JP3508788B2 - Liquid photosensitive resin composition for forming relief - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid photosensitive resin for forming reliefs, and more particularly to a liquid photosensitive resin used in the production of flexographic printing plates, which is a liquid in which a tunnel phenomenon does not easily occur in relief during plate making. A photosensitive resin is provided.

[0002]

2. Description of the Related Art For flexographic printing such as corrugated board printing and film printing, a photosensitive resin plate has been used instead of a conventional rubber plate. In the production of such a photosensitive resin plate, (1) it is economical because it can collect and reuse the resin of the non-image area that does not become a relief, and (2) it can be developed with an aqueous cleaning solution. Liquid photosensitive resins, which are in a liquid state before light irradiation, are often used because of their excellent working environment. Such a liquid photosensitive resin is usually made into a desired printing plate through an image forming exposure step, a developing step, a post-exposure step and a drying step by a plate making device.

A liquid photosensitive resin used for flexographic printing is obtained from a liquid photosensitive resin through a plate making process, such as low viscosity, storage stability, good plate image reproducibility and good aqueous solution developability. It is required that the printing plates used have high impact resilience, high mechanical strength, ink resistance, and printing ink acceptance transferability. Particularly, one of the important performances required for a printing plate for corrugated board printing is repulsion elasticity, and higher repulsion elasticity is required.

Since the mechanical properties are easily balanced and the light resistance is excellent, a liquid photosensitive material based on a polyester polyether polyurethane prepolymer having an ethylene type addition-polymerizable unsaturated group at both ends is used. Resins (see, for example, Japanese Patent Publication No. 52-7761 and Japanese Patent Laid-Open No. 4-95959) are often used.

However, when a printing plate is prepared using a liquid photosensitive resin based on the polyester polyether polyurethane prepolymer, (1) the recovery ratio of the uncured recovery resin is increased, and (2) the weight of the plate is reduced. In addition, (3) the relief depth is increased in order to eliminate the risk of background stains on the printed matter. In that case,
In particular, in a relatively thin linear relief (line width 100 to 500 μm) in which both ends are connected to the same solid relief and the whole is within the vicinity of the solid relief (within 1 cm), the intermediate position in the vertical direction of the relief or An abnormal phenomenon in which a through hole occurs near the bottom (floor forming layer (back layer)), that is, a tunnel phenomenon may occur (see FIG. 1). When the relief depth is around 1.5 mm or more, the tunnel phenomenon tends to occur, and when the relief depth is around 2.0 mm or more, the tunnel phenomenon occurs more frequently, which causes practical problems as described later. Come on.

FIG. 1 is a plan view and a sectional view showing an example of a printing plate having a relief in which a tunnel phenomenon occurs.
Shown is a solid relief 1 and a fine linear relief 2 with both ends bound to 1 and generally in the vicinity of the solid relief. A through hole 3 is formed in 2 due to a tunnel phenomenon. 4 is a normal thin linear relief, 5 is a support,
6 is a floor part forming layer (back layer). Moreover, 7 has shown the relief depth. If a printing plate in which such a tunnel phenomenon occurs is used for printing as it is, the printing pressure is not sufficiently applied to the relief having the through holes, and thus the ink acceptability and transferability become insufficient, or during printing. There arises a problem that the relief portion is missing.

In order to suppress the occurrence of such a tunnel phenomenon, it is sufficient to lengthen the exposure time for image formation, but this method causes overexposure of a dark portion (shadow portion) of a screen, a blank image or a complicated character. However, there arises a problem that a blank image line is filled in, a character is thickened, and the plate image quality is deteriorated.

Further, a method has been proposed in which a liquid photosensitive resin based on such a polyester polyether polyurethane prepolymer contains a specific unsaturated amine compound to suppress the tunnel phenomenon (Japanese Patent Laid-Open No. 3-157).
No. 657), the tunnel phenomenon can be suppressed by this method, but an amine odor is generated to a considerable extent, and the work environment is deteriorated when the plate making work is performed in a workplace where ventilation equipment is insufficient. In addition, the addition of the unsaturated amine compound promotes a decrease in viscosity of the liquid photosensitive resin during storage, which may cause problems such as difficulty in maintaining plate thickness accuracy in the plate making process. there were.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the drawbacks of the liquid photosensitive resin based on the conventional polyester polyether polyurethane prepolymer as described above, that is, a tunnel phenomenon occurs in relief during plate making. It is to provide a liquid photosensitive resin that is less likely to generate.

[0010]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that they have an ethylenic addition-polymerizable unsaturated group at both ends, and have a polyester segment and a polyether segment. In the unsaturated polyurethane prepolymer consisting of, it has been found that the above problem can be solved when the weight ratio of the polyester segment and the polyether segment is within a predetermined range and the polyester segment contains a specific structural unit. The present invention has been completed based on the above.

That is, the present invention comprises (A) a plurality of diol segments linked via urethane bonds, having an ethylene type addition-polymerizable unsaturated group at both ends, and the plurality of diol segments are at least 1 100 parts by weight of an unsaturated polyurethane prepolymer consisting of one polyester diol segment and at least one polyether diol segment, and (B) an ethylenically unsaturated addition-polymerizable monomer 5 to 20
0 parts by weight, and (C) 0.0 relative to the total weight of component (A) and component (B)
In the liquid photosensitive resin composition comprising 1 to 10% by weight of a photopolymerization initiator, the weight ratio of at least one polyester diol segment to at least one polyether diol segment of the prepolymer is 1: 3 to.
Within the range of 4: 1 and each of the at least one polyester diol segment has the formula (1)

[0012]

[Chemical 3] (Wherein, R represents a divalent aliphatic group or a divalent aromatic group) relief, which is a polyester diol segmenting preparative consisting repeating units of units represented by
A liquid photosensitive resin composition for forming a structure is provided.
It

The present invention will be described in detail below. The unsaturated polyurethane prepolymer used in the present invention has a structure in which a polyester segment and a polyether segment are linked via a urethane bond, and an ethylene type addition polymerizable unsaturated group is introduced at both ends thereof. There is something. In the present invention, the polyester segment contains a structural unit represented by the formula (1) as a diol-based unit.

A polyester segment containing a structural unit represented by the formula (1) as a diol-based unit is obtained by condensation polymerization of a diol mainly containing 3-methyl-1,5-pentanediol and a dicarboxylic acid. The resulting polyester segment.

The liquid photosensitive of the present invention based on unsaturated polyurethane prepolymer having a polyester <br/> segment containing the structural unit represented by the units based on such diol formula (1) When the resin composition is used to make a plate, the relief does not easily cause a tunnel phenomenon. At the same time, the printing plates obtained have improved durability.

Further, the liquid photosensitive resin composition of the present invention is
Performance by having a structure unit of which is expressed as a unit based on a diol polyester segment by the formula (1), low viscosity to be provided as a liquid photosensitive resin for flexographic printing plate production, such as storage stability In addition, the properties such as mechanical properties, ink resistance, and printing ink receiving and transferability that the flexographic printing plate should have are not impaired.

The diol constituting the polyester segment obtained by condensation polymerization may contain a diol other than 3-methyl-1,5-pentanediol within a range not impairing the intended purpose and effect of the present invention. However, in order to further exert the effect of the present invention, 3-methyl-1,5-
It is desirable to have as much pentanediol as possible. As diols other than 3-methyl-1,5-pentanediol, low-molecular diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol and diethylene glycol, Examples include high molecular weight polyether diols such as polyoxyethylene glycol and polyoxypropylene glycol. Further, depending on the purpose, a small amount of polyhydric alcohol such as trimethylolpropane, glycerin, pentaerythritol and the like may be used in combination with the diol.

As the dicarboxylic acid which constitutes the polyester segment obtained by condensation polymerization, known ones can be used. For example, succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, maleic acid, terephthalic acid, 1 , 5-naphthalenedicarboxylic acid and the like. More preferably adipic acid, azelaic acid,
It is sebacic acid.

Known polyether diols for providing the polyether segment of the unsaturated polyurethane prepolymer of the present invention are known, for example, polyoxyethylene glycol (PEG), polyoxypropylene glycol (PP).
G), polyoxyethylene-oxypropylene random or block copolymer diol, polyoxytetramethylene glycol (PTMG), polyoxyethylene-
Oxytetramethylene random or block copolymer diol, polyoxypropylene-oxytetramethylene random or block copolymer diol and the like are used. Among them, the polyether segment has the formula ( 3 )

[0020]

[Chemical 4] By containing 5% by weight or more of the oxyethylene group represented by the above with respect to the unsaturated polyurethane prepolymer, good uncured resin washability can be obtained in the developing step. However, when it exceeds 40% by weight, the alcohol / water-based ink resistance required for the flexographic printing plate is deteriorated, so 40% by weight or less is preferable. A more preferable range is 7
~ 30% by weight.

Specific examples of the polyether diol giving the polyether segment containing the oxyethylene group represented by the formula ( 3 ) include polyoxyethylene glycol, polyoxyethylene-oxypropylene random or block copolymer. Polymer diols, polyoxyethylene-oxytetramethylene random or block copolymer diols and the like can be mentioned.

The ratio of polyester segment to polyether segment of the unsaturated polyurethane prepolymer of the present invention is in the range of 1: 3 to 4: 1 by weight. Within this range, the tunnel phenomenon is unlikely to occur in the relief during plate making, and the durability of the printing plate obtained through the plate making process becomes excellent. Further, a plate having high mechanical strength required for flexographic printing is obtained, and the plate has excellent light resistance. Further, the uncured resin developability in the developing step during plate making is also good. If the weight ratio is less than 1: 3, it becomes difficult to obtain a plate having high mechanical strength, and the light resistance of the plate also deteriorates. On the other hand, if the weight ratio is greater than 4: 1, the developability of the uncured resin is lowered. A more preferable ratio is 1: 2 by weight.
Within the range of 3: 1.

The size of the polyester segment and the polyether segment is usually a number average in view of the ease of controlling the urethane reaction and the balance between the viscosity of the liquid photosensitive resin obtained and the mechanical properties of the plate obtained therefrom. Those having a molecular weight of 500 to 5,000 are used. The number average molecular weight referred to here is a polystyrene equivalent number average molecular weight measured by the GPC method.

The unsaturated polyurethane prepolymer of the present invention has a structure in which the polyester segment and the polyether segment are linked through urethane bonds. The diisocyanate used for this linking is an isocyanate. A known aromatic, aliphatic or alicyclic diisocyanate having two groups is used.

For example, 4,4'-diphenylmethane diisocyanate (MDI), p-phenylene diisocyanate, 2,4-tolylene diisocyanate (2,4-TD).
I), 2,6-TDI, 2,4-TDI / 2,6-TD
I mixture, 1,5-naphthalene diisocyanate (ND
I), tolidine diisocyanate (TODI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI) and the like. Among these diisocyanates, usually TDI, HMDI, I
PDI is preferably used. Further, when yellowing of the relief body formed is disliked, it is preferable to use a non-aromatic diisocyanate.

The unsaturated polyurethane prepolymer of the present invention has an ethylenic addition-polymerizable unsaturated group at both ends, but the method for introducing this unsaturated group is not particularly limited, and it can be selected from conventional methods. Any method can be selected from the above and used. For example, when the polyester segment and the polyether segment are linked by diisocyanate, both ends of the resulting prepolymer precursor are made into isocyanate groups, and a functional group having active hydrogen such as a hydroxyl group and an ethylene type By reacting a compound having an addition-polymerizable unsaturated group at the same time, an ethylene-type addition-polymerizable unsaturated group can be easily introduced into both ends of the prepolymer, or both ends of the prepolymer precursor are introduced. It is also possible to prepare a hydroxyl group, and to react this with a functional group capable of reacting with the hydroxyl group, for example, a carboxyl group, an isocyanate group, an epoxy group, and a compound having an ethylenic addition-polymerizable unsaturated group at the same time. An ethylenic addition-polymerizable unsaturated group can be introduced at both ends of the polymer.

As a compound having an active hydrogen-containing functional group such as a hydroxyl group used for introducing an ethylene-type addition-polymerizable unsaturated group and an ethylene-type addition-polymerizable unsaturated group at the same time (hereinafter referred to as unsaturated group-introducing compound) Is, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyoxypropylene glycol mono (meth) acrylate (molecular weight 3
00-1,000), polyoxyethylene glycol mono (meth) acrylate (molecular weight 300-1,000)
0), a 1: 1 addition reaction product of glycolic acid and glycidyl (meth) acrylate, a 1: 1 addition reaction product of glyceric acid and glycidyl (meth) acrylate, and glycerin di (meth) acrylate.

As the unsaturated polyurethane prepolymer of the present invention, those having a number average molecular weight of 5,000 to 30,000 are usually used. If the number average molecular weight is 5,000 or less, the Shore A hardness required for flexographic printing is 40.
A plate having softness before and after and sufficient tensile strength and elongation cannot be obtained, and when the number average molecular weight is 30,000 or more, the viscosity of the liquid photosensitive resin becomes too high and the handling during production or plate making becomes difficult. .

As the ethylene-type addition-polymerizable monomer used in the present invention, various known monomers can be used. The total amount of the ethylene-type addition-polymerizable monomer is 5 to 200 per 100 parts by weight of the unsaturated polyurethane prepolymer.
Within the range of parts by weight. If it is less than 5 parts by weight, the viscosity of the liquid photosensitive resin becomes high, and it becomes difficult to balance the hardness and the tensile strength and elongation of the obtained printing plate. On the other hand, if it exceeds 200 parts by weight, the curing shrinkage at the time of photocuring becomes large and the thickness accuracy of the obtained printing plate becomes poor, which is not preferable. Further, it becomes difficult to balance the hardness and the tensile strength and elongation of the obtained printing plate. From the viewpoint of workability in the plate making apparatus of the liquid photosensitive resin and the balance between hardness and tensile strength / elongation, the total amount of the ethylene-type addition-polymerizable monomer is within the range of 15 to 85 parts by weight per 100 parts by weight of the unsaturated polyurethane prepolymer. More preferably.

Examples of such ethylene-type addition-polymerizable monomers include unsaturated carboxylic acids such as acrylic acid and methacrylic acid or esters thereof (for example, alkyl-, cycloalkyl-, halogenated alkyl-, alkoxyalkyl-, hydroxyalkyl-). , Aminoalkyl-, tetrahydrofurfuryl-, allyl-, glycidyl-, benzyl-, phenoxy-acrylates and methacrylates;
Alkylene glycol or polyoxyalkylene glycol mono- or diacrylates and methacrylates; trimethylolpropane triacrylates and methacrylates; pentaerythritol tetraacrylates and methacrylates, etc., acrylamides, methacrylamides or their derivatives (for example N with alkyl or hydroxyalkyl groups). -Substituted or N, N'-substituted acrylamide and methacrylamide; diacetone acrylamide and methacrylamide; N, N'-alkylenebisacrylamide and methacrylamide, etc., allyl compounds (eg allyl alcohol, allyl isocyanate, diallyl phthalate, Triallyl cyanurate, etc.), maleic acid, maleic anhydride, fumaric acid or their esters (eg alkyl, halo) Down alkyl, such as mono- or dimaleate and fumarates alkoxyalkyl), other unsaturated compounds (such as styrene, vinyl toluene,
Divinylbenzene, N-vinylcarbazole, N-vinylpyrrolidone, etc.). The ethylene-type addition-polymerizable monomers may be used alone or in combination of two or more.

Further, in flexographic corrugated board printing, a plate having higher impact resilience is required due to the problem of paper dust (chips of corrugated board) adhering to the plate during printing. From this viewpoint, ethylene type addition polymerization Formula ( 2 )

[0032]

[Chemical 5] It is preferable to contain the acrylic monomer represented by the following in the range of 17 parts by weight to 65 parts by weight per 100 parts by weight of the unsaturated polyurethane prepolymer. If it is less than 17 parts by weight, a significant improvement in impact resilience cannot be achieved. Further, if it exceeds 65 parts by weight, the reproducibility and mechanical strength of the plate are deteriorated.

In the formula ( 2 ), n represents the number of repeating oxyethylene groups and is within the range of 1 to 20. The larger the number of n, the higher the impact resilience. But n
When the value becomes larger, the viscosity-reducing effect (dilution effect) of the liquid resin, which is one of the roles as a monomer, becomes weaker and the flexographic water-based ink resistance of the printing plate decreases, so from this viewpoint, n should not exceed 20. Is good. From the balance of impact resilience, dilution effect and ink resistance, n is preferably in the range of 2 to 10.

R is an alkyl group having 2 to 22 carbon atoms.
The alkyl group may be linear or branched. Examples of such an alkyl group include an ethyl group, a propyl group, a butyl group, a pentyl group, an octyl group, an isooctyl group, a decyl group, an isodecyl group and a 2-ethylhexyl group. When the alkyl group is a methyl group having 1 carbon atom, the printing plate obtained has low resistance to water-based inks, which is not preferable. When the number of carbon atoms of the alkyl group exceeds 22, the diluting effect on the liquid resin becomes low, which is not preferable. More preferably, the range of 2-14 is good.

Specific examples of the acrylic monomer represented by the formula ( 2 ) include ethylene glycol ethyl ether acrylate, ethylene glycol butyl ether acrylate, diethylene glycol-2-ethylhexyl ether acrylate, nanoethylene glycol lauryl ether acrylate and triethylene glycol hexyl. Examples thereof include ether acrylate. These may be used alone or in combination of two or more.

The impact resilience is measured by the falling ball method at a temperature of 20.
At 7 ° C, an iron ball with a diameter of 8 mm was dropped naturally from a height of 30 cm above the sample plate having a thickness of 7 mm, and the height x cm at which the iron ball bounces was measured, and the impact resilience (%) = 100 (x /
30). At this time, if the sample surface is sticky, the measured value will change accordingly.
Measure the surface after powdering it with talc.

As the photopolymerization initiator used in the present invention, any one of conventionally known compounds can be selected and used. Examples of such a photopolymerization initiator include benzoin, benzoin ethyl ether, benzoin-n-propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and other benzoin alkyl ethers, 2,2-dimethoxy-2-phenylacetophenone, and the like. Benzophenone, benzyl, diacetyl, diphenyl sulfide, eosin, thionine,
Examples thereof include 9,10-anthraquinone and 2-ethyl-9,10-anthraquinone. These photopolymerization initiators may be used alone or in combination of two or more. The addition amount thereof is in the range of 0.01 to 10% by weight based on the total amount of the unsaturated polyurethane prepolymer and the ethylene-type addition-polymerizable monomer.

To the liquid photosensitive resin of the present invention, a thermal polymerization inhibitor, an ultraviolet absorber, a light stabilizer, a dye, a pigment, a lubricant, an inorganic filler, a surfactant, etc. may be added depending on the use or purpose. You can

A preferred example of the step of producing a relief printing plate using the liquid photosensitive resin of the present invention will be described.
1) Place a negative film on a glass plate that transmits actinic rays from a lower light source, cover with a thin protective film,
A liquid photosensitive resin of the present invention is poured on it, and a base film serving as a support is attached while squeegeeing it with a constant plate thickness, 2) a short exposure from the support side by an upper light source, Back exposure step of depositing a uniform thin resin layer, that is, floor part forming layer on the entire surface of the plate support side, 3) Relief forming exposure step of performing image forming exposure from the lower light source through the transparent part of the negative film, and 4) uncured resin. Development process to remove and wash 5) Letterpress printing by immersing the whole developed plate in water, irradiating with actinic rays to fully cure the incompletely cured area, and then drying it. Plates can be manufactured.

When the thickness of the curing plate is 4 mm or more, masking exposure for forming a base (shelf part) which is a basis of relief in advance by selectively exposing from the support side by an upper light source before the relief exposure step. It is desirable to do. In this case, for example, a relief printing plate can be manufactured by sequentially performing a molding step, a masking exposure step, a relief formation exposure step, a back exposure step, a development step, an underwater post-exposure step and a drying step.

Examples of the actinic ray source used for exposure in the plate making process include a high pressure mercury lamp, an ultrahigh pressure mercury lamp, an ultraviolet fluorescent lamp, a carbon arc lamp and a xenon lamp. Further, as a transparent image carrier used for forming a relief image, a negative or positive film for photolithography by a silver salt image is mainly used. Examples of the cleaning liquid for the uncured resin include water, an alkaline aqueous solution, and a surfactant aqueous solution.

The liquid photosensitive resin composition for forming a relief of the present invention is used for producing a flexographic printing plate, and is subjected to the same steps as those of the flexographic printing plate described above to obtain a stamp excellent in impression and transferability of ink. It can be used for direct plate making such as printing plates.

[0043]

The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

Production Example 1 Production of unsaturated polyurethane prepolymer A 0.13 mol of poly (3-methyl-1,5-pentanediol adipate) diol (hydroxyl value 37.40) and polyoxyethylene (EO) -oxypropylene (PO)
Block copolymer diol (EO / PO molar ratio 1/4,
Hydroxyl value 44.88) 0.48 mol and dibutyltin dilaurate (hereinafter abbreviated as BTL) 0.09 g as a catalyst
Was placed in a reaction vessel and mixed well. Tolylene diisocyanate (2,4-body / 2,6-body molar ratio 4/1,
0.72 mol (hereinafter abbreviated as TDI) is added, the mixture is stirred well, the external temperature is raised from 40 ° C. to 80 ° C., and the mixture is reacted for about 5 hours as it is, followed by poly (unsaturated group-introducing compound). 0.93 mol of oxypropylene) glycol monomethacrylate (molecular weight 380) was added and well stirred.

After reacting for about 2 hours, the reaction is stopped,
An unsaturated polyurethane prepolymer A was obtained. The unsaturated polyurethane prepolymer contains a stoichiometric excess of an unsaturated group-introducing compound. The number average molecular weight Mn of this unsaturated polyurethane prepolymer is the following GPC
The result of measurement by the method (* 1) was about 2.3 × 10 ⁴ . The weight ratio of the polyester segment (hereinafter referred to as polyester segment a) containing the structural unit represented by the formula (1) as a diol-based unit in the unsaturated polyurethane prepolymer to the polyether segment is determined by the following method. The result obtained in (* 2) was 1: 3.

(* 1) The conditions for measuring the polystyrene reduced number average molecular weight by the GPC method were as follows. (1) Column: polystyrene gel column TSK GE
Two L GMHXL (7.8 mm x 300 mm, manufactured by Tosoh Corporation). (2) Solvent: THF (without adding a small amount of water). (3) Flow rate: 1.0 ml / min. (4) Sample concentration: 0.4 to 0.5%. (5) Preparation of calibration curve: The concentration is about 1/2 of the sample concentration. (6) Effective number: Displayed in two digits.
(7) Detection group: RI (differential refractometer). (8) Standard polystyrene: number average molecular weight range is 5.00 × 10 ^{2 to} 1.2
6 × 10 ⁶ . (9) GPC device: High-speed GPC HLC-
8020 (manufactured by Tosoh Corporation).

(* 2) First, the following GPC is performed using GPC.
The unsaturated polyurethane prepolymer was separated and purified by removing the excess unsaturated group-introducing compound that exceeded the stoichiometric amount added during the production of the unsaturated polyurethane prepolymer. Next, about 35 mg of the purified unsaturated polyurethane prepolymer was dissolved in 1 ml of deuterated chloroform (containing 0.01% of tetramethylsilane), and ¹ % was dissolved under the following NMR conditions.
1 H-NMR analysis was performed. From the obtained ¹ H-NMR spectrum, the peaks derived from the respective components of the polyester segment, the polyether segment, the diisocyanate residue and the unsaturated group-introducing compound residue constituting the unsaturated polyurethane prepolymer were assigned. Then, the weight ratio of each component was calculated from the integrated value of each peak, and the ratio of the polyester segment and the polyether segment was calculated.

GPC conditions: (1) Apparatus: LC-08 manufactured by Nippon Analytical Industry Co., Ltd. (2) Column: 2H manufactured by JAIGEL
-1H. (3) Detector: UV (254 nm), RI (differential refractometer). (4) Flow rate: 3.3 ml / min. (5) Solvent:
Chloroform. NMR conditions: (1) Device: JNM-GX manufactured by JEOL Ltd.
400. (2) Observation frequency: 400 MHz. (3) Observation width: 4,000 Hz. (4) Pulse: 13.5 μse
c. (45 °) (5) Measuring method: SGNON (Singl
e pulles, Non-decoupling).

Comparative Production Example 1 Production of Unsaturated Polyurethane Prepolymer B 0.16 mol of poly (propylene glycol adipate) diol (hydroxyl value 44.88) and polyoxyethylene (EO) -oxypropylene (PO) block copolymer Diol (EO / PO molar ratio 1/4, hydroxyl value 44.8
8) 0.48 mol and 0.32 g of BTL as a catalyst were put in a reaction vessel and mixed well. After adding 0.75 mol of TDI thereto and stirring well, the external temperature was raised from 40 ° C to 80 ° C and reacted for about 5 hours, and then poly (oxypropylene) glycol as a compound for introducing an unsaturated group. 0.93 mol of monomethacrylate (molecular weight 380) was added and stirred well.

After reacting for about 2 hours, the reaction is stopped,
An unsaturated polyurethane prepolymer B was obtained. The unsaturated polyurethane prepolymer contains a stoichiometric excess of an unsaturated group-introducing compound. The number average molecular weight of this unsaturated polyurethane prepolymer was about 2.3 × 10 ⁴ as a result of measurement by the above-mentioned GPC method. The weight ratio of the polyester segment and the polyether segment in the unsaturated polyurethane prepolymer was 1: 3 as a result of the above method.

Production Example 2 Production of unsaturated polyurethane prepolymer C 0.27 mol of poly (3-methyl-1,5-pentanediol adipate) diol (hydroxyl value 37.40) and polyoxyethylene (EO) -oxypropylene (PO)
Block copolymer diol (EO / PO molar ratio 1/4,
Hydroxyl value 44.88) 0.32 mol and BTL as catalyst
0.07 g was put into a reaction vessel and mixed well. TD there
After adding 0.69 mol of I and stirring well, the external temperature is adjusted to 40
The temperature was raised from 80 ° C. to 80 ° C., and the reaction was continued for about 4 hours, then 0.93 mol of poly (oxypropylene) glycol monomethacrylate (molecular weight 380), which is an unsaturated group-introducing compound, was added and well stirred.

After reacting for about 2 hours, the reaction is stopped,
An unsaturated polyurethane prepolymer C was obtained. The unsaturated polyurethane prepolymer contains a stoichiometric excess of an unsaturated group-introducing compound. The number average molecular weight Mn of this unsaturated polyurethane prepolymer is the above-mentioned GPC.
As a result of measurement by the method, it was about 2.3 × 10 ⁴ . The weight ratio of the polyester segment a and the polyether segment in the unsaturated polyurethane prepolymer was 1: 1 as a result of the above method.

Comparative Preparation Example 2 Preparation of Unsaturated Polyurethane Prepolymer D 0.32 mol of poly (propylene glycol adipate) diol (hydroxyl value 44.88) and polyoxyethylene (EO) -oxypropylene (PO) block copolymer Diol (EO / PO molar ratio 1/4, hydroxyl value 44.8
8) 0.32 mol and 0.32 g of BTL as a catalyst were put in a reaction vessel and mixed well. After adding 0.75 mol of TDI thereto and stirring well, the external temperature was raised from 40 ° C to 80 ° C, and the reaction was continued for about 4 hours, and then poly (oxypropylene) glycol, which is an unsaturated group-introducing compound. 0.93 mol of monomethacrylate (molecular weight 380) was added and stirred well.

After reacting for about 2 hours, the reaction is stopped,
An unsaturated polyurethane prepolymer D was obtained. The unsaturated polyurethane prepolymer contains a stoichiometric excess of an unsaturated group-introducing compound. The number average molecular weight of this unsaturated polyurethane prepolymer was about 2.3 × 10 ⁴ as a result of measurement by the above-mentioned GPC method. The weight ratio of the polyester segment and the polyether segment in the unsaturated polyurethane prepolymer was 1: 1 as a result of the above method.

Examples 1-5 , Comparative Examples 1-2 As shown in Table 1 in the unsaturated polyurethane prepolymers A to D produced in the above production examples, ethylene-type addition-polymerizable monomers, photopolymerization initiators, and other additives Example 1,
5 , liquid photosensitive resin compositions of Comparative Examples 1 and 2 were obtained. The obtained composition was evaluated as follows.
The measurement was carried out at 20 ° C. unless otherwise specified.

(1) Tunnel measuring method: thin wire (line width 10
Both ends (0-500 μm) are bound to the same solid pattern,
Moreover, using a negative film containing a thin wire pattern (see FIG. 1) such that the entire thin wire is in the vicinity of the solid pattern (within 1 cm),
Asahi Kasei's APR plate-making device AF210E,
The back exposure from the upper light source and the relief formation exposure from the lower light source shown in Table 2 were applied, and the thickness (including the support) was 7 m.
m, relief depth 2.5 mm (floor formation layer (back layer)
A printing plate having a thickness of 4.5 mm and a support) was prepared. With respect to the printing plate prepared, the presence or absence of cavities (tunnels) generated in the middle of the relief or near the floor forming layer was observed.

(2) Tensile property retention rate: A spacer is sandwiched between two soda glass plates each having a thickness of 1 mm and covered with a thin protective film of the prepared liquid photosensitive resin composition so that the thickness becomes 1 mm. The light intensity on the glass plate is 2.0
Exposed for 30 minutes with a light source intensity of mW / cm ² and a thickness of 1 mm
I made a sample version of. JI using this sample version
Tensile physical properties were measured by a method based on SK6301 (hereinafter referred to as initial tensile physical properties). Then, the sample plate was left in a thermo-hygrostat set at 50 ° C. and 80% relative humidity for 1 month, taken out and allowed to stand at 20 ° C. for 1 day, and then the tensile properties were measured by the same method as described above (the following aging). Called tensile properties). The ratio of the tensile physical properties over time to the initial tensile physical properties was shown as a percentage, which was taken as the tensile physical property retention rate.

(3) Hardness retention rate: thickness (including support) having a solid image by the same method as the tunnel measurement method, 7 mm
A sample plate was prepared and the Shore A hardness was measured (hereinafter referred to as initial hardness). The measurement was performed with a Zwick automatic hardness meter (ASTM D2240), and a value 60 seconds after the start of measurement was obtained using a load of 8 kg. Then, place the sample plate in a constant temperature and humidity chamber set at 50 ° C and 80% relative humidity.
After leaving it for a month, taking it out and leaving it to stand at 20 ° C. for 1 day, the Shore A hardness was measured by the same method as described above (hereinafter referred to as hardness over time). The ratio of the hardness over time to the initial hardness was shown as a percentage, which was taken as the hardness retention rate. The compositions of Examples 1 to 5 and Comparative Examples 1 and 2 were measured by the above method, and the results are summarized in Table 3.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

[Table 3]

[0062]

[Table 4]

[0063]

[Table 5]

While the compositions of Examples 1 to 5 did not show the occurrence of tunnels, the compositions of Comparative Examples 1 and 2 showed the occurrence of tunnels. Further, the compositions of Examples 1 to 5 have a tensile property retention of 97 to 100% and a hardness retention of 9
7 to 99%, while the compositions of Comparative Examples 1 and 2 had a tensile property retention of 78, 81% and a hardness retention of 80,
It was as low as 79%. Furthermore, the impact resilience of Examples 3 to 5 is
Examples 1 and 2 were 35% and 29 %, while 50
It was as high as ~ 58%.

[0065]

INDUSTRIAL APPLICABILITY The liquid photosensitive resin composition of the present invention is less likely to cause a tunnel phenomenon in the relief when the plate is made from the composition, and the printing plate obtained has improved durability. It is useful for making corrugated board.

[Brief description of drawings]

FIG. 1 is a plan view (A) and a sectional view (B) showing an example of a printing plate having a relief in which a tunnel phenomenon occurs.

[Explanation of symbols]

1 solid relief 2 1 thin linear relief with both ends bonded to 1 and the whole being in the vicinity of 1 3 through hole 4 generated by tunnel phenomenon normal fine linear relief 5 support 6 floor forming layer 7 Relief depth

Continuation of front page (56) Reference JP-A-4-95959 (JP, A) JP-A-3-157657 (JP, A) JP-A-63-90526 (JP, A) JP-A-54-93096 (JP , A) JP-A-4-68014 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03F ^7/ 00-7/18

Claims (2)

(57) [Claims] 1. (A) A polyester diol segment comprising a plurality of diol segments linked via urethane bonds, having an ethylenic addition-polymerizable unsaturated group at both ends, and the plurality of diol segments being at least one polyester diol segment. 100 parts by weight of an unsaturated polyurethane prepolymer comprising at least one polyether diol segment, and (B) an ethylenically unsaturated addition-polymerizable monomer 5 to 20
0 parts by weight, and (C) 0.0 relative to the total weight of component (A) and component (B)
In the liquid photosensitive resin composition comprising 1 to 10% by weight of a photopolymerization initiator, the weight ratio of at least one polyester diol segment to at least one polyether diol segment of the prepolymer is 1: 3 to.
Within the range of 4: 1 and each of the at least one polyester diol segment has the formula (1) (Wherein, R represents a divalent aliphatic group or a divalent represents an aromatic group) polyester diol segmenting preparative relief structure forming liquid photosensitive, which is a formed of recurring units of a unit represented by Resin composition. 2. An ethylenically unsaturated addition-polymerizable monomer is represented by the following formula ( 2 ): (However, R represents a linear or branched alkyl group having 2 to 22 carbon atoms, and n represents an integer in the range of 1 to 20.)
The acrylate monomer represented by the formula (1) is contained, and the amount of the acrylate monomer is in the range of 17 parts by weight to 65 parts by weight per 100 parts by weight of the polyurethane prepolymer as the component (A). A liquid photosensitive resin composition for forming a relief structure.