JP2003180832A - Syringe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfy slidability and hermeticity by a simple shape. <P>SOLUTION: A gasket 5 is composed of a polypropylene resin, polyethylene resin, cyclic polyolefinic resin, etc., and collars 5a to 5c touching the inner wall surface of a barrel are formed. The gasket 5 is formed to a large diameter of 0.02 to 0.15 mm with respect to the inner diameter of the barrel 2 and is so formed that the force required for sliding of the gasket 5 attains ≤25 N. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a syringe, and more specifically, polypropylene resin, polyethylene resin,
The present invention relates to a syringe having a gasket made of a hard resin such as a fluororesin, a cyclic polyolefin resin, and a polycarbonate resin.

[0002]

2. Description of the Related Art As is well known, a conventional syringe is mainly composed of a barrel for containing a liquid such as a drug solution and a piston reciprocally inserted into the barrel. And a gasket that is attached to the tip of the piston body by screwing or the like and that slides on the inner wall surface of the barrel while maintaining airtightness.

Further, as the material of the barrel, it is known at present that a cyclic olefin resin is preferable from the viewpoint of chemical resistance and heat resistance. On the other hand, the gasket must slide while maintaining airtightness with the inner wall surface of the barrel, and is therefore made of an elastomer such as butyl rubber.

[0004]

However, such an elastomer contains many additives such as a plasticizer, a cross-linking agent and a pigment, and may be eluted in the chemical liquid filled in the barrel, which is complicated. A washing step was needed.

Another problem is that the gasket made of elastomer must be separated and discarded.

Furthermore, the elastomer (particularly butyl rubber) is difficult to slide on the inner surface of the barrel, and it has been necessary to apply a lubricant such as silicone oil to the inner surface of the barrel in order to reduce sliding resistance. In particular, when a lubricant is used, there is a problem that the sliding resistance becomes high after being left for a long time.

Further, when the gasket is formed of an elastomer, it is difficult to obtain dimensional stability due to the manufacturing method.

Therefore, the applicant of the present invention has previously filed Japanese Patent Application No. 2000-1.
In No. 85644, the gasket material is made of resin as well as the barrel material in order to eliminate the washing step and improve dimensional accuracy and stability, and also has good airtightness, slidability, and ease of installation in the barrel. I proposed a syringe that

However, the syringe according to this proposal has a very complicated shape in order to maintain the airtightness.

[0010] Therefore, a main object of the present invention is to provide a syringe satisfying both slidability and airtightness with a simple shape.

[0011]

The present invention which has solved the above-mentioned problems is as follows. <Invention of Claim 1> A barrel for containing a liquid and a piston reciprocally inserted into the barrel. The piston is attached to a piston body and a tip of the piston body. And a gasket that slides with respect to the inner wall surface of the barrel while keeping airtightness; the gasket is made of an inelastic resin, and contacts the inner peripheral surface of the barrel with the outer peripheral surface of the gasket. A plurality of flange portions are formed at intervals in the piston sliding direction, and the flange portions are configured to slide while maintaining airtightness with respect to the barrel inner peripheral surface, and the outer diameter of the gasket. Is 0.02-0.15 with respect to the barrel inner diameter
A syringe having a diameter of mm and configured so that the force required for sliding the piston is 25 N or less.

(Effect) As will be apparent from the examples described later, the outer diameter of the gasket is 0.0 with respect to the inner diameter of the barrel.
While making the gasket a hard non-elastic resin (meaning resin excluding elastomer) by making the diameter 2 to 0.15 mm large and the force (sliding resistance) required for sliding the piston to be 25 N or less. Also, it is possible to provide a syringe that satisfies both air tightness and slidability with a very simple structure.

<Invention of Claim 2> A lubricant is applied to the inner peripheral surface of the barrel, and three or more flange portions are provided at intervals in the sliding direction of the piston. The syringe according to claim 1, wherein all the intervals are different.

(Effect) When a lubricant is applied to the inner surface of the barrel, if the piston is inserted into the barrel and left for a long time, the lubricant on the inner surface of the barrel comes into contact with the lubricant before and after the flange. When the piston is pushed and then the piston is slid, the sliding resistance at the relevant portion becomes high.

However, according to the present invention, by making all the intervals of the collars different from each other, the number of the collars that simultaneously pass through the portion where the amount of lubricant is small is always one. Therefore, after inserting the piston into the barrel and leaving it for a long time. However, the sliding resistance is unlikely to increase.

<Invention of Claim 3> The peripheral edge portion of the collar portion is a thin wall portion contacting the inner peripheral surface of the barrel, and the base end portion excluding the peripheral edge portion is a thick wall portion. The thin portion is supported by a portion, and the barrel material, the gasket material, the presence or absence of the use of a lubricant, and the type thereof, so that the force required for sliding the piston is 25 N or less, The number of the collar portion, and the thickness of the thin portion,
The syringe according to claim 1 or 2, wherein a protrusion height of the thin portion with respect to the thick portion and a thickness of the thick portion are determined.

(Function and Effect) Such a form is particularly preferable for satisfying both airtightness and slidability.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below with reference to the embodiments shown in the accompanying drawings. FIG. 1 shows an embodiment of a syringe 1 according to the present invention. The syringe 1 is composed of a barrel 2 that contains a liquid such as a drug solution, and a piston 3 that is reciprocally inserted into the barrel 2. Of these, the piston 3 is a piston body portion 4.
And a resin gasket 5 which is attached to the tip of the piston body 4 by screwing or the like and slides on the inner wall surface of the barrel 2 while maintaining airtightness. Specifically, as shown in FIG. 2, flange portions 5a to 5c that contact the inner wall surface of the barrel are formed on the peripheral surface of the gasket 5.

In the present invention, the gasket 5 is made of inelastic resin. As the resin, a hard resin suitable for medical instruments such as polypropylene resin, polyethylene resin, fluororesin, cyclic polyolefin resin, and polycarbonate resin can be appropriately selected and used. In particular, a cyclic polyolefin resin is preferable from the viewpoint of chemical resistance and the like. By making the gasket 5 made of a hard resin as described above, not only the amount of the eluate eluted into the chemical solution is small and the cleaning process is unnecessary, but also a known molding method can be adopted, and the dimensional accuracy and stability It will be highly effective. The same material can be used for the material of the barrel 2.

Further, in the present invention, the outer diameter of the gasket 5 (outer diameter of the peripheral edge of the collar portion) is 0.02 to the inner diameter of the barrel 2.
The diameter is 0.15 mm. If the difference between the outer diameter of the gasket 5 and the inner diameter of the barrel 2 is less than 0.02 mm,
It is impossible to satisfy the air tightness, and 0.15 m
If it exceeds m, the sliding resistance becomes too large and the operability deteriorates. From this point of view in particular, the outer diameter of the gasket 5 is the barrel 2
The diameter is preferably 0.02 to 0.08 mm larger than the inner diameter.

Further, the present invention is constructed so that the force required for sliding the piston is 25 N or less. This requirement is
It can be satisfied by appropriately setting the combination of the materials of the barrel and the gasket 5, the presence or absence of a lubricant, the type thereof, the shape and number of the collar portions 5a to 5c, and the like.
The material of the gasket 5 is as described above, and can be appropriately selected from the viewpoint of sliding resistance with respect to the barrel material. Further, in the present invention, a lubricant such as silicone oil can be used in the final adjustment of the sliding resistance, if necessary, but it is preferable not to use it from the viewpoint of hygiene.

On the other hand, the flange portions 5a to 5 of the gasket 5
Regarding the shape and the number of c, various modifications are possible within a range satisfying the numerical range of the present invention, but the one in the illustrated example is particularly recommended. That is, in the illustrated example, the collar portion 5
The peripheral portions of a to 5c are thin-walled portions y that come into contact with the inner peripheral surface of the barrel 2, and the base end portion excluding this peripheral edge portion is a thick-walled portion x. It is shaped to be. The thinness of the thin portion y cannot be generally stated because it is necessary to consider the degree of bending depending on the hardness of the material, but it is 0.1 to 0.5 mm, and particularly 0.2 to 0.4 mm. Is preferred. Thus, by forming the peripheral edge portion y of the collar portions 5a to 5c to be thin, the contact area between the collar portions 5a to 5c and the inner surface of the barrel 2 can be reduced, and the contact resistance can be reduced. Moreover, the thin portion y can be slightly contracted in the radial direction, but is supported by the thick portion x, so that the airtightness can be sufficiently ensured. The state of the collar portion when the piston 4 is pushed into the barrel 2 is shown in FIG. 3, and the state of the collar portion when the piston 4 is pulled back is shown in FIG.

By providing a plurality of flanges 5a to 5c at predetermined intervals in the piston sliding direction as shown in the drawing, not only can liquid leakage be prevented by a multiple seal, but the piston 3 can slide. It will always be held parallel to the direction. The preferable number of flanges is 3 to 6. If the number of the collar portions 5a to 5c is too large, a lubricant is used to reduce the sliding resistance, and the thickness and the protruding height of the collar portions 5a to 5c impair the airtightness. It is not preferable because it may be necessary to make it thinner.

Further, as shown in the drawing, it is preferable that the thin-walled portion y of the front flange portion 5a is thicker than those of the proximal flange portions 5b and 5c. That is, since the tip flange portion 5a mainly plays a role of maintaining the airtightness of the gasket 5, it is necessary to make it sufficiently thick. On the other hand, since the flange portions 5b and 5c on the base end side mainly play a role of maintaining the parallel posture of the gasket 5, even if it is thinned, there is almost no influence on the airtightness of the gasket 5 as a whole. 5 has an advantage that the contact area between the inner surface of the barrel 5 and the inner surface of the barrel 2 is reduced and sliding resistance is reduced. In this case, the ratio of the thickness of the thin portion y of the tip flange portion 5a to the thin portion y of the flange portions 5b and 5c on the base end side is set so that the sliding resistance of the entire gasket is within the range of the present invention. However, it is preferably 1.5 to 2.0 times.

Further, as shown in the figure, the collar portion 5a at the tip is
It is desirable that the thin portion y forms a gasket front end surface, and the thick portion x is provided only in a portion extending from the gasket front end surface to the rear side of the thin portion y. This is because if there is a depression around the tip surface, the liquid separation from the gasket will be poor. On the other hand, since the flange portions 5b and 5c on the base end side mainly play a role of maintaining the parallel posture of the gasket 5 as described above, the thick portion x is provided on both front and rear sides of the thin portion y, and It is preferable that the thin portion y is configured to be indicated by the thick portion x in both the forward movement and the backward movement.

On the other hand, in the case of applying the lubricant to the inner peripheral surface of the barrel 2, if the piston 4 is inserted into the barrel 2 and left for a long time, the lubricant at the flange contacting portion on the inner surface of the barrel 2 will be the flange portion. There is a phenomenon that when the piston is pushed back and forth from 5a to 5c and then the piston is slid, the sliding resistance at the relevant portion becomes high. Therefore, as shown in the drawings, the collar portions 5a to 5c
It is preferable that all the mutual intervals are different. As a result, the collar portion 5a, which simultaneously passes through the portion where the amount of lubricant is small,
5c is always one piece, in other words, each collar 5a-5
Since the timing at which c passes through the portion where the amount of lubricant is small is shifted, the sliding resistance is unlikely to increase even after the piston 4 is inserted into the barrel 2 and left for a long time.

The preferable ranges of the shapes and the numbers of the collar portions 5a to 5c are summarized below. -Number of flanges: 3 to 6- Tip flange 5a Thin wall thickness t1: 0.5 to 0.7 mm Thin wall protruding height H: 0.1 to 0.5 mm (especially 0.3 to
0.4 mm) Thickness T1: 0.5 to 1.3 mm (especially 0.9 to
1.2 mm) -Base end side flange portions 5b, 5c Thin portion thickness t2: 0.1 to 0.4 mm Thin portion protruding height H: 0.1 to 0.5 mm (especially 0.3 to
0.4 mm) Thickness T2 of thick part: 1.2 to 2.0 mm (especially 1.4 to
1.8 mm)

<Others> The syringe of the present invention is suitable for use as a drug solution (or for medical use), but it can also be used for containing and delivering another liquid.

[0029]

EXAMPLE A large number of syringes having the same shape as that shown in FIGS. 1 and 2 (the number of flanges was three) were manufactured with the gaskets having different outer diameters, and the sliding resistance of the piston was measured. In all examples, the barrel was made of cyclic polyolefin resin and the gasket was made of polyethylene resin. Further, in all examples, the tip flange portion has a thin portion thickness t1 = 0.5 mm and a thin portion protruding height H =
0.35 mm, the thickness T1 of the thick portion is 1.1 mm, and the proximal end flange has a thin portion thickness t2 of 0.3 mm, a thin portion protruding height H of 0.35 mm, and a thickness of the thick portion. T2 = 1.6mm
And

As a result, as shown in FIG. 5, the sliding resistance begins to increase when the difference between the outer diameter of the gasket and the inner diameter of the barrel exceeds 0.08 mm, and becomes extremely large when the difference exceeds 0.15 mm. It was On the other hand, when the difference between the outer diameter of the gasket and the inner diameter of the barrel was less than 0.02 mm, the sliding resistance was small but an airtightness test was conducted, but sufficient airtightness was not ensured.

Further, when at least one or both of the barrel material and the gasket material were replaced with other resins such as polypropylene and the sliding resistance was measured in various combinations, in the case of the combination of the cyclic polyolefin and the polyethylene resin of the above example. The almost same tendency was confirmed.

[0032]

As described above, according to the present invention, the cleaning process can be omitted and the manufacturing process can be simplified while satisfying both the slidability and the airtightness with a simple shape.
By enabling smooth sliding without using a lubricant, it is possible to improve dimensional accuracy and stability, and thereby reduce costs.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a syringe according to the present invention.

FIG. 2 is a longitudinal sectional view of a main part of a piston according to the present invention.

FIG. 3 is a longitudinal cross-sectional view of a main part showing a state when a piston is pushed in.

FIG. 4 is a longitudinal cross-sectional view of a main part showing a state when a piston is pulled out.

FIG. 5 is a graph showing the results of sliding resistance measurement in Examples.

[Explanation of symbols]

1 ... Syringe, 2 ... Barrel, 3 ... Piston, 4 ... Piston body part, 5 ... Gasket, 5a-5c ... Collar part.

Claims (3)

[Claims] 1. A barrel containing a liquid, and a piston reciprocally inserted into the barrel, wherein the piston is attached to a piston body and a tip end of the piston body. A syringe comprising a gasket that slides while maintaining airtightness on the inner wall surface of the barrel; the gasket is made of an inelastic resin, and a flange portion that is in contact with the inner peripheral surface of the barrel is provided on the peripheral surface of the gasket. A plurality is formed at intervals in the piston sliding direction,
The flange is configured to slide on the inner peripheral surface of the barrel while maintaining airtightness, and the outer diameter of the gasket is 0.02 to the inner diameter of the barrel.
A syringe having a diameter of 0.15 mm and configured so that the force required for sliding the piston is 25 N or less. 2. A lubricant is applied to the inner peripheral surface of the barrel,
The syringe according to claim 1, wherein three or more flange portions are provided at intervals in the piston sliding direction, and the flange portions are all different in interval. 3. The flange portion has a peripheral edge portion that is a thin wall portion that abuts on the inner peripheral surface of the barrel, and a base end portion excluding the peripheral edge portion is a thick wall portion, and the thin wall portion that forms the thin wall portion. The material of the barrel, the material of the gasket, the presence or absence of the use of the lubricant, the type of the lubricant, the number of the flanges, and the like, so that the force required for sliding the piston is 25 N or less. The syringe according to claim 1 or 2, wherein a thickness of the thin portion, a protruding height of the thin portion with respect to the thick portion, and a thickness of the thick portion are defined.