JPH03116150A - Photosensitive resin composition and printing plate material using the same - Google Patents

Abstract

PURPOSE:To enable a resin printing plate developable by aqueous solvents and permitting using of aqueous inks, and having flexibility, impact resistance, and elasticity, and capable of obtaining high-grade print quality by using as a base polymer a copolymer comprising polyvinyl alcohol type macromonomer units. CONSTITUTION:The water-insoluble copolymer A to be used as the base polymer comprises the polyvinyl alcohol type macromonomer units and an ethylenically unsaturated carboxylic acid units, and a radically polymerizable ethylenic mono mer and a hotopolymerization initiator are incorporated in the copolymer A, thus permitting the obtained photosensitive resin composition to form the resin printing plate developable by aqueous solvents and permitting use of aqueous inks, and having impact resistance, flexibility, and elasticity, and capable of giving high-grade print quality.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a photosensitive resin composition and a printing plate material using the same.

B. Prior Art Conventionally, a composition containing a polymer serving as a film base, a radically polymerizable ethylenic monomer (hereinafter referred to as a polymerizable monomer), and a photopolymerization initiator is called a photosensitive resin composition, and is used, for example, in letterpress printing plates. Widely used as a material.

The photosensitive resin composition described above is prepared in the form of a sheet on a support such as a metal plate or a film plate (this is referred to as a photosensitive resin plate), and then exposed and developed to become a resin letterpress.

Conventionally, water-developable photosensitive resin compositions using polyvinyl alcohol-based polymers or nylon-based polymers as base polymers have been used, but the water resistance after curing is not necessarily sufficient and water-based inks are difficult to use. There are problems such as unusability.

On the other hand, flexo plates are still mainly of the so-called organic solvent developable type based on 1,2-polybutadiene or styrene-isoprene-styrene block copolymers, and photosensitive resin compositions that are water-developable and can be used with water-based inks. At present, we have not found anything with satisfactory properties.

Problem to be solved by C The present invention is capable of developing with an aqueous solvent, has sufficient water resistance to allow the use of an aqueous ink, is flexible, has impact resistance, and has elasticity. The object of the present invention is to provide a photosensitive resin composition that has sufficient elasticity and flexibility to be used for printing plate materials that can provide high quality printing, particularly for flexographic printing.

As a result of intensive study on the above-mentioned problem, the present inventors have determined that the object can be achieved by employing a copolymer (A) containing polyvinyl alcohol-based macromonomer units as a pace polymer. The heading completes the invention.

The present invention will be explained in detail below.

The present invention is characterized by containing a water-unsaturated soluble copolymer containing a polyvinyl alcohol macromonomer unit and an ethylenically unsaturated carboxylic acid unit, a radically polymerizable ethylenic monomer, and a photopolymerization initiator. shall be.

The copolymer (A) used in the present invention is a polymer that is insoluble in water and soluble in alkaline water, and is composed of the following units (a), (b), and (c). The polyvinyl alcohol macromonomer (a) unit has a number average degree of polymerization of 3 to 5 and has a vinyl alcohol unit content of 50 mol% or more.
00 polyvinyl alcohol-based polymer, the main chain portion connecting the macromonomer units does not need to have a specific structure, such as a methacrylic acid ester structure. An example of the unit (a) is a macromonomer unit represented by the following general formula (a-1), which exhibits good copolymerizability during production and does not have relatively strong hydrophobic properties.

Hs Here, -R'-S- is a linking group between the methacrylic acid ester part and the polyvinyl alcohol polymer part, and R
1 is an alkylene group having 2 to 20 carbon atoms which may have a branch, and S is a sulfur atom. A specific example of R1 is -(cHt)t--(cHt)3(CH=)s
(CHt) lo CH(CaHls)C
HtC)I(C+oHt+)CHt- and the like.

(PVA) is a monovalent polyvinyl alcohol polymer having a number average degree of polymerization of 3 to 5001, preferably 5 to 300, and a vinyl alcohol content of 50 mol% or more. The type and amount of units other than vinyl alcohol units constituting the monovalent polyvinyl alcohol polymer are not particularly limited as long as they are less than 50 mol%, and are selected from units that can be introduced, for example, by copolymerization or polymer reaction.

Examples of such units include:

That is, olefins such as ethylene, propylene, 1-butene, isobutyne, vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl persate, vinyl laurate, vinyl stearate, vinyl benzoate, etc. Vinyl esters, acrylic acid or its salts, methyl acrylate, ethyl acrylate, n-propyl acrylate, propyl acrylate,
Acrylic acid esters such as n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadenyl acrylate, methacrylic acid or its salts, methyl methacrylate, methacrylic acid Methacrylic acid esters such as ethyl, n-propyl methacrylate, l-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, monobutyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and octadecyl methacrylate. acrylamide, N-methylacrylamide, N-ethylacrylamide, N.

N-dimethylacrylamide, diacetone acrylamide, acrylamide propane sulfonic acid or its salt,
Acrylamidopropylzmethylamine or its salts and quaternary salts thereof, acrylamide derivatives such as N-methylolacrylamide or its derivatives, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts , methacrylamide propyl dimethylamine or its salt and its quaternary salt, methacrylamide derivatives such as N-methylolacrylamide or its derivatives, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-brobyl vinyl ether, n
-butyl vinyl ether, i-butyl vinyl ether,
butyl vinyl ether, dodecyl vinyl ether,
Vinyl ethers such as stearyl vinyl ether, nitriles such as acrylonitrile and methacrylonitrile, vinyl halides such as vinyl chloride, hnylidene chloride, vinyl fluoride, and vinylidene fluoride, allyl compounds such as allyl acetate and allyl chloride, maleic acid or These include salts thereof and esters thereof, itaconic acid or salts thereof and esters thereof, vinylsilyl compounds such as vinyltrimethoxysilane, isopropenyl acetate, and the like.

There is no particular restriction on the content of the polyvinyl alcohol macromonomer (a) unit, but depending on the case, 50w
If it exceeds t%, problems will occur in water resistance, and if it is less than 3wt%, the strength reinforcement and crosslinking effects described below may not be achieved, so the content is preferably 3 to 50wt%.

As the ethylenically unsaturated carboxylic acid (b), acrylic acid, methacrylic acid, crotonic acid, itaconic acid or its monoester and its monosalt, maleic acid or its monoester and its monosalt, fumaric acid or its monoester and its monosalt. There is no particular restriction on the content of ethylenically unsaturated carboxylic acid (b), but in some cases, if it is less than 1 wt%, sufficient developability with aqueous solvents may not be obtained, and conversely, if it exceeds 20 wt%, developability may be impaired. is not a problem, but it may cause problems such as poor water resistance and hardness of the plate, so it is preferably 1 to 20.
vt%. The molecular weight of the copolymer (A) is appropriately selected in consideration of the balance between film formability and developability.

(a) Units and (b) Other units other than units (c)
is a unit constituting the main chain of the copolymer, and is composed of ethylenic monomer units other than the (a) unit and (b) unit, and there is no particular restriction on its content, but it is from 30 to 96
wt% is preferred. There is no particular restriction on the unit that can be used as the unit (e), and it is appropriately selected depending on the properties of the intended plate material. For example, if high hardness is required, a monomer that increases the glass transition temperature of the polymer is selected; conversely, if flexibility or elasticity is required, a monomer that lowers the glass transition temperature is selected. be done. Although the type of plate material is not limited depending on the glass transition temperature of the copolymer (A), examples include the following. Copolymer (A)
When the glass transition temperature is 180 to 30° C., it has rubber elasticity and is particularly suitable for use in water-based flexographic printing plates, and can also be suitably used for letterpress printing. On the other hand, when the copolymer (A) has a glass transition temperature of 30 to 100°C, it is suitably used for letterpress printing. Examples of commonly used units include the following monomer units. That is, olefins such as ethylene, propylene, l-butene, and isobutyne, methyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, and l-methacrylate. Butyl, monobutyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate,
Octadecyl methacrylate, 2-hydroxyethyl methacrylate, 2-dimethylaminoethyl methacrylate or its salt, and its quaternary salt, 2-diethylaminoethyl methacrylate or its salt, and its quaternary salt, methacrylic acid (2-hydroxy) Methacrylic acid esters such as dimethylaminopropyl and 3-trimethoxysilylpropyl methacrylate, styrene, p-methylstyrene, α
- Styrenes such as styrene or its derivatives such as methylstyrene, chloromethylstyrene, p-styrenesulfonic acid or its salts, p-hydroquinestyrene or its derivatives, acrylamide, N-methylacrylamide,
N-ethylacrylamide, N,N-dimethylacrylamide, diacetone acrylamide, acrylamide propane sulfonic acid and its salts, acrylamide propyldimethylamine or its salts and its quaternary salts, N-
Acrylamide derivatives such as methylolacrylamide or its derivatives, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid or its salt, methacrylamidepropyldimethylamine or its salt and its 4
methacrylamide derivatives such as N-methylolmethacrylamide or its derivatives, nitriles such as acrylonitrile and metacyclonitrile, vinyl chloride, vinylidene chloride, vinyl fluoride, vinyl halides such as vinylidene fluoride, isopropenyl acetate , N-vinylpyrrolidone, etc., as well as macromonomers such as polyoxyalkylene, polyoxyalkylene phosphate, polystyrene, polymethyl methacrylate, and polysiloxane.

As the radically polymerizable ethylenic monomer (B) used as the polymerizable monomer in the present invention, any monomer that can be radically polymerized with a photopolymerization initiator can be used. Those having good compatibility with the copolymer (A) and the photopolymerization initiator (C) are preferably used, and examples of such materials include the following. That is, alkylene glycols and polyalkylene glycols represented by ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, polytetramethylene glycol, copolymers of ethylene glycol and propylene glycol, etc. Monoacrylic ester, monoalkyl monoacrylic ester, diacrylic ester, monomethacrylic ester, monoalkyl monomethacrylic ester, dimethacrylic ester, N-2-oxyethylacrylamide, N-2-oxydimethacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N-3-oxypropylacrylamide, N-3-oxypropyl methacrylamide, N,N-
Bis(2-oxyethyl)acrylamide, N,N-bis(2-oxyethyl)methacrylamide, N-p-oxycyphenylacrylamide, N-p-oxycyphenylmethacrylamide, acrylamide, methacrylamide, m-xylylenebisacrylamide, m-xylylenebismethacrylamide, p-xylylenebisacrylamide, p-quinrylenebismethacrylamide, m-phenylenebisacrylamide, m-phenylenebismethacrylamide, ethylenediaminebismethacrylamide, ethylenediaminebismethacrylamide, hexamethylenebisacrylamide, hexa These monomers include acrylamide derivatives such as methylene bismethacrylamide, methacrylamide derivatives, and the like, and these monomers may be used alone or in combination.

The photopolymerization initiator (C) used in the present invention may be one that dissolves in the system of the copolymer (A) and ethylenic monomer (B) described above, such as benzophenone, benzoin, p, p -Trimethylbenzoin, benzoin methyl ether, benzoin isopropyl ether, acyloin or nuclear substituted aromatic acyloin or acyloin alkyl ether, diacetyl, benzyl, ketocarbonyl compound, 1.1-azocyclohexanecarbonitrile, azonitrile, 9.10-anthraquinone , chloroanthraquinone, 1,4-naphthoquinone, 9゜10-
Examples include phenanthroquinone.

The photosensitive resin composition containing the copolymer (A), the ethylenic monomer (B), and the photopolymerization initiator (C) of the present invention contains 30 to 250 parts by weight of (B) per 100 parts by weight of component (A). , component (C) is preferably used in a range of 0.01 to 15 parts by weight. Furthermore, (A), (B) and (C)
There is no problem in using other components, such as ordinary polyvinyl alcohol polymers and polyamide polymers, within the scope of the invention. In addition, for the purpose of improving the storage stability of the photosensitive resin composition, it may contain a known thermal polymerization inhibitor or storage stabilizer, and if necessary, it may contain colorants, pigments, plasticizers, etc. It may contain additives. Further, a basic compound may be added to improve developability in an aqueous solvent or to promote a photoeffect, such as NaOH-NaC0t, triethanolamine, methylnoethanolamine, dimethylaminoethanol, and the like.

The photosensitive resin composition of the present invention is usually cast onto a support such as a metal plate, plastic plate, rubber plate, glass plate, etc. by casting from alkaline water, alcohol, or other solvents, hot melt molding, or hot extrusion molding. It is formed into a sheet and used.

E. Examples Hereinafter, the present invention will be explained in more detail with reference examples and examples, but the present invention is not limited by these in any way. In addition, "part" and "%" in reference examples and examples
represent "parts by weight" and "% by weight", respectively, unless otherwise specified.

Reference Example 1 2,400 parts of vinyl acetate monomer and 600 parts of methanol were charged into a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, and degassed by bubbling nitrogen gas for 15 minutes. Separately, thiol initial addition solution prepared by dissolving 0.78 parts of 2-mercaptoethanol in 50 parts of methanol, 2
- A continuous addition solution of thiol was prepared by adding methanol to 60 parts of mercaptoethanol to make the total amount 100 parts by volume, and an initiator solution was prepared by dissolving 1.81 parts of 22'-azobisisobutyronitrile in 50 parts of methanol. , Nitrogen replacement was performed by bubbling nitrogen gas.

The temperature of the reactor was started to rise, and when the internal temperature reached 60° C., a separately prepared initial addition solution of thiol and an initiator solution were added in this order to start polymerization.

Immediately, continuous addition of the thiol solution was started to continue polymerization. Continuous addition of thiol was carried out with the aim of achieving the values shown in the table below in accordance with the increase in solid content concentration in the reactor as the polymerization progressed. The solid content concentration was checked by sampling.

Solid content (%) 10 20 30 4
0 50 continuous addition amount (parts by volume) 15,5 31,
3 47.2 63.1 79.0 Polymerization was carried out for 3 hours while continuously adding thiol, and the polymerization was stopped by cooling. The solid component concentration at this time was 51.0%, and the amount of the thiol solution continuously added was 82.0 parts by volume. Subsequently, unreacted vinyl acetate monomer was removed while occasionally adding methanol under 1 reduced pressure at 30° C. to obtain a methanol solution of polyvinyl acetate. A portion of this methanol solution was poured into ether to recover polyvinyl acetate, which was purified by reprecipitation twice with acetone-ether and then dried under reduced pressure at 40°C. When this purified polyvinyl acetate was measured by proton NMR (measured using GX-500 manufactured by JEOL Ltd., the same applies hereafter) using CDCl3 as a solvent, it was found that the number average degree of polymerization was 31, and the polyvinyl acetate had a structure with a hydroxyl group at one end. It was vinyl acetate.

Reference Example 2 The methanol solution of polyvinyl acetate shown in Reference Example 1 was
Methanol was removed together with toluene under reduced pressure at 40°C to obtain a toluene solution (temperature 63.4%) of polyvinyl acetate having a hydroxyl group at one end. 100 parts of this toluene solution and 4.16 parts of pyridine were placed in a reactor equipped with a stirrer, a reflux condenser, and a dropping funnel, and the mixture was thoroughly stirred at room temperature. Subsequently, 5.50 parts of methacrylic acid chloride distilled just before and 10 parts of dehydrated toluene were placed in a dropping funnel, mixed well, and then uniformly added dropwise over 1 hour while stirring at room temperature. After the dropwise addition was completed, stirring was continued for an additional 3 hours at room temperature. Next, 1.70 parts of methanol was added and stirred for 1 hour, and then toluene, methanol, etc. were distilled off at 40°C under reduced pressure while adding 400 parts of toluene in 4 portions, and the white precipitate formed was filtered. 53.2% after removing
A toluene solution of was obtained. A portion of this toluene solution was poured into hexane to recover polyvinyl acetate, and acetone
After reprecipitation purification with hexane twice, the product was dried under reduced pressure at 40°C. When this purified polyvinyl acetate was measured by proton NMR using CDCl3 as a solvent, it was found to be a polyvinyl acetate macromonomer having the following structure with a number average degree of polymerization of 31 and a methacrylic acid ester structure at one end.

CI’t.

CH,=C C-0-CHICH,-5(CH,-CH)n-HI3 0 0 COCH
G20)1. ) ISG-40H and usc-60S
(manufactured by Shimadzu Corporation).
HF solvent, flow rate 1.0 min/min, measured at 25°C (
The following measurements were also carried out under the same conditions), and the ratio of the weight average degree of polymerization to the number average degree of polymerization was P w / P n = 2.2.

Example 1 A toluene solution of the polyvinyl acetate macromonomer (number average degree of polymerization of the polyvinyl acetate portion: 31) obtained in Reference Example 2 was placed in a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer. Concentration: 48.5%) 61.9 parts, lauryl methacrylate 54 parts, methacrylic acid 6 parts, and toluene 48 parts
．． One part was charged, and nitrogen substitution was performed by bubbling nitrogen gas at room temperature. Start heating up the reactor, and when the internal temperature reaches 60°C, 2.2-azobisisobutyronitrile 0.
．． Polymerization was started by adding an initiator solution in which 09 parts of toluene was dissolved in 10 parts of toluene and replaced with nitrogen, and the polymerization was continued for 20 hours with stirring. After the polymerization was terminated, the polymerization solution was poured into excess methanol, the resulting polymer was recovered, purified by repeating toluene-methano reprecipitation, and dried. The approximate weight average molecular weight of polystyrene measured by GPC in tetrahydrofuran is 125,000.
Met. Subsequently, 10 parts of this polymer was dissolved in 71 parts of tetrahydrofuran, the temperature was adjusted to 40°C, and 29 parts of a methanol solution of sodium hydroxide of LOvt% was added to decompose the vinyl acetate unit with methanol.

After the reaction was completed, it was washed with acetic acid and methanol and dried to obtain a polymer (copolymer 1) consisting of 21.3 wt% polyvinyl alcohol macromonomer units, 70.8 wt% methacrylic acid units, and 7.9 wt% lauryl methacrylate units. Obtained.

(a) Copolymer 1100 parts (b) Ethylene glycol methafrylate 4
0 parts 2-ethylhexyl methacrylate 1
0 parts (C) Benzoin isopropyl ether
10 parts methylhuman quinone
0.5 parts of each of the above ingredients were placed in a pressurized Neegoo and kneaded for 15 minutes under heating at 70°C, followed by press molding on an aluminum plate to obtain a 0.5 mm thick photosensitive resin plate. A negative was attached to this resin plate and irradiated with a mercury lamp with a wavelength of 320 to 400 mμ for 3 minutes, and the unexposed area was covered with NaO2 at 25°C.
After washing with an aqueous H solution for 5 minutes and then an aqueous acetic acid solution, halftone reproducibility was observed.

In addition, the resin plate was irradiated with a mercury lamp having a wavelength of 320 to 400 a+μ for 10 minutes to obtain a cured product that was fully exposed.
The flexibility of the cured films under %RH and elasticity at 20°C were investigated.

The results are shown in Table 1.

Example 2 A polyvinyl acetate macromonomer (number average degree of polymerization of the polyvinyl acetate portion) obtained in the same manner as shown in Reference Example 2 was placed in a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer. 24) Toluene was removed from the toluene solution to make a methanol solution (concentration 48.5%) 108.2
4.8 parts of methacrylic acid, 92.7 parts of polypropylene glycol monomethacrylate and 84.9 parts of methanol.
3 parts were charged, and nitrogen substitution was performed by bubbling nitrogen gas at room temperature. When the temperature of the reactor started to rise and the internal temperature reached 60°C, 0.1 of 2゜2゛-azobisisobutyronitrile was added.
Polymerization was started by adding an initiator solution in which 5 parts were dissolved in 10 parts of methanol and the atmosphere was replaced with nitrogen, and the polymerization was continued with stirring for 20 hours. When measured in the same manner as in Example 1, the polymerization average molecular weight was 153,000. followed by methanol-
The temperature was adjusted to 40° C., and 58 parts of a 10 wt% methanol solution of sodium hydroxide was added to decompose the vinyl acetate unit with methanol. After the reaction is completed, it is washed with acetic acid and methanol and dried to give polyvinyl alcohol macromonomer units of 22.6 wt% and methacrylic acid units of 3.8 wt%.
A polymer (copolymer 2) consisting of 73.6 wt % of polypropylene glycol monomethacrylate units was obtained.

(a) 2100 parts of copolymer (b) Ethyl glycosifu methacrylate
10 parts 2-ethylhexyl methacrylate
41 methyl human alpha quinone
05 parts Each of the above components was molded and tested in the same manner as in Example 1.

The results are shown in Table 1.

Comparative Example 1 As the base polymer, PVA was used instead of copolymer (A).
The test was conducted in the same manner as in Examples and 2 above, except that 205 (degree of polymerization: 550, degree of saponification: 88 mol%) was used. The results are shown in Table 1.

Table 1 (*1) O: Items that do not break even when bent. ×: Items that easily break when bent. (*2) Measured value at 20°C according to JIS-6301 method. O: Items that exhibit rebound resilience. Items that do not exhibit rebound resilience According to the present invention, high-quality printing that can be developed with a water-based solvent and has sufficient water resistance to allow the use of water-based inks, has impact resistance, flexibility, and even elasticity. A photosensitive resin composition that becomes a resin plate that provides quality is obtained. A further advantage of the photosensitive resin is that a photosensitive resin composition can be obtained that has enough elasticity and water resistance to be used as a water-based flexographic printing plate.

Claims (5)

[Claims] (1) Contains a water-insoluble copolymer (A) containing a polyvinyl alcohol macromonomer unit and an ethylenically unsaturated carboxylic acid unit, a radically polymerizable ethylenic monomer (B), and a photopolymerization initiator (C) A photosensitive resin composition characterized by: (2) Photosensitivity according to claim 1, wherein the copolymer (A) has a polyvinyl alcohol macromonomer unit content of 3 to 50% by weight and an ethylenically unsaturated carboxylic acid unit content of 1 to 20% by weight. Resin composition. (3) The photosensitive resin composition according to claim 1 or 2, wherein the copolymer (A) has a glass transition temperature of -80°C or higher and 30°C or lower. (4) The photosensitive resin composition according to claim 1 or 2, wherein the copolymer (A) has a glass transition temperature of higher than 30°C and lower than 100°C. (5) A printing plate material comprising the photosensitive resin composition according to any one of claims 1 to 4.