JPH0420183B2 - - Google Patents

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a correction fluid for copied images.
This invention relates to a copy image correction liquid suitable for manually stamping toner images mainly created by electrophotography (offset master toner images, toner images of second originals for PPC) and dye images of second originals for diazo copying. Prior Art Currently, planographic printing original plates include () an electrophotographic printing original plate having a photosensitive layer in which inorganic photoconductive particles such as zinc oxide particles are dispersed in a binder resin, and () a water-resistant treated original plate. An image-receiving layer in which an inorganic pigment such as titanium oxide is dispersed in a binder resin is provided on paper, etc., and an image can be formed by writing or typing directly on this layer with oil-based ink. Original direct plate, ()
Presensitization is a method in which a photosensitive layer of photocurable resin is provided on a grained aluminum plate, and a lipophilic image is formed by utilizing the difference in solubility between exposed and unexposed areas of the photosensitive layer. Plate (PS version) etc. are known and put into practical use. Furthermore, recently, it has become possible to form an oil-based toner image on the above-mentioned direct plate original plate using electrophotography using a plain paper copying machine (PPC machine), and use this as a lithographic printing plate (offset master). , has become widely used due to the ease of plate making. The original plate (plate material) suitable for such plate making is, for example, the PPC type manufactured by Ricoh Co., Ltd.
It is commercially available as MA Master. Note that the offset master is used for printing after the non-image area is treated with a desensitizing liquid (etching liquid). Incidentally, the reality is that toner images formed using a PPC machine are often modified. Correction of toner images is also often performed in correction of second original images for PPC. Toluene, butyl acetate, carbon tetrachloride, etc., which have been conventionally considered to be excellent toner image correction liquids, can also be used as correction liquids, assuming toxicity and flammability are not considered. However, these generally commercially available toner image correction liquids (solvents) cannot be used for correction of offset masters. The first reason is that the solubility of these solvents is so strong that they also dissolve the hydrophilic resin that makes up the non-image area. The second reason is that these solvents dissolve all the resins forming the toner image, that is, the resin components constituting the toner, become fine particles or liquid, and spread to non-image areas as stains. Incidentally, examples of the hydrophilic resin (binder resin) include casein, oxidized starch, polyvinyl alcohol, carboxymethyl cellulose metal salt, alginate metal salt, etc., and examples of the resin component of the toner include: Examples include styrene resin, acrylic resin, polyester resin, epoxy resin, phenolic resin, and fluororesin. On the other hand, the need for image correction also exists in the second diazo original. As for the diazo second original drawings that have been commercially available, there are many types of paper made by Ricoh Co., Ltd., depending on the model of the diazo copier, such as SD-45, IZE, PF, SD-40,
There are 40L etc. Among these, SD-45, IZE, and PF are resin paper coated with a composition containing a diazo compound, and therefore the diazo image must be removed with an organic solvent. SD-40 and 40L are plain paper impregnated with a composition containing a diazo compound, so the diazo image penetrates deep into the paper.Therefore, these two types are generally treated with organic solvents, etc. Since it cannot be removed by dissolution, chemical reduction and decomposition methods are used. However, the above-mentioned problem that can be corrected with organic solvent type
Although dedicated correction fluids are commercially available for SD-45, IZE, and PF, almost all of these correction fluids use solvents regulated by the Ordinance on Prevention of Organic Solvent Poisoning, and there are safety concerns. Improvements were also desired from above. OBJECTIVE: The present invention provides a copy image correction liquid which eliminates the above-mentioned disadvantages and is suitable for obtaining high-quality offset masters, second original drawings, etc. Composition The copy image correction liquid of the present invention is characterized by containing alkyl acetoacetate and diethylene glycol dimethyl ether and/or diethylene glycol diethyl ether as main components. In order to achieve the above object, the present inventors conducted tests by selecting and combining many organic solvents, and found that methyl lactate, ethyl lactate, methyl acetoacetate, and ethyl acetoacetate and polyhydric alcohol Among derivatives such as ethylene glycol dimethyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, etc., especially It was confirmed that the combination of alkyl acetoacetate (methyl acetoacetate or ethyl acetoacetate) and diethylene glycol dimethyl ether or diethylene glycol diethyl ether had excellent correction performance for toner images and diazo images, and the present invention was thereby completed. This is what I did. The blending ratio of alkyl acetoacetate and diethylene glycol dimethyl ether and/or diethylene glycol diethyl ether is 70:3 to 98:
2 (volume %) preferably 80:20 to 95:5 (volume %)
Excellent correction performance can be obtained within the range of . Methyl acetoacetate or ethyl acetoacetate alone has a low ability to dissolve toner images, which tends to take too much time for correction work, while diethylene glycol dimethyl ether or diethylene glycol diethyl ether alone has too strong a dissolving power and can cause toner images to disappear. It tends to dissolve the coating on the parts. Since the correction fluid of the present invention has appropriate resin solubility, it does not cause fine dispersion and destruction of toner images. Therefore, even toner images formed on impregnated translucent paper, which is relatively similar to plain paper among the several types of translucent paper commercially available for use as PPC second originals, can be corrected. Furthermore, as can be seen from the examples below, the correction fluid of the present invention is also effective in correcting diazo images. Next, examples will be shown. Example 1 Alkyl acetoacetate and diethylene glycol dialkyl ether were blended as shown in Table 1,
This liquid (correction liquid) was used to correct the toner image area on a "Type MA Offset Master" manufactured by Ricoh Co., Ltd. using a cotton swab.

[Table] The performance of the modification is shown in Table-2. The performance after offset printing was examined by printing 500 sheets using an offset printing machine (AP-1600, manufactured by Ricoh Co., Ltd.).

[Table] represents.
Example 2 PPC second original drawing type TA manufactured by Ricoh Co., Ltd.
Toner images were formed on TB, TC, TD, TE, FA, and P-500, and the performance of the correction liquid according to the present invention was investigated by comparing it with commercially available correction liquids. The correction method was the same as in Example 1. The results are shown in Table 3.
According to the product of the present invention, it is now possible to successfully correct TC, TE, and P-500 type toner images, which have been difficult to correct.

[Table]
Example 3 Diazo second original drawing SD-45 manufactured by Ricoh Co., Ltd.
The diazo images on IZE and PF were corrected using a commercially available correction liquid and a correction liquid of the present invention. The correction method was to rub the repaired area with a cotton swab moistened with correction fluid, then wipe it off with a piece of tissue paper. The results were as shown in Table 4.

[Table] represents.
Effects As described above, the correction fluid of the present invention has excellent performance in correcting a wide range of copied images.

Claims (1)

[Claims] 1. Copy image correction liquid containing alkyl acetoacetate and diethylene glycol dimethyl ether and/or diethylene glycol diethyl ether as main components.