WO2011125133A1

WO2011125133A1 - Cylinder gasket and pre-filled syringe using same

Info

Publication number: WO2011125133A1
Application number: PCT/JP2010/002614
Authority: WO
Inventors: 四ッ辻晃
Original assignee: 有限会社コーキ・エンジニアリング
Priority date: 2010-04-09
Filing date: 2010-04-09
Publication date: 2011-10-13
Also published as: JP5623508B2; JPWO2011125133A1

Abstract

Provided is a cylinder gasket which naturally has good sliding properties with respect to a cylinder, that does not require the application of silicon grease to a threaded hole into which a piston is screwed, that is not susceptible to the piston being dislodged, and which is not deformed even if subjected to heat sterilization. The cylinder gasket (10) comprises: a gasket main body (12) that is made from a thermoplastic elastomer and which has sliding surfaces and the tip surface covered with a friction-reducing film (20), and has a recess (16) formed on the surface on which a piston (P) is mounted; and a base member (14) made from plastic having a higher softening point than the thermoplastic elastomer that forms the gasket main body (12), said base member having a threaded hole (18) into which the tip of the piston (P) is screwed, and said base member being mounted to the recess (16) with the threaded hole (18) open to the exterior.

Description

Gasket for syringe and prefilled syringe using the same

The present invention relates to a syringe used for administering a drug solution to a human or an animal in the medical and medical fields, particularly to a gasket for a syringe suitable for a prefilled syringe.

In the cylinder used as a syringe and a drug solution container, a drug solution for injection is filled in advance, transported and stored in a sealed and sealed state with a cap or the like at the tip portion to which the injection needle is attached. So-called pre-filled syringes are widely used in recent years to administer the drug solution in the cylinder by pressing the piston (push rod) and sliding the gasket in the direction of the tip of the cylinder after attaching the injection needle to the tip of the cylinder It has become like that.

Pre-filled syringes are characterized in that they can be administered in precise amounts without misuse of the drug solution, and transfer operations of the drug solution are unnecessary, and microbial contamination etc. of the drug solution caused by such operations can be prevented. Have.

By the way, in the conventional pre-filled syringes, the gaskets are formed of butyl rubber, thermoplastic elastomer (TPE) or the like, but these rubber gaskets improve the "slipperiness" when sliding on the inner surface of the cylinder In order to achieve this, it is necessary to apply silicone grease to the gasket surface and the inner surface of the cylinder, and the silicone grease absorbs the active ingredient in the drug solution, and the drug solution is reduced by silicone particles in the silicone grease. Contamination and its adverse effects on the human body have been regarded as problems. Moreover, there also existed a possibility that the soluble component in rubber | gum might elute in a chemical | medical solution.

Then, in order to solve the problem which concerns, the gasket 1 as shown in FIG. 5 is developed (for example, refer patent document 1). The gasket 1 improves the slidability with respect to the cylinder 4 by laminating the resin film 3 on the surface of the gasket body 2 made of rubber, making it unnecessary to apply the silicone grease to the inner surface of the cylinder 4 and removing the silicone grease. It is possible to avoid the above-mentioned problems resulting from it.

Japanese Patent Application Laid-Open No. 10-314305

However, the gasket 1 of Patent Document 1 has the following problems. That is, although the screw hole 6 for screwing the front end portion of the piston 5 is formed in the gasket body 2, the piston 5 is screwed as it is because of the poor slidability of the rubber forming the gasket body 2. Since it is difficult to screw into the hole 6, when screwing the piston 5 into the screw hole 6, it was necessary to apply silicone grease to the surface of the screw hole 6 or the tip of the piston 5.

For this reason, although it is not necessary to apply silicone grease to the inner surface of the cylinder 4 at the bending angle, the process of applying silicone grease to the surface of the screw hole 6 (or the tip of the piston 5) can not be omitted. In addition, in the worst case, when the piston 5 is screwed into the screw hole 6, the silicone grease pushed out from the screw hole 6 may adhere to the inner surface of the cylinder 4 and be mixed in the chemical solution in the cylinder 4 It was not nothing.

Further, since the rubber has relatively large flexibility, when the piston 5 is screwed into the screw hole 6 of the gasket body 2 and then the piston 5 is pulled (for example, at the time of blood collection), the ridge 6a of the screw hole 6 However, in combination with the fact that the silicone grease is applied to the screw hole 6 as described above, the piston 5 may possibly come off the screw hole 6 as described above.

As still another problem, after the cylinder 4 is filled with a chemical solution, heat sterilization (for example, steam sterilization at 120 ° C. for 20 minutes) is performed in a state where the gasket 1 is fitted into the cylinder 4 (especially thermoplastic elastomer In the case of (TPE), the heat causes the gasket 1 to be deformed, causing a gap with the inner surface of the cylinder 4 to spill out the chemical solution, or conversely, the fitting state of the gasket 1 to the cylinder 4 becomes tight. There was a risk that the gasket 1 could not easily move.

The present invention has been developed in view of such problems of the prior art. Therefore, the main object of the present invention is, of course, that the slidability with respect to the cylinder is good, there is no need to apply silicone grease to the screw hole for screwing the piston and there is no risk of the piston coming off, and heating It is an object of the present invention to provide a syringe gasket that does not deform even when subjected to sterilization treatment, and a prefilled syringe using the same.

According to the invention described in claim 1, the gasket body 12 made of thermoplastic elastomer has a sliding surface and a tip surface covered with the sliding film 20 and a recess 16 is formed on the surface to which the piston P is attached;
The thermoplastic elastomer forming the gasket body 12 is provided with a screw hole 18 into which the tip of the piston P is screwed, and is attached to the recess 16 with the screw hole 18 opened to the outside. Is a gasket 10 for a syringe characterized by comprising a plastic base member 14 having a high softening point.

According to the present invention, the gasket main body 12 formed of a thermoplastic elastomer is required for the gasket for a syringe 10 by covering the sliding surface and the tip end surface with the slidable film 20. The base member 14 is attached to the recess 16 formed in the “surface to which the piston P is attached” in the gasket main body 12 provided with “slidability and sealability with the inner surface”.

The base member 14 is formed of a plastic having a softening point higher than that of the thermoplastic elastomer forming the gasket body 12, and the gasket body is opened with the screw hole 18 to which the tip of the piston P is screwed. It is attached to twelve.

Thus, since the screw hole 18 in which the piston P is screwed is formed of plastic having much better slidability than rubber, it is easy to apply the silicone grease to the screw hole 18. The piston P can be screwed on.

Further, since plastic is less flexible than rubber, when the piston P is screwed into the screw hole 18 of the base member 14 and the piston P is pulled, the crest of the screw hole 18 is bent in the pulling direction There is no risk of the piston P coming off the screw hole 18 at all.

In addition, even if the temperature of the gasket for syringe 10 is increased to the deformable temperature of the thermoplastic elastomer due to heat at the time of heat sterilization, the base member 14 having a softening point higher than that of the thermoplastic elastomer and the slidable film 20 are formed. Since the base member 14 and the slidable film 20 play a role of a framework since they are firmly adhered to the gasket body 12 at times, the deformation of the gasket body 12 is prevented, and the inner surface of the cylinder C and the syringe Avoid the possibility that the chemical solution M may spill out due to a gap with the gasket 10 and conversely the tight fit of the syringe gasket 10 with the cylinder C may cause the syringe gasket 10 to not move easily. it can.

The invention according to claim 2 relates to the gasket 10 for a syringe according to claim 1, wherein "the gasket main body 12 is formed of a fluorine-free thermoplastic elastomer,
The base member 14 is characterized by being formed of any plastic material selected from high density polyethylene, polypropylene, cycloolefin polymer, and cyclic olefin-based copolymer.

When the gasket main body 12 is formed using a material containing fluorine in the hard segment or soft segment of the thermoplastic elastomer (hereinafter, such a material is referred to as “fluorinated thermoplastic elastomer”), the material of the fluorinated thermoplastic elastomer is The surface has low slidability (has adhesiveness) and is made of a base member 14 and a fluorine-based thermoplastic elastomer formed of a material other than “fluorinated plastic” such as a fluorine-containing thermoplastic resin The bonding strength is extremely weak with the gasket body 12 of this type, and there is a risk that the base member 14 may be pulled out of the gasket body 12 when the piston P screwed to the base member 14 is pulled. As a material of the base member 14 with respect to the gasket main body 12, a fluorine-containing thermoplastic resin or the like Tsu fluorinated plastic "only can not be used.

However, in the gasket 10 for a syringe according to the present invention, the gasket body 12 is formed of "a thermoplastic elastomer containing no fluorine", and has a high density that adheres firmly to the "thermoplastic elastomer containing no fluorine" at the time of molding. The use of polyethylene (HDPE), polypropylene (PP), cycloolefin polymer (COP), or cyclic olefin copolymer (COC) as the base member 14 does not cause the above-mentioned problems. In addition, "high density" polyethylene means the thing whose specific gravity is 0.96 or more.

The invention described in claim 3 relates to the gasket for a syringe 10 described in

claim

1 or 2, wherein "the slidable film 20 is a PTFE film,
The bonding surface of the gasket body 12 and the PTFE film 20 is subjected to an adhesion improving process.

In the present invention, PTFE (polytetrafluoroethylene, tetrafluoride) having high slidability (that is, low resistance at the time of sliding) is used as the slidable film 20 covering the sliding face and tip face of the gasket body 12. Since the ethylene) film 20 is used, the slidability of the gasket for syringe 10 with respect to the cylinder C can be further enhanced, and the slide can be performed more smoothly.

However, since the PTFE film 20 is poorly adhesive and the bonding strength with the “fluorine-free thermoplastic elastomer” constituting the gasket body 12 is extremely weak, the PTFE film 20 may be simply bonded to the gasket body 12. Although the intended molded product can not be obtained, in the gasket 10 for a syringe of the present invention, the bonding surface of the gasket body 12 and the PTFE film 20 is subjected to an adhesion improving treatment, so The gasket main body 12 can be firmly joined at the time of molding.

As the "adhesion improvement treatment", as described later, "arrangement of the silica fine particle layer 22", "chemical treatment with metal sodium", "plasma treatment in an argon atmosphere", or "the surface of the PTFE film 20" "Plasma polymerization treatment of butadiene to" is considered.

As a result, it is possible to provide the syringe gasket 10 for a syringe that has extremely high slidability with respect to the cylinder C, and that there is no concern that the PTFE film 20 is detached from the gasket body 12 due to vibration or impact.

According to the invention described in claim 4, “the cylinder C filled with the chemical solution M,
The gasket for a syringe according to any one of claims 1 to 3, which seals the cylinder C.
It is a prefilled syringe A having a piston P which pushes the gasket 10 for a syringe toward the tip of the cylinder C and whose tip is a screw P screwed into the screw hole 18.

According to the present invention, as a matter of course, the slidability with respect to the cylinder is good, there is no need to apply silicone grease to the screw hole for screwing the piston and there is no risk of the piston coming off, and heat sterilization treatment It was possible to provide a gasket for a syringe which is not deformed even when received.

It is sectional drawing of the gasket for syringes to which this invention is applied. It is sectional drawing of the prefilled syringe to which the gasket for syringes of FIG. 1 was applied. It is sectional drawing which shows another Example. It is a figure which shows the manufacture procedure of the gasket for syringes. It is a figure which shows a prior art.

Hereinafter, a gasket for a syringe 10 to which the present invention is applied will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a gasket 10 for a syringe of the present invention, and FIG. 2 is a cross-sectional view showing a prefilled syringe A to which the gasket 10 for a syringe is applied.

As shown in FIG. 2, the prefilled syringe A is generally configured of a gasket for syringe 10 (hereinafter simply referred to as “gasket 10”), a cylinder C, a piston P, and a cap K. M in the figure is a drug solution (injection solution) filled in the syringe A.

As shown in FIG. 1, the gasket 10 is made of PTFE (polytetrafluoroethylene, tetrafluoroethylene) laminated on the sliding surfaces of the gasket body 12, the base member 14, and the inner surface of the cylinder C in the gasket body 12. And a film 20.

The gasket main body 12 is a substantially cylindrical member formed of a thermoplastic elastomer, and a substantially cylindrical recess 16 to which the base member 14 is attached is formed on the bottom surface (= the surface to which the piston P is attached). There is.

The gasket body 12 of the present embodiment is a thermoplastic that uses polystyrene (PS) or polypropylene (PP) as a hard segment, and ethylene propylene (EPDM), polybutadiene (BDR), or polyisoprene as a soft segment. Although an elastomer (TPE) is employed, the material of the gasket body 12 is not limited to this, and other types of thermoplastic elastomers can be used. However, as described later, high-density polyethylene (HDPE), polypropylene, cycloolefin polymer (COP), or cyclic olefin copolymer (COC) having high adhesiveness and versatility can be used as a raw material of the base member 14 "The thermoplastic resin does not contain fluorine, in that the cost of the gasket 10 can be stably kept low due to the wide choice of materials, and it can be easily coped with the surge of demand. It is preferred to use an "elastomer".

In addition, a partially cross-linked thermoplastic elastomer (TPV) having good heating permanent strain and produced by mixing and vulcanizing simultaneously may be used, and as additives for vulcanization purpose, sulfur, many Functional silicon, bismaleimides, organic peroxides, etc. can be considered.

The base member 14 is a substantially cylindrical member formed of a plastic having a softening point higher than that of the thermoplastic elastomer forming the gasket body 12, and a screw hole in which the tip of the piston P is screwed on the bottom surface thereof. 18 is formed and attached so as to be fitted into the recess 16 of the gasket body 12 with the screw hole 18 opened to the outside.

As a material of the base member 14, any plastic having a softening point higher than that of a thermoplastic elastomer and exhibiting high adhesion to the thermoplastic elastomer can be used, but a highly versatile high density It is preferred to use polyethylene (HDPE), polypropylene, cycloolefin polymers (COP) or cyclic olefin copolymers (COC). As described above, it is necessary to use “a fluorine-free thermoplastic elastomer” for the gasket body 12 when using these materials. This is because, when using a fluorine-based thermoplastic elastomer, sufficient bonding strength can not be obtained between the gasket body 12 and the base member 14 without using “fluorinated plastic” for the base member 14 It is from.

The shape of the base member 14 is not limited to a substantially cylindrical shape having a slightly pointed end opposite to the surface on which the screw hole 18 is formed, as shown in FIG. 1, for example, as shown in FIG. The side peripheral surface at the end on the surface side where the hole 18 is formed may be shaped so as to have a ridge 21 having a circular outer shape in plan view. FIG. 3A shows an aspect in which the outer peripheral surface of the crucible 21 is covered with the PTFE film 20, and in FIG. 3B, the PTFE film 20 is disposed up to the lower surface in the drawing of the crucible 21. The aspect which the outer peripheral surface of the weir 21 exposed is shown.

By providing such a weir 21, when the temperature of the gasket 10 rises to the deformable temperature of the thermoplastic elastomer due to the heat at the time of heat sterilization etc., the gasket main body 12 bulges from the end face to which the piston P is attached. As the side circumferential surface of the base member 14 and the weir 21 cooperate to form a “frame” in different directions, deformation of the thermoplastic elastomer is made more reliable than in the case where the weir 21 is not provided. Can be prevented.

In addition, since the diameter of the collar 21 is approximately equal to the inner diameter of the cylinder C (the diameter of the collar 21 is slightly smaller), the tip of the piston P is screwed into the screw hole 18 of the base member 14. When pushed inward, the weir 21 properly guides the movement of the gasket 10, and there is no risk of the gasket 10 being pushed obliquely in the cylinder C.

Furthermore, when the male screw (= gasket attachment portion p1) of the piston P is screwed into the screw hole 18 of the base member 14, the base surface p3 (see FIG. 2) of the gasket attachment portion p1 and the wedge 21 make surface contact. Thus, the piston P can be more securely fixed to the base member 14.

The PTFE film 20 imparts high slidability to the sliding surface of the gasket main body 12 laminated on the sliding surface with the inner surface of the cylinder C in the gasket main body 12 (that is, the outer peripheral side surface of the gasket main body 12) and the tip surface. Sliding film. The thickness of the PTFE film 20 is set to 20 μm or more and 80 μm or less before lamination to the gasket body 12. This makes it difficult to obtain the PTFE film 20 economically when the thickness of the PTFE film 20 is less than 20 μm, and conversely, when the thickness of the PTFE film 20 is more than 80 μm, the elasticity of the gasket body 12 is sufficient. It is not possible to make it Of course, slidable films other than the PTFE film 20 may be laminated on the gasket body 12, but in view of the purpose of imparting high slidability to the gasket 10, it is preferable to use the PTFE film 20.

Further, the PTFE film 20 is laminated on the gasket body 12 by injection molding as described later (the thickness of the PTFE film 20 after lamination becomes 10 μm to 20 μm), and the elasticity of the gasket body 12 is inhibited. In order to avoid this, those exhibiting an elongation of at least about 250 to 650% (more precisely, elongation at break) are preferred. If the elongation rate is 300% or less, there is a risk that the PTFE film 20 may be broken at the time of molding (stretching) of the gasket 10 described later. It is more preferable to use the one having an elongation of 300% or more.

The PTFE film 20 can be produced by a method of forming the PTFE into a sheet using a casting method, a method of forming the PTFE into a block and slicing it with a blade, or a skiving process.

Here, the PTFE film 20 has a problem that the bonding strength with the “thermoplastic elastomer not containing fluorine” is extremely weak and the bonding strength with the “thermoplastic elastomer containing no fluorine” is extremely weak. "It is necessary to perform" adhesion improvement processing ", and in the present embodiment, as the" adhesion improvement processing ", the silica fine particle layer 22 is provided on the bonding surface of the PTFE film 20 and the gasket main body 12 . Of course, instead of this, chemical treatment with metallic sodium or plasma treatment in an argon atmosphere may be performed as “adhesion improvement treatment”. Furthermore, after a mixed gas of easily available 1,2-butadiene or 1,3-butadiene gas and oxygen is introduced into a vacuum chamber in which the PTFE film 20 is disposed, the plasma of the PTFE film 20 is used. Butadiene may be plasma polymerized on the surface. In this case, by using polybutadiene (BDR) as the soft segment of the gasket body 12, the same component (in this case, butadiene) is present on the gasket body 12 side and the PTFE film 20 side. The film 20 can be firmly adhered.

The silica fine particle layer 22 is composed of a binder 22a and silica (SiO2) fine particles 22b, and the PTFE film 20 and the gasket main body 12 having a poor adhesion property due to the affinity to the gasket main body 12 and the anchor effect possessed by the silica fine particles 22b It can be joined firmly. The fine silica particle 22b constituting the fine silica particle layer 22 is adhered on the surface of the PTFE film 20 in a state of being exposed to some extent from the binder 22a, and the exposed portion bites into the surface of the gasket main body 12 to exert an anchor effect. .

Specific examples of the method for forming the silica fine particle layer 22 on the surface of the PTFE film 20 include the following two methods.

The first method is a method using a PFA resin as a binder 22a for fixing the silica fine particles 22b to the surface of the PTFE film 20. Specifically, the aqueous solution of PFA resin is mixed with the silica fine particles 22b and a surfactant. · The mixed dispersion obtained by stirring is uniformly coated on one side of the PTFE film 20 using a known coating method (for example, a spray method, a roll coating method, etc.), introduced into a furnace (not shown) After drying, the PFA resin is fired at 250 to 360 ° C. using an apparatus capable of maintaining the shape of the PTFE film 20.

As a result, the PFA resin as the binder 22a is integrated with the PTFE film 20, and the silica fine particles 22b can be firmly fixed to the surface of the PTFE film 20. In addition, by baking in a temperature range and an apparatus capable of maintaining the above-mentioned shape, it is possible to prevent the elongation of the PTFE film 20 from being reduced, and as a result, the gasket 10 is suitably manufactured by compression molding or injection molding ( That is, it becomes possible to co-mold, and it is possible to prevent the PTFE film 20 from inhibiting the elasticity of the gasket body 12.

The second method is a method using a varnish in which a perfluoro fluorine resin and PFA powder are mixed as a binder 22a for fixing the silica fine particles 22b to the surface of the PTFE film 20. Specifically, a perfluoro fluorine resin and silica fine particles 22b is dispersed in a perfluoro solvent (for example, CT-solv. 100 manufactured by Asahi Glass Co., Ltd., etc.), and the varnish obtained is uniformly coated on one side of the PTFE film 20 using a known coating method, and dried. Heat treated to form. According to this method, the silica fine particle layer 22 can be efficiently formed on the surface of the PTFE film 20.

Here, the thickness of the silica fine particle layer 22 formed by each method as described above is preferably in the range of 0.5 μm to 10 μm. Within this range, both can be firmly joined without inhibiting the elongation of the PTFE film 20 and the elasticity of the gasket body 12.

The average particle diameter of the silica fine particles 22b constituting the silica fine particle layer 22 is preferably in the range of 0.02 μm to 10 μm, and more preferably in the range of 0.05 μm to 2 μm. When the average particle diameter of the silica fine particles 22b is less than 0.05 μm, the handling of the silica fine particles 22b becomes difficult, and it becomes difficult to economically manufacture the silica fine particles 22b, conversely, the silica fine particles 22b When the average particle diameter of the silica particles 22b is larger than 10 μm, the specific surface area of the silica fine particles 22b is reduced, and a sufficient anchoring effect on the gasket body 12 can not be exhibited.

The cylinder C (FIG. 2) has a needle mounting portion c1 at its front end, a finger hooking portion c2 at its rear end, and a cylindrical drug solution filling portion c3 formed between them, and in this embodiment is formed of cyclic polyolefin. . Of course, the shape of the cylinder C is not limited to that shown in the drawing, and polypropylene, glass or the like can also be used as the material of the cylinder C.

The piston P is a rod-like member having a gasket mounting portion p1 at its front end and a finger rest p2 at its rear end. The gasket mounting portion p1 of the piston P is formed with an external thread to be screwed into the screw hole 18 of the base member 14 of the gasket 10 described above. Note that, similarly to the cylinder C described above, the piston P is also made of resin such as cyclic polyolefin, polycarbonate and polypropylene, glass, and the like.

The cap K is basically formed of the same material as the cylinder C, and the needle mounting portion c1 of the cylinder C is airtightly covered, and the chemical solution filled in the cylinder C undesirably leaks from the needle mounting portion c1. It has a role to prevent release.

The procedure for producing the prefilled syringe A as described above will be described focusing on the procedure for producing the gasket 10 by insert molding.

The gasket 10, as shown in FIG. 4, opens the mold Z (FIG. 4 (a)) and inserts the base member 14 previously formed into a predetermined shape, and at the same time, the silica fine particles are formed on the surface by the method described above. The PTFE film 20 on which the layer 22 is formed is placed on the open face of the mold (FIG. 4 (b)), and after that, the thermoplastic elastomer Y which is a raw material of the gasket main body 12 is fixed in a clamped state. temperature and pressure conditions (temperature = 200 ℃ ~ 230 ℃, pressure = 500 ~ 1000kg / cm ² is suitable.) When injected at (FIG. 4 (c)), desired to PTFE film 20 is inscribed in the mold And the thermoplastic elastomer adheres firmly to the PTFE film 20 through the base member 14 and the silica fine particle layer 22. The pocket 10 is formed. Then, after the gasket 10 is cooled, the mold 10 is opened and taken out from the mold, and the unnecessary portion is trimmed if necessary, whereby the manufacturing of the gasket 10 is completed.

The tip of piston P which has been molded in advance is screwed into the screw hole 18 of the manufactured gasket 10, and thereafter, the gasket 10 is fitted to the cylinder C which has also been molded in advance and has been filled with the drug solution M. By filling in, the prefilled syringe A is completed.

According to the gasket 10 of this embodiment, since the screw hole 18 in which the piston P is screwed is formed of plastic having better slidability than rubber, silicone grease is applied to the screw hole 18 Instead, the piston P can be easily screwed.

Further, since plastic is less flexible than rubber, when the piston P is screwed into the screw hole 18 of the base member 14 and the piston P is pulled, the crest of the screw hole 18 is bent in the pulling direction There is no risk of the piston P coming off the screw hole 18.

In addition, even if the temperature of the gasket 10 rises to the deformable temperature of the thermoplastic elastomer due to heat at the time of heat sterilization or the like, the desired molded product can not be obtained (that is, the base member 14 having a higher softening point than the thermoplastic elastomer). And the PTFE film 20 laminated on the surface (sliding surface and tip surface) of the gasket body 12 plays a role of a framework to prevent deformation of the gasket body 12, and between the inner surface of the cylinder C and the gasket 10. It is possible to avoid the possibility that the chemical solution M may spill out due to a gap, or the fitting state of the gasket 10 with respect to the cylinder C may become tight and the gasket 10 may not easily move.

Furthermore, since the silica fine particle layer 22 is provided on the bonding surface between the PTFE film 20 and the gasket body 12, the affinity to the fluorine-free thermoplastic elastomer (= gasket body 12) and anchor possessed by the silica fine particle 22b As a result, the poorly adhesive PTFE film 20 and the gasket body 12 can be firmly joined. As a result, it is possible to provide the gasket 10 which has extremely high slidability with respect to the cylinder C and does not have the concern that the PTFE film 20 is detached from the gasket body 12 due to vibration or impact.

A: Prefilled syringe C: Cylinder c1: Needle mounting portion c2: Finger hook portion c3: Chemical solution filling portion P: Piston K: Cap 10: Gasket 12: Gasket main body 14: Base member 16: Recess 18: Screw hole 20: PTFE film ( Slideable film)
21 鍔 22 ... silica particle layer 22a バインダー binder 22b ... silica particle

Claims

A gasket body made of thermoplastic elastomer, the sliding surface and the tip surface being covered with a sliding film, and the recess being formed on the surface to which the piston is attached;
The piston has a screw hole into which the tip of the piston is screwed, and the softening point is higher than that of the thermoplastic elastomer forming the gasket body attached to the recess with the screw hole opened to the outside. A gasket for a syringe characterized by comprising a plastic base member.
The gasket body is formed of a fluorine-free thermoplastic elastomer,
The gasket for a syringe according to claim 1, wherein the base member is formed of any plastic material selected from high density polyethylene, polypropylene, a cycloolefin polymer, and a cyclic olefin copolymer.
The slidable film is a PTFE film,
3. The gasket for a syringe according to claim 1, wherein an adhesion improving process is applied to a bonding surface of the gasket body and the PTFE film.
A cylinder filled with a chemical solution,
The gasket for a syringe according to any one of claims 1 to 3, which seals the cylinder.
A prefilled syringe comprising: a piston for pressing the gasket for a syringe toward a tip of the cylinder; and a piston whose tip is screwed into the screw hole.