JPH01201652A - Photocurable composition - Google Patents

Abstract

PURPOSE:To obtain the title composition having remarkably high photosensitivity in an UV wavelength - a visible wavelength regions by incorporating a compd. having at least two ethylenically unsatd. bonds and specified polythiol compd. and iron complex salt in the composition as an essential component. CONSTITUTION:The compd. having at least two ethylenically unsatd. bonds, the polythiol compd. shown by formula I and the iron complex salt shown by formula II are incorporated in the composition as the essential component. In the formula, R is (n) valent org. residual group, (n) is an integer of 2-6, Cp is cyclopentadienyl group which may be substd. Ar is an aromatic hydrocarbon group which may be substd. X is an acid residual group. Thus, the composition having the remarkably high photosensitivity at an UV ray - a visible ray is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a photocurable composition, which has extremely high photosensitivity particularly in the ultraviolet to visible range and is less likely to be inhibited by oxygen. This invention relates to a photocurable composition.

[Prior Art] Photosensitive resins whose solubility changes upon irradiation with light are widely used in the fields of printing and electronic materials, particularly as photosensitive printing plates and photoresists. In these fields, exposure technology using laser beam scanning has recently made remarkable progress, and along with this, there is a need for photosensitive materials that have photosensitive characteristics suitable for the above exposure methods, that is, high sensitivity to visible light. . Conventionally known photosensitive resins are sensitive to wavelengths mainly in the ultraviolet region, have insufficient sensitivity, and are not suitable for laser exposure.

Various studies have been conducted on photosensitive resins that are highly sensitive to visible light. There are various types of photosensitive resins, such as photodimerization types, photopolymerization types, and photodegradation types, but photopolymerization types based on a chain reaction mechanism are advantageous in achieving high sensitivity. Much of the research on photosensitive resins concerns photopolymerization types, especially photoradical polymerization types. Regarding the photopolymerization type, various highly efficient photopolymerization initiator systems have been discovered.
Under ideal exposure conditions, fairly satisfactory photosensitivity characteristics can be obtained. However, photo-radical polymerization compositions generally have a serious weakness in that the presence of oxygen (air) significantly inhibits curing and makes it impossible to obtain sufficient sensitivity. It makes it difficult to use. In order to avoid this problem, measures have been taken such as performing exposure in a vacuum or inert gas, or providing an oxygen-blocking and transparent coating on the surface of the photosensitive resin. There are various problems, such as complicated operations and deterioration of resolution if a coating is provided on the surface.

Various additives have been proposed to reduce the effects of oxygen, but all of them are insufficient, even if they have some effect, and no one has yet been found that has a satisfactory effect.

As a photocurable composition that is less affected by oxygen, so-called ene-curing compositions based on the addition reaction of unsaturated groups and thiol groups are used.
The thiol composition is known. This composition is also based on a chain reaction similar to the photopolymerization type, and has the potential to increase sensitivity, but there is less research on it compared to the photopolymerization type. In this composition, aromatic ketones such as benzophenone are known as photoinitiators, but in this case, even if the influence of oxygen is small, the original sensitivity is insufficient, and most of the photosensitivity is in the visible range. It is unsuitable for use as a laser-sensitive material.

[Problems to be Solved by the Invention] As described above, a photosensitive resin composition that has high photosensitivity to visible light even in the presence of oxygen has not yet been found, and its development is eagerly awaited.

The present inventor focused on the ene-thiol composition, which has an advantage in curability in the presence of oxygen but has little research, and as a result of repeated studies on increasing sensitivity and expanding the photosensitive range,
The present invention was achieved by discovering that extremely good results can be obtained when a certain specific compound is used as a photoinitiator.

[Means for Solving the Problems] The present invention is a photocurable composition characterized by containing the following components as essential components.

(a) A compound having at least two ethylenically unsaturated bonds, (b) A polythiol compound represented by the following general formula (I), R(SH)□ (I) (wherein, R is an n-valent organic n is an integer from 2 to 6); Ar represents an unsubstituted or substituted aromatic hydrocarbon; and X represents an acid residue. ) The present invention will be explained in detail below.

In the photocurable composition of the present invention, the first essential component (a), a compound having at least two ethylenically unsaturated bonds, is one that is compatible with other components in the composition. There is no particular restriction on the structure, but those containing a vinyl group or allyl group in the form of an ether, ester, or urethane bond, and those in the form of (meth)acrylic acid derivatives are common. Although (meth)acrylic acid derivatives have rarely been used as components of ene-thiol photosensitive compositions, they can be suitably used in the composition of the present invention. There is no particular restriction on the molecular weight, and in addition to the seven-piece shape, oligomer and prepolymer shapes can also be used. When the present composition is used in the form of a film, it is particularly preferable to contain a polymer having an unsaturated group in its side chain or main chain, which also serves as a binder.

Specific examples of such unsaturated compounds include (meth)acrylic esters of polyhydric alcohols, such as pentaerythritol tri(meth)acrylate, pentaenethritol tetra(meth)acrylate, trimethylolpropane tri(meth)acrylate, and ethylene. glycoldi (
Addition products of compounds having multiple epoxy groups and (meth)acrylic acid such as meth)acrylate, hexanedityl di(meth)acrylate, allyl esters of polybasic acids such as diallyl phthalate, triallyl isocyanurate, etc. ) Allyl acrylate (co)polymer, (co)polymer of (meth)acrylic acid, maleic acid, etc. added to glycidyl (meth)acrylate or allyl glycidyl ether, unsaturated compound having a hydroxyl group Examples include unsaturated (poly)urethane obtained by polyaddition of allyl alcohol, (meth)acrylic 12-hydroxyethyl, etc. and diisocyanate, and unsaturated polyester obtained by polycondensation reaction of maleic acid and diols. These substances may be used alone or in combination of two or more.

Next, component (b), which is the second essential component, has the general formula (I
) is a polythiol compound represented by

R(SH)n (I) where n is an integer of 2 to 6, and R represents an n-valent organic residue. There is no particular restriction on the structure of R, which may include an ester bond, an ether bond, etc. in addition to a carbon-carbon bond, and may have a substituent such as a hydroxyl group or a halogen. There are no particular restrictions on the molecular weight, etc., but those having a carbon atom number in the range of 2 to 30 are generally used, and the photocurable composition of the present invention is substantially When used as a non-flowing composition, one having a boiling point of about 150° C. or higher at atmospheric pressure is preferred.

Examples of such compounds include di(2-mercaptoethyl) ether, 1,6-hexanedithiol, ethylene glycoldithioglycolate, ethyleneglycoldithiopropionate, 1,4-butanedioldithiopropionate, trimethylolpropane. Tris (thioglycolate), trimethylolpropane tris (β-thiopropionate), pentaerythritol tetrakis (
thioglycolate), pentaerythritol tetrakis (β-thiopropionate), etc.

Among these, those having a thiopropionate structure are particularly preferred.

Component (C), which is the third essential component, is a component that acts as a photoinitiator, and is a component that is a significant feature of the present invention. Component (C) is 2 represented by general formula (n)
A complex salt containing valent iron, in which C0 represents a cyclopentadienyl group, and may have an alkyl group having 1 to 8 carbon atoms or an alkenyl group having 2 to B carbon atoms as a substituent. good. Ar represents an aromatic hydrocarbon coordinating to an iron atom, which may be a fused ring type, or an alkyl group having 1 to 12 carbon atoms, or an alkyl group having 2 to 12 carbon atoms.
alkenyl group, alkoxy group having 1 to 8 carbon atoms, cyano group, halogen, phenoxy group, phenyl group, monocarboxylic acid ester group having 2 to 6 carbon atoms, 2 carbon atoms
It may have ~5 alkanoyl groups or benzoyl groups. Examples of Ar include benzene, toluene, xylene, cumene, chlorobenzene, anisole, biphenyl, naphthalene, methylnaphthalene, pyrene, and the like. X represents an acid residue, and preferable examples include halogen, CD, On, BF4, PFe, ASFe, 5
bFs is mentioned.

Such complex salts are substances originally proposed as photocationic polymerization initiators for epoxy resins, etc. (J. Rad, Cur.
i ng, Oct., 1986. The structure of p, 2X=PFe is available from Ciba Geigy as “IRQACtJR”.
E" 261. This material is preferably used for the purposes of the present invention.

The above compound was developed as a cationic photopolymerization initiator as mentioned above, but the present inventor believes that this substance is also effective as a photoradical initiator, and that it is effective for ene-thiol-based curing reactions based on a radical chain mechanism. We have found that this method can be started extremely efficiently. This compound has wavelengths from the ultraviolet region to 5
It has a wide photosensitive wavelength range that extends to the visible range of 0.00 nm, and exhibits good photosensitivity to various light sources. A remarkable feature of this initiator is that it can be highly efficiently sensitized with other photosensitizers. Therefore, the combination of appropriate photosensitizers is extremely effective. Although it is possible to obtain good photosensitivity characteristics even when compound (C) is used alone, sensitivity can be further greatly improved by using a sensitizer in combination, and the sensitivity can be further improved by selecting a sensitizer. Wavelength range from ultraviolet to 700n
It can be set arbitrarily over the entire visible range up to m.

Preferred as the sensitizer are aromatic hydroxides.

compound, or xanthine-based, thioxanthin-based,
Dyes such as thiazine, acridine, oxazine, cyanine, and merocyanine, such as Michler's ketone, 4,4-bis(diethylamino)benzophenone, benzanthrone, thioxanthone, and eosin Y.
1 erythrosine, Rhodamine B10-Damine 6G, methylene blue, Nile blue, acridine yellow, acridine orange, and the like. When red dyes such as rhodamine and eosin are used, good photosensitivity is imparted to blue to green light with a wavelength of around 500 nm.
If a blue dye such as Nile Blue is used, it is possible to form an image at a wavelength of 600 to 700 nm.
Good photosensitivity is imparted to the red light of, for example, image formation using a helium-neon laser (oscillation wavelength: 633 nm) is possible.

In the photocurable composition of the present invention, component (a>) and component (
The ratio b) is generally around a ratio where the unsaturated group and the thiol group are equivalent, but this is not strict, and if the molar ratio of the two is in the range of 4:1 to 1:4. There is no particular problem.

When using a component (a) that has an unsaturated group that is easily radically polymerized alone, such as a (meth)acryloyl group, a polymerization curing reaction using only the unsaturated group may be carried out in parallel with the addition reaction with the thiol. occurs, so in this case (
a): (b) = up to about 100:1 (a>component can also be used in excess.

The amount of the photoinitiator component (C) is not particularly limited, but in order to particularly exhibit the effects of the present invention, it is preferably 0.05% to 20% by weight, more preferably 0.05% to 20% by weight based on the entire composition. It is preferable to mix it in a range of .1 to 10% by weight. (
If the amount of component C) is less than the above range, the amount of radicals that initiate the curing reaction when irradiated with actinic light will be small, so the photocurability of the composition will be significantly reduced, and the above-mentioned If an excessive amount exceeding the range is used, the photosensitivity will also be lowered due to the effects of shielding of effective light.

When a photosensitizer is used in addition to the above ingredients, the preferred amount of the photosensitizer added varies depending on the type of photosensitizer, but is generally 0.05 to 5% by weight based on the entire composition. It is preferable that the photocurable composition of the present invention, which is within the above range, contains a storage stabilizer in addition to the above-mentioned components. The composition of the present invention generally has insufficient storage stability, and if no stabilizer is added, it tends to become insolubilized or change in sensitivity even in the dark.

Acids and radical inhibitors are effective as stabilizers, but acids are particularly preferred, such as phosphoric acid, acetic acid, formic acid, propionic acid, glycolic acid, lactic acid, benzoic acid, oxalic acid, and malonic acid. acid, succinic acid, glutaric acid, malic acid, tartaric acid, citric acid, etc. Preferred among these are carboxylic acids, particularly polybasic carboxylic acids, and malonic acid is particularly preferred. The preferred amount of the acid added as a stabilizer varies depending on the type of acid and the type of components (a>, (b)), but is generally 0.1 to 50% by weight, more preferably 0.1 to 50% by weight based on the entire composition.
It ranges from 5 to 20% by weight. If the amount added is less than the above range, the stabilizing effect will be insufficient, and if an excessive amount exceeding the above range is used, the curing reaction will be accelerated,
This may actually worsen stability.

In addition to the above-mentioned components, the photocurable composition of the present invention uses, as a binder, an organic polymer substance that is compatible with each of the above-mentioned components and has film-forming ability in order to impart film-forming ability. It can be included. For many uses such as PS plates and photoresists, it is preferable to use such a binder substance in combination to impart film-forming ability to the photocurable composition.

Any polymeric substance may be used as long as it is soluble in the solvent and compatible with each component of the composition, but particularly preferred are water, alkali, acid, etc. It is a polymeric substance that is soluble in aqueous solutions and therefore can be developed with an aqueous developer. Examples of such polymers include copolymers containing unsaturated carboxylic acids such as (meth)acrylic acid and maleic acid as one component, polyvinyl alcohol, polyvinylpyrrolidone, copolymerized nylon,
Examples include alkali-soluble novolac resins. In order to obtain particularly high photosensitivity, it is preferable to use a polymer having an unsaturated group in the side chain or main chain.

In that case, this polymer can be considered as component (a). Examples of such polymers have already been mentioned in the explanation of component (a), but in particular, copolymers of (meth)acrylic acid, maleic acid, etc. have an equivalent amount or less with respect to the carboxyl group. Those to which a certain amount of glycidyl (meth)acrylate is added are preferable because they have excellent photosensitivity and water developability.

In addition, various additives such as a thermal polymerization inhibitor, an adhesion improver, a plasticizer, and a filler can be added to the photocurable composition of the present invention, if necessary.

The photocurable composition of the present invention has an extremely wide range of uses such as printing plates, photoresists, paints, printing inks, and adhesives, but particularly useful uses include printing plate materials for lithographic printing, photoresists, etc. It is a photosensitive image forming material. In these uses, the photocurable composition of the present invention is dissolved in a solvent to form a solution, and the solution is coated on a support by a known method.
It is generally dried and used as a film.

The support used here is generally a planar material that does not undergo significant dimensional changes, examples of which include aluminum, copper, and zinc. Examples include metals such as iron, polymeric substances such as polyester, polystyrene, polymethyl methacrylate, and nylon, glass, silicon, silicon oxide, and ceramics. It is also possible to use a material in which two or more thin films of these materials are laminated, or a thin film of another material is formed on the surface of one material by means such as vapor deposition. Furthermore, the surface of the above-mentioned support can be subjected to treatments such as graining, N@ etching, chemical etching, electrolytic oxidation, corona discharge, etc., or can be coated with an adhesive layer, an antihalation layer, etc. It is also possible to provide one.

In addition, using a support coated with an ink-repellent silicone rubber layer (or by coating a silicone rubber layer on a coating film of the photosensitive composition of the present invention), negative-type (or positive-type) water It is also possible to produce a blank lithographic printing plate.

A major feature of the photocurable composition of the present invention is that it exhibits good curability even in the presence of oxygen, and although it exhibits a sufficiently high sensitivity for practical use as it is, it can achieve even higher sensitivity if oxygen is blocked. It will be done. Methods for blocking oxygen include exposing the photosensitive composition in a vacuum or in an inert gas atmosphere such as nitrogen or carbon dioxide, or applying a solution of an oxygen-blocking and soluble polymer such as polyvinyl alcohol on the photosensitive composition film. There are methods of coating and drying the photosensitive film, and methods of adhering a transparent and oxygen-blocking plastic film such as polyester, polyvinyl alcohol, polyvinylidene chloride, etc. to the surface of the photosensitive film. When used as a dry film resist, the support film acts as an oxygen-blocking layer, so extremely high sensitivity can be obtained even though a relatively thick photosensitive resin film is used.

The image-forming material prepared from the photocurable composition of the present invention is imagewise exposed by a conventional photographic method, that is, by exposing a negative film in close contact with light, or by a method such as projection exposure, or by a method such as scanning exposure with a laser beam. An image can be formed by dissolving and removing the unexposed areas with a solvent that dissolves the photosensitive layer. The resulting image has good ink receptivity and acid resistance, so it can be suitably used as a printing plate or resist.

The present invention will be described below based on Examples and Comparative Examples.

Note that all "parts" herein are parts by weight.

Further, all operations in Examples and Comparative Examples were performed under red light at dark solstice.

(Synthesis of polymer for binder) (A) 30 parts of styrene, 30 parts of ethyl acrylate, 140 parts of methacrylic, 50 parts of ethyl alcohol, and 50 parts of methyl ethyl ketone were mixed, 1 part of azobisisobutyronitrile was added, and the mixture was stirred. The mixture was reacted at 80°C for 8 hours. The obtained polymer solution was used as it was (without separating the polymer) for composition preparation.

(B) After carrying out the polymerization reaction in exactly the same manner as in (A),
The obtained polymer solution was diluted with 8100 parts of ethyl alcohol and methyl ethyl ketone, 40 parts of glycidyl methacrylate and 1 part of pyridine were added thereto, and the mixture was reacted at 75° C. for 8 hours with strong stirring. The resulting solution was used as it was (without separating the polymer) for composition preparation.

(C) 20 parts of allyl methacrylate, 20 parts of methyl methacrylate, 150 parts of methacrylate, 100 parts of ethyl alcohol
1 part of methyl ethyl ketone, 1 part of azobisisobutyronitrile was added, and the mixture was heated to 80°C with strong stirring.
The mixture was allowed to react for 4 hours.

The obtained polymer solution was used as it was for composition preparation.

Examples 1 to 8, Comparative Examples 1 to 2 100 parts of binder polymer (B) (as solid content) and each component of thiol, photoinitiator, photosensitizer, and stabilizer were added to an ethyl alcohol/methyl ethyl ketone mixture ( I/1
) to prepare a solution with a solid content of 15%, which was coated on an aluminum plate whose surface had been treated with a sodium metasilicate aqueous solution using a wire bar coater to obtain a dry coating thickness of 15%. It was coated to a thickness of about 5 μm and dried at 80° C. for 2 minutes during electric heating and ventilation drying to produce a PS plate.

A 21-step step tablet (S
(manufactured by Touffer) and Test Chart negative film were placed on the film and exposed to light under the following conditions to examine the photosensitive characteristics. Some samples were also tested for photosensitive properties after two weeks of storage in an electrically heated oven at 50°C.

<1> Using a 3KW ultra-high pressure mercury lamp ("Jet Light" 3300 manufactured by Oak Seisakusho Co., Ltd.), from a distance of 1 m for 1 second,
Or expose for 5 seconds.

(2) Expose for 5 seconds from a distance of 25 cm using a 60W tungsten lamp.

(3) Scanning exposure using an argon laser beam (spot diameter 50 μm) that mainly emits visible light with a wavelength of 488 nm and 514.5 mm under conditions of a light intensity of 10 mW on the printing plate, a scanning speed of 150 m/sec, and a scanning line density of 90 lines/mm. do.

After exposure as described above, development was performed using a 1% aqueous sodium carbonate solution. The sensitivity is as shown in Table 1.

All of the compositions based on the composition of the present invention exhibited good sensitivity and good image reproducibility. In particular, when a photosensitizer is used in combination, the sensitivity is even more remarkable. Furthermore, when dyes were used as sensitizers (Examples 4 to 8), excellent photosensitivity to visible light was obtained. The storage stability is insufficient when no stabilizer is added, but is extremely good when an acid is added as a stabilizer.

Note that when only a conventionally known aromatic carbonyl compound is used as a photoinitiator (Comparative Example 1.2), the photosensitivity is significantly inferior to that of the composition of the present invention.

Example 9 Binder polymer (A>50 parts (as solid content), 25 parts of pentaerythritol triacrylate (“A-TMM-3°” manufactured by Shin Nakamura Chemical Co., Ltd.), 25 parts of TMTP,
A solution having a solid content concentration of approximately 15% was prepared by dissolving 2612 parts of "Irgacure", 1 part of Rhodamine 6G, and 2 parts of malonic acid in ethyl alcohol, and a PS plate was prepared in the same manner as in Examples 1 to 8. .

The obtained PS plates were exposed under the exposure conditions (2) in Examples 1 to 8, and developed with a 1% aqueous sodium carbonate solution.

The number of step tablet curing stages was 6.

Example 10 100 parts of polymer (C) for binder (as solid content)
, 20 parts of BDTP, 2 parts of "Irgacure" 261), and 1 part of Rhodamine 6G were dissolved in ethyl alcohol to prepare a solution with a solid content concentration of about 15%. A PS plate was prepared in the same manner as in Examples 1 to B. Expose under exposure condition (2),
It was developed with a 1% aqueous sodium carbonate solution. The number of step tablet curing stages was 5.

Example 11 100 parts of binder polymer (B) (as solid content),
20 parts of TMTP, 2612 parts of "Irgacure", 0.5 parts of Rhodamine 6G, 2 parts of malonic acid in ethyl alcohol/
A solution with a solid content concentration of approximately 30% is prepared by dissolving it in a methyl ethyl ketone mixture (I/1), and this is coated on a 25 μm thick polyethylene terephthalate film (“Lumirror” manufactured by Toshishiku Co., Ltd.) after drying. A dry film resist was prepared by casting to a thickness of approximately 50 μm and drying at 70° C. for 5 minutes.

The coated surface of the obtained dry film was pressed and adhered to the copper surface of a well-polished copper clad laminate at 60°C, and a negative film having a step tablet and a circuit pattern was adhered thereon. Exposure was performed for 1 second from a distance of 25 cm using a 60W tungsten lamp. "Lumirror" was peeled off and developed with a 1% aqueous sodium carbonate solution. The resulting resist pattern faithfully reproduced the negative film and was firmly adhered to the copper surface. The number of step tablet curing steps was 5.

Further, when this was etched with an etching solution containing ferric chloride and hydrochloric acid, the resist image was not affected by the etching solution at all, and the etching could be performed satisfactorily.

Note that even when the dry film was left for one week after being pressure-bonded to a copper surface, there was no change in sensitivity or developability, and the stability was good.

[Effects of the Invention] As explained above, the photocurable composition of the present invention exhibits high photosensitivity to ultraviolet to visible light even in the presence of oxygen, and is particularly sensitive to long wavelength light such as laser scanning exposure. It is extremely useful for applications such as printing plates and photoresists that require high sensitivity.

Patent applicant: Toshi Co., Ltd.

Claims (1)

[Scope of Claims] 1. A photocurable composition containing the following components as essential components. (a) A compound having at least two ethylenically unsaturated bonds, (b) A polythiol compound represented by the following general formula (I), R(SH)_n(I) (wherein R is an n-valent organic residue and n is an integer of 2 to 6.) (c) Iron complex salt represented by the following general formula (II), [Cp-Fe^■-Ar]X^■(II) (wherein, C_p is 2. The composition according to claim 1, further comprising an unsubstituted or substituted cyclopentanenyl group, Ar represents an unsubstituted or substituted aromatic hydrocarbon, and X represents an acid residue. . 3. The composition according to claim 1 or 2, further comprising a stabilizer. 4. The composition according to claim 2, wherein the sensitizer is an aromatic carbonyl compound or one or more dyes selected from xanthene, thioxanthene, acridine, oxazine, thiazine, cyanine, and merocyanine. thing. 5. The composition according to claim 3, characterized in that the stabilizer is an acid.