JPS5967349A - Aluminum strip for photosensitive lithographic printing plate - Google Patents

Abstract

PURPOSE:To provide an Al strip for a photosensitive lithographic printing plate having an excellent electrolytic roughening property and the resistance to softening by burning by subjecting an Al alloy contg. relatively less Fe and Si to an intermediate annealing treatment and final cold rolling and specifying conductivity and yield strength. CONSTITUTION:An Al alloy contg. 0.2-0.4wt% Fe, 0.05-0.25wt% Si and the balance Al with impurities is subjected to an intermediate annealing treatment and final cold rolling. More specifically, the deposition of the intermetallic compd. of Al-Fe-Si or the like obtd. by an adeguate production method from the above-described Al alloy casting ingot is suppressed and the ingot is cold- rolled after recrystallization. The conductivity of such cold-rolled plate is 50- 60.5% JACS in a 0.275-0.6% (Fe+1.5XSi) range and 55-60.0% JACS in a 0.6-0.775% (Fe+1.5Si) range. The cold-rolled steel plate has the characteristics of >=1.3kg/mm.<2> yield strength, and provides the titled Al strip having <=20% rate of decrease in the yield strength when the strip is subjected to a heat treatment at a prescribed temp.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an aluminum plate strip for sensitive lithographic printing plates, namely:
Regarding an aluminum plate strip for a photosensitive lithographic printing plate having excellent electrolytic properties and 1) softening properties,
More specifically, it has a tit surface with excellent hydrophilicity and water retention, good adhesion with the photosensitive layer, and excellent printing durability. This invention relates to an aluminum plate strip for photosensitive lithographic printing plates that exhibits very little softening even after treatment and is excellent in handling properties.

Conventionally, an aluminum plate used as a support for a photosensitive plain printing plate is exposed to dampening water during printing.
In order to improve hydrophilicity, water retention, and adhesion with the photosensitive layer provided on the JJ, roughening is performed using mechanical polishing, chemical processing/etching, electrolytic roughening, etc. It is used after being surfaced (grained).

Surface shape of grained aluminum plate (grained shape)
The contribution to the plate-making performance and printing performance as a printing plate is extremely important, and it is extremely important to form the shape by F-rolling.

For example, sheet weight 1 requires good image reproducibility and resolution.
Printing of Shigen 1j: Relatively fine as an anti-supporting tree,
Shapes with shallow pits (bits) or dense sand are suitable. -Books that require force, water retention, and high printing durability (for books that support hole printing clothes, the focus shuttles are evenly aligned (microscopically uniform) and deep sand 1
1 shape is suitable.

Among the sand methods, the electrolytic polishing method is the defeatist polishing method (
Compared to chemical etching methods (ball polishing, -7 rasp, etc.) and chemical etching methods, it is possible to create anything from a relatively fine and shallow sand shape to a deep and uniform grain shape.

Generally, in the electrolytic surface roughening method, an aluminum plate is immersed in a suitable electrolyte solution and then subjected to alternating current or direct current electricity to perform 1) graining.

Hydrochloric acid and nitric acid are the most well-known as electrolytes, and when the electrolyte contains hydrochloric acid, the focus diameter is relatively thick and deep. A rough surface with a bit structure was obtained, and when the surface was electrolyzed in an electrolytic solution containing nitric acid, a rough surface with a pin-hole-shaped pin structure with a relatively small and deep diameter (via) was obtained. You can get some face.

However, it is conventionally used. JISAAl 1
(1(+, A 1 (,150 etc.) -
1- Electrolytic surface roughening treatment as described above (if this is used, 1t,
The surface of the plate is uneven in bit shape, has areas with excessive etching, and has the disadvantage of creating a rough surface that is undesirable as a printing plate and reducing printing durability. .

In order to improve the printing durability of the printing plate, after development, the printing plate is usually
In some cases, the resin in the image area on the aluminum plate is thermally hardened by the burning process for 1 minute, but in general, with conventional photosensitive planographic printing plates using aluminum plates, the burning process causes a large degree of softening during handling. The plate may bend, causing inconvenience.

The inventors of the present invention, paying attention to the problems mentioned in item 1 above, conducted intensive studies focusing on aluminum materials, and found that they have relatively low Fe and Si contents, that is, Fe 0.2□=0
．． A1=1・c S obtained by an appropriate manufacturing method from an aluminum ingot containing 4% by weight, 0.05-0.25% by weight of Si, and the balance consisting of aluminum and impurities.
I IfJ, rate 55□ = (io, 5% lA
An aluminum 11 plate having the required strength of C3 is heated to 1'l.
A uniform river surface can be obtained by heating the surface once, and a photosensitive layer is formed on the exposed surface and after development. The present invention was completed based on the discovery that the desired Li value for printing plates could be achieved.

The aluminum plate strip for photosensitive 11'-plate printing according to the present invention contains 0.2 to 0.4% by weight of doe and 0.0!5% Si.
- An aluminum alloy with 0.25% by weight, the remainder being 0.25% by weight and impurities, which is subjected to intermediate annealing treatment and final cold rolling, and has an electrical conductivity of 1% by weight, 5 X S. i weight%1 is (1,
275-60.5% l to 56 in the range 0,6%
AC3, [Fe weight old issue 5X Si weight %1 is 0.
55-60.0% I in the range 6-0.775%
The electrolytic solution was subjected to electrolysis treatment in a hydrochloric acid-based or nitric acid-based electrolyte solution, which is characterized by having an AC8 power of 13 KB/+n+n2 or more, and then heated at a heating temperature of 250°C at 80°C.
It is an electric current that has a low F ratio of 20% or less when heat treated by holding it for 1 minute! This is an aluminum plate strip for photosensitive lithographic printing that has excellent 11-facetization properties and burning softening resistance.

Below, regarding the aluminum plate strip for photosensitive lithographic printing plates according to the present invention (hereinafter sometimes simply referred to as the aluminum plate strip of the present invention); i! 1', explain to tllll.

The components and ratios of the components contained in the aluminum plate strip of the present invention will be explained below.

Fe 002 = 0.4% by weight, Si 0.05%-0
, 25% by weight of Fe is contained in order to obtain appropriate strength as a paper (photosensitive lithographic printing) and an appropriate surface in the 11th surface, and less than 0.2% by weight of Fe. , Sin, 05% by weight or less than 11% has low strength and may cause problems in handling as a photosensitive lithographic printing plate during plate-making work, etc., and when subjected to burning treatment, the yield strength further deteriorates and it cannot be used. It became unbearable and Fe
.

Sl crystallizes in Al as an Al-Fe-8i system intermetallic compound during agglomeration, and then comes out as a similar system precipitate when heated during the plate manufacturing process. The size of the dispersed phase of the Fe
If the content exceeds 0.4% by weight, Sin, and 25% by weight, the strength will increase, but as mentioned above, the dispersed phase in No\1 will catch fire and %<< ), A-bar enching (Earthwork/Enching unevenness is likely to occur and it is not possible. Therefore, F'a, S1 containing enemy is F'eO,
2-0.4 flat ridge%, Si 0.05-0.25 double claw shape.

The impurities include Cu, N411, M8.7,
11, 'l゛1, Cr, etc. may be included, but 0(
1, MII, 1IViP, , Zn is permissible within the range included in industrial pure aluminum, but CLIo
, 2% by weight or less, 4110.05 double claw shape or less, MF,
There is no problem as long as it is 0.05% by weight or less, and 91. As a lump silk weaving refiner'
Although it may contain I-1, it tends to cause agglomeration of AI-Ti particles, so it is preferable to keep the Ti content below 0.05% by weight, or it may be even higher depending on the electrolytic surface roughening treatment. t
There are cases where this regulation is required1), in which case 'l'1 is 0.
．． It is desirable to suppress the Cr content to 0.01% by weight or less, and for the same reason as explained in '1'1, it is desirable to suppress the Cr content to 0.2% by weight or less.

Next, the aluminum plate strip of the present invention (A I
-1,' e -The most important thing to do is to suppress the precipitation of intermetallic compounds such as Si-based intermetallic compounds and to recrystallize them. 1q
The crystallized cold IE K aluminum plate strip has a conductivity of t3 (1.5%lAC3 or less), but by adjusting the Fe and Si content and processing strain, the conductivity can be adjusted to the following range. be.

1', Published by F e wt%, 5X S i wt%l=o,
56-60.5%18cs in the range of 275-0.6%, preferably 56-60.0%1ΔCS, 1, F e weight%, 5XSi heavy enemy%1=o, 6-0
．． 775, 55 to 60.0% IΔcs, preferably 55 to 59.7% IAC3.

Therefore, electrical conductivity is determined by the content and solid solution state of Fe, Si, etc., and the more 417 elements of intermetallic compounds such as Fe, Si, etc. )1.The grass becomes lower. General f￥)l+, Without limiting the manufacturing process, an aluminum plate with the good components and component ratios shown below can be subjected to normal intermediate batch annealing (e.g., ゛, 3 G +'l') during cold rolling. C1 (approximately 2 hours), precipitation progresses, and the electrical conductivity is 60.5 after final cold rolling.
・-62%■ Becomes 8C8. As a result, the softening during the burning process is a problem, and the bit shape obtained during the electrolytic surface roughening process tends to become uniform.
It is not preferred as an aluminum plate strip for photosensitive plain printing plates.

However, when the conductivity is 0.275%≦[Fe heavy electric%] + 1.51 Si weight%1<0.6%, 56.~60.0% lAC3
, 0,6% < [Fe weight% l+], 5 (Si weight% 1≦
At 0.775%, 55-59.7% lAC3 was applied to the aluminum plate in a process where precipitation was suppressed.
The softening during the burning process is small, and the pit shape obtained by the electrolytic surface roughening process becomes uniform.

In addition, the measurement of electrical conductivity is carried out in 1. J I S H(,15(-
) 5 (Volume resistivity and conductivity of non-ferrous metal H material 4υ1
This was done in accordance with the constant force method.

Furthermore, the aluminum plate strip of the present invention has a yield strength of 13 kg/+n.
This means that as a support for a photosensitive lithographic printing plate, it must ensure soil resistance against bending and durability against repeated stress during printing, but especially in the image area. When wax is used after being heat-cured by burning, the support softens, so it is necessary to maintain the support (IJIIT properties, handleability (rigidity) and durability of the book) during the burning process. According to the results of the experiments conducted by the present inventors, it was found that the yield strength of the burn-treated support was approximately 1 Kg/+n+n21, which satisfied the required characteristics. .to'
Recrystallized aluminum plates of various thicknesses are cold-rolled (processing starts from $30) by suppressing the precipitation of intermetallic compounds such as e and Si.
95%, plate thickness after rolling 0.1~0.5+n+n)L- to measure the yield strength.Furthermore, each cold-rolled aluminum plate was heat treated at a heating temperature of 250°C for a holding time of 8 minutes to measure the yield strength. Low yield strength 'U' rate after heat treatment is 20%1:),
It turned out that it fit within. From the results from the north, the yield strength before burning treatment is at least I 3 Kg/+n+n21
;The month is -. In addition, the required strength and thickness of the aluminum strip are determined by adjusting the processing rate of the final cold rolling.
I can do 4Nru and 2.

1: Monthly Theory 11 JI 1-The present invention will now be described in detail about the manufacturing method of the aluminium laminate and strip for photosensitive lithographic printing.

Control of the electrical conductivity of the aluminum sheet strip of the present invention, that is, control of the state of solid solution precipitation of Fe, Si, etc. in the Aluminum laminated 11 matrix, is achieved by homogenizing one lump of aluminum ramid in the composition and component ratio of the aluminum laminated sheet strip of the present invention. After going through processes such as hot rolling, cold rolling, and intermediate annealing, the final plate thickness is 0. i=0.
The entire process of processing 5 into an aluminum plate strip with a surface thickness (this is what should be done here).

In particular, the homogenization treatment conditions and intermediate annealing conditions are important, and have a large influence on the burning softening resistance and electrolytic oxidation properties of the aluminum plate strip for photosensitive planographic printing plates.

Homogenization section J] 1! In order to make the Fe and Si contents in the plate surface composition of aluminum with the listed components and component ratios exist in a preferable state, It is desirable to carry out the test at a temperature of –.

Intermediate annealing requires recrystallization at a temperature higher than 3C.Furthermore, in order to control the precipitation of Fe and Si, after recrystallization by rapid heating, A short-time annealing method of rapid cooling is preferred. To explain in a more Hyogo way, 3 (1'(', / +n i n -1x
It is preferable to use an intermediate annealing method in which the annealing is held in the temperature range of 350 to 1'C for a short period of time (within about 3 minutes) at a heating and cooling rate of 3511'C. Crystals cannot be expected, and if the temperature exceeds 600'C, no further effect can be expected, and it is economically wasteful. The holding time should be as short as possible in order to prevent the precipitation of Fe, Si, etc., and 30 minutes or less may be sufficient.
It is preferable to maintain the temperature at a high temperature for preferably 10 minutes or less. In addition, regarding the temperature increase and temperature decrease rates, Fe, S
In order to suppress the precipitation of i as much as possible, 30"C/ +n
It is desirable that
11 ↓ 1 - At least according to the cooling chisel 11 speed]
, 11.1' C or less, preferably + 1,1 o °
There is a need to cool it down to below C.

If the only issue is the strength after the burning process, it may be possible to directly manufacture the product without performing an intermediate annealing during cold rolling. However, since it is not crystallized, the electrolytic surface roughening property is poor, and there are no streaks along the rolling direction. The generation of patterns and excessive machining/nching result in uneven focus form and focus diameter distribution, and furthermore, the bending properties tend to deteriorate, making it unsuitable for use as a support for photosensitive lithographic printing plates.
1. There is a suitable guess.

The final cold working rate after intermediate annealing is 30 to 95% in order to obtain appropriate strength as a photosensitive planographic printing plate.
There is a required intake, preferably 5() to 90%
. If it is less than 30%, the strength necessary for a printing plate cannot be obtained, and if it exceeds 95%, the bending properties will be lowered and the yield strength after burning treatment will be significantly lowered.

Through the process-1- below, the aluminum plate strip of the present invention is made of Fe.
By suppressing the precipitation of , Si, etc., recrystallizing and cold rolling, the above-mentioned electrical conductivity and required strength can be obtained.

In addition, in the casting method used in the manufacturing method of the aluminum sheet strip of the present invention, although the normal semi-continuous casting method is sufficiently effective, it is also possible to reduce the wall thickness at the time of production and increase the cooling rate. This is more effective from the viewpoint of suppressing precipitation.

The thus obtained aluminum plate strip for photosensitive lithographic printing plates according to the present invention is then electrolytically roughened, but before this electrolytic surface roughening, the aluminum plate strip is degreased in accordance with a conventional method. For example, cleaning with solvent 1111 fat such as trichloride or thinner, emulsion degreasing with kerosene and triethanolamine, etc., and cleaning with a concentration of 1 to 100 ml is recommended.
Add to 10% caustic soda aqueous solution at 20-70°C for 5 seconds to 1
() minutes to remove dirt and natural oxide film that cannot be removed by degreasing alone. So 5
A method of immersing the material for 2 to 5 minutes, neutralizing the material after alkali etching, and removing the sumant can be mentioned.

Electrolysis of the aluminum plate after these cleaning treatments is carried out in an electrolytic solution containing mainly hydrochloric acid or nitric acid, and the concentration of hydrochloric acid is 3.5.-35 g/l, preferably 5. ; 悄) 8/1, nitric acid concentration 5-358/1,
Preferably it is 7 to 3 (1 B/l).

The temperature of this electrolytic solution is usually about 10~/l fl'(:), and the current density is appropriately selected depending on the desired Sunaguchi appearance, but is usually 20~201) A/chn2, preferably! −) 0 = I S fl A / den'
It is.

If electric 1'lil'oJ1 conversion is performed on such a strip (i), sand 11 with uniform pit diameters and good quality as a printing plate will be produced.

This electrolytic PIT coating method can be carried out either batchwise or continuously, but the continuous method involves, for example, passing an aluminum strip continuously through an electrolytic cell. = 1m
J: ') i-1'', twisted and electrolytically roughened aluminum plate strips are heated at room temperature to 80℃ according to conventional methods, if necessary.
After desmutting and then neutralizing by immersion in an aqueous alkali or acid solution for 1-5 minutes at °C, printing:
Provided for anti-use support books. The obtained aluminum Ryukaku Ikan face plate strip did not have the uneven pin F shape and pit diameter distribution due to excessive or insufficient etching, which was observed in the conventional electric M11 face plate using an aluminum plate, and it was suitable for photosensitive lithographic printing plates. A rough surface with a suitable pit structure is formed uniformly and in a short time. In addition, when providing a supporting book for printing IUi, it is not necessarily the case that anodization may be performed on an aluminum plate according to a conventional method. Specifically, a current density of 1 is used in an aqueous solution of sulfuric acid or phosphoric acid with a concentration of 10 to 50%.
~I fl A , /dm7 is used as an electronic angle, - and 1 are performed.

After this anodic oxidation, one more step is required (correspondingly, sealing or hydrophilic treatment may be performed using hot water, silicate, dichromate, acetate, hydrophilic polymer compound, etc.).

The support obtained by subjecting the aluminum plate strip of the present invention to the above-mentioned treatment, the photosensitive material to be applied is not particularly limited, and various well-known materials can be used. can do. For example, compositions consisting of a hydrophilic polymer and an azonium salt, an azo compound such as an azo phenylamine, a composition of a quinosine diaso compound and an alkali-soluble resin, and a composition comprising a quinosine diaso compound and an alkali-soluble resin,
Similarly, polymers whose constituent components are unsaturated carboxylic acids that cause electrification, such as cinnamic acid phenylene diacrylic acid,
When irradiated with actinic rays, 1) a compound that causes polymerization, a binder polymer, a silk cloth, and an azide ratio compound may be mentioned.

Particularly preferred are quinolinoazide compounds and alkaline ri
f melt・la: ! It is a composition with i fat.

These photosensitive materials are dissolved in a suitable solvent together with various well-known additives, and the aluminum strip of the present invention (
By applying this coating and drying it, a photosensitive planographic printing plate can be manufactured.

If an image is superimposed on this photosensitive lithographic printing plate and exposed and developed in the usual manner, it has excellent hydrophilicity and water retention, and the adhesion between the image area made of photosensitive material and the aluminum strip is extremely strong. A printing plate that is strong and has excellent printing durability can be obtained.

For printing plates, when the number of printing runs is large and higher printing durability is required, or when printing using special chemicals such as ultraviolet curing tLV ink, special T and second plates are recommended. In such cases, it is necessary to significantly increase the printing durability by 10%, and in such cases, a burning treatment (heating at high temperature) is a widely used method.

This burning process usually takes 2 (month) to 300 ” (:,
It is preferably carried out at 250 to 260'C for 3 to 1 minutes, preferably about +3 to 8 minutes. This hardens the resin that forms each ridge and line of the plate, and as a result, the abrasion resistance and chemical resistance of the printed area increases, greatly increasing printing durability. .

Generally, considering ease of handling and other factors, it is desirable for the strength of a photosensitive planographic printing plate to have a yield strength of 11 Kg/mm2 or more after burning treatment, as described above.

Photosensitive planographic printing plates using conventional aluminum plate strips are
The yield strength before the burning treatment is 13 to 18 Kg/mm2, which is sufficient strength as a photosensitive plain printing plate, but the burning treatment causes a large degree of softening, which causes trouble in handling.

The photosensitive lithographic printing plate using the aluminum plate strip of the present invention is
Even after the burning process, the degree of softening is extremely small and the handleability is good. Specifically, 2.5 (,1'
Comparing the yield strength before and after the 0.3 minute burning process, the stiffness of the conventional printing plate before the burning process is 1;) ~] 5
K 8/tn11゛, after processing 11K B/
m m 'l; ノ, F, and the reduction rate is ゛20-30%
The above is also 1 Mr. T')-, but in the case of the 1" L printed clothes used in the present invention's aluminium 11 strips, the stiffness before burning 11 is 13.~]5 Kg/nun2, as described above
1.1 K g/torn even after this burning process
The rate of reduction of υ at sea level is 15 to 18% L:J, which is not too low.

Therefore, the present invention (this aluminum plate strip for photosensitive lithographic printing plates) not only has superior electrolytic properties, but also
It has excellent burning and softening resistance, is extremely easy to handle, and has excellent workability.

Next, examples of aluminum plate strips for photosensitive lithographic printing plates according to the present invention will be described.

Examples Table 1 (aluminum sheet strips of the present invention) and Table 2 (comparative examples) show the components and component ratios of the aluminum sheet strips used, the sheet manufacturing conditions, the strength, the IS property, and the electrical conductivity.
In addition, the results of electrolytic finishing treatment and burning treatment using this aluminum strip are shown at the same time.

The conductivity is 1. J I 5t (05t:) 51 Volume resistivity and conductivity measuring method of non-ferrous metal materials".

In the burning process, each aluminum strip was etched under the conditions shown in the table to form an 11-sided electrolytic sheet (all using alternating current), and then anodized to form an oxide film of about 25 mg/den2. A photosensitive lithographic printing plate was prepared by coating a diazide-based photosensitive liquid, and after exposing and developing the plates using a porcelain type film, a surface treatment was performed and the heating temperature was set to 25 ( )°C3 for 8 minutes.
n++2) (13) and the rate of decrease (%) (A
-B/ΔX 1 (110) is shown in the table.

The cold rolling rate (%) indicates the working rate (%) in the final cold rolling process. In Examples 1.2.3o6 and 4 in Table 1 and Comparative Example 1.2 in Table 2, the processing rate (%) of the final cold rolling after intermediate annealing, and in Comparative Example 3 in Table 2, It shows the final cold rolling rate (%) after inter-rolling, and the working rate (%) is calculated from the plate thickness (C) immediately before final cold rolling and the plate thickness after rolling (1)), /CX l 00 >.

25 - As is clear from this f51 table and Table 2, fFe
Weight% l + I, 5 X l', 3 i single i
, %1≦0.06%1koj3 Example 1.2.3 of Table 1 in which precipitation was suppressed, recrystallized and cold rolled.
The aluminum plate strip of the present invention has an electrical conductivity of 60. (1% I
A CS l; J, lower, yield strength also I 3 K, B/
In+n" or more. Therefore, when the support of a photosensitive lithographic printing plate is subjected to electrolytic 11-sided treatment, a uniform etching surface is obtained, and even when these printing plates are subjected to burning treatment, the yield strength is 11 KF, / 1 page 2 or more”
There are two, and the yield strength is 1 ㎡ 118% 1υ.

Excellent electrolytic glue 11 metabolization properties and burning softening resistance for printing plates can be obtained. Similarly, [1·゛e amount % J + 1.5 The aluminum plate strip of the present invention has a conductivity of 59.7%TAC3 or less, and a yield strength of 13 Bi/1n.
ll12 or more, the electrolytic etching property is good, and even after burning treatment, the yield strength is 11 Kg/++un2 or more and the 1 degree T ratio is 18% or less, so it can be used as a printing plate. On the other hand, the aluminum plate strip of Comparative Example 1.2 in Table 2 has the same components and component ratios as Example 1.2 in Table 1, but has a large amount of mold precipitates, so the conductivity is low. Therefore, it is difficult to obtain a uniformly etched surface during electrolytic etching, and when subjected to burning treatment, it becomes considerably soft and the yield strength is less than 10KB/+n+n.
The proof stress 1 degree F ratio is also 30% or more, making it extremely difficult to handle as a printing plate. In addition, the aluminum plate strip of Comparative Example 3 in Table 2 has the same components and component ratios as Example 3 in Table 1, has an electrical conductivity of 60.0% I A CS, and has a yield strength after burning treatment of] 3 K871111112
However, the electrolytically etched surface is non-uniform.
), the rate of age 1 age 1 year decline is 20% after burning treatment.
υ, -H also tend to cause problems as a printing version. This means that it is necessary not only to suppress the precipitation of intermetallic compounds in the aluminum strip, that is, to lower the conductivity, but also to recrystallize it. And the first
By simultaneously recrystallizing and suppressing precipitates under the intermediate annealing treatment conditions shown in Example 3 in the table, it is possible to improve electrolytic etching properties and burning softening resistance as a photosensitive planographic printing plate by adding rinsing. It is.

As explained in detail, the aluminum plate strip for photosensitive lithographic printing according to the present invention has the structure described in 2. Compared to Aluminum 1, (1) Softening due to burning treatment is significantly improved.

(2) Even when electrolytic surface roughening treatment is performed, no streaks occur along the rolling direction.

(3) When electrolytic surface treatment is carried out using an alternating current in a hydrochloric acid or nitric acid M solution, a uniformly roughened surface is obtained with no partially unetched areas or excessively etched areas.

(4) Sufficient durability against bending processability and repeated stress during printing required for photosensitive planographic printing plates.
: I can be satisfied.

This has an excellent effect.

Claims (1)

[Claims] F e O,2= 0.4 t'JfL, %, S i
Aluminum alloy containing O,05.-0.25% by weight, balance l\1 and impurities, intermediate annealing treatment and final cold treatment)-1:. The electrical conductivity is LF'(! Kurumatsu% + 1,5XSi weight%1 is O, Z75
= 0.6% range, 56-60.5% IA
C3, t, Fe weight% + 1.5XSi heavy enemy% 1 is 0
．． 55-60.0% in the range of 6=0.775%
IAC8, yield strength 13K8/+nm2 or more
The yield strength decrease rate is 20% or less when the surface is subjected to a 1'lrl' surface roughening treatment in a hydrochloric acid-based or nitric acid-based electrolyte, and further heat treated at a heating temperature of 250'C for 18 minutes. An aluminum plate strip for a photosensitive lithographic printing plate having excellent electrolytic 11-hedralization property and 14-burning softening property.