Note: Descriptions are shown in the official language in which they were submitted.
133215~ :
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This application is a division of
Canadian Pa~ent Application Ser. No. 586,874, ~:
filed December 22, 1988.
This invention relates in general to
new and useful improvements in plastic
containerY, and more particularly to a
container which is blow molded of a polyester
resin and for the most part is highly biaxially
oriented, but has a non-oriented neck finish
for receiving a closure. Such a container must
receive a hot fill product with a minimum of ~ `
shrinkage and diqtortion. ,~
In the past there have been developed
; wide mouth containers wherein the closure / -` `
`~ 15receiving portion or neck finish is highly
biaxially oriented. Further, the neck finish - ~ -
may be subjected to thermal crystallization.
; Such a container and the method of forming the .
same is disclosed in U.S. Patent No. 4,618,515.
~ Thls patent, in turn, is an
improvement on an earlier granted U.S. Patent ,.~-
No. 4,4g6,064.
It~is now desired to form containers .`
having a non-oriented injection molded neck
~fin~ish which~is relatively small in diameter ','.' ,~' "''!
; and which container is p~rticularly adapted for .,~
the packaging of liquids, which liquids must be .`~
placed into the container while hot to provide
for adequate sterilization.
One of the problems of forming a
container~with an injection molded neck finish ~ ~;
is that immediately adjacent to the neck finish
is~a neck to body transition which normally has ,` .
~; low biaxial orientation. This region tends to ~
! ~ 1332155
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distort to a high degree when exposed to temperatures
above 160F. In the past this distortion problem has
been solved by increasing the temperature resistance
of PET through thermal crystallization since the
degree of orientation is not adequate to yield
sufficient strain crystallization to increase the
temperature resistance of PET in this region. One of
the features of this invention is to solve that
problem.
Another problem in the art is the tendency of
the body of the container to shrink such that the
overall shrinkage of the container i5 in excess o~ 1
percent which is the present desired maximum
permissible shrinlsage. In accordance with this
invention, it has been found that through the
application of specific process techniques, the
shrinkage of the container, when hot filled with a
liquid, will be no greater than 1 percent. Further,
the paneled body is so configurated wherein a
conventional label may be wrapped around the body and
be sufficiently supported by the body notwithstanding
the provision of the vacuum panels.
In accordance with the present invention, there
iis provided a preform for forming a blow molded hot
fill container, said preform being formed of a
polyester resin and including a base portion, a body
portion, a neck finish portion and a neck to body
transition, said neck finish portion including a lower
flange immediately adjarent said neck to body
,~ ~ 30 1 transition, said neck to body transition has a portion
of minimum cross section spaced from said flange, said
minimum cross section portion being of a lesser
thickness than said body portion, and said neck to
3~ ~:5 5 ;~
body transition flaring in thickness to said body
portion.
In accordance with the present invention, there
is also provided a method of forming a blow molded hot
fill plastic container, said method comprising the
steps of providing a preform including a base portion,
a body portion, a neck finish portion and a neck to
body transition, said neck finish portion including a
lower flange immediately adjacent said neck to body
transition, said neck to body transition has a portion
of minimum cross section spaced from said flange, said
minimum cross section portion being of a lesser
thickness than said body portion, and said neck to
body transition flaring in thickness to said body
portion, heating said base portion, said body portion
and said neck to body transition to a blow molding
;~ temperature with the heating of the neck to body
transition being heated to a point closely adjacent
said flange, p-lacing the heated preform in a blow
mold, axially elongating said preform at said neck to
body transition, and then inflating said axially
stretched preform to further stretch said preform both
axially and circumferentially in accordance with the
; blow mold.
In accordance with the present invention, there
is also provided a hot fill polyester resin blow
molded container comprising a base, a cylindrical
body, a shoulder portion, and a neck finish, said body
having a plurality of circumferentially spaced and
~l ; 30 ! axially~elongated recessed pressure deformable vacuum
¦~ panels separated by vertical land areas,
`~ ~ circumferential land areas above and below said vacuum
panels joined to said vertical land areas.
133~155
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With the above and other objects in view that
will hereinaftex appear, the nature of the invention
will be more clearly understood by reference to the
following detailed description, the appended claims,
and the several views illustrated in the accompanying
drawings.
Figure 1 i5 an elevational view with parts
broken away of a preform formed in accordance with
this invention.
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Figure 2 is a schematic sectional
view showlng the preEorm o~ Figure 1 initially
being placed in a blow mold.
Figure 3 is another schematic
5 vertical sectional view similar to Figure 2 and
shows a mechanical axial elongation of the
preEorm.
Figure 4 1~ yet another ~chematic ;;~-
vertical sectional view showing the previously
10 axially elongated preform being blow molded to
match the coniguration of the blow mold.
Figure 5 is an enlarged fragmentary ;~
sectional view of that portion of the preform -~
! identified in Figure 1.
Figure 6 is an enLarged fragmentary I -~
vertical sectional view of that Eorm o~ the
~; preform identified in Figure 1. `.
Figure 7 is an enlarged ~ragmentary
sectional view of the upper portion oE the
20 prefform afs ~hown in Figure S aEter the preform d`,~;~"--
has been stretched in the manner shown in ~,", ,,,.~r~,~,"
Figure 3.
Figure 8 i8 an enlarged fragmentary
sectional view of the lower part of the preorm
25 shown in Figure 6 after the axial elongation of ~;d~!`,'"~
the preform as shown in Figure 3. `i
Figure 9 is an.elevational view with
parts broken away and shown in section of a ~ `
con'tainer formed in accordance with this
30 invention in the blow mold as shown in Figure 4
and having a label applied to the body thereof.
Figure 10 is a horizontal sectional ~-~
view taken generall~ along the line 10-10 of
igure 9 and shows further the detai l s of the ~ `
container and the associated label.
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Tllis invention starts with a special
pre~orm 10 which is bes'c illustrated in Figures
1 and 5-8. The pre~orm 10 i8 in jection molded
o a polye~ter resin with particular re~erence
being made to PET (polyethylene terephthalate).
8asically speaking, the various portions o the
pre~orm lO may be ldentif ied as including a
base port~ on 12, a body portion 14, a neck
ini~h portlon 16 and a neck to body transition
18.
Referrin~ now to Figure S, it will be
seen that the upper pax'c of the pref orm 10 i~
il lustrated in detail. ~irst of al l, the
illustrated neck ~lnish portion 16 is in the
form of a conventional neck flnish which may
include external threads 20 for receiving a
closure, a locking bead 22 ~or engagement by a
cl~sure tamper indicating ring or band, and a
lower ~lange 24.
Immedia'cely below the f lange 24 is
the n-3ak to body transition 18. It starts with
an . internal thickening to de~ine a seat 26 for
receiving, for example, a blow nozzle in seated
engagement. Immediately below the neat, the
transition may include a cylindrical part 28.
~3elow the cylindrical part 2P~, the transition
18 downwardly tapers in t~lckne~s externally as
at 30 terminating in a further cylis~drical part
32 o~ minimal cross section. Below the
cylindrical part 32, the transition 18 ~lares
both internally and externally as at 34 to join
the greater thickness body portion 14.
Referring now to Figure 6, it will be
seen that the base portion begins at the lower
end of the body 14 with a radius part 36 which
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,.. ;,,.;
joins a frustoconical part 38 to the body ;~
portion 14. The frustoconical part, in turn,
carrie~: a part spherical bottom 40 which tapers
in thickness from the frustoconical part 38.
It is to be understood that the
pre~orm 10 is formed by injection molding and
when pre~ented to the blow molding apparatus ~ `
~not shown) is at room temperature. A preform,
in a normal blow molding operation, is heated
by a series of quartz heaters which results in -~` -~
the heating of the outer surface of the preform `~
to a higher temperature than the inner surface. `~-~
On the other hand, radio frequency heating has
~- been utilized with the result that the inner -~
surface of the preform is heated to a higher .
temperature. Hybrid heating utilizing a
combination of quartz heaters and radio
frequency heaters has been utilized in the past
~-~ to obtain a uniform temperature throughout the
wall of the preform. Such a heating process is
disclosed in U.S. Patent No. 4,407,651. -~
More recently it has been found that
if the average preform temperature is increased ~ `
to 225 F. as compared to the permissible
average temperature in the 200- 210 F. range
permissible with quartz heating and the 210- ~-
220~F. range permissible with radio frequehcy ;~
heating, shrinkage of a biaxially oriented PET
container is reduced to 2 percent or less and ` ~
by increasing the average temperature of the , `
reheated preform at the time of stretch blowing
to as high as 260F., the container shrinkage ;~
is reduced to on the order of less than 1 -~
percent. ~ -
In accordance with this recent ,~
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1332155 :::
-- 7
development in reheating of preforms, which is
the subject of a pending U.S. application, the
preform 10 will be reheated first utilizing a
quartz oven or like quartz heater with this
first reheating treatment resulting in the
outside surface temperature of the preform ,~
ri.~ing to on the order of 240F. while the
inside surface of the preform is only slightly ` .:~.
heated to a temperature on the order of 120F. j:~
The temperature of the center of the body wall
of the preform is only slightly greater than .
the inside surface temperature and is on;the
order of 140F. The initial reheating time is
on the order of 14.5 seconds. ~.
15After the first quartz reheating, the
~; reheating is discontinued and the preform is ~
permitted to equilibrate for a period of time .~.
;~ on the order of 5 seconds. The temperature of
the outside surface of the preform body
continues to increase to a temperature on the
. order of 250F. and then begins to cool down to
a temperature on the order of 230F. At the ~:
same time, the temperature of the center of the
preform body remains generall.y constant while i~ - -
25the temperature of the inside surface of t.he `; -~.
preform body increases gradually to a
. temperatu~e on the order of 135P., the
temjperature of the inside surface..of t.he
preform body approaching that of the center of ,
- :30 the preform body. ~. . .~......... .... .. .y~ Thereafter, it is preferred that :.-
further reheating of the preform be also.by way.
of a quartz heater for a reheating period. The ~:~
~ time of this further quartz reheating is on the .~-~
~ 35order of 12.5 seconds and during this second
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1332155 ~ : ~
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period of quartz reheating, the temperature of .~
the exterior surface of the preform body ~ :
continu~s to rise above the temperature of the
center of the preform body and the inside
surface of the preform body. The exterior
surface temperature ris.es to on the order of
350F. while the inside surface temperature
810wly gradually rises to a temperature on the ..
order of 180F. and the temperature at the '~
center of the preform wall slowly rises at a .~,~
slightly greater rate to a temperature on the .~ .
order of 220F. ,.~:
After the second quartz reheatlng, ~u ;
~ once again the temperature of the exterior .,,~
-~ 15 surface of the preform body i~ much greater
than that of the interior surface and the .. ~
temperature at the center of the preform body
has also gradually increased above that of the
interior surface of the preform body.
The preform body is immediately ~
thereafter urther reheated by way of radio .
:frequen~cy heat~ing. While the temperature of ; .
the outside~surface of the preform body rises .
onl~y sl:lght~l~y during the radio frequency
25~- heati:ng~. the~heating of the inside surface of . ~m.~ .
the preform.body very rapidly increases from
,~1? ~ the temperature generally on the` order ~of
160 F. to a temperature slightly greater than
3~0 ~. The time~of radio frequency heating is ~~
-.~Y~ 30~ on the order of 2 seconds. During this time
ther~e~is o~nly~ a minor increase in the
temperatur~e:o$ the preform ~ody at the center
f~`~ of the cross section thereof to a temperature .
`';`.~:; : on the order of 240F. Thus the temperature:of
:35: the center of the preform body cross section is ; ~.:
:; ~,','``.~'
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.,~ , ~ ,., .; . . .
-~ - t~3?~55
g
the lowest and the temperatures of the inside
surface and outside surface are greater.
At this point, the application of
external heat to the preform is stopped and the
5 preform is directed into a blow mold, as will
be discussed hereinafter, and blow molding
steps are initiated with there being a total
lapse of time on the order of 6 seconds.
During these 6 seconds, there is a second ~;
equilibration of the preform.
uring the second temperature
equilibration, the temperature of the outside
surfaces of the preform body will rapidly
decrease to a temperature on the order of, but
15 below 280F. At the same time, the temperature
on the inside surface of the preform body will
continue to increase and then taper off to a
temperature on the order of 350F. In a like
manner, the temperature of the preform at the
m 20 center of the body cross section will rise and
then taper off at a temperature on the order of
260F. It will thus be seen that the ~;~
temperature at the center of the cross section
r ~ ; of the preform body is still the lowest, but
! 25 the temperature of the outside surface is only
slightly greater. -;~
Inasmuch as crystalliæation is a
factor of temperature and time and sincelthe
time during which surface crystallization may
occur after reheating of the preform to its `~
maximum temperature is reduced, the desired
high reheat temperature may be obtained in
accordance with this reheating method without
the undesired surface crystallization.
It is known to utilize a stretch rod
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to axially elongate a preform within a blow
mold to assure the complete axial elongation of
the preform. However, normally a similar rod
is utilized solely for the purpose of
maintaining the preform in a centered
relationship with respect to the blow mold as
the preform is inflated. However, in
accordance with this invention, it is proposed
to utilize the normal centering rod initially
as a stretch rod, but prior to the introduction
of a blowing gas into the preform. Thus, as is
schematically shown in Figure 2, the preform
10, duly heated in the manner described above,
is placed within an open split blow mold,
generailly identified by the numeral 42 in a
conventional manner. After the blow mold 42
has been closed, as shown in Figure 3, instead
of immediately beginninq the inflation of the
preform, the customary centering rod 44 is
directed down into the preform 10 and engages
the bottom part 40. The rod 44 is utilized to
elongate the preorm on the order of 25
percent, as i~ shown in Figure 3. The results
of this elongation of the preform 10 are best
shown in Flgures 7 and 8~ Since the reheating
of the preform 10 stops on the order of 2mm
below the flange 24, and since the preform is
supported against axial movement within the
~ ~blow mold by the flange 24, there is no
;;~ '!`30 deformation or elongation of the neck finish
portion 16. On the other hand, since the
;~central part of the neck to body t~ansition 18
is of minimum cross section, it will be seen
that there will be considerable elongation of
35 the neck to body transition 18. This will
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occur primarily in the cylindrical part 32 but
will also occur partially within the downwardly
tapering portion 30 and the downwardly flaring
portion 34. Further, and rnost particularly, it
will be seen that when the transition 18 is
axially elongated, it will also neck down so as
to as~ume a radially inwardly directed bowed
configuration thus in effect reducing the
diameter of the central part of the transition .-
18. Becau~e of the radially inwardly directed
bowing of the transition 18, it will be seen :~
that in the blow molding o~ the preform 10
within the blow mold 42 there will be a greater
stretching of this portion of the preform in
th.e hoop direction~
With reference to Figure 8, it will~ ~.
:~ be seen that since the base portion 12 of the
~; preform 10 is also heated to a high :
temperature, when it is engaged by the stretch
rod 44, its resistance to thinning will not be
~: ~ as great as that of the body 14 so that there
~`~ will be an elongation of the base portion 12 as
is best shown in Figure 8. This elongation
;~ wiLl be primarily in the radially outer portion
~:~ 25 of the body part 40 and in the frustoconical
part 38 with the result that there will be a :~
newly formed body part ~6 which is generally ~-.
hemispherical together with a cylindrical part:~
; ,; . 1 48 in accordance with the diameter of the
stretch rod 44. Finally there will be an
upwardly flaring generally frustoconical part
~; 50 which joins the cylindrical part 48 to the
body 14 by way of a curved part 52.
The preform 10, having been elongated
on the order of 25 percent, is now ready for
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the introduction of a blow gas so that the
preform lO may be inflated in the customary
manner to match the configuration of the blow ;
mold 42. If desired, during the inflation of ~-
the stretched preform 10, the stretch rod 44
may be permitted to follow the axial elongation
of the preform during inflation so as to make
certain that the base portion 12 of the preform
remains centered relative to the blow mold.
The inflation of the preform 10 within the blow
mold 42 re~ults in the formation of a container
in the form of a bottle generally identified by
the nu~eral 54.
It is to be understood that the shape
of the container or bottle 54 is also critical
in the hot fill shrinkage thereof. As will be
apparent, the bottle 54 will have a neck finish .
which is identical with the original neck ~-~
finish 16 of the preform 10 including the
flange 24 and a portion of the preform
immediately below the flange which wa~ not
heated, as previously described. This portion
~; is generally in accordance with the previously
described part 28 of the preform.
The bottle 54 also includes a ~i-
downwardly and outwardly sloping shoulder
portion 56 which is formed from the previously
stretched neck to body transition portion 18.
The shoulder portion 56 in conventional ~ ~
container constructions is generally of a low ~;
orientation and is gradually formed during the 'j'~
inflation of the preform. However, inasmuch as
the shoulder portion 56 is defined by that part ,
of the preform which was very r`apidly ;
mechanically stretched followed by the
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13.~?155
- 13 -
inflation of the preorm, the shoulder portion
56 has a high strain crystallization.
In accordance with the design
configuration of the illustrated bottle 54, the
shoulder portion 56 is connected by a radius 58
to an upper body portion 60 which flares
slightly outwardly and downwardly. The upper
body portion 60 terminates in a radially
inwardly directed rib 62 which, in turn, is
connected to a general}y cylindrical main body
portion 64. The main body portion 64 includes
upper and lower cylindrical bands 66, 68 with
the body portion 64 between the bands 66, 68
including a plurality of radially inwardly
r~cessed vacuum pressure panels 70. Each
;~pressure panel 70, as is best shown in Figure
9, is of a vertically elongated rectangular
configuration with rounded corners and i5
generally chordal in configuration. Each
pressure panel 70 is reinforced against
deformation by a plurality of transverse
horizontally extending radially recessed ribs
72 which are also of an elongated rectangular
outline,~ but the elongation being in the
25~ horizontal or circumferential direction.
Adjacent pressure deformable vacuum
panels 70 are separat~ed by a vertically
elongated land area 74. Each land area 74
extends between the bands 66, 68 and is
xelnforced by a vertically extending, radially
inwardly directed rib 76.
;~The bottle 54 also includes a base 78
which include~ a ribbed recessed bottom 80
which is joined to the body 64 by a rounded
`~35 base portion 82. The ribbed bottom, which is
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- 14 13321~S
best shown in Figure 10, may include Pive
circum~erentially spaced, radiating downwardly
directed ribs 84 which are defined by the base
configuration of the blow mold 42.
As is be~t shown in Figure 9, the
bands 66, 68 are recessed radially inwardly a
slight distance with respect to the lower part
of the rib 62 and the rounded portion 82 of the
base portion 7~. This permits a conventional,
low cost, full wrap label 86 to be applied to
the body portion 64 in a protected position.
A~ ls clearly shown in Figure 10, the label 86
bridges the recessed pressure deformable vacuum
panel 70 so as to give the bottle S4 the
appearance of one wherein the body portion 64
i~ cylindrical.
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It is to be understood that due to
the specific high temperature of the preform 10
which is possible in accordance with the
heating procedure ou~lined above, and because
of the speci~ic stretch ratio of the blow
bottle 54 with respect to the preform 10 in
both the axial and hoop directions, the
resultant bottle 54 has in the body portions
the reof a 28-30 percent sidewa l 1
crystallization which is a stress induced
crystallization as opposed to being a
temperature induced crystallization. Further,
because of the specific cross sectional
; 30 configuration of the body portion 64 as well as
the specific stress induced crystallization of
the shoulder portion 56, when the bottle 54 is
hot filled with a liquid at a temperature on
the order of 180- 185F., the shrinkage of the
bottle 54 by volume will be no qreater than 1
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- 15 _ 13321.~S
percent, i.e. the volumetric shrinkage should
be between 0 and l percent. Thus the bottle
54, when hot filled with a heated liquid, will
maintain this configuration. Further, because
the neck finish l6 is non-oriented, it will be
subjected to heat deformation. I~owever,
because the neck finish 16 is injection molded
and relatively thick, it will be able to
with.stand the momentary heating thereof to a
relatively high temperature without deformation
which will prevent the closing and sealing of
the bottle 54 utilizing conventional closures,
particularly screw threaded closures.
It will also be noted that the
recessed bottom or base portion 80 is of a
relatively thick wall configuration and will ,;~
resist deformation when the bottle 54 is filled ~
`; with a heated liquid.
Although only a preferred embodiment ~
;~ 20 of the container and the method of forming the
same, including a preferred embodiment of ~;~
preform, has been specifically described and ~;
illustratedr it is to be understood that minor
variations may be made in the invention without
departing from the spirit and scope of the
invention as defined by the appended claims.
3b
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