A frangible closure has a closure sheet having a central weakness formed substantially though a medial portion. The central weakness has a thickness and a central portion of greater thickness than the thickness of the central weakness so as to resist shearing of the central weakness. A lateral skirt surrounding the closure has at least a partial radial weakness therebetween for cooperating with the central weakness and enabling the central weakness to fracture.

FIELD OF THE INVENTION
 The invention relates generally to the field of emptying containers or
 flasks containing specific products. More specifically, the invention
 relates to a frangible closure for containers or flasks containing
 photographic development chemicals.
 BACKGROUND OF THE INVENTION
 Certain chemical products must, prior to their use, be specially mixed with
 other products of the same nature. For shelf-life reasons or product
 freshness it is often important for the mixing to be carried out just
 before use. This is particularly the case with chemical products in
 photographic processing. Customer requirements for easier handling of
 these photochemical bottles with less exposure to the chemicals has
 generated the need for a cap which does not need to be removed or replaced
 to dispense photochemicals. Seal integrity, customer handling, and
 recyclability has generated the need for a cap molded from high density
 polyethylene (HDPE) resin which can seal the bottle and be opened simply
 by inserting the bottle into processing apparatus. At the present time,
 each product forming part of such a combination is stored in a plastic
 flask closed by a liquid tight stopper. The photochemical manufacturing
 community currently utilizes various methods for sealing bottles filled
 with photographic development chemicals which includes, but is not limited
 to: 1) foam/cardboard seal insert inside the bottle cap; and 2) aluminum
 foil seal welded over the bottle neck opening and covered with a cap. A
 shortcoming of the aforementioned sealing methods is that they each
 present a propensity to leak that detracts or prevents recycling of the
 bottle without removing the cap and seal residue.
 Another currently available practice for sealing a flask used in the
 photochemical manufacturing community includes a bottle cap with an
 integral bottleneck seal and segmented lid section. The cap provides a
 reliable fluid seal while the segmented lid is rupturable by blades
 available on existing photographic processing apparatus that tear or
 rupture the segmented portion of the cap. The aforementioned stopper
 design utilizes a tear channel or weakness with a rectangular
 cross-section to bisect half of the frangible lid.
 While the above cap meets the bottle seal requirements and recycling
 requirements, it is generally known in the photochemical community that a
 rather significant shortcoming is the puncturability of the segmented lid.
 Skilled artisans will appreciate that the downward force (average puncture
 force of 30.12 lbs. or 134.5 Newtons) required to puncture the segmented
 lid is beyond the physical capabilities of the average person.
 Therefore, a need persists in the art to remedy the aforementioned
 shortcomings by requiring lower puncture forces while maintaining an
 inexpensive emptying method, as well as complete recyclability of the
 flask and closure.
 SUMMARY OF THE INVENTION
 It is, therefore, an object of the invention to provide a frangible closure
 for a container, such as a flask for photoprocessing chemicals, which is
 recyclable, prevents leaks, and opens easily.
 It is another object of the invention to provide a frangible closure that
 collapses along a central weakness and partially along a radial weakness.
 Yet another object of the invention is to provide a frangible closure
 having at least two hinge points which enables the closure sheet to bend
 inward towards an adjoining processing container.
 It is a feature of the invention that a central weakness and a connecting
 radial weakness in the closure sheet of the frangible closure enables the
 closure to easily collapse inward toward the container to which it is
 adjoined.
 The present invention is directed to overcoming one or more of the problems
 set forth above. Briefly summarized, according to one aspect of the
 present invention, a frangible closure, comprises a closure sheet having a
 central weakness formed substantially through a medial portion of the
 closure sheet. The central weakness has a thickness and a central portion
 of greater thickness than the thickness of the central weakness so as to
 resist shearing of the central weakness. A lateral skirt surrounds the
 closure sheet. Between the lateral skirt and the closure sheet is at least
 a partial radial weakness for cooperating with the central weakness and
 enabling the central weakness to fracture in response to an applied
 predetermined force.
 The present invention has numerous advantages over current developments.
 First, the frangible closure of the current invention reduces the puncture
 forces to an acceptable level. The addition of a gate pad allows the tear
 channel to be molded through the center of the closure resulting in lower
 puncture forces while eliminating the possibility of shearing a hole
 through the top of the closure. The gate pad allows the frangible closure
 to be center gated eliminating weld lines in the cap that can crack under
 loads, allowing leakage of photographic chemicals through the cap.

DETAILED DESCRIPTION OF THE INVENTION
 Turning now to the drawings, and particularly to FIGS. 1-4, the present
 invention concerns a liquid-tight, removable, frangible closure 12 molded
 preferably from a recyclable high-density polyethylene (HDPE) material.
 According to FIG. 1, frangible closure 12 has at least one closure sheet
 14 fixed to a lateral skirt 16 enabling the closure 12 to be mounted (for
 example, by a screw), on the spout of a container or flask, described
 below. According to FIGS. 2-4, frangible closure 12 has a closure sheet 14
 having a central weakness 18 formed substantially through a medial portion
 19 of the closure sheet 14. Central weakness 18 has a thickness and a
 central portion 22 of greater thickness than the thickness of the central
 weakness 18. It is advantageous for central portion 22 of greater
 thickness to have a thickness greater than the thickness of the central
 weakness 18 so as to resist shearing of the central weakness 18 due to
 gate shear in the molding process. In the preferred embodiment of the
 invention, central weakness 18 is an inverted V-shaped channel. The
 inverted V shaped channel propagates from the central portion 22 of the
 closure sheet 14 outward towards the radial weakness (described below).
 Moreover, the inverted V-shaped channel is preferably molded through the
 medial portion 19 of the underside of the frangible closure 12. It allows
 for lower puncture forces (average puncture force of 24.27 lbs. or 108
 Newtons) to collapse the closure sheet 14, as described herein. The
 addition of the central portion 22 of greater thickness eliminates the
 possibility of shearing a hole through the closure sheet 14 during the
 injection molding process due to gate shear. Moreover, central portion 22
 of greater thickness, in the preferred embodiment, is a gate pad molded
 into the closure sheet 14 having opposed, spaced apart, substantially
 equal thickness portions 24.
 Referring to FIGS. 3 and 4, lateral skirt 16 surrounds the closure sheet
 14. The lateral skirt 16 and the closure sheet 14 have a radial weakness
 28 at least partially therebetween which cooperates with the central
 weakness 18 and enables the central weakness 18 to fracture under an
 applied force. More particularly, radial weakness 28 is a channel
 comprising spatially separated hinge points 30 for enabling the central
 weakness 18 to collapse into the radial weakness 28. More importantly, the
 hinge points 30 prevent the closure sheet 14 from separating from the
 lateral skirt 16 when the closure sheet 14 is under an applied pressure.
 Each of the preferably two hinge points 30 has a thickness greater than
 the thickness of the radial weakness 28. Moreover, hinge points 30 are
 spatially separated preferably about 180 degrees apart. Further, hinge
 points 30 are molded into the top of the frangible closure 12 normal from
 the central weakness 18 allowing the punctured closure sheet 14 to fold
 away toward the container.
 The central weakness 18 together with the radial weakness 2528, also
 referred to as frangible areas, allow the closure sheet 14 of the
 frangible closure 12 to tear under load across the medial portion 19.
 Depicted in FIGS. 2-4, frangible closure 12 may include a plurality of
 threads 32 on the interior wall 34 of lateral skirt 16 for engaging
 corresponding threads in a container or flask to which it is connected, as
 described below. The threads 32 provide a means to reduce leaks from the
 frangible closure 12 and container when the two are tightly screwed
 together. Those skilled in the art, however, will appreciate that
 frangible closure 12 may be designed to snap securely onto the container
 without the necessity of threads 32 and cooperating threads in the
 container.
 Referring to FIG. 1, lateral skirt 16 may include a plurality of outer ribs
 36 for facilitating twisting the frangible closure 12 away from the
 container body.
 Turning now to FIGS. 5-6, in another embodiment of the invention, a fluid
 transfer system 50 includes a first container 52 containing a fluid and
 second container 54 in fluid communications with the first container 52.
 First container 52 has a body 56, a neck portion 58 extending from the
 body 56 and terminating in an opening 60. A frangible, removable and
 recyclable closure 62, having all the features described hereinabove, is
 affixed to the opening 60 for closing the opening 60 and exposing the
 fluid therein to fluid communications with the second container 54 in a
 manner described above.
 Referring to FIGS. 5-6, second container 54 comprises means, such as
 perforation member 66, for applying a force to the central weakness 18
 (FIGS. 3-4) thereby collapsing the central weakness 18 into the radial
 weakness 28. This enables fluid flow from the first container 52 into the
 second container 54.
 Referring to FIG. 5, in operations, the emptying of a first container 52
 having the frangible closure 62 of the invention is effected by tipping
 over first container 52 onto a perforation member 66 disposed inside an
 emptying orifice (not shown) of second container 54. The emptying is
 effected directly through the closure sheet 14 of the frangible closure 12
 held in the closed position on the spout of the first container 52. The
 central weakness 18 is punctured by the force of the perforation member 66
 that causes a portion of the closure sheet 14 to collapse along the
 central weakness 18 inwardly towards the first container 52. This
 puncturing action creates a flow path inside the first container 52 that
 enables the fluid to flow from the first container 52 into the second
 container 54.
 The invention has been described with reference to a preferred embodiment.
 It will, however, be appreciated that variations and modifications can be
 effected by a person of ordinary skill in the art without departing from
 the scope of the invention.
 TS LIST
 12 frangible closure
 14 closure sheet
 16 lateral skirt
 18 central weakness of closure sheet 14
 19 medial portion of closure sheet
 22 central portion of closure sheet 14
 24 opposed thickness portions
 28 radial weakness
 30 hinge points
 32 threads
 34 interior wall of lateral skirt 16
 36 outer ribs
 50 fluid transfer system
 52 first container
 54 second container
 56 body of first container 52
 58 neck portion of first container 52
 60 opening
 62 alternative embodiment of recyclable closure
 66 perforation member