JP3144870B2 - Photosensitive elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photosensitive elastomer composition suitable for flexographic printing plates. More specifically, in a thermoplastic block copolymer comprising a monovinyl-substituted aromatic hydrocarbon polymer block and a conjugated diene polymer block, the content (A) of the monovinyl-substituted aromatic hydrocarbon and the vinyl group content of the conjugated diene The amount (V) is in a specific range, and (A) and (V) include the specific amount of the block copolymer component satisfying the specific relationship, the ethylenically unsaturated compound component and the photopolymerization initiator. A photosensitive elastomer composition comprising: The composition of the present invention exhibits excellent exposure sensitivity.For example, when used in the production of flexographic printing plates, not only can the plate making time be reduced to about half of the conventional one, but also small dots and lines can be reliably formed, and An excellent flexographic printing plate capable of printing a fine image without causing chipping of the plate during development can be obtained.

[0002]

2. Description of the Related Art Conventionally, a rubber plate for flexographic printing is manufactured by manufacturing a master plate by corroding a metal plate, manufacturing a master plate of plastic or the like from this, and then pouring rubber into the master plate and pressing it. It has been made. However, in this case, many steps are required, so that cost and time are taken too much, and
Since the obtained rubber plate itself has low accuracy, it has disadvantages such as necessitating back grinding when used. In order to solve this drawback, a method for producing a flexographic printing plate using a photosensitive elastomer composition has recently been proposed. According to this method, back grinding is not required, and it is possible to print even finer patterns than conventional rubber plates.

As such photosensitive elastomer compositions, for example, Japanese Patent Application Laid-Open No. 47-37521 (corresponding to British Patent No. 1366679) and Japanese Patent Application Laid-Open No.
No. 106501 (corresponding to U.S. Pat. No. 4,045,231), Japanese Patent Application Laid-Open No. 52-64301, Japanese Patent Application Laid-Open No. 53-127004 (U.S. Pat.
No. 30), Japanese Patent Application Laid-Open No. 54-110287 (corresponding to U.S. Pat. No. 4,177,074), and Japanese Patent Application Laid-Open No. 55-48744 (U.S. Pat. No. 4,266,005).
And Japanese Patent Application Laid-Open No. 58-62640 (corresponding to U.S. Pat. No. 4,431,723).

[0004] Of these, Japanese Patent Application Laid-Open No. 47-375.
No. 21, JP-A-53-127004, which uses a thermoplastic block copolymer as a binder, has a cold flow resistance in an uncured state and a rubber elasticity in a cured state. In practice, these solid-state photosensitive elastomer compositions for plate-making were exclusively used. In particular, those using fumarate or malate as an ethylenically unsaturated compound as described in Japanese Patent Application Laid-Open No. 53-127004 are not suitable for heating at the time of producing a photosensitive elastomer composition sheet or storage at a high temperature. The printing plate had excellent properties such as excellent thermal stability, flexibility of the resulting plate, and good mountability to a printing press cylinder. As a block copolymer in these conventional photosensitive elastomer compositions, a monovinyl-substituted aromatic hydrocarbon having a polymer block content of about 20 to 40% is used. The vinyl group content of the polymer block is small,
Generally, less than 15% was used.

[0005]

However, the photosensitive elastomer composition using the above-mentioned conventional block copolymer has the following problems. That is, first of all, these conventional photosensitive elastomer compositions have low sensitivity, and as a result, the time required for insolubilizing a developer by photocuring is too long, and in some cases, 20 minutes to 30 minutes.
Minutes or more image forming exposure time was required, resulting in a longer plate making time. In this case, if the exposure time is shortened, insolubilization of the photosensitive elastomer composition becomes insufficient, and a problem arises in that a relief portion corresponding to a small point or a line is hardly formed. In addition, when the intensity of the light beam is increased, there arises a problem that a relief corresponding to a small point or a line becomes thick or a white line is broken.

Second, in the conventional photosensitive elastomer composition, if the kind of the ethylenically unsaturated compound to be used is not selected, various mechanical properties after photo-curing are insufficient. In the case of development using a solvent and a brush, there is a problem that chips are generated particularly on reliefs corresponding to small dots and lines. In this case, when a compound that does not cause chipping during development is selected as the ethylenically unsaturated compound, there is a dilemma that the flexibility of the plate is insufficient. In particular, the use of fumarate or malate, which is known to greatly improve the flexibility of the plate and the thermal stability of the pre-photosensitive composition as described above, makes the problem of relief chipping more serious.

On the other hand, in recent years, as demand for flexographic printing plates has increased, printing of finer images has been demanded.
For this reason, there is an increasing demand for forming smaller dots and characters, and accordingly, in the process of washing with an organic solvent using a brush after exposure, the problem that the relief of such small dots and characters is lacking. Is becoming more important. In addition, there is a strong demand for shortening the plate making time, and therefore, it has been particularly desired to shorten the exposure time.

Under such circumstances, the present inventors can reliably form small dots and lines while shortening the plate making time, and can flexographically form the plate without causing chipping during development. Intensive studies have been made to develop a photosensitive elastomer composition for flexographic printing plates that can be used particularly advantageously in the production of printing plates. As a result, a thermoplastic block copolymer, a photosensitive elastomer composition comprising an ethylenically unsaturated compound component and a photopolymerization initiator, as a thermoplastic block copolymer

The polymer comprises at least one monovinyl-substituted aromatic hydrocarbon polymer block and at least one conjugated diene polymer block. The content (A) of the monovinyl-substituted aromatic hydrocarbon is 10 to 35% by weight, (A) a vinyl group content (V) of 20% to 50%;
And (V) use the specific amount of the block copolymer satisfying the following inequality: 40 ≦ (A) + (V) ≦ 70, the exposure sensitivity of the photosensitive elastomer composition is significantly improved,
It has been found that the above object can be achieved. The present invention has been made based on this finding.

[0010]

SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to not only reduce the time required for plate making to about half that of the prior art, but also to surely form small dots and lines, and to reduce the breakage of the plate during development. Printing plate and photoresist,
It is an object of the present invention to provide a novel photosensitive elastomer composition useful for producing a screen for screen printing, particularly for producing a flexographic printing plate. The above and other objects, features and advantages of the present invention will be apparent from the following detailed description and claims. That is, according to the present invention, the photosensitive elastomer composition is mainly composed of (1) at least one monovinyl-substituted aromatic hydrocarbon polymer block mainly composed of a monovinyl-substituted aromatic hydrocarbon and a conjugated diene. At least one
Consisting of two conjugated diene polymer blocks, wherein the content (A) of the monovinyl-substituted aromatic hydrocarbon is 10 to 35% by weight, and the vinyl group content (V) of the conjugated diene is 20% to 50%.
%, Wherein (A) and (V) satisfy the following inequality: 40 ≦ (A) + (V) ≦ 70 at least 50% by weight based on the elastomer composition of the thermoplastic block copolymer; 2) a photosensitive composition comprising 1 to 20% by weight of the ethylenically unsaturated compound component relative to the elastomer composition; and (3) 0.1 to 3% by weight of the photopolymerization initiator relative to the composition. An elastomer composition is provided.

Incidentally, the vinyl group content of the conjugated diene in the thermoplastic block copolymer used in the photosensitive elastomer composition of the present invention is, for example, in the case of a styrene-butadiene elastomer, the IR content of a 1% carbon disulfide solution. From the spectrum, the Hampton described in Anal. Chem., 21 , 923 (1949)
(Hampton) method. In the case of a styrene-isoprene elastomer, the peak areas A and B of the signal having a δ value of about 4.7 ppm derived from a vinyl bond and the signal of about 5.1 ppm derived from a 1,4 bond in the H ¹ -NMR spectrum were determined.

It is determined according to the following equation: vinyl% = A / (A + 2B) × 100. In the case of a styrene-butadiene-based block copolymer, the content of the monovinyl-substituted aromatic hydrocarbon is determined from the IR spectrum by the Hampton method. This method is described in the same literature as that mentioned for the vinyl bond content measurement method. In the case of a styrene-isoprene block copolymer, H ¹ -NM
The peak area C of the signal derived from hydrogen of the benzene ring having a δ value in the range of 6.3 to 7.3 from R and the area D of all the peaks can be obtained by the following equation. Styrene content (molar ratio) = Sm = 8/5 × C / D (104 × Sm) × 100 Styrene content (% by weight) = ─────────────────104 × Sm + 68 × (1-Sm) When the analysis for measuring the content is performed on a photosensitive elastomer composition, the analysis is performed after separating only the block copolymer from the composition.

In general, the image exposure when making a printing plate from the photosensitive elastomer composition is performed with the smallest highlight, the smallest point, the smallest line, etc. in the pattern to be obtained. This is performed until a portion requiring exposure is formed. Accordingly, the higher the exposure sensitivity of the photosensitive elastomer composition, the higher the intended highlight can be formed in a shorter time of image exposure, so that the photosensitive elastomer composition can be formed from the viewpoint of shortening the plate making time. Higher sensitivity has been desired. Also, by applying more image exposure, smaller dots and lines tend to be formed, but on the other hand, portions such as white lines are overexposed, so if overexposure is applied, filling (crushing) occurs. In the conventional photosensitive elastomer composition, it was difficult to perform image exposure until smaller spots were formed within a range in which the two could be balanced.

The development of the unexposed portion after image exposure is carried out exclusively by brushing using a solvent capable of dissolving the photosensitive elastomer composition. During the development process, the relief portion may be reduced in various mechanical properties due to swelling by the developing solution, and a phenomenon (chip) may occur in which the relief is partially removed while being rubbed by the brush. Such a phenomenon is more likely to occur for small dots and characters, and when printing is performed using a plate having a chip, a defective printed matter is not printed at that portion. Also, the smaller the highlight portion, the more easily chipping occurs during development, which limits the size of highlights that can be formed.
In the past, 3% of highlights were often the smallest highlights in the design, but recently, the formation of 1% highlights has been increasing, and in that case, the outline of white lines The fact that such 1% highlights cannot be formed due to the relief of the mask during development simply by applying more image exposure within the range where the filling does not occur is a problem in the conventional photosensitive composition especially before exposure. This is likely to occur when using fumarate or malate which attracts attention from the viewpoint of the thermal stability of the product and the flexibility of the produced flexographic printing plate, or when using methacrylate as an ethylenically unsaturated compound. Was.

According to the present invention, in a photosensitive elastomer comprising a thermoplastic block copolymer, an ethylenically unsaturated compound component and a photopolymerization initiator, a conjugated diene compound polymer block having a specific range of vinyl group content and a specific range By using a block copolymer having a monovinyl-substituted aromatic hydrocarbon content of (1), a photosensitive elastomer composition for flexographic printing plate making that has particularly high exposure sensitivity, chipping resistance during development, and rubber elasticity can be obtained. It is made possible.

In the photosensitive elastomer composition of the present invention, the block copolymer used in an amount of 50% by weight or more based on the elastomer composition comprises at least one block mainly composed of a monovinyl-substituted aromatic hydrocarbon; It preferably comprises two or more polymer blocks and at least one polymer block mainly composed of a conjugated diene.

In the composition of the present invention, a polymer block mainly composed of a monovinyl-substituted aromatic hydrocarbon is a monovinyl-substituted aromatic hydrocarbon in an amount exceeding 50% by weight, preferably 70% by weight or more. A copolymer block of a substituted aromatic hydrocarbon and a diene compound and / or a homopolymer block of a monovinyl-substituted aromatic hydrocarbon means a polymer block mainly composed of a conjugated diene. %,
A copolymer block of a diene compound and a monovinyl-substituted aromatic hydrocarbon containing preferably 70% by weight or more and / or
Or it means a diene compound homopolymer block.

The monovinyl-substituted aromatic hydrocarbons in the copolymer block may be distributed uniformly or tapered. The tapered distribution means that the content of the monovinyl-substituted aromatic hydrocarbon continuously changes in the longitudinal direction of the block. A plurality of uniformly distributed portions and / or tapered distributed portions may coexist in each block.

The thermoplastic block copolymer (1) used in the photosensitive elastomer composition of the present invention has a monovinyl-substituted aromatic hydrocarbon content (A) of 10 to 35% by weight, preferably 15 to 30% by weight. % By weight, the vinyl group content (V) of the diene compound chain is 20 to 50%, preferably 25 to 45%, more preferably 30 to 40%, and the relationship between (A) and (V) is 40 ≦ (A) + (V) ≦ 70, preferably 45 ≦ (A) + (V) ≦ 60.

The diene compound is a compound having a conjugated diene bond, for example, butadiene, isoprene, etc. Among them, butadiene having excellent ozone resistance and exhibiting the most excellent properties as a flexographic printing plate is most preferred. preferable. When the contents of (A) and (V) and the value of (A) + (V) do not satisfy the above ranges, the obtained photosensitive elastomer composition has sufficient sensitivity, chipping resistance during development, and flexographic printing. Rubber elasticity or the like suitable for a plate cannot be obtained.

Examples of the monovinyl-substituted aromatic hydrocarbon contained in the block copolymer used in the present invention include styrene, α-methylstyrene, ρ-methylstyrene, o-methylstyrene and the like. An example is styrene. These may be used alone or in combination of two or more. Further, the block copolymer used in the present invention may be a linear type or a radial type.

The present invention comprises at least one monovinyl-substituted aromatic hydrocarbon polymer block and at least one conjugated diene polymer block, and has a monovinyl-substituted aromatic hydrocarbon content (A) of 10 to 35. The weight percent conjugated diene has a vinyl group content (V) of 20 to 50%, and (A) and (V) have the following inequality: 40 ≦ (A) + (V) ≦ 70 Even if one type of polymer that satisfies this condition is used, even if one type is used, a plurality of polymers are used, and the average value obtained as a measured value for all of them satisfies this condition. No problem.

The thermoplastic block copolymer used in the present invention can be obtained, for example, by the method described in JP-A-63-27573 (corresponding to US Pat. No. 4,792,584). The content of the monovinyl-substituted aromatic hydrocarbon can be controlled within the range of the present invention by adjusting the charged amount. In addition, the adjustment of the vinyl bond content of the conjugated diene uses a polar compound as a vinylating agent in a polymerization method using an organolithium compound in a hydrocarbon solvent as an initiator, and controls the type, amount, and polymerization temperature of the polar compound. It can be done by doing.

As the hydrocarbon solvent, butane, pentane,
Aliphatic hydrocarbons such as hexane, isopentane, heptane, octane, and isooctane; cycloaliphatic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane; and aromatic hydrocarbons such as benzene and xylene. Can be used. As the organic lithium compound, an organic monolithium compound, an organic dilithium compound, an organic polylithium compound, or the like can be used, and specific examples include ethyllithium, propyllithium, butyllithium, hexamethylenedilithium, and the like. Further, polar compounds added to adjust the vinyl bond content include ethers such as tetrahydrofuran, diethylene glycol dimethyl ether and diethylene glycol dibutyl ether, amines such as triethylamine and tetramethylethylenediamine, thioethers, phosphines, and alkylbenzene sulfones. Examples include acid salts, alkoxides of potassium and sodium, and the like.

The ethylenically unsaturated compound component used in the present invention is not particularly limited.
Acrylates and methacrylates as described in JP-A-521 and JP-A-54-110287, N-substituted maleimides as described in JP-A-55-48744, and the like. And the following formula (I): (Wherein R ¹ and R ² are each independently an alkyl group, aryl group or aralkyl group having 2 to 30 carbon atoms) and include geometric isomers. it can. These ethylenically unsaturated compounds can be used alone or in combination. When these are used in combination, the compound represented by the above formula (I) is excellent in terms of rubber elasticity and flexibility, and from the viewpoint of obtaining the best plate as a flexographic printing plate completely formed with small points or characters. It is desirable to use at least one of the compounds in a proportion of at least 20% by weight, more preferably at least 50% by weight, of the ethylenically unsaturated compound component. In the above formula (I), R ¹ and R ² are preferably each independently an alkyl group having 6 to 12 carbon atoms.

The compounds represented by the above formula (I) are fumarate and malate. As described above, fumarate and malate are useful for giving the flexibility of the plate and for providing heat stability before exposure of the composition, but in a conventional photosensitive elastomer composition using fumarate or malate as an ethylenically unsaturated compound. Was particularly problematic with respect to chipping of the plate during development. However, surprisingly, when fumarate or malate is used as the ethylenically unsaturated compound in the present invention, the thermal stability of the pre-photosensitive composition is improved, and the rubber composition has excellent rubber elasticity and flexibility. The conventional defect of development, which is a drawback during use, is eliminated, and the most excellent flexographic printing plate in which even small points and characters are completely formed can be obtained.

Examples of such fumarate and malate include dibutyl fumarate, dioctyl fumarate, distearyl fumarate, butyl octyl fumarate, diphenyl fumarate, dibenzyl fumarate, dibenzyl fumarate and dibutyl maleate. Ester, maleic acid dioctyl ester, fumarate bis (3
-Phenylpropyl) ester and the like, but are not limited thereto. These may be used alone or in combination of two or more.

Further, fumarate has advantages such as higher reactivity and less toxicity than malate,
More preferred. The amount of the ethylenically unsaturated compound used in the present invention varies depending on the type and the properties of the flexographic printing plate to be obtained, such as hardness, but must be 1% by weight or more based on the composition. If the amount is less than this, the solvent cannot be sufficiently insolubilized by light irradiation, so that a satisfactory plate cannot be obtained. Conversely, if the addition amount is too large, the resulting plate will be hard and brittle, and the rubber elasticity will be low, so that it may not be possible to use it as a flexographic printing plate. Therefore, it is desirable that the amount added be 20% by weight or less based on the composition, and a more preferable addition amount is in the range of 5 to 15% by weight.

Examples of the photopolymerization initiator effective for the photosensitive elastomer composition of the present invention include benzoin and ethers thereof, for example, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, α-methylol benzoin methyl ether. , Α-methoxybenzoin methyl ether, 2,2-diethoxyphenylacetophenone and the like can be used. Such a photopolymerization initiator is added in an effective polymerization amount, that is, at least 0.001% by weight or more based on the composition. Generally, it is preferable to add in the range of 0.1 to 3% by weight.

The photosensitive elastomer composition of the present invention may contain 0.001 to 2% by weight of the composition based on a thermal polymerization inhibitor. Examples of such thermal polymerization inhibitors include 2,6-di-t-butyl-p-cresol, p-methoxyphenol, pentaerythritol tetrakis [3- (3 ′, 5′-di-t-butyl-4). '-Hydroxy) phenylpropionate] hydroquinone, t-butylcatechol, t-butylhydroxyanisole and the like can be mentioned as examples.

The photosensitive composition of the present invention may contain a plasticizer if desired. This plasticizer facilitates the removal of the unexposed portions of the photosensitive elastomer composition, improves the physical properties of the cured portions, and further aids in the production of the photosensitive elastomer composition, especially molding, and is targeted. It is added up to 40% by weight depending on the properties. Such materials include hydrocarbon oils such as naphthenic oil and paraffin oil, low molecular weight polystyrene (molecular weight of 3000 or less), α-methylstyrene-vinyltoluene copolymer,
Petroleum resin, pentaerythritol ester of hydrogenated rosin, polyterpene resin, polyester resin, polyethylene, poly (α-methylstyrene), polyacrylate, liquid 1,2- and 1,4-polybutadiene, liquid acrylonitrile butadiene copolymer, liquid Examples include styrene butadiene copolymer, stearic acid, polypentadiene, polyurethane, and ethylene propylene rubber.

Although the photosensitive elastomer composition of the present invention is solid at room temperature, it has tackiness depending on its composition, so that it can improve the contact with a transparent image alone superimposed thereon during plate making, and To enable reuse of the transparent image carrier, polyethylene, polypropylene,
A laminate layer of a thin film such as polyester, polystyrene or the like can be provided. The film is peeled off after exposure through the transparent image carrier overlaid thereon. A solvent-soluble thin flexible layer (see, for example, US Pat. No. 4,266,005) may be provided in place of the film for the same purpose. In this case, when the unexposed portion is eluted after the exposure through the transparent image carrier is completed, the layer is simultaneously removed by dissolution or the like.

The photosensitive elastomer composition of the present invention can be prepared by various methods. For example, the raw materials to be blended with a suitable solvent such as chloroform, carbon tetrachloride,
It is dissolved and mixed in a suitable solvent such as 1,1,1-trichloroethane, tetrachloroethylene, trichloroethylene, methyl ethyl ketone, methyl isobutyl ketone, toluene, and tetrahydrofuran, and cast into a mold to evaporate the solvent. It can be used as a plate as it is, and a layer having higher thickness accuracy can be obtained by subjecting the plate of the photosensitive elastomer composition to heat press treatment. Further, it can be kneaded with a kneader or a roll mill without using a solvent, and can be extruded, injected, pressed, calendered or the like to form a sheet having a desired thickness.

The protective film and the support film can be brought into close contact with the photosensitive layer by roll lamination after forming the sheet of the photosensitive elastomer composition. After lamination, the photosensitive layer can be further heated and pressed to obtain a photosensitive layer with higher thickness accuracy.
When a thin layer of a solvent-soluble material such as 1,2-polybutadiene, a soluble polyamide, a partially saponified polyvinyl acetate, or a cellulose ester is to be provided on the surface of the photosensitive layer, a suitable layer is used. The solution may be dissolved in a solvent and the solution may be directly coated on the surface of the photosensitive layer, or may be once coated on a film of polyester, polypropylene, or the like, and then laminated and transferred to the photosensitive layer together with the film.

The active light source used for insolubilizing the photosensitive elastomer composition of the present invention in a solvent includes a high-pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp, a xenon lamp, a zirconium lamp, and sunlight. After irradiating the photosensitive elastomer composition of the present invention with an actinic ray through a transparent image carrier to form an image, a developing solution (solvent) used for eluting the unexposed portion dissolves or dissolves the unexposed portion well. It is necessary that the image portion formed by dispersing and exposing is hardly affected.
Chlorinated organic solvents such as 1,1-trichloroethane and tetrachloroethylene, esters such as heptyl acetate and 3-methoxybutyl acetate, petroleum fractions, hydrocarbons such as toluene and the like, propanol and butanol and the like. A mixture obtained by adding and mixing the above alcohols can be given as an example.

The unexposed portion is eluted by spraying from a nozzle or brushing with a brush.
Brushing is common. The production of a flexographic printing plate using the photosensitive elastomer composition of the present invention includes, for example,
The following method can be used. Support film with or without adhesive layer, photosensitive elastomer composition sheet of desired thickness, polymer dissolvable or dispersible in solvent capable of dissolving or dispersing uncured (uninsolubilized) photosensitive composition A laminate is formed by laminating cover sheets with or without a layer (soluble flexible polymer layer), and the cover sheet is peeled from the laminate while leaving the soluble polymer layer. Next, back exposure is performed from the support side (step (a)), the portion of the photosensitive elastomer composition facing the support is cured over the entire surface, and further, an image carrier such as a negative film is brought into close contact with the soluble polymer layer [ Step (b)], performing relief exposure through the image carrier. At that time, the order of the steps (a) and (b) may be reversed. Next, an unexposed uncured portion of the composition layer after curing (insolubilization) is treated with the above-mentioned developer (for example, a chlorinated solvent such as tetrachloroethylene or 1,1,1-trichloroethane or a mixture thereof with an alcohol). ) To carry out development to obtain a relief printing plate. The obtained printing plate is washed, dried and post-exposed. The post-exposure may be performed in water, in which case the drying can be performed after the post-exposure.

As described above, the order of the back exposure and the relief exposure is not always necessary to perform the back exposure first, and the relief exposure may be performed first, or both may be performed simultaneously. Also, back exposure is not essential and can be eliminated. However, in general, it is preferable to perform back exposure from the viewpoint of obtaining a stable relief, and it is preferable to perform back exposure before the relief exposure in the order described above. When performing back exposure, the support film needs to be transparent to actinic rays. Although the photosensitive elastomer composition of the present invention exhibits excellent properties for flexographic printing plates, it can also be used as a photoresist or a screen for screen printing.

[0038]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. Example 1 Polystyrene-polybutadiene-polystyrene block copolymer (styrene content 25%, vinyl bond content 30
%, Melt index (MI) under G conditions according to ASTM D1238 = 3) 3 kg, liquid polybutadiene (number average molecular weight: 2000) 1 kg, dioctyl fumarate 500 g, polypropylene glycol diacrylate 150 g, 2,2-dimethoxy-2-phenyl 90 g of acetophenone and 9 g of 2,6-di-t-butyl-p-cresol were kneaded with a kneader to obtain a photosensitive elastomer composition.

The photosensitive elastomer composition was sandwiched between a polyester film having a urethane-based adhesive layer having a thickness of 100 μm and a polyester film having an ethylcellulose layer so as to be in contact with the adhesive layer and the ethylcellulose layer. Pressure molding was performed with a press using a spacer. The polyester film on the ethyl cellulose side of the obtained sheet was peeled off, and AF was removed.
A negative film was adhered to the exposed cellulose derivative layer on a P-1500 exposure machine (manufactured by Asahi Kasei, Japan), and image exposure of 4200 mj / cm ² was performed using an ultraviolet fluorescent lamp having a central wavelength of 370 nm. (Light intensity: 7 mW / cm ² ; exposure time: 10 minutes). Then, development was performed for 6 minutes with an AFP-1500 developing machine using tetrachloroethylene / butanol (3/1: volume ratio) as a developing solution.
After drying at 60 ° C. for 1 hour, post-exposure was performed at 1,000 mj / cm ² with the same light source as used for image exposure, and further, irradiation with a germicidal lamp was performed to remove stickiness on the plate surface, to obtain a flexographic printing plate.

In the printing plate obtained, 100 lines /
Highlights of up to 3% of inch were formed, and no chipping was observed in the relief portion. Flexographic printing was performed on a white polyethylene film using this plate, and good printed matter was obtained.

Comparative Example 1 A polystyrene-polybutadiene-polystyrene block copolymer having a styrene content of 25% and a vinyl bond content of 1
A photosensitive elastomer composition sheet was obtained in the same manner as in Example 1 except that a material having a melt index (MI) of 13% under G conditions according to ASTM D1238 was 13%. When a printing plate was prepared under the same conditions as in Example 1, the obtained plate had a highlight of 100 lines / inch 3% and formed only 20% or less in terms of the number of highlights of the corresponding size. In addition, a large number of chips which are considered to have occurred during development were observed in reliefs corresponding to characters and lines.

Examples 2 to 5 and Comparative Example 2 Preparation of a sheet of a photosensitive elastomer composition was carried out in the same manner as in Example 1 except that the block copolymer in the photosensitive elastomer composition of Example 1 was changed to various substances. The printing plate was made using this. Table 1 shows the results.

[Table 1]

Example 6 Polystyrene-polybutadiene-polystyrene block copolymer (styrene content 30%, vinyl bond content 30
%, Melt index (MI) under G condition according to ASTM D1238 = 12) 1500 g, polystyrene-
Polybutadiene-polystyrene block copolymer (styrene content 30%, vinyl bond content 13%, ASTM D
Melt index (MI) under G condition according to 1238
= 12) 1500 g, alkanediol (14 to 14 carbon atoms)
15) 150 g of diacrylate, 2,2-dimethoxy-
50 g of 2-phenylacetophenone, 2,6-di-t-
A photosensitive elastomer composition comprising 5 g of butyl-p-cresol was obtained by kneading using a kneader. A photosensitive elastomer composition sheet was prepared in the same manner as in Example 1 except that this photosensitive elastomer composition was used. Next, a flexographic printing plate was made in the same manner as in Example 1 and exposed to 4500 mj / cm ² to obtain 100 lines / inc.
Highlights of h3% could be formed, and no chip was observed at the relief of the obtained plate.

Example 7 Poly (α-methylstyrene) -polybutadiene-poly (α-methylstyrene) (α-methylstyrene content 30
%, A vinyl bond content of 30%, and a melt index (MI) under G condition according to ASTM D1238 = 10), and a photosensitive elastomer composition sheet was obtained in the same manner as in Example 1. When a flexographic printing plate was made in the same manner as in Example 1, the exposure was 4200 mj / cm ² and 100
Lines / inch 3% highlights could be formed, and no chipping was observed at the relief of the obtained plate.

Example 8 (polystyrene-polybutadiene) ₄ Si (styrene content 30%, vinyl bond content 25%, ASTM D123
Melt index (MI) under G condition by 8 = 8)
Using a radial type block copolymer, 500 g of dihexyl fumarate as an ethylenically unsaturated compound, N
Example 1 except that 150 g of laurylmaleimide were used
In the same manner as in the above, a photosensitive elastomer composition sheet was obtained.
When a flexographic printing plate was made in the same manner as in Example 1, the exposure was 4700 mj / cm ² and 100 lines /
A highlight of 3% inch could be formed, and no chipping was observed in the relief portion of the obtained plate.

Example 9 Polystyrene-polybutadiene-polystyrene block copolymer (styrene content 25%, vinyl bond content 30
%, Melt index (MI) under G condition according to ASTM D1238 = 10) 3.5 kg, liquid polybutadiene (number average molecular weight: 2000) 0.8 kg, dilauryl fumarate 0.6 kg, hexanediol diacrylate 0.1 K
g, 120 g of 2,2-dimethoxy-2-phenylacetophenone, 2,6-di-t-butyl-p-cresol 1
A sheet of the photosensitive elastomer composition was obtained from 5 g in the same manner as in Example 1. The polyester film on the ethyl cellulose side of the obtained sheet was peeled off, and AFP1500
A negative film was adhered to the exposed cellulose derivative layer on an exposure machine (manufactured by Asahi Kasei, Japan). First, a light source intensity of 4.8 mw / cm ² from an ultraviolet fluorescent lamp having a center wavelength at 370 nm from the support side was used. Back exposure was performed for 25 seconds with light, and then image exposure through a negative film was performed for 20 minutes (8400 mj / c) with light having a light source intensity of 7 mw / cm ² from an ultraviolet fluorescent lamp having a center wavelength at 370 nm.
m ² ). AF using the same developer as in Example 1
Develop with a P1500 developing machine for 6 minutes, dry at 60 ° C. for 1 hour, and then 1000
performs exposure after mj / cm ^2, it was germicidal lamp irradiation of 750 mJ / cm ² to further remove stickiness of the plate surface. In the obtained version, 133 lines / inch 1
% Of hylat, and no indentation was found in the relief. Flexographic printing was performed on a white polyethylene film using this plate, and a good printed matter with a wide gradation reproduction range was obtained.

Comparative Example 3 As a thermoplastic block copolymer, a polystyrene-polybutadiene-polystyrene block copolymer (styrene content 25%, vinyl bond content 14%, ASTM D123
Melt index (MI) = 1 under G condition according to 8
A sheet of the photosensitive elastomer composition was obtained in the same manner as in Example 9 except that 0) was used. The printing plate was made in the same manner as in Example 9.
With respect to highlights of 3 lines / inch 1%, only 20% or less of highlights of the corresponding size were formed. Next, plate making was performed by increasing the exposure amount of image exposure through a negative film to 14000 mj / cm ² , but 133 lines / inch
1% of the highlights formed only about half. At this time, the white line having a width of 400 μm was completely buried (crushed).

[0048]

The thermoplastic block copolymer comprising a monovinyl-substituted aromatic hydrocarbon polymer block and a conjugated diene polymer block has a monovinyl-substituted aromatic hydrocarbon content (A) and a conjugated diene vinyl group content. The amount (V) is in a specific range, and each of (A) and (V) satisfies a specific relationship, a specific amount of a block copolymer, an ethylenically unsaturated compound component and a photopolymerization initiator. Since the photosensitive elastomer composition of the present invention has excellent exposure sensitivity, when this composition is used, for example, in the production of a flexographic printing plate, not only the plate making time can be reduced to about half of the conventional one, but also An excellent flexographic printing plate capable of forming a fine image without forming a line or a line reliably and causing no chipping of the plate during development can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 7/038 G03F 7/00 502 G03F 7/027 G03F 7/031 G03F 7/033

Claims (8)

(57) [Claims] 1. A photosensitive elastomer composition comprising: (1) at least one monovinyl-substituted aromatic hydrocarbon polymer block mainly composed of a monovinyl-substituted aromatic hydrocarbon and at least mainly composed of a conjugated diene; 1
Consisting of two conjugated diene polymer blocks, and having a monovinyl-substituted aromatic hydrocarbon content (A) of 10 to 10.
35% by weight, heat in which the vinyl group content (V) of the conjugated diene is 20% to 50%, and (A) and (V) satisfy the following inequality: 40 ≦ (A) + (V) ≦ 70 (2) 1-20% by weight of the ethylenically unsaturated compound component relative to the elastomer composition; and (3) a photopolymerization initiator. A photosensitive elastomer composition comprising 0.1 to 3% by weight of the composition. 2. Component (2) is acrylates, methacrylates, maleimides, and the following formula (I): (Wherein R ¹ and R ² are each independently an alkyl group having 2 to 30 carbon atoms, an aryl group or an aralkyl group) and at least one selected from compounds including geometric isomers 2. The compound according to claim 1, which is an ethylenically unsaturated compound.
3. The photosensitive elastomer composition according to item 1. 3. The photosensitive elastomer composition according to claim 1, wherein the component (2) contains at least one compound (I) in an amount of 20% by weight or more based on the component (2). 4. The photosensitive elastomer composition according to claim 3, wherein the proportion of at least one compound (I) in the component (2) is 50% by weight or more. 5. The photosensitive elastomer composition according to claim ² , wherein R ¹ and R ^{2 in the} formula (I) each independently represent an alkyl group having 6 to 12 carbon atoms. 6. The photosensitive elastomer composition according to claim 1, wherein the monovinyl-substituted aromatic hydrocarbon polymer block in the thermoplastic block copolymer (1) is a polystyrene block. 7. The photosensitive elastomer composition according to claim 1, wherein the conjugated diene polymer block in the thermoplastic block copolymer (1) is a polybutadiene block. 8. The photosensitive elastomer composition according to claim 1, wherein the thermoplastic block copolymer (1) contains at least two monovinyl-substituted aromatic hydrocarbon polymer blocks.