GB2115830A - Dual color ink composition - Google Patents

Abstract

A dual color ink composition comprises a solvent, a binder resin soluble in the solvent and coloring agents. The coloring agents comprise a first pigment of a first color not less than 0.5 microns in the maximum frequency particle size in particle size distribution, and a dyestuff of a second color soluble in the solvent or a second pigment of a second color smaller than the first pigment and not larger than 1 micron in the maximum frequency particle size. The ink composition writes on an absorbent or pervious writing surface to form the inner portions of a first color with the outer contour line therearound of a second color enclosing therein the inner portions of the marking.

Description

SPECIFICATION Dual color ink composition The present invention provides a dual color ink composition, and more particularly, an ink composition which when applied to a pervious or absorbent writing surface provides marking or writing composed of an inner portion of a first color enclosed within a contour line of another color.

The ink composition according to the invention comprises 2080% by weight of a solvent, 0 to 30% by weight of a binder resin soluble in the solvent, and at least two coloring agents dissolved or dispersed in the solvent, the coloring agents comprising: (a) 360% by weight of a pigment of a first color having a number average particle size not less than 0.5 microns, and (b) 0.120% by weight of a dyestuff soluble in the solvent of a second color or of a second pigment of a second color and of particle size smaller than that of the first pigment and having a number average particle size not larger than 1 micron.

The first pigment used in the ink composition of the invention has a particle size large enough to be trapped in the fibrous network of a pervious or absorbent surface such as paper or cloth when the ink composition is applied thereonto. In other words, the first pigment is such that it does not substantially permeate through the fibrous network of the pervious writing surface but remains thereon when the ink composition is applied thereonto and the solvent therejn has permeated through and diffused into the fibrous network.The first pigment therefore preferably has a particle size of at least 0.5 microns as the maximum frequency particle size in particle size distribution, although the actual value somewhat depends on the chemical and physical properties of the fibrous network, the ingredients and viscosity of ink composition and the surface properties and density of the pigment used therein, etc. More preferably, the first pigment has an average particle size of not less than 2 microns so that it is readily trapped on most absorbent writing surfaces.

A metal powder pigment is most preferably used as the first pigment, and some examples thereof are aluminum powder pigment, bronze powder pigment and copper powder pigment.

So-called metal powder pastes commercially available and comprising metal powder dispersed in a solvent are advantageously used in the invention because of their easy handling. Colored metal powders such as colored aluminum powder may also be used. Inorganic pigments such as carbon black, cobalt green, cobalt blue, yellow ochre, red iron oxide, viridian, cadmium yellow and ultramarine blue, and organic pigments such as Ha nsa Yellow may also be used as the first pigment. The ink composition of the invention includes the first pigment in amounts of 360% by weight, preferably 1040% by weight based on the ink composition.

As second coloring agent the ink composition of the invention may include a dyestuff soluble in the ink solvent used and different in color from the first pigment so as to permeate through the fibrous network of the pervious surface together with the solvent to form the outer portions or contour lines of different color which enclose the inner portions of the marking. Any dyestuff may be used which is suitable for incorporation into ink compositions. For water-based ink compositions, the dyestuff may be a basic, an acid -or a direct dyestuff, and for solvent-based ink compositions, various oil-soluble dyestuff may be used depending upon the solvent used. In the invention, a dyestuff need not be actually soluble in the solvent provided that the dyestuff when finely divided and dispersed in the solvent used will permeate through the fibrous network of the writing surface.

According to the invention, a second pigment may be used in place of or together with the dyestuff as the second coloring agent to form the enclosing contour line of the marking or writing.

The second pigment must, like the dyestuffs that can be used, be of particle size small enough to permeate through and diffuse into an absorbent writing surface together with the solvent used, when writing, and therefore the second pigment has a particle size smaller than that of the first pigment. The second pigment preferably has an average particle size not larger than 1 micron.

It is not desirable to use a pigment of particle size larger than 1 micron as the second pigment since such a pigment tends to be trapped and fixed on the surface of a permeable writing surface. As the second pigment there may be used for example, carbon black, Phthalocyanine Blue and various lakes. The ink composition of the invention includes the dyestuff and/or the second pigment in amounts of 0.1-20% by weight, preferably 0.5-1 5% by weight based on the total ink composition.

It should be understood, however, that the first and the second pigments are relatively distinguished from each other only in particle size and color and hence a pigment may be used as the first pigment in some ink compositions and as the second pigment in other ink compositions depending upon the particle size of a second pigment used.

Any solvent may be used as a vehicle for the ink composition of the invention depending upon whether the ink is to be water-based or solventbased. In a water-based composition, water or a mixture of water and a water-soluble organic solvent is used. As a water-soluble organic solvent there may be used, for example, a C1-C8 monohydric or polyhydric alcohol such as ethanol, propanol, glycerine, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol or ethylene-glycol monoalkylether, or a C3-C10 aliphatic or alicyclic ketone such as methyl ethyl ketone or cyclohexanone.The incorporation of a lower aliphatic alcohol such as ethanol, propanol or ethyleneglycol monoethylether and/or a ketone such as methyl ethyl ketone is preferred to enhance the permeability of the ink composition into the absorbent fibrous network. On the other hand, a polyhydric alcohol such as glycerine or ethylene glycol serves to depress the evaporation and loss of volatile components in the ink composition. A water-based ink composition may further contain urea or thiourea to achieve smoother writing therewith since urea or thiourea depresses very effectively the evaporation of water and other volatile components in cooperation with a polyhydric alcohol.A waterbased ink composition preferably further contains effective amounts of surfactant so that the pigments are more uniformly dispersed therein and so that the ink composition has a higher permeability into the fibrous network when writing. Any surfactant may be used, for example, a polyoxyethylenealkylether, a sorbitan fatty acid ester or an alkylamine.

In a solvent-based ink composition, as organic solvent there may be used, for example, a C6-C10 alicyclic hydrocarbon such as cyclohexane, methylcyclohexane, ethylcyclohexane or dimethylcyclohexane, a C5-C12 aliphatic hydrocarbon such as n-hexane or n-octane, a C6-C10 aromatic hydrocarbon suchsas benzene, toluene or xylene, a C3-010 aliphatic or alicyclic ketone such as methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, a C3-C10 aliphatic carboxylic acid alkyl ester such as ethyl acetate, butyl acetate, butyl propionate or amyl acetate, or a C1-C6 aliphatic alcohol such as ethanol, propanol, butanol or ethyleneglycol monoethyl- or monobutyl ether, or a mixture of any two or more such solvents.

The ink composition of the invention, waterbased or solvent-based, contains the solvent as aforesaid in amounts of 2080% by weight, preferably 3570% by weight based on the ink composition. The specified amounts of coloring agents and solvent can impart a proper viscosity for writing to the ink composition.

The ink composition of the invention preferably contains a binder resin in an amount not more than 30% by weight based on the ink composition, preferably 120% by weight, so that the ink has a proper adhesiveness onto a writing surface as well as a proper viscosity. Any resin may be used as a binder depending upon the solvent used. A water-soluble resin is used in a water-based ink composition, and sodium carboxymethylcellulose, polyvinyl alcohol and polyvinyl pyrrolidone, for example are preferably used in such inks according to the invention. In a solvent-based ink composition, on the other hand, a resin soluble in the solvent used is incorporated into the ink composition.There may be used, for example, natural resins such as rosin, a rosin modified resin, such as a rosin ester, a rosin modified maleic acid resin or a rosin modified phenol resin, a phenolic resin, a petroleum resin, a ketone resin, an alkyd resin, a xylene resin, an indene-coumarone resin, a cellulose resin or ethylcellulose or acetylcellulose, polyvinyl butyral resin, a vinyl chloride-vinyl acetate copolymer, a vinylidene chloride-acrylonitrile copolymer, a vinylidene chloride-vinyl chloride copolymer or a mixture of any two or more such resins.

When necessary, the ink composition of the invention may further contain an effective amount of additional additives such as an antiseptic, e.g.

sodium benzoate and potassium sorbate, or a plasticizer, e.g. dioctyl phthalate and tricresyl phosphate. A rust-preventive agent may also be contained in the ink composition, if necessary, in particular in compositions which contain a metal powder pigment as the first pigment therein.

When marking or writing is formed on an absorbent or pervious surface such as paper or cloth with the ink composition of the invention, the first pigment comprising coarse particles is trapped and fixed on the pervious surface along the marking to form the inner portions of marking.

The dyestuff and/or the second pigment comprising finer particles also in part form the inner portions of the marking together with the first pigment, but also in part permeate into and through the writing surface together with the solvent to reach the outside of the margin of the marking or writing, thereby to form the outer portions or contour line of the marking so as to enclose the inner portions therein. That is, dual color marking is formed which comprises the inner portions of one color enclosed within a contour line of the other color.

The inner portions of marking or writing are formed by the first pigment and occasionally in part by the dyestuff and/or the second pigment, and hence comprises a single or mixed color based thereon, whereas the outer portions are formed by the dyestuff and/or the second pigment, as described above. Therefore, when a pigment is used for forming the outer contour of marking, the larger the difference in the particle size between the first and second pigments used or the larger the hiding and/or tinting power of the first pigment, then the more clearly are the inner portions of the marking colored by the first pigment. However, when the difference in the particle size between the first and the second pigments is small or when the first pigment has small hiding and/or tinting power while the second pigment has large hiding and tinting power, then the inner portions of the marking may have a color based on a mixture of the two pigments or first pigment and dye. The width of the contour line may be varied by controlling the permeability of solvent used, and by suitably choosing the particle size of a second pigment when one is used in the composition.

The ink composition of the invention is applied onto a pervious writing surface preferably with a so-called felt-tip marking pen such as to provide marking about 1-50 mm in width. The ink composition may however be used with any desired writing tool.

The ink composition of the invention may be prepared by any known method in the art. For example, a binder resin, and when necessary, a surfactant, an antiseptic and a plasticizer, are added to a solvent and stirred, and then to the resultant solution is added the dyestuff and/or the second pigment, and this mixture is stirred for a sufficient period of time under heating if necessary. Then the first pigment is added to the resultant dispersion and stirred for a period of time sufficient to provide a uniform ink composition. Alternatively, all the ingredients may be added to a solvent at the same time. Any dispersing means such as a ball mill may be used in the preparation of the ink composition if necessary.

The present invention will be more clearly understood with reference to the following examples, which however are intended to iliustrate the invention only and are not to be construed to limit the scope of the invention. In the examples, sunless otherwise stated, quantities are expressed as parts by weight and particle size of pigment used means the maximum frequency particle size.

Example 1 The following ingredients were mixed and stirred for 1 hour at room temperature: 2 parts of C.l. Acid Red 92 (Hodogaya Chemical Co., Ltd., Aizen Acid Phloxine PB) 2 parts of sodium carboxymethylcellulose (Daiichi Kogyo Seiyaku Co., Ltd., Cellogen 6A) 20 parts of ethyleneglycol 2 parts of ethyleneglycolmonobutylether 0.2 parts of surfactant (polyoxyethyleneoleylether, Daiichi Kogyo Seiyaku Co., Ltd., Noigen P) 1 part of sodium benzoate 0.2 parts of rust-preventive agent (Kao-Atlas Co., Ltd., Corromin CB) 43.8 parts of water.

To the resultant mixture 30 parts of bronze powder pigment (Toyo Aluminum Co., Ltd., BS 947) was added and the mixture was stirred for another 1 hour at room temperature to provide an ink composition, which when applied to paper forms markings composed of an inner golden portion enclosed within an outer red contour line.

Example 2 The following ink composition was formulated in the same manner as in Example 1: 1 part of Cyanine Blue (Dainichi Seika Color s Chemicals Mfg. Co., Ltd., #4920) 6 parts of glycerine 1 5 parts of ethyleneglycol 0.2 parts of surfactant (Kao-Atlas Co., Ltd., Scourol #400) 1 part of sodium benzoate 0.2 parts of rust-preventive agent (Tatsuta Electric Wire Co., Ltd., Pal C) 1 5 parts of water dispersion aluminum powder paste (Toyo Aluminum Co., Ltd., Alpaste 1 SOOMA, solid content 70%) 61.6 parts of water.

The ink composition produces markings composed of an inner silver portion with an outer blue contour line therearound.

Example 3 An ink composition was formulated in the same manner as in Example 2 except that only 5 parts of glycerine were used and 1 part of polyvinyl alcohol (Kuraray Co., Ltd., Poval 420) was also added. The water-based ink composition writes on paper to provide markings the same as those of Example 2.

Example 4 The following ink composition was formulated in the same manner as in Example 1: 30 parts of C.l. Solvent Red 49 (Orient Chemical Co., Ltd., Oil Pink #312) 1 part of C.l. Solvent Blue 25 (BASF, Neozapon Blue FLE) 10 parts of alkyd resin (Japan Reichhold Chemicals, Inc., Styresol J-718, resin content about 50%, solvent mineral turpentine) 4 parts of xylene resin (Mitsubishi Gas Kagaku K.K., Nikanol HP 100) 3 parts of indene-coumarone resin (Nittetsu Chemical Industrial Co., Ltd., Nittetsu Coumarone V-120) 10 parts of aluminum powder paste (Toyo Aluminum Co., Ltd., Alpaste 0230T, non-volatile content 80.7%) 30 parts of n-butyl acetate 53.5 parts of xylene.

The solvent-based ink composition writes on paper to provide markings composed of an inner silver portion with an outer violet contour line therearound.

Example 5 The following solvent-based ink composition was formulated in the same manner as in Example 1: 5 parts of amine salt of C.l. basic Red 1 (Hodogaya Chemical Co., Ltd., Spilon Red CGH) 10 parts of phenol resin (Hitachi Kasei Kogyo K.K., Hitanol 1133) 5 parts of xylene resin (as Example 4) 1 5 parts of bronze powder pigment (as Example 1) 4 parts of amyl acetate 73 parts of n-butyl acetate.

The ink composition writes on paper to form marking composed of an inner golden portion with an outer red contour line.

Example 6 The following solvent-base ink composition was formulated in the same manner as in Example 1: 18 parts of fluorescent pigment (Sinloihi Co., Ltd., Sinloihi Color EXL 1539F) 5 parts of acrylic resin (Rohm and Haas, Japan K.K., Acryloid B66) 10 parts of aluminum powder paste (Alpaste 0230T, as Example 4) 43 parts of isobutyl acetate 4 parts of isopropanol 20 parts of toluene.

The ink composition writes on paper to provide markings composed of an inner silver portion with an outer pink contour line therearound.

Example 7 The following mixture was stood overnight in a closed vessel at room temperature to swell the resin on the pigment in the solvent, and then stirred for 2 hours at room temperature: 7 parts of resinated pigment (0.2 microns, CIBA, Microlith Brown 2RK) 1 5 parts of. bronze powder pigment (Fukuda Metals K.K., #7770) 78 parts of n-butyl acetate.

The ink composition writes on paper to form markings composed of an inner golden portion with an outer brown contour line therearound.

Example 8 The following ink composition was formulated in the same manner as in Example 1: 5 parts of C.I. Solvent Red 18 (Orient Chemical Co., Ltd., Oil Scarlet #308S) 10 parts of resinated titanium oxide pigment (Dainichi Seika Color 8 Chemicals Mfg. Co., Ltd., PAGC 7807 White) 9 parts of petroleum resin (Nippon Sekiyu Kagaku Kogyo K.K., Neopolymer 140) 0.8 parts of nonionic surfactant (Neos K.K., Neosulmin S/M) 10 parts of aluminum powder paste (Alpaste 0230T, as Example 4) 65.2 parts of xylene.

The ink composition writes on paper to provide markings composed of an inner silver portion with an outer red contour line therearound.

Example 9 The following solvent-based ink composition was formulated in the same manner as in Example 1: 5 parts of amine salt of C.l. Basic Red 1 (as Example 5) 10 parts of phenol resin (as Example 5) 5 parts of xylene resin (as Example 4) 10 parts of bronze powder pigment (BS 947, as Example 1) 5 parts of aluminum powder paste (Alpaste 0230T, as Example 4) 4 parts of amyl acetate 73 parts of n-butyl acetate.

The ink composition forms markings composed of an inner golden white portion with an outer red contour line therearound.

Example 10 The following ink composition was prepared in the same manner as in Example 1: 2 parts of C.I. Acid Red 92 (as Example 1) 2 parts of sodium carboxymethylcellulose (as Example 1) 20 parts of ethyleneglycol 2 parts of ethyleneglycolmonobutylether 0.2 parts of surfactant polyoxyethyleneoleylether (Noigen P, as Example 1) 1 part of sodium benzoate 6 parts of carbon black (8 microns) 60 parts of water.

The ink composition writes on a pervious surface to form markings composed of an inner black portion with an outer red contour line therearound.

Example 11 Ten parts of the ammonium salt of a copolymer consisting of ethyl methacrylate-butyl methacrylate-hydroxyethyl methacrylatemethacrylic acid (mole ratio 25/40/20/1 5), 20 parts of ethylene-glycol, 5 parts of dipropyleneglycol, 1 5 parts of quinacridone red pigment, 20 parts of thiourea and 40 parts of water were stirred with a paint shaker for 2 hours at room temperature, and to the resultant mixture were further added 20 parts of ethyleneglycol and 40 parts of water and stirring continued for another 10 minutes. Coarse pigment particles were filtered off to provide an aqueous dispersion containing 8.8% by weight of pigment (0.08 microns).

Then the following ink composition was formulated in the same manner as in Example 1: 10 parts of above pigment dispersion 5 parts of glycerine 1 5 parts of ethyleneglycol 0.2 parts of surfactant polyoxyethyleneoleylether (Scourol #400, as Example 2) 1 part of sodium benzoate 5 parts of ultramarine blue (40 microns, Daiichi Kasei Kogyo K.K.) 61.6 parts of water.

The ink composition writes on paper to provide markings composed of an inner blue portion with an outer red contour line therearound.

Example 12 The following solvent-based ink composition was prepared in the same manner as in Example 1: 6 parts of C.l. Solvent Red 49 (as Example 4) 1 part of C.l. Solvent Blue 25 (as Example 4) 10 parts of alkyd resin (as Example 4) 4 parts of xylene resin (as Example 4) 2 parts of indene-coumarone resin (as Example 4) 6 parts of carbon black (8 microns) 30 parts of n-butyl acetate 53.5 parts of xylene.

The ink composition provides markings composed of an inner black portion with an outer violet contour line therearound.

Example 13 The following ink composition was formulated in the same manner as in Example 1. The ink composition writes on paper to form markings composed of an inner yellow portion with an outer red contour line therearound.

5 parts of amine salt of C.l. Basic Red 1 (as Example 5) 10 parts of phenol resin (as Example 5) 5 parts of xylene resin (as Example 4) 7 parts of cadmium yellow (20 microns, Toyo Ganryo Ind. Co., Ltd.) 4 parts of amyl acetate 73 parts of n-butyl acetate.

Example 14 The following ink composition formulated in the same manner as in Example 1 writes on paper to provide markings composed of an inner blue portion with an outer pink contour line therearound.

1 8 parts of fluorescent pigment (as Example 6) 5 parts of acrylic resin (as Example 6) 6 parts of cobalt blue (45 microns, Toyo Ganryo Ind. Co., Ltd.) 43 parts of isobutyl acetate 4 parts of isopropanol 20 parts of toluene.

Example 15 The following ink composition was formulated in the same manner as in Example 1: 4 parts of pigment (0.09 microns, Dainichi Seika Color 8 Chemicals Mfg. Co., Ltd., PAGC 7221 Red) 9 parts of petroleum resin (as Example 8) 0.8 parts of surfactant (Neosulmin, as Example 8) 5 parts of viridian (30 microns, Toyo Ganryo Ind. Co., Ltd., Viridian 3B) 65.2 parts of xylene.

The solvent-based ink composition writes on paper to provide markings composed of an inner brown portion with an outer rosy contour line therearound.

Example 16 The following ink composition was formulated in the same manner as in Example 1: 3 parts of pigment (0.1 microns, Dainichi Seika Color s Chemicals Mfg. Co., Ltd., PAGC 7122 Yellow) 10 parts of phenol resin (as Example 5) 5 parts of xylene resin (as Example 4) 6 parts of burnt umber (35 microns, Mie Ganryo K.K.) 4 parts of amyl acetate 73 parts of n-butyl acetate.

The solvent-based ink composition writes on paper to provide markings composed of an inner dark brown portion with an outer yellow contour line therearound.

Example 17 The following mixture was stood overnight in a closed vessel at room temperature to swell the resin on the pigment: 7 parts of resinated pigment (Microlith Brown 2RK, as Example 7) 5 parts of carbon black (8 microns) 78 parts of n-butyl acetate.

The mixture was then stirred for 2 hours at room temperature to provide a solvent-base ink composition. The ink composition writes on paper to provide markings composed of an inner black portion with an outer brown contour line therearound.

Claims (10)

Claims

1. A dual color ink composition comprising a solvent and at least two coloring agents dissolved or dispersed in the solvent, the coloring agent comprising: (a) a first pigment of a first color having a particle size such that the pigment is substantially retained on a permeable writing surface; and (b) a dyestuff of a second color soluble in the solvent or a pigment of a second color and of a particle size smaller than the particle Bize of the first pigment and such that the second pigment passes with the solvent through the permeable writing surface.

2. An ink composition which comprises 2080% by weight of a solvent, not more than 30% by weight of a resin soluble in the solvent, and coloring agents dissolved or dispersed in the solvent, the coloring agents comprising: (a) 360% by weight of a first pigment of a first color not less than 0.5 microns in the maximum frequency particle size, and (b) 0.1-20% by weight of a dyestuff of a second color soluble in the solvent or a second pigment of a second color smaller than the first pigment and not more than 1 micron in the maximum frequency particle size in particle size distribution.

3. An ink composition according to claim 1 or claim 2, wherein the pigments are selected from metal powder pigments, inorganic pigments and organic pigments.

4. An ink composition according to any one of claims 1 to 3, wherein the solvent is a mixture of water and at least one water-soluble organic solvent.

5. An ink composition according to any one of claims 1 to 3, wherein the solvent is selected from alicyclic hydrocarbons, aliphatic hydrocarbons, aromatic hydrocarbons, aliphatic ketones, alicyclic ketones, aliphatic carboxylic acid alkyl esters, aliphatic alcohols and ethyleneglycolmonoalkylethers.

6. An ink composition according to claim 2 which comprises: 3570% by weight of the solvent, 120% by weight of the resin, 1 0-40% by weight of the first pigment, and 0.5-1 5% by weight of the dyestuff and/or the second pigment.

7. An ink composition according to any one of claims 1 to 6, which further comprises effective amounts of at least one additive selected from surfactants, antiseptics and rust-preventive agents.

8. An ink composition according to any one of claims 1 to 7, wherein the first pigment has a particle size of not less than 2 microns in the maximum frequency particle size.

9. An ink composition substantially as described in any one of the Examples herein.

10. A writing instrument having a reservoir of an ink composition according to any one of claims 1 to 9.