JP2900075B2 - Photosensitive resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel photosensitive resin composition,
A photosensitive resin composition having good photosensitivity, processability, and developability with an aqueous alkali solution, providing a cured product excellent in elasticity at low temperatures, transparency, and water resistance, and suitable as a material for a photosensitive flexographic plate. There are things.

[Prior Art] Conventionally, as a plate material for flexographic printing, for example, a thermosetting resin is hot-pressed on an original plate obtained by etching a metal plate to form a matrix, and then rubber is poured into the matrix to be processed. And a photosensitive resin composition in which a synthetic rubber such as styrene-butadiene rubber or acrylonitrile-butadiene rubber is used as a main resin component, and a photopolymerizable monomer having a terminal ethylenic double bond is added thereto. Photosensitive resin plates obtained by plate-making products are known.

However, the former rubber plate requires a long time for plate making,
Further, it has disadvantages such as high manufacturing cost and poor image reproducibility of itself. On the other hand, the latter photosensitive resin plate containing a synthetic rubber as a main resin component is inferior in solvent resistance, abrasion resistance and durability, and is used as a developing solution during plate making, for example, halogenation of 1,1,1-trichloroethane or the like. The use of hydrocarbons has drawbacks such as worsening the working environment.

In order to improve such disadvantages, various photosensitive resin compositions for flexographic printing plates having water developability have recently been proposed (JP-A-54-110287, JP-A-61-22339). . However, these compositions are not practical due to the use of a special water / alcohol / alkali developer for the development process and the need for heating and a very slow development speed.

Furthermore, recently, conjugated diolefin hydrocarbons and α, β
-A photosensitive resin composition comprising a copolymer of an ethylenically unsaturated carboxylic acid and a monoolefinically unsaturated compound optionally used, and a photopolymerizable unsaturated monomer and a photosensitizer; It has been proposed (JP-B-59-29849). However, although this composition has various advantages over the conventional composition, it is not always satisfactory in terms of workability, transparency of the cured product and elasticity at low temperatures, and particularly in cold regions. The resulting printing plate has a problem that its hardness increases and it cannot be used as a flexographic printing plate.

[Problems to be Solved by the Invention] The present invention overcomes the drawbacks of the conventional photosensitive resin composition, is soluble in an alkaline aqueous solution, has excellent processability and photocurability, and has a low temperature. The object of the present invention is to provide a cured product excellent in elasticity, transparency and water resistance at the time, and to provide a photosensitive resin composition particularly suitable as a material for a flexographic printing plate.

[Means for Solving the Problems] The present inventors have conducted intensive studies to develop a photosensitive resin composition having the former preferable properties. As a result, the conjugated diolefin-based compound unit and an acrylate having an acidic functional group were obtained. A copolymer containing a unit and / or a methacrylate unit and optionally a monoolefin-based compound unit and a polyfunctional vinyl compound unit at a predetermined ratio, a photopolymerizable unsaturated monomer, It has been found that a composition comprising a sensitizer can achieve the object, and the present invention has been completed based on this finding.

That is, the present invention relates to (A) (A) 10 to 80 mol% of a conjugated diolefin compound unit, (B) 5 to 40 mol% of an acrylate unit and / or methacrylate unit having an acidic functional group, 0 to 80 mol% of unsaturated compound units and 0 to 5 mol% of (d) polyfunctional vinyl compound units
A copolymer comprising: (B) a photopolymerizable unsaturated monomer;
(C) A photosensitive resin composition containing a photosensitizer.

 Hereinafter, the present invention will be described in detail.

The copolymer of the component (A) in the composition of the present invention contains (A) a conjugated diolefin-based compound unit and (B) an acrylate unit and / or a methacrylate unit having an acidic functional group as essential units. In some cases, a copolymer containing (c) a monoolefin-based compound unit and (d) a polyfunctional vinyl compound unit is used.

Examples of the conjugated diolefin-based compound which forms the essential unit (a) in the copolymer include 1,3-butadiene, isoprene, chloroprene, and 1,3-pentadiene. Or 2
A combination of more than one species may be used. The conjugated diolefin-based compound unit needs to be contained in the copolymer at a ratio of 10 to 80 mol%. If this amount is less than 10 mol%, the rubber elasticity is inferior, and if it exceeds 80 mol%, the composition tends to have poor solid retention and processability.

As the acrylate or methacrylate having an acidic functional group which forms the essential unit (ii), a acrylate or methacrylate having a carboxyl group, a phosphoric acid group or a sulfonic acid group as an acidic functional group is preferable. Ethyl succinic acid, 2-acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl-2-
Hydroxyethyl phthalic acid, 2-acryloyloxyethyl hexahydrophthalic acid, 2-acryloyloxyethyl acid phosphate, 2-acryloyloxyethyl sulfonic acid, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl phthalic acid, 2-
Methacryloyloxyethyl hexahydrophthalic acid, 2
-Methacryloyloxyethyl acid phosphate,
Examples thereof include 2-methacryloyloxyethylsulfonic acid, and these may be used alone or in combination of two or more. The acrylate unit and / or methacrylate unit having the acidic functional group is contained in the copolymer.
It is necessary to contain 5 to 40 mol%, preferably 10 to 25 mol%. When the amount is less than 5 mol%, the composition has poor solubility in an aqueous alkali solution, and when it exceeds 40 mol%, the processability and the elasticity of the cured product tend to be reduced.

On the other hand, examples of the monoolefin-based compound which forms the unit (c) which may be introduced include ethyl acrylate, n-butyl acrylate, α-ethylhexyl acrylate, n-octyl acrylate, dodecyl acrylate, methoxyethyl acrylate, and ethoxyethyl. Acrylates or methacrylates such as acrylates, butoxyethyl acrylate, cyanoethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate or methacrylates corresponding to these acrylates, and even styrene;
Acrylonitrile, vinyl chloride, ethylidene norbornene, propenyl norbornene, dicyclopentadiene,
Cyclopentadiene and the like may be mentioned, and these may be used alone or in combination of two or more. The amount of the monoolefinically unsaturated compound unit optionally introduced into the copolymer is from 0 to 80 mol%, preferably from 20 to 60 mol%.
It is necessary to choose in the range of mol%. If this amount exceeds 80 mol%, the content of other units becomes relatively too low, and the object of the present invention cannot be sufficiently achieved.

Further, the optionally introduced polyfunctional vinyl compound forming the unit (d) is a compound containing two or more vinyl bonds in one molecule and having the same reactivity. Examples include, for example, ethylene glycol dimethacrylate, ethylene glycol diacrylate, trimethylolpropane trimethacrylate,
Polyhydric acrylates and methacrylic esters such as propylene glycol dimethacrylate and propylene glycol diacrylate, as well as divinylbenzene and trivinylbenzene, may be used alone or in combination of two or more. They may be used in combination. It is necessary to select the amount of the polyfunctional vinyl compound unit to be optionally introduced into the copolymer in the range of 0 to 5 mol%. If this amount exceeds 5 mol%, the strength of the cured product tends to decrease. When the unit is introduced at a ratio of 0.1 to 5 mol%, a composition giving a cured product having excellent rebound resilience can be obtained.

The copolymer of the component (A) is prepared by combining a conjugated diolefin-based compound, an acrylate and / or methacrylate having an acidic functional group, and optionally a monoolefin-based unsaturated compound and a polyfunctional vinyl compound with a predetermined amount. The monomer mixture contained in a proportion can be produced by radical polymerization usually using a radical initiator. For controlling the molecular weight, a molecular weight modifier is usually used, and the amount of the molecular weight modifier is preferably selected in the range of 0.1 to 5 parts by weight per 100 parts by weight of the total amount of all the monomers.
Further, the polymerization agent such as each monomer or radical initiator may be added in its entirety before the start of the reaction, or may be arbitrarily divided and added after the start of the reaction. The polymerization is usually performed using an inert gas such as nitrogen. The reaction is carried out in an atmosphere at a temperature in the range of 0 to 50 ° C, but operating conditions such as temperature and stirring can be arbitrarily changed during the reaction. As a polymerization system, any of a continuous system and a batch system can be used.

Examples of the radical initiator include organic peroxides such as benzoyl peroxide, cumene hydroperoxide, paramenthane hydroperoxide and lauroyl peroxide, diazo compounds such as azobisisobutyronitrile, inorganic compounds such as potassium persulfate, and organic compounds. And a redox catalyst comprising a combination of iron sulfate and the like. Examples of the molecular weight regulator include t-dodecyl mercaptan, dialkylxanthogen disulfide and the like.

In the composition of the present invention, examples of the photopolymerizable unsaturated monomer used as the component (B) include styrene and α-
Methylstyrene, m-methylstyrene, p-methylstyrene, aromatic vinyl compounds such as p-methoxystyrene, unsaturated nitrile compounds such as acrylonitrile and methacrylonitrile, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, Alkyl alcohol acrylates such as isobutyl acrylate and t-butyl acrylate or methacrylates corresponding thereto, hydroxyalkyl alcohol acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate or methacrylates corresponding thereto, methoxy Acrylates or methacrylates of alkoxyalkylene glycols such as ethylene glycol and methoxypropylene glycol; Monoesters of unsaturated polycarboxylic acids such as monoethyl phosphate, monoethyl fumarate, monoethyl itaconate, dimethyl maleate, diethyl maleate, dibutyl maleate, dioctyl maleate, diethyl fumarate, dibutyl fumarate, fumaric acid Dioctyl, dimethyl itaconate, diethyl itaconate,
Diesters such as dibutyl itaconate and dioctyl itaconate, acrylamide, methacrylamide, N, N '
Acrylamide or methacrylamides such as methylenebisacrylamide, N, N'-hexamethylenebisacrylamide, ethylene glycol diacrylate or dimethacrylate, diacrylate or dimethacrylate of polyalkylene glycol (2 to 23 alkylene glycol units), glycerin , Pentaerythritol,
Diacrylates, triacrylates, tetraacrylates or dimethacrylates, trimethacrylates, tetramethacrylates, oligoacrylates, 2-acryloyloxy of polyhydric alcohols such as trimethylolalkane and tetramethylolalkane (alkanes are methane, ethane and propane) Ethyl succinic acid, 2-
Acryloyloxyethyl phthalic acid, 2-acryloyloxyethyl-2-hydroxyethyl phthalic acid, 2-acryloyloxyethyl hexahydrophthalic acid, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl Examples include acrylates or methacrylates having an acidic functional group such as phthalic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, and 2-methacryloyloxyethyl acid phosphate.

These photopolymerizable unsaturated monomers may be used alone or in combination of two or more. The compounding amount is usually 5 parts by weight per 100 parts by weight of the copolymer (A). ~Four
00 parts by weight, preferably in the range of 10 to 300 parts by weight. If the amount is less than 5 parts by weight, curing is insufficient,
The mechanical properties of the cured product may be poor, and if it exceeds 400 parts by weight, the rubber elasticity and the solvent resistance of the cured product tend to decrease, which is not preferable.

Further, in the composition of the present invention, as the photosensitizer used as the component (C), those usually used as a photoreaction initiator, for example, α-diketones such as diacetyl and benzyl, benzoin, pivaloin and the like Examples include acyloin compounds, acyloin ethers such as benzoin methyl ether, benzoin ethyl ether and benzoin propyl ether, and polynuclear quinones such as anthraquinone and 1,4-naphthoquinone.

These photosensitizers may be used alone or in combination of two or more, and the amount added is usually (A)
It is selected in the range of 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the component copolymer. If the amount is less than 0.1 part by weight, sufficient curing cannot be obtained, and if the amount exceeds 10 parts by weight, all of the added photosensitizers are not involved in the reaction, which is uneconomical. However, the reaction rate tends to decrease, which is not preferable.

The composition of the present invention can optionally contain a storage stabilizer. Examples of the storage stabilizer include hydroxyquinone, p-methoxyphenol, pt-butylcatechol, 2,6-di-t-butyl-p-cresol, hydroxyaromatic compounds such as pyrogallol, benzoquinone,
Examples thereof include quinones such as p-toluquinone and p-xyloquinone, and amines such as phenyl-α-naphthylamine.

These storage stabilizers may be used alone or in combination of two or more, and the amount of the storage stabilizer is usually 0.01 to 2 parts by weight per 100 parts by weight of the copolymer of the component (A). Selected by range.

One of the features of the composition of the present invention is the developability in a dilute aqueous alkaline solution. Examples of the diluted alkaline aqueous solution used as the developer include a low-concentration aqueous solution of about 0.1 to 4.0% by weight such as sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia, and lithium carbonate. The composition can be developed not only with such a dilute aqueous alkaline solution but also with a mixed solvent of an aqueous alkaline solution and alcohol or Kent.

Since the photosensitive resin composition of the present invention has a high photosensitivity, the exposure time can be short, and the solubility in a dilute alkaline aqueous solution is extremely high, so that it can be developed in about 1 to 2 minutes, and after drying. , Has the feature that it can be printed immediately, by using this composition,
Compared with the conventional plate making of a rubber plate for flexographic printing, the plate making process is simple and the working time can be greatly reduced.

Furthermore, the flexographic printing plate obtained by using the composition of the present invention can, of course, be printed with a solvent-type flexographic ink, but because of its good water resistance, it can be used instead of the solvent-type flexographic ink in terms of air pollution. Printing with the aqueous flexo ink being used is possible.

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

 In addition, the physical properties of the resin composition were determined as follows.

(1) Water resistance The resin layer was punched out into a disk having a diameter of 3.0 cm by exposing to the front and back for 5 minutes without a negative film, and immersed in a solution having a weight ratio of ethanol / water = 1/9 for 12 hours. % By weight).

(2) Alkaline water-soluble About 1.0 g of the resin composition was precisely weighed, and 100 ml of a 1% by weight aqueous solution of sodium hydroxide was added thereto, followed by ultrasonic irradiation with an ultrasonic cleaner for 30 minutes. Then it is filtered through a 150 mesh whole screen,
The residue remaining on the entire screen was vacuum-dried at 80 ° C. for 20 hours, and the insoluble content (% by weight) was determined using the following formula, where the amount of the original composition was Ag, and the weight of the residue after filtration-drying was Bg. Was determined and used as an index for the dissolution test.

Insoluble matter (% by weight) = B / A × 100 (3) Transparency A sheet having a thickness of 0.5 mm was prepared, and the transmittance (%) of ultraviolet light having a wavelength of 360 nm at 5 ° C. was determined using an ultraviolet spectrophotometer. The transparency was evaluated on a scale of ○, Δ, ×.

：: Transmittance 80% to 100% △: Transmittance 60% to less than 80% ×: Transmittance less than 60% (4) Workability Sprinkled on a 4-inch roll (80 to 120 ° C), with poor adhesion The sample was evaluated as × when the sample was hard to be processed due to high adhesiveness or stickiness, and was evaluated as ○ when the sample had no roll sticking property and no shrinkage problem.

(5) Hardness The composition was pressed to form a sheet having a thickness of 3 mm,
A cured product was obtained by performing an exposure treatment for 20 minutes using a UV lamp / cm ² , and the hardness and ΔHs of the cured product were determined in accordance with JIS K-6301.

(6) Rebound resilience The composition was pressed to form an 8 x 8 x 4 mm sheet,
Exposure treatment was performed for 20 minutes using an ultraviolet lamp of mW / cm ² to obtain a cured product, and the elasticity (%) at 25 ° C. and 5 ° C. of the cured product was determined using a Dunlop trypsometer (manufactured by Wallace). The difference was compared.

Example 1 300 g of nonaethylene glycol dimethacrylate as a photopolymerizable unsaturated monomer was added to 100 g of a copolymer having a molar ratio of isoprene units / butyl acrylate units / 2-methacryloyloxyethylsuccinic acid units of 35/50/15, 1.5 g of benzoin methyl ether as a photopolymerization initiator and 0.2 g of hydroquinone as a storage stabilizer were added, and the mixture was kneaded with a Brabender having an internal volume of 200 ml for 10 minutes at 120 ° C. to prepare a photosensitive resin composition. Table 1 shows the physical properties of this product.

Next, the composition was sandwiched between polyethylene terephthalate films having a thickness of 0.1 mm, and 2.0 mm thick using a vacuum press.
Molding was performed so that This photosensitive resin layer maintained its solidity, and there was no problem in handleability.

Next, the polyester protective film was peeled off, a negative film having an optical density of 3.8 was brought into close contact with the surface of the photosensitive resin layer, and exposure was performed for 5 minutes using a commercially available ultraviolet exposure device for photosensitive resin plates. (15mW / cm ^2, 320~400n
m) When the developing treatment was performed using a 1% by weight aqueous solution of sodium hydroxide as a developing solution, the unexposed portions were completely dissolved and removed, and a resin relief plate faithful to the original image was obtained.

Examples 2 to 6, Comparative Examples 1 to 5 Except for using those shown in Table 1 as copolymers,
A photosensitive resin composition was prepared in the same manner as in Example 1. The physical properties are shown in Table 1.

As is clear from Table 1, the use of the copolymers of Examples 1 to 6 according to the present invention makes it possible to obtain a photosensitive resin composition having excellent hardness and low-temperature resilience at low temperatures. I understand.

On the other hand, Comparative Example 1 using a copolymer using an acidic monomer having a low Tg such as methacrylic acid and acrylic acid
In Nos. To 3, there is a problem that the rebound resilience at low temperature is low.
In Comparative Example 4 using a copolymer having a low content of the gen unit, the hardness is too high, whereas in Comparative Example 5 using a copolymer having a too high content of the oxidized monomer unit, the processability is poor. There is.

Example 7 To 100 g of a copolymer having a butadiene unit / butyl acrylate unit / 2-methacryloyloxyethylsuccinic acid unit / divinylbenzene unit molar ratio of 35 / 49.7 / 15 / 0.7, nona was used as a photopolymerizable unsaturated monomer. 300 g of ethylene glycol dimethacrylate, 1.5 g of benzoyl methyl ether as a photopolymerization initiator and 0.2 g of hydroquinone as a storage stabilizer
Was added and kneaded for 10 minutes at 120 ° C. with a Brabender having a content of 200 ml to prepare a photosensitive resin composition. Table 2 shows the physical properties of this product.

Next, the composition was sandwiched between polyethylene terephthalate films having a thickness of 0.1 mm, and a 2.0 m thick film was formed using a vacuum press.
The molding was performed so as to obtain m. This photosensitive resin layer maintained its solidity, and there was no problem in handleability.

Next, the polyester protective film was peeled off, a negative film having an optical density of 3.8 was brought into close contact with the surface of the photosensitive resin layer, and exposure was performed for 5 minutes using a commercially available ultraviolet exposure device for photosensitive resin plates. , (15mW / cm ^2, 320~400
nm) When a developing treatment was performed using a 1% by weight aqueous solution of sodium hydroxide as a developing solution, the unexposed portions were completely dissolved and removed, and a resin relief plate faithful to the original image was obtained.

Examples 8 and 9 Except for using the copolymer shown in Table 2 as the copolymer,
A photosensitive resin composition was prepared in the same manner as in Example 7. The physical properties are shown in Table 2.

[Effects of the Invention] The photosensitive resin composition of the present invention has characteristics such as excellent photosensitivity, processability and alkali developability, and a cured product thereof having excellent water resistance, transparency and rubber elasticity at low temperatures. ,
It is suitably used as a water-soluble photosensitive flexographic printing plate material.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-95349 (JP, A) JP-A-61-128243 (JP, A) JP-A-2-58059 (JP, A) JP-A 63-95 162712 (JP, A) JP-A-1-183551 (JP, A) JP-A-53-10648 (JP, A) JP-A-4-60550 (JP, A) (58) Fields investigated (Int. Cl. ^6, DB name) G03F 7/033 G03F 7/027

Claims (1)

(57) [Claims] (A) (A) 10 to 80 mol% of a conjugated diolefin compound unit, (B) 5 to 40 mol% of an acrylate unit and / or methacrylate unit having an acidic functional group,
(C) Monoolefinic unsaturated compound unit 0 to 80 mol%
And (d) a copolymer comprising 0 to 5 mol% of a polyfunctional vinyl compound unit; (B) a photopolymerizable unsaturated monomer;
(C) A photosensitive resin composition containing a photosensitizer.