Thermal bubble type ink-jet printer

Abstract

A thermal bubble inkjet printer includes a recording head having a plurality of nozzle rows; the ink at least comprises black ink, cyan ink, magenta ink and yellow ink; the black nozzle row corresponding to the black ink and the yellow nozzle row corresponding to the yellow ink are arranged at a farthest position, and the black nozzle row and the cyan nozzle row corresponding to the cyan ink are arranged at adjacent positions. The black ink contains a self-dispersing pigment, and the cyan ink contains a phthalocyanine dye; the static surface tension gamma K of the black ink and the static surface tension gamma C of the cyan ink meet the condition that gamma K is less than or equal to 38.0 mN / m; gamma K-gamma C < = 4.0 mN / m. According to the thermal bubble type ink-jet printer, even if a heat dissipation plate is not used, heat dissipation of the recording head can be effectively achieved, and printed images are prevented from being disordered. Meanwhile, when the black nozzle row and the cyan nozzle row are adjacently arranged, the black nozzle row can be prevented from being blocked, and the spraying stability and the printing reliability are met.

Description

Technical Field

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

[0002] Inkjet printers are printers that spray colored ink liquid into tiny droplets through nozzles onto printing paper. Inkjet printers are usually equipped with four or more colors of ink, including yellow, magenta, cyan, and black, and the recording head has a nozzle column corresponding to each color ink. In response to various needs, inkjet printers with nozzle columns corresponding to each color 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 column and a yellow nozzle column 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.

[0006] However, based on further research by the applicant, when the black nozzle array and the yellow nozzle array are dispersedly arranged, the image disturbance caused by the above-mentioned ejection instability is improved, but a new problem of clogging of the black nozzle array arises. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a thermal bubble inkjet printer for the above-mentioned prior art, which can effectively achieve heat dissipation of the recording head even without using a heat sink, avoid heat accumulation, and avoid disordered printed images. At the same time, when the black nozzle column and the cyan nozzle column are arranged adjacent to each other, the black nozzle column can be prevented from being blocked, and the requirements of jetting stability and printing reliability can be met at the same time.

[0008] The technical solution adopted by the present invention to solve the above technical problems is: a thermal bubble inkjet printer, comprising

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

[0010] 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;

[0011] The black nozzle column corresponding to the black ink and the yellow nozzle column corresponding to the yellow ink are arranged at positions farthest apart from each other;

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

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

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

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

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

[0017]

[0018] In formula (1), R1 is a CH group 2 OH, CH 2 CH 2 Any of OH, H, R2 is a CH group 2 OH, CH 2 CH 2 Any one of OH 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 straight chain or branched chain alkyl group having 12-22 carbon atoms.

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

[0023] 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, thereby improving the disorder of the printed image. On this basis, in view of the new problem that the distance between the black nozzle column and the cyan nozzle column will become closer, thereby causing the black nozzle column to be blocked, the thermal bubble inkjet printer in the present invention suppresses the tendency of the cyan ink to mix into the nozzle at the black ink by adjusting the static surface tension of the black ink and the cyan ink, thereby suppressing the clogging of the black ink nozzle. DETAILED DESCRIPTION

[0024] 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 column and the yellow nozzle column are adjacent to each other, in some cases, the printed image will become disordered.

[0025] 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.

[0026] The inventor of the present invention application has made some technical improvements to the recording head of the thermal inkjet printer based on the analyzed reasons. Specifically, the above-mentioned problem is improved by configuring the black nozzle column corresponding to the black ink and the yellow nozzle column corresponding to the yellow ink at the farthest positions to avoid heat accumulation in the printing process. Therefore, 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, improve the disorder of the printed image, and at the same time ensure the color uniformity of the printed image.

[0027] Based on the adjustment of the positions of the black nozzle column and the yellow nozzle column, the black nozzle column will be set adjacent to the cyan nozzle column corresponding to the cyan ink. Based on this situation, when the color image is printed continuously, the image disorder caused by unstable ejection is improved, but a new problem of clogging of the black nozzle column arises.

[0028] Based on the analysis of the inventor of the present invention, the black nozzle column is blocked because the properties of black ink and cyan ink are similar. If cyan ink is mixed into the nozzle of black ink, the self-dispersible pigment in the black ink is easy to condense and the nozzle is blocked. The self-dispersible pigment of black ink is carbon black with π conjugation, and the dye molecules contained in cyan ink also have π conjugated phthalocyanine skeletons. Therefore, the inventor of the present invention speculates that the problem of the black nozzle column being blocked is that the carbon black and phthalocyanine dye of the self-dispersible pigment interact with each other, and the drying of the nozzle column causes the aggregation of the self-dispersible pigment. This nozzle column blocking problem is not easy to occur when using cyan ink with triphenylmethane skeleton dye, which can also serve as evidence of the above mechanism. In addition, although the triphenylmethane skeleton cyan dye has excellent color development, it has poor light resistance and moisture resistance, and is therefore not suitable for ink preparation for inkjet printers alone. The above-mentioned nozzle blocking problem occurs because the black nozzle column and the yellow nozzle column in the recording head are arranged at the farthest relative distance, so that the black ink in the black nozzle column and the cyan ink in the cyan nozzle column are close to each other. In addition, the design of arranging the black nozzle row and the yellow nozzle row at the farthest relative position is not necessary for a piezoelectric inkjet printer or a thermal bubble inkjet printer with a heat sink. In other words, this is a problem that first occurs in a thermal bubble inkjet printer that is compact and has a low manufacturing cost (no heat sink is provided).

[0029] On these foundations, the inventors of the present invention have found that the above-mentioned nozzle clogging problem can be improved by adjusting the static surface tension of black ink and cyan ink. By controlling the static surface tension of black ink and cyan ink, the tendency of cyan ink to mix into the nozzle column at the black ink can be suppressed, thereby suppressing the clogging of the black nozzle column.

[0030] The present invention is further described in detail below with reference to the embodiments.

[0031] A thermal inkjet printer includes a recording head and inks of multiple colors supplied to the recording head.

[0032] Among them, 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 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 array corresponding to the black ink and the yellow nozzle array 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 array and the yellow nozzle array are placed at the farthest positions and a color image is printed continuously, the positions of the nozzle arrays 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 ejection can be effectively improved.

[0034] Based on the adjustment of the positions of the black nozzle column and the yellow nozzle column, the black nozzle column and the cyan nozzle column corresponding to the cyan ink may be arranged adjacent to each other, which may lead to the problem of clogging of the black nozzle column. In this embodiment, the problem of clogging of the black nozzle column 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 realized, heat accumulation can be avoided, and the printed image can be prevented from being disturbed. At the same time, when the black nozzle column and the cyan nozzle column are arranged adjacently, the blockage of the black nozzle column can be avoided, and the requirements of jetting stability and printing reliability can be met at the same time.

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

[0037] 1. Physical properties of ink

[0038] 1.1. Static surface tension

[0039] 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.

[0040] The static surface tension of the black ink in this embodiment is γ K and the static surface tension of cyan ink γ C Satisfaction K ≤38.0mN / m;|γ K – γ C |≤4.0mN / m. Thus, clogging of the nozzle of black ink can be suppressed. More preferably, γ K ≥32.0mN / m, γ K When the value is less than 32.0 mN / m, the color rendering property of black ink may decrease.

[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] 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.

[0045] 2. Coloring materials of ink

[0046] The black ink of this embodiment contains a self-dispersible pigment, and specifically at least one of the following commercially available products can be used, such as CAB-0-JET200, CAB-0-JET300, CAB-0-JET400, REGAL250, REGAL330 manufactured by Cabot Corporation, BONJET BLACK CW-1, BONJET BLACK CW-2, BONJET BLACK CW-3, BONJET BLACK CW-4 manufactured by Oriental Chemical Corporation, Aqua-Brack manufactured by Donghai Carbon Corporation, etc. Particularly preferably, the self-dispersible pigment in the black ink includes a functional group bonded to the surface of the pigment particle, and the functional group is a sulfonic acid group or a phosphoric acid group. In view of the problem that the aggregation of self-dispersible pigment and phthalocyanine dye may cause the blockage of black nozzle column, when the functional group of the self-dispersible pigment in the black ink is sulfonic acid group or phosphoric acid group, the sulfonic acid group and phosphoric acid group have high ionization degree in the water-soluble medium, so even in the case of aggregation due to the presence of phthalocyanine dye, it can be stably dispersed, thereby solving the problem of blockage of black nozzle column. In this embodiment, the self-dispersible pigment in the black ink is preferably at least one of REGAL250, REGAL330, and CAB-0-JET400 manufactured by Cabot Corporation.

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

[0048] The cyan ink in this embodiment contains phthalocyanine dyes, and the dyes only need to have a phthalocyanine skeleton, and there are no other special restrictions. The phthalocyanine dyes in the cyan ink can be selected from direct dyes such as CIDirect Blue 86 and CIDirect Blue 199, or dyes described in Japanese authorized patent JP4659403B2 and dyes described in JP5066079B2. These dyes can be used alone or in combination of two or more.

[0049] Magenta ink and yellow ink preferably contain dyes, and the dyes are not particularly limited. According to needs, at least one of acid dyes, basic dyes, direct dyes, reactive dyes, etc. can be selected and used. Among 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.

[0050] Among them, direct dyes include: CIDirect Red80, CIDirect Red227, CIDirectYellow-12, CIDirect Yellow-86, CIDirect Yellow-132, etc.

[0051] Acid dyes include: CIAcid Red 1, CIAcid Red 52, CIAcid Red 249, CIAcid Red 289, CIAcid Yellow 17, CIAcid Yellow 23, CIAcid Yellow 71, etc.

[0052] Reactive dyes include: CIReactive Red14, CIReactive Red141, CIReactive Red221, CIReactive Yellow2, CIReactive Yellow77, CIReactive Yellow163, etc.

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

[0054] 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 %.

[0055] 3. Alcoholamine compounds

[0056] 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).

[0057]

[0058] Wherein, R1 in formula (1) is a CH group 2 OH, CH 2 CH 2 Any of OH, H, R2 is a CH group 2 OH, CH 2 CH 2 Any one of OH and H.

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

[0060] When the black ink contains the alcoholamine compound, it has a particularly excellent effect. The alcoholamine compound can act as a counter ion of the self-dispersible pigment and can inhibit the aggregation between the self-dispersible pigment and the phthalocyanine dye when the cyan ink and the black ink are mixed.

[0061] 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.

[0062] 4. Polyoxyethylene alkyl ether compounds

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

[0064]

[0065] 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.

[0066] When the black ink contains the polyoxyethylene alkyl ether compound represented by the general formula (2), it has a particularly excellent effect. The polyoxyethylene alkyl ether compound represented by the general formula (2) has a polyoxyethylene part as a hydrophilic part and an alkyl part as a hydrophobic part. The alkyl part of the hydrophobic part of the polyoxyethylene alkyl ether compound shown in the general formula (2) is adsorbed on the hydrophobic part of the self-dispersible pigment, and the dispersion stability of the self-dispersible pigment is assisted by the polyoxyethylene part of the hydrophilic part. It is known that the polyoxyethylene chain will chelate with metal ions. Ionic dyes containing phthalocyanine dyes are dissolved in water as salts. When cyan ink is mixed into black ink, the aggregation of the self-dispersible pigment and the phthalocyanine dye can be inhibited by chelating the salt of the polyoxyethylene chain with the phthalocyanine dye.

[0067] 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%.

[0068] 5. Water-soluble resin

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

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

[0071] The water-soluble resin contained in the ink in 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, ethoxypolyalkylene glycol (meth)acrylate, etc.

[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 black ink contains the water-soluble resin, it has a particularly excellent effect. As described above, the water-soluble resin assists the dispersion stability of the self-dispersible pigment, and the polyoxyethylene chain of the water-soluble resin chelates with the salt of the phthalocyanine dye, thereby inhibiting the aggregation of the self-dispersible pigment and the phthalocyanine dye.

[0075] 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 %.

[0076] 6. Water-soluble organic solvents

[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, etc.

[0079] 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.

[0080] Polyol ethers: ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, etc.

[0081] 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.

[0082] Cyclic esters: β-propiolactone, γ-butyrolactone, δ-valerolactone, etc.

[0083] Nitrogen-containing solvents: urea, ethylene urea, N-methyl-2-pyrrolidone, N-substituted pyrrolidone, etc.

[0084] 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%.

[0085] 7. Surfactants

[0086] The ink of this embodiment preferably contains a surfactant. The surfactant may be at least one of anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. Nonionic surfactants are particularly preferably used. The nonionic surfactant includes at least one of an alkyl ether surfactant, an acetylene glycol surfactant, a fluorine surfactant, and an organosilicon surfactant.

[0087] The mass percentage content of the surfactant in the ink is 0.01% or more and 3.0% by 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] 8. Other ingredients

[0089] The ink may contain a pH adjuster, an antifungal agent, an antiseptic, a chelating agent, a rust preventive, a mildew preventive, an antioxidant, a reduction inhibitor, an evaporation accelerator, and the like.

[0090] For mildewproofing agents and preservatives, Proxel GXL, Proxel XL2, etc. can be used.

[0091] As the chelating agent, ethylenediaminetetraacetate, citrate, etc. can be used.

[0092] 9. Water

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

[0094] Example

[0095] The thermal bubble inkjet printer of the present invention is described in detail below in conjunction with specific embodiments, comparative examples and reference examples.

[0096] 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: 60 parts of styrene, 25 parts of n-butyl acrylate, and 15 parts of acrylic acid. The acid value of water-soluble resin 1 was 40 mgKOH / g and the weight average molecular weight was 10,000.

[0097] Water-soluble resin 2 was prepared by combining the following monomers: 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) using a known radical polymerization method. Water-soluble resin 2 had an acid value of 120 mgKOH / g and a weight average molecular weight of 9,000.

[0098] In addition, 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] The pigment dispersion 1 in the ink is prepared by placing 20 parts of carbon black, 10 parts of a water-soluble resin 1 neutralized with an aqueous potassium hydroxide solution having an acid value equal to that of the water-soluble resin 1, and 70 parts of ion exchange water in a batch-type vertical sand mill and dispersing the mixture for 3 hours. The coarse particles are then removed by centrifugation to prepare the pigment dispersion 1.

[0100] Tables 1-1, 1-2, 1-3 and 1-4 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 K-1 for No. 1 black ink. The components listed in Tables 1-1, 1-2, 1-3 and 1-4 are mixed, stirred for 30 minutes or longer, and then filtered using a 0.2 μm filter. Ink is then obtained.

[0101] In addition, the values ​​recorded in Tables 1-1, 1-2, 1-3 and 1-4 are the mass percentages of the effective ingredients, wherein water is used as the main solvent and its addition amount is used to make up the balance to 100 wt%.

[0102] Among them, 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 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.

[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 CIDirect Blue 86 CIDirect Blue 199 CIAcid Blue 9 CIAcid Red 249 5 5 5 CIDirect Yellow-86 5 5 5 Triethanolamine 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 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 margin margin margin margin margin margin Static surface tension (mN / m) 33.8 33.5 33.5 33.2 33.0 33.1

[0111] Table 2 shows two types of 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 types of recording heads with nozzle array arrangement sequences, which are respectively recorded as arrangement-1, arrangement-2, and arrangement-3.

[0112] Table 2

[0113] Print head-1 Print head-2 Way Hot Bubble Hot Bubble Heat sink none have

[0114] Table 3

[0115] Arrangement - 1 KCMY Arrangement-2 KMCY Rank-3 KYMC

[0116] The inks listed in Tables 1-1, 1-2, 1-3 and 1-4 were evaluated as follows.

[0117] 1) Inkjet stability

[0118] The inks shown in Tables 1-1, 1-2 and 1-3 were filled into the recording head having four columns of nozzles shown in Table 2 according to the nozzle arrangement order shown in Table 3, and the GB34969 image was printed on 100 sheets of plain paper using an inkjet printer. The presence or absence of image disturbance was evaluated based on the following criteria.

[0119] Better: 100 images were printed without image distortion.

[0120] Good: When printing more than 50 pages, image disturbance occurs.

[0121] Bad: Image disturbance occurs when less than 50 pages are printed.

[0122] 2) Recoverability

[0123] The print head used in the above-mentioned ejection stability evaluation was placed in an environment of 32°C and 8% RH for 2 weeks. After being placed, a dot matrix image with a pitch of 600 dpi of four color inks was printed on a plain paper of A4 size, and each dot consisted of a single ink dot that could be ejected. The recovery was evaluated using the following criteria.

[0124] Even better: All nozzles have ink ejected before the print is 50% complete.

[0125] Good: All nozzles are ejecting ink before the print is 100% complete.

[0126] Bad: At the end of printing, some nozzles still cannot eject ink.

[0127] 3) K color rendering

[0128] A black image was printed using the recording head evaluated above, and the OD was measured using eXact Basic (manufactured by x-rite Corporation) and evaluated based on the following criteria.

[0129] Better: OD 1.0 and above.

[0130] Good: OD 0.9 or higher and 1.0 or lower.

[0131] Bad: OD below 0.9.

[0132] 3)Lightfastness

[0133] A cyan image was printed using the print head evaluated above, and the image was left next to a window for 2 weeks. The image was then evaluated using eXact Basic (manufactured by x-rite) based on the following criteria.

[0134] Good: Compared with the initial cyan OD, the cyan OD remaining rate after standing is more than 90%.

[0135] Not good: Compared with the initial cyan OD, the cyan OD remaining rate after standing is less than 90%.

[0136] Table 4-1

[0137]

[0138] Table 4-2

[0139]

[0140] Table 4-3

[0141] 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 Ink K-15 K-16 K-12 K-12 K-12 K-12 C Ink C-5 C-5 C-6 C-7 C-5 C-5 M Ink M-3 M-3 M-3 M-3 M-3 M-3 Y Ink Y-3 Y-3 Y-3 Y-3 Y-3 Y-3 γK 39 35.2 35.2 35.2 35.2 35.2 γC 35.3 35.3 31 35.4 35.3 35.3 |γK–γC| 3.7 0.1 4.2 0.2 0.1 0.1 Inkjet stability good good good good not good better Recoverability not good better not good better better -- K color rendering better not good better better better -- Lightfastness good good good not good good --

[0142] It should be noted that the inkjet stability, recoverability, K color development and light resistance in Examples 1-16 and Comparative Examples 01-05 in Tables 4-1, 4-2 and 4-3 are all compared with the reference example in Table 4-3. From the results in Tables 4-1 and 4-2, when a recording head without a heat sink and with a color sorting of KCMY is used to print an image, the black nozzle column and the yellow nozzle column are located at the farthest position, which solves the problem of heat accumulation and improves the inkjet stability, and can maintain above the good evaluation standard. However, there will still be differences in inkjet stability, recoverability, K color development and light resistance due to different black ink, cyan ink, component composition and surface tension. See the evaluation results in Examples 13-16 and Comparative Examples 01-05 for details.

[0143] For Example 13: Since the ink formulation does not contain any of the above-mentioned alcoholamine compounds, polyoxyethylene alkyl ether compounds or water-soluble resins, the inkjet stability is only good, but since the K-color ink uses a sulfonic acid-based or phosphoric acid-based pigment and its static surface tension satisfies γ K ≥32.0mN / m, recoverability and K color rendering showed better degree.

[0144] For Example 14: Since the ink formulation does not contain any of the above-mentioned alcoholamine compounds, polyoxyethylene alkyl ether compounds or water-soluble resins, the inkjet 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 also only good; but the static surface tension of the K-color ink satisfies γ K ≥32.0mN / m, K color rendering is better.

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

[0146] For Example 16: Compared with Example 13, the arrangement order of the nozzle arrays in this example is adjusted, and the distance between the black nozzle array and the cyan nozzle array is slightly increased. However, since the ink formula does not contain any of the above-mentioned alcoholamine compounds, polyoxyethylene alkyl ether compounds or water-soluble resins, the inkjet stability is only good, which is basically the same as that of Example 13. In addition, since the K-color ink uses a sulfonic acid-based or phosphoric acid-based pigment, and its static surface tension satisfies γ K ≥32.0mN / m, recoverability and K color rendering showed better degree.

[0147] For Comparative Example 01: Since the ink formulation does not contain any of the above-mentioned alcoholamine compounds, polyoxyethylene alkyl ether compounds or water-soluble resins, the inkjet stability is only good. On this basis, because the static surface tension of the K color ink does not meet the γ K ≤38.0mN / m, the recoverability is poor, but because the K-color ink uses sulfonic acid or phosphate pigments, and its static surface tension meets γ K ≥32.0mN / m, the K color rendering is better.

[0148] For Comparative Example 02: Since the ink formula does not contain any of the above-mentioned amine compounds, polyoxyethylene alkyl ether compounds or water-soluble resins, the inkjet stability is only good, but because the K ink uses non-self-dispersing pigments, there is no problem of agglomeration and clogging, but this makes the K color rendering appear to be poor.

[0149] For Comparative Example 03: Since the ink formulation does not contain any of the above-mentioned alcoholamine compounds, polyoxyethylene alkyl ether compounds or water-soluble resins, the inkjet stability is only good because the static surface tension of K and C colors does not meet the |γ K – γ C |≤4.0mN / m, the recoverability is poor, but because the K-color ink uses sulfonic acid or phosphate pigments, and its static surface tension meets γ K ≥32.0mN / m, the K color rendering is better.

[0150] For Comparative Example 04: Since the ink formula does not contain any of the above-mentioned alcoholamine compounds, polyoxyethylene alkyl ether compounds or water-soluble resins, the inkjet stability is only good. However, since the C ink does not use copper phthalocyanine dyes, there is no problem of agglomeration and clogging, but this makes the light resistance poor. Since the K ink uses sulfonic acid or phosphoric acid pigments, and its static surface tension meets γ K ≥32.0mN / m, K color rendering also shows a better degree.

[0151] For Comparative Example 05: Since the nozzle adopts the arrangement-3 method instead of the arrangement-1 method, the inkjet stability is poor. However, since the relative distance between K and C is the farthest in the arrangement-3 method, it is difficult to cause mixing, agglomeration and clogging. Since the K color ink uses sulfonic acid or phosphate type pigments, and its static surface tension meets γ K ≥32.0mN / m, K color rendering is better.

[0152] 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, thereby improving the disorder of the printed image. On this basis, in view of the new problem that the black nozzle column and the cyan nozzle column are arranged adjacent to each other, thereby causing the black nozzle column to be blocked, the thermal bubble inkjet printer of the present invention can suppress the clogging of the black ink nozzle by adjusting the static surface tension of the black ink and the cyan ink to suppress the tendency of the cyan ink to mix into the nozzle at the black ink.

Claims

1. A thermal inkjet printer, comprising: A recording head having a plurality of nozzle arrays for ejecting a plurality of color inks; 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 are arranged at positions farthest apart from each other; The black ink contains a self-dispersible pigment, and the cyan ink contains a phthalocyanine dye; The static surface tension of the black ink γ K The static surface tension of the cyan ink γ C Satisfaction K ≤38.0mN / m;|γ K – γ C |≤4.0mN / m.

2. The thermal bubble inkjet printer according to claim 1, characterized in that: The self-dispersible pigment includes a functional group combined with the surface of the pigment particle, and the functional group is a sulfonic acid group or a phosphoric acid group.

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

4. The inkjet printer according to claim 3, characterized in that: The black ink contains an alcoholamine compound represented by the 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 inkjet printer according to claim 3, characterized in that: 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 straight chain or branched chain alkyl group having 12-22 carbon atoms.

6. The inkjet printer according to claim 3, characterized in that: The black ink contains a water-soluble resin having an acid value of less than 100 mgKOH / g and a non-ionic functional group.

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