JP3568874B2 - Mold for manufacturing pulp molded products - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a mold for producing a pulp molded article and a method for producing a pulp molded article using the production mold.
[0002]
Problems to be solved by the prior art and the invention
As a conventional technique relating to a mold for producing a pulp molded article, for example, a papermaking mold for a fiber molded article disclosed in Japanese Patent Application Laid-Open No. 8-49200 is disclosed. In this papermaking mold, a water guide passage (dispersion medium guide path) to the water absorption hole is formed on the side surface of the molding surface of the rigid body provided with the water absorption hole, and a net-like body is partially or entirely formed on the side surface. It is laid to increase the water absorption efficiency during papermaking.
[0003]
By the way, after forming a fiber molded body using this type of papermaking mold, the papermaking mold is placed together with the fiber molded body in a drying mold, and further deaerated through a water absorption hole and a water guide passage. When the fiber molded body is pressed and dried to perform drying, the pressing force in a portion corresponding to the water absorption hole or the water passage becomes lower than that in other parts. Therefore, after drying the fiber molded body, the fiber molded body is dried. Unnecessary transfer marks, which are convex and concave, remain on the inner and outer surfaces of the portion corresponding to the water absorption hole and the water guide passage, thus deteriorating the appearance of the molded product.
[0004]
Accordingly, an object of the present invention is to provide a production mold for a pulp molded article capable of suppressing the occurrence of unnecessary transfer marks on the inner and outer surfaces of the molded article, and a method for producing a pulp molded article using the same. It is in.
[0005]
The present inventors comprise a papermaking net disposed on a suction surface of a suction type having a suction path, a flexible net having a predetermined fluid permeability and rigidity, and a flexible net on which pulp is deposited, It has been found that the occurrence of transfer marks on the inner and outer surfaces of the dried molded article can be suppressed by suppressing the uneven pressing while securing the air permeability in the pressing / drying step.
[0006]
[Means for Solving the Problems]
The present invention has been made based on the above findings, and is a manufacturing die used in a manufacturing process of a pulp molded article, wherein the suction die is made of an elastically deformable elastic body having a suction passage therein. A flexible net having rigidity and fluid permeability that follows the elastic deformation of the suction mold and withstands the suction deformation through the suction passage; and is disposed outside the flexible net. there is provided a manufacturing mold of stretchable said suction-type elastic deformation following to the deformation and pulp molded article that has a flexible net pulp is deposited.
[0007]
Further, the present invention is a method for producing a pulp molded article using the production mold for a pulp molded article of the present invention, wherein a pulp slurry is supplied to the production mold, and the pulp slurry is sucked through the suction path. A pulp mold is formed by depositing pulp on the flexible net to form a pulp layer, then transferring the pulp layer together with the production mold to a drying mold, and pressing and drying the pulp layer on the inner surface of the drying mold. It is intended to provide a method for producing a molded article.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a production mold (hereinafter, simply referred to as a production mold) for a pulp molded article of the present invention will be described based on preferred embodiments thereof with reference to the accompanying drawings.
[0009]
FIG. 1 shows an embodiment of the production mold of the present invention. In the figure, reference numeral 1 indicates a production mold.
[0010]
As shown in FIG. 1, a manufacturing die 1 is for manufacturing a box-shaped molded body that opens upward, and includes a core (suction die) 2 having a suction path 20 therein and a core 2 having a suction path 20. It comprises a papermaking net 3 disposed on the suction surface 21, a flange 4 surrounding the upper part of the core 2, and a cap plate 5 covering the upper surface of the core 2.
[0011]
The core 2 has an outer shape slightly smaller than the outer shape of the molded body to be molded. However, the height of the core 2 is larger than the height (depth) of the molded body. The core 2 is made of an elastically deformable material. Examples of such materials include rubber-based materials such as silicone rubber, flexible rubber, and urethane rubber. The upper center of the core 2 is an open space and forms a chamber 22. Each side surface and bottom surface which form the outer surface of the core 2 has a network-like uneven pattern.
[0012]
A large number of the suction passages 20 are formed so as to communicate the chamber 22 with the outside of the core 2. The suction path 20 is formed radially from the inner surface of the chamber 22 to the outside of the core 2. The suction passage 20 is open at a suction surface 21 of the core 2. The number of openings of the suction passage 20 is preferably set to 1 to 4, particularly 1 to ² per 1 cm ² , in terms of dewatering efficiency of the pulp layer described later, and the core 2 is elastically deformed to form the papermaking net 3. This is preferable in that the strength of the core 2 is sufficiently maintained when the accumulated pulp is pressed. Further, the suction passage 20 has a cross section having such a size that the passage of the fluid is not hindered even if the core 2 is elastically deformed by pressing.
[0013]
The papermaking net 3 includes a flexible net 30 disposed on the suction surface 21 of the core 2 and a flexible net 31 disposed outside the flexible net 30 and on which pulp is deposited. . The tough net 30 and the flexible net 31 can be fixed by a method that does not impair the respective functions described below. For example, the peripheral edges of the flexible net 30 and the flexible net 31 can be fixed by weaving each other with a metal wire or the like.
[0014]
The flexible net 30 has fluid permeability and rigidity to withstand deformation due to suction through the suction path 20 (suction deformation) in the pressing / drying process. That is, in the state where the pulp layer is pressed and dried while being sucked through the suction path 20 in the pressing and drying step described later, the flexible net 30 itself has fluid permeability, of course. In addition, a flexible space having a rigidity that follows the elastic deformation of the core 2 and can withstand the suction deformation through the suction passage 20 while securing a permeation space for the fluid (water or water vapor) by suction through the suction passage 20. Things. Thus, in the pressing / drying step, a smooth suction surface without any unevenness can be formed while uniformly transmitting the pressing force to the pulp layer regardless of the uneven shape of the core 2.
[0015]
In order to obtain the above-described flexibility, the flexible net 30 has a deformation amount with respect to a load applied to a portion corresponding to the opening of the suction passage 20 of 0 to 5% with respect to the long diameter of the opening of the suction passage 20. Preferably, there is. Specifically, for example, when the additional load at the opening of the suction path 20 is 0.7 to 1.2 kg / (one suction path) and the inner diameter at the opening of the suction path 20 is 3 to 4 mm, It is preferable that the flexible net 30 does not deform under the additional load. The size of the mesh of the flexible net is preferably 15 to 60 mesh (JIS L0208, the same applies hereinafter), particularly 30 to 40 mesh from the viewpoint of fluid permeability. The flexible net 30 preferably has a thickness of 0.2 to 1.5 mm, particularly 0.5 to 0.8 mm in a state where the suction surface 21 of the core 2 is covered from the viewpoint of fluid permeability and shape retention. . Specifically, the flexible net 30 having such characteristics can be formed of a fiber mesh made of a material such as stainless steel, copper, brass, Kevlar, Teflon, nylon, and polyester.
[0016]
The flexible net 31 closely covers the surface of the flexible net 30. The flexible net 31 is also formed of a stretchable material that can be deformed following the elastic deformation of the core 2. The flexible net 31 needs to flow a fluid without being crushed even when the core 2 is elastically deformed. From this viewpoint, it is preferable that the flexible net 31 is made of a material having elasticity and fluid circulation. The stretchability (extensibility) in the covered state covering the surface of the flexible net is preferably 20 to 200%, particularly preferably 20 to 80%. In addition, in terms of water permeability and air permeability, the flexible net 31 may have a thickness of 0.4 to 1.2 mm, particularly 0.5 to 0.8 mm in a state where the surface of the flexible net 30 is covered. preferable.
[0017]
The flexible net 31 also functions as a papermaking net when forming a pulp layer. Therefore, the flexible net 31 has a mesh that allows moisture in the pulp slurry to pass but does not allow pulp fibers to pass. The size of the mesh is preferably 25 to 60 mesh, particularly 30 to 40 mesh, from the viewpoint of the moldability of the pulp layer and the prevention of clogging of the pulp fiber. The flexible net 31 has an average open area ratio of 40 to 80%, particularly 40 to 50% when the flexible net 31 is in close contact with the surface of the flexible net, and has a water absorbing property, air permeability and strength. It is preferable from the point of view.
[0018]
Considering the above points comprehensively, a knitted fabric formed of a natural fiber or a synthetic fiber is preferably used as the flexible net 31, particularly following the elastic deformation of the core 2 when pressing the pulp layer. It is preferable to use a knitted fabric made of a synthetic fiber such as nylon, polyester, or Teflon from the viewpoints of properties and elasticity required for releasing after pressing.
[0019]
The flange 4 surrounds the periphery of the upper part of the core 2 and has a rectangular outer shape in plan view. The flange 4 is fixed to the core 2 by a predetermined means. The flange 4 is made of a rigid body such as metal, ceramics, resin, etc., and does not substantially deform even when an external force is applied. As a result, as will be described later, when a flange is formed on the molded body, the finished state of the flange is improved.
[0020]
The cap plate 5 has a rectangular shape in plan view, and has the same outer shape as the flange 4. A through hole is formed in the periphery of the cap plate 5. On the other hand, screw holes are formed at corresponding positions of the flange 4. Then, in a state where the production die 1 is assembled, the screw 50 is passed through the through hole of the cap plate 5 and the screw 50 is passed through the screw hole formed in the flange 4 and is screwed, so that the cap plate 5 becomes the core. 2 is fixed.
[0021]
A screw hole 51 is formed substantially at the center of the cap plate 5, and a suction pipe 52 is screwed into the screw hole 51. As a result, in a state where the production mold 1 is assembled, the suction pipe 52, the chamber 22, the suction path 20, and the papermaking net 3 communicate with each other to form a flow passage communicating the outside and the inside of the production mold 1. You.
[0022]
Next, a pulp molded article of the present invention will be described with reference to the drawings based on an embodiment using the production die 1 as a preferred embodiment.
[0023]
FIG. 2 sequentially shows each step in the method for manufacturing a pulp molded article of the present embodiment. Specifically, (a) is a papermaking step, (b) is a lifting step of the production mold, (c) is a step of inserting the production mold into the drying mold, (d) is a step of pushing the production mold into the drying mold, e) is a pressing and drying step, and (f) is a demolding step.
[0024]
First, as shown in FIG. 2A, the production mold 1 is immersed in a container 6 filled with pulp slurry. While the production die 1 is immersed in the pulp slurry, the pulp slurry is sucked by suction means (not shown) such as a suction pump connected to the suction pipe 52. The suction is performed through the above-mentioned flow passage. That is, moisture in the pulp slurry is sucked through the flow passage, and pulp fibers are deposited on the surface of the papermaking net 3 provided on the suction surface 21 of the production mold 1 to form a humid pulp layer. Is done. As described above, since a predetermined space exists between the suction surface 21 of the core 2 and the papermaking net 3 and the flow of water is ensured, the pulp fiber is deposited smoothly and uniformly. A pulp layer having an appropriate thickness is formed. As described above, the core 2 is made of an elastically deformable material. In addition, the core 2 preferably has such a rigidity that the core 2 is not deformed by the suction.
[0025]
The pulp slurry used in the present invention may be composed of pulp fiber and water, or in addition to these, inorganic materials such as talc and kaolinite, inorganic fibers such as glass fiber and carbon fiber, and synthetic resin powder such as polyolefin. Alternatively, it may contain components such as fiber, non-wood or vegetable fiber, and polysaccharide. The compounding amount of these components is preferably 1 to 70% by weight, particularly preferably 5 to 50% by weight based on the total amount of the pulp fiber and the components. The pulp fibers are preferably wood pulp such as softwood or hardwood or non-wood pulp such as bamboo or straw. The length and thickness of the pulp fiber are preferably 0.1 mm or more and 10 mm or less, and 0.01 mm or more and 0.05 mm or less. The pulp slurry preferably has a temperature of 40 to 120 ° C. from the viewpoint of improving the dewatering efficiency and the like.
[0026]
When the pulp layer 7 having a predetermined thickness is formed, the production mold 1 is pulled out of the pulp slurry as shown in FIG. 2B, and suction is continuously performed through the suction pipe 52 to dehydrate the pulp layer 7 and to remove the water. The rate is set to a predetermined value. The moisture content of the pulp layer after the suction dehydration is 60 to 95% by weight, particularly 60 to 80% by weight, in that the pulp layer 7 can be sufficiently held on the surface of the production mold 1 by suction, and is maintained. This is preferable because the production mold 1 can be transported without the pulp layer falling off. The suction pressure at the time of dehydration is 0.01 to 0.1 Pa, preferably 0.03 to 0.08 Pa. Then, in such a pressure range, the deformation amount of the flexible net 30 with respect to the load applied to the portion corresponding to the opening of the suction passage 20 is 0 to 5% with respect to the long diameter of the opening of the suction passage 20 as described above. It is.
[0027]
When the pulp layer 7 can be sucked and dehydrated to a predetermined moisture content, as shown in FIG. 2C, the production mold 1 on which the pulp layer 7 is formed is opened with a shape corresponding to the outer shape of the molded article to be molded. The pulp layer 7 is inserted into the concave portion 80 of the drying mold 8 having the concave portion, and the pulp layer 7 is subjected to pressure dehydration, shape provision, and heat drying in the concave portion 80. In the present embodiment, the drying mold 8 is composed of one member, but two or more split molds are combined in accordance with the shape of the molded body to be molded (for example, a complicated shape or a shape having an undercut). A dry mold may be configured.
[0028]
The drying mold 8 is previously heated to a predetermined temperature by a heating means 81 such as an electric heater. Further, the inner surface of the concave portion 80 of the drying mold 8 is not provided with an air passage for discharging the moisture generated from the pulp layer 7, that is, water or steam, and the inner surface is made smooth. Further, a ventilation hole 82 is formed in a surface of the drying die 8 on which the molded body is formed (in the present embodiment, a peripheral surface of the concave portion 80 of the drying die 8). The ventilation hole 82 is connected to a supply source of air (not shown).
[0029]
The insertion is performed such that the bottom of the pulp layer 7 first contacts the bottom of the concave portion 80 of the drying mold 8. Next, as shown in FIG. 2D, the production die 1 is further pushed in and pressed. Due to this pressing, the core 2 in the manufacturing die 1 is deformed so as to follow the inner surface of the concave portion 80 of the drying die 8, and the space of the concave portion 80 is completely filled. In this state, the flexible net 30 constituting the papermaking net 3 follows the elastic deformation of the core 2 while securing a fluid permeating space between the flexible net 30 and the suction surface 21 of the core 2 and uniformly applies the pressing force to the pulp. Form a smooth plane without any irregularities that can be transmitted. Further, the flexible net 31 covering the surface also extends so as to follow this.
[0030]
As a result, the pulp layer 7 formed on the papermaking net 3 is further substantially uniformly pressed and dewatered under pressure, and the inner shape of the concave portion 80 is transferred to the pulp layer 7. Further, the pulp layer formed on the lower surface of the flange 4 in the production die 1 is pressed between the lower surface and the upper surface of the drying die 8. This portion becomes a flange portion in the obtained molded body. As described above, since the flange 4 is formed of a rigid body and is not substantially deformed by the pressing, the pressing is uniformly and effectively performed, and the finished state of the flange portion is improved.
[0031]
The suction through the suction pipe 52 in the manufacturing die 1 is continued while the pressed state of the manufacturing die 1 is maintained. As described above, since the papermaking net 3 arranged on the outer surface of the production mold 1 can flow a fluid without being crushed even under the pressing state of the production mold 1, the water contained in the pulp layer 7 by the suction is provided. Is discharged out of the production mold 1 through the flow passage. Water vapor generated by drying the pulp layer 7 is also discharged out of the production mold 1 through the same route.
[0032]
The pulp layer 7 is dried by keeping the pressed state of the production mold 1 for a predetermined time to obtain a pulp molded article as an object. Next, the pressing of the production mold 1 is stopped. As a result, as shown in FIG. 2 (e), the core 2 of the production mold 1 returns to the shape before pressing, and the obtained pulp molded article 70 is released from the papermaking net 3 of the production mold 1 and dried. In the recess 80.
[0033]
Next, the production mold 1 is taken out of the drying mold 8. After the production mold 1 is taken out, air is blown from the surface of the drying mold 8 on which the molded body 70 is formed (the peripheral surface of the concave portion of the drying mold in the present embodiment) to the molded body 70 through the ventilation holes 82 of the drying mold 8. Spray. As a result, a gap is formed between the surface and the outer surface of the molded body 70, and the molded body 70 is released from the drying mold 8. Further, as shown in FIG. 2F, the pulp molded article 70 is taken out from the recess 80.
[0034]
The pulp molded article 70 thus manufactured is a box-shaped hollow molded article having an opening, and has a flange portion extending outward from the periphery of the opening.
[0035]
As described above, according to the present embodiment, the papermaking net 3 including the flexible net 30 and the flexible net 31 is disposed on the surface of the core 2 of the manufacturing die 1, and the core 2 is dried in the pressing / drying step. When pressing and drying the concave portion 30 of the mold 3, the flexible net 30 disposed on the suction surface 21 of the core 2 uniformly transmits the pressing force while securing a fluid permeating space to form a smooth flat surface. As a result, unnecessary transfer marks on the inner and outer surfaces of the molded body 70 can be suppressed. In the present embodiment, in particular, since a ventilation path for discharging water and water vapor out of the mold is not formed on the inner surface of the drying mold 8, the surface of the pulp molded article becomes smooth, and the appearance of the molded article becomes extremely Become good. Further, in forming the flange portion of the molded body 70, pressing is performed between the lower surface of the rigid flange 4 and the upper surface of the drying mold 8, so that the finished state of the flange portion is improved. Further, when the molded body is taken out from the drying mold 8, air is blown from the molding surface 21 of the molded body toward the molded body 70, so that the molded body 70 is released from the drying mold very smoothly.
[0036]
The present invention is not limited to the above embodiment.
[0037]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the unnecessary transfer mark on the inner and outer surfaces of a pulp molded article can be suppressed.
[Brief description of the drawings]
FIG. 1 is a schematic longitudinal sectional view showing one embodiment of a production mold for a pulp molded article of the present invention.
FIGS. 2A and 2B are schematic diagrams showing schematic steps of a method for producing a pulp molded article of the present invention, wherein FIG. (D) is a step of pushing a production die into a drying die, (e) is a pressing / drying step, and (f) is a demolding step.
[Explanation of symbols]
1: Production mold for pulp molded article 2: Core (suction type)
3: Papermaking net 7: Pulp layer 20: Suction path 21: Suction surface 30: Flexible net 31: Flexible net

Claims (2)

A manufacturing die used in a manufacturing process of a pulp molded article, comprising: a suction mold made of an elastically deformable elastic body having a suction passage therein; and a suction mold disposed on a suction surface of the suction mold. A flexible net having rigidity and fluid permeability that follows the deformation and withstands the suction deformation through the suction path; and a flexible net that is disposed outside the flexible net and that can expand and contract to follow the elastic deformation of the suction mold. and and manufacturing type of pulp molded article that has a flexible net pulp is deposited. A method for producing a pulp molded article using a production mold for a pulp molded article according to claim 1, wherein a pulp slurry is supplied to the production mold, and the pulp slurry is sucked through the suction path to obtain the flexibility. A method for producing a pulp molded article in which, after depositing pulp on a net to form a pulp layer, the pulp layer is transferred to a drying mold together with the production mold, and the pulp layer is dried while pressing the pulp layer against the inner surface of the drying mold. .

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