JP2747560B2 - Emulsion ink for stencil printing - Google Patents

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 stencil printing which is excellent in storage stability at a high temperature (60.degree.

[0002]

2. Description of the Related Art As is well known, a stencil printing method uses a stencil printing paper, and transfers ink from one side of the base paper to the other side through a perforated portion of the stencil printing paper, thereby forming a printing material such as paper. This is for printing on the surface. In recent years, rotary stencil printing machines have also been automated by microcomputers and the like, and operation has become simpler.
It is demanded that a good printed matter can be obtained immediately after the start of printing in various environments.

[0003] On the other hand, storage conditions may be exposed to high temperatures, such as in a tent in summer or shipping during export, and the stability of the ink at that time is a problem. Conventionally, emulsion inks have been used in which the viscosity of the oil phase is increased in order to ensure stability, a resin is used for that purpose, and the HLB is adjusted to be from 3.5 to 6 and used. Sorbitan sesquioleate, sorbitan monooleate and the like have been favorably used (see JP-A-61-2).
55967). Further, these inks show sufficient stability when stored at room temperature (40 ° C. or lower), but when left at 50 ° C. or higher, the emulsion often coalesces and the viscosity often decreases.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an emulsion ink for stencil printing which eliminates the above-mentioned disadvantages of the prior art and is excellent in high-temperature emulsion (60 ° C.) stability in a rotary stencil printing machine. Is to do.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the HLB of the surfactant in the oil phase of the water-in-oil emulsion is set to 3.0 or less, whereby the high-temperature storage stability is obtained. Have been found to have excellent effects, and have completed the present invention.

That is, according to the present invention, a water-in-oil emulsion comprising 10 to 50% by weight of an oil phase and 90 to 50% by weight of an aqueous phase is used.
Sorbitan fatty acid ester compound or glycerol
Selected from fatty acid ester compounds ,
The HLB value is 1.5 to 3.0 ( excluding 3.0).
C ), provided is an emulsion ink for stencil printing.

[0007] The emulsion ink for stencil printing of the present invention has a HLB (hydrophilic-lipophilic balance) of a surfactant in an oil phase of 1.5 to 3.0 ( excluding 3.0 ). And the emulsion has excellent high temperature (60 ° C.) stability. The reason is that the HL of the surfactant in the oil phase
By reducing B (that is, making it lipophilic) and increasing the hydrophobicity of the interface of the emulsion, it becomes difficult for water in the emulsion to pass through the interface, and water migration does not easily occur even when the emulsion approaches. It is presumed that coalescence of emulsions is prevented, and as a result, a decrease in viscosity during high-temperature storage is suppressed.

Hereinafter, the present invention will be described in more detail. The stencil emulsion ink of the present invention has an oil phase of 10 to 50.
A water-in-oil emulsion composed of 90% by weight and an aqueous phase of 90 to 50% by weight. The oil phase is composed of an oil component, an emulsifier, and the like. Agents, antioxidants, water evaporation inhibitors, water-soluble polymers and the like. Known components that do not inhibit the formation of the emulsion are used as these components.

As the oil component in the oil phase used in the present invention, conventionally known oil components can be applied, for example, mineral oils such as liquid paraffin, spindle oil, light oil, kerosene, machine oil, lubricating oil; olive oil, rapeseed Vegetable oils such as oil, castor oil and soybean oil are used. In the present invention, a synthetic oil can also be used. When using synthetic oils, various compounds are available. Representative synthetic vehicles include polyisobutylenes, hydrogenated polydecenes, trimethylolpropane esters, neopentyl and pentaerythritol esters, di (2-ethylhexyl) sebacate, di (2-ethylhexyl) adipate, dibutyl phthalate, Fluorocarbons, silicon esters, silanes, esters of phosphorus-containing acids, liquid urea, ferrocene derivatives, hydrogenated synthetic oils, linear polyphenyls, siloxanes and silicons (polysiloxanes), butyl-substituted bis Examples thereof include alkyl-substituted diphenyl ethers represented by (p-phenoxyphenyl) ethers and phenoxyphenyl ethers.

Surfactant (emulsifier) used in the present invention
Is preferably a nonionic surfactant and has an HLB of 1.5 to 3.0 ( excluding 3.0 ). Of course, the surfactants can be used not only in a single kind but also in combination of two or more kinds. Therefore, in the case of a combined system, the HLB of the surfactant does not need to be within the above range, and the HLB in a mixed state is not required.
Should be within the above range. For example, if the HLB is between 3.5 and
A mixture of 4.5 and 1.5 to 2.5 is used, and the HLB in a mixed state is 1.5 to 3.0 ( excluding 3.0).
It may be set so as to be in Ku). Specific examples of the surfactant include, for example, sorbitan higher fatty acid ester, glycerin fatty acid ester, polyethylene fatty acid ester, decaglycerin fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene castor oil,
Polyoxyethylene hydrogenated castor oil and the like can be mentioned. Among them, those having an HLB within the above range or those having an HLB within the above range in a combined system are used.

Examples of the pigment 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 carbide.

As the evaporation inhibitor and anticoagulant in the aqueous phase used in the present invention, polyhydric alcohols such as ethylene glycol, sorbitol and glycerin, and polyethylene glycol are used. As the antiseptic / fungicide, for example, an aromatic hydroxy compound and its chlorine compound, salicylic acid, phenolic acid, methyl p-oxybenzoate, ethyl p-oxybenzoate and the like, sorbic acid, dehydroacetic acid and the like are used.

A water-soluble polymer can be used in the aqueous phase for moisturizing or thickening. Specific examples of the water-soluble polymer include, for example, natural polymers such as starch, mannan, sodium alginate, galactan, tragacanth gum, gum arabic, burlan, dextran, xanthan gum, glue, gelatin, collagen, casein; Semi-synthetic polymers such as methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxymethylstarch, carboxymethylstarch and dialdehyde starch; acrylic resins such as acrylic acid resins and sodium polyacrylate and triethanolamine polyacrylate Resin derivative, polyvinyl alcohol,
Examples include synthetic polymers such as polyvinylpyrrolidone, polyacrylamide, polyethylene oxide, and polyvinyl methyl ether.

In order to increase the viscosity of the aqueous phase, a thickening accelerator can be used in addition to the water-soluble polymer. For example, as a thickening accelerator used in combination with an acrylic resin, diisopropanolamine, di-2 (ethylhexyl) amine, triethanolamine, triamylamine, b-dimethylaminopropionitrile, dodecylamine, morpholine Examples thereof include low molecular amines such as phosphorus, alkanolamines, and the like, and inorganic bases such as sodium hydroxide, potassium hydroxide, and ammonium hydroxide.

In preparing the emulsion ink of the present invention, the oil phase is usually prepared by dispersing a pigment using a known dispersing machine and diluting the pigment with oil or another oil phase composition. A known stirrer is usually used for dilution. The aqueous phase is usually mixed with an aqueous phase composition using a stirrer. The completed oil phase and aqueous phase are easily emulsified using a known emulsifier. Production methods and means such as dispersion, dilution, and emulsification can be appropriately changed.

[0016]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. In addition, all the parts shown below are based on weight.

Example 1 Raw materials having the following formulation were used. (Colorant) Furnace carbon black 4 parts (Emulsifier) Sorbitan trioleate 6.0 parts HLB: 1.7 (Solvent) Paraffin oil 6.0 parts Low viscosity petroleum solvent 6.0 parts (Resin) Alkyd resin 8. 0 parts (water) ion-exchanged water 58.5 parts (antifreeze) ethylene glycol 10 parts (electrolyte) magnesium sulfate 1.5 parts

The pigment dispersion is prepared by kneading carbon black, paraffinic oil and surfactant, or alkyd resin with three rolls, followed by oil and pigment dispersion and, if necessary, rosin-modified. A small amount of a gel varnish such as a phenol resin was added, and the mixture was uniformly mixed with a mixing stirrer to obtain an oil phase. The aqueous phase was prepared by adding ethylene glycol to ion-exchanged water and then adding magnesium sulfate with stirring. Next, by emulsifying the oil phase with the aqueous phase,
An emulsion ink for stencil printing was obtained.

Examples 2 to 4 and Comparative Examples 1 and 2 Emulsion inks for stencil printing were obtained in the same manner as in Example 1 using the formulations shown in Table 1. Table 1 also shows HLB.

[0020]

[Table 1]

The emulsion inks obtained in the above Examples and Comparative Examples were stored in an environment at 60 ° C., and the change in viscosity over time was evaluated. The viscosity is measured using a cone-plate viscometer (H
AAKE (23 ° C., shear rate 100 l / s). The results are shown in Table 2 and FIG.

[0022]

[Table 2]

From Table 1 and FIG. 1, it can be seen that the viscosity change with time can be reduced by setting the HLB value to 3 or less. In addition, when Examples 2 and 4 are compared, it can be seen that even when the same HLB value is 3 or less, the use of a sorbitan fatty acid ester as a surfactant reduces the decrease in viscosity. Furthermore, when comparing Examples 3 and 4, the same H
It can be seen that even when the LB value is 3 or less, the use of glycerin fatty acid ester reduces the viscosity decrease.

[0024]

According to the present invention, the emulsion high temperature ( 6
0 ° C. ) An emulsion ink for stencil printing having excellent stability can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the viscosity of stencil printing emulsion inks obtained in Examples and Comparative Examples during storage at 60 ° C. and aging days.

Claims (1)

(57) [Claims] 1. An oil phase of 10 to 50% by weight and an aqueous phase of 90 to 50%.
It consists water-in-oil emulsion consisting wt%, the oil
Nonionic surfactant added in the phase is sorbitan fat
Acid ester compounds or glycerin fatty acid ester compounds
And an HLB value of 1.5
To 3.0 ( excluding 3.0 ), wherein the emulsion ink is for stencil printing.