JP2007291600A - Molded pulp product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molded pulp product which is thin and lightweight, and is excellent in a heat-insulating property. <P>SOLUTION: This molded pulp product is characterized by having a pulp fiber layer of single layer structure made from a single raw material composition and having a density distribution in the thickness direction and having a coating layer on at least inside or outside of the pulp fiber layer. It is preferable to have a density distribution changing from a small density to a large density or from a large density to a small density in the density direction in the pulp fiber layer. It is also preferable that the outside of the pulp fiber layer is covered with a pulp fiber layer different from the pulp fiber layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pulp mold molded body and a method and apparatus for producing a pulp mold molded body, and more particularly to a pulp mold molded body that is thin, lightweight, and excellent in heat insulation performance, and a method and apparatus for manufacturing the same.

As a prior art regarding a heat insulating container made of pulp mold, for example, a technique described in Patent Document 1 is known.
This technique relates to a heat insulating double container including a container main body and an outer layer container disposed with a predetermined gap on the outside thereof.

  In such a heat insulating container, an outer layer container must be provided outside the container body in order to provide heat insulation. Accordingly, the thickness of the entire container is increased. Further, since the container has a double structure, there is a limit to reducing the weight of the container.

Japanese Patent Laid-Open No. 11-301753

  The present invention provides a novel pulp mold molded article that is thin, lightweight, and excellent in heat insulation performance, and a production method and apparatus for efficiently producing the pulp mold molded article.

  The pulp molded article of the present invention comprises a pulp fiber layer having a single layer structure which is made from a single raw material composition and has a density distribution in the thickness direction.

  The present invention includes a paper making / dehydration step for making a pulp fiber layer from a single raw material composition and dehydrating it, and placing the dehydrated pulp fiber layer in a drying mold to provide a density distribution in the thickness direction of the pulp fiber layer. It is related with the manufacturing method of the pulp mold molded object which comprises the drying process dried while providing. Specifically, an exhaust hole communicating with the outside corresponding to the portion of the pulp fiber layer not imparting density distribution is formed on the inner surface of the dry mold, and the inside of the dry mold is forcibly exhausted through the exhaust hole. While pressing the pulp fiber layer against the inner surface of the dry mold with an elastically deformable core from the inside of the pulp fiber layer arranged in the dry mold, the pressing force by the core is reduced. The exhaust is stopped, the core is separated from the pulp fiber layer, and a density distribution is imparted in the thickness direction of the pulp fiber layer.

  Moreover, this invention relates to the manufacturing apparatus used for the manufacturing method of the pulp mold molded object of the said this invention. Specifically, it is elastically deformable by pressing the pulp fiber layer from the inside of the pulp fiber layer disposed in the drying mold to the inner surface of the drying mold. A pulp mold molded body manufacturing apparatus comprising: a core; and further, on the inner surface of the dry mold, an exhaust hole communicating with the outside corresponding to a portion of the pulp fiber layer not imparting density distribution is formed. .

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method and apparatus of the pulp mold molded object which can manufacture the pulp mold molded object which is thin, lightweight, and was excellent in the heat insulation performance, and this pulp mold molded object efficiently are provided. .

The present invention will be described below based on preferred embodiments with reference to the drawings.
FIG. 1 shows an embodiment of a pulp molded product of the present invention having a heat insulating container specification used for food containers such as instant cup noodles. In the figure, reference numeral 1 denotes a heat insulating container, 23 denotes hot water filling lines, and 24 denotes a stacking step.

  As shown in FIG. 1, in the heat insulating container 1, a cup-shaped container body 20 is formed by the pulp fiber layer 2. A flange portion 21 having a predetermined thickness is formed at the opening edge of the container, and the inner surface of the container body 20 (pulp fiber layer 2) and the flange portion 21 are covered with the coating layer 3.

  The pulp fiber layer 2 is made from a single slurry (raw material composition) described later, and has a density distribution in which the density of the pulp fiber layer 2 changes from small to large in the thickness direction from the inside to the outside. This is a single-layer structure in the body portion 22 of the present invention.

  In this specification, having a density distribution in the pulp fiber layer means that the size of the gap between the pulp fibers bound in the pulp fiber layer (void amount: empty volume) has a distribution in the thickness direction. The larger the gap, the smaller the density of the pulp fiber layer, and the smaller the gap, the higher the density. Therefore, if the size of the gap between the fibers is constant in the thickness direction, the pulp fiber layer does not have the density distribution.

  The density in the pulp fiber layer 2 is preferably continuously changing from the viewpoint of obtaining high strength, and is preferably discontinuously changing stepwise from the viewpoint of obtaining high heat insulating properties. .

  The thickness of the body portion 22 having the density distribution is preferably 0.5 to 3.0 mm, and more preferably 0.5 to 2.0 mm in view of container strength, heat insulation, and weight reduction of the container. If it is less than 0.5 mm, strength and heat insulating properties required for a cup noodle container cannot be obtained, and if it exceeds 3.0 mm, it is too heavy for a cup noodle container.

The bulk density of the body 22 having the density distribution (bulk density after drying) is preferably from 0.1 to 0.6 g / cm ^3, more preferably 0.2-0.5 g / cm ^3. If it is less than 0.1 g / cm ³ , the strength required for a cup noodle container cannot be obtained, and if it exceeds 0.6 g / cm ³ , the heat insulation becomes insufficient, and it becomes difficult to hold a container containing hot water with bare hands. . In addition, it is preferable that the density of the bottom in the case of forming the bottom having a density distribution is the same bulk density as that of the body.

The bulk density (bulk density after drying) of the part other than the body part 22 is preferably 0.2 to 0.9 g / cm ³ , and in particular, the density of the part requiring strength is 0.3 to 0.9 g. preferably a / cm ^3.

  The pulp fiber layer 2 is preferably formed only of pulp fibers. As the pulp fiber, wood pulp such as virgin pulp and waste paper pulp, non-wood pulp such as cotton pulp, linter pulp, bamboo and straw, etc., or imparting hydrophobicity by applying mercerization and / or crosslinking to these pulps Pulp fibers. In particular, as the pulp fiber imparted with hydrophobicity, “HBA-LA”, “HBA-S”, “HBA-FF”, etc. manufactured by Wafer User Co., USA are preferably used. Two or more kinds of these pulp fibers can be mixed and used at an appropriate ratio.

  It is more preferable that the pulp fiber layer 2 contains a bulking agent in order to improve the heat insulation and surface properties in addition to the pulp fiber. Examples of the bulking agent include an anionic surfactant, a cationic surfactant, a nonionic surfactant, and an amphoteric surfactant. These bulking agents may be used alone or in combination. In particular, “KB-115” and “KB-08W” manufactured by Kao Corporation are preferably used as bulking agents that improve heat insulation.

  In addition to the bulking agent, the pulp fiber layer 2 can contain additives such as pigments, fixing agents, fungicides, and sizing agents.

  The coating layer 3 imparts functions such as waterproofness, oil resistance, and gas barrier properties to the heat insulating container 1. The thickness of the coating layer 3 can be set according to these functions. The covering layer 3 can be formed by laminating resin films.

  Examples of the resin film used for the coating layer 3 include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate, polyamide resins such as nylon, polyvinyl resins such as polyvinyl chloride, and polystyrene. Examples thereof include thermoplastic resin films such as styrene resins, and biodegradable resin films such as modified polyethylene terephthalate and aliphatic polyester. In view of manufacturing cost, moldability and the like, polyolefin resin is preferable, and biodegradable resin film is preferable from the viewpoint of environmentally friendly disposal. The coating layer may be formed by laminating two or more of these resin films.

Next, the case where the preferable manufacturing apparatus of the pulp mold molded body of this invention is applied to the manufacturing apparatus of the container main body 20 of the heat insulation container 1 is demonstrated, referring FIG.
FIG. 2 shows an embodiment in which the apparatus for producing a pulp molded product of the present invention is applied to the production of a food insulated container such as instant cup noodles. In the figure, reference numeral 10 denotes a manufacturing apparatus.

  The manufacturing apparatus 10 includes a drying mold 11 in which the pulp fiber layer 2 is disposed, and an elastically deformable core 16 that presses against the cavity forming surface of the drying mold 11 from the inside of the pulp fiber layer 2.

  The drying mold 11 includes a pair of split molds 12 and 12, and by combining these split molds 12 and 12, a cavity 110 corresponding to the outer shape of the container body 20 is formed.

Exhaust holes 13 communicating with the outside are formed in the inner surface of the drying mold 11 so as to correspond to the portion of the pulp fiber layer 2 that does not impart density distribution.
In the present embodiment, the portion of the cavity forming surface of the drying mold 11 corresponding to the body portion 22 of the container body 20 has no steam exhaust hole, and the flange portion 21 and bottom (bottom surface) of the container body 20 on the cavity forming surface. And a portion corresponding to the portion (including a portion rising from the bottom surface) is provided with a steam exhaust hole 13 leading to the outside.

The shape of each of the exhaust holes is preferably a slit shape from the viewpoint of surface smoothness, exhaust efficiency, and prevention of clogging of the exhaust holes. The width of the exhaust hole (slit width) is preferably 0.1 to 0.5 mm, and more preferably 0.1 to 0.3 mm. The total opening area of the exhaust hole, in the present embodiment, the container strength, preferably 100～1500Mm ² from the viewpoint of stain prevention, 200 to 1000 mm ² and more preferably. In the case where the molded body to be manufactured has a portion where an edge such as a corner or ridge line is to be clearly formed, it is preferable that the exhaust hole 13 is opened at the portion where the edge such as the corner or the like is desired to be provided.
The exhaust hole 13 is connected to an exhaust line 130 having an open / close valve 131, and an end of the exhaust line 130 is connected to a negative pressure source (not shown).

  The drying mold 11 includes a lid 15 that closes the upper opening 111, and the lid 15 has a hole 14 that communicates with the opening 111 and allows the core 16 to be taken in and out. A heating means 120 is attached to each split mold 12 constituting the drying mold 11.

  The core 16 has elasticity, is freely expandable and contractable, and has a bag shape. Examples of the material of the core 16 include urethane, fluorine rubber, silicone rubber, elastomer, and the like excellent in tensile strength, impact resilience, stretchability, and the like. The core 16 is provided with a pipe line 17 for supplying pressurized fluid into the core 16, and an open / close valve 18 is provided in the pipe line 17. A switchable negative pressure source and a pressurization source (not shown) are connected to the end of the pipe line 17.

Next, the preferable manufacturing method of the pulp mold molded object of this invention is demonstrated based on the manufacturing method of the said heat insulation container 1. FIG.
The manufacturing method of the heat insulating container 1 includes a paper making / dehydrating process of the pulp fiber layer 2 forming the container body 20, a drying process of drying the dehydrated pulp fiber layer 2, and a forming process of the coating layer 3. ing.

  In the paper making / dehydration process of the pulp fiber layer 2, first, the pulp fiber layer 2 having a single layer structure is made from a single slurry (single raw material composition). In this papermaking process, a papermaking mold is used in which a cavity having a predetermined shape corresponding to the container body 2 is formed by combining the split molds of a pair of split molds. An opening is formed above the cavity.

Each split mold constituting the papermaking mold is formed with a plurality of communication passages communicating the cavity with the outside. Each communication path is connected to suction means (not shown) such as a suction pump.
The total open area ratio of the communication passages on the inner surface (cavity forming surface) of the split mold is preferably 4 to 20%, more preferably 3 to 50% from the viewpoints of shortening drainage time and moldability.
Moreover, it is preferable that the drainage groove | channel which leads to each communicating path is formed in the cavity formation surface. The total opening area ratio of the drainage grooves on the cavity forming surface is preferably 50 to 90%, more preferably 60 to 80% from the viewpoint of preventing deformation of the papermaking net, moldability, drainage, and prevention of clogging of the papermaking net. Further, the width of the drainage groove is preferably 1 to 10 mm, more preferably 2 to 5 mm from the viewpoint of preventing deformation of the papermaking net, formability, drainage, and prevention of clogging of the papermaking net. The drainage grooves are preferably formed in a lattice shape so as to connect the communication paths.

The inner surface of each split mold is covered with a predetermined papermaking net. The papermaking net may be a single net or a combination of nets made of natural fibers, synthetic fibers or metal fibers. Among the materials described above, synthetic fibers are preferable from the viewpoint of easy formation of a net and durability. Examples of the natural fibers include plant fibers and animal fibers. Moreover, as said synthetic fiber, the synthetic resin fiber which consists of a thermoplastic resin, a thermosetting resin, and a semi-synthetic resin is mentioned. Examples of the metal fiber include stainless steel fiber and copper fiber. The papermaking net is preferably modified on the fiber surface in order to improve the slipperiness and durability of the net.
In consideration of the moldability and durability of the manufactured papermaking, the passage of solid components in the slurry and prevention of clogging, the wire diameter of the papermaking net is preferably 0.05 to 1.0 mm, more preferably 0.05. The mesh spacing of the net is preferably 0.15 to 2.0 mm, more preferably 0.15 to 1.5 mm.

A predetermined amount of slurry is pressurized and injected into the cavity, and the inside of the cavity is sucked under reduced pressure by a suction pump through the drainage groove and the communication path. Then, moisture in the slurry is removed by suction, and a pulp fiber layer is formed on the papermaking net that covers the formation surface of the cavity.
The injection pressure of the slurry into the cavity is preferably 0.05 to 1.0 MPa, more preferably 0.05 to 0.5 MPa from the viewpoint of shortening the slurry injection time and formability.
The pressure in the cavity through the reduced communication path is preferably 10 to 90 kPa, more preferably 20 to 70 kPa, from the viewpoint of shortening the dehydration time and moldability.

The single slurry used for making the pulp fiber layer 2 is preferably composed of only pulp fibers and water.
As the pulp fiber, wood pulp such as virgin pulp and waste paper pulp, non-wood pulp such as cotton pulp, linter pulp, bamboo and straw, etc., or imparting hydrophobicity by applying mercerization and / or crosslinking to these pulps Pulp fibers. In particular, pulp fibers imparted with the hydrophobic property are preferable, and “HBA-LA”, “HBA-S”, “HBA-FF”, etc., manufactured by Wafer User Co., USA are preferably used. These pulp fibers may be used alone or in admixture of two or more at an appropriate ratio.
The pulp fiber content in the slurry is preferably 0.05 to 10 wt%, more preferably 0.05 to 4 wt%.
Additives such as the above-mentioned bulking agent, sizing agent, pigment, fixing agent, and fungicidal agent can be added to the single slurry used for making the pulp fiber layer 2 at an appropriate ratio.

After pressurizing and injecting a predetermined amount of slurry into the cavity, pressure reduction in the cavity is continued through the communication path, and a pressurized fluid is supplied into the cavity to dehydrate the pulp fiber layer 2 made.
Air, steam, superheated steam, or the like is used as a pressurized fluid used for dehydration.
The pressure of the pressurized fluid during dehydration is preferably 0.05 to 1.0 MPa, more preferably 0.05 to 0.5 MPa, from the viewpoint of dehydration efficiency.

  The moisture content of the pulp fiber layer 2 after dehydration is preferably 50 to 85%, from the viewpoints of drying efficiency, surface smoothness and heat insulation of the container after drying, and prevention of scorching on the container surface after drying, and 60 to 80%. % Is more preferable.

  After the pulp fiber layer 2 is dehydrated to a predetermined moisture content, the pulp fiber layer 2 is separated from the cavity forming surface. Then, the undried pulp fiber layer 2 is transferred into the dry mold 11.

  When the container body 20 having the flange portion 21 is formed as in the present embodiment, no steam exhaust hole is provided on the cavity forming surface of the drying mold 11 corresponding to the body portion 22 of the container body 20. The cavity forming surface corresponding to the flange portion 21 and the bottom portion (including the bottom surface and the portion rising from the bottom surface) of the container body 20 is provided with a steam exhaust hole 13 leading to the outside. As shown in FIG. 3 (b), after the pulp fiber layer 2 is set in the drying mold 11 and the upper opening 111 of the drying mold 11 is closed with a lid 15 having an insertion hole 14, the drying mold 11 Is heated to a predetermined temperature by the heating means 120.

  The temperature of the drying mold 11 (mold temperature) is preferably 150 to 300 ° C, more preferably 170 to 250 ° C, from the viewpoint of preventing the occurrence of scorching of the pulp fiber layer 2 and improving the drying efficiency.

  While the pulp fiber layer is heated with the dry mold, the core 16 is inserted into the cavity 110 of the dry mold 11 through the insertion hole 14 of the lid 15 as shown in FIG. Seal. Then, a pressurized fluid is supplied into the core 16 and the core 16 is expanded in the cavity 110, whereby the pulp fiber layer 2 is pressed against the cavity forming surface and heated and dried.

  The pressing force of the core 16 at the time of heating and drying is preferably 0.05 to 1.0 MPa, more preferably 0.1 to 0.3 MPa from the viewpoints of heat insulation, drying efficiency, and surface smoothness.

  During the heating and drying, the steam generated from the pulp fiber layer 2 is forcibly exhausted through the exhaust hole 13. As a result, in the portion of the pulp fiber layer 2 corresponding to the portion where the exhaust holes are not formed, the moisture remaining between the fibers is partially vaporized before reaching the exhaust holes to widen the gap between the fibers. 2 is reduced in density inside. On the other hand, since the vaporized water is immediately exhausted from the exhaust hole at the portion where the exhaust hole 13 corresponding to the opening and bottom of the container body 20 is formed, the pulp layer 2 is kept compressed by the pressing force of the core. Densification progresses.

  The pressure of the above-described forced exhaust is preferably 4 to 60 kPa, more preferably 4 to 10 kPa, from the viewpoint of drying efficiency and increase in bulk of the container.

  When the pulp fiber layer 2 is sufficiently dried, as shown in FIG. 3C, the pressurized fluid is removed from the core 16 to reduce the core 16, and the inside of the cavity 110 is decompressed while the exhaust hole Stop forced exhaust through 13.

  The step of pressurizing the pulp fiber layer 2 with the core 16 while performing forced exhaust and the step of contracting the core 16 by stopping the forced exhaust can be repeatedly performed as necessary.

  And after sufficient density distribution is provided to the trunk | drum 22 of the container main body 20, as shown in FIG.3 (d), the split molds 12 and 12 are opened, the container main body 20 is taken out, and a container main body is needed as needed. Trimming etc.

In the step of forming the covering layer 3, the inner surface of the container body 20 (pulp fiber layer 2) and the flange portion 21 are covered with the covering layer 3.
In order to form the coating layer 3 with the resin film, a known method such as pressure forming or vacuum forming can be used.

  In the case of vacuum forming, for example, as shown in FIGS. 4A and 4B, a coating layer can be formed using a plug 6 provided with a vacuum forming die 5 and a heater 60. The vacuum forming 5 has substantially the same dimensions as the drying mold 10 used in the drying process of the pulp fiber layer 2, has a lattice-shaped ventilation groove 51 on the cavity forming surface 50, and is provided outside from the ventilation groove 51. A vacuum suction path 52 is provided. The container main body 20 is set in the vacuum mold 5, and a resin film 30 that has been heated and softened in advance so as to close the opening of the container main body 20 is set in the opening. Then, while the plug 6 is brought into contact with the resin film 30 from above and the resin film 30 is pushed into the container body 20, the container is made through the ventilation groove 51 and the vacuum suction path 52 using the air permeability of the container body 20. The inside of the main body 20 is depressurized, and the resin film 30 is attached so as to cover the inner surface of the container main body 20 and the flange portion 21. And the excess resin film 30 is removed and manufacture of the heat insulation container 1 is completed.

  Thus, since the container main body 20 is formed of the pulp fiber layer 2 having a single structure having a density distribution that changes from a low density to a high density from the inside toward the outside in the thickness direction, the container body 20 is thin. It is lightweight and excellent in heat insulation, and a desired strength can be obtained outside the container body. In addition, since a foaming agent is not used for reducing the density, an excellent heat-insulating container corresponding to environmental conservation can be obtained by using a biodegradable material for the pulp fiber layer and the coating layer. Furthermore, there is no joint in the trunk | drum 22 and a bottom part, the flange part 21, the trunk | drum 22 and the bottom part are integrally formed, and it is excellent also in mechanical strength (compression strength, tolerance). In addition, since the outer surface of the pulp fiber layer 2 has a high density and a smooth surface, the printing characteristics are also excellent.

  Since the container body 20 is composed of the pulp fiber layer 2 formed by papermaking only once with a single slurry, the manufacturing process of the heat insulating container 1 is simplified and shortened as compared with the conventional method. Therefore, the production efficiency of the heat insulating container 1 is greatly improved by the conventional method.

  This invention is not limited to the heat insulation container 1 of the said embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably.

In the case of the heat insulating container 1 as in the above embodiment, the pulp mold molded body of the present invention preferably has the density distribution in the pulp fiber layer in the body portion of the container body. The site | part which has can be set according to the use, shape, etc. of a pulp mold molded object.
Moreover, when heat insulation is required for the entire container, such as a bowl shape, a tray shape, etc., the density distribution can be provided in the entire pulp fiber layer.

  The pulp mold molded body of the present invention is a single-layered pulp fiber having a density distribution that changes from a small density to a large density from the inside to the outside in the thickness direction, like the heat insulating container 1 of the above embodiment. Preferably it comprises a layer. On the other hand, containers mainly intended to protect the contents, industrial members that have a sound absorbing function, etc. have a density distribution that changes from large to small in the thickness direction from the inside to the outside. A pulp fiber layer having a single layer structure may be provided.

  In the pulp mold molded body of the present invention, the flange portion 21 is preferably formed at the time of making the pulp fiber layer 2 as in the above embodiment, but the flange portion is formed by bending after the pulp fiber layer is made. You can also Further, the form of the flange portion is not limited to the form of curling outward with a predetermined curvature, and other forms may be used.

In the pulp mold product of the present invention, the coating layer 3 is preferably formed of a resin film as in the above-described embodiment, but the coating layer can also be formed by coating with a paint. Examples of the coating technique include coating the coating and immersing the container body 2 in the coating.
Moreover, the pulp mold molded body of the present invention achieves further improvements in printability, strength, water resistance, etc. by coating the outer surface with another pulp fiber layer having a high density equal to or higher than the density of the fiber layer 2. Can do.

  The pulp mold product of the present invention is preferably manufactured by papermaking a pulp fiber layer using a papermaking mold in which a predetermined cavity is formed by combining a pair of split molds as in the above embodiment. Depending on the shape of the molded pulp mold, it is not necessary to use a split mold. Other papermaking methods can also be used. For example, a male mold having a convex shape corresponding to the outer shape of the container body and having a large number of fluid flow holes opened on the outer surface thereof, and a predetermined papermaking net covering the papermaking portion. The pulp fiber layer may be formed by dipping in the slurry and sucking the slurry through the fluid circulation hole to make pulp fibers on the surface of the paper making net. The male material may be a rigid body or an elastic body.

Moreover, even if the shape of the pulp fiber layer 2 is complicated, the pulp mold molded body of the present invention heats and dries the pulp fiber layer 2 using a hollow core because the pulp fiber layer can be pressed uniformly. However, a solid core may be used for heating and drying the pulp fiber layer 2.
The pulp mold molded body of the present invention comprises a heated male mold having a certain clearance from the female mold after the pulp fiber layer is arranged on a female mold having a shape corresponding to the outer shape of the pulverized pulp fiber layer. It can also be formed by drying the pulp fiber layer in combination with the female mold.
Furthermore, the pulp mold molded body of the present invention is a wet pulp fiber layer formed by forming a high density pulp molded body (another pulp fiber layer) previously dried in a female mold and making the pulp molded body. Can be formed by combining a heated male mold having a certain clearance with the female mold and drying the combined product. By adopting such a drying method, the wet pulp fiber layer is spread and involved by the steam generated from the wet pulp fiber layer, so that the outer side is covered with the dense pulp fiber layer. A pulp mold product having a density distribution that changes from a small density to a large density from the outside to the inside can be obtained. This molded product is very excellent in printability, strength, and water resistance, and also has excellent surface properties on the inside. In addition, the said another pulp fiber layer which concerns on this invention can be formed with a normal papermaking method using the fiber used for manufacture of the said pulp fiber layer 2. FIG.

  The pulp mold molded body of the present invention is particularly suitable for a heat insulating container having a flange portion as in the above embodiment, but the application target of the molded body of the present invention is not limited to this, for example, The present invention can also be applied to various shapes of containers such as bowl-shaped containers, bottle-shaped containers, and tray containers, hollow molded bodies such as cylindrical molded bodies, and flat molded bodies.

Hereinafter, the present invention will be described more specifically with reference to examples.
A heat insulating container was produced according to the description in Example 1 and Comparative Example 1, and each performance evaluation of the container was performed. The evaluation results are shown in Table 1.

[Example 1]
<Container body dimensions>
Height H: 106mm
Opening inner diameter φ1: 90mm
Bottom profile φ2: 68.5mm
Flange part maximum outer diameter φ3: 96mm
Flange thickness T: 3mm
Body thickness T22: 1.4mm
Bottom thickness T25: 1.2mm

  A pulp fiber layer was made under the following conditions using the following paper making mold provided with a pair of split molds in which cavities corresponding to the container bodies of the above dimensions and shapes were formed.

<Making paper>
Material: total open area of the aluminum communication passage: 1287mm ² (torso portion corresponding to the bottom: .phi.3 × 54 pieces = 382mm ^2, portions corresponding to the flange portion outer peripheral: entire circumference at 3mm wide slit shape = 905mm ²⁾
Total opening area of drainage grooves (lattice): 25071 mm ²
Drainage groove width: 3mm
Total open area ratio of drainage groove on cavity forming surface: 75%
Papermaking net: Double papermaking net consisting of 20 mesh PET net and 80 mesh PET net

<Slurry composition>
Pulp slurry concentration: 0.1% by weight
Pulp fiber: Cross-linked pulp ("HBA-LF" 50% by weight manufactured by Wafer User, Inc. + Bleach Craft Pulp (BKP) 50% by weight)
Bulking agent: “KB115” manufactured by Kao Corporation (5% by weight of pulp fiber)
Sizing agent: “AS262” manufactured by Japan PMC (2% by weight of pulp fiber)

<Making conditions>
Slurry supply amount: 15 liters (only once)
Slurry supply pressure: 0.2 MPa
Cavity suction pressure: 0.06 MPa

A pressurized fluid was supplied into the cavity under the following conditions and dehydrated until the water content became 75%.
<Dehydration conditions>
Pressurized fluid: compressed air, pressing force: 0.2 MPa (15 seconds)
Cavity suction pressure: 0.06 MPa

Prepare a drying mold having the following exhaust holes in the portions corresponding to the outer periphery and bottom of the flange body of the container body to be manufactured (the bottom surface and the rising portion from the bottom surface), arrange a pulp fiber layer in the drying mold, and exhaust holes The pulp fiber layer is pressurized with the following core while forcibly exhausting through. Thereafter, forced evacuation was stopped and the core was contracted to produce a container body.
<Dry type>
Material: Aluminum Slit width of each exhaust hole: 0.15mm
Portions corresponding to the flange portion: 4 on the outer periphery of the flange portion at a pitch of 3 mm vertically (one of which opens at the portion corresponding to the corner portion formed by the outer peripheral surface and the lower surface of the flange portion)
Parts corresponding to the bottom: 4 at 5mm pitch on the bottom (one split mold), 5 vertically at the 3mm pitch on the entire circumference of the rising part from the bottom Total area of the exhaust holes on the cavity forming surface: 396mm ²
Total opening area ratio of all exhaust holes on the cavity forming surface: 1.2%
<Core>
Material: Silicone rubber Pressurized fluid: Compressed air <Drying conditions>
Mold temperature: 200 ℃
Core pressing force: 0.2 MPa (15 seconds)
Forced exhaust pressure: 5kPa

<Formation of coating layer>
A coating layer was formed on the obtained container body under the following conditions to produce a heat insulating container.
Resin film: Polyethylene (LDPE / HDPE bilayer structure)
Resin film thickness: 150 μm
Vacuum forming machine: Sanwa Kogyo brand name PLAVAC-FE36PHS
Film heating method: Infrared heater (110mm distance between heater and resin film)
Film heating temperature: 255 ° C. (former display temperature)
Film heating time: 35 seconds Plug dimensions: 60mm diameter x 127mm length
Plug material: Aluminum (surface is processed with Teflon (registered trademark))
Plug temperature: 110 ° C (plug actual surface temperature)
Vacuum forming mold: Mouth hole diameter φ89.8mm, bottom diameter φ68.5mm, height 93.5mm
Mold temperature for vacuum forming: 100 ° C (actual surface temperature inside the mold)
Molding time: 8 seconds

[Comparative Example 1]
Heat insulation similar to that of Example 1 except that a dry mold in which exhaust holes (width 0.15 mm, approximately the entire circumference of the barrel, 10 mm vertically) are formed in the portion corresponding to the barrel of the container body A container was prepared.

[Density evaluation]
Each site | part of the obtained container main body was cut out, and the bulk density was measured from the apparent volume and weight.

[Evaluation of density distribution]
Using an electrolytic emission scanning electron microscope (“S-4000 type” manufactured by Hitachi, Ltd.), each part of the obtained container was observed at a magnification of 50 times to determine the presence or absence of a density distribution.

[Weight evaluation]
The obtained container was dried in a low-humidity room at 100 ° C. for 1 hour, and the weight after drying was measured.

(Insulation property evaluation)
A thermocouple was attached to the outside of the body of the obtained container, hot water at 80 ° C. was poured into the container, and the temperature outside the body of the container after 3 minutes from the injection was measured. In addition, it was examined whether or not the container filled with hot water could be grasped by hand.
<Temperature measurement with thermocouple>
○: Less than 60 ° C. Δ: 60-65 ° C.
×: Over 65 ° C <Container grip test by hand>
○: Level that feels warm △: Level that feels a little hot but can be gripped ×: Level that feels hot and cannot be gripped

[Strength evaluation]
Using a compression tester (Orientec, Tensilon, “RTA-500”), the longitudinal compression strength and transverse compression strength of the obtained container were evaluated by the following methods.
<Vertical compressive strength>
The container was placed on a mounting table with the opening of the obtained container down, and the compressive strength of the container body when the presser was lowered from above the bottom of the container at a crosshead speed of 20 mm / min was determined. .
○: 25 kgf or more (strength required for packaging, transportation, and use)
X: Less than 25 kgf <lateral compression strength>
The obtained container is placed horizontally on a mounting table in which a groove for accommodating the flange portion is formed in a portion corresponding to the flange portion of the container, and the diameter is 10 mm at a crosshead speed of 20 mm / min from above the container body. The compressive strength of the container body when the presser of the round bar was lowered was determined. And the obtained intensity | strength was relatively evaluated with the value of the container made from a commercially available foaming styrene as follows.
<Evaluation>
○: Equal to or greater than foamed styrene container (strength that can be used during packaging, transportation, and use)
X: Below foamed styrene container

  As shown in Table 1, the heat insulating container of Example 1 is thinner and lighter than the heat insulating container of Comparative Example 1, has excellent heat insulating properties, and can be sufficiently used as a container for instant cup noodles. confirmed.

FIG. 1 is a half cross-sectional view of the pulp mold product of the present invention as a heat insulating container. FIG. 2 is a diagram schematically showing an embodiment of the apparatus for producing a pulp mold product of the present invention. 3A to 3D are diagrams schematically showing a drying process of a pulp fiber layer forming a container body in the heat insulating container. FIG. 3A shows a state in which the pulp fiber layer after papermaking is disposed in a drying mold. FIG. 3B shows a state in which the pulp fiber layer is pressed by the core in the dry type cavity. FIG. 3C shows a state where the core is contracted. FIG. 3 (d) shows the removed container body. 4 (a) and 4 (b) schematically show a process for forming a coating layer in the heat insulating container. FIG. 4A shows a state in which a resin film is laminated on the inner surface of the container body by vacuum forming. FIG.4 (b) is an expansion of the principal part about lamination | stacking of a resin film.

Explanation of symbols

1 Insulated container (pulp mold)
2 Pulp fiber layer 20 Container body 21 Flange 22 Body 3 Covering layer 10 Manufacturing device 11 Drying type 110 Cavity 111 Opening 12 Split mold 120 Heating means 13 Exhaust hole 130 Exhaust pipe 131 Open / close valve 14 Insertion hole 15 Lid 16 Child 17 pipeline

Claims (8)

  A pulp mold molded article comprising a pulp fiber layer having a single layer structure which is made from a single raw material composition and has a density distribution in the thickness direction, and at least an inner surface or an outer surface of the pulp fiber layer is coated with a coating layer.   The pulp mold molded body according to claim 1, wherein the pulp fiber layer has a density distribution that changes from a low density to a high density or from a high density to a low density in the thickness direction.   The pulp mold molded product according to claim 1, wherein an outer surface of the pulp fiber layer is covered with a pulp fiber layer different from the pulp fiber layer.   The pulp mold product according to claim 3, wherein the density of the other pulp fiber layer is equal to or higher than the maximum density of the pulp fiber layer.   The pulp mold molded body according to claim 1, wherein the pulp fiber layer and the coating layer are formed of a biodegradable material.   The pulp mold molded body according to claim 1, wherein a cup-shaped container main body is formed by the pulp fiber layer, and a flange portion is formed at an opening edge thereof.   The pulp mold product according to claim 6, wherein the density distribution is provided in a body portion of the container body.   The pulp mold product according to claim 6, wherein the flange portion and the bottom portion of the container body are formed at a higher density than the body portion.

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