Note: Descriptions are shown in the official language in which they were submitted.
u~
1 This application is a division of application serial
number 465,655 ~iled October 17, 1984.
BACKGROUND OF T~E INVEN~ION
The present invention relates to an injection
molding method and to an injection molding metal mold assembly
used in such a method. More particularly, the invention
relates to an insert molding method in which an injection
molding machine is used to inject molding material into an
insert of, for instance, aluminum foil to manufacture a
molding in which the insert is integral with the molding
material, and also to a metal mold assembly used in the
method.
In an insert molding method of this type, insertion
accuracy of the insert and the molding material is
15- essential. For insertion by injection molding, the insert is
inserted into the metal mold assembly in advance. However,
this method suffers from a problem in that the insert can
easily be displaced during molding, and the accuracy of the
resultant molding is hence often lower than required.
Examples of the conventional method in which an
insert is inserted into a metal mold assembly in advance and
molding material is injected to the insert to form an insert
molding are a method in which an insert plate is set along the
configuration of the core mold of the metal mold assembly, a
method of which an insert plate is set in the metal mold by
, l~S~Lt~'8
1 inserting the positioning pin of the metal mold into a
hole in the insert plate, and a method in which a film
plate is held by a holding mold provided for the cavity
mold so that the plate is automaticall~ cut and pushed
into the cavity (see Japanese Laid-Open Patent Application
No. 5747/1981~. However, in these conventional methods,
the positioning accuracy of the insert is low, and the
insert is not satisfactorily held. Thus, it is difficult
to obtain moldings high in insertion accuracy utilizing
these conventional methods.
Furthermore, the conventional methods are
different from an injection molding method in which,
according to the invention, displacement of the insert
during the molding operation is prevented to obtain a
molding high in insert.ion accuracy and which has a
fold as the bottom or cover (top) of a can-like
container.
BRIEF DESCRIPTION OF.THE DRAWINGS
Fig. 1 is a perspective view showing a can-like
container with a rectangular cover to which this
invention relates;
Fig. 2 is a perspective view showing a can-like
container with a round cover to which the invention
relates;
Fig. 3 is a sectional side view of the bottom of
the container;
Fig. 4 is a sectional view of th~ angular covex;
4~7U~
1 Fig. 5 is a sectional view of the round cover;
Fig. 6 is a sectional view for a description of
an insert inserting s~ep;
Fig. 7 is a sectional view for a description of
the start of a mold closing operation;
E'ig. 8 is a sectional view for a description of a
molding material injecting step which is carried out after
the mold closing operation;
Fig. 9 is a sectional view of a metal mold
assembly using a guide member different from the one in
Figs. 6, 7 and 8;
Fig. 10 is a sectional view for a description of
a molding material injecting step which is carried out
after the metal mold assembly (Fig. 9) has been closed;
Fig. 11 is a sectional view used for a descrip-
tion of the insert inserting operation which utili~es
a suction device;
Fig. 12 is a sectional view for a description of
the start of the closing operation of the metal molds in
Fig. 11;
Fig. 13 is a sectional view used for a description
of the molding material injecting operation which is
carried out after the mold closing operation;
Fig. 14 is a plan view for a description of
another embodiment of the invention;
Fig. 15 is a sectional vi~w used for a ~escription
of another embodiment of the invention;
'7U8
1 ~igs. 16, 18, 20, 22, 24 and 26 are top views o~
respective further embodiments of container top of the
invention;
Figs. 17, 19, 21, 23, 25 and 27 are cross-
sectional views of the covers of Figs. 16, 18, 20, 22, 24
and 26, respectively;
Fig. 28 is a perspective view showing a container
body fabricated in accordance with one aspect of the
present invention;
Fig. 29 is an exploded plan view showing the
container body of Fig. 28 in the unfolded state;
Fig. 30 is a perspective view showing a female
mold used in the fabrication of the container body of the
invention;
Fig. 31 shows a male mold used with the female
mold of Fig. 30;
Fig. 32 shows the molds of Figs. 30 and 31
assembled together;
Fig. 33 is a perspective view showing another
example of a container body of the present invention;
Fig. 34 is a perspective view showing a complete
container of the present invention;
Fig. 35 is a cross-sectional view of the container
of Fig. 34;
Fig, 36 illustrates a container of the invention
having a generally rectangular shape; and
z~ u~ f~
1 Figs. 37A to 43 illustrate a method of producing
a container of a generally cylindrical shape~
A can-like container to which the invention re-
lates and its bottom and cover ~top~ will be described.
Fig. 1 is a perspective view showing a can like
container having a side wall 1, a bottom 2 and a
rectangular cover 3. Fig. 2 is also a perspective view
showing a can-like container having a side wall 4, a
bottom 5 and a round cover 6.
Fig. 3 is a sectional view of the bottom 2 which
is to be joined to the side wall 1. In Fig. 3, reference 7
designates a base material such as metal foil or sheet which
air, water, etc. cannot permeate (hereinafter referred to
a "a gas barrier type base material" when applicable).
Examples of the base 7 are aluminum foil, and sheets of
saponified ethylene vinyl acetate copolymer, polyvinylidene
chloride and polyamide. Typically, the aluminum foil is
used. A resin layer (not shown in Fig. 3) which can be
made molten by heating is formed on one or both sides of
the gas barrier type base material.
The molding shown in Fig. 3 is manufactured by
inserting the gas barrier type base material or a base
material having a thermally meltable resin layer into a
me~al mold where molten molding material is injected into
the base material (or at insert) by an injection molding
machine. In Fig. 3, reference numeral 8 designates a
synthetic resin layer which is formed by in~ection. The
12~ 7~
1 molding in Fig. 3 must have a fold 9 to join it to the
side wall 1.
Fig. 4 is a longitudinal sectional view of the
rectangular cover 3 (Fig. 1) which is to be joined to the
side wall 1. In Fig. 4, reference numeral 10 d~signates a
base material. In the case of Fig. 4, the base material 10
is obtained by forming thermally meltable resin layers 12
and 13 and both sides of a metal foil 11. In Fig. 4,
reference numeral 14 designates a synthetic resin layer.
The molding in Fig. 4 can be obtained by injection
synthetic resin molding material into the base material
(insert~ 10, similar to the case of the bottom shown in
Fig. 3. In Fig. 4, reference numeral lS designates a
handle ~a so-called "pull top") on the cover. When the
handle 15 is lifted with a finger tip inserted into a
groove 16, the base material 10 is torn below the
position 17 so that the cover 3 is pulled off. Further
in Fig. 4, reference numeral 18 designates a treatment
layer to facilitate the peeling of the handle portion
2Q from the base ma erial 10. The moldin~ in Fig. 4 has a
fold 19 similar to the case of the molding in Fig. 3.
Fig. 5 is a longitudinal sectional view of the
round cover 6 shown in Fig. 2. The round cover 6 is
manufactured in the same manner as the molding in Fig. 4.
~5 In Fig. 5, components similar to those in Fig. 4 are
designated by the same reference numerals and their
S~';;'~'8
1 descriptions are omitted. The molding in Fig. 5 also has
a fold 19.
In the injection molding of a flat part which,
unlike the moldings in Figs. 3, ~ and 5, has no fold
(~ or 19), for instance, in the case of injecting molding
material into a round insert, a slight displacement thereof
causes no trouble. On the other hand, ifl in the case of a
molding with a fold (which the invention concerns), the
insert is displaced even slightly during molding, undesirable
results occur. It is impossible to obtain a molding high
in insertion accuracy.
Further in a conventional method of adhering a
multi-layer sheet to its outer synthetic resin layer to
improve the gas barrier characteristics, after the outer
synthetic resin layer is formed by injection molding or the
like, an adhesive is used to cause the multi-layer sheet
to adhere thereto.
This conventio~ method suffers from the following
problems: (1) the number of manufacturing steps is high and
the manufacturing cost high, (2) the adhesive must be
hygenic, and (3) the synthetic resin layer may peel off
the multi-layer sheet if repeatedly heated and cooled.
It is desirable to make the outer resin layer
integral with the multi-layer sheet, ~or ins~ance, by
insert injection molding which prevents the permeation
o~ moisture and oxygen and the transmission of light
to improve the gas barrier characteristics, thereby to
7VEi
-- 8 --
1 provide a can-like container's cover in which the outer
resin layer is strongly joined with the multi-layer sheet.
However, when the outer resin layer is joined with the
multi-layer sheet, the handle ~or "pull top") o~ the cover
is also joined with the multi-layer sheet, with the result
that it is impossible to peel the handle off the multi-
layer sheet or the body of the cover.
Further, in order to improve the openability of
the opening part, a slot or groove is, in general, formed
in the cover so that the opening part is opened along the
slot. However, the formation of the slot unavoidably lowers
the moldability. In order to overcome this difficulty,
in the formation of the resin sheet according to the
aforementioned method in which the resin sheet is bonded
to the aluminum foil, the slot is divided into a plurality
of parts, i.e., instead of one slot, a plurality of slots
connected through bridges are formed to permit the smooth
flowing o~ the molding material to maintain the moldability
~see Japanese Laid-Open Patent ~pplication No. 39489/1977~.
The method is advantageous in that the moldability
is improved; however, it is obvious that the openability
is lowered by the bridges.
The present invention ~urther relates to a con-
tainer made of a multi-layer sheet in which plural
plastic coating layers are formed on an alu~inum base
foil layer. Particularly, the invention relates to such
a container which can be used for storing food ~or long
7(~8
g
1 periods of time and in which the food stored in the
container is kept out of ccntact with the metal of the
base layer.
Metal cans suffer from various problems, in-
cluding an adverse effect on the taste of the foodcontained therein and numerous difficulties in fabricating
such cans. With the view of providing a container which
is free of such defects, it has been proposed to fabricate
a container from a multi-layer sheet composed of an aluminum
foil base and multiple plastic layers formed on both sides
of the base layer.
To form a three-dimensional container from such a
flat multi-layer sheet, a method has been known whereby the
peripheral edges of the multi-layer sheet are clamped in a jig
and a downward pressure is applied to the sheet. This
operation is generally effected with a cold press roll.
According to this process, however, since the multi-layer
sheet is unavoidably stretched, the aluminum foil base layer
has an uneven thickness, and pin holes or cracks are likely
to occur therein. Accordingly, it is necessary to employ
a relatively thick foil of 60 to 100 ~m, and accordingly,
the production costs of the container are high. Moreover,
because the process includes stretching of the aluminum
fo.il, it is difficult to fabricate a deep container.
In another approach for producing a three-
dimensional container such as a rectangular container
from a flat multi-layer sheet, the sheet is first notched
S~7(}~
-- 10 --
1 (cut away~ in suitable portions, and then the flaps thus
formed are folded inwardly. According to this process,
however, the cut sections contact the contents of the
container, making the container not suitable for food
storage.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention
is to provide a can-like container which is free from the
above-mentioned drawbacks.
More specifically, it is an object of the present
invention to provide such a can-like container employing a
multi-layer sheet as a starting material which has a thin
al~minum foil base.
Yet more specifically, it is an object of the
present invention to provide such a container in which
the multi-layer sheet is formed into the container without
the aluminum foil base layer thereo cracking or incurring
pinhole defects.
Still further, it is an object of the present
invention to provide such a container in which there is no
effect on the taste of the food contained therein.
Still another object o the present invention is
to provide such a can-like container having a container body
formed of a multi-layer sheet which is joined to a cover
usin~ a hot-melt resin process, thereby providing an
excellent barrier against the infusion of gas and hence to
provide for a long storage period of food held in the con-
tainer.
s~
1 A still further object of the present invention
is to provide such a can-like container which uses a
metal foil for its base which is sufficiently thin that
the container can ~e easily incinerated, thereby to make
disposal of the can easier than for prior art cans.
A yet further object of the present invention is
to provide such a container which is prevented from
being deformed or crushed during transportation or
stacking so that the sealing property of the container
is significantly improved.
In accordance with the above and other objects of
the invention,the present invention provides a can-like
container fabricated from a multi-layer sheet composed
of a thin metal foil base and a resin layer and having a
uniform thickness. More specifically, the body of the
container is made of a multi-layer sheet composed of a metal
foil base layer having a thickness of 40 ~m or less and
a hot-melt resin layer on one or both sides of the metal
foil base layer, and a cover composed of at least two
~0 layers including a metal foil layer and a hot-melt resin
layer formed on at least of one side of its base layer.
The container body is molded in such a way that the corner
portions are Eormed by making three-layer folds therein or
by gathering the sheet material in the corner portions into
vertical wrinkles.
~ZS~7U~3
-- 12 --
DE~CRIpTION OF THE PREFERRED EMBO~IMENTS
A molding method of the invention will be
described with reference to t~e case where a stripper
plate is used as a guide member as shown in the drawings.
A stripper plate is generally used to eject and
remove a molding from the metal mold in the injection
molding machine. The applicant has developed a novel
injection molding method in which an insert is inserted
and fixedly held in the stopper plate to lmprove the
insertion accuracy and to prevent the displacement of
the insert. Accordingly, the method of the invention is
suitable for providing an insert molding having a fold
supported by the insert.
The invention will now be described in more
detail with reference to the accompanying drawings.
Fig. 6 illustrates a method of inserting an
insert into a metal mold. In this embodiment, a robot
(not shown) is used to insert the insert into the metal
mold. An insert 21 is sucked and retained by a suction
plate 2G which is connected to the arm of the robot.
Under this condition, the movable cylinder 22
S9~7~
of the ~obo~ is moved downwardly in ~he direction of
the arrow 2~ and then ~ov2d ~ideways in ~he direction
of the arrow 2~ ~o tha~ the in~ert 21 is in~erted irlto
a ~tripper plate ~6 pro~ided for A metal mold ~core
type). E~en if, in this operatio~ robot moves
the insert 21 obli-qu~ly ~i*~ xespec~ h2 i~er
surfacP of ~he metal mold, the insert 21 will still be
~uitably inserted lr.to ~he Jnetla mold because ~t i~
guide~ by ~he inner ~all 27 ~ the stripper plate ~
~at is, tha insert 21 i~ ~moothly guided~by the
~trip~er plate ~6 ~ ~11 ~imes.
~he insert i~ generally larger t~ he hol~ ~ut
in t~e -~tripper p~lte 26J ~rherefore, ~the ~ser~ 21 i~
retai~d anà po3itioned by t~e stripper plat~ 26 when
i~serted, that i8, il; iS fixedly h~ld in ~he stripper
plate ~6 when in~ert~d. In Fig~. 6 and 7 th~ough 11,
the insert i~ shown oriented in a vertical direction
by the stripper pla~e ~nd fixedly held ~hereirl. ~ow-
~ver, i~ ~hould be tloted tha~ tha insert i~ retailled
or~ four side~.
~fter tha in~rt has ~een fixedly held in the
stripper plate, ~he mova~le cylind~r 2~ of ~he robot
i~ moved in ~he dirPction o~ the arrow ~8 arld then
lifted in the direc~ioT~ of tha arrow 2~.
Fig. 7 ~how~ the insert fixedly held in th~
~tripper plate ~6 with ~he robot ' ~ cylinder having
been lifted ~way, Under 'I hi8 condition, ~he metal
mold ( core-type, mcvable ) ~5 is moved laterally to
-- 12i~17
14
start a mold clo~ing step wi~h a metal mold (cavity-
type, 6tationary) ~2 haYing an injec~ion nose 30 and a
mQlding material supplying path 31 ~o3mn~cated with
~e gate 3~ at the center. In thç closing step, :the
5insert 21 cann~t be displac~d because it is fix~dly
held by the stripper 26.
- As ~ho~ in Fig. ~, at the er~d o~ the alosing
step, the peripheral por~io~ of the inser~ 21 is
fo~ned into a fold ~3, ~nd ~olten moldi~g Tnateri~
10is injected through the i~iection port 30 ' into a
ca~rity 34 which i~ forr~ed by tl~e coxe-t~rpe metal
mold 2S a~d . the cavity-t~pe metal mold 30. ~Che
molding has a fold ~nilar ~ th~ moldlng~ ~hown in
Figs. 3 thxou~ 5. Ill the a~o~e-described operatioal,
15the i~sert is no~ displaced at all. Therefore, the
~olding has a high insertion accuracy, ~nd the moldi~g
material is applied to the fold also with a high
accuracy.
After molding ma~erial iniec~ion, pressuri~ing,
~cooling, mold opening, mold ejecting and mold re~ov-
ing, ~teps may b~ carried out according tc ~he
.~ordinary injection molding cycle to obtain the
m~ldin~. However, ~ccording to the invention, the
. insert is inserted a~d fixedly held by means of ~h~
25stripper pla~e, ~nd ~he molding is ejected and remoYed
wi~h the aid of the stripper plate, 60 that ~he
injeçtion moldin~ is ~chi~Yed mor~ ~fi ~i ~nt.l y .
S~ B
1 In the above~described embodiment, the insert i~
in~erted into the 3tripper platP and fixedly held
therein. ~owe~er, ~he guide mem~e~ in the inYention
may be any one which ha~ the ~o~e-described function~
and can achieve the object~ of the invention.
Fig. 9 illustrates another embodlmen~ of t~he
invention.~ I~ thi~ embodiment, a guid~ member 36 i8
connected through springs 35 to the upper and lower
portion~ of a stationa~y metal mold 3~. An insert 21
is in~rted into the ~uide me~'oçr 36 and fixedly held
~herein. Vnder thi~ condition, a mold clo~ m g opera-
tion i~ carried out a~ ~hown in Fig. 10, and then an
injection moldi~g operation is perfor~ed ~ de~cri~ed
with reference to ~igs. 6 r 7 and 8. In ~ig. 10, th~
15 lnsert 21 ~Fig. 9) i8 not ~hown.
Fig. ll depicts a ~hird embodi~ent of the i~ven~
~ion. In this embodiment, th~ in~ert in~erted in the
guide member is more positively ~ixed ~her~in by mea~s
of ~uctio~ d~vice ~uch as a vacuum cylinder provided
i~ the me~al mold. This mathod is adv~ntageously
applicabl& ~ a ca~ wh~.r~ mnld;ng ~hn~ h~ ~rrt R~
out ~ higher speed or a ca~ where a l~rge number o~
moldings 6hould be manu~ac~ured. In ~hes~ cases, ~he
method can more po~i~ively pre~ent the displacem~nt
of ~he insert and thus ~oxe ~ompletely ~o~tribute
to improving the in~ertion accuracy. Furthe~moxe,
according ~o thi5 method, the injec~ion moldlng is
carried out wi~h the insert sucked and retained by ~he
47~B
vacuum cylinder, and ~herefore deformation o~ the
in~ert i~ ~ositively pxeven~ed.
The third embodiment will be Llescribed furtller
wi~ refere~ce to ~ig~;. 11, 12 ~d 13. A~ ~howrl i~
Fi~. 11, a~ insert 21 i~ ~ucked a~d rel:ained by ~he
31~C*i~O~1 ~la:~ t~r ~ac~ion ~i~c~ ::2Q ~ obot. IJnder
thi~ condition, the movable cylinder 22 oî 1:he robot
i~ moved dowrlwardly in the directioll of the arrow 23
and i~ then ~oved in the ~re~ion of the arrow ~4.
A~ a result, the insert 21 is in~erted into a guide
memb~r ~6 ~rouided ~or a ~e~:al mold 25 while l~eing
~uided by the guide member 26, ~nd is ~ dly held
(po~ ed~ ~herein~ ~hu6, ~e.~pl~c~ment Df the
in~ert i~ preven~ed. In ~hi~ operation, the i~s~xt 21
S i~ mor2 firmly held therein ~ecause it iB held by a
~acuum cylind~r 37 provided in the metal mold ~5.
~he vacuum cylin~er 37 ha~ a through-hole 33 which i~
connected ~hrough ~ pipe 39 to a vacuum pump ~not
shown~ 60 that the in~ert ~1 i5 ~hereby attrac~d
towards ~he metal mold 25. The robot' 8 movable
cylinder ~2 is moved in the direction o~ the arrow 28
and i9 then lift~d in the direc~ion of ~he arrow 29
before the mold closing operation is carried ou~.
Fig. 12 ~hows ~he start of ~he mold closi~g
operation, and Fig. 13 the en~ o~ the mold closing
operation, In ~he mold clo6i~g operatiQn, the vacuum
cylind~r 37 is slide i~ a cylinder Aou~ing 41 in the
dir~ction of the arrow 40 as ~hown in Fig. 1~; that
S4'~
17
is, the ~a~uum ~ylinder 37 move~ in~o the metal
~old 25 as ~hown i~ E'ig. 1~. In ~ig~. 12 ~nd I3,
hro~gh-hole 3a is ~ot ~;ho~m~
Upon completion of the mold closing operation,
S mold~ny material i~ injec~ed through the molding
ma~erial ~pplyi~g path 31 and the injectioll gate 30
of ~he metal r~old 32 into t~e cavity 34 which i~
~ormed by ~he ~ei:al ~olds. ~he o~her ~tep~ ~re ~he
same a~ ~hose irl the above-described embodimen~.
In the above-descri~ed embodimen~s, th~ inser~ is
larger than the hold of the guide member. However, in
~a~ ~here ~he illser~ ~ ~maller than ~he hold ~
the guide member, the insert ~an be fixedly held by
employing at least one ~ib e~tending ~r~m ~:he l~ner
periphery of the guide mem~er.
~ig. 14 is a fro~t view of a ~tripper p~ate 26
with ribs 42. The angle (draft3 o the inner wall 27
of the guide member ~6, whi~::h i~ b~ought into co~tact
with the inser~ 21, may be ~ui'cably controlled. ~his
will be de~cril~ed with reference to ~ig. 15 ~hi~
an enlarged 6ide view of the guide member 26. In
~ig. 15, the an~le (x~y) is adju~ted so tha~ a large
insert can be smoothly inserted into the guide membe~
and ~i~sedly held t~erein.
In order to clarify the e~fect~ of the invention,
examples thereof will be desc~ib~d.
18
T21e bottom of a ca~ like c~ntaiRer ~as ~o~ded by
using an injection moldir~g machine IS-50~(30Z) manu-
fac~ur~d by Ts~hiba Co. of JapaI10
The insert was ~abri~ated ~y forming re in lay-
ers of ethylene proplene black c~polymer ~IFR 1 1 g/
10 min, ethylene conte~t gwt%) on ~oth ~ida~ o an
alumi~n layer. The thickne~se~ of the (outer) resin
layer, the alumixlum layer and hl:e (inner) resl~ layer
~ere 30 microns, 15 microns ~nd 70 microns ,~ respec-
tively. The in~er~ was in6erted l~to $he ~ripp~r
plate of tbe inj e~tion m~ldiag machine a~d f~èdly
held therein by me~ of ~he lobo~. Af~er :~e . ~ol.d
clo ing operation, propylene ethyl~nP bloc3c ~opolymer
o~ MFR 10 . O g~10 min was inj ected into ~e mold
cavity. The ~nolding con~itio~ ~er~ ~ follow~:
Cylinder temperature -- 2~0C
Injection pres~ure:
Pximary pre~sure -~ 60 kg/cm~
Secondary pres3ure -- 40 kg~cm2
~ni ec~ion time -~ 3 ~econds
Coolin~ time -- a ~econd~
Molding cycle ~total ) - 15 seconds
Injected resin thic3cr~e~ 0 . 7 m~
The in~er~ion accuracy of the ba~e material ( insart)
and thP i~jected r~sir~ layer of ~e c~-liXe container
wa~ 0 . 3 to 0 . 5 mm in the longitudinal direction and
0.3 to 0.5 rMI in th~ la~e~al direc~ion.
-~ ~2~/~7
lg
Exam
T~e rect~gular cover showrl in Figs. 1 and 4 was
made in the F,a:me mar:rLer a~ in Example 1 ~ h the
exception tha~ stead of the pr~plyeIle ethylene
bloc3c copoly~er of MER 1~ . O g~10 min, a material
prepared by addmg calcium ~a~ida 40% to that rasin
material ~a6 used.
The in~e~tion ~c~uracy of the retangular cov~r
thu~ cons~ ed wa~ ~iimilar to that of Example 1.
Exa~ 3
~he round cover showIl in ~igs. 2 and 5 wa6 molded
nthe same manne~ a~ that.of Exampl~ 1.
The insertio~ accuracy of the round ~!o~er ~hu~
molded wa~ similar to that o~ e~sample 1.
As i~ apparent froln the abo~re de~cription, even
if the in~ert i~ obliquely moved into the metal mold
by the robo~, it is accura~ely se~ in place beeau~
it is guided by the guide member su~h as a strippe~
plate, and it i6 fixedly held in the metal mold by ths
guide member arld, when desirad, with the aid of ~he
Yacullm cylinder. Therefore, the di~placement of th~
in~er~ during the molding opera~ion is prevent~d.
~ccordingly, ~he insert molding produced has a high
insertion a ;:curacy and low manufacturi3lg cost . Fur~
thennor~, as the molding operation can be achiev~d at
high ~peed, ~he me~hod of tha invention a~tain~ high
producti~i ty .
-- lZS4'~
Moreover, in the abo~re-de~cribed embodiments ~ the
in~er~ i8 ~erted into :the metla mold ~y the robot;
however. t~e in~e~tion may be achiev~d by other
mean~, for iIlstance, guide rail~.
Furth~rmore ~ in the above des~r~bed embodiments,
two-pl~te ~netal ~nold ~assembly is u~ed; however, the
tech~iral coT~cept of ~he invention i~ applicable to a
t~ree-plate ~etal ~old ~ssembly, and other metal mold
as~embli~s. In addit:io~, the cole mold and t~e cavity
~old may be revexsed.
Fig~ 16 is a~ enlarg~d plarl vie~ o~ the re~
lar ~over in ~ig. 1. Fig. 17 i5 an enlarged 6ectional
vi~w takerl along ~ine x-x~ ig. 16. In Fi~. 16
and 17, re~erence numerals 47, 48 a~d 49 designate
secorld resi~ layers. T~e second resin lay~r 48 is
di6tin~uished from th~ Recond resin layers 47 and 49
by a groove 40 . In Fig. 16, reference num~ral ~0 '
de~i~nates a bridge . A handle ( or pull-top ~ 15 is
fo~ed in the ~ec~nd resin layer 4B. In Fig~. 16
and 17, referellce numeral 4~2 designate~ an inner
~roove ~o facilitate the lif~ing of the handle 15.
No second resin layer i~ or}ned in the inner groove 42
and in ~che groot~e 40 , i . e O, a multi~layer sheet 43 i8
expo~ed ~hereir~. The~e groovea are ~ormed by a metal
mold ~o tha~ the cover can be readily opened. In th~
embodiment sho~n in Fig. 17, the mulki~la~fer ~heet 43
i8 manufactured by ~onning resin layers on both ~ides
of a gas ~rrier type base ma~eri~l.
`
~` ~LZ54~!8
21
In Fig. 17, reference numeral 44 designakes a
treatmerlt layer to ~acilitate ~he peeli~ ~f ~
handle. The treatment layer 44 may be formed over all
the area of the ha~dle or ~a part ~f ~he ~rea;.however,
it iæ preferable ~ak it be. fonned on t~e en ir~ rear
~face o~ the handle .
~hen the har~d~e 15 i~ ted, ~he handle lS i8
readily peeled off ~he multi-layer sheet ~3 whil~
go1ng inside at ~he pasition 45 to cut the multi-layer
~heet 43 BO ~hat the cover is r~adily o~e~ed along
the groove 40. In Fi~. 4, reference ~ l 46 ~es-
ignates tw~ opposed parts o~ ~he slde wall.
~ig. l~l is ~ ~nlarge~ ~ew ~Df ~he ~;m~
cover show~ in Fig. 2. ~ig. 19 i~ ~n enlar~ed sec-
tional view ~aken along line ~-~' in Fig. lB. In
Figs. la and 19, those parts having the ~ame unctions
as those in Figs. 16 and 17 are therefore designated
by the ~ame re:Eerence num~ral3. A~ the rectangular
cover shown in Fig~ and 17, ~he handle 1~ can be
readily op~n~d.
I~ order to clarify ~he ~f~ects o these embodi-
ments o inv~ntion, speciic example thereof will be
d~cxibed .
~xam~le 4
A multi~layer sheet havin~ a ~ructur~ and a
thickne~s as indica~ed in T~ble 1, which was coated
wi~h rubber ~eries gra~ure printing inX, wa~ insex~ed
in~o a ~tripper pla~ provided for a m~tal mold and
S4'~
- 22 -
1 fixedly held therein by means of a robot. Under this
condition, the rectangular cover shown in Fig. 16 was molded
by injection molding. An injection molding machine
lS-50A~30Z~ made by Toshiba Co. was used. The injection
molding resin material used was ethylene propylene block
copolymer ("SHO-ALLOMER*" MK 411C (made by Showa Denko Co.)
MFR 10.0 g/10 min.~. The molding conditions were as
follows:
Cylinder temperature -- 280C
NH Hl H2 H3
260 280 260 240C
Injection Pressure:
Primary pressure -- 110 kg/cm
Secondary pressure -- 70 kg/cm2
Mold closing pressure -- 120 kg/cm2
Comparison Example 1
A rectangular cover was manufactured in the same
manner as that of Example 4 with the exception that a
multi-layer sheet not coated with the printing ink was
used.
Examp_e 5
The rectangular cover shown in Fig. 16 was manu-
factured by compression forming. That is, an oil pressure
50-ton press made by Amino Press Co. of Japan was used~
An insert prepared by applying rubber series gravure print-
ing ink to aluminum foil having ethylene propylene
block copolymer (MFR. 1.1, ethylene content
9 wt%) layers on both sides was inserted into
*Trade Mark
iL;~S~U8
23
the mold in advancP. Under thi~ condition, the
compres~ion forrning ~as ~arried out by ~upp~ying a
heated resin ~heet of ethylen2 propylene block ~opoly-
mer l ~Shoaroma" ), MFR 0. 7 g~10 ~in) .
Com~ari~on Exam~le 2
A rectangular co~r~r was made by com~ression
~ning in the same manner as that in Examp~ e
the exception that a multi-layer ~heet not ~oated ~ith
~he printing ink wa~ u~ed.
~
Container co~1rer~ ~,rere manufactured by injection
moldill~ or compression fonning wi~ ulti-layer sheets
and printing ink treatment (~reat~nent layers) a0 shown
in Table 1.
container cover~ were formed ~7it~ multi-layer
sheet as shown in Tabl~ 1. These Comparison Exam-
ple~ 3 through 7 corr~spond ~o Examples 6 through 10
in which no peeling treatment was e~ployed.
lZS~7(~
24
l Table 1
Peeling
Treatmont
Exa~ple (Trcatment For~ing Peel-
~o. ~ Layer ~et~od ability
_ _
4 Outer resin layer (l)/
(30 1~) In j ec~
minum f~il/i~ner resln layer Rubber tion SatiR~
(lS ~) ~7~ ~) series Moldi~g factory
Resln (1)/
inum foil/~esi~ tl~
(l~,u) . " Pres~ "
6 Resin (2)~aponi~ied et~ylene
acetate Yinyl copolyme~
~20 ~) IAjection
resill (2) " ~olding
7 Resin (3)/PV~c/resin (3j
(20 ~) " t~
8 ~e~i~ tl~polyamite/re~in
(~ ~) " " "
Rasin (1)/PAN/re~i~
(20 ~
_ /alu~i~um ~oil/re~in(1) " " "
11 _ Jslumi~um oil~re~in(1) " Pre~
Poly~ ec-
12 Resin tl)/~luminum foil/resint1) smide tio~
(30 ,u) (9 ,u) (70 ~ series ~oldi~g
~itro-
13 ~esin (2)/alumi~um ~oil/re~in(2) cellulose
~9 ,U) serieA
P~per
14 Re~in (3)/aluminum foil~r~sin(3) se~l
(9 1~ Pres~
Injeeo
Resin (1~/aluminum foil/rosin(1) "C~llo- tion
(9 ,u) tape" ~oldlng
l.Z54'7
1 co~par- Peeli~g
i~on T~e~tment
Example ~Txeatment For~ing ~eel-
~o ~ Iay~ Methot sbili~y
I~Jec- No~
1 ~e8in (l)/alum- um 0il/re6L~ tl) Not tion peeled
~30 ~) tl5 ~ f7D y) ~pplied ~old1~g of
I~Jec
3 ~e~in (2)~sapo~ified ethylene tioR
acetat~ vinyl ~opoly~e~/resi~ (2) " moldi~g
4 Re~ 3)/PVDC/r~si~ (3)
~e~in (1 )/polyamide/rexi~ ~1) " "
6 Re3in (l~/PAN/re~in (l~ " " "
7 - /aluminum ~oil/resin ~l)
t~
.
15Note: Resi~ tl) Et~ylene propylene block copoly~er
~ER - ~.1 Ethylene content 9 wt%
~e~in (2) LDPE (high pre~sure method low density
polye~h~lene)
MI = 5.0 De~ity 0~920
Resin ~3) HDP~ (high den~ity polyethylene
MI = 1.0 ~e4sity O.9S0
l;~S4t~ ~B
26
A~ i3 a~parent from the results of the a~ove-
described Example~ and Compari~o~ Exam~les, ~e
printin~ treat~nent or the equival~nt trea~ent ~pplied
to the multi-layer sheet l~cili~es ~e 4pening of
the co~er with t~e handle.
~he .con~ainer cover ~f ~he inven~ion ~a~ ~e
manufactured at ~elatively low C08t, and ha~ the
foll~wing excellent characteri~tics:
(1) A~ printi~g trea~nent is ~ppli~d i:o ~;he
multi -1 ayer sheet which i s in contac~ ~ith the
container cover handle or to the part of the nlulti-
layer shee~ wllere the lat~er is in co~t~ct wi~ i:he
handle, o;r th~ tre~tment lay~r ~uch as a papel ~eal i~
pro~ided in order to allow the handl~ tc peel off the
multi-layer ~heet, the handle can be readily peeled
off the multi~layer sheet, and accordingly th~ cover
can be readily opened.
(2 ~ The ~econd layer i8 formed on the mul~i-
layer sheet by i~s~r~ion forming in ~uch a h~anner
tha~ the former is welded to the latter ~y heat.
Ther~fore, th~ ~eco2ad layer ha~ a hi~ adh~sion
stre~gth and cannot be peeled off by heat cycling,
for irls~ance, in a retort treatment.
(3 ) The second ~eRin layer and the thermally
we}dable reBin layer ~or the multi-layer ~hest
obtained by laminating ~he ~ixst rosin `layers ) are
laminated. Therefore, the cover can be reaily
welded by heating and h~ a retort characteris~iC.
7~8
27
1 Accordi~gly, containers excallent fxom a food hygiene
point of view can b~ made with the covers according to
~h~ invention.
Further e.~bodiments of the invention will now be
described. In Fig~. 20 and 21, ref~rence numeral 3
as before d~siynates the co~er; ~8, an opem ng par~
formed by the second resin layer; 59, a peripheral
part ormed ~y ~he second resin layer; and 60, a ~lot.
The slot 60 is in ~he form of a closed rin~ as ~how~
i~ Fig. 20, and therefore the ope~ing part 58 is
completely ~eparated ~rom the peripheral part 59 by
the ~lo~ 60. Further, in Fig~. 20 and 21, reference
numeral 11 desisnates a handle proYided on the open-
ing part 58; and 62, a cutting opening part S2 by a
groo~e 6~.
In Fig. 21, re~erence ~umeral ~4 designate~ a
multi-l~yer ~heet. }n the ~ase of Fig. 21, ~he
mult--layer sheet is manufactured by forming first
resin layers 66 and 67 on bot'.l 6ides of a gas ~7arrier
type ba~e material. The can-like container'~ cover 3
according to the inven~i~n is ixedly mounted on the
side wall 1 of the can-like c~nt~iner as ~hown in
~ig. 21.
The rectangular cover 3 i~ opened a~ ~ollow~:
When the handle lS is raised with the fingertip
inserted into groove 63, ~he handle 15 is peeled off
the multi-layer ~hee~ 6~. A5 ~ result, the end 69 of
the handle 1 goe3 inside the multi-layer ~hee~ 64 to
l~S4'~
28
cut :t:he latter. When, u~sder this condition, the
handle 15 is pulled, the multi-laye- ~heet 64 i~ cut
along the ~lot 60 ~o that ~e opel~ing part 5~ of the
cover i~ opened.
}n the con~ainer ' 5 c~er according to the inven-
~ion, tlle opening part 58 is completely sepaxated from
*he :peripheral p~ 9 by the siot 60; i.e., no bridge
i~ provided betwee~ the parts 68 and 69. Therefore,
the opening p~ 5a can be readily opened. This
readily opena~le c~n~ainer ' s cover can be prodtlced
u~ing an inj ectioll molding method o~ the inverltion.
~he method will be descrihed wi'ch re~erence to
~ig~. 20 ~d 21. The opening part 58 a~d the pPriph-
eral part 59 are molded using respective gates. That
is~ the opening part 58 iB independently molded using
its gate, whil~ the peripheral part 59 is also
indepe~dent~ y molded by using its own gate, The
slot 60 i~ fon~ed by the mold. At least one ~ate
~hould be provided for molding the op~ning part 58,
and similarly at least one gate should be pro~ided for
molding the peripheral part 59. ~he position~ of the
gates are indica~ed by refer~nce ~haracters 70(~1 )
and 71 (G2 ) in Fig. 20 . Tha~ iB, the opening part 58
is molded usiT~g the gate 70(~1 ), whil~ the periphexal
p~rt 59 is molded 2~ing ~he gat~ 71~G2).
In the injectiorl mol ding method using a plural~
ity of gates, the moldability i~ e~ccellent an.d the
injection nnolding operation carl be achieved readily.
~;~S~Q~
T~Lerefore, rnaterials having a low moldability such a~
ma~erials having ~mall ~el~g fact;ors ~FR ) ~s~s
with fil~ers can be used in the inj ection molding
method. As wa~ de~cribed before, in the conventional
S method, it is nec~ssary to take th~ moldability into
~:o~iderati~ e., it i~ ~ecessary ~o select ~ater-
ial~ having a high fluidity, and it is difficult to
u~e :re~i~s ~7ith filterq. Eowever, these problems have
bee~ sol~ed by ~he pravi~ion of the injer~ion molding
lo method accordir3g to t~he inve~tion.
Furthe~more, in the molding method of the inven-
tio~ the mQId;ns~ temp~rature ~nd tha inieGtion
pres~ur~ are ~ erably low, and 1:he productivity
~molding cycle ) is high. In addition, in the inven-
tion, the slot i~ formed by the pushing action of the
metal mold, and there~ore it is preferable that the
moI d closing pressure is ~uitable for incre~ing the
durability o~ the met~1 mold, preYenting dam~ge ~o the
bas~ ma~erial and preventin~ ~reak~ge of the slot.
According to ~he invention, the mold closing pressure
can ~e low. ~epending on moldillg conditi~ns, some-
times a produc~' 8 corner material ~uch as a~l aluminum
foil may be broken in the mold during inj ection
molding. ~owever, ~uch a problem can bP elimina~ed
by the low inj ection pres~ure employe~ with the
inventiQn.
~ccording to th~ inj ection molding method of the
invention, can~ ce ~ontainer ' s cover~; having a high
7Q~3
3a
adhesion ~trength can be obtained as described above.
Especially wherl a multi-layer sheet having thermally
meltable first resin layers on its bo~h side~ i~ used,
the first and second ~esin layers ~re in a molten
state when molded, aIld are then welded -toget~er.
~herefore, ~e resultant moldins~ i~ high in adhesion
~t~erlgth and accordingly durable in the drop tes~
On the other ha~d, the cover may suffer from the
problem that the ha~dle is ~lso wel~ed ~:o ~:he ~l~i-
layer fiheet so ~a~ it ~annot }; e peeled off the
mul~i-layer sheet. ~owever, thi6 problellL ~an be
sol~ed by applylng a treatment for ~liowing t:he ha~dle
to peel o~ the ~ulti-l~yer ~eet to th~ ~art ~ -th~
multi-layer sheet with which t~e handle is in corstact.
An e~cample o~ ~he trea~nent is to u~e pri~ti~g ink ~o
form a treatment layer a~ described a~ove.
Fig. 22 is an enlarged plan view of th~ round
cover of Fig~ 2, and Fig. 3 is an enlarged ~ectional
view taken along line Y-Y' in Fig. 22.
In Figs. ~2 and 23), parts designated by the ~ame
reference n~nerals as tho9e in ~igs. 20 and 21 have
the ~ame functions, ~nd ~heir descriptlon will be
omitted. The round cover is maIlufac~ured in the same
manner as the rectallgular cover in ~ig~. 20 a~ld 21,
and can be readily opened~ In Fig. 22, 73(~3) desig-
nate~ the position of a gate for the opening par~ 58,
and 74(G4 ) th~ P~it~ q~l;ç ;fQ~ ~ç ~rl~he~l
part 59. The opening par~ and the periphe~ral part
lZS~7~
1~ are formed independently by using the respective
gate~ G3 and G4.
In ord~r to clarify the effects of' t~e above
embodimen~s of the in~ention, ~xamples and Comparison
~xamp:Le~ ~ill now ~e desc~ibed.
~xampls 16
An injection Jnolding tna~i~e IS-50A~30Z) made by
To~hi~a Co. wa~ u6ed to f~ he rectarlgular cover
- ~hown i~ ~ig. 20.
~ Used for tbe formation of the cover wa6 a multi-
layer sheet wh~ch was fabricated by forming ethylene
propylene block copolymer (MER 1.1, sthylene content
9 wtæ) laye~s o~ ~oth sides of ~n aluminum foil~ The
inj ec~ion molding operation wa5 carried out with the
multi-layer ~heet fixedly held in the metal mold by
the rohot. The two gates ~1 and G2 shown in Fig. ~0
were used for molding. The slot was formed by ~e
pushin~ a~tion of` ~he metal mold. ~he second resin
layer, fornled ~ith the product 'rShoaroma" manufactured
by Showa Denko Co. ~propylen~ ethylene block copolymer
o~ ~R 10. 0 gflO min) was injected under cylinder
. temperature o~ 240C and an injection pres~ure of
~0 ~g~cm2.
In the multi-layer shaet, the thickne~sea of ~he
ou~ar firs~ re~in layer, ~he alumlnum ~oil and ~he
inner fir6t resin layer were 30 microns, ~.5 microns
ar~d 70 microns, re~pectively. The 3econd resin layer
U8
3~
was ~ormed on the outer resin la.yer to a thic}sness
of 0, 7 ~ be open~bility of the rec~ ular cover
thue manufactured is indicated in Table 2, and the
i~jectio~ molda~ility is hown in Table 3~ Table 4
indicates the result~ o compari~on in molding condi~
~io~s ~etween ~xample 16 and Comparison E2ample 8
(described later).
Example 1~
The rectan~ular cover was made by in; ection
0 molding in the ~ame manner a~ tha~ in Example 16 wi~h
~he ~xception th~t, ins~ead o~ "Shoaroma" ~K411C, ~
rasi~ ~repared by adding calcium ca~bide 40% to that
rf~ wa~ u~ed, ~d ~e cylindPr tempexa~ure ~nd the
injec~ion pressure were set to ~60C and 80 kg/cm2,
re~pec~ively. Similar to ~ample 16, the openability
and ~he in~ection moldability of the rectangular cover
were evaluated~ The results of evaluation are A~
indicated in Table~ 2 and 3.
Com~arison E ample 3
~ha injection molding opera~ion ~a~ car~ied out
by using the gate ~1 in ~i~. 20 . For thi8 purpo~e
four bridge~ ~ere ~ormed in ~he slot 60 at in~erval~
( eac:h bridge havin~ a ~idth of 0 . 5 mm ~ . The moldiny
resin was injec~ed in the came manner as tha~ in
Example 16. The results o ~he iniection moldirlg
opexation are as indicated in Tables ~ and 3. The
bridges made it dif~icult to open the cover. Although
the cylinder t~mpera.ture and ~h~ injection pressuxe
~'~S4~7(18
33
were set to ~0C arld 110 kg/cm2, ~espectively, the
moldability wa~ lower than that of Example 16 or 17.
The results of comparis~n in Jnolding condi~ion~
betwee~ ~ompari~on 13~ le 8 and E~ample 16 are
indica~ed i~ ~rable 4.
~5
~he injef~ti~n ~ol~n~ operation ~as conducted ir~
th~ ~ame mazmer a~ that .in ~omparison Example 8, with
the ~xception that, instead ~f ~ate G1, the gate C~2
~ras used. The re~ults of t~e i~j ection molding
opera~ion are indicated in Tables 2 and 3. A~ in
Comparison Example 8, the openabi~lty was low ~d
t~e ~ldabilit~ D lo~. .
A ~ouRd ~over as ~hown in Fig. 2 wa~ ~ormed in
the ~ame manner ~ 'chat ill Example 1~, with ~he
exception tha~ the gate~ G3 and G4 ~iA Fig. 22 ) wer~
used and the cylinder temperature and the irlj ec~ion
pressure were ~et to ~40 C and 55 Xq~cm~, respec~
tively. The result~ are a~ i~dicated in T~bles 2
and 3.
Compari~on Example 10
The injection ~olding opexation was perfonn~d in
the Qame manner a3 tha in Comparison ~xample 8, wi~
the exception that one S~ate ~G3 ~ was used, ~our
bridges 0 . 6 mm ~ n width were Pormed in the sl~t ~0,
and the inje_tion pres6ura was se~ to lQ0 kg/cm2- ~he
re~ults are as shown in Table~ 2 and 3.
~S~7(~13
34
TablP 2 (Openability Evaluation)
,~enabili,~y Evaluatioll
Example 16 O~ening part; opened readily
Wlt~lOUt ~on~i~g burrs.
~xar~ple 17 Di~$~
~xampl~ lB ~itto
Comparison Example ~ Brid~es s~ade it ~iffi~:ult to
ope~ cover.
Comparison Example 9 Ditto
Compari~on Exampl~ 10
Table 3 (Ejection Noldai:~llity E:valua~ion)
M~411C, ~r ~4~ alcium C~bide 40%
Cyli~der l~j ~iDn
Temperature ~re~su~e
~ ~ kq/cm ) Moldab~
Example 16 2~0 60 Very good
Exa3nple 172SO 80 Ditto
Exanlple 182a~0 ~ Ditto
Comparison
Example 8 ~80 110 ~oor
Comparison
Example g 280 110 ~itto
Comparison
~xample 10 280 100 Ditto
.~
~2S47~}8
Table 4 ~Detailed Com~?arison o~
Molding Condltior~)
Compariso
Exam~le 16 Ex~m~le 8
, ... _ __. , . .. _
N~
Cylinder _ _ 2 ~ 3
Temperature 230 240240 220C ~60 280260 240~
I~i ectiorl
Prlmary 2 2
P~e~sure 60 kg/cm 110 kg/cm
In j ection
Seconda~y
Pre6sure 40 kg~ctn 70 kg/cm2
Mold Closing 2 2
Pre~sure 70 l~g/cm 120 k~/~n
15(MR 411C Molding condition)
As is clear from the a~ove-de~cribed Example~ 16,
17 and 18, th~ ~over ~f the inve2~tion ~uld b~ ~pe2~ed
readily without forming burr~ along the edge~ of the
opening part, and were excell~nt in moldability. The
20molding temp~rature aIld the i~jection pre~ure could
be considerably low. Accordingly, the productivi~y
~moldi21g cycle) was high. In addition, everl a mater-
ial mixed with a filter low in mold~bility ~uld ~e
u~ed. Thus, Examples ~6 throu~h 18 were clearly
~5different from Comparison Examples 8 throu~h 10~
In the inven~ion, th~ slot is formed by the
pushing action o~ the metal mold, and there~ore it i5
esirablè that th~ mold closing pressure be l~w (the
low mold closing prefisure increa~ing the durability of
30the metal mold and preventin~ the breakage of the ~lot
formed on the multi-layer sheet)~ The molà clo~ing
~4'~U~3
36
pressure was nnuch lower than that in the Compari~on
~xample~ .
Depending on the molding condi~i~ns, the aluminum
foil may ~e broken at t~e corner in the metal mold
during the in; ection . EIowever, t~i~ problern can be
eliminated by the l~w inj~ction pressure as mentioned
abo~ .
As is apparPnt from the above de6cription, a
can-like con~ainer ' s co~er can be ~nanufa.ctured at
lo relatively low cost by the me~od o~ t,he~invention,
and ha the ~ollowing excellent effects:
( 1 ) As the openi~g part (with the llandle ) a~d
the peripheral pa~t which are ~eyarated by the slot
from each other are fo~ned by u~ing ~he respective
gates, ~he injection moldir~ operation ca~ b~ achie~ed
readily, and ~che multi-layer ~hee~ inserted in t~e
metal mold can be protected f~om being creased or
damaged .
(2 ) ~ecau~e o~ the excellent moldability, the
con~alrler ' ~ cover can b~ molded even wi~h a mRte~ia
low in moldability.
~3 ) The opening part (with ~e handle) and the
peripheral par~ are iqolated from each o~her ~y ~he
clo~ed-ring~haped 610t. therefore, only the multi~
layer sheet i~ cut in opsrling the cover. Thu~, ~he
cor~tairler i s cover of 'che invention i~ excellent in
opena~ility .
~LZS~'~Q~
37
(4 ) ~s ~he treatment layer for facilitating the
peelin~ of the handle i~ prouided, t~e ~a~dle ca~ be
readily peeled of~ the multi-layer ~heet, and ~ere-
fore the container'~ cov~r ~an be opened more readily.
( 5 ) The container ' 8 cover according to ~h~
inven~ion i8 excellent in ~etort c~arac~eristic~ and
with respect to food hygiene consideration~. TherP-
fore, the emplo~me~ o~ ~he container' 8 cover
accordi~g to the inventior~ allows the pr~vision of a
container which can preser~re food for a long p~riod
of ~ime.
~s is apparen~ from th~ above de~cription, ~he
cover acc~rding to the i~venti~ ha~ excellent
~ffect~, and therefore it Aa~ ~ wide range of
~pplications. Typically, ~he cover can be used ~or
manuf~ctu~ing th~ following containers:
~1) Coffee cans, and ~oup can3
(2) Edible (cooking) oil can~, and sea~oning
Call8
~) Packing c~s
~) Motor oil cans
In the embodiments of the invention described
above, in view o~ the openability of the ~an~like
~ ontainer ' ~ cover, the dura~ility of the can-like
25 container, th~ can breaking ~;tLet~th, and the fracture
~trength in the insert molding ~peration, i~t i5 desir~
able tha~ ~e ~irgt resin layer ~ the multi~layer
6heet be loo m~cron~ or less in ~hickne~s, and the gas
-
547Uf~
38
barrier type ba~e material such ~ an aluminum foil be
50 micron~ or le~, p~efera~ly 9 *~ 30 micro~s.
thick~ess o~ the multi-layer sheet, ~spec-
ially the thi~ s~ of ~he metal foil ~aluminumt i~
~itably ~elected in t~e invention, the ca~-like
~ontainer ~:an ~be ~omplete~:y ~ci~er~sd. Recently,
~uch ca~ pollutior~ ha~ occurred. ~we~er, ~qith 1:he
can-like ~ntainer of t~e inven~ion, ~an pollutio~ can
~e ~ ioantly ~educed bec~au~e ~he ~olltainer sf the
invention ~an ~e completely incinerated if` the thiclc-
ne~ o~ the al~num ~oil and ~he re~in ma~erial o~
the mul~i-laye~ 6heet ~e suitably ~elec~ed. ~he heat
ener~y re~uired ~or ~cl~era~mg ~he ~:ontainar i~ ai3
low ~ 5000 to 6000 K~al/kg.
In other embodiment~ o~ the invention, in the
econd resi~ layer forraed on ~e mul~i-layer ~heet,
the opening part and the peripheral part are com-
pletely separated by the slot. In thi~ ~onnec~o~, it
m~y be considered that when the contai21er with ~h~
coYer according to the in~rention iB opened, t~e
openi~lg p~rt may be carelessl3r disposed of. In order
~o prevent ~uch, i . e ., in order to pr~vent ~he
complete remo~r~l of t~e opening part from the cover,
th~ opening part may ~e c~upled to t~e periphe~al part
~hrough coupling part~, narnely, bridg~ o t~e exte
that t:he openabilit~ is not lowered. ~or i2~stanc~, a~
shown in the embodiment o~ Fig. 24, ~he ri~h~-hand
s4~
39
portion of the opening part ~ may be coupled to the
~eripheral part through the bridges.
In the ~bove-described molding method using a
plu~ali~ of gates, the molding temperature ~nd t;he
inj ection pre~ure are con6idera~1y low, ~nd ~112
producticity (molding cycle~ i~ high. ~n addition, in
arcoxdance wi~h the aboYe embodimen~s of ~ inven-
tion, the slot i~ fo~ned by ~e ~ushing ~ctio~ o~ the
metal ~old, a~d therefore it is pre~erable that the
mold clo6ing pressure be low. That is, ~ low molding
clo~ing pres~ure is suitable for i2~crea~ the
durability of the metal mold, preventing damage to the
ba~e m~terial and pr~venting ~reakage of th~ ~l~t.
~n Fig. 25, reIerence numeral 72 d~sig~ates
treatment la~er which is formed to allow the handle 15
to peel off the mul~i-la~r ~heet 64. In openinq the
con~ainer ' s cover, ~;he treatment layer facilitate~
the peeling of the harldle lS ~rom the multi~layer
~hee~ 64 . That is, ~he t~:eat~ent l ayer in as~oci~ion
with ~he slot 60 completely separa~ing t~e opening
part ~û ~rom the periphe~al part 5~ ~unc~ion6 to allow
the cover to ope~ more readily. Any tre~tment of the:
types described abo~e m~y be employed.
Fiq. 26 i~ an enlarg~d plan ~iew of a rolmd co~er
of the pres~3nt embodiment, and Fig. 27 is an enlarged
sectlonal view taken along lin~ Y~' in Fig. 2~,
ln Figs. 6 and 7, parts de ignated ~y the sama
reference numerals as t~ose in Fig~. ~4 ~.nd 25 hat?e
12~4~U~
the same functions, and ~eir description will be
omi~ted~ The round cover i~ ma~ufactured in th~ same
manner as the rectangular cover in ~ig~ 24 and 25, and
it i8 high both in adhesion ~trength and in impact
resi~tance, and can be readily opened. ~n Fi~. 26,
93 ~G3 ) desi~nate~ ~he positiorl of a gate for the
opening part 58, and 94(G4) the position af a gat~ for
the peripheral part 59. me ~pening part and th~
peripheral part are formed indPpendently by using th~
resp~ctive gates G3 and G4.
In order to clarify the e~fects of the inven~ion,
fu~ther Exalr~les and Compari~on Examples. will be
de~cr~ed .
An injection molding ma~hine IS-~OA(30Z~ manufac-
tured by ~o~hiba Co. was u~ed ~o form the rectangular
cover shown in ~ig. 3.
A ~ulti-layer sheet which wa~ fabricat~d by form-
ing ethylene propylene bloc3~ copolymer ( I ) ~M~R 1.1,
ethylene con~ent 4 wt~ layer~ on both sides of an
aluminum foil was u~d. Rubber group gra~rure printin~
ink was applied ~o t~e part of the multi-lay~r sheet
which was to b~ covered by the handle. A xobot wa~
used to ~ixedly hold the thus-trea~ed multi-layer
~heet in the stripper plate of dhe metal mold. Undex
this ~ondition, the inj~ction molding ~peration wa~
carried out. The two ga~es ~1 and G2 ~hown in Fig. 24
were u~d for molding. The 510t w~s formed by ~che
S9~7U8
~1
pushing action of t~e metal mold. The second resin
layer was formed by injecting p~opylene ethylene ~locX
copolymer (II) of MPR 10.0 ~/10 min ~ith a cylinder
~e~perature of 2~0C and an injectio~ pres~ure of
60 kg/cm~.
In the ~ul~i-layer ~hee~, the thi~}cnesses o~ the
outer first re~in laye~, the aluminum ~oil and the
iTmer First resi~ layer were 30 microns, 15 miCrO1~8
~d 70 microns, respectiv~ly. The second ~esin layer
~as ~or~ed on the outer fir~t resin layer'to a thick-
nes~ ~f 0 . 7 mm. lrne openability of the rectangular
cover ~lU5 marlufactured is i~dicated in Table 5, the
p~el~ili~y o~ the handl~ i~ indicated in ~a~le 6, and
~he inj ection moldability is indi~ated in Table 7 .
Table 8 indicate~ ~he result3 o~ co~parison in mold-
ing conditions betwe~ll Example 19 and Comparison
Example 11 (de~cribed below~.
~e3~ ,
P. ~ectangular cover wa~ fonne~ by injec~ion mold~
ing in ~e ~ame ma~e.r as that in Example 19 ~ith t~le
exception that, in6t~ad of the block copolyme~ ), a
~esin prepared by adding calcium caxbide 40% to the
resin was used, and the cylinder temperat~re and the
injection pressure were ~et to 260C and 80 k~n2,
respectively. As in Example 19, the openability o~
the co~r~r, ~he peelability o~ ~he handle, and the
inj e~tion rnoldabili~ were evaluated. The results are
indicated in Tables 5, 6 ~r:d 7.
lZS~'7~)~
42
Ex~l~s 21 throu~h 31
~he in~ection molding operation~ were carried out
in ~:he same marmer a~ tha~ in E~ample 19 s~ith ~he
exc~ption that diff~rerlt multi-lay~r sh~ets and
di~feren~ printing irlXs ~or t~eat~ent layers ) were
emplQy~d el8 i~di~a~ed in l~able 6. . ~rhe ~:o~ers wer~
evaluated for ~he peelability of ~he harldle as indi-
cat~d in~able 6.
~he evaluatio~s of .~he cover o~med by ~ompre~-
~ion f~rming are ~lso indi~ated in Table 6. In 'che
compression ~o~ g, a 50-ton pre88 ma2lufac~ured
Amino P:re~s Co. wa~ used. The ~lalti layer shee~
indicat~d ~ ~able 7 w~s inser~d ~Ln ~he mold~ U~der
~his condi~ion, the compre03ion formillg W~16 carried
out by supp~ying a molten ~econd resin (propylerle
ethylene bloclc co3?olymer of MFR ~.0 g/10 min).
~ompaIi~on ,~x~ll
The injection molding operation -s~Ja~ carried out
by s~ g tlse ~a~e ~3~ in ~ig~ 24. For thi6 purpo~e,
four bridges w~re ~formed in ~he slot 60 at i~tervals
(each bri~ge having ~ widt~ o~ O. 5 mn). The ~nolding
re~in wa~ j ec~ed in the same marmer as that in
Example 19 . The resul~s of ~h~ inj ection molding
operatioa ~re a~ indica~d ill Tables 5 and 7. ~
bridges made it di~fi~ul~ to open the ~ov~r. Although
the cylinder t~mperature and ~he injec'cisn pre~sure
were set to 280~C aad 110 kg/cm~, respectiYely~ the
moldability was lower than that of Exa~aple lg or 2~.
:125~7
43
l The resul~s of compari60n in molding conditions
between ~omparison Example ll and Example 19 ~re
indicat~d in Table 8.
~O~oe~
.
An lnjection molding operation wa~ condu~ted in
-~he ~ame manner ~ i~ Comp~rison Example 1~, with ~he
exceptio~ that, instead of ~h~ gate ~l, the gate &2
was u~ed. The resul~s of ~he i~jection molding ~pera-
. ~ion ~re ~ndicated in T~b1~B 5 and 7. Similar to
1o Compari~on Example 11, bo~h the openabili~y and ~he
moldability were low.
Exa~Dle 32
___
round ~o~er ~ ~hown ~n ~i~. 26 W2~ formed in
~he sam~ manner as that in Example l9, ~ the excep-
tion that the gate~ G3 a~d G~ (Fig. 26) were used and
the cylin~er temperature and the injection pre~ure
were ~et to ~40C and 5S kg/cm2, respe~ti~ely. The
xe~ults ~re a~ indicated in Tables 5, 6 and 7.
An injec~ion moldin~ oper~io~ w~s per~r~ed in
the same mann~ as ~hat in Comparison Example 11, with
the exception that one gate ~G3) was used, four
bridges O.6 mm in width were formed i~ ~he slo~ 10,
and ~he injection pressu~e wa~ lO0 Xg/cm~. The
results are a~ shown in Table~ S and 7.
Com~arison ~xam~la~ 14 throuqh 20
__
Different multi-layer ~heets indica~d in Table 6
were used, and ~h~ injectlon molding op~ration8 or tha
~S~t71)~
44
compreq~ion forming operations were carried out in the
8ame manner as those i~ Examples l9 aIld 21 through 31,
except that no treatment for peeling th~ handle off
the multi-layer 6heet wa~ app~ied. The container'~
cover~ l:hUQ manufactured were evaluated for the peela-
bility o the haTldles as indicated i~ Table 6.
Ta~le 5 (Openability ~S~alllation)
~ .
enabilitY E~aluation
Example 19 O~ening part opened re~dily
- without forming bu~rs.
~xample 20 Ditto
Example 32 Ditto
Comparl~on Exampl~ 11 Bridges made it dif~icul~ to
ope~ c~-v~r.
~omparison Ex3mple 12 Ditto
Comparison Exar~ple 13 Ditto
~Z547~
TabI~ 6
Peeling
Treatme~t
Exampl tTre~tment Forml~ Peel-
No. M_lti-~ayer Sheet layer Method Rbility
19 Outer resl~ layer (1)/
t30 ,u) Injec-
aluminu~ foil/lnner resin lay~r Rubber tio~ Satis-
(15 l~) t70 ~u~series ~olding f~ctory
l~ " " "
21 Re~in (~
altlminum foilfresi~ (1)
Pre~s i~
22 Re~in (2)/s~porlified ethyle~e
acetate vin~l copolymer~ '
(20 ~ njection
re~i~ (2) " moldin8
2~ Re~irL (3) JPVDc1resi~ t3)
(2~ 1~3 ~ n c~
24 ~e~in ~1)/polya~ide/re~i~
(2~
25 Resin tl)~pAN/reain
(20,u)
26 ~ /aluminum foil/resin(l)
27 ~ /aluminum ~oll/resiA~1) " Press
Poly- Inj ec~
28 P~esin tl3/aluminum ~oil/re~i~(13 amide tio~
~30 ~3 ~9 ~) t7a 1l) ~eries molding
Nitro
29 Resin (2)~alumin~D ~oil~resi~(2) c~llulose
(9 ~) 3e~ies " "
Paper
3VResin (3)/al~ oil/resla(3) ~e~l
Pr~s~
Inj ec-
31 Resin tl)/dlwDinu~D foil/re~i~(13 "Cello~ tion
(9 1~) t~ pe" . mol d i~g "
32 OUter ~e3in l~yer (1)~ Flubber
~ 3~ ~3 Beries
aluminum foil/inner resl~ Iayer pri~l:ing
(lS 1l) t70 y) ink
~ZS4~7~
46
Compar~ Peeling
l~on Trestme~t
Exa~ple (Treatme~ ~orming Peel-
No. Mul~i-Layer Sheet layer Method ~bili~y
Inj ec- Not
14 Resin (l)/al~minu~ foil/re~in (l) Not tion peelet
(30 ~) 515 ~) (70 ~ npplied molding off
" " Press
Ini~c~
16 Resin t2)/~ponified e~h~le~e tion
~cet~te vi~yl ~opolymerJre~in t2) " molding
17 Resin (~PVDC~esi~ ~3)
18 Resi~ (1)fpolyamlde~resl~ (1) " "
19 Re9in (l)/PANlre~in (1)
18 ~ ~alumi~um ~oil/re~i~ (l)
t9
Note: Resin (1) ~thylene propylene block copolyme~
MER = 1.I Ethylene content ~ wt~
Resi~ t23 I~PE thigh pre~sure met~od low den~ity
polyethylene~
MI = 5.0 Den3ity 0.920
Resi~ (3~ HDPE (high density polyethylene
MI = l.0 De~sity 0.95~
12S~
47
Table 7 ~jec~ion l~oldability ~valuation)
Cylinde~ Injecti~n
~rempera~re :?xess~e
( C ~ _ (kq/~ Moldablli y
Xxample 19 240 60 ~lery good
Example ~0 260 ~0 ~itto
Example 32 240 ~ Di~tto
Comparison
Example 11 280 110 Poo.r
Compar~on
~xample 12 ~8Q 110 ~Vi~o
Comp~ri~o~
Example 13 2~0 100 Ditto
abae 8 ~De$ailed Co~aris~n Df
. ~YIoldirl~ ~ond
Comparisor
~_ .Exam~le 11
.
N}l EI1 ~2 }I3 N~ H H
Cylinder ~ 1 2 3
Tempera~ure 230 240 ~40 X20C 250 280 260 240C
Injec~ion
Prlmary
Pre~ure -60 kg/cm2 110 l~g/cm~
Inj ection
Secondar~f
Pres~ure 4û kg/cm2 70 kg/~
Mold Clo~in~
Pressure 1~ kg/cm~ 120 lcg~cm2
(M~ 411C Molding condition )
Example~ 33 and 34, and Comparison E}camples 21
throuqh 2~
A rectangular cove~ was fo~ed in th~ ~arne man~er
as ~hat in ~xample 1~, excep~ ~hat a mul~ yer 6heet
consisting of an outer resin layer 70 micron~ in
` ~2S~)8
thickness, an aluminum foil 15 microns in thickness
and an inner re~in layer 70 micron~ in thickness was
u~ed. The xectangular cover thu~ formed was weld~d to
~ contalner body consisting of a bottom and a ~ide
wall to ~orm a sealed can lika container a6 ~hown
in Fig. 1. A drop test was ~pplled $o :the ~an-like
c~ntainer thu~ fonned (Example 33).
A round c~er was formed in the 6ame ~anner as
that in Exa~ple 32 r with ~he except~on that a multi-
layer sheet con~isting of an outsr resin, layer 70
microns in thickne~s, an alu~ oil 1~ micron~ in
thickness, and an inner r~si~ layer 70 micron6
thickrless was used. A~ ~ Example 33, ~:he round covf~r
was used to orm a ~eal~d ca~-like container, and a
drop te t was applied to the containe~ (Exa~aple 3~3.
For comparison, the ~ame multi-layer sheets and
the same ~eco~d resin layers ws:re formed and were then-
3:~onded together by u~ing an uretha~e adhe~iYe to orm
a rectangulax cover and a r~und cover, respectiv~ly.
As in Example~ 33 and 3~, ~Paled can-liXe containers
wer~ ~ormed with these covers, and drop ~eats were
carried out on the can-like containers ~Comparison
Examples 21 and 223.
A ~ealed can-like containex wa~ ~ormed ~si~g ~he
r~ct~ngular cover with bridge~ formed using one gate
as in Comparison ~xample 11. Another sealed can~like
container wa~ formed b~ u~in~ the round cover which
was fabricated in Com~ari~on Ex~mple 13. Drop te~ts
.....
IJ~3
~9
were applied to these ~ealed can-like contaiIlers C~
parison Examples 23 and 24 ) . The mul~i-layer ~heets
used were the ~ame as those in ~xamples 33 and 34.
The content o~ each rectar~gular caIl wa~ about
350 cc in ~olume, and the content of each roun~ can
wa~ a~out 250 cc.
The re~ults cf the~e drop test~ ar~ a~ indicated
in Ta~le~ 9 arld 10.
Table 9
lo I,mp,act Re~istance 50 cm 60 cm 80 c~ 100 cm 120 c~
Example No.:
Exam~le 32 o o o o x
Example 33 o .. o o o o
CoTnparison
Ex~mple 21 o o x x
Colnpari~or~
Example 22 o o o x x
o -- Slo~ not damag~d
x ~- Slot damage~
* -- Repxe~ent~d by a le~el ~cm) fr~m which
the ~aled can-llke container i~
dropped in ~he drop tes~.
As is apparen~ fron~ Table g, the sealed can-like
containers according ~o the invention are hi~h in
~5 impact xesi . tance . It is cvnsidered that this e~ec:t
is due to the ~acts that the resin layers ~re suffi-
ciently weld~d to thc aluminum foil by the~nal
moldinsl, and ~chat, as ~he molding clo~ing pres~ure can
be low, the aluminum ~oil $~ protected from damage
'' i~S~
~o
when the ~lot i~ formed by the pu3hing action of the
metal ~old.
T~le_10
Im~t. Re~stance 50 cm 60 cm 80 ~ 0 ~m 120 ~m
Example No.:
~xam~le ~2 ~ ~ ~
~xam~le 33 o o o o
Compari~on
Exampl~ 23 o x x -
o compari~on
Example 24 o o ~ x
AE W8S descsibed be~ore, in Comparison Exam-
pîe ~3, the can-lik~ ~ntainer was forme~ by using a
~t~n~ula.r ~over whi~h ~1~13 formed by u3ing one ~te
in ~uch a manncr that ~e ~lot had four bridges, and
irl Compari~on Exampl2 24, the can-like contain~ W~l8
fomred by using a round cover which was also fo:rmed by
usinq one gate in such a mann~r tha~ the 810t: had four
bridge~. In each of the above-de~cribed Exampl~s 31
~nd 3~ inj~c~ian pre~sure wa~ hi~h and the mold
closing pressure W~13 al~o high ( qee Table 7 ) . There-
fore, the aluminum foil wa~ damaged, being 3trongly
pre~ed by the metal mold, with the ~e~ults that the
can e con~ainer ~a~ low in imp~ct strength.
3~!
Sealed can~ cor.tainers with rectangular
co~rer~ were fa:bricated in the ~ar~e manner aj that in
Example 3~ except ~hat mul~i-layer 3he~t~; di:Eerent in
oute~ resirl layer, aluminum foil arLd inner resin layer
lZ~i~7t}8
1 ~hicknesses a~ indicated in ~able 11 were u~ed. The
c~tai~er~ thu8 fabricatad were tested for ~an break-
ing ~trengt and openability. The t~t result~ are a~
listed in Table ll:
T~ble 11
I~em Multi-~ayer Sheet. Ca~ Breaking Opena-
~x~mple ~o. Thic~ne~s _ Strenq~h ~cm~ bili~y
Example 3~ 70~15/70 lO0 o
~xample 3~ 30~15/70 80
- Example 37 70/ 9~70 90
~xample 38 30/30/70 90 o
Exam~le 39 60~1~/40 80 . o
Exampl~ 4~ 1~0/15~120 more ~ha~ 15Q x
Example 41 70/~0/70 more ~han 120 x
Note: ~epre~nted by a level ~c~J
~h~ .
Rectansular cover~ were ~ormed in the same m~nner
as that in Example 33, e~cept thak multi-layer ~heet~
di~ferent in aluminum foil thickne~s a~ indicated i~
~able 12 were u~ed. The ~elationships betw2~n the
thic~nes~ o~ ~he aluminum foil and the comple~enes~ o
incineration, aluminum ~oil breaka~e, and openabili~y
.~ were ob~ained as indicat~d in Table 12:
lZS47UB
T~le 12
Aluminum
~oil ~mple~e Aluminum
~Thickne~ Open Tnciner~ Foil
(microns ~ ~y ation Breakaqe
Example 42 9 D ~ O
~xampl~ 4~ 15 o o o
Exa~npl~ 4~ ~0 7 ~ ~
Example 45 50 ~
Example 46 ~0 x ~ o
The alumir~u~n foil t~..i~kne86 iX ~n lmportAn~
~actor affecting ~he abili~y to completely incinerate
t.h~ ~:an, it~ npen~bi~i~.y. ~nd t.h~ ;lumin~m fDil
breakage. ~Io~er, i~ ~e ~ls~um foil i~ at leaRt
15 9 mi~rons in ~hi~lmess, ~he~ fi~ n~ly
block the permeation of oxygen, water, etc.
The thickne~s o~ ~he first re~in layer ~omewhat
affects the o~enability of the container' 8 cover.
However, if the aluminum foil thickn~ss i~ 50 mi~ron~
or less, then ~he container'~ ~ov~r can ~e ea~ily
opened. ~luminum block~ more than fiO microns in
diameter cannot easily be completely inGinerated.
It h~s been con~irmed that if the aluminum foil
thickness is further decreased, then the aluminum foil
2s is lia~le to be broken at its edge por~ions durin~
inser~ion molding, but euch trouble will not occur i~
its thickness is 9 micron~ or more.
As is apparen~ from the above de~criptio~,
r~in~ ~ t~ in~ lik~ ~s~ a~
;l~S~
S3
manufactured a~ a relati~ely low cost, and the can-
like contai~er~ ~hus manu~actured have the following
ex~ellent ef~ect~:
(1) The o~ening pa~t (with the handle~ and ~he
peripheral part are i~olated from each other by ~he
closed-ring-shaped ~lot~ Th~refore, only the mul~i-
layer ~heet is cu~ in openin~ the cover. Thus, t~e
container's cover of the invention is excellent inopen~bility.
10 (2) As the tre~tment l~yer for facilitating the
peeling of the handle is proYided, the handle ca~ be
readily peel~d off the multi~l~yer ~heet, and thère-
fore the container'~ cover ~a~ be opened more ~e~dily.
(3) In the ca~e where the ~econd resin layer i5
formed by u~ing one gate in su~h a manner that it has
th~ bridges over ~he 610t, the inj ection pre~ure i~
unavoidably high, a~ a resul~ of which the aluminum
foil o~ the multi-layer shee~ is d~maged, and the
can-like container i8 low in impact re~ist~nce.
However, in ~he ~bove embodiments of the invention,
bo~h the opening part (including the handle) and the
peripheral part ~eparated by the slot are molded u~ing
at leaat one ~atP. Therefore, the injec~ion molding
oper~ion can be achieved readily, and the multi-layer
shee~ inserted in the me~al mol~ can be prote~ted from
~ein~ creased or damaged, Accordingly, the can-like
container having the container'~ cover according to
12S47~)~
54
the in~rention ~hows a high impa~t resi~t~nce in the
drop t:e~t.
(4) Becau~e of ~he excellent moldability, the
container 1 8 cover C~R be molded e~en wit:h a ma~erial
havin~ a low moldability.
( 5 ) The cont~iner ' ~ cover according ~o $he
invention i~ excellent in r~tort characteristics and
food hygiene. Therefore, the employment o~ the con-
tainer ' s cover a~cordln~ to the in~ention ~:llow~ the
lo pro~ ion of a container which ca~ pre6erve,f~od fsr
a long period of ~ime.
Referring now to Fig. 28, ~ ~urther embodiment o
the i~rentio~l will now ~e descri~ed.
Specifically, Fig. 28 is a perspective ~riew ~how-
ing the body of a rectangular contai~er constx~cted in
accordance with ~he invention. Referenc~ numeral 101
indicates a receptable portion for ~eceiviny contents
such a food. ~he rece~table lO1 include~ a bottom
wa~ 1 10~ and ~ide wall~ 103 extendin~ upwardly f~om
~e four sides of the bottom ~all 102. Should~rs lQ4
extend outwardly from ~he upper e~ges of ~e ~ide
Wall6 103, generally at right aIlgles there~rom.
Fig. 29 ~hows t hQ receptable lol in a plan ~iew
in the unfolded state. Reference numerals us~d ~om
2s morlly in Figs. ~ ana ~ ~enot~ llke elemen~s.
Further, reference numeral 101 ' is a blank or sheet
~ur forming thc re~ tAclc 101 o~ aontain~r body~
The ~heet 101 ' includes a poxtion 102 ' used to form
l~S4'~V8
the ~o~tom w~ll 102 o~ the container ~ody, and por-
tion~ 103 ' whic~ form th~ ~ide walls 103 c~f ~he c~n-
tainer body. Portions 104 ' become the shoulder~ 104
of t~he contair~er body in the folde~l ~t~e.
Fold lines 105 are formed between the bottom wall
portioD, 102 ' and t~e ~ide wall por~io~s 1~3 ', while
fold lines 106 are provided be~ween ~he side wall p~r-
tions 103' snd ~ houlder portins 104',
- An important feature o~ the present invention i8
0 ~he mannPr irl which ~ esB in t~e corner portions i~
acc~mmodat~d when the blank i~ folded to form the
recept~cle 101 o~ ig. 28. ~ore particularly, in
accordance with the i~ventio~, the Qtress i5 accommo-
dated in portions 106, 108, 109 and 110 in a Inanner to
be described.
In Fig. ~9, lllA, lllB, 112~, 112B, 113A, L13B,
114A and ll~B indicate mar~in portion3 of the ~lank.
In accordan~e with the inv~ntlon, these margin por~
tions are ~olde~ ~o fonn ~ucXs ~ two a~ eacn of ~e
~our corners of ~he generally rectangul ar receptacle
101. Taking the maxg~ n portion l~lA a~: an example,
the margin portion lllA i~ folded under the corner
portion 116 by bendiny along fold line~ 115 and 1180
This fonn~ a t~ree-layer tuc~ urlder the portion 116.
The xemaining max~in portions are ~olded in the salae
way. Of course, it is preferred ~hat ~e ~olding of
all margin portions be ~fect~d 6imultaneously, a~
~ill now be dess~ribec7.
12S~7l~8
56
1 ~ig. ~0 ~how~ a female mold and Fig. 31 a male
mold us~d to form the receptacle lQ1 depicted in ~ig.
28. The female mold 119 has a hollow portion 1~1 in
the form o~ a rectangular ~olid at th~ center thereof,
The hollow portion 121 i~ ~urrounded by a solid wall
124 having four corner portion~ 124, 125, 1~6 and 127
be~ween straight ~ide wall portion~ 123, The dimen~
sion~ of the hollow poriton 121 ~re cho6en to ~onform
with the desired dimensions of the container body.
0 The male ~old 1~ shown in Fig. 31 is a g~ner~lly
rectangular-solid member ha~ing ~our ~traiyht wal~
portions 1~3' and fo~r corner portion~ 128, li9, 130
and 131.
TD mold the receptacle 101 of ~ig. 28, a blanX
having fold li~es crea~ed there~n as shown in Fig. 29
i plared ov~r on~ 6ide of the female mold of Fig. 30
with ~he bottom ~ortion 102' centered over the holl~w
portion I21. Then, ~he male mold 12~ of ~ig. 31 i~
depre~e~ against the ~ide of the bl~nk and pre~sed
into the hollow ~ortion 121 ~ the female mol~ 119.
A~ ~hown by the plan view of Fig. 3~, gaps 132,
133, 13~ and 135 axe provided batween the corner por-
tions 12a, 129, 130 and 131 of the mal~ mold 12~ a~d
the respective corner portions 124, 125, 126 an~ 1~7
of th~ fem~le mold 119, while only relatively ~mall
clearanca~ are provi~ed betwee~ the straight wall por-
tions 123' ~f the male mold 1~2 and corxesponding
straight wall portions 123 of the ~emale mold 11~.
.
~2S~7UI~
1 This is done so that the tucks mentioned above are
properly fo.rmed; that is, 50 that the margin portion5
111A, 111B, 11ZA, 112B, 113A, 113B, 114A, and 114B are
folded under the c~rre6ponding corner por~i~ns.
Prefera~ly, ~he blank iS CUt ~o ihe ol~ter 5hape
depicted l~ Fiy. 29 with "~aw-teeth" 136 at ~ach
corner. Further, it is preferable that the ~lank be
dimensioned so ~hat edge lines 137A, 1~7B, etc~, be
aligned with the edge lines 139A, 139B, ~tc.
0 In a further embodiment of thP invention, as de-
picted in Fig. 33, the corn~r portio~s o~ the contai~er
body are gathered as vertical wxi~kl~s. That is, the
receptacle 1~1 as defined by the bot~om wall 1~ ~nd
~ the side walls 103 is arra~g~d Wi~l vertical wrinkles
140 at each of the four corners thereof. Further, if
desir~d, ~he wrinkles may extend onto the shoulders
104.
In either cas~, that is, in the e.~bodiment of
Fig. 29 where the corner portion~ of the receptacle
101 are formed ~y providing two tucks at each corner
portion and ~in the 2mbodiment of Fig. 33 where the
corner portions are ~ormed with ver~ical wrinkles, it
is desirable to hot-melt or e~tend and ~mooth the
resin of the multi-layer body while leaving the metal
foil unex~ended to ~hereby provide a ~mooth surface
and a substantially uniform thiskness. Accordingly,
the thic~ness of the metal foil can be relatively
small, preferably, 40 ~m or lessi while yet providing
l~S~'70~3
5~
1 the container with a sufficient ~treng~h and good
appearanc~. Al~o, cracking and the formation of
pi~-holes are avoided. As an attendant ~dva~tage of
employi~ a ~hin foil layer, particularly, a thin
aluminum foil layer, the container c2n easiiy be com-
pletely incinera~ed, thereby maklng disposal of the
container easier. Moreover, since, with the inven-
tion, it i~ unneces~ary to cut the blank at any poin~
which .fall6 inside the container, there i~ no danger
of cont~ct of the metal with the contents (food) in
the co~tainer. still further, it is gui~e aasy to
provide the container with a ~ufficient dep~h.
To provide ~he cr~ase~ along the fold line~ 105
and 106 a6 described abo~e, a hot-~tamping process or
tha like can be u~ed.
As described above, the container of Fig~. 2B
th~ou~h 33 i9 rectangular. ~owever, it may he penta-
gon~l, hexagonal, or any o~her shape a~ de~ired.
S~7~3~
- 59 -
1 As is apparent from the foregoing, it is preferable to
gather the vertical wrinkles on the non-linear portion
of the side wall portion.
As the material of the multi-layer sheet, as
described above, it is preferable to use at least
two layers, namely, a foil layer and a hot-melt resin
layer formed on at least one side of the foil layer.
Aluminum is preferred for the foil layer~ however,
other materials can be used as well. The thickness of
the foil should be 40 ~m or less, and can even be as
thin as 7 ~m due to the fact that the foil is not sub-
jected to stretching during the formation of the
container.
A variety of resins can be used. However, due to
~S~7U8
1 the preferential use of a hot-melting step, it is re-
commended that a resin which is suitable for ~uch a
process by employed. This is also desirable for at-
taching a cover to the rec~ptacle using a hot-~elt
step, a~ will be de~cribed below in more detail.
Sp~ ic examples o~ suitablc resins i~clude cynthetic
resins such as polyolefins, particularly, ethylene-
propylene c~polymer. Al~hough the thickne~ of the
- resin layer is not especially limited, a thickne~s in
a range of 50 to lQ0 ~m may be employed ~although
thicknesses as small as 40 ~m can be employed.
Next, the structure and method of attachme~t of a
cover to the container w;ll be desrribed.
The materi~l of ~he cover is similar to that of
the materi~l ~f the receptacle, na~ely, the cover is
formed by a 6heet composed of a layer of metal foil
having a layer of hot-melt resin provided on at least
one side thereof. The cover is attached to the con-
tainer body ~y a hea~ ~ealing ~tep whereby the
hot-melt resin of the cover is ~used with ~he adjacen~
hot-melt resin layer of the con~iner body.
Fig. 34 sho~s an example of a container body 141
having a cover 142 joined thereto at peripheral ~dge
portions 143. Fig. 35 i9 a cro~s-sectional ~iew ~aXen
longitudinally ~hrough Fig. 34.
As ~hown in Fig, 35, the cover 142 is comp~sed o~
a c~nter ~oil layer 142 covered ~y ~wo hot-melt resin
layers 145 and 1~7 on th~ opposit~ sides the~eof. The
12S9~ 18
61
l con~ainer body 141 i8 compo~ed of a center ~etal foil
layer 148 -covered by hot-melt resin layers 144 and
149. The layer3 147 and 149, however, may be di~-
pensed wi~h if ~esirPd. Furthermore, a pull top con-
tainer c~er of the type ill~s~rated i~ Fig. 4, 5, 17,
lg, 21, ~3, ~5 ~r ~7 ~bo~e can be e~ployed with
equally good result3.
Next, resu}~s of retorting tests performed on
- ca~ e containers of the present in~ention will be
0 discussed. The retorting test~ were made under the
following condi tion~, wherein a rectanglllar c~ntainar
s dapicted ~ ~ig. 34 ~as filled wi~h W~er and
covered a~ illu~t~ated in Fig. 35:
etortinq Conditlon~:
TeIaperat~lro: 120C,
P~riod: 20 min., and
Pressure: 2 tb 3 kg~2.
The mate~ial used fo~ the container ~ody was a
sheet of ~luminum foil laminated with ethylene-
2 o propyle~e block c~polymer ( C~P - MF~ 1.1 ~d conc~n-
tration of ethylen~3 = 9 wt %~ on both sides of t~e
aluminum foil. The thic3~nes6 of the aluminum foil was
15 ,um, tAe thic3u~ess of the outer resin layer was
30 ~Jm, and the t~icXness o~ the ir,ner resin layer wa
70 ~m. The ~ ture of the cover was similar except
that the thic~ness of the aluminum foil was 12 ~m, ~he
~s~
62
1 thic~ness of ~he inner re~in layer was 70 ym, and the
thicXness of ~he outer resin layer was 12 ~.
Ihe results o~ the ~etorting Tests are pre~ented
in ~able l~ below:
able 13
Water Charqe (cc~ Tuc~s Verklcal Wrinkles ~ *
150 ~K OK NG
1~0 ~X ~K NG
100 ~ ~K r NG
OK ~K N~
OX: No pin h~les ~r separatiD~ ~nd Ietoxtable;
* Redu~ed products; and
NG: Pin holes and ~eparation.
As indicated in Table 13, the amount of water
charged in the container was ~aried from full capacity
(150 cc) to 50% of full capacity (75 ~ ) without
rup-ture or puncture of ~he container, indic~ting that
the container had sufficient stre~gth. As Table ~3
urther indicates, the use of either tuc~s or vertical
wrinkles provides acceptable results, tha~ i9, no
pin-holes are formed and no sepaxati~n occurs with a
container o~ the invention.
Referring now to Figs. 35~ through 35C, a furth~r
modificatio2l of the preqent in~tention will be
described. In accordance with this e.~bodiment, a
-
~z5~7~
63
cover A, forrQed i~ the same manner ~s the cover 14~,
i5 attached ~o a recepta~le B, constructed in the same
manne~ as the contain~r body 141, and the container B
is set in a txay C having ~ ame ge~eral configuIa-
tion as the con~ainer body B. ~ig. 36 is a longi-
tudinal cro~6-6ectional Yiew show1ng the as~ly ~f
the cover A, container body B and tray C.
~he txay can be mad~ from a varie~y of mat~rials,
including plastic~, paper ~r ~oamed poly~yrene.
Alternatively, the pla~tic tray lnay be formed by i~-
jection molding of r~5in ~o ~e ollt~ side of the con
tainer body B. I't i6 preferred that the thickness of
thP t:ray ~e ~ufIicie~t to - support the cont~in~ ~ody
and prevent its deformation duri:t~g tra~portation and
stacki~g.
As ~hswn in Fig . 3 6, the conta~ner body B i~
fitted in khe txay C in such a manner th~t the inner
~ide of t~e latter is adhered to the outer side of the
ormer. For adherin~ the tray ~ to t~e containe~ body
B, an adhesive may be u~ed. Otherwisa, the imler SUrQ
face o ~e ~ray C may be ormed by a hot-mal~ resin
layer and a hot-melt trea~ent applied to join the two
members. S~ill fur~her, it i~ possible fox the corl-
tainer body B to not be adhered to the tray ~, bu 1:
raexely set ~n abut~en~ wi~ e ~me~ Still fur~her,
it is permi~ible in ~ome embodiments to leave a ~;nall
cl~arance ~etWeen the tray C and the c~ntainex body B.
l~S4~7(~
64
To a~semble the cover A, the container body B and
the tray C, first, the tray i3 fed to a mold havin~ an
inner shape generally conforming to the outer shape o
the tray. Next, th~ container body B is prepared as
described above; that is, using t~e ~mbodiment of
either ~ig. 28 or that of Fig, 33. Following this,
the containPr body i~ fixed ~o the tray by pre~exably
a ho~-pressing proces6. To complete t~e assam~ly, the
cover is attached, preferably by heat ~ealing, to the
container body B. of course, prlor to ~he attachment
of the cover C, ~he ~ontainer body ~ i8 charged with
food or the like.
4~08
l A further explanation will be made as to a method
of directly injection molding an outer tray by way of
example of a cylinder-shaped container.
An aluminum-plastic laminate film having an ethylene-
propylene copolymer film 202 of 70 ~ thickness~ an aluminum
foil 201 of 20 ~ thickness and a polypropylene film 203
of 30~ thickness as shown in Fig. 37B, is punched out
for obtaining a disc 204 as shown in Fig. 37A. The
obtained disc 204 of aluminum-plastic laminate film is
placed between a male mold 205 and a female mold 206
having vertical grooves 207 and 208, respectively.
Then, the male mold 205 is pressed into a hollow portion
of the female mold 206, thereby obtaining an aluminum
foil-plastic laminate container 209 having a cylindrical
shape provided with vertical wrinkles as shown in
Fig. 39. The cylindrical aluminum-plastic laminate
container 209 is set on a male mold 212 for injection
molding as shown in Fig. 40. Then, a female mold 213
is aligned with the male mold 212 on which the container
209 is mounted. Under a suitable pressure, ethylene-
propylene block copolymer is injected as shown in Fig. 41.
~` The thickness of the ethylene-propylene block copolymer
layer is about 700 microns. Then, the contacting surface
of the aluminum-plastic laminate container 209 and the
injection molded tray 214 are melt bonded intimately
to each other. Thus, an integrated rigid aluminum
foil-plastic composite container 215 is obtained as shown
~ZS~7L)8
66
1 in Fig. 42. The vertical wrinkles of the container 209
are smoothed by the resin pressure of the injection
molding. Thus, the container has a smovthed inner surface.
After filling the aluminum foil-plastic composite
container 215 with a desired content, a laminate film 216
composed of 12~ polyester ~PET)/20~ aluminum foi1/70
easy peel film is placed on the container 215 as shown
in Fig. 43. Then, the marginal portions are heat sealed
to thereby obtain a completely sealed aluminum-plastic
composite container 217. More specifically, the contai~er
209 and the tray 214 are heat bonded at their flanged
portions to the cover 216 as shown in Fig. 43. The
easy-peel film is made of blended film of ethylene-propylene
block copolymer 50~ and low density polyethylene 50~.
In accordance with the above-described method, the
aluminum-plastic composite container 217 of capacity of
120 cc which was filled with corn soup was retort processed.
The following resu]ts of ability of preserving the content
for a long period were ohtained.
l~S~
67
1 Retorin~ Conditions
Temperature: 120C
Period : 20 min.
Pressure : 2 to 3 Kg/cm2
a) Deformation of Container: none excellent
b) Pinholes : none excellent
c) Separation none excellent
d) Reserving Test ~ no effect excellent
(35C, 3 months, on taste
i.e., equivalent
to xoom temperature,
two years)
e) Falling Test : no crack, excellent
(Under the condition of no damage
20C and -5~C, the (After ten
container was made fallen times)
from l m height to a
concrete.)
f) Heat Seal Strength 2.3 kg excellent
g) Easy-Peel Property readily excellent
opened by
a female
person
With the use of a tray, the can-like container accord-
ing to the present invention is made yet more rigid, thereby
making it possible to use an even thinner metal foil layer
in the container body.
~ arious modifications of the container of the invention
can be contemplated within the scope of the present invention~
For instance, although the container body is described above
7V~3
-
68
1 having shoulders, these shoulders may be dispensed with.
In this case, the cover can be heatsealed directly to
the tray. Moreover, in the case that the container is
to be vacuumed packed, it is recommended that a small
hole be formed in the tray so that the container can be
degasfied to prevent the deformation thereof during
the vacuum-packing process.
Still further, a modification in anticipated in which
a resin similar to that of the outer layer of the container
is directly injected over the inner surface of the container,
whereby the interface between the injected resin and the
container-surface is smoothed. Still another modification
to the cover structure is apparently possible. Namely,
referring back to, for example, Figs. 20 and 21, the easy-
peel cover structure may be used for the can-like containers
shown in Figs. 28 to 43.
This completes the description of the preferred embodi-
ments of the invention. Although preferred embodiments have
been described, it is believed that numerous modifications
and alterations thereto would be apparent to one having
ordinary skill in the art without departing from the spirit
and scope of the invention.
