precursor, the slip sheet is not used, and the surface on the photosensitive layer side and the back surface of the support May be laminated in direct contact with each other.

Depending on the type of the photosensitive lithographic printing plate precursor, the laminate as described above is set in a plate setter, and after the lithographic printing plate precursor is automatically conveyed one by one, it is exposed at a wavelength of 750 nm to 1400 nm. Thereafter, the development process can be performed under a condition that the conveyance speed is 1.25 m / min or more without substantially undergoing a heat treatment.
In the case where the photosensitive lithographic printing plate precursor is provided with a protective layer on the photosensitive layer and further provided with a backcoat layer on the back surface of the support, a plurality of sheets are obtained by directly contacting the protective layer and the backcoat layer. After the laminated body is set in a plate setter and the lithographic printing plate precursor is automatically conveyed one by one, after being exposed at a wavelength of 750 nm to 1400 nm, substantially without undergoing a heat treatment, It is possible to make a plate by carrying out development processing under a condition where the conveyance speed is 1.25 m / min or more.

(exposure)
As a light source used for the exposure processing in the present invention, a laser emitting infrared rays having a wavelength of 760 nm to 1200 nm can be used. As an available light source, a semiconductor laser (800 to 850 nm) and an Nd-YAG laser (1064 nm) can be preferably used. The laser output is preferably 100 mW or more, and a multi-beam laser device is preferably used in order to shorten the exposure time. The exposure time per pixel is preferably within 20 μsec. The amount of energy per unit irradiated on the lithographic printing plate precursor is preferably 10 to 300 mJ / cm ² .

  In the exposure processing in the present invention, exposure can be performed by overlapping light beams of light sources. Overlap means that the sub-scanning pitch width is smaller than the beam diameter. The overlap can be expressed quantitatively by FWHM / sub-scanning pitch width (overlap coefficient), for example, when the beam diameter is expressed by the half width (FWHM) of the beam intensity. In the present invention, the overlap coefficient is preferably 0.1 or more.

The scanning method of the light source of the exposure apparatus used in the present invention is not particularly limited, and a cylindrical outer surface scanning method, a cylindrical inner surface scanning method, a planar scanning method, or the like can be used. The channel of the light source may be a single channel or a multi-channel, but in the case of a cylindrical outer surface system, a multi-channel is preferably used.
In the present invention, the lithographic printing plate precursor subjected to the exposure treatment as described above may be subjected to a heat treatment and a water washing treatment.

(developing)
In the development processing in the present invention, a non-image portion of the photosensitive layer is removed using a developer.
In the present invention, the processing speed in the development processing, that is, the transport speed (line speed) of the lithographic printing plate precursor in the development processing is preferably 1.25 m / min or more, more preferably 1.35 m / min. More than a minute. Moreover, there is no restriction | limiting in particular in the upper limit of a conveyance speed, However, From a viewpoint of stability of conveyance, it is preferable that it is 3 m / min or less.
Hereinafter, the developer used in the present invention will be described.

-Developer-
The developer used in the present invention is preferably an alkaline aqueous solution having a pH of 14 or less, and preferably contains an aromatic anionic surfactant.
The developer according to the present invention preferably contains a chelating agent for a divalent metal, for example, for the purpose of suppressing the influence of calcium ions contained in hard water.

  Examples of the alkaline agent used in the developer according to the present invention include tribasic sodium phosphate, potassium, ammonium, sodium borate, potassium, ammonium, sodium hydroxide, potassium, ammonium, and lithium. Inorganic alkali agents such as monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine And organic alkali agents such as diisotopanolamine, ethyleneimine, ethylenediamine, pyridine, and tetramethylammonium hydroxide. In the present invention, these may be used alone or in combination of two or more.

  Moreover, alkali silicate can be mentioned as alkali agents other than the above. Alkali silicates may be used in combination with a base. The alkali silicate to be used exhibits alkalinity when dissolved in water, and examples thereof include sodium silicate, potassium silicate, lithium silicate, and ammonium silicate. These alkali silicates may be used alone or in combination of two or more.

The developer used in the present invention is composed of silicon oxide SiO ₂ which is a silicate component as a hydrophilizing component of a support and alkali oxide M ₂ O as an alkali component (M represents an alkali metal or ammonium group). By adjusting the mixing ratio and concentration, it can be easily adjusted to the optimum range. The mixing ratio of the silicon oxide SiO ₂ and the alkali oxide M ₂ O (the molar ratio of SiO ₂ / M ₂ O) is the amount of unclean stains caused by excessive dissolution (etching) of the anodic oxide film of the support. From the viewpoint of suppressing the generation of insoluble gas resulting from complex formation between dissolved aluminum and silicate, the range is preferably 0.75 to 4.0, more preferably 0.75 to 3.5. Used in.

In addition, the alkali silicate concentration in the developer includes the effect of inhibiting dissolution (etching) of the anodic oxide film on the support, the developability, the effect of inhibiting precipitation and crystal formation, and the gelation during neutralization during waste From the viewpoint of the prevention effect and the like, the SiO ₂ amount is preferably 0.01 to 1 mol / L, more preferably 0.05 to 0.8 mol / L with respect to the mass of the developer.

  The developer can be used as a developer and a development replenisher for the exposed lithographic printing plate precursor, and is preferably applied to an automatic processor. When developing using an automatic developing machine, the developing solution becomes fatigued according to the amount of processing, so that the processing capability may be restored by using a replenishing solution or a fresh developing solution. This replenishment method is also preferably applied to the plate making method of the present invention.

  Furthermore, in order to restore the processing capacity of the developer using an automatic developing machine, it is preferable to replenish by the method described in US Pat. No. 4,882,246. Developers described in JP-A-50-26601, 58-54341, JP-B-56-39464, 56-42860, and 57-7427 are also preferable.

  The lithographic printing plate thus developed is washed with water or a surfactant as described in JP-A Nos. 54-8002, 55-1115045, 59-58431, and the like. And the like, and a post-treatment with a desensitizing solution containing gum arabic, starch derivatives and the like. These processes may be performed in various combinations.

Furthermore, the lithographic printing plate after development can be subjected to full post-heating or full exposure on the developed image for the purpose of improving image strength and printing durability.
The planographic printing plate obtained by the above processing is loaded on an offset printing machine and used for printing a large number of sheets.
As plate cleaners used for removing stains on the plate during printing, conventionally known plate cleaners for PS plates are used, for example, multi cleaner, CL-1, CL-2, CP, CN-4. CN, CG-1, PC-1, SR, IC (manufactured by FUJIFILM Corporation), and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated according to an Example, the scope of the present invention is not limited to these Examples.

[Example 1]
(Production of support)
The surface treatment shown below was performed using a JIS A 1050 aluminum plate having a thickness of 0.30 mm and a width of 1030 mm.
In the surface treatment, the following various treatments (a) to (f) were continuously performed. In addition, after each process and water washing, the liquid was drained with the nip roller.

(A) The aluminum plate was etched at a caustic soda concentration of 26 mass%, an aluminum ion concentration of 6.5 mass%, and a temperature of 70 ° C. to dissolve the aluminum plate by 5 g / m ² . Thereafter, it was washed with water.
(B) A desmut treatment by spraying was performed with a 1% by mass aqueous solution of nitric acid having a temperature of 30 ° C. (including 0.5% by mass of aluminum ions), and then washed with water.
(C) An electrochemical surface roughening treatment was continuously performed using an alternating voltage of 60 Hz. The electrolytic solution at this time was a 1% by mass aqueous nitric acid solution (including 0.5% by mass aluminum ions and 0.007% by mass ammonium ions) at a temperature of 30 ° C. The AC power source was subjected to an electrochemical surface roughening treatment using a carbon electrode as a counter electrode using a trapezoidal rectangular wave alternating current with a time TP of 2 msec until the current value reached a peak from zero and a duty ratio of 1: 1. Ferrite was used for the auxiliary anode. The current density was 25 A / dm ² at the current peak value, and the amount of electricity was 250 C / cm ² in terms of the total amount of electricity when the aluminum plate was the anode. 5% of the current flowing from the power source was shunted to the auxiliary anode. Thereafter, it was washed with water.

(D) The aluminum plate was etched by spraying at 35 ° C. with a caustic soda concentration of 26% by mass and an aluminum ion concentration of 6.5% by mass, the aluminum plate was dissolved at 0.2 g / m ² , and electricity was obtained using the previous AC. The removal of the smut component mainly composed of aluminum hydroxide generated during chemical roughening and the edge portion of the generated pit were dissolved to smooth the edge portion. Thereafter, it was washed with water. (E) A desmut treatment by spraying was performed with a 25% by weight aqueous solution of sulfuric acid having a temperature of 60 ° C. (containing 0.5% by weight of aluminum ions), followed by washing with water by spraying.
(F) Anodization was performed for 50 seconds at a sulfuric acid concentration of 170 g / liter (containing 0.5 mass% of aluminum ions), a temperature of 33 ° C., and a current density of 5 (A / dm ² ). Thereafter, it was washed with water. At this time, the weight of the anodized film was 2.7 g / m ² .

  The surface roughness Ra of the aluminum support thus obtained was 0.27 (measuring instrument: Surfcom manufactured by Tokyo Seimitsu Co., Ltd., stylus tip diameter 2 micrometer).

(Formation of back coat layer)
Next, the following backcoat layer forming coating solution [BC-1] was prepared and applied to the aluminum support using a wire bar. Drying was performed at 100 ° C. for 70 seconds with a hot air drying apparatus to obtain a support on which a backcoat layer was formed. The total coating amount of this back coat layer (the coating amount after drying) was 0.46 g / m ² .

<Backcoat layer forming coating solution [BC-1]>
・ JER1009 (the following structure: Japan Epoxy Resin Co., Ltd.) 1.00 g
・ Fluorine surfactant 0.005g
(Megafuck F-780-F, Dainippon Ink and Chemicals,
Methyl isobutyl ketone (MIBK) 30% by mass solution)
・ Methyl ethyl ketone 22.5g
・ 2.5 g of 1-methoxy-2-propanol

(Formation of undercoat layer)
Subsequently, the following undercoat layer-forming coating solution was applied with a wire bar to the surface of the aluminum support opposite to the surface on which the backcoat layer was formed, and dried at 90 ° C. for 30 seconds. The coating amount was 10 mg / m ² .

<Coating liquid for undercoat layer formation>
-Polymer compound A having the following structure (weight average molecular weight: 10,000) 0.05 g
・ Methanol 27g
・ Ion exchange water 3g

(Formation of photosensitive layer)
The following photosensitive layer forming coating solution [P-1] was prepared and applied onto the undercoat layer formed as described above using a wire bar. Drying was performed at 125 ° C. for 34 seconds using a warm air dryer. The coating amount after drying was 1.4 g / m ² .

<Photosensitive layer forming coating solution [P-1]>
・ Infrared absorber (IR-1) 0.038 g
-Polymerization initiator A (S-1) 0.061g
-Polymerization initiator B (I-1) 0.094g
・ Mercapto compound (E-1) 0.015 g
・ Polymerizable compound (M-1) 0.425 g
(Product name: A-BPE-4 Shin-Nakamura Chemical Co., Ltd.)
-Binder polymer A (B-1) 0.311g
・ Binder polymer B (B-2) 0.250 g
-Binder polymer C (B-3) 0.062g
・ Additive (T-1) 0.079g
-Polymerization inhibitor (Q-1) 0.0012g
・ Ethyl violet (EV-1) 0.021g
・ Fluorine surfactant 0.0081g
(Megafuck F-780-F Dainippon Ink and Chemicals,
Methyl isobutyl ketone (MIBK) 30% by mass solution)
・ Methyl ethyl ketone 5.886g
・ Methanol 2.733g
・ 1-methoxy-2-propanol 5.886 g

  In addition, the infrared absorber (IR-1), the polymerization initiator A (S-1), the polymerization initiator B (I-1), the mercapto compound (E-1), which were used for the photosensitive layer forming coating solution, Polymerizable compound (M-1), binder polymer A (B-1), binder polymer B (B-2), binder polymer C (B-3), additive (T-1), polymerization inhibitor (Q- The structures of 1) and ethyl violet (EV-1) are shown below.

(Formation of lower protective layer)
On the formed photosensitive layer, synthetic mica (Somasif MEB-3L, 3.2% aqueous dispersion, manufactured by Coop Chemical Co., Ltd.), polyvinyl alcohol (Goselan CKS-50: saponification degree 99 mol%, polymerization degree 300) , Sulfonic acid-modified polyvinyl alcohol, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), surfactant A (manufactured by Nippon Emulsion Co., Ltd., Emalex 710), and surfactant B (Adeka Pluronic P-84: manufactured by Asahi Denka Kogyo Co., Ltd.) ) Was applied with a wire bar and dried at 125 ° C. for 30 seconds with a hot air dryer.
The content ratio of synthetic mica (solid content) / polyvinyl alcohol / surfactant A / surfactant B in the mixed aqueous solution (coating liquid for protective layer) was 7.5 / 89/2 / 1.5 (mass). The coating amount (the coating amount after drying) was 0.5 g / m ² .

(Formation of upper protective layer)
On the lower protective layer, an organic filler (Art Pearl J-7P, manufactured by Negami Industrial Co., Ltd.), synthetic mica (Somasif MEB-3L, 3.2% aqueous dispersion, manufactured by Coop Chemical Co., Ltd.), polyvinyl alcohol ( L-3266: degree of saponification 87 mol%, degree of polymerization 300, sulfonic acid-modified polyvinyl alcohol Nippon Synthetic Chemical Industry Co., Ltd.), thickener (Serogen FS-B, Daiichi Kogyo Seiyaku Co., Ltd.), high A mixed aqueous solution (a coating solution for forming an upper protective layer) of molecular compound A (the above structure) and a surfactant (manufactured by Nippon Emulsion Co., Ltd., Emalex 710) is applied with a wire bar, and 125 ° C. using a hot air dryer. For 30 seconds.
The content ratio of the organic filler / synthetic mica (solid content) / polyvinyl alcohol / thickener / polymer compound A / surfactant in the mixed aqueous solution (upper protective layer forming coating solution) is 4.7 / 2. The ratio was 0.8 / 67.4 / 18.6 / 2.3 / 4.2 (mass%), and the coating amount (the coating amount after drying) was 1.2 g / m ² .
Thereby, a photosensitive lithographic printing plate precursor used in Example 1 was obtained.

〔exposure〕
The obtained photosensitive lithographic printing plate precursor (650 mm × 550 mm × 0.3 mm thickness) is conveyed to a Trend setter 3244 manufactured by Creo, and a standard image pattern shown in FIG. 1A is output at 7 W and an external drum rotational speed of 150 rpm. And exposure with a plate surface energy of 110 mJ / cm ² .
The standard image pattern was exposed to a size of 20 mm in length and 250 mm in width in the periphery of the practical image of the photosensitive lithographic printing plate precursor, that is, the portion to be discarded after being printed.

(Standard image pattern)
The standard image pattern used in the developer evaluation method for the lithographic printing plate of Example 1 is as follows.
As shown in FIG. 1A, the AM halftone dot image formation region was a rectangle, and the FM halftone dot image formation region was a circle composed of circular dots having a diameter of 10 μm. The AM halftone dot image in the surrounding rectangular area is an AM screen type 175 line / inch (2.5 cm) halftone dot image having a digital area ratio of 30% to 60% in increments of 1%. 0 to No. What changed the area ratio in 31 31 steps of 30 was produced.
Such a standard image pattern was exposed to an area to be cut and removed after image formation at the periphery of the photosensitive lithographic printing plate precursor to be evaluated.
The developed standard image pattern is visually observed, and an area where the density of the FM halftone dot image in the center and the AM halftone dot image in the peripheral part appear to be the same is detected. Was evaluated.

〔developing〕
After the exposure as described above, the heat treatment and the water washing treatment are not performed, and development is performed at a conveyance speed (line speed) of 2 m / min and a development temperature of 30 ° C. using an automatic developing machine LP-1310NewsII manufactured by Fujifilm Corporation. Processed. The developer used was a 1: 4 water diluted solution of DH-N, the developer replenisher was diluted 1: 1.4 water of FCT-421, and the finisher was 1: 1 of GN-2K manufactured by FUJIFILM Corporation. A water dilution was used. The development time was 12 seconds (initial setting value).

  The adjustment of the exposure / development conditions in this example is 2 points or more when comparing “No.” in which the density appears to be the same in the target development processing plate and “No.” in which the density appears to be the same in the standard plate. When it deviates, that is, when the dot area ratio deviates by 2%, the exposure amount is changed.

The exposure / development processing was carried out continuously for 60 days for 60 plates per day.
During the implementation period, the developer is evaluated every day using the lithographic printing plate developer evaluation method of the present invention, and the obtained evaluation results are fed back to the exposure process to adjust the exposure conditions for quality control. Went.

As the standard plate, a plate made on the first day of the test period was used.
No. of this standard version. 19, the halftone dot area ratio of the digital 30% FM screen system having a diameter of 10 μm was 47% on the plate, and the halftone dot area ratio of the 175 line / inch digital 49% AM screen system was 47% on the plate. The same concentration was visually observed. Therefore, the comparison point of this standard version is No. 19, and the control strip display of this standard version was “No. 19”.
In addition, as the target developer evaluation plate, a plate which was first made under the same conditions as the standard plate every day during the test period was used.
The halftone dot% was measured using a reflection densitometer (D19C type) manufactured by GRETAG.

Details of quality control in the first embodiment are as follows.
On the 19th day, the target developer evaluation version No. 17, the halftone dot area ratio of the digital 30% FM screen system having a diameter of 10 μm was 45% on the plate, and the halftone dot area ratio of the 175 line / inch digital 46% AM screen system was 45% on the plate. The same concentration was visually observed. Therefore, the control strip display of the target developer evaluation plate on the 19th day is “No. 17”.
Thus, there was a difference of 2 points between the reference plate “No. 19” and the target developer evaluation plate “No. 17”, and the halftone dot area ratio was also 2%. Based on the quality control method of the invention, the evaluation results were fed back, and the exposure amount was changed to 120 mJ / cm ² .
When plate making was performed with the changed exposure amount, the same dot area ratio and density were obtained with “No. 19” as in the standard version, and the control strip display of this plate was “No. 19”.

On the 43rd day, the target developer evaluation version No. 21, the dot area ratio of the digital 30% FM screen method with a diameter of 10 μm was 49% on the plate, and the dot area ratio of the 175 line / inch digital 51% AM screen method was 49% on the plate. The same concentration was visually observed. Therefore, the control strip display of the target developer evaluation plate on the 43rd day is “No. 21”.
Thus, there was a difference of 2 points between the reference plate “No. 19” and the target developer evaluation plate “No. 21”, and the halftone dot area ratio was also 2%. Based on the quality control method of the invention, the evaluation result was fed back and the exposure amount was changed to 100 mJ / cm ² .
When plate making was performed with the changed exposure amount, the same dot area ratio and density were obtained with “No. 19” as in the standard version, and the control strip display of this plate was “No. 19”.

From the above results, if the developer evaluation method of the present invention and the quality control method of the present invention using the developer evaluation method are not used, the automatic developing machine is in a condition that a lithographic printing plate in a preferable state can be obtained, That means it could only be operated for 18 days.
This shows that the developer evaluation method of the present invention and the quality control method of the present invention using the developer evaluation method are effective.

[Example 2]
A photosensitive lithographic printing plate precursor produced in the same manner as in Example 1 was exposed and developed in the same manner as in Example 1.
The exposure / development process was carried out continuously for 40 days for 40 plates per day.
During the implementation period, the developer is evaluated every day using the lithographic printing plate developer evaluation method of the present invention, and the obtained evaluation results are fed back to the exposure process to adjust the exposure conditions for quality control. Went.

As the standard plate, a plate made on the first day of the test period was used.
No. of this standard version. 19, the halftone dot area ratio of the digital 30% FM screen system having a diameter of 10 μm was 47% on the plate, and the halftone dot area ratio of the 175 line / inch digital 49% AM screen system was 47% on the plate. The same concentration was visually observed. Therefore, the comparison point of this standard version is No. 19, and the control strip display of this standard version was “No. 19”.
In addition, as the target developer evaluation plate, a plate which was first made under the same conditions as the standard plate every day during the test period was used.
The halftone dot% was measured using a reflection densitometer (D19C type) manufactured by GRETAG.

Details of quality control in the second embodiment are as follows.
On the 24th day, the target developer evaluation version No. 21, the dot area ratio of the digital 30% FM screen method with a diameter of 10 μm was 49% on the plate, and the dot area ratio of the 175 line / inch digital 51% AM screen method was 49% on the plate. The same concentration was visually observed. Therefore, the control strip display of the target developer evaluation plate on the 24th day is “No. 21”.
Thus, there was a difference of 2 points between the reference plate “No. 19” and the target developer evaluation plate “No. 21”, and the halftone dot area ratio was also 2%. Based on the quality control method of the invention, the evaluation results were fed back, and the development time was changed from 12 seconds (initial setting value) to 14 seconds.
When plate making was performed with the changed exposure amount, the same dot area ratio and density were obtained with “No. 19” as in the standard version, and the control strip display of this plate was “No. 19”.

On the 46th day, the target developer evaluation version No. 17, the halftone dot area ratio of the digital 30% FM screen system having a diameter of 10 μm was 45% on the plate, and the halftone dot area ratio of the 175 line / inch digital 47% AM screen system was 45% on the plate. The same concentration was visually observed. Therefore, the control strip display of the target developer evaluation plate on the 46th day is “No. 17”.
Thus, there was a difference of 2 points between the reference plate “No. 19” and the target developer evaluation plate “No. 17”, and the halftone dot area ratio was also 2%. Based on the quality control method of the invention, the evaluation results were fed back, and the development temperature was changed from 30 ° C. (initial setting value) to 28 ° C.
When plate making was performed with the changed exposure amount, the same dot area ratio and density were obtained with “No. 19” as in the standard version, and the control strip display of this plate was “No. 19”.

From the above results, if the developer evaluation method of the present invention and the quality control method of the present invention using the developer evaluation method are not used, the automatic developing machine is in a condition that a lithographic printing plate in a preferable state can be obtained, That means it could only be operated for 23 days.
This shows that the developer evaluation method of the present invention and the quality control method of the present invention using the developer evaluation method are effective.

(A)-(C) are model diagrams showing an AM dot image formation region and an FM dot image formation region formed adjacent to each other in the standard image pattern of the present invention.

Explanation of symbols

10 Standard image pattern 12 AM halftone dot image formation region 14 FM halftone image formation region

Claims (4)

Developers used for an infrared photosensitive lithographic printing plate precursor having a photosensitive layer containing an infrared absorber, a polymerizable compound, and a polymerization initiator are the following (A), (B), (C), and (D ) A lithographic printing plate developer evaluation method characterized by evaluating by a step.
(A) A predetermined area ratio using a plurality of AM halftone images having different area ratios by the AM screen method and circular dots having a diameter of 10 μm to 75 μm adjacent to each of the plurality of AM halftone images. An infrared-exposed plate obtained in steps (B) and (A) of exposing an infrared-sensitive lithographic printing plate precursor to a standard image pattern comprising an FM halftone image using an FM screen system having Step (C) for developing a standard plate by developing in (A) A step (D) for developing an infrared-exposed plate according to (A), which is different from (B), and preparing a target developer evaluation plate (D) ) A step of comparing halftone dot area ratios of the standard plate and the target development evaluation plate   The AM halftone image is a halftone dot image having a screen line number of 80 lines / inch to 300 lines / inch, and the FM halftone image has an area ratio of 30% to 70%. The lithographic printing plate developer evaluation method according to claim 1, wherein: When making an infrared-sensitive lithographic printing plate precursor having a photosensitive layer containing an infrared absorber, a polymerizable compound, and a polymerization initiator, the following (A), (B), (C), (D), and (E) A quality control method for a lithographic printing plate, which is controlled by a process.
(A) A predetermined area ratio using a plurality of AM halftone images having different area ratios by the AM screen method and circular dots having a diameter of 10 μm to 75 μm adjacent to each of the plurality of AM halftone images. An infrared-exposed plate obtained in steps (B) and (A) of exposing an infrared-sensitive lithographic printing plate precursor to a standard image pattern comprising an FM halftone image using an FM screen system having Step (C) for developing a standard plate by developing in (A) A step (D) for developing an infrared-exposed plate according to (A), which is different from (B), and preparing a target developer evaluation plate (D) ) Steps (E) and (D) of comparing the halftone dot area ratios of the standard plate and the target development evaluation plate. Is greater than or equal to Adjusting exposure conditions and / or development conditions (F) It further includes a step of replacing the plate subjected to exposure and development under the conditions adjusted in the step (E) with the target developer evaluation plate in the step (C),
The lithographic printing plate quality control method according to claim 3, wherein the steps (F), (D), and (E) are repeated one or more times in this order.

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