JP3073818B2 - 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 having excellent fixability and emulsion stability.

[0002]

2. Description of the Related Art As is well known, a stencil printing system uses a stencil printing base paper, and moves ink from one side of the base paper to the other side through a perforated portion formed by making a stencil on the base paper. Printing is performed on the surface of a printing material such as paper. In recent years, the rotary stencil printing press has been automated by a microcomputer or the like, and the operation has been simplified, and accordingly, it has been demanded that a good printed matter can be obtained immediately after the start of printing in various environments. By the way, a resin is added to a conventional stencil printing ink for the purpose of improving the storage stability of the ink and improving the fixability of the ink to paper. As these resins,
For example, phenolic resin, maleic acid resin, petroleum resin, alkyd resin, rubber derivative resin and the like are known,
In reality, many resins are required to obtain sufficient stability and fixability with these resins. However, in this case, the fluidity of the ink may be significantly impaired, and as a result, a uniform image density may not be obtained, the ink may protrude from the rear end of the drum, and the obtained image quality may be deteriorated. Defects such as a decrease in temperature dependency have been recognized.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned disadvantages of the prior art, and to provide a rotary stencil printing machine with excellent fixability, emulsion stability, and temperature dependence of ink fluidity and image quality. An object of the present invention is to provide a stencil printing emulsion ink having excellent properties.

[0004]

The emulsion ink for stencil printing of the present invention comprises about 10 to 50% by weight of an oil phase and about 9 of an aqueous phase.
0 to 50% by weight of a water-in-oil emulsion, and a phenolic or alcoholic
Resin having at least one of hydroxyl groups
And a gelling agent for the resin.
Having an average molecular weight of 3,000 to 150,000, and
The phase is at a shear rate of 1 / sec after / before gelation.
It is a stencil printing emulsion ink characterized in that the viscosity ratio is 1.5 to 10 .

[0005] To achieve the above object, the present inventors have
As a result of various studies, by incorporating a resin and a gelling agent for the resin in the oil phase of the water-in-oil emulsion, excellent fixability and storage stability, and excellent ink fluidity and temperature dependence of image quality were obtained. We found that it was effective. The present invention has been made based on this.

Hereinafter, the present invention will be described in more detail. The aqueous phase of the emulsion is composed of water, an electrolyte, a fungicide, an antioxidant, a water evaporation inhibitor and the like, and the oil phase is composed of an oil component, an emulsifier and the like. Known components that do not inhibit the formation of an emulsion are used as these components.

As described above, the emulsion ink for stencil printing of the present invention contains a resin and its resin in an oil phase in order to have excellent fixability and storage stability, as well as excellent fluidity and image quality temperature dependency. The greatest feature is that it contains a resin gelling agent. The resin here preferably has at least one of a phenolic hydroxyl group and an alcoholic hydroxyl group. This is because when the resin is gelled,
This is because gelation occurs around the hydroxyl groups of the resin.

This resin has an average molecular weight of 3000-1500.
It is preferably 00, more preferably 6000 to 20000. This is because if the average molecular weight is less than 3,000, the effect on fixability and storage stability is small, and if the average molecular weight is more than 150,000, the fluidity of the ink is significantly impaired, and a uniform image cannot be obtained or stencil printing. This is because the occurrence of ink spill out from the rear end of the drum of the machine becomes remarkable.

The gelling agent used herein is Li, Na,
K, Al, Ca, Co, Fe, Mn, Mg, Pb, Z
Desirable are those which form a coordination bond with the hydroxyl group of the resin, such as organic acid salts containing metals such as n and Zr, organic chelate compounds and metal soap oligomers. For example, metal octylates such as aluminum octylate, metal naphthenates such as manganese naphthenate, metal stearate such as zinc stearate, organic chelate compounds such as aluminum diisopropoxide monoethyl acetoacetate, and aluminum oxide octoate A typical example is a metal soap oligomer such as ate. These are liable to break the gelling structure when a strong share is given to the ink, thereby not impairing the fluidity of the ink, and form a gel structure when a weak share is given or in a stationary state,
This has the effect of stabilizing the oil phase and making it difficult to change the image density due to temperature changes.

Further, it is desirable that the oil phase has a viscosity of 1.5 to 10 at a shear rate of 1 / sec after / before gelation. If the viscosity ratio is lower than this, the effect of storage stability due to gelation cannot be obtained. Conversely, if the viscosity ratio is higher than this, the gel structure cannot be sufficiently destroyed and the fluidity is impaired.

As the oil component in the oil phase used in the present invention, conventionally known oil components can be applied, for example, liquid paraffin, spindle oil, light oil, kerosene, machine oil, mineral oil of lubricating oil; olive oil, rapeseed oil And vegetable oils such as castor oil and soybean oil. In the present invention, a synthetic oil can also be used. When using synthetic oils, various compounds are available. Representative synthetic vehicles include polyisobutylene, polyisobutenes, 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 silicones (polysiloxanes), butyl substitution Examples thereof include alkyl-substituted diphenyl ethers represented by bis (p-phenoxyphenyl) ethers and phenoxyphenyl ethers.

The emulsifier used in the present invention is preferably a nonionic surfactant, such as higher sorbitan fatty acid ester, higher polyoxyethylene sorbitan fatty acid ester, fatty acid monoglyceride, fatty acid diglyceride and higher alcohol, alkylphenol, fatty acid, etc. Ethylene oxide adducts of the formula (I) are used alone or in combination of two or more of these having different HLB to prepare a highly stable emulsion.

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 carbonate.

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 / antifungal agent, for example, an aromatic hydroxy compound and its chlorinated product, salicylic acid, phenols, methyl p-oxybenzoate, ethyl p-oxybenzoate and the like, sorbic acid, dehydroacetic acid and the like are used.

The emulsion ink for stencil printing of the present invention is produced, for example, by adding a pigment, a resin, a gelling agent and an emulsifier to the above-mentioned oil component, mixing the resulting mixture, and then adding an aqueous phase solution to the mixture to emulsify the mixture. it can.

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The parts here are based on weight.

Example 1 (colorant) Furnace carbon black 5 parts (solvent) No. 7 solvent 7.5 parts Paraffin oil 5 parts (resin) Rosin-modified phenol resin (average molecular weight 12000) 8 parts (gelling agent) octyl 0.5 part of aluminum acid (Emulsifier 1) 4 parts of sorbitan sesquioleate (Emulsifier 2) 2 parts of polyoxyethylene sorbitan monooleate are dispersed with a three-roll mill to form an oil phase, and 64 parts of (water) ion-exchanged water (Anti-coagulant) A mixed solution (aqueous phase) of 4 parts of ethylene glycol was added dropwise and emulsified to obtain an emulsion ink for stencil printing.

Examples 2 to 5 and Comparative Examples 1 to 7 Emulsion inks for stencil printing were obtained in the same manner as in Example 1 using the formulations shown in Table 1.

[0019]

[Table 1]

Among these inks, the ratio of the oil phase viscosity after gelling to the oil phase viscosity before gelling at a shear rate of 1 / sec in Examples 4, 5, 5, and 7 was determined by the oil phase. Table 2 shows the ratios. In addition, Example 1 was also described.

[Table 2]

Further, using these inks, sufficient printing was performed using a commercially available thermosensitive stencil printing machine (Ricoh's Preport SS955), and the ink was allowed to pass through the printing machine. Printed at ambient temperature. At this time, the print density of the printed matter was measured by a reflection optical densitometer (RD914 manufactured by Macbeth). Further, the density after erasing the portion where the density was measured at 10 reciprocations / 10 seconds with a clock meter equipped with a register mark eraser was also measured, and the fixing rate of the ink was determined from (density after erasure) / (print density). Also, about 1 g of the ink was placed in a centrifugal sedimentation tube,
Storage stability was evaluated from the oil separation rate when centrifuged at 6300 G. The ink fluidity was indicated by a 1-minute value (23 ° C.) by a spread meter (the size of the diameter 1 minute after the start of the test). These results are summarized in Table 3.

[Table 3]

[0022]

As is clear from the description of the examples, the emulsion ink of the present invention is excellent in fixability and storage stability, as well as ink fluidity and image quality temperature dependency.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiro Koike 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (72) Inventor Hitoshi Ueda 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Hiroshi Tateishi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Keisuke Asada 3-1 Shimido, Nakanameki, Shibata-cho, Shibata-gun, Miyagi Prefecture Tohoku Ricoh Co., Ltd. (56) References JP-A-46-7802 (JP, A) JP-A-4-233980 (JP, A) JP-B-50-7483 (JP, B1) JP-B-44-2165 ( JP, B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) C09D 11/00-11/20

Claims (1)

(57) [Claims] An oil phase of about 10 to 50% by weight and an aqueous phase of about 90 to 90% by weight.
A water-in-oil emulsion consisting of 50% by weight,
And a phenol or alcohol in the oil phase.
Resins that have at least one of the hydroxyl groups
And a gelling agent for the resin.
The oil phase having an average molecular weight of 3000 to 150,000
Is the viscosity at a shear rate of 1 / sec after / before gelation.
An emulsion ink for stencil printing having a degree ratio of 1.5 to 10 .