JPH0316017B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an image duplicating material using a photopolymerizable photosensitive resin. More specifically, the present invention relates to an image duplicating material that has excellent shelf life, excellent resolution of a reproduced image, transparency of white areas (non-image areas), and image adhesion. A photopolymerizable photosensitive resin is a composition mainly consisting of a polymeric binder, a photoinitiator, and a crosslinking agent.It has high photosensitivity and excellent physical properties after photocuring, so it has traditionally been used as a photosensitive resin letterpress material. It has been widely used as. A photosensitive resin letterpress material is a material in which a photopolymerizable photosensitive resin is laminated to a thickness of several hundred micrometers on a support (plastic film or metal plate) having an adhesive layer, and further has a cover film. . In this case, the image obtained after processes such as exposure and development is a relief image with irregularities of several hundred micrometers, which is used for printing. The adhesive layer must have the ability to firmly bond the support and the relief image, and usually has a thickness of 10 to 30 μm and is made of a partially cross-linked polymer layer. There is. For example, the most typical adhesive layer for photosensitive resin letterpress printing consists mainly of a saturated polyester adhesive and a small amount of a polyfunctional isocyanate. By the way, silver halide films that use expensive silver are currently being used as high-precision image duplication materials, particularly for applications such as return lithography films in photolithography processes and photo tools in printed circuit board manufacturing processes. However, if the above-mentioned highly sensitive photopolymerizable photosensitive resin could be used as a substitute for this silver salt film, it would be very economical, save limited resources, and greatly contribute to the industry. In order to use this photopolymerizable photosensitive resin as a high-precision image duplication material, it is simply necessary to strengthen the adhesion between the image and the support, and to increase the thickness of the photosensitive resin layer of the photosensitive resin letterpress material. A thin film of several microns to several tens of microns is sufficient. However, when attempting to obtain high-precision image duplicating materials, it appears that precise images can be obtained at first glance, but upon closer examination, the following fatal flaws are found. 1. The shelf life of the image duplication material itself is very short. 2 The formed image lacks transparency in non-image areas (white areas). (What is transparency here?
It does not simply refer to apparent transparency, but also includes the ultraviolet absorption spectrum, that is, when annealing the same image duplication material based on the obtained image, the active ray region of the same material It also means transparency. ) Since such defects are fatal to both the commercial reliability (shelf life) and value (returnability) of image reproduction materials,
Such defects are a phenomenon specific to photopolymerizable photosensitive resins that contain a large amount of low molecular weight components, so when developing thin-film image duplicating materials using photopolymerizable photosensitive resins, we have This suggests that a completely different design from resin letterpress materials is required. The present inventors investigated various causes of the defects and found that low molecular weight components such as a photoinitiator and a crosslinking agent in the photopolymerizable photosensitive resin composition migrate into the adhesive layer. Changes occur in the composition and the original performance (sensitivity, developability, etc.) cannot be maintained;
Furthermore, they discovered that this change occurred in a fairly short period of time, and in order to eliminate these causes, they conducted extensive research and finally completed the present invention. That is, the present invention provides an adhesive layer on a support,
In an image duplicating material having a photopolymerizable photosensitive resin layer with a thickness of 20 μm or less thereon, the adhesive layer has a hydroxyl group having a hydroxyl value of 20 to 200 mgKOH/g and a carboxyl group having an acid value of 20 to 250 mgKOH/g. The image reproduction material is mainly formed from a cellulose derivative having a group and a polyfunctional isocyanate, and is characterized in that the ratio of isocyanate group equivalent to the sum of hydroxyl group equivalent and carboxyl group equivalent is 0.3 to 2.5. The support in the present invention is mainly a plastic film, and includes films of polyester, polypropylene, polyethylene, polyvinyl chloride, polyvinylidene chloride, polycarbonate, cellulose acetate, etc.
The axially stretched polyester (polyethylene terephthalate) film has excellent dimensional stability and transparency, and can maximize the effects of the present invention. There is no strict limit to the thickness of the support, but 75~
125μ is appropriate. In addition, although only transparent plastic films have been mentioned in the above example, application of the present invention to paper, metal plates, etc. coated with plastic is one application example of the present invention. Further, such plastic film may be subjected to surface modification treatment such as corona treatment, plasma treatment, physical or chemical treatment, etc., in order to improve the adhesion with the adhesive layer. The photopolymerizable photosensitive resin in the present invention mainly consists of a polymeric binder, a photoinitiator, a crosslinking agent (a monomer or oligomer having an ethylenically unsaturated bond), and in addition, stabilizers and plasticizers as necessary. , a surfactant, a coloring agent, etc. However, the present invention is also particularly effective for those containing a so-called actinic ray absorber. This is because the effect of the present invention is to prevent the diffusion of low molecular weight photoinitiators, crosslinking agents, etc. into the adhesive layer, and this is particularly true in systems containing such actinic light absorbers in terms of opaque photosensitive layers. This is because changes caused by, for example, a decrease in sensitivity are significant. Examples of the polymer binder, crosslinking agent, and actinic ray absorber used in the present invention are listed below. a. Polymer binder The binder must be an organic polymer that is soluble in a solvent and solid at temperatures below 50°C, and must be compatible with the polymerizable monomer. The binder may or may not be thermoplastic, but it must have film-forming ability, and in particular it must have film-forming ability even when a crosslinking agent and photoinitiator are added. Examples of such binders include derivatives of cellulose esters and ethers (cellulose ethyl ether, cellulose acetate, carboxymethyl cellulose, cellulose acetate succinate, cellulose methyl ether phthalate, cellulose methyl ether succinate, etc.); Polyalkyl ethers, polyesters, polyamides, polyvinyl esters and their copolymers, phenolic resins, polyvinylidene compounds, polyvinyl alcohols, gelatin and its derivatives, polyvinyl butyral, polyacrylamide, polyvinylpyrrolidone, polystyrene, chlorinated rubber , polyethyleneimine, etc. Particularly, in order to enable development with an aqueous developer, the binder itself must be dissolved or dispersed in the aqueous developer. Examples of such polymers include polyvinyl alcohol, polyacrylamide, sulfone groups, acid-quaternized units of tertiary nitrogen-containing polymers, polymers containing carboxyl groups, polyvinylpyrrolidone, polyethyleneimine, and the like. Examples of binders soluble in acidic or alkaline aqueous solutions include carboxyl group-containing cellulose derivatives such as carboxymethyl cellulose, cellulose methyl ether phthalate, and cellulose methyl ether succinate, methacrylic acid, acrylic acid, maleic acid, itaconic acid, and crotonic acid. Examples include copolymers of vinyl monomers, polyesters containing tertiary nitrogen groups, polyamides, polyethers, and polyvinyl polymers. Note that the main chain or side chain of the binder may contain a polymerizable unsaturated double bond group. b Photoinitiator A photoinitiator has the ability to initiate a polymerization reaction or a crosslinking reaction with actinic rays, and is used alone or in combination with other compounds. Examples of typical compounds include benzyl, benzophenone,
Michler's ketone, benzophenone derivatives such as 4,4'-bis(diethylamino)benzophenone, 4-methoxy-4'-dimethylaminobenzophenone, anthraquinone, 2-chloroanthraquinone, 2ethylanthraquinone, 1-chloroanthraquinone, Aromatic ketones such as phenanthraquinone, benzoin, benzoin alkyl ethers, benzoin derivatives such as α-methylbenzoin, benzyl dimethyl ketal, polynuclear quinones, 2,4,5-triaryl imidal dimer and There are combination systems of free radical generators, etc. Furthermore, the sensitivity can be further improved by adding a sensitizer or a sensitizing dye. In addition, the 2,4,5-triarylimidazole dimer includes 2-(0-methoxyphenyl)-4,
5-diphenylimidazole dimer, 2-(0-
triphenylimidazole dimers such as chlorophenyl)-4,5-diphenylimidazole dimer, 2-(p-methylmerocaptophenyl)-4,5-diphenylimidazole dimer, 2-(1
-naphthyl)-4,5-diphenylimidazole dimer, 2-(9-anthryl)-4,5-diphenylimidazole dimer, 2-(2-methoxy-
1-naphthyl)-4,5-diphenylimidazole dimer, 2-(2-chloro-1-naphthyl)-
Polycyclic aryl-4,5-diphenylimidazole 2 such as 4,5-diphenylimidazole dimer
Quantities can be mentioned. The free radical generator used in combination with the 2,4,5-triarylimidazole dimer includes:
p-aminophenyl ketone compounds such as p,p'-bis(dimethylamino)benzophenone; leucotriphenylmethane dyes such as leucomalachite green and leuco crystal violet; 2.
Cyclic diketone compounds such as 4-diethyl-1,3-cyclobutanedione, thioketone compounds such as 4,4'-bis(dimethylamino)thiobenzophenone, mercapun compounds such as 2-mercaptobenzothial, N-phenyl Glycine, dimedone, 7-diethylamino-4-methylmarine, etc. can be mentioned. As the sensitizer or the sensitizing dye, xanthene-based, acridine-based, thiazine-based, cyanine-based dyes and the like are effective. c Crosslinking agent The crosslinking agent used may have one or more polymerizable double bonds. Examples of such compounds include alkyl acrylates or alkyl methacrylates such as hexyl acrylate, hexyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, lauryl acrylate, lauri methacrylate, benzyl acrylate, benzyl methacrylate, hydroxyalkyl acrylate,
Hydroxyalkyl methacrylate, N-N-
dialkylaminoalkyl acrylates or methacrylates, alkyl ether acrylates or methacrylates such as methoxyethyl acrylate, ethoxyethyl methacrylate, halogenated alkyl acrylates or methacrylates, alkylacrylic or methacrylamides, hydroxyalkyl acrylates or methacrylates, Acrylates or methacrylates of polyalkyl ethers such as diethylene glycol diacrylate or methacrylate, triethylene glycol diacrylate or methacrylate, ethylene glycol diacrylate or dimethacrylate, polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol Acrylates or methacrylates, acrylic acid,
A reaction product of methacrylic acid, glycidyl acrylate or methacrylate with an active hydrogen-containing substance,
Examples include reaction products of glycidyl compounds and acrylic acid or methacrylic acid, condensates of N-methylol compounds and urea compounds, and reaction products of polyisocyanate compounds and hydroxyalkyl acrylates or methacrylates. The crosslinking agent used is 1
It is not limited to the type, but it is necessary to select the crosslinking agent to be used depending on the type of binder, the ratio of crosslinking agent, the type and amount of photoinitiator, etc. Determined based on gender, photosensitivity, etc.
If the boiling point of the crosslinking agent used is low, it will volatilize and decrease during or after film formation, so a high boiling point is desirable. d Actinic ray absorber By adding, in addition to the photoinitiator, a compound effective in absorbing actinic rays, an image that is opaque to actinic rays can be formed. By increasing the absorption of actinic rays, in the image area exposed through the transparent part of the mask, only the upper layer undergoes a curing reaction, while the lower layer remains uncured. In this way, if the uncured lower layer can be maintained, the force reducing property, which is an advantageous characteristic for use as a plate-making film, can be maintained. On the other hand, if the absorption amount of actinic rays is small, even the lower layer will be hardened during exposure, making it impossible to reduce the force later. Furthermore, if the amount of actinic rays absorbed is too large, only the very thin upper layer can be cured, resulting in not only poor resist effect but also poor photosensitivity. The most preferable photosensitive layer has an actinic ray absorbance of 1.5 to 4. Actinic light absorbers used include ultraviolet absorbers, ultraviolet absorbing dyes, and other dyes and pigments. Examples of these are carbon black,
Titanium oxide, iron oxide, various metals and metal oxides,
Powder of compounds such as sulfides, pigment black (C.1.50440), chrome yellow light (C.1.77603), 2,2'-dihydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone hydroxyphenyl Benzotriazole, 2-(2'-hydroxy-5'-methoxyphenyl)benzotriazole, resorcinol monobenzoate, ethyl-2-cyano-3,3-diphenyl acrylate, toluidine yellow GW
(CI71680), Molybdenum Orange (CI77605),
These include Sudan Yellow (C.1.30) and Oil Orange (C.1.12055). In particular, carbon black is desirable in order to achieve the same black color as conventional silver salts.
Furthermore, if a non-colored ultraviolet absorber is used, it is better to add dyes or pigments since the image area will be difficult to see. In the case of inorganic/organic pigments and metal compounds, it is necessary to make them into fine particles by physical or chemical methods. In the present invention, the thickness of the photosensitive resin layer having the above composition is 20 μm or less. This does not mean that the present invention is not effective for materials with a thickness exceeding 20 μm, but rather that the present invention is overwhelmingly advantageous over other techniques for image duplicating materials that use a photosensitive resin layer of 20 μm or less. It is effective. Next, the adhesive layer used in the present invention will be described. This mainly consists of cellulose derivatives having a hydroxyl group with a monohydroxyl value of 20 to 200 mgKOH/g and a carboxyl group with an acid value of 20 to 250 mgKOH/g (here, g means 1 g of cellulose derivative) and dipolyfunctional isocyanates. It is a component, and is blended so that the ratio of isocyanate group equivalent to the sum of hydroxyl group equivalent and carboxyl group equivalent is 0.3 to 2.5. Examples of the cellulose derivatives having hydroxyl and carboxyl groups include hydroxypropyl methylcellulose phthalate, hydroxyethyl methylcellulose phthalate, hydroxypropylmethylcellulose succinate, hydroxypropylmethylcellulose acetate succinate, hydroxypropylmethylcellulose hexahydrophthalate, and hydroxypropylmethylcellulose. Examples include malate. In such cellulose derivatives, if the hydroxyl value of the hydroxyl group and/or the acid value of the carboxyl group are each less than 20 mgKOH/g, the strength of the adhesive layer itself becomes weak, resulting in a decrease in adhesive strength or development Since the resistance to solvents such as liquids is greatly reduced, it causes various problems such as a decrease in resolution. Conversely, the hydroxyl value of the hydroxyl group is
If it exceeds 200 mgKOH/g or/and the acid value of the carboxyl group exceeds 250 mgKOH/g, the pot life of the adhesive layer solution for coating will be shortened and it will not be practical, and the polarity of the cleaner etc. of the formed image will be reduced. There are negative effects such as poor resistance to solvents. The polyfunctional isocyanates mentioned in the present invention are those having at least two or more isocyanate groups in the molecule, and examples of such products include monomeric isocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate. , aromatic isocyanates such as triphenylmethane triisocyanate, aliphatic isocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, and lysine diisocyanate. Furthermore, isocyanates obtained by modification with such monomeric isocyanates, for example, adducts with polyhydric alcohols such as trimethylolpropane, urethane-modified products, allophanate-modified products, biuret-modified products, isocyanurate-modified products, carbodiimide-modified products body, also dimer and 3
There are polymerized polyisocyanates. Further examples include prepolymers from polyether polyols such as tetramethylene ether glycol and polypropylene glycol. Blocked isocyanates obtained from the above isocyanates using phenols, oximes, lactams, etc. as blocking agents are also effective. The blending ratio of the polyfunctional isocyanate and the cellulose derivative is the ratio of the isocyanate group equivalent to the sum of the hydroxyl group equivalent and carboxyl group equivalent, that is, [-NCO]/[-OH]+[-
COOH] must be in the range of 0.3 to 2.5. This ratio range is necessary to fully exhibit the effects of the present invention, and if it is less than 0.3, the adhesive layer will not have sufficient adhesion to the plastic film and photosensitive resin layer, resulting in a decrease in resolution. Also, resistance to film cleaners etc. decreases. On the other hand, if this ratio exceeds 2.5, it is not preferable because not only the pot life of the coating adhesive layer solution decreases but also the performance of the photosensitive resin layer changes (developability, etc.). In the present invention, in addition to the above-mentioned cellulose derivatives and polyfunctional isocyanates, catalysts generally known as isocyanate reaction catalysts, such as di-n-butyltin dilaurate, dimethyl 2
Organometallic compounds such as tin chloride, stannath octoate, trimethyltin hydroxide, tetra-n-butyltin, cobalt naphthenate, iron acetylacetonate, 1,4-diazabicyclo(2,2,
2) Octane, N,N-dimethylcyclohexylamine, N,N,N',N'-tetramethylpropylenediamine, N-ethylmorpholine, N,N-
Amines such as dimethylethanolamine, 1,8-diaza-bicyclo[5,4,0]undecene-7 and salts thereof can be blended. The preferred blending range of the catalyst is 0.01% to 10% by weight relative to the solid content of the adhesive layer. This is because if it is less than 0.01% by weight, the effect as a catalyst is low, and if it exceeds 10% by weight, no significant increase in the effect can be expected. The cellulose derivative, polyfunctional isocyanate, and optionally a catalyst, which are the compositions of the adhesive layer described above, are usually in the form of a solution, coated on a support and dried to form the adhesive layer. The solvent that can be used at this time may be any solvent as long as it can dissolve the composition and form a film, and ketones such as acetone and methyl ethyl ketone, and cyclic ethers such as dioxane and tetrahydrofuran are particularly preferred.
These may be used in combination with other solvents or nonsolvents. Further, the preferable range of the thickness of the adhesive layer in the present invention is 0.1μ to 10μ. If it is thinner than 0.1μ, sufficient adhesive strength cannot be expected; conversely, if it is thicker than 10μ, some decrease in shelf life is observed even when using the structure of the present invention, and white areas This is not desirable as contamination has also been observed. The method for producing the image reproduction material of the present invention includes:
A solution of the cellulose derivative having the composition described above, a polyfunctional isocyanate and, if necessary, a reaction catalyst is coated on the support, and then dried by heating. Thereafter, the photopolymerizable photosensitive resin can be melt-formed or solution coated, followed by drying. In addition, since the photoreaction of photopolymerizable photosensitive resins is inhibited by oxygen, usually a cover film with good light transmission and removability or a protective layer soluble in the photosensitive resin solvent is added on top. establish. As the cover film or protective layer, for example, resins such as polyvinyl alcohol, polyacrylic acid, methyl cellulose, etc. can be used. In particular, polyvinyl alcohol is preferred because it has excellent oxygen barrier properties and can reduce the radical polymerization inhibiting effect caused by oxygen. As described above, since the image duplicating material of the present invention has the above-described structure, it has the following features. (1) Changes in sensitivity, developability, etc. are extremely small over a long period of time, and a product exhibiting stable shelf life can be obtained. 2. Since there is no contamination in the white areas of the formed image, the image not only has excellent contrast but also
Using this image, a large number of duplicated images can be obtained with the same accuracy even after repeated duplication. 3 The adhesive layer in the present invention exhibits excellent adhesion to both the photosensitive resin layer and the support, so the reproduced image exhibits high resolution, has excellent ability to reproduce fine halftone images, and has no adhesive tape attached to the image. It can withstand the normal retouching process of pasting and rapid peeling, and no peeling of halftone dots or other images is observed. 4 The adhesive layer in the present invention remains on the plastic film as white areas even after image duplication, but it is highly resistant to film cleaners and the like that are often used when handling duplicated images, and can be easily cleaned with cleaners. There is no image damage. The present invention will be specifically described below with reference to Examples. In the examples, parts simply mean parts by weight. Example 1 A 100μ thick polyester film was coated with the composition shown in Table 1 using a river coater.
A polyester film having an adhesive layer of 0.5 μm was prepared by heating and drying at 130° C. for 5 minutes. Next, a photosensitive composition was prepared by mixing and dispersing the following compositions, and each of the photosensitive compositions was coated on the polyester film provided with the adhesive layer using a reverse coater and dried to form a photosensitive layer having a thickness of 3 μm. Copolymer of methyl methacrylate (77 mol%) and methacrylic acid (23 mol%) 41 parts carbon black 12 parts trimethylolpropane triacrylate
34 parts 2-(2-chloro-1-naphthyl)4,5-
Diphenylimidazole dimer 8 parts Hydroquinone monomethyl ether 0.03 parts Dimedone 3 parts Michler's ketone 2.0 parts Methyl alcohol 140 parts Chloroform 120 parts Ethyl acetate 80 parts Image duplicating materials Nos. 1 to 4 having a protective layer having a thickness of 1 μm were prepared by similarly coating the protective layer composition and drying. Polyvinyl alcohol (degree of saponification 98.5%, degree of polymerization 500) 5 parts Neugen EA-140 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name) 0.2 parts Methyl alcohol 5 parts Water 90 parts The obtained image duplication material was subjected to 21 steps. A test negative film consisting of a guide (manufactured by Dainippon Screen Co., Ltd.) and a 300/inch, 5% pitch image with a dot area ratio of 5% to 95% was overlaid, and a bright room printer (manufactured by CRC Co., Ltd.) was used. Image exposure was performed for 15 seconds. Next, after removing the protective layer by washing with water, it was immersed in an aqueous solution of 1.2% Na ₂ CO ₃ adjusted to 30°C for 10 seconds, developed while rubbing with a sponge under washing, and then dried to form a reversed image. I got a film. A similar process is applied after each image reproduction material is manufactured.
The tests were carried out on samples from the 1st week and the 4th week. The results were judged as follows. 1 Photosensitivity: Number of curing stages of the 21st stage step guide 2 Shelf life: Comparison of the above photosensitivity after 1 week and 4 weeks 3 White area contamination: Absorbance at wavelength 375 mμ of the white area was measured using Hitachi 320 spectroscopy Measured with a photometer 4. Dot reproducibility: Ratio of halftone dots with partial defects to all halftone dots (%) 5. Adhesive strength: Sellotape 1.7 cm x 1.7 cm on the halftone dot image surface
Presence or absence of halftone dot loss when peeled vertically after adhering to 10cm size

[Table] Comparative Example 1 In order to more clearly demonstrate the effects of the present invention, image duplication material sample No. 5 was prepared in exactly the same manner as in Example 1, except that an adhesive solution with the following composition was used. Evaluations were conducted in the same manner. Vylon 20S (saturated polyester adhesive manufactured by Toyobo Co., Ltd., trade name) 50 parts Coronate L 4 parts U-Cat SA-No. 102 0.1 part Toluene 80 parts Methyl ethyl ketone 20 parts The obtained results are also listed in Table 2.

【table】

[Table] As is clear from Table 2, the image duplication material of the present invention has a long shelf life, no contamination in white areas, good image reproducibility, and the formed image is It can be seen that it is not easily damaged even by physical peeling action.

Claims (1)

[Claims] 1 An adhesive layer is provided on the support, and a thickness of
In an image duplicating material having a photopolymerizable photosensitive resin layer of 20 μm or less, the adhesive layer has a hydroxyl value of 20 to 20 μm.
200mgKOH/g hydroxyl group and acid value 20-250
An image reproduction characterized in that it is mainly formed from a cellulose derivative having a carboxyl group of mgKOH/g and a polyfunctional isocyanate, and the ratio of the isocyanate group equivalent to the sum of the hydroxyl group equivalent and the carboxyl group equivalent is 0.3 to 2.5. material.