Inkjet recording method and inkjet recording apparatus

Abstract

The present invention relates to an inkjet recording method for recording an image by ejecting ink from an inkjet head (24a), comprising: a main ink tank (51) as an ink supply source, a first auxiliary ink tank (241) connected to the main ink tank (51) and supplying ink, a degassing device connected to the first auxiliary ink tank (241) and degassing the ink supplied from the first auxiliary ink tank (241); a second auxiliary ink tank (245) for supplying the ink degassed by the degassing device to the inkjet head (24a) and controlling the negative pressure applied to the inkjet head (24a); and a heating device (270) for heating the flow path of the ink of at least the first auxiliary ink tank (241), and further comprising a control unit (40) for conveying the ink in such a manner that the amount of ink newly supplied from the main ink tank (51) to the first auxiliary ink tank (241) is greater than the amount of ink remaining in the first auxiliary ink tank (241), wherein the ink is a free radical polymerizable ink containing a thermosetting component.

Description

Technical Field

[0001] The present invention relates to an inkjet recording method and an inkjet recording apparatus, and more particularly to an inkjet recording method and an inkjet recording apparatus having excellent coating durability, solder heat resistance, and ejection stability. Background Art

[0002] Free radical-curing UV inks are commonly used for solder mask production. Free radical-curing UV inks can sometimes cause unintended polymerization (hereinafter referred to as "thermal polymerization") due to free radical species generated within the ink system. These free radical species are captured by polymerization inhibitors and oxygen in the ink system, but if the amount of free radical species generated continues to increase, there is a risk that these free radical species will not be completely captured and may react with monomers, causing polymerization.

[0003] On the other hand, unlike conventional marking in inkjet printing on printed circuit boards, solder mask printing, like graphic printing, requires high print volume and high-duty printing, and also requires high productivity. It is known that in such inkjet recording devices, degassing the ink to suppress cavitation is effective in order to improve the ejection reliability of the inkjet head (see, for example, Patent Document 1).

[0004] In addition, in order to improve the durability of the coating film used as a solder resist mask, a thermosetting component is generally contained in the ink. When the amount of such a functional component added is increased to improve the durability of the coating film, the viscosity of the ink increases.

[0005] Therefore, in order to match the optimal viscosity range for dispensing, the ink needs to be heated at a higher temperature than that of conventional UV inks. In addition, as mentioned above, ink degassing is required to improve dispensing reliability. Since heating and degassing are required, the risk of thermal polymerization must be suppressed when handling solder mask ink.

[0006] It should be noted that although there have been inventions in the past for systems that supply ink while degassing under high temperature conditions of about 60 to 90°C, systems in which the ink itself contains thermosetting components have not been discovered so far (for example, see Patent Documents 2 and 3).

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2007-136957

[0010] Patent Document 2: Japanese Patent No. 6708128

[0011] Patent Document 3: Japanese Patent No. 6036543 Summary of the Invention

[0012] The present invention has been made in view of the above-mentioned problems and circumstances, and aims to provide an inkjet recording method and an inkjet recording apparatus which have excellent coating durability and solder heat resistance, and which do not cause ink viscosity increase or polymerization reaction even under ink degassing, and can stably discharge ink for a long period of time.

[0013] In order to solve the above-mentioned problems, the inventors conducted research on the causes of the above-mentioned problems and found that by controlling the amount of ink newly supplied from the main ink tank to the first sub-ink tank to be greater than the amount of ink remaining in the first sub-ink tank, the coating durability, solder heat resistance and ejection stability are excellent even when using free radical polymerizable ink containing thermosetting components, thereby completing the present invention.

[0014] That is, the above-mentioned problems of the present invention can be solved by the following means.

[0015] 1. An inkjet recording method for recording an image by ejecting ink from an inkjet head, comprising:

[0016] The main ink tank serves as the ink supply source;

[0017] a first auxiliary ink tank connected to the main ink tank to supply ink;

[0018] a degassing device connected to the first auxiliary ink tank and degassing the ink supplied from the first auxiliary ink tank;

[0019] a second auxiliary ink tank for supplying the ink degassed by the degassing device to the inkjet head and controlling the negative pressure applied to the inkjet head; and

[0020] a heating device for heating at least the ink flow path of the first auxiliary ink tank;

[0021] The ink tank further includes a control unit configured to transport the ink so that the amount of ink newly supplied from the main ink tank to the first sub-ink tank is greater than the amount of ink remaining in the first sub-ink tank.

[0022] The above ink is a radical polymerizable ink containing a thermosetting component.

[0023] 2. The inkjet recording method according to the first item, wherein the control unit intermittently feeds the ink from the main ink tank to the first sub-ink tank.

[0024] 3. The inkjet recording method according to item 1 or 2, wherein the thermosetting component contains blocked isocyanate.

[0025] 4. An inkjet recording method according to any one of items 1 to 3, further comprising a heating device for heating the flow path of the ink in the second sub-ink tank, and the surface area of the inner wall of the ink tank heated by the heating device in the first sub-ink tank and the second sub-ink tank in contact with the ink is larger in the first sub-ink tank than in the second sub-ink tank.

[0026] 5. The inkjet recording method according to any one of items 1 to 4, wherein a capacity of the first sub-ink tank is larger than a capacity of the second sub-ink tank.

[0027] 6. An inkjet recording device that records an image by ejecting ink from an inkjet head, comprising:

[0028] The main ink tank serves as the ink supply source;

[0029] a first auxiliary ink tank connected to the main ink tank to supply ink;

[0030] a degassing device connected to the first auxiliary ink tank and degassing the ink supplied from the first auxiliary ink tank;

[0031] a second auxiliary ink tank for supplying the ink degassed by the degassing device to the inkjet head and controlling the negative pressure applied to the inkjet head; and

[0032] a heating device for heating at least the ink flow path of the first auxiliary ink tank;

[0033] The ink tank further includes a control unit configured to transport the ink so that an amount of ink newly supplied from the main ink tank to the first sub ink tank is greater than an amount of ink remaining in the first sub ink tank.

[0034] 7. The inkjet recording device according to item 6, wherein the control unit intermittently transports the ink from the main ink tank to the first sub-ink tank.

[0035] According to the above method of the present invention, an inkjet recording method and an inkjet recording apparatus can be provided which have excellent coating film durability and solder heat resistance, and which do not cause ink viscosity increase or polymerization reaction even under ink degassing, and can stably eject ink for a long time.

[0036] The mechanism of effect or action of the present invention is not clear, but is presumed as follows.

[0037] In the ink supply system of an inkjet recording device, it has been found that the most effective way to prevent thermal polymerization of ink after degassing is to keep the ink supplied to the degassing device as fresh as possible. This is presumably because as the ink remains in the first sub-tank for a longer time, the polymerization inhibitor contained in the ink gradually deactivates, making thermal polymerization more likely to occur in the flow path downstream of the degassing device. Therefore, it is best to use up the ink in the first sub-tank all at once, rather than replenishing it over time.

[0038] Therefore, in the present invention, by delivering ink so that the amount of ink newly supplied from the first sub-tank is greater than the amount of ink stored in the first sub-tank, the retention time of the ink in the first sub-tank can be minimized, thereby improving the ink stability of the ink supply system until it is supplied to the inkjet head. Specifically, even under degassing conditions, the ink does not thicken or polymerize, allowing for stable long-term discharge from the inkjet head.

[0039] As a result, the coating film formed by ejecting such ink from the inkjet head shortens the ink residence time in the above-mentioned ink supply system, and as a result, the thermal decomposition of the initiator, thermosetting components, etc. is suppressed, and the efficiency of the original purpose of photocuring and thermal curing after baking is improved, thereby excellent durability.

[0040] Furthermore, since the ink is a radically polymerizable inkjet ink containing a thermosetting component, it is possible to obtain coating film durability and solder heat resistance required for, for example, a solder resist mask. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1A This is a front view illustrating a schematic configuration of an inkjet recording apparatus according to an embodiment of the present invention.

[0042] Figure 1B A top view of an inkjet recording device

[0043] Figure 2 This is a block diagram showing the internal structure of an inkjet recording device.

[0044] Figure 3 This is a diagram illustrating the path of ink in the inkjet recording device of this embodiment.

[0045] Figure 4 It will Figure 3 A partially enlarged view of the ink path is shown.

[0046] Figure 5A This is a top sectional view of the first auxiliary ink tank.

[0047] Figure 5B yes Figure 5A A cross-sectional view along the cutting line VV in the direction of the arrow

[0048] Figure 6A Yes Figure 5B A cross-sectional view of a modified example of

[0049] Figure 6B Yes Figure 5B A top sectional view of a modified example of

[0050] Figure 6C Yes Figure 5B A cross-sectional view of a modified example of

[0051] Figure 7 This is a schematic cross-sectional view of a cylindrical degassing module cut along a plane passing through the central axis.

[0052] Figure 8 This is a flowchart showing an example of the ink supply process. DETAILED DESCRIPTION

[0053] The inkjet recording method of the present invention is an inkjet recording method for recording an image by ejecting ink from an inkjet head, and comprises: a main ink tank as an ink supply source; a first sub-ink tank connected to the above-mentioned main ink tank and supplying ink; a degassing device connected to the above-mentioned first sub-ink tank and degassing the above-mentioned ink supplied from the first sub-ink tank; a second sub-ink tank for supplying the above-mentioned ink degassed by the above-mentioned degassing device to the above-mentioned inkjet head, controlling the negative pressure applied to the inkjet head, and a heating device for heating the flow path of the above-mentioned ink of at least the above-mentioned first sub-ink tank, and further comprising a control unit for conveying the above-mentioned ink in a manner such that the amount of ink newly supplied from the above-mentioned main ink tank to the above-mentioned first sub-ink tank is greater than the amount of ink remaining in the first sub-ink tank, and the above-mentioned ink is a free radical polymerizable ink containing a thermosetting component.

[0054] This feature is a common or corresponding technical feature of the following embodiments.

[0055] As an embodiment of the present invention, it is preferable that the control unit intermittently transports the ink from the main ink tank to the first sub-ink tank, because this can further shorten the retention time in the first sub-ink tank and is effective from the viewpoint of ink stability.

[0056] Furthermore, from the viewpoint of improving the high-temperature and high-humidity resistance of the ink, it is preferred that a blocked isocyanate be contained as the thermosetting component.

[0057] From the viewpoint of improving the heating efficiency of the ink and forming the viscosity most suitable for ejection, it is preferred to further provide a heating device for heating the flow path of the ink in the above-mentioned second sub-ink tank, and the surface area of the inner wall of the ink tank heated by the above-mentioned heating device in the above-mentioned first sub-ink tank and the second sub-ink tank in contact with the above-mentioned ink is larger in the above-mentioned first sub-ink tank than in the above-mentioned second sub-ink tank.

[0058] To facilitate temperature control of the ink in the first sub-tank during high-productivity printing, the capacity of the first sub-tank is preferably larger than that of the second sub-tank. Furthermore, to maintain ink quality after degassing, it is desirable to minimize the time the ink remains in the flow path and sub-tank. Therefore, the capacity of the first sub-tank is preferably larger than that of the second sub-tank.

[0059] Hereinafter, the present invention and its constituent elements and modes and aspects thereof will be described. In the present application, "to" means that the numerical values described before and after it are included as the lower limit and the upper limit.

[0060] [Inkjet recording method of the present invention]

[0061] The following describes in detail an inkjet recording method and an inkjet recording apparatus according to embodiments of the present invention using the accompanying drawings. However, the scope of the invention is not limited to the illustrated examples. It should be noted that in the following description, items having the same functions and configurations are denoted by the same reference numerals, and their descriptions are omitted.

[0062] Figure 1A This is a front view for explaining the schematic structure of the inkjet recording device 1 according to the embodiment of the present invention. Figure 1B It is a plan view of the inkjet recording apparatus 1 .

[0063] The inkjet recording apparatus 1 includes an inkjet head 24 a (discharging operation unit), a UV irradiation unit 72 , a scanning unit 121 , a scanning guide unit 122 , a transport stage 131 , a transport guide unit 132 , and the like.

[0064] The inkjet recording device 1 of this embodiment is, for example, a wiring substrate S (substrate) for ejecting ink. The wiring substrate S is placed on a conveying table 131. The conveying table 131 can move in the direction (conveying direction, sub-scanning direction) of a conveying guide portion 132 such as a guide rail while the wiring substrate S is placed thereon. The wiring substrate S has a conductor (wiring conductor) on a substantially flat plate on an insulating substrate that forms a signal wiring. The conductor is not particularly limited, and may be, for example, copper (copper foil). By making the signal wiring protrude on the surface of the insulating substrate, the wiring substrate S has a stepped portion. In addition, the landed ink does not penetrate into the interior of the wiring substrate S, but bulges on the surface to solidify and fix. It should be noted that here, the surface of the insulating substrate is a plane, and the vertical outward direction relative to the plane is set to the top.

[0065] The inkjet head 24a has nozzles N (see Figure 2), ink is ejected from the nozzle N to the wiring substrate S. The amount of ink ejected to each pixel range in each ink ejection cycle can be selected from a plurality of stages. The UV irradiation unit 72 irradiates ultraviolet light (UV light) to the wiring substrate S where the ink lands. The inkjet head 24a and the UV irradiation unit 72 are fixed to the scanning unit 121, and move (scan) in the direction along the scanning guide 122 (scanning direction. That is, the direction intersecting with the moving direction of the conveyor table 131, which is the orthogonal direction here). These movements can use, for example, a linear motor or the like. The nozzles of the inkjet head 24a are arranged across the width of the wiring substrate S, and the arrangement interval of the nozzles is set to be small enough so that printing (single channel) can be completed with one scan. In addition, by moving the wiring substrate S while repeating multiple scans of the return inkjet head 24a, multiple channels (interlaced) of ink ejection can be performed.

[0066] Figure 2 It is a block diagram showing the functional configuration of the inkjet recording apparatus 1 .

[0067] The inkjet recording device 1 includes a transport unit 10, an inkjet head 24a (ink ejection unit), a head drive control unit 30, a fixing unit 70, a control unit 40, a storage unit 60, an ink heating unit (heating device) 270, a display unit 81, an operation receiving unit 82, a communication unit 90, a liquid feeding pump 243, a supply pump 53, a vacuum pump 249, a circulation pump 246, a float sensor 241a, a sensor 2427, a float sensor 245a, and the like. The control unit 40 is communicatively connected to each of these units via a bus or the like.

[0068] The transport unit 10 moves the inkjet head 24a relative to the medium on which the image (film) is to be formed, in this case, the wiring substrate S. As described above, for example, the inkjet head 24a can move in a predetermined direction (scanning direction) relative to the wiring substrate S, and the wiring substrate S can move in a direction perpendicular to the scanning direction of the inkjet head 24a.

[0069] The transport unit 10 includes a scanning drive unit 12 and a transport drive unit 13. The scanning drive unit 12 performs scanning by moving the inkjet head 24a along the scanning unit 121. The scanning drive unit 12 includes, for example, a linear motor and moves the inkjet head 24a directly or indirectly via a fixing member of the inkjet head 24a.

[0070] The transport drive unit 13 moves a placing member such as a base (transport stage 131 ) or a conveyor belt on which the wiring substrate S is placed. The transport drive unit 13 can reciprocate the placing member.

[0071] The inkjet head 24a includes a nozzle drive unit 22 and a plurality of nozzles N. Ink is ejected from the nozzles N in response to a drive signal output by the nozzle drive unit 22. The nozzle drive unit 22 includes, for example, an ejection selection IC 28 (Integrated Circuit) and an electromechanical conversion element 223. The ejection selection IC 28 switches the operation based on image data so that a drive signal corresponding to the presence or absence of ink ejection and the amount of ink ejected from each nozzle N is output to the electromechanical conversion element 223 corresponding to each nozzle N. The electromechanical conversion element 223 is, for example, a piezoelectric element, and generates a shape change corresponding to the input drive signal. This shape change causes a pressure change in the ink in the ink flow path connected to the nozzle N.

[0072] The electromechanical conversion element 223 and the nozzle N constitute a recording element 26 .

[0073] The nozzle drive control unit 30 includes a nozzle control unit 31 and a drive waveform signal generation circuit 32. Based on the output data (digital data) of the drive waveform signal generation circuit 32, the drive waveform signal (analog signal) related to ink ejection, etc., is output to the inkjet head 24a at a predetermined time period (ink ejection period). The drive waveform signal related to ink ejection can be a combination of multiple pulse signals. Alternatively, a drive waveform signal having multiple different waveform patterns (including not only waveforms but also changes in pulse length, amplitude, and voltage value) can be output in accordance with the amount of ink ejected. Alternatively, a number of continuous drive pulses corresponding to the amount of ink droplets per pixel (multi-pulse method) can be output. In this case, the ink droplets ejected by each drive pulse are caused to aggregate in flight or land within the same pixel range. The ink ejected from each nozzle in one path (one cycle) to each pixel can be set to a minimum thickness (e.g., 15 μm) for the insulating film described later, taking into account the surface properties of the wiring substrate S, the temperature (viscosity) of the ink during ejection, and the time interval from the landing of the ink droplets to their temporary fixation by UV light irradiation from the UV irradiation unit 72. Furthermore, not only when ejecting ink, but also when a non-ejection waveform pattern is output to agitate the ink within the nozzle N can be used.

[0074] In addition to or in lieu of the above methods, the ink ejection volume (landing amount) per pixel can be controlled using other methods, such as adjusting the ink pressure (typically to a negative pressure to prevent ink leakage) in the absence of a drive pulse, thereby adjusting the state of the ink liquid surface (meniscus) within the nozzle N, or by varying the drive frequency. Furthermore, the ink droplet volume can be adjusted by applying a drive pulse with a drive waveform pattern while vibrating the meniscus by pre-applying a drive pulse with a suitable non-ejection waveform pattern prior to the ink ejection waveform pattern.

[0075] The fixing unit 70 performs the action of fixing the ink landed on the wiring substrate S. As will be described later, the ink of the present invention has curing properties based on thermosetting and active energy rays (UV light), so correspondingly, the fixing unit 70 includes a UV irradiation unit 72 and a heating fixing unit 73. Without particular limitation, here, the UV irradiation unit 27 is fixed to the scanning unit 121 together with the inkjet head 24a as described above to perform scanning, so that the ink landed on the wiring substrate S is temporarily fixed. The UV irradiation unit 27 irradiates ultraviolet light (UV light) by, for example, having a light emitting diode (LED) that emits ultraviolet light, applying voltage to the LED and passing current to cause it to emit light. The UV irradiation unit 72 may be provided with a light-shielding wall or the like for shielding the UV light from leaking out of the desired irradiation range as needed.

[0076] It should be noted that the configuration for emitting UV light in the UV irradiation unit 72 is not limited to LEDs. The UV irradiation unit 72 may include, for example, a mercury lamp. Furthermore, if the ink has the property of being cured and fixed by active energy rays other than UV light, the UV irradiation unit 72 may include a known emission source (light source) that emits active energy rays that cure the ink, rather than the configuration for emitting UV light.

[0077] The heating and fixing section 73 has a heating section such as an infrared heater or an electric wire heater, which directly or indirectly heats the wiring substrate S to permanently fix the temporarily fixed ink. The heating and fixing section 73 is located after the ink is landed and temporarily fixed by the inkjet head 24a and the UV irradiation section 72, for example, after the wiring substrate S is transported to the downstream side in the transport direction, where it is permanently fixed. The heating and fixing section 73 can be set in a shell that surrounds the wiring substrate S and the conveying component that carries the wiring substrate S, so that the heat generated by the heating section is maintained inside the shell at an appropriate curing temperature with high efficiency. In this case, it is not necessary to keep the heating section in operation during heating, and it is sufficient to maintain the temperature within the set range of the above-mentioned curing temperature.

[0078] It should be noted that the inkjet recording apparatus 1 does not need to include the heating and fixing unit 73, but may include the heating and fixing unit 73 in a separate heating and fixing unit. Furthermore, the heating and fixing unit is a post-processing unit of the inkjet recording apparatus 1. The transport unit 10 may directly transport the wiring substrate S to the heating and fixing unit located, for example, on an extension of the direction of movement of the transport table 131. Alternatively, the transport unit 10 may be configured to directly transport the wiring substrate S removed from the transport table 131 of the inkjet recording apparatus 1 and then mounted on the heating and fixing unit. Alternatively, the user may manually transport the wiring substrate S.

[0079] The control unit 40 centrally controls the operations of various components of the inkjet recording device 1. The control unit 40 includes a CPU 41 (Central Processing Unit) and a RAM 42 (Random Access Memory). The CPU 41 is a hardware processor that performs various calculations and executes programs 61 stored in the storage unit 60. The RAM 42 provides control memory for the CPU 41 and stores temporary data.

[0080] Specifically, the control unit 40 performs the following processing on the inkjet recording apparatus 1 .

[0081] Specifically, based on detection data from a float sensor 241a provided in the first sub-tank 241, described later, the control unit 40 operates the supply pump 53 and valve 55 to supply ink from the main ink tank 51 to the first sub-tank 241, such that the amount newly supplied from the main ink tank 51 to the first sub-tank 241 (the supply amount) is greater than the amount of ink stored in the first sub-tank 241 (the remaining amount). In this manner, the control unit 40 intermittently supplies ink from the main ink tank 51 to the first sub-tank 241. Details will be provided later.

[0082] The storage unit 60 includes at least a nonvolatile memory and stores the program 61 and setting data. As an example of the nonvolatile memory, a flash memory can be cited. In addition, the nonvolatile memory mentioned here can also include an HDD (Hard Disk Drive) and the like.

[0083] The ink heating unit 270 heats and maintains the ink at an appropriate temperature within the inkjet head 24a and the ink supply path to the inkjet head 24a. As will be described later, ink undergoes a phase transition between sol and gel depending on the temperature. Therefore, in a gel state at room temperature, the ink's fluidity is insufficient, making it difficult to supply and eject the ink. By heating the ink to an appropriate temperature, the ink heating unit 270 maintains the ink in a sol state, enabling proper supply and ejection. The appropriate temperature can be determined so that after the ink lands on the wiring substrate S, it dissipates heat rapidly through the wiring substrate S, resulting in gelation at an appropriate time.

[0084] As will be described later, the ink heating unit 270 may be, for example, a heating wire or a rubber heater. When electricity is supplied to the heating wire or the rubber heater, the heating wire or the rubber heater contacts the ink flow path and transfers heat to heat the ink.

[0085] The display unit 81 displays various statuses, menus, and the like on a display screen under the control of the control unit 40. The display unit 81 includes, for example, a display screen and LEDs (Light Emitting Diodes). Unless otherwise specified, the display screen is, for example, an LCD (Liquid Crystal Display). The LEDs are illuminated (including flashing) by the control unit 40 in positions and colors corresponding to the power supply status, abnormality occurrence, and other conditions.

[0086] The operation receiving unit 82 receives input operations from an external user, etc., and outputs them as input signals to the control unit 40. The operation receiving unit 82 includes, for example, a touch panel and push buttons. The touch panel may be located at a position overlapping the display screen of the display unit 81. In addition, the operation receiving unit 82 may include various other operation switches.

[0087] The communication unit 90 controls the transmission and reception of data (signals) with external devices, etc., according to a predetermined communication standard. For example, the communication unit 90 controls communication according to the LAN (Local Area Network) standard. Alternatively, the communication unit 90 can connect to peripheral devices, etc., using the USB (Universal Serial Bus) standard.

[0088] Figure 3 : is an explanatory diagram for explaining the path of ink in the inkjet recording apparatus 1 of this embodiment. Figure 4 This is a diagram showing a part of the ink path in an enlarged manner.

[0089] In the inkjet recording device 1 of this embodiment, ink pumped from a main ink tank 51 serving as an ink supply source 50 by a supply pump 53 is supplied to each inkjet head 24a via a valve (e.g., a solenoid valve) 55 and an ink path 24b. Furthermore, the device is configured so that ink not ejected from each inkjet head 24a can be returned to the ink path 24b.

[0090] The ink path 24b includes a first sub-ink tank 241, a filter 241d, a degassing module 242, a liquid feeding pump 243, a check valve 244, a second sub-ink tank 245, a filter 245c, etc. These are not particularly limited and are connected by, for example, a hollow annular pipe structure.

[0091] In addition, it is preferable to provide a circulation pump 246 in parallel with the degassing module 242 so as to return the ink flowing out of the degassing module 242 to the ink inlet 2422 of the degassing module 242 via the circulation path 24c connected to both ends of the degassing module 242 (see Figure 7 ) is nearby.

[0092] The inkjet head 24a, ink path 24b, and circulation path 24c are heated and kept warm by an ink heating unit 270 such as a heater or a heat-conducting member that transfers heat from the heater, so that the temperature of the ink is maintained at an appropriate temperature.

[0093] As the heater of the ink heating unit 270, for example, a rubber heater 272 or a heating wire 271 (see Figure 4 ), generates heat by passing electricity.

[0094] As the heat conducting member, it is preferable to use a member having high thermal conductivity, for example, a heat conducting plate formed of various metals (alloys), and to provide the heat conducting member so as to cover the piping of the ink path 24 b and the circulation path 24 c .

[0095] The check valve 247 , the trap 248 , the vacuum pump (degassing pump) 249 and the like are connected in series with the degassing module 242 to constitute a degassing device.

[0096] The ink in the main ink tank 51 of the ink supply source 50 is maintained at room temperature (25° C.).

[0097] <First ink tank>

[0098] The first sub-ink tank 241 is one or more ink chambers that store ink drawn from the main ink tank 51 by the supply pump 53 and the valve 55 .

[0099] It is preferable that the capacity of the first sub-ink tank 241 is smaller than the capacity of the main ink tank 51 and larger than the capacity of the second sub-ink tank 245 described later.

[0100] Specifically, the capacity of the first sub-tank 241 also varies depending on the number of inkjet heads mounted and the design, but is preferably larger than the capacity of the second sub-tank 245 within a range of 1.1 times or more and less than 2.0 times.

[0101] The surface area of the inner wall of the first and second sub-tanks 241 and 245 heated by the ink heating unit 270 that is in contact with the ink (also referred to as "liquid contact surface area") is preferably larger in the first sub-tank 241 than in the second sub-tank 245. Specifically, it is preferably larger in the first sub-tank 241 than in the second sub-tank 245, within a range of 1.1 times or more and less than 5.0 times.

[0102] Here, for example Figure 4 、 Figure 5A and Figure 5BAs shown in the figure, "the surface area of the inner wall of the ink tank heated by the ink heating unit 270 in the first auxiliary ink tank 241 that is in contact with the ink (the liquid contact surface area)" refers to the surface area of the ink that is in contact with the inner surface of the side wall 2411 and the bottom 2412 of the first auxiliary ink tank 241 when the rubber heater 272 is provided on the outer surface (outer wall surface) of the side wall 2411 and the bottom 2412 of the first auxiliary ink tank 241, and heat is transferred to the ink in the ink tank through the side wall 2411 and the bottom 2412 heated by the rubber heater 272. In addition, in this case, it is not the case that Figure 5A and Figure 5B As shown, in addition to the rubber heater 272 provided on the outer surfaces of the side wall portion 2411 and the bottom portion 2412 of the first sub-ink tank 241, a partition 2415 is provided in the first sub-ink tank 241. When heat is transferred to the ink in the ink tank via the partition 2415 heated by the rubber heater 272, the surface area where the ink contacts the surface of the partition 2415 is also included.

[0103] It should be noted that the second sub-ink tank 245 also has the same definition as above.

[0104] In addition, the "inner wall of the ink tank" refers to, for example, the side wall portion 2411 of the first sub-ink tank 241, the inner surface of the bottom 2412, and the surface of the partition 2415 arranged in the first sub-ink tank 241. In the case of the second sub-ink tank 245, it has the same definition as above.

[0105] In order to increase the liquid receiving surface area of the first auxiliary ink tank 241, the first auxiliary ink tank 241 is as follows. Figure 5A and Figure 5B As shown, it is preferred that a partition 2415 is provided on the outer surface of the side wall portion 2411 of the first auxiliary ink tank 241 , the outer surface of the bottom 2412 , and inside the first auxiliary ink tank 241 .

[0106] Hereinafter, the arrangement pattern of the ink heating portion 270 and the partition plate 2415 provided in the first sub-ink tank 241 will be described.

[0107] FIG5 is a schematic diagram showing the first auxiliary ink tank, Figure 5A It is a top cross-sectional view. Figure 5B yes Figure 5A A cross-sectional view taken along the cutting line VV in the direction of the arrow.

[0108] The first auxiliary ink tank 241 is provided with a rubber heater 272 as an ink heating unit 270 on the outer surfaces of the sidewall 2411 and bottom 2412. Furthermore, within the first auxiliary ink tank 241, a partition 2415 is arranged in a generally rectangular shape, spiraling counterclockwise from the left sidewall 2411 toward the center when viewed from above, thereby forming an ink flow path. The partition 2415 is thermally conductively connected to the rubber heater 272.

[0109] In addition, an inlet 2413 into which ink supplied from the main ink tank 51 flows is provided on the left side wall portion 2411 of the first sub-ink tank 241 , and the inlet 2413 communicates with the ink flow path.

[0110] In addition, an outflow port 2414 connected to the degassing module (degassing device) 242 is provided at the most downstream position of the ink flow path in the first sub-ink tank 241, that is, near the central part of the first sub-ink tank 241. The ink flowing in from the inflow port 2413 flows counterclockwise along the ink flow path in the first sub-ink tank 241 and is transported to the degassing module 242 via the outflow port 2414.

[0111] In addition, a float sensor 241a is provided as a liquid level sensor in the first auxiliary ink tank 241. The location of the float sensor 241a is not particularly limited, but it is preferably provided at the most downstream location of the ink flow path of the first auxiliary ink tank 241. Figure 5A It is arranged near the center of the first auxiliary ink tank 241.

[0112] It should be noted that the arrangement pattern of the partition 2415 in the first auxiliary ink tank 241 is not limited to Figure 5A and Figure 5B , for example, Figures 6A to 6C The configuration pattern shown.

[0113] Figures 6A to 6C Yes Figure 5A and Figure 5B An upper sectional view of the first sub-ink tank of a modified example.

[0114] Figure 6A In the illustrated first sub-ink tank 241 , a plurality of partitions 2415 are alternately provided between the left and right sidewalls 2411 and 2411 facing each other. Thus, a serpentine ink flow path is formed in the first sub-ink tank 241 .

[0115] An outflow port 2414 communicating with the degassing module 242 is provided at the most downstream position of the ink flow path in the first sub-ink tank 241 . The ink flowing in from the inflow port 2413 flows in a serpentine manner through the ink flow path in the first sub-ink tank 241 and is transported to the degassing module 242 via the outflow port 2414 .

[0116] In addition, a float sensor 241 a is provided near the degassing module 242 of the first sub-ink tank 241 .

[0117] It should be noted that a rubber heater 272 is provided on the outer surfaces of the side wall portion 2411 and the bottom portion 2412 of the first sub-ink tank 241 .

[0118] Figure 6BThe first auxiliary ink tank 241 shown has a partition plate 2415 disposed in the center of the first auxiliary ink tank 241, substantially parallel to the left and right sidewalls 2411 and 2411, to divide the interior of the first auxiliary ink tank 241 into left and right spaces. This partitions the interior of the first auxiliary ink tank 241 into two spaces, forming a flow path for ink.

[0119] In the space on the right side of the first sub-ink tank 241 , an outlet 2414 connected to the degassing module 242 is provided. The ink flowing in from the inlet 2413 flows from the left side to the right side of the first sub-ink tank 241 and is transported to the degassing module 242 through the outlet 2414 .

[0120] In addition, a float sensor 241 a is provided near the degassing module 24 of the first sub-ink tank 241 .

[0121] It should be noted that a rubber heater 272 is provided on the outer surfaces of the side wall portion 2411 and the bottom portion 2412 of the first sub-ink tank 241 .

[0122] Figure 6C The first sub-ink tank 241 shown has a partition 2415 provided in a cross shape in a plan view at the center of the first sub-ink tank 241. Thus, clockwise and counterclockwise ink flow paths are formed in the first sub-ink tank 241.

[0123] At the most downstream position of the ink flow path in the first sub-ink tank 241, an outflow port 2414 connected to the degassing module 242 is provided. The ink flowing in from the inflow port 2413 flows clockwise or counterclockwise through the ink flow path in the first sub-ink tank 241 and is transported to the degassing module 242 via the outflow port 2414.

[0124] In addition, a float sensor 241 a is provided near the degassing module 242 of the first sub-ink tank 241 .

[0125] It should be noted that a rubber heater 272 is provided on the outer surfaces of the side wall portion 2411 and the bottom portion 2412 of the first sub-ink tank 241 .

[0126] Should be explained, such as Figure 6A 、 Figure 6B and Figures 6A to 6C The first sub-ink tank 241 shown is an example of an embodiment of the present invention, and the present invention is not limited thereto.

[0127] For example Figure 5A 、 Figure 5B as well as Figures 6A to 6CThe illustrated first sub-ink tank 241 has a rubber heater 272 provided on the outer surfaces of the sidewalls 2411 and bottom 2412. However, the rubber heater 272 may be provided on the inner surfaces of the sidewalls 2411 and bottom 2412. In this case, from the perspective of durability, it is preferable to cover the surface of the rubber heater 272 with another member to prevent direct contact between the rubber heater 272 and the ink.

[0128] in addition, Figure 5A 、 Figure 5B and Figures 6A to 6C The first sub-ink tank 241 shown is configured such that a partition 2415 is provided inside the first sub-ink tank 241 and is thermally conductively connected to a rubber heater 272 provided on the outside of the first sub-ink tank 241 via the partition 2415. However, the present invention is not limited thereto and a rubber heater may be provided inside two partitions (not shown).

[0129] In addition, as the flow path components after the first sub-ink tank 241 and the partition plate 2415, it is preferable to use a metal with high thermal conductivity, such as aluminum or copper. From the perspective of cost and processability, aluminum is more preferable.

[0130] The float sensor 241a provided in the first sub-ink tank 241 detects the ink liquid level. The control unit 40 opens and closes the valve 57 and operates the supply pump 53 based on the liquid level detection data from the float sensor 241a.

[0131] Specifically, the control unit 40 operates the valve 55 and the supply pump 53 based on the detection data from the float sensor 241a, so that the amount of ink newly supplied from the main ink tank 51 to the first sub-tank 241 is greater than the amount of ink stored (remaining) in the first sub-tank 241. This shortens the retention time of the ink in the first sub-tank 241.

[0132] It should be noted that as a liquid level sensor, in addition to the above-mentioned float sensor 241a that detects the liquid level by the position of the float, an ultrasonic sensor that measures the reflection of ultrasonic waves on the liquid surface, a dielectric constant capacitive sensor that detects the liquid level by the difference in dielectric constant between gas and liquid, and a pressure sensor that detects the weight and pressure of the liquid at the bottom of the ink tank can be used.

[0133] Degassing module

[0134] The degassing module 242 performs a degassing process to remove gases such as air from the inflowing ink, and discharges the degassed ink.

[0135] The degassing module 242 can generally reduce the air concentration in the ink to a level that does not adversely affect ink ejection through a single degassing operation. However, the air concentration can be further reduced by performing degassing operations multiple times.

[0136] Figure 7 This is a schematic cross-sectional view taken along a plane passing through the central axis of the cylindrical degassing module 242 .

[0137] The degassing module 242 is configured such that multiple hollow membranes (permeable components) 2426 surround a central tube 2424 within a housing 2421. One end of the central tube 2424 is connected to an ink inlet 2422, and the other end is sealed with a plug 2424a. Numerous fine holes 2424b (perforations) are provided on the outer wall of the central tube 2424. Ink flowing into the central tube 2424 from the ink inlet 2422 flows out through these fine holes 2424b, passes through the hollow membranes 2426, and exits through the ink outlet 2423. An ink flow path 2428 is formed by the ink inlet 2422, the interior of the central tube 2424, the outer side of the central tube 2424 and between the multiple hollow membranes 2426, and the ink outlet 2423.

[0138] The hollow membrane 2426 comprises multiple hollow microstructures with one end closed, and its membrane surface is gas-permeable. The other end of the microstructures of the hollow membrane 2426 is connected to the gas outlet 2425. A vacuum pump 249 is used to draw air from the microstructures, reducing the pressure inside the hollow membrane 2426. In this state, the ink contacts the membrane surface of the hollow membrane 2426, allowing only gases such as air in the ink to selectively permeate the membrane surface, degassing the ink. The interior of the microstructures of the hollow membrane 2426, the gas outlet 2425, and other components form a gas flow path 2429.

[0139] From the perspective of degassing efficiency and processing flow rate, it is preferred that the above-mentioned degassing module 242 is an external reflux type hollow membrane degassing module in which the ink is degassed on the inner side of the hollow membrane 2426 and flows on the outer side of the hollow membrane 2426, but other methods such as internal reflux type can also be used.

[0140] Furthermore, it is preferable to provide a sensor 2427 for detecting whether the ink flow path 2428 is filled with ink in the degassing module 242 at a position least likely to be reached by the ink flowing in from the ink inlet 2422 .

[0141] The location in the ink flow path 2428 that is most difficult for ink to reach is a location where, if ink reaches this location, the entire area of the ink flow path 2428 is filled with ink. Examples of this location include the base ends of the plurality of hollow membranes 2426, the location farthest from the ink inlet 2422, and the location farthest from the ink outlet 2423. When ink reaches the location where the sensor 2427 is provided, the detection result is output to the control unit 40.

[0142] The liquid feeding pump 243 feeds the ink flowing out of the ink outlet 2423 of the degassing module 242 to the second sub-ink tank 245. A check valve 244 is provided between the liquid feeding pump 243 and the second sub-ink tank 245 to prevent the ink fed to the second sub-ink tank 245 from flowing back.

[0143] It should be noted that the liquid feeding pump 243 is disposed between the degassing module 242 and the second sub-ink tank 245 , but is not limited thereto. The liquid feeding pump 243 may also be disposed between the first sub-ink tank 241 and the degassing module 242 .

[0144] Second ink tank

[0145] The second sub-ink tank 245 is a small ink chamber that temporarily stores the ink degassed by the degassing module 242 , and preferably has a smaller capacity than the first sub-ink tank 241 .

[0146] Furthermore, the surface area of the inner wall heated by the ink heating unit 270 in the second sub-ink tank 245 that contacts the ink (liquid contact surface area) is preferably smaller in the second sub-ink tank 245 than in the first sub-ink tank 241 .

[0147] In order to reduce the liquid contact surface area of the second auxiliary ink tank 245, the second auxiliary ink tank 245 is not provided with a partition 2415 as in the first auxiliary ink tank 241, but is preferably provided with a rubber heater 272 only on the outer surface of the side wall or bottom of the second auxiliary ink tank 245 (see Figure 4 ).

[0148] The second sub-ink tank 245 is connected to the inlet 240 a of each inkjet head 24 a , and ink corresponding to the amount of ink ejected from the nozzle is supplied from the second sub-ink tank 245 to each inkjet head 24 a .

[0149] The second sub-ink tank 245 is provided with a float sensor 245 a . Based on the detection data of the liquid level position by the float sensor 245 a , the control unit 40 operates the liquid feed pump 243 to store a predetermined amount of ink.

[0150] Furthermore, a float sensor 245b is provided in the second auxiliary ink tank 245, covering the surface of the degassed ink. Since the second auxiliary ink tank 245 is open to the atmosphere, the float sensor 245b reduces the contact area between the atmosphere and the degassed ink, thereby preventing re-introduction of air into the ink. It should be noted that in industrial inkjet recording devices 1, degassed ink, for example, during continuous image formation, is not retained in the second auxiliary ink tank 245 for extended periods of time, often resulting in minimal re-introduction of air. Therefore, the second auxiliary ink tank 245 may be configured to include the float sensor 245b.

[0151] Ink that is not ejected from the nozzles of the inkjet head 24a can be returned from the ejection port 240b via the recovery path 241b and the valve 241c to the first sub-ink tank 241. When it is necessary to remove ink from the inkjet head 24a during maintenance of the inkjet head 24a, the ink in the inkjet head 24a can be recovered without waste by opening the valve 241c.

[0152] A trap 248 is provided between the degassing module 242 and the vacuum pump 249 via a check valve 247. The hollow membrane 2426 is normally impermeable to liquid ink, but depending on the degree of negative pressure applied by the vacuum pump 249, a small amount of ink may penetrate. This permeated ink, which deteriorates before reaching the vacuum pump 249, is collected by the trap 248. The ink collected by the trap 248 can be removed by opening a valve (not shown) connected to the trap 248.

[0153] Here, as described above, the ink in the ink path 24b is heated and kept warm by the ink heating unit 270. The temperature is preferably within a range of 70 to 80°C, for example.

[0154] In particular, in this embodiment, a rubber heater 272 is provided in the first sub-ink tank 241. This rubber heater 272 allows the ink fed from the main ink tank 51 to be heated to a predetermined temperature before being delivered to the degassing module 242. In the case of gel ink, heating is particularly necessary to completely dissolve the ink.

[0155] Furthermore, the degassing module 242 is provided with a heating wire 271. Since heat from the heater, heat conducting plate, etc. covering the outside is difficult to transfer to the interior of the degassing module 242, by preheating the module 242 separately in this way and transferring the heat to the interior, the ink can be heated more effectively inside the degassing module 242, where the ink has a longer residence time, than in the ink path 24b, which is longer than normal.

[0156] Furthermore, in the inkjet recording device 1 of this embodiment, when the ink supply to the inkjet head 24a is stopped, the circulation pump 246 appropriately circulates the ink within the degassing module 242, thereby heating and maintaining the entire ink flowing through the degassing module 242 and the circulation path 24c in a suitable and well-balanced manner. Furthermore, even when the ink cools, such as when the inkjet recording device 1 is powered on, the ink can be quickly heated, circulated, and ejected at a suitable temperature.

[0157] Next, refer to the following Figure 8 An example of the ink supply process performed by the control unit 40 in the inkjet recording apparatus 1 configured as described above will be described. Figure 8 This is a flowchart showing an example of the ink supply process.

[0158] First, the control unit 40 determines whether the float sensor 241 a in the first sub-tank 241 has detected a lower limit value of the amount of ink stored in the first sub-tank 241 (remaining ink amount) (step S1 ).

[0159] When the above-mentioned ink remaining amount judgment does not detect the lower limit value (step S1; NO), the valve 55 between the main ink tank 51 and the first sub-ink tank 241 is closed (step S5), and the ink is stopped from being transported from the main ink tank 51 to the first sub-ink tank 241 (step S6).

[0160] When it is determined that the remaining ink level has reached the lower limit (step S1 ; YES), the control unit 40 opens the valve 55 between the main ink tank 51 and the first sub-ink tank 241 (step S2 ).

[0161] Next, the control unit 40 uses the supply pump 53 to deliver ink from the main ink tank 51 to the first sub-tank 241 (step S3). Furthermore, the float sensor 241a in the first sub-tank 241 detects the upper limit of the remaining ink level in the first sub-tank 241 to determine whether the ink level is sufficient (step S4).

[0162] When it is determined that the remaining amount of ink in the first sub-ink tank 241 has not reached the upper limit (step S4 ; NO), the ink is continuously fed by the supply pump 53 (step S3 ).

[0163] When it is determined that the remaining ink amount in the first sub-ink tank 241 is the upper limit value (step S4; YES), the control unit 40 closes the valve 55 between the main ink tank 51 and the first sub-ink tank 241 (step S5), and stops supplying ink from the main ink tank 51 to the first sub-ink tank 241 (step S6).

[0164] In this way, the control unit 40 usually controls the operation of the valve 55 and the supply pump 53 based on the detection result of the float sensor 241a of the first sub-ink tank 241, intermittently delivers ink, so that the amount of new ink supplied to the first sub-ink tank 241 is greater than the amount of ink stored in the first sub-ink tank 241.

[0165] <Ink>

[0166] The ink used in the inkjet recording method of the present invention is a radical polymerization type inkjet ink containing a thermosetting component, that is, a compound having a thermosetting functional group.

[0167] The ink of the present invention preferably contains a gelling agent to undergo a sol-gel phase transition depending on temperature. Furthermore, the ink of the present invention preferably contains a compound having a photopolymerizable functional group and a photopolymerization initiator.

[0168] It should be noted that the ink of the present invention is not limited to the above-mentioned neutral ink, and may be a water-based ink or an ink having other physical properties.

[0169] (1) Compounds with thermosetting functional groups

[0170] Examples of the thermosetting functional group of the present invention include those cited in general articles such as "Precision of Thermosetting Polymers" (Tsuyoshi Endo, CMC Co., Ltd., 1986) and "Latest Adhesive Technology Handbook," Chapter II-I (Yuji Harazaki, General Technology Center, 1985), "Synthesis, Design, and New Application Development of Acrylic Resins" (Takayuki Otsu, Chubu Business Development Center Publishing Department, 1985), and "Functional Acrylic Resins" (Eizo Omori, Techno Systems, 1985). Specifically, from the perspective of thermosetting properties, the thermosetting functional group is preferably at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an isocyanate group, an epoxy group, a (meth)acryloyl group, a maleimide group, a mercapto group, and an alkoxy group.

[0171] (Hydroxy)

[0172] Examples of the compound having a hydroxyl group include various hydroxyl-containing (meth)acrylates (e.g., 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, etc.), addition reaction products of the above various hydroxyl-containing (meth)acrylates and ε-caprolactone, various hydroxyl-containing vinyl ethers (e.g., 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 3-hydroxybutyl vinyl ether, etc.), ether, 2-hydroxy-2-methylpropyl vinyl ether, 5-hydroxypentyl vinyl ether, 6-hydroxyhexyl vinyl ether, etc.), addition reaction products of the above various hydroxyl-containing vinyl ethers and ε-caprolactone, various hydroxyl-containing allyl ethers (for example, 2-hydroxyethyl (methyl) allyl ether, 3-hydroxypropyl (methyl) allyl ether, 2-hydroxypropyl (methyl) allyl ether, 4-hydroxybutyl (methyl) allyl ether, 3-hydroxybutyl (methyl) allyl ether, 2-hydroxy-2-methylpropyl (methyl) allyl ether, 5-hydroxypentyl (methyl) allyl ether, 6-hydroxyhexyl (methyl) allyl ether, etc.), addition reaction products of the above various hydroxyl-containing allyl ethers and ε-caprolactone, etc.

[0173] (carboxyl)

[0174] Examples of the compound having a carboxyl group include various carboxyl group-containing monomers (e.g., (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, etc.), various α,β-unsaturated dicarboxylic acids and monoesters of monohydric alcohols having 1 to 18 carbon atoms (e.g., monomethyl fumarate, monoethyl fumarate, monobutyl fumarate, monoisobutyl fumarate, monotert-butyl fumarate, monohexyl fumarate, monooctyl fumarate, fumaric acid monoesters), and monoethyl fumarate. 2-ethylhexyl maleate, monomethyl maleate, monoethyl maleate, monobutyl maleate, monoisobutyl maleate, monotert-butyl maleate, monohexyl maleate, monooctyl maleate, mono-2-ethylhexyl maleate, etc.), monoalkyl itaconate (for example, monomethyl itaconate, monoethyl itaconate, monobutyl itaconate, monoisobutyl itaconate, monohexyl itaconate, monooctyl itaconate, mono-2-ethylhexyl itaconate, etc.), etc.

[0175] In addition, carboxyl group-containing acrylate compounds can be mentioned, which can be obtained by copolymerizing unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid and their anhydrides with acrylic acid monomers. Among the unsaturated carboxylic acids, acrylic acid and methacrylic acid are preferably used. Examples of acrylic monomers that constitute the carboxylic acid group-containing acrylic copolymer include isoamyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, isononyl (meth)acrylate, isomyristyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, N-hydroxymethyl (meth)acrylic acid amide, glycidyl (meth)acrylate, (meth)acrylic acid amide, N,N-dimethyl (meth)acrylic acid amide, N,N-diethyl (meth)acrylic acid amide, (meth)acryloylmorpholine, (meth)acetonitrile, vinylpyrrolidone, N-cyclohexylmaleimide, itaconimide, and N,N-dimethylaminoethyl (meth)acrylic acid amide. Furthermore, vinyl acetate and styrene may also be used. These monomers may be used alone or in combination of two or more.

[0176] (isocyanate group)

[0177] The compound having an isocyanate group is not particularly limited as long as it has two or more isocyanate groups in the molecule, and specific examples include 2,4-toluene diisocyanate (2,4-TDI), 2,6-toluene diisocyanate (2,6-TDI), 4,4′-diphenylmethane diisocyanate (4,4′-MDI), 2,4′-diphenylmethane diisocyanate (2,4′-MDI), 1,4-phenylene diisocyanate, xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), dimethylbiphenyl diisocyanate (TODI), 1,5-naphthalene diisocyanate, and 1,5-naphthalene diisocyanate. Aromatic polyisocyanates such as nonanodized diisocyanate (NDI); aliphatic polyisocyanates such as hexamethylene diisocyanate (HDI), trimethylhexamethylene diisocyanate (TMHDI), lysine diisocyanate, norbornane diisocyanate methyl ester (NBDI); alicyclic polyisocyanates such as trans-cyclohexane-1,4-diisocyanate, isophorone diisocyanate (IPDI), H6XDI (hydrogenated XDI), H12MDI (hydrogenated MDI), H6TDI (hydrogenated TDI); polyisocyanates such as polymethylene polyphenylene polyisocyanate; their biuret products, isocyanurate products and carbodiimide-modified products, etc.

[0178] As the acrylate or methacrylate compound having an isocyanate group, any one having an isocyanate group and an acryloyl group or a methacryloyl group in the molecule may be used, and reaction products of hydroxyalkyl acrylates such as hydroxyethyl acrylate or methacrylate with polyisocyanates such as toluene diisocyanate, etc., may be used.

[0179] Among the above-mentioned compounds having an isocyanate group, polyfunctional isocyanate compounds having an isocyanate group protected by a thermally dissociable blocking agent (blocked isocyanate group) are preferred from the viewpoint of improving resistance to high temperature and high humidity.

[0180] In the case of a polyfunctional isocyanate compound having an isocyanate group protected by a blocking agent, the isocyanurate ring bond generated by the trimerization reaction of the isocyanate has higher thermal stability and excellent heat resistance than urethane or urea bonds. Furthermore, when a polyfunctional isocyanate compound is used, a network structure having an isocyanurate ring is further formed, which further improves the heat resistance and makes it less susceptible to the influence of humidity at high temperatures.

[0181] From the perspective of ink storage stability and thermal dissociation properties, the thermally dissociable blocking agent is preferably at least one compound selected from the group consisting of oxime compounds, pyrazole compounds, and active vinyl compounds.

[0182] Examples of the oxime compound include formamide oxime, acetaldehyde oxime, acetone oxime, methyl ethyl ketone oxime, and cyclohexanone oxime.

[0183] Examples of the pyrazole compound include pyrazole, 3-methylpyrazole, and 3,5-dimethylpyrazole.

[0184] Examples of the active vinyl compound include dimethyl malonate, diethyl malonate, methyl acetoacetate, ethyl acetoacetate, and acetylacetone.

[0185] Examples of the polyfunctional isocyanate compound having an isocyanate group protected by the blocking agent include ethyl 2-[(3,5-dimethylpyrazolyl)carbonylamino]methacrylate, ethyl 2-[(3-butylene)aminooxycarbonylamino]methacrylate, ethyl 2-[(3,5-dimethylpyrazolyl)carbonylamino]acrylate, and ethyl 2-[(3-butylene)aminooxycarbonylamino]acrylate.

[0186] (Epoxy)

[0187] Examples of the compound having an epoxy group include various chain epoxy group-containing monomers (e.g., glycidyl (meth)acrylate, β-methyl glycidyl (meth)acrylate, glycidyl vinyl ether, allyl glycidyl ether, etc.), various (2-oxo-1,3-oxolane) group-containing vinyl monomers (e.g., (2-oxo-1,3-oxolane) methyl (meth)acrylate, etc.), various alicyclic epoxy group-containing vinyl monomers (e.g., 3,4-epoxycyclohexyl (meth)acrylate, 3,4-epoxycyclohexyl methyl (meth)acrylate, 3,4-epoxycyclohexyl ethyl (meth)acrylate, etc.), bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol A diglycidyl ether, and brominated bisphenol B. Bisphenol F diglycidyl ether, brominated bisphenol S diglycidyl ether, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether; polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides to an aliphatic polyol such as ethylene glycol, propylene glycol, or glycerol; diglycidyl esters of aliphatic long-chain dibasic acids; monoglycidyl ethers of aliphatic higher alcohols; monoglycidyl ethers of polyether alcohols obtained by adding alkylene oxides to phenol, cresol, butylphenol, or any of these; glycidyl esters of higher fatty acids, etc.

[0188] Moreover, as a compound which has an epoxy group, the compound which has a (meth)acryloyl group and an epoxy group, the partial (meth)acryl compound of an epoxy compound, etc. are mentioned.

[0189] Examples of the compound having a (meth)acryloyl group and an epoxy group include glycidyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate glycidyl ether.

[0190] The partially (meth)acrylated epoxy compound is obtained by reacting an epoxy compound with (meth)acrylic acid in the presence of a catalyst according to a conventional method. Examples of epoxy compounds that can be used for the partially (meth)acrylated epoxy compound include novolac-type epoxy compounds and bisphenol-type epoxy compounds. Examples of the novolac-type epoxy compound include phenol novolac-type epoxy compounds, cresol novolac-type epoxy compounds, biphenyl novolac-type epoxy compounds, trisphenol novolac-type epoxy compounds, and dicyclopentadiene novolac-type epoxy compounds. Examples of the bisphenol-type epoxy compound include bisphenol A-type epoxy compounds, bisphenol F-type epoxy compounds, 2,2′-diallylbisphenol A-type epoxy compounds, hydrogenated bisphenol-type epoxy compounds, and polyoxypropylene bisphenol A-type epoxy compounds. By appropriately varying the amounts of the epoxy compound and (meth)acrylic acid, an epoxy compound having a desired acrylate ratio can be obtained.

[0191] ((Meth)acryloyl)

[0192] "(Meth)acryloyl" refers to acryloyl or methacryloyl. Compounds having a (meth)acryloyl group include, for example, isoamyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, isomyristyl (meth)acrylate, isostearyl (meth)acrylate, 2-ethylhexyl-diglycol (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalate, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, methoxydiethylene glycol (meth)acrylate. Monofunctional esters such as esters, methoxy polyethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, ethyl 2-(meth)acryloyloxysuccinate, ethyl 2-(meth)acryloyloxyphthalate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl-phthalate, and tert-butylcyclohexyl (meth)acrylate Acrylates; and acrylates including triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dihydroxymethyl-tricyclodecane di(meth)acrylate, PO adduct of bisphenol A di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, difunctional acrylates including trifunctional or higher acrylates such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerol trihydroxypropyl tri(meth)acrylate and pentaerythritol ethoxy tetra(meth)acrylate, etc.

[0193] Among the compounds having a (meth)acryloyl group, (meth)acrylate compounds having an imide group are preferred from the viewpoint of improving resistance to high temperature and high humidity.

[0194] In the case of (meth)acrylate compounds having an imide group, strong metal adhesion can be obtained due to the high polarity of the imide group. In addition, since the imide group itself has strong cohesive force, it has little effect on metal adhesion under high humidity.

[0195] Examples of the (meth)acrylate compound having an imide group include imide acrylates or imide methacrylates described in JP-A-10-36462 and JP-A-11-21470.

[0196] (Maleimido)

[0197] Examples of the compound having a maleimide group include N-methylmaleimide, N-ethylmaleimide, N-hexylmaleimide, N-propylmaleimide, N-butylmaleimide, N-octyl ester maleimide, N-dodecylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-p-carboxyphenylmaleimide, N-p-hydroxyphenylmaleimide, N-p-chlorophenylmaleimide, Phenylmaleimide, N-p-tolylmaleimide, N-p-xylylmaleimide, N-o-chlorophenylmaleimide, N-o-tolylmaleimide, N-benzylmaleimide, N-2,5-diethylphenylmaleimide, N-2,5-dimethylphenylmaleimide, N-m-tolylmaleimide, N-α-naphthylmaleimide, N-o-xylylmaleimide, N-m-xylene 1,2-Bismaleimide, bismaleimide methane, 1,6-bismaleimide hexane, bismaleimide dodecane, N,N'-m-phenylene bismaleimide, N,N'-p-phenylene dimaleimide, 4,4'-bismaleimide diphenyl ether, 4,4'-bismaleimide diphenylmethane, 4,4'-bismaleimide-bis(3-methylphenyl)methane, 4,4'-bismaleimide Imide-bis(3-ethylphenyl)methane, 4,4'-bismaleimide-bis(3-methyl-5-ethyl-phenyl)methane, N,N'-(2,2-bis-(4-phenoxyphenyl)propane) dimaleimide, N,N'-2,4-toluene dimaleimide, N,N'-2,6-toluene dimaleimide, N,N'-m-xylylenedimaleimide, bisphenol A diphenyl ether bismaleimide, etc.

[0198] (Sulfhydryl)

[0199] Examples of the compound having a mercapto group include ethyl thioacrylate, ethyl thiomethacrylate, biphenyl thioacrylate, biphenyl thiomethacrylate, nitrophenyl thioacrylate, nitrophenyl thiomethacrylate, triphenylmethyl thioacrylate, triphenylmethyl thiomethacrylate, 1,2-bis[(2-mercaptoethyl)thio]-3-mercaptopropane triacrylate, 2-(mercaptomethyl)-methyl 2-propanoate, 2-[(2-mercaptoethyl)thio]ethyl methacrylate, 1,4-bis(3-mercaptobutyryloxy)butane, and 1,3,5-tris(3-mercaptobutyryloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione.

[0200] (Alkoxy)

[0201] Examples of the compound having an alkoxy group include methoxymethyl acrylate, methoxymethyl methacrylate, dimethoxymethyl acrylate, dimethoxymethyl methacrylate, 1-methoxyethyl acrylate, 1-methoxyethyl methacrylate, 2-methoxyethyl acrylate, 2-methoxyethyl methacrylate, 1,1-methoxyethyl acrylate, 1,1-methoxyethyl methacrylate, 1-ethoxyethyl acrylate, 1-ethoxyethyl methacrylate, 2-ethoxyethyl acrylate, 2-ethoxyethyl methacrylate, N-ethoxymethylacrylamide, N-ethoxymethylmethacrylamide, ethoxymethyl acrylate, ethoxymethyl methacrylate, and acrylic acid-modified alkylated melamine.

[0202] (Other functional groups)

[0203] As the thermosetting functional group, in addition to the above functional groups, there can be mentioned those having an oxetane group, Azoline-based compound.

[0204] Examples of the compound having an oxetane group include oxetane (meth)acrylate, etc. Examples of commercially available products of such a compound include OXE-10 and OXE-30, manufactured by Osaka Organic Chemical Co., Ltd.

[0205] As a Examples of oxazoline compounds include 2-isopropenyl-2- Oxazoline, 2-isopropenyl-4-methyl-2- Oxazoline, 2-isopropenyl-5-ethyl-2- Oxazoline, 2-vinyl-2- Oxazoline, 2-vinyl-4-methyl-2- Oxazoline, 2-vinyl-5-methyl-2- Oxazoline and its Azoline-based monomers Monomers having a substituent on the oxazoline group, etc.

[0206] (2) Gelling agent

[0207] The gelling agent contained in the ink of the present invention is preferably maintained in a uniformly dispersed state in the cured film cured by light and heat, thereby preventing moisture from penetrating into the cured film.

[0208] From the perspective of dispersing in the cured film without hindering the curability of the ink, such a gelling agent is preferably at least one compound represented by the following general formula (G1) or (G2). Furthermore, in inkjet printing, it is preferred because it provides good pinning properties, enables drawing with both thin lines and thick films, and exhibits excellent thin line reproducibility.

[0209] General formula (G1): R1-CO-R2

[0210] General formula (G2): R3-COO-R4

[0211] [In the formula, R1 to R4 each independently represent an alkyl chain having a linear portion having 12 or more carbon atoms and optionally having a branch.]

[0212] Since the linear or branched hydrocarbon group (alkyl chain) of the ketone wax represented by the general formula (G1) or the ester wax represented by the general formula (G2) has 12 or more carbon atoms, the crystallinity of the gelling agent is further improved, thereby enhancing water resistance and creating more ample space in the card chamber structure described below. Consequently, ink media such as solvents and photopolymerizable compounds are easily enclosed within this space, further enhancing the ink's pinning properties.

[0213] The number of carbon atoms in the linear or branched hydrocarbon group (alkyl chain) is preferably 26 or less. If it is 26 or less, the melting point of the gelling agent will not be excessively increased, and therefore the ink does not need to be excessively heated when ejecting the ink.

[0214] From the above viewpoints, R1 and R2 or R3 and R4 are particularly preferably linear hydrocarbon groups having 12 to 23 carbon atoms.

[0215] Furthermore, from the viewpoint of increasing the gelation temperature of the ink and gelling the ink more quickly after landing, it is preferred that either R1 or R2 or either R3 or R4 is a saturated hydrocarbon group having 12 to 23 carbon atoms.

[0216] From the above viewpoints, it is more preferred that both R1 and R2 or both R3 and R4 are saturated hydrocarbon groups having 11 or more and less than 23 carbon atoms.

[0217] Examples of ketone waxes represented by the general formula (G1) include ditetracosanone (C24-C24), dibehenyl ketone (C22-C22), distearyl ketone (C18-C18), dieicosanone (C20-C20), dipalmityl ketone (C16-C16), dimyristyl ketone (C14-C14), dilauryl ketone (C12-C12), lauryl myristyl ketone (C16-C16), and dioctyl ketone (C14-C14). Myristyl ketone (C12-C14), palmityl laurate ketone (C12-C16), myristyl palmityl ketone (C14-C16), myristyl stearyl ketone (C14-C18), myristyl behenyl ketone (C14-C22), palmityl stearyl ketone (C16-C18), palmitoyl behenyl ketone (C16-C22), and stearyl behenyl ketone (C18-C22). The carbon atom numbers in parentheses above represent the carbon atom numbers of the two hydrocarbon groups separated by the carbonyl group.

[0218] Examples of commercially available products of the ketone wax represented by the general formula (G1) include Stearonne (manufactured by Alfa Aeser; STEARONNE), 18-Pentatriacontanon (manufactured by Alfa Aeser), Hentriacontan-16-on (manufactured by Alfa Aeser), and KAOWAX T-1 (manufactured by Kao Corporation).

[0219] Examples of fatty acid or ester waxes represented by general formula (G2) include behenyl behenate (C21-C22), eicosyl eicosate (C19-C20), stearyl stearate (C17-C18), palmityl stearate (C17-C16), laurate stearate (C17-C12), cetyl palmitate (C15-C16), stearyl palmitate (C15-C18), myristyl myristate (C13-C14), cetyl myristate (C13-C16), octyldodecyl myristate (C13-C20), stearyl oleate (C17-C18), stearyl erucate (C21-C18), stearyl linoleate (C17-C18), behenyl oleate (C18-C22), and arachidyl linoleate (C17-C20). It should be noted that the number of carbon atoms in the above brackets represents the number of carbon atoms in each of the two hydrocarbon groups separated by the ester group.

[0220] Examples of commercially available products of the ester wax represented by general formula (G2) include Unistar M-2222SL and SPERMACETI, manufactured by NOF Corporation ("Unistar" is a registered trademark of the company), EXCEPARL SS and EXCEPARL MY-M, manufactured by Kao Corporation ("EXCEPARL" is a registered trademark of the company), EMALEX CC-18 and EMALEX CC-10, manufactured by Nippon Emulsion Co., Ltd. ("EMALEX" is a registered trademark of the company), and Amreps PC, manufactured by Advanced Alcohol Industry Co., Ltd. ("Amreps" is a registered trademark of the company).

[0221] Most of these commercially available products are mixtures of two or more and can therefore be separated and purified as needed before inclusion in the ink. Among these gelling agents, ketone waxes, ester waxes, higher fatty acids, higher alcohols, and fatty acid amides are preferred from the viewpoint of further improving pinning properties.

[0222] The gelling agent content of the present invention is preferably within the range of 0.5 to 5.0% by mass relative to the total mass of the ink. By setting the gelling agent content within this range, the gelling agent exhibits excellent solubility and pinning properties in the solvent component, and the resulting cured film exhibits excellent water resistance. Furthermore, from this perspective, the gelling agent content in the inkjet ink is more preferably within the range of 0.5 to 2.5% by mass.

[0223] Furthermore, from the following perspective, it is preferable that the gelling agent crystallizes within the ink at a temperature below the ink's gelation temperature. The gelation temperature refers to the temperature at which, when the ink, which has been solified or liquefied by heating, undergoes a phase transition from sol to gel, causing the ink's viscosity to suddenly change. Specifically, the viscosity of the solified or liquefied ink is measured using a viscoelasticity measuring instrument (e.g., MCR300, manufactured by Physica) while cooling, and the temperature at which the viscosity suddenly increases is defined as the gelation temperature of the ink.

[0224] (3) Compounds with photopolymerizable functional groups

[0225] The compound having a photopolymerizable functional group (also referred to as a photopolymerizable compound) contained in the ink of the present invention can be a compound that undergoes polymerization or crosslinking reaction upon exposure to active light, thereby curing the ink. Examples of photopolymerizable compounds include free radical polymerizable compounds and cationically polymerizable compounds.

[0226] The photopolymerizable compound may be any of a monomer, a polymerizable oligomer, a prepolymer, or a mixture thereof. The inkjet ink may contain only one photopolymerizable compound or two or more photopolymerizable compounds.

[0227] The radical polymerizable compound is preferably an unsaturated carboxylic acid ester compound, more preferably a (meth)acrylate. Examples of such a compound include the aforementioned compounds having a (meth)acryloyl group.

[0228] Examples of the cationically polymerizable compound include epoxy compounds, vinyl ether compounds, and oxetane compounds. The inkjet ink may contain only one type of cationically polymerizable compound, or may contain two or more types.

[0229] (4) Photopolymerization initiator

[0230] The photopolymerization initiator used in the ink of the present invention is preferably a photoradical initiator when the photopolymerizable compound is a radical polymerizable compound, and is preferably a photoacid generator when the photopolymerizable compound is a cationically polymerizable compound.

[0231] The ink of the present invention may contain only one photopolymerization initiator or two or more. The photopolymerization initiator may be a combination of a photoradical initiator and a photoacid generator. Photoradical initiators may include cleavage-type free radical initiators and hydrogen abstraction-type free radical initiators.

[0232] Examples of the cleavage-type free radical initiator include acetophenone-based initiators, benzoin-based initiators, acylphosphine oxide-based initiators, benzyl and methyl phenyl glyoxyesters.

[0233] Examples of acetophenone-based initiators include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenyl ketone, 2-methyl-2-morpholino(4-thiomethylphenyl)propane-1-one, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone.

[0234] Examples of the benzoin-based initiator include benzoin, benzoin methyl ether, and benzoin isopropyl ether.

[0235] Examples of the acylphosphine oxide-based initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

[0236] Examples of the hydrogen abstraction type free radical initiator include benzophenone-based initiators, thioxanthone-based initiators, aminobenzophenone-based initiators, 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10-phenanthrenequinone, and camphorquinone.

[0237] Examples of benzophenone-based initiators include benzophenone, methyl o-benzoylbenzoate-4-phenylbenzophenone, 4,4′-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyl-diphenyl sulfide, acrylated benzophenone, 3,3′,4,4′-tetrakis(tert-butylperoxycarbonyl)benzophenone, and 3,3′-dimethyl-4-methoxybenzophenone.

[0238] Examples of the thioxanthone-based initiator include 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, and 2,4-dichlorothioxanthone.

[0239] Examples of the aminobenzophenone-based initiator include Michelle's ketone and 4,4′-diethylaminobenzophenone.

[0240] Examples of the photoacid generator include compounds described in "Organic Materials for Imaging", edited by the Organic Electronics Materials Research Society, Bunshin Shuppan (1993), pp. 187-192.

[0241] The content of the photopolymerization initiator may be within a range that allows the ink to be sufficiently cured, and may be, for example, within a range of 0.01 to 10% by mass relative to the total mass of the ink of the present invention.

[0242] Examples of commercially available photopolymerization initiators include Irgacure TPO (manufactured by BASF), 819 (manufactured by BASF), Irgacure 379 (manufactured by BASF), Genocure ITX (manufactured by Rahn AG), and Genocure EPD (manufactured by Rahn AG).

[0243] The ink of the present invention may further contain a photopolymerization initiator auxiliary, a polymerization inhibitor, and the like as needed.

[0244] The photopolymerization initiator auxiliary may be a tertiary amine compound, preferably an aromatic tertiary amine compound.

[0245] Examples of aromatic tertiary amine compounds include N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethyl-p-toluidine, N,N-dimethylamino-p-terephthalate, N,N-dimethylamino-p-terephthalate isopentylethyl ester, N,N-dihydroxyethylaniline, triethylamine, and N,N-dimethylhexylamine. Among these, N,N-dimethylamino-p-terephthalate and N,N-dimethylamino-p-terephthalate are preferred. These compounds may be used alone or in combination of two or more.

[0246] (5) Colorants

[0247] The ink of the present invention may further contain a colorant as needed.

[0248] The colorant may be a dye or a pigment. Pigments are preferred due to their good dispersibility with respect to the structural components of the ink and excellent weather resistance. The pigment is not particularly limited, and examples thereof include the organic pigments or inorganic pigments numbered as described below in the Color Index.

[0249] Examples of red or magenta pigments include those selected from Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53:1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144, 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange The pigments of 13, 16, 20 and 36 or mixtures thereof.

[0250] Examples of blue or cyan pigments include pigments selected from Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17-1, 22, 27, 28, 29, 36, and 60, or mixtures thereof.

[0251] Examples of green pigments include pigments selected from Pigment Green 7, 26, 36, 50, or mixtures thereof.

[0252] Examples of yellow pigments include pigments selected from Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, and 193, or mixtures thereof.

[0253] Examples of the black pigment include pigments selected from Pigment Black 7, 28, and 26, or mixtures thereof.

[0254] Examples of commercially available pigments include Black Pigment (manufactured by Mikuni Co., Ltd.), CHROMOFINE YELLOWs 2080, 5900, 5930, AF-1300, 2700L, CHROMOFINE ORANGEs 3700L, 6730, CHROMOFINE SCARLET 6750, CHROMOFINE MAGENTAS 6880, 6886, 6891N, 6790, 6887, CHROMOFINE VIOLET RE, CHROMOFINE REDs 6820, 6830, and CHROMOFINE BLUEs. HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P, CHROMOFINE GREEN 2GN, 2GO, 2G-550D, 5310, 5370, 6830, CHROMOFINE BLACK A-1103, SEIKAFAST YELLOWs 10GH, A-3, 2035, 2054, 2200, 2270, 2300, 2400(B), 2500, 2600, ZAY-260, 2700(B), 2770, SEIKAFAST REDs 8040, C405(F), CA120, LR-116, 1531B, 8060R, 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, SEIKAFAST CARMINEs 6B1476T-7, 1483LT, 3840, 3870, SEIKAFAST BORDEAUX 10B-430, SEIKALIGHT ROSE R40, SEIKALIGHT VIOLETs B800, 7805, SEIKAFAST MAROON 460N, SEIKAFAST ORANGEs 900, 2900, SEIKALIGHT BLUEs C718、A612、CYANINE BLUEs 4933M, 4933GN-EP, 4940, 4973 (manufactured by Dainichi Seika Industries, Ltd.);KET Yellow 401, 402, 403, 404, 405, 406, 416, 424, KET Orange 501, KET Red 301, 302, 303, 304, 305, 306, 307, 308, 309, 310, 336, 337, 338, 346, KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124, KET Green 201 (made by DIC Corporation); Colortex Yellow 301, 314, 315, 316, P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T-05, Pigment Yellow1705, Colortex Orange 202, Colortex Red 101, 103, 115, 116, D3B, P-625, 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, 105C, USN, Colortex Maroon 601, Colortex Brown B610N, Colortex Violet 600, Pigment Red 122, Colortex Blue 516, 517, 518, 519, A818, P-908, 510, Colortex Green 402, 403, Colortex Black 702, U905 (Sanyo Pigments Co., Ltd.); Lionol Yellow 1405G, Lionol Blue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (manufactured by Toyo Ink Co., Ltd.), Toner Magenta E02, Permanent Rubin F6B, Toner Yellow HG, Permanent Yellow GG-02, Hostaperm Blue B2G (manufactured by Hoechst Industry Co., Ltd.); Novoperm P-HG, Hostaperm Pink E, Hostaperm Blue B2G (manufactured by Clariant);Carbon Blacks #2600, #2400, #2350, #2200, #1000, #990, #980, #970, #960, #950, #850, MCF88, #750, #650, MA600, MA7, MA8, MA11, MA100, MA100R, MA77, #52, #50, #47, #45, #45L, #40, #33, #32, #30, #25, #20, #10, #5, #44, and CF9 (Mitsubishi Chemical), etc.

[0255] The pigment can be dispersed by, for example, a ball mill, a sand mill, an attritor, a roll mill, a stirrer, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a bead mill, a wet airflow mill, a paint shaker, or the like.

[0256] The pigment is dispersed so that the volume average particle size of the pigment particles is preferably within the range of 0.08 to 0.5 μm, and the maximum particle size is preferably within the range of 0.3 to 10 μm, more preferably within the range of 0.3 to 3 μm.

[0257] The dispersion of the pigment is adjusted by selecting the pigment, dispersant and dispersion medium, as well as the dispersion conditions and filtration conditions.

[0258] In order to improve the dispersibility of the pigment, the ink of the present invention may further contain a dispersant.

[0259] Examples of dispersants include carboxylic acid esters having a hydroxyl group, salts of long-chain polyaminoamides and high-molecular-weight acid esters, salts of high-molecular-weight polycarboxylic acids, salts of long-chain polyaminoamides and polar acid esters, high-molecular-weight unsaturated acid esters, polymer copolymers, modified polyurethanes, modified polyacrylates, polyetherester anionic surfactants, naphthalenesulfonic acid formalin condensate salts, aromatic sulfonic acid formalin condensate salts, polyoxyethylene alkyl phosphates, polyoxyethylene nonylpropyl ether, and octadecylamine acetate. Examples of commercially available dispersants include Solsperse series from Avecia, PB series from Ajinomoto FineTechno, and the like.

[0260] The ink of the present invention may further contain a dispersing aid as needed. The dispersing aid may be selected according to the pigment.

[0261] The total amount of the dispersant and the dispersing aid is preferably within a range of 1 to 50% by mass based on the pigment.

[0262] The ink of the present invention may further contain a dispersion medium for dispersing the pigment as needed. As the dispersion medium, the ink may contain a solvent. In order to suppress the solvent from remaining in the formed image, it is preferred to use the above-mentioned photopolymerizable compound (particularly a low-viscosity monomer) as the dispersion medium.

[0263] Examples of the dye include oil-soluble dyes.

[0264] Examples of oil-soluble dyes include the following dyes. Examples of magenta dyes include MS Magenta VP, MS Magenta HM-1450, and MS Magenta HSo-147 (all manufactured by Mitsui Chemicals), AIZENSOT Red-1, AIZENSOT Red-2, AIZEN SOT Red-3, AIZEN SOT Pink-1, and SPIRON Red GEH SPECIAL (all manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN Red FB 200%, MACROLEX Red Violet R, and MACROLEX ROT5B (all manufactured by Bayer Japan Co., Ltd.), KAYASET Red B, KAYASET Red 130, and KAYASET Red 802 (all manufactured by Nippon Kayaku Co., Ltd.), PHLOXIN, ROSE BENGAL, and ACID Red (all manufactured by Daiwa Kasei Co., Ltd.), HSR-31, and DIARESIN Red K (all manufactured by Mitsubishi Chemical Co., Ltd.), and Oil Red (manufactured by BASF Japan Co., Ltd.).

[0265] Examples of cyan dyes include MS Cyan HM-1238, MS Cyan HSo-16, Cyan HSo-144, and MS Cyan VPG (all manufactured by Mitsui Chemicals, Inc.), AIZEN SOT Blue-4 (manufactured by Hodogaya Chemical Co., Ltd.), RESOLIN BR. Blue BGLN 200%, MACROLEX Blue RR, CERES Blue GN, SIRIUS SUPRATURQ. Blue Z-BGL, and SIRIUS SUPRATURQ. Blue FB-LL330% (all manufactured by Bayer Japan Co., Ltd.), KAYASET Blue FR, KAYASET Blue N, KAYASET Blue 814, Turq. Blue GL-5 200, and Light Blue BGL-5200 (all manufactured by Nippon Kayaku Co., Ltd.), DAIWA Blue 7000, and Oleosol Fast Blue GL (all manufactured by Daiwa Kasei Co., Ltd.), DIARESIN Blue P (manufactured by Mitsubishi Chemical Co., Ltd.), and SUDAN Blue. 670, NEOPEN Blue 808 and ZAPON Blue 806 (all manufactured by BASF Japan Co., Ltd.), etc.

[0266] Examples of yellow dyes include MS Yellow HSm-41, Yellow KX-7, and Yellow EX-27 (manufactured by Mitsui Chemicals, Inc.), AIZENSOT Yellow-1, AIZEN SOT Yellow W-3, and AIZEN SOT Yellow-6 (all manufactured by Hodogaya Chemical Co., Ltd.), MACROLEX Yellow 6G, and MACROLEX FLUOR. Yellow 10GN (all manufactured by Bayer Japan Co., Ltd.), KAYASET Yellow SF-G, KAYASET Yellow 2G, KAYASET Yellow AG, and KAYASET Yellow E-G (all manufactured by Nippon Kayaku Co., Ltd.), DAIWA Yellow 330HB (manufactured by Daiwa Kasei Co., Ltd.), HSY-68 (manufactured by Mitsubishi Chemical Co., Ltd.), SUDAN Yellow 146, and NEOPEN Yellow 075 (all manufactured by BASF Japan Co., Ltd.).

[0267] Examples of black dyes include MS Black VPC (manufactured by Mitsui Chemicals, Inc.), AIZEN SOT Black-1, AIZEN SOT Black-5 (all manufactured by Hodogaya Chemical Co., Ltd.), RESORIN Black GSN 200%, RESOLIN Black BS (all manufactured by Bayer Japan Co., Ltd.), KAYASET Black A-N (manufactured by Nippon Kayaku Co., Ltd.), DAIWA Black MSC (manufactured by Daiwa Kasei Co., Ltd.), HSB-202 (manufactured by Mitsubishi Chemical Co., Ltd.), NEPTUNE Black X60, and NEOPEN Black X58 (all manufactured by BASF Japan Co., Ltd.).

[0268] The ink of the present invention may contain one or more colorants to adjust the color to a desired color. The content of the colorant is preferably in the range of 0.1 to 20% by mass, more preferably in the range of 0.4 to 10% by mass, relative to the total amount of the ink.

[0269] (5) Other ingredients

[0270] The ink of the present invention may further contain other components, including a polymerization inhibitor and a surfactant, within the scope of the present invention. The ink of the present invention may contain only one of these components, or may contain two or more.

[0271] (Polymerization Inhibitor)

[0272] Examples of the polymerization inhibitor include (alkyl)phenol, hydroquinone, catechol, resorcinol, p-methoxyphenol, t-butylcatechol, t-butylhydroquinone, pyrogallol, 1,1-picrylhydrazine, phenothiazine, p-benzoquinone, nitrosobenzene, 2,5-di-t-butyl-p-benzoquinone, dithiobenzoyl disulfide, picric acid, cupferron, N-nitrosophenylhydroxylamine aluminum, tris-p-nitrobenzyl, N-(3-oxyanilino-1,3-dimethylbutylidene)aniline oxide, dibutylcresol, cyclohexanone oxime cresol, guaiacol, o-isopropylphenol, butyraldehyde oxime, methyl ethyl ketone oxime, and cyclohexanone oxime.

[0273] Examples of commercially available polymerization inhibitors include Irgastab UV10 (manufactured by BASF) and Genorad 18 (manufactured by Rahn AG).

[0274] The amount of the polymerization inhibitor can be arbitrarily set within a range in which the effects of the present invention are obtained.

[0275] The amount of the polymerization inhibitor may be, for example, 0.001% by mass or more and less than 1.0% by mass relative to the total mass of the ink.

[0276] (Surfactant)

[0277] Examples of surfactants include anionic surfactants such as dialkyl sulfosuccinates, alkylnaphthalene sulfonates, and fatty acid salts, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, and polyoxyethylene-polyoxypropylene block copolymers, cationic surfactants such as alkylamine salts and quaternary ammonium salts, and silicone-based and fluorine-based surfactants.

[0278] Examples of silicone-based surfactants include polyether-modified polysiloxane compounds, specifically Tegorad 2250, manufactured by Evonik, KF-351A, KF-352A, KF-642, and X-22-4272, manufactured by Shin-Etsu Chemical Co., Ltd., BYK 307, BYK 345, BYK 347, and BYK 348, manufactured by Big Chemie ("BYK" is a registered trademark of the company), and TSF 4452, manufactured by Momentive Performance Materials.

[0279] The fluorine-based surfactant is a surfactant in which part or all of the hydrogen atoms bonded to the carbon atoms of the hydrophobic group of a general surfactant are substituted with fluorine atoms.

[0280] Examples of fluorine-based surfactants include Megafac F, manufactured by DIC Corporation ("Megafac" is a registered trademark of the company), Surflon, manufactured by AGC Seichemical Co., Ltd. ("Surflon" is a registered trademark of the company), Fluorad FC, manufactured by 3M Co. ("Fluorad" is a registered trademark of the company), Monflor, manufactured by Imperial Chemical Industries, Ltd., Zonyls, manufactured by EI DuPont Nemerus and Company, Licowet VPF, manufactured by Lubeberke-Hoechst, and FTERGENT, manufactured by Neos Corporation ("FTERGENT" is a registered trademark of the company).

[0281] The amount of the surfactant can be arbitrarily set within a range that allows the effects of the present invention to be achieved. For example, the amount of the surfactant can be 0.001% by mass or more and less than 1.0% by mass relative to the total mass of the ink.

[0282] (Curing Accelerator)

[0283] The ink of the present invention may contain a curing accelerator as needed. Any curing accelerator can be used without particular limitation as long as it accelerates the thermal curing of the resin component.

[0284] Examples of the curing accelerator include imidazoles, dicyandiamide derivatives, dicarboxylic acid dihydrazides, triphenylphosphine, tetraphenylphosphine, Tetraphenyl borate, 2-ethyl-4-methylimidazole-tetraphenyl borate and 1,8-diazabicyclo[5.4.0]undecenyl-7-tetraphenyl borate, etc.

[0285] (Coupling agent)

[0286] The ink of the present invention may contain various coupling agents as needed. By containing a coupling agent, the adhesion to the copper foil can be improved.

[0287] Examples of the various coupling agents include silane-based, titanium-based, and aluminum-based coupling agents.

[0288] (Ion Scavenger)

[0289] The ink of the present invention may contain an ion scavenger as needed. The inclusion of the ion scavenger has advantages such as adsorption of ionic impurities and improved insulation properties of the cured film under hygroscopic conditions.

[0290] Examples of the ion scavenger include inorganic ion adsorbents such as triazine thiol compounds, bisphenol-based reducing agents, zirconium compounds, and antimony-bismuth-based magnesium-aluminum compounds.

[0291] (Solvent)

[0292] The ink of the present invention is preferably solvent-free from the viewpoint of curability, but a solvent may be added to adjust the viscosity of the ink.

[0293] <Ink Properties>

[0294] The ink of the present invention can be suitably used as an inkjet ink if the ink has a viscosity of 3 to 20 mPa·s, more preferably 5 to 15 mPa·s, when heated in the range of 30 to 100°C. The ink of the present invention is more preferably an ink containing a gelling agent and having a viscosity of 1 to 1×10 4 Inks within the range of Pa·s are preferably used because the ink is sufficiently gelled when the ink is deposited and cooled to room temperature, resulting in good pinning properties.

[0295] The ink of the present invention preferably has a phase transition point within the range of 40°C to less than 100°C. When the phase transition point is 40°C or higher, the ink quickly gels after landing on the recording medium, resulting in improved pinning properties. Furthermore, when the phase transition point is less than 100°C, the ink has good handleability and high ejection stability.

[0296] From the viewpoint of being able to eject the ink at a lower temperature and reducing the load on the image forming apparatus, the phase transition point of the ink of the present invention is more preferably within the range of 40 to 60°C.

[0297] The viscosity and phase transition point of the ink of the present invention can be obtained by measuring the temperature change of the dynamic viscoelasticity of the ink using a rheometer.

[0298] In the present invention, these viscosities and phase transition points are values obtained by the following method: The measurement temperature is preferably adjusted appropriately according to the ink.

[0299] The ink of the present invention is heated to 100°C, and the viscosity is measured using a stress-controlled rheometer, Physica MCR301 (cone plate diameter: 75 mm, cone angle: 1.0°), manufactured by Anton Paar. Simultaneously, the ink is cooled to 20°C at a shear rate of 11.7 (1 / s) and a cooling rate of 0.1°C / s to obtain a viscosity temperature change curve.

[0300] For example, the viscosity at 80°C (discharge temperature) and the viscosity at 25°C (substrate landing temperature) can be determined by reading the viscosity at 80°C and 25°C, respectively, from the viscosity temperature curve. The phase transition point can be determined from the viscosity temperature curve as the temperature at which the viscosity reaches 200 mPa·s.

[0301] From the perspective of further improving the ejection performance from the inkjet head, the average dispersed particle size of the pigment particles of the present invention is in the range of 50 to 150 nm, and the maximum particle size is preferably in the range of 300 to 1000 nm. More preferably, the average dispersed particle size is in the range of 80 to 130 nm.

[0302] The average dispersed particle size of the pigment particles in this invention is determined by dynamic light scattering using a Datasizer NanoZSP manufactured by Malvern. Note that since the colorant-containing ink has a high concentration and does not transmit light through the measurement instrument, the measurement was performed after diluting the ink 200-fold. The measurement temperature was room temperature (25°C).

[0303] <Method for forming a solder resist film>

[0304] The ink of the present invention is preferably used as an ink for forming a solder resist pattern on a printed circuit board. When the ink of the present invention is used to form a solder resist pattern (solder resist film), moisture penetration into the solder resist film is prevented, resulting in improved adhesion between the copper foil of the printed circuit board and the solder resist film. Furthermore, copper migration is prevented, suppressing a decrease in insulation properties.

[0305] The method for forming a solder resist film using the ink of the present invention preferably includes: (1) ejecting the ink of the present invention from the nozzle of an inkjet head and depositing it on a printed circuit board having a circuit formed thereon; and (3) heating the ink for primary curing.

[0306] When the ink of the present invention contains a compound having a photopolymerizable functional group and a photopolymerization initiator, it is preferred to include a step (step (2)) of irradiating the deposited ink with active light to temporarily cure the ink between the steps (1) and (3) above.

[0307] (1) Process

[0308] In step (1), droplets of the ink of the present invention are ejected from an inkjet head and landed on positions corresponding to the resist film to be formed on a printed circuit board as a recording medium to perform patterning.

[0309] The ink jet head may be ejected in either an on-demand manner or a continuous manner.

[0310] On-demand inkjet heads can be any of the electromechanical conversion methods such as single-chamber type, dual-chamber type, curved type, piston type, shared pattern type and shared wall type, as well as electrothermal conversion methods such as thermal inkjet type and Bubble Jet (registered trademark) (Bubble Jet is a registered trademark of Canon) type.

[0311] Ejecting ink droplets from the inkjet head while heated can improve ejection stability. The ink temperature during ejection is preferably between 40 and 100°C, and more preferably between 40 and 90°C to further improve ejection stability. It is particularly preferred to eject at an ink temperature that allows the ink viscosity to be between 7 and 15 mPa·s, and more preferably between 8 and 13 mPa·s.

[0312] To improve the ejectability of sol-gel phase change inks from an inkjet head, it is preferable to set the ink temperature when filling the inkjet head to between (gelation temperature + 10)°C and (gelation temperature + 30)°C. If the ink temperature within the inkjet head is lower than (gelation temperature + 10)°C, the ink will gel within the inkjet head or on the nozzle surface, which can reduce the ink's ejectability. On the other hand, if the ink temperature within the inkjet head exceeds (gelation temperature + 30)°C, the ink temperature becomes too high, potentially degrading the ink components.

[0313] The method for heating the ink is not particularly limited. For example, at least one of the ink supply system, including the ink tank of the print head carriage, the supply pipe, the ink tank in front of the nozzle, the piping with the filter, and the piezoelectric head, can be heated by a plate heater, a tape heater, or warm water.

[0314] From the perspective of recording speed and image quality, the amount of ink droplets during discharge is preferably within a range of 2 to 20 pL.

[0315] The printed circuit board is not particularly limited. For example, it is preferred to use copper-clad laminates of all grades (FR-4, etc.) of materials such as paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / non-woven epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluorine·polyethylene·PPO·cyanate ester, etc. for high-frequency circuits, other polyimide films, PET films, glass substrates, ceramic substrates, chip boards, and stainless steel plates.

[0316] (2) Process

[0317] In the step (2), the ink deposited in the step (1) is irradiated with active light to temporarily cure the ink.

[0318] The active light can be selected from, for example, electron beams, ultraviolet rays, α rays, γ rays, and X-rays, and ultraviolet rays are preferred.

[0319] Ultraviolet irradiation can be performed at a wavelength of 395 nm using, for example, a water-cooled LED manufactured by Phoseon Technology Co., Ltd. Using an LED as a light source can suppress poor curing of the ink due to dissolution of the ink by radiant heat from the light source.

[0320] The peak illuminance of the ultraviolet ray on the resist film surface is preferably 0.5 to 10 W / cm 2 The range of W / cm is more preferably 1 to 5 W / cm 2 From the perspective of suppressing the radiant heat exposure of the ink, it is preferred that the amount of light irradiated to the resist film is less than 500 mJ / cm 2 .

[0321] The irradiation with active light rays is preferably performed within 0.001 to 300 seconds after the ink has landed, and more preferably within 0.001 to 60 seconds in order to form a high-definition resist film.

[0322] (3) Process

[0323] In the step (3), after the temporary curing in (2), the ink is further heated to perform the main curing.

[0324] As a heating method, for example, it is preferable to place the product in an oven set at a temperature within a range of 110 to 180° C. for 10 to 60 minutes.

[0325] In addition, the ink of the present invention can be used as an adhesive, a sealant, a circuit protective agent, etc. for electronic components, in addition to being used as the ink for forming the solder resist pattern described above.

[0326] Example

[0327] The present invention is further described below with reference to the following examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the operations were performed at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" refer to "mass %" and "mass parts," respectively.

[0328] <Preparation of yellow pigment dispersion>

[0329] Dispersants 1 and 2, along with the dispersion medium, were placed in a stainless steel beaker and heated on a 65°C hot plate while stirring for 1 hour to dissolve. After cooling to room temperature, the pigments listed below were added and placed in a sealed glass bottle along with 200g of 0.5mm diameter zirconia beads. The particles were dispersed using a paint shaker to the desired particle size, and the beads were removed.

[0330] Dispersant 1: 5.6 parts by mass of EFKA7701 (manufactured by BASF)

[0331] Dispersant 2: Solsperse 22000 (manufactured by Lubrizol Japan Co., Ltd.) 0.4 parts by mass

[0332] Dispersion medium: 80.6 parts by mass of dipropylene glycol diacrylate (containing 0.2% UV-10) Pigment: 13.4 parts by mass of PY185 (Paliotol Yellow D1155 manufactured by BASF)

[0333] <Preparation of cyan pigment dispersion>

[0334] The yellow pigment dispersion was prepared in the same manner except that the dispersant, dispersion medium, and pigment were changed as shown below.

[0335] Dispersant: 7 parts by mass of EFKA7701 (manufactured by BASF)

[0336] Dispersion medium: 70 parts by mass of dipropylene glycol diacrylate (containing 0.2% UV-10)

[0337] Pigment: PB15:4 (Dainichi Seika Co., Ltd., CHROMOFINE BLUEs 6332JC) 23 parts by mass

[0338] <Gelling agent>

[0339] As the gelling agent, the compound shown below was used.

[0340] Distearyl ketone

[0341] Behenyl Behenate

[0342] <Compounds having thermosetting functional groups>

[0343] The compounds shown in Table I below were used.

[0344]

[0345] <Compounds having a photopolymerizable functional group>

[0346] As the compound having a photopolymerizable functional group, the following compounds were used.

[0347] DPGTA (trade name: M222 (manufactured by Miwon))

[0348] TMP(EO)9TA (trade name: EM2382 (manufactured by Changxing Chemical Co., Ltd.)

[0349] <Photopolymerization initiator>

[0350] As the photopolymerization initiator, the following compounds were used.

[0351] TPO (made by BASF)

[0352] <Photosensitizer>

[0353] As photosensitizers, the following substances were used.

[0354] ITX (made by Lambson)

[0355] <Preparation of Inkjet Inks 1 and 2>

[0356] Ink compositions were prepared according to the following Table II and filtered using a 3 μm Teflon (registered trademark) membrane filter manufactured by ADVATEC Co., Ltd. Ink 1 contained an unblocked isocyanate, and ink 2 contained a pyrazole-based blocked isocyanate.

[0357]

[0358] <Pattern formation by inkjet>

[0359] Each prepared inkjet ink was loaded into an inkjet recording apparatus equipped with an inkjet recording head having a piezoelectric inkjet nozzle, and patterning was performed on a copper-clad laminate for a printed wiring board (FR-4, thickness 1.6 mm, size 150 mm x 95 mm).

[0360] Ink supply system such as Figure 3 The system shown uses a main ink tank, a first sub-ink tank, a degassing device, a second sub-ink tank, an ink flow path, a pipe with a metal filter, and a piezoelectric head.

[0361] In addition, the ink supply from the main ink tank to the first sub-ink tank is as described above. Figure 8 As shown in the flowchart, a valve (solenoid valve) 55, a supply pump 53, and a float sensor 241a are used.

[0362] The capacity of the second auxiliary ink tank is 100mL. As the shape of the second auxiliary ink tank, Figure 4 The figure shows a configuration in which a rubber heater 272 is provided on the outer surface of the side wall and the bottom of the second sub-ink tank 245 .

[0363] Furthermore, the capacity of the first sub-ink tank is 200 mL, and the following shapes are used as the shapes of the first sub-ink tank, as shown in Table III below.

[0364] Sub-tank A: The first sub-tank is configured such that no partition is provided in the first sub-tank, and a rubber heater is provided on the outer surface of the side wall and bottom of the first sub-tank. The surface area of the ink tank inner wall heated by the rubber heater and in contact with ink is approximately the same as the surface area of the ink tank inner wall heated by the rubber heater and in contact with ink in the second sub-tank.

[0365] Auxiliary ink tank B: Figure 5A and Figure 5B The structure is similar to that of the first auxiliary ink tank shown in FIG. Specifically, rubber heaters are provided on the outer surfaces of the side walls and bottom of the first auxiliary ink tank, and a partition is provided within the first auxiliary ink tank. The surface area of the ink tank inner wall heated by the rubber heater (the side walls 2411, the bottom 2412, and the partition 2415) in contact with ink is larger than the surface area of the ink tank inner wall heated by the rubber heater in contact with ink in the second auxiliary ink tank.

[0366] The ratio of the amount of ink newly supplied from the main ink tank to the first sub-tank (supply amount) to the amount of ink remaining in the first sub-tank (residual amount) is set as shown in Table III below. Furthermore, the ink flowing from the first sub-tank to the print head is heated to 85°C. A heater is also built into the piezoelectric head to heat the ink temperature within the recording head to 80°C. The piezoelectric head used is the Konica Minolta KM1024iSHE-C, with a nozzle resolution of 360 dpi. The heads are arranged in a staggered pattern, achieving a nozzle resolution of 360 dpi and a printing width of 140 mm.

[0367] Using this inkjet recording device, voltage was applied to form a dot with a droplet volume of 6.0 pl. Four passes of a 20 mm × 50 mm solid pattern and a 100 μm line & space comb pattern were printed on a substrate at a printing resolution of 1440 dpi × 1440 dpi, each with a thickness of 20 μm. The pattern was then illuminated with an LED lamp (395 nm, 8 W / cm²) manufactured by Phoseon Technology. 2 , watercooled unit) becomes 500mJ / cm 2 The ink layer was temporarily cured by irradiation. Then, the ink layer was placed in an oven set at 150°C for 60 minutes for main curing to obtain a printed sample.

[0368] [evaluate]

[0369] <Substrate Adhesion>

[0370] For the solid pattern printed samples, cuts were made in a checkerboard pattern on the cured film according to the cross-hatch method of JIS K5600. Adhesive tape was applied and peeled off. The peeled state of the cured film was observed, and the adhesion residual rate was calculated according to the following method and evaluated according to the following criteria. The adhesion residual rate was calculated using the number of squares formed by the cuts as the denominator and the number of squares remaining after tape peeling as the numerator. ◎, ○, and △ were considered acceptable.

[0371] (Benchmark)

[0372] ◎: Adhesion residual rate 100%

[0373] ○: Adhesion residual rate is 80% or more and less than 100%

[0374] △: Adhesion residual rate 60% or more and less than 80%

[0375] ×: less than 60% adhesion residual rate

[0376] <Solder Heat Resistance>

[0377] The printed sample of the solid pattern was immersed in a 260°C solder bath three times for 10 seconds each time, and then subjected to the above-mentioned evaluation of substrate adhesion, and the peeling state of the cured film was observed.

[0378] <Injection stability>

[0379] The above-described inkjet recording system was used to print 100 printed wiring boards, operating for 8 hours per day for 5 consecutive days. Printhead maintenance was performed at the start and stop of each operating day, with each printhead discharging 10cc of ink. After 8 hours of operation on the fifth operating day, a nozzle check pattern was printed. The frequency of non-discharging nozzles per total number of nozzles was evaluated according to the following criteria. For jetting stability, scores of 0 and ◎ were considered acceptable.

[0380] (Benchmark)

[0381] ◎: No nozzles that do not spray

[0382] ○: Several nozzles were observed to be non-discharging, but this was resolved through maintenance.

[0383] △: Several nozzles were observed to be non-discharging, and the problem was not resolved even after maintenance.

[0384] ×: Dozens or more nozzles were observed to be non-discharging, and the problem was not resolved even after maintenance.

[0385]

[0386] As shown in the above results, the example in which the amount of ink newly supplied from the main ink tank to the first sub-tank is set to be greater than the amount of ink remaining in the first sub-tank is superior to the comparative example in terms of substrate adhesion, solder heat resistance, and ejection stability.

[0387] In addition, the better result when the shape of the sub-tank B was used in the first sub-tank than when the shape of the sub-tank A was used is presumably due to the fact that by increasing the contact surface area between the ink and the rubber heater, the heating time for the ink inside the first sub-tank to reach the specified temperature can be shortened, thereby improving the ejection stability and substrate adhesion (coating film strength).

[0388] Furthermore, it was found that the case of using ink 2 containing blocked isocyanate had superior solder heat resistance compared to the case of using ink 1 containing unblocked isocyanate.

[0389] Industrial applicability

[0390] The present invention can be utilized in an inkjet recording method and an inkjet recording apparatus.

[0391] Explanation of symbols

[0392] 1: Inkjet recording device

[0393] 24a: Inkjet head

[0394] 40: Control Department

[0395] 51: Main ink tank

[0396] 53: Supply pump

[0397] 55: Valve

[0398] 241: First ink tank

[0399] 241a: Float sensor

[0400] 2411: Side wall

[0401] 2412: bottom

[0402] 2413: Inlet

[0403] 2414: Outflow

[0404] 242: Degassing device

[0405] 245: Second ink tank

[0406] 270: Heating device

[0407] 272: Rubber heater

Claims

1. An inkjet recording method for recording an image by ejecting ink from an inkjet head, comprising: The main ink tank serves as the ink supply source; a first auxiliary ink tank connected to the main ink tank to supply ink; a degassing device connected to the first auxiliary ink tank, for degassing the ink supplied from the first auxiliary ink tank; a second auxiliary ink tank for supplying the ink degassed by the degassing device to the inkjet head and controlling the negative pressure applied to the inkjet head; as well as a heating device for heating at least a flow path of the ink of the first auxiliary ink tank; The ink tank further includes a control unit configured to transfer the ink so that the amount of ink newly supplied from the main ink tank to the first sub-ink tank is greater than the amount of ink remaining in the first sub-ink tank. The ink is a free radical polymerizable ink containing a thermosetting component.

2. The inkjet recording method according to claim 1, wherein The control unit intermittently supplies the ink from the main ink tank to the first sub-ink tank.

3. The inkjet recording method according to claim 1 or 2, wherein Contains blocked isocyanate as the thermosetting component.

4. The inkjet recording method according to any one of claims 1 to 3, wherein further comprising a heating device for heating the flow path of the ink in the second sub-ink tank, Furthermore, the surface area of the inner wall of the ink tank heated by the heating device in the first and second sub-ink tanks, which is in contact with the ink, is larger in the first sub-ink tank than in the second sub-ink tank.

5. The inkjet recording method according to any one of claims 1 to 4, wherein The capacity of the first sub-ink tank is greater than that of the second sub-ink tank.

6. An inkjet recording device that records an image by ejecting ink from an inkjet head, comprising: The main ink tank serves as the ink supply source; a first auxiliary ink tank connected to the main ink tank to supply ink; a degassing device connected to the first auxiliary ink tank, for degassing the ink supplied from the first auxiliary ink tank; a second auxiliary ink tank for supplying the ink degassed by the degassing device to the inkjet head and controlling the negative pressure applied to the inkjet head; as well as a heating device for heating at least a flow path of the ink of the first auxiliary ink tank; The ink tank further includes a control unit configured to transport the ink so that an amount of ink newly supplied from the main ink tank to the first sub ink tank is larger than an amount of ink remaining in the first sub ink tank.

7. The inkjet recording apparatus according to claim 6, wherein The control unit intermittently supplies the ink from the main ink tank to the first sub-ink tank.

Images