JPH05232698A - Production of hydrophilic copolymer containing phosphorus and water developable photosensitive composition using this copolymer - Google Patents

Abstract

PURPOSE:To provide a photosensitive compsn. for water development which is soluble in alkali soln. and excellent in workability and light-curing property and can give a hardened body excellent in elasticity at low temp., transparency and water resistance, and especially, is suitable for flexographic printing plate material, and to provide the production method of phosphorus-contg. hydrophilic copolymers to be used for this compsn. CONSTITUTION:This phosphorus-contg. hydrophilic copolymer is obtd. by copolymn. of a mixture with using a radical polymn. initiator. The mixture consists of (1) 70-98wt.% monoolefin unsatd. monomers, (2) 2-30wt.% unsatd. monomers containing phosphate groups, and (3) 0-10wt.% of polyfunctional vinyl compd. The photosensitive compsn. for water development consists of the phosphorus-contg. hydrophilic copolymer (A), photopolymerizable unsatd. monomer (B) and photosensitizer (C).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a phosphorus-containing hydrophilic copolymer and a novel photosensitive composition for water development using the hydrophilic copolymer obtained by this method. More specifically, the present invention radically copolymerizes a phosphorus-containing hydrophilic copolymer with a monoolefin-based monomer, a phosphoric acid ester group-containing unsaturated monomer, and an optional polyfunctional vinyl compound. A method for efficiently producing the compound by the method, and comprising the phosphorus-containing hydrophilic copolymer obtained by this method, having good photosensitivity, processability and developability in an alkaline aqueous solution, and having elasticity at low temperature and transparency. The present invention relates to a photosensitive composition for water development which gives a cured product having excellent properties and water resistance and is suitable as a material for a photosensitive flexographic plate.

[0002]

2. Description of the Related Art Conventionally, as a plate material for flexographic printing,
For example, a rubber casting plate produced by heat-pressing a thermosetting resin into a master plate obtained by etching a metal plate to form a mother mold, and then pouring rubber into the mother mold and pressurizing it, styrene-butadiene rubber, With synthetic rubber such as acrylonitrile-butadiene rubber as the main resin component,
There is known a photosensitive resin plate obtained by making a photosensitive resin composition containing a photopolymerizable monomer having an ethylenic double bond at the end thereof. However, the former rubber plate has drawbacks that it takes a long time for plate making, the manufacturing cost is high, and the image reproducibility of the plate itself is poor. On the other hand, the latter photosensitive resin plate containing synthetic rubber as a main resin component is inferior in solvent resistance, abrasion resistance and durability, and is used as a developing solution at the time of plate making, for example, halogenation of 1,1,1, -trichloroethane or the like. The use of hydrocarbon has drawbacks such as deterioration of working environment. In order to improve such a defect, various photosensitive resin compositions for flexographic printing plates having water developability have been proposed in recent years (Japanese Patent Laid-Open Nos. 54-110287 and 61-22339). .. However, these compositions are not practical because they use water / alcohol / alkali-based special developers for development, require heating, and have a markedly slow developing rate. Moreover, recently
A copolymer of a conjugated diolefin hydrocarbon, an α, β-ethylenically unsaturated carboxylic acid and a monoolefin unsaturated compound optionally used, a photopolymerizable unsaturated monomer and a photosensitizer A photosensitive resin composition containing the same has been proposed (Japanese Patent Publication No. 59-29849). However, although this composition has various advantages over the conventional ones, it is not always satisfactory in terms of processability, transparency of the cured product, elasticity at low temperatures, etc., especially in cold regions. , The printing plate obtained has increased hardness,
There is a problem that it cannot be used as a flexographic plate.

[0003]

DISCLOSURE OF THE INVENTION The present invention overcomes the drawbacks of the conventional photosensitive resin composition, is soluble in an alkaline aqueous solution, is excellent in processability and photocurability, and is low in temperature. Of a photosensitive composition for water development, which gives a cured product excellent in elasticity, transparency and water resistance at the time, and is particularly suitable as a material for flexographic printing plates, and a phosphorus-containing hydrophilic copolymer used in this composition. The purpose is to provide a manufacturing method.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have found that a monoolefin unsaturated monomer and a phosphate ester group-containing unsaturated monomer are essential components. And, if desired, by radical copolymerizing a mixture containing a polyfunctional vinyl compound in a specific proportion, the phosphorus-containing hydrophilic copolymer preferably used in the photosensitive composition for water development is efficiently prepared. What is obtained, and a composition comprising the phosphorus-containing hydrophilic copolymer, a photopolymerizable unsaturated monomer, and a photosensitizer, is a photosensitive composition for water development having the above-mentioned preferable properties. Therefore, the present invention has been completed based on this finding.

That is, the present invention comprises: (a) 70 to 98% by weight of a monoolefinic unsaturated monomer, (b) 2 to 30% by weight of a phosphoric acid ester group-containing unsaturated monomer, and (c) a large amount. A method for producing a phosphorus-containing hydrophilic copolymer, which comprises copolymerizing a mixture of 0 to 10% by weight of a functional vinyl compound with a radical polymerization initiator, and (A)
A phosphorus-containing hydrophilic copolymer obtained by the production method,
The present invention provides a photosensitive composition for water development containing (B) a photopolymerizable unsaturated monomer and (C) a photosensitizer.
Hereinafter, the present invention will be described in detail.

In the production of the phosphorus-containing hydrophilic copolymer in the present invention, (a) a monoolefin unsaturated monomer and (b) a phosphoric acid ester group-containing unsaturated monomer are essential as raw material monomers. It is used as a component, and optionally (c) a polyfunctional vinyl compound is used in combination. (A)
Examples of the monoolefin unsaturated monomer as the component include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, n-
Octyl acrylate, dodecyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate,
Acrylic acid esters such as cyanoethyl acrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate, and corresponding methacrylic acid esters, as well as styrene, acrylonitrile, vinyl chloride, ethylidene norbornene, propenyl norbornene, dicyclopentadiene, and the like. Is 1
One kind may be used, or two or more kinds may be used in combination.

The mono-olefinic unsaturated monomer of the component (a) is 70 to 98% by weight based on the total amount of raw material monomers,
It is necessary to use it in a ratio of preferably 80 to 95% by weight. If this amount exceeds 98% by weight, the content of other components becomes relatively low and the object of the present invention cannot be sufficiently achieved, and if less than 70% by weight, the workability and the strength of the cured product,
Water resistance may decrease. Examples of the phosphoric acid ester group-containing unsaturated monomer of the component (b) include those represented by the general formula:

[0008]

[Chemical 1]

(Wherein R ¹ is a hydrogen atom or a methyl group, R ²
Is a hydrogen atom, a methyl group, a halomethyl group, etc., and m is 1 to 2
A phosphoric acid monoester or a phosphoric acid diester represented by an integer of 3 and n is 1 or 2 can be used.
Specific examples of the phosphoric acid ester group-containing unsaturated monomer represented by the general formula [1] include ethylene phosphate (meth) acrylate, trimethylene (meth) acrylate phosphate, propylene (meth) acrylate phosphate, Tetramethylene (meth) acrylate phosphate, (bis) ethylene (meth) acrylate phosphate, (bis) trimethylene (meth) acrylate phosphate, (bis) tetramethylene (meth) acrylate phosphate, diethylene glycol (meth) acrylate phosphate , Phosphoric acid triethylene glycol (meth) acrylate, phosphoric acid polyethylene glycol (meth) acrylate, phosphoric acid (bis) diethylene glycol (meth) acrylate, phosphoric acid (bis) triethylene glycol (meth) acrylate, phosphoric acid (bis) polyethylene Green Lumpur (meth) acrylate and the like, which may be used singly or may be used in combination of two or more kinds.

The phosphate ester group-containing unsaturated monomer as the component (b) must be used in a proportion of 2 to 30% by weight, preferably 5 to 20% by weight, based on the total amount of the raw material monomers. .. If this amount is less than 2% by weight, the photosensitive composition containing the obtained copolymer will have poor solubility in an aqueous alkaline solution, and if it exceeds 30% by weight, the solubility in an aqueous alkaline solution will be good, but the processability will be poor. The strength and water resistance of the cured product tend to decrease.

The polyfunctional vinyl compound of the component (c) which is optionally used is a compound containing two or more vinyl bonds in one molecule and having an equivalent reactivity. Examples thereof include polyvalent (meth) acrylic acid esters such as ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and propylene glycol di (meth) acrylate, and further divinylbenzene and trivinylbenzene. These may be used alone or in combination of two or more.

The polyfunctional vinyl compound as the component (c) is used in an amount of 0 to 10% by weight, preferably 0.2 to 5% by weight, based on the total amount of raw material monomers. This amount is 0.2
If it is less than 10% by weight, the effect of using the polyfunctional vinyl compound is not sufficiently exhibited, and the transparency and processability of the obtained copolymer are insufficient, and if it exceeds 10% by weight, the strength of the cured product is high. Is declining. In the present invention, the monoolefin unsaturated monomer as the component (a), (b)
The phosphoric acid ester group-containing unsaturated monomer as a component and the polyfunctional vinyl compound as a component (c), which is optionally used, are mixed at a predetermined ratio, and this mixture is radically copolymerized by using a radical polymerization initiator. As a result, a desired phosphorus-containing hydrophilic copolymer can be produced.

Further, a molecular weight regulator is usually used for controlling the molecular weight, and the amount used is 100 in total of all monomers.
It is preferably selected in the range of 0.1 to 5 parts by weight per part by weight. Further, the total amount of each of the monomers and the polymerization agent such as the radical initiator may be added before the start of the reaction, or may be added in arbitrary divided portions after the start of the reaction. The polymerization is usually carried out in an atmosphere of an inert gas such as nitrogen at a temperature in the range of 0 to 80 ° C., but operating conditions such as temperature and stirring can be arbitrarily changed during the reaction. As the polymerization system, either a continuous system or a batch system can be used. The polymerization method is not particularly limited, and any method conventionally used in radical polymerization such as emulsion polymerization method, suspension polymerization method and solution polymerization method can be used.

Examples of the radical initiator used in this radical polymerization include organic peroxides such as benzoyl peroxide, cumene hydroperoxide and lauroyl peroxide, diazo compounds such as azobisisobutyronitrile, and inorganic compounds such as potassium persulfate. , A redox catalyst composed of a combination of an organic compound and iron sulfate, and the like, and examples of the molecular weight modifier include t-dodecyl mercaptan, dialkylxanthogen disulfide, and the like. The photosensitive composition for water development of the present invention is
Containing the phosphorus-containing hydrophilic copolymer obtained as described above as the component (A), a photopolymerizable unsaturated monomer as the component (B), and a photosensitizer as the component (C) It is necessary to.

Examples of the photopolymerizable unsaturated monomer as the component (B) include aromatic vinyl compounds such as styrene, α-methylstyrene, m-methylstyrene and p-methoxystyrene, acrylonitrile and methacrylonitrile. Unsaturated nitrile compound, methyl (meth) acrylate,
Alkyl alcohol (meth) acrylates such as ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-hydroxyethyl (meth). ) Acrylate, 2-
Hydroxyalkyl alcohol (meth) acrylates such as hydroxypropyl (meth) acrylate, alkoxyalkylene glycol (meth) such as methoxyethylene glycol and methoxypropylene glycol
Acrylates, monoesters of unsaturated polycarboxylic acids such as monoethyl maleate, monomethyl fumarate, monoethyl itaconate, dimethyl maleate, diethyl maleate, dibutyl maleate, dioctyl maleate, diethyl fumarate, dibutyl fumarate. , Dioctyl fumarate, dimethyl itaconate, diethyl itaconate,
Diesters such as dibutyl itaconate, dioctyl itaconate, acrylamide, methacrylamide, N, N '
-(Meth) acrylamides such as methylenebisacrylamide, N, N'-hexamethylenebisacrylamide, ethylene glycol di (meth) acrylate, polyalkylene glycol (alkylene glycol unit 2 to
23) di (meth) acrylate, glycerin, pentaerythritol, trimethylolalkane, tetramethylolalkane (as alkane, methane, ethane,
Propane) and other polyhydric alcohols such as di (meth) acrylate, tri (meth) acrylate, tetra (meth) acrylate, oligo (meth) acrylates, 2- (meth) acryloyloxyethylsuccinic acid, 2- (meth)
Examples thereof include (meth) acrylates having an acidic functional group such as acryloylethylhexahydrophthalic acid and 2- (meth) acryloyloxyethyl acid phosphate.

These photopolymerizable unsaturated monomers may be used alone or in combination of two or more, and the compounding amount thereof is usually 100 parts by weight of the copolymer of the component (A). 5 to 400 parts by weight, preferably 10 to 300 parts by weight. If this amount is less than 5 parts by weight, the curing may be insufficient and the mechanical properties of the cured product may be inferior. If it exceeds 400 parts by weight, the rubber elasticity and solvent resistance of the cured product may tend to decrease. , Not preferable. further,
In the composition of the present invention, the photosensitizer used as the component (C) is usually used as a photoreaction initiator, for example, α-diketones such as diacetyl and benzyl, acyloins such as benzoin and pivaloin, and benzoin. Examples thereof include acyloin ethers such as methyl ether, benzoin ethyl ether and benzoin isopropyl 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 addition amount thereof is usually 0.1 to 10 parts by weight per 100 parts by weight of the copolymer of the component (A). , Preferably 1 to 5 parts by weight. If this amount is less than 0.1 part by weight, a sufficient cured product cannot be obtained, and if it exceeds 10 parts by weight, it is uneconomical because all of the added photosensitizer does not participate in the reaction, and the exposed active light It is not preferable because the reaction rate tends to be slowed by the absorption of

A storage stabilizer may be added to the composition of the present invention, if desired. Examples of the storage stabilizer include hydroquinone, p-methoxyphenol, pt-
Butyl catechol, 2,6-di-t-butyl-p-cresol, hydroxyaromatic compounds such as pyrogallol,
Examples thereof include quinones such as benzoquinone, 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 addition amount thereof is usually (A) Component Copolymer 1
It is selected in the range of 0.01 to 2 parts by weight per 00 parts by weight. One of the characteristics of the composition of the present invention is developability with a dilute aqueous alkali solution. Examples of the dilute alkali used as the developing solution include sodium hydroxide,
A low-concentration aqueous solution of about 0.1 to 4.0% by weight of potassium hydroxide, lithium hydroxide, ammonia, lithium carbonate and the like can be mentioned.

The composition can be developed not only by such a dilute aqueous alkali solution, but also by a mixed solvent of an aqueous alkali solution and an alcohol, a ketone or the like. Since the photosensitive composition of the present invention has high photosensitivity, it requires only a short exposure time and has extremely high solubility in a dilute alkaline aqueous solution, so that it can be developed in about 1 to 5 minutes and, after drying, It has features such as immediate printing, and by using this composition, the plate-making process is simpler and the working time is drastically shortened as compared with the conventional plate making of flexographic printing rubber plates. be able to. Further, the flexographic printing plate obtained by using the composition of the present invention,
Needless to say, it is possible to print with a solvent-type flexo ink, but since it has good water resistance, it is possible to print with a water-based flexo ink that is being used in place of the solvent-type flexo ink from the viewpoint of air pollution.

[0019]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto. The physical properties of the composition were determined as follows. (1) Workability Wrap it around a 6-inch roll (80 to 120 ° C), and those with poor wrapping property or those with severe tackiness that are difficult to process x, those with no problems with roll wrapping and shrinkage. ○ (2) Water resistance A cured product that has been exposed for 10 minutes on both sides without passing through a negative film is punched out into a disk with a diameter of 3 cm, and ethanol / water = 10 /
Swelling degree (wt%) by immersing in a 90 wt% solution for 24 hours
Was measured. (3) Developability A composition having a thickness of 3 mm was prepared by pressing the unexposed photosensitive layer in a 1% by weight sodium hydroxide aqueous solution at 40 ° C. with a nylon brush until it was dissolved by 1 mm. It was time. (4) Hardness The composition is pressed to form a sheet having a thickness of 3 mm, and the sheet is 5 m
Using a W / cm ² ultraviolet lamp, the back and front were exposed for 10 minutes to obtain a cured product. The hardness of this cured product is JISK-630.
It was measured according to 1.

Example 1 Polymerization was carried out at 50 ° C. in an autoclave having an internal volume of 10 liters using the monomers and polymerization agents shown below.

In the polymerization, a terminating agent was added at the time when all the added monomers reached 95%, and after cooling with water, an emulsion-polymerized emulsion was obtained. This emulsion was freeze-coagulated to separate crumbs, washed with water, and vacuum dried at 60 ° C. to obtain a sample for evaluation. Next, with respect to 100 g of this copolymer,
20 g of nonaethylene glycol dimethacrylate as a photopolymerizable unsaturated monomer, 20 g of nonaethylene glycol acrylate, 1.5 g of benzoin methyl ether as a photopolymerization initiator, and hydroquinone of 0.2 as a storage stabilizer.
g, and with a Brabender with an internal volume of 200 ml for 10 minutes,
A photosensitive composition was prepared by kneading at 80 ° C. The physical properties of this product are shown in Table 1. Next, the composition was sandwiched between 0.1 mm-thick polyethylene terephthalate films, and molded using a vacuum press to a thickness of 3.0 mm.
The photosensitive composition retained solidity and had no problem in handleability. Then, the polyethylene terephthalate 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 layer, and exposure was carried out for 5 minutes with a commercially available ultraviolet exposure machine for photosensitive resin ( 5 mW / cm ² , 320 to 400 nm) When 1% by weight sodium hydroxide aqueous solution was used as a developing solution for development processing,
The unexposed area was completely dissolved and removed, and a resin letterpress faithful to the original image was obtained. The resin plate had rubber elasticity and had a hardness (Shore-A, measured at 20 ° C.) of 55.

Examples 2 to 6 and Comparative Examples 1 to 3 Photosensitive compositions were prepared in the same manner as in Example 1 except that the copolymers shown in Table 1 were used. The physical properties are shown in Table 1.

[0023]

[Table 1]

As is clear from Table 1, Examples 1 to 6
By using the copolymer according to the present invention, a photosensitive composition excellent in processability, alkaline aqueous solution developability, water resistance, and hardness of a cured product can be obtained. This is a water-soluble photosensitive flexo. It is suitable as a plate material. On the other hand, in Comparative Examples 1 to 3 using the copolymer obtained by using an acidic monomer such as methacrylic acid and acrylic acid, processability,
There is a problem of poor developability.

[0025]

According to the method of the present invention, a radical copolymerization of a monoolefinic unsaturated monomer, a phosphoric acid ester group-containing unsaturated monomer and a polyfunctional vinyl compound optionally used is carried out at a predetermined ratio. Thereby, the phosphorus-containing hydrophilic copolymer preferably used in the photosensitive composition for water development can be efficiently obtained. The water-developable photosensitive composition of the present invention containing the phosphorus-containing hydrophilic copolymer is excellent in photosensitivity, processability and alkaline aqueous solution developability, and the cured product thereof is water resistant, transparent and at low temperature. It has characteristics such as excellent rubber elasticity and is suitably used as a water-soluble photosensitive flexographic plate material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03F 7/028 7/038

Claims (2)

[Claims] 1. (a) Mono-olefin unsaturated monomer 70
To 98% by weight, (B) 2 to 30% by weight of a phosphoric acid ester group-containing unsaturated monomer, and (C) a polyfunctional vinyl compound 0
A method for producing a phosphorus-containing hydrophilic copolymer, which comprises copolymerizing a mixture of 10 to 10% by weight with a radical polymerization initiator. 2. A water containing (A) a phosphorus-containing hydrophilic copolymer obtained by the method according to claim 1, (B) a photopolymerizable unsaturated monomer and (C) a photosensitizer. Photosensitive composition for development.