JP2585927C - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emulsion ink for stencil printing, and to a high temperature emulsion (50 to 7).
0 ° C.) It relates to an emulsion ink for stencil printing which is excellent in storage stability and excellent in ink fluidity and image quality temperature dependency. 2. Description of the Related Art As is well known, a stencil printing method uses a stencil printing paper, and moves ink from one side of the base paper to the other side through a perforated portion of the stencil printing paper. The printing is performed on the surface of the printing substrate. 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. On the other hand, storage conditions are sometimes 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, the water phase of emulsion inks is often used without thickening water, and the viscosity of the oil phase is increased to ensure stability, and a resin is used for that purpose. This was very difficult (JP-A-61-255967). Furthermore, these inks exhibit sufficient stability when stored at room temperature (40 ° C. or lower), but when left at 50 ° C. or higher, the emulsion may be broken, causing a problem that the ink is energized and water is separated. There were many. Further, as resins used for improving stability, for example, phenol resins, maleic acid resins, petroleum resins, alkyd resins, rubber derivative resins and the like are known.
In order to obtain sufficient stability with these resins, many resins are required. Moreover,
In this case, the fluidity of the ink may be significantly impaired, and as a result, a uniform image density may not be obtained. Further, since a resin, which is a polymer compound having a high temperature dependency, is blended into the ink, the temperature dependency of the obtained image quality also increases. [0005] Accordingly, an object of the present invention is to eliminate the disadvantages of the prior art, to provide a rotary stencil printer with excellent emulsion high temperature (50 to 70 ° C) stability, and An object of the present invention is to provide an emulsion ink for stencil printing which has excellent ink fluidity and temperature dependency of image quality. Means for Solving the Problems As a result of intensive studies, the present inventors have used a surfactant having a specific HLB in an oil phase and a thickened aqueous phase. The inventors have found that a water-in-oil emulsion ink meets the above-mentioned object, and have completed the present invention. That is, according to the present invention, a water-in-oil emulsion composed of about 10 to 50% by weight of an oil phase and about 90 to 50% by weight of an aqueous phase, and the HL of the surfactant in the oil phase
The emulsion ink for stencil printing, wherein B is 3.0 to 5.5, the aqueous phase is thickened, and the viscosity is 15 to 350 poise. In the emulsion ink for stencil printing of the present invention, the HLB (hydrophilic-lipophilic balance) of the surfactant in the oil phase is from 3.0 to 5.5, the viscosity of the aqueous phase is increased, and the viscosity is increased. High temperature (50-70 ° C.) of the emulsion because it was 15-350 poise
It is excellent in stability and also excellent in fluidity of ink and temperature dependency of image quality. The reason is that when the HLB of the surfactant in the oil phase is in the range of 3.0 to 5.5, the aqueous phase, which is the internal phase of the emulsion, is given viscosity to prevent coalescence of the emulsion, It is presumed that this improves the high-temperature storage stability and eliminates the use of a large amount of resin, and thus provides excellent ink fluidity and image quality temperature dependency. Hereinafter, the present invention will be described in more detail. The emulsion ink for stencil printing of the present invention comprises a water-in-oil emulsion composed of about 10 to 50% by weight of an oil phase and about 90 to 50% by weight of an aqueous phase, wherein the oil phase is composed of an oil component, an emulsifier, and the like. And the aqueous phase is water, an electrolyte, an antiseptic / fungicide,
It is composed of an antioxidant, a water evaporation inhibitor, a water-soluble polymer 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. The surfactant (emulsifier) used in the present invention is preferably a nonionic surfactant and has an HLB of 3.0 to 5.5. 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 combination system, the HLB of the surfactant does not need to be within the above range, and the HLB in the mixed state may be within the above range. For example, if the HLB is 10
What is necessary is just to use together the thing of 3-4, and to make HLB in a mixed state 3.0-5.5. Specific examples of the surfactant include, for example, higher sorbitan fatty acid esters, higher polyoxyethylene sorbitan fatty acid esters, fatty acid monoglycerides, fatty acid diglycerides, and higher alcohols, alkylphenols, ethylene oxide adducts of fatty acids, and the like. And those whose HLB is within the above range, or those whose HLB falls within the above range in a combined system, are used. [0012] 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, sorbic acid, dehydroacetic acid and the like are used. In the present invention, the aqueous phase is thickened, and the viscosity of the aqueous phase is 15 to 350.
It is preferably poise. Therefore, in the present invention, a water-soluble polymer is contained in the aqueous phase. 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 derivatives, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polyethylene oxide, polyvinyl methyl ether, etc. Forming polymer and the like are used. Among them, acrylate resins and acrylate resin derivatives such as sodium polyacrylate and triethanolamine polyacrylate are particularly preferable because they effectively exhibit a thickening effect with a small amount of use. That is, according to the acrylic resin (derivative),
Since the cost is lower than that of other water-soluble resins, and a large amount of water-soluble resin does not need to be used, deterioration of the drying property can be suppressed. In the present invention, 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 the thickening accelerator used in the case of acrylic acid 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 disperser 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. EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. In addition, all the parts shown below are based on weight. Example 1 A raw material having the following formulation was used. (Coloring agent) Furnace carbon black 4 parts (emulsifier) Sorbitan sesquioleate 5 parts HLB: 3.7 (solvent) Paraffin oil 16 parts (water) Deionized water 34.17 parts Aqueous phase viscosity: 180 poise (antifreeze) Ethylene glycol 10.00 parts (water-soluble polymer) 1% polyacrylic acid aqueous solution 30.00 parts (thickening accelerator) 10% sodium hydroxide aqueous solution 0.83 parts [0019] Pigment dispersion is prepared by adjusting carbon black, paraffinic oil and surfactant,
Further, if necessary, the alkyd resin is kneaded with three rolls, followed by addition of a small amount of oil and a pigment dispersion or, if necessary, a gel varnish such as a rosin-modified phenol resin, and uniformly mixing them with a mixing stirrer. The oil phase was used as the oil phase. The thickening aqueous phase is prepared by immersing the acrylic acid polymer in water overnight, adding ethylene glycol thereto, and then adding an aqueous solution of sodium hydroxide as a thickening accelerator with stirring. The aqueous phase was used. Next, the aqueous phase was added to the oil phase and emulsified to obtain a stencil printing emulsion ink. Examples 2 to 8 and Comparative Examples 1 to 3 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 and aqueous phase viscosity. [Table 1] Using the emulsion inks obtained in the above Examples and Comparative Examples, using a thermosensitive stencil printing machine [Preport VT3500, manufactured by Ricoh Co., Ltd.], sufficient printing was performed, and the ink was allowed to pass through the printing machine. Printing was performed at environmental temperatures of 10 ° C, 20 ° C, and 30 ° C. At this time, the print density of the printed matter was measured by a reflection type optical densitometer (manufactured by Macbeth). Further, the ink was stored in an environment of 60 ° C., the amount of electricity was measured from the resistance value of the tester, and the storage stability against water separation was evaluated. The ink fluidity was indicated by a 1-minute value (23 ° C.) using a spread meter (the size of the diameter 1 minute after the start of the test).
The results are summarized in Table 2. The viscosity of the aqueous phase was measured using a Viscodestar (manufactured by Rion) (23 ° C.). [Table 2] High-temperature storage stability:…: no water separation at 60 ° C. for 90 days or more…: no water separation at 60 ° C. for 60 to 90 days Separation From the amounts of the water-soluble resins used in Examples 1 and 7 in Table 1, it can be seen that the use of the acrylate resin can reduce the amount of the water-soluble resin used. As is clear from the results of Examples 1, 3, 8 and Comparative Example 2 in Table 2, the higher the viscosity of the aqueous phase, the better the high-temperature storage stability of the emulsion ink of the present invention. 3 shows that not only the storage stability at high temperature but also the ink fluidity and the image quality temperature dependency are excellent. Furthermore, from the results of Examples 1 and 2 and Comparative Example 1,
It can be seen that when the HLB is 6.2 or more, the high-temperature storage stability deteriorates. The emulsion ink for stencil printing according to claim 1, wherein the HLB of the surfactant in the oil phase of the water-in-oil emulsion is in the range of 3.0 to 5.5, and the aqueous phase Is thickened and the viscosity is 15 to 350 poise, and as is clear from the description of the examples, the emulsion is more surely excellent in high temperature (50 to 70 ° C.) stability,
In addition, the ink has excellent fluidity and temperature dependency of image quality. The emulsion ink for stencil printing according to claim 2 has a configuration in which the aqueous phase of the emulsion contains an acrylic acid resin (derivative), so that it can be used in a smaller amount than in the case of other water-soluble resins. In addition to achieving the cost reduction, the effect of suppressing the deterioration of the drying property is added.

Claims (1)

Claims: 1. A water-in-oil emulsion comprising about 10 to 50% by weight of an oil phase and about 90 to 50% by weight of an aqueous phase, wherein the HLB of the surfactant in the oil phase is 3%. .
An emulsion ink for stencil printing, wherein the emulsion ink has a viscosity of from 0 to 5.5, and the aqueous phase has a viscosity of 15 to 350 poise. 2. The emulsion ink for stencil printing according to claim 1, wherein the aqueous phase contains an acrylic resin or a derivative thereof.