JPH04372671A - Emulsion ink for stencil printing - Google Patents

Abstract

PURPOSE:To impart a proper degree of viscosity to thereby prevent blotting, offset, etc., by incorporating a specified compound into the oil phase of the title ink comprising a dispersion of a coloring agent, an emulsifying agent, an aqueous phase, etc., in an oil phase. CONSTITUTION:A compound of formula I (wherein x is 8 to 18; y and z are each 0 to 6) is dissolved in an oil component (e.g. spindle oil) by heating, cooled and mixed with a coloring agent (e.g. cyanine blue) and an emulsifying agent (e.g. fatty acid monoglyceride). An aqueous phase is slowly added to the mixture to form an emulsion, thus producing the ink. It is suitable that the compound of formula I is added in an amount of 0.1-10 pts.wt. based on the total oil phase. This technique gives an ink which reveals a thickening effect suitable for thermal stencil printing even when an oil having a relatively low viscosity is used; therefore, the ink penetrates rapidly into printing paper so that a clear printed image can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emulsion ink for stencil printing, and more particularly to an emulsion ink for heat-sensitive stencil printing which has an appropriate viscosity and can produce a large number of high-quality printed matter.

0002

[Prior Art] As is well known, the stencil printing method uses a stencil printing base paper and moves ink from one side of the base paper to the other side through perforations formed by making a plate on the base paper. , to print on the surface of a printing target such as paper.

[0003] The perforations of this stencil printing base paper are, for example,
Typewriter base paper is formed by applying impact force, wax base paper is formed by applying frictional force with an iron pencil, or by using electrical energy such as discharge destruction. The perforations formed by such perforation methods have a relatively small opening area, and therefore, in order to achieve the necessary ink movement through the perforations,
As the mimeograph ink, it is necessary to use an ink that is relatively soft and fluid.

Incidentally, in recent years, stencil printing base paper in which plate making (perforation) is performed using flash exposure or thermal energy from a thermal head, etc., has become popular. The stencil printing base paper suitable for plate making using such a heat-sensitive method is different from the type of stencil printing base paper that is made using impact force, frictional force, or electrical energy, because the perforations in the stencil plate are large in diameter. When conventional soft mimeograph ink is used, too much ink passes through the perforations, resulting in so-called "protrusion" and "bleeding" phenomena, making it impossible to obtain clear printed images. There are drawbacks. Recently, mimeograph machines have been moving from two-cylinder types to single-cylinder types for the sake of simplicity and compactness of the mechanism. Due to its mechanism, a two-cylinder mimeograph machine does not supply more ink than necessary to the paper surface, so there is no problem with using soft ink.
In the case of single cylinder mimeograph machines, the use of soft ink causes problems such as ink leaking to the rear end of the master and staining the press rollers or the printed matter.

[0005] In order to eliminate these drawbacks, a method of thickening mimeograph ink using organic bentonite (Japanese Patent Publication No. 5
4-23601) has been proposed. Although this method is effective for mimeograph inks containing highly viscous oils such as #30 motor oil and #40 motor oil, it is effective for mimeograph inks containing low viscosity oils.
The drawback is that its thickening effect is not sufficient. Furthermore, since the mimeograph ink containing highly viscous oil has a slow rate of penetration into printing paper, it has the disadvantage of causing "set-off" during printing. Furthermore, when a pigment-based thickener is used, there is a problem that the fibers of the stencil printing base paper become clogged, and the density decreases as the number of printed sheets increases.

[0006]

[Problems to be Solved by the Invention] An object of the present invention is to prevent ink from ``protrusion'' and ``bleeding'' by maintaining appropriate hardness in the ink flowing out from the perforations formed in the stencil printing base paper. To provide an emulsion ink for stencil printing which gives a clear printed image without causing "set-off". Another object of the present invention is to provide an emulsion ink for heat-sensitive stencil printing, which is suitable for use not only in a two-cylinder stencil printer, but also in a single-cylinder stencil printer.

[0007]

[Means for Solving the Problems] The present invention provides an emulsion ink for stencil printing in which at least a colorant, an emulsifier, and an aqueous phase are dispersed in an oil phase, further comprising a compound represented by the following general formula in the oil phase. It is characterized by containing. (In the formula, x is an integer of 8 to 18, preferably 10 to 16, y
and z is an integer of 0 to 6, preferably 1 to 5. )

0
The compound represented by the above general formula is commonly called an oil gelling agent, and when dissolved in oil,
Carbonyl groups and imino groups in the molecule form hydrogen bonds to form a three-dimensional network structure, and oil is incorporated into this structure to thicken or gel. That is, in the case of the present invention, even if a relatively low-viscosity oil with good permeability is used, by adding an appropriate amount of the compound represented by the above general formula, a thickening effect suitable for thermal stencil printing can be exerted. be able to. In addition, the compound according to the present invention has a very large thickening effect, so
It is effective even when added in a small amount, and does not cause clogging of the fibers of the stencil printing base paper.

[0009] Here, specific examples of the compound represented by the above general formula are as follows. These may be used alone or in combination of two or more.

The emulsion ink for stencil printing of the present invention is a water-in-oil emulsion consisting of about 10 to 50% by weight of an oil phase and about 90 to 50% by weight of an aqueous phase, and a compound represented by the above general formula is added to this oil phase. 0.0% based on the total amount of the oil phase.
The content is 1 to 10% by weight, preferably 0.5 to 5% by weight. If it is less than 0.1% by weight, the thickening effect will be weak;
If the content exceeds this weight percent, the perforations will become clogged.

[0011] As the oil component in the oil phase used in the present invention, conventionally known ones can be used, such as liquid paraffin, spindle oil, light oil, kerosene, machine oil, mineral oil for lubricating oil; olive oil, rapeseed oil. , vegetable oils such as castor oil and soybean oil are used.

[0012] Synthetic oils can also be used in the present invention. When using synthetic oils, a variety of compounds are available. Typical synthesis vehicles are polyisobutylene, polyisobutenes, hydrogenated polydecenes, trimethylolpropane esters, neopentyl esters and pentaerythritol esters, di(2-ethylhexyl) sebacate, di(2-ethylhexyl) adipate, dibutyl phthalate. , fluorocarbons, silicic acid esters, silanes, phosphorus-containing acid esters, liquid urea, ferrocene derivatives, hydrogenated synthetic oils, chain polyphenyls,
Siloxanes and silicones (polysiloxanes),
Examples include alkyl-substituted diphenyl ethers represented by butyl-substituted bis(p-phenoxyphenyl) ethers, phenoxyphenyl ethers, and the like.

The emulsifier used in the present invention is preferably a nonionic surfactant, such as sorbitan higher fatty acid ester, polyoxyethylene sorbitan higher fatty acid ester, fatty acid monoglyceride, fatty acid diglyceride, higher alcohol, alkylphenol, fatty acid, etc. Examples include ethylene oxide adducts, etc., and highly stable emulsions can be prepared by using these alone or in combination of two or more of these with different HLBs.

[0014] Examples of the coloring agent used in the present invention include organic and/or inorganic pigments such as furnace carbon black, lamp black, cyanine blue, cyanine green, lake red, titanium oxide, and calcium carbonate. .

An appropriate amount of resin is added to the oil phase for the purpose of improving the stability of the emulsion ink over time and improving the adhesion of the ink to paper. Examples of such resins include alkyd resins, rosin-modified alkyd resins, polymerized castor oil, rosin, polymerized rosin, hydrogenated rosin, rosin esters, hydrogenated rosin esters,
Terpene resin, petroleum resin, rosin modified phenolic resin,
Examples include maleic acid resin and rubber derivative resin.

On the other hand, in addition to water, conventionally known water-soluble resins, electrolytes, antifungal agents, antifreeze agents, antioxidants, etc. can also be used in the aqueous phase.

The emulsion ink of the present invention is prepared by heating and dissolving the oil component in the oil phase and the compound represented by the general formula of the present invention, followed by cooling. When adding resin, heat and dissolve it together. It can be produced by adding and mixing a colorant and an emulsifier, and then gradually adding an aqueous phase to emulsify. The mixing order of these components is not limited to the above, and can be changed as appropriate.

[0018]

EXAMPLES The present invention will be explained in more detail by way of examples. Parts here are by weight.

Examples 1 to 3 and Comparative Example 1 Super oil (motor oil manufactured by Nippon Oil Co., Ltd.) shown in Table 1 below
and Solvent No. 6 (manufactured by Nippon Oil Co., Ltd.) were heated to 120° C., and the compound represented by the above general formula and rosin-modified glycerin ester were added and dissolved therein. After cooling to 30℃,
Carbon black and sorbitan monooleate were added and dispersed using a three-roll mill. Water was added to this dispersion to emulsify it, and then passed through a three-roll mill to obtain an emulsion ink for stencil printing. In addition, in Comparative Example 1, the amount of carbon black was increased in order to maintain the same viscosity (flow value) of the ink instead of adding the compound represented by the above general formula.

[0020] Using these four types of inks, printing was carried out using a heat-sensitive stencil printing machine (Priport SS955 manufactured by Ricoh Co., Ltd.),
The print density and flow value were measured, and the set-off condition was observed. Print density was measured with a Macbeth densitometer RD-914. Set-off was determined visually. The flow value was determined by measuring the diameter 1 minute after the start of measurement using a spread meter. The results are summarized in Table 1.

[Table 1] (*1) N-lauroyl-L-glutamic acid-α,
γ-di-n-butyramide (*2) N-stearoyl-L-glutamic acid-α, γ-di-n-butyramide

[0021]

Effects of the Invention By adding a small amount of a specific compound (compound represented by the above general formula) to the emulsion ink for stencil printing of the present invention, even when using relatively low viscosity oil, heat-sensitive stencil printing is possible. Since it exhibits a thickening effect suitable for printing, it penetrates into printing paper quickly and does not cause "set-off" or clogging of the fibers of stencil printing base paper. In addition, the three-dimensional network structure allows the ink to maintain an appropriate level of hardness, allowing an appropriate amount of ink to flow out from the perforations in the thermal stencil printing base paper, preventing ink from ``extruding'' or ``bleeding''. A clear printed image can be obtained without causing "."

Claims (2)

[Claims] [Claim 1] An emulsion ink for stencil printing in which at least a colorant, an emulsifier, and an aqueous phase are dispersed in an oil phase, characterized in that the oil phase contains a compound represented by the following general formula. Emulsion ink for stencil printing. CH3(CH2)x CONHCHCONH(CH2)
yCH3
｜CH2CH2CONH(CH2)z C
H3 (where x is an integer of 8 to 18, and y and z are integers of 0 to 6.) 2. Claim 1, wherein the proportion of the compound represented by the general formula in the entire oil phase is 0.1 to 10 parts by weight.
Emulsion ink for stencil printing as described.