JPS5941444B2 - Photopolymerizable composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION By adding a specific photopolymerization initiator and a monothiol derivative, the present invention provides improved photosensitivity, moldability into a stable shoulder shape of relief, and storage stability related to these properties. The present invention relates to a photopolymerizable composition.

Generally, a resin composition consisting of a resin such as an unsaturated polyester and an addition polymerizable compound having an ethylenic double bond is photopolymerized by irradiating the composition with actinic light in the presence of a photopolymerization initiator. It is known that a cured product can be formed by polymerization and crosslinking, and such a cured product is applied in the printing field as a photosensitive resin plate.

The photopolymerizable composition is required to have high photosensitivity and a very stable shoulder of the relief of the molded resin plate, and also that such properties do not deteriorate during storage, i.e., sensitivity and stability over time. A stable shoulder shape without deterioration in formability is desired.

Although various studies have been conducted and proposals have been made to satisfy these requirements, no practical means for simultaneously satisfying these three requirements has yet been proposed.

For example, even if a stable shoulder shape is provided by increasing the sensitivity, the sensitivity deteriorates markedly over time, and the storage stability of the composition is poor and it tends to gel. In addition, it is extremely difficult to suppress the decrease in sensitivity over time, and for this purpose, it is necessary to always store it in an inert gas or seal it in a gas-barrier plastic, glass, or metal container. It's not practical. JP-A-50-117502 is an attempt to improve such drawbacks of photopolymerizable compositions, and the present inventors have arrived at the present invention as a result of intensive research to further improve the problem.

That is, the present invention provides a) the following general formula (I) as a photopolymerization initiator:
8 [However, in the formula, H, Cl, Cl to C5 alkyl group, C
1 to C5 alkoxy group, A is a 6-membered aromatic group, R is
represents a C1 to C, O alkyl group, a C7 to C, aralkyl group, or a -(-CnH2nO+RIlRl group).

Here, n is an integer of 2 to 5, m is an integer of 1 to 5, and R1 is C
Indicates a 1-C5 alkyl group. ] and b) an addition polymerizable compound and a soluble polymer having an ethylenic double bond, characterized by containing a heterocyclic monothiol derivative and/or an aromatic monothiol derivative. It is a polymerizable composition.

Examples of the compound represented by the general formula (1) in the present invention include benzyl (Benzyl) represented by the following formula.
Compounds corresponding to il) in which one carbonyl group is converted to a ketal (not necessarily produced by this method).

), for example, in addition to benzyl dimethyl ketal represented by the following formula, benzyl di(β-phenyrule ethinole) ketal, benzyl diethyl ketal, benzyl dipropyl ketal, benzyl di(2-methoxyethyl) ketal, benzyl di( 2-ethoxymethyl)ketal, benzyludi(2-methoxyethoxyethyl)ketal, benzyludi(2-ethoxyethoxyethino(ha)ketal, 4,4'-dimethylbenzyl-dimethylketal, 2,21-dimethoxybenzyl-diethyl ketal, Examples include 4,4'-dichlorobenzyl dimethyl ketal.

Among these, preferable ones are those in which R in general formula (1) is +C
nH2. O-)-. It is a compound represented by, especially benzyludi(2-methoxyethyl)ketal. These photopolymerization initiators may be used alone or in combination of two or more. Further, a conventionally known photopolymerization initiator may be used together with a). Such photopolymerization initiators include benzoin derivatives such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether, anthraquinones such as anthraquinone and ethyl anthraquinone, benzophenones, eosin,
Examples include pigments such as fluorescein. These photopolymerization initiators are usually used at 0% per 100 parts by weight of the photopolymerizable composition.
．． It is used in a proportion of 0.01 to 10.0 parts by weight.

Next, as an example of b) as the second component, first, as a heterocyclic monothiol derivative, 2-mercaptobenzothiazole itself or an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a nitro group, a halogen Derivatives of 2-mercaptobenzothiazole whose nucleus is substituted with an atom, etc.; 2-mercaptobenzoxazole itself or whose nucleus is substituted with an alkyl group such as a methyl group, ethyl group, isopropyl group, a nitro group, a halogen 7 atom, etc. , derivatives of mercaptobenzoxazole: 2-mercaptobenzimidazole, and N-methyl-2-mercaptobenzimidazole, N-ethyl-2-mercaptobenzimidazole, N-isopropyl-2-mercaptobenzimidazole, N-phenyl-2- N-substituted derivatives of 2-mercaptobenzimidazole such as mercaptobenzimidazole; Derivatives of 2-mercaptobenzimidazole further substituted with a nucleus such as an alkyl group such as a methyl group, ethyl group, or isopropyl group, a nitro group, or a halogen atom; 2-
Examples include mercaptothiazole, 2-mercaptoimidazole, and N-alkyl and allyl substituted derivatives; and metal salt derivatives of the above-mentioned heterocyclic monothiol derivatives, such as sodium, potassium, calcium, and zinc.

Particularly preferred compounds include 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, and 2-mercaptobenzothiazole.
Examples include mercaptobenzimidazole, metal salts thereof, and nuclear substituted products. Examples of aromatic monothiol derivatives include thiophenol, 2-nitrothiophenol, thionaphthol, thiosalicylic acid, aliphatic and aromatic esters of thiosalicylic acid, mercaptobenzoic acid, aliphatic and aromatic esters of mercaptobenzoic acid, and metal salts. Derivatives etc. can be listed. These may be used alone or in combination of two or more.

The present invention is characterized by the use of monothiol derivatives as described above, and when polyvalent thiols such as tolylene-24-dithiol and lauryl mercaptan are used, the storage stability of the photopolymerizable composition is improved. becomes worse,
It becomes easier to gel.

The amount of the above monothiol derivative used is 0.001 to 5 parts by weight per 100 parts by weight of the photopolymerizable composition.

Of course, the amount to be used can be determined as appropriate depending on the intended use of the composition, but if the amount used is less than 0.001 parts by weight, the effect on improving sensitivity and stabilizing the shape of the relief shoulder will be small. If the amount is more than 5 parts by weight, it is not preferable because the compatibility with the composition becomes insufficient. Next, the addition polymerizable compound having an ethylenic double bond used in the present invention exhibits a liquid or solid state at room temperature and normal pressure, and can undergo a polymerization reaction by irradiation with actinic light in the presence of a photopolymerization initiator. It is a compound.

Such addition-polymerizable compounds are rarely used alone, but are used in the coexistence of various soluble polymers.

The soluble polymer is a polymeric binder that is compatible with the addition polymerizable compound, and may be liquid or solid at room temperature. Therefore, depending on the properties of the soluble polymer and the amount used, the composition as a whole may exhibit a liquid state or a solid state at room temperature, but the present invention is not limited to this, and the effects of the present invention can be expected in any case. I can do it. Furthermore, it is preferable that the soluble polymer used also has a functional group that reacts with the functional group (ethylenic double bond) of the addition polymerizable compound by irradiation with actinic rays in the presence of a photopolymerization initiator. Examples of addition polymerizable compounds having an ethylenic double bond include acrylic acid, methyl acrylate, ethyl acrylate,
Acrylic acid monoesters such as lauryl acrylate and phenyl acrylate, glycol diacrylate esters such as ethylene glycol diarylate, polyethylene glycol diacrylate, propylene glycol diacrylate, and polypropylene glycol diacrylate, glycerin triacrylate, and trimethylol propane. Triacrylates, particularly triacrylic esters of triols, polyacrylic esters of polyols, and meta-acrylates corresponding to these, as well as acrylamide, methacrylamide, N-methylolacrylamide, diacetone acrylamide,
Examples include acrylamide derivatives such as N,N marylene bisacrylamide and N-butoxymethylacrylamide, vinyl acetate, styrene, vinyl toluene, diallyl phthalate, diallyl isophthalate, and triallyl cyanurate.

These addition polymerizable compounds having an ethylenic double bond can be used alone or in combination of two or more. As the soluble polymer, it is necessary to select one that has good compatibility with the addition polymerizable compound as described above, but depending on the type of addition polymerizable compound, polyamide resin, polyester resin, epoxy resin, polymethyl methacrylate resin, Cellulose acetate, polyvinyl alcohol and derivatives or copolymers thereof can be used.

Furthermore, among the above-mentioned soluble polymers, polymer compounds having ethylenic double bonds, such as unsaturated polyester resins,
Preferred are unsaturated polyamide resins, unsaturated polyurethane resins, polybutadiene resins, and copolymers of these with styrene, acrylonitrile, and the like. Further, a filler may be added to the photopolymerizable composition of the present invention to improve the physical properties after curing, and a plasticizer or the like may be added to the photopolymerizable composition to impart flexibility.

In the present invention, known polymerization inhibitors can be used to further improve the storage stability of the composition.

For example, phenols, hydroquinones, quinones,
Mention may be made of amines and N-nitrosamines. Particularly preferred are nitrone amines. These storage stabilizers have little effect on the photocuring reaction rate, and are added in the amount necessary to simply suppress or prevent reactions caused by heat during storage, and the amount is 100 parts by weight of the photopolymerizable composition. It is in the range of 0.001 to 1.0 parts by weight. The photopolymerizable composition of the present invention can be obtained by thoroughly mixing the above-mentioned components.

When the composition is solid, the composition can be formed by dissolving it in a solvent and then forming it into a sheet, or by forming it into a sheet by hot rolls or rolling. They can be used as photosensitive materials by coating them on a support such as a metal plate such as aluminum or iron plate, or a plastic sheet made of polyethylene terephthalate or the like. Furthermore, even when the composition is a liquid, it can be used by coating it on a support in the same manner.

In order to use the photopolymerizable composition of the present invention for producing printing plates, iron, steel plates, metal plates such as aluminum, natural rubber,
It is convenient to use a rubber sheet such as synthetic rubber or a plastic sheet such as polyethylene terephthalate as a support and form the photopolymerizable composition thereon in a layer having a thickness of 0.2 to several millimeters.

The layer may be adhered to the support via an adhesive layer if necessary. Next, the photopolymerizable composition is cured by irradiating actinic rays through a negative film or a positive film having an image area. The time required for this photocuring, that is, the exposure time, is usually from several minutes to more than ten minutes, but when the photopolymerizable composition of the present invention is used, this time is significantly shortened due to its high sensitivity. The shape of the shoulder is a trapezoid with a wide base, that is, the shape of Mt. Fuji, and it is possible to form a relief that can withstand sufficient printing. Depending on the properties of the photopolymerizable composition, a tungsten bulb, xenon lamp, mercury lamp, chemical fluorescent lamp, etc. can be used as a light source for exposure;
Those that emit actinic rays rich in ultraviolet rays of 0 mμ are preferable.

The unexposed non-image area is removed by washing with a dilute alkaline aqueous solution (eg, soda carbonate, caustic soda aqueous solution), organic solvent, or the like.

Then, by drying, a printing original plate having a strong relief can be obtained. When producing a printing original plate using the photopolymerizable composition of the present invention, the sensitivity is higher than that of conventional photopolymerizable compositions, so the exposure time is significantly shortened. This reduces time and greatly improves productivity.

Moreover, the sensitivity of the photopolymerizable composition and the ability to form a stable shoulder shape with relief over time change less than those of conventional compositions, as shown in the Examples described later, and are extremely useful from a practical standpoint. Furthermore, the shape of the shoulder of the photocured relief obtained from the photopolymerized surrounding composition is extremely stable, that is, the area of the base of the relief adhering to the support is extremely large compared to the area of the top of the relief. It exhibits sufficient resistance to the external force exerted on the relief by the printing roller, and there is no possibility of relief falling off, folding, etc., that is, relief loss. When the photopolymerizable composition of the present invention is cured by irradiation with actinic rays, the cured relief has a tensile strength of 100 kg/~
As mentioned above, it has a Shore hardness (D scale) of 50 degrees or more, has excellent dimensional stability, and has good swelling resistance against organic solvents such as alcohol, acetone, benzene, etc., so it can print delicate lines. Precision printing allows for faithful reproduction,
It is useful as an original plate for color printing.

The photopolymerizable composition of the present invention can be used in a wide range of applications, such as paints, adhesives, displays, lenses, and photoresists, in addition to printing materials such as printing original plates and flexible graph plates.

The present invention will be explained in detail below with reference to Examples.

Note that "part" in the examples means [part by weight], and the acid value is the number of milligrams of potassium hydroxide required to neutralize 1 gram of the composition. Example 1 226 parts of fumaric acid, 58 parts of trimellitic anhydride, 110 parts of adipic acid and 286 parts of diethylene glycol were heated at 100 to 120° C. for 0.5 hours under a nitrogen atmosphere, and then heated to 200
The reaction was carried out at ℃ for 4 hours to synthesize an unsaturated polyester having an acid value of 120.

65 parts of this unsaturated polyester, 1 part of methacrylamide
0 parts, triethylene glycol dimethacrylate 25
1 part of benzyl methyl ketal, 0.045 part of 2-mercaptobenzimidazole, and 0.02 part of N-nitrosodiphenylamine were mixed to obtain a photopolymerizable composition.
The obtained photopolymerizable composition and the product that was placed in an open container in a constant temperature dryer at 30°C and left for the time shown in Table 1 below were exposed to light for photopolymerization and the unexposed areas were subjected to the following method. A letterpress printing original plate was obtained by washing and drying.

In other words, place the negative film on a glass plate set horizontally,
A polyethylene terephthalate film having a thickness of 12 microns was laminated thereon, and the composition was further coated thereon to a thickness of 0.7 mm.

Next, a 0.3 mm steel plate with an anti-halation layer and an adhesive layer was placed on top of this composition, and a light source of three 60W ultraviolet fluorescent lamps was used from the glass surface to expose the negative film to a light transmittance of 4%. It was exposed for only the time required for the halftone dots to adhere. Next, the unexposed areas were removed by washing with a dilute alkaline aqueous solution and then dried to obtain a resin plate with tough relief. The sensitivity of the photopolymerizable composition, the shoulder shape of the isolated point relief with a diameter of 180μ of the molded plate obtained by photocuring, and
Table 1 shows the above characteristics of the photopolymerizable composition that was changed over time.

Here, the reciprocal number (1/min) of the time required for the halftone dots of the negative film having a light transmittance of 4% to adhere is used as the sensitivity.

In addition, the shape of the shoulder is defined by the area of the top of the relief head (corresponding to the size of the independent point of the negative) St, and the adhesive area Sb of the base of the relief with the support body, V? Expressed in 100/St. ! hundred? A large value of /St indicates that the shoulder shape of the relief is stable. Comparative Example 1 was carried out in the same manner as in Example 1, using benzoin ethyl ether instead of benzyl dimethyl ketal. From Table 1, it can be seen that Example 1 has higher sensitivity than Comparative Example 1, the shape of the shoulder of the relief is larger, and the change in sensitivity and shape of the shoulder over time is small and good.

Example 2 60 parts of unsaturated polyester synthesized in Example 1,
10 parts of methacrylamide, 15 parts of tetraethylene glycol, 400 parts of polyethylene glycol, 15 parts of dimethacrylate, 0.7 parts of benzyl dimethyl ketal,
A photopolymerizable composition was prepared using 0.018 part of N-nitron phenylnaphthylamine and monothiol derivatives as shown in Table 2.

Next, a resin plate was prepared in the same manner as in Example 1, and the results are shown in Table 2. As a comparative example, the results obtained using 0.006 part of N-nitron phenylnaphthylamine without using the monothiol derivative are also shown in Table 2. From Table 2, when monothiol derivatives are used, the sensitivity is higher than in Comparative Example 2, which does not use monothiol derivatives.
It can be seen that the shape of the shoulder of the relief is large, and that the change in sensitivity over time is small and good.

Example 3 Unsaturated polyester 63 synthesized in Example 1
parts, acrylamide 8 parts, tetraethylene glycol dimethacrylate, polyethylene glycol 600, dimethacrylate 7 parts, diacrylphthalate 12 parts, benzyl ketal derivatives shown in the table below 1 part, 2-mercaptobenzaoxazole 0.03 part and N-nitroso A photopolymerizable composition was obtained using 0.015 parts of diphenylamine.

A resin plate was prepared from this in the same manner as in Example 1, and the results are shown in Table 3. Table 3 also shows the results obtained without using the benzyl ketal derivative as a comparative example. According to Table 3, when only the monothiol derivative is used without using the benzyl ketal derivative, there is no photocuring at all, but when both are used together, the sensitivity is high and the Yorda monomorphism is large, showing good results.

Claims (1)

[Claims] 1 a) The following general formula (1) as a photopolymerization initiator ▲ There are numerical formulas, chemical formulas, tables, etc. ▼... (1) [However, in the formula,
X is H, cl, alkyl group of C_1 to C_5, C_1 to
C_5 represents an alkoxy group, A represents a 6-membered aromatic group, R represents a C_1 to C_1_0 alkyl group, C_7 to C
Indicates the aralkyl group of ＿9 or the ▼ group with mathematical formulas, chemical formulas, tables, etc. Here, n is an integer from 2 to 5, m is an integer from 1 to 5, and R^1 is C
Indicates an aralkyl group of _1 to C_5. ] and b) an addition-polymerizable compound having an ethylenic double bond and a soluble polymer characterized by containing a heterocyclic monothiol derivative and/or an aromatic monothiol derivative. Polymerizable composition.