JP2002038399A - Method for coating film on pulp molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for coating film on pulp moldings which can efficiently form uniform film of a desired performance on the surface of pulp moldings. SOLUTION: When a film layer is formed on the surface of the pulp molding, the pulp molding 1 are continuously allowed to rotate around a prescribed axis C at least from after the surface is coated with a paint until the undried coating film formed on the surface of the pulp molding 1 becomes tack-free.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulp molded article, and more particularly to a method for forming a coating film on a pulp molded container and a pulp molded container.

[0002]

2. Description of the Related Art
Background of the Invention Due to environmental problems, pulp molded products have attracted attention. Since the pulp molded article is formed mainly of pulp fibers, as it is, various properties such as sufficient waterproofness, moisture proofness and strength cannot be obtained as compared with the plastic molded article. For this reason, it is usually necessary to form a coating film on the surface of a pulp molded article and to add desired performance according to its use.

However, pulp molded products are
Unlike plastic containers, the surface is easily impregnated with paint, and when moldings have corners, such as when the moldings have corners, the surface is not sufficiently smooth, particularly at the corners, and fluffing occurs. In some cases, desired performance cannot be obtained unless the coating amount of the paint is increased. As a solution to such a problem, it is conceivable to repeatedly apply the paint until the desired performance is obtained.However, since the number of manufacturing steps is increased, the manufacturing efficiency has to be reduced, and the cost is also an advantage. Absent. Also, in the conventional method,
If a thick coating film is formed by one coating, the coating will sag after the application, and the above-mentioned various properties will be non-uniform after drying.

Accordingly, the present invention provides a method for forming a coating film of a pulp molded article and a pulp molded container capable of efficiently forming a coating film having desired properties uniformly on the surface of the pulp molded article. It is in.

[0005]

The present invention provides a method for forming a coating film on the surface of a pulp molded article, comprising:
A pulp molded article characterized by continuing to rotate the pulp molded article around a predetermined axis until the wet coating film formed on the surface of the pulp molded article becomes tack-free after application of the paint. The above object has been attained by providing a method for forming a coating film.

The present invention also relates to a pulp molded container formed with a coating by the method for forming a coating of a pulp molded product of the present invention, wherein a corner is provided around a trunk or between the trunk and a bottom. The present invention provides a pulp molding container having a portion, wherein a coating amount of paint per unit area of the corner surface is larger than a coating amount of paint per unit area of the body surface.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on preferred embodiments with reference to the drawings.

[0008] The method for forming a coating film on a pulp molded article according to the present invention comprises, when forming a coating film on the surface of the pulp molded article, at least forming an undried film formed on the surface of the pulp molded article after coating with a coating material. Until the coating film becomes tack-free, the pulp molded article is continuously rotated about a predetermined axis.

In the present invention, the paint for forming the coating film is selected depending on the performance to be imparted to the surface (inner surface or outer surface) of the molded article. For example, when imparting waterproof and moisture-proof properties to the surface of a pulp molded article, acrylic resin, styrene resin, urethane resin, melamine resin, olefin resin, epoxy resin, polyvinyl alcohol resin, chloride Examples thereof include an aqueous emulsion paint containing a resin such as a vinylidene-based resin in a solid content, or an aqueous paint or an organic solvent-based paint of these resins.

[0010] In the present specification, a period from after the coating of the coating material until the wet coating film formed on the surface of the pulp molded article becomes tack-free is a state in which the rotation of the molded article is stopped, It refers to a state in which sagging and film thickness unevenness do not occur due to the flow of the coating film.Specifically, even if the coating film is touched with a finger or a finger wearing gloves made of powder-free tex or the like, It can be determined that the tack-free state has been reached when no trace is left. Confirmation of tack-free is performed immediately after the rotation of the molded body is stopped. The time required to become tack-free immediately after the coating of the paint (tack-free time) is determined by the type of paint, the conditions for forming the coating film (temperature, humidity, etc.), or the molded product immediately before being applied to the pulp molded product Depends on the water content and the like. For example, when a water-based emulsion type paint containing an acrylic resin as a solid component is applied to the surface of a pulp molded article having a water content of 4% and dried at about 100 ° C., the tack-free time is 30 to 150 seconds. It is common.

As a method of forming the undried coating film, there are a method of forming by spraying the coating and a method of immersing the pulp molded article in a tank filled with the coating. In addition, when the pulp molded article is a container, a method of injecting the coating material into the container and then discharging the coating material to form the container may be used.

[0012] The thickness of the coating material for forming an undried coating film is such that the waterproof, moisture-proof and gas barrier properties are sufficiently imparted, or a thick film is used for uniform waterproof, moisture-proof and gas barrier properties. 20 to 3 in forming a coating film having various performances
It is preferably 00 μm, more preferably 40 to 200 μm.

The coating amount of the paint for forming the undried coating film is determined so as to sufficiently impart waterproofness, moistureproofness, and gas barrier properties, or a thick film having uniform waterproofness, moistureproofness, and gas barrier properties. 20 to 3 in forming a coating film having various performances
00 g / m ² , preferably 40 to 200 g / m ^2.
m ² is more preferable.

In the present invention, when the pulp molded article on which the undried coating film is formed is rotated around a predetermined axis, the predetermined axis refers to an axis passing through the center of gravity of the molded article. Further, in the present invention, the pulp molded article can be continuously rotated around two axes including another axis having a predetermined angle with respect to the predetermined axis. The maximum rotational speed around the predetermined axis is preferably from 7 to 1300 m / min, more preferably from 15 to 80 m / min, from the viewpoint of preventing dripping of the paint and uniforming the above-mentioned various performances. preferable. Further, the rotation speed can be made constant or intermittent depending on the form of the container for forming the coating film.

When the pulp molded product is a container having a corner and a flat portion, the molding is rotated at a predetermined angle as described above, so that the coating per unit area of the surface of the corner is obtained. It is preferable that the work amount is larger than the coating amount per unit area of the flat portion surface. For example, as shown in FIG. 3, when an undried coating film is formed on the surface of a container having a corner portion in the body, the number of rotations is appropriately adjusted using centrifugal force caused by rotation of the molded body. By doing
The coating amount per unit area on the corner portion surface can be made larger than the coating amount on the flat portion surface.

[0016] Until the undried coating film formed on the surface of the pulp molded product as described above becomes tack-free, the pulp molded product is continuously rotated about a predetermined axis, and then the coating film is dried. . The method of drying the coating film,
Although it can be appropriately selected according to the coating material for forming the coating film, a method of blowing and drying an air current such as heated air on the coating film, infrared rays, far infrared rays, microwave,
A method of irradiating with ultraviolet rays, an electron beam or the like and drying may be used. Among them, a method of blowing an air current such as an infrared ray or a heated air, and a method of irradiating an infrared ray, a far infrared ray or the like are preferably used in view of the scale of the production equipment and the handling property. The drying time can be appropriately set depending on the composition of the coating film, the thickness of the coating film, and the drying method.

Further, in the present invention, since the coating film can be dried evenly and various properties such as waterproofness, moistureproofness and gas barrier properties can be made more uniform, the wet pulp formed on the surface of the pulp molded article can be made uniform. Until the coating becomes tack-free
After continuing to rotate the pulp molded body around the predetermined axis, it is preferable to rotate the pulp molded body around the predetermined axis also in the step of drying the coating film.

The pulp molded article used in the method for forming a coating film of the pulp molded article of the present invention includes, for example,
Using a slurry of paper fibers as a raw material, assembling a set of split dies to form a cavity, and while the cavity inner surface is covered with a predetermined paper making net, while pressing the slurry at a predetermined pressure into the cavity, A liquid component in the slurry is suctioned from the outside of the papermaking mold under a negative pressure to form a paper fiber laminate on the inner surface of the cavity, an elastic core is inserted into the paper fiber laminate, and compressed air is supplied into the core. The core is swelled and the paper fiber laminate is depressed and dewatered by pressing the paper fiber laminate therefrom at a predetermined pressure, and the paper fiber laminate after dehydration is transferred to another drying mold and loaded into the drying mold, An elastic core is inserted into the inside of the paper fiber laminate, and the paper fiber laminate is pressed by the core from the inside with a predetermined pressure, and the paper fiber laminate is heated by the drying type heating means. It is preferable to use one produced by drying.
The form of the pulp molded article used in the method for forming a coating film of the pulp molded article of the present invention is not particularly limited, and examples thereof include a bottomed cylindrical bottle container, the same cup container, and a cylindrical body. Can be When the horizontal cross-sectional shape of the body of the molded body is elliptical, corners located at both ends of the long axis with large curvature are corners.

The pulp molded container of the present invention will be described. The pulp molded container of the present invention is a container on which a coating film is formed by the method for forming a coating film of the pulp molded article of the present invention described above. The pulp molded container of the present invention has a corner around the trunk or between the trunk and the bottom, and the coating amount of the paint per unit area of the surface of the corner is flat. It is more than the amount of paint applied per unit area of the surface of the part.

Further, in the pulp mold container of the present invention, the pulp mold container is dried so that various properties such as waterproofness, moisture proofness, gas barrier properties and the like including the corners become uniform throughout the molded body. The thickness of the coating on the corner surface / (the thickness of the coating on the body surface) is preferably from 1.05 to 1.5, and more preferably from 1.1 to 2.0.

Next, an embodiment of the method for forming a coating film on a pulp molded article of the present invention will be described. 1 and 2 are schematic views showing one embodiment of the method for forming a coating film on the pulp molded article of the present invention described above. The present embodiment is a pulp mold container having a hollow bottle shape (hereinafter, referred to as a pulp mold container).
It is called a bottle container at the end. 1) forming a coating film on the inner surface and the outer surface of 1);

As shown in FIG. 1 (a), when a coating film is to be formed on the inner surface of the container, the bottle container 1 is horizontally and centered by a predetermined holding means (not shown) on the bottom side thereof. The nozzle head 20 of the spray device 2 is inserted through the opening 10 of the bottle container 1 while being supported rotatably around the axis C.

Next, as shown in FIG. 3B, the bottle container 1 is rotated at a predetermined rotation speed around the central axis C by the gripping means. Then, the nozzle head 20 inserted into the bottle container 1 is moved in the horizontal direction to apply the paint from the body to the mouth and neck of the bottle container 1. In the application process using the spray, the bottle container 1 and the nozzle head 20 may be relatively rotated, and the bottle container 1 may be fixed and the nozzle head 20 may be rotated.

Subsequently, as shown in FIG. 2C, a paint is applied to the bottom of the bottle container 1 while the nozzle head 20 is positioned at a predetermined position while rotating the bottle container 1 at a predetermined rotation speed. I do. Then, the rotation of the bottle container 1 is continued until the undried coating film formed on the surface becomes tack-free. The spray container 2 can use air spray, airless spray, electrostatic spray, or the like. Further, the discharge direction and the discharge width of the nozzle head 20 with respect to the container can be appropriately selected depending on the shape of the molded body such as the bottle container 1 or the like. For example, the corners of the container can be applied using a nozzle head having a narrow discharge width, or the inner surface of the container can be applied at once over a wide area using a nozzle head having a wide discharge width and capable of radial discharge.

Next, as shown in FIG. 3D, the bottle container 1 is moved from the painting booth S to the drying booth D, and the bottle container 1 is moved horizontally and the center axis C in the drying booth D in the same manner as described above. It is rotated around at a predetermined rotation speed. Then, as shown in the figure, a nozzle 3 for blowing hot air at a predetermined temperature in a curtain shape is inserted into the bottle container 1, and the undried coating film formed on the inner surface of the bottle container 1 is dried.

As shown in FIG. 2A, when forming a coating film on the outer surface of the container, the bottle container 1 is moved to a drying booth S 'for coating the outer surface. In this case, the bottle container 1 is fixed by inserting a gripping means (not shown) from the opening thereof, and the container is supported horizontally and rotatably around its central axis C. Further, an extra grip portion may be formed on the container opening side (the grip portion will be deleted in a later step), and the grip portion may be gripped by gripping means. And the bottle container 1
Is rotated horizontally at a predetermined rotation speed around its central axis. Then, at a predetermined position above the bottle container 1,
The nozzle head 20 is moved horizontally to apply a predetermined amount of paint to the outer surface of the bottle container 1 from the mouth and neck to the trunk.

Next, as shown in FIG. 2B, the bottle container 1 is continuously rotated at a predetermined rotation speed, and at a position away from the bottom of the bottle container 1 by a predetermined position, the bottle container 1 is A predetermined amount of a coating material is applied to the outer surface of the bottom portion of the first coating material. Then, the rotation of the bottle container 1 is continued until the undried coating film formed on the surface becomes tack-free.

Next, as shown in FIG. 2C, the bottle container 1 is moved from the painting booth S to the drying booth D, and the bottle container 1 is moved horizontally and the center axis C in the drying booth D in the same manner as described above. It is rotated around at a predetermined rotation speed. When the bottle container is moved from the coating booth S to the drying booth D, the rotation is preferably continued. Then, as shown in the figure, at a predetermined position above the bottle container 1, hot air of a predetermined temperature is blown from a nozzle for blowing hot air in a curtain shape for a predetermined time,
The undried coating film formed on the outer surface of the bottle container 1 is dried.

As described above, according to the method for forming a coating film of a pulp molded article of the present embodiment, it is possible to efficiently form a coating film having a desired performance uniformly on the inner surface and the outer surface of a bottle container. Can be. Further, the bottle container thus obtained has a desired performance uniformly on its inner surface or outer surface.

FIG. 3 shows an embodiment of the pulp molded container of the present invention formed by the method for forming a coating film of the pulp molded product of the present invention described above. In the figure, reference numeral 1 'indicates a pulp molded container.

This pulp molded container 1 'is a container having a corner portion 1a' and a flat portion 1b 'in the body, and sprays paint while rotating the container 1' with its central axis horizontal. By forming an undried coating film on the inner surface of the container 1 'and continuing to rotate the undried coating film formed on the inner surface of the container until the coating film becomes tack-free, the thickness of the coating film on the corner 1a' Is made thicker than the flat portion 1b '.

As shown in FIG. 2B, in the pulp molding container 1, the thickness of the coating on the inner surface of the corner 1a 'is larger than the thickness of the coating on the inner surface of the flat portion 1b'. It is formed thick, and by doing so, the desired performance can be obtained uniformly at the corners and flat portions.

The present invention is not limited to the above embodiment, and can be appropriately modified without departing from the gist of the present invention.

For example, as shown in FIG. 4, an undried coating film may be formed on the inner surface of the pulp molded article (container) 11. As shown in FIG. 2A, in a state where the opening of the container 11 is directed upward and its central axis C is inclined by a predetermined angle from the vertical axis, the container 11 is held by the gripping means (not shown). The container 11 is rotatably supported around, and the paint filling nozzle 4 is inserted from the opening of the container 11, and the container 11 is rotated at a predetermined rotation speed around the central axis, and the paint is injected into the container from the filling nozzle 4. I do. Then, after the filling nozzle 4 is retracted from the inside of the container 11 as shown in FIG. 6B, the container 11 is rotated around the horizontal axis in the vertical plane while continuing to rotate as shown in FIG. The container 11 is turned around, and in this state, the container 11 is discharged around the central axis C and formed.

For example, as shown in FIG. 5, an undried coating film can be formed on the outer surface of the pulp molded article (container) 11 '. As shown in FIG. 1A, the container 11 'is gripped on its opening side by a gripping means (not shown), and is immersed in a tank P filled with paint for a predetermined time.
Then, the container 11 'is pulled up from the tank P, and FIG.
As shown in (5), excess paint adhering to the outer surface is removed while rotating the container 11 'around its central axis C at a predetermined angle from the vertical axis. By forming the coating film in this manner, the corner 1 between the trunk and the bottom of the outer surface of the container 11 is formed.
The film thickness of the coating film in 1a 'can be made thicker than the body portion (other portions), and the performance can be made uniform with the body portion. In addition, instead of applying the paint by dipping the container in the tank P, the paint can be applied by showering the paint discharged from the shower nozzle toward the outer surface of the container.

[0036]

According to the method for forming a coating film of a pulp molded article of the present invention, a coating film having desired performance can be efficiently formed on the surface of the pulp molded article. Further, the pulp molded container of the present invention has a desired performance evenly on its surface.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a step of forming a wet coating film on the inner surface of a container in the method for forming a coating film on the surface of a pulp molded article of the present invention. The figure which shows the state before inserting in a shaping | molding container, (b) is the figure which shows the state in which a nozzle head is inserted and the paint is sprayed on the inner peripheral surface of a container, (c) is the state which inserts a nozzle head. It is a figure which shows the state which is spraying paint on the bottom inner surface of a container, and (d) is a figure which shows the state which dried a coating film.

FIG. 2 is a schematic view showing a step of forming a wet coating film on the outer surface of a container in the method for forming a coating film on the surface of a pulp molded article according to the present invention; The figure which shows the state before inserting in a shaping | molding container, (b) shows the state which sprays paint on the outer peripheral surface of a container by inserting a nozzle head, (c) shows the container by inserting a nozzle head. FIG. 3D is a diagram showing a state where a paint is sprayed on the outer surface of the bottom surface of FIG.

FIGS. 3A and 3B are schematic diagrams showing one embodiment of a pulp molded container in which a coating film is formed by the method for forming a coating film of a pulp molded product of the present invention, wherein FIG. 3A is a perspective view and FIG. FIG.

FIG. 4 is a schematic view showing a procedure for forming a wet coating film in the method for forming a coating film of a pulp molded article of the present invention;
(A) is a diagram showing a paint injection state by a filling nozzle,
(B) is a diagram showing a state where the filling nozzle is retracted from the container, and (c) is a diagram showing a state where the paint is discharged from the container.

FIG. 5 is a schematic view showing a procedure for forming a wet coating film in the method for forming a coating film of a pulp molded article of the present invention;
(A) is a figure which shows the state in which the container is immersed in the tank filled with paint, and (b) is a figure which shows the state in which excess paint is removed.

[Explanation of symbols]

 1, 1 ', 11, 11' Pulp molded container 1a Corner 1b Body flat

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) B05D 7/22 B05D 7/22 Q 4L055 B65D 1/09 B65D 8/04 Z 8/04 23/02 Z 23/02 23 / 08 B 23/08 1/00 C (72) Inventor Shingo Odashima 2606 Akabane, Kaiga-cho, Haga-gun, Tochigi Pref. JA08 JB23 JB30 JC02 JD01 JD02 4D075 AA01 AA68 AA82 AB01 DA19 DA20 DB18 DC44 4F040 AA15 CC00 4L055 BF09 FA11 FA19 GA05 GA50

Claims (9)

[Claims] When forming a coating film on the surface of a pulp molded article, at least until the wet coating film formed on the surface of the pulp molded article becomes tack-free after application of the coating material. A method for forming a coating film on a pulp molded article, comprising continuously rotating the pulp molded article around a predetermined axis. 2. The method according to claim 1, wherein the undried coating film is formed by spraying the coating material. 3. The coating film formation of the pulp molded article according to claim 1, wherein the undried coating film is formed by immersing the pulp molded article in a tank filled with the paint and then pulling up from the tank. Method. 4. The method for forming a coating film on a pulp molded article according to claim 1, wherein the pulp molded article is a cylindrical container having a bottom, and the surface is an outer surface and / or an inner surface of the container. 5. The pulp molded article according to claim 1, wherein the pulp molded article is a container, and the undried coating film is formed by injecting a paint into the container and discharging the paint. Method. 6. The method for forming a coating film on a pulp molded article according to claim 1, wherein the thickness of the coating material for forming the wet coating film is 20 to 300 μm. 7. The pulp molded article is a container having a corner portion and a flat portion, and the coating amount per unit area of the corner portion surface is larger than the coating amount per unit area of the flat portion surface. The method for forming a coating film on a pulp molded article according to claim 1. 8. A pulp molded container having a coating formed by the method for forming a coating of a pulp molded article according to claim 1, wherein the container has a corner around the trunk or between the trunk and the bottom. And a pulp molding container in which the amount of paint applied per unit area on the corner surface is larger than the amount of paint applied per unit area on the body surface. 9. (Thickness of a coating film on the surface of the corner portion) /
(The thickness of the coating film on the body surface) is 1.05 to 2.
The pulp molded container according to claim 8, which is 0.