Syringe gaskets and syringe barrel assemblies

Abstract

The present invention provides a syringe gasket and a syringe barrel assembly that can reduce the amount of residual drug (medicinal solution) remaining. [Solution] The syringe gasket 1 is a cylindrical body with a closed tip and an open base, and is a syringe gasket that is slidably housed in a liquid-tight and airtight state within a syringe barrel 50 described later, and is made of an elastic material, and comprises a cylindrical body portion 11 and a closed tip surface 12 located at the tip of the cylindrical body portion 11, the closed tip surface 12 having a tapered tip portion 15 that narrows in diameter toward the tip (outer diameter shrinks), and the taper angle θ1 of the tapered tip portion 15 is 120 to 170°.

Description

Technical Field

[0001] The present invention relates to a syringe gasket that is slidably housed in a syringe barrel in a liquid-tight and air-tight state, and a syringe barrel assembly.

Background Art

[0002] Conventionally, in syringes with a small capacity used for insulin administration, vaccine administration, etc., a syringe barrel with a puncture needle fixed in advance may be used. For example, in FIG. 1A of Patent Document 1 (Special Table 2023-526869), a syringe barrel is disclosed in which a perforating element (for example, a needle) (30) for injecting a therapeutic compound is attached to the tip of a barrel (20) as constituting a syringe (10). A stopper (syringe gasket) (40) is housed in the barrel (20), and by moving the stopper (40) in the axial direction of the barrel (20), the drug (drug solution) in the barrel (20) can be discharged or the drug (drug solution) can be sucked into the barrel (20).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a result of intensive studies aiming at further improving the performance of such a syringe gasket and a syringe barrel assembly, the present inventors have found that there is room for improvement, particularly in reducing the residue (remaining liquid) of the drug (drug solution) in the syringe barrel when discharging the drug (drug solution) in the syringe barrel. Therefore, the object of the present invention is to provide a syringe gasket and syringe barrel assembly that can be slidably housed in a liquid-tight and airtight state within a syringe barrel, and that can reduce the amount of residual drug (medicinal solution) remaining. [Means for solving the problem]

[0005] The following will achieve the above objectives: (1) A syringe gasket having a cylindrical body with a closed tip and an open base, which is slidably housed in a liquid-tight and airtight state within a syringe barrel, The syringe gasket is formed of an elastic material, Furthermore, it comprises a cylindrical body portion and a closed tip surface located at the tip of the cylindrical body portion, the closed tip surface having a tapered tip portion that decreases in diameter towards the tip, A syringe gasket having a taper angle of 120 to 170° at its tip.

[0006] (2) The syringe gasket according to (1) above, wherein the taper angle of the tip tapered portion of the closed tip surface is greater than the taper angle of the inner surface of the barrel tip, which is provided on the tip side of the syringe barrel and whose inner diameter decreases toward the tip, and the difference between them is 3° or less. (3) The syringe gasket is provided with a plurality of annular ribs spaced apart in the axial direction of the cylindrical body portion, The syringe gasket according to (1) or (2) above, wherein at least two of the plurality of annular ribs have the same maximum outer diameter. (4) The syringe gasket according to any one of (1) to (3) above, wherein the syringe gasket comprises a plurality of annular ribs provided at intervals in the axial direction of the cylindrical body, one of the annular ribs is provided at the base end of the closed tip surface, and has an outer diameter of 4 to 20 mm. (5) The syringe gasket according to any one of (1) to (4) above, wherein the syringe gasket comprises three or more annular ribs spaced apart in the axial direction, and the minimum outer diameter between two adjacent annular ribs is the same. (6) The syringe gasket according to any one of (1) to (5) above, wherein the tip of the tapered tip portion is an R-shaped protrusion, and the R diameter of the R-shaped protrusion is 1 to 3 mm. (7) The syringe gasket according to any one of (1) to (6) above, wherein the syringe gasket is provided with a spherical protrusion that protrudes from the base end face toward the base end and has a spherical surface smaller than a hemisphere. (8) The syringe gasket is made of cross-linked butyl rubber, as described in any of (1) to (7) above.

[0007] Furthermore, the following items will achieve the above objectives. (9) A syringe barrel assembly comprising a syringe barrel and a syringe gasket slidably housed within the syringe barrel in a liquid-tight and airtight manner, The syringe barrel is provided with an inner surface on the tip side of the lumen, and the inner diameter of the barrel tip side decreases towards the tip. The syringe gasket is formed of an elastic material, Furthermore, it comprises a cylindrical body portion and a closed end surface located at the tip of the cylindrical body portion, The syringe barrel assembly wherein the closed tip surface of the syringe gasket is provided with a tip tapered portion that decreases in diameter toward the tip, the taper angle of the tip tapered portion is 120 to 170°, and the taper angle of the tip tapered portion is greater than the taper angle of the inner surface of the barrel-side tip of the syringe barrel, and the difference between them is 3° or less.

[0008] (10) The syringe barrel assembly according to (9) above, wherein the syringe gasket comprises a plurality of annular ribs provided at intervals in the axial direction of the cylindrical body, one of the annular ribs is provided at the base end of the closed tip surface, and the outer diameter is 4 to 20 mm. [Effects of the Invention]

[0009] The syringe gasket of the present invention is a syringe gasket that is slidably housed in a liquid-tight and airtight state within a syringe barrel, is made of an elastic material, and comprises a cylindrical body portion and a closed tip surface located at the tip of the cylindrical body portion, the closed tip surface having a tapered tip portion that decreases in diameter toward the tip, and the taper angle of the tapered tip portion is 120 to 170°. This makes it possible to reduce the amount of residual drug (medication solution) in the syringe barrel.

[0010] The syringe barrel assembly of the present invention comprises a syringe barrel and a syringe gasket slidably housed within the syringe barrel in a liquid-tight and airtight manner, wherein the syringe barrel has a barrel-side tip inner surface provided on the tip side inner surface of the lumen portion, the inner diameter of which decreases toward the tip, and the syringe gasket is made of an elastic material and comprises a cylindrical body portion and a closed tip surface located at the tip of the cylindrical body portion, the closed tip surface of the syringe gasket has a tip tapered portion that decreases in diameter toward the tip, the taper angle of the tip tapered portion is 120 to 170°, and the taper angle of the tip tapered portion is greater than the taper angle of the barrel-side tip inner surface of the syringe barrel, and the difference between them is 3° or less. This makes it possible to reduce the amount of residual drug (medication solution) in the syringe barrel. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a front view showing an embodiment of the syringe gasket of the present invention. [Figure 2] Figure 2 is a cross-sectional view of AA in Figure 1. [Figure 3] Figure 3 is an enlarged view of section B in Figure 2. [Figure 4] Figure 4 is a left side view of Figure 1. [Figure 5]Figure 5 is a right side view of Figure 1. [Figure 6] Figure 6 is an enlarged front explanatory view of the syringe gasket shown in Figure 1. [Figure 7] Figure 7 is a perspective explanatory view showing an embodiment of a syringe barrel constituting a syringe barrel assembly of the present invention. [Figure 8] Figure 8 is a front explanatory view of the syringe barrel shown in Figure 7. [Figure 9] Figure 9 is a cross-sectional view taken along the line C-C of Figure 8. [Figure 10] Figure 10 is a front explanatory view showing an embodiment of a plunger attachable to the syringe gasket shown in Figure 1. [Figure 11] Figure 11 is a cross-sectional view taken along the line D-D of Figure 10. [Figure 12] Figure 12 is a cross-sectional explanatory view showing an embodiment of a syringe including the syringe gasket and the syringe barrel assembly of the present invention.

Embodiments for Carrying out the Invention

[0012] The syringe gasket and syringe barrel assembly of the present invention will be described using the embodiments shown in the drawings. The syringe gasket of the present invention is housed in a compressed state within the syringe barrel. However, the dimensions and other regulations in the following description are for the state before such compression or the state after being taken out of the syringe barrel.

[0013] As shown in FIGS. 1 to 6, the syringe gasket 1 of the present invention is a cylindrical body with a closed tip and an open base end, and is a syringe gasket that is slidably housed in a liquid-tight and airtight state within a syringe barrel 50 described later. The syringe gasket 1 is formed of an elastic material and includes a cylindrical main body portion 11 and a closed tip surface 12 located at the tip of the cylindrical main body portion 11. The closed tip surface 12 includes a tip tapered portion 15 that tapers (the outer shape (outer diameter) decreases) in the tip direction, and the taper angle θ1 of the tip tapered portion 15 is 120 to 170°.

[0014] As shown in Figures 1 to 9 and Figure 12, the syringe barrel assembly 10 of the present invention comprises a syringe barrel 50 and a syringe gasket 1 that is slidably housed inside the syringe barrel 50 in a liquid-tight and airtight state. The syringe barrel 50 has a barrel-side tip inner surface 52 provided on the tip side inner surface of the lumen 51, the inner diameter of which decreases toward the tip. The syringe gasket 1 is made of an elastic material and comprises a cylindrical body portion 11 and a closed tip surface 12 located at the tip of the cylindrical body portion 11. The closed tip surface 12 has a tip tapered portion 15 that decreases in diameter toward the tip, the taper angle θ1 of the tip tapered portion 15 is 120 to 170°, and the taper angle θ1 of the tip tapered portion 15 is greater than the taper angle θ2 of the barrel-side tip inner surface 52 of the syringe barrel 50, and the difference is 3° or less.

[0015] As shown in Figures 7 to 9, the syringe barrel 50 of this embodiment is a so-called syringe barrel with a puncture needle, comprising a cylindrical barrel body portion 53, a cylindrical puncture needle attachment portion 54 provided at the tip of the barrel body portion 53, and a puncture needle 55 having a puncture needle tip at its end, with its base end inserted into and fixed in the puncture needle attachment portion 54.

[0016] The barrel body 53 of the syringe barrel 50 is a substantially cylindrical portion capable of housing the syringe gasket 1 in a liquid-tight and slidable manner. The barrel body 53 is cylindrical in shape, extending with substantially the same inner and outer diameters, and has an internal lumen (internal space) 51 inside. The barrel body 53 also includes a shoulder portion 56 formed at the tip, which tapers in diameter toward the tip, a base end opening 57 formed at the base end, and a flange 58 that protrudes in a flat plate shape from the outer circumference of the base end.

[0017] The syringe barrel 50 in this embodiment is provided with a barrel-side tip inner surface 52 located on the inner surface of the tip side of the lumen 51 (more specifically, the inner surface of the shoulder portion 56), the inner diameter of which decreases toward the tip, and as shown in Figure 9, the taper angle θ2 of the barrel-side tip inner surface 52 is defined.

[0018] The barrel body portion 53 of the syringe barrel 50 is preferably transparent or translucent. Examples of materials for forming the barrel body portion 53 include various resins such as polypropylene, polyethylene, polystyrene, polyamide, polycarbonate, polyvinyl chloride, poly-(4-methylpentene-1), acrylic resin, polyester such as acrylonitrile-butadiene-styrene copolymer and polyethylene terephthalate, cyclic olefin polymers, and cyclic olefin copolymers. Among these, polypropylene and cyclic polyolefins (e.g., cyclic olefin polymers, cyclic olefin copolymers) are preferred because they are easy to mold and have heat resistance.

[0019] The inner diameter db of the barrel body 53 is appropriately selected depending on the intended use of the syringe barrel 50 (type and amount of drug / medicine, etc.), but is preferably 4 to 20 mm. In this embodiment, the inner diameter db of the barrel body 53 is shown as being the same along its entire axial length, but there may be slight differences in the inner diameter depending on the part due to draft angles, etc. In that case, it is sufficient if at least a part of it is within the following range. Also, the axial length Lb of the barrel body 53 (here, as shown in Figure 8, the length from the base end of the barrel body 53 to the base end of the shoulder 56) is appropriately selected depending on the intended use of the syringe barrel 50 (type and amount of drug / medicine, etc.), but is preferably 40 to 120 mm.

[0020] As shown in Figures 1 to 6, the syringe gasket 1 of this embodiment is a cylindrical body having a closed tip and a base opening. The syringe gasket 1 comprises a cylindrical main body portion 11 extending with substantially the same outer diameter, and a closed tip surface 12 located at the tip of the cylindrical main body portion 11.

[0021] The axial length La of the syringe gasket 1 is selected appropriately depending on the intended use of the syringe barrel (type and amount of drug / medicine, etc.), but is preferably 6 to 15 mm.

[0022] The closed tip surface 12 is provided with a tapered tip portion 15 that narrows in diameter (outer diameter) towards the tip. In this embodiment, the tapered tip portion 15 is formed from the tip of the syringe gasket 1 to the entire closed tip surface 12 and up to the first annular rib 21, which will be described later.

[0023] As shown in Figure 2, the taper angle θ1 of the tip tapered portion 15 is 120 to 170°. The lower limit of the taper angle θ1 of such a tip tapered portion 15 may be 125°, 130°, or even 135°. The upper limit of the taper angle θ1 of such a tip tapered portion 15 may be 165° or 160°. In this embodiment, the taper angle θ1 is defined by the portion of the tip tapered portion 15 excluding the R-shaped convex portion 16, which will be described later. The outer surface of the tip tapered portion 15 may be curved so as to bulge slightly outward or concave inward.

[0024] Preferably, the taper angle θ1 of the tapered tip portion 15 of the closed tip surface 12 is greater than the taper angle θ2 (see Figure 9) of the inner surface 52 of the barrel-side tip, which is located on the tip side of the syringe barrel 50 and whose inner diameter decreases towards the tip, and the difference between them is 3° or less. As a result, when the syringe gasket 1 is advanced inside the syringe barrel 50, the tapered tip portion 15 of the syringe gasket 1 and the inner surface 52 of the barrel-side tip of the syringe barrel 50 come into contact from the outer circumference inward, thereby reducing the amount of residual drug (medicinal solution) inside the syringe barrel. Furthermore, considering the change in shape of the syringe gasket 1 when it is stored (compressed) inside the syringe barrel 50, it is preferable to set the taper angle θ1 of the tip tapered portion 15 of the syringe gasket 1 such that the taper angle of the tip tapered portion 15 when stored (compressed) is greater than the taper angle θ2 of the inner surface 52 of the barrel-side tip of the syringe barrel 50. In addition, it is preferable that the drug discharge port (communication port with the puncture needle 55) of the syringe barrel 50 is located approximately at the radial center.

[0025] The tip of the tapered tip portion 15 is an R-shaped protrusion 16, and the R diameter (radius of curvature) R1 of the R-shaped protrusion 16 is preferably 1 to 3 mm. This prevents damage to the tip of the tapered tip portion 15 while further reducing the amount of residual drug (medicinal solution) in the syringe barrel.

[0026] The syringe gasket 1 has a plurality of (in this case, three) annular ribs (first annular rib 21, second annular rib 22, and third annular rib 23) spaced apart in the axial direction of the cylindrical body portion 11, and the maximum outer diameter Dmax of at least two of the plurality of annular ribs (in this embodiment, all of the first annular rib 21, second annular rib 22, and third annular rib 23) is the same. As a result, axial misalignment of the syringe gasket 1 when housed in the syringe barrel is reduced, improving liquid tightness and airtightness.

[0027] Specifically, as shown in Figures 1, 2, and 6, the first annular rib 21 is provided so as to protrude outward from the tip side of the syringe gasket 1. Preferably, the outer diameter of the first annular rib 21 defines the maximum outer diameter Dmax of the annular ribs 21, 22, and 23. Furthermore, in this embodiment, the tip surface (tip-side annular surface) of the first annular rib 21 is continuous with the closed tip surface 12 (tip tapered portion 15). In other words, the syringe gasket 1 comprises a plurality of annular ribs 21, 22, and 23 provided at intervals in the axial direction of the cylindrical body portion 11, and one of the annular ribs (here, the first annular rib 21) is provided at the base end of the closed tip surface 12. This makes it less likely for the drug (liquid) in the syringe barrel to leak out towards the base end than the first annular rib 21, and reduces residual liquid. The outer diameter of such annular rib (first annular rib 21) is preferably 4 to 20 mm.

[0028] In the syringe gasket 1, the second annular rib 22 is provided to protrude outward by a predetermined length towards the base end of the first annular rib 21, and the third annular rib 23 is provided to protrude outward by a predetermined length towards the base end of the second annular rib 22. In this embodiment, the maximum outer diameter Dmax of the first annular rib 21, the second annular rib 22, and the third annular rib 23 are the same, but it is not necessary for all annular ribs (first annular rib 21, second annular rib 22, and third annular rib 23) to have the same maximum outer diameter; it is sufficient if at least two of the annular ribs (for example, the first annular rib 21 and the second annular rib 22, or the first annular rib 21 and the third annular rib 23) have the same maximum outer diameter.

[0029] The maximum outer diameter of the syringe gasket 1 (i.e., the maximum outer diameter Dmax of the annular ribs 21, 22, and 23) is selected appropriately depending on the intended use of the syringe barrel (type and amount of drug (medication), etc.), but is preferably between 4 and 20 mm.

[0030] The syringe gasket 1 comprises three or more (in this case, three) annular ribs (first annular rib 21, second annular rib 22, third annular rib 23) spaced apart in the axial direction, and the minimum outer diameter (diameter of the valley between the ribs) between two adjacent annular ribs is the same. Specifically, in this embodiment, the minimum outer diameter D1min of the portion between the first annular rib 21 and the second annular rib 22 (first valley 24) and the minimum outer diameter D2min of the portion between the second annular rib 22 and the third annular rib 23 (second valley 25) are the same. This improves the moldability of the syringe gasket 1.

[0031] In addition, the minimum outer diameters D1min and D2min between two adjacent annular ribs (first valley 24 and second valley 25) in the syringe gasket 1 are appropriately selected depending on the intended use of the syringe barrel (type and amount of drug (medication) etc.), but are preferably between 3 and 19 mm.

[0032] Furthermore, in the syringe gasket 1, the protruding height h1 of the annular ribs 21, 22, and 23 (in this embodiment, half of the difference between the maximum outer diameter Dmax of the annular ribs 21, 22, and 23 and the minimum outer diameters D1min and D2min between two adjacent annular ribs (first valley 24 and second valley 25) is preferably 0.2 to 1 mm.

[0033] Furthermore, as shown in Figure 6, it is preferable that a straight section parallel to the axial direction of the syringe gasket 1 is provided for a predetermined length between two adjacent annular ribs (first valley 24 and second valley 25).

[0034] In this embodiment, the third annular rib 23, which is located at the base end of the annular ribs, is positioned a predetermined length further forward than the base end opening 13 (the base end of the cylindrical body portion 11). Furthermore, in this embodiment, the minimum outer diameter D3min of the portion of the syringe gasket 1 closer to the base end than the third annular rib 23 is larger than the minimum outer diameters D1min and D2min between the two adjacent annular ribs (first valley portion 24 and second valley portion 25) as described above.

[0035] In the syringe gasket 1 of this embodiment, as shown in Figure 6, it is preferable that the axial spacing between two adjacent annular ribs (the spacing P1 between the top of the first annular rib 21 and the top of the second annular rib 22, and the spacing P2 between the top of the second annular rib 22 and the top of the third annular rib 23) is approximately the same, or that spacing P2 is larger than spacing P1. In other words, it is preferable that the spacing P2 between two adjacent annular ribs closer to the proximal end (here, the second annular rib 22 and the third annular rib 23) is larger than the spacing P1 between two adjacent annular ribs closer to the tip (here, the first annular rib 21 and the second annular rib 22). The axial spacings P1 and P2 between two adjacent annular ribs are appropriately selected depending on the application of the syringe barrel (type and amount of drug (medication), etc.), but it is preferable that they be set in the range of 1 to 8 mm.

[0036] The number of annular ribs in a syringe gasket is not limited to the three mentioned above, and is selected appropriately depending on the intended use of the syringe barrel (type and amount of drug / medicine, etc.). However, syringe gaskets are preferably equipped with two to four annular ribs.

[0037] The syringe gasket 1 of this embodiment comprises a base end opening 13 located at the base end of a cylindrical body portion 11 and a plunger mounting portion 14 formed inside. Specifically, as shown in Figure 2, the syringe gasket 1 is provided with a recess 17 extending inward from the base end opening 13, and this recess 17 serves as the plunger mounting portion 14. A female thread is formed on the inner surface of the plunger mounting portion 14, which can be screwed into a male thread formed on the outer surface of a gasket mounting portion 61 formed at the tip of the plunger 60, which will be described later.

[0038] An example of a plunger to be attached to the syringe gasket 1 of this embodiment will be described with reference to Figures 10 and 11. The plunger 60 of this embodiment comprises a main body portion 62 extending in the axial direction, a gasket mounting portion 61 provided at its tip, a disc-shaped pressing portion 63 provided at the base end of the main body portion 62, and a disc-shaped gasket pressing portion 64 provided between the main body portion 62 and the gasket mounting portion 61. The outer surface of the gasket mounting portion 61 has a male threaded portion that screws into the plunger mounting portion (female threaded portion) 14 of the syringe gasket 1. The plunger 60 is attached to the syringe gasket 1 by screwing the plunger mounting portion (female threaded portion) 14 of the syringe gasket 1 and the gasket mounting portion (male threaded portion) 61 of the plunger 60 together. Note that the plunger may not be attached to the syringe gasket and may be attached to the gasket when in use. This prevents the plunger from being accidentally pressed before use.

[0039] Furthermore, the plunger mounting portion of the syringe gasket does not need to have a female thread, and the gasket mounting portion of the plunger does not need to have a male thread. In other words, the tip of the plunger (gasket mounting portion) may simply fit into the plunger mounting portion (recess) of the syringe gasket. Furthermore, the plunger may contact the gasket and move the gasket. Furthermore, the syringe gasket may be solid (without the base opening or plunger mounting portion described above).

[0040] It is preferable to use rigid or semi-rigid resins such as high-density polyethylene, polypropylene, polystyrene, or polyethylene terephthalate as the constituent material of the plunger 60.

[0041] The syringe gasket 1 includes a spherical projection 26 that protrudes in the direction toward the proximal end from the base end surface (here, the base end annular surface formed around the base end opening 13 of the syringe gasket 1) and has a spherical surface smaller than a hemisphere. In other words, the projection height h2 of the spherical projection 26 is smaller than the radius of curvature R2. By making the spherical projection 26 have a spherical surface smaller than a hemisphere in this way, damage to the spherical projection 26 can be prevented, and the release properties during molding of the syringe gasket 1 are also improved. The radius of curvature R2 of the spherical surface of the spherical projection 26 can be, for example, 0.2 to 0.6 mm, in which case the projection height h2 of the spherical projection 26 can be 0.1 to 0.5 mm. Furthermore, the spherical protrusion 26 is capable of contacting the gasket pressing portion 64 of the plunger 60 when the plunger 60 attached to the syringe gasket 1 is pushed (moved towards the tip).

[0042] In this embodiment, four spherical protrusions 26 are provided, and these four spherical protrusions 26 are arranged at equal intervals (90° intervals) in the circumferential direction. Preferably, 3 to 8 spherical protrusions 26 are provided, and it is preferable that the multiple spherical protrusions 26 are arranged at equal intervals in the circumferential direction.

[0043] The constituent material of the syringe gasket 1 can be any known material that has been conventionally used for syringe gaskets. Examples include rubber and elastomers. Preferred rubbers include natural rubber, isoprene rubber, butyl rubber, chloroprene rubber, nitrile-butadiene rubber, styrene-butadiene rubber, and silicone rubber, with vulcanized rubber being particularly preferred. Preferred elastomers include polyvinyl chloride elastomers, polyolefin elastomers, styrene elastomers, polyester elastomers, polyamide elastomers, polyurethane elastomers, and mixtures thereof. It is preferable that the syringe gasket 1 be made of crosslinked butyl rubber.

[0044] The syringe gasket 1 may have a low-drug-adsorbing substance coated on the tip portion. Such a low-drug-adsorbing substance can be a known substance that has been used conventionally, such as polyparaxylylene, polyolefin resins, fluororesins, or polyester resins. Polyparaxylylene can be either poly(paraxylylene) in which the aromatic ring is not substituted with a functional group, or poly(paraxylylene) in which a functional group is introduced into the aromatic ring or methylene group. For example, it could be poly(chloroparaxylylene) in which chlorine is substituted into the aromatic ring, polymethylparaxylylene in which a methyl group is substituted into the aromatic ring, or polyfluoroparaxylylene in which fluorine is substituted into the methylene group. Preferred polyolefin resins include polypropylene, ultra-high molecular weight polyethylene, poly(4-methylpentene-1), and cyclic polyolefins. Preferred fluororesins include tetrafluoroethylene-perfluoroethoxyethylene copolymer, polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, and tetrafluoroethylene / hexafluoropropylene copolymer.

[0045] Furthermore, the surface of the syringe gasket that comes into contact (slides) with the inner surface of the syringe barrel (for example, the annular ribs 21, 22, 23) can be coated with a lubricant or the like. Examples of such lubricants include silicone oil.

[0046] As shown in Figure 12, the syringe gasket 1 of this embodiment can be used as a syringe 100 by combining it with the syringe barrel 50 and plunger 60 described above. In the syringe 100 shown in Figure 12, a seal cap 70 for sealing (protecting) the tip of the puncture needle 55 is attached to the syringe barrel 50.

[0047] Within the syringe 100 (syringe barrel 50), a drug (medicinal solution) can be stored in the space formed between the barrel body 53 and the syringe gasket 1. As shown in Figure 12, the syringe 100 can also be used with the drug (medicinal solution) 71 pre-filled (a so-called pre-filled syringe).

[0048] Even in such a syringe 100, the taper angle θ1 of the tapered tip portion 15 of the syringe gasket 1 is appropriate, which allows for a reduction in residual drug (medicinal solution) in the syringe barrel. [Explanation of symbols]

[0049] 1. Syringe gasket 10 Syringe barrel assembly 11. Cylindrical main body 12 Closed tip surface 13 Proximal opening 14 Plunger mounting section 15. Tapered tip 16 R-shaped convex part 21. First annular rib 22. Second annular rib 23 Third annular rib 26 Spherical protrusion 50 syringe barrels 52 Inner surface of the barrel end 60 plungers

Claims

1. A syringe gasket having a cylindrical shape with a closed tip and an open base, which is slidably housed in a liquid-tight and airtight state within a syringe barrel, The syringe gasket is formed of an elastic material, Furthermore, it comprises a cylindrical body portion and a closed tip surface located at the tip of the cylindrical body portion, the closed tip surface having a tapered tip portion that decreases in diameter towards the tip, A syringe gasket characterized in that the taper angle of the tip tapered portion is 120 to 170°.

2. The syringe gasket according to claim 1, wherein the taper angle of the tip tapered portion of the closed tip surface is greater than the taper angle of the inner surface of the barrel tip, which is provided on the tip side of the syringe barrel and whose inner diameter decreases toward the tip, and the difference between them is 3° or less.

3. The syringe gasket comprises a plurality of annular ribs provided at intervals along the axial direction of the cylindrical body portion, The syringe gasket according to claim 1, wherein at least two of the plurality of annular ribs have the same maximum outer diameter.

4. The syringe gasket according to claim 1, wherein the syringe gasket comprises a plurality of annular ribs provided at intervals in the axial direction of the cylindrical body, one of the annular ribs is provided at the base end of the closed tip surface, and has an outer diameter of 4 to 20 mm.

5. The syringe gasket according to claim 1, wherein the syringe gasket comprises three or more annular ribs spaced apart in the axial direction, and the minimum outer diameter between two adjacent annular ribs is the same.

6. The syringe gasket according to claim 1, wherein the tip of the tapered tip portion is an R-shaped convex portion, and the R diameter of the R-shaped convex portion is 1 to 3 mm.

7. The syringe gasket according to any one of claims 1 to 6, wherein the syringe gasket comprises a spherical protrusion that protrudes from the base end surface toward the base end and has a spherical surface smaller than a hemisphere.

8. The syringe gasket according to any one of claims 1 to 6, wherein the syringe gasket is made of cross-linked butyl rubber.

9. A syringe barrel assembly comprising a syringe barrel and a syringe gasket slidably housed within the syringe barrel in a liquid-tight and airtight manner, The syringe barrel is provided with an inner surface on the tip side of the lumen, and the inner diameter of the barrel tip side decreases towards the tip. The syringe gasket is formed of an elastic material, Furthermore, it comprises a cylindrical body portion and a closed end surface located at the tip of the cylindrical body portion, The syringe barrel assembly is characterized in that the closed tip surface of the syringe gasket has a tip tapered portion that decreases in diameter toward the tip, the taper angle of the tip tapered portion is 120 to 170°, and the taper angle of the tip tapered portion is greater than the taper angle of the inner surface of the barrel-side tip of the syringe barrel, and the difference between them is 3° or less.

10. The syringe barrel assembly according to claim 9, wherein the syringe gasket comprises a plurality of annular ribs spaced apart in the axial direction of the cylindrical body, one of the annular ribs is provided at the base end of the closed tip surface, and has an outer diameter of 4 to 20 mm.

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