JPH11160857A - Solvent resistant flexible letterpress - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible letterpres superior in solvent resistance and capable of being coated with a solvent type ink containing a polar solvent or a coating material to form a printing or design or pattern plate by forming the surface of a plate with polyurethane. SOLUTION: The plate surface (printing plate surface or coating surface and the like) is formed with the polyurethane polymer composed essentially of urethane bonds, and generally obtained by reaction of an active hydrogen compound with polyisocyanate. The active hydrogen compound is a compound having >=2 of an active hydrogen-containing-group in the molecule, such as hydroxyl or carboxyl or amino group. Preferable active hydrogen compound is various kinds of polyols, alcohol having >=2 hydroxyl groups in one molecule. The obtained solvent-resistant flexible letterpress is superior in resistance to polar solvents because of the printing surface made of polyurethane, and since the flexibility of the plate is not impaired, it can be used for flexography.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solvent-resistant flexible relief printing plate, and more particularly to a solvent-resistant flexible relief printing plate suitable for printing of metallic materials or decorative coating.

[0002]

2. Description of the Related Art In the case of printing a large number of identical patterns at low cost, a gravure offset printing method has been conventionally used. With the gravure offset printing method, a cylindrical metal plate is used as a plate cylinder, that is, a gravure cylinder, an offset blanket cylinder is interposed between the gravure cylinder and the impression cylinder, and the plate pattern is once transferred to the surface of the offset blanket cylinder, Is further printed on a printing medium.

In other words, the circumferential surface of the offset blanket cylinder comes into contact with the circumferential surface of the gravure cylinder, while also contacting the printing body. In the gravure offset printing method, first, the ink stored in the ink container is supplied to the circumferential surface of the gravure cylinder, and then the ink adhering to portions other than the concave portions of the circumferential surface is, for example, After being removed using a doctor blade or the like, the ink adhering to the concave portion is transferred to the circumferential surface of the transfer roll, and the ink adhering to the circumferential surface of the transfer roll is transferred to the printing medium. .

As described above, in the gravure offset printing method, since the offset rubber cylinder made of a soft material is used between the gravure cylinder and the printing material, the ink is brought into close contact with the printing material made of the hard material evenly. Can be.

[0005] In the gravure offset printing method, the plate material is metal, and rubber having excellent solvent resistance can be used as the offset rubber cylinder. Therefore, the gravure offset printing method is also suitable for use in printing a large amount at low cost using a solvent type ink containing a polar solvent.

For example, in printing or painting a metal material which has been printed or painted in advance or not, such as a can used for beverages and foods, it is necessary to use a vehicle having excellent adhesion to metals and the like. In some cases, a polar solvent is often contained in a coloring agent such as ink to uniformly dissolve these vehicles. Therefore, conventionally, a gravure offset printing method using an offset rubber cylinder having excellent solvent resistance has been mainly used for printing or painting a metal material.

On the other hand, a thin steel plate whose surface is painted,
BACKGROUND ART A metal plate such as an aluminum plate (pre-coated metal) has been widely used as a building material for exterior, a building material for interior, a material for electric products, and the like. In recent years, among such materials, for example, metal siding materials used for house building materials, which have been painted with a design property, have become widespread. Such a coated metal plate is usually coated by a gravure offset printing method using a paint as a coloring agent.

As described above, the gravure offset printing method is excellent for use in printing the same design in large quantities at low cost, but is not suitable for use in which the design is frequently changed. This is because since the plate material is metal, it is necessary to re-etch the metal in order to change the design, which increases the plate manufacturing cost.

In particular, in recent years, the design of products has been increased in design, various designs, small lots, and shortening of product life have been advanced, and it has been often required to change the design of metal materials in a short period of time. It is desired to improve productivity and reduce production cost.

Further, the gravure cylinder made of a steel roll is heavy and bulky, so that there is a problem that handling such as plate change is not easy and a considerable space is required for storing the gravure cylinder.

Further, the concave portion of the gravure cylinder is usually formed by corroding the peripheral surface of the gravure cylinder plated with copper using chromic acid or the like. Waste liquid is discharged. For this reason, there is a problem that it takes time to treat the harmful waste liquid containing chromic acid and the like.

A flexographic printing method is an example of a printing method in which the pattern can be easily changed. The flexographic printing method is a printing method in which a liquid ink or a paint is placed on the surface of a flexible relief printing plate made of an elastic body, and this is transferred to a printing substrate.
In the present specification, the “surface of the relief printing plate” may be referred to as a “plate surface”. In this specification, the terms “ink” and “paint” are used together, but are not intended to be strictly distinguished, and both are concepts that are included in a coloring agent including a coloring agent, a resin, and a solvent.

In this printing method, since the plate material is an elastic material, it has an inking transition characteristic similar to that of an offset rubber cylinder for gravure offset printing. In recent years, since a photosensitive resin plate material is generally used, the plate is remade. It doesn't cost much. Therefore, if the flexographic printing method can be used also for the printing of the pre-coated metal, it is possible to easily cope with the change of the design in a short period of time at low cost.

However, a flexible letterpress generally used in the flexographic printing method is composed of a rubber elastic material having a high flexibility. These rubber elastic bodies generally have poor resistance to polar solvents in inks or paints used for printing metal materials.

Therefore, when such a flexible relief printing plate is used for printing precoated metal, the printing surface immediately swells and the printing plate is destroyed. That is, the flexible letterpress has poor resistance to polar solvents, and it has been conventionally difficult to perform printing using a solvent-type ink by a flexographic printing method.

[0016]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method of printing or printing using a solvent type ink or paint having excellent solvent resistance and containing a polar solvent. An object of the present invention is to provide a flexible letterpress that can be designed and painted.

[0017]

SUMMARY OF THE INVENTION The present invention provides a solvent-resistant flexible letterpress having a plate surface (printed surface or painted surface, etc.) formed of polyurethane, thereby achieving the above object. .

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The polyurethane referred to in the present invention is
A polymer mainly composed of urethane bonds. Polyurethane is generally obtained by reacting an active hydrogen compound with a polyisocyanate.

The active hydrogen compound refers to a compound having two or more active hydrogen-containing groups such as a hydroxyl group, a carboxyl group, an amino group, and an active methylene group in a molecule. Active hydrogen compounds include polyesters, polyethers, polyols obtained by hydrogenation of carbon monoxide-olefin copolymers (polyketones), their formaldehyde-modified polymers, phenol-aldehyde polycondensates, aldehyde-polyol polycondensates, bisphenol A and Examples include epoxy resins obtained by polycondensation with epichlorohydrin, polythioethers, polyesteramides obtained from dicarboxylic acids and diamines or amino alcohols, and mixtures thereof.

Preferred active hydrogen compounds for use in the present invention are various polyols. The polyol refers to an alcohol having two or more hydroxyl groups in one molecule. For example, polyethers, polyesters, glycols, castor oil derivatives and the like are all polyols.

Preferred polyols for use in the present invention are acrylic polyols, polyester polyols, composites and mixtures thereof, and the like. Particularly preferred are acrylic polyols, polyester polyols, and acrylic polyester polyols which are composites thereof. This is because these have a hydroxyl group in the molecular chain, so that the crosslink density is higher than that of polyethers having a hydroxyl group only at the molecular end, and the solvent resistance is improved.

The polyol has a molecular weight of 100 to 50,000.
0, preferably 1000 to 200,000, hydroxyl equivalent 1
It is preferable to adjust to 0 to 300, preferably 30 to 200. When the molecular weight of the polyol is less than 100, the surface strength and the solvent resistance of the obtained flexible letterpress decrease. If it exceeds 500,000, it becomes difficult to form a relief printing plate surface, and its physical properties also deteriorate. The hydroxyl equivalent of the polyol is 1
If it is less than 0, the solvent resistance of the obtained flexible letterpress decreases. When it exceeds 300, the surface physical properties such as the flexibility of the obtained flexible letterpress decrease.

Specifically, acrylic polyols include:
Number average molecular weight (Mn) 3000-7000, weight average molecular weight (Mw) 6000-14000, Mw / Mn 1.5
-2.5 acrylic copolymers; polyester polyols include, for example, polyester copolymers obtained by polycondensation of polyols with dicarboxylic acids composed of saturated fatty acids, unsaturated fatty acids, aromatic acids, and the like; and other acrylic-modified polyesters A polyol or the like can be used as the polyol of the present invention.

The acrylic polyol is obtained by copolymerizing a hydroxyl group-containing acrylic monomer and another ethylenically unsaturated monomer by a conventional method. The hydroxyl group-containing acrylic monomer is not particularly limited. For example, hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate And the like.

The ethylenically unsaturated monomer copolymerizable with the above-mentioned hydroxyl group-containing acrylic monomer is not particularly restricted but includes, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl ( Alkyl (meth) acrylates such as meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate; aromatics such as styrene and vinyltoluene Vinyl compounds; vinyl compounds such as acrylonitrile, vinyl acetate, acrylic acid, and methacrylic acid; epoxy-containing monomers such as glycidyl (meth) acrylate; dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate; Meth) acrylamide, N- (meth) acrylamide, N, N- butoxymethyl (meth) acrylamide, and an amino group-containing monomers and acrylamides such as N- methylacrylamide. These may be used alone or in combination of two or more.

As the acrylic polyol, a soft segment such as a lactone-modified monomer such as ε-caprolactone-modified acrylic monomer is used in order to impart flexibility to the coating film and to enhance the workability of the applied metal material. Those using a contained monomer, that is, a lactone-modified acrylic polyol are preferred.

Some of the monomers containing the soft segment are commercially available. For example, 2-hydroxyethyl (meth) acrylate / ε-caprolactone adduct and polyalkylene glycol mono (meth) acrylate are commercially available as Praxel FA series and Praxel FM series (all manufactured by Daicel Chemical Industries, Ltd.).

The polyester polyol is a polycondensate of an acid component mainly composed of a polycarboxylic acid and an alcohol component mainly composed of a polyhydric alcohol.

The acid component is not particularly restricted but includes, for example, terephthalic acid, isophthalic acid, phthalic acid, 2,6-
Aromatic dicarboxylic acids such as naphthalenedicarboxylic acid and 2,7-naphthalenedicarboxylic acid and anhydrides thereof; aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid Acids and the like can be mentioned.

In addition to the above, lactones such as γ-butyrolactone and ε-caprolactone; hydroxycarboxylic acids corresponding thereto; aromatic oxymonocarboxylic acids such as p-oxyethoxybenzoic acid; trimellitic acid; It may contain a trivalent or higher valent polycarboxylic acid such as trimedic acid and pyromellitic acid.

The alcohol component is not particularly restricted but includes, for example, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,5-hexanediol, diethylene glycol, triethylene glycol, Ethylene glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, bisphenol A alkylene oxide adduct, bisphenol S alkylene oxide adduct; 1,2-propanediol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 2,3-pentanediol, 1,4-pentanediol, 1,4-hexanediol, 2,5-hexanediol, 3-methyl-1,5 -Pentanediol, 1,2-dodeca Diol, the side chains such as 1,2-octadecanediol and aliphatic glycol having.

In addition to the above, tri- or higher-valent polyhydric alcohols such as trimethylolpropane, glycerin and pentaerythritol may be used as trace components.

The polyester polyol resin may be combined with another component, for example, an acrylic component, if necessary.

Such polyols are available from Nippon Polyurethane Co. under the trade names "Nipporan 194" and "Nipporan 12".
5 "and" Acrylic polyol H ", and are available from Dainippon Ink and the like under the trade name" Acrydec A801 ".

The polyisocyanate is a compound having two or more isocyanate groups in one molecule. The polyisocyanate may be, for example, any of aliphatic, alicyclic, aromatic, and aromatic-aliphatic types. Isocyanate (TDI), 4,4′-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HMDI), lysine diisocyanate,
4'-methylenebis (cyclohexyl isocyanate), methylcyclohexane-2,4-diisocyanate, methylcyclohexane-2,6-diisocyanate, 1,3- (isocyanatomethyl) cyclohexane, isophorone diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, dianimate Sidin diisocyanate, phenyl diisocyanate, halogenated phenyl diisocyanate, methylene diisocyanate, ethylene diisocyanate, butylene diisocyanate, propylene diisocyanate, octadecylene diisocyanate, 1,5-naphthalene diisocyanate, polymethylene polyphenylene diisocyanate, triphenylmethane triisocyanate, naphthylene diisocyanate , 3-phenyl-2-
Ethylene diisocyanate, cumene-2,4-diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-ethoxy-1,3-phenylene diisocyanate, 2,4′-diisocyanatodiphenyl ether, 5,6-dimethyl-1 , 3-Phenylene diisocyanate, 4,4'-diisocyanatodiphenyl ether, benzidine diisocyanate, 9,10-anthracene diisocyanate, 4,4'-diisocyanatodibenzyl, 3,3-dimethyl-4,4'-di Isocyanatodiphenyl, 2,6-dimethyl-4,4'-diisocyanatodiphenyl, 3,3-dimethoxy-4,4'-diisocyanatodiphenyl, 1,4-anthracenediisocyanate, phenylenediisocyanate, 1,4 -Tetramethylene diisocyanate 1,10-decane diisocyanate, diisocyanates such as 1,3-cyclohexylene diisocyanate; isocyanurates of these diisocyanates, biuret, adduct; 2,4,6-triisocyanate, 2,
Triisocyanates such as 4,4'-triisocyanatodiphenyl ether; HMDI trimers; and polyisocyanate prepolymers obtained by reacting a polyol with an excess of diisocyanate.

Examples of the polyol used for preparing the polyisocyanate prepolymer include pentaerythritol, dipentaerythritol, trimethylolpropane, trimethylolethane, ditrimethylolpropane, glycerin, diglycerin and the like.
Furthermore, alkylene oxide-modified or lactone-modified polyols obtained by adding ethylene oxide, propylene oxide, ε-caprolactone, γ-butyrolactone or the like to these can also be mentioned.

For use in the present invention, aliphatic polyisocyanates are particularly preferred. Such an aliphatic polyisocyanate, a polyisocyanate prepolymer obtained by reacting an aliphatic polyisocyanate with an aliphatic polyol such as pentaerythritol, dipentaerythritol, trimethylolethane, trimethylolpropane and ditrimethylolpropane , And a multimer of an aliphatic polyisocyanate.

Examples of preferred aliphatic polyisocyanates for forming the polyisocyanate prepolymer include:
HMDI. Examples of preferred aliphatic polyols for forming the polyisocyanate prepolymer include trimethylolpropane. A particularly preferred polyisocyanate prepolymer is a polyisocyanate prepolymer obtained by reacting trimethylolpropane with HMDI.

Examples of preferred multimers of aliphatic polyisocyanate include aliphatic polyisocyanate 3
And HMDI trimers.

The aliphatic polyisocyanate described here is commercially available, and is available from Nippon Polyurethane Co. under the trade names "Coronate HL" and "Coronate HX".

The operation of reacting the active hydrogen compound with the polyisocyanate to form a polyurethane may be performed by any method conventionally known to those skilled in the art. For example, a polyurethane can be obtained by mixing the two, applying the mixture, and allowing the mixture to stand at room temperature. Depending on the reactivity of the active hydrogen compound and the polyisocyanate used, a suitable amount of a commonly used catalyst such as dibutyltin dilaurate may be added,
The reaction temperature may be raised and lowered.

The ratio between the active hydrogen compound to be reacted and the polyisocyanate is 1/20 to 1 / 0.5, preferably 1/20, as the equivalent ratio of the active hydrogen-containing group to the isocyanate group.
It is 10 to 1/1. If the equivalent ratio of both is less than 1/20, the residual isocyanate groups in the polyurethane will increase and the polyurethane will react with moisture in the air, and the surface strength of the relief plate, such as flexibility, will decrease. When the ratio is more than 1 / 0.5, the amount of active hydrogen-containing groups remaining in the polyurethane increases, so that the resulting flexible relief plate has reduced resistance to polar solvents.

The solvent-resistant flexible relief printing plate of the present invention is sufficient if the surface of the relief printing plate in direct contact with the ink or paint, that is, the plate surface is formed of polyurethane, and is formed of polyurethane up to the inside which is not in direct contact with the ink or paint. You don't have to. Therefore, as a preferred embodiment of the solvent-resistant flexible letterpress of the present invention, a solvent-resistant flexible letterpress having a support plate material layer and a surface protective layer formed thereon, wherein the support plate material layer is an elastic material And a solvent-resistant flexible relief printing plate in which the surface protective layer is formed of polyurethane.

In this embodiment, as the support plate material layer,
It is preferable to use an elastic plate material (flexible letterpress) which has been conventionally used in the flexographic printing method as it is. This is because a flexible relief plate manufactured by a conventional method can be utilized, which is advantageous in terms of simplicity of operation and cost reduction.

When a polyurethane layer is provided on the support plate material layer, the surface of the plate used as the support plate material layer has
Applying a surface protective composition containing an active hydrogen compound and a polyisocyanate as main components; and curing the applied surface protective composition to form a surface protective layer;
It is preferable to use a method including

As the active hydrogen compound and the polyisocyanate used in the surface protective composition, those described above are used.
The mixing ratio is the same as the above-mentioned reaction ratio. If necessary, the surface protective composition may contain a suitable amount of a catalyst (for example, the above-mentioned dibutyltin dilaurate) usually used for the reaction between the active hydrogen compound and the isocyanate. The surface protective composition may further contain various additives usually used for realizing easy handling as the coating composition and easy coating.

[0047] Such additives include volatile solvents commonly used as diluents for coating compositions. For example, hydrocarbon, ether, acetal, ketone, aldehyde, ester, polyhydric alcohol and the like.

In one embodiment of a method of providing a polyurethane layer on the plate surface of a plate material used as a support plate material layer, first,
An active hydrogen compound, a polyisocyanate, a catalyst, an additive and the like are mixed to prepare a surface protective composition having a viscosity suitable for coating. Generally, the viscosity at room temperature is 1 to 1000 cps, preferably 10 to 100 cps. For that purpose, the solid content must be usually 0.1 to 10% by weight, preferably 1 to 8% by weight.

The application of the surface protective composition to the plate surface of the plate material may be performed by dipping, air spray coating, brush coating, or the like. Generally, the dry film thickness is 1 to 15 μm, preferably 3 μm.
Coating is performed with a coating amount of 10 to 10 μm.

Next, the applied surface protective composition is dried and cured to form a surface protective layer. Generally, at room temperature
The surface protection composition is left to dry and cure for 7 days, but may be heated if necessary.

The plate material used as the support plate material layer may be formed of any conventionally known material. Affinity with polyurethane is good, and particularly preferable as such a relief material is, for example, a polymerizable polymer or chloroprene rubber, ethylene-chloroprene rubber, butyl rubber, silicone rubber, fluorine rubber, acrylic rubber,
Flexible formed of materials such as polysulfide rubber, urethane rubber, natural rubber, butadiene rubber, isoprene rubber, foams of these rubbers, or reaction products of these rubber components with photocurable monomers, photocuring initiators, etc. It is letterpress.

When a polymer of a polymerizable monomer or a rubber, or a foam of a rubber or a reaction product of a rubber component and a polymerizable monomer is used as a letterpress material, the uneven shape of the letterpress is formed by ultraviolet rays or a laser beam. And its durability is also enhanced. In particular, a composition comprising a rubber component and a photopolymerizable monomer is suitable for providing a rubber layer with a concavo-convex shape that imparts a design property by photopolymerization by ultraviolet irradiation.

That is, at least one of ultraviolet rays and a laser beam (hereinafter referred to as “ultraviolet rays”) is applied to the surface of the photosensitive plate material by an original image having a design property (for example, an original image of a base material). ) To cause photo-curing of the light-receiving portion of the photosensitive plate material (the portion to which ultraviolet light or the like has actually been applied), and then develop the photosensitive plate material (for example, Brushing, etc.) to remove the uncured (uncured) parts to form recesses, and leave the photocured parts to form protrusions,
It is possible to create a three-dimensional image having a surface with an uneven shape corresponding to the original image.

The photosensitive printing plate used in the present invention as a relief printing plate is:
Any material that has been used for printing plates and other photoresists may be used, but basically a liquid plate such as an acrylic monomer or unsaturated polyester or a photosensitive plate material of the same type containing a large amount of liquid monomer components is more preferable. It is preferably used. Specifically, as the liquid plate, US Pat. No. 4,209,581
And U.S. Pat. No. 4,234,676. The photosensitive plate material is preferably of a water developing type, and examples thereof include those described in JP-A-61-223395 and JP-A-61-246742.
Further, it may be of a solvent developing type, for example, U.S. Pat. Nos. 4,323,637, 4,234,676, 4,264,705 and JP-A-52-64301. Are described. More specifically, the same type of photosensitive printing plate contains at least a thermoplastically processable polymer, a photopolymerizable ethylenically unsaturated monomer, and a photopolymerization initiator.

Examples of thermoplastically processable polymers include polyethylene, polypropylene, polyvinyl chloride,
Styrene polymer, especially styrene-diene copolymer, butadiene and / or isoprene polymer, butadiene / acrylonitrile copolymer (nitrile rubber), elastomeric polyurethane, polyamide, polyimide, polyamideimide, (meth) acrylate polymer, Vinyl chloride / vinyl acetate copolymers, vinylidene chloride polymers, vinyl esters-especially vinyl acetate or vinyl propionate polymers, polyvinyl alcohol and others.

Based on the type of thermoplastically processable polymer used, general processing conditions known per se for the polymer, such as temperature loading, plasticization, addition of auxiliaries, etc., should be taken into account. . As polymers that can be processed thermoplastically, in addition to polyurethane and vinyl alcohol polymers,
Elastomeric rubbery polymers, such as, in particular, one-component polymers of butadiene and isoprene, copolymers of butadiene and isoprene with one another and with other copolymerizable monomers, such as nitrile rubbers, such as polymerized acrylonitrile 15 to A butadiene / acrylonitrile copolymer having 45% by weight, a nitrile rubber having a carboxyl group, a nitrile rubber containing vinyl chloride and a multiblock copolymer comprising styrene, butazine and / or isoprene, for example, an AB-2 block copolymer; ABA-3 block copolymers, ABC-3 block copolymers (these are described, for example, in DE-A-294 2 183), star-shaped block copolymers, partially or Examples include fully hydrogenated block copolymers.

The photopolymerizable ethylenically unsaturated monomer is a compound having an ethylenically unsaturated group. Specific examples include unsaturated carboxylic esters (e.g., n-butyl (meth)
Acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, methoxy polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, phenoxy polyethylene glycol Mono (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate,
Triethylene glycol di (meth) acrylate, diallyl itaconate, glycerol di (meth) acrylate,
Glycerol tri (meth) acrylate, 1,3-propylene glycol di (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, 1,2,4-butanetriol tri (meth) acrylate, glycerol polypropylene glycol tri ( (Meth) acrylate,
1,4-benzenediol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, tetramethylene glycol di (meth) acrylate, 1,5-pentanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate ) Acrylate), unsaturated amides (e.g., methylenebis (meth) acrylamide, ethylenebis
(Meth) acrylamide, 1,6-hexamethylenebis (meth) acrylamide, diethylenetriaminetris (meth) acrylamide, N- (hydroxymethyl) acrylamide, N- (hydroxymethyl) methacrylamide, N
-(Β-hydroxyethyl) acrylamide, N- (β-
(Hydroxyethyl) methacrylamide, N, N′-bis (β
-Hydroxyethyl) acrylamide, N, N'-bis (β
-Hydroxyethyl) methacrylamide), divinyl esters (e.g., divinyl adipate, divinyl phthalate), acrylated or methacrylated urethanes (derived from hydroxyalkyl acrylates or hydroxyalkyl methacrylates and isocyanate compounds), diacrylic or dimethacrylic esters, or Examples include diepoxy polyethers derived from aromatic compounds and polyalcohols such as bisphenol or novolak compounds. One or more of these compounds may be used, and generally water-insoluble monomers are preferred.

Examples of photopolymerizable initiators include benzene ethers (eg, benzoin isopropyl ether, benzoin isobutyl ether), benzophenones (eg, benzophenone, methyl-o-benzoyl benzoate), xanthones (eg, xanthone, thioxanthone) , 2-chlorothioxanthone), acetophenones
(E.g., acetophenone, trichloroacetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone), benzyl, 2-
Ethyl anthraquinone, methyl benzoyl formate,
2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-4'-isopropyl-isopropiophenone, 1-hydroxycyclohexylphenyl ketone and the like. These may be used alone or in combination.

The above-mentioned photosensitive plate material may further include, if necessary,
A core-shell microgel, a microgel, and / or a compound containing a basic nitrogen atom such as a partially internally crosslinked copolymer may be blended.

As specific examples, for example, partially crosslinked copolymers of butadiene / methacrylic acid / divinylbenzene / methyl methacrylate, styrene / isoprene / styrene copolymer, maleic acid monoester-modified isoprene polymer, N, N -A rubber molded product composed of diethylaminopropyl methacrylamide, lauryl methacrylate and 2-ethyleneanthraquinone (for example, trade name "Flexid B-067", hardness after curing JIS A 60 °, 1.
7 mm: Nippon Paint Co., Ltd.), styrene / isoprene /
Rubber molded product containing styrene copolymer as a main component (for example,
Trade name “Sirel PLS” manufactured by Du Pont).

In addition, a rubber molded article for acrylic liquid casting (trade name "APR": manufactured by Asahi Kasei Kogyo Co., Ltd.) can also be used.

The obtained solvent-resistant flexible relief printing plate of the present invention has a printed surface formed of polyurethane and has excellent resistance to polar solvents. Specific examples of such polar solvents include ketones such as isophorone and cyclohexanone, cellosolves, esters, and alcohols. In addition, the solvent-resistant flexible letterpress of the present invention has excellent resistance to non-polar solvents such as hydrocarbon solvents such as toluene, xylene and petroleum spirit.

Further, the flexibility of the plate is not impaired. Therefore, if the solvent-resistant flexible relief printing plate of the present invention is used, flexographic printing can be performed with a solvent-type ink or paint containing a polar solvent. That is, printing can be performed by applying an ink or paint containing a polar solvent to the printing surface of the solvent-resistant flexible relief printing plate of the present invention, and transferring the applied ink or paint to a printing body. By doing so,
For example, printing or painting of a precoated metal or the like, which has been conventionally performed by the gravure offset printing method, can also be performed by the flexographic printing method.

When printing or painting an article by flexographic printing, the solvent-resistant flexible relief printing plate of the present invention is wound around a printing roll shaft to form a transfer roll.

As shown in FIG. 1, the transfer roll 100 used in the present invention comprises a flexible relief layer 101 and a printing roll shaft 102. Transfer roll 100
The hardness of the flexible letterpress layer 101 can be arbitrarily set according to the object to be coated, but is preferably in the range of JISC 30 ° to A80 °. May be a multilayer.

Further, as shown in FIG. 2, a foam layer 203 is provided between the flexible letterpress layer 201 and the printing roll shaft 202.
Can be provided. By providing the foam layer 203, it is possible to efficiently transfer a coating film having a design to a substrate such as a wall material that is not smooth due to the elasticity of the foam layer 203. Such a foam layer is sufficient if it is an elastic layer that is rich in rebound resilience and low in residual stress.
A layer of polyurethane of 500 kg / m ³ ,
In particular, a material having a skin surface is preferable in terms of adhesiveness.

As shown in FIG. 3, a support layer 304 can be provided between the foam layer 303 and the printing roll shaft 302. The support layer 304 includes a flexible letterpress layer 301,
It is sufficient if it has a role of supporting the foam layer 303 and the like and is excellent in mechanical strength, thermal stability, dimensional stability, and the like.
For example, polyethylene terephthalate resin (PET) may be mentioned. The foam layer 303 can be set to any thickness in consideration of whether the base material has a smooth surface or an uneven surface, and is 1 to 30 mm, preferably 5 to 25 mm.

Further, as shown in FIG. 4, a plastic sheet layer 405 may be provided between the flexible letterpress layer 401 and the foam layer 403. Plastic sheet layer 40
No. 5 is effective at the time of processing after forming the concave-convex shape on the flexible letterpress layer 401 and needs to be excellent in handleability, dimensional stability, etc., and bonds the interface between the flexible letterpress layer 401 and the foam layer 403. It preferably has a role of causing As such a plastic sheet layer, a polymer compound such as polyolefin or polyurethane is suitable, and in particular, polyethylene terephthalate resin (PET)
Is preferred.

Incidentally, between the layers constituting the transfer roll,
An adhesive layer may be provided to prevent a displacement that may occur between the layers. Further, a sleeve made of glass reinforced plastic or the like may be mounted on a printing roll shaft (shaft), and the above-described layers may be mounted on the sleeve.

Preferred as an article to be printed or painted by the method of the present invention is a metal plate. As a metal plate,
For example, a hot-dip galvanized steel sheet, an electro-galvanized steel sheet, an alloyed galvanized steel sheet, a zinc-aluminum alloy-plated steel sheet, an aluminum-plated steel sheet, a stainless steel sheet, a cold-rolled steel sheet, or an aluminum sheet can be used. The shape or shape of such a metal plate may be either a cut plate or a coiled metal plate. The metal plate may be a pre-coated metal plate whose surface is pre-coated.

The paint used in the roll coater preferably has a No. 4 Ford cup viscosity of 10 to 300 seconds. This paint contains at least one of an acrylic resin, an alkyd resin, a polyester resin, a silicon-modified polyester resin, a silicon-modified acrylic resin, a vinyl chloride resin, and a fluororesin as a resin component,
If necessary, an amino resin or a blocked polyisocyanate may be contained as a resin vehicle. Further, this paint is more preferably a weather-resistant paint.

In addition, an active energy ray-curable paint may be used. As an active energy ray-curable paint,
Generally, a polymer, an oligomer, a monomer or the like having a radical polymerizable double bond in its structure as a main component as a coating film-forming component, and if necessary, a non-reactive polymer, an organic solvent, or a wax. And other additives can be used. The active energy ray includes an electron beam, an ultraviolet ray, and the like, and a preferable film-forming resin includes a resin having an acrylate-based functional group.

Further, it may contain coloring pigments, extender pigments and other rust preventive pigments. As such a pigment,
For example, titanium dioxide, phthalocyanine blue, phthalocyanine green, quinacdrine, indanthrone, isoindolinone, berylene, anthrapyrimidine, carbon black, benzimidazolone, graphite, yellow iron oxide, coloring pigments such as red iron oxide, clay, carbonic acid Extenders such as calcium and aluminum silicate;

As the rust preventive pigment, various rust preventive pigments can be used, but it is preferable to use chromate rust preventive pigments such as strontium chromate, calcium chromate, barium chromate and zinc chromate. .

Further, various additives such as a curing catalyst such as dodecylbenzene sulfonic acid, a benzophenol-based ultraviolet absorber, a surface conditioner such as silicone and an organic polymer, a sagging agent and a thickener can be added. . These additives improve the performance of paints and coatings. However, if the amount of these additives is too large, repelling may occur during the formation of the coating film, or the interlayer adhesion may be deteriorated. Further, a solvent may be appropriately added for viscosity adjustment (workability).

As described above, in the flexographic printing method, the pattern can be changed more easily and easily than in the gravure offset printing method, so that it is possible to cope with printing of a small number of lots at low cost. More preferably, such a flexible relief printing plate is more flexible than an offset blanket cylinder used in gravure offset printing, and thus has excellent adaptability to the shape of a printing medium. Therefore, by using the solvent-resistant flexible relief printing plate of the present invention, high-quality printing or decorative coating can be performed even on a printing body having irregularities such as an embossed precoated metal.

[0077]

The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto.

Example 1 40 parts of styrene, 30 parts of isobornyl methacrylate,
And an acrylic polyol having a number average molecular weight of 5,000 and a hydroxyl equivalent of 80 comprising 30 parts of n-butyl acrylate (N
V 65%, butyl acetate / xylol solvent 35%) 10 g
And 28 g of a reaction product of 1 mol of trimethylolpropane and 3 mol of HMDI (75% NV, 25% ethyl acetate solvent, "Coronate HL" manufactured by Nippon Polyurethane Co., Ltd.) (equivalent ratio of hydroxyl group to isocyanate group 1/1) ), 123 g of xylene and 123 g of butyl acetate were added to obtain a surface protective composition (solid content: 10%).

A photosensitive resin plate material of 80 mm × 80 mm composed of N, N-diethylaminopropyl methacrylamide / lauryl methacrylate / 2-ethyleneanthraquinone (hardness after curing JIS A60 #, Nippon Paint Co., Ltd. “Flexidose B-067”) Was exposed and developed in accordance with the printing pattern to produce a flexible relief printing plate.

The surface of the flexible relief printing plate was brush-coated with the surface protective composition at a coating amount of 0.32 g / 64 cm ² in solid content. This was left at room temperature for 7 days, and the applied surface protective composition was dried and cured to obtain a solvent-resistant flexible relief printing plate.

Performance Evaluation Coatability of the Surface Protective Composition to the Flexible Relief (Wetting) The printed surface of the resulting solvent-resistant flexible relief was visually inspected for repellency. Table 1 shows the results. When there was a cissing, it was evaluated as "x", and when there was no cissing, it was evaluated as "o".

Bending Resistance of Solvent-Resistant Flexible Letterpress A solvent-resistant flexible letterpress was prepared with the printing surface facing outward.
Along the surface of 0 mmR, the presence or absence of cracks or cracks was visually observed. Table 1 shows the results. When there was a crack or crack, it was evaluated as "x", and when it was not, it was evaluated as "o".

Solvent Resistance of Solvent-Resistant Flexible Letterpress The solvent-resistant flexible letterpress was immersed in isophorone for 24 hours, and the difference in weight change, plate thickness change (%), and hardness (JIS A) before and after immersion was measured. It was measured. Table 1 shows the results. The smaller the rate of change, the better the solvent resistance of the solvent-resistant flexible relief printing plate.

Adhesion of Polyurethane Layer The solvent-resistant flexible relief plate was immersed in isophorone for 24 hours, taken out and left for 4 hours. Thereafter, a 60 ° cross cut was made to a depth penetrating the polyurethane layer from the printing surface. Nichiban adhesive tape "Cellotape" was pressed against the printed surface with a finger and immediately peeled off. The state of peeling of the polyurethane layer was visually observed. Table 1 shows the results. "X" when polyurethane layer is attached to the adhesive tape
When the polyurethane layer did not adhere to the tape, the evaluation was "O".

Abrasion Resistance of Polyurethane Layer The solvent-resistant flexible relief printing plate was immersed in isophorone for 24 hours, taken out and allowed to stand for 4 hours. Thereafter, the printing surface was pressed with hand pressure (1300) using a commercially available plastic eraser.
g-1800 g). The abrasion state of the printing surface was visually observed. Table 1 shows the results. When the polyurethane layer was dropped, the evaluation was "x", and when the polyurethane layer remained, the evaluation was "o".

Printability of Solvent-Resistant Flexible Letterpress A solvent-resistant flexible letterpress was attached to a plate cylinder of a printing machine equipped with a 300-line anilox roll, and 20,000 copies were printed using a solvent type paint. Thereafter, the state of the surface of the plate was visually observed and evaluated. Table 1 shows the results. When a part of the plate was missing, it was marked "x", and when there was no missing, it was marked "o".

Example 2 Using 10 g of the acrylic polyol of Example 1, 56 g of a reaction product of 1 mol of trimethylolpropane and 3 mol of HMDI ("Coronate HL" manufactured by Nippon Polyurethane Co.) (equivalent ratio of hydroxyl group to isocyanate group) A solvent-resistant flexible relief printing plate was obtained and evaluated in the same manner as in Example 1 except for (1/2)). Table 1 shows the results.

Example 3 Using 10 g of the acrylic polyol of Example 1 and 280 g of a reaction product of 1 mol of trimethylolpropane and 3 mol of HMDI ("Coronate HL" manufactured by Nippon Polyurethane) (equivalent ratio of hydroxyl group to isocyanate group) 1/10)
Except for this, a solvent-resistant flexible relief printing plate was obtained and evaluated in the same manner as in Example 1. Table 1 shows the results.

Example 4 A solvent-resistant flexible relief printing plate was obtained and evaluated in the same manner as in Example 2, except that the surface protective composition contained 0.4% of dibutyltin dilaurate based on the solid content.
Table 1 shows the results.

Example 5 Instead of acrylic polyol, a number average molecular weight of 200
0, 10 g of an acrylic polyester polyol having a hydroxyl equivalent of 64 ("Nipporan 194" manufactured by Nippon Polyurethane)
Of a reaction product of 1 mol of trimethylolpropane and 3 mol of HMDI (“Coronate H” manufactured by Nippon Polyurethane Co., Ltd.)
L ") (solvent-resistant flexible relief printing plate) was evaluated and evaluated in the same manner as in Example 1 except that 150 g (equivalent ratio of hydroxyl group to isocyanate group) was used. Table 1 shows the results.

Example 6 10 g of the acrylic polyol of Example 1 was used, and 140 g of a trimer of HMDI ("Coronate HX" manufactured by Nippon Polyurethane Co., Ltd.) was used instead of the reaction product of 1 mol of trimethylolpropane and 3 mol of HMDI ( A solvent-resistant flexible relief printing plate was obtained and evaluated in the same manner as in Example 1 except that the equivalent ratio of the hydroxyl group to the isocyanate group was 1/8). Table 1 shows the results.

Comparative Example 1 A photosensitive resin plate material composed of N, N-diethylaminopropylmethacrylamide / lauryl methacrylate / 2-ethyleneanthraquinone used as a conventional flexible relief plate in each of the above examples (“Flexid B” manufactured by Nippon Paint Co., Ltd.) −067 ”), a print pattern was formed, and evaluated in the same manner as in Example 1. Table 1 shows the results.

[0093]

[Table 1] Example Coating properties Bending resistance Solvent resistance Adhesion Abrasion resistance Printability Weight Thickness Hardness 1 ○ ○ 15 10 10 ○ ○ ○ 2 ○ ○ 7 5 4 ○ ○ ○ 3 ○ ○ 3 1 0 ○ ○ ○ 4 ○ ○ 1 1 0 ○ ○ ○ 5 ○ ○ 14 12 9 ○ ○ ○ 6 ○ ○ 10 8 7 ○ ○ ○ Comparison 1 − − 34 38 26 − × ×

[0094]

According to the present invention, there is provided a flexible relief printing plate which has excellent solvent resistance and can be printed or designed by using an ink or paint containing a polar solvent. The flexible relief printing plate is more flexible than the offset blanket cylinder used in gravure offset printing, and therefore has excellent adaptability to the shape of the printing medium. Therefore, by using the solvent-resistant flexible relief printing plate of the present invention, even for a substrate having irregularities,
High quality printing or decorative coating can be performed with solvent type ink or paint.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a transfer roll used in the present invention.

FIG. 2 is a diagram showing an internal structure of a transfer roll, in which a foam layer is provided between a flexible letterpress layer and a printing roll shaft (shaft).

FIG. 3 is a view showing the internal structure of a transfer roll, in which a support layer is further provided between a foam layer and a printing roll shaft (shaft).

FIG. 4 is a view showing the internal structure of a transfer roll, in which a plastic sheet layer is further provided between a flexible relief layer and a foam layer.

[Explanation of symbols]

100: transfer roll, 101, 201, 301, 401: flexible letterpress layer, 102, 202, 302, 402: print roll shaft, 203, 303, 403: foam layer, 304, 404: support layer, 405: plastic Sheet layer.

Claims (14)

[Claims] 1. A solvent-resistant flexible letterpress having a plate surface formed of polyurethane. 2. The solvent-resistant flexible relief printing plate according to claim 1, wherein the polyurethane is formed by mainly reacting an active hydrogen compound with a polyisocyanate. 3. The solvent-resistant flexible relief printing plate according to claim 1, wherein the active hydrogen compound is a polyol. 4. The method according to claim 1, wherein the polyol is an acrylic polyol,
4. The solvent-resistant flexible relief printing plate according to claim 3, which is a polyester polyol. 5. The solvent-resistant flexible relief printing plate according to claim 2, wherein the polyisocyanate is a polyisocyanate prepolymer, a polymer of diisocyanate, or a triisocyanate obtained by reacting a polyol with an excess of diisocyanate. 6. An equivalent ratio of a hydroxyl group of a polyol to an isocyanate group of a polyisocyanate is from 1 / 0.5 to 1/2.
The solvent-resistant flexible relief printing plate according to claim 3, which is 0. 7. A solvent-resistant flexible relief printing plate having a support plate material layer and a surface protective layer formed thereon, wherein the support plate material layer is a plate material made of an elastic material. Is a solvent-resistant flexible letterpress made of polyurethane. 8. The solvent resistance according to claim 7, wherein the elastic body is formed of a polymer of a polymerizable monomer, rubber, a foam of rubber, or a reaction product of a rubber component and a polymerizable monomer. Flexible letterpress. 9. The solvent-resistant flexible relief printing plate according to claim 7, wherein the elastic body is a rubber having a surface hardness of JIS C30 ° to A80 °. 10. A step of applying a surface protective composition containing a polyisocyanate and an active hydrogen compound as a main component to a plate surface of an elastic plate material; and curing the applied surface protective composition to form a polyurethane. Forming a surface protective layer. 11. A surface protective composition for a flexible relief printing plate containing a polyisocyanate and an active hydrogen compound as main components. 12. A printing or printing method comprising: applying an ink or a paint to a printing surface of a solvent-resistant flexible letterpress having a relief printing surface made of polyurethane; and transferring the applied ink or coating to an article. Design painting method. 13. The method according to claim 12, wherein the ink or paint is a solvent-based ink or paint containing a polar solvent. 14. The method of claim 12, wherein the article is a pre-coated or uncoated metal material.