Coating device, and method for manufacturing substrate with coating film

Abstract

This coating device comprises: a coating liquid discharge nozzle that has a plurality of coating liquid discharge ports arranged in the width direction of a traveling substrate; and two or more gas discharge nozzles for blowing a gas onto a plurality of columnar jets of a coating fluid discharged from these coating fluid discharge ports. When viewed in the discharge direction of the coating fluid, these two gas discharge nozzles are disposed so that gas discharge ports of the gas discharge nozzles sandwich a row of the plurality of coating liquid discharge ports and the gas discharge ports are located so as to be separated, toward the substrate, from a virtual plane passing through the coating liquid discharge ports and perpendicular to the discharge direction of the coating liquid, and, when viewed in the width direction of the substrate, the angles formed by axes extending from the gas discharge ports in the discharge direction of the gas with axes extending from the coating liquid discharge ports in the discharge direction of the coating liquid are less than 90°.

Description

Coating device and method for producing coated substrate

[0001] The present invention relates to a coating device for applying a coating liquid in droplet form to a substrate such as a film, nonwoven fabric, or paper, and to a method for producing a substrate with a coating film.

[0002] Spray coating devices have been known as coating devices that apply coating liquid to a substrate in the form of droplets. From the viewpoint of productivity and functionality of the substrate, these spray coating devices are required to uniformly apply minute droplets to almost the entire surface of a wide substrate.

[0003] As an example of an application device for such a case, Patent Document 1 discloses a two-fluid slot-type spray nozzle (hereinafter, "spray nozzle" may also be simply referred to as "nozzle") that can spray the coating liquid in droplets by discharging compressed air simultaneously with the coating liquid. This spray nozzle has multiple coating liquid outlets in the width direction of the substrate, and air outlets are arranged so as to sandwich the coating liquid outlets from the upstream and downstream sides in the substrate transport direction. As a result, the ejected droplets of coating liquid form continuous bands in the width direction of the substrate, preventing unevenness in coating thickness and uneven application, and allowing the formation of a uniform coating film.

[0004] Japanese Patent Application Laid-Open No. 2006-026576

[0005] However, in the slot-type spray nozzle disclosed in Patent Document 1, the air outlet is located near the coating liquid outlet, and the discharged air promotes drying of the coating liquid at the coating liquid outlet. If the coating liquid contains solids, the solids may precipitate as the coating liquid dries, causing the coating liquid outlet to clog or its opening area to decrease due to the precipitated solids. If the coating liquid outlet becomes clogged or its opening area decreases, continuous streaks of coating voids or areas of thin coating film thickness may form in the conveyance direction at the coating position corresponding to the clogged area. Furthermore, in a slot-type spray nozzle, the coating liquid outlet and the air outlet are located at the same height and on approximately the same plane, so the coating liquid at the coating liquid outlet may wet and spread, reaching the air outlet and drying there. If the coating liquid contains solids, the solids may precipitate as the coating liquid dries, causing the air outlet to clog or its opening area to decrease. If an air outlet becomes clogged or its opening area becomes small, the air necessary to turn the coating liquid into droplets is not supplied to that location even when the coating liquid is ejected, causing problems such as the coating liquid not being ejected sufficiently, resulting in uneven coating, or the coating liquid that is not ejected collecting near the coating liquid outlet and then dropping onto the substrate, significantly deteriorating the coating appearance. Furthermore, if the coating liquid contains a low-boiling point organic solvent or the like, the coating liquid dries quickly, and clogging of the coating liquid outlet and air outlet due to precipitation of solids becomes an even more serious problem.

[0006] As described above, in a coating device that applies a coating liquid in droplet form to a substrate such as a film, nonwoven fabric, or paper, no spray coating device has been found that applies a coating liquid while suppressing clogging of the coating liquid discharge port and air discharge port due to drying of the coating liquid, even when a coating liquid containing solids is used.

[0007] Therefore, the present invention provides a spray coating device and a method for producing a coated substrate that can prevent clogging of the coating liquid discharge port and air discharge port due to drying of the coating liquid.

[0008] [1] The present invention, which solves the above problem, is a coating device that coats a traveling substrate with droplet-like coating liquid, comprising: a coating liquid discharge nozzle having a plurality of coating liquid discharge ports arranged in the width direction of the substrate; and at least two gas discharge nozzles for blowing gas onto the plurality of columnar coating liquid discharged from the coating liquid discharge ports, wherein, when observed from the coating liquid discharge direction, the two gas discharge nozzles have their respective gas discharge ports sandwiching a row of the plurality of coating liquid discharge ports, and the gas discharge ports are arranged so as to be located farther toward the substrate than an imaginary plane that passes through the coating liquid discharge ports and is perpendicular to the coating liquid discharge direction, and wherein, when observed from the width direction of the substrate, an axis extending from the gas discharge port in the gas discharge direction forms an angle of less than 90° with an axis extending from the coating liquid discharge port in the coating liquid discharge direction.

[0009] The coating device of the present invention is preferably in the following aspect [2] or [3]: [2] The coating device of the above [1], wherein the gas discharge nozzle can change the discharge direction of the gas from the gas discharge port when observed from the width direction of the substrate.

[0010] [3] The coating device of [1] or [2] above, wherein, when the coating device is observed from the width direction of the substrate, the distance from the intersection of an axis extending in the coating liquid discharge direction from the coating liquid discharge port and an axis extending in the gas discharge direction from the gas discharge port to the coating liquid discharge port is 2 mm or more. [4] A method for producing a substrate with a coated film of the present invention that solves the above problem comprises: discharging coating liquid toward a traveling substrate from a plurality of coating liquid discharge ports arranged in the width direction of the substrate; blowing gas toward the coating liquid at a position away from the coating liquid discharge port toward the substrate from a direction that is symmetrical to the discharged coating liquid and forms an angle of less than 90° with the coating liquid discharge direction when observed from the width direction of the traveling substrate; and applying droplets of the coating liquid to the substrate.

[0011] The method for producing a substrate with a coating film of the present invention preferably involves any one of the following [5] to [7]. [5] The method for producing a substrate with a coating film of the above [4], wherein the distance from the position where the gas is blown in the coating liquid to the coating liquid discharge port is 2 mm or more. [6] The method for producing a substrate with a coating film of the above [4] or [5], wherein the coating liquid contains a solid content. [7] The method for producing a substrate with a coating film of any one of the above [4] to [6], wherein the solvent in the coating liquid is an organic solvent.

[0012] By using the coating device of the present invention, clogging of the coating liquid discharge port and the air discharge port due to drying of the coating liquid can be prevented, and the coating liquid can be applied stably.

[0013] FIG. 1 is a schematic cross-sectional view of a coating apparatus 100 of the present invention. FIG. 2 is an exploded perspective view showing the configuration of the coating liquid discharge nozzle 110 of FIG. 1. FIG. 3 is an exploded perspective view showing the configuration of the gas discharge nozzle 120 of FIG. 1. FIG. 4 is a schematic cross-sectional view of the coating apparatus 100 of the present invention and a view showing the state during coating film formation using the coating apparatus 100. FIG. 5 is a bottom view of the tip of the coating liquid discharge nozzle 110 of FIG. 1, viewed from the coating liquid discharge port side. FIG. 6 is an exploded perspective view showing the configuration of a coating liquid discharge nozzle 210 according to another embodiment of the coating liquid discharge nozzle. FIG. 7 is a bottom view of the tip of the gas discharge nozzle 120 of FIG. 1, viewed from the gas discharge port side. FIG. 8 is an exploded perspective view showing the configuration of a gas discharge nozzle 220 according to another embodiment of the gas discharge nozzle. FIG. 9 is a schematic view showing an apparatus 10 for producing a coated substrate of the present invention. FIG. 10 is a schematic cross-sectional view of a conventional integrated two-fluid nozzle 300.

[0014] The preferred embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments shown in the drawings, and various modifications are possible within the scope of the invention, which can achieve the object of the invention and does not deviate from the gist of the invention.

[0015] Please refer to Fig. 1. Fig. 1 is a schematic cross-sectional view of a coating apparatus 100 according to a first embodiment of the present invention. The coating apparatus 100 is composed of a coating liquid discharge nozzle 110 for discharging a coating liquid and gas discharge nozzles 120, 120' for discharging a gas.

[0016] Please refer to FIG. 2. FIG. 2 is an exploded perspective view showing the configuration of the coating fluid discharge nozzle 110 of FIG. 1. The coating fluid discharge nozzle 110 is composed of coating fluid nozzle blocks 111 and 112 and a coating fluid shim 113. One of the coating fluid nozzle blocks, 111, has a coating fluid supply port 114 that supplies the coating fluid into the coating fluid discharge nozzle 110, and a coating fluid manifold 115 that communicates with the coating fluid supply port 114 and spreads the coating fluid in the width direction. The coating fluid shim 113 is a comb-shaped shim sandwiched between the coating fluid nozzle blocks 111 and 112. When combined with the coating fluid nozzle blocks 111 and 112, the gaps between the comb teeth of the coating fluid shim 113 form multiple coating fluid flow paths in the width direction. The gaps between the comb teeth of the coating fluid shim 113 also communicate with the coating fluid manifold 115. The "width direction" corresponds to the direction perpendicular to the discharge direction X of the coating fluid and the transport direction Y of the substrate 1 (see FIG. 1).

[0017] Please refer to FIG. 3. FIG. 3 is an exploded perspective view showing the configuration of the gas discharge nozzle 120 in FIG. 1, and the gas discharge nozzle 120' in FIG. 1 has a similar configuration. The gas discharge nozzle 120 is composed of gas nozzle blocks 121 and 122 and a gas shim 123. One of the gas nozzle blocks, 121, has a gas supply port 124 that supplies gas into the gas discharge nozzle 120, and a gas manifold 125 that communicates with the gas supply port 124 and spreads the gas in the width direction. The gas shim 123 is a U-shaped shim, and is sandwiched between the gas nozzle blocks 121 and 122 to form a slit-shaped gas flow path in the width direction. In this case, the gas flow path of the gas shim 123 communicates with the gas manifold 125.

[0018] Referring again to FIG. 1 , the coating liquid is discharged from coating liquid outlets 116 located at the tip of the coating liquid discharge nozzle 110 and aligned in a row in the width direction. The gas is discharged from gas outlets 126, 126' located at the tips of the gas discharge nozzles 120, 120'. When observed from the coating liquid discharge direction X, the gas discharge nozzles 120, 120' are arranged such that the gas outlets 126, 126' are positioned on either side of the row of coating liquid outlets 116 of the coating liquid discharge nozzle 110, and the gas outlets 126, 126' are positioned further away in the coating liquid discharge direction X than an imaginary plane A that passes through the coating liquid outlets 116 and is perpendicular to the coating liquid discharge direction X. In this case, the gas outlets 126, 126' are positioned closer to the substrate 1 than the imaginary plane A. Here, the coating device 100 is installed at a certain distance from the substrate 1, and the coating liquid discharge port 116 of the coating liquid discharge nozzle 110 is arranged so that an extension line of the discharge direction X of the coating liquid intersects with the substrate 1. The coating liquid discharge nozzle 110 and the gas discharge nozzles 120, 120′ extend in the short direction of the substrate 1, i.e., in a direction perpendicular to the transport direction Y of the substrate 1.

[0019] Please refer to FIG. 4. FIG. 4 is a schematic cross-sectional view of a coating apparatus 100 of the present invention and a diagram illustrating the application of a coating liquid to a substrate using the coating apparatus 100. First, a coating liquid 2 supplied to a coating liquid discharge nozzle 110 is discharged from a plurality of coating liquid discharge ports 116 provided at the tip of the coating liquid discharge nozzle 110, and the discharged coating liquid is continuously connected to form a columnar coating liquid 3. Next, the columnar coating liquid 3 collides with gas discharged from gas discharge ports 126, 126' provided at the tip of the gas discharge nozzles 120, 120' at collision point B, forming fine droplets 4. Collision point B is the intersection of an axis extending from the coating liquid discharge port 116 in the coating liquid discharge direction X and an axis extending from the gas discharge ports 126, 126' in the gas discharge direction. The fine droplets 4 land on the substrate 1 being transported, forming a coating film 5. Here, because gas outlets 126, 126' are located away from imaginary plane A in coating liquid discharge direction X, the gas discharged from gas outlets 126, 126' does not hit coating liquid discharge nozzle 110 and is not attenuated, and furthermore, the discharged gas does not hit coating liquid discharge outlet 116 directly. In other words, drying of the coating liquid at coating liquid discharge outlet 116 can be suppressed. At this time, the gas discharged from gas outlets 126, 126' diffuses as it moves away from gas outlets 126, 126'. Therefore, it is preferable that distance L1 between coating liquid discharge outlet 116 and collision point B be 2 mm or more so that the gas is not blown directly at coating liquid discharge outlet 116. Since the coating liquid discharge nozzle 110 having the coating liquid discharge port 116 and the gas discharge nozzles 120, 120' having the gas discharge ports 126, 126' are arranged independently of each other, even if the coating liquid spreads wet from the coating liquid discharge port 116, the coating liquid will not reach the gas discharge ports 126, 126' and the coating liquid will not dry at the gas discharge ports 126, 126'.

[0020] Furthermore, in order to prevent the coating liquid pillars 3 discharged from the coating liquid discharge nozzle 110 from adhering to the gas discharge ports 126, 126', the distances L2, L2' between the gas discharge ports 126, 126' and the collision point B are preferably 2 mm or more. Furthermore, in order to turn the coating liquid pillars 3 into fine droplets 4, it is necessary to discharge gas from the gas discharge nozzles 120, 120' at high speed so that the gas collides with the coating liquid pillars 3 at the collision point B. Therefore, in order to turn the coating liquid pillars into fine droplets 4, it is more preferable that the distances L2, L2' be 10 mm or less.

[0021] In order to eject the coating liquid 2 in a pillar shape from the coating liquid ejection ports 116, it is necessary to eject the coating liquid 2 vigorously from each coating liquid ejection port 116, and the ejection amount can be adjusted appropriately depending on the type and viscosity of the coating liquid 2. As a result of extensive studies by the inventors, it has been found that the average flow velocity of the coating liquid 2 within the comb-shaped coating liquid flow path inside the coating liquid ejection nozzle 110 is preferably 2 m / s or more, and more preferably 5 m / s or more in order to stabilize the shape of the coating liquid pillar 3 after ejection, regardless of the type or viscosity of the coating liquid 2.

[0022] On the other hand, in order to turn the pillar-shaped coating liquid 3 into fine droplets 4, it is necessary to eject the gas from the gas ejection ports 126, 126' with great force. As a result of extensive investigations by the inventors, it has been found that it is preferable to set the average flow velocity of the gas in the slit-shaped gas flow path inside the gas ejection nozzles 120, 120' to 100 m / s or more. Furthermore, in anticipation of a case in which the shape of the pillar-shaped coating liquid 3 is not stable, such as immediately after the start of ejection of the coating liquid, the gas ejection nozzles 120, 120' may be provided with a retraction mechanism.

[0023] Furthermore, the gas discharge nozzles 120, 120' are installed so that the gas discharge direction can be changed as desired, and the angles θ, θ' (hereinafter referred to as "impingement angles θ, θ'") between the discharge direction X of the coating liquid discharged from the coating liquid discharge port 116 and the axis extending in the gas discharge direction from the gas discharge port 126, 126' can be changed as desired. In order for the droplets 4 atomized at the collision point B to fly toward the substrate 1 and land on the substrate 1, the collision angles θ, θ' must be less than 90°. Furthermore, since the collision angles θ, θ' affect the size of the droplets that land on the substrate 1, they can be changed appropriately; increasing the collision angles θ, θ' reduces the droplet size, while decreasing the collision angles θ, θ' increases the droplet size.

[0024] Furthermore, the gas discharge nozzles 120, 120' do not need to be installed symmetrically with respect to the discharge direction X of the coating liquid discharged from the coating liquid discharge port 116, and the gas discharge nozzles 120, 120' may be installed so as to be asymmetrical with respect to the coating liquid discharge nozzle 110. In other words, the gas discharged from the gas discharge nozzles 120, 120' may have collision points B, B' with the columnar coating liquid 3, respectively, and the distances L2, L2' and the collision angles θ, θ' can be changed as desired.

[0025] Please refer to FIG. 5. FIG. 5 is a bottom view of the coating fluid discharge nozzle 110 of FIG. 1, as viewed from the coating fluid discharge port side. The coating fluid discharge ports 116 of the coating fluid discharge nozzle 110 are rectangular openings, and a plurality of them are arranged at a predetermined interval W1 (hereinafter referred to as the "arrangement pitch") along the longitudinal direction of the coating fluid discharge nozzle 110. The total width of all the coating fluid discharge ports 116 is a coating fluid discharge width W2. At this time, the width of the coating film that can be formed on the substrate 1 is approximately the same as the coating fluid discharge width W2. The opening width W3 of each coating fluid discharge port 116 is preferably 50 μm or more so that the rate of change in opening area is small even if processing variations of about 5 μm occur between the respective discharge ports. Furthermore, the thickness t1 of the coating fluid shim 113 is preferably 50 μm or more so that the rate of change in opening area is small even if shim thickness variations of about 5 μm occur. The opening area of ​​each coating liquid discharge port 116 may be adjusted as appropriate depending on the viscosity of the coating liquid used and the flow rate of the coating liquid to be discharged. However, in order to ensure that the coating liquid discharged from the coating liquid discharge port 116 has a constant flow rate and is discharged in a columnar shape, the opening area of ​​50,000 μm ２ It is preferable to set the average flow velocity to 20,000 μm or less so that the average flow velocity does not decrease. ２ It is more preferable that the arrangement pitch W1 of the coating liquid discharge ports is 10 mm or less from the viewpoint of coating film uniformity. Furthermore, it is preferable that the coating liquid discharge width W2 is smaller than the substrate width in order to minimize scattering of the coating liquid outside the system.

[0026] Please refer to Figure 6. Figure 6 is an exploded perspective view showing the configuration of a coating liquid discharging nozzle 210 according to another embodiment of the coating liquid discharging nozzle. The coating liquid discharging nozzle 210 is composed of coating liquid nozzle blocks 211 and 212. One of the coating liquid nozzle blocks, 211, has a coating liquid supply port 214 that supplies the coating liquid into the interior of the coating liquid discharging nozzle 210. The other coating liquid nozzle block 212 has a coating liquid manifold 215 for spreading the coating liquid in the width direction and a coating liquid discharging flow path 217 that communicates with the coating liquid manifold 215, and a coating liquid discharging outlet 216 is formed at the tip of the coating liquid discharging flow path 217. The shape of the coating liquid discharging outlet 216 is not limited to rectangular, and may be circular or elliptical.

[0027] Refer to FIG. 7. FIG. 7 is a bottom view of the gas discharge nozzle 120 of FIG. 1, showing the tip of the gas discharge nozzle 120 as viewed from the gas discharge port side. The gas discharge port 126 of the gas discharge nozzle 120 is slit-shaped, and the width of the gas discharge port 126 is the gas discharge width W4. Here, the two-dot chain lines indicated by the reference symbols 116L and 116R indicate the positions of both ends of the coating liquid discharge width W2 in the coating liquid discharge nozzle 110. The gas discharge width W4 is longer than the coating liquid discharge width W2 in order to convert all of the columnar coating liquid 3 discharged from each coating liquid discharge port 116 into fine droplets 4. Note that the shape of the gas discharge port 126 is not limited to a single slit continuous across the width direction as shown in FIGS. 3 and 7, but may be intermittently opened in the width direction so as to correspond one-to-one to the coating liquid discharge ports 116. When the gas discharge port 126 is opened intermittently, it is preferable that the opening length in the width direction be greater than the width W3 of each coating liquid discharge port 116.

[0028] Please refer to Figure 8. Figure 8 is an exploded perspective view showing the configuration of a gas discharge nozzle 220 according to another embodiment of the gas discharge nozzle. The gas discharge nozzle 220 is composed of gas nozzle blocks 221 and 222. One of the gas nozzle blocks, 221, has a gas supply port 224 that supplies gas into the gas discharge nozzle 220. The other gas nozzle block 222 has a gas manifold 225 for expanding the gas in the width direction and a gas discharge flow path 227 that communicates with the gas manifold 225, and a gas discharge port 226 is formed at the tip of the gas discharge flow path 227. The shape of the gas discharge port 226 is not limited to rectangular, and may be circular or elliptical.

[0029] As described above, by using the spray coating device according to the present invention, even when a coating liquid containing solids is discharged, the coating liquid can be stably applied without clogging the coating liquid discharge port and the gas discharge port.

[0030] Next, a coated substrate manufacturing apparatus 10 for manufacturing a coated substrate using the coating apparatus 100 of the present invention will be described with reference to Figure 9. Figure 9 is a schematic diagram showing an example of the coated substrate manufacturing apparatus 10 of the present invention.

[0031] The coated substrate manufacturing apparatus 10 includes an unwinding section 11 that unwinds the substrate 1 and a winding section 12 that winds the coated substrate 6. Between the unwinding section 11 and the winding section 12, there are provided a coating device 100 for applying a coating liquid to the substrate 1 and a drying device 13 for drying the coating. In addition, to prevent the substrate 1 from vibrating due to the gas discharged from the coating device 100 and the distance between the coating device 100 and the substrate 1 from changing over time, a backup roll 14 is provided on the opposite side of the coating device 100 across the substrate 1, and contacts and supports the substrate 1. By having the substrate 1 embraced by the backup roll 14, it is possible to prevent the backup roll 14 from rotating as the substrate 1 is transported, and thus prevent the substrate 1 from slipping on the backup roll 14 and being damaged. Furthermore, the coating liquid discharge mechanism includes a liquid supply pump 15 for supplying the coating liquid to the coating device 100 and a tank 16 for storing the coating liquid, and the gas discharge mechanism includes a pressurized gas source 17 for supplying gas to the coating device 100, a branch pipe 18 that branches the gas to each gas discharge nozzle, and pressure adjustment valves 19, 19' that can adjust the pressure of the gas supplied from each gas discharge nozzle. The coating device 100 and the backup roll 14 are surrounded by a booth 20, and the booth 20 has an opening 21 at its bottom that communicates with a waste liquid recovery tank 22.

[0032] The booth 20 prevents some of the fine droplets 4 formed by the coating device 100 from scattering around without adhering to the substrate 1. The coating liquid adhering to the inner wall of the booth 20 drips down along the inner wall of the booth 20 and is collected in a waste liquid recovery tank 22 through a bottom opening 21. Since the booth 20 and the waste liquid recovery tank 22 come into contact with the coating liquid, it is preferable to select materials depending on the coating liquid. For example, when the solvent of the coating liquid is acetone, which is a low-boiling organic solvent, it is preferable to use a metal or a resin material with excellent acetone resistance, such as a fluororesin.

[0033] In the coated substrate manufacturing apparatus 10 shown in Figure 9, the coating liquid is ejected in a vertically downward direction from the coating device 100, and the transport direction of the substrate 1 in that section is horizontal. However, this is not limited to this as long as the coating device 100 is installed so as to be approximately opposite the coating surface of the substrate 1. For example, the coating liquid may be ejected in a horizontal direction from the coating device 100, and the transport direction of the section may be vertical.

[0034] Next, a method for producing a substrate with a coating film using the coating apparatus 100 of the present invention will be described again with reference to FIG. 4 . The substrate with a coating film is produced by forming a coating film 5 on a substrate 1 using the coating apparatus 100. At this time, the basis weight of the coating film 5 can be controlled by the flow rate of the coating liquid 2 supplied to the coating liquid discharge nozzle 110, so it is preferable to have a means for measuring the basis weight of the formed coating film 5 and adjusting the supply flow rate of the coating liquid 2. Furthermore, the size of the deposited droplets is determined by the flow rate of the gas supplied to the gas discharge nozzles 120 and 120′ and the collision angles θ and θ′. To reduce the droplet size, the flow rate of the gas supplied to the gas discharge nozzles 120 and 120′ can be increased, or the collision angles θ and θ′ can be increased. On the other hand, to increase the droplet size, the droplet size can be adjusted by reducing the flow rate of the gas supplied to the gas discharge nozzles 120 and 120′ or reducing the collision angles θ and θ′.

[0035] Furthermore, immediately after the coating liquid is discharged, the discharge pressure of the coating liquid 2 discharged from the coating liquid discharge port 116 of the coating liquid discharge nozzle 110 is low, and the shape of the coating liquid pillar 3 may not be stable until the discharge pressure increases to a predetermined level. Therefore, it is preferable to retract the gas supply nozzles 120, 120' to prevent the coating liquid from scattering at the gas supply nozzles 120, 120' until a stable coating liquid pillar 3 is formed. Thereafter, after the shape of the coating liquid pillar 3 has stabilized, the gas discharge nozzles 120, 120' are brought close to the coating liquid pillar 3, and gas is discharged from the gas discharge ports 126, 126'. This prevents the coating liquid 2 from adhering to the gas discharge ports 126, 126', enabling stable coating without clogging the gas discharge ports 126, 126'.

[0036] The coating device of the present invention is particularly effective for coating liquids containing solids, such as solutions of inorganic or organic substances or dispersions of inorganic or organic substances in a solvent. The viscosity of the coating liquid may be any viscosity as long as it can be atomized by the impact of the discharged gas. The lower the viscosity, the more fine droplets can be formed. A viscosity of 500 mPa·s or less generally results in a good coating appearance. A viscosity of 2.0 mPa·s or less is particularly preferred.

[0037] The effects of the present invention can be particularly obtained when the coating liquid contains an organic solvent as part of the solvent, and are particularly effective when the coating liquid contains at least one low-boiling organic solvent having a boiling point of 100° C. or less, such as acetaldehyde, acetone, acetonitrile, allyl alcohol, benzene, 2-butanol, methyl ethyl ketone, tert-butyl alcohol, carbon disulfide, chloroform, cyclohexane, 1,2-dichloroethane, dichloromethane, diethyl ether, ethanol, absolute ethanol, ethyl acetate, 1,2-dimethoxyethane, ethyl formate, ethyl propionate, heptane, hexane, ligroin, methanol, methyl acetate, methyl propionate, pentane, petroleum benzine, 1-propanol, propylene oxide, n-propyl ether, tetrahydrofuran, trichloroethylene, triethylamine, or trifluoroacetic acid.

[0038] The gas components of the gas and ambient air used in the present invention are not particularly limited as long as they are suitable for coating, and air, nitrogen gas, etc. can be used. The ambient pressure of the ambient air is not particularly limited, and it can be an atmospheric pressure environment or a reduced pressure environment. In addition, there are no particular limitations on the temperature of the gas or ambient air, but using hot air as the gas promotes drying of fine droplets in flight. This not only allows for the formation of finer droplets, but also reduces the amount of moisture adhering to the substrate, thereby reducing the drying load in subsequent processes.

[0039] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0040] <Coating Liquid> A coating liquid was prepared by preparing polyvinylidene fluoride, a fluororesin, as the solid content and acetone (boiling point 56°C), a low-boiling organic solvent, as the solvent, and blending them so that the solid content concentration was 5 wt %.

[0041] Example 1 A coated substrate 6 was produced by mounting the coating device 100 shown in FIG. 1 on a coated substrate manufacturing apparatus 10 shown in FIG. 9 . A coating film was formed on a substrate 1 unwound from an unwinding section 11 using the coating device 100. The coating film was completely dried in a drying device 13, and then the coated substrate 6 was wound up in a winding section 12. The wound coated substrate 6 was then removed, and the presence or absence of droplets and the coating appearance were evaluated by visual and microscope observation. The coating conditions for the coating device 100 were as follows: a distance from an imaginary plane A passing through the coating liquid discharge port 116 to the gas discharge ports 126, 126′ was 7.5 mm; a distance L1 between the coating liquid discharge port 116 and the collision point B was 10 mm; distances L2, L2′ between the gas discharge ports 126, 126′ and the collision point B were 5 mm; and collision angles θ, θ′ were 60° (see FIG. 4 ). The coating liquid discharge nozzle 110 had a coating liquid discharge width W2 of 210.1 mm, a coating liquid discharge port opening width W3 of 100 μm, a coating liquid shim thickness t1 of 100 μm, and an arrangement pitch W1 of the coating liquid discharge ports of 7.5 mm. In this case, the number of coating liquid discharge ports 116 was 29 (see FIG. 5). The gas discharge nozzles 120 and 120′ had a gas discharge width W4 of 250 mm and a gas shim thickness of 50 μm (see FIG. 7). The coating procedure involved transporting the substrate 1 at a speed of 50 m / min, discharging the coating liquid from the coating liquid discharge nozzle 110 at 100 mL / min, and discharging compressed air from each of the gas discharge nozzles 120 and 120′ at 300 L / min.

[0042] Example 2 Coating was carried out on the substrate 1 under the same conditions as in Example 1, except that the collision angles θ and θ′ were set to 30°.

[0043] Example 3 Coating was carried out on the substrate 1 under the same conditions as in Example 1, except that the distance L1 between the coating liquid discharge port 116 and the collision point B was set to 2 mm, and the collision angles θ and θ′ were set to 80°.

[0044] Comparative Example 1 Coating was carried out on the substrate 1 under the same conditions as in Example 1, except that the distance L1 between the coating liquid discharge port 116 and the collision point B was set to 0.5 mm. In Comparative Example 1, in relation to the distance L1, the gas discharge ports 126, 126' are located on the opposite side from the substrate 1 side of the imaginary plane A. In other words, the gas discharge ports 126, 126' according to Comparative Example 1 are located closer to the coating liquid discharge nozzle 110 than the imaginary plane A.

[0045] Comparative Example 2 Coating was carried out on the substrate 1 under the same conditions as in Example 1, except that the collision angles θ and θ′ were set to 90°.

[0046] Comparative Example 3 Coating was performed on a substrate 1 using a conventional integrated two-fluid nozzle 300 shown in FIG. 10 . The integrated two-fluid nozzle 300 has its longitudinal direction perpendicular to the transport direction Y of the substrate 1, i.e., the width direction of the substrate 1 (the direction perpendicular to the paper surface), and is installed facing the substrate 1 at a certain distance from the substrate 1. The integrated two-fluid nozzle 300 is composed of outer die blocks 301, 301′ and inner die blocks 302, 302′. The coating fluid is supplied to a coating fluid pocket 303 and discharged from a coating fluid discharge port 304, while the gas is supplied to gas pockets 305, 305′ and discharged from gas discharge ports 306, 306′. The gas discharge ports 306, 306′ are positioned on either side of the coating fluid discharge port 304 when viewed from the direction of coating fluid discharge. The coating fluid discharge port 304 and the gas discharge ports 306, 306′ are on the same plane. Using this integrated two-fluid nozzle 300, coating was carried out on the substrate 1 in the same procedure as in Example 1.

[0047] <Evaluation Method> In the above examples and comparative examples, coating was carried out continuously for 30 minutes. Evaluation of the coating state was carried out using the substrate 6 with a coating film wound up by the winding section 12. The evaluation results are shown in Tables 1 and 2. The droplet adhesion status in the tables was determined based on the droplet adhesion rate to the substrate. The droplet adhesion rate to the substrate was derived by measuring the basis weight of the substrate with a coating film and the substrate before coating, calculating the basis weight of the coating film formed on the substrate, and then calculating the ratio of that basis weight to the total solids contained in the coating liquid supplied to the coating liquid discharge nozzle. The droplet adhesion status was evaluated as "○" if the basis weight was 30% or more of the total solids, and "×" if it was less than 30%. The average particle size of the droplets was measured using a laser diffraction particle size analyzer (FLD-319A, manufactured by Seika Digital Image Co., Ltd.) for the droplets flying just before they adhered to the substrate. The average particle size shown here refers to the Sauter mean diameter. Furthermore, to check the clogging status of the coating liquid discharge port 116 during the coating operation, a pressure gauge (not shown) was installed in communication with the coating liquid manifold 115, and the pressure inside the coating liquid manifold was measured 15 minutes and 30 minutes after the start of coating. Regarding the coating appearance, "missing coating" refers to a streak-like missing coating area that occurs in the substrate conveyance direction, and "uneven coating" refers to a linear appearance unevenness that occurs in the substrate conveyance direction, representing coating unevenness caused by differences in the rate of liquid adhesion to the substrate. Furthermore, to evaluate clogging of the coating liquid discharge port and the gas discharge port, the tip of each discharge nozzle was observed after 30 minutes of continuous coating, and if even partial clogging was observed, it was judged to have occurred. In all examples and comparative examples, the appearance of the coating film was good immediately after the start of coating, and the pressure inside the coating liquid manifold was 0.1 MPa.

[0048]

[0049]

[0050] Comparison of Example 1 and Comparative Example 3 In the conventional integrated two-fluid nozzle 300 described in Comparative Example 3, solids of the coating liquid precipitated at both the coating liquid outlet 304 and the gas outlets 306 and 306' 30 minutes after the start of coating, and clogging was confirmed at each outlet. This resulted in streaky coating-missing areas and linear coating irregularities on the coated substrate. Furthermore, the pressure in the coating liquid manifold rose to 0.2 MPa 15 minutes after the start of coating. When the coating liquid outlet is clogged, the opening area of ​​the coating liquid outlet becomes smaller, and thus, if the liquid supply pump continues to deliver a fixed amount of coating liquid, the pressure inside the coating liquid manifold increases. In other words, it was confirmed that a portion of the coating liquid outlet 304 was clogged within a short period of time, up to 15 minutes after the start of coating. On the other hand, in Example 1, even 30 minutes after the start of coating, the pressure inside the coating liquid manifold did not increase, and no blockage of the coating liquid outlet 116 or the gas outlets 126, 126' was observed, and a coating film 5 with a good coating appearance was formed.

[0051] Comparison of Example 1 and Example 2 In Example 2, it was confirmed that by reducing the collision angles θ and θ', the average particle size of the droplets became larger compared to Example 1. That is, it was confirmed that by changing the collision angles θ and θ', the force of collision with the columnar coating liquid 3 could be controlled, and the average particle size of the droplets could be changed to a desired size. Furthermore, in both Examples 1 and 2, even 30 minutes after the start of coating, the pressure inside the coating liquid manifold did not increase, and no blockage of the coating liquid discharge port 116 and the gas discharge ports 126 and 126' was observed, and a coating film 5 with a good coating appearance could be formed.

[0052] Comparison of Example 1 and Example 3 In Example 3, the distance L1 between the coating liquid discharge port and the collision point was set to 2 mm, and the collision angles θ and θ' were set to 80° so that the gas discharge ports 126 and 126' were located away from the imaginary plane A toward the substrate 1. It was confirmed that the average particle size of the droplets was reduced by increasing the collision angles θ and θ' compared to Example 1. Furthermore, in both Examples 1 and 3, even 30 minutes after the start of coating, the pressure inside the coating liquid manifold did not increase, and no blockage of the coating liquid discharge port 116 or the gas discharge ports 126 and 126' was observed, and a coating film 5 with a good coating appearance was formed.

[0053] Comparison of Example 1 and Comparative Example 1 In Comparative Example 1, the gas discharge ports 126, 126' are located on the opposite side from the substrate 1 side with respect to the imaginary plane A. The gas discharged from the gas discharge ports 126, 126' hits the coating liquid discharge nozzle 110 and does not hit the coating liquid pillar 3, so that no fine droplets 4 are formed. Thereafter, in order to make the gas discharged from the gas discharge ports 126, 126' hit the coating liquid pillar 3, the collision angles θ, θ' were adjusted while the positions of the gas discharge ports 126, 126' were fixed. However, in the range of L2≦10 mm, no fine droplets 4 could be formed, and in the range of L2>10 mm, the gas colliding with the coating liquid pillar 3 was attenuated, making it impossible to form fine droplets 4.

[0054] [Comparison between Example 1 and Comparative Example 2] In Comparative Example 2, the collision angles θ and θ' were 90°. Therefore, the droplets 4 atomized at collision point B did not head toward the substrate 1, resulting in a significant drop in droplet adhesion rate to 10%. In addition, some of the minute droplets 4 headed toward the coating liquid discharge port 116 precipitated at the coating liquid discharge port 116, causing a portion of the coating liquid discharge port 116 to become clogged.

[0055] The present invention can be applied to a coating device that forms a coating film on a substrate film such as resin, paper, thin metal film, or cloth, and to a manufacturing device and manufacturing method for a coated substrate that is equipped with such a coating device, but is not limited to this.

[0056] REFERENCE SIGNS LIST 1 Substrate 2 Coating liquid 3 Columnar coating liquid 4 Fine droplets 5 Coating film 6 Coated substrate 10 Apparatus for manufacturing coated substrate 11 Unwinding section 12 Winding section 13 Drying device 14 Backup roll 15 Liquid supply pump 16 Tank 17 Pressurized gas source 18 Branch pipe 19, 19' Pressure adjustment valve 20 Booth 21 Bottom opening 22 Waste liquid recovery tank 100 Coating device 110 Coating liquid discharge nozzle 111, 112 Coating liquid nozzle block 113 Coating liquid shim 114 Coating liquid supply port 115 Coating liquid manifold 116 Coating liquid discharge port 120, 120' Gas discharge nozzle 121, 122 Gas nozzle block 123 Gas shim 124 Gas supply port 125, 125' Gas manifold 126, 126' Gas outlet 210 Coating fluid outlet nozzle 211, 212 Coating fluid nozzle block 214 Coating fluid supply port 215 Coating fluid manifold 216 Coating fluid outlet 217 Coating fluid outlet flow path 220 Gas outlet nozzle 221, 222 Gas nozzle block 224 Gas supply port 225 Gas manifold 226 Gas outlet 227 Gas outlet flow path 300 Integrated two-fluid nozzle 301, 301' Outer die block 302, 302' Inner die block 303 Coating fluid pocket 304 Coating fluid outlet 305, 305' Gas pocket 306, 306' Gas outlet A Virtual surface B, B' Collision point L1 Distance between coating fluid outlet and collision point: L2, L2' Distance between gas outlet and collision point: t1 Thickness of coating fluid shim: W1 Array pitch of coating fluid outlets: W2 Coating fluid outlet width: W3 Opening width of each coating fluid outlet: W4 Gas outlet width: X Coating fluid outlet direction: Y Direction of substrate transport: θ, θ' Collision angle:

Claims

1. A coating device which coats a traveling substrate with droplets of a coating liquid, comprising: a coating liquid discharge nozzle having a plurality of coating liquid discharge ports arranged in the width direction of the substrate; and at least two gas discharge nozzles for blowing gas onto a plurality of columnar coating liquid discharged from the coating liquid discharge ports, wherein the two gas discharge nozzles are arranged such that, when observed from the coating liquid discharge direction, each gas discharge port sandwiches a row of the plurality of coating liquid discharge ports, and the gas discharge ports are arranged so as to be located further towards the substrate than an imaginary plane that passes through the coating liquid discharge port and is perpendicular to the coating liquid discharge direction, and wherein, when observed from the width direction of the substrate, an angle between an axis extending from the gas discharge port in the gas discharge direction and an axis extending from the coating liquid discharge port in the coating liquid discharge direction is less than 90°.

2. The coating device according to claim 1, wherein the gas discharge nozzle is provided so as to be capable of changing the direction in which the gas is discharged from the gas discharge port as observed from the width direction of the substrate.

3. A coating device according to claim 1 or 2, wherein, when the coating device is observed in the width direction of the substrate, the distance from the intersection of an axis extending from the coating liquid outlet in the coating liquid outlet direction and an axis extending from the gas outlet in the gas outlet direction to the coating liquid outlet is 2 mm or more.

4. A method for manufacturing a substrate with a coating film, comprising the steps of: ejecting a coating liquid from a plurality of coating liquid ejection ports arranged in the width direction of the substrate toward a traveling substrate; blowing gas toward the coating liquid at a position away from the coating liquid ejection port toward the substrate from a direction that is symmetrical to the ejected coating liquid and forms an angle of less than 90° with the ejection direction of the coating liquid when observed from the width direction of the traveling substrate; and applying droplets of the coating liquid to the substrate.

5. The method for producing a substrate with a coating film according to claim 4, wherein the distance from the position in the coating liquid where the gas is blown to the coating liquid discharge port is 2 mm or more.

6. The method for producing a substrate having a coating film according to claim 4 or 5, wherein the coating liquid contains solids.

7. The method for producing a substrate with a coating film according to claim 4 or 5, wherein the solvent for the coating liquid is an organic solvent.

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