Child resistant package

Abstract: A child resistant closure (10) adapted to be used with a container to provide a child resistant package comprising a closure having a base wall (11) and a peripheral skirt (12) with internal threads (13) adapted to engage complementary threads on the container. The closure is provided with a plurality of circumferentially spaced flexible fins (15) which frictionally engage the apex only of an annular bead on the container to provide resistance to closure back off in order to resist unthreading of the closure from the container. The closure is be provided with a tab (21) which is engageable with a projection on the container to prevent unthreading of the closure except when the tab is depressed. In another form, a cylindrical surface on the skirt frictionally engages solely the apex of the annular bead on the container. The cylindrical surface may be a continuous surface or a series of closely spaced annular serrations and alternating fine grooves. The closure may also be used without a tab to provide a secondary seal on a conventional threaded closure.

Description: This invention relates to a child resistant package. Background and Summary of the Invention In the prior art, it has been common to provide child resistant closures which include as a feature some construction for preventing or resisting rotation of the closure and at the same time maintaining a seal to prevent leakage of contents during the initial unthreading of the closure from the container. Thus, U.S. Patent 3,971,487 (nearest prior art) discloses the concept of an internal annular bead on the closure engaging a complementary bead on the finish of the container so that when the closure is initially rotated, the base of the closure is maintained in sealing contact with the finish even though the threads have begun to lose contact. In such a construction, the use of a solid closure bead in connection with the solid bead on the container has a problem requiring high torque for application and removal. In addition, due to normal dimensional tolerances in an axial direction, the seal is not maintained when the closure is fully applied. Such closures utilize a depressable tab that engages a projection on a container so that when the tab is depressed, the closure can be rotated to remove the closure from the container. Certain containers especially those for anti-freeze are sealed with closures that have an aluminium foil disk induction sealed over the mouth of the finish. During the process of activating the induction seal, the closure may become loose and is usually retightened before the containers are shipped. While the induction seal prevents leakage it is undesirable to have loose closures, especially child resistant closures. Further, one piece child resistant closures having a tab on the closure and an abutment on the finish usually have a space between them such that the closure can be moved several degrees of rotation in the unscrewing direction before the tab contacts the abutment. When this occurs, the closure is free to move vertically with respect to the finish because the top of the closure threads are not in contact with the bottom of the container threads. In Specification EP-A-0 232 856 there is disclosed a container and cap having interengaging screw threads and a sealing ring provided on the inside of the top wall of the cap. The sealing function of the sealing ring is maintained by means of cooperating ratchet rings formed on the container and the inside wall of the cap skirt. Among the objectives of the present invention are to provide a child resistant closure which will maintain the oriented position with respect to the container when the closure is applied; which will resist inadvertent rotation as by vibration and thereby maintain a seal except when sufficient force is supplied to rotate the closure; which prevents the closure from moving out of sealing position when the closure is being unthreaded until the threads elevate the closure out of sealing position; which functions over a greater range of tolerances; which requires minimal torque to apply; which does not require excessive torque to remove; which closure can be utilized in connection with conventional containers having a projection and incorporating a tab with the closure for engaging the projection upon rotation of the closure beyond a certain point unless the tab is depressed; which closure can also be utilized on a container which does not require a tab; which will effectively deter and resist rotation without the necessity of close tolerances between the closure and the container; and which provides a secondary seal at the apex of an annular bead on the container. In accordance with the invention there is provided a package comprising a container having a finish with external threads and having an annular bead on the container spaced below the threads, said bead having an apex, a plastic closure having a base wall and a peripheral skirt with complementary internal threads adapted to engage said threads on the container, a deflectable portion on said closure and an abutment on the container, said portion being adapted to extend into the path of the abutment on a container such that the deflectable portion can be deflected past the abutment when the closure is applied to the container but will engage the abutment when the closure is grasped and rotated to remove the closure unless the deflectable portion is manually depressed, characterised in that said skirt of said closure has a cylindrical surface comprising a plurality of closely spaced annular serrations and fine grooves separating said serrations in alternating fashion, said serrations and associated fine grooves having an axial extent such that an interference fit will exist over a wide range of tolerances of the container finish and closure with the apex of the bead when the closure is fully applied as well as when the closure is rotated in retrograde fashion to the extent that any other seal between the closure and container is broken, even though the closure has not been rotated sufficiently to disengage the deflectable portion from the abutment on the container. Description of the Drawings Figure 1 is a plan view of a child resistant closure and container embodying the invention; Figure 2 is a vertical sectional view of the closure of Figure 1; Figure 3 is a bottom plan view of the closure; Figure 4 is a fragmentary sectional view on a greatly enlarged scale of a portion of the closure; Figure 5 is a plan view similar to that of Figure 1 but showing the closure rotated slightly in the opening direction; Figure 6 is a plan view of a modified closure; Figure 7 is a fragmentary plan view of another modified closure; Figures 8 A,B,C, and D are schematic views of the manner in which the closure embodying the invention functions; Figures 9 A,B,C, and D are schematic views of the manner in which a prior art closure functions. Description Referring to Figures 1 - 7, the child resistant closure 10 is shown as applied to a glass or plastic container G and is made of plastic material such as polypropylene. Closure 10 includes a base wall 11 and a peripheral wall or skirt 12 having internal threads 13 adapted to engage complementary threads 13a on the container G. The closure 10 includes a lower skirt portion 14 that has a greater diameter than the remainder of the skirt 12. An annular bead 20 having an apex is formed in the finish of the container G below the thread 13a (see Figure 4). In the form of the invention shown in Figure 6, a rectangular tab 21 is connected to the lower portion of skirt 12 intermediate its ends by an integral hinge 22 nearest one end which is the leading end when the closure is threaded on the container. The tab 21 extends outwardly and generally circumferentially and is positioned a sufficient distance from the skirt such that the outer or trailing end of tab 21 will contact an abutment or projection 23 on the finish of the container G which extends generally axially from the container into the path of the outer end. The abutment 23 on the finish is positioned such that its inner surface is approximately the same distance from the center line of the closure as is a radial projection 24 that extends radially from the skirt 23. This projection 24 is positioned immediately after the tab 21 in a clockwise direction as viewed in Figure 6. Unscrewing the closure 10 without depressing the tab 21 inward of the abutment 23 will cause the tab 21 to be wedged between the projection 24 on the closure skirt 12 and the abutment 23. The closure 10 further includes a second radial abutment 25 adjacent the trailing edge of tab 21 which functions to prevent the tab 21 of one closure 10 to interlock with another closure 10 when the closures are handled and stored in bulk such that they could not be readily sorted and oriented by a sorting machine for application to containers. The closure is applied by screwing it on the finish in the normal clockwise direction. As the closure is being applied the tab 21 cams past the abutment 23 because the inner end of the tab 21 is radially closer to the skirt 12 of the closure 10 than the outer end that contacts the abutment 23 on the finish. When the closure is unscrewed, the outer end of the tab 21 contacts the abutment 23 on the finish and stops rotation of the closure. Extreme force on the closure will cause the inner end of the tab 21 to come into contact with the projection 24 and prevent further rotation of the closure in the counterclockwise or unthreading direction. To remove the closure, one must manually depress the tab 21 inwardly toward the skirt of the closure while turning the closure until the tab is rotated past the abutment. When this occurs the closure may be unscrewed from the finish without continuously depressing the tab 21. In the form of the invention shown in Figures 1 - 5, the closure 10 is identical to that of Figure 6 except that the tab 30 is of the type shown in U.S. Patent 3,989,152. The tab 30 is connected at its ends to the skirt 12 and includes a projection 31 which engages the abutment 23 on the container unless the tab 30 is depressed. In the form of the invention shown in Figure 7, the closure comprises a tab 35 which extends circumferentially in a counterclockwise direction as viewed from the top so that the tab 35 flexes at a hinge 36 with respect to the closure when the closure is rotated past the projection 23 on the container. The closure is thus prevented from being removed by engagement of the free end of tab 35 with projection 23 on the container. In all other respects, the closure is like that shown in Figures 1 - 6. Current one piece child resistant closures require a substantial amount of force to depress a tab while rotating past an abutment on the container's finish. The present design is user friendly in that a much less force is necessary to depress the tab 35 when the tab 35 is depressed prior to the point where it would come into contact with the abutment 23. If the tab 35 is not depressed while the closure is being rotated in a counterclockwise or unthreading direction, the tab 35 will contact the abutment 23 and be deflected or bent outward and become wedged between the abutment 23 on the finish and the projection 24 on the closure. The distance from the center line of the finish to the inner side of the abutment is less than the distance from the center line of the closure to the tip of the projection. During application of the closure onto the finish in a normal manner for a screw cap, namely, in a clockwise direction as viewed from the top, the tab 35 will contact the inner edge of the abutment 23 and be deflected inward until the tab 35 is completely past the abutment 23. At that time, the tab 35 will again spring outward. When the closure 10 is fully applied and tightened, the tab 35 will be spaced some distance from the abutment 23 in the clockwise direction and in the extended position. When the closure is being removed by unscrewing in the opposite direction, the tab 35 will contact the abutment 23 and be deflected outward from its normal position until it becomes wedged against the abutment 23 on the finish and the projection 24 on the closure. Additional force in an effort to unscrew the closure will cause a type of shearing action on the tab but the closure 10 cannot be unscrewed. In practice, instructions may be printed on top of the closure such as "To Open Push Tab In While Turning". Following these directions, pushing the tab 35 in causes the tip of the tab 35 to rotate past the inner surface of the abutment 23 as the closure is unscrewed. Once the tab 35 has moved past the abutment, the closure can continue to be unscrewed, without holding the tab 35 in until it is fully removed from the finish. The closure further includes a resilient liner L on the inner surface of the base wall 11 that forms a primary seal when the closure is threaded on the container. The closure further comprises a cylindrical surface C on the lower end of the peripheral skirt 12 which has a diameter slightly less than the diameter of the bead 20 on the container such that when the closure is applied to the container the cylindrical surface C has an interference fit with the bead 20 on the container, thereby opposing retrograde movement of the closure in the removal direction and at the same time providing an annular seal to inhibit flow of liquid out of the container when the container is tilted. The cylindrical surface C is formed by a plurality of closely spaced annular ridges or serrations 40 separated by fine grooves 41 in alternating fashion (see Figures 2 and 4). The axial extent of the cylindrical surface C is such that the interference fit exists when the closure is fully applied to the container as well as when the closure is rotated in a retrograde fashion to the extent that the seal between the inner surface of the closure, or any liner L thereon, is broken, even though the closure has not been rotated sufficiently to disengage the tab 30 from the obstruction 23 on the container. Thus, the closure provides a secondary seal wherein a bead 20 on the container finish is positioned below the container threads and is larger in diameter than the threads; and the closure 10 has internal threads 13 to engage threads 13a on the container and a lower portion C below the threads 13a which is larger in diameter than the container threads but smaller in diameter than the container bead 20. Thus referring to Figures 8 A,B,C,D, which are schematic views of the operation of the closures shown in Figures 1-7, when the child resistant closure is applied to the container, due to dimensional variations, the tab 30 on the closure may be positioned, for example, about 90° from the tab 23 on the container. A seal exists in two locations, as shown in Figure 8A (1) at the top of the finish where a liner L in the closure contacts the top of the finish and (2) an interference fit between the apex 20 of the container finish and the interior cylindrical surface of the closure. When the closure is fully applied, the thread engagement between the closure and container is such that the lower side of the container threads will be in contact with the upper side of the closure threads, and will keep the liner L in contact with the sealing surface of the finish. As the closure is rotated in a retrograde direction of removal, the threads on the closure and container will disengage from each other, and the liner will no longer be forcefully held in contact with the sealing surface on top of the container finish as shown in Fig. 8B. However, the package will not leak because the secondary seal provided by the interference fit between the apex on the finish bead 20 and the surface C on the interior of the closure skirt will remain in the sealing position. Further, rotation of the closure in the direction of removal will cause the under side of the closure thread to contact the upper side of the container thread (Fig. 8C) and cause the closure to move axially upward with respect to the container finish. Continued rotation in the removal direction will move the closure upward until the apex of the container bead is below the skirt of the closure and the secondary seal will now be opened Fig. 8D. Finally, continued rotation will result in total disengagement between the closure and container threads and the closure being removed from the package. A relationship exists between the axial position of a closure on a finish and the number of degrees of rotation of the closure on the container from any arbitrary reference point. For example, in an ordinary screw type lined closure applied to an appropriate finish, if one were to remove the liner, it would be evident that the closure could be turned onto the container further, that is the relative axial position of the closure with respect to the inside top of the closure would change and the number of degrees of rotation in applying the closure would increase. In much the same way, dimensional tolerances of the container finish and closure will affect the relative axial position of the closure and the number of degrees of rotation required to seat the closure on the finish. The present invention is not affected by these dimensional tolerances as the length of the closure skirt, in the area contacted by the apex of the bottle bead, can be made sufficient to afford engagement over a wide range of tolerances. In the prior art United States Patent No. 3,971,478 which utilized a single seal between the closure and container, the vertical height and dimensional tolerances of the closure and container finish are critical. That is the relative vertical distance between the bead on the container finish and the internal bead on the closure is essential to insuring that the liner remain in contact with the container finish during retrograde movement. In other words, the total of all the dimensional tolerances affecting the vertical relationship between the top of the container finish and the bead on the container; plus all of the dimensional tolerances affecting the distance from the liner, where it contacts the container finish, to the bead on the closure where it contacts the finish bead, must be equal to or less than the distance from the top of the container thread to the bottom of the closure thread when the closure is fully tightened on the container finish. (Fig. 9A) This may be more readily understood by reference to Figs. 9A,B,C, and D which are schematic views similar to Figs. 8A,B,C, and D. In this prior patent, it is essential to have a zone equal to or less than the number of degrees of rotation from a fully tightened position of the closure on the container to the position where the tab 30 on the closure contacts the abutment 23 on the container. If this zone is less, as the closure is turned in retrograde, the bottom surface of the closure thread will contact the top surface of the container thread and drivingly force the closure upward so that the liner is moved out of contact with the container sealing surface, before the tab on the closure contacts the abutment on the container as shown in Fig. 9C. The closure may be molded of thermoplastic material, preferably polypropylene or polyethylene. The container is manufactured of any suitable material including plastic, glass or metal. While a lined closure is shown, this invention is not limited to lined closures and the concept could be utilized with any number of different linerless features. It can thus be seen that there has been provided a child resistant closure which is adapted to be used with a container to provide a child resistant package and which comprises a closure having a base wall and a peripheral skirt with internal threads adapted to engage complementary threads on the container. The closure is provided with a tab which is engageable with a projection on the container to prevent unthreading of the closure except when the tab is depressed. A cylindrical surface on the skirt frictionally engages an annular bead on the container to provide resistance to closure back off in order to resist unthreading of the closure from the container. The cylindrical surface comprises a series of closely spaced annular serrations and alternating fine grooves.

Claims: A package comprising a container (G) having a finish with external threads (13a) and having an annular bead (20) on the container spaced below the threads, said bead having an apex, a plastic closure having a base wall (11) and a peripheral skirt (12) with complementary internal threads (13) adapted to engage said threads (13a) on the container, a deflectable portion (21,30,35) on said closure and an abutment (23) on the container, said portion being adapted to extend into the path of the abutment on a container such that the deflectable portion can be deflected past the abutment when the closure is applied to the container but will engage the abutment when the closure is grasped and rotated to remove the closure unless the deflectable portion is manually depressed, characterised in that said skirt (12) of said closure has a cylindrical surface (C) comprising a plurality of closely spaced annular serrations (40) and fine grooves (41) separating said serrations in alternating fashion, said serrations and associated fine grooves having an axial extent such that an interference fit will exist over a wide range of tolerances of the container finish and closure with the apex of the bead when the closure is fully applied as well as when the closure is rotated in retrograde fashion to the extent that any other seal between the closure and container is broken, even though the closure has not been rotated sufficiently to disengage the deflectable portion from the abutment on the container. A package as claimed in Claim 1 wherein said deflectable portion is a tab (21) hinged intermediate its ends to the skirt (12) of the closure and extending at an angle to the circumference of the closure so that the outer end of the tab will engage the abutment (23) on the container. A package as claimed in Claim 2 wherein said closure includes a projection (24) extending radially outwardly therefrom adjacent the opposite end of the tab (21) such that when the tab engages the abutment (23) on the container, the tab becomes wedged between the abutment (23) on the container and the projection (24) on the closure. A package as claimed in Claim 1 wherein said deflectable portion is a tab (35) hinged to the closure at one end (36) and extending circumferentially in a direction opposite to the direction in which the closure is rotated to apply the closure.

Inventors: KUSZ MAXIMILLIAN, KUSZ, MAXIMILLIAN
Applicants: OWENS ILLINOIS CLOSURE INC, OWENS-ILLINOIS CLOSURE INC.,
Application year: 1991
Main classification: B65D41
IPC codes: B65D50, B65D41