JPH053318B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a syringe and a method for manufacturing the same.
More specifically, a piston is used in which a slider made of thermoplastic elastomer is integrally provided on a piston body made of hard plastic, and the piston body is formed on most of the liquid contact surface of the piston. The present invention relates to a syringe that can reduce the amount of eluate by disposing a hard plastic and can be manufactured economically, and a method for manufacturing the same. [Background of the Invention] Conventionally, syringes for dispensing or injecting liquid into the human body for the purpose of diagnosis or treatment have been widely employed in the medical field. The syringe generally includes an outer cylinder made of glass or hard plastic, a pusher that is slidably fitted into the outer cylinder, and a pusher that is attached to the pusher and attached to the inner wall of the outer cylinder. It basically consists of a piston that comes into sliding contact. In this case, the piston is formed of a rubber material or a thermoplastic elastomer and then incorporated into the pusher. In fact, since the rubber materials are relatively expensive, thermoplastic elastomers have come to be used. Furthermore, in order to reduce the manufacturing cost of the syringe itself, a syringe has been devised in which a piston and pusher made of the thermoplastic elastomer are integrally molded (see Japanese Patent Laid-Open No. 58-67265). However, in the syringe disclosed in this patent publication, since the entire piston is made of thermoplastic elastomer, there is a concern that eluates may appear over time. That is, thermoplastic elastomers have higher dissolution properties than hard plastics and the like. For this reason, like the syringe mentioned above, especially those whose entire liquid contact surface is made of thermoplastic elastomer, they are substantially exposed to the chemical liquid etc. injected into the syringe, and the thermoplastic elastomer It has been pointed out that there is a concern that a considerable amount of eluate may be mixed into the drug solution. Moreover, the piston itself of the syringe has a considerable thickness, and therefore, the manufacturing cost cannot be reduced as desired. This is because if the piston is thick, the cooling time will be long when the piston is obtained by injection molding, and the production process cannot be carried out very efficiently. Further, since the piston is thick, when the pusher is pushed, a difference occurs between the amount of deformation of the pusher and the amount of deformation of the piston. That is, the pusher is made of a hard plastic with relatively high rigidity, while the thermoplastic elastomer forming the piston has low rigidity. Furthermore, since the piston is in liquid-tight contact with the outer cylinder, when the pusher is displaced, the piston is once bent and then displaced. Therefore, it has been pointed out that there is a drawback that the followability of the piston to the pusher is substantially deteriorated. Therefore, a syringe was devised in which the piston was made of the above-mentioned thermoplastic elastomer and the wall was made as thin as possible (Jikkosho No. 57-
(See No. 46983). In the syringe according to this prior art, a pair of piston supports for the pusher is provided, and a piston made of thermoplastic elastomer is disposed so as to cover the piston support, thereby making the piston itself thinner and making it possible for the piston to support the pusher. Efforts are being made to improve followability. However, in the above-mentioned piston, like the piston according to Japanese Patent Application Laid-Open No. 58-67265 mentioned above,
The entire liquid contact surface is made of thermoplastic elastomer. Therefore, the concern that eluate may be mixed into the medicinal solution injected into the syringe has not yet been eliminated. [Object of the Invention] The present invention has been made in view of the above, and provides a piston constituting a syringe with a piston body made of hard plastic, and a slide that engages with the piston body and made of thermoplastic elastomer. A hard plastic forming the piston body is disposed on the liquid contact surface of the piston that comes into contact with the chemical liquid, etc., and when manufacturing the piston, the tip of the piston body is A flow path is provided that extends radially in the outer circumferential direction from the piston body, and the thermoplastic elastomer is caused to flow into the outer peripheral portion of the piston body through the flow path and solidify, thereby forming a thin and uniform slider. It is an object of the present invention to provide a syringe and a method for manufacturing the syringe, which can thereby reduce eluate from the piston body as much as possible. [Means for achieving the object] In order to achieve the above object, the present invention provides a syringe for injecting liquid into or suctioning liquid from the human body, which has a cylindrical shape. a cylinder; a pusher that enters the outer cylinder and has a cylindrical support pair formed at its tip; a cylindrical part that fits onto the tip of the support pair of the pusher; and a tip of the cylindrical part. a piston body formed of hardened plastic, the conical portion integrally projecting from the conical portion and having at least one groove defined in the conical portion oriented circumferentially from the apex of the conical portion; a cylindrical body that fits onto the cylindrical portion of the piston body;
and at least one rib formed integrally with the cylindrical body in the groove of the piston body, the conical part of the piston body being exposed to the outside from the space defined by the tip of the cylindrical body and the rib. a slider made of a thermoplastic elastomer that is exposed to the outside, and the conical part, the ribs, and the tip of the cylindrical body that are exposed to the outside constitute a liquid contact surface for the liquid filled in the outer cylinder. It is characterized by The present invention also provides a method for manufacturing a syringe for injecting a liquid into a human body or suctioning a liquid from a human body, in which a piston body is formed from a central portion of the tip of the piston body. a first step of defining a plurality of grooves oriented toward the outer periphery; a second step of arranging the piston body in a mold; It is characterized by comprising a third step of forming a slider by flowing into the outer circumferential surface side through the groove. [Embodiments] Next, preferred embodiments of the method for producing a syringe according to the present invention in relation to a syringe obtained using the method will be described in detail with reference to the accompanying drawings. In FIG. 1, reference numeral 10 indicates a syringe according to the present invention, and the syringe 10 includes an outer cylinder 12. As shown in FIG. The outer cylinder 12 has a substantially cylindrical shape, and one end thereof has a reduced diameter, and a distal end 16 defining a through hole 14.
A hollow injection needle (not shown) or the like can be attached to the tube. On the other hand, a flange 18 is provided on the other end side of the outer cylinder 12.
A pusher 20 is provided inside the pusher 20 from the other end.
enters. As shown in FIG. 2, the pusher 20 is
It includes plate members 22 formed to intersect with each other at 90° offset, flanges 24 and 26 formed at their respective ends, and a support member 28 fixed to one of the flanges 24. The support body 28 has a substantially cylindrical shape with a blunt tip, and has an annular protrusion 30 formed on its peripheral wall. A piston 32 is engaged with the tip of the pusher 20 . In this case, the piston 32 can be displaced within the outer cylinder 12 in the direction of the arrow _A1 or _A2 by pushing or pulling the pusher 20. The piston 32 substantially consists of a piston body 34 that engages with the pusher 20, and a relatively thin slider 36 that fits on the outside of the piston body 34. The piston body 34 is formed of a hard plastic with little eluate, such as polypropylene, polyethylene, polystyrene, polycarbonate, polyethylene terephthalate, or polymetal methacrylate. The piston main body 34 includes a cylindrical portion 38 that fits onto the support body 28 constituting the pusher 20, and a conical portion 40 that is formed continuously with the cylindrical portion 38. Said cylindrical part 3
A circumferential groove 42 is defined on the inner surface of the circumferential groove 4 .
The annular protrusion 30 of the support body 28 is fitted into the piston body 2, and the piston body 34 is engaged with the pusher 20. Furthermore, a plurality of grooves 44a to 44c are defined in the conical portion 40, oriented toward the outer circumference from the center and radially offset by 120° (see FIG. 3). Next, the slider 36 will be explained. The slider 36 is formed of a thermoplastic elastomer (e.g., polyolefin elastomer, fluororesin elastomer, ethylene-propylene copolymer elastomer, styrene elastomer, vinyl chloride elastomer, urethane elastomer, polyester elastomer, etc.). . The slider 36 is formed integrally with a cylindrical body that fits over the outer circumferential wall surface of the cylindrical portion 38 of the piston body 34 and the tip of this cylindrical body, and is formed integrally with the grooves 44a to 44c of the conical portion 40. Ribs 46a to 4 that fit into the
It has 6c. Further, the slider 36 has seal portions 48 and 5 that abut against the inner circumferential wall surface of the outer cylinder 12.
0 is formed as a bulge. In this case, the area of the liquid contacting surface of the piston body 34 is formed to be substantially larger than the area of the liquid contacting surface of the slider 36 in the pushing direction of the pusher 20. That is, as can be understood from FIG. 3, the cylindrical tip of the slider 36 and the rib 4
The piston body 34 is exposed to the outside from the space defined by the cylindrical body tip and the ribs 46a to 46c, rather than the liquid contact area where the parts 6a to 46c merge.
The area of the tip is large.
This is to reduce the area of the slider 36 that comes in contact with the chemical liquid as much as possible when the piston 32 presses the chemical liquid etc. inside the outer cylinder 12 for reasons that will be described later. The cylinder according to the present invention is basically constructed as described above, and the manufacturing method thereof will be explained next. First, the outer cylinder 12 and the pusher 20 are formed in advance by injection molding or the like, and the piston 32 is manufactured. That is, the piston bodies 34 constituting the piston 32 are separately formed by injection molding. Next, as shown in FIG. 4, the piston body 34 is fitted onto the protrusion 52a of the first mold 52, and the first mold 52 and the second mold 54 are engaged. Thereby, a cavity 56 is defined in the vicinity of the piston body 34. Therefore,
Molten thermoplastic elastomer is filled into the cavity 56 from a passage 58 formed in the second mold 54 . In this case, the molten metal flows into the center of the conical portion 40 constituting the piston body 34 through the passage 58, and flows from the center into the grooves 44a to 44.
It reaches the outer peripheral part of the cylindrical part 38 via c. After a predetermined period of time has elapsed and solidified, the second mold 54 is separated from the first mold 52 and the piston body 34 is removed from the first mold 52. That is, the piston 32 is manufactured thereby. Next, the piston 32 is engaged with one end of the pusher 20, and the piston 32 and the tip sides of the pusher 20 are inserted into the outer cylinder 12 to assemble the syringe 10. In this manner, by using the syringe manufacturing method according to this embodiment, it is possible to form the slider 36 made of thermoplastic elastomer substantially uniformly on the outer peripheral surface of the piston body 34.
That is, a plurality of grooves 44a to 44c are formed in the conical portion 40 of the piston body 34, extending toward the outer circumference and being offset from each other by approximately 120 degrees. Therefore, by introducing the molten metal into the center of the conical part 40, the molten metal uniformly flows into the outer peripheral surface of the cylindrical part 38 through the grooves 44a to 44c, and as a result, the slider 36 is considerably moved. The effect is that it becomes possible to make the wall thinner. Next, the functions and effects of the syringe according to the present invention will be explained. First, a hollow injection needle (not shown) is attached to one end side of the outer cylinder 12 constituting the syringe 10, and the pusher 10 is displaced in the direction of arrow _A2 , thereby causing a drop inside the outer cylinder 12. Inhale the drug solution. Next, the injection needle is inserted into a patient, etc., and the medicinal solution is injected into the patient. That is, by pushing the pusher 20, the pusher 20
and the piston 32 attached to its tip are indicated by arrows.
_A The drug solution is injected into the patient through the injection needle. In this case, according to the syringe according to this embodiment, since the slider 36 formed of thermoplastic elastomer with relatively low rigidity is made as thin as possible, the piston 32
It is possible for itself to be smoothly slid and displaced. Therefore, the piston 32 with respect to the displacement of the pusher 20
It has extremely good followability for sliding movement, and the injection of chemical liquid can be performed as desired. This was confirmed by the water droplet ejection experiment described below. That is, in this water droplet discharge experiment, first, water was sucked into the syringe 10 according to the present invention and the syringe according to the prior art, respectively, and the cylinder 10 and the syringe according to the prior art were respectively attached to a syringe pump. Further, an infusion set consisting of a tube and a needle attached to the tip of the tube was attached to the tip of the cylinder, and the needle was held in a vertically downward direction. Next, the cylinder pump was set to a discharge rate of 1 ml per hour, and the discharge interval of water droplets dripping from the needle tip of the infusion set was measured. In this case, the infusion set is one in which 1 ml of water is divided into 60 drops and discharged. Therefore, if the syringe pump discharges the water in the syringe 10 and the syringe according to the prior art at a rate of 1 ml per hour, it is accurate to One drop is added per minute. The results of the above experiment are shown in FIGS. 5a and 5b. FIG. 5a shows the experimental results of a syringe according to the prior art, in which a pulse signal is generated every time one drop (1/60 ml) of water is dropped from an infusion set, so that the syringe can be used at a predetermined time interval. This is a chart showing the number of drops. Also, Figure 5b
1 is a time chart showing the experimental results of measuring the number of drops of water from the syringe 10 according to the present invention at predetermined time intervals. This confirms that the syringe 10 according to the present invention regularly drips water at a rate of one drop per minute. On the other hand, it was confirmed from FIG. 5a that in the syringe according to the prior art, there was a large variation in the drop interval. Therefore, it has been found that the syringe 10 according to the present invention is capable of discharging medicinal liquids more accurately than the syringes according to the prior art. Furthermore, since the syringe 10 according to the present invention is configured such that the piston body made of hard plastic with a small amount of eluate is disposed on the liquid contact surface over as wide an area as possible, the syringe 10 is inhaled into the syringe 10. An effect was also obtained in that the amount of substances eluted into the drug solution over time was significantly reduced compared to the syringe according to the prior art. The above-mentioned effects were made clear by a test on eluates using a disposable syringe. That is,
In this test, water was absorbed into the syringe 10 and the syringe according to the prior art up to the maximum scale position, the water was heated at 70° C. for 30 minutes, and 50 ml of water in each of the syringes was sampled. The following tests were conducted using this water as a test liquid. First, each test liquid and blank test liquid were
20 ml were taken out and 1 ml of potassium chloride solution was added to them. Then, measure the PH of each of the above test and blank test solutions, and
The difference in PH was measured. In addition, 10 ml of each of the test solutions described above was placed in an Erlenmeyer flask, 20 ml of potassium permanganate solution and 1 ml of dilute sulfuric acid were added, and the flasks were boiled for 3 minutes. After cooling the boiled test liquid, it is converted into potassium iodide.
0.1 g and 5 drops of starch test solution were added and titrated with sodium thiosulfate solution. When the above operation was carried out using 10 ml of water instead of the test liquid, the difference in the amount of potassium permanganate solution consumed between the test liquid and water was measured. Furthermore, 10 ml of the above-mentioned test solution was evaporated to dryness in a water bath, and the amount of the residue after drying at 105° C. for 1 hour was measured. The above test results are shown in Table 1.

[Table] As described above, all the values of the test solution from the syringe 10 were smaller than those from the syringe according to the conventional technology, and therefore, it was found that the eluate from the syringe 10 was extremely small. . Next, other embodiments of the syringe according to the present invention will be described. In addition, in this embodiment,
Components that are the same as those in the first embodiment described above are given the same reference numerals, and therefore detailed description thereof will be omitted. That is, the syringe 10a according to this embodiment
As shown in FIG. 6, the piston body 60 includes a piston body 60 whose one end side enters the outer cylinder 12, and the other end side of the piston body 60 projects outward from the outer cylinder 12 and functions as the pusher 20. achieve. In other words, the piston body 60 is formed integrally with the pusher. In this case, the slider 36 engages with one end of the piston body 60. Note that a groove 62 is provided at one end of the piston body 60, similar to the grooves 44a to 44c of the piston body 34 according to the first embodiment.
is formed, and a portion of the slider 36 engages with this groove 62. According to the syringe 10a configured in this way, the syringe 10 according to the first embodiment described above
Not only can almost the same effect be obtained, but since the piston body 60 is integrally formed with the pusher 20, the manufacturing process can be simplified, the manufacturing cost can be further reduced, and the surface in contact with liquid can be reduced. The effect is that the amount of eluates is extremely small. [Effects of the Invention] As described above, according to the present invention, in a syringe for injecting and dispensing liquid into and out of a human body cylinder for the purpose of diagnosis and treatment, the piston constituting the syringe is relatively free from eluate. It consists of a piston body made of a small amount of hard plastic, and a slider made of thermoplastic elastomer that engages with the piston body and slidably abuts on the outer cylinder constituting the syringe. Furthermore, since the liquid contact surface of the piston includes the conical portion of the piston body made of hard plastic with as little eluate as possible, the amount of eluate in the chemical solution can be reduced. Further, if the area of the liquid contacting surface of the conical part is larger than the area of the liquid contacting surface of the locking part of the slider, the amount of eluate can be further reduced. Furthermore, when manufacturing the piston, a piston body having grooves extending radially from the center is formed in advance, and then molten thermoplastic elastomer is injected into the center of the piston body to form the notch. A slider is formed on the outer circumference of the piston body through the piston body. Therefore, the slider can be made extremely thin and uniform. As a result, according to the syringe according to the present invention, it is possible to accurately inject a predetermined amount of liquid medicine. Furthermore, since the slider formed of the thermoplastic elastomer is made thinner, the amount of the thermoplastic elastomer used can be reduced, and the cooling time in the manufacturing process can be shortened to further reduce the manufacturing cost of the syringe. This has the advantage of being possible. Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and changes in design can be made without departing from the gist of the present invention. Of course.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional explanatory diagram of a syringe according to the present invention,
Fig. 2 is an exploded perspective view of the syringe shown in Fig. 1, Fig. 3 is an end view of a piston constituting the syringe shown in Fig. 1, and Fig. 4 explains a method for manufacturing the piston shown in Fig. 3. FIGS. 5a and 5b are partially omitted cross-sectional explanatory views of a mold for molding and a piston formed by the mold, and show the relationship between the droplet interval and the time in a water droplet ejection experiment of a syringe according to the prior art and a syringe according to the present invention. The time chart shown in FIG. 6 is a partially omitted cross-sectional explanatory view of another embodiment of the syringe according to the present invention. 10, 10a...Syringe, 12...Outer tube, 2
0... Pusher, 28... Support, 32... Piston, 34... Piston body, 36... Slider, 5
2,54...Mold.

Claims (1)

[Scope of Claims] 1. A ring for injecting liquid into or suctioning liquid from the human body, etc., comprising: a cylindrical outer cylinder; It consists of a pusher on which a cylindrical support is formed, a cylindrical part that fits onto the tip of the support of the pusher, and a conical part integrally formed to protrude from the tip of the cylindrical part, a piston body formed of hardened plastic, the conical portion having at least one groove defined in a circumferential direction from the apex of the cone; a cylindrical body that fits over the cylindrical portion of the piston body;
at least one rib that is integrally formed with the cylinder and that fits into a groove in the piston body; a slider made of a thermoplastic elastomer whose portion is exposed to the outside, and the contact surface of the liquid filled in the outer cylinder is formed by the conical portion, the rib, and the tip of the cylinder body exposed to the outside. A syringe comprising: 2. The syringe according to claim 1, wherein the contact area of the conical portion exposed to the outside of the piston body is larger than the contact area of the cylinder and ribs of the slider. . 3. In the syringe according to claim 1 or 2, the groove of the conical portion of the piston body is approximately
A syringe characterized in that the slider has three ribs that are offset by approximately 120° and fit into each of the grooves. 4. A method of manufacturing a syringe for injecting liquid into a human body or suctioning a liquid from a human body, etc., in which a plurality of syringes oriented from the center of the tip of the piston toward the outer circumference when forming the piston body are used. a first step of defining a groove, a second step of arranging the piston body in a mold, and a step of introducing a molten metal made of thermoplastic material from the center of the piston body through the groove to the outer circumference of the piston body. A method for manufacturing a syringe, comprising a third step of forming a slider by flowing into the surface side. 5. In the method described in claim 4,
A method for manufacturing a syringe, wherein the thermoplastic material is a thermoplastic elastomer.