Ink Composition

The present invention relates to ink compositions, more particularly to an ink composition especially suitable for a marking pen.

Presently, inks prepared by dissolving an oil-soluble dye and resin in xylene are mainly employed for marking pens which are extensively used at home, school, office, etc. as writing and drawing implements. However, xylene has the objections of: (1) giving off a vapor having a strong odor to intensely stimulate the eyes, nose and throat, (2) causing troubles in the marrow when inhaled over a prolonged period of time even in a very small amount, and (3) producing dermatitis when xylene contacts the skin repeatedly. For this reason, it has been desired to provide an ink for marking pens (hereinafter referred to briefly as "ink" unless otherwise specified) prepared by using a solvent of weak odor and low toxicity. In fact, inks have recently become available which are prepared by dissolving an oil- or alcohol-soluble dye and resin in methyl cellosolve of a low odor. Although methyl cellosolve is weak in odor, it is as toxic as xylene and involves the hazard that the vapor of the ink will be inhaled by the user or the ink will contact his skin. Thus the ink proposed has not overcome the objections heretofore experienced. Furthermore, when a drawing or writing is made on paper or the like with the conventional ink, the dye continues to sublime from the ink-deposited portion even after the ink has been dried, with the result that the color transfers to paper, cloth or the like which comes into contact with the inked portion, which in turn undergoes fading.

It is known that an aliphatic hydrocarbon solvent is weak in odor and much lower than xylene or cellosolve in toxicity to the human body, but the use of this solvent is infeasible inasmuch as at present there is no dye available that is soluble therein to a concentration required for the ink. Indeed, when the solvent is used for the known dyes, low dye concentrations will inevitably result to give light colors.

Accordingly, a main object of this invention is to provide a dye which is readily soluble in a substantially odorless and nontoxic aliphatic hydrocarbon solvent to a high concentration.

Another object of this invention is to provide a dye which will not sublime from the ink-deposited portion after it has been dried.

Another object of this invention is to provide an ink which is low in odor and toxicity such that it will not adversely affect the human body even when used over a long period of time.

Still another object of this invention is to provide an ink having a high concentration of dye and excellent in tinctorial properties.

Other objects and features of this invention will become more apparent from the following description.

The present invention provides an ink composition which comprises an aliphatic hydrocarbon solvent having dissolved therein a resinous binder and a dye, said dye being a modified dye obtained by reacting (a) a dye having at least one group of --CO.sub.2 M and --SO.sub.3 M in the molecule wherein M is an alkali metal with (b) an organic ammonium compound represented by the formula ##EQU1## wherein R.sub.1, R.sub.2 R.sub.3, R.sub.4 and R.sub.5 are respectively a hydrocarbon radical having 1 to 40 carbon atoms, a radical of a hydrocarbon bonded to a hydrocarbon by a divalent group of --O--, --S--, --COO--, --CONH-- or --NH--, the total carbon number of both hydrocarbons bonded being in the range of 2 to 40, or ##EQU2## R' being an alkyl having 1 to 15 carbon atoms or an alkenyl having 1 to 20 carbon atoms, provided that the total carbon number of R.sub.1 R.sub.2 R.sub.3 and R.sub.4 is in the range of 11 to 55: R.sub.6, R.sub.7 and R.sub.8 are respectively a hydrogen atom, a hydrocarbon radical having 1 to 40 carbon atoms, a radical of a hydrocarbon bonded to a hydrocarbon by a divalent group of --O--, --S--, --COO--, --CONH-- or --NH--, the total carbon number of both hydrocarbons bonded being in the range of 2 to 40, or ##EQU3## R' being an alkyl having 1 to 15 carbon atoms or an alkenyl having 1 to 20 carbon atoms, provided that all of R.sub.6, R.sub.7 and R.sub.8 are not hydrogen atom and the total carbon number of R.sub.6, R.sub.7 and R.sub.8 is in the range of 8 to 40: X is a halogen atom and A is an acid residue. According to the researches of the present inventor it has been found that a modified dye obtained by reacting a dye having at least one of CO.sub.2 M groups and SO.sub.3 M groups with an organic ammonium compound represented by the formula (I), (II) or (III) dissolves in an aliphatic hydrocarbon solvent to a very high concentration, making it possible to obtain an ink of deep color without using xylene, cellosolve or like solvent which is detrimental to the human body. The reason why the reaction product described above is highly soluble in an aliphatic hydrocarbon solvent has not been fully clarified yet.

Further this invention assures greatly reduced sublimation of dye from the inked portion after the ink has been dried, consequently eliminating the transfer of color to paper, cloth or the like which will contact the inked portion and permitting hardly any fading of color in the inked portion over a long period of time.

The dyes to be used according to this invention are those having at least one of --CO.sub.2 M groups and --SO.sub.3 M groups wherein M is as defined above and include various dyes such as monoazo dyes, disazo dyes, trisazo dyes, polyazo dyes, anthraquinone dyes, triphenylmethane dyes, xanthen dyes, stilbene dyes and indigo dyes. These dyes are used singly or in combination with one another.

Examples of dyes to be used in this invention are shown below, all of which are indicated in accordance with Colour Index (2nd ed.) edited by The American Association of Textile Chemist and Colorists, U.S.A. and The Society of Dyers and Colourists, Great Britain:

1. Monoazo dyes:

Direct Yellow 8, 27, 28,

Acid Yellow 11, 17, 23, 25, 29, 36, 40, 76, 98, 99,

Direct Red 20,

Acid Red 1, 6, 8, 9, 13, 14, 18, 26, 27, 32, 35, 37, 42, 133, 155, 180, 183, 184, 186, 198, 249, 265,

Acid Blue 92, 117, 158, 161,

Direct Orange 39, 41,

Acid Orange 1, 7, 8, 10, 19, 20, 28, 41, 78,

Acid Violet 7, 11,

Acid Green 12, 35,

Acid Brown 2, 4, 20

Acid Black 51, 52, 107.

2. Disazo dyes:

Direct Yellow 1, 12, 24, 33, 44,

Acid Yellow 38, 42, 44,

Direct Red 1, 2, 4, 13, 17, 23, 24, 28, 31, 33, 37, 39, 44, 46, 62, 63, 75, 79, 81, 83, 229,

Acid Red 85, 89, 97, 111, 114, 115, 134, 145, 154, 158, No. 26670,

Direct Blue 1, 2, 6, 15, 22, 25, 76, 90, 98, 158, 165, 168, 226,

Acid Blue 29, 113, 120, 123,

Direct Black 17, 51,

Acid Orange 24, 33, 45, 51, 56

Direct Violet 1, 7, 9, 12, 22, 35, 48, 51, 63,

Acid Green 19, 20,

Acid Brown 14,

Direct Orange 1, 6, 8, 10, 26, 29, 49, 102,

Direct Brown 2, 58, 59,

Acid Black 1, 7, 24, 26, No. 20510.

3. Trisazo dyes:

Direct Blue 71, 78, 120, 163,

Direct Green 1, 6, 8, 33, 59,

Direct Brown 1A, 6, 27, 95, 101, 173,

Acid Black 94.

Polyazo dyes:

Direct Yellow 60,

Direct Red 32, 80, 84, 194,

Direct Blue 131, 150, 159, 162, 175, 176,

Direct Brown 13, 14, 31, 33, 39, 43, 44, 63, 70, 73, 74, 100, 127, 149, 150, 215,

Acid Brown 25, 92, 106, 119, 120, 123,

Direct Black 19, 22, 28, 32, 34, 75, 76, 77, 97, 100, 112.

5. Anthraquinone dyes:

Acid Red 80, 82, 83,

Acid Blue 23, 25, 27, 40, 41, 43, 45, 67, 78, 80, 138,

Acid Violet 34, 41, 43, 51, No. 62000,

Acid Green 25, 27, 36, 41, 44,

Acid Brown 27,

Acid Black 48.

6. Triphenylmethane dyes:

Acid Blue 1, 7, 9, 15, 22, 83, 90, 93, 100, 103, 104,

Direct Blue 41,

Acid Violet 15, 49,

Acid Green 3, 9, 16.

7. Xanthene dyes:

Acid Yellow 73, 74,

Acid Red 51, 52, 87, 91, 92, 93, 94, 95, 98,

Acid Blue 19

Acid Violet 9.

8. Stilbene dyes:

Direct Yellow 11, 39.

9. Indigo dyes:

Acid Blue 74.

Among these dyes, preferable are those having one to two --CO.sub.2 M groups, one to two --SO.sub.3 M groups or both --CO.sub.2 M group and --SO.sub.3 M group wherein M is sodium.

The organic ammonium compounds to be reacted with the dyes according to this invention are represented by the formulas (I), (II) and (III) and used singly or in combination with one another. Insofar as the definitions with respect to the carbon number are fulfilled, the hydrocarbon radicals represented by the R.sub.1 to R.sub.8 may be either a saturated or unsaturated cyclic hydrocarbon radical or saturated or unsaturated chain hydrocarbon radical respectively having or not having substituents. Typical of the organic ammonium compounds to be used in this invention are shown in Tables 1 - 3 below:

I. Examples of quaternary ammonium halides represented by the formula (I) are shown in Table 1:

II. Examples of pyridinium halides represented by the formula (II) are shown in Table 2 below:

III. Examples of organic and inorganic acid salts of primary, secondary and tertiary amines represnted by the formula (III) are acid salts such as hydrochlorides, formates, acetates, lactates etc., which are shown in Table 3 below:

Among these typical organic ammonium compounds, particularly advantageous are: (a) quaternary ammonium chlorides represented by the formula (I) above, (b) pyridinium chlorides represented by the formula (II) above and (c) primary, secondary and tertiary amine hydrochlorides represented by the formula (III) above.

The modified dye of the present invention can be prepared by the reaction of a dye having at least one of CO.sub.2 M groups and SO.sub.3 M groups with an organic ammonium compound represented by the formula (I), (II) or (III). The reaction can be conducted in water or organic solvent with stirring at a temperature from about 20.degree. to about 70.degree.C, preferably of about 40.degree. to 50.degree.C. The resultant reaction mixture is washed with water to separate the modified dye, followed by drying. The organic ammonium compound represented by the formula (I), (II) or (III) is used in an amount of at least one mole per mole of the dye. When the dye contains two or more substituents represented by --COOM and/or SO.sub.3 M, the organic ammonium compound can be employed in such an amount that at least one of the above substituents contained in the dye molecule is reacted with the organic ammonium compound. Examples of the organic solvents used in the reaction to prepare the modified dye are alcohols, ketones, ethers, esters, aromatic solvents, aliphatic hydrocarbons, alcyclic hydrocarbons, etc., among which preferable are alcohols, ketones and ethers. The above reaction of dye with organic ammonium compound can be conducted prior to or simultaneously with the preparation of the present ink composition. In the latter case it is preferable to first dissolve a resinous binder in aliphatic hydrocarbon serving as a solvent for the ink composition and thereafter to add the dye and organic ammonium compound thereto for the reaction conducted in the same manner as above.

The resultant modified dye has a structure in which at least one of --COOM and/or SO.sub.3 M contained in the molecule is reacted with one mole of the organic ammonium compound, is insoluble in water but soluble in an aliphatic hydrocarbon, and has the same colour as the original dye.

The aliphatic hydrocarbon solvents to be used in this invention which may differ with the type of the dye used, the desired concentration of ink, etc. are preferably those boiling at about 75.degree. to 180.degree.C from the viewpoint of preservability of ink over a prolonged period of time and drying speed after drawing or writing. Such solvents can be used alone or in admixture with one another and typical examples thereof are:

I. hydrocarbons of methane series: heptane, octane, nonane, decane and like normal paraffins, isooctane and like isoparaffins,

Ii. hydrocarbons of ethylene series: 1-heptene, 1-octene, 1-nonene, etc.

Iii. ligroin, petroleum spirit, refined gasoline and like aliphatic hydrocarbon solvent mixtures.

The resinuous binder to be used in the invention, which assures satisfacory adhesion of the ink on the drawing or writing surface, includes various natural or synthetic resins heretofore used in marking pen inks. Typical of resinous binders are:

1. Rosin derivatives: pentaerythritol-rosin ester, pentaerythritolhydrogenated rosin ester, ester gum, hydrogenated resin, maleinized rosin, etc.

2. Petroleum resins: coumarone-indene resin, polyolefin, etc.

3. alkyd resins: alkyd resins modified with drying oil or rosin, phenolated alkyd resin, styrenated alkyd resin, etc.

Among these resins, preferable are pentaerythritolrosin ester, pentaerythritol-hydrogenated rosin ester, ester gum, hydrogenated rosin, maleinized rosin and polyolefin.

The concentration of the modified dye and resinuous binder in the present ink composition varies widely with the kind of modified dye and aliphatic hydrocarbon solvent used, etc. Usually, the concentration of modified dye is in the range of 5 to 20%, preferably 5 to 15% by weight and that of resinuous binder is in the range of 5 to 35 %, preferably 10 to 20% by weight, based on the total weight of the ink composition.

The ink composition of this invention is prepared by adding the modified dye previously prepared as above to an aliphatic hydrocarbon solvent along with the resinuous binder and stirring the mixture at a temperature from about 20.degree. to about 70.degree.C to completely dissolve the modified dye and the resinous binder in the solvent. Alternatively, the ink composition of this invention is prepared by adding a dye, organic ammonium compound and resinuous binder to an aliphatic hydrocarbon solvent at the same time or in suitable sequence and stirring the mixture at a temperature from about 20.degree. to 70.degree.C to produce modified dye completely dissolved in the solvent along with the resinuous binder. In the latter case, it is preferable to prepare the ink composition by dissolving the resinuous binder, the organic ammonium compound and the dye in sequence in order to increase the solubility of the modified dye to the aliphatic hydrocarbon solvent. To the ink composition of the present invention can be added further one or more dyes in order to change the colour tone.

To clarify the features of this invention, examples are given below in which parts are all by weight.

Predetermined amounts of dyes and quaternary ammonium chlorides (I) shown in Table 4 below were respectively added to 130 parts of water, and the mixtures were stirred at 40.degree. to 50.degree.C for about 20 minutes and the resultant precipitates in the mixture were filtered off. After repeatedly washed with water and dried, the precipitates were subjected to extraction with 100 parts of toluene. When the toluene was evaporated off under a reduced pressure, purified modified dyes were obtained as shown in Table 4 below, all of which were insoluble in water and soluble in aliphatic hydrocarbon solvent and had the same colour as the original dyes.

Then predetermined amounts of the modified dyes obtained as above and pentaerythritol-resin ester ("Pentaester", trademark, product of Tokushima Seiyu Co., Ltd., Japan) were added to predetermined amounts of refined gasoline ("Rubbersol", trademark, product of Kyodo Petroleum Co., Ltd., Japan) to obtain the ink compositions as shown in Table 5 below.

Every ink composition obtained as above tinctured a drawing surface satisfactorily in a deep color, was weak in odor, produced hardly any stimulation on the skin, and no color transfer was found on paper which was held in intimate contact with the drawing surface for a long period of over one month.

Predetermined amounts of dyes and quaternary ammonium chlorides [formula (I)] shown in Table 6 below were respectively added to 130 parts of ethanol, and the mixtures were stirred at 40.degree. to 50.degree.C for about 20 minutes. 300 parts of cold water was then slowly added to the mixtures, and the resultant precipitates were filtered off, followed by the same procedure as in Example 1 to obtain purified modified dye shown in Table 6 below, all of which were insoluble in water and soluble in aliphatic hydrocarbon solvent and had the same colour as the original dyes.

Then predetermined amounts of modified dyes obtained as above and resinuous binders were dissolved in predetermined amounts of solvents to obtain the ink compositions shown in Table 7 below.

Every ink composition obtained as above had distinguished properties the same as the compositions obtained in Example 1.

From dyes and pyridinium chlorides as shown in Table 8 below modified dyes were obtained by the similar procedure as in Example 2 except that ethyl cellosolve was used instead of ethanol. All of the modified dyes thus obtained were soluble in aliphatic hydrocarbon solvent and insoluble in water and had the same colours as the original dyes.

Ink compositions were prepared by dissolving the modified dyes obtained as in Table 8 above and resinuous binders in solvents as shown in Table 9 below.

Modified dyes were obtained from dyes and acid salts of amines [formula (III)] as shown in Table 10 below by the similar procedure as in Example 2 except that methyl ethyl ketone was used instead of ethanol. All of the modified dyes thus obtained were soluble in aliphatic hydrocarbon solvent and insoluble water and had the same colours as the original dyes.

Ink compositions shown in Table 11 below were prepared by the same procedure as in Example 3.

To aliphatic hydrocarbon solvents kept at a temperature of about 70.degree.C were added resinous binders with stirring, and further organic ammonium compounds to be reacted with dyes were added slowly with stirring to effect complete solution. Subsequently, dyes were added slowly to the resulting solutions, followed by stirring for 11/2 hours and then by cooling to room temperature. The filtration of insoluble precipitates gave ink compositions of the present invention as shown in Table 12 below.