JP4630968B2 - Aluminum alloy plate for planographic printing plate, method for producing the same and planographic printing plate - Google Patents

Description

  The present invention relates to an aluminum alloy plate for a lithographic printing plate, a method for producing the same and a lithographic printing plate, which is used after a photosensitive layer is formed in advance and subjected to a development process, or after being subjected to a baking process on the photosensitive layer, and in particular, a roughening by electrolytic etching The present invention relates to an aluminum alloy plate and a lithographic printing plate having excellent surface uniformity.

In lithographic printing, a plate in which an image portion is formed by performing plate making processing such as image exposure and development on a PS plate (Presensitized Plate) composed of an aluminum alloy plate and a photoconductor having a diazo compound or the like as a photosensitizer The ink is wound around a cylindrical plate cylinder, ink is attached to the image portion in the presence of dampening water attached to the non-image portion, the ink is transferred to a rubber blanket, and printed on a paper surface.
In general, an aluminum alloy plate subjected to surface treatment such as roughening treatment (graining) or anodizing treatment by electrolytic etching is used as a support for the PS plate. As an aluminum alloy used for this kind of application, initially, JIS1050 (pure Al type having a purity of 99.5% or more), JIS1100 (Al-0.05 to 0.20% Cu alloy), JIS3003 (Al-0. (05-0.20% Cu-1.5% Mn alloy) has been mainly used.

  This type of lithographic printing plate aluminum alloy plate has (1) a rough surface by electrolytic etching, (2) good adhesion of the photosensitive agent, and (3) an image portion during printing. Various characteristics are required such as no contamination. However, JIS 1050, JIS 1100, and JIS 3003 alloys themselves cannot sufficiently satisfy the above requirements, and various improvements have been made to the alloy composition and the obtained surface condition.

For example, the surface roughening treatment is performed for imparting water retention to the surface of the aluminum alloy plate and fixing the photosensitive layer in close contact, and the adhesion of the photosensitive layer affects the performance as a printing plate. However, in the conventional roughening treatment, unetched portions may occur on the roughened surface, and the distribution of etch pits formed by the roughening may be uneven. Is adversely affected, and it is required to improve this rough surface state.
As one of the methods, there is disclosed a method of improving the etching property by promoting the formation of etch pits by adding a predetermined amount of Ni to the material (see, for example, Patent Document 1).
In addition, a method for improving the etching property without adding a special element has been proposed by paying attention to the size and density of the intermetallic compound and controlling them (see, for example, Patent Document 2).
In this method, the intermetallic compound serves as a starting point for etching, and fine etch pits are uniformly formed. However, this method cannot sufficiently improve the etching property, and does not satisfy the above-mentioned demand.

  From the researches of the present inventors, the sufficient etching property cannot be obtained by controlling the size and density of the intermetallic compound described above, and the chemical solubility of the intermetallic compound is larger than expected, so that it can be dissolved in the electrolytic solution. It has been found that it is not sufficiently functioning as the starting point of the etching pit because it disappears. As a result of further research, it has been found that if the metastable phase AlFe-based intermetallic compound particles are appropriately dispersed, the etching property is greatly improved, and the above-described demand can be more fully met.

  Furthermore, as a result of research on this type of PS plate, the present inventor has found that when an aluminum plate is immersed in an electrolytic treatment solution while being fed from a roll and subjected to an electrolytic etching process, the direction of the aluminum plate (aluminum plate) It has been found that a stripe pattern due to etching unevenness tends to occur in a direction perpendicular to the direction in which the film is sent. This striped pattern is likely to occur especially when the line speed is increased and the electrolytic etching processing time is shortened. In the uneven part, that is, in the part where the roughening is shallow, a photosensitive layer is provided to obtain the final product of the PS plate. Even in such a state, it was found that there is a high risk that a striped pattern remains, leading to poor appearance of the coating film, low adhesion of the photosensitive film and low printing durability.

As a measure for preventing the occurrence of the stripe pattern, a method of adjusting the electrode arrangement and frequency in the electrolytic cell has been proposed (for example, see Patent Document 3).
However, this method requires a large cost for equipment improvement, and the generation of the stripe pattern is not completely improved.
JP 11-115333 A Japanese Patent Laid-Open No. 11-151870 JP 2000-17500 A

Furthermore, higher strength has been demanded for specific varieties of this type of PS plate. For example, when a PS plate is chucked on a printing roll, the end portion is bent and then wound around a printing cylinder and fixed, but this bending is a direction perpendicular to the rolling direction, that is, a direction parallel to the previous striped pattern. Therefore, there is a problem that cracks may occur in the PS plate during bending.
For example, in order to prevent the above-described stripe pattern from occurring, it is conceivable that the electrolytic etching treatment is performed with a high strength. As a result, the anode portion is subjected to etching stronger than the cathode portion. It has been found that moderately formed etch pits tend to be over-etched, and cracks are likely to occur when this over-etched portion overlaps the previous bent portion. If cracks occur in the PS plate, there is a risk of plate breakage starting from this crack.

The present invention relates to an aluminum alloy plate for a lithographic printing plate that has few unetched portions and has uniform etch pits to improve the uniformity of the roughening treatment by electrolytic etching so as not to cause a striped pattern. The first object is to provide a manufacturing method.
Further, the present invention further improves the strength, makes it difficult for cracks to occur when mounted on a printing cylinder, prevents the plate from being cut, and at the same time has excellent printing durability, and an aluminum alloy plate for a lithographic printing plate, A second object is to provide a manufacturing method thereof.
Furthermore, a third object of the present invention is to provide a lithographic printing plate in which the occurrence of the above-mentioned stripe pattern is small, the plate is not cut, and the printing durability is excellent.

As a result of studying the generation mechanism of the stripe pattern, the inventors have found that the generation of the stripe pattern corresponds to the frequency of the AC power source used during electrolytic etching.
That is, the reason why the aluminum alloy plate surface has a striped pattern is considered as follows. In the aluminum alloy plate immersed in the electrolytic solution, in the portion to which the anode-side current is applied (anode portion), aluminum is dissolved by the reaction of Al → Al ³⁺ + 3e ⁻ , and etch pits are formed to be whitened. On the other hand, in the portion to which the current on the cathode side is applied (cathode portion), gas is mainly generated by the reaction of 2H ⁺ + 2e ⁻ → H ₂ , and aluminum is hardly dissolved. As a result, it was found that a striped pattern corresponding to the AC frequency was formed.
As a result of studying an aluminum alloy material for suppressing the occurrence of stripes with reference to such a generation mechanism, the present invention has been achieved.

The aluminum alloy plate for lithographic printing plates of the present invention comprises Fe: 0.2-0.4 wt%, Si: 0.02-0.15 wt%, Cu: 0.001-0.01 wt%, Zn: 0.01 to 0.1 wt%, Mg: 0.005 to 0.1 wt%, Ti: 0.003 to 0.05 wt%, and Pb, V, Ga, Ni, Cr, Mn, Sn, and In And Zr in a total amount of 100 to 1000 ppm, the balance being made of Al and inevitable impurities, and the average value of the crystal grain size in the direction perpendicular to the rolling direction being 60 μm or less was used as an aluminum alloy plate for a lithographic printing plate.
In the present invention, the Pb is 5 to 100 ppm, the V is 5 to 100 ppm, the Ga is 5 to 100 ppm, the Ni is 5 to 150 ppm, the Cr is 5 to 150 ppm, the Mn is 5 to 160 ppm, and the Sn is 5 -60 ppm, In 90-90 ppm, Zr 5-200 ppm.

Increasing the solubility of the cathode region is effective in suppressing the occurrence of striped patterns. In other words, by increasing the solubility of the part that has undergone the cathode reaction in the direction of whitening, the difference in appearance between the anode part and the cathode part is reduced, and the occurrence of the stripe pattern is suppressed.
In the aluminum alloy plate for a lithographic printing plate of the present invention, by using an aluminum alloy having the composition and structure as described above, a uniform particle size of intermetallic compound particles that can be the starting point of an electrolytic reaction is uniformly dispersed. Since it is possible to react both the anode part and the cathode part in a well-balanced manner when electrolytic etching is performed by providing the metastable phase intermetallic compound, it can be used for a lithographic printing plate in which no stripe pattern occurs. An aluminum alloy plate can be obtained. In particular, since it contains trace elements of Pb, V, Ga, Ni, Cr, Mn, Sn, In, and Zr that increase the cathode solubility, it should be more effective in suppressing the occurrence of stripes. it can.
In addition, since the present invention improves the strength by adding an appropriate amount of Mg, it is excellent in plate cutting performance and printing durability, and together with the added amount of Mg, the alloy elements Fe, Si, Cu, Zn, and Ti. Since the content is in an appropriate range, it is possible to provide an aluminum alloy plate that has plate cutting properties and printing durability and has no stripe pattern.

An aluminum alloy plate for a lithographic printing plate according to the present invention has a plurality of intermetallic compound particles in a metal structure, and the intermetallic compound particles have an equivalent circle diameter and an average particle size of 0.1 μm or more and less than 1.0 μm. When the weight of intermetallic particles is A and the weight of particles of 1.0 μm or more is B, it is preferably an aluminum alloy plate for a lithographic printing plate having a value of (A / B) × 100 of 0.20 or more. .

  The aluminum alloy for lithographic printing plates of the present invention contains AlFe-based, AlFeSi-based, SiTi-based, etc. as intermetallic compounds, but the cathode reactivity increases as these intermetallic compounds are finely dispersed. The occurrence of striped patterns can be suppressed. Therefore, by increasing the number of fine intermetallic compounds and setting the A / B value to 0.20 or more, both the anode part and the cathode part can be reacted in a more balanced manner, so that no stripe pattern occurs. It is possible to obtain an aluminum alloy plate for a lithographic printing plate having further excellent performance in terms of plate cutting property and printing durability.

Further, in the aluminum alloy plate for a lithographic printing plate of the present invention, in the intermetallic compound particles, the number of metastable phase particles having a composition Fe / Al weight ratio of 0.6 or less is C, and the particle size is 0.1 μm or more. When the number of all intermetallic compound particles is D, it is preferable that the aluminum alloy plate for lithographic printing plates has a C / D value of 0.05 or more.

Intermetallic compounds that have a favorable effect on the etch pit shape have more Al components such as Al ₄ Fe, Al ₅ Fe, Al ₆ Fe, or Al _m Fe (4 <m < 6) than Al ₃ Fe which is a stable phase. Metastable phase. This is because by increasing the metastable phase, the effect of suppressing the generation of the stripe pattern is further increased.

  Moreover, the manufacturing method of the aluminum alloy plate for planographic printing plates of this invention is Fe: 0.2-0.4 weight%, Si: 0.02-0.15 weight%, Cu: 0.001-0.01. Wt%, Zn: 0.01-0.1 wt%, Mg: 0.005-0.1 wt%, Ti: 0.003-0.05 wt%, and Pb, V, Ga, Ni, Cr, A method of homogenizing an alloy ingot containing a total of 60 to 2000 ppm of trace elements of Mn, Sn, In, and Zr at a temperature of 550 ° C. or lower, or hot rolling without performing a homogenization process. Adopted.

  When the intermetallic compound is subjected to a homogenization treatment at a temperature exceeding 550 ° C. for several hours, it is reprecipitated and coarsened after being dissolved. Further, the metastabilized phase changes to a stabilized phase. Therefore, it is preferable to perform the homogenization at a temperature of 550 ° C. or lower, and to perform the heat treatment in a short time when processing at a higher temperature. Good results can be obtained even if the homogenization treatment is not performed.

  In the lithographic printing plate of the present invention, at least the surface roughening and anodizing treatment are applied to the surface of the above-described lithographic printing plate aluminum alloy plate, and a photosensitive layer is provided on the lithographic printing plate aluminum alloy plate. Is a lithographic printing plate.

By using the aluminum alloy plate for a lithographic printing plate according to the present invention, there are few unetched parts, uniform etch pits, and the uniformity of the roughening treatment by electrolytic etching is improved, and there is no stripe pattern. It is a printed version.
Furthermore, the lithographic printing plate of the present invention is a lithographic printing plate having improved printing durability by simultaneously improving the strength, making it difficult for cracks to occur when mounted on a printing cylinder, and preventing plate breakage.

According to the present invention, a lithographic printing plate having a uniform etch pit with few unetched portions, uniform surface roughening, and no striped pattern is obtained.
According to the present invention, since Pb, V, Ga, Ni, Cr, Mn, Sn, In, and Zr are contained in a total amount of 100 to 1000 ppm, the lithographic printing plate is excellent in cathode solubility and can suppress the occurrence of striped patterns. An aluminum alloy plate can be provided.
Furthermore, according to the present invention, since the strength has been improved, a lithographic printing plate rich in durability having excellent printing durability with no cracks occurring without being cracked when mounted on a printing cylinder. can get.

The present inventor examined the uniformity of the electrolytic etching of the aluminum alloy for PS plates, and found the following.
(1) An Al—Fe-based intermetallic compound that crystallizes or precipitates in an aluminum matrix acts as a cathode point during electrolytic etching, and controls the solubility of the aluminum alloy for PS plate.
(2) Increasing the solubility of the material at the cathode portion (cathode solubility) is effective in suppressing the occurrence of the aforementioned stripe pattern. That is, the part subjected to the cathode reaction is also whitened, so that the difference in appearance between the anode part and the cathode part is reduced, and the stripe pattern is suppressed.

From this point of view, we investigated the additive elements in aluminum alloys and investigated the action of the additive elements. It was found that additive components such as Si, Cu and Ti decrease the cathode solubility when the additive amount is increased. . However, it has been clarified that addition of Cu in the range of 0.001 to 0.01% is suitable when the addition amount of Cu is too small to lower the cathode solubility. On the other hand, it has been found that Fe, Zn, and Mg improve cathode solubility.
Further, it has been found that Pb, V, Ga, Ni, Cr, Mn, Sn, In, and Zr also improve the cathode solubility by adding a small amount. When these elements are added in a total amount of 60 to 2000 ppm, the cathode solubility is improved and the effect of suppressing the occurrence of stripes is exhibited.

  From the above results, the composition of the aluminum alloy used in the present invention is as follows: Fe: 0.2 to 0.4 wt%, Si: 0.02 to 0.15 wt%, Cu: 0.001 to 0.01 wt% Zn: 0.01-0.1 wt%, Mg: 0.005-0.1 wt%, Ti: 0.003-0.05 wt%, and Pb, V, Ga, Ni, Cr, Mn, The total amount of Sn, In, and Zr trace elements was 60 to 2000 ppm, and the remainder was limited to a composition composed of Al and inevitable impurities.

Next, the reasons for limiting each sentence will be explained.
“Fe”: 0.2 to 0.4% by weight
Fe is an element that greatly affects the generation of stripe patterns. When the Fe content is less than 0.2% by weight, the cathode reactivity is insufficient and the stripe pattern becomes remarkable. On the other hand, if the Fe content exceeds 0.4% by weight, a coarse intermetallic compound is likely to be produced, and the cathode solubility is also lowered, and the stripe pattern is easily emphasized. A preferable Fe content range is 0.25 to 0.35% by weight.
“Si”: 0.02 to 0.15 wt%
Si is an element that precipitates in the aluminum matrix and contributes to refinement of crystal grains. In order to make the Si content less than 0.02% by weight, it is necessary to use a high-purity metal, and the cost is greatly increased. On the other hand, when the Si content exceeds 0.15% by weight, the intermetallic compound is coarsened and coarse etch pits tend to be generated in the electrolytic etching portion. The range of preferable Si content is 0.05 to 0.10% by weight.

“Zn”: 0.01 to 0.1 wt%
Zn is an element that greatly affects the generation of stripe patterns. When the Zn content is less than 0.01%, the cathode solubility is insufficient, and it is difficult to obtain the effect of suppressing the occurrence of stripes. On the other hand, when the Zn content exceeds 0.1% by weight, the cathode solubility is excessively increased, and rather, the generation of a stripe pattern is promoted. A preferable Zn content range is 0.03 to 0.07% by weight.
“Ti”: 0.003 to 0.05 wt%
Ti is an element for refining crystal grains, but if the Ti content is less than 0.003% by weight, the effect of crystal refining cannot be obtained. On the other hand, when the Ti content exceeds 0.05% by weight, coarse crystallized substances increase to lower the cathode solubility and promote the generation of stripes. A preferable range of Ti content is 0.005 to 0.02% by weight.

“Cu”: 0.001 to 0.01% by weight
Cu is an element that greatly affects the generation of stripe patterns. When the Cu content is less than 0.001% by weight, the cathode solubility is insufficient. On the other hand, if the Cu content exceeds 0.01%, the cathode solubility is lowered and the generation of the stripe pattern is promoted. A preferable Cu content range is 0.002 to 0.005% by weight.
“Mg”: 0.005 to 0.1 wt%
Mg is an element that greatly affects the generation of stripe patterns. If the content is less than 0.005% by weight, the cathode solubility is insufficient, and the effect of improving the strength is small. On the contrary, if the content exceeds 0.1% by weight, the cathode solubility is reduced and stripes are generated. Will be encouraged. A preferred range is 0.02 to 0.07% by weight.

“Minor components”: 60-2000 ppm
When Pb, V, Ga, Ni, Cr, Mn, Sn, In, or Zr is added as a trace element, the effect of increasing the cathode solubility and suppressing the generation of the stripe pattern is exhibited. Since these trace elements all have the same effect, the total amount of trace elements added is suitably 60 to 2000 ppm. If it is less than 60 ppm, the effect of suppressing the occurrence of striped patterns is not exhibited, and if it exceeds 2000 ppm, the solubility in the cathode increases and the occurrence of striped patterns becomes remarkable. When the stripe pattern is generated, the adhesion of the photosensitive film is deteriorated and the printing durability is also lowered. The proper addition range of these trace elements is more preferably 100 to 1000 ppm in total.

Next, the metal structure will be described.
In an aluminum alloy used as a PS plate, the size of crystal grains affects the uniformity of etch pits. The finer the crystal grains are dispersed, the more the cathode reaction is promoted and the occurrence of stripes can be suppressed. In the aluminum alloy sheet after rolling, since the crystal grains extend in the rolling direction, it has been found that if the average value of the crystal grain size in the direction perpendicular to the rolling direction is 60 μm or less, the generation of the stripe pattern is suppressed.
When the average value of the crystal grain size exceeds 60 μm, the cathode solubility is lowered, and the generation of the stripe pattern is promoted. Furthermore, cracks are likely to occur during bending, and the plate cutting property is reduced.

The aluminum alloy as described above contains an intermetallic compound such as Al ₃ Fe, Al ₄ Fe, Al ₅ Fe, Al ₆ Fe, or Al _m Fe (4 <m <6). The more finely dispersed these intermetallic compounds are, the more the cathode reaction is promoted and the occurrence of striped patterns can be suppressed. Since the intermetallic compound particles serve as starting points of the etch pits, the size of the intermetallic compound particles affects the properties of the etch pits grown thereafter.
As a result of investigating the influence of these intermetallic compounds on the aluminum alloy plate used as the PS plate, the size of the intermetallic compound that effectively acts on the formation of etch pits is 0.1 or more and less than 1.0 μm. . If the particle size of the intermetallic compound is too small and too fine, it will not sufficiently act as the starting point of the etch pit, while if the particle size of the intermetallic compound is too large, the uniformity of the etch pit will be reduced. When the appropriate size of the intermetallic compound particles is expressed by the ratio of the particles, the amount of the intermetallic compound particles having an equivalent circle diameter and an average particle size of 0.1 μm or more and less than 1.0 μm is A, 1.0 μm or more. When the amount of particles is B, the value of (A / B) × 100 is 0.20 or more. When the value of (A / B) × 100 is less than 0.20, the cathode solubility is low, and the generation of the stripe pattern is promoted. Preferably, the value of (A / B) × 100 is 0.30 or more. The upper limit of (A / B) × 100 is about 300, and even if the upper limit is exceeded, the effect of suppressing the occurrence of striped patterns is small.

Conventionally, in an aluminum alloy plate for a lithographic printing plate, Fe ₃ Al particles, which are mainly stable phases, are dispersed among AlFe-based intermetallic compounds, and there are few metastable phase dispersion layers. In the present invention, unlike the conventional one, the surface layer portion has a metal structure in which metastable phase AlFe intermetallic compound particles are dispersed. This metastable phase is an intermetallic compound having a larger amount of Al component than the stable phase, which is represented by Al ₄ Fe, Al ₅ Fe, Al ₆ Fe, or Al _m Fe (4 <m <6). These intermetallic compounds exist alone or as a mixed phase. The metastable phase intermetallic compound particles are likely to be the starting point of etch pits compared to the stable phase intermetallic compound particles, and increase the dispersibility of the etch pits and effectively prevent the generation of unetched portions. Therefore, it is preferable that the metal structure has a large amount of metastable phase precipitated. Further, it is more effective that m of Al _m Fe is close to 6.
For these reasons, the aluminum alloy plate for a lithographic printing plate of the present invention is an intermetallic compound particle having a particle size of 0.1 μm or more, and a metastable phase particle having a component ratio of Fe / Al of 0.6 or less. When the number is C and the number of all intermetallic compound particles having a particle diameter of 0.1 μm or more is D, an aluminum alloy plate for a lithographic printing plate having a C / D value of 0.05 or more is preferable. By satisfying this condition, an effect of suppressing the generation of a stripe pattern due to the dispersion of metastable phase particles can be obtained.

Next, the manufacturing method of the aluminum alloy plate of this invention is demonstrated.
In an ordinary aluminum alloy manufacturing method, homogenization is performed for the purpose of eliminating segregation of components after melting an alloy having a target composition. At this stage, almost no metastable phase exists. Moreover, since it is sufficiently heated in the process of soaking before hot rolling, the slightly remaining metastable phase also disappears. Therefore, by performing appropriate thermal management in the manufacturing process, the metastable phase particles are sufficiently dispersed and almost disappeared.
On the other hand, the aluminum alloy plate according to the present invention, for example, mixes raw materials so as to obtain a target composition ratio, adjusts the components, and homogenizes the cast alloy ingot to obtain a metastable phase at 550. Perform at a temperature of ℃ or less, or omit homogenization. Thereafter, also in the hot rolling process, rolling is performed at a temperature of 550 ° C. or less, and then cold rolling is performed to obtain an aluminum alloy plate having a target thickness. In the cold rolling process, an annealing process may be appropriately performed.
The aluminum alloy sheet thus obtained has an average value of crystal grain size in the direction perpendicular to the rolling direction of 60 μm or less, and the equivalent grain diameter in the metal structure has an average grain size of 0.1 μm or more and 1. When the content of intermetallic compound particles of less than 0 μm is A and the content of particles of 1.0 μm or more is B, the value of (A / B) × 100 is 0.20 or more, and Fe / A metal having a C / D value of 0.05 or more, where C is the number of metastable phase particles having an Al ratio of 0.6 or less and D is the number of all intermetallic compound particles having a particle size of 0.1 μm or more. It is an aluminum alloy plate having a texture.
Since the aluminum alloy plate having such a metal structure balances the electrolytic state between the anode point and the cathode point in performing the etching process, the occurrence of a stripe pattern can be suppressed.

The aluminum alloy plate thus obtained is subjected to surface cleaning by caustic treatment using caustic soda, etc. prior to the surface roughening treatment.
The aluminum alloy plate whose surface has been cleaned is subjected to a roughening treatment for further roughening the surface. This roughening treatment is performed by electrolytic etching. In this electrolytic etching process, the aluminum alloy plate is fed by a roll, and the electrolytic process is performed while an AC voltage is applied to the electrodes. In this process, if the degree of whitening at the cathode point and the anode point is greatly different due to the relationship between the feed speed by the roll and the alternating current frequency, the aluminum alloy plate that is subjected to the electrolytic treatment is oriented perpendicular to the conveying direction (the direction along the width direction). ) Is likely to occur.

A photosensitizer is applied to the surface of the aluminum alloy plate subjected to the roughening treatment. The photosensitive agent is dried after applying a photosensitive solution comprising a photosensitive composition. As the photosensitive solution, those conventionally used in the production of photosensitive lithographic printing plates can be used.
Examples of such a photosensitive solution include (1) a positive photosensitive composition containing an o-quinonediazide compound, (2) a negative photosensitive composition containing a diazonium compound, and (3) containing an addition polymerizable unsaturated group. Negative photosensitive composition containing compound and photopolymerization initiator, (4) Positive laser photosensitive composition containing alkali-soluble resin and photothermal conversion agent, (5) Alkali-soluble resin, acid generator, crosslinking agent and photothermal A negative type laser-sensitive composition containing a conversion agent, (6) a heat-sensitive unprocessed type laser-sensitive composition containing hydrophobic heat-fusible resin fine particles, etc. dissolved or dispersed in an organic solvent Is available.
As the organic solvent, those having a boiling point in the range of 40 ° C. to 200 ° C., particularly 60 ° C. to 160 ° C. are used from the advantage of drying. Specific examples of the organic solvent include alcohols, ketones, hydrocarbons, acetates, ethers, polyhydric alcohols and derivatives thereof, dimethyl sulfoxide, N, N-dimethylformamide, methyl lactate, ethyl lactate, and the like. Is mentioned.

Examples of the method for applying the photosensitive composition include roll coating, dip coating, air knife coating, gravure coating, gravure offset coating, hopper coating, blade coating, wire doctor coating, and spray coating. The coating amount of the photosensitive composition in ^the range of 10ml / ^{m 2} ~100ml / m 2 are preferred. The photosensitive composition is usually dried by heated air. The heating is preferably in the range of 30 ° C to 200 ° C, particularly 40 ° C to 140 ° C.

Hereinafter, the present invention will be described with reference to examples and comparative examples.
(1) “Production of aluminum alloy sheets”
The raw materials are prepared so as to have the alloy composition shown in Table 1, and the slab obtained by melt casting is subjected to a homogenization treatment at a temperature of 500 ° C. to 550 ° C. or hot rolling without performing the homogenization treatment. Thus, an aluminum alloy plate having a thickness of 6 mm was obtained. Further, this aluminum alloy plate was rolled to a thickness of 0.3 mm by cold working to obtain an aluminum alloy plate.
(2) "Etching process"
The obtained aluminum alloy plate was degreased with an aqueous sodium hydroxide solution, immersed in a 2% aqueous hydrochloric acid solution at room temperature, and an alternating current of 50 Hz, 120 A / dm ² was applied between the aluminum alloy plate and the carbon electrode. And the electrolytic etching process was performed while moving this aluminum alloy plate in one direction at a speed of 30 m / min with respect to the electrode. The treated aluminum alloy plate was washed with water, neutralized by washing with 10% sulfuric acid at room temperature for 1 minute, further washed with water and dried.

  About the aluminum alloy plate obtained as described above, the crystal grain size and the amount of intermetallic compound were measured, the proportion of the intermetallic compound in the metastable phase was measured, and the occurrence of the stripe pattern was examined. These results are shown in Table 2.

Here, the crystal grain size was measured by measuring the width of crystal grains in the direction perpendicular to the rolling direction of the aluminum alloy sheet surface.
The amount of intermetallic compound particles was measured by dissolving about 1 mg of an aluminum alloy sample in 180 ° C. and 100 g of phenol, adding 100 g of benzyl alcohol and reheating to 180 ° C. The particles having a size of 1.0 μm or more were captured by filtration through a membrane filter, washed with benzyl alcohol, dried and weighed. The weight of the dry particles was set to 1.0 μm or more;
Further, the filtrate was filtered through a 0.1 μm membrane filter to capture particles of 0.1 μm or more and less than 1.0 μm, washed with benzyl alcohol, dried and weighed. The weight of the dry particles was defined as an amount of particles of 0.1 μm or more and less than 1.0 μm;
A value of (A / B) × 100 was calculated from the values of “A” and “B” thus obtained.

The ratio of the metastable phase intermetallic compound was measured by observing the surface of the aluminum alloy plate at a magnification of 3000 times using a scanning electron microscope. The measurement was performed for 20 arbitrary visual fields, and the number of particles having an equivalent circle diameter of 0.1 μm or more among the measured particles was counted as the total particle number: D.
Further, the same field of view was observed with EPMA, the ratio of Fe to Al was measured, and the number of particles having an Fe / Al value of 0.6 or less was counted to obtain the number of metastable phase particles: C. And the value of C / D was made into the ratio of the metastable phase.

  The presence or absence of striped patterns was determined by visually observing the surface of the aluminum alloy plate that had been washed and dried after electrolytic treatment. The evaluation was made with a mark “◯”, a mark “△” when the stripe pattern was slightly strongly recognized, and a mark “X” when the stripe pattern was clearly recognized.

  The plate cutting property was obtained by bending the aluminum alloy plate after the above-described electrolytic etching as a substitute specimen so that the inner angle was 15 degrees with the portion corresponding to the striped anode portion as the front side, and this bent portion was optical microscope. When the crack was observed, the mark “X” was given, and the case where the crack was not observed was marked with “◯”.

In terms of printing durability, the aluminum alloy plate subjected to the above-described electrolytic etching was subjected to a 2 A / dm ² sulfuric acid alumite treatment in a 20% sulfuric acid bath to form a 2 μm-thick sulfuric acid alumite film. The anodized aluminum alloy plate was hydrophilized and then washed with water and dried to obtain an aluminum support.
Subsequently, the coating liquid of the following Table 3 as a coating liquid of a photosensitive composition was apply | coated at low speed by the roll coater method on the aluminum support body, and it dried at 100 degreeC for 3 minutes, and was set as the photosensitive lithographic printing plate. An image was formed on the resulting photosensitive lithographic printing plate. For image formation, a film with a solid and halftone dot negative image and a step wedge of 0.15 steps are in close contact, and a metal halide lamp with an output of 2 kW provided at a position 1 m away from the photosensitive lithographic printing plate is used. The photosensitive lithographic printing plate was exposed with a stepwise exposure time. Thereafter, an exposed photosensitive lithographic printing using an automatic developing machine PD-912 manufactured by Dainippon Screen Co., Ltd. and a negative plate developer ND-1 (dilution ratio 1: 3) manufactured by Kodak Polychrome Graphics Co., Ltd. The plate was developed at 30 ° C. for 20 seconds, and Kodak Polychrome Graphics Co., Ltd. gum NF-2 was applied.
The lithographic printing plate thus obtained was attached to a printing cylinder to print 350,000 sheets, and then the occurrence of image loss was observed. Evaluation was made by giving a mark ◯ to a sample in which no image omission was observed, and an X mark to a sample in which an image omission was recognized.

  For comparison, a lithographic printing plate was produced in the same manner as in the example using an aluminum alloy plate having the composition shown in Table 4 and subjected to the homogenization treatment shown in Table 4, and the same as in the example. I made a good evaluation. The results are shown in Table 5.

Comparing the results shown in Tables 1 to 5, in Examples 1 to 19 of the present invention, there is little or no striped pattern, no plate breakage and printing durability. Excellent lithographic printing plates are obtained.
On the other hand, in Comparative Examples 1 and 2, since the Fe content is inappropriate, a striped pattern is generated, the plate is cut, and the printing durability is poor.
Since Comparative Example 3 contains a large amount of Si, the plate is broken.

Since Comparative Example 4 and Comparative Example 5 have an inappropriate Cu content as compared with Example 5 and Example 6, striped patterns occur, plate breakage occurs, and printing durability deteriorates.
Since Comparative Example 6 and Comparative Example 7 have an inappropriate Zn content as compared with Example 7 and Example 8, striped patterns occur, plate breakage occurs, and printing durability deteriorates.
Since Comparative Example 8 and Comparative Example 9 have an inappropriate Mg content as compared with Example 9 and Example 10, striped patterns occur, plate breakage occurs, and printing durability deteriorates.
Since Comparative Example 10 and Comparative Example 11 have an inappropriate Ti content as compared with Example 12, in Comparative Example 10, striped patterns were generated, plate breakage occurred, and printing durability was also deteriorated. Comparative Example 11 Although the plate is not cut, striped patterns occur and the printing durability is poor.

Since Comparative Example 12 has a small amount of component content compared to Example 14, a striped pattern occurs and printing durability is also deteriorated.
In Comparative Example 13, since the trace component content is excessively large compared to Example 19, striped patterns are generated and the printing durability is also deteriorated.
Since Comparative Example 14 has a crystal grain size that is too large compared to Example 15, striped patterns occur, causing plate breakage and poor printing durability.

According to the present invention, a lithographic printing plate having a uniform and clear printing screen can be obtained, which is extremely useful since it has excellent durability.

Claims (7)

  Fe: 0.2-0.4 wt%, Si: 0.02-0.15 wt%, Cu: 0.001-0.01 wt%, Zn: 0.01-0.1 wt%, Mg: 0.005 to 0.1 wt%, Ti: 0.003 to 0.05 wt%, and Pb, V, Ga, Ni, Cr, Mn, Sn, In and Zr in a total amount of 100 to 1000 ppm, with the balance An aluminum alloy plate for a lithographic printing plate, characterized in that consists of Al and inevitable impurities, and the average value of the crystal grain size in the direction perpendicular to the rolling direction is 60 μm or less.   5 to 100 ppm for the Pb, 5 to 100 ppm for the V, 5 to 100 ppm for the Ga, 5 to 150 ppm for the Ni, 5 to 150 ppm for the Cr, 5 to 160 ppm for the Mn, 5 to 60 ppm for the Sn, 2. The aluminum alloy plate for a lithographic printing plate according to claim 1, comprising 5 to 90 ppm of In and 5 to 200 ppm of Zr. The intermetallic compound particles having a plurality of intermetallic compound particles in the metal structure, the weight of the intermetallic compound particles having an equivalent circle diameter and an average particle diameter of 0.1 μm or more and less than 1.0 μm are A, 1.0 μm or more 3. The aluminum alloy plate for a lithographic printing plate according to claim 1, wherein a value of (A / B) × 100 is 0.20 or more when the weight of the particles is B. 4. In the intermetallic compound particles, C is the number of metastable phase particles having a composition Fe / Al weight ratio of 0.6 or less, and D is the number of intermetallic compound particles having a particle size of 0.1 μm or more. The aluminum alloy plate for lithographic printing plates according to any one of claims 1 to 3, wherein the value of / D is 0.05 or more.   Fe: 0.2-0.4 wt%, Si: 0.02-0.15 wt%, Cu: 0.001-0.01 wt%, Zn: 0.01-0.1 wt%, Mg: 0.005 to 0.1 wt%, Ti: 0.003 to 0.05 wt%, and Pb, V, Ga, Ni, Cr, Mn, Sn, In and Zr in a total amount of 100 to 1000 ppm, with the balance In producing an aluminum alloy plate for a lithographic printing plate having a composition composed of Al and inevitable impurities and having an average grain size perpendicular to the rolling direction of 60 μm or less, an alloy ingot of the above composition is 550 A method for producing an aluminum alloy plate for a lithographic printing plate, characterized by performing homogenization at a temperature of ℃ or less, or hot rolling without applying homogenization.   5 to 100 ppm for the Pb, 5 to 100 ppm for the V, 5 to 100 ppm for the Ga, 5 to 150 ppm for the Ni, 5 to 150 ppm for the Cr, 5 to 160 ppm for the Mn, 5 to 60 ppm for the Sn, The method for producing an aluminum alloy plate for a lithographic printing plate according to claim 5, comprising 5 to 90 ppm of In and 5 to 200 ppm of Zr.   The surface of the aluminum alloy plate for a lithographic printing plate according to any one of claims 1 to 4 is at least roughened and anodized, and a photosensitive layer is formed on the aluminum alloy plate for a lithographic printing plate. A lithographic printing plate characterized in that is provided.