JPH06145577A - Ink for stencil printing - Google Patents

Abstract

PURPOSE:To improve the long-term stability of the title ink which comprises a water-in-oil emulsion prepd. from a fatty-acid-modified alkyd resin. CONSTITUTION:The ink is prepd. by dispersing 85-55wt.% water phase in 15-45wt.% oil phase which contains a fatty-acid-modified alkyd resin with an oil length of 60-90, a solvent, a colorant, and an emulsifier having an HLB of 10 or lower and comprising a fatty acid ester of polyglycerin.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a printing ink for stencil printing which is excellent in emulsion stability and pigment fixing property.

[0002]

2. Description of the Related Art Water-in-oil emulsions are often used as stencil printing inks used for simple printing and the like because of their excellent drying properties. When the oil phase contains a resin component, the pigment dispersibility and the sticking property are excellent, and it becomes difficult to discolor the printed matter even if the printed matter is rubbed. Among them, the fatty acid-modified alkyd resin is preferable. However, the ink using the alkyd resin has a drawback that it lacks emulsion stability and tends to separate from the ink over time.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the temporal stability of a stencil printing ink comprising a water-in-oil emulsion containing a fatty acid-modified alkyd resin.

[0004]

The present invention provides an oil length of 60-9.
0 fatty acid modified alkyd resin, solvent, colorant and H
85-55 wt% of water phase in 15-45 wt% of oil phase containing polyglycerin fatty acid ester-based emulsifier of LB 10 or less
The present invention relates to a stencil printing ink characterized by being dispersed.

The stencil printing ink of the present invention is a water-in-oil emulsion ink in which an aqueous phase is finely dispersed in the oil phase.
The oil phase mainly contains an alkyd resin, a colorant, a solvent and an emulsifier. The oil phase constitutes 15-45% by weight of the total ink.

The alkyd resin of the present invention comprises fatty acids, polybasic acids and polyhydric alcohols as constituents. As the fatty acid, non-drying oil or non-drying oil such as palm oil, palm oil, olive oil, castor oil, rice sugar oil, cottonseed oil and the like, and these fatty acids are preferable because they do not easily cause plate clogging due to drying on a printing machine. As the polybasic acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, saturated polybasic acid such as citrahydrophthalic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, anhydrous Unsaturated polybasic acids such as citraconic acid can be used.

As the polyhydric alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol,
Trimethylene glycol, tetramethylene glycol,
Glycerin, trimethylolpropane, neopentyl glycol, diglycerin, triglycerin, pentaerythritol, dipentaerythritol, mannitol, sorbit, etc. can be used. The oil length of the alkyd resin is given as the weight percent of the resin when the fatty acid was present in triglyceride. The oil length is preferably 70 to 80, shorter than 60,
Alternatively, if it is longer than 90, the dispersibility of the pigment becomes poor, which is not preferable.

For the alkyd resin, the raw material is appropriately selected so that the oil length is within the above range, and 18
It can be obtained by transesterification or esterification at 0 to 260 ° C. The alkyd resin is used in an amount of 2 to 20% by weight, preferably 3 to 15% by weight, based on the total ink. 20% by weight of alkyd resin used
If the amount is larger, the ink becomes harder, which is not preferable.
If it is less than 2% by weight, the pigment dispersibility and the ink sticking property to paper are deteriorated, which is not preferable.

The emulsifier is a polyglycerin fatty acid ester system having an HLB of 10 or less, preferably 1 to 7, the polyglycerin preferably has a polymerization degree of 6 to 10, and the fatty acid is a saturated or unsaturated fatty acid having 10 to 26 carbon atoms. Particularly preferred are oleic acid, isostearic acid, lauric acid, erucic acid and the like. The emulsifier is used in an amount of 1 to 10% by weight based on the total ink.

As the solvent, castor oil, dehydrated castor oil,
Vegetable oil such as linseed oil, tall oil, soybean oil, boiling point 200
Petroleum solvent above ℃, spindle oil, liquid paraffin,
Petroleum oils such as motor oils, gear oils and machine oils, and synthetic oils obtained by polymerizing unsaturated hydrocarbons such as ethylene, propylene and butene can be used. The solvent is contained in 5 to 25% by weight in the total ink. As the colorant, it is possible to use an inorganic pigment such as carbon black, titanium dioxide or navy blue, an organic pigment such as a phthalocyanine pigment, an insoluble azo pigment, a soluble azo pigment or a quinacridone pigment. Colorant content is 1 to 20% by weight, based on the total ink
Is.

In addition to water, polyhydric alcohols such as ethylene glycol, glycerin and propylene glycol can be added to the aqueous phase in order to prevent freezing and evaporation.
Further, in order to improve the emulsion stability of the ink, a water-soluble polymer such as methyl cellulose or carboxymethyl cellulose, an electrolyte, and a preservative can be added. The aqueous phase accounts for 85 to 55% by weight of the total ink components.

In the stencil printing ink of the present invention, a colorant and an emulsifier are added to all or part of the oil phase component, and the mixture is kneaded and dispersed with a disperser such as a triple roll mill or a sand mill. Then, while gradually adding the water phase to the oil phase, the mixture is emulsified with a homomixer, a disper or the like to obtain a water-in-oil emulsion. Alternatively, further treated with a colloid mill, various emulsifying and dispersing machines, or the oil phase without gradually adding the aqueous phase,
The aqueous phase may be separately metered to those dispersers and emulsified. The emulsifier may be added immediately before the emulsification step. Hereinafter, the present invention will be described in more detail based on examples.

[0013]

【Example】

Example 1 A four-necked flask equipped with a stirrer was charged with 73 parts of coconut oil, 5 parts of glycerin and 0.05 part of sodium hydroxide, and transesterified at 220 ° C. under a nitrogen stream, after which 22 parts of isophthalic acid was charged and reacted. , An alkyd resin was obtained. This alkyd resin 10 parts and No. 1 spindle oil 10
5 parts of furnace carbon and decaglyceryl pentaoleate (HLB = 3.5)
7 parts are mixed and kneaded with 3 rolls to obtain an oil phase. An aqueous phase prepared by previously mixing 1 part of sodium sulfate, 10 parts of glycerin and 57 parts of water was gradually added to this oil phase and stirred with a disper to obtain an ink for stencil printing. Using this ink, Ricoh Co., Ltd. Preport VT-3
Printing was performed using 500 (single cylinder stencil printer).
The printed matter was rubbed with paper after 6 hours to confirm discoloration.
It was very few. Further, the ink was good even after being stored at room temperature for 2 months without separation or the like.

Example 2 In the same manner as in Example 1 except that the coloring material was changed from furnace carbon to lake red and the emulsifier was changed to hexagrill triisostearate (HLB = 2.5). An ink was prepared. The color loss of the printed matter printed with this ink and the ink separation state after 2 months at room temperature were also good.

Example 3 An ink was prepared in the same manner as in Example 1 except that alkyd resin synthesized by changing palm oil to palm kernel oil in Example 1 was used. The printed matter printed with this ink had a color fading, and the ink separated state after 2 months at room temperature was good.

Comparative Example 1 In Example 1, the emulsifier was sorbitan sesquioleate 7
An ink having different parts was prepared. The printed matter printed with this ink showed good color fading, but the ink stored at room temperature for 1 month showed separation and was unusable.

Comparative Example 2 In Comparative Example 1, an ink was prepared in which the alkyd resin was changed to motor oil. This ink was in good condition even after being stored at room temperature for 2 months. However, when the printed matter was rubbed with paper, discoloration was remarkable.

Comparative Example 3 An alkyd resin was obtained in the same manner as in Example 1 except that 50 parts of coconut oil, 9 parts of glycerin, 0.05 part of sodium hydroxide, and 41 parts of isophthalic acid were mixed. 6 parts of this alkyd resin and 14 parts of No. 1 spindle oil were mixed and dissolved, and further 5 parts of furnace carbon and decaglycerin pentaoleate (HLB = 3.7) 7
Parts were mixed and kneaded using a three-roll mill, but the dispersibility of the pigment was poor and kneading was poor.

[0019]

The stencil printing ink of the present invention has an oil length of 60.
Since the alkyd resin of up to 90 is used, the pigment dispersibility and the sticking property are excellent, and the printed matter does not easily rub off. Also,
Since a polyglycerin fatty acid ester having an HLB of 10 or less is used as an emulsifier, the stability of the emulsion is good, and even if the ink is stored for a long period of time, the oil phase and the aqueous phase do not separate and the stability over time is excellent.

Claims (1)

[Claims] 1. An aqueous phase of 85 to 55% by weight is dispersed in an oil phase of 15 to 45% by weight containing a fatty acid-modified alkyd resin having an oil length of 60 to 90, a solvent, a colorant, and a polyglycerin fatty acid ester-based emulsifier having an HLB of 10 or less. An ink for stencil printing, which is characterized by being formed.