The present invention relates to a method of making a laminated bottle
according to the characteristics of the preamble of claim 1.
Japanese Patent Laying-Open Gazette No. Hei. 4-267727 discloses a
laminated container having a delaminatable layer designed such that ambient air
is inhibited from entering the container through a mouth while allowing its content
to be di s-charged. This container is composed of an impermeable inner layer and
a squeezable outer layer, wherein the inner layer can be readily delaminated from
the outer layer in which at least one ventilation hole is formed such that the
ambient air can communicate with the space between the layers. In this way, the
inner layer will spontaneously shrink as quantity of the content decreases, with
the ambient air flowing into the space through said hole so that only the outer
layer can restore its normal configuration. Its content remains satisfactory in
quality, from the beginning to end of use, without being impaired by air or light
The direct blow molding known in the art may be an example of the
method of manufacturing laminated bottles of this kind. In this method, a multi-layer
extruder is used to extrude an inner resin layer and an outer resin layer laminated
thereon to form a cylindrical parison. This parison will be placed in a blow forming
mold (and pinched off to provide a closed bottom in a finished bottle), axially
stretched and simultaneously blow molded, to thereby give the finished bottle having
the delam i-natable inner layer.
The abstract of the prior art document JP 04267727 discloses a multi-layer
molded Container, with the inner layer having a higher melting point than the outer
layer and a ventilation hole being formed after injection molding the inner and
In the described prior art laminated bottles, their inner layers should
have each a highly precise wall thickness. In particular, evenness in wall thickness
is more strictly required for profiled or 'modified cross section' bottles such
as elliptic bo t-tles. In order to meet such a requirement, the so-called 'injection
blow-molding' method is preferable wherein a laminated parison that has been prepared
by injection molding will be blow molded.
In many cases, the described laminated bottles are used as containers
for holding therein certain liquids (such as hair-dye) that are likely to change
in their properties due to contact with air. Selection of a resin material for
forming the inner layer must be done carefully lest the content should undergo
any noticeable deterioration even if stored for a long time. Further, the material
is to be selected from relatively soft ones because the inner layers have to gradually
shrink during use. Examples of m a-terials satisfying these conditions may be polyolefin
resins such as a polypropylene and a polyethylene. Polyolefin resins are highly
resistant to chemicals and almost impermeable for gases. Certain medically active
ingredients prone to deteriorate due to expiration of water vapor are protected
from deterioration. A 'PET' or the like resin may be preferred as a material for
forming the outer layer.
Polyolefin such as polyethylene have lower melting points than saturated
polye s-ters such as PET. If the injection-stretching method accompanied by the
subsequent blow-molding step is applied to preparation of a laminated parison wherein
an inner preform is injected prior to injection of an outer preform, then the following
problem would occur. Since the thermal deformation temperature of the already prepared
inner preform is lower than the molding temperature for the outer preform, the
inner preform will probably melt when molding the outer preform, failing to manufacture
useful multi-layer preforms.
A user may close with his or her finger(s) a ventilation hole(s) that
is(are) formed in the prior art delaminatable container for introducing ambient
air in between its layers. Alternatively, a film tag may be adhered in part to
the rim of the ventilation hole so that the tag larger than the hole is disposed
inside the outer layer. Such a kind of valve will allow the air to flow inwards
through the outer layer, but not through the inner layer. With the container being
gripped by the user, the ventilation hole will be closed with his or her fingers
or by the valve so as not to allow any amount of air to leak out from the interlayer
space. Such a depressed outer layer will cause the interlayer air to press in a
centripetal direction the inner layer to exude the content out of the container.
In the prior art of this type, whether accompanied by the valve or
not, the outer layer having the ventilation hole(s) has generally been blow molded
or hot molded before integrating the inner and outer layers one another. Alternatively,
a protrusion jutting from the inner wall defining a blow-molding cavity has served
to directly form a ventilation hole or to form a groove readily transformable into
The prior art method consisting of the steps of preliminarily blow
molding the outer layer and subsequently integrating it with the inner layer does
however require so many steps as raising manufacture cost of the delaminatable
containers and lowering yield thereof. The lug protruding inwardly from the inner
wall defining the blow-molding cavity is described as a means useful to form the
ventilation hole solely in the outer layer. However, there is a possibility that
such a lug would injure the inner layer. The forming of such a preliminary groove
in the outer layer may be possible, but semi-finished containers have to be after-treated
one by one with hand to transform them into the holes. Operation efficiency in
manufacture of those co n-tainers will thus be lowered, raising manufacture cost.
Also disadvantageously, the late opening of the hole in the outer layer is likely
to damage the inner layer.
An object of the present invention is to provide a method of making
a laminated bottle in such a manner that at least one ventilation hole can be formed
easily and surely in an outer layer, without any fear of injuring an inner layer,
and more pa r-ticularly to provide a method of forming at least one hole only in
the outer layer of an injection molded laminated article such as a parison for
use to blow mold a laminated container having the delaminatable inner layer.
This object is solved by the characterizing features of claim 1.
In the method of the present invention, an injection mold may be used
for said injection molding of the inner preform, the mold comprising a core segment
and a cavity segment, the core segment having an injection gate formed therein.
Furthe r-more, injection molding the inner preform may comprise the steps of loading
the outer preform in the cavity segment, subsequently clamping the core segment
and the cavity segment, and finally injecting the second resin inside the outer
preform through the gate in the core segment.
It may be possible that injection molding the inner preform comprises
injecting the second resin through the gate to flow along an inner surface of the
In the method of the present invention, the inner preform may be injection
molded to be integral with a plurality of thickened portions extending vertically
at angular intervals.
Also in the method of the present invention, the inner preform may
be injection molded to have a body that is formed integral with at least one thickened
portion extending in a helical direction.
In the method of the present invention for manufacture of the laminated
bottle having the ventilation hole, a cavity segment and a first core segment for
molding the outer preform may be used for injection molding the outer preform.
Preferably, this method further comprising the additional step of replacing the
first core segment with a second core segment for molding the inner preform, without
removing the outer preform out of the cavity segment, with the additional step
being interposed between the steps of injection molding the outer and inner preforms.
The cavity segment and the second core segment may be used for injection molding
the inner preform. Furthermore, forming the ventilation hole may comprise striking
said pin against the first core segment before the resin of the outer preform cures
at the step of injection molding the outer preform. The ventilation hole preferable
remain closed with said pin during injection molding the inner layer.
Additionally, said pin may be capable of shifting between its projected
position where said pin strikes the first core segment clamped to the cavity segment
and its retracted position where said pin is embedded in the cavity segment.
Also in the method of the present invention, the outer preform may
be held by a lip mold all through a first, second and third step. In this case,
said pin may be c a-pable of shifting between its projected position where said
pin strikes the first core segment clamped to the cavity segment and its retracted
position where said pin is embedded in the lip mold. The pin at the projected position
will clog the ventilation hole but said pin at the retracted position leaves the
Further in the method of the present invention, a first injection
mold may be used for injection molding the outer preform and a second injection
mold is used for injection molding the inner preform. Further, this method preferable
comprises the steps, between the steps of respectively injection molding the outer
and inner preforms, of releasing the outer preform from the first mold, loading
the released outer preform into the second mold, inserting said pin into the ventilation
hole that has been formed in the outer preform. The pin may remain left is the
ventilation hole during injection molding the inner layer.
In the method of the present invention, the parison may be blow molded
such that the stretching for orientation of the preforms is conducted for the portion
thereof located below the ventilation hole.
The present invention now will be described with reference to the
figures 1 to 14 whereby:
- Fig. 1 is a side elevation of a comb shaped product comprising as a part thereof
a laminated bottle that may be manufactured by a method which the present invention
provides in an embodiment thereof;
- Fig. 2 also is a side elevation of the laminated bottle included in the comb
shaped product shown in Fig. 1, from which a cap of the comb-like shape is removed;
- Fig. 3 is an enlarged cross section of a principal portion that is included
in the comb shaped product shown in Fig. 1;
- Fig. 4 is a scheme of the step of fastening mold segments together at an injection
station (before molding an outer preform) in another embodiment of the present
- Fig. 5 is a scheme illustrating an injection step performed at the injection
station (to mold the outer preform);
- Fig. 6 also is a scheme illustrating another injection step performed at the
inje c-tion station (to mold an inner preform);
- Fig. 7 is a scheme of the transfer step of transferring an integrated preform
(viz., parison) at a blowing station;
- Fig. 8 is likewise a scheme of the step of clamping and stretching the parison
at the blowing station;
- Fig. 9 is a similar scheme of the step of blowing and cooling the stretched
parison at the blowing station;
- Fig. 10 is a scheme of the step of ejecting a finished product at an ejection
station so as to take it out;
- Fig. 11 is a plan view of an example of the parison used in the method of making
the laminated bottle according to the present invention;
- Fig. 12 is a vertical cross section of the parison shown in Fig. 11;
- Fig. 13 is a plan view of another example of the parison used in the method
of making the laminated bottle according to the present invention; and
- Fig. 14 is a vertical cross section of the parison shown in Fig. 13.
The present invention provides a method of making laminated bottles
whose p e-ripheral walls are composed each of an outer layer and an inner layer
disposed therein, a resin of which has a lower melting point than that of the outer
layer. The method is characterized in that an inner preform is molded inside the
outer layer by injection molding the resin with the melting point lower than that
of the outer preform that has been injection molded, so as to prepare a parison
composed of the injection molded preforms. According the invention, this parison
will then be subjected, as usual, to the blow-molding step to provide a finished
laminated bottle. In this invention, the inner preform is molded after the outer
preform has been molded. Therefore, even if the inner preform is made of a polyolefin
or the like and the outer preform is made of a 'PET', EVOH' or the like, these
two kinds of resins will not intermix with each other but be demarcated from each
other. Consequently, the delaminatable laminated bottle made by this method has
the inner layer that is readily exfoliated from the outer layer in use, with a
liquid content in this bottle being pr o-tected well from change in its properties.
Both the outer and inner layers of each bottle provided herein may respectively
have bodies and mouths. The body of the outer layer may be squeezable, or alternatively
be rigid in case of mounting a pump in a mouth of the bottle.
In the method of the present invention, the injection molding of the
inner layer may be conducted using an injection mold that consists of a core segment
having an injection gate and a cavity segment. Further, the inner preform may be
injection molded in such a manner that the outer preform is inserted at first in
the cavity segment of the mold, the core and this cavity segments are then fastened
to each other. Finally, the second resin is injected through the injection gate
onto an inner surface of the outer preform, in a case wherein the gate is formed
in and through the core segment. This mode will not make any gate flashes exposed
to the outside, but rather give products an improved appearance. Preferably, the
gate may be formed in and through pointed central region of the core segment.
The method of the present invention is adapted for an application
to manufacture of laminated bottles each having a delaminatable inner layer. For
this purpose, the method may comprise the steps of injection molding the outer
preform and subsequently the inner preform so as to allow the blow molded inner
layer to be delam i-nated from the outer layer in use. The method may also comprise
the step of for m-ing ventilation holes in the outer layer so that ambient air
flows in between the outer and the inner layer. In order to enable the inner layer
to be delaminated from the outer layer after being blow molded and during use,
the wall thickness of the preform may be determined taking into account relevant
parameters such as stretch r a-tio and physical properties of the materials. The
inner preform will be injection molded using a mold that ensures such a wall thickness.
By selecting a proper resin and wall thickness, the thus injection-and-blow molded
outer preform will be capable of squeeze itself.
A stretching rod used to conduct the longitudinally stretching step
will collapse the projection made of the resin forming the inner layer. The longitudinal
stretch conducted at the step of blow molding is effective to press a bottom of
In addition, the injection molding of the inner preform may be conducted
such that a plurality of thickened portions are formed integral with the preform
in such a manner that each portion extends longitudinally and circumferentially.
The blow molded laminated bottles will have each the inner layer that is formed
integral with pillar- or rib-shaped thickened portions. Each of those thickened
portions shows such an improved deformation resistance that the inner layer is
not readily delaminated from the outer layer. Flat regions each interposed between
the linear thickened portions of the inner layer gradually will shrink inwardly
so as to provide the inner layer with uniform shrinkage and deformation over full
height of each bottle. Neither a middle portion of the inner layer nor an upper
end portion thereof (located close to a mouth of the bottle) will shrink sooner
than the lower portion of the layer. Thus, the latter portion will be protected
from being sealed not to exhaust a liquid content. Since the inner preform is injection
molded herein, the forming of such thickened portions can be effected reliably
to give products each having a uniform internal texture.
It is also possible to provide the inner preform with a body-shaped
part that has a thickened region extending in a helical direction. This region
may be a helical protrusion formed integral with the inner surface of the body-shaped
part. Alternatively, a helical recess may be formed in the inner surface of the
outer preform, and then the inner layer is injection molded inside the outer preform
to produce the helical thickened region.
As described above, the present invention is characterized in that
the inner preform having a lower thermal deformation temperature than the molding
temperature of the outer preform is molded therein after molding the outer preform.
In the prior art, wherein a preform of an inner layer has been molded at first,
the inner preform has tended to thermally deform itself when subsequently molding
the outer preform. This drawback is overcome herein, and satisfactory preforms
free from the said d e-fect are now produced. The preform for the inner layer may
be molded after having transferred the other preform for the outer layer into a
further and discrete mold e m-ployed to mold the former preform.
The present invention is applicable to manufacture of the laminated
bottle co m-prising an inner layer laminated on an outer layer and having one or
more ventilation holes formed in the outer layer so as to allow ambient air to
flow in between the outer and inner layers. Such a method may consist of the step
of injection molding a preform for the outer layer, the subsequent step of injection
molding an inner preform inside the outer preform and the final step of blow molding
a parison consisting of such outer and inner preforms. Those ventilation holes
may be formed while injection molding the outer preform, so that the inner preform
may be formed subsequently with pins inserted in the ventilation holes.
According to this method, the ventilation holes are formed when the
outer preform is injection molded. Therefore, such a drawback in the prior art
that the inner layer has been likely to be injured when forming the ventilation
holes in the outer layer during the blow-molding step, is now resolved herein.
Any works for piercing such holes one by one in the injection molded outer layer
are no longer necessary, thus enhancing manufacture efficiency.
Those outer and inner layers may have respective molded configurations
each composed of a body portion and a mouth portion to constitute a bottle. To
protect the mouth portions of the outer and inner layers from separation from each
other, a relatively large thickness of the inner layer may for instance be effective.
The outer layer may be squeezable so as to readily deform itself elastically if
depressed with a user's hand, or alternatively may be rigid in the event that a
pump for sucking the content of bottle would be attached to the mouth portion.
In the method of the present invention, the stratified parison may
preferably be blow molded in such a way that the stretching for orientation of
the outer preform is effected below a portion where the ventilation holes are located.
The ventilation holes in this case are protected well from deformation due to the
step of stretching for orientation, lest should be closed with any amount of the
resin surrounding the holes. Stretching for orientation does not take place around
the ventilation holes, so that the inner layer portions present therearound may
sustain the same wall thickness as that of un-stretched preform. However, the body
of the inner layer for containing the content (liquid content) can however be made
as a thin film in shape and stru c-ture. At the same time, the inner layer portions
around the holes may so thickened as to elastically restore well its natural configuration.
The inner layer constructed to naturally close the ventilation holes will however
be depressed readily by external air pressure. It will deform itself inwardly so
as to open those holes when ambient air is allowed to enter the interlayer space
through them. The ventilation holes b e-have as if they were valves, so that it
is no longer necessary to incorporate any extra or additional valve that would
increase the number of constituent parts and raise manufacture costs.
In this method of the present invention described above, various appropriate
ma n-ners may be employed to make the ventilation holes solely in the outer layer.
For example, the outer preform may be injection molded using a cavity segment and
a core segment, and then be left in the cavity segment. The inner preform will
subsequently be injection molded using the cavity segment in combination with another
core segment, the latter substituting for the first-mentioned core segment. Further,
the ventilation holes may be formed by causing pins to contact the first core segment
before the resin becomes hard at the step of injection molding the outer preform.
The ventilation holes are allowed to remain closed with the pins while the inner
preform is injection molded.
Such a method described above may be conducted using the following
apparatus. Namely, this apparatus will be used to produce a parison to be blow
molded into a delaminatable laminated container that is composed of an outer and
inner preforms and has ventilation holes only in the outer layer at desired portions
thereof. A mold constituting this apparatus may characteristically comprise a cavity
segment and core segments that can selectively be fastened to the cavity segment
so as to mold the outer preform at first, and subsequently mold the inner preform.
Also characteristically, this apparatus further comprises one or more pins in connection
with the cavity segment in order to form the ventilation hole(s). Those pins can
shift the m-selves between their projected position contacting the first-mentioned
core segment and their retracted position embedded in the cavity segment.
Although the pins in the described example for forming said ventilation
holes are located in connection with the cavity segment, they may alternatively
be disposed in a lip segment if the apparatus has same. In this case, the pins
at their retracted pos i-tion will be enclosed with said lip segment.
Further in an alternative method of forming ventilation holes only
in the outer preform, this preform is formed using an injection mold and then removed
therefrom. This outer preform will then be inserted in a further injection mold
for for m-ing the inner preform so that pins equipped in connection with the further
mold are inserted from outside into said ventilation holes that have been formed.
Inner ends of those pins will be brought into flush with the inner surface of the
outer preform, before the inner preform is injection molded.
Such a method described above may be conducted using the following
apparatus. Namely, this apparatus will be employed to produce a parison to be blow
molded into a delaminatable laminated container that is composed of an outer and
inner preforms and has ventilation holes only in the outer layer at desired portions
thereof. This apparatus may characteristically comprise an injection mold for forming
the outer preform and a further injection mold for forming the inner preform. Pins
for forming the ventilation holes are equipped in the first-mentioned mold so as
to be shifted between their projected and retracted positions. The secondly-mentioned
mold comprises pin-shaped stoppers that are to be inserted from outside into the
ventilation holes previously formed in the outer preform.
The method described above addresses parisons that are to be blow
molded to give the delaminatable types of laminated containers. However the present
inve n-tion is not restricted thereto but is applicable to a variety of laminated
articles (such as laminated parisons) that are injection molded and each composed
of two or more resin layers. In other words, the present invention proposes a method
of making ventilation holes solely in an outer layer of an injection molded laminated
product having an inner layer inside the outer layer. The method characteristically
co m-prises the steps of injection molding the outer layer and then molding the
inner layer so that the ventilation holes are formed during the step of injection
molding the outer layer, wherein the inner layer is injected in such a state that
pins are inserted in the ventilation holes.
The parison-forming mold employed in the apparatus and method of the
present invention may comprise at least one cavity segment and at least one core
segment. This mold may further comprise (a) projectable member(s) that is(are)
equipped in the cavity segment so as to contact the side surface of the core segment.
An appr o-priate means may also be incorporated to drive pins preferably serving
as the projectable members.
When molding the outer preform in the described mold, this preform's
portions where the projectable members are temporarily located can not be filled
with a resin for forming this preform. As a result, those portions will define
the ventilation holes penetrating that preform from an outer surface to inner surface
thereof. This means that the ventilation holes as air passages can be formed already
at the same time as the outer preform is molded.
The projectable member incorporated in the mold described above may
be held in and by the lip segment so as to be capable of contacting the core segment's
side face. Alternatively, that member may be held in and by the core segment so
as to contact with the inner surface of the cavity segment or the lip segment.
In any case, the projectable member may preferably be located below a threaded
portion su r-rounding a mouth of the container that will be produced from the preform.
Also, this method of the present invention comprises the step of forming
one or more ventilation holes that penetrate the outer preform from an outer surface
to an inner surface thereof, at the same time as this preform is molded. The ventilation
holes are thus formed already at the step of forming the outer preform. The present
method now eliminates the problem inherent in the prior art that has been injuring
the inner layer when forming the ventilation holes in the outer layer during the
blow molding step. Further, works for piercing such holes one by one in the injection
molded outer layer are no longer necessary, thus enhancing manufacture efficiency.
The delaminatable inner preform is formed herein onto the inner surface
of the outer preform so that, preferably, their portions located below the ventilation
holes are subsequently stretched for orientation.
According to this method, inner layer portions corresponding to the
ventilation holes maintain an original wall thickness, so that each of such relatively
thickened portions may function as a kind of valve cooperating with the ventilation
Thus, manufacture process becomes simpler and less expensive, as compared
with the case of preparing extra and discrete valves.
Also in the present method, an inner end of the projectable member
may be located substantially in flash with the inner surface of the outer preform
when the inner preform is molded using the mold described above.
Due to this feature, a resin forming the inner preform may be prevented
from flowing into portions that are intended to form the ventilation holes in the
In this manufacturing method described above, the ventilation holes
may prefer ably be formed below a threaded portion of the outer preform.
An apparatus for manufacturing laminated containers each having a
delaminatable inner layer may comprise a first injector assembly for molding an
outer preform having one or more ventilation holes that pierce the preform from
an outer to inner surface thereof. The apparatus further comprises a second injector
assembly for molding an inner preform disposed inside the outer preform and capable
of being delaminated therefrom, together with a stretcher assembly for carrying
out the stretching for orientation step for the preforms' portions located below
the ventil a-tion holes. Further, this apparatus may be such that those ventilation
holes are formed in such portions of the outer layer that are located below its
Now some preferred embodiments of the present invention will be described
r e-ferring to the accompanying drawings.
Fig. 1 shows a comb shaped product 22 comprising a laminated bottle
20 having a delaminatable inner layer 20c that has been manufactured by a method
of the present invention. The comb shaped product 22 is suited for uniformly applying
a content such as a hair dye to hair. When a user grips and presses the bottle
20 to be d e-formed, a liquid as the content of the bottle 20 will flow through
a passage not shown but extending through a comb shaped cap 21 and will exude forth
out of se v-eral holes formed in end portions of the comb. If the user stops gripping
and pres sing the bottle 20, it recovers its normal configuration. Such a character
of the bottle 20 is called "squeezability".
As shown in Fig. 2, the bottle 20 has a threaded portion 20a formed
integral with its periphery around the bottle's mouth. As shown in Fig. 3, this
threaded portion 20a is fastened into a mating threaded portion 21a formed in the
comb shaped cap 21 to thereby secure it onto the bottle 20. An outer layer 20b
of the bottle 20 has vent i-lation holes 20d so as to allow ambient air to flow
into a space between the outer layer 20b and an inner layer 20c. Those ventilation
holes 20d may appropriately be formed in an upper portion of the bottle's body
or in a bottom thereof. In the dra wings, the ventilation holes 20d are located
below the threaded portion 20a. In use of the bottle 20, its body will be depressed
by a user with his or her hand or by any other way, before subsequently releasing
his or her hand therefrom. As a result, a m-bient air will flow through the ventilation
holes 20d in between the outer layer 20b and inner layer 20c, so that the inner
layer 20c will remain depressed and shrunk. The bottle body may be depressed later
again while preventing ambient air from flowing into the interior of the inner
layer 20c, and be shrunk to compress air b e-tween said layers 20b, 20c to thereby
squeeze the content of this bottle 20.
As shown in Fig. 3, the bottle 2 is composed of the outer layer 20b
and the inner layer 20c formed therein. The outer layer 20b may be made of a PET
(viz., polyet h-ylene terephthalate), an EVOH (viz., copolymer of ethylene and
vinyl alcohol) or the like. The inner layer 20c is a film delaminatable from the
outer layer 20b and cap able of deformation relative thereto. A material for forming
the inner layer 20c may be a polyolefin resin (such as a polyethylene) of an excellent
gas-barrier property. The inner layer 20c has a melting point and a temperature
of thermal deformation, both lower than those of the outer layer 20b.
The ventilation holes 20d do not penetrate the inner layer 20c but
the outer layer 20b from an outer surface to an inner surface thereof. These holes
may not be closed with the comb shaped cap 21.
The cap 21 is formed integral with a valve 21b facing the mouth of
the bottle 20. This valve 21b may readily open when the content inside the inner
layer 20c is moving into the cap 21, however, prevent the content from moving back
from the cap 21 into the interior of inner layer 20c. Due to this structure, ambient
air is pr e-vented flowing into the cap 21 through holes formed in end portions
of the comb.
When the user grips the laminated bottle 20 to cause deformation of
the outer layer 20b and inner layers 20c, the content inside the inner layer 20c
moves into the cap 21. If the user stops gripping and pressing the bottle 20, it
recovers its normal figure. However, the inner layer 20c maintains its depressed
configuration, and a m-bient air flows into a space between the outer layer 20b
and inner layers 20c through the ventilation holes 20d. If and when the user depresses
the bottle 20 again, these holes are closed by the user's fingers so that the air
between layers 20b, 20c does not leak out of the bottle. Deformation of the outer
layer 20b consequently decreasing its capacity may allow the air to press the inner
layer 20c, subsequently its content thereof will be squeezed out into the cap 21.
Next, Figs. 4 to 10 illustrate molds that are designed to form parisons
7 and to blow mold same in order to produce laminated bottles. Also shown in these
figures are a method of and an apparatus for making the laminated bottles 20. The
lam i-nated bottle 20 in the present embodiment will be produced by the injection-blow-molding
method, wherein the injected parisons 7 are biaxially stretched while blow molding
same. A rotary plate 19 is supported on a frame not shown and intermittently driven
in one way. This plate 19 will cause a lip segment 2 to circulate b e-tween an
injection station (namely, an injection molding apparatus), a blowing st a-tion
(viz., a blow molding apparatus), and a discharging station, sequentially in this
order. This lip segment 2 consists of split halves disengageable sideways from
each other rightwards and leftwards. A driving means not shown will open or close
the lip segment. This segment remaining closed will support the mouth of parison
7 and subsequently support the laminated bottle 20 obtained by stretching the parison
7. The bottom surface of the rotary plate 19 holds the lip segment 2 in place.
At the injection station (viz., in the injection molding apparatus),
the outer and inner preforms 7A, 7B are molded. In this embodiment, the injection
station is d i-vided into a first injection station for molding the outer preform
7A (viz., an apparatus for injection molding the outer layer) and a second injection
station for mol d-ing the inner preform 7B (viz., a further apparatus for molding
the inner layer). In detail, the injection molded outer preform 7A will be removed
at first by opening its mold. Then, this preform 7A will be taken out and inserted
into a mold for forming the inner preform 7B, so that it is injection molded to
provide the parison 7 to be blow molded subsequently.
As described above, the present invention is characterized in that
the inner preform 7B having a lower thermal deformation temperature than the molding
te m-perature of the outer preform 7A is molded therein after molding same. In
the prior art, wherein a preform of an inner layer has been molded at first, the
inner preform has tended to thermally deform itself when subsequently molding the
outer preform. This drawback is overcome herein, and satisfactory preforms free
from the said defect are now produced.
Figs. 4 to 10 show further embodiments in which the inner preform
7B is molded at the same place by exchanging the injection core with another one
after the outer preform 7A has been molded. In this regard, it is to be noted that
in the preceding embodiments the outer and inner preforms 7A, 7B are molded at
discrete and respective injection stations.
Figs. 4 and 5 illustrate the step of molding the outer preform 7A.
In these figures, the injection core 1A, the lip segment 2, and the cavity segment
3 are arranged up and down in this order. After fastening the mold to engage these
segments with each other in a vertical direction, the molten resin is injected
from a nozzle 6. The i n-jected molten resin flows into the cavity through a hot
runner 5 and a nozzle 4. thereof to prepare the outer preform 7A.
The cavity segment 3 comprises a couple of horizontally formed apertures
for receiving two pins 3a. The apertures 3a hold respective projectable members
slidable therein, and those members may be pins 23. A distal end of each pin 23
will protrude inwards to contact the core segment 1A when charging the molten resin
(before or after the beginning of charge). These pins 23 form ventilation holes
20d at the step of molding the outer preform 7A. In this embodiment, solenoids
24 will drive the pins 23 to be retracted and projected. For example, these solenoids
24 each will be actuated with an electric current so as to cause each pin 23 to
protrude t o-wards the cavity segment 3 and contact the core segment 1A. By ceasing
application of electric current to and through the solenoid, each pin 23 will be
retracted away from the cavity segment 3. It is a matter of course that a combination
of a spring for urging the pin 23 towards its retracted position with a means for
supplying a co m-pressed air forcing the pins 23 to protrude may be employed. Alternatively,
a distal end surface of each pin 23 may be recessed corresponding to curvature
of the inje c-tion core 1A.
Fig. 6 shows the manner of molding the inner preform 7B. The injection
core 1A has been pulled out, and another core 1B is subsequently inserted as shown
in this figure. The lip segment 2 and cavity segment 3 are the same as those used
to mold the outer preform 7A. As for the pins 23, they are shown at the same positions
as those shown in Figs. 4 and 5. In other words, their distal ends are arranged
to be substantially in flush with the inner surface of the outer preform 7A. The
injection core's 1B end portion entering the cavity segment 3 has a diameter smaller
than that of the core's 1A end portion, providing a difference between them corresponding
to the wall thickness of the inner preform 7B. Also, the injection core 1B has
a passage for guiding the molten resin into the cavity segment 3 for molding the
inner preform 7B (shown by dotted lines in the figure). As described above, the
distal end of each pin 23 is kept generally in flush with the inner surface of
the outer preform 7A while molding it, so that the molten resin of the inner preform
7B is prevented from flowing into the ventilation holes 20d of the former preform.
After molding the inner preform 7B, the pin 23 will be retracted to
open the mold. Both the preforms 7A and 7B (a combination of 7A with 7B is called
' parison 7' hereafter) are however gripped with and held by the lip segment 2,
even after ope n-ing the mold,
At the blow station shown in Figs. 7 to 9, a blow core segment having
a stretching rod, the lip segment temporarily holding the parison 7, a blow cavity
segment 10 and a bottom segment 11 are arranged up and down in this order. After
engaging them with each other and putting the parison 7 into the blow cavity segment
10, the stretching rod 8 will be driven to have its distal end inserted into the
parison 7. This rod 8 will subsequently stretch the parison 7 in a longitudinal
direction by pressing down the bottom thereof. This parison 7 is simultaneously
stretched also in a transverse direction with a compressed air blown through the
blow core segment 9 and into said parison 7. In this state, the region or portion
(near the lower portion of the container's mouth) where the ventilation holes 20d
are located is firmly held in the segments. Therefore, the stretching for orientation
will not take place in the region adjacent to those ventilation holes 20d. After
completion of this stretching step for orientation, the laminated bottle 20 will
cooled down to give a finished product.
At the discharging station shown in Fig. 10, an ejector rod 23, the
lip segment 2 holding the laminated bottle 20 and a transporting apparatus 24 like
a conveyor belt are arranged up and down in this order. An ejecting foot of the
rod 25 will be fitted in the mouth of bottle 20, before opening the lip segment
2 sideways to lay the bottle on the conveyor 24.
As discussed above in detail, the ventilation holes 20d are formed
at the step of molding the outer preform 7A. This method wherein those holes 20d
are produced when the outer preform 7A is blow molded does therefore eliminate
any problem that the inner layer 20c has been injured in the prior art when forming
the ventilation holes 20d in the outer layer 20b during the blow molding step.
Further, works for piercing such holes one by one in the injection molded outer
layer 20b after co m-pleting the laminated bottle 20 are no longer necessary, thus
enhancing manufacture efficiency. After molding the delaminatable inner preform
7A on the inner surface of the outer preform 7B, the stretching for orientation
of the preforms 7A, 7B is carried out only for a region thereof located below the
ventilation holes 20d. Thus, the inner layer's portion located in a remainder region
where the ventilation holes 20d in the outer layer 7A are present will keep its
original or 'non-stretched' thickness. Such a relatively thicker portion may function
as 'valves' cooperating with those ventilation holes 20d, so that manufacture process
is now rendered simpler and ine x-pensive as compared with the case of preparing
discrete valves. In addition, the i n-ner end of the pin 23 is positioned herein
to be generally in flush with the inner su r-face of the outer preform 7A during
the molding of inner preform 7B. Due to this feature, the resin forming this preform
7B is prevented from filling spaces where the ventilation holes 20d are to be formed
in the outer preform 7A.
In the described embodiment, the inner preform 7B is molded at one
and the same station where the outer preform 7A has been molded, but necessitating
another injection core. Alternatively, such an injection station may be divided
into a first and a second injection stations so that said first station (i.e.,
first injection apparatus) operates to mold the outer preform 7A. In this case,
the second injection station (i.e., second injection apparatus) will operate to
mold the inner preform 7B. In detail, the outer preform 7A just molded will be
removed from the first station's mold, and then transferred into the second station's
mold so as to be laminated with the inner preform 7B. In this case, clogging pins
capable of insertion into the ventilation holes 20d of outer preform 7A may be
employed and incorporated in the mold of the second station for injection molding
the inner preform 7B. The outer preform has to be placed in the second mold in
such a manner that its ventilation holes 20d are e x-actly aligned with those pins
23, which are subsequently inserted from outside so as to have their inner ends
generally in flush with the inner surface of outer preform 7A. The inner preform
7B is laminated on the inner surface of the outer preform 7A.
In an also preferable example, the inner preform 7B has its upper
end portion extending beyond the upper rim of outer preform 7A and bent down there
to reach the upper end of the threaded portion 20a. In this example, the lip segment
2 will be replaced with another or extra lip segment, after cooling down the outer
preform 7A. Such an extra lip segment will provide a clearance between it and the
outer and u p-per regional surface of the outer layer's 7A threaded portion 20a.
The resin forming the inner preform 7B will flow into this clearance to produce
such a bent-down top for this preform.
The pins 23 disposed in the cavity segment 3 in the embodiment described
above may be replaced with another pair of pins 23 contacting the sides of injection
core 1A. Alternatively, these pins 23 may be equipped in the injection core 1A
in such a way as to be in contact with the inner surface of the cavity segment
3 or lip segment 2. Since the lip segment 2 can be split into halves in a transverse
direction, appr o-priate protrusions fixed in and extending in this direction will
contact the core se g-ment 1A when it takes a fastened position. In the example
shown in Fig. 6, the molten resin forming the inner preform 7B is injected through
a passage formed in the injection core 1B. The present method applied to the laminated
container co m-prising the single outer and inner layers 7A, 7B in the described
embodiments and examples, can also be used to manufacture any other type container
whose outer and/or inner layers are composed each of two or more layers or strata.
The injection mold core segment 1B for molding the inner preform 7B
may have at its outer periphery a plurality of vertical grooves (extending up and
down). In this case, several thickened wall portions 30 will be produced on the
preform 7A, 7B to respectively extend up and down at angular intervals as shown
in Figs. 11 and 12. Although the number of those rib-shaped thick portions 30 is
'four' in the illustrated example, it may be 'two', 'three', 'five' or more. A
parison 7 of this configuration will be blow molded to give a finished product
that has an inner layer 20c compri sing vertical thick portions arranged at angular
intervals. If a simply flat inner layer 20c lacking in such thickened portions
is depressed to assume a shrunk appearance in use, then its middle region or upper
end region would be highly likely to be d e-pressed at first to choke the bottle
20 to thereby hinder subsequent discharge of the content. However in the case just
mentioned above, it is sure that the content will be exhausted thoroughly and smoothly.
In another example shown in Figs. 13 and 14, a helical rib-shaped
thickened po r-tion 31 is formed on and integral with the body of inner layer 7B.
This layer 7B of a finished bottle 20 obtained by blow molding the parison 7 will
shrink itself uniformly, lest any intermediate transverse zone perpendicular to
its longitudinal axis should be depressed completely and preceding remainders to
thereby choke the bo t-tle 20.
In the invention, the inner preform 7B having a lower thermal deformation
te m-perature than the molding temperature of the outer preform 7A is molded therein
after having molded said outer preform 7A. One of drawbacks inherent in the prior
art molding the preform of an inner layer at first resides in that the inner preform
is thermally deformed while molding the preform of an outer layer. This problem
is now resolved to provide qualified preforms each composed of a plurality of layers.
Also in the present invention, the inner layer 7B may be formed integral
with a plurality of thickened portions extending up and down at angular intervals,
or thick portions extending in a helical direction. These structures may restrict
shrinkage of the inner layer 7B in such a way that the upper end region thereof
would otherwise be depressed at first to choke the bottle 20. The content of the
container provided herein and free from such a problem will now be exhausted thoroughly
Further, since ventilation holes 20d are formed at the step of molding
the outer preform 7A, an operation for forming these holes 20d only in the outer
layer 7A is readily and surely conducted without injuring the inner layer 7B of
the laminated delaminatable container. Thus, an improvement is achieved not only
in respect of the yield of products but also as to the manufacture efficiency in
production of such delaminatable laminated containers each having ventilation holes
After having molded the delaminatable inner preform 7B on the inner
surface of the outer preform 7A, the stretching for orientation thereof is conducted
for the po r-tion thereof located below the ventilation holes 20d. Thus, the inner
layer portions corresponding to regions where the ventilation holes 20d have been
formed in the outer layer 7A will keep its original or un-stretched' wall even
after the stretching of these layers 7A, 7B. Such a relatively thick portion may
function as a valve c o-operating with each corresponding ventilation hole 20d,
consequently rendering simpler the manufacture process and lowering manufacture
cost as compared with the case of molding extra or discrete valves.
When molding the inner preform 7B, the inner end of the pin 23 employed
herein is located to be substantially in flush with the inner surface of the outer
preform 7A. Thus, the resin forming the inner preform 7B can be prevented from
flowing into portions intended to form the ventilation holes 20d in the outer preform