JP2895246B2 - Emulsion ink for stencil printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a long-term storage stability and a long-term storage stability by containing an acrylic resin having a three-dimensional structure in an oil phase of a W / O emulsion and being gelled in oil. The present invention relates to a stencil printing emulsion ink having excellent fixability.

[0002]

Stencil printing method using a stencil printing sheet as is known, by moving the other ink to the side from one side of the raw paper through the perforations of the stencil sheet, the such as paper This is for printing on the printed surface.

In recent years, a rotary stencil printing machine has been automated by a microcomputer or the like, and the operation thereof has been simplified, and accordingly, it has been demanded that a good printed matter can be obtained immediately after the start of printing. .

Conventionally, resins have been added for the purpose of improving the storage stability of the ink and fixing the ink to paper. As these resins, for example, phenol resins, maleic acid resins, petroleum resins, alkyd resins, and rubber derivative resins are known. However, these resins merely provide the effect of increasing the viscosity and the effect of decreasing the temperature dependence of the viscosity. Therefore, when this emulsion ink is left in a stencil printing machine, only the water content of the emulsion evaporates, so that the balance between water and oil is lost and the proportion of oil increases. As a result, the proportion of water relatively decreases, the viscosity of the emulsion ink decreases, and the ink softens.

As a result of the softening of the ink as described above, at the start of printing after standing, the ink flows out of the plate cylinder more than necessary and a large amount of ink adheres to the paper, and the printing density becomes higher than the normal printing density. In addition, the printing paper is stuck to the plate cylinder, causing the paper to fly or jam. Further, the ink transferred to the paper adheres to the printing paper, resulting in a large amount of ink set-off.

In order to solve these drawbacks, it has been attempted to increase the viscosity of a stencil printing ink using organic bentonite and to impart a certain degree of thixotropic property (Japanese Patent Application Laid-Open No. 54-23601). ),
A medium-boiling solvent is used (Japanese Patent Application Laid-Open No. 61-255967), or a medium-boiling solvent and an oxycarboxylic acid-based compound are used (Japanese Patent Application Laid-Open No. 63-16064), but none of these methods is sufficient. .

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art, and in a rotary stencil printing machine, do not increase the print density at the start of printing after standing, so that paper rolls and ink backing do not occur. An object of the present invention is to provide a stencil printing emulsion ink which does not cause transfer.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted various studies to achieve the above object. As a result, the water-in-oil emulsion ink has a three-dimensional structure in the oil. By containing an acrylic resin that becomes gel-like, the oil phase itself has properties as a thixotropic fluid, and as a result, even if the water in the emulsion evaporates, the apparent viscosity remains infinite. , Spread meter
Did not increase and found that softening could be prevented, and the present invention was reached.

The present invention comprises 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, has a three-dimensional structure in the oil phase, and contains An emulsion ink for stencil printing, characterized by containing an acrylic resin that becomes a gel.

The oil phase comprises an oil component, an emulsifier, a colorant, a resin and the like. The aqueous phase comprises water, a water-soluble resin, an electrolyte, an antifungal agent, an antioxidant, a water evaporation inhibitor and the like. Known components that do not inhibit the formation of an emulsion are used as these components.

Further, the emulsion ink for stencil printing of the present invention improves the storage stability of the ink, improves the sticking of the ink to paper, and improves the finish of the printed matter.
In order not to increase the print density at the start of printing after standing, to prevent the paper from rising and the ink to set off, the oil phase has a three-dimensional structure and a gel in the oil used for the oil phase. Acrylic resin in a state of 0.5 to the total amount of oil phase
% By weight, preferably 1.5% by weight or more.

The structure of this resin is a three-dimensional structure, which is fundamentally different from a linear polymer, in which molecules are easily entangled with each other, and are in a "gel" state which swells without being dissolved. Therefore, the oil phase can have the properties of a thixotropic fluid.

The above-mentioned resins include the following. Lauryl methacrylate (LMA), glycidyl methacrylate (GMA), methacrylic acid (MA
A), a copolymer of methyl methacrylate (MMA) (hereinafter referred to as RPR-AB)

[0014]

Stearyl methacrylate (SMA), glycidyl methacrylate (GMA), methacrylic acid (M
AA), a copolymer of methyl methacrylate (MMA) (hereinafter referred to as RPR-FC)

[0016]

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

As the emulsifier used to constitute the water-in-oil emulsion ink, a nonionic surfactant is preferable, and 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, higher alcohols and alkylphenols
And ethylene oxide adducts such as fatty acids,
Two or more of these low and high HLB values are combined, and the HLB value can be adjusted to obtain a highly stable emulsion.

Polyhydric alcohols such as ethylene glycol, sorbitol and glycerin, and polyethylene glycol are used as the evaporation inhibitor and the antifreezing agent.

As the coloring agent, general inorganic and organic pigments can be used. For example, in the case of black, so-called carbon black such as furnace black, channel black and acetylene black, and in the case of blue As for the phthalocyanine, known ones such as phthalocyanine bleed and red brilliant fast scarlet are used.

Examples of the antiseptic / antifungal agent include aromatic hydroxy compounds and chlorinated products thereof, salicylic acid, phenols, methyl p-oxybenzoate, ethyl p-oxybenzoate, sorbic acid, dehydroacetic acid and the like. Is used.

The emulsion ink for stencil printing of the present invention can be produced, for example, by adding a colorant and an emulsifier to the above-mentioned oil component and mixing them, and then adding a solution in an aqueous phase to emulsify.

[0023]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. (Parts listed below are parts by weight.)

Example 1 (colorant) channel black 6 parts (solvent) # 30 motor oil 28 parts (resin) lauryl methacrylate, glycidyl methacrylate, methacrylic acid, methyl methacrylate 2 parts of polymer (Emulsifier 1) 4 parts of sorbitan sesquioleate (Emulsifier 2) 2 parts of polyoxyethylene sorbitan monooleate 2 parts dispersed in a roll mill to form an oil phase, and (water) ion exchange A mixed solution of 54 parts of water (antifreezing agent), 4 parts of ethylene glycol (antiseptic and fungicide), and 0.2 parts of ethyl P-oxybenzoate is added dropwise to the above oil phase and emulsified to emulsify the ink for stencil printing. Obtained.

Using this ink, sufficient printing was performed with a heat-sensitive stencil printing machine (Preport SS955, manufactured by Ricoh Co., Ltd.) to allow the ink to spread through the printing machine, and its print density (Macbeth density) after standing for 24 hours. RD-914), set-off state, and flow value. Example 2 and Comparative Examples 1 and 2 were performed according to the prescription shown in Table 1, and evaluated in the same manner as in Example 1.

Table 1 Example of implementation Comparison Comparison Example 1 Example 2 Example 1 Example 2 Colorant Channel Black 6 666 6 Solvent # 30 motor oil 28 28 28 0 # 40 motor oil 0 0 28 Resin RPR -AB 2 0 0 0 RPR-FC 0 2 0 0 Emulsifier Sorbitan sesquioleate 4 4 4 4 Polyoxyethylene sorbitan monooleate 2 2 2 2 Ion-exchanged water 54 54 54 54 Antifreeze agent Ethylene glycol 4 4 4 4 Preservative and fungicide Ethyl p-oxybenzoate 0.2 0.2 0.2 0.2 Image density Before leaving 1.00 1.03 1.23 1.05 After leaving: 5th sheet 0.95 0.98 1.20 1.10 〃: 10th sheet 1.02 1.05 1.28 1.22 〃: 100th sheet 1.01 1.02 1.23 1.09 〃: 1000th 0.99 1.04 1.24 1.04 Offset Before leaving ◎ ○ △ ○ After leaving: 5th ◎ ◎ △ ○ 〃: 10th ◎ ○ × △ 〃: 100th ◎ ○ △ ○ 〃: 1000 Sheet ◎ ○ △ ○ Flow value Before leaving 28.5 28.9 31.5 29.7 After placing 28.7 28.8 32.6 30.6 Table 1 Note; ◎: almost none, ○: slightly, △: noticeable, ×: quite noticeable

[0027]

The emulsion ink for stencil printing of the present invention does not cause a decrease in ink viscosity even after several days of standing. Therefore, when performing rotary stencil printing using the ink of the present invention, even at the start of printing after standing, increase in printing density due to excessive outflow of ink, soaring of paper, that is, without causing ink set-off, etc. It is possible to quickly return to the normal operation state.

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,
An emulsion ink for stencil printing, characterized in that the oil phase has a three-dimensional structure and contains an acrylic resin which becomes gel-like in oil.