[0001] The invention relates to a process for packaging margarine and similar products which
have the tendency to adhere to the packaging material, as a result of which opening
of the packages is made more difficult.
[0002] In German Utility Model 79 02 913 it is proposed to decrease considerably the adherence
of pasty products to the closure part by providing the closure part, on a side turned
towards the products, with a plurality of small, separate cavities. The disadvantage
of this solution, however, is that the cavities on the inner side, obtained for example
by embossing, stand out more or less clearly on the outer side of the closure part
and that with relatively thin packaging material satisfactory embossing often cannot
be achieved.
[0003] The aim of the invention is therefore to decrease the adherence of the pasty products
to the packaging material, also in the case of closure parts which are smooth on their
inner side, so that these packages can be opened easily.
[0004] It has now been found that, at least with certain packages where the surface of the
product is essentially smooth and relatively firm, the cavities which reduce adherence
and in which small air cushions are enclosed can also be made in the surface of the
product.
[0005] In order to solve the above-mentioned problem, when margarine and similar products
are being packaged, before the closure parts are laid against the surface of the portion
placed in the container, provision is made for a pattern of small cavities being made
in this surface and then a closure part with a smooth inner side is pressed against
the edges of the surface surrounding the cavities.
[0006] The cavities have an open area of 0.5 mm
2 to 20 mm
2, preferably 2 2 of 2 mm
2 to 6.5 mm
2, measured approximately in the plane of the surrounding edges, and a depth of 0.4
to 2.5 mm. They are made in the surface of the product, before the lid is put on,
by embossing or by jets of gas, e.g. air, directed against the surface. By placing
the lid on the edges of the cavities, each of the cavities filled with air or inert
gas is sealed off from the neighbouring cavities. When this is done a monitored small
amount of air or inert gas is enclosed in each cavity in the surface of the product.
In the closed packages the cavities are not connected with each other. On the contrary,
each cavity contains a small air cushion with a very slight excess pressure caused
by pressing of the closure part against the edges of the cavities. If the cavities
are obtained by blowing air against the surface, in that case they form little craters
the edges of which are not entirely regular but, as a result of the closure part being
pressed down, are brought into a plane with those of the neighbouring cavities, each
cavity then being sealed off. Through the use of an embossing tool, cavities of any
given cross-section can be obtained, e.g. in the form of truncated pyramids.
[0007] If necessary, before the cavities are made, the product can be given a substantially
smooth surface, for example by a press-on tool, and/or e.g. its surface be solidified
to such an extent by cooling that the cavities can be made and for the greater part
will last.
[0008] The process is particularly suitable for the packaging of pre-formed portions of
margarine of somewhat firmer consistency in erected folding boxes of cardboard material
which are to be closed with a lid. However, it can also be applied with beakers or
trays which are closed with a plastic lid having a smooth inner side. Finally, the
process can also be applied to one or more surfaces of a pre-formed portion which
is enclosed by a wrapper.
[0009] The invention relates to the apparatus for carrying out the process, which is distinguished
from the known apparatuses e.g. for introducing the product into the package and for
closing the package in that it has in addition a device for making the small cavities
in the surface of the product, against which a closure part is pressed down.
[0010] This device for making the cavities can be an appropriately profiled die. A hollow
die with a great number of nozzle-like openings is preferred. Jets of air or gas are
blown intermittently against the surface of the product. The die can be heatable on
its side that is turned towards the product and can be provided with a special coating
which, for example, hinders adherence of the product to the die. The use of heated
gas for the blowing is possible, but local melting of the product by the jets of air
should be avoided. Instead of a die, an appropriately structured roller can be used,
under which the unclosed, filled package is transported continuously.
[0011] Embodimentsof the invention will now be described with reference to the attached
schematic drawings.
Fig. 1 shows cross-section of a filled, unclosed package and a hollow die with openings
for blowing through the air;
Fig. 2 is as Fig. 1, but while air is being blown through;
Fig. 3 is a cross-section of the closed package;
Fig. 4 to 6 show magnified sections of a package before and after the cavities have
been made and after the lid has been pressed on;
Fig. 7 shows a cross-section of an embossing die.
[0012] A portion of margarine 1 is placed in a folding box 2, which is to be closed by a
lid 3, the lid 3 being pressed down against the surface 4 of the portion and partly
overlapping the front side 5 of the folding box 2. Such a package is difficult to
open if adherence of the surface 4 and the lid 3 is not reduced.
[0013] A hollow die 11 with a plurality of small, nozzle-like openings 12 in the side turned
towards the surface 4 of the margarine is moved towards the filled, unclosed package
(Fig. 1). When the die 11 is almost touching the suface 4, air or a suitable gas is
intermittently introduced via a gas supply, which air or gas spreads itself in the
hollow space 14 of the die 11 over the openings 12 and creates a small, crater-like
cavity 6 under each opening 12 (Fig. 2). Thereafter the package is closed, with the
inner side of the lid 3 lying on the surface 4, and, as a result of the lid 3 being
pressed against the surface 4 on to the edges 7 of the cavities 6, in each cavity
6 an air cushion of a size determined by the volume of the cavity 6 is enclosed, which
is isolated with respect to the neighbouring air cushions (Fig. 3).
[0014] Fig. 4 shows a cross-section of a part of a package with enclosed product of which
the surface 4 is substantially smooth. Fig. 5 shows the cavities 6 made by blowing,
which have edges 7 pressed upwards to some extent in a surface 4. In Fig. 6 the lid
has been put on and pressed down, the edges 7 being brought into a plane and the separate
cavities being sealed off with respect to each other.
[0015] Fig. 7 shows a die 21 which is profiled on its under-side with a plurality of pins
or similar projections which have the form of a pyramid or a truncated cone and, for
example, are staggered. The die 21 is pressed partly into a surface of a product and
hereby embosses a pattern of many tiny cups or suchlike, corresponding to its profiling,
which, however, are likewise independent of each other.
[0016] The sum of all cross-sectional areas of the cavities, measured in the plane of the
surface of the product or of the edges surrounding the cavities, must be at least
approximately 10% of the total surface area of the product. The maximum of the sum
of the cross-sectional areas depends on the size of the separate cavities and on the
total surface area as well as on the firmness of the product.
1. A process for packaging margarine and similar products in containers which are
closed by closure parts which are in contact with the product, characterized in that,
before the closure parts are placed on the surface of the portion inserted in the
container, a pattern of small cavities is made in this surface and subsequently a
closure part with a smooth inner side is pressed down against the edges of the surface
surrounding the cavities.
2. A process according to claim 1, characterized in that 2 2 cavities with an open
area of 0.5 mm2 to 20 mm2, preferably of 2 mm2 to 6.5 mm2, measured approximately in the plane of the surrounding edges, and a depth of 0.4
to 2.5 mm are made in the surface of the product before the lid is put on.
3. A process according to claim 1 or 2, characterized in that each cavity is made
by blowing a jet of air or gas against the surface of the product.
4. A process according to claim 1 or 2, characterized in that the cavities are made
by embossing.
5. A process according to any one of the claims 1 to 4, characterized in that a monitored
amount of air or an inert gas is enclosed in the cavities in the surface of the product
by putting on the lid.
6. A process according to any one of the claims 1 to 5, characterized in that by putting
the lid on the edges of the cavities each of the cavities filled with air or an inert
gas is sealed off from the neighbouring cavities.
7. An apparatus for carrying out the process according to any one of the claims 1
to 6 for packaging margarine and similar products, consisting of devices for introducing
the product into the package and other devices for closing the package, in which the
closure parts are pressed down against the surface of the product, characterized in
that it has a device (11, 21) for making small cavities (6) in the surface (4) of
the product, against which a closure part (3) is pressed down.
8. An apparatus according to claim 7, characterized in that the device for making
the cavities (6) is a hollow die (11) with a plurality of nozzle-like openings (12)
for intermittent blowing of jets of air or gas against the surface (4) of the product.
9. An apparatus according to claim 7, characterized in that the device for making
the cavities (6) is a die (21) that is provided with a plurality of profilings (22)
corresponding with the cavities to be made.
10. An apparatus according to claim 8 or 9, characterized in that the die (11,21)
can be heated on its side that is turned towards the product.
11, An apparatus according to claim 8 or 9, characterized in that the die (11,21)
is provided with an anti-adhesive coating on its side that is turned towards the product.