JPH01210343A - Lithography and lithographic plate - Google Patents

Abstract

PURPOSE:To make possible lithography which does not cause a positional shift or a plate cut and is especially suited to light printing by printing with a lithographic plate fixed to the surface of a transparent plate cylinder using a photopeel-type adhesive. CONSTITUTION:Printing is performed by fixing a lithographic plate to a transparent plate cylinder using a photopeel-type adhesive. After printing, light is projected to the rear surface of the lithographic plate through the surface of the transparent plate cylinder, and the lithographic plate is removed from the plate cylinder by decreasing the adhesion of the photopeel-type adhesive. The photopeel-type adhesive is for instance, cured through polymerization by light projection, resulting in the decrease of adhesion. At the same time, a tension concentrates in the surface between the plate cylinder and a cured adhesive layer and the adhesive layer is easily peeled off the surface of the plate cylinder. The adhesive of the above nature is of the solvent-type and is roughly classified as the rubber-based one and the acryl-based one. The acryl-based adhesive is superior to the rubber-based adhesive in terms of oil-proofness and in addition, allows molecular designing which gives a variety of adhesive properties. For these reasons, it is advantageous to use the acryl-based adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to printing automation in the field of light printing, and particularly to a lithographic printing method and a lithographic printing plate used therein.

[Conventional technology]

In planographic printing, when attaching a plate to the plate cylinder of a printing press, a method has conventionally been adopted in which the edges of the plate are fixed using so-called grippers. This method is desirable in heavy printing using a metal plate support such as aluminum, and can sufficiently prevent the plate from shifting during printing.

However, when a thin plate material is used in light printing, such as a plate using a support made of paper, polymer sheet, aluminum foil, or a composite material made of aluminum foil and other materials, the plate fixing method using the gripping method described above is used. is not necessarily a desirable method. In particular, it is known that when the support is extremely thin, problems such as plate breakage at the gripping portion and misalignment of the plate during printing occur.

However, there is a strong need for fully automated printing in the field of light printing technology, including automatic plate making technology and technology for continuously supplying plates from the plate making department to the printing machine.

is desired. In this case, the plate material must be flexible and as thin as possible so that it can be supplied in a roll and is easy to handle.

However, when trying to attach such materials to a printing machine with a conventional gripping mechanism, they tend to wrinkle during handling.
Misalignment often occurs during printing, making it impossible to print in multiple colors, or causing various problems, such as printing plates running out.

For these reasons, the thickness of the photosensitive layer should originally be about 1 μm, and the thickness of the support should be 50 μm, considering the roughness required for the support. In printing plates, in order to provide strength to the plate material, it has been necessary to increase the thickness of the support or to use a composite support with excellent strength.

On the other hand, if it becomes possible to print using a thin plate material with a thickness of, for example, about 50 μm, the photosensitive layer can be formed by vapor deposition, CVD, or photo-CVD.

It becomes possible to perform the process by winding in a vacuum device using a dry process such as sputtering. In other words, photosensitive thin films can be manufactured using a dry process, and printing plates can be developed based on new principles. From this point of view as well, there is a need for a printing system that can print thin-layer printing plates.

Continuous processing of film bodies of about 15 μm, such as films with functional thin films or aluminum foils, is now easily carried out, so there are almost no problems when producing plate materials. What is needed is how to print using such plate materials.

Several methods have been proposed for printing using thin plate materials. An example of this is to make a frame that fits precisely onto the printing press cylinder, and then to place the thin plate material into the frame and then to attach it to the cylinder. However, this method is not suitable for automatic feeding. On the other hand, there has been an attempt to coat the back of the plate with a magnetic material and attach it to the iron plate cylinder using magnetic force, but in order to provide a strong magnetic force, the layer of magnetic material coated on the back of the support must be made thicker. This makes it unsuitable for thin printing plates. On the other hand, a method has also been proposed in which a strong magnet is installed on the plate cylinder in order to form a strong magnetic field in the plate cylinder. In this case, if iron foil is used as the plate material, it is possible to achieve the purpose of mounting the plate. However, the presence of such magnetic fields is undesirable when computer-controlled printing presses are used.

[Problem to be solved by the invention]

Accordingly, an object of the present invention is to provide a lithographic printing method that is particularly suitable for light printing and that does not cause positional deviation or plate breakage during printing.

Another object of the present invention is to provide a lithographic printing plate used in the above method, as well as a method for easily removing the plate from the plate cylinder after printing is completed.

[Means to solve the problem]

The present invention provides a lithographic printing method characterized in that printing is performed by fixing a lithographic printing plate to the surface of a transparent plate cylinder using a light-peelable adhesive.

The present invention also provides a lithographic printing plate provided with a light-peelable adhesive layer on the back surface for carrying out the above method.

The present invention is further characterized in that after printing is completed, light is irradiated onto the back side of the lithographic printing plate through the transparent plate cylinder surface to reduce the adhesiveness of the light-peelable adhesive and the lithographic printing plate is detached from the plate cylinder. The present invention provides a lithographic printing method.

The photo-peelable adhesive used in the present invention is polymerized and cured by light irradiation, reducing its adhesive strength and causing stress concentration at the interface between the plate cylinder surface and the hardened adhesive layer during peeling. , the adhesive layer has a property of being easily peeled off from the surface of the plate cylinder.

The light-peelable adhesive suitable for the purpose of the present invention is a solvent-based adhesive, which can be broadly classified into rubber-based and acrylic-based adhesives. Among the two, it is advantageous to use acrylic adhesives because acrylic adhesives have better oil resistance than rubber-based adhesives and also allow for molecular design to provide various adhesive properties. Various compositions of acrylic adhesives are described in, for example, Encyclopedia of Adhesion and Adhesion, edited by Akira Yamaro, Sanbu, Asakura Shoten, (1988).

A preferable example of the adhesive used in the present invention is an acrylic adhesive described in PCTWO8110O309, which is given a tackiness reducing function by utilizing curing by ultraviolet exposure.

Preferred adhesives used in the present invention include 10 to 25 parts by weight of glycidyl methacrylate and isooctyl acrylate.
) 90 to 75 parts by weight of the copolymer. Such an adhesive can be obtained by copolymerizing each monomer in a solvent such as a mixed solvent of ethyl acetate and isopropyl alcohol.

The adhesive used in the present invention is a so-called pressure-sensitive adhesive, and its required property is that when a certain force is applied, the adhesive molecules flow in the direction of that force, creating adhesive force with the adhered object. . However, when a force is applied next, the adhesive must not peel or flow due to its own viscoelasticity.

In fact, as stated in the above patent, by changing the copolymerization ratio of glycidyl nucleate/isooctyl acrylate from 5/95 to 35/65, the adhesive strength of the adhesive on glass, for example, can be improved by changing the adhesive strength of the adhesive on glass ( 33g of adhesive on a biaxially stretched PET film with a thickness of 38μm
/m' is painted) and evaluated: 1120
g/cm to 88 g/cm. Therefore, by optimizing the polymerization ratio and blending other polymers, a pressure-sensitive adhesive with the most desirable adhesive strength can be designed.

Now, when adhesive force is obtained by the adhesive in this way, the following two methods can be considered to reduce the adhesive force and easily peel off the adhesive from the adhered object.

(1) A method in which adhesive molecules are cut and disintegrated using photochemical reactions, causing the adhesive to lose its adhesive properties due to a decrease in cohesive force.

(2) By photopolymerizing or photocrosslinking the molecules of the adhesive and losing the adhesive properties of the adhesive, the adhesive force at the interface between the adhesive and the adhered object is reduced.

Particularly when separating the adhesive from the adhered object, if the adhesive is hardened, stress will be concentrated at the interface, making peeling easier.

In the present invention, any of the above methods can be used (2
) method is more practical.

Such a mechanism is made possible by adding a photoinitiator to the adhesive beforehand and incorporating a photopolymerizable molecular moiety into the adhesive molecule design.

For example, the following has been proposed as an adhesive composition capable of reducing tackiness due to light, as described in PCT WO81100309. That is, a glycidyl methacrylate and isooctyl acrylate copolymer containing an oxirane ring was used as an adhesive, and φ3SSb was used as a photoinitiator.
A mixture φC1 of F6:φ2ssbF6φSφ:φ2SSbF6 (45:50:5 weight ratio) is added to the former in a weight ratio of 97:3. When the substance is exposed to ultraviolet light, the oxirane rings in the adhesive are polymerized, the adhesive is hardened, and the adhesive is reduced. When this pressure-sensitive adhesive is used, the peeling force on a glass surface is, for example, 800 g/cm before exposure, but decreases to 1 to 10 g/cm after exposure.

The adhesive strength can be adjusted by changing the copolymerization ratio of glycidyl methacrylate and isooctyl acrylate, or by blending other polymers. The adhesive having the composition adjusted in this manner and containing a photopolymerization initiator is dissolved in a solvent such as ethynope methyl ethyl ketone acetate or methylene chloride to a solid content concentration of 10 to 50%, and this is used as a coating solution. Apply to the back of the printing plate. At this time, if the back surface of the printing plate is slightly roughened, the adhesive will adhere well.

Furthermore, even when the adhesiveness is reduced due to photopolymerization and stress is concentrated at the interface during peeling, peeling occurs not at the support (for example, aluminum)/adhesive interface but at the adhesive/plate cylinder interface due to stress relaxation by the rough surface. Therefore, the plate material can be removed from the plate cylinder without leaving any adhesive behind.

Such phototack-reducing adhesives are used in various adhesive tapes. For example, FSK@3's D-203 is a 65 μm thick polyester tape that has a weight of 2400 g/g before UV light irradiation.
It is designed to have an adhesive force of 25 mm and 30 g/25 mm after irradiation, and various types have been obtained by designing the composition of the adhesive.

Therefore, the adhesive composition can be designed within a wide range depending on the material and thickness of the plate material used, and the required adhesion or adhesive strength. However, since the adhesive will harden or disintegrate when exposed to light, the adhesive must have good transparency, and therefore it is not desirable to use fillers to increase adhesive strength.

As an example, when the above adhesive was applied to the back of a lithographic printing plate using 30 μm aluminum foil and adhered to a hard glass plate cylinder, the peel resistance was about 1000 g/cm, but after exposure to ultraviolet light The weight was 30 g/cm, and peeling was easily performed.

On the other hand, when applying the adhesive to the back side of a lithographic printing plate, it is also possible to put the adhesive in microcapsules and apply it to the back side. In this case, there is no need for an adhesive layer protective sheet, and there is no need to remove the protective sheet prior to printing. However, it is assumed that the microcapsules are not destroyed or destroyed by the developer during the pre-printing process.

Microencapsulation of the glycidyl nucleate/isooctyl acrylate copolymer and the photoinitiator added thereto can be carried out, for example, as described in US Pat. No. 2,800,457. The method will be described below.

4 parts of acid-treated pork skin gelatin and 10 parts of gum arabic
Dissolved in 400 parts of water at 0°C and added 0.0 parts of funnel oil as an emulsifier.
2 parts, and 40 parts of adhesive oil is emulsified and dispersed therein.

Adhesive oil is 32 parts of toluene and Aiyoku/Aibon R3-6.
71 [Manufactured by Aikani Gyo ■, 98 parts of SBR synthetic rubber was dissolved.

When the size of the oil droplets reaches an average of 10 μm, emulsification is stopped, and water at 40° C. is added to make a total volume of 900 parts, and stirring is continued. Then, 10% acetic acid was added to adjust the pH of the solution to 4.
0 to 4.2 to cause coacervation. After 20 minutes of continued stirring, the mixture is cooled with ice water to gel the coacervate film deposited around the oil droplets. When the liquid temperature reaches 20°C, add 7 parts of 37% formalin. When the liquid temperature reaches 10°C, a 15% aqueous solution of caustic soda is added to adjust the pH to 9. Subsequently, the mixture was heated for 30 minutes while stirring to bring the liquid temperature to 40°C. In this way, microcapsules were obtained. Next, 15 parts of a 1:1 mixture of polyvinyl alcohol and oxidized starch was added as a binder and stirred to prepare a coating solution.

The weight of the above coating solution after drying on the back side of the planographic support is IQg/
It was coated and dried so that it became m'.

The capsules on the back surface of the plate thus obtained are destroyed by increasing the contact pressure between the plate cylinder and the blanket cylinder of the printing press and installing the plate on the plate cylinder, causing the plate to adhere to the plate cylinder. At this time, the plate can be held on the plate cylinder by the conventional gripping method of a printing press.

In addition to the above phase separation method, encapsulation is carried out using an interfacial polymerization method such as 3 parts of 1-phenyl-1-xylylethane as an oily solvent, 0.7 parts of an adduct of tolylene diisocyanate and trimethylolpropane (3:1), and as necessary. It is also possible, if appropriate, to carry out the encapsulation using 0.2 part of propylene oxide (1; 4) adduct of ethylenediamine.

The particle size of the microcapsules used in the present invention is 0.1~
400μ, preferably in the range of 5 to 100μ. The thickness of the wall film is preferably in the range of 0.01 to 50μ, and the strength of the microcapsule is preferably in the range of 0.001 to 1.0 dyne/c++t. In general, when the particle size of microcapsules is increased and the wall membrane is thinned, it becomes easier to collapse due to mechanical pressure, which is convenient for the purpose of the present invention, but at the same time, the wall membrane becomes difficult to maintain during transportation, plate making, etc. There is an inconvenience that the substance will disintegrate and be discharged. On the other hand, if the particle size is made smaller, the opposite disadvantage occurs.

This invention will be described in detail below with reference to FIG.

(1) How to attach the plate material to the printing press The present inventor has conducted various studies on how to attach the thin plate material to the plate cylinder, and the most practical method is to apply an adhesive to the back side of the plate in advance. I found that. Even if adhesive is applied to the back side of the plate, if a protective film is used, the photosensitive planographic printing plate can be coiled and supplied to the plate making department, and the planographic printing plate obtained here is continuously sent to the printing machine. be able to. Furthermore, by providing a device on the front of the printing press that can peel off the protective film and cut the plate material, even thin plate materials can be easily wound around the plate cylinder. In fact, as schematically shown in FIG. 1, the plate material 5 is attached to the groove 2 of the plate cylinder 1 of the printing press using the jig holding part 10 and the wedge-shaped jig 9, and the blanket cylinder If the printing press is rotated slowly while making contact with the plate, the plate will be firmly attached to the plate cylinder 1 by the adhesive 6 on the back side of the plate. Thereafter, by operating the cutter section 3, the plate is separated from the plate material coil body. The ends of the separated plate material are fixed in the grooves 2' of the plate cylinder 1 using the same jig holding part 10 as described above and a wedge-shaped jig 9'. In this case, by pushing up the lower part of the jig holding part 10, the back surface of the plate material is
′ will easily stick to the grooves 2 and 2′.
It should be fixed to .

The remaining separated portion is held in that position by a holding roll 4 after the cutter 3 until the next printing.

Further, the protective sheet 7 for protecting the adhesive portion is peeled off from the adhesive just before the pressure roll 4 and is wound up by a winder 8. Therefore, for the next printing, it is only necessary to attach the end surface of the plate material to the groove 2 of the plate cylinder l without peeling off the protective sheet 7 of the adhesive layer one by one.

(2) Method of fixing the edge of the plate material to the groove of the plate cylinder When attaching the edge of the plate material to the groove 2, use wedge-shaped jigs 9 and 9', and apply an adhesive layer on the back side. The plate material 5 having the plate material 5 is pasted and fitted into the grooves 2 and 2' of the plate cylinder 1 in a wedge shape.

The jig also needs to be transparent so that the edges of the plate material adhered to the jig can be peeled off from the jig.

(3) How to remove the protective film of the adhesive layer The protective film 7 provided to prevent the adhesive layer and the photosensitive layer from adhering is removed as shown in Figure 1 before mounting the plate on the plate cylinder of the printing press. It is peeled off like this. Specifically, the end portion of the protective film 7 may be attached to the film take-up roll 8, and the plate may be mounted while synchronizing the roller and the plate cylinder 1. After that, the protective film 7 is automatically peeled off without attaching the protective film 7 to the take-up roller 8, and the plate 5
can be adhered to the plate cylinder 1.

(4) Method for attaching and removing the plate material after printing from the printing press The plate body of the printing press used in the present invention is made of a transparent material, for example, hard glass, and an ultraviolet light source such as an air-cooled mercury lamp is provided inside. Transparent polymers such as acrylic resins may be used instead of glass, and the part of the plate cylinder where the back surface of the plate material is covered with roses may be transparent, and the other parts may have mechanical strength.
Furthermore, there is no problem even if steel parts are used for interlocking with other parts.

The ultraviolet light source may be installed inside the plate cylinder, but it may also be inserted into the plate cylinder from the outside when necessary, or the light may be input using a reflected optical path.

This is easier in terms of plate cylinder design.

When UV light is used as a light source, a certain amount of illuminance or more is required to cause a decrease in phototackiness.

Although its value is determined experimentally, a sufficient effect is often obtained with 100 W or more. When handling plates in a bright room, the adhesive applied to the back side may be exposed to light from, for example, a fluorescent light, and this value should be increased if there is a risk that the adhesive strength of the adhesive may decrease when attaching the plate to the plate cylinder. It is also possible on a prescription basis.

(5) Method for manufacturing planographic plates with adhesive applied to the back side Thickness 1-
A thin aluminum material of approximately 0 μm is used, and its surface is roughened in the same manner as a support for a normal PS plate, and the back surface is slightly roughened to an average roughness Ha of approximately 0.2 μm at the same time or in a separate process. If necessary, the aluminum material is anodized and hydrophilized, and a photosensitive layer is applied to the surface, and a photocurable adhesive is applied to the back. 3. The aluminum material is continuously processed using a coiled material, and the photosensitive layer and support are coated. To prevent adhesion with the adhesive on the back side, a protective film similar to the release sheet for regular adhesive tapes is used, and the product is rolled up.

For example, PCTW○ 8, which was mentioned earlier, is a photo-curable adhesive.
Glycidyl methacrylate/isooctyl acrylate (25 near 5 weight ratio) shown in 110 O309
Copolymer, as a photoinitiator, and as a photoinitiator, φ3SSbF6:φ2ssbF6:φ2ssbF6φS
A mixture of φCβ (45:50:5 weight ratio) was added to the former at a weight ratio of 97:3.

It was dissolved in methyl ethyl ketone to a solid content of 25% and applied to the back side of an aluminum foil PS plate. In this case, by slightly roughening the back side of the aluminum foil to make it an adhesive surface, the adhesive will strongly adhere to the aluminum side.

The dry coating weight may be about 5 g/m'.

The release paper, that is, the protective film for the adhesive, is a plastic film coated with a silicone release agent (100 μm thick).
) can be used.

Plate materials having such a configuration can be semi-continuously plate-made and conveyed directly to the printing press if the exposure and development devices are devised. Since the exposure and development processes are carried out with a protective film present, even if a foil material of about 10 μm is used for the aluminum material, problems such as cutting of the aluminum material and generation of wrinkles will not occur. On the other hand, during printing, the protective film of the plate material is peeled off, but since the plate is fixed on the plate cylinder by an adhesive, there is no problem with printing even if aluminum foil is used as a support.

In addition, such a plate material is adhesively fixed to a hard glass plate making cylinder.
The elongation of the printing plate after printing 10,000 sheets is 1% or less, and it is possible to prevent the plate from cutting, which occurs when no adhesive is used.

Example An aluminum material with a thickness of 10 μm was roughened to an average surface roughness of 0.5 μm on the surface and 0.2 μm on the back surface by electrolytic graining in an aqueous nitric acid solution in the same way as a support for a normal PS plate. After oxidation, a hydrophilic treatment was performed using a No. 3 sodium silicate (silicate) bath. A negative photosensitive layer using a diazonium compound was applied to the surface of this aluminum material, and a photocurable adhesive was applied to the back surface. As an adhesive,
glycidyl methacrylate/isooctyl acrylate)
'(20/80 weight ratio) To 97 parts of copolymer, photoinitiator (φ3SSbF6/φ2ssbFs/φ2ssbFs (4515015
A solution prepared by dissolving 3 parts of 25% solids in methyl ethyl ketone was used. The aluminum material is continuously processed using a coiled material, and a 100 μm thick protective film (the polyethylene surface is made hydrophilic and a silane coupling agent is applied) to prevent adhesion between the photosensitive layer and the adhesive on the back of the support. (coated with the used silicone mold release agent) was laminated on the adhesive layer and wound up. The amount of adhesive applied was 5 g/m' (dry weight).

After exposing and developing this photosensitive printing plate with a protective film attached, it was mounted on a hard glass plate cylinder as shown in FIG. 1, and printing was performed. The elongation of the printing plate after printing 10,000 sheets was 1% or less, and it was possible to completely prevent the plate from cutting, which occurs when no adhesive is used.

After printing was completed, the adhesive layer was irradiated from inside the printing cylinder for about 1 minute using a high-pressure mercury lamp (air-cooled type, 100 W) while rotating the printing cylinder with a diameter of 200 mm.

The tackiness was reduced and the printing plate could be easily peeled off from the plate cylinder.

(Effects of the Invention) The present invention, which allows a thin foil-like plate material to be easily attached to and removed from the plate cylinder of a printing press, makes it possible to continuously and automatically supply the plate material in the form of a coil to the plate-making and printing departments, and is lightweight. Demonstrates excellent effects in printing automation and labor saving.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a printing machine suitably used to carry out the method of the present invention and a section for conveying plate material to the printing machine. Procedural amendment 63.3.22 Showa year, month, day 1, case description 1988 Patent Application No. 36394 2, title of invention Lithographic printing method and lithographic printing plate 3
, Relationship with the person making the amendment Applicant name (520) Fuji Photo Film Co., Ltd. 4, Agent 5, Date of amendment order Initiator 6, Subject of amendment Column 1 for detailed explanation of the invention in the specification, Specification On page 10 of the book, line 3, insert ``sex'' after the word ``transformed adhesive''. 2. In the same book, page 22, line 7, "diameter medicine" is corrected to "diameter". 3. On the same page of the same book, line 9, ``The tackiness of the printing plate decreases,''
is corrected to ``The tackiness of the printing plate decreases.''

Claims (3)

[Claims] (1) A lithographic printing method characterized by printing by fixing a lithographic printing plate to a transparent plate cylinder using a light-peelable adhesive. (2) A lithographic printing plate characterized by having a light-peelable adhesive layer provided on the back surface. (3) After the printing described in claim (1) is completed, light is irradiated to the back side of the planographic printing plate through the transparent plate cylinder surface to reduce the adhesiveness of the light-peelable adhesive and detach the planographic printing plate from the plate cylinder. A lithographic printing method characterized by: