PISTON STOP FOR A MEDICAL SYRINGE AND MEDICAL SYRINGE WITH A PISTON STOP

Abstract

The invention relates to a piston stopper for a medical syringe. The piston stopper has an end wall, a side wall and an internal thread for securing a plunger rod, wherein the piston stopper is made of a butyl rubber. The end wall is conical in the distal direction both on the outside and on the inside. The end wall merges towards the side wall into a first sealing ring which extends around the circumference of the side wall. The side wall has at least three further sealing rings. Further, the invention relates to a medical syringe provided with the plunger stopper.

Claims

1. A plunger stopper for a medical syringe, the plunger stopper comprising: an end wall, a side wall, and an internal thread for securing a plunger rod, wherein the plunger stopper is made of a butyl rubber, wherein the end wall is conical in the distal direction both on the outside and on the inside, wherein the end wall merges towards the side wall into a first sealing ring, which extends around the circumference of the side wall, and wherein the side wall has at least three further sealing rings.

2. The plunger stopper according to claim 1, wherein the sealing rings have a circular segment-shaped, cross-section.

3. The plunger stopper according to claim 1, wherein the butyl rubber is a halogenated butyl rubber comprising a chlorobutyl or a bromobutyl.

4. The plunger stopper according to claim 1, wherein the internal thread is formed as a double trapezoidal thread.

5. The plunger stopper according to claim 1, further comprising a coating at least on the side wall and/or the end wall, the coating comprising a polytetrafluorethylene.

6. The plunger stopper according to claim 1, wherein a ratio of a wall thickness of the side wall to a diameter of the plunger stopper is more than 0.5 and/or less than 2.0.

7. 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.

8. The plunger stopper according to claim 1, wherein a ratio of a tooth height of the internal thread to a diameter of the plunger stopper is over 0.04 and/or under 0.15.

9. The plunger stopper according to claim 1, wherein a wall thickness of the end wall is 1 to 2 times the wall thickness of the side wall.

10. The plunger stopper according to claim 1, wherein a pitch of the internal thread is between 0.4 and 0.8 mm.

11. The plunger stopper according to claim 1, wherein a proximally first sealing ring has a proximal flank which is flattened compared to a distal flank.

12. A syringe having a plunger stopper according to claim 1.

13. The syringe according to claim 12, further comprising a plunger rod with a distal conical end, the distal conical end resting on the conical inside of the end wall.

14. The syringe according to claim 12, wherein the syringe is filled with a medical fluid and sealed with a stopper.

15. The syringe according to claim 12, wherein the syringe is autoclaved in an outer package in which the syringe is disposed.

16. The plunger stopper according to claim 6, wherein the ratio of the wall thickness of the side wall to the diameter of the plunger stopper is more than 0.9.

17. The plunger stopper according to claim 6, wherein the ratio of the wall thickness of the side wall to the diameter of the plunger stopper is less than 1.1.

18. The plunger stopper according to claim 8, wherein the ratio of the tooth height of the internal thread to the diameter of the plunger stopper is over 0.05.

19. The plunger stopper according to claim 1, wherein the wall thickness of the end wall is 1.2 to 1.6 times the wall thickness of the side wall.

20. The plunger stopper according to claim 10, wherein the pitch of the internal thread is between 0.5 and 0.7 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The subject matter of the invention will be explained in more detail below with reference to exemplary embodiments represented on the basis of the drawings FIG. 1 to FIG. 7.

[0065] FIG. 1 is a sectioned view of a medical syringe according to the invention.

[0066] FIG. 2 is a sectioned view of an exemplary embodiment of a plunger stopper.

[0067] FIG. 3 is a sectioned view along the line A-A of FIG. 2.

[0068] FIG. 4 to FIG. 7 are further sectioned views of alternative exemplary embodiments of a plunger stopper.

DETAILED DESCRIPTION OF THE DRAWINGS

[0069] FIG. 1 shows, in a sectioned view, a medical syringe 1, which is formed with a plunger stopper according to the invention.

[0070] The syringe 1 is arranged here in the 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 the outer package 2.

[0071] 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.

[0072] The inner volume of the syringe 1 can, in addition to the medical fluid 4, contain a gas, in particular air or nitrogen, in order to avoid deformations of the syringe body 3 in the case of pressure fluctuations.

[0073] 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 connected to the plunger stopper 10.

[0074] 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.

[0075] 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.

[0076] FIG. 2 is a plan view of the side wall 12 of a plunger stopper 10 according to the invention.

[0077] The outer contour of the plunger stopper 10 is rotationally-symmetric.

[0078] The plunger stopper 10 comprises a truncated cone-shaped end wall 11, wherein the cone of the end wall 11 merges seamlessly, i.e. without step, groove or similar, into a first sealing ring 13a.

[0079] The sealing rings 13b to 13d are adjoined distributed over the length of the plunger stopper 10, wherein the sealing ring 13d forms the proximal end of the plunger stopper 10.

[0080] FIG. 3 is a sectioned view along the line A-A of FIG. 2, i.e. an axial section along the rotational axis of the plunger stopper 10.

[0081] The end wall 11 is a truncated cone shape and comprises the tip angle α, which can in particular be between 140° and 160°.

[0082] The end wall 11 is formed correspondingly in a truncated cone shape on the inner side 19. Consequently, a configuration of the end wall is formed which is roof-shaped in the cross-section.

[0083] The plunger stopper 10 is provided with an internal thread 16, which is formed as a two-pass trapezoidal thread.

[0084] The plunger stopper 10 has a (maximum) diameter d.

[0085] The internal thread 16 has teeth with a tooth height z. The teeth of the internal thread 16 can be directed forwards, in particular the distal wall of the teeth can form an angle of 2° to 10° to the transversal plane.

[0086] This ensures that the outer thread 8 of the plunger rod 7 does not slip out when the plunger is pulled back.

[0087] The wall thickness of the side wall a is by definition determined without the teeth of the thread 16 and without the height h of the sealing rings 13a to 13d.

[0088] The sealing rings 13a to 13d are formed monolithically with the rest of the plunger stopper.

[0089] The sealing rings 13a to 13c are in this exemplary embodiment formed in a substantially circular segment shape in the cross-section. The sealing rings 13a to 13d can have a radius of 0.6 to 0.7 in this exemplary embodiment.

[0090] The sealing rings 13a to 13d have a height h between 0.7 to 0.8 mm.

[0091] In this exemplary embodiment, the sealing rings 13a to 13d all have the same height.

[0092] The diameter d of the plunger stopper 10 is in this exemplary embodiment 9 to 9.5 mm.

[0093] The wall thickness of the side wall 12 is 0.9 to 1.0 mm.

[0094] The proximally last sealing ring 13d has a deviating shape compared to the other sealing rings 13a to 13c.

[0095] The contour, which has a circular segment shape in the cross-section, merges into a tangent on the proximal flank 20.

[0096] This tangent can in particular form an angle of 60° to 80° towards the side wall 12.

[0097] The length 1 of the plunger stopper can be between 10 and 14 mm.

[0098] In the case of this exemplary embodiment, the internal thread 16 emerges into the tip 14 of the plunger stopper 10 via a step 18, which is located between the distal sealing ring 13a and the subsequent sealing ring 13b.

[0099] In this transition section, the inner diameter of the plunger stopper 10 corresponds roughly to the diameter between the teeth of the thread 16.

[0100] In conjunction with a correspondingly shaped plunger rod 7, pushing the plunger stopper 10 means that tensions are concentrated at the tip 14 and the material of the plunger stopper 10 located behind follows after so to speak.

[0101] This achieves an optimal tilting security.

[0102] The wall thickness b of the end wall 11 is greater than the wall thickness of the side wall 12. This is in particular 1.2 to 1.8 times as great.

[0103] The outer side 15 of the side wall is formed straight between the sealing rings 13a to 13d. The side wall 12 thus has a circular cylindrical shape in the region between the sealing rings 13a to 13d.

[0104] The exemplary embodiment represented here is provided for syringes with a fill volume of 2.25 ml.

[0105] FIG. 4 to FIG. 7 are further corresponding sectioned views of exemplary embodiments of a plunger stopper 10, wherein the diameter of the plunger stopper is greater in each case.

[0106] The plunger stopper 10 represented in FIG. 4 thus has a greater diameter than the plunger stopper represented in FIG. 3, in particular a diameter d of between 12 and 13 mm.

[0107] The sealing rings 13a to 13c can have a contour corresponding to FIG. 3 and can in particular have the same dimensions.

[0108] Unlike the exemplary embodiment according to FIG. 3, the sealing rings 13a to 13d merge into the side wall 12 via a radius r. The radius r is smaller in this exemplary embodiment than the radius of the respective circular segment which forms the sealing ring 13 to 13d, in particular 0.5 to 0.9, preferably 0.7 to 0.8 times as great.

[0109] Side wall 12 and end wall 11 are formed thicker than in the example according to FIG. 3.

[0110] In this exemplary embodiment, the side wall 12 has a size or thickness a of 1.5 to 1.7 mm and the end wall 11 of 1.8 to 2.2 mm.

[0111] The teeth of the thread 16 are enlarged compared to the exemplary embodiment according to FIG. 3, by contrast preferably in accordance with the diameter of the plunger stopper 10. They can in particular have a height z of 0.7 to 0.8 mm.

[0112] The thread 16 also merges into the tip 14 via a step 18 in the plunger stopper 10 represented in FIG. 4.

[0113] The exemplary embodiment according to FIG. 4 is provided for syringes 1 with a fill volume of 5 ml.

[0114] FIG. 5 shows an exemplary embodiment of a plunger stopper with a diameter d of 7.5 to 8.5 mm.

[0115] Unlike the embodiments represented in FIG. 3 and FIG. 4, the sealing rings 13a to 13d merge into rounded, in particular circular segment-shaped regions of the side wall 12.

[0116] The radius r of these regions of the side wall 12 can in particular be 1 to 1.5 times, preferably 1.1 to 1.3 times, the radius of the inner cross-section of the sealing rings 13a to 13d.

[0117] There is no circular cylindrical segments of the side wall located between the sealing rings 13a to 13b, but rather the intermediate spaces are rounded, in particular formed in a circular segment shape.

[0118] The radius of the inner cross-section of the sealing rings 13a to 13d can correspond to the previous exemplary embodiments.

[0119] The sealing rings 13a to 13d are in particular formed as in the case of the exemplary embodiments mentioned above.

[0120] By definition, the height h of the sealing rings 13a to 13d is understood as the height until reaching the turning point when transitioning to the radius r.

[0121] The thickness a of the side wall 12 is thus reduced by the radius r in each case.

[0122] The length 1 can also correspond to the exemplary embodiments FIG. 3 to FIG. 4.

[0123] The exemplary embodiment represented here is provided in particular for syringes with a fill volume of 10 ml.

[0124] FIG. 6 shows an embodiment of a plunger stopper 10 with a diameter d of 19.5 to 20.5 mm.

[0125] The plunger stopper has a diameter d of 18 to 22 mm.

[0126] The inner radius of the cross-section of the sealing rings 13a to 13d is roughly greater than in the previous exemplary embodiments and can in particular be between 0.8 and 1.0 mm.

[0127] The side wall 12 is formed between the sealing rings 13a to 13d on the outside in turn in a circular cylindrical shape.

[0128] The wall thickness of the side wall 12 is between 1.8 and 2.7 mm.

[0129] The wall thickness of the end wall 11 is between 2.4 to 2.8 mm.

[0130] Furthermore, the thread 16 merges directly into the tip 14 in this exemplary embodiment.

[0131] The plunger stopper 10 represented here has a length of 12 to 15 mm.

[0132] The plunger stopper 10 can be provided according to this exemplary embodiment for a syringe 1 with a fill volume of 20 mm.

[0133] FIG. 7 shows a further sectioned view of an exemplary embodiment of a plunger stopper 10.

[0134] This plunger stopper has a diameter d of 25 to 29 mm and/or a length 1 of 11 to 15 mm.

[0135] In the case of this exemplary embodiment, the inner radius of the distally first sealing ring 13a is greater than that of the subsequent sealing rings 13b to 13d.

[0136] Thus, the inner radius of the first sealing ring 13a is 1.0 to 1.3 mm, whereas the inner radius of the cross-section of the sealing rings 13b to 13d is 0.8 to 0.9 mm.

[0137] The wall thickness of the side wall 12 is 2.8 to 3.2 mm. The wall thickness of the end wall 11 is 3.6 to 4 mm.

[0138] The teeth of the thread 16 have a height h between 1.1 to 1.5 mm.

[0139] The plunger stopper 10 represented in FIG. 7 is in particular formed for syringes 1 with a fill volume of 50 ml.

[0140] Through the invention, a plunger stopper 10 optimized for pre-filled medical syringes 1 can be provided which has only a very low tendency to tilt and provides good seal-tightness.

LIST OF REFERENCE NUMERALS

[0141] α Tip angle [0142] a Thickness of the side wall [0143] b Thickness of the end wall [0144] d Diameter of the plunger stopper [0145] h Height of the sealing rings [0146] 1 Length of the plunger stopper [0147] r Radius transition sealing ring to side wall [0148] z Tooth height of the internal thread [0149] 1 Syringe [0150] 2 Outer package [0151] 3 Syringe body [0152] 4 Medical fluid [0153] 5 Nozzle [0154] 6 Stopper [0155] 7 Plunger rod [0156] 8 Thread [0157] 9 Distal end of the plunger rod [0158] 10 Plunger stopper [0159] 11 End wall [0160] 12 Side wall [0161] 13a First sealing ring [0162] 13b-13d Further sealing rings [0163] 14 Tip [0164] 15 Outer side of the outer wall [0165] 16 Thread [0166] 17 Thread base [0167] 18 Step [0168] 19 Inner side of the end wall [0169] 20 Proximal flank