JPH02970A - Novel letterpress printing plate - Google Patents

Abstract

PURPOSE:To realize both high-level solid printing quality and high resolution by forming a relief layer in multilayered structure consisting of a specific top part layer and a base part layer and making the top part layer softer than base part layer. CONSTITUTION:A relief part is made of a photosensitive resin cured body of <=8mm in thickness and consists of the top part layer and base part layer which have specific thicknesses and moduli respectively. The top part layer is >=2mum thick and has a <=650kg/cm<2>, preferably, <=300kg/cm<2> modulus, the thickness of the base part layer is >=4, preferably, >=8 times as large as that of the top part layer, and the modulus is more than twice that of the top part layer. Consequently, even when a normal letterpress printer whose printing accuracy is not so good is used, a solid image of excellent quality which has superior ink thickness and is free from line thickening is obtained and high image reproducibility is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel letterpress plate made of photosensitive resin. More specifically, the present invention relates to a letterpress printing plate having a relief layer having a multilayer structure, which has excellent ink receptivity for solid images in letterpress printing, and good image reproducibility.

Conventional technology Conventionally, an adhesive layer or an antihalation layer is provided on a support such as plastic, metal, or paper, and one or two types of
A photosensitive resin layer of more than 100% is formed, and is irradiated with actinic rays through an image carrier such as a negative film to photocure selected portions of the photosensitive resin layer, and unexposed areas are removed to form a relief layer. It is known to form a material and use it as a printing plate material.

In recent years, with the increase in offset printing methods, productivity has improved in the letterpress printing field, as well as plate materials with excellent printing quality, such as excellent resolution, good ink adhesion, and uniform solid images with no snags. There is a growing demand for plate materials that have characteristics such as excellent gradation reproducibility as well as excellent gradation reproducibility.

In general, in letterpress printing, the ink adhesion and resolution vary greatly depending on the hardness of the plate material.If a plate material with high hardness is used, excellent resolution can be obtained, but the ink adhesion is poor, and vice versa. It is known that when a plate material with low hardness is used, ink adhesion is excellent and a good, homogeneous solid image can be obtained, but the image becomes thicker and it is difficult to obtain high resolution.

Therefore, in order to improve such problems, for example, by changing the photopolymerization characteristics within the photosensitive resin layer,
Attempts have been made to improve the resolution of photosensitive resin letterpress plates and to obtain sharp printed images by making the tops of the reliefs acute angles (Japanese Patent Publications No. 35-16614 and Japanese Patent Publication No. 37-1306).

However, in order to obtain a high level of solid printing quality with this letterpress material, if the plate material has high hardness, a high printing pressure is required, and as a result, even if high resolution is achieved with the letterpress material,
Due to the high printing pressure, the resolution in printing inevitably decreases due to an increase in the marginal in halftones, making it impossible to obtain excellent print quality such as offset prints.

In addition, the base layer in the relief layer of the photosensitive resin letterpress is formed of a softer material than the top layer, and the cushioning effect of the base layer eliminates the difference in printing pressure between small and large images, which is a drawback of the letterpress printing method. This has also been attempted (Japanese Patent Publication No. 56506/1983).

However, with this photosensitive resin letterpress material, when trying to obtain high solid printing quality such as offset prints, if the overall hardness of the plate material is high, the solid image area has cushioning properties, so the top part Higher printing pressure is required compared to those with a relief layer made of a single layer of photosensitive resin of the same hardness, and although the cushioning effect in the midtone areas can reduce the thickness somewhat, the high solid printing quality is comparable to that of offset printing. On the other hand, if the overall hardness of the plate material is soft, even if the solid printing quality is satisfactory, if the printing machine precision or the surface smoothness of the printing paper is poor, the thickness will be large. high resolution cannot be achieved.

Problems to be Solved by the Invention The present invention overcomes the drawbacks of conventional letterpress plates made of photosensitive resin, and achieves high solid printing quality even when using a letterpress printing machine whose accuracy is not so good. The purpose of this invention is to provide a new letterpress printing plate that can achieve both high resolution and high resolution.

Means for Solving the Problems Prior to developing a letterpress plate made of photosensitive resin having the above-mentioned excellent characteristics, the present inventors determined that the printing quality obtained by each plate material was determined by solid printing quality and high resolution. Focusing on the fact that it depends on both sexes, we found that solid printing quality in particular
It has been found that quality deterioration cannot be expressed simply by a high reflection density, and is caused by the visually sensual feeling of roughness caused by minute white spots (hereinafter referred to as "snake") that are slightly visible in the solid surface. Ta. Furthermore, it was found that this microscopic snake phenomenon can be seen to a greater or lesser extent in both letterpress and offset printing, regardless of the printing format, and it has been found that it has a large influence on the quality of the print. We have found a method to quantitatively understand the snub rate and judge whether solid printing quality is good or bad.

The snuke rate is calculated using a halftone dot analyzer (Arerdac AD-
1000 (manufactured by Konica), the solid printed portion of the printed matter was enlarged under reflected light, and the area occupied by the snaking portion at a certain reflection density level (density slice level) was determined, and the value is expressed as a percentage. The optimal value of the reflection density slice level in this measurement method changes depending on the printing substrate, but to give an example of newspaper printing, the reflection density slice level is 0.5D, and the snake rate of the offset paper is of good quality. It is less than 20% for solid printing, and less than 5% for commercially available products even if it is bad. On the other hand, the quality of letterpress paper is good at around 5%, -5~10% numerically, and poor at around 15%, and compared to offset paper, the solid printing quality of letterpress paper is actually lower. It is clear that this is not enough. The inventors of the present invention believed that the reason why there are many stains on the solid printing surface of the printing plate is that sufficient printing pressure and ink amount cannot be applied to prevent fine images from becoming thick.

On the other hand, regarding the thickening of fine images, a visual judgment method using variously considered quality control test charts such as GATF charts is generally used. As a method for quantitatively determining the amount of weight, we adopted a method of actually measuring the amount of thickening in a specific image. For example, in the case of newspaper printing, a negative image with a line width of 60 μm is used, the line widths of the corresponding printing plate and printing surface are read using a loupe with a 100x scale, a universal projector, etc., and the amount of thickening is determined from the difference. I can do it. If the difference exceeds 80 μm, the sharpness of the entire paper surface will be significantly impaired, and in order to improve the resolution, it is required that the amount of thickening be as small as possible to 60 μm or less.

As a result of intensive research to develop a photosensitive resin letterpress plate that can further improve solid print quality and high resolution, which determine the quality of printing, we have developed a relief plate with two or three relief layers. Consisting of a multilayer structure, each layer has the required thickness, and the modulus of the top layer during printing is less than 1/2 of the modulus of the base layer in the case of a two-layer structure, and the intermediate layer or base in the case of a three-layer structure. It has been discovered that a photosensitive resin letterpress plate having a specific range of 1/2 or less of the modulus of the layer is suitable for the purpose, and based on this knowledge, the present invention has been completed.

That is, the present invention provides a printing plate having a relief layer formed of a cured photosensitive resin on a support and having a thickness of 8 mm or less, wherein the relief layer is composed of a top layer and a base layer, and the top layer has a thickness of 2 μm or less. A letterpress printing plate having a thickness of 650 ky/cm" or more and a modulus of 650 ky/cm" or less, and a base layer having 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 of 8 mm or less in thickness formed of a cured resin, 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 and 650J21.
? / am” or less, and the sum of the thicknesses of the intermediate layer and the base layer is at least 4 times the thickness of the top layer, the thickness of the intermediate layer is O, 1 mm or more, and its modulus is at least twice that of the top layer, A letterpress printing plate characterized in that the modulus of the base layer is equal to or greater than that of the top layer, and a printing plate having a relief layer with 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, the top layer has a thickness of 2 μm or more and a modulus of 6501129/cr1′ or less, and the intermediate layer has a thickness of 0.2 μm or more, 0.1 m.
m or less, the thickness of the base layer is 4, which is the sum of the thickness of the top layer and the middle layer.
The modulus of the base layer is 2 times the modulus of the top layer.
The object of the present invention is to provide a letterpress printing plate characterized by being more than twice as large.

The present invention will be explained in detail below.

In the printing plate of the present invention, the relief portion must be made of a cured photosensitive resin with a thickness of 8 mm or less, and this thickness is 8+
If it is larger than Il+1, not only will it not be possible to obtain sufficient resolution in plate making, but it will also not be economically viable.

In addition, this relief part is composed of a top layer and a base layer, or a top layer, an intermediate layer, and a base layer, each having a specific thickness and modulus, and the top layer has a thickness of 2 μm or more and 650 kfi/cm. Below, preferably 30
It is necessary to have a modulus of 0 to 9/cm" or less. If this thickness is less than 2 μm or the modulus is greater than 650729/cm',
Good image reproducibility cannot be obtained due to good solid printing properties and small printing pressure. In addition, if this relief part has a two-layer structure of a top layer and a base layer, the thickness of the base layer is 4 times the thickness of the top layer.
It is necessary that the modulus is at least twice that of the top layer, preferably at least 8 times that of the top layer. If the thickness is less than 4 times or the modulus is less than 2 times, the entire leaf layer becomes too soft, resulting in a thick image, making it impossible to obtain sharp printing. On the other hand, when the relief part has a three-layer structure of a top layer, an intermediate layer, and a base layer, the sum of the thicknesses of the intermediate layer and the base layer is at least 4 times, preferably at least 8 times, the thickness of the intermediate layer. The thickness is Q, 1 mm or more 1, the modulus is at least twice the modulus of the top layer, the modulus of the base layer is equal to or more than the top layer, preferably at least twice the top layer, or the thickness of the base layer is 4 times or more, preferably 8 times or more the sum of the thickness of the top layer and the middle layer,
The modulus of the base layer is more than twice the modulus of the top layer,
The thickness of the intermediate layer is 0.2 μm or more and 0.1 ram or less, preferably 2 μm or more. In this case, the modulus of the intermediate layer is not particularly limited, but it 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 if their modulus does not meet the above conditions, the hardness of the entire relief layer will decrease, resulting in a thick image, and sharp printing will not be obtained. .

In the present invention, the optionally inserted intermediate layer acts as a bond between the top layer and the base layer, and its thickness can be determined arbitrarily. Further, if the modulus of the base layer is smaller than that of the top layer and the middle layer, the entire relief can have a buffering effect. Furthermore, by changing the photosensitive characteristics and thickness of the top layer, intermediate layer, and base layer, it is possible to obtain a sharp relief shape and improve resolution.

The relief layer in the present invention is not limited to one in which convex portions are directly formed on a support, but may be one in which a photosensitive resin layer of uniform thickness is provided on a support and then convex portions are formed on the support. This also includes such cases.

The relief layer of the photosensitive resin relief plate of the present invention is preferably made from two or three different liquid photosensitive resin liquids, but two or three types of solid photosensitive resin layers are supported in advance. A layered layer on the body may also be used.

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 contains an alcohol component containing at least one polyol, at least one unsaturated polybasic acid or its derivative (for example, an acid anhydride, methyl or ethyl ester, acid halide), and optionally It is obtained by a polycondensation reaction with an added acid component consisting of a saturated polybasic acid.

Examples of unsaturated polybasic acids include maleic acid, 7mer λ malic acid, citraconic acid, mesaconic acid, itaconic acid, glutaconic acid, muconic acid, and aconitic acid.

Saturated polybasic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid,
Examples include azelaic acid, sepacic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid.

Examples of polyols include ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1.
4-Butanediol, diethylene glycol, dipropylene glycol, polyethylene glycol (average molecular weight 150 or more), polypropylene glycol (average molecular weight 192 or more), polybutylene glycol (average molecular weight 1
62 or more), poly(oxyethylene oxypropylene)
Examples include glycol (average molecular weight 120 or more), glycerin, erythritol, pentaerythritol, hexite, trimethylolpropane, and the like.

Addition-polymerizable ethylenically unsaturated septamers include acrylic acid, methacrylic acid, or esters thereof, such as methyl, ethyl, n-propyl, isopropyl, n-hexyl, n-octyl, n-dodecyl, cyclohexyl, and tetrahydrofuryl. Furyl, aryl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-chloro-
2-hydroxy, 4-hydroxybutyl acrylates and methacrylates, or ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol 1, butylene glycol mono- or diacrylates and methacrylates, or trimethylolpropane triacrylate and methacrylate, pentaerythritol tetraacrylate and methacrylate, etc., acrylamide, methacrylamide or derivatives thereof, such as N-methylolacrylamide and methacrylamide, N-methoxyacrylamide and methacrylamide, N,N-methylenebisacrylamide and methacrylamide, Examples include N,N-hexamethylene bisacrylamide and methacrylamide, diacetone acrylamide and methacrylamide, styrene, vinyltoluene, divinylbenzene, diaryl heptatalate, triaryl cyanurate, vinyl acetate and the like.

As a photopolymerization initiator, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin-n-
Probil ether benzoin isopropyl ether,
Benzoin-n-butyl ether, benzoin isobutyl ether, benzoin-5ec-butyl ether, a
-Methylbenzoin, σ-ethylbenzoin, α-methylbenzoin methyl ether, α-7enylbenzoin, σ-arylbenzoin, anthraquinone, chloroanthraquinone, methylanthraquinone, ethylanthraquinone, benzyl, diacetyl, acetophenone, benzophenone, ω-bromoacetophenone , 2-naphthalenesulfonium chloride, diphenyl disulfide, dyes such as Niosif G (C, 1,45380), thionine (c, +, 52025), and the like.

Examples of the thermal polymerization inhibitor include hydroquinone, p-methoxyphenol, catechol, tert-butylhydroquinone, benzoquinone, p-phenyl diamine, picric acid, and phenothiazine.

In addition, as other liquid photosensitive resins, a polymer obtained by reacting a prepolymer having at least two terminal incyanate groups with an addition-polymerizable ethylenically unsaturated heptadmer containing a hydroxyl group and an addition-polymerizable ethylenically unsaturated Also mentioned are photosensitive compositions comprising a 7-mer, a photopolymerization initiator, and a thermal polymerization inhibitor.

The prepolymer in this case is obtained by reacting a polyol compound having two or more terminal hydroxyl groups with a polyisocyanate having at least two or more isocyanate groups in the molecule.

The polyol compound preferably has a relatively high molecular weight, and for example, polyether polyols, polyester polyols, polyalkylene polyols, etc. are used. As the polyisocyanate, for example, toluylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, etc. are used. In this reaction, various products can be obtained depending on the molar ratio of polyol and polyisocyanate, reaction order, reaction conditions, etc., but the reaction is performed so that the prepolymer has at least two terminal isocyanate groups.

Examples of the addition-polymerizable ethylenically unsaturated monomer having a hydroxyl group to be reacted with this prepolymer include 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl methacrylate, N-
Examples include hydroxymethyl acrylamide, polyethylene glycol monomethacrylate, aryl alcohol, and hydroxystyrene.

Examples of the addition-polymerizable ethylenically unsaturated heptamer-1 photopolymerization initiator and thermal polymerization inhibitor used in this composition include those mentioned above.

Furthermore, other liquid photosensitive resins include polyenes containing at least two carbon-carbon unsaturated bonds per molecule, polythiols containing two or more thiol groups per molecule, and sensitizers such as benzophenone. A photosensitive composition comprising (for example, Reiko No. 46-29525) can be mentioned as an example.

The hardness of the liquid photosensitive resin after photocuring can be easily changed by a known method. For example, in the case of a liquid photosensitive resin composed of an unsaturated polyester, an addition-polymerizable ethylenically unsaturated heptamer, a photopolymerization initiator, and a thermal polymerization inhibitor, the unsaturated polybasic acid in the unsaturated polyester is Method of changing the molar ratio of basic acid, method of changing the molar ratio of addition polymerizable ethylenically unsaturated monomer to unsaturated polyester, difunctional or polyfunctional monomer among addition polymerizable ethylenically unsaturated monomers A method of changing the molar ratio of - 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 containing a hydroxyl group, an addition-polymerizable ethylenically unsaturated monomer, a photopolymerization initiator and In the case of a liquid photosensitive resin consisting of a thermal polymerization inhibitor, there are two methods: changing the molecular weight of the prepolymer, changing the molar ratio of the polymer and addition-polymerizable unsaturated monomer, addition-polymerizable ethylenically unsaturated monomer, etc. - A method of changing the molar ratio of difunctional or polyfunctional polymers, or a combination of these methods is effective.

Furthermore, 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, Effective methods include changing the number of carbon-carbon unsaturated bonds per molecule in the polyene, changing the number of thiol groups per molecule in the polythiol, or a combination of these methods.

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

Furthermore, it is important that the liquid photosensitive resins used for forming the top layer, the optional intermediate layer, and the base layer are selected from the same composition group to improve the adhesion and image quality of each layer after plate making. This is preferable from the viewpoint of cleaning and removing unexposed resin with a common cleaning liquid after formation exposure, but is not limited thereto. The same composition group as used herein refers to a composition group in which the main components of the liquid photosensitive resin belong to the same chemical structural class (for example, unsaturated polyester type, unsaturated polyurethane type, polyene type, etc.).

When the letterpress printing plate of the present invention is made from two or three solid photosensitive resin layers, a wide variety of known materials for solid flexo plates having rubber elasticity may be selected. Can be used. For example, the special public service 51-43
Thermoplastic elastomer composition disclosed in Japanese Patent Publication No. 374, consisting of an ethylenically unsaturated compound, and a photopolymerization initiator, and others disclosed in Japanese Patent Application Laid-open No. 1983-102405 and Japanese Patent Application Laid-open No. 1983-1989.
-63091, JP 50-6034, JP 49-18721, JP 49-10240
There is one in Publication No. 6. Layers having different hardnesses can be formed according to the blending ratio of each component of these photosensitive compositions and other methods described above.

Examples of the support used in the present invention include metal plates made of iron, stainless steel, copper, zinc, aluminum, etc.
Rubber sheets made of natural rubber, synthetic rubber, etc., or plastic sheets or films made of celluloid, cellulose acetate, polyethylene, polypropylene, polyvinyl chloride, polymethyl methacrylate, polystyrene, polycarbonate, polyethylene terephthalate, polyamide, etc. . These supports usually have a thickness of 0.025 to 0.50 mm, and their surfaces are usually provided with an antihalation layer and an adhesive layer.

Next, one of the preferred methods for producing the letterpress printing plate of the present invention will be described.
To explain an example, first, two or three types of layers consisting of different liquid photosensitive resins A and B or A, B, and C are sequentially provided on a support to a predetermined thickness, and then,
The photosensitive resin layer is imagewise exposed to actinic rays through the transparent image carrier from the B side or the C side, and then the photosensitive resin in the unexposed areas is removed to form a relief' layer on the support.

Regarding the method of molding and laminating two or three types of liquid photosensitive resins and a support to a predetermined thickness for exposure,
For example, a liquid photosensitive resin layer A is formed by spreading a hard photosensitive resin to a predetermined thickness using a brush, roll, doctor knife, etc. on a cover film that is closely aligned with a negative film, and then liquid photosensitive resin is applied as desired. While forming a photosensitive resin layer B and further forming a liquid photosensitive resin layer C,
This can be carried out by laminating supports. Alternatively, the liquid photosensitive resin layer C is formed by spreading the photosensitive resin on the support to a predetermined thickness using a brush, roll, doctor knife, etc., and then the liquid form is formed by the same operation using a hard photosensitive resin. It is also possible to form and laminate the photosensitive resin layer B or B and A.

Transparent image carriers used for forming relief images include not only negative or positive films for photolithography with silver salt images, but also plastic films and sheets that are substantially transparent to actinic light, glass sheets, There are materials in which images are formed by masking the surface of cellophane paper, paper, etc. with a substance that can prevent the transmission of actinic rays.

Examples of active light sources used in exposure include low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, ultraviolet fluorescent lamps, carbon arc lamps, xenon lamps, sunlight, and the like.

In addition, in the case of using a liquid photosensitive resin, the image forming exposure is performed after arranging the liquid photosensitive resin layer A1, the liquid photosensitive resin layer B, or A, B, and C and the support in this order, and then forming the liquid photosensitive resin layer. This is done using the light source through the transparent image carrier from the A side.

If the material of the support is substantially transparent to actinic light,
The height of the relief can also be arbitrarily adjusted by irradiating the entire surface of the support with actinic light to form a cured resin layer of a desired thickness on the support.

After irradiating active light through the transparent image carrier as described above, the unexposed or uncured resin can be cleaned using various cleaning solutions,
For example, water, alcohol, acetone, benzene, toluene, chloroethane, chloroethylene, etc., alkaline aqueous solutions such as sodium hydroxide, sodium carbonate, sodium phosphate, sodium tripolyphosphate, sodium borate, sodium silicate, etc., and surfactants. This is done by washing and removing with an aqueous solution of the agent. If necessary, a surfactant or the like may be added to the alkaline aqueous solution.

Effects of the Invention In the relief printing plate of the present invention, the relief layer has a multilayer structure consisting of 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. According to the letterpress, a solid image with excellent ink receptivity and no thickening can be obtained even when using a normal letterpress printing machine whose printing press accuracy is not so good. In addition, high image reproducibility can be obtained.

Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples.

The modulus of the photocurable photosensitive resin is JISK 7.
A stress-strain curve of the sample was prepared according to the method of the present invention, and the slope obtained by extending this initial straight line portion was determined by dividing the slope by the cross-sectional area of the sample.

The sample at this time was to expose a 1 mm thick plate made of a photosensitive resin composition to light from both the front and back sides using a chemical lamp (manufactured by Toshiba, FL 20BL) at an intensity of approximately 1-OmW/cm2 for 5 minutes. It was created by curing it.

Reference Example 1 Propylene glycol, diethylene glycol, adipic acid, hexamaric acid, and isophthalic acid were each used in a molar ratio of 0.
2510.7510.5010.2510.25 no 11
To this, 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 for 180' under nitrogen atmosphere and normal pressure.
The line combination reaction was carried out for 3 hours at o. Next, the pressure was reduced to 29 mmHg and the reaction was further carried out at 220°C for 3 hours to reduce the acid value to 2.
An unsaturated polyester No. 8 was obtained.

To 100 parts by weight of this unsaturated polyester, 35 parts by weight of 2-hydroxyethyl methacrylate, N-3-oxo-
10 parts by weight of 1,1-dimethyl-butylacrylamide,
10 parts by weight of tetraethylene glycol dimethacrylate, 2 parts by weight of benzoin ethyl ether, 0 parts by weight of hydroquinone
．． A photosensitive resin composition was obtained by blending 1 part by weight.

This resin composition was injected into a mold made of two glass plates and a 1 mm thick spacer, and using an ultraviolet fluorescent lamp (FL-20BL, manufactured by Toshiba), approximately 1.2 mW/c+++ was applied.
Irradiation was performed from both sides for 5 minutes each at an intensity of '.

The modulus of the obtained photocurable resin plate was 650 kg/cr.
It was a2.

Reference Example 2 To 100 parts by weight of the unsaturated polyester obtained in Reference Example 1, 20 parts by weight of diethylene glycol dimethacrylate, 10 parts by weight of tetraethylene glycol dimethacrylate, N
-3-oxo-1,1-dimethyl-butylacrylamide 10 parts by weight, 2-hydroxyethyl methacrylate 2
0 parts by weight, 2.5 parts by weight of benzoin ethyl ether, and 0.1 parts by weight of hydroquinone to obtain a photosensitive resin composition.

The modulus of a photocurable resin plate obtained by curing this resin composition in the same manner as in Reference Example 1 was 2.80072 g/
C was.

Reference example 3 Polycaprolactone diol (average molecular weight 51O) 10
0 parts by weight, polypropylene glycol (average molecular weight 95
0) 20 parts by weight, 50 parts by weight of tolylene diisocyanate, and 0.5 parts by weight of 2.6-di-t-butyl-p-cresol were mixed and reacted at 70°C for 2 hours.
25 parts by weight of hydroxyethyl methacrylate and 0.1 part by weight of hydroquinone were added, and the mixture was further reacted at 80°C for 2 hours to obtain an unsaturated polyurethane.

A photosensitive resin composition was obtained by blending 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 211 parts by weight of hydroquino into 100 parts by weight of this unsaturated polyushituff. Ta.

The modulus of a photocurable resin plate obtained by curing this resin composition in the same manner as in Reference Example 1 was 8.5007zg/C+
It was ++2.

Reference Example 4 Ethylene oxide-propyleoxide block copolymer diol (containing 35% by weight of ethylene oxide units, molecular weight 2,000) 100 parts by weight, polyethylene adipate diol (molecular weight 2.000) 100 parts by weight, tolylene diisocyanate 21 parts by weight, dibutyltin After mixing 0.5 parts by weight of laurate and reacting at 70°C for 2 hours, 45 parts by weight of 2-hydroxypropyl methacrylate and 0.1 parts by weight of hydroquinone were added, and the mixture was further reacted at 70°C for 2 hours. React to obtain unsaturated polyurethane;
.

To 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 blended. A photosensitive resin composition was obtained.

The modulus of a photocured resin plate obtained by curing this resin composition in the same manner as in Reference Example 1 was 105J29/cm''.

Reference Example 5 Ethylene oxide-propyleoxide block copolymer diol (containing 35% by weight of ethylene oxide units, molecular weight 2.000) 100 parts by weight, polyethylene adipate diol (molecular weight 2.000) 100 parts by weight, tolylene diisocyanate 13 parts by weight, dibutyltin After mixing 15 parts by weight of laurate and reacting at 70°C for 2 hours, 2-hydroxypropyl methacrylate 18
Part by weight and 0.05 part by weight of hydroquinone were added, and the mixture was further reacted at 70°C for 2 hours to obtain an unsaturated polyurethane.

10 parts by weight of polypropylene glycol (molecular weight 380) monomethacrylate was added to 100 parts by weight of this unsaturated polyurethane.
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 to obtain a photosensitive resin composition.

A photocurable resin plate obtained by curing this resin composition in the same manner as in Reference Example 1 had a modulus of 2 g/cm'' at 15°C.

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, and hydroquinone. 0.1
Parts by weight were blended to obtain a photosensitive resin composition.

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

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

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

Reference example 8 Water-soluble polyamide (Toshi AQ nylon P-70) 1
00 parts by weight, 3 parts by weight of ethylene brecol, 100 parts by weight of methanol, 5 parts by weight of diethylene glycol dimethacrylate, 1 part by weight of benzoin ethyl ether, and 2 parts by weight of hydroquinone were mixed and stirred at room temperature for 1 hour to prepare a dope. Use this dope with a doctor knife 2
A polypropylene film coated with a water-soluble polyamide film having a thickness of 25 μm was obtained by coating a 2 μm polypropylene film to a thickness of about 04 mm and drying it overnight at room temperature.

Meanwhile, the above dope was dried in a vacuum dryer at 30°0150mmH.
After drying under g for 1 hour and heating at 110℃ for 4 minutes,
After repeating the degassing operation at 0.100 kg/cm'' 4 to 5 times, it was pressed at 120 kg/cm'' for 3 minutes and then cooled to produce a sheet with a thickness of 1 mm. A 9 μm polyester film was attached to both sides of this sheet, and Reference Example 1
The modulus of a photocurable resin plate made by irradiating both sides under the same light source for 5 minutes each was 280,729/cra''.

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

Next, the photosensitive resin composition of Reference Example 3 was coated thereon to a thickness of 0.5++ m using a doctor knife, and an adhesive containing an antihalation agent was applied thereon in advance. Covered with a 0.1 mm thick polyester film support sheet.

Next, first, using an ultraviolet fluorescent lamp (manufactured by Toshiba, FL-20BL) from the support sheet side, an ultraviolet light intensity of 1.8 mW/c was applied.
m' for 25 seconds and then from the image carrier side for 5 minutes. The photosensitive resin composition imagewise exposed in this way is
An aqueous solution containing 1% by weight of sodium borate (C) and 1% by weight of a surfactant was sprayed at a spray pressure of 1.5 kg/cIN2 for 1.5 minutes to wash and remove the unexposed areas, followed by washing with water. Next, this photosensitive resin composition was submerged in a vat filled with water, and the relief surface was post-exposed for 10 minutes using the light source, and then pulled out of the water and dried under warm air at 50°C for 10 minutes. A photosensitive resin letterpress plate having a thickness of 63 mm was obtained.

When this plate was used to print on a rotary letterpress press, it showed excellent ink receptivity even with light printing pressure, and sharp printed matter with little thickening of the image was obtained.

The snag rate of the solid image area of this printed matter is 2.0%, 60μ
The amount of thickening on the stamp surface of the image having a line width of m was 45 μm.

Comparative Example 1 The same operation as in Example 1 was carried out using the photosensitive resin composition of Reference Example 5, except that a 0.5 mm coating was performed using a doctor knife, and a photosensitive resin letterpress plate having the same thickness as in Example 1 was prepared. I got it.

When this plate was used to print on a rotary letterpress press, the ink transfer properties were good, but the image was thick and sharp printed matter could not be obtained.

The snag rate of the solid image portion of this printed matter was 2.1%, but the amount of thickening of the image was 120 μm. The image obtained with a light printing pressure had an acceptable thickening of 50 μm, but the snag rate was 7%, which was poor.

On the other hand, in place of the photosensitive resin composition of Reference Example 5,
A photosensitive resin letterpress plate having the same thickness as in Example 1 was obtained in the same manner using the photosensitive resin composition.

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

In addition, by increasing the printing pressure and applying a large amount of ink, the solid quality of large letters was good, but the thickness of fine letters was noticeable and well-balanced printed matter could not be obtained.

The snake rate of these prints and the weight of the same image are 12%,
They were 50 μm, 2%, and 90 μm.

Example 2 In Example 1, the same operation as in Example 1 was performed 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. , the thickness of the photosensitive resin composition of Reference Example 6 is 0.005 mm,
0.015mm, 0.05mm, 0.10mm.

o, the thickness including the support is different from 25 mm o, eom
A letterpress plate made of photosensitive resin was prepared.

When printed on a letterpress rotary press using these plates, the result was 0.2
Except for the 5mm size, sharp prints with less thick images and excellent ink transfer properties were obtained.

The amount of thickening from the plate of the stamp surface of the same image as in Example 1 when the solid image portion snag rate of the printed matter of these plates satisfied 2.0% was as follows.

0.005mm 50μm0.015
+++m 40μm0.05mm
50μm0.10mm
60/Jm0.25 mm 90pm
Example 3 Good stamp surface Good stamp surface Good stamp surface Good stamp surface Poor stamp surface An image carrier is placed on a horizontal glass plate, and a 22 μm thick film is placed on it.
Cover with a thick polypropylene film, and apply the photosensitive resin composition of Reference Example 7 on top of this using a doctor knife.
The photosensitive resin composition of Reference Example 6 was coated to a thickness of 8 mm, and then the photosensitive resin composition of Reference Example 6 was coated to a thickness of 5.0 mm using a doctor knife. Covered with polyester film.

Next, using the same light source as in Example 1, first from the polyester film side for 85 seconds, then from the image carrier side for 10 seconds.
Irradiated for minutes. A 2% by weight aqueous solution of a surfactant (Lipon F, manufactured by Lion Corporation) was applied to the photosensitive resin composition exposed to image formation at 40°C for 3 minutes at a spray pressure of 1-5#9/c+x''. The unexposed areas were washed and removed.Next, this was submerged in a vat of water, and the relief surface was irradiated for 15 minutes using the light source, and then exposed to light for 50 minutes.
It was dried for 10 minutes under warm air at .degree. C. to obtain a photosensitive resin letterpress.

The thickness of this plate is 5.95m++ including the polyester film support! Met.

When this plate was printed on corrugated poles using a flexo printing machine, the uppercase letters and solid images showed excellent ink transfer properties, and the lowercase letters were also sharp without blurring and printed matter was obtained.

The snag rate in the solid image area of this printed matter is 1.5%, which is 30%.
The amount of thickening from the printing plate of the negative image having a line width of 0 μm was 180 μm.

Comparative Example 2 Using the photosensitive resin composition of Reference Example 6, 5.
A 95 mm photosensitive resin relief plate was obtained.

Using this plate, corrugated poles were printed using a flexo printing machine in the same manner as in Example 3, but when the ink transferability was improved, the lowercase letters became dull, so good printed matter could not be obtained.

These printed materials have a good snub rate in the solid image area: 2
%, but the thickness of the 300 μm line stripes, which is the same as in the example, is as large as 300 μm.
The snare rate of the solid image area of 80-200 μm is 5-5
It was poor at 6%.

Example 4 An image carrier was placed on a horizontal glass plate, covered with a 2 μm thick polypropylene film, and Reference Example 4 was placed on top of this.
The photosensitive resin composition of Reference Example 2 was coated with a thickness of 0.05 mm using a doctor knife, and then the photosensitive resin composition of Reference Example 2 was coated on top of the photosensitive resin composition of 0.10 mm, and the photosensitive resin composition of Reference Example 1 was further coated with a thickness of 0.05 mm. 7. After coating with a doctor knife, adhesive was applied on top of it in advance.
Covered with 1 mm polyester film.

Using the same light source as in Example 1, this product was exposed to the polyester film surface for 15 seconds, and then the irradiated surface was exposed to ultraviolet light at an intensity of 11 m.
W/cm” (Measuring instrument; Newly made by Oak Manufacturing, Model: UV
-Mo1.7 Ilter: UV-35) water-cooled ultra-high pressure mercury lamp (newly manufactured by Oak, lamp model: CH
M-3000) for 40 seconds from the image carrier side.

After this image-forming exposure, the photosensitive resin composition is
An aqueous solution containing 1% by weight of surfactant C (Lipon F, manufactured by Lion Corporation) and 1% by weight of sodium borate was prepared by 1.
The unexposed areas were cleaned by spraying at a spray pressure of 5 g/cm'' for 2 minutes.Then, the area was submerged in a vat filled with water, and the relief surface was irradiated for 10 minutes using the light source of Example 1. It was taken out from the water and dried under warm air at 50°C for 10 minutes to obtain a photosensitive resin letterpress plate with a thickness of 0.95 mm.

When this plate was used for printing on a rotary letterpress press, good printed matter was obtained with even and homogeneous ink receptivity and sharp image reproduction.

Comparative Example 3 The photosensitive resin composition of Reference Example 2 was
, 15 mm, and 0.7 mm of the photosensitive resin composition of Reference Example 1 was coated thereon, and then covered with an O, 11+++m polyester film coated with adhesive in advance, and the same operation as in Example 4 was carried out. A 0.95 mm photosensitive resin relief plate without the photosensitive resin composition layer of Reference Example 4 was obtained.

When this plate was used to print on the same letterpress rotary press as in Example 4, the image reproduction was sharp, but the solid image showed fading, the ink receptivity was poor, and the ink of the solid image was When trying to improve the ink receptivity, the sharpness of the image was lost, and it was not possible to obtain a printed matter with a good balance between the ink receptivity of the solid image and the sharpness of the image reproduction.

Example 5 An image carrier is placed on a horizontal glass plate, and a 22μ
After covering with a polypropylene film having a thickness of m, the photosensitive resin composition of Reference Example 6 was coated thereon in an amount of 0-0511111 using a doctor knife. Next, 0.35 m of the photosensitive resin composition of Reference Example 1 was coated on this with a doctor knife, and then 0.1 m of the photosensitive resin composition of Reference Example 6 was coated on this.
After coating, it was covered with a polyester sheet approximately 1 mm thick, which had previously been coated with an adhesive containing an antihalation agent.

Next, using the same light source as in Example 1, the polyester sheet side was exposed for 30 seconds, then the image carrier side was exposed for 4 minutes, and the unexposed areas 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 05 mm, then the photosensitive resin composition of Reference Example 1 was coated with a thickness of 0.15 mm in the same manner, and then the photosensitive resin composition of Reference Example 6 was coated with a thickness of 0.15 mm. A photosensitive resin letterpress B was obtained in the same manner as above except that the object was coated with a 30 mm doctor knife.

When these plates A and B were used for printing on a letterpress rotary press, sharp printed matter with good ink transfer properties was obtained in both cases.

Comparative Example 4 Using the photosensitive resin composition of Reference Example 6, a photosensitive resin letterpress plate having the same thickness as in Example 5 was obtained by the same operations as in Example 5, except that the sail was coated with a doctor knife. Printing was carried out using this plate, but when the ink transfer properties were improved, the image became noticeably thicker and sharp printed matter could not be obtained.

Example 6 A polypropylene film coated with the water-soluble polyamide of Reference Example 8 to a thickness of 25 μm was placed on a horizontal glass plate on which an image carrier was placed, with the coated side facing up, and placed in close contact using a rubber roller. did.

On top of that, the photosensitive resin composition of Reference Example 3 was coated with a doctor knife to a thickness of about 0.4 mm, and then covered with a polyester sheet of about 0.1 mm coated with an adhesive containing an antihalation agent.

Next, using the same light source device as in Example 1, the polyester side was exposed for 25 seconds and then the image carrier side was exposed for 5 minutes. The photosensitive resin composition image-formed as described above is
After washing with an aqueous solution containing 1% by weight of C1 sodium borate and 1% by weight of a surfactant under a spray pressure of LO kg/cm'' for 60 seconds, spray washing with water, and drying at 50°C for 10 minutes. Then, Example A photosensitive resin letterpress plate was obtained by post-exposure in air for 5 minutes using the same light source as in 1. The thickness of this plate was 0.51 mm.

When printing was carried out using this plate using a letterpress rotary press, printed matter was obtained that showed good ink transfer properties for uppercase letters and solids without crushing the lowercase letters.

Comparative Example 5 Using the photosensitive resin composition of Reference Example 3, the same operations as in Example 6 were carried out, except that a 22 μm thick polypropylene film not coated with water-soluble polyamide was coated with a 4 mm layer using a doctor knife. A letterpress plate made of photosensitive resin having the same thickness as in Example 6 was obtained.

When this plate was used to print on a letterpress rotary press, fading was observed in the uppercase letters and solid images, and good printed matter could not be obtained.

Example 7 An image carrier is placed on a horizontal glass plate, and a 22 μm
Cover with a thick polypropylene film, and apply Reference Example 5 on top of this.
0.05 photosensitive resin composition using a doctor knife.
The photosensitive resin composition of Reference Example 6 was coated to a thickness of mm, and then the photosensitive resin composition of Reference Example 6 was coated to a thickness of 0.02 mm, and then the photosensitive resin composition of Reference Example 4 was coated to a thickness of 0.8 mm+I+, and then an adhesive was applied in advance. It was covered with a previously applied polyester film of approximately 0.1 mm.

Thereafter, using the same light source as in Example 1, exposure was carried out for 20 seconds from the polyester side and for 2 minutes and 30 seconds from the image carrier side. Next, a 2% by weight aqueous solution of a surfactant (Lipon F, manufactured by Lion Corporation) was sprayed at 40°C for 3 minutes at a spray pressure of 1.5 kg/cm'' to wash and remove the unexposed areas. After submerging it in a vat filled with water and irradiating it from the relief surface with the above light source for 10 minutes, it was placed under warm air at 50°C for 1 hour.
After drying for 0 minutes, a 1.00 mm (7) photosensitive resin letterpress plate including a polyester film as a support was obtained.

When this plate was used for printing on a letterpress rotary press, a well-balanced printed matter was obtained, with less thick letters and fine lines, and good solid ink coverage.

Claims (1)

[Claims] 1. 8 m thick formed of a cured photosensitive resin on a support.
In a printing plate having a relief layer of 2 μm or less, the relief layer is composed of a top layer and a base layer, and the top layer has a relief layer of 2 μm or less.
A letterpress printing plate having a thickness of at least 650 kg/cm^2 and a modulus of at most 650 kg/cm^2, and a base layer having a thickness of at least 4 times and a modulus of at least 2 times that of the top layer. 2 8 m thick formed of photosensitive resin cured material on support
m or less, the relief layer is composed of 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 intermediate The sum of the thicknesses of the layer and the base layer is at least 4 times the thickness of the top layer, the thickness of the middle layer is 0.1 mm or more and its modulus is at least twice that of the top layer, and the modulus of the base layer is the same as or more than the top layer. A letterpress printing plate characterized by: 3 Thickness 8m formed of photosensitive resin cured material on support
m or less, the relief layer is composed of 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 intermediate The thickness of the layer is 0.2 μm or more and 0.1 mm or less, the thickness of the base layer is 4 times or more the sum of the thickness of the top layer and the middle layer, and the modulus of the base layer is 2 times or more the modulus of the top layer. A letterpress printing plate featuring the following.