JPS6130261B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electronic copying material for offset printing plates having excellent printability. A copying material for an offset printing plate is one in which the back side of a support is subjected to conductive treatment, an intermediate layer is provided on the back side, and a photoconductive layer made of photoconductive powder and an insulating resin is provided on the intermediate layer side. This copying material obtains an electrostatic latent image by ordinary electrophotography, forms an image by dry or wet development, and then treats the non-image areas with a desensitizing liquid to be used for printing as an offset mer star plate. be done. Therefore, in order to obtain good printed matter, the original image must first be faithfully reproduced on the offset printing plate, and it must also be compatible with the desensitizing treatment liquid, be water resistant, and be able to retain the image during printing. It is necessary for the photoconductive layer to have properties such as not peeling off. However, these performances are significantly affected by the insulating resin in the photoconductive layer, and the conventionally used silicone resins, alkyd resins, or carboxylic acid-containing acrylic polymers do not provide satisfactory performance, so offset printing is used. It is desired to develop an excellent binder for printing plates. Therefore _, the inventors of the present invention are currently conducting studies with the aim of developing electronic copying materials for offset printing plates that can meet the above-mentioned needs.General formula -OOCR ₁ COOH

【formula】

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【Formula】Also teeth

R ₂ and R ₃ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The present invention was completed based on the discovery that an electronic copying material for offset printing plates, which has a photosensitive layer containing a resin containing a specific amount of groups represented by the following formula as a binder, can achieve the object. The gist of the present invention is offset printing characterized by providing a photosensitive layer mainly composed of a resin containing a group represented by the general formula [] in a proportion of 0.5 to 60% by weight and photoconductive powder. It is in electronic copying materials for printing plates. It is necessary that the resin [A] used in carrying out the present invention contains a group represented by the general formula [] in a proportion of 0.5 to 60% by weight, and this content is less than 0.5% by weight. A photosensitive layer using a resin as a binder has poor sensitivity, and when a copied image is formed, the image density is so low that it is not practical. If the photosensitive layer is used as a printing agent, there will be a lot of fog in the copied image, making it impossible to produce a good original printing plate. The resin used in the present invention is a resin composed of a single polymer or a resin composed of a mixture of two or more kinds of polymers, and can be produced as follows. (a) For hydroxyl groups in copolymers of aromatic vinyl monomers such as styrene, α-methylstyrene, α-chlorostyrene, and vinyltoluene with allyl alcohol and methallyl alcohol. (In the formula, R ₁ has the same meaning as above) is added to an acrylic resin so that the content of the group represented by the general formula [] is 0.5 to 60% by weight. How to adjust. (b) bidroxyalkyl esters and acrylates of α/β-monoethylenically unsaturated carboxylic acids;
By subjecting the hydroxyl group in the copolymer with methacrylate, an aromatic vinyl monomer, and other copolymerizable monomers to an addition reaction with a carboxylic acid anhydride represented by the general formula [], the general formula [] The content of groups represented by 0.5 to 60% by weight
A method of making resin adjusted to (c) General formula (In the formula, R ₁ , R ₄ and R ₆ have the same meanings as above) and an acrylate;
A method of copolymerizing methacrylate, an aromatic vinyl monomer, and other copolymerizable vinyl monomers such that the content of groups represented by the general formula [] is 0.5 to 60% by weight. Approximately three methods as described above can be used to introduce a group represented by the general formula [] into the polymer constituting the resin [A] of the present invention. Specific examples of carboxylic acid anhydrides or ring-opened products thereof include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, naphthylic acid, diphenic acid, isodiphenic acid, biphenyl-4,4'-dicarboxylic acid, citraconic acid, and pyrosincone. Mention may be made of the acids maleic acid, methylmaleic acid, fumaric acid, aconitic acid, citraconic acid, tetrahydrophthalic acid, itaconic acid and their anhydrides. A specific example of the hydroxyalkyl ester of α/β-monoethylenically unsaturated carboxylic acid used as a starting material when carrying out the above production method (b) is the following formula: (In the formula, R ₄ and R ₆ have the same meanings as above) (In the formula, R ₅ is a group selected from an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, and a benzyl group,
R ₆ has the same meaning as above, and n represents an integer of 1 or 2. ) Compounds represented by the formula [] include acrylic acid, methacrylic acid and ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, 2-ethylhexylene glycol, polyethylene glycol, polypropylene glycol, etc. Compounds represented by the formula [] are monoesters of itaconic acid or α-methyleneglutaric acid and the above-mentioned diols, or alkyl esters of monohydroxyitaconate or α-methyleneglutaronate. It is a type of chemical compound. In addition, methacrylates, which serve as other starting materials,
Specific examples of acrylates include alkyl groups such as methyl, ethyl, n-butyl, sec-butyl, and t-butyl.
Mention may be made of acrylates or methacrylates such as butyl, n-propyl, sec-propylhexyl, cyclohexyl, pentyl, heptyl, octyl, 2-ethylhexyl, lauryl, stearyl, perfluoroalkyl, etc.
Specific examples of other copolymerizable monomers include styrene, α-methylstyrene, α-chlorostyrene,
Examples include aromatic vinyl monomers such as vinyltoluene, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinyl chloride, vinylidene chloride, α-methyleneglutaronitrile, vinyl acetate, vinyl propionate, and the like. Specific examples of the compound represented by the formula [] used as a starting material when manufacturing the resin used in the present invention by the above manufacturing method (c) include hydroxyalkyl acrylate or methacrylate represented by the general formula [] and the compound represented by the general formula []. ] or glycidyl acrylate or methacrylate with the formula
Examples include ring-opened carboxylic acid anhydride products and α-monoesterified products represented by the formula [] HOOCR ₁ COOH (wherein R ₁ is the same as above). Specific examples of other copolymerizable vinyl monomers include the compounds exemplified as starting materials in production method (b). The acrylic resin used in producing the resin used in the present invention according to (a) above was prepared by appropriately copolymerizing the copolymerizable vinyl monomers exemplified in production method (b). It is preferable to use acrylic resin. The resin used in carrying out the present invention can be prepared by the methods (a), (b), (c), etc. described above. Although it is necessary that the resin contains 0.5 to 60% by weight of the group, it is preferable that the molecular weight of the polymer constituting these resins is 500 to 50,000. Electrophotographic materials for offset printing plates made from resins consisting of polymers with a molecular weight of 500 or less are unfavorable from a practical point of view because they have poor properties such as moisture resistance, adhesion, and printing durability; Electrophotographic materials for offset printing plates made using resins made of polymers with large polymers have good properties such as adhesion, but are undesirable because their charging properties tend to deteriorate significantly. Although the resin used in carrying out the present invention can sufficiently exhibit its characteristics even if it is composed of a homopolymer, in order to produce an electronic copying material for offset printing plates having particularly good characteristics, it is necessary to
Resin [A] made of a polymer containing 0.5 to 90% by weight of groups represented by formula [] and having an average molecular weight of 500 to 5000, and a proportion of 60% by weight or less of groups represented by formula [] The content of the group represented by the formula [] in the resin [B] is a polymer comprising a polymer with an average molecular weight of 5,000 to 50,000.
Electronic copying materials for offset printing plates made using resin compositions containing 0.5 to 60% by weight have good moisture resistance, particularly good image formation properties during copying, and produce clear printed matter. can be created. In particular, the glass transition temperature of the polymer constituting the resin [A] is in the range of -20 to +100°C, and the glass transition temperature of the polymer constituting the resin [B] is 0.
When a material having a glass transition temperature of -60 DEG C. is used, the image forming property of the electronic copying material for offset printing is excellent during image copying, and when printed using this material, good printed matter can be obtained. To make a fat composition consisting of the resin [A] and resin [B] described above, as shown in (a), a copolymer of an aromatic vinyl monomer and allyl alcohol or methallyl alcohol is mixed with the formula [] A method in which a resin [A] is prepared by modifying with an acid anhydride represented by the formula, and this resin [A] is mixed with the above-mentioned resin [B], and a vinyl monomer represented by the formula [] and other copolymerizable Copolymerize with a vinyl monomer, and when the glass transition temperature of the copolymer is -20 to +110℃, the group represented by the formula [] is 0.5 to
Resin [A] consisting of a polymer containing 90% by weight is polymerized by combining the vinyl monomer represented by the formula [] and other copolymerizable vinyl monomers if necessary, and the glass transition point of the copolymer is is 60°C or higher, and the resin [B] is made of a polymer containing 60% by weight or less of groups represented by the formula [], or in this method, the resin [A] and the resin [B] are mixed. In the production of the polymer, hydroxyalkyl (meth)acrylate was used instead of the vinyl monomer represented by the formula [] used as a starting material, and the hydroxyl group present in the polymer was replaced by the formula [] after the polymer production. A method for preparing a mixture of resin [A] and resin [B] by the same method except for modification with an acid anhydride, and a formula for copolymerizing resin [A] and resin [B] into a mixture. The glass transition temperature of the polymer obtained with 10 to 30% by weight of the total amount of vinyl monomers represented by [] and 70 to 90% by weight of the total amount of other copolymerizable vinyl monomers is 60°C or higher. A mixture of mainly monomers is charged into a polymerization pot,
When the polymerization rate reaches 50% or more, the entire remaining vinyl monomer is added to complete the polymerization to produce a mixture of resin [A] and resin [B], or as a starting material in the method. Polymerization is completed using a hydroxyalkyl (meth)acrylate in place of the vinyl monomer represented by the formula [] to be used, and then the hydroxyl groups contained in the resin composition are removed using an acid anhydride represented by the formula []. Methods such as denaturation can be used. In the resin used in the present invention, the total amount of (meth)acrylate structural units represented by the sum of formulas [] and [] is 10% by weight or more. The copying material has excellent image forming properties during copying and durability during printing, and provides clear printed matter. To make the electronic copy material for offset printing plates of the present invention, for example, 100 g of photoconductive powder (zinc oxide)
Add the resin of the present invention in a proportion of 10 to 50 g, add a sensitizer such as rose bengal or fluorescein as necessary, dilute it appropriately with a solvent, and place it on a high-strength paper that has been subjected to conductive treatment. The intermediate layer may be coated on top of the intermediate layer, and then dried. The electronic copying material for offset printing plates produced in this manner has excellent image forming properties during copying, good compatibility with desensitizing liquids, good durability during printing, and the ability to obtain clear printed matter. It can have extremely excellent properties. The present invention will be explained in more detail with reference to Examples below. Example 1 81 parts of a 50% toluene solution of hydroxyethyl methacrylate monophthalate, 112.5 parts of styrene,
Butyl methacrylate 44.8 parts, toluene 480 parts,
A mixture consisting of 1.8 parts of azobisisobutyronitrile was heated to 80°C to initiate polymerization. After starting polymerization 2
Add 3.0 parts of azobisisobutyronitrile at the 3rd hour and 3rd hour, and add 3.0 parts of azobisisobutyronitrile at
At 6.5 hours, 8.0 parts of azobisisobutyronitrile was added, and at 8.5 hours, 384 parts of toluene was added to complete the polymerization. The resulting polymer contains the formula

Contains about 3.2% by weight of the group [formula], and the solid concentration is
39.8%, and the average molecular weight of the polymer was about 12,000. 25 parts of resin obtained as above, rose bengal
0.02 parts, toluene 55 parts, photoconductive zinc oxide powder 60 parts
The two parts were mixed in a ball mill to obtain a photoconductive paint.
This paint is coated on a high-strength paper with conductive treatment on the back side and a partially cross-linked high molecular weight intermediate layer so that the film thickness after drying is 15 μm, and then dried. An electronic copying material for offset printing plates was created. The resulting copy material was left in a dark place at 20°C and 65% RH for 20 hours, and then its properties were measured dynamically using an electrostatic copying tester (Kawaguchi Electric Seisakusho MODEL, SP-428). As a result, -
When subjected to corona discharge treatment at 6KV for 5 seconds, the initial potential was -700V, and the surface static charge residual rate was 90% after 10 seconds in the dark.Then, when irradiated with 30 lux light, the potential of the photoconductive layer was -20V. The time required for the light to decrease (light attenuation rate) is 5.0 seconds, indicating that the electrostatic properties are extremely excellent. Further, when dry development was carried out using a commercially available copying machine, an extremely clear image with high image density, no fog, and excellent intermediate tones was obtained. And 30℃
Even when the samples were left in a 90% RH atmosphere for 20 hours and then developed, excellent images with high image density, clarity, and no fogging were obtained. Furthermore, the degree of fatigue during front exposure (500 lux for 60 seconds) was extremely low and no practical problems were observed. After applying a desensitizing process to the copied image, we printed it using a commercially available offset printing machine. Even after printing 5,000 sheets, there was no peeling of the photoconductive layer or wrinkles, and the image was clear. It was recognized that it was an excellent electronic copying material for offset printing plates, as it produced good printed matter. Example 2 A reaction vessel was charged with 100 parts of xylene and 5.5 parts of mercaptoethanol, and the temperature was raised to 120°C. 128 parts of butyl methacrylate, 24 parts of methyl methacrylate,
Add 8 parts of 2-hydroxyethyl methacrylate and 200 parts of xylene, and add t-butyl peracetate.
A mixture of 20 parts of 75% benzene solution and 200 parts of xylene was added dropwise over 5 hours, and after the addition was completed, the mixture was heated to 120℃ for 1 hour.
Polymerization was completed by holding for an hour. The resulting polymer has a glass transition temperature of approximately 35℃ and a molecular weight of 2900.
The hydroxyl value was 20. Mix 100 parts of the above polymer with 5.8 parts of phthalic anhydride, 105.4 parts of xylene, and 0.2 parts of triethylamine.
Addition reaction was carried out with stirring at ℃ for 5 hours.

A solution (a) of a polymer having an acid value of 10 containing 5.05% of the group [formula] was obtained. 20 parts of methyl methacrylate, 77.8 parts of butyl methacrylate, 1 part of acrylic acid, 2 parts of azobisisobutyronitrile, 0.2 parts of n-dodecyl mercaptan.
8 parts and 100 parts of toluene at 80°C.
After polymerization for a period of time, a resin solution (b) with a solid content concentration of 49.8% and an acid value of 3.7 was obtained. An electronic copying material for offset printing plates was prepared in the same manner as in Example 1, except that a composition consisting of 4 parts of resin solution (a) and 36 parts of resin solution (b) was used, and its properties were the same as in example 1. As a result of measurements, it showed excellent properties comparable to those of Example 1, and even after dry development, the image forming properties were good, and no peeling of the photoconductive layer was observed even after printing with this material. A clear printed matter was obtained. Example 3 An offset printing plate was prepared in exactly the same manner as in Example 2, except that the acid anhydrides shown in Table 1 were used in place of the phthalic anhydride used in the method for producing the polymer solution (a) prepared in Example 2. Table 1 shows the results of preparing electronic copying materials for use in offset printing plates and evaluating their properties, and all of them were found to be excellent electronic copying materials for use in offset printing plates.

[Table] Example 4 100 parts of a styrene-allyl alcohol copolymer (polyol RJ-100 manufactured by Monsanto) having a hydroxyl value of 18.2, an average molecular weight of 1600, and a glass transition temperature of 30°C.
47 parts of phthalic anhydride, 1.5 parts of triethylamine, and 37 parts of butyl acetate were mixed and subjected to an addition reaction at 100°C for 5 hours to form the formula

A resin solution (c) containing 31% of the group [formula] was obtained. 2 parts of resin solution (c) and the resin solution prepared in Example 2
(b) A photoconductive paint was prepared in the same manner as in Example 1 using the mixture with 38 parts, and the film thickness after drying was 20
An electronic copying material for an offset printing plate was prepared using the same method as in Example 1, except that the material was coated so as to have a thickness of . When offset printing was performed using this, more than 1000 good quality prints were obtained. Example 5 A mixture consisting of 2 parts of a 50% toluene solution of hydroxyethyl methacrylate monophthalate, 12 parts of methyl methacrylate, 72 parts of n-butyl methacrylate, 1015.5 parts of toluene, 7.5 parts of isopropanol, and 2 parts of azobisisobutyronitrile was heated at 80°C. When the polymerization rate reaches 90%, add 10 parts of a 50% toluene solution of hydroxyethyl methacrylate monophthalate, 1.5 parts of n-dodecyl mercaptan, and 1 part of azobisisobutyronitrile.
The mixture consisting of 20 parts of toluene was added dropwise to the above polymerization system over a period of 2 hours and 30 minutes, and polymerization was completed by further polymerizing at 80° C. for 4 hours, and a resin solution was prepared by adding 20 parts of toluene. Analysis of this resin solution revealed that it consists of two main resins, one with a molecular weight of approximately 15,000 and containing 1.2% phthalate groups, and the other with a molecular weight of approximately 4,000 and containing phthalate groups.
It contained 3.4%. Further, the phthalate group contained in this resin solution mixture was 6.8%, and the acid value was 4.0. The resin solution obtained as described above was mixed with photoconductive zinc oxide powder in the same manner as in Example 1, and then an electronic copying material for offset printing plates was prepared in the same manner as in Example 4, and wet developed. The images were clear with no fog, and moreover, when offset printing was performed, more than 1000 sheets could be printed.

Claims (1)

[Claims] 1 General formula -OOCR ₁ -COOH ......[] (In the formula, R ₁ is selected from the group [Formula] [Formula] [Formula] [Formula] [Formula] or [Formula] (R ₂ and R ₃ represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms) in an amount of 0.5 to 60% by weight, and a photoconductor. An electronic copying material for an offset printing plate, characterized in that it is provided with a photosensitive layer. 2 As resin [A] (In the formula, R ₄ represents a hydrogen atom or a methyl group, and R ₅ represents a group selected from a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group, and a benzyl group.) (In the formula, R ₁ and R ₄ have the same meanings as above, R ₆ is an alkyl group having 2 to 8 carbon atoms, a polyethylene glycol residue or a polypropylene residue having 10 or less repeating units, or -CH ₂ -CHCOH- (Indicates the group CH ₂ −.)
as well as (In the formula, X is a group selected from an aromatic group, a nitrile group, an amide group, or a substituted amide group, and R ₄ has the same meaning as above.) and is a group represented by the formula [] is 0.5 to 60% by weight, formula []
A patent claim characterized by using a resin in which the repeating unit represented by the formula [] is 90% by weight or less, and the sum of the repeating unit represented by the formula [] and the repeating unit represented by the formula [] is 10% by weight or more Electronic copying material for offset printing plates according to item 1. 3 As resin [A], for the hydroxyl group in the copolymer of aromatic vinyl monomer and (meth)allyl alcohol An acrylic resin is added to a resin containing a group represented by the formula [] obtained by addition reaction of a compound represented by the formula (wherein R ₁ has the same meaning as above), and a compound represented by the formula [] is obtained by adding an acrylic resin to a resin containing a group represented by the formula []. The group content is
2. The electronic copying material for offset printing plates according to claim 1, characterized in that the resin composition has a content of 0.5 to 60% by weight.