Recording method and recording device

Abstract

To provide a recording method capable of stably discharging an ink composition in an inkjet method, while capable of producing a recorded matter having an image excellent in scratch resistance and difficult to cause a so-called uneven agglomeration in which a plurality of droplets of the ink composition discharged on a recording medium agglomerate to induce a deterioration of an image quality, and also to provide a recording device capable of favorably executing the recording method.SOLUTION: A recording method includes: an adhesion step of discharging an ink composition from an inkjet head to adhere onto a recording medium; and a primary heating step of heating the ink composition adhered onto the recording medium at the adhesion step. The ink composition is an aqueous ink containing an organic compound having a standard boiling point of 280°C or lower, being solid at 25°C with a solubility to water at 25°C being 50 [g / water 100 g] or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a recording method and a recording apparatus. [Background technology]

[0002] Inkjet recording methods are widely used in which an ink composition is ejected as droplets from very fine nozzles and the droplets are deposited on a recording medium to form an image. Compared to other recording methods, this recording method has advantages such as the ability to obtain high-resolution images even with an apparatus having a simple configuration.

[0003]

[0003] Inkjet recording methods are also being considered for use in, for example, sign printing and high-speed label printing. When recording images on recording media with low ink absorption, such as art paper or coated paper, or on recording media with no ink absorption, such as plastic film, the use of aqueous ink compositions is being considered from the perspective of the global environment, and it is known that aqueous ink compositions contain wax in order to improve the abrasion resistance of recorded materials.

[0004] Therefore, for example, in order to improve the abrasion resistance of an image when recording on a recording medium using an aqueous ink composition, it has been proposed to use in combination an aqueous ink composition containing two types of wax and a reaction liquid containing an aggregating agent that aggregates the components of the ink composition (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2018-154014 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the above-described method, the ejection stability of the ink composition when used in an inkjet method is likely to decrease, and a problem of so-called aggregation unevenness is likely to occur, in which multiple droplets of the ink composition ejected onto a recording medium gather together, causing a decrease in image quality.Furthermore, there are problems such as poor ejection stability and poor abrasion resistance. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and can be realized as the following application examples.

[0008] A recording method according to an application example of the present invention includes: a deposition step of ejecting an ink composition from an inkjet head and depositing it on a recording medium; a primary heating step of heating the ink composition adhered to the recording medium in the adhesion step, The ink composition is a water-based ink containing an organic compound that has a normal boiling point of 280°C or less, is solid at 25°C, and has a solubility in water at 25°C of 50 [g / 100g water] or more.

[0009] In a recording method according to another application example of the present invention, the normal boiling point of the organic compound is 160°C or higher and 280°C or lower.

[0010] In a recording method according to another application example of the present invention, the content of the organic compound in the ink composition is 2.0% by mass or more and 20.0% by mass or less.

[0011] In a recording method according to another application example of the present invention, the melting point of the organic compound is higher than 25°C and 150°C or lower.

[0012] In a recording method according to another application example of the present invention, the organic compound is at least one selected from the group consisting of diols having an aliphatic skeleton with a branched structure, diols having a cyclic structure, and cyclic amides.

[0013] In a recording method according to another application example of the present invention, the organic compound is at least one selected from neopentyl glycol, 1,2-cyclohexanediol, pinacol, ε-caprolactam, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, and 2,5-dimethyl-2,5-hexanediol.

[0014] In a recording method according to another application example of the present invention, the ink composition contains, as an organic solvent, a polyol that has a normal boiling point of 160°C or higher and is liquid at 25°C.

[0015] In a recording method according to another application example of the present invention, the ink composition contains a silicone surfactant having an HLB value of 10 or less.

[0016] In a recording method according to another application example of the present invention, the surface temperature of the recording medium when the ink composition is heated in the primary heating step is 28° C. or higher and 50° C. or lower.

[0017] In a recording method according to another application example of the present invention, the number of main scans over the same scanning area of ​​the recording medium is 1 to 10.

[0018] In a recording method according to another application example of the present invention, the inkjet head includes a circulation mechanism for circulating the ink composition.

[0019] Moreover, a recording method according to another application example of the present invention includes a secondary heating step of further heating the recording medium after the primary heating step.

[0020] In a recording method according to another application example of the present invention, the recording medium is a low-absorbency recording medium or a non-absorbency recording medium.

[0021] Furthermore, a recording apparatus according to an application example of the present invention includes: a primary heating unit that heats a recording medium in a primary heating step; and an inkjet head that ejects onto the recording medium heated by the primary heating means an aqueous ink containing an organic compound that has a normal boiling point of 280°C or less, is solid at 25°C, and has a solubility in water at 25°C of 50 [g / 100g water] or more, and recording is performed using a recording method according to an application example of the present invention. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram showing the configuration of a recording apparatus according to a preferred embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the inkjet head. [Figure 3] FIG. 3 is a partial exploded perspective view of the inkjet head. [Figure 4] FIG. 4 is a cross-sectional view of a piezoelectric element. [Figure 5] FIG. 5 is an explanatory diagram of the circulation of the ink composition in the inkjet head. [Figure 6] FIG. 6 is a plan view and a cross-sectional view of the vicinity of the circulating liquid chamber in the inkjet head. [Figure 7] FIG. 7 is a perspective view showing the configuration of the inkjet head and its surroundings in the recording apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0023] Preferred embodiments of the present invention will be described in detail below. [1] Recording method First, the recording method of the present invention will be described.

[0024] The recording method of the present invention comprises a step of ejecting an ink composition from an inkjet head and depositing it on a recording medium, and a primary heating step of heating the ink composition deposited on the recording medium in the step of depositing it. The ink composition is a water-based ink containing an organic compound that has a normal boiling point of 280°C or less, is solid at 25°C, and has a solubility in water at 25°C of 50 [g / 100g water] or more.

[0025] This makes it possible to provide a recording method that can stably eject an ink composition by the inkjet method, is less likely to cause aggregation unevenness, a phenomenon in which multiple droplets of the ink composition ejected onto a recording medium gather together and cause a decrease in image quality, and that can produce recorded products having images with excellent abrasion resistance. Furthermore, the occurrence of unevenness due to the coffee stain phenomenon can be effectively prevented. As a result, the image formed can have excellent image quality. While there is also a method of using a reaction liquid together with the ink composition in the production of recorded products, i.e., in the recording method, the ink composition according to the present invention is less likely to cause aggregation unevenness and can effectively prevent the problem of aggregation unevenness. This is also advantageous for high-speed image formation and improved productivity of recorded products.

[0026] The reasons for the above-described excellent effects are believed to be as follows. Specifically, by using the specific organic compound described above, the solubility of the organic compound in the ink composition can be improved, and undesired precipitation of the organic compound in the ink composition can be effectively prevented, thereby enabling stable droplet ejection by the inkjet method. Furthermore, by including the organic compound described above, the ink composition rapidly thickens when a certain amount of water is removed in the primary heating step after ejection by the inkjet method. As a result, dots formed by the ink composition can be quickly fixed, and undesired movement of the dots formed by the ink composition on the recording medium can be effectively prevented. In other words, the pinning effect can be effectively exerted. Therefore, it is believed that the occurrence of unevenness due to aggregation or coffee staining can be effectively prevented, resulting in excellent image quality. Furthermore, since the organic compound itself has a relatively low normal boiling point, it can be relatively easily volatilized by heating, effectively preventing undesired residue in the recorded material. Furthermore, because the organic compound has a relatively low normal boiling point, it can be quickly and easily volatilized together with water by heating, effectively preventing it from unintentionally remaining in the recorded material, but even if the organic compound does remain in the recorded material, because the organic compound is solid at room temperature, it effectively prevents the recorded image from being disturbed by friction, etc. Therefore, it is possible to provide the recorded material with excellent abrasion resistance, and image disturbance is unlikely to occur even with short-term heat treatment, etc., which is thought to be advantageous for high-speed image formation and improved productivity of recorded materials.

[0027] On the other hand, if the above conditions are not met, satisfactory results will not be obtained. For example, if an organic compound with a normal boiling point exceeding 280°C is used instead of an organic compound satisfying the above conditions, it becomes difficult to sufficiently volatilize the organic compound from the ink composition applied to a recording medium, resulting in poor abrasion resistance of the recorded material. Furthermore, if an attempt is made to sufficiently remove the organic compound, productivity of the recorded material will be significantly reduced.

[0028] Furthermore, if an organic compound that is liquid at 25°C is used instead of an organic compound that satisfies the above conditions, it becomes difficult to thicken the compound in a short time after it is applied to the recording medium, and unevenness due to aggregation and the coffee stain phenomenon becomes more pronounced, making it difficult to form images with sufficiently high quality.

[0029] Furthermore, if an organic compound having a solubility in water at 25°C of less than 50 [g / 100 g water] is used instead of an organic compound satisfying the above conditions, it becomes difficult to achieve sufficiently excellent solubility and dissolution stability of the organic compound in the ink composition, and the ejection stability by the inkjet method, storage stability of the ink composition, etc. are significantly reduced.

[0030] In the following explanation, an organic compound that has a normal boiling point of 280°C or less, is solid at 25°C, and has a solubility in water at 25°C of 50 [g / 100g water] or more is also referred to as a "specific organic compound."

[0031] [1-1] Adhesion process In the deposition step, the ink composition is ejected from an inkjet head and deposited on a recording medium.

[0032] The ink composition will be described in detail later. In this step, a plurality of types of ink compositions may be used.

[0033] As an inkjet method for ejecting an ink composition from an inkjet head, for example, a piezo method or a method in which the ink is ejected by bubbles generated by heating the composition to be ejected can be used. However, the piezo method is preferred from the viewpoint of preventing deterioration of the components of the ink composition.

[0034] Any material may be used as the recording medium, including, for example, ordinary paper, paper specifically for inkjet printing, plastic materials, metals, ceramics, wood, shells, natural and synthetic fibers such as cotton, polyester, and wool, and nonwoven fabrics.

[0035] In particular, in the present invention, a low-absorbency recording medium or a non-absorbency recording medium can be suitably used as the recording medium.

[0036] In the past, when a low-absorbency recording medium or a non-absorbency recording medium was used as the recording medium, the problem of image quality degradation due to the above-mentioned uneven aggregation etc. occurred more significantly, but in the present invention, the occurrence of the above-mentioned problem can be sufficiently prevented even when a low-absorbency recording medium or a non-absorbency recording medium is used as the recording medium. In other words, when a low-absorbency recording medium or a non-absorbency recording medium is used as the recording medium, the effects of the present invention are more significantly exhibited.

[0037] In this specification, the term "low absorbency recording medium or non-absorbency recording medium" refers to a recording medium that is "a recording medium that is capable of being absorbed within 30 msec from the start of contact in the Bristow method." 1 / 2 Water absorption up to 10mL / m 2 The following recording medium is shown. The Bristow method is the most widely used method for measuring liquid absorption in a short period of time, and is also adopted by the Japan Pulp and Paper Technical Association (JAPAN TAPPI). Details of the test method are described in Standard No. 51 "Paper and paperboard - Liquid absorbency test method - Bristow method" of the "JAPAN TAPPI Paper and Pulp Test Method 2000 Edition."

[0038] Non-absorbent recording media include, for example, plastic films that have not been surface-treated for inkjet printing, i.e., that do not have an ink-absorbing layer, and substrates such as paper coated with plastic or with a plastic film adhered thereto. Examples of plastics include, but are not limited to, polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene. Low-absorbent recording media include, for example, printing paper such as art paper, coated paper, and matte paper. Also included is what is called coated paper.

[0039] The shape of the recording medium is not particularly limited, and may be any shape such as a sheet.

[0040] The number of main scans for the same scanning area of ​​the recording medium in this process is at least 1, and preferably no more than 20. Furthermore, it is preferably 2 to 16 times, more preferably 3 to 14 times, preferably 4 to 10 times, more preferably 4 to 7 times, and even more preferably 4 to 5 times.

[0041] This makes it possible to more effectively prevent the occurrence of aggregation unevenness and the like, to improve the image quality of the recorded portion, and to improve the abrasion resistance of the recorded matter, and also to improve the productivity of the recorded matter.

[0042] The number of times the main scan is performed on the same scanning area is also called the number of passes. The number of times the main scan is performed on the same scanning area will be described in detail later.

[0043] When the number of main scans over the same scanning area is small, the printing speed can be increased, which is preferable, but on the other hand, the amount of ink deposited over the same main scanning area in one main scan tends to be large, which makes aggregation unevenness more likely to occur, but according to this embodiment, aggregation unevenness can be reduced, which is preferable.

[0044] In addition, in this step, the inkjet head that ejects the ink composition may be equipped with a circulation mechanism that circulates the ink composition.

[0045] In an inkjet method using an inkjet head, when the ink composition dries inside the inkjet head, it solidifies and causes the generation of foreign matter, which may result in poor ejection of the ink composition. However, by providing a circulation mechanism, foreign matter is less likely to be generated, and even if foreign matter is generated, the foreign matter can be redissolved, making it possible to more effectively prevent poor ejection. The recording device equipped with the inkjet head will be described in detail later.

[0046] [1-2] Primary heating process In the primary heating step, the ink composition that has been applied to the recording medium in the above-described application step is heated.

[0047] This makes it possible to remove at least a portion of the liquid components, such as water, contained in the ink composition that has adhered to the recording medium, and to suitably suppress the flow of the ink composition.

[0048] In the primary heating step, ink is applied to a heated recording medium or the ink is heated soon after the ink is applied to the recording medium.

[0049] In the primary heating step, it is preferable to start heating the droplets of the ink composition within 0.5 seconds at the latest after the droplets have adhered to the recording medium.

[0050] The heating in the primary heating step can be carried out using various heating mechanisms, such as a conduction type, a radiation type, or an air blowing type.

[0051] The surface temperature of the recording medium when the ink composition is heated in the primary heating step is not particularly limited, but is preferably from 28° C. to 50° C., more preferably from 30° C. to 48° C., even more preferably from 32° C. to 46° C., still more preferably from 33° C. to 40° C., and even more preferably from 34° C. to 38° C.

[0052] When ink is applied to a heated recording medium, the temperature is also the surface temperature of the recording medium when the ink is applied.

[0053] This makes it possible to more reliably prevent the inkjet head that ejects the ink composition from drying out, while more efficiently thickening the ink composition applied to the recording medium and more effectively preventing the occurrence of aggregation unevenness, etc. In addition, the heating conditions in the secondary heating step described below can be alleviated, which is preferable overall from the viewpoints of energy saving and productivity of recorded matter.

[0054] In addition, when the temperature fluctuates during the primary heating step, the maximum surface temperature of the recording medium during the primary heating step is used as the surface temperature of the recording medium.

[0055] The heating time of the recording medium in the primary heating step is preferably from 0.5 seconds to 200 seconds, and more preferably from 1 second to 100 seconds.

[0056] [1-3] Secondary heating process The recording method of the present invention may further include a secondary heating step of further heating the recording medium after the primary heating step. The secondary heating step is also called a post-heating step.

[0057] This effectively prevents the volatile components and specific organic compounds contained in the ink composition applied to the recorded matter from unintentionally remaining, thereby improving the abrasion resistance and reliability of the final recorded matter. Furthermore, when the ink composition contains a resin as described below, the recorded part can be effectively flattened, improving the abrasion resistance of the recorded matter and also improving the glossiness of the image.

[0058] The second heating step is carried out after the first heating step is completed, and it is preferable that the second heating step starts heating a certain portion of the recording medium more than 0.5 seconds after the ink composition has been completely deposited on that portion.

[0059] The surface temperature of the recording medium when the ink composition is heated in the secondary heating step is not particularly limited, but is preferably higher than the surface temperature of the recording medium in the primary heating step, and more specifically, is preferably 40°C or higher, more preferably 50°C or higher and 120°C or lower, even more preferably 65°C or higher and 100°C or lower, and even more preferably 70°C or higher and 90°C or lower.

[0060] This allows the effects of the secondary heating step to be more pronounced, and also improves the productivity of the recorded matter, which is also preferable from the viewpoint of energy saving and preventing undesired deterioration and degeneration of the constituent materials of the recorded matter.

[0061] In addition, when the temperature fluctuates during the secondary heating step, the maximum surface temperature of the recording medium during the secondary heating step is used as the surface temperature of the recording medium.

[0062] The heating time of the recording medium in the secondary heating step is preferably from 1 second to 300 seconds, more preferably from 3 seconds to 200 seconds.

[0063] The heating in the secondary heating step can be performed using various heating mechanisms, such as a conduction type, a radiation type, or an air blowing type.

[0064] [1-4] Other processes The recording method of the present invention may further include steps other than those described above.

[0065] For example, a cooling step of cooling the recording medium may be performed after the primary heating step or the secondary heating step.

[0066] This makes it possible to effectively prevent stickiness of the recorded portion due to the ink composition, etc. Furthermore, even when the printed surface of the produced recorded matter comes into contact with another member or with another recorded matter, it is possible to effectively prevent unintended disturbance of the recorded matter, etc.

[0067] When the cooling step is carried out, the surface temperature of the recording medium at the end of the cooling step is preferably 30°C or lower, and more preferably -20°C or higher and 25°C or lower.

[0068] [1-5] Ink composition Next, the ink composition used in the recording method of the present invention will be described in detail. In the following description, the ink composition will also be simply referred to as "ink."

[0069] The ink composition used in the present invention is a water-based ink containing a specific organic compound that has a normal boiling point of 280°C or less, is solid at 25°C, and has a solubility in water at 25°C of 50 [g / 100g water] or more.

[0070] In this specification, the term "water-based" refers to an ink composition in which the water content is 40% by mass or less relative to the total mass of the ink composition. The water content is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more and 98% by mass or less.

[0071] Furthermore, the proportion of water among all liquid components contained in the ink composition, more specifically, the proportion of water among all components that are liquid by themselves in an environment of 1 atmosphere and 25°C, is preferably 50 mass% or more, and more preferably 60 mass% or more.

[0072] [1-5-1]Specific organic compounds The ink composition contains a specific organic compound that has a normal boiling point of 280°C or less, is solid at 25°C, and has a solubility in water at 25°C of 50 [g / 100g water] or more.

[0073] The ink composition is a water-based ink and usually contains a water content that is sufficiently high relative to the content of the specific organic compound, so that the specific organic compound that has a very high solubility in water as described above is contained in the ink composition in a dissolved state.

[0074] The normal boiling point of the specific organic compound, i.e., the boiling point under 1 atmospheric pressure, may be 280°C or lower, but is preferably 160°C or higher and 280°C or lower, more preferably 180°C or higher and 275°C or lower, even more preferably 200°C or higher and 270°C or lower, and even more preferably 220°C or higher and 270°C or lower. This makes the above-mentioned effects more pronounced.

[0075] When the ink composition contains multiple types of specific organic compounds, it is preferable that at least one of the specific organic compounds contained in the ink composition satisfies the above-mentioned normal boiling point condition, it is more preferable that the specific organic compound with the highest content satisfies the above-mentioned normal boiling point condition, and it is even more preferable that all of the specific organic compounds contained in the ink composition satisfy the above-mentioned normal boiling point condition. This makes the above-mentioned effects more pronounced.

[0076] The solubility of the specific organic compound in water at 25°C may be 50 [g / 100g water] or more, preferably 60 [g / 100g water] or more, more preferably 70 [g / 100g water] or more, even more preferably 80 [g / 100g water] or more, and even more preferably 100 [g / 100g water] or more. This makes the above-mentioned effects more pronounced.

[0077] The solubility is determined as follows: A predetermined amount of compound is mixed with 100 g of water in an environment of 25°C and stirred for 30 minutes. If there is no residue left after stirring, it is determined that the compound is dissolved. When a predetermined amount of compound is mixed with 100 g of water in this way, the largest amount of the predetermined amount that is determined to be dissolved is taken as the solubility.

[0078] When a specific organic compound dissolves in water at any ratio, the solubility of the specific organic compound in water is infinite.

[0079] The melting point of the specific organic compound is preferably higher than 25°C and not higher than 150°C, more preferably from 45°C to 140°C, even more preferably from 60°C to 130°C, still more preferably from 65°C to 110°C, and even more preferably from 70°C to 100°C. This makes the above-mentioned effects more pronounced.

[0080] The vapor pressure of the specific organic compound at 25°C is preferably 10 Pa or more. This makes the above-mentioned effects more pronounced.

[0081] The molecular weight of the specific organic compound is preferably 500 or less, more preferably 300 or less, and even more preferably 50 or more and 200 or less. This makes the above-mentioned effects more pronounced.

[0082] The specific organic compound is preferably a nonionic compound. This makes the above-mentioned effects more pronounced.

[0083] The specific organic compound may be any organic compound that is solid at 25°C and satisfies the above-mentioned conditions of normal boiling point and solubility in water at 25°C, but it is preferable that it satisfies the following conditions. That is, it is preferably a diol or a cyclic amide. Alternatively, the specific organic compound is preferably a compound having an aliphatic skeleton or a compound having a cyclic structure. As a compound having an aliphatic skeleton, a compound having an acyclic aliphatic skeleton is preferred. In the case of a compound having a cyclic structure, the cyclic structure is preferably an alicyclic structure, a cyclic amide structure, or the like.

[0084] Furthermore, the specific organic compound is preferably at least one selected from the group consisting of compounds having an aliphatic skeleton with a branched structure and compounds having a cyclic structure.

[0085] In particular, it is more preferable to use at least one selected from the group consisting of diols having an aliphatic skeleton with a branched structure, diols having a cyclic structure, and cyclic amides. This makes the above-mentioned effects more pronounced.

[0086] Examples of specific organic compounds that satisfy the above-mentioned conditions regarding chemical structure include neopentyl glycol, 1,2-cyclohexanediol, pinacol, ε-caprolactam, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, and 2,5-dimethyl-2,5-hexanediol. In particular, at least one selected from neopentyl glycol, 1,2-cyclohexanediol, pinacol, ε-caprolactam, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, and 2,5-dimethyl-2,5-hexanediol is preferred, and at least one of neopentyl glycol and ε-caprolactam is more preferred. This makes the above-mentioned effects more pronounced.

[0087] The content of the specific organic compound in the ink composition is preferably 1% by mass or more and 25% by mass or less, more preferably 2.0% by mass or more and 20.0% by mass or less, even more preferably 3.0% by mass or more and 18.0% by mass or less, and even more preferably 5.0% by mass or more and 15.0% by mass or less. This makes the above-mentioned effects more pronounced.

[0088] [1-5-2]Water The ink composition is a water-based ink and contains water as a constituent component.

[0089] In the ink composition, water functions as a solvent that dissolves the specific organic compound described above, and is also an important component in terms of improving the ejection stability of the ink composition when used in an inkjet method, the drying of the ink composition on a recording medium, etc. Furthermore, using water as a solvent that dissolves the specific organic compound is advantageous from the standpoints of environmental conservation and the safety of workers producing the ink composition and workers producing the recorded material.

[0090] The water content in the ink composition is preferably 45% by mass or more, more preferably 50.0% by mass to 95.0% by mass, even more preferably 65.0% by mass to 93.0% by mass, and even more preferably 80.0% by mass to 90.0% by mass.

[0091] [1-5-3] Coloring materials The ink composition usually contains a colorant.

[0092] As the coloring material, for example, various dyes and various pigments can be used. Furthermore, as the coloring material, for example, a fluorescent substance or the like can be used which is not visible under normal circumstances but makes it possible to identify the recorded portion formed using the ink composition under ultraviolet irradiation conditions or the like.

[0093] In particular, pigments are preferably used because they are resistant to fading due to light, gas, etc. Images formed on recording media using pigments not only have excellent image quality, but also have excellent water resistance, gas resistance, light resistance, etc., and good storage stability. This property is particularly noticeable when images are formed on recording media that are non-ink-absorbent or have low ink absorption.

[0094] Examples of pigments include inorganic pigments and organic pigments.

[0095] As the inorganic pigment, for example, titanium oxide and iron oxide, as well as carbon black produced by known methods such as the contact method, furnace method, and thermal method can be used.

[0096] As the organic pigment, for example, azo pigments, polycyclic pigments, nitro pigments, nitroso pigments, aniline black, etc. can be used.

[0097] Examples of azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc. Examples of polycyclic pigments include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinophthalone pigments, etc.

[0098] An example of the black pigment is carbon black. Examples of white pigments include white inorganic pigments such as CI Pigment White 6, 18, and 21, titanium oxide, zinc oxide, zinc sulfide, antimony oxide, magnesium oxide, and zirconium oxide. In addition to these white inorganic pigments, white organic pigments such as white hollow resin particles and polymer particles can also be used.

[0099] Other chromatic pigments include CI Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 16, 17, 24, 34, 35, 37, 53, 55, 65, 73, 74, 75, 81, 83, 93, 94, 95, 97, 98, 99, 108, 109, 110, 113, 114, 117, 120, 124, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 1 3, 138, 139, 147, 151, 153, 154, 167, 172, 180, CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 40, 41, 42, 48(Ca), 48(Mn), 57(Ca), 57:1, 88, 1 12, 114, 122, 123, 144, 146, 149, 150, 166, 168, 170, 171, 175, 176, 177, 178, 179, 184, 185, 187, 202, 209, 219, 224, 245, CI Pigment Violet 19, 23, 32, 33, 36, 38, 43, 50, CI Pigment Blue 1, 2, 3, 15, Examples include 15:1, 15:2, 15:3, 15:34, 15:4, 16, 18, 22, 25, 60, 65, 66, CI Bat Blue 4, 60, CI Pigment Green 7, 10, CI Pigment Brown 3, 5, 25, 26, CI Pigment Orange 1, 2, 5, 7, 13, 14, 15, 16, 24, 34, 36, 38, 40, 43, and 63.

[0100] Examples of pearl pigments include pigments having pearlescent or interference luster, such as titanium dioxide-coated mica, fish scale foil, and bismuth oxychloride.

[0101] The metallic pigment is not particularly limited, but examples thereof include particles composed of a single element or an alloy of aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, copper, etc.

[0102] The content of the colorant in the ink composition is preferably 0.5% by mass to 10.0% by mass, more preferably 1.0% by mass to 7.0% by mass, and even more preferably 3.0% by mass to 6.0% by mass.

[0103] This makes it possible to, for example, ensure that the color density of the image formed on the recording medium is sufficiently high, while also improving the ejection stability by an ink jet method, storage stability, and the like of the ink composition.

[0104] When the ink composition is a clear ink, the ink composition does not need to contain a coloring material.

[0105] [1-5-4] Organic solvents The ink composition may contain an organic solvent that is liquid at 25°C by itself.

[0106] By including an organic solvent in the ink composition, clogging in an inkjet head can be more effectively prevented. Furthermore, by including an organic solvent in the ink composition, the ink composition ejected onto a recording medium dries well, and images with better image quality and abrasion resistance can be obtained.

[0107] The organic solvent used in the ink composition is preferably a water-soluble organic solvent. This can improve the moisture retention of the ink composition and more effectively prevent the solid content of the ink composition from unintentionally precipitating due to drying in an inkjet head or the like. Furthermore, the viscosity of the ink composition can be more suitably adjusted. This further improves the ejection stability of the ink composition when used in an inkjet method.

[0108] The water-soluble organic solvent may be any organic solvent that is soluble in water, and for example, an organic solvent having a solubility in water at 25° C. of 10 [g / 100 g water] or more can be suitably used.

[0109] The boiling point of the water-soluble organic solvent at 1 atmospheric pressure, i.e., the normal boiling point, is preferably 150°C or higher and 350°C or lower, and more preferably 160°C or higher and 280°C or lower.

[0110] This can further improve the moisture retention of the ink composition, and more effectively prevent the solid content of the ink composition from unintentionally precipitating due to drying in an inkjet head or the like. As a result, the ejection stability of the ink composition when used in an inkjet method can be further improved. Furthermore, after the ink composition is ejected, it can be relatively easily volatilized as needed, and more effectively prevent the water-soluble organic solvent from unintentionally remaining in the recorded matter produced.

[0111] The water-soluble organic solvent is not particularly limited, but examples thereof include polyols, nitrogen-containing solvents, esters, glycol ethers, and cyclic esters.

[0112] Polyols are compounds having two or more hydroxyl groups in the molecule, and the number of hydroxyl groups in the molecule is preferably 2 or more and 4 or less, more preferably 2 or 3.

[0113] Examples of polyols include 1,2-alkanediols such as ethylene glycol, propylene glycol, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, and 1,2-octanediol; alkanediols such as 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and 1,6-hexanediol; diethylene glycol; triethylene glycol; Examples of suitable glycerides include dipropylene glycol, 2-ethyl-2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 3-methyl-1,3-butanediol, 2-ethyl-1,3-hexanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, trimethylolpropane, and glycerin.

[0114] Among polyols, preferred are alkanediols having from 2 to 10 carbon atoms and condensates in which hydroxyl groups of alkanediols having from 2 to 10 carbon atoms are condensed intermolecularly. In the case of condensates, the number of condensations is preferably from 2 to 4. The alkanediol is more preferably an alkanediol having from 3 to 6 carbon atoms, even more preferably an alkanediol having from 3 to 5 carbon atoms, and particularly preferably an alkanediol having from 3 to 4 carbon atoms.

[0115] Examples of nitrogen-containing solvents include amide solvents. Examples of amide solvents include cyclic amide solvents and non-cyclic amide solvents. Examples of cyclic amide solvents include pyrrolidones. Examples of non-cyclic amide solvents include alkoxyalkylamides.

[0116] Examples of cyclic amide solvents include pyrrolidones such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-pyrrolidone, 1-(2-hydroxyethyl)-2-pyrrolidone, N-butyl-2-pyrrolidone, and 5-methyl-2-pyrrolidone.

[0117] Examples of the acyclic amide solvents include alkoxyalkylamides, such as 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, and 3-n-butoxy-N,N-methylethylpropionamide. amide, 3-n-propoxy-N,N-dimethylpropionamide, 3-n-propoxy-N,N-diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, 3-iso-propoxy-N,N-dimethylpropionamide, 3-iso-propoxy-N,N-diethylpropionamide, 3-iso-propoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, 3-tert-butoxy-N,N-methylethylpropionamide, and the like.

[0118] Examples of esters include glycol monoacetates such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and methoxybutyl acetate; Examples of the glycol diesters include glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate, ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, and dipropylene glycol acetate propionate.

[0119] Examples of glycol ethers include monoethers and diethers of alkylene glycols. Specific examples of glycol ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol alkylene glycol monoalkyl ethers such as glycol monobutyl ether; and alkylene glycol dialkyl ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether.

[0120] Examples of cyclic esters include lactones such as β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, γ-hexanolactone, δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ-nonalactone, ε-nonalactone, and ε-decanolactone; and compounds in which the hydrogen atom of the methylene group adjacent to the carbonyl group in these compounds is substituted with an alkyl group having 1 to 4 carbon atoms.

[0121] The content of the organic solvent in the ink composition is preferably from 1.0% to 40.0% by mass, more preferably from 5.0% to 35.0% by mass, even more preferably from 8.0% to 30.0% by mass, and even more preferably from 10% to 25% by mass.

[0122] The ink composition preferably contains a polyol as the organic solvent, and particularly preferably contains a polyol having a normal boiling point of 160° C. or higher.

[0123] This makes it possible to further improve the moisture retention of the ink composition and more effectively prevent the solid content of the ink composition from unintentionally precipitating due to drying in an inkjet head or the like. Furthermore, the viscosity of the ink composition can be more suitably adjusted. As a result, the ejection stability of the ink composition when used in an inkjet method can be further improved.

[0124] Furthermore, when the ink composition contains an organic solvent, particularly a polyol, the ink composition can have excellent ejection stability when used in an inkjet method, and therefore the ink composition has excellent ejection stability even when the inkjet head does not have a circulation mechanism, which is preferable.

[0125] When the ink composition contains the above-mentioned polyols as an organic solvent, the normal boiling point of the polyols is preferably 160°C or higher and 280°C or lower, more preferably 170°C or higher and 250°C or lower, and even more preferably 180°C or higher and 230°C or lower.

[0126] When the ink composition contains a polyol as an organic solvent, the content of the polyol in the ink composition may be the preferred content of the organic solvent described above, and is preferably from 0.5% to 25.0% by mass, more preferably from 1.0% to 20.0% by mass, even more preferably from 3.0% to 15.0% by mass, and even more preferably from 5.0% to 12.0% by mass.

[0127] It is also preferable to set the content of polyols having a normal boiling point within the above range within the above range.

[0128] The content of the organic solvent in the ink composition is preferably 1.0% by mass or more and 26.0% by mass or less, more preferably 1.5% by mass or more and 21.0% by mass or less, and even more preferably 3.5% by mass or more and 16.0% by mass or less.

[0129] The ink composition preferably does not contain more than 1% by mass, more preferably does not contain more than 0.5% by mass, even more preferably does not contain more than 0.2% by mass, or may not contain any polyols having a normal boiling point above 280°C. Furthermore, the ink composition preferably does not contain more than 1% by mass, more preferably does not contain more than 0.5% by mass, even more preferably does not contain more than 0.2% by mass, or may not contain any organic solvents having a normal boiling point above 280°C. In these cases, excellent abrasion resistance is obtained, which is preferred.

[0130] [1-5-5] Resin The ink composition may contain a resin.

[0131] The resin has the effect of, for example, firmly fixing the solidified ink composition onto a recording medium, and is also a component that can improve the abrasion resistance of the recorded material and contributes to improving the glossiness and other image quality of the recorded material.

[0132] When the ink composition contains a resin, the resin may be in either a dissolved state or a dispersed state in the ink composition.

[0133] The resin contained in the ink composition is not particularly limited, but examples thereof include acrylic resin, vinyl acetate resin, vinyl chloride resin, butadiene resin, styrene resin, polyester resin, cross-linked acrylic resin, cross-linked styrene resin, benzoguanamine resin, phenolic resin, silicone resin, epoxy resin, urethane resin, paraffin resin, fluororesin, water-soluble resin, and copolymers of monomers constituting these resins. Examples of copolymers include, but are not particularly limited to, styrene-butadiene resin, styrene-acrylic resin, and the like. Furthermore, polymer latexes containing these resins can be used as the resin. Examples thereof include polymer latexes containing fine particles of acrylic resin, styrene-acrylic resin, styrene resin, cross-linked acrylic resin, and cross-linked styrene resin.

[0134] Acrylic resins are homopolymers or copolymers obtained by polymerizing at least acrylic monomers. Examples of acrylic monomers include (meth)acrylate, (meth)acrylic acid, acrylamide, and acrylonitrile. When the acrylic resin is a copolymer, examples of the copolymer include acrylic-vinyl resins that use vinyl monomers as other monomers, and particularly styrene-acrylic resins that use styrene as the vinyl monomer.

[0135] Among the above resins, acrylic resins, urethane resins, polyester resins, etc. are preferred because they are easily available and can be easily obtained as resins having the desired properties.

[0136] The resin content in the ink composition is preferably 0.3% by mass to 10.0% by mass, more preferably 0.5% by mass to 7.0% by mass, and even more preferably 0.7% by mass to 5.0% by mass.

[0137] This allows the ink composition to have sufficiently excellent ejection stability and the effects of including the resin as described above to be more pronounced.

[0138] [1-5-6] Wax The ink composition may contain a wax.

[0139] This makes it possible to improve the abrasion resistance of the recorded matter obtained by carrying out the recording method of the present invention.

[0140] Examples of waxes include those that dissolve in the ink composition and those that are dispersed in the form of fine particles, such as emulsions.

[0141] By using such a wax, for example, it is possible to improve the abrasion resistance of recorded matter produced using the ink composition.

[0142] The wax is not particularly limited, but examples thereof include ester waxes of higher fatty acids and higher monohydric or dihydric alcohols, paraffin wax, microcrystalline wax, polyolefin wax, and the like.

[0143] Examples of polyolefin waxes include waxes produced from olefins such as ethylene, propylene, and butylene, or their derivatives, and copolymers thereof. More specific examples include polyethylene-based waxes, polypropylene-based waxes, and polybutylene-based waxes.

[0144] When the ink composition contains wax, the wax content in the ink composition is preferably 0.1% by mass or more and 5.0% by mass or less, more preferably 0.2% by mass or more and 4.0% by mass or less, and even more preferably 0.3% by mass or more and 3.0% by mass or less.

[0145] [1-5-7] Surfactants The ink composition may contain a surfactant. Examples of the surfactant include anionic surfactants and nonionic surfactants. Examples of the nonionic surfactant include silicone-based surfactants, acetylene glycol-based surfactants, and fluorine-based surfactants.

[0146] The nonionic surfactant is preferably a silicone surfactant, and the silicone surfactant preferably has an HLB value of 12 or less, more preferably an HLB value of 1 or more and 11 or less.

[0147] The ink composition may contain a silicone surfactant having an HLB value of 10 or less.

[0148] This makes it possible to more effectively prevent the occurrence of the aforementioned aggregation unevenness, thereby improving the image quality of recorded materials. Hereinafter, silicone surfactants with an HLB value of 10 or less will also be referred to as "specific surfactants."

[0149] The HLB value of the specific surfactant may be 10 or less, preferably 1 or more and 9 or less, more preferably 2 or more and 8 or less, and even more preferably 3 or more and 7 or less. This makes the above-mentioned effects more pronounced.

[0150] Examples of commercially available products of the specific surfactant include Silface SAG005 (manufactured by Nissin Chemical Industry Co., Ltd.) and Silface SAG021 (manufactured by Nissin Chemical Industry Co., Ltd.).

[0151] Examples of anionic surfactants include carboxylic acid type, sulfonic acid type, sulfate type, and phosphate type, with sulfonic acid type being particularly preferred.

[0152] The surfactant may contain a nonionic surfactant and an anionic surfactant, which is preferable since it is more effective in reducing aggregation unevenness.

[0153] The content of the surfactant in the ink composition is preferably from 0.01% to 2.0% by mass, more preferably from 0.1% to 1.5% by mass, even more preferably from 0.3% to 1.2% by mass, and even more preferably from 0.5% to 1.0% by mass.

[0154] When the ink composition contains a specific surfactant, the content of the specific surfactant in the ink composition may be within the above range, preferably from 0.01% to 2.0% by mass, more preferably from 0.01% to 1.5% by mass, even more preferably from 0.01% to 1.2% by mass, still more preferably from 0.01% to 1.0% by mass, more preferably from 0.02% to 0.7% by mass, and even more preferably from 0.03% to 0.4% by mass.

[0155] [1-5-8] Other ingredients The ink composition may contain components other than those described above. Hereinafter, such components will also be referred to as "other components" in this section.

[0156] Examples of other components include dispersants, antifoaming agents, viscosity adjusters, pH adjusters, preservatives, mildew inhibitors, rust inhibitors, flame retardants, antioxidants, ultraviolet absorbers, oxygen absorbers, dissolution aids, penetrating agents, chelating agents, and moisturizing agents other than organic solvents.

[0157] The content of other components in the ink composition is preferably 6.0% by mass or less, and more preferably 5.0% by mass or less.

[0158] [1-5-9] Other conditions The surface tension of the ink composition at 25°C is not particularly limited, but is preferably from 20 mN / m to 60 mN / m, more preferably from 25 mN / m to 50 mN / m, and even more preferably from 30 mN / m to 40 mN / m.

[0159] This makes it more difficult for nozzles of the inkjet head to become clogged, and improves the ejection stability of the ink composition. Furthermore, even if nozzles do become clogged, recovery by capping the nozzles can be more excellent.

[0160] The surface tension can be measured by the Wilhelmy method or the Ring method using a surface tensiometer (e.g., DY-300, DY-500, DY-700, etc., manufactured by Kyowa Interface Science Co., Ltd.).

[0161] The viscosity of the ink composition at 25° C. is preferably 2 mPa·s or more and 10 mPa·s or less, and more preferably 3 mPa·s or more and 8 mPa·s or less.

[0162] This provides the ink composition with better ejection stability when subjected to an ink jet method.

[0163] The viscosity can be determined by measurement using a vibration viscometer, a rotational viscometer, a capillary viscometer, or a falling ball viscometer. For example, when using a vibration viscometer, the viscosity can be determined by measurement in accordance with JIS Z8809.

[0164] [2] Recording device Next, the recording apparatus of the present invention will be described.

[0165] The recording apparatus of the present invention includes a primary heating means for heating a recording medium in a primary heating step, and an inkjet head for ejecting onto the recording medium heated by the primary heating means an aqueous ink containing an organic compound having a normal boiling point of 280° C. or less, being solid at 25° C., and having a solubility in water at 25° C. of 50 [g / 100 g water] or more. The recording apparatus of the present invention performs recording by executing the recording method of the present invention described above.

[0166] This makes it possible to provide a recording apparatus that can stably eject an ink composition by the inkjet method, is less likely to cause aggregation unevenness, a phenomenon in which multiple droplets of the ink composition ejected onto a recording medium gather together and cause a decrease in image quality, and is capable of producing recorded products having images with excellent abrasion resistance. Furthermore, the occurrence of unevenness due to the coffee stain phenomenon can be effectively prevented. As a result, the image formed can have excellent image quality. While there are methods for producing recorded products, i.e., recording methods, in which a reaction liquid is used together with the ink composition, the present invention makes it less likely for the ink composition to cause aggregation unevenness, and can effectively prevent the problem of aggregation unevenness without necessarily using a reaction liquid. This is also advantageous for high-speed image formation and improved productivity of recorded products. The recording method of this embodiment may use a reaction liquid, although

[0167] Preferred embodiments of the recording apparatus of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a structural diagram of a recording apparatus according to a preferred embodiment of the present invention. Fig. 2 is a cross-sectional view of an inkjet head. Fig. 3 is a partially exploded perspective view of the inkjet head. Fig. 4 is a cross-sectional view of a piezoelectric element. Fig. 5 is an explanatory diagram of the circulation of an ink composition in an inkjet head. Fig. 6 is a plan view and a cross-sectional view of the vicinity of a circulating liquid chamber in an inkjet head. Fig. 7 is a perspective view showing an example of the configuration of the periphery of the inkjet head of the recording apparatus of Fig. 1.

[0168] The recording apparatus 100 is an inkjet printing apparatus that ejects an ink composition toward a recording medium M.

[0169] As shown in FIG. 1, the recording apparatus 100 includes a control unit 20, an ink composition storage container 11 that stores an ink composition, an ink composition circulation tank 12 as a sub-tank, an inkjet head 26, an IR heater 13, a platen heater 14, a curing heater 15, a cooling fan 16, a preheater 17, and a ventilation fan 18.

[0170] The ink composition stored in the ink composition storage container 11 is supplied to an ink composition circulation tank 12 serving as a sub-tank, and from there to an inkjet head 26. Although not shown in the figure, the ink composition circulation tank 12 is connected to the inkjet head 26.

[0171] 1 has only one circulation mechanism for the ink composition, which is a set of an ink composition container 11 and an ink composition circulation tank 12. However, when a plurality of types of ink compositions are used, circulation mechanisms for the ink compositions are provided according to the number of ink compositions.

[0172] The inkjet head 26 and the ink composition circulation tank 12 constitute a part of a circulation mechanism 75, which will be described in detail later.

[0173] A self-sealing valve (not shown) is provided in the flow path through which the ink composition is supplied from the ink composition circulation tank 12 to the inkjet head 26. Although not shown, a filter for capturing foreign matter is provided downstream of each of the self-sealing valves.

[0174] A portion of the ink composition supplied from the ink composition circulation tank 12 to the inkjet head 26 is ejected from the nozzle N of the inkjet head 26, and the portion not ejected from the nozzle N is returned to the ink composition circulation tank 12.

[0175] The control unit 20 includes a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and controls each element of the recording device 100 in an integrated manner.

[0176] For example, the control unit 20 controls the operation of a transport mechanism that transports the recording medium M in the Y-axis direction.

[0177] The control unit 20 also controls the operation of a movement mechanism that moves the inkjet head 26 back and forth in the X-axis direction. The X-axis direction is a direction that intersects with the Y-axis direction along which the recording medium M is transported. Typically, the X-axis direction is a direction that is perpendicular to the Y-axis direction.

[0178] The moving mechanism includes a roughly box-shaped conveying body that houses the inkjet head 26, and a conveying belt to which the conveying body is fixed.

[0179] The inkjet head 26 is a means for ejecting and depositing the ink composition onto the recording medium M. In particular, in this embodiment, the inkjet head 26 is a serial inkjet head.

[0180] The recording apparatus 100 is equipped with an IR heater 13, a platen heater 14, a preheater 17, and a ventilation fan 18 as primary heating means for performing a primary heating step of heating the ink composition adhered to the recording medium M. In the primary heating step, at least one of these may be used.

[0181] As the primary heating means, a heating mechanism such as a conduction type, such as a platen heater 14 or a preheater 17, which conducts heat from a member in contact with the recording medium to the recording medium, a radiation type, such as an IR heater 13, which emits electromagnetic waves that generate heat, or a blower type, such as a ventilation fan 18, which sends heated air to the recording medium can be used.

[0182] By using the IR heater 13, the recording medium M can be heated from the inkjet head 26 side. As a result, the inkjet head 26 is also likely to be heated at the same time, but compared to heating the recording medium M from the back side using the platen heater 14 or the like, the temperature can be increased without being affected by the thickness of the recording medium M. Furthermore, by using the platen heater 14, the recording medium M can be heated from the side opposite the inkjet head 26 side. As a result, the inkjet head 26 is relatively less likely to be heated.

[0183] The curing heater 15 is a secondary heating means that performs a secondary heating step and is provided downstream in the conveyance direction of the recording medium M from the IR heater 13 and the platen heater 14 that serve as primary heating means.

[0184] The curing heater 15 may be, for example, a conduction type, a radiation type, or an air blower type.

[0185] The recording apparatus 100 is equipped with a cooling fan 16 that performs a cooling step. After the ink composition recorded on the recording medium M is heated and dried by the curing heater 15, the recorded portion of the ink composition on the recording medium M is cooled by the cooling fan 16, thereby effectively suppressing stickiness of the recorded portion due to the ink composition. Furthermore, even if the printed surface of the produced recorded matter comes into contact with another member or with another recorded matter, unintended disturbance of the recorded portion can be effectively prevented.

[0186] The recording apparatus 100 also includes a preheater 17 that preheats the recording medium M before the ink composition ejected from the inkjet head 26 is deposited on the recording medium M. In other words, the preheater 17 is provided upstream in the transport direction of the recording medium M from the location where the ink composition is applied to the recording medium M by the inkjet head 26. This allows the primary heating step to be carried out more efficiently.

[0187] The preheater 17 may be, for example, a conduction type. In the illustrated configuration, the recording apparatus 100 is provided with a ventilation fan 18. This allows the ink composition adhered to the recording medium M to dry more efficiently.

[0188] The inkjet head 26 ejects the ink composition supplied from the ink composition circulation tank 12 from multiple nozzles N onto the recording medium M under the control of the control unit 20. Each inkjet head 26 ejects the ink composition onto the recording medium M in parallel with the transportation of the recording medium M by the transportation mechanism and the repeated reciprocation of the transportation body, thereby forming a desired image on the surface of the recording medium M. Note that a direction perpendicular to the XY plane, for example, a direction perpendicular to a plane parallel to the surface of the recording medium M, will be referred to as the Z-axis direction below. The direction in which the ink composition is ejected from each inkjet head 26 corresponds to the Z-axis direction. The Z-axis direction is typically a vertical direction.

[0189] 7, the periphery of the inkjet head 26 of the recording device 100 includes the inkjet head 26, a housing 21 that houses the inkjet head 26, a carriage 9, a platen heater 14, a carriage movement mechanism 22, a transport means 23, and a control unit 20. A nozzle row (not shown) is arranged on the underside of the inkjet head 26 along the sub-scanning direction SS.

[0190] The recording device 100 performs a main scan in which the inkjet head 26 moves in either S1 or S2 of a main scanning direction MS, ejecting an ink composition from the nozzles of the nozzle array and depositing it on the recording medium M. The recording device 100 also performs a sub-scan in which the recording medium M moves in a sub-scanning direction SS. This example recording device is a serial type recording device, and recording is performed by repeatedly and alternately performing main scans and sub-scans on the recording medium M.

[0191] If the distance the recording medium moves in the sub-scanning direction in one sub-scan is, for example, one-fourth the length of the nozzle row in the sub-scanning direction, four main scans will be performed on an area of ​​the recording medium that is the distance in the sub-scanning direction of one sub-scan. In this case, four main scans will be performed on the same scanned area of ​​the recording medium. The number of main scans performed on the same scanned area of ​​the recording medium is thus the number of main scans performed on the same scanned area of ​​the recording medium. In this example, the shorter the distance the recording medium moves in the sub-scanning direction in one sub-scan, the more main scans will be performed on the same scanned area of ​​the recording medium.

[0192] As shown in FIG. 5 and other figures, the nozzles N of the inkjet head 26 are arranged in the Y-axis direction. The nozzles N are divided into a first row L1 and a second row L2, which are arranged side by side at intervals in the X-axis direction. The first row L1 and the second row L2 are each a collection of nozzles N linearly arranged in the Y-axis direction. Note that the positions of the nozzles N in the Y-axis direction can be different between the first row L1 and the second row L2, i.e., a staggered arrangement, but for convenience, the following example illustrates a configuration in which the positions of the nozzles N in the Y-axis direction are the same between the first row L1 and the second row L2. In the inkjet head 26, a plane that passes through the central axis parallel to the Y-axis direction and is parallel to the Z-axis direction, i.e., the YZ plane, is referred to as the "center plane O" in the following description.

[0193] 2 and 3, the inkjet head 26 has a structure in which elements related to each nozzle N in the first row L1 and elements related to each nozzle N in the second row L2 are arranged symmetrically with respect to a central plane O. That is, the inkjet head 26 has a substantially common structure between a first portion P1, which is the portion on the positive side of the X-axis direction, and a second portion P2, which is the portion on the negative side of the X-axis direction, with respect to the central plane O. The multiple nozzles N in the first row L1 are formed in the first portion P1, and the multiple nozzles N in the second row L2 are formed in the second portion P2. The central plane O corresponds to the boundary surface between the first portion P1 and the second portion P2.

[0194] As shown in FIGS. 2 and 3, the inkjet head 26 includes a flow path forming section 30. The flow path forming section 30 is a structure that forms a flow path for supplying an ink composition to a plurality of nozzles N. The flow path forming section 30 has a configuration in which a first flow path substrate 32 serving as a communication plate and a second flow path substrate 34 serving as a pressure chamber forming plate are stacked together. The first flow path substrate 32 and the second flow path substrate 34 are each plate-like members that are elongated in the Y-axis direction. The second flow path substrate 34 is attached to the surface Fa of the first flow path substrate 32 on the negative side in the Z-axis direction, for example, using an adhesive.

[0195] 2, in addition to the second flow path substrate 34, a vibrating section 42, a plurality of piezoelectric elements 44, a protective member 46, and a housing section 48 are disposed on the surface Fa of the first flow path substrate 32. On the other hand, a nozzle plate 52 and a vibration absorber 54 are disposed on the positive side of the first flow path substrate 32 in the Z-axis direction, i.e., on the surface Fb opposite to the surface Fa. The elements of the inkjet head 26 are generally plate-like members that are elongated in the Y-axis direction, similar to the first flow path substrate 32 and the second flow path substrate 34, and are bonded to each other using, for example, an adhesive. The direction in which the first flow path substrate 32 and the second flow path substrate 34 are stacked, or the direction in which the first flow path substrate 32 and the nozzle plate 52 are stacked, can also be understood as the Z-axis direction.

[0196] The nozzle plate 52 is a plate-like member in which multiple nozzles N are formed. The nozzle plate 52 is attached to the surface Fb of the first flow path substrate 32 using, for example, an adhesive. Each of the multiple nozzles N is a circular through-hole that allows the ink composition to pass through. The nozzle plate 52 is formed with multiple nozzles N constituting a first row L1 and multiple nozzles N constituting a second row L2. More specifically, the multiple nozzles N of the first row L1 are formed along the Y-axis direction in a region of the nozzle plate 52 on the positive side of the X-axis direction relative to the center plane O, and the multiple nozzles N of the second row L2 are formed along the Y-axis direction in a region on the negative side of the X-axis direction. The nozzle plate 52 is a single plate-like member that is continuous across the portion in which the multiple nozzles N of the first row L1 are formed and the portion in which the multiple nozzles N of the second row L2 are formed. The nozzle plate 52 is manufactured by processing a single-crystal silicon substrate using semiconductor manufacturing techniques, such as dry etching and wet etching. However, known materials and manufacturing methods may be used to manufacture the nozzle plate 52.

[0197] As shown in FIGS. 2 and 3, the first flow path substrate 32 has a space Ra, a plurality of supply channels 61, and a plurality of communication channels 63 formed in each of the first portion P1 and the second portion P2. The space Ra is formed in an elongated shape along the Y-axis direction in a plan view, and the supply channels 61 and the communication channels 63 are through-holes formed for each nozzle N. The communication channels 63 are arranged in the Y-axis direction in a plan view, and the supply channels 61 are arranged in the Y-axis direction between the arrangement of the communication channels 63 and the space Ra. The supply channels 61 are commonly connected to the space Ra. Furthermore, any one communication channel 63 overlaps with the nozzle N corresponding to that communication channel 63 in a plan view. Specifically, any one communication channel 63 in the first portion P1 is connected to one nozzle N in the first row L1 that corresponds to that communication channel 63. Similarly, any one of the communication passages 63 in the second portion P2 communicates with one nozzle N corresponding to that communication passage 63 in the second row L2.

[0198] As shown in FIGS. 2 and 3 , the second flow path substrate 34 is a plate-like member in which multiple pressure chambers C are formed in each of the first portion P1 and the second portion P2. The multiple pressure chambers C are arranged in the Y-axis direction. Each pressure chamber C is formed for each nozzle N and is an elongated space extending along the X-axis direction in a plan view. Like the nozzle plate 52 described above, the first flow path substrate 32 and the second flow path substrate 34 are manufactured by processing a silicon single-crystal substrate using, for example, semiconductor manufacturing technology. However, any known material or manufacturing method may be used to manufacture the first flow path substrate 32 and the second flow path substrate 34. As illustrated above, the flow path forming portion 30 and the nozzle plate 52 include substrates made of silicon. Therefore, for example, as illustrated above, using semiconductor manufacturing technology has the advantage of enabling highly accurate formation of fine flow paths in the flow path forming portion 30 and the nozzle plate 52.

[0199] 2, a vibrating section 42 is provided on the surface of the second flow path substrate 34 opposite to the first flow path substrate 32. The vibrating section 42 is a plate-like member that can vibrate elastically, i.e., a vibrating plate. Note that the second flow path substrate 34 and the vibrating section 42 can also be formed integrally by selectively removing a portion in the plate thickness direction from a region of a plate-like member of a predetermined thickness that corresponds to the pressure chamber C.

[0200] As shown in FIG. 2, the surface Fa of the first flow path substrate 32 and the vibration unit 42 face each other at a distance from each other inside each pressure chamber C. The pressure chamber C is a space located between the surface Fa of the first flow path substrate 32 and the vibration unit 42, and generates a pressure change in the ink composition filled in the space. Each pressure chamber C is, for example, a space with its longitudinal direction in the X-axis direction, and is individually formed for each nozzle N. A plurality of pressure chambers C are arranged in the Y-axis direction in each of the first row L1 and the second row L2. As shown in FIGS. 2 and 3, the end of any one pressure chamber C on the side of the central plane O overlaps with the communicating passage 63 in a plan view, and the end on the opposite side of the central plane O overlaps with the supply passage 61 in a plan view. Therefore, in each of the first portion P1 and the second portion P2, the pressure chamber C communicates with the nozzle N via the communicating passage 63 and with the space Ra via the supply passage 61. It is also possible to add a predetermined flow resistance by forming a throttle flow path in the pressure chamber C, where the flow path width is narrowed.

[0201] As shown in FIG. 2, a plurality of piezoelectric elements 44 corresponding to different nozzles N are provided on the surface of the vibration unit 42 opposite the pressure chambers C, for each of the first portion P1 and the second portion P2. The piezoelectric elements 44 are passive elements that deform when a drive signal is supplied. The plurality of piezoelectric elements 44 are arranged in the Y-axis direction to correspond to each pressure chamber C. As shown in FIG. 4, any one piezoelectric element 44 is a laminate having a piezoelectric layer 443 interposed between a first electrode 441 and a second electrode 442 that face each other. Note that one of the first electrode 441 and the second electrode 442 may be a common electrode that is continuous across the plurality of piezoelectric elements 44. The portion where the first electrode 441, the second electrode 442, and the piezoelectric layer 443 overlap in a planar view functions as the piezoelectric element 44. Note that the portion that deforms when a drive signal is supplied, i.e., the active portion that vibrates the vibration unit 42, may also be defined as the piezoelectric element 44. As described above, the inkjet head 26 includes a first piezoelectric element and a second piezoelectric element. For example, the first piezoelectric element is the piezoelectric element 44 on one side in the X-axis direction as viewed from the central plane O, for example, the right-hand piezoelectric element in FIG. 2, and the second piezoelectric element is the piezoelectric element 44 on the other side in the X-axis direction as viewed from the central plane O, for example, the left-hand piezoelectric element in FIG. 2. When the vibration section 42 vibrates in conjunction with the deformation of the piezoelectric element 44, the pressure in the pressure chamber C fluctuates, causing the ink composition filled in the pressure chamber C to pass through the communicating passage 63 and the nozzle N and be ejected.

[0202] The protective member 46 is a plate-like member for protecting the multiple piezoelectric elements 44, and is placed on the surface of the vibration section 42 or the surface of the second flow path substrate 34. The protective member 46 may be made of any material and manufactured by any method, but like the first flow path substrate 32 and the second flow path substrate 34, the protective member 46 may be formed, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology. The multiple piezoelectric elements 44 are housed in recesses formed in the surface of the protective member 46 on the vibration section 42 side.

[0203] An end of the wiring board 28 is joined to the surface of the vibration section 42 opposite to the flow path forming section 30, or to the surface of the flow path forming section 30. The wiring board 28 is a flexible mounting component on which a plurality of wires (not shown) are formed, which electrically connect the control unit 20 and the inkjet head 26. An end of the wiring board 28 that passes through an opening formed in the protective member 46 and an opening formed in the housing section 48 and extends to the outside is connected to the control unit 20. For example, a flexible wiring board 28 such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable) is preferably used.

[0204] The housing 48 is a case for storing the ink composition to be supplied to the multiple pressure chambers C and the multiple nozzles N. The surface of the housing 48 on the positive side in the Z-axis direction is bonded to the surface Fa of the first flow path substrate 32, for example, with an adhesive. Any known technology or manufacturing method can be used to manufacture the housing 48. For example, the housing 48 can be formed by injection molding.

[0205] As shown in FIG. 2, a space Rb is formed in each of the first portion P1 and the second portion P2 in the casing 48. The space Rb in the casing 48 and the space Ra in the first flow path substrate 32 are interconnected. The space formed by the space Ra and the space Rb functions as a liquid storage chamber R that stores the ink composition to be supplied to the multiple pressure chambers C. The liquid storage chamber R is a common liquid chamber shared by the multiple nozzles N. A liquid storage chamber R is formed in each of the first portion P1 and the second portion P2. The liquid storage chamber R in the first portion P1 is located on the positive side of the X-axis direction relative to the central plane O, and the liquid storage chamber R in the second portion P2 is located on the negative side of the X-axis direction relative to the central plane O. An inlet 482 is formed in the surface of the casing 48 opposite to the first flow path substrate 32, for introducing the ink composition supplied from the ink composition circulation tank 12 into the liquid storage chamber R. Although not shown, a heater for heating the ink composition may be provided on the wall surface defining the space Rb.

[0206] 2, vibration absorbers 54 are provided for each of the first portion P1 and the second portion P2 on the surface Fb of the first flow path substrate 32. The vibration absorbers 54 are flexible films, i.e., compliant substrates, that absorb pressure fluctuations of the ink composition in the liquid storage chamber R. As shown in FIG. 3, the vibration absorbers 54 are provided on the surface Fb of the first flow path substrate 32 so as to close the space Ra of the first flow path substrate 32 and the plurality of supply channels 61, and form the wall surfaces of the liquid storage chamber R, more specifically, the bottom surface.

[0207] 2, a circulation fluid chamber 65 is formed on a surface Fb of the first flow path substrate 32 facing the nozzle plate 52. The circulation fluid chamber 65 is an elongated hole with a bottom that extends in the Y-axis direction in a plan view. The opening of the circulation fluid chamber 65 is closed by the nozzle plate 52 joined to the surface Fb of the first flow path substrate 32.

[0208] As shown in FIG. 5 , the circulation liquid chamber 65 is continuous across the plurality of nozzles N along the first row L1 and the second row L2. Specifically, the circulation liquid chamber 65 is formed between the arrangement of the plurality of nozzles N in the first row L1 and the arrangement of the plurality of nozzles N in the second row L2. Therefore, as shown in FIG. 2 , the circulation liquid chamber 65 is located between the communication passage 63 in the first portion P1 and the communication passage 63 in the second portion P2. As described above, the flow path forming section 30 is a structure in which the first pressure chamber (pressure chamber C) in the first portion P1 and the first communication passage (communication passage 63) are formed, the second pressure chamber (pressure chamber C) in the second portion P2 and the second communication passage (communication passage 63) are formed, and the circulation liquid chamber 65 is located between the communication passage 63 in the first portion P1 and the communication passage 63 in the second portion P2. As shown in FIG. 2 , the flow path forming section 30 includes a partition wall portion 69, which is a wall-like portion that separates the circulation liquid chamber 65 from each of the communication passages 63.

[0209] As described above, the multiple pressure chambers C and the multiple piezoelectric elements 44 are arranged in the Y-axis direction in each of the first portion P1 and the second portion P2. Therefore, in other words, the circulating liquid chamber 65 extends in the Y-axis direction so as to be continuous across the multiple pressure chambers C or the multiple piezoelectric elements 44 in each of the first portion P1 and the second portion P2. Alternatively, the circulating liquid chamber 65 and the liquid storage chamber R extend in the Y-axis direction with a gap between them, and the pressure chambers C, the communication passages 63, and the nozzles N are located within that gap.

[0210] As shown in FIG. 6, each nozzle N includes a first section n1 and a second section n2. The first section n1 and the second section n2 are circular spaces that are coaxially formed and communicate with each other. The second section n2 is located on the flow path forming section 30 side as viewed from the first section n1. The inner diameter d2 of the second section n2 is larger than the inner diameter d1 of the first section n1. The stepped configuration of each nozzle N as described above has the advantage of making it easier to set the flow path resistance of each nozzle N to the desired characteristics. Furthermore, as shown in FIG. 6, the central axis Qa of each nozzle N is located on the opposite side of the circulating fluid chamber 65 as viewed from the central axis Qb of the communicating passage 63.

[0211] 6, a plurality of circulation paths 72 are formed in each of the first portion P1 and the second portion P2 on the surface of the nozzle plate 52 facing the flow path forming portion 30. The plurality of circulation paths 72 in the first portion P1 correspond one-to-one to the plurality of nozzles N in the first row L1. Furthermore, the plurality of circulation paths 72 in the second portion P2 correspond one-to-one to the plurality of nozzles N in the second row L2.

[0212] Each circulation path 72 is a groove extending in the X-axis direction, i.e., a long, bottomed hole, and functions as a flow path for circulating the ink composition. The circulation path 72 is formed at a position spaced apart from the nozzle N, specifically, on the circulation liquid chamber 65 side as viewed from the nozzle N corresponding to the circulation path 72. For example, the multiple nozzles N, particularly the second section n2, and the multiple circulation paths 72 are formed collectively in a common process using semiconductor manufacturing technology, which is a processing technology such as dry etching or wet etching.

[0213] As shown in FIG. 6 , each circulation path 72 is formed linearly with a flow path width Wa equal to the inner diameter d2 of the second section n2 of the nozzle N. Furthermore, the flow path width Wa of the circulation path 72, i.e., the dimension of the circulation path 72 in the Y-axis direction, is smaller than the flow path width Wb of the pressure chamber C, i.e., the dimension of the pressure chamber C in the Y-axis direction. Therefore, the flow path resistance of the circulation path 72 can be increased compared to a configuration in which the flow path width Wa of the circulation path 72 is larger than the flow path width Wb of the pressure chamber C. Meanwhile, the depth of the circulation path 72 relative to the surface of the nozzle plate 52 is constant throughout its entire length. Specifically, each circulation path 72 is formed to a depth equal to the second section n2 of the nozzle N. This configuration has the advantage of making it easier to form the circulation path 72 and the second section n2 compared to a configuration in which the circulation path 72 and the second section n2 are formed to different depths. The “depth” of the flow path refers to the depth of the flow path in the Z-axis direction.

[0214] Any one of the circulation paths 72 in the first portion P1 is located on the circulation liquid chamber 65 side when viewed from the nozzle N in the first row L1 that corresponds to that circulation path 72. Any one of the circulation paths 72 in the second portion P2 is located on the circulation liquid chamber 65 side when viewed from the nozzle N in the second row L2 that corresponds to that circulation path 72. The end of each of the circulation paths 72 on the opposite side from the center plane O, i.e., on the communicating path 63 side, overlaps with the corresponding communicating path 63 in plan view. That is, the circulation path 72 communicates with the communicating path 63. On the other hand, the end of each of the circulation paths 72 on the center plane O side, i.e., on the circulating liquid chamber 65 side, overlaps with the circulating liquid chamber 65 in plan view. That is, the circulation path 72 communicates with the circulating liquid chamber 65. In this way, each of the multiple communicating paths 63 communicates with the circulating liquid chamber 65 via the circulation path 72. 6, the ink composition in each communication passage 63 is supplied to the circulation liquid chamber 65 via the circulation path 72. That is, the plurality of communication passages 63 corresponding to the first row L1 and the plurality of communication passages 63 corresponding to the second row L2 are in communication with one circulation liquid chamber 65 in common.

[0215] FIG. 6 illustrates the flow path length La of a portion of any one circulation path 72 that overlaps with the circulation liquid chamber 65, the flow path length Lb of a portion of the circulation path 72 that overlaps with the communicating path 63, and the flow path length Lc of a portion of the circulation path 72 that overlaps with the partition wall 69 of the flow path forming section 30. The flow path length Lc corresponds to the thickness of the partition wall 69. The partition wall 69 functions as a throttle portion of the circulation path 72. Therefore, the longer the flow path length Lc, which corresponds to the thickness of the partition wall 69, the greater the flow path resistance of the circulation path 72. In this embodiment, the relationship holds that the flow path length La is longer than the flow path length Lb, and the flow path length La is longer than the flow path length Lc. Furthermore, in this embodiment, the relationship holds that the flow path length Lb is longer than the flow path length Lc. The above configuration has the advantage that the ink composition more easily flows from the communicating path 63 to the circulation liquid chamber 65 via the circulation path 72, compared to a configuration in which the flow path length La and the flow path length Lb are shorter than the flow path length Lc.

[0216] As described above, in this embodiment, the pressure chamber C is indirectly connected to the circulation liquid chamber 65 via the communicating passage 63 and the circulation path 72. In other words, the pressure chamber C and the circulation liquid chamber 65 are not directly connected to each other. In the above configuration, when the pressure inside the pressure chamber C fluctuates due to the operation of the piezoelectric element 44, a portion of the ink composition flowing inside the communicating passage 63 is ejected to the outside from the nozzle N, and the remaining portion flows from the communicating passage 63 into the circulation liquid chamber 65 via the circulation path 72. In this embodiment, the inertances of the communicating passage 63, the nozzle N, and the circulation path 72 are selected so that the amount of ink composition flowing through the communicating passage 63 in a single actuation of the piezoelectric element 44 and ejected through the nozzle N (hereinafter referred to as the "ejection amount") exceeds the amount of ink composition flowing through the communicating passage 63 and flowing into the circulation liquid chamber 65 via the circulation path 72 (hereinafter referred to as the "circulation amount"). Hereinafter, of the ink composition flowing through the communicating passage 63 by one actuation of the piezoelectric element 44, the amount of ink composition ejected through the nozzle N will be referred to as the "ejection amount," and the amount of ink composition flowing through the communicating passage 63 and flowing into the circulating liquid chamber 65 via the circulation path 72 will be referred to as the "circulation amount." In other words, assuming that all of the piezoelectric elements 44 are driven simultaneously, the total circulation amount flowing into the circulating liquid chamber 65 from the multiple communicating passages 63 is greater than the total ejection amount from the multiple nozzles N.

[0217] Specifically, the respective flow path resistances of the communicating path 63, the ink composition, and the circulation path 72 are determined so that the ratio of the circulated amount of ink composition flowing through the communicating path 63 is 70% or more. With the above configuration, it is possible to effectively circulate the ink composition near the nozzle N to the circulation liquid chamber 65 while ensuring the ejection amount of the ink composition. Generally speaking, there is a tendency that the greater the flow path resistance of the circulation path 72, the smaller the circulation amount and the smaller the ejection amount.

[0218] The recording device 100 includes a circulation mechanism 75 . The circulation mechanism 75 is a mechanism for circulating the ink composition inside the circulation liquid chamber 65 .

[0219] The circulation mechanism 75 sends the ink composition in the circulation liquid chamber 65 to the ink composition circulation tank 12, and the ink composition contained in the ink composition circulation tank 12 is mixed with the ink composition supplied from the ink composition storage container 11.

[0220] The circulation mechanism 75 may include, for example, a suction mechanism such as a pump that sucks the ink composition from the circulation liquid chamber 65, a filter mechanism that collects air bubbles and foreign matter mixed in the ink composition, and a heating mechanism that reduces thickening of the ink composition by heating it. The ink composition is supplied from the circulation mechanism 75 to the liquid storage chamber R via the inlet 482. In this manner, in this embodiment, the ink composition circulates through the route of the liquid storage chamber R → supply channel 61 → pressure chamber C → communicating passage 63 → circulation channel 72 → circulation liquid chamber 65 → circulation mechanism 75 → ink composition circulation tank 12 → inlet 482 → liquid storage chamber R.

[0221] Among these paths, the circulation return path corresponds to the communication passage 63 → circulation path 72 → circulating liquid chamber 65 → circulation mechanism 75 → ink composition circulation tank 12. In circulation, the flow of the ink composition through the circulation return path is specifically referred to as return.

[0222] In each of the above figures, the ink composition supplied into the inkjet head 26 passes through the circulation return path without being ejected from the nozzles N, is discharged to the outside of the inkjet head 26, and is returned to the ink composition circulation tank 12. In other words, this is a circulation return path that returns the ink composition from the inkjet head 26. The ink composition that has returned to the ink composition circulation tank 12 is supplied again to the inkjet head 26. In this case, it is possible to circulate the ink composition inside and outside the inkjet head 26, which is preferable because it is possible to more effectively suppress the generation of foreign matter in the ink composition.

[0223] It should be noted that when the recording apparatus 100 is said to have a circulation path for circulating the ink composition, the circulation path is a circulation path in a broad sense, meaning the entire portion for circulating the ink composition that is provided between the ink composition circulation tank 12 and the inkjet head 26 or within the inkjet head 26. The circulation path 72 in Figure 5 etc. is a circulation path in a narrow sense, being a part of the circulation path in the broad sense.

[0224] Furthermore, the ink composition circulation tank 12 does not have to be tank-shaped, and it is sufficient if there is a confluence point where the ink composition returning through the circulation return path and the ink composition discharged from the ink composition storage container 11 can merge.

[0225] In this embodiment, as shown in FIG. 5 , the circulation mechanism 75 draws the ink composition from both sides of the circulation liquid chamber 65 in the Y axis direction. That is, the circulation mechanism 75 draws the ink composition from the vicinity of the negative end of the circulation liquid chamber 65 in the Y axis direction and the vicinity of the positive end of the circulation liquid chamber 65 in the Y axis direction. Note that if the ink composition is drawn from only one end of the circulation liquid chamber 65 in the Y axis direction, a difference in the pressure of the ink composition will occur between both ends of the circulation liquid chamber 65. Due to the pressure difference within the circulation liquid chamber 65, the pressure of the ink composition in the communicating passage 63 may differ depending on the position in the Y axis direction. Therefore, the ejection characteristics, such as the ejection volume and ejection speed, of the ink composition from each nozzle N may differ depending on the position in the Y axis direction. In contrast, in this embodiment, the ink composition is drawn from both sides of the circulation liquid chamber 65, reducing the pressure difference within the circulation liquid chamber 65. Therefore, the ejection characteristics of the ink composition can be approximated with high accuracy across multiple nozzles N arranged in the Y axis direction. However, if the pressure difference in the Y-axis direction within the circulating liquid chamber 65 does not pose a particular problem, a configuration in which the ink composition is sucked from one end of the circulating liquid chamber 65 can also be employed.

[0226] As described above, the circulation path 72 and the communicating path 63 overlap in a planar view, and the communicating path 63 and the pressure chamber C overlap in a planar view. Therefore, the circulation path 72 and the pressure chamber C overlap in a planar view. On the other hand, as shown in FIGS. 5 and 6, the circulation fluid chamber 65 and the pressure chamber C do not overlap in a planar view. Also, as shown in FIG. 2, the piezoelectric element 44 is formed throughout the pressure chamber C along the X-axis direction, so the circulation path 72 and the piezoelectric element 44 overlap in a planar view, but the circulation fluid chamber 65 and the piezoelectric element 44 do not overlap in a planar view. In other words, the pressure chamber C or the piezoelectric element 44 overlaps with the circulation path 72 in a planar view, but does not overlap with the circulation fluid chamber 65 in a planar view. Therefore, compared to a configuration in which the pressure chamber C or the piezoelectric element 44 does not overlap with the circulation path 72 in a planar view, for example, this configuration has the advantage of making it easier to miniaturize the inkjet head 26.

[0227] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

[0228] For example, the recording apparatus to which the present invention is applied is not limited to the above-mentioned one. More specifically, for example, in the above-described embodiment, the description has been centered on a configuration having a circulation mechanism for circulating the ink composition, but the recording apparatus to which the present invention is applied does not have to have a circulation mechanism. If the recording apparatus does not have a circulation mechanism, this is preferable because the recording apparatus can be simplified.

[0229] Furthermore, in the above-described embodiment, the recording apparatus has been mainly described as having a serial type inkjet head as the inkjet head, but the inkjet may be a line type inkjet head.

[0230] Furthermore, the recording method of the present invention may further include other steps in addition to the steps described above.

[0231] Although the above-described embodiment has been mainly described with reference to a case where each step is performed using the same apparatus, some steps of the recording method of the present invention may be performed using different apparatuses. More specifically, the apparatus that performs the primary heating step may be a different apparatus from the inkjet-equipped apparatus that performs the deposition step. [Example]

[0232] Next, specific examples of the present invention will be described. [3] Preparation of ink composition (Preparation Examples 1 to 28) Ink compositions were obtained by mixing the components to obtain the formulations shown in Tables 1 and 2. The pigment, which is the coloring material, was previously prepared by mixing the pigment:dispersant in a mass ratio of 1:0.5 with water using a dispersant that is a styrene acrylic resin not listed in the tables, and stirring thoroughly in a bead mill to prepare a pigment dispersion, which was then used to prepare the ink.

[0233] The compositions of the ink compositions of Preparation Examples 1 to 28 are summarized in Tables 1 and 2. In Tables 1 and 2, the coloring materials CI Pigment Blue 15:3 is referred to as "PB15:3," styrene acrylic resin (solid content of JONCRYL 631 manufactured by BASF) is referred to as "J631," and polyolefin wax (AQUACER manufactured by BYK) is referred to as "J631." "WAX1" is a specific organic compound (solid content: 515%), "NPG" is neopentyl glycol as a specific organic compound, "PIN" is pinacol as a specific organic compound, "1,2-CHD" is 1,2-cyclohexanediol as a specific organic compound, "CL" is ε-caprolactam as a specific organic compound, "PG" is propylene glycol as an organic solvent, "1,3-butanediol" as an organic solvent, "SAG002" is Silface SAG002 (manufactured by Nissin Chemical Industry Co., Ltd.), a silicone surfactant with an HLB value of 12, i.e., a specific surfactant, "SAG005" is Silface SAG005 (manufactured by Nissin Chemical Industry Co., Ltd.), a silicone surfactant with an HLB value of 7, i.e., a specific surfactant, "SAG021" is Silface SAG021 (manufactured by Nissin Chemical Industry Co., Ltd.), a silicone surfactant with an HLB value of 3, i.e., a specific surfactant, "SAG021" is Disponil SUS IC as a sulfonic acid type anionic surfactant. The ink composition of each of the above preparation examples was measured using a vibration viscometer in accordance with JIS Z8809 and had a viscosity of 3 mPa·s or more and 8 mPa·s or less at 25°C. The specific organic compounds, organic solvents, and other organic compounds used in the above preparation examples were listed in Table 3, along with the melting points, normal boiling points, and solubility in water at 25°C.

[0234] [Table 1]

[0235] [Table 2]

[0236] [Table 3]

[0237] [4] Production of recorded materials Example 1 First, a recording device was prepared by modifying a Seiko Epson SC-40650 to have the configuration shown in Figures 1 to 6, with a nozzle array nozzle density of 360 dpi and 360 nozzles. A circulation mechanism was attached to the inkjet head. An ink composition container containing the ink composition prepared in Preparation Example 1 was attached to this recording device.

[0238] Next, the ink composition was supplied from the ink composition container to the inkjet head via the ink composition circulation tank.

[0239] The ink composition was then ejected from the inkjet head while circulating through the flow path of the circulation mechanism, and then heated by the primary heating means and secondary heating means, resulting in a recorded product with a solid print pattern. More specifically, while a polyethylene terephthalate film (PET50A, manufactured by Lintec Corporation) serving as the recording medium was conveyed by the conveyance mechanism, the ink composition was ejected onto the recording medium in a solid print pattern. Immediately thereafter, the platen heater, serving as the primary heating means, was controlled to heat the recording medium to a surface temperature of 35°C, and then the curing heater, serving as the secondary heating means downstream of this, heated the recording medium to a surface temperature of 80°C, resulting in a recorded product. The recorded product was produced by a four-pass recording method in which the distance of one sub-scan was one-fourth the length of the nozzle row, and ink was deposited in the same area with four main scans. The amount of ink composition deposited at each location on the recording medium was 10 mg / inch. 2 It was decided.

[0240] Examples 2 to 8 Recorded matter was produced in the same manner as in Example 1, except that the types of ink compositions were changed as shown in Table 4.

[0241] Example 9 A recording device not equipped with a circulation mechanism was used, and recorded matter was produced in the same manner as in Example 1, except that the ink was not circulated.

[0242] (Examples 10 to 30) Recorded matter was produced in the same manner as in Example 9, except that the type of ink composition and the heating temperature by the primary heating means were as shown in Tables 4 and 5.

[0243] (Comparative Examples 1 to 18) Recorded matter was produced in the same manner as in Example 9, except that the type of ink composition, the presence or absence of heat treatment by primary heating means, and the heating temperature were as shown in Table 5. In the examples without the primary heating step, the platen heater was stopped and no primary heating was performed.

[0244] The production conditions for the recorded matter in each of the above examples are summarized in Tables 4 and 5. In Tables 4 and 5, in the column for type of ink composition, the ink composition prepared in Preparation Example 1 is shown as Ink 1, and similarly, the ink compositions prepared in Preparation Examples 2 to 28 are shown as Inks 2 to 28, respectively.

[0245] [Table 4]

[0246] [Table 5]

[0247] [5] Evaluation [5-1] Discharge stability Recorded materials were produced in the same manner as described in [4] above, except that intermittent ejection was performed by alternating between idle running, which prevents the ink composition from being ejected from the head during printing, and main scanning, which ejects ink. After one hour of continuous operation, the condition of the inkjet nozzle was checked and evaluated according to the following criteria: C or above was considered to be good.

[0248] A: There are no non-ejecting nozzles. B: The percentage of non-ejecting nozzles is 2% or less. C: The percentage of non-ejecting nozzles is more than 2% and 5% or less. D: The percentage of non-ejecting nozzles exceeds 5%.

[0249] [5-2] Aggregation unevenness (4-pass printing) The recorded portion of the four-pass recording of each of the recorded materials produced in each of the Examples and Comparative Examples was visually observed and evaluated according to the following criteria: C or higher was considered to be a good level.

[0250] A: No aggregation irregularities are observed, and the image is homogeneous. B: There is a slight amount of fine unevenness in aggregation. C: There are some large irregularities in aggregation. D: There is a large amount of uneven aggregation.

[0251] [5-3] Unevenness due to coffee stain phenomenon The four-pass printed portion of each of the recorded materials produced in each of the Examples and Comparative Examples was visually observed and evaluated according to the following criteria.

[0252] Separately, printing was performed in the same manner, except that the distance of one sub-scan was set to one-eighth of the length of the nozzle row, and eight main scans were performed to deposit ink in the same area, resulting in eight passes. The printing area of ​​the printing medium was evaluated in the same manner.

[0253] A: No unevenness due to the coffee stain phenomenon is observed, and the image is homogeneous. B: There is slight unevenness due to the coffee stain phenomenon. C: Unevenness due to coffee stain phenomenon is clearly observed.

[0254] [5-4] Image gloss Each of the recorded materials produced in the above-mentioned Examples and Comparative Examples was visually observed and evaluated according to the following criteria.

[0255] A: It has a glossy finish. B: No gloss.

[0256] [5-5]Abrasion resistance The recorded portion of each of the recorded materials produced in each of the Examples and Comparative Examples was rubbed 50 times with a moistened Kanakin with a load of 500 g, and the condition was then visually observed and evaluated according to the following criteria: C or higher was considered to be a good level.

[0257] A: No change was observed at all. B: Peeling of the recorded area is observed, but the recording medium is not exposed. C: Peeling of the recorded area was observed, and the recording medium was slightly exposed. D: Peeling of the recorded area was observed, and the recording medium was clearly exposed.

[0258] [5-6]Secondary drying property Recorded matter was produced in the same manner as described in [4] above, except that heating with a curing heater, which is a secondary heating means, was not performed, and the recorded matter was subjected to heat treatment in an oven while changing the heating temperature at various times. The heating temperature required to dry the surface of the recorded area to the point where it was no longer sticky to the touch was confirmed, and evaluated according to the following criteria. The lower this temperature, the better the secondary drying properties.

[0259] A: The oven temperature at which it becomes non-sticky is 70°C or below. B: The oven temperature at which the product becomes non-sticky is above 70°C and below 75°C. C: The oven heating temperature at which the product becomes non-sticky is over 75°C.

[0260] [5-7] Aggregation unevenness (8-pass printing) Printing was carried out in the same manner as in [5-2] above, except that the distance of one sub-scan was set to one-eighth of the length of the nozzle row, and eight main scans were performed to deposit ink in the same area, resulting in an 8-pass printing, and the printed area of ​​the printing medium was evaluated in the same manner as for aggregation unevenness above. Note that a higher number of passes tends to reduce aggregation unevenness, so aggregation unevenness tends to be evaluated better overall compared to 4-pass printing.

[0261] These results are summarized in Tables 6 and 7.

[0262] [Table 6]

[0263] [Table 7]

[0264] As shown in Tables 6 and 7, in all of the examples in which the ink contained a specific organic compound and the primary heating process was performed, the ejection stability, reduction in aggregation unevenness, and abrasion resistance were all excellent.

[0265] In contrast, the comparative examples in which this was not the case were inferior in any one of ejection stability, reduction of aggregation unevenness, and abrasion resistance.

[0266] From Examples 9 to 27, excellent ejection stability was obtained even when a recording apparatus not equipped with a circulation mechanism was used.

[0267] A comparison between Examples 9 and 24 shows that ink containing an organic solvent had better ejection stability.

[0268] From Comparative Examples 1, 2, 15, etc., when the ink did not contain the specific organic compound, the ejection stability, reduction in aggregation unevenness, or abrasion resistance was poor.

[0269] As can be seen from Comparative Example 9 and the like, when the primary heating step was not provided, the reduction of aggregation unevenness was poor. [Explanation of symbols]

[0270] 100...recording device, 11...ink composition storage container, 12...ink composition circulation tank, 13...IR heater, 14...platen heater, 15...curing heater, 16...cooling fan, 17...preheater, 18...ventilation fan, 20...control unit, 21...casing, 22...carriage movement mechanism, 23...transport means, 26...inkjet head, 28...wiring board, 30...flow path forming section, 32...first flow path substrate, 34...second flow path substrate, 42...vibration section, 44...piezoelectric element, 441...first electrode, 441...second electrode, 443...piezoelectric layer, 46...protective member, 48...casing section, 482...inlet port, 52...Nozzle plate, 54...Vibration absorber, 61...Supply path, 63...Communicating path, 65...Circulating liquid chamber, 69...Partition wall portion, 72...Circulation path, 75...Circulation mechanism, 9...Carriage, C...Pressure chamber, d1...Inner diameter, d2...Inner diameter, Fa...Surface, Fb...Surface, L1...First row, L2...Second row, La...Flow path length, Lb...Flow path length, Lc...Flow path length, M...Recording medium, MS...Main scanning direction, N...Nozzle, n1...First section, n2...Second section, O...Center plane, P1...First portion, P2...Second portion, R...Liquid storage chamber, Ra...Space, Rb...Space, SS...Sub-scanning direction, Qa...Center axis, Qb...Center axis, Wa...Flow path width, Wb...Flow path width

Claims

1. an application step of ejecting the ink composition from an inkjet head and applying it to a recording medium; 、 a primary heating step of heating the ink composition adhered to the recording medium in the adhesion step; and, the recording medium is a low-absorbency recording medium or a non-absorbency recording medium; The primary heating step is a step of heating the ink composition to adhere to the heated recording medium, or The ink composition droplets are heated within 0.5 seconds after they are deposited on the recording medium. can be, the surface temperature of the recording medium when the ink composition is heated in the primary heating step is , 28 to 48°C; The ink composition has a normal boiling point of 280°C or less, is solid at 25°C, and and water containing an organic compound having a solubility in water at 25°C of 50 [g / 100g of water] or more. It is an ink of the same type, the content of the organic compound in the ink composition is 15.0% by mass or less, The ink composition has a normal boiling point of 160 to 230°C and is liquid at 25°C. A recording method containing polyols as an organic solvent.

2. 2. The recording medium according to claim 1, wherein the normal boiling point of the organic compound is 160° C. or higher and 280° C. or lower. method.

3. the content of the organic compound in the ink composition is 2.0% by mass or more and 15.0% by mass or less 3. The recording method according to claim 1, wherein

4. 4. The organic compound according to claim 1, wherein the melting point of the organic compound is higher than 25°C and not higher than 150°C. Item 2. The recording method described in item 1.

5. The organic compound may be a diol having an aliphatic skeleton with a branched structure, a diol having a cyclic structure, or and at least one selected from the group consisting of diols and cyclic amides. Item 5. The recording method according to any one of items 1 to 4.

6. The organic compound is neopentyl glycol, 1,2-cyclohexanediol, pina Coal, ε-caprolactam, 2-ethyl-2-methyl-1,3-propanediol, 2 -methyl-2-propyl-1,3-propanediol, 2,5-dimethyl-2,5-hexyl 6. The recording method according to claim 5, wherein the solvent is at least one selected from the group consisting of sandiol and sandiol.

7. The ink composition has a normal boiling point of 170 to 230°C and is liquid at 25°C.

7. The recording medium according to claim 1, wherein the recording medium contains a polyol as an organic solvent. method.

8. The ink composition contains a silicone surfactant having an HLB value of 10 or less. Item 8. The recording method according to any one of items 1 to 7.

9. the surface temperature of the recording medium when the ink composition is heated in the primary heating step is The recording method according to claim 1 , wherein the temperature is 30° C. or higher and 48° C. or lower.

10. The number of main scans for the same scanning area of ​​the recording medium is 1 to 10.

10. The recording method according to any one of claims 1 to 9.

11. The inkjet head is provided with a circulation mechanism for circulating the ink composition.

11. The recording method according to claim 1, wherein

12. a second heating step for further heating the recording medium after the first heating step; 12. The recording method according to any one of items 1 to 11.

13. The low-absorbency recording medium is a coated paper, and the non-absorbency recording medium is a paper on which an ink-absorbing layer is formed.

13. The film according to claim 1, wherein the film is an uncoated plastic film. Recording method.

14. A recording apparatus for performing recording by the recording method according to any one of claims 1 to 13. hand, the ink composition; a primary heating means for heating the recording medium in the primary heating step; an inkjet head that ejects the ink composition onto the recording medium, A recording device.

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