Degassing module, inkjet printer, and degassing method

Abstract

This degassing module comprises: a hollow fiber membrane bundle including a plurality of hollow fiber membranes bundled into a cylindrical shape; and a housing that accommodates the hollow fiber membrane bundle. The space in the housing is divided, using the plurality of hollow fiber membranes as boundaries, into an internal space including a hollow part of each of the plurality of hollow fiber membranes and an external space not including the hollow part of each of the plurality of hollow fiber membranes. The housing has a suction port that is in communication with the internal space, and a liquid supply port and a liquid discharge port that are in communication with the external space. The hollow fiber membrane bundle is formed by winding, into a cylindrical shape, a hollow fiber membrane sheet in which the plurality of hollow fiber membranes are connected in a blind-like manner using a plurality of connecting fibers. The spacing between the plurality of hollow fiber membranes in the hollow fiber membrane sheet is greater than or equal to 0.1 mm.

Description

Degassing module, inkjet printer, and degassing method

[0001] The present disclosure relates to a degassing module for degassing a liquid, an inkjet printer, and a degassing method for degassing a liquid.

[0002] An inkjet printer is a printing machine that ejects atomized ink from an inkjet head and directly prints on a printing medium. In such an inkjet printer, during printing, the dissolved gas in the ink gasifies due to pressure fluctuations inside the ink storage unit, which may cause nozzle clogging. As a result, there is a risk of significantly reducing the print quality. This is particularly noticeable during long-term use and high-speed operation. To solve such problems, it is effective to perform degassing to remove dissolved gas and bubbles from the ink. As a method of degassing the ink, Patent Document 1 discloses attaching a degassing module using a hollow fiber membrane to the ink flow path from the ink storage unit to the inkjet head and continuously degassing the ink.

[0003] The degassing module described in Patent Document 1 is configured such that a hollow fiber membrane bundle formed by bundling a plurality of hollow fiber membranes is housed in a cylindrical body. By reducing the pressure inside the plurality of hollow fiber membranes, the ink passing between the plurality of hollow fiber membranes is degassed, and the degassed ink is discharged from a discharge port formed on the side wall of the cylindrical body.

[0004] International Publication No. 2007 / 063720

[0005] When such inkjet printers are used for extended periods, ink components can precipitate on the surface of multiple hollow fiber membranes, narrowing the gaps between the membranes that serve as ink pathways. This can cause ink to clog the degassing module, increasing the pressure required to supply ink to the inkjet head. The inkjet head has a set pressure value for supplying ink. A pump attached to the ink flow path then pumps ink at this pressure to supply ink to the inkjet head. Therefore, when the pressure required to supply ink to the inkjet head increases, the ink supply by the pump becomes insufficient, resulting in ink ejection failure. This type of ink ejection failure is particularly noticeable when using ceramic ink or pigment ink. Furthermore, this problem is not limited to ink. When degassing various liquids using a degassing module with hollow fiber membranes, liquid components can precipitate on the surface of the multiple hollow fiber membranes, narrowing the gaps between the membranes that serve as liquid pathways. As a result, the degassing module becomes clogged with liquid.

[0006] Therefore, the object of this disclosure is to provide a degassing module, an inkjet printer, and a degassing method that can suppress clogging of the degassing module.

[0007] [1] The degassing module according to the present disclosure comprises a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled in a cylindrical shape, and a housing that houses the hollow fiber membrane bundle, wherein the space inside the housing is divided into an internal space that includes the hollow parts of each of the plurality of hollow fiber membranes and an external space that does not include the hollow parts of each of the plurality of hollow fiber membranes, with the plurality of hollow fiber membranes as the boundary, and the housing has a suction port that communicates with the internal space and a liquid supply port and a liquid discharge port that communicate with the external space, and the hollow fiber membrane bundle is a hollow fiber membrane sheet in which a plurality of hollow fiber membranes are connected in a curtain-like manner by a plurality of connecting threads and wound in a cylindrical shape, and the spacing between the plurality of hollow fiber membranes in the hollow fiber membrane sheet is 0.1 mm or more.

[0008] In this degassing module, when suction is applied to the suction port and liquid is supplied to the liquid supply port, the liquid is degassed as it passes between multiple hollow fiber membranes. The hollow fiber membrane bundle is made up of hollow fiber membrane sheets, each consisting of multiple hollow fiber membranes connected in a curtain-like fashion by multiple connecting threads, wound into a cylindrical shape. The spacing between the multiple hollow fiber membranes in the hollow fiber membrane sheet is 0.1 mm or more. Therefore, even if liquid components precipitate on the surface of the multiple hollow fiber membranes, it is possible to prevent the gaps between the multiple hollow fiber membranes from narrowing to the point where the liquid clogs the degassing module. This prevents the degassing module from becoming clogged.

[0009] [2] In the degassing module described in [1], the spacing between the multiple connecting threads in the hollow fiber membrane sheet may be 8 mm or less. In this degassing module, the spacing between the multiple connecting threads in the hollow fiber membrane sheet is 8 mm or less. Therefore, when the multiple hollow fiber membranes swell, the multiple hollow fiber membranes are more likely to undulate or spread out. As a result, the gaps between the multiple hollow fiber membranes widen, which further suppresses clogging of the degassing module.

[0010] [3] In the degassing module described in [1] or [2], the hollow fiber membrane packing ratio, which is the ratio of the sum of the apparent cross-sectional areas of the hollow fiber membranes to the apparent cross-sectional area of ​​the hollow fiber membrane bundle, may be 90% or less. In this degassing module, the hollow fiber membrane packing ratio is 90% or less. Therefore, even if liquid components precipitate on the surface of multiple hollow fiber membranes, it is possible to suppress the narrowing of the gaps between the multiple hollow fiber membranes to the point where the degassing module becomes clogged with liquid. This further suppresses clogging of the degassing module.

[0011] [4] In the degassing module described in any of [1] to [3], the separation distance between the housing and the hollow fiber membrane bundle may be 0.1 mm or more. In this degassing module, the separation distance between the housing and the hollow fiber membrane bundle is 0.1 mm or more. Therefore, when multiple hollow fiber membranes swell, it is possible to suppress the multiple hollow fiber membranes from being pressed against the housing. This further suppresses clogging of the degassing module.

[0012] [5] In the degassing module described in any of [1] to [4], an inner support may be further provided, which is positioned in the hollow portion of the hollow fiber membrane bundle and supports the hollow fiber membrane bundle from the inner circumferential side. In this degassing module, the hollow fiber membrane bundle is supported from the inner circumferential side by the inner support. Therefore, when multiple hollow fiber membranes swell, it is possible to suppress the multiple hollow fiber membranes from entering the hollow portion of the hollow fiber membrane bundle and narrowing or blocking the hollow portion. This makes it possible to suppress an increase in the pressure loss of the liquid flowing through the hollow portion of the hollow fiber membrane bundle.

[0013] [6] In the degassing module described in any of [1] to [5], an outer support may be further provided, which is positioned between the hollow fiber membrane bundle and the housing to support the hollow fiber membrane bundle from the outer periphery. In this degassing module, the hollow fiber membrane bundle is supported from the outer periphery by the outer support. Therefore, when the multiple hollow fiber membranes swell, it is possible to suppress the multiple hollow fiber membranes from being pressed against the housing. This further suppresses clogging of the degassing module.

[0014] [7] A degassing module according to any of [1] to [6], further comprising: a first fixing portion that fixes one end of the hollow fiber membrane bundle, which is a first membrane bundle end, to the housing and seals the hollow portions of each of the plurality of hollow fiber membranes at the first membrane bundle end, thereby opening the hollow portions of the hollow fiber membrane bundle; and a second fixing portion that fixes the other end of the hollow fiber membrane bundle, which is a second membrane bundle end, to the housing and seals the areas within the housing other than the hollow portions of each of the plurality of hollow fiber membranes in a cross section passing through the second membrane bundle end and perpendicular to the direction of extension of the hollow fiber membrane bundle, wherein a suction port is formed on the side of the housing opposite to the first fixing portion relative to the second fixing portion, a liquid supply port is formed between the first fixing portion and the second fixing portion of the housing, and a liquid discharge port may be formed on the side of the housing opposite to the second fixing portion relative to the first fixing portion.

[0015] In this degassing module, the first fixing part fixes the end of the first membrane bundle to the housing, sealing the hollow portions of each of the multiple hollow fiber membranes at the end of the first membrane bundle and leaving the hollow portions of the hollow fiber membrane bundle open. The second fixing part fixes the end of the second membrane bundle to the housing, sealing the areas within the housing other than the hollow portions of each of the multiple hollow fiber membranes in a cross section perpendicular to the direction of extension of the hollow fiber membrane bundle passing through the end of the second membrane bundle. As a result, the first and second fixing parts divide the space within the housing into an internal space that includes the hollow portions of each of the multiple hollow fiber membranes and an external space that does not include the hollow portions of each of the multiple hollow fiber membranes, with the multiple hollow fiber membranes serving as the boundary. A suction port is formed on the side of the housing opposite the first fixing part to the second fixing part, a liquid supply port is formed between the first and second fixing parts of the housing, and a liquid discharge port is formed on the side of the housing opposite the second fixing part to the first fixing part. Therefore, by drawing air through the suction port and supplying liquid to the liquid supply port, the liquid can be degassed, and the degassed liquid can be discharged from the liquid discharge port.

[0016] [8] The degassing module described in [7] may further include an outlet formed on the side of the housing opposite to the first fixing part relative to the second fixing part, for discharging liquid from the internal space. In this degassing module, an outlet for discharging liquid from the internal space is formed on the side of the housing opposite to the first fixing part relative to the second fixing part. Therefore, even if liquid components such as water vapor contained in the gas that has permeated through the multiple hollow fiber membranes liquefy in the internal space, or if liquid permeates through the multiple hollow fiber membranes, this liquid can be discharged from the outlet. This makes it possible to prevent the internal space from becoming clogged with liquid.

[0017] [9] The inkjet printer according to the present disclosure comprises an inkjet head, an ink channel for supplying ink to the inkjet head, and a degassing module according to any one of [1] to [8] attached to the ink channel. In this inkjet printer, since any of the above degassing modules is attached to the ink channel, clogging of the degassing module can be suppressed, thereby suppressing the occurrence of ink ejection failures.

[0018] In the inkjet printer described in

[10] and [9], the suction port of the degassing module may be located at the bottom of the degassing module. In this inkjet printer, the suction port of the degassing module is located at the bottom of the degassing module. Therefore, even if liquid components such as water vapor contained in the gas that has permeated through the multiple hollow fiber membranes liquefy in the internal space, or if liquid permeates through the multiple hollow fiber membranes, this liquid can be discharged from the degassing module through the suction port by gravity. Therefore, it is possible to prevent the internal space of the degassing module from becoming clogged with liquid.

[0019]

[11] The inkjet printer described in

[10] may further include a suction tube connected to a suction port and a discharge device for discharging liquid from the suction tube. In this inkjet printer, the discharge device discharges liquid from the suction tube connected to the suction port. Therefore, even if liquid components such as water vapor contained in gas that has permeated through multiple hollow fiber membranes liquefy in the internal space, or if liquid permeates through multiple hollow fiber membranes, this liquid can be discharged through the suction tube. This makes it possible to prevent the suction device from malfunctioning due to sucking in liquid, for example, when a suction device such as a pump is connected to the suction tube.

[0020] In the inkjet printer described in any of [9] to

[11] , the degassing module further comprises: a first fixing portion that fixes one end of the hollow fiber membrane bundle, which is a first membrane bundle end, to the housing and seals the hollow portions of each of the plurality of hollow fiber membranes at the first membrane bundle end, thereby opening the hollow portions of the hollow fiber membrane bundle; and a second fixing portion that fixes the other end of the hollow fiber membrane bundle, which is a second membrane bundle end, to the housing and seals the areas within the housing other than the hollow portions of each of the plurality of hollow fiber membranes in a cross section passing through the second membrane bundle end and perpendicular to the direction of extension of the hollow fiber membrane bundle, and is located below the first fixing portion, wherein a suction port is formed on the side of the housing opposite to the first fixing portion relative to the second fixing portion, a liquid supply port is formed between the first fixing portion and the second fixing portion of the housing, and a liquid discharge port may be formed on the side of the housing opposite to the second fixing portion relative to the first fixing portion.

[0021] In this inkjet printer, the first fixing part fixes the end of the first film bundle to the housing, sealing the hollow portions of each of the multiple hollow fiber membranes at the end of the first film bundle, while leaving the hollow portions of the hollow fiber membrane bundle open. The second fixing part fixes the end of the second film bundle to the housing, sealing the areas within the housing other than the hollow portions of each of the multiple hollow fiber membranes in a cross section perpendicular to the direction of extension of the hollow fiber membrane bundle passing through the end of the second film bundle. As a result, the first and second fixing parts divide the space within the housing into an internal space containing the hollow portions of each of the multiple hollow fiber membranes and an external space not containing the hollow portions of each of the multiple hollow fiber membranes, with the multiple hollow fiber membranes serving as the boundary. A suction port is formed on the side of the housing opposite the first fixing part to the second fixing part. Therefore, by drawing suction through the suction port, the ink flowing through the ink channel can be degassed. Furthermore, the second fixing part is positioned below the first fixing part, the liquid supply port is formed between the first and second fixing parts of the housing, and the liquid discharge port is formed on the side of the housing opposite the second fixing part to the first fixing part. As a result, the ink supplied from the liquid supply port flows through the external space, sweeping the ink stored in the external space from bottom to top, and is discharged from the liquid discharge port. This prevents the accumulation of ink components at the bottom of the external space.

[0022]

[13] An inkjet printer described in any of [9] to

[12] may further be provided with a heating device for heating the ink channel. In this inkjet printer, the heating device can heat the ink in the ink channel by heating the ink channel. Therefore, even if the ink components solidify in the ink channel due to the ink flow being stopped for a long period of time, the heating device can redissolve the solidified ink components. This can suppress clogging of the inkjet head due to solidified ink components. Furthermore, even if a pump for delivering ink is attached to the ink channel, clogging of the pump due to solidified ink components can be suppressed.

[0023]

[14] The degassing method according to the present disclosure is a degassing method for degassing a liquid using a degassing module described in any of [1] to [8], wherein the suction port of the degassing module is sucked and liquid is supplied to the liquid supply port of the degassing module. In this degassing method, by sucking the suction port of the degassing module and supplying liquid to the liquid supply port of the degassing module, the liquid can be degassed while suppressing clogging of the degassing module.

[0024] According to this disclosure, clogging of the degassing module can be suppressed.

[0025] This is a schematic diagram of the inkjet printer according to the embodiment. This is a schematic cross-sectional view of the degassing module according to the embodiment. Figures 3(a) and 3(b) are schematic diagrams of a part of the hollow fiber membrane bundle shown in Figure 2. This is a cross-sectional view taken along line IV-IV shown in Figure 2. This is a perspective view for explaining the structure of the hollow fiber membrane bundle. This is a plan view showing a part of the hollow fiber membrane sheet. Figures 7(a), 7(b), and 7(c) are cross-sectional views of the hollow fiber membrane bundle. This is an enlarged cross-sectional view of a part of the hollow fiber membrane bundle. This is a schematic cross-sectional view of a modified degassing module. This is a cross-sectional view taken along line X-X shown in Figure 9. This is a schematic cross-sectional view of a modified degassing module. This is a schematic diagram of the inkjet printer according to the modification

[0026] The degassing module, inkjet printer, and degassing method of this embodiment will be described in detail below with reference to the drawings. The degassing module of this embodiment is an application of the degassing module of this disclosure to a degassing module for degassing ink. The degassing method of this embodiment is an application of the degassing method of this disclosure to a degassing method for degassing ink. In all the figures, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0027] Figure 1 is a schematic diagram of an inkjet printer according to an embodiment. As shown in Figure 1, the inkjet printer 100 according to the embodiment mainly comprises an ink storage unit 101 such as an ink tank for storing ink, an inkjet head 102 for ejecting droplet-shaped ink, an ink flow path 103 for supplying ink from the ink storage unit 101 to the inkjet head 102, a liquid pump 104 for sending the ink in the ink flow path 103 from the ink storage unit 101 side to the inkjet head 102 side, a degassing module 1 according to an embodiment attached to the ink flow path 103 for degassing the ink, a suction pump 105 for vacuum suction, and a suction pipe 106 connecting the degassing module 1 and the suction pump 105. The ink flow path 103 has a first ink supply pipe 107 and a second ink supply pipe 108. The first ink supply pipe 107 is connected to the ink storage unit 101 and the degassing module 1 and forms an ink flow path that supplies the ink stored in the ink storage unit 101 to the degassing module 1. The second ink supply pipe 108 is connected to the degassing module 1 and the inkjet head 102, forming an ink flow path that supplies the degassed ink to the inkjet head 102. The liquid transfer pump 104 may be located at any position in the ink flow path 103, but in this embodiment, it will be described as being located in the first ink supply pipe 107. Examples of inks used in the inkjet printer 100 include pigment inks such as aqueous pigment ink, UV pigment ink, and solvent pigment ink, and ceramic ink.

[0028] Figure 2 is a schematic cross-sectional view of a degassing module according to an embodiment. Figures 3(a) and 3(b) are schematic diagrams of a part of the hollow fiber membrane bundle shown in Figure 2. Figure 4 is a cross-sectional view taken along the line IV-IV shown in Figure 2. As shown in Figures 1 to 4, the degassing module 1 comprises a hollow fiber membrane bundle 3 in which a plurality of hollow fiber membranes 2 are bundled together in a cylindrical shape, and a cylindrical housing 4 that houses the hollow fiber membrane bundle 3. The space inside the housing 4 is divided into an internal space S1 that includes the hollow portions 2a of each of the plurality of hollow fiber membranes 2, with the plurality of hollow fiber membranes 2 as the boundary, and an external space S2 that does not include the hollow portions 2a of each of the plurality of hollow fiber membranes 2. The external space S2 includes the hollow portions 3a of the hollow fiber membrane bundle 3, the space between the plurality of hollow fiber membranes 2 in the hollow fiber membrane bundle 3, and the space between the hollow fiber membrane bundle 3 and the housing 4. The hollow portion 3a is a hollow portion located in the central part in the radial direction of the hollow fiber membrane bundle 3. The degassing module 1 then degasses the ink by supplying ink to the external space S2 and simultaneously drawing in the internal space S1.

[0029] The hollow fiber membrane 2 is a hollow fiber membrane that is permeable to gases but impermeable to liquids. The hollow fiber membrane 2 has the property of swelling when exposed to liquids such as ink. The material, membrane shape, and membrane form of the hollow fiber membrane 2 are not particularly limited. Examples of materials for the hollow fiber membrane 2 include polyolefin resins such as polypropylene, polyethylene, and polymethylpentene; silicone resins such as polydimethylsiloxane and its copolymers; and fluorine resins such as PTFE and vinylidene fluoride. Examples of membrane shapes (sidewall shapes) of the hollow fiber membrane 2 include porous membranes, microporous membranes, and homogeneous membranes (non-porous membranes) that do not have porosity. Examples of membrane forms of the hollow fiber membrane 2 include symmetrical membranes (homogeneous membranes) in which the chemical or physical structure of the entire membrane is homogeneous, and asymmetrical membranes (heterogeneous membranes) in which the chemical or physical structure of the membrane differs depending on the part of the membrane. An asymmetrical membrane (heterogeneous membrane) is a membrane that has a non-porous dense layer and a porous layer. In this case, the dense layer may be formed anywhere in the membrane, such as on the surface or inside the porous membrane. Heterogeneous membranes also include composite membranes with different chemical structures and multilayer membranes such as three-layer structures. Heterogeneous membranes using poly-4-methylpentene-1 resin are particularly suitable for degassing liquids other than water, such as ink, because they have a dense layer that blocks liquids. Furthermore, when used in an external perfusion type, it is preferable that the dense layer is formed on the outer surface of the hollow fiber.

[0030] Figure 5 is a perspective view illustrating the structure of a hollow fiber membrane bundle. As shown in Figure 5, the hollow fiber membrane bundle 3 is a hollow fiber membrane sheet 10 in which multiple hollow fiber membranes 2 are connected in a curtain-like manner by multiple connecting threads 11, and this sheet is wound into a cylindrical shape. The hollow fiber membrane sheet 10 is also called a hollow fiber membrane curtain. The curtain-like manner is also called a grid-like manner. The multiple hollow fiber membranes 2 function as the weft threads of the hollow fiber membrane sheet 10, and the multiple connecting threads 11 function as the warp threads of the hollow fiber membrane sheet 10. Examples of connecting threads 11 include polyolefin resins such as polypropylene, polyethylene, and polymethylpentene; silicone resins such as polydimethylsiloxane and its copolymers; fluorine resins such as polytetrafluoroethylene (PTFE) and vinylidene fluoride; polycarbonate resins; and aromatic polyester resins such as polyethylene terephthalate. The connection between the multiple hollow fiber membranes 2 and the multiple connecting threads 11 can be carried out by, for example, knitting, weaving, bonding, welding, etc.

[0031] Figure 6 is a plan view showing a part of the hollow fiber membrane sheet. As shown in Figure 6, the spacing D1 between multiple hollow fiber membranes 2 in the hollow fiber membrane sheet 10 is 0.1 mm or more. In this case, the spacing D1 between multiple hollow fiber membranes 2 may be 0.15 mm or more, or 0.2 mm or more. Also, the spacing D1 between multiple hollow fiber membranes 2 may be 2.0 mm or less, 1.0 mm or less, or 0.5 mm or less. The spacing D1 between multiple hollow fiber membranes 2 may be, for example, the average value of the spacing between any 100 adjacent hollow fiber membranes 2. If the spacing between adjacent hollow fiber membranes 2 changes in the direction of extension of the hollow fiber membranes 2, the spacing between adjacent hollow fiber membranes 2 may be, for example, the median value of the spacing between hollow fiber membranes 2 in any 10 cm section. The median value is the midpoint between the maximum and minimum values.

[0032] The spacing D2 between the multiple connecting threads 11 in the hollow fiber membrane sheet 10 may be 8 mm or less, 6 mm or less, or 4 mm or less. Furthermore, the spacing D2 between the multiple connecting threads 11 may be 1 mm or more, 2 mm or more, or 3 mm or more.

[0033] Figures 7(a), 7(b), and 7(c) are cross-sectional views of the hollow fiber membrane bundle, showing the same cross-section as in Figure 4. Figure 8 is an enlarged cross-sectional view of a part of the hollow fiber membrane bundle, showing the same cross-section as in Figure 4. Note that each drawing shows a schematic representation of each hollow fiber membrane 2, etc., and does not represent the actual shape. As shown in Figures 7(a), 7(b), 7(c), and 8, the ratio of the sum of the apparent cross-sectional areas A2 of the hollow fiber membranes 2 to the apparent cross-sectional area A1 of the hollow fiber membrane bundle 3, A3, is defined as the hollow fiber membrane packing ratio R. The hollow fiber membrane packing ratio R will be explained in detail below.

[0034] As shown in Figure 7(a), the outer surface of the hollow fiber membrane bundle 3 is defined as the outer surface C1, and the cross-sectional region defined by the outer surface C1 is defined as the cross-sectional region a1. The cross-sectional region a1 is the area shaded with diagonal lines in Figure 7(a). The outer surface C1 is the circumferential surface that forms the outer shape of the hollow fiber membrane bundle 3. However, since the hollow fiber membrane bundle 3 is an aggregate of multiple hollow fiber membranes 2, the outer surface C1 becomes a virtual circumferential surface that abuts the outer surfaces of the multiple hollow fiber membranes 2 arranged in the outermost layer in the radial direction of the hollow fiber membrane bundle 3. In this case, one or more hollow fiber membranes 2 that have separated from the cylindrical hollow fiber membrane bundle 3 are excluded from the multiple hollow fiber membranes 2 arranged in this outermost layer.

[0035] As shown in Figure 7(b), the inner circumferential surface of the hollow fiber membrane bundle 3 is defined as the inner circumferential surface C2, and the cross-sectional region defined by the inner circumferential surface C2 is defined as the cross-sectional region a2. The cross-sectional region a2 is the area shaded by diagonal lines in Figure 7(b). The inner circumferential surface C2 is a circumferential surface that defines the hollow portion 3a, but the hollow fiber membrane bundle 3 is an aggregate of multiple hollow fiber membranes 2. Therefore, the inner circumferential surface C2 becomes a virtual circumferential surface that abuts the outer surfaces of the multiple hollow fiber membranes 2 arranged in the innermost layer in the radial direction of the hollow fiber membrane bundle 3. In this case, one or more hollow fiber membranes 2 that have separated from the cylindrical hollow fiber membrane bundle 3 are excluded from the multiple hollow fiber membranes 2 arranged in this innermost layer.

[0036] As shown in Figures 7(a), 7(b), and 7(c), the region obtained by subtracting cross-sectional region a2 from cross-sectional region a1 is defined as cross-sectional region a3. Cross-sectional region a3 is the region shaded with diagonal lines in Figure 7(c). The area of ​​this cross-sectional region a3 becomes the apparent cross-sectional area A1 of the hollow fiber membrane bundle 3.

[0037] As shown in Figure 8, the outer surface of a single hollow fiber membrane 2 is defined as the outer surface C3, and the cross-sectional area defined by the outer surface C3 is defined as the cross-sectional area a4. The cross-sectional area a4 is the area shaded by diagonal lines in Figure 8. In other words, the cross-sectional area a4 is the sum of the cross-sectional area of ​​the membrane body 2b of the cylindrically formed hollow fiber membrane 2 and the cross-sectional area of ​​the hollow portion 2a of the hollow fiber membrane 2. The area of ​​the cross-sectional area a4 becomes the apparent cross-sectional area A2 of the hollow fiber membrane 2. If N is the number of hollow fiber membranes 2 that make up the hollow fiber membrane bundle 3, then the value obtained by multiplying the apparent cross-sectional area A2 by N is the sum of the apparent cross-sectional areas A2 of the hollow fiber membranes 2, A3. In other words, the sum of the apparent cross-sectional areas A2 of the hollow fiber membranes 2, A3, is calculated by the formula A2 × N. In addition, the gaps G between the hollow fiber membranes 2 in the hollow fiber membrane bundle 3 are excluded from the sum of the apparent cross-sectional areas A2 of the hollow fiber membranes 2, A3.

[0038] Therefore, the hollow fiber membrane packing ratio R is calculated using the formula ((A2 × N) / A1) × 100. The hollow fiber membrane packing ratio R may be 90% or less, 60% or less, or 40% or less. Furthermore, the hollow fiber membrane packing ratio R may be 10% or more, 20% or more, or 30% or more. The hollow fiber membrane packing ratio R can be adjusted, for example, by adjusting the spacing D1 between the multiple hollow fiber membranes 2 in the hollow fiber membrane sheet 10, the thickness of each of the multiple hollow fiber membranes 2, the winding force of the hollow fiber membrane sheet 10, etc.

[0039] Here, when treated with organic solvents such as glycols, glycol monoalkyl ethers, glycol dialkyl ethers, glycol monoacetates, glycol diacetates, alcohols, ketones, acetate esters, and lactic acid esters, or with solvents such as saturated hydrocarbons, unsaturated hydrocarbons, cyclic saturated hydrocarbons, cyclic unsaturated hydrocarbons, aromatic hydrocarbons, terpenes, cyclic imides, oxazolines, N-alkylpyrrolidones, and nitrogen-containing solvents used in ceramic inks, the hollow fiber membrane 2 swells. For this reason, when using ink containing these solvents as the ink used in the inkjet printer 100, it is preferable that the hollow fiber membrane packing ratio R be low, for example, 40% or less.

[0040] As shown in Figure 2, the housing 4 comprises a cylindrical portion 5, a first lid portion 6, and a second lid portion 7.

[0041] As shown in Figures 2 and 4, the cylindrical portion 5 is the part that houses the hollow fiber membrane bundle 3. The cylindrical portion 5 is formed in a cylindrical shape with both ends open. The hollow fiber membrane bundle 3 is housed in the cylindrical portion 5 such that the direction of extension of the cylindrical portion 5 and the direction of extension of the hollow fiber membrane bundle 3 are substantially the same. The first membrane bundle end 3b, which is one end of the hollow fiber membrane bundle 3, is fixed to the first open end 5a, which is one end of the cylindrical portion 5, by the first fixing part 8. The second membrane bundle end 3c, which is the other end of the hollow fiber membrane bundle 3, is fixed to the second open end 5b, which is the other end of the cylindrical portion 5, by the second fixing part 9.

[0042] As shown in Figures 2 and 3(a), the first fixing part 8 is made of resin. Examples of resins used for the first fixing part 8 include epoxy resin, urethane resin, ultraviolet curing resin, and polyolefin resins such as polyethylene and polypropylene. At the first membrane bundle end 3b, the first fixing part 8 seals the hollow portions 2a of each of the multiple hollow fiber membranes 2 and opens the hollow portion 3a of the hollow fiber membrane bundle 3. In other words, the first fixing part 8 fills the hollow portions 2a of each of the multiple hollow fiber membranes 2, the spaces between the multiple hollow fiber membranes 2 in the hollow fiber membrane bundle 3, and the space between the hollow fiber membrane bundle 3 and the cylindrical part 5. In a cross section perpendicular to the extending direction of the hollow fiber membrane bundle 3, passing through the first membrane bundle end 3b, the first fixing part 8 seals the area within the cylindrical part 5 other than the hollow portion 3a of the hollow fiber membrane bundle 3. The first fixing part 8 has a communication opening 8a that opens the hollow portion 3a of the hollow fiber membrane bundle 3 to the outside of the cylindrical part 5. The first fixing portion 8 may be provided in a part of the hollow portion 3a of the hollow fiber membrane bundle 3, provided that the hollow portion 3a of the hollow fiber membrane bundle 3 is open.

[0043] As shown in FIGS. 2 and 3(b), the second fixing portion 9 is formed of the same resin as the first fixing portion 8. The second fixing portion 9 seals, in a cross-section perpendicular to the extending direction of the hollow fiber membrane bundle 3 through the second membrane bundle end portion 3c, regions other than the respective hollow portions 2a of the plurality of hollow fiber membranes 2 within the cylindrical portion 5. That is, the second fixing portion 9 is not filled in the respective hollow portions 2a of the plurality of hollow fiber membranes 2, and is filled between the plurality of hollow fiber membranes 2 in the hollow fiber membrane bundle 3, between the hollow fiber membrane bundle 3 and the cylindrical portion 5, and in the hollow portion 3a of the hollow fiber membrane bundle 3. The degassing module 1 is arranged in the inkjet printer 100 such that the second fixing portion 9 is arranged below the first fixing portion 8 and the suction port 7a is arranged at the lower part of the degassing module 1.

[0044] As shown in FIG. 2, the separation distance D3 between the cylindrical portion 5 and the hollow fiber membrane bundle 3 may be 0.1 mm or more, may be 0.5 mm or more, or may be 1 mm or more. Also, the separation distance D3 between the cylindrical portion 5 and the hollow fiber membrane bundle 3 may be 30 mm or less, may be 10 mm or less, or may be 5 mm or less. The separation distance D3 between the cylindrical portion 5 and the hollow fiber membrane bundle 3 can be adjusted, for example, by adjusting the fixing positions of the first membrane bundle end portion 3b by the first fixing portion 8 and the second membrane bundle end portion 3c by the second fixing portion 9.

[0045] A liquid supply port 5c is formed in the side wall of the cylindrical portion 5. The liquid supply port 5c is an opening formed in the cylindrical portion 5 for supplying ink to the external space S2. The liquid supply port 5c is formed between the first fixing portion 8 and the second fixing portion 9 and opens to the external space S2 between the first fixing portion 8 and the second fixing portion 9. The liquid supply port 5c may be formed on the side of the second fixing portion 9 rather than the center in the extending direction of the cylindrical portion 5. Also, the liquid supply port 5c may be formed in the vicinity of the second fixing portion 9. A first ink supply pipe 107 is connected to the liquid supply port 5c (see FIG. 1). The liquid supply port 5c and the first ink supply pipe 107 are detachably connected, for example, by screwing, fitting, etc.

[0046] The first lid portion 6 is formed in a shape that tapers as it moves away from the cylindrical portion 5. A liquid discharge port 6a is formed at the tip of the first lid portion 6. The liquid discharge port 6a is an opening formed in the first lid portion 6 for discharging ink from the external space S2. By being formed in the first lid portion 6, the liquid discharge port 6a is formed on the side opposite to the second fixing portion 9 with respect to the first fixing portion 8 of the housing 4. That is, the liquid discharge port 6a is formed at the upper part of the housing 4. A second ink supply pipe 108 is connected to the liquid discharge port 6a (see FIG. 1). The liquid discharge port 6a and the second ink supply pipe 108 are detachably connected, for example, by screwing, fitting, etc. A first space S3 is formed inside the first lid portion 6. The first space S3 is the external space S2 and is communicated with the liquid discharge port 6a and the hollow portion 3a of the hollow fiber membrane bundle 3.

[0047] The second lid portion 7 is formed in a shape that tapers as it moves away from the cylindrical portion 5. A suction port 7a is formed at the tip of the second lid portion 7. The suction port 7a is an opening formed in the second lid portion 7 for sucking the respective hollow portions 2a of the plurality of hollow fiber membranes 2. By being formed in the second lid portion 7, the suction port 7a is formed on the side opposite to the first fixing portion 8 with respect to the second fixing portion 9 of the housing 4. That is, the suction port 7a is formed at the lower part of the housing 4. A suction pipe 106 is connected to the suction port 7a (see FIG. 1). The suction port 7a and the suction pipe 106 are detachably connected, for example, by screwing, fitting, etc. A second space S4 is formed inside the second lid portion 7. The second space S4 is the internal space S1 and is communicated with the suction port 7a and the respective hollow portions 2a of the plurality of hollow fiber membranes 2. The suction port 7a opens, for example, at the lowermost part of the second space S4.

[0048] Next, an ink degassing method using the degassing module 1 in the inkjet printer 100 will be described.

[0049] As shown in Figures 1 and 2, when degassing the ink, ink is supplied from the ink storage unit 101 to the first ink supply pipe 107, and the internal space S1 of the degassing module 1 is sucked by the suction pump 105. The ink supplied from the ink storage unit 101 to the first ink supply pipe 107 is supplied to the external space S2 of the degassing module 1 from the liquid supply port 5c. The ink supplied to the external space S2 flows from the outside of the hollow fiber membrane bundle 3 through the gaps between the multiple hollow fiber membranes 2 to the hollow portion 3a. At this time, because the internal space S1 is being sucked by the suction pump 105, the hollow portions 2a of each of the multiple hollow fiber membranes 2 are under reduced pressure. Therefore, as the ink passes between the multiple hollow fiber membranes 2, dissolved gases and gases such as bubbles in the ink permeate through each of the multiple hollow fiber membranes 2 and are drawn into the hollow portions 2a of each of the multiple hollow fiber membranes 2. This is how the ink is degassed. The degassed ink is discharged from the liquid discharge port 6a to the second ink supply pipe 108 through the hollow portion 3a of the hollow fiber membrane bundle 3, the communication port 8a of the first fixed portion 8, and the first space S3. The ink discharged to the second ink supply pipe 108 is supplied to the inkjet head 102 through the second ink supply pipe 108. The gas drawn into the hollow portion 2a of each of the multiple hollow fiber membranes 2 is discharged from the suction port 7a to the suction pipe 106 through the hollow portion 2a of each of the multiple hollow fiber membranes 2 and the second space S4.

[0050] As described above, in the degassing module 1 according to this embodiment, when the suction port 7a is drawn and ink (liquid) is supplied to the liquid supply port 5c, the ink is degassed as it passes between the multiple hollow fiber membranes 2. The hollow fiber membrane bundle 3 is made of a hollow fiber membrane sheet 10 in which multiple hollow fiber membranes 2 are connected in a curtain-like manner by multiple connecting threads 11, and this sheet is wound into a cylindrical shape. The spacing D1 between the multiple hollow fiber membranes 2 in the hollow fiber membrane sheet 10 is 0.1 mm or more, 0.15 mm or more, or 0.2 mm or more. Therefore, even if components of the ink precipitate on the surface of the multiple hollow fiber membranes 2, it is possible to suppress the narrowing of the gaps between the multiple hollow fiber membranes 2 to the point where the degassing module 1 becomes clogged with ink. This prevents the degassing module 1 from becoming clogged.

[0051] Furthermore, in this degassing module 1, the spacing D1 between the multiple hollow fiber membranes 2 in the hollow fiber membrane sheet 10 is 2.0 mm or less, 1.0 mm or less, or 0.5 mm or less. Therefore, it is possible to ensure a sufficient number of hollow fiber membranes 2 to adequately degass the ink.

[0052] Furthermore, in this degassing module 1, the spacing D2 between the multiple connecting threads 11 in the hollow fiber membrane sheet 10 is 8 mm or less, 6 mm or less, or 4 mm or less. Therefore, when the multiple hollow fiber membranes 2 swell, they are more likely to undulate or spread out. As a result, the gaps between the multiple hollow fiber membranes 2 widen, further suppressing clogging of the degassing module 1.

[0053] Furthermore, in this degassing module 1, the spacing D2 between the multiple connecting threads 11 in the hollow fiber membrane sheet 10 is 1 mm or more, 2 mm or more, or 3 mm or more. Therefore, when the multiple hollow fiber membranes 2 swell, it is possible to suppress the multiple hollow fiber membranes 2 from being pressed against the housing 4 due to the waviness and spreading of the multiple hollow fiber membranes 2.

[0054] Furthermore, in this degassing module 1, the hollow fiber membrane packing ratio R is 90% or less, 60% or less, or 40% or less. Therefore, even if ink components precipitate on the surface of multiple hollow fiber membranes 2, it is possible to suppress the narrowing of the gaps between the multiple hollow fiber membranes 2 to the point where the degassing module 1 becomes clogged with ink. This further suppresses clogging of the degassing module 1.

[0055] Furthermore, in this degassing module 1, the hollow fiber membrane packing ratio R is 10% or more, 20% or more, or 30% or more. Therefore, it is possible to secure a sufficient number of hollow fiber membranes 2 to adequately degass the ink.

[0056] Furthermore, in this degassing module 1, the separation distance D3 between the cylindrical portion 5 and the hollow fiber membrane bundle 3 is 0.1 mm or more, 0.5 mm or more, or 1 mm or more. Therefore, when the multiple hollow fiber membranes 2 swell, it is possible to suppress the multiple hollow fiber membranes 2 from being pressed against the cylindrical portion 5. This further suppresses clogging of the degassing module 1.

[0057] Furthermore, in this degassing module 1, the separation distance D3 between the cylindrical portion 5 and the hollow fiber membrane bundle 3 is 30 mm or less, 10 mm or less, or 5 mm or less. Therefore, it is possible to secure a sufficient number of hollow fiber membranes 2 to adequately degass the ink.

[0058] Furthermore, in this degassing module 1, the first fixing part 8 fixes the first membrane bundle end 3b to the cylindrical part 5, sealing the hollow portions 2a of each of the multiple hollow fiber membranes 2 at the first membrane bundle end 3b, while leaving the hollow portions 3a of the hollow fiber membrane bundle 3 open. In addition, the second fixing part 9 fixes the second membrane bundle end 3c to the cylindrical part 5, sealing the area within the housing 4 other than the hollow portions 2a of each of the multiple hollow fiber membranes 2 in a cross section perpendicular to the extending direction of the hollow fiber membrane bundle 3 passing through the second membrane bundle end 3c. As a result, the first fixing part 8 and the second fixing part 9 divide the space within the housing 4 into an internal space S1 that includes the hollow portions 2a of each of the multiple hollow fiber membranes 2, with the multiple hollow fiber membranes 2 as the boundary, and an external space S2 that does not include the hollow portions 2a of each of the multiple hollow fiber membranes 2. Furthermore, the suction port 7a is formed on the side of the housing 4 opposite to the first fixing part 8 relative to the second fixing part 9, the liquid supply port 5c is formed between the first fixing part 8 and the second fixing part 9 of the housing 4, and the liquid discharge port 6a is formed on the side of the housing 4 opposite to the second fixing part 9 relative to the first fixing part 8. Therefore, by drawing suction into the suction port 7a and supplying ink to the liquid supply port 5c, the ink can be degassed, and the degassed ink can be discharged from the liquid discharge port 6a.

[0059] In the inkjet printer 100 according to this embodiment, since the degassing module 1 is attached to the ink flow path 103, clogging of the degassing module 1 can be suppressed, thereby preventing ink ejection failures.

[0060] Furthermore, in this inkjet printer 100, the suction port 7a of the degassing module 1 is located at the bottom of the degassing module 1. Therefore, even if liquid components such as water vapor contained in the gas that has permeated through the multiple hollow fiber membranes 2 liquefy in the internal space S1, or if liquid permeates through the multiple hollow fiber membranes 2, this liquid can be discharged from the degassing module 1 through the suction port 7a by gravity. This prevents the internal space S1 of the degassing module 1 from becoming clogged with liquid.

[0061] Furthermore, in this inkjet printer 100, the first fixing part 8 fixes the first membrane bundle end 3b to the cylindrical part 5, sealing the hollow portions 2a of each of the multiple hollow fiber membranes 2 at the first membrane bundle end 3b, while leaving the hollow portions 3a of the hollow fiber membrane bundle 3 open. In addition, the second fixing part 9 fixes the second membrane bundle end 3c to the cylindrical part 5, sealing the area within the housing 4 other than the hollow portions 2a of each of the multiple hollow fiber membranes 2 in a cross section perpendicular to the extending direction of the hollow fiber membrane bundle 3 passing through the second membrane bundle end 3c. As a result, the first fixing part 8 and the second fixing part 9 divide the space within the housing 4 into an internal space S1 that includes the hollow portions 2a of each of the multiple hollow fiber membranes 2, with the multiple hollow fiber membranes 2 as the boundary, and an external space S2 that does not include the hollow portions 2a of each of the multiple hollow fiber membranes 2. The suction port 7a is formed on the side of the housing 4 opposite to the first fixing part 8 relative to the second fixing part 9. Therefore, by drawing air through the suction port 7a, the ink flowing through the ink channel 103 can be degassed. Furthermore, the second fixing part 9 is positioned below the first fixing part 8, the liquid supply port 5c is formed between the first fixing part 8 and the second fixing part 9 of the housing 4, and the liquid discharge port 6a is formed on the side of the housing 4 opposite to the second fixing part 9 relative to the first fixing part 8. As a result, the ink supplied from the liquid supply port 5c flows upwards, sweeping up the ink in the external space S2, and is discharged from the liquid discharge port 6a. This prevents the accumulation of ink components at the bottom of the external space S2.

[0062] In the degassing method according to this embodiment, the suction port 7a of the degassing module 1 is suctioned, and liquid ink is supplied to the liquid supply port 5c of the degassing module 1, thereby preventing clogging of the degassing module 1 while degassing the liquid ink.

[0063] While preferred embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above.

[0064] For example, the degassing module may include an inner support that is positioned in the hollow portion of the hollow fiber membrane bundle and supports the hollow fiber membrane bundle from the inner circumferential side, as shown in the modified degassing module 1A in Figure 9. Alternatively, the degassing module may include an outer support that is positioned between the hollow fiber membrane bundle and the housing and supports the hollow fiber membrane bundle from the outer circumferential side, as shown in the modified degassing module 1A in Figure 9.

[0065] Figure 9 is a schematic cross-sectional view of a modified degassing module. Figure 10 is a cross-sectional view taken along the line X-X shown in Figure 9. The modified degassing module 1A shown in Figure 9 is basically the same as the degassing module 1 of the above embodiment, but differs from the degassing module 1 of the above embodiment in that it further comprises an inner support 12 and an outer support 13.

[0066] The inner support 12 is positioned in the hollow portion 3a of the hollow fiber membrane bundle 3 and is a member for supporting the hollow fiber membrane bundle 3 (multiple hollow fiber membranes 2) from the inner circumference (radially inward). The inner support 12 is fixed to the cylindrical portion 5 by a first fixing portion 8 and a second fixing portion 9, similar to the hollow fiber membrane bundle 3. The inner support 12 is formed in a cylindrical (pipe) shape. The outer diameter of the inner support 12 is approximately the same as the inner diameter of the hollow fiber membrane bundle 3. The thickness of the inner support 12 can be appropriately set within a range that can support multiple swollen hollow fiber membranes 2. The inner support 12 has multiple openings 12a formed therein for ink to pass through. The inner support 12 is formed in a mesh (net) shape, for example. If the inner support 12 is formed in a mesh shape, its multiple mesh openings become multiple openings 12a.

[0067] The outer support 13 is positioned between the hollow fiber membrane bundle 3 and the cylindrical portion 5 and is a member for supporting the hollow fiber membrane bundle 3 (a plurality of hollow fiber membranes 2) from the outer circumference (radially outward). The outer support 13 is fixed to the cylindrical portion 5 by a first fixing portion 8 and a second fixing portion 9, similar to the hollow fiber membrane bundle 3. The outer support 13 is formed in a cylindrical (pipe-like) shape. The inner diameter of the outer support 13 is greater than or equal to the outer diameter of the hollow fiber membrane bundle 3 and less than or equal to the inner diameter of the cylindrical portion 5. The outer support 13 may be in contact with the hollow fiber membrane bundle 3, in contact with the cylindrical portion 5, or spaced apart from the hollow fiber membrane bundle 3 and the cylindrical portion 5. The thickness of the outer support 13 can be appropriately set, for example, within a range that can support a plurality of swollen hollow fiber membranes 2. The outer support 13 has a plurality of openings 13a formed therein for allowing ink to pass through. The outer support 13 is formed in a mesh (net-like) shape, for example. If the outer support 13 is formed in a mesh-like structure, the multiple mesh openings become multiple openings 13a.

[0068] The inner support 12 and the outer support 13 are preferably made of resin, for example, from the viewpoint of ease of manufacture. Examples of resins used for the inner support 12 and the outer support 13 include polypropylene, polyethylene, preferably ultra-high molecular weight polyethylene, and high-density polyethylene.

[0069] As described above, in the modified degassing module 1A, the hollow fiber membrane bundle 3 is supported from the inner circumference by the inner support 12. Therefore, when the multiple hollow fiber membranes 2 swell, it is possible to prevent the multiple hollow fiber membranes 2 from entering the hollow portion 3a of the hollow fiber membrane bundle 3 and narrowing or blocking the hollow portion 3a. This makes it possible to suppress an increase in the pressure loss of the liquid flowing through the hollow portion 3a of the hollow fiber membrane bundle 3.

[0070] Furthermore, in the modified degassing module 1A, the hollow fiber membrane bundle 3 is supported from the outer periphery by the outer support 13. This prevents the multiple hollow fiber membranes 2 from being pressed against the cylindrical portion 5 when they swell. This further prevents the degassing module 1A from becoming clogged.

[0071] Furthermore, the degassing module may also be equipped with an outlet for discharging liquid from the internal space, such as the modified degassing module 1B shown in Figure 11.

[0072] Figure 11 is a schematic cross-sectional view of a modified degassing module. The modified degassing module 1B shown in Figure 11 is basically the same as the degassing module 1 of the above embodiment, but differs from the degassing module 1 of the above embodiment in that it further includes an outlet 14 for discharging ink from the internal space S1.

[0073] The discharge port 14 is an opening for discharging ink from the internal space S1 and is formed in the second lid portion 7. By being formed in the second lid portion 7, the discharge port 14 is formed on the opposite side of the housing 4 from the first fixing portion 8 relative to the second fixing portion 9. In other words, the discharge port 14 is formed in the lower part of the housing 4 and opens into the second space S4.

[0074] In this modified degassing module 1B, an outlet 14 for discharging ink from the internal space S1 is formed on the side opposite to the first fixing part 8 relative to the second fixing part 9 of the housing 4. Therefore, even if liquid components such as water vapor contained in the gas that has permeated through the multiple hollow fiber membranes 2 liquefy in the internal space S1, or if liquid permeates through the multiple hollow fiber membranes 2, this liquid can be discharged from the outlet 14. This prevents the internal space S1, the suction pipe 106 connected to the suction port 7a, and the suction pump 105 from becoming clogged with liquid.

[0075] Furthermore, for example, an inkjet printer may be provided with a return pipe to return ink from the inkjet head to the ink reservoir, as shown in the modified inkjet printer 100C in Figure 12, thereby circulating the ink.

[0076] Figure 12 is a schematic diagram of a modified inkjet printer. The modified inkjet printer 100C shown in Figure 12 is basically the same as the inkjet printer 100 of the above embodiment, but differs from the inkjet printer 100 of the above embodiment in that it further includes a return pipe 110 and a liquid supply pump 111.

[0077] The return pipe 110 is connected to the inkjet head 102 and the ink storage unit 101, forming an ink flow path that returns ink from the inkjet head 102 to the ink storage unit 101. The liquid transfer pump 111 is attached to the return pipe 110 and is a pump that sends the ink in the return pipe 110 from the inkjet head 102 side to the ink storage unit 101 side.

[0078] Thus, in the modified inkjet printer 100C, ink can be returned from the inkjet head 102 to the ink storage unit 101, allowing for ink reuse and reducing ink consumption.

[0079] Furthermore, an inkjet printer may be equipped with a heating device for heating the ink flow path, such as the modified inkjet printer 100D shown in Figure 13.

[0080] Figure 13 is a schematic diagram of a modified inkjet printer. The modified inkjet printer 100D shown in Figure 13 is basically the same as the inkjet printer 100 of the above embodiment, but differs from the inkjet printer 100 of the above embodiment in that it further includes a heating device 109.

[0081] The heating device 109 heats the ink channel 103. The heating device 109 may also heat the second ink supply pipe 108. By heating the ink channel 103, the heating device 109 heats the ink in the ink channel 103. The heating device 109 includes, for example, a heating element such as an electric heating wire, an insulating element that covers the heating element, and a power supply that supplies power to the heating element. The heating element and the insulating element are attached to the position in the ink channel 103 that is to be heated. The heating element and the insulating element can be attached to the ink channel 103 by, for example, wrapping the heating element and the insulating element around the ink channel 103. The heating element and the insulating element may also be attached to the second ink supply pipe 108. The heating device 109 may also heat the degassing module 1 by arranging to cover at least a part of the degassing module 1. In this case, the heating device 109 heats the ink in the degassing module 1 by heating the degassing module 1. Furthermore, the heating device 109 may be positioned to cover at least a portion of the liquid transfer pump 104, thereby also heating the liquid transfer pump 104. In this case, the heating device 109 heats the ink inside the liquid transfer pump 104 by heating the liquid transfer pump 104.

[0082] Thus, in the modified inkjet printer 100D, the heating device 109 can heat the ink in the ink channel 103 by heating the ink channel 103. Therefore, even if the ink components solidify in the ink channel 103 due to a long period of ink flow cessation, the heating device 109 can redissolve the solidified ink components. This makes it possible to suppress clogging of the inkjet head 102 due to solidified ink components.

[0083] Furthermore, for example, an inkjet printer may be equipped with a suction tube that has a discharge device for discharging liquid from the suction tube, such as the modified inkjet printer 100E shown in Figure 14.

[0084] Figure 14 is a schematic diagram of a modified inkjet printer. The modified inkjet printer 100E shown in Figure 14 is basically the same as the inkjet printer 100 of the above embodiment, but differs from the inkjet printer 100 of the above embodiment in that it further includes an ejection device 112.

[0085] The discharge device 112 is a device for discharging liquid from the suction pipe 106. The discharge device 112 is attached to the suction pipe 106 and discharges the liquid inside the suction pipe 106 between the degassing module 1 and the suction pump 105. The discharge device 112 can be configured as a drain system comprising, for example, a separator that separates the liquid from the gas flowing through the suction pipe 106, a drain trap that collects the liquid separated by the separator, and a drain valve that automatically or manually discharges the liquid collected in the drain trap.

[0086] Thus, in the modified inkjet printer 100E, the discharge device 112 discharges liquid from the suction tube 106 connected to the suction port 7a. Therefore, even if liquid components such as water vapor contained in the gas that has permeated through the multiple hollow fiber membranes 2 liquefy in the internal space S1, or if liquid permeates through the multiple hollow fiber membranes 2, this liquid can be discharged in the suction tube 106. This prevents the suction pump 105 from malfunctioning due to being sucked in liquid.

[0087] Furthermore, although ink was used as an example of the liquid to be degassed in the above embodiment, the liquid to be degassed may be a liquid other than ink.

[0088] Furthermore, although the above embodiment describes the cylindrical portion, the first lid portion, and the second lid portion constituting the housing as separate parts, they may also be formed as a single unit.

[0089] 1... Degassing module, 1A... Degassing module, 1B... Degassing module, 2... Hollow fiber membrane, 2a... Hollow section, 2b... Membrane body, 3... Hollow fiber membrane bundle, 3a... Hollow section, 3b... First membrane bundle end, 3c... Second membrane bundle end, 4... Housing, 5... Cylindrical section, 5a... First open end, 5b... Second open end, 5c... Liquid supply port, 6... First lid, 6a... Liquid discharge port, 7... Second lid, 7a... Suction port, 8... First fixing section, 8a... Communication port, 9... Second fixing section, 10... Hollow fiber membrane sheet, 11... Connecting thread, 12... Inner support, 12a... Opening, 13... Outer support, 13a... Opening, 14... Discharge port, 100... Inkjet printer, 100C... Inkjet printer, 100D... Inkjet A1...Inkjet printer, 100E...Ink storage unit, 102...Inkjet head, 103...Ink flow path, 104...Ink delivery pump, 105...Suction pump, 106...Suction tube, 107...First ink supply tube, 108...Second ink supply tube, 109...Heating device, 110...Return tube, 111...Ink delivery pump, 112...Discharge device, A1...Apparent cross-sectional area, A2...Apparent cross-sectional area, A3...Total, a1...Cross-sectional area, a2...Cross-sectional area, a3...Cross-sectional area, a4...Cross-sectional area, C1...Outer surface, C2...Inner surface, C3...Outer surface, D1...Spacing, D2...Spacing, D3...Separation distance, G...Gap, S1...Internal space, S2...External space, S3...First space, S4...Second space.

Claims

1. A degassing module comprising: a hollow fiber membrane bundle in which a plurality of hollow fiber membranes are bundled together in a cylindrical shape; and a housing that houses the hollow fiber membrane bundle, wherein the space within the housing is divided by the plurality of hollow fiber membranes into an internal space including the hollow portion of each of the plurality of hollow fiber membranes and an external space not including the hollow portion of each of the plurality of hollow fiber membranes, the housing has a suction port communicating with the internal space and a liquid supply port and a liquid discharge port communicating with the external space, the hollow fiber membrane bundle is a hollow fiber membrane sheet in which the plurality of hollow fiber membranes are connected in a curtain-like manner by a plurality of connecting threads and wound into a cylindrical shape, and the spacing between the plurality of hollow fiber membranes in the hollow fiber membrane sheet is 0.1 mm or more.

2. The degassing module according to claim 1, wherein the spacing between the plurality of connecting threads in the hollow fiber membrane sheet is 8 mm or less.

3. The degassing module according to claim 1 or 2, wherein the hollow fiber membrane packing ratio, which is the ratio of the sum of the apparent cross-sectional areas of the hollow fiber membranes to the apparent cross-sectional area of ​​the hollow fiber membrane bundle, is 90% or less.

4. The degassing module according to any one of claims 1 to 3, wherein the distance between the housing and the hollow fiber membrane bundle is 0.1 mm or more.

5. The degassing module according to any one of claims 1 to 4, further comprising an inner support disposed in the hollow portion of the hollow fiber membrane bundle and supporting the hollow fiber membrane bundle from the inner circumferential side.

6. The degassing module according to any one of claims 1 to 5, further comprising an outer support disposed between the hollow fiber membrane bundle and the housing and supporting the hollow fiber membrane bundle from the outer periphery.

7. A degassing module according to any one of claims 1 to 6, further comprising: a first fixing portion that fixes one end of the hollow fiber membrane bundle, which is a first membrane bundle end, to the housing, and at the first membrane bundle end, seals the hollow portion of each of the plurality of hollow fiber membranes and opens the hollow portion of the hollow fiber membrane bundle; and a second fixing portion that fixes the other end of the hollow fiber membrane bundle, which is a second membrane bundle end, to the housing, and in a cross section passing through the second membrane bundle end and perpendicular to the extending direction of the hollow fiber membrane bundle, seals the area in the housing other than the hollow portion of each of the plurality of hollow fiber membranes, wherein the suction port is formed on the side of the housing opposite to the first fixing portion relative to the second fixing portion; the liquid supply port is formed between the first fixing portion and the second fixing portion of the housing; and the liquid discharge port is formed on the side of the housing opposite to the second fixing portion relative to the first fixing portion.

8. The degassing module according to claim 7, further comprising a discharge port formed on the side of the housing opposite to the first fixing portion relative to the second fixing portion for discharging liquid from the internal space.

9. An inkjet printer comprising: an inkjet head; an ink channel for supplying ink to the inkjet head; and a degassing module according to any one of claims 1 to 8, attached to the ink channel.

10. The inkjet printer according to claim 9, wherein the suction port of the degassing module is located at the bottom of the degassing module.

11. The inkjet printer according to claim 10, further comprising a suction tube connected to the suction port and a discharge device for discharging liquid from the suction tube.

12. The degassing module further comprises: a first fixing portion that fixes one end of the hollow fiber membrane bundle, which is a first membrane bundle end, to the housing, and at the first membrane bundle end, seals the hollow portion of each of the plurality of hollow fiber membranes and opens the hollow portion of the hollow fiber membrane bundle; a second fixing portion that fixes the other end of the hollow fiber membrane bundle, which is a second membrane bundle end, to the housing, and in a cross section passing through the second membrane bundle end and perpendicular to the extending direction of the hollow fiber membrane bundle, seals the area in the housing other than the hollow portion of each of the plurality of hollow fiber membranes, and is located below the first fixing portion, wherein the suction port is formed on the housing opposite to the first fixing portion relative to the second fixing portion; the liquid supply port is formed between the first fixing portion and the second fixing portion of the housing; and the liquid discharge port is formed on the housing opposite to the second fixing portion relative to the first fixing portion, the inkjet printer according to any one of claims 9 to 11.

13. The inkjet printer according to any one of claims 9 to 12, further comprising a heating device for heating the ink flow path.

14. A degassing method for degassing a liquid using a degassing module according to any one of claims 1 to 8, comprising: sucking the suction port of the degassing module and supplying the liquid to the liquid supply port of the degassing module.

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