Dispenser and process

Information

  • Patent Grant
  • 6641319
  • Patent Number
    6,641,319
  • Date Filed
    Thursday, October 4, 2001
    23 years ago
  • Date Issued
    Tuesday, November 4, 2003
    21 years ago
Abstract
A dispenser (10) for use in dispensing liquid or solid material. The dispenser (10) includes wall portions forming a sealed first chamber (18) containing the material and wall portions forming a second chamber (20) and a molded, rupturable membrane (34) disposed between the first chamber (18) and the second chamber (20). The rupturable membrane (34) is preferably a circular disk with a series of molded radial depressions (40) or weld seams (40) extending from a center point of the disk. When pressure is applied directly to the membrane (34), the membrane (34) is fractured along the depressions (40) or weld seams (40). A method is provided for forming the dispenser (10) by injection molding.
Description




DESCRIPTION




1. Technical Field




The invention generally relates to a dispenser for a flowable substance and, in particular, the invention relates to a one piece fluid dispenser having two chambers separated by a membrane.




2. Background of the Invention




Different types of containers and dispensers for the distribution of material are known within the packaging industry. One example is described in U.S. Pat. No. 3,759,259 issued Sep. 18, 1973 to Andrew Truhan. The Truhan patent discloses a combination applicator and container for medicinal substances. The applicator includes a holder and a fibrous wadding of cotton. The container has flexible walls and a flat seal that spans the container opening. The flat seal is heat sealed to the interior surface of the container. The flat seal is perpendicular to the flexible walls and ruptures upon the application of inward force to the container side walls. In another embodiment, the flat seal includes one or more score lines which form lines of weakness or burst lines when an inward force F is applied to the container side walls.




U.S. Pat. No. 3,684,136 to Baumann discloses a receptacle for receiving and mixing liquid and/or solid substances. The receptacle includes a lower mixing chamber M, an upper secondary chamber S, and a foil dividing wall. The lower surface of dividing wall is convex and the top surface of the wall is concave. In the first embodiment, the surface of the dividing wall features a scored notch(es), that signifies a weakened portion of the dividing wall. The notches can be arranged in a star or cross orientation. To tear the dividing wall, lateral pressure P is applied to receptacle walls adjacent to the dividing wall. When lateral pressure P is terminated, the dividing wall returns to its original shape and the opening will close. In the second embodiment, the receptacle includes outer projections which indicate the direction in which the notches should be disposed during assembly.




In both Truhan and Baumann, the seal separating the chambers has score lines which are formed from the removal of material from the seal itself. The removal of material is necessary to sufficiently weaken the seal structure to facilitate rupture. However, the removal of material compromises the burst strength of the seal and can lead to inconsistent and untimely seal rupture. As a result, the effectiveness of both the seal and the device is reduced.




Furthermore, with both devices it is necessary to under fill the container with liquid leaving ample air space. This under filling increases the chance of accidental seal rupture from pressure on the container. Consequently, the volume of liquid stored within the chamber must be reduced.




Lastly, the dispensers disclosed in Truhan and Baumann are designed to release the entire fluid contents at one time. Thus, the user cannot control the distribution and application of the liquid over a period of time.




The present invention is provided to solve these and other problems.




SUMMARY OF THE INVENTION




The present invention provides a dispenser for discharging either a liquid or solid material. To this end, there is a device provided having two adjacent chambers separated from each other by a novel rupturable web or fracturable membrane. The first chamber has a distal end and is a storage chamber for the material. The second chamber has a proximate end and receives the material when released from the first chamber by rupture of the membrane. The first and second chambers are defined by a peripheral wall with an elongated axis forming a sleeve or cylinder. After the material is added to the first chamber, the distal end, the end opposite from the membrane, is sealed to hold the material in the first chamber. The first chamber can be closed off or sealed by pressing the sides of the end of the chamber together and heat sealing or applying an adhesive. Alternatively, the first chamber can be sealed by applying a cap over the end of the tube. The membrane separating the chambers is provided with a weld seam and is broken by lateral force on the membrane to allow the fluid to flow from the first chamber into the second chamber. The thickness of the membrane can be varied, thereby either increasing or decreasing the amount of applied force needed to rupture the membrane.




In accordance with the invention, the web is preferably disk-shaped having a series of radial disposed uniform depressions on one surface of the disk and extending from a center point of the disk in the form, for example, of spokes on a wheel. The thickness of the disk is lesser at the depressions. When the disk is compressed by exerting pressure on the edge of the disk, the web breaks along the depressions forming a series of finger-like triangular projections extending from the face of the disk. Since the fingers are widest where they contact the container wall, the center section of the disk preferably opens first to material flow. The amount of material that can pass into the second chamber is controlled by the degree of opening which corresponds to the depressed areas and the pressure applied to the chamber. In a preferred embodiment, the depressed areas are formed on only one side of the disk but could also have depressed areas on both sides of the disk. The fingers formed as a result of the compression will extend in the direction of the flow of the material. This arrangement permits an even flow of the material.




According to another aspect of the invention, the novel membrane has opposing first and second surfaces and contains a weld seam. The membrane is formed by a first segment of injected molded material that abuts a second segment of injected molded material to form the weld seam. The segments abut at an interface area. The membrane thickness is reduced at the weld seams. In one preferred embodiment, the weld seam comprises a plurality of weld seams that are generally pie-shaped and are molded at right angles to the interior surface of the dispenser. The mold segments are widest at their base where they extend from the interior dispenser surface and narrow as they radially extend toward a center portion of the membrane.




Under normal use and operation, the membrane partitioning the first and second chambers can only be ruptured by the precise administration of force on the membrane. The membrane will not rupture when the first chamber is compressed by normal hand pressure. Conversely, extreme force loads are required to rupture the membrane by compressing the first chamber. Such forces would not be present during normal use and handling of the dispenser.




When the membrane is compressed by exerting pressure on the edge of the membrane, the membrane ruptures only along the weld seams. Unlike prior art devices, the membrane rupture is predictable and controlled at the weld seams. The amount of material which can pass into the second chamber is controlled by the degree of membrane opening which is directly controlled by the amount of force applied to the membrane by the user.




According to another aspect of the invention, the outer surface of the chamber walls can be provided with a marking to indicate the preferred location where force should be applied to rupture the membrane. In one preferred embodiment, the marking is an external extension. Such an extension can be in the form of a thumb pad, which corresponds to the location where force should be applied. Alternately, the outer surface of the chamber can have any type of raised area or projection such as a circular band around the outside of the chamber to indicate the desired point of force application. The outer surface could also have an indicia or other marking to indicate where force should preferably be applied.




In accordance with the invention the dispenser is produced in a unitary configuration by a molding process. The mold has a cavity formed to correspond to the outer surface of the chambers. Two laterally opposed pistons, or core pins, are extended into the mold cavity to form the inner surface of the chambers. An end of one of the pistons is configured with a raised structure that facilitates the formation of weld seams, or depressions on the membrane. The membrane structure can be in many configurations, including but not limited to a cross or star.




The molding process is initiated by the injection of thermoplastic material into the cavity. Once injection is complete, the mold is then cooled by circulating a cooling medium, such as water, in a cavity surrounding the mold. The core pins are then retracted to allow release of the molded product.




The flowable material to be utilized can be fed into the first chamber and the end of the chamber sealed. Because the release of the material depends on the application of pressure to the web to break the weld lines, and not the pressure of the material fluid against the web, it allows the chamber to be filled with small quantities of material. If the seal is to be broken by the pressure of liquid material as in the prior art devices, sufficient liquid has to be present to create the required hydraulic pressure when compressed. Further, the dispenser of the invention allows the dispensing of non-liquids such as a powder which would not exert any hydraulic pressure.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective view of a dispenser according to the present invention;





FIG. 2

is a top plan view of the dispenser of

FIG. 1

prior to sealing a distal end of the dispenser;





FIG. 3

is a cross-sectional view of the dispenser taken along lines


3





3


in

FIG. 2

;





FIG. 4

is an enlarged partial cross-sectional view of a membrane taken from

FIG. 3

;





FIG. 5

is another enlarged partial cross-sectional view of the membrane;





FIG. 6

is an end view of the dispenser facing into a first chamber;





FIG. 7

is a cross-sectional view of a weld line taken along lines


7





7


of

FIG. 6

;





FIG. 8

is an end view of the dispenser facing into the second chamber;





FIG. 9

is an elevational view of the membrane having forces applied thereto wherein the membrane is fractured along weld lines;





FIG. 10

is partial elevational view of the dispenser supporting a swab;





FIG. 11

is a partial elevational view of the dispenser supporting a dropper;





FIG. 12

is a partial perspective view of a core pin having an end face with a raised structure;





FIG. 13

is a cross-sectional view of a mold and a portion of the material for forming the dispenser;





FIGS. 14



a


-


14




f


are a series of views showing the injection molding process of the membrane wherein adjacent mold segments abut to form weld lines;





FIG. 15

is a schematic view of the dispenser supporting in a filling apparatus; and





FIG. 16

is a schematic view of a sealing apparatus for sealing the material into the dispenser.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT




While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.




Referring to the drawings,

FIG. 1

discloses a dispenser according to the present invention generally designated by the reference numeral


10


.

FIGS. 2 and 3

show the container


12


prior to having one end sealed as will be described in greater detail below. As shown in

FIGS. 2 and 3

, the dispenser


10


generally comprises a container


12


with an elongate axis L having a peripheral wall


16


. In one preferred embodiment, the container


12


is cylindrical. However, the container


12


can be molded in numerous shapes, including an elliptical shape.




As further shown in

FIGS. 2 and 3

, the container


12


generally comprises a first chamber


18


and a second chamber


20


separated by a web or membrane


34


described in greater detail below. While a two chamber dispenser is one preferred embodiment, more or less chambers can also be defined within the container


12


. The first chamber


18


, which is adapted to contain the material to be dispensed, has an interior surface


22


, an exterior surface


24


, and a distal end


26


. The second chamber


20


has an interior surface


28


, an exterior surface


29


, and a proximate end


30


. An end portion


32


is located on the exterior surface


24


of the first chamber


18


at the distal end


26


. As explained in greater detail below, the distal end


26


of the first chamber


18


can be closed by a number of sealing methods, including heat or adhesive sealing. Alternatively, the distal end


26


can receive a cap to close the first chamber


18


. When the distal end


26


is sealed, and in cooperation with the membrane


34


, the first chamber


18


is a closed chamber for holding a flowable material such as a liquid medicinal fluid. As also shown in

FIG. 3

, if desired, the cylinder


12


can be necked down wherein the second chamber


20


has a smaller diameter than the diameter of the first chamber


18


.




As shown in

FIGS. 3-7

, the web


34


is preferably constructed in the form of a disk


35


. The disk is preferably a flat plastic sheet having a series of radial depressions


40


on a first surface


36


of the web


34


. The radial depressions


40


extend from substantially a center point


33


of the web


34


to an outer edge


37


of the disk, for example, in the form of spokes of a wheel. Compression of the cylinder, such as by finger pressure, causes the web


34


to break, or rupture, only along the radial depressions


40


forming a series of finger-like projections


39


which are displaced in overlapping fashion (

FIG. 9

) to create web openings


41


for release of the material from the first chamber


18


to the second chamber


20


. Since the projections


39


are “pie-shaped” and widest at their outer edges


37


, the center section of the web


34


breaks open the widest. The amount of material that can be dispensed through the web


34


is controlled by the degree of the opening


41


. The size of the opening


41


is controlled by the configuration of the depressions


40


and the pressure of the fingers of the user pressing on the container


12


to assert pressure on the web


34


.




As further shown in

FIGS. 3-7

, the web


34


or membrane


34


partitions the container


12


to separate and, therefore, define the first chamber


18


and the second chamber


20


. Although

FIG. 3

shows the membrane


34


closer to the proximate end


30


than the distal end


26


, the placement of the membrane


34


is a function of the desired volume capacity of the second chamber


20


. As such, the membrane


34


could be located at numerous locations in the cylinder


12


.




As shown in

FIGS. 3 and 4

, the membrane


34


has a first surface


36


and a second surface


38


. The first surface


36


faces towards the first chamber


18


, while the second surface


38


faces towards with the second chamber


20


. The second surface


38


is substantially planar. The first surface


36


, however, has a plurality of bands or mold seams


40


thereon. Also in a preferred embodiment, the membrane


34


is disposed substantially transverse to the elongated axis L of the container


12


. As will be described in greater detail below, and as generally shown in

FIGS. 5-6

, and


13


-


14


, a first segment


60


of injected molded material abuts a second segment


62


of injected molded material to form the weld seam


40


. As can be further seen in

FIG. 5

, the membrane


34


has a base thickness “t


1


” between the first membrane surface


36


and the second membrane surface


38


. The thickness t


1


is generally referred to as the membrane thickness. The weld seam


40


has a thickness t


2


that is less than the membrane thickness t


1


. This facilitates rupture of the membrane


34


as described below. The first mold segment


60


and the second mold segment


62


abut to form the weld seam


40


. During the molding process, the mold segments


62


,


64


move toward the interface area


64


in the directions of arrows A. Furthermore, the mold segments


60


,


62


meet substantially at the interface area


64


at the lesser thickness t


2


. This forms the weld seam


40


at the lesser thickness facilitating rupture of the membrane


34


. If the mold segments


60


,


62


did not meet at the interface area


64


but, for example, substantially further to either side of the interface area


64


, the weld seam


40


would be too thick and not be able to rupture. Whichever mold segment


60


,


62


moved past the interface area


64


, the segment would merely flex and not rupture as desired. Thus, as described below, the molding process in controlled to insure that the mold segments abut substantially at the interface area


64


to form the weld seam


40


having a thickness t


2


less than the membrane thickness t


1


.




As shown in

FIG. 6

, the membrane


34


preferably contains a plurality of weld seams


40


, which can be arranged in a number of configurations including but not limited to a cross, star, or asterisk. It is understood, however, that the benefits of the invention can be realized with a single weld seam


40


formed from a pair of mold segments abutting one another. In a preferred embodiment, the weld seams


40


are arranged in a asterisk configuration wherein the membrane has a pie-shape. Adjacent mold segments


60


,


62


abut with one another to form the weld seams


40


. Due to the configuration of the mold to be described below, the weld seams


40


are formed to have a lesser thickness t


2


than the membrane thickness t


1


. As further shown in

FIG. 6

, the plurality of weld seams


40


extend radially from substantially a center point


37


on the membrane


34


completely to an outer edge of the membrane


34


and to the interior surface of the container


12


. It is understood, however, that the weld seams


40


do not need to extend to the outer edge of the membrane


34


. In a most preferred embodiment, the membrane


34


has eight mold segments, or four pairs of mold segments


60


,


62


. The eight mold segments cooperate wherein adjacent mold segments abut at eight separate interface areas


64


to form eight weld seams


40


. As shown in

FIG. 14

, the process is controlled such that the adjacent mold segments each meet at the separate interface areas


64


. Each weld seam


40


has a thickness less than the thicknesses of the segments. The thicknesses of the mold segments are considered to be the membrane thickness t


1


.




Explained somewhat differently, the first surface


36


of the membrane


34


has a channel


66


formed therein. The mold seam


40


confronts the channel


66


. The channel is formed by a first wall


68


adjoining a second wall


70


. In a preferred embodiment, the first wall


68


adjoins the second wall


70


at substantially a 90 degree angle. Acute angles or obtuse angles are also possible. Thus, in one preferred embodiment, the channels are V-shaped.




As shown in

FIGS. 1-3

, the exterior surface


28


of the container


12


has an exterior extension


46


to indicate the exact location where force should be applied to rupture the membrane


34


. Specifically, the extension


46


is located directly adjacent to the membrane


34


. Although the extension


46


is shown as a thumb pad with a plurality of ridges


47


, any type of raised area or projection including a button, prong or ring will suffice. In addition, a ring of material could be applied around the perimeter of the container


12


corresponding to the location of the web


34


so that a user would know precisely where to apply finger pressure. An indicia-bearing marking would also be sufficient.




As shown in

FIGS. 8 and 10

, the interior surface


28


of the second chamber


20


has a plurality of longitudinal ribs


48


. The ribs


48


are oriented axially in the second chamber


20


and can be of varying length. The ribs


48


could be shortened and extend radially inwardly. The ribs


48


secure different applicators, such as a swab (FIG.


10


), which can be used to apply the dispensed liquid or solid material. The swab forms an interference fit with the ribs


48


.




In a preferred embodiment, the dispenser


10


is made of a transparent, flexible thermoplastic material. The preferred plastic material is polyethylene or polypropylene but a number of other plastic materials can be used. For example, low-density polyethylene, polyvinyl chloride or nylon copolymers can be used. In a preferred embodiment, a mixture of polypropylene and polyethylene copolymer or thermoplastic olefin elastomer is used. In another preferred embodiment, a mixture of polypropylene and Flexomer®, available from Union Carbide, is utilized. It is essential that the dispenser be made of material which is flexible enough to allow sufficient force to rupture the membrane


34


.




As shown in

FIG. 9

, in operation, a user applies a selective force F on the dispenser


10


at the exterior extension


46


adjacent to the membrane


34


. When sufficient force is applied, lateral pressure is applied to the membrane


34


causing the membrane


34


to shear and rupture along the weld seams


40


. The membrane


34


ruptures only along the mold seams


40


to create membrane openings


41


. Upon rupture of the membrane


34


, material passes from the first chamber


18


through the membrane


34


and into the second chamber


20


. The material flow rate through the membrane


34


and into the second chamber


20


is controlled by the degree of membrane


34


opening which is directly related to the amount of force applied to the membrane


34


by the user. Therefore, the user can precisely regulate the flow of material after rupture of the membrane


34


. In addition, the membrane


34


can preferably have elastic characteristics wherein when force is removed, the membrane


34


returns substantially to its original position. While the mold seams


40


may be ruptured, the segments


60


,


62


can form a close enough fit to prevent material from flowing past the membrane


34


without additional pressure on the material. Thus, the membrane


34


can act as a check valve to prevent unwanted discharge of the material.





FIG. 10

shows another embodiment of the dispenser of the present invention. Like elements will be referred to with identical reference numerals. The dispenser


10


has a first chamber


18


and a second chamber


20


separated by a membrane


34


. The first chamber


18


has a closed end wall


25


enclosing material M. The second chamber


20


receives an applicator or swab


49


. The swab


49


engages the inner surface


28


of the second chamber


20


and in particular the longitudinal ribs


48


to form an interference fit. Once the membrane


34


is fractured as described, the swab


49


receives and absorbs the material M as it is dispensed from the first chamber


18


and into the second chamber


20


. The swab


49


has a contact surface


49




a


that is used to dab a desired area such as a skin surface having an insect bite. The dispenser


10


can be inverted and squeezed until the swab surface


49




a


is wet. The dispenser


10


can then be held in a vertical position with the swab


49


pointed upwardly. Alternatively, the swab


49


can be made of a material of relatively large porosity for passing droplets through the swab


49


by gravity and for dispensing droplets from its exterior surface. The swab


49


can be made of polyester, laminated foamed plastic, cotton or the like.





FIG. 11

shows the dispenser


10


having a dropper attachment. The second chamber


20


has a dropper


50


. The dropper has an elongate spout


52


with a passageway


54


for dispensing droplets of the material M. The dropper


50


has a cup-like portion


56


that overlaps a portion of the outer surface


29


of the second chamber


20


. Once the membrane


34


is ruptured as described and material M passes from the first chamber


18


to the second chamber


20


, droplets of the material M can be dispensed through the spout


52


.




The preferred dispenser


10


has a length of about 1.5 to about 3.0 inches, although larger containers can be utilized, with 2 to about 2.5 inches being preferred. The outside diameter of the container is about 0.30 to about 1.0 inches.




The wall thickness is about 0.018 to about 0.035 inches and preferably about 0.022 inches. The first chamber


18


is preferably from about 1.30 to about 2.7 inches. The exterior extension


46


is preferably about 0.10 to about 0.50 inches in width and about 0.010 to 0.125 inches thick. The second chamber


20


is preferably about 0.20 to about 1.5 inches and preferably 0.75 inches in length. The membrane


34


preferably has a thickness of about 0.02 to about 0.0625 inches. The mold seams


40


have a preferable thickness of about 0.003 to about 0.008 inches and preferably about 0.005 inches. The above dimensions can be varied depending upon overall dispenser size.




In another preferred embodiment, the membrane


34


forms eight narrow spokes of substantially uniform width extending from the center of the membrane


34


to the inner wall of the container


12


. Each spoke extends at a 45 degree angle from the adjacent spokes on either side.




The method of making the dispenser


10


is generally illustrated in

FIGS. 12-16

. The dispenser


10


is produced in a single molding operation thus providing a one-piece injected-molded part. As shown in

FIG. 13

, a mold


80


is provided having a mold cavity


82


therein. The mold cavity


82


is dimensioned to correspond to the exterior surface of the dispenser


10


. A first core pin


84


and a second core pin


86


are provided. The core pins


84


,


86


are dimensioned to correspond to the interior surface of the dispenser


10


. The second core pin


86


has a generally planar end face


100


.




As shown in

FIG. 12

, the first core pin


84


has an end face


88


having a raised structure


90


thereon. The raised structure


90


is in the form of a ridge


92


. The ridge


92


is what provides the depressions or weld seams


40


at the certain thickness in the membrane


34


. In a preferred embodiment, the ridge has a first wall


94


adjoining a second wall


96


to form a line


98


. Furthermore, in a preferred embodiment, the ridge


92


comprises a plurality of ridges radially extending from a center point of the end face. The ridges define a plurality of membrane segments, or mold gaps


93


, between the ridges


92


. Thus, it can be understood that the raised structure


90


in the form of the ridges


92


provides the corresponding structure of the membrane


34


. Although shown as triangular, the ridges


92


can be formed in a number of shapes, including square or rounded. In addition, the ridges


92


can be arrayed in a multitude of shapes, including a single line, a cross, a star, or an asterisk. Varying the shape of the ridges


92


will affect the shape of the channels


66


. The first core pin


84


can be cylindrical but in another preferred embodiment, it can be elliptical.




The first core pin


84


is inserted into the mold


80


with the raised structure


90


facing into the mold cavity


82


. A first space


104


is maintained between the mold


80


and the length of the first core pin


84


. The second core pin


86


is also inserted into the mold cavity


82


wherein a second space


106


is maintained between the mold


80


and the second core pin


86


. The core pins


84


,


86


are generally axially aligned wherein the end face


88


of the first core pin


84


confronts the end face


100


of the second core pin


86


in spaced relation. Thus, a membrane space


108


is defined between the end faces


88


,


100


of the core pins


84


,


86


. End plates


110


,


112


are installed on end portions of the mold


80


to completely close the mold. An exterior extension cavity


117


is located on the surface of the mold


80


and adjacent to the membrane space


108


.




Molten thermoplastic material is injected into the mold cavity


82


through an inlet


114


. The material flows into the first space


104


, second space


106


and membrane space


108


. The plastic injection is controlled such that the plastic enters the membrane space


108


simultaneously in the circumferential direction. The raised structure


90


separates the material into separate mold segments


60


,


62


that flow into the mold gaps. As shown in

FIGS. 13 and 14

, the mold segments


60


,


62


flow first into the wider portions of the mold gaps as this is the area of least resistance. The material continues to flow into the membrane space and then the adjacent mold segments


60


,


62


abut at the interface area


64


to form the weld seams


40


. As can be appreciated from

FIG. 13

, the mold seams


40


have a lesser thickness than the membrane thickness. During this process, air is vented from the mold cavity


82


as is conventional.




Once the plastic injection is complete, the material is allowed to cool. A cold water cooling system


116


could be utilized wherein cold water is pumped into the mold


80


outside of the cavity


82


if desired. Once cooled, the dispenser


10


can be removed from the mold


80


.




As shown in

FIG. 15

, the dispenser


10


can be passed on to a filling apparatus


120


. The dispenser


10


is then filled with a flowable material M. As shown in

FIG. 16

, the distal end


26


of the dispenser


10


is sealed by sealing dies


130


. The excess end portion


32


can then be cut-off and discarded.




Thus, a one-piece injection molded dispenser is provided. The one-piece construction provides a more repeatable part and at greater manufacturing efficiency than providing a separate piece that is secured into a container. If desired, however, the membrane could be separately molded and affixed into a container. A one-piece molding process, however, is preferred. In addition, because the membrane is molded to have the weld seams, radial depressions, or bands, an additional manufacturing step such as scoring is unnecessary. This allows the manufacture of dispensers having relatively small diameters since there is no need to allow sufficient clearance for a scoring tool. In such small configurations, it is difficult to control the scoring operation. By forming the depressions by injection molded, the desired thicknesses can be closely controlled. The membrane also resists rupture from hydraulic pressure while being easily rupturable when forces are applied to the membrane. Also, the construction of the membrane allows for the precise control of material to be dispensed by controlling the amount of force on the membrane. It is further understood that the depressions or channels could be formed on both sides of the membrane if desired. In such configuration, however, the ability of the membrane to also function as a check valve is lessened. In a preferred embodiment, however, the membrane has the depressions molded on only one side. It is further understood while certain dimensions are preferred for certain embodiments, dispensers of all sizes having similar relative dimensions can be formed according to the present invention.




While the invention has been described in its preferred embodiments, it is to be understood that the words which have been used are words of description rather than limitation and that changes may be made within the purview of the appended claims without departing from the true scope and spirit of the invention in its broader aspects. As an illustration, although the applicator has been described as being utilized for mechanical uses, it can similarly be used for applying adhesives, mastic or the like.



Claims
  • 1. A one-piece injection molded dispenser for dispensing a flowable material, the dispenser comprising:a container having a first chamber and a second chamber, the first chamber adapted to contain the material; a membrane disposed within the container separating the first chamber and the second chamber, the membrane having a thickness and a weld seam, the weld seam having a thickness less than the thicknesses of the membrane.
  • 2. The dispenser of claim 1 wherein pressure applied to the membrane causes fractionation along the weld seam wherein the material is adapted to be dispensed from the first chamber into the second chamber.
  • 3. The dispenser of claim 2 wherein after the membrane is fractured, the membrane returns to a substantially closed position when pressure is removed from the container wherein the material does not pass from the first chamber to the second chamber.
  • 4. The dispenser of claim 1 wherein the membrane has a plurality of weld seams.
  • 5. The dispenser of claim 4 wherein the plurality of weld seams extend radially from substantially a center point of the membrane.
  • 6. The dispenser of claim 1 wherein the membrane has eight weld seams, each weld seam having a thickness less than the thicknesses of the membrane.
  • 7. The dispenser of claim 1 wherein the container has an elongated axis and the membrane is disposed substantially transverse to the elongated axis.
  • 8. The dispenser of claim 1 wherein the weld seam confronts a channel formed in the membrane.
  • 9. The dispenser of claim 8 wherein a first segment of injected molded material abuts a second segment of injected molded material to form the weld seam.
  • 10. The dispenser of claim 1 wherein the membrane is a thermoplastic material.
  • 11. The dispenser of claim 1 wherein the membrane is a mixture of polypropylene and elastomer.
  • 12. A one-piece injected molded dispenser for dispensing a flowable material, the dispenser comprising:a container having a chamber adapted to contain the material; a membrane disposed at an end of the container enclosing the material within the container, the membrane having a thickness and a weld seam, the weld seam having a thickness less than the thicknesses of the membrane.
  • 13. A one-piece injection molded dispenser for dispensing a flowable material, the dispenser comprising:a container having a first chamber and a second chamber, the first chamber adapted to contain the flowable material; a membrane disposed within the container separating the first chamber and the second chamber, the membrane having a weld seam wherein a first segment of injected material abuts a second segment of injected material to form the weld seam.
  • 14. The dispenser of claim 13 wherein the weld seam has a thickness less than a thicknesses of the membrane.
  • 15. The dispenser of claim 13 wherein no material is removed from the membrane to form the weld seam.
  • 16. The dispenser of claim 13 wherein the membrane is formed while the weld seam is formed.
  • 17. A one-piece injection molded dispenser for dispensing a flowable material, the dispenser comprising:a container having a first chamber and a second chamber, the first chamber adapted to contain the flowable material; a membrane disposed within the container separating the first chamber and the second chamber, the membrane having at thickness and a weld seam, the weld seam having a substantially uniform thickness that is less than the thickness of the membrane.
  • 18. A one-piece injection molded dispenser for dispensing a flowable material, the dispenser comprising a container having a first chamber and a second chamber, the first chamber adapted to contain the flowable material; and, a membrane disposed within the container separating the first chamber and the second chamber, the membrane having at least one weld seam, the weld seam formed from a first membrane segment abutting a second membrane segment during the injection molding.
  • 19. The dispenser of claim 18 wherein the formation of the weld seam does not require the removal of material from the membrane.
  • 20. The dispenser of claim 18 wherein the membrane has a thickness and wherein the weld seam is formed during the injection molding with a thickness less than the membrane thickness.
RELATED APPLICATIONS

This is a continuation of copending application Ser. No. 09/459,704, filed Dec. 13, 1999, now U.S. Pat. No. 6,379,069 which is a Continuation-in-Part of application Ser. No. 08/790,222, filed Feb. 3, 1999, abandoned which is a Continuation-in-Part of application Ser. No. 08/354,487, filed Dec. 12, 1994 abandoned which patent applications are incorporated herein by reference and made a part hereof, and upon which a claim of priority is based.

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Continuations (1)
Number Date Country
Parent 09/459704 Dec 1999 US
Child 09/970970 US
Continuation in Parts (2)
Number Date Country
Parent 08/790222 Feb 1997 US
Child 09/459704 US
Parent 08/354487 Dec 1994 US
Child 08/790222 US