JP2007075677A - Curtain spray coating method for surface layer, curtain spray coating device for surface layer coating, inkjet recording paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a coating liquid on at least one ink absorbing layer formed on a support by a curtain spray coating device to form a surface layer to produce a recording paper, a droplet during coating. Coating method for surface layer, curtain spray coating device for surface layer coating, and recording paper that can be applied safely for a long period of time by preventing coating failure due to falling.
In a curtain spray coating method for a surface layer of an ink jet recording paper in which a surface layer is formed by a curtain spray coating device on an ink absorbing layer on a support, the curtain spray coating device includes a coater, a scattering coating liquid, and the like. The splash coating liquid recovery device has a housing structure including a side plate having a suction port, a top plate having a gas intake port, and a bottom plate, and has a recovery device and a moving means. A curtain spray coating method for a surface layer, wherein the coating is performed while reducing the pressure inside the housing and taking in gas from the gas inlet.
[Selection] Figure 1

Description

  The present invention relates to a surface layer of an ink jet recording paper (hereinafter also referred to simply as a recording paper) in which a surface layer is formed on an ink absorbing layer by spraying a coating liquid on the ink absorbing layer formed on a support. The present invention relates to a curtain spray coating method, a curtain spray coating apparatus for coating a surface layer, and a recording sheet.

  Inkjet recording is a method in which micro droplets of ink are ejected by various operating principles and deposited on recording paper to record images, characters, etc., but they are relatively high speed, low noise, and easy to multicolor. It has some advantages. In particular, since the image quality of printers has recently improved and has reached photographic image quality, the recording paper also realizes photographic image quality and reproduces the texture (glossiness, smoothness, stiffness, etc.) of silver halide photography. Is required.

  As one method for reproducing the texture of a silver salt photograph, a so-called swelling type recording paper is known in which a hydrophilic binder such as gelatin or polyvinyl alcohol is coated on a support. However, the recording paper produced by this method has drawbacks such as a slow ink absorption speed, a sticky surface after printing, and an image that tends to bleed due to humidity during storage. In particular, since the ink absorption speed is slow, ink droplets mix before being absorbed, and it is easy to cause bleeding between different colors (bleeding) and uneven color within the same color (beading). It is very difficult to obtain a degree of image quality.

  The so-called void type is becoming the mainstream instead of the above swelling type, and the ink absorption layer has porous inorganic fine particles, and the ink is absorbed by the porous inorganic fine particles, so the absorption speed is fast. Is a feature. Examples of such void-type recording paper include JP-A-10-119423, JP-A-10-119424, JP-A-10-175364, JP-A-10-193976, JP-A-10-19376, and JP-A-10-217601. 11-20300, 11-106694, 11-321079, 11-348410, 10-178126, 11-348409, JP-A-2000-27093, 2000-94830, 2000- 158807, 2000-211121, etc.

  On the other hand, in addition to image quality and texture, demands for durability and image storage stability have become higher, and many attempts have been made to reach the silver salt photography level in terms of light resistance, moisture resistance, water resistance, and the like. Examples of the improvement in light resistance include JP-A-57-74192, JP-A-57-87989, JP-A-57-74193, JP-A-58-152072, JP-A-1-95091, JP-A-1-95091 and JP-A-1-95091. 115677, 3-13376, 4-7189, 7-195824, 8-25796, 11-321090, 11-277893, JP-A-2000-37951, and the like. A number of techniques have been disclosed.

  In the case of a void type recording paper, there is not only light resistance but also a problem that it easily causes discoloration due to a trace amount of active harmful gas in the air such as ozone, oxidant, SOx, NOx due to the void structure. In particular, discoloration tends to occur with phthalocyanine-based aqueous dyes used in general color ink jet printers.

  As described above, a method of providing a surface layer on the ink absorbing layer has been studied as one of countermeasures against the problems caused by the void structure of the ink absorbing layer. Providing a surface layer is effective because it does not allow a very small amount of active harmful gas in the air, such as ozone, oxidant, SOx, and NOx, to enter the void structure, and is described in JP-A-7-237348. As shown, a technique of providing a transparent polymer film having a thickness of 0.5 to 30 μm is known.

  As a method for providing the surface layer, the coating liquid is applied on the ink absorbing layer by block coating, gravure roll coating, extrusion coating, or the like.

  1) Since it is difficult to make the coating speed 50 m / min or more, the operation rate is low.

  2) Interference unevenness is likely to occur on the coated surface, resulting in a low commercial value.

  3) The film thickness distribution is unstable and it is difficult to obtain a uniform film thickness layer, which is disadvantageous for preventing invasion of harmful gases.

  4) Since it is difficult to apply a thin film having a film thickness of 5 to 20 μm, the recording paper is colored due to the influence of the film thickness. In addition, the load in the drying process increases.

  For these reasons, the surface layer for preventing the invasion of harmful gases is applied by a curtain spray coating using a curtain spray coater as a thin and uniform coating method. For example, when a coating solution is sprayed by a spray device (curtain spray device) over a coating width in a direction crossing the substrate transport direction to form a coating solution layer (surface layer) on the substrate, the sprayed coating solution Spray coating method (curtain spray coating of the present invention) using a spray device (curtain spraying device) disposed in a housing in which a spray coater (corresponding to the curtain spray coater of the present invention) is held under reduced pressure to prevent scattering. And a spray coating apparatus (corresponding to the curtain spray coating apparatus of the present invention) are known (for example, see Patent Document 1).

  The curtain spray coating apparatus described in Patent Document 1 is effective in preventing the coating liquid sprayed over the entire coating process from scattering, but has the following problems.

  1) There is a risk that the coating liquid adhering to the wall in the casing during coating drops onto the coating film, resulting in droplet unevenness (coating unevenness), which may cause failure.

  2) From the gap between the case housing the curtain spray coating device and the support, spray-like liquid droplets of the coating liquid that have not been used for coating scatter, and the scattered liquid droplets adhere to the support again to form a liquid. There is a risk of causing droplet unevenness (coating unevenness). In addition, scattered droplets may contaminate the curtain spray coating process.

From such a situation, the coating liquid is applied on the at least one ink absorbing layer formed on the support by a curtain spray coating device, and a surface layer is formed to produce a recording paper. To develop a curtain spray coating method for the surface layer of recording paper, a curtain spray coating device for recording the surface layer, and recording paper, which can prevent coating failure due to dropping of liquid droplets and can be applied safely for a long time. Is desired.
JP 2004-90330 A

  The present invention has been made in view of the above-described situation, and an object of the present invention is to coat a coating liquid on a at least one ink absorbing layer formed on a support with a spray coating apparatus, and to form a surface layer. When forming and forming recording paper, spraying method for surface layer of recording paper, spraying for surface layer application, which can prevent application failure due to dropping of droplets during application and can be applied safely for a long time It is to provide a coating device and recording paper.

  The above object of the present invention has been achieved by the following constitution.

  (1) On the at least one ink absorbing layer formed on the support that is supported by the backup roll and continuously transported, the curtain spray coating device disposed at a position that intersects the transport direction of the support; In the curtain spray coating method for the surface layer of an ink jet recording paper, the coating liquid is curtain spray applied to the entire width in the width direction of the ink absorbing layer to form a surface layer. The curtain spray coating device includes a curtain spray coater and a scattering coating liquid. The splash coating liquid recovery device has an opening on the curtain spray coater side, a side plate having a suction port, a top plate having a gas intake port, and a bottom plate. The casing has a structure, and the inside of the casing is depressurized through the suction port during curtain spray application, and gas is supplied from the gas intake port. Incorporating scattering coating liquid was recovered while, curtain spray coating method of the surface layer and performing the coating.

  (2) The splash coating liquid recovery device has an opening abutted against a wall surface in the width direction of the curtain spray coater, and a bottom plate is disposed so as to be close to the outer peripheral surface of the backup roll, upstream of the curtain spray coater The surface layer curtain spray coating method according to (1), wherein the surface layer is disposed on the downstream side and the downstream side.

  (3) The surface layer according to (1) or (2), wherein the gas inlet is disposed at least near the tip of the top plate in parallel with the wall surface in the width direction of the curtain spray coater. Curtain spray application method.

  (4) The gas inlet is a long hole having a length of 1 to 50 mm and 90 to 120% of the width of an object to be coated provided in the width direction of the curtain spray coater. The curtain spray coating method for a surface layer according to any one of (1) to (3).

  (5) Any one of the above (1) to (3), wherein the gas inlet has square holes with a length of 1 to 500 mm and a width of 1 to 50 mm arranged at an interval of 1 to 50 mm. A method for applying a surface layer curtain spray according to claim 1.

  (6) The surface according to any one of (1) to (3), wherein the gas inlet has round holes with a diameter of 1 to 50 mm arranged at intervals of 1 to 100 mm. Curtain spray application method of layer.

  (7) The surface layer curtain spray coating method according to any one of (1) to (6) above, wherein the velocity of the gas taken in from the gas inlet is 5 to 50 m / sec.

  (8) The curtain layer spray coating method for a surface layer according to any one of (1) to (7) above, wherein the reduced pressure inside the casing at the time of the curtain spray coating is 50 to 1000 Pa. .

  (9) When the curtain spray coater moves between the application position and the standby position, the scattering coating liquid recovery device moves between the arrangement position and the standby position in accordance with the movement of the curtain spray coater. The surface layer curtain spray coating method according to any one of (1) to (8) above, wherein:

  (10) The ink absorbing layer according to any one of (1) to (9), wherein the ink absorbing layer is composed of a porous layer containing at least one inorganic fine particle and a binder. Curtain spray coating method for surface layer.

  (11) An ink jet recording paper for forming a surface layer by curtain spraying a coating liquid on the entire width in the width direction of at least one ink absorbing layer formed on a support that is supported by a backup roll and continuously conveyed. In the curtain spray coating apparatus for surface layer coating, the curtain spray coating apparatus has a curtain spray coater, a scattering coating liquid recovery apparatus, and a moving means, and the scattering coating liquid recovery apparatus is on the curtain spray coating machine side. The housing has a side plate having a suction port, a suction plate, a top plate having a gas intake port, and a bottom plate, and the interior of the housing is formed through the suction port during curtain spray application. Curtain spray coating for surface layer coating, characterized in that it can be decompressed and gas can be taken in from the gas inlet and the scattered coating liquid can be collected. Apparatus.

  (12) The splash coating solution recovery device is arranged such that the opening is brought into contact with the wall surface in the width direction of the curtain spray coater and the bottom plate is disposed so as to be close to the outer peripheral surface of the backup roll, The curtain spray coating apparatus for coating a surface layer according to (11), wherein the curtain spray coating apparatus is disposed on the downstream side.

  (13) The surface layer coating according to (11) or (12), wherein the gas intake port is disposed at least near the top end of the top plate in parallel with the wall surface in the width direction of the curtain spray coater. Curtain spray applicator.

  (14) The gas inlet is a long hole having a length of 1 to 50 mm and 90 to 120% of the width of an object to be coated provided in the width direction of the curtain spray coater. The curtain spray coating apparatus for surface layer application | coating of any one of (13)-(13).

  (15) Any of (11) to (13) above, wherein the gas inlet has square holes with a length of 1 to 500 mm and a width of 1 to 50 mm arranged at intervals of 1 to 50 mm. A curtain spray coating apparatus for coating a surface layer according to claim 1.

  (16) The surface according to any one of (11) to (13), wherein the gas inlet has round holes with a diameter of 1 to 50 mm arranged at intervals of 1 to 100 mm. Curtain spray coating device for layer coating.

  (17) Curtain spray coating for surface layer coating according to any one of (11) to (16) above, wherein the velocity of the gas introduced from the gas inlet is 5 to 50 m / sec. apparatus.

  (18) The curtain spray for surface layer application according to any one of (11) to (17) above, wherein the pressure reduction inside the casing at the time of the curtain spray application is 50 to 1000 Pa. Coating device.

  (19) When the curtain spray coater moves between the application position and the standby position, the scattering coating liquid recovery device moves between the arrangement position and the standby position in accordance with the movement of the curtain spray coater. The curtain spray coating device for coating a surface layer according to any one of (11) to (18), wherein:

  (20) The ink absorbing layer according to any one of (11) to (19), wherein the ink absorbing layer is composed of a porous layer containing at least one inorganic fine particle and a binder. Curtain spray coating device for surface layer coating.

  (21) An inkjet recording paper produced by the surface layer curtain spray coating method according to any one of (1) to (10).

  When at least one ink absorbing layer formed on the support is coated with a coating liquid by a curtain spray coating device to form a surface layer to produce a recording paper, a droplet is dropped during coating. It is possible to provide a curtain spray coating method for the surface layer of the recording paper, a curtain spray coating device for coating the surface layer, and the recording paper, which can prevent coating failure and can be applied safely for a long time. Improved production efficiency and quality.

  Embodiments of the present invention will be described with reference to FIGS. 1 to 7, but the present invention is not limited thereto.

  FIG. 1 is a schematic diagram showing an example of a coating production line in which a curtain spray coating device is arranged. In the figure, 1 indicates a coating production line. The coating production line 1 has a surface on the feeding part 2 of the support, the first coating part 3 for applying the coating liquid for forming the ink absorbing layer, the cooling part 4, the drying part 5, and the ink absorbing layer. It has the 2nd coating part 6 and the winding-up part 7 which apply | coat a coating liquid which forms a layer by curtain spray.

  Reference numeral 202 denotes an original roll of the support 201. The support 201 fed out from the feed-out unit 2 is coated with the coater 302 to form at least one ink absorbing layer on the support 201 wound around the backup roll 301 in the first coating unit 3. . The ink absorbing layer is preferably composed of a porous layer containing at least one inorganic fine particle and a binder. The coater 302 is preferably a flow-rate type slide bead coating apparatus because it can simultaneously apply a plurality of coating liquids.

  The support having the coating liquid layer for forming the ink absorbing layer on the support 201 is in a state where the coating liquid for the ink absorbing layer contains a hydrophilic binder and is fixed by the cooling device 401 in the cooling unit 4. Then, the ink is transported to the drying unit 5 where the solvent is removed and the ink absorbing layer 203 is formed. Reference numeral 501 denotes a drying box, 502 denotes a conveyance roll, and 503 denotes a reverser that reversely conveys the gas for floating and conveying the support in a non-contact manner with the surface of the coating film in order to avoid contact with the coating surface. . Thereby, it is possible to dry by avoiding contact of the coated surface.

  When the solvent in the coating liquid layer is removed by the drying unit 5 and the ink absorbing layer 203 is formed, the second coating unit 6 disposed outside the drying unit 5 is wound around the back up roll 602. The coating liquid for the surface layer is spray applied by the curtain spray coating device 601 on the ink absorbing layer 203 of the support. The support coated with the coating solution for the surface layer enters the drying box again and is dried, the solvent of the coating solution for the surface layer is removed, the surface layer 204 is formed, exits from the drying box, and is wound up. The roll-shaped recording paper 702 is manufactured by being wound around the winding core 701 by the section 7. The drying in the drying section is preferably performed by blowing hot air (the hot air blowing means is not shown). In the present invention, the surface layer formed on the ink absorbing layer includes a state where a part of the coating liquid permeates into the ink absorbing layer when the coating liquid is applied by curtain spray coating on the ink absorbing layer.

  The position where the second coating unit 6 is disposed is particularly limited as long as it can be dried again after coating in the middle of the drying process, preferably after the rate-decreasing drying, and outside the drying unit. There is no. For example, the drying unit shown in the figure may be divided into two parts, a first drying unit and a second drying unit, and arranged between the first drying unit and the second drying unit, or as shown in the figure. Although it may be arranged on the upper part of the drying box of the drying part, it is preferably arranged on the upper part of the drying box of the drying part in order to accommodate the members constituting the second coating part 6 without increasing the process. . The curtain spray coating device 601 of the second coating unit 6 is disposed so as to face the coating surface of the support that is a direction orthogonal to the transport direction. Details of the second coating unit 6 will be described with reference to FIG. The following effect is acquired by taking out the 2nd coating part 6 out of a drying part, and apply | coating a surface layer on the ink absorption layer on the support body supported by the backup roll.

  1) Because the coating liquid splashes due to curtain spray application can prevent contamination of the transport roll and the inner wall of the drying box, it prevents foreign matter from adhering due to the transfer of the foreign matter attached to the transport roll, and foreign matter from falling from the inner wall of the drying box. Product performance can be stabilized.

  2) Since the drying part is not enlarged, the loss of energy required for drying can be minimized.

  3) Maintenance of the curtain spray coating device is facilitated.

  4) Since the coating is carried out while being supported by the backup roll, there is no fluttering of the support and stable coating is possible, and the product performance is stabilized.

  FIG. 2 is a schematic enlargement of a portion indicated by X in FIG. FIG. 2A is a schematic enlarged perspective view of a portion indicated by X in FIG. FIG. 2B is a schematic enlarged cross-sectional view of a portion indicated by AA ′ in FIG.

  The curtain spray coating apparatus 601 includes a curtain spray coater (hereinafter also simply referred to as a coater) 601a, and a scattered coating liquid recovery apparatus 601b provided on the upstream side and the downstream side of the coater 601a. The scattered coating liquid recovery device 601b provided on the upstream side and the downstream side has the same structure and the same function. Reference numeral 601a1 denotes a coating liquid supply pipe that is disposed on the top surface 601a3 of the coater 601a and supplies a coating liquid to the coater 601a. 601a2 is disposed on a side surface 601a4 in the width direction of the coater 601a and is applied to the coater 601a. The gas supply pipe which supplies gas to the coater 601a in order to spray a liquid is shown. Pressurized gas is supplied from the gas supply pipe 601a2. The position where the gas supply pipe 601a2 is disposed may be the top surface 601a3, and can be selected from the structure of the top plate 601b2.

  Reference numeral 601b1 denotes a main body of the scattered coating liquid recovery apparatus 601b. The main body 601b1 has the coater 601a side as a front portion and the opposite side as a rear portion. The main body 601b1 has a structure of a top plate 601b2, a side plate 601b3 (601b4), a bottom plate 601b5, a rear side plate 601b6 at both ends, and an opening 601b7 on the coater 601a side.

  The splash coating solution collecting device 601b is disposed on the upstream side and the downstream side of the coater 601a in a state where the top in the width direction of the top plate 601b2 contacts the side surface 601a4 in the width direction of the top plate 601b2. Reference numeral 601b8 denotes a suction chamber inside the main body 601b1 having a housing structure. Reference numeral 601b9 denotes a suction pipe that is attached to the rear side plate 601b6 and that decompresses the suction chamber 601b8 inside the main body 601b1. The suction pipe 601b9 is connected to a vacuum pump (not shown) and makes it possible to reduce the pressure in the suction chamber 601b8 of the main body 601b. An adjustment valve (not shown) may be attached to the suction pipe 601b9 in order to adjust the suction amount of the suction chamber 601b8.

  The number of suction pipes 601b9 to be attached varies depending on the size of the coater 601a, the amount of coating liquid supplied to the coater 601a, and the like, and can be changed as appropriate. This figure shows the case of one. Liquid droplets 901 (see FIG. 6) that are floating without being involved in the application with the application liquid sprayed from the coater 601a by sucking the inside of the suction chamber 601b8 through the suction pipe 601b9 (spray state) This coating liquid can be eliminated without scattering. 601b10 is a coating liquid sprayed by the coater 601a in the suction chamber 601b8, and is not removed by the suction pipe 601b9, but is collected on the inner wall of the suction chamber 601b8 and collects the collected coating liquid that has accumulated. Indicates.

  Reference numeral 601b11 denotes a gas intake port disposed on the coater 601a side of the top plate 601b2. The gas inlet 601b11 is preferably disposed in the vicinity of the top end of the top plate 601b2 that contacts the side surface in the width direction of the coater 601a and in the width direction of the top plate 601b2. By introducing the gas from the gas intake port 601b11 at the time of suction, the gas flow in the suction chamber 601b8 flows toward the suction pipe 601b9. For this reason, the coating liquid sprayed from the coater 601a in a liquid droplet 901 (see FIG. 6) state (see FIG. 6) that is floating without being involved in the coating is scattered in the suction chamber 601b8. Suppressed and easily removed via the suction tube 601b9.

  The method for disposing the gas inlet 601b11 on the top plate 601b2 is not particularly limited. For example, a hole may be directly formed in the top plate 601b2, a notch may be formed at the tip, The cylindrical shape which raised the side wall may be sufficient. This figure has shown the case where it is set as the cylindrical shape.

  The gas velocity taken into the suction chamber 601b8 from the gas inlet 601b11 at the time of curtain spray application is preferably 5 to 50 m / sec in consideration of disturbance of the air flow in the casing, disturbance of the spray state, and the like.

  The reduced pressure inside the housing at the time of curtain spray application is preferably 50 to 1000 Pa in consideration of disordered spray state, coating rate, and the like. 50 to 300 Pa is particularly preferable.

  FIG. 3 is a schematic plan view of the curtain spray coating apparatus shown in FIG.

  In the figure, G indicates the length of the gas inlet 601b11. The length G is preferably 1 to 50 mm. H indicates the width of the gas inlet 601b11. The width H is preferably 90 to 120% of the width of the object to be coated in consideration of uniform air supply into the casing.

  θ1 represents an angle at which the coater 601a and the support 201 intersect. In the present invention, “crossing” means an angle at which a line forming the spray port P (see FIG. 6) of the coater 601a is parallel to the support and crosses the traveling direction of the support. That is, it means that the coater 601a is disposed at a position that intersects the conveying direction of the support (the arrow direction in the figure). The angle θ1 is preferably 70 to 110 ° in consideration of the application range of the application liquid, the setting of the spray condition of the application liquid, and the like. In the case of this figure, the case where the angle at which the coater 601a and the support intersect is 90 °.

  The belt-like support 201 is moved (conveyed) relative to the coating liquid discharge portion of the coater 601a to perform continuous coating. The spray port P (see FIG. 5) of the coating liquid of the coater 601a is at least the coating width of the strip-shaped support 201 (the length of the coated portion of the strip-shaped support in the direction crossing the transport direction of the strip-shaped support) And is disposed so as to intersect the transport direction of the belt-like support 201. By arranging in this way, the belt-like support is conveyed to the coater 601a, and the coating liquid is sprayed on the belt-like support as droplets over the coating width, thereby reducing the drying load and the film thickness. It is possible to apply a thin coating film with high uniformity. Other symbols are the same as those in FIG.

  FIG. 4 is a schematic plan view of the curtain spray coating apparatus shown in FIG. 3 in which a scattering coating liquid recovery apparatus having a different shape and position of the gas inlet is provided. FIG. 4A shows a curtain spray in which a spray coating liquid recovery device having a gas inlet provided in a cutout shape at the tip of the top plate of the spray coating liquid recovery device that contacts the side surface in the width direction of the coater. It is a schematic plan view of a coating device. In FIG. 4B, a spray coating liquid recovery device having a gas inlet provided in the vicinity of the top of the top of the spray coating liquid recovery device that contacts the side surface in the width direction of the coater is disposed. It is a schematic plan view of a curtain spray coating apparatus.

  A description will be given of the scattered coating liquid recovery apparatus shown in FIG. In the figure, reference numeral 601b12 denotes a notch-shaped gas inlet provided at the tip of the top plate 601b2 of the splash coating solution recovery apparatus 601b that contacts the side surface in the width direction of the coater 601a.

  G ′ indicates the length of the gas inlet 601b12. The length G ′ is preferably 1 to 50 mm. H ′ indicates the width of the gas inlet 601b12. The width H ′ is preferably 90 to 120% of the width of the object to be coated in consideration of uniform air supply into the casing.

  A description will be given of the scattering coating liquid recovery apparatus shown in FIG. In the figure, reference numeral 601b13 denotes a hole-like gas inlet provided at the tip of the top plate 601b2 of the scattering coating liquid recovery apparatus 601b that contacts the side surface in the width direction of the coater 601a.

  G ″ represents the length of the gas inlet 601b13. The length G ″ is preferably 1 to 50 mm. H ″ indicates the width of the gas inlet 601b13. The width H ″ is preferably 90 to 120% of the width of the object to be coated in consideration of uniform supply of air into the casing.

  I indicates the distance from the tip of the top plate 601b2 to the edge of the hole-like gas inlet 601b13 on the coater 601a side. The distance I is preferably 0 to 50 mm in consideration of uniform air supply into the housing. In the present invention, the vicinity indicates the above range.

  FIG. 5 is a partially enlarged schematic plan view of a gas inlet having another shape. FIG. 5A is a partially enlarged schematic plan view of a gas intake port in which a plurality of square holes are arranged at equal intervals. FIG. 5B is a partially enlarged schematic plan view of a gas intake port in which a plurality of round holes are arranged in a staggered manner.

  A description will be given with reference to the gas inlet shown in FIG. In the figure, reference numeral 8a denotes a gas inlet and has a plurality of square holes 8a1. J indicates the width of the square hole 8a1. The width J is preferably 1 to 500 mm in consideration of the blower capacity, the degree of pressure reduction, and the like. K indicates the width of each square hole 8a1. The width K is preferably 1 to 50 mm in consideration of uniform air supply into the housing.

  A description will be given with reference to the gas inlet shown in FIG. In the figure, 8b indicates a gas inlet. 8b1 represents a round hole. J indicates the width of the square hole 8a1. The width J is preferably 1 to 50 mm. M shows the space | interval between each round hole 8b1. The distance M is preferably 1 to 100 mm in consideration of uniform air supply into the housing.

  FIG. 6 is a schematic diagram showing the state of droplets in the suction chamber of the scattered coating liquid recovery apparatus when spray coating is performed. FIG. 6A is a schematic diagram showing the state of droplets in the suction chamber of the scattered coating liquid recovery apparatus that does not have a gas inlet. FIG. 6B is a schematic diagram showing the state of droplets in the suction chamber of the scattered coating liquid recovery apparatus with a gas inlet.

  In the figure, reference numeral 601b 'denotes a scattering coating liquid recovery device having no gas inlet, and 601b'8 denotes a suction chamber. Reference numerals 601a5 to 601a8 denote blocks constituting the coater 601a. Reference numeral 601a9 denotes a pressurized gas pocket including a block 601a5 and a block 601a6, and reference numeral 601a10 denotes a gas nozzle formed in a gap between the block 601a5 and the block 601a6. Reference numeral 601a11 denotes a gas pocket composed of a block 601a7 and a block 601a8, and reference numeral 601a12 denotes a gas nozzle composed of the block 601a7 and the block 601a8.

  The gas supplied from the pressurized gas supply source (not shown) through the gas supply pipes 601a2 is temporarily stored in the gas pockets 601a9 and 601a11, and then opened through the gas nozzles 601a10 and 601a12. It is ejected from the ends 601a13 and 601a14.

  Reference numeral 601a15 denotes a coating liquid pocket that is composed of a block 601a6 and a block 601a7 and temporarily stores the coating liquid supplied from the coating liquid supply pipe 601a1. Reference numeral 601a16 denotes a coating liquid nozzle formed by the block 601a6 and the block 601a7. The coating liquid stored in the coating liquid pocket 601a16 is discharged from the opening end 601a17 of the coating liquid nozzle 601a15, and at the same time, the pressurized gas ejected from the opening end 601a13 of the gas nozzle 601a10 and the opening end 601a14 of the gas nozzle 601a12. The spray is sprayed and applied onto the ink absorbing layer 203 on the belt-like support 201. Further, the distance between the spray port P of the coater 601a (consisting of the opening end 601a13, the opening end 601a14, and the opening end 601a17) and the ink absorbing layer can be appropriately selected within a range of approximately 2 to 50 mm. Reference numeral 9 denotes a droplet sprayed from the spray port P, and reference numeral 901 denotes a droplet that floats without being involved in application.

  The state of the droplets in the suction chamber shown in FIG. Since the suction chamber 601b'8 does not have a gas intake port, among the droplets sprayed from the spray port P, the droplets not involved in the coating soar with the momentum of the pressurized gas ejected from the spray port P (arrow in the figure). Direction) It spreads over the entire suction chamber 601b'8. On the other hand, the suction chamber 601b'8 is sucked through the suction pipe 601b'9. For this reason, the droplet 901 spreading over the entire suction chamber 601b'8 is sequentially removed from the suction chamber 601b'8 via the suction tube 601b'9.

  By disposing the scattered coating liquid recovery device 601b ′ having the suction chamber 601b′8 having no gas intake port, the liquid droplets 901 which are not involved in the application are confined in the suction chamber 601b′8. Although it became possible to prevent the surrounding pollution by scattering, the following problems were raised.

  In the case of applying for a long time, a part of the droplet 901 spreading over the entire suction chamber 601b'8 is formed on the inner wall of the suction chamber 601b'8 and the side surface 601a4 in the width direction of the coater 601a in the suction chamber 601b'8. There is a risk that it adheres, condenses, becomes a cocoon-like shape, falls onto the ink absorption layer, and causes droplet unevenness. For this reason, it becomes difficult to apply for a long time, which is one of the reasons why the production efficiency is not increased because the application is stopped halfway and the inside of the suction chamber 601b'8 is cleaned and then applied again.

  The state of the liquid droplet in the suction chamber shown in FIG. 6B will be described. The suction chamber 601b8 is disposed in the vicinity of the tip of the top plate 601b2 where the gas inlet 601b11 contacts the side surface in the width direction of the coater 601a. The suction chamber 601b8 is sucked through the suction pipe 601b9 to be decompressed. For this reason, outside air is taken into the suction chamber 601b8 from the gas inlet 601b11 (in the direction of the arrow in the figure). Due to the outside air taken in, of the droplets sprayed from the spray port P, scattering of the droplets 901 that are not involved in the application in the suction chamber 601b8 is suppressed, and it is prevented that the droplets 901 spread over the entire suction chamber 601b8. In addition, the flow of outside air taken into the suction chamber 601b8 is formed toward the suction port 601b14, and the droplets 901 that are not involved in the application are efficiently removed outside through the suction tube 601b9. For this reason, the droplets 901 adhering to the inner wall of the suction chamber 601b8 and the side surface 601a4 in the width direction of the coater 601a in the suction chamber 601b8 are drastically reduced. The risk of falling into the water can be greatly reduced, long-time application is possible, and production efficiency can be increased.

In the coater shown in this figure, the angle of the gas nozzle relative to the cloth liquid nozzle is preferably in the range of 5 to 50 deg. The supply amount of the coating solution from the coating solution nozzle cannot be defined unconditionally depending on the desired coating thickness, coating solution concentration, coating speed, etc., but is generally 1 to 50 g / m as the coating amount on the substrate. A range of ² is preferred. If it is less than 1 g / m ² , it may be difficult to form a stable and uniform coating film. Conversely, if it exceeds 50 g / m ² , it is necessary to increase the drying load, lengthen the drying process, or increase the temperature. May occur and useless costs may be incurred. The wet film thickness of the coating solution is 1 to 50 μm, and preferably 5 to 30 μm.

  On the other hand, the gas ejected from the gas nozzle is not particularly limited as long as it is suitable for coating. Generally, air is used, but the gas supply condition is generally 1 to 50 CMM / m (flow rate per coating width). The internal pressure at the gas nozzle at that time is preferably 10 kPa or more from the viewpoint of coating uniformity.

  The gas linear velocity v is preferably 126 to 400 m / s from the viewpoint of coating drying property and coating yield. The gas linear velocity is a gas linear velocity immediately after the exit of the gas nozzle, and can be determined by measuring with a laser Doppler anemometer, for example, 1D FLV system 8851 manufactured by KANOMAX. The coating yield is the amount of coating solution applied on the ink absorbing layer / the total amount of coating solution supplied × 100 (%), and is calculated by the mass method. That is, the amount of coating liquid applied on the ink absorption layer is calculated from the change in mass before and after application on the ink absorption layer, and the total amount of coating liquid supplied is supplied to the curtain spray coater, that is, the supplied mass, It can be determined from the liquid feed flow rate x the coating time.

  FIG. 7 is a schematic diagram showing a moving state of the coater and the scattered coating liquid recovery device at the start of coating of the spray coating device shown in FIG. The reference numerals in the figure are the same as those in FIG.

  The coater 601a moves from the standby position (the position of the coater 601a indicated by the dotted line) to the application position (the position of the coater 601a indicated by the solid line) at the start of application (in the direction of the arrow in the drawing), and waits from the application position after the application is completed. It is arranged on a frame (not shown) of the spray coating device so that it can be moved by a moving means (not shown). Further, the backup roll 602 is also pivotally supported on a frame (not shown) so as to be rotatable in the same direction as the conveying direction of the support 201 (the arrow direction in the figure).

  The main body 601b1 of the coating liquid splash preventing means 601b moves from the standby position (position of the main body 601b1 of the coating liquid splash preventing means 601b indicated by the dotted line) to the arrangement position (position contacting the coater 601a indicated by the solid line) at the start of coating. (In the direction of the arrow in the figure), and after the application is completed, it is arranged on the frame (not shown) of the curtain spray application device so that it can be moved from the arrangement position to the standby position by the moving means (not shown).

  As shown in this figure, by making the coater 601a and the coating liquid splash prevention means 601b stand by at the standby position before coating, maintenance and adjustment at the standby position are facilitated, and stable coating can be performed immediately after the start of coating. This is preferable because it becomes possible.

  As the coating solution for forming the surface layer according to the present invention, it is preferable to use coating solutions described in JP-A Nos. 2004-906 and 2004-122705.

  The ink absorbing layer in the present invention will be described. That the ink absorbing layer is porous means having a large number of voids having a pore diameter of about 5 to 200 nm. It is preferable that the gaps are not isolated independently but are continuously connected to each other. As a definition of the void diameter in this case, for example, a measured value by a mercury intrusion method can be used. Hereinafter, a preferable porous layer will be described.

  The porous layer is mainly formed by soft aggregation of a hydrophilic binder and inorganic fine particles. Conventionally, various methods for forming voids in a film are known. For example, a uniform coating solution containing two or more kinds of polymers is coated on a support, and these polymers are phase-separated from each other in the drying process. A method of forming voids by applying a coating liquid containing solid fine particles and a hydrophilic or hydrophobic resin on a support, and after drying, the inkjet recording paper is immersed in water or a liquid containing an appropriate organic solvent. , A method of creating voids by dissolving solid fine particles, a method of forming voids in a film by applying a coating liquid containing a compound having a property of foaming during film formation, and then foaming this compound in the drying process, porous A coating solution containing a porous solid fine particle and a hydrophilic binder on a support to form voids in the porous fine particles or between the fine particles, and having a volume approximately equal to or larger than the hydrophilic binder The solid particulates and or coating solution containing a particulate oil and a hydrophilic binder is coated on a support, and a method of forming an air gap between the solid particles are known. In the present invention, it is particularly preferable that the porous layer is formed by containing various inorganic solid fine particles having an average droplet diameter of 100 nm or less.

  Examples of the inorganic fine particles used for the above purpose include light calcium carbonate, heavy calcium carbonate, magnesium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide. , Zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide, lithopone, zeolite, magnesium hydroxide, etc. A white inorganic pigment etc. can be mentioned.

  The average droplet diameter of the inorganic fine particles is determined by observing the particles themselves or the particles appearing on the cross section or surface of the porous layer with an electron microscope, measuring the particle size of 1,000 arbitrary particles, and calculating a simple average value ( (Number average). Here, the particle size of each particle is represented by the diameter when a circle equal to the projected area is assumed. As the inorganic fine particles, it is preferable to use solid fine particles selected from silica and alumina or alumina hydrate.

  As silica that can be used in the present invention, silica synthesized by an ordinary wet method, colloidal silica, silica synthesized by a gas phase method, or the like is preferably used. Colloidal silica or fine particle silica synthesized by a vapor phase method is preferred, and among these, fine particle silica synthesized by a vapor phase method is preferred because a high porosity can be obtained. Alumina or alumina hydrate may be crystalline or amorphous, and any shape such as amorphous particles, spherical particles, and acicular particles can be used.

  The inorganic fine particles preferably have a particle size of 100 nm or less. For example, in the case of the gas phase method fine particle silica, the average droplet diameter of the primary particles of the inorganic fine particles dispersed in the primary particle state (particle size in the dispersion state before coating) is preferably 100 nm or less. More preferably, it is 4-50 nm, Most preferably, it is 4-20 nm.

  For example, Aerosil manufactured by Nippon Aerosil Co., Ltd. is commercially available as the silica synthesized by the vapor phase method in which the average droplet diameter of primary particles is 4 to 20 nm. The vapor phase fine particle silica can be dispersed to primary particles relatively easily by being sucked and dispersed in water using, for example, a jet stream inductor mixer manufactured by Mitamura Riken Kogyo Co., Ltd.

  In the present invention, a water-soluble binder can be used for the ink absorbing layer. Examples of the water-soluble binder that can be used in the present invention include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinyl pyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, color ginnan (κ, ι, λ, etc.), agar , Pullulan, water-soluble polyvinyl butyral, hydroxyethyl cellulose, carboxymethyl cellulose and the like. These water-soluble binders can be used in combination of two or more.

  The water-soluble binder preferably used in the present invention is polyvinyl alcohol.

  The polyvinyl alcohol preferably used in the present invention includes, in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, modified polyvinyl alcohol such as polyvinyl alcohol having a cation-modified terminal and anion-modified polyvinyl alcohol having an anionic group. Alcohol is also included.

  The polyvinyl alcohol obtained by hydrolyzing vinyl acetate preferably has an average degree of polymerization of 1,000 or more, and particularly preferably has an average degree of polymerization of 1,500 to 5,000. The degree of saponification is preferably 70 to 100%, particularly preferably 80 to 99.5%.

  Examples of the cation-modified polyvinyl alcohol have primary to tertiary amino groups or quaternary ammonium groups in the main chain or side chain of the polyvinyl alcohol, as described in JP-A-61-110483. Polyvinyl alcohol, which is obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate.

  Examples of the ethylenically unsaturated monomer having a cationic group include trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl) ammonium chloride. N-vinylimidazole, N-vinyl-2-methylimidazole, N- (3-dimethylaminopropyl) methacrylamide, hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1, 1-dimethyl-3-dimethylaminopropyl) acrylamide and the like.

  The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, relative to vinyl acetate.

  Anion-modified polyvinyl alcohol is, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-2060888, as described in JP-A-61-237681 and JP-A-63-330779, Examples thereof include a copolymer of vinyl alcohol and a vinyl compound having a water-soluble group, and modified polyvinyl alcohol having a water-soluble group as described in JP-A-7-285265.

  Nonionic modified polyvinyl alcohol is, for example, a polyvinyl alcohol derivative obtained by adding a polyalkylene oxide group to a part of vinyl alcohol as described in JP-A No. 7-9758, and described in JP-A No. 8-25795. And a block copolymer of a vinyl compound having a hydrophobic group and vinyl alcohol. Polyvinyl alcohol can be used in combination of two or more, such as the degree of polymerization and the type of modification.

  In the present invention, it is preferable to use a polyvalent metal compound as a dye-fixing agent, and it does not preclude the combined use of a cationic polymer together with these compounds within the scope of achieving the object effect of the present invention.

Examples of cationic polymers include polyethyleneimine, polyallylamine, polyvinylamine, dicyandiamide polyalkylene polyamine condensate, polyalkylene polyamine dicyandiamide ammonium salt condensate, dicyandiamide formalin condensate, epichlorohydrin-dialkylamine addition polymer, diallyldimethylammonium chloride polymers, diallyl dimethyl ammonium chloride-SO ₂ copolymer, polyvinyl imidazole, polyvinyl pyrrolidone, vinyl imidazole copolymers, polyvinyl pyridine, polyamidine, chitosan, cationized starch, vinylbenzyltrimethylammonium chloride polymers, (2-methacryloyl Oxyethyl) trimethylammonium chloride polymer, dimethylaminoethyl meta Relate polymer and the like.

  Moreover, the cationic dye described in the Chemical Industry Times, August 15 and 25, 1998, and the polymer dye fixing agent described in “Introduction to Polymer Drugs” issued by Sanyo Chemical Industries, Ltd. are examples.

The amount of inorganic fine particles used in the ink absorption layer depends largely on the required ink absorption capacity, the porosity of the porous layer, the type of inorganic pigment, and the type of water-soluble binder, but generally 1 m ^{2 of} recording paper. Usually, it is 5-30 g, preferably 10-25 g. The ratio of the inorganic fine particles and the water-soluble binder used in the ink absorption layer is usually 2: 1 to 20: 1 by mass ratio, and particularly preferably 3: 1 to 10: 1. Further, it may contain a cationic water-soluble polymer having a quaternary ammonium base in the molecule, and is usually used in the range of 0.1 to 10 g, preferably 0.2 to 5 g per 1 m ^{2 of} the ink jet recording paper. .

In the porous layer, the total amount of voids (void volume) is preferably 20 ml or more per 1 m ² of recording paper. When the void volume is less than 20 ml / m ² , the ink absorbency is good when the amount of ink at the time of printing is small, but when the amount of ink increases, the ink is not completely absorbed and the image quality deteriorates, Problems such as delay in drying are likely to occur.

  In the porous layer having ink holding ability, the void volume with respect to the solid content volume is referred to as the porosity. In the present invention, it is preferable to set the porosity to 50% or more because the voids can be efficiently formed without unnecessarily increasing the film thickness.

  As another type of void type, in addition to forming an ink absorbing layer using inorganic fine particles, a polyurethane resin emulsion, a water-soluble epoxy compound and / or an acetoacetylated polyvinyl alcohol, and an epichlorohydrin polyamide resin are used in combination. The ink absorbing layer may be formed using the applied coating liquid. The polyurethane resin emulsion in this case is preferably a polyurethane resin emulsion having a polycarbonate chain, a polycarbonate chain and a polyester chain and a particle diameter of 3.0 μm, and the polyurethane resin of the polyurethane resin emulsion is a polyol having a polycarbonate polyol, a polycarbonate polyol and a polyester polyol. Further, the polyurethane resin obtained by reacting the aliphatic isocyanate compound with sulfonic acid group in the molecule further has epichlorohydrin polyamide resin and water-soluble epoxy compound and / or acetoacetylated vinyl alcohol. preferable. The ink absorbing layer using the polyurethane resin is presumed that a weak aggregation of cations and anions is formed, and accordingly, voids having an ink solvent absorbing ability are formed, so that an image can be formed.

  In the present invention, it is preferable to use a curing agent. The curing agent can be added at any time during the production of the ink jet recording paper. For example, the curing agent may be added to the coating liquid for forming the ink absorbing layer.

  In the present invention, a method of supplying a water-soluble binder curing agent after forming the ink absorbing layer may be used alone, but preferably, the above-described curing agent is added to the coating liquid for forming the ink absorbing layer. It is to be used in combination with the method.

  The curing agent that can be used in the present invention is not particularly limited as long as it causes a curing reaction with a water-soluble binder, but boric acid and its salts are preferable, but other known ones can be used. Specifically, it is a compound having a group capable of reacting with a water-soluble binder or a compound that promotes the reaction between different groups of the water-soluble binder, and is appropriately selected according to the type of the water-soluble binder. Specific examples of the curing agent include, for example, epoxy curing agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl- 4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde curing agents (formaldehyde, glioxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy-1,3,5) -S-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum and the like.

  Boric acid or a salt thereof refers to an oxygen acid having a boron atom as a central atom and a salt thereof, specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, and octaboron. Examples include acids and their salts.

  Boric acid having a boron atom as a curing agent and a salt thereof may be used as a single aqueous solution or as a mixture of two or more. Particularly preferred is a mixed aqueous solution of boric acid and borax.

  The aqueous solutions of boric acid and borax can be added only in relatively dilute aqueous solutions, respectively, but by mixing both, a concentrated aqueous solution can be obtained and the coating solution can be concentrated. Further, there is an advantage that the pH of the aqueous solution to be added can be controlled relatively freely. The total amount of the curing agent used is preferably 1 to 600 mg per 1 g of the water-soluble binder.

  Various additives other than those described above can be used for the ink absorbing layer of the recording paper according to the present invention and other layers provided as necessary. For example, organic latex fine particles such as polystyrene, polyacrylic acid esters, polymethacrylic acid esters, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or a copolymer thereof, urea resin, or melamine resin , Anionic, cationic, nonionic, betaine type surfactants, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192 No. 57-87989, No. 60-72785, No. 61-146591, No. 1-95091 and No. 3-13376, etc., No. 59-42993, 59-52689, 62-280069, 61-242871 and JP-A-4 209266, etc., optical brighteners, sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and other pH adjusters, antifoaming agents, preservatives, thickeners, antistatic agents Various known additives such as an agent and a matting agent can also be contained.

The ink absorbing layer may be composed of two or more layers. In this case, the structures of the ink absorbing layers may be the same or different from each other. The porous layer as described above is particularly preferably used in the ink jet recording method. The void volume of the porous layer preferable for the ink jet recording method is 10 to 30 ml / m ² .

  The coating layer in the recording paper of the present invention can be applied by a conventionally known coating method, for example, gravure coating method, roll coating method, rod bar coating method, air knife coating method, spray coating method, extrusion coating method. A slide bead coating method, a curtain coating method, a slot nozzle spray coating method, or an extrusion coating method using a hopper described in US Pat. No. 2,681,294 is preferably used.

  Various additives can be used for each layer of the recording paper of the present invention. For example, organic latex fine particles such as polystyrene, polyacrylic acid esters, polymethacrylic acid esters, polyacrylamides, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, or a copolymer thereof, urea resin, or melamine resin , Anionic, cationic, nonionic, betaine type surfactants, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, JP-A-57-74192 No. 57-87989, No. 60-72785, No. 61-146591, No. 1-95091 and No. 3-13376, etc., No. 59-42993, 59-52689, 62-280069, 61-242871 and JP-A-4 209266, etc., optical brighteners, sulfuric acid, phosphoric acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and other pH adjusters, antifoaming agents, preservatives, thickeners, antistatic agents Various known additives such as an agent and a matting agent can also be contained.

  As the support that can be used in the present invention, those conventionally known for inkjet recording paper can be used as appropriate, and may be a water-absorbing support, but is preferably a non-water-absorbing support. That is, in the case of the non-water-absorbing support, a larger amount of the water-soluble organic solvent in the pigment ink remains in the recording paper than in the case of the water-absorbing support, and acts more effectively on the dissolution of organic fine particles. Therefore, it is estimated that the effect of the present invention can be remarkably exhibited. To be precise, it is preferable to use “a support that does not absorb the water-soluble organic solvent in the ink”, but here, even if a non-water-absorbing support is used, the effect of the present invention is remarkably exhibited. I think we can do it.

  Examples of the water-absorbing support that can be used in the present invention include sheets and plates having general paper, cloth, wood, and the like. In particular, paper is excellent in water absorption of the substrate itself and It is most preferable because of its excellent cost. As the paper support, the main raw materials are chemical pulps such as LBKP and NBKP, mechanical pulps such as GP, CGP, RMP, TMP, CTMP, CMP, and PGW, and wood pulp such as waste paper pulp such as DIP. It is. Further, various fibrous materials such as synthetic pulp, synthetic fibers, inorganic fibers and the like can be appropriately used as raw materials as necessary.

  If necessary, various conventionally known additives such as sizing agents, pigments, paper strength enhancers, fixing agents, fluorescent whitening agents, wet paper strength agents, cationizing agents and the like are added to the paper support. I can do it. The paper support can be produced with various paper machines such as a long net paper machine, a circular net paper machine, and a twin wire paper machine by mixing the above-mentioned fibrous material such as wood pulp and various additives. If necessary, the paper can be subjected to size press treatment with starch, polyvinyl alcohol or the like, various coating treatments, or calendar treatment on the paper making stage or paper machine.

  Non-water-absorbing supports that can be preferably used in the present invention include transparent supports and opaque supports. Examples of the transparent support include films having materials such as polyester resins, diacetate resins, triatesate resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, polyimide resins, cellophane, and celluloid. Among them, those having a property of withstanding radiant heat when used for overhead projectors (OHP) are preferable, and polyethylene terephthalate is particularly preferable. The thickness of such a transparent support is preferably 50 to 200 μm.

  Further, as the opaque support, for example, a resin-coated paper (so-called RC paper) having a polyolefin resin coating layer in which a white pigment is added to at least one of the base paper, a white pigment such as barium sulfate is added to polyethylene terephthalate. A so-called white pet is preferable.

  For the purpose of increasing the adhesive strength between the various supports and the ink absorbing layer, the support is preferably subjected to corona discharge treatment, subbing treatment or the like prior to application of the ink absorbing layer. Further, the recording paper according to the present invention is not necessarily colorless, and may be a colored recording sheet.

  In the recording paper of the present invention, it is possible to use a paper support obtained by laminating both sides of a base paper support described in JP-A-2004-122705 with polyethylene. This is particularly preferable because an image can be obtained.

  Examples of the ink absorption layer coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or an extrusion using a hopper described in US Pat. No. 2,681,294. A coating method is preferably used. The ink absorbing layer is preferably composed of a porous layer described in JP-A-2004-122705.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited to these examples. In Examples, “%” indicates mass% unless otherwise specified.

Example 1
Recording paper was produced using the coating production line shown in FIG.

<Preparation of a belt-like support coated with a porous ink absorbing layer>
(Preparation of dispersion)
To 100 g of a 15% aqueous solution of the cationic polymer (P1), 500 g of a 25% aqueous dispersion of fine particle silica (manufactured by Tokuyama, QS-20) having an average primary particle size of 12 μm, then 3.0 g of boric acid, 0 g of borax 0.7 g was added and dispersed with a high-speed homogenizer to obtain a clear blue-white dispersion.

(Preparation of coating solution)
The prepared dispersion was heated to 45 ° C., and a 10% aqueous solution of polyvinyl alcohol (manufactured by Kuraray, PVA203) and a 6% aqueous solution of polyvinyl alcohol (manufactured by Kuraray, PVA245) were each heated to 45 ° C. and then added. Subsequently, 45 degreeC pure water was added and the liquid quantity was adjusted, and the translucent coating liquid was obtained.

(Application)
On a paper support (width 1500 mm, thickness 230 μm) coated on both sides with polyethylene, the above coating solution is applied with a coating width of 1470 mm using a slide bead coating machine, and dried to form a belt-like shape coated with a porous ink absorbing layer. The support was made 10,000 m. The coating speed was 200 m / min. The amount of each component in the lower layer of the belt-like support coated with the porous ink absorbing layer is as follows, and the dry film thickness is 35 μm.

Fine silica 15g / m ²
Cationic polymer (P1) 2.2 g / m ²
Polyvinyl alcohol 2.3 g / m ²
After coating the ink absorbing layer coating liquid, the film surface temperature is lowered to 10 ° C. or lower by passing through a cooling zone maintained at 10 ° C. for 15 seconds, and then the air at the following temperature is sequentially applied to the surface of the ink absorbing layer. While being sprayed, each zone of the drying process was passed through and dried.

  Note that the total drying process in the first drying section was 360 seconds, of which the average relative humidity of the blowing air was 30% or less for the first 270 seconds. After 270 seconds, the humidity was adjusted to a relative humidity of 40 to 60%.

(Preparation of coater)
As the coater, a coater shown in FIG. 5 was prepared in which the angle of the air nozzle relative to the coating liquid nozzle was 40 deg, the coating width 1470 mm, the coating liquid nozzle gap width 60 μm, and the air nozzle gap width 200 μm.

(Preparation of splash coating solution recovery device)
A scattering coating solution recovery apparatus shown in FIG. 1-a. In addition, the length of the gas intake port of the scattering coating liquid recovery apparatus was 30 mm. The width was 100% with respect to the width of the object to be coated. For comparison, the same spray coating solution recovery device was prepared except that no gas inlet was provided. 1-b.

[Preparation of curtain spray applicator]
The prepared splash coating solution recovery device No. 1-a is disposed on the upstream side and the downstream side of the prepared coater, and the curtain spray coating apparatus No. 1 shown in FIG. 1-1 was prepared.

  For comparison, the same coater was used, and the scattered coating liquid recovery device No. 1-b, and the curtain spray coating apparatus No. 1 shown in FIG. 1-2 was prepared.

[Application of surface layer]
When the reduced-rate drying of the dry ink absorbing layer in the first drying section shown in FIG. 1-1, 1-2, and as shown in FIG. 3, the line forming the spray port of the coater is parallel to the support and is at an angle of 90 ° intersecting the direction of travel of the support. The surface layer coating liquid shown below is spray-coated to a wet film thickness of 15 μm and dried in the second drying section to produce a recording material having a surface layer. 101. The conditions of the scattering coating solution recovery apparatus were set such that the pressure inside the casing of the scattering coating solution recovery apparatus was 200 Pa, and the speed of the gas taken in from the gas inlet was 15 m / sec. The total drying process in the second drying section was 100 seconds, and a wind having a relative humidity of 40 to 60% was blown. The coating solution was filtered using a filter having a caliber of 1/20 with respect to a width of 60 μm between the coating solution nozzles. The air used was filtered using a filter having a 1/50 aperture for the air nozzle gap width of 200 μm.

  As conditions for supplying the air ejected from the air nozzle, the wind flow was 7 CMM / m, and the internal pressure at the air nozzle at that time was 8 kPa. The linear velocity v of air was 150 m / s. The gap between the spray port of the curtain spray coater and the ink absorbing layer was 20 mm, and the coating speed was 200 m / min. In addition, a scattering coating liquid recovery device was prepared and In place of 1-a, the comparative scattering coating liquid recovery device No. The coating solution for the surface layer was spray-coated so as to have a wet film thickness of 15 μm under the same conditions except that 1-b was used, and dried in the second drying section to produce a recording material having the surface layer. Comparative sample No. 102.

<Preparation of coating solution for surface layer>
A coating solution having the following composition was prepared.

160 ml of polyaluminum chloride
(Taki Chemical Co., Ltd. PAC250A, solid content 23.5%)
Water-soluble dye (D1) 2ml
840 ml of water
The viscosity was 25 mC and 0.9 mPa as a result of measurement with a B-type viscometer. The surface tension was adjusted with a surfactant so as to be 40 mN / m. For the static surface tension (SST), a surface tension meter (manufactured by Kyowa Interface Science: CBVP-Z) was used, and the surface tension value was measured by a platinum plate method when the coating solution temperature was 25 ° C.

(Evaluation)
Each prepared sample No. Table 1 shows the results of evaluations according to the evaluation method and the evaluation rank shown below, which are determined according to the droplet non-uniformity accompanying the drop of the droplets 101 and 102.

Evaluation Method for Droplet Unevenness (Granularity) With respect to the presence or absence of droplet unevenness, 10 points of a total length of 1000 m were sampled at 100 m intervals and observed visually.

Evaluation rank of coating failure ○: Uneven droplets are not visible △: Slightly visible but practically no problem level (no practically problematic level is the same condition except for water-soluble dyes when preparing samples) When a sample is prepared and a solid image is printed, it is invisible.)
×: Uneven droplets are clearly visible

  The effectiveness of the present invention was confirmed.

Example 2
<Preparation of a belt-like support coated with a porous ink absorbing layer>
Sample No. 1 prepared in Example 1 was used. A belt-like support coated with the same porous ink absorbing layer as 101 was prepared.

(Preparation of coater)
Sample No. 1 of Example 1 The same coater as that used to prepare 101 was prepared.

(Preparation of splash coating solution recovery device)
As shown in Table 2, the scattering coating liquid recovery device shown in FIG. 2-a to 2-n. The arrangement position of the gas inlet indicates the distance from the tip of the top plate of the housing on the coater side.

[Preparation of curtain spray applicator]
The same coater is used, and the scattered coating liquid recovery device No. 2-a to 2-n are arranged, and a curtain spray coating apparatus shown in FIG. 2-1 to 2-14.

[Application of surface layer]
When the reduced-rate drying of the dry ink absorbing layer in the first drying section shown in FIG. Samples Nos. 2-1 to 2-14 in Example 1 were used. A surface layer coating solution was applied under the same conditions as in 101 and dried in the second drying section to produce a recording material having a surface layer. 201-214.

(Evaluation)
Each prepared sample No. Table 3 shows the results of evaluations according to the same evaluation rank as in Example 1, in which the determination is performed in accordance with the same evaluation rank as that in Example 1, and the determination is performed in 201-214.

  The effectiveness of the present invention was confirmed.

Example 3
Sample No. 1 of Example 1 When producing 101, the coating liquid for the surface layer was applied under the same conditions except that the velocity of the gas taken in from the gas inlet of the scattered coating liquid collecting device was changed as shown in Table 4, and the second drying unit A recording material having a surface layer was produced by drying, and sample No. 301 to 306.

(Evaluation)
Each prepared sample No. Table 4 shows the results of evaluation according to the following evaluation methods and evaluation ranks attached to 301 to 306 and attached to droplet unevenness and density variation (coating width direction) accompanying the drop of the droplet. The droplet unevenness was evaluated according to the same evaluation method and the same evaluation rank as in Example 1.

Measurement of density variation The density of 10 points at 100 m intervals in the coating direction with a total length of 1000 m was scanned with the density meter in the width direction in the width direction, and the reflection density was measured with the density meter X-Rite 310TR manufactured by X-Rite. The absolute value of the difference in the minimum concentration was expressed as a percentage of the average concentration.

Evaluation rank of density variation ◎: Density variation is less than 2% ○: Density variation is 2% or more and less than 5% △: Density variation is 5% or more and less than 10% ×: Density variation exceeds 10%

  The effectiveness of the present invention was confirmed.

Example 4
Sample No. 1 of Example 1 When producing 101, the coating solution for the surface layer was applied under the same conditions except that the reduced pressure inside the casing of the scattered coating solution collecting apparatus was changed as shown in Table 5, and dried in the second drying section. A recording material having a surface layer was prepared and sample no. 401 to 407.

(Evaluation)
Each prepared sample No. Table 5 shows the results of evaluation according to the following evaluation methods and evaluation ranks attached to 401 to 407 and attached to the liquid drop unevenness and the coating rate accompanying the drop of the liquid drop. The droplet unevenness was evaluated according to the same evaluation method and the same evaluation rank as in Example 1.

Evaluation method of coating rate When the pressure inside the casing of the scattered coating solution recovery device is 0, the recording material having the surface layer is coated with the coating solution for the surface layer under the same conditions and dried in the second drying section. Was prepared as a reference sample. An average concentration of 100 was obtained by measuring the concentration over the entire width of the reference sample. The entire width of each sample was measured to determine the average concentration, and the coating rate was determined by the following calculation method.

Application rate (%) = average concentration of each sample / average concentration of reference sample × 100
Evaluation rank of the coating rate (%) ○: The coating rate is 90% or more Δ: The coating rate is 80% or more and less than 90% ×: The coating rate is less than 80%

  The effectiveness of the present invention was confirmed.

It is a schematic diagram which shows an example of the coating production line which has arrange | positioned the curtain spray coating device. 2 is a schematic enlargement of a portion indicated by X in FIG. 1. It is a schematic plan view of the curtain spray coating apparatus shown by (a) of FIG. FIG. 4 is a schematic plan view of the curtain spray coating apparatus shown in FIG. 3 in which a scattering coating liquid recovery apparatus having a different shape and position of the gas inlet is provided. It is a schematic diagram which shows the state of the droplet of the suction chamber of the scattering coating liquid collection | recovery apparatus at the time of spray coating. It is a schematic diagram which shows the movement state of the coater at the time of the application | coating start of the spray coating device shown by (a) of FIG. 2, and a scattering coating liquid collection | recovery apparatus. It is a schematic exploded perspective view of the curtain spray coater shown in FIGS.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coating production line 2 Feeding part 201 Support body 203 Ink absorption layer 204 Surface layer 3 1st coating part 4 Cooling part 5 Drying part 6 2nd coating part 601 Curtain spray coating apparatus 601a Coater 601b Spattering coating liquid collection apparatus 601b1 main body 601b2 Top plate 601b8 Suction chamber 601b9 Suction tube 601b11 Gas inlet 7 Winding part G, G ′, G ″ Length H, H ′, H ″ Width I Distance

Claims (21)

On the at least one ink absorbing layer formed on the support which is supported by the backup roll and continuously conveyed, the ink absorbing layer is provided by a curtain spray coating device disposed at a position intersecting the conveying direction of the support. In the curtain spray coating method for the surface layer of inkjet recording paper, the surface layer is formed by curtain spray coating the coating liquid over the entire width in the width direction.
The curtain spray coating apparatus has a curtain spray coater, a scattering coating liquid recovery apparatus, and a moving means.
The scattering coating liquid recovery device has a housing structure having an opening on the curtain spray coater side, a side plate having a suction port, a top plate having a gas intake port, and a bottom plate,
A curtain spray coating method for a surface layer, characterized in that the inside of the housing is decompressed through the suction port during curtain spray coating, and the scattering coating liquid is collected while coating the gas from the gas intake port. . The splash coating liquid recovery device has an opening abutting against a wall surface in the width direction of the curtain spray coater and a bottom plate disposed so as to be close to the outer peripheral surface of the backup roll, and the upstream and downstream sides of the curtain spray coater. The surface layer curtain spray coating method according to claim 1, wherein the surface layer curtain spray coating method is provided. 3. The surface layer curtain spray coating method according to claim 1, wherein the gas inlet is disposed at least near the tip of the top plate in parallel with the wall surface in the width direction of the curtain spray coater. 4. The gas inlet according to claim 1, wherein the gas inlet is a long hole having a length of 1 to 50 mm and 90 to 120% of a width of an object to be coated provided in a width direction of the curtain spray coater. The surface layer curtain spray coating method according to claim 1. 4. The gas inlet according to claim 1, wherein square holes having a length of 1 to 500 mm and a width of 1 to 50 mm are arranged at intervals of 1 to 50 mm. Curtain spray coating method for surface layer. The method of spraying a surface layer according to any one of claims 1 to 3, wherein the gas inlet has round holes with a diameter of 1 to 50 mm arranged at intervals of 1 to 100 mm. . The method for applying a surface layer curtain spray according to any one of claims 1 to 6, wherein the velocity of the gas introduced from the gas inlet is 5 to 50 m / sec. The surface layer curtain spray coating method according to any one of claims 1 to 7, wherein a reduced pressure inside the casing at the time of the curtain spray coating is 50 to 1000 Pa. When the curtain spray coater moves between the application position and the standby position, the scattering coating liquid recovery device moves between the arrangement position and the standby position in accordance with the movement of the curtain spray coater. The curtain spray coating method for a surface layer according to any one of claims 1 to 8. The surface layer curtain spray coating according to any one of claims 1 to 9, wherein the ink absorbing layer is composed of a porous layer containing at least one inorganic fine particle and a binder. Method. Coating the surface layer of an ink jet recording paper by coating the coating liquid with a curtain spray on the entire width in the width direction of at least one ink absorbing layer formed on a support that is continuously supported by a backup roll. Curtain spray application equipment for
The curtain spray coating apparatus has a curtain spray coater, a scattering coating liquid recovery apparatus, and a moving means.
The scattering coating liquid recovery device has a structure of a housing having an opening on the curtain spray coater side, a side plate having a suction port, a top plate having a gas intake port, and a bottom plate,
Curtain spray for surface layer application, wherein the inside of the housing can be decompressed through the suction port during curtain spray application, and gas can be taken in from the gas intake port and the scattered coating liquid can be collected. Coating device. The splash coating liquid recovery device is arranged such that the opening is brought into contact with the wall surface in the width direction of the curtain spray coater and the bottom plate is disposed so as to be close to the outer peripheral surface of the backup roll, and the upstream side and the downstream side of the curtain spray coater The curtain spray coating apparatus for coating a surface layer according to claim 11, wherein the curtain spray coating apparatus is disposed respectively on the surface layer. 13. The curtain spray coating apparatus for coating a surface layer according to claim 11 or 12, wherein the gas inlet is disposed at least near the tip of the top plate in parallel with the wall surface in the width direction of the curtain spray coater. . 14. The gas inlet according to claim 11, wherein the gas inlet is a long hole having a length of 1 to 50 mm and 90 to 120% of a width of an object to be coated provided in a width direction of the curtain spray coater. The curtain spray coating apparatus for surface layer application | coating of any one. 14. The gas intake port according to claim 11, wherein square holes having a length of 1 to 500 mm and a width of 1 to 50 mm are arranged at intervals of 1 to 50 mm. Curtain spray coating device for surface layer coating. The curtain spray for surface layer application according to any one of claims 11 to 13, wherein the gas inlet has round holes with a diameter of 1 to 50 mm arranged at intervals of 1 to 100 mm. Coating device. The curtain spray coating apparatus for surface layer coating according to any one of claims 11 to 16, wherein a speed of a gas taken in from the gas inlet is 5 to 50 m / sec. 18. The curtain spray coating apparatus for surface layer coating according to claim 11, wherein a reduced pressure inside the casing at the time of the curtain spray coating is 50 to 1000 Pa. When the curtain spray coater moves between the application position and the standby position, the scattering coating liquid recovery device moves between the arrangement position and the standby position in accordance with the movement of the curtain spray coater. The curtain spray coating device for surface layer coating according to any one of claims 11 to 18. The curtain for coating a surface layer according to any one of claims 11 to 19, wherein the ink absorption layer is composed of a porous layer containing at least one layer of inorganic fine particles and a binder. Spray application device. An ink jet recording paper produced by the curtain spray coating method for a surface layer according to any one of claims 1 to 10.

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