JPH0717154A - Production of photosensitive lithographic plate - Google Patents

Abstract

PURPOSE:To prevent a curved deformation of an aluminum substrate caused by a roughening treatment by a method wherein in the production of a photosensitive lithographic plate provided with a photosensitive layer on only one surface of the aluminum substrate, both the surfaces of the substrate are mechanically roughened. CONSTITUTION:In a production process of a photosensitive lithographic plate provided with a photosensitive layer on one surface of an aluminum substrate, such as a pure aluminum or aluminum alloy plate, prior to forming of the photosensitive layer, a surface of the aluminum substrate to be provided with the photosensitive layer is uniformly and densely roughened in a grained form for ensuring the adhesion of the photosentive layer and an appropriate water retentivity. However, the aluminum substrate roughened at only one surface thereof tends to curve. Therefore, the other surface that is not to be provided with the photosensitive layer is also roughened. The other surface that is not to be provided with the photosensitive layer is roughened using globular particles as an abrasive to have a center line average roughness of Ra of 0.1-0.3mum.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a lithographic printing plate support and a method for producing the same. More specifically, the present invention relates to a rough plate made of an aluminum plate for a lithographic printing plate and having little deformation, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, aluminum or its alloy plate has been used as a support for printing plates, especially offset printing plates. The support has a proper adhesiveness with a photosensitive layer provided thereon. It is required to have water retention. For this purpose, the surface of the support is roughened so that it has uniform and fine grain. As the surface roughening method, a wire grain is obtained by rotating a roll-shaped metal wire or a nylon brush (Japanese Patent Laid-Open No. 53-53113).
No. 145701), a blast grain made by colliding a brush grain or an abrasive with the surface (Japanese Patent Laid-Open No. Sho 50).
-136101, JP-A-60-19593)
And the like, an electrochemical graining method called electrolytic graining, a chemical graining method, and a method in which these graining methods are combined (JP-A-54-6).
3902 gazette) etc. are proposed. The blasting grain is performed by colliding the abrasive with the surface.The sand blasting is performed by accelerating the abrasive such as sand against the surface of the treated material under dry condition, or the polishing liquid (slurry) in which the abrasive is dispersed in the liquid. There has been proposed a method of accelerating spraying by combining the compressed air and the high-pressure liquid inside or outside the nozzle.

Further, as a kind of mechanical surface roughening method, the present applicant has previously conducted a roughening process by pressurizing and spraying a polishing liquid in which an abrasive is uniformly dispersed in water without accompanying a carrier fluid at a relatively low pressure. A method of surface treatment was proposed.

[0004]

However, using these mechanical surface roughening methods, of the two surfaces of the lithographic printing plate support made of an aluminum plate, the surface on which the photosensitive layer is provided (hereinafter referred to as the support When only the surface is treated), the support undergoes a curved deformation with the convex surface, and if the deformation is significant, it will cause difficulties in the subsequent lithographic printing plate manufacturing process and printing process. In particular, it has been found that processing cannot be performed with an automated device or an automated process. The problem to be solved by the present invention is to provide a method of preventing a camber which occurs when only the surface of an aluminum support is mechanically roughened.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, the above-mentioned curved deformation is caused by performing mechanical roughening treatment not only on the front surface of the support but also on the back surface. The inventors have found that the above can be prevented and have reached the present invention. Therefore, the gist of the present invention is a method for producing a photosensitive lithographic printing plate having a photosensitive layer provided on only one surface of an aluminum support, wherein a support surface provided with a photosensitive layer and a support surface not provided with a photosensitive layer are machined. It is easily achieved by a method for producing a photosensitive lithographic printing plate which is characterized by performing a roughening treatment.

The present invention will be described in detail below. The aluminum plate applied to the present invention includes pure aluminum and aluminum alloy plate. Various materials can be used as the aluminum alloy plate, for example, silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth,
An alloy of a metal such as nickel and aluminum is used.

Prior to roughening the aluminum plate, it is preferable to remove rolling oil from the aluminum plate and clean the surface. The method is, for example, a solvent such as trichlene,
Examples thereof include a method using a surfactant and an alkali etching agent such as sodium hydroxide and potassium hydroxide. In addition, when degreasing treatment is performed with an alkali / etching agent, smut is generated on the support.
It is preferable to perform immersion treatment in sulfuric acid or the like.

Next, the surface of the aluminum plate on which the photosensitive layer is provided is roughened by a mechanical roughening method. The mechanical surface-roughening method is not limited, and the above-mentioned various methods can be adopted. Particularly, blast graining or brush graining is preferable, and the blast graining method is more preferable. The abrasive injection pressure from the nozzle of the blast graining method is generally in the range of 1 to ²⁰ kg / cm ² G with respect to the surface of the aluminum plate, and preferably 2 to 10 kg.
/ Cm ² G. The abrasive concentration in the blast graining method is generally in the range of 5 to 70%, preferably 10 to 50%.

As the blast graining method, a method in which a polishing liquid (slurry liquid) in which an abrasive material is dispersed is combined with a carrier fluid such as compressed air or a high-pressure liquid in the nozzle or outside to accelerate spraying, There is a method of pressurizing the polishing liquid in which the polishing material is uniformly dispersed in water and directly injecting only the polishing liquid directly from the nozzle without entraining other carrier fluid, but graining even if the pressure is low The latter method, in which only the polishing liquid is sprayed under pressure, is preferable.

The roughening treatment device is not particularly limited as long as it can perform the above-mentioned treatment. For example, as shown in FIG. 1, a slurry stirring tank 1, a pressurized liquid feed pump 2, a liquid feed pipe 4, an injection nozzle 5 are provided. , A recovery tank (not shown), a recovery device (not shown) for recycling the liquid after injection into a predetermined liquid composition, and the like. The slurry agitation tank 1 stirs the slurry in a stirrer and a tank for stirring so that the abrasive, which is a solid content in the slurry, does not settle, that is, the abrasive is uniformly dispersed. It consists of a supply port for supplying. The stirring mechanism for preventing sedimentation of the abrasive and for making the slurry composition uniform is not limited, but may be a method of using a propeller inserted in the container, or a mechanism of circulating the slurry. Good. By constantly moving the slurry, sedimentation of the abrasive can be prevented. The pressurized liquid feed pump 2 takes out the slurry having a uniform composition in the slurry stirring tank 1 and feeds it to the injection nozzle 5 through the liquid feed pipe 4. The liquid contact part in the pump is sealed except for the supply port and the injection port, and the liquid contact part is made of a durable material such as ultra high molecular weight polyethylene (molecular weight of about 3 million to prevent abrasion of the pump due to slurry). .About.6 million).

The jet nozzle 5 may be one or plural,
In the case of a plurality of spray nozzles, it is preferable to provide them on the same pipe so that the pressure of the slurry sprayed from each spray nozzle becomes constant or reaches a desired pressure. In a general industrial production of a printing support, it is preferable that a surface which can be processed at the same time is large. Therefore, it is preferable to provide a plurality of jet nozzles. Further, since it is possible to share the piping for a plurality of injection nozzles with only one system of piping, the piping in the vicinity of the injection nozzle can have a simple form, and an arbitrary injection nozzle arrangement pattern can be adopted. It's easy. Furthermore, the spread angle of the nozzle holes may be adjusted arbitrarily.
Therefore, it is also possible to roughen a wide aluminum plate surface at once with a plurality of nozzles or to roughen the aluminum plate into an arbitrary pattern.

The aluminum plate may be, for example, but not limited to, placed on the conveying rotary roll 7 and sprayed with the slurry while being conveyed to be roughened. It is also possible to collect the slurry that has been sprayed from the spray nozzle 5 and has collided with the plate surface, and directly recycle it to a slurry stirring tank (not shown). In this way, since the slurry on the supply side and the slurry on the recovery side have the same composition, the slurry management becomes easy. In addition, since the particle size of the abrasive may change due to wear when the polishing liquid is used for a long time, a certain amount of the liquid is withdrawn from the slurry stirring tank, the abrasive with the changed particle size is collected, and the remainder and new polishing are performed. By incorporating a device (not shown) for feeding the material to the slurry agitation tank, it is possible to provide a device configuration that always provides a uniform slurry composition.

In order to obtain a proper Ra grain, it is desirable to optimize the grain size of the abrasive grains, the spray pressure of the slurry and the processing time as described below. When processing a continuous aluminum web, focusing on one point of the web,
The processing time at that point is represented by the following formula [II]. That is,
The processing time becomes longer by arranging a large number of nozzles to increase the number of times of spraying and slow down the traveling speed.

[0014]

[Equation 1] S = (W × n) / L S: Processing time of aluminum web (unit: second) W: Injection diameter from nozzle in web running direction (unit: m) n: Number of times nozzle ejection hits (unit: unit) : Time) L: Web running speed (unit: m / sec)

The injection pressure of the slurry from the nozzle is 1 to 2
It is generally selected from the range of 0 kg / cm ² G, and more preferably 1 to 10 kg / cm ² G. When the pressure is lower than this, the Ra may be lower than the desired Ra in some cases, and even when the desired Ra is obtained, a long-time operation may be required. In case of high pressure,
Ra is too large, the image reproducibility of the printing characteristics may be deteriorated, and the apparatus may be worn or the processing surface may be deformed. In other words, it becomes possible to use a pump having a considerably lower pressure than that conventionally required for pressurizing the slurry, and wear of the nozzles and the like can be considerably reduced as compared with the conventional case.

Further, it is preferable that the nozzle is made of a material durable to the slurry, for example, an ultra high molecular weight polyethylene having a molecular weight of about 3 to 8 million. The composition of the slurry liquid is a liquid such as water and usually fine powder of an abrasive. The abrasive is not particularly limited, and examples thereof include diamond, quartz, flint, granite, alundum, sacrundum, silica, pumice, silicon carbide, sand, and the like, but alumina such as alundum and sacrundum is preferred. Is.

Although the optimum range of the particle size of the abrasive varies depending on the desired roughness, it is usually JIS # 20 to 4000, preferably # 100 to # 500. Further, since the weight of the particles changes with the cube of the particle diameter, and the roughening effect is proportional to the weight of the particles, when an abrasive having a large particle diameter is used,
Ra increases synergistically. The center line average roughness Ra of the surface of the aluminum support is generally roughened to about 0.3 to 0.8.

Generally, the magnitude of the curved deformation is, as schematically shown in FIG. 2, a ratio of the rising height (H) of the central portion to the length (L) of the aluminum plate installed on the horizontal plate (hereinafter H / L) and H / L depend on the degree of deformation of the support such as the thickness and material of the aluminum plate, and the degree of processing in the roughening process, that is, the abrasive discharge pressure and the polishing. It also depends on the machining energy such as material grain size, brush rotation speed, brush pressing pressure, and other mechanical roughening devices and the material used.

That is, by mechanical roughening, for example, Ra
H / L when a large roughening index such as
Also grows. That is, H / L depends on the target roughness. With respect to this problem, the present invention has found that the curved deformation can be eliminated by subjecting the back surface of the surface subjected to mechanical roughening to mechanical surface processing. The mechanical surface roughening treatment for erasing the deformation is not particularly limited, but it is preferably blast graining or brush graining similar to the mechanical surface roughening treatment of the support surface,
Blast graining is particularly preferable.

Further, Ra on the surface of the support is usually larger than 0.3, and if the back surface of the support is roughened to the same degree,
The transportability of the printing plate may decrease. Therefore, from the viewpoint of appearance and transportability as a printing plate, the back surface of the aluminum support should be roughened so as to have some gloss even after mechanical roughening. Specifically, the back surface of the aluminum support is the center. It is particularly preferable that the surface is roughened so that the line average roughness Ra is about 0.1 to 0.3 μm.

A particularly preferred mechanical surface roughening method is a surface roughening method using an abrasive having a smooth spherical surface described below. FIG. 3 is a copy of a scanning electron micrograph of glass beads which is an example of an abrasive having a smooth spherical surface, and FIG. 4 is an example of an abrasive # WA # which is an example of an abrasive for suitably roughening the surface of a support. 180 is a copy of a scanning electron microscope photograph (manufactured by Japan Polishing Industry Co., Ltd.). The polishing material having a smooth surface as shown in FIG. The roughening effect is not so large as compared with the abrasive having a top portion used for roughening, but it has an effect of forming a plastically deformed layer on the back surface of aluminum. This layer eliminates the bending deformations caused by mechanically roughening the surface, while still maintaining the smoothness of the back surface and allowing the back surface to be glossy.

The spherical abrasive having a smooth surface may be made of any material, but glass beads are preferred because they are difficult to damage aluminum when the abrasive is crushed. The equipment for mechanical surface treatment using glass beads may be the same as the apparatus used for mechanically roughening the surface, for example, using a polishing liquid in which glass beads are uniformly dispersed in water,
The method of pressurizing and spraying only this polishing liquid to the back surface of aluminum through a nozzle at a polishing pressure of 1 to 20 kg / cm ² G, preferably 1 to 10 kg / cm ² G is most effective and preferable. The particle size of the glass beads used is JIS # 20-
4000 is preferably JIS # 100 to 500.

The above treatment may be carried out at the same time as the mechanical roughening step of the surface of the aluminum support, but since the material, particle size and the like of the abrasive used for the mechanical roughening are mixed,
It is desirable to carry out before or after the mechanical roughening treatment of the aluminum support surface. In the case of performing it later, it is more preferable because the abrasive used for the mechanical roughening treatment of the surface of the aluminum support performed before that also has an effect of removing it when it remains around the back surface of the support.

The surface of the roughened aluminum plate is then preferably chemically treated. This step is effective in removing abrasives and the like remaining on the surface formed by the roughening treatment. As a method of chemically treating, a known method such as a method of immersing in an acid that dissolves aluminum or an aqueous alkali solution can be applied. In the surface roughening method of the present invention, the amount of the abrasive material remaining on the surface is much smaller than that in the conventional surface roughening method, and this treatment is performed under relatively weak conditions, specifically 1 to 5 g / m ² as the amount of aluminum dissolved. It is possible to process under the processing conditions in the range.

When the amount of aluminum dissolved is 1 g / m ² or less, R obtained by mechanical roughening is obtained.
Although a is not impaired, stains may occur at the time of printing, and at 5 g / m ² or more, Ra obtained by mechanical roughening is impaired, and printing performance, particularly printing durability is deteriorated. However, a large amount of dissolved aluminum may be generated and the waste liquid treatment may be complicated.

The chemical treatment conditions can be defined by the amount of aluminum dissolved as described above, but can also be defined by the amount of increase in Ra. The amount of increase is generally 2 to 20% of Ra obtained by mechanical surface roughening. In this treatment, it is particularly preferable to use an alkaline aqueous solution. This is because alkali has a higher dissolution rate of aluminum and is more efficient than acid. Further, since smut is generated on the support when treated with alkali, it is preferable to remove the smut by immersing it in nitric acid, sulfuric acid or the like.

The chemically treated aluminum plate is then preferably electrochemically roughened. A conventionally known method is used for electrochemical surface roughening,
As the electrolytic solution, an aluminum plate is subjected to AC electrolysis in an electrolytic solution containing ions that attack aluminum.
More specific electrolytic solutions include hydrochloric acid, nitric acid, those containing additives to these, mixed acids and the like, and the concentration thereof is generally selected from the range of 0.5 to 5% by weight. As the AC power supply, conventionally known ones are used, but sinusoidal single-phase and three-phase AC are preferably used.

When electrochemical graining is added to mechanical graining, the mechanical graining must be performed in consideration of Ra increased by the latter. Further, it is preferable to carry out a chemical treatment after the electrochemical graining treatment. The purpose is to remove smut and the like remaining on the surface formed by the electrochemical graining treatment. As the method for chemically treating, there is a method of immersing in an acid that dissolves aluminum, or an alkaline aqueous solution, and the like, and it can be performed in the same manner as the case of the chemical treatment after the mechanical surface roughening treatment described above. it can. Further, when treated with alkali, smut is also generated due to this, so it is preferable to remove the smut by dipping it in nitric acid, sulfuric acid or the like.

The aluminum plate treated as described above is further subjected to anodizing treatment by electrolytic treatment in an aqueous solution of sulfuric acid, phosphoric acid or the like according to a conventional method, and then heat treatment for hydrophilization or inactivation as required. Water treatment, silicate, acetate,
Immersion treatment or the like in an aqueous solution containing a hydrophilic polymer compound can be performed. The aluminum plate thus obtained can be provided with a photosensitive layer according to a conventional method to obtain a photosensitive lithographic printing plate.

The photosensitive material of the photosensitive layer applied here is not particularly limited, and generally known materials can be applied, for example, a composition comprising a hydrophilic polymer and a diazonium salt, a quinonediazide compound and an alkali-soluble substance. A composition comprising a resin, an unsaturated carboxylic acid that doubles upon irradiation with actinic rays, such as cinnamic acid, a polymer having phenylenediacrylic acid as its constituent component, a compound that causes a polymerization reaction upon irradiation with actinic rays, and a binder polymer Examples thereof include a composition and an azide-based photosensitive composition.

[0031]

EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded.

<Example 1> A 1050 aluminum plate (thinning H24, 300 mm x 700 m) having a thickness of 0.3 mm
m) is immersed in an aqueous solution of sodium hydroxide for degreasing treatment,
Then, it was washed with water, immersed in an aqueous solution of sulfuric acid, and washed with water for pretreatment. Next, the surface of the aluminum was mechanically roughened under the following conditions using the slurry prepared as follows using the apparatus schematically shown in FIG.

[0033]

[Table 1]

After mixing the both, the mixture was stirred by a stirrer so that the abrasive was dispersed without settling. Under the following conditions, an aluminum plate was placed on a conveyor rotation roll, and the slurry was jetted while being conveyed to perform a roughening treatment.

[0035]

[Table 2] 2) Processing conditions a) Slurry injection pressure (pump pressure) 4 kg / c
m ² G b) Nozzle diameter 2 mm long, 4 mm wide oval c) Number of nozzles 24 (3 perpendicular to the processing direction. 8 rows in the processing direction) d) Nozzle hole spread angle 90 degrees e) Distance between nozzle and aluminum plate 90mm f) Processing time (time processed by jetting) 10 seconds

Next, glass beads (grain size JIS # 240)
Was used as the abrasive, and the back surface of the support was roughened in the same manner as the mechanical roughening of the surface of the support except that the treatment time was 2.5 seconds. In the present invention, the curved deformation amount H / L is measured by cutting out 200 mm from the central portion of the plate used to obtain L, and placing the mechanically roughened surface as the upper surface on a horizontal plate, and raising the height H I went in search of.

As a result, it was found that L / H was 0.001 or less and there was no problem in practical use. The H / L of the aluminum original fabric was 0.005 or less. 5 and 6 are photographs of the front and back surfaces of the mechanically roughened support, which are enlarged and photographed with an electron microscope, respectively. However, deep and three-dimensional unevenness was observed on the surface of the support (FIG. 6), and the surface shape was greatly different (FIG. 5). Furthermore, a stylus type roughness meter (SE3
When the centerline average roughness Ra was measured in C), Ra on the front surface was 0.52 and Ra on the back surface was 0.27. The back surface had the same gloss as before the mechanical roughening treatment, but the surface gloss was lost.

Comparative Example 1 H / L was measured in the same manner as in Example 1 except that the back surface of the aluminum support was not mechanically roughened. As a result, the H / L was 0.05, and the occurrence of remarkable curved deformation was observed.

Example 2 The grain size of the abrasive used for the mechanical roughening treatment of the back surface of the aluminum support was JIS 180 #.
Except that it is the same as in the first embodiment, and H
/ L and Ra of the back surface were measured. As a result, H / L is 0.
002 and Ra was 0.28, and a lithographic printing support having a smooth back surface was obtained without curving deformation.

Comparative Example 2 H / L was measured in the same manner as in Example 1 except that the mechanical roughening treatment of the back surface of the aluminum support was performed with 50 kg / cm ² G of water. . As a result, H / L of 0.05 showed no effect.

[0041]

EFFECT OF THE INVENTION According to the method for producing a support for a photosensitive lithographic printing plate of the present invention, a curved deformation which causes an adverse effect on the production process and printing caused by mechanical roughening of the surface of an aluminum support is effective. A photosensitive lithographic printing plate support erased in a.

[Brief description of drawings]

FIG. 1 is a schematic view of a mechanical surface roughening device used in the present invention.

FIG. 2 is a schematic view of a method for measuring the camber size.

FIG. 3 is a scanning electron micrograph showing the particle structure of glass beads used in the present invention.

FIG. 4 is a view showing a scanning electron micrograph of a grain structure of abrasive grains (WA # 180 manufactured by Nippon Polishing Industry Co., Ltd.) used for mechanical surface roughening.

FIG. 5 is a scanning electron micrograph showing the metallographic structure of the surface of a mechanically roughened aluminum support.

FIG. 6 is a scanning electron micrograph showing the metal structure of the back surface of a mechanically processed aluminum support.

[Simple explanation of symbols]

 1 Slurry stirring tank 2 Pressurized liquid feeding pump 3 Roughening treatment device 4 Slurry piping 5 Nozzle 6 Aluminum plate 7 Transport roll

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshihiro Yoshida 14 Sunayama, Hasaki-cho, Kashima-gun, Ibaraki Mitsubishi Kasei Co., Ltd. Kashima factory

Claims (3)

[Claims] 1. A method for producing a photosensitive lithographic printing plate comprising a photosensitive layer provided on only one surface of an aluminum support, wherein a support surface having a photosensitive layer and a support surface having no photosensitive layer are mechanically roughened. A method for producing a photosensitive lithographic printing plate, which comprises treating. 2. The photosensitivity according to claim 1, wherein the surface of the support having no photosensitive layer is subjected to a mechanical surface roughening treatment so that the center line average roughness Ra of the support surface is 0.1 to 0.3 μm. Method of manufacturing a lithographic printing plate. 3. The method for producing a photosensitive lithographic printing plate as claimed in claim 1, wherein the surface of the support having no photosensitive layer is mechanically roughened by using spherical particles as an abrasive. .