JPH05309964A - Aluminum alloy for lithography printing plate and preparation thereof - Google Patents

Abstract

PURPOSE:To avoid occurrence of staining due to ink by incorporating a proper amt. of Mg in accordance with Si content and the amt. of Mn as an impurity and furthermore, specifying an intermediate annealing temp. in accordance with the amt. of Si and the amt. of Mn as the impurity. CONSTITUTION:The title alloy is obtd. in such a way that it consists of 0.1-1.0% Fe, 0.03-0.30% Si, 0.002-0.05% Mg, at most 0.1% Ti, at most 0.02% Cu, the remaining part of Al and unavoidable impurities all in terms of wt. base and the content of Mn as an impurity is less than 0.05% and formulas I and II are satisfied. After homogenizing treatment, hot rolling and cold rolling of a cast mass of this alloy are performed, intermediate annealing is performed at a temp. where the formula III [wherein T is the intermediate annealing temp. ( deg.C) and A=10{2(Mg%) + (Mn%)}-(Si%) is satisfied and then, recrystallization and final cold rolling are successively performed to manufacture the title alloy.

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 a lithographic printing plate having excellent ink stain resistance and electrochemical roughening property, and a method for producing the same.

[0002]

2. Description of the Related Art An aluminum alloy for a support of a lithographic printing plate is an Al--Fe--Si type alloy (for example, Japanese Patent Publication No. 55-28
874, JP-A-58-42493, and JP-A-62-146.
694, Japanese Examined Patent Publication No. 1-35910), and 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 chamfering and homogenizing treatment, the aluminum alloy for a lithographic printing plate support is taken up by winding it into a coil while performing hot rolling, and then performing cold rolling, intermediate annealing and cold rolling. At this time, after the homogenization treatment, it may not be cooled to room temperature and may be hot-rolled as it is, or after the homogenization treatment, it may be cooled to room temperature and then reheated to be hot-rolled. is there. In the latter case, the order of chamfering and homogenization may be reversed.

On the other hand, the aluminum alloy for a lithographic printing plate support is manufactured as described above and then roughened by a method such as mechanical surface roughening, chemical surface roughening and electrochemical surface roughening. .. Mechanical surface roughening includes a wire brush grain method of scratching the aluminum surface with a metal wire, a ball grain method of graining the aluminum surface with a polishing ball and an abrasive, or a brush grain method of graining the surface with a nylon brush and an abrasive. Done by Chemical surface roughening is performed by etching in an acid or alkaline solution. Further, the electrochemical graining is performed by AC electrolysis in a hydrochloric acid solution or a nitric acid solution.

The surface of the aluminum alloy that has been roughened as described above is anodized, and if necessary hydrophilic treatment is performed, and a photosensitive layer is provided thereon to obtain a lithographic printing plate.

When printing is performed using the lithographic printing plate manufactured as described above, stains (ink stains) on the non-image area may be severe. As one of the causes of ink stains, if a large amount of elemental Si is present in the aluminum alloy, this will cause defects in the anodic oxide film and reduce the hydrophilicity of that part, resulting in increased 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). Then, as a specific method, after heating to 400 to 600 ° C. by a continuous annealing device during intermediate annealing, 1
There is a method in which elemental Si is melted in a matrix by cooling to 100 ° C. or lower at a cooling rate of 50 ° C./sec or more (Japanese Patent Laid-Open No. 62-146694). Up to 50 ℃ / hr
Cool at the following average cooling rates or 350-450
A method has been proposed in which hot rolling is carried out after holding at a temperature of 30 ° C. for 30 minutes or longer (JP-A-62-148295).

However, the former (JP-A-62-14669)
In the case of 4), if the temperature of the intermediate annealing is low, the melting of the simple substance Si becomes insufficient, and the ink stain is not completely eliminated. If the temperature of the intermediate annealing is high, the melting of elemental Si will be sufficient, but the strip speed of continuous annealing will be low,
There is a problem that the efficiency is drastically reduced. In the case of the latter (Japanese Patent Laid-Open No. 62-148295), the amount of simple substance Si cannot be reduced sufficiently by this method alone, and the problem of ink stain has not been solved in the printing field requiring high quality in recent years. .

Next, as another problem in using an aluminum alloy as a support for a lithographic printing plate, the size of pits formed by electrochemical graining becomes uneven or becomes shallow. Therefore, the printing durability may be poor.

[0009] As a method of making the pits deep and uniform by electrochemical graining to improve printing durability, 0.005-
It has been proposed to add 0.05% Cu (JP-A-3-122241). However, when Cu is added, the effect is large under appropriate processing conditions, but pretreatment conditions (for example, chemical concentration in chemical etching before electrochemical graining, etching solution temperature and etching time, or Chemical concentration in the neutralization treatment after chemical etching, temperature and treatment time of the neutralization bath), or electrochemical roughening conditions (for example, the time from immersion in the solution to energization,
If the electrolysis current density) or the like is slightly changed, a locally insufficiently etched portion (a local area where no pits are formed) is generated during electrochemical graining, resulting in poor printing durability. Therefore, the processing conditions are largely restricted, which is not industrial or economical. In other words, in order to strictly control the chemical concentration, if the liquid is frequently replaced, or if the processing time fluctuates on the processing line, the material becomes a defective product, and the processing speed is arbitrary. It was difficult to change to, and industrial and economic problems remained.

[0010]

DISCLOSURE OF THE INVENTION According to the present invention, an ink is prepared by melting Si as a simple substance without increasing the temperature of intermediate annealing, that is, without reducing the striping speed, and adding Cu as an alloy component. It is an object of the present invention to provide an aluminum alloy which is free from stains and has good printing durability, and a method for producing the same.

[0011]

Means for Solving the Problems The present inventors have studied the effect of additional elements on the precipitation amount of elemental Si, and if a proper amount of Mg is added according to the Si content and the amount of Mn as an impurity, elemental Si It has been found that the precipitation resistance to ink is less likely to occur, and the ink stain resistance is improved. Further, if the intermediate annealing temperature is determined according to the Mg content, the Si content and the Mn content as impurities, aluminum with good ink stain resistance is obtained. It has been found that alloys can be produced.

Further, the influence of the additive element on the occurrence of local etching shortage (a phenomenon in which no pit is locally formed) at the time of electrochemical graining is examined, and the Cu content is set to 0.
It is suppressed to 020% or less and (Mg%)-(Cu
%) ≧ −0.01, more preferably (Mg%) − (Cu
%) ≧ 0, it has been found that the problem of local insufficient etching can be solved without being affected by fluctuations in processing conditions. The present invention has been completed as described above.

That is, the present invention is an aluminum alloy for a lithographic printing plate as described in the claims and a method for producing the same.

[0014]

The operation will be described in detail below.

(1) Fe: 0.1 to 1.0% Fe increases the strength of the alloy and produces fine precipitates, which makes the bits fine by electrochemical roughening. As a result, printing durability is improved. If it is less than 0.1%, the effect is not sufficient, and if it exceeds 1.0%, coarse crystallized substances increase and conversely the pits become nonuniform.

(2) Si: 0.03 to 0.30% Si increases the strength of the alloy and forms an Al-Fe-Si compound, which contributes to the miniaturization of pits by electrochemical graining. As a result, printing durability is improved. 0.03
If it is less than 0.3%, 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 simple Si. Further, even when the precipitation of elemental Si occurs, the precipitation amount is reduced, so that it becomes easy to perform the infiltration during the intermediate annealing.
If it is less than 0.002%, the effect is not sufficient. Mg is 0.0
If it is 5% or more, the pits at the time of electrochemical roughening become too fine, resulting in poor printing durability.

Further, Mg makes it difficult to cause local etching shortage during electrochemical graining. The appropriate addition amount is determined in relation to the amount of Cu, as will be described later.

(4) Ti: 0.1% or less Ga, which is an impurity in aluminum, distorts the shape of pits due to electrochemical 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 finer, and as a result, prevents the generation of streak patterns (streaks) when processed as a printing plate.

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

(5) Cu: 0.020% or less Cu makes the pits for electrochemical surface roughening deep and uniform, and improves printing durability. However, if it exceeds 0.020%, local etching shortage is likely to occur due to fluctuations in processing conditions, resulting in poor printing durability. Further, the amount of Cu, which is apt to cause local insufficient etching, is also related to the amount of Mg, and in this relationship, an appropriate addition amount is determined as described later.

(6) Mn as an impurity: less than 0.05% If the amount of Mn as an impurity increases, the pits for electrochemical graining become independent and non-uniform, resulting in poor printing durability. However, Mn has the effect of forming a compound with Si to suppress the precipitation of elemental Si, and as described in (7), when the amount of impurity Mn is large, the amount of Mg to be added may be small.

(7) 10 {2 (Mg%) + (Mn%)} ≧ (Si%) (1) The Mg content is based on the Si content and the Mn content as impurities.
It is necessary to satisfy the formula (1). If the formula (1) is not satisfied, Mg forming a compound with Si will be insufficient, and simple Si will be easily deposited, resulting in ink stains.

(8) (Mg%) − (Cu%) ≧ −0.01 (2) The amount of Mg and the amount of Cu must satisfy the formula (2). If the formula (2) is not satisfied, it is likely to be affected by fluctuations in the processing conditions, and local etching shortage is likely to occur during electrochemical graining.

In order to completely solve the problem of local etching deficiency, it is more desirable to satisfy (Mg%)-(Cu%) ≧ 0 .................... (2 ').

(9) Manufacturing Method The aluminum alloy of the present invention is manufactured by the steps of casting-homogenizing treatment-hot rolling-cold rolling-intermediate annealing-finish cold rolling. However, the homogenization treatment and the heating before hot rolling can be combined. That is, it is possible to carry out hot rolling as it is after the homogenization treatment, or to carry out hot rolling after cooling to a predetermined temperature.

The intermediate annealing is performed to recrystallize the material and is usually performed at 300 to 600 ° C. In order to enhance the burning resistance after plate-making (the property that the material is hard to be softened when heated at 250 to 300 ° C. to increase the strength of the photosensitive film after plate-making and improve the printing durability), it is treated at a high temperature. Continuous annealing is effective. The temperature T (° C.) of continuous annealing is T ≧ −300A + 460 ……………………………… (3) where A = 10 {2 (Mg%) + (Mn%)}-(Si
%) Is satisfied. Since the holding time of continuous annealing is usually as short as 0 to 60 seconds, if the formula (3) is not satisfied, S
Melting of i becomes insufficient, and simple substance Si remains to cause ink stain. In the equation (3), in relation to the Si content and the amount of Mn as an impurity, the larger the amount of Mg, the more easily Si is infiltrated during the intermediate annealing, and the lower temperature intermediate annealing is sufficient. Is shown.

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

The graining method in the present invention is an electrolytic graining method of graining by passing an alternating current in a hydrochloric acid or nitric acid electrolyte. In the present invention, such as a wire brush grain method of scratching the aluminum surface with a metal wire, a ball grain method of graining the aluminum surface with a polishing ball and an abrasive, and a brush grain method of graining the surface 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 bitten after the mechanical surface-roughening (when mechanically surface-roughened) is removed to clean the surface. A surface treatment is performed to convert the surface. Typically,
For removing rolling oil, a method of cleaning the surface with 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 for alkali etching, and then 10 to 30% nitric acid. Alternatively, a method of immersing in a sulfuric acid aqueous solution at a temperature of 20 to 70 ° C. for 5 to 250 seconds to perform neutralization and smut removal is generally used for both removal of rolling oil and removal of abrasives. ..

After cleaning the surface of this aluminum alloy plate,
Electrolytic surface roughening treatment is performed.

The electrolytic solution used for electrolytic graining treatment in the present invention has a concentration of 0.01 when a hydrochloric acid solution is used.
Is preferably used in the range of
It is even more preferable if it is up to 2.5% by weight. When the nitric acid solution is used, the concentration is 0.2 to 5% by weight, preferably 0.5 to 3% by weight.

If necessary, the electrolytic solution contains nitrates,
Corrosion inhibitors (or stabilizers) such as chlorides, monoamines, diamines, aldehydes, phosphoric acid, chromic acid, boric acid and oxalic acid, and a grain leveling agent can be added.

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

The surface roughness of the aluminum alloy support in the present invention is adjusted to 0.2 to 0.8 μm by adjusting the amount of electricity.
m. If it exceeds 0.8 μm, the macro-roughened surface is extremely covered with macro pits, which causes deterioration of printing durability and ink stains, which is not preferable. On the other hand, if it is less than 0.2 μm, the dampening water on the printing plate cannot be controlled, and the halftone dot portions of the shadow portion are likely to be colored, so that a good printed matter cannot be obtained.

In the grained aluminum alloy, the smut adhering to the surface is removed by 10 to 50% hot sulfuric acid (40 to 60 ° C.) or a dilute alkali (sodium hydroxide or the like). If removed with alkali, subsequently, for cleaning, soak in acid (nitric acid or sulfuric acid) for neutralization.

After removing the surface smut, an anodic oxide film is provided. As the anodizing method, a conventionally well-known method can be used, but sulfuric acid is used as the most useful electrolytic solution. Then 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 carried out with a direct current, but it is also possible to use an alternating current. The concentration of sulfuric acid is 5
Used at 30%, 5 to 25 in the temperature range of 20 to 60 ° C
Electrolytic treatment is carried out for 0 seconds, and an oxide film of 1 to 10 g / m ² is provided on the surface. Further, the current density at this time is 1 to 20.
A / dm ² is preferred. 5 to 50 in the case of the phosphoric acid method
% Concentration 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 .

As described above, after the anodic oxide film is provided, a post-treatment can be performed if necessary. For example, a method of dipping treatment in an aqueous solution of polyvinylphosphonic acid disclosed in British Patent No. 1230447 and US Pat.
The method of immersing in an aqueous solution of an alkali metal silicate disclosed in Japanese Patent No. 181461 is used. It is also possible to provide an undercoat layer of a hydrophilic polymer, if necessary.
Selection is made according to the properties of the photosensitive material provided after that.

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

[I] o of the polyhydroxy polymer
-When providing a photosensitive layer containing a naphthoquinone diazide sulfonic acid ester and a novolac resin of a phenol / cresol mixture.

As the polyhydroxy polymer compound,
A polycondensation product of a phenol compound (eg, resorcinol, pyrogallol, etc.) and an aldehyde compound (eg, formalin, benzaldehyde, etc.) having an average molecular weight of 1,000 to 7,000 and having, for example, two or more hydroxy groups on the 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 preferable novolak resin is a novolak resin containing a phenol having a relatively high molecular weight, which is disclosed in JP-A-55-
Phenol-m-cresol-formaldehyde novolac resins disclosed in 57841 are preferred. Further, in order to form a visible image by exposure, o-naphthoquinonediazide-4-sulfonyl chloride, inorganic anion salt of p-diazophenylamine, trihalomethyloxadiazole compound, trihalomethyloxadiazole compound having a benzofuran ring, etc. A compound or the like that generates a Lewis acid by the above light is added. On the other hand, as a pigment,
Triphenylmethane dyes such as Victoria Blue BOH, Crystal Violet and Oil Blue are used.
As the solid content of the photosensitive composition comprising these components,
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 forming the anodized film, it is immersed in the alkali metal silicate bath disclosed in US Pat. No. 3,181,461. It is preferred to provide a photosensitive layer containing a PF ₆ salt or BF ₄ salt of a diazo resin, an organic salt of a diazo resin and a water-insoluble and lipophilic polymer compound having a hydroxyl group on the surface thus treated. When such a photosensitive layer is coated on the surface of the support according to the present invention, it is possible to obtain a photosensitive lithographic printing plate which is excellent in storage stability and visibility and is stable particularly under severe conditions such as high temperature and high humidity.

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

The hydroxyl group-containing polymer compound is a compound having a weight average molecular weight of 5000 to 500,000, for example,
(1) A copolymer of N- (4-hydroxyphenyl) acrylamide, N- (4-hydroxyphenyl) methacrylamide, N- (4-hydroxynaphthyl) methacrylamide and the like with another monomer, (2) o- , M- or p-hydroxystyrene and other monomers, and (3) o-, m- or p-hydroxyphenyl methacrylate and other monomers and other monomers.

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

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

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

(D) Acrylamide or methacrylamide such as acrylamide or 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.

(I) N-vinylpyrrolidone, N-vinylcarbazole, acrylonitrile, methacrylonitrile, etc. may be mentioned, and any other monomer may be used as long as it is copolymerizable with a monomer having an aromatic hydroxyl group.

The oil-soluble dye added to the photosensitive layer is
Victoria Pure Blue BOH, Crystal Violet, Victoria Blue, Methyl Violet, Oil Blue # 603 and the like are preferable. To form a photosensitive layer having these compositions, a fluorine-based surfactant, a nonionic surfactant, a plasticizer (for example, 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 to 2.
It is provided so as to be 5 g / m ² .

[III] In the case of providing a photosensitive layer made of a photopolymerizable photosensitive composition containing a polymer having a carboxylic acid residue or a carboxylic acid anhydride residue, an addition polymerizable unsaturated compound and a photopolymerization initiator.

In the case of a photopolymerizable photosensitive material, it is preferable to anodize the surface of the support grained in a hydrochloric acid bath 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 material containing a polymer having a carboxylic acid residue or a carboxylic acid anhydride residue, an addition polymerizable unsaturated compound and a photopolymerization initiator. A layer of the volatile composition is provided. Further, it can be used for a lithographic printing plate using an electrophotographic photoreceptor as disclosed in JP-A-60-107042.

The printing plate thus formed has good storage stability, and the exposed surface of the aluminum plate in the non-image area is hard to be contaminated with printing ink, and has good hydrophilicity for quickly removing the contaminated ink. And has a high adhesive force with the photosensitive layer.

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

[0062]

[Chemical 1]

(In the formula, R ₁ and R ₄ represent a hydrogen atom or an alkyl group, R ₃ represents a phenylene group or an alkylene group which may have a hydroxy group, R ₅ represents a hydrogen atom or a substituent. An optionally substituted alkyl group, R ₆ represents an alkyl group which may have a substituent, an allyl group, an aryl group or a cycloalkyl group, and n represents 0 or 1) Formula (A) includes acrylic acid, methacrylic acid, crotonic acid, vinyl benzoic acid, and the like, Formula (B) includes maleic acid, maleic acid monohydroxyalkyl ester, maleic acid monocyclohexyl ester, and the like. Examples of C) include maleic acid monoalkylamides and maleic acid monohydroxyalkylamides, and examples of formula (D) include maleic anhydride and itaconic anhydride. Is mentioned. A polymer having an average molecular weight of 1,000 to 100,000 is 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, undergoes addition polymerization in the three-dimensional directions with each other to cause insolubilization. It is a monomer having a bond. Examples thereof include unsaturated carboxylic acids, esters of unsaturated carboxylic acids with aliphatic polyhydroxy compounds, and esters of unsaturated carboxylic acids with aromatic polyhydroxy compounds.

The photopolymerization initiator is 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 prepared as described above.

[0067]

EXAMPLES The present invention will be specifically described below with reference to examples.

Example 1 No. 1 shown in Table 1 1-No. Melting and casting 14 alloys, chamfering on both sides, thickness 500 mm, width 1000 mm,
A slab having a length of 3500 mm was homogenized at 540 ° C., heated to 400 ° C., hot-rolled, cold-rolled, and continuously anneal furnace at 500 ° C. (without holding). After performing the intermediate annealing, finish cold rolling was performed at a plate thickness reduction rate of 80% to obtain an alloy plate having a thickness of 0.30 mm.

The alloy sheet thus obtained was examined for mechanical properties. In addition, a single element of Si can be observed with a transmission electron microscope (TEM).
Was checked for.

Then, the surface of the alloy plate having a thickness of 0.30 mm was roughened with a rotating nylon brush in a suspension of pumice and water, and chemically etched with a 10% aqueous sodium hydroxide solution. Neutralized and washed in 20% nitric acid at a temperature of 20 ° C. and a current density of 30 A / d with a 1.5% nitric acid electrolytic solution.
AC electrolysis was carried out at m ² of 50 ° C. for 10 seconds. In addition, the time from the solution immersion to the energization during electrolysis was 3 seconds.

Subsequently, the surface was cleaned by immersing it in an aqueous solution of 15% sulfuric acid at 50 ° C. for 3 minutes, and then an oxide film of 3 g / dm ² was formed at a bath temperature of 30 ° C. in an electrolytic solution containing 20% sulfuric acid as a main component. Provided.

Thus prepared sample was provided with the following photosensitive layer so that the coating amount when dried was 2.5 g / m ² .

Ester compound of naphthoquinone (1,2) -diazide- (2) -5-sulfonic acid chloride and resorcin-benzaldehyde resin 1 part by weight Phenol and m-, p-mixed cresol and formaldehyde copolycondensation resin 3. 5 parts by weight 2-trichloromethyl-5- [β- (2′-benzofuryl) vinyl] -1,3,4-oxadiazole 0.03 parts by weight Victoria Pure Blue BOH (Hodogaya Chemical Co., Ltd.) 0.1 parts by weight p-Butylphenol benzaldehyde novolac resin o-naphthoquinonediazide sulfonate 0.05 part by weight Methyl cellosolve 27 parts by weight Using a 3 KW metal halide lamp, exposed at a distance of 1 m for 50 seconds, and then exposed to 4% sodium metasilicate aqueous solution for 25 seconds. Develop at 45 ℃ for 45 seconds, wash and dry After that, gumming was performed to obtain a lithographic printing plate.

After observing streaks (streak patterns) on the surface of the printing plate, these printing plates were mounted on an offset printing machine KOR, and stains (ink stains) on non-image areas and printing durability (until the printed matter became unclear) (Represented by the number of prints).
The surface of the pit pattern formed by electrochemical graining was observed with an electron microscope (SEM).

The above results are shown in Table 2.

Inventive Example No. In the case of 1 to 7, the tensile strength was as high as 136 MPa or more, simple substance Si was not observed, and the ink stain was extremely small. Further, the pit pattern is fine and uniform, and the number of printed sheets is as large as 100,000 to 110,000 so that the printing durability is good and there are no streaks.

Comparative Example No. In No. 8, since Fe is small, the strength is low, the pit pattern is slightly defective, and the number of printed sheets is small. No. No. 9 has a large pit pattern because of a large amount of Fe, and the number of printed sheets is small. No. No. 10 has a low strength due to a small amount of Si, the pit pattern is somewhat defective, and the number of printed sheets is small. No. Since No. 11 has a large amount of Si, it has a large amount of Si alone and has a large amount of ink contamination. No. 12 is Mg
Since it does not contain the formula (1) and does not satisfy the formula (1), it contains a little amount of Si as a single substance and a lot of ink stains. No. In No. 13, since the amount of Mg is large, the pit pattern becomes too fine and the number of printed sheets is small.
No. Since No. 14 does not contain Ti, streaks occur. No. In No. 15, since the amount of Ti is large, the pit pattern becomes non-uniform, and the number of printed sheets is small. No. 16 is Cu
However, the number of printed sheets is small due to lack of local etching. No. In No. 17, since the Mn is large, the pit pattern becomes non-uniform and the number of printed sheets is small. No. 18 is (Mg
%) − (Cu%)} ≧ −0.01 is not satisfied, so local etching shortage occurs and the number of printed sheets is small.

Example 2 No. 1 in Table 1 A plate having a thickness of 0.30 mm was obtained in the same process as in Example 1 for the alloys 2, 3, 4, 11, and 12. However, here, the temperature of the intermediate annealing was changed in the range of 420 to 540 ° C. The obtained alloy plate was subjected to the same treatment as in Example 1 to obtain a printing plate, and offset printing was performed to examine the ink stain resistance.

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. Inventive alloy No. 2,
In the case of Nos. 3 and 4, comparative alloy No. Compared with Nos. 11 and 12, the ink stain resistance is good at a considerably low temperature. Further, A ≧ 0 T ≧ −300A + 460 where A = 10 {2 (Mg%) + (Mn%)} − (Si
%) Shows good ink stain resistance.

[0080]

[Table 1]

[0081]

[Table 2]

[0082]

[Table 3]

[0083]

As described above, according to the alloy of the present invention, simple Si is melted and ink stains are caused without increasing the temperature of the intermediate annealing, that is, without reducing the stripping speed to reduce the efficiency. The problem of can be solved.

Furthermore, even if the processing conditions change, good electrochemical graining can be performed, and the restrictions on the processing conditions are greatly reduced.

As described above, according to the present invention, a great economic effect and energy saving effect can be achieved.

[Brief description of drawings]

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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kaido Kido 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries, Ltd. (72) Inventor Yoshinori Hotta 4,000 Kawajiri, Yoshida-cho, Haibara-gun, Shizuoka Prefecture Fuji In Shasha Film Co., Ltd. (72) Hirokazu Sakaki, 4000 Kawajiri, Yoshida Town, Haibara-gun, Shizuoka Prefecture Fuji Shashin Film Co., Ltd.

Claims (2)

[Claims] 1. Fe: 0.1 to 1.0% (weight basis, the same applies below) Si: 0.03 to 0.30% Mg: 0.002% or more and less than 0.05% Ti: 0.1 % Or less Cu: 0.020% or less Residual Al and inevitable impurities, and the content of Mn as impurities is 0.0
An aluminum alloy for a lithographic printing plate which is less than 5% and satisfies the following formulas (1) and (2). 10 {2 (Mg%) + (Mn%)} ≧ (Si%) …… (1) (Mg%) − (Cu%) ≧ −0.01 ……………… (2) 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 Cu: 0.020 % Or less The balance consists of Al and unavoidable impurities, and the content of Mn as impurities is 0.0
After less than 5%, the ingot of the alloy satisfying the following formulas (1) and (2) is homogenized, hot-rolled, cold-rolled, and then
A method for producing an aluminum alloy for a lithographic printing plate, which comprises performing intermediate annealing in a continuous annealing furnace at a temperature satisfying the expression (3), recrystallization, and then final cold rolling. 10 {2 (Mg%) + (Mn%)} ≧ (Si%) …… (1) (Mg%) − (Cu%) ≧ −0.01 ……………… (2) T ≧ − 300A + 460 ………………………… (3) However, in the above formula (3), T: intermediate annealing temperature (° C.) A = 10 {2 (Mg%) + (Mn%)}- (Si%).