A thermal bubble inkjet printer

Abstract

The present application relates to a thermal bubble inkjet printer, comprising a recording head having a plurality of nozzle rows; ink, including at least black ink, cyan ink, magenta ink, yellow ink; the black ink corresponding black nozzle row and the yellow ink corresponding yellow nozzle row are arranged at the farthest position, and the black nozzle row and the cyan ink corresponding cyan nozzle row are arranged at the adjacent position; the black ink contains self-dispersible pigment, and the cyan ink contains phthalocyanine dye; the static surface tension γ K of the black ink satisfies γ C of the cyan ink satisfies γ K ≤38.0 mN / m; |γ K -γ C |≤4.0 mN / m. The thermal bubble inkjet printer can effectively realize the heat dissipation of the recording head without using a heat sink, and avoid the disorder of the printed image. At the same time, when the black nozzle row and the cyan nozzle row are arranged adjacent to each other, the black nozzle row can be prevented from being blocked, and the jetting stability and printing reliability can be satisfied.

Description

TECHNICAL FIELD

[0001] The present invention relates to a thermal bubble type inkjet printer. BACKGROUND

[0002] An inkjet printer is a device that ejects a color ink liquid through a nozzle to form a fine droplet on a printing paper. In an inkjet printer, ink of four or more colors including yellow, magenta, cyan, and black is usually provided, and a recording head has a nozzle row corresponding to each color of ink. In response to various demands, an inkjet printer having a nozzle row corresponding to each color of ink has been developed, as disclosed in Japanese Patent No. JP6319559B2, "Inkjet Recording Apparatus and Recording Method".

[0003] Various types of inkjet printers have been developed for industrial, commercial, and home use, and particularly home printers are required to be more compact in response to market demands. Many home printers use an integrated recording head having a nozzle array of multiple colors, and a thermal bubble type recording head accumulates heat when performing ink ejection. Therefore, some printers are provided with a heat sink in the recording head to easily release heat, but some printers do not have a heat sink in consideration of compactness and manufacturing cost.

[0004] When a recording head without a heat sink is used to study nozzle arrays of black ink, cyan ink, magenta ink, and yellow ink, it is found that when a black nozzle row and a yellow nozzle row are arranged adjacent to each other, in some cases, a printed image is disordered.

[0005] As a result of further research, the inventors of the present invention have speculated that the occurrence of image disorder is caused by the following reasons. When a color image is continuously printed, black ink and yellow ink are relatively frequently used, but this depends on the type of color image to be output. When a black nozzle row and a yellow nozzle row are arranged adjacent to each other using the above-described thermal bubble type recording head, uneven heat accumulation occurs in the recording head, resulting in a phenomenon of image disorder due to unstable ejection.

[0006] However, based on further research by the applicant, when the black nozzle row and the yellow nozzle row are arranged dispersedly, the above-described image disorder due to unstable ejection is improved, but a new problem of clogging of the black nozzle row occurs. SUMMARY

[0007] The present invention provides a thermal bubble type inkjet printer that effectively releases heat from a recording head even without using a heat sink, avoids heat accumulation, and avoids disorder of a printed image. At the same time, in the case where a black nozzle row and a cyan nozzle row are arranged adjacent to each other, clogging of the black nozzle row is avoided, and the requirements for stable ejection and printing reliability are satisfied.

[0008] The present application solves the above technical problems by employing the technical solution of a thermal bubble inkjet printer comprising

[0009] a recording head having a plurality of nozzle rows for ejecting a plurality of color inks;

[0010] inks supplied to the recording head, including at least black ink, cyan ink, magenta ink, and yellow ink, each color ink corresponding to a matching nozzle row;

[0011] the black nozzle row corresponding to the black ink and the yellow nozzle row corresponding to the yellow ink are arranged at the farthest positions;

[0012] the black ink contains a self-dispersible pigment, and the cyan ink contains phthalocyanine dye;

[0013] the static surface tension γ K of the cyan ink is C satisfying γ K ≤ 38.0 mN / m; |γ K – γ C |≤ 4.0 mN / m.

[0014] Preferably, the self-dispersible pigment includes a functional group bonded to the surface of the pigment particles, and the functional group is a sulfonic acid group or a phosphoric acid group.

[0015] Preferably, the static surface tension γ K of the black ink is ≥ 32.0 mN / m.

[0016] As an improvement, the black ink contains an alcohol amine compound represented by general formula (1);

[0017]

[0018] In formula (1), R1 is any one of groups CH2OH, CH2CH2OH, and H, and R2 is any one of groups CH2OH, CH2CH2OH, and H.

[0019] As an improvement, the black ink contains a polyoxyethylene alkyl ether compound represented by general formula (2);

[0020]

[0021] In formula (2), n is an integer, and 10 ≤ n ≤ 25, and R3 is a linear or branched alkyl group having a carbon atom number in the range of 12-22.

[0022] As an improvement, the black ink contains a water-soluble resin having a non-ionic functional group and an acid value of 100 mgKOH / g or less.

[0023] Compared with the prior art, the advantage of the present application is that in the thermal bubble inkjet printer, the black nozzle row corresponding to black ink and the yellow nozzle row corresponding to yellow ink are arranged at the most distant position in the printing direction, so that even if the heat dissipation layer is not arranged in the recording head, the heat dissipation effect of the black nozzle row and the yellow nozzle row with high use frequency can be improved, heat accumulation is avoided, and the printing image disorder is improved. On this basis, in view of the new problem that the distance between the black nozzle row and the cyan nozzle row corresponding to cyan ink becomes closer, and further causes the black nozzle row to be blocked, the thermal bubble inkjet printer in the present application adjusts the static surface tension of black ink and cyan ink to inhibit the tendency of cyan ink to mix into the nozzle of black ink, thereby inhibiting the nozzle blockage of black ink. DETAILED DESCRIPTION

[0024] In view of the research results proposed in the background art, when the nozzle array of black ink, cyan ink, magenta ink and yellow ink is studied using a recording head without a heat dissipation plate, it is found that when the black nozzle row and the yellow nozzle row are adjacent to each other, in some cases, the printing image will appear disorder.

[0025] The inventors of the present application speculate that the occurrence of image disorder is caused by the following reasons. When continuously printing color images, black ink and yellow ink are relatively frequently used, but this depends on the type of color image to be output. When the black nozzle row and the yellow nozzle row are arranged adjacent to each other using the above-mentioned thermal bubble type recording head, uneven heat accumulation occurs in the recording head, resulting in the phenomenon of image disorder caused by unstable ejection.

[0026] The inventors of the present application have made some technical improvements to the recording head of the thermal bubble inkjet printer based on the analysis of the reasons, specifically, by arranging the black nozzle row corresponding to black ink and the yellow nozzle row corresponding to yellow ink at the most distant position, avoiding heat accumulation during the printing process, the above-mentioned problem is improved, and further, even if the heat dissipation plate is not used in the recording head, the heat dissipation of the recording head can be effectively realized, heat accumulation can be avoided, the printing image disorder can be improved, and the color uniformity of the printing image can be ensured.

[0027] Based on the adjustment of the positions of the black nozzle row and the yellow nozzle row, the black nozzle row and the cyan nozzle row corresponding to cyan ink will be arranged adjacent to each other, and based on this situation, the above-mentioned image disorder caused by unstable ejection is improved when continuously printing color images, but a new problem of blocking of the black nozzle row occurs.

[0028] Based on the analysis of the inventor of the present application, the cause of the clogging of the black nozzle row is that the black ink and the cyan ink are close in properties, and if the cyan ink mixes into the black ink, the self-dispersed pigment in the black ink easily coagulates, causing the nozzle to clog. The self-dispersed pigment of the black ink is carbon black having π conjugation, and the dye molecules contained in the cyan ink also have a phthalocyanine skeleton having π conjugation. From this, the inventor of the present application speculates that the cause of the clogging of the black nozzle row is that the carbon black of the self-dispersed pigment and the phthalocyanine dye interact, and in addition, the drying of the nozzle row causes the coagulation of the self-dispersed pigment. This nozzle row clogging problem does not easily occur in the case of a cyan ink using a triphenylmethane skeleton type dye, which can also be taken as evidence of the above mechanism. In addition, the triphenylmethane skeleton type cyan dye, although excellent in color development, is poor in light resistance and moisture resistance, and thus is not suitable for use alone in an ink formulation for an inkjet printer. The above nozzle clogging problem occurs because the black nozzle row and the yellow nozzle row are arranged at the positions farthest apart from each other in the recording head, causing the black ink in the black nozzle row and the cyan ink in the cyan nozzle row to come close to each other. In addition, the design of arranging the black nozzle row and the yellow nozzle row at the positions farthest apart from each other is not necessary for a piezoelectric inkjet printer or a thermal bubble type inkjet printer having a heat sink. That is, this is a problem that has occurred for the first time in a thermal bubble type inkjet printer that is small in size and has controlled manufacturing costs (does not have a heat dissipation member).

[0029] Based on these, the inventor of the present application found that by adjusting the surface tension of the black ink and the cyan ink, the above nozzle clogging problem can be improved. By controlling the surface tension of the black ink and the cyan ink, the tendency of the cyan ink to mix into the nozzle row of the black ink can be suppressed, and thus the clogging of the black nozzle row can be suppressed.

[0030] The present application will be further described in detail below with reference to the examples.

[0031] A thermal bubble type inkjet printer includes a recording head and a plurality of color inks supplied to the recording head.

[0032] In the present embodiment, the nozzle row corresponding to the black ink is referred to as a black nozzle row, the nozzle row corresponding to the cyan ink is referred to as a cyan nozzle row, the nozzle row corresponding to the magenta ink is referred to as a magenta nozzle row, and the nozzle row corresponding to the yellow ink is referred to as a yellow nozzle row. In addition, in the present embodiment, the letter K is used to represent black, the letter C is used to represent cyan, the letter M is used to represent magenta, and the letter Y is used to represent yellow.

[0033] The black nozzle row corresponding to the black ink and the yellow nozzle row corresponding to the yellow ink are arranged at the positions farthest apart along the moving direction of the recording head. When the black nozzle row and the yellow nozzle row are placed at the positions farthest apart and color images are continuously printed, the position of the nozzle row with high usage rate can be effectively dispersed, and heat accumulation can be avoided, and accordingly, the image disorder phenomenon caused by unstable ejection can be effectively improved even when the recording head without a heat dissipation device is used for printing.

[0034] Based on the adjustment of the positions of the black nozzle row and the yellow nozzle row, the black nozzle row can be arranged adjacent to the cyan nozzle row corresponding to the cyan ink, and the black nozzle row can be blocked. In the embodiment, the problem of the black nozzle row being blocked is solved by adjusting the physical properties of the ink and the components contained in the ink.

[0035] In this way, the heat dissipation of the recording head can be effectively achieved, heat accumulation can be avoided, and image disorder can be avoided. At the same time, when the black nozzle row is arranged adjacent to the cyan nozzle row, the black nozzle row can be prevented from being blocked, and the requirements of stable ejection and reliable printing can be met.

[0036] Hereinafter, the physical properties of the ink and the components contained in the ink in the embodiment will be described in detail.

[0037] I. Physical properties of the ink

[0038] 1.1. Static surface tension

[0039] In the embodiment, the static surface tension of each color ink at 25°C is preferably in the range of 25.0 mN / m to 45.0 mN / m, and more preferably in the range of 30.0 mN / m to 40.0 mN / m.

[0040] In the embodiment, the static surface tension γ K of the black ink and the static surface tension γ C of the cyan ink satisfy γ K ≤ 38.0 mN / m; | γ K – γ C | ≤ 4.0 mN / m. In this way, the nozzle blockage of the black ink can be inhibited. More preferably, γ K ≥ 32.0 mN / m, and γ K < 32.0 mN / m, the color development of the black ink can be low.

[0041] 1.2. Viscosity

[0042] The viscosity of the ink at a temperature of 25°C is preferably in the range of 1.0 mPa-s to 10.0 mPa-s, more preferably in the range of 1.0 mPa-s to 5.0 mPa-s, and particularly preferably in the range of 1.5 mPa-s to 3.5 mPa-s.

[0043] 1.3, pH

[0044] The pH of each color ink in the present embodiment at a temperature of 25°C is preferably in the range of 5.0 to 10.0, and more preferably in the range of 7.0 to 9.5.

[0045] II. Colorant of the ink

[0046] The black ink of the present embodiment contains a self-dispersible pigment, and at least one of the following commercially available products can be used, such as CAB-0-JET 200, CAB-0-JET 300, CAB-0-JET 400, REGAL 250, REGAL 330 manufactured by Cabot Corporation, BONJET BLACK CW-1, BONJET BLACK CW-2, BONJET BLACK CW-3, BONJET BLACK CW-4 manufactured by Oriental Chemical Industries, Ltd., Aqua-Brack manufactured by Tohseiko Co., Ltd., and the like. Particularly preferably, the self-dispersible pigment in the black ink includes a functional group that is bound to the surface of the pigment particles, and the functional group is a sulfonic acid group or a phosphoric acid group. In the case where the functional group of the self-dispersible pigment in the black ink is a sulfonic acid group or a phosphoric acid group, the sulfonic acid group or the phosphoric acid group has a high degree of ionization in an aqueous medium, and thus can be stably dispersed even in the case where aggregation occurs due to the presence of the phthalocyanine dye, thereby solving the problem of clogging of the black nozzle row. In the present embodiment, at least one of REGAL 250, REGAL 330, and CAB-0-JET 400 manufactured by Cabot Corporation is preferably used as the self-dispersible pigment in the black ink.

[0047] In addition, in the present embodiment, the mass ratio of the self-dispersible pigment in the black ink is preferably in the range of 0.5 wt% to 20 wt%, and more preferably in the range of 1 wt% to 10 wt%.

[0048] The phthalocyanine dye used in the cyan ink of the present embodiment only needs to have a phthalocyanine skeleton, and is not particularly limited. The phthalocyanine dye used in the cyan ink can be a direct dye such as C.I. Direct Blue 86, C.I. Direct Blue 199, or the like, or can be a dye described in Japanese Patent No. 4659403 B2, a dye described in Japanese Patent No. 5066079 B2, or the like. These dyes can be used alone or in combination with two or more kinds.

[0049] The magenta ink and the yellow ink preferably contain a dye. The dye is not particularly limited, and at least one of an acid dye, a basic dye, a direct dye, a reactive dye, and the like can be used as needed. Among the various types of dyes, at least one dye of the corresponding type can be specifically selected according to the characteristics required of the ink.

[0050] The direct dye includes C.I. Direct Red 80, C.I. Direct Red 227, C.I. Direct Yellow-12, C.I. Direct Yellow-86, C.I. Direct Yellow-132, and the like.

[0051] The acid dye includes C.I. Acid Red 1, C.I. Acid Red 52, C.I. Acid Red 249, C.I. Acid Red 289, C.I. Acid Yellow 17, C.I. Acid Yellow 23, C.I. Acid Yellow 71, and the like.

[0052] The reactive dye includes C.I. Reactive Red 14, C.I. Reactive Red 141, C.I. Reactive Red 221, C.I. Reactive Yellow 2, C.I. Reactive Yellow 77, C.I. Reactive Yellow 163, and the like.

[0053] These dyes can be used alone or in combination of two or more.

[0054] The mass ratio of the dye in the ink is preferably in the range of 0.5wt% to 20wt%, and more preferably in the range of 1wt% to 10wt%.

[0055] III. Alkanolamine compound

[0056] The ink in the present embodiment preferably contains an alkanolamine compound having a standard boiling point of 250 to 350°C. More preferably, the ink contains an alkanolamine compound represented by general formula (1).

[0057]

[0058] In formula (1), R1 is any one of the groups CH2OH, CH2CH2OH, and H, and R2 is any one of the groups CH2OH, CH2CH2OH, and H.

[0059] The alkanolamine compound represented by general formula (1) is preferably ethanolamine, diethanolamine, or triethanolamine, and more preferably triethanolamine.

[0060] When the above-mentioned alcohol amine compound is contained in the black ink, a particularly excellent effect is obtained. The alcohol amine compound can function as a counter ion of the self-dispersible pigment, and can suppress the aggregation between the self-dispersible pigment and the phthalocyanine dye when the cyan ink is mixed with the black ink.

[0061] The mass ratio of the alcohol amine compound in the ink is preferably in the range of 0.01 to 5.0 wt%, preferably in the range of 0.05 to 3.0 wt%, and more preferably in the range of 0.1 to 1.0 wt% or less.

[0062] IV. Polyoxyethylene alkyl ether compound

[0063] The ink in the present embodiment preferably contains a polyoxyethylene alkyl ether compound represented by the general formula (2).

[0064]

[0065] n in the formula (2) is an integer, and 10 < n < 25, and R3 is a linear or branched alkyl group having 12 to 22 carbon atoms.

[0066] When the above-mentioned polyoxyethylene alkyl ether compound represented by the general formula (2) is contained in the black ink, a particularly excellent effect is obtained. The polyoxyethylene alkyl ether compound represented by the general formula (2) has a polyoxyethylene portion as a hydrophilic portion and an alkyl portion as a hydrophobic portion. The alkyl portion of the hydrophobic portion of the polyoxyethylene alkyl ether compound represented by the general formula (2) is adsorbed to the hydrophobic portion of the self-dispersible pigment, and the polyoxyethylene portion of the hydrophilic portion assists the dispersion stability of the self-dispersible pigment. It is known that a polyoxyethylene chain chelates with a metal ion. The ionic dye containing the phthalocyanine dye is dissolved in water as a salt. When the cyan ink is mixed with the black ink, the aggregation between the self-dispersible pigment and the phthalocyanine dye can be suppressed by chelation of the polyoxyethylene chain with the salt of the phthalocyanine dye.

[0067] The mass ratio of the polyoxyethylene alkyl ether compound represented by the general formula (2) in the ink is in the range of 0.01 to 3.0 wt%, preferably in the range of 0.05 to 2.0 wt%, and more preferably in the range of 0.1 to 1.0 wt%.

[0068] V. Water-soluble resin

[0069] The ink in the present embodiment preferably contains a water-soluble resin having a non-ionic functional group and having an acid value of 100 mgKOH / g or less. The water-soluble resin is preferably at least one of a polyacrylic acid resin, a polyurethane resin, and a polyester resin, and more preferably a polyacrylic acid resin. The polyacrylic acid resin is a polymer of an acrylate, a methacrylate, an acrylonitrile, an acrylic acid, a methacrylic acid, or the like, and the water-soluble resin also includes those obtained by copolymerizing styrene or a styrene derivative with the above-mentioned polymer.

[0070] The acid value of the water-soluble resin contained in the ink in this embodiment is preferably 100 mgKOH / g or less. As the monomer having an acid group having an acid value, acrylic acid, methacrylic acid, styrene sulfonic acid, maleic acid, fumaric acid, itaconic acid, and the like can be used.

[0071] The water-soluble resin contained in the ink in this embodiment preferably contains a water-soluble resin having a nonionic functional group. Examples of the monomer having a nonionic functional group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, ethoxypolyalkylene glycol (meth)acrylate, and the like.

[0072] The acid value of the water-soluble resin is preferably 100 mgKOH / g or less, more preferably 50 mgKOH / g or less.

[0073] The weight average molecular weight of the water-soluble resin is preferably in the range of 1,000 to 50,000, more preferably in the range of 3,000 to 20,000.

[0074] When the above-described water-soluble resin is contained in the black ink, a particularly excellent effect is obtained. The effect is as described above, the water-soluble resin assisting in the dispersion stability of the self-dispersible pigment, and the salt of the phthalocyanine dye being chelated by the polyoxyethylene chain possessed by the water-soluble resin, thereby inhibiting the aggregation of the self-dispersible pigment and the phthalocyanine dye.

[0075] The mass ratio of the water-soluble resin in the ink is in the range of 0.01 wt% to 3.0 wt%, preferably in the range of 0.05 wt% to 2.0 wt%, more preferably in the range of 0.1 wt% to 1.0 wt%.

[0076] VI. Water-soluble Organic Solvent

[0077] The ink of the present embodiment contains a water-soluble organic solvent. Although not particularly limited, examples of the water-soluble organic solvent include at least one of the following.

[0078] Monohydric alcohol: methanol, ethanol, isopropanol, and the like.

[0079] Polyhydric alcohol: ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, trimethylolpropane, glycerol, and the like.

[0080] Polyhydric alcohol ethers: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and the like.

[0081] Glycol diesters: ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, methoxybutyl acetate, and the like.

[0082] Cyclic esters: β-propiolactone, γ-butyrolactone, δ-valerolactone, and the like.

[0083] Nitrogen-containing solvents: urea, ethylene urea, N-methyl-2-pyrrolidone, N-substituted pyrrolidones, and the like.

[0084] As for the ink, the water-soluble organic solvents listed above can be used alone, or at least two of them can be used in combination. The mass ratio of the water-soluble organic solvents in the ink is in the range of 3.0 to 50 wt%, preferably in the range of 5.0 to 40 wt%, and more preferably in the range of 10.0 to 30 wt%.

[0085] Seven, surfactants

[0086] The ink of the present embodiment preferably contains a surfactant. The surfactant can use at least one of anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants. It is particularly preferable to use a nonionic surfactant. The nonionic surfactant includes at least one of alkyl ether surfactants, acetylene glycol surfactants, fluorine surfactants, silicone surfactants.

[0087] The mass percentage content of the surfactant in the ink is 0.01% or more and 3.0 mass%, preferably 0.05% or more and 2.0% or less, and more preferably 0.1% or more and 1.0% or less, based on the total mass of the ink.

[0088] Eight, other ingredients

[0089] The ink can contain a pH adjuster, a mildew-proof agent · preservative, a chelating agent, a rust preventive, a mildew-proof agent, an antioxidant, a reduction inhibitor, a vaporization promoter, and the like.

[0090] The mildew-proof agent, the preservative, Proxel GXL, Proxel XL2, and the like can be used.

[0091] The chelating agent can use ethylenediamine tetraacetate, citrate, and the like.

[0092] Nine, water

[0093] The water contained in the ink in the present embodiment is preferably ion exchange water, pure water, or ultrapure water from which metal ions and the like have been removed.

[0094] Examples

[0095] The hot bubble inkjet printer according to the present application will be described in detail below with reference to specific examples, comparative examples, and reference examples.

[0096] The water-soluble resin in the ink was prepared by using a known radical polymerization method by combining the following monomers: styrene 60 parts, n-butyl acrylate 25 parts, and acrylic acid 15 parts. The acid value of the water-soluble resin 1 was 40 mgKOH / g, and the weight average molecular weight was 10,000.

[0097] The water-soluble resin 2 was prepared by using a known radical polymerization method by combining the following monomers: styrene 35 parts, n-butyl acrylate 30 parts, acrylic acid 5 parts, and methoxy polyethylene glycol acrylate 30 parts (Shin-Nakamura Chemical Co., Ltd.). The acid value of the water-soluble resin 2 was 120 mgKOH / g, and the weight average molecular weight was 9,000.

[0098] In addition, a commercially available water-soluble resin, DISPERBYK 190 (BYK Co., Ltd.), was used in the ink of the present embodiment. The acid value of the DISPERBYK 190 was 10 mgKOH / g, and the weight average molecular weight was 5,000.

[0099] The pigment dispersion 1 in the ink was prepared by putting 20 parts of carbon black, 10 parts of the water-soluble resin 1 neutralized with an aqueous potassium hydroxide solution having the same acid value, and 70 parts of ion-exchanged water into a batch-type vertical sand mill, and dispersing them for 3 hours. Then, the coarse particles were removed by centrifugal separation to prepare the pigment dispersion 1.

[0100] Tables 1-1, 1-2, 1-3, and 1-4 show the inks of the examples, comparative examples, and reference examples. The names of the inks are indicated as A-B, where A is a color code of the ink, and B is a serial number of the ink type, such as K-1, which indicates a black ink No. 1. The components listed in Tables 1-1, 1-2, 1-3, and 1-4 were mixed, and stirred for 30 minutes or more, and then filtered using a 0.2 μm filter. Further, the ink was obtained.

[0101] In addition, the values described in Tables 1-1, 1-2, 1-3, and 1-4 are mass percentages of the effective components. Among them, water is added as a main solvent, and the amount thereof is added to make up the balance to 100 wt%.

[0102] wherein, REGAL 330: manufactured by Cabot; Cab-O-Jet 400: manufactured by Cabot; Cab-O-Jet 300: manufactured by Cabot; DISPERBYK 190: manufactured by BYK; Surfynol 465: manufactured by EVONIK; Proxel GXL: manufactured by LONZA; Polyoxyethylene cetyl ether (n=10): n is the number of repetition of polyoxyethylene chain; Polyoxyethylene cetyl ether (n=20): n is the number of repetition of polyoxyethylene chain; Polyoxyethylene oleyl ether (n=20): n is the number of repetition of polyoxyethylene chain; Polyoxyethylene stearyl ether (n=25): n is the number of repetition of polyoxyethylene chain.

[0103] Table 1-1

[0104]

[0105] Table 1-2

[0106]

[0107] Table 1-3

[0108]

[0109] Table 1-4

[0110] M-1 M-2 M-3 Y-1 Y-2 Y-3 REGAL 330 Cab-O-Jet 400 Cab-O-Jet 300 Pigment Dispersion 1 C.I.Direct Blue 86 C.I.Direct Blue 199 C.I.Acid Blue 9 C.I.Acid Red 249 5 5 5 C.I.Direct Yellow-86 5 5 5 triethanolamine 0.3 0.3 diethanolamine polyoxyethylene cetyl ether (n=10) polyoxyethylene cetyl ether (n=20) 0.2 0.2 0.2 0.2 polyoxyethylene oleyl ether (n=20) polyoxyethylene stearyl ether (n=25) Water-soluble resin 2 0.1 0.1 DISPERBYK 190 trisodium citrate 0.01 0.01 0.01 0.01 0.01 0.01 diethylene glycol 10 10 10 10 10 10 glycerin 10 10 10 10 10 10 Surfynol 465 0.8 0.8 0.8 1 1 1 Proxel GXL 0.1 0.1 0.1 0.1 0.1 0.1 water balance balance balance balance balance balance balance 33.8 33.5 33.5 33.2 33.0 33.1

[0111] Table 2 gives two kinds of thermal bubble recording heads, wherein recording head-1 is not provided with a heat sink, and recording head-2 is provided with a heat sink. Table 3 gives three kinds of recording heads with nozzle row arrangement orders, which are recorded as arrangement-1, arrangement-2, and arrangement-3, respectively.

[0112] Table 2

[0113] static surface tension (mN / m) print head-1 print head-2 mode thermal bubble thermal bubble heat sink none

[0114] Table 3

[0115] yes arrangement-1 K-C-M-Y arrangement-2 K-M-C-Y arrangement-3

[0116] The evaluation of the inks listed in Tables 1-1, 1-2, 1-3 and 1-4 is as follows.

[0117] 1) Inkjet stability

[0118] The inks shown in Tables 1-1, 1-2 and 1-3 were filled into the recording heads shown in Table 2 with four nozzle rows according to the nozzle arrangement orders shown in Table 3, and GB34969 images were printed on 100 sheets of ordinary paper using an inkjet printer. The presence or absence of image disorder was evaluated based on the following criteria.

[0119] Better: Image disturbance never occurs even when printing 100 images.

[0120] Good: Image disturbance occurs when printing over 50 pages.

[0121] Not good: Image disturbance occurs when printing less than 50 pages.

[0122] 2) Recoverability

[0123] The printhead used in the above evaluation of discharge stability is left in an environment of 32°C and 8% RH for 2 weeks. After the leaving, a dot image of 600 dpi in which 4 colors of ink are printed at intervals of 1 dot per A4 size is printed on plain paper. The recoverability is evaluated using the following criteria.

[0124] Better: Ink is discharged from all the nozzles before 50% of printing is completed.

[0125] Good: Ink is discharged from all the nozzles before 100% of printing is completed.

[0126] Not good: There are nozzles from which ink is not discharged even at the end of printing.

[0127] 3) K developability

[0128] Using the recording head evaluated above, a black image is printed, and OD is measured using eXact Basic (manufactured by x-rite), and evaluated using the following criteria.

[0129] Better: OD is 1.0 or more.

[0130] Good: OD is more than 0.9 and less than 1.0.

[0131] Not good: OD is less than 0.9.

[0132] 3) Light resistance

[0133] Using the printhead evaluated above, a cyan image is printed, and left for 2 weeks at a window, and evaluated using eXact Basic (manufactured by x-rite) using the following criteria.

[0134] Good: The residual rate of the OD of the cyan image after the leaving is 90% or more compared to the OD of the cyan image at the initial stage.

[0135] Not good: The residual rate of the OD of the cyan image after the leaving is less than 90% compared to the OD of the cyan image at the initial stage.

[0136] Table 4-1

[0137]

[0138] Table 4-2

[0139]

[0140] Table 4-3

[0141] K-Y-M-C Comparative Example 01 Comparative Example 02 Comparative Example 03 Comparative Example 04 Comparative Example 05 Reference Example 01 print head print head-1 print head-1 print head-1 print head-1 print head-1 print head-1 color arrangement arrangement-1 arrangement-1 arrangement-1 arrangement-1 arrangement-1 arrangement-1 K-15 K-16 K-12 K-12 K-12 K-12 K ink C-5 C-5 C-6 C-7 C-5 C-5 C ink M-3 M-3 M-3 M-3 M-3 M-3 M ink Y-3 Y-3 Y-3 Y-3 Y-3 Y-3 Y ink 39 35.2 35.2 35.2 35.2 35.2 γK 35.3 35.3 31 35.4 35.3 35.3 γC 3.7 0.1 4.2 0.2 0.1 0.1 |γK–γC| inkjet stability good good good good bad better recoverability bad better bad better -- better K color development better bad better better -- better light resistance good good good bad good --

[0142] It should be noted that the ink jet stability, recoverability, K color development, light resistance in Examples 1-16, Comparative Examples 01-05 in Table 4-1, Table 4-2, Table 4-3 are compared with the reference example of Table 4-3. From the results of Table 4-1, 4-2, when the recording head without a heat sink and with color order K-C-M-Y is used to print an image, the ink jet stability can be improved by solving the heat accumulation since the black nozzle row and the yellow nozzle row are located at the farthest position, and can be maintained above the good evaluation standard, but the ink jet stability, recoverability, K color development, light resistance still show differences due to the differences in black ink, cyan ink, composition, and surface tension, as shown in the evaluation results of Examples 13-16, Comparative Examples 01-05.

[0143] For Example 13: Since the ink formula does not contain any of the above alcohol amine compounds, polyoxyethylene alkyl ether compounds or water-soluble resins, the ink jet stability is only good, but since the K color ink uses sulfonic acid-based or phosphoric acid-based pigments, and its static surface tension satisfies γ K ≥ 32.0 mN / m, the recoverability and K color development are better.

[0144] For Example 14: Since the ink formula does not contain any of the above alcohol amine compounds, polyoxyethylene alkyl ether compounds or water-soluble resins, the ink jet stability is only good: at the same time, since the K color ink does not use sulfonic acid-based or phosphoric acid-based pigments, the recoverability is only good; but the static surface tension of the K color ink satisfies γ K ≥ 32.0 mN / m, the K color development is better.

[0145] For Example 15: Since the ink formula does not contain any of the above alcohol amine compounds, polyoxyethylene alkyl ether compounds or water-soluble resins, the ink jet stability is only good, but since the K color ink uses sulfonic acid-based or phosphoric acid-based pigments, the recoverability is better, and since the static surface tension of the K color ink does not satisfy γ K ≥ 32.0 mN / m, the K color development is only good.

[0146] For Example 16: This example adjusts the arrangement order of the nozzle rows relative to Example 13, and the distance between the black nozzle row and the cyan nozzle row is slightly increased, but since none of the above-mentioned alcohol amine compound, polyoxyethylene alkyl ether compound, or water-soluble resin is contained in the ink formulation, the jet stability is only exhibited to a good degree, which is substantially the same as Example 13, and in addition, since the K ink uses a sulfonic acid-based or phosphoric acid-based pigment, and its static surface tension satisfies γ K ≥ 32.0 mN / m, the recoverability and K color development are exhibited to a better degree.

[0147] For Comparative Example 01: Since none of the above-mentioned alcohol amine compound, polyoxyethylene alkyl ether compound, or water-soluble resin is contained in the ink formulation, the jet stability is only exhibited to a good degree, and on this basis, since the static surface tension of the K ink does not satisfy γ K ≤ 38.0 mN / m, the recoverability is exhibited to a poor degree, but since the K ink uses a sulfonic acid-based or phosphoric acid-based pigment, and its static surface tension satisfies γ K ≥ 32.0 mN / m, the K color development is exhibited to a better degree.

[0148] For Comparative Example 02: Since none of the above-mentioned alcohol amine compound, polyoxyethylene alkyl ether compound, or water-soluble resin is contained in the ink formulation, the jet stability is only exhibited to a good degree, but since the K ink uses a non-self-dispersed pigment, there is no problem of aggregation and clogging, but this makes the K color development exhibited to a poor degree.

[0149] For Comparative Example 03: Since none of the above-mentioned alcohol amine compound, polyoxyethylene alkyl ether compound, or water-soluble resin is contained in the ink formulation, the jet stability is only exhibited to a good degree, but since the static surface tensions of the K and C inks do not satisfy |γ K - γ C | ≤ 4.0 mN / m, the recoverability is exhibited to a poor degree, but since the K ink uses a sulfonic acid-based or phosphoric acid-based pigment, and its static surface tension satisfies γ K ≥ 32.0 mN / m, the K color development is exhibited to a better degree.

[0150] For Comparative Example 04: Since none of the above-mentioned alcohol amine compound, polyoxyethylene alkyl ether compound, or water-soluble resin is contained in the ink formulation, the jet stability is only exhibited to a good degree, but since the C ink does not use a copper phthalocyanine-based dye, there is no problem of aggregation and clogging, but this makes the light resistance poor, and since the K ink uses a sulfonic acid-based or phosphoric acid-based pigment, and its static surface tension satisfies γ K ≥ 32.0 mN / m, the K color development is also exhibited to a better degree.

[0151] For Comparative Example 05: Since the nozzle adopts the arrangement-3 mode instead of the arrangement-1, the ink jetting stability shows a poor degree, but because in the arrangement-3 mode, the relative distance between K and C is the farthest, it is difficult to appear the mixed agglomeration blockage condition, since the K color ink uses the sulfonic acid type or phosphoric acid type pigment, and its static surface tension satisfies γ K ≥ 32.0 mN / m, the K color rendering degree shows a better degree.

[0152] In summary, the thermal bubble inkjet printer in the present application arranges the black nozzle row corresponding to the black ink and the yellow nozzle row corresponding to the yellow ink in the recording head at the relatively farthest position along the printing direction, even if the recording head is not provided with a heat dissipation layer, the heat dissipation effect of the black nozzle row and the yellow nozzle row with high use frequency can be improved, heat accumulation is avoided, and the printing image disorder is improved. On this basis, in view of the new problem that the black nozzle row and the cyan nozzle row will be arranged adjacent to each other, and then cause the black nozzle row to be blocked, the thermal bubble inkjet printer in the present application adjusts the static surface tension of the black ink and the cyan ink to inhibit the tendency of the cyan ink to mix into the nozzle of the black ink, and can inhibit the nozzle blockage of the black ink.

Claims

1. A thermal bubble inkjet printer comprising a recording head having a plurality of nozzle rows for ejecting a plurality of color inks; inks supplied to the recording head, including at least black ink, cyan ink, magenta ink, yellow ink, each color ink corresponding to one nozzle row; characterized in that the black ink corresponding black nozzle row and the yellow ink corresponding yellow nozzle row are disposed at the farthest position; the black ink contains a self-dispersible pigment, and the cyan ink contains a phthalocyanine dye; the static surface tension γ of the black ink K the static surface tension γ of the cyan ink C satisfies γ K ≤ 38.0 mN / m; | γ K - γ C | ≤ 4.0 mN / m.

2. The thermal bubble inkjet printer according to claim 1, characterized by: the self-dispersible pigment includes a functional group bound to the surface of the pigment particle, the functional group being a sulfonic acid group or a phosphoric acid group.

3. The thermal bubble inkjet printer according to claim 1 or 2, characterized by: The static surface tension γ of the black ink K ≥ 32.0 mN / m.

4. The inkjet printer according to claim 3, characterized by: the black ink contains an alcohol amine compound represented by general formula (1); in formula (1), R1 is any one of groups CH2OH, CH2CH2OH, H, and R2 is any one of groups CH2OH, CH2CH2OH, H.

5. The inkjet printer according to claim 3, characterized by: the black ink contains a polyoxyethylene alkyl ether compound represented by general formula (2); in formula (2), n is an integer, and 10 ≤ n ≤ 25, and R3 is a linear or branched alkyl group having 12 to 22 carbon atoms.

6. The inkjet printer according to claim 3, characterized by: the black ink contains a water-soluble resin having a nonionic functional group and having an acid value of 100 mgKOH / g or less.

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