JP2003128960A - White ink composition - Google Patents

Abstract

[57] [Abstract] [Problem] It is possible to print, draw and write on non-absorbing surfaces of resin sheets, cloths, resin plates, surface coated papers, metal plates, glass, leather, pottery, wood, rubber, etc., and discharge is stable. To provide a white ink composition having excellent properties. SOLUTION: Titanium oxide, ethyl lactate, propyl lactate, butyl lactate, cyclohexanone, cyclohexanol, 3-methyl-3-methoxybutanol, ethylene glycol monobutyl ether acetate, methyl benzoate, etc.
A white ink composition containing at least a polar organic solvent having a boiling point of 150C to 200C.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is capable of printing, drawing and writing on not only paper but also resin sheets, cloths, resin plates, surface coated paper, metal plates, glass, leather, pottery, wood, rubber and the like. The present invention relates to a white ink composition having excellent discharge stability.

[0002]

2. Description of the Related Art Heretofore, an ink using titanium oxide as a pigment has been known as a coloring material capable of obtaining white handwriting. In addition to ink that imparts white-based handwriting, etc. to a recording medium such as black, a correction liquid that is overcoated to correct recorded characters and images and that allows rewriting on it is known. .

As the liquid medium for dispersing the titanium oxide, in addition to water, alcohol solvents such as ethyl alcohol and isopropyl alcohol, glycol ether solvents such as ethylene glycol monoethyl ether and propylene glycol monomethyl ether, ethyl acetate, Ester solvents such as butyl acetate, ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone, n-hexane,
Organic solvents such as hydrocarbon solvents such as isooctane, n-octane, methylcyclohexane, cyclopentane, toluene and xylene are known.

[0004]

Titanium oxide is known as a white pigment having a large specific gravity, and there is a problem that it tends to settle and agglomerate to form a hard cake, which makes it difficult to flow. When used by directly filling the ink tank of a writing instrument or applicator with a built-in liquid, place a stirrer such as a bead or rod in the ink tank and shake the container to remove the titanium oxide in the ink. Although it has been devised to redisperse, it has the trouble of having to shake the container each time it is used, and if it is not used for a long time,
In some cases, re-dispersion was not possible even with a stirrer.

In particular, when the ink is used for an on-demand type ink jet printer, the ink jet recording system ejects ink droplets from a thin nozzle as required to directly attach the ink to a printing medium. However, the problem of nozzle clogging due to ink sticking at the nozzle tip, titanium oxide settling and aggregation cannot be solved, and it has not yet been put to practical use.

[0006]

DISCLOSURE OF THE INVENTION The gist of the present invention is a white ink composition containing at least titanium oxide and a polar organic solvent having a boiling point of 150 ° C. to 200 ° C.

The present invention will be described below. Titanium oxide imparts a concealing property, and both rutile type and anatase type can be used. As an example of a commercially available product, Titatone SR-1 and R
-650, the same R-3L, the same R-7E, the same R-5N, the same A
-110, A-150, Taipaque R-580, R-560, R-930, A-1 manufactured by Ishihara Sangyo Co., Ltd.
00, A-220, CR-58, Titanium Industry Co., Ltd.
Chronos KR-310, KR-380, KR3
80N, KR-480, KA-10, KA-2
0, the same KA-30, TYPURE R-900, the same R-931 manufactured by DuPont Japan Limited, the Titanics JR-300, the same JR-600A, the same JR manufactured by Teika Co., Ltd.
701, the same JR-800, the same JR-801, the Bayer Titanium R-FD-1 and the same R-FB- manufactured by Bayer in Germany.
3, the same RD and the like. These titanium oxides are
One kind or a mixture of two or more kinds can be used, and the use amount thereof can be 10 to 30% by weight, and preferably 15 to 2% by weight, based on the total amount of the ink composition. The maximum particle size of titanium oxide is preferably 3 μm or less. The measuring method includes a centrifugal sedimentation type particle size distribution measuring device and a laser type particle size distribution measuring device, but the latter was adopted this time. .

A polar organic solvent having a boiling point of 150 to 200 ° C. is used as a dispersion medium for titanium oxide. When used in an ink jet printer, clogging due to drying of the nozzle tip is suppressed, and the printing and drawing surfaces have good drying properties, which also contributes to the dispersion stability of titanium oxide. If the boiling point is too low, the tip of the nozzle tends to dry, and if the boiling point is too high, the drying of the printing and drawing surfaces will be slow and storage will be hindered. Specific examples thereof include ethyl lactate, propyl lactate, butyl lactate, cyclohexanone, cyclohexanol, 3-methyl-3-methoxybutanol, ethylene glycol monobutyl ether acetate, methyl benzoate and the like. These polar organic solvents may be used alone or in combination of two or more. The amount used is preferably 40 to 60% by weight with respect to the total amount of the white ink composition for ink jet recording. Further, by improving the solubility of the resin, printing, improving the drying property of the drawing surface, improving the leveling property, the viscosity of the ink, the adjustment of other physical properties, etc., a non-polar organic solvent or an organic solvent having a boiling point of 150 ° C. or less, You may use together the organic solvent of 200 degreeC or more.

The viscosity of the ink is 8 mPa · s or more and 15 m
It is preferable that the viscosity of the ink is 15 mPa · s because the inner diameter of the nozzle that ejects the ink is very small, especially when used for ink jet recording.
If it exceeds S, ejection may become unstable or ejection may become impossible. On the other hand, when the viscosity of the ink is less than 8 mPa · S, the ejected ink is dripped and the printed surface and the drawing surface lack sharpness. In particular, it was remarkable when the printed surface was a non-absorption surface.

In addition to the above essential components, various materials can be blended. The resin is used as a dispersant and a dispersion stabilizer for improving the fixability and strength of the printing surface and the drawing surface. Specific examples thereof include acrylic resin, styrene / acrylic resin, vinyl acetate / acrylic resin, urethane / acrylic resin, silicone / acrylic resin, other acrylic copolymer resin, polyvinyl butyral resin, polyester resin,
Vinyl acetate resin, ethylene vinyl acetate resin, rosin-modified maleic acid resin, xylene resin, rosin-modified xylene resin, ester gum, ketone resin, nitrocellulose, phenol resin, rosin-modified phenol resin, alkylphenol resin, alkylphenol resin, terpene-modified phenol resin , Glycerin ester of rosin and the like. These resins can be used alone or in combination of two or more, and the amount thereof can be used in an amount of 2 to 12% by weight based on the total amount of the white ink composition for ink jet recording,
It is preferably 4 to 8% by weight.

In addition to the above components, various conventionally used additives can be used. For example, a color pigment may be used in combination to adjust the color tone, and an extender pigment such as silica powder, aluminum silicate, or calcium carbonate may be used in combination to further improve the hiding power. In addition, a dispersant or sedimentation preventive agent for improving dispersibility, a thickener agent for adjusting viscosity, a plasticizer agent for adjusting hardness of a printing surface or a drawing surface,
A flow improver or a leveling agent may be added as appropriate in order to improve the coating performance.

The white ink composition of the present invention can be obtained by dispersing and mixing the above components using a disperser such as a Dyno mill, a ball mill, an attritor or a sand grinder.

[0013]

The ink of the present invention has less aggregation and settling, and when used in an on-demand type ink jet printer, the ink is hardly fixed at the tip of the nozzle and the ejection is stable as follows. Inferred. Since the titanium oxide dispersed in the fine particles is present in the polar organic solvent, the dispersion of titanium oxide is not hindered, the aggregation and precipitation of titanium oxides are suppressed, and the stability of titanium oxide dispersion is maintained. . Further, the boiling point of the polar organic solvent of the present invention is 150 ° C.
Since the temperature is up to 200 ° C., it is difficult to evaporate at room temperature, and it is presumed that the ink is prevented from thickening and sticking due to the evaporation of the solvent in the ejection portion during printing and writing, and the ink ejection is stable. In particular, by using an acrylic resin as the resin, contact between the surfaces of titanium oxides is suppressed, and the dispersion of titanium oxides becomes stable.

[0014]

Example 1 Chronos titanium KR380 (rutile type titanium oxide, manufactured by Titanium Industry Co., Ltd.) 20 parts by weight Kyoward 700 (aluminum silicate, manufactured by Kyowa Chemical Industry Co., Ltd.) 3 parts by weight Acryloid B-66 ( Acrylic resin, manufactured by Rohm and Haas Japan Co., Ltd. 6 parts by weight Homogenol L-18 (dispersant, manufactured by Kao Soap Co., Ltd.) 1.2 parts by weight Butyl lactate (boiling point, 187 ° C.) 49 parts by weight Methyl Cyclohexane (boiling point, 101 ° C.) 20.8 parts by weight The above components were dispersed in a ball mill for 24 hours to obtain a white ink composition having a viscosity of 11.6 mPa · S (25 ° C.) 1.2 μm.

Example 2 Titanics JR-800 (rutile type titanium oxide, manufactured by Teika Co., Ltd.) 20 parts by weight Acryloid B-67 (acrylic resin, manufactured by Rohm and Haas Japan Co., Ltd.) 5 parts by weight Disperk 180 (dispersing agent, manufactured by BYK Japan KK) 1 part by weight Cyclohexanone (boiling point, 155.7 ° C.) 25 parts by weight Ethylene glycol monobutyl ether acetate (boiling point, 191.5 ° C.) 49 parts by weight Same as No. 1, viscosity 9.2 mPa
A white ink composition having an S (25 ° C.) of 1.9 μm was obtained.

Example 3 Titone R62N (rutile type titanium oxide, manufactured by Sakai Chemical Industry Co., Ltd.) 18 parts by weight Mizukasil P-801 (fine silica, manufactured by Mizusawa Chemical Co., Ltd.) 2 parts by weight Acryloid B-66 (described above) 4 parts by weight Hirac 111 (ketone resin, manufactured by Hitachi Chemical Co., Ltd.) 4 parts by weight homogenol L-18 (described above) 1.2 parts by weight butyl lactate (boiling point, 187 ° C.) 59 parts by weight methylcyclohexane (described above) 11 0.8 parts by weight The above components were added in the same manner as in Example 1 to give a viscosity of 13.1 mP
A white ink composition having a.S (25 ° C.) and a maximum particle size of 1.3 μm was obtained.

Example 4 Chronos titanium KR380 (described above) 22 parts by weight Acryloid B-37 (described above) 4 parts by weight Polyvinyl butyral 2000L (manufactured by Denki Kagaku Kogyo Co., Ltd.) 2 parts by weight Butyl lactate (boiling point, 187 ° C.) 49 parts by weight Parts Methylcyclohexane (previously described) 15 parts by weight 3 Methyl 3 methoxybutanol (boiling point 178 ° C.) 8 parts by weight The above components were processed in the same manner as in Example 1 to obtain a viscosity of 14.4 mP.
A white ink composition having a.S (25 ° C.) and a maximum particle size of 1.5 μm was obtained.

Comparative Example 1 The same procedure as in Example 1 was repeated except that n-decane (nonpolar organic solvent, boiling point 174 ° C.) was used instead of butyl lactate, and the viscosity was 13.3 mPa · S. (25
A white ink composition of (° C.) was obtained.

Comparative Example 2 The procedure of Example 1 was repeated except that benzyl alcohol (polar organic solvent, boiling point 205.8 ° C.) was used instead of butyl lactate, and the viscosity was 14.1 mPa · s.
A white ink composition of S (25 ° C.) was obtained.

Comparative Example 3 The procedure of Example 1 was repeated except that ethylcyclohexane (nonpolar organic solvent, boiling point 132 ° C.) was used instead of butyl lactate, and the viscosity was 11.2 mPa · s.
A white ink composition of S (25 ° C.) was obtained.

Comparative Example 4 A white ink having a viscosity of 7.5 mPa · S (25 ° C.) was prepared in the same manner as in Example 1, except that 6 parts by weight of Acryloid B-66 and 52 parts by weight of butyl lactate were used in Example 1. A composition was obtained.

Comparative Example 5 In Example 4, the polyvinyl butyral 2000L was changed to 2.5 parts by weight and the butyl lactate was changed to 48.5 parts by weight,
In the same manner as in Example 4, the viscosity was 16.3 mPa · S (2
A white ink composition (5 ° C.) was obtained.

The white ink compositions obtained in Examples 1 to 4 and Comparative Examples 1 to 5 were subjected to a dispersion stability test and a discharge stability test. The results are shown in Table 1.

Dispersion Stability Test Each white ink composition was placed in a vial bottle up to a height of 5 cm, allowed to stand at room temperature (20 ° C.), and the number of days when a sediment could be confirmed at the bottom was measured with a micro spatula.

Discharge stability test An ink jet printer (ADOPICTO 1, Pentel Co., Ltd., on-demand type) was used to print on a black resin sheet, and the time when blurring of the print occurred was measured.

[0026]

[Table 1]

[0027]

As described above in detail, the white ink composition of the present invention is excellent in dispersion stability, and in particular, when used in an on-demand type ink jet printer for a long time, the pigment aggregates and precipitates. The white ink composition is excellent in ejection stability because the nozzle is not clogged with the ink, and the tip of the nozzle is not fixed due to drying of the ink.

Claims (5)

[Claims] 1. A white ink composition containing at least titanium oxide and a polar organic solvent having a boiling point of 150 ° C. to 200 ° C. 2. The white ink composition according to claim 1, which is for ink jet recording. 3. The white ink composition according to claim 1, which has a viscosity of 8 to 15 mPa · S. 4. The white ink composition according to claim 1, which contains an acrylic resin. 5. The white ink composition according to claim 1, wherein the maximum particle size of titanium oxide is 3 μm or less.