JP2717042B2 - Aluminum alloy for lithographic printing plate and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy for lithographic printing plates having excellent ink stain resistance and a method for producing the same.

[0002]

2. Description of the Related Art Al-Fe-Si alloys (for example, Japanese Patent Publication No. 55-28)
874, JP-A-58-42493, JP-A-62-146
694, JP-B 1-35910), an alloy containing Cu (for example, JP-A-62-148295), or Cu and T
Alloys containing i (for example, JP-A-60-215725, JP-A-60-215728, and JP-A-61-272357) are used. These alloys are conventionally continuously cast,
After facing and homogenizing, the coil is wound around a coil while performing hot rolling, and then subjected to the steps of cold rolling, intermediate annealing, and cold rolling to obtain an aluminum alloy for a lithographic printing plate support. At this time, after the homogenization treatment, there is no need to cool down to room temperature, hot rolling may be performed as it is, or after homogenization treatment, after cooling to room temperature, re-heating and hot rolling may be performed. is there. In the latter case, the order of facing and homogenizing may be reversed.

On the other hand, an aluminum alloy for a lithographic printing plate support is manufactured as described above and then roughened by a method such as mechanical roughening, chemical roughening and electrochemical roughening. . Mechanical surface roughening can be performed by wire brush graining, where the aluminum surface is scratched with a metal wire, ball graining, which uses an abrasive ball and abrasive to grain the aluminum surface, or brush graining, which uses a nylon brush and abrasive to grain the surface. Done by Chemical surface roughening is performed by etching in an acid or alkali solution. Electrochemical surface roughening is carried out by alternating current electrolysis in a hydrochloric acid solution or a nitric acid solution.

[0004] The surface of the aluminum alloy roughened as described above is anodized, subjected to a hydrophilic treatment as required, and a photosensitive layer is provided thereon to form a lithographic printing plate.

[0005] When printing is performed using the lithographic printing plate manufactured as described above, the non-image portion (ink stain) may be severe. As one of the causes of ink stains, if there is a large amount of elemental Si in the aluminum alloy, this will cause defects in the anodic oxide film and reduce the hydrophilicity of that part, resulting in an increase in ink stains I know.

As a countermeasure against this problem, it is effective to reduce the amount of elemental Si in the aluminum alloy (Japanese Patent Laid-Open Nos. 62-146694 and 62-14829).
5). And as a specific method, after heating to 400-600 degreeC by the continuous annealing apparatus at the time of intermediate annealing,
There is a method of dissolving the elemental Si into the matrix by cooling at a cooling rate of 50 ° C./sec or more to 100 ° C. or less (Japanese Patent Application Laid-Open No. 62-146694). Up to 50 ° C / hr
Cool at the following average cooling rate or 350-450
A method has been proposed in which hot rolling is performed after holding at a temperature of 30 ° C. for 30 minutes or more (Japanese Patent Application Laid-Open No. 62-148295).

However, the former (JP-A-62-14669)
In the case of 4), if the temperature of the intermediate annealing is low, the incorporation of the elemental Si becomes insufficient, and the ink stain has not been completely eliminated. If the temperature of the intermediate annealing is high, the penetration of the elemental Si becomes sufficient, but the passing speed of the continuous annealing decreases,
There is a problem that the efficiency is greatly reduced. In the latter case (Japanese Patent Application Laid-Open No. Sho 62-148295), the amount of the elemental Si is not sufficiently reduced by this method alone, and the problem of ink smearing in recent printing fields requiring high quality has not been solved. .

[0008]

An object of the present invention is to provide an aluminum alloy free from ink stains by dissolving simple Si without raising the temperature of intermediate annealing, that is, without lowering the sheet passing speed, and a method for producing the same. It is something to offer.

[0009]

Means for Solving the Problems The present inventors studied the effect of the added element on the amount of elemental Si deposited, and found that if an appropriate amount of Mg was added in accordance with the Si content and the amount of Mn as an impurity, the elemental Si was added. Have been found to be less likely to occur, and the ink stain resistance has been improved, and the present invention has been completed. Furthermore, they have found that if the intermediate annealing temperature is determined in accordance with the amount of Mg, the amount of Si, and the amount of Mn as an impurity, an aluminum alloy having good ink stain resistance can be produced, and the present invention has been completed.

That is, the gist of the present invention is that Fe: 0.1
1.0 to 1.0%, Si: 0.03 to 0.30%, Mg: 0.
002% or more and less than 0.05%, Ti: 0.1% or less, and the content of Mn as an impurity is less than 0.05%,
In addition, an aluminum alloy satisfying the relational expression consisting of Mg, Mn, and Si is defined as a first invention, and the ingot of the alloy is subjected to homogenization treatment, hot rolling, and cold rolling, and then to Mg, Mn, and Si.
This is a method in which intermediate annealing is performed using a continuous annealing furnace at a temperature satisfying the relational expression, and recrystallization is performed, and then final cold rolling is performed.

[0011]

The following is a detailed description of each condition.

(1) Fe: 0.1 to 1.0% Fe increases the strength of the alloy and forms fine precipitates, thereby making the bit finer due to electrochemical surface roughening. As a result, the printing durability is improved. If it is less than 0.1%, the effect is not sufficient, and if it exceeds 1.0%, coarse crystals are increased and pits become uneven.

(2) Si: 0.03 to 0.30% Si increases the strength of the alloy and forms an Al—Fe—Si compound, which contributes to finer pits due to electrochemical surface roughening. As a result, the printing durability is improved. 0.03
%, The effect is not sufficient, and if it exceeds 0.30%, the ink stain resistance deteriorates.

(3) Mg: 0.002% or more and less than 0.05% Mg forms a compound with Si and suppresses precipitation as elemental Si. Further, even when precipitation of elemental Si occurs, the amount of precipitation is reduced, so that penetration during intermediate annealing becomes easy.
If less than 0.002%, the effect is not sufficient. Mg is 0.0
If it is 5% or more, pits at the time of electrochemical surface roughening become too fine, and the printing durability becomes poor.

(4) Ti: 0.1% or less Ga, which is an impurity in aluminum, distorts the shape of pits due to electrochemical surface roughening and impairs printing durability. Ti suppresses such an action of Ga, and as a result, the pit becomes a fine circle, and the printing durability is improved. Further, Ti makes the crystal grains of the ingot fine, and as a result, prevents the occurrence of streaks when the printing plate is processed.

On the other hand, if the Ti content exceeds 0.1%, Al-
It forms a Ti-based coarse compound, coarsens pits, and reduces printing durability.

(5) Mn as an impurity: less than 0.05% When the Mn as an impurity increases, the pits of the electrochemical surface roughening become non-uniform independently, resulting in poor printing durability. However, Mn has the effect of forming a compound with Si and suppressing the precipitation of elemental Si. As described in (6), when the amount of impurity Mn increases, the amount of Mg to be added may be reduced.

(6) 10 {2 (Mg%) + (Mn%)} ≧ (Si%) (1) The Mg content is based on the Si content and the Mn content as impurities.
Equation (1) must be satisfied. If the formula (1) is not satisfied, Mg which forms a compound with Si is insufficient, and elemental Si is likely to precipitate, resulting in ink smearing.

(7) Other Elements Other elements may include Cu, Zn, Cr and the like as long as the effects of the present invention are not impaired.

(8) Manufacturing method The aluminum alloy of the present invention is manufactured by the steps of casting, homogenization, hot rolling, cold rolling, intermediate annealing, and finish cold rolling. However, the homogenization treatment and the heating before hot rolling can also be performed. That is, after the homogenization treatment, hot rolling can be performed as it is, or hot rolling can be performed after cooling to a predetermined temperature.

[0021] Intermediate annealing is performed to recrystallize the material, and is usually performed at 300 to 600 ° C. Treat at a high temperature in order to improve the burning resistance after plate making (the material is hard to soften when heated at 250 to 300 ° C. in order to increase the strength of the photosensitive film after plate making and improve the printing durability). Continuous annealing is effective. The temperature T (° C.) of the continuous annealing is as follows: T ≧ −300 A + 460 (2) where A = 10 ｛2 (Mg%) + (Mn%)｝ − (Si
%). Since the holding time of the continuous annealing is usually short, about 0 to 60 seconds, if the equation (2) is not satisfied, S
Insufficient melting of i occurs, and the elemental Si remains to cause ink stains. Equation (2) indicates that as the Mg content increases in relation to the Si content and the Mn content as an impurity, the penetration of Si becomes more likely to occur during the intermediate annealing, and the lower temperature intermediate annealing is sufficient. Is shown.

Next, the method for treating the surface of the aluminum alloy support for a lithographic printing plate according to the present invention will be described in detail.

The graining method in the present invention is an electrolytic graining method in which an alternating current is flowed in a hydrochloric acid-based or nitric acid-based electrolytic solution to grain. In the present invention, such as a wire brush grain method in which the aluminum surface is scratched with a metal wire, a ball grain method in which the aluminum surface is grained with a polishing ball and an abrasive, and a brush grain method in which the surface is grained with a nylon brush and an abrasive. The mechanical surface roughening method may be used in combination with the electrolytic surface roughening method.

Prior to the electrolytic surface-roughening treatment, the rolling oil adhering to the aluminum surface or the abrasive which has been mechanically roughened (if mechanical surface-roughening is applied) is removed to clean the surface. A surface treatment is performed to convert the surface into a surface. Typically,
For removing the rolling oil, a method of cleaning the surface using a solvent such as trichlene or a surfactant is used. Also, 1-3
The aluminum alloy plate is immersed in an aqueous solution of 0% sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate or the like at a temperature of 20 to 80 ° C. for 5 to 250 seconds to perform alkali etching, and then 10 to 30% nitric acid Alternatively, the method of immersing in a sulfuric acid aqueous solution at a temperature of 20 to 70 ° C. for 5 to 250 seconds to neutralize and remove the smut is generally used for removing both the rolling oil and the abrasive. .

After cleaning the surface of the aluminum alloy plate,
An electrolytic surface roughening treatment is performed.

In the present invention, the electrolytic solution used for the electrolytic surface roughening treatment has a concentration of 0.01 when a hydrochloric acid solution is used.
３3% by weight, preferably 0.05 to 3% by weight.
More preferably, it is in the range of ~ 2.5% by weight. When a nitric acid solution is used, the concentration is 0.2 to 5% by weight, preferably 0.5 to 3% by weight.

The electrolyte may contain a nitrate, if necessary.
Corrosion inhibitors (or stabilizers) such as chlorides, monoamines, diamines, aldehydes, phosphoric acid, chromic acid, boric acid, and oxalic acid, and grain uniforming agents can be added.

The temperature of the electrolytic solution is usually from 10 to 60 ° C. As the alternating current used at this time, any of a rectangular wave, a trapezoidal wave, and a sine wave can be used as long as the positive and negative polarities are alternately converted. Phase alternating current can be used. The current density is preferably 5 to 100 A / dm ² , and the treatment is preferably performed for 10 to 300 seconds.

The surface roughness of the aluminum alloy support in the present invention is adjusted according to the quantity of electricity, and is 0.2 to 0.8 μm.
m. When the thickness exceeds 0.8 μm, the extremely roughened surface is extremely covered with macro pits, which causes a decrease in printing durability and causes ink stains, which is not preferable. On the other hand, if the thickness is less than 0.2 μm, the dampening solution on the printing plate cannot be controlled, so that the halftone dot portion of the shadow portion tends to be limp, and a good printed matter cannot be obtained.

The smut adhered to the surface of the grained aluminum alloy is removed with 10 to 50% hot sulfuric acid (40 to 60 ° C.) or diluted alkali (such as sodium hydroxide). When removed with alkali, it is subsequently neutralized by immersion in an acid (nitric acid or sulfuric acid) for cleaning.

After de-smutting the surface, an anodic oxide coating is provided. As the anodic oxidation method, a conventionally well-known method can be used, but sulfuric acid is used as the most useful electrolytic solution. Subsequently, phosphoric acid is also a useful electrolyte. Further, the mixed acid method of sulfuric acid and phosphoric acid disclosed in JP-A-55-28400 is also useful.

In the sulfuric acid method, the treatment is usually performed with a direct current, but an alternating current can also be used. The concentration of sulfuric acid is 5
Used at 30%, 5-25 in a temperature range of 20-60 ° C
Electrolytic treatment is performed for 0 second to provide an oxide film of 1 to 10 g / m ^{2 on} the surface. Further, the current density at this time is 1 to 20
A / dm ² is preferred. In the case of the phosphoric acid method, 5 to 50
% At a temperature of 30 to 60 ° C. for 10 to 300 seconds,
It is processed at a current density of 1 to 15 A / dm ² .

After providing the anodic oxide film in this manner, post-treatment can be performed as required. For example, a method of immersion treatment in an aqueous solution of polyvinylphosphonic acid disclosed in British Patent No. 1230447, US Pat.
A method of dipping in an aqueous solution of an alkali metal silicate disclosed in Japanese Patent No. 181461 is used. It is also possible to provide a hydrophilic polymer undercoat layer if necessary,
It is selected depending on the properties of the photosensitive material provided thereafter.

The support produced by the production method of the present invention can be provided with a photosensitive layer as exemplified below to form a lithographic printing plate.

[I] o of the polyhydroxy polymer compound
When a photosensitive layer containing a naphthoquinonediazidesulfonic acid ester and a novolak resin of a mixture of phenol and cresol is provided.

As the polyhydroxy polymer compound,
Those having an average molecular weight of 1,000 to 7000 are used. For example, a polycondensate of a phenol compound (eg, resorcinol, pyrogallol, etc.) and an aldehyde compound (eg, formalin, benzaldehyde, etc.) having two or more hydroxy groups on a benzene ring is used. is there. Other examples include phenol-formaldehyde resin, cresol-formaldehyde resin, p-tert-butylphenol-formaldehyde resin, and phenol-modified xylene resin. A more preferred novolak resin is a novolak resin containing a relatively high molecular weight phenol.
Phenol-m-cresol-formaldehyde novolak resin disclosed in US Pat. Also, in order to form a visible image upon exposure, o-naphthoquinonediazide-4-sulfonyl chloride, an inorganic anion salt of p-diazophenylamine, a trihalomethyloxadiazole compound, a trihalomethyloxadiazole compound having a benzofuran ring, etc. A compound that generates a Lewis acid by the light of the above is added. On the other hand, as a dye,
Triphenylmethane dyes such as Victoria Blue BOH, Crystal Violet, and Oil Blue are used.
As a photosensitive composition comprising these components as a solid content,
0.5 to 3.0 g / m ^{2 is} provided.

[II] When a photosensitive layer containing a diazo resin and a water-insoluble and lipophilic polymer compound having a hydroxyl group is provided.

As described above, after the anodic oxide film is provided, it is immersed in an alkali metal silicate bath disclosed in US Pat. No. 3,181,461. It is preferable to provide a photosensitive layer containing a water-insoluble and lipophilic high molecular compound having a hydroxyl group and a PF ₆ salt or BF ₄ of a diazo resin, an organic salt of a diazo resin, or the like on the surface thus treated. When such a photosensitive layer is coated on the surface of the support according to the present invention, a photosensitive lithographic printing plate having excellent storage stability and visibility, and particularly stable under severe conditions such as high temperature and high humidity can be obtained.

The diazo resin for this purpose is PF ₆ salt or B
Consisting of F ₄ salt and an organic salt, triisopropylnaphthalenesulfonic acid, 4,4′-biphenyldisulfonic acid, 5-
Sulfosalicylic acid, 2,5-dimethylbenzenesulfonic acid, 2-nitrobenzenesulfonic acid, 1-naphthol
Examples thereof include aromatic sulfonic acids such as 5-sulfonic acid and p-toluenesulfonic acid, and aromatic sulfonic acids containing a hydroxyl group such as 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid.

The hydroxyl-containing polymer compound is a compound having a weight average molecular weight of 5,000 to 500,000, for example,
(1) a copolymer of N- (4-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) methacrylamide, N- (4-hydroxynaphthyl) methacrylamide and other monomers, (2) o- And (3) copolymers of o-, m- or p-hydroxyphenyl methacrylate and other monomers with other monomers.

Examples of the monomer include (a) α, β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid and maleic anhydride.

(Ii) Alkyl acrylates such as methyl acrylate and ethyl acrylate.

(C) Alkyl methacrylates such as methyl methacrylate and ethyl methacrylate.

(D) Acrylamide or methacrylamides such as acrylamide and methacrylamide.

(E) Vinyl esters such as ethyl vinyl ether and hydroxyethyl vinyl ether.

(F) Styrenes such as styrene and α-methylstyrene.

(G) Vinyl ketones such as methyl vinyl ketone.

(H) Olefins such as ethylene, propylene and isoprene.

(Ii) N-vinylpyrrolidone, N-vinylcarbazole, acrylonitrile, methacrylonitrile and the like, and any other monomer which can be copolymerized with a monomer containing an aromatic hydroxyl group.

The oil-soluble dye added to the photosensitive layer is
Preferred are Victoria Pure Blue BOH, Crystal Violet, Victoria Blue, Methyl Violet, Oil Blue # 603 and the like. In order to form a photosensitive layer having these compositions, a fluorine-based surfactant, a nonionic surfactant, a plasticizer (eg, dibutyl phthalate, polyethylene glycol, diethyl phthalate, trioctyl phosphate, etc.) and a known stabilizer ( For example, phosphoric acid, phosphorous acid,
Organic acid) and the like, and the coating weight after drying is 0.5-2.
It is provided to be 5 g / m ² .

[III] A case where a photosensitive layer comprising a photopolymerizable photosensitive composition containing a polymer having a carboxylic acid residue or a carboxylic anhydride residue, an addition polymerizable unsaturated compound and a photopolymerization initiator is provided.

In the case of a photopolymerizable photosensitive material, the surface of the support grained in a hydrochloric acid bath is preferably anodized with phosphoric acid or a mixed acid of phosphoric acid and sulfuric acid.

After anodic oxidation in a phosphoric acid bath and silicate treatment, a photopolymerization type photosensitive polymer containing a polymer having a carboxylic acid residue or a carboxylic anhydride residue, an addition-polymerizable unsaturated compound and a photopolymerization initiator. A layer of a hydrophilic composition is provided. Further, it can be used for a lithographic printing plate using an electrophotographic photosensitive member as disclosed in JP-A-60-107042.

The printing plate thus formed has good storability, and the surface of the exposed aluminum plate in the non-image area is hardly stained with printing ink, and has good hydrophilicity to quickly remove the stained ink. And has high adhesive strength to the photosensitive layer.

The polymer having a carboxylic acid residue or a carboxylic anhydride residue suitable for this purpose is preferably a polymer having a structural unit selected from the following [A] to [D].

[0056]

Embedded image

(Wherein R ₁ and R ₄ represent a hydrogen atom or an alkyl group, R ₃ represents an alkylene group which may have a phenylene group or a hydroxy group, R ₅ represents a hydrogen atom or a substituent An optionally substituted alkyl group, R ₆ represents an optionally substituted alkyl group, an allyl group or an aryl group or a cycloalkyl group, and n represents 0 or 1). The formula (A) includes acrylic acid, methacrylic acid, crotonic acid, vinylbenzoic acid, and the like, and the formula (B) includes maleic acid, monohydroxyalkyl maleate, monocyclohexyl maleate, and the like. Examples of C) include maleic acid monoalkylamides and maleic acid monohydroxyalkylamides. Formula (D) includes maleic anhydride, itaconic anhydride and the like. Is mentioned. As the polymer, those having an average molecular weight of 1,000 to 100,000 are usually used.

The addition-polymerizable unsaturated compound is an ethylenically unsaturated double compound which, when the photopolymerizable photosensitive resin composition is irradiated with actinic rays, mutually undergoes addition polymerization in three-dimensional directions to cause insolubilization. It is a monomer having a bond. Examples thereof include unsaturated carboxylic acids, esters of unsaturated carboxylic acids and aliphatic polyhydroxy compounds, esters of unsaturated carboxylic acids and aromatic polyhydroxy compounds, and the like.

The photopolymerization initiator includes benzoin, benzoin alkyl ether, benzophenone, anthraquinone,
Michler's ketone or the like can be used alone or in combination, and is provided so as to have a coating amount after drying of 1 to 3 g / m ² .

A lithographic printing plate is manufactured as described above.

[0061]

EXAMPLES The present invention will be described below in more detail with reference to examples.

Example 1 No. 1 shown in Table 1 1 to No. The alloy of No. 14 was melted and cast, and both surfaces were chamfered to a thickness of 500 mm and a width of 1000 mm.
A 3500 mm long ingot was subjected to a homogenization treatment at 540 ° C., heated to 400 ° C., hot-rolled, then cold-rolled, and heated at 500 ° C. (without holding) in a continuous annealing furnace. After the intermediate annealing, finish cold rolling was performed at a sheet thickness reduction rate of 80% to obtain a 0.30 mm thick alloy sheet.

The mechanical properties of the alloy plate thus obtained were examined. In addition, a single Si sample was observed with a transmission electron microscope (TEM).
Was examined.

Next, the surface of the alloy plate having a thickness of 0.30 mm was roughened with a rotating nylon brush in a suspension of pumicestone and water, and then chemically etched with a 10% aqueous sodium hydroxide solution. , 20% nitric acid, neutralization and washing at a temperature of 20 ° C, and 1.5% nitric acid electrolyte at a current density of 30 A / d
Alternating current electrolysis was performed at 50 ° C. for 10 seconds at m ² .

Subsequently, the surface was cleaned by immersion in a 50% aqueous solution of 15% sulfuric acid for 3 minutes, and then an oxide film of 3 g / dm ² was applied in an electrolyte containing 20% sulfuric acid at a bath temperature of 30 ° C. Provided.

The thus prepared sample was provided with the following photosensitive layer so that the coating amount upon drying was 2.5 g / m ² .

1. Naphthoquinone (1,2) -diazide- (2) -5 ester compound of sulfonic acid chloride and resorcin-benzaldehyde resin 1 part by weight Phenol and m-, p-mixed cresol and formaldehyde copolycondensation resin 5 parts by weight 2-trichloromethyl-5- [β- (2′-benzofuryl) vinyl] -1,3,4-oxadiazole 0.03 parts by weight Victoria Pure Blue BOH (manufactured by Hodogaya Chemical) 0.1 part by weight o-Naphthoquinonediazidosulfonic acid ester of p-butylphenol benzaldehyde novolak resin 0.05 parts by weight Methyl cellosolve 27 parts by weight Using a 3 KW metal halide lamp at a distance of 1 m for 50 seconds, and 25% aqueous solution of 4% sodium metasilicate. Develop at 45 ° C for 45 seconds, wash and dry Thereafter, gumming was performed to obtain a lithographic printing plate.

After observing streaks (streaks) on the surface of the printing plate, these printing plates were attached to an offset printing machine KOR, and stains (ink stains) in the non-image area and printing durability (a period until the printed matter became unclear) were obtained. (Represented by the number of prints).
The pit pattern due to the electrochemical surface roughening was observed with an electron microscope (SEM).

Table 2 shows the above results.

Inventive Example No. In the case of 1 to 5, the tensile strength is as high as 137 MPa or more, no elemental Si is observed, and the ink stain is extremely small. Also, the pit pattern is fine and uniform, and the number of printed sheets is as large as 100,000 to 110,000.

Comparative Example No. Sample No. 6 has a low strength, a slightly poor pit pattern, and a small number of printed sheets due to a small amount of Fe. No. No. 7 has a poor pit pattern due to a large amount of Fe, and the number of printed sheets is small. No. No. 8 has low strength due to low Si, and the pit pattern is slightly poor.
The number of prints is also small. No. 9 is a simple substance S because of much Si
i is large and ink stains are large. No. Since No. 10 does not contain Mg and does not satisfy the expression (a), the amount of simple substance Si is slightly large, and the ink stain is large. No. No. 11 has too much Mg, so the pit pattern is too fine, and the number of printed sheets is small. No.
No. 12 has a streak because it does not contain Ti. No. In No. 13, the pit pattern becomes uneven because of a large amount of Ti, and the number of printed sheets is small. No. In No. 14, since the Mn is large, the pit pattern becomes uneven and the number of printed sheets is small.

Example 2 No. 2 in Table 1 A plate having a thickness of 0.30 mm was obtained in the same manner as in Example 1 for the alloys 1, 2, 3, 9, and 10. Here, the temperature of the intermediate annealing was changed in the range of 420 to 540 ° C. The same processing as in Example 1 was performed on the obtained alloy plate, a printing plate was obtained, and offset printing was performed to examine the ink stainability.

The results are shown in Table 3, where A = 10 ｛2 (Mg
%) + (Mn%)｝-(Si%) and the relationship between the intermediate annealing temperature are shown in FIG. The alloy No. of the present invention. 1,
In the case of Comparative Examples 2 and 3, 9 and 10, the ink stain resistance is excellent at a considerably low temperature. A ≧ 0 T ≧ −300 A + 460 where A = 10 {2 (Mg%) + (Mn%)} − (Si
%), The ink stain resistance is good in the area surrounded by.

[0074]

[Table 1]

[0075]

[Table 2]

[0076]

[Table 3]

[0077]

As described above, according to the alloy of the present invention, it is possible to dissolve the elemental Si without increasing the temperature of the intermediate annealing, that is, without lowering the sheet passing speed and lowering the efficiency, and to contaminate the ink. Problem can be solved. Its economic and energy-saving effects are great.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the alloy composition, the intermediate annealing temperature and the ink stain resistance in the present invention.

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Shin Nobuchi 5-11-3 Shimbashi, Minato-ku, Tokyo Inside Sumitomo Light Metal Industries Co., Ltd. (72) Inventor Kido Open 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries, Ltd. (72) Inventor Yoshinori Hotta 4000, Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Fuji Photo Film Co., Ltd. (72) Hirokazu Sakaki 4000, Kawajiri, Yoshida-cho, Harihara-gun, Shizuoka Fuji Fuji Photo Film Stock In company

Claims (2)

(57) [Claims] 1. Fe: 0.1 to 1.0% (weight basis, the same applies hereinafter) Si: 0.03 to 0.30% Mg: 0.002% or more and less than 0.05% Ti: 0.1 % Or less An aluminum alloy for a lithographic printing plate, characterized in that the balance consists of Al and inevitable impurities, the content of Mn as impurities is less than 0.05%, and the following formula (1) is satisfied. 10 {2 (Mg%) + (Mn%)} ≧ (Si%) (1) 2. Fe: 0.1 to 1.0% Si: 0.03 to 0.30% Mg: 0.002% or more and less than 0.05% Ti: 0.1% or less Residual Al and unavoidable impurities And an ingot having an Mn content of less than 0.05% as an impurity and satisfying the following formula (1) is homogenized, hot-rolled, and cold-rolled. 2) A method for producing an aluminum alloy for a lithographic printing plate, comprising performing intermediate annealing using a continuous annealing furnace at a temperature satisfying the expression, recrystallizing, and then performing final cold rolling. 10 {2 (Mg%) + (Mn%)} ≧ (Si%) (1) T ≧ −300 A + 460 (2) where the above formula (2) is used. Medium, T: Intermediate annealing temperature (° C.) A = 10 2 (Mg%) + (Mn%)}-(Si%)