Note: Descriptions are shown in the official language in which they were submitted.
CA 02569812 2006-12-07
WO 2005/123518 PCT/EP2005/052799
1
Plastic bottle and process for affixing a shrinkable label thereon
FIELD OF THE INVENTION
The present invention relates to a plastic bottle, suitable to be covered with
a
sheet of shrinkable plastic material, and to a process to cover said bottle.
PRIOR ART
A problem occurring in the field of containers for foods, and more
particularly in the
plastic bottle field, is how to protect the content from external agents, as
well as
from the loss of components through the walls of the bottle, for example
carbon
dioxide in carbonated drinks. Among the external agents that cause worsening
in
the taste and nutritional properties of the content are oxygen and light, both
ultraviolet and visible; for example, foods such as milk are particularly
susceptible
to the action of light, which even in just two days causes deterioration of
the
proteins which imparts a typical disagreeable flavour. Moreover, light,
especially at
wavelengths ranging from 200 to 800 nm, causes the destruction of some
vitamins
typical of these foods. For this reason bottles are commonly made of
thermoplastic
materials (such as PVC and PET) covered with a heat-shrinkable plastic film.
The
film provides adequate barrier properties for gases such as oxygen and carbon
dioxide and against physical agents such as ultraviolet and visible light. For
example, it is often considered necessary to screen light with a wavelength
ranging from 200 to 800 nm in particular. DiffeTent types of film are used.
These
can be films with several layers, for example co-extruded, of different
thermoplastic materials or of the same material treated in different ways, for
example a layer of expanded material and one or two layers of non-expanded
material. Often the outermost layer is printable: in fact, the covering can
have the
functions of a label.
The covering film is shaped like a sleeve, for example by extrusion thereof
directly
in this shape or by joining two sides of a film in an appropriate way, for
example by
gluing or heat-sealing. A cylinder of this film is suitably positioned around
the
bottle, for a height adequate for the covering to be obtained, for example by
gluing
the two edges of a film surrounding the body of the bottle. Usually, the
bottle has a
lower part, also called body, with a more or less constant section except for
projections or grooves, and an upper part which tapers towards the neck of the
bottle. The shrinkable film can also cover this part, providing the height of
the film
CA 02569812 2006-12-07
WO 2005/123518 PCT/EP2005/052799
2
is adequate. Application of heat causes the film to shrink, adapting to the
surface
of the bottle, comprising the upper tapered part, if required. There are
different
ways of applying heat, for example hot air can be blown, for example at 250 C
for
seconds, while the bottle is made to rotate.
5 Some plastic bottles have a body with a section which is not round, for
example a
quadrilateral section, with rounded edges; this type of bottle is appreciated,
as well
as for aesthetic reasons, also due to the fact that more botties can be stored
in a
smaller space compared to bottles with a round section, containing the same
volume of liquid. In this case, the tapered part also usually has a similar
section to
the body and must be connected to the cylindrical neck of the bottle in a
suitable
way.
A problem with this type of bottle lies in the fact that the tapered part and
the
connection area are usually critical areas as regards adhesion of the
shrinkable
film. This is because, in the direction along the longitudinal axis of the
bottle,
usually an axis of symmetry, the length to be covered differs at the edges of
the
quadrilateral section with respect to the centre of the sides. This determines
poor
adhesion of the film in the part below the neck of the boitle, where shrinkage
must
be maximum, causing non-uniform thickness of the covering and the possible
formation of creases.
Therefore, the object of the present invention is to identify forms of plastic
bottles
having a body with a section which is not round, for example triangular or
quadrilateral, which allows good adhesion of the covering also on the tapered
part
and also extending in proximity to the cylindrical neck, that is, in the areas
above
the body of the bottle.
SUMMARY OF THE INVENTION
The problem set forth above has been solved, according to the present
invention,
by means of a plastic bottle having a longitudinal axis, a body with a cross
section
which is not round, an essentially cylindrical neck, a tapered part starting
from said
body and interposed between said body and said neck, wherein the boundary
between said body and the tapered part has convexities facing in a
longitudinal
direction towards said neck in the points in which it is at a minimum distance
from
said longitudinal axis, and facing in the opposite direction in the points in
which it is
at a maximum distance from said longitudinal axis.
CA 02569812 2006-12-07
WO 2005/123518 PCT/EP2005/052799
3
Preferably said body has an essentially parallelepiped form, therefore with a
base
of a form which is not round. It can be a parallelepiped with an essentially
polygonal base, preferably quadrilateral, more preferably square and
preferably
with rounded edges.
According to a preferred aspect, the tapered part is a convex surface. It is
preferably a surface of revolution about the longitudinal axis, or it can have
a cross
section similar in form to the cross section of the body, but less
accentuated, at
said boundary.
The invention therefore relates to a bottle, as described above, which allows
perfect covering thereof with a heat-shrinkable film with uniform thickness
and
without the possible formation of creases in said film, and to a process to
cover
said bottie.
LIST OF FIGURES
Figure 1 schematically represents a front view of a bottle according to the
present
invention.
Figure 2 schematically represents a view rotated through 45 with respect to
the
longitudinal axis of the bottle in Figure 1.
Figure 3 schematically represents a longitudinal sectional view of the detail
in
Figure 2 enclosed in the circle A.
20- Figure 4 schematically represents a plan view of a bottle, sectioned at
the
cylindrical neck below the finish, according to a different aspect of the
invention.
Figure 5 schematically represents a bottom view of a bottle according to the
present invention.
DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION
Figure 1 shows a front view of a bottle according to the present invention. It
has a
longitudinal axis 1, which, preferably, is essentially an axis of symmetry of
the
bottle; in the present description, unless otherwise specified, cross section
is
intended as a section according to a plane perpendicular to said axis 1, while
longitudinal section is a section according to a plane containing said axis 1.
The bottle comprises a body 2, as said with a cross section which is not
round, in
the case specified essentially squared (a certain convexity of the sides
towards the
outside is possible), with rounded edges. This can be appreciated by comparing
Figure 1 with Figure 2, where rotation through 45 makes it possible to
observe the
CA 02569812 2006-12-07
WO 2005/123518 PCT/EP2005/052799
4
maximum width D1 of the body 2, while in Figure 1 the minimum width D2 is
shown. The body 2 extends between a base 3, which closes it at the bottom and
has a form and characteristics which can be of a known type, and the tapered
part
from which it is delimited by the boundary 4, which can, for example, be a
more
5 or less rounded edge, a projection or a groove. The cross section of the
body 2 is
preferably essentially constant along the axis 1. It is understood that in any
case
there may be narrowings or widenings due, for example, to grooves or
projections,
such as the grooves 6, or other elements, such as contoured areas to
facilitate
grip, writing or decorative elements, which are commonly found on plastic
bottles.
The bottle has an essentially cylindrical neck 7, at the end of which is an
opening 8
to gain access to the content. There may be other structures such as the
finish 9,
a more or less flanged shaped annular projection which is usually provided
around
the neck of many types of plastic bottle, the thread 10 to allow screwing of a
cap,
and any others deemed suitable.
The tapered part 5 starts from the boundary 4, between the body 2 and the neck
7.
According to a preferred aspect, this tapered part 5 has the form of a surface
of
revolution. This determines the typical course of the boundary 4 between the
tapered part and the body 2, with the convexities 11 facing upward in a
longitudinal direction, namely towards the end of the bottle with the neck 7,
where
the wall of the bottle is at a minirnum distance from the axis 1, that is, in
the case
of a body 2 with a polygonal section, in the middle of the sides, and the
convexities
12 facing downward, that is towards the base 3 of the bottle, where the wall
of the
bottle is at the maximum distance from the axis 1, thafi is at the edges 13 of
the
body 2. The convexities 12 can be shaped as a consequence of the radius of
curvature of the edges 13 which are preferably rounded; they will tend to
become
cusps if the edges 13 are sharp.
According to another aspect of the invention it is possible that the tapered
part 5 is
not a surface of revolution or at least not for its entire extension. In this
case, it can
preferably have a cross section, at the area involved by the boundary 4,
similar to
the cross section of the body 2, for example essentially polygonal, in
particular
quadrilateral, with convex sides towards the outside and with rounded edges,
although less accentuated, which means curvature of the sides, convex towards
the outside, more marked and edges more rounded; this produces an intermediate
CA 02569812 2006-12-07
WO 2005/123518 PCT/EP2005/052799
form between the form of the cross section of the body 2 and a circular form.
This
again determines a course of the boundary 4 as described above, but less
accentuated than in the case of a tapered part 5 having the form of a surface
of
revolution. The tapered part 5 can have an increasing inclination with respect
to
5 the axis 1 as it approaches the neck 7, that is being essentially convex,
naturally
with the exception of grooves or other elements as already mentioned for the
body
2.
Advantageously, between the neck 7 and the tapered part 5, is a concave and
rounded connection area 15, with a radius of curvature R1. Particularly
advantageous results have been obtained with particular types of covering
films
for values of the radius of curvature Rl that are greater than zero and less
than or
equal to 8 mm.
Preferably, a truncated cone shaped part 17 is produced in the variant of
bottle in
which the tapered part 5 has a form which is not a surface of revolution. The
truncated cone shaped part 17 is interposed between the tapered part 5 and the
neck 7, or between the tapered part and the area 15.
Figure 4 represents a top view of a bottle with the tapered part 5 with a
cross
section similar to the section of the body 2, as described above. The lower
limit of
the truncated cone shaped part 17 is indicated with the dashed line 16. It is
observed that it can also have a form similar to the cross section 'of the
tapered
part 5, to allow connection. In particular, said lower limit will have a
maximum
width D3 and a minimum width D4. Preferably, the following relation will
be,valid:
0.6 < (D2-D4)/(D1-D3) _< 1.
The truncated cone shaped part 17 is preferably inclined so that a plane
tangent
thereto forms with the axis I an angle a, ranging from 30 to 90 . Moreover,
with
coverings suitable to withstand shrinkages from 20% to 60% of the diameter,
values are preferred in which: 0.1 <_ (D1-D3)/D1 <_ 0.8 and 0.1 <_ (D2-D4)/D2
_< 0.8.
In the case in which the tapered part 5 is a surface of revolution, it is
possible that
D3=D4. This is also possible in the case in which a regular truncated cone
shaped
part, with a circumference as base, is present.
In an advantageous variant, the point of maximum inclination of the tapered
part 5
is immediately below the neck 7, or the area 15 if present, and is such that
the
CA 02569812 2006-12-07
WO 2005/123518 PCT/EP2005/052799
6
plane tangent in that point, as shown in Figure 3, forms an angle a with the
axis 1
ranging from 30 to 90 .
If the covering is to be applied up to the neck 7, it is preferable,
immediately below
this point of maximum inclination, for the tapered part 5 to have a
longitudinal
section with a radius of curvature R2 below 15 mm, to obtain, in a very
restricted
area below the neck 7, a variation in the profile of the wall of the bottle
from
concave to convex, through a point of inflection coinciding with said point of
maximum inclination, so as to essentially define an S-shape and therefore form
a
sort of "shoulder", which reduces the risk of the covering slipping, in
consideration
of the fact that there must be maximum shrinkage in this area.
With all the modalities described above the external form of the bottle is
improved
preventing the formation of creases and wrinkles in the covering in the area
below
the neck 7.
The bottle can be produced in any thermoplastic material considered suitable,
such as PVC, PET and the like, according to any known art, such as blow
moulding.
The invention also relates to a bottle covered with a heat-shrinkable film.
The
covering can include the body 2 and preferably all or part of the tapered part
5.
The tapered part 5, as described above, allows high-quality and uniform
adhesion
of the covering thereon, also for bottles the body of which is not circular,
solving
the problems indicated above. The presence of the truncated cone shaped part
17
and/or the "shoulder" formed by the accentuated curvature of radius R2 below
the
neck 7, moreover, has the advantage of providing fixing for the covering if it
extends up to the neck 7, preventing slipping or non-uniform tightness even in
this
critical area.
The covering can extend from the base 3 or in any case involve part of the
rounded connection area 18 which joins the base 3 to the body 2, providing
improved fixing, as is usually the case.
The covering can be made of a known thermoplastic material. For example, it
can
be constituted by a film comprising several layers, one of which is expanded:
plastic materials which can be used can be polyolefins, polystyrenes and the
like,
with additives and pigments to provide barrier properties against light and
atmospheric agents. Purely by way of example, a film with three co-extruded
CA 02569812 2006-12-07
WO 2005/123518 PCT/EP2005/052799
7
layers can be used, wherein the intermediate layer is expanded polystyrene and
the other layers are non-expanded polystyrene, the innermost of which is black
and the outermost of which is printable. The film can, for example, have a
thickness of around 120 rn, with the inner expanded layer having a thickness
of
around 100 m. The film can be wound around the bottle and glued or sealed by
two edges, to create a cylinder around the bottle, coaxial therewith for an
adequate height. It is shrunk in a known way, for example using hot air. It is
also
possible to start with a cylinder of film pre-formed by extrusion.
Those skilled in the art can easily make the choice of materials to employ to
produce the bottle and the covering, and also of the process conditions.
