JP2001055697A - Production of molded pulp product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a molded pulp product having excellent appearance and without forming a steam-passing trace on the surface of the product. SOLUTION: A dehydrated molded pulp product 7 is heated with a hot mold 10 and a core 18 is expanded by introducing a fluid into the core while keeping the pulp product in hot state. The molded product 7 is pressed against the inner surface of the hot mold 10 with the expanded core 18 to effect the hot drying of the molded product 7. The core 18 has an outer layer 18a and an inner layer 18b, the inner layer 18b is essentially impermeable to the fluid and the outer layer 18a forms an exhaustion channel between the molded product 7 and the inner layer 18b when the molded product 7 is pressed with the expanded core 18. Steam generated by heating is exhausted from the hot mold 10 through the exhaustion channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a pulp molded article.

[0002]

2. Description of the Related Art A drying mold used for drying a wet molded article formed by a pulp molding method has a ventilation passage for discharging steam out of the mold. Have been. Various types are known as a drying type having such an air passage. For example, (1) a mold with a through hole in the inner surface of the mold, (2) a mold with a through hole and the inner surface covered with a net, (3) a mold with punch metal, (4) a plastic mold And the like, in which a vent used for the mold is disposed on the inner surface of the mold.

However, in the case of the dry mold of (1), traces of the through holes are transferred to the surface of the molded article in a convex shape, and the appearance of the molded article is impaired. In addition, it is difficult to form a through hole in a shallow angle portion such as the vicinity of a dividing plane (PL: parting line). In the dry mold of (2), traces of the net are transferred to the surface of the molded body, and the molded body may be damaged when the mold is released, depending on the shape of the molded body. In the molded article (3), traces of holes are transferred to the surface of the molded article in a convex shape, and it is difficult to manufacture a mold having a complicated shape. The dry mold of (4) has less noticeable marks such as holes than the dry molds of (1) to (3), but it takes time to attach the vent, and the parts with small curvature and screw parts etc. It is difficult to attach a vent to the car. Furthermore, pulp fibers adhere and accumulate around the vent,
Clogging may occur.

Accordingly, an object of the present invention is to provide a method for producing a molded pulp molded article which can prevent formation of traces of a water vapor passage on the surface of the molded article and exhibit a good appearance.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a pulp molded article formed by papermaking and dewatered to a predetermined moisture content while being heated to a predetermined temperature by a heating mold, thereby forming a hollow scalable hollow pulp mold. A predetermined fluid is supplied into the core to expand the core, and the expanded core presses the molded body toward the inner surface of the heating die to heat and dry the molded body. The manufacturing method, wherein the core has an outer layer that comes into contact with the molded body when the core is expanded, and an inner layer that is located inside the outer layer, and the inner layer substantially removes the fluid. The outer layer is formed such that when the outer layer presses the molded body by the expanded core, between the molded body and the inner layer, a vapor generated by heating is exhausted to the outside of the heating mold. To form a path It is obtained by achieving the above object by providing a method for producing a pulp molded article using the child.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. The present embodiment is an example of manufacturing a bottle-shaped pulp molded article (hereinafter, also simply referred to as a molded article) having an open mouth and neck and a trunk having a diameter larger than that of the mouth and neck. FIG. 1 shows the paper making and dewatering steps in this embodiment sequentially.
(A) is a pulp slurry injection and suction dewatering step, (b)
Is a core insertion step, (c) is a pressure dehydration step, and (d) is a step of opening a papermaking mold.

In the present embodiment, a pulp slurry is supplied into the cavity of a papermaking mold which is formed of a set of mold dies, and a cavity of a predetermined shape is formed by combining the mold dies. After forming a wet molded body in a wet state, a hollow core having air permeability and expandable and contractable is inserted into the wet molded body, and then a predetermined fluid is supplied into the core. The core is expanded, and the undried molded body is pressed against the inner surface of the cavity by the expanded core to dehydrate.

More specifically, first, as shown in FIG. 1A, a papermaking mold 1 comprising two split molds 2 and 3 and having a cavity 4 of a predetermined shape formed by combining the split molds. Prepare The cavity 4 communicates with the outside of the papermaking mold 1 through a slurry injection port 5 opened to the outside. The inner surface of the cavity 4 is covered with a papermaking net (not shown) having a mesh of a predetermined size. Each of the split dies 2 and 3 is formed with a plurality of communication passages 6 communicating from the inside (ie, the inner surface of the cavity 4) to the outside. Each communication path 6 is connected to suction means (not shown) such as a suction pump.

In this state, a predetermined amount of pulp slurry is injected into the cavity 4 through the slurry injection port 5.
At the same time, the inside of the cavity 4 is
The pulp fibers are deposited on the papermaking surface, that is, on the papermaking net covering the inner surface of the cavity 4, by suctioning the water under reduced pressure toward the outside of the pulp slurry. As a result, on the papermaking net, a wet molded body 7 formed by depositing pulp fibers is formed.

The formed compact 7 is subjected to a pressure dehydration step. First, as shown in FIG. 1 (b), a scalable hollow core 8 is inserted into a molded body 7 in a contracted state while the papermaking mold 1 is sucked from the inside to the outside. I do. In the present invention, the expansion and contraction means that the volume of the core 8 changes due to expansion and contraction, and that the core 8 itself does not expand and contract, but the fluid is supplied to or removed from the interior to reduce the volume. Is changed. Examples of the former include a core made of an elastic material such as urethane, fluorine-based rubber, silicone-based rubber or elastomer, and examples of the latter include plastic materials such as polyethylene and polypropylene, and films of these plastic materials. Examples include a film on which aluminum or silica is deposited, a film in which an aluminum foil is laminated on a film of such a plastic material, and a core made of a flexible material such as paper or cloth. In the present embodiment, a bag-shaped (balloon-shaped) core made of a stretchable elastic material is used as the core 8.

Next, as shown in FIG. 1C, a predetermined fluid is supplied into the core 8 to expand the core 8, and the molded body 7 in a wet state is expanded by the expanded core 8. That is, it is pressed toward the inner surface of the cavity 4. As a result, the pressurized dehydration of the molded body 7 proceeds, and the inner surface shape of the cavity 4 is transferred to the molded body 7. Further, since the molded body 7 is pressed from the inside toward the inner surface of the cavity 4, even if the shape of the cavity 4 is complicated, the molded body 7 is accurately transferred to the molded body 10 on the inner surface of the cavity 4. . Further, it is possible to easily manufacture a deep-bottom molded body whose side wall rises almost vertically. As the fluid used to expand the core 8, for example, air (pressurized air), hot air (heated pressurized air), superheated steam, oil (heated oil), and other various liquids are used. In particular, it is preferable to use air, hot air, or superheated steam from the viewpoint of operability and the like. The pressure for supplying the fluid is preferably 0.01 to 5 MPa, particularly preferably 0.1 to 3 MPa.

When the molded body 7 can be dehydrated to a predetermined moisture content and the shape of the inner surface of the cavity 4 is sufficiently transferred to the molded body 7, the fluid in the core 8 is drained as shown in FIG. The core 8 is reduced. Next, the reduced core 8 is taken out of the molded body 7, and the papermaking mold 1 is further opened to take out the wet molded body 7 having a predetermined moisture content.

The molded body 7 taken out is then subjected to a heating and drying step. A heating mold 10 shown in FIG. 2 is used for heating and drying the molded body 7. The heating mold 10 includes a set of split molds 12,1.
3, and a cavity 14 having a predetermined shape is formed by combining the split dies. In the present embodiment, the cavity shape of the heating die 10 and the papermaking die 1
The cavity shape is the same. Heating mold 10
, Ie, the inner surface of the cavity 14, is not formed with a ventilation path for exhausting water vapor generated by heating the molded body 7 in a wet state. This is significantly different from the fact that the communication path 6 (see FIG. 1) is formed in the papermaking mold 1. Although not shown, each split mold 12 and 13 is provided with a predetermined heating means.

A hollow core 18 having a hollow shape that can be expanded and contracted is inserted into the cavity 14 of the heating mold 10. The core 18 has a shape substantially similar to the shape of the cavity 14 and is slightly smaller than the cavity 14. The core 18 expands when a predetermined fluid is supplied thereto, and the molded body 7 loaded in the cavity 14 is formed.
Is pressed toward the inner surface of the cavity 14. Here, the meaning of the expansion and contraction is the same as the meaning of the expansion and contraction described for the core 8 used for pressurized dehydration of the molded body 7.

The core 18 has an outer layer 18a which comes into contact with the molded body 7 when expanded, and an inner layer 1 located inside the outer layer 18a.
8b. The inner layer 18b is substantially impermeable to the fluid used to expand the core 18.
"Substantially" does not mean that the inner layer 18b does not allow the fluid to permeate at all. When the fluid is supplied into the core 18 to expand the core 18, the expanded state is changed. This means that the fluid is not permeated to the extent that it is maintained. As the inner layer 18b, the same material as the core 8 used for pressurized dehydration of the molded body 7 can be used.
In the present embodiment, the inner layer 18b is made of an elastic and stretchable material.

The outer layer 18a forms an air passage between the molded body 7 and the inner layer 18b for exhausting steam generated by heating to the outside of the heating mold 10 when the molded body 7 is pressed by the expanded core 18. It has been made like that. The material constituting the outer layer 18a is not particularly limited as long as such an air passage is formed. As a material constituting the outer layer 18a, the core 1 can be formed in a free shape without being restricted by the uneven shape of the molded body.
It is preferable to use a knitted fabric, a woven fabric or a non-woven fabric from the viewpoint that 8 can be expanded and contracted, and it is particularly preferable to use a knitted fabric because it has sufficient elasticity. When the inner layer 18b is made of an elastic and stretchable material, the outer layer 18b
It is preferable that a is also made of a stretchable material.

From the viewpoint of sufficiently securing the air passage, the thickness of the outer layer 18a is set to 0.2 before the core 18 is expanded.
It is preferably from 3.0 to 3.0 mm, particularly preferably from 1.0 to 2.0 mm. In a state where the core 18 is expanded and presses the molded body 7, 0.2 to 2.5 mm, particularly 0.2 to 1.5 mm
mm.

The outer layer 18a and the inner layer 18b are integrally fixed by a predetermined fixing means. As a fixing means, a projection is provided on the inner layer 18b by an adhesive means using an adhesive,
Means for hooking the outer layer 18a and fixing the outer layer 18a can be mentioned. In particular, it is preferable to use an adhering means using an adhesive because the outer layer 18a can be fixed flat. When the outer layer 18a and the inner layer 18b are both expandable and contractible and the core 18 is expandable, the outer layer 18a and the inner layer 18b may be point-bonded with an adhesive.
This is preferred because it does not hinder the elasticity of the polymer.

In the upper part of the core 18, the outer layer 18a and the inner layer 18b are separated from each other, and both extend horizontally outward and have a flange-like shape. The extension 18a 'of the outer layer 18a is thicker than other portions of the outer layer 18a. This extension 1
The thickness of 8a 'is preferably 1 to 10 times, particularly 3 to 5 times the thickness of the other portion of the outer layer 18a, from the viewpoint that a sufficient air passage communicating with the outside can be ensured. Each of the extending portions 18a 'is sandwiched and fixed by a first fixing member 19 and a second fixing member 20 each having a circular center portion. An annular vent hole 21 communicating with the outside is formed between the first fixing member 19 and the second fixing member 20 in a state where the extension portion 18a 'of the outer layer 18a is clamped and fixed. . The vent hole 21 is formed in the outer layer 18.
a in communication with the extension 18a '. by this,
Water vapor generated by heating the molded body 7 is applied to the outer layer 18a.
The air is discharged to the outside through the vent hole 21 through the ventilation path formed in the above. In particular, as described above, since the extended portion 18a 'of the outer layer 18a is thicker than the other portions of the outer layer 18a, the ventilation path is sufficiently secured, and the water vapor is efficiently exhausted to the outside.

On the other hand, the extension 18b 'of the inner layer 18b is
In each case, a circular second fixing member 20 whose center is hollowed out
And the third fixing member 22. The first to third fixing members are fixed to each other by predetermined means. When the first to third fixing members are fixed, the hole 23 is formed at the center,
The hole 23 communicates with the core 18. Core 18
At the time of expansion, a predetermined fluid is supplied into the core 18 through the hole 23.

The step of heating and drying the molded body 7 using the core 18 and the heating mold 10 will be described with reference to FIG.
In FIG. 3, (a) is a core insertion step, (b) is a step of expanding the core and heating and drying the molded body, and (c) is a step of opening the heating die.

First, as shown in FIG. 3 (a), the compact 7 dehydrated to a predetermined moisture content by pressure dehydration shown in FIG. 1 is loaded into a heating mold 10 heated to a predetermined temperature.
Next, the core 18 is inserted into the molded body 7 loaded. At the time of insertion, the inside of the core 18 is vacuum-evacuated to reduce the volume to form an elongated shape, and a cross-sectional shape that passes through the opening of the molded body 7.

When the core 18 is inserted into the molded body 7, as shown in FIG. 3B, a fluid is supplied into the core 18 through the hole 23 to expand the core 18, and Child 18
Presses the molded body 7 toward the inner surface of the cavity 14 of the heating mold 10. The type and supply pressure of the fluid can be the same as in the pressure dehydration step. In this state, the molded body 7 is dried by heating. Water vapor generated by heating and drying the molded body 7 is exhausted to the outside through the ventilation path and the vent hole 21 formed by the outer layer 18 a of the core 18. Therefore, the drying of the molded body 7 is performed extremely smoothly, and the drying efficiency is improved. In addition, as described above, the heating mold 1
Since no air passage for exhausting water vapor is formed on the inner surface of No. 0 and the entire inner surface is smooth, the shape of the smooth surface is transferred to the molded body 7 by pressing the core 18. You. As a result, the surface of the finally obtained molded body 7 is extremely smooth, and exhibits a good appearance. In addition, in the conventional heating type having an air passage for exhausting water vapor formed on the inner surface, the disadvantage that the pulp fiber is clogged in the air passage does not occur in the production method of the present invention. Moreover, in the manufacturing method of the present invention, it is not necessary to provide the ventilation path, which is essential in the conventional heating mold, so that the heat transfer efficiency is improved, the drying efficiency is improved, and the manufacturing cost of the heating mold is reduced.

By using a heating fluid such as superheated steam as the fluid to be supplied to the core 18, the drying is performed more efficiently and the drying efficiency is further improved.

When the molded body 7 is sufficiently dried, the fluid in the core 18 is drained. Further, as shown in FIG.
The inside of the mold 8 is vacuum-evacuated to reduce the volume so as to have an elongated shape at the time of insertion, and is taken out of the molded body 7. Further, the heating die 10 is opened, and the pulp molded article 7 as an object is taken out.

The bottle-shaped pulp molded article manufactured in this manner has no joint at the mouth, neck, body and bottom, and the mouth, neck, body and bottom are integrally formed. In addition, in the heating and drying of the molded body, a heating mold in which no ventilation path is formed on the inner surface and the inner surface is a smooth surface can be used. It will be very good.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the core 8 used in the pressure dehydration step is the core 1 used in the heat drying step.
Although the structure is different from that of the core 8, the core 18 used in the heating and drying step may be used as the core used in the pressure dehydration step.

In the above embodiment, when the core 18 is inserted into and removed from the molded body 7 in the heating and drying step, the inside of the core 18 is vacuum-sucked into an elongated shape. Then, for example, a rod-shaped support member may be inserted into the core 18 and the core 18 may be twisted around the support member to form an elongated shape.

In the above embodiment, the papermaking / dewatering step and the heating / drying step are performed using separate molds. However, instead of this, no trace of the papermaking net remains or is noticeable on the surface of the molded product. By heating the papermaking mold after papermaking and dewatering to the extent that the papermaking and dewatering is not performed, the molded body after papermaking may be heated and dried simultaneously with pressure dehydration without being taken out of the papermaking mold.

Further, in the above embodiment, a set of papermaking molds is constituted by two split molds. However, a papermaking mold is constituted by three or more split molds according to the shape of the molded article. You may. The same applies to the heating type.

Further, as the papermaking mold, a male mold or a female mold of a pair of press molds composed of a male mold and a female mold may be used.

In the above embodiment, the shape of the cavity of the papermaking mold is not particularly limited as long as the shape of the cavity of the heating mold corresponds to the outer shape of the molded article to be molded. Although the above embodiment is an example of a method for manufacturing a bottle-shaped molded body, a box-shaped carton-shaped molded body and another shaped molded body can be manufactured instead. Furthermore, in addition to the shape of the container used to store the contents, various shapes that are free in design, such as objects such as ornaments, can be used.

[0033]

According to the method for producing a pulp molded article of the present invention, it is not necessary to provide the above-mentioned ventilation path, which is indispensable in the conventional heating mold, and the trace of the ventilation path is transferred to the molded article. Thus, a pulp molded article having a very smooth surface and a good appearance can be obtained without any risk. Further, according to the method for producing a pulp molded article of the present invention, since there is no need to provide the ventilation path, there is no possibility that the pulp fiber is clogged in the ventilation path.
Further, according to the method for producing a molded pulp molded article of the present invention, since there is no need to provide the ventilation path, the heat transfer efficiency is improved, and the drying efficiency of the molded article is improved. Also, the manufacturing cost of the heating mold is reduced.

[Brief description of the drawings]

FIG. 1 is a process chart sequentially showing a papermaking / dewatering step in an embodiment of the method for producing a pulp molded article of the present invention.

FIG. 2 is a schematic view showing a heating type structure.

FIG. 3 is a process chart sequentially showing a heating and drying step of a molded body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper-making mold 2, 30-piece mold 4 Cavity 5 Slurry inflow port 6 Communication path 7 Molded body 8 Core 10 Heating mold 18 Core 18a Outer layer 18b Inner layer 21 Vent hole

Claims (5)

[Claims] 1. A predetermined fluid is supplied into a scalable hollow core while a pulp molded body formed by papermaking and dewatered to a predetermined moisture content is heated to a predetermined temperature by a heating mold. A method for producing a pulp molded article, wherein the molded body is heated and dried by pressing the molded body toward the inner surface of the heating die by the expanded core. As a child, having an outer layer in contact with the molded body when the core is expanded, and an inner layer positioned inside the outer layer, wherein the inner layer is substantially impermeable to the fluid, When the outer layer presses the molded body by the expanded core, an air passage is formed between the molded body and the inner layer to exhaust water vapor generated by heating to the outside of the heating mold. Pulp mall using core Process for producing a molded article. 2. The method for producing a pulp molded article according to claim 1, wherein the outer layer is made of a knit, a woven fabric, or a nonwoven fabric. 3. The method for producing a pulp molded article according to claim 1, wherein the core has elasticity and can be expanded and contracted. 4. The method for producing a pulp molded article according to claim 1, wherein an air passage for exhausting water vapor generated by heating is not formed on an inner surface of the heating die. 5. The heating mold comprises a set of split dies, and a cavity having a predetermined shape is formed by combining the split dies, and the molded body is loaded in the cavity. The method for producing a pulp molded article according to any one of claims 1 to 4, wherein the core is expanded after inserting the core into the molded article.