JP5160469B2 - Photosensitive resin composition for letterpress printing - Google Patents

Description

  The present invention relates to a photosensitive resin composition for letterpress printing, which is a plate material used for flexographic printing characterized by a cover film excellent in peelability from a protective layer, and a part of the photosensitive resin composition for letterpress printing. And a cover film that is peeled off during plate making.

  The photosensitive resin composition for letterpress printing in the present invention (hereinafter also referred to as photosensitive resin composition) is generally a structure in which a base film, a photosensitive resin composition layer, a protective layer, and a cover film are laminated in this order. It is what has. A relief is formed by peeling the cover film of such a photosensitive resin structure and exposing the photosensitive resin composition layer through a negative film. As a method for obtaining a relief (hereinafter referred to as plate making), a negative film is brought into close contact with the protective layer on the surface of the photosensitive resin composition layer, exposed to active light and selectively exposed with the negative film, and then the protective layer. In general, a method of forming a relief by removing an unexposed portion of the photosensitive resin composition layer with a developer.

  The protective layer is a thin layer that can be removed with a developer and covers the surface of the photosensitive resin composition layer. This is due to the following reason. Generally, since the surface of the photosensitive resin composition layer is often sticky, if the protective layer is not provided, the negative film is directly adhered to the photosensitive resin composition layer and peeled off. At that time, a peeling failure occurs due to adhesion, and both the plate and the negative film are damaged. If the protective layer is not provided, air bubbles enter during close contact with the negative film, uniform contact cannot be achieved, and image reproducibility also deteriorates.

  Usually, a base film coated with a photosensitive resin composition layer and a cover film coated with a protective layer are prepared and bonded so that the photosensitive resin composition layer and the protective layer are next to each other. And applying heat to produce a photosensitive resin structure for letterpress printing. At the time of plate making, the cover film of the photosensitive resin structure is peeled off and exposed to light through a negative film.

  As the cover film, a PET film is generally used in many cases, but the peelability from the protective layer is poor, and the cover film is peeled off while a part of the protective layer is adhered, resulting in a photosensitive resin. There is a problem that a portion having no protective layer appears on the surface of the composition, which is not preferable.

  As a method for improving the peelability of the cover film, a method of laminating a silicone resin by coating on the film (Patent Literatures 1 and 2) and a method of laminating a fluorine-containing resin (Patent Literature 3) are generally used. However, a film coated with a fluorine-containing resin or a silicone resin has a problem that the peeling force is too high, and the adhesiveness is poor in the process of forming the photosensitive resin structure, and the film is peeled off during the process. Further, the method of laminating the silicone resin has a problem that the silicone adheres to the protective layer and consequently contaminates the negative. In addition, since fluorine compounds are difficult to adopt due to environmental problems, there was no cover film that has both moderate peelability and moderate adhesion, no negative film contamination, and excellent environmental aspects.

JP-A-7-196984 JP 2005-125656 A JP 2004-114620 A

  An object of this invention is to provide the cover film which exhibits moderate peelability and moderate adhesiveness with respect to a protective layer.

  Another object of the present invention is to provide a photosensitive resin composition for letterpress printing that combines moderate peelability and moderate adhesion between a cover film and a protective layer, and has a low environmental impact during disposal. To do.

The present invention constitutes a part of a photosensitive resin structural body for letterpress printing, and is a cover film that is peeled off during plate making,
It has a resin layer on the surface, the resin layer contains an acid-modified polyolefin resin having an acid-modified component of 1 to 10% by mass, a crosslinking agent and / or polyvinyl alcohol, and the crosslinking agent is a carbodiimide compound and / or an oxazoline compound. Composed of
When the content of the crosslinking agent with respect to 100 parts by weight of the acid-modified polyolefin resin is X (parts by mass) and the content of polyvinyl alcohol is Y (parts by mass), the contents X and Y are expressed by the following relational expression (1) or ( A cover film characterized by satisfying at least one of 2);
(1) 1 ≦ X ≦ 50 and 0 ≦ Y ≦ 1000;
(2) 0 ≦ X ≦ 50 and 5 ≦ Y ≦ 1000.

  The present invention also has a structure in which a base film, a photosensitive resin composition layer, a protective layer, and the cover film are laminated in this order, and the cover film is laminated so that the resin layer is adjacent to the protective layer. The present invention relates to a photosensitive resin composition for letterpress printing.

The cover film of the present invention exhibits moderate peelability and moderate adhesion to the protective layer.
The photosensitive resin constituent for letterpress printing of the present invention has appropriate releasability and appropriate adhesion between the cover film and the protective layer. Therefore, at the time of manufacture, the cover film is not peeled off from the protective layer. Also, at the time of plate making, the cover film can be peeled off without part of the protective film adhering to the protective layer or part of the protective layer adhering to the cover film in the peeling step, so there is a trouble during exposure. Absent. In addition, a release agent such as a silicone compound, a fluorine compound, waxes, and a surfactant is not required for causing the cover film to exhibit a desired peelability. For this reason, there is no contamination of the negative film due to adhesion of the release agent to the protective layer. In addition, since it is not necessary to use a release agent containing a halogen element such as fluorine, the burden on the environment at the time of disposal is small.

It is a cross-sectional schematic diagram which shows the structure of the photosensitive resin structure which concerns on this invention. (A)-(C) are the cross-sectional schematic diagrams for demonstrating the platemaking method using the photosensitive resin structure which concerns on this invention.

[Photosensitive resin composition]
The photosensitive resin composition for letterpress printing according to the present invention (hereinafter also referred to as photosensitive resin composition) has a structure in which a base film, a photosensitive resin composition layer, a protective layer, and a cover film are laminated in this order. ing. An example of a schematic cross-sectional view showing such a structure is shown in FIG. In FIG. 1, 1 is a base film, 2 is a photosensitive resin composition layer, 3 is a protective layer, and 4 is a cover film.

(Cover film)
The cover film 4 constitutes a part of the photosensitive resin structure and is peeled off during plate making. The cover film has a predetermined resin layer on the surface, and is laminated so that the resin layer is adjacent to the protective layer in the photosensitive resin structure.

  The cover film 4 is usually provided with a resin layer 42 on the support film 41 and may have an adhesive layer (not shown) between the support film 41 and the resin layer 42. Hereinafter, the support film constituting the cover film is expressed as a support film (A), and the predetermined resin layer 42 formed on the cover film surface is expressed as a resin layer (B).

  Examples of the resin material that can be used for the support film (A) 41 include polyester resins, polyolefin resins such as polyethylene and polypropylene, polystyrene resins, 6-nylon, poly-m-xylylene adipamide (MXD6 nylon), and the like. Polyamide resins, polycarbonate resins, polyacrylonitrile resins, polyimide resins, and multilayers of these resins (for example, nylon 6 / MXD / nylon 6, nylon 6 / ethylene-vinyl alcohol copolymer / nylon 6) and mixtures Etc. The support film may be stretched. The support film may contain known additives and stabilizers such as antistatic agents, plasticizers, lubricants, antioxidants and the like. The support film may have a surface subjected to corona treatment, plasma treatment, ozone treatment, chemical treatment, solvent treatment or the like as a pretreatment in order to improve adhesion when laminated with the resin layer (B). Especially, the polyester film excellent in dimensional stability, heat resistance, mechanical performance, and excellent adhesiveness with a resin layer (B) is preferable. Specific examples of the polyester film include films made of polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, polylactic acid, and copolymers thereof. Among these, polyethylene terephthalate is particularly preferable from the viewpoint of cost and performance. Considering dimensional stability, a film stretched in at least one direction is preferable, and a biaxially stretched film is more preferable.

  The thickness of the support film (A) is usually 75 to 250 μm, more preferably 100 to 200 μm, and most preferably 100 to 150 μm. The thickness of the support film (A) is preferably a value such that a value obtained by subtracting the thickness (μm) of the support film (A) from the thickness (μm) of the base film 1 is 0 to 100 μm. If the difference in thickness exceeds 100 μm, the structure is deflected in the process of producing the photosensitive resin structure, which is not preferable. On the other hand, if the thickness of the base film is thinner than the thickness of the support film (A), it is difficult to peel off.

  The surface on the resin layer (B) forming side of the support film (A) preferably has a center plane average roughness (Sa) of 0.01 to 0.3, more preferably 0, from the viewpoint of improving resolution. .01 to 0.1. If Sa is less than 0.01, the cover film and the protective layer may be in close contact with each other and the peelability may be inferior, which is not preferable. When Sa exceeds 0.3, the surface roughness of the support film is transferred to the protective layer to be laminated, and light is scattered by the protrusions of the protective layer in the photosensitive process after the support film is peeled off. This is not preferable because the resolution of image reproduction obtained as described above decreases.

The resin layer (B) 42 contains at least an acid-modified polyolefin resin and a crosslinking agent and / or polyvinyl alcohol.
The acid-modified polyolefin resin contained in the resin layer (B) needs to have an acid-modified component content of 1 to 10% by mass of the acid-modified polyolefin resin, preferably 1 to 7% by mass, and 2 to 5%. The mass% is more preferable, and 2-3 mass% is particularly preferable. When there is too little quantity of an acid modification component, sufficient adhesiveness with a support film (A) may not be acquired, and there exists a possibility of contaminating a protective layer. Furthermore, it tends to be difficult to disperse the acid-modified polyolefin resin in water. On the other hand, when there is too much quantity of an acid modification component, there exists a tendency for peelability with a protective layer to fall.

  Examples of the acid-modifying component include an unsaturated carboxylic acid component. Examples of unsaturated carboxylic acid components include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, and the like, as well as unsaturated dicarboxylic acid half esters and half amides. It is done. Among these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferable from the viewpoint of dispersion stability of the resin, and acrylic acid, methacrylic acid, and maleic anhydride are particularly preferable.

  The olefin component which is the main component of the acid-modified polyolefin resin is not particularly limited, and examples thereof include alkene having 2 to 6 carbon atoms such as ethylene, propylene, isobutylene, 2-butene, 1-butene, 1-pentene and 1-hexene. Is preferred. A mixture thereof may be used. Among these, alkene having 2 to 4 carbon atoms such as ethylene, propylene, isobutylene and 1-butene is more preferable, ethylene and propylene are further preferable, and ethylene is most preferable.

  The acid-modified polyolefin resin preferably contains a (meth) acrylic acid ester component for the purpose of improving the adhesion to the support film (A), particularly the polyester film. When the (meth) acrylic acid ester component is included, the content is preferably 0.5 to 40% by mass of the acid-modified polyolefin resin, and in order to have good adhesion to the polyester film, this range is The content is more preferably 1 to 20% by mass, and further preferably 3 to 10% by mass. Examples of the (meth) acrylic acid ester component include an esterified product of (meth) acrylic acid and an alcohol having 1 to 30 carbon atoms, and (meth) acrylic acid and carbon number 1 from the viewpoint of easy availability. Esterified products with ˜20 alcohols are preferred. Specific examples of such compounds include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, (meth) acrylic acid. Examples include octyl, decyl (meth) acrylate, lauryl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, and the like. Mixtures of these may be used. Among these, from the viewpoint of adhesiveness with a polyester film), methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, hexyl acrylate, octyl acrylate are more preferable, and ethyl acrylate Further, butyl acrylate is more preferable, and ethyl acrylate is particularly preferable. “(Meth) acrylic acid” means “acrylic acid or methacrylic acid”.

  Each component constituting the acid-modified polyolefin may be copolymerized in the acid-modified polyolefin resin, and its form is not limited. Examples of the state of copolymerization include random copolymerization, block copolymerization, and graft copolymerization (graft modification).

The composition of the acid-modified polyolefin resin and the content of each component can be controlled by adjusting the amount charged at the time of synthesis of the acid-modified polyolefin resin, and the acid-modified polyolefin resin is subjected to ¹ H-NMR analysis to be unique to each component. This can be found by observing the peak.
Content of each component is the ratio of the said component with respect to all the components which comprise acid-modified polyolefin resin.

  The melting point of the acid-modified polyolefin resin is preferably 60 to 150 ° C, particularly preferably 80 to 150 ° C, more preferably 85 to 130 ° C, and further preferably 90 to 115 ° C. When the temperature exceeds 150 ° C., a treatment at a high temperature is required for forming the resin layer.

  The Vicat softening point of the acid-modified polyolefin resin is preferably 30 to 130 ° C, particularly preferably 50 to 130 ° C, more preferably 53 to 110 ° C, and more preferably 55 to 90 ° C. When the Vicat softening point is less than 30 ° C., the peelability is lowered, and when it exceeds 130 ° C., a treatment at a high temperature is required for forming the resin layer.

  The melt flow rate of the acid-modified polyolefin resin is preferably 1 to 1000 g / 10 minutes at 190 ° C. and 2160 g load, more preferably 1 to 500 g / 10 minutes, and 2 to 300 g / 10 minutes. Is more preferable, and 2 to 200 g / 10 min is particularly preferable. When the amount is less than 1 g / 10 minutes, it is difficult to produce a resin and it is difficult to obtain an aqueous dispersion. If it exceeds 1000 g / 10 min, the adhesiveness of the resin layer (B) to the polyester film is lowered, and the resin layer tends to migrate to the protective layer.

  Examples of the trade name of the acid-modified polyolefin resin that can be used in the present invention include Bondine series, which is a maleic anhydride polyolefin resin manufactured by Arkema. Specific product names include “LX-4110”, “HX-8210”, “HX-8290”, “AX-8390”, and the like.

  The resin layer (B) contains a crosslinking agent and / or polyvinyl alcohol. The crosslinking agent is a carbodiimide compound and / or an oxazoline compound. That is, the resin layer (B) contains one or more compounds selected from the group consisting of carbodiimide compounds, oxazoline compounds, and polyvinyl alcohol. It is not clear how these compounds work on the resin layer (B), and as a result, excellent peelability and adhesion, but combining an acid-modified polyolefin resin with a crosslinking agent and / or polyvinyl alcohol Thus, the easy adhesion at high temperature produced by the resin layer (B) is moderately reduced, and the stable peelability with little temperature dependence is exhibited. Can be expressed. Further, it is possible to cope with a case where the level of peelability is changed depending on the kind of the protective layer and the application. When the carbodiimide compound, the oxazoline compound and the polyvinyl alcohol are not contained, even if other crosslinking agent is contained, good peelability without temperature dependency cannot be obtained.

  The resin layer (B) only needs to contain at least one of a crosslinking agent or polyvinyl alcohol. When one of the crosslinking agent or the polyvinyl alcohol is contained, if the content is too large, the peelability to the protective layer is lowered, the stability of the coating liquid of the resin layer (B) is deteriorated, and the coating spots are As a result, the adhesion with the protective layer is partially deteriorated. If the content is too small, the temperature dependency of the releasability with respect to the protective layer becomes high, and it is not preferable because it changes with time or becomes difficult to peel off due to high-temperature treatment. When both the crosslinking agent and the polyvinyl alcohol are contained, if one or both contents are too large, the peelability to the protective layer is lowered, or the stability of the coating liquid of the resin layer (B) is deteriorated, Coat spots occur, and as a result, the adhesion with the protective layer is partially deteriorated. When both are contained, if the content of both does not reach the respective effective amount, the temperature dependency of the peelability to the protective layer becomes high, and changes with time, or the high temperature treatment makes it difficult to peel. It is not preferable.

In this invention, content of a crosslinking agent and polyvinyl alcohol is determined from such a viewpoint. Specifically, when the content of the crosslinking agent with respect to 100 parts by weight of the acid-modified polyolefin resin is X (parts by mass) and the content of polyvinyl alcohol is Y (parts by mass), the contents X and Y are expressed by the following relational expression (1 ) Or (2) is satisfied.
(1) 1 ≦ X ≦ 50 and 0 ≦ Y ≦ 1000.
(2) 0 ≦ X ≦ 50 and 5 ≦ Y ≦ 1000.

From the viewpoint of the balance between the peelability and adhesion of the resin layer (B) to the protective layer, both of the above relational expressions (1) and (2) are preferably satisfied. That is, the contents X and Y preferably satisfy the following relational expression (3).
(3) 1 ≦ X ≦ 50 and 5 ≦ Y ≦ 1000.

  In such a preferred embodiment, the content X of the crosslinking agent and the content Y of the polyvinyl alcohol are more preferably within the ranges shown below.

  The content X of the cross-linking agent is more preferably 3 to 30 parts by mass and further preferably 5 to 10 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin, from the viewpoint of further improving the peelability with respect to the protective layer. The carbodiimide compound and the oxazoline compound can be used in combination, and in that case, the total amount of these may be the content X of the crosslinking agent and satisfy the above range.

  The content Y of the polyvinyl alcohol is 5 to 1000 parts by weight, particularly 10 with respect to 100 parts by weight of the acid-modified polyolefin resin, from the viewpoint of improving the stability of the coating liquid of the resin layer (B) and improving the peelability at high temperature. -600 mass parts is more preferable, 20-400 mass parts is further more preferable, and 30-200 mass parts is the most preferable.

  As the crosslinking agent, at least one of a carbodiimide compound and an oxazoline compound is used, and an oxazoline compound is more preferable in terms of mixing stability and storage stability. By crosslinking the acid-modified polyolefin resin in the resin layer (B), the crosslinking agent moderately reduces the adhesiveness at high temperatures exhibited by the functional groups in the acid-modified polyolefin resin, and exhibits releasability.

  The carbodiimide compound is not particularly limited as long as it has one or more carbodiimide groups in the molecule. The carbodiimide compound forms an ester with two carboxyl groups in the acid-modified part of the acid-modified polyolefin resin in one carbodiimide part to achieve crosslinking. Specific examples of the carbodiimide compound include, for example, p-phenylene-bis (2,6-xylylcarbodiimide), tetramethylene-bis (t-butylcarbodiimide), cyclohexane-1,4-bis (methylene-t-butylcarbodiimide). Examples thereof include compounds having a carbodiimide group such as polycarbodiimide which is a polymer having a carbodiimide group. These 1 type (s) or 2 or more types can be used. Among these, polycarbodiimide is preferable from the viewpoint of ease of handling.

  As a commercially available product of polycarbodiimide, there is a carbodilite series manufactured by Nisshinbo. More specifically, water-soluble type “SV-02”, “V-02”, “V-02-L2”, “V-04”; emulsion type “E-” 01 ”,“ E-02 ”; organic solution type“ V-01 ”,“ V-03 ”,“ V-07 ”,“ V-09 ”; solventless type“ V-05 ”.

  The oxazoline compound is not particularly limited as long as it has two or more oxazoline groups in the molecule. The oxazoline compound forms an amide ester with one carboxyl group in the acid-modified polyolefin resin in each of the two oxazoline moieties to achieve crosslinking). Specific examples of the oxazoline compound include, for example, 2,2′-bis (2-oxazoline), 2,2′-ethylene-bis (4,4′-dimethyl-2-oxazoline), 2,2′-p-phenylene. Examples thereof include compounds having an oxazoline group such as bis (2-oxazoline) and bis (2-oxazolinylcyclohexane) sulfide, and oxazoline group-containing polymers. These 1 type (s) or 2 or more types can be used. Among these, an oxazoline group-containing polymer is preferable because of ease of handling.

  An example of a commercially available oxazoline group-containing polymer is EPOCROSS series manufactured by Nippon Shokubai Co., Ltd. More specifically, it will be described using trade names. Water-soluble type “WS-500”, “WS-700”; emulsion type “K-1010E”, “K-1020E”, “K-1030E” , “K-2010E”, “K-2020E”, “K-2030E”, and the like.

  Polyvinyl alcohol is not particularly limited, and examples thereof include a completely or partially saponified vinyl ester polymer. Polyvinyl alcohol is dispersed in the acid-modified polyolefin resin in the resin layer (B), so that the easy adhesion at high temperatures produced by the resin layer (B) is moderately reduced, and stable peeling with low temperature dependence is achieved. And can exhibit stable releasability over time. As described later, the polyvinyl alcohol in the present invention preferably has water solubility for use as a liquid.

  The average degree of polymerization of polyvinyl alcohol is not particularly limited, and may be, for example, 300 to 5,000. From the viewpoint of improving the stability of the coating liquid of the resin layer (B), 300 to 2,000 is preferable. preferable.

  As a commercially available polyvinyl alcohol, when it demonstrates using a brand name, the specific brand name "JC-05", "VC-10", "ASC-05X" of "J-poval" of Nippon Vinegar Poval Co., Ltd. ”,“ UMR-10HH ”; specific product names“ PVA-103 ”and“ PVA-105 ”of“ Kuraray Poval ”manufactured by Kuraray Co., Ltd. Specific product names of “Denka Poval” manufactured by Denki Kagaku Kogyo Co., Ltd., “PC-1000”, “PC-2000” and the like.

  In the resin layer (B), the total content of the silicone compound, the fluorine compound, the wax, and the surfactant is preferably 1 part by mass or less with respect to 100 parts by mass of the acid-modified polyolefin resin. The smaller the amount, the better the adhesion between the resin layer (B) and the support film (A), and the contamination of the protective layer is suppressed. The content is more preferably 0.5 parts by mass or less, still more preferably 0.1 parts by mass or less, and most preferably not.

  Silicone compounds can be used in emulsions of organopolysiloxanes having amino functional groups and / or epoxy groups, organopolysiloxane emulsions having amino functional groups and epoxy groups, silanes having epoxy groups or amino groups, and optionally further hydroxyl groups. Or what added the emulsion of the organopolysiloxane which has a hydrolysable group etc. is illustrated.

  Examples of the fluorine compound include fluorine-containing polymethacrylate, fluorine-containing polyacrylate, and fluorine-based block copolymer.

  The wax means a plant wax, animal wax, mineral wax, petrochemical wax or the like having a number average molecular weight of 10,000 or less. Specifically, candelilla wax, carnauba wax, rice wax, wood wax, berry wax, jojoba wax, shea butter, beeswax, shellac wax, lanolin wax, whale wax, montan wax, ceresin, paraffin wax, microcrystalline wax, synthetic Examples thereof include polyethylene wax, synthetic polypropylene wax, and synthetic ethylene-vinyl acetate copolymer wax.

Examples of the surfactant include a cationic surfactant, an anionic surfactant, a nonionic (nonionic) surfactant, an amphoteric surfactant, a fluorosurfactant, and a reactive surfactant. In addition to those generally used for emulsion polymerization, emulsifiers are also included.
Examples of the cationic surfactant include alkyl trimethyl ammonium salt, dialkyl dimethyl ammonium salt, alkyl benzyl dimethyl ammonium salt and the like.
Anionic surfactants include higher alcohol sulfates, higher alkyl sulfonic acids and salts thereof, alkylbenzene sulfonic acids and salts thereof, polyoxyethylene alkyl sulfate salts, polyoxyethylene alkyl phenyl ether sulfate salts, vinyl sulfosuccinates. Etc.
Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyethylene glycol fatty acid ester, ethylene oxide propylene oxide block copolymer, polyoxyethylene fatty acid amide, ethylene oxide-propylene oxide copolymer, etc. And a sorbitan derivative such as a polyoxyethylene sorbitan fatty acid ester.
Examples of amphoteric surfactants include lauryl betaine and lauryl dimethylamine oxide.
Examples of reactive surfactants include alkylpropenylphenol polyethylene oxide adducts and their sulfate esters, allyl alkylphenol polyethylene oxide adducts and their sulfate esters, allyl dialkylphenol polyethylene oxide adducts and their sulfate esters, etc. And compounds having a reactive double bond.

  The thickness of the resin layer (B) is preferably in the range of 0.01 to 5 μm, more preferably 0.1 to 2 μm, from the viewpoint of further improving the peelability and adhesion to the protective layer. More preferably, it is 2 to 1 μm, and particularly preferably 0.3 to 0.7 μm.

The wetting tension on the surface of the resin layer (B) is preferably 30 to 50 mN / m, and more preferably 32 to 40 mN / m. When the wetting tension is less than 30 mN / m, it may be difficult to laminate a protective layer on the resin layer (B). The wetting tension means a critical surface tension by Zisman. This can be measured by the method described in JIS K6768.
The wetting tension can be controlled by adjusting the amount of the acid-modified component of the resin layer (B) and the amount of polyvinyl alcohol.

  From the viewpoint of peelability and adhesion to the protective layer of the resin layer (B), an adhesive material using an acrylic adhesive on the resin layer (B) surface of the cover film was measured by thermocompression bonding at 70 ° C. for 20 hours. It is preferable that the peeling strength between the resin layer (B) and the pressure-sensitive adhesive is 0.5 to 4.3 N / cm. The peel strength is more preferably 1.0 to 4.0 N / cm, and particularly 1.3 to 3.0 N / cm. If the peel strength exceeds 4.3 N / cm, the peelability from the protective layer is poor, and the cover film is peeled off with a part of the protective layer adhered to the surface of the photosensitive resin composition. This is not preferable because a portion without a protective layer appears. On the other hand, if the peel strength is less than 0.5 N / cm, the adhesion is poor in the step of creating the photosensitive resin structure, and it is not preferable because it peels off in the middle of the step.

  The cover film is manufactured by coating a liquid material containing at least an acid-modified polyolefin resin and a crosslinking agent and / or polyvinyl alcohol on the support film (A) and then drying to form a resin layer (B). Depending on the method, it can be easily obtained industrially.

The method for producing the liquid material is not particularly limited as long as each component is uniformly mixed in the liquid medium. For example, the following method is mentioned.
(I) A method of adding and mixing a dispersion or solution of a crosslinking agent and / or polyvinyl alcohol to a dispersion or solution of an acid-modified polyolefin resin.
(Ii) A method of liquefying a mixture of an acid-modified polyolefin resin and polyvinyl alcohol.

  In the case of the above method (i), a dispersion or solution of each component may be appropriately mixed. When a dispersion or solution of polyvinyl alcohol is used, the solute concentration is not particularly limited. However, 5-10 mass% is preferable from the point of handleability.

  In the case of the above method (ii), polyvinyl alcohol may be added when the acid-modified polyolefin resin is liquefied.

  Even when other components are added, the addition can be performed at any stage in the production method (i) or (ii).

  The solvent in the liquid material is not particularly limited as long as the liquid material can be applied onto the substrate. Specifically, water, an organic solvent, or an aqueous medium containing water and an amphiphilic organic solvent can be used. Among them, it is preferable to use water or an aqueous medium in view of the environment. When the liquid material contains polyvinyl alcohol, it is preferable to use water or an aqueous medium as the medium because of the solubility of polyvinyl alcohol.

  Examples of organic solvents include diethyl ketone (3-pentanone), methyl propyl ketone (2-pentanone), methyl isobutyl ketone (4-methyl-2-pentanone), 2-hexanone, 5-methyl-2-hexanone, and 2-to. Ketones such as butanone, 3-heptanone, 4-heptanone, cyclopentanone, cyclohexanone; aromatic hydrocarbons such as toluene, xylene, benzene, Solvesso 100, Solvesso 150; butane, pentane, hexane, cyclohexane, heptane Aliphatic hydrocarbons such as octane, nonane; methylene chloride, chloroform, carbon tetrachloride, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, Halogen-containing compounds such as p-dichlorobenzene; acetic acid Esters such as chill, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, 3-methoxybutyl acetate, methyl propionate, ethyl propionate, diethyl carbonate, γ-butyrolactone, isophorone; Amphiphilic organic solvents and the like can be mentioned.

  The aqueous medium means a solvent containing water and an amphiphilic organic solvent and having a water content of 2% by mass or more. The amphiphilic organic solvent is an organic solvent having a water solubility of 5% by mass or more at 20 ° C. [For the solubility of water in an organic solvent at 20 ° C., for example, “Solvent Handbook” (Kodansha) Scientific, 1990, 10th edition)]. Specifically, alcohols such as methanol, ethanol (hereinafter abbreviated as “EA”), n-propanol (hereinafter abbreviated as “NPA”), isopropanol (hereinafter abbreviated as “IPA”); Ethers such as 4-dioxane; Ketones such as acetone and methyl ethyl ketone; Esters such as methyl acetate, n-propyl acetate, isopropyl acetate, methyl propionate, ethyl propionate, and dimethyl carbonate; In addition, diethylamine containing ammonia Organic amines such as triethylamine (hereinafter abbreviated as “TEA”), diethanolamine, triethanolamine, N, N-dimethylethanolamine (hereinafter abbreviated as “DMEA”), N, N-diethylethanolamine, N-diethanolamine, etc. Compound; 2-pyro Don, and the like lactams such as N- methyl-2-pyrrolidone.

The method for dispersing the acid-modified polyolefin resin in the aqueous medium as described above is not particularly limited, and examples thereof include those described in International Publication WO02 / 055598.
The dispersed particle size of the acid-modified polyolefin resin in the aqueous medium preferably has a number average particle size of 1 μm or less from the viewpoint of stability when mixed with other components and storage stability after mixing. More preferably, it is 8 μm or less. Such a particle size can be achieved by the production method described in WO02 / 055598.

  The solid content in the liquid can be appropriately selected depending on the lamination conditions, the target thickness and performance, and is not particularly limited. However, 1-60 mass% is preferable and 5-30 mass% is more preferable in order to maintain the viscosity of a liquid substance moderately and to form a favorable resin layer.

  As a method of coating a liquid material on a substrate, known methods such as gravure roll coating, reverse roll coating, wire bar coating, lip coating, air knife coating, curtain flow coating, spray coating, dip coating, brush coating method Etc.

A uniform resin layer is obtained by coating the liquid material uniformly on the surface of the support film (A) by these methods, setting it at around room temperature as necessary, and then subjecting it to a drying treatment or a heat treatment for drying. (B) can be formed in close contact with the film. In particular, when the resin layer (B) contains a crosslinking agent, it is preferable to perform heat treatment for drying in order to perform crosslinking simultaneously with drying.
The resin layer (B) is applied to the support film (A), and the dried film is once wound up in a roll shape. The film roll is preferably aged so that the peelability and adhesion of the resin layer (B) do not change with time.

  The heating time and heating temperature for drying, and the aging temperature and aging time affect the peelability and adhesion. If the drying temperature, drying time, aging temperature, and aging time are insufficient, the crosslinking reaction of the resin layer (B) becomes insufficient, and the peelability and adhesiveness change with time, which is not preferable.

The drying temperature is not particularly limited, and is preferably 80 ° C to 160 ° C, more preferably 100 to 140 ° C, and most preferably 110 to 130 ° C. When the drying temperature is less than 80 ° C., the crosslinking reaction of the resin layer (B) does not proceed sufficiently, so that the adhesiveness with the protective layer is increased and the protective layer adheres to the cover film. When the drying temperature exceeds 160 ° C., the support film that is the base material of the cover film contracts, which is not preferable.
The drying time is 5 seconds to 5 minutes, preferably 10 seconds to 1 minute. If the drying time is less than 5 seconds, the cross-linking reaction of the resin layer (B) does not proceed sufficiently, so that the adhesiveness with the protective layer is increased and the protective layer adheres to the cover film. In order to make the drying time exceed 5 minutes, it is necessary to extremely slow the processing speed, which is not economical.

  The aging temperature is 30 to 80 ° C., preferably 35 to 70 ° C., and the aging period is half to 7 days, preferably 1 to 3 days. When the aging temperature is less than 30 ° C, or when the aging period is less than half a day, the effect of aging is poor, and when it exceeds 80 ° C or exceeds 7 days, it is not economical.

(Protective layer)
The protective layer 3 is usually 0.5 to 20 μm thick and completely covers the relief forming surface of the photosensitive resin layer with a uniform thickness. The polymer for forming the protective layer is not particularly limited as long as it has necessary characteristics as a general protective layer for a flexographic photosensitive resin composition and can be dissolved and removed by a developer during plate making. . Examples of polymers forming such a protective layer include polyamides, alkyl celluloses, hydroxyalkyl celluloses, nitrocelluloses, cellulose esters, copolymers of monovinyl-substituted aromatic hydrocarbons and conjugated dienes, and monovinyl-substituted aromatic hydrocarbons. One or more polymers selected from the group consisting of hydrogenated reactants of conjugated diene copolymers and the like can be used.

  The protective layer can be obtained by dissolving or dispersing a polymer as a raw material for the protective layer in a solvent or the like, and applying and drying on the resin layer (B) surface of the cover film. At this time, for the purpose of ensuring the necessary properties of the protective layer, an ultraviolet absorber, a release agent, a plasticizer, an adhesion adjusting agent, and the like can be appropriately added.

(Base film)
The base film 1 is not particularly limited as long as it can be conventionally used as a base film in the field of photosensitive resin constituents, and examples thereof include polyester resins, polyolefin resins such as polyethylene and polypropylene, polystyrene resins, and 6-nylon. Polyamide resin such as poly-m-xylylene adipamide (MXD6 nylon), polycarbonate resin, polyacrylonitrile resin, polyimide resin, and multilayers of these resins (for example, nylon 6 / MXD / nylon 6, nylon 6) / Ethylene-vinyl alcohol copolymer / nylon 6) and mixtures. The base film may be stretched. The base film may contain known additives and stabilizers such as antistatic agents, plasticizers, lubricants, antioxidants and the like. Among them, a polyester film is preferable because of its dimensional stability. Examples of the polyester film include polyethylene terephthalate, polybutylene terephthalate, polynaphthalene terephthalate, polylactic acid, and copolymers thereof. Among these, polyethylene terephthalate is particularly preferable from the viewpoint of cost and performance. Considering dimensional stability, a film stretched in at least one direction is preferable, and a biaxially stretched film is more preferable. The thickness of the film is 75 to 500 μm, more preferably 100 to 250 μm, and most preferably 100 to 200 μm.

The base film may be a single polyester film, but an adhesive layer may be provided on the base film in order to firmly adhere to the photosensitive resin layer. Examples of the adhesive layer include a urethane adhesive, a urethane urea adhesive, a polyester adhesive, and an acrylic adhesive.
The thickness of the adhesive layer is usually 0.1 to 10 μm.

  The resin material constituting the base film may contain known additives and stabilizers such as antistatic agents, plasticizers, lubricants, antioxidants and the like. The base film may be subjected to corona treatment, plasma treatment, ozone treatment, chemical treatment, solvent treatment or the like as a pretreatment to improve adhesion when laminated with other materials. Silica, alumina or the like may be deposited on the base film, and other layers such as an antistatic layer and an ultraviolet absorbing layer may be laminated.

(Photosensitive resin composition layer)
The photosensitive resin composition layer 2 is such that a relief image obtained by selectively exposing the photosensitive resin composition layer has characteristics generally required as a flexographic printing plate, that is, a substrate to be printed. It is not particularly limited as long as it exhibits good printing performance with respect to the paper or film to be used, and the unexposed portion can be dissolved and removed by the developer. Examples of the binder polymer forming the photosensitive resin composition layer having such characteristics include styrene-butadiene-styrene block copolymers and monovinyl substituted aromatics represented by styrene-isoprene-styrene block copolymers. The thermoplastic elastomer which consists of a hydrocarbon and a conjugated diene is mentioned. These binder polymers usually occupy 40 to 90% by weight with respect to the entire photosensitive resin composition layer in order that the mechanical properties of the finally obtained flexographic printing plate become a practical level.

The photosensitive resin composition layer also contains a photosensitive material that can be polymerized with ultraviolet rays. As a photosensitive material, the photosensitive material conventionally used for manufacture of the photosensitive resin structure for letterpress printing can be used, for example, an ethylenically unsaturated compound is used. Specific examples of the ethylenically unsaturated compound include acrylate compounds, methacrylate compounds, maleimide derivatives, and fumaric acid esters. In particular, a compound containing one or more acrylate groups per 200 molecular weight of the compound and two or more acrylate groups in one molecule is more preferable. Specific examples of such compounds include hexanediol diacrylate, nonanediol diacrylate, and long-chain aliphatic diacrylate. Two or more kinds selected from these diacrylate compound groups can also be mixed and used. Other ethylenically unsaturated compounds can be used as necessary.
By containing these diacrylate compounds in the photosensitive resin composition layer, a relief image can be formed with a smaller dose in a process of curing the photosensitive resin composition layer with ultraviolet rays, thereby improving productivity. Is possible.
The content of the photosensitive material is usually 3 to 20% by weight with respect to the entire photosensitive resin composition layer.

  The photosensitive resin composition layer preferably contains a plasticizer elastomer from the viewpoint of developing good printability. Examples of the plasticizer elastomer include liquid rubber such as LPB manufactured by Nippon Petrochemical Co., Ltd., NISSO PB manufactured by Nippon Soda Co., Ltd., and Polyoil manufactured by Huls. The molecular weight of the plasticizer elastomer is preferably 500 to 5,000. As for content of a plasticizer elastomer, 5 to 40 weight% is preferable with respect to the whole photosensitive resin composition layer.

In the photosensitive resin composition layer, as a photopolymerization initiator, known radical polymerization initiators such as aromatic ketones and benzoin ethers, for example, benzophenone, Michler ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether , Α-methyl roll benzoin methyl ether, α-methoxybenzoin methyl ether, 2,2-ethoxyphenylacetophenone, 2,2-dimethoxy-2-phenylacetophenone, and the like can be contained. These compounds can be used alone or in combination of two or more.
Content of a photoinitiator is 0.1 to 20 weight% normally with respect to the whole photosensitive resin composition layer.

  Depending on the properties required for the photosensitive resin composition layer, a thermal polymerization inhibitor such as 2,6-di-t-butyl-p-cresol and an additive such as a colorant may be contained.

  The photosensitive resin composition layer can be formed by various methods. For example, the above-described blended components can be melt-kneaded with a kneader roll mill having a heating device or a screw extruder, and formed into a plate having a desired thickness with a T-type die, a press molding machine, or the like. Moreover, the compounding component mentioned above can also be melt | dissolved and mixed in solvents, such as chloroform, tetrachloroethylene, methyl ethyl ketone, toluene, for example, and it can cast in a mold and evaporate a solvent, and can also shape | mold into a plate shape. Furthermore, the photosensitive resin composition layer can also be obtained by dissolving or dispersing the above-described compounding components in a solvent or the like, and applying and drying on a base film.

  The thickness of the photosensitive resin composition layer in the photosensitive resin constituent is not particularly limited.

[Method for producing photosensitive resin composition]
In the photosensitive resin structure, a plate-shaped photosensitive resin composition layer is superposed on a base film, and a cover film coated with a protective layer is further formed thereon, and the surface coated with the protective layer is the photosensitive resin side. Thus, it can be manufactured by overlapping and press molding.

  The photosensitive resin composition can also be produced by a method similar to the above method except that the photosensitive resin composition layer is cast on the base film in a molten state.

  When the photosensitive resin composition layer is applied on the base film and dried to obtain the photosensitive resin composition, the cover film in which the protective layer is applied to the photosensitive resin composition layer application surface of the base film, It can be manufactured by overlaying and press molding so that the protective layer application surface is on the photosensitive resin side.

[Plate making method]
The photosensitive resin composition of the present invention is a solvent-based (non-aqueous) plate material that uses an organic solvent as a developer during plate making.
Hereinafter, a method for making a plate using the photosensitive resin composition of the present invention will be described.

  First, in the photosensitive resin structure, as shown in FIG. 2 (A), after peeling the cover film 4, as shown in FIG. 2 (B), the negative film 50 is adhered to the surface of the protective layer 3, It exposes and the exposed part 20 in the photosensitive resin composition layer 2 is hardened.

  As an ultraviolet light source for exposing and curing the photosensitive resin composition layer, for example, a high-pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, a xenon lamp, sunlight, or the like can be used. A desired relief layer can be obtained by exposing the photosensitive resin layer to ultraviolet rays through a negative film. In order to adjust the height of the relief image, the entire surface is irradiated with ultraviolet rays from the base film 1 side. . Either the relief forming exposure or the exposure from the base film 1 side may be performed first, or may be performed at the same time, but it is preferable to perform the exposure from the base film 1 side first from the viewpoint of image reproducibility. .

After the exposed portion 20 is sufficiently cured by exposure, the unexposed portion is dissolved and removed with a developer.
As the developing solution, an organic solvent is used. For example, a chlorine-based organic solvent such as tetrachloroethylene, hydrocarbons such as petroleum fraction, toluene and decalin, esters such as 3-methoxybutyl acetate and heptyl acetate, etc. What mixed alcohols, such as a propanol, a butanol, and a pentanol, in a solvent can be mentioned.

  A surfactant, an antifoaming agent, a dispersant, an emulsifier, a corrosion inhibitor, an anti-corruption agent, a pH adjuster, and the like may be added to the developer.

  The present invention will be specifically described below with reference to examples. However, the present invention is not limited by these.

(1) Composition of acid-modified polyolefin resin
^It calculated | required with the <1> H-NMR analyzer (The product made by Varian GEMINI2000 / 300, 300MHz). Orthodichlorobenzene (d ₄ ) was used as a solvent, and measurement was performed at 120 ° C.

(2) Melting point of acid-modified polyolefin resin 10 mg of resin is used as a sample, and measured using a DSC (Differential Scanning Calorimetry) apparatus (DSC7 manufactured by PerkinElmer Co., Ltd.) under a temperature rising rate of 10 ° C./min. The melting point was determined from the temperature rise curve.

(3) Vicat softening point of acid-modified polyolefin resin Measured by the method described in JIS K7206.

(4) Melt flow rate (MFR) of acid-modified polyolefin resin
It was measured by the method described in JIS K6730 (190 ° C., 2160 g load).

(5) Organic solvent content of aqueous dispersion Shimadzu Corporation gas chromatograph GC-8A [FID detector used, carrier gas: nitrogen, column packing material (manufactured by GL Sciences): PEG-HT (5%) − Uniport HP (60/80 mesh), column size: diameter 3 mm × 3 m, sample charging temperature (injection temperature): 150 ° C., column temperature: 60 ° C., internal standard substance: n-butanol], aqueous dispersion or aqueous A dispersion diluted with water was directly charged into the apparatus, and the content of the organic solvent was determined. The detection limit was 0.01% by mass.

(6) Solid content concentration of liquid material An appropriate amount of the liquid material was weighed and heated at 150 ° C. until the mass of the residue (solid content) reached a constant weight, thereby obtaining the solid content concentration.

(7) Number average particle diameter of acid-modified polyolefin resin particles The number average particle diameter was determined using a Microtrac particle size distribution analyzer UPA150 (MODEL No. 9340, dynamic light scattering method) manufactured by Nikkiso Co., Ltd. The refractive index of the resin used for particle diameter calculation was 1.57.

(8) Liquid Stability of Resin Layer (B) Coating Solution The storage stability of the dispersion when the polyester (A) was coated with the resin layer (B) dispersion was evaluated as follows. ○ is preferable, but use is possible even with Δ. × has operational problems.
X: gelation or thickening within 23 days at 23 ° C;
Δ: gelation or thickening within 2 weeks at 23 ° C;
○: No change for more than 2 weeks at 23 ° C.

(9) Thickness of resin layer The total thickness of a film (hereinafter referred to as “cover film”) in which the resin layer (B) is laminated on the support film (A) is measured with a contact-type film thickness meter, and supported from the measured value Obtained by reducing the thickness of the film (A).

(10) Center plane average roughness Sa (μm)
Using a Talysurf CCI6000 (non-contact type surface roughness measuring device) manufactured by Taylor Hobson, the sample fixed on the slide glass was actually measured with an objective lens 20 times, and a robust Gaussian filter 0.25 mm was used. The surface roughness was analyzed, and the arithmetic average of the deviation from the average value was defined as the center plane average roughness Sa (μm).

(11) Wetting tension of the cover film (resin layer (B) surface) A standard solution (ethylene glycol monoethyl ether / formamide) adjusted so that the surface tension changes in order according to the measurement method described in JIS K6768 This was indicated by the surface tension of the standard solution that was applied to the treated surface and determined to wet the resin layer surface.

(12) Peel strength of cover film A polyester adhesive tape (Nitto Denko Corporation, No. 31B / acrylic adhesive) having a width of 50 mm and a length of 150 mm is pressure-bonded to the resin layer (B) side of the obtained cover film with a rubber roll. And used as a sample. Sample is sandwiched in the form of metal plate / rubber plate / sample / rubber plate / metal plate, left at 2 kPa load and 70 ° C. atmosphere for 20 hours, then cooled to room temperature for 30 minutes or more, for peel strength measurement A sample was obtained. The peel strength between the adhesive tape and the release film of this peel strength measurement sample was measured with a tensile tester (manufactured by Intesco, precision universal material tester, type 2020) in a thermostatic chamber at 25 ° C. The peeling angle was 180 ° C. and the peeling speed was 300 mm / min. The peel strength (0.5 to 4.3) N / cm is a practically acceptable range, and (1.0 to 4.0) N / cm is a preferred range.

(13) Peelability between cover film and protective layer The peeled state when only the cover film was peeled off in the photosensitive resin structure was evaluated. ○ is desirable, but Δ can be used practically.
○: Only the cover film can be easily peeled off. At this time, there is no adhesion of the protective layer to the cover film, and no adhesion of the resin layer (B) to the protective layer.
Δ: Only the cover film can be peeled if attention is paid to the peeling speed and force. At this time, if peeling is performed while paying attention to the peeling speed and force, the cover film has no protective layer attached, and the protective layer has no resin layer (B) attached.
X: Even if attention is paid to the peeling speed and force, only the cover film cannot be peeled off. At this time, adhesion of the protective layer is recognized on the cover film, or adhesion of the resin layer (B) is recognized on the protective layer surface.

(14) Adhesiveness between cover film and protective layer The state of adhesion in the thermocompression bonding step during the production of the photosensitive resin structure was evaluated. ○ is desirable, × has a problem in use.
○: The protective layer can be uniformly applied to the cover film, and the cover film does not peel from the protective layer in the thermocompression bonding step.
X: When the protective layer is applied to the cover film, repellency and spots are generated and cannot be uniformly applied. Or a part of cover film peels from a protective layer at a thermocompression bonding process.

(15) Resolution For the evaluation in which the cover film was peeled off on the exposure machine in the photosensitive resin structure, and an image of a line number of 133 Line / inch, a dot of 1% density, and a concave line of 500 μm width was incorporated on the protective layer. A negative film is uniformly adhered in a vacuum, irradiated with a 350 W ultraviolet lamp for 10 minutes, and then developed at 25 ° C. with a solvent-based processing solution (a mixture of tetrachloroethylene / n-butanol = 3/1 (volume ratio)). did. After drying, the depth of the concave line having a width of 500 μm of the obtained printing plate for flexographic printing was measured with a depth microscope, and the depth of 100 μm or more was regarded as acceptable (◯).

<Manufacture of acid-modified polyolefin resin aqueous dispersion for manufacturing resin layer (B) of cover film>
[Aqueous dispersion E-1]
Using a stirrer equipped with a heat-resistant 1 liter glass container with a heater, 60.0 g of “Bondyne LX-4110” (manufactured by Arkema, maleic anhydride-modified polyolefin resin), 90.0 g of IPA (sum) Kogaku Pharmaceutical Co., Ltd.), 3.0 g of TEA (Wako Pure Chemical Industries, Ltd.) and 147.0 g of distilled water were charged into a glass container. And it stirred for 30 minutes, setting the rotational speed of a stirring blade to 300 rpm, maintaining system temperature at 140-145 degreeC. Then, it put on the water bath and cooled to room temperature (about 25 degreeC), stirring with a rotational speed of 300 rpm. Furthermore, pressure filtration (air pressure 0.2 MPa) was performed with a 300-mesh stainless steel filter (wire diameter 0.035 mm, plain weave). As a result, a milky white uniform acid-modified polyolefin resin aqueous dispersion E-1 was obtained.

[Aqueous dispersion E-2]
Using “Bondyne HX-8210” (manufactured by Arkema, maleic anhydride-modified polyolefin resin) as the acid-modified polyolefin resin, the same operation as in the production of the aqueous dispersion E-1 was performed, and the acid-modified polyolefin resin aqueous dispersion Body E-2 was obtained.

[Aqueous dispersion E-3]
Using “Bondyne HX-8290” (manufactured by Arkema, maleic anhydride-modified polyolefin resin) as the acid-modified polyolefin resin, the same operation as in the production of the aqueous dispersion E-1 was performed, and the acid-modified polyolefin resin aqueous dispersion Body E-3 was obtained.

[Aqueous dispersion E-4]
Using a stirrer equipped with a heat-resistant 1-liter glass container with a heater, 60.0 g of “Bondyne AX-8390” (manufactured by Arkema, maleic anhydride-modified polyolefin resin), 100.0 g of NPA (Japanese Kogyo Pharmaceutical Co., Ltd.), 2.5 g of TEA (Wako Pure Chemical Industries, Ltd.) and 137.5 g of distilled water were charged in a glass container. The stirring speed was 300 rpm, the system temperature was kept at 120 ° C., and stirring was performed for 20 minutes. Then, it cooled to room temperature (about 25 degreeC), stirring with air cooling with the rotational speed of 300 rpm. Furthermore, pressure filtration (air pressure 0.2 MPa) was performed with a 300-mesh stainless steel filter (wire diameter 0.035 mm, plain weave). As a result, a milky white uniform polyolefin resin aqueous dispersion E-4 was obtained.

[Aqueous dispersion E-5]
Using a stirrer equipped with a heat-resistant 1-liter glass container with a heater, 60.0 g of “Primacol 5980I” (manufactured by Dow Chemical Co., acrylic acid-modified polyolefin resin), 16.8 g of TEA, and 223 .2 g of distilled water was charged into a glass container. And it stirred for 30 minutes, setting the rotational speed of a stirring blade to 300 rpm, maintaining system temperature at 140-145 degreeC. Then, it put on the water bath and cooled to room temperature (about 25 degreeC), stirring with a rotational speed of 300 rpm. Furthermore, pressure filtration (air pressure 0.2 MPa) was performed with a 300 mesh stainless steel filter (wire diameter 0.035 mm, plain weave) to obtain a slightly cloudy aqueous dispersion E-5. At this time, almost no resin remained on the filter.

[Aqueous dispersion E-6]
30.0 g of Lexpearl EAA “A210K” (manufactured by Nippon Polyethylene Co., Ltd., acrylic acid-modified polyethylene resin), 105.0 g of NPA (sum) Kogaku Pharmaceutical Co., Ltd.), 7.8 g of TEA (Wako Pure Chemical Industries, Ltd.), and 157.2 g of distilled water were charged into a glass container, and the rotation speed of the stirring blade was 300 rpm. The system temperature was kept at 170 ° C. and stirred for 30 minutes. After cooling to room temperature (about 25 ° C.) while stirring at a rotational speed of 300 rpm, pressure filtration (air pressure 0.2 MPa) with a 300-mesh stainless steel filter (wire diameter 0.035 mm, plain weave) is used to produce a slightly cloudy aqueous solution. Dispersion E-6 was obtained. At this time, almost no resin remained on the filter.

  Table 1 shows the composition and physical properties of the acid-modified polyolefin resin used for the production of the aqueous dispersions E-1 to E-6. The composition and physical properties of the obtained aqueous dispersion are shown in Table 2.

  As shown in Table 1, the acid-modified polyolefin resin “Bondaine LX-4110” used for the aqueous dispersion E-1, the acid-modified polyolefin resin “Bondaine LX-8210” used for the aqueous dispersion E-2, Used for the acid-modified polyolefin resin “Bondaine HX-8290” used for the dispersion E-3, the acid-modified polyolefin resin “Bondaine AX-8390” used for the aqueous dispersion E-4, and the aqueous dispersion E-6. The acid-modified polyolefin resin “Lex Pearl EAA A210K” was suitable for the present invention in the range of 1 to 10% by mass of the acid-modified component. On the other hand, the acid-modified polyolefin resin “Primacol 5980I” used in the aqueous dispersion E-5 had an acid-modified component exceeding 10% by mass and was not suitable for the present invention.

<Manufacture of support film (A)>
As the support film (A), a predetermined commercially available film or a polyester film described below was used.

[Creation of polyester film (A-1)]
On the corona-treated surface of a biaxially stretched polyester resin film (“Embret SA-100” manufactured by Unitika, thickness 100 μm, Sa 0.037 μm), a urethane-based adhesive (Takelac A-525 / Takenate A- manufactured by Mitsui Chemical Polyurethanes) 52 two-pack type) was applied, and the applied film was dried for 10 seconds with a hot air drier at 80 ° C., so that the adhesive coating amount was 3 g / m ² . The adhesive coated surface and a corona-treated surface of a biaxially stretched polyester resin film (“Embret PTHA-25”, unit thickness 25 μm, Sa 0.27 μm manufactured by Unitika Ltd.) are bonded together with a nip roll (nip condition 80 ° C.), The film wound and bonded was aged for 72 hours in an atmosphere of 40 ° C. to produce a laminate film.

[Creation of polyester film (A-2)]
On the corona-treated surface of a biaxially stretched polyester resin film (“Embret SA-100” manufactured by Unitika, thickness 100 μm, Sa 0.037 μm), a urethane-based adhesive (Takelac A-525 / Takenate A- manufactured by Mitsui Chemical Polyurethanes) 52 two-pack type) was applied, and the applied film was dried for 10 seconds with a hot air drier at 80 ° C., so that the adhesive coating amount was 3 g / m ² . The adhesive-coated surface and a corona-treated surface of a biaxially stretched polyester resin film ("Embret SM-25 (A)" manufactured by Unitika Ltd., thickness 25 μm, Sa 0.44 μm) are bonded together with a nip roll (nip condition 80 ° C. Then, the wound and bonded film was aged for 72 hours in an atmosphere at 40 ° C. to prepare a laminate film.

<Manufacture of cover film>
Experimental example 1
Polyvinyl alcohol (“VC-10” manufactured by Nihon Acetate / Poval) whose solid content is 50 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin aqueous dispersion E-1 and the acid-modified polyolefin resin solid content And an aqueous solution of an oxazoline compound (so that the solid content of the oxazoline compound is 5 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin solids). Nippon Shokubai Co., Ltd. “Epocross WS-500”, solid content concentration 40% by mass) was mixed to obtain a liquid. This liquid material was coated on a corona-treated surface of a biaxially stretched polyester resin film (“Embret SA-100” manufactured by Unitika Ltd., thickness 100 μm, Sa 0.037 μm) using a Mayer bar, and then 50 ° C. at 120 ° C. The film was dried for 2 seconds and subjected to aging treatment at 70 ° C. for 2 days to obtain a cover film having a 0.6 μm resin layer formed on the polyester film. Table 3 shows the physical properties of the obtained cover film.

Experimental Examples 2-5
Instead of the acid-modified polyolefin resin aqueous dispersion E-1 in Experimental Example 1, E-2 to E-5 were used. Otherwise, the same operation as in Experimental Example 1 was performed to obtain a cover film. Table 3 or Table 5 shows the physical properties of the obtained cover film.

Experimental Examples 6-9
A liquid material was obtained in the same manner as in Experimental Example 1 except that the amount of the aqueous solution of oxazoline compound “WS-500” was changed to the amount shown in Table 3 or Table 5. Using this liquid material, a cover film was obtained in the same manner as in Experimental Example 1. Table 3 or Table 5 shows the physical properties of the obtained cover film.

Experimental Example 10
An aqueous solution of an oxazoline compound (manufactured by Nippon Shokubai Co., Ltd., “Epocross”) so that the solid content of the oxazoline compound is 5 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin aqueous dispersion E-1 and the acid-modified polyolefin resin solids. WS-500 ", solid concentration 40% by mass) was mixed to obtain a liquid material. This liquid material was coated on the corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-100" manufactured by Unitika Ltd., thickness 100 µm) using a Mayer bar, and then dried at 160 ° C for 50 seconds. Aging treatment was performed at 70 ° C. for 2 days to obtain a cover film having a 0.6 μm resin layer formed on the polyester film. Table 3 shows the physical properties of the obtained cover film.

Experimental Examples 11-16
A liquid material was obtained in the same manner as in Experimental Example 1, except that the amount of polyvinyl alcohol (“VC-10” manufactured by Nippon Vinegar Poval Co., Ltd., polymerization degree 1,000) was changed to the amount shown in Table 3 or Table 4. Got. Using this liquid material, a cover film was obtained in the same manner as in Experimental Example 1. Table 3 or Table 4 shows the physical properties of the obtained cover film.

Experimental Example 17
A liquid material was obtained in the same manner as in Experimental Example 1 except that the polyvinyl alcohol was changed to “JC-40” (degree of polymerization: 4,000) manufactured by Nippon Vinegar Poval. Using this liquid material, a cover film was obtained in the same manner as in Experimental Example 1. Table 4 shows the physical properties of the obtained cover film.

Experimental Example 18
Instead of the oxazoline compound aqueous solution in Experimental Example 1, an aqueous dispersion of a carbodiimide compound was used. Specifically, an acid-modified polyolefin resin aqueous dispersion E-1 and an aqueous dispersion of a carbodiimide compound (manufactured by Nisshinbo Co., Ltd., “Carbodilite E-02”, solid content concentration 40% by mass) are mixed with an acid-modified polyolefin resin solid content 100. The carbodiimide compound solid content was mixed to 5 parts by mass with respect to part by mass to obtain a liquid material. Using this liquid material, a cover film was obtained in the same manner as in Experimental Example 1. Table 4 shows the physical properties of the obtained cover film.

Experimental Example 19
A cover film was obtained in the same manner as in Experimental Example 1, except that the polyester film (A-1) was used as the biaxially stretched polyester resin film and the polyester film (A-1) was coated on the PTHA surface (Sa 0.27 μm). It was. Table 4 shows the physical properties of the obtained cover film.

Experimental Example 20
Covered by the same operation as in Experimental Example 1 except that “Embret PET-12” (thickness 12 μm, Sa 0.029 μm) manufactured by Unitika Co., Ltd. was used as the biaxially stretched polyester resin film, and it was applied to the corona-treated surface of the film A film was obtained. Table 4 shows the physical properties of the obtained cover film.

Experimental Examples 21-24
A cover film was obtained by the same operation as in Experimental Example 1 except that the drying conditions after coating the resin layer (B) were changed to the conditions described in Table 4. Table 4 shows the physical properties of the obtained cover film.

Experimental Example 25
Instead of the acid-modified polyolefin resin aqueous dispersion E-1 in Experimental Example 1, E-6 was used. Otherwise, the same operation as in Experimental Example 1 was performed to obtain a cover film. Table 4 shows the physical properties of the obtained cover film.

Experimental Example 26
A liquid was obtained in the same manner as in Experimental Example 1 except that the aqueous oxazoline compound solution “WS-500” was not used. Using this liquid material, a cover film was obtained in the same manner as in Experimental Example 1. Table 4 shows the physical properties of the obtained cover film.

Experimental Example 27
The liquid material of the acid-modified polyolefin resin aqueous dispersion E-1 was coated on the corona-treated surface of a biaxially stretched polyester resin film ("Embret SA-100" manufactured by Unitika Ltd., thickness 100 µm) using a Meyer bar. Then, it was dried at 140 ° C. for 50 seconds and subjected to aging treatment at 70 ° C. for 2 days to obtain a cover film having a 0.6 μm resin layer formed on the polyester film. Table 5 shows the physical properties of the obtained cover film.

Experimental Example 28
An aqueous solution of an isocyanate compound (made by Daiichi Kogyo Seiyaku Co., Ltd.) so that the solid content of the isocyanate compound is 5 parts by mass with respect to 100 parts by mass of the acid-modified polyolefin resin aqueous dispersion E-1 and the acid-modified polyolefin resin solids. “E-37”, solid content concentration of 40% by mass) was mixed to obtain a liquid material. This liquid material was coated on a corona-treated surface of a biaxially stretched polyester resin film (“Embret SA-100” manufactured by Unitika Ltd., thickness 100 μm, Sa 0.037 μm) using a Meyer bar, and then 50 ° C. at 160 ° C. The film was dried for 2 seconds and subjected to aging treatment at 70 ° C. for 2 days to obtain a cover film having a 0.6 μm resin layer formed on the polyester film. Table 5 shows the physical properties of the obtained cover film.

<Manufacture of photosensitive resin composition>
Example 1
90 parts by weight of a polyamide-based hot melt “Macromelt 6900 (manufactured by Henkel)” and 10 parts by weight of a styrene butadiene block copolymer “Tuftec M1913 (manufactured by Asahi Kasei Co.)” The mixed polymer was prepared by kneading for a minute. Subsequently, this polymer was dissolved in a mixed solvent of isopropyl alcohol / toluene = 1/1 to prepare a solution having a concentration of 15% by weight. Next, this solution was applied to the resin layer (B) surface of the cover film obtained in Experimental Example 1 using a blade coater so that the coating amount after drying was 5 to 5.5 g / m ^2. And dried at 80 ° C. for 2 minutes to obtain a cover film coated with a protective layer.

Next, 70 parts by weight of Kraton DKX-405 (styrene-butadiene-styrene block copolymer manufactured by Kraton Polymer Co., Ltd.), 23 parts by weight of B-2000 (liquid polybutadiene manufactured by Nippon Petrochemical Co., Ltd.), 1,9-nonanediol diacrylate 7 1 part by weight, 1.5 parts by weight of 2,2-dimethoxy-2-phenylacetophenone and 0.3 parts by weight of 2,6-di-t-butyl-p-cresol were kneaded together with a heating kneader mill, and this photosensitive resin composition The product was superposed on the adhesive layer of a 125 μm thick biaxially stretchable and easily adhesive polyester film (Embret UVL-125, 125 μm thick, manufactured by Unitika). Furthermore, a cover film coated with a protective layer is overlaid thereon so that the coated surface of the protective layer is on the photosensitive resin side, and a hydraulic pressure of 200 kg / cm at 130 ° C. with a press machine using a 3.0 mm spacer. Press molding was performed for 4 minutes under the condition ² to obtain a photosensitive resin constituent for a relief printing plate. The thickness of the photosensitive resin composition layer after pressing was 3.0 mm.

Examples 2 to 23 / Comparative Examples 1 to 3
A photosensitive resin structure for letterpress printing was obtained in the same manner as in Example 1 except that the cover film obtained in the predetermined experimental example was used instead of the cover film used in Example 1.
Since the structure obtained in Example 21 had a large difference in thickness between the cover film and the base film, the obtained structure was slightly curled.
Since the structure obtained in Comparative Example 1 used a resin other than the modified polyolefin defined in the present invention as the resin layer (B), it became a cover film with high peel strength. Therefore, the cover film was firmly adhered to the protective layer, and when the cover film was peeled off, adhesion of the protective layer was observed on the cover film, and peelability from the protective layer was not expressed.
In the structure obtained in Comparative Example 2, since the amount of PVA blended in the resin layer (B) was too large, the amount of PVA blended in the resin layer (B) was large. Bad, partially thickened. Therefore, it could not be applied uniformly, and as a result, the adhesion with the protective layer was partially poor.
The structure obtained in Comparative Example 3 was a cover film having high peel strength because the amount of the crosslinking agent blended in the resin layer (B) was too large. Therefore, it became inferior to peelability with a protective layer.

Comparative Example 4
Instead of the cover film used in Example 1, a biaxially stretched polyester resin film ("Embret SA-100" manufactured by Unitika Ltd., thickness 100 µm, Sa 0.037 µm) was used, and a protective layer was formed on the corona-treated surface of the film. A photosensitive resin composition for letterpress printing was obtained in the same manner as in Example 1 except that was applied.
Since the resin layer (B) was not coated, a cover film having high peel strength was obtained. Therefore, it became inferior to peelability with a protective layer.

Comparative Example 5
A relief printing plate as in Example 1, except that a polyester film (A-2) was used instead of the cover film used in Example 1 and a protective layer was applied to the SM-25 surface of the film (A-2). A photosensitive resin constituent for printing was obtained.
Since the resin layer (B) was not coated, a cover film having high peel strength was obtained. Therefore, it became inferior to peelability with a protective layer. Moreover, since the surface roughness of the polyester film (A-2) is high, the surface roughness is transferred to the protective layer, and light is scattered in the exposure process, so that the image reproduction resolution is lowered.

Comparative Example 6
A photosensitive resin composition for letterpress printing was obtained in the same manner as in Example 1 except that a fluorine-coated release film (“Emblet FFT-100”, thickness: 100 μm, manufactured by Unitika) was used as the cover film.
Although a protective layer was coated on the surface coated with fluorine, repelling was observed and uniform coating was not possible.

Comparative Example 7
A photosensitive resin composition for letterpress printing was obtained in the same manner as in Example 1 except that a silicone-coated release film “Embret SC-125” having a thickness of 125 μm was used as the cover film.
Although a protective layer was coated on the silicone-coated surface, cissing was observed and uniform coating could not be achieved.

Comparative Example 8
A photosensitive resin composition for letterpress printing was obtained in the same manner as in Example 18 except that the cover film obtained in Experimental Example 27 was used instead of the cover film used in Example 18.
Since the resin layer B contains neither a cross-linking agent nor polyvinyl alcohol, the peel strength after treatment at a high temperature of 140 ° C. was high, and the film was inferior in peelability. Therefore, the peelability from the protective layer deteriorated.

Comparative Example 9
A photosensitive resin composition for letterpress printing was obtained in the same manner as in Example 8, except that the cover film obtained in Experimental Example 28 was used instead of the cover film used in Example 8.
The resin layer B uses an isocyanate compound as a cross-linking agent, and does not contain any of an oxazoline compound, a carbodiimide compound, or polyvinyl alcohol, so that the peel strength after treatment at a high temperature of 160 ° C. is high and the film is inferior in peelability. It became. Therefore, the peelability from the protective layer deteriorated.

1: Base film 2: Photosensitive resin composition layer 3: Protective layer 4: Cover film 20: Exposure part 41: Support film (A)
42: Resin layer (B)
50: Negative film

Claims (6)

A cover film that constitutes a part of the photosensitive resin structure for letterpress printing and is peeled off during plate making,
It has a resin layer on the surface, the resin layer contains an acid-modified polyolefin resin having an acid-modified component of 1 to 10% by mass, a crosslinking agent and / or polyvinyl alcohol, and the crosslinking agent is a carbodiimide compound and / or an oxazoline compound. Composed of
When the content of the crosslinking agent with respect to 100 parts by weight of the acid-modified polyolefin resin is X (parts by mass) and the content of polyvinyl alcohol is Y (parts by mass), the contents X and Y are expressed by the following relational expression (1) or ( 2) a cover film satisfying at least one of the above;
(1) 1 ≦ X ≦ 50 and 0 ≦ Y ≦ 1000;
(2) 0 ≦ X ≦ 50 and 5 ≦ Y ≦ 1000.   The cover film according to claim 1, wherein the resin layer is provided on a polyester film.   The total content of a silicone compound, a fluorine compound, a wax, and a surfactant in the resin layer is 1 part by mass or less based on 100 parts by mass of the acid-modified polyolefin resin. Cover film.   The peel strength between the resin layer and the adhesive is 0.5 to 4.3 N when the adhesive material using the acrylic adhesive on the resin layer surface of the cover film is measured by thermocompression bonding at 70 ° C. for 20 hours. It is / cm, The cover film in any one of Claims 1-3 characterized by the above-mentioned.   It has the structure laminated | stacked in order of the base film, the photosensitive resin composition layer, the protective layer, and the cover film in any one of Claims 1-4, and the cover film is so that the said resin layer may adjoin a protective layer A photosensitive resin composition for letterpress printing, wherein the photosensitive resin composition is laminated on.   The protective layer is a hydrogenated polyamide, alkyl cellulose, hydroxyalkyl cellulose, nitrocellulose, cellulose ester, a copolymer of monovinyl-substituted aromatic hydrocarbon and conjugated diene, and a copolymer of monovinyl-substituted aromatic hydrocarbon and conjugated diene 6. The photosensitive resin constituent for relief printing according to claim 5, comprising at least one polymer selected from the group consisting of reactants.

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