JPS6227191A - Production of base for planographic plate - Google Patents

Abstract

PURPOSE:To remove flash and corners of a primary grain by grinding and improve liability to contamination, which is a demerit of brush graining, by providing a primary grain by brush graining and then modifying the shape of the first grain by liquid honing. CONSTITUTION:An aluminum plate is mainly used as a metallic web for a base. An abrasive slurry liquid is applied to the aluminum plate being fed, and surface roughening is conducted between a support roll and a brush roll under a predetermined pressurizing condition. The abrasive slurry liquid is obtained by dispersing in water an abrasive ordinarily used. In a liquid honing device, the flow of a high-pressure liquid ejected from a nozzle is mixed with the flow of the slurry ejected from a ejecting port. The ejecting velocity is 31-140m/sec for the high-pressure liquid, and 2-25m/sec for the slurry. The slurry is constituted of water and a fine powder of the abrasive. The center line average roughness (Ra) after the modification of the grain shape is preferably about 0.3-1.2mum.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a support for a lithographic printing plate, and particularly to a method for roughening the surface of an aluminum plate as a support. .

[Conventional technology]

Conventionally, as a lithographic printing plate, a so-called PS plate (P
The aluminum plate is roughened by various methods, or after roughening, it is etched with an acid or alkali aqueous solution, and then subjected to anodizing treatment, and then, if desired, made hydrophilic. After being subjected to a chemical treatment, it is used as a support for lithographic printing plates. A photosensitive layer is provided on this support to form a photosensitive lithographic printing plate, that is, a PS plate, and this is subjected to processes such as exposure, development, correction, and gumming to form a printing plate, which is then attached to a printing machine. to print.

Examples of surface treatment methods for the aluminum plate described above include boulder grain, wire grain, brush grain,
Mechanical surface roughening methods such as liquid honing, electrochemical surface roughening methods called electrolytic graining, chemical surface roughening methods, and methods that combine these surface roughening methods are used. There is. However, these conventional methods each have the following problems.

In other words, in the case of Ball d'Arain, special care must be taken in selecting the type (material) and size of the balls used, adjusting the moisture during polishing, polishing time, and evaluating the finished surface because it is a batch process. There was a problem in that it required a lot of skill and the productivity was extremely low. In addition, in the case of wire grain, the grain of the resulting aluminum plate surface is uneven, and with brush grain, it is not possible to obtain a large roughness on the roughened surface, and the roughness is due to wear of the polishing brush used. Moreover, due to the strong friction between the bristles of the brush and the abrasive material, the aluminum surface is scratched in a complex manner, resulting in many sharp protrusions that are comparable to paris. Even during development, the photosensitive layer that should have been removed may remain on the plate surface, causing stains on the printing plate, and when handling the aluminum plate, the treated surface (rough surface) may be rubbed together, causing scratches on the surface. There was a problem.

In the case of liquid honing, a slurry liquid in which fine abrasive powder is dispersed in a liquid is blown at an accelerated rate using compressed air, so that the fine abrasive powder tends to stick to the aluminum surface, resulting in flaking. In addition, with this method, the impact force of the slurry liquid on the aluminum surface is weak, making it impossible to sufficiently increase the surface roughness.Furthermore, since the slurry liquid is ejected at an accelerated rate, there are problems such as significant wear of the ejection nozzle. . Furthermore, in electrochemical surface roughening, the electrolytic conditions must be precisely controlled in order to maintain a constant grain pattern on the roughened surface, which requires considerable power consumption, and also reduces the amount of residue remaining in the electrolyte. The treatment of waste liquid containing accumulated Aβ ions is very expensive, and in the case of chemical roughening, the treatment time is long, so it is not suitable for mass production, and as in the case of the above method, waste liquid Requires a large amount of processing costs,
It was not suitable for mass production.

[Problem that the invention seeks to solve]

As a surface roughening method that partially eliminates the drawbacks of each of the graining methods mentioned above, a composite surface roughening method using a brush grain method or a wire grain method and an electrolytic grain method is disclosed in U.S. Patent Nos. 2 and 3.
44,510, JP-A-53-123204, JP-A-53-145701, JP-A-54-6390
In addition to Japanese Patent Application Laid-Open No. 19593/1983, a composite surface roughening method using a liquid honing method and an electrolytic durrene method is disclosed. When the brush grain method is used as the mechanical graining method, which is the first step in this composite surface roughening method, stains are likely to occur during printing, and when the wire grain method is used, printing durability is poor. It had the disadvantage of being sufficient. In addition, when using the liquid honing method, although it is excellent in stain resistance, the printing durability is insufficient, and further improvements were necessary to satisfy the market's demand for even better quality. .

Therefore, an object of the present invention is to provide a method for producing a support for a lithographic printing plate that does not cause printing stains and has satisfactory stiffness resistance.

Another object of the present invention is to provide a method for producing a lithographic printing plate support that can stably form uniform grains and is suitable for large-scale production.

[Means for Solving Problem E] The present inventors focused on the performance of planographic printing plates affected by the differences in mechanical surface roughening methods in the above-mentioned composite surface roughening method, and as a result of intensive study, the brush It has been found that by forming primary grains by a grain method and then modifying the shape of the primary grains by a liquid honing method, a support for a lithographic printing plate that maintains excellent performance can be obtained.

The "liquid honing method" mentioned here is JP-A-59-2
No. 14697, JP-A-60-18390, JP-A-59
It is a method disclosed in Publication No. -229397 etc.
A method in which high-pressure liquid is ejected from a nozzle at high speed, this ejected stream is combined with a slurry containing fine abrasive powder ejected from another ejection port, and this combined material is collided with the surface of an aluminum plate to perform graining. be.

That is, the feature of the present invention is that first, by the brush grain method,
A primary grain with a short period, denseness, and excellent printing durability is formed, and then the shape of the primary grain formed by the brush grain method is modified using the liquid honing method described above, and the grain is By scraping away the edges and edges, the problem of easy staining, which is a drawback of the brush grain method, is improved, and a support for lithographic printing plates with poor performance can be obtained.

In the present invention, since the grain shape is modified mechanically by a liquid honing method, the amount of etching in alkali etching can be reduced compared to the conventional method, and therefore, the rigidity resistance is not significantly impaired.

Further, a second electrochemical treatment with a shorter period is further performed in an electrolyte of hydrochloric acid, nitric acid, or a combination thereof.
By superimposing the second grain to form a new composite roughened grain, the surface area on the aluminum surface can be expanded, and a support for a lithographic printing plate with even better printing durability and water retention can be produced.

The present invention will be explained in detail below.

In the present invention, an aluminum plate is mainly used as the metal web for the support, and the materials for the aluminum plate used include pure aluminum and aluminum alloys, and the latter include silicon, copper, iron, manganese,
There is an alloy whose main component is aluminum, which contains small amounts of magnesium, chromium, zinc, lead, bismuth, nickel, etc. In any case, it can be said that it is preferable that the purity of aluminum is 99.0% or more.

The roughening of the aluminum plate will be described in detail below, but the present invention is not limited to this, but can also be applied to other metal webs such as zinc and iron.

For planographic printing plates and 17, aluminum plates made of such materials are generally rectangular in shape due to printing presses, but in the present invention, until they are cut into rectangles, they are not particularly suitable for mass production. band-like (web-like) on the scale of
, and is handled by selecting it as appropriate. The thickness of the aluminum plate is practically 0.1 to 0.5, considering the tensile strength, yield strength, elongation, bending strength, etc. required when a lithographic printing plate made using the aluminum plate is adhered to a printing machine. n
It is appropriately selected within the range of +m.

The brush roll used in the brush grain method is a roll-shaped base in which brush materials such as nylon, polypropylene, animal hair, or steel wire are implanted with uniform hair length and hair flocking distribution. The diameter of the brush material is preferably selected within the range of 0.1 mm to 1.5 mm, and the length of the bristles after flocking is preferably within the range of 10 mm to 150 mm.

The rotation of the brush roll is preferably from 20 Orpm: 2
, 000 rpm. The support roll used has a rubber or metal surface and is well-maintained in straightness.

The abrasive slurry liquid is sprayed onto the aluminum plate being transported by a vehicle before passing through the brush roll.

The brush roll is pressed against the aluminum plate, and the surface is roughened under constant pressure conditions between the support roll and the brush roll.

The Kenreki slurry liquid used is diamond sand, silica sand, alumina powder,
A commonly used abrasive such as carborundum, pumice, zirconia, etc., preferably dispersed in water in a range of 10% by weight to 70% by weight is used.

On the other hand, the device for the liquid honing method for modifying the grain shape of brush grains described above consists of a nozzle connected to a high-pressure liquid supply section and an ejection port in contact with an abrasive slurry supply section, and the abrasive slurry is ejected from the nozzle. Both are arranged so that the flow of high-pressure liquid and the flow of slurry ejected from the ejection ports described later merge.

The number of the nozzles may be one or more. In the case of a plurality of nozzles, a plurality of nozzles may be provided around a jetting port described later.

The above-mentioned high-pressure liquid supply section is not only a container containing a liquid maintained at a high pressure, but also a system consisting of a container containing a liquid under normal pressure and a pressurized jet pump connected to the container. There are various aspects.

In either embodiment, it is necessary that the liquid be ejected from the nozzles connected to each one at a flow rate of 31 to 140 m/sec. The fluid pressure that causes this flow velocity is
5-100kg/cII! It is calculated as follows.

Further, the hydraulic pressure may contain acid or alkali as desired.

On the other hand, the Kenreki slurry supply section includes a container for storing the slurry, and preferably a stirring mechanism to prevent the solid content of the slurry from settling. The stirring mechanism for preventing sedimentation of solids may be a propeller-type stirrer installed in the container, or may be a mechanism for circulating the slurry. By constantly moving the slurry, settling of solids can be prevented.

A pipe, such as a pressure-resistant hose, extending from the container to the nozzle mentioned later extends to connect the two, and a liquid feed pump for spouting the slurry is provided in the middle of this connecting pipe. The Kenreki slurry supply section configured as described above sends slurry in an agitated state to a nozzle through a connecting pipe using a liquid feed pump, and jets out the slurry from the nozzle. The jetting speed of the slurry may be approximately 2 to 25 m/sec.

The composition of the slurry is water and fine powder of abrasive material, and the concentration of fine powder is about 5 to 80% (weight ratio).
An amount of about 50% is used.

An acid or alkali can be added to the slurry if desired. Diamond, crystal, flint,
Granite, alundum, silica, diatomaceous earth, sand, diamond sand, garnet, talc, pumice, dolomite, magnesium oxide, alumina, zirconia, SUS, iron powder, tungsten carbide, etc. are available, and the desired particle size, e.g.
#20 to #600 are used.

The high-pressure liquid flow accelerates the slurry flow and causes it to collide with the aluminum plate surface. In this case, the angle of collision with the aluminum plate surface is suitably in the range of 15° to 165°.

In this way, after primary grain formation by brush grains,
The center line average roughness (Ra) of the aluminum surface at the stage where the grain shape has been modified by liquid honing is preferably about 0.3 to 1.2 μm, more preferably,
It is 0.35-0.8 μm.

The support thus obtained is subjected to alkali etching, if necessary. This etching treatment is absolutely necessary if electrochemical graining, which will be described later, is to be done uniformly. In addition to alkali, etching may be performed using a solution that corrodes aluminum (for example, an acid such as hydrofluoric acid, phosphoric acid, or sulfuric acid). Preferred alkaline agents include caustic soda, caustic potash, sodium metasilicate, soda carbonate, sodium aluminate, and sodium gluconate. It is appropriate to select the concentration from 1 to 50%, the temperature from room temperature to 90°C, and the time from 5 seconds to 5 minutes, and the amount of aluminum etched is 0.
．． It is preferable to select it so that it may be in the range of 1-10 g/m'.

Since alkali-insoluble substances (smut) remain on the surface of the aluminum plate etched with alkali, acid solution (HNO3, 12SO, , H, PO4
Desmut treatment is performed using a solution (solution, etc.).

Subsequently, the surface of the aluminum plate is electrochemically roughened. The electrolytic solution at this time is preferably hydrochloric acid, nitric acid, or a mixture thereof. Electrolysis is carried out using direct current or alternating current in a solution of 0.1 to 10 wt%, more preferably 0.3 to 3 wt%. A secondary assembled surface is formed on the surface depending on the amount of electricity used for electrolysis. The pit depth of secondary grain is 0.1~1
More preferably, the bit depth is 0.1 to 0.811 and the pit diameter is 0.1 to 3 μ.

To form such a pit diameter. Special Public Service 1986-19
It is more preferable to use the special alternating waveform described in No. 280 and Japanese Patent Publication No. 55-19191. That is, by controlling the electrolytic waveform, secondary grains can be formed economically and uniformly. Also, US Patent No. 39635
Amine, gluconic acid, boric acid, phosphoric acid, hydrofluoric acid, etc., as disclosed in specifications such as No. 64 and No. 3980539, may be added to the electrolytic solution.

Preferably, the secondary grained aluminum is subsequently treated with an acid or alkaline solution.

Specifically, in addition to the phosphoric acid described in Japanese Patent Publication No. 56-1.1316, phosphoric acid or a mixture of phosphoric acid and chromic acid is used. Further, smut adhering to the surface is removed by lightly etching with an alkaline solution such as caustic soda as described in Japanese Patent Publication No. 4G-28123. When removing attached smut with an alkaline solution, the aluminum surface is etched, so alkali-insoluble components remain. Therefore, it is necessary to desmut again with an acidic solution (sulfuric acid, phosphoric acid, chromic acid, etc.).

In addition, after forming the primary grain with brush grains, the shape of the primary grain may be modified by liquid honing and then used as a support for a lithographic printing plate, but the diazo compound in the photosensitive layer is stable over time. An anodic oxide film may be formed on the intermediate layer or the aluminum surface in order to maintain properties or to improve adhesion with the photosensitive layer, rigidity resistance, etc. This treatment also applies to supports superimposed with electrochemical sand self-supporting.

The intermediate layer herein refers to a silicate layer obtained by dipping with an alkali metal silicate, for example, sodium silicate, as described in U.S. Pat. Nos. 2,714,066 and 3,181,461, or a hydrophilic undercoat layer. For example, it refers to an undercoat layer such as CMC or PVA.

In addition to sulfuric acid, examples of the electrolytic solution used to form the anodic oxide film include phosphoric acid, chromic acid, oxalic acid, and benzenesulfonic acid.

The anodic oxide film is preferably formed on the surface with a thickness of 0.81 to 10 g/m', more preferably 0.3 to 5 g/m'.

It is preferable to perform alkali etching and desmutting treatment before anodizing.

The conditions for anodic oxidation vary depending on the electrolyte used, so they cannot be determined unconditionally, but generally, the concentration of the electrolyte is 1 to 80% by weight, the temperature is 5 to 70°C, and the current density is 0. Appropriate ranges are 5 to 60 A/dm', voltage 1 to 100 cm, and electrolysis time 10 seconds to 5 minutes.

The grained aluminum plate with the anodic oxide film obtained in this way is itself stable and has excellent hydrophilic properties, so a photosensitive coating can be immediately applied on top, but if necessary, the surface can be further coated. Can be processed. For example, a silicate layer made of the alkali metal silicate described above or an undercoat layer made of a hydrophilic polymer compound can be provided.

The coating amount of the undercoat layer is preferably 5 to 150 μ/m'.

Next, a photosensitive coating film is provided on the aluminum support treated in this way, imagewise exposed, developed and plate-made, and then set in a printing machine to start printing.

〔Effect of the invention〕

When using the lithographic printing plate support obtained according to the present invention,
It is possible to create a lithographic printing plate that is free from printing stains and has excellent rigidity resistance and water retention.

The present invention will be specifically described below based on examples.

[Example 1] (1) A nylon brush with a thickness of 0.48 mm and a height of 46 mm was attached to a metal roll with a diameter of 340 mm and a width of 400 mm.
Using a brush roll with uniformly flocked hair, JI
A 300 mm wide Al web of S1050 was roughened during continuous operation.

This brush roll is driven by a motor so that it can be rotated and also raised and lowered.

Three brush rolls are used, and the two front and rear brush rolls rotate in the same direction as the aluminum web traveling direction, and the middle brush rotates in the opposite direction.

The aluminum plate was roughened by applying pressure to the aluminum plate using a lifting device so that the rotation speed was 300 rpm and the motor load was 2 kIIl. Note that alumina powder #360 was used as the abrasive material.

The resulting substrate had a centerline average roughness of 0.55μ.

Next, this substrate was heated with No. 3 sodium silicate aqueous solution 2.5% at 70°C.
The resulting substrate was immersed in something warmed for 20 seconds.
■] (Comparative example (1)).

(2) Fix the nozzles in a row at 35mm intervals, and
A 300 mm wide Al web of S1050 was roughened during continuous operation.

As the slurry, 30 kg of alumina and water slurry 'J- (40 volume drops) containing #180 alumina abrasive was used.
It was made to join the water stream discharged from the nozzle at a pressure of /cI11, and the above-mentioned joined water was made to collide with the surface of the aluminum from an angle direction of 45° to roughen the surface.

Next, the combined water of the above slurry and 30 μkg/ClTl pressure water was made to collide against the aluminum surface at an angle of 135° to roughen the aluminum surface again.

The center line average roughness of the obtained substrate was 0.5μ.

Next, this substrate was treated with No. 3 sodium silicate in the same manner as substrate CI,], and the obtained substrate was designated as substrate [II] (Comparative Example (
2)).

(3) An Al web roughened under the conditions of Comparative Example (1) is wound up, and then the grain is modified by a liquid honing method. This liquid honing method uses an alumina/water slurry (40% by volume) containing #360 alumina abrasive.
was used to join the water stream being discharged from the nozzle at a pressure of 20 kg/ClTi, and 60 kg/ClTi was applied to the aluminum surface.
The surface of the obtained substrate was roughened by colliding with the substrate at an angle of 0.60μ.

Next, this substrate was treated with No. 3 sodium silicate in the same manner as the substrate [■], and the obtained substrate was used as the substrate [■] (Example (1)
).

A photosensitive layer was provided on the thus prepared substrates [I] to [■] by coating the following composition so that the coating weight after drying was 2.5 g/rrX.

/' \ As described in Example 1) The photosensitive lithographic printing plate thus prepared was exposed to light for 50 seconds using a 31W metal halide lamp through a transparent positive film in a vacuum printing frame from a distance of 1 m. Once done, a 5.26% aqueous solution of sodium silicate (pH
= 12.7).

After developing in this manner, the film was thoroughly washed with water and gummed, and then printed using a conventional procedure.

The printing machine used was Sprint 25 (manufactured by Kodot Printing Co., Ltd.).

The printing results are shown in Table 1.

[Example 2] Mechanical surface roughening was performed according to the operations (1), (2), and (3) of Example 1 above. After finishing roughening, wash with water, 1
The amount of dissolved aluminum was 6 g/m' (substrate
■]) or 2.5 g/m' (substrate CVI, [
■〕). After washing with water, it was immersed in a 30% nitric acid aqueous solution for 1 minute to neutralize it, and then thoroughly washed with water.

Further, the weight of the anodized film in 20% sulfuric acid aqueous solution was 1.5
After anodizing using a direct current so that the ratio of
It was soaked for 1 minute at 0°C and washed with water.

The boards [■], [■] and [VI
], a photosensitive layer having the following composition was applied, and the coating weight after drying was 2.0.
g/m' to form a photosensitive layer.

Photosensitive liquid + ""'N -(4-hydroxyphenyl)methacrylamide/2-hydroxyethylmethac□ IJ l/
-) /acrylic nitrile/methylmethacrylic acid (=15:□ 10
:30:38 near molar ratio) copolymer 1 ('P'' average molecular weight 60,000) 1 5,0
g'1 Hexafluorophosphate, a condensate of 14-diazodiphenylamine and formaldehyde 0.5g Phosphorous acid 0.05g Victoria Pure Blue BOH (manufactured by Odugaya Chemical Co., Ltd.)
・---0,1g 2-methoxyethanol
A 100 g photosensitive lithographic printing plate thus prepared was exposed to light for 5.0 seconds from a distance of 1 m using a 3 kW metal halide lamp through a transparent negative film in a vacuum printing frame, and then developed with a developer having the following composition. The mixture was gummed with an aqueous gum arabic solution to prepare a lithographic printing plate.

Developer solution l' Sodium sulfite 5g1
Sl/lium carbonate 5g water
Using the 1000 g printing plate thus prepared, printing was carried out in the usual manner.

Table 2 [Example 3] After washing the excellent substrates [I] to [■] in Example with water, the etching amount of the aluminum surface was 2.5 g/m' or 6 at a temperature of 60°C in a 30% caustic soda aqueous solution. g/
The film was etched so as to have an angle of m', washed with water, and then immersed in a 20% nitric acid aqueous solution to remove insoluble residues (smut) on the surface. After washing with water, in a 0.7% nitric acid aqueous solution,
The surface was electrochemically roughened using an alternating current waveform as described in Japanese Patent No. 19191. The electrolytic conditions were Va = 12.7 volts, Vc = 9.1 volts, and the anode specific electricity amount was 160 chrome/dm''. After removing the smut on the surface, the anode was heated in 20% sulfuric acid. An oxide film of 2 g/m" was provided.

On the substrate obtained in this way, [■] ~ CIX']
The same photosensitive layer as in Example 1 was coated with a coating weight of 2.5 after drying.
g/m", and after exposure and development, printing was carried out by ordinary means. The results are shown in Table 3.

From the results shown in the table above, it can be seen that a substrate with excellent stain resistance and good rigidity resistance can be obtained under conditions where the amount of etching is small.

[Example 4] Substrates [■] to [IX] prepared in the same manner as in Example 3 were washed with water, immersed in a 2% sodium silicate aqueous solution at 70°C for 1 minute, washed with water and dried to form supports [X], [ xI] and [X■]
It was created. A photosensitive solution having the same composition as that used in Example 2 was applied to the surface of this substrate so that the dry weight was 2.0 g/m', dried at 80°C for 30 seconds, exposed and developed. A lithographic printing plate was created. When printing was carried out using this lithographic printing plate in a conventional manner, as in the case of the positive photosensitive liquid of Example 1, clear printed matter was obtained, and the non-image areas were also resistant to staining.

Claims (1)

[Claims] 1. A method characterized by forming primary grains on at least one side of an aluminum plate by a brush grain method, and then modifying the shape of the primary grains by a liquid honing method. A method for producing a support for a lithographic printing plate. 2. A patent characterized in that the liquid honing method is a method in which high-pressure liquid is jetted out from a nozzle at high speed, a slurry containing fine abrasive powder is combined with the jetted flow, and the combined flow is caused to collide with the surface of an aluminum plate. A method for producing a lithographic printing plate support according to claim 1. 3. Using the brush grain method on the surface of the aluminum plate,
After forming the primary grains, the shape of the primary grains is modified by a liquid honing method, and then the grains are electrochemically superimposed in an electrolytic solution consisting of hydrochloric acid, nitric acid, or a combination thereof. A method for producing a support for a lithographic printing plate, characterized by: 4. A patent characterized in that the liquid honing method is a method in which high-pressure liquid is jetted out from a nozzle at high speed, a slurry containing fine powder of abrasive material is merged with the jetted flow, and the merged jet is caused to collide with the surface of an aluminum plate. A method for producing a lithographic printing plate support according to claim 3. 5. The method for producing a support for a lithographic printing plate according to claim 4, wherein chemical etching is performed between the mechanical grain and the electrochemical grain.