JPH05131029A - Syringe - Google Patents

Abstract

PURPOSE:To provide a syringe capable of impregnating an injection slowly and accurately, and preventing a lubricant from being mixed with the injection. CONSTITUTION:This syringe has an outer cylinder 1 and a plunger 2, and a gasket 3 is coupled to the end of the plunger 2. The gasket 3 is in close contact with the internal surface of the outer cylinder 1, and the plunger 2 is freely slidable on the internal surface thereof via the gasket 3. This gasket 3 comprises a compact obtained by vulcanizing and forming 100 parts of silicone rubber of (A) 50 shore hardness containing dimethyl polysiloxane as a main component mixed with 0.5 part of peroxide as a vulcanizing agent, 8 parts of silicone oil having viscosity of 100000cSt, and 0.2 part of carbon black.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a syringe used for injecting an injection solution, and more particularly to a syringe used for low-speed precision injection of an injection solution.

[0002]

2. Description of the Related Art Conventionally, a synthetic resin syringe has been known as a disposable syringe. The syringe comprises an outer cylinder and a plunger that slides in close contact with the inner surface of the outer cylinder via a gasket fitted to the tip, and both the outer cylinder and the plunger are olefinic or styrene such as polypropylene or styrene. It is manufactured by injection molding from a series of resins.

The gasket fitted to the tip of the plunger is desired to have proper elasticity so as to be in close contact with the inner surface of the outer cylinder to prevent the leakage of the injection liquid and the inclusion of bubbles. Molded bodies made of synthetic rubber such as butadiene rubber, butyl rubber and isoprene rubber are used. In order to obtain smooth slidability, the gasket made of rubber is generally coated with silicone oil at the time of use.

However, when the above-mentioned syringe is used for low-speed precision injection of an injection solution, even if silicone oil is applied to the gasket, the load tends to fluctuate greatly and it may be difficult to slide sufficiently smoothly. There is a disadvantage that oil may be mixed in the injection solution.

In order to solve the above-mentioned inconvenience, it has been proposed to use silicone rubber having low hardness and flexibility for the gasket. According to the gasket made of the above-mentioned molded body of silicone rubber, when the gasket is fitted into the plunger, it can be slid in the outer cylinder without applying silicone oil, but the sliding is smooth enough to enable low-speed precision injection. There is no mobility.

Therefore, Japanese Patent Publication No. 60-57873 discloses a gasket obtained by swelling a silicone rubber molding by immersing it in silicone oil. According to the description of the above-mentioned publication, according to the gasket obtained by swelling the silicone rubber molded body with silicone oil, the silicone oil exuding on the rubber surface can provide appropriate lubricity with the container wall of the outer cylinder. ing.

However, it is difficult to control the amount of silicone oil exuding on the rubber surface with the gasket, and it cannot be said that the problem that the silicone oil may be mixed in the injection solution is sufficiently solved.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate such inconvenience and to provide a syringe capable of accurately injecting an injection liquid at a low speed and less containing a lubricant in the injection liquid. And

[0009]

According to the study by the present inventor, the reason why the above-mentioned inconvenience occurs in the gasket described in the above publication is that the gasket is swollen by immersing the silicone rubber molding in silicone oil. Therefore, it was found that the silicone oil contained more silicone oil in a portion closer to the surface of the gasket in the silicone rubber molding.

Therefore, the syringe of the present invention is a syringe comprising an outer cylinder and a plunger slidably provided through a gasket fitted to the tip end and closely adhered to the inner surface of the outer cylinder. Is composed of a molded body of silicone rubber obtained by blending a lubricant and vulcanization molding.

The silicone rubber contains dimethylpolysiloxane or polydiorganosiloxane as a main component,
The Shore hardness (A) is preferably in the range of 30 to 70. When the Shore hardness (A) is less than 30, it is too flexible and deforms when sliding inside the outer cylinder, and the contact area becomes large, resulting in insufficient smoothness of sliding or leakage of injection liquid. May occur. Moreover, when the plunger is pulled out, the gasket may fall off from the tip of the plunger. Further, when the Shore hardness (A) exceeds 70, sufficient flexibility cannot be obtained and sliding smoothness becomes insufficient, and heat from sterilization and long-term storage may cause a restoring force of the gasket to cause an outer cylinder. The inner diameter of the tube may expand and cause leakage of the injection solution.

The above-mentioned molded body of silicone rubber is obtained by adding silicone oil as a lubricant to the silicone rubber, or
Those obtained by blending polytetrafluoroethylene (PTFE) powder and vulcanizing and molding can be suitably used.

When silicone oil is used as the lubricant, the silicone rubber has a viscosity of 1000-2.
00000 cSt, preferably 10,000 to 20,000
0 cSt of silicone oil is blended in the range of 0.1 to 30% by weight, preferably 1 to 10% by weight, and vulcanized and molded. Further, the silicone oil is preferably used in combination with polyethylene powder in order to adjust the hardness of the obtained molded product. In this case, the polyethylene oil having an average particle size of 1 to 50 μm is used in the range of 1 to 20% by weight together with the silicone oil. Are mixed and vulcanized and molded.

The viscosity of the silicone oil is 1000c
When it is less than St, the amount of silicone oil exuding from the gasket tends to be excessive, and 20,000 cSt
When it exceeds, it tends to be too small. Further, when the blending amount of the silicone oil is less than 0.1% by weight, the amount of the silicone oil that exudes tends to be too small, and when the blending amount exceeds 30% by weight, the hardness of the obtained silicone rubber becomes too low and the gasket becomes There is a risk that it will fall out of the tip of the plunger, and it will take time to mix it with the raw rubber, and workability will also deteriorate.

If the average particle diameter of the polyethylene powder is not within the above range, it may not be uniformly dispersed in the raw rubber. When the content of the polyethylene powder is less than 1% by weight, the hardness of the obtained molded article becomes low and the contact area becomes large when sliding in the outer cylinder, so that the smoothness of sliding becomes insufficient. , When removing the plunger, the gasket may fall out from the tip of the plunger. Further, when the blending amount of the polyethylene powder exceeds 20% by weight, the polyethylene powder may float on the surface of the obtained molded product, and the workability at the time of blending with the raw rubber decreases.

When PTFE powder is used as the lubricant, 1 to 1 of the PTFE powder having an average particle diameter of 0.5 to 100 μm is added to the silicone rubber, preferably one having a Shore hardness (A) of 40 to 60. It is compounded in a range of 20% by weight and vulcanization molded.

If the average particle diameter of the PTFE powder is not within the above range, it may not be uniformly dispersed in the raw rubber. The compounding amount of the PTFE powder is 1% by weight
If it is less than 20%, the smoothness of sliding of the obtained molded article may not be sufficient, and if it exceeds 20% by weight, workability in compounding with raw rubber may be deteriorated.

Further, the syringe of the present invention is a syringe comprising an outer cylinder and a plunger which slides in close contact with the inner surface of the outer cylinder via a gasket fitted to the tip, the gasket being silicone. A molded product obtained by laminating rubber or one or more kinds of silicone rubber obtained by vulcanizing and molding the above lubricant and vulcanizing and molding the rubber in order of increasing flexibility from the side in close contact with the outer cylinder. ..

[0019]

[Function] According to the syringe of the present invention in which a molded product obtained by blending silicone oil with silicone rubber and vulcanization molding is used as a gasket, the silicone oil contained in the gasket exudes over time on the gasket surface. Therefore, the gasket smoothly slides in the outer cylinder while being fitted to the tip of the plunger. Since the silicone oil is blended before the vulcanization of the silicone rubber, it is uniformly dispersed and contained in the molded product obtained by vulcanization molding, and it is always sufficient to ensure the smoothness of sliding. Only a certain amount of silicone oil exudes and does not exude excessively. Therefore, the amount of silicone oil mixed in the injection solution is reduced.

According to the syringe of the present invention, which uses as a gasket a molded product obtained by blending silicone rubber with polyethylene powder together with silicone oil, according to the syringe of the present invention, the hardness of the resulting molded product is controlled. The gasket prevents the gasket from falling off the plunger tip even when the plunger is pulled out.

According to the syringe of the present invention in which a molded product obtained by blending PTFE powder with silicone rubber and vulcanization molding is used as a gasket, the PTFE contained in the gasket is used.
E powder is uniformly dispersed on the gasket surface. The P
Since TFE is a substance having a low frictional resistance, the gasket slides smoothly in the outer cylinder in a state of being fitted to the tip of the plunger. Since the PTFE powder is blended before the vulcanization of the silicone rubber, it is uniformly dispersed in the molded product obtained by vulcanization molding and on the surface thereof, and the amount of dispersion on the gasket surface determines the smoothness of sliding. There is no excess, just enough to secure. Therefore, PT mixed in the injection solution
The amount of FE is reduced.

A silicone rubber or one or more silicone rubbers obtained by vulcanizing and molding the above lubricant and laminating the silicone rubber in the order of higher flexibility from the side in close contact with the outer cylinder. According to the syringe of the present invention as a gasket, since the layer that adheres to the outer cylinder of the gasket is composed of any of the above-mentioned silicone rubbers containing a lubricant, smoothness of sliding is ensured and injection is performed. The amount of lubricant mixed in the liquid is reduced. The layer in contact with the plunger has a higher hardness than the silicone rubber that does not contain a lubricant or one of the above-mentioned silicone rubbers that contains a lubricant, which constitutes the layer that adheres to the outer cylinder. Since it is made of silicone rubber, the gasket does not easily fall off the plunger tip when the plunger is pulled out.

[0023]

Embodiment 1 Next, the syringe of the present invention will be described in more detail with reference to the accompanying drawings. FIG. 1 is an explanatory sectional view showing an example of a syringe according to the present invention.

The syringe of this embodiment has an internal volume of 25 ml, has an outer cylinder 1 and a plunger 2 as shown in FIG.
A gasket 3 is fitted on the tip of the plunger 2. The gasket 3 is in close contact with the inner wall of the outer cylinder 1, and the plunger 2 is slidable on the inner surface of the outer cylinder 1 via the gasket 3.

In the gasket 3, 100 parts of silicone rubber containing dimethylpolysiloxane as a main component and having a Shore hardness (A) of 50, 0.5 part of peroxide as a vulcanizing agent, and 8 parts of silicone oil having a viscosity of 100,000 cSt, A molded body obtained by blending 0.2 part of carbon black and vulcanization molding was used.

A 21 G intravenous needle was attached to the syringe, and distilled water was discharged at an infusion rate of 10 ml / h to test the smoothness of sliding. The fluctuation of the load applied to the plunger 2 in the test is shown in FIG. 2, and the discharge amount every 10 seconds is shown in FIG. 3 (a).

As is apparent from FIGS. 2 and 3 (a),
In the syringe of this embodiment, there is almost no change in load and the discharge amount is almost constant. Therefore, in the syringe of the present embodiment, it is clear that the plunger 2 is smoothly slid by the gasket 3 and can be advantageously used for low-speed precision injection of an injection solution.

In the syringe of this embodiment, the amount of silicone oil contained in the discharge liquid was measured by the method of measuring the number of fine particles to find that it was 55 as fine particles of 1 to 40 μm.
00, which is reduced to 10 to 30% of the silicone oil contained in the liquid discharged from the syringe of the comparative example described later.

The number of fine particles was measured as follows. First, as a blank test, a prescribed amount of dust-free water was injected into a syringe that did not use silicone oil at all, and the mixture was shaken several times to extract a prescribed test liquid. 27 when counted
It was 00. The number of fine particles includes the number of minute bubbles that cannot be visually observed. Next, dust-free water was injected into the syringe of this example, the number of fine particles was counted in the same manner as above, and the difference from the blank was taken as the amount of silicone oil contained in the discharge liquid.

[0030]

COMPARATIVE EXAMPLE 1 A syringe having the same structure as the syringe shown in FIG. 1, but using a conventional molded body made of butadiene rubber for the gasket 3 and applying silicone oil to the inner wall of the outer cylinder 1 was prepared.

Using the syringe, the smoothness of sliding was tested in the same manner as in Example 1. Liquid velocity 1 in the test
Fig. 2 shows the fluctuation of the load applied to the plunger 2 when the distilled water was discharged at 0 ml / h, and Fig. 3 shows the discharge amount every 10 seconds.
It shows in (b).

As is apparent from FIGS. 2 and 3 (b),
In the syringe of this comparative example, the load fluctuates continuously,
The discharge rate is constantly changing as the load changes. Therefore, it is clear that the conventional gasket which is used by applying silicone oil to the inner wall of the outer cylinder 1 cannot obtain the sliding smoothness suitable for the low-speed precision injection of the injection liquid.

In the syringe of this comparative example, the amount of silicone oil contained in the discharge liquid was measured by the method of measuring the number of fine particles in the same manner as in Example 1.
It was 45,000 as fine particles of m.

[0034]

Example 2 In the syringe shown in FIG. 1, the gasket 3 was composed of 100 parts of silicone rubber containing dimethylpolysiloxane as a main component and having a Shore hardness (A) of 50, and 0.5 parts of a peroxide as a vulcanizing agent. A molded product obtained by mixing 10 parts of PTFE powder having an average particle diameter of 1 μm and 0.2 part of carbon black and vulcanizing and molding was used.

When the smoothness of sliding was tested using the above-mentioned syringe in the same manner as in Example 1, the same result as that of the syringe in Example 1 was obtained.

[0036]

Example 3 In the syringe shown in FIG. 1, the gasket 3 was composed of 100 parts of a silicone rubber containing dimethylpolysiloxane as a main component and having a Shore hardness (A) of 50, and 0.5 parts of a peroxide as a vulcanizing agent. A molded product obtained by mixing 8 parts of silicone oil having a viscosity of 100,000 cSt, 15 parts of polyethylene powder having an average particle diameter of 5 μm and 1.5 parts of carbon black and vulcanizing and molding was used.

When the smoothness of sliding was tested by using the above-mentioned syringe in the same manner as in Example 1, the smoothness was slightly lowered as compared with the syringe of Example 1, but there was no problem in practical use. Also, when pulling out the plunger 2, the gasket 3
Became difficult to fall off from the tip of the plunger 2.

[0038]

Example 4 In the syringe shown in FIG. 1, the gasket 3 was a molded body formed by laminating two kinds of silicone rubbers having different hardnesses.

FIG. 4 is an explanatory sectional view showing the structure of the gasket 3 used in this embodiment. As shown in FIG. 4, the gasket 3 used in this embodiment has a surface layer 4 made of a highly flexible silicone rubber and an inner surface layer 5 in contact with the plunger 2 made of a silicone rubber having a hardness higher than that of the silicone rubber 4. ing.

The surface layer 4 is made of dimethylpolysiloxane as a main component and has a Shore hardness (A) of 40.
Part, 0.5 part of peroxide as a vulcanizing agent, viscosity of 10000
The inner surface layer 5 is composed of a molded product obtained by vulcanizing and molding 8 parts of 0 cSt silicone oil and 0.2 part of carbon black, and the inner surface layer 5 is a silicone having a Shore hardness (A) of 60 as a main component. 100 parts of rubber, 0.5 part of peroxide as a vulcanizing agent, 1.5 of carbon black
And a lubricant-free molded product obtained by vulcanizing and molding parts.

When the smoothness of sliding was tested using the above-mentioned syringe in the same manner as in Example 1, the same result as that of the syringe in Example 1 was obtained. Further, the gasket 3 is securely fixed to the tip of the plunger 2, and the gasket 3 is less likely to fall off the tip of the plunger 2 when the plunger 2 is pulled out.

[0042]

As is apparent from the above, according to the syringe of the present invention, which uses a gasket made of a silicone rubber molded product obtained by blending silicone oil or PTFE as a lubricant and then vulcanizing and molding the mixture. Since the lubricant is contained in the gasket in a state of being uniformly dispersed, the plunger can be smoothly slid by the gasket and the amount of the lubricant mixed in the injection solution can be reduced. Can be done.

Further, in the syringe of the present invention which uses a gasket made of a silicone rubber molding obtained by blending polyethylene powder with silicone oil and then vulcanization molding, the hardness of the molding obtained by the polyethylene powder is adjusted. Therefore, when the plunger is pulled out, the gasket does not easily come off from the tip of the plunger.

Further, according to the syringe of the present invention, which uses a gasket composed of a molded body in which plural kinds of silicone rubbers having different hardnesses are laminated in the order of higher flexibility from the side of closely contacting the outer cylinder, the flexibility of the surface layer is improved. The high silicone rubber allows the plunger to slide smoothly, and the gasket that is firmly fixed to the tip of the plunger by the silicone rubber having a hardness higher than the surface layer of the layer contacting the plunger pulls out the plunger. When doing so, it is possible to make it difficult for the gasket to fall off the tip of the plunger.

Therefore, the syringe of the present invention can be advantageously used for low-speed precision injection of an injection solution.

[Brief description of drawings]

FIG. 1 is an explanatory sectional view showing an example of a syringe according to the present invention.

FIG. 2 is a graph showing fluctuations in load on the plunger during low-speed precision injection of an injection solution in the syringes of Example 1 and Comparative Example 1.

FIG. 3 is a graph showing the discharge amount for every 10 seconds during low-speed precision injection of the injection liquid in the syringes of Example 1 and Comparative Example 1.

FIG. 4 is an explanatory cross-sectional view showing one structural example of a gasket used for the syringe according to the present invention.

[Explanation of symbols]

 1 ... Outer cylinder, 2 ... Plunger, 3 ... Gasket.

Claims (5)

[Claims] 1. A syringe comprising an outer cylinder and a plunger slidably provided through a gasket which is fitted to the distal end and adheres to the inner surface of the outer cylinder, the gasket containing a lubricant. A syringe comprising a molded body of silicone rubber obtained by vulcanization molding. 2. The silicone rubber molded product is obtained by vulcanizing and molding a silicone oil having a viscosity of 1,000 to 200,000 cSt as a lubricant in a range of 0.1 to 30% by weight. Item 1. The syringe according to item 1. 3. The silicone rubber molding is obtained by further vulcanizing and molding polyethylene powder having an average particle diameter of 1 to 50 μm in an amount of 1 to 20% by weight. The syringe described. 4. A silicone rubber molded product obtained by vulcanizing and molding polytetrafluoroethylene powder having an average particle size of 0.5 to 100 μm as a lubricant in a range of 1 to 20% by weight. The syringe according to claim 1, wherein: 5. A syringe comprising an outer cylinder and a plunger that slides in close contact with the inner surface of the outer cylinder via a gasket fitted at the tip, wherein the gasket comprises silicone rubber or a lubricant. A syringe characterized by being a molded body obtained by laminating one or more kinds of silicone rubber obtained by blending and vulcanization molding in order of increasing flexibility from the side in close contact with the outer cylinder.