JP2897375B2 - Photopolymerizable composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a photopolymerizable composition.

In particular, the present invention relates to an improved photopolymerizable composition exhibiting high sensitivity to light in a long wavelength region.

[Prior Art] Conventionally, many image forming methods using a photopolymerization system are known. For example, to prepare a photopolymerizable composition comprising a compound containing an addition-polymerizable ethylenic double bond and a photopolymerization initiator, an organic polymer binder used as desired, and the like,
This photopolymerizable composition is applied on a support to prepare a photosensitive material provided with a layer of the photopolymerizable composition, and a desired image is image-exposed to polymerize and cure the exposed portion, and dissolve and remove the unexposed portion. A method of forming a cured relief image by performing, a method of forming an image by causing a change in adhesive strength due to light, and then peeling off a support, and the other property of toner adhesion by light of a photopolymerizable composition layer There is an image creation method using change. Conventionally, benzoin, benzoin alkyl ether, benzyl ketal, benzophenone, anthraquinone, benzyl, Michler's ketone, or the like has been used as a photopolymerization initiator of the photopolymerizable composition applied to these methods.

These photopolymerization initiators had a function of responding to short-wavelength light mainly in the ultraviolet region of 400 nm or less.

In recent years, with the development of image forming technology, there has been a strong demand for photopolymers having high sensitivity to light rays in the visible region. For example, the argon ion laser
The laser plate making method using a 488 nm oscillation beam is considered as one of the promising techniques in the future, and in response to this, a number of photopolymerization initiation systems in which the sensitivity range is extended to about 500 nm have been proposed. Furthermore, recently, research on photoinitiating systems corresponding to long-wavelength light exceeding 600 nm has been activated. One of those applied technologies is laser plate making using a He-Ne laser or a semiconductor laser, and the other is a full-color image duplication technology using a photopolymerization system.

The latter is described in the specification of Japanese Patent Publication No. 46-41346 in the past, and according to the specification, droplets containing photopolymerization initiators and color couplers corresponding to blue, green, and red light, respectively. Three layers each of the photopolymerizable composition dispersed in a gelatin film are applied to form a photosensitive layer. Then, a technique is disclosed in which, when a color image light beam is irradiated and processed with a color developing solution, an uncured portion is colored to obtain a full-color image. Further, an application technique in which this idea is combined with a pressure-sensitive coloring technique using microcapsules has been proposed. For example, the description is found in JP-A-62-143044.
According to the specification, microcapsules are filled with a photopolymerizable composition containing a photopolymerization initiator sensitive to each of the three color light rays and each leuco dye, and coated on a sheet. After exposing this to a color image light beam, the capsule in the uncured portion is pressure-ruptured and transferred onto a color-developing sheet to transfer the yellow, magenta, and cyan colors to obtain a full-color image.

[Problems to be solved by the invention]

One of the issues demanded in the above-described laser plate making and full-color image duplication techniques is to improve the sensitivity of light-sensitive materials to light having a long wavelength, particularly in the region exceeding 600 nm. In particular, appropriate spectral sensitivity is required for the dissolution stability of the toner and the full-color reproduction technique.
We previously proposed a photoinitiating system consisting of a combination of a squarylium dye and a specific triazine compound, but their dissolution stability and spectral sensitivity characteristics were not always sufficient. The present invention has been made as a result of repeated studies to improve these problems. Therefore, the object of the present invention is to
An object of the present invention is to provide a photoinitiating system which is highly sensitive to light having a long wavelength, particularly in the range of 600 to 700 nm, has excellent dissolution stability, and has good spectral sensitivity characteristics.

[Means for solving the problem]

We have found that these problems can be solved by a system combining a squarylium dye with a specific structure and an s-triazine compound.

That is, the gist of the present invention is to provide a photopolymerizable composition comprising an addition-polymerizable ethylenically unsaturated compound and a photopolymerization initiation system, wherein the photopolymerization initiation system has the following general formula (I) A squarylium dye represented by [In the formula, R ₁ and R ₂ each represent an alkyl group or an aryl group which may have a substituent, and ring A and ring B each represent a benzene ring or a naphthalene ring which may have a substituent. And (b) a photopolymerizable composition comprising an s-triazine compound having at least one methyl halide group.

 Hereinafter, the present invention will be described in detail.

In the photopolymerizable composition of the present invention, an addition-polymerizable compound having at least one ethylenically unsaturated double bond (hereinafter abbreviated as “ethylenic compound”), which is contained as a first essential component, refers to a photopolymerizable compound. When the active composition is irradiated with actinic rays, it is a compound having an ethylenically unsaturated double bond such as addition-cured and cured by the action of a photopolymerization initiation system as a second essential component, for example, The above-mentioned monomer having a double bond or a polymer having an ethylenically unsaturated double bond in a side chain or a main chain. In the present invention, the meaning of the monomer is a concept corresponding to a so-called polymer substance, and therefore includes not only monomers in a narrow sense but also dimers, trimers, and oligomers. is there.

Examples of the monomer having an ethylenically unsaturated bond include unsaturated carboxylic acids, esters thereof and monohydroxy compounds, esters of aliphatic polyhydroxy compounds and unsaturated carboxylic acids, and aromatic polyhydroxy compounds and unsaturated carboxylic acids. And esters obtained by an esterification reaction of an unsaturated carboxylic acid with a polyvalent carboxylic acid and a polyvalent hydroxy compound such as the above-mentioned aliphatic polyhydroxy compound and aromatic polyhydroxy compound.

The ester of the aliphatic polyhydroxy compound and the unsaturated carboxylic acid is not limited, but specific examples thereof include ethylene glycol diacrylate, triethylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, and pentaerythritol. Acrylates such as diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, and glycerol acrylate; Acid ester, itaconic acid ester also replaced with itaconate, There are maleic acid esters in which instead of the crotonic acid ester or maleate was replaced.

Examples of the ester of the aromatic polyhydroxy compound and the unsaturated carboxylic acid include hydroquinone diacrylate, hydroquinone dimethacrylate, resorcin diacrylate, resorcin dimethacrylate, and pyrogallol triacrylate.

The ester obtained by the esterification reaction between the unsaturated carboxylic acid and the polyhydric carboxylic acid and the polyhydric hydroxy compound is not necessarily a single substance, but typical examples include acrylic acid, phthalic acid and ethylene glycol. Condensates, condensates of acrylic acid, maleic acid and diethylene glycol, condensates of methacrylic acid, terephthalic acid and pentaerythritol, condensates of acrylic acid, adipic acid, butanediol and glycerin, and the like.

Other examples of the ethylenic compound used in the present invention include acrylamides such as ethylenebisacrylamide; allyl esters such as diallyl phthalate; and vinyl group-containing compounds such as divinyl phthalate.

The polymer having an ethylenically unsaturated bond in the main chain is, for example, a polyester obtained by a polycondensation reaction between an unsaturated divalent carboxylic acid and a dihydroxy compound, a polycondensation reaction between an unsaturated divalent carboxylic acid and a diamine. And the like. The polymer having an ethylenically unsaturated bond in the side chain includes a condensation polymer of a divalent carboxylic acid having an unsaturated bond in the side chain such as itaconic acid, propylidene succinic acid, ethylidene malonic acid and a dihydroxy or diamine compound. . In addition, a polymer having a functional group having a reactive activity such as a hydroxy group or a methyl halide group on a side chain,
For example, a polymer obtained by a polymer reaction between polyvinyl alcohol, poly (2-hydroxyethyl methacrylate), polyepichlorohydrin and the like and an unsaturated carboxylic acid such as acrylic acid, methacrylic acid and crotonic acid can also be suitably used.

Of the ethylenic compounds described above, monomers of acrylates or methacrylates can be particularly preferably used.

Next, the photopolymerization initiation system, which is the second essential component of the photopolymerizable composition of the present invention, will be described. The photopolymerization initiation system of the present invention is composed of a combination of two components, the first component of which is (a) a squarylium dye represented by the following general formula [I].

[In the formula, R ₁ and R ₂ represent an alkyl group or an aryl group which may have a substituent, and ring A and ring B each represent a benzene ring or a naphthalene ring which may have a substituent. Heretofore, few squarylium dyes have sufficient solubility in the photosensitive layer, and have a tendency to precipitate easily, and as a result, have a drawback that stable photosensitive characteristics are difficult to obtain. In addition, most of the squarylium dyes
It can be used as a sensitizer corresponding to a light beam of 00 nm, that is, red light, and can be used as a red-sensitive material for full-color image reproduction, but the spectral sensitivity characteristics were not always sufficient. This tendency is particularly remarkable in a red light-sensitive material that is compatible with long wavelengths, but the reason is that the red light-sensitive material is largely shifted to an undesired short wavelength side. For example, in the case of a red sensitive material, 500 to 600 nm
Undesired photosensitivity occurs in the region, and as a result, the color reproducibility is deteriorated. As a parameter for evaluating this spectral sensitivity characteristic, in the case of a red sensitive material, it can be evaluated by the magnitude of the ratio of the sensitivity corresponding to 650 nm to the sensitivity corresponding to 550 nm. In other words, the larger the value of this ratio, the better the spectral sensitivity characteristics and, consequently, the color reproducibility. Hereinafter, this value is abbreviated as a spectral sensitivity value.

It has been difficult to satisfy both the above-mentioned dissolution stability and spectral sensitivity characteristics of conventional squarylium dyes, but we have found that the dyes of the above general formula [I] have good characteristics. .

R ₁ and R _{2 in the} general formula are preferably an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-hexyl group, an n-octyl group, and an aryl group. For example, it is a phenyl group or a naphthyl group. These may further have a substituent, and the substituent used is preferably a phenyl group, a phenoxy group, a methoxy group, or an ethoxy group.

Ring A and ring B are a benzene ring and a naphthalene ring which may have a substituent, and preferred substituents include a methyl group,
Alkyl groups such as ethyl group; alkoxy groups such as methoxy and ethoxy groups; and halogen atoms such as chlorine and bromine are preferred.

Examples of suitable squarylium satisfying such conditions include the following compounds.
[] Is an abbreviation of a compound.

As described above, the squarylium dye used in the present invention is exemplified by a conventional method, for example, HESprenger, Angew.Ch.
em.internat Edit 6 553 (1967).

Next, the second component (b) constituting the photopolymerization initiation system of the present invention will be described.

Component (b) is an s-triazine derivative having at least one mono-, di-, or trihalogen-substituted methyl group bonded to the s-triazine ring. These are, for example, Wakabayashi et al., Bu
ll. Chem. Soc. Japan, 42, 2924 (1969), U.S. Patent 3,987,0
No. 37, FCSchaefer et al, J. Org.Chem., 29, 15
27 (1964). Hereinafter, these compounds are specifically exemplified, but the characters in [] are abbreviations of the compounds used hereinafter. They are, for example, 2,4,6-
Tris (trichloromethyl) -s-triazine [b-
1], 2-methyl-4,6-bis (trichloromethyl) s
-Triazine [b-2], 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2- (p-chlorophenyl) -4,6-bis (trichloromethyl) -s
-Triazine, 2-phenylthio-4,6-bis (trichloromethyl) -s-triazine [b-3], 2-benzylthio-4,6-bis (trichloromethyl) -s-triazine, 2- (p-tolyl ) -4,6-Bis (trichloromethyl) -s-triazine, 2- (p-methoxyphenyl) -4,6-bis (trichloromethyl) -s-triazine, 2-n-propyl-4,6-bis (Trichloromethyl) -s-triazine, 2- (α, α, β-trichloroethyl) -4,6-bis (trichloromethyl) -s-triazine, 2-styryl-4,6-bis (trichloromethyl)- s-triazine, 2,4,6-tris (dichloromethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s-triazine [b-4], 2-methyl-4,6
-Bis (tribromomethyl) -s-triazine, 2,4,6
-Tris (dibromethyl) -s-triazine and the like.
Of these, particularly preferred are, for example, 2,4,6-tris (trichloromethyl) -s-triazine, 2-phenyl-4,6-bis (trichloromethyl) -s-triazine, 2-methyl- 4,6-bis (trichloromethyl) -s
-Triazine, 2-phenylthio-4,6-bis (trichloromethyl) -s-triazine, 2,4,6-tris (tribromomethyl) -s-triazine or the like containing two or more trichloro or tribromomethyl groups. s-triazines. These s-triazines can be synthesized by reacting the corresponding nitrile compound with aluminum bromide in the presence of hydrogen chloride or via the corresponding imidate according to the above-mentioned literature.

The photopolymerization initiation system of the present invention can exhibit a remarkable effect only by a combination of the above-mentioned two components (a) and (b), but its use ratio is (a) :( b) weight ratio, preferably ,
In the range from 1:30 to 10: 1, particularly preferably from 1:15 to 4:
Range up to 1. The total amount of the photopolymerization initiation system, ie, the component (a) and the component (b), contained in the photopolymerizable composition of the present invention is preferably 0.1% to 30% by weight based on the ethylenic compound. And particularly preferably in the range of 0.5% to 20%.

The photopolymerizable composition of the present invention, in addition to the above components,
Other substances can be further added and mixed depending on the purpose of use.

For example, when a film-forming ability or a viscosity adjusting ability is required, an organic polymer substance may be added as a binder. Specific examples thereof include, for example, homo- or copolymers of (meth) acrylic acid, their esterified products, maleic acid, acrylonitrile, styrene, vinyl acetate, vinylidene chloride, etc., polyethylene oxide, polyvinylpyrrolidone, polyamide, polyurethane , Polyethylene terephthalate isophthalate, acetyl cellulose or polyvinyl butyral. These binders are preferably in a weight ratio to the ethylenic compound.
It can be added and mixed in a range of 500% or less, particularly preferably 200% or less.

In addition, hydroquinone, p-methoxyphenol,
Thermal polymerization inhibitors such as 2,6-di-t-butyl-p-cresol; coloring agents composed of organic or inorganic dyes and pigments; dioctyl phthalate, didodecyl phthalate, tricresyl phosphate, dioctyl adipate, triethylene glycol di Additives such as plasticizers such as caprylate, and other sensitivity improving agents such as tertiary amines and thiols can also be added.

When applying this composition to a color image reproduction technique,
Dye precursors, for example, dye leuco well-known in the technical field of color-forming materials and pressure-sensitive dyes such as those used in conventional color photographic films as described in JP-B-46-41346. Body can be added. Examples of the dye leuco include triarylmethane, bisarylmethane, xanthene compounds, fluorans, thiazine compounds, and compounds having a lactone, lactam, sultone, or spiropyran structure as a partial skeleton thereof.

Preferred amounts of the various additives described above are 2% or less of a thermal polymerization inhibitor, 20% or less of a colorant, 40% or less of a plasticizer, and 40% of a dye precursor in a weight ratio to the solid content of the photopolymerizable composition.
The range is as follows.

The form of the photosensitive material produced by using the present composition can be appropriately selected according to the purpose of use.

For example, sheets without solvent or diluted with a suitable solvent,
For example, coated and dried on polymer sheet, paper, metal sheet, and if necessary, further provided with an overcoat layer for blocking oxygen, and multiple types of photosensitive materials dispersed in small droplets in different phase media Various selections are possible, such as a form in which the composition is applied and a form in which the composition is encapsulated in microcapsules and applied on a sheet.

The exposure light source applicable to the composition of the present invention is not particularly limited, for example, a carbon arc, a high-pressure mercury lamp,
Xenon lamps, metal halide lamps, fluorescent lamps,
Light sources containing visible light of 600 nm or more, such as a tungsten lamp, a halogen lamp, a helium neon laser, and a semiconductor laser, can be particularly preferably used.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is not exceeded.

The abbreviations of the squarylium dye and s-triazine used in Examples and Comparative Examples correspond to those exemplified in the specification and the following compounds.

Examples 1 to 8 and Comparative Examples 1 to 4 The dissolution stability and the spectral sensitivity value of the evaluation items respectively represent the evaluation results obtained according to the following methods.

Dissolution stability This item evaluates the degree of stable solubility. 1% by weight of a squarylium dye and 5% by weight of an s-triazine compound are added to pentaerythritol triacrylate, and the mixture is heated and dissolved, and left at room temperature. After standing for one month, the case where no precipitation of the additive was observed was regarded as “good”, the case where the additive was slightly precipitated was “good”, and the case where crystal precipitation was remarkable was “poor”.

Spectral sensitivity value This item was obtained by evaluating and measuring the red light spectral sensitivity characteristics. 2 g of a methyl methacrylate / methacrylic acid copolymer (weight average molecular weight: 45,000, copolymerization ratio: 85/12) and 8 g of pentaerythritol triacrylate were dissolved in 120 g of methyl ethyl ketone to prepare a stock solution of a photosensitive solution. This stock solution was separated, and 1% by weight (based on solids) and 5% by weight of s-triazine (based on solids) described in Table 1 were added to prepare a sample photosensitive solution. Each of the obtained photosensitive liquids was applied to a grained and anodized aluminum sheet using a wheeler to a dry film thickness of 1.6 μm, and then dried at 70 ° C. for 3 minutes.

A polyvinyl alcohol aqueous solution was further applied to the surface, and an overcoat layer having a dry film thickness of 3 μm was provided to prepare a photosensitive material sample. Next, these samples were exposed for a certain period of time using a spectral irradiator ("RM-23-I", manufactured by Narumi), and then a developing solution (an aqueous solution containing 9% by weight of butyl cellosolve and 1% by weight of sodium silicate) was used. The photocuring speed for each wavelength was determined by developing according to (1). The spectral sensitivity value here indicates that corresponding to red light, that is, a value obtained as a ratio of the photocuring speed corresponding to 650 nm light to that corresponding to 550 nm. This value indicates the magnitude when the sensitivity for red light is compared to the sensitivity when the wavelength is shifted to a shorter wavelength side, and the larger the value, the better the spectral sensitivity. Is shown. As is apparent from Table 1, it is found that the photoinitiating system of the present invention has both good solubility and spectral sensitivity characteristics.

[Effects of the Invention] According to the present invention, a photopolymerizable composition exhibiting particularly excellent sensitivity to light having a wavelength of 600 to 700 nm and having excellent storage stability can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03F 7/027 G03F 7/028 G03F 7/004 C08F 2/50

Claims (1)

(57) [Claims] 1. A photopolymerizable composition comprising an addition-polymerizable ethylenically unsaturated compound and a photopolymerization initiation system, wherein the photopolymerization initiation system comprises: (a) a squarylium dye represented by the following general formula [I]: , [In the formula, R ₁ and R ₂ each represent an alkyl group or an aryl group which may have a substituent, and Ring A and Ring B each represent a benzene ring or a naphthalene ring which may each have a substituent. And (b) an s-triazine compound having at least one methyl halide group.