Thermal bubble type ink-jet printer

Abstract

The present invention relates to a thermal bubble type inkjet printer, comprising: a recording head having a plurality of nozzle rows for ejecting inks of a plurality of colors, the recording head reciprocating to print an image; the ink is supplied to the recording head and at least comprises black ink, cyan ink, magenta ink and yellow ink, and each color of ink is correspondingly matched with one nozzle row; a black nozzle row corresponding to black ink and a yellow nozzle row corresponding to yellow ink in the recording head are arranged at positions farthest from each other along the moving direction of the recording head; the inks in various colors contain dyes as color materials, and the static surface tension of the yellow ink is the lowest than that of the inks in other colors. According to the thermal bubble type ink-jet printer in the embodiment, even if a heat dissipation plate is not used, heat dissipation of the recording head can be effectively achieved, heat accumulation can be avoided, printed images can be prevented from being disordered, the speed that yellow ink permeates into a printing medium can be higher, and meanwhile the color uniformity of the printed images is guaranteed.

Description

Technical Field

[0001] The invention relates to a thermal bubble inkjet printer. Background Art

[0002] Inkjet printers are used to spray color liquid ink into fine micro-liquids through nozzles onto printing paper. Inkjet printers are usually equipped with four or more colors of ink: yellow, magenta, cyan, and black, and the recording head has a nozzle row corresponding to each ink. In response to various needs, inkjet printers with nozzle rows corresponding to each type of ink have been developed, see the inkjet recording device disclosed in the Japanese invention patent "Inkjet recording device and recording method" with authorization announcement number JP6319559B2.

[0003] Currently, various types of inkjet printers have been developed for industrial, commercial and home use. In particular, home printers are required to be more compact due to market demand. Many home printers use an integrated recording head with a nozzle array of multiple colors. The thermal bubble type recording head accumulates heat when performing inkjet work, so some printers have a heat sink inside the recording head to easily release the heat, but some printers do not have a heat sink from the perspective of compactness and manufacturing cost.

[0004] When nozzle arrays of black ink, cyan ink, magenta ink, and yellow ink were studied using a recording head without a heat sink, it was found that when a black nozzle row and a yellow nozzle row were adjacent to each other, printed images became disordered in some cases.

[0005] As a result of intensive research, the inventors of the present invention presume that the occurrence of image disturbance is caused by the following reasons. When a color image is continuously printed, black ink and yellow ink are used relatively frequently, but this depends on the type of color image to be output. When the black nozzle column and the yellow nozzle column 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 a phenomenon in which image disturbance occurs due to unstable ejection. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a thermal bubble inkjet printer that can effectively dissipate heat from the recording head even without using a heat sink, avoid heat accumulation, avoid disordered printed images, and at the same time ensure color uniformity of the printed images.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: a thermal bubble inkjet printer, comprising

[0008] A recording head having a plurality of nozzle arrays for ejecting inks of a plurality of colors, wherein the recording head reciprocates to print an image;

[0009] Ink is supplied to the recording head, and includes at least black ink, cyan ink, magenta ink, and yellow ink, and each color ink corresponds to a nozzle column;

[0010] The black nozzle column corresponding to the black ink and the yellow nozzle column corresponding to the yellow ink in the recording head are arranged at the farthest positions along the moving direction of the recording head;

[0011] Each color ink contains dye as a color material, and the static surface tension of the yellow ink is the lowest compared to other color inks.

[0012] Preferably, the plurality of nozzle columns in the recording head are arranged in the order of a black nozzle column corresponding to black ink, a cyan nozzle column corresponding to cyan ink, a magenta nozzle column corresponding to magenta ink, and a yellow nozzle column corresponding to yellow ink.

[0013] Preferably, the static surface tension of the black ink is γ Bk , the static surface tension of the cyan ink is γ C , the static surface tension of the magenta ink is γ M , γ Bk , γ C , γ M Satisfies the following relationship: Bk >γ C ; γ Bk >γ M .

[0014] As an improvement, the yellow ink contains an alcoholamine compound represented by general formula (1);

[0015]

[0016] 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.

[0017] As an improvement, the yellow ink contains a polyoxyethylene alkyl ether compound represented by general formula (2);

[0018]

[0019] In formula (2), n is an integer, and 10≤n≤25, and R3 is a straight chain or branched chain alkyl group having 12-22 carbon atoms.

[0020] As an improvement, the yellow ink contains a water-soluble resin having an acid value of less than 100 mgKOH / g and having a non-ionic functional group.

[0021] As an improvement, the yellow ink contains a chelating agent including at least one of ethylenediaminetetraacetate, citrate, phytate and gluconate.

[0022] Compared with the prior art, the advantages of the present invention are: the thermal bubble inkjet printer in the present invention arranges the black nozzle column corresponding to the black ink and the yellow nozzle column corresponding to the yellow ink in the recording head at the farthest relative position along the printing direction. Even if the heat dissipation layer is not provided in the recording head, the heat dissipation effect of the black nozzle column and the yellow nozzle column with high usage frequency can be improved to avoid heat accumulation and thus avoid disordered printed images. In addition, based on the adjustment of ink composition and the limitation of the static surface tension of the yellow ink, the color balance of the printed image can be improved. In this way, the thermal bubble inkjet printer in the present invention can meet the requirements of jetting stability and printing quality at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a four-color superimposed image printed by a recording head using an unoptimized ink composition and a nozzle array arrangement order of Bk, C, M, and Y in an embodiment of the present invention.

[0024] Figure 2 It is a four-color superimposed image printed using a recording head with nozzle arrays arranged in this order: Bk, Y, M, and C. DETAILED DESCRIPTION

[0025] Regarding the research results presented in the background technology: When studying the nozzle arrays of black ink, cyan ink, magenta ink and yellow ink using a recording head without a heat sink, it was found that when the black nozzle row and the yellow nozzle row were adjacent to each other, in some cases, the printed image would become disordered.

[0026] The inventors of the present application presume that the occurrence of image disturbance is caused by the following reasons. When a color image is continuously printed, black ink and yellow ink are used relatively frequently, but this depends on the type of color image to be output. When the black nozzle column and the yellow nozzle column 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 a phenomenon that image disturbance occurs due to unstable ejection.

[0027] Based on the analyzed reasons, the inventor of the present application has made some technical improvements to the recording head of the thermal bubble inkjet printer, thereby improving the aforementioned problem and satisfying the requirement that even if a heat sink is not used in the recording head, the heat dissipation of the recording head can be effectively achieved to avoid heat accumulation, avoid disordered printed images, and at the same time ensure the color uniformity of the printed image.

[0028] The present invention is further described in detail below with reference to the accompanying drawings.

[0029] A thermal inkjet printer includes a recording head and inks of multiple colors supplied to the recording head.

[0030] Among them, the recording head moves back and forth to print the image, and a plurality of nozzle columns for ejecting multiple color inks are distributed along the moving direction of the recording head. The multiple inks supplied to the recording head include at least black ink, cyan ink, magenta ink, and yellow ink. Each color ink corresponds to a nozzle column. For ease of understanding, in this embodiment, the nozzle column corresponding to the black ink is called a black nozzle column, the nozzle column corresponding to the cyan ink is called a cyan nozzle column, the nozzle column corresponding to the magenta ink is called a magenta nozzle column, and the nozzle column corresponding to the yellow ink is called a yellow nozzle column. In addition, in this embodiment, the letter Bk 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.

[0031] The black nozzle row corresponding to the black ink and the yellow nozzle row corresponding to the yellow ink in the recording head are arranged at the farthest positions along the moving direction of the recording head. When the black nozzle row and the yellow nozzle row are placed at the relatively farthest positions and color images are printed continuously, the positions of the nozzle rows with high usage rates can be effectively dispersed to avoid heat accumulation. Accordingly, even when the recording head without a heat dissipation device is printing, the above-mentioned image disorder phenomenon caused by unstable injection can be effectively improved, and a new image quality degradation problem also arises. This is an image quality degradation problem that occurs in the printing method in which the recording head moves back and forth, and the image quality degradation becomes particularly obvious when the black nozzle row and the yellow nozzle row are set at the relatively farthest positions. However, this situation occurs when the black nozzle row and the yellow nozzle row are set adjacent to each other, such as Figure 2 shown, it will not appear.

[0032] In a printing method in which the recording head reciprocates, if the black nozzle row and the yellow nozzle row are placed at the farthest relative positions and an image is formed using the same amount of ink, then Figure 1 As shown, there is a significant difference in brightness between the images formed in the forward direction and in the reverse direction. For example, in the image formed in the forward direction, in the depth direction of the recording medium, a black ink with the lowest brightness is formed on the uppermost surface, and a yellow ink with the highest brightness is formed in the deepest part. In the image formed in the reverse direction, a black ink with the lowest brightness is formed in the deepest part, and a yellow ink with the highest brightness is formed on the uppermost surface. In other words, the two color inks with the largest brightness difference form a coloring material layer that is farthest from each other in the depth direction of the recording medium. Since the coloring material layer with a large brightness difference in the depth direction of the recording medium is printed alternately in the forward direction and the reverse direction on the recording medium, the brightness difference is easily visible, resulting in a significant decrease in image quality.

[0033] This problem of significant degradation of image quality occurs only when the black nozzle row and the yellow nozzle row are arranged at the farthest relative position in the print head. In addition, the piezoelectric inkjet printer and the thermal bubble inkjet printer with a heat sink do not require a design in which the black nozzle row and the yellow nozzle row are arranged at the farthest relative position. In other words, this problem first occurs in a thermal bubble inkjet printer that eliminates the heat sink in order to be compact and reduce manufacturing costs.

[0034] Therefore, in order to improve the image quality problem caused by the setting position of the black nozzle row and the yellow nozzle row, dye is used as the color material in the ink in this embodiment, that is, dye is used as the coloring material contained in the ink, so that the formed coloring material layer is more uniform in the depth direction of the recording medium. In order to further improve the image quality, the static surface tension of the yellow ink with the highest brightness is also controlled in this embodiment. Specifically, the static surface tension of the yellow ink is the lowest compared to other color inks, so that the formed coloring material layer is uniform in the depth direction of the recording medium, thereby improving the image quality. Using dye as a coloring material facilitates the ink to penetrate more easily into the depth direction of the recording medium, and can make the coloring material layer more uniform. At the same time, the static surface tension of the yellow ink with the highest brightness is adjusted to be the lowest compared to other color inks, so that even when the yellow ink becomes the top layer of the recording medium, the yellow ink can penetrate into the recording medium, so that the coloring material layer is formed uniformly.

[0035] Hereinafter, the physical properties of the ink according to the present embodiment and the constituent components contained in the ink will be described.

[0036] 1. Physical properties of ink

[0037] 1.1. Static surface tension

[0038] In this 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.

[0039] The static surface tension of the yellow ink in this example is γ Y Compared to other color inks, the static surface tension of yellow ink is the lowest. As a result, when printing on a recording medium, even if yellow ink is printed as the uppermost layer of the recording medium, yellow ink is most likely to penetrate into the recording medium, so the color material layer formed is more uniform.

[0040] Static surface tension of yellow ink γ Y It is preferably 35.0 mN / m or less.

[0041] It is further preferred that the static surface tension of the black ink is γ Bk , the static surface tension of cyan ink is γC , the static surface tension of magenta ink is γ M , γ Bk , γ C , γ M Satisfies the following relationship: Bk >γ C ; γ Bk >γ M More preferably, γ Bk >γ C ≥γ M >γ Y relationship.

[0042] By setting the static surface tension of the black ink having low brightness to be the highest, the color material layer formed on the recording medium can be made more uniform in both forward and reverse printing.

[0043] 1.2 Viscosity

[0044] In this embodiment, the viscosity of each color 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.

[0045] 1.3 pH

[0046] In this embodiment, the pH value of each color ink 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.

[0047] 2. Coloring materials of ink

[0048] In this embodiment, each color ink contains a dye. According to the needs, at least one of acid dyes, basic dyes, direct dyes, reactive dyes, etc. can be selected for use. Among the various types of dyes, at least one dye of the corresponding type can also be specifically selected according to the requirements for the characteristics of the ink.

[0049] Among them, direct dyes include: CIDirect Black 19, CIDirect Black 51, CIDirect Black 168, CIDirect Blue 1, CIDirect Blue 86, CIDirect Blue 199, CIDirect Red 80, CIDirect Red 227, CIDirect Yellow-12, CIDirect Yellow-86, CIDirect Yellow-132, etc.

[0050] Acid dyes include: CIAcid Black 2, CIAcid Black 52, CIAcid Black 94, CIAcid Blue9, CIAcid Blue 45, CIAcid Blue 254, CIAcid Red 1, CIAcid Red52, CIAcid Red 249, CIAcid Red 289, CIAcid Yellow 17, CIAcid Yellow 23, CIAcid Yellow 71, etc.

[0051] Reactive dyes include: CIReactive Black 19, CIReactive Black 39, CIReactiveBlack 154, CIReactive Red 14, CIReactive Red 141, CIReactive Red 221, CIReactive Blue 2, CIReactive Blue 101, CIReactive Blue 217, CIReactiveYellow 2, CIReactive Yellow77, CIReactive Yellow 163, etc.

[0052] These dyes can be used in the ink alone or in combination of two or more.

[0053] The mass proportion of the dye in the ink is preferably in the range of 0.5 wt % to 20 wt %, more preferably in the range of 1 wt % to 10 wt %.

[0054] 3. Alcoholamine compounds

[0055] The ink in this embodiment preferably contains an alcoholamine compound having a normal boiling point of 250 to 350° C. More preferably, it contains an alcoholamine compound represented by the general formula (1).

[0056]

[0057] 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.

[0058] The alcoholamine compound represented by the general formula (1) is preferably ethanolamine, diethanolamine or triethanolamine, and more preferably triethanolamine.

[0059] When the yellow ink contains an amine compound, a particularly effective effect is shown. The recording medium used for inkjet printing contains many polyvalent metal ions, such as Ca ions and Mg ions. The dye used in the ink has a high water solubility due to the anionic functional group, so when the ink falls on the recording medium, the anionic functional group of the dye may react with the polyvalent metal ions in the recording medium and aggregate. Dye aggregation inhibits the dye from penetrating into the recording medium, thereby inhibiting the uniformity of the coloring material in the recording medium. Since the amine compound has a pH buffering capacity, it can inhibit the reaction between the dye and the polyvalent metal ions and promote the uniformity of the coloring material in the recording medium.

[0060] The mass proportion of the alcoholamine compound in the ink is preferably in the range of 0.01 wt % to 5.0 wt %, preferably in the range of 0.05 wt % to 3.0 wt %, and more preferably in the range of 0.1 wt % to 1.0 wt % or less.

[0061] 4. Polyoxyethylene alkyl ether compounds

[0062] The ink in this embodiment preferably contains a polyoxyethylene alkyl ether compound represented by the general formula (2).

[0063]

[0064] In formula (2), n is an integer, and 10≤n≤25, and R3 is a straight chain or branched chain alkyl group having 12-22 carbon atoms.

[0065] When the yellow ink contains a polyoxyethylene alkyl ether compound represented by the general formula (2), a particularly effective effect is exhibited. As mentioned above, the recording medium used for inkjet printing contains many polyvalent metal ions, such as Ca ions and Mg ions. It is known that the oxyethylene chains of the polyoxyethylene alkyl ether compounds represented by the general formula (2) chelate with the polyvalent metal ions. It is believed that this allows the charge of the polyvalent metal ions to be moderated and the reaction with the dye to be suppressed. Therefore, based on the polyoxyethylene alkyl ether compound represented by the general formula (2) contained in the ink, when the ink lands on the recording medium, the aggregation of the dye and the polyvalent metal ions is suppressed, and the uniformity of the coloring material in the recording medium is promoted.

[0066] The mass proportion of the polyoxyethylene alkyl ether compound represented by the general formula (2) 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%, and more preferably in the range of 0.1 wt% to 1.0 wt%.

[0067] 5. Water-soluble resin

[0068] The ink in this embodiment preferably contains a water-soluble resin having a nonionic functional group and an acid value of less than 100 mgKOH / g. The water-soluble resin is preferably at least one of polyacrylic acid resin, polyurethane resin, and polyester resin, and more preferably polyacrylic acid resin. The polyacrylic acid resin is selected from polymers of acrylate, methacrylate, acrylonitrile, acrylic acid, methacrylic acid, etc., and also includes a resin formed by copolymerization of styrene or styrene derivatives.

[0069] The acid value of the water-soluble resin contained in the ink of this embodiment is preferably 100 mgKOH / g or less. Examples of monomers having an acid group and having an acid value include acrylic acid, methacrylic acid, styrene sulfonic acid, maleic acid, fumaric acid, itaconic acid, and the like.

[0070] The water-soluble resin contained in the ink of the present embodiment preferably contains a water-soluble resin having a nonionic functional group. Examples of monomers having a nonionic functional group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, methoxypolyalkylene glycol (meth)acrylate, and ethoxypolyalkylene glycol (meth)acrylate.

[0071] The acid value of the water-soluble resin is preferably 100 mgKOH / g or less, more preferably 50 mgKOH / g or less.

[0072] 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.

[0073] When the yellow ink contains a water-soluble resin, it is particularly effective. As described above, the effect is to suppress the aggregation of the dye and the polyvalent metal ions when the ink lands on the recording medium and to promote the uniformity of the coloring material on the recording medium.

[0074] The mass proportion 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 %, and more preferably in the range of 0.1 wt % to 1.0 wt %.

[0075] 6. Chelating agents

[0076] The ink in this embodiment preferably contains at least one chelating agent selected from the group consisting of ethylenediaminetetraacetate, citrate, phytate, and gluconate. Preferably, the chelating agent includes ethylenediaminetetraacetate and citrate.

[0077] When the yellow ink contains a chelating agent, it is particularly effective. As described above, its effect is to suppress the aggregation of dyes and polyvalent metal ions when the ink lands on the recording medium and promote the uniformity of the coloring material on the recording medium.

[0078] The mass proportion of the chelating agent in the ink is in the range of 0.001 wt % to 1.0 wt %, preferably in the range of 0.002 wt % to 0.1 wt %, and more preferably in the range of 0.003 wt % to 0.5 wt %.

[0079] 7. Water-soluble organic solvents

[0080] The ink in this 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.

[0081] Monohydric alcohol: methanol, ethanol, isopropanol, etc.

[0082] Polyols: 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, etc.

[0083] Polyol ethers: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, etc.

[0084] Ethylene 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, etc.

[0085] Cyclic esters: β-propiolactone, γ-butyrolactone, δ-valerolactone, etc.

[0086] Nitrogen-containing solvents: urea, ethylene urea, N-methyl-2-pyrrolidone, substituted pyrrolidones, etc.

[0087] 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 proportion of the water-soluble organic solvent in the ink is in the range of 3.0 wt% to 50 wt%, preferably in the range of 5.0 wt% to 40 wt%, and more preferably in the range of 10.0 wt% to 30 wt%.

[0088] 8. Surfactants

[0089] The ink of the present embodiment preferably contains a surfactant. As the surfactant, at least one of anionic surfactants, cationic surfactants, amphoteric surfactants and nonionic surfactants can be used. Nonionic surfactants are particularly preferably used. Examples of nonionic surfactants include at least one of alkyl ether surfactants, acetylene glycol surfactants, fluorine surfactants and silicone surfactants.

[0090] The mass proportion of the surfactant in the ink is in the range of 0.01wt% to 3.0wt%, preferably in the range of 0.05wt% to 2.0wt%, and more preferably in the range of 0.1wt% to 1.0wt%.

[0091] 9. Other ingredients

[0092] The ink may contain other ingredients such as pH adjusters, mildew / corrosion inhibitors, rust inhibitors, antioxidants, reduction inhibitors, drying agents, etc.

[0093] 10. Water

[0094] The water contained in the ink of the present invention is preferably deionized water, pure water, or ultrapure water from which metal ions and the like have been removed.

[0095] Example

[0096] The thermal bubble inkjet printer of the present invention is described in detail below in conjunction with specific embodiments, comparative examples and reference examples.

[0097] The water-soluble resin in the ink was prepared by combining the following monomers using a known free radical polymerization method to prepare water-soluble resin 1: 35 parts of styrene, 30 parts of n-butyl acrylate, 5 parts of acrylic acid, and 30 parts of methoxy polyethylene glycol acrylate (manufactured by Shin-Nakamura Chemical). The acid value of water-soluble resin 1 was 40 mgKOH / g and the weight average molecular weight was 10,000.

[0098] Alternatively, a commercially available water-soluble resin may be used, and DISPERBYK 190 (manufactured by BYK) is used in the ink of this embodiment. DISPERBYK 190 has an acid value of 10 mgKOH / g and a weight average molecular weight of 5,000.

[0099] Tables 1-1, 1-2 and 1-3 show the inks of the embodiments, comparative examples and reference examples. The inks are named AB, where A is the ink color symbol and B is the ink type number, such as Bk-1, which represents black ink No. 1. The components listed in Tables 1-1, 1-2 and 1-3 are mixed, stirred for 30 minutes or longer, and then filtered using a 0.2μm filter to obtain ink. The addition amount of each component material in Tables 1-1, 1-2 and 1-3 is measured by mass fraction.

[0100] Among them, Cab-O-Jet 300K: manufactured by Cabot; Cab-O-Jet 4507C: manufactured by Cabot; Cab-O-Jet4607M: manufactured by Cabot; Cab-O-Jet 4707Y: 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 repetitions of the polyoxyethylene chain; polyoxyethylene cetyl ether (n=20): n is the number of repetitions of the polyoxyethylene chain; polyoxyethylene oleyl ether (n=20): n is the number of repetitions of the polyoxyethylene chain; polyoxyethylene stearyl ether (n=25): n is the number of repetitions of the polyoxyethylene chain.

[0101] Table 1-1

[0102]

[0103] Table 1-2

[0104]

[0105] Table 1-3

[0106] P(Bk-1) P(C-1) P(M-1) P(Y-1) CIDirect Black 168 CIDirect Blue 199 CIAcid Red 249 CIDirect Yellow-86 Cab-O-Jet 300K 5 Cab-O-Jet 4507C 5 Cab-O-Jet 4607M 5 Cab-O-Jet 4707Y 5 Triethanolamine 0.3 0.3 0.3 0.3 Diethanolamine Polyoxyethylene hexadecyl 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 1 DISPERBYK 190 0.1 0.1 0.1 0.1 Disodium EDTA Trisodium Citrate Diethylene glycol 10 10 10 10 glycerin 10 10 10 10 Surfynol 465 0.5 0.7 0.8 0.9 Proxel GXL 0.1 0.1 0.1 0.1 water margin margin margin margin Static surface tension 35.2 34.5 34.1 33.0

[0107] P in Table 1-3 represents pigment ink.

[0108] Table 2 shows two thermal bubble recording heads, where recording head-1 is not provided with a heat sink, and recording head-2 is provided with a heat sink. Table 3 shows three recording heads with nozzle array arrangement sequences, which are respectively recorded as sequence-1, sequence-2, and sequence-3.

[0109] Table 2

[0110] Record Header-1 Record Header-2 type Hot Bubble Hot Bubble Heat sink none have

[0111] Table 3

[0112] Sequence-1 Bk-CMY Sequence-2 Bk-MCY Sequence-3 Bk-YMC

[0113] The inks listed in Tables 1-1, 1-2, and 1-3 were evaluated as follows.

[0114] 1) Ejection stability

[0115] According to the nozzle array arrangement order shown in Table 3, the inks shown in Tables 1-1, 1-2 and 1-3 were filled into the recording head having four nozzle arrays shown in Table 2, and a GB image was printed on 100 sheets of plain paper using an inkjet printer. The presence or absence of the image disorder phenomenon was evaluated based on the following criteria. As the standard image, an image printed according to the conditions in the "Standard" column of Table 4-3 (i.e., black ink is adjacent to yellow ink) was used.

[0116] Better: Print up to 100 images without image distortion.

[0117] Good: When printing 50 pages or more, image disturbance occurs.

[0118] Bad: Less than 50 pages were printed and the image was distorted.

[0119] 2) Image uniformity

[0120] Using the ink and ink cartridge used in the above evaluation, a solid image was printed on plain paper by printing one drop each of black ink, cyan ink, magenta ink, and yellow ink on a 600 dpi grid. The uniformity of the image was evaluated using the following criteria. As a standard image, an image printed according to the conditions in the "Standard" column of Table 4-3 was used.

[0121] Better: Better than the standard image.

[0122] Good: Equivalent to the standard image.

[0123] Bad: Subpar image.

[0124] Table 4-1

[0125]

[0126] Table 4-2

[0127]

[0128] Table 4-3

[0129] Comparative Example 01 Comparative Example 02 Comparative Example 03 Reference Example 01 standard Record Header Record Header-1 Record Header-1 Record Header-1 Record Header-2 Record Header-1 Color Sequence-1 Sequence-1 Sequence-3 Sequence-1 Sequence-3 Bk ink Bk-2 P(Bk-1) Bk-2 Bk-2 Bk-3 C Ink C-2 P(C-1) C-2 C-2 C-3 M Ink M-2 P(M-1) M-2 M-2 M-3 Y Ink Y-13 P(Y-1) Y-2 Y-2 Y-13 Dispensing stability better better not good better -- Image uniformity not good not good better -- --

[0130] It should be noted that the discharge stability and image uniformity in Examples 1-15, Comparative Examples 01-03 and Reference Example 01 in Tables 4-1, 4-2 and 4-3 are all compared with the "Standard" column in Table 4-3 (i.e., black ink is adjacent to yellow ink). From the results of Tables 4-1 and 4-2, when a recording head without a heat sink is used to reciprocate and print an image, if the nozzles of the four colors in the recording head are arranged in the order of sequence 1 and sequence 2 (the black nozzle column and the yellow nozzle column are located at the farthest position), the ink supplied in the recording head is dye ink and the static surface tension of the yellow ink is the lowest, the stability of ink discharge can be effectively guaranteed, that is, the problem of unstable ink ejection and image disorder caused by heat accumulation is solved. On this basis, the uniformity of the brightness of the printed image can also be guaranteed.

[0131] Based on the results of the embodiment, in this embodiment, the multiple nozzle columns in the recording head are preferably arranged in the order of a black nozzle column corresponding to black ink, a cyan nozzle column corresponding to cyan ink, a magenta nozzle column corresponding to magenta ink, and a yellow nozzle column corresponding to yellow ink.

[0132] From the results of Comparative Example 01 in Table 4-3, the static surface tension of yellow ink compared to other color inks will affect the permeability of each color ink in the printer depth direction, thereby affecting the uniformity of the printed image. From the results of Comparative Example 02 in Table 4-3, the type of ink supplied to the recording head will affect the permeability of each color ink in the printer depth direction, thereby affecting the uniformity of the image. From the results of Comparative Example 03 in Table 4-3, in the arrangement order of the nozzle columns of the four colors in the recording head, if the black nozzle column and the yellow nozzle column with high usage frequency are arranged adjacent to each other, it will affect the heat dissipation of the recording head, thereby affecting the ink ejection stability, resulting in a disordered printed image.

[0133] In summary, the thermal bubble inkjet printer of the present invention arranges the black nozzle column corresponding to the black ink and the yellow nozzle column corresponding to the yellow ink in the recording head at the farthest relative position along the printing direction. Even if the heat dissipation layer is not provided in the recording head, the heat dissipation effect of the black nozzle column and the yellow nozzle column with high usage frequency can be improved to avoid heat accumulation and thus avoid disordered printed images. In addition, based on the adjustment of the ink composition and the limitation of the static surface tension of the yellow ink, the color balance of the printed image can be improved. In this way, the thermal bubble inkjet printer of the present invention can meet the requirements of jetting stability and printing quality at the same time.

Claims

1. A thermal inkjet printer, comprising: A recording head having a plurality of nozzle arrays for ejecting inks of a plurality of colors, wherein the recording head reciprocates to print an image; Ink is supplied to the recording head, and includes at least black ink, cyan ink, magenta ink, and yellow ink, and each color ink corresponds to a nozzle column; Features: The black nozzle column corresponding to the black ink and the yellow nozzle column corresponding to the yellow ink in the recording head are arranged at the farthest positions along the moving direction of the recording head; Each color ink contains dye as a color material, and the static surface tension of the yellow ink is the lowest compared to other color inks.

2. The thermal bubble inkjet printer according to claim 1, characterized in that: The plurality of nozzle columns in the recording head are arranged in the order of a black nozzle column corresponding to black ink, a cyan nozzle column corresponding to cyan ink, a magenta nozzle column corresponding to magenta ink, and a yellow nozzle column corresponding to yellow ink.

3. The thermal bubble inkjet printer according to claim 1 or 2, characterized in that: The static surface tension of the black ink is γ Bk , the static surface tension of the cyan ink is γ C , the static surface tension of the magenta ink is γ M , γ Bk , γ C , γ M Satisfies the following relationship: Bk >γ C ; γ Bk >γ M .

4. The thermal bubble inkjet printer according to claim 3, characterized in that: The yellow ink contains an alcoholamine compound represented by general formula (1); 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.

5. The thermal bubble inkjet printer according to claim 3, characterized in that: The yellow 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 straight chain or branched chain alkyl group having 12-22 carbon atoms.

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

7. The thermal bubble inkjet printer according to claim 3, characterized in that: The yellow ink contains at least one chelating agent selected from the group consisting of ethylenediaminetetraacetate, citrate, phytate and gluconate.

Images