JP2903631B2 - Ink for inkjet printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink used in an ink jet recording apparatus that forms characters and images on a medium such as recording paper by flying ink droplets.

[Prior Art] Conventionally, ink jet recording methods can be broadly classified into two types, a continuous type and an on-demand type. As an ink used in such an ink jet system, an ink in which a dye is dissolved in water is dominant.

As the aqueous ink, those obtained by dissolving various water-soluble dyes in water or a solvent composed of water and a water-soluble organic solvent and adding various additives as necessary are currently used. The advantages of these inkjet recording methods are that the process is simple because of direct recording, that there is no noise because it is not an impact method, that colorization is easy, that high-speed recording is possible, and that small ink droplets are ejected. It has excellent features such as high-resolution recording and the like, and its future potential is attracting attention.

[Problems to be Solved by the Invention] However, in the above-mentioned prior art, although slightly different depending on the method, ink jet recording generally uses an aqueous ink, but the aqueous ink has a low boiling point of water and a saturated vapor pressure. Therefore, clogging due to ink drying in the nozzle portion is likely to occur. Recently, various inks for ink jet printers in which various pigments are dispersed in various liquids have been reported, but problems such as dispersion stability of dispersed pigment particles and clogging of nozzle portions have not been solved.

Therefore, the present invention has been made to solve these problems, and an object of the present invention is to provide an ink jet printer ink used for an ink jet recording system, which does not cause nozzle clogging or the like at a nozzle portion and has excellent pigment dispersion stability. To provide an ink for an ink jet printer.

[Means for Solving the Problems] The ink for an ink jet printer of the present invention is an ink for an ink jet printer containing at least a pigment, a resin, a non-polar insulating solvent and a dispersant. And a coupling agent for coupling.

[Operation] The operation of the ink for an inkjet printer of the present invention will be described. FIG. 1 shows a conceptual diagram of the ink for an ink jet printer of the present invention. 11 is pigment particles, 12 is a resin or dispersant molecule, 13 is a coupling agent, and 14 is a non-polar insulating solvent. Since the resin or dispersant 12 in the ink for an ink jet printer of the present invention is completely soluble in the solvent 14, it is uniformly present in the solvent 14. In such a system, a pigment 11 that has been subjected to a coupling reaction with a resin or dispersant 12 that is uniformly dissolved in a solvent 14 using a coupling agent 13 with a coupling agent 13 is treated with DLVO by ordinary activator treatment, resin adsorption treatment, and surface treatment. Dispersion stability is maintained by a principle different from the dispersion stability due to electric force or osmotic pressure effect / entropy effect as shown in theory. That is, as shown in FIG. 1, sedimentation and aggregation do not occur at all by adopting a matrix structure held in a solvent.

[Examples] Hereinafter, the present invention will be described specifically with reference to Examples.
It is not limited to this.

The method for producing the ink for an ink jet printer of the present invention was performed as follows. A predetermined amount of the resin is dissolved in an insulating solvent which is a dispersion medium. To this resin solution, a coupling agent that causes a chemical bonding reaction with a functional group in the dissolved resin molecule was gradually added. Solution at 50 ° C when adding coupling agent
After the addition of the coupling agent, the reaction was continued for 2 hours while maintaining the temperature at 50 ° C. At this time, a catalyst may be added for the purpose of promoting the chemical reaction between the resin and the coupling agent. Check that the chemical reaction between the resin and the coupling agent has been completed.
After confirming using FT-IR, the solution was transferred to an attritor, and the pigment was added in a specified amount, dispersed for 12 hours, and a chemical bond was formed between the coupling agent and the pigment. To give a homogeneous dispersion. Thereafter, by-products generated by a chemical bond between the silane coupling agent and the pigment or the resin are removed. After adding and dissolving a dispersant as needed, the ink for an inkjet printer of the present invention can be obtained by filtering with a filter or the like in order to remove giant particles, dust and the like. In the case where the dispersant is subjected to a coupling reaction with the pigment, in the above-described ink production method, after the reaction between the dispersant and the coupling agent is first performed, by-products generated by the reaction are removed. The ink for an inkjet printer of the present invention can be obtained by dissolving the resin in this solution in a predetermined addition amount, and further causing the pigment to chemically react and disperse with the coupling agent.

Needless to say, the coupling reaction step is not limited to this.

As the physical properties of the ink-jet ink adjusted by the above-described ink manufacturing method, the ink viscosity when the temperature during operation is set to 0 to 50 ° C. indicates the ink supply stability and the ink drop under the high-speed response of the head. 20mPa · s or less is required in the vicinity of the nozzle at the time of ejection due to the formation flight stability, and 2.0 to 15.0mPa is required to achieve even faster response.
・ S is more preferred.

 The components of the ink are specifically illustrated below.

As the pigment, various organic or waste pigments including conventionally known pigments can be used. Examples include carbon black, insoluble azo pigments, soluble azo pigments, phthalocyanine pigments, isoindolinone luxury pigments, quinacridone luxury pigments, perinone / perylene luxury pigments, etc., anthraquinone pigments, dioxazine pigments, and isidigo pigments. Pigments, thioindigo pigments, metal oxides (iron oxide, titanium oxide, cadmium oxide, chromium oxide, etc.) and the like can be mentioned. In addition, a processed pigment whose particle surface is coated with a resin or the like can be used. These may be used in combination of two or more in some cases.

As the resin, specifically, ethyl cellulose, polyacrylester, linseed oil-modified alkyd resin, polyvinyl chloride, chlorinated polypropylene, polyamide resin,
Coumarone indene resin, rosin resin, terpene phenol resin, alkylphenol-modified xylene resin, maleic anhydride resin, isoprene resin, styrene resin,
Ethylene-methacrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer,
And the like are preferable, and those soluble in a solvent are preferable from the viewpoint of ink storability. Furthermore, from the viewpoint of blocking of the recorded matter after printing, the melting point or softening point of the resin is
50 ° C. or higher is preferred. These may be used in combination of two or more in some cases. The resin that can be used as the resin component of the present invention is not limited to this, and any resin capable of causing a coupling reaction with a pigment can be used in the present invention.

Solvents include aliphatic hydrocarbon solvents, specifically Exxon Chemical's Isopar, Philippe Petroleum's Soltor, Idemitsu Petrochemical's IP Solvent, and Petroleum Naphtha at Shell Petrochemical's Shell SBR, Shell Sol, and Mobil. Petroleum Corporation's Vegazol, etc. The properties required for the insulating solvent are low toxicity, low flammability,
Low odor. These may be used as a mixture of two or more kinds in some cases.

Further, the dispersant or the dispersant that can be coupled with the pigment, which is added as necessary, may be any as long as it is compatible with the solvent or can stably provide fine particle dispersion and dispersion stability. Sorbitan fatty acid esters (sorbitan monooleate, sorbitan monolaurate, sorbitan sesquioleate, sorbitan trioleate, etc.), polyoxyethylene sorbitan fatty acid esters (polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, etc.) ), Polyethylene glycol fatty acid esters (polyoxyethylene monostearate, polyethylene glycol diisostearate, etc.), polyoxyethylene alkyl phenyl ether (polyoxyethylene nonyl phenyl ether) Polyoxyethylene octylphenyl ether) nonionic active agents such as are suitable.
Further, in addition to the nonionic activator, an activator (dispersant) generally known as an anionic activator or a cationic activator can be used in the present invention. These dispersants can be used as a mixture of two or more kinds in some cases. Further, other than the above-mentioned dispersants, any dispersant that causes a coupling reaction with a pigment can be used in the present invention.

In the case of an organic titanium-based coupling agent, examples of the coupling agent include tetraisopropyl titanate, tetrabutyl titanate, tetrastearyl titanate, and isopropoxy titanium stearate titanium lactate. Examples of the chromium-based coupling agent include Volan manufactured by Du Pont and Valchrome 5015 manufactured by Valchem. As the silyl peroxide-based coupling agent, those represented by the following structural formula can be considered.

Further, an organic phosphoric acid-based coupling agent can be represented by the following structural formula.

As organic silane coupling agents, vinyl trichlorosilane, vinyl tris (β-methoxyethoxy)
Silane, vinyltriethoxysilane, vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxy Propylmethyldiethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ- Examples thereof include aminopropyltrimethoxysilane, γ-mercaptoptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, and the like.

The coupling agent of the present invention is not limited to the examples described above, and any coupling agent can be used as long as it shows a coupling reaction with the pigment, the resin in the ink and the dispersant.

(Examples) Inks were produced by adjusting the compositions shown in the following Examples 1 to 16. The manufactured ink was subjected to bit image printing, character printing, etc. on various types of transferred objects such as general high-quality paper, bond paper, PPC paper, and OHP sheets by an ink jet recording apparatus, and then a1 to a5 were evaluated. .

(A1) Print bleeding property: After printing on various types of transfer objects, the presence or absence of ink bleeding is evaluated by visual or microscopic observation. No bleeding is observed in the print by visual or microscopic observation. ◎) · Bleeding of the print was observed by microscopic observation ··· Appropriate (○) · Bleeding of the print was visually observed · · · Unsuitable (X).

(A2) Print abrasion resistance: After printing on the object to be transferred by handshake, the presence or absence of stains caused by rubbing the printed surface with a load of 200 kg / cm2 with a clip is evaluated by the number of times of rubbing. Above no occurrence after friction ··· Suitable (◎) · Occurrence after friction of 20 to 30 reciprocations · · Appropriate (○) · Occurrence after friction of less than 20 reciprocations · Unsuitable (X).

(A3) Drying speed of printed matter: Solid printing is performed on a non-transfer medium of A4 size, rubbed lightly with the fingertip, and depending on the time until ink does not adhere to the fingertip, within 10 seconds… preferred (◎) ・10 seconds or more and less than 30 seconds… suitable (○) ・ 30 seconds or more… unsuitable (×)

(A4) Nozzle clogging: Fill the ink jet recording device with ink, leave it in a 50 ° C environment without a cap on the nozzle for one month, evaluate the ink discharge status, and discharge immediately. ◎) ・ Evaluated and classified by rubbing with a little or with a rubber plate ... appropriate (○) ・ Not discharging ・ ・ ・ unsuitable (×)

(A5) Ink dispersion stability: Immediately after the production of the ink, the pigment particles were produced at an average particle diameter of 1 micron, and were placed in a 70 ° C. constant temperature bath.
The dispersion stability was evaluated based on the average particle size of the pigment particles after standing for a month. ・ 2 μm or less ・ ・ ・ preferred (◎) ・ 2-5 μm ・ ・ ・ suitable (○) ・ 5 μm or more ・ ・ ・ unsuitable ( ×) Classification was performed. In addition, since the commercially available inks for ink jet printers of Comparative Examples 1 and 2 were dye-dissolved inks, this evaluation was not performed.

 Table 1 shows the results.

Comparative Example Similarly, inks for an ink jet printer shown on pages 28 to 29 were produced as comparative examples 1 and 3, and a commercial water-based ink was evaluated as comparative example 2. The evaluation was performed in the same manner as in Examples of the present invention, and the results are shown in Table 1. In Comparative Example 3, the ink and the composition for an ink jet printer according to the present invention are almost the same, and the pigment and the resin or the dispersant are not subjected to the coupling treatment.

As is clear from Table 1, the inks for ink jet printers of the present invention show good results in all evaluations. In particular, Comparative Example 3 previously invented by the inventor of the present invention
As compared with the above, the ink dispersion stability of the present invention showed excellent results.

(Example 1) Pigment Aniline black (Sanyo dye) 10.0% Solvent Isopar L (Exxon Chemical) 73.8% Resin Aromatic oligomer (Mitsubishi Petroleum) 15.0% Dispersant Polyoxyethylene sorbitan monooleate (Nikko Chemicals) 0.2% Coupling Agent (to resin) Tetraisopropyl titanate 1.0% (Example 2) Pigment Aniline black (Sanyo Dye) 10.0% Solvent IP1620 (Idemitsu Petrochemical) 73.8% Resin Hydrogenated terpene (Yasuhara Chemical) 15.0% Dispersant Polyoxyethylene sorbitan mono Oleate (Nikko Chemicals) 0.2% Coupling agent (to resin) Voan (Du Pont) 1.0% (Example 3) Pigment Carbon black Printex55 (Degussa) 10.0% Solvent Isopar L (Exxon Chemical) 74.0% Resin 1.3 Pentadiene resin (Nippon Zeon) 15.0% Coupling agent (to resin) Dimethoxya Lil tertiary butyl peroxide silane 1.0% (Example 4) Pigment carbon black Printex55 (Degussa) 10.0% Solvent IP1620 (Idemitsu Petrochemical) 73.8% Resin Special rosin ester (Arakawa Chemical) 15.0% Dispersant Polyoxyethylene sorbitan monoole Eat (Nikko Chemicals) 0.2% Coupling agent (vs. resin) Dimethoxyhydroxyphosphine 1.0% (Example 5) Pigment Iron oxide EPT-1000 (Toda Kogyo) 10.0% Solvent Isopar L (Exxon Chemical) 73.8% Resin Specialty rosin Ester (Arakawa Chemical) 15.0% Dispersant Sorbitan monooleate (Nikko Chemicals) 0.2% Coupling agent (to dispersant) Vinyltrichlorosilane 1.0% (Example 6) Pigment Iron oxide EPT-1000 (Toda Kogyo) 10.0% Solvent IP1620 (Idemitsu Petrochemical) 73.8% Resin Terpene-modified phenolic resin (Yasuhara Chemical) 15.0 Dispersant Polyoxyethylene sorbitan monooleate (Nikko Chemicals) 0.2% Coupling agent (to resin) β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane 1.0% (Example 7) Pigment Aniline Black (Sanyo Dye) 10.0 % Solvent Isopar L (Exxon Chemical) 73.8% Resin Hydrogenated terpene (Yasuhara Chemical) 15.0% Dispersant Polyoxyethylene sorbitan monooleate (Nikko Chemicals) 0.2% Coupling agent (to resin) β- (3,4 epoxycyclohexyl) ) Ethyltrimethoxysilane 1.0% (Example 8) Pigment carbon black Printex55 (Degussa) 10.0% Solvent IP1620 (Idemitsu Petrochemical) 74.0% Resin Hydrogenated terpene (Yasuhara Chemical) 15.0% Coupling agent (to resin) β- ( 3,4 epoxycyclohexyl) ethyltrimethoxysilane 1.0% Example 9) Pigment Iron oxide EPT-1000 (Toda Kogyo) 10.0% Solvent Isopar L (Exxon Chemical) 73.8% Resin 1.3 Pentadiene resin (Nippon Zeon) 15.0% Dispersant Polyoxyethylene sorbitan monooleate (Nikko Chemicals) 0.2 % Coupling agent (vs. dispersant) Vinyl trichlorosilane 1.0% (Example 10) Pigment carbon black Printex55 (Degussa) 10.0% Solvent IP1620 (Idemitsu Petrochemical) 73.8% Resin Special rosin ester (Arakawa Chemical) 15.0% Dispersant Sorbitan Monooleate (Nikko Chemicals) 0.2% Coupling agent (to dispersant) β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane 1.0% (Example 11) Pigment Quinacridone Magenta (Dainippon Ink) 10.0% Solvent Isopar L (Exxon Chemical) 73.8% Resin Aromatic oligomer (Mitsubishi Oil) 15.0% dispersion Materials Sorbitan monolaurate (Sanyo Chemical) 0.2% Coupling agent (to resin) Vinyl trichlorosilane 1.0% (Example 12) Pigment Quinacridone magenta (Dainippon Ink) 10. Solvent IP1620 (Idemitsu Petrochemical) 73.8% Resin Terpene modified Phenol resin (Yasuhara Chemical) 15.0% Dispersant Polyoxyethylene nonyl phenyl ether (Kao) 0.2% Coupling agent (to resin) γ-aminopropyltriethoxysilane 1.0% (Example 13) Pigment Copper phthalocyanine (ICI) 10.0% Solvent Isopar L (Exxon Chemical) 73.8% Resin Special rosin ester (Arakawa Chemical) 15.0% Dispersant Polyoxyethylene alkyl ether (Sanyo Chemical) 0.2% Coupling agent (to dispersant) γ-aminopropyltriethoxysilane 1.0% (Examples) 14) Pigment Copper phthalocyanine (ICI) 10.0% Solvent Isopar L (Exxon Chemical) 73.8% Resin 1.3 Pentadiene resin (Nippon Zeon) 15.0% Dispersant Polyoxyethylene alkyl ether (Sanyo Chemical) 0.2% Coupling agent (to dispersant) γ-mercaptopropyltrimethoxysilane 1.0% (Example 15) Pigment India Yellow (Ciba Geigy) 10.0% Solvent Isopar L (Exxon Chemical) 73.8% Resin Hydrogenated terpene (Yasuhara Chemical) 15.0% Dispersant Polyoxyethylene nonyl phenyl ether (Kao) 0.2% Coupling agent (for dispersant) β -(3,4 epoxycyclohexyl) ethyltrimethoxysilane 1.0% (Example 16) Pigment Indian Yellow (Ciba Geigy) 10.0% Solvent Isopar L (Exxon Chemical) 73.8% Resin Aromatic oligomer (Mitsubishi Oil) 15.0% Dispersant Sorbitan Mono Laurate (Sanyo Chemical) 0.2% coupling (Resin) β- (3,4 epoxycyclohexyl) ethyltrimethoxysilane 1.0% (Comparative Example 1) Dye Sudan Black X-60 (BASF) 5.0% Solvent Isopar L (Exxon Chemical) 85.0% Resin Aromatic oligomer (Mitsubishi) Petroleum) 10.0% (Comparative Example 2) Commercial aqueous ink (Comparative Example 3) Pigment Aniline Black (Sanyo Pigment) 10.0% Solvent Isopar L (Exxon Chemical) 74.8% Resin Aromatic oligomer (Mitsubishi Oil) 15.0% Dispersant Polyoxyethylene Sorbitan monooleate (Nikko Chemicals) 0.2% [Effects of the Invention] As described above, the use of the ink for an ink jet printer of the present invention includes a coupling agent for coupling a resin or a dispersing agent with a pigment, so that the nozzle portion which has conventionally been problematic The ink storability as a dispersion ink was improved to a high level that could not be realized until now.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the ink for an ink jet printer of the present invention. 11: Pigment 12: Resin or dispersant 13: Coupling agent

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yaeko Maruyama 3-3-5 Yamato, Suwa-shi, Nagano Seiko Epson Corporation (58) Field surveyed (Int. Cl. ⁶ , DB name) C09D 11 / 00-11/14

Claims (1)

(57) [Claims] 1. An ink jet printer ink comprising at least a pigment, a resin, a non-polar insulating solvent, and a dispersant, wherein the ink contains a coupling agent for coupling the pigment with the resin or the dispersant. Ink for inkjet printers.