MEDICAL SYRINGE AND PISTON STOPPERS FOR A MEDICAL SYRINGE

Abstract

The invention relates to a piston stopper (10) for a medical syringe (1) wherein the piston stopper (10) has an end wall (11), a lateral wall (12) and an internal thread (16) for securing a piston rod (7). The piston stopper (10) comprises a main body (10a) which made of a cycloolefin, in particular a cycloloefin copolymer or a cycloolefin polymer. A plurality of sealing rings (13a-13d) that are made from a plastic material extend around the main body of the piston (10) and are materially bonded to the main body of the piston (10a). The invention furthermore relates to a medical syringe (1) and to a method for the production thereof.

Claims

1. A plunger stopper for a medical syringe the plunger stopper comprising: an end wall, a lateral wall and an internal thread for securing a plunger rod, and a main body, which comprises a cycloolefin, with a plurality of sealing rings made of an elastic material extending around the main body and connected in a materially-bonded manner to the main body.

2. The plunger stopper according to claim 1, wherein the main body is overmolded with the sealing rings.

3. The plunger stopper according to claim 2, wherein the sealing rings are formed in the cross-section of a circular segment and a polygonal base.

4. The plunger stopper according to claim 1, wherein the sealing rings sit in circumferential grooves of the main body.

5. The plunger stopper according to claim 1, wherein the plurality of sealing rings comprises at least three sealing rings.

6. The plunger stopper according to claim 1, wherein a distally first sealing ring is covered at least partially distally by a circumferential web of the main body.

7. The plunger stopper according to claim 6, wherein: the end wall of the main body of the plunger merges into the circumferential web at an edge and/or circumferential web has a height of less than 1 mm and/or the circumferential web is rounded at the edge and/or the distally first sealing ring protrudes in a plan view of the distal side of the plunger stopper between 0.05 and 0.5 mm beyond an outer edge of the web and/or the circumferential web rests on an inner wall of the syringe body.

8. The plunger stopper according to claim 1, wherein the cycloolefin comprises at least one cycloolefin selected from a group consisting of cycloolefin copolymer, cycloolefin polymer and crystal clear polymer.

9. The plunger stopper according to claim 1, wherein the plurality of sealing rings comprise at least one plastic selected from a group consisting of butyl rubber, silicone and polypropylene.

10. The plunger stopper according to claim 1, wherein a proximal tip angle of the end wall corresponds substantially to a distal tip angle of the end wall.

11. A syringe with a plunger stopper according to claim 1.

12. A syringe with a plunger stopper according to claim 6, wherein the circumferential web rests on the an inner wall of the syringe body.

13. The syringe according to claim 11, wherein the syringe has a plunger rod with a conical distal end, which, with the plunger rod is connected to the plunger stopper, rests on a conical inner side of the end wall of the plunger stopper.

14. The syringe according to claim 11, comprising a syringe body and the plunger stopper inserted into the syringe body, wherein the plurality of sealing rings comprises a first sealing ring is covered at least partially distally by a circumferential web of the main body of the plunger, wherein the web protrudes radially from the main body and the main body has a smaller outer diameter than the circumferential web proximally behind the first sealing ring.

15. A method for manufacturing a syringe according to claim 11, comprising the steps: injection-molding a syringe body which is formed at least in sections of a first material, injection-molding the main body of the plunger stopper from the first material, injecting the plurality of sealing rings on the main body to form the plunger stopper, inserting the plunger stopper into the syringe body.

16. The plunger stopper according to claim 3, wherein the polygonal base comprises a rectangular base.

17. The plunger stopper according to claim 5, wherein the plurality of sealing rings comprises at least four sealing rings.

18. The plunger stopper according to claim 7, wherein the circumferential web has a height of less than 0.5 mm.

19. The plunger stopper according to claim 7, wherein the distally first sealing ring protrudes in a plan view of the distal side of the plunger stopper between 0.08 and 0.2 mm beyond an outer edge of the web.

20. The plunger stopper according to claim 9, wherein the butyl rubber comprises a halogenated butyl rubber comprising chlorobutyl or bromobutyl.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The subject matter of the invention will be explained in more detail below on the basis of the drawings FIG. 1 to FIG. 5 with reference to exemplary embodiments.

[0073] FIG. 1 is a sectioned view of an exemplary embodiment of a syringe according to the invention.

[0074] FIG. 2 is a side view of the plunger stopper used for the syringe.

[0075] FIG. 3 is a sectioned view along the line A-A of FIG. 2.

[0076] FIG. 4 is a sectioned view of a further exemplary embodiment of a plunger stopper.

[0077] FIG. 5 shows the method steps according to one exemplary embodiment of the invention for manufacturing a syringe.

DETAILED DESCRIPTION OF THE DRAWINGS

[0078] FIG. 1 shows, in a side view, a medical syringe 1 which is equipped with a plunger stopper 10 according to the invention.

[0079] The syringe 1 is arranged here in a schematically represented outer package 2. The outer package 2 is formed as a tear-open foil package and the syringe 1 has been autoclaved in particular in the outer package 2.

[0080] The syringe 1 comprises a syringe body 3, which provides a volume which is pre-filled with a medical fluid 4. The nozzle 5 of the syringe 1 is sealed with a stopper 6.

[0081] In addition to the medical fluid 4, the inner volume of the syringe 1 can contain a gas, in particular nitrogen, which is free of or reduces oxygen, in order to avoid deformations of the syringe body 3 in the case of pressure fluctuations.

[0082] In order to expel the medical fluid 4 after removing the stopper 6, the syringe 1 comprises a plunger rod 7 with a proximal gripping end, which is pre-assembled here by way of example, said gripping end being connected to the plunger stopper 10 via its distal end. To this end, the plunger rod 7 comprises an external thread 8, which is screwed into the internal thread 16 of the plunger stopper 10. The distal end 9 of the plunger rod 7 is conical, in this exemplary embodiment cone-shaped, and rests on the end wall 11 of the plunger stopper 10 correspondingly formed on the inside.

[0083] The plunger rod 7 may also not be pre-assembled, for example provided lying next to the syringe body 3 in the outer package 2 (not represented here).

[0084] FIG. 2 shows, in a side view, an exemplary embodiment of a plunger stopper 10 according to the invention.

[0085] The plunger stopper 10 comprises a conical, in particular truncated cone-shaped end wall 11 and a substantially circular-cylindrical lateral wall 12.

[0086] In the exemplary embodiment represented here, the plunger stopper 10 comprises in total four sealing rings 13a to 13d which project or protrude radially from the lateral wall 12.

[0087] A distally first sealing ring 13a directly adjoins the end wall 11 in an axial direction. A proximally first sealing ring 13d forms the proximal end of the plunger stopper 10.

[0088] As represented in the sectioned view according to FIG. 3, the plunger stopper 10 is formed by a main body of the plunger 10a and the injected sealing rings 13a to 13d.

[0089] The main body of the plunger 10a is formed of a cycloolefin, whereas the sealing rings 13a to 13d are formed of a different elastic material, such as for example a halogenated butyl rubber.

[0090] The sealing rings 13a to 13d sit in grooves 15 of the lateral wall 12 of the main body of the plunger 10a in the exemplary embodiment represented here.

[0091] An intermediate region, which runs straight, in particular is formed circular-cylindrically in the sectioned view, and which forms a circumferential web 18 in each case, is present between the sealing rings 13a to 13d.

[0092] In this exemplary embodiment, the sealing rings 13a to 13d have in their base region substantially the same cross-section. Said cross-section is formed of a circular segment-shaped, in particular semi-circular section, which merges into a polygonal, in particular substantially rectangular base section, which sits in a groove 15 in each case.

[0093] Thus, an optimal connection is provided between the sealing rings 13a to 13d and the main body of the plunger 10a.

[0094] In this exemplary embodiment, the inner radius r of the circular segment-shaped section is 0.8 to 1.2 mm. The sealing rings 13a to 13d have a total height h of between 1.0 to 1.5 mm.

[0095] By definition, the wall thickness a of the lateral wall 12 is determined from the distance of the inner wall to the circumferential web 18 between the sealing rings 13a to 13d. Thus, the wall thickness a is not reduced by the grooves 15 by definition. In this exemplary embodiment, the wall thickness a is between 1.3 and 1.8 mm.

[0096] The teeth of the internal thread 16 formed as a double trapezoidal thread protrude from the inner side of the lateral wall 12. The tooth height z between the tooth base 17 and the tooth tip can in particular be 1.2 to 1.7 mm. The internal thread 16 extends here substantially beyond the total length of the lateral wall 12.

[0097] The end wall 11 is a truncated cone shape and has a tip 14 with the tip angle α of 140 to 160°. The inner side 19 of the end wall 11, i.e. the distal side is formed correspondingly conical here, such that a uniform wall thickness b is formed. In this exemplary embodiment, the wall thickness b of the end wall 11 is 1.2 to 1.6 times the wall thickness a of the lateral wall.

[0098] The plunger stopper 10 has a total length 1 of 14 to 16 mm. In this exemplary embodiment, the diameter d is between 18 and 20 mm. The plunger stopper represented here is formed for syringes 1 with a fill volume of roughly 20 ml.

[0099] In order to reduce the contact of the filled medical fluid with the sealing rings 13a to 13d, the main body of the plunger 10a comprises a distally circumferential web 20, which directly adjoins the upper side of the end wall 11.

[0100] The web 20 protrudes radially outwards in a plate-shaped manner and is aligned perpendicular to the central axis of the plunger stopper 10. The length in the axial direction of the web 20 is less than 0.5 mm.

[0101] The web 20 directly adjoins the distally foremost sealing ring 13a. Thus, the web 20 forms a cover, which covers the sealing ring 13a in the inserted state.

[0102] The sealing ring 13a protrudes between 0.08 and 0.15 mm beyond the outer edge of the web 20 in the non-inserted state represented here.

[0103] When the plunger stopper 10 is inserted into the syringe body 3, the sealing rings 13a to 13d are compressed and the web 20 preferably rests directly on the inner wall of the syringe body 3 in such manner that the plunger stopper 10 can be pushed in the syringe body 3.

[0104] In order to achieve improved sliding properties, the web 20 is rounded at the edges, in particular with an edge radius of between 0.2 and 0.4 mm.

[0105] FIG. 4 shows an exemplary embodiment of a plunger stopper 10, which is formed for larger syringes 1, preferably with an inner volume of 50 ml. The sealing rings 13a to 13d and the edge-side, circumferential web 20 are formed corresponding to FIG. 3.

[0106] The diameter d of the plunger stopper is between 25 and 28 mm. The lateral wall 12 and/or the end wall 11 are formed thicker roughly corresponding to the diameter. The length 1 is, in contrast, substantially identical to the plunger stopper 10 represented in FIG. 3.

[0107] FIG. 5 shows, in a flow diagram, the steps of a method according to the invention for manufacturing a medical syringe 1 according to one exemplary embodiment of the invention.

[0108] First, a syringe body 3, which is formed at least in sections of a first material, is injection-molded by means of an injection-molding process.

[0109] The first material preferably forms at least the inner wall of the syringe body 3. This may in particular be a cycloolefin. Then, a main body of the plunger 10a is injection-molded from the same material, in particular also from a cycloolefin. At least one sealing ring 13a-13d, preferably a plurality of sealing rings 13a-13d, is injected on the main body of the plunger 10a to form a plunger stopper 10. The plunger stopper 10 can now be inserted into the syringe body 3. The syringe 1 is preferably filled and sealed beforehand with a stopper 6. The syringe 1 can then be inserted into an outer package 2. The syringe 1 is autoclaved in the outer package 2 and is now also provided as a sterile finished syringe for extended storage.

[0110] A syringe 1 suitable for finished syringes can be provided with improved properties by way of the invention.

LIST OF REFERENCE NUMERALS

[0111] α Tip angle [0112] a Thickness of the lateral wall [0113] b Thickness of the end wall [0114] d Diameter of the plunger stopper [0115] h Height of the sealing rings [0116] 1 Length of the plunger stopper [0117] r Inner radius of a sealing ring [0118] z Tooth height of the internal thread [0119] 1 Syringe [0120] 2 Outer package [0121] 3 Syringe body [0122] 4 Medical fluid [0123] 5 Nozzle [0124] 6 Stopper [0125] 7 Plunger rod [0126] 8 External thread of the plunger rod [0127] 9 Distal end of the plunger rod [0128] 10 Plunger stopper [0129] 10a Main body of the plunger [0130] 11 End wall [0131] 12 Lateral wall [0132] 13a-13d Sealing ring [0133] 14 Tip [0134] 15 Groove [0135] 16 Internal thread [0136] 17 Tooth base [0137] 18 Circumferential web of the lateral wall [0138] 19 Inner side of the end wall [0139] 20 Web