Recording method and recording device

Abstract

The present invention provides a recording method and a recording apparatus, wherein the recording method can provide a recorded object with suppressed unevenness of light and dark, excellent color development and abrasion resistance, and can achieve an increase in printing speed.

Description

Technical Field

[0001] The invention relates to a recording method and a recording device. Background Art

[0002] The inkjet recording method can record high-definition images with a relatively simple device and is developing rapidly in various fields. Among them, various studies have been conducted on ejection stability, etc. For example, Patent Document 1 discloses an ink composition containing at least one color material selected from metal compounds and hollow resin particles and a polymer containing a sulfonic acid group for the purpose of improving hiding power and abrasion resistance.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2015-83684

[0004] The ink composition described in Patent Document 1 is used to record on the base layer and then record on the color image layer, thereby obtaining a recorded object with good color image visibility. However, on the other hand, in this method of laminating the base layer and the color image layer, there are problems such as a poor recording speed corresponding to the lamination and a large-sized nozzle. In addition, there is a problem that when the large-sized nozzle is not required or the recording speed is excellent, excellent image quality cannot be obtained. Summary of the invention

[0005] The present invention relates to a recording method, comprising: a white ink attaching step, in which a white ink composition containing a white colorant is ejected from a white ink nozzle and attached to a recording medium; a non-white ink attaching step, in which a non-white ink composition containing a non-white colorant is ejected from a non-white ink nozzle and attached to a recording medium; and a primary drying step, in which the white ink composition and the non-white ink composition attached to the recording medium are heated by a drying mechanism, wherein in the white ink attaching step and the non-white ink attaching step, a main scan is performed multiple times while the ink nozzle is moved relative to the recording medium, and the white ink composition and the non-white ink composition are attached to the same scanning area of ​​the recording medium by the same main scan, thereby forming a layer containing the white ink composition and the non-white ink composition.

[0006] The present invention is a recording device, comprising: a white ink nozzle, which ejects a white ink composition containing a white color material and attaches it to a recording medium; a non-white ink nozzle, which ejects a non-white ink composition containing a non-white color material and attaches it to a recording medium; a drying mechanism, which dries the white ink composition and the non-white ink composition attached to the recording medium; and a control unit, which controls the recording performed using the white ink nozzle and the non-white ink nozzle, and the recording device performs recording by the above-mentioned recording method. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is an example of a recording device used in this embodiment.

[0008] Figure 2 This is an example of the structure of an ink jet head.

[0009] Figure 3 This is an example of the structure of an ink jet head.

[0010] Figure 4 This is an example of a recording device used in this embodiment.

[0011] Description of Reference Numerals

[0012] 1: Printer; 2: Recording head; 3: Ink cartridge; 4: Slide; 5: Platen; 6: Drying mechanism; 7: Slide moving mechanism; 8: Medium conveying mechanism; 9: Guide rod; 10: Linear encoder; M: Recording medium; CONT: Control unit. DETAILED DESCRIPTION

[0013] Below, the embodiment of the present invention (hereinafter referred to as "this embodiment") is described in detail with reference to the accompanying drawings as needed, but the present invention is not limited thereto and various modifications can be made without departing from the main purpose thereof. It should be noted that in the accompanying drawings, the same elements are marked with the same symbols and will not be repeated. In addition, unless otherwise specified, the positional relationships such as up, down, left, and right are based on the positional relationships shown in the accompanying drawings. Moreover, the dimensional ratios of the accompanying drawings are not limited to the ratios shown in the drawings.

[0014] It should be noted that in this embodiment, when a white ink head and a non-white ink head are not particularly distinguished, they are simply referred to as an "ink head". Similarly, when a white ink composition and a non-white ink composition are not particularly distinguished, they are simply referred to as an "ink composition".

[0015] In addition, "main scanning" refers to the action of ejecting the ink composition from the ink jet head and attaching it to the recording medium while moving the ink jet head relative to the recording medium. The ink jet head can be mounted on a carriage, for example. The ink jet head can be moved by moving the carriage, in which case, the ink jet head is moved.

[0016] In addition, the "main scanning direction" is the moving direction of the ink jet head mentioned above, which refers to the width direction of the recording medium. It should be noted that the "main scanning" is the movement of the relative position of the ink jet head relative to the recording medium, which can be the movement of the ink jet head relative to the recording medium, or the movement of the recording medium relative to the ink jet head. This relative position movement direction is the main scanning direction. The relative position movement of the ink jet head relative to the recording medium can also be called the relative position movement of the recording medium relative to the ink jet head. In other words, it is the relative movement of the ink jet head and the recording medium.

[0017] On the other hand, "sub-scanning" refers to the action of moving the relative position of the inkjet head and the recording medium in the sub-scanning direction. The "sub-scanning direction" refers to the direction intersecting the main scanning direction. For example, recording can be performed by repeating the following actions: attaching the ink composition to a certain area of ​​the recording medium in the main scan, and then slightly moving the recording medium in the sub-scan, and then performing the next main scan, so that the ink composition is attached in a manner adjacent to or partially overlapping with the previously attached ink composition. It should be noted that "sub-scanning" is also the movement of the relative position of the inkjet head relative to the recording medium, which can be the movement of the inkjet head relative to the recording medium, or the movement of the recording medium relative to the inkjet head. The direction of this relative movement is the sub-scanning direction.

[0018] The recording can be performed by performing the main scanning and the sub-scanning a plurality of times, respectively. For example, the main scanning and the sub-scanning can be repeated alternately.

[0019] 1. Recording method

[0020] The recording method of the present embodiment is as follows: it comprises: a white ink attaching step, in which a white ink composition containing a white colorant is ejected from a white ink nozzle and attached to a recording medium; a non-white ink attaching step, in which a non-white ink composition containing a non-white colorant is ejected from a non-white ink nozzle and attached to a recording medium; and a drying step, in which the white ink composition and the non-white ink composition attached to the recording medium are heated by a drying mechanism, and in the white ink attaching step and the non-white ink attaching step, a main scan is performed multiple times while the ink nozzle is moved relative to the recording medium, and the white ink composition and the non-white ink composition are attached to the same scanning area of ​​the recording medium by the same main scan, thereby forming a layer containing the white ink composition and the non-white ink composition.

[0021] Conventionally, a white ink layer and a non-white ink layer are overlapped and formed, and the white ink layer is used as a hidden layer to record a high-quality image.

[0022] In contrast, in the present embodiment, the white ink composition and the non-white ink composition are attached to the same scan area of ​​the recording medium by the same relative scan. As can be seen from this, a single ink layer including the white ink composition and the non-white ink composition can be formed on the recording medium, and even if the white ink layer and the non-white ink layer are not formed by overlapping as in the past, there is no unevenness in light and dark, and an image with excellent color development is formed.

[0023] On the other hand, when the white ink composition and the non-white ink composition are attached to the same scanned area of ​​the recording medium by the same relative scan, the amount of ink attached to the same area at the same time increases, so that the droplets of these ink compositions are mixed on the recording medium, and uneven light and dark colors are easily generated, and the color rendering property is also easily reduced. In particular, in the case of low-absorption recording media or non-absorption recording media, this problem is likely to occur because the ink composition remains on the recording medium.

[0024] In contrast, in the recording method of the present embodiment, the ink droplets attached to the recording medium are dried quickly by performing a drying step once, thereby suppressing the flow of the ink droplets at an early stage and suppressing the above-mentioned image quality degradation.

[0025] In addition, in the present embodiment, since there is no need to form the white ink layer and the non-white ink layer in an overlapping manner, the printing speed can be further improved.

[0026] Furthermore, a head structure in which the nozzles for ejecting the white ink composition and the nozzles for ejecting the non-white ink composition are arranged in a horizontal arrangement can be provided so that the white ink composition and the non-white ink composition can be attached to the same scanning area of ​​the recording medium by the same relative scanning. Therefore, compared with the conventional head structure based on stacking, the overall size of the ink jet head can be miniaturized.

[0027] 1.1. White ink adhesion process and non-white ink adhesion process

[0028] The white ink attaching step is a step of ejecting a white ink composition containing a white color material from a white ink nozzle and attaching it to a recording medium, and the non-white ink attaching step is a step of attaching a non-white ink composition containing a non-white color material from a non-white ink nozzle to a recording medium. It should be noted that the white ink composition and the non-white ink composition may be ejected from the same ink nozzle. In other words, the white ink nozzle and the non-white ink nozzle may be separate or integrated.

[0029] In the recording method of this embodiment, the white ink composition and the non-white ink composition are attached by relative scanning between the recording head and the recording medium, and the white ink composition and the non-white ink composition are attached to the same scanning area of ​​the recording medium by the same relative scanning.

[0030] The same relative scan refers to, for example, a single scan in which the recording head moves relative to the main scanning direction intersecting the conveying direction of the recording medium in the case of a serial inkjet recording device. The scan may be a relative scan, and may be a scan in which the recording head moves relative to the recording medium, or a scan in which the recording medium moves relative to the recording head. The scan is performed while ink is ejected from the recording head to the recording medium.

[0031] For example, in a serial inkjet recording device, when the recording head reciprocates in the main scanning direction on the same area of ​​the recording medium to perform multiple scans, one of the forward path and the return path is one scan. Therefore, performing the white ink attaching process and the non-white ink attaching process by the same relative scan means that both processes are performed during one scan of the recording head.

[0032] Furthermore, attaching each ink composition to the same scanned area of ​​the recording medium means attaching the white ink composition and the non-white ink composition to the scanned area, thereby forming a single ink layer including the white ink composition and the non-white ink composition on the recording medium.

[0033] The recording head for white ink and the recording head for non-white ink scan simultaneously. In this scan (same scan), the white ink composition and the non-white ink composition are attached in the same scan area. The scan area in the scan is the area of ​​the recording medium that is scanned by the recording head in the scan. In the case of a serial inkjet recording device, it is the part on the recording medium where the recording head moves relative to the recording medium in the scan.

[0034] The attachment of white ink and non-white ink to the same scanning area of ​​the recording medium by the same relative scanning means that in the same scanning, the scanning area of ​​the recording head for white ink and the scanning area of ​​the recording head for non-white ink have the same area (overlapping area). It is sufficient as long as they have at least a part of the same area.

[0035] In this way, a layer including a white ink composition and a non-white ink composition can be formed by the same main scan. Since the layer is formed by the same main scan, the white ink composition and the non-white ink composition of the ink layer can be uniformly mixed.

[0036] The recording method of this embodiment preferably performs multiple main scans on the same area of ​​the recording medium. That is, it is preferred that after a layer containing a white ink composition and a non-white ink composition is attached to a certain area on the recording medium by a certain main scan, a layer containing a white ink composition and a non-white ink composition is attached thereon in an overlapping manner by another main scan. In this case, the main scan for attaching the white ink composition and the non-white ink composition will pass through the same scan area multiple times. The more times the scan is performed, the more ink can be attached to the desired area in multiple times (multiple passes), and the image quality of the obtained recorded object tends to be further improved.

[0037] It should be noted that when recording an arbitrary area, the number of times the ink jet head passes over the area is also referred to as a "stroke." For example, when four main scans are performed on the same scan area to deposit the white ink composition and the non-white ink composition, the number of strokes is referred to as four strokes.

[0038] For example, in Figure 2 In the example of FIG. 1 , when the length of one sub-scan in the sub-scan direction is one quarter of the length of the nozzle row N1 in the sub-scan direction, a rectangular scanning area having the length of one sub-scan in the sub-scan direction and extending in the main scanning direction is scanned four times. The number of scans observed in this way is called the number of scans or the number of strokes.

[0039] The number of scans is 1 or more, preferably 2 or more, more preferably 3 or more, further preferably 4 or more, and particularly preferably 8 or more. The upper limit is not limited, but is preferably 24 or less, and more preferably 12 or less. The greater the number of scans, the more times the ink can be attached to the rectangular area, and the better the image quality, so it is preferred.

[0040] It should be noted that when the number of strokes is small, the number of ejection points per stroke increases, so unevenness in density is likely to occur. However, on the other hand, the recording speed tends to increase, so the present invention is particularly useful in suppressing unevenness in density.

[0041] In the region of the recording medium to which the white ink composition and the non-white ink composition are attached, in the region where the non-white ink composition is attached in the largest amount, the ratio of the amount of the white ink composition attached to the amount of the non-white ink composition attached at 100% by mass is referred to as ratio A. The attachment amount ratio is expressed as a ratio of the amount of the white ink composition attached / the amount of the non-white ink composition attached, and assuming that the amounts of both attachments are equal, the ratio is 100% by mass.

[0042] The ratio A is preferably 80% by mass or less, more preferably 5 to 75% by mass, more preferably 10 to 70% by mass, and more preferably 35 to 65% by mass. When the ratio A is 80% by mass or less, the color rendering is further improved, and the unevenness of light and dark tends to be further reduced. In addition, when the ratio A is 10% by mass or more, the visual recognition tends to be further improved. It should be noted that the unit area when the adhesion amount is specified is an area with a specified area, for example, it can be an area of ​​2×2 mm.

[0043] Furthermore, when the amount of non-white ink composition attached in the area where the amount of non-white ink composition attached is the largest among the areas where the white ink composition and the non-white ink composition are attached is set as the maximum non-white ink attachment amount B, the attachment amount ratio is preferably in the following range: from the area where the amount of non-white ink composition attached is the maximum non-white ink attachment amount B in the area where the amount of non-white ink composition attached is to the area where the amount of non-white ink composition attached is 40% by mass of the maximum non-white ink attachment amount B.

[0044] It should be noted that in the area where the white ink composition and the non-white ink composition are attached, the area where the amount of non-white ink composition attached is less than 40% by mass of the maximum amount of non-white ink attached B is an area where the color of the image of the non-white ink composition is relatively light, and it is originally an area where the quality of the image is not obvious, but the ratio of the amount of attachment in this area can be set to the above range, exceed the above range, or be lower than the above range. When the image quality (OD value) is given priority, it can be set to the above range or lower than the above range. When the image quality (visual recognition) is given priority, it can be set to the above range or exceed the above range.

[0045] In the area of ​​the recording medium to which the white ink composition and the non-white ink composition are attached, the maximum amount of the white ink composition attached is preferably 10 mg / inch. 2 Below, more preferably 7.5 mg / inch 2 Below, more preferably 6.0 mg / inch 2 the following.

[0046] The lower limit of the maximum adhesion amount of the white ink composition is preferably 0.50 mg / inch 2 More preferably 1.0 mg / inch 2 More preferably, 3.0 mg / inch 2 Above, particularly preferably 5.0 mg / inch 2 above.

[0047] It should be noted that the maximum amount of the non-white ink composition deposited is not particularly limited as long as it is an amount deposited in accordance with an image to be recorded, but it is preferred that the ratio A be within the above-mentioned preferred range.

[0048] This can prevent the obtained image from becoming too white, and the visibility and color rendering properties tend to be further improved.

[0049] 1.2. Ink composition

[0050] The white ink composition used in this embodiment includes a white color material, and the non-white ink composition includes a non-white color material. The white ink composition and the non-white ink composition can be an aqueous ink composition with water as the main solvent, or a solvent-based ink composition with an organic solvent as the main solvent. Below, the components of the ink composition are exemplified by taking the aqueous ink composition as an example, but the components constituting the ink composition of this embodiment are not limited to the following components.

[0051] The white ink composition and non-white ink composition used in the present embodiment may be solvent-based inks or water-based inks, but preferably they are water-based inks. Compared with solvent-based inks, water-based inks have a relatively low content of organic solvents and are highly environmentally friendly. However, on the other hand, white inks and non-white inks of water-based inks are easily mixed, which can easily lead to reduced color rendering and uneven shades. In particular, the resulting image tends to be too white. Therefore, the present invention is particularly useful. It should be noted that the water system referred to as "water-based" ink refers to an ink that contains at least water as the main solvent component. The content of water contained in the ink, etc. is 40% by mass or more, preferably 50% by mass or more. More preferably, it is 60 to 98% by mass.

[0052] It should be noted that the non-aqueous ink is an ink containing an organic solvent as a main solvent component. The content of the organic solvent in the non-aqueous ink is preferably 40% by mass or more, and more preferably 50 to 98% by mass. The water content of the non-aqueous ink is preferably 1% by mass or less, and more preferably 0.5% by mass or less. The components other than the solvent component of the non-aqueous ink can be the same as the components that can be contained in the aqueous ink described later.

[0053] In the case of a water-based ink composition, in addition to the above-mentioned color materials, the white ink composition and the non-white ink composition may further contain water, an organic solvent, a surfactant, resin particles, wax, etc., as required. Hereinafter, each component of the ink composition will be described in detail using a water-based ink as an example.

[0054] 1.2.1. White color material

[0055] As white color material, there is no particular limitation, and examples thereof include CI pigment white 6, 18, 21, silica, alumina, titanium dioxide, zinc oxide, antimony oxide, magnesium oxide, zirconium oxide, zinc sulfide, barium sulfate, calcium carbonate and other white inorganic pigments. In addition to the white inorganic pigments, white organic pigments such as white hollow resin particles and polymer particles can also be used.

[0056] As the white color material, titanium dioxide is preferably used among the above examples from the viewpoint of good whiteness, etc. The white color material may be used alone or in combination of two or more.

[0057] The content of the white colorant is preferably 5.0% by mass or more, more preferably 8.0% by mass or more, and further preferably 10% by mass or more relative to the total amount of the white ink composition. In addition, the content of the white colorant is preferably 20% by mass or less, more preferably 16% by mass or less, and further preferably 14% by mass or less relative to the total amount of the white ink composition. It is further preferably 13% by mass or less.

[0058] When the content of the white colorant is within the above range, a higher quality image can be obtained.

[0059] The white colorant is preferably capable of being stably dispersed in a dispersion medium, and thus a dispersant may be used to disperse it. As the dispersant, a resin dispersant may be cited, and the dispersant may be selected from dispersants that can provide good dispersion stability of the white colorant in a white ink composition containing the white colorant. In addition, the white colorant may be used as a self-dispersible pigment by, for example, oxidizing or sulfonating the pigment surface with ozone, hypochlorous acid, oleum, etc. to modify the surface of the pigment particles.

[0060] 1.2.2. Non-white color materials

[0061] As non-white color materials, there is no particular limitation as long as they are color materials other than the above-mentioned white color materials, for example, inorganic pigments such as carbon black (CI Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black can be cited; organic pigments such as quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthraquinone pigments, anthraquinone pigments, indanthraquinone pigments, yellow anthraquinone pigments, perylene pigments, diketopyrrolopyrrole pigments, purple cyclic ketone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments. Non-white color materials can be used alone or in combination of two or more.

[0062] The content of the non-white colorant is preferably 0.5 to 10% by mass, more preferably 0.5 to 7.5% by mass, further preferably 1.0 to 6.0% by mass, and further preferably 1.5 to 4.0% by mass, relative to the total amount of the non-white ink composition.

[0063] When the content of the non-white colorant is within the above range, the color rendering properties and the visual recognition properties are further improved, and a higher quality image can be obtained.

[0064] The non-white colorant is preferably capable of being stably dispersed in a dispersion medium, and thus a dispersant may be used to disperse it. As the dispersant, a resin dispersant may be cited, and the dispersant may be selected from those that can provide good dispersion stability of the non-white colorant in a non-white ink composition containing the non-white colorant. In addition, the non-white colorant may be used as a self-dispersible pigment by, for example, oxidizing or sulfonating the pigment surface with ozone, hypochlorous acid, fuming sulfuric acid, etc. to modify the surface of the pigment particles.

[0065] The non-white ink composition containing the non-white color material is not limited, and examples thereof include cyan ink, yellow ink, magenta ink, and black ink.

[0066] 1.2.3. Water

[0067] The water content is preferably 40 to 98% by mass, more preferably 50 to 85% by mass, more preferably 55 to 80% by mass, and even more preferably 60 to 75% by mass, relative to the total amount of the ink composition.

[0068] 1.2.4. Organic solvents

[0069] The organic solvent is not particularly limited as long as it is a water-soluble organic solvent, and examples thereof include: polyols of triols or higher such as glycerol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol; Glycol ethers such as glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether; nitrogen-containing solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone; alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol, tert-butanol, isobutanol, n-pentanol, 2-pentanol, 3-pentanol and tert-pentanol, etc. The organic solvent may be used alone or in combination of two or more.

[0070] Diols are compounds having two hydroxyl groups in the molecule. Examples of diols include alkanediols in which an alkane is substituted with two hydroxyl groups, and condensates in which hydroxyl groups of two or more molecules of the alkanediol are condensed with each other in molecules.

[0071] The number of carbon atoms in the molecule of the diol is preferably 2 to 10, more preferably 3 to 8, further preferably 3 to 6, particularly preferably 3 to 5.

[0072] Preferred examples of diols include propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,5-pentanediol, and 1,2-hexanediol. Preferred examples of alkanediols include 1,2-alkanediol and double-end alkanediol.

[0073] Examples of the nitrogen-containing solvent include amide solvents, and examples of the amide solvent include acyclic amides and cyclic amides.

[0074] Examples of cyclic amides include lactams, for example, pyrrolidones such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, and 1-butyl-2-pyrrolidone, N-methyl-ε-caprolactam, N-cyclohexyl-2-pyrrolidone, and β-propiolactam.

[0075] Examples of the acyclic amides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, 3-ethoxy-N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-dimethylpropionamide, 3-n-butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methylethylpropionamide, 3-n-propoxy-N,N-dimethylpropionamide, 3-n-propoxy-N,N-diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, Amides, alkoxyalkylamides such as 3-isopropoxy-N,N-dimethylpropionamide, 3-isopropoxy-N,N-diethylpropionamide, 3-isopropoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, 3-tert-butoxy-N,N-methylethylpropionamide, N,N-dimethylacetoacetamide, N,N-diethylacetoacetamide, N-methylacetoacetamide, N,N-dimethylisobutyric acid amide, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylpropionamide, etc.

[0076] Triols and higher polyols are compounds having three or more hydroxyl groups in the molecule, and an example thereof is glycerol.

[0077] Glycol ethers are compounds in which one or two hydroxyl groups of an alkanediol in which an alkane is substituted with two hydroxyl groups or a condensate in which two or more hydroxyl groups of the alkanediol molecules are condensed with each other intermolecularly is etherified. The etherification is monoetherification or dietherification. The etherification is preferably alkyl etherification. Glycol ethers are compounds having one hydroxyl group or no hydroxyl group in the molecule. Examples of the glycol ethers include the above-mentioned glycol ethers.

[0078] Alcohols are compounds in which an alkane is substituted with a hydroxyl group, and have one hydroxyl group in the molecule. Examples of alcohols include the above-mentioned alcohols.

[0079] The use of such an organic solvent tends to further improve the ejection stability of the ink and the abrasion resistance of the obtained recorded matter, and further reduce the unevenness of light and dark areas.

[0080] The content of the organic solvent is preferably 40% by mass or less relative to the total amount of the ink composition. Further, it is preferably 30% by mass or less, more preferably 5.0 to 27.5% by mass, further preferably 10 to 25% by mass, further preferably 15 to 22% by mass, and on the other hand, it is preferably 20 to 33% by mass.

[0081] The content of the diol-based organic solvent may be within the above range.

[0082] The content of the nitrogen-containing solvent is preferably 40% by mass or less, more preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less, relative to the total amount of the ink composition. The lower limit is 0% by mass or more.

[0083] When the content of the organic solvent is within the above range, the abrasion resistance of the obtained recorded material is further improved, the unevenness of light and dark is further reduced, and the recording speed tends to be further increased. When the content of the nitrogen-containing solvent is below the above range, the image quality, abrasion resistance, etc. are more excellent, so it is preferred.

[0084] The normal boiling point of the organic solvent is preferably 280° C. or less. Further, it is preferably 150 to 280° C., preferably 160 to 270° C., and preferably 170 to 260° C. Further, it is preferably 180 to 200° C., and more preferably 190 to less than 200° C. When the normal boiling point of the organic solvent is within the above range, the abrasion resistance is further improved, and the unevenness of light and dark tends to be further reduced.

[0085] The content of the organic solvent having a normal boiling point of less than 200° C. in the organic solvent contained in the white ink composition or the non-white ink composition is 0% by mass or more, preferably 40% by mass or more, more preferably 50% by mass or more, more preferably 55% by mass or more, more preferably 60% by mass or more, and more preferably 70% by mass or more, relative to the total amount of the organic solvent. The upper limit of the content of the organic solvent having a normal boiling point of less than 200° C. is 100% by mass or less, preferably 95% by mass or less, more preferably 90% by mass or less, and more preferably 70% by mass or less.

[0086] It is particularly preferred that the content of the organic solvent having a normal boiling point of less than 200° C. in the white ink composition is within the above range. The content of the organic solvent having a normal boiling point of less than 200° C. in the above range tends to further improve the abrasion resistance and further reduce the unevenness of light and dark.

[0087] The content of the organic solvent having a standard boiling point of 200° C. or higher in the organic solvent contained in the white ink composition or the non-white ink composition is 100% by mass or less, preferably 60% by mass or less, more preferably 50% by mass or less, more preferably 45% by mass or less, more preferably 40% by mass or less, and more preferably 30% by mass or less, relative to the total amount of the organic solvent. In addition, the lower limit of the content of the organic solvent having a standard boiling point lower than 200° C. is 0% by mass or more, preferably 5% by mass or more, and may be 10% by mass or more. The content of the organic solvent having a standard boiling point of 200° C. or higher within the above range tends to further improve the abrasion resistance and further reduce the unevenness of light and dark.

[0088] In addition, it is preferred that the white ink composition or the non-white ink composition contains an organic solvent having a normal boiling point within the above-mentioned range as the glycol-based organic solvent.

[0089] The white ink composition or non-white ink composition preferably contains both an organic solvent having a normal boiling point of less than 200° C. and an organic solvent having a normal boiling point of 200° C. or higher. Such a solvent composition tends to further improve abrasion resistance and further reduce unevenness in density.

[0090] It is preferred that the organic solvent having a normal boiling point of less than 200° C. and the organic solvent having a normal boiling point of 200° C. or higher be a glycol-based organic solvent.

[0091] In addition, the maximum value of the standard boiling point of the organic solvent contained in the white ink composition or the non-white ink composition is preferably 280°C or less, more preferably 250°C or less, more preferably 240°C or less, and more preferably 230°C or less. In addition, the maximum value of the standard boiling point of the organic solvent is preferably 150°C or more, more preferably 160°C or more. It is particularly preferred that the maximum value of the standard boiling point of the organic solvent contained in the white ink composition is within the above range. When the maximum value of the standard boiling point is within the above range, there is a tendency that the abrasion resistance is further improved and the unevenness of light and dark is further reduced.

[0092] It is particularly preferred that the white ink composition and the non-white ink composition are each an aqueous ink composition, and do not contain more than 2% by mass of an organic solvent of a diol or a polyol having a normal boiling point exceeding 280° C. or higher than a triol. “Not containing more than 2% by mass” means that it may contain 0% by mass, or may contain within a range not exceeding the mass %. It is more preferred that the above range does not contain more than 1% by mass, and it is more preferred that the above range does not contain more than 0.5% by mass. In addition, the content of an organic solvent other than an organic solvent of a polyol having a normal boiling point exceeding 280° C. is also preferably within the above range.

[0093] 1.2.5. Surfactants

[0094] The surfactant is not particularly limited, and examples thereof include acetylene glycol surfactants, fluorine surfactants, and silicone surfactants. Among them, silicone surfactants are preferred. This tends to further suppress uneven light and dark properties of the obtained recorded material.

[0095] The acetylene glycol-based surfactant is not particularly limited, but is preferably one or more selected from 2,4,7,9-tetramethyl-5-decyn-4,7-diol and an alkylene oxide adduct of 2,4,7,9-tetramethyl-5-decyn-4,7-diol, and 2,4-dimethyl-5-decyn-4-ol and an alkylene oxide adduct of 2,4-dimethyl-5-decyn-4-ol.

[0096] The fluorine-based surfactant is not particularly limited, and examples thereof include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates, perfluoroalkyl phosphates, perfluoroalkyl ethylene oxide adducts, perfluoroalkyl betaines, and perfluoroalkyl amine oxide compounds.

[0097] Examples of the silicone-based surfactant include polysiloxane-based compounds and polyether-modified silicone siloxanes.

[0098] The content of the surfactant is preferably 0.1 to 4.0% by mass, more preferably 0.3 to 3.0% by mass, and even more preferably 0.5 to 2.0% by mass relative to the total amount of the ink composition. This tends to further suppress uneven density of the resulting recorded material.

[0099] 1.2.6. Resin particles

[0100] The use of resin particles can further improve the abrasion resistance of the obtained image. The resin particles are not particularly limited, and examples thereof include resin particles composed of urethane resins, acrylic resins (including styrene-acrylic resins), fluorene resins, polyolefin resins, rosin-modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, vinyl chloride resins, vinyl chloride-vinyl acetate copolymers, ethylene vinyl acetate resins, etc. The resin particles may be in the form of an emulsion.

[0101] Among them, urethane resin, acrylic resin, and polyolefin resin are preferred. Most of these resin particles are processed in the form of emulsion, but they can also be in the form of powder. In addition, the resin particles can be used alone or in combination of two or more.

[0102] Urethane resin is a general term for resins having urethane bonds. Urethane resins that can be used include polyether urethane resins having ether bonds in the main chain, polyester urethane resins having ester bonds in the main chain, and polycarbonate urethane resins having carbonate bonds in the main chain.

[0103] Acrylic resin is a general term for polymers obtained by polymerizing acrylic monomers such as (meth)acrylic acid and (meth)acrylate as at least one component, and examples thereof include resins obtained from acrylic monomers, copolymers of acrylic monomers and monomers other than acrylic monomers, and the like. For example, acrylic acid-ethylene resins, which are copolymers of acrylic monomers and vinyl monomers, and the like can be cited. In addition, for example, as vinyl monomers, styrene and the like can be cited. As acrylic monomers, acrylamide, acrylonitrile, and the like can also be used.

[0104] Among them, styrene-acrylic acid resin is preferred. There are no particular restrictions on the styrene-acrylic acid resin, and examples thereof include styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylate copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylate copolymer, etc. The use of such resins tends to further improve the image quality and abrasion resistance of the obtained recorded material.

[0105] The polyolefin-based resin is a material having an olefin such as ethylene, propylene, or butene in its structural skeleton, and any known polyolefin-based resin can be appropriately selected and used.

[0106] The content of the resin particles is preferably 0.5 to 15% by mass, preferably 1.0 to 10% by mass, and more preferably 2.5 to 7.5% by mass relative to the total amount of the ink composition. The content of the resin particles within the above range tends to further improve the abrasion resistance of the obtained recorded material.

[0107] 1.2.7. Wax

[0108] The wax is not particularly limited, and examples thereof include plant and animal waxes such as carnauba wax, candelilla wax, beeswax, rice bran wax, and lanolin; petroleum waxes such as paraffin wax, microcrystalline wax, polyethylene wax, oxidized polyethylene wax, and petrolatum; mineral waxes such as montan wax and ozokerite; synthetic waxes such as carbowax, Hoechst wax, polyolefin wax, and stearic acid amide; natural and synthetic wax emulsions and formulated waxes such as α-olefin maleic anhydride copolymers. One wax may be used alone, or two or more waxes may be used in combination. The wax may be an emulsion.

[0109] Among them, polyolefin waxes (especially polyethylene wax and polypropylene wax) and paraffin wax are preferably used. The use of such waxes tends to further improve the abrasion resistance of the obtained recorded material.

[0110] The wax content is preferably 0.1 to 7.5% by mass, more preferably 0.3 to 5.0% by mass, and even more preferably 0.5 to 2.5% by mass relative to the total amount of the ink composition. When the wax content is within the above range, the abrasion resistance of the resulting recorded material tends to be further improved.

[0111] 1.2.8. Other ingredients

[0112] The ink composition may further contain components such as an antiseptic, an antifungal agent, an antirust agent, a chelating agent, a viscosity modifier, an antioxidant, and an antifungal agent as required.

[0113] 1.3. Primary drying process

[0114] The primary drying step is a step of drying the white ink composition and the non-white ink composition attached to the recording medium by the drying mechanism at an early stage. In particular, it means that in the white ink attaching step and the non-white ink attaching step, the area to which the white ink composition and the non-white ink composition are attached is dried at an early stage.

[0115] The primary drying process is a process for drying the ink attached to the recording medium at an early stage. The primary drying process is a process for drying at least a part of the solvent component of the ink attached to the recording medium to at least a degree that reduces the flow of the ink. The primary drying process may be performed by attaching the ink composition to the heated recording medium, or may be performed at a position of the recording medium opposite to the ink nozzle, or may be performed at an early stage after attachment. The primary drying process preferably starts drying the ink droplets attached to the recording medium within 0.5 seconds from the attachment of the ink droplets.

[0116] The drying mechanism in the primary drying process is not particularly limited, and examples thereof include a conduction type using a platen heater, a preheater, etc., a radiation type using an IR heater, etc., and an air supply type (air supply) using an air supply fan, etc. The air supply promotes evaporation by removing the evaporated solvent component from the medium, thereby achieving excellent image quality. The air supply type is not limited to warm air, and may also be normal temperature air. Normal temperature air is also preferred because it does not cause thermal effects on the nozzle.

[0117] The drying mechanism is also called a drying unit. The drying unit may be used alone or in combination of two or more. It is particularly preferred to use any one of the conduction type and the radiation type and the air supply type, and it is more preferred to use the conduction type and the air supply type. In this case, heating can be performed by any one of the conduction type and the radiation type, and evaporation can be promoted by the air supply type, so that the image quality is better. In this case, the air supply of the air supply type can be warm air or normal temperature air, but considering that the ejection stability is better, normal temperature air is preferred.

[0118] The wind speed of the air supply is preferably 0.5 to 5 m / s, more preferably 0.5 to 4 m / s, and further preferably 0.5 to 3 m / s. The wind speed of the air supply is within the above range so that the air supply can promote evaporation by removing the evaporated solvent component from the medium and has a tendency to be less likely to cause a spray bend caused by the wind. The wind speed is the wind speed near the recording medium.

[0119] The air temperature of the air supply may be room temperature air or warm air, but is preferably 10 to 50° C., more preferably 15 to 45° C., further preferably 20 to 40° C., and particularly preferably 25 to 30° C. When the air temperature of the air supply is within the above range, the evaporation of the ink can be promoted and the ejection stability is excellent, so it is preferred.

[0120] The surface temperature of the recording medium in the primary drying step is preferably 25°C or higher. Also, it is preferably 60°C or lower. Furthermore, it is preferably 30 to 50°C, more preferably 35 to 45°C, and even more preferably 40 to 45°C. Alternatively, it is preferably 30 to 40°C, and more preferably 30 to 35°C.

[0121] The surface temperature of the recording medium in the primary drying process was set to the maximum temperature during recording.

[0122] When the surface temperature of the recording medium in the primary drying step is within the above range, the abrasion resistance and visibility tend to be further improved, and unevenness in shading tends to be suppressed.

[0123] 1.4. Secondary drying process

[0124] For the purpose of further drying the recorded object, the recording method of this embodiment may have a secondary drying process after the primary drying process. The secondary drying process refers to drying the recording medium to which the ink composition is attached to be fully dried to the extent that the recorded object can be used, and refers to drying performed to complete the recording. The secondary drying may include heating for flattening the components such as the resin contained in the ink composition. The heating is preferably started after all the ink to be attached to a certain area of ​​the recording medium is attached, and more than 0.5 seconds have passed since the attachment is completed.

[0125] The secondary drying step is also called a post-drying step. The secondary drying step is preferably heated. The surface temperature of the recording medium in the secondary drying step is preferably 50 to 120°C, more preferably 50 to 100°C, and even more preferably 60 to 90°C.

[0126] The drying method in the secondary drying step is not particularly limited, and examples thereof include a conduction method using a platen heater or preheater, a radiation method using an IR heater, and an air supply method using an air supply fan.

[0127] 1.5. Recording Media

[0128] The recording medium used in this embodiment is not particularly limited, and examples thereof include absorptive recording media such as paper, film, and cloth, low-absorptive recording media such as printing paper, and non-absorptive recording media such as metal, glass, and polymers.

[0129] Among them, from the perspective of ink absorption, low-absorption recording media or non-absorption recording media are preferred. In addition, from the perspective of color, non-white recording media are preferred. Such recording media have been formed by overlapping a white ink layer and a non-white ink layer, and the white ink layer is used as a hidden layer to record high-quality images. Therefore, by using the present invention, the following effects of the present invention can be particularly effectively exerted: an image with no uneven shades and excellent color rendering can be formed.

[0130] In this embodiment, the non-absorbing or low-absorbing recording medium refers to "the recording medium that is not absorbed by the Bristow method from the time of contact to 30 msec. 1 / 2 The water absorption is 10mL / m 2The Bristol method is the most popular method for measuring the amount of liquid absorbed in a short period of time and is also adopted by the Japan Pulp and Paper Technology Association (JAPAN TAPPI). The details of the test method are recorded in Standard No. 51 "Paper and Paperboard-Liquid Absorption Test Method-Bristol Method" of "JAPAN TAPPI Pulp and Paper Test Method 2000 Edition".

[0131] Examples of non-absorbent recording media include recording media in which a substrate such as paper is coated with plastic, recording media in which a plastic film is bonded to a substrate such as paper, and plastic films without an absorbing layer (receiving layer). Examples of the plastics mentioned here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

[0132] In addition, as low-absorption recording media, for example, there can be cited recording media with a low-absorption coating layer on the surface. For example, there can be cited recording media called coated paper. For example, as recording media whose substrate is paper, there can be cited printing papers such as art paper, coated paper, and matte paper. When the substrate is a plastic film, there can be cited recording media whose surfaces are coated with polymers such as polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene, and recording media coated with particles of silicon dioxide, titanium, etc. together with an adhesive.

[0133] As the recording medium, an absorptive recording medium may also be used. The absorptive recording medium refers to the above-mentioned "from the start of contact to 30 msec in the Bristow method". 1 / 2 The water absorption is more than 10mL / m 2 recording medium".

[0134] As non-white recording medium, transparent recording medium (transparent recording medium) can be cited. The transparent recording medium can be colorless and transparent, colored (colored) transparent. In addition, transparency also includes translucent. These are recording media with light transmittance by visual inspection. They are also visible light translucent recording media. In this case, by the recording method of this embodiment, the image formed on one side of the recording medium can be well visually recognized from both sides.

[0135] As non-white recording media, non-white colored recording media (non-white colored recording media) can be cited. Non-white colored opaque recording media, non-white colored transparent recording media, etc. can be cited. In this case, it is also possible to easily form an image with good visual recognition, reduced image quality such as smearing and poor image quality by the recording method of this embodiment. The non-white colored recording medium can be the above-mentioned transparent recording medium or a non-transparent recording medium. The non-transparent recording medium is a recording medium that is not light-transmissive by visual inspection. It is also a visible light opaque recording medium. Among them, the non-white colored is a colored other than white.

[0136] 2. Recording device

[0137] The recording device of this embodiment comprises: a white ink nozzle, which ejects a white ink composition containing a white colorant and attaches it to a recording medium; a non-white ink nozzle, which ejects a non-white ink composition containing a non-white colorant and attaches it to a recording medium; a drying mechanism, which dries the white ink composition and the non-white ink composition attached to the recording medium; and a control unit, which controls the recording performed using the white ink nozzle and the non-white ink nozzle, and the recording device records by the above-mentioned recording method.

[0138] Hereinafter, an example of a recording device used in the present embodiment will be described with reference to the drawings, but the recording device used in the present embodiment is not limited to the following.

[0139] Figure 1 An example of a recording device used in this embodiment is shown. Figure 1 In the description, a carriage-mounted printer in which the ink cartridge is mounted on the carriage is used as an example, but the recording device is not limited to the carriage-mounted printer, and may be a non-carriage-mounted printer in which the ink cartridge is fixed to the outside. In the case of the non-carriage-mounted printer, as long as the ink cartridge 3 is mounted somewhere other than the carriage 4, the ink can be supplied from the ink cartridge 3 to the recording head 2 via the ink supply pipe.

[0140] It should be noted that the printer used in the following description is a serial printer, in which a carriage moving in a predetermined direction carries an inkjet head for recording, and the inkjet head moves with the movement of the carriage, thereby ejecting droplets onto a recording medium. It should be noted that the serial type may be a method of performing a main scan in a direction intersecting the conveying direction of the recording medium, i.e., the sub-scanning direction, or a transverse type in which the inkjet head alternately moves in the main scanning direction and the sub-scanning direction relative to a fixed recording medium.

[0141] like Figure 1As shown, the printer 1 includes a recording head 2, an ink cartridge 3, a carriage 4, a platen 5, a drying mechanism 6, a carriage moving mechanism 7, a medium conveying mechanism 8, a guide rod 9, a linear encoder 10, and a control unit CONT.

[0142] The control unit CONT controls the overall operation of the printer 1. The carriage 4 carries the recording head 2 described later, and is detachably mounted with an ink cartridge 3 for supplying each ink composition to the recording head 2. The platen 5 is arranged below the recording head 2, and is fed with a recording medium M as a recording medium. The drying mechanism 6 heats the recording medium M. The carriage moving mechanism 7 moves the carriage 4 in the medium width direction of the recording medium M. The medium conveying mechanism 8 conveys the recording medium M along the medium conveying direction. The medium width direction refers to the main scanning direction MS as the operating direction of the recording head 2. The medium conveying direction is a direction orthogonal to the main scanning direction MS, and is a sub-scanning direction SS in which the recording medium M moves.

[0143] The recording head 2 is a unit for attaching each ink composition to the recording medium M. The recording head 2 has a first nozzle for ejecting a white ink composition and a second nozzle for ejecting a non-white ink composition on the surface facing the recording medium M to which each ink composition is attached. These multiple nozzles are arranged in a row, thereby forming a nozzle surface on the surface of the nozzle plate. Figure 1 In the embodiment, the recording head 2 serves as both a white ink ejection head and a non-white ink ejection head.

[0144] As a method for ejecting the white ink composition or the non-white ink composition from the nozzle, for example, a piezoelectric method can be cited, in which a piezoelectric element is used to simultaneously apply pressure and a recording information signal to the white ink composition or the non-white ink composition, so that droplets of the ink or the non-white ink composition are ejected and recorded. In addition, as the recording head 2, in addition to the ink jet head, a dot matrix head, a thermal transfer head, etc. can also be used.

[0145] Figure 2 The nozzle formation surface when the inkjet head is used as the recording head 2. When the white ink composition is ejected from the nozzle array N1 and the non-white ink composition is ejected from the nozzle array N2 for scanning, the nozzle array N1 and the nozzle array N2 have an overlapping portion in the sub-scanning direction SS when projected in the main scanning direction MS. In this case, the white ink composition and the non-white ink composition are attached to the same area of ​​the recording medium by one scanning of the inkjet head.

[0146] In the above example, the same area is a portion where the nozzle row N1 and the nozzle row N2 overlap in the sub-scanning direction SS when the nozzle row N1 ejecting white ink and the nozzle row N2 ejecting non-white ink are projected in the main scanning direction MS.

[0147] in addition, Figure 3Another way to represent an inkjet head. Figure 3 In the ink jet head described above, the area is further divided into blocks B1 and B2 in the sub-scanning direction SS. In the ink jet head, the type of droplets ejected can be changed by block and nozzle row. For example, Figure 3 In the embodiment, the ink jet head can be configured to eject white ink in the block B1 of the nozzle row N1 and eject non-white ink in the blocks B1-2 of the nozzle row N2. In this way, by further dividing the blocks in the sub-scanning direction SS of the ink jet head, a more flexible ejection method can be achieved.

[0148] In this case, the white ink composition and the non-white ink composition are also attached to the same area of ​​the recording medium facing the block B1 by the same main scanning.

[0149] exist Figure 1 In the embodiment, the ink cartridge 3 for supplying the white ink composition and the like to the recording head 2 is composed of four independent ink cartridges. For example, three of the four ink cartridges are filled with different types of non-white ink compositions, and one is filled with a white ink composition. The ink cartridge 3 is detachably mounted relative to the recording head 2. Figure 1 In the example shown in FIG. 1 , the number of ink cartridges is four, but the present invention is not limited thereto, and a required number of ink cartridges can be mounted.

[0150] The carriage 4 is installed in a state supported by a guide rod 9 as a supporting member provided in the main scanning direction, and is moved in the main scanning direction along the guide rod 9 by the carriage moving mechanism 7. Figure 1 In the example shown in FIG. 1 , the carriage 4 moves in the main scanning direction, but the present invention is not limited thereto and the carriage 4 may move in the sub-scanning direction in addition to the movement in the main scanning direction.

[0151] The drying mechanism 6 may be disposed at a position where it can heat the recording medium M, and its location is not particularly limited. Figure 1 In the example of , the drying mechanism 6 is disposed on the platen 5 at a position opposite to the recording head 2. When the drying mechanism 6 is disposed at a position opposite to the recording head 2, the attachment position of the ink or non-white ink composition in the recording medium M can be reliably heated, and the white ink composition or non-white ink composition attached to the recording medium M can be effectively dried.

[0152] Examples of the drying mechanism 6 include a print heater mechanism that heats the recording medium M by bringing it into contact with a heat source, a mechanism that irradiates infrared rays or microwaves, which are electromagnetic waves having a maximum wavelength of about 2450 MHz, and a dryer mechanism that blows warm air.

[0153] The drying mechanism 6 heats the recording medium M before, when, or immediately after the droplets ejected from the nozzles of the recording head 2 adhere to the recording medium M. The control unit CONT controls various heating conditions, such as the timing of heating, heating temperature, and heating time.

[0154] The linear encoder 10 detects the position of the carriage 4 in the main scanning direction in the form of a signal. The signal detected by the linear encoder 10 is sent to the control unit CONT as position information. The control unit CONT recognizes the scanning position of the recording head 2 based on the position information from the linear encoder 10, and controls the recording operation, that is, the ejection operation, etc. of the recording head 2. It should be noted that the control unit CONT is configured to be able to variably control the moving speed of the carriage 4.

[0155] Figure 4 Indicates viewing from the side Figure 1 A schematic cross-sectional view of the ink jet head and the surroundings of a recording device. Figure 4 The recording device 100 includes a carriage 2, an ink jet head 3, a platen 4, a platen heater 4a, a preheater 7, an IR heater 8, an air supply fan 8a, a post heater 5, and a cooling fan 5a. Recording is performed on a recording medium 1.

[0156] As the drying mechanism used in the primary drying process, a conduction type using the platen heater 4a or the preheater 7, a radiation type using the IR heater 8, and an air supply type using the air supply fan 8a can be used. The primary drying process is performed using at least any one of them. In the air supply using the air supply fan 8a, the ink attached to the recording medium can be supplied with air in the recording medium near the position opposite to the ink nozzle 4 in the recording medium conveying direction to promote evaporation. The post-heater 5 is a drying mechanism used in the secondary drying process.

[0157] Example

[0158] The present invention will be described in more detail below using Examples and Comparative Examples. The present invention is not limited to the following Examples.

[0159] 1. Ink composition

[0160] Each material was mixed in the composition shown in Table 1 below and stirred thoroughly to obtain each ink composition. Specifically, the ink composition was prepared by uniformly mixing each material and removing insoluble matter with a filter. It should be noted that in Table 1 below, the unit of the numerical value is mass %, and the total is 100.0 mass %. In addition, unless otherwise specified, it represents the solid content.

[0161] It should be noted that the color material is mixed and stirred with a dispersant in advance to prepare a pigment dispersion, which is used in the preparation of ink. As a dispersant, a dispersant resin is used, and commercial products suitable for each pigment are mixed in a mass ratio of 2:1 for pigment: dispersant.

[0162]

Table 1

[0163]

[0164] ※The values ​​in parentheses for organic solvents indicate their standard boiling points.

[0165] Styrene acrylic resin: manufactured by BASF, product name Joncryl 537J

[0166] Polyethylene wax: BYK, product name AQUACER 539

[0167] BYK348: Made by BYK, silicone surfactant

[0168] 2. Evaluation

[0169] As a recording device, a modified serial inkjet printer (trade name SC-S80650) was prepared. The nozzle density per nozzle row was 360 npi and the number of nozzles was 360.

[0170] In the example where the recording mode is "simultaneous", Figure 2 The ink jet head has nozzles arranged in a horizontal direction in the main scanning direction. The resolution during recording is 720×720 dpi.

[0171] The number of ink drops per pixel and the ink volume of the ink droplets are adjusted so that the adhesion amount at this resolution is the value in the table. The number of ink drops per stroke is also adjusted.

[0172] Then, a recording test was performed using the above-mentioned recording apparatus to obtain a recorded object under the conditions shown in Tables 2 to 4. Specifically, each ink composition was recorded on a recording medium (PET50A (transparent film), manufactured by LINTEC) under the conditions of each recording example at a predetermined adhesion amount and number of strokes to record a solid image.

[0173] In the example of attaching white ink and non-white ink "simultaneously", the first nozzle row of the horizontal arrangement head is filled with white ink, and the second nozzle row is filled with color ink, and they are ejected simultaneously in the same main scan with the number of strokes listed in the table.

[0174] In the example of attaching white ink and non-white ink in a "layered" manner, the white ink nozzle is arranged at a position upstream of the color ink nozzle in the medium conveying direction, and the white ink is first printed with the number of strokes recorded in Tables 2 to 4, and then the color ink is recorded in an overlapping manner with the number of strokes recorded in Tables 2 to 4.

[0175] The ink adhesion amount is the adhesion amount in an area of ​​2×2 mm in the recording pattern.

[0176] In addition, the recording device is set as follows Figure 4 The platen heater and air supply fan are provided. The air supply fan wind speed is the wind speed near the paper surface and is set to the values ​​listed in Tables 2 to 4. The wind temperature is the wind temperature near the surface of the recording medium. The wind temperature is set and measured in advance without the influence of the temperature of the platen heater, and the recording is performed under the set conditions.

[0177] The heating intensity of the platen heater was adjusted so that the surface temperature of the recording medium would become the value in the table.

[0178] Furthermore, a secondary drying process was performed using a secondary heater located downstream so that the surface temperature of the recording medium reached 70°C.

[0179] 2.1. Abrasion resistance

[0180] The recorded material obtained as described above was subjected to a Gakushin type friction color fastness tester (manufactured by Tester Sangyo Co., Ltd.) by placing a cloth on the surface of the coating film and rubbing it back and forth 50 times with a load of 500 g. The peeling and scratches on the surface of the coating film after rubbing were visually observed, and the abrasion resistance was evaluated according to the following evaluation criteria.

[0181] Evaluation Criteria

[0182] A: I don’t think there is image peeling

[0183] B: Less than 10% peeling

[0184] C: 10% or more and less than 40% peeling

[0185] D: 40% or more of the area is peeled off

[0186] 2.2. Ejection stability

[0187] Recording was performed continuously for 2 hours under the conditions shown in Tables 2 to 4. It was assumed that the recording was simulated in which no ink was ejected from the ink jet head after recording. After the recording, suction cleaning was performed to discharge 1cc, and the nozzles were checked to confirm whether there were any nozzles that did not eject. If there were any nozzles that did not eject, suction cleaning was performed again, and the number of cleanings until all nozzles were restored was counted. The ejection stability was evaluated according to the following evaluation criteria.

[0188] Evaluation Criteria

[0189] A: All nozzles are restored after one cleaning.

[0190] B: After 2-3 cleanings, all nozzles are restored

[0191] C: After 4 to 6 cleanings, all nozzles are restored

[0192] D: There are nozzles that do not recover after 6 cleanings.

[0193] 2.3. Image quality (uneven light and dark)

[0194] The pattern image of the recorded product obtained as described above was visually confirmed, and the density unevenness of the printed product was evaluated according to the following evaluation criteria.

[0195] Evaluation Criteria

[0196] A: Uneven light and dark cannot be confirmed

[0197] B: Slight unevenness is visible

[0198] C: Slight unevenness in shading is clearly visible.

[0199] D: Uneven color density is visible over a large area.

[0200] 2.4. Image quality (visual legibility)

[0201] The recorded material obtained as described above was placed on black paper, and the image was visually observed for ease of recognition, and the visibility was evaluated according to the following evaluation criteria. It should be noted that if the amount of white ink attached is small, the image will not be hidden enough, and the black color of the underlying black paper will be visible, making it difficult to visually recognize.

[0202] Evaluation Criteria

[0203] A: Easy to identify visually.

[0204] B: Looks slightly black, but is easy to identify visually.

[0205] C: Appears black but can be visually identified.

[0206] D: Appears black and difficult to identify visually.

[0207] E: Looks black and is very difficult to identify visually.

[0208] 2.5. Image quality (OD value)

[0209] The solid image of the recorded object obtained as described above was measured for OD value under the following measurement conditions using a colorimeter (i1Pro2, manufactured by X-reite Co., Ltd.), and the color development was evaluated according to the following evaluation criteria.

[0210] Measurement conditions

[0211] D50 light source, state T, standard observer 2°, background: white paper

[0212] Evaluation Criteria

[0213] A: OD value is above 1.0

[0214] B: OD value is 0.8 or more and less than 1.0

[0215] C: OD value is 0.6 or more and less than 0.8

[0216] D: OD value is 0.4 or more and less than 0.6

[0217] E: OD value is less than 0.4

[0218] 2.6. Productivity

[0219] The productivity was evaluated according to the following evaluation criteria based on the number of passes required to record a portion of the recording area whose length in the conveyance direction of the recording medium is the length of one sub-scanning.

[0220] Evaluation Criteria

[0221] A: 4 strokes or less

[0222] B: 5-6 strokes

[0223] C: 7-8 strokes

[0224] D: 9 strokes or more

[0225]

Table 2

[0226]

[0227]

Table 3

[0228]

[0229]

Table 4

[0230]

[0231] 3. Evaluation results

[0232] As described above, according to the comparison between the examples and the comparative examples, any of the examples in which the white ink and the non-white ink were recorded by simultaneous ejection and a single drying step was performed had excellent image quality (uneven density) and excellent productivity.

[0233] On the other hand, all the other comparative examples were inferior in image quality (uneven shading) and productivity.

[0234] Comparison of Examples 1 and 14 to 17 shows that the smaller the adhesion ratio (white / non-white), the better the image quality (OD value) or image quality (uneven shading), and the larger the adhesion ratio, the better the image quality (visibility).

[0235] According to the comparison of Examples 1, 3, and 9, when the content of the organic solvent below 200°C contained in the ink is high, the image quality and abrasion resistance are more excellent, and when the content is low, the ejection stability is more excellent. In addition, when the organic solvent contained in the ink includes an organic solvent below 200°C and an organic solvent above 200°C, the image quality, abrasion resistance, ejection stability, etc. are all excellent in a balanced manner.

[0236] Comparison among Examples 1, 8, and 10 shows that when the content of the organic solvent in the ink is small, image quality and the like are more excellent, and when the content is large, ejection stability and the like are more excellent.

[0237] Comparative Examples 1 to 3 did not perform the primary drying step, and the image quality (uneven density) was poor. In addition, the image quality (OD value) also tended to be reduced.

[0238] Comparative Examples 4 to 6 are examples in which white ink and non-white ink are not ejected simultaneously and recording is performed in a layered manner. Although image quality problems such as uneven density are less likely to occur, the recording speed is poor. In contrast, the productivity of the example is excellent.

[0239] Reference Example 7 did not use white ink and had poor image quality (visibility).

[0240] Reference Example 8 did not use non-white ink and had poor image quality (OD value).

Claims

1. A recording method, characterized in that: The recording method comprises: A white ink attaching step of ejecting a white ink composition containing a white color material from a white ink ejecting head and attaching the composition to a recording medium; A non-white ink attaching step of ejecting a non-white ink composition containing a non-white color material from a non-white ink ejecting head and attaching the non-white ink composition to a recording medium; as well as In a primary drying step, the white ink composition and the non-white ink composition attached to the recording medium are heated by a drying mechanism. The white ink nozzle and the non-white ink nozzle are mounted on a carriage. When the nozzle array of the white ink ejection head ejecting the white ink composition in the main scanning and the nozzle array of the non-white ink ejection head ejecting the non-white ink composition in the main scanning are projected in the main scanning direction, they have an overlapping portion in a direction intersecting the main scanning direction. In the white ink attachment process and the non-white ink attachment process in which main scanning is performed simultaneously, multiple main scans are performed, and the white ink composition and the non-white ink composition are attached to the same scanning area of ​​the recording medium by the same main scan in the overlapping part to form a single ink layer containing the white ink composition and the non-white ink composition. In the main scan, the ink nozzle is moved relative to the recording medium while the ink composition is ejected and attached to the recording medium.

2. The recording method according to claim 1, characterized in that In the primary drying step, either heating or air supply is performed.

3. The recording method according to claim 1, characterized in that In the primary drying process, air is supplied. The wind speed of the air supply is 0.5 to 5 m / s.

4. The recording method according to claim 1, characterized in that: The surface temperature of the recording medium in the primary drying process is 35 to 60°C.

5. The recording method according to claim 1, characterized in that The main scanning is performed a plurality of times on the same area of ​​the recording medium.

6. The recording method according to claim 1, characterized in that: In the region of the recording medium to which the white ink composition and the non-white ink composition are attached, in the region where the non-white ink composition is attached in the largest amount, a ratio A of the amount of the white ink composition attached relative to 100% by mass of the amount of the non-white ink composition attached is 80% by mass or less.

7. The recording method according to claim 1, characterized in that: In the area of ​​the recording medium to which the white ink composition and the non-white ink composition are attached, the maximum amount of the white ink composition attached is 10 mg / inch 2 the following.

8. The recording method according to claim 1, characterized in that: The content of the white color material is 8% by mass or more based on the total amount of the white ink composition.

9. The recording method according to claim 1, characterized in that: The white ink composition comprises an organic solvent, The content of the organic solvent having a normal boiling point of less than 200° C. in the organic solvent is 50% by mass or more relative to the total amount of the organic solvent.

10. The recording method according to claim 1, characterized in that: The white ink composition includes a dual-end alkanediol having a carbon number of 3 to 5 as an organic solvent.

11. The recording method according to claim 1, characterized in that: The white ink composition comprises an organic solvent, The maximum value of the normal boiling point of the organic solvent is 250°C.

12. The recording method according to claim 1, characterized in that: The white ink composition comprises an organic solvent, The organic solvent includes an organic solvent having a normal boiling point of lower than 200° C. and an organic solvent having a normal boiling point of higher than 200° C.

13. The recording method according to claim 1, characterized in that: The white ink composition and the non-white ink composition are respectively water-based ink compositions or respectively solvent-based ink compositions.

14. The recording method according to claim 13, characterized in that: The white ink composition and the non-white ink composition are respectively the water-based ink composition, The content of the organic solvent in the white ink composition and the non-white ink composition is 30% by mass or less, respectively.

15. The recording method according to any one of claims 1 to 13, characterized in that: The recording medium is a low-absorption recording medium or a non-absorption recording medium, The low-absorption recording medium or the non-absorption recording medium refers to the recording medium that is formed from the contact to 30 msec in the Bristol method. 1 / 2 The water absorption is 10mL / m 2 The following recording media.

16. A recording device, characterized in that: The recording device comprises: A white ink jet head ejects a white ink composition containing a white color material and deposits the white ink composition onto a recording medium; A non-white ink jet head, which jets a non-white ink composition containing a non-white color material and attaches it to the recording medium; a drying mechanism for drying the white ink composition and the non-white ink composition attached to the recording medium; and a control unit for controlling recording by using the white ink head and the non-white ink head, The recording device performs recording by the recording method according to any one of claims 1 to 15.

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