Plastic Lid With Integrally Connected Film And Container Comprising Said Lid

Abstract

The invention concerns an injection moulded packaging (1) comprising a plastic material container (2), such as a polypropylene container, and a lid (3), said lid (3) comprising a first portion (10) in the form of a plastic material film and an injection moulded plastic material second portion (20), said second portion (20) being adapted to be heat sealed to a rim (6) of said container (2) by heating the plastic material (30) of said second portion (20) in a peripheral edge region (4) of said lid (3) to a heat sealing temperature T, said first (10) and second (20) portions being integrally connected, such as through an IML-process, said first portion (10) defining an upper surface (11) of said lid (3) facing away from said container (2). The first portion (10) covers said second portion (20) at least along said peripheral edge region (4), said first portion (10) including along said peripheral edge region (4) a layer (12) of a plastic material which is dimensionally stable at said heat sealing temperature T.

Description

The present invention relates to a packaging comprising an injection moulded container and a lid that can be sealed to the container. An example of such a packaging is disclosed in SE patent 512 612 and EP patent 2 194 002.

In such packagings the lid is made with a sealing zone for joining directly with the container. Thereby, a solid connection and sealing between the lid and the container may be obtained. A flap on the lid as shown in WO patent application 2009156401 may ensure that the lid is easy to remove from the container.

The object of the present invention is to provide a packaging having improved properties by reducing the risk that local defects in the seal may occur, thereby reducing the risk that contaminants may enter the sealed container.

In view of this object, the lid of the present invention in an integral manner includes an upper lid portion in the form of a plastic material film that covers a lower lid portion at least along the lid peripheral edge. The plastic material film includes at least along this peripheral edge region a layer of a plastic material which is dimensionally stable at the heat sealing temperature at which the material of the second portion is fused to the container.

In this way, the risk is prevented or reduced that the material of the second portion is displaced away from the sealing area during the sealing operation which may lead to formation of spots along the container rim where contaminants may enter the packaging and reduce the shelf-life of any product contained therein.

The invention will now be explained in more detail below by reference to an embodiment.

FIG. 1 is a perspective view of a packaging according to the invention, seen from above,

FIGS. 2a and 2b are schematic cross-sectional views of a prior art packaging, when the lid is being heat sealed to the container,

FIG. 3 is a schematic partial cross-sectional view of the packaging in FIG. 1, and

FIGS. 4a and 4b are partial schematic cross-sectional views of the exemplary embodiment of the invention, shown when the lid is being heat sealed to the container.

FIG. 1 shows a plastic material packaging 1 according to the present invention. The packaging 1 comprises a container 2 and a lid 3 that is heat sealed to the container 1, numerals 5 and 11 designating a gripping tab for removing the lid 3 and the upper surface of the lid 3, respectively. The container 2 may have any suitable form, such as round, oval, square or rectangular, and its cross-section may be tapering in downward direction

Packagings 1 of this general type are well-known, and may be used for storing various products, such as, for instance, soft dairy products or the like. The container 2 is normally injection moulded and may be provided with a label fused to the outside container side wall through an In-Mould Labelling (IML) process, such as the one disclosed in EP patent 481 090.

When heat sealing such a lid to a container a problem is sometimes encountered in that locally no seal is established. This is illustrated in FIGS. 2a and 2b where reference numeral 9 indicates a heating/welding bar applied at an elevated temperature T to the lid 3′ so as to fuse the lid 3′ and container 2′ together along a peripheral edge region 4′ of the lid 3′ along the rim 6′ of the container. On applying the heated welding bar 9 against the lid 3′ the plastics material of the lid 3′ may locally be displaced away such that no part of the lid 3′ is sealed to the rim 6′ in spots along the rim 6′, as shown in FIG. 2b. Hence, there is a potential risk that air or contaminants may enter the packaging 1′, thus reducing the shelf-life of any product contained therein. FIGS. 2a and 2b show the lid 3′ as including a label 10′ defining a first portion of the lid 3′ and fused to the middle area of a second, lower portion 20′ of the lid 3, such as through the IML-process disclosed in FR patent 2 700 493.

With the aim of solving the above problem, according to the invention the lid 3 is formed as shown in the enlarged view of FIG. 3 where a first portion 10 of the lid 3 provided originally in the form of a film is integral with and covers a second, lower portion 20 of the lid 3, at least along the peripheral edge region 4 where the lower portion 20 of the lid 3 is fused to the container 2 rim 6. The first portion 10 of the lid includes at least in and along the peripheral edge region 4 a dimensionally stable layer 12 of a plastic material which is selected such that this layer remains dimensionally stable at the heat sealing temperature T of the heating/welding bar 9.

When sealing the lid 3 to the container 2 the temperature T of the heating/welding bar 9 is selected to be between the melting temperature T₁ of the plastic material of the second portion 20 and the melting point T₂ of the layer 12. By way of example, the material of the second portion 20 may be PP (Polypropylene) which has a melting point T₁ of about 166° C. while the dimensionally stable layer 12 may be of PET (polyethylene terephthalate) which has a melting point T₂ higher than 250° C. The temperature T of the heating/welding bar 9 may be selected to be around 200° C.

When selecting the temperature T as described above the layer 12 will remain dimensionally stable during the heat sealing and thus define a stable base or backing for the material of the second portion 20 in the aforementioned edge region 4. It has been found that this prevents or reduces the risk that the material of the second portion 20 is displaced away. This effect is illustrated in FIG. 4b; the plastic material 30 of the second portion 20 along the peripheral edge 4 is heated to its melting point such that the lid 3 is fused to the rim 6 of the container 2. With the dimensionally stable layer 12 remaining as a backing for the material 30 to adhere to the risk that the plastic material 30 is displaced away is significantly reduced.

The second portion 20 of the lid may either define the lower surface of the lid, or the second portion may be an annular or grid-like structure as shown in FIG. 5 of FR patent 2 700 493 whereby the first portion defines the lower surface of the lid 3.

The first portion 10 of the lid may additionally include a barrier layer 14 for controlling the air permeability of the lid 3 and preferably being made of a material selected from the group of SiOx and PVDc. The dimensionally stable layer 12 may conveniently be a polyamide or PET-layer which fulfills the selection criteria when the second portion 20 plastics material is polypropylene PP. Moreover, the first portion 10 may include a layer 16, such as a polypropylene layer, of a material similar or identical to that of the second portion 20 and which is fused to the second portion 20 when manufacturing the lid, such as in an IML-process, where the first portion 10 is inserted into the injection mould following which plastics material is injected, thus moulding the second portion 20 and forming the integral connection between the first and second portions. Preferably, the second portion 20 is made of polypropylene, optionally a polypropylene material containing additives for controlling the strength of the heal seal, as discussed in WO patent application 2007 071252. The lid 3 may include along the peripheral edge region 4 a recess 16 for receiving the welding tool 9; to define this recess the second portion 20 may have a reduced thickness along the peripheral region 4.

The film-like first portion 10 shown in the enlarged view of FIG. 3 may be provided as a continuous web which is cut into the desired shape and inserted into the mould in an IML-process.

Claims

1. A packaging (1) comprising an injection moulded plastic material container (2), such as a polypropylene container, and a lid (3), said lid (3) comprising:

a first portion (10) in the form of a plastic material film integrally connected with an injection moulded second portion (20) of a plastic material having a melting point T1,

said second portion (20) being adapted to be heat sealed to a rim (6) of said container (2) by heating the plastic material (30) of said second portion (20) in a peripheral edge region (4) of said lid (3) to a heat sealing temperature T,

said first portion (10) preferably defining an upper surface (11) of said lid (3) facing away from said container (2),

wherein said first portion (10) covers said second portion (20) at least along said peripheral edge region (4),

said first portion (10) including along said peripheral edge region (4) a layer (12) of a plastic material which has a melting point T2 higher than said melting point T1 of the plastics material of said second portion (20).

2. The packaging of claim 1, wherein said second portion (20) defines the surface of said lid (3) that faces the interior of said container (2), said first portion (10) covering all or essentially all of said second portion (20).

3. The packaging of claim 1, wherein said second portion (20) comprises an annular body, said first portion (10) spanning across said annular body and defining also a surface of said lid that faces the interior of said container (2).

4. The packaging of claim 1, wherein said first portion (10) carries indicia relating to the contents of said container (2), said indicia being visible when said lid (3) is sealed to said container (2).

5. The packaging according to claim 1, wherein said indicia is printed on said first portion (10) prior to connecting said first portion (10) with said second portion (20).

6. The packaging according to claim 1, wherein said second portion (20) and said container (2) include means (100) mechanically engaging each other to secure said lid (3) to said container (2).

7. The packaging according to claim 1, wherein said layer (12) comprises a polyamide- or PET material layer.

8. The packaging according to claim 1, wherein said first portion (10) includes a barrier layer (14) for controlling air permeability of said lid (3), said barrier layer (14) preferably being made of a material selected from the group of SiOx and PVDc.

9. The packaging according to claim 1, wherein said first portion (10) includes a further layer (16), such as a polypropylene material layer, fused to said second portion (20) to define said integral connection.

10. The packaging according to claim 1, wherein said second portion (20) comprises polypropylene, optionally a polypropylene material containing additives for controlling the strength of said heat seal.

11. The packaging according to claim 1, wherein said lid (3) includes along said peripheral edge region (4) a recess (16) such that said second portion (20) has a reduced thickness along said peripheral region (4).

12. A lid for a plastic material container (2), said lid (3) comprising:

a first portion (10) in the form of a plastic material film and an injection moulded plastic material second portion (20),

said second portion (20) being adapted to be heat sealed to a rim (6) of said container (2) by heating the plastic material of said second portion (20) in a peripheral edge region (4) of said lid (3) to a heat sealing temperature T, said first (10) and second (20) portions being fused together, such as through an IML-process,

said first portion (10) defining an upper surface (11) of said lid (3) adapted to face away from said container (2),

wherein said first portion (10) covers said second portion (20) at least along said peripheral edge region (4),

said first portion (10) including along said peripheral edge region (4) a layer (12) of a plastic material, such as polyamide or PET,

which remains dimensionally stable at the temperature T where said plastic material of said second portion (20) is suitable for said heat sealing.

13. The lid of claim 12, wherein said second portion (20) plastic material comprises polypropylene PP.

14. A lid for a plastic material container (2), said lid (3) comprising:

a first portion (10) in the form of a plastic material film and an injection moulded plastic material second portion (20), said second portion (20) being adapted to be heat sealed to a rim (6) of said container (2) by heating the plastic material of said second portion (20) in a peripheral edge region (4) of said lid (3) to a heat sealing temperature T, said first (10) and second (20) portions being fused together, such as through an IML-process, said first portion (10) defining an upper surface (11) of said lid (3) adapted to face away from said container (2), wherein said first portion (10) covers said second portion (20) at least along said peripheral edge region (4), said first portion (10) including along said peripheral edge region (4) a layer (12) of polyamide or PET, and said second portion (20) plastic material and said container plastic material being polypropylene PP.

15. A method of heat sealing the packaging of claim 1, wherein said heat sealing temperature is selected to be between said temperature T1 and T2.