JP2022133734A - Liquid coating device - Google Patents

Abstract

To provide a liquid coating device capable of evenly applying liquid even to a coating medium having low wettability such as a nonflammable wood, and capable of suppressing excessive application of liquid.SOLUTION: A liquid coating device includes: an application roller 10 that applies liquid to a surface of an application medium M; and a sponge roller 11 that slides on the surface of the application medium M by relatively moving to the application medium M while contacting with the surface of the application medium M to which the liquid has been applied by the application roller 10, with a predetermined pressure, and absorbs some of the liquid applied to the application medium M by the application roller 10.SELECTED DRAWING: Figure 1

Description

The present invention relates to a liquid coating device that applies liquid to a coating medium.

Conventionally, noncombustible wood has been proposed which is produced by permeating and injecting a boron-based (borax, boric acid, etc.) or phosphoric acid-based (ammonium phosphate, etc.) noncombustible agent into wood. Such incombustible wood can prevent fire by using it as a building member, for example.

JP 2019-042671 A JP 2009-73117 A

Here, when the incombustible wood is used as a building member, for example, as described above, it is preferable if the incombustible wood can be decorated with ink or the like, because of its wide range of applications.

However, wood, which is the raw material for noncombustible wood, has pipes (conduits) that play a role in allowing water to pass through. These tubes also exist in incombustible wood. For example, when direct inkjet printing is performed using water-based ink, the interior of the tubes is exposed on the wood surface processed into a plate shape, so bleeding occurs along the tubes. , fine line reproducibility is reduced.

Therefore, in order to suppress the bleeding as described above, a method of applying a surface treatment liquid to the surface of wood to form a surface treatment layer and performing ink jet printing on the surface treatment layer is conceivable.

However, noncombustible wood has a low wettability, which is a characteristic of wood. is repelled on the surface without penetrating. Moreover, since noncombustible wood tends to have a high contact angle, it is difficult to evenly apply a surface treatment liquid to the surface of noncombustible wood.

Further, in Patent Document 2, it is proposed to press the surface of the wood with a friction roller to instantaneously heat the surface of the wood to a high temperature and a high pressure, and then spray the liquid. Application also has the same problem as spray jetting.

On the other hand, in order to evenly apply the surface treatment liquid to the surface of noncombustible wood, it is possible to increase the amount of surface treatment liquid, but in the case of noncombustible wood, excessive application of the surface treatment liquid causes efflorescence. is known. The efflorescence phenomenon will be described in detail later.

It is an object of the present invention to provide a liquid applicator capable of uniformly applying a liquid even to an application medium having low wettability such as incombustible wood, and capable of suppressing excessive application of the liquid. aim.

The liquid applying apparatus of the present invention includes an applying section that applies a liquid to the surface of a coating medium, and a liquid-applying medium that is in contact with the surface of the coating medium to which the liquid has been applied by the applying section with a predetermined pressure. a sliding part that moves dynamically to slide on the surface of the application medium and absorbs part of the liquid applied to the application medium by the application part.

According to the liquid coating apparatus of the present invention, the coating part that applies the liquid to the surface of the coating medium, and the coating part that contacts the surface of the coating medium coated with the liquid by the coating part with a predetermined pressure. and a sliding portion that moves relatively to slide on the surface of the coating medium and absorbs a part of the liquid applied to the coating medium by the coating portion. Even with a coating medium having low resistance, the liquid can be uniformly coated, and excessive liquid coating can be suppressed.

1 is a diagram showing a schematic configuration of an embodiment of a liquid coating apparatus of the present invention; FIG. FIG. 2 is a view of the liquid coating device shown in FIG. 1 viewed from the direction of arrow A; A diagram showing an example of the configuration of the cleaning unit The figure which shows the other example of a structure of a cleaning part. FIG. 1 is an external view showing a schematic configuration of an inkjet printing apparatus using the liquid coating apparatus shown in FIG. Diagram showing the internal configuration of the shuttle unit Block diagram showing the configuration of the control system of the inkjet printer Explanatory diagram for explaining the operation of the inkjet printing apparatus shown in FIG.

Hereinafter, one embodiment of the liquid coating device of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a liquid coating device 1 according to this embodiment. 2 is a side view of the liquid coating device 1 shown in FIG. 1 as viewed in the direction of arrow A. As shown in FIG.

The liquid coating device 1 of this embodiment includes a coating roller 10, a sponge roller 11, and a cleaning section 12, as shown in FIGS. In this embodiment, the application roller 10 corresponds to the application portion of the invention, and the sponge roller 11 corresponds to the sliding portion of the invention.

The application roller 10 applies liquid to the surface of the application medium M. As shown in FIG. In this embodiment, non-combustible wood is used as the coating medium M, and a surface treatment liquid that is applied to the non-combustible wood before printing is used as the coating liquid. The noncombustible wood and the surface treatment liquid will be detailed later. In the present invention, the application medium M and the liquid applied to the application medium are not limited to noncombustible wood and the surface treatment liquid.

The application roller 10 is a roller extending in the width direction of the application medium M, and moves in a direction orthogonal to the width direction of the application medium M, as shown in FIG. A liquid to be applied is supplied directly to the surface of the application medium M or to the application roller 10 from a liquid supply unit (not shown). Then, the application roller 10 comes into contact with the application medium M and moves in the arrow Y direction shown in FIG. The liquid is applied onto the application medium M by the rotation of the application roller 10 . At this time, the amount of the liquid applied onto the application medium M is a sufficient amount that the surface of the application medium M can be uniformly applied.

The sponge roller 11 moves relative to the application medium M and slides on the surface of the application medium M while contacting the surface of the application medium M coated with the liquid with a predetermined pressure. Specifically, the sponge roller is a roller that extends in the width direction of the application medium M and moves in a direction orthogonal to the width direction of the application medium M, like the application roller 10 . However, although the sponge roller 11 is in contact with the surface of the application medium M, unlike the application roller 10, it is configured not to rotate due to frictional force with the application medium M. FIG. The sponge roller 11 slides on the surface of the application medium M by moving in the direction of the arrow Y shown in FIG. 2 without rotating as described above. That is, the sponge roller 11 moves in the arrow Y direction while rubbing the surface of the application medium M with the same range of the surface of the sponge roller 11 . Note that the sponge roller 11 rotates during a cleaning operation by the cleaning unit 12, which will be described later, and the cleaning operation will be described in detail later.

The sponge roller 11 includes a sponge roller main body 11a formed by forming a sponge into a roller shape, a supporting member 11b supporting the sponge roller main body 11a from above, and a spring portion 11c pressing the supporting member 11b from above. .

The support member 11b is connected to both ends of the rotating shaft of the sponge roller body 11a. The support member 11b supports the sponge roller body 11a so that it does not rotate when the sponge roller body 11a is slid on the surface of the application medium M as described above. Rotatable support.

The spring portion 11c has a plurality of springs that urge the support member 11b downward, and the urging of the support member 11b by the springs applies pressure from above to the rotating shaft of the sponge roller main body 11a. As a result, the sponge surface of the sponge roller main body 11a is pressed against the application medium M with a predetermined pressure.

By sliding the sponge roller 11 on the surface of the application medium M while being pressed with a predetermined pressure, the liquid applied by the application roller 10 can be pressed against the surface of the application medium M. The liquid can be uniformly applied even to a coating medium M having high water repellency such as incombustible wood.

The pressure with which the sponge surface of the sponge roller body 11a presses the surface of the application medium M is preferably higher than the pressure with which the application roller 10 presses the surface of the application medium M. FIG. Thereby, the sponge roller 11 can be pressed against the application medium M with a sufficient pressure, and the liquid applied to the application medium M can be pushed into the application medium M.

Moreover, since the sponge roller 11 can absorb a part of the liquid applied to the application medium M by the application roller 10, the excess applied liquid can be absorbed. For example, when the coating medium M is noncombustible wood, the efflorescence phenomenon can be suppressed by absorbing excessively applied liquid (surface treatment liquid).

Here, the efflorescence phenomenon will be described. Incombustible wood is a member manufactured by permeating and injecting a boron-based (eg, borax, boric acid, etc.) or phosphoric acid-based (eg, ammonium phosphate, etc.) incombustible agent into the wood.

As described above, when non-combustible wood is manufactured by non-combustible treatment with a boron-based or phosphoric acid-based non-combustible agent, an auxiliary agent is added. As a result of the application of the treatment liquid, it is known from experiments by the applicant that efflorescence occurs in which the surface becomes white due to precipitated crystals. Auxiliary agents are agents used to increase the solubility of boron or phosphate in water and promote the penetration of noncombustible agents into noncombustible wood. For example, ammonium salts such as diammonium phosphate are used. Since such an auxiliary agent has a high affinity with water molecules and reacts with water contained in the surface treatment liquid, the above-described efflorescence phenomenon occurs.

If printing is performed on the incombustible wood with the efflorescence occurring, the quality of the printed image will deteriorate due to the precipitated crystals. In addition, the crystals precipitated by the efflorescence phenomenon cannot be easily removed from the noncombustible wood, and if removed forcibly, marks are left on the surface and the quality of the decorative article is deteriorated.

On the other hand, the applicant's experiments have revealed that the presence or absence of the efflorescence depends on the amount of the surface treatment liquid applied to the noncombustible wood. Therefore, it is preferable to adjust the amount of the surface treatment liquid applied to the incombustible wood to an amount that does not cause the efflorescence.

According to the sponge roller 11 of the present embodiment, the excessively applied surface treatment liquid can be absorbed as described above, so that the efflorescence phenomenon can be suppressed.

The pressure conditions under which the sponge roller 11 is pressed against the incombustible wood, the pressure conditions under which the recovery roller 12a of the cleaning unit 12, which will be described later, are pressed against the sponge roller 11, and the surface treatment liquid from the sponge roller 11 (dry state of the sponge roller 11) and the like are set so that the non-combustible wood does not absorb the amount of water that causes the efflorescence phenomenon.

For example, the pressure when the sponge roller 11 is pressed against the incombustible wood is preferably 5 kPa or more. The amount of the surface treatment liquid applied to the noncombustible wood is preferably 50 g/m ² or less. The amount of the surface treatment liquid is the amount measured immediately after applying the surface treatment liquid to the noncombustible wood. Also, the absorbency of the sponge roller 11 is preferably 0.44 g/cm ³ or more. The water absorbency of the sponge roller 11 is an index indicating the amount per unit volume of the surface treatment liquid that the sponge roller can absorb and retain inside.

Next, the cleaning unit 12 cleans the surface of the sponge roller main body 11a while recovering the liquid absorbed by the sponge roller 11. As shown in FIG. In this embodiment, the sponge roller 11 slides on the surface of the application medium M as described above. This may reduce the absorbency of the main body 11a or cause secondary contamination. Therefore, in this embodiment, the surface of the sponge roller main body 11a is cleaned by the cleaning section 12 as described above. As a result, it is possible to prevent deterioration of absorbency and secondary contamination of the sponge roller main body 11a.

Further, the cleaning section 12 collects the liquid absorbed by the sponge roller main body 11a as described above. As a result, the cleaning unit 12 can restore the absorbency of the sponge roller body 11a while removing dirt from the surface of the sponge roller body 11a.

The part where the cleaning part 12 contacts the sponge roller 11 is preferably on the opposite side of the application roller 10 (application part) with respect to a vertical plane passing through the central axis of the sponge roller 11. It is preferably above a horizontal plane passing through the central axis of 11 . By locating the portion where the cleaning portion 12 contacts the sponge roller 11 as described above, the liquid absorbed by the sponge roller main body 11a can be easily collected without dripping.

FIG. 3 is a diagram showing an example of the configuration of the cleaning section 12. As shown in FIG. The cleaning section 12 shown in FIG. 3 includes a recovery roller 12a that contacts the sponge roller body 11a, and a liquid receiving section 12b.

The collecting roller 12a is a roller extending along the sponge roller main body 11a. By contacting the sponge roller body 11a, the recovery roller 12a adheres dirt adhering to the surface of the sponge roller body 11a and part of the liquid absorbed by the sponge roller body 11a to the surface of the recovery roller 12a. As a result, the collecting roller 12a collects dirt adhering to the surface of the sponge roller body 11a and part of the liquid absorbed by the sponge roller body 11a.

The collection roller 12a rotates in the opposite direction (direction of arrow C in FIG. 3) to the direction of rotation of the sponge roller main body 11a (direction of arrow B in FIG. 3). and the liquid L fall downward due to its own weight or squeezing, or a combination thereof.

The liquid receiver 12b receives and stores the dirt and the liquid L dropped from the recovery roller 12a as described above. The hatched portion in FIG. 3 is the liquid L stored in the liquid receiving portion 12b.

Note that the configuration of the cleaning unit 12 is not limited to the configuration shown in FIG. 3 . FIG. 4 is a diagram showing another configuration of the cleaning unit 12. As shown in FIG. The cleaning section 12 shown in FIG. 4 includes a spatula section 12c instead of the collecting roller 12a shown in FIG.

The spatula portion 12c includes a rectangular plate member extending along the sponge roller main body 11a. The spatula portion 12c is configured such that one end portion having a long side of a rectangular plate member contacts the surface of the sponge roller main body 11a.

The distance between the spatula 12c and the sponge roller main body 11a is such that part of the liquid L absorbed by the sponge roller main body 11a is removed by sliding one end of the plate member of the spatula 12c on the surface of the sponge roller main body 11a. It is set to a distance that is scraped out by the plate member. That is, during the cleaning operation of the sponge roller 11 by the cleaning unit 12, the sponge roller body 11a rotates in the direction of arrow B shown in FIG. Dirt and liquid L absorbed near the surface are scraped out. Dirt and liquid L scraped out from sponge roller main body 11a fall downward due to their own weight, and are received and stored by liquid receiving portion 12b. The hatched portion in FIG. 4 is the liquid L stored in the liquid receiving portion 12b.

Next, an example of the operation of the liquid coating device 1 of this embodiment will be described.

First, the liquid coating device 1 is installed at the edge of the coating medium M. As shown in FIG. Then, the liquid applying device 1 starts moving in the direction of arrow Y shown in FIG.

Then, both the application roller 10 and the sponge roller 11 move in the arrow Y direction while maintaining a constant distance. As a result, the application roller 10 first applies the liquid to the surface of the application medium M, and then the sponge roller 11 slides on the surface of the application medium M to which the liquid has been applied. is pressed against the surface of the application medium M by the sponge roller 11 . Thereby, the liquid can be uniformly applied to the surface of the application medium M as described above. Also, the sponge roller 11 can absorb excess liquid.

Then, when the liquid applying device 1 has moved to the other end of the application medium M, the operation of applying the liquid to the application medium M ends. Then, the liquid coating device 1 moves upward to a position separated from the coating medium M, and then returns to the initial position.

Next, when returning to the initial position, the liquid applying apparatus 1 rotates the sponge roller main body 11a in the direction of arrow B shown in FIG. The cleaning operation by the cleaning unit 12 is performed by rotating the cleaning unit 12 to the left.

By this cleaning operation, part of the dirt adhering to the surface of the sponge roller body 11a and the absorbed liquid is recovered by the recovery roller 12a as described above. The amount of rotation of the sponge roller body 11a in the cleaning operation is such that at least the range of the sponge roller body 11a from which dirt and liquid have been collected by the cleaning unit 12 moves to the next contact position with the application medium M. set. FIG. 2 shows the state after the sponge roller main body 11a rotates in the cleaning operation. , indicates the range where the liquid remains without being recovered by the recovery roller 12a. In this way, by recovering part of the liquid absorbed by the sponge roller body 11a by rotating the sponge roller body 11a, it is possible to restore the absorbency of the sponge roller body 11a with a simple configuration and control. . Further, the sponge roller body 11a can be repeatedly used only by rotating the sponge roller body 11a.

In the liquid applying apparatus 1 of the above-described embodiment, the application roller 10 applies the liquid to the surface of the application medium M. Alternatively, the liquid may be applied by spraying the liquid onto the surface of the application medium M, for example.

Next, an inkjet printing apparatus 20 equipped with the liquid applying apparatus 1 of the above embodiment will be described. FIG. 5 is a configuration diagram of an inkjet printing apparatus 20 including the liquid coating device 1 of the above embodiment. In the description of the embodiment shown below, the up, down, left, right, front and back directions indicated by arrows in FIG.

The inkjet printing apparatus 20 includes a shuttle base unit 2, a flatbed unit 3, a shuttle unit 4, and a pretreatment unit 6, as shown in FIG. The pretreatment unit 6 accommodates the liquid coating device 1 of the above-described embodiment.

The shuttle base unit 2 supports the shuttle unit 4 and the preprocessing unit 6, and moves the shuttle unit 4 and the preprocessing unit 6 in the front-rear direction (sub-scanning direction). Specifically, the shuttle base unit 2 includes a pedestal 31, sub-scanning drive guides 33A and 33B, and a sub-scanning drive motor 32 (see FIG. 7).

The pedestal part 31 is formed in a rectangular frame shape and supports the shuttle unit 4 and the pretreatment unit 6 . Sub-scanning drive guides 33A and 33B extending in the front-rear direction are formed on the left and right frames of the mount 31, respectively. The sub-scanning drive guides 33A, 33B guide the shuttle unit 4 and the preprocessing unit 6 so as to move in the front-rear direction. The sub-scanning drive motor 32 moves the shuttle unit 4 and the preprocessing unit 6 in the front-rear direction.

The flatbed unit 3 supports the application medium M described above. The flatbed unit 3 is arranged in a rectangular parallelepiped concave portion formed inside the gantry portion 31 of the shuttle base unit 2 . The flatbed unit 3 has a medium mounting surface 3a, which is a horizontal surface on which the coating medium M is mounted. The flatbed unit 3 has a hydraulic drive mechanism (not shown) and the like, and is configured to adjust the height of the medium mounting surface 3a.

The shuttle unit 4 performs print processing on the coating medium M. As shown in FIG. FIG. 6 is a diagram showing a schematic configuration of the shuttle unit 4. As shown in FIG.

As shown in FIG. 6, the shuttle unit 4 includes a housing 41, a main scanning drive guide 42, a main scanning drive motor 43 (see FIG. 7), a head elevation guide 44, and a head elevation motor 45 (see FIG. 7). ) and a head unit 46 .

The housing 41 houses each part such as the head unit 46 . The housing 41 is formed in a portal shape so as to straddle the flatbed unit 3 in the left-right direction. The housing 41 is supported by the pedestal portion 31 of the shuttle base unit 2 and configured to be movable along the sub-scanning drive guides 33A and 33B.

The main scanning drive guide 42 guides the head unit 46 to move in the horizontal direction (main scanning direction). The main scanning drive guide 42 is formed of an elongated member extending in the left-right direction. The head unit 46 is horizontally moved by the main scanning drive motor 43 .

The head elevation guide 44 guides the head unit 46 to move vertically. The head elevating guide 44 is formed of a vertically elongated member. The head elevation guide 44 is configured to be movable in the horizontal direction along the main scanning drive guide 42 together with the head unit 46 . The head unit 46 is vertically moved by a head lifting motor 45 .

The head unit 46 performs printing processing by ejecting ink onto the substrate while moving in the horizontal direction along the main scanning drive guide 42 as described above. The head unit 46 has four inkjet heads 51, as shown in FIG.

The four inkjet heads 51 are arranged side by side in the horizontal direction. The four inkjet heads 51 eject inks of different colors (eg, cyan, black, magenta and yellow). An ink supply pipe 53 for supplying ink is connected to each of the four inkjet heads 51 .

Returning to FIG. 5, the pretreatment unit 6 applies a surface treatment liquid to the application medium M to perform pretreatment. As described above, the liquid coating device 1 of the above-described embodiment is accommodated in the pretreatment unit 6, and the lateral direction of the inkjet printing device 20 is the direction in which the coating roller 10, the sponge roller 11, and the like extend. Each part of the liquid applying apparatus 1 is arranged so as to be. Also, the application roller 10 is arranged on the front side of the inkjet printing device 20 and the sponge roller 11 is arranged on the rear side of the inkjet printing device 20 .

The preprocessing unit 6 is supported by the pedestal portion 31 of the shuttle base unit 2 and is configured to be movable along sub-scanning drive guides 33A and 33B. The pretreatment unit 6 sequentially applies the surface treatment liquid to a predetermined range on the coating medium M below it by moving in the sub-scanning direction (Y direction).

FIG. 7 is a block diagram showing the configuration of the control system of the inkjet printer 20 of this embodiment. The inkjet printing apparatus 20 operates each section to be controlled shown in FIG. 7 according to the control signal from the printing control apparatus 15 .

The print control device 15 and the inkjet printer 20 are connected by a communication line such as a LAN (Local Area Network) or Internet line, and are configured to be able to communicate with each other.

The print control device 15 is composed of a computer including a CPU (Central Processing Unit), a semiconductor memory, a hard disk, and the like. The print control device 15 executes a print control program stored in advance in a storage medium such as a semiconductor memory or a hard disk based on an input print job or the like, and operates an electric circuit to operate each unit shown in FIG. Control.

Next, the operation of the inkjet printing apparatus 20 of this embodiment will be described with reference to FIGS. 8A to 8D. 8A to 8D are views of the inkjet printer 20 shown in FIG. 5 as viewed from the left side.

First, as shown in FIG. 8A, the coating medium M is placed on the flatbed unit 3 . At this time, the shuttle unit 4 and the pretreatment unit 6 are arranged at the initial positions on the frontmost side, as shown in FIG. 8A. Then, the print control device 15 drives the sub-scanning drive motor 32, whereby the shuttle unit 4 and the preprocessing unit 6 start moving backward (in the direction of the arrow shown in FIG. 8A) from the initial position shown in FIG. 8A. and moves to the print start position shown in FIG. 8B.

Next, as shown in FIG. 8C, the print control device 15 moves the pretreatment unit 6 forward (in the direction of the arrow shown in FIG. 8C), operates the liquid coating device 1 in the pretreatment unit 6, A surface treatment liquid is applied to the application medium M to perform pretreatment.

Then, after the surface treatment liquid is applied to the coating medium M by the pretreatment unit 6, the coating medium M is once transported to a drying device (not shown) to be dried. After the drying process in the drying device is completed, the coated medium M is set in the inkjet printing device 20 again, and the printing control device 15 controls the sub-scanning drive motor 32 to move the shuttle unit 4 as shown in FIG. 8D. The printing process is performed while moving forward (in the direction of the arrow shown in FIG. 8D).

Specifically, the print control device 15 first controls the main scanning drive motor 43 to move the head unit 46 in the main scanning direction while the shuttle unit 4 is located at the print start position. Then, the ink jet head 51 of the head unit 46 ejects ink according to a control signal based on the print image, thereby performing printing for one pass.

After printing for one pass is completed, the print control device 15 controls the sub-scanning drive motor 32 to move the shuttle unit 4 forward to the printing position for the next pass. The print control device 15 forms a print image on the coating medium M by alternately repeating this one-pass printing and the movement of the shuttle unit 4 .

Then, when the printing process for one sheet is completed, the shuttle unit 4 and the preprocessing unit 6 are placed at the initial positions again, as shown in FIG. 8D.

Next, with the pretreatment unit 6 arranged at the initial position, the cleaning section 12 in the pretreatment unit 6 performs the cleaning operation described above.

In the inkjet printing apparatus 20 of the above-described embodiment, the drying device is configured differently, but a drying unit may be provided in the inkjet printing apparatus 20 like the pretreatment unit 6, and the substrate may be scanned by the drying unit. You may make it dry-process by.

Next, the surface treatment liquid used in the liquid coating apparatus 1 of the above embodiment will be described in detail.

The surface treatment liquid preferably contains at least water, a colorant-fixing component and a surface tension adjuster. The coloring material-fixing component is preferably a cationic water-dispersible resin, and preferably contains large particles having a median diameter of 1 μm or more and 10 μm or less as measured by a dynamic light scattering method. Furthermore, it is more preferable to contain small particles having a median diameter of less than 1 μm as measured by a dynamic light scattering method.

The surface treatment liquid of the present embodiment is particularly preferably used as a surface treatment liquid before printing using non-UV curable ink (for example, water-based ink). By using the surface treatment liquid of the present embodiment in advance before printing, and then forming a printed image with an inkjet ink, the wetting and spreading of the ink is controlled, thereby making it difficult to spread, good fine line reproducibility, and color development. A good printed image can be formed.

The cationic water-dispersible resin particles are positively charged resin particles whose surfaces are positively charged. It is capable of forming an emulsion of the type. The resin may have a cationic functional group present on the particle surface like a self-emulsifying resin, or may be surface-treated such as by attaching a cationic dispersant to the resin particle surface.

Cationic functional groups are typically primary, secondary or tertiary amino groups, pyridine groups, imidazole groups, benzimidazole groups, triazole groups, benzotriazole groups, pyrazole groups, benzopyrazole groups and the like. and the cationic dispersant is a primary, secondary, tertiary or quaternary amino group-containing acrylic polymer, polyethyleneimine, cationic polyvinyl alcohol resin, cationic water-soluble multi-branched polyester amide resin, and the like.

The surface charge amount of the resin particles can be evaluated with a particle charge meter. By measuring the amount of anions or cations required to neutralize the sample, the amount of surface charge can be calculated. Specifically, the surface charge amount is preferably +300 μeq/g or more. As the particle charge meter, a colloidal particle charge meter Model CAS manufactured by Nihon Luft Co., Ltd. or the like can be used.

As the water-dispersible resin, it is preferable to use a resin that forms a transparent coating film. Further, when manufacturing the treatment liquid, it can be blended as an oil-in-water type resin emulsion.

Representative examples include ethylene-vinyl chloride copolymer resin, (meth)acrylic resin, styrene-maleic anhydride copolymer resin, urethane resin, vinyl acetate-(meth)acrylic copolymer resin, vinyl acetate-ethylene copolymer resin. Coalesced resins, resin emulsions thereof, and the like are included. Here, "(meth)acrylic resin" indicates both acrylic resin and methacrylic resin. These resins may be used alone or in combination of multiple types. As will be described later, a resin emulsion in which these resins are combined may be used. As noted above, these resins can be given a positive surface charge by introducing cationic functional groups or by surface treatment with cationic dispersants and the like.

The particle size of the resin particles is not particularly limited, and particles with different particle sizes can be used in any combination. However, from the viewpoint of being likely to remain on the surface of the noncombustible wood, it is preferable to contain particles having a median diameter (average particle diameter) of 1 μm or more as measured by a dynamic light scattering method. Moreover, the average particle size of the resin particles is preferably 10 μm or less, so that the resin particles can permeate recesses and voids on the surface of the noncombustible wood while making use of the properties of the noncombustible wood as wood.

That is, in the noncombustible wood, by setting the median diameter (average particle diameter) of the resin particles to 1 μm or more and 10 μm or less, it is possible to efficiently form the surface treatment layer following the size of the tube of the noncombustible wood. can. In wood, in particular, the tube size (average diameter) differs depending on whether it is a coniferous tree or a broad-leaved tree. For example, the average diameter of ash wood, which is a ring-porous hardwood, is about 260 μm, and the average diameter of maple wood, which is a broad-leaved wood, is about 60 μm. On the other hand, Japanese cypress, which is a coniferous tree, has an average diameter of about 10 μm. As described above, wood has different pore sizes depending on the tree species, and since it is a natural product, no two substrates have exactly the same pore distribution. By doing so, it is possible to form a surface treatment layer even on a base material with irregular voids such as wood, without deteriorating the original function of the base material (hygroscopicity in wood).

Furthermore, the surface treatment liquid preferably also contains small particles having a median diameter (average particle diameter) of less than 1 μm as measured by a dynamic light scattering method. This can further improve the water resistance of the ink layer in addition to the image quality described above.

If the ratio of large particles to small particles is too small, the fixing property will be insufficient. Therefore, it is preferable that the weight ratio of the small particles to the large particles is about 0.1 to 1.5. In this specification, "weight" and "mass" are used interchangeably.

The average particle size of the resin particles is the volume-based particle size value (median size) in the particle size distribution measured by the dynamic light scattering method. As a dynamic light scattering type particle size distribution measuring device, a nanoparticle analyzer nano Partica SZ-100 (Horiba, Ltd.) or the like is used. It can be diluted and measured at 25°C.

In the surface treatment liquid or the ink described later, the resin particles may exist in the state of independent fine particles or in the state of aggregates in which independent fine particles are aggregated. Let the median diameter measured by the method be the "average particle diameter".

It should be noted that the average particle diameter of the resin particles is preferably measured in the raw material emulsion state before preparation of the surface treatment liquid or ink, because in the case of the ink, the influence of the coloring material (pigment particles) can be eliminated. The measured value can be used as the average particle size of the present embodiment.

The average particle size of the large particles is more preferably 7 μm or less, more preferably 5 μm or less. More preferably, the average particle diameter of the small particles is 500 nm or less. Although the lower limit of the average particle diameter is not particularly limited, it is preferably about 5 nm or more, more preferably 10 nm or more, from the viewpoint of storage stability of the surface treatment liquid.

Furthermore, it is preferable that the large particles and the small particles have two peaks in the particle size distribution when the average particle size is measured by mixing them, that is, they have different peak values.

Also, the large particles and the small particles may have other differences in addition to the difference in average particle size. For example, the large particles preferably have a minimum film-forming temperature (MFT) of 70°C or higher, while the small particles preferably have an MFT of less than 70°C. This MFT is the temperature required for the emulsion to form a film (film formation), and can be measured according to JIS K6828-2. Here, water-dispersible resins that do not form a film even at 70°C are included in water-dispersible resins having an MFT of 70°C or higher.

More preferably, the MFT of the large particles is 100° C. or higher, and the MFT of the small particles is 50° C. or lower. Particularly, since it is preferable to form the film at room temperature for the small particles, the MFT is even more preferably 40° C. or lower. .

Also, the difference between the MFT of the large particles and the MFT of the small particles is preferably 30° C. or higher, more preferably 50° C. or higher, and even more preferably 100° C. or higher.

The molecular structures of the large particles and the small particles may be the same, but different ones may also be used.

As large particles, for example, a polymer having an anionic functional group such as a carboxy group or a sulfo group is combined with a polymer having a cationic functional group such as an amino group or an amide group. It is also preferable to use composite organic particles having a core-shell structure in which the core portion is an anionic polymer and the shell portion is a cationic polymer.

Examples of the anionic polymer of the composite organic particles include polymers containing (meth)acrylic acid as repeating units, more specifically styrene-(meth)acrylic acid copolymers. A vinyl compound other than styrene and (meth)acrylic acid that can be copolymerized therewith may also be included.

Examples of the cationic polymer (basic polymer) of the composite organic particles include polymers containing nitrogen-containing monomers, nitrogen heterocycles such as N-vinylpyrrolidone, N-vinylcaprolactam, N-vinyloxazolidone, and N-vinylimidazole. Homopolymers or copolymers containing the compound as a repeating unit are included. As the comonomer forming the copolymer, for example, one or more of common vinyl compounds such as styrene, (meth)acrylic acid ester, vinyl acetate and acrylamide can be selected and used.

In this case, the ratio of the anionic polymer to the cationic polymer used is preferably 3 to 10 parts by weight of the anionic polymer to 1 part of the anionic polymer in order to make the charge on the particle surface cationic. .

As commercial products of such composite organic particles, “PP-15” and “PP-17” (both manufactured by Meisei Chemical Industry Co., Ltd.) can be preferably used.

In addition, the amount of the water-dispersible resin in the surface treatment liquid (when using large particles and small particles, the total solid content of both) is 2% by weight or more from the viewpoint of ink fixability on the substrate surface when treated. , more preferably 3% by weight or more, and even more preferably 5% by weight or more. On the other hand, when the viscosity of the treatment liquid is too high, uniform treatment becomes difficult, so the resin content is preferably 50% by weight or less, more preferably 30% by weight or less.

The water contained in the surface treatment liquid functions as a solvent for the surface treatment liquid, that is, as a vehicle, and tap water, ion-exchanged water, deionized water, or the like can be used. Water is a highly volatile solvent and evaporates easily after being ejected onto the base material, so it prevents the voids in the base material after surface treatment from being clogged and reduces the hygroscopicity of wood after surface treatment. It has the effect of preventing deterioration of the original properties of the base material. Also, since water is harmless and highly safe, and has no problems such as VOCs, the surface-treated substrate can be made environmentally friendly.

The higher the water content in the surface treatment liquid, the lower the viscosity of the surface treatment liquid and the easier it is to handle. is more preferable.

The upper limit of the water content is not particularly limited, but in an embodiment in which the treatment liquid contains large particles and small particles of the water-dispersible resin, the water content is preferably 95% by weight or less. , 90% by weight or less. In another embodiment, the water content is preferably between 85% and 95% by weight.

The solvent of the surface treatment liquid is preferably composed mostly of water, but may contain a water-soluble organic solvent in addition to water, if necessary. As the water-soluble organic solvent, an organic compound that is liquid at room temperature and can be dissolved in water can be used, and it is preferable to use a water-soluble organic solvent that is uniformly mixed with the same volume of water at 1 atm and 20°C. .

For example, lower alcohols such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, 2-methyl-2-propanol; ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols such as glycol, propylene glycol, dipropylene glycol, tripropylene glycol and polypropylene glycol; glycerins such as glycerin, diglycerin, triglycerin and polyglycerin; acetins such as monoacetin, diacetin and triacetin; ethylene glycol monomethyl ether, Ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene Glycol ethers such as glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether; triethanolamine, 1-methyl-2- Pyrrolidone, 1,3-dimethyl-2-imidazolidinone, β-thiodiglycol, sulfolane and the like can be used. The boiling point of the water-soluble organic solvent is preferably 100°C or higher, more preferably 150°C or higher.

These water-soluble organic solvents may be used alone, or two or more of them may be used in combination as long as they form a single phase with water. The content of the water-soluble organic solvent is preferably 30% by weight or less in the treatment liquid (or 50% by weight or less in the solvent) from the viewpoint of viscosity adjustment and moisturizing effect.

In addition, the surface treatment liquid should reduce the surface tension so that it can be applied evenly to the surface of the noncombustible wood. In order to suppress aggregation and improve the storage stability of the liquid, it is preferable to further contain a surface tension adjuster (surfactant).

Surfactants are broadly classified into those with ionic (cationic, anionic, zwitterionic) hydrophilic parts and those with nonionic (nonionic) hydrophilic parts. From this point of view, it is preferable to use a nonionic surfactant that does not easily foam. In addition, although either low-molecular-weight or high-molecular-weight surfactants (generally refers to those having a molecular weight of about 2,000 or more) may be used, it is preferable to use high-molecular-weight surfactants. A surfactant with an HLB value of about 5 to 20 is preferable.

Examples of nonionic surfactants include ester-type surfactants such as glycerin fatty acid esters and fatty acid sorbitan esters, and ether-type surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers and polyoxypropylene alkyl ethers. and ether ester type such as polyoxyethylene sorbitan fatty acid ester.

In this embodiment, an acetylene glycol-based surfactant and a silicone-based surfactant can be preferably used.

Commercially available acetylene glycol-based surfactants include Surfynol 104E and 104H, which are acetylene glycols, Surfynol 420, 440, 465, 485, etc. (Air Products and Chemicals) having a structure in which ethylene oxide is added to acetylene glycol, and acetylene. Glycol Olphine E-1004, E-1010, E-1020, PD-002W, PD-004, EXP. 4001, EXP-4200, EXP-4123, EXP-4300, etc. (Nissin Chemical Industry Co., Ltd.), acetylenol E00, E00P of acetylene glycol, acetylenol E40, E100, etc. with ethylene oxide added to acetylene glycol (Kawaken Fine Chemicals Co., Ltd.).

Silicone-based surfactants have extremely high surface tension and contact angle reduction capabilities, so even if the surface of noncombustible wood is not hydrophilic, the surface treatment liquid can be rapidly diffused on the surface. As a result, the functional component of the surface treatment liquid can be uniformly fixed on the surface of the noncombustible wood, so that the ink can be uniformly fixed on the treated part when printing, and a high-quality printed image with high color development can be obtained. can be done.

Among silicone-based surfactants, polyether-modified silicone-based surfactants, alkyl/aralkyl-co-modified silicone-based surfactants, and acrylic silicone-based surfactants are preferred. Among commercially available products, "Silface SAG Series" (Nissin Chemical Industry Co., Ltd.) can be preferably used.

As the surfactant, any one of the above silicone-based surfactants and the like may be used alone, or a plurality of surfactants having good compatibility with each other may be used in combination.

When a surfactant is used, the content in the surface treatment liquid is preferably about 0.1% by weight or more, more preferably 0.3% by weight or more, and more preferably 0.5% by weight or more. On the other hand, the amount of the surfactant is preferably about 5% by weight or less, more preferably 4% by weight or less, and even more preferably 3% by weight or less.

In addition to the above components, known additives such as moisturizing agents, antifoaming agents, pH adjusters, antioxidants, preservatives, and the like are arbitrarily added to the surface treatment liquid as long as they do not inhibit the function of the treatment liquid. can. You may use these additives in combination of multiple types.

The surface treatment liquid consists of water, a cationic water-dispersible resin, a surface tension modifier, and optional additives, if any, in a known dispersing machine such as a bead mill. Alternatively, it can be prepared by dividing and adding, dispersing, and optionally passing through a known filter such as a membrane filter.

Moreover, when the surface treatment liquid contains large particles and small particles as the cationic water-dispersible resin, the surface treatment liquid can be applied in two steps. That is, for example, a surface treatment liquid containing either large particles or small particles and a surface treatment liquid containing the other one may be prepared and applied to noncombustible wood. When applying large particles and small particles separately, if the small particles are applied first, the penetration of the noncombustible wood into the voids will proceed and the effect as a binder for the ink may decrease, so the large particles should be applied first. It is preferable to apply to When two types of surface treatment liquids are applied as described above, the amount of the surface treatment liquid is the total amount of the two types of surface treatment liquids.

The following notes are further disclosed with respect to the present invention.
(Appendix)

In the liquid coating apparatus of the present invention, the coating section can apply the liquid to the surface of the coating medium by contacting the coating medium, and the pressure with which the sliding section presses the surface of the coating medium is It can be higher than the pressure pressing against the surface of the coating medium.

The liquid applying apparatus of the present invention can include a cleaning section that cleans the sliding section.

In the liquid applying device of the present invention, the cleaning section can clean the sliding section while recovering the liquid absorbed by the sliding section.

In the liquid applying apparatus of the present invention, the sliding section can have a roller that absorbs part of the liquid applied to the application medium, and the cleaning section removes the liquid absorbed by the roller by rotating the roller. can be recovered.

1 liquid coating device 2 shuttle base unit 3 flat bed unit 3a medium placement surface 4 shuttle unit 6 pretreatment unit 10 coating roller 11 sponge roller 11a sponge roller main body 11b support member 11c spring portion 12 cleaning portion 12a recovery roller 12b liquid receiving portion 12c Spatula 15 Print control device 20 Inkjet printer 31 Mounting unit 32 Sub-scanning drive motor 41 Housing 42 Main scanning drive guide 43 Main scanning drive motor 44 Head elevation guide 45 Head elevation motor 46 Head unit 51 Inkjet head 53 Ink supply pipe 33A, 33B sub-scanning drive guide L liquid M application medium

Claims (5)

an application unit that applies a liquid to the surface of the application medium;
While contacting the surface of the application medium coated with the liquid by the application section with a predetermined pressure, the liquid is moved relative to the application medium to slide on the surface of the application medium, and the liquid is applied by the application section. and a sliding portion that absorbs part of the liquid applied to the application medium. The application unit is in contact with the application medium and applies the liquid to the surface of the application medium,
2. The liquid coating apparatus according to claim 1, wherein the pressure with which the sliding portion presses the surface of the coating medium is higher than the pressure with which the coating portion presses the surface of the coating medium. 3. The liquid applying device according to claim 1, further comprising a cleaning section for cleaning said sliding section. 4. The liquid applying device according to claim 3, wherein the cleaning section cleans the sliding section while recovering the liquid absorbed by the sliding section. The sliding portion has a roller that absorbs part of the liquid applied to the application medium,
5. The liquid applying apparatus according to claim 4, wherein the cleaning section collects the liquid absorbed by the roller as the roller rotates.

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