JP3071263B2 - 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 a W / O emulsion ink for stencil printing, and more particularly to a W / O type stencil printing ink which ensures the stability of the emulsion for a long period of time so that a large number of high quality images can be always obtained. / O emulsion ink.

[0002]

2. Description of the Related Art In a stencil printing system, a stencil printing paper is used, and ink is transferred from one side of the stencil printing plate to the other side through a perforated portion formed by making a stencil on the stencil printing paper. And the like to perform printing on the surface of the printing substrate.

By the way, the conventionally used ink (emulsion ink for stencil printing) generates mold and bacteria in the ink when stored for a long period of time. When these molds and bacteria are generated, the stability of the emulsion is deteriorated, and water separation and oil separation occur, which adversely affects printed matter. However, in order to prevent the generation of such molds and bacteria, it has been proposed to attach a disinfectant substance such as a halogenated acetanilide or an organotin compound to the ink (JP-A-46-7).
802, JP-A-57-202360, JP-A-5-202360
Publications such as No. 9-108067). However, these bactericide substances are questionable for their long-lasting effect, and the fact is that stencil printing inks to which such substances have been added do not have sufficient emulsion stability.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a stable stencil printing W / O emulsion ink in which molds and bacteria do not form in the ink even when stored for a long period of time.

[0005]

The present invention provides a W / O emulsion ink for stencil printing in which at least a colorant, an emulsifier and an aqueous phase are dispersed in an oil phase, wherein a nonionic surfactant is used as the emulsifier. The aqueous phase contains an isothiazoline compound or a mixture of a triazine compound and a pyridine compound as an antiseptic / antifungal agent in an amount of 0.01 to 1.0% by weight of the total amount of the aqueous phase. It is characterized by having.

Although the present inventors have conducted many studies and studies on emulsion inks for stencil printing,
It was confirmed that both the isothiazoline-based compound and the mixture of the triazine-based compound and the pyridine-based compound effectively acted as an antiseptic / antifungal agent and could maintain the stability of the emulsion for a long period of time. The present invention has been made based on such findings.

Hereinafter, the present invention will be described in more detail. The emulsion ink for stencil printing of the present invention has an oil phase of about 10
This is a water-in-oil emulsion comprising 50% by weight and about 90 to 50% by weight of an aqueous phase, and the aqueous phase contains a certain amount of the above or any of them as a preservative / antifungal agent.
Here, the proportion of the specific antiseptic / antifungal agent in the aqueous phase is suitably 0.01 to 1.0% by weight, and more preferably 0.1 to 0.3% by weight. When the amount is less than 0.01% by weight, the persistence of the effect is small. On the other hand, when the amount is more than 1.0% by weight, the stability of the emulsion deteriorates and the ink storage stability is hindered. .

In the present invention, non-drying oils such as olive oil, peanut oil, salad oil, machine oil, spindle oil and kerosene, and mineral oils are used as the solvent for forming the oil phase.

As an emulsifier used for forming a water-in-oil emulsion ink, a nonionic surfactant is preferable. Specifically, sorbitan higher fatty acid esters (for example, sorbitan monolaurate, sorbitan monopalmirate) , Sorbitan monostearate, sorbitan tristearate, sorbitan monooleate,
Sorbitan trioleate, sorbitan sesquioleate, etc.), fatty acid monoglycerides, and ethylene oxide adducts such as higher alcohols, alkylphenols, and fatty acids. In the present invention, two or more of those having a low HLB value and one having a high HLB value are combined, and the HLB value is adjusted to obtain a highly stable emulsion.

Further, as the coloring agent, general inorganic and organic pigments can be used. For example, carbon black such as furnace black, channel black and acetylene black for black, phthalocyanine blue for blue, and the like. In the case of red, a known material such as brilliant fast scarlet is used.

In addition to these, polyhydric alcohols such as ethylene glycol, sorbitol, and glycerin, and polyethylene glycol are added to the oil phase as needed.

[0012] The emulsion ink for stencil printing of the present invention comprises, for example, adding a colorant and an emulsifier to the oil component, mixing the resulting mixture, and then adding an aqueous phase solution containing the above-mentioned antiseptic and antifungal agent according to the present invention. It can be produced by adding and emulsifying. The water phase may contain conventionally known water-soluble resins, electrolytes, antifreezing agents, antioxidants and the like in addition to the preservative / antifungal agent and water.

By the way, the above-mentioned "isothiazoline compound" is a compound represented by the formula 1, its isomer and a compound having their skeleton.

Embedded image

The above-mentioned "triazine-based compound" is a six-membered heterocyclic ring containing three nitrogen atoms (triazine compound).
And a compound having the skeleton thereof. Specific examples of the triazine-based compound include 1,2,3-triazine 1,2,4-triazine 1,3,5-triazine and the like.

The above-mentioned "pyridine compound"
Is a six-membered heterocyclic compound containing 1 nitrogen atom (pyridine) and a compound having a skeleton thereof.

[0016]

Next, examples and comparative examples will be described. Parts here are by weight.

Example 1 Colorant (channel black) 6 parts Solvent (# 30 motor oil) 30 parts Emulsifier 1 (sorbitan sesquioleate) 4 parts Emulsifier 2 (polyoxyethylene sorbitan monooleate) 2 parts Disperse the oil phase in this roll mill to obtain an oil phase, and further add water (ion-exchanged water) 54 parts Antifreeze (ethylene glycol) 4 parts Preservative / antifungal agent (isothiazoline compound) 0.2 part To prepare a W / O type stencil printing emulsion ink. Apply this ink to 3
Even after storage at 0 ° C. and 75% RH for 6 months, no mold or bacteria was found in the ink, and there was no separation of the ink, and there was no change from the initial one. Further, when this ink was subjected to printing on a heat-sensitive stencil printing machine Preport SS-950 manufactured by Ricoh Company, a clear stencil print was obtained. Table 1 shows the evaluation results.

Examples 2 to 4 and Comparative Examples 1 to 4 Seven more types of emulsion inks for W / O stencil printing were prepared in the same manner as in Example 1 except that the materials used were variously changed. When these inks were evaluated, the results shown in Table 1 were obtained.

[0019]

[Table 1] * 1) Halogenated acetamide * 2) 2-Bromo-2-nitro-1,3-butanediol * 3) Regarding storage stability, ◎ indicates extremely good, は indicates good, Δ indicates poor, and × indicates extremely poor. (Hereinafter the same).

Comparative Example 5 An emulsion ink for stencil printing was prepared in the same manner as in Example 1 except that 0.2 parts of an antiseptic / antifungal agent (isothiazoline compound) was not contained in the aqueous phase but in the oil phase. .
Table 2 summarizes the evaluation of these.

Comparative Example 6 An emulsion ink for stencil printing was prepared in the same manner as in Example 1 except that the emulsifier was changed to 6 parts of polyoxyethylene alkyl ether phosphoric acid (anion type). Table 2 summarizes the evaluation of these.

[0022]

[Table 2]

Examples 5 to 8, Comparative Examples 7 and 8 In Examples 1 to 4, instead of the isothiazoline compound which is a preservative and fungicide contained in the aqueous phase, a triazine compound and a pyridine compound were used. After using the mixture, emulsion inks for stencil printing were prepared in exactly the same manner as in Examples 1-4 and Comparative Examples 3 and 4. These emulsion inks of the present invention and comparative emulsion inks exhibited almost the same evaluations as in Examples 1 to 4 and Comparative Examples 3 and 4.

Comparative Example 9 A stencil plate was prepared in the same manner as in Example 5 except that 0.2 parts of an antiseptic / antifungal agent (mixture of a triazine compound and a pyridine compound) was not contained in the aqueous phase but contained in the oil phase. An emulsion ink for printing was prepared. Table 3 summarizes the evaluations.

Comparative Example 10 An emulsion ink for stencil printing was prepared in the same manner as in Example 5 except that the emulsifier was changed to 6 parts of polyoxyethylene alkyl ether phosphate (anion type). Table 3 summarizes the evaluations.

[0026]

[Table 3]

[0027]

As is clear from the description of the examples, W / W contains a specific amount of a preservative / antifungal agent in an aqueous phase in a certain amount.
O-type emulsion inks not only have good storage stability, but also produce good stencil prints.

Continued on the front page (72) Inventor Fumiaki Arai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Naoto Shimoda 1-3-6 Nakamagome, Ota-ku, Tokyo Co., Ltd. In Ricoh (58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 11/00-11/20 A01N 43/78 A01N 43/66-43/707 A01N 43/40 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] 1. A W / O emulsion ink for stencil printing in which at least a colorant, an emulsifier and an aqueous phase are dispersed in an oil phase, wherein a nonionic surfactant is used as the emulsifier, and An isothiazoline compound, or
An emulsion ink for stencil printing, comprising a mixture of a triazine compound and a pyridine compound as an antiseptic / antifungal agent in a range of 0.01 to 1.0% by weight of the total amount of the aqueous phase.