JP2000226800A - Production of pulp-molded bodies - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce pulp-molded bodies having a complicated shape in a short time without occurrence of joint to be formed by sticking the molded products to each other on their surfaces. SOLUTION: The insertion part 7 equipped with the core 8 having the passage of the compressed fluid and with a hollow or bag-type covering material 9 that is to be inserted into the core 8 is inserted into the cavity 4 formed by assembling a pair of split molds 2, 3 for paper making. Then, compressed fluid is fed via the fluid communication into the covering material 9 to swell the hollow part or the bag in a prescribed size, thus the volume in the cavity 4 is reduced to 5-90% based on the original volume. Then, the pulp slurry is poured, dehydrated and dried to give the objective pulp molded product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a pulp molded article capable of shortening the production cycle time.

[0002]

2. Description of the Related Art In the production of a pulp molded article, a pair of split molds comprising a male mold and a female mold is used, and a pulp slurry is introduced between the two molds. Known methods include dewatering the slurry to produce shallow trays and dishes, and also producing bottles and the like by forming a splitter using a pair of split dies and bonding two splitters together. Have been.

However, with these methods, it is not easy to produce a molded article having a complicated shape, and a seam is formed on the surface by bonding, resulting in impaired strength and appearance. Further, since a bonding step is required in addition to the paper making step, the manufacturing cycle time is lengthened.

Accordingly, an object of the present invention is to provide a method for producing a pulp molded article which can produce a molded article having a complicated shape in a short time without causing a seam by bonding to the surface. .

[0005]

According to the present invention, a pulp slurry is injected into a cavity of a mold having a cavity shape corresponding to a pulp molded article formed by abutting a pair of papermaking split dies. A pulp layer is formed on the inner surface of the cavity by dehydrating the inside, and the pulp layer is dried to obtain a pulp molded body, wherein the volume of the cavity is reduced. The above object has been achieved by providing a method for producing a pulp molded article in which the pulp slurry is injected into the cavity after inserting the insertion member having the above into the cavity.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a paper making step of the steps of the first embodiment of the present invention. First, as shown in FIG.
A mold 1 is prepared in which a cavity 4 having a shape corresponding to the outer shape of a pulp molded article to be molded (hereinafter, also simply referred to as a molded article) is formed by abutting the pieces 3. Each of the split dies 2 and 3 is provided with a plurality of communication holes 5 communicating with the cavities 4 from the outer surfaces thereof. The inner surfaces of the split dies 2 and 3 are covered with nets (not shown) each having a mesh of a predetermined size.

When the two halves 2 and 3 are abutted with each other, an opening 6 communicating with the cavity 4 is formed in the upper part of the mold 1 as shown in FIG. Under this condition, the insertion member 7 is inserted into the cavity 4 through the mouth 6. The insertion member 7 includes a core 8 and a hollow or bag-shaped covering member 9 into which the core 8 is inserted, and both are fixed to the fixing plate 11 by predetermined means. The core 8 has a cylindrical shape, and has a large number of holes 10 on its side surface. One end 8a of the core 8 is exposed to the outside through the fixing plate 11,
It is connected to a supply source of a pressurized fluid (not shown). As a result, the cover member 9 is inserted into the insertion member 7 from one end 8a of the core 8 through the inside of the core 8 and through the hole 10 on the side surface of the core 8.
A communication path leading to the inside is formed. The covering member 9 is formed of a hollow elastic body that can expand and contract or a bag-like body that does not expand and contract. When the covering member 9 is made of an elastic body, the elastic body has an elastic force regardless of the presence or absence of the core 8, so that the elastic body does not come into contact with the inner surface of the cavity 4 at the time of preliminary expansion described later. Can be easily done. On the other hand, when the covering member 9 is formed of a bag-like body that does not expand and contract, the inside of the core 8 is depressurized to adhere the bag-like body to the surface of the core 8, so that the bag is formed when the pulp layer 13 described later is formed. It is possible to prevent the state body from contacting the inner surface of the cavity 4. In the present embodiment, an elastic body is used as the covering member 9. The elastic body is formed of urethane, fluorine-based rubber, silicone-based rubber, elastomer, or the like, which is excellent in tensile strength, rebound resilience, stretchability, and the like. On the other hand, the bag that does not expand and contract is formed of, for example, polyethylene or polypropylene.

When the insertion member 7 is inserted into the cavity 4 and the mouth 6 is closed by the fixing plate 11, FIG.
As shown in (b), a predetermined pressurized fluid is supplied from the supply source of the pressurized fluid into the inside of the covering member 9 through the communication path. Thereby, the covering member 9 is pre-expanded to a predetermined size. The shape of the pre-expanded covering member 9 becomes a substantially flat plate shape. As the pressurized fluid used to expand the covering member 9, for example, compressed air (heated air), oil (heated oil), and other various liquids are used. Where "expansion"
This means that when the covering member 9 extends and its volume increases (for example, when the covering member 9 is made of a stretchable elastic body), the covering member 9 itself does not extend but its volume increases. (For example, when the covering member 9 is formed of a bag-like body that does not expand and contract, and the bag-like body is attached to the surface of the core 8 in a reduced pressure state). "Has the same meaning as this.)

When a pulp molded article having a predetermined weight is formed, the volume of the insertion member 7 increases due to the pre-expansion, and the volume in the cavity 4 decreases accordingly. As a result, the amount of water in the pulp slurry injected into the cavity 4 can be reduced, and the pulp slurry having a higher concentration can be injected as compared with the case where the insertion member 7 is not inserted. Thus, the cavity 4 can be filled with the pulp slurry. Therefore, the production cycle time such as the injection time of the pulp slurry can be shortened. Moreover, since the volume of the insertion member 7 is increased in the cavity 4, the insertion member 7 can be effectively used even when a bottle-shaped molded body having a smaller cross-sectional area than the cross-sectional area of the body is formed. Can be used. Due to the pre-expansion, the volume of the cavity 4 is preferably reduced by 5 to 90%, particularly preferably 40 to 75%, before the insertion of the insertion member 7.

When the covering member 9 is pre-expanded, no part of the insertion member 7 is in contact with the inner surface of the cavity 4 as shown in FIG. Thereby, the thickness variation of the pulp layer 13 described later can be suppressed. In this state, the slurry is injected into the cavity 4 from the injection portion 12 of the pulp slurry provided on the fixed plate 11. As a result, the moisture of the pulp slurry is
Is discharged to the outside of the mold 1 and the pulp fibers are deposited on the inner surface of the cavity 4. As a result, the pulp layer 1 on which the pulp fibers are deposited
3 is formed.

When a predetermined amount of pulp slurry is injected,
The injection is stopped and the inside of the cavity 4 is completely sucked and dehydrated. Subsequently, as shown in FIG. 1C, a pressurized fluid is further supplied into the covering member 9 to further expand the covering member 9.
Thereby, the pulp layer 13 is pressed against the inner surface of the cavity 4. As a result, the pulp layer 13 is pressed against the inner surface of the cavity 4, and the inner surface shape of the cavity 4 is transferred to the pulp layer 13 and the pressure dehydration proceeds. The pulp layer 13 having a water content of 70 to 80% by weight due to the suction and dehydration has a water content of 55 to 7 when pressed by the covering member 9.
It is preferably 0%. Thus, cavity 4
Since the pulp layer 13 is pressed against the inner surface of the cavity 4 from the inside, the shape of the inner surface of the cavity 4 is accurately transferred to the pulp layer 13 even if the shape of the inner surface of the cavity 4 is complicated. Further, as compared with the case where the injection nozzle is pulled out after the slurry injection and then the elastic body for the pressure dehydration is inserted, the pressurized dewatering can be performed immediately after the pulp slurry is injected into the cavity 4, so that the machine operation time can be reduced, Cycle time can be reduced. In addition, unlike the conventional manufacturing method, there is no need to use a bonding step, so that the obtained molded article does not have a seam or a thick portion due to bonding. As a result, the strength of the obtained pulp molded article is increased and the appearance impression is improved. Moreover, since there is no need to perform a separate laminating step in addition to the paper making step, the manufacturing cycle time can be reduced. The supply pressure of the pressurized fluid during pressurized dehydration is 0.01 to 5 MPa,
In particular, it is preferably 0.1 to 3 MPa.

When the shape of the inner surface of the cavity 4 is sufficiently transferred to the pulp layer 13 and the pulp layer 13 can be dehydrated to a predetermined moisture content, as shown in FIG. Pull out. Then, the covering member 9 shrinks and returns to the original size. Next, the insertion member 7 is taken out of the cavity 4, and the mold 1 is further opened to take out the wet pulp molded product intermediate 14 having a predetermined moisture content.

The removed intermediate 14 is then subjected to a heating and drying step. In the heating / drying step, substantially the same operation as in the paper making step shown in FIG. 1 is performed except that the paper making / dewatering is not performed. That is, first, a heating and drying mold in which a cavity having a shape corresponding to the outer shape of a pulp molded article to be molded is formed by abutting a pair of split molds is heated to a predetermined temperature. The intermediate in a wet state is charged into the cavity of the mold.

Next, the inside of the cavity is suctioned and depressurized, and a hollow or bag-shaped core is inserted into the cavity. Then, a pressurized fluid is supplied into the core to expand the core, and the expanded core presses the intermediate body against the inner surface of the cavity. The material of the core and the supply pressure of the pressurized fluid can be the same as in the papermaking process. That is,
As the core, a hollow body made of an elastic body having elasticity and elasticity, or a bag-shaped body made of a film such as polypropylene or polyethylene can be used. In this state, the intermediate is dried by heating. When the intermediate has dried sufficiently, the pressurized fluid in the core is drained and the core is shrunk and removed. Further, the heating and drying mold is opened, and the molded pulp molded product is taken out.

The pulp molded article 20 thus obtained has an opening 21, a body 22 and a bottom 23 as shown in FIG.
Is used as a hollow container suitable for accommodating contents such as powders and granules. Further, in this pulp molded body 20, the angle formed between the ground surface of the bottom portion 23 and the outer surface of the side wall of the body portion 22 is substantially 90 ° on both the front and rear walls and the left and right walls constituting the body portion 22. I have. In addition, the height is 50 mm or more, preferably 100 m
m or more. Although the container is a deep-bottomed container and is manufactured by the above-described method despite the fact that the concave portion 24 is formed, the molded body 20 is
There is no seam for bonding in No. 2. In addition, the outer surface and the inner surface are smooth. In particular, the center line average roughness (Ra) is 50 μm or less, and the maximum height (Ry) is 500 μm or less.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a schematic diagram showing a paper making step of the steps of the present embodiment. This embodiment is the same as the first embodiment except that the configuration of the insertion member and the pressing and dewatering steps of the pulp layer are different, and the description of the first embodiment is appropriately applied to the points that are not particularly described. In FIG. 3, the same members as those in FIG. 1 are denoted by the same reference numerals.

First, as shown in FIG. 3A, an insertion member 7 is inserted into a cavity 4 formed in a mold 1 in which a pair of split dies 2 and 3 are butted. The insertion member 7 of the present embodiment is formed of a thick rod-shaped body having one end fixed to the fixing plate 11. FIG. 3A shows a state where the rod-shaped body is viewed from the side. As this rod-shaped body, one having a volume sufficient to sufficiently reduce the volume of the cavity 4 when inserted into the cavity 4 is used. Preferably, the volume of the cavity 4 is 5 to
It is preferable to use a material having a volume sufficient to reduce it by 90%, more preferably 40 to 75%, from the viewpoint of improving the efficiency such as shortening the manufacturing cycle time. In such a case, the rod-shaped body may be any of a solid body and a hollow body. When the insertion member 7 is inserted, no part of the insertion member 7 contacts the inner surface of the cavity 4 as in the first embodiment.

Next, as shown in FIG. 3B, the pulp slurry is injected into the cavity 4 from the pulp slurry injection section 12 with the insertion member 7 inserted and the mouth 6 closed. As a result, the water in the pulp slurry is discharged to the outside of the mold 1 through the communication hole 5 and the pulp fibers are deposited on the inner surface of the cavity 4, and the pulp layer 13
Is formed. In this case, since the insertion member 7 is inserted into the cavity 4, the volume of the cavity 4 is reduced,
The amount of water in the pulp slurry to be injected into the cavity 4 can be reduced as compared with the case where the insertion member is not inserted. That is, since a high-concentration pulp slurry can be injected, the injection time of the pulp slurry can be shortened, and the same effect as in the first embodiment can be obtained. The pulp slurry may be injected through the inside of the insertion member 7.

When a predetermined amount of pulp slurry is injected,
The injection is stopped and the inside of the cavity 4 is completely sucked and dehydrated. Subsequently, as shown in FIG. 3C, the insertion member 7 is pulled out of the cavity 4.

Next, as shown in FIG. 3D, the inside of the cavity 4 is suctioned and decompressed, and a core 15 which is elastic, stretchable and hollow is inserted into the cavity 4. As the core 15, the same one as that used in the heating and drying step in the first embodiment can be used.

Next, as shown in FIG.
The core 15 is expanded by supplying a pressurized fluid into the inside, and the pulp layer 13 is pressed against the inner surface of the cavity 4 by the expanded core 15 so that the inner surface shape of the cavity 4 is transferred to the pulp layer 13. 13 is further dehydrated. The type and supply pressure of the pressurized fluid can be the same as the supply pressure in the heating and drying step in the first embodiment.

When the shape of the inner surface of the cavity 4 is sufficiently transferred to the pulp layer 13 and the pulp layer 13 can be dehydrated to a predetermined moisture content, as shown in FIG. And the core 15 is contracted to its original size.
Then, the contracted core 15 is taken out from the cavity 4, the mold 1 is opened, and the wet pulp molded article 14 having a predetermined moisture content is taken out.

The subsequent steps are the same as the heating and drying step in the first embodiment.

The present invention is not limited to the embodiments described above,
For example, the shape of the pre-expanded covering member in the first embodiment and the shape of the insertion member in the second embodiment are as follows.
Various shapes can be used depending on the shape of the pulp molded article to be molded. In addition, after molding of the molded body 20, a plastic layer or a coating layer is provided on the outer surface and / or the inner surface thereof to further enhance the strength of the molded body 20, effectively prevent leakage of contents, and the like. Or you may give decoration. Further, a reinforcing member made of plastic or the like may be disposed in a portion to which a load is applied when the molded body 20 is used, for example, the opening 21 or the bottom 23 to improve the durability of the molded body 20. Further, some of these parts may be formed of plastic or the like. Further, the molded article of the present invention may be a bottle-shaped container in which the opening area of the opening is smaller than the cross-sectional area of the body. Further, the manufacturing method of the present invention may be applied to a method of manufacturing an object such as an ornament, in addition to a method of manufacturing a hollow body (hollow container) used for storing contents.

[0025]

According to the method for producing a pulp molded article of the present invention, a molded article having a complicated shape can be produced in a short time without causing a seam due to bonding on the surface. In particular, the manufacturing method of the first embodiment includes:
This is effective when molding a bottle-shaped molded body in which the cross-sectional area of the opening is smaller than the cross-sectional area of the body.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a paper making process among processes of a first embodiment of the present invention.

FIG. 2 is a perspective view showing a pulp molded article manufactured according to the first embodiment.

FIG. 3 is a schematic diagram (corresponding to FIG. 1) showing a paper making process among processes of a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 mold 2, 30 split mold 4 cavity 7 insertion member 8 core 9 covering member 15 core 20 pulp molded product

[Procedure amendment]

[Submission date] March 1, 2000 (200.3.1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

Claims (5)

[Claims] 1. A pulp slurry is injected into a cavity of a mold having a cavity shape corresponding to a pulp molded article formed by abutting a pair of papermaking split dies,
A method for manufacturing a pulp molded article, comprising: forming a pulp layer on the inner surface of the cavity by dehydrating the inside of the cavity; and drying the pulp layer to obtain a pulp molded article, wherein the volume in the cavity is reduced. A method for producing a pulp molded article, comprising inserting an insertion member having a volume to be inserted into the cavity, and then injecting the pulp slurry into the cavity. 2. The insertion member includes a core having a communication passage for pressurized fluid, and a hollow or bag-shaped covering member into which the core is inserted, wherein the insertion member is inserted into the cavity. 2. The pulp molded article according to claim 1, wherein the pulp slurry is injected after the pressurized fluid is supplied into the covering member through the communication passage to pre-expand the covering member to a predetermined size. Manufacturing method. 3. The method for producing a pulp molded article according to claim 2, wherein after the formation of the pulp layer, the covering member is further expanded, and the pulp layer is pressed against the inner surface of the cavity by the expanded covering member. . 4. The method for producing a pulp molded article according to claim 1, wherein the insertion member is formed of a solid or hollow body having a predetermined shape. 5. After the formation of the pulp layer, the insertion member is pulled out, and then a hollow or bag-shaped core is inserted into the cavity, and a pressurized fluid is supplied into the core to supply the fluid. 5. The method for producing a pulp molded article according to claim 4, wherein the pulp layer is pressed against the inner surface of the cavity by the expanded core.