JPS6048020B2 - Photosensitive resin composition for printing plates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photosensitive resin composition for printing plates.

An object of the present invention is to provide a resin composition for flexographic printing plates which is required to have low hardness and high strength, and which has improved photosensitive speed, formation of rough edges, and cutting. The present inventors have already conducted intensive research to obtain a low hardness and high strength resin for printing plates, especially a photosensitive resin suitable for flexographic printing plates. By using polyalkylene glycol and aromatic oligoester (B) as compounds having two or more active hydrogen groups in the molecule that can react with cyanate groups, polyalkylene glycol can be used as a part of polyalkylene glycol (2). It has been found that by using tetramethylene glycol, a photosensitive resin composition for printing plates that can be developed with an aqueous solvent and has extremely excellent physical properties can be obtained.
However, although the above-mentioned photosensitive resin compositions for printing plates have excellent physical properties, there are some problems with photosensitivity, such as insufficient shoulder formation in relief and concave tops of relief characters. It has been found that there is a drawback that so-called cupping occurs and ink unevenness occurs when the intermediate pressure is low. The inventors of the present invention have conducted extensive research to improve this point, and have found that by incorporating a liquid polybutadiene compound, the photosensitive speed increases, the formation of shoulders is easy, and at the same time, cutting does not occur. Heading The present invention has been arrived at.

That is, the present invention provides urethane-modified acrylate (i)
, copolymerizable monomer (ii), photosensitizer (iii) and liquid polybutadiene (iv) having a molecular weight of 500 to 5000.
The urethane-modified acrylate (i) is composed of a polyalkylene glycol having a molecular weight of 400 to 5000 and an aromatic oligoester (B) having a molecular weight of 200 to 2000, and (2)/(B) is a molar ratio. 411-1
14, and IAJ/(B) is 1.
A photosensitive resin composition characterized by being a compound having two or more active hydrogen groups in the molecule that can react with zero or more incyane groups, an organic diisocyanate, and an acrylate compound containing an alcoholic hydroxyl group. There are things.

The urethane-modified acrylate (1) in the present invention is:
It is a polymer that has at least two acryloyloxy groups and/or methacryloyloxy groups at the end of the molecule and at least four urethane bonds in the molecule. It is a curable resin that is blended with monomers.

The urethane-modified acrylate (1) is derived from a compound having two or more active hydrogen groups in the molecule that can react with an incyanate group, an organic diisocyanate, and an acrylate compound containing an alcoholic hydroxyl group.

There are 2 active hydrogen groups in the molecule that can react with incyanate groups.
Polyalkylene glycols and aromatic oligoesters are used as the compounds having more than 100% polyalkylene glycol. In the present invention, the urethane-modified acrylate (1) has a molecular weight of 400 to 5.
000 polyalkylene glycol (4) and an aromatic oligoester (B) having a molecular weight of 200 to 2000, the molar ratio of (A)/(B) is in the range of 411 to 114, and (A)/( B) is a compound having two or more active hydrogen groups in the molecule that can react with an incyanate group having a weight ratio of 1.0 or more, and a compound derived from an organic diisocyanate and an alcoholic hydroxyl group-containing acrylate compound.

The polyalkylene glycol (4) has a molecular weight of 40
0-5000 polyethylene glycol, molecular weight 400
~5000 polypropylene glycol, molecular weight 500
Polytetramethylene glycol, molecular weight ~3000.
500-5000 ethylene glycol-propylene glycol block copolymers, ethylene glycol-tetramethylene glycol copolymers with molecular weights 500-3000, propylene oxide of glycerin and/or ethylene oxy. adduct,
Propylene oxide or/and ethylene oxide adduct of pentaerythritol with a molecular weight of 400 to 3,000, propylene oxide or/and ethylene oxide adduct of trimethylolpropane with a molecular weight of 400 to 3,000, propylene oxide or/and ethylene oxide of bisphenol A with a molecular weight of 400 to 2,000. Adducts include propylene oxide and/or ethylene oxide adducts of hydrogenated bisphenol A having a molecular weight of 400 to 2,000.

In addition, if necessary, ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, dichloroneopentyl glycol, dipromoneopentyl glycol, 1,4-butanediol, 1,4
-butenediol, 2,2,4-trimethyl-1,8-
Pentanediol, 1,6-hexanediol, 1,4
- It is also possible to use one part of a low molecular weight polyhydric alcohol such as cyclohexanedimethanol, 1,4-cyclohexanediol, glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. In particular, it is preferable to partially use polytetramethylene glycol with a molecular weight of 500 to 3000 and other polyalkylene glycol, and the proportion of polytetramethylene glycol with a molecular weight of 500 to 3000 in the polyalkylene glycol (4) is 20 to 80 mol. %, and the proportion of other polyalkylene glycols is preferably 80 to 20 mol%. The aromatic oligoester (B) is an oligoester obtained by reacting an aromatic polybasic acid or its derivative with a polyhydric alcohol.

Examples of aromatic polybasic acids include orthophthalic acid, isophthalic acid, terephthalic acid, phthalic anhydride, and naphthalene dicarboxylic acid, with terephthalic acid and its derivatives being particularly preferred. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, diethylene glycol, 1,8-propanediol, 1,3-butanediol, 1,4-butanediol, dipropylene glycol, neopentyl glycol, and 1,4-butene. diol,
1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, dichloroneopentyl glycol, dipromoneopentyl glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, ethylene oxide adduct of bisphenol A, Examples include propylene oxide adduct of bisphenol A, glycerin, trimethylolpropane, and pentaerythritol. The aromatic oligoester (B) can be produced by, for example, direct esterification of an aromatic polybasic acid and a polyhydric alcohol, or by direct esterification of an aromatic polybasic acid derivative such as an aromatic polybasic acid ester and a polyhydric alcohol. Methods include transesterification and depolymerization of high molecular weight aromatic polyesters, such as polyethylene terephthalate and polybutylene terephthalate, with polyhydric alcohols, and known catalysts may be used as necessary during production.

Aromatic oligoester (B) has an acid value of 20 or less and a molecular weight of 2.
It is desirable that it is 00-2000.

When the acid value exceeds 20, the solubility deteriorates, the transparency of the urethane-modified acrylate resin is lost, and the molecular weight exceeds 20.
If it exceeds 00, the viscosity of the urethane-modified acrylate resin becomes extremely high, which may cause problems such as difficulty in handling. As organic diisocyanate compounds,
2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, metaphenylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, bis(isocyanatemethyl)cyclohexane, isophorone diisocyanate, etc.
These organic diisocyanate compounds are used alone or in combination. To obtain the urethane-modified acrylate (1) used in the present invention, first, polyalkylene glycol (4) and aromatic oligoester (B) are reacted with an organic diisocyanate compound to obtain a urethane prepolymer containing terminal isocyanate groups, and then A urethane-modified acrylate is obtained by reacting this terminal isocyanate group-containing urethane prepolymer with an alcoholic hydroxyl group-containing acrylate or methacrylate.

As a method for producing a urethane prepolymer containing terminal isocyanate groups, (1) polyalkylene glycol (4) and aromatic oligoester (B) are mixed with an organic diisocyanate compound in an equivalent ratio of (0H group + 000H group)/NCO group x 1 (equivalent ratio). (2) polyalkylene glycol (A) (or aromatic oligoester (
B)) and an organic diisocyanate compound (0H group+0
00H group)/NCO group x 1 (equivalent ratio), the aromatic oligoester (B) (or polyoxyalkylene glycol (A)) is added to the remaining isocyanate group (0H group + 000H group). )/NCO group (equivalent ratio).

The reaction ratio of the polyalkylene glycol (4) and aromatic oligoester (B) with the organic diisocyanate compound is (0H group + 000H group)/NCO group x 1 (equivalent ratio), preferably 0.3 to 0.8. .

Further, the ratio of polyalkylene glycol (4) to aromatic oligoester (B) is in the range of 411 to 114 in molar ratio, preferably in the range of 311 to 112, and in weight ratio CA
)/(B) 1, preferably (A)/(BKO.6). If the molar ratio of CA)/(B) exceeds 4, the effect of the aromatic oligoester will not be expressed and the strength will be reduced. Only low printing plates are obtained. Furthermore, if the molar ratio of (A)/(B) is less than 11 and the weight ratio is less than 1.0, the viscosity of the urethane-modified acrylate resin will increase, making it difficult to handle, so wash out the exposed areas with a water-based solvent. It will also be extremely difficult. The above reaction is carried out without a solvent or using a solvent inert to isocyanate groups such as styrene, vinyltoluene, ethyl acrylate, methyl methacrylate, benzene, toluene, methylene chloride and the like.

Reaction humidity is 20~120℃, especially 500C~1000C
It is desirable to do so. If necessary, organic tin compound,
Catalysts such as organic amines can also be used. As the alcoholic hydroxyl group-containing acrylate or methacrylate that can react with the terminal isocyanate group-containing urethane prepolymer, for example, ethylene glycol mono(meth)
acrylate, propylene glycol mono(meth)acrylate, 1,3-propanediol mono(meth)acrylenaute, 1,3-butanediol, mono(meth)acrylate, 1,4-butanediol mono(meth)acrylate, 1,6 - Dihydric alcohol mono(meth)acrylate, diethylene glycol mono(meth)acrylate, dipropylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol, mono(meth)acrylate, etc. (meth)acrylate, trimethylolethane mono(meth)acrylate 9 volumes,
Trihydric alcohol mono(meth)acrylate, trimethylolpropane di(meth)acrylate, trimethylolpropane di(meth)acrylate, glycerin mono(meth)acrylate, glycerin di(meth)acrylate, etc. ) acrylates and di(meth)acrylates, or di(meth)acrylates and tri(meth)acrylates of polyhydric alcohols of 4 or more valences such as pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, etc. It will be done.

The reaction ratio of the urethane prepolymer containing a terminal isocyanate group and the acrylate or methacrylate containing an alcoholic hydroxyl group is 0H group/NCO group≧1 (equivalent ratio), preferably 1.05 to 1.3.

The reaction is preferably carried out in the solvent used in the first stage reaction or without a solvent, and the reaction temperature is preferably 80°C or lower. In order to inhibit thermal polymerization in the above reaction, it is desirable to use a known thermal polymerization inhibitor such as hydroquinone, hydroquinone monomethyl ether, t-butylcatechol, p-benzoquinone, or phenothiazine. Urethane-modified acrylate (1) obtained by the above reaction
has a molecular weight of 1,500 to 10,000, preferably 8,
000 to 8,000.

If the molecular weight is less than 1,500, it will be difficult to obtain a rubber elastic body with high hardness, and if the molecular weight exceeds 10,000, the strength will drop significantly and the photosensitive speed will also drop.
Examples of the copolymerizable monomer (Ii) include styrene, vinyltoluene, chlorostyrene, t-butylstyrene,
a-methylstyrene, divinylbenzene, acrylic acid,
Methacrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, 1s0-. Propyl (meth)acrylate, n-
Butyl (meth)acrylate, 1s0-butyl (meth)
Acrylate, Sec-butyl (meth)acrylate,
t-Butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)j acrylate, n-decyl (meth)acrylate, lauryl (meth)acrylate, n-tridecyl (meth)acrylate, stearyl (meth)acrylate acrylate, ethylene glycol mono(meth)acrylate, propylene glycol mono(meth)adacrylate, diethylene glycol mono(meth)acrylate, dipropylene glycol mono(
meth)acrylate, polyethylene glycol mono(meth)acrylate with a molecular weight of 200 to 1000, molecular weight 2
Polypropylene glycol mono(meth)acrylate with a molecular weight of 00 to 1000, polyethylene glycol monomethyl ether mono(meth)acrylate with a molecular weight of 200 to 1000, polypropylene glycol monomethyl ether mono(meth)acrylate with a molecular weight of 200 to 1000, polyethylene glycol mono(meth)acrylate with a molecular weight of 200 to 1000 Ethyl ether mono(meth)acrylate, molecular weight 200
~1000 polypropylene glycol monoethyl ether mono(meth)anocrylate, n-butoxyethyl(meth)acrylate, phenoxyethyl(meth)acrylate, 2-phenoxypropyl(meth)acrylate, cyclohexyl(meth)acrylate, tetrahydrofurfuryl(meth)acrylate ) acrylate, glycidyl (meth)acrylate, allyl (meth)acrylate, benzyl (meth)acrylate, tribromophenyl (meth)
Acrylate, 2,3-dichloropropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, N-t -butylaminoethyl (meth)
Acrylate, acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,3-propanediol di(meth)acrylate, 1,4 butane Diol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, glycerin di(meth)acrylate , glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, ethylenebisacrylmide, diallyl phthalate, triallyl cyanurate, diethyl fumarate, dibutyl fumarate, vinyl acetate, etc. There are several types that are selected depending on the purpose.

Examples of the photosensitizer (III) used in the present invention include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin-1s0-propyl ether, benzoin-n-butyl ether. , diacetyl, benzyl, benzophenone, acetophenone, butyroin, trioin, fluorescein, eosin, erythrosin, a
-Mercaptobenzothiazole, 2-mercaptobenzoxazole, diphenyl disulfide, dibenzyl disulfide, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, 1-naphthalenesulfonyl chloride, 9,10-anthraquinone, 1,
Examples include 4-naphthoquinone.

Liquid polybutadiene compound used in the present invention (1v
) is, for example, a butadiene homopolymer, a butadiene-styrene copolymer, a butadiene-acrylonitrile copolymer, and a derivative thereof having a molecular weight of 500 to 5,000, and is a compound represented by the following general formula.

(In the formula, X=-H1-0H1-COOHl-NH2 group, Y
=-CH=CH2, -C6H5, -CN group, a+b=I
n'+10 to 100.

) The photosensitive resin composition for printing plates of the present invention comprises a urethane-modified acrylate (1), a copolymerizable monomer (Ii), a photosensitizer (Iiii) and a liquid polybutadiene compound (Iv).
).

Urethane-modified acrylate (1) and copolymerizable monomer (I
The mixing ratio of i) is preferably 90:5 to 20:(a) and 80:20 to 40:60 by weight.

The content of photosensitizer (Iil) is 0 based on the total weight of urethane-modified acrylate (1) and copolymerizable monomer (Ii).
．． It is desirable that the amount is 1 to 1% by weight, particularly 0.5 to 5% by weight. In addition, the blending amount of the liquid polybutadiene compound is urethane-modified acrylate (1), copolymerizable monomer (I
The amount is 1 to 5 parts, preferably 5 to 3 parts per 10 parts of the total weight of i) and the photosensitizer (III). If the amount of the liquid polybutadiene compound exceeds 5 parts, the physical properties will be significantly deteriorated and the washout property with a neutral detergent solution will also be impaired. If the amount is less than 1 part by weight, the photosensitive speed, shoulder formation and cutting will not be improved. The light source used for curing the photosensitive resin composition for printing plates of the present invention must be selected appropriately depending on the type of photosensitizer, the type of resin composition, etc. Examples include mercury lamps, high-pressure mercury lamps, carbon arc lamps, xenon lamps, and tungsten lamps.

The photosensitive resin composition for printing plates of the present invention is prepared by using the above-mentioned light source, applying a suitable negative film, exposing it to form a relief image, and washing out the last exposed area using a suitable solvent. A printing plate can be obtained by doing this.

As such a solvent, a neutral detergent aqueous solution is suitable.
By containing a liquid polybutadiene compound, the photosensitive resin composition for printing plates of the present invention has the following properties: (1) It has a high photosensitive speed and does not cause cutting, (2) It can be developed with an aqueous solvent, and (3) A photosensitive resin composition that has many advantages such as (4) excellent ink resistance, and is especially suitable for flexographic printing plates that require rubber elasticity. It is a thing.

Furthermore, it goes without saying that the resin composition of the present invention can be applied to applications such as paints, adhesives, vibration-proofing materials, vibration-damping materials, and coating agents by taking advantage of the above-mentioned characteristics.

Next, Examples will be given to further specifically explain the present invention.

Synthesis Example 1 In a reaction vessel equipped with a thermometer, a reflux condenser, and a stirrer,
Polypropylene glycol #2000 (molecular weight 1968
) 394g (4). 2 mol), 39 g (0.1 mol) of terephthalic acid-dipropylene glycol oligoester (acid value 2.8, molecular weight 390), 70 g (0.4 mol) of 2,4-tolylene diisocyanate, and dibutyltin. A reaction was carried out at 80° C. for 4 hours using 0.2 g of dilaurate as a catalyst to obtain a urethane prepolymer containing terminal isocyanate groups.

Next, ethylene glycol monomethacrylate 29
g (0.22 mol) and reacted at 80° C. for 3 hours to obtain a urethane-modified acrylate. 64 parts by weight of the obtained urethane-modified acrylate, 1 part per day of ethylene glycol monomethacrylate, 1 part by weight of lauryl methacrylate, 1 part by weight of n-butoxyethyl methacrylate, and 0.5 part by weight of benzoin methyl ether were mixed and dissolved. This was referred to as a photosensitive resin composition (4). Synthesis Example 2 Add polyprolene glycol #2 to the same reaction vessel as Synthesis Example 1.
000 (minute weight 1968) 197g (0.1 mol), polytetramethylene glycol #2000 (molecular weight 196
8) 197 g (0.1 mol) and 70 g (0.4 mol) of 2,4-tolylene diisocyanate were charged, and 0.2 g of dibutyltin dilaurate was reacted with the catalyst at 80°C for 2 hours. Furthermore, terephthalic acid-dipropylene glycol oligoester (acid value 2.8, molecular weight 390) 39
g (0.1 mol) and reacted for 3 hours at 80'C to obtain a urethane prepolymer containing terminal isocyanate groups.

Next, 29 g (0.22 mol) of ethylene glycol monomethacrylate containing 0.01 g of hydroquinone was charged and reacted at 80° C. for 3 hours to obtain a urethane-modified acrylate. 64 parts by weight of the obtained urethane-modified acrylate, 1 part by weight of ethylene glycol monomethacrylate, 1 part by weight of lauryl methacrylate, 1 part by weight of n-butoxyethyl methacrylate, and 0.5 part by weight of benzoin methyl ether were mixed and dissolved. Photosensitive resin composition (B)
And so. Example 1 and Comparative Example 1 A liquid polybutadiene compound POlybclR45HT (manufactured by Idemitsu Petrochemical) was added to the photosensitive resin compositions (4) and (B) obtained in Synthesis Examples 1 and 2 to prepare the photosensitive resin composition of the present invention. I prepared something.

These photosensitive resin compositions were injected between glass plates sandwiching rubber spacers with a thickness of 3 TWL, and a 140 W mercury lamp was heated for two times.
Irradiation was performed from a distance of 0 cm, and the irradiation time and photocuring thickness (T
f$L). The results are shown in Table 1, and it is clear that the composition of the present invention has a large cured thickness, that is, a high photosensitive speed. Example 2 Liquid polybutadiene compound POlybcl was added to 100 parts by weight of the photosensitive resin composition (A) obtained in Synthesis Example 1.
R45HT (manufactured by Idemitsu Petrochemical) 15 parts by weight, NISSO
A composition obtained by blending 5 parts by weight of PBG2OOO (manufactured by Nippon Soda) was covered with a polyester film to a thickness of 3T!
Pour onto a glass plate sandwiching Un's rubber spacer, apply negative film, and turn on 140W from the opposite side of the negative film.
1. Hold a mercury lamp from a distance of 20 cm. After powder-to-powder irradiation and then 8-minute irradiation from the negative film side, the end-exposed area was brushed and cleaned with a 5% aqueous solution of Mama Lemon, a neutral detergent manufactured by Lion Oil Co., Ltd., to obtain a flexographic printing plate with a clear relief image.

The hardness of the obtained flexographic printing plate was 41 (Shore A), the relief depth was 1.5 mm, and the shoulder angle was 68).
Cutting was also not allowed. Comparative Example 2 The photosensitive resin composition (4) obtained in Synthesis Example 1 was covered with a polyester film to a thickness of 377!7! Pour the negative film onto the glass plate with the rubber spacer in between, and turn on a 140W mercury lamp at 20cm from the opposite side of the negative film.
2 from a distance of m. After irradiating for a short period of time and then irradiating for 12 minutes from the negative film side, the end-exposed area was brushed and cleaned with a 5% aqueous solution of Mama Lemon, a neutral detergent manufactured by Lion Oil Co., Ltd., to obtain a flexographic printing plate.

The hardness of the obtained flexographic printing plate was 46 (Shore A), but the shoulder angle was 87, which was insufficient, and significant cutting occurred in relief images of small characters. Example 3 Liquid polybutadiene compound HycerOTB was added to 100 parts by weight of the photosensitive resin composition (B) obtained in Synthesis Example 2.
Nl3OO×8 (manufactured by Ube Industries) 10 parts by weight, POlyb
A composition obtained by blending 2 parts of clR45HT (manufactured by Idemitsu Petrochemical) was covered with a polyester film to a thickness of 37 cm.
077! Pour the rubber spacer on the glass plate, place the negative film on it, and press it from the side opposite to the negative film.
After irradiating the film with a 40W mercury lamp for 1.5 minutes from a distance of 20 CIrL, and then irradiating it for 1 minute from the negative film side, the last exposed area was cleaned by brushing with a 5% aqueous solution of Mama Lemon, a neutral detergent manufactured by Lion Oil Co., Ltd. to obtain a flexographic printing plate. Ta.

The hardness of the obtained flexographic printing plate was 42 (Shore A), the shoulder angle was 650, and no cutting was observed. Comparative Example 3 The photosensitive resin composition (B) obtained in Synthesis Example 2 was covered with a polyester film to a thickness of 3T$.
A negative film was poured onto a glass plate sandwiching a L rubber spacer, and a 140W mercury lamp was irradiated from the opposite side of the negative film for 4 minutes from a distance of 20cm.Then, after irradiating the negative film for 1 time, the final exposed area was exposed. A flexographic printing plate was obtained by brushing and cleaning with a 5% aqueous solution of Mama Lemon, a neutral detergent manufactured by Lion Oil Co., Ltd.

Claims (1)

[Claims] 1 Urethane modified acrylate (i), copolymerizable monomer (ii), photosensitizer (iii) and molecular weight 500-5
000, and the urethane-modified acrylate (i) has a molecular weight of 400.
~5000 polyalkylene glycol (A) and molecular weight 200~2000 aromatic oligoester (B)
reacts with an incyanate group in which (A)/(B) is in a molar ratio of 4/1 to 1/4 and (A)/(B) is 1.0 or more in weight ratio. 1. A photosensitive resin composition for printing plates, which is a compound derived from a compound having two or more active hydrogen groups in the molecule, an organic diisocyanate, and an alcoholic hydroxyl group-containing acrylate compound.