JPH079775A - Method for producing support for lithographic printing plate - Google Patents

Abstract

(57) [Summary] [Structure] A method for producing a lithographic printing plate support, comprising a roughening step of pressurizing and spraying a polishing liquid containing at least an abrasive onto an aluminum support, the method comprising the steps of: A method for producing a lithographic printing plate support, characterized in that the conditions of the step of converting are selected so that the following relational expression [I] is satisfied. [Equation 1] Ra = k * P ^0.5 * (100 / R) ² * (T / 10) ^0.1 +0.125 ... [I] where P: polishing liquid injection pressure (kg / cm ² G) R: polishing Material grain size (grain size number defined in JIS R6001) T: polishing time (sec) Ra: center line average roughness (μm) of rough surface of aluminum support obtained by roughening k: 0.38 ≦ k ≦ 0 as a constant .42 [Effect] It is possible to easily control the three values of P, R, and T to obtain a lithographic printing plate having an appropriate Ra.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a lithographic printing plate support. Specifically, it relates to a method for producing a rough surface plate made of an aluminum plate for a lithographic printing plate.

[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, sand blasting is performed by accelerating the abrasive such as sand against the surface of the treated material under dry conditions, or a polishing liquid (slurry) in which the abrasive is dispersed in a 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.

[0003]

However, in order to obtain a suitable grain as a support for lithographic printing by mechanical roughening with a slurry, the slurry concentration, slurry injection pressure,
It is necessary to precisely select and control various conditions such as abrasive material type, abrasive material particle size, and processing time. Further, as a support for lithographic printing, generally, the center line average roughness (JIS B0
601, hereinafter, abbreviated as Ra) is used to have a grain size of about 0.3 to 0.8, but if Ra is larger than this, image reproducibility may deteriorate, while Ra is larger than the above range. If it is too small, printing durability may decrease. In order to accurately produce a grain in the required range of Ra, an appropriate condition and range must be selected from many control factors for mechanical surface roughening, and it takes a lot of time and time. I need labor.

[0004]

Means for Solving the Problems The inventors of the present invention have earnestly studied to solve the above problems and obtain an excellent method for producing a lithographic printing plate support, and as a result, it is one of the indexes of the roughening treatment. Focusing on the center line average roughness Ra, a new relational expression [I] for calculating Ra is newly derived, and further, the relational expression [I]
Polishing coefficient k which is a proportional coefficient in 0.38 to 0.4
If 2 is selected, two of the three values of injection pressure P (kg / cm ² G), abrasive grain size R (grain size number defined in JIS R6001), and polishing time T (seconds) will remain and remain. We have found that a suitable range of one value is very easily calculated and arrived at the present invention.

That is, an object of the present invention is to easily control the three values of P, R and T in the surface roughening treatment using a slurry liquid so that the rough surface of a lithographic printing plate having an appropriate Ra value can be obtained. It is to provide a method of computerization. Thus, the object of the present invention is a method for producing a lithographic printing plate support having a roughening step of pressure-jetting a polishing liquid containing at least an abrasive onto an aluminum support, wherein A method for producing a support for a lithographic printing plate, characterized in that the conditions of the surface-imparting step are selected so that the following relational expression [I] is satisfied:

[0006]

[Formula 3] Ra = k * P ^0.5 * (100 / R) ² * (T / 10) ^0.1 +0.125 ... [I] where P: polishing liquid injection pressure (kg / cm ² G) R: polishing Material grain size (grain size number defined in JIS R6001) T: polishing time (sec) Ra: center line average roughness (μm) of rough surface of aluminum support obtained by roughening k: 0.38 ≦ k ≦ 0 as a constant .42

Alternatively, there is provided a method for producing a lithographic printing plate support comprising a roughening step of pressure-spraying a polishing liquid containing at least an abrasive on an aluminum support, wherein the roughening step is carried out. In the following relational expression [I], the center line average roughness Ra of the aluminum support is 0.3 to 0.8.
(Μm) so that the injection pressure P (kg / cm
² G), the abrasive grain size R (grain size number defined in JIS R6001), and the polishing time T (seconds), the polishing coefficient k in the relational expression [I] is set to 0.38 to 0. 42, two of the three values of P, R, and T are selected in advance and substituted into the relational expression [I], so that the remaining one of the three values of P, R, and T is A method for producing a lithographic printing plate support, which comprises calculating a range.

[0008]

## EQU4 ## Ra = k * P ^0.5 * (100 / R) ² * (T / 10) ^0.1 +0.125 ... [I] is easily achieved.

The present invention will be described in detail below. As the aluminum plate applied to the present invention, pure aluminum and
Aluminum alloy plates are included. Various aluminum alloy plates can be used, and for example, an alloy of aluminum with a metal such as silicon, copper, manganese, magnesium, chromium, zinc, lead, bismuth, or nickel is used.

Prior to roughening the aluminum plate, it is preferable to remove the rolling oil and clean the surface of the aluminum plate. Examples of the method include a method using a solvent such as trichlene, a surfactant, and an alkali etching agent such as sodium hydroxide and potassium hydroxide. Further, when degreasing is performed with an alkali / etching agent, smut is generated on the surface of the support. Therefore, it is preferable to immerse this in nitric acid, sulfuric acid or the like to remove the smut.

Next, the aluminum support is subjected to a surface roughening treatment, and the surface roughening step of the present invention includes a step of pressurizing and spraying a polishing liquid containing at least an abrasive. The step of pressurizing and spraying the polishing liquid of the present invention is not particularly limited, but the polishing liquid in which the polishing material is uniformly dispersed in water is pressed from the nozzle to the aluminum plate, and other carrier fluid is accompanied. Instead, it is preferable that the polishing liquid alone is directly pressurized and jetted from a nozzle so as to collide with the plate surface for graining and roughening the surface.

The roughening apparatus is not particularly limited as long as it can perform the above-mentioned treatment, but as shown in FIG. 1, for example, a slurry stirring tank 1, a pressurized liquid feed pump 2, a liquid feed pipe 4, an injection nozzle 5, and a recovery. It is composed of a tank (not shown), a recovery device (not shown) for recycling the liquid after injection into a predetermined liquid composition, and the like. The slurry stirring tank 1 includes a stirrer for stirring and a supply port for supplying the slurry into the tank so that the abrasive, which is a solid content in the slurry, does not settle, that is, the abrasive is uniformly dispersed. 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 a container, or a mechanism of circulating the slurry. . 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 wetted part inside the pump is sealed except for the supply port and the injection port,
Further, the liquid contact portion is preferably formed of a durable material such as ultra-high molecular weight polyethylene (molecular weight of about 3,000,000 to 6,000,000) or the like in order to prevent abrasion of the inside of the pump by the slurry.

The number of injection nozzles 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 the slurry may be jetted while being conveyed to be roughened. It is also possible to collect the slurry that has been injected from the injection nozzle 5 and has collided with the surface of the plate, 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 abrasive are removed. By incorporating a device (not shown) for feeding to the slurry agitation tank, it is possible to obtain a device configuration that always provides a uniform slurry composition.

However, in order to obtain a proper Ra grain, it is necessary to optimize the processing time in addition to the abrasive grain size and the slurry injection pressure described below. When processing a continuous aluminum web, when focusing on one point of the web, the processing time at that point is represented by the following formula [II]. In other words, arrange a large number of nozzles to increase the number of spray hits,
The processing time becomes longer by decreasing the traveling speed.

[0016]

[Equation 5] S: Processing time of aluminum web (unit: second) W: Jet diameter from nozzle in web running direction (unit: m) n: Number of hits from nozzle (unit: times) L: Web running speed (unit :) m / sec)

The injection pressure of the slurry from the nozzle is 1 to 2
0 kg / cm ² G, preferably 1 to 10 kg / cm ² G
Is. When the pressure is lower than this, the Ra may be too smaller than the desired Ra, and even when the desired Ra is obtained, long-time operation may be required. When the pressure is high, Ra may be too large and 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 pressure much lower than that conventionally required for pressurizing the slurry, and wear of the nozzle and the like can be considerably reduced as compared with the conventional one.

Further, it is preferable that the nozzle is made of a material durable to the slurry, for example, ultrahigh molecular weight polyethylene having a molecular weight of about 3,000,000 to 6,000,000. The composition of the slurry liquid is a liquid, for example, usually water and 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, 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. Therefore, when an abrasive having a large particle diameter is used, Ra increases synergistically. Ra suitable for lithographic printing support
Items to be controlled to obtain the injection pressure, treatment time,
Although it is the abrasive grain size, the inventors
When the effect and weight on a are examined and the center line average roughness Ra, which is an index of surface roughening, is expressed by the above relational expression [I],
3 so that the polishing coefficient k falls within the range of 0.38 to 0.42
It was found that the desired lithographic printing support can be obtained by controlling the factors.

According to the present invention, in the roughening step of the support for lithographic printing, for example, the grain size with respect to the target Ra,
When the processing time is determined, the required discharge pressure is calculated by the formula [I], and the swing width information of each factor is also obtained, which has an excellent aspect such as easy control. The surface of the aluminum plate roughened with the polishing liquid is preferably chemically treated next. 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.

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.
Also, when treated with alkali, smut is generated on the surface of the support, so dip it in nitric acid, sulfuric acid, etc.
It is preferable to remove the smut. When the amount of aluminum dissolved is 1 g / m ² or less, Ra obtained by mechanical surface roughening is not impaired, but stains may occur during printing, and when it is 5 g / m ² or more, mechanical strength is increased. Ra obtained by surface roughening may be impaired, printing performance, especially printing durability may be deteriorated, or a large amount of dissolved aluminum may be generated to complicate waste liquid treatment.

The chemically treated aluminum plate is then preferably subjected to an electrochemical graining treatment. 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. According to general electrochemical graining, Ra usually increases in the range of 0.05 to 0.2. 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 an anodizing treatment by electrolytic treatment in an aqueous solution of sulfuric acid, phosphoric acid or the like according to a conventional method, and then subjected to 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 dimerizes upon irradiation with actinic rays, for example, 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. And the azide-based photosensitive composition.

[0026]

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. <Examples 1 and 2 and Comparative Examples 1 and 2> 1 having a thickness of 0.3 mm
A 300 mm × 700 mm aluminum plate of 050 material was immersed in an aqueous solution of sodium hydroxide for degreasing treatment, then washed with water, immersed in an aqueous solution of sulfuric acid, and subjected to pretreatment of washing with water.

Next, using the apparatus schematically shown in FIG. 1, a mechanical roughening treatment was carried out under the following conditions with the three kinds of slurries prepared as follows.

[0028]

[Table 1] 1) Preparation of Slurry Volume Ratio Abrasives: White alundum with the particle size shown below 20 parts Slurry 1: JIS # 100 Slurry 2: JIS # 150 Slurry 3: JIS # 180 (all manufactured by Japan Abrasives Industry Co., Ltd. ) Water: 80 parts

After mixing 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.

In order to obtain the target Ra (0.40 μm), the injection pressure of the slurry and the treatment time were set to 2 kg / cm ^{2 in} Example 1.
20 sec for G, 20 kg for Example 2 at 4 kg / cm ² G
ec, Comparative Example 1 was 2 kg / cm ² for 10 seconds, Comparative Example 2 was 4 kg / cm ² G for 10 seconds, and the formula [I] was used to calculate the particle size range to be selected in each Example and Comparative Example. , The particle size was selected. As a result of the calculation, 145 to 152 were obtained in Example 1, so # 150 was selected and Slurry 2 was used for the experiment.

Since 173 to 182 were obtained in Example 2, # 180 was selected and Slurry 3 was used in the experiment. In Comparative Example 1, 140 to 147 were obtained,
Since there was no granularity in that range in the JIS standard,
# 150 was selected and Slurry 2 was used for the experiment. In Comparative Example 2, 166 to 175 were obtained, but since there was no particle size corresponding to that range in the JIS standard, # 180 was selected and Slurry 3 was used for the experiment.

Aluminum plates were roughened using the slurries selected under the conditions of Examples 1 and 2 and Comparative Examples 1 and 2, and Ra of the plates obtained under the respective conditions was measured by a stylus type manufactured by Kosaka Seisakusho. It measured with the roughness meter (SE30). The measurement result is
In Examples 1 and 2, Ra (0.41 μm) equivalent to the target was obtained. On the other hand, in each of Comparative Examples 1 and 2, an abrasive having a slightly higher level than the appropriate particle size (that is, the particle size was small) was selected, so that the target value of 0.37 μm could not be obtained.

<Example 3, Comparative Example 3> Target Ra (0.6
5 μm), the same aluminum plate and slurry 1 as used in Example 1 were used, the treatment time was set to 10 seconds, and the optimum slurry injection pressure range was calculated using the formula [I]. The calculation result is 1.6 kg / cm to 1.9 kg / c.
m ² G was obtained. Therefore, as Embodiment 3, the injection pressure is 1.7.
When the roughening treatment was performed at 5 kg / cm ² G, the target Ra of 0.65 μm could be obtained. On the other hand, as Comparative Example 3, Example 3 was repeated except that the injection pressure was set to 2 kg / cm ² G.
Roughening treatment was performed under the same conditions as
The value a was 0.70 μm, which was outside the target value.

[0034]

The support for a lithographic printing plate according to the production method of the present invention has the following characteristics. 1. Roughening conditions can be easily selected. 2. Since the factors that influence the surface roughening are expressed by the formula, the fluctuation range by each factor can be obtained, and the management of the manufacturing conditions is easy.

[Brief description of drawings]

FIG. 1 is a schematic view of a processing apparatus using a polishing liquid showing an embodiment of the present invention.

[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 lithographic printing plate support, comprising a roughening step of pressurizing and spraying a polishing liquid containing at least an abrasive onto an aluminum support, wherein the conditions of the roughening step are included. Is selected so that the following relational expression [I] is satisfied, and a method for producing a lithographic printing plate support. [Equation 1] Ra = k * P ^0.5 * (100 / R) ² * (T / 10) ^0.1 +0.125 ... [I] where P: polishing liquid injection pressure (kg / cm ² G) R: polishing Material grain size (grain size number defined in JIS R6001) T: polishing time (sec) Ra: center line average roughness (μm) of rough surface of aluminum support obtained by roughening k: 0.38 ≦ k ≦ 0 as a constant .42 2. The method for producing a lithographic printing plate support according to claim 1, wherein Ra is selected from the range of 0.3 to 0.8 μm. 3. A method for producing a lithographic printing plate support, comprising a roughening step of pressurizing and spraying a polishing liquid containing at least an abrasive on an aluminum support, wherein the roughening step comprises: In the following relational expression [I], the center line average roughness Ra of the aluminum support is 0.3 to 0.8.
(Μm) so that the injection pressure P (kg / cm
² G), abrasive grain size R (particle number defined in JIS R6001), and polishing time T (seconds), the polishing coefficient k in the relational expression [I] is set to 0.38 to 0.
42, two of the three values of P, R and T are selected in advance and substituted into the relational expression [I] to obtain P, R and T.
The method for producing a support for a lithographic printing plate, comprising calculating the range of the remaining one of the three values. [Equation 2] Ra = k * P ^0.5 * (100 / R) ² * (T / 10) ^0.1 +0.125 ... [I]