JPS5953563A - Jet ink composition - Google Patents

Abstract

PURPOSE:To provide a water-based jet ink composition usable for a long period without causing the clogging of the nozzle, and giving a record having excellent light resistance, by adding a water-soluble melamine to a jet ink composition. CONSTITUTION:A water-based jet ink composition composed mainly of a water- soluble dye, a wetting agent and water, is further added with preferably 0.1- 5wt% of one or more water-soluble melamines (e.g. hexamethoxy-methylmelamine) and if necessary, preferably 0.1-5wt% of a water-soluble quencher (preferably potassium iodide, potassium bromide, copper sulfate, cobalt sulfate or potassium thiocyanate).

Description

[Detailed description of the invention] The present invention relates to aqueous jet ink compositions.

More specifically, the present invention relates to an improved aqueous jet ink composition that can be used for a long time without clogging the nozzle of a jet printer, and can provide recorded matter with good light resistance.

By the way, the basic printing principles of known inkjet recording methods include electrostatic attraction type, intermittent ejection type using pulse pressure, and continuous ejection using continuous pressure of several atmospheres, from the viewpoint of the method of ejecting ink droplets from the nozzle. There are methods such as types. In addition, from the viewpoint of how to control ink droplets, there are charge deflection type, electric field deflection type, and non-charge type (on-demand type). In practice, it seems that various combinations of the above-mentioned ejection methods and ink droplet control methods have been proposed and implemented, each with its own unique features. However, depending on the method and the shape of the nozzle used, the physical properties of the ink (
The viscosity, surface tension, etc.) and electrical properties are different. Therefore, in any inkjet method, ink must be continuously and stably ejected as uniform ink particles from fine nozzles.

Therefore, the basic problem to be solved in inkjet printers is to completely prevent clogging of the nozzle portion and ensure continuous and stable generation of ink particles over a long period of time. Another important point is that stable ink particles can be created again after a temporary pause. Naturally, fine nozzles can become clogged even by the adhesion of even a small amount of solvent-insoluble solids. Furthermore, even if a solid object adheres to a part of the nozzle, the ink ejection direction changes.

Therefore, in order to eject ink particles continuously and stably, not only the viscosity and surface tension of the ink composition must be appropriate, but also the solvent-insoluble solid content in the ink composition must be completely removed. things are necessary. It is also necessary to completely prevent the generation of solvent-insoluble solids over time.

By the way, when coloring a water-based jet ink composition, by using a water-soluble dye, it is possible to achieve the following: removal or prevention of solvent-insoluble solid content.

However, in systems using water-soluble dyes, it is easier to meet the basic requirements of the inkjet method, such as preventing the generation of solvent-insoluble solids, but on the other hand, the light resistance of recorded materials is insufficient. There is a drawback that arises.

To explain this more specifically, after a certain period of time, recorded characters may disappear or become difficult to read, and especially in the case of color images, the image may change color due to differences in the light resistance of the mixed dyes. occurred often.

That is, the water-soluble dyes used in conventional water-based jet ink compositions have insufficient light resistance, cause nozzle clogging, and meet other conditions necessary for jet inks such as continuous jetting stability. In view of the types of colors, hues, etc. required for recorded materials, there were naturally limitations on the types that could be used.

Therefore, one of the inventors of the present invention first proposed an ink composition containing a water-soluble ultraviolet absorber in order to improve the various drawbacks and limiting conditions mentioned above. , (Special Public Interest Publication 56-1815
1) The requirements for light resistance in this type of market are becoming increasingly strict.

In addition, it is generally known that the light resistance of a dyed product (an inkjet recorded product in the present invention) is closely influenced (interacted) by various conditions such as the substrate, coexisting substances, and environmental conditions. Since sufficient research results have not yet been obtained regarding these problems related to photobleaching, it is difficult to assemble a unified theoretical system. For example, regarding substrates, well-known unique problems in interaction with substrates include the high light fastness of cationic dye dyed acrylic fibers and the low light fastness of nylon dyed yellow vat dyes. etc. are known. However, there is no knowledge of this kind regarding inkjet recorded matter.

In order to improve the light resistance of inkjet recorded materials, the present inventors investigated various water-soluble substances that improve light resistance by coexisting with dyes, and found that water-soluble melamine or water-soluble melamine and water-soluble quenching substances It has been found that the combination of canine IJ can improve the light fastness.

At the same time, the present inventors have developed an ink composition of the present invention, that is, an aqueous jet ink, which does not generate solvent-insoluble solids that cause nozzle clogging in an inkjet system, and which does not impair the recording characteristics of inkjet recording. Thus, a novel ink composition has been achieved, which is a combination of a water-soluble melamine composition, a water-soluble melamine resin, or a water-soluble quenching substance.

Therefore, it is an object of the present invention to further improve the light resistance of recorded materials, and to provide a water-based jet ink composition that can be used in an aqueous jet ink composition that is free from nozzle clogging, which has conventionally been unavoidable in inkjet systems. An object of the present invention is to provide a new water-based jet ink composition that is intended to expand the types of water-soluble dyes that can be used.

That is, the present invention provides: (1) an aqueous jet ink composition containing a water-soluble dye, a wetting agent, and water as main components, further comprising at least one kind of water-soluble melamine; (2) A water-based jet ink composition containing a water-soluble dye, a wetting agent, and water as main components, further comprising at least one water-soluble melamine and at least one water-soluble quenching substance.

The water-soluble melamine used in the present invention is, for example, a water-soluble one such as hexamethoxymethylmelamine or hexamethoxymethylolmelamine, and is generally easily available on the market.

The water-soluble melamine is preferably contained in an ink composition containing a water-soluble dye, a wetting agent, and water as main components in an amount of 0.1 to 5% by weight. Naturally, if the amount of water-soluble melamine used is too small, the effect of improving light resistance cannot be obtained. On the other hand, if the amount is too high, there is a tendency for the color rendering properties to deteriorate and the nozzle to be clogged with precipitates.

Further, as the water-soluble dye used in the aqueous jet ink composition of the present invention, any dye having good solubility in water can be used. However, the effect of the present invention is that a strong additive effect can be achieved even in dyes with weak light resistance.

Examples of the water-soluble dye include C.1. Direc
tBlue 236, C, I, DirectBl
ue 203, C, I.

Direct 81ue202, C, 1, Dire
ct Blue 15.

C,1,Ac1d Blue 7, C,1,Ac
1d Blue 9, C, l.

Direct Blue 199, C, 1, Ac1
d Yellow 1.

C,1,Direct Red 227, C,1,
Direct Red 225.

C,1,Ac1d Recl 87, C,1,Ac
1d Red 92, C,I.

Ac1d Red 52, C,1, Ac1d R
ed94. , C,1,Ac1dRed 289 ,
C, In Direct Black 51, etc.

′! 1'/In the present invention, a wetting agent that is liquid at room temperature is used. Specific examples of the wetting agent include polyhydric alcohols such as diethylene glycol, triethylene glycol,
+mw Glycerin, propylene glycol, etc., alkyl ethers of polyhydric alcohols and their acetate esters, such as ethylene glycol monomethyl ether, diethylene glycol, monobutyl needle, ethylene glycol monomethyl ether acetate, trifluoropylene glycol methyl ether, etc.; hydroxyalkyl Formamides, for example, where the alkyl group has 1 to 4 carbon atoms
Hydroxyalkylformamides in the range of -1; and 11-1:% N-vinyl-2-pyrrolidone oligomers synthesized by the method described in Japanese Patent Publication No. 102407/1983, etc. are used.

These humectants can be used alone or in combination.

On the other hand, another aspect of the present invention includes an aqueous jet ink composition further containing a water-soluble quencher.

In this embodiment, the above-mentioned quenching substance, that is, a substance that deactivates the fluorescence of the excited substance by interaction [Kyoritsu Shuppan Co., Ltd., Chemistry Encyclopedia No. 4].

[Page 769] is preferably potassium iodide, potassium bromide, potassium chloride, potassium thiocyanate,
At least one compound selected from cobalt sulfate, copper sulfate, ferrous sulfate, nickel sulfate and nickel oxalate is used. Among these, it is particularly preferable to use at least one of potassium iodide, potassium bromide, copper sulfate, MH cobalt, and potassium thionate.

The quenching substance is preferably present in an ink composition consisting of a water-soluble dye, a wetting agent, a water-soluble melamine, and water.
It is contained in a range of ft% by weight. Naturally, if the amount of water-soluble quenching substance used is too small, the effect of improving light resistance cannot be obtained. On the other hand, if the amount is too large, the color rendering properties tend to deteriorate and the nozzle is clogged with precipitates, which is similarly undesirable.

The aqueous Noette ink composition of the present invention has the following formulation, for example. Water-soluble dye 0.1-15% by weight, wetting agent 5-40% by weight, water-soluble melamine 0.1-5% by weight, water-soluble quenching substance 0.1-5% by weight if necessary.
, remaining water.

The aqueous jet ink composition of the present invention as described above includes:
From a practical point of view used in inkjet method, the viscosity is 1.2 to 60 cm7''? The size and nonvolatile content are preferably in the range of about 50% by weight or less. Furthermore, although the pH of the ink can vary widely, it is preferable to adjust it appropriately depending on the type of quenching substance and the pH (sometimes precipitation may occur). For example, sulfuric acid steel has a pH of 4.
It is preferable to adjust the pH to 10.5 or more with an ammonia solution.

The aqueous jet ink composition of the present invention may further include a water-soluble solvent, such as dioxane, acetone, diacetone alcohol, alkyl alcohol having 1 to 2 carbon atoms, trimethylformamide, and nomethylsulfonate. One or two of oxide, N-methyl-2-pyrrolidone, etc.
More than one species may be used.

If necessary, as surface tension adjusting agents, cationic surfactants such as sodium alkyl sulfates; anionic surfactants such as alkyl pyridylam sulfates; nonionic surfactants? 'i11, for example, I
P-lyoxyethylene alkyl ether, etc.; or amphoteric activators may also be used.

Furthermore, if necessary, hydroxypropyl cellulose,
carboxin methylcellulose, hydroxyethylcellulose, millivinyl alcohol, etc.) Viscosity modifier; sodium dehydroacetate, 1,2-benzisothiazoline-3-
Amine salt of 6-acetoxy-2,4-methyl-
A small amount of a fungicide such as m-dioxane or a preservative may also be added. Further, oxygen absorbers such as sodium sulfite and sodium hydrogen sulfite can also be used together.

Aqueous jet ink composition 1 of the present invention thus obtained
/i: Completely satisfies the requirements and performance of the ink jet system, such as preventing nozzle clogging. Moreover, one of the records
iii) It can significantly impair photoresistivity. In addition, it is possible to expand the so-called range of selection by using various water-soluble dyes.

As a result of the above, its industrial effects are immeasurable.

Hereinafter, the present invention will be specifically explained with reference to Examples.

However, it is not intended to be limited to these specific examples.Examples 1 to 8 The ink raw materials shown in Table 1 were mixed with stirring for 0.5 hours or more, and each raw material was dissolved in water. Ta. Then, the mixture was filtered under pressure using a 1.2 μm Millipore (I) 0 membrane filter to obtain an aqueous jet ink composition.

These aqueous jet ink compositions were continuously recorded using an on-demand inkjet printer, and the continuous jetting stability was determined based on the recording state after 100 hours and the printing quality of the recorded matter.

Regarding rigidity, after irradiating the recorded material with a xenon fade meter (manufactured by Suga Test Instruments Co., Ltd.) for a predetermined period of time (irradiation energy: 464.joules/Crn-hr),
Using a reflection densitometer (RD915 manufactured by Macbeth), the degree of color fading was compared based on the ratio of optical density to the initial value (100). The results obtained are shown in Table 1.

Comparative Examples 1 to 4 Water-based Noet ink compositions were prepared from the compositions shown in Table 1, which were conventionally thought to have good light resistance, in the same manner as in the above Examples. The resulting composition was tested for continuous jet stability and light resistance in the same manner as in the Examples.

As is clear from the results in Table 1 above, the Noenoto ink composition of the present invention has good continuous jetting stability without any loss in jetting properties even in inkjet systems, and has excellent stability on the surface of recorded materials. j It also has excellent optical properties.

Patent applicant: Dainippon Toyo Co., Ltd. 526-

Claims (6)

[Claims] (1) An aqueous jet ink composition containing a water-soluble dye, a wetting agent, and water as main components, further comprising at least one kind of water-soluble melamine. (2) The water-soluble melamine is contained in the jet ink composition in an amount of 0.1 to 5% by weight.
) The jet ink composition described in item 1. (3) A water-based jet ink composition containing a water-soluble dye, a wetting agent, and water as main components, further comprising at least one water-soluble melamine and at least one water-soluble quenching substance. Ink composition. (4) The water-soluble melamine is contained in the jet ink composition in an amount of 0.1 to 5% by weight.
) The jet ink composition described in item 1. (5) The water-soluble quenching substance is contained in the jet ink composition in an amount of 0.1 to 5% by weight.
) The jet ink composition described in item 1. (6) The water-soluble quenching substance is at least one selected from potassium iodide, potassium bromide, potassium chloride, potassium thiocyanate, cobalt sulfate, copper sulfate, ferrous sulfate, nickel sulfate, and nickel oxalate. A jet ink composition according to certain claim (3).