U.S. patent application number 11/152089 was filed with the patent office on 2005-12-22 for battery package and method for producing the same.
This patent application is currently assigned to MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.. Invention is credited to Kumakura, Katsuhiko, Tada, Futoshi, Uemura, Kinji, Umeda, Tozo.
Application Number | 20050281967 11/152089 |
Document ID | / |
Family ID | 35480917 |
Filed Date | 2005-12-22 |
United States Patent
Application |
20050281967 |
Kind Code |
A1 |
Tada, Futoshi ; et
al. |
December 22, 2005 |
Battery package and method for producing the same
Abstract
The present invention provides a battery package excellent in
strength, impact resistance and transparency, wherein main
components thereof are all made of a biodegradable resin by vacuum
forming. The battery package includes a base and a container
composed of a drawn sheet of biodegradable aliphatic polyester. The
drawn sheet is made of a composition containing a polylactic
polymer and at least one of polybutylene succinate and
polycaprolactone.
Inventors: |
Tada, Futoshi; (Osaka,
JP) ; Kumakura, Katsuhiko; (Kyoto, JP) ;
Umeda, Tozo; (Osaka, JP) ; Uemura, Kinji;
(Osaka, JP) |
Correspondence
Address: |
MCDERMOTT WILL & EMERY LLP
600 13TH STREET, N.W.
WASHINGTON
DC
20005-3096
US
|
Assignee: |
MATSUSHITA ELECTRIC INDUSTRIAL CO.,
LTD.
|
Family ID: |
35480917 |
Appl. No.: |
11/152089 |
Filed: |
June 15, 2005 |
Current U.S.
Class: |
428/34.1 |
Current CPC
Class: |
B65D 2585/88 20130101;
Y02W 90/13 20150501; Y02W 90/10 20150501; B65D 75/366 20130101;
Y02W 90/12 20150501; B65D 2575/363 20130101; Y10T 428/13
20150115 |
Class at
Publication: |
428/034.1 |
International
Class: |
B65D 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2004 |
JP |
2004-178531 |
Claims
1. A battery package comprising a base and a container including a
drawn sheet of biodegradable aliphatic polyester, wherein said
drawn sheet comprises a composition containing a polylactic polymer
and either of polybutylene succinate and polycaprolactone.
2. The battery package in accordance with claim 1, wherein said
base comprises a biodegradable aliphatic polyester.
3. The battery package in accordance with claim 1, further
comprising a laminate layer comprising a biodegradable aliphatic
polyester arranged between said base and said container.
4. The battery package in accordance with claim 2, wherein said
biodegradable aliphatic polyester constituting said base is a
polylactic polymer.
5. The battery package in accordance with claim 1, wherein said
base has a first printing layer, an anti-offset layer and a second
printing layer laminated in this order on the surface thereof
opposite to the container-side surface.
6. A method for producing a battery package comprising the steps
of: forming a drawn sheet of biodegradable aliphatic polyester into
a container having a holder portion by vacuum forming; and
integrating said container with a base comprising a drawn sheet of
biodegradable aliphatic polyester to obtain a battery package.
7. The method for producing a battery package in accordance with
claim 6, wherein said drawn sheet comprises a composition
containing a polylactic polymer and either of polybutylene
succinate and polycaprolactone.
8. The method for producing a battery package in accordance with
claim 6, further comprising the steps of: bonding a laminate layer
comprising a drawn sheet of biodegradable aliphatic polyester to
said base to obtain a bonded product; and heat sealing said
laminate layer and said container to integrate said base and said
container.
9. The method for producing a battery package in accordance with
claim 6, further comprising the steps of: bending the peripheral
edges of said container on the opposite side of said holder portion
to form folds; and inserting said base in said folds to integrate
said container and said base.
10. The method for producing a battery package in accordance with
claim 6, wherein said base comprises a biodegradable aliphatic
polyester.
11. The method for producing a battery package in accordance with
claim 10, wherein said biodegradable aliphatic polyester
constituting said base is a polylactic polymer.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a battery package and a
method for producing the same.
BACKGROUND OF THE INVENTION
[0002] Thermoplastic resins such as polyethylene, polyvinyl
chloride, polystyrene and polyethylene terephthalate (PET) have
been used as materials for product packages. These resins, however,
are chemically stable, and therefore do not decompose under natural
environment. Instead, they remain physically and chemically
unaffected.
[0003] Accordingly, the use of such materials is accompanied by the
problem that it may lead to pollution of the environment and more
landfill sites. Currently, battery packages, in particular, are
mostly made of PET, and they are disposed of with other wastes
while the batteries are collected.
[0004] In order to solve the above problems, as environmentally
friendly resins, biodegradable resins capable of decomposing and
disappearing with time under natural environment have been
developed, and some plastic bags and containers are made therefrom.
Examples of the biodegradable resins include aliphatic polyester,
modified polyvinyl alcohol (PVA), cellulose ester compounds and
modified starch. Among them, the aliphatic polyester is
environmentally preferred because alcohol and carboxylic acid
generated therefrom during the decomposition are extremely less
toxic.
[0005] The biodegradable resins have been used in relatively large
molded products such as a film as disclosed by Japanese Laid-Open
Patent Publication No. Hei 10-100353, a document folder as
disclosed by Japanese Laid-Open Patent Publication No. 2001-130183,
and food trays. However, due to their brittleness, it has been
difficult to mold or form the resin into an extremely compact shape
such as a battery package. Moreover, because battery packages,
which accommodate batteries that are relatively heavy, are required
to have sufficient strength, impact resistance and transparency, it
has been difficult to obtain a molded product that satisfies all
these requirements.
[0006] Under the circumstances, in Japanese Laid-Open Patent
Publication No. 2004-348976 (Japanese Patent Application No.
2003-139093), the present inventors have proposed to form a drawn
sheet of biodegradable resin into a container by means of
vacuum/pressure forming. However, because strong force is applied
during the vacuum/pressure forming, the resulting container might
have a slightly thin portion, resulting in a lower strength, and
the productivity tends to be low.
[0007] In view of the above, an object of the present invention is
to provide a battery package excellent in strength, impact
resistance and transparency produced by vacuum/pressure forming
method using a biodegradable resin. Another object of the present
invention is to provide an environmentally friendly battery package
whose main components are all made of a biodegradable resin.
BRIEF SUMMARY OF THE INVENTION
[0008] The present invention relates to a battery package
comprising a base and a container including a drawn sheet of
biodegradable aliphatic polyester, wherein the drawn sheet
comprises a composition containing a polylactic polymer and either
of polybutylene succinate and polycaprolactone.
[0009] It is effective that the base be made of a biodegradable
aliphatic polyester. It is preferred that the biodegradable
aliphatic polyester be a polylactic polymer.
[0010] Further, a laminate layer made of a biodegradable aliphatic
polyester is preferably arranged between the base and the
container.
[0011] The base preferably has a first printing layer, an
anti-offset layer and a second printing layer laminated in this
order on the surface of the base opposite to the container-side
surface.
[0012] The present invention further provides a method for
producing a battery package comprising the steps of: forming a
drawn sheet of biodegradable aliphatic polyester into a container
having a holder portion by vacuum forming; and integrating the
container with a base made of a drawn sheet of biodegradable
aliphatic polyester to obtain a battery package.
[0013] In this case, it is preferred to bond a laminate layer made
of a drawn sheet of biodegradable aliphatic polyester to the base
to obtain a bonded product, and to heat seal (melt) the laminate
layer and the container to integrate the base and the
container.
[0014] Alternatively, it is also preferred to bend the peripheral
edges of the container on the opposite side of the holder portion
to form folds, and to insert the base in the folds to integrate the
container and the base.
[0015] According to the present invention, a battery package whose
main components are all made of a biodegradable resin that exhibits
excellent strength, excellent impact resistance and excellent
transparency can be produced by a conventional vacuum molding
(forming).
[0016] While the novel features of the invention are set forth
particularly in the appended claims, the invention, both as to
organization and content, will be better understood and
appreciated, along with other objects and features thereof, from
the following detailed description taken in conjunction with the
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0017] FIG. 1 is an exploded perspective view schematically
illustrating an embodiment of a battery package according to the
present invention.
[0018] FIG. 2 is an exploded perspective view schematically
illustrating another embodiment of a battery package according to
the present invention.
[0019] FIG. 3 is a flowchart illustrating the major steps of a
first embodiment of a method for producing a battery package
according to the present invention.
[0020] FIG. 4 is a flowchart illustrating the major steps of a
second embodiment of a method for producing a battery package
according to the present invention.
[0021] FIG. 5 is a flowchart illustrating the steps of a method for
producing a battery package according to EXAMPLE of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] (1) Battery Package
[0023] The present invention relates to a battery package including
a base and a container, the container being made of a drawn sheet
of biodegradable aliphatic polyester, characterized in that the
drawn sheet is made of a resin composition containing a polylactic
polymer and either of polybutylene succinate and
polycaprolactone.
[0024] In view of the problems encountered in conventional
techniques, the present inventors vigorously conducted experiments
and analyzed the results regarding the molding/forming of
biodegradable resins and the obtained products. As a result, they
found that the addition of a softening agent, polybutylene
succinate or polycaprolactone, to a polylactic polymer achieves the
production of a battery package by a conventional vacuum molding
method in which a biodegradable resin is not used. Based on this
finding, the present invention has been accomplished.
[0025] FIG. 1 is an exploded perspective view schematically
illustrating an embodiment of a battery package according to the
present invention.
[0026] A battery package 1 shown in FIG. 1 is composed of a base 2
and a transparent container 3. A battery pack 4 is accommodated in
a holder portion 3a of the container 3. On the surface of the base
2 facing the container 3 is given a certain print, and then a
laminate layer (not shown in the drawing) is further formed.
[0027] A brim 3b of the container 3 and the laminate layer is then
bonded by, for example, heat sealing to integrate the base 2 and
the container 3. The base 2 may have a hanging aperture 2a so that
the battery package 1 can be hanged on a sale shelf for display. In
a conventional battery package, backing paper is used instead of
the base 2.
[0028] FIG. 2 is an exploded perspective view schematically
illustrating another embodiment of a battery package according to
the present invention.
[0029] A battery package 11 shown in FIG. 2 is composed of a base
12 and a transparent container 13. A battery pack 14 is
accommodated in a holder portion 13a of the container 13. In a
second embodiment, a certain print is given on the surface of the
base 12 facing the container 13, but the laminate layer may be
omitted.
[0030] Instead of not forming a laminate layer, a portion of the
container 13 corresponding to the brim 3b in FIG. 1 is folded to
the opposite side to the holder portion 13a to form folds 13b, 13c
and 13d. In other words, the periphery of the container 13 is
folded by 180 degrees on the base 12 side to form the folds. Along
the alternate long and short dash lines shown in FIG. 2, the base
12 is slid into the folds 13b and 13d from the edges thereof in the
direction of an arrow X. When the base 12 reaches the fold 13c, the
base 12 and the container 13 are integrated.
[0031] Since the base 12 is merely inserted in the folds 13b, 13c
and 13d of the container 13, the base 12 is preferably fixed with
the folds 13b, 13c and 13d. There is no specific limitation on the
means for fixing them, and any means can be used. For example, they
may be fixed by means of heat sealing, an adhesive or a
stapler.
[0032] Similar to the first embodiment, the base 12 may have a
hanging aperture 12a so that the battery package 11 can be hanged
on a sales shelf for display.
[0033] In the battery packages 1 and 11 shown in FIGS. 1 and 2, it
is at least required that the container 3, 13 is transparent so
that the design printed on the outer jacket of the batteries in the
battery pack 4, 14 can be observed by a user or a customer. The
base 2, 12 facing the container 3, 13, may also be transparent,
though a certain print is given to the surfaces of the base 2,
12.
[0034] In the battery packages shown in FIGS. 1 and 2, printing
layers are usually formed on the surface of the base 2, 12 facing
the container 3, 13 (first surface) and the surface opposite to the
first surface (second surface), respectively.
[0035] In the present invention, only the second surface may have a
first printing layer, an anti-offset layer and a second printing
layer formed thereon in this order.
[0036] Examples of the biodegradable resin usable in the present
invention include aliphatic polyester, modified polyvinyl alcohol
(PVA), cellulose ester compounds and modified starch. Among them,
the aliphatic polyester is environmentally preferred because
alcohol and carboxylic acid generated therefrom during
decomposition are extremely less toxic.
[0037] Examples of the aliphatic polyester include polymers
produced by microorganism-mediated processes such as a
hydroxybutyric acid-valeric acid polymer, synthetic polymers such
as polycaprolactone and an aliphatic dicarboxylic acid-aliphatic
diol condensate and semisynthetic polymers such as polylactic
polymers.
[0038] From the viewpoint of excellent transparency, stiffness,
heat resistance and processability, the polylactic polymers are
preferably used. The polylactic polymer may be a homopolymer of
L-lactic acid and/or D-lactic acid. Alternatively, it may be a
copolymer or a mixture (or a polymer alloy) with other
hydroxycarboxylic acids as long as its biodegradability is not
impaired.
[0039] Examples of other hydroxycarboxylic acids include glycolic
acid, 3-hydroxybutylic acid, 4-hydroxybutylic acid,
3-hydroxyvaleric acid, 4-hydroxyvaleric acid and 6-hydroxycaproic
acid.
[0040] The polylactic polymer, a preferred biodegradable resin,
preferably has a weight-average molecular weight of 50,000 to
100,000. If the weight-average molecular weight is less than
50,000, practical physical properties will hardly be exhibited.
Conversely, if the weight-average molecular weight is higher than
100,000, melt viscosity will be too high, resulting in poor
moldability.
[0041] The polylactic polymer has a high glass transition point and
high crystallinity, and it has characteristics similar to those of
polyethylene terephthalate (PET). Further, a film made of
polylactic acid can be uniaxially or biaxially drawn (stretched).
The resulting drawn sheet, in which molecules are oriented, is low
in brittleness, hard to crack and extremely favorable in strength.
Moreover, the polylactic polymer film can be formed by extrusion
casting, which ensures transparency of the film. In the present
invention, a drawn sheet is preferably used as a material to
produce a container particularly by vacuum forming, which will be
described later.
[0042] A raw material for the polylactic polymer may be corn.
Starch is separated from corn and then converted into sugar. Lactic
acid is then obtained by lactic acid fermentation, which is
converted into lactide, and then polymerized into polylactic acid.
As just described, the polylactic polymer can be made without using
petroleum materials. Therefore, according to the present invention,
the final resulting battery package as well as the preparation
process of the raw material are environmentally friendly.
[0043] In the present invention, the drawn sheet is produced from a
resin composition obtained by mixing the polylactic acid with a
softening agent. When the drawn sheet is molded from only the
polylactic polymer, the molding has to be performed at a relatively
low temperature so as to prevent the sheet from being brittle. For
this reason, not vacuum forming, but vacuum/pressure forming is
considered as a preferred method for producing the drawn sheet.
Vacuum/pressure forming, however, blasts strong force onto the
drawn sheet, reducing the strength of the thin portion of the
sheet, which could decrease the productivity.
[0044] In view of the above, the present invention uses a resin
composition obtained by adding a softening agent such as
polybutylene succinate or polycaprolactone to the polylactic
polymer so that the container can be formed from the drawn sheet by
vacuum forming even when polylactic polymer is used.
[0045] In this case, the mixing ratio between the polylactic
polymer and the softening agent is not specifically limited as long
as the drawn sheet can be molded into the container by vacuum
forming. Because the softening agent is milky white, the ratio
should be in the range where the transparency of the container is
not impaired.
[0046] Specifically, the mixing ratio can be appropriately adjusted
according to the molding conditions such as the strength of the
container (low brittleness, resistance to cracking), tolerance to
thinness of the side surfaces of the container, temperature, degree
of vacuum, and processing speed.
[0047] The resin composition may further contain other polymer
materials as long as the effect of the present invention is not
impaired. Additionally, for the purpose of adjusting the physical
properties and processability, it may further contain a
plasticizer, a lubricant, an inorganic filler, an ultraviolet
absorber, a heat stabilizer, a light stabilizer, a light absorber,
a coloring agent, a pigment or/and a modifier.
[0048] The reason why the drawn sheet is used will be explained
below.
[0049] Because battery packages are required to have a relatively
finely shaped holder portion with corners designed to fit the
battery, moldability as well as transparency is required.
Biodegradable resins are brittle, and thus when a biodegradable
resin sheet is molded under conventional conditions, cracks may
occur.
[0050] In order to solve the problem, the present invention uses a
drawn biodegradable resin sheet for the production of the
container. The drawing (stretching) process improves the
brittleness and strength of the resulting sheet, and thus a
container resistant to cracking can be obtained. A biaxially drawn
sheet is more preferred than a uniaxially drawn sheet because a
biaxially drawn sheet has higher strength.
[0051] Although the drawn sheet has higher strength than an undrawn
sheet, it is slightly poor in processability. Accordingly, it is
difficult to mold the drawn biodegradable resin sheet into the
container by vacuum forming or the like under the same conditions
as used when molding a package from a commonly used thermoplastic
resin. In view of this, in the present invention, the softening
agent described above is used, and the drawn sheet is molded into
the container by vacuum forming.
[0052] The drawn sheet preferably has a tensile strength (breaking
strength) of 40 to 90 MPa. When the tensile strength is less than
40 MPa, sufficient strength to carry the battery cannot be
obtained. Conversely, when the tensile strength is greater than 90
MPa, the sheet strength will be too high, decreasing moldability
and transparency of the sheet. Particularly preferred is 60 to 80
MPa. The tensile strength in the present invention is measured
according to JIS K 7127 in which a Type 2 test specimen is used and
measurement is made at a test rate of 200 mm/min.
[0053] Further, the drawn sheet preferably has a tensile elasticity
of 1 to 7 GPa. When the drawn sheet has a tensile elasticity of
less than 1 GPa, the sheet will be too stiff, decreasing
moldability of the sheet. When the drawn sheet has a tensile
elasticity exceeding 7 GPa, the sheet will be too soft, which may
cause difficulty in carrying the battery. Particularly preferred is
2 to 6 GPa. The tensile elasticity can be measured according to JIS
K 7127.
[0054] As an index of the sheet transparency, the drawn sheet
preferably has a haze of less than 10%. When the haze is not less
than 10%, the sheet will have decreased transparency, losing the
inherent function of the package. Particularly preferred is 2 to
8%. The haze is measured according to JIS K 7105.
[0055] Further, if a laminate layer made of biodegradable aliphatic
polyester is formed between the base and the container, the base
and the container can be integrated by heat sealing, which will be
described later.
[0056] Instead of forming the laminate layer, if folds are formed
by folding the peripheral edges of the container, the base can be
inserted in the folds whereby the container and the base can be
integrated.
[0057] The holder portion of the container accommodates a battery
pack including a plurality of batteries wrapped in a shrink pack.
It is preferred that the shrink pack is also made of a
biodegradable aliphatic polyester. The biodegradable aliphatic
polyester is preferably a polylactic polymer. The shrink pack is
preferably made of a drawn sheet of the biodegradable aliphatic
polyester.
[0058] The base preferably has a thickness of 50 to 200 .mu.m. When
the base has a thickness of less than 50 .mu.m, the resulting sheet
will be too thin, which may cause difficulty in carrying the
battery. When the base has a thickness exceeding 200 .mu.m, thermal
conductivity will be decreased, causing variations in adhesion
strength when the base and the container are heat-sealed, resulting
in a final package of lower quality. Besides, it is difficult to
control heat during the heat sealing process.
[0059] The laminate layer preferably has a thickness of 20 to 80
.mu.m. When the laminate layer has a thickness less than 20 .mu.m,
the cushioning property of the laminate layer itself will be
decreased, causing variations in adhesion pressure and adhesion
strength during heat sealing. Further, when the thickness is less
than 20 .mu.m, the laminate layer may stretch too much and be
susceptible to rupture. Conversely, when the laminate layer has a
thickness greater than 80 .mu.m, a longer time will be needed in
the heat sealing process, and the base may be adversely affected
(e.g. deformed) by excessive application of heat. Particularly
preferred is a thickness of 40 to 60 .mu.m.
[0060] As mentioned above, when the printing layers are formed only
on the second surface of the base, the laminate layer can be
omitted.
[0061] The drawn sheet preferably has a thickness of 200 to 600
.mu.m. When the sheet for the container has a thickness less than
200 .mu.m, the tolerance range for heat during molding will be
small, and the sheet will be deformed (e.g. stretched too much or
the like) due to its small thickness. Moreover, heat control during
molding will be difficult. Even when the sheet has a thickness
greater than 600 .mu.m, no further improvement can be expected.
[0062] The printing on the base can be done by a conventional
method. The bonding of the laminate layer to the base can also be
done using a conventional adhesive. Examples of the adhesive
include a vinyl adhesive, an acryl adhesive, a polyamide adhesive,
a polyester adhesive, a rubber adhesive and a urethane
adhesive.
[0063] In the present invention, however, it is preferred to use a
biodegradable adhesive made of a polysaccharide such as starch,
amylose or amylopectin; a protein and a polypeptide such as glue,
gelatin, casein, zein or collagen; unvulcanized rubber or aliphatic
polyester.
[0064] (2) Method for Producing Battery Package
[0065] Hereinafter, a description will be given of a method for
producing a battery package according to the present invention.
[0066] The battery package according to the present invention can
be produced by the steps of: forming a drawn sheet of biodegradable
aliphatic polyester into a container having a holder portion by
vacuum forming; and integrating the container with a base made of a
drawn sheet of biodegradable aliphatic polyester to obtain a
battery package.
[0067] The method for producing the battery package according to
the present invention will now be discussed briefly.
[0068] FIG. 3 is a flowchart illustrating the major steps of a
first embodiment of a method for producing a battery package
according to the present invention. FIG. 4 is a flowchart
illustrating the major steps of a second embodiment of a method for
producing a battery package according to the present invention.
[0069] In the first embodiment, as shown in FIG. 3, a drawn
biodegradable resin sheet is formed into a container having a
holder portion by vacuum forming in the container molding step
(1-1). Subsequently, in the base bonding step (1-2), a laminate
layer composed of a drawn biodegradable aliphatic polyester
material is bonded to a base composed of a drawn sheet of
biodegradable aliphatic polyester to give a bonded product. The
container molding step (1-1) and the base bonding step (1-2) may be
performed simultaneously, or separately (e.g. either step may be
performed prior to the other).
[0070] In the integration step (1-3), the laminate layer in the
bonded product and the container are heat-sealed. Thereby, the base
and the container are integrated to obtain a battery package
according to the present invention (blister pack). In FIG. 1, the
step of accommodating a battery pack in the container is
omitted.
[0071] In the second embodiment, as shown in FIG. 4, a drawn sheet
of biodegradable aliphatic polyester is molded into a container
having a holder portion by vacuum/pressure forming in the container
molding step (2-1) in the same manner as the container molding step
(1-1) of the first embodiment. Subsequently, in the fold formation
step (2-2), the peripheral edges of the container are bent on the
opposite side of the holder portion to form folds.
[0072] The shape and size of the folds will be described in detail
in Examples given later. The folds may have any shape and size as
long as the base and the container can be integrated in the
integration step (2-3) and they allow the battery pack to be
retained in the holder portion. For example, the peripheral edges
of the container may be bent on the opposite side of the holder
portion.
[0073] Finally, in the integration step (2-3), the base made of the
drawn sheet of biodegradable aliphatic polyester is inserted into
the folds. Then, by blister process for integrating the container
and the base, a battery package according to the present invention
is obtained. In FIG. 2, the step of accommodating the battery pack
is also omitted.
[0074] FIGS. 3 and 4 show only the major steps of a method for
producing a battery package of the present invention. The detailed
conditions for each step and the additional steps such as the step
of accommodating the battery pack before the integration step will
be described in EXAMPLEs below.
[0075] Hereinafter, the present invention will be described in
further detail with reference to EXAMPLEs, but it is to be
understood that the invention is not limited thereto.
EXAMPLE 1
[0076] In this example, a battery package 1 according to the
present invention having the structure shown in FIG. 1 was produced
in accordance with the steps of the first embodiment shown in FIG.
5.
[0077] (1) Container Molding Step
[0078] Using a resin composition containing polylactic acid
(hereinafter referred to as "PLA") and polybutylene succinate
(softening agent A) in a weight ratio of 100:6 and another resin
composition containing PLA and polycaprolactone (softening agent B)
in a weight ratio of 100:6, transparent drawn sheets having a
thickness of 250 .mu.m were prepared. The drawn sheets had a
tensile strength (breaking strength) of 66 MPa in length direction
and 65 MPa in width direction, a tensile elasticity of 3.2 GPa in
length direction and 3.1 GPa in width direction, and a haze of 10%.
The heat shrinkage of the drawn sheets was measured according to
JIS Z 1712 in which a test specimen was heated at 120.degree. C.
for 5 minutes. As a result, the drawn sheets had a heat shrinkage
of 3.7% in length direction and 1.7% in width direction.
[0079] In a battery package 1, a certain mark was printed on the
surface of a holder portion 3a of a container 3 opposite to the
base 2 by rotary printing using a UV ink. The mark states that the
battery package 1 according to the present invention is made of a
biodegradable resin and thus an environmentally friendly
product.
[0080] Then, using a vacuum forming machine, each of the drawn
sheets was formed into a container 3 having the shape shown in FIG.
1 by vacuum forming at a forming temperature of 110.degree. C.
[0081] (2) Base Bonding Step
[0082] Separately from the container molding step just described
above, a translucent drawn sheet of PLA having a thickness of 100
.mu.m was prepared as a base 2. The base 2 had a tensile strength
(breaking strength) of 110 MPa both in length and width directions,
and a tensile elasticity of 4.0 GPa in length direction and 4.4 GPa
in width direction. The heat shrinkage of the base was measured
according to JIS Z 1712 in which a test specimen was heated at
120.degree. C. for 5 minutes. As a result, the base had a heat
shrinkage of 1.7% in length direction and 0.5% in width direction.
A certain print was given on the surface of the base 2 facing the
container 3 (first surface) by rotary printing using a UV ink.
[0083] Subsequently, as a laminate layer, a transparent drawn sheet
of PLA having a thickness of 50 .mu.m was prepared. The laminate
layer had a tensile strength (breaking strength) of 110 MPa both in
length and width directions, a tensile elasticity of 3.8 GPa in
length direction and 4.3 GPa in width direction, and a haze of 2%.
The heat shrinkage of the laminate layer was measured according to
JIS Z 1712 in which a test specimen was heated at 120.degree. C.
for 5 minutes. As a result, the laminate layer had a heat shrinkage
of 2.7% in length direction and 0.3% in width direction.
[0084] The laminate layer was bonded to the printing surface of the
base 2 (first surface) using a polyamide adhesive to give a bonded
product.
[0085] (3) Integration Step
[0086] A battery pack containing four cylindrical AA batteries
(shrink-packed) 4 was prepared, which was then accommodated in the
holder portion 3a of the container 3.
[0087] Finally, a brim 3b of the container 3 and the laminate layer
(not shown in the drawing) on the base 2 were bonded by heat
sealing at 100.degree. C. Thereby, a battery package 1 of the
present invention was obtained.
EXAMPLE 2
[0088] A battery package 2 according to the present invention was
produced in the same manner as in EXAMPLE 1 except for the
following points. Instead of using the laminate layer, on the other
surface of the base 2 (second surface) were successively formed a 5
.mu.m thick first printing layer made of a UV ink by relief
printing, a 12 .mu.m thick anti-offset layer made of a UV ink by
flexographic printing and a 5 .mu.m thick second printing layer by
relief printing. The base 2 and the container 3 were directly
bonded by heat sealing at a heating temperature of 100.degree.
C.
COMPARATIVE EXAMPLE 1
[0089] A battery package 3 for comparison having the structure
shown in FIG. 1 was produced in the same manner as in EXAMPLE 1
except that the softening agent was not added to PLA used for
production of the drawn sheet of the container 3 and that the
container 3 was obtained by vacuum/pressure forming at a forming
temperature of 100.degree. C.
[0090] [Evaluation]
[0091] The battery packages 1 and 2 and the battery package 3 for
comparison produced above were subjected to the following
evaluation tests.
[0092] (1) Drop Test
[0093] The battery packages 1 and 2 and the battery package 3 for
comparison, ten of each, were packed in a unit packing box by a
conventional method. Each of the boxes was dropped onto a concrete
surface from the height of 50 cm, which was repeated 5 times.
[0094] The number of damaged battery packages after the box was
dropped 5 times is shown in Table 1.
[0095] (2) Vibration Test
[0096] The battery packages 1 and 2 and the battery package 3 for
comparison, ten of each, were packed in a unit packing box by a
conventional method. Subsequently, a packing box containing five
unit packing boxes was formed for the battery packages 1 and 2 and
the battery package 3 for comparison, which was then subjected to
vibration test at a vibration frequency of 5 to 50 Hz for about 10
to 30 minutes.
[0097] As a result, no scratch, crack and deformation were found in
any of the battery packages.
[0098] (3) Storage Test
[0099] The battery packages 1 and 2 and the battery package 3 for
comparison, five of each, were prepared and stored at a controlled
temperature of 40.degree. C. and a high humidity of 90% RH for 168
hours, after which they were visually checked.
[0100] The number of cracked or deformed battery packages is shown
in Table 1.
[0101] (4) Weather Resistance Test
[0102] The battery packages 1 and 2 and the battery package for
comparison, five of each, were prepared and subjected to a solar
radiation test using a sunshine weather-meter at a temperature of
63.degree. C. for 340 hours.
[0103] The number of yellowed battery packages is shown in Table
1.
1 TABLE 1 Material Evaluation results Vacuum Weather Laminate
forming into Formation method Drop Storage resistance Base layer
Container container of container test test test Ex. 1 PLA PLA PLA +
possible Vacuum 6/50 0/5 0/5 softening agent A PLA PLA PLA +
possible Vacuum 8/50 0/5 0/5 softening agent B Ex. 2 PLA -- PLA +
possible Vacuum 4/50 0/5 0/5 softening agent A PLA -- PLA +
possible Vacuum 6/50 0/5 0/5 softening agent B Comp. PLA PLA PLA
not possible Vacuum/pressure 10/50 0/5 0/5 Ex. 1
[0104] The results shown in Table 1 clearly indicates that the
battery packages of EXAMPLEs 1 and 2 are similar to the battery
package of COMPARATIVE EXAMPLE 1 in terms of drop strength, storage
characteristics and weather resistance characteristics. This means
that the battery package according to the present invention is
excellent in strength and productivity.
[0105] The battery package according to the present invention can
accommodate any articles and it is suitable for display at
stores/shops.
[0106] Although the present invention has been described in terms
of the presently preferred embodiments, it is to be understood that
such disclosure is not to be interpreted as limiting. Various
alterations and modifications will no doubt become apparent to
those skilled in the art to which the present invention pertains,
after having read the above disclosure. Accordingly, it is intended
that the appended claims be interpreted as covering all alterations
and modifications as fall within the true spirit and scope of the
invention.
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