JP2880682B2 - Emulsion ink for stencil printing - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil printing emulsion ink, and more particularly to an ink for stencil printing, which prevents an increase in print density after standing, paper soaring, and ink set-off. The present invention relates to a stencil printing emulsion ink suitably used for a rotary stencil printing machine, particularly a single cylinder stencil printing machine. 2. Description of the Related Art In recent years, rotary stencil printing presses have been automated by microcomputers and the like, and the operation thereof has been simplified, and accordingly, it has been demanded that a good printed matter can be obtained immediately after the start of printing. I have. However, unlike conventional rotary stencil printing presses, unlike offset printing presses, it is difficult to dry the ink so that it does not have to be cleaned every day. However, in printing after leaving for one or two or three days, the printing density is higher than the normal printing density, and the printing paper sticks to the plate cylinder, causing the paper to flutter or clog, and However, there is a drawback that the set-off is increased, and a considerable number of sheets (especially sometimes more than 1000 sheets in a single cylinder type stencil printing machine) are required to obtain good printed matter.
Has to be imprinted. [0003] Conventional emulsion inks for stencil printing include high-boiling solvents such as non-drying oils and non-volatile mineral oils (motors) in order to prevent clogging due to drying on the plate cylinder of the stencil printing machine during standing. Oil, liquid paraffin, spindle oil, machine oil, castor oil, etc.) (Japanese Patent Publication No. 44-2165). When this emulsion ink is left in a stencil printing machine, only the water in the emulsion evaporates, so that the balance between water and oil is lost and the proportion of oil increases. As a result, the proportion of water relatively decreases, the viscosity of the emulsion ink decreases, and the ink softens. As a result of the softening of the ink as described above, at the start of printing after leaving the ink, the ink flows out of the plate cylinder and a large amount of ink adheres to the paper, and the printing density becomes higher than the normal printing density as described above. In addition, the printing paper sticks to the plate cylinder, causing the paper to soar or jam, and the ink transferred to the paper overlaps with the next paper before the ink dries, so the ink adheres to the back side of the paper and the ink is set off. Occurs. SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above, and to increase the print density of a rotary stencil printing machine when printing is restarted after leaving the ink unattended. An object of the present invention is to provide a stencil printing emulsion ink which does not cause offset or ink set-off. The present inventors have conducted various studies to solve the above-mentioned problems. As a result, the present inventors have found that the oil phase of a water-in-oil emulsion ink together with a high-boiling solvent and a non-boiling medium having a high boiling point are contained. By containing the water-soluble solvent in an amount of 5% by weight or more based on the total amount of the aqueous phase of the emulsion, the solvent in the oil evaporates slightly with the evaporation of the water in the emulsion, and the change in the ratio of water to oil is kept small. Thus, the present invention was found to be able to prevent a decrease in the viscosity of the ink and prevent the ink from softening. According to the present invention, an oil phase of 10 to 50% by weight and an aqueous phase of 9 % are used.
In a water-in-oil type emulsion ink comprising 0 to 50% by weight, the oil phase has a boiling point of 180 to 267 ° C of 5% by weight or more based on the total amount of the high boiling solvent and the aqueous phase.
The present invention relates to a stencil printing emulsion ink containing a medium-boiling water-insoluble solvent. The emulsion ink for stencil printing of the present invention comprises a water-in-oil emulsion composed of 10 to 50% by weight of an oil phase and 90 to 50% by weight of an aqueous phase. oil consisting of medium boiler Tenhi water-soluble solvent, emulsifiers, coloring agents, consists of a resin or the like, also the aqueous phase water,
It is composed of a water-soluble resin, electrolyte, fungicide, water evaporation inhibitor, antioxidant and the like. Known components that do not inhibit the formation of an emulsion are used as these components. Among these components, components other than water, oil and emulsifier are optional components, and can be appropriately added. [0008] In the present invention, the medium boiling water-insoluble solvent refers to a water-insoluble solvent having a boiling point in the range of 180 to 267 ° C. If the boiling point of the water-insoluble solvent is lower than 180 ° C., if the stencil printing machine is left for a long time without printing, the ink dries on the plate cylinder and causes clogging. On the other hand, if the boiling point exceeds 267 ° C., it does not differ from that of the conventional oil phase component, and it is not possible to prevent a decrease in viscosity after standing. The medium-boiling water-insoluble solvent may be any as long as it dissolves the resin to be added to the ink at a boiling point in the range of 180 to 267 ° C., for example, a petroleum-based solvent, specifically Means ink solvent 240 (boiling point 2
42-260 ° C, manufactured by Mitsubishi Petroleum Corporation), Nisseki Isosol 4
00 (boiling point: 206-257 ° C., manufactured by Nippon Oil Co., Ltd.), shell dispersol (boiling point: 205-252 ° C., manufactured by Shell Chemical Co., Ltd.), Nisseki No. 4 solvent (boiling point: 238-267 ° C., manufactured by Nippon Oil Co., Ltd.), etc. Can be In the present invention, the water-insoluble solvent having a medium boiling point is 5% by weight or more, preferably 10% by weight, based on the total amount of the aqueous phase.
It must be contained in an amount of at least% by weight. This allows the oil solvent to evaporate slightly as the water in the emulsion evaporates, so that the amount of change in the water-to-oil ratio can be reduced, thereby preventing the viscosity of the ink from lowering and providing rotary stencil printing. It is possible to prevent the ink from softening on the press. The high boiling solvent used in the present invention includes:
A solvent having a higher boiling point than the medium boiling non-water-soluble solvent,
For example, olive oil, castor oil, salad oil, sardine oil,
Non-drying oils and nonvolatile mineral oils generally used for oil-based stencil inks, such as whale oil, machine oil and spindle oil, are used.
In the present invention, there is no particular limitation on the mixing ratio of the high-boiling solvent and the medium-boiling water-insoluble solvent in the oil phase. A resin is added to the emulsion ink of the present invention for the purpose of improving the storage stability of the ink, improving the fixability of the ink to paper, and improving the finish of printed matter. Examples of these resins include a phenol resin, a maleic resin, a petroleum resin, an alkyd resin, a rubber derivative resin, and the like. Examples of the water-soluble resin include carboxymethyl cellulose, methyl cellulose, gum arabic and the like. These resins also have a water evaporation preventing effect. As the emulsifier used for forming the water-in-oil emulsion, a nonionic surfactant is preferably used, and sorbitan higher fatty acid esters (eg, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monopalmate) Stearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate, etc.)
Fatty acid monoglycerides such as oleic acid monoglyceride, oleic acid diglyceride, and higher alcohols;
Ethylene oxide adducts such as alkyl phenols and fatty acids; and those having low and high HLB of 2
By combining more than one kind and adjusting HLB, an emulsion having high stability can be obtained. As the evaporation inhibitor, polyhydric alcohols such as ethylene glycol, propylene glycol, sorbitol and glycerin, and polyethylene glycol are used. Known coloring agents such as furnace carbon black, lamp black, and brilliant fast scarlet are used as the coloring agent. As the electrolyte, for example, sodium sulfate, sodium hydrogen phosphate, sodium borate and the like are used. Examples of the fungicide include phenols, methyl p-oxybenzoate,
Ethyl p-oxybenzoate and the like, sorbic acid, dehydroacetic acid, salicylic acid and the like are used. As an antioxidant such as resin, for example, dibutylhydroxytoluene, propyl gallate, butylhydroxyanisole and the like are used. The stencil printing emulsion ink of the present invention is prepared, for example, by heating and dissolving the oil component and the resin, adding a colorant and an emulsifier thereto and mixing them, and then gradually adding an aqueous solution of an electrolyte to emulsify the resin. It can be manufactured by doing. The order of mixing these components is not limited to the above, and can be changed as appropriate. Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. Parts in the examples mean parts by weight. Example 1 Furnace carbon black 3 parts Ink solvent 240 (boiling point 242 to 260 ° C) 7 parts Spindle oil (boiling point 270 to 378 ° C) 7 parts Rosin-modified phenolic resin 9.8 parts Sorbitan sesquioleate 5 parts dibutylhydroxytoluene 0. 1 part Water 65 parts Sodium sulfate 3 parts Methyl parahydroxybenzoate 0.1 part The ink solvent 240 and the rosin-modified phenol resin are heated and dissolved at the above ratio (170 ° C.), and dibutylhydroxytoluene is added. After mixing carbon black and sorbitan sesquioleate and kneading them sufficiently with three rolls, the mixture is emulsified by stirring with a stirrer while gradually adding an aqueous phase consisting of an aqueous sodium sulfate solution containing methyl paraoxybenzoate,
An emulsion ink of the present invention was obtained. This emulsion ink is used in a single cylinder rotary stencil printing press RISOGRAPH AP7200.
(Manufactured by Riso Kagaku Kogyo Co., Ltd.), printing was performed sufficiently, and the ink was spread in the printing machine. After being left for 48 hours, printing was resumed. At this time, the print density of the printed matter was measured by a reflection optical densitometer (DM-400 manufactured by Dainippon Screen Co., Ltd.), and the results are shown in FIG. The horizontal axis in FIG. 1 shows the number of printed sheets after standing, and the vertical axis shows the optical density.
Note that the print density in the normal state is 0.7. Example 2 Furnace carbon black 3 parts Ink solvent 240 5.6 parts Spindle oil 8.4 parts Rosin-modified phenolic resin 9.8 parts Sorbitan sesquioleate 5 parts Dibutylhydroxytoluene 0.1 parts Water 65 parts Sodium sulfate 3 parts of methyl paraoxybenzoate 0.1 part The above compound was emulsified in the same manner as in Example 1 except for using the above compound to obtain an emulsion ink of the present invention. This was placed in a lithographic AP7200 and printed after standing in the same manner as in Example 1. The result is shown in FIG. Example 3 Furnace carbon black 3 parts Ink solvent 240 4.2 parts Spindle oil 9.8 parts Rosin-modified phenolic resin 9.8 parts Sorbitan sesquioleate 5 parts Dibutylhydroxytoluene 0.1 parts Water 65 parts Sodium sulfate 3 parts of methyl paraoxybenzoate 0.1 part The above compound was emulsified in the same manner as in Example 1 except for using the above compound to obtain an emulsion ink of the present invention. This was placed in a lithographic AP7200 and printed after standing in the same manner as in Example 1. The results are shown in FIG. Comparative Example 1 Furnace carbon black 3 parts Spindle oil 12 parts Rosin-modified phenolic resin 9.8 parts Sorbitan sesquioleate 5 parts Dibutylhydroxytoluene 0.1 parts Water 67 parts Sodium sulfate 3 parts Methyl paraoxybenzoate 0.1 Part of the above compound was emulsified in the same manner as in Example 1 to obtain an emulsion ink of Comparative Example 1. This was placed in a lithographic AP7200 and printed after standing in the same manner as in Example 1. The results are shown in FIG. Comparative Example 2 Furnace carbon black 3 parts Ink solvent 240 2.8 parts Spindle oil 11.2 parts Rosin-modified phenolic resin 9.8 parts Sorbitan sesquioleate 5 parts Dibutylhydroxytoluene 0.1 parts Water 65 parts Sodium sulfate 3 parts of methyl paraoxybenzoate 0.1 part The above compound was used, and the others were emulsified in the same manner as in Example 1 to obtain an emulsion ink. This is lithograph A
P7200, and after standing, printing was performed in the same manner as in Example 1. The results are shown in FIG. As is clear from the results shown in FIG.
In the case of the emulsion ink using only the non-volatile mineral oil, the initial print density after standing is 0.35 higher than the density of the normal printed matter, and more than 1600 sheets until the print density in the normal state is reached. While you need to print,
In the case of the emulsion ink of the present invention, the density of the printed matter at the beginning is only 0.14 to 0.18 higher than the normal state, and the density of the printed matter is almost the same as that before leaving for 100 to 400 sheets. Return to concentration. In addition, in the case of the present invention, the paper did not rise or jam, and the degree of set-off was not different from that during normal printing. Also, as is apparent from the results in FIG. 1, in the case of Comparative Example 2 in which a water-insoluble solvent having a boiling point of 180 to 267 ° C. was contained in the oil phase at a ratio of less than 5% by weight based on the total amount of the aqueous phase. Compared with the case where the emulsion ink of the present invention is used, the initial print density after standing is high, and the number of prints until the print density in the normal state is considerably increased. According to the emulsion ink for stencil printing of the present invention, the viscosity of the ink does not decrease even after standing for a few days.
Therefore, when the rotary stencil printing is performed using the ink of the present invention, even at the start of printing after being left, an increase in print density due to excessive outflow of ink, flying of paper, jamming,
It is possible to quickly shift to the normal operation state without causing ink set-off or the like. Moreover, the emulsion ink of the present invention does not dry in a stencil printing machine even after being left for about 40 days, even though it contains a water-insoluble solvent having a lower boiling point than the conventional emulsion ink in the oil phase. It turned out to be practical. Further, when the emulsion ink for stencil printing of the present invention is used, set-off during normal printing is reduced as compared with the case where a conventional emulsion ink is used. Therefore, when the emulsion ink for stencil printing of the present invention is used in a rotary stencil printing machine, in particular, a single-cylinder stencil printing machine, a normal printing state can be obtained in a short time with a significantly reduced number of test prints even at the start of printing after standing. And a better printed matter than before can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a drawing showing the measurement results of print density when printing is started after leaving the emulsion ink of the present invention for 48 hours.

Claims (1)

(57) [Claims] In a water-in-oil emulsion ink composed of 10 to 50% by weight of an oil phase and 90 to 50% by weight of an aqueous phase, 5% by weight or more of the high boiling solvent and the total amount of the aqueous phase in the oil phase.
An emulsion ink for stencil printing , comprising a medium-boiling water-insoluble solvent having a boiling point of 180 to 267 ° C.