JP2001013692A - Method for evaluating image and method for controlling quality of planographic printing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple evaluating method by which the state of a positive type image forming material for IR laser to be subjected to a direct photomechanical process under the conditions of the process is easily judged and to provide a quality control method for keeping the quality of a planographic printing plate uniform by feeding back the evaluated result to exposing and developing steps. SOLUTION: A positive type image forming material for IR laser is exposed under plural conditions while stepwise varying energy to produce a planographic printing plate for evaluation and this planographic printing plate is developed with a standard developing solution having a standard blend to produce a planographic printing plate processed with the standard developing solution. The planographic printing plate for evaluation is developed with a developing solution to be evaluated to produce a planographic printing plate processed with the target developing solution. The states of the image or non-image areas of the planographic printing plate processed with the standard developing solution and the planographic printing plate processed with the target developing solution under prescribed exposure conditions are compared.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating an image of a positive type image forming material for a so-called direct plate making infrared laser, which can be used as an offset printing master and can be made directly from a digital signal from a computer or the like. It relates to the quality control method of lithographic printing plates.

[0002]

2. Description of the Related Art In recent years, the development of lasers has been remarkable, and in particular, solid lasers and semiconductor lasers having a light emitting region in the near infrared to infrared region have been increasing in output and miniaturization. Therefore, these lasers are very useful as an exposure light source when making a plate directly from digital data of a computer or the like. The above-described positive lithographic printing plate material for an infrared laser using an infrared laser having a light emitting region in the infrared region as an exposure light source is composed of a binder resin soluble in an aqueous alkali solution and an I.sub.2 which absorbs light and generates heat.
A lithographic printing plate material containing an R dye or the like as an essential component.

When the above-mentioned infrared laser is exposed to the positive lithographic printing plate material for an infrared laser, an IR dye or the like in the positive lithographic printing plate material for an infrared laser is converted into a binder in a non-exposed area (image area). The interaction with the resin acts as a dissolution inhibitor that substantially reduces the solubility of the binder resin. On the other hand, in the exposure part (non-image part),
Since the IR dye or the like absorbs light and generates heat, the interaction between the IR dye or the like and the binder resin is weakened. Therefore, at the time of development, the exposed portion (non-image portion)
Are dissolved in an alkaline developer to form a lithographic printing plate. However, in such a positive type lithographic printing plate material for an infrared laser, the latitude with respect to the activity of the developer is narrower than that of the positive type lithographic printing plate material made by UV exposure. When the activity is increased, the density and the printing durability are lowered, and there is a problem that poor development is easily caused. The problem is caused by the following essential difference in the plate making mechanism between the positive lithographic printing plate material for infrared laser and the positive lithographic printing plate material made by UV exposure.

The positive type lithographic printing plate material to be made by UV exposure contains a binder resin soluble in an aqueous alkali solution and onium salts and quinonediazide compounds as essential components. Here, when the positive type lithographic printing plate material to be made by the UV exposure is exposed, the onium salt and the quinonediazide compound are exposed in the non-exposed area (image area) in the positive type lithographic printing plate material for infrared laser. Acts as a dissolution inhibitor in the same way as described above, but in exposed areas (non-image areas)
In the above, unlike the positive type lithographic printing plate material for an infrared laser, it is decomposed by light to generate an acid and acts as a dissolution accelerator for the binder resin.
Therefore, in the positive lithographic printing plate material produced by the UV exposure, the difference in solubility between the exposed part and the non-exposed part in an alkali developing solution is very large.

On the other hand, in the positive lithographic printing plate material for infrared laser, the interaction between the IR dye or the like and the binder resin is weakened in the exposed portion (non-image portion) during exposure, but the IR dye However, since it does not act as a dissolution accelerator for the binder, the difference in solubility between the unexposed portion and the exposed portion is small. In order to continuously form a stable image using an image forming material having a small latitude with respect to the activity of the developer, it is very difficult to control the process. Usually, when developing a positive photosensitive lithographic printing plate for infrared laser, an automatic developing machine having a replenishing mechanism for keeping the developer sensitivity as constant as possible is used. The replenishing mechanism adds a highly active replenisher in order to prevent the pH of the developer from lowering due to the development processing of the plate or the absorption of CO ₂ , thereby preventing the developing property from lowering. Specifically, the normal P
In the S-plate processing system, the conductivity is managed and a method of adding a replenisher so that it becomes constant, or every time the number of plate development processing reaches a certain number, or after a certain processing time, For example, a method of periodically adding a predetermined amount of replenisher has been proposed. However, in the method of controlling by the electric conductivity, when the number of development processes is increased and the composition of the photosensitive layer is dissolved in a large amount, the pH is different even at the same electric conductivity value from the start, and the developability is also different. There is a fact.

In the method of adding a predetermined amount of replenisher at a predetermined interval, such as the number of developed lithographic printing plates or a predetermined time, the amount of replenishment per unit area of the plate is limited. Depending on factors such as the amount of the photosensitive layer composition that dissolves into the developer depending on the developer, and the amount of CO ₂ absorbed over time depending on the installation environment (temperature, humidity, CO ₂ concentration, etc.) of the automatic developing machine, the conditions are delicate. It is difficult to continuously maintain uniform developability by changing and maintaining the value at a constant value.

[0007] The above point does not cause a serious problem because a normal lithographic printing plate using UV exposure has a wide latitude, but a positive photosensitive lithographic printing plate for an infrared laser has a narrow latitude as described above. A change in the activity of the developer greatly changes the image formability, and thus easily causes a quality problem of the lithographic printing plate. However, there is still found a method of applying the method to a general-purpose infrared laser positive lithographic printing plate material and effectively preventing a decrease in image density, a decrease in printing durability, or a poor development by a simple process control. There is no present.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and achieve the following objects. That is, the present invention provides a simple evaluation method for easily determining the plate making conditions of a positive type image forming material for an infrared laser for direct plate making, particularly, an active state of a developer, and exposing the result to exposure /
It is an object of the present invention to provide a quality control method for feeding back to a developing step to maintain the quality of a lithographic printing plate constant and continuously form a uniform image.

[0009]

As a result of the study, the present inventors have made a plate of an image forming material which has been subjected to a specific standard exposure, and then made a plate of an image forming material to be evaluated. By comparing, it was found that the quality of the lithographic printing plate can be easily controlled by feeding back the evaluation method by simply evaluating the formed image, and by feeding back the evaluation method, and completed the present invention. .

That is, the image evaluation method of the present invention comprises: (A) an image-forming material having a photosensitive layer on a support, which contains a resin soluble in an aqueous alkali solution and a compound that absorbs light and generates heat. Steps in which a lithographic printing plate for evaluation is prepared by performing exposure under a plurality of conditions while gradually changing the plate surface energy, and developing with a standard developing solution having a standard formulation to prepare a standard developing solution-processed lithographic printing plate. (B) developing a lithographic printing plate for evaluation, which has been exposed under the same conditions as described above, with a developing solution to be evaluated to prepare a lithographic printing plate treated with a target developing solution;
(C) comparing the state of the image area or the non-image area of the standard developed lithographic printing plate and the target developed lithographic printing plate under predetermined exposure conditions.

The quality control method of a lithographic printing plate according to the present invention according to claim 2 comprises: (A) a support containing a resin soluble in an aqueous alkali solution and a compound capable of absorbing light to generate heat. A lithographic printing plate for evaluation, which is obtained by exposing the image forming material having a photosensitive layer to a plurality of conditions while changing the plate surface energy in a stepwise manner, is developed with a standard developing solution having a standard formulation, and treated with a standard developing solution. A step of preparing a lithographic printing plate and (B) the same as the standard development lithographic printing plate, except that the evaluation lithographic printing plate exposed under the same conditions as described above is developed with a developer to be evaluated. (C) comparing the state of the image area or the non-image area of the standard developed lithographic printing plate and the target developed lithographic printing plate under predetermined exposure conditions (D) the image portion or the non- As a result of comparing an image portion, when both the difference exceeds a predetermined value, characterized in that it and a step of adjusting the exposure / development conditions.

Here, the difference in plate energy between adjacent exposed portions in the step of preparing an evaluation lithographic printing plate by performing exposure under a plurality of conditions while changing the plate surface energy stepwise is 3 to 50%. Is preferred. (C) When comparing the state of the image area or the non-image area under the predetermined exposure condition between the standard developed lithographic printing plate and the target developed lithographic printing plate, the plate surface energy in the exposure is changed stepwise, Developed, the plate energy at the minimum exposure amount where the exposed portion was completely dissolved, that is, clear sensitivity, or the plate surface energy at the maximum exposure amount at which the density does not change from the unexposed portion, that is, comparing the solid sensitivity, was evaluated. This is a preferred mode for ensuring that there is no variation.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. In the present invention, first, a lithographic printing plate for evaluation that has been subjected to stepwise exposure (hereinafter, appropriately referred to as an original plate for evaluation) is prepared. This has the same function as the gray scale used for the general UV exposure type PS plate,
On an image forming material having a photosensitive layer containing a resin soluble in an aqueous alkaline solution and a compound that absorbs light and generates heat, a light-exposed portion at each stage is, for example, a laser beam. Is created step by step by changing the output of At this time, the difference in plate energy between adjacent exposed portions is 3
It is preferably from 50 to 50%, and in the case of more precise management, it is more preferably from 3 to 20%, and most preferably from 5 to 10%. Considering that the difference in plate energy between adjacent exposed portions in a normal gray scale is about 40%, it is preferable to perform more precise management in the infrared exposure type lithographic printing plate according to the present invention. I understand.

Such an original plate for evaluation is prepared independently, and is applied at a predetermined interval between planographic printing plates to be made in a general developing and plate making apparatus. Although it may be used to confirm the plate making conditions, the margin of the planographic printing plate, which is the product to be made, i.e., the evaluation for performing such stepwise exposure on the frame portion of the planographic printing plate, etc. Evaluation and quality control can also be performed by creating an exposure unit and confirming the plate making status.

The evaluation master thus prepared is first developed with (A) a standard developer having a standard composition to prepare a lithographic printing plate treated with a standard developer. This is a standard sample of the development conditions serving as a base, and the formulation, processing time, processing temperature, and the like of the developer used here are adopted as standard processes. It is not necessary to prepare a standard developer-processed lithographic printing plate as an evaluation criterion for each evaluation. If evaluation and management are to be performed in a continuous process of performing the same plate-making process, one step is required at the first stage. You only need to make one.

Next, a planographic printing plate to be evaluated is created. This is for confirming the state of fatigue of the developer after lapse of time, and the above-mentioned evaluation original plate is processed at the time when evaluation is required. This is the same as the standard development lithographic printing plate except that (B) the lithographic printing plate for evaluation, which has been exposed under the same conditions as described above, is developed with the developing solution to be evaluated. This is the step of creating a processed planographic printing plate. At this time, the development processing temperature, processing time, and the like are set to the same conditions as when the standard developer-processed lithographic printing plate was prepared.

Next, the lithographic printing plate as a standard for evaluation and the lithographic printing plate to be obtained obtained as described above,
(C) The evaluation is performed by comparing the developed state of the image portion or the non-image portion of the portion under the same exposure condition. Since the evaluation is a pairwise comparison, the state of the plate surface may be evaluated visually, or printing may be performed using the obtained lithographic printing plate to compare the printing stain resistance and printing durability. Preferably, from the viewpoint of simplicity, the comparison is performed visually or by concentration. At this time,
In the evaluation original plate that was exposed and developed by changing the plate energy in the exposure stepwise, the plate energy at the minimum exposure amount where the exposed portion was completely dissolved (hereinafter, referred to as
In the present invention, the clear surface sensitivity (hereinafter referred to as "solid sensitivity") or the plate surface energy at the maximum exposure amount at which the density does not change from the unexposed portion (hereinafter referred to as "solid sensitivity" in the present invention) is obtained. Comparing the solid sensitivity and / or the solid sensitivity is a preferable embodiment for ensuring that the evaluation does not vary. At this time, both the clear sensitivity and the solid sensitivity may be compared, or only one of them may be compared.

As described above, changes in exposure / development conditions can be easily detected by comparison with a sample which has been subjected to standard development processing. Therefore, the evaluation results of this lithographic printing plate
The quality control of the lithographic printing plate can be rationally performed by feeding back to the exposure process, development, and plate making process. That is, if a decrease in developability is observed in the tested lithographic printing plate, increase the exposure conditions,
Means for activating the developing conditions may be employed. If the image is excessively developed, the exposure conditions may be reduced or the developing conditions may be relaxed. The limit when this evaluation result is fed back to the exposure / development step may be determined depending on the desired uniformity of the lithographic printing plate. In general, both the clear sensitivity and the solid sensitivity deviate from the standard sample by 20%. In other words, when (data of the target developed lithographic printing plate) / (data of the standard developed lithographic printing plate) is out of the range of 0.8 to 1.2, the standard for feedback to the exposure / developing process is Become.

To adjust the exposure step, the output of the laser beam, the beam diameter, the scanning speed, the exposure time, and the like may be adjusted and adjusted to the desired exposure conditions.

As a countermeasure method when the sensitivity is out of the specified range, when the development is excessively performed, the following steps can be taken. In the development step, (1) water is added to the developer, (2) Put dry ice into the developer (3) Inject CO ₂ gas (4) Decrease the dilution ratio of the replenisher (5) Decrease the setting of the replenishment amount of the automatic processor (6) Decrease the development temperature ( 7) Shorten the developing time (increase the transport speed of the automatic developing machine) (8) Reduce the pressure of the developing brush of the automatic developing machine (9) Reduce the number of developing brushes of the automatic developing machine (10) Spray amount (11) Stir the developer (12) Replace the developer with a new solution. In addition, as means to be applied to the exposure step and other steps, (13) the amount of exposure can be reduced, and (14) the positive photosensitive lithographic printing plate for infrared laser can be heated before exposure.

On the other hand, as a countermeasure method when the sensitivity is out of the specified range due to a decrease in developability, the following steps can be taken. In the development step, (1) a replenisher is added. Increase the dilution ratio. (3) Increase the replenishment amount setting of the automatic processor. (4) Increase the developing temperature. (5) Increase the developing time (reduce the transport speed of the automatic processor). (7) Increase the number of developing brushes of the automatic developing machine (8) Increase the spray discharge amount (9) Change the developing solution to a new solution. As a means applied to the exposure step and other steps, there is a method (10) of increasing the exposure amount.

Next, the image forming material to which the method of the present invention is applied will be described. The image forming material according to the present invention,
There is no particular limitation as long as a photosensitive layer made of a positive photosensitive composition for an infrared laser is provided on a support. The photosensitive layer is made of (a) an aqueous alkali solution-soluble resin and (b) light. It contains a compound that generates heat upon absorption, and as a positive photosensitive composition for infrared laser,
It may be one to which additives or the like generally used are added.

Examples of the (a) alkali aqueous solution-soluble resin used in the present invention include a novolak resin and a polymer having a hydroxyaryl group in a side chain. The novolak resin that can be used as the alkali aqueous solution-soluble resin of the present invention is a resin obtained by condensing phenols and aldehydes under acidic conditions. Preferred novolak resins include, for example, a novolak resin obtained from phenol and formaldehyde, a novolak resin obtained from m-cresol and formaldehyde, a novolak resin obtained from p-cresol and formaldehyde, o-
Novolak resin obtained from cresol and formaldehyde, novolak resin obtained from octylphenol and formaldehyde, novolak resin obtained from m- / p-mixed cresol and formaldehyde, phenol / cresol (m-, p-, o- or m- / p −, M
-/ O- or o- / p-) and a novolak resin obtained from formaldehyde. These novolak resins have a weight average molecular weight of 800 to 200,000 and a number average molecular weight of 400.
~ 60,000 are preferred. Further, as the alkali aqueous solution-soluble resin of the present invention, a polymer having a hydroxyaryl group in a side chain can also be preferably mentioned. In this polymer, a hydroxyaryl group refers to an aryl group in which one or more -OH groups are bonded. Examples of the aryl group include a phenyl group, a naphthyl group, an anthracenyl group, and a phenanthrenyl group. From the viewpoint of availability and physical properties, a phenyl group or a naphthyl group is preferable. Accordingly, the hydroxyaryl group is preferably a hydroxyphenyl group, a dihydroxyphenyl group, a trihydroxyphenyl group, a tetrahydroxyphenyl group, a hydroxynaphthyl group, a dihydroxynaphthyl group, or the like. These hydroxyaryl groups further include a halogen atom, a hydrocarbon group having 20 or less carbon atoms, an alkoxy group having 20 or less carbon atoms, and a
It may have 0 or less substituents such as an aryloxy group. These hydroxyaryl groups are pendantly bonded to the polymer main chain as side chains of the polymer, but may have a linking group with the main chain.

As the compound (b) which generates heat by absorbing light, various known pigments and dyes are preferably exemplified. Examples of the pigment include commercially available pigment and color index (CI) handbook, “Latest Pigment Handbook” (edited by Japan Pigment Technical Association, 1977), “Latest Pigment Application Technology”
(CMC Publishing, 1986), "Printing ink technology" C
MC Publishing, 1984).

Examples of the pigments include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and polymer-bound pigments. . Specifically, insoluble azo pigments, azo lake pigments, condensed azo pigments, chelated azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments And quinophthalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, inorganic pigments, carbon black and the like.

The pigment may be used without being subjected to a surface treatment, or may be used after being subjected to a surface treatment. Examples of the surface treatment include a method of surface-coating a resin or wax, a method of attaching a surfactant, and a method of bonding a reactive substance (for example, a silane coupling agent, an epoxy compound, or a polyisocyanate) to the pigment surface. Can be considered. The surface treatment method is described in “Properties and Applications of Metallic Soap” (Koshobo), “Printing Ink Technology” (CMC Publishing, 1984) and “Latest Pigment Application Technology” (CMC Publishing, 198).
6th edition).

The pigment has a particle size of 0.01 to 10
μm is preferable, and 0.05 to 1 μm is more preferable.
0.1-1 μm is particularly preferred. The particle size of the pigment,
If the thickness is less than 0.01 μm, the dispersion may not be preferable in terms of stability in the photosensitive layer coating solution.
If it exceeds μm, it is not preferable in terms of uniformity of the photosensitive layer.

As a method for dispersing the pigment, a known dispersion technique used in the production of ink or toner can be used. For the dispersion, an ultrasonic disperser, a sand mill, an attritor, a pearl mill, a super mill, a ball mill,
Impeller, desparser, KD mill, colloid mill,
A disperser such as a Dynatron, a three-roll mill, or a pressure kneader is used. For details, see “Latest Pigment Application Technology” (CM
C Publishing, 1986).

Examples of the dye include commercially available dyes and literatures (for example, "Dye Handbook" edited by The Society of Synthetic Organic Chemistry, Showa 45).
Known publications, for example, dyes such as azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinone imine dyes, methine dyes, and cyanine dyes. Can be Among the pigments and dyes, pigments and dyes that absorb infrared light or near infrared light are particularly preferable because they are suitable for use in lasers that emit infrared light or near infrared light.

As the pigment absorbing the infrared light or the near infrared light, carbon black is preferably used. Examples of the dye that absorbs infrared light or near infrared light include, for example, JP-A-58-125246 and JP-A-59-125246.
No. 84356, JP-A-59-202829, JP-A-Sho-6
0-78787, cyanine dyes described in JP-A-58-173696 and JP-A-58-181690.
Methine dyes described in JP-A-58-194595, JP-A-58-112793 and JP-A-58-112793.
No. 224793, JP-A-59-48187, JP-A-5-48187
Naphthoquinone dyes described in JP-A-9-73996, JP-A-60-52940 and JP-A-60-63744; squalilium dyes described in JP-A-58-112792; British Patent 434,875 And the like.

The dyes described in US Pat.
The near-infrared absorption sensitizers described in US Pat. No. 156,938 are also preferably used, and substituted arylbenzo (thio) pyrylium salts described in U.S. Pat. No. 3,881,924, JP-A-57-142645. (U.S. Pat. No. 4,327,169)
No. 3) described in JP-A-58-1983.
No. 181051, No. 58-220143, No. 59-4
Nos. 1363, 59-84248, 59-8424
No. 9, No. 59-146063, No. 59-146061
Pyrylium compounds described in JP-A-59-
No. 216146, US Pat.
Pentamethine thiopyrylium salt described in JP-A-83,475, pyrylium compounds disclosed in JP-B-5-13514 and JP-A-5-19702, and Epollight.
III-178, Epollight III-130, Epo
light III-125, Epollight V-176
A and the like are particularly preferably used.

Another particularly preferred example of the dye is a near-infrared absorbing dye described as formulas (I) and (II) in US Pat. No. 4,756,993. The amount of the pigment or dye added is preferably 0.01 to 50% by weight, more preferably 0.1 to 10% by weight, based on the total solid content of the printing plate material. In the case of the dye, 0.5 to 10% by weight is particularly preferable, and in the case of a pigment, 3.1 to 10% by weight is particularly preferable. When the amount of the pigment or dye is less than 0.01% by weight,
On the other hand, if the sensitivity is lowered, if it exceeds 50% by weight, the uniformity of the photosensitive layer may be lost and the durability of the recording layer may be deteriorated.

The dye or pigment may be added to the same layer as other components or may be added to another layer. When added to a layer separate from other components, it is added to a layer adjacent to a layer containing a substance which is thermally decomposable and substantially reduces the solubility of the binder resin when not decomposed. Is preferred. The dye or pigment and the binder resin are preferably contained in the same layer, but may be contained in different layers.

The photosensitive layer may contain other components, if desired. Other ingredients include
Various additives are mentioned, such additives include
For example, onium salts, o-quinonediazide compounds, aromatic sulfone compounds, aromatic sulfonic acid ester compounds and the like are substances that are thermally decomposable and substantially reduce the solubility of an alkali water-soluble polymer compound when not decomposed. Can be The addition of the above-mentioned additive can improve the dissolution inhibiting property of the image area in the developer.

As the onium salt, a diazonium salt,
Examples thereof include ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, arsonium salts and the like. Among these, diazonium salts are particularly preferred.
No. 30 is preferable.

The o-quinonediazide compound includes:
Compounds having various structures are preferred as long as they have at least one o-quinonediazide group and increase alkali solubility by thermal decomposition. Since the o-quinonediazide has both an effect of losing the ability to suppress the dissolution of the binder by thermal decomposition and an effect of changing o-quinonediazide itself to an alkali-soluble substance, the o-quinonediazide dissolves the binder. It can act as an accelerator.

The amount of the o-quinonediazide compound to be added is preferably 1 to 50% by weight, more preferably 5 to 30% by weight, more preferably 10 to 30% by weight, based on the total solid content of the printing plate material.
% By weight is particularly preferred.

Examples of the counter ion of the onium salt include tetrafluoroboric acid, hexafluorophosphoric acid, triisopropylnaphthalenesulfonic acid, 5-nitro-o-toluenesulfonic acid, 5-sulfosalicylic acid, 2,5-dimethyl Benzenesulfonic acid, 2,4,6-trimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 3-chlorobenzenesulfonic acid, 3-bromobenzenesulfonic acid, 2-fluorocaprylnaphthalenesulfonic acid, dodecylbenzenesulfonic acid, 1-naphthol -5-sulfonic acid, 2-
Methoxy-4-hydroxy-5-benzoyl-benzenesulfonic acid, p-toluenesulfonic acid and the like can be mentioned. Of these, particularly preferred are hexafluorophosphoric acid, alkylaromatic sulfonic acids such as triisopropylnaphthalenesulfonic acid and 2,5-dimethylbenzenesulfonic acid.

The amount of the additives other than the o-quinonediazide compound is preferably 1 to 50% by weight,
30% by weight is more preferable, and 10 to 30% by weight is particularly preferable. It is preferable that the additive and the binder are contained in the same layer.

For the purpose of further improving sensitivity, cyclic acid anhydrides such as phthalic anhydride, bisphenol A, p-
Phenols such as nitrophenol and organic acids such as p-toluenesulfonic acid and dodecylbenzenesulfonic acid can also be added. As the proportion of the cyclic acid anhydride, phenols or organic acids in the printing plate material,
0.05-20% by weight is preferred, and 0.1-15% by weight
Is more preferable, and 0.1 to 10% by weight is particularly preferable.

The photosensitive layer may contain a surfactant, for example, a fluorine-based surfactant described in JP-A-62-170950, in order to improve coatability. As the content of the surfactant, the content of the above-mentioned image recording material is set to 0.1.
It is preferably from 01 to 1% by weight, more preferably from 0.05 to 0.5% by weight.

The image-forming material of the present invention is formed by dissolving each of the above-mentioned components in a solvent, and coating the solution on a support described later.

-Support-The support is preferably a dimensionally stable plate, for example, paper, paper (eg, polyethylene, polypropylene, polystyrene, etc.) laminated thereon, metal plate (for example, , Aluminum, zinc, copper, etc.), plastic films (eg, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.) ), Paper as described above, or paper or plastic film on which metal is laminated or vapor-deposited.

As the support, a polyester film or an aluminum plate is preferable, and among them, an aluminum plate which has good dimensional stability and is relatively inexpensive is particularly preferable. Suitable aluminum plates are a pure aluminum plate and an alloy plate containing aluminum as a main component and containing a trace amount of a different element, and may be a plastic film on which aluminum is laminated or vapor-deposited. The foreign elements contained in aluminum alloys include silicon, iron, manganese, copper,
Examples include magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of the foreign element in the alloy is at most 10% by weight or less. As the aluminum plate, pure aluminum is preferable. However, since pure aluminum is difficult to produce due to refining technology, it may contain a slightly different element. As described above, the composition of the aluminum plate is not specified, and an aluminum plate of a conventionally known and used material can be appropriately used. The thickness of the aluminum plate is about 0.1 to 0.6 m
m is preferable, 0.15 to 0.4 mm is more preferable, and 0.2 to 0.3 mm is particularly preferable.

Prior to roughening the aluminum plate, if necessary, a degreasing treatment with, for example, a surfactant, an organic solvent or an alkaline aqueous solution is performed to remove rolling oil on the surface. The surface roughening treatment of the surface of the aluminum plate is performed by various methods, for example, a method of mechanically roughening the surface, a method of electrochemically dissolving the surface, and a method of selectively dissolving the surface chemically. It is performed by the method of causing. Known mechanical methods such as a ball polishing method, a brush polishing method, a blast polishing method, and a buff polishing method can be used as the mechanical method. Further, as an electrochemical surface roughening method, there is a method of performing an alternating or direct current in a hydrochloric acid or nitric acid electrolyte.

The aluminum plate thus roughened is
Alkaline etching treatment and neutralization treatment as necessary
After removal, if necessary, the water retention and abrasion resistance of the surface can be increased.
Anodizing treatment is performed for the purpose. Anodizing, by anodizing
1.0 g / m ^TwoThe above is preferred. Anodic acid
1.0 g / m^TwoIf less than, press life
Is insufficient or used as a lithographic printing plate
Indicates that the non-image area is easily scratched and
So-called "scratch stain" that ink adheres to the surface
Sometimes. After being subjected to the anodizing treatment,
The surface of the minium is subjected to a hydrophilic treatment if necessary.
You.

The concentration of the positive photosensitive composition for infrared laser (total solid content including additives) in the solvent is preferably 1 to 50% by weight. The amount of coating (solid content) on the support obtained after coating and drying varies depending on the application, but when used for the production of a photosensitive lithographic printing plate, it is generally 0.5 to 5.0 g / m2. ² is preferred.

The coating method is not particularly limited, and includes known coating methods, for example, bar coating, spin coating, spray coating, curtain coating, dip coating, air knife coating, blade coating, roll coating and the like. Can be As the amount of the coating decreases, the apparent sensitivity increases, but the film characteristics of the photosensitive layer deteriorate.

Such an image forming material is subjected to image exposure and development to produce a lithographic printing plate. As a light source of the active light beam used for the image exposure, a light source having an emission wavelength in a near infrared to infrared region is preferable, and a solid laser and a semiconductor laser are particularly preferable.

As a developing solution or a replenishing solution used in the developing treatment, a conventionally known aqueous alkaline solution can be used. For example, sodium silicate, potassium, tribasic sodium, potassium, ammonium, dibasic sodium, potassium, ammonium, sodium carbonate, potassium, ammonium, sodium bicarbonate, potassium, potassium Ammonium, sodium borate, potassium, ammonium, sodium hydroxide,
And inorganic alkali salts such as ammonium, potassium and lithium. Also, monomethylamine,
Dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, triisopropylamine, n-butylamine, monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, ethyleneimine, ethylenediamine, Organic alkali agents such as pyridine are exemplified. One of these alkaline aqueous solutions may be used alone, or two or more thereof may be used in combination.

Among these aqueous alkali solutions, aqueous silicate solutions such as sodium silicate and potassium silicate are particularly preferred. The reason is that the developability can be adjusted by the ratio and the concentration of the silicon oxide SiO ₂ and the alkali metal oxide M ₂ O which are the components of the silicate. And alkali metal silicates described in JP-B-57-7427.

When the development is performed using an automatic developing machine, an aqueous solution (replenisher) having a higher alkali strength than the developer is added to the developer to replace the developer in the developing tank for a long time. A large amount of PS plates can be favorably processed without performing.

The above-mentioned developer and replenisher may contain various surfactants and organic solvents as necessary for the purpose of accelerating or suppressing the developing property, dispersing developing scum, or enhancing the ink affinity of the printing plate image area. Solvents can be added. The surfactant is preferably an anionic, cationic, nonionic or amphoteric surfactant. Further, the developing solution and the replenisher may contain, if necessary, a reducing agent such as a sodium salt or a potassium salt of an inorganic acid such as hydroquinone, resorcin, sulfurous acid, and hydrogen sulfite; an organic carboxylic acid; an antifoaming agent; A softener or the like can be added.

The image-forming material developed using the above-mentioned developer and replenisher is post-treated with washing water, a rinsing solution containing a surfactant and the like, and a desensitizing solution containing gum arabic and a starch derivative. . As a post-process when the image forming material is used as a printing plate, these processes can be used in various combinations.

In recent years, in the plate making / printing industry, automatic developing machines for printing plates have been widely used for rationalizing and standardizing plate making operations. This automatic developing machine generally comprises a developing section and a post-processing section, and comprises a device for transporting a printing plate, each processing solution tank and a spray device, and while pumping the exposed printing plate horizontally, each pumped by a pump. The developing process is performed by spraying a processing liquid from a spray nozzle. Recently, a method has been known in which a printing plate is immersed and conveyed by a submerged guide roll or the like in a processing liquid tank filled with a processing liquid to perform processing. In such an automatic processing, the processing can be performed while replenishing each processing liquid with a replenisher according to the processing amount, the operating time, and the like. Further, a so-called disposable processing method in which processing is performed with a substantially unused processing liquid can also be applied. In such a development processing step, the evaluation method of the present invention,
By applying the quality control method, a lithographic printing plate with stable quality can be continuously obtained.

The case where the image forming material is used as a photosensitive lithographic printing plate will be described. First, after the image forming material is exposed to light and developed, it is washed and / or rinsed and / or gummed, and an unnecessary image portion (for example, a film edge mark of an original film) of the obtained lithographic printing plate is obtained. If there is, the unnecessary image portion is erased. Such erasing is preferably carried out by applying an erasing liquid as described in, for example, Japanese Patent Publication No. 2-13293, to an unnecessary image portion, leaving it for a predetermined time, and then rinsing with water. A method described in JP-A-59-174842, in which active light guided by an optical fiber is applied to an unnecessary image portion and then developed, can also be used.

The lithographic printing plate obtained as described above can be subjected to a printing step after applying a desensitizing gum as required, but when it is desired to obtain a lithographic printing plate having higher printing durability. Is subjected to a burning process. The lithographic printing plate obtained by such a process is set on an offset printing machine or the like and used for printing a large number of sheets.

[0058]

Hereinafter, the present invention will be described with reference to Examples.
The scope of the present invention is not limited to these examples. (Example 1) [Synthesis of specific copolymer 1] 31.0 g (0.36 mol) of methacrylic acid and ethyl chloroformate were placed in a 500 ml three-necked flask equipped with a stirrer, a condenser and a dropping funnel.
1 g (0.36 mol) and 200 ml of acetonitrile were added, and the mixture was stirred while cooling in an ice water bath. To this mixture, 36.4 g (0.36 mol) of triethylamine was dropped by a dropping funnel over about 1 hour. After the addition, the ice-water bath was removed, and the mixture was stirred at room temperature for 30 minutes.

51.7 g (0.30 mol) of p-aminobenzenesulfonamide was added to the reaction mixture, and the mixture was stirred for 1 hour while warming to 70 ° C. in an oil bath. After completion of the reaction, the mixture was added to 1 liter of water while stirring the water, and the resulting mixture was stirred for 30 minutes. The mixture was filtered to remove the precipitate, which was then washed with 500 m of water.
Then, the slurry was filtered and the obtained solid was dried to obtain a white solid of N- (p-aminosulfonylphenyl) methacrylamide (yield 46.9 g).

Next, 4.61 g of N- (p-aminosulfonylphenyl) methacrylamide was placed in a 20 ml three-necked flask equipped with a stirrer, a condenser and a dropping funnel.
92 mol), and 2.94 g (0.02 g) of ethyl methacrylate.
58 mol), 0.80 g (0.015 g) of acrylonitrile
Mol) and 20 g of N, N-dimethylacetamide, and the mixture was stirred while being heated to 65 ° C. in a hot water bath. This mixture was mixed with “V-65” (manufactured by Wako Pure Chemical Industries, Ltd.).
0.15 g was added, and the mixture was stirred for 2 hours under a nitrogen stream while maintaining at 65 ° C. N- (p-
Aminosulfonylphenyl) methacrylamide 4.61
g, 2.94 g of ethyl methacrylate, 0.80 g of acrylonitrile, N, N-dimethylacetamide and "V-
65 "and a mixture of 0.15 g was added dropwise with a dropping funnel over 2 hours. After the addition was completed, the obtained mixture was further stirred at 65 ° C. for 2 hours. After completion of the reaction, methanol (40 g) was added to the mixture, and the mixture was cooled. The obtained mixture was added to 2 liters of water while stirring the water. The mixture was stirred for 30 minutes, and the precipitate was taken out by filtration and dried. 15 g of a white solid was obtained. The weight average molecular weight (polystyrene standard) of this specific copolymer 1 was determined by gel permeation chromatography to be 53,000.
It was 0.

[Preparation of substrate] Aluminum 0.3 mm thick
Plate (material 1050) is washed with trichlorethylene
Degreased, nylon brush and 400 mesh pumice
Use a water suspension to grain this surface and wash well with water.
Was cleaned. Put this plate in a 25% aqueous solution of sodium hydroxide at 45 ° C.
Immerse in the solution for 9 seconds to perform etching, and after washing with water,
It was immersed in 20% nitric acid for 20 seconds and washed with water. Grain at this time
The amount of etching on the standing surface is about 3 g / m ^TwoMet. next
This plate was subjected to a current density of 15 A / dm using 7% sulfuric acid as an electrolyte.
^Two3g / m^TwoAfter providing a direct current anodic oxide coating of
Dried, and further with a 2.5% by weight aqueous solution of sodium silicate
Treat at 30 ° C for 10 seconds, apply the following undercoat liquid,
The substrate was dried at 80 ° C. for 15 seconds to obtain a substrate. Coating of coating film after drying
15mg / m^TwoMet.

[Undercoat liquid 1]-0.3 g of the following copolymer having a molecular weight of 28,000-100 g of methanol-1 g of water

[0063]

Embedded image

The following photosensitive solution 1 was prepared. The photosensitive liquid 1 was applied to the obtained substrate so that the coating amount was 1.3 g / m ² , and a lithographic printing plate 1 was obtained. [Photosensitive solution 1] ・ Fluorine-containing polymer P-6 (the following structure) 0.03 g ・ Specific copolymer 1 0.75 g ・ m, p-cresol novolak (m, p ratio = 6/4, weight average molecule) 0.25 g-p-toluenesulfonic acid 0.003 g-tetrahydrophthalic anhydride 0.03 g-cyanine dye A (the following structure) 0.017 g-Victoria Pure Blue Dye with BOH counter ion as 1-naphthalenesulfonic acid anion 0.015 g 3-methoxy-4-diazodiphenylamine hexafluorophosphate 0.02 g Fluorosurfactant 0.05 g (MegaFac F-177, Dainippon Ink and Chemicals, Inc.) 10 g of γ-butyl lactone 10 g of methyl ethyl ketone 1-methoxy-2-p Lopanol 8g

[0065]

Embedded image

Next, 20 parts of an alkali developing solution A (pH about 13) having the following composition was placed in a developing tank of a commercially available automatic developing machine LP-900H (manufactured by Fuji Photo Film Co., Ltd.) having an immersion type developing tank. One liter was charged and kept at 30 ° C. LP
In the second bath of -900H, 8 liters of tap water and in the third bath, FP-2W (manufactured by Fuji Photo Film Co., Ltd.):
8 liters of a finishing gum solution diluted with water = 1: 1 was charged.

[Composition of Alkaline Developing Solution A] D sorbit 2.5% by weight Sodium hydroxide 0.85% by weight Diethylenetriaminepenta (methylenephosphonic acid) 5Na salt 0.05% by weight Water 96.6% by weight A lithographic printing plate (650 mm) processed while replenishing the following developing replenisher B with the developing replenishment control impedance value of the built-in automatic developing machine LP-900H at 40.5 ms / cm.
× 550 mm, 0.3 mm thick) were developed 100 plates per day.

[Composition of Development Replenisher B] D sorbit 5.6 wt% Sodium hydroxide ... 2.5% by weight ・ Diethylenetriaminepenta (methylenephosphonic acid) 5Na salt ・ ・ ・ ・ ・ ・ ・ ・ ・ 0.2% by weight ・ Water ··· 91.7% by weight

Lithographic printing plate 1 (650 mm × 550 mm ×
0.3 mm thickness) to the platesetter Luxcel Pl
using an etersetter 9000 CTP (manufactured by Fuji Photo Film Co., Ltd.) (output: 216 mW, rotation speed: 100)
0 rpm, resolution 2438 dpi, image area about 20%)
, And developed for 100 plates per day and developed for 3 months. After that, first every day Luxcel Plate
27 mW (13.5 mJ / cm ² ) using an original pattern of the 9000 CTP.
From 270 mW (135 mJ / cm ² ) to 13.5
Exposure development was carried out while changing every mW (13.5 mJ / cm ² ). That is, this stepwise exposure is performed at 10%, 15%,... 90%, 95%, 1% with respect to the maximum value of the plate surface energy.
Thus, the difference in plate energy between adjacent exposed portions was 5 to 5%.
50%. Using this original pattern, clear sensitivity and solid sensitivity were determined. 40.5mJ / cm on the first day
² was solid sensitivity, and 81 mJ / cm ² was clear sensitivity.
Therefore, when the solid sensitivity deviated from the range of 33.8 to 47.2 mJ / cm ² and the clear sensitivity deviated from the range of 67.5 to 101.3 mJ / cm ² , the exposure amount was changed so as to fall within the above range. According to the developing solution management method of the present invention, development processing could be performed stably for 90 days. Since the clear sensitivity became lower than the initially set exposure amount on the 20th day, feedback was performed based on the management method of the present invention to change the set exposure amount. If the control method of the present invention is not used, the automatic developing machine is capable of obtaining a lithographic printing plate in a preferable state,
This means that it could only be operated for 0 days. This indicates that the management method of the present invention is effective.

(Example 2) [Preparation of planographic printing plate] Aluminum plate having a thickness of 0.3 mm
(Material 1050) washed with trichlorethylene and degreased
After that, nylon brush and 400 mesh pumice-water
Using a suspension, grain this surface and wash well with water.
Was. Put this plate in a 25% aqueous solution of sodium hydroxide at 45 ° C.
Etch for 9 seconds to perform etching.
It was immersed in nitric acid for 20 seconds and washed with water. Grain table at this time
Surface etching amount is about 3g / m ^TwoMet. Then this board
With 7% sulfuric acid as the electrolyte and a current density of 15 A / dm^Twoso
3g / m^TwoAfter providing a DC anodic oxide film of
Dried. This is treated with a 2.5% by weight aqueous solution of sodium silicate.
Treat at 0 ° C for 10 seconds, apply the following undercoat liquid,
The substrate was dried at 0 ° C. for 15 seconds to obtain a substrate. Coating of coating after drying
The amount is 15mg / m^TwoMet.

[Undercoat liquid 1] 0.3 g of the copolymer having a molecular weight of 28,000 0.3 g of methanol 100 g of 1 g of water

A lithographic printing plate 2 was obtained by coating the obtained substrate with the following coating solution for forming a photosensitive layer so that the coating amount was 1.8 g / m ² .

[Photosensitive solution 2] m, p-cresol novolak 1.0 g (m / p ratio = 6/4, weight average molecular weight 8,000, unreacted cresol 0.5% by weight), pyrylium salt dye B (described below) Structure: 0.1 g Phthalic anhydride 0.05 g p-Toluenesulfonic acid 0.002 g Ethyl violet counter ion converted to 6-hydroxy-β-naphthalenesulfonic acid 0.02 g Fluorosurfactant ( Megafac F-177, manufactured by Dainippon Ink and Chemicals, Inc.) 0.05 g ・ Methyl ethyl ketone 8 g ・ 1-Methoxy-2-propanol 4 g

[0074]

Embedded image

Next, 20 parts of an alkali developing solution C (pH about 13) having the following composition was placed in a developing tank of a commercially available automatic developing machine LP-900H (manufactured by Fuji Photo Film Co., Ltd.) having an immersion developing tank. One liter was charged and kept at 30 ° C. LP
In the second bath of -900H, 8 liters of tap water and in the third bath, FP-2W (manufactured by Fuji Photo Film Co., Ltd.):
8 liters of a finishing gum solution diluted with water = 1: 1 was charged.

[0076] [alkaline composition of the development processing solution C] · SiO ₂ · K ₂ O 4.0 _{wt% (K 2 O / SiO 2} = 1.1 ( molar ratio)) Citric acid 0.5% Polyethylene Glycol (weight average molecular weight = 1000) 0.5% by weight ・ Water 95.0% by weight Lithographic printing plate 2 which has been exposed (650 mm × 550 mm × 0.
(24 mm thick) was processed with LP-900H while replenishing 35 cc of a development replenisher D having the following composition each time one plate development processing was performed.

[Composition of Development Replenisher D] SiO ₂ · K ₂ O 5.0% by weight (K ₂ O / SiO ₂ = 1.1 (molar ratio)) Citric acid 0.6% by weight Polyethylene glycol (Weight average molecular weight = 1000) 0.6% by weight ・ water 93.8% by weight

A planographic printing plate (650 mm × 550 mm ×
0.24 mm thick) with a Creo Plate Setter Tr
Using the endsetter 3244F (output:
9.0W, rotation speed: 150rpm, resolution 2400dp
i, an image area of about 20%), developed 50 plates per day, and continued for 60 days. At that time, the output was first changed every day for exposure and development, and the clear sensitivity was determined. In the stepwise exposure, the difference in plate energy between adjacent exposed portions was set to 9%. On the first day, it was 71 mJ / cm ² . Therefore, the clear sensitivity is 59 to 84 mJ / cm ²
When the value was out of the range, the exposure amount was changed.

According to the developing solution management method of the present invention, development processing could be performed stably for 60 days. Since the clear sensitivity became lower than the initially set exposure amount on the 15th day, feedback was performed based on the management method of the present invention to change the set exposure amount. If the control method of the present invention is not used, the automatic developing machine is capable of obtaining a lithographic printing plate in a preferable state under the conditions of 1
This means that it could only be operated for 5 days. This indicates that the management method of the present invention is effective.

(Example 3) A lithographic printing plate prepared in the same manner as in Example 2, an automatic developing machine and a developing solution similar to those used in Example 2 were used.

A lithographic printing plate (1030 mm × 800 mm ×
0.30mm thick) with a Creo Plate Setter Tr
Using the endsetter 3244F (output:
9.0W, rotation speed: 150rpm, resolution 2400dp
i, image area about 15%), 40 plates per day
Development processing was continued for 60 days. At that time, output first every day
Exposure development was performed while changing the clear sensitivity. 1st day
Eyes are 71mJ / cm^TwoMet. So, clear sensitivity
59-84mJ / cm^TwoDevelopment time when out of range
Was changed. Specifically, click on the 10th day
A Sensitivity is 91mJ / cm ^TwoAnd the development time was 1
After changing from 2 seconds to 14 seconds, the clear sensitivity is 71mJ
/ Cm^TwoIt became. On the 18th day, the clear sensitivity is 54mJ /
cm^TwoChanged the development time from 14 seconds to 12 seconds
Clear sensitivity is 71mJ / cm^TwoIt became. 3
Clear sensitivity is 54mJ / cm on day 0^TwoBecame
Clear feeling when developing time is changed from 12 seconds to 10 seconds
The degree is 71mJ / cm^TwoIt became. On the 46th day,
Rear sensitivity is 91mJ / cm^TwoAnd the development time
When I returned from 10 seconds to 12 seconds, the clear sensitivity was 71 mJ
/ Cm^TwoIt became. After that, until the 60th day,
An image state was obtained.

According to the developing solution management method of the present invention, development processing could be performed stably for 60 days. Since the clear sensitivity became higher than the initially set exposure amount on the 10th day, unless the management method of the present invention was used, the automatic developing machine would only be able to obtain a lithographic printing plate in a favorable state for 10 days. It means that it could not work. This indicates that the management method of the present invention is effective.

[0083]

According to the present invention, a simple evaluation method for easily determining plate making conditions of a positive type image forming material for an infrared laser for direct plate making, particularly, an active state of a developer,
The results can be fed back to the exposure / development step to provide a quality control method for keeping the quality of the lithographic printing plate constant and continuously forming a uniform image.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 7/26 501 G03F 7/26 501 (72) Inventor Takashi Okuno 4,000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Fuji (72) Inventor Shuichi Takamiya 4000, Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture F-term in Fujisha Shin-Film Co., Ltd. 2H096 AA07 BA16 BA20 EA04 EA30 GA08 LA16 LA30

Claims (4)

[Claims] 1. An image forming material comprising a photosensitive layer comprising (A) a resin soluble in an aqueous alkali solution and a compound capable of absorbing light and generating heat on a support, the plate surface energy is gradually applied. Create a lithographic printing plate for evaluation that has been exposed under multiple conditions and developed with a standard developer of standard formulation.
A step of preparing a standard developer-processed lithographic printing plate; and (B) developing an evaluation lithographic printing plate exposed under the same conditions as described above with a developing solution to be evaluated; And (C) comparing the state of the image area or the non-image area of the standard developed lithographic printing plate and the target developed lithographic printing plate under predetermined exposure conditions. Image evaluation method. 2. An image forming material having a photosensitive layer containing (A) a resin soluble in an aqueous alkali solution and a compound capable of absorbing light to generate heat on a support, the plate surface energy is gradually applied. Developing a lithographic printing plate for evaluation, which has been subjected to exposure under a plurality of conditions while changing the lithographic printing plate with a standard formulation, to prepare a lithographic printing plate treated with a standard developing solution; and (B) conditions similar to those described above. Except for developing the lithographic printing plate for evaluation subjected to exposure in the same manner as the standard development lithographic printing plate, except that the lithographic printing plate is developed with a developer to be evaluated, (C) a step of comparing the state of an image portion or a non-image portion under predetermined exposure conditions of the standard developed lithographic printing plate and the target developed lithographic printing plate; and (D) comparing the image portion or the non-image portion. As a result, when the difference between the two exceeds a predetermined value And a step of adjusting exposure / development conditions. 3. In the step of performing exposure under a plurality of conditions while changing the plate surface energy stepwise to prepare a lithographic printing plate for evaluation, the difference in plate surface energy between adjacent exposed portions is as follows:
3. The quality control method for a lithographic printing plate according to claim 2, wherein the content is 3 to 50%. 4. The step (C) of comparing the state of an image area or a non-image area under predetermined exposure conditions of the standard developed lithographic printing plate and the target developed lithographic printing plate is performed by stepwise reducing the plate surface energy during exposure. Exposure and development
3. The quality control of a lithographic printing plate according to claim 2, wherein the step of comparing the plate surface energy at the minimum exposure amount at which the exposed portion is completely dissolved or at the maximum exposure amount at which the density does not change from the unexposed portion. Method.