CA1156973A - Composite closure - Google Patents
Composite closureInfo
- Publication number
- CA1156973A CA1156973A CA000361257A CA361257A CA1156973A CA 1156973 A CA1156973 A CA 1156973A CA 000361257 A CA000361257 A CA 000361257A CA 361257 A CA361257 A CA 361257A CA 1156973 A CA1156973 A CA 1156973A
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- CA
- Canada
- Prior art keywords
- liner
- composite closure
- accordance
- plastic
- annular
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
ABSTRACT OF THE DISCLOSURE
A composite closure having a plastic cap with specially configured pedestals that are interconnected to a plastic liner. In one embodiment, the pedestals each have an overhang, such as a mushroom-shaped head, to provide a mechanical interlock with the liner. In other embodiments, the pedestals each have a fusible heat concentration zone that is fused to the liner as the liner is compression molded and heated in the cap.
In one embodiment, the fusible pedestals are each cylindrical. In another embodiment, the fusible pedestals are each in the shape of a pyramid.
A composite closure having a plastic cap with specially configured pedestals that are interconnected to a plastic liner. In one embodiment, the pedestals each have an overhang, such as a mushroom-shaped head, to provide a mechanical interlock with the liner. In other embodiments, the pedestals each have a fusible heat concentration zone that is fused to the liner as the liner is compression molded and heated in the cap.
In one embodiment, the fusible pedestals are each cylindrical. In another embodiment, the fusible pedestals are each in the shape of a pyramid.
Description
~L~5~7;3 CO~POSITE CLOSURE
BACKGROUND OE' THE INVENTION
This invention relates to closures, and more particularly, to a composite plastic closure for bottles.
Over the years metal crowns have been lined with various materials such as cork, rubber, thermosetting plastic and thermoplastic. Repre-sentative of the many crowns lined with such material are those shown in U.S. Patent Nos. 1,486,937,
BACKGROUND OE' THE INVENTION
This invention relates to closures, and more particularly, to a composite plastic closure for bottles.
Over the years metal crowns have been lined with various materials such as cork, rubber, thermosetting plastic and thermoplastic. Repre-sentative of the many crowns lined with such material are those shown in U.S. Patent Nos. 1,486,937,
2,548,305, 2~654~913, 2,684,774, ~,688,776, 2,696,318, 2,823,422, 2l834,498, 2,84~,~58, 2,952,035, 3,183,144, 3,278,985 and 3,300,072. These prior art crowns have met with varying degrees of success.
Recently, the advantages of plastic crowns and closures have been recognized. The physical characteristics and nature of plastics, however, such ; ~ as their melting and plastic deformation temper-atures, and their resiliency, impact and compression strengths, at molding and refrigeration temperatures, present different structural problems in molding plastic closures than in metal closures.
In prior art plastic closures, for example, the wall thickness is confined to a limited range, i.e., the wall must be thin enough to permit axial removal and deflection of the threaded skirt of the closure from the plunger, but thick enough to support the necessary thread height and profile. The threads of conventional plastic closures are also limited to a certain amount of t~per to permit deflection and removal of the threaded skirt from the plunger.
In conventional plastic closures, such as polypropylene closures, the closures have low impact strength and fail a drop test in the refrigeration range of 32-40 degrees F.
,~
D~ 73 It is therefore desirable to provide an improved plastic closure which overcomes most, if not all, of the above disadvantages.
SUMMARY OF THÆ INVENTI ON
An improved composite closure for bottles and other containers is disclosed which includes a plastic cap having a top wall portion and a depending annular skirt portion. The depending skirt portion includes inwardly extending, liner-retaining lip means spaced from the top lQ wall portion and defining a recess therewith. The closure further includes a plastic liner adapted to sealingly engage an associated container, the liner including an annular sealing portion disposed against and retained by the liner-retaining lip means. The annular sealing portion of the liner 15 substantially fills the annular recess of the closure cap, and is adapted to engage a generally outwardly facing surface of the container to which the closure is fitted.
The top wall portion of the closure cap preferably includes integral liner-retention means comprising at least 20 one liner-engaging projection or pedestal. In one embodiment, a plurality of mushroom-shaped liner-engaging pedestaIs are provided for interlockingly engaging the plastic liner. In another embodiment, a plurality of cylindrical liner-engaging pedestals are provided for fusing to the plastic liner. In 25 a further embodiment, a plurality of pyramidal liner-engaging pedestals are provided for fusing to the plastic liner.
In order to determine whether the container to which the closure has been applied has been opened, the closure includes a pilfer band detachably connected to the 30 skirt portion o~ the plastic aap.
A moxe detailed explanation of the invention is provided in the following description and appended claims taken in conjunction with the accompan~ing drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a cross-sectional view of a composite plastic closure in accordance with principles of the present invention, that has been screwed onto a container to provide a fluid tight seal with its finish;
FIGURE 2 is a bottom plan view of the underside of the cap of the composite closure with greatly magnified portions broken away for ease of clarity and understanding;
FIGURE 3 is a greatly enlarged perspective view of some of the mushroom-shaped pedestals of the closure, with portions of the cap's top wall shown in cross-section;
FIGURE 4 is a cross-sectional view of some of the mushroom-shaped pedestals of the cap;
FIGURE 5 is a cross-sectional view similar to Figure 4, but showing the liner in interlocking engagement with the mushroom-shaped pedestals;
FIGURE 6 is an enlarged cross-sectional view of another composite plastic closure having fusible cylindrical pedestals in accordance with principles of the present invention;
FIGURE 7 is a greatly magnified perspective view of some of the fusible cylindrical pedestals of the composite closure of Figure 6 and FIGURE 8 is a greatly magnified perspective view of some of the fusible pyramid-shaped pedestals of another composite plastic closure in accordance with principles of the present invention.
Referring to Figure 1 of the drawings, a composite plastic closure 100 is provided to close and fluidly seal the finish o a threaded bottle 102 or other containers filled wi~h a liquid, such as a ~56~73 carbonated beverage. Composite closure has a resilient plastic cap 104, which is sometimes referred to as a shell or crown, and has a resilient fluid-impervious plastic liner or seal 106. Cap 104 is preferably made of moldable thermoplastic, such as polypropylene or polyethylene. Other materials can also be used. Liner 106 is preferably ~ade of moldable thermoplastic, such as polyvinyl chloride ~PVC). Other liner materials, such as ethylene vinyl acetate ~EVA) can also be used.
In order to increase the strength of the cap, the cap has spun plastic portions that provide a spiral molecular orientation, i.e., spirally orientated molecules 108. The spiral orientation gives the cap greater hoop strength and crack resistance than plastic caps formed without spiral orientation. The spun plastic material provides good impact strength and enables the cap to pass a drop test in the refrigeration temperature range of 32~40 degrees F.
In the preferred embodiment, cap 104 is of a one-piece unitary construction and is made of a polypropylene homopolymer. All the parts and components of the plastic cap 104 are integrally connected to each other~ The cap 104 has a top wall disc-shaped portion or surface 110 that is sometimes referred to as the ~top," and an annular peripheral skirt 112 depending from the top }10. Top 110 has a generally flat outer surface 110a and an inner 8ur~ace that provides an underside 110b. The circular edge or corner 110c formed by the intersection of the top and the skirt is rounded or chamfered.
As shown in Figure 6 skirt 112 has internal threads 114 and an internal annular lip 116 that ~ ~5~i~73 provides a retainer to retain and confine the annular bead portion 106a of liner 106 and serves to ~upport and seal against a cylindrical sleeve d~ring the liner-forming process. As explained later, annular bead portion 106a advantageously seals against the finish of the bottle to fluidly seal any irregularities, such as bumps or unevenness in the finish. Retainer 116 is inclined and converges radially inward away from top 110.
In the illustrative embodiment, the exterior surface of skirt 112 has circumferentially spaced vertical finger-~ripping ribs 120 to facilitate gripping of the cap. The vertical ribs terminate in an outer rim 124 spaced below top 110. Rim 124 has an inwardly inclined annular shoulder 126 tbat provides the end skirt 112.
In order to indicate whether the closure 100 has been opened after the closure 100 has been inserted and screwed onto container 102l a heat-shrinkable detachable pilfer-band or tamper-proof band 128 is provided at the end of the skirt by a plurality of frangible members or bridges 130. When formed, pilfer-band 12B is biased radially inward from skirt 112 to provide a frusto-conical band having a minimum inside diameter that is less than the inside diameter of the skirt. The band is subsequently stretched, expanded and lifted to provide a circumferential or~ cylindrical portion havin~ an inside diameter approximately equal to the inside diameter of ~he skir~ 112 to enable the cap 104 to be inserted onto the container 102. The cylindrical band has a resilient memory and when reheated will assume its original frusto-conical shape.
~L56~3 After the composite plastic closure 100 has been inserted and screwed onto the container 102, pilfer-band 128 is heated to shrink about and engag2 the bottleneck. When closure 100 is unscrewed to open the bottle 102, pilfer-band 128 will fracture or break in selected areas. In the preferred embodiment, some of the frangible bridges 130 are thicker than others so that when the closure 100 is removed from the bottle, the pilfer-band will tear into one or more pieces and still be attached to the closure 100 by the thicker bridges. In some circumstances it may be desirable that the bridges 130 all have the same thickness and be only horizontally scored so that the pilfer-band 128 will remain on the bottle 102 when the closure 100 is removed.
In order to provide a secure mechanical interconnection between the liner 106 and the cap 104, the cap has a plurality of liner-engaging pedestals 132 that interlockingly engage liner 106.
Pedestals 132 extend vertically from the underside llOb of cap-top 110 to a position above the cap's annular lip 116. As shown in Figures 2-5, the pedestals 132 are spaced apart from each other in a grid-like array or matrix in longitudinal parallel rows and lateral parallel rows to define a plurality of liner-receiving passageways, channels or spaces 134 therebetween to receive the liner-forming plastic 106. Liner-receiving spaces 134 and pedestals 132 are circumferentially bounded and surrounded by skirt 112 ~Figure 1).
Each pedestal 132 ~Figures 3-5) is formed with a generally upright, vertical body 136 extending in the upright ~axial) direction. Pedestal-body 136 has a free end or head 138 that is spaced away from the top 110 of cap 10~. In the illustrative embodiment, pedestal-body 136 has a generally square cross-section.
In the process of forming the pedestals 132, the free end 136 (Figures 3-5) of pedestal-body 138 is upset, such as by compression and/or heating, to form a mushroom-shaped head with an overhang 140 that extends outwardly of the body 138 in a direction generally transverse to the upright direction.
Overhangs 140 provide a mechanical interlock between pedestal~ 132 and liner 106~ The holding strength of the pedestals and the tear strength of the mechanical connection between the liner 106 and pedestals 132, is proportional to the diameter and extent of the overhang 110 of pedestals 132, the number of pedestals 132 and the spacing 134 between pedestals.
For a given number of pedestals, increasing the diameter and extent of the overhang 110 of the mushroom shaped head will increase the tear strength 2~ (peel strength) of the closure. Therefore, by varying the amount of the overhang, the peel strength of the pedestals can be varied to a desired amount, such as between two and six pounds. This versatility is important because it permits the liner 106 to be detached or stripped from the pedestals 132 with a minimum amount of effort at a later time. The maximum bond and holding strength between the pedestals 132 and liner 106 occurs when the overhangs 14a o~ the pedestals contact each other.
Referring now to the plastic liner 106r the liner 106 has a centrally disposed circular disa-shaped portion or membrane 106b ~Figure 1) that extends across and is connected to and circumscribed by an annular sealing bead 106a. DisC portlon 106b 3S engages the underside 110a of cap-top 110 and extends to a position beneath the mushroom-shaped heads 13 to completely cover and overlie pedestals 132.
Annular bead 106a is confined in the channel between top 110 and retainer 116. In the illustrative embodiment, the outer face of bead 106a has a rounded lower portion 142 (Figure 6) that is shaped complementary to the internal rounded corner that connects the top 110 to skirt 112, and has an outer upper frusto-conical portion 144 that is inclined and converges radially inward away from top 110, and engages retai~er 116. The inner face of bead 106a has a vertical lower portion or shoulder 146 and an upper frusto-conical sealing portion 148 that is inclined and diverges radially outward from shoulder 146. Upper sealing portion 148 resiliently seals and seats against the finish and rim of the bottle to abut against and fluidly seal any irregularities, such as bumps or unevenness, in the finish.
When certain types of thermoplastic liners 2a 106 are used, such as EVA liners, the liner 106 is thermally fused and bonded to pedestals 132 (Figure 5) as it is compression molded and heated during the liner-forming process. This provides a thermo-connection in addition to the mechanical interlock ~5 provided by the mushroom-shaped pedestals 13~ (Figure 5). For other materials, such as PVC, the liner may not be fused to the pedestals when it is compression molded and heated, but it is still securely mechanically held by the mushroom-shaped pedestals 13~.
Advanta~eously/ the resul~ant secure mechanical interconnection between cap 104 and liner 106 attributable to the holding strength o~ the mushroom-shaped pedestals 132 permits the liner to be molded without heating the cap, or at least without ~L56~73 heating the non-pedestal portions of the ~ap, ~o its melting and plastic deformation temperature, thereby minimizing distortion of the cap when the liner is formed.
It will be appreciated that pedestals having heads or overhangs with other shapes could also be used to provide a mechanical interlock with the liner in accordance with principles of the present invention.
The composite plastic closure 150 shown in Figure 6 is identical to the composite closure 100 shown in Figure 1, except that the pedestals 152 are in the form of fusible cylindrical pedestals and do not have an overhang Each of the pedestals 152 (Figure 7) has a generally planar or flat end 154 with a circular edge 156 that defines at least part of a fusible heat concentration zone, that becomes : thermally fused to liner 106 (Figure 6) when liner 106 is compression molded and heated in cap 104 during the liner-forming process. The thermal bond between liner 106 and pedestals 152 provide a solid thermal interconnection between liner 106 and cap 104. Desirably, the shape and arrangement of the fusible pedestals 152 are such as to permit the pedestals to be heated to their melting and plastic deformation temperature for fusion with the liner 106, while the other portions of the cap 104 are kept cooler, thereby minimizing distortion of the cap when the liner is formed.
The composite plastic closuxe 160 shown in Figure 8 is identical to the composite closure 150 shown in ~igures 6 and 7, excep~ that the fusible pedestals 162 are pyramid-shaped and the bases 164 of the pyramids 162 in each lateral row 166 are contiguous. The apex or peak 168 of each pyramid 162 and the portions immediately adjacent thereto provides a fusible heat concentration zone 170 that becomes thermally fused to the molten liner-forming plastic as the liner is compression molded and heated in the cap during the liner-forming process. The fusible pyramid-shaped pedestals 162 also permit the pedestals to be heated to their melting and plastic deformation temperature for fusion to the liner 106, while the other portions o the cap are kept cooler so as to minimize distortion of the cap 104 when the liner is formed. Because of the shape, arrangement and high heat transfer capabilities of the pyramid-shaped pedestals 162, it is believed that the cap with pyramid-shaped pedestals 162 can be kept even cooler than a cap with cylindrical pedestals 152, when the liner is formed.
It was found that pyramids with a radius at the apex of approximately 0.002 inch had about the same adhesion (thermal connection strength) with a liner as 0.013 inch diameter cylindrical pedestals that were formed with a 50 mesh stainless steel screen~ Prior art closures provided only about one-fifth ~he adhesion tholding strength) of the pyramids and cylinders.
It will be appreciated by those skilled in the art, that fusible pedestals having other configurations can be used in accordance with principles of the present invention.
Although embodiments of the invention have been shown an described, it is to be understood that various modifications and subst~tutions can be made by those skilled in the art without departing from the novel spirit and scope of this invention.
Recently, the advantages of plastic crowns and closures have been recognized. The physical characteristics and nature of plastics, however, such ; ~ as their melting and plastic deformation temper-atures, and their resiliency, impact and compression strengths, at molding and refrigeration temperatures, present different structural problems in molding plastic closures than in metal closures.
In prior art plastic closures, for example, the wall thickness is confined to a limited range, i.e., the wall must be thin enough to permit axial removal and deflection of the threaded skirt of the closure from the plunger, but thick enough to support the necessary thread height and profile. The threads of conventional plastic closures are also limited to a certain amount of t~per to permit deflection and removal of the threaded skirt from the plunger.
In conventional plastic closures, such as polypropylene closures, the closures have low impact strength and fail a drop test in the refrigeration range of 32-40 degrees F.
,~
D~ 73 It is therefore desirable to provide an improved plastic closure which overcomes most, if not all, of the above disadvantages.
SUMMARY OF THÆ INVENTI ON
An improved composite closure for bottles and other containers is disclosed which includes a plastic cap having a top wall portion and a depending annular skirt portion. The depending skirt portion includes inwardly extending, liner-retaining lip means spaced from the top lQ wall portion and defining a recess therewith. The closure further includes a plastic liner adapted to sealingly engage an associated container, the liner including an annular sealing portion disposed against and retained by the liner-retaining lip means. The annular sealing portion of the liner 15 substantially fills the annular recess of the closure cap, and is adapted to engage a generally outwardly facing surface of the container to which the closure is fitted.
The top wall portion of the closure cap preferably includes integral liner-retention means comprising at least 20 one liner-engaging projection or pedestal. In one embodiment, a plurality of mushroom-shaped liner-engaging pedestaIs are provided for interlockingly engaging the plastic liner. In another embodiment, a plurality of cylindrical liner-engaging pedestals are provided for fusing to the plastic liner. In 25 a further embodiment, a plurality of pyramidal liner-engaging pedestals are provided for fusing to the plastic liner.
In order to determine whether the container to which the closure has been applied has been opened, the closure includes a pilfer band detachably connected to the 30 skirt portion o~ the plastic aap.
A moxe detailed explanation of the invention is provided in the following description and appended claims taken in conjunction with the accompan~ing drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a cross-sectional view of a composite plastic closure in accordance with principles of the present invention, that has been screwed onto a container to provide a fluid tight seal with its finish;
FIGURE 2 is a bottom plan view of the underside of the cap of the composite closure with greatly magnified portions broken away for ease of clarity and understanding;
FIGURE 3 is a greatly enlarged perspective view of some of the mushroom-shaped pedestals of the closure, with portions of the cap's top wall shown in cross-section;
FIGURE 4 is a cross-sectional view of some of the mushroom-shaped pedestals of the cap;
FIGURE 5 is a cross-sectional view similar to Figure 4, but showing the liner in interlocking engagement with the mushroom-shaped pedestals;
FIGURE 6 is an enlarged cross-sectional view of another composite plastic closure having fusible cylindrical pedestals in accordance with principles of the present invention;
FIGURE 7 is a greatly magnified perspective view of some of the fusible cylindrical pedestals of the composite closure of Figure 6 and FIGURE 8 is a greatly magnified perspective view of some of the fusible pyramid-shaped pedestals of another composite plastic closure in accordance with principles of the present invention.
Referring to Figure 1 of the drawings, a composite plastic closure 100 is provided to close and fluidly seal the finish o a threaded bottle 102 or other containers filled wi~h a liquid, such as a ~56~73 carbonated beverage. Composite closure has a resilient plastic cap 104, which is sometimes referred to as a shell or crown, and has a resilient fluid-impervious plastic liner or seal 106. Cap 104 is preferably made of moldable thermoplastic, such as polypropylene or polyethylene. Other materials can also be used. Liner 106 is preferably ~ade of moldable thermoplastic, such as polyvinyl chloride ~PVC). Other liner materials, such as ethylene vinyl acetate ~EVA) can also be used.
In order to increase the strength of the cap, the cap has spun plastic portions that provide a spiral molecular orientation, i.e., spirally orientated molecules 108. The spiral orientation gives the cap greater hoop strength and crack resistance than plastic caps formed without spiral orientation. The spun plastic material provides good impact strength and enables the cap to pass a drop test in the refrigeration temperature range of 32~40 degrees F.
In the preferred embodiment, cap 104 is of a one-piece unitary construction and is made of a polypropylene homopolymer. All the parts and components of the plastic cap 104 are integrally connected to each other~ The cap 104 has a top wall disc-shaped portion or surface 110 that is sometimes referred to as the ~top," and an annular peripheral skirt 112 depending from the top }10. Top 110 has a generally flat outer surface 110a and an inner 8ur~ace that provides an underside 110b. The circular edge or corner 110c formed by the intersection of the top and the skirt is rounded or chamfered.
As shown in Figure 6 skirt 112 has internal threads 114 and an internal annular lip 116 that ~ ~5~i~73 provides a retainer to retain and confine the annular bead portion 106a of liner 106 and serves to ~upport and seal against a cylindrical sleeve d~ring the liner-forming process. As explained later, annular bead portion 106a advantageously seals against the finish of the bottle to fluidly seal any irregularities, such as bumps or unevenness in the finish. Retainer 116 is inclined and converges radially inward away from top 110.
In the illustrative embodiment, the exterior surface of skirt 112 has circumferentially spaced vertical finger-~ripping ribs 120 to facilitate gripping of the cap. The vertical ribs terminate in an outer rim 124 spaced below top 110. Rim 124 has an inwardly inclined annular shoulder 126 tbat provides the end skirt 112.
In order to indicate whether the closure 100 has been opened after the closure 100 has been inserted and screwed onto container 102l a heat-shrinkable detachable pilfer-band or tamper-proof band 128 is provided at the end of the skirt by a plurality of frangible members or bridges 130. When formed, pilfer-band 12B is biased radially inward from skirt 112 to provide a frusto-conical band having a minimum inside diameter that is less than the inside diameter of the skirt. The band is subsequently stretched, expanded and lifted to provide a circumferential or~ cylindrical portion havin~ an inside diameter approximately equal to the inside diameter of ~he skir~ 112 to enable the cap 104 to be inserted onto the container 102. The cylindrical band has a resilient memory and when reheated will assume its original frusto-conical shape.
~L56~3 After the composite plastic closure 100 has been inserted and screwed onto the container 102, pilfer-band 128 is heated to shrink about and engag2 the bottleneck. When closure 100 is unscrewed to open the bottle 102, pilfer-band 128 will fracture or break in selected areas. In the preferred embodiment, some of the frangible bridges 130 are thicker than others so that when the closure 100 is removed from the bottle, the pilfer-band will tear into one or more pieces and still be attached to the closure 100 by the thicker bridges. In some circumstances it may be desirable that the bridges 130 all have the same thickness and be only horizontally scored so that the pilfer-band 128 will remain on the bottle 102 when the closure 100 is removed.
In order to provide a secure mechanical interconnection between the liner 106 and the cap 104, the cap has a plurality of liner-engaging pedestals 132 that interlockingly engage liner 106.
Pedestals 132 extend vertically from the underside llOb of cap-top 110 to a position above the cap's annular lip 116. As shown in Figures 2-5, the pedestals 132 are spaced apart from each other in a grid-like array or matrix in longitudinal parallel rows and lateral parallel rows to define a plurality of liner-receiving passageways, channels or spaces 134 therebetween to receive the liner-forming plastic 106. Liner-receiving spaces 134 and pedestals 132 are circumferentially bounded and surrounded by skirt 112 ~Figure 1).
Each pedestal 132 ~Figures 3-5) is formed with a generally upright, vertical body 136 extending in the upright ~axial) direction. Pedestal-body 136 has a free end or head 138 that is spaced away from the top 110 of cap 10~. In the illustrative embodiment, pedestal-body 136 has a generally square cross-section.
In the process of forming the pedestals 132, the free end 136 (Figures 3-5) of pedestal-body 138 is upset, such as by compression and/or heating, to form a mushroom-shaped head with an overhang 140 that extends outwardly of the body 138 in a direction generally transverse to the upright direction.
Overhangs 140 provide a mechanical interlock between pedestal~ 132 and liner 106~ The holding strength of the pedestals and the tear strength of the mechanical connection between the liner 106 and pedestals 132, is proportional to the diameter and extent of the overhang 110 of pedestals 132, the number of pedestals 132 and the spacing 134 between pedestals.
For a given number of pedestals, increasing the diameter and extent of the overhang 110 of the mushroom shaped head will increase the tear strength 2~ (peel strength) of the closure. Therefore, by varying the amount of the overhang, the peel strength of the pedestals can be varied to a desired amount, such as between two and six pounds. This versatility is important because it permits the liner 106 to be detached or stripped from the pedestals 132 with a minimum amount of effort at a later time. The maximum bond and holding strength between the pedestals 132 and liner 106 occurs when the overhangs 14a o~ the pedestals contact each other.
Referring now to the plastic liner 106r the liner 106 has a centrally disposed circular disa-shaped portion or membrane 106b ~Figure 1) that extends across and is connected to and circumscribed by an annular sealing bead 106a. DisC portlon 106b 3S engages the underside 110a of cap-top 110 and extends to a position beneath the mushroom-shaped heads 13 to completely cover and overlie pedestals 132.
Annular bead 106a is confined in the channel between top 110 and retainer 116. In the illustrative embodiment, the outer face of bead 106a has a rounded lower portion 142 (Figure 6) that is shaped complementary to the internal rounded corner that connects the top 110 to skirt 112, and has an outer upper frusto-conical portion 144 that is inclined and converges radially inward away from top 110, and engages retai~er 116. The inner face of bead 106a has a vertical lower portion or shoulder 146 and an upper frusto-conical sealing portion 148 that is inclined and diverges radially outward from shoulder 146. Upper sealing portion 148 resiliently seals and seats against the finish and rim of the bottle to abut against and fluidly seal any irregularities, such as bumps or unevenness, in the finish.
When certain types of thermoplastic liners 2a 106 are used, such as EVA liners, the liner 106 is thermally fused and bonded to pedestals 132 (Figure 5) as it is compression molded and heated during the liner-forming process. This provides a thermo-connection in addition to the mechanical interlock ~5 provided by the mushroom-shaped pedestals 13~ (Figure 5). For other materials, such as PVC, the liner may not be fused to the pedestals when it is compression molded and heated, but it is still securely mechanically held by the mushroom-shaped pedestals 13~.
Advanta~eously/ the resul~ant secure mechanical interconnection between cap 104 and liner 106 attributable to the holding strength o~ the mushroom-shaped pedestals 132 permits the liner to be molded without heating the cap, or at least without ~L56~73 heating the non-pedestal portions of the ~ap, ~o its melting and plastic deformation temperature, thereby minimizing distortion of the cap when the liner is formed.
It will be appreciated that pedestals having heads or overhangs with other shapes could also be used to provide a mechanical interlock with the liner in accordance with principles of the present invention.
The composite plastic closure 150 shown in Figure 6 is identical to the composite closure 100 shown in Figure 1, except that the pedestals 152 are in the form of fusible cylindrical pedestals and do not have an overhang Each of the pedestals 152 (Figure 7) has a generally planar or flat end 154 with a circular edge 156 that defines at least part of a fusible heat concentration zone, that becomes : thermally fused to liner 106 (Figure 6) when liner 106 is compression molded and heated in cap 104 during the liner-forming process. The thermal bond between liner 106 and pedestals 152 provide a solid thermal interconnection between liner 106 and cap 104. Desirably, the shape and arrangement of the fusible pedestals 152 are such as to permit the pedestals to be heated to their melting and plastic deformation temperature for fusion with the liner 106, while the other portions of the cap 104 are kept cooler, thereby minimizing distortion of the cap when the liner is formed.
The composite plastic closuxe 160 shown in Figure 8 is identical to the composite closure 150 shown in ~igures 6 and 7, excep~ that the fusible pedestals 162 are pyramid-shaped and the bases 164 of the pyramids 162 in each lateral row 166 are contiguous. The apex or peak 168 of each pyramid 162 and the portions immediately adjacent thereto provides a fusible heat concentration zone 170 that becomes thermally fused to the molten liner-forming plastic as the liner is compression molded and heated in the cap during the liner-forming process. The fusible pyramid-shaped pedestals 162 also permit the pedestals to be heated to their melting and plastic deformation temperature for fusion to the liner 106, while the other portions o the cap are kept cooler so as to minimize distortion of the cap 104 when the liner is formed. Because of the shape, arrangement and high heat transfer capabilities of the pyramid-shaped pedestals 162, it is believed that the cap with pyramid-shaped pedestals 162 can be kept even cooler than a cap with cylindrical pedestals 152, when the liner is formed.
It was found that pyramids with a radius at the apex of approximately 0.002 inch had about the same adhesion (thermal connection strength) with a liner as 0.013 inch diameter cylindrical pedestals that were formed with a 50 mesh stainless steel screen~ Prior art closures provided only about one-fifth ~he adhesion tholding strength) of the pyramids and cylinders.
It will be appreciated by those skilled in the art, that fusible pedestals having other configurations can be used in accordance with principles of the present invention.
Although embodiments of the invention have been shown an described, it is to be understood that various modifications and subst~tutions can be made by those skilled in the art without departing from the novel spirit and scope of this invention.
Claims (30)
EXCLUSIVE PROPERTY OF PRIVILEGE IS CLAIMED ARE
DEFINED AS FOLLOWS:
1. A composite closure for a container, comprising:
a plastic cap including a top wall portion, and a depending annular skirt portion, said skirt portion having an inwardly extending, liner-retaining annular lip spaced from said top wall portion and defining a recess therewith, and a plastic liner adapted to sealingly engage said container disposed within said cap, said liner including an annular sealing portion disposed against said lip and substantially filling said recess.
a plastic cap including a top wall portion, and a depending annular skirt portion, said skirt portion having an inwardly extending, liner-retaining annular lip spaced from said top wall portion and defining a recess therewith, and a plastic liner adapted to sealingly engage said container disposed within said cap, said liner including an annular sealing portion disposed against said lip and substantially filling said recess.
2. A composite closure in accordance with claim 1, and a plurality of liner engaging pedestals integral with said top wall portion.
3. A composite closure in accordance with claim 2, wherein at least some of said pedestals include a heat concentration zone thermally fused to said plastic liner.
4. A composite closure in accordance with claim 2, wherein at least some of said pedestals include a mushroom-shaped portion that interlockingly engages said plastic liner.
5. A composite closure for a container, comprising:
a molded plastic cap having a top wall portion, and a depending annular skirt, said skirt including an internal thread formation and an integral inwardly extending annular lip spaced from said top wall portion and defining an annular recess therewith;
and a plastic liner including an annular sealing portion adapted to sealingly engage an outwardly facing surface of said container, said sealing portion being retained by said annular lip and substantially filling said annular recess.
a molded plastic cap having a top wall portion, and a depending annular skirt, said skirt including an internal thread formation and an integral inwardly extending annular lip spaced from said top wall portion and defining an annular recess therewith;
and a plastic liner including an annular sealing portion adapted to sealingly engage an outwardly facing surface of said container, said sealing portion being retained by said annular lip and substantially filling said annular recess.
6. A composite closure in accordance with claim 5, wherein said annular lip has an inside diameter less than the inside diameter of said thread formation.
7. A composite closure in accordance with claim 5, and at least one projection extending integrally from said top wall portion in engagement with said plastic liner.
8. A composite closure in accordance with claim 7, wherein said projection is thermally fused to said plastic liner.
9. A composite closure in accordance with claim 7 wherein said projection is mechanically connected to said plastic liner.
10. A composite closure in accordance with claim 5, and a pilfer band detachably connected to said annular skirt.
11. A composite closure in accordance with claim 10, wherein said pilfer band is heat shrinkable and is detachably connected to said annular skirt by spaced bridge means.
12. A composite closure in accordance with claim 5, 6, or 7, wherein said annular recess has a maximum internal diameter greater than the inside diameter of said thread formation.
13. A composite closure for a container, comprising:
a molded plastic cap having a top wall portion, and an annular skirt including an internal thread formation and an inwardly extending annular lip spaced from said top wall portion and defining an annular recess therewith; and a plastic liner including a relatively thick annular sealing bead portion adapted to sealingly engage an outwardly facing surface of said container, said sealing head portion being retained by said annular lip and substantially filling said annular recess.
a molded plastic cap having a top wall portion, and an annular skirt including an internal thread formation and an inwardly extending annular lip spaced from said top wall portion and defining an annular recess therewith; and a plastic liner including a relatively thick annular sealing bead portion adapted to sealingly engage an outwardly facing surface of said container, said sealing head portion being retained by said annular lip and substantially filling said annular recess.
14. A composite closure in accordance with claim 13, and at least one liner-engaging projection extending integrally from said top wall portion.
15. A composite closure for a container, comprising:
a plastic cap having a top wall portion, a generally cylindrical skirt portion, an inwardly extending annular lip on said skirt portion spaced from said top wall portion and defining an annular recess therewith, and a plurality of liner-engaging projections on the inside surface of said top wall portion; and a plastic sealing liner disposed within said cap, said liner including an annular sealing bead portion adapted to sealingly engage said container, said sealing portion substantially filling said annular recess, said liner engaging said liner-engaging projections.
a plastic cap having a top wall portion, a generally cylindrical skirt portion, an inwardly extending annular lip on said skirt portion spaced from said top wall portion and defining an annular recess therewith, and a plurality of liner-engaging projections on the inside surface of said top wall portion; and a plastic sealing liner disposed within said cap, said liner including an annular sealing bead portion adapted to sealingly engage said container, said sealing portion substantially filling said annular recess, said liner engaging said liner-engaging projections.
16. A composite closure in accordance with claim 15, wherein at least some of said projections include a heat concentration zone thermally fused to said sealing liner.
17. A composite closure in accordance with claim 16, wherein said projections including said heat concentration zone each have a pyramidal configuration including an apex providing said heat concentration zone.
18. A composite closure in accordance with claim 16, wherein said projections including said heat concentration zone each have a cylindrical configuration including a circular edge providing said heat concentration zone.
19. A composite closure in accordance with claim 15, wherein at least some of said projections include a mushroom-shaped portion mechanically connected to said sealing liner.
20. A composite closure in accordance with claim 15, and pilfer band means detachably connected to said skirt portion.
21. A composite closure in accordance with claim 20, wherein said pilfer band means comprise a heat-shrinkable pilfer band.
22. A composite closure in accordance with claim 15, wherein said liner-engaging projections are arranged in a grid-like array on the inside surface of said top wall portion.
23. A composite closure in accordance with claim 15, wherein at least some of said projections have a generally upright body extending in a generally upright direction and have portions extending outwardly of said body in a direction generally traverse to said upright direction for providing a head having an overhang to interlockingly engage said plastic liner.
24. A composite closure in accordance with claim 15, wherein said sealing liner includes a centrally disposed portion connected to said annular sealing portion and substantially overlying said projections.
25. A composite closure, comprising:
a plastic cap including a top wall portion, a depending annular skirt portion having integral, inwardly extending lip means spaced from said top wall portion and defining a recess therewith, and liner retention means integral with said top wall portion, and a substantially fluid-impervious plastic sealing liner positioned adjacent said top wall portion including a peripheral sealing portion positioned adjacent said skirt portion, said lip means confining said peripheral sealing portion within said recess to retain said plastic liner within said plastic cap, said liner-retention means retaining said plastic liner in position within said plastic cap.
a plastic cap including a top wall portion, a depending annular skirt portion having integral, inwardly extending lip means spaced from said top wall portion and defining a recess therewith, and liner retention means integral with said top wall portion, and a substantially fluid-impervious plastic sealing liner positioned adjacent said top wall portion including a peripheral sealing portion positioned adjacent said skirt portion, said lip means confining said peripheral sealing portion within said recess to retain said plastic liner within said plastic cap, said liner-retention means retaining said plastic liner in position within said plastic cap.
26. A composite closure, comprising:
a plastic cap including a top wall portion, and a depending annular skirt portion having an internal thread formation thereon and an integral, inwardly extending, liner-retaining annular lip, said annular lip being spaced from said top wall portion and defining an annular recess therewith, said plastic cap in-cluding a plurality of liner engaging projections extending integrally from said top wall portion, and a plastic sealing liner formed in said cap disposed adjacent said top wall portion, and including an annular sealing bead portion positioned against said annular lip, said projections engaging said plastic liner for retaining said liner within said plastic cap.
a plastic cap including a top wall portion, and a depending annular skirt portion having an internal thread formation thereon and an integral, inwardly extending, liner-retaining annular lip, said annular lip being spaced from said top wall portion and defining an annular recess therewith, said plastic cap in-cluding a plurality of liner engaging projections extending integrally from said top wall portion, and a plastic sealing liner formed in said cap disposed adjacent said top wall portion, and including an annular sealing bead portion positioned against said annular lip, said projections engaging said plastic liner for retaining said liner within said plastic cap.
27. A composite closure in accordance with claim 26, wherein said projections are thermally fused to said plastic liner.
28. A composite closure in accordance with claim 26, wherein said projections mechanically retain said liner within said plastic cap.
29. A composite closure in accordance with claim 26, and a pilfer band at least partially detachably connected to said skirt portion by a plurality of spaced, frangible bridge means.
30. A composite closure in accordance with claim 29, wherein said pilfer band is heat-shrinkable.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000361257A CA1156973A (en) | 1980-09-30 | 1980-09-30 | Composite closure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000361257A CA1156973A (en) | 1980-09-30 | 1980-09-30 | Composite closure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1156973A true CA1156973A (en) | 1983-11-15 |
Family
ID=4118015
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000361257A Expired CA1156973A (en) | 1980-09-30 | 1980-09-30 | Composite closure |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1156973A (en) |
-
1980
- 1980-09-30 CA CA000361257A patent/CA1156973A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |