JP3249794B2 - Method for producing pulp molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pulp molded article capable of easily producing a molded article having a desired shape, and a papermaking mold for producing a pulp molded article.

[0002]

2. Description of the Related Art As a prior art relating to a method of manufacturing a pulp molded article using an elastic pressing die, there is, for example, Japanese Patent Application Laid-Open No. 5-279.
No. 998 is known. In the above publication, the pulp component is taken out on a papermaking net,
The molded pulp component is pressed by a pressing die made of an elastic material formed in a container shape, and then pressed under heating by a press die having a container shape to produce a molded article.

[0003] However, when the container intermediate obtained by pressing the pulp component by the pressing die is transferred to the press die, the container intermediate is in close contact with the papermaking net, so that the releasability is low. Poorly, the production efficiency is reduced, and the container intermediate may be damaged depending on the release method.

[0004] Accordingly, an object of the present invention is to provide a method for producing a pulp molded article having good mold release properties and capable of producing a molded article with high production efficiency.

[0005]

According to the present invention, an elastically deformable papermaking mold having a communication passage communicating from the outside to the inside is immersed in pulp slurry, and the papermaking mold is externally and internally formed through the communication passage. A pulp layer is formed on the surface of the papermaking mold by sucking moisture in the pulp slurry toward the pulp slurry. The papermaking mold, on which the pulp layer is formed, is inserted into the female mold concave portion, which is fixed at the portion and covers the upper surface of the concave portion, while extending and deforming the stretchable sheet, thereby forming the pulp layer. So that the bottom is in contact with the bottom of the recess through the stretchable sheet,
Further, the above object is achieved by providing a method of manufacturing a pulp molded article in which the papermaking mold is pressed and deformed so as to follow the shape of the recess, and the shape of the recess is transferred to the pulp layer to form a molded article. It was done. Again
Ming has a communication passage communicating from the inside to the outside and has an elastic deformation.
Formable paper mold and concave shape corresponding to the outer shape of the molded product
And a stretchable sheet is fixed at the periphery of the concave portion.
And a female mold covering the upper surface of the recess.
Of pulp molded products having fluid permeability
An apparatus is provided.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on preferred embodiments with reference to the drawings. In FIG.
1 is a longitudinal sectional view of a papermaking mold 1 used in a first embodiment of a method for producing a pulp molded article of the present invention.
The present embodiment relates to the manufacture of a box-shaped molded body having an opening. A papermaking mold 1 used in the present embodiment includes a core 10, a fluid-permeable material 2 covering the outer surface of the core 10.
0, a flange 30 surrounding the upper part of the core 10, and a cap plate 40 covering the upper surface of the core 10.

The core 10 has an outer shape slightly smaller than the outer shape of the molded body to be molded. However, the height of the core 10 is larger than the height (depth) of the molded body.
The core 10 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 10 is an open space and forms a chamber 11. Each of the side surfaces and the bottom surface forming the outer surface of the core 10 has a mesh-like uneven pattern.

A chamber 1 is provided on the inner surface of the chamber 11.
A plurality of fluid communication passages 12 communicating from one to the outside of the core 10
Are formed. The fluid communication passage 12 is provided in the chamber 11
Are formed radially from the inner surface to the outside of the core 10. The fluid communication passage 12 is open on the outer surface of the core 10, and the opening is 1 to 1 cm ^{2 on the} outer surface.
The formation of four, especially one or two, improves the dewatering efficiency of the pulp layer described later, and the strength of the core 10 is sufficiently maintained when the core 10 is elastically deformed and presses the pulp layer. Preferred from the point. The fluid communication passage 12 is provided in the core 10.
Has a cross section large enough to prevent the passage of fluid even if it is elastically deformed by pressing.

The fluid permeable material 20 covers the outer side surface and the bottom surface of the core 10 in close contact with the surface shape. As described above, since the outer surface of the core 10 has a mesh-like uneven pattern, the fluid-permeable material 20
Even when the outer surface of the core 10 is tightly covered, a predetermined space exists between the fluid-permeable material 20 and the outer surface of the core 10.

The fluid-permeable material 20 is made of a stretchable material that can be deformed following the elastic deformation of the core 10. Further, the fluid-permeable material 20 can form a fluid flow passage in the thickness direction. This flow passage is used for discharging water and steam generated from the pulp layer to the outside of the papermaking mold 1 when the pulp layer described later is dehydrated and dried. Therefore, it is necessary for the flow passage to flow the fluid without being crushed even when the core 10 is elastically deformed.
From this viewpoint, it is preferable that the fluid-permeable material 20 is made of a material that is thick and elastic and has fluid flowability. Specifically, the fluid-permeable material 20 is
The thickness in a state where the outer surface of the core 10 is covered is 0.1 to
It is preferably 10 mm, especially 0.1 to 2 mm.
Further, the stretchability (extensibility) in a state where the outer surface of the core 10 is covered is preferably 5 to 30%, particularly preferably 10 to 20%.

The fluid-permeable material 20 also functions as a papermaking net when forming a pulp layer. Therefore, the fluid-permeable material 20 has a mesh that allows moisture in the pulp slurry to pass but does not allow pulp fibers to pass. The size of this mesh is 10-80 mesh, especially 3
A mesh size of 0 to 50 is preferable from the viewpoint of the moldability of the pulp layer and the prevention of clogging of pulp fibers. The fluid permeable material 20 has an average open area ratio of 10 to 80%, particularly 2 when the outer surface of the core 10 is in close contact with the fluid.
It is preferable that it is 0 to 40% from the viewpoint of water absorption, air permeability and strength.

Considering the above points comprehensively, knits, woven fabrics and non-woven fabrics are preferably used as the fluid-permeable material 20. Particularly, the point that the pulp layer is pressed well and It is preferable to use a knitted fabric from the viewpoint that elasticity is required for the mold release.

The flange 30 surrounds the periphery of the upper part of the core 10 and has a rectangular outer shape in plan view.
The flange 30 is fixed to the core 10 by a predetermined means.

The cap plate 40 has a rectangular shape in plan view, and has the same outer shape as the flange 30. A through hole is formed in the periphery of the cap plate 40. On the other hand, a threaded hole is formed at a position corresponding to the flange 30. In the state where the papermaking mold 1 is assembled, the screw 41 is passed through the through hole of the cap plate 40, and the screw 41 is passed through the hole formed in the flange 30 and screwed, so that the cap plate 40 is
Are fixed to the core 10.

At a substantially central portion of the cap plate 40, a threaded through hole is formed, and a suction pipe 42 is screwed into the through hole. As a result, when the papermaking mold 1 is assembled, the suction pipe 42, the chamber 11, the fluid flow hole 12, and the fluid permeable material 20
Communicate with each other to form a communication passage communicating from outside to inside of the papermaking mold 1.

Next, a method of manufacturing a pulp molded article of the first embodiment using the papermaking mold 1 will be described. FIG. 2 shows the respective steps in the method for producing a pulp molded article of the present embodiment in order. Specifically, (a) is a paper making step, (b) is a pulling-up step of a paper making mold, and (c) is The step of inserting the papermaking mold into the female mold, the step (d) of pushing the papermaking mold into the female mold, the step (e) of pressing the papermaking mold, and the step (f) of taking out the papermaking mold and the molded body.

First, as shown in FIG. 2A, a papermaking mold 1 is immersed in a container 3 filled with a pulp slurry 2.
While the papermaking mold 1 is immersed in the pulp slurry 2, the papermaking mold 1 is sucked from outside to inside by suction means (not shown) such as a pump connected to a suction pipe 42. The suction is performed through the communication path described above. That is,
Moisture in the pulp slurry 2 is sucked through the communication path, and a water-containing pulp layer formed by depositing pulp fibers is formed on the surface of the papermaking mold 1, that is, the surface of the fluid-permeable material 20. As described above, since a predetermined space exists between the outer surface of the core 10 and the fluid-permeable material 20 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 10 is made of a material that can be elastically deformed. In addition to this, it is preferable that the core 10 has such a rigidity that it is not deformed by the suction.

The pulp slurry 2 may be composed of pulp fibers and water, or in addition thereto, inorganic materials such as talc and kaolinite, inorganic fibers such as glass fibers and carbon fibers, synthetic resin powders such as polyolefin and the like. Components such as fibers, non-wood or vegetable fibers, and polysaccharides may be contained. The compounding amount of these components is 1 to 70% by weight, especially 5 to
Preferably it is 50% by weight. 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 0.1 mm or more and 10 mm or less, respectively.
It is preferable that it is not less than mm and not more than 0.05 mm.

When a pulp layer having a predetermined thickness is formed, the papermaking mold 1 is pulled out of the pulp slurry as shown in FIG.
The moisture content is set to a predetermined value. Pulp layer 4 after suction dehydration
Has a water content of 60 to 95% by weight, particularly 60 to 80% by weight.
Is preferable in that the pulp layer 4 can be sufficiently held on the surface of the papermaking mold 1 by suction, and that the papermaking mold 1 can be transported without falling off the held pulp layer 4.

When the pulp layer 4 can be sucked and dehydrated to a predetermined moisture content, as shown in FIG. 2 (c), the papermaking mold 1 on which the pulp layer 4 is formed is shaped into a shape corresponding to the outer shape of the molded article to be molded. Is inserted into the concave portion 5a of the female mold 5 having the open concave portion 5a, and the pulp layer 4 is subjected to pressure dehydration, shape imparting, and heat drying in the concave portion 5a. In this embodiment, the female mold 5 is 1
Composed of two members, the shape of the molded object to be molded (for example, a complex shape or a shape with an undercut)
May be combined to form a female mold. The female mold 5 is previously heated to a predetermined temperature by a heating means 5b such as an electric heater.

The concave portion 5a of the female mold 5 is provided with
Covered by The sheet 7 is fixed at a peripheral portion 5c of the concave portion 5a by a predetermined means. The fixing portion may be the entire area of the peripheral portion 5c, or may be two or more opposing portions of the peripheral portion 5c.
The constituent material of the sheet 7 is not particularly limited as long as it has a predetermined elasticity. For example, as the sheet 7, a knitted fabric, a woven fabric, a nonwoven fabric, or the like can be used from the viewpoint of fluid permeability, and a knitted fabric is preferably used because it has sufficient elasticity.

The degree of elasticity of the sheet 7 is 10% or 2%.
The value of 0% elongation stress is 500 to 5000 Pa, especially 500
To 1000 Pa, the pulp layer 4 is not damaged when the papermaking mold 1 is inserted into the recess 5a, and when the papermaking mold 1 is taken out from the recess 5a, the molded product is removed from the recess 5a.
It is preferable because it can be easily released from the mold.

On the inner surface of the recess 5a of the female mold 5, a pulp layer 4
There is no vent hole for discharging water or water vapor generated from the water, and the inner surface is smooth. Therefore, by using a smooth or fine mesh as the sheet 7, the surface of the molded article becomes extremely smooth, and the appearance of the molded article becomes very good.

As shown in FIG. 2D, the papermaking mold 1 is inserted into the recess 5a while extending and deforming the sheet 7.
As described above, since the height of the core 10 in the papermaking mold 1 is made larger than the height (depth) of the molded body, when the papermaking mold 1 is further pushed into the concave portion 5a, the bottom of the pulp layer 4 becomes It first contacts the bottom of the recess 5a. Then Figure 2
As shown in (e), the papermaking mold 1 is further pushed and pressed. Due to this pressing, the core 10 in the papermaking mold 1 is pressed and deformed so as to follow the shape of the concave portion 5a of the female mold 5 and expands, thereby completely filling the space of the concave portion 5a. As a result, the pulp layer 4 formed on the surface of the papermaking mold 1 is further dewatered under pressure, and the inner surface shape of the concave portion 5a is transferred to the pulp layer 4.

While maintaining the pressed state of the papermaking mold 1, the papermaking mold 1
Is sucked at the suction pipe. As described above, the flow path in the fluid-permeable material 20 disposed on the outer surface of the papermaking mold 1 allows the fluid to flow without being crushed even under the pressed state of the papermaking mold 1. The contained water is discharged out of the papermaking mold 1 through the flow passage and the fluid communication passage 12 formed in the core 10. Water vapor generated by drying the pulp layer 4 is also discharged out of the papermaking mold 1 through the same route.

The pressed state of the papermaking mold 1 is maintained for a predetermined time, and the pulp layer 4 is dried to obtain a pulp molded article 6 as an object. Next, as shown in FIG. 2F, the pressing of the papermaking mold 1 is stopped. Thus, the core 10 of the papermaking mold 1
Returns to the shape before pressing, and the obtained pulp molded article 6 is released from the side surface of the papermaking mold 1. Further, the papermaking mold 1 is sucked from the outer surface to the inside through the suction pipe 42, and the papermaking mold 1 is pulled up while the molded body 6 is adsorbed on the bottom surface of the papermaking mold 1. As the papermaking mold 1 is pulled up, the stretched sheet 7 contracts, and the molded body 6
The mold is spontaneously released from the mold a, and is easily taken out from the female mold 5.

According to the present embodiment, the pulp molded article 6 shaped and formed in the recess 5a of the female mold 5 can be released from the recess 5a extremely easily, so that the production efficiency can be improved. Is significantly improved. Further, it is possible to effectively prevent the pulp molded article 6 from being damaged when the mold is released. Further, by using a smooth or fine mesh as the sheet 7, the pulp molded product 6
And the surface of the molded body 6 becomes extremely good.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a diagram corresponding to FIG. 2E in the first embodiment. In the second embodiment, only the points different from the first embodiment will be described.
For the same points as in the first embodiment, the description in detail regarding the first embodiment is appropriately applied. In FIG. 3, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals.

In the present embodiment, the female mold 5 has a hollow portion 5d inside, and a vent hole 5e for discharging water and water vapor generated from the pulp layer 4 in the inner surface of the concave portion 5a.
Are used. On the outer surface of the female mold 5, an exhaust hole 5f communicating with the hollow portion 5d is provided. As a result, in the female mold 5, the vent hole 5 e, the hollow portion 5 d, and the exhaust hole 5 f communicate with each other, and a communication path from the inner surface of the concave portion 5 a to the outside of the female mold 5 is formed.

Further, in the present embodiment, the flow path of the fluid is formed in the stretchable sheet 7 in the thickness direction, similarly to the fluid-permeable material 20 arranged on the outer surface of the papermaking mold 1. In this way, the flow path allows the fluid to flow without being crushed even when the papermaking mold 1 is pressed. Therefore, the material of the sheet 7 in the present embodiment can be the same as the material of the fluid-permeable material 20.

In the pressure dehydration, shape imparting, and heat drying of the pulp layer 4 in the present embodiment, as shown in FIG.
Through the flow passage (vent hole 5) formed in the female mold 5
e, the air is discharged to the outside of the female mold 5 through a communication passage communicating with the hollow portion 5d and the exhaust hole 5f). In this case, heating air may be supplied into the core 10 through the suction pipe 42 in the papermaking mold 1 to further promote the heating and drying of the pulp layer 4.

In the present embodiment, similarly to the first embodiment, the molded body 6 can be easily released from the mold.

The present invention is not limited to the above embodiments.
For example, each of the above embodiments relates to the production of a box-shaped molded article having an opening, but the production method of the present invention is applied to the production of molded articles of various shapes, for example, caps, spoons, lids, and the like. You can also.

[0034]

According to the method for producing a pulp molded article of the present invention, the molded article can be produced with good releasability and high production efficiency. Further, according to the method for producing a pulp molded article of the present invention, the molded article is effectively prevented from being damaged at the time of mold release.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a papermaking mold used in a first embodiment of a method for producing a pulp molded article of the present invention.

FIG. 2 is a process diagram schematically showing each process in the first embodiment of the method for producing a pulp molded article of the present invention.

FIG. 3 is a view showing a step of pressing a papermaking mold in a second embodiment of the method for producing a pulp molded article of the present invention [FIG.
(E) equivalent diagram].

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 papermaking mold 2 pulp slurry 4 pulp layer 5 female mold 5 a recess 6 pulp molded product 7 elastic sheet 10 core 20 fluid permeable material

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) D21J 3/00-3/12

Claims (5)

(57) [Claims] 1. An elastically deformable papermaking mold having a communication passage communicating from the outside to the inside is immersed in a pulp slurry,
Moisture in the pulp slurry is sucked from the outside to the inside of the papermaking mold through the communication passage to form a pulp layer on the surface of the papermaking mold, and then has a concave portion having a shape corresponding to the outer shape of the molded article. A stretchable sheet is formed by extending the stretchable sheet through the papermaking mold having the pulp layer formed in the female mold recess in which the stretchable sheet is fixed at the periphery of the recess and covers the upper surface of the recess. Insert while deforming, so that the bottom of the pulp layer is in contact with the bottom of the recess through the stretchable sheet, and further press-deform the papermaking mold to follow the shape of the recess, A method for producing a pulp molded article, wherein the shape of the recess is transferred to a pulp layer to form a molded article. 2. The method for producing a pulp molded article according to claim 1, wherein the papermaking mold is deformed while the female mold is heated to a predetermined temperature. 3. The papermaking mold has, on its surface, a fluid-permeable material capable of forming a fluid flow passage in the thickness direction even during the deformation of the papermaking mold. Sometimes, the moisture in the pulp layer,
The method for producing a pulp molded article according to claim 1 or 2, wherein the pulp molded article is discharged outside the papermaking mold through the flow passage. 4. The pulp layer according to claim 1, wherein the stretchable sheet has fluid permeability, and the recess has a fluid communication passage communicating with the outside of the female mold. The moisture inside,
The method for producing a pulp molded article according to claim 1, wherein the pulp molded article is discharged to the outside of the female mold through the flow path through the stretchable sheet. 5. It has a communication passage communicating from outside to inside.
Elastically deformable papermaking mold and a shape corresponding to the outer shape of the molded body
A stretchable sheet having a concave shape and a peripheral portion of the concave portion
A female mold that is fixed at and covers the upper surface of the concave portion,
Pulp molding wherein the sheet has fluid permeability
Body manufacturing equipment.