JP2023137275A - laminate - Google Patents

Abstract

To provide a laminate capable of reducing an impression of a surface of a silicone rubber layer of a waterless lithographic printing plate original plate or a waterless lithographic printing plate even if the silicone rubber layer has a large thickness.SOLUTION: A laminate has, on a support, a waterless lithographic printing plate original plate or a waterless lithographic printing plate including a silicone rubber layer having at least a thickness of 2.2 μm or more, and a cushioning material. The cushioning material is disposed on at least a side of the silicone rubber layer of the waterless lithographic printing plate original plate or the waterless lithographic printing plate.SELECTED DRAWING: None

Description

The present invention relates to a laminate of a waterless lithographic printing plate precursor or a waterless lithographic printing plate and a cushioning material.

Curved surface printing on the body of two-piece cans used for beverage cans, aerosol cans, and cylindrical containers such as tubes requires a printing plate and an ink layer that is received from the printing plate and applied to the can body. A combination with a blanket for transfer is used, and the printing plate is mainly a resin letterpress or lithographic plate. Traditionally, in two-piece can printing, the printing method using resin letterpress, in other words, the letterpress dry offset method, has been the mainstream.However, with conventional resin letterpress, the lines and halftone dots tend to get thicker, so characters and halftone dot images are difficult to print. In can printing, the AM screen frequency of halftone dots is low at around 120 lines/inch, and striped patterns and rosette patterns due to roughness of the halftone dot image and interference between halftone dots are easily noticeable. It was difficult to obtain sufficient print quality.

In recent years, due to the market environment in which high-definition, highly decorated beverage cans are required, waterless lithographic plates and waterless lithographic printing plate precursors for can printing that are high-definition and have excellent printing durability are being considered. For example, it has at least a substrate and a laser heat-sensitive layer, and a non-image area and an image area made of a silicone rubber layer are formed on the heat-sensitive layer, and the thickness of the silicone rubber layer in the non-image area is 2.2. A waterless planographic printing plate for seamless cans characterized by a thickness in the range of ~5.5 μm (for example, see Patent Document 1), and a substrate having at least a heat-sensitive layer and a silicone rubber layer, and the substrate is a ferromagnetic material. Waterless lithographic printing plate precursors (for example, see Patent Document 2) have been proposed.

On the other hand, as a technique for suppressing damage to the plate edges that occurs during transportation of a waterless lithographic printing plate precursor laminate, a waterless lithographic printing plate precursor having at least a photosensitive layer or a heat sensitive layer and a silicone rubber layer on a substrate, A waterless lithographic printing plate precursor laminate (for example, see Patent Document 3) has been proposed, which is formed by laminating a lithographic printing plate precursor insert paper whose surface is textured.

JP 2018-58257 Publication International Publication No. 2020/256059 Japanese Patent Application Publication No. 2008-55814

The waterless lithographic printing plate precursors described in Patent Documents 1 and 2 have thick silicone rubber layers in order to improve printing durability. The inventors have found that when the thickness of the flexible silicone rubber layer is large, when localized pressure is applied to the surface of the waterless lithographic printing plate precursor or waterless lithographic printing plate due to biting of foreign matter, the silicone rubber layer It was found that the problem of easy formation of uneven marks (press marks) on the surface of the rubber layer became noticeable. In particular, when transporting waterless planographic printing plate precursors or storing waterless planographic printing plates, when multiple waterless planographic printing plate precursors or waterless planographic printing plates are stacked, the water layered on top Due to the weight of the waterless lithographic printing plate precursor or waterless lithographic printing plate, the problem of imprint marks becomes more noticeable in the lower layer waterless lithographic printing plate precursor or waterless lithographic printing plate. Although the paper for lithographic printing plate precursor described in Patent Document 3 can suppress damage such as bending and folding of the edge of the plate that occurs during transportation, it is difficult to prevent damage such as bending and folding of plate edges that occur during transportation. The problem with the lithographic printing plate without the silicone rubber layer was that it was still prone to press marks on the surface of the silicone rubber layer.

Therefore, an object of the present invention is to provide a laminate that can suppress press marks on the surface of the silicone rubber layer of a waterless lithographic printing plate precursor or a waterless lithographic printing plate even when the silicone rubber layer is thick. .

In order to solve the above problems, the present invention mainly has the following configuration.
A laminate of a waterless lithographic printing plate precursor or waterless lithographic printing plate having a silicone rubber layer with a thickness of at least 2.2 μm on a support and a buffer material, the waterless lithographic printing plate precursor or waterless lithographic printing plate precursor having a thickness of at least 2.2 μm or more on a support. A laminate having a cushioning material on at least the silicone rubber layer side of a lithographic printing plate.

The laminate of the present invention can suppress press marks on the surface of the silicone rubber layer of a waterless lithographic printing plate precursor or a waterless lithographic printing plate even when the silicone rubber layer is thick.

Hereinafter, details of implementation of the present invention will be explained.

The laminate of the present invention is a laminate of a waterless lithographic printing plate precursor or a waterless lithographic printing plate having a silicone rubber layer with a thickness of at least 2.2 μm on a support, and a buffer material, the laminate comprising at least a silicone rubber layer. It has a cushioning material on the layer side. A waterless lithographic printing plate precursor (hereinafter sometimes abbreviated as a "printing plate precursor") is a waterless lithographic printing plate (hereinafter sometimes abbreviated as a "printing plate") with an inked area (image line). This is a precursor before forming the ink-repelling portion (non-printing portion) and the ink-repelling portion (non-printing portion). The support has a function of retaining the shape of the printing plate precursor or printing plate, and the silicone rubber layer has a function of repelling ink and forms a non-image area of the printing plate. For printing plate precursors and printing plates that have a silicone rubber layer with a thickness of 2.2 μm or more that tends to cause push marks, the cushioning material is made of foreign matter that can cause push marks on the silicone rubber layer on the silicone rubber layer side. In contrast, it has the function of relaxing stress by deforming itself and suppressing pressure marks on the silicone rubber layer.

The laminate of the present invention may include one printing plate precursor or printing plate and one cushioning material, or may be a multilayer laminate in which a plurality of sets of these are further laminated. Furthermore, one printing plate precursor or printing plate may have a cushioning material on both sides of the silicone rubber layer side and the support side, or two printing plate precursors may be provided on both sides of one cushioning material. Alternatively, the printing plates may be stacked with the silicone rubber layer facing the cushioning material side. From the viewpoint of workability, the adhesion between the cushioning material and the printing plate precursor or printing plate is preferably such that it can be easily peeled off manually.

(buffer material)
The cushioning material in the present invention refers to one having an Asker C hardness of 60 degrees or less. Asker C hardness is an index of the hardness of soft foams such as sponges, and can be measured using a commercially available durometer hardness meter. For example, a sample having a thickness of 1.0 mm or more can be measured using a durometer hardness meter GS-701 (manufactured by Techrock Co., Ltd.) in an environment with a temperature of 25° C.±5° C. When the thickness of the cushioning material is less than 1.0 mm, it is laminated to a thickness of 1.0 mm or more and then measured. Specifically, in an environment with a temperature of 25°C ± 5°C, a cushioning material with a thickness of 1.0 mm or more is prepared, placed on a flat glass plate, and then a durometer hardness tester is slowly inserted vertically from above. Press the durometer hardness meter and read the indicated value within 1 second after the pressure surface of the durometer comes into contact with the object to be measured. This measurement is performed at three randomly selected locations, and the average value is defined as the Asker C hardness.

Materials with an Asker C hardness of more than 60 degrees do not fall under the category of cushioning material in the present invention, and press marks are likely to occur when localized pressure is applied to the surface of the printing plate precursor or printing plate due to foreign matter being bitten. . The Asker C hardness of the cushioning material is preferably 50 degrees or less, more preferably 30 degrees or less.

Examples of cushioning materials include foamed sheets such as urethane foam, phenol foam, polyethylene foam, polypropylene foam, ethylene/vinyl alcohol copolymer (EVA) foam, and polystyrene foam, hollow structured sheets such as air caps, and silicone rubber. Examples include gelatinized sheets such as, and structures in which fibrous polyethylene resin is formed into a three-dimensional network. Two or more types of these may be used. Among these, a foamed sheet made of polyethylene foam is preferred because it is inexpensive, stably available, and has both flexibility and strength. Examples of such foam sheets include "Torepef" (registered trademark) 15060AA00, 10020AA00, 10040AA00, 15020AA00, 15030AA00, 15040AA00, 20040AA00, 30030AG00, 30050AG00, 30100AG00, 4 0100AG00, 30040AS60, 30040AY00, 30020BY00, 40080AY00 (Toray Industries, Inc. ), “Lytron” (registered trademark) S#41, #52, #54, #56, #58, #510, #512 (manufactured by Sekisui Plastics Co., Ltd.), “Softron” (registered trademark) Trademark) S (manufactured by Sekisui Chemical Co., Ltd.), "Volara" (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), "XLIM" (registered trademark) (manufactured by Sekisui Chemical Co., Ltd.), "Minaform" (registered trademark) (manufactured by Sakai Chemical Industry Co., Ltd.), “Sunperca” (registered trademark) L-600, L-900, L-1000, L-1001NN, L-1002, L-1100, L-1400, L -1500, L-2000, L-2500, L-2501NNN, L-2521NN, L-4000, L-4000NN, SL-3000 (manufactured by Sanwa Kako Co., Ltd.), “Opcel” (registered trademark) LC-150 , LC-150S, LC-300#1, LC-300#2D, LC-300#2WE, LR-300#2 (manufactured by Sanwa Kako Co., Ltd.).

The thickness of the cushioning material in the present invention is preferably 0.1 mm or more from the viewpoint of further suppressing press marks on the surface of the silicone rubber layer. On the other hand, the thickness of the cushioning material is preferably 3.0 mm or less, more preferably 1.0 mm or less, from the viewpoint of improving the storage efficiency and transportation efficiency of the laminate.

Here, the thickness of the cushioning material can be measured using a thickness gauge. As the thickness gauge, one with a minimum display value of 0.01 mm or less and a measuring force of 3.5 N or less is used. The thickness was measured at five randomly selected locations under a measurement environment of 25° C.±5° C., and the average value was taken as the thickness.

(Original printing plate)
The printing plate precursor has a silicone rubber layer with a thickness of at least 2.2 μm or more on a support. A photosensitive layer and/or a heat-sensitive layer may be further provided between the support and the silicone rubber layer, and the silicone rubber layer can be partially removed to form an inked area (image area). . At least the surface of the photosensitive layer or heat-sensitive layer is decomposed by the light irradiated or the heat generated by pattern exposure, or the solubility in the developer increases, or the adhesive strength with the silicone rubber layer decreases. It is preferable that there be. As described above, the silicone rubber layer has the function of repelling ink, and the portion where the silicone rubber layer remains forms an ink repelling portion (non-printing portion). Furthermore, the support may have a primer layer that improves adhesion with the upper layer, and the silicone rubber layer may have a protective film and/or interleaving paper that protects the silicone rubber layer. . As a printing plate precursor having a heat-sensitive layer and a silicone rubber layer on a support, printing plate precursors described in JP 2018-58257A and WO 2020/256059 are preferred.

The thickness of the silicone rubber layer of the printing plate precursor is 2.2 μm or more. As mentioned above, the thicker the silicone rubber layer, the better the printing durability, but there was a problem in that the surface of the silicone rubber layer was more likely to have press marks. According to the present invention, even when the silicone rubber layer is thick, it is possible to suppress press marks on the surface of the silicone rubber layer. Since the effects of the present invention are significantly exhibited when the silicone rubber layer is thick, the thickness of the silicone rubber layer is preferably 2.5 μm or more, more preferably 3.0 μm or more. On the other hand, from the viewpoint of high-definition image reproducibility, the thickness of the silicone rubber layer is preferably 10.0 μm or less, more preferably 8.0 μm or less. Here, the thickness of the silicone rubber layer can be determined by observation using a transmission electron microscope (TEM). More specifically, a sample is prepared from a printing plate precursor by an ultra-thin section method, and a vertical section of the printing plate precursor is subjected to TEM observation at an acceleration voltage of 100 kV and a magnification of 2,000 times. In the obtained TEM observation image, the thickness was measured at 10 randomly selected locations from the silicone rubber layer, and the average value was taken as the thickness.

Examples of the support for the lithographic printing plate precursor include paper, metal plates, glass plates, and plastic films. Examples of the metal plate include metal sheets containing aluminum, iron, cobalt, nickel, alloys thereof, and/or oxides thereof. Examples of the plastic film include plastic films such as polyethylene terephthalate and polyethylene naphthalate. Supports for two-piece can printing include plate cylinders that are fixed using magnets, such as two-piece can printing machines such as Concord type printing presses and Rutherford type printing presses (both manufactured by Stolle Machinery Company). In consideration of installation in a printing machine with specifications, it is preferable to use a material made of ferromagnetic material such as iron, cobalt, nickel, alloys or oxides thereof. These ferromagnetic materials have a higher specific gravity than aluminum, which is widely used in conventional printing plates, and are heavier even if the thickness is the same. For this reason, when a plurality of printing plate precursors having these supports are stacked, the lower layer printing plate precursor is greatly influenced by the weight of the upper layer printing plate precursor, and tends to be susceptible to impression marks. In the present invention, the effect of suppressing push marks by the cushioning material is more pronounced.

Examples of the method for manufacturing the printing plate precursor include the method described in International Publication No. 2020/256059.

(Print version)
The printing plate has a silicone rubber layer with a thickness of at least 2.2 μm on the support. It is preferable to use the above-mentioned printing plate precursor as a precursor to form an ink-applied area (image area) and an ink-repellent area (non-image area) consisting of a silicone rubber layer. Preferred embodiments of the silicone rubber layer, etc. This is the same as the preferred embodiment of the printing plate precursor described above. A printing plate obtained from a printing plate precursor having a heat-sensitive layer and a silicone rubber layer on a support is preferable, and, for example, printing plates described in JP 2018-58257A and WO 2020/256059 are preferable.

As a method for manufacturing a lithographic printing plate, for example, a coating liquid for a silicone rubber layer is discharged onto an ink-receptive support using an inkjet head, dried, and an ink-repellent area (non-image area) is formed. By using a method of forming a silicone rubber layer on a support, or by using a printing plate precursor having a heat-sensitive layer and a silicone rubber layer in this order on a support, the ink-applied area (image area) is Examples include a method of removing the silicone rubber layer. The latter method preferably includes the following steps (1) and (2).
Step (1): Exposure step of irradiating the printing plate precursor with a laser Step (2): After step (1), the ink-applied area (image) is removed by removing the silicone rubber layer in the laser-irradiated area. Development process for forming line portions) Examples of the method for producing a lithographic printing plate including the above steps (1) and (2) include the method described in International Publication No. 2020/256059.

(Method for manufacturing laminate)
Methods for manufacturing the laminate of the present invention include, for example, cutting a printing plate precursor or printing plate into a predetermined size and then placing a cushioning material on the silicone rubber layer side; A method of placing a cushioning material on the side and cutting it to a predetermined size as necessary.A method of supplying a cushioning material in a roll form to the printing plate precursor or printing plate supplied in a roll form and bringing it into close contact, and cutting it to a specified size as necessary. Examples include a method of cutting to a predetermined size. From the viewpoint of suppressing adhesion of cutting waste to the plate surface and further suppressing the occurrence of pressing marks, a method in which a printing plate precursor or a printing plate and a cushioning material are laminated and then the laminated body is cut to a predetermined size. is preferred.

Hereinafter, the present invention will be specifically explained with reference to Examples.

<Production Example 1: Production of waterless lithographic printing plate precursor 1>
The following primer layer composition solution was applied onto a degreased aluminum substrate (alloy number 1050, temper: H18, manufactured by Mitsubishi Aluminum Co., Ltd.) with a thickness of 0.24 mm, and dried at 200°C for 90 seconds. A 6.0 μm primer layer was provided. The primer layer composition solution was obtained by stirring and mixing the following components at room temperature.

<Primer layer composition solution>
Epoxy resin: “jER” (registered trademark) 1010 (manufactured by Mitsubishi Chemical Corporation): 35 parts by mass Polyurethane: “Samplen” (registered trademark) LQ-T1331D (manufactured by Sanyo Chemical Industries, Ltd., solid content concentration: 20 mass) %) 375 parts by mass Aluminum chelate: Aluminum chelate ALCH-TR (manufactured by Kawaken Fine Chemicals Co., Ltd.): 10 parts by mass Leveling agent: “Disparon” (registered trademark) LC951 (Kusumoto Kasei Co., Ltd., solid content: 10% by mass) ): 1 part by mass Titanium oxide: N,N dimethylformamide dispersion of "Tiepeque" (registered trademark) CR-50 (manufactured by Ishihara Sangyo Co., Ltd.) (titanium oxide 50% by mass): 60 parts by mass N,N-dimethyl Formamide: 730 parts by mass Methyl ethyl ketone: 250 parts by mass.

Next, the following heat-sensitive layer composition solution was applied onto the primer layer and dried by heating at 140° C. for 90 seconds to form a heat-sensitive layer having a thickness of 1.4 μm. The heat-sensitive layer composition solution was obtained by stirring and mixing the following components at room temperature.

<Thermosensitive layer composition solution>
Infrared absorbing dye: "PROJET" 825LDI (manufactured by Avecia): 20 parts by mass Organic complex compound: titanium-n-butoxide bis(acetylacetonate): "Nasem" (registered trademark) titanium (manufactured by Nihon Kagaku Sangyo Co., Ltd., Concentration: 73% by mass, containing 27% by mass of n-butanol as a solvent): 25 parts by mass Phenol formaldehyde Novolac resin: "Sumilight Resin" (registered trademark) PR53195 (manufactured by Sumitomo Bakelite Co., Ltd.): 88 parts by mass Polyurethane : "Samplen" (registered trademark) LQ-T1331D (manufactured by Sanyo Chemical Industries, Ltd., solid content concentration: 20% by mass): 25 parts by mass Tetrahydrofuran: 480 parts by mass Diethylene glycol monomethyl ether: 150 parts by mass Ethanol: 180 parts by mass.

Next, the following silicone rubber layer composition solution prepared immediately before coating was coated on the heat-sensitive layer and heated at 140° C. for 80 seconds to form a silicone rubber layer with a thickness of 3.6 μm. The silicone rubber layer composition solution was obtained by stirring and mixing the following components at room temperature.

<Silicone layer composition solution>
α,ω-dihydroxypolydimethylsiloxane: DMS-S51 (weight average molecular weight 139,000, manufactured by GELEST Inc.): 100 parts by mass Tetrakis(methylethylketoximino)silane: 12 parts by mass Vinyl tris(methylethylketoximino)silane: 3. 0 parts by mass Dibutyltin acetate: 0.030 parts by mass Isoparaffinic hydrocarbon solvent "Isopar" (registered trademark) E (manufactured by Esso Chemical Co., Ltd.): 900 parts by mass.

Next, a 6.5 μm thick polypropylene film “Torefane” (registered trademark) (manufactured by Toray Industries, Inc.) was laminated as a cover film using a calendar roller to obtain a waterless lithographic printing plate precursor 1.

<Production Example 2: Production of waterless lithographic printing plate precursor 2>
The degreased aluminum substrate with a thickness of 0.24 mm was changed to an iron substrate "High Top" (registered trademark) T-4CA (manufactured by Toyo Kohan Co., Ltd.), the drying time of the primer layer was 120 seconds, and the heat-sensitive layer was Waterless lithographic printing plate precursor 2 was obtained in the same manner as in Production Example 1 except that the drying time was changed to 120 seconds and the drying time of the silicone layer was changed to 110 seconds.

<Production Example 3: Production of waterless lithographic printing plate 1>
The waterless lithographic printing plate precursor 1 obtained in Production Example 1 was treated with CP-X (manufactured by Toray Industries, Inc.) as a pre-treatment liquid, tap water as a developer, and PA-1 (manufactured by Toray Industries, Inc.) as a post-treatment liquid. ) and passed through an automatic processor TWL-1160F (manufactured by Toray Industries, Inc.) at a speed of 30 cm/min to obtain waterless lithographic printing plate 1. In this production example, no exposure step was performed.

Evaluation in each Example and Comparative Example was performed by the following method.

<Asker C hardness>
In an environment with a temperature of 25°C ± 5°C, the cushioning materials used in each example and the paper sheets used in each comparative example were placed on a flat glass plate, and then a durometer hardness tester was slowly pressed vertically from above. The numerical value was read within 1 second after the pressure surface of the durometer hardness tester came into contact with the object to be measured. However, when the thickness of the cushioning material was less than 1.0 mm, measurements were made by laminating them so that the thickness was 1.0 mm or more. This measurement was performed at three randomly selected locations, and the average value was defined as the Asker C hardness.

<Thickness>
Under an environment with a temperature of 25°C ± 5°C, digital thickness gauge ID-C112XBSNo. 547-401 (manufactured by Mitutoyo Co., Ltd.), the thickness was measured at five randomly selected locations, and the average value was taken as the thickness.

<Silicone rubber layer thickness>
A sample was prepared from the printing plate precursor or printing plate used in each Example and Comparative Example by the ultra-thin section method, and the vertical section of the printing plate precursor was observed with a TEM at an acceleration voltage of 100 kV and a magnification of 2,000 times. Ta. In the obtained TEM observation image, the thickness was measured at 10 randomly selected locations from the silicone rubber layer, and the average value was calculated.

<Press mark evaluation>
The laminate obtained in each Example and Comparative Example was placed on a 1 mm thick glass plate with the cushioning material or interleaving paper facing upward, and placed on the cushioning material or interleaving paper to simulate a foreign object. A solder wire with a diameter of 0.5 mm and a length of 2.0 mm was placed. After pressurizing the solder wire at 0.02 MPa for 1 hour, the cushioning material or interleaf paper and cover film were peeled off, and using a stylus surface roughness meter SE1200 (manufactured by Kosaka Laboratory Co., Ltd.), The surface roughness was measured at a speed of 0.50 mm/sec and a measurement distance of 4.0 mm across the area where the solder wire was placed. When a dent of 1 μm or more was measured on the measurement profile, it was determined that there was a push mark, and when a dent of 1 μm or more was not observed, it was determined that there was no push mark.

[Example 1]
Polyethylene foam with an Asker C hardness of 23 degrees and a thickness of 2.6 mm was laminated as a cushioning material on the cover film side of the waterless planographic printing plate precursor 1 obtained in Production Example 1, and then cut into 10 cm x 10 cm to form a laminate. I got it. Table 1 shows the results evaluated by the method described above.

[Examples 2 to 4]
A laminate was obtained in the same manner as in Example 1, except that the waterless lithographic printing plate precursor and the buffer material were changed as shown in Table 1. Table 1 shows the results evaluated by the method described above.

[Example 5]
A laminate was obtained in the same manner as in Example 4, except that the waterless planographic printing plate precursor 2 was changed to the waterless planographic printing plate 1 obtained in Production Example 3. Table 1 shows the results evaluated by the method described above.

[Comparative example 1]
A laminate was obtained in the same manner as in Example 1, except that Kurupak-processed kraft paper (basis weight 73 g/m ² ) was laminated as interleaving paper instead of the cushioning material. Table 1 shows the results evaluated by the method described above.

[Comparative example 2]
A laminate was obtained in the same manner as in Example 1, except that high-quality paper (basis weight 52 g/m ² ) was laminated as interleaving paper instead of the cushioning material. Table 1 shows the results evaluated by the method described above.

Claims (4)

A laminate of a waterless lithographic printing plate precursor or waterless lithographic printing plate having a silicone rubber layer with a thickness of at least 2.2 μm on a support and a buffer material, the waterless lithographic printing plate precursor or waterless lithographic printing plate precursor having a thickness of at least 2.2 μm or more on a support. A laminate having a cushioning material on at least the silicone rubber layer side of a lithographic printing plate. The laminate according to claim 1, wherein the cushioning material has an Asker C hardness of 50 degrees or less. The laminate according to claim 1 or 2, wherein the thickness of the cushioning material is 0.1 mm or more and 3.0 mm or less. The laminate according to any one of claims 1 to 3, wherein the support contains iron, cobalt, nickel, an alloy thereof, and/or an oxide thereof.