Printing apparatus and printing method

Abstract

This invention relates to a printing apparatus and a printing method. The ink, which is the object of printing, comprises a medium, a colorant, a fixing polymer, and one or more polymers other than the fixing polymer. The colorant is soluble in or dispersed in the medium. The fixing polymer has a glass transition temperature (Tg) higher than room temperature and is dispersed in the medium. One or more polymers other than the fixing polymer have a Tg higher than room temperature and are soluble in or dispersed in the medium. The Tg of the fixing polymer is higher than the Tg of at least 80% by mass of all polymers in the ink other than the fixing polymer that have a Tg higher than room temperature.

Description

[0001] This application is a divisional application of the invention patent application filed on August 25, 2021, with application number 202180053628.6 and entitled "Ink, Ink Composition and Printing Apparatus". Technical Field

[0002] This invention relates to ink, ink set, printing apparatus, and printing method. Background Technology

[0003] As inks, there are known inks that contain polymers in addition to a medium (e.g., a solvent) and a colorant (e.g., Patent Document 1 below). Patent Document 1 discloses an ink containing a pigment dispersion polymer for dispersing pigments and a fixing aid polymer for improving the scrub resistance of printed matter.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2017 / 138436 Summary of the Invention

[0007] An ink according to one aspect of the present invention comprises a medium, a colorant, a fixer polymer, and one or more polymers other than the fixer polymer. The colorant is soluble in or dispersed in the medium. The fixer polymer has a glass transition temperature above room temperature and is dispersed in the medium. The one or more polymers have a glass transition temperature above room temperature and are soluble in or dispersed in the medium. The glass transition temperature of the fixer polymer is higher than the glass transition temperature of at least 80% by mass of all polymers in the ink other than the fixer polymer that have a glass transition temperature above room temperature.

[0008] One aspect of the ink composition of the present invention comprises two inks, each of which is one of the inks described above, and the colorants in the two inks are different from each other. At least one of the two inks contains an ultraviolet absorber other than the colorant. The content of the ultraviolet absorber in the two inks is different from each other.

[0009] One aspect of the printing apparatus of the present invention includes an ink ejection device, a drying device, and a melting device. The ink ejection device causes the ink to adhere to a workpiece. The drying device promotes the evaporation of the medium by heating the workpiece. The melting device melts the fixer polymer by heating the ink adhered to the workpiece, thereby fixing the ink to the workpiece. Attached Figure Description

[0010] Figure 1 This is a side view of the printing apparatus according to the first embodiment.

[0011] Figure 2 yes Figure 1 A top view of the printing apparatus.

[0012] Figure 3A Viewed from above Figure 1 The stereoscopic image is obtained from the inkjet head of the printing device.

[0013] Figure 3B Viewed from below Figure 3A The stereoscopic image is obtained from the inkjet head.

[0014] Figure 3C Viewed from above Figure 3A A three-dimensional image obtained from a part of the inkjet head (head body).

[0015] Figure 3D yes Figure 3C A magnified view of region IIId.

[0016] Figure 4 It is shown Figure 1 A block diagram of the signal processing system structure of the printing apparatus.

[0017] Figure 5 This means that in Figure 1 A conceptual diagram of a method for fixing ink in a printing apparatus.

[0018] Figure 6 This is a graph showing the estimated time required for the medium to evaporate from the ink.

[0019] Figure 7 It is shown Figure 1 A graph showing the estimated temperature distribution of the printed material in the printing apparatus.

[0020] Figure 8A This is a graph illustrating the estimated temperature change of the resin when heated by UV light.

[0021] Figure 8B This indicates that it includes Figure 8A A graph showing the estimated results of the water temperature change in the resin.

[0022] Figure 9 This is a side view of the printing apparatus according to the second embodiment.

[0023] Figure 10 This is a side view of the printing apparatus according to the third embodiment.

[0024] Figure 11This is a side view of the printing apparatus according to the fourth embodiment.

[0025] Figure 12A This is a schematic diagram illustrating an example of the light absorption characteristics of inks of different colors.

[0026] Figure 12B This is a schematic diagram illustrating the ink composition of the modified example.

[0027] Figure 13A This is a schematic diagram illustrating an example of the light absorption characteristics of a UV absorber.

[0028] Figure 13B This is a schematic diagram illustrating an example of the light absorption characteristics of a modified ink.

[0029] Figure 14 This is a diagram illustrating a method for manufacturing the polymer contained in the ink of an embodiment.

[0030] Figure 15 This is a diagram illustrating a method for manufacturing the dispersion system contained in the ink of an embodiment.

[0031] Figure 16 This is a diagram illustrating the method of manufacturing ink in an embodiment.

[0032] Explanation of reference numerals in the attached figures

[0033] 1…printing apparatus, 7…ink ejection apparatus, 9…drying apparatus, 11…melting apparatus, 101…printed material, 103…ink, 105…medium, 109…fixer polymer. Detailed Implementation

[0034] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the following drawings are schematic. Therefore, details are sometimes omitted. Furthermore, the size ratios may not necessarily match actual size ratios. The size ratios of multiple drawings may also not necessarily match each other. Sometimes, specific dimensions are shown as larger than actual dimensions, or specific shapes are exaggerated.

[0035] In the descriptions following the second embodiment, the parts that differ from the previously described embodiments will be described in detail. Matters not specifically mentioned may be the same as those in the previously described embodiments, or may be inferred by analogy from the previously described embodiments. Furthermore, in the various embodiments, corresponding structures may sometimes be labeled with the same reference numerals, even if the details differ.

[0036] The term "medium" can refer to either a solvent (or a medium) that dissolves other substances (solutes) or a dispersion medium that disperses other substances (dispersed phases). The term "dispersion medium" is generally used in a narrow sense to refer to a medium in which particles (dispersed phases) of a certain size (e.g., a particle size of 1 nm or larger) are dispersed, and also in a broad sense to include solvents in addition to the narrow definition of dispersion medium. In this invention, it is used in the narrow sense.

[0037] As is known, the term "particle" as a dispersed phase is not limited to solids, but can also be liquids or gases. However, in this invention, when referred to simply as "particle," unless otherwise specified, it refers to particles of a solid rather than particles as a dispersed phase.

[0038] The term "glass" is generally used, for example, in a narrow sense to refer to a substance primarily composed of silicates, and in a broad sense to refer to a substance that, upon heating, becomes an amorphous solid exhibiting a glass transition. In this invention, it is used in the broad sense. Therefore, when referred to as glass or glass composition in this invention, these terms are not limited to substances primarily composed of silicates; for example, substances primarily composed of polymers may also be used.

[0039] The "glass transition temperature" (glass transition point) is, as is generally known, the temperature at which a glass transition occurs. Hereinafter, the glass transition temperature is sometimes simply referred to as "Tg". Tq can be measured according to standards such as JIS (Japanese Industrial Standard) K7121. When more stringent requirements are needed, Tg can be set as the midpoint of the extrapolated glass transition onset temperature, midpoint glass transition temperature, and extrapolated glass transition termination temperature defined in the aforementioned standards. Alternatively, the extrapolated glass transition onset temperature can be used when maintaining a state below Tg, and the extrapolated glass transition termination temperature can be used when maintaining a state above Tg.

[0040] "Color difference" can also be calculated using the formula specified in "7.1.1 Color difference of L*a*b* table color system" of JIS Z8730 (currently obsolete).

[0041] "Room temperature" can be set, for example, as specified in JIS Z8703, at 20±15°C. In cases where stricter requirements are needed, room temperature can be set, for example, at 20°C.

[0042] <First Implementation Method>

[0043] (Overall structure of the printing apparatus)

[0044] Figure 1 This is a side view of the printing apparatus 1 according to the first embodiment of the present invention. Figure 2 This is a top view of printing apparatus 1.

[0045] For convenience, these diagrams are labeled with a fixed orthogonal coordinate system D1-D2-D3 in space. The printing apparatus 1 can be set to any vertical direction, but for convenience, the +D3 side is set to the vertically upward direction. Unless otherwise specified, the terms "view from above" or "view through from above" refer to observation along the D3 axis.

[0046] The printing apparatus 1, for example, conveys the printed material 101 from the supply roller 3A to the return roller 3B. The supply roller 3A, the return roller 3B, and various rollers described later constitute the conveying device 5 for conveying the printed material 101. The printing apparatus 1 has various devices along the conveying path of the printed material 101. For example, the printing apparatus 1 has an ink ejection device 7 that sprays ink droplets toward the printed material 101, and multiple devices (e.g., 9, 11, and 13) that facilitate the fixing of the ink ejected by the ink ejection device 7 onto the printed material 101. In addition, the printing apparatus 1 has a control device 15 that controls the various devices described above. Figure 1 ).

[0047] The printing apparatus 1 may also have a structure other than those described above. For example, the printing apparatus 1 may also have a coating machine (not shown) between the supply roller 3A and the ink ejection device 7, which uniformly coats the workpiece 101 with a coating agent (described later). In addition, for example, the printing apparatus 1 may also have a cleaning section for cleaning the head 21 (described later) of the ink ejection device 7.

[0048] (Printed material)

[0049] The printed object 101 is, for example, in the form of a strip or sheet. Before printing, the printed object 101 is wound around the supply roller 3A. The printed object 101 is fed from the supply roller 3A, passes under the ink ejection device 7, and is wound around the recovery roller 3B for recycling. The material, width, length, and thickness of the printed object 101 can be appropriately set. For example, the material of the printed object 101 can be paper, resin, or cloth. The thickness of the resin (e.g., PET: polyethylene terephthalate) film of the printed object 101 can be appropriately set. As an example of a range for this thickness, it is 5 μm or more and 20 μm or less. In the following description, the side of the printed object 101 with ink adhering to it is sometimes referred to as the surface (front side), and the opposite side is referred to as the back side.

[0050] (Ink)

[0051] The ink ejected from the ink ejection device 7 contains, for example, a medium (solvent and / or dispersion medium), a colorant, and several types of polymers. These polymers include at least a fixing polymer. After the ink is ejected and drips onto the substrate 101, the medium within the ink evaporates. Additionally, the fixing polymer is heated and melted (e.g., becomes glassy), and then solidifies. Through this process, the colorant is fixed to the substrate 101.

[0052] It should be noted that, as understood from the above description, the ink of this embodiment is not, for example, a UV-curable ink. UV-curable inks contain a synthetic resin (i.e., a UV-curable resin) that reacts with the energy of ultraviolet light to chemically change from a liquid to a solid state, and is fixed to the printed material 101 by the curing action of the UV-curable resin. The ink of this embodiment substantially does not contain such a UV-curable resin (polymer). However, the ink of this embodiment may contain a UV-curable resin in an amount that cannot be described as a UV-curable ink.

[0053] The medium is, for example, the component with the highest mass percentage among the ingredients contained in the ink (before it is ejected). The mass percentage of the medium in the ink can be appropriately set, and can be less than 50% by mass or more than 50% by mass, for example, more than 50% by mass and less than 90% by mass. The medium can be water or an aqueous solvent, or an organic substance (e.g., an organic solvent), or a medium obtained by mixing the former and the latter. In the description of this embodiment, the case where the medium contains both water and an organic solvent is sometimes cited as an example. When the medium contains at least water, the mass percentage of water in the ink can be less than 50% by mass or more than 50% by mass, for example, more than 50% by mass and less than 70% by mass.

[0054] It should be noted that when describing the composition of the finished ink, unless otherwise specified, the percentage by mass refers to the mass in its state before spraying (before the medium, etc., evaporates).

[0055] When the medium contains water and an organic solvent, the composition and function of the organic solvent can be appropriately set. For example, the organic solvent may also contain alcohols (e.g., glycerol or ethylene glycol) and / or ethers (e.g., ethylene glycol ethers). Alcohols function, for example, as humectants that reduce the drying of the ink before it is ejected. Ethers are used, for example, to adjust the surface tension, viscosity, and / or drying speed of the ink. The mass ratio of water to organic solvent can also be appropriately set, and the mass percentage of either component can be greater than that of the other. For example, the mass percentage of water can be greater than that of the organic solvent; more specifically, the mass percentage of water in the medium can be set to 60% or more and 70% or less.

[0056] The colorant can be a pigment insoluble in the medium, a dye soluble in the medium (solvent), or a combination of both. The pigment and dye can be any known pigment and dye, or a pigment and dye obtained by applying such known pigments and dyes. For example, the pigment can be a pigment that is surface-coated to suppress agglomeration (so-called self-dispersing pigment), or a pigment that is not coated in this way. The percentage by mass of the colorant in the ink before ejection can be appropriately set. As an example of a range of this percentage by mass, it is 1% or more and 10% or less.

[0057] Multiple types of polymers, for example, include two or more polymers with a glass transition temperature (Tg) higher than room temperature. These two or more polymers include the fixer polymers already described. It should be noted that the ink may or may not contain polymers with a Tg lower than room temperature.

[0058] (Fixer polymer)

[0059] The fixing polymer melts upon heating, as described above. In other words, the fixing polymer exists as particles (solid) within the ink before heating (e.g., before ink is ejected). Therefore, the fixing polymer does not possess the property of being soluble in the medium (e.g., water-soluble) but is dispersed in the medium. Furthermore, the fixing polymer has a higher glass transition temperature (Tg) than the temperature of the ink before heating (e.g., room temperature and / or the temperature of the ink before ejection). Additionally, the fixing polymer has the property of remaining as a solid component to fix the colorant even after the ink has been heated. It should be noted that the fixing polymer can also serve functions other than fixing the colorant.

[0060] The Tg of the fixer polymer can be set relatively high compared to the Tg of other polymers in the ink. For example, the Tg of the fixer polymer can also be higher than the Tg of most (or all) of the polymers in the ink other than the fixer polymer, which have a Tg above room temperature. The term "most (or all)" can be, for example, 80% or more by mass, 90% or more by mass, or 95% or more by mass, or even 100% by mass. In the case of 100% by mass, in other viewpoints, the Tg of the fixer polymer is higher than the Tg of all polymers in the ink other than the fixer polymer. The term "most (or all) polymers" can contain only one type of polymer or two or more polymers.

[0061] The specific value of the Tg of the fixer polymer can be appropriately set. As an example of the range of the Tg of the fixer polymer, it is 70°C or higher and 120°C or lower (or 110°C or lower). Alternatively, as an example of the range of the difference between the Tg of the fixer polymer and the Tg of the aforementioned "most (or all) polymers", it is 40°C or higher and 60°C or lower.

[0062] It should be noted that, for example, the Tg of a fixer polymer is described as being higher than that of 80% or more of all polymers other than the fixer polymer that have a Tg higher than room temperature. Then, based on this premise, the difference between the Tg of the fixer polymer and the Tg of the aforementioned 80% or more polymers is 40°C or more and 60°C or less. In this case, the specific value of 80% or more of the former may differ from the specific value of 80% or more of the latter. For example, if the Tg of the fixer polymer is higher than that of 90% or more of all polymers other than the fixer polymer that have a Tg higher than room temperature, the polymers in that 90% or more whose Tg difference with the fixer polymer is 40°C or more and 60°C or less may only be a portion (e.g., only 80% or more of all polymers other than the fixer polymer that have a Tg higher than room temperature). The same applies to polymers with a Tg of 80% or more (or other mass percentages) when other conditions are added.

[0063] The percentage by mass of the fixer polymer in the ink can be appropriately set. For example, the percentage by mass of the fixer polymer in the ink can be smaller, equal to, or larger than the percentage by mass of any type of polymer, the total percentage by mass of all polymers other than the fixer polymer that have a Tg higher than room temperature, or the total percentage by mass of all polymers other than the fixer polymer. Alternatively, for example, the percentage by mass of the fixer polymer can be set to be 0.1 times, 0.3 times, or 0.5 times or more of the total percentage by mass of all polymers other than the fixer polymer that have a Tg higher than room temperature. As an example of a range for the percentage by mass of the fixer polymer, it is 1% by mass or more and 40% by mass or less.

[0064] The specific composition and / or components of the fixing polymer can be set as appropriate. For example, the fixing polymer can be a condensation polymer (e.g., a polyurethane polymer or a polyester polymer), an acrylic polymer, a styrene polymer, a styrene-acrylic polymer, a butadiene polymer, a styrene-butadiene polymer, a vinyl chloride polymer, or a methacrylic polymer. Some of the above can be understood as ethylene polymers. The Tg of these polymers can, for example, be in the temperature range of 70°C or higher and 120°C as described above.

[0065] Fixing polymers can be manufactured by combining two or more monomers that are the main components of the various polymers mentioned above (e.g., styrene, the main component of styrene-based polymers). In other words, fixing polymers can also be manufactured by combining monomers of polymers with different Tg values. In this case, by making a relatively large mass percentage of the monomers of the polymer with a relatively high Tg, the Tg of the fixing polymer can be increased. Conversely, by making a relatively large mass percentage of the monomers of the polymer with a relatively low Tg, the Tg of the fixing polymer can be decreased. That is, the Tg of the fixing polymer can be arbitrarily adjusted.

[0066] (Other polymers)

[0067] The physical properties and functions of polymers other than the fixer polymer contained in the ink can be appropriate. For example, these other polymers may or may not have the property of being soluble in a medium (solvent) (e.g., water solubility), regardless of whether the temperature gradient (Tg) is above room temperature. Furthermore, these other polymers may be liquid or solid before heating (e.g., before the ink is ejected). Additionally, these other polymers may be dispersant polymers used to disperse pigments (in other viewpoints, to inhibit agglomeration), or scrub-resistant polymers used to improve the ink's scrub resistance.

[0068] The percentage by mass of other polymers in the ink can be appropriately set. The relationship between the percentage by mass of other polymers and the percentage by mass of the fixer polymer is as described above. In the case of a range where the percentage by mass of all polymers other than the fixer polymer, or of all polymers other than the fixer polymer having a Tg higher than room temperature, is between 1% and 40% by mass.

[0069] As described above, at least one of the other polymers has a Tg higher than room temperature and a lower Tg than the fixing polymer. For example, the Tg of the dispersant polymer and / or the Tg of the scrub-resistant polymer may be higher than room temperature and a lower Tg than the fixing polymer. In this case, the proportion of the dispersant polymer or the scrub-resistant polymer in all polymers other than the fixing polymer that have a Tg higher than room temperature may be set to 80% or more by mass, 90% or more by mass, 95% or more by mass, or 100% by mass, or even less than the above. The specific value of the Tg of the polymer having a Tg higher than room temperature and a lower Tg than the fixing polymer can be an appropriate value. As an example of its range, it is 50°C or higher and less than 70°C.

[0070] The specific composition and / or materials of other polymers can be appropriately set. For example, any of the various compositions and / or materials (styrene-based polymers, etc.) exemplified as the specific composition and / or materials of other polymers (e.g., dispersant polymers and / or scrub-resistant polymers) can be used as the specific composition and / or materials of fixer polymers. However, in this case, the mass ratio of monomers in the manufacturing process differs between the other polymers and the fixer polymer. Similarly, the Tg of the other polymers, like the Tg of the fixer polymer, can be arbitrarily set by setting the mass percentage of the various monomers contained in the other polymers.

[0071] The structure of the dispersant polymer can be a known structure or a suitable structure. For example, the dispersant polymer can be a strip-shaped polymer. However, the dispersant polymer can also be granular. Additionally, for example, the dispersant polymer has a portion adsorbed onto the pigment and a portion exhibiting dispersibility. Dispersibility is manifested, for example, through steric hindrance, electrostatic repulsion, and / or conduction inhibition. The dispersant polymer is generally not needed when the pigment is self-dispersible, but it can be added to inks containing self-dispersible pigments. For example, the dispersant polymer contains styrene and butyl acrylate in a 70:30 ratio. In this case, the Tg of the dispersant polymer can be in the range of 50°C or higher and less than 70°C as described above.

[0072] The structure of the scrub-resistant polymer can be a known structure or a suitable structure. For example, the scrub-resistant polymer can be a polyester resin. In this case, the Tg of the scrub-resistant polymer can be in the range of 50°C or higher and less than 70°C as described above.

[0073] Ink may contain suitable ingredients in addition to the polymers mentioned above. For example, ink may also contain surfactants (in addition to dispersant polymers), humectants, surface tension modifiers, pH adjusters, and / or gloss enhancers. These additives may be composed of polymers or may form part of the medium (organic solvent).

[0074] (Conveying device)

[0075] The conveying device 5 has multiple rollers (e.g., 3A, 3B, 17A, 17B, 19A-19D) along the conveying path of the printed material 101. Each roller is a cylindrical or cylindrical member, arranged axially orthogonal to the conveying direction of the printed material 101, and its outer peripheral surface covers the entire width of the printed material 101, abutting against the surface or back of the printed material 101. Furthermore, at least one roller, including the recovery roller 3B, is rotated about an axis by a motor, thereby conveying the printed material 101. It should be noted that in this embodiment, the roller is rotated by a motor, but the roller can also be rotated by other drive sources or manually.

[0076] The number of rollers, their position relative to the conveying path, and their diameter can be appropriately set. In the illustrated example, the conveying device 5, in addition to the supply roller 3A and the return roller 3B, also includes, sequentially from the supply roller 3A side to the return roller 3B side, a first tension roller 19A, a second tension roller 19B, a first heating roller 17A, a second heating roller 17B, a third tension roller 19C, and a fourth tension roller 19D. Each roller except the return roller 3B can be driven to rotate by a motor or the like, or it can rotate passively only under the frictional force from the printed material 101.

[0077] The first heating roller 17A and the second heating roller 17B also serve as devices for promoting ink fixing relative to the printed material 101, as described in detail later, and also have the function of heating the printed material 101. The first tension roller 19A to the fourth tension roller 19D are used to apply tension to the printed material 101. In addition, in the illustrated example, the first tension roller 19A to the fourth tension roller 19D are also used to ensure that the printed material 101 is in close contact with the first heating roller 17A and the second heating roller 17B, thereby improving the heating efficiency.

[0078] More specifically, for example, the first heating roller 17A abuts against the back side of the workpiece 101 at a position upstream of the ink ejection device 7. The second tension roller 19B is located upstream of the first heating roller 17A without any other rollers sandwiched between it and the first heating roller 17A, and abuts against the surface of the workpiece 101 (in other words, the side opposite to the side abutting against the first heating roller 17A). The first tension roller 19A is located upstream of the second tension roller 19B without any other rollers sandwiched between it and the second tension roller 19B, and abuts against the back side of the workpiece 101 (in other words, the side opposite to the side abutting against the second tension roller 19B). At least one of the first tension roller 19A and the second tension roller 19B is forced towards the workpiece 101 by a force-applying component (e.g., a spring and / or actuator, not shown). Thus, tension is applied to the workpiece 101, and the workpiece 101 is pressed tightly against the first heating roller 17A.

[0079] Additionally, for example, the second heating roller 17B abuts against the back side of the printed object 101 at a position downstream of the ink ejection device 7. The third tension roller 19C is located downstream of the second heating roller 17B without any other rollers sandwiched between it and the second heating roller 17B, and abuts against the surface of the printed object 101 (in other words, the side opposite to the side abutting against the second heating roller 17B). The fourth tension roller 19D is located downstream of the third tension roller 19C without any other rollers sandwiched between it and the third tension roller 19C, and abuts against the back side of the printed object 101 (in other words, the side opposite to the side abutting against the third tension roller 19C). At least one of the third tension roller 19C and the fourth tension roller 19D is forced towards the printed object 101 by a force-applying component (e.g., a spring and / or actuator, not shown). This imparts tension to the printed object 101, and furthermore, the printed object 101 adheres tightly to the second heating roller 17B.

[0080] The first heating roller 17A and / or the second heating roller 17B have relatively large diameters. This increases the contact area between these heating rollers and the printed material 101, improving heating efficiency. For example, the diameter of the first heating roller 17A is larger than the diameter of the first tension roller 19A and / or the diameter of the second tension roller 19B. Similarly, the diameter of the second heating roller 17B is larger than the diameter of the third tension roller 19C and / or the fourth tension roller 19D. The diameter of the first heating roller 17A and / or the diameter of the second heating roller 17B is larger than the diameter of all other rollers included in the conveying device 5.

[0081] Viewed from the side, the straight line formed by the printed object 101 between the second tension roller 19B and the first heating roller 17A can be inclined relative to the straight line formed by the printed object 101 between the first heating roller 17A and the next roller (the second heating roller 17B in the illustrated example). The inclination angle can be relatively large. Therefore, the range of angles around the axis of the first heating roller 17A where the printed object 101 is in close contact with it becomes larger. For example, the inclination angle can be set to 45° or more, 70° or more, or 90° or more. The relationship between the straight line formed by the printed object 101 between the third tension roller 19C and the second heating roller 17B and the straight line formed by the printed object 101 between the second heating roller 17B and the previous roller (the first heating roller 17A in the illustrated example) is also the same.

[0082] The roller configuration can be various other than those described above. For example, the surfaces of the workpiece 101 that the first heating roller 17A, the first tension roller 19A, and the second tension roller 19B abut against can be opposite to the example shown. The second tension roller 19B can be provided instead of the first tension roller 19A. The third tension roller 19C can be provided instead of the fourth tension roller 19D. The first to fourth tension rollers 19A can be omitted. Rollers other than those shown in the example can also be provided. For example, multiple rollers arranged on a curve with the upper side convex in side view and abutting the back of the workpiece 101 can be provided between the first heating roller 17A and the second heating roller 17B.

[0083] The movement scheme of the printed object 101 can be appropriately set according to the scheme of the ink ejection device 7, etc. For example, the conveying device 5 can make the printed object 101 move continuously or intermittently. In addition, when the printed object 101 moves continuously, the conveying speed of the printed object 101 can be constant or variable. It should be noted that intermittent movement is movement accompanied by speed variation in other viewpoints. The specific value of the conveying speed of the printed object 101 can be appropriately set. When giving examples of the range of conveying speed (for example, average speed in the case of speed variation), it is 50 m / min or more and 300 m / min or less, or 100 m / min or more and 200 m / min or less.

[0084] (Ink ejection device)

[0085] The ink ejection device 7 has at least one (20 in the illustrated example) head 21 that is opposite to the printed object 101 and directly bears the responsibility of ejecting ink.

[0086] It should be noted that, in the descriptions relating to the position of the ink ejection device 7 in this invention, references may be made to the position of the head 21, the position of the ejection surface 21a (described later), or the position of the arrangement area of ​​the plurality of nozzles 21b (described later). In other words, in the descriptions relating to the position of the ink ejection device 7, the term "ink ejection device 7" may be appropriately replaced with the terms "head 21," "ejection surface 21a," or "arrangement area of ​​the plurality of nozzles 21b."

[0087] In this embodiment, the head 21 is basically fixed in a direction that intersects the transport direction of the printed material 101, and the printing apparatus 1 is called a line printer. However, the printing apparatus may also be a so-called serial printer that alternately performs the action of ejecting droplets while moving the head 21 in a direction that intersects the transport direction of the printed material 101 (e.g., a substantially orthogonal direction) with the transport of the printed material 101.

[0088] The head 21 is held in a manner such that the ink ejection surface 21a (the lower surface in the illustrated example) is positioned substantially parallel to the workpiece 101. The distance between the ejection surface 21a and the workpiece 101 can be appropriately set. For example, this distance is 0.5 mm or more and 20 mm or less, or 0.5 mm or more and 2 mm or less. The shape of the head 21 in top view (the shape of the ejection surface 21a) can be appropriately shaped, for example, as an elongated shape (more specifically, a roughly rectangular shape) in the direction intersecting the transport direction of the workpiece 101. The direction intersecting the transport direction is, for example, a direction substantially orthogonal to the transport direction, and is sometimes referred to as the width direction of the workpiece 101 (hereinafter, the same).

[0089] Multiple heads 21, for example Figure 2 The configuration shown constitutes at least one (four in the illustrated example) head group 23. Each head group 23 includes a plurality of (five in the illustrated example) heads 21. The plurality of heads 21 included in each head group 23 are arranged in the width direction of the printed matter 101 such that they are connected to each other in the printable range of the heads 21 or overlap at their ends. Thus, printing without gaps in the width direction of the printed matter 101 is possible.

[0090] In the illustrated example, more specifically, in each head group 23, three of the five heads 21 are arranged in the width direction of the printed material 101. The remaining two heads 21 are arranged in the width direction of the printed material 101 at positions offset relative to the aforementioned three heads 21 in the transport direction, and are respectively located between the aforementioned three heads 21 in the width direction of the printed material 101. Alternatively, in each head group 23, the multiple heads 21 are arranged in an alternating pattern.

[0091] Four head units 23 are arranged along the transport direction of the printed material 101. From ink cartridge 25 ( Figure 1 Ink is supplied to each head 21. Ink of the same color is supplied to heads 21 belonging to the same head group 23, enabling the printing of four colors of ink using four head groups 23. The colors of the ink ejected from each head group 23 are, for example, magenta (M), yellow (Y), cyan (C), and black (K). By causing such ink to drip onto the workpiece 101, color images can be printed.

[0092] Regarding the number of heads 21 mounted on the printing apparatus 1, if the area that can be printed by one head 21 is to be printed in a single color, then one head 21 can be used. The number of heads 21 included in the head group 23 and the number of head groups 23 can be appropriately changed according to the printing material 101 and the printing conditions. For example, the number of head groups 23 can be increased to print more colors. In addition, if multiple head groups 23 that print in the same color are arranged and printed alternately along the transport direction, the transport speed can be increased even if heads 21 with the same performance are used. As a result, the printing area per unit time can be increased. In addition, multiple head groups 23 that print in the same color can be prepared and arranged staggered in a direction intersecting the transport direction to improve the resolution in the width direction of the printing material 101.

[0093] Furthermore, in addition to printing colored inks, liquids such as coating agents can be uniformly or patternedly printed using the head 21 for surface treatment of the printed object 101. For example, when using a printed object that is difficult for liquid to penetrate as the printed object 101, a coating agent that forms a liquid-retaining layer can be used to facilitate ink fixing. Furthermore, when using a printed object that is easily penetrated by liquid as the printed object 101, a coating agent that forms a liquid penetration-inhibiting layer can be used to prevent excessive liquid seepage and minimal mixing with other adjacent drips. It should be noted that the coating agent can be applied using the aforementioned coating machine (not shown) instead of printing based on the head 21, or based on printing based on the head 21.

[0094] Although not specifically illustrated, multiple heads 21 can be housed in the head chamber. The head chamber, for example, is configured as a space substantially isolated from the outside. Furthermore, the head chamber has an inlet allowing the printed material 101, conveyed by the transport device 5, to enter, and an outlet allowing the printed material 101, conveyed by the transport device 5, to exit. The printed material 101 is inked by the heads 21 within the head chamber. Within the head chamber, compared to the outside, variations in factors affecting ink adhesion are more easily reduced. Such factors include, for example, temperature, humidity, and air pressure. At least one of these various factors within the head chamber can also be actively controlled by appropriate means.

[0095] The way in which the ink droplets are ejected from the head 21 can be configured to be appropriate. For example, the head 21 can be configured as a piezoelectric head that uses a piezoelectric actuator to apply pressure to the ink inside the head 21 to eject droplets. Alternatively, the head 21 can also be configured as a thermal head that heats the ink to generate bubbles and ejects droplets under the pressure associated with the generation of these bubbles.

[0096] (A device for fixing ink onto the printed material)

[0097] The printing apparatus 1, as described above, has multiple devices that promote the fixing of ink ejected from the ink ejection device 7 and dripped onto the printable material 101 relative to the printable material 101. These multiple devices include, for example, a drying device 9, a melting device 11, and an auxiliary melting device 13. These devices generally promote ink fixing by heating the ink. However, the specific structure, heating amount, and / or location of these devices differ. Consequently, these devices exert different effects on the ink and / or influence each other in their effects.

[0098] (Drying device)

[0099] The drying apparatus 9 promotes the evaporation of the ink medium, for example, by heating the printable surface 101. The heating of the printable surface 101 by the drying apparatus 9 can be performed before the ink adheres to the printable surface 101, after adhesion, or both. When the drying apparatus 9 heats the printable surface 101 after the ink has adhered, it can heat the printable surface 101 from the back side (without directly heating the ink), or from the surface side (or directly heat the printable surface 101 together with the ink), or heat the printable surface 101 from both the back side and the surface side.

[0100] In other viewpoints, the drying device 9 may have a portion located upstream of the ink ejection device 7 in the transport direction of the printed material 101, a portion located at the same position as the ink ejection device 7, a portion located downstream of the ink ejection device 7, or portions integrally or dispersedly located in two or more of the above three positions. Furthermore, the drying device 9 may have a portion located on the surface side of the printed material 101, a portion located on the back side, or both. For example, the drying device 9 may have a portion located upstream of the ink ejection device 7, rather than at the same position. In this case, for example, it is possible to heat the printed material 101 and the ink while suppressing turbulence that occurs in the space at the same position as the ink ejection device 7, thus reducing the ink ejection stability.

[0101] It should be noted that, in the descriptions relating to the position of the drying device 9 in this invention, for example, reference can be made to the position of the portion of the drying device 9 directly used for heating the printed material 101 (e.g., the outer peripheral surface of the heating roller or the air outlet for delivering hot air), or the position of the portion of the printed material 101 heated by the drying device 9 (e.g., the portion abutting against the roller or the portion to which hot air is blown). In other words, in the descriptions relating to the position of the drying device 9, the term "drying device 9" can be appropriately replaced with the term "the portion directly used for heating" or "the portion of the printed material 101 that is heated."

[0102] The drying apparatus 9 heats the printed material 101 substantially uniformly in the width direction (the heating amount is constant in the width direction). Consequently, the temperature distribution of the printed material 101 in the width direction is substantially uniform. However, the drying apparatus 9 can also vary the heating amount in the width direction of the printed material 101. For example, the heating amount can be relatively large on both sides of the width direction where heat dissipation is easier. The length of the printed material 101 that the drying apparatus 9 can simultaneously heat in the transport direction can be arbitrarily set.

[0103] The drying apparatus 9 can have various structures. In this embodiment, the drying apparatus 9 has a first heating roller 17A. The first heating roller 17A abuts against the back of the workpiece 101 at a position upstream of the ink ejection device 7, as described above.

[0104] More specifically, the first heating roller 17A contacts the printed material 101 only a portion of its outer circumferential surface around its axis. Furthermore, the first heating roller 17A does not slide substantially with the printed material 101, but rather rotates actively or passively as the printed material 101 moves. Therefore, it can be understood that the first heating roller 17A has a first portion 17a and a second portion 17b of the printed material 101 heated at different positions around its axis, and that the first portion 17a and the second portion 17b alternately contact the printed material 101.

[0105] The specific structure of the first heating roller 17A can be various, such as a known structure or a structure obtained by applying that known structure. For example, although not specifically illustrated, the first heating roller 17A can be configured to have an internal heating wire, and heat is generated according to Joule's law by allowing current to flow through the heating wire. Alternatively, for example, the first heating roller 17A can have an internal induction coil, and heat is generated by induction heating. Furthermore, for example, the first heating roller 17A can be configured to have a flow path for supplying the heated medium from the outside. The cylindrical or cylindrical substrate of the first heating roller 17A can be made of suitable materials such as ceramic and / or metal.

[0106] (Melting apparatus)

[0107] The melting device 11 heats the ink, for example, by irradiating it with UV light onto the ink adhered to the printable surface 101. This heating melts the fixer polymer (or, in other views, a glass component) within the ink, as described above. The molten fixer polymer then solidifies, thereby fixing the colorant within the ink onto the printable surface 101. It should be noted that UV light can irradiate the printable surface 101 at locations where the ink is not present, or UV light can partially penetrate the ink to irradiate the printable surface 101. The printable surface 101 can be a material that substantially allows UV light to pass through, or a material that absorbs at least a portion of the UV light and generates heat.

[0108] The melting device 11 irradiates the ink with UV light, and is therefore located downstream of the ink ejection device 7 in the transport direction of the printed object 101. It is also located on the surface side of the printed object 101 and faces that surface. The relative positions (distances) of the ink ejection device 7 and the melting device 11 in the transport direction of the printed object 101 can be appropriately set. For example, they can be arranged with a gap between them, or they can be arranged adjacent to each other with (almost) no gap.

[0109] It should be noted that, in the descriptions relating to the position of the melting device 11 in this invention, for example, reference can be made to the position of the UV outlet (the foremost part of the optical system) in the melting device 11, or the position of the UV-irradiated area in the printed material 101. In other words, in the descriptions relating to the position of the melting device 11, the term "melting device 11" can be appropriately replaced with the term "UV outlet" or "UV-irradiated area in the printed material 101".

[0110] UV irradiation by the melting device 11 can begin, for example, after the heating of the printed material 101 by the drying device 9 has been completed. Alternatively, in other viewpoints, the melting of the fixer polymer within the ink can begin during the evaporation of the medium within the ink, or after the medium has completely evaporated. It should be noted that even when the medium is considered to have completely evaporated, a trace amount of medium may practically remain. For example, if the ink just before UV irradiation begins contains less than 5% by mass of medium equivalent to the ink before spraying, it can be understood that the medium has completely evaporated.

[0111] In other viewpoints, the melting device 11 may be located downstream of the drying device 9 in the conveying direction of the printed material 101. In this case, the relative positions (distances) of the drying device 9 and the melting device 11 in the conveying direction of the printed material 101 can be appropriately set. For example, they may be arranged spaced apart from each other, or they may be arranged adjacent to each other without any spacing.

[0112] The melting device 11, for example, is capable of irradiating UV light across the entire width of the area that can be printed by the ink ejection device 7. For example, the melting device 11 has a length that covers the entire width of the printable material 101 or the entire width of the printable area, and simultaneously irradiates UV light within that width. However, the melting device 11 may also differ from the illustrated example by irradiating UV light across the entire width of the printable area by moving along the width direction of the printable material 101.

[0113] The melting device 11 irradiates UV light approximately uniformly along the width of the printable material 101. In other words, the energy of the UV light irradiating the printable material 101 (and the ink) per unit time is approximately constant along the width of the printable material 101. It should be noted that the amount of UV absorption by the printable material 101 (and the ink) is affected by the distribution of the ink along the width. Therefore, the amount of heat generated by UV heating is not necessarily uniform along the width. It should also be noted that the melting device 11 may differ from the above, allowing for varying UV irradiation amounts along the width of the printable material 101.

[0114] In the printed object 101, the shape of the area irradiated with UV light is, for example, a rectangle with sides parallel to both the transport direction and the width direction of the printed object 101. It should be noted that the area irradiated with UV light can also be a shape other than a rectangle. In the width direction of the printed object 101, the length of the area irradiated with UV light is, as described above, the entire width of the area that the ink ejection device 7 can print. Furthermore, in the transport direction of the printed object 101, the length of the area irradiated with UV light can be appropriately set.

[0115] The specific structure of the melting device 11 can be configured to be suitable. For example, the melting device 11 may have at least a light source 11a that generates UV light. Furthermore, the melting device 11 may also have a reflector that reflects UV light leaking from the light source 11a to the side opposite to the printed material 101, a narrowed section with an opening that adjusts the shape of the cross-section of the UV light from the light source 11a, and / or a lens that focuses the UV light. Even with such elements, the light source 11a can be defined simply as the melting device 11. The light source 11a may be composed of suitable elements such as an LED (light emitting diode), an incandescent lamp, a fluorescent lamp, or a mercury lamp. The light source 11a may have only one of the aforementioned elements, or it may have multiple of the aforementioned elements. It may also be a surface light source composed of multiple elements (e.g., LEDs).

[0116] UV light, as is known, is light with a wavelength shorter than visible light, for example, between 10 nm and 400 nm. The UV light radiated by the melting device 11 can be near-ultraviolet or far-ultraviolet. Near-ultraviolet light can also be any of the so-called UV-A, UV-B, and UV-C. In other words, the wavelength of the UV light radiated by the melting device 11 can be appropriately set. The UV light radiated by the melting device 11 can be a UV light with a narrow wavelength range of energy distribution, such as laser light, or a UV light with a wide wavelength range of energy distribution. The aforementioned wavelength range in this invention can, for example, refer to the wavelength where the energy becomes the peak value (or the highest peak value if there are multiple peak values).

[0117] The intensity of the UV radiation irradiated by the melting device 11 onto the printed material 101 (and the ink) can be appropriately set. It should be noted that, in this invention, the UV intensity is the energy per unit time of UV radiation irradiating a unit area of ​​the printed material 101. The UV intensity can, for example, be higher than the intensity of UV radiation required to cure UV-curable inks. For example, the UV intensity used to cure UV-curable inks is typically less than 10 W / cm². 2 In contrast, the intensity of the UV from the melting device 11 can be set to 10 W / cm². 2 Above, 20W / cm 2 Above or 30W / cm 2 That's all. However, it is also possible that, unlike the above, the intensity of the UV from the melting device 11 is lower than the intensity of the UV used to cure the UV-curable ink.

[0118] The cumulative UV light intensity irradiated by the melting device 11 onto the printed material 101 (and the ink) can be appropriately set. It should be noted that the cumulative light intensity is a value obtained by integrating the intensity over time. For example, the cumulative UV light intensity can be greater than the cumulative UV light intensity required to irradiate the printed material for curing UV-curable inks. For instance, the cumulative UV light intensity required to irradiate the printed material for curing UV-curable inks is typically less than 500 mJ / cm². 2 In contrast, the cumulative UV light intensity irradiated by the melting device 11 onto the printed material 101 can be set to 500 mJ / cm². 2 Above, 1000mJ / cm 2 Above, 1500mJ / cm 2 Above 5000mJ / cm 2 Above or 10000 mJ / cm 2 That's all. However, it is also possible that, unlike the above, the cumulative amount of UV light irradiated by the melting device 11 onto the printed object 101 may be less than the cumulative amount of UV light required to irradiate the printed object in order to cure the UV-curable ink.

[0119] (Auxiliary melting device)

[0120] The auxiliary melting device 13 is located on the opposite side of the melting device 11 relative to the printable material 101, and assists in melting the fixer polymer by heating the back side of the printable material 101. Since the auxiliary melting device 13 assists in melting the fixer polymer, the position of the melting device 11 can be referenced regarding its position in the transport direction of the printable material 101. For example, the auxiliary melting device 13 may also be positioned downstream of the ink ejection device 7 and the drying device 9.

[0121] It should be noted that, similar to the drying device 9, in descriptions related to the location of the auxiliary melting device 13, for example, reference can be made to the location of the portion of the auxiliary melting device 13 directly used for heating the printed material 101, or the location of the portion of the printed material 101 heated by the auxiliary melting device 13. In other words, in descriptions related to the location of the auxiliary melting device 13, the term "auxiliary melting device 13" can be appropriately replaced with the term "the portion directly used for heating," or "the portion of the printed material 101 that is being heated."

[0122] When viewed from above, at least a portion of the area of ​​the printed material 101 heated by the auxiliary melting device 13 overlaps with at least a portion of the area of ​​the printed material 101 irradiated with UV by the melting device 11. These two areas may be substantially contiguous or not. For example, the entire area irradiated with UV may overlap with a portion or all of the area heated by the auxiliary melting device 13. In this case, as understood from the effects described later, the energy of the UV radiation can be efficiently utilized for melting the fixing polymer.

[0123] The auxiliary melting device 13 heats the printable 101 approximately uniformly in the width direction (the heating amount is constant in the width direction). However, the auxiliary melting device 13 can also vary the heating amount in the width direction of the printable 101. For example, the heating amount can be relatively large on both sides of the width direction where heat dissipation is easier. The length of the printable 101 that the auxiliary melting device 13 can heat simultaneously in the transport direction of the printable 101 can be arbitrarily set.

[0124] The auxiliary melting device 13 can have various structures. In this embodiment, the auxiliary melting device 13 has the second heating roller 17B described above. The structure of the second heating roller 17B can be the same as or different from the structure of the first heating roller 17A. In either case, the above description related to the structure of the first heating roller 17A (having a first part and a second part, and may have a heating wire, an induction coil, or a flow path, etc.) can be appropriately referenced to the second heating roller 17B.

[0125] (Head of the ink ejection device)

[0126] The basic structure of the head 21 of the ink ejection device 7 can be a known structure or a structure obtained by applying that known structure, etc. Additionally, in this embodiment, the head 21 may also have a heater for heating the ink before ejection. By preheating the ink before ejection, for example, the time required for the evaporation of the medium and / or the melting of the fixer polymer in the ink after ejection can be reduced. The structure of the heater in the head 21 can be configured appropriately. An example of a heater provided in the head 21 is shown below.

[0127] Figure 3A This is a three-dimensional view of the head 21 obtained from above (on the side opposite to the printed object 101). Figure 3B This is a three-dimensional view obtained by observing head 21 from below (the side of the printed object 101). Figure 3C This is a three-dimensional view obtained by observing a part of the head 21 (head body 27) from above.

[0128] The head 21, for example, has a head body 27 and a back member 29 fixed above the head body 27. The head body 27 has an ejection surface 21a opposite to the workpiece 101. Multiple nozzles 21b are opened in the ejection surface 21a for ejecting ink droplets. For example, the head body 27 is the component directly related to the ejection of the droplets. On the other hand, the back member 29 serves, for example, as an intermediary between the head body 27 and other components (e.g., the ink cartridge 25 and the control device 15). The head 21 may also have suitable components (e.g., a housing covering the back member 29) in addition to the above.

[0129] Although not specifically illustrated, the head body 27 has multiple individual flow paths that communicate individually with multiple nozzles 21b, and a common flow path that communicates with the multiple individual flow paths and extends along the ejection surface 21a. On the side of the head body 27 opposite to the ejection surface 21a, there is, for example, an opening 27a that communicates individually or commonly with the ends of one or more common flow paths. In the case that the head 21 is piezoelectric, an actuator substrate 30 including multiple piezoelectric actuators that individually apply pressure to the multiple individual flow paths can be provided on the side of the head body 27 opposite to the ejection surface 21a.

[0130] The back member 29 has, for example, one or more openings 29a communicating with the ink cartridge 25 via a tube (not shown) and a flow path (not shown) connecting the openings 29a to the openings 27a of the head body 27. In addition, although not specifically shown, the back member 29 houses a driver that supplies power to the head body 27 (e.g., actuator substrate 30) and a circuit board on which the driver is mounted.

[0131] Figure 3D yes Figure 3C A magnified view of region IIId.

[0132] The head body 27 has multiple plates 31 stacked on top of each other. A nozzle 21b and a flow path communicating with the nozzle 21b are formed by forming through holes or the like in the multiple plates 31. The plates 31 are made of, for example, metal or resin.

[0133] In the first 21 of such a structure, for example, Figure 3A As shown, a heater 33A can be provided on the upper surface of the back member 29. The heater 33A can be, for example, a sheet-shaped heater (film heater). The heater 33A is constructed, for example, by using a sheet-shaped insulator to clamp an electric heating wire that extends appropriately in a plane. The top view shape and size of the heater 33A can be appropriately set.

[0134] Alternatively, for example, heater 33A can be used as a basis for or in place of heater 33A, such as Figure 3D As shown, a sheet-like heater 33B is sandwiched between multiple plates 31. Like heater 33A, heater 33B is constructed, for example, by using a sheet-like insulator to sandwich a heating wire that extends appropriately in a plane. The top view shape and dimensions of heater 33B can be appropriately set. For example, heater 33B can have a width that covers the entire nozzle 21b when viewed from above.

[0135] Although not specifically illustrated, heaters may be provided on the upper surface of the back member 29 and / or inside the head body 27, or in place of the upper surface of the back member 29 and / or inside the head body 27, on the side of the head 21 (the surface intersecting the D1 or D2 direction), inside the back member 29, and / or between the head body 27 and the back member 29. The heater is not limited to a sheet-like heater; for example, it may be a heater with a thickness that cannot be conceived as sheet-like. Furthermore, the head 21 may have a flow path for the flow of a heating medium, either based on or in place of a heater.

[0136] (Control device)

[0137] Control device 15 ( Figure 1 For example, although not specifically illustrated, it is configured to include a CPU (central processing unit), ROM (read-only memory), RAM (random access memory), and external storage devices. In other words, the control device 15 is configured, for example, to include a computer. The CPU constructs the various functional units described later by executing programs stored in ROM and / or external storage devices. In addition, the control device 15 may also include logic circuits that only perform constant operations, or it may be conceptualized as including drivers that supply power to various elements.

[0138] The control device 15 can also be appropriately distributed in hardware. For example, the control device 15 can also be configured to include multiple lower-level control devices and one upper-level control device. The multiple lower-level control devices are individually provided in the conveying device 5, the ink ejection device 7, the drying device 9, the melting device 11, and the auxiliary melting device 13. The upper-level control device controls the multiple lower-level control devices (e.g., to achieve synchronization) by sending and receiving signals between the multiple lower-level control devices.

[0139] (Structure of a signal processing system)

[0140] Figure 4 This is a block diagram showing the structure of the signal processing system of the printing apparatus 1.

[0141] The control unit 15 has various functional units (e.g., 35, 37, 39, 41, 43, and 45) constructed by executing programs via a CPU. The head control unit 35 controls the head 21. The conveying speed control unit 37 controls the conveying device 5. The first temperature control unit 39 controls the drying device 9 (in other words, the first heating roller 17A). The head temperature control unit 41 controls the head heaters 33 (33A and / or 33B) of the head 21. The second temperature control unit 43 controls the auxiliary melting device 13 (in other words, the second heating roller 17B). The UV control unit 45 controls the melting device 11. More specifically, for example, as follows.

[0142] (Head control unit)

[0143] The head control unit 35 generates information corresponding to the size of the droplets that should be ejected by each nozzle 21b at an ejection period that arrives at a predetermined cycle, based on data including information containing images (text is also a type of image), and outputs this information to a driver (not shown) of the head 21. The driver (not shown) inputs a voltage corresponding to the input information to the drive element (e.g., a piezoelectric actuator) of each nozzle 21b. It should be noted that the head control unit 35 can also be conceptualized as including a driver. The ejection cycle can be a constant value set by the manufacturer of the printing apparatus 1, or it can be a value set by the head control unit 35 based on predetermined information. The predetermined information mentioned above is, for example, the resolution in the transport direction of the printed material 101 set by the manufacturer or user, and / or the transport speed of the printed material 101 set by the manufacturer or user. For example, when printing on a printed material 101 transported at a speed of 100 m / min using a 1200 dpi head 21, it is possible to control the operation to operate at a drive frequency of 78.74 kHz and eject ink.

[0144] (Conveyor Speed ​​Control Department)

[0145] The transport speed control unit 37 controls the transport device 5, for example, to maintain the transport speed of the printed material 101 at a target value. This target value is substantially constant, for example, during the operation of the printing apparatus 1 (or during printing in other respects; the same applies below). Furthermore, the target value can be a constant value set by the manufacturer of the printing apparatus 1, a value set by the user, or a value set by the transport speed control unit 37 based on specified information. The specified information mentioned above includes, for example, the resolution in the transport direction of the printed material 101 set by the manufacturer or the user, and / or the droplet ejection cycle set by the manufacturer or the user.

[0146] The conveyor speed control unit 37 can perform feedback control based on the detection value of the speed sensor 47, which detects the speed of the printed material 101 (as illustrated in the example), or it can perform open-loop control without feedback. The speed sensor 47 can detect the speed of the printed material 101 itself, or it can detect the speed of the element driving the printed material 101. For example, a speed sensor that detects speed based on image recognition, such as an optical mouse, can be used for the former. For the latter, a sensor that detects the rotation of the rollers of the conveyor 5 or the motor driving the rollers (e.g., an encoder or a rotary transformer) can be used. By using these, it is possible to synchronize the speed of the printed material 101 with the timing of the ejection from the head 21.

[0147] The conveying speed control unit 37 supplies power, for example, to at least one motor that rotates at least one roller of the conveying device 5 via a driver (not shown). It should be noted that the conveying speed control unit 37 can also be conceptually designed to include a driver. The driver can be a driver that performs feedback control of the motor (a lower-level feedback control than the aforementioned feedback control) or a driver that performs open-loop control of the motor.

[0148] (First Temperature Control Unit)

[0149] The first temperature control unit 39 controls the drying device 9, for example, to maintain the temperature of a predetermined area of ​​the printed material 101 at a target value. The predetermined area is, for example, the temperature of a region in the printed material 101 heated by the drying device 9. However, the predetermined area could also be other areas in the printed material 101 where heating by the drying device 9 is dominant in terms of temperature change. For example, the predetermined area could also be a region downstream of the region heated by the drying device 9 and a region not heated by other devices (e.g., in...). Figure 1 In the example, this is the area opposite to the ink ejection device 7.

[0150] The target temperature value is kept substantially constant during the operation of the printing apparatus 1, for example. Alternatively, the target value can be a fixed value set by the manufacturer of the printing apparatus 1, a value set by the user, or a value set by the first temperature control unit 39 based on specified information. The specified information may include, for example, ink-related information input by the manufacturer or user (e.g., information that can determine the Tg of a specified polymer), the transport speed of the printed material 101 set by the manufacturer or user, and / or the relative position (distance) of the drying device 9 to other devices (e.g., 7, 11, and / or 13) input by the manufacturer or user.

[0151] The first temperature control unit 39 can perform feedback control based on the detection value of the first temperature sensor 49, which detects the temperature of a specified area of ​​the printed material 101 (as illustrated in the example), or it can perform open-loop control without feedback. The first temperature sensor 49 can detect the temperature of the printed material 101 itself, the ambient temperature near the printed material 101, or the temperature of an appropriate part of the drying apparatus 9 (e.g., the surface or interior of the first heating roller 17A). In either case, the first temperature sensor 49 can be a non-contact temperature sensor or a contact temperature sensor. Examples of non-contact temperature sensors include radiation thermometers and thermal imagers. Examples of contact temperature sensors include thermocouples, thermistors, and resistive temperature sensors. The detected temperature can be directly compared with a target value, or it can be compared with a target value after appropriate corrections (e.g., conversion to a temperature at a location different from the sensor's position).

[0152] Specifically, the control of the drying apparatus 9 is, for example, the control of the electrical power supplied to the heat-generating elements (e.g., heating wires or induction coils) via a driver (not shown). More specifically, the voltage, current, and / or frequency (in the case of AC) can be controlled according to the type of heat-generating elements. It should be noted that the first temperature control unit 39 can also be conceptually included with a driver. Furthermore, the control of the drying apparatus 9 can also be other than the above-described control. For example, in a structure that supplies a heat medium to the first heating roller 17A, the flow rate of the heat medium can also be controlled.

[0153] (Head temperature control unit)

[0154] The head temperature control unit 41 controls the head heater 33 in a manner that maintains the temperature of the ink held at a predetermined location on the head 21 at a target value. The predetermined location may be either the head body 27 or the back panel member 29, or any location within these members (in other words, any flow path). However, if the predetermined location is within or near the nozzle 21b, the accuracy of fixing the ink 103 relative to the printed material 101 is improved.

[0155] The target temperature value is kept substantially constant during the operation of the printing apparatus 1, for example. Alternatively, the target value can be a fixed value set by the manufacturer of the printing apparatus 1, a value set by the user, or a value set by the head temperature control unit 41 based on specified information. This specified information may be, for example, ink-related information input by the manufacturer or user (e.g., information that can determine the Tg of a specified polymer).

[0156] The head temperature control unit 41 can perform feedback control based on the detection value of the head temperature sensor 51, which detects the temperature of the ink (as illustrated in the example), or it can perform open-loop control without feedback. The head temperature sensor 51 can detect the temperature of the ink itself while exposed within the flow path, or it can detect the temperature of the head 21 while not exposed within the flow path. In the former case, a contact temperature sensor can be used, for example. In the latter case, a contact or non-contact temperature sensor can be used, for example. The specifics of contact or non-contact temperature sensors are as described above. The detected temperature can be directly compared with a target value, or it can be compared with a target value after appropriate corrections (e.g., conversion to a temperature at a location different from the sensor's position).

[0157] The control of the head heater 33 specifically refers to the control of the power supplied to the head heater 33 via a driver (not shown). More specifically, the voltage, current, and / or frequency (in the case of AC) can be controlled depending on the specific structure of the head heater 33. It should be noted that the head temperature control unit 41 can also be conceptually conceived as including a driver.

[0158] (Second Temperature Control Unit)

[0159] The second temperature control unit 43 controls the auxiliary melting device 13, for example, to maintain the temperature of a specified area of ​​the printed material 101 at a target value. The specified area is, for example, the temperature of the region in the printed material 101 heated by the auxiliary melting device 13.

[0160] The target temperature value is kept substantially constant during the operation of the printing apparatus 1, for example. Alternatively, the target value can be a fixed value set by the manufacturer of the printing apparatus 1, a value set by the user, or a value set by the second temperature control unit 43 based on specified information. This specified information may be, for example, ink-related information input by the manufacturer or user (e.g., information that can determine the Tg of a specified polymer).

[0161] The second temperature control unit 43 can perform feedback control based on the detection value of the second temperature sensor 53, which detects the temperature of a specified area of ​​the printed material 101 (as illustrated in the example), or it can perform open-loop control without feedback. The second temperature sensor 53 can detect the temperature of the printed material 101 itself, the ambient temperature near the printed material 101, or the temperature of an appropriate part of the auxiliary melting device 13 (e.g., the surface or interior of the second heating roller 17B). In either case, the second temperature sensor 53 can be a non-contact temperature sensor or a contact temperature sensor. The specifics of contact and non-contact temperature sensors are as described above. The detected temperature can be directly compared to a target value, or it can be compared to a target value after appropriate corrections (e.g., conversion to a temperature at a location different from the sensor's position).

[0162] The auxiliary melting device 13 can, for example, perform an operation to raise the temperature of the printed object 101 (and the ink) to a predetermined temperature. The predetermined temperature can be, for example, set as the temperature of most (or all) of the polymers contained in the ink (excluding the fixer polymer) having a Tg higher than room temperature but lower than the Tg of the fixer polymer. Regarding "most (or all)," as described above. The melting device 11 can perform an operation to raise the temperature of the ink by UV irradiation to a temperature higher than the predetermined temperature (the target temperature of the auxiliary melting device 13) (e.g., a temperature higher than the Tg of the fixer polymer). When performing such an operation, and the heating of the ink by the melting device 11 has a significant impact on the temperature of the printed object 101, the control of the auxiliary melting device 13 can, for example, be configured to prevent the temperature of the printed object 101 itself from approaching the target temperature, and instead ensure that the detected temperature of an appropriate part of the auxiliary melting device 13 (including the case where the detected temperature is converted to the temperature of the printed object 101) is close to the target temperature through feedback control.

[0163] The control of the auxiliary melting device 13 specifically involves, for example, controlling the electrical power supplied to the heat-generating elements (e.g., heating wires or induction coils) via a driver (not shown). More specifically, the voltage, current, and / or frequency (in the case of AC) can be controlled according to the type of heat-generating elements. It should be noted that the second temperature control unit 43 can also be conceptually designed to include a driver. Furthermore, the control of the auxiliary melting device 13 can also be other than the aforementioned control methods. For example, in a configuration that supplies a heat medium to the second heating roller 17B, the flow rate of the heat medium can also be controlled.

[0164] (UV Control Department)

[0165] The UV control unit 45 controls the melting device 11, for example, in a way that maintains the intensity of the UV irradiated onto the printed object 101 at a target value while the working distance (WD) from the melting device 11 to the printed object 101 is constant.

[0166] The target intensity value is substantially constant during the operation of the printing apparatus 1. Alternatively, the target value can be a constant value set by the manufacturer of the printing apparatus 1, a value set by the user, or a value set by the UV control unit 45 based on specified information. The specified information may include, for example, ink-related information input by the manufacturer or user (e.g., information that can determine the Tg of a specified polymer), and / or the temperature of the area in the printed material 101 assuming no UV irradiation of a predetermined area. The temperature assuming no UV irradiation may be a value input by the manufacturer or user, or a value calculated by the UV control unit 45 based on the specified information. The specified information may include, for example, the target temperature values ​​(or heating amounts in other views) of the elements used for heating (9(17A), 21(33), and / or 13(17B)) and the relative positions (distances) of these elements to the melting device 11.

[0167] The UV control unit 45 performs, for example, open-loop control of the UV intensity without feedback. Additionally, the UV control unit 45 controls the power supplied to the UV-generating light source 11a via a driver (not shown). More specifically, the voltage, current, and / or frequency (in the case of AC) can be controlled according to the configuration of the light source 11a. The driver can also perform power feedback control. The UV control unit 45 can also be conceptually designed to include a driver.

[0168] (The fixing effect of ink)

[0169] Figure 5 This is a conceptual diagram illustrating the fixing effect of the ink from the printing apparatus 1 onto the printed object 101.

[0170] Figure 5 The up, down, left, and right directions and Figure 1 The directions of up, down, left, and right correspond. In Figure 5 The image shows a cross-section of a portion of the printed material 101. The printed material 101 is conveyed from the left side of the paper to the right side. A magnified cross-section of a portion of the head 21 is shown in the upper left corner of the paper. As the ink 103 is ejected as droplets from the head 21 and adheres to the surface (upper surface) of the printed material 101, it moves along with the printed material 101, changing the ratio and state of its components (glass state, etc.). Figure 5This can be understood as a graph showing the changes in the state of the same droplet (ink 103) over time, or as a graph showing the simultaneous observation of multiple different droplets. It should be noted that in the following description, the same reference numeral (103) is used for ink, even for the ratio of the components of ink 103 and the changes in the state of the components.

[0171] exist Figure 5 In this context, the state of ink 103 (the ratio of components and the state of the components) is conceptualized into five states, from the first state S1 to the fifth state S5.

[0172] The first state S1 is the state of ink 103 held at the beginning 21 (in other words, before ejection). The ink 103 in the first state S1, for example, contains a medium 105 (solvent and / or dispersion medium), a colorant 107, and two or more polymers (109 and 111). The two or more polymers include at least a fixing polymer 109 and a first polymer 111. The first polymer 111 is an example of a polymer having a Tg higher than room temperature and lower than that of the fixing polymer 109. As described above, the ink may contain other components (including polymers). However, for ease of illustration, in... Figure 5 Illustrations of other components are omitted.

[0173] It should be noted that the description of the first polymer 111 below can also be applied to other polymers, provided that no contradiction arises. Furthermore, in the following description, provided no contradiction arises, the term "first polymer 111" can be replaced with "most (or all) of the polymers contained in the ink other than the fixing polymer 109, which have a Tg higher than room temperature and lower than the Tg of the fixing polymer 109." Regarding "most," it is as described above.

[0174] For illustrative purposes, colorant 107 is depicted as particles (or pigments in other viewpoints) dispersed in medium 105. Additionally, fixer polymer 109 exists as particles (in other words, a solid) in the first state S1. Polymers other than fixer polymer 109, as described above, can be solutes or dispersions in the first state S1; they can also be liquids or solids. The first polymer 111 illustrated is depicted as a strip-shaped dispersant polymer. As stated above, the accompanying drawings are schematic and do not actually reflect the diameter and density of particles within ink 103.

[0175] The second state S2 is the state of the ink 103 when it flies from the nozzle 21 toward the printed object 101 (in other words, after it is ejected and before it drips). The second state S2 (the ratio and state of the components) is basically the same as the first state S1.

[0176] The third state S3 is the state of the ink 103 from the time it adheres to the printed material 101 until a certain period of time has elapsed. In this state, the medium 105 gradually evaporates. At this time, the evaporation of the medium 105 is promoted by preheating the ink 103 using the head heater 33. In addition, the evaporation of the medium 105 is promoted by heating the printed material 101 using the drying device 9, and the heat is transferred to the ink 103.

[0177] Furthermore, although not specifically illustrated, polymers other than the fixer polymer 109 that are particulate in the first states S1 and S2 may partially or completely become glassy in the third state S3. Additionally, any one or more of the other polymers may decompose and evaporate under heat. Additives other than the polymers contained in the ink may remain or evaporate.

[0178] The fourth state, S4, is the state of the ink 103 before it is irradiated with UV light by the melting device 11. In this state, the evaporation of the medium 105 develops compared to the third state, S3. For example, the evaporation of the medium 105 can be completed. Through the evaporation of the medium 105, the solute dissolved in the medium 105 or the dispersed matter dispersed in the medium 105 (other than the dispersed matter evaporated as described above) agglomerates and remains. Figure 5 The image shows the aggregated state of colorant 107 and fixer polymer 109.

[0179] Other polymers besides fixer polymer 109 (e.g., first polymer 111) may remain or be decomposed and evaporated. If they remain, they may or may not be in a glassy state. For example, all remaining polymers besides fixer polymer 109 may be in a glassy state. It should be noted that... Figure 5 In order to simplify the illustration, the first polymer 111, whether present or absent, is omitted from the illustration regarding ink 103 in the fourth state S4 and the fifth state S5.

[0180] The fifth state S5 is the state of the ink 103 when the melting device 11 is irradiated with UV light. In this state, the colorant 107 absorbs UV light and generates heat, under the action of this heat, the fixing polymer 109 melts (becomes in a glassy state). Subsequently, although not specifically illustrated, when the UV irradiation ends and the temperature of the ink 103 drops, the fixing polymer 109 solidifies, and the colorant 107 is fixed to the printed material 101. Although not illustrated, if the ink 103 contains other polymers remaining after heating (e.g., the first polymer 111), these other polymers also solidify (or remain in a solid state).

[0181] As described above, the medium 105 can be partially or completely evaporated before the fixer polymer 109 melts. In this case, for example, the possibility of the fixer polymer 109 forming a film in a glassy state and suppressing the evaporation of the medium 105 can be reduced. As a result, the medium 105 can be evaporated efficiently. The amount of medium 105 evaporated before the fixer polymer 109 melts (or, in other views, before heating using UV) can be set, for example, to 30% or more by mass, 50% or more by mass, 70% or more by mass, or all (95% or more by mass or 100% by mass) based on the first state S1.

[0182] Heating the ink 103 by irradiating it with UV light can, for example, rapidly heat the ink 103, causing the fixer polymer 109 to melt. However, heat generation is primarily concentrated in the colorant 107, resulting in localized heating. Consequently, when heating the ink 103 using only UV light, excessive temperature rises occur locally, potentially degrading the quality of the ink 103 and / or the printed material 101. Heating the printed material 101 using the drying device 9 and / or the auxiliary melting device 13 can, for example, mitigate localized heating while shortening the heating time.

[0183] As for the fixing polymer 109, it can be concluded that whether it is a fixing polymer can be determined based on the presence or absence of the aforementioned effects, rather than on its composition and / or components. That is, the fixing polymer 109 can also be defined as one of the two or more polymers contained in the ink 103 that exists in a solid (particulate) state before being heated by the melting device 11 (e.g., a UV irradiation device), is melted (becomes in a glassy state) by the heating action of the melting device 11 (e.g., UV irradiation), and then remains in the ink 103 as a solid component.

[0184] (Target temperature of the head heater)

[0185] The head 21, for example, can have a head heater 33 that maintains the temperature of the ink 103 in the first state S1 at a predetermined target temperature, as described above. Furthermore, the first state S1 (component ratio and component state) can be set to be substantially the same as the state of the ink 103 at room temperature (except for viscosity, etc.). Therefore, for example, the target temperature of the head heater 33 can be set to a temperature lower than the Tg of any or all types of polymers that will not become glassy at room temperature. Conversely, the ink 103 can be configured such that the Tg of any or all types of polymers is higher than the target temperature of the head heater 33. By setting the target temperature and / or Tg as described above, for example, the possibility of molten polymer adhering to the inner surface of the nozzle 21b is reduced.

[0186] Furthermore, the target temperature of the head heater 33 can be as high as possible within a range lower than the Tg of any or all of the aforementioned polymers. Conversely, the ink 103 can be configured such that the Tg of any or all of the aforementioned polymers is as low as possible within a range higher than the target temperature of the head heater 33. By setting the target temperature and / or Tg in this way, for example, the time from when the ink 103 drips onto the printable substrate 101 to when it is fixed onto the printable substrate 101 can be shortened. In addition, for example, the possibility of unintended diffusion of droplets after dripping onto the printable substrate 101 can be reduced (that is, the shape retention can be improved). It should be noted that the inventors have observed through experiments that when the temperature of the ink 103 is increased in advance (for example, set to 45° or higher in advance), the shape retention of the ink 103 is improved.

[0187] Specific examples of the Tg of any or all of the aforementioned polymers and the target temperature of the head heater 33 are given. The Tg of the polymer can be set to 50°C or higher. On the other hand, the target temperature range of the head heater 33 can be set to 40°C or higher and less than 50°C, or 40°C or higher and less than 45°C. In other views, for example, regarding the difference between the target temperature of the head 21 and the Tg of a specific type of polymer (e.g., a dispersant polymer or a scrub-resistant polymer) contained in the ink 103, assuming that the former is lower than the latter, it can be set to 1°C or higher and less than 10°C, or 1°C or higher and less than 5°C.

[0188] In the second state S2, the ink 103 (droplet) flies through the air, causing its temperature to drop. This temperature change is linear with respect to the distance traveled (time elapsed). Furthermore, the amount of temperature drop is relatively small. An example of estimation is shown below. Imagine a 2 pL droplet flying 1 mm in an atmosphere at 25°C with an initial velocity of 10 m / s. In this case, with an initial temperature of 40°C, the droplet temperature drops to 38.0°C. With an initial temperature of 50°C, the droplet temperature drops to 46.6°C. Imagine a 10 pL droplet flying 1 mm in an atmosphere at 25°C with an initial velocity of 10 m / s. In this case, with an initial temperature of 40.0°C, the droplet temperature drops to 39.3°C. With an initial temperature of 50°C, the droplet temperature drops to 48.8°C. When setting the target temperature of the head heater 33 and / or the target temperature of the drying device 9 described below, the temperature difference may or may not be considered.

[0189] (Target temperature of the drying device)

[0190] The drying apparatus 9, as described above, can maintain the temperature of the printed object 101 at the target temperature. The temperature of the printed object 101 can be considered approximately equal to the temperature of the ink 103 in the third state S3. The target temperature of the drying apparatus 9 (in other views, the temperature of the ink 103 in the third state S3; the same applies in this paragraph and subsequent paragraphs) can be lower than the Tg of the fixer polymer 109. Conversely, the ink 103 can be configured such that the Tg of the fixer polymer 109 is higher than the target temperature of the drying apparatus 9. By setting the target temperature and / or Tg in this way, for example as described above, the possibility of the evaporation of the medium 105 being suppressed by the coating of the molten fixer polymer 109 is reduced.

[0191] The target temperature of the drying apparatus 9 is also as high as possible within a range lower than the Tg of the fixer polymer 109. For example, the target temperature of the drying apparatus 9 can be set such that the temperature of the printable material 101 when the ink 103 drips onto the printable material 101 is higher than the temperature of the ink 103. In this case, for example, the effect of promoting the evaporation of the medium 105 is improved. Conversely, the ink 103 can be selected such that the Tg of the fixer polymer 109 is as low as possible within a range higher than the target temperature of the drying apparatus 9. In this case, for example, the melting time of the fixer polymer 109 can be shortened.

[0192] In setting the target temperature of the drying device 9, the time required for the medium 105 to evaporate can also be taken into account.

[0193] Figure 6 This is a graph showing the estimated time required for the evaporation of medium 105. In this graph, the horizontal axis represents the surface temperature T (°C) of the ink droplets 103. The vertical axis represents the time t (s) for the evaporation of ink 103 in medium 105 to be completed.

[0194] In this estimation, droplets of ink 103 were not considered; instead, droplets of water were assumed. Furthermore, droplets with a diameter of approximately 3.8 × 10⁻⁶ were assumed. -10 m 2 The surface area of ​​a hemispherical water droplet is exposed to an atmosphere at 25°C.

[0195] As shown in the figure, when the temperature T becomes higher than the ambient temperature, the time t shortens sharply, and then remains roughly constant just before reaching the boiling point (approximately 70°C). Although not in Figure 6 As shown, when the temperature T is the same as the ambient temperature (25°C), the time t becomes approximately 4000 s. Based on this result, for example, the target temperature of the drying apparatus 9 can be set to 70°C.

[0196] Specific examples are given regarding the Tg of the fixer polymer 109 and the target temperature of the drying device 9 (in other viewpoints, this is the temperature of the ink 103 in the third state S3; the same applies in this paragraph). The Tg of the fixer polymer can be set to 70°C or higher and 120°C or lower. On the other hand, the target temperature of the drying device 9, provided it is lower than the Tg of the fixer polymer 109, can be set to 50°C or higher and less than 120°C, 60°C or higher and less than 120°C, or 70°C or higher and less than 120°C. Furthermore, in other viewpoints, regarding the difference between the Tg of the fixer polymer 109 and the target temperature of the drying device 9, provided the former is higher than the latter, it can be set to 1°C or higher and less than 50°C, 1°C or higher and less than 30°C, or 1°C or higher and less than 10°C. These specific examples can be combined with the specific examples of the Tg of polymers other than the fixer polymer 109 and the target temperature of the head heater 33, provided they do not cause contradictions.

[0197] In this embodiment, the drying device 9 is implemented by the first heating roller 17A. The temperature of the printed material 101 decreases as it moves away from the position of the first heating roller 17A. In such a solution, the aforementioned target temperature can be set, for example, as a target value of the temperature at a predetermined position immediately in front of the position where the ink 103 drips (the position of the ink ejection device 7) from the position of the first heating roller 17A. For example, the predetermined position can be set as the position of the first heating roller 17A or the position immediately in front of the ink ejection device 7. The target temperature value at the predetermined position can be set such that the temperature of the printed material 101 falls within the aforementioned target temperature range over the entire area from the position of the first heating roller 17A to the position immediately in front of the ink ejection device 7.

[0198] The following shows an example of the results of estimating the temperature distribution of the printed material 101.

[0199] The estimation conditions (assumptions) are as follows. Three conditions are envisioned for the temperature of the first heating roller 17A: 50°C, 60°C, and 70°C. The temperature of the second heating roller 17B is set to 70°C. The effect of the melting device 11 is not considered. The temperature of the ambient atmosphere around the printed material 101 is set to 25°C. The conveying speed of the printed material 101 is set to 100 m / min. The printed material 101 is a PET with a thickness of 12 μm.

[0200] Figure 7 This is a graph showing the estimation results. In this graph, the horizontal axis represents the position x (m) in the D1 direction. The vertical axis represents the temperature T (°C) of the printed material 101. Position x1 represents the position of the first heating roller 17A. Position x2 represents the position of the second heating roller 17B. Lines LT50, LT60, and LT70 represent the estimation results when the temperature of the first heating roller 17A is 50°C, 60°C, and 70°C, respectively.

[0201] As shown in the figure, the temperature of the printed material 101 decreases approximately linearly. Therefore, for example, the temperature of the printed material 101 (ink 103) at other devices (7 or 11) can be easily inferred based on the temperature (heating amount in other views) of the drying device 9 (in this embodiment, the first heating roller 17A), the relative position (distance) of the drying device 9 to other devices (e.g., the ink ejection device 7 or the melting device 11), and the transport speed of the printed material 101. It should be noted that distance and transport speed can also be understood as the transport time from the drying device 9 to the other devices.

[0202] In other viewpoints, by setting the values ​​(target values) of the aforementioned parameters (heating amount, distance, and conveying speed, etc.), any temperature can be achieved at any location, thereby obtaining the various effects described above. For example, the temperature of the portion of the printed material 101 that will be opposite the ink ejection device 7 can be set to a temperature higher than the Tg of the first polymer 111 and lower than the Tg of the fixer polymer 109. In the region from immediately behind the drying device 9 (in this embodiment, the first heating roller 17A) to immediately in front of the portion opposite the melting device 11, the temperature of the printed material 101 can be set to a temperature higher than the Tg of the first polymer 111 and lower than the Tg of the fixer polymer 109. Furthermore, evaporation can be completed before the fixer polymer 109 is melted by the melting device 11.

[0203] exist Figure 7 As shown, when the temperature of the first heating roller 17A is set to 60°C or higher (further, to 70°C or higher), the temperature is maintained at approximately 40°C or higher at a downstream distance of 1.5m. That is, a relatively high temperature is maintained over a relatively long distance (or time, in other views). This, for example, reduces the likelihood of a temperature drop in the ink 103 dripping onto the printable material 101, thus ensuring the shape retention of the ink 103. Alternatively, it allows for heating of the ink 103 to promote evaporation.

[0204] (Target temperature of the auxiliary melting device)

[0205] As described above, the auxiliary melting device 13 can maintain the temperature of the printed object 101 at the target temperature. The auxiliary melting device 13 can also raise the temperature of the printed object 101 to a predetermined temperature lower than the Tg of the fixer polymer 109. In cases where the heating of the melting device 11, which occurs in parallel with the heating of the auxiliary melting device 13, has a significant impact on the temperature of the printed object 101, the target temperature may not be set to the temperature of the printed object 101 itself, but rather to the target value of the temperature of a predetermined portion of the auxiliary melting device 13.

[0206] Regarding the target temperature of the auxiliary melting device 13, the description of the target temperature of the drying device 9 can be appropriately referenced. For example, the target temperature of the auxiliary melting device 13 can be set to be lower than the Tg of the fixing polymer 109, or as high as possible within a range lower than the Tg of the fixing polymer 109. As specific values, the range of the target temperature of the auxiliary melting device 13, provided that it is lower than the temperature of the fixing polymer 109, can be set to 50°C or higher but less than 120°C, 60°C or higher but less than 120°C, or 70°C or higher but less than 120°C. In other viewpoints, regarding the difference between the Tg of the fixing polymer 109 and the target temperature of the auxiliary melting device 13, provided that the former is higher than the latter, it can be set to 1°C or higher but less than 50°C, 1°C or higher but less than 30°C, or 1°C or higher but less than 10°C.

[0207] (UV irradiation by a melting device)

[0208] As described above, the temperature of the printed material 101 (or ink 103 in other views) when it reaches the front of the melting device 11, and / or the temperature of the printed material 101 (or ink 103 in other views) after being heated by the auxiliary melting device 13, can be appropriately set. Furthermore, the intensity of the UV irradiated by the melting device 11 and the irradiation time (or irradiation length in the D1 direction in other views) can be appropriately set in a way that makes the fixing polymer 109 have a Tg or higher.

[0209] Below are examples of estimated results for the temperature rise caused by UV irradiation.

[0210] First, the temperature rise of the resin containing carbon black (pigment) as colorant 107 was estimated. The estimation conditions (assumed) are as follows: the particle shape of colorant 107 is set to cubic with a particle size of 70 nm; the density of colorant 107 is set to 2200 kg / m³. 3 The specific heat of colorant 107 is set to 691 J / kgK. It is assumed that 5200 particles of colorant 107 are present in 0.8 μL of resin. The density of the resin is set to 1060 kg / m³. 3 The specific heat of the resin was set to 1340 J / kgK. The UV intensity was set to 352 kW / m. 2 It is assumed that 80% of the heat is converted into heat. It is also assumed that the heat does not escape to the outside of the resin. Two scenarios, 25°C and 50°C, are considered as the initial temperature before UV irradiation.

[0211] Figure 8A This graph shows the temperature change of 0.8 pL of resin under the conditions described above. The horizontal axis represents the UV irradiation time t (μs). The vertical axis represents the temperature T °C. The dashed line represents the case with an initial temperature of 25 °C, and the solid line represents the case with an initial temperature of 50 °C.

[0212] As shown in the figure, the temperature of the resin containing colorant 107 rises to a temperature above the Tg of fixer polymer 109 within a relatively short time. Specifically, for example, the temperature of the resin rises from 50°C to 120°C in about 0.01 seconds.

[0213] Next, the temperature rise of the water containing the aforementioned resin was estimated. The estimation conditions (assumed) are as follows: 1.2 pL of water is mixed with 0.8 pL of the aforementioned resin (containing 5200 colorant 107 particles) to form the ink. The density of the water is set to 1000 kg / m³. 3 The specific heat of water is set to 4180 J / kgK. It is assumed that heat will not escape to the outside of the ink. Two initial temperatures, 25°C and 50°C, are considered as the initial temperatures before UV irradiation.

[0214] Figure 8B This graph shows the temperature change of water (or, in other views, the ink as a whole) under the conditions described above. The horizontal axis represents the UV irradiation time t (μs). The vertical axis represents the temperature T °C. The dashed line represents the case with an initial temperature of 25 °C, and the solid line represents the case with an initial temperature of 50 °C.

[0215] As shown in the figure, the ink temperature rises to a temperature above the Tg of the fixer polymer 109 within a relatively short period of time. Specifically, for example, the ink temperature rises from 50°C to 120°C in approximately 0.05 seconds.

[0216] As described above, the ink temperature can be estimated based on the UV intensity and irradiation time. Conversely, the UV intensity and irradiation time (irradiation length in the D1 direction) can be set to obtain the desired temperature and / or temperature change. The desired temperature change is, for example, an increase from the temperature of the ink 103 after being heated by the drying unit 9 and / or the auxiliary melting unit 13 (e.g., a temperature lower than the Tg of the fixer polymer 109) to a desired temperature (e.g., a temperature higher than the Tg of the fixer polymer 109).

[0217] Furthermore, the above estimation example indicates that, for example, the temperature of ink 103 can be raised to any temperature within a relatively short time (e.g., less than 0.05 s) by UV irradiation.

[0218] In the above estimation example, the time for ink 103 to rise to 120°C is approximately 0.05 s, while the time for the resin containing colorant 107 to rise to 120°C is approximately 0.01 s. This indicates that UV irradiation causes a localized temperature rise. Other viewpoints suggest that the temperature of ink 103 is not only raised using the melting device 11, but also using the drying device 9 and / or the auxiliary melting device 13, thereby mitigating the localized temperature rise.

[0219] (An example of the device's dimensions)

[0220] The various dimensions of the printing apparatus 1, the various dimensions of the various devices within it, and the relative positions (distances) of the devices to each other can be appropriately set. In this embodiment, since the ink 103 is dried and fixed onto the printed object 101 efficiently, the overall length of the printed object 101 (especially the length from the ink ejection device 7 to the recovery roller 3B) is easily shortened. Examples of size ranges are shown below. The ranges shown below are merely examples, and the various dimensions may also be sizes outside the ranges shown below.

[0221] In the conveying direction (D1 direction) of the printed object 101, the total length of the printing apparatus 1 can be set to 1m or more and 5m or less. The distance parallel to the D1 direction from the axis of the supply roller 3A to the axis of the first heating roller 17A can be set to 200mm or more and 600mm or less. The diameter of the first heating roller 17A (and the second heating roller 17B) can be set to 20mm or more and 100mm or less. The distance parallel to the D1 direction from the axis of the first heating roller 17A to the front end of the ink ejection device 7 can be set to 200mm or more and 600mm or less. The length parallel to the D1 direction from the front end to the rear end of the ink ejection device 7 can be set to 300mm or more and 900mm or less. The length parallel to the D1 direction from the rear end of the ink ejection device 7 to the front end of the melting device 11 or the axis of the second heating roller 17B can be set to 200mm or more and 600mm or less. The length of the melting device 11 from its front end to its rear end, parallel to the D1 direction, can be set to 5 mm or more and 30 mm or less. The length from the rear end of the melting device 11 to the axis of the recovery roller 3B, parallel to the D1 direction, can be set to 300 mm or more and 900 mm or less if a cooling device (not shown) for cooling the printed material 101 (ink 103) is provided. These dimensions can be combined with a conveying speed of the printed material 101 of 50 mm / min or more and 300 mm / min or less.

[0222] As described above, in this embodiment, ink 103 comprises a medium 105, a colorant 107, a fixing polymer 109, and one or more polymers other than fixing polymer 109 (e.g., a first polymer 111). Colorant 107 is soluble in or dispersed in medium 105. Fixing polymer 109 has a glass transition temperature (Tg) higher than room temperature and is dispersed in medium 105. One or more polymers other than fixing polymer 109 have a Tg higher than room temperature and are soluble in or dispersed in medium 105. The Tg of fixing polymer 109 is higher than the Tg of at least 80% by mass of all polymers in ink 103 other than fixing polymer 109 that have a Tg higher than room temperature.

[0223] In this case, the Tg of the fixer polymer 109 can be said to be set relatively high. When the Tg of the fixer polymer 109 is low, for example, when a film is formed from the molten fixer polymer 109, the evaporation of the medium 105 may be hindered by the film. However, the Tg of the fixer polymer 109 is high, thereby reducing the possibility that the evaporation of the medium 105 will be hindered by the film. As a result, for example, the drying time of the ink 103 and the time required for fixing can be shortened.

[0224] The Tg of the fixer polymer 109 can also be higher than the Tg of all the polymers contained in the ink 103.

[0225] In this case, for example, the possibility that the evaporation of medium 105 is hindered by the coating of fixer polymer 109 is reduced, thus enhancing the aforementioned effect.

[0226] Medium 105 may contain water and organic solvents.

[0227] In this case, for example, the aforementioned effect of facilitating the evaporation of the medium 105 is enhanced by increasing the Tg of the fixer polymer, which is typically more difficult to evaporate than organic solvents. Furthermore, the drying rate of the medium 105 before spraying and / or after spraying can be adjusted by using organic solvents. As a result, the evaporation of the medium 105 is facilitated, for example, during the desired period.

[0228] The difference between the Tg of the fixer polymer 109 and the Tg of more than 80% by mass of the polymers in the ink 103 other than the fixer polymer 109 that have a Tg higher than room temperature (a Tg lower than the Tg of the fixer polymer 109) can be set to be above 40°C and below 60°C.

[0229] When the Tg difference is small, the fixing polymer 109 is more likely to melt during the evaporation of the medium 105, increasing the likelihood of hindering the evaporation of the medium 105. Consequently, the evaporation time required for the medium 105 becomes longer. Conversely, when the Tg difference is large (when the Tg of the fixing polymer is too high), the time required for the temperature of the fixing polymer 109 to rise to its Tg becomes longer, and the time required for the molten fixing polymer 109 to cool and solidify also becomes longer. In other words, the drying and fixing time becomes longer. However, if the Tg difference is within the range described above, the likelihood of such adverse conditions occurring can be reduced.

[0230] In ink 103, at least 80% by mass of the polymers comprising all polymers other than the fixer polymer 109, having a Tg higher than that at room temperature, and having a Tg lower than that of the fixer polymer 109, may comprise a dispersant polymer. Alternatively, the aforementioned 80% by mass of polymers may be comprised of a dispersant polymer.

[0231] In this case, for example, if the dispersant polymer is dispersed in the medium 105 before the evaporation of the medium 105 is complete, it is difficult to form a film. Therefore, for example, even if the temperature of the ink 103 is raised to a temperature higher than the Tg of the dispersant polymer, the likelihood of the film hindering the evaporation of the medium 105 is lower compared to a scheme where the temperature of the ink 103 is raised to a temperature higher than the Tg of the fixer polymer. As a result, for example, the effect of making the temperature of the ink 103 relatively high before the film of the fixer polymer 109 is formed is improved, thereby improving the efficiency of the evaporation of the medium 105.

[0232] The printing apparatus 1 may include an ink ejection device 7, a drying device 9, and a melting device 11. The ink ejection device 7 allows the ink 103 to adhere to the workpiece 101. The drying device 9 can promote the evaporation of the medium 105 by heating the workpiece 101. The melting device 11 can melt the fixer polymer 109 by heating the ink 103 adhered to the workpiece 101, thereby fixing the ink 103 (colorant 107) onto the workpiece 101.

[0233] Therefore, for example, the evaporation of the medium 105 and the melting of the fixer polymer 109 can be performed using separate devices. As a result, for example, the required fixing speed of the ink 103 can be increased, the fixing efficiency of the ink 103 can be improved, and / or the quality of the ink 103 can be enhanced. Specifically, for example, the drying device 9 heats the printed material 101, thus pre-raising the temperature of the printed material 101 before the ink 103 drips. Thus, the drying device 9 can immediately raise the temperature of the ink 103 after it drips and begin the evaporation of the medium 105. Additionally, for example, the melting device 11 heats the ink, thus heating the fixer polymer 109 before heat escapes to the printed material 101. As a result, thermal efficiency is improved. Furthermore, for example, not only is the ink 103 heated by the melting device 11, but the ink 103 is also heated via the printed material 101 by the drying device 9, thus reducing the possibility that the quality of the ink 103 and / or the printed material 101 will deteriorate due to localized overheating. For example, the likelihood of wrinkles and / or deformation occurring on the printed material 101 due to localized heating is reduced. It should be noted that the inventors' insight gained through experimentation is that localized heating can indeed cause wrinkles and / or deformation.

[0234] The melting device 11 can be located downstream of the drying device 9 in the conveying direction of the printed material 101. Alternatively, the melting device 11 can melt the fixer polymer 109 after the drying device 9 has evaporated the medium 105.

[0235] In this case, for example, the melting of the fixing polymer 109 by the melting device 11 begins after at least a portion of the medium 105 has evaporated. As a result, the likelihood of the evaporation of the medium 105 being hindered by the film formed by the molten fixing polymer 109 is reduced. Consequently, the ink 103 can be dried and fixed in a short time.

[0236] The amount of heat applied to the printed material 101 by the drying device 9 (target temperature in other views), the relative position of the drying device 9 and the melting device 11 (distance in other views), and the conveying speed of the printed material 101 are determined in such a way that the evaporation of the medium 105 carried out by the drying device 9 is completed before the melting of the fixer polymer 109 carried out by the melting device 11 begins.

[0237] In this case, for example, the effect of reducing the likelihood that the evaporation of the medium 105 will be hindered by the coating of the fixer polymer 109 is improved. Furthermore, for example, the likelihood of bubbles forming within the fixer polymer 109 due to the evaporation of the medium 105 is also reduced, thus improving the quality of the fixed ink 103. Specifically, for example, the decrease in gloss caused by bubbles is reduced.

[0238] The printing apparatus 1 may have an auxiliary melting device 13. The auxiliary melting device 13 may be located on the side opposite to the melting device 11 relative to the printable 101, and heats the printable 101 from the back side of the surface on which the ink 103 is attached to assist in the melting of the fixer polymer 109.

[0239] In this case, for example, the ink on the surface of the printable 101 can be heated using the melting device 11 (e.g., by UV irradiation) while the back side of the printable 101 is heated using the auxiliary melting device 13. As a result, the printable 101 can be heated in a short time, for example. In addition, for example, compared to the method of melting the fixer polymer 109 by UV irradiation alone (which may be included in the technology of the present invention), localized excessive heating within the ink 103 is suppressed, and the possibility of degradation of the quality of the ink 103 and / or the printable 101 is reduced.

[0240] The auxiliary melting device 13 may have a heating surface (outer peripheral surface of the second heating roller 17B) that contacts the back side of the printed material 101 while being controlled to maintain a predetermined temperature. In other words, the auxiliary melting device 13 can heat the printed material 101 in a way that makes the temperature of the printed material 101 reach a predetermined temperature. The melting device 11 can heat the ink adhering to the printed material 101 to a temperature higher than the predetermined temperature.

[0241] In this case, for example, by using the auxiliary melting device 13 to maintain the temperature of the printed object 101 at a predetermined temperature, the aforementioned effect of reducing the possibility of localized excessive heating can be easily achieved. Furthermore, even if the temperature of the atmosphere surrounding the printed object 101 fluctuates, the auxiliary melting device 13 adjusts the heating amount accordingly, thus eliminating the need for control of the melting device 11 (e.g., adjustment of UV intensity or irradiation time). That is, the control of the melting device 11 is simplified.

[0242] The drying device 9 can make the first part 17a and the second part 17b of the heated printed material 101 alternately and repeatedly contact the printed material 101.

[0243] In this case, for example, compared to a solution where the heater is a plate-shaped element that slides relative to the printed material 101 (continuously in contact with the printed material 101) (which may also be included in the technology of this invention), the temperature of the first portion 17a or the second portion 17b, which decreases due to contact with the printed material 101, can rise during periods when it is not in contact with the printed material 101. As a result, for example, the heat generated per unit volume of the heating element such as the heating wire can be reduced, and the rate of heating the printed material 101 can be maintained. Furthermore, the burden on the heating element is reduced.

[0244] The drying device 9 can heat the printed material 101 to a temperature lower than the glass transition temperature (Tg) of the fixer polymer 109. The melting device 11 can heat the ink 103 adhering to the printed material 101 to a temperature higher than the Tg of the fixer polymer.

[0245] In this case, for example, the possibility of the fixer polymer 109 melting due to heating by the drying device 9 is low, or even if it melts, the amount is small. On the other hand, the fixer polymer 109 can be reliably melted using the melting device 11. As a result, the effect of reducing the possibility that the evaporation of the medium 105 is hindered by the coating of the fixer polymer 109 is improved.

[0246] The drying device 9 can heat the printed material 101 to a temperature that is above the Tg of more than 80% by mass of the polymers in the ink 103, excluding the fixer polymer 109, which have a Tg higher than room temperature, but lower than the Tg of the fixer polymer 109.

[0247] In this case, for example, the ink 103 can reach a relatively high temperature within a temperature range lower than the Tg of the fixer polymer 109 by passing through the drying device 9. Therefore, for example, the effect of promoting the evaporation of the medium 105 by the drying device 9 as described above is improved.

[0248] The drying device 9 may include a first drying device (in this embodiment, a first heating roller 17A) located upstream of the ink ejection device 7 in the transport direction (D1 direction) of the printed material 101. The temperature of the portion of the printed material 101 that will be opposite the ink ejection device 7 may be determined by the manufacturer, user, and / or control device 15 in such a way that the temperature of the portion of the printed material 101 that will be opposite the ink ejection device 7 is greater than or equal to the Tg of more than 80% by mass of the polymers contained in the ink 103 other than the fixer polymer 109, which have a Tg higher than room temperature, but less than the Tg of the fixer polymer 109.

[0249] In this case, for example, the temperature of the printed object 101 immediately in front of the ink ejection device 7 is lower than the Tg of the fixer polymer 109, thus reducing the likelihood that the temperature of the subsequently dripping ink 103 will reach the Tg of the fixer polymer 109. Furthermore, this easily achieves the effect described above of reducing the likelihood that the coating of the fixer polymer 109 will hinder the evaporation of the medium 105. On the other hand, it can be said that the temperature of the printed object 101 immediately in front of the ink ejection device 7 is relatively high, thus allowing the temperature of the subsequently dripping ink 103 to rise rapidly in a short time, thereby promoting the evaporation of the medium 105.

[0250] The drying device 9 can be located upstream of the melting device 11 in the transport direction of the printed material 101. The temperature of the printed material 101 in the region immediately behind the drying device 9 and immediately in front of the portion opposite the melting device 11 can be determined by the manufacturer, user, and / or control device 15 in such a way that the temperature of the printed material 101 is higher than but lower than the Tg of more than 80% by mass of the polymers in the ink 103 other than the fixer polymer 109, which have a Tg higher than room temperature. The amount of heating by the drying device 9 (target temperature in other views), the relative position of the drying device 9 and the melting device 11 (distance in other views), and the transport speed of the printed material 101 are all determined by the manufacturer, user, and / or control device 15.

[0251] In this case, for example, in the region immediately behind the drying device 9 and immediately in front of the melting device 11, the temperature of the printed material 101 is lower than the Tg of the fixing polymer 109, thus reducing the likelihood of a film of the fixing polymer 109 forming in this region. Furthermore, the likelihood of the evaporation of the medium 105 being hindered by this film is reduced. On the other hand, it can be said that the temperature of the printed material 101 is relatively high in the aforementioned region, thus enhancing the effect of promoting the evaporation of the medium 105.

[0252] The melting device 11 can heat the ink 103 by irradiating it with UV light onto the ink 103 attached to the printed material 101.

[0253] In this case, the temperature of the colorant 107 is raised by UV irradiation, which in turn heats the fixer polymer 109. Therefore, for example, the fixer polymer 109 can be heated before heat escapes to the printed material 101, thus improving thermal efficiency. In addition, for example, in the heating using UV irradiation, the ink 103 is locally heated, thus effectively reducing localized heating by the drying device 9.

[0254] <Second Implementation Method>

[0255] Figure 9 This is a side view showing the structure of the printing apparatus 201 according to the second embodiment, and is different from that of the first embodiment. Figure 1 correspond.

[0256] In the printing apparatus 201, the melting device 11 is located downstream of the second heating roller 17B in the conveying direction of the printed object 101. In other words, the printing apparatus 201 does not have an auxiliary melting device 13 that is opposite the melting device 11 across the printed object 101. The second heating roller 17B, together with the first heating roller 17A, constitutes a drying device 209 located upstream of the melting device 11. That is, the drying device 209 can have a first drying device composed of the first heating roller 17A and a second drying device composed of the second heating roller 17B.

[0257] Regarding the control and target temperature of the first heating roller 17A (first drying device), as long as there is no contradiction, the description of the control and target temperature of the first heating roller 17A (drying device 9) in the first embodiment can be referenced. In this case, the term "drying device 9" can also be replaced with the term "drying device 209" or the term "first drying device" as long as there is no contradiction.

[0258] Regarding the control and target temperature of the second heating roller 17B (second drying device), the description of the control and target temperature of the first heating roller 17A (drying device 9) in the first embodiment can be referenced, provided there is no contradiction. In this case, the terminology for drying device 9 or first heating roller 17A can be replaced with the terminology for the second drying device or second heating roller 17B, provided there is no contradiction. And / or the description of the control and target temperature of the second heating roller 17B (auxiliary melting device 13) in the first embodiment can also be referenced. In this case, the terminology for auxiliary melting device 13 can be replaced with the terminology for the second drying device, provided there is no contradiction.

[0259] For example, the amount of heat applied to the printed material 101 by the drying device 209 or the second heating roller 17B (second drying device), the relative position of the drying device 209 or the second heating roller 17B to the melting device 11, and the conveying speed of the printed material 101 can be determined in such a way that the evaporation of the medium 105 carried out by the drying device 209 or the second heating roller 17B is completed before the melting of the fixer polymer 109 carried out by the melting device 11 begins. The amount of heat generated by the drying device 209 or the second drying device, the relative position of the second drying device and the melting device 11, and the conveying speed of the printed material 101 can be determined in a region from immediately behind the drying device 209 (or immediately behind the second drying device in other views) to immediately in front of the portion opposite the melting device 11, such that the temperature of the printed material 101 is above the Tg of the first polymer 111 (or more than 80% by mass of all polymers containing a Tg higher than room temperature in the ink 103 other than the fixer polymer 109) and below the Tg of the fixer polymer 109.

[0260] As described above, in this embodiment, the printing apparatus 1 also includes an ink ejection device 7, a drying device 209, and a melting device 11. The ink ejection device 7 causes ink 103, comprising a medium 105 and a fixing polymer 109, to adhere to the workpiece 101. The drying device 209 promotes the evaporation of the medium 105 by heating the workpiece 101. The melting device 11 heats the ink 103 adhered to the workpiece 101, thereby melting the fixing polymer 109 and fixing the ink 103 (colorant 107) onto the workpiece 101.

[0261] Therefore, for example, it achieves the same effect as the first embodiment. Specifically, for example, the evaporation of the medium 105 and the melting of the fixing polymer 109 can be carried out using separate devices. As a result, for example, it is possible to achieve high-speed fixing of the ink 103, high-efficiency fixing of the ink 103, and / or improved quality of the ink 103, etc.

[0262] As in this embodiment, the drying apparatus 209 may have a first drying device (first heating roller 17A) disposed upstream of the ink ejection device 7 in the conveying direction of the printed material 101, and a second drying device (second heating roller 17B) disposed downstream of the ink ejection device 7. The melting device 11 may be located downstream of the second drying device.

[0263] In this case, for example, by using the first heating roller 17A to preheat the temperature of the printed material 101 before the ink 103 drips, the temperature of the dripped ink 103 can be raised earlier. Furthermore, for example, the dripped ink 103 can be heated using the second heating roller 17B to cause the medium 105 to evaporate earlier. Furthermore, the evaporation of the medium 105 can be easily completed before UV irradiation by the melting device 11.

[0264] It should be noted that, compared to the second embodiment, the second heating roller 17B is more easily used to raise the temperature of the fixer polymer 109 to above its Tg, thereby easily reducing the burden on the melting device 11. Furthermore, for example, due to limitations in the mechanism design, if the distance from the ink ejection device 7 to the axis of the second heating roller 17B is the same in both the first and second embodiments, the first embodiment can easily shorten the overall length of the printing device 1.

[0265] <Third Implementation Method>

[0266] Figure 10 This is a side view showing the structure of the printing apparatus 301 according to the third embodiment, and is different from that of the first embodiment. Figure 1 correspond.

[0267] The printing apparatus 301 has multiple (three in the illustrated example) melting devices 11A, 11B, and 11C. The melting devices 11A, 11B, and 11C are essentially the same as the melting device 11 of the first embodiment, except for specific design details such as size. Hereinafter, A to C will sometimes be omitted without distinguishing between the melting devices 11A to 11C. It should be noted that these three melting devices 11 can also be understood as a single melting device.

[0268] The multiple melting devices 11 are positioned differently in the transport direction of the printed material 101. In the printed material 101, the areas irradiated with UV by the multiple melting devices 11 can be separated from each other in the transport direction, or they can be substantially adjacent to each other without gaps, or they can overlap each other.

[0269] Multiple melting devices 11 are arranged, for example, along a portion of the printed material 101 that is bent convex towards the surface due to the second heating roller 17B. Each melting device 11 irradiates the bent portion of the printed material 101 with UV light in the normal direction of that portion. In other words, the bent portion of the printed material 101 is irradiated with UV light from multiple normal directions. Figure 10 The diagram illustrates an example of irradiating a curved portion of the printed material 101 with UV light from three melting devices 11A, 11B, and 11C. More melting devices 11 can be configured by further increasing the distance between each melting device 11 and the printed material 101. This allows UV light from more melting devices 11 to be directed onto the curved portion of the printed material 101. Thus, by irradiating the convexly curved portion of the printed material 101 with UV light, UV light from more melting devices 11 can be irradiated at a near-perpendicular angle relative to a specific area of ​​the printed material 101. As a result, the energy density of the irradiated UV light can be increased, melting the fixer polymer 109 in a shorter time.

[0270] Unlike the illustrated example, multiple melting devices 11 can be arranged along a straight-lined portion of the printed material 101 and UV irradiate that straight-lined portion. Furthermore, the portion of the printed material 101 that is bent convex to the surface and irradiated with UV can be formed by rollers other than the second heating roller 17B, or by two or more rollers.

[0271] Although not specifically illustrated, the curved portion of the printed material 101 can be irradiated with UV light from multiple normal directions by methods other than multiple melting devices 11. For example, a single melting device 11 can be configured along the curved portion of the printed material 101. Specifically, for example, multiple light sources 11a can be arranged along the curved portion of the printed material 101, and common reflectors, reduced diameter sections, and / or power circuits can be provided among the multiple light sources 11a. The reflectors and / or reduced diameter sections can have a shape along the curved portion of the printed material 101. However, such an arrangement can also be understood as defining the melting device 11 according to each light source 11a, and sharing reflectors, reduced diameter sections, and / or power circuits among the multiple melting devices 11. Alternatively, for example, a melting device 11 with a curved surface light source (also an example of a light source 11a) having multiple LEDs (examples of light sources 11a) arranged along the curved portion of the printed material 101 can be provided.

[0272] The wavelength of UV light, the intensity of UV light, and / or the length of the transport direction of the area of ​​the printed material 101 irradiated by UV light in the multiple melting devices 11 can be the same as each other or different from each other.

[0273] For example, the wavelengths of the UV light emitted by multiple (partial or all) melting devices 11 can be set to be the same. In this case, for example, the length of the area of ​​the printed material 101 irradiated by the UV light in the transport direction can be made longer than the length of the area irradiated by a single melting device 11. As a result, for example, the transport speed of the printed material 101 can be increased, and the irradiation time of the same position of the printed material 101 by the UV light required for the melting of the fixer polymer 109 can be ensured. In other viewpoints, the design freedom of the melting device 11 for ensuring the irradiation distance (time) required for the melting of the fixer polymer 109 is increased.

[0274] Furthermore, for example, the wavelengths of the UV light emitted by multiple (part or all) melting devices 11 can be set to be different from each other. As will be explained later in the example of ink variations, the wavelength of the UV light that increases due to the ink's absorption of UV light (heat generated by UV light) varies depending on the color of the ink 103 (the type of colorant 107). Therefore, for example, in the case where the printing apparatus 1 is a color printer, by setting melting devices 11 for each color to irradiate UV light with wavelengths that increase heat generation, multiple colors of ink 103 can be heated evenly.

[0275] It should be noted that, similar to the melting device that irradiates UV onto the curved portion of the printed material 101, multiple melting devices 11 (or multiple light sources 11a in other viewpoints) that irradiate UV with different wavelengths can also be a structure that shares a reflector, a reduced diameter section, and / or a power supply circuit and can be understood as a single melting device. Alternatively, multiple LEDs (examples of light sources 11a) irradiating UV with different wavelengths can be arranged in a mixed manner to form a surface light source (also an example of light source 11a).

[0276] As described above, in this embodiment, the printing apparatus 301 also includes an ink ejection device 7, a drying device 9, and a melting device 11. Therefore, for example, it achieves the same effects as the first embodiment. Specifically, for example, the evaporation of the medium 105 and the melting of the fixing agent polymer 109 can be performed using separate devices. As a result, for example, it is possible to achieve high-speed fixing of the ink 103, high-efficiency fixing of the ink 103, and / or improved quality of the ink 103, etc.

[0277] The printing apparatus 301 may have a conveying device 5 that conveys the printable 101 while bending at least a portion of the printable 101 in a manner that convexes the surface to which the ink 103 is adhered. One or more melting devices 11 may irradiate the portion of the printable 101 bent by the conveying device 5 (more specifically, the second heating roller 17B) with UV light.

[0278] In this case, for example, the outer peripheral side is wider than the inner peripheral side, thus widening the area where more than one melting device 11 can be arranged relative to the UV-irradiated area of ​​the printed material 101. As a result, for example, the energy density can be increased by irradiating UV from multiple normal directions relative to the relatively narrow area of ​​the printed material 101, and the temperature of the ink 103 can be raised in a short time. In addition, for example, the length of the UV-irradiated area can be ensured in directions other than the D1 direction, thus facilitating the shortening of the printing device 1.

[0279] The printing apparatus 301 may have multiple light sources 11a that irradiate UV light of different wavelengths, constituting one or more melting devices 11.

[0280] In this case, for example, as described above, when the printing apparatus 1 is a color printer, by setting the light source 11a of UV with a wavelength that generates more heat for each color, it is possible to heat the inks 103 of multiple colors equally. As a result, for example, the possibility of overheating or underheating in a particular color of ink 103 is reduced. Consequently, the quality of the ink 103 and / or the printed matter 101 is improved. From another perspective, the function of melting the fixer polymer 109 is less dependent on the color of the ink 103, thus increasing its versatility for various printing apparatuses, including monochrome and color printers.

[0281] <Fourth Implementation Method>

[0282] Figure 11 This is a side view showing the structure of the printing apparatus 401 according to the fourth embodiment, and is different from that of the first embodiment. Figure 1 correspond.

[0283] The drying apparatus 409 of the printing apparatus 401, like the drying apparatus 209 of the second embodiment, has a first drying apparatus (first heating roller 17A) located upstream of the ink ejection apparatus 7 and a second drying apparatus 410 located between the ink ejection apparatus 7 and the melting apparatus 11. However, the second drying apparatus 410 has a different structure than the second drying apparatus (second heating roller 17B) of the second embodiment.

[0284] Specifically, the second drying apparatus 410 can be configured as a hot air dryer that blows hot air toward the printed object 101. In the illustrated example, the second drying apparatus 410 has a surface dryer 455A that blows hot air onto the surface of the printed object 101 and a back dryer 455B that blows hot air onto the back of the printed object 101 (hereinafter, both are sometimes referred to simply as dryer 455 without distinction). It should be noted that the second drying apparatus 410 may also have only one of the surface dryer 455A and the back dryer 455B.

[0285] The dryer 455, though not specifically illustrated, includes a heat source and a blower supplying surrounding gas to the heat source. The heat source may be the same as that illustrated in the first heating roller 17A (heating wire, induction coil, or flow path for the heating medium). The blower may be a fan and a motor that rotates the fan. The dryer 455 may also have a duct that directs the gas supplied by the fan to the printed material 101. The duct may also be used to direct gas from a heat source to both the surface and the back of the printed material 101. The gas supplied to the printed material 101 is, for example, air.

[0286] Regarding the control or target temperature of the drying device 409 or the second drying device 410, as long as there is no contradiction, the description of the drying device 9 (first heating roller 17A) in the first embodiment and / or the second drying device (second heating roller 17B) in the second embodiment can be cited.

[0287] For example, the amount of heat applied to the printed material 101 by the drying device 409 or the second drying device 410, the relative position of the drying device 409 or the second drying device 410 to the melting device 11, and the conveying speed of the printed material 101 can be determined in such a way that the evaporation of the medium 105 carried out by the drying device 409 or the second drying device 410 is completed before the melting of the fixing polymer 109 carried out by the melting device 11 begins. The amount of heat applied by the drying device 409 or the second drying device 410, the relative position of the second drying device 410 and the melting device 11, and the conveying speed of the printed material 101 are determined in such a way that the temperature of the printed material 101 is above the Tg of the first polymer 111 (or more than 80% by mass of all polymers containing a Tg higher than room temperature in the ink 103 other than the fixer polymer 109) and below the Tg of the fixer polymer 109.

[0288] Furthermore, for example, the control of the second drying device 410, like other drying devices, can be either open-loop control or feedback control. In the latter case, the temperature sensor that detects the temperature of the printed object 101 can detect the temperature of the printed object 101 itself, the ambient air temperature near the printed object 101, or the temperature of a suitable location within the second drying device 410. However, in the second drying device 410, which is composed of a hot air drying mechanism, the temperature sensor can also detect the temperature of the gas supplied to the printed object 101.

[0289] Additionally, for example, the control of the second drying unit 410, like that of other drying units, can be configured as the control of the electricity of the heat source. However, in the second drying unit 410, which is composed of a hot air drying mechanism, the air supply volume can also be controlled.

[0290] As described above, in this embodiment, the printing apparatus 401 also includes an ink ejection device 7, a drying device 409, and a melting device 11. Therefore, for example, it achieves the same effects as the first embodiment. Specifically, for example, the evaporation of the medium 105 and the melting of the fixing agent polymer 109 can be performed using separate devices. As a result, for example, it is possible to achieve high-speed fixing of the ink 103, high-efficiency fixing of the ink 103, and / or improved quality of the ink 103, etc.

[0291] The drying apparatus 409 (second drying apparatus 410) can be configured as a hot air dryer that delivers the gas to be heated. In this case, for example, the structure of the second drying apparatus is simpler compared to the second embodiment where the second drying apparatus is configured with the second heating roller 17B. It should be noted that, compared to this embodiment, the second embodiment has higher energy efficiency, for example, because heat is less likely to escape to the surrounding area of ​​the printed material 101.

[0292] (Modified examples of ink compositions)

[0293] For the ink composition of the modified examples described below, it is envisioned that it comprises inks 103 of different colors, and that the inks 103 of different colors are irradiated with UV light of the same wavelength (hereinafter sometimes referred to as "specific wavelength"). That is, it is envisioned that the ink composition of the modified examples is suitable for color printers in which the wavelengths of UV irradiated by more than one melting device 11 (or more than one light source 11a in other views) are the same. However, the ink composition of the modified examples can also be suitable for color printers capable of irradiating UV light of different wavelengths.

[0294] Figure 12A This is a schematic diagram illustrating an example of the light absorption characteristics of inks 103 of different colors. The ink 103 in this diagram is, for example, the ink 103 of the embodiment, not the ink 103 of the variant.

[0295] In this graph, the horizontal axis represents wavelength λ (nm). The vertical axis represents absorbance Abs (dimensionless). The range RU represents the wavelength range of UV light. The range RV represents the wavelength range of visible light. The range RI represents the wavelength range of infrared light. The line LY represents the characteristics of yellow ink 103. The line LM represents the characteristics of magenta ink 103. The line LC represents the characteristics of cyan ink 103. The line LK represents the characteristics of black ink 103. The length of the optical path is the same for all four colors.

[0296] Absorbance is, for example, the logarithm of the incident light intensity divided by the emitted light intensity, with a floor of 10. Absorbance can include or exclude the effects of reflection and scattering. For convenience, the effects of reflection and scattering on absorbance are ignored in the following explanation.

[0297] As shown in the figure, the absorbance of ink 103 varies with the wavelength of light. In other words, the heat generated by ink 103 when irradiated with light (e.g., UV) varies with the wavelength of light. Furthermore, the pattern of this variation varies depending on the color of ink 103. The difference in color of ink 103 can be attributed, in other view, to differences in the material and / or content (mass %) of colorant 107. Therefore, the heat generated when irradiated with UV of the same wavelength differs among inks 103 with varying materials and / or contents of colorant 107. In the illustrated example, regarding the absorbance of UV at a specific wavelength λ1, black has the highest absorbance, followed by cyan, while yellow and magenta are both lower. As a result, there is a possibility that black may be overheated, or conversely, yellow and magenta may be underheated.

[0298] Therefore, a UV absorber other than colorant 107 can be added to at least one ink 103 of the ink composition in such a way that the heat generated by UV (or UV of a specified wavelength in other views) from the melting device 11 is made equal among the various types of inks 103 with different colors. For example, the content of UV absorber other than colorant 107 can be made different in at least two of the various types of inks 103 (one ink 103 may also be free of UV absorber). With such a structure, by adjusting the content of UV absorber, the heat generated by UV from the melting device 11 can be made closer among the various types of inks 103.

[0299] Furthermore, among at least two types of inks 103, one ink 103 may have a lower UV absorption rate from the melting device 11 compared to the other ink 103 containing colorant 107. Additionally, one ink 103 may have a higher UV absorber content compared to the other ink 103. In this case, the other ink 103 may not contain any UV absorber. The specific wavelength λ1 used for comparing UV absorption rates can be set as the center wavelength of the UV wavelength region radiated by the melting device 11. The magnitude of the absorption rates of colorant 107 can be set as the magnitude of the molecular absorptivity (molar absorptivity) of colorant 107. Furthermore, the magnitude of the absorption rates of colorant 107 can be set as the magnitude of the absorbance of solutions of equal concentration obtained by dispersing colorant 107 in a solvent (e.g., water). The molecular absorption coefficient is an inherent value depending on the colorant 107, and the concentration of the colorant 107 in the ink 103 does not change significantly. Therefore, with such a structure, the heat generated by the UV from the melting device 11 can be made more similar among the various types of inks 103.

[0300] Furthermore, among the various types of inks 103, the ink 103 with the lower absorption rate of UV from the melting device 11 due to the colorant can have a higher UV absorber content. In other words, when considering two inks 103, one ink 103 may have a lower absorption rate of UV from the melting device 11 due to the colorant 107 compared to the other ink 103. Additionally, one ink 103 may have a higher UV absorber content compared to the other ink 103. In this case, the other ink 103 may be completely free of UV absorbers. The specific wavelength λ1 used for comparing absorption rates can be set to the center wavelength of the UV wavelength region radiated by the melting device 11. The absorption rate can be, for example, set as absorbance or a value obtained by dividing absorbance by the length of the sample (ink) into which UV is incident (absorption coefficient). "The UV absorption rate of ink 103 generated by colorant 107" can be, for example, defined as the UV absorption rate of a sample containing colorant 107 at the same content as the colorant 107 in ink 103, and the remaining portion (e.g., medium 105) substantially not absorbing UV. Alternatively, "the UV absorption rate of ink 103 generated by colorant 107" can be defined as the UV absorption rate of ink 103 obtained by replacing the UV absorber with the same mass of medium 105 in a modified ink 103. The absorption rate can be determined using a known spectrophotometer. With such a structure, the heat generated by UV from the melting device 11 can be made more similar among the various types of ink 103.

[0301] Figure 12B This is a schematic diagram showing an ink composition containing ink 103 with added UV absorber as described above.

[0302] For ease of illustration, only the medium 105, colorant 107, and UV absorber 113 in the composition of ink 103 are shown here; the diagram of fixer polymer 109, etc., is omitted. In the diagram, K, C, Y, and M correspond to black, cyan, yellow, and magenta, respectively.

[0303] The illustrated example envisions using Figure 12A The UV light has a specific wavelength λ1. Furthermore, the black ink 103, which generates the most heat at the specific wavelength λ1, does not contain UV absorber 113. On the other hand, the cyan ink 103 contains UV absorber 113. Additionally, the yellow and magenta inks 103, which generate the least heat at the specific wavelength λ1, contain more UV absorber 113 than the cyan ink 103.

[0304] Figure 13AThis is a schematic diagram illustrating an example of the light absorption characteristics of UV absorber 113. The horizontal and vertical axes of this diagram are aligned with... Figure 12A The horizontal and vertical axes are the same.

[0305] As shown in the figure, UV absorber 113, for example, has a peak where absorbance increases. This peak generally falls within the UV range. That is, UV absorber 113 generates a lot of heat due to UV, while on the other hand, UV absorber 113 has little effect on visible light (visual confirmation of ink 103). For example, the absorbance in the RV range relative to the peak absorbance, or the absorbance at the wavelength (specific wavelength λ1) of UV in the melting device 11, is 10% or less or 5% or less.

[0306] Figure 13B This is a schematic diagram illustrating an example of the light absorption characteristics of ink 103 (ink 103 with added UV absorber 113). The horizontal and vertical axes of this diagram are parallel to... Figure 12A The horizontal and vertical axes are the same. Additionally, lines LY, LM, LC, and LK are... Figure 12A Similarly, it corresponds to the four colors.

[0307] In this diagram, as shown in the reference Figure 12B As explained, by adding... Figure 13A The UV absorber 113 exhibits the following characteristics: the absorbance (or absorptivity, in other views) of the UV light at the wavelength (specific wavelength λ1) of the melting device 11 is equal among multiple colors. For example, at the specific wavelength λ1, the difference in absorptivity among all colors is less than 50%, less than 20%, or less than 10% of the highest absorptivity. It should be noted that in the modified ink composition, the difference in absorptivity at the specific wavelength λ1 among at least two colors of ink 103 can be reduced more or less by the addition of the UV absorber 113. That is, it is also possible to reduce the difference in absorptivity among at least two colors of ink 103 by more or less. Figure 13B In an example, the absorption rate at a specific wavelength λ1 of all colors is made equal.

[0308] The color of ink 103 differs before and after the addition of UV absorber 113. The greater the mass percentage of UV absorber 113 in ink 103, the greater the color difference. Therefore, the mass percentage of UV absorber 113 in each ink 103 can be set not only to reduce the difference in UV absorption rate with other inks 103, but also to keep the color difference caused by the addition of UV absorber 113 below a predetermined threshold.

[0309] The aforementioned threshold is, for example, 10 or 5. This is because the color difference that a human can typically perceive is greater than 5. Color difference can be measured, for example, based on the printed color. Color difference can be measured between ink 103 containing UV absorber 113 and ink 103 containing the same components as ink 103 in the same proportions, excluding UV absorber 113. The proportions referred to here are not the percentage by mass of each component in the ink, but rather the mass ratio of the components to each other.

[0310] It should be noted that the inventors of this application have confirmed through experiments that it is possible to make the UV absorption rates of inks 103 of different colors equal while setting the color difference caused by UV absorber 113 to be 10 or less. Specifically, as follows.

[0311] Prepare to have with Figure 12A The inks 103 (without UV absorber 113) are black, cyan, yellow, and magenta, exhibiting approximately equal properties. In this ink 103, for example, at a wavelength of about 350 nm, the absorbance of black is about 0.8, the absorbance of cyan is about 0.4, and the absorbance of yellow and magenta is about 0.2.

[0312] UV absorber 113 was added to the three colors of ink 103 (excluding black, which has the highest absorbance) mentioned above. The amount of UV absorber 113 added was set to be 5% by mass (for convenience, referred to as 5% by mass) relative to the mass of ink 103 before the addition of UV absorber 113. Dipropylene glycol was used as the UV absorber 113. For dipropylene glycol, the absorbance peaks at a wavelength of approximately 350 nm.

[0313] Furthermore, the absorbance of ink 103 after adding UV absorber 113 was measured. At a wavelength of approximately 350 nm, the absorbance of cyan, yellow, and magenta became higher than that of black (specifically, it became approximately 1 or more). That is, it was confirmed that the absorbance of the four colors could be made equal with an addition amount of 5% by mass or less.

[0314] Under the same conditions as described above, ink 103 without UV absorber 113 and ink 103 with UV absorber 113 were prepared, and the color difference between the two was measured. However, the amount of UV absorber 113 added was set to either 2.5% or 5% of the mass of ink 103 before the addition of UV absorber 113. The color difference was measured using ink 103 that had been coated onto coated paper by a doctor blade coater and had been thoroughly dried and fixed. The thickness of ink 103 was considered to affect the measurement based on the color of the coated paper.

[0315] The results showed that, with an addition of 5% by mass, the color difference was less than 10 for any of the cyan, yellow, and magenta colors. Furthermore, with an addition of 2.5% by mass, the color difference for yellow and magenta was less than 5. Therefore, it can be confirmed that the color difference caused by the addition can be set to 10 or less by using an addition amount that results in equal absorbance.

[0316] The structure of UV absorber 113 can be configured to be suitable. For example, UV absorber 113 can be configured as a protective UV absorber used in polymers or colorants, or as a UV absorber used in cosmetics. Examples of such UV absorbers include dihydroxybenzophenone compounds, benzotriazole compounds, hydroxyphenyltriazine compounds, dipropylene glycol compounds, and cyanoacrylate compounds.

[0317] In this variation, ink 103 also includes a medium 105, a colorant 107, a fixer polymer 109, and other polymers (e.g., a first polymer 111). The Tg of fixer polymer 109 is higher than that of more than 80% by mass of all polymers in ink 103 other than fixer polymer 109, which have a Tg higher than room temperature. Therefore, the same effect as in the embodiment is achieved. For example, the possibility that the evaporation of medium 105 is hindered by the coating of the molten fixer polymer 109 is reduced. As a result, for example, the drying and fixing time required for ink 103 can be shortened.

[0318] The ink composition may contain two inks 103 with different colorants 107. At least one of the two inks 103 may contain a UV absorber 113 other than the colorant 107. The content of UV absorber 113 in the two inks 103 may be different.

[0319] In this case, for example, the amount of heat caused by UV is not only dependent on the colorant 107, but also adjusted by the UV absorber 113. As a result, for example, as described above, it becomes easier to make the amount of heat equal among inks 103 of different colors. Alternatively, conversely, it is also possible to increase the difference in the amount of heat among inks 103 of different colors, and to preferentially dry inks of a particular color.

[0320] In the two inks 103, the colorant 107 contained in one ink (e.g., Y or M) may have a lower UV absorption rate at a specific wavelength λ1 compared to the colorant 107 contained in the other ink 103 (e.g., C or K). The ink 103 may also have a higher UV absorber 113 content compared to the other ink.

[0321] And / or, in the two inks 103, one ink 103 (e.g., Y or M) may have a lower absorption rate of UV of a specific wavelength λ1 by colorant 107 compared to the other ink (e.g., C or K), and the content of UV absorber 113 other than colorant 107 may be greater.

[0322] In these cases, for example, when irradiated with UV light of a specified wavelength λ1, the deviation in the amount of heat generated per unit time between the colors of ink 103 is reduced. Furthermore, the likelihood of overheating or insufficient heating in ink 103 of a specific color is reduced. As a result, for example, fixing of ink 103 relative to the printed object 101 can be performed stably, regardless of the content (color scheme) of the image on the printed object 101.

[0323] The color difference between the printed color of ink 103 containing UV absorber 113 and the printed color of ink having the same components as ink 103 in the same proportion except for UV absorber 113 can be set to 10 or less.

[0324] In this case, for example, the decrease in image quality caused by the addition of UV absorber 113 is reduced. As a result, for example, the fixing time required for ink 103 can be shortened while maintaining image quality.

[0325] (Example)

[0326] Hereinafter, a specific manufacturing method of the ink 103 according to the embodiment is illustrated.

[0327] Figure 14 These are diagrams used to illustrate manufacturing examples 1 and 6. Figure 15 These are diagrams used to illustrate manufacturing examples 2-5. Figure 16 These are diagrams used to illustrate manufacturing examples 7-10.

[0328] Manufacturing Example 1 is an example of a method for manufacturing a dispersant polymer (an example of first polymer 111). Manufacturing Examples 2-5 are examples of methods for manufacturing an aqueous dispersion (a dispersion system mainly mediated by water, hereinafter the same) comprising the dispersant polymer manufactured in Manufacturing Example 1 and a pigment as a colorant 107. Manufacturing Examples 2-5 are four manufacturing examples corresponding to the four colors. Manufacturing Example 6 is an example of a method for manufacturing an aqueous dispersion containing a fixing polymer 109. Manufacturing Examples 7-10 are examples of methods for manufacturing an ink 103 comprising the four-color aqueous dispersions manufactured in Manufacturing Examples 2-5 and the aqueous dispersion of the fixing polymer 109 manufactured in Manufacturing Example 6. It should be noted that, unless otherwise specified, the "parts" attached to the numerical values ​​below refers to "parts by mass".

[0329] (Manufacturing Example 1: Synthesis of Dispersant Polymer)

[0330] Will Figure 14 The various monomers shown were mixed to prepare 115 parts of monomer mixture. It should be noted that the details of the monomers are as follows.

[0331] Styrene: Manufactured by Wako Pure Chemical Industries, Ltd.

[0332] Butyl acrylate: manufactured by Wako Pure Chemical Industries, Ltd.

[0333] Methacrylic acid: manufactured by Wako Pure Chemical Industries, Ltd.

[0334] Methoxylated polyethylene glycol methacrylate: "BLEMMER PME-200" (Nippon Oil Co., Ltd.)

[0335] 10% (11.5 parts) of the monomer mixture, 18 parts of methyl ethyl ketone (MEK), and 0.03 parts of 2-mercaptoethanol (2-mercaptoethanol) as a chain transfer agent were added to the reaction vessel and mixed, followed by thorough nitrogen purging. Meanwhile, the remaining 90% (103.5 parts) of the monomer mixture, 0.27 parts of the chain transfer agent, 42 parts of MEK, and 3 parts of 2,2-azobis(2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd.) as a polymerization initiator were added to a dropping funnel. Then, under a nitrogen atmosphere, the mixture in the reaction vessel was stirred while the temperature was raised to 75°C, and the mixture in the dropping funnel was added dropwise into the reaction vessel over a period of three hours.

[0336] After two hours at 75°C following the completion of the dropwise addition, a solution obtained by dissolving 3 parts of the polymerization initiator in 5 parts of methyl ethyl ketone is added to the reaction vessel. The mixture is then cured at 75°C for two hours, followed by curing at 80°C for two hours. Finally, 50 parts of methyl ethyl ketone are added to the reaction vessel.

[0337] Thus, a solution of the dispersant polymer is obtained. The weight-average molecular weight of the dispersant polymer is approximately 50,000. The Tg of the dispersant polymer is approximately 60°C. The concentration of the solids component in the solution of the dispersant polymer is approximately 45% by mass.

[0338] (Example 2: Manufacturing of an aqueous dispersion containing black pigment and dispersant polymer)

[0339] 95.2 parts of the dispersant polymer solution obtained in Manufacturing Example 1 were dissolved in 53.9 parts of methyl ethyl ketone. 15.0 parts of 5N sodium hydroxide aqueous solution and 0.5 parts of 25% ammonia were added as neutralizing agents, followed by 341.3 parts of deionized water. Then, 100 parts of CI Pigment Black 7 (PB7, manufactured by Chabot) were added as carbon black pigment to obtain a pigment mixture. The degree of neutralization was approximately 79 mol%.

[0340] The pigment mixture was mixed for one hour at 7000 rpm and 20°C using a disperser blade. The resulting dispersion was then dispersed 15 times at 180 MPa using a microfluidics M-140K high-pressure homogenizer.

[0341] The obtained dispersion was subjected to vacuum treatment at 60°C to remove methyl ethyl ketone, followed by water removal. The dispersion was then centrifuged, and the liquid phase was filtered using a Minisart needle filter (Sartorius, 6 μm pore size, cellulose acetate) to remove coarse particles, yielding an aqueous dispersion containing black pigment and dispersant polymer.

[0342] 100 parts of the obtained aqueous dispersion were mixed with 0.45 parts of epoxy crosslinking agent (trimethylolpropane polyglycidyl ether manufactured by Nagase ChemeteX Co., Ltd., trade name: DENACOL EX321L, epoxy equivalent 130) and 15.23 parts of deionized water, and heated at 70°C for three hours while stirring.

[0343] After cooling the heated aqueous dispersion to room temperature, coarse particles were removed by filtering the liquid layer using a Minisart needle filter (Made by Sartorius, pore size: 5 μm, material: cellulose acetate), yielding an aqueous dispersion containing black pigment and dispersant polymer. The solids concentration was approximately 22% by weight. The average particle size of the dispersant polymer was approximately 100 nm. Figure 15 The composition and physical properties of the obtained aqueous dispersion are shown.

[0344] (Manufacturing Examples 3-5: Manufacturing of aqueous dispersions containing pigments of other colors and dispersant polymers)

[0345] Manufacturing Examples 3-5 are identical to Manufacturing Example 2, except for changes in the type and amount of pigment added, and the amount of DENACOL EX321L added. It should be noted that... Figure 15 The details of the pigments shown are as follows.

[0346] Cyan: CI Pigment Blue 15:3 (manufactured by DIC Corporation)

[0347] Magenta: CI Pigment Red 150 (manufactured by Fuji Pigment Co., Ltd.)

[0348] Yellow: CI Pigment Yellow 74 (manufactured by Dainippon Seika Co., Ltd.)

[0349] (Example 6: Manufacturing of an aqueous dispersion containing a fixer polymer)

[0350] Mix in a 1000mL separable flask Figure 14 Prepare 200 parts of monomer mixtures by mixing each monomer shown. Add 18.5 parts of LATEMUL E118B (manufactured by Kao Corporation, emulsifier, 26% active ingredient), 96 parts of deionized water, and potassium persulfate (manufactured by Wako Pure Chemical Industries, Ltd.) to the monomer mixture and stir using a stirring blade (300 rpm) to obtain a monomer emulsion.

[0351] 4.6 parts of LATEMUL E118B, 186 parts of deionized water, and 0.08 parts of potassium persulfide were added to the reaction vessel, followed by nitrogen purging. Under a nitrogen atmosphere, the reaction vessel was stirred (200 rpm) while being heated to 80°C. The monomer emulsion was added dropwise to the reaction vessel over a period of three hours using a dropping funnel to allow the reaction to proceed, yielding an aqueous dispersion containing fixer polymer 109.

[0352] In the aqueous dispersion containing the fixing auxiliary polymer, the solid content is about 42% by weight, and the average particle size of the fixing polymer 109 is about 100 nm.

[0353] (Manufacturing Example 7: Manufacturing of Black Ink)

[0354] 508.9 g of an aqueous dispersion (22.0 wt% solids) containing black pigment and dispersant polymer obtained in Manufacturing Example 2, 48.3 g of an aqueous dispersion (41.6 wt% solids) containing fixer polymer 109 obtained in Manufacturing Example 6, 44.0 g of diethylene glycol monoisobutyl ether (boiling point 230°C), 286.0 g of propylene glycol (boiling point 188°C), 5.5 g of a silicone surfactant (manufactured by Shin-Etsu Chemical Industry Co., Ltd., polyether-modified silicone, KF-6011, HLB14.5), and 207.3 g of deionized water were mixed. The mixture was filtered using a Minisart needle filter (manufactured by Sartorius, pore size: 5 μm, material: cellulose acetate) to obtain a black aqueous ink. Figure 16 The composition and physical properties of black ink are shown.

[0355] (Manufacturing Examples 8-10: Manufacturing of Inks of Other Colors)

[0356] Manufacturing Examples 8 to 10 are essentially the same as Manufacturing Example 7, except that the aqueous dispersion containing black pigment is replaced with the aqueous dispersion obtained in Manufacturing Examples 3 to 5. Figure 16 The composition and physical properties of cyan, magenta, and yellow inks are shown.

[0357] The technology of the present invention is not limited to the above-described embodiments, and can be implemented in various ways.

[0358] The printing apparatus for the inks applicable to this invention is arbitrary and not limited to the printing apparatus described in the embodiments. For example, the printing apparatus may also be a structure that does not separate a drying apparatus for promoting the evaporation of the medium from a melting apparatus for melting the fixer polymer. Specifically, for example, as an apparatus that combines a drying apparatus and a melting apparatus, a heated roller, a UV irradiation apparatus, and / or a hot air dryer may be provided. In this case, for example, the possibility of early film formation of the molten fixer polymer is reduced, and the efficiency of medium evaporation is also easily improved.

[0359] In other viewpoints, the fixer polymer can be melted, for example, by heated rollers or a hot air dryer, without UV irradiation. The fixer polymer can be melted by heat transferred from the printable surface to the ink, rather than by direct heating of the ink without directly heating the printable surface. The medium can be evaporated by UV irradiation, rather than by heating the medium with heated rollers or a hot air dryer.

[0360] The printed material is not limited to long strips of material, nor is it limited to roller conveying. For example, the printing apparatus may also convey the material using a conveyor belt, placing the printed material on the conveyor belt for transport. In this case, the printed material may be, for example, a sheet of paper, a cut piece of cloth, wood, or tile.

[0361] The printing apparatus is not limited to a printing apparatus having a conveying device that moves the printed material. In other words, the "conveyance direction of the printed material," "upstream in the conveying direction," and "downstream in the conveying direction" can also be abstracted. For example, the printing apparatus can move various devices (drying device, ink ejection device, melting device, and / or auxiliary melting device) while the printed material is stationary. Specifically, for example, printing can be performed while a robot moves the ink ejection device along the surface of the printed material. Furthermore, the medium can be evaporated using a hot air dryer, either equipped with it or conveyed by the robot, before the ink ejection device approaches the printed material or after the ink ejection device retracts. The fixing polymer can also be melted by using a robot to bring the melting device close to the surface of the printed material after the ink ejection device retracts. In this embodiment, for example, printing can be performed in three dimensions, not only in two dimensions, but also by moving the ink ejection device along the surface of the printed material, which has a three-dimensional shape. In addition, the conveying of the printed material and the movement of various devices can be combined. According to the embodiment, the "conveyance direction of the printed material" can be replaced by the "relative movement direction" between the printed material and the various devices.

[0362] The drying apparatus is not limited to heated rollers or hot air dryers. For example, the drying apparatus may also heat the printed material by irradiating it with infrared rays. Although mentioned in the description of the embodiments, the drying apparatus is not limited to the upstream and downstream side of the ink ejection device in the conveying direction of the printed material, and may also be located at the same position as the ink ejection device. For example, the drying apparatus may have a plate-shaped heater that is opposite the ink ejection device across the printed material and abuts against the back of the printed material. The melting apparatus is not limited to a UV-irradiating melting apparatus. For example, a melting apparatus that directly heats the ink without passing through the printed material may be a hot air blowing melting apparatus, or it may be an infrared-irradiating melting apparatus.

Claims

1. A printing apparatus, wherein, The printing apparatus has: An ink ejection device that allows ink to adhere to the object being printed; A drying device that promotes the evaporation of the medium by heating the printed material; as well as A melting device that fuses the ink to the printed surface by heating the ink adhering to the printed surface, thereby melting the fixer polymer and fixing the ink to the printed surface. The ink comprises: The medium; A colorant that is soluble in or dispersed in the medium; The fixing polymer has a glass transition temperature above 20°C and is dispersed in the medium; and One or more polymers other than the fixer polymer, having a glass transition temperature higher than 20°C, and soluble in or dispersed in the medium. The glass transition temperature of the fixer polymer is higher than that of more than 80% by mass of all polymers in the ink other than the fixer polymer that have a glass transition temperature higher than 20°C. The difference between the glass transition temperature of the fixer polymer and the glass transition temperature of the polymer comprising more than 80% by mass is 40°C and less than 60°C. The drying apparatus heats the printed material to a temperature above the glass transition temperature of more than 80% by mass of the polymer but below the glass transition temperature of the fixer polymer. The melting device heats the ink by irradiating it with ultraviolet light onto the printed material.

2. The printing apparatus according to claim 1, wherein, The glass transition temperature of the fixer polymer is higher than that of all polymers contained in the ink other than the fixer polymer.

3. The printing apparatus according to claim 1, wherein, The medium contains water and organic solvents.

4. The printing apparatus according to claim 1, wherein, The polymer comprises more than 80% by mass of a dispersant polymer.

5. The printing apparatus according to claim 1, wherein, The melting device is located downstream of the drying device in the conveying direction of the printed material.

6. The printing apparatus according to claim 1, wherein, The melting device melts the fixing polymer after the drying device evaporates the medium.

7. The printing apparatus according to any one of claims 1 to 6, wherein, The amount of heat applied to the printed material by the drying device, the relative position of the drying device and the melting device, and the conveying speed of the printed material are determined in such a way that the evaporation of the medium carried out by the drying device is completed before the melting of the fixing polymer carried out by the melting device begins.

8. The printing apparatus according to any one of claims 1 to 6, wherein, The melting device heats the ink adhering to the printed material to a temperature above the glass transition temperature of the fixer polymer.

9. The printing apparatus according to claim 8, wherein, The drying apparatus includes a first drying device located upstream of the ink ejection device in the conveying direction of the printed material. The amount of heat generated by the first drying device, the relative position of the first drying device and the ink ejection device, and the conveying speed of the printed material are determined in such a way that the temperature of the portion of the printed material about to be opposite the ink ejection device is above the glass transition temperature of 80% or more of the polymer but below the glass transition temperature of the fixer polymer.

10. The printing apparatus according to claim 8, wherein, The drying device is located upstream of the melting device in the conveying direction of the printed material. The amount of heat generated by the drying device, the relative position of the drying device and the melting device, and the conveying speed of the printed material are determined in such a way that the temperature of the printed material is above and below the glass transition temperature of 80% or more of the polymer by mass of the fixing polymer in the region immediately behind the drying device to immediately in front of the portion opposite the melting device.

11. A printing method, wherein, The printing method has the following characteristics: The ink ejection step allows the ink to adhere to the printed material; The drying step promotes the evaporation of the medium by heating the printed material; as well as The melting step involves heating the ink adhering to the printed material to melt the fixer polymer, thereby fixing the ink onto the printed material. The ink comprises: The medium; A colorant that is soluble in or dispersed in the medium; The fixing polymer has a glass transition temperature above 20°C and is dispersed in the medium; and One or more polymers other than the fixer polymer, having a glass transition temperature higher than 20°C, and soluble in or dispersed in the medium. The glass transition temperature of the fixer polymer is higher than that of more than 80% by mass of all polymers in the ink other than the fixer polymer that have a glass transition temperature higher than 20°C. The difference between the glass transition temperature of the fixer polymer and the glass transition temperature of the polymer comprising more than 80% by mass is 40°C and less than 60°C. In the drying step, the printed material is heated to a temperature above and below the glass transition temperature of the polymer (at least 80% by mass) and the glass transition temperature of the fixer polymer. In the melting step, the ink adhering to the printed material is heated by irradiating it with ultraviolet light.

12. The printing method according to claim 11, wherein, The melting step involves melting the fixer polymer after the drying step has evaporated the medium.

13. The printing method according to claim 11 or 12, wherein, In the melting step, the ink adhering to the printed material is heated to a temperature above the glass transition temperature of the fixer polymer.

Images