JP3118708B2 - Pulp mold hollow molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulp molded hollow molded article using pulp as a main raw material.

[0002]

2. Description of the Related Art In general, plastic is used as a raw material for hollow containers such as containers and bottles having a lid, because of its excellent moldability and advantageous productivity. Have been. However, since a plastic hollow container has various problems in disposal treatment, a pulp hollow container is considered as an alternative. The hollow container made of pulp is economically excellent because it is easy to dispose and can be manufactured using waste paper as a raw material.

As a conventional technique relating to a hollow container made of pulp, for example, the one described in Japanese Patent Application Laid-Open No. 5-279998 is known. The container described in this publication has a rising angle of the side wall of 45 ° or more and a depth of 15 mm or more. However, since this container is manufactured by pressing a pulp component collected on a papermaking net with a pressing mold and further hot-pressing with a metal mold, the rising angle of the side wall is substantially vertical or not so. It is virtually impossible to make the above and make the bottom deep.

Accordingly, an object of the present invention is to provide a pulp molded hollow molded body having a large rising angle of a side wall and a deep bottom.

[0005]

Means for Solving the Problems The present invention has a bottom portion and the body portion, the angle between the outer surface of the side wall of the ground plane and the body portion of the bottom portion θ is 85 ° greater than the longitudinal section and / Or in cross section
The thickness T2 of the corner part is the thickness of the other part
The above object has been achieved by providing a pulp molded hollow molded body mainly composed of pulp, which is larger than T1 and whose body height is 50 mm or more.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a pulp mold hollow molded article of the present invention will be described based on preferred embodiments with reference to the drawings. 1 and 2 are a perspective view and a longitudinal sectional view of a pulp mold hollow molded body (hereinafter, simply referred to as a molded body) 1 of the present embodiment. The molded body 1 is a hollow container particularly suitable for accommodating contents such as a powdery body and a granular body, and has an opening 2 at an upper portion thereof, and further has a body 3 and a bottom 4.
have.

The body 3 and the bottom 4 are connected to each other via a curved surface 5, thereby increasing the impact strength of the molded body 1. The curvature of the curved surface portion 5 is 0.5 mm or more, especially 5 m
m or more is preferable from the viewpoints of improvement of impact strength, improvement of drying efficiency, improvement of surface finish of a molded article, and the like. The shape of the cross section of the molded body 1 is substantially the same over the height direction of the molded body 1, and has a rectangular shape with four rounded corners. This also increases the impact strength of the molded body 1. The curvature at the four corners is preferably 0.5 mm or more, particularly 5 mm or more for the same reason as in the case of the curved surface portion 5. In addition, each of the four sides of the rectangle has a gently curved shape slightly expanding outward. The body 3 is formed with a concave portion 6 that is continuous over the entire circumference thereof, thereby improving the gripping property of the molded body 1.

The outer surfaces of the front and rear walls constituting the body 3 are shaped so as to form a straight line in the height direction of the molded body 1 when the molded body 1 is viewed from the side. Except the concave portion 6). Similarly, the outer surfaces on the left and right sides forming the body 3 also have a shape that forms a straight line across the height direction of the molded body 1 when the molded body 1 is viewed from the front (similarly). Except the concave portion 6).

The bottom 4 is composed of a central recess 7 and a continuous heel 8 surrounding the central recess 7. The outer surface of the heel portion 8 is a ground contact portion of the molded body 1. When the bottom 4 has such a configuration, the mounting stability (so-called sitting) of the molded body 1 is improved.

The outer surface and inner surface of the molded body 1 are smooth. Thereby, for example, when a plastic layer or a coating layer is formed on the outer surface and / or the inner surface, the adhesiveness is improved, and printing on the outer surface can be performed easily and neatly. Further, the appearance impression is further improved.
In the present specification, “smooth” means that the center line average roughness (Ra) of the surface irregularities on the outer surface or inner surface of the molded product is 5%.
0 μm or less and the maximum height (Ry) is 500 μm or less.

In the molded body 1, as shown in FIG. 2, the angle θ between the ground plane B of the bottom 4 and the outer surface of the side wall of the body 3 is
Each of the front and rear walls and the left and right walls is more than 85 °, preferably 89 ° or more (in FIG. 2, the angle θ is approximately 90 °).
°), and the height h (see FIG. 2) of the trunk 3 is 50 mm or more, preferably 100 mm or more. Angle θ is
It may be more than 90 °. In the container described in JP-A-5-279998, it is practically impossible to increase the rising angle of the side wall and make the bottom deep, and there are various restrictions on the design of the container. According to the present invention, there is no such disadvantage. Note that the outer surface of the side wall of the trunk portion to be measured for the angle θ is a straight line extending in the height direction of the formed body 1 on the outer surface of the side wall when the formed body 1 is viewed from the front or side direction. The part that forms Therefore, when measuring the angle θ, the outer surface of the concave portion 6 formed in the body 3 is not a measurement target.

Particularly, unlike the conventional pulp mold hollow molded body, the molded body 1 of the present embodiment has a body portion 3 and a joint and a thick portion formed by laminating between the body portion 3 and the bottom portion 4. Does not exist. As a result, the strength of the molded body is increased and the container has a good appearance impression.

The molded body 1 is formed using pulp as a main raw material. Of course, it may be formed from 100% pulp. When another material is used in addition to the pulp, the amount of the other material is preferably 1 to 70% by weight, particularly preferably 5 to 50% by weight. Other materials include inorganic substances such as talc and kaolinite, inorganic fibers such as glass fiber and carbon fiber, powder or fiber of synthetic resin such as polyolefin, non-wood or vegetable fiber, and polysaccharides.

In the molded body 1 formed from the above-described raw materials, the density (ie, the density of the meat portion of the molded body 1) is set to 0.1.
By setting the content to 4 to 2.0 g / cm ³ , mechanical properties such as tensile strength, compressive strength, drop strength and frontage strength of the molded body 1 are satisfied, and the molded body having appropriate rigidity as a hollow container can be obtained. can do. By setting the density of the molded body 1 to more preferably 0.6 to 1.5 g / cm ^3, the usability can be improved.

By setting the moisture permeability of the molded article 1 to 100 g / (m ² · 24 hr) or less, preferably 50 g / (m ² · 24 hr) or less based on JIS Z0208, moisture in the atmosphere is hardly absorbed. Thus, appropriate rigidity as a hollow container can be maintained, and the quality of the contents can be effectively prevented from being impaired by absorption of moisture, that is, the storage stability of the contents can be improved.

It is preferable that the molded article 1 has a tensile strength of 5 MPa or more, particularly 10 MPa or more, because breakage due to impact or the like can be suppressed. According to JIS P 8113, the tensile strength here is measured by cutting out a measuring piece having a length of 140 mm and a width of 15 mm from an arbitrary portion of the molded body 1 and mounting the same on a tensile testing machine at a distance between chucks of 100 mm and a tensile speed of 20 mm / Min means the breaking strength when pulled. However, in the case of a molded body from which a measurement piece of the above size cannot be obtained, measurement is performed by appropriately changing the size of the measurement piece.

The molded article 1 has a specific compressive strength of 10
0Nm^Two/ G or more, especially 110 Nm ^Two/ G or more
From the viewpoint that it is difficult to collapse even when the compacts 1 are stacked.
Good. The specific compressive strength referred to here is JIS P 812
This was measured by a method according to 6.

Further, the molded article 1 has a drop strength according to JIS.
When measured by a method according to Z 0217, it is preferable that the material has a strength that does not break even after falling 10 times.
Further, as a measurement of the frontage strength of the molded body 1, when the opening 2 of the molded body 1 is pressed from the side and deformed by 30 mm,
It is preferable that the pressing force is 10 N or more.

Furthermore, in the molded body 1, the thickness of the corner portion in the longitudinal section and / or the cross section thereof, much larger than the thickness of the portion other than that, whereby compared to the case both the thickness is the same compressive strength of the whole molded article 1 Te (buckling strength) improved. In longitudinal sectional view of the molded body 1 shown in FIG. 2, for example, a corner portion, i.e., the thickness T2 of the curved portion 5 is not larger than the thickness T1 of the body portion 3 (i.e., T2> T1 Der
). In this case, when T2 / T1 is 1.5 to 2, the compressive strength of the entire molded body 1 is further improved. Further, it is preferable that the thickness of T1 itself is 0.1 mm or more from the viewpoint that the minimum compressive strength required for the molded body 1 is exhibited. It is necessary that the molded body 1 has a predetermined compressive strength from the viewpoint of transportation of the molded body 1 and stacking of the molded body 1 in a warehouse or a store. Similarly, in the cross-sectional view of the body of the molded body 1 shown in FIG.
But not greater than the thickness T1 of the other part.

In addition to the above relationship between T1 and T2, if the density ρ2 of the corner portion in the longitudinal section and / or the cross section of the molded body 1 is smaller than the density ρ1 of the other portions. (That is, if ρ1> ρ2), the effect of simultaneously satisfying the trade-off phenomena of improving the compressive strength of the molded body 1 and reducing the amount of material to be used can be obtained. In this case, if 0.1 × ρ1 <ρ2 <ρ1, this effect becomes more prominent. In the compact 1 satisfying these relationships, the compressive strength is 190
N or more. The compressive strength is the maximum strength when the compact 1 is compressed at a speed of 20 mm / min from the height direction. In order to establish the above relationship between T1 and T2 and between ρ1 and ρ2, for example,
In the preferred manufacturing method, the pressure and flow rate of the pressurized fluid at the time of pressing by the core 16, the material and shape of the core 16, the shape of the molded body, and the like may be made appropriate.

As an example, T1 and T2 and ρ1 and ρ2 for the cross section of the trunk (see FIG. 4) are shown in Table 1 below.
The compressive strength of the molded body 1 manufactured to have the value shown in Table 2 is as shown in the table, and the compressive strength is improved as the value of T2 / T1 is larger and the value of ρ2 / ρ1 is smaller. I understand. In addition, Example 2 having a higher compressive strength is lighter in weight. T1, T2, ρ1, and ρ2 shown in the same table
Is the average of the values measured at four locations in the height direction of the trunk.

[0022]

[Table 1]

Next, a preferred method for producing the molded article of the present invention will be described with reference to FIG. 3, taking the production of the molded article 1 of the above embodiment as an example. The molded body 1 of the above embodiment is manufactured by a pulp molding method, and is particularly preferably manufactured by depositing pulp on the inner surface of a cavity of a mold having a cavity therein. 3 (a) to 3 (d) sequentially show a paper making step of the steps of manufacturing the molded body 1 by such a method. Specifically, FIG. 3 (a) shows a paper making step, and FIG. A core insertion step, (c) is a pressurization / dehydration step, and (d) is a step of opening a mold and taking out an intermediate of a molded body.

First, as shown in FIG. 3A, a pair of split dies 11 and 12 abut each other to form a cavity 13 having a shape corresponding to the outer shape of the molded body 1 to be molded. Pulp slurry. Each split mold 1
The 1,12, communicates with its outer surface and the cavity 13
A plurality of communicating holes 14 that causes, respectively. The inner surfaces of the split dies 11 and 12 are covered with nets (not shown) each having a mesh of a predetermined size.

Next, the inside of the cavity 13 is depressurized by sucking from the outside of the split dies 11 and 12, and the moisture in the pulp slurry is sucked and the pulp fibers are deposited on the inner surface of the cavity 13. As a result, a pulp layer 15 on which pulp fibers are deposited is formed on the inner surface of the cavity 13.

After the pulp layer 15 having a predetermined thickness is formed,
The injection of the pulp slurry is stopped, and the inside of the cavity 13 is completely sucked and dehydrated. Subsequently, as shown in FIG. 3B, the inside of the cavity 13 is suctioned and decompressed, and the elastic, elastic, and hollow core 16 is inserted into the cavity 13. The core 16 is inflated like a balloon in the cavity 13 and presses the pulp layer 15 against the inner surface of the cavity 13, so that the cavity 13
It is used to give the inner surface shape. Therefore, core 1
Reference numeral 6 is made of urethane, fluorine-based rubber, silicone-based rubber, elastomer, or the like, which is excellent in tensile strength, rebound resilience, stretchability and the like. The core 16 may be a hollow bag.

Next, as shown in FIG.
The pressurized fluid is supplied to the inside to expand the core 16, and the expanded core 16 presses the pulp layer 15 against the inner surface of the cavity 13. Then, the pulp layer 15 becomes the expanded core 1.
6 depresses against the inner surface of the cavity 13, the shape of the inner surface of the cavity 13 is transferred to the pulp layer 15, and dehydration further proceeds. Thus, since the pulp layer 15 is pressed against the inner surface of the cavity 13 from the inside of the cavity 13, the shape of the inner surface of the cavity 13 is accurately transferred to the pulp layer 15 even if the shape of the inner surface of the cavity 13 is complicated. Will be done. 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 molded body is increased and the appearance impression is improved. As the pressurized fluid used to expand the core 16, for example, compressed air (heated air), oil (heated oil), and other various liquids are used. The pressure for supplying the pressurized fluid is 0.0
It is preferable to make it 1-5 MPa, especially 0.1-3 MPa.

When the shape of the inner surface of the cavity 13 is sufficiently transferred to the pulp layer 15 and the pulp layer 15 can be dehydrated to a predetermined moisture content, as shown in FIG. Pull out. Then, the core 16 automatically shrinks and returns to its original size. Next, the contracted core 16 is taken out of the cavity 13, and the mold 10 is further opened to take out a wet intermediate body 15 'having a predetermined moisture content.

The removed intermediate 15 'is then subjected to a heating and drying step. In the heating / drying step, the same operation as the paper making step shown in FIG. 3 is performed except that the paper making / dewatering is not performed. That is, first, a mold in which a cavity having a shape corresponding to the outer shape of the molded body 1 to be molded is heated to a predetermined temperature by abutting a pair of split dies, and the mold in a state wet in the mold is heated. Load the above intermediate.

Next, a core similar to the core 16 used in the papermaking process is inserted into the intermediate body, and a pressurized fluid is supplied into the core to expand the core, thereby expanding the core. The core presses the intermediate 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 above-described papermaking process. In this state, the intermediate is dried by heating. When the intermediate is sufficiently dried, the pressurized fluid in the core is drained, and the core is shrunk and taken out. Further, the mold is opened, and the molded article 1 is taken out.

The molded body 1 manufactured in this manner has an angle θ between the ground surface of the bottom 4 and the outer surface of the side wall of the body 3 of 85.
°, and the height of the trunk 3 is 50 mm or more. Moreover, the outer surface and the inner surface of the molded body 1 are both smooth, and there is no seam due to bonding.

The present invention is not limited to the above-described embodiment. For example, a plastic layer or a shrink film layer or a coating layer may be provided on the outer surface and / or inner surface of the molded body 1 to reduce the strength of the molded body 1. The height may be further increased, leakage of contents may be effectively prevented, or decoration may be applied. In addition, a reinforcing member made of plastic or the like may be provided at a portion where a load is applied when the molded body 1 is used, for example, at the opening 2 or the bottom 4 so as to improve the durability of the molded body 1. 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 molded article of the present invention may be applied not only to a hollow container used for housing contents but also to an object such as an ornament.

[0033]

According to the present invention, it is possible to obtain a pulp mold hollow molded body having a large rising angle of the side wall and a deep bottom. Such a molded article has low production costs and can be reused or incinerated after use, which leads to a reduction in waste.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a pulp mold hollow molded body of the present invention.

FIG. 2 is a longitudinal sectional view of the pulp mold hollow molded body shown in FIG.

3 (a) to 3 (d) are process diagrams sequentially showing a paper making process in the process of manufacturing the pulp mold hollow molded article of the embodiment shown in FIG. 1.

FIG. 4 is a cross-sectional view of a body portion of the pulp mold hollow molded body shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulp mold hollow molded object 2 Opening 3 Body 4 Bottom B Grounding surface

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 50-149460 (JP, U) JP-B 35-9669 (JP, B1) JP-B 47-25257 (JP, Y1) (58) Field (Int.Cl. ⁷ , DB name) B65D 1/00-1/48 D21J 1/00-7/00

Claims (9)

(57) [Claims] 1. An apparatus according to claim 1, further comprising a bottom portion and a body portion, wherein an angle θ between the ground contact surface of the bottom portion and an outer surface of a side wall of the body portion is greater than 85 °, and Thickness T
2 is a pulp molded hollow molded body formed mainly of pulp, wherein the thickness is larger than the thickness T1 of the other part and the height of the body is 50 mm or more. 2. The pulp molded hollow molded article according to claim 1, wherein the body and the bottom are connected to each other via a curved surface. 3. The pulp molded hollow molded article according to claim 1, wherein no joint is present. 4. The pulp molded hollow molded article according to claim 1, wherein said bottom portion comprises a central concave portion and a heel portion surrounding said central concave portion. 5. The pulp molded hollow molded article according to claim 1, which is obtained by depositing pulp fibers on an inner surface of a cavity of a mold having a cavity therein. 6. The method according to claim 1, wherein T2 / T1 is 1.5 to 2.
6. The pulp mold hollow molded article according to any one of items 5 to 5. 7. The pulp fiber thus deposited is hollowed out.
6. The drying process wherein the core is pressed and dried by expansion of the core.
Pulp mold hollow molded article. 8. In the longitudinal section and / or in the transverse section.
The density ρ2 of the above corner part is the density of the other part.
The pulp according to any one of claims 1 to 7, which is smaller than ρ1.
Hollow molded body. 9. The density ρ2 and ρ1 are 0.1 ×
9. The pulp according to claim 8, wherein the relationship ρ1 <ρ2 <ρ1 is satisfied.
Hollow molded body.