JPH0820737A - Recording ink - Google Patents

Abstract

PURPOSE:To obtain a recording ink excellent in long-storage stability by incorporating a specific substance into a recording ink at least contg. water, a pigment, and polyvinylpyrrolidone. CONSTITUTION:A substance having a carbon fluoride group is compounded into a recording ink at least contg. water, a coloring pigment, and polyvinylpyrrolidone as a water-sol. polymer. Fluorine surfactants are examples of this substance, and nonionic or anionic fluorine surfactant can be used. Polyvinylpyrrolidone having an average mol.wt. of about 2,000-400,000 is pref. The ink may further contain an evaporation preventive, a viscosity modifier. a surface tension modifier, a pH adjuster, etc., and is used with an ink jet apparatus which jets an ink to print on a recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous recording ink having a pigment dispersed therein.

[0002]

2. Description of the Related Art Conventionally, a water-based recording ink in which a pigment is dispersed has been widely used for writing instruments or inkjet recording in which ink droplets are ejected from nozzles.

In these conventional water-based recording inks, a pigment as a colorant and a dispersant for dispersing the pigment are mainly mixed in an aqueous solution, and a pH adjusting agent and a humectant are also mixed. It has been known.

Those using a water-soluble surfactant or a water-soluble polymer as a dispersant are disclosed in JP-A-2-103274, JP-A-4-85375, and JP-A-4-180.
It is disclosed in Japanese Patent Application Laid-Open No. 973, Japanese Patent Application Laid-Open No. 4-110363, Japanese Patent Application Laid-Open No. 4-189876, Japanese Patent Application Laid-Open No. 5-239390, and the like. Further, JP-A-4-85375 discloses an example in which polyvinylpyrrolidone is used as the water-soluble polymer.

[0005]

However, polyvinylpyrrolidone, which is a water-soluble polymer, interacts with the water molecules of the solvent when left in water for a long time, and the interacting water molecules have the property of free water. Loss and a part of them are combined to cause a hydration phenomenon in which polyvinylpyrrolidone particles are aggregated with each other. For this reason, the storage stability of the recording ink in which the pigment is dispersed is poor.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a recording ink having excellent long-term storage stability.

[0007]

In order to achieve this object, in Claim 1 of the present invention, a recording ink containing at least water, a pigment as a colorant, and polyvinylpyrrolidone as a water-soluble polymer. In, it is characterized by containing a substance having fluorocarbon.

According to a second aspect of the present invention, the substance having fluorocarbon is a fluorosurfactant.

According to a third aspect of the present invention, it is used in an ink ejecting apparatus for ejecting ink to print on a recording medium.

[0010]

In the recording ink of the present invention having the above-mentioned constitution, polyvinylpyrrolidone is protected from hydration by dissolving or dispersing the substance having the fluorocarbon in the water.

[0011]

EXAMPLE An example of the present invention will be described below, but the present invention is not limited thereto.

A pigment is used as the colorant of the recording ink of the present invention, and as the pigment, inorganic pigments and organic pigments used in various coloring fields can be used.

The inorganic pigments include yellow pigments (cadmium yellow, chrome yellow, strontium yellow,
Yellow iron oxide, etc.), red pigment (Komeitan, vermilion, red iron oxide, cuprous oxide, etc.), purple pigment (cobalt violet, etc.), blue pigment (Prussian blue, etc.), green pigment (emerald green, cobalt green, chromium oxide) Etc.), white pigments (titanium oxide, zinc white, lead white, lithobon, etc.), black pigments (carbon black, graphite, etc.) and the like can be used.

The organic pigments include azo type, acridine type, phthalocyanine type, quinacridone type, anthraquinone type, indanthrene type, dioxazine type, indigo type, thioindigo type, perylene type, perinone type and isoindolenin type pigments. Can be used.

The polyvinylpyrrolidone used in the recording ink of the present invention preferably has an average molecular weight in the range of about 2,000 to 400,000, and more specifically, it has a K value of, for example, a product of ISPE or BSF. 12, 15, 17, 2
Those of 5, 30, 60, 80 and 90 can be used.

The main solvent of the recording ink of the present invention is
It is preferably water, and is preferably distilled water or ion-exchanged water because of its low viscosity, excellent safety, easy handling, low cost, and no odor. If necessary, an evaporation inhibitor, a viscosity adjusting agent, a surface tension adjusting agent, a pH adjusting agent and the like can be used.

Specifically, as an evaporation inhibitor and a viscosity modifier, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, glycerin, 1,2,6-hexanetriol, Hexylene glycol and other polyhydric alcohols, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoallyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, Dipropylene glycol monomethyl ether, tripro Polyhydric alcohol alkyl ethers such as glycol monomethyl ether, ethylene glycol monophenyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monobenzyl ether and the like can be used.

As the surface tension adjusting agent, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoallyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether. , Polyhydric alcohol alkyl ethers such as dipropylene glycol monomethyl ether and tripropylene glycol monomethyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, lower alcohols such as ethanol and 2-propanol Etc. can be used.

Examples of the pH adjusting agent include organic amines such as monoethylamine, diethylamine and triethylamine, alkanolamines such as diethanolamine and triethanolamine, and hydroxides of alkali metal elements such as sodium hydroxide and potassium hydroxide. , Carbonates of alkali metal elements such as sodium carbonate and potassium carbonate, ammonium hydroxide, and quaternary ammonium hydroxides can be used.

As the substance having a fluorocarbon used in the recording ink of the present invention, a fluorosurfactant or the like can be used.

Specifically, as the fluorine-based surfactant, a fluorine-based nonionic surfactant such as perfluoroalkyl polyoxyethylene ethanol, perfluoroalkyl alkoxylate, and fluorinated alkyl ester can be used. Further, a fluorinated anionic surfactant such as ammonium perfluoroalkyl sulfonate or potassium perfluoroalkyl sulfonate can be used.

At the time of producing the recording ink of the present invention, the pigment can be dispersed by using a ball mill, a sand mill, a roll mill, an ultrasonic homogenizer or the like to easily produce the recording ink.

Examples and comparative examples of the present invention will be specifically described.

Example 1 Carbon black 5% by weight (MA-100: manufactured by Mitsubishi Kasei Co.) Polyvinylpyrrolidone 4% by weight (K-15: ISPE Co.) Perfluoroalkyl polyoxyethylene ethanol 1% by weight (Florard FC-170C) : Sumitomo 3M) Glycerin 10% by weight Triethanolamine 2% by weight Ion-exchanged water Remaining amount.

A specific method for producing the recording ink of Example 1 will be described below. First, ion-exchanged water, glycerin,
Triethanolamine and perfluoroalkyl polyoxyethylene ethanol are mixed, and then polyvinylpyrrolidone is mixed into the mixed solution. Then, carbon black is mixed and the pigment is finely dispersed using the ball mill. Finally, if necessary, in order to remove dust and the like, a recording ink is prepared by applying pressure or reducing pressure and filtering through a filter or the like.

Hereinafter, Examples 2 and 3 of the present invention and Comparative Examples 1 to 1 will be described.
For 3 as well, a recording ink was prepared in the same manner.

Example 2 5% by weight of carbon black (Printex 90: manufactured by Degussa) 2% by weight of polyvinylpyrrolidone (K-30: manufactured by ISPE) 1% by weight of fluorinated alkyl ester (Florard FC-430: Sumitomo 3M) Propylene glycol 10% by weight Diethanolamine 2% by weight Ion-exchanged water remaining.

Example 3 Carbon black 5% by weight (Regal 250R: manufactured by Cablack) Polyvinylpyrrolidone 2% by weight (K-30: manufactured by ISPE) Potassium perfluoroalkylsulfonate 1% by weight (Florard FC-129: Sumitomo 3M) Ethylene glycol 10% by weight Ammonium hydroxide 2% by weight Ion-exchanged water Remaining amount.

Comparative Example 1 The recording ink of Example 1 containing no perfluoroalkyl polyoxyethylene ethanol.

Comparative Example 2 The recording ink of Example 2 containing no fluorinated alkyl ester.

Comparative Example 3 The recording ink of Example 3 containing no potassium perfluoroalkyl sulfonate.

Next, a method of evaluating the recording inks of the above-described examples and comparative examples will be described. Each recording ink was placed in a glass sample bottle, and in a sealed state, it was stored in a constant temperature bath at an ambient temperature of -20 ° C, 50 ° C, 70 ° C for 2 months,
The presence or absence of aggregates of pigment particles after storage and the presence or absence of precipitation of precipitates were examined, and those showing no change were judged as ◯.
The evaluation result is shown in FIG. As is clear from the figure, the recording inks of Examples 1 to 3 were used at all ambient temperatures of -20.
At 50 ° C, 50 ° C, 70 ° C, there is no pigment particle aggregate,
There was no precipitation and the storage stability was good.

The recording inks of Comparative Examples 1 to 3 are
There is a precipitate at an ambient temperature of -20 ° C, and an ambient temperature of 50
There were aggregates at 70 ° C and 70 ° C. As described above, the recording inks of Comparative Examples 1 to 3 have an ambient temperature of −20 ° C.
There is a change at 50 ° C and 70 ° C, and the storage stability is poor.

Although the storage stability test of this embodiment is not conducted at room temperature, the storage stability test at room temperature is for a long period of time, and therefore, as in this embodiment, the ambient temperature is 50 ° C. or 70 ° C. In this state, the same results as those obtained by conducting a long-term storage stability test at room temperature can be obtained in a short period of time. Such a test is generally known as an accelerated test and is well known. Further, such a test makes it possible to evaluate the long-term storage stability of the recording ink at room temperature and the storage stability at ambient temperatures of -20 ° C, 50 ° C, and 70 ° C.

The recording ink of this embodiment contains a substance having a fluorocarbon such as perfluoroalkylpolyoxyethylene ethanol, and polyvinylpyrrolidone in a state where perfluoroalkylpolyoxyethylene ethanol is dissolved in water. Since the pigment particles surrounded by the are dispersed, the polyvinylpyrrolidone is protected from hydration and the aggregation and precipitation of the pigment particles are prevented.

Printing was performed using the recording inks of Examples 1 to 3 described above in a shear mode type ink jet device disclosed in Japanese Patent Laid-Open No. 2-150355. As a result, good printing can be performed without nozzle clogging, the recording ink dries quickly after printing,
It was excellent in water resistance, abrasion resistance and finger touch.

Further, the recording ink of the above conditions is used in a Kaiser type ink jet device disclosed in Japanese Patent Publication No. 53-12138 and a thermal jet type ink jet device disclosed in Japanese Patent Publication No. 61-59914. The same effect was obtained as a result of printing.

[0038]

As is apparent from the above description, according to the recording ink of the present invention, the substance having the fluorocarbon is surrounded by polyvinylpyrrolidone in a state of being dissolved or dispersed in the water. As the pigment particles are dispersed, the polyvinylpyrrolidone is protected from hydration,
Aggregation and precipitation of pigment particles are prevented. Therefore, there is an effect that solidification and clogging of the recording ink can be prevented for a long period of time, and recording with high reliability and resolution can be achieved. Furthermore, the recording ink of the present invention has an effect that the high degree of weather resistance and water resistance of the pigment can be utilized to achieve the preservation of the record for a long period of time.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing evaluation of storage stability of Examples and Comparative Examples of the present invention.

Claims (3)

[Claims] 1. At least water and a pigment as a coloring material,
A recording ink containing polyvinylpyrrolidone, which is a water-soluble polymer, comprising a substance having fluorocarbon. 2. The recording ink according to claim 1, wherein the substance having fluorocarbon is a fluorochemical surfactant. 3. The recording ink according to claim 1, which is used in an ink ejecting device that ejects ink to print on a recording medium.