TECHNICAL FIELD

The present invention relates to a seal for a container, and more

particularly an induction heat seal with a ring-shaped handle to facilitate removal of the seal from the container.

BACKGROUND OF THE INVENTION

There are currently various type of seals or closures which are designed to seal on the opening of a container. To open the container after sealing, the seal has to be either broken or peeled off. Such seals or closures are used in a wide variety of containers, e.g. bottles of foods, beverage, pharmaceuticals, and chemicals. Their primary function is to provide an element of protection to the products in the containers by separating the products from the external environment. In some cases, the seals also provide an indication if the contents have been tempered with. For comestible, the seals are frequently used to seal the contents to prevent the contamination of the food and maintain the freshness of the food. On the other hand, for chemical products, the seals are used to prevent the products from leaking and spilling. Induction heat seal is one of the most popular type of seals and is characterized for performing the sealing after undergoing the induction heat sealing process.

In 1960, The Palmer U.S. Pat. No. 2,937,418 is of some interest, as apparently being an early example of induction heat sealing of a seal to the neck of a bottle.

A seal suitable for induction heat sealing around the mouth of a container may contain a metal foil layer, function as generating heat during induction heating process. The metal foil layer has, on its underside, heat sealable layer for adhering to the bottle mouth, and on the upper side, may has a heat resistance layer to avoid damaging the cap. And, to open the container, the seal has to be either broken or peeled off.

Seals can be categorised into two types according to its bonding properties. First type is described as "permanent seal", which can bond firmly to the bottle neck, and it can't be peeled off by pulling the seal itself. Second type described as "peel-able seal", which provides just enough bonding strength to hold the seal and the bottle neck together, and can be peeled off from the bottle neck by pulling a tab, which extended sideways from the periphery of the seal, it either be folded down along the bottle neck or be folded up on top of the main portion of it. The former may have risk of causing the tab to bond to the neck of bottle, the latter may require extra effort to insert seal into the cap.

In 1979, the Fletcher et al U.S. Pat. No. 4,155,439 discusses in detail the production of a seal with a pull tab folded up on top of the main portion. In this patent, fully automatic machinery is introduced to form the seal and fit it to the container, not inserted into a cap.

1986, the Carr et al U.S. Pat. No 4,625,875 is primarily concerned with a temper-evident closure. Nevertheless, it does show a seal provided with a tab folded over on top of the main portion, and a paper board liner is placed between the seal and the cap.

Michael P. Galda et al U.S. Pat. No. 4,961 ,986 highlighted some problems that are encountered with this sort of technique. Firstly, the presence of the inwardly folded tab can affect the sealing by means of induction heating. Induction heating relies upon the generation of currents and hence heat in the foil. The presence of the tab affects the electrical properties locally, and can result in improper sealing. As discussed in an article by Bill Zito in August 1986 issue of Food and Drug Packaging, the current tends to follow the actual periphery of the tab. Also, the folded tab can stick to the inside of the cap, which then requires a paper board liner or silicone liner or the like.

Additionally, the induction sealing technique relies upon the fact that the foil closure is pressed against the neck of the container by the cap. With the folded tab present, there may not be even pressure applied to the seal, which again can result in imperfect sealing. Ideally, it should be of uniform thickness

throughout, and should be capable of uniform induction heating, so that it can be readily joined to the neck of a bottle by induction heating.

These problems were overcome by a seal with tap attached on top, which was apparently first introduced by Michael P. Galda et al U.S. Pat. No.

4,961,986 in year 1990. This seal includes a bottom sheet said sealing

membrane, e.g. aluminium foil with sealant layer underneath, and top sheet, half of which is adhered to the bottom sheet, the other half circle of the top sheet is free from adhesive, so to form a tab. To remove the seal, the tab is generally grasped between two fingers and is pulled laterally, and to make use of the bond provided by the adhesive between top sheet and the sealing membrane. As highlighted by Galda, if the tap is pull upward, or away from the free port ion, there may be a tendency for the top layer separate from the sealing membrane, depending upon the nature of the various materials used and bondi ng strength of the adhesive layer. To produce top tabbed seal, claimed by Galda et al U.S. Pat. No.

4,961 ,481 & 5,433,992, the adherent to bond the top layer and the sealing membrane, does not extend across the full width of the strip, it extends only along the left-hand side of the elongated strip, and leaves the extend along the right-hand side of the elongated strip without adherent. In practice, the elongated strip would be produced as part of a wider strip containing number of the elongated strips as shown in FIG 1 or suggested by other in U.S. Pat.

5,702,015, 6,866,926 Bl, 6,902,075 B2, 8,308,003 B2, 8,455,071 B2, to apply full width of adherent on the top layer, and feed in additional number of small strips e.g. PET films with a gap among each other, sandwiched by top layer and sealing membrane as shown in FIG 2. Once the elongated strip has been formed, each circular shape seal is die cut generally centrally from the elongated strip

In short, today there are two popular type of tabbed induction heat seal: side tabbed seal and top tabbed seal. As highlighted by Michael P. Galda et al U.S. Pat. No. 4,961,986, there are some problem encountered with side tabbed sea i.e. imperfect sealing. These problems were overcome by top tabbed seal first introduced by Michael P. Galda et al U.S. Pat. No. 4,961,986 in year 1990. However, the top tabbed seal has limited pulling angle and requires two fingers to pull it open.

Therefore, a need exists for an improved and reliable container seal, particularly having a rigid tab that allows the seal to be removed from the container easily.

SUMMARY OF THE INVENTION

The present invention provides a new type of seal. Most particularly, the present invention provides a closure seal with a peripheral ring-shaped tab that enables easy removal of the seal from the bottle.

In accordance with the preset invention, the sealing member is formed of a laminate comprising the following coextensive layers:

a) a plastic (PP, PE, PET, Nylon, etc) top layer;

b) a PE/PET adhesive layer

c) a PET plastic layer

d) a PET/foil layer

e) aluminum foil

f) a foil/heat seal adhesive layer

g) heat seal layer

PE film is adhered partially to the upper surface of the PET plastic layer and it will form a ring-shaped handle after die cutting. This handle assists in the removal of seal. The function of aluminum foil and PET film is to provide airtight protection to the content of the container. The function of the sealing medium, on the other hand, is to secure the entire sealing member onto the bottle after undergoing the induction heat sealing process. Adhesive holds all these layers together to become a composite material.

The invention further provides a method for manufacturing for this type of seal. Preferably comprising the method are the steps of, utilizing dry lamination process with gravure technique to bond the layers together and to apply partial bonding to the ring-shaped handle layer; inserting markings on the laminate during the dry lamination process, targeted printing by utilizing the markings mentioned; die-cutting the laminate into the design we want by implementing full-cut and partial cut.

The greatest advantage of the present invention is to provide a ring- shaped handle that enables easy-removal of the seal from the container while not disrupting the induction heat sealing process. The traditional inwardly folded tab can affect the sealing. On the other hand, the conventional top tabbed design has limited pulling angle and requires two fingers to pull it open. On top of that, end-users might have trouble removing the conventional top tabbed seal when their hands are wet because the conventional top tabbed design requires friction for it to work. The present invention can eliminate all the issues above. It has no inwardly folded tab to disturb the sealing process and the ring-shaped handle guarantees a convenient removal of the seal. The ring-shaped handle of the present invention enables the seal to be removed with one finger.

BRIEF DESCRIPTION OF DRAWING

The invention is further illustrated in the following drawing in which:

Fig 1 is a sectional view through the present invention

Fig 2 contains a 2D drawing showing how a fridge-tab seal is sealed on a container after the induction heat sealing process and a 3D drawing showing how the seal can be removed with only one finger.

Fig 3 is a detailed drawing of the present invention showing the glue area and the die cutting lie.

Fig 4 shows how the dry lamination process applies glue to the designated area with gravure block.

Fig 5 shows the mixing of filler into the adherents.

Fig 6 is a drawing of the die cutting mould used to produce the present invention.

Fig 7 illustrates how the marking sensor on the die cutting machine reads the markings to ensure accurate punching.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As shown in FIG 3, the present invention comprises a plastic top layer (I ) made from either PE, PP, PET and Nylon with a ring-shaped handle, a PET layer (2), an aluminum foil (3), a heat seal layer (4) and a combination of adhesive layer (5,6,7) to hold all the layers together to form a composite material. The composite material will be fully cut along a circle to form the seal and the top layer (1 ) will be cut partially to form the handle (10). The PET layer acts as a buffer layer to make sure that the aluminum foil (3) is 100% intact to protect the content of the container.

As shown in FIG 4, the seal will adhere to the mouth of the container (8) after the induction heat sealing process to protect the contents of the container as mentioned before. Upon removing the cap (9), we can see the seal with its peripheral ring-shaped handle (10). The ring-shaped handle (10) is not glued to the layer (2) below, enabling it to be lifted with only one finger. The ring- shaped handle is made from a thick, transparent and rigid plastic film to minimize the elongation of the handle when it is being pulled. Aside from that, the optimum pulling angle (11) for the present invention is much wider than the conventional top tabbed design. The present invention can be opened with an optimum pulling angle (1 1) from 10 degree to 135 degree due to the design of the handle (10). Conventional top tabbed seal, on the other hand, only allows the seal to be opened in very limited angle or risks breaking and delaminating the tab.

The detailed design of the present invention is showed in FIG 5. The design of the seal can be divided into two parts: the shape of the glue area (12) and the inner die cutting line (13). The glue area is a partial ring design with a parabolic curve ( 14) at the end. The shape of the parabolic curve is to ensure that the force is focused on a single point (15) to allow easy removal of the seal. On the other hand, the die cutting line (13) is to ensure that handle (10) is separated from the glue area (12) between the top layer (I) and the second layer (2), so that the handle can be lifted.

The manufacturing procedure of the present invention can be divided into

2 parts: dry lamination process and die cutting process. The dry lamination process uses a gravure block to bond all the layers together and uses a special gravure block (16) as shown in FIG 6 to apply glue to the designated area. To give a distinctive color to the seal and to produce markings (17) to assist with targeted punching later, colored filler is added to the adherent during the lamination process between top layer and the second layer as shown in FIG 7.

In the die cutting process, a die cutting mould as shown in FIG 6 is equipped with cutters of different height. The outer cutter (18) is slightly taller than inner cutter (19); to produce a full-cut on the composite liner to form the seal and to produce a half-cut along the inner die cutting line (13) to form the handle.

The markings (17) that have been created in the dry lamination process is very important during the die cutting process. As shown in FIG 7, the marking sensor (20) on the die cutting machine will read the colored markings (17) and guide the machine to cut at the correct position.