JPH045179B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved photopolymerizable composition, and more particularly to a photopolymerizable composition that is cured by actinic rays and has excellent relief-forming properties. In recent years, in the field of letterpress printing, photopolymerizable compositions, that is, photosensitive resin compositions, which can be easily and quickly plate-made by light irradiation, have been gaining momentum in place of rubber plates, paper-type lead plates, metal letterpress plates, etc. As photopolymerizable compositions have begun to be used, various types of photopolymerizable compositions have been put on the market. These photopolymerizable compositions are classified into liquid types and solid types depending on their state before exposure, and both of them are composed of a polymer component containing or not containing an addition-polymerizable unsaturated group and an addition-polymerizable unsaturated group. It contains a monomer as an essential component, and generally further contains a photopolymerization initiator, a photopolymerization sensitizer, a thermal polymerization inhibitor, etc. When this photopolymerizable composition is irradiated with actinic rays, it is cured and becomes insoluble in a developer and the like. This is because the addition-polymerizable unsaturated groups in the composition undergo a duplication or chain reaction to form a two-dimensional network structure, regardless of the type described above. Therefore, as a natural result, the part that is cured by being irradiated with light undergoes volumetric shrinkage, and the degree of shrinkage is usually controlled by the concentration of addition polymerizable unsaturated groups and the type of the unsaturated groups, and in particular the unsaturated groups. This is noticeable in liquid types with a relatively high concentration of saturated groups. Due to curing shrinkage of such a photopolymerizable composition,
This effect appears during image-forming exposure or post-exposure, which creates a problem in that it is difficult to produce a normal printing plate depending on the image. For example, if the plate thickness locally decreases by several tens of microns in a specific image area, if a tunnel-like cavity occurs in the middle of the relief shape, or if the cured area is large after post-exposure, the resin layer side will be extremely affected. Curling may occur. Among these problems, curling can be solved by lowering the concentration of addition-polymerizable unsaturated groups to an extent that does not impair the necessary physical properties, increasing the thickness of the support, or using a metal support. This problem has been dealt with by increasing the rigidity of the support. In addition, countermeasures have been taken to address the first two phenomena, such as reducing the relief depth and increasing the exposure light source intensity, but there are limits to their implementation due to printing conditions and exposure equipment costs. There has been a strong desire for a solution using the photopolymerizable composition itself. The inventors of the present invention have conducted intensive research to solve these problems in printing plate production, and have surprisingly found that by using a specific ethylenic addition-polymerizable monomer and an aromatic amino compound in combination, The inventors have discovered that the object can be achieved, and have completed the present invention based on this knowledge. That is, the present invention provides (A) a prepolymer, and (B) a polycyclic residue in which two or more rings each having 5 or more ring atoms are bonded to each other using at least one carbon atom as a common ring atom. an addition-polymerizable ethylenic monomer, (C) a photopolymerization initiator, and (D) a general formula (In the formula, R ₁ is an alkyl group having 1 to 5 carbon atoms, R ₂ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, X ₁ is a hydrogen atom, a hydroxyl group, or an alkyl group having 1 to 10 carbon atoms, X ₂ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. The prepolymer used as component (A) in the composition of the present invention may be either a polymer containing a photosensitive group in the molecule or a polymer not containing a photosensitive group, depending on the use or the form of the photopolymerizable composition. be selected as appropriate. For example, if the polymer is in solid form before irradiation with light, it does not need to contain photosensitive groups, but the polymer molecular weight should be 50,000 to 10
It is convenient to set it in the range of 1,000,000 from the viewpoint of ease of processing and development. On the other hand, if the form before light irradiation is liquid, it is generally preferable to use a photosensitive group-containing type from the viewpoint of mechanical properties of the cured product, and a polymer molecular weight in the range of 1000 to 30000 is practical from the viewpoint of viscosity adjustment. It is. The effects of the present invention are most evident when a photosensitive group-containing polymer having a molecular weight in the range of 1,000 to 30,000 is used as the prepolymer. This photosensitive group-containing polymer has CH ₂ =C in the molecule.
or -CH=CH- groups, such as polyvinyl cinnamate, cinnamate ester of ethylene-vinyl alcohol copolymer, styrene-maleic anhydride. Photodimerization-reactive copolymers such as cinnamic acid ester, polyvinylcinnamylidene acetate, polyvinylbenzalacetophenone, and polyvinylstyrylpyridium, or non-copolymers such as fumaric acid, itaconic acid, citraconic acid, and maleic acid. Saturated dibasic acid residue, or acryloyl group, methacryloyl group, acrylamide group, methacrylamide group, allyl group, vinyl ether group,
Examples include unsaturated polyesters containing vinylthioether groups, vinylamino groups, etc., unsaturated polyurethanes, and unsaturated polyamides. On the other hand, as polymers that do not contain photosensitive groups,
Examples include alcohol-soluble polyamides, polyvinyl alcohol, and cellulose derivatives such as cellulose and cellulose acetate. Among the above-mentioned polymers, the effects of the present invention are particularly noticeable in unsaturated dibasic acid residues such as fumaric acid, itaconic acid, citraconic acid, and maleic acid, or acryloyl groups, methacryloyl groups, acrylamide groups, This is a case where unsaturated polyester, unsaturated polyurethane, or unsaturated polyamide containing methacrylamide groups is used as a prepolymer. Component (B) used in the composition of the present invention is an addition-polymerizable ethylenic monomer having a spiro-type or fused-type polycyclic organic group having 5 or more ring atoms. The ethylenically unsaturated group present in this molecule is an unsaturated group having a carbon-carbon double bond without significant steric hindrance that can undergo a crosslinking reaction by chain polymerization or dimerization reaction, such as CH ₂ =CH-, _CH2 =C, -CH=CH-. These unsaturated groups are appropriately selected depending on the type of photosensitive group in the prepolymer used together. For example, if the photosensitive group in the prepolymer is of the cinnamoyl type, it is preferable that the unsaturated group of the monomer is also of the cinnamoyl type. In addition, when the prepolymer does not contain such a dimerization reaction type photosensitive group, the unsaturated group of the monomer is generally a CH ₂ =CH-CO- group or a CH ₂ =C
Groups such as (CH ₃ )-CO- are advantageous because they have high copolymerization reactivity. Next, the polycyclic residue present in the monomer is a polycyclic carbocyclic ring in which each ring has 5 or more ring atoms and at least one carbon atom is bonded as a common ring atom. It is a heterocyclic group, and the ring may have a fused structure or a spiro structure. Examples of such rings include, for example, bicyclo[2,1,0]pentane ring, bicyclo[5,4,2]undecane ring,
Bicyclo[3,2,1]octane ring, pinane ring,
Norpinane ring, bornane ring, norbornane ring, isobornane ring, Calan ring, 2-oxobornane ring, α-pinene ring, tricyclo[5,2,1,
0 ^2,6 ] Decene ring, 7-azabicyclo[2,2,1]
Heptane ring, quinuclidine ring, spiro[5,5]
undecane ring, adamantane ring, 2, 4, 8, 10
-tetraoxaspiro[5,5]undecane ring,
Spiro[2,2] pentane ring, Spiro[2,4]
Examples include carbocycles and heterocycles such as heptane rings. Among these, bridged carbocycles, heterocycles, or spirocycles are preferred because they are sterically bulky. Note that the number of atoms constituting the ring must be 5 or more; if the number of atoms is 4 or less, the ring is unreasonably strained, making it unstable and impractical for practical use. Further, even when the number of atoms is 5 or more, it is preferable to introduce a substituent such as a phenyl group into the ring as appropriate for imparting stability. The above polycyclic residue is introduced into the monomer by
For example, after introducing a hydroxyl group into the ring, this can be reacted with an unsaturated acid monomer such as cinnamic acid, acrylic acid, methacrylic acid, fumaric acid, or by adding several moles of ethylene oxide or propylene oxide to the hydroxyl group. The reaction can be carried out by the method of reacting the remaining hydroxyl group of the polyoxyalkylene glycol monoether with the unsaturated acid described above. The length of the connecting portion between the unsaturated group and the polycyclic residue in this monomer is preferably such that the number of atoms constituting the main chain is about 20 or less. Although the mechanism of the effect based on the monomer in the present invention is not clear, it is thought that the monomer has a ring structure and is sterically bulky. The amount of the monomer used as component (B) is preferably 5% by weight or more, more preferably 10% by weight or more, based on the sum of components (A) and (B). Specific examples of the monomer of component (B) used in the composition of the present invention include isobornyl acrylate or methacrylate, norbornyl acrylate or methacrylate, dicyclopentenoxyethyl acrylate or methacrylate, dicyclopentenoxypropyl acrylate or acrylic or methacrylic esters of diethylene glycol dicyclopentenyl monoether, such as methacrylate, acrylic or methacrylic esters of polyoxyethylene or polypropylene glycol dicyclopentenyl monoether, dicyclopentenyl cinnamate, dicyclopentenoxy 3,9-bis(1,1-bismethyl-2-oxyethyl)-spiro[5,5]undecane, 3,9-bis(1, 1-bismethyl-2-
oxyethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane, 3,9-bis(2
-oxyethyl)-spiro[5,5]undecane,
3,9-bis(2-oxyethyl)-2,4,8,
Mono-, diacrylate or mono-, dimethacrylate such as 10-tetraoxaspiro[5,5]undecane, or mono-, diacrylate or mono- of ethylene oxide or propylene oxide addition polymer of these spiroglycols, dimethacrylate, or the methyl ether of the monoacrylate or methacrylate,
1-azabicyclo[2,2,2]-3-octenyl acrylate or methacrylate, bicyclo[2,2,1]-5-heptene-2,3-dicarboxyl monoallyl ester, dicyclopentadienyl acrylate or Methacrylate, dicyclopentadienyloxyethyl acrylate or methacrylate, dihydrodicyclopentadienyl acrylate or methacrylate, etc. can be mentioned. Among these monomers, the following general formula is particularly preferred from the viewpoint of effectiveness and ease of obtaining raw materials. [In the formula, R ₃ is a hydrogen atom or a methyl group, R ₄ is

[Formula] (where R ₃ has the same meaning as above), n is an integer from 1 to 5] or [In the formula, R ₅ is a hydrogen atom or a methyl group, R ₆ is

[Formula] (where R ₅ has the same meaning as above), R ₇ is −CH ₂ − or

[Formula] X ₃ is a hydroxyl group, an alkoxy group having 1 to 3 carbon atoms, or

Monomers represented by the formula: (R ₅ has the same meaning as above), n is an integer from 1 to 5 are preferred. In the composition of the present invention, in addition to the component (B),
From the viewpoint of adjusting various physical properties of the composition, ordinary ethylenic addition polymerizable monomers can be used in combination, if necessary. Examples of such monomers include acrylamide or methacrylamide, N-methylol acrylamide or methacrylamide, N-diacetone acrylamide or methacrylamide,
N,N'-methylenebisacrylamide or methacrylamide, styrene, acrylonitrile, vinyl acetate, N-vinylpyrrolidone, N-vinylcarbazole, diallyl phthalate, diallyl isophthalate, diallyl maleate, diallyl chlorendate, diallyl adipate, triaryl lucyanurate, acrylic acid, methacrylic acid, or their esters (excluding monomers with specific ring structures that fall under component (B)), such as alkyl, cycloalkyl, tetrahydrofurfuryl, allyl, glycidyl, and hydroxyalkyl. Acrylates and methacrylates, alkylene glycols, mono- or di-acrylates and methacrylates of polyoxyalkylene glycols, mono-, di- or tri-acrylates and methacrylates of trimethylolpropane, mono-, di-, tri- or tetra-acrylates and methacrylates of pentaerythritol, etc., acetic acid. Addition polymerizable unsaturated monomers such as vinyl, itaconic acid, fumaric acid, maleic anhydride, maleic acid and mono- and dialkyl esters of these acids, unsaturated polyester and alkyd resins, unsaturated polyurethane resins,
Examples include polyurethane resins modified with addition polymerizable monomers having active hydrogen such as hydroxyacrylate or methacrylate. When an ethylenic addition polymerizable monomer other than component (B) is used in combination, the amount used is preferably 60% by weight or less based on the sum of the monomer and component (B). When the amount exceeds 60% by weight, the effect of the present invention decreases. In addition, component (B) and monomers other than component (B) are (A)
It is desirable to use such a proportion that the sum of these components is in the range of 10 to 100 parts by weight per 100 parts by weight of the components, and more preferably in the range of 30 to 70 parts by weight from the viewpoint of controlling the physical properties of the plate. As the photopolymerization initiator for component (C) in the composition of the present invention, known photopolymerization initiators may be used alone or in combination. As this photopolymerization initiator, for example, the general formula (R ₈ in the formula is a hydrogen atom or a linear or branched alkyl group having 1 to 8 carbon atoms, R ₉ is a hydrogen atom or -
_benzoin , its derivatives, benzyl,
diketones such as diacetyl and anthraquinone,
general formula (R ₁₀ in the formula is an alkyl group having 1 to 5 carbon atoms or

[Formula] R ₁₁ is an alkyl group having 1 to 5 carbon atoms, a halogen atom such as F, Cl, Br, I, a nitro group,

Examples include benzoyl compounds such as acetophenone and benzophenone, diphenyl sulfide, eosin, thionin, etc. represented by the formula -OR ₁₂ , R ₁₂ and R ₁₃ are hydrogen atoms and alkyl groups having 1 to 5 carbon atoms. be able to. These photopolymerization initiators can be used in an amount of 0.001 to 10% by weight based on the total amount of the prepolymer and the crosslinking agent monomer. Amounts in the range of 0.1 to 5% by weight are commonly used to obtain suitable photospeeds. Component (D) used in the composition of the present invention has the following general formula: (In the formula, R ₁ is an alkyl group having 1 to 5 carbon atoms, R ₂ is an alkyl group having 1 to 5 carbon atoms or a hydrogen atom, X ₁ is a hydrogen atom, a hydroxyl group, or an alkoxy group having 1 to 10 carbon atoms, X ₂ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms), such as p-(N,N- dimethylamino)benzaldehyde, p-(N,N-
diethylamino)benzaldehyde, p-(N-
methylamino)benzaldehyde, p-(N-methyl-N-n-butylamino)benzaldehyde or the corresponding benzoic acid or alkyl ester of said benzoic acid, such as ethyl p-(N,N-dimethylamino)benzoate, p- (N,N-dimethylamino)benzoate-n-propyl, p-(N,N
-dimethylamino)isoamyl benzoate, p-
(N-methyl-N-isoamylamino)isoamyl benzoate, etc., and ortho forms of the above compounds,
One example is the meta body. Furthermore, when introducing a substituent other than a hydrogen atom as -X ₂ in the general formula (), an electron-donating group such as an alkyl group having 1 to 5 carbon atoms or an alkoxy group having 1 to 5 carbon atoms is preferable. In particular, a methyl group or a methoxy group is preferable because it has little steric hindrance and enhances the activity of the compound. Among these aromatic amino compounds, from the viewpoint of storage stability of the photopolymerizable composition, benzoic acid alkyl ester types and N,N-dialkylamino compounds are preferred. In addition, these aromatic amino compounds may be used alone or in a mixture of two or more, and the amount used is the sum of component (A) and component (B), or When using monomers other than component (B),
It is preferably in the range of 0.1 to 10% by weight based on the total amount added to the above amounts, and more preferably in the range of 0.5 to 5% by weight from the viewpoint of the effects of the present invention and cost. In addition, in place of component (D), an alkyl unsubstituted amino form, i.e.

If the formula (X ₁ has the same meaning as above) is used, the storage stability will be significantly lowered, and there will be no effect of the present invention, so the compound cannot be used as component (D) of the present invention. For the purpose of stably storing the photosensitive resin composition of the present invention, a known thermal polymerization inhibitor can be used. The thermal polymerization inhibitor can be added at the same time as mixing the components of the composition, but it may also be added to each component in advance before mixing the components. Thermal polymerization inhibitors that can be used in the present invention include hydroquinone, mono-tert-butylhydroquinone, benzoquinone, 2,5-diphenyl-
p-benzoquinone, picric acid, di-p-fluorophenylamine, p-methoxyphenol,
Examples include 2,6-di-tert-butyl-p-cresol. It is desirable that these thermal polymerization inhibitors prevent the thermal polymerization reaction (dark reaction) without affecting the photocrosslinking reaction.
Therefore, the amount of thermal polymerization inhibitor added is 0.005% of the total amount of prepolymer and crosslinking agent monomer.
A range of 5.0% by weight is desirable. For the purpose of appropriately adjusting the mechanical properties, water resistance, solvent resistance, etc. of the cured product, 0.01 to 100 parts by weight of various auxiliary additives are added to the photosensitive resin composition of the present invention per 100 parts by weight of the composition. can be used.
The term "auxiliary additive" as used herein means anything other than the essential components of components (A) to (D) above. Typical examples include dioctyl phthalate and process oil. The photosensitive resin composition of the present invention has a wavelength of 200 nm to
Conveniently, curing is done by actinic radiation at 700 nm. Therefore, active light sources used for the photosensitive resin composition of the present invention include carbon arc lamps, ultra-high pressure mercury lamps, low pressure mercury lamps, high pressure mercury lamps, xenon lamps, ultraviolet fluorescent lamps, halogen lamps, metal halide lamps, Sunlight is preferable. When the photosensitive resin composition of the present invention is exposed through a negative (or positive) film having transparent lines,
The exposed image area becomes an insoluble cured product in about 0.5 to 10 minutes. Non-image areas that are not exposed to light can be developed sufficiently with a surfactant aqueous solution or an alkaline aqueous solution, but trichlene, perchlorene, chlorocene, acetone,
It goes without saying that dissolution and removal development can also be carried out using organic solvents such as methyl ethyl ketone and ethyl acetate. After development, drying, and post-exposure,
Used as a printing version. A feature of the present invention is that component (B), a monomer having a specific ring structure, and component (D), a specific aromatic amino compound represented by general formula (), are used in combination with a prepolymer and a photopolymerization initiator. The point is to do so. Even if only component (D) is used in combination with a prepolymer and a photopolymerization initiator without using the monomer of component (B), the effects of the present invention will not be fully exhibited, and if only the monomer of component (B) is used, Even when used together with a prepolymer and a photopolymerization initiator, the effect of the present invention is small. That is, by using both the monomer of component (B) and the compound represented by the general formula () of component (D) together, a synergistic effect of these compounds is produced and the intended purpose is achieved. . Some of the component (B) monomers used in the present invention are already known in other fields. That is, it is used for the purpose of improving adhesion and forming a film with excellent surface hardness (Japanese Unexamined Patent Publication No. 57-87409), or obtaining a curable film with excellent flexibility, water resistance, and alkali resistance. It is well known in coating applications such as those used for various purposes (for example, JP-A No. 57-125209, JP-A No. 56-81529, JP-A No. 55-13795, etc.). However, as revealed in the present invention, the above-mentioned problems regarding relief forming applications are
Until now, it has not been known at all that the problem can be solved to the extent that there is no practical problem by using the compound represented by the general formula (). When a printing plate is manufactured using the photopolymerizable composition of the present invention, even if a negative film containing the above-mentioned specific image area is used, a tunnel-like cavity occurs in the middle of the relief, or a cavity surrounded by a solid area occurs. There is no phenomenon in which the relief height in the highlight area is locally reduced by several tens of microns, and a plate with normal relief can be obtained using normal exposure means. Therefore,
When a printing plate obtained using the composition of the present invention is used for printing, good printed matter can be obtained with appropriate printing pressure. The photopolymerizable composition of the present invention is suitable not only for printing purposes but also for forming reliefs, such as molds and molding molds, and is further suitable for use in fields such as ultraviolet curing paints and photoadhesives. Needless to say, it can also be provided. EXAMPLES Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way. Synthesis Example 1 Polyethylene adipate (diol, n=
2500), 240 g of polypropylene glycol (diol, n=2400), and toluylene diisocyanate (hereinafter abbreviated as TDI, 2,4 body/
After mixing 52.3 g of 2,6 bodies = 3/2) and reacting at 70℃ for 3 hours with stirring, 30 g of 2-hydroxyethyl methacrylate and hydroquinone
0.1g and dibutyltin dilaurate (hereinafter BTL
0.1 g of the mixture was added and reacted at 80° C. under a dry air atmosphere until almost no characteristic absorption of NCO was observed on an infrared chart. This reaction product is referred to as prepolymer A. Synthesis example 2 Propylene glycol, ethylene glycol,
Molar ratio of fumaric acid, itaconic acid, and adipic acid
Condensation was carried out at a ratio of 0.3/0.2/0.1/0.1/0.3 to obtain an unsaturated polyester (acid value: 20 mgKOH/g).
This material is referred to as prepolymer B. Synthesis Example 3 Polypropylene adipate (diol, n=
3000) 300g and polylene glycol (diol,
200 g of Mn=2000), 41.8 g of TDI, and 0.1 g of BTL were mixed and reacted in the same manner as in Synthesis Example 1. Then, 20 g (0.1 mol) of a one-to-one adduct of glycidyl methacrylate and glycolic acid was mixed with 0.1 g of hydroquinone.
The reaction was carried out on an infrared chart until the absorption of NCO disappeared. Then succinic anhydride 10
g was added thereto, and the mixture was reacted at 85°C for 4 hours. The carboxylation reaction rate determined by acid value measurement was 97%. The reaction product thus obtained is referred to as prepolymer C. Synthesis example 4 ε-caprolactone polyester (diol,
In a mixture of 150 g of Mn=500) and 25.4 g of polypropylene glycol (diol, n=950)
Add 72.6g of TDI and react at 80℃ for 4 hours with stirring, then glycerin monomethacrylate
A mixed solution of 33 g of hydroquinone, 0.1 g of hydroquinone, and 0.1 g of dibutyltin dilaurate was added, and the mixture was reacted on an infrared chart until the absorption of NCO almost disappeared. Next, 20 g of succinic anhydride was added, and the reaction was carried out at a reaction rate of 99% based on the hydroxyl equivalent to obtain a highly viscous reaction product. The reaction product thus obtained is referred to as prepolymer D. Example 1 For 100 g of prepolymer A, 20 g of dicyclopentenoxyethyl methacrylate, 15 g of tetraethylene glycol monomethyl ether methacrylate, polypropylene glycol (n = 400)
Dimethacrylate 15g, 2,2-dimethoxy-2
-Phenylacetophenone 2g, p-methoxyphenol 0.1g, p-(N,N-dimethylamino)
Dissolve and mix 1.5 g of benzoic acid isoamyl ester,
A photopolymerizable composition P-I was obtained. Next, apply polyurethane adhesive to a thickness of about 10μ on the adhesive side of a 100μ thick polyester sheet.
The above-mentioned photopolymerizable composition P-I was applied to a thickness of 1.0 mm, then covered with a 12 μm thick polypropylene film, and a negative film was placed on top of the film and adhered with a glass plate. The negative film has a negative
Image A has a 100 line/in, 92% flat mesh, a transparent area of 5 cm x 5 cm around the area including the flat screen area, and a 3 cm x 2 cm image surrounded by a thin transparent line with a line width of 80 μ.
There is a rectangle, and the total area of the rectangle is
It has 120 lines/in and a flat mesh image B corresponding to 95%. First, the opposite side of the negative film was irradiated with a chemical lamp (FL20BL manufactured by Toshiba) for 14 seconds from a distance of 10 cm, and then the same type of chemical lamp as above was used for 4 minutes of irradiation from a distance of 10 cm from the negative film side. The amount of light irradiated onto the negative film surface was 290 mJ/cm ² as determined from the light source intensity measured with an oak ultraviolet intensity meter UV-302A. After exposure, remove the glass plate, negative film, and polypropylene film, and apply a 0.3% by weight aqueous sodium carbonate solution at 40°C from a distance of 10 cm at a pressure of 0.8
When spray development was carried out at Kg/cm ² for 2 minutes, the composition in the uncured area was completely dissolved and removed. After washing with water and drying, the plate was post-exposed for 5 minutes using the chemical lamp described above to obtain a printing plate. The height of the image area of this plate, that is, the relief depth (hereinafter abbreviated as RD) was 0.5 mm. The relief of the thin enclosing line with a line width of 80 μ, which is image area B of this plate, was normal, and no tunnel-like cavity was generated in the middle. Furthermore, located in image area A
The difference in plate thickness between the flat screen portion equivalent to 8% and the surrounding solid portion at 100 lines/in, that is, the difference in relief height, was measured with a depth microscope and found to be 8μ. When this printing plate was printed using a letterpress proofing machine,
Even under the appropriate printing pressure, the flat halftone area at the center of the solid area in image area A did not fade, and a printed matter was obtained with clear printing. Examples 2-5 Prepolymer A obtained in Synthesis Examples 1-4
-D were used to prepare photopolymerizable compositions having the compositions shown in Table 1. These compositions were subjected to test plate making in the same manner as in Example 1, and the difference in plate thickness between the solid area and the net area was measured for the image area A. The results are shown in Table 1. It was found that the difference in plate thickness of the photopolymerizable compositions of the present invention was less than half that of conventional photopolymerizable compositions, and was 15μ or less, which did not cause any problems in printing, and the effects of the present invention were confirmed. . Comparative Examples 1 and 2 Using prepolymers B and D obtained in Synthesis Examples 2 and 4, photopolymerizable compositions having the compositions shown in Table 1 were prepared. These compositions were plate-made in the same manner as in Example 1, and the image area A was evaluated in the same manner as in Examples 1 to 5. The results are shown in Table 1. It was found that the difference in plate thickness between the solid area and the mesh area was as large as 30 μm or more compared to the composition of the present invention.

[Table] Examples 6 to 8 Prepolymers B and C obtained in Synthesis Examples 1 and 3, and alcohol-soluble polyamide (
n=50000), a photopolymerizable composition having the composition shown in Table 2 was prepared. These compositions were made into plates in the same manner as in Example 1, and the state of relief formation of thin lines surrounding the dots in the image area was observed, and the relief depth (abbreviated as RD _NT ) at which no tunnel-like cavities were formed in the relief was determined. I asked for it.
When determining this RD _NT , it was decided to change the exposure time from the support side to change the relief depth, and the plate thickness was always set constant. The results are shown in Table 2. As is clear from this table, all of the compositions of the present invention had an RD _NT of 0.7 mm or more, and it was found that printing plates with no practical problems could be obtained. Comparative Examples 3 and 4 Using prepolymer A obtained in Synthesis Example 1, a photopolymerizable composition having the composition shown in Table 2 was prepared. These compositions were subjected to test plate making in the same manner as in Example 1, and the image area B was evaluated in the same manner as in Examples 6 to 8. The results are shown in Table 2. As is clear from this table, when either the compound represented by the general formula (), which is one of the essential components of the present invention, or the component monomer (B) is not used, the RD _NT is 0.40 mm or less in both cases. I found out.

【table】

【table】

Claims (1)

[Claims] 1. (A) Prepolymer, (B) Polycyclic residue in which two or more rings each having 5 or more ring atoms are bonded to each other with at least one carbon atom in common. addition-polymerizable ethylenic monomer with groups (C)
Photopolymerization initiator and (D) general formula (In the formula, R ₁ is an alkyl group having 1 to 5 carbon atoms, R ₂ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, X ₁ is a hydrogen atom, a hydroxyl group, or an alkoxy group having 1 to 10 carbon atoms, X ₂ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms.