Technical Field:
[0001] The present invention relates to a molded article comprising pulp as a major component.
Background Art:
[0002] Plastics are used as common materials of hollow containers, such as containers with
a lid and bottles, for their excellent molding properties and productivity. However,
because plastic hollow containers involve various problems associated with waste disposal,
hollow containers made of pulp are conceivable substitutes for plastic containers.
Pulp-made hollow containers are not only easy to dispose of but economical because
they can be manufactured from used paper.
[0003] Known techniques pertaining to pulp-made hollow containers include the technique
disclosed in Japanese Patent Laid-Open No. 5-279998. The container disclosed has an
angle of 45° or more at which the side walls rise and a depth of 15 mm or more. Because
this container is produced by pressing a pulp layer deposited on a papermaking net
with a pressing mold and then hot pressed in a metal mold, it is virtually impossible
to make the side walls stand at an angle approximately 90° or more and to make the
bottom deeper.
[0004] A bottle having an annular rib-like projection on its periphery is also known as
another technique relating to pulp molded containers. Since the bottle is made by
separately forming a pulp layer on each of a pair of splits and then closing the splits
to join the two pulp layers, it unavoidably has seams at the joint. Such seams reduce
the bottle strength and also impair the appearance.
[0005] Accordingly, an object of the present invention is to provide a molded article made
mainly of pulp the side walls of which have a large angle to the ground and which
has a large depth.
[0006] Another object of the present invention is to provide a molded article made mainly
of pulp which involves no reduction in bottle strength, has a satisfactory appearance,
and has a depression or a projection of prescribed shape around the opening or the
body thereof.
Disclosure of the Invention:
[0007] The present invention achieves the above object by providing a molded article made
predominantly of pulp and comprising a bottom portion and a body portion, wherein
the angle between the outer surface of a side wall of said body portion and the ground
contact plane of said bottom portion is 85° or greater, and the height of said body
portion is 50 mm or more (hereinafter referred to as a first aspect).
[0008] The present invention also achieves the above object by providing a molded article
made predominantly of pulp and comprising a bottom portion, a body portion and an
opening portion, wherein said body portion has a depression or a projection, or said
opening portion has an extension extending inward from the peripheral edge thereof,
said depression or said projection is continuous only in the horizontal or oblique
direction provided that said depression or said projection is continuous in a straight
line, and said body portion is seamless (hereinafter referred to as a second aspect).
Brief Description of the Drawings:
[0009]
Fig. 1 is a perspective view of an embodiment of the molded article according to the
present invention.
Fig. 2 is a vertical cross-section of the molded article shown in Fig. 1.
Fig. 3 is a transverse cross-section of the body portion of the molded article shown
in Fig. 1.
Figs. 4(a), 4(b), 4(c), and 4(d) show in sequence a papermaking step out of the steps
for producing the molded article shown in Fig. 1.
Fig. 5 is a vertical cross-section of an embodiment of the molded article according
to the second aspect (corresponding to Fig. 2).
Fig. 6 is a vertical cross-section of another embodiment of the molded article according
to the second aspect (corresponding to Fig. 2).
Fig. 7 is a perspective of a second embodiment of the molded article according to
the first aspect.
Fig. 8 is a side view of the molded article shown in Fig. 7.
Figs. 9(a) and 9(b) each show a cross-section of a preferred configuration of a first
hinge and a second hinge.
Fig. 10 schematically shows a pulp slurry being injected into a mold which is preferably
used in the production of the molded article shown in Fig. 7.
Fig. 11 is a perspective of a third embodiment of the molded article according to
the first aspect.
Fig. 12 is a side view of the molded article shown in Fig. 11.
Fig. 13 schematically illustrates hinge formation in an embodiment of the method of
producing the molded article shown in Fig. 11.
Fig. 14 is a perspective of a fourth embodiment of the molded article according to
the first aspect.
Fig. 15 is a perspective of a fifth embodiment of the molded article according to
the first aspect.
Fig. 16 is a cross-section of Fig. 15 taken along line A-A, showing a measuring container
being fitted between fitting projections.
Fig. 17 is a perspective of a sixth embodiment of the molded article according to
the first aspect.
Fig. 18 is an enlarged view of a fitting part for a handle.
Fig. 19 is a perspective of a seventh embodiment of the molded article according to
the first aspect.
Fig. 20 is an exploded perspective of a mold which is preferably used in the production
of the molded article according to the seventh embodiment.
Fig. 21 is a vertical cross-section of the mold shown in Fig. 20, taken along the
parting face.
Figs. 22(a) and 22(b) show part of a papermaking step out of the steps for producing
the molded article according to the embodiment shown in Fig. 19.
Fig. 23 is a vertical cross-section of an eighth embodiment of the molded article
according to the first aspect.
Figs. 24(a), 24(b), 24(c), and 24(d) show in sequence the step of laminating the inner
surface of a molded article with a plastic film.
Fig. 25 is a partial perspective of a molded article covered with a shrink film, with
part cut away.
Figs. 26(a) and 26(b) show the step of covering the outer surface of a molded article
with a shrink film.
Best Mode for Carrying out the Invention:
[0010] Preferred embodiments of the molded article according to the first aspect of the
present invention will be illustrated with reference to the accompanying drawings.
Figs. 1 and 2 show a perspective and a vertical cross-section, respectively, of
a molded article 10 according to the first embodiment of the first aspect. The molded
article 10 is a hollow container suitable for holding such contents as powder or granules.
It has an opening portion 11 in the upper part, a body portion 12, and a bottom portion
13.
[0011] The body portion 12 and the bottom portion 13 connect by a curved portion 12' to
give the molded article 10 increased impact strength. The curvature of the curved
portion 12' is preferably 0.5 mm or more, particularly 5 mm or more, especially 7
mm or more, from the standpoint of improvements on impact strength, drying efficiency,
surface finish, and adhesion to a plastic film that is used in the eighth embodiment
hereinafter described. The transverse cross-section of the molded article 10 is a
rectangle with its four comers rounded to give the molded article 10 increased impact
strength. The curvature of the four comers is preferably 0.5 mm or more, particularly
5 mm or more, especially 7 mm or more, for the same reasons as described as for the
curved portion 12'. The four sides of the rectangle are gently curved outward. The
body portion 12 has a continuous depression 14 around its circumference to make the
molded article 10 easy to hold. The depression 14 will be described later in detail.
[0012] The front and rear walls making the body portion 12 form straight lines (except for
the depression 14) in the height direction of the molded article 10 when seen from
the side. Likewise the right and left walls making the body portion 12 form straight
lines (except for the depression 14) in the height direction when the molded article
10 is seen from the front.
[0013] The bottom portion 13 is made up of a central depression 15 and a heel 16 continuously
surrounding the central depression 15. The outer surface of the heel 16 is brought
into contact with the ground. Such a configuration of the bottom portion 13 secures
stability of the molded article 10 when placed on its bottom.
[0014] The molded article 10 has smooth outer and inner surfaces. In case where a plastic
layer or a coating layer is formed on the outer and/or the inner surfaces as hereinafter
described, the surface smoothness will secure satisfactory adhesion to the layer.
Further, the surface smoothness would facilitate neat printing on the outer surface
and also provides a better outer appearance. The terminology "smooth" as used herein
means that the surface profile of the outer and inner surfaces of the molded article
is such that the center-line average roughness (Ra, JIS B0601) is 50 µm or less, and
the maximum height (R
max, JIS B0601) is 500 µm or less.
[0015] As shown in Fig. 2, the molded article 10 has every side wall (front, rear, right,
and left) of the body portion 12 standing with its outer surface making an angle θ
exceeding 85°, preferably 89° or more, to the ground contact plane B of the bottom
portion 13 (the angle θ in Fig. 2 is approximately 90°) and a height h (see Fig. 2)
of 50 mm or more, preferably 100 mm or more. The angle θ can exceed 90°. It is virtually
impossible for the container disclosed in Japanese Patent Laid-Open No. 5-279998
supra, being subject to various designing restrictions, to have its side walls standing
at such a large angle and to have such a deep bottom. The present invention gets rid
of such inconveniences. The outer surface of the side wall, from which the angle θ
is measured, is the part that forms a straight line in the molded article's height
direction when viewed from the front or the side of the molded article 10. Accordingly,
the outer surface of the depression 14 formed on the body portion 12 is excluded from
the object of measurement.
[0016] Unlike conventional hollow pulp molded articles, the molded articles 10 according
to this embodiment has no seams nor thick-walled parts around the body portion 12
and between the body portion 12 and the bottom portion 13. Thus, the molded article
has increased strength and a satisfactory appearance.
[0017] The molded article 10 comprising pulp as a major component. Of course it can be 100%
pulp made. When other minor materials are used in addition to pulp, the proportion
of the other materials is preferably 1 to 70% by weight, particularly 5 to 50% by
weight. Useful other materials include inorganic substances such as talc and kaolinte,
inorganic fibers such as glass fiber and carbon fiber, powder or fiber of synthetic
resins such as polyolefin, nonwood or plant fibers, and polysaccharides.
[0018] The molded article 10 formed of the above-described raw materials preferably has
a density (i.e., the density of the wall of the container) of 0.4 to 2.0 g/cm
3 to have suitable rigidity as a hollow container, satisfying mechanical properties
such as tensile strength, compressive strength, drop strength, and strength at the
opening. Still preferably the density is 0.6 to 1.5 g/cm
3 to secure an excellent feel on use.
[0019] The molded article 10 which has a water vapor transmission rate of 100 g/(m
2·24 hrs) or less, preferably 50 g/(m
2·24 hrs) or less, as measured in accordance with JIS Z0208, absorbs little moisture
in the air and thereby retains moderate rigidity as a hollow container. As a result,
the contents are effectively protected against quality deterioration due to water
absorption. That is, the contents are given improved storage stability.
[0020] It is preferred for the molded article 10 to have a surface tension of 10 dyn/cm
or less and water repellency (JIS P8137) of R10. The molded article having such a
surface tension and a water repellency can be obtained by molding a paper stock comprising
the pulp slurry having incorporated therein additives, such as a waterproofing agent,
a water repellant, etc.
[0021] The molded article 10 which has a tensile strength of 5 MPa or more, particularly
10 MPa or more, is preferred for inhibiting rupture due to shocks, etc. The term "tensile
strength" as used herein means a breaking strength measured by the following procedure
in accordance with JIS P8113. A 15 mm wide by 140 mm long specimen is cut out of an
arbitrary portion of the molded article 10. The specimen is set on a tensile tester
at a chuck distance of 100 mm. Then the specimen is pulled at a pulling speed of 20
mm/min. In case where the molded article cannot afford a specimen of the above size,
the size of a specimen to be measured can be changed appropriately.
[0022] The molded article 10 which has a specific compressive strength of 100 Nm
2/g or more, particularly 110 Nm
2/g or more, is preferred, for it is hardly collapsed when stacked up on top of another.
The term "specific compressive strength" as used herein is one measured in accordance
with JIS P8126.
[0023] It is preferred for the molded article 10 to have such a drop strength that it does
not break even when dropped 10 times in the drop test specified in JIS Z0217. The
opening portion of the molded article 10 preferably exhibits such strength that the
force required for pressing the opening portion 11 from its side to give a deformation
of 30 mm is 10N or greater.
[0024] It is preferred for the molded article 10 to have a larger thickness at the comers
in its vertical cross-section and/or transverse cross-section than the other portions
to improve the compressive strength (buckling strength) of the molded article 10 as
a whole over the one having equal thickness in every portion. For example, in the
vertical cross-section of the molded article 10 shown in Fig. 2, it is preferred that
the thickness T2 of the comers, i.e., curved portions 12', be greater than the thickness
T1 of the body portion 12 (i.e., T2>T1). In this case, where T2/T1 is 1.5 to 2, the
improvement on compressive strength of the whole molded article 10 is further secured.
It is preferred that the thickness T1 be 0.1 mm or greater for the molded article
10 to exhibit the minimum compressive strength required. It is required for the molded
article 10 to have a prescribed compressive strength, considering that the molded
articles 10 are to be transported or stacked up in a warehouse or a shop. Likewise,
it is preferred that the molded article 10 has a larger thickness at the comers (T2)
than in the other portions (thickness T1) in its transverse cross-section at the body
portion shown in Fig. 3.
[0025] Where the comers of the molded article 10 in the vertical cross-section and/or the
transverse cross-section satisfy the relationship that their density ρ2 is smaller
than the density ρ1 of the other portions (i.e., ρ1>ρ2) as well as the above-described
relationship between T1 and T2, there is produced an effect that two conflicting phenomena
- an improvement in compressive strength of the molded article 10 and a reduction
in amount of the material used - can result. This effect is more notable when 0.1
x ρ1<ρ2<ρ1. The molded article 10 which satisfies these relationships has a compressive
strength of 190 N or greater. The compressive strength as referred to here is the
maximum strength in compressing the molded article 10 in the direction of height at
a speed of 20mm/min. The above-described relationships between T1 and T2 and between
ρ1 and ρ2 can be established by, for instance, properly selecting conditions in carrying
out a preferred method for producing the molded article 10 which will be described
later, such as the pressure or flow rate of a pressurizing fluid used in pressing
with a pressing member 6, the material or shape of the pressing member 6, the shape
of the molded article, and the like.
[0026] For example, molded articles 10 which were produced so as to have the T1, T2, ρ1,
and p2 shown in Table 1 below in their transverse cross-section of the body portion
(see Fig. 3) had the compressive strength shown in Table 1. It is seen that the compressive
strength increases as the T2/T1 value increases and as the ρ2/ρ1 value decreases.
Moreover, the example 2 having a higher compressive strength is lighter. The values
T1, T2, ρ1, and ρ2 given in Table 1 are the respective averages of values measured
on four positions of the body portion in the height direction.
TABLE 1
| |
T1 (mm) |
T2 (mm) |
T2/T1 |
ρ2/ρ1 |
Compressive Strength (N) |
Weight (g) |
| Example 1 |
0.550 |
0.593 |
1.078 |
0.928 |
441 |
13.4 |
| Example 2 |
0.595 |
0.835 |
1.403 |
0.713 |
500 |
13.0 |
[0027] A preferred method for producing the molded article of the present embodiment will
be described with reference to Fig. 4. The molded article 10 of the present embodiment
is produced by pulp molding, particularly conveniently by depositing pulp on the inner
wall of a cavity formed in a mold. The papermaking step of the steps for producing
the molded article 10 by this method is illustrated in sequence in Figs. 4(a) through
(d), in which (a) is the step of papermaking, (b) is the step of inserting a pressing
member, (c) is the step of pressing and dewatering, and (d) is the step of opening
a split mold to remove a pulp deposited body.
[0028] As shown in Fig. 4(a), a pulp slurry is poured into a mold having a cavity 1. The
cavity 1, formed by joining a pair of splits 3 and 4, has a configuration in conformity
to the outer contour of a molded article 10 to be molded. Each of the splits 3 and
4 has a plurality of interconnecting holes 2 which connect the outer side thereof
and the cavity 1. The inner surface of the splits 3 and 4 is covered with a net (not
shown) of prescribed mesh.
[0029] The cavity 1 is evacuated from the outside of the splits 3 and 4 to suck water of
the pulp slurry and to deposit the pulp fiber on the inner wall of the cavity 1. As
a result, a pulp deposited body 5 is built up on the inner wall of the cavity 1.
[0030] On forming the pulp deposited body 5 of prescribed thickness, pulp slurry injection
is stopped, and the cavity 1 is completely dewatered by sucking. Subsequently, as
shown in Fig. 4(b), a hollow, stretchable and elastic pressing member 6 is inserted
into the cavity 1 while evacuating the cavity 1 as shown in Fig. 4(b). The pressing
member 6 is to be inflated in the cavity 1 like a balloon to press the pulp deposited
body 5 toward the inner wall of the cavity 1 to transfer the inner configuration of
the cavity 1. Therefore, the pressing member 6 is made of urethane, fluorine rubber,
silicone rubber, elastomers, etc., which are excellent in tensile strength, impact
resilience, stretchability, and the like. The pressing member 6 can be a hollow bag.
[0031] As shown in Fig. 4(c), a pressurizing fluid is fed into the pressing member 6 to
inflate it. The inflated pressing member 6 presses the pulp deposited body 5 to the
inner wall of the cavity 1. While the pulp deposited body 5 is pressed onto the inner
wall of the cavity 1 by the inflated pressing member 6, the configuration of the inner
wall of the cavity 1 is transferred thereto, and dewatering further proceeds at the
same time. Since the pulp deposited body 5 is pressed from the inside to the inner
wall of the cavity 1 in this manner, the inner configuration of the cavity 1 can be
transferred to the pulp deposited body 5 with good precision however complicated the
configuration may be. Unlike the conventional production process, the resulting molded
article has no seams nor thick-walled parts due to joining since the present process
involves no step of joining. As a result, the resulting molded article has secured
strength and a satisfactory appearance. The pressurizing fluid for inflating the pressing
member 6 includes compressed air (heated air), oil (heated oil) and other liquids.
The pressure for feeding the pressurizing fluid is preferably 0.01 to 5 MPa, particularly
0.1 to 3 MPa.
[0032] After the configuration of the inner wall of the cavity 1 is sufficiently transferred
to the pulp deposited body 5, and the pulp deposited body 5 is dewatered to a prescribed
water content, the pressurizing fluid is withdrawn from the pressing member 6, whereupon
the pressing member 6 shrinks automatically to its original size as shown in Fig.
4(d). The shrunken pressing member 6 is taken out of the cavity 1, and the mold is
opened to remove the wet pulp deposited body 5 having the prescribed water content.
[0033] The pulp deposited body 5 thus taken out is then subjected to the step of heat drying.
In the step of heat drying, the same operation as in the papermaking step shown in
Fig. 4 is conducted, except that papermaking and dewatering are not carried out. That
is, a mold, which is composed of a pair of splits joined together to form a cavity
in conformity to the outer contour of a desired molded article, is heated to a prescribed
temperature, and the wet pulp deposited body is set in the mold.
[0034] A pressing member similar to the pressing member 6 used in the papermaking step is
put into the pulp deposited body, and a pressurizing fluid is fed into the pressing
member to inflate it, whereby the pulp deposited body is pressed onto the inner wall
of the cavity by the inflated pressing member. The material of the pressing member
and the pressure for feeding the pressurizing fluid can be the same as those used
in the papermaking step. In this state, the pulp deposited body is dried by heat.
After the pulp deposited body dries thoroughly, the pressurizing fluid is withdrawn
from the pressing member, and the shrunken pressing member is taken out. The mold
is opened to remove the molded article 10.
[0035] The molded article 10 thus produced has an angle exceeding 85° between the ground
contact plane of the bottom 13 and the outer surface of the side wall of the body
12 and a body 12 height of 50 mm or more. Both the outer and the inner surfaces of
the molded article 10 are smooth with no joint seams.
[0036] The second aspect of the present invention will be described with reference to Figs.
5 and 6. The description about the first aspect appropriately applies to the particulars
that are not specifically explained here.
[0037] The molded article 10 of the second aspect shown in Fig. 5 has almost the same construction
as the molded article of the first aspect shown in Figs 1 through 3. The body portion
12 has a continuous depression 14 around its circumference similarly to the first
aspect. The molded article 10 shown in Fig. 6 has a projection 14' in place of the
depression around the circumference of the body portion 12. Both the molded articles
10 shown in Figs. 5 and 6 have an extension 7 extending inwardly from the peripheral
edge of the opening portion 11. The extension 7 serves to strengthen the opening portion
11. When the opening 11 is closed with seal, etc., the upper side of the extension
17 serves as a sealing surface. The depression 14, the projection 14', and the extension
17 are equivalent to what we call "undercuts" in the field of injection molding of
plastics, and the terms "depression", "projection", and "extension" as used herein
include any parts equivalent to what is called "undercuts". Accordingly, a depression
or a projection formed continuously in a straight line in the vertical direction of
the molded article 10, being not equivalent to an undercut, is excluded from what
is intended by the term "depression" or "projection" in the context of the present
invention. In other words, where a depression or a projection is continuous linearly,
it is continuous only in the horizontal direction or an oblique direction of the molded
article 10. With conventional pulp molding methods, it has been impossible to make
a container having the above-identified depression 14, projection 14' or extension
17 and yet having no seams of joints. Because the molded articles of the present invention
are seamless notwithstanding the depression 14, the projection 14' and the extension
17, they are free from the problem of strength reduction and have a satisfactory appearance.
[0038] In an embodiment of the second aspect, a depression 14 and/or a projection 14' can
be formed to provide the body portion 12 with three-dimensional letters, figures or
symbols. Further, the extension 17 of the molded article 10, which is formed on the
peripheral edge of the opening portion 11, can be discontinuous.
[0039] The second to eighth embodiments of the first aspect of the present invention are
then described with reference to Figs. 7 through 26. Only the particulars different
from the first embodiment will be explained. The description about the first embodiment
appropriately applies to the particulars that are not specifically explained here.
The members in Figs. 7 to 26 which are the same as those in Figs. 1 to 4 are given
the same numerical references as used in Figs. 1 to 4. Unless otherwise noted, the
second to eight embodiments of the first aspect shall apply to the second aspect.
[0040] As shown in Figs. 7 and 8, a molded article of the second embodiment has a lid which
swings to open and shut the opening portion 11. The lid and/or a measuring container
are connected to the molded article 10 by integral molding via a first hinge and/or
a second hinge which is/are thin and dense.
[0041] The lid 18, which is integrally molded with the molded article 10, links up with
the molded article 10 near the opening portion 11 by the first hinge 31 so as to open
and close the opening portion 11. The lid 18 consists of a flat top 32 and peripheral
wall 33 standing upright from the peripheral edge of the top 32 so that the lower
edge 33a of the peripheral wall 33 may be brought into, or out of, contact with the
fitting part of the molded article 10. The lid 18 and the molded article 10 link up
between the lower edge 33a of the peripheral wall 33 of the former and the horizontal
contact part 25 of the latter.
[0042] The measuring container 19 is also integrally molded with the molded article 18 similarly
to the lid 18. The measuring container 19 links up with the molded article 10 by the
second hinge 41. The measuring container 19 is a scoop composed of a cup 42, which
is a closed-end rectangular cylinder, and a handle 43 integrally connected to the
cup 42. The measuring container 19 connects up with the molded article 10 near the
opening portion 11 by a linking part 44 having the second hinge 41. As shown in Fig.
8, the measuring container 19 swings on the second hinge 41 to be put inside the molded
article 10 without projecting over the opening portion 11. This construction permits
the opening portion 11 to be sealed with seal, etc.
[0043] The lid 18 and the measuring container 19 are integrally molded together with the
molded article 10 and link up with the molded article 10 via the first hinge 31 and
the second hinge 41, respectively. The first hinge 31 is a thin and dense part formed
in a linking part between the lid 18 and the molded article 10. The second hinge 41
is a thin and dense part formed in a linking part between the measuring container
19 and the molded article 10.
[0044] More specifically, the linking part which links the lid 18 and the molded article
10 and the linking part which links the measuring container 19 and the molded article
10 each have a linear groove having a prescribed cross-section to make the first hinge
31 and the second hinge 41. The lid 18 swings in an arc on the first hinge 31 to open
and shut the opening portion 11 of the molded article 10. The measuring container
19 similarly swings on the second hinge 41 to be put inside the molded article 10.
[0045] The first hinge 31 and the second hinge 41 are thinner than the other portions of
the molded article 10, the lid 18 and the measuring container 19. The thickness T1
at the thinnest of the first and second hinges 31 and 41 (see Fig. 9) is preferably
0.05 mm or greater and from 5 to 100%, still preferably 15 to 80%, of the other portions
of the molded article 10, the lid 18 and the measuring container 19 in order to obtain
excellent flexing property and durability. While every part of the molded article
10, the lid 18, and the measuring container 19 can be of a thickness and a density
except the first and second hinges, the preferred range of the thickness T1 of the
first and second hinges and a preferred range of the density of the first and second
hinges (hereinafter described) are represented based on the thickness and density
of the body portion 12 of the molded article 10 as a standard.
[0046] The first and second hinges 31 and 41 are denser than the other portions of the molded
article 10, the lid 18 and the measuring container 19. For obtaining excellent flexing
properties and durability, the density of the first and second hinges 31 and 41 is
1.05 to 20 times, preferably 2 to 20 times, particularly preferably 2 to 5 times,
that of the other portions of the molded article 10, the lid 18 and the measuring
container 19. From the same viewpoint, a preferred density of the hinges 31 and 41
is 0.4 to 2.0 g/cm
3. The density of the hinge is a maximum density of the hinge, which is calculated
from thickness and weight measurements per given area.
[0047] For obtaining excellent flexing properties and durability, it is preferred for the
first and second hinges 31, 41 to have a tensile strength of 5 MPa or greater and
a specific compressive strength of 100 N·m
2/g or greater. From the same standpoint, the width of the first and second hinges
31, 41 (the width in the direction of linking the molded article 10 with the lid 18
or the measuring container 19) is preferably 0.2 mm or more, particularly 1 mm or
more. The "width of the hinge" as referred to here is the smallest width of the groove
on the side facing outward when the linking part is bent.
[0048] Two preferred configurations of the hinges 31 and 41 are shown in Fig. 9. The hinge
of Fig. 9(a) is formed by making a groove on both the upper and the lower sides of
the linking part between the molded article 10 and the lid 18 or the measuring container
19. The hinge of Fig. 9(b) is formed by making a groove on only the lower side of
the linking part. The upper side in Fig. 9 corresponds to the side facing inward when
the linking part is bent. The "width of the hinge" is, in Fig. 9(a), a width W1 of
the lower side groove at the deepest; and, in Fig. 9(b), a width W3 of the groove
at the deepest. The angular part in the grooves indicated by symbol "CorR" is preferably
chamfered or rounded. Preferred dimensions of each part of the hinges shown in Fig.
9 are as follows. The width W2 in Fig. 9(a), which is the width of the groove facing
inward on bending as measured on the surface level, is preferably 1 mm or greater.
The width W3, which is at the deepest of the hinge of Fig. 9(b), is preferably 0.2
mm or greater and equal to or smaller than the width W4, which is the width of that
groove on its surface level. The width W4 is preferably 1 mm or greater.
[0049] In the present embodiment, it is preferred that not only the molded article 10 but
the lid 18 and the measuring container 19 be made mainly of pulp.
[0050] Since the first hinge 31 which connects the lid 18 and the molded article 10 is thin
and dense as described above, repeated swings of the lid 18 do not cause the inconvenience
of the hinge 31's being torn off. Therefore, the molded article 10 is favorable for
use as a container from which the contents are repeatedly taken out in small portions.
[0051] Also linking up with the molded article 10 by the second thin and dense hinge 41,
the measuring container 19 is not torn off the molded article 10 at the linking part
during transportation. Bent and put inside the molded article 10, the measuring container
19 does not fall off during transportation. On use, the measuring container 19 is
cut off the molded article 10 at the linking part 44 with a pair of scissors or a
cutter.
Since the molded article 10, the lid 18 (arid the measuring container 19) are integrally
molded, the production process can be simplified to reduce the production cost. Not
only the molded article 10 but the lid 18 (and the measuring container 19), being
made mainly of pulp, can easily be disposed of. These portions can be produced from
used paper, which is economically advantageous.
[0052] The molded article 10 according to the present embodiment can be produced almost
in the same manner as shown in Fig. 4 by use of a mold shown in Fig. 10. In detail,
the lid 18 and the measuring container 19 are integrally molded together with the
molded article 10 by a papermaking technique to obtain a molded article precursor,
which is a pulp deposited body obtained after papermaking and dewatering. A part of
the linking part between the molded article 10 and the lid 18 or the measuring container
19 is compressed to form the first hinge 31 and the second hinge 41. The term "molded
article precursor" as used herein means a pulp fiber deposited body having a given
shape which is obtained after papermaking and dewatering steps. A molded article after
pressing and drying steps is also included under this term.
[0053] The difference between the method of producing the molded article of this embodiment
and that shown in Fig. 4 is that the molded article precursor after the heat drying
step is once removed from the mold and placed on a separate member, or the molded
article precursor after the heat drying step is kept in contact with a half of the
split mold, and the parts of the precursor that become the first and second hinges
31 and 41 are compressed to form the first and second hinges 31 and 41. The compression
is preferably carried out by pressing the parts becoming the first and second hinges
31 and 41 with long and narrow projections whose cross-sections correspond to the
shapes of the first hinge 31 and the second hinge 41, respectively. Where the molded
article precursor is the one after the papermaking and dewatering steps but before
the heat drying step, the formation of the first hinge 31 and/or the second hinge
41, which are made thinner and denser than the other portions, can be carried out
more easily and efficiently by compressing the parts that become the first and second
hinges 31 and 41.
[0054] According to the above-described method, the molded article 10 of the present embodiment
can be produced efficiently and economically.
The molded article 10 can also be produced by depositing pulp on the inner surface
of a papermaking mold, such as a base mold having a net laid thereon or a porous mold,
to form a pulp layer, dewatering the pulp layer in a known manner, transferring the
resulting molded article precursor to either a female mold or a male mold making a
couple, and pressing and drying the precursor with a mating male or female mold. In
this method, the first hinge 31 and/or the second hinge 41 can be formed by compressing
the corresponding parts of the precursor after the pressing and drying step. The first
hinge 31 and/or the second hinge 41 can also be formed simultaneously with the pressing
and drying step by pressing the corresponding parts with projections for hinge formation
provided on the corresponding parts of a pressing and drying mold. Where the first
and second hinges 31 and 41 are formed during the pressing and heating step, a movable
pressing member can be provided on part of the mold so that the precursor may be pressed
by this member in an appropriate stage in the pressing and drying step to form the
first and second hinges 31 and 41. This method is also efficient in producing the
molded article 10 according to the present embodiment.
[0055] While the molded article 10 according to the present embodiment has both the lid
18 and the measuring container 19 linked to the molded article 10 near the opening
portion 11 by the thin and dense hinges 31 and 41, respectively, it is conceivable
that the molded article 10 has either one of the lid 18 and the measuring container
19 linked thereto by a thin and dense hinge. The measuring container 19 can be omitted.
The measuring container 19 is not particularly limited and can be of various shapes
and capacities, provided that the object of measuring is fulfilled.
[0056] A molded article of the third embodiment has a lid for opening and shutting the open
top thereof as shown in Figs. 11 and 12. The lid is a part which is separately prepared
from the molded article and has a linking part with a hinge through which it is fixed
to the molded article.
[0057] In detail, the lid 18 is made separately from the molded article 10. It is fixed
to the main body 2 of the container via the linking part 31' having the hinge 31 which
is provided on the lid 18. The structure of the lid 18 is the same as in the second
embodiment.
[0058] The linking part 31' is provided at the lower edge 33a of the peripheral wall 33
as an integral part that is formed by integral molding together with the lid 18. The
linking part 31' is almost rectangular and has the hinge 31 in the middle thereof.
The lid 18 in this embodiment is formed mainly of pulp, and the hinge 31 is formed
as a thin and dense part of the linking part 31'. More specifically, a long, narrow,
and straight groove having an arched cross-section is made in the middle of the linking
part 31' to form the hinge 31. The part of the linking part 31' that is farther than
the hinge 31 is a joint face 31a which is adhered to the body portion 12 of the molded
article 10. In the present embodiment, the linking part 31' is adhered to the body
portion 12 by bringing the joint face 31a into contact with the body portion 12 and
sticking an adhesive sealing member 31b over the joint face 31a as shown in Fig. 11.
The lid 18 is thus fixed so that it can swing in an arc on the hinge 31 to open and
close the opening portion 11 of the molded article 10.
[0059] Preferred configurations of the hinge 31 are the same as those shown in Fig. 9. Other
details of the first hinge in the second embodiment also apply to the hinge 31.
[0060] As stated previously since the molded article 10 according to the present embodiment
has the lid 18, which is prepared separately from the molded article 10, fixed to
the molded article 10, it is produced without using a large sized mold, which is productive
and economical.
[0061] In producing the molded article of the present embodiment, the linking part 31' is
integrally molded together with the lid 18 by a papermaking method, and a part of
the linking part 31'-forming part of the molded article precursor after papermaking
and dewatering is compressed to form the hinge 31. The term "molded article precursor"
as used herein has the same meaning as defined with respect to the second embodiment.
The term "linking part 31'-forming part" as used herein indicates a part which finally
becomes the linking part 31'.
[0062] The molded article 10 can be produced by the same method as shown in Fig. 4 for the
first embodiment. The lid 18 can be produced through almost the same steps as for
the main body of the container 2.
That is, the steps from papermaking and dewatering up to heat drying are carried
out in the same manner as for the preparation of the molded article 10, except for
using a mold composed of a pair of splits forming a cavity configuration in conformity
to the contour of the lid 18 to be molded.
[0063] The molded article precursor after the heat drying step is once removed from the
mold and placed on a separate member, or the molded article precursor after the heat
drying step is kept in contact with a half of the split mold. In this state, a part
of the linking part 31'-forming part of the molded article precursor is compressed
to form the hinge 31. As shown in Fig. 13, the compression is preferably performed
by pressing a part of the linking part 31'-forming part 46 of the molded article precursor
45 with projections 47 whose cross-sections correspond to the shape of the hinge 31.
The lid 18 thus prepared is fixed to the molded article 10 via the linking part 31'
in such a manner that it can swing on the hinge 31 to be fitted to the fitting part
of the molded article 10. With respect to the other particulars of the hinge formation
that have not been described, the corresponding description given to the hinge formation
in the second embodiment appropriately applies.
[0064] In the present embodiment, the shape and the number of the linking part(s) 31' are
not particularly limited as long as the lid 18 and the molded article 10 are linked
together thereby. For example, a spaced pair of linking parts 31' can be attached
to the molded article 10. As long as the linking part 31' can be fixed to the molded
article 10, the manner of fixing is not particularly restricted. For instance, the
joint face 31a can be adhered to the outer surface of the molded article 10 directly
with an adhesive, or a hole can be made in the molded article 10 into which part of
the linking part 31' can be fitted. It is also possible to omit the linking part 31'
and to link the lid 18 to the molded article 10 by means of tape made of paper, etc.
The linking part 31' can be attached to any position of the molded article 10 provided
that the lid 18 is fixed in such a manner that it may open and close the opening portion
11 of the molded article 10.
[0065] The lid 18 does not always need to be made mainly of pulp but can be an injection
molded part made of a synthetic resin.
[0066] A molded article according to the fourth embodiment has its upper opening covered
with a seal and a measuring container removably set on the seal as shown in Fig. 14.
[0067] According to this embodiment, the measuring container can easily be taken out for
use without soiling a user's hand and with no need of assembly.
[0068] As shown in Fig. 14, a seal 63 having a removable measuring container 19 is provided
to cover the upper surface of the opening portion 11 of the molded article 10.
[0069] In the present embodiment, both the seal 63 and the measuring container 19 are made
by pulp molding. They can easily be prepared by integral molding according to the
method described, e.g., in Japanese Patent Laid-Open No. 5-279998.
[0070] That is, a pulp component is extracted from a pulp slurry on a papermaking net formed
into the integral shape of the seal 63 and the measuring container 19. The formed
pulp layer is pressed from the upper side with a pressing mold made of an elastic
material to remove the water content from the pulp layer to obtain a molded container
precursor, which is hot pressed to obtain easily an integral pulp molded article which
is the seal 63 having a three-dimensional measuring container 19 as a depression.
[0071] After the integral molding, a cutting line is printed along the border between the
seal 63 and the measuring container 19, or discontinuous cuts, perforations or thinner
parts are made along the border thereby to make it easy to separate the measuring
container 19 from the seal 63 by hand. Perforations, etc. can be made by molding.
[0072] After the molded article 10 is filled with, for example, powdered detergent, the
seal 63 having the measuring container 19 as an integral part thereof is adhered at
its periphery to the upper end of the molded article 10 with an adhesive to cover
the opening portion 11 of the molded article 10. The powdered detergent is thus sealed
in. Thereafter, the pulp molded lid 18, which is hinged to the upper side of the molded
article 10, is swung shut.
[0073] On use, the lid 18 is swung open, the seal 63 is removed to open the molded article
10, and the measuring container 19 is separated from the seal 63. A predetermined
amount of the powdered detergent can be measured with the measuring container 19 and
put into a washing machine, etc.
[0074] According to the present embodiment, since the measuring container 19 is removably
set on the seal 63, it does not bury itself in powdered detergent, causing no such
troubles for a user to find it out or soil her or his hand to take it out.
[0075] Further, because the molded article 10, the seal 63, the measuring container 19,
and the lid 18 are all formed by pulp molding, they are easy to dispose of.
[0076] In the present embodiment, the seal, the measuring container and the lid do not always
need to be pulp molded articles and can be made of plastics and the like. Removably
setting the measuring container to the seal may be such that the measuring container
is releasably adhered to the seal with an adhesive.
[0077] A molded article according to the fifth embodiment has a fitting part for a measuring
container integrally molded as shown in Fig. 15.
[0078] According to this embodiment, the measuring container is fitted to a prescribed position
of the molded article so that it is easily detached.
[0079] As shown in Fig. 15, fitting projections 70 are integrally formed on the upper inner
wall of the molded article 10, between which a cup 71 of a three-dimensional measuring
container 19 made of plastics, etc. is detachably fixed.
[0080] As shown in Fig. 16, the fitting projections 70 for fitting the measuring container
19 to the upper inner wall of the molded article 10 are a pair of an upper rib and
a lower rib each having a semicircular cross-section which are parallel to each other
at a spacing corresponding to the distance between two facing edges of the cup 71
so that the two edges of the cup 71 may be fitted in. The cup 71 of the measuring
container 19 is laterally slid in between the pair of the fitting projections 70 with
its edges in contact with the inner wall of the molded article 10. The two edges of
the cup 71 are thus fastened by the upper and lower fitting projections 70, and the
measuring container 19 is fixed to the inner wall of the molded article 10. On use,
the measuring container 19 is easily detached by sliding backward. The fitting projections
70 are integrally molded together with the molded article 10.
[0081] Since the molded article 10 according to the present embodiment has a pair of the
fitting projections 70 on its upper inner wall as a fitting part for the three-dimensional
measuring container 19, it can hold the measuring container 19 fixed thereto. Therefore,
the measuring container 19 is not buried in powdered contents due to vibrations, etc.
and can easily be taken out. The fitting projections 70 being formed on the upper
inner side of the molded article 10, the measuring container 19 is positioned above
the powdered contents so that it can be taken out without soiling a user's hand.
[0082] In the present embodiment, the measuring container can be disposed on the outer side
or lower part of the molded article or on the seal instead on the upper inner side
of the molded article. The measuring container fitting part is not limited to the
rib-like projections and can be composed of other various projections formed as integral
parts by a pulp molding method.
[0083] A molded article according to the sixth embodiment has a fitting part for a handle
on its body portion, on which a handle is hooked up as shown in Fig. 17.
[0084] According to this embodiment, a molded article equipped with a handle which is easy
to dispose of or recycle is provided at a low cost of production. In particular, a
molded article and a handle both of which are made of pulp would be easier to dispose
of or recycle.
[0085] The body portion 12 of the molded article 10 is made up of a front and a rear wall
12a and 12a and a right and a left wall 12b and 12b. A pair of fitting parts for a
handle 74 and 74 are provided, one on the right wall 12b and the other on the left
wall 12b at positions facing each other. The fitting parts 74 are formed mainly of
pulp similarly to the molded article 10. They are integral with, or separate from,
the right and the left walls. The fitting parts 74 which are separate parts are attached
to the right and the left walls 12b and 12b by means for joining, such as an adhesive
or caulking. Totally made mainly of pulp, the molded article 10 is easy to dispose
of with no necessity to separate into parts for separate disposal.
[0086] An enlarged view of the fitting part 74 is shown in Fig. 18. Seen from the side,
the fitting part 74 has the shape of a mushroom, being composed of a columnar stem
74A and a semispherical cap 74B connected to an end of the stem 74A.
[0087] The handle 76 to be fitted to the fitting parts 74 has a U-shape. A fitting hole
78 is made through the handle 76 near each end of the U-shape at facing positions.
Each fitting hole 78 has a shape composed of a circular hole 78A and a pair of oblong
holes connecting to the circular hole 78A, the oblong holes being on the line passing
through the center of the circular hole 78A. The diameter of the circular hole 78A
is almost equal to or slightly greater than that of the cap 74B of the fitting part
74. The width of the oblong holes is almost equal to or slightly greater than that
of the diameter of the stem 74A of the fitting part 74. The handle 76 is fitted to
the molded article 10 by passing the cap 74B of the fitting part 74 of the molded
article 10 through the circular hole 78A of the fitting hole 78 of the handle 76 and
then pulling the handle 76 upward to fit the stem 74A of the fitting part 74 into
the oblong hole 78B of the fitting hole 78 of the handle 76.
[0088] The handle 76 can be of plastics as conventionally used but is preferably made mainly
of pulp similarly to the molded article 10 to exclude the necessity to dispose of
separately.
[0089] In the production of the molded article according to the present embodiment, the
fitting parts 74 can be formed by integral molding with the molded article 10 or formed
separately from the molded article 10.
[0090] In the present embodiment, the fitting parts 74 may be metallic pins instead of pulp
molded parts.
[0091] A molded article 10 according to the seventh embodiment shown in Fig. 19 is a cylindrical
bottle having a thick-walled portion 87 in its opening portion 11 in the area from
the upper edge 86 to a prescribed depth d, which is thicker than the body portion
12 and the bottom portion 13. The thick-walled portion 87 is continuous along the
circumference of the opening portion 11. For some uses of the molded article 10, the
thick-walled portion 87 may be discontinuous.
[0092] The whole opening portion 11 from the upper edge 86 to the base of the neck could
be a thick-walled portion 87, but it is sufficient for the opening portion 11 to have
the thick-walled portion 87 from its upper edge 86 to a prescribed depth d shown in
Fig. 19 as long as sufficient mechanical strength is secured. The depth d is usually
0.5 to 50 mm, preferably 5.0 to 30 mm, while dependent on the use, the shape, and
the like of the molded article.
[0093] As shown in Fig. 19, the thick-walled portion 87 projects inward. The degree of projection,
represented by the width x of the projection (see Fig. 19) in the horizontal direction
measured from the inner wall of a part having no such a thick-walled portion 87 in
the opening portion 11, is 0.5 to 5.0 mm, preferably 1.0 to 3.0 mm, which suffices
to secure the mechanical strength of the opening portion 11. Having an increased area,
the upper surface 86 of the opening portion 11 offers an increased sealing surface
area to enhance the adhesive strength to a seal, etc. when it is sealed.
[0094] Sufficient mechanical strength is secured for the opening portion 11 when the depth
d and the width x of the projection is such that d/x is from 0.1 to 100, preferably
1 to 30. The part of the opening portion 11 that is deeper than the depth d can be
tapered so that the width x of the projection gradually approaches zero as shown in
Fig. 6.
[0095] It is preferred for the upper surface 86 of the opening portion 11 to be smooth to
secure improved sealability when it is sealed with a seal, etc. Sufficient sealability
will be secured with the upper surface 86 having such smoothness as to have a center-line
average roughness (Ra) of about 50 µm or smaller and a maximum height (R
max) of about 500 µm or smaller. The upper surface 86 can be made smooth by, for example,
a post treatment such as polishing by a prescribed means after the production of the
molded article 10. Preferably, a sufficiently smooth upper surface 86 is obtained
without the above-described post treatment by producing the molded article by use
of the papermaking mold hereinafter described.
[0096] A preferred method for producing the molded article according to this embodiment
will be described by referring to Figs. 20 to 22.
[0097] The molded article 10 of the present embodiment is preferably produced by use of
a papermaking mold which comprises:
a set of splits, each having a plurality of interconnecting holes connecting the outside
and the inside, which are joined together to form a cavity in conformity to the outer
contour of an article to be molded and
a mold for creating stagnation which is to be inserted into the above-described cavity
to form a space where a slurry stagnates.
[0098] Fig. 20 shows an exploded perspective view of the mold used to produce the molded
article of the present embodiment. The mold comprises a set of splits 3 and 4 having
the same structure as the splits 3 and 4 shown in Fig. 4 except for the cavity configuration
and a mold 97 for causing stagnation (hereinafter "stagnation-making mold") which
is inserted from the outside into the cavity to form a space with the inner wall of
the cavity, in which space a slurry stagnates. The inner wall of the split 4, while
not shown in Fig. 20, has the same configuration as that of the mating split 3.
[0099] As shown in Figs. 20 and 21, the split 3 is composed of a papermaking part 91A and
a manifold part 91B. The papermaking part 91A is fitted into the manifold part 91B
to make up the split 3. With this fitting, there is formed a manifold 91C between
the papermaking part 91A and the manifold part 91B. The inner side of the papermaking
part 91A may be covered with a net of prescribed mesh. A plurality of interconnecting
holes 94, 94,... are regularly pierced through the papermaking part 91A from the inner
to the outer surfaces. These interconnecting holes 94 connect with the manifold 91C.
A plurality of suction holes 91D are also pierced in both sides of the manifold part
91B thereby to form interconnecting passageways in the split 3 which connect the outside
of the manifold part 91B and the inner surface of the papermaking part 91A.
[0100] On joining the splits 3 and 4 together, there is formed a cavity 1 in conformity
to the contour of an article to be molded as shown in Fig. 20. The part of the cavity
1 that corresponds to the opening portion 11 of the molded article (hereinafter referred
to as "the cavity part corresponding to an opening portion") has an opening open to
the outside. Into this part is inserted a wall 97B for making the slurry stagnant
(hereinafter "a slurry stagnation wall", described later) of the stagnation-making
mold 97. While not depicted, the inner side of the cavity part corresponding to the
opening portion has grooves corresponding to a screw thread.
[0101] As shown in Figs. 20 and 21, the stagnation-making mold 97 is composed of a rectangular
top plate 97A and a cylindrical slurry stagnation wall 97B hanging from approximately
the center of the lower side of the top plate 97A. The slurry stagnation wall 97B
makes a hollow cylinder which vertically pierces the stagnation-making mold 97 and
serves as a gate 97C through which a slurry is poured into the mold. The slurry stagnation
wall 97B of the stagnation-making mold 97 is inserted into the cavity part corresponding
to the opening portion, and the lower side of the top plate 97A and the upper end
of the split mold 3, 4 are brought into contact to complete the mold.
[0102] The diameter of the slurry stagnation wall 97B is smaller than that of the cavity
part corresponding to the opening portion. Therefore, with the slurry stagnation wall
97B inserted in the cavity part corresponding to the opening portion, an annular space
98 in which a slurry stagnates is formed between the inner wall of that part of the
cavity and the outer side of the slurry stagnation wall 97B.
[0103] Figs. 22(a) and (b) illustrate part of a papermaking step, one of the steps for producing
the molded article 10 by use of the above-described mold, wherein (a) is the papermaking
step, and (b) is the step of opening the mold and removing a pulp deposited body.
In Figs. 22, part of the mold is omitted from the illustration for the sake of simplicity.
[0104] As shown in Fig. 22(a), an injection pump (not shown) is started to suck up a pulp
slurry from a pulp slurry storage tank (not shown) and inject the pulp slurry under
pressure into the mold through the slurry gate 97C. Then, the cavity 1 is evacuated
by suction from the outside of the splits 3 and 4, thereby to suck up the water content
of the pulp slurry and to build up pulp fibers on the inner wall of the cavity 1.
The pulp slurry easily goes around to fill the annular space 98 formed between the
outer side of the slurry stagnation wall 98B and the inner side of the cavity part
corresponding to the opening portion and stays there, making the pulp fibers be accumulated
there more than on the other parts of the cavity 1. Since the pulp slurry is injected
into the cavity 1 under pressure, the pulp slurry pressure is equal in every part
of the cavity 1 so that the annular space 98 can sufficiently be filled with the pulp
slurry. It follows that the pulp deposited body 5 formed on the inner wall of the
cavity 1 has a larger wall thickness in its upper edge and its vicinities than in
the other portions. The thickness of the thicker portion corresponds to the breadth
of the annular space 98.
Then, the same steps as the step of inserting a pressing member and the step of
pressing and dewatering shown in Figs. 4(b) and (c) are carried out. As shown in Fig.
19, the resulting molded article 10 can have sufficiently enhanced strength in its
thick-walled portion 87 near the upper surface 86 of the opening portion 11 particularly
through the pressing and dewatering step.
[0105] After the shape of the inner wall of the cavity 1 is sufficiently transferred to
the pulp deposited body 5, and the pulp deposited body 5 is dewatered to a prescribed
water content, the pressurizing fluid in the pressing member 6 is withdrawn, and the
pressing member 6 is removed from the cavity 1 as shown in Fig. 22(b). The mold is
opened, and the pulp deposited body 5 in a wet state with a prescribed water content
is taken out. Thereafter, the pulp deposited body 5 is forwarded to the step of heat
drying in the same manner as in the method for producing the molded article of the
first embodiment to obtain the molded article 10.
[0106] As stated above, the molded article 10 thus produced has a thick-walled portion 87
in the opening portion 11 from the upper surface 86 to a prescribed depth d, which
is thicker than the body portion 12 and the bottom portion 13. In addition, the upper
surface 86 is so smooth as to exhibit sufficient adhesive strength when sealed with
a seal, etc. without being given any special post treatment.
[0107] The thick-walled portion 86 in the molded article 10 of the present embodiment can
project both inward and outward. If desired, the part of the thick-walled portion
projecting outward can serve as, for example, a projection for fitting a cap on.
[0108] A molded article 10 of the eighth embodiment which is shown in Fig. 23 has a thin
plastic layer on its outer surface 104 and inner surface 105. Such plastic layers
not only give the molded article 10 further increased strength but effectively prevent
leaks of the contents. Because the outer surface 104 and the inner surface 105 of
the molded article 10 are smooth, the plastic layers can be satisfactorily adhered
to the outer surface 104 and the inner surface 105. While the thickness of each plastic
layer is selected appropriately according to the wall thickness of the molded article
1, the kind of the contents and the like, it is usually 5 to 300 µm, particularly
10 to 200 µm, especially 20 to 100 µm. The two plastic layers may be the same or different
in thickness. The materials constituting each plastic layer include various thermoplastic
synthetic resins such as polyethylene and polypropylene, emulsion latices such as
an acrylic emulsion, and waxes such as a hydrocarbon wax.
[0109] Where, in particular, the molded article 10 is laminated with a plastic film, the
plastic is chosen from appropriate materials according to the purpose of laminating,
for example imparting water resistance or gas barrier properties. For instance, a
film of a polyolefin, e.g., polypropylene or polyethylene, a polyester, e.g., polyethylene
terephthalate or polybutylene terephthalate, polystyrene, polycarbonate, etc. can
be used. A multilayer film composed of a plurality of films made of these materials
can also be used.
[0110] A plastic layer can be formed on the inner surface of the molded article 10 by, for
example, replacing the pressing member 6 having elasticity used in the molded article
production method shown in Fig. 4 with a pressing member of bag form made of a plastic
film of polyethylene or polypropylene, etc., the plastic film having aluminum or silica
deposited thereon, the plastic film laminated with aluminum foil, etc., and the like.
After the pulp deposited body 5 is pressed by such a pressing member of bag form,
it is not taken out but remains superposed on the inner surface of the pulp deposited
body 5 thereby to form a plastic layer on the inner surface of the molded article
10.
[0111] A plastic layer can also be formed on the inner surface of the molded article 10
by replacing the elastic pressing member with a closed-end cold parison (preformed
parison) having been preheated to a predetermined temperature. The parison is inserted
into the pulp deposited body 5, and a pressurizing fluid is fed into the parison to
inflate it. The plastic film is thus adhered to the inner surface of the pulp deposited
body thereto to form a plastic layer on the inner surface of the molded article 10.
[0112] As an alternative for laminating the inner surface of the molded article 10 with
a plastic film, vacuum forming or pressure forming is also useful. The method depicted
in Fig. 24 is suitable. In this method a first vacuum chamber 130 and a second vacuum
chamber 140 are used as shown in Fig. 24(a). The first vacuum chamber 130 has an opening
131 at the top and a through-hole 132 in the side wall near the bottom. The through-hole
132 is connected to a suction means not shown. The inner shape of the cross-section
of the opening 131 is made slightly larger than the outer contour of the cross-section
of the opening portion 11 of the molded article 10. On the other hand, the second
vacuum chamber 140 has an opening 141 at the bottom. The opening 141 of the second
vacuum chamber 140 is shaped to close the opening 131 of the first vacuum chamber
130. The inner shape of the cross-section of the opening 141 is made larger than that
of the opening 131 of the first vacuum chamber 130. The upper side of the second vacuum
chamber 140 has a plurality of through-holes 142, 142..., which are connected to a
suction means not shown. A heating means 143, such as an electric heater, is provided
on the inner wall of the upper side of the second vacuum chamber 140.
[0113] The inner surface of a hollow container 1 can be laminated with a plastic film by
use of the vacuum chambers 130 and 140 as follows. As shown in Fig. 24(a), a molded
article 10 is placed in the first vacuum chamber 130 with its opening portion 11 up.
The depth of the first vacuum chamber 130 is virtually the same as the height of the
molded article 10 so that the upper opening edge of the placed molded article 10 and
that of the first vacuum chamber 130 are almost even.
[0114] In this state a stretchable plastic film 150 in its unstretched state is placed to
close the opening 131. Larger than the cross-section of the first vacuum chamber 130,
the plastic film 150 closes the opening 131 and also covers all the upper surface
of the opening 131. Subsequently, the second vacuum chamber 140 is set on the first
vacuum chamber 130 with its opening 141 facing the plastic film 150. Since the first
and the second vacuum chambers 130 and 140 are of the same shape in their cross-sections,
the plastic film 150 are held in between the periphery of the opening 131 of the first
vacuum chamber 130 and the periphery of the opening 141 of the second vacuum chamber
140. Each of the first and the second vacuum chambers 130 and 140 is thus made air-tight.
To maintain sufficient air tightness in each vacuum chamber, the two vacuum chambers
may be fastened together by a fixing means such as a metal fastener.
[0115] The second vacuum chamber 140 is then sucked by a suction means (not shown) connected
to the through-holes 142, whereby the second vacuum chamber 140 is evacuated, and
the plastic film 150 is drawn up in the second vacuum chamber 140 and stretched gradually.
On continuing evacuating the second vacuum chamber 140, the plastic film 150 is further
stretched and comes into close contact with the inner wall of the second vacuum chamber
140 as shown in Fig. 24(b). The stretching in this stage is preliminary. The stretch
ratio is decided appropriately in accordance with the shape of the molded article
10 to be laminated with the plastic film 150. In general, when the plastic film 150
is preliminarily stretched with the ratio of the surface area of the preliminarily
stretched plastic film 150 to that of the plastic film superposed on the molded article
10 (the former/the latter) being 3 to 0.7, particularly 2 to 0.9, laminating the molded
article 10 with the plastic film 150 can be accomplished with improved adhesion, and
laminating the molded article 10 having a complicated shape is carried out more easily.
The pressure (degree of vacuum) in the second vacuum chamber 140 is such that the
plastic film 150 may be preliminarily stretched to come into intimate contact with
the inner wall of the second vacuum chamber 140. While depending on the thickness
and material of the plastic film 150, the pressure is generally 40 kPa or lower, preferably
1 to 1300 Pa.
[0116] While the preliminarily stretched plastic film 150 is in intimate contact with the
inner wall of the second vacuum chamber 140, it is heated to a prescribed temperature
by the heating means 143 provided on the inner wall of the upper side of the second
vacuum chamber 140. The plastic film 150 is softened by this heating to further secure
the intimate contact of the plastic film 150 with the molded article 10 in laminating
and to further facilitate laminating the molded article 10 having a complicated shape.
For example, in using polyethylene or polypropylene having a glass transition temperature
(Tg) of room temperature (23°C) or lower as a constituent material of the plastic
film 150, the heating temperature preferably ranges from (melting point + 30)°C to
(melting point - 70)°C, particularly from (melting point + 5)°C to (melting point
- 30)°C. In using polyethylene terephthalate or polystyrene whose Tg is room temperature
or higher as a constituent material, the heating temperature preferably ranges from
(Tg + 5)°C to (Tg + 150)°C, particularly (Tg + 10)°C to (Tg + 100)°C. Within these
ranges, the plastic film 150 can be superposed with closer contact on the molded article
10 without tearing. Where the plastic film 150 is made of two or more kinds of materials,
the glass transition temperature of the material having the lowest glass transition
temperature is taken as the above-described glass transition temperature.
[0117] While the plastic film 150 being in close contact with the inner wall of the second
vacuum chamber 140 by suction, the first vacuum chamber 130 is evacuated by a suction
means (not shown) connected to the through-hole 132. Since there is a gap between
the inner wall of the opening 131 of the first vacuum chamber 130 and the outer wall
of the opening portion 11 of the molded article 10, the inside and the outside of
the molded article 10 connect with each other to let gas flow therethrough. Therefore,
the above evacuation by suction creates a vacuum in the first vacuum chamber 130,
i.e., the inside and the outside of the molded article 10 similarly to the inside
of the second vacuum chamber 140. In this state, the plastic film 150, which has been
in intimate contact with the inner wall of the second vacuum chamber 140, is not drawn
into the first vacuum chamber 130 by the evacuation of the first vacuum chamber 130.
While not particularly limiting, a preferred pressure (degree of vacuum) of the first
vacuum chamber 130 is usually 40 kPa or lower, particularly 1 to 1300 Pa.
[0118] Then, the evacuation of the second vacuum chamber 140 is stopped. Further, the vacuum
in the second vacuum chamber 140 is broken and, at the same time, pressure is applied
into the second vacuum chamber 140 to a predetermined pressure. These operations can
be performed instantaneously by switching a three-way valve, etc. Because the first
vacuum chamber 130 is in the evacuated state, the plastic film 150 which has been
in intimate contact with the inner wall of the second vacuum chamber 140 is instantaneously
drawn and stretched toward the inside of the first vacuum chamber 130, i.e., the inside
of the molded article 10 in the present embodiment, whereby the inner surface of the
molded article 10 is laminated with the plastic film 150 with intimate adhesion as
shown in Fig. 24(c). In other words, the plastic film 150 is stretched in the direction
opposite to the direction of preliminary stretching. Having been heated to a predetermined
temperature until the vacuum of the second vacuum chamber 140 is broken, the plastic
film 150 can be stretched and adhered to the molded article 10 extremely smoothly,
being effectively prevented from, e.g., tearing on stretching. Pressure application
into the second vacuum chamber 140 is carried out with a prescribed pressurizing fluid,
conveniently air. In order for the plastic film 150 to be brought into intimate contact
with the molded article 10 without tearing, the pressure to be applied is preferably
100 to 3000 Pa, particularly 200 to 1000 Pa.
[0119] Where laminating the molded article 10 with the plastic film 150 is conducted with
the molded article 10 being heated to a predetermined temperature, the plastic film
150 can be superposed on the molded article 10 with further improved adhesion while
being prevented from tearing more effectively. This is because satisfactory stretchability
of the plastic film 150 is maintained during the laminating. The molded article 10
can be heated by, for example, a prescribed heating means provided on the inner side
of the side wall of the first vacuum chamber 130. A preferred heating temperature
of the molded article 10 is from 40 to 150°C for preventing re-shrinkage of the plastic
film 150 and securing the production efficiency.
[0120] After the plastic film 150 is superposed, the evacuation by suction of the first
vacuum chamber 130 is stopped, and the inner pressure is increased to atmospheric
pressure. The second vacuum chamber 140 is then removed, and the molded article 10
laminated with the plastic film 150 is taken out of the first vacuum chamber 130.
At this time point, there remains the free plastic film 150 around the opening portion
of the molded article 10, which is trimmed to give the molded article 10 shown in
Fig. 24(d) which has the inner surface thereof and the upper edge of its opening portion
intimately laminated with the plastic film 150.
[0121] According to the above-mentioned method of production, the plastic film 150 can be
superposed on the molded article 10 with good adhesion without tearing even if it
is stretched at a stretch ratio as high as 4 to 10, the stretch ratio of the plastic
film 150 being defined as a ratio of the surface area of the plastic film 150 superposed
on the molded article 10 and the opening area of the opening 131 of the first vacuum
chamber 130 (the former/the latter).
[0122] The above production method has a merit that the molded article 10 can be laminated
with a film irrespective of whether or not it has air permeability. Further, because
it is not necessary to evacuate through the wall of the molded article 10, the time
required for evacuation by suction can greatly be shortened as compared with conventional
vacuum forming and the like to markedly improved the productivity. Furthermore, the
molded article 10 does not suffer from deformation by evacuation, it is not necessary
to use a reinforcing mold as in conventional vacuum forming and the like, which leads
to production cost reduction.
[0123] Where the above-described laminating method is adopted, it is preferred to use a
stretchable film as the plastic film. In this case, it is preferred for the plastic
film to have a thickness of about 5 to 200 µm, particularly about 20 to 100 µm, after
laminating so as to impart desired characteristics such as water resistance and gas
barrier properties to the molded article. The thickness before laminating, while varying
depending on the desired thickness after laminating, the stretch ratio, etc., preferably
ranges from about 50 to 1000 µm, particularly about 100 to 500 µm, from the viewpoint
of handling properties during the production and the plastic film heating efficiency.
[0124] In carrying out laminating with the plastic film 150 shown in Fig. 24, where the
molded article 10 is placed upside down (the opening portion 11 of the molded article
10 facing downward), the outer surface of the molded article 10 can be laminated with
the plastic film 150. It is possible to laminate both the inner surface and the outer
surface (except the bottom surface) of the molded article 10 with a single plastic
film at the same time by making the opening 131 of the first vacuum chamber 130 extremely
larger than the outer contour of the opening portion 11 of the molded article 10 to
provide a wide gap between the opening 131 of the first vacuum chamber 130 and the
opening portion 11 of the molded article 10. In this case, another film can be set
between the bottom portion of the molded article 10 and the inner wall of the bottom
of the first vacuum chamber 130 so that the inner and the outer surfaces, including
the bottom surface, of the molded article 10 may be laminated with the two films simultaneously.
[0125] When the molded article having the inner and/or the outer surfaces thereof laminated
with the plastic film is left to stand at 60°C for 30 minutes, the plastic film preferably
has a shrinkage percentage of 30% or less, particularly 10% or less.
[0126] If the shrinkage percentage exceeds 30%, there is a fear that the plastic film peels
in parts and that tearing of the molded article 10 initiates from the parts where
the plastic film peels. That is, long-term storage stability reduces. The shrinkage
percentage is obtained from the distance between two arbitrary points on the plastic
film-laminated surface of a molded article measured before and after the storage under
the above-described conditions according to formula: (1 - distance before storage/distance
after storage) x 100. The shrinkage percentage can be made 30% or less by, for example,
heating the plastic film-laminated molded article to the glass transition point of
the plastic film or a higher temperature, followed by slow cooling. Where the plastic
film is a laminate comprising two or more plastic materials, the heating is at or
above the glass transition point of the plastic material having the lowest glass transition
point.
[0127] There is another embodiment for forming a plastic layer on the outer and/or the inner
surfaces of a molded article, which comprises powder coating the outer and/or the
inner surfaces of the molded article to form a plastic layer(s).
[0128] If a solvent- or water-based coating is used for plastic layer formation, the plastic
layer tends to form micropores while the solvent or the like evaporates, resulting
in a failure to manifest sufficient gas barrier properties (shielding against water
or oxygen). There is also a fear that the solvent, etc. may deform the molded article.
A plastic layer formed by powder coating is free from these disadvantages, providing
a molded article with sufficient gas barrier properties.
[0129] Powder which can be used for powder coating includes powder of olefin resins, polyester
resins, epoxy resins, acrylic resins, etc. The powder can consist solely of the resin
or, if necessary, it can be colored by addition of various pigments. In addition,
conventional additives known to be useful in coating compositions can be used with
no particular restriction. Such additives include leveling agents, e.g., acrylate
polymers and silicone resins, and pinhole preventing agents, e.g., benzoin. These
additives are added in an amount of about 0.1 to 5 parts by weight each per 100 parts
by weight of the resin. The total thickness of the plastic layer(s) (the total of
the plastic layers formed on the outer and the inner surfaces of a molded article)
is decided appropriately according to the use of the molded article, the wall thickness,
the kind of the contents, and the like and is usually from 50 to 600 µm. From the
standpoint of water vapor permeability, productivity, and cost, a preferred total
thickness is 100 to 400 µm.
[0130] Powder coating can be carried out with a coating gun, which has at the tip thereof
a nozzle equipped with a corona electrode for forcibly charging the powder simultaneously
with ejecting a powder coating. The powder coating ejected and charged simultaneously
adheres to the surface to be coated, i.e., the outer and/or the inner surfaces of
the molded article by electrostatic force. To secure the adhesion, it is preferred
to apply a voltage of -10 to -80 kV, particularly -40 to -70 kV, to the powder coating.
[0131] Application of the powder coating is followed by a baking step in which the applied
powder coating is melted and hardened to form a plastic layer. A baking oven capable
of heating to a prescribed temperature is used for baking. From the standpoint of
productivity, smoothness of the coating film, and prevention of scorching, the baking
is carried out at a temperature of 70 to 230°C, particularly 140 to 200°C, for a period
of 1 to 20 minutes, particularly 5 to 20 minutes.
[0132] There is still another embodiment for forming a plastic layer on the outer and/or
the inner surfaces of a molded article, which comprises applying a resin solution
or a resin emulsion to the outer and/or the inner surfaces of a molded article to
form a plastic layer. In this embodiment, the plastic layer preferably has a thickness
of 5 to 300 µm, particularly 20 to 150 µm, and the ratio of the thickness of the plastic
layer to the thickness of the molded article (the former/the latter) is preferably
1/2 to 1/100, particularly 1/5 to 1/50.
[0133] If the thickness of the plastic layer is smaller than 5 µm, the waterproofing and
water vapor proofing effect tends to be insufficient for giving the contents sufficient
storage stability. If the thickness exceeds 300 µm, the plastic layer needs time for
drying, and the coating tends to sag while applied, resulting in such defects as unevenness
of thickness. The thickness of the plastic layer can be measured by microscopic observation
of the section of the molded article. The molded article according to this embodiment
has a clear boundary between the pulp fiber which constitutes the molded article and
the resin which constitutes the plastic layer unlike an article of which the plastic
layer is formed by coating a molded article with a coating composition in a conventional
manner. That is, in a conventional method, an aqueous solution of a polymer penetrates
into an undried molded article so that the boundary between the pulp fiber and the
polymer is indefinite, whereas the molded article of the present embodiment is less
pervious to the resin to make the boundary definite. As a result, the molded article
can be made waterproof and water vapor proof with a smaller amount of the resin than
needed conventionally, and the pulp fiber can be disintegrated more easily when recycled.
[0134] If the thickness ratio of the plastic layer to the molded article exceeds 1/2, disintegrability
in recycling is poor. If it is less than 1/100, sufficient waterproofness and water
vapor proofness cannot be obtained. The thickness of the molded article is appropriately
decided according to the use, etc. so that the above ratio may fall within the range
of from 1/2 to 1/100. The thickness is preferably 100 to 3000 µm, still preferably
500 to 2000 µm.
[0135] The resin used in the coating composition for forming a plastic layer includes acrylic
resins, styrene-acrylic resins, ethylene-vinyl acetate resins, styrene-butadiene rubber
resins, polyvinyl alcohol resins, vinylidene chloride resins, waxes, fluorine resins,
silicone resins, and copolymers and polyblends of these resins.
[0136] In order to control penetration of the coating composition into the molded article,
it is preferred for the molded article to have a void of 30 to 70%, particularly 40
to 60%. The void is calculated from the following formula (1). In formula (1), the
density of a molded article is calculated from the weight and the thickness of a piece
cut out of the molded article, and the density of the material which constitutes the
molded article is calculated from the proportions of pulp fiber and other components
and the density.

[0137] With too small the void, the molded article may be too impervious to the coating
composition, tending to have reduced adhesion to the plastic layer. Taking the penetrability
of the coating composition into consideration, it is preferred for the molded article
to have a Cobb's water absorptiveness (JIS P8140) of 5 to 600 g/(m
2·2 min), particularly 10 to 200 g/(m
2·2 min).
[0138] The coating composition is applied by spraying with a prescribed spraying means after
the wet pulp deposited body 5 obtained in Fig. 4(b) is preliminarily dried to a prescribed
water content, e.g., about 0.1 to 25% by weight. The void of the molded article being
within the above range, the coating composition hardly penetrates into the molded
article. As a result, most of the coating composition remains on the surface of the
molded article, succeeding in manifesting sufficient waterproofness and water vapor
proofness with a smaller amount of the coating composition than conventionally required.
In addition, reduction in disintegrability of the pulp fiber in recycling is avoided.
In using an emulsion as a coating composition, it is desirable to use an emulsion
having a resin particle size of about 0.01 to 10 µm for controlling penetration of
the emulsion into the molded article.
[0139] Yet another embodiment for forming a plastic layer on the outer surface of the molded
article 10 comprises covering the outer surface of the molded article 10 with a shrink
film with or without prescribed letters, figures, symbols, etc. printed thereon. The
shrink film covers the entire outer surface of the molded article 10 so that penetration
of water or oxygen from the outside into the inside can be prevented thereby to prevent
reduction in paper strength of the molded article 10 and to prevent mold development
in the contents. Further, reduction in quality of the contents due to penetration
of water or oxygen can also be prevented. Furthermore, the strength of the molded
article 10 is further enhanced, and the contents are effectively prevented from leaking.
[0140] According to the kind of the contents, the shrink film does not need to cover the
entire outer surface of the molded article 10 as shown in Fig. 25. The embodiment
shown in Fig. 25 is especially effective where the contents are such that generate
gas on moisture absorption and the like. The shrink film 151 covers not all the outer
surface of the molded article 10 but the area up to the height of or above the upper
level of contents 152 and below the top of the container (the space between the upper
level of the contents 152 and the top of the container is called a head space). In
case when the contents react due to moisture absorption, etc. to generate gas, and
the gas is accumulated in the head space, the gas has its escape blocked if the outer
surface around the head space is covered with the shrink film 151. It follows that
the molded article 10 is inflated and deformed, which makes the molded article 10
instable and, in the worst case, ends in a burst. According to the wrapping mode shown
in Fig. 25, such a phenomenon does not occur because the generated gas is allowed
to escape outside through the wall around the head space of the molded article 10.
[0141] The wrapping mode of Fig. 25 also has a merit that the shrink film can be saved.
It may be conceivable that water or oxygen can enter through the wall around the head
space of the molded article 10. Even if it happens, the contact of water or oxygen
with the contents is indirect as mediated by the head space. This indirect contact
of water or oxygen is far slower than the direct content of water or oxygen with the
contents through the wall of the molded article 10 in view of material transfer. Accordingly
only if the molded article 10 is wrapped up to the height of the contents, i.e., only
if the direct contact through the wall of the molded article 10 is avoided, penetration
of water or oxygen through the wall around the head space of the molded article 10
is not so problematical.
[0142] The shrink film 151 comprises a film of an olefin resin, a polyester resin, etc.
For example, polyethylene terephthalate (PET), oriented polystyrene (OPS), etc. are
useful as a material having good low-temperature shrinkability and high stiffness.
For shrink packaging a product all over (overwrapping), polypropylene (PP), polyethylene
(PE), etc. are useful as a thin and well-stretchable material. The above-described
materials of shrink films comprise a uniaxially or biaxially stretched film having
a single-layer or multilayer structure. Taking shrink finish, dimensional stability,
and strength into consideration, it is desirable to choose a material having a heat
shrinkage percentage (JIS Z1709) of 40% or more, a spontaneous shrinkage percentage
(40%, 7 days) of 2% or less, a tensile strength of 20 x 10
6 Pa or more in the direction of shrinkage, and an elongation of 50% or more. The thickness
of the shrink film 151, which is appropriately selected according to the use of the
molded article 10 covered with the shrink film 151, the wall thickness of the molded
article 10, the kind of the contents, and the like, is usually 10 to 150 µm, particularly
30 to 70 µm.
[0143] The molded article 10 having the outer surface thereof covered with the shrink film
has an oxygen permeability of 500 cm
3/(m
2·hr·atm) or less, particularly 100 cm
3/(m
2·hr·atm) or less. It prevents the inside thereof from getting into a peroxidized state
thereby to prevent reduction or deterioration of the quality of the contents. The
oxygen permeability is measured according to the method specified in JIS K7126.
[0144] The molded article having the outer surface thereof covered with a shrink film is
preferably produced by surrounding the molded article having a water content of 5
to 35% by weight by the shrink film and applying microwaves to shrink the shrink film
into intimate contact with the molded article and, at the same time, to dry the molded
article.
[0145] As shown in Fig. 26(a), the entire outer surface of a molded article 10 is surrounded
by a shrink film 151. It is preferred to use the molded article 10 produced by the
method of Fig. 4(d) which has a prescribed water content. The shrink film is prepared
by making a sheet into a cylinder, sealing one end of the cylinder in the form of
an arch (generally called R sealing), and cutting the other end. In this state, the
gap between the body and the bottom portions and the shrink film is not so wide, while
the gap between the opening portion and the shrink film is relatively wide.
[0146] An overcover 154 having a lid part 153 having a down-wall hanging from its periphery
is put over both the opening portion of the molded article 10 and the upper part of
the shrink film that surrounds the opening portion. The lid part 53 including the
down-wall is capable of generating heat on irradiation with microwaves. The gap between
the inner side of the down-wall and the shrink film is preferably as small as possible.
[0147] In this state, microwaves are applied, whereupon the water content of the molded
article 10 is heated to generate heat, and the shrink film shrinks to tightly adhere
to the molded article 10 by the generated heat. At the same time, the water content
is removed from the molded article 10 to finally dry the molded article. In other
words, this method can achieve the two steps - shrinking the shrink film 151 and finally
drying the molded article - in a single operation of microwaves application.
[0148] On being irradiated with microwaves, not only the molded article 10 but the lid part
153 of the overcover 154 generate heat, with which the shrink film, particularly of
the area around the opening portion of the molded article 10, shrinks to reduce the
gap between the shrink film and the outer surface of the opening portion. Thus, the
heat generated from the opening portion itself is added to the shrink film to accelerate
the shrinkage of the shrink film. As a result, shrinkage around the opening portion
that is not easy due to the diameter difference from the other portions can be achieved
very easily. Additionally, the shrink film after shrinkage has improved appearance.
Thus, shrink wrapping by the use of the overcover 154 is effective in case where the
molded article has different diameters from its opening portion to the bottom portion.
Where the opening portion has a smaller diameter than the body portion, it is particularly
effective where the diameter of the opening portion is not more than 50% of that of
the body portion.
[0149] As described above, the lid part 153 of the overcover 154 is capable of generating
heat on microwaves application. The lid part 153 is preferably made of water-containing
wood, paper, sponge or nonwoven fabric, etc., taking into consideration ease in shaping
in conformity with the outer contour of a molded article, good heat generation efficiency,
satisfactory properties of covering a shrink film, and satisfactory operating properties.
The shape of the lid part 153 is not particularly limited as long as the shrink film
around the opening portion of the molded article 10 can be surrounded thereby.
[0150] The wavelength of the microwaves applied is generally 300 MHz to 300 GHz. A wavelength
providing the highest heat generation efficiency is selected appropriately.
[0151] The molded article 10 thus covered with the shrink film is then filled with the contents.
Depending on the kind of the contents, filling the molded article 10 which is preliminarily
dried with the contents may be followed by covering with the shrink film.
[0152] The present invention is not limited to the above-described embodiments, and various
modifications can be made therein. The steps, apparatus, elements and the like used
in each of the above-described embodiments are interchangeable with each other. While
the second to eighth embodiments have been described as embodiments of the first aspect
of the invention, they shall apply the second aspect. The molds used in the present
invention can be composed of a set of two or three or more splits in accordance with
the shape of articles to be molded. The same applies to the heating molds.
Industrial Applicability:
[0153] The present invention provides a molded article made mainly of pulp the side walls
of which have a large angle to the ground and which has a large depth. The present
invention also provides a molded article made mainly of pulp which involves no reduction
in strength, has a satisfactory appearance, and has a depression or a projection of
prescribed shape around its opening or body portions. These molded articles can be
produced at a low cost. Besides, they can be recycled or incinerated after use, which
leads to reduction of waste.