JPS6031322B2 - Highly sensitive photocurable composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides improved photosensitivity, stable shoulder shape moldability, and properties thereof by adding a specific photopolymerization initiator, a monothiol derivative, and an organic phosphite ester in combination. The present invention relates to a photocurable composition having storage stability.

In general, a resin composition consisting of a resin such as unsaturated polyester and an addition polymerizable compound having an ethylenic double bond,
By irradiating actinic rays in the presence of a photopolymerization initiator,
It is known that the composition can be photopolymerized to form a polymerized and crosslinked cured product, which is applied in the printing field as a photosensitive resin plate.

Conventionally, photopolymerizable compositions have a high photosensitivity during photopolymerization, and when printing using a photopolymerized printing original plate, there is little loss of the relief, giving a very stable shoulder shape of the relief. There has been a desire for a product that has good storage stability in terms of sensitivity and stable shoulder shape formation, ie, one that does not deteriorate over time in sensitivity and stable shoulder shape formation.

Although various studies have been conducted and various proposals have been made for this purpose, no practical proposal that satisfies these three requirements has yet been made. For example, even if a stable shoulder shape can be obtained by increasing the sensitivity, problems such as a significant decrease in sensitivity over time or poor storage stability and easy gelation may occur. On the other hand, it is extremely difficult to suppress the deterioration of sensitivity over time, and it must always be stored in an inert gas or sealed in a gas-barrier plastic container, glass, metal container, etc., making it completely impractical. It can be said that it is lacking in quality. JP-A-46-179 discloses that a total formulation consisting of a) penzoin ether, b') an organic ester of phosphorous acid, and b'') phosphine is cured by ultraviolet irradiation using as a photoinitiator. There are descriptions of the possible formulations, i.e. molding, bonding and coating materials.Here, the synergistic effect of the organic ester of phosphorous acid and phosphine on shortening the gelation time due to ultraviolet irradiation by the organic ester of phosphorous acid and phosphine is described. These effects alone are greater for phosphine than for organic wastes of phosphorous acid, and therefore it is thought that phosphine acts primarily; however, in combination with phosphine, it is highly toxic, especially to the nervous system, so it is not actually effective. The use of JP-A-50-117502 attempts to improve this drawback of photocurable compositions, as it requires very careful handling and is inconvenient in practical terms. Further, it is necessary to improve it (this was achieved as a result of intensive research). That is, the present invention is based on a benzoin alkyl ether' and the following general formula [1] [wherein X is day, cl, C, -C5 alkyl group, C, -C5 alkoxy group, A is a 6-membered aromatic group, R is C, -C, o alkyl group, C7-C9 aralkyl group, or ÷C elbow 2no Indicates mR' group.

However, n is an integer of 2 to 5, m is an integer of 1 to 5, R' is C,
~C5 alkyl group. ] A ketal compound represented by {one or more photopolymerization initiators selected from the group consisting of rho; b) a heterocyclic monotheol derivative and/or an aromatic monothiol derivative; and c) an organic compound having at least one aromatic group. The present invention relates to a highly sensitive photocurable composition mainly consisting of a soluble polymer and an addition polymerizable compound having an ethylenic double bond, which is characterized by containing a phosphoric acid ester.

Examples of the photopolymerization initiator a, which is the first component in the photocurable composition of the present invention, include penzoin methyl ether, benzoin ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, Examples include compounds (not necessarily produced by this method) corresponding to penzil represented by the following formula, in which one carbonyl group is converted to a ketal, such as penzil represented by the following formula. In addition to dimethyl ketal, penzyl ketal, benzyl dipropyl ketal, benzyl di(B-phenylethyl) ketal, benzyl di(2-
methoxyethyl) ketal, benzyl (2-ethoxyethyl) ketal, benzyl (2-ethoxyethoxyethyl) ketal, benzyl (2-ethoxyethoxyethyl) ketal, 4,4'-dimethylbenzyl dimethyl ketal, 2,2 Examples include '-dimethoxybenzyrudiethyl ketal, 4,4'-dichlorobenzyrudiethyl ketal, 4,4-dichlorodipropyl ketal, and the like.

Among the compounds of the above a, ketal compounds represented by the general formula (1) are particularly preferred, and among them, penzyl dimethyl ketal, benzyl diethyl ketal, benzyl di(2-methoxyethyl) ketal, and 4,4'-dimethyl ketal are particularly preferred. preferable. These photopolymerization initiators may be used alone or in combination of two or more. These photopolymerization initiators are usually used in an amount of 0.01 to 100 parts by weight of the photocurable composition.
It is used in a proportion of 10.0 parts by weight. Next, examples of the compound b as the second component include the following examples of heterocyclic monothiol derivatives.

2-mercaptobenzothiazole, a derivative of 2-mercaptobenzothiazole whose nucleus is substituted with an alkyl group such as a methyl group, an ethyl group, an isopropyl group, and/or a nitro group, a halogen atom, etc.; 2-mercaptobenzoxazole: a methyl group , 2-mercaptobenzoxazole derivatives whose nucleus is substituted with an alkyl group such as ethyl group, isopropyl group, and/or nitro group, halogen atom, etc.; 2-mercaptobenzimidazole; methyl group, ethyl group, isopropyl group, phenyl group, etc. A derivative of 2-mercaptobenzimidazole substituted with N; a derivative of 2-mercaptobenzimidazole substituted with an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a nitro group, or a nucleus such as a halogen atom; Mercaptothiazole; 2-mercatimidazole; methyl group, . Examples include 2-mercaptimidazole N-substituted with an ethyl group, isopropyl group, or phenyl group, and derivatives of metal salts such as sodium, potassium, calcium, and zinc of the above-mentioned heterocyclic monothiol derivatives.

Among these, preferred are 2-mercaptobenzoazole and its metal salts, 2-mercaptobenzooxizole and its metal salts; 2-mercaptoimidazole and 2-mercaptoimidazole and 2-mercaptotimidazole and 2-mercaptobenzoazole and 2-mercaptotimidazole whose nucleus is substituted with an alkyl group, a nitro group, a halogen atom, etc. 〆Captoimidazole derivatives; 2-mercaptobenzoxazole derivatives substituted with N by an alkyl group, a vinyl group, etc., and metal salts thereof, etc. can be mentioned.

The following examples of aromatic monothiol derivatives can also be given.

thiophenol, 2-nitrothiophenol, 2,4-dinitrothiophenol, 8-thionaphthol, thiosalicylic acid, aliphatic or aromatic ester of thiosalicylic acid,
Examples include aliphatic or aromatic diesters of 4-mercaptobenzoic acid, thiosalicylic acid, and metal salts of mercaptobenzoic acid such as sodium, potassium, calcium, and zinc. Among these, preferred are nitrothiophenol, thiosalicylic acid, and the like.

These may be used alone or in combination of two or more.

Compared to the above monothiol derivatives, trilene-2.4
- Dithiols, lauryl mercaptan, etc. and polythiols do not have a good effect on the storage stability with respect to gelation of photopolymerizable compositions, and compositions containing them are prone to gelation. The amount of the above monothiol derivative used is 0.001 to 5 parts by weight based on 10 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 compatibility with the composition becomes insufficient. Next, the following compounds can be cited as examples of the compound c as the third component.

Examples include tri-p-(nonyl phenyl) phosphite, tri-p-toluyl phosphite, triphenyl phosphite, diphenyl decyl phosphite, and monophenyl didecyl phosphite. These organic phosphorous acid esters may be used alone or in combination of two or more.

In addition, these are usually used in an amount of 0 per 100 parts by weight of the photocurable composition.
．． It is used in a proportion of 0.01 to 10.0 parts by weight. These organic phosphite esters bring about the effects of the present invention only when used in combination with monothiol derivatives, and cannot exhibit almost any effect when used alone. 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 rays in the presence of a photopolymerization initiator. It is a compound that can be used.

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 either liquid or solid at room temperature. Therefore, depending on the properties of the soluble polymer and the amount used, the composition may represent the entire composition or may represent a solid state.
Regardless of the particularity of the present invention, the effects of the present invention can be expected in any case. Furthermore, it is more preferable that the soluble polymer used 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 monoesters such as acrylic acid, methyl acrylate, ethyl acrylate, ethyl acrylate, lauryl acrylate, and phenyl acrylate; ethylene glycol acrylate, polyethylene glycol di Diacrylate esters of glycols such as acrylate, propylene glycol diacrylate, and polypropylene glycol acrylate; triacrylate esters of triols such as glycerintoacrylate and trimethylolpropane triacrylate; and polyacrylate esters of polyols;
and methacrylates corresponding to these, and further acrylamide, methacrylamide, N-methylolacrylamide, diacetone acrylamide, N,N
Acrylamide derivatives such as -methylenevinacrylamide and N-ptoxymethylacrylamide; vinyl acetate, styrene, vinyl toluene, diallyl phthalate, diallyl isophthalate, triallyl cyanurate,
etc. can be given.

These addition polymerizable compounds having an ethylenic double bond can be used alone or in combination of two or more.

In addition, 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 precurable composition of the present invention to improve the physical properties after curing, and a plasticizer or the like may be added 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 and hydrocarbons include Yangs, quinones, amines, and N-nitrosamines.
Particularly preferred are nitrosamines. These storage stabilizers have little effect on the photocuring reaction rate, and are added only in the amount necessary to suppress or prevent reactions caused by heat during storage, and the amount is 0 to 100 parts by weight of the photocurable composition. .001
-1.0 parts by weight. The photocurable composition of the present invention can be obtained by thoroughly mixing the above-mentioned components.

When the composition is solid, it may be formed into a sheet by dissolving it in a solvent and then forming it into a sheet, or by hot rolling or rolling. Either of them can be used as a photosensitive material by coating and adhering them to a support such as a metal plate such as aluminum or iron plate, or a plastic sheet such as polyethylene terephthalate. Furthermore, even when the composition is in liquid form, it can be used by coating it on a support in the same manner. In order to use the photocurable composition of the present invention for producing a printing original plate, iron, steel plate,
A metal plate such as aluminum, a rubber sheet such as natural rubber or synthetic rubber, or a plastic sheet such as polyethylene terephthalate is used as a support, and a photocurable composition is applied on the support.
It is expedient to apply it in layers with a thickness of 2 to several millimeters.

The layer is preferably adhered to the support via an adhesive layer if necessary. Next, the photocurable composition is cured by irradiating actinic rays through a negative film or a positive film having a line portion. The time required for this photocuring, that is, the exposure time, is usually from several minutes to more than ten minutes, but when the curable composition of the present invention is used, this time is significantly shortened due to its high sensitivity. The shoulder shape is a trapezoid with a widening hem, that is, Mt. Fuji shape, and can withstand sufficient suppression and can form a leaf. The light source for exposure includes
Depending on the properties of the photocurable composition, tungsten bulbs, xeno lamps, mercury lamps, chemical fluorescent lamps, etc. can be used.
It is preferable to use active light that emits active rays rich in ultraviolet rays for up to 70 hours.

The non-image areas exposed to light are removed with a dilute alkaline aqueous solution (eg, soda carbonate, caustic soda aqueous solution), an organic solvent, or the like. Then, by drying, a printing original plate having tough leaves is obtained. When producing a printing original plate using the photocurable composition of the present invention, the sensitivity is higher than that of conventional photocurable compositions, so the exposure time is significantly shortened, so that the process of obtaining the printing original plate can be reduced. It saves time and greatly improves productivity.

In addition, the sensitivity of the photocurable composition and the changes over time in the shoulder shape of the relief are reduced and improved compared to conventional compositions, which is extremely advantageous in actual use. Furthermore, the shoulder shape of the photocurable relief obtained from the photocurable composition is extremely stable, that is, the adhesive area of the base of the relief with 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 process, and eliminates relief defects such as falling off and folding of the relief. When the curable composition of the present invention is cured by irradiation with actinic rays, the cured relief has a tensile strength of 100k9/ or more and a Shore hardness (
D scale) of 50 degrees or more, it has excellent dimensional stability, and has good swelling resistance against organic solvents such as alcohol, acetone, and benzene, so it can faithfully reproduce delicate lines. It is useful as an original plate for precision printing and color printing. The photocurable 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 flexographic plates.

The present invention will be explained in detail below using examples.

In the examples, "part" 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 and Comparative Examples 1 to 4 174 parts of fumaric acid, 58 parts of trimellitic anhydride, 175 parts of adipic acid, 223 parts of diethylene glycol, and 8 parts of dipropylene glycol were mixed in a nitrogen atmosphere at 100 to 100 parts.
0 in 2000. The reaction was then carried out at 190° C. for 4 hours to obtain an unsaturated polyester with an acid value of 130.

65 parts of the unsaturated polyester and 1 part of methacrylamide thus obtained. A mixture consisting of 25 parts of pyrene glycol dimethacrylate, a photopolymerization initiator of the kind and parts as shown in Table 1, a monothiol derivative,
A photocurable composition was prepared with a combination of an organic phosphite and a stabilizer. This was immediately subjected to exposure treatment for photopolymerization, polishing and removal of unexposed areas, and drying using the following method to obtain a resin plate for relief printing. That is, a negative film is placed on a glass slope installed horizontally, and a 12 micron thick polyethylene terephthalate film is closely stacked on top of it.
Further, the above braid was applied thereon to a thickness of 0.7 skin. Next, a 0.3-leg steel plate having an antihalation layer and an adhesive layer was placed on top of this composition, and a 60W ultraviolet light lamp 8 was placed on top of the composition.
The time required for a silk dot with a light yield rate of 4% on the negative film to adhere to the negative film surface using a light source made up of books (
This reciprocal number is referred to here as the sensitivity of the photocurable composition. ) was exposed. Next, the exposed areas were washed with a dilute alkaline aqueous solution and dried, and the relief of the resulting resin solution was sufficiently hard and strong. Sensitivity of the obtained light-forming composition, similder shape of the relief of an independent point with a diameter of 180 Buddhas (
Here, it is expressed as Sb/ST.

Here, ST is the area of the crown of the shirt, which corresponds to the area corresponding to the independent point of the negative film. Sb is the area corresponding to ST on the bushing surface between the leaf base and the support. Therefore, it can be said that the larger this value is, the more stable the shoulder shape of the relief is.) The results are shown in Table 1. Table 1 From Table 1, it can be seen that the combination of the photopolymerization initiator, monothiol derivative, and organic phosphite ester has a remarkable synergistic effect on sensitivity and shoulder shape.

Examples 2 to 4 67 parts of the unsaturated polyester synthesized in Example 1, 8 parts of methacrylamide, 1 part of diallyl phthalate, 7 parts of polyethylene glycol 400 dimethacrylate, and 8 parts of polypropylene glycol (molecular weight approximately 590) dimethacrylate. to a mixture consisting of;
Add 1.0 part of various photopolymerization initiators shown in Table 2, and then add 2 parts
-0.035 part of zinc salt of mercaptobenzimidazole, 0.3 part of monophenyldidecylphosphite and N
-0.02 part of nitrosodiphenylamine was added to obtain a photocurable composition.

A resin plate was prepared in the same manner as in Example 1 using the obtained photocurable composition and the product which was placed in an open container in a constant temperature dryer at 30 qo and aged. The results obtained are shown in Table 2. Table 2 Examples 5 to 7 63 parts of the unsaturated polyester synthesized in Example 1, 7 parts of methacrylamide, 15 parts of tetraethylene glycol dimethacrylate, 15 parts of polypropylene glycol (molecular weight approximately 300) monomethacrylate, N =
0.015 parts of tromphenylnaphthylamine and 0.7 parts of benzyl dimethyl ketal were added, and various monothiol conductors of types and amounts shown in Table 3 were added to obtain a photocurable composition.

Next, a resin plate was prepared in the same manner as in Example 2, and the results are shown in Table 3. Table 3 As shown in Table 3, the monothiol derivatives of the present invention exhibit remarkable effects, but both Comparative Examples 5 and 6 have poor storage stability and gelation, so they cannot be used in practice.

Claims (1)

[Claims] 1 a Benzoin alkyl ether (A) and the following general formula [I] ▲ Numerical formulas, chemical formulas, tables, etc. ▼ [However, in the formula, X is H, Cl, alkyl having 1 to 5 carbon atoms group or an alkoxy group having 1 to 5 carbon atoms, A is a 6-membered aromatic group, R is an alkyl group having 1 to 10 carbon atoms,
Aralkyl group having 7 to 9 carbon atoms or formula -(CnH_2
nO)-mR' (where n is an integer of 2 to 5, m is an integer of 1 to 5, and R' is an alkyl group having 1 to 5 carbon atoms). . ] One or more photopolymerization initiators selected from the group consisting of ketal compounds (b) represented by; b) a heterocyclic monothiol derivative and/or an aromatic monothiol derivative; and c) having at least one aromatic group A highly sensitive, photocurable composition mainly comprising an addition polymerizable compound having an ethylenic double bond and a soluble polymer, which is characterized by containing an organic phosphorous acid ester.