JPH08176484A - Stamp ink for stencil printing - Google Patents

Abstract

PURPOSE: To obtain a stamp ink which is persistently stable at a viscosity suitable for stamping and increased in the speed of infiltration into paper by bringing it closer to a Newtonian fluid and which, as the result, has good fixability and sets quickly. CONSTITUTION: This ink consists of, based on the total ink composition, 30-97wt.% oil-modified alkyd resin obtained by the condensation of an aromatic polycarboxylic acid, a polyhydric alcohol and an oil or fat and having an oil length of 60 to 90, 2-40wt.% palm oil or fractionated palm oil, 0-40wt.% of other solvent, and 1-30wt.% coloring agent component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink for a stamper using a stencil printing method.

[0002]

2. Description of the Related Art Stencil printing is a method in which after plate making, ink is transferred from the perforated portion of a stencil sheet and transferred to the paper to form an image. The stencil printing ink includes an oil-based ink type composed of a pigment, a resin and a solvent (for example, Japanese Patent Publication No. 33-6516) and an emulsion type in which water, an activator and the like are further added. In both types, if the ink dries, the perforated part of the stencil paper will be clogged and the ink will not come out, so for mineral oil and vegetable oil with a high boiling point, non-drying oil such as cottonseed oil and castor oil, semi-drying oil is used. To prevent drying.

On the other hand, stamp inks are composed of pigments or dyes, resins, solvents, activators, etc., and include water-based inks and oil-based inks. Make sure that the ink used for the stamping device that seals the ink with the lid always closed (mainly the simple type in which the ink-impregnated stamp and the printing surface are integrated) has good dryness after imprinting Volatile alcohol solvents and low molecular weight aromatic solvents are used. In addition, without using a lid, use a glycol-based solvent for the ink used in the stamper that uses the ink in an open system (a type that uses the stamp and the printing plate separately) so that the surface of the stamp does not dry. However, most of them balance the evaporation and absorption of water.

However, even if the above ink is used for a stencil printing type stamp ink, a good printed matter cannot be obtained. That is, the oil-based ink for stencil printing thickens with time, and in the worst case, oil separation (pigment precipitation) occurs. Emulsion inks for stencil printing have strong thixotropy or plasticity, the ink does not come out easily from the beginning, and the penetration into paper is slow, so the fixability is poor and the setting (drying of the paper surface) is slow. On the other hand, if the water evaporates over time and the viscosity decreases, too much ink will come out, causing bleeding on the printed matter and slow drying. The stamp ink of a system using a volatile solvent is instantly dried and the stencil sheet is clogged. Stamp inks of a system using a non-volatile solvent increase in viscosity over time, and in severe cases, oil is separated.

[0005]

Compared with the conventional stencil ink and stamp ink, the performance required for the stencil printing type stamp ink is to improve the viscosity stability and fixing property over time and to set it. The time (time until the paper surface is dried) is shortened. If the ink viscosity is too high or the thixotropic property or the plasticity is too strong, the ink does not come out well, and the printed image becomes faint or thin. In addition, the permeation of ink into the paper is delayed (setting is slow), and the paper is rubbed to stain the paper or the hands. If the viscosity of the ink is too low, too much ink will be ejected, the printed image will bleed, the drying of the printing surface will be delayed, and the surface will be rubbed and soiled, or the hands will be soiled. When the ink separates from the oil, the oil oozes out onto the paper and stains the printed matter, and the pigment that has settled out clogs the stencil sheet. In addition, if the fixability of the ink is inferior, the surface of the paper will be rubbed and the surface of the paper will be soiled or the hands will be soiled. The present invention provides a stamp ink that has a viscosity suitable for printing and is stable for a long period of time, and that when it approaches a Newtonian fluid, it penetrates quickly into paper, resulting in good fixing properties and quick setting. It is an object.

[0006]

That is, according to the present invention, 30 weight parts of an oil-modified alkyd resin having an oil length of 60 to 90 obtained by condensing an aromatic polyhydric carboxylic acid, a polyhydric alcohol and a fat and oil is contained in the entire ink composition. % To 97% by weight, palm oil or a fractionated fraction of palm oil from 2% to 40% by weight, solvents other than the above from 0% to 40% by weight, and colorant components from 1% to 30% by weight. It is a stamp ink for stencil printing, characterized in that

As shown in FIG. 1, the stamper according to the present invention has a stencil printing method as shown in FIG. The stencil sheet is attached to the printing surface, and when you hold the container by hand and press it against the paper,
The ink bleeds from the perforated portion of the stencil sheet and is printed.

The alkyd resin of the present invention comprises oils and fats, polybasic acids and polyhydric alcohols as constituents. As the oil and fat, non-drying oil or semi-drying oil such as palm oil, palm oil, olive oil, castor oil and cottonseed oil is preferable. The oil length of the alkyd resin is from 60 to 90, more preferably from 70 to 80, and the storage stability of the ink decreases if the oil length is shorter or longer than the above value. If it is too short, the fixing property of the ink is further deteriorated and the setting becomes slow.

In the present invention, it is preferable to use terephthalic acid as the polybasic acid in terms of storage stability, fixability and setting of the ink, but isophthalic acid, phthalic anhydride, trimellitic anhydride, tetrahydrophthalic acid are used. It may be. However, succinic acid, adipic acid, sebacic acid and the like can be used together within a range that does not impair the effects of the present invention, that is, within a range of 30% by weight or less of the total amount of polybasic acid.

In the present invention, it is preferable to use pentaerythritol as the polyhydric alcohol in terms of storage stability, fixing property and setting of the ink, but ethylene glycol,
Diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, glycerin, trimethylolpropane, trimethylolethane,
It may be neopentyl glycol, diglycerin, triglycerin, dipentaerythritol, mannite or sorbit. In the present invention, other alkyd resins, rosin esters, rosin-modified phenolic resins, petroleum resins, gilsonite and other resins can be used in combination as the resin.

The effect of the palm oil or the fractionated distillation product of palm oil in the present invention is exhibited by adding 2% by weight to 40% by weight, preferably 5% by weight to 20% by weight. Conventionally, palm oil or fractionated distillates of palm oil have not been used in stencil inks. This is because other vegetable oils have a freezing point of 30 to 50 ° C. and are not suitable as a solvent, as compared with liquids at room temperature. However, the alkyd resin of the present invention is liquid at room temperature, and palm oil or a fractional distillation product of palm oil added thereto and heated and melted in advance has good compatibility, so that crystals are formed at 0 to 30 ° C. Does not precipitate. Fractional distillation of palm oil has a freezing point of 10 ° C.
Although it is about -15 ° C, crystals do not precipitate at around 0 ° C. Therefore, it can be used as a solvent or an additive.

[0012] The solvent is suitably 0 to 40% by weight other than palm oil or a fractional distillation product of palm oil, and one having extremely low volatility is preferable. This is because if it is volatile, the viscosity will increase over time. For example, a synthesis obtained by polymerization of a hydrocarbon solvent having a boiling point of 300 ° C. or higher, a petroleum solvent such as spindle oil, liquid paraffin, motor oil, gear oil, machine oil and the like, and unsaturated hydrocarbon such as ethylene, propylene, butene and the like. The oil is raised. Animal or vegetable oils such as castor oil, tall oil, soybean oil, olive oil, whale oil can also be used.

As the colorant contained in the ink of the present invention, it is possible to use an inorganic pigment such as carbon black, titanium dioxide or dark blue, an organic pigment such as a phthalocyanine pigment, an insoluble azo pigment, a soluble azo pigment or a quinacridone pigment. it can. A pigment concentration of 1 to 30% by weight is suitable. If the amount is too small, the color at the time of printing becomes light, and if the amount is too large, the penetration of the pigment into the paper is slow, and the paper is rubbed and the hands are soiled (the fixing property is poor and the setting is slow).

If desired, various additives may be used within a range that does not impair the effects of the present invention. Examples thereof include extender pigments, extenders, pigment dispersants, abrasion resistance improvers, antioxidants, anti-setoff agents, and thixotropic agents. The thixotropic agent can be added in the ink or at the time of resin preparation. The stamp ink for stencil printing of the present invention,
Add a colorant to all or part of the resin or solvent, knead and disperse with a disperser such as a three-roll mill or a sand mill, and then adjust the viscosity so that it is easy to imprint and the ink is suitable It is obtained by adding the remaining resin and solvent for adjustment. Hereinafter, the present invention will be described in more detail based on examples.

【Example】

 Example

76 parts of coconut oil in a 4-necked flask equipped with a stirrer,
Pentaerythritol (7 parts) and sodium hydroxide (0.05 parts) were charged, a transesterification reaction was carried out at 240 ° C. under a nitrogen stream, and then 17 parts of isophthalic acid was charged and further reacted to obtain an alkyd resin A. Similarly, the raw materials were changed to obtain alkyd resins B, C, D and E. Table 1 shows the charged amount together with the alkyd resin A.

[0016]

[Table 1]

Example 1 55 parts of resin A, 10 parts of motor oil, 10 parts of palm oil
And 5 parts of furnace carbon black are mixed, and the mixture is kneaded by applying heat of 60 ° C. to 70 ° C. with a three-roll mill. Thereafter, 2 parts of resin A and 18 parts of motor oil were added for viscosity adjustment and ink concentration adjustment, and stirred with a disper to obtain a stamp ink for stencil printing.

Examples 2 to 6 and Comparative Examples 1 and 2 In the same manner as in Example 1, the resin A was changed to B, C, D and E, and the palm oil was changed to a fractional distillation product of palm oil or a motor oil. Created the ink. Table 2 shows a summary of the ink composition.

[0019]

[Table 2]

Table 3 shows the viscosity values and the storage stability of the inks shown in Examples and Comparative Examples. The test conditions of the test items in Table 3 are as follows. BH type 2 rpm: Viscosity of BH type viscometer at 2 rpm
Shear rate 0.5 / sec Cone plate: Cone plate viscometer Shear rate 0.
5 / sec Cooling acceleration: Repeat -20 ℃ for 6 hours, 60 ℃ for 6 hours

[0021]

[Table 3]

From the above, the ink of the present invention in which the alkyd resin of the present invention, in particular, the alkyd resin using terephthalic acid or pentaerythritol and palm oil or fly ace LP are used more closely resembles Newtonian fluid, and the viscosity increases with time. Also, it can be seen that oil separation is suppressed and storage stability is good. In addition, the ink created in each example is shown in Figure 1.
It was filled in the stamp device shown in 1 above, and after making a plate using an ideal screen master (made by Ideal Chemical Co., Ltd.) as a stencil sheet, it was imprinted on a high-quality paper. When the printed matter was rubbed with an eraser immediately after printing, the paper of the example had less paper stain than the paper of the comparative example, and the ink hardly rubbed off.

[0023]

The stamp ink for a stencil printer of the present invention has a stable viscosity both before and after plate making. for that reason,
It is possible to obtain a good printed matter for a long period of time without running out of ink, soiling the paper by separating oil, and slow drying and soiling the hands. Also, since the fixing property is good and the setting is fast, the paper is not stained with ink, and the drying is slow and the hands are not soiled.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a stamper using a stencil printing method.

[Explanation of symbols]

 1 Container filled with ink or ink impregnated body 2 Stencil base paper 3 Paper

Claims (3)

[Claims] 1. An oil length 60 to 9 obtained by condensing an aromatic polyhydric carboxylic acid, a polyhydric alcohol and a fat or oil in all the ink compositions.
30% to 97% by weight of the oil-modified alkyd resin of 0, 2% to 40% by weight of palm oil or a fractional distillation product of palm oil, 0% to 40% by weight of a solvent other than the above, and a colorant component. The stamp ink for stencil printing is characterized by comprising 1% by weight to 30% by weight. 2. The stamp ink for stencil printing according to claim 1, wherein the aromatic polycarboxylic acid is terephthalic acid. 3. The stamp ink for stencil printing according to claim 1, wherein the polyhydric alcohol is pentaerythritol.