JPS62231261A - Method and apparatus for exposing of photosensitive lithographic printing plate - Google Patents

Abstract

PURPOSE:To decrease blurring and spoilage by exposing the titled plate by such exposing rays in which the greater part have within 10 deg. angle with the optical axis of the main exposing rays. CONSTITUTION:A light source contg. >=35% 375-425nm rays with respect to the emitted rays in a 300-700nm range is used and the plate is exposed by the exposing rays in which the greater part are within 10 deg. angle with the optical axis of the main exposing rays. The PS plate is provided with a photosensitive layer on a base having a hydrophilic surface and is preferably formed by providing the photosensitive layer on the base which is formed by anodizing an aluminum sheet and is subjected to a hydrophiling treatment at need. The optical axis of the main exposing rays refers usually to the axis connecting an optional point on the PS plate and the center of the light source lamp in the direction where the light intensity is highest at the optional point on the PS plate. The method for obtaining the rays includes a method for utilizing the parallel rays of the sunlight, method for increasing the distance between the light source lamp and the PS plate and a method for providing a cylinder to the conventional exposing device. The blurring and spoilage of the PS plate are thereby decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for exposing a photosensitive lithographic printing plate 111, and more specifically to a method and apparatus for exposing a photosensitive lithographic printing plate 111, and more specifically,
A light source is used that contains a light beam of 375 to 4A cojnm for the emission beam in the range of This is a book about a method and an exposure apparatus for exposing a photosensitive lithographic printing plate using light rays. In order to form a perfectly exposed image, the 28th plate and the original picture overlaid on it must be in perfect contact with each other, but for this purpose, the 28th plate and the original picture are placed between a rubber sheet and a pressure bonding glass, and a vacuum is created between them. The so-called vacuum contact exposure method is used, in which the film is brought into close contact with the film.

However, in the case of an original image made of several sheets of film, the film is pasted onto a transparent base with tape as a so-called pasting film, but due to the pasting tape and dust that got between the 28 plate and the original film, the film sticks tightly. There is a problem in that defects occur and so-called burnt blur occurs around the tape or dust.

In fact, blurring is the biggest cause of the defective rate of 28 plates at the printing site, the so-called sharpness rate.

Furthermore, when printing with 28 plates, the area of halftone dots from the plate to the printed matter increases, and the dot gain of the dots increases. For this reason, positive-tone PS plates make full use of the thinning caused by exposure to reduce the halftone dot area on the plate, but in the case of negative-tone 28 plates, due to its characteristics, printing thickening inevitably occurs, so the plate The area of halftone dots on the top increases. Therefore, when printing with a negative 28 plate, it is desirable to minimize dot thickening by low exposure, but conversely, low exposure can result in problems such as a decrease in rigidity and film strength. It had become.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a 28-plate exposure method and exposure value +1 that reduce printing blur and have a low sharpness rate.

Another object of the present invention is to provide an exposure method and an exposure apparatus for obtaining a negative type 28 plate with little dot thickening and good printing durability and film strength.

[Structure of the invention]

The present inventors have made various studies in order to achieve all of the above objects, and as a result, have accomplished the present invention.

The present invention provides 375-412! for emission light in the range of 300-700 nm. The present invention is an exposure method and an exposure apparatus that use a light source that includes a light beam of 314 nm or more, and that uses a light beam in which most of the exposure light beam is at an angle of 10 degrees or less with respect to the main exposure beam axis.

The plate making method according to the present invention will be explained in detail below.

The 28th plate used in the present invention is formed by providing a photosensitive layer on a support having a hydrophilic surface, preferably a support which has been anodized with aluminum I&I and then treated to make it hydrophilic if necessary. The aluminum plates used include pure aluminum and aluminum alloy plates, on which the photosensitive layer is provided. Various aluminum alloys can be used, such as silicon, copper, manganese,
An alloy of aluminum and metals such as magnesium, chromium, zinc, lead, bismuth, and nickel is used. These compositions.

In addition to some iron and titanium, it also contains one other negligible impurity.

The aluminum plate is preferably grained, but before that, if necessary, the surface is pretreated to remove rolling oil from the surface and expose a clean aluminum surface.

For the former, solvents such as Trifury, surfactants, etc. are used. and for the latter, sodium hydroxide,
Methods using alkaline etching agents such as potassium hydroxide are widely used. As the graining method, a mechanical graining method, a chemical graining method, an electrochemical graining method (so-called electrolytic etching method), etc. are used.

The grained aluminum plate is washed with water if necessary, and then chemically etched if necessary.

The etching solution used is usually selected from aqueous base or acid solutions that dissolve aluminum. in this case,
The etched surface must be free of aluminum or a coating different from aluminum derived from the etching solution components. Examples of preferred etching agents include hydroxylated basic substances.
Jum, potassium hydroxide, trisodium phosphate, disodium phosphate, tripotassium phosphate, dipotassium phosphate, etc.; examples of acidic substances include sulfuric acid, persulfuric acid, phosphoric acid, hydrochloric acid, and salts thereof.

Etching is performed by immersing the aluminum plate in the above etching solution or applying the etching solution to the aluminum plate, and the etching amount is 0.7 to 1097 m.
It is preferable that the processing be performed so that the range of 0.2 is achieved.

For the above-mentioned etching, it is desirable to use an aqueous base solution because of its high etching speed. In this case, since smut is generated, desmut processing is usually performed. The acids used in the desmutting treatment include nitric acid, sulfuric acid, phosphoric acid, chromic acid, butic acid, and hydrofluoric acid.

The etched aluminum plate is washed with water if necessary, and then anodized. Anodic oxidation can be carried out by a method conventionally used in the field of wood.

Specifically, sulfuric acid and phosphoric acid.

When a direct or alternating current is passed through aluminum in an aqueous or non-aqueous solution containing chromic acid, g-acid, sulfamino acid, benzenesulfonic acid, etc. or a combination of two or more of these, an anodic oxide film is completely formed on the surface of the aluminum support. be able to.

The processing conditions for anodic oxidation vary depending on the electrolyte used, so they cannot be determined unconditionally, but in general, the concentration of the electrolyte is /-10% by weight, the solution temperature is 70C, the current density is 0 .1~to ampere/dm2.'f1!pressure/-10
OV, Electron M13) 13) il J O A range of seconds to 10 minutes is appropriate.Among these anodizing treatments, British Patent No. 1.
The method of anodizing at high current density in sulfuric acid used in the invention described in No. 74r and described in U.S. Pat. No. 5,31/, t6/ A method of anodic oxidation using phosphoric acid as an electrolytic bath is preferred.

The aluminum support that has been subjected to such treatment is then subjected to a hydrophilic treatment as necessary. Seven preferred hydrophilic treatments include treatment with an aqueous solution containing at least seven groups of carboxylic acid, sulfonic acid, phosphonic acid and/or salts thereof. Specific compounds include gum arabic,
Carboxymethyl cellulose, carboxyethyl cellulose, carboxydimethyl hydroxyethyl cellulose,
alginic acid, polyacrylic acid and acrylic acid derivatives,
copolymer of vinyl methyl ether and maleic anhydride,
These are a copolymer of vinyl acetate and maleic anhydride, polyvinyl sulfonic acid, and salts thereof. These compounds may be used in combination of two or more, and if necessary, other compounds such as water-soluble metal salts (e.g. zinc acetate) as described in U.S. Patent No. J, 140.4c26, or It may contain fine particles such as silica and titanium dioxide, or dyes for the purpose of preventing halation.

After these compounds are dissolved in water, an organic solvent is added as necessary, and this is applied onto the anodic oxide film of an aluminum plate by a known method such as dip method, S roll coating method, bar code method, etc., and after drying, it is further coated. If necessary, the excess amount is removed by washing with water, or by immersion in a heated aqueous solution followed by washing and drying, a sheet 1- composed of the above-mentioned compound is formed.

The concentration of the coating liquid is preferably about 0.00 to 1% by weight, and the coating weight after drying is preferably about 1 to 100%/rnz.

Yet another preferred hydrophilic treatment is treatment with an aqueous solution of an inorganic salt. As non-keyaki salt, U.S. Patent No. 7/μ, 066 and U.S. Patent No. 3. /13)
, 4 & 47, there are alkali metal silicates, such as sodium silicate, fluorinated zirconate, etc., and the weight after treatment is about 7 to 1.
00kfl/fn2 is preferred.

A photosensitive layer is provided on the lithographic printing plate support treated in this way. Some of the typical ones are explained below.

■ Composition made of diazo resin The diazo resin represented by the condensate of p-diazodiphenylamine and paraformaldehyde may be either water-soluble or water-insoluble, but is preferably a water-insoluble and ordinary organic solvent. soluble ones are used. Particularly preferred diazo compounds include compounds having two or more diazo groups in one molecule, such as salts with phenol, salts with sulfonic acids, etc. of condensates with p-diazodiphenylamine formaldehyde or acetaldehyde. be. Although the diazo resin may be used alone, it is preferable to use it together with a binder. Since various polymer compounds are known as binders, they can also be used for the present invention. Is the binder content in the photosensitive layer approximately ? If the amount of binder is increased (that is, the amount of diazo resin is decreased), the photosensitivity will naturally decrease, but the stability over time will decrease. The optimum amount of binder is about 70-90% by weight.

(2) Composition comprising an 0-quinonediazide compound A particularly preferred 0-quinonediazide compound is. - Naphthoquinone diazide compounds, many types of which are known,
All of them can be used. These 0-quinonediazide compounds.

Although it can be used alone, it is better to use an alkali-soluble resin together as a binder. Examples of the alkali-soluble resin include novolak type phenol resin and t-butylphenol formaldehyde resin, and the content of the binder in the photosensitive layer is about to-iro weight.

■ Compositions consisting of photosensitive azide compounds Suitable photosensitive azide compounds include aromatic azide compounds in which the azide group is bonded directly or via a carbonyl group or a sulfonyl group to an aromatic ring. is decomposed to produce nitrene, which undergoes various reactions and becomes insolubilized. Many photosensitive azide compounds are known and can be used for the present invention, but a binder is usually used in the composition as in the case of other photosensitive resins.

In addition, the photosensitive composition may contain -CH in the main chain or side chain.
A composition consisting of a polymer compound containing =CH-C0- group, a photopolymer composition consisting of an addition polymerizable unsaturated compound, (a
) Compounds that completely form strong #R upon combustibility; (b) Compounds that can be cleaved by acids (e.g., polymer compounds with orthocarboxylic acid ester groups: JP-A-Sho J-6-/73)
There are highly sensitive positive-working compositions made of silyl ether polymer compounds described in Japanese Patent Application No. 44, silyl ether polymer compounds, etc., which can be used for the present invention. Those photosensitive compositions are
A large number of specific techniques have been introduced in detail in literature, and these techniques can be used or applied. Among these, those using negative and positive type diazo resins (1) and (2) are particularly preferred.The composition of the present invention is dissolved in a solvent that dissolves each of the above components, coated on a support, dried, and made into a PS. You can get the version.

Using the PSH thus prepared, the photosensitive layer of the PS plate and the original film are brought into close contact with each other in a vacuum, and then exposed to an ultraviolet light source.

Most of the light beams used for exposure are such that the angle is within 70 degrees with respect to the main exposure beam axis, and preferably 20 or more of the light beams are at angles within 70 degrees, preferably #F. A ray whose angle is within r degrees.

The main exposure beam axis is the direction of the strongest light intensity at any point on the 28 plate, and is usually the axis connecting any point on the PS plate and the center of the light source lamp.

To perform optical tt measurements within an angle of 70 degrees, a cylinder with a maximum angle of 70 degrees (for example, diameter !α, high - g21.3
The inside of a 6 cm cylinder (the maximum io degree of light can be incident on the side wall) is blackened, and the light tt measurement of a circular shape with a diameter jcrn with and without the cylinder is calculated from the scene ratio. , Here, for ease of measurement, it is defined as the measured value at the point where the perpendicular line from the center of the lamp to the 28th plate intersects on the 28th plate.

Conventionally, fluorescent lamps, carbon arc lamps, mercury lamps, metal halides, etc. have been used as exposure light sources for PS plates, but since these are rod-shaped, they are not only exposed to light rays from various directions. In order to increase exposure sensitivity, scattering plates were placed on the back and sides of the lamp, resulting in exposure to scattered light.

The methods of obtaining the light beam t- as in the present invention include (1) the use of parallel rays of sunlight, (2) the method of increasing the total distance between the light source lamp and the 28 plate, and (3) the method of using the conventional exposure system as described above. Method of providing a cylinder (4) A method of providing continuous photons arranged in a nest-like manner between the light source and the 28th plate.
, F, PRINTERT printer) series" can be raised, and the angle 4.
By using the honeycomb board B, it is possible to obtain a ray with an angle i within 5' degrees. The bright room printer (rF, F, PRINTERC printer) series" is a point light source type bright room printer whose purpose is to obtain a "high illuminance distribution over the entire area" by running a lamp house, and to improve reversal accuracy by using "parallel rays." There is a difference in the amount of light between the center and the periphery, and the rays are perpendicular to the film in the center, but diagonal in the periphery. Poor accuracy in enlarging, alignment of female and male versions of envelope letters, uneven line width in thickening and thinning, etc.)
tl-This is the best improved bright room printer.

(5) A method of creating an ideal light source by making the entire light source body small spherical and completely preventing scattered light from the back side and measurement. (6) Uniform illuminance by installing a condenser lens between the light source and the 28 plate. For example, the method has been improved so that ) can destroy the whole country. Condenser lenses are used to improve the difference in light intensity between the center and periphery (1) as shown above.

(In 71+61, the light source is a small sphere.
series" (diameter J (combination of 71m spherical electrodeless lamp [Magnelux MD series] and condenser lens)
Hiromu (Vot, i! Near 1J, P//~P/J', Microwave discharge light source device) is described in detail in ``Microwave discharge light source device''. Electrodeless lamps have electrodes that cause the lamp to fail due to a decrease in light output. Since the lamp has been removed and the blinking life has been more than doubled, and since the lamp is a small sphere, it is an ideal point light source with improved light distribution accuracy and easy light distribution control.

Furthermore, by providing a light reflecting surface, such as a paraboloid, on the back of the light source like the Magnelux MD series, it is possible to expose the light through a condenser lens after the light is totally reflected on the back and side surfaces, making effective use of all the light. be able to.

In these methods, (1) is difficult to work with and it is difficult to control the exposure amount, and in (2), ha
In addition, the light intensity decreases significantly (in 31, the exposed area decreases extremely and only a part of the light beam is used, so the light intensity decreases significantly; (4)
There is no problem with the exposed area, but as in (3),
The amount of light decreases significantly, and (5) has drawbacks in the method of preventing scattered light (for example, in the case of absorption by a black body, a problem of heat generation occurs) and in uneven illuminance. On the other hand, methods (6) and (7) are the 4th best method because it is possible to design the condenser lens so that the decrease in sensitivity is the least and the illuminance is uniform.

Conventionally, condenser lenses have been used in bright room printers just to make the illuminance uniform, but surprisingly, when used for 28 plates, they have been shown to reduce blurring and reduce negative tone PS.
In [, we found an effect that completely prevents dot thickening and provides sufficient printing durability.

Moreover, in the case of the 28-version film, unlike the reversal film, it does not have to be reversed many times, and the accuracy of the attachment of the contact portion is not as strict as that of the reversal film, so it is sufficiently useful for the 28-version film.

However, when a conventionally used bright room printer with a condenser lens was used, the sensitivity was lower than that of a conventionally used printer for PS plates. This is because the bright room film has the long wavelength side cut off with a filter to enable work in the bright room, and the wavelength range of 300 to +00 nm (
Because it is a silver halide photosensitive material that has a main photosensitive range at
This is because even if a part of the light beam is used because it is higher than the plate, there are many extra wavelength light beams in order to obtain sufficient exposure sensitivity.

In order to obtain sufficient exposure sensitivity as a diazo type 28 plate, the light source used in the present invention has a light beam of 317 to Hiroko jnm of 314 nm to an emitted light of JOO to 7 oonm.
Use a light source that includes the above. Especially 375~φJ
A light source with a peak is preferable for emitting light.Hiroshi!
It is more preferable that at least 100% of the carbon dioxide is contained. Such light #i
In order to obtain L, metal halide lamps and electrodeless lamps filled with materials used in metal halide lamps can be used, and in particular, a condenser lens is placed between the light source in the form of a small sphere and the 28 plate. It is preferable that the light source is a book, and furthermore, a parabolic reflector, for example, is arranged on the back and side of the light source.

Electrodeless lamps do not have electrodes inside the lamp, so there are no problems such as reactions between the enclosed metal and the electrodes, so there are fewer restrictions on the enclosed substance, and the choice can be made relatively freely. It's easy to get caught.

Such an exposure device is not a device like a brightroom printer, in which the original film and then the printing film are layered on glass, then sealed with a rubber sheet, and then exposed from below, but a device that suits the usage characteristics of the 28 plate. That is, a method in which the original film is placed on top of the 28th plate, adhered to it with a glass frame, and then exposed from above the device.

In the same way, after attaching a glass frame, the glass frame is reversed and exposed from below inside the device, and the same original image 't one 28
It is possible to use a plate printing machine that exposes a large number of plates by setting 28 plates vertically or downwardly.

The 28th plate exposed with K in this manner is developed with a developer and becomes a lithographic printing plate.

[Effects of the present invention]

According to the present invention, the printing blur of the 28th plate can be reduced, and the sharpness rate can be lowered.

Further, according to the present invention, a lithographic printing plate with little dot thickening and good printing durability and film strength can be obtained from a negative type 28 plate. Explain. However, the present invention is not limited to these Examples. Incidentally, in the examples, the word "grim" means "heavy".

Examples 1 to 7 and Comparative Examples a to d 0.3 mm thick aluminum plate (material/(7J-(7
1'i) After cleaning and degreasing, the surface was grained using a nylon brush and a pumice-water suspension of 30 mesh, and thoroughly washed with water. This board is ≠50C1
7') After etching by immersing the film in an aqueous sodium hydroxide solution for 7 seconds and washing with water.

Furthermore, it was immersed in 204R nitric acid for 20 seconds and washed with water. The amount of etching on the grained surface at this time was approximately jf/m2. Next, this plate was heated using 7-width sulfuric acid as an electrolyte, and the light density/
After providing a DC anodic oxide film of JS'/FF12 at jA/dm2, it was washed with water and dried.

The following photosensitive solution was applied to the aluminum plate subjected to such treatment and dried for too many minutes to obtain a positive type PSIa. The amount of application after drying is! It was 27m2.

Photosensitive liquid injection■ Notes described in Examples/in the specification of US Patent No. 5, No. 31,702 ■ US Patent No.
What is described: After exposing this positive PS plate in close contact with the original film using all exposure equipment, use Fuji Photo Film ■'s automatic developing machine R00E and using the same company's positive developer. DP
-4 was diluted with water in a ratio of 1 to 1, and developed at 0 to 10 seconds. The results are shown in Table 2. In the table, the exposure time is such that a thin line of
The effective sensitivity on the plate was adjusted so that fine lines of /jm could be reproduced. In addition, the grayscale on the plate (
Density difference o, /r: (manufactured by Fuji Goshin Film ■) sensitivity.

The blur width is based on 10θμ, assuming adhesive tape, etc. Inserted between the Q-related plain screen and the 28th edition, the area where the halftone dots are blurred (the area where the halftone dot area is smaller than the normal area) is -
Expressed as distance from sedge. In addition, the film was placed between a small dust T-PS plate and the original film, and the degree of blur was evaluated on a 6-rank scale from average (good) to F (bad). Normally, the usable level is C rank or higher. From the table, the light beams of Examples 1 to 7 according to the present invention are used, and the light beams of Comparative Examples a and d conventionally used in the 28th edition are used. It can be seen that the blur width is narrower and the printing blur is reduced compared to the light rays of similar bright room film printer comparison examples I and C.

However, in Examples 1 to 3, the exposure sensitivity was extremely reduced.

Furthermore, the exposure time of the bright room bright printer Example ≠ and B with a condenser lens is relatively short compared to Examples 7 to 3, but longer than the PS plate printer comparative examples a and d. On the other hand, in Examples j and 7, which used a light source that contained 375 N hiroko, tnm light at 35 degrees or more and had an emission spectrum peak within this range, the exposure time was longer than that of a conventional PS plate printer. This is the best method that can reduce the blurring at the same level.

Note that in Comparative Examples a to d, printing blur could be reduced by reducing the exposure amount, but the grayscale sensitivity and effective sensitivity were low, and the halftone dots were not thin enough, so the mid to shadow halftone dots Only printed matter with poor fc tone reproducibility was obtained.

Example, r-/≠ and Comparative Example e -h An aluminum plate surface-treated in the same manner as Example/ was immersed in No. KJ silicate sodaco, j4 solution at 700C for 30 seconds, washed with water, dried, and coated with the following coating solution. was coated and dried to obtain a negative PS plate. The coating amount after drying was 2.097 m2.

Note ■ As described in Example 1 in the specification of US Pat. No. 3.27.

This negative PS plate was used as Example/-1 and Comparative Example a%
After exposing the film in close contact with the original film using the exposure device used in step d, use the company's negative developer D N-J C with water/pair with the Fuji Photo Film @ model automatic processor ZOOV. The film was diluted to 100 ml and developed at 100 ml. The results are shown in Table λ.

In the table, the exposure time is the time at which the halftone dots of to% of the original film can be reproduced with a wide width on the printing plate. , and also showed grayscale solid sensitivity.

For blurring, a small piece of dust was placed between the 28th plate and the original film J04 plain screen, and the blur around the dust (thickness of the halftone dots around the dust) was visually judged.

In addition, the image area strength is DN-JC (/:
/l by hand and rubbing with a nylon brush. The printing durability was examined using KOR (manufactured by Idelberg).

From Table 2, those using the light beam of Example r-/≠ according to the present invention are Comparative Examples e and h conventionally used for PS plates and Comparative Example f1g of a bright room film printer similar thereto.
It can be seen that the film strength and printing durability are good because the printing blur is reduced and the gray scale solid sensitivity is increased compared to the light beam.

Furthermore, among Examples r-/μ, Examples t to IO have extremely long exposure times, whereas the actual exposure times were longer in Examples 1/ and /J, which used conventional bright room printers. On the other hand, Examples 1 and 1 using the light source according to the present invention had a lightless time comparable to that of the conventional PS plate printer comparative examples e and h.

In Comparative Examples 0 to h, it was possible to improve the film strength and printing durability by increasing the exposure amount and increasing the solid sensitivity, but only prints with large halftone dots and poor tone reproducibility were obtained. There wasn't.

Claims (13)

[Claims] (1) A method for exposing a photosensitive lithographic printing plate, characterized in that most of the exposure light beams are exposed at an angle of 10 degrees or less with respect to the main exposure light beam axis. (2) The exposure method according to claim 1, wherein the light beam is obtained from a light source in which 375 to 425 nm of light rays are included in 35% or more of the emission light of 300 to 700 nm. (3) The exposure method according to claim 2, wherein 90% or more of the light rays are contained within the range within an angle of 10 degrees. (4) The exposure method according to claim 2, wherein the light beam passes through a condenser lens placed between the light source and the photosensitive planographic printing plate. (5) The exposure method according to claim 4, wherein the light source is a small spherical light source. (6) The exposure method according to claim 5, characterized in that a reflective surface is disposed on the back surface of the light source. (7) The exposure method according to claim 5, wherein the light source is a metal halide lamp or an electrodeless lamp. (8) 3 for emission light in the range of 300-700 nm
An exposure apparatus for a photosensitive lithographic printing plate, wherein most of the light beams obtained from a light source containing 35% or more of light beams of 75 to 425 nm are at an angle of 10 degrees or less with respect to the main exposure beam axis. (9) The exposure apparatus according to claim 8, wherein 90% or more of the light rays are contained within an angle of 10 degrees or less. (10) An exposure apparatus according to claim 8, characterized in that a condenser lens is disposed between the light source and the photosensitive planographic printing plate, and the light beam passes through this lens. (11) The exposure apparatus according to claim 10, wherein the light source is a small spherical light source. (12) The exposure apparatus according to claim 11, characterized in that a reflective surface is disposed on the back surface of the light source. (13) A device in which the device exposes the original film to light from above the device after the original film is brought into close contact with the photosensitive lithographic printing plate;
A device that exposes from below inside the device by inverting the contact frame, or
11. The exposure apparatus according to claim 10, which is a printing press that exposes a large number of original films by setting a photosensitive lithographic printing plate vertically or downwardly.