WATER-DEVELOPABLE FLEXOGRAPHIC PRINTING PLATE PRECURSOR, FLEXOGRAPHIC PRINTING PLATE, AND PHOTOSENSITIVE RESIN COMPOSITION

Abstract

An object of the present invention is to provide a water-developable flexographic printing plate precursor which has excellent water developability and exhibits excellent printing durability in a case of being made into a flexographic printing plate, a flexographic printing plate, and a photosensitive resin composition. The water-developable flexographic printing plate precursor of the present invention includes a photosensitive layer, in which the photosensitive layer contains a monomer, a polymerization initiator, a base polymer, and water-dispersible particles, the water-dispersible particles have carbon-carbon double bonds, and an amount of the carbon-carbon double bonds on a surface of the water-dispersible particles is 21 or less.

Claims

1. A water-developable flexographic printing plate precursor comprising: a photosensitive layer, wherein the photosensitive layer contains a monomer, a polymerization initiator, a base polymer, and water-dispersible particles, the water-dispersible particles have carbon-carbon double bonds, and an amount of the carbon-carbon double bonds on a surface of the water-dispersible particles is 21 or less.

2. The water-developable flexographic printing plate precursor according to claim 1, wherein a glass transition temperature of a polymer constituting the water-dispersible particles is −52° C. or lower.

3. The water-developable flexographic printing plate precursor according to claim 1, wherein the water-dispersible particles are composed of at least one diene-based polymer selected from the group consisting of polybutadiene and a copolymer of an acrylic monomer or a methacrylic monomer with butadiene.

4. The water-developable flexographic printing plate precursor according to claim 3, wherein a molar ratio of the butadiene in the copolymer is 80 mol % or more.

5. A flexographic printing plate comprising: an image area; and a non-image area, wherein the image area is an image area obtained by imagewise exposing the photosensitive layer of the water-developable flexographic printing plate precursor according to claim 1, and developing the exposed photosensitive layer.

6. A photosensitive resin composition comprising: a monomer; a polymerization initiator; a base polymer; and water-dispersible particles, wherein the water-dispersible particles have carbon-carbon double bonds, and an amount of the carbon-carbon double bonds on a surface of the water-dispersible particles is 21 or less.

7. The photosensitive resin composition according to claim 6, wherein a glass transition temperature of a polymer constituting the water-dispersible particles is −52° C. or lower.

8. The photosensitive resin composition according to claim 6, wherein the water-dispersible particles are composed of at least one diene-based polymer selected from the group consisting of polybutadiene and a copolymer of an acrylic monomer or a methacrylic monomer with butadiene.

9. The photosensitive resin composition according to claim 8, wherein a molar ratio of the butadiene in the copolymer is 80 mol % or more.

10. The water-developable flexographic printing plate precursor according to claim 2, wherein the water-dispersible particles are composed of at least one diene-based polymer selected from the group consisting of polybutadiene and a copolymer of an acrylic monomer or a methacrylic monomer with butadiene.

11. The water-developable flexographic printing plate precursor according to claim 10, wherein a molar ratio of the butadiene in the copolymer is 80 mol% or more.

12. A flexographic printing plate comprising: an image area; and a non-image area, wherein the image area is an image area obtained by imagewise exposing the photosensitive layer of the water-developable flexographic printing plate precursor according to claim 2, and developing the exposed photosensitive layer.

13. The photosensitive resin composition according to claim 7, wherein the water-dispersible particles are composed of at least one diene-based polymer selected from the group consisting of polybutadiene and a copolymer of an acrylic monomer or a methacrylic monomer with butadiene.

14. The photosensitive resin composition according to claim 13, wherein a molar ratio of the butadiene in the copolymer is 80 mol% or more.

15. A flexographic printing plate comprising: an image area; and a non-image area, wherein the image area is an image area obtained by imagewise exposing the photosensitive layer of the water-developable flexographic printing plate precursor according to claim 3, and developing the exposed photosensitive layer.

16. A flexographic printing plate comprising: an image area; and a non-image area, wherein the image area is an image area obtained by imagewise exposing the photosensitive layer of the water-developable flexographic printing plate precursor according to claim 4, and developing the exposed photosensitive layer.

Description

EXAMPLES

[0154] Hereinafter, the present invention will be described in more detail with reference to examples. Materials, amounts used, ratios, treatment contents, treatment procedures, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

[0155] [Preparation of Synthetic Latex 1]

[0156] 465.0 g of water-dispersed latex (manufactured by Zeon Corporation, Nipol LX111NF, water-dispersed latex of polybutadiene, solid content: 55%) and 327.5 g of distilled water were added to a 1 L three-neck flask, and the temperature was raised to 75° C. with stirring under a nitrogen stream. After 30 minutes, an aqueous solution in which 4.9 g of 2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate (VA-057, manufactured by FUJIFILM Wako Chemicals Corporation) as a water-soluble azo polymerization initiator had been dissolved in 65.0 g of distilled water was added thereto at once. After 3 hours, the mixture was allowed to cool to room temperature (23° C.).

[0157] Next, the mixture was filtered through a non-woven filter paper (T-270, manufactured by ADVANTEC Co., Ltd.) to remove aggregates, thereby preparing a synthetic latex 1 having a concentration of solid contents of 30% by mass.

[0158] [Preparation of Synthetic Latex 2]

[0159] 465.0 g of water-dispersed latex (manufactured by Zeon Corporation, Nipol LX111NF, water-dispersed latex of polybutadiene, solid content: 55%) and 327.5 g of distilled water were added to a 1 L three-neck flask, and the temperature was raised to 75° C. with stirring under a nitrogen stream. After 30 minutes, an aqueous solution in which 4.9 g of 2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate (VA-057, manufactured by FUJIFILM Wako Chemicals Corporation) as a water-soluble azo polymerization initiator had been dissolved in 65.0 g of distilled water was added thereto at once. After 3 hours, the temperature was raised to 90° C., and after another 3 hours, the mixture was allowed to cool to room temperature (23° C.).

[0160] Next, the mixture was filtered through a non-woven filter paper (T-270, manufactured by ADVANTEC Co., Ltd.) to remove aggregates, thereby preparing a synthetic latex 2 having a concentration of solid contents of 30% by mass.

[0161] [Preparation of Synthetic Latex 3]

[0162] 465.0 g of water-dispersed latex (manufactured by Zeon Corporation, Nipol LX111NF, water-dispersed latex of polybutadiene, solid content: 55%) and 327.5 g of distilled water were added to a 1 L three-neck flask, and the temperature was raised to 75° C. with stirring under a nitrogen stream. After 30 minutes, an aqueous solution in which 4.9 g of 2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate (VA-057, manufactured by FUJIFILM Wako Chemicals Corporation) as a water-soluble azo polymerization initiator had been dissolved in 65.0 g of distilled water was added thereto at once. After 3 hours, the temperature was raised to 90° C., and after another 6 hours, the mixture was allowed to cool to room temperature (23° C.).

[0163] Next, the mixture was filtered through a non-woven filter paper (T-270, manufactured by ADVANTEC Co., Ltd.) to remove aggregates, thereby preparing a synthetic latex 3 having a concentration of solid contents of 30% by mass.

[0164] [Preparation of Synthetic Latex 4]

[0165] 465.0 g of water-dispersed latex (manufactured by Zeon Corporation, Nipol LX111NF, water-dispersed latex of polybutadiene, solid content: 55%) and 327.5 g of distilled water were added to a 1 L three-neck flask, and the temperature was raised to 75° C. with stirring under a nitrogen stream. After 30 minutes, an aqueous solution in which 9.6 g of 2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate (VA-057, manufactured by FUJIFILM Wako Chemicals Corporation) as a water-soluble azo polymerization initiator had been dissolved in 65.0 g of distilled water was added thereto at once. After 3 hours, the temperature was raised to 90° C., and after another 6 hours, the mixture was allowed to cool to room temperature (23° C.).

[0166] Next, the mixture was filtered through a non-woven filter paper (T-270, manufactured by ADVANTEC Co., Ltd.) to remove aggregates, thereby preparing a synthetic latex 4 having a concentration of solid contents of 30% by mass.

[0167] [Preparation of Synthetic Latex 5]

[0168] <Preparation of Polybutadiene Latex A>

[0169] In a pressure-resistant polymerizer, 200 parts by mass of deionized water, 0.03 parts by mass of tripotassium phosphate, 0.002 parts by mass of disodium ethylenediamine tetraacetate, 0.001 parts by mass of ferrous sulfate heptahydrate, and 2.00 parts by mass of sodium dodecylbenzenesulfonate were charged, and after sufficient nitrogen substitution with stirring to remove oxygen, 100 parts by mass of butadiene was added into the system and the temperature was raised to 50° C.

[0170] Thereafter, 0.03 parts by mass of cumene hydroperoxide and then 0.10 parts by mass of sodium formaldehyde sulfoxylate were added to the system, and the reaction was performed for 5 hours.

[0171] Thereafter, 160 parts by mass of additional butadiene was added to the system.

[0172] Thereafter, 0.02 parts by mass of cumene hydroperoxide and then 0.10 parts by mass of sodium formaldehyde sulfoxylate were added to the system, and the reaction was performed for 10 hours.

[0173] The residual monomer was devolatilized and removed under reduced pressure to complete the polymerization, thereby obtaining a polybutadiene latex A containing polybutadiene as a main component and having a concentration of solid contents of 55% by mass.

[0174] <Preparation of Synthetic Latex 5>

[0175] 465.0 g of the polybutadiene latex A prepared above and 327.5 g of distilled water were added to a 1 L three-neck flask, and the temperature was raised to 75° C. with stirring under a nitrogen stream. After 30 minutes, an aqueous solution in which 4.9 g of 2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate (VA-057, manufactured by FUJIFILM Wako Chemicals Corporation) as a water-soluble azo polymerization initiator had been dissolved in 65.0 g of distilled water was added thereto at once. After 3 hours, the temperature was raised to 90° C., and after another 6 hours, the mixture was allowed to cool to room temperature (23° C.).

[0176] Next, the mixture was filtered through a non-woven filter paper (T-270, manufactured by ADVANTEC Co., Ltd.) to remove aggregates, thereby preparing a synthetic latex 5 having a concentration of solid contents of 30% by mass.

[0177] [Preparation of Synthetic Latex 6]

[0178] 511.5 g of SB latex (manufactured by Asahi Kasei Co., Ltd., A-7137, water-dispersed latex of styrene-butadiene copolymer, solid content: 50% by mass) and 327.5 g of distilled water were added to a 1 L three-neck flask, and the temperature was raised to 75° C. with stirring under a nitrogen stream. After 30 minutes, an aqueous solution in which 4.9 g of 2,2′-azobis[N-(2-carboxyethyl)-2-methylpropionamidine]tetrahydrate (VA-057, manufactured by FUJIFILM Wako Chemicals Corporation) as a water-soluble azo polymerization initiator had been dissolved in 65.0 g of distilled water was added thereto at once. After 3 hours, the temperature was raised to 90° C., and after another 6 hours, the mixture was allowed to cool to room temperature (23° C.).

[0179] Next, the mixture was filtered through a non-woven filter paper (T-270, manufactured by ADVANTEC Co., Ltd.) to remove aggregates, thereby preparing a synthetic latex 6 having a concentration of solid contents of 30% by mass.

[0180] A part of the solid content (water-dispersible particles) contained in the prepared synthetic latex 1 to 6 and water-dispersed latex (manufactured by Zeon Corporation, Nipol LX111NF) was collected, and the surface C═C amount and the glass transition temperature were measured by the methods described above. The results are shown in Table 1 below.

TABLE-US-00001 TABLE 1 Water-dispersible particle Surface C═C amount Glass transition temperature Synthetic latex 1 21.0 −60° C. Synthetic latex 2 20.7 −60° C. Synthetic latex 3 20.3 −58° C. Synthetic latex 4 20.0 −58° C. Synthetic latex 5 20.0 −58° C. Synthetic latex 6 19.2 −50° C. Nipol LX111NF 21.4 −62° C.

Example 1

[0181] [Preparation of Photosensitive Resin Composition]

[0182] 183 parts by mass of the above-described synthetic latex 1 (solid content: 55 parts by mass) and 15 parts by mass of 1,9-nonanediol dimethacrylate (NK ESTER NOD-N, manufactured by Shin-Nakamura Chemical Co., Ltd.) were mixed, and moisture was evaporated for 6 hours in a dryer heated to 60° C. to obtain a mixture of water-dispersible particles and monomers.

[0183] The obtained mixture and 25 parts by mass of butadiene rubber [ASADENE (registered trademark) NF35R, manufactured by Asahi Kasei Co., Ltd.) were kneaded in a kneader set at 110° C. for 45 minutes.

[0184] Thereafter, 0.2 parts by mass of a thermal polymerization inhibitor and 4.8 parts by mass of a photopolymerization initiator Irgacure 651 (manufactured by BASF) were put into the kneader, and the mixture was kneaded for 5 minutes to obtain a photosensitive resin composition.

[0185] [Production of Laminate for Infrared Ablation Layer]

[0186] 812 parts by mass of methyl isobutyl ketone was added to a mixture of 50 parts by mass of acrylic resin (Hi-pearl M-5000, manufactured by Negami Chemical Industrial Co., Ltd.), 50 parts by mass of an elastomer (Nipol DN-101, manufactured by Zeon Corporation), and 100 parts by mass of carbon black (MA-8, manufactured by Mitsubishi Chemical Corporation), and the mixture was mixed with a stirring blade.

[0187] After dispersing the obtained mixed solution with a paint shaker, methyl isobutyl ketone was further added thereto so that the solid content was 15% by mass to obtain a polymer/carbon black dispersion liquid (coating solution for an infrared ablation layer).

[0188] Next, the coating solution for an infrared ablation layer was applied to one side of a PET film (cover film) having a thickness of 75 μm using a bar coater so that the thickness after drying was 1.0 μm. Thereafter, by drying the film in an oven set at 140° C. for 5 minutes, a laminate (laminate for an infrared ablation layer) in which an infrared ablation layer was formed on the cover film was produced.

[0189] [Production of Flexographic Printing Plate Precursor]

[0190] An adhesive was applied to one side of a PET film (substrate) having a thickness of 125 μm to form an adhesive layer on the substrate. The photosensitive resin composition prepared as described above was sandwiched between the above-described adhesive layer and the infrared ablation layer of the laminate for an infrared ablation layer produced as described above, and the laminate was pressed with a press machine heated to 80° C. so that the thickness of the layer (photosensitive layer) of the photosensitive resin composition was 1.14 mm, thereby producing a flexographic printing plate precursor including the substrate, the adhesive layer, the photosensitive layer, the infrared ablation layer, and the protective film in this order.

Examples 2 to 7 and Comparative Examples 1 and 2

[0191] A flexographic printing plate precursor was produced in the same manner as in Example 1, except that composition of the photosensitive resin composition was changed to the composition shown in Table 2.

[0192] [Evaluation]

[0193] With regard to the produced flexographic printing plate precursor, the following evaluations were performed.

[0194] <Water Developability>

[0195] The cover film of the produced flexographic printing plate precursor was peeled off, and the produced flexographic printing plate precursor was exposed with an exposure device in which 15 40 W chemical lamps were arranged for 2 seconds from the substrate side from a distance of 15 cm (back exposure). Thereafter, development was performed for 3 minutes in a brush-type washing machine (liquid temperature: 50° C.) containing an aqueous developer in which the concentration of detergent (additive-free dishwashing soap, manufactured by MIYOSHI SOAP CORPORATION) was adjusted to 0.5%. Thereafter, the obtained flexographic printing plate was dried with hot air of 60° C. until the moisture was removed.

[0196] The thickness of the obtained flexographic printing plate was measured using a constant pressure thickness measuring device, and the change in film thickness per minute (development speed) was calculated from the change in thickness before and after development. The evaluation was performed according to the following standards. The results are shown in Table 2 below. Practically, it is preferable that the evaluation is B or higher.

[0197] (Evaluation Standard)

[0198] A: development speed was 170 μm/min or more.

[0199] B: development speed was 100 μm/min or more and less than 170 μm/min.

[0200] C: development speed was less than 100 μm/min.

[0201] <Printing Durability>

[0202] The cover film of the produced flexographic printing plate precursor was peeled off, and the produced flexographic printing plate precursor was exposed with an exposure device in which 15 40 W chemical lamps were arranged for 15 seconds from the substrate side from a distance of 15 cm (back exposure). Thereafter, a negative pattern was formed on the infrared ablation layer using CDI Spark 2120 manufactured by ESKO. Thereafter, the produced flexographic printing plate precursor was exposed with the above-described exposure device for 8 minutes from the infrared ablation layer side from a distance of 15 cm (main exposure). Thereafter, development was performed for 10 minutes in a brush-type washing machine (liquid temperature: 50° C.) containing an aqueous developer in which the concentration of detergent (additive-free dishwashing soap, manufactured by MIYOSHI SOAP CORPORATION) was adjusted to 0.5%. Thereafter, the obtained flexographic printing plate was dried with hot air of 60° C. until the moisture was removed. Thereafter, the produced flexographic printing plate precursor was exposed with the above-described exposure device for 8 minutes from the photosensitive layer side from a distance of 15 cm (post exposure).

[0203] In this way, a flexographic printing plate was produced.

[0204] The image area of the produced flexographic printing plate was rubbed 4 times using a continuous load-type scratch resistance strength tester (HEIDON TYPE: 18) and using a cotton waste cloth as a rubbing member under conditions of a load of 500 g and a reciprocating speed of 100 mm/min. For 10 independent dots with a diameter of 500 μm, which had been specified before the rubbing test, whether or not the independent dots were chipped or broken after the rubbing test was evaluated according to the following standard.

[0205] The results are shown in Table 2 below. Practically, it is preferable that the evaluation is B or higher.

[0206] (Evaluation Standard)

[0207] A: none of the 10 independent dots were chipped or broken.

[0208] B: 1 or 2 of the 10 independent dots were chipped or broken.

[0209] C: 3 or more of the 10 independent dots were chipped or broken.

[0210] <Solvent Resistance>

[0211] The flexographic printing plate produced for the evaluation of printing durability was immersed in a solution containing 1-propanol (85% by mass) and ethyl acetate (15% by mass) at 25° C. for 24 hours, and the mass increase ratio (weight swelling ratio) was measured. The results are shown in Table 2 below. Practically, it is preferable that the evaluation is B or higher.

[0212] (Evaluation Standard)

[0213] A: mass increase ratio was less than 10%.

[0214] B: mass increase ratio was 10% or more and less than 20%.

[0215] C: mass increase ratio was 20% or more.

TABLE-US-00002 TABLE 2 Composition of photosensitive layer (photosensitive resin composition) Polymerization Synthetic latex Monomer Base rubber initiator Performance evaluation Part by Part by Part by Part by Water Printing Solvent Type mass Type mass Type mass Type mass developability durability resistance Example 1 Synthetic latex 1 55 NK ESTER 15 NF35R 25 Irgacure 651 4.8 B B A NOD-N Example 2 Synthetic latex 2 55 NK ESTER 15 NF35R 25 Irgacure 651 4.8 B B A NOD-N Example 3 Synthetic latex 3 55 NK ESTER 15 NF35R 25 Irgacure 651 4.8 A B A NOD-N Example 4 Synthetic latex 4 55 NK ESTER 15 NF35R 25 Irgacure 651 4.8 A B A NOD-N Example 5 Synthetic latex 5 55 NK ESTER 15 NF35R 25 Irgacure 651 4.8 A B A NOD-N Example 6 Synthetic latex 6 55 NK ESTER 15 NF35R 25 Irgacure 651 4.8 A B B NOD-N Example 7 Synthetic latex 4 45 NK ESTER 15 NF35R 35 Irgacure 651 4.8 B A A NOD-N Comparative Nipol LX111NF 55 NK ESTER 15 NF35R 25 Irgacure 651 4.8 C B A example 1 NOD-N Comparative Nipol LX111NF 65 NK ESTER 15 NF35R 15 Irgacure 651 4.8 B C A example 2 NOD-N

[0216] As shown in Tables 1 and 2, in a case where the water-dispersed latex (manufactured by Zeon Corporation, Nipol LX111NF) which contained water-dispersible particles having a surface C═C amount larger than 21, it was found that the water developability was inferior (Comparative Example 1).

[0217] In addition, in a case where the blending amount of the water-dispersed latex (manufactured by Zeon Corporation, Nipol LX111NF) was increased, it was found that, although the water developability was improved, the printing durability in a case of being made into a flexographic printing plate was inferior (Comparative Example 2).

[0218] On the other hand, in a case where the synthetic latex which contained water-dispersible particles having a surface C═C amount of 21 or less is used, it was found that the water developability was excellent and the printing durability in a case of being made into a flexographic printing plate was also good (Examples 1 to 7).

[0219] In addition, from the comparison between Examples 1 to 5 and Example 6, in a case where the glass transition temperature of the polymer constituting the water-dispersible particles in a single film was −52° C. or lower, it was found that the solvent resistance in a case of being made into a flexographic printing plate was good.