# Patent

## Title
Dispenser for medicaments and method and apparatus for making same

## Abstract

A dispenser assembly for liquid products is disclosed. Such an assembly may include an elongated barrel, and an elongated plunger having a flexible sealing lip disposed at an end thereof. The sealing lip may have an outer diameter in a relaxed state that is greater than an internal cross-sectional diameter of the barrel. When the plunger and barrel are actuated axially relative to one another, the sealing lip flexes inwardly and provides the sole contact between the plunger and the barrel.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a division of U.S. patent application Ser. No. 11/328,121, filed Jan. 10, 2006 now U.S. Pat. No. 7,438,552, which is a division of U.S. patent application Ser. No. 10/407,360, filed Apr. 4, 2003 now U.S. Pat. No. 7,070,581, which claims benefit of provisional U.S. patent application No. 60/370,203 filed Apr. 5, 2002. The disclosures of each of the foregoing patent applications are incorporated herein by reference.


FIELD OF THE INVENTION
The present invention relates to dispenser assemblies for dispensing liquid products and in particular to dispensers of the type useful in administering medicaments, such as liquid aspirin to children and to a method and apparatus for making a plunger part of the dispenser.
BACKGROUND OF THE INVENTION
The prior art as exemplified by the patents listed below show syringe assemblies for dispensing injectable medicaments which generally comprise an elongated, hollow barrel having luer-type fitting at the discharge end to mount a needle or cannula and a plunger rod which mounts a plunger usually made of rubber has radially outwardly projecting lugs or ribs which engage the barrel interior side wall during activation of the plunger rod axially in the barrel during filling of the syringe or activation of the plunger in an injection cycle. Even though these syringes are generally suitable for the purposes, it is been found that in some instances they are relatively expensive to manufacture by reason of the tolerances required to obtain the desired seal between the plunger ribs and the barrel and to prevent bypass or leakage of the medication during an injection stroke and the desired easy movement of the plunger when activating the same. It has been found that even where tolerances are controlled, leakage and ease of activation of the plunger are problematic.
REFERENCE PATENTS
BRAITHWAITE TITLE: SYRINGES U.S. Pat. No. 5,066,280 DATE OF PATENT: Nov. 19, 1991 LINNEBJERG TITLE: PRELOADABLE SYRINGE FOR AUTOMATED DISPENSING DEVICE U.S. Pat. No. 5,928,202 DATE OF PATENT: Jul. 27, 1999 DEDOLA et al. TITLE: SYRINGES AND PLUNGERS FOR USE THEREIN U.S. Pat. No. 6,224,577 DATE OF PATENT: May 1, 2001 STEVENS et al. TITLE: SYRINGE PLUNGER TIP U.S. Pat. No. 5,735,825 DATE OF PATENT: Apr. 7, 1998 SOMERS TITLE: SAFETY SYRINGE U.S. Pat. No. 6,342,045 DATE OF PATENT: Jan. 29, 2002 KOLBERG et al. TITLE: PREFILLED, STERILIZED SYRINGE WITH A NEW AND IMPROVED PLUG U.S. Pat. No. 6,142,977 DATE OF PATENT: Nov. 7, 2000 DURANZAMPA et al. TITLE: AUTO-NON-REUSABLE SYRINGE-NEEDLE SYSTEM FOR INJECTIONS FOR A UNIQUE USE U.S. Pat. No. 5,034,002 DATE OF PATENT: Jul. 23, 1991 GROSS TITLE: LOW FRICTION SYRINGE U.S. Pat. No. 5,397,313 DATE OF PATENT: Mar. 14, 1995.
SUMMARY OF THE INVENTION
With the foregoing in mind, it is an object of the present invention to provide an oral dose dispenser for use in administering medicaments, such as liquid aspirin to children which is characterized by novel features of construction and arrangement providing an effective seal between the plunger and the barrel and is easy to activate when filling and administering medicaments and which can be manufactured by a unique molding process easily and economically. In a preferred embodiment of the invention, the plunger may have a unique and distinctive tip configuration including a circumferentially extending axially directed sealing or wiper lip, which may project outwardly at a predetermined lead angle (e.g., approximately ten degrees (10°)) to the axis of hollow tubular plunger in the relaxed state. By this construction, the sealing or wiper lip may provide essentially a circumferentially extending single point of contact with the barrel bore surface and thus, the present invention combines the advantages of the prior art rubber and plastic plungers since it is economical to manufacture and functions properly over a wider tolerance range. In other words, the plunger-barrel design of the present invention may have the desired “feel” for ease of actuation over a wide range of tolerances. The plunger may easily ride in the barrel and ensure a clean and in depth dispensing of the product through the discharge tip in the barrel.
In a preferred embodiment, the plunger and barrel may be made of dissimilar materials to provide greater lubricity between the plunger and the barrel, which may contribute to easy movement and prevent galling. The barrel may be made of a clear plastic, such as polypropylene. The plunger may made of a high-density polyethylene, and may be of an opaque color so that the contrast provided by the sealing lip arrangement and the plunger tip makes it easy for the user to determine the fill height when filling the dispenser as explained in more detail hereafter. Typically, these assemblies comprising a rubber plunger and a plastic or glass barrel are not tolerance sensitive since an external lubricant is usually applied to the plunger to facilitate relatively easy movement of the plunger in the barrel. With these plural-part assemblies, however, the plunger can easily disassemble from the plunger rod and present a choking hazard to a child. Plastic plungers are also known and are less expensive to manufacture but generally present tolerance problems. For example, it has been found that small tolerance variations from one assembly to the next can make a large change in how smoothly the plunger rides in the barrel when activated.
Further as explained, the molding process of the present invention is greatly simplified because only mold components which act in two directions are required to form the plunger configuration with the flexible axially extending sealing lip. The prior art does not disclose a plunger and barrel combination where the plunger and barrel are essentially elongated, hollow tubular members and the plunger has a sealing lip formed integrally therewith providing the only contact element with the barrel during activation to fill or discharge liquid products, such as medicaments.



BRIEF DESCRIPTION OF THE DRAWINGS
These and other objects of the present invention and various features and details of the operation and construction thereof are hereinafter more fully set forth with reference to the accompanying drawings wherein:
FIG. 1 is a perspective view of a plunger and barrel of an oral dispensing assembly in accordance with the present invention particularly adapted for administering medicaments to children;
FIG. 2 is an enlarged fragmentary sectional view taken on lines 2—2 of FIG. 1 showing the plunger tip configuration;
FIG. 3A is a transverse sectional view of the plunger and barrel assembled;
FIG. 3B is an enlarged sectional view showing the sealing lip engaging the inside of the barrel;
FIG. 4A is a transverse sectional view similar to FIG. 3A showing the plunger at the upper end of its retract stroke;
FIG. 4B is an enlarged fragmentary sectional view of the portion circled in FIG. 4A and identified by numeral 4B;
FIG. 5A is a transverse sectional view showing the plunger fully bottomed out and the contents completely dispensed;
FIG. 5B is an enlarged fragmentary sectional view of the portion circled in FIG. 5A identified by the reference numeral 5B;
FIG. 6 is an exploded side elevational view of another embodiment of oral dispensing assembly in accordance with the present invention;
FIG. 7 is an enlarged exploded view of the tip of the plunger circled in FIG. 6 and identified by the reference numeral 7;
FIG. 8A is a transverse sectional view showing the plunger assembled in the barrel;
FIG. 8B is an enlarged fragmentary view of the portioned circled in FIG. 8A and referenced by the numeral 8B;
FIG. 9A is a transverse sectional view similar to FIG. 8A with the plunger fully withdrawn;
FIG. 9B is an enlarged view showing the relationship of the parts when the plunger and barrel are in the position shown in FIG. 9A;
FIG. 9C is an exploded, enlarged fragmentary sectional view of the plunger tip and entrance end of the barrel;
FIG. 10A is a transverse sectional view similar to FIGS. 8A and 9A where the plunger is fully bottomed out in the barrel during a discharge stroke;
FIG. 10B is an enlarged fragmentary sectional view of the portion circled in FIG. 10A and identified by the reference numeral 10B;
FIG. 11 is a transverse, sectional view of a molding apparatus for making a plunger for the dispenser assembly shown in FIGS. 6-10 inclusive;
FIG. 12 is a transverse, sectional view similar to FIG. 11 showing the first stage in the plunger part removal process;
FIG. 13 is a transverse, sectional view showing the next stage in the plunger part removal process;
FIGS. 14-16 inclusive are transverse, sectional views showing sequentially the steps for removing the plunger part;
FIG. 17 is an enlarged fragmentary, transverse, sectional view of the front and rear cavity;
FIG. 18 is a fragmentary view similar to FIG. 12; and
FIG. 19 is an enlarged fragmentary, sectional view showing the parts as they are in FIG. 13.



DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
Referring now to the drawings and particularly to FIG. 1 thereof, there is shown an oral dispensing assembly in accordance with the present invention generally designated by the numeral (10), as shown the assembly comprises an elongated plunger (12) which fits in and slides in an elongated, hollow barrel (14).
The barrel (14) as best illustrated in FIGS. 5A and 5B is made of a plastic material and comprises a generally cylindrical, elongated side wall (18) having a bore (18a) of generally uniform diameter D for its length having a tip (20) at one end with a discharge opening (22) through which medicament products are dispensed. The tip end (20) as illustrated in 5b is of a greater cross section T than the barrel side wall thickness T−1 to define a circumferentially extending ledge (24). The interior of the tip (20) is shaped to define a spherical seat (26). The barrel (14) is outwardly flared at its opposing upper terminal end as at (30) and has a pair of circumferentially extending spaced protrusions (34) and (36) in the region where the cylindrical body portion (18) of the barrel merge with the outwardly flared finger grip portion (30).
The plunger (12) is also made of plastic and has an elongated generally cylindrical elongated body portion (40) which is outwardly flared to define a flange (42) at its upper end serving as a finger grip portion for activation of the plunger in the barrel. The plunger (12) as illustrated has a bulbous nose (44) at its tip end. The nose portion (44) is offset from the side wall (40) as shown at 5B and has a cross sectional thickness T-2 slightly greater than the cross section T-3 of cylindrical body portion of the plunger. A downwardly and slightly outwardly biased sealing lip (46) projects axially from the lower end of the plunger at the juncture (48) of the cylindrical body portion (40) and nose section (44) and has a slightly beveled outer edge (47) confronting the inner wall of the barrel as shown in FIG. 3B. The tip of the sealing lip (46) is spaced upwardly from the nose portion so that when the plunger is fully seated the sealing lip (46) engages the ledge (24) when the nose portion engages the spherical seat. The sealing lip (40) projects outwardly at an angle alpha (a) of about ten degrees (10°) to the longitudinal axis A—A of the plunger.
The inside diameter D of the barrel is slightly greater than the external diameter D2 of the plunger to provide a slight clearance C between the parts so that the flexible sealing lip (46) is essentially the sole contact when activating the plunger to fill or discharge product.
The barrel (14) is preferably made of polypropylene and the plunger (12) is preferably made of a high-density polyethylene. It has been found that this combination of materials and the specific configuration facilitate easy sliding of the parts relative to one another and does not require the close molding tolerances that prior art syringes require. Further the plunger (12) is easy and economical to manufacture by reason of the simple mold design which does not require side action components. The tooling therefore is relatively simple and does not require the complex tooling which prior art syringe assemblies require. The tooling can accommodate more cavities for a given tonnage and is therefore very economical and cost saving.
Consider briefly the use of an oral dosing assembly in accordance with the present invention. With the plunger (12) fully seated in the barrel (14) as shown in FIG. 5A, the user simply inserts the barrel and plunger into a container for the medicament to be dispensed the user then pulls the plunger (12) upwardly to draw the desired quantity into the barrel. The barrel is graduated in markings to aid in the filling process. The user then simply inserts the tip end into the mouth of a child and pushes the barrel forwardly to dispense product. It is noted that when the barrel is drawn to its outer-limit position, the sealing lip (40) engages in one of the protrusions signaling the user not to withdraw the plunger any further.
There is shown in FIG. 7-10 inclusive another embodiment of dispenser assembly in accordance with the present invention generally designated by the numeral (50) which comprises an elongated, hollow barrel (52) and a plunger (54) slidably mounted in the barrel (52). The barrel (52) as illustrated has an elongated, generally cylindrical body portion (56) terminating at its upper end in radially outwardly directed circumferentially extending flange (58) providing a finger grip for the user. The tip (59) has a discharge opening (60) and is connected to the side wall (56) by a downwardly flared conical connecting wall (62).
The plunger (54) has an elongated body portion (54a) having a generally uniform diameter (D4) which has an outwardly flared section (54b) at its upper open end and terminates in a circumferentially extending radially outwardly directed flange (66) serving as a finger grip for the user to activate the plunger in the barrel. The tip end (55) of the plunger (54) has an axially extending wall (68) offset radially to provide a circumferentially extending space or pocket S between the sealing lip (40) and tip (55). The tip (55) is of a thickness T-3 greater than the cross sectional wall thickness T-4 of the body portion of the plunger. A downwardly and inwardly extending bottom wall (70) has raised a central indentation (72). The slanted outer-face of the bottom wall (70) preferably is disposed at a predetermined angle relative to a plane P—P through the axis A—A of the plunger so that it seats flush against the interior downwardly tapered face (62) of the barrel when the plunger is fully seated at the end of a discharge stroke as shown in FIG. 10A. A flexible sealing lip (40) is formed integrally with the plunger and in the relaxed state projects at an angle alpha (α) of about ten degrees (10°) relative to the axis A—A of the plunger. The sealing lip (40) has an outer beveled surface (40a) which engages the inner side wall of the barrel to provide good sliding movement when activating the plunger in the barrel. Similar to the previously described embodiment, the outer barrel is preferably made of propylene and the plunger is preferably made of a high-density polyethylene since the combination of these materials and the specific configuration of the sealing lip facilitates movement of the parts relative to one another and does not require the close molding tolerances to provide good sliding action.
The slightly outwardly tapered section (52b) of the barrel bore (52c) at the open end is preferably angularly disposed relative to the longitudinal axis A—A of the barrel at an angle beta (β) of between three and five degrees (3° and 5°) thereby defining an opening at the top of the barrel of a diameter (D6) greater than the diameter (D5) of the flexible lip (40) in the relaxed state to thereby allow easy assembly of the parts without damage to the flexible wiper lip. The flexible sealing lip (40) engages the rib (53) at the maximum stroke to signal the user that the parts are in the position shown in FIGS. 9A and 9B. As shown in the drawings, the wiper lip is compressed slightly when it rides in the main portion of the barrel to provide the desired light essentially single line contact with the bore of the barrel for ease of operation of the dispenser in a manner to provide an effective seal preventing blow by of the liquid product when activating the plunger to discharge product through the discharge opening.
It is noted that even know the dispenser assembly of the present invention has been shown and described in connection with dispensing medicaments for children, the dispensing assembly has many other useful applications for dispensing other types of liquid products. Further, even though the high-density polyethylene and polypropylene are the preferred combination of materials, in some applications, other dissimilar combinations of materials may be used which provide the good sliding action between the flexible wiper lip or flange and the interior wall of the barrel.
There is shown in FIGS. 11-19 inclusive a method and molding apparatus for manufacturing plungers for the dispenser assembly shown in FIGS. 6-10 inclusive. This method and apparatus are characterized by novel features of construction and arrangement facilitating easy and economical manufacture of plungers. The molding apparatus as shown in FIG. 11 comprises an elongated, tubular one-piece rear cavity (80) having an elongated generally cylindrical mold cavity (82) which is flared outwardly as to (83) adjacent one end to form the tapered bore section T of the plunger 54. The opposite end is also slightly tapered outwardly as at (85) to facilitate formation of the axially directed wiper lip (40). The molding apparatus also includes a front cavity (88) comprising a gate bushing (90) and a manifold probe (92). The gate bushing (90) is formed with a tapered front wall (94) which abuts a complementary tapered wall (87) on the front end of the rear cavity when the mold is closed. The gate bushing (90) has a circumferentially extending axially directed rim (94) which forms the circumferentially extending space or gap S between the wiper lip (40) and the tip portion (70) of the plunger (54) which permits the wiper lip (40) to be deflected radially inwardly when the finished plunger is withdrawn from the rear cavity as shown in FIG. 13. In otherwords, the diameter D5 of the tip portion (70) of the plunger (54) and the cross-sectional thickness Tw of the wiper lip (40) are slightly less than the outer diameter Do of the plunger to allow radially inward deflection of the wiper lip (40) when the core (95) is withdrawn in the manner shown in FIG. 13. The core (95) mounts an injector collar (93) which when actuated forwardly engages the radial flange at the outer end of the plunger (54) to strip it from the core (95) in the manner shown in FIG. 15 and FIG. 16.
Consider the operation of the molding apparatus and system described. With the mold parts in relative positions shown in FIG. 1, the gate (90a) is opened to allow the plastic material to form the part in the manner shown in FIG. 1. The gate bushing (90) is then withdrawn to the position shown in FIG. 12. When the mold is opened in this fashion to break the gate, it provides the necessary clearance to allow the flexible wiper lip (40) to collapse and be withdrawn from the mold cavity. The mold starts to open at the next position (FIG. 13) allowing the plunger part (54) to start withdrawing from the cavity while the flexible wiper lip (40) collapses radially inwardly. The mold continues to open in the manner shown in FIG. 14 allowing the plunger part to completely withdraw from the cavity while the flexible wiper lip (40) expands to its normal position and provide enough clearance to eject the plunger part (see FIG. 16). The ejector plate is activated forwardly stripping the plunger part from the core at the end of the stroke the plunger part is released from the mold (see FIG. 16).
Even though particular embodiments of the present invention have been illustrated and described herein, it is not intended to limit the invention and changes and modifications may be made therein within the scope of the following claims.

## Claims

1. A dispenser assembly, comprising:
an elongated barrel having an internal cross-sectional diameter, and
an elongated plunger having a hollow tip portion positioned within the barrel and a body portion extending from the tip portion and terminating at an upper end positioned externally from the barrel, wherein
a flexible sealing lip is formed on the hollow tip portion,
the body portion comprises a hollow, circular cylinder that extends from the hollow tip portion and is outwardly flared at the upper end to form a flange that is operable as a finger grip,
the hollow tip portion and the hollow cylinder define a closed interior volume that opens through the flared upper end of the body portion,
the sealing lip has an outer diameter in a relaxed state that is greater than the internal cross-sectional diameter of the barrel, and
when the plunger and barrel are actuated axially relative to one another, the sealing lip flexes inwardly and provides the sole contact between the plunger and the barrel.

2. The dispenser assembly of claim 1, wherein the barrel is made of a first material having a first translucence and the plunger is made of a second material that is different from the first material having a second translucence which is less than the first translucence.

3. The dispenser assembly of claim 2, where the first material is substantially translucent and the second material is substantially opaque.

4. The dispenser assembly of claim 1, wherein when the plunger and barrel are actuated axially relative to one another, the sealing lip flexes inwardly against its bias.

5. The dispenser assembly of claim 1, wherein the sealing lip is biased radially outward in the relaxed state.

6. The dispenser assembly of claim 5, wherein, when the plunger and barrel are actuated axially relative to one another, the sealing lip flexes radially inwardly.

7. The dispenser assembly of claim 1, wherein an outer peripheral edge of the flexible lip is chamfered.

8. The dispenser assembly of claim 1, wherein the sealing lip is disposed circumferentially around the hollow tip portion.

9. The dispenser assembly of claim 1, wherein the sealing lip is axially directed.

10. A dispenser assembly, comprising:
an elongated barrel having an internal cross-sectional diameter; and
a one piece elongated plunger having a body portion, a flared portion disposed at a proximal end of the body portion to define a flange that is operable as a finger grip, a hollow tip portion disposed at a distal end of the body portion, and a sealing lip disposed circumferentially around the hollow tip portion, wherein
the sealing lip has an outer diameter that is greater than the internal cross-sectional diameter of the barrel,
the body portion comprises a hollow, circular cylinder that extends from the hollow tip portion to the proximal end of the body portion,
the hollow tip portion and the hollow cylinder define a closed interior volume that opens through the flared portion of the body portion,
in a relaxed state, the outer diameter of the sealing lip is greater than the internal cross-sectional diameter of the barrel, and, when the plunger and barrel are actuated axially relative to one another, the outer diameter of the sealing lip is less than the internal cross-sectional diameter of the barrel, and
the barrel is made of a first plastic material having a first translucence and at least the flexible sealing lip and the body portion of the plunger are made of a second plastic material having a second translucence which is less than the first translucence.

11. The assembly of claim 10, wherein the diameter of the sealing lip is greater than the diameter of the hollow tip portion.

12. The dispenser assembly of claim 10, wherein the barrel is made of a first material and the plunger is made of a second material that is different from the first material the first material is substantially translucent and the second material is substantially opaque.

13. The dispenser assembly of claim 10, wherein the barrel is made entirely of a first material and the plunger is made entirely of a second material that is different from the first material.

14. The dispenser assembly of claim 10, wherein, when the plunger and barrel are actuated axially relative to one another, the sealing lip flexes inwardly against its bias.

15. The dispenser assembly of claim 10, wherein the sealing lip is biased radially outwardly in the relaxed state.

16. The dispenser assembly of claim 15, wherein, when the plunger and barrel are actuated axially relative to one another, the sealing lip flexes radially inwardly.

17. The dispenser assembly of claim 10, wherein an outer peripheral edge of the flexible lip is chamfered.

18. The dispenser assembly of claim 10, wherein the sealing lip is axially directed.

19. The dispenser assembly of claim 10, wherein, when the plunger and barrel actuated axially relative to one another, the sealing lip provides the sole contact between the plunger and the barrel.

20. A dispenser assembly, comprising:
an elongated barrel having an inner cylindrical wall that defines an internal cross-sectional diameter of the barrel; and
an elongated plunger having a shaft and a sealing lip formed on a hollow tip end of the shaft, the hollow tip end positioned within the barrel and the shaft extending from the hollow tip end toward an upper end that is positioned externally from the barrel, the sealing lip having a circular outer perimeter that defines an outer diameter in a relaxed state that is greater than the internal cross-sectional diameter of the barrel, wherein:
the shaft comprises a hollow, circular cylinder that extends from the hollow tip end to the upper end of the elongated plunger,
the hollow tip end and the hollow cylinder define a closed interior volume that opens through the upper end of the elongated plunger,
the outer perimeter of the sealing lip engages the inner wall of the barrel as the plunger and barrel are actuated axially relative to one another, and
the barrel is made of a first plastic material having a first translucence and at least the flexible sealing lip and the shaft of the plunger are made of a second plastic material having a second translucence which is less than the first translucence.

21. The dispenser assembly of claim 20, wherein the entire outer perimeter of the sealing lip engages the inner wall of the barrel as the plunger and barrel are actuated axially relative to one another.

22. The dispenser assembly of claim 20, wherein the barrel defines a discharge opening at a first end thereof and is open at a second end thereof opposite the first end, and
wherein the outer perimeter of the sealing lip begins to engage the inner wall of the barrel as the plunger is inserted into the barrel from the open end toward the discharge opening.

23. A dispenser assembly, comprising:
an elongated barrel having an internal cross-sectional diameter; and
a one piece elongated plunger having a body portion, a hollow tip portion disposed at a distal end of the body portion, an upper end portion that extends externally from the barrel, and a sealing lip disposed circumferentially around the hollow tip portion, the sealing lip having an outer diameter that is greater than the internal cross-sectional diameter of the barrel, wherein:
an air gap is defined between the sealing lip and the hollow tip portion,
the body portion comprises a hollow, circular cylinder that extends from the hollow tip portion to the upper end portion of the elongated plunger,
the hollow tip portion and the hollow cylinder define a closed interior volume that opens through the upper end portion of the elongated plunger,
and
the barrel is made of a first plastic material having a first translucence and at least the flexible sealing lip and the body portion of the plunger are made of a second plastic material having a second translucence which is less than the first translucence.

24. The assembly of claim 23, wherein the sealing lip provides the sole sliding contact between the plunger and the barrel when the plunger and barrel are actuated axially relative to one another.

25. The assembly of claim 23, wherein the air gap is diminished when the plunger and barrel are actuated axially relative to one another.

26. The assembly of claim 23, wherein the sealing lip flexes radially inwardly and diminishes the air gap when the plunger and barrel are actuated axially relative to one another.

27. The assembly of claim 23, wherein the sealing lip is biased radially outwardly in the relaxed state.

28. The dispenser assembly of claim 1, wherein the barrel is made of polypropylene and the plunger is made of polyethylene.

29. The dispenser assembly of claim 10, wherein the barrel is made of polypropylene and the plunger is made of polyethylene.

30. The dispenser assembly of claim 20, wherein the barrel is made of polypropylene and the plunger is made of polyethylene.

31. The dispenser assembly of claim 23, wherein the barrel is made of polypropylene and the plunger is made of polyethylene.