JPH1112523A - Ink jet ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject ink good in deliverability, stable in the dispersion of pigment therein, hard to develop pigment sedimentation with the lapse of time, and useful in piezotype ink jet printers of on-demand system, by including a pigment, water and a specified amount of a specific dispersant. SOLUTION: This ink is obtained by including 0.5-30 wt.%, based on the total weight of the ink, of a pigment (e.g. carbon black, phthalocyanine-based pigment) and 0.03-20 wt.%, based on the total weight of the ink, of a dispersant, i.e., at least one material selected from shellac, humic acid and nitrohumic acid; in this case, it is preferable that the effective amount of the dispersant to be used is 0.3-20 pts.wt. based on 10 pts.wt. of the pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet ink, and more particularly to a piezo type ink jet printer of an on-demand type (ink droplets only when required by a pressure instantaneously generated by vibration of a piezoelectric vibrator). The present invention relates to an ink which has good dischargeability when used in an ink jet printer of a type in which ink is ejected and prints, has a stable pigment dispersion, and is unlikely to cause sedimentation of the pigment over time.

[0002]

2. Description of the Related Art It is known that a surfactant or a resin is used as a dispersant in an ink using a pigment.
Typical examples of using a resin as a dispersant include a styrene-acrylic acid copolymer and a styrene-maleic acid copolymer.

[0003]

However, inks using the above-mentioned conventionally used dispersants such as styrene-acrylic acid copolymer and styrene-maleic acid copolymer have insufficient dispersion stability. For this reason, when the printer head is stored for a long time, there is a problem that the pigment sediments with time and the nozzles of the head are clogged. In addition, when the effect of preventing pigment sedimentation is increased by increasing the amount of the dispersant, there is a problem that the viscosity of the ink becomes too high to obtain good ejection.

[0004]

That is, the present invention relates to an ink for ink jet comprising at least a pigment, a dispersant, and water, wherein the dispersants are shellac, humic acid,
An ink jet ink characterized in that one or more selected from nitrohumic acid is used in an amount of 0.03 to 20 parts by weight based on the total amount of the ink.

Hereinafter, the present invention will be described in detail. The pigment is used for coloring, and generally used pigments can be used without any problem. Examples of the pigment include carbon black, phthalocyanine pigments, azo pigments, quinacridone pigments, and isoindolinone. System, benzimidazolone system, perylene system, dioxazine system, indanthrene system and the like. The amount used is preferably 0.5 to 30% by weight of the total ink. If it is less than 0.5% by weight, the printing density is low, and if it exceeds 30% by weight, the viscosity of the ink becomes too high, the ejection property becomes insufficient, and the printing quality deteriorates.

[0006] Shellac is a resin obtained by purifying the secreted product of Lacquerbug insects, and its structure is presumed.
Lactide is composed of 2 mol of aliuritic acid, 2 mol of shellol acid and 4 mol of shellac resin acid. There are various types of shellac, such as purified white shellac, purified wax-containing shellac, and purified dewaxed shellac, all of which can be used. Is not affected. Products include Shellac NSC, CS, SSI, SSJ, SST, NST, G manufactured by Nippon Shellac Industry Co., Ltd.
N, L, dried transparent white rack, dried milky white rack, Co., Ltd.
Gifu shellac factory transparent white rack GBN-D, GB
N, milky white racks GB-D, GB and the like. Humic acid is obtained by extracting coal or soil with low carbonization with an alkaline solution, or by treating ordinary coal with an oxidizing agent, and any one obtained by any method can be used. The following formula is accepted as the descriptive formula, and the molecular weight is 103 to 10
6. Commercially available C ₇₈ H ₅₂ O ₅ (COOH) ₈ (OH) ₇ (CO) ₂ humic acids include CH-02, CHA-02 (above aqueous sodium humate solution) and CHA-02 manufactured by Ternite Co., Ltd. -07, CHA-07 (an aqueous solution of ammonium humate). Nitrohumic acid is obtained by oxidizing coal with nitric acid. The following general formula is accepted as the general descriptive formula, and the molecular weight is 103 to
106. C ₄₉ H ₄₄ O ₁₀ (COOH) ₅ (OH) ₆ (CO) ₄ (N
O ₂ ) ₃ (NOH) Commercially available is NHA nitrohumate manufactured by Terunite Co., Ltd. Shellac, humic acid as a dispersant,
Nitrohumic acid is used as a water-soluble salt form. Examples of the salt form include alkali metal salts such as lithium, sodium, and potassium, ammonium salts, amine salts, and alkanolamine salts. The effective amount of shellac, humic acid and nitrohumic acid is based on 10 parts by weight of the pigment.
0.3 to 20 parts by weight. If the amount is less than 0.3 parts by weight, the effect of dispersion stability is weak, and if it exceeds 20 parts by weight, the effect may not be improved, but it is uneconomical. On the other hand, if the amount added to the total amount of the ink is more than 20 parts by weight, the viscosity of the ink becomes too high, and the ejection property deteriorates, and the nozzles of the head easily dry.

[0007] Water is used as the main solvent.

In addition to these, water-soluble organic solvents, for example, polyhydric alcohols such as ethylene glycol and glycerin, polyalkylene oxides, pyrrolidones, formamide, urea and derivatives thereof for the purpose of preventing the nozzles of the head from drying. The various humectants and hygroscopic agents are surfactants for adjusting the penetrating power and ink mobility, specifically alkyl ethers of polyalkylene oxides, alkyl phenyl ethers, various anionic activators, silicones, Fluorinated surfactants, etc. Further, a pH adjuster, a preservative, a rust inhibitor, a viscosity adjuster such as various water-soluble polymers and the like can be appropriately used as needed.

The ink of the present invention comprises shellac, humic acid,
A pigment is added to one or more aqueous solutions selected from nitrohumic acid, and the resultant is dispersed by a conventional general disperser, for example, a three-roll mill, a Dyno mill, a sand mill, and the like, and then added with other necessary components. However, if necessary, centrifugation may be performed to remove coarse particles. Although a general method for obtaining the ink of the present invention has been described, the present invention is not limited to this method, and various methods may be appropriately selected and used.

[0010]

Although it is not clear why good dispersion stability can be obtained when shellac, humic acid or nitrohumic acid is used as a dispersant for a pigment, it is presumed as follows. Shellac, humic acid, and nitrohumic acid do not have very large molecular weights.
There are many phenolic hydroxyl groups and carboxyl groups in the molecule. When this is converted into an aqueous solution with an alkalizing agent, these hydroxyl groups and carboxyl groups become negative ions, and the molecule is wrapped by a large number of negative ions. When the dissolved shellac, humic acid, and nitrohumic acid are adsorbed on the pigment, the ions cause strong surface electricity.
An overlay is formed. This is presumed to cause strong repulsion of ions between the pigments and prevent sedimentation due to aggregation of the pigments. Further, a large number of hydrogen bonds are formed between the negative ions of shellac, humic acid, and nitrohumic acid adsorbed on the pigment surface and water as a solvent, and a strong solvent affinity is generated. As a result, it is assumed that sedimentation of the pigment is prevented. Note that shellac, humic acid, and nitrohumic acid are more effective in stabilizing the dispersion of pigments than conventional styrene-maleic acid copolymers or styrene-acrylic acid copolymers because of the ratio of hydroxyl groups and carboxyl groups in the molecule. It is presumed that it is much larger.

[0011]

The present invention will be described in more detail with reference to the following examples. In the examples, “parts” means “parts by weight”.

Example 1 Printex 90 (carbon black, manufactured by Degussa Japan Co., Ltd.) 7.6 parts Shellac GBN-D (refined white shellac, dispersant, Gifu Shellac Manufacturing Co., Ltd.) 1.5 parts Sodium hydroxide 0.6 part Nikkor NP-10 (POE nonyl phenyl ether, penetrant, Nikko Chemicals Co., Ltd.) 0.2 parts Ethylene glycol 12.0 parts Proxel GX-L (1,2-benzisothiazoline-) 3-one, preservative, manufactured by Zeneca Co., Ltd.) 0.2 part Ion-exchanged water 78.9 parts Of the above components, the total amount of shellac GBN-D, sodium hydroxide and 23 parts of ion-exchanged water were mixed, and After heating and stirring at 50 ° C. to uniformly dissolve, the mixture was allowed to cool to room temperature, and Printex 90 was added thereto, followed by stirring and mixing until the mixture became uniform. This was passed ten times with three rolls and kneaded to obtain a pigment paste. Next, the remaining components were mixed, and the pigment paste was added to the uniformly dissolved liquid, and the mixture was stirred for 1 hour until the mixture became uniform. The mixture was centrifuged at 7000 rpm for 1 hour to obtain a black ink.

Example 2 KET RED 336 (CI. PIGMENT VIOLET 19, pigment, manufactured by Dainippon Ink and Chemicals, Inc.) 5.8 parts Shellac GBN-D 3.5 parts Sodium hydroxide 0.2 parts Nikkor NP-10 0.1 part Ethylene glycol 10.0 part Proxel GX-L 0.2 part Ion exchange water 80.2 part Of the above components, shellac GBN-D, the total amount of sodium hydroxide and 23 parts of ion exchange water are mixed. After heating and stirring at about 50 ° C. to dissolve uniformly, the mixture was allowed to cool to room temperature,
ET RED 336 was added and stirred and mixed until uniform. This was passed ten times with three rolls and kneaded to obtain a pigment paste. Next, the remaining components were mixed, and the pigment paste was added to the uniformly dissolved liquid, and the mixture was stirred for 1 hour until the mixture became uniform, and centrifuged at 7000 rpm for 1 hour to obtain a red ink.

Example 3 PV First Yellow H2G01 (CI Pigment Yellow 120, Pigment, manufactured by Hoechst) 3.5 parts Shellac GBN-D 1.6 parts Ammonia water (29% ammonia) 0.4 part Neugen -P (POE lauryl ether, penetrant, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 0.1 part N-vinyl-2-pyrrolidone 10.0 parts Proxel GX-L 0.2 parts Deionized water 84.2 parts Among the components, shellac GBN-D, the total amount of aqueous ammonia and 38 parts of ion-exchanged water were mixed and uniformly dissolved by stirring, and then PV Fast Yellow H2G0 was added thereto.
1 was added and stirred and mixed until uniform. This was passed through a Dyno mill 10 times and kneaded to obtain a pigment paste. Next, the remaining components were mixed, and the pigment paste was added to the uniformly dissolved liquid. The mixture was stirred for 1 hour until the mixture became uniform, and centrifuged at 7000 rpm for 1 hour to obtain a yellow ink.

Example 4 KET BLUE 104 (CI PIGMENT BLUE 15: 3, pigment, Hoechst) 4.5 parts Shellac GBN-D 2.6 parts ammonia water (29% ammonia) 0.5 part Neugen-P 0.1 part Diethylene glycol 10.0 part Proxel GX-L 0.2 part Ion-exchanged water 82.1 parts Among the above components, shellac GBN-D, the total amount of ammonia water and 38 parts of ion-exchanged water are mixed, After stirring to dissolve uniformly, KET BLUE 104 was added thereto, followed by stirring and mixing until the mixture became uniform. This is a Dyno mill 1
The mixture was kneaded for 0 times to obtain a pigment paste. Next, the remaining components were mixed, the pigment paste was added to the uniformly dissolved liquid, and the mixture was stirred for 1 hour until the mixture became uniform.
m for 1 hour to give a blue ink.

Example 5 Printex 90 1.0 part Shellac GBN-D 0.03 part Ammonia water (29% ammonia) 0.01 part Neugen-P 0.2 part Diethylene glycol 10.0 parts Proxel GX-L 2 parts Ion-exchanged water 88.56 parts Among the above components, shellac GBN-D, the total amount of aqueous ammonia and 20 parts of ion-exchanged water are mixed and uniformly dissolved by stirring. And stirred until the mixture became. This was passed through a Dyno mill 10 times and kneaded to obtain a pigment dispersion. Next, the remaining components were mixed, the pigment dispersion was added to the uniformly dissolved liquid, and the mixture was stirred for 1 hour until the mixture became uniform, and the mixture was centrifuged at 7000 rpm for 1 hour to obtain a black ink.

Example 6 KET BLUE 104 3.8 parts Shellac GBN-D 20.0 parts Ammonia water (29% ammonia) 5.6 parts Neugen-P 0.1 parts Diethylene glycol 10.0 parts Proxel GX-L 0. 2 parts ion-exchanged water 30.3 parts shellac GBN-D and the whole amount of ammonia water and 10 parts of ion-exchanged water among the above components were mixed and stirred to dissolve uniformly, and then KET BLUE 104 was added thereto and homogenized. And stirred until the mixture became. This is a Dyno mill 1
The mixture was kneaded for 0 times to obtain a pigment paste. Next, the remaining components were mixed, the pigment paste was added to the uniformly dissolved liquid, and the mixture was stirred for 1 hour until the mixture became uniform.
m for 1 hour to give a blue ink.

Example 7 Printex 90 (carbon black, manufactured by Degussa Japan Co., Ltd.) 7.6 parts CH-02 humic acid (sodium humate, manufactured by Ternite Co., Ltd.) 1.5 parts Nikkor NP-10 ( POE nonylphenyl ether, penetrant, Nikko Chemicals Co., Ltd. 0.2 part Ethylene glycol 12.0 parts Proxel GX-L (1,2-benzisothiazolin-3-one, preservative, Zeneca Corporation) 0.2 parts ion-exchanged water 78.5 parts Of the above components, humic acid CH-02 and ion-exchanged water 23
The parts were mixed and heated and stirred at about 50 ° C. to dissolve uniformly, and then allowed to cool to room temperature. Then, Printex 90 was added thereto and stirred and mixed until uniform. This is three rolls for one
The mixture was kneaded for 0 times to obtain a pigment paste. Next, the remaining components were mixed, the pigment paste was added to the uniformly dissolved liquid, and the mixture was stirred for 1 hour until the mixture became uniform.
m for 1 hour to obtain a black ink.

Example 8 Printex 90 (carbon black, manufactured by Degussa Japan Co., Ltd.) 8.0 parts NHA nitrohumate (manufactured by Ternite Co., Ltd.) 2.5 parts Ammonia water (29%) 0.8 parts Nikkor NP-10 0.2 parts Diethylene glycol 8.0 parts Proxel GX-L 0.2 parts Ion-exchanged water 80.3 parts Of the above components, the total amount of NHA nitrohumate and ammonia water and 26 parts of ion-exchanged water are mixed. After heating and stirring at 50 ° C. to uniformly dissolve, the mixture was allowed to cool to room temperature, and Printex 90 was added thereto, followed by stirring and mixing until the mixture became uniform.
This was passed ten times with three rolls and kneaded to obtain a pigment paste. Next, the remaining components were mixed, and the pigment paste was added to the uniformly dissolved liquid, and the mixture was stirred for 1 hour until the mixture became uniform. The mixture was centrifuged at 7000 rpm for 1 hour to obtain a black ink.

Example 9 7.5 parts of KET BLUE 104 7.5 parts of CH-07 humic acid (ammonium humate, manufactured by Ternite Co., Ltd.) 1 part of Neugen-P 0.1 part 10.0 parts of diethylene glycol Proxel GX-L 0 .2 parts ion exchange water 67.2 parts humic acid CH-07 and ion exchange water 10
Parts were stirred and uniformly dissolved by stirring.
T BLUE 104 was added and stirred and mixed until uniform. This was passed through a Dyno mill 10 times and kneaded to obtain a pigment paste. Next, the remaining components are mixed, and the pigment paste is added to the uniformly dissolved liquid.
After stirring for 1 hour, the mixture was centrifuged at 7000 rpm for 1 hour to obtain a blue ink.

Example 10 KET RED 336 (CI PIGMENT VIOLET 19, pigment, manufactured by Dainippon Ink and Chemicals, Inc.) 4.6 parts Nitrohumic acid NHA 13.5 parts Sodium hydroxide 1.2 parts Nikkor NP -10 0.5 parts Ethylene glycol 10.0 parts Proxel GX-L 0.2 parts Ion-exchanged water 70.0 parts Of the above components, the total amount of nitrohumic acid NHA and sodium hydroxide and 23 parts of ion-exchanged water were mixed, After heating and stirring at about 50 ° C. to uniformly dissolve, the mixture was allowed to cool to room temperature, and KET RED 336 was added thereto, followed by stirring and mixing until the mixture became uniform. This was passed ten times with three rolls and kneaded to obtain a pigment paste. Next, the remaining components are mixed, and the pigment paste is added to the uniformly dissolved liquid.
After stirring for 1 hour, the mixture was centrifuged at 7000 rpm for 1 hour to obtain a red ink.

Example 11 Printex 90 (carbon black, manufactured by Degussa Japan K.K.) 7.0 parts Humic acid CH-07 1.5 parts Shellac GBN-D 1.0 part ammonia water (29%) 3 parts Nikkor NP-10 0.2 parts Diethylene glycol 8.0 parts Proxel GX-L 0.2 parts Ion-exchanged water 81.8 parts Shellac, humic acid CH-07, total amount of ammonia water and ion-exchanged water among the above components 26 parts, about 50 ° C
After heating and stirring to dissolve uniformly, the mixture was allowed to cool to room temperature, and Printex 90 was added thereto, followed by stirring and mixing until the mixture became uniform. This was passed ten times with three rolls and kneaded to obtain a pigment paste. Next, the remaining components are mixed, and the pigment paste is added to the uniformly dissolved liquid.
After stirring for 1 hour, the mixture was centrifuged at 7,000 rpm for 1 hour to obtain a black ink.

Example 12 Printex 90 (carbon black, manufactured by Degussa Japan KK) 4.0 parts Nitrohumic acid NHA 0.7 parts Humic acid CHA-07 (ammonium huminate, manufactured by Ternite Co.) 5 parts Ammonia water (29%) 0.2 parts Nikkor NP-10 0.1 parts Diethylene glycol 8.0 parts Proxel GX-L 0.2 parts Deionized water 86.3 parts Humic acid CHA-07, The total amount of NHA nitrohumate and aqueous ammonia and 26 parts of ion-exchanged water are mixed, and the mixture is heated and stirred at about 50 ° C. to dissolve uniformly, and then cooled to room temperature. Then, Printex 90 is added thereto and stirred until uniform. , Mixed. This was passed ten times with three rolls and kneaded to obtain a pigment paste. Next, the remaining components were mixed, and the pigment paste was added to the uniformly dissolved liquid, and the mixture was stirred for 1 hour until the mixture became uniform.
After centrifugation for hours, a black ink was obtained.

Comparative Example 1 A black ink was obtained in the same manner as in Example 1 except that SMA-1000A (styrene-maleic acid resin, dispersant, manufactured by Atochem) was used instead of shellac.

Comparative Example 2 A black ink was obtained in the same manner as in Example 1 except that the amount of shellac was reduced to 0.02 parts, and ion-exchanged water was added accordingly.

Comparative Example 3 A red ink was obtained in the same manner as in Example 2, except that the amount of shellac was increased to 32.0 parts and the amount of ion-exchanged water was reduced accordingly.

Comparative Example 4 A black ink was obtained in the same manner as in Example 7, except that the amount of humic acid CH-02 was reduced to 0.02 parts and ion-exchanged water was added accordingly.

Comparative Example 5 A blue ink was obtained in the same manner as in Example 9 except that the amount of humic acid CH-07 was increased to 32.0 parts, and ion-exchanged water was reduced accordingly.

[0029]

【The invention's effect】

Dispersion stability The inks of Examples 1 to 12 and Comparative Examples 1 to 5 have a length of 30 c.
m, placed in a test tube having an inner diameter of 1 cm at a height of 20 cm, allowed to stand at room temperature for one month, and then measured the height of the sediment. Ink Ejectability The inks of Examples 1 to 12 and Comparative Examples 1 to 5 were manufactured by Seiko Epson Inc., with an ink cartridge MJ1C1 for an ink jet printer (built-in piezoelectric vibrator type recording head).
And a pulse recording signal having a constant drive voltage of 25 V and an arbitrary frequency was applied to the piezoelectric vibrator of the head, and the maximum frequency of ink ejection corresponding to the frequency was determined. The higher the frequency, the better the responsiveness of the ink, indicating that the ink is more easily supplied to the head portion.

[0030]

[Table 1]

[0031]

[Table 2]

From the above, it can be seen that the ink of the present invention is an ink having good dispersion stability as an ink for ink jet.

Claims (1)

[Claims] 1. An ink jet ink comprising at least a pigment, a dispersant and water, wherein one or more dispersants selected from the group consisting of shellac, humic acid and nitrohumic acid are used in an amount of 0.1 to 2 parts based on the total amount of the ink. 03 parts by weight to 20
Ink jet ink characterized by using parts by weight.