JP3191446B2 - 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 stencil printing ink having excellent emulsion stability and pigment fixability, low odor and low toxicity.

[0002]

2. Description of the Related Art As a stencil printing ink used for simple printing and the like, a water-in-oil type emulsion having excellent drying properties is often used. A stencil printing ink of a water-in-oil type emulsion is a solvent in which water droplets are finely dispersed in an oil phase containing a solvent or a resin and a solvent. Examples of the resin include alkyd resin, rosin-modified alkyd resin, and rosin-modified phenol resin. And petroleum resins, and spindle oils containing aromatic components have been used as solvents because of their good solubility in these resins. However, the aromatic component in the solvent has a disadvantage that it has an odor and deteriorates the environment in which the printing press is placed. In general, aromatic solvents are highly irritating to the skin, and this may cause a problem when the stencil printing ink comes into contact with the skin at the time of use. Replacing with a non-aromatic paraffin-based or naphthenic-based solvent lowers the solubility of the resin and causes a problem that it is difficult to form an ink. Further, stencil printing inks containing no resin have poor pigment fixation properties, and the pigments are not sufficiently retained in the printed ink layers.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a stencil printing ink excellent in safety and hygiene. Still another object of the present invention is to provide a stencil printing ink excellent in pigment fixability.

[0004]

According to the present invention, there is provided an iodine value of 5 to 15% by weight of a solvent having an aromatic solvent component of 0.5% by weight or less, an oil length of 60 to 90%, a hydroxyl value of 20 to 100, and Oil phase 1 containing 3 to 15% by weight of an alkyd resin of 80 or less
The present invention relates to a stencil printing ink in which 85 to 55% by weight of an aqueous phase is dispersed in 5 to 45% by weight.

[0005] The stencil printing ink of the present invention is a water-in-oil emulsion ink in which an aqueous phase is finely dispersed in an oil phase. The oil phase mainly comprises an organic solvent and an alkyd resin dissolved in the organic solvent. Organic solvent is 0.5% by weight of aromatic solvent
It consists of the following solvent components: paraffinic and naphthenic hydrocarbon components. The solvent preferably contains a fraction of 350 ° C. or less. Examples of such non-aromatic solvents include commercially available products such as AF Solvent and Isosol (trade names, manufactured by Nippon Oil Co., Ltd.), and Exsol (trade name, manufactured by Exxon Chemical Co., Ltd.).

[0006] The alkyd resin of the present invention comprises fats and oils, a polybasic acid and a polyhydric alcohol. As fats and oils,
Non-drying oil or semi-drying oil such as coconut oil, palm oil, olive oil, castor oil, rice bran oil, cottonseed oil and the like, and these fatty acids are preferable in order to make the iodine value 80 or less, but soybean oil, linseed oil, kiri oil, etc. Drying oil and the like can be partially used.

The polybasic acids include saturated polybasic acids such as phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid and tetrahydrophthalic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid And unsaturated polybasic acids such as citraconic anhydride. Polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, glycerin, trimethylolpropane, neopentyl glycol, diglycerin, triglycerin, pentaerythritol, Pentaery slit, mannit, sorbit, etc. can be used.

[0008] The oil length of the alkyd resin is expressed as a percentage by weight in the resin when the fatty acid in the fat or oil is present as triglyceride. The oil length is preferably from 70 to 80, and if it is shorter than 60, the solubility in a non-aromatic solvent is reduced. If the hydroxyl value of the alkyd resin is less than 20, or 10
If the value is larger than 0, the stability of the emulsion decreases, which is not preferable. On the other hand, if the iodine value is larger than 80, a film is easily formed on the plate cylinder of the printing press, and if left for a long period of time, the screen of the plate cylinder is clogged, which is not preferable.

[0009] The alkyd resin can be obtained by a transesterification reaction and an ester reaction at 180 to 260 ° C in the presence of an alkali catalyst by appropriately selecting raw materials so that the oil length, hydroxyl value and iodine value fall within the above ranges. . The oil phase constitutes 15 to 45% by weight based on the total stencil printing ink, and contains a colorant, an emulsifier and the like in addition to the non-aromatic organic solvent and the alkyd resin. Examples of the coloring agent include inorganic pigments such as carbon black, titanium dioxide and navy blue, and organic pigments such as a phthalocyanine pigment, an insoluble azo pigment, a soluble azo pigment, and a quinacridone pigment.
The content of the colorant is 1 to 20% by weight based on the total ink.

Examples of the emulsifier include HLB such as sorbitan fatty acid ester, glycerin or polyglycerin fatty acid ester, and polyoxyethylene fatty acid ester.
Those below 0 can be used. The water phase is made of ethylene glycol, other than water, to prevent freezing and suppress evaporation.
Polyhydric alcohols such as glycerin and propylene glycol can be added. In order to improve the emulsion stability of the ink, a water-soluble polymer such as methylcellulose and carboxymethylcellulose, a preservative, an electrolyte and the like can be added.

[0011] The stencil printing ink of the present invention is obtained by adding a colorant to all or a part of an oil layer component, and using a three-roll mill,
The mixture is kneaded and dispersed by a disperser such as a sand mill, and while adding an emulsifier and gradually adding water, a water-in-oil emulsion is formed by a disperser such as a homomixer, a sand mill, and a disper. The particle size of the finely dispersed aqueous phase is preferably 50 μm or less. Hereinafter, the present invention will be described in more detail based on examples.

[0012]

EXAMPLES A four-necked flask equipped with a stirrer was charged with coconut oil (76 parts), pentaerythritol (7 parts) and sodium hydroxide (0.05 part), and subjected to a transesterification reaction at 240 ° C. under a nitrogen gas stream. Then, the mixture was further reacted to obtain an alkyd resin. The hydroxyl value of this resin is 50,
The iodine value was 10 or less. 10 parts of this resin, Nisseki A
F Solvent 5 (paraffin solvent) 10 parts are mixed,
Further, 5 parts of furnace carbon black and 5 parts of sorbitan sesquioleate are mixed, and the mixture is continuously meated with three rolls to form an oil phase. This oil phase was stirred and emulsified with a disper while gradually adding an aqueous phase in which 1 part of sodium sulfate, 10 parts of glycerin and 59 parts of water were previously mixed, to obtain a stencil printing ink. Using this ink, Ricoh Preport V
There was no problem when printing was performed using T-3500 (single cylinder type stencil printing machine). 4 with this ink added
After being left for 8 hours, printing was resumed, but the printing was good without clogging of the plate. Further, the odor was very small, and the stability over time of the ink (after leaving it at room temperature for 2 months) was good.

Examples 2 and 3 and Comparative Examples 1 to 5 In the same manner as in Example 1, inks were prepared by changing the alkyd resin and the solvent, and evaluated. Table 1 shows the results.

[0014]

[Table 1]

[0015]

The stencil printing ink of the present invention does not contain an aromatic solvent, and therefore does not have an odor peculiar to the aromatic solvent.
It does not degrade the environment in which the printing press is placed and has excellent hygiene. In addition, since the specific alkyd resin is used for the oil phase, the stability of the emulsion is good, so the oil phase and the aqueous phase do not separate even after long-term storage, and the printing ink can be used for a long time on a printing press. Even if printing is resumed after being left in the inserted state, clogging of the printing plate does not occur.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) C09D 11/00-11/20

Claims (1)

(57) [Claims] 1. An alkyd resin having an aromatic solvent component of 0.5% by weight or less, 5 to 15% by weight, an oil length of 60 to 90%, a hydroxyl value of 20 to 100, and an iodine value of 80 or less. 15 to 45% by weight of oil phase containing 8% by weight of aqueous phase
A stencil printing ink in which 5 to 55% by weight is dispersed.