JP2890770B2 - Anti-adhesion layer composition for flexographic printing plates - Google Patents

Description

The present invention relates to an anti-adhesion layer composition used for flexographic printing plates.

(Prior Art) In the step of converting a photosensitive resin into a printing plate, a method of exposing the original film to a photosensitive layer of the photosensitive resin original plate in vacuum and exposing it to actinic rays is mainly used.

In recent years, in the field of business home printing, the demand for rubber-like flexible photosensitive resin letterpress has been increasing, and as a result, the photosensitive resin original plate tends to be softer.

The surface of the photosensitive layer of the master is usually tacky in many cases, and the lower the hardness of the master, the more the tackiness increases. If the tackiness is strong, uniform adhesion cannot be achieved when the original film is brought into close contact, and therefore, the reproducibility of the image deteriorates.
Further, when the original film is peeled off from the original plate after the exposure, there is a problem that the adhesion of the original film causes a peeling failure and both of them are damaged.

In order to solve such a problem, the most commonly used method is a technique of applying a thin film of a polymer having low adhesiveness to the surface of a photosensitive resin.

For example, JP-A-51-49803 (polyvinyl alcohol having a saponification degree of 90% or more), JP-A-52-110010 (polyvinyl alcohol having a polymerization degree of 800 or more and saponification degree of 70% to 90%), JP-A-54-68224 (water-soluble polymer) and JP-A-56-110941 (soluble polyamide) are known.

However, these methods have the following problems.

(1) When a polyvinyl alcohol thin film is provided, fine wrinkles are generated on the surface of the original plate when the cover film is peeled off or when the original plate is bent inward or outward during the plate making process. Wrinkles remain on the relief surface, resulting in uneven ink density of the printed matter.

(2) Among water-soluble polymers, non-crystalline polymers excluding polyvinyl alcohol having a saponification degree of 90% or more (for example, cellulose derivatives, vinyl polymer maleic acid copolymer, etc.) become tacky due to moisture absorption of the thin film. It rises remarkably, and hinders the adhesion of the target original film. or,
There are problems such as blocking in the manufacturing process of the thin film.

(3) Thin films other than the water-soluble polymer do not have humidity dependency, but in recent years, a type using water is mainly used for developing a photosensitive resin printing plate. Therefore, if the polymer is not a water-soluble or water-dispersible polymer, the step of removing the thin film before development is not preferable because the step of removing the thin film with an organic solvent that dissolves the thin film increases in advance.

By the way, when the photosensitive resin composition is for a flexographic printing plate, the photosensitive resin is more flexible and has high adhesiveness, so that a high demand for a non-adhesive coating layer is high. The problem of occurrence is easy to occur.

Therefore, for flexographic printing plates, a technique in which a release layer is further provided is disclosed in JP-A-57-208556, and a technique in which polyvinyl alcohol is mixed with a plasticizer to prevent wrinkles is disclosed in JP-A-2-113254. Have been.

However, the former application of the release agent not only increases the number of production steps, but also the application of a non-adhesive coating layer on the release agent tends to cause coat defects, and requires a high-level application technique. On the other hand, the latter coated layer of polyvinyl alcohol containing a plasticizer is susceptible to the influence of humidity, and there is a disadvantage that the applied layer becomes sticky due to moisture absorption under high humidity and the original non-adhesive purpose is lost.

(Problems to be Solved by the Invention) As described above, even in the prior art, at present, there is no water-developable and flexible anti-adhesion material for a photosensitive resin plate.

The problem of wrinkles is particularly serious.For example, if the peeling of the cover film is interrupted once and the peeling is resumed, linear wrinkles occur at the point where the peeling was interrupted. Although it is required that the machine be peeled, there is a chance that the peeling is interrupted due to a peeling operation error or the like, and it is difficult to completely prevent the occurrence of wrinkles. Further, when the photosensitive resin laminate from which the cover film has been peeled off is deformed into a concave or convex shape, when it is returned to a normal flat state, wrinkles are generated in the anti-adhesive layer. For the photosensitive resin laminate after the cover film is peeled off, it is necessary to move the photosensitive resin laminate as much as possible.However, it may be unavoidable that the photosensitive resin laminate must be moved. Moving is not easy.

Therefore, in the present invention, the purpose of the present invention is to provide a water-dispersible polymer, which has good adhesion to the original film, and which is free from the occurrence of fine wrinkles even if the original plate is bent, and at the same time gives a thin film for anti-adhesion which is not affected by humidity. I have.

(Means for Solving the Problems) The present inventors have conducted intensive studies on the anti-adhesion layer composition to solve the above-mentioned drawbacks, and as a result, have finally completed the present invention.

That is, the present invention is an anti-adhesion layer composition for flexographic printing plates containing polyvinyl alcohol and glycerin in an amount of 4% by weight or more and less than 8% by weight based on the total composition.

Polyvinyl alcohol used in the present invention,
Regardless of the synthesis method, the degree of saponification is preferably 97% or more, particularly preferably 98% or more. 97% saponification degree
If it is less than 1, the moisture resistance becomes poor, which is not preferred.

The content of glycerin in the composition of the present invention may be in the range of 4% by weight or more and less than 8% by weight, more preferably 5% by weight or more and less than 8% by weight based on the composition of the anti-adhesion layer. is there.

The composition of the present invention is used as an anti-adhesion layer in a photosensitive resin laminate of a flexographic printing plate. The laminate comprises at least an adhesive layer, a photosensitive resin layer, an anti-adhesion layer and a cover film on a support. The production method is to apply an anti-adhesion layer to the cover film in advance, and prepare an adhesive layer applied to the support in advance, and then press the two layer materials around the photosensitive resin composition. The method of laminating by a method is usually performed.

Here, the dimensional stability and heat resistance of the cover film,
A polyethylene terephthalate film is most suitable from the viewpoint of mechanical performance, but a single or laminated coated material such as polyethylene, polypropylene, polystyrene or any other releasable material can be used. The surface of the cover film may be smooth, but more preferably a so-called mat shape having a surface roughness of 5 μ or less.

When the composition of the present invention is applied on the cover film, polyvinyl alcohol is made into an aqueous solution of 1 to 15%, preferably 2 to 5%, and a part of glycerin is scattered in a drying step after application, so that excess It must be blended. The blending amount is 10 to 100 with respect to polyvinyl alcohol
% By weight, preferably 20 to 70% by weight, but slightly varies depending on the drying temperature, the amount of air for drying, and the drying time. However, the glycerin in the anti-adhesion layer after drying was 4% by weight as described above.
And less than 8% by weight.

In addition, in addition to polyvinyl alcohol and glycerin, various surfactants may be added to the composition of the present invention in order to improve coatability on a cover film.

The thickness of the anti-adhesion layer after drying is 0.1 to 10 μm, preferably 2 to 5 μm.

Next, the photosensitive resin composition in the photosensitive resin laminate in which the composition of the present invention is used is prepared by dissolving or swelling a polymer and an ethylenically unsaturated monomer (and / or) in water or an aqueous developer. It can be applied to those obtained by a method comprising a polymer and a photoinitiator. For example, there are JP-A-60-211451 and JP-A-60-173055.

In addition to the above-mentioned photosensitive resin composition, such as those described in a patent application filed separately, that is, (A) a hydrophobic polymer having a glass transition temperature of 5 ° C. or lower,
(B) a hydrophilic polymer, (C) an ethylenically unsaturated compound, (D) a solvent in which the solubility of the component (B) is higher than that of the component (A), and (E) a photopolymerization initiator,
A photosensitive resin composition characterized in that the content of the component (B) is smaller than that of the component (A). In a photosensitive resin printing original plate and a printing plate, a hydrophobic polymer is contained in the photosensitive resin layer. The photosensitive resin composition is characterized in that particles surrounded by a phase containing a hydrophilic polymer as a main component are present as a dispersed phase.

The hydrophobic polymer having a glass transition temperature of 5 ° C. or lower as the component (A) includes those used as general-purpose elastomers. For example, a polymer obtained by polymerizing a conjugated diene-based hydrocarbon, a copolymer obtained by polymerizing a conjugated diene-based hydrocarbon and a monoolefin-based unsaturated compound, a polymer containing no conjugated diene-based hydrocarbon, and the like can be given. Can be

As conjugated diene hydrocarbons, 1,3-butadiene,
Isoprene, chloroprene and the like are used. The conjugated diene-based hydrocarbon may be used alone or in combination of two or more.

Monoolefinically unsaturated compounds include styrene,
α-methylstyrene, 0-methylstyrene, m-methylstyrene, P-methylstyrene, acrylonitrile, methacrylonitrile, vinyl chloride, vinylidene chloride, acrylamide, methacrylamide vinyl acetate, acrylate, methacrylate, etc. are used. You.

A polymer obtained by polymerizing a conjugated diene-based hydrocarbon,
Or, as a copolymer obtained by polymerizing a conjugated diene-based hydrocarbon and a monoolefin-based unsaturated compound, a butadiene polymer, an isoprene polymer, a chloroprene polymer,
Styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-chloroprene copolymer, acrylonitrile-butadiene copolymer, acrylonitrile-isoprene copolymer, acrylonitrile-chloroprene copolymer, methyl methacrylate-butadiene copolymer Methyl methacrylate-isoprene copolymer, methyl methacrylate-chloroprene copolymer, methyl acrylate-butadiene copolymer, methyl acrylate-isoprene copolymer, methyl acrylate-chloroprene copolymer, acrylonitrile-butadiene- Styrene copolymer, acrylonitrile-isoprene-styrene copolymer, acrylonitrile-chloroprene-styrene copolymer and the like can be mentioned.

Examples of the polymer containing no conjugated diene-based hydrocarbon include an elastomer containing a specific amount of chlorine and a non-conjugated diene-based hydrocarbon.

Those showing rubber elasticity have a chlorine content of 50 to 10% by weight
And a polymer having a glass transition temperature (hereinafter referred to as Tg) of 5 ° C. or less, for example, polymerization of a chlorine atom-containing monomer or other monomer capable of copolymerizing with a chlorine atom-containing monomer. Obtained from copolymerization with the body. It can also be obtained by reacting chlorine or an active substance containing chlorine with a polymer containing no chlorine atom. Specifically, the following can be mentioned. Epichlorohydrin polymer, epichlorohydrin-ethylene oxide copolymer, epichlorohydrin-propylene oxide copolymer and / or epichlorohydrin rubber which is a copolymer of these with allyl glycidyl ether [Epichromer manufactured by Osaka Soda Kogyo Co., Ltd.
vich Co., Ltd. HYDRIN, Nippon Zeon Co., Ltd. GECHRON, Zeospan, Hevcules Co., Ltd. HERCLOR], chlorinated polyethylene [Showa Denko Co., Ltd., Eraslen, Osaka Soda Kogyo Co., Ltd. Daiisorac, Hoechst Co., Ltd.] ) HORTALITZ,
DOWCPE manufactured by Dow Chemical Co., Ltd.), vinyl chloride copolymer,
Examples thereof include vinylidene chloride, chlorinated polypropylene, and chlorinated ethylene-propylene rubber. These polymers may be used alone or in combination of two or more. The chlorine content of the polymer is from 10 to 50% by weight, preferably from 15 to 40% by weight. If the chlorine content is out of this range, the flexibility of the polymer is impaired or the thermal stability is impaired. Is too hard or is liable to be colored. Since the conjugated diene-based hydrocarbon polymer containing a chlorine atom or its copolymer contains a carbon unsaturated bond in the main chain, there is a drawback that the chemical stability such as weather resistance is inferior to the case of only a saturated bond. Further, since the physical properties of the photosensitive resin composition after light irradiation greatly depend on the properties of the component (A) in the present invention,
It is preferable that the component (A) is essentially a rubber elastic body. Therefore, its Tg needs to be 5 ° C. or less, especially −
10 ° C. or lower is preferred.

In the present invention, not only the polymer as the component (A) but also an elastomer having good compatibility and ozone resistance, for example, an acrylic rubber or a polyurethane elastomer may be blended.

The content of the component (A) in the entire composition is preferably 20% by weight or more, particularly 30% by weight, in consideration of the physical properties and shape retention of the printing plate.
% Or more, and from the viewpoint of photopolymerizability,
% By weight, particularly preferably 70% by weight or less.

The hydrophilic polymer as the component (B) means water or a polymer containing water as a main component and soluble or swelling (dispersing) in a developing solution containing an alkaline aqueous solution, an acidic aqueous solution, an organic solvent, or a surfactant. -CO ₂ M group, -SO ₃ M group,
(M represents a hydrogen atom, the periodic table I, II, III group element, amine, ammonium) -NH _2, having a hydrophilic group such as -OH, and is no polymer cross-linking by a chain. Examples of such hydrophilic polymers include polyvinyl alcohol (PVA), a general-purpose resin such as carboxymethyl cellulose, a diene rubber obtained by copolymerizing a (meth) acrylic acid and a diene compound, a liquid polybutadiene modified with maleic anhydride, also particularly effective as a backbone -COOM (M represents a hydrogen atom, a I, II, III group elements of the periodic table, amine, shows the ammonium) and a 50 to 50,000 equivalents / 10 ⁶ g with polymer, the periodic table Examples of Group I, II, and III elements include alkali metals such as sodium, potassium, and lithium, alkaline earth metals such as calcium and magnesium, boron, and aluminum. Incidentally it is difficult to develop in neutral water poor affinity for water in -COOM groups less than 50 equivalents / 10 ⁶ g in the present invention, whereas 50,000 equivalents / 1
And when it is more than 0 ⁶ g, because the water-based ink is inferior undesirable.

Specific examples of the hydrophilic polymer include -COOM group-containing polyurethane, -COOM group-containing polyurea urethane, -COOM group-containing polyester, -COOM group-containing epoxy compound, -COOM
Group-containing polyamic acid, -COOM group-containing acrylonitrile-
Butadiene copolymer, -COOM- group-containing styrene-butadiene copolymer, -COOM group-containing polybutadiene, polyacrylamide, sodium polyacrylate, polyvinyl alcohol (PVA) carboxymethyl cellulose (C
(MC) hydroxyethylcellulose (HEC) methylcellulose (MC), polyethylene oxide, polyethyleneimine, and derivatives of such compounds can be used, but are not limited thereto.

Compounds used to neutralize at least a part of the carboxyl group contained in the hydrophilic polymer include lithium hydroxide, potassium hydroxide, hydroxides of alkali metals such as sodium hydroxide, lithium carbonate, Alkali metal carbonates such as potassium carbonate and sodium carbonate, alkali metal alkoxides such as potassium t-butoxide and sodium methoxide, hydroxides of polyvalent metals such as calcium hydroxide, magnesium hydroxide and aluminum hydroxide, aluminum isopro Polyvalent metal alkoxides such as poxide, triethylamine, tri-n
Tertiary amines such as propylamine, diethylamine,
Secondary amine ethylamine such as di-n-propylamine,
Primary amines such as n-propylamine, cyclic amines such as morpholine, amino group-containing (meth) acrylates such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, ammonium carbonate, etc. , Ammonium salts, and the like.
These may be used alone or in combination of two or more.

The hydrophilic polymer may have a polyoxyalkylene chain as a hydrophilic portion other than the -COOM group, and may contain an ethylenically unsaturated group so as to act as a crosslinking agent.

As the component (B), for example, a polymer having a hydrophilic group such as a hydroxyl group, an amino group, a sulfonic acid group and / or a polyoxyalkylene chain may be used in addition to the hydrophilic polymer.

The content of the component (B) in the entire composition is preferably 5 to 50% by weight, and more preferably 7 to 50% by weight in consideration of aqueous developing property and water-resistant ink property.
Particularly preferred is 40% by weight, more preferably 7-30% by weight.

It is essential that the content of the component (B) in the entire composition is lower than that of the component (A), and if the content is higher than the component (A), the water-resistant ink becomes poor.

The component (C) contains at least one ethylenically unsaturated compound.
This compound contains a terminal ethylenic group, and this compound is capable of forming a high molecular polymer by free radical-initiated chain propagation addition polymerization. Suitable ethylenically unsaturated compounds are unsaturated esters of polyols, especially α
Such esters with methylene carboxylic acid, for example ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, glycerol diacrylate, 1,3-propanediol di (meth)
Acrylate, 1,4-butanediol di (meth) acrylate, 1,2,4-butanetriol tri (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, 1,6-mexanediol di (meth) ) Acrylate, trimethylolpropane tri (meth) acrylate diallyl phthalate, fumaric acid diethyl ester, maleic acid dibutyl ester and the like; and N-substituted maleimide compounds such as N-methylmaleimide, N-ethylmaleimide and N-laurylmaleimide; Oligonitrile butadiene di (meth) acrylate, oligonitrile urethane (meth) acrylate, oligourethane di (meth) acrylate, oligobutanediene (meth) acrylate, oligobutadiene urethane di (meth) acrylate (Meth) acrylate. It may be used in combination alone.

The content of the component (C) in the composition is preferably from 1 to 50% by weight, and if it is less than 1% by weight, the photopolymerizability is hindered, so that no image remains after development. Conversely, if it is more than 50% by weight, shape retention will be impaired. Further, the plate after light irradiation is hard and brittle, which is not suitable for a flexographic printing plate material, which is not preferable. More preferably, it is 5 to 40% by weight.

As a solvent in which the solubility of the component (B), which is the component (D), is higher than the solubility of the component (A), a solvent having a high polarity can be mentioned. That is, the solvent swells, disperses, and dissolves the hydrophilic polymer (B) component, but has a small degree of swelling with respect to the hydrophobic polymer. Specific examples of such a solvent include water,
Examples of the water include alcohols having 1 to 5 carbon atoms. Examples of the water include surfactants such as alkyl benzene sulfonate, sodium alkyl naphthalene sulfonate, sodium alkyl sulfonate, and alkyl ether sulfonate; fatty acids; Lithium oxide, potassium hydroxide,
It may contain sodium hydroxide, sodium borate, sodium carbonate, sodium acetate, magnesium acetate or salts thereof. Examples of the alcohol include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, t-butyl alcohol, pentyl alcohol, and neopentyl alcohol.
Further, as long as it satisfies the requirement of (D), ester-based, ketone-based, and amide-based solvents can be used.
Specifically, ethyl acetate, butyl acetate, isobutyl acetate,
Methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, methyl butyl ketone, formamide,
Dimethylformamide, dimethylacetamide and the like. These solvents can be used alone or in combination as a mixed solvent.

The amount of the component (D) contained in the entire composition is limited in view of the performance of the flexographic printing plate, and the range is 0.001% by weight to 5% by weight based on the total composition, preferably 0.001% by weight.
% To less than 2.0% by weight. When the content of the component (D) exceeds 5% by weight based on the total composition, the original plate before photopolymerization becomes soft, which causes cold flow, plastic deformation, and the like. As a relief, deformation of projections (a so-called low spot) occurs, and a clear image cannot be obtained.

Examples of the (E) component photopolymerization initiator include benzophenones, benzoins, acetophenones, benzyls, benzoin alkyl ethers, benzylalkyl ketals, anthraquinones, and thioxanthones. Specifically, benzophenone, chlorobenzophenone, benzoin, acetophenone, benzyl benzoin, methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, benzyl diethyl ketal, benzyl diisopropyl ketal, anthraquinone, 2-chloroanthraquinone Thioxanthone, 2-chlorothioxanthone and the like. These are preferably contained in the composition in an amount of 0.01 to 5% by weight. If it is less than 0.01%, the photopolymerization initiation ability is hindered, and 5%
If the amount is too large, the curing depth cannot be obtained by the light itself, and the image tends to be chipped by the development, which is not preferable.
More preferably, it is 0.1 to 3% by weight.

In order to simply prevent thermal polymerization without suppressing the photocrosslinking reaction, in addition to the requirements (A) to (E), (F)
The thermal polymerization inhibitor may be contained in an amount of 0.001 to 5% by weight. Useful thermal polymerization inhibitors include, for example, hydroquinone, hydroquinone monoethyl ether, catechol, pt
-Butylcatechol, 2,6-di-t-butyl-p-cresol and the like.

Other plasticizers in the photosensitive resin composition include liquid polybutadiene rubber, liquid polyacrylonitrile butadiene rubber, liquid polystyrene butadiene rubber, liquid isoprene rubber, and the like, liquid rubber and polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene, etc. Or a fine powder of silica, diatomaceous earth or the like having a relatively low molecular weight.

Using the photosensitive resin plate composition, as a method of preparing a printing original plate and a printing plate, a suitable solvent for the above components in any order, for example, tetrahydrofuran, dioxane, methyl ethyl ketone, toluene cyclohexanone,
Solvent that swells, disperses, and dissolves hydrophilic polymers such as chloroform and water, alcohol, etc. (D)
It can be prepared by dissolving and mixing the components under ordinary conditions, removing the solvent, and then heating and press-bonding to a suitable support, for example, a film of polyester, polyethylene, polypropylene or the like. On a surface different from the support, a cover film coated with a polyvinyl alcohol coating film containing glycerin as the composition of the present invention so as to be a photosensitive resin surface is pressure-bonded to form a photosensitive resin laminate.

Ultraviolet rays used for curing the photosensitive resin printing plate precursor obtained by the above method are effective at a wavelength of 150 to 500 mμ, particularly those in a wavelength region of 300 to 400 mμ, and a low-pressure mercury lamp is used as a light source. High pressure mercury lamps, carbon arc lamps, ultraviolet fluorescent lamps, chemical lamps, xenon lamps, zirconium lamps and the like are desirable. The photosensitive resin printing original plate is exposed to ultraviolet light by irradiating a negative film having a transparent image with the light source using the above light source, and after exposing the image, non-image portions not exposed are removed using a developing solution at about 25 ° C. to 45 ° C. By doing so, the printing plate of the present invention having a clear relief image can be obtained.

As the developer, pH 5.0 to 9.0 containing water for daily use in general
Is most suitable, and may contain an alkaline compound such as sodium hydroxide or sodium carbonate, a surfactant, a water-soluble organic solvent, or the like as a main component of the water. As the above-mentioned surfactant, sodium alkylnaphthalenesulfonate, sodium alkylbenzenesulfonate and the like are most suitable, and in addition, anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants are preferable. Can be used.

The developing device used in the present invention is immersed or sprayed while the brush is in contact with the photosensitive resin printing plate precursor exposed to the developing solution. Upon contact with the developing solution, the polyvinyl alcohol anti-adhesion layer comprising the composition of the present invention swells and zeits, is easily removed by brushing, and then the non-exposed portions are removed.

After washing off the developer adhering to the plate after development with water,
Further, the adhered water is wiped off and dried. Drying is performed with forced air or infrared rays, but the conditions are not particularly limited. The dried plate is completely cured by a so-called post-exposure operation in which the plate is further exposed by the light source used for exposure.

Examples Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.

 In the examples, “parts” means “parts by weight”.

In the present invention, the content of glycerin in the polyvinyl alcohol coating film was measured by the following method.

The cover film on which the polyvinyl alcohol coating film is formed is cut into a square of 30 cm × 30 cm, the coating film is peeled off, and the weight is measured with a precision balance. Put the weighed coating film in a 20 ml volumetric flask, add pure water to it, and leave it at room temperature for 1 night.
The glycerin efflux peak height is determined at 50μ under the following conditions: The amount of glycerin is calculated from a previously prepared calibration curve, and the glycerin content (% by weight) converted from the weight of the first coating film is determined.

Example 1 Example 1 illustrates the production of a polyvinyl alcohol anti-adhesion layer mixed with glycerin of the present invention and the production of a cover film thereof.

To 964.3 parts of pure water, 25.0 parts of Gohsenol AH-26 (saponification degree 97.0 to 98.8% manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was added, and 90 parts were added.
Stirred at C for 2 hours, then cooled to room temperature. To this solution, 10.7 parts of glycerin was slowly added with stirring, and the mixture was further stirred for 30 minutes. Next, this solution was subjected to 125 μm polyethylene terephthalate (E-5000 manufactured by Toyobo Co., Ltd.) at a speed of 6 m / min.
Was coated with a reverse roll and dried at 110 ° C. The anti-adhesion layer thus obtained had a thickness of 2.3 μm and a glycerin content of 6.0%.

Example 2 A photosensitive resin composition was prepared in the following manner.

Solution prepared by dissolving 21.8 parts of hexamethylene diisocyanate, 15.4 parts of dimethylolpropionic acid, 7.6 parts of polytetramethylene glycol (PG-100 manufactured by Nippon Polyurethane Industry Co., Ltd.), and 1.0 part of di-n-butyltin dilaurate in 300 parts of tetrahydrofuran Was placed in a flask equipped with a stirrer, and the flask was heated to 65 ° C. while continuing stirring to continue the reaction for 3 hours. In a separate container, acrylonitrile-butadiene oligomer containing terminal amino groups (Hycar ATBN
A solution prepared by dissolving 55.3 parts of X1300 × 16 (produced by Ube Industries, Ltd.) in 100 parts of methyl ethyl ketone was added to the above one flask while stirring at room temperature. The obtained polymer solution was dried under reduced pressure to remove tetrahydrofuran and methyl ethyl ketone to obtain a polymer having a number average molecular weight of 21,000. Next, a solution obtained by dissolving 4.8 parts of lithium hydroxide in 100 parts of methyl alcohol was added to a solution of 100 parts of the polymer dissolved in 100 parts of methyl ethyl ketone while stirring at room temperature, and further stirred for 30 minutes to obtain a hydrophilic polymer. [I] was obtained.

10 parts of the above hydrophilic polymer [I] and chlorinated polyethylene (H-135 manufactured by Osaka Soda Co., Ltd.) 4 as the hydrophobic polymer
5 parts, styrene-butadiene rubber (SBR1507 manufactured by Nippon Synthetic Rubber Co., Ltd.) 15 parts, butadiene oligoacrylate (PB-
A Kyoeisha Oil & Fat Co., Ltd. 28.5 parts, 1 part of benzyldimethylketanol (Irgacure 651, Ciba-Geigy Co., Ltd.) and 0.5 part of hydroquinone monomethyl ether are dissolved and dispersed in 40 parts of toluene and 10 parts of water, and heated using a kneader. Te kneaded and degassed at 105 ° C., the resulting photosensitive resin composition 105 ° C. in a heat press machine at a pressure of 100 kg / cm ^3, 125
m between the polyester film having a thickness of m and the polyester film having the anti-adhesion layer obtained in Example 1 by heating and pressing for 1 minute so that the anti-adhesion layer is in contact with the photosensitive resin.
A 2.8mm sheet (printing plate) was created.

When the topmost polyester film was peeled off to leave a polyvinyl alcohol film on the photosensitive resin layer, and the surface was observed, it showed a smooth and mirror-like surface.

Further, when the polyester film was peeled off, it was interrupted halfway, and then the peeled surface had linear wrinkles at the place where the interruption was made. When left in this state at room temperature for 5 minutes, the linear wrinkles disappeared and the surface became a mirror-like surface.

Next, a negative film having an image on this plate is adhered on it, and a mercury lamp (manufactured by Dainippon Screen Co., Ltd.) is used.
Exposure was performed for m ² for 5 minutes. After removing the negative film, developing with a brush at 40 ° C for 15 minutes in neutral water containing 2% by weight of sodium alkylnaphthalenesulfonate resulted in an image pattern with a relief (printing plate) having a depth of 1.2 mm. Was. This image pattern faithfully reproduced the image of the negative film used. The obtained relief is
The transferability of the ink was good, and a clear image was shown.

Comparative Example 1 A cover film having an anti-adhesion layer was prepared in the same manner as in Example 1 except that glycerin was not added. When a photosensitive resin laminate was prepared from the cover film by the method described in Example 2, and the polyester film was peeled off,
The surface had wrinkles similar to the surface of the human skin. Example 2
Exposure and development were carried out in the same manner as in Example 1. As a result, wrinkles remained on the surface of the photocured image, and ink transfer irregularities were also observed on the printed matter.

In addition, when the peeling of the polyester film was interrupted and then peeled, linear wrinkles were observed at the point of interruption. In this state, it was left at room temperature, but even if left overnight, the wrinkles and linear wrinkles on its surface remained and did not disappear, and a normal mirror-like surface could not be obtained. .

Example 3 In Example 1, a polyethylene terephthalate film was replaced with a chemical mat film (TC-500 manufactured by Toyo Cross Co., Ltd.).
0) A polyvinyl alcohol anti-adhesion layer was formed in the same manner as in Example 1 except that a thickness of 95 μm was used. The obtained anti-adhesion layer has a thickness of 2.1μ and a glycerin content of 5.1% by weight.
Met. Using this coated film, a photosensitive resin laminate was formed in the same manner as in Example 2 and the chemical mat film was peeled off. The polyvinyl alcohol coating film remained on the photosensitive resin layer, and a uniform mat-like surface was formed. was gotten.

Comparative Example 2 In Example 1, 2.5 g of a chemical mat film (Toyo Cloth Co., Ltd., TC-5000, thickness: 95 μ) was added without adding glycerin.
A μ-thick polyvinyl alcohol anti-adhesion layer was prepared in the same manner as in Example 1. Using this coated film, a photosensitive resin laminate was prepared in the same manner as in Example 2 and the chemical mat film was peeled off. The peel strength was 60 g / cm, and peeling was not easy. Wrinkles were generated on the surface of the photosensitive resin layer which could be peeled off, and the wrinkles and the linear wrinkles generated by interruption of the peeling did not disappear even when left.

Comparative Example 3 Gozenol GH-17 [Nippon Synthetic Chemical Industry Co., Ltd.
86.5-89 mol% of polyvinyl alcohol]
It was completely dissolved by heating and stirring at 80 ° C in 4.1 parts of pure water.
Add 0.88 polyethylene glycol 0.88 in this solution
Parts were mixed and dissolved. From this solution by wire bar
On 125μ thick polyethylene terephthalate film
Containing 8% polyethylene glycol with a thickness of 2.5μ
An adhesion preventing layer was formed. This viscosity was obtained by the method described in Example 2.
An anti-adhesion layer is laminated on the photosensitive resin layer to form a cover film.
Polyethylene terephthalate film
However, compared to the case without polyethylene glycol
Although the occurrence of wrinkles was reduced, fine wrinkles were
Isn't a mirror-like surface obtained when phosphorus is mixed?
Was.

The same method was used to examine the mixing ratio of polyethylene glycol, which is less likely to cause wrinkles when peeled off by increasing the mixing amount of polyethylene glycol. The effect was finally exhibited when the mixing ratio of polyethylene glycol was 15%. The level of wrinkles that caused no trouble during printing was obtained.
However, when the polyvinyl alcohol anti-adhesion layer having a mixing ratio of polyethylene glycol of 15% or more was left at 25 ° C. and 80% relative humidity for 24 hours or more, the adhesiveness of the coating film was observed due to moisture absorption.

(Effect of the Invention) The anti-adhesion layer composition of the present invention having the above-described structure increases flexibility by containing glycerin in polyvinyl alcohol, and at the same time, requires a small peeling force when peeling a polyester film (cover film). This has the effect of making it easier to peel off with less force. In addition, the releasability of the cover film is preferably as easy as possible in the plate making process, but it is preferable that the cover film is less likely to be peeled during the production, packaging, transportation and cutting of the photosensitive resin original plate into a desired size. Therefore, the peel strength when making a plate is 30 to 2 g / cm, preferably 10 to 2 g / cm.
It is desirable that the distance be within cm, but the mixing of glycerin also has the effect of developing this peel strength.

It is known that polyhydric alcohols are compatible with polyvinyl alcohol, and particularly that glycerin significantly improves the flexibility of the polyvinyl alcohol film, but it is surprising that it has an effect on the releasability from the polyester film.

Another effect obtained by mixing glycerin is that when the cover film of the photosensitive resin laminate is peeled, the anti-adhesion layer remaining on the photosensitive resin layer can peel the cover film without generating wrinkles. . What is more effective is that the wrinkles disappear or recover even once they occur.

Further, since the anti-adhesion layer composition of the present invention is not affected by humidity at all, it greatly contributes to practical use of a flexographic printing plate.

Continuation of the front page (56) References JP-A-52-110010 (JP, A) JP-A-56-36511 (JP, A) JP-A-58-10732 (JP, A) JP-A-60-91348 (JP, A) JP-A-61-17148 (JP, A) JP-A-2-113254 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03F 7/11

Claims (1)

(57) [Claims] An anti-adhesion layer composition for flexographic printing plates comprising polyvinyl alcohol and glycerin in an amount of 4% by weight to less than 8% by weight based on the total composition.