Title of Invention

"A PLASTIC CLOSURE CAP"

Abstract

The present invention relates to a closure cap for containers. More particularly, the present invention relates to a closure cap for screw top containers such as polyethylene terephthalate/glass/metal bottles and containers containing beverages that require to be water and air proof during transportation and storage, such as aerated beverages, soft drinks, medicines, oils, various industrial fluids, alcoholic beverages and the like. The present invention also relates to liner elements for closure caps for hermetically sealing bottles, jars and other containers which use removable closure members.

Full Text

CLOSURE CAP FOR CONTAINERS FIELD OF THE INVENTION The present invention relates to a closure cap for containers. More particularly, the present invention relates to a closure cap for screw top containers such as polyethylene terephthalate/glass/metal bottles and containers containing beverages that require to be water and air proof during transportation and storage, such as aerated beverages, soft drinks, medicines, oils, various industrial fluids, alcoholic beverages and the like. The present invention also relates to liner elements for closure caps for hermetically sealing bottles, jars and other containers which use removable closure members. BACKGROUND OF THE INVENTION It is known in the art to use closure caps with a protective sealing liner element provided therein in the packaging of various comestibles and beverages in bottles and jars. Such interior liners cover the interior end surface of the closure cap and when the cap is tightly secured to the dispensing end of the container, the liners press against and confirm to the surface configuration of the dispensing end of the container. This is done in order to hermetically seal the container and in order to maintain the contents of the container in a pristine condition till actual consumption or use. Typically, such closure caps are manufactured from metallic materials such as aluminum, tin or chrome plated steel or from plastics. A tremendous interest has also been shown in the art, both by industry and by various regulatory authorities such as the US Food and Drug Administration in the use of alternative hermetically sealable liner materials which are compatible with packaged products intended for human consumption. A reason for such interest is that development of alternate lining materials or methods will result in reduced material costs. US Patent 4,151,924 (1979) discloses an improved liner element for a closure cap which is bonded to the interior end surface of the cap. The liner element has a laminated structure comprising a backing layer or cushion layer of surface-sorbent material, such as fabric, a relatively thin sheet of paper or comparable surface-sorbent cellulosic or paper-like membrane or substrate, having an inner face which is surface-bonded to the interior end surface of the closure and has an outer face which is surface-bonded to a barrier layer of pliant polymeric material. The barrier layer of polymeric material is apparently selected in order to be impermeable to water vapor and gaseous transmission such that it is of use for closure caps used for containers for packaging comestible products and carbonated or non-carbonated, alcoholic and non-alcoholic beverages. It is disclosed therein that the barrier layer (the liner) should be inert with respect to the container's contents to avoid impairment or alteration of the color, flavor or quality characteristics of the contents of the container. The liner element and the closure cap are manufactured independently and then heat bonded. The focus in this patent is on the selection of the liner material so as to reduce material cost US Patent 4,984,703 discloses a closure cap that has a plastic base and a peripheral skirt and threads for securing the cap to the container and a sealing liner compression moulded apparently in situ to the interior of the cap base. US Patent 4,057,159 discloses a vapor seal safety cap and container with such cap. The container of this patent comprises a cylindrical plastic body molded in one piece and has circumferentially spaced, radially extending notched projections on the upper end thereof. The closure cap apparently comprises a one-piece plastic body having a top panel and an annular depending skirt with circumferentially spaced lugs extending radially inwardly for engagement with the notches. An annular integral rim or abutment is provided on the annular surface of the top panel of the closure and depends downwardly therefrom. A two-piece, vapor-seal liner is interposed between the annular abutment and the lugs for engagement with the upper end of the container. The two-piece liner includes a resilient disk which serves as a spring between the closure and container and a deformable disk positioned beneath the resilient disk which is pressed into sealing engagement with the upper rim of the container to provide a vapor-tight seal between the closure and container. US Patent 3,478,911 discloses a vapor seal in a closure cap. However, such sealing liners are not sufficiently resilient or deformable to tolerate repeated opening and closing of the container and therefore the effectiveness thereof reduces with continued use. US Patent 3,929,246 discloses a moulded plastic closure cap unit comprising of an upper closure cap, a lower integrally molded sealing ring with an inner diameter equal to the diameter of the closure cap and an intermediate shear zone with axially extending ribs which integrally connect the closure cap the sealing ring. US Patent 4,640,428 discloses a plastic closure system intended for use with bottles or containers which contain liquids under pressure such as carbonated soft drinks. The closure system of this patent comprises a liner with a high gas barrier material in a relatively thin layer positioned over the end of the container neck. According to this disclosure, the liner is designed to increase sealing forces applied thereto due to the internal pressure acting against the liner. US Patent 4,658,976 discloses a plastic closure having a plastic liner disposed therein and adapted to assemble with a container and provide a side and a top seal between the closure and the container wall adjacent tot he container mouth. The closure comprises a plastic cap with an annular edge near the junction of the top wall and the skirt. The top seal between the closure and the rim of the wall surrounding the bottle mouth is effected by compressing a portion of the liner therebetween. US Patent 4,721,221 discloses a moulded plastic closure for a beverage container. The closure comprises a shell with a top panel and a depending skirt, the shell being moulded in one piece from a thermoplastic material. The liner is formed in situ within the closure by compression molding from a compression moldable soft rubbery material. US Patent 5,289,932 discloses a cap with a plastic interior liner which are bonded together by melting them to one another. It is claimed therein that such a bond is durable and resistant to solvent vaporizing action. All the prior art methods described above have attempted to solve the problems of rapid deformation of the inner liner and therefore the sealing effect, high liner material wastage and costs, by using either alternate materials. Such prior art methods normally comprise molding the outshell of the cap by injection molding/compression molding followed by a second step of injection molding or compression molding the inner liner. The inner liner is then placed inside the outshell. Alternative methods comprise first injection molding the outshell, and then compression molding the inner liner into the outshell. Alternatively, the outshell is compression molded followed by compression molding the inner liner into the outshell. Such prior art liners are generally disc shaped and circular. The resultant plastic closure cap produced by each of the above methods comprises an outshell and a circular disc shaped inner sealing liner. A significant problem in prior art closures is that construction of such closures provides no means for preventing loss of the contents of the container due to evaporation or leakage. For example, where the contents comprise volatile fluids such as industrial solvents or carbonated beverages or various gases, it is important that the loss of contents due to evaporation during storage be minimi2ed. Such evaporation losses typically occur during storage either pre-use or post-use. Another problem with prior art closures is that moisture or vapor or air can penetrate through to the contents of the container. As is evident, in the case of aerated or carbonated beverages and even in the case of medicines, exposure to air or moisture can be destructive of the nature and quality of the contents of the containers. Another significant problem of the prior art methods and closure caps manufactured thereby is that of significant energy costs involved in two separate molding steps - that of the closure cap, and of the inner liner. This also results in a significant amount of material wastage at the center of the closure due to the use of disc shaped liners. It is therefore important to provide a closure cap with an integral inner liner which is preferably annular, and a method therefor which can overcome the above disadvantages. OBJECTS OF THE INVENTION The main object of the invention is to provide an annular liner for a plastic closure cap for containers. The main object of the invention is to provide a plastic closure cap for a container which comprises of an annular inner liner with an integral connection therebetween. It is another object of the invention to provide a plastic closure cap with an integral annular inner liner for a container that provides a sealing engagement with the dispensing end of the container and is substantially vapor and water proof. It is another object of the invention to provide a method for the manufacture of an annular liner for a plastic closure cap for containers, wherein the annular liner is integral with the closure cap, thereby avoiding material wastage at the center of the liner. It is yet another object of the invention to provide a method for the manufacture of a plastic closure cap for a container which comprises of an annular inner liner with an integral connection therebetween and also results in energy savings. It is another object of the invention to provide a method for the manufacture of a plastic closure cap with an integral annular inner liner for a container that provides a sealing engagement with the dispensing end of the container and is substantially vapor and water proof. It is yet another object of the invention to provide a method for the manufacture of a plastic closure cap with an integral annular inner liner by a one step method which significantly reduces both energy costs and material wastage. SUMMARY OF THE INVENTION The present invention accordingly provides a plastic closure cap comprising an outshell, said outshell being provided with an upper surface, sidewalls extending downwardly from the outer edges of the upper surface, the upper surface having an exterior portion and an interior portion, a substantially annular inner liner being provided integrally connected thereto on the interior portion of the upper surface. In one embodiment of the invention, the upper surface of the outshell is substantially circular in shape, and the sidewall comprises of a cylindrical single piece extending downwardly from the outer edges of the upper surface, with the annular inner liner being integrally connected to the inner portion of the upper surface and to the sidewall at the junction of the sidewall to the upper surface. In another embodiment of the invention, the annular inner liner is comprises of a tvvo concentric raised walls with a groove being formed therebetween so as to provide a siting for the dispensing end of the container. In yet another embodiment of the invention, the plastic closure cap comprises a groove formed between the outer periphery of the annular inner liner and the inner surface of the sidewalls so as to provide a siting for the outer edge of the dispensing end of the container. The present invention also provides a single step method for the manufacture of a plastic closure cap with an integral annular inner sealing liner comprising co-molding the annular inner liner and the outshell in situ in a single mold. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS Figure 1 is a schematic representation of an exploded view of the container neck, sealing liner ring and closure cap. Figure 2a is a schematic representation of the closure cap of the invention. Figure 2b is a schematic representation of the closure cap of the invention showing the crosssectional view thereof with the outshell and the liner resting on the container neck. Figure 2c is another schematic representation of the cross sectional view of the closure cap of the invention. . Figure 3 is a schematic representation of a sectional view of the closure cap of the invention. Figure 4 is a sectional view of the liner profile used in the invention. DETAILED DESCRIPTION OF THE INVENTION The present invention provides a plastic closure cap which comprises an outshell having an integrally connected annular liner on the interior thereto. The outshell has an upper surface with sidewalls that extend downwardly from the outer edges thereof. The upper surface has an exterior exposed portion and an interior portion. The liner is integrally co-injected to be connected to the interior portion of the upper surface. The upper surface of the outshell is substantially circular in shape, and the sidewall can comprise of a cylindrical single piece extending downwardly from the outer edges of the upper surface. The annular inner liner is then integrally connected to the inner portion of the upper surface and to the sidewall at the junction of the sidewall to the upper surface. The annular inner liner is comprises of a two concentric raised walls with a groove being formed therebetween so as to provide a siting for the dispensing end of the container. The plastic closure cap can also comprise a groove formed between the outer periphery of the annular inner liner and the inner surface of the sidewalls so as to provide a siting for the outer edge of the dispensing end of the container. The closure cap of the invention is manufactured by a single step injection molding method whereby both the annular inner liner and the closure outshell are molded together in a single mold. The present invention will now be described with reference to the accompanying drawings which are illustrative and should not be construed as limiting the scope of the invention in any manner. Figure 1 is an exploded schematic view of the closure of the invention as it would finally be used on a container. In Figure 1, the container depicted is a bottle such as a PET botde. While the liner (2) is depicted apart from the closure outshell (1), it must be emphasized that in actual use they are integral. The liner comprises a deformable and resilient material which is capable of adapting to the surface of the dispensing end (4) of the container (3). The liner comprises of two outer walls (5,6) and is substantially annular in shape. The two outer walls (5,6) and the groove (7) disposed therebetween receive the dispensing end (4) of the container (3) and form a hermetic seal during use. The resilience and deformability of the material of which the liner itself is made ensures that when the container is opened, i.e. when the closure cap is removed from the container, the liner outer walls move to a rest position and when the container is resealed, move back to a hermetic seal position. The closure cap itself comprises of an upper surface (8) and an inner surface (not shown) and a side wall (9) extending downwardly from the peripheral edges of the upper surface. Conventional screw thread closing means can be provided at the end of the sidewalls away from the upper surface to ensure a conventional sealing of the container by cooperating with the corresponding threads on the container. Figure 2a is a schematic representation of the closure cap of the invention, the upper surface (21) has a cylindrical sidewall (22) extending downwardly therefrom. The annular liner (not shown) is disposed of inside the cap. A set of bridges (24) is provided extending downwardly from the farther edges of the sidewall in order to enable heat welding of a further annular layer (not shown) to form a smooth closure with the container away from the dispensing end. This further annular layer (shown in Figure 2b and 2c as 26 and 26') serve to form a safety seal. The purpose of the safety seal is to indicate whether the container when sold is in a perfect sealed condition or has been opened prior to sale. Figure 2b is a cross sectional view of the closure cap of the invention in actual use on a container, the outshell and the liner resting on the container neck. Figure 2c is a cross sectional view of the closure cap of the invention when not sealing a container. From Figures 2b and 2c, which depict various cross sectional view of the closure cap of the invention, the integral connection between the annular inner liner (31, 31' respectively) within outshell (30, 30' respectively) can be seen. Figure 3 is a schematic representation of a sectional view of the closure cap of the invention. The annular liner (33) is provided connected integrally to the inner surface (34) of the outshell (35). In the embodiment depicted, the annular inner liner comprises two walls (36,37) extending downwardly and a groove (38) disposed therebetween to form a siting for the dispensing end of the container. The sidewalls (39) are provided with thread receiving means to correspond and cooperate with the respective threads provided on a container (not shown). While the annular liner itself can form the groove to site the dispensing end of the container, the groove can also be formed between the annular liner and the interior portion of the side walls, In such a case, the annular ring preferably comprises a single piece annular ring without the two walls extending downwardly as discussed above. Figure 4 is a sectional view of the liner profile used in the invention. The annular liner (41) is provided connected integrally to the inner surface (42) of the outshell (40). In the embodiment depicted, the annular inner liner comprises two walls (43, 44) extending downwardly and a groove (45) disposed therebetween to form a siting for the dispensing end of the container. The sidewalls (46) are provided with thread receiving means to correspond and cooperate with the respective threads provided on a container (not shown). In the specific embodiment depicted in Figure 4, the intended use is for water bottles and carbonated soft drinks. The closure itself is preferably made of materials such as polyolefins such as low density polyethylene(LDPE), high density polyethylene (HDPE), polyethylene, polypropylene, polystyrene, styrene based polymers, thermoplastic elastomers, thermoplastic vulcanizates. The annular inner liner is preferably made of polyolefins such as polyethylene, low density polyethylene, polyvinyl chloride, thermoplastic elastomers and thermoplastic vulcanizates. The closure of the invention is made by a co-molding process which comprises either injection molding the closure with injection molding of the annular inner liner, or compression molding of the closure with compression molding of the annular inner liner or by injection molding of the closure with compression molding of the annular inner liner. The molding equipment itself is conventional. A preferred method for the manufacture of the closure cap is given below. The closure body is injection molded by horizontal injection with a screw extruder with a L/D screw ratio of about 32 in four progressively increasing temperature zones preferably ranging from 160 - 240°C. The injection pressure can range from 700 — 1800 kg/cm2. The annular inner liner is injection molded by vertical molding over three temperature zones ranging from a temperature of 120 - 185°C at a L/D of the screw of about 28 and at an injection pressure of 600 —1000 kg/cm2. The following example is illustrative of one embodiment of the method of the invention used to prepare the closure and integral annular liner of the invention Example Polypropylene was injection molded at an injection pressure of 1200 kg/cm2 with a screw L/D of 32. The extrudate went through four temperature zones of 180°C, 200°C, 210°C and 220°C respectively. At the same time, polyethylene was co-injected by injection molding with a screw L/D of about 28 and went through three temperature zones of 120°C, 140°C and 165°C respectively. The injection pressure was maintained at 800 kg/cm2. The mold used was conventional for the closure and was adapted to the extent of enabling co-injection of closure and circular annular liner. It must be understood that what is described above is only illustrative of the invention. Modifications are possible without departing from the scope and spirit thereof. WE CLAIM: 1. A plastic closure cap comprising an outshell, said outshell being provided with an upper surface, sidewalls extending downwardly from the outer edges of the upper surface, the upper surface having an exterior portion and an interior portion, a substantially annular inner liner being provided integrally connected thereto on the interior portion of the upper surface. 2. A cap as claimed in claim 1 wherein the upper surface of the outshell is substantially circular in shape, and the sidewall comprises of a cylindrical single piece extending downwardly from the outer edges of the upper surface, with the annular inner liner being integrally connected to the inner portion of the upper surface and to the sidewall at the junction of the sidewall to the upper surface. 3. A cap as claimed in claim 1 wherein the annular inner liner is comprises of a two concentric raised walls with a groove being formed therebetween so as to provide a siting for the dispensing end of the container. 4. A cap as claimed in claim 1 wherein the plastic closure cap comprises a groove formed between the outer periphery of the annular inner liner and the inner surface of the sidewalls so as to provide a siting for the outer edge of the dispensing end of the container. 5. A cap as claimed in claim 1 wherein the annular inner liner comprises a single lip which is sitable on the outer edge of the dispensing end of the container. 6. A single step method for the manufacture of a plastic closure cap with an integral inner sealing liner comprising co-molding the annular inner liner and the outshell in situ in a single mold. 7. A method as claimed in claim 6 wherein the outshell and the annular liner are both co-injection molded, comprising injection molding of the outshell by horizontal injection with a screw extruder with a L/D screw ratio of about 32 in four progressively increasing temperature zones preferably ranging from 160 - 240°C and at an injection pressure in the range of 700 - 1800 kg/cm2, the annular liner being injection molded by vertical molding over three temperature zones ranging from a temperature of 120 - 185°C at a L/D of the screw of about 28 and at an injection pressure in the range of 600 - 1000 kg/cm2. 8. A method as claimed in claim 6 wherein the outshell and the annular inner liner are both compression molded. 9. A method as claimed in claim 6 wherein the outshell is injection molded and the annular inner liner is compression molded. 10. A method as claimed in claim 6 wherein the outshell and the annular inner liner are both injection molded. 11. A plastic closure cap substantially as described hereinbefore and with reference to the foregoing example and accompanying drawings. 12. A single step method for the manufacture of a plastic closure cap substantially as described hereinbefore and with reference to the foregoing example and accompanying drawings.

Documents:

1158-del-2002-abstract.pdf

1158-del-2002-claims.pdf

1158-del-2002-corrspondence-others.pdf

1158-del-2002-corrspondence-po.pdf

1158-del-2002-description (complete).pdf

1158-DEL-2002-Drawings.pdf

1158-del-2002-form-1.pdf

1158-del-2002-form-13.pdf

1158-del-2002-form-19.pdf

1158-del-2002-form-2.pdf

1158-del-2002-form-26.pdf

1158-del-2002-form-5.pdf

1158-del-2002-gpa.pdf