JP2878300B2 - New letterpress printing plate - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel photosensitive resin letterpress. More specifically, the present invention relates to a relief printing plate having a multilayer structure in which a relief layer has a multilayer structure, which is excellent in solid ink inking property in relief printing and has good image reproducibility.

2. Description of the Related Art Conventionally, an adhesive layer or an antihalation layer is provided on a support such as plastic, metal, or paper, and one or two or more photosensitive resin layers are formed thereon. It is known to irradiate actinic rays through an image carrier to light cure selected portions of a photosensitive resin layer, remove unexposed portions and form a relief layer, and use it as a printing plate material. .

In recent years, with the increase in offset printing methods, in the field of letterpress printing, productivity has been improved, and plate materials with excellent print quality, for example, excellent solid resolving power, and good solidification of ink, with no smearing, are solid solid images. And a plate material having characteristics such as excellent gradation reproducibility has been required.

In general, in letterpress printing, the inking property and resolution of the ink vary greatly depending on the hardness of the printing plate material, and when a printing material having a high hardness is used, excellent resolving power can be obtained, but the inking property of the ink is inferior and vice versa. It is known that when a plate material having a low hardness is used, the ink is excellent in the inking property and a good and uniform solid image can be obtained, but it is difficult to obtain a high resolution with a large image thickness.

Therefore, in order to improve such a problem, for example, by changing the photopolymerization characteristics in the photosensitive resin layer, while increasing the resolution in the photosensitive resin letterpress,
Attempts have been made to sharpen the top of the relief to obtain a sharp printed image (JP-B-35-16614, JP-B-37-1306). However, in this letterpress material, in order to obtain a high solid printing quality, when the hardness of the plate material is high, a high printing pressure is required. As a result, even if a high resolution is achieved with the letterpress material, Due to the high printing pressure, the resolving power in printing is inevitably reduced due to the increase of marginal in halftone, and it is not possible to obtain excellent print quality such as offset printed matter.

Further, the base layer in the relief layer of the photosensitive resin letterpress is formed of a material softer than the top layer, and the cushioning effect of the base layer eliminates the printing pressure difference between the small image and the large image, which is a drawback of the letterpress printing method. (Japanese Patent Publication No. 61-50606). However, in this photosensitive resin relief printing plate material, when trying to obtain a high solid printing quality such as an offset printed material, when the entire plate material hardness is high, there is a cushioning property of a solid image portion, so that the top portion is formed. Higher printing pressure is required compared to those with a relief layer made of a single-layer photosensitive resin of the same hardness, and although the thickening can be reduced somewhat due to the cushion effect of the halftone portion, high solid printing quality comparable to offset printed matter And high resolution cannot be achieved.On the other hand, if the overall plate material hardness is soft, the solid printing quality can be satisfied, but if the printing press accuracy or the surface smoothness of the printing paper is poor, the fatness will be large. Cannot satisfy high resolution.

Problems to be Solved by the Invention The present invention overcomes the drawbacks of the conventional photosensitive resin letterpress, and achieves high solid printing quality even when using a letterpress printing press whose ordinary printing press accuracy is not so good. The object of the present invention is to provide a novel printing plate for letterpress that can realize both high resolution and high resolution.

Means for Solving the Problems Prior to developing a photosensitive resin letterpress having the above-mentioned excellent characteristics, the present inventors considered that the quality of printing obtained by each printing plate material was good for solid printing quality and high resolution. In particular, the solid printing quality cannot be expressed simply by a high reflection density, but is caused by minute white spots (hereinafter referred to as "snake") that are slightly observed in solids. It was found that the effect of quality deterioration due to the visually sensual rough feeling was greater. And this microscopic snake phenomenon, even if the plate type is different, is somewhat larger or smaller both in letterpress and offset plates, and it is understood that it is greatly involved in good and bad, and the ratio of this snake in solids is We found a method of quantitatively grasping the snake rate and judging the quality of solid printing quality.

The snake ratio is determined by using a dot analyzer (manufactured by Areadac AD-1000 Konica) to enlarge the solid printed portion of the printed material under reflected light, and to occupy the area occupied by the snake portion at a certain reflection density level (density slice level). And a value expressed as a percentage. The optimum value of the reflection density slice level in this measurement method changes depending on the printing medium, but the reflection density slice level is 0.5D in an example of newspaper printing paper.
The offset rate of offset paper is 2% for high quality solid printing
Hereafter, even if it is bad, it is 5% or less in commercially available products. On the other hand, the letterpress by the letterpress is good, about 5%, generally 5-10%, and the bad one is about 15%, and the solid printing quality of the letterpress paper is actually sufficient compared to the offset paper. Clearly not. The present inventors have considered that the reason why there are many slippages in solid printing on a letterpress paper surface is that it is impossible to give a sufficient printing pressure and ink amount to prevent a fine image from becoming thick.

On the other hand, for thickening of a fine image, a visual discrimination method using a test chart for quality control, which has been variously considered, such as a GATF chart, is generally used.However, the present inventors consider whether the resolution of printed matter is good or bad. As a method of quantitatively determining, a method of actually measuring the amount of fatness of a specific image was adopted. For example, in the case of newspaper printing, use a negative image having a line width of 60 μm, read the corresponding line width of the printing plate and the printing surface with a 100 times scale loupe or a universal projector, and determine the thickening amount from this difference. Can be. If the difference exceeds 80 μm, the sharpness of the entire surface of the paper is remarkably impaired, and in order to improve the resolution, it is required that the thickness is as small as 60 μm or less.

As described above, as a result of intensive studies to develop a relief printing plate made of a photosensitive resin capable of further improving solid printing quality and high resolution that determine the quality of printing quality, the result is that the relief layer has two or three relief layers. Each layer has the required thickness. In addition, the modulus of the top layer is less than 1/2 of the modulus of the base layer in the case of a two-layer structure, and the modulus of the middle layer or the base layer in the case of a three-layer structure. It has been found that a relief plate made of a photosensitive resin within a specific range of 1/2 or less of the above can be suitable for the purpose, and based on this finding, the present invention has been completed.

That is, the present invention provides a printing plate having a relief layer having a thickness of 8 mm or less formed of a cured photosensitive resin on a support, wherein the relief layer is composed of a top layer and a base layer,
The relief printing plate, wherein the top layer has a thickness of 2 μm or more and a modulus of 650 kg / cm ² or less, and the base layer has a thickness of 4 times or more and a modulus of 2 times or more of the top layer, In a printing plate having a relief layer having a thickness of 8 mm or less formed of a cured photosensitive resin on a support, the relief layer is composed of a top layer, an intermediate layer and a base layer, and the top layer has a thickness of 2 μm or more. Having a modulus of 650 kg / cm ² or less, and the sum of the thicknesses of the intermediate layer and the base layer is at least four times the thickness of the top layer, and the thickness of the intermediate layer is at least 0.1 mm and the modulus is at least twice the thickness of the top layer, The relief printing plate, wherein the modulus of the base layer is equal to or greater than that of the top layer, and the thickness formed of the cured photosensitive resin on the support
In a printing plate having a relief layer of 8 mm or less, the relief layer is composed of a top layer, an intermediate layer and a base layer, wherein the top layer has a thickness of 2 μm or more and a modulus of 650 kg / cm ² or less, and Wherein the thickness of the base layer is at least four times the sum of the thicknesses of the top layer and the intermediate layer, and the modulus of the base layer is at least twice the modulus of the top layer. It is intended to provide a relief printing plate.

 Hereinafter, the present invention will be described in detail.

The printing plate of the present invention requires that the relief portion be made of a cured photosensitive resin having a thickness of 8 mm or less, and the thickness is 8 mm.
If it is larger than this, not only the resolution in plate making is not sufficiently obtained, but also it is not economically appropriate.

The relief portion is composed of a top layer and a base layer having a specific thickness and modulus, respectively, or a top layer, an intermediate layer and a base layer, and the top layer has a thickness of 2 μm or more and 650 kg / cm ^2. Hereinafter, it is necessary to have a modulus of preferably 300 kg / cm ² . When the thickness is smaller than 2 μm or when the modulus is larger than 650 kg / cm ² , good solid printability and good printing reproducibility cannot provide good image reproducibility. When the relief portion has a two-layer structure of a top layer and a base layer, the thickness of the base layer is at least four times, preferably at least eight times the thickness of the top layer, and the modulus is at least twice the modulus of the top layer. It is necessary to be. If the thickness is less than 4 times or the modulus is less than 2 times, the entire relief layer becomes too soft, and the image becomes thicker, so that sharp printing cannot be obtained. On the other hand, when the relief portion has a three-layer structure of the top layer, the intermediate layer, and the base layer, the sum of the thicknesses of the intermediate layer and the base layer is 4 times the thickness of the top layer.
Times or more, preferably 8 times or more, the thickness of the intermediate layer is 0.1 mm or more, the modulus of which is twice or more the modulus of the top layer,
The modulus of the base layer is equal to or more than that of the top layer, preferably twice or more of the top layer, or the thickness of the base layer is four times or more, preferably eight times or more of the sum of the thicknesses of the top layer and the intermediate layer. The modulus of the base layer is at least twice the modulus of the top layer, and the thickness of the intermediate layer is 0.2 μm or more and 0.1 mm or less, preferably 2 μm or more and 0.1 mm or less. In this case, there is no particular limitation on the modulus of the intermediate layer. However, the modulus is preferably equal to or less than the modulus of the base layer. If the thickness of the intermediate layer and the base layer deviates from the above range, or their modulus does not satisfy the above conditions, the hardness of the entire relief layer is reduced, the image becomes thicker, and sharp printing cannot be obtained. .

In the present invention, the optionally inserted intermediate layer is for a bonding action between the top layer and the base layer,
Its thickness can be arbitrarily determined. Also, the top layer,
If the modulus of the base layer relative to the intermediate layer is relatively small, the entire relief can be buffered. Further, by changing the photosensitive characteristics and thickness of each of the top layer, the intermediate layer, and the base layer, a sharp relief shape can be obtained and the resolution can be enhanced.

The relief layer in the present invention is not limited to the one in which the convex portion is directly formed on the support, and the convex portion is formed on the photosensitive resin layer having a uniform thickness on the support. Such cases are also included.

The relief layer of the relief plate made of the photosensitive resin of the present invention is a liquid 2
It is preferable to prepare from a kind or three kinds of different photosensitive resin liquids, but it is also possible to use two or three kinds of solid photosensitive resin layers previously laminated on a support.

Examples of the liquid photosensitive resin include a photosensitive composition comprising an unsaturated polyester, an addition-polymerizable ethylenically unsaturated monomer, a photopolymerization initiator, and a thermal polymerization inhibitor.

The unsaturated polyester includes an alcohol component containing at least one polyol, at least one unsaturated polybasic acid or a derivative thereof (eg, acid anhydride, methyl or ethyl ester, acid halide), and if necessary, It is obtained by a polycondensation reaction with an acid component comprising a saturated polybasic acid added.

As unsaturated polybasic acids, maleic acid, fumaric acid,
Examples include citraconic acid, mesaconic acid, itaconic acid, glutaconic acid, muconic acid, aconitic acid, and the like.

Examples of the saturated polybasic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Can be mentioned.

Examples of the polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, polyethylene glycol (average molecular weight of 150 or more), and polypropylene glycol (average molecular weight of 192 or more). ), Polybutylene glycol (average molecular weight 162 or more), poly (oxyethyleneoxypropylene) glycol (average molecular weight 120 or more), glycerin, erythritol, pentaerythritol, hexid, trimethylolpropane, and the like.

As the addition-polymerizable ethylenically unsaturated monomer, acrylic acid, methacrylic acid, or an ester thereof, for example, methyl, ethyl, n-propyl, isopropyl, n-hexyl, n-octyl, n-dodecyl, cyclohexyl, tetrahydrofurfuryl, Acrylates and methacrylates of aryl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 4-hydroxybutyl, or mono- or diacrylates of ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, butylene glycol and Methacrylate, or trimethylolpropane triacrylate and methacrylate, pentaerythritol tetraacrylate and methacrylate And acrylamide, methacrylamide or derivatives thereof, for example, N-methylolacrylamide and methacrylamide, N-methoxyacrylamide and methacrylamide, N, N′-methylenebisacrylamide and methacrylamide, N, N′-hexamethylenebisacrylamide And methacrylamide, diacetone acrylamide and methacrylamide, and styrene, vinyltoluene, divinylbenzene,
Examples include diaryl phthalate, triaryl cyanurate, vinyl acetate, and the like.

Benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin-n
-Propyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, benzoin-sec-butyl ether,
α-methylbenzoin, α-ethylbenzoin, α-methylbenzoin methyl ether, α-phenylbenzoin, α-arylbenzoin, anthraquinone, chloroanthraquinone, methylanthraquinone, ethylanthraquinone, benzyl, diacetyl, acetophenone, benzophenone, ω-bromoacetophenone , 2-naphthalenesulfonium chloride, diphenyl disulfide,
Dyes such as eosin G (CI45380), thionine (C.
I.52025).

Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, catechol, tert-butylhydroquinone,
Benzoquinone, p-phenylenediamine, picric acid,
Phenothiazine and the like can be mentioned as examples.

Further, as another liquid photosensitive resin, a polymer obtained by reacting a prepolymer having at least two terminal isocyanate groups with an addition-polymerizable ethylenically unsaturated monomer having a hydroxyl group, an addition-polymerizable ethylenically unsaturated monomer, A photosensitive composition comprising a polymerization initiator and a thermal polymerization inhibitor can also be mentioned.

The prepolymer in this case is obtained by reacting a polyol compound having two or more terminal hydroxyl groups in the molecule with a polyisocyanate having at least two or more isocyanate groups. As the polyol compound, those having a relatively high molecular weight are preferable, and for example, polyether polyol, polyester polyol, polyalkylene polyol and the like are used. As the polyisocyanate, for example, tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate and the like are used. In this reaction, various ones can be obtained depending on the molar ratio of the polyol and the polyisocyanate, the reaction order, the reaction conditions, and the like. The prepolymer is reacted so as to have at least two terminal isocyanate groups.

Examples of the addition-polymerizable ethylenically unsaturated monomer having a hydroxyl group that reacts with the prepolymer include 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, and N
-Hydroxymethylacrylamide, polyethylene glycol monomethacrylate, allyl alcohol, hydroxystyrene and the like can be mentioned as examples.

Examples of the addition-polymerizable ethylenically unsaturated monomer, photopolymerization initiator, and thermal polymerization inhibitor used in this composition include those described above.

Further, other liquid photosensitive resins include a polyene containing at least two carbon-carbon unsaturated bonds per molecule, a polythiol containing two or more thiol groups per molecule, and a sensitizer such as benzophenone. (For example, JP-B-46-29525).

Changing the hardness of the liquid photosensitive resin after photocuring can be easily performed by a known method. For example, in the case of a liquid photosensitive resin comprising an unsaturated polyester, an addition-polymerizable ethylenically unsaturated monomer, a photopolymerization initiator and a thermal polymerization inhibitor, the unsaturated polybasic acid relative to the saturated polybasic acid in the unsaturated polyester The molar ratio of the addition-polymerizable ethylenically unsaturated monomer to the unsaturated polyester, and the molar ratio of the difunctional or polyfunctional monomer among the addition-polymerizable ethylenically unsaturated monomers The method or a combination of these methods is effective.

Further, a polymer obtained by reacting a prepolymer having at least two terminal isocyanate groups with an addition-polymerizable ethylenically unsaturated monomer having a hydroxyl group, an addition-polymerizable ethylenically unsaturated monomer, a photopolymerization initiator, and thermal polymerization In the case of a liquid photosensitive resin comprising an inhibitor, a method of changing the molecular weight of the prepolymer, a method of changing the molar ratio of the polymer and the addition-polymerizable ethylenically unsaturated monomer, Of these, a method of changing the molar ratio of the bifunctional or polyfunctional monomer, or a combination of these methods is effective.

Further, in the case of a liquid photosensitive resin comprising a polyene containing at least two carbon-carbon unsaturated bonds per molecule, a polythiol containing two or more thiol groups per molecule, and a sensitizer, Carbon per molecule in polyene
Method of changing the number of carbon unsaturated bonds, one in polythiol
A method of changing the number of thiol groups per molecule or a combination of these methods is effective.

In the present invention, the liquid photosensitive resin used for forming the top layer of the relief layer, the base layer, and the optional intermediate layer, if the modulus of each layer after forming the relief layer can satisfy the above conditions, It can be arbitrarily selected from the composition group.

Further, each liquid photosensitive resin used for forming the top layer, the optional intermediate layer and the base layer is selected from the same composition group, and the adhesiveness and image of each layer after plate making are determined. It is preferable from the viewpoint of cleaning and removing the unexposed resin with a common cleaning liquid after the formation exposure, but the present invention is not limited thereto. Here, the same composition group means a composition group in which the main components of the liquid photosensitive resin belong to the same chemical structural classification (for example, unsaturated polyester system, unsaturated polyurethane system, polyene system, etc.).

When the printing plate for letterpress of the present invention is formed from two or three solid photosensitive resin layers formed, it is particularly widely selected from various known materials for solid flexographic plates having rubber elasticity. Can be used. For example, Japanese Patent Publication No. 51-4337
JP-A-49-102405, JP-A-50-63091, and JP-A-50-63091, which comprise a thermoplastic elastomer composition disclosed in JP-A No. 4-104, an ethylenically unsaturated compound, and a photopolymerization initiator. No. 6034, JP-A-49-18721,
Japanese Patent Application Laid-Open No. 49-102406 discloses an example. Layers having different hardness can be formed according to the mixing ratio of each component of the photosensitive composition and other methods described above.

As the support used in the present invention, for example, a metal plate made of iron, stainless steel, copper, zinc, aluminum, etc., a rubber sheet made of natural rubber, synthetic rubber, or the like, or celluloid, cellulose acetate, polyethylene, polypropylene, polychlorinated Examples include plastic sheets or films of vinyl, polymethyl methacrylate, polystyrene, polycarbonate, polyethylene terephthalate, polyamide and the like. These supports usually have a thickness of 0.025 to 0.50 mm, and the surface thereof is generally provided with an antihalation layer and an adhesive layer.

Next, an example of a preferred method for producing the relief printing plate of the present invention will be described. First, a liquid photosensitive resin layer A and B or different liquid photosensitive resin layers A and B formed on a support.
After the seeds or three kinds of layers are sequentially provided so as to have a predetermined thickness, the photosensitive resin layer B or C is subjected to image exposure with actinic rays through a transparent image carrier from the side, and then the unexposed portion of the photosensitive resin is removed. After removal, a relief layer is formed on the support.

For the method of forming and laminating two or three kinds of liquid photosensitive resins and a support to a predetermined thickness in order to be subjected to exposure, for example, a hard photosensitive resin is brushed or rolled on a cover film closely arranged with a negative film. After the liquid photosensitive resin layer A is formed by previously spreading to a predetermined thickness using a doctor knife or the like, the liquid photosensitive resin layer B is formed as desired, and further the liquid photosensitive resin layer C is formed. It can be carried out by laminating a support. Alternatively, the photosensitive resin is spread to a predetermined thickness in advance using a brush, a roll, a doctor knife, or the like on the support to form a liquid photosensitive resin layer C, and then the liquid resin is subjected to the same operation using a hard photosensitive resin. The photosensitive resin layer B or B and A may be formed and laminated.

As the transparent image carrier used to form the relief image, not only a negative or positive film for photoengraving with a silver salt image, but also a plastic film and sheet that is substantially transparent to actinic rays, a glass sheet, An image is formed by masking the surface of cellophane paper, paper, or the like with a substance capable of preventing the transmission of actinic rays.

Examples of the actinic light source used in the exposure include a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a fluorescent lamp for ultraviolet rays, a carbon arc lamp, a xenon lamp, and sunlight.

In addition, image forming exposure when using a liquid photosensitive resin,
The liquid photosensitive resin layer A, the liquid photosensitive resin layer B or the resin layers A and B, the liquid photosensitive resin layer C, and the support are closely arranged in this order, and then the transparent photosensitive resin layer A side is used as the transparent resin. This is done with the light source through an image carrier. If the material of the support is substantially transparent to active light, irradiate the entire surface with active light from the support side to form a cured resin layer of a desired thickness on the support, and the height of the relief is optional. Can also be adjusted.

As described above, after irradiating the active image through the transparent image carrier, the unexposed or uncured resin is washed with various washing liquids, for example, water, alcohol, acetone, benzene, toluene, chloroethane, chloroethylene, and the like, an alkaline aqueous solution, For example, it is carried out by a method of washing and removing with an aqueous solution of sodium hydroxide, sodium carbonate, sodium phosphate, sodium tripolyphosphate, sodium borate, sodium silicate, or a surfactant aqueous solution. If necessary, a surfactant or the like can be added to the aqueous alkali solution.

The relief printing plate of the present invention has a relief layer having a multilayer structure including a top layer and a base layer, or a top layer, an intermediate layer and a base layer, and the top layer is softer than the base layer or the intermediate layer. What is formed is that, according to the relief printing plate, even when using a normal relief printing press whose printing press accuracy is not so good, a good solid image with excellent ink depositability and quality without thickening is obtained. And high image reproducibility can be obtained.

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

The modulus of the photocurable photosensitive resin is JIS K 7113
The stress-strain curve of the sample was prepared according to the following formula, and the gradient obtained by extending the initial linear portion was obtained by dividing the gradient by the cross-sectional area of the sample.

In this case, a 1 mm thick plate made of a photosensitive resin composition was prepared using a chemical lamp (FL20BL, manufactured by Toshiba).
It was prepared by curing by exposing for 5 minutes on both sides at an intensity of about 1.0 mW / cm ² .

Reference Example 1 Propylene glycol, diethylene glycol, adipic acid, fumaric acid, and isophthalic acid were each dissolved in a molar ratio of 0.1.
Compounded at a ratio of 25 / 0.75 / 0.50 / 0.25 / 0.25, 0.5 wt% of p-toluenesulfonic acid as an esterification catalyst and 0.2 wt% of hydroquinone as a thermal polymerization inhibitor were added, and the mixture was heated at 180 ° C. under a nitrogen atmosphere at normal pressure. The condensation reaction was performed for 3 hours. Then 2
The pressure was reduced to 0 mmHg, and the reaction was further performed at 220 ° C. for 3 hours.
28 unsaturated polyesters were obtained.

To 100 parts by weight of the unsaturated polyester, 35 parts by weight of 2-hydroxyethyl methacrylate, N-3-oxo-1,
A photosensitive resin composition was obtained by mixing 10 parts by weight of 1-dimethyl-butylacrylamide, 10 parts by weight of tetraethylene glycol dimethacrylate, 2 parts by weight of benzoin ethyl ether, and 0.1 part by weight of hydroquinone.

This resin composition is poured into a mold composed of two glass plates and a 1 mm thick spacer, and under an intensity of about 1.2 mW / cm ² using an ultraviolet fluorescent lamp (manufactured by Toshiba, FL-20BL). Irradiation was performed for 5 minutes from both sides. The modulus of the obtained photocurable resin plate was 650 kg / cm ² .

Reference Example 2 20 parts by weight of diethylene glycol dimethacrylate, 10 parts by weight of tetraethylene glycol dimethacrylate, and N-3 were added to 100 parts by weight of the unsaturated polyester obtained in Reference Example 1.
-Oxo-1,1-dimethyl-butylacrylamide 10 parts by weight, 2-hydroxyethyl methacrylate 20 parts by weight,
Benzoin ethyl ether 2.5 parts by weight, hydroquinone 0.1
The photosensitive resin composition was obtained by blending parts by weight.

The modulus of the photocurable resin plate obtained by curing this resin composition in the same manner as in Reference Example 1 was 2,800 kg / cm ² .

Reference Example 3 100 parts by weight of polycaprolactonediol (average molecular weight 510), polypropylene glycol (average molecular weight 950) 20
7 parts by weight, 50 parts by weight of tolylene diisocyanate, 0.5 part by weight of 2,6-di-t-butyl-p-cresol
After reacting at 0 ° C for 2 hours, 25 parts by weight of 2-hydroxyethyl methacrylate and 0.1 part by weight of hydroquinone were added, and further reacted at 80 ° C for 2 hours to obtain an unsaturated polyurethane.

35 parts by weight of 2-hydroxypropyl methacrylate, 20 parts by weight of diethylene glycol dimethacrylate, 1.5 parts by weight of benzoin ethyl ether, and 0.1 part by weight of hydroquinone were mixed with 100 parts by weight of the unsaturated polyurethane to obtain a photosensitive resin composition.

The modulus of the photocurable resin plate obtained by curing this resin composition in the same manner as in Reference Example 1 was 8,500 kg / cm ² .

Reference Example 4 100 parts by weight of ethylene oxide-propylene oxide block copolymer diol (containing 35% by weight of ethylene oxide units, molecular weight 2,000), 100 parts by weight of polyethylene adipate diol (molecular weight 2,000), tolylene diisocyanate
After mixing 21 parts by weight and 0.5 part by weight of dibutyltin laurate and reacting at 70 ° C. for 2 hours, 45 parts by weight of 2-hydroxypropyl methacrylate and 0.1 part by weight of hydroquinone were added.
A part by weight was added, and the mixture was further reacted at 70 ° C. for 2 hours to obtain an unsaturated polyurethane.

100 parts by weight of this unsaturated polyurethane, 10 parts by weight of 2-hydroxypropyl methacrylate, 10 parts by weight of diethylene glycol dimethacrylate, 10 parts by weight of lauryl methacrylate, 1.5 parts by weight of benzoin ethyl ether, and 0.1 part by weight of hydroquinone were mixed to form a photosensitive resin composition. I got something.

The modulus of the photocurable resin plate obtained by curing this resin composition in the same manner as in Reference Example 1 was 105 kg / cm ² .

Reference Example 5 100 parts by weight of ethylene oxide-propylene oxide block copolymer diol (containing 35% by weight of ethylene oxide unit, molecular weight 2,000), 100 parts by weight of polyethylene adipate diol (molecular weight 2,000), tolylene diisocyanate
After mixing 13 parts by weight and 0.5 parts by weight of dibutyltin laurate and reacting at 70 ° C. for 2 hours, 18 parts by weight of 2-hydroxypropyl methacrylate and 0.05 part of hydroquinone were added.
A part by weight was added, and the mixture was further reacted at 70 ° C. for 2 hours to obtain an unsaturated polyurethane.

To 100 parts by weight of the unsaturated polyurethane, 10 parts by weight of polypropylene glycol (molecular weight: 380) monomethacrylate, 12 parts by weight of lauryl methacrylate, 5 parts by weight of diethylene glycol dimethacrylate, 1.5 parts by weight of benzoin ethyl ether, and 0.1 part by weight of hydroquinone were added. A resin composition was obtained.

The modulus of the photocurable resin plate obtained by curing this resin composition in the same manner as in Reference Example 1 was 15 kg / cm ² .

Reference Example 6 To 100 parts by weight of the unsaturated polyurethane obtained in Reference Example 5, 13 parts by weight of lauryl methacrylate, 15 parts by weight of polypropylene glycol (molecular weight: 380) monomethacrylate, 4 parts by weight of diethylene glycol dimethacrylate, 1 part by weight of benzoin ethyl ether, hydroquinone 0.1 parts by weight was blended to obtain a photosensitive resin composition.

The modulus of the photocurable resin plate obtained by curing this resin composition in the same manner as in Reference Example 1 was 6.5 kg / cm ² .

Reference Example 7 15 parts by weight of lauryl methacrylate, 15 parts by weight of polypropylene glycol (molecular weight: 380) monomethacrylate, 3 parts by weight of tetraethylene glycol dimethacrylate, 1.5 parts by weight of benzoin ethyl ether were added to 100 parts by weight of the unsaturated polyurethane obtained in Reference Example 5. And hydroquinone in an amount of 0.1 part by weight to obtain a photosensitive resin composition.

The modulus of the photocurable resin plate obtained by curing this resin composition in the same manner as in Reference Example 1 was 3.0 kg / cm ² .

Reference Example 8 Water-soluble polyamide (Toray AQ nylon P-70) 100
Parts by weight, ethylene glycol 3 parts by weight, methanol 100
Parts by weight, diethylene glycol dimethacrylate 5 parts by weight, benzoin ethyl ether 1 part by weight, hydroquinone
0.2 part by weight was blended and stirred at room temperature for 1 hour to prepare a dope. This dope was coated on a polypropylene film having a thickness of about 22 μm to a thickness of about 0.04 mm using a doctor knife, and then dried at room temperature overnight to obtain a polypropylene film coated with a water-soluble polyamide film having a thickness of 25 μm. .

On the other hand, the above dope was dried in a vacuum dryer at 30 ° C. and 50 mmHg.
After heating for 4 hours at 110 ° C, the pressure was reduced to 0 kg / c.
Scanning alternately changing between m ² (gauge pressure) and 100 kg / cm ² (gauge pressure) is repeated 5 times to deaerate, then 120 kg / cm
^After pressurizing for 3 minutes at ² and cooling, a sheet having a thickness of 1 mm was prepared. A 9 μm-thick polyester film is adhered to both sides of the sheet, and the light-cured resin plate obtained by irradiating from both sides under the same light source as in Reference Example 5 for 5 minutes has a modulus of 280 kg /.
It was cm ^2.

Example 1 An image carrier was placed on a horizontally placed glass plate, and the image carrier was covered with a 9 μm-thick polyester film, and the photosensitive resin composition of Reference Example 5 was placed thereon using a doctor knife.
It was coated to a thickness of 0.03 mm.

Next, the photosensitive resin composition of Reference Example 3 was coated thereon with a doctor knife to a thickness of 0.5 mm, and an adhesive containing an antihalation agent was applied thereon. Covered with a mm thick polyester film support sheet.

Next, using a UV fluorescent lamp (FL-20BL, manufactured by Toshiba) from the support sheet side, exposure was performed at a UV intensity of 1.8 mW / cm ² for 25 seconds and then from the image carrier side for 5 minutes. An aqueous solution containing 1% by weight of sodium borate and 1% by weight of a surfactant at 40 ° C. was added to the photosensitive resin composition subjected to image formation exposure in this manner for 1.5k.
Spraying was performed for 1.5 minutes at an injection pressure of g / cm ² to wash and remove unexposed portions, followed by washing with water. Next, this photosensitive resin composition is submerged in a vat filled with water, and after performing post-exposure on the relief surface for 10 minutes using the light source, withdrawn from the water, and dried at 50 ° C. under warm air for 10 minutes. Was performed to obtain a relief plate made of a photosensitive resin having a thickness of 0.63 mm.

When this plate was used for printing on a letterpress rotary press, excellent printability was obtained even with a light printing pressure, and a sharp print with less thickening of the image was obtained. The solid image portion of this printed matter had a stickiness ratio of 2.0%, and the image having a line width of 60 μm had a thickening amount on the stamp face of 45 μm.

Comparative Example 1 Only the photosensitive resin composition of Reference Example 5 was used.
The same operation as in Example 1 was carried out except that the coating was performed to a thickness of 0.5 mm using a doctor knife to obtain a relief plate made of a photosensitive resin having the same thickness as in Example 1.

When printing was performed by a letterpress rotary press using this plate, the ink transferability was good, but the image was large in thickness and no sharp printed matter was obtained.

The printed image had a solid image portion having a run-out rate of 2.1%, but the thickening amount of the image was 120 μm. In the image obtained with a light printing pressure, the thickness of the same image was 50 μm, which was acceptable, but the snaking rate was as poor as 7%.

On the other hand, instead of the photosensitive resin composition of Reference Example 5, the photosensitive resin composition of Reference Example 3 was used, and a photosensitive resin relief plate having the same thickness as that of Example 1 was obtained in the same manner.

When this plate was used for printing on a letterpress rotary press, fine characters could be printed sharply, but in large characters and halftone dark areas, the ink tended to fade, and good prints could not be obtained.

In addition, the printing pressure was increased and the amount of ink was increased, and the solid quality of large characters became good.

Snake rate of these printed matter and fatness of the same image is 12%,
50 μm, 2%, 90 μm.

Example 2 In Example 1, except that the photosensitive resin composition of Reference Example 6 was first coated, and then the photosensitive resin composition of Reference Example 2 was coated thereon, and the coating thickness was changed. The same operation as in Example 1 was performed, and the thickness of the photosensitive resin composition of Reference Example 6 was 0.005 mm, 0.015 mm, 0.05 mm, 0.10 mm, and the thickness of the support was 0.1 mm different from 0.25 mm for comparison. A relief plate made of a photosensitive resin having a thickness of 0.60 mm including a body was prepared.

When these plates were used for printing on a letterpress rotary press, sharp prints were obtained with less thickening of the images and excellent ink transferability, except for those whose thickness was changed to 0.25 mm for comparison.

When the solid image portion of the printed matter of these plates satisfies the stickiness ratio of 2.0%, the amount of fattening from the printing plate of the same image as in Example 1 was as follows. The thickening amount refers to an amount that has changed (increased) with respect to the original plate image line width when a plate having a plate screen line width of 60 μm is printed.

Example 3 An image carrier was placed on a horizontal glass plate, and the
Cover with a thick polypropylene film, and apply the photosensitive resin composition of Reference Example 7 thereon using a doctor knife for 0.8 mm.
Then, the photosensitive resin composition of Reference Example 6 was coated thereon with a doctor knife to a thickness of 5.0 mm, and about 0.1 m
m polyester film.

Next, using the same light source as in Example 1, irradiation was performed first from the polyester film surface for 85 seconds, and then from the image carrier side for 10 minutes. A 2% by weight aqueous solution of a surfactant [Lypon F, manufactured by Lion Co., Ltd.] at 40 ° C. was sprayed onto the photosensitive resin composition exposed to image formation at an injection pressure of 1.5 kg / cm ² for 3 minutes. Unexposed portions were cleaned and removed. Next, this was immersed in a vat placed in water, irradiated with the light source from the relief surface for 15 minutes, and then dried under warm air at 50 ° C. for 10 minutes to obtain a relief plate made of a photosensitive resin. The thickness of this plate including the polyester film of the support was 5.95 mm.

When this plate was printed on corrugated cardboard using a flexographic printing machine, an upper case and a solid image exhibited excellent ink transferability, and a sharp print without crushing lower case letters was obtained.

The solid image portion of this printed material has a 1.5%
The thickness of the negative image with a line width of m from the printing plate is
It was 180 μm.

Comparative Example 2 Only the photosensitive resin composition of Reference Example 6 was used.
A photosensitive resin relief plate having a thickness of 5.95 mm was obtained in the same manner as in Example 3 except that the coating was performed to a thickness of about 6 mm using a doctor knife.

Using this plate, cardboard printing was performed by a flexographic printing machine in the same manner as in Example 3. However, if the ink transfer property was improved, small letters were broken, and no good printed matter was obtained.

Although the solid image portion of these printed materials had a good value of 2% in the percentage of snaking, the thickening amount of the line width of 300 μm, which is the same as in the example, was 3%.
It is as large as 00 μm, and the thickness is 180 to 2
The solid image portion of the sample having a size of 00 μm had an unacceptable rate of 5 to 6%.

Example 4 An image carrier was placed on a horizontal glass plate, and the
Cover with a polypropylene film having a thickness of 0.05 mm, and coat the photosensitive resin composition of Reference Example 4 thereon with a doctor knife to a thickness of 0.05 mm, and then apply the photosensitive resin composition of Reference Example 2 thereon to a thickness of 0.10 mm. Further, the photosensitive resin composition of Reference Example 1 was coated to a thickness of 0.7 mm using a doctor knife, and then covered with a 0.11 mm-thick polyester film to which an adhesive had been applied in advance.

This was used for 15 seconds from the polyester film surface using the same light source as in Example 1, and then the irradiated surface UV intensity was 11 mW / c.
m ² (meter; Oak Seisakusho Co., Model: UV-M01, filter: UV-35) water-cooled ultra high pressure mercury lamp having (manufactured by ORC Manufacturing, lamp Model: CHM-3000) was irradiated from the image carrier side 40 seconds . An aqueous solution containing 1% by weight of a surfactant (Lypon F, manufactured by Lion Corporation) and 1% by weight of sodium borate at 40 ° C. was added to the photosensitive resin composition after the image forming exposure at 1.5 kg / cm ² . Unexposed portions were washed by spraying at an injection pressure for 2 minutes. Then, immersed in a batter filled with water and irradiated from the relief surface for 10 minutes using the light source of Example 1,
It was taken out of the water and dried under warm air at 50 ° C for 10 minutes to obtain a relief plate made of a photosensitive resin having a thickness of 0.95 mm.

When this plate was used for printing on a letterpress rotary press, a good printed matter was obtained, in which the inking property of the ink was uniform and uniform, and the image reproduction was sharp.

Comparative Example 3 The photosensitive resin composition of Reference Example 2 was prepared in the same manner as in Example 4.
The photosensitive resin composition of Reference Example 1 was placed thereon to a thickness of 0.15 mm.
Each was coated to a thickness of 0.7 mm, and then covered with a 0.11 mm-thick polyester film to which an adhesive was previously applied, and the same operation as in Example 4 was carried out, except that the photosensitive resin composition layer of Reference Example 4 was not provided. A 0.95 mm thick photosensitive resin letterpress was obtained.

When this plate was used for printing with the same letterpress rotary press as in Example 4, the reproduction of the image was sharp, but the solid image was blurred, the inking property of the ink was poor, and the ink of the solid image was poor. When trying to improve the inking property, the sharpness of the image was lost, and a printed matter in which the inking property of a solid image and the sharpness of image reproduction were balanced was not obtained.

Example 5 An image carrier was placed on a horizontal glass plate, and the
After covering with a m-thick polypropylene film, the photosensitive resin composition of Reference Example 6 was further coated thereon using a doctor knife.
Coated to a thickness of 0.05 mm. Next, the photosensitive resin composition of Reference Example 1 was coated thereon with a doctor knife to a thickness of 0.35 mm.
Further, the photosensitive resin composition of Reference Example 6 was coated to a thickness of 0.1 mm, and then covered with a polyester sheet having a thickness of about 0.1 mm to which an adhesive containing an antihalation agent had been applied in advance.

Next, using the same light source as in Example 1, exposure was performed for 30 seconds from the polyester sheet side, and then for 4 minutes from the image carrier side, and then unexposed portions were washed out in the same manner as in Example 3.
Post-exposure and drying were performed to obtain a photosensitive resin relief plate A.

Further, the photosensitive resin composition of Reference Example 6 was coated with a doctor knife to a thickness of 0.05 mm, and then the photosensitive resin composition of Reference Example 1 was coated to a thickness of 0.15 mm by the same method.
All except that the photosensitive resin composition is coated with a doctor knife to a thickness of 0.30 mm in the same manner as described above, the letterpress B made of photosensitive resin.
I got

When printing was performed on these plates A and B with a letterpress rotary press, sharp prints with good ink transfer were obtained.

Comparative Example 4 Only the photosensitive resin composition of Reference Example 6 was used,
A photosensitive resin relief printing plate having the same thickness as in Example 5 was obtained by the same operation as in Example 5, except that the coating was performed to a thickness of 0.5 mm using a doctor knife. I printed using this version,
When the ink transfer property was improved, the image became thicker, and a sharp print was not obtained.

Example 6 On a horizontal glass plate on which an image carrier was placed, a polypropylene film coated with the water-soluble polyamide of Reference Example 8 at a thickness of 25 μm was placed so that the coating surface was on the top, and was placed in close contact with a rubber roller. did.

The photosensitive resin composition of Reference Example 3 was further coated thereon with a doctor knife to a thickness of about 0.4 mm, and was covered thereon with a polyester sheet of about 0.1 mm thickness coated with an adhesive containing an antihalation agent.

Next, using the same light source device as in Example 1, exposure was performed for 25 seconds from the polyester side and then for 5 minutes from the image carrier side. The photosensitive resin structure imaged as above
C., washed out with an aqueous solution containing 1% by weight of sodium borate and 1% by weight of a surfactant under an injection pressure of 1.0 kg / cm ² for 60 seconds, spray-washed, and dried at 50 ° C. for 10 minutes. Next, post-exposure was performed in air for 5 minutes using the same light source as in Example 1 to obtain a relief plate made of a photosensitive resin. The thickness of this plate is 0.51
mm.

When printing on this plate using a letterpress rotary press,
Printed matter showing good ink transferability, with uppercase letters and solids, without crushing lowercase letters, was obtained.

Comparative Example 5 The same operation as in Example 6 was performed, except that the polypropylene film having a thickness of 22 μm was used instead of the polypropylene film coated with the water-soluble polyamide of Reference Example 8 at a thickness of 25 μm, and having the same thickness as Example 6. A relief plate made of a photosensitive resin was obtained.

When this plate was used for printing on a letterpress rotary press, fine letters and solid images were blurred, and good printed matter was not obtained.

Example 7 An image carrier was placed on a horizontal glass plate, and the
Covered with a thick polypropylene film, and on top of this, Reference Example 5
The photosensitive resin composition of Reference Example 6 was coated to a thickness of 0.05 mm using a doctor knife, and then the photosensitive resin composition of Reference Example 6 was coated thereon to a thickness of 0.02 mm, and the photosensitive resin composition of Reference Example 4 was further placed thereon. After coating the composition to a thickness of 0.8 mm, it was covered with a polyester film having a thickness of about 0.1 mm to which an adhesive had been applied in advance.

Thereafter, using the same light source as in Example 1, exposure was performed for 20 seconds from the polyester side and for 2 minutes and 30 seconds from the image carrier side.
Subsequently, a 2% by weight aqueous solution of a surfactant [Lipon F, manufactured by Lion Corporation] at 40 ° C. was sprayed at a jet pressure of 1.5 kg / cm ² for 3 minutes to wash and remove unexposed portions. After immersing in a bat placed, irradiating from the relief surface using the light source for 10 minutes, and then drying under warm air at 50 ° C. for 10 minutes, a 1.00 mm thick photosensitive resin relief plate including a polyester film of the support was obtained. Was.

When this plate was used to print on a letterpress rotary press, characters,
Printed matter with a small balance of thin lines and a good solid inking property was obtained with good balance.

Continuation of front page (56) References JP-A-62-124559 (JP, A) JP-A-54-92402 (JP, A) JP-A-62-296142 (JP, A) JP-A-51-139404 (JP, A) JP-A-52-139508 (JP, A) JP-B-61-56506 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03F 7/00

Claims (3)

(57) [Claims] 1. A printing plate having a relief layer having a thickness of 8 mm or less formed of a cured photosensitive resin on a support, wherein the relief layer comprises a top layer and a base layer, wherein the top layer has a thickness of 2 μm or more. A printing plate for letterpress, wherein the printing plate has a thickness and a modulus of 650 kg / cm ² or less, and the base layer has a thickness of 4 times or more and a modulus of 2 times or more of the top layer. 2. A printing plate having a relief layer having a thickness of 8 mm or less formed of a cured photosensitive resin on a support, wherein the relief layer comprises a top layer, an intermediate layer and a base layer,
The top layer has a thickness of 2 μm or more and a modulus of 650 kg / cm ² or less, and the sum of the thicknesses of the intermediate layer and the base layer is four times or more the thickness of the top layer, and the thickness of the intermediate layer is 0.1 mm or more. A printing plate for letterpress wherein the modulus is at least twice that of the top layer and the modulus of the base layer is equal to or greater than that of the top layer. 3. A printing plate having a relief layer having a thickness of 8 mm or less formed of a cured photosensitive resin on a support, wherein the relief layer comprises a top layer, an intermediate layer and a base layer,
The top layer has a thickness of 2 μm or more and a modulus of 650 kg / cm ² or less, and the thickness of the intermediate layer is 0.2 μm or more and 0.1 mm or more.
Hereinafter, a relief printing plate, wherein the thickness of the base layer is at least four times the sum of the thicknesses of the top layer and the intermediate layer, and the modulus of the base layer is at least twice the modulus of the top layer.