U.S. patent application number 12/251663 was filed with the patent office on 2010-04-15 for plastic bottle with a mouth.
This patent application is currently assigned to The Coca-Cola Company. Invention is credited to Kenshi Matsuoka.
Application Number | 20100089863 12/251663 |
Document ID | / |
Family ID | 41314525 |
Filed Date | 2010-04-15 |
United States Patent
Application |
20100089863 |
Kind Code |
A1 |
Matsuoka; Kenshi |
April 15, 2010 |
PLASTIC BOTTLE WITH A MOUTH
Abstract
To provide a plastic bottle whose weight can be reduced without
sacrificing strength of a bottle mouth, the plastic bottle is
provided with a bottle mouth having a circumferential wall,
including a threaded section formed on an outer circumferential
surface of the circumferential wall, a support ring protruding from
the outer circumferential surface below the threaded section, and
punched sections formed on the circumferential wall.
Inventors: |
Matsuoka; Kenshi; (Tokyo,
JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Assignee: |
The Coca-Cola Company
|
Family ID: |
41314525 |
Appl. No.: |
12/251663 |
Filed: |
October 15, 2008 |
Current U.S.
Class: |
215/252 ;
215/329 |
Current CPC
Class: |
B65D 1/023 20130101 |
Class at
Publication: |
215/252 ;
215/329 |
International
Class: |
B65D 41/00 20060101
B65D041/00; B65D 41/04 20060101 B65D041/04 |
Claims
1. A plastic bottle, comprising: a bottle mouth having a
circumferential wall, including: a threaded section formed on an
outer circumferential surface of the circumferential wall; a
support ring protruding from the outer circumferential surface
below the threaded section; and punched sections formed on the
circumferential wall.
2. The plastic bottle of claim 1, wherein the punched sections are
positioned away from threads of the threaded section and from the
support ring.
3. The plastic bottle of claim 2, wherein the punched sections are
positioned between the threaded section and the support ring.
4. The plastic bottle of claim 3, wherein the bottle mouth is
sealed by a cap fitted with a releasable tamper evident band, and
wherein the outer circumferential surface is provided with a bead
ring protruding at a position away from the punched sections
between the threaded section and the support ring, the tamper
evident band being configured to be severed and dropped onto the
support ring when the bottle mouth is opened by manipulating the
cap and to remain on the bottle mouth by the bead ring and the
support ring.
5. The plastic bottle of claim 4, wherein the bottle mouth is
provided with a maximum diameter section having the largest
diameter at the outer circumferential surface below a base side of
the bead ring, the maximum diameter section being configured to be
covered by the tamper evident band when the bottle mouth is sealed
by the cap, and wherein the punched sections are formed on the
outer circumferential surface from a lower edge of the maximum
diameter section to an upper edge of the support ring.
6. The plastic bottle of claim 5, wherein columnar sections having
the same maximum diameter as the diameter of the maximum diameter
section are formed between the maximum diameter section and the
support ring adjacent to the punched sections and the maximum
diameter section, wherein a difference between the maximum diameter
in the maximum diameter section and the minimum diameter in the
punched sections is not more than 3.0 mm.
7. The plastic bottle of claim 5, wherein the punched sections are
formed in line symmetry at uniform intervals in the circumferential
direction, and the columnar sections having the same maximum
diameter as the diameter of the maximum diameter section are formed
adjacent to the maximum diameter section between two adjacent ones
of the punched sections.
8. The plastic bottle of claim 4, wherein sections connecting each
of the punched sections and the columnar sections are etched with
an arc having a center of a radius of curvature located inside of
the bottle mouth.
9. The plastic bottle of claim 3, wherein each of the punched
sections has an arced cross-sectional shape.
10. The plastic bottle of claim 3, wherein the threaded section
includes at least one continuous thread strip around the outer
circumferential surface of the circumferential wall.
11. The plastic bottle of claim 10, wherein the bottle mouth has a
wall thickness at the threaded section thinner than a wall
thickness at a section below the threaded section.
12. The plastic bottle of claim 1, wherein the plastic bottle is
formed by a biaxial stretching blow molding.
Description
TECHNICAL FIELD
[0001] The present invention concerns the structure of a mouth of a
plastic bottle.
BACKGROUND
[0002] Plastic bottles represented by PET bottles are produced
through biaxial stretching of preforms that are formed through
injection molding, etc. In recent years, reduction in the weight of
plastic bottles has proceeded out of concerns that include resource
conservation and cost reduction. The strength of the bottle must be
maintained for its commercial value when reducing its weight.
[0003] Japanese Kokai Publication Hei-2001-113589 discloses a
bottle in which the body section and shoulder of the bottle overall
are thinner while the strength is maintained by reserving essential
thickness of the bottle mouth. A threaded section for screw
tightening of the cap is formed to protrude at the mouth of the
bottle, and a flange-shaped support ring is formed to protrude
below the threaded section.
[0004] Japanese Kokai Publication Hei-2004-26201 and Japanese Kokai
Publication Hei-2008-143588 discuss a bottle in which the tamper
evidence is maintained. A bead ring is formed between the threaded
section and the support ring in the mouth of such a bottle. The
tamper evident band is severed from the entire cap when the cap is
manipulated to open this type of bottle, and it is ultimately held
so as not to be detached via the bead ring and the support
ring.
[0005] In recent years, a desire has arisen for weight reduction of
the mouth as well from the perspective of resource conservation.
Heat resistance is imparted through hot crystallization processing
so that the mouth of the bottle disclosed in Japanese Kokai
Publications Hei-2004-26201 and Hei-2008-143588 does not deform due
to hot fill packing, but this does not contribute to weight
reduction. Furthermore, Japanese Kokai Publication Hei-2001-113589
merely discusses weight reduction of the body section but does not
adequately reduce the weight of the mouth. In fact, while the body
section of the bottle exemplified in Japanese Kokai Publication
Hei-2001-113589 is 0.5 mm thick, the mouth is very thick, at 2.2
mm.
[0006] If the same method as that applied to the body section were
adopted to reduce the weight of the bottle mouth as stated in
Japanese Kokai Publication Hei-2001-113589, the strength would
decline markedly because the overall mouth would become too thin.
Consequently, there is a risk of deformation or splitting of the
mouth upon manipulation of the cap to open the bottle. Furthermore,
there is a risk of the mouth part that is set in a chuck (for
example, the circumferential wall section between the support ring
and the bead ring in Japanese Kokai Publications Hei-2004-26201 and
Hei-2008-143588) being damaged or the tamper evidence suffering
damage if the mouth is set in a chuck in the course of bottle
production prior to capping.
SUMMARY
[0007] The objective of the present invention is to provide a
plastic bottle in which the weight of the bottle mouth can be
reduced without sacrificing the strength.
[0008] A plastic bottle is provided with a bottle mouth having a
circumferential wall, including a threaded section formed on an
outer circumferential surface of the circumferential wall, a
support ring protruding from the outer circumferential surface
below the threaded section, and punched sections formed on the
circumferential wall.
[0009] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The accompanying drawings, which are incorporated in and
constitute a part of this specification, illustrate an exemplary
embodiment of the invention and together with the description,
serve to explain the principles of the invention.
[0011] FIG. 1 is a front view of a plastic bottle pursuant to an
embodiment;
[0012] FIG. 2 is an oblique view showing enlargement of the mouth
of the plastic bottle of FIG. 1;
[0013] FIG. 3 is a front view of the mouth of FIG. 2;
[0014] FIG. 4 shows a semi-cutaway view showing the state of
closure of the mouth shown in FIG. 2 by a cap; and
[0015] FIG. 5 shows a cross-sectional view cut along line V-V in
FIG. 3.
DETAILED DESCRIPTION
[0016] Reference will now be made in detail to an exemplary
embodiment of the invention, which is illustrated in the
accompanying drawings. Wherever possible, the same reference
numbers will be used throughout the drawings to refer to the same
or like parts.
[0017] In one embodiment, a plastic bottle is provided with a
bottle mouth having a circumferential wall, including a threaded
section formed on an outer circumferential surface of the
circumferential wall, a support ring protruding from the outer
circumferential surface below the threaded section, and punched
sections formed on the circumferential wall.
[0018] Since the thickness is reduced in a section in the present
invention, the weight can be reduced without sacrificing strength
of the bottle mouth in comparison to uniform reduction of the
thickness. Furthermore, obstruction of resin fluidity during
formation of the bottle mouth is inhibited and the preform molding
properties are not damaged.
[0019] Preferably, the punched sections would be positioned away
from the threads of the threaded section and from the support
ring.
[0020] More preferably, the punched sections would be positioned
between the threaded section and the support ring. By so doing, the
thickness would be greater and the weight could be reduced while
keeping strength in mind since sections are punched out between the
threaded section and the support ring.
[0021] Here, use of the following structure would be desirable when
the bottle mouth is opened by a cap fitted with a releasable tamper
evident band. Specifically, a bead ring should protrude at a
position away from the punched section between the threaded section
and the support ring on the outer circumferential surface of the
circumferential wall. Furthermore, when the bottle mouth is opened
by manipulating the cap, the tamper evident band would be severed
and would then fall onto the support ring where it should remain on
the bottle mouth so as not to be detached via the bead ring and the
support ring.
[0022] The weight of even a bottle that has tamper evidence can be
reduced by punching with such a structure.
[0023] More preferably, a maximum diameter section that has a
maximum diameter outer circumferential surface at the bottle mouth
among the outer circumferential surfaces of the circumferential
wall should be provided at the lower edge on the base side of the
bead ring as a section engaged by the tamper evident band when the
bottle mouth is opened by the cap. The punched sections may be
formed from the lower lip of the maximum diameter section to the
upper lip of the support ring at the outer circumferential surface
of the circumferential wall.
[0024] The tamper evidence can be maintained since the strength of
the section engaged by the tamper evident band is secured in such a
structure. Furthermore, chuck engagement is possible without
modifying existing production facilities since the maximum diameter
section is located where the chucking is generally engaged in the
course of production. Moreover, existing specifications can be used
by any shape of the part of the tamper evident band (for example,
the tab discussed below) since a maximum diameter section is
present. In addition, a die can be easily opened for injection
molding in comparison to formation on the inner circumferential
surface of the circumferential wall since punched sections are
formed on the outer circumferential surface of the circumferential
wall.
[0025] More preferably columnar sections having the same maximum
diameter as that of the maximum diameter section should be formed
between the maximum diameter section and the support ring adjacent
to the punched sections and the maximum diameter section. The
difference between the maximum diameter at the maximum diameter
section and the minimum diameter in the punched sections should be
not more than 3.0 mm.
[0026] Sections that can be engaged by a chuck can be broadly
secured stably in such a structure since the columnar sections
having the same diameter as the lower side of the maximum diameter
section can continue on a given surface. Furthermore, the fluidity
of resin can be secured during injection molding of the bottle
mouth by setting aforementioned maximum value (3.0 mm). Conversely,
there is a high possibility of resin not reaching the columnar
sections, resulting in molding failure, when the maximum value is
exceeded.
[0027] In a separate mode, the punched sections would be formed in
line symmetry at uniform intervals in the circumferential
direction, and columnar sections having the same maximum diameter
as that of the maximum diameter section would be formed adjacent to
the maximum diameter section between mutually adjoining punched
sections.
[0028] Since a plurality of columnar sections in addition to the
punched sections have line symmetry in such a structure, centering
is easily completed when setting columnar sections in chucks. An
additional advantage is that molding balance is improved during
injection molding of the bottle mouth because of line symmetry, and
molding failure does not occur when opening the die because
injection molding is employed.
[0029] In another example, the sections that connect each of the
punched sections and the columnar sections would adopt an arc whose
curvature radius R centers on the inside of the bottle mouth.
Damage to the connecting sections accompanying engagement on a
chuck can easily be inhibited in such a structure.
[0030] In another embodiment, the transverse section of the punched
sections would be arc shaped. For example, the concentration of
stress at the punched sections due to force in the inward direction
of the bottle mouth would occur less in comparison to a trapezoidal
shape.
[0031] Also, the threaded section may have at least one continuous
thread strip about the outer circumferential surface of the
circumferential wall. By so doing, the reinforcing effect of the
mouth due to the threaded section could be enhanced in comparison
to the use of a three strip screw or in comparison to a single
non-continuous thread strip having a bent slot or a single strip
that does not complete one rotation of the outer circumferential
surface of the circumferential wall.
[0032] The thickness of the section of the circumferential wall of
the bottle mouth where the threaded section is present may be
thinner than the thickness of the section below the threaded
section. In one example, the thickness of the section of the
circumferential wall of the bottle mouth where the threaded section
is present may be more than or equal to 0.8 mm and less than or
equal to 1.3 mm. Deformation and cracking can be inhibited even
with thin pieces since a reinforcing effect is attained with one
thread strip in a piece that is thin in order to reduce weight.
[0033] The plastic bottle is explained in an embodiment of the
present invention with reference to the appended figures. In the
following explanation, the direction where the bottle mouth is
present is up and the direction where the bottle base is present is
down. The height signifies the length along the central axial
direction (vertical direction) of the bottle. The transverse
section shape represents the transverse section shape along the
plane (transverse plane) orthogonal to the central axis.
[0034] Plastic bottle 1 (hereinafter abbreviated "bottle 1") has
mouth 2, shoulder 3, body section 4, and base 5 from the top, as
shown in FIG. 1. These sections (2, 3, 4, and 5) are formed
integrally, and include the bottle wall for holding a beverage
within. The beverage could be any non-carbonated beverage including
water, green tea, or fruit juice. However, the liquid packed in
bottle 1 in other embodiments may be a carbonated beverage or food
such as a sauce.
[0035] Bottle 1 may consist primarily of thermoplastic resin such
as polyethylene, polypropylene, or polyethylene terephthalate, and
it may be molded by stretch molding such as biaxial stretch blow
molding.
[0036] One example of the course of bottle production is explained.
First, thermoplastic resin is injected into a die to complete
injection molding of a preform. This preform has a mouth having
exactly the same shape as that of mouth 2 and a tubular section
having a bottom that is connected below the mouth. Injection
molding is followed by opening the die for the mouth in the
transverse direction, opening the die for the tubular section in
the vertical direction, removing the preform and then setting it in
a blow molding apparatus. Only the tubular section of the preform
is heated in the blow molding apparatus, the tubular section is
stretched in the vertical direction by a stretching rod, and the
tubular section is stretched in the transverse direction by blowing
in compressed air to complete formation of shoulder 3, body section
4, and base 5. Serial molding of bottle 1 is completed by so doing.
Subsequently, the bottle is washed, disinfected, and packed with a
beverage. Mouth 2 that functions as the injection orifice for the
beverage is then sealed with cap 6 (See FIG. 3).
[0037] Mouth 2 has cylindrical circumferential wall 10 that opens
upward, as shown in FIGS. 2 to 4. Inner circumferential surface 12
of circumferential wall 10 extends without bumps in the vertical
direction. On the other hand, threaded section 16, bead ring 18,
and support ring 20 protrude on outer circumferential surface 14 of
circumferential wall 10. Threaded section 16 exists over the upper
half of circumferential wall 10 while bead ring 18 and support ring
20 exist below threaded section 16 at a predetermined
separation.
[0038] Threaded section 16 can use either two thread strips or
three thread strips, but a single thread strip, which is more
difficult to loosen and which has higher strength, is structured in
this embodiment. The thread crest of threaded section 16 continues
at a single height in the lengthwise direction without formation of
a so-called bent slot. The length of the thread crest should be
more than one rotation of outer circumferential surface 14,
specifically, the effective angle should exceed 360.degree.. Here,
that would be approximately 720.degree. (for example, 650.degree.
for the complete threaded section +70.degree. for the partial
threaded section), which is about the length of two
circumferences.
[0039] Bead ring 18 and support ring 20 protrude outwardly over
outer circumferential surface 14 in the circumferential direction.
Top 3a of shoulder 3 is linked to the lower edge of support ring 20
on the base side (See FIG. 4). Bead ring 18 and support ring 20 are
also denoted by different terms (for example, flange section,
etc.).
[0040] Here, seen from the perspective of the magnitude of the
thickness of circumferential wall 10, circumferential wall 10 has
thin section 10a and thick section 10b that is thicker than thin
section 10a, as shown in FIG. 4. Thin section 10a is the tubular
section wherein lies threaded section 16 on the outer
circumferential surface while thick section 10b is the tubular
section below threaded section 16. Bead ring 18 exists on the upper
edge of thick section 10b while support ring 20 exists on the lower
edge of thick section 10b. Thin section 10a and thick section 10b
each have uniform thickness in the vertical direction (See FIG.
4).
[0041] The size of each thickness of thin section 10a and thick
section 10b should satisfy the required strength for mouth 2
overall. When considering the thickness of one, the thickness of
the other is determined. In general, since many parts of the
circumferential wall between bead ring 18 and support ring 20 are
held in chucks in the course of production of bottle 1, the
strength must be secured relative to the chucks. In light of this
point, mouth 2 in the embodiment secures the strength by
constructing the circumferential wall section in question from
thick section 10b while the remaining circumferential wall section
is structured from thin section 10a while maintaining consideration
of the securing of strength. The reinforcing effect of thin section
10a is enhanced by structuring threaded section 16 that exists on
thin section 10a from a single continuous thread strip.
[0042] In one example of the dimensions in this structure, the
thickness of thick section 10b preferably would be approximately
2.0 mm while the thickness of thin section 10a preferably would be
0.8 mm or more and not more than 1.3 mm, more preferably 1.0 mm or
more and not more than 1.2 mm. Securing the strength of thin
section 10a solely through the reinforcing effect of threaded
section 16 becomes difficult when the thickness of thin section 10a
is under 0.8 mm, but the molding cycle increases and the production
efficiency of the preform declines. On the other hand, weight
reduction of mouth 2 becomes insufficient when the thickness of
thin section 10a exceeds 1.3 mm. Both securing the strength and
weight reduction are realized by setting the thickness of thin
section 10a at 1.0 mm or more and not more than 1.2 mm.
[0043] The structure of the punched sections of thick section 10b
whose weight has been reduced by partial thickness reduction is
explained next. The punched structure becomes effective through
combination with aforementioned structure (demarcating
circumferential wall 10 vertically between thin section 10a and
thick section 10b), but weight reduction is attained even when not
combined (specifically, when the thickness of circumferential wall
10 is constant in the vertical direction).
[0044] Thick section 10b has maximum diameter section 22 on the
lower edge on the base side of bead ring 18, and a plurality of
punched sections 24 as well as a plurality of columnar sections 26
are found on the lower side of maximum diameter section 22. Maximum
diameter section 22 is the tubular section with the outer
circumferential surface of maximum diameter in outer
circumferential surface 14 of circumferential wall 10. For example,
it has a height of 1.4 mm. Columnar section 26 is the section
having the same maximum diameter and thickness as that of maximum
diameter section 22. It continues on a given surface of maximum
diameter section 22. Connection section 28 that connects punched
section 24 and columnar section 26, as shown in FIG. 5, adopts an
arc whose curvature radius R centers on the inside of mouth 2 so as
to connect the two in a gently-sloping manner.
[0045] A plurality of punched sections 24 are formed on outer
circumferential surface 14 with line symmetry at uniform intervals
in the circumferential direction from the lower lip of maximum
diameter section 22 to the upper lip of support ring 20. Then,
columnar sections 26 are formed between adjoining punched sections
24, 24. A total of eight punched sections 24 and columnar sections
26 are alternately aligned in this embodiment, but the number is
not restricted to eight.
[0046] As shown in FIG. 5, the transverse section shape of punched
section 24 has an arc shape curving to the inward direction of
mouth 2. R (radius of curvature) of the arc shape of punched
section 24 should be in the range of 5 to 50 mm, preferably 30 mm.
Undercutting occurs since it is too small when R is under 5 mm, and
removal of the preform from the die becomes more difficult.
Conversely, an adequate effect of punching for weight reduction is
not attained since R is excessively large when it exceeds 50
mm.
[0047] The center of punched section 24 is thinnest and it
gradually thickens toward both edges. The thinnest section has the
section of smallest diameter in punched section 24. The thickness
can be equal or equivalent to the thickness of aforementioned thin
section 10a. However, the minimum thickness of punched section 24
need not be equivalent to the thickness of thin section 10a so long
as fluidity of resin as well as strength can be secured during
molding. The difference between the smallest diameter of punched
section 24 and the maximum diameter of maximum diameter section 22
should be not more than 3.0 mm at the diameter, preferably in the
range of 1.5 mm to 2.0 mm. Thermoplastic resin may not reach both
edges of punched section 24 during injection molding of the preform
when it exceeds 3.0 mm. Conversely, the flow of thermoplastic resin
during injection molding is not obstructed and molding failure can
be avoided if it is not more than 3.0 mm.
[0048] Next, cap 6 is explained with reference to FIG. 4.
[0049] Cap 6 fits on mouth 2 through rotational manipulation to
close the aperture of mouth 2. Cap 6 need not have a tamper
evidence property (a function of displaying fraudulent opening),
but a tamper evidence property is present in the example explained
here.
[0050] Cap 6 has cap body 30 and tamper evident band 32. Cap body
30 has round cover section 36 that covers the top of mouth 2 and
cylindrical section 38 that covers the sides of mouth 2.
Cylindrical section 38 is the section that extends down from the
peripheral edges of cover section 36. Threaded section 40 that
engages threaded section 16 of mouth 2 is formed on the inner
circumferential surface of cylindrical section 38.
[0051] Tamper evident band 32 is connected to the lower edge of
cylindrical section 38 via severable bridge 42. Tab 44 (engagement
section) facing up and inward is formed on the lower inner surface
of tamper evident band 32. Tab 44 engages steps that are demarcated
by bead ring 18 and maximum diameter section 22.
[0052] Removal of cap 6 is prevented by tab 44 that engages bead
ring 18 and maximum diameter section 22 in the closed state of
mouth 2 by cap 6 shown in FIG. 4. In this state, when cap 6 is
turned in the direction of opening, bridge 42 is broken, tamper
evident band 32 is severed from cap body 30, and it falls onto the
upper surface of support ring 20. The upper edge portion of tamper
evident band 32 that had fallen then rests on bead ring 18 and it
is held so as not to readily release in the vertical direction by
support ring 20 and bead ring 18. In further detail, the downward
movement of tamper evident band 32 that remains on mouth 2 after
opening is controlled by support ring 20 while its upward movement
is controlled by tab 44 that contacts bead ring 18.
[0053] Exemplary operating effects of mouth 2 of bottle 1 in the
embodiment explained here are explained below.
[0054] 1. Perspective of Strength and Weight Reduction
[0055] Punched sections 24 are formed to partially reduce the
thickness of those sections that are often thick in consideration
of application of a chuck (the circumferential wall section from
bead ring 18 to support ring 20). By so doing, even while weight
reduction is realized, the strength of mouth 2 is not sacrificed in
comparison to the case in which the overall thickness is reduced.
Furthermore, the overall weight of mouth 2 can be reduced while
preventing deformation or cracking of thin section 10a, as stated
above, since thin section 10a, which has a reinforcing effect, is
set in mouth 2.
[0056] Furthermore, a part having the same thickness as that of the
existing mouth can be partially left in mouth 2 since maximum
diameter section 22 is found at the section that engages tamper
evident band 32. Tamper evident properties can be maintained and an
existing cap 6 can be used since the strength of maximum diameter
section 22 is secured by so doing.
[0057] Furthermore, the concentration of stress at the punched
sections 24 due to force acting in the inward direction of mouth 2
accompanying depressurization within 1 would not readily occur
since the transverse section shape of punched section 24 is an arc
shape. Similarly, even if bottle 1 is pressurized through filling
with a carbonated beverage, the concentration of stress at punched
section 24 would be resisted. Accordingly, decline in the strength
of punched section 24 can be inhibited in comparison to the case in
which the transverse section has a trapezoidal shape.
[0058] 2. Perspective of Chuck Application
[0059] Mouth 2 is set on a chuck when a preform is moved along a
blow molding apparatus in the course of production of bottle 1.
Even if existing production facilities are used unchanged, chucks
may be used without deformation of mouth 2 since maximum diameter
section 22 is present at the part that the chucking is engaged in
many cases.
[0060] Furthermore, chuck application can proceed stably even if
the chuck should shift in the vertical direction since columnar
section 26 continues without steps on the lower side of maximum
diameter section 22. In other words, columnar section 26 itself can
be utilized as a part that has a chuck applied. Furthermore,
centering is easy when columnar section 26 is set on a chuck since
a plurality of columnar sections 26 are disposed with line
symmetry. In addition, scratching when a chuck is applied can be
inhibited since connection section 28 positioned at both edges of
columnar section 26 has a radius of curvature R.
[0061] 3. Perspective of Fluidity of Thermoplastic Resin and Die
Release
[0062] The fluidity of thermoplastic resin during injection molding
of preforms affects the productivity of bottle 1. The fluidity of
resin to form punched section 24 is easily secured since punched
section 24 is punched in arc shape. Furthermore, obstruction of
molding properties during molding of mouth 2 is readily prevented
since thick sections are uniformly installed in the direction of
resin flow. In addition, opening of the die for mouth 2 in the
transverse direction is facilitated since punched sections 24 are
formed on outer circumferential surface 14 of circumferential wall
10, in comparison to their formation on inner circumferential
surface 12 of circumferential wall 10. Furthermore, the molding
balance is improved and mold failure is inhibited when opening the
die in the transverse direction since the disposition of punched
section 24 and columnar section 26 is in line symmetry.
Accordingly, the productivity of bottle 1 can be enhanced.
[0063] The design of the structure of aforementioned mouth 2 can be
suitably modified so long as it does not deviate from the scope of
the present invention. For example, punched section 24 can be
formed on the upper side of bead ring 18 instead of on the lower
side of bead ring 18. Furthermore, punched sections 24 can be
formed in the section that extends outward from the thread crest of
threaded section 16, specifically, in the circumferential wall
sections of spiral shape between adjacent thread crests.
Alternately, punched section 24 may partially engage the end of the
thread crest of threaded section 16. These cases would be ideal
applications to the formation of circumferential wall 10 of mouth 2
at a single thickness. Furthermore, punched sections 24 can be
formed on inner circumferential surface 12 or outer circumferential
surface 14 of circumferential wall 10, but formation on outer
circumferential surface 14 would be preferable from aforementioned
perspective of ease of removal from a die. In addition, heat
resistance can be imparted to mouth 2 through heat treatment of
mouth 2 involving hot crystallization.
[0064] It will be apparent to those skilled in the art that various
modifications and variations can be made in the plastic bottle of
the present invention without departing from the scope or spirit of
the invention. Other embodiments of the invention will be apparent
to those skilled in the art from consideration of the specification
and practice of the invention disclosed herein. It is intended that
the specification and examples be considered as exemplary only,
with a true scope and spirit of the invention being indicated by
the following claims.
* * * * *