WO2018083221A1

WO2018083221A1 - Plastic injection moulded plunger for a medical syringe and a medical syringe

Info

Publication number: WO2018083221A1
Application number: PCT/EP2017/078154
Authority: WO
Inventors: Ronny Prosper Elisabeth Vrijens; Norbert Haberland; An Vanheel; Raphael KÄLIN; Thomas Cuyvers
Original assignee: Datwyler Pharma Packaging International Nv
Priority date: 2016-11-04
Filing date: 2017-11-03
Publication date: 2018-05-11
Also published as: DE102017125703A1

Abstract

The invention relates to a plastic injection moulded plunger (3) for a medical syringe (1), wherein the plunger (3) comprises one or more sealing lips (17, 18, 19), and, in cross-section, a sealing lip (17, 18, 19) is furthermore angled toward the front or the rear in an advancement direction (r) for the discharge of liquid from the syringe (1) during use. In order to improve a plunger of the type in question, the invention proposes that the plunger (3) is produced in a plastic injection moulding process from a fluorine-based plastic material. In the case of a sealing lip (17) angled towards the front, a channel (20) can be formed with respect to a central region of the plunger, which channel, viewed in cross-section, projects radially beyond the largest plunger diameter (D', D''). The invention further relates to a medical syringe having a plunger in one of the specified embodiments.

Description

description

A plastic syringe made of a syringe for a medical syringe and a medical syringe

Field of engineering

The invention relates first to a produced by plastic injection syringe piston for a medical syringe and further medical syringe see a syringe with a piston, wherein the piston has one or more sealing lips, further wherein a sealing lip in cross-section to the front or to the rear is swept to a given for the application of liquid from the syringe in use feed direction.

State of the art

Pistons of the type in question are known. These find particular use in medical syringes for administration or withdrawal of fluids to or from a patient, further, for example, as also preferred below, in syringes with a cylindrical body. Between the piston and the inner wall surface of the cylindrical syringe body, a liquid-tight seal is required. For this purpose it is known, on the piston, in particular with respect to the aligned in the feed direction

Longitudinal axis to form a circumferential sealing lip, which preferably cooperates with a radial excess over the inner diameter of the syringe barrel with the Wandungsinnenfläche the syringe barrel, this taking into account a low-friction displaceability of the piston in the cylinder. Conventionally, silicone oil is used to achieve low friction. The silicone oil can be applied both on the piston and alternatively or additionally on the inner surface of the cylinder. Further, it is known to align such a sealing lip in a cross section in which the longitudinal axis of the piston is a line in the discharge direction of the liquid swept forward. In this case, in a cross-section, a line penetrating the sealing lip in its direction extending outward from the piston outer wall encloses an acute angle of less than 90 °, in particular less than 75 °. In this regard, reference is made, for example, to EP 0 925 798 B1.

In addition, such a piston is known from DE

10 2005 003 516 B3, wherein the piston consists of an elastically deformable material and has circumferentially exposed by a longitudinal step-shaped configuration of the piston wall exposed sealing lips. EP 2 817 043 B1 relates to such a piston with back-swept sealing lips. From WO 01/60434 A1, a piston produced by two-component injection molding is known, which consists of a soft, elastomeric thermoplastic on the outside, forming a sealing lip which is swept to the front.

Summary of the invention

In view of the known prior art, the invention has the object to further improve a piston of the type in question. A possible solution to the problem is given according to a first inventive concept in a piston, in which it is geared to the fact that the piston in the plastic injection molding process is made of a fluorine-based plastic material. The fluorine-based plastic material offers advantages, in particular with regard to the frictional force between the piston and the inner wall surface of the syringe barrel. It is a thermoplastic material. The friction force is noticeably reduced in comparison to a piston made of an elastomer material. Moreover, in particular with regard to the use of such a piston in the medical field, a piston in the proposed embodiment is very inert.

The elasticity of the plastic, which is known from the plastic material selected over the elastomer material known from the prior art, such as, for example, rubber, is compensated by the design of the one or more sealing lips. At least the foremost sealing lip in the feed direction has a flexible behavior due to its swept orientation despite the comparatively hard plastic material.

Such a design of a piston makes it possible, the piston and / or the syringe barrel, with respect to its inner wall, free of

Silicone oil or other materials that contain silicone oil components to form further free of "baked on" silicone oil and other non-silicone oil-containing coatings A preferred feature is therefore that the piston and / or the syringe with which the piston interacts free from Silicone oil is formed.

The described arrowed alignment of the sealing lip results in a comparatively small contact area with the cylinder inner surface. This leads to a further reduction of the friction forces. A swept orientation does not necessarily require, in the context of the invention, an extension of the sealing lip which is rectilinear in cross section. It can also be a curved, extending forward or backward design or an angled shape tion of the sealing lip may be formed with a corresponding extending forward or rearward area.

In addition, a compensation of tolerances with respect to the inner diameter of the syringe barrel, for example, can be achieved by the preferably swept alignment of one or the sealing lips. Even with the selected plastic still results in a certain penetrability to compensate for a smaller inner diameter.

As a possible fluorine-based plastic materials in particular fluorine-containing (co) polymers are used, such as. ETFE (ethylene tetrafluoroethylene), which has a high radiation resistance, for example. In the course of radiation sterilization with gamma rays.

Furthermore, FEP (perfluoroethylene propylene copolymer) can also be used. This material is characterized by a high resistance to cleaning agents, moreover, behave by a favorable injection molding s.

Next is, for example, to mention THV, a terpolymer of

Tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride. This material is characterized by a certain flexibility and / or a relatively high tensile strength, in particular over the materials further exemplified in particular during the molding process and / or a relatively low yield strength, which is particularly advantageous when inserting the piston in the syringe barrel. Furthermore, this material is characterized by a relatively low flexural modulus. This property can also be helpful for better compensation of dimensional tolerances in the area of Syringe barrel inner surface. It can be achieved as a constant contact pressure value and thus a favorable sealing performance.

Another exemplary piston material is PVF (polyvinyl fluoride). This material is characterized by a relatively low oxygen permeability. This provides drug stability benefits over time. Due to the low oxygen permeability results in a lower tendency to oxidation.

Other exemplary materials within the meaning of the invention may also be perfluoroalkoxy polymers (PFA), polychlorotrifluoroethylene (PCTFE), ethylene enchlorotrifluoroethylene (ECTFE) and polyvinylidene fluoride (PVDF).

The higher the fluorine content in a polymer molecule, the higher its chemical resistance, solvent resistance, flame resistance and light stability. In addition, an improvement in the electrical properties, such as, for example, a low dielectric constant can be detected by a high proportion of fluorine. Also, an increased fluorine content lowers the coefficient of friction, raises the melting point and increases the thermal stability of the plastic part. The solubility of polymers in solvents decreases with the increase of fluorine content in the polymer molecule. Best properties are achieved when a polymer is completely fluorinated (eg perfluoroalkoxy polymers - PFA).

A further solution of the problem is given according to a further inventive idea in a piston, in which it is geared to that the piston is made in the plastic injection molding of a fluorine-based material and that the piston counter to the feed direction below a frontmost sealing lip largest Piston diameter forms and in that, viewed in a cross section, a channel formed by the swept-up sealing lip opposite a central region of the piston projects radially beyond the largest piston diameter.

The channel results from a gusset region between the piston section, on which the sealing lip is rooted, and an upper side of the piston

Sealing lip. The swept in cross-section alignment of the sealing lip and thus also the top of the sealing lip leads to a cross-section preferably V-shaped channel.

In a projection in the feed direction preferably extends a piston outer surface of the foremost in the feed direction below

Sealing lip adjoining portion of the piston, viewed in an extension, within the groove, i. that the imaginary extension of the piston outer surface in the region below the foremost sealing lip, which then protrudes in the feed direction over the foremost sealing lip, the trough t. This results in a favorable support of the sealing lip, in particular in the direction opposite to the feed direction.

Further features of the invention are described below, also in the figure description, often in their preferred assignment to the claim concepts already explained above, but they can also be assigned to only one or more individual features, as described here, in particular the already negotiated claims, or be independent or in another overall concept of importance. It is also possible to combine the measures of the claims already dealt with. Thus, it is further preferred that the piston in the case of a sweep of a sealing lip forward in the feed direction over a foremost portion of a front, swept forward forward sealing lip front portion has. The protruding in the feed direction of the piston over the front in the feed direction sealing lip front portion of the piston leads to a favorable pressurization in the region of the piston surface. Also, this is a practically complete emptying of the syringe barrel reached. With a suitable design, it is possible to achieve a very extensive emptying of the syringe barrel, up to an almost complete emptying. The suitable design consists in particular in an adaptation to an inner contour of the syringe barrel in the region of the transition to the needle hub or to the outlet opening. In this regard, a conical design of the front portion is preferred with a central, in particular the piston longitudinal axis receiving, projecting in the feed direction and a leading outgoing circumferential and in cross section at an acute angle to a transverse plane to the longitudinal axis engaging surface. In a favorable manner, the circumferential sealing lip, in particular the front sealing lip, is also supported in its sealing action as a result of an advancing movement of the piston for dispensing a liquid. The tip itself may be rounded in a contour.

In a possible embodiment, the piston in the case of a backward sweep may have a given over a subsequent in the direction of the arrow cylindrical portion radial projection corresponding to one sixth or more to one third of the diameter of the cylindrical portion, wherein a Thickness of the supernatant in the direction of a longitudinal axis of the piston on one half of the radial projection of a six-axis tel or less up to a tenth or one twentieth of the diameter.

The pointing in the feed direction surface of the foremost, swept sealing lip can steplessly and evenly pass into the direction of feed in the end face of the piston, these mitbildend corresponding, more preferably this forward facing in the feed direction end face of the piston is formed in a circular cone shape.

It can also be provided that in succession a plurality of sealing lips are formed in an axial direction of the piston, which can each be provided with the mentioned sweep. Thus, for example, two or three, moreover possibly more than three, so for example four or five circumferential sealing lips may be provided. In particular, the forwardmost in the feed direction sealing lip preferably has a swept orientation. This can also be provided for all other sealing lips or only for a part of the other sealing lips.

[0028] In one possible embodiment, all the circumferential sealing lips provided may have the same diameter, in particular those diameters which are chosen to be larger in order to obtain sufficient tightness than the internal diameter of the syringe cylinder receiving the piston.

In an alternative embodiment, a sealing lip is provided with a reduced diameter relative to the foremost sealing lip. Such a sealing lip takes on less sealing tasks, but has a supporting effect of the piston on the cylinder inner wall. So can opposite the feed direction below the foremost sealing lip all other sealing lips have such a reduced diameter.

For example. the reduced diameter may correspond to the inner diameter of the syringe barrel. The front portion of the piston may have a curved contour in cross-section, wherein the contour line merges with a concave curvature in the foremost sealing lip. The transition of the contour line may be in cross-section or formed within a largest piston diameter.

More preferably, the piston can be made in one piece and the same material, without a given in the direction of feed direction mold parting line. Since the piston usually also has a coincident with the feed direction central axis, the characterization can be given that the piston is made without axial mold parting line. As a result, it can be achieved that no mold parting line is provided, which runs crosswise to a sealing lip. As at a mold parting line sometimes

Defects revealed, thereby possibly caused by leaks can be excluded. On a mold parting line running at a cross-section to a sealing lip, unevenness or small protrusions in the material can also occur, which could lead to abrasion and thus to the separation of material particles. Such is also excluded accordingly. Even with an ideal mold parting line, leaks can not be ruled out because the relatively hard mold parting line area can not deform or insufficiently deform to secure the seal.

The primary sealing region, which is given in particular by a free end region of a frontmost sealing lip, is preferably a separating line. free. In particular, it is preferred that a mold parting line extending transversely to the feed direction or a transverse to the central axis of the piston extends outside a region of a sealing lip with a radially largest extent. More preferably, the mold parting line is perpendicular to the feed direction or the central axis.

The mold parting line also preferably runs continuously in the same plane. The relevant plane is perpendicular or nearly perpendicular to the feed direction or the central axis. The mold parting line can further preferably on a rear or underside of a sealing lip, so facing away from a front free end of the piston run. As a result, although a certain undercut on the sealing lip can result in a production form, but the demoldability does not conflict with a production in the plastic injection molding process. On the one hand, the undercut can be kept sufficiently low, so that the demoulding, possibly still increased over a subsequent state, given elastic deformability is sufficient to demold from the undercut, on the other hand, also form-technical precautions can be taken, such as obliquely to the central axis movable moldings are provided.

The mold parting line may be continuous, but in this case preferably offset relative to a sealing region of the sealing lip which is relevant in use. Nevertheless, the mold parting line may still be formed in the sealing lip itself, in the feed direction in front of or behind the relevant sealing region of the sealing lip.

The piston may, as also preferred, be integrally formed with the material or the material together with the one or more sealing lips. The piston Sealing surface including the sealing lips is formed by the piston plastic material alone.

The piston may be made by plastic injection molding. A sweep can also be achieved after removal from the mold, for example in cooperation with the piston having a hollow shape which has a correspondingly smaller inner diameter than corresponds to the outermost diameter of a sealing region.

The piston may be made entirely of a fluorine-based plastic material. Also possible is a combined piston design, for example a combination of two different fluoropolymer materials. In addition, a piston core encapsulated with fluorine-based plastic material can also be provided, for example a metal core or a core consisting of another (non-fluorine-based) thermoplastic material or even of an elastomeric material (for example rubber). The medical syringe with a cylindrical body in which a piston is inserted is provided with a piston having one or more of the features described above and below with respect to the piston. The body of the medical syringe is preferably formed without an inner coating for increasing the lubricity, and more preferably, in particular, without a coating comprising silicone oil or silicone oil constituents.

With regard to the disclosure, the ranges and value ranges or multiple ranges given above and below also include all intermediate values, in particular in 1/10 increments of the respective dimension, if appropriate also without dimensions. For example, includes the disclosure of one third, or 0.33 or more, also the disclosure of 0.43 or more, the specification of one sixth or 0.17 or less also the disclosure of 0.07 or less, the indication 1,1- to 1, 5-fold also the disclosure of 1.2- to 1.5-tray, 1.1- to 1.4-tray, 1.2- to 1.4-tray, etc. This disclosure can on the one hand to delimit an area mentioned limit from below and / or above, but alternatively or in addition to the disclosure of one or more singular values from a respective specified range serve.

Brief description of the drawings

The invention will now be described with reference to the accompanying drawing, which, however, shows only exemplary embodiments. A part that is explained only with reference to one of the embodiments and is not replaced in another embodiment due to the special feature there is not replaced by another part, is thus described for this further embodiment as a possible existing part anyway. On the drawing shows:

Figure 1 is a partial sectional view of a medical syringe with a piston in a first embodiment.

2 shows the piston in a partial sectional view.

FIG. 2a shows an embodiment of the piston according to FIG. 2 modified with regard to the front section; FIG.

FIG. 3 shows the enlargement of region III in FIG. 2; FIG.

FIG. 4 shows the enlargement of the region IV in FIG. 2; FIG. 5 shows the piston according to FIG. 2 in a perspective illustration;

Fig. 6 is a further perspective view of the piston according to

Figure 2;

Fig. 7 is a representation corresponding to Figure 2, but a second

Concerning an embodiment of a piston;

FIG. 8 shows the enlargement of the region VIII in FIG. 7; FIG.

FIG. 9 shows the enlargement of the region IX in FIG. 7; FIG.

10 shows the piston of the second embodiment in perspective

Presentation;

Fig. 11 is another perspective view of the piston of the second embodiment;

Fig. 12 is a sectional view according to Figure 7, concerning a further

Embodiment of the piston; and

Fig. 13 is a detail view of a piston showing a

Mold parting line in the area of a sealing lip.

Description of the embodiments

Shown and described is first with reference to Figure 1, a syringe 1 for medical purposes. The syringe 1 is composed essentially of an elongated cylinder open on both sides, in particular cylindrical body 2, and a piston 3 displaceable in the cylindrical body 2 in the feed direction r or counter to the feed direction r. The cylindrical body 2 consists for example of glass, alternatively cyclo-olefin copolymer (COC) or cyclo-olefin polymer (COP), and has a distal end 4 and a proximal end 5. In the region of the distal end 4 of the cylindrical body 2 goes over a tip-shaped needle attachment 6.

In the region of the proximal end 5, a radial expansion in the form of a flange 7 is formed on the cylindrical body 2. This serves in the course of using the syringe 1 as a counter-holder to the lower handle preferably by the index and middle finger of the syringe 1 serving hand.

The piston 3 is connected to a piston rod 8. This passes through a provided in the proximal end 5 insertion opening 9 of the cylindrical body 2 and formed in the region of the free, the piston 3 end facing away from the longitudinal extent of the piston rod 8 aligned, plate-like thumb rest 10th

The piston rod 8 can, as shown, be formed in the form of cross-like arranged webs 11. The piston 3 is described below with reference to various embodiments.

The piston 3 of all embodiments is manufactured in one piece in the plastic injection molding process, this further from a fluorine-based Plastic material, preferably according to a fluorine-containing (co) polymer.

The piston 3 has a longitudinal axis x, which coincides in the use state according to Figure 1 with the longitudinal axis of the cylindrical body 2. In the longitudinal extension direction accessible from one end is coaxially to the longitudinal axis x a receiving opening 12 formed with an internal thread 13, for screw fixing the facing distal end of the piston rod eighth

The piston 3 is in use position facing the distal end 4 of the cylindrical body 2 facing with a front portion 14 is provided. According to the exemplary embodiments in FIGS. 1 to 11, the front section 14 may be designed conically in cross-section, preferably with a curvature transition assigned to the middle region, or further, for example, according to the illustrations in FIG. 2 or also FIG. 12 in a cross section in which the longitudinal axis x forms a line, having a curved contour, so that viewed from the piston 3 in the direction of the distal end 4, a convex protrusion of the piston 3 results. As further illustrated by way of example in FIG. 2 a, the front section may also have, preferably starting from a central region of the piston and enclosing it, a flat region which extends at least partially approximately at right angles back on the longitudinal axis of the piston.

This design of the piston according to Figure 2 or Figure 12 may also be given for all other pistons shown here. Through the given front portion 14 a complete squeezing of liquid from the interior of the cylindrical body 2 over the coaxial with the longitudinal axis x in the region of the distal end 4 arranged needle lug 6 is made possible. With reference to the embodiment according to the representations in FIGS. 2 to 6, the conical front section 14 passes over into a circular-cylindrical section 15 with a diameter d.

This section 15 merges into a rotationally symmetrical, cylindrical section 16 which, together with the front section 14, essentially determines the piston length considered in the extension direction of the longitudinal axis x. The cylindrical portion 16 is provided with the receiving opening 12 and the internal thread 13.

The cylindrical section 16 adjoining the section 15 has a diameter d 'which can be chosen to be larger than the diameter d in the region of the front section-side cylindrical section 15. In a preferred embodiment, the diameter d' can be approximately one , 1 to 1.5 times, further, for example, about 1.2 times the diameter d correspond.

In the exemplary embodiment illustrated in FIGS. 2 to 6, the diameter d 'remains the same over the length of the section 16, with the exception of the sealing lip areas described below.

In contrast, in the exemplary embodiment according to FIG. 12, a step-like radial widening of the cylindrical section 16 is provided in the region of a central sealing lip with respect to the longitudinal extent. It turns out that way a further diameter dimension d "in the end region of the section 16 facing away from the front section 14, which diameter dimension d" is approximately 1.1 to 1.5 times, further approximately 1.2 times that at the front section 14 or cylindrical section 15 subsequent diameter measure d or d 'can correspond.

Each diameter d, d 'and optionally d "is dimensioned smaller than an inner diameter of the cylindrical body 2. Accordingly, the piston 3 with its portion 16, as well as the possibly formed cylindrical portion 15 preferably does not come with an inner surface of the cylindrical Body 2 in touch.

For sealing the piston-body combination, in particular in the course of a displacement of the piston 3 within the body 2 in the feed direction r, at least one sealing lip 17 is provided. As also shown and preferred, a plurality of mutually spaced sealing lips can be provided over the length of the cylindrical section 16. For example, three sealing lips 17, 18 and 19 are provided, viewed over the axial length of the section 16, wherein the sealing lip 17 is assigned to the front area in the feed direction r, corresponding to the front section 14, and the sealing lip 19 to the end area facing away from the front section 14 of the section 16. The sealing lip 18 extends with respect to the axial direction approximately centrally and at least approximately uniformly spaced in the axial direction between the sealing lips 17 and 19th

One, several or even all sealing lips may be in accordance with the embodiments shown in Figures 1 to 11 in a cross section forward, ie in the feed direction r, be swept. This sweep is due to an orientation of the respective points which is acute-angled relative to the longitudinal axis x. Sealing lip, wherein the sealing lip 17, 18 or 19 in its direction extending centrally through line a, which is an angle bisecting the feed direction r facing sealing lip surface and the opposite direction of feed r facing sealing lip surface, with the longitudinal axis x an acute angle α of 30 to 60 °, more preferably 40 to 50 ° includes (see Figure 2).

The front portion 14 of the piston 3 protrudes in the feed direction r beyond the foremost sealing lip 17, with a dimension m which is 0.1 to 0.7 times, preferably 0.2 to 0.7 times, more preferably 0.5 times a smallest piston diameter. The smallest piston diameter is given by the diameter d 'approximately with reference to FIGURE 2 or 2a, as is the diameter d "with respect to FIGURE 12. The protrusion is oriented in the embodiment of FIGURES 2 and 2a In an embodiment according to FIG. 12, the protrusion is oriented at the intersection between the dimension auxiliary line relating to the dimension d 'and the front contour edge of the piston.

Furthermore, a swept-aligned sealing lip, in particular the foremost sealing lip 17, but possibly also, as is also preferred, the average sealing lip 18 considered in the longitudinal extent of the piston 3, as well as according to the first shown in Figures 2 to 6 Embodiment, the rear sealing lip 19, with respect to the feed direction r both above and below the same in each case over into a circular cylindrical portion of the piston 3, which may be formed by the portion 15 or the portion 16. Thus, the front sealing lip 17 is in the feed direction r over considered in the diameter-reduced cylindrical portion 15 and the lower side in the corresponding larger diameter portion 16 via.

The middle sealing lip 18 can merge on the upper and lower sides into a section 16 of equal diameter design over the axial length (see FIG. 7, the middle sealing lip 18 formed in the step region of the section 16 merges with the section 16 with the diameter d 'and the underside with the enlarged section of the section 16 with the section 16 Diameter d ".

The rear, possibly third, sealing lip 19 may be formed as a conventional, strictly radially aligned, sealing lip as shown in Figures 7 and 9.

The swept position of the sealing lips results in a circumferential groove 20 between the sealing lip surface pointing in the feed direction r and the associated lateral surface of the section 15 or section 16. A sealing lip protrudes into a cross section, for example according to FIGS. 2 or 7 considered over the largest piston diameter, here piston diameter d 'in Figure 2 or piston diameter d "in Figure 7. Preferably, all grooves 20 protrude all swept to the front sealing lips beyond the largest piston diameter.

In a further preferred embodiment, a piston outer surface, which is extended in the feed direction r, adjoins the section 16 of the piston 3 adjoining the forwardmost sealing lip 17 in the feed direction r, viewed in an extension, which here corresponds to the dimension line d ', the rim Thus, it runs within the channel 20. The imaginary extension of the piston outer surface accordingly passes through the channel 20 in the feed direction r up to a projecting beyond the foremost sealing lip 17th

An immediate transition of the front section 14 into the front sealing lip 17 can also be formed, corresponding to the omission of a cylindrical section 15, cf. approximately Figure 12. The considered in cross-section curvature of the front portion is in this design with a concave curvature directly into the sealing lip 17 on. The transition can be viewed in cross-section at an intersection with a line corresponding to the largest diameter d '.

The end face facing away from the front portion 14, in a transverse plane to the longitudinal axis x aligned end face may be formed smooth surface. Also can be formed integrally and uniform material from the piston material out hemispherical elevations 21 on this face. It is possible for a plurality of such elevations, for example five, six to ten, to be arranged on a circular line running concentrically with respect to the longitudinal axis x, with a spacing which is preferably uniform in the circumferential direction (see FIGS. 7 to 11).

The piston 3 is preferably produced in the plastic injection molding method, this further preferably in one-piece, preferably of material-uniform design. The complete surface of the piston 3 is given solely by the piston material.

The diameter dimension e of the sealing lip 17, which is decisive for the sealing of the piston 3 relative to the inner wall surface of the cylindrical body 2, is somewhat larger in order to ensure the sealing engagement. in this case, this sealing lip diameter e may correspond to approximately 1.1 to 1.5 times, further approximately 1.2 times the diameter of the piston section d '.

The further sealing lips 18 and 19 may have the same diameter e as the sealing lip 17. These then likewise come into sealing contact with the inner wall surface of the body 2.

Alternatively, the further sealing lips 18 and 19 according to the embodiment shown in Figures 7 to 11 with respect to the sealing lip 17 may be reduced in diameter. Thus, they can have a diameter e 'substantially equal to the inner diameter of the cylindrical body 2. The sealing lips 18 and 19 with such a diameter e 'take on less sealing tasks, but rather a friction-reduced support of the piston 3 on the Wandungsinnenfläche the body 2. Thus, with sufficient sealing between the piston 3 and the body 2 via the sealing lip 17 through the further sealing lips 18 and 19 given a guide of the piston 3 over its length. This provides in particular a high layer stability of the piston in the cylinder of the body. 2

The front in the feed direction r sealing lip 17 may be in accordance with the further embodiment shown in Figure 12 in a cross section to the rear, ie against the feed direction r, be swept. Here, too, this arrowing results from an alignment of the sealing lip 17 that is acute-angled relative to the longitudinal axis x. A line a passing centrally through the sealing lip 17 in its direction of extension, which is an angle bisector of the sealing lip surface pointing in the feed direction r and the direction opposite to the feed direction r facing sealing lip surface is, with the longitudinal axis x an acute angle α 'from 45 to 75 °, more preferably includes about 50 to 60 °. The front section 14 of the piston 3 projecting beyond the foremost sealing lip 17 in the advancing direction r is designed in this embodiment as a circular cone, the sealing lip surface of the foremost sealing lip 17 pointing in the advancing direction r in the exemplary embodiment shown at the same time and steplessly in FIG the end face of the front portion 14 enters.

The front sealing lip 17, as viewed in the direction of the feed direction r, transitions into a cylindrical section 16 reduced in diameter with a diameter d '.

The middle and lower sealing lips 18 and 19 are bead-shaped in cross-section in the embodiment, with the middle sealing lip 18 on the upper side, i. The lower sealing lip 19 is bounded on both sides by the larger diameter portion. [0080] As already described with reference to the embodiment in FIG , as preferred, the diameter e of the foremost sealing lip 17 may be greater than the diameter e 'in the region of the further sealing lips 18 and 19.

The sealing lip 17 has a radial projection f, which corresponds to two tenths or more of the diameter d 'of the cylindrical section 16, relative to the cylindrical section 16 immediately opposite the feed direction r. The radial projection f may also correspond to one-sixth or more of the diameter d 'of the cylindrical section 16. Moreover, the protrusion amount f may correspond to one third of the diameter d 'of the cylindrical portion 16 or more. The supernatant measure can also be given in a range between two tenths and four tenths of the diameter d '.

The thickness g of the sealing lip 17 considered in the direction of the longitudinal axis x may be in a central region viewed in the radial direction, in particular on half of the projection f, approximately four tenths or less, up to two tenths or one sixth or less of the diameter d ', possibly even up to, for example, one twentieth of the diameter d' correspond.

With reference to FIG. 13, a fragmentary representation of a piston is reproduced, in cross-section, in which a mold parting line 22, which here shows a punctiform image, is reproduced. Obviously, this mold parting line 22 is within, i. set back radially inward, given a largest diameter e of the piston 3 in the region of a sealing lip 19. The sealing lip 19 is selected here only as an example for illustration. It may also alternatively or additionally be a sealing lip 17 and / or 18 act. The shape may also have a number of separations over the length of the piston (horizontal, i.e. transverse to the later direction of advance). The illustrated mold parting line can thus lead to a certain, albeit slight, undercut with respect to removal from a mold in the region of a sealing lip 17, 18, 19.

The above explanations serve to explain the inventions as a whole, which further develop the state of the art independently, at least by the following feature combinations, namely: A piston, which is characterized in that the piston 3 in the plastic injection molding method is made of a fluorine-based plastic material.

A piston, which is characterized in that the piston 3 in the case of a sweep forward in the feed direction r has a projecting beyond a foremost portion of a frontmost sealing lip 17 front portion 14.

A piston, which is characterized in that the piston 3 with respect to a sealing lip 17, 18, 19 in the case of a backward sweep has a given over a subsequent in the direction of the arrow cylindrical portion 16 radial projection f, the one Sixth or more of the diameter d 'of the cylindrical portion 16 corresponds.

A piston characterized in that the projection f corresponds to up to two tenths or up to one third of the diameter d 'of the cylindrical portion 16, or more.

A piston which is characterized in that a thickness g of the supernatant f in the direction of a longitudinal axis x of the piston 3 on one half of the radial projection f corresponds to four tenths or less of the diameter d '. A piston which is characterized in that the thickness g corresponds to one sixth or less, approximately to one tenth or less of the diameter d '. A piston, which is characterized in that the piston 3 is made of a fluorine-based material in the plastic injection molding method that the piston 3 counter to the feed direction r below a frontmost sealing lip 17 a largest piston diameter d ', d "forms and that a channel 20 formed by the swept-forward sealing lip 17 with respect to a central region of the piston 3 extends in a cross-section radially beyond the largest piston diameter d ', d ".

A piston, which is characterized in that in an axial direction of the piston 3 in succession a plurality of sealing lips 17, 18, 19, which have a forward sweep on a given for the application of liquid from the syringe 1 in use feed direction r, are formed.

[0093] A piston, which is characterized in that in an axial direction of the piston 3, a plurality of sealing lips 17, 18, 19 are formed, which has a backward sweep to a given for the application of liquid from the syringe 1 in use Feed direction r have.

A piston, characterized in that the piston tip is formed by a contour curved in cross-section, wherein the contour line merges with a concave curvature in the frontmost sealing lip 17, wherein the transition in cross-section on or within a largest piston diameter d ', d "is formed.

A piston, which is characterized in that a mold parting line 22 in the region of a sealing lip 17, 18, 19 is set back radially inwardly with respect to a maximum diameter e of the piston. [0096] A piston characterized in that the piston 3 is made in one piece.

[0097] A medical syringe 1 having a cylindrical body 2 into which a piston 3 is inserted, the piston 3 having one or more of the features described above with respect to the piston as such.

All of the disclosed features are essential to the invention (individually, but also in combination with one another). The disclosure of the associated / attached priority documents (copy of the prior application) is hereby also incorporated in full in the disclosure of the application, also for the purpose of including features of these documents in claims of the present application. The subclaims characterize with their features independent inventive developments of the prior art, in particular to make on the basis of these claims divisional applications. The invention specified in each claim may additionally have one or more of the features described in the preceding description, in particular with reference numerals and / or given in the reference numerals. The invention also relates to design forms in which individual features mentioned in the above description are not realized, in particular insofar as they are recognizably dispensable for the respective intended use or can be replaced by other technically equivalent means. List of reference numbers

1 syringe 22 mold parting line

2 bodies

3 pistons

4 distal end a line

5 proximal end d diameter

6 Needle extension d 'diameter

7 flange d "diameter

8 piston rod e diameter

9 insertion opening e diameter

10 thumb rest supernatant

11 bridge S thickness

12 receiving opening m dimension

13 internal thread r Feed direction

14 front section u arrow

15 Section X longitudinal axis

16 cylindrical section

17 sealing lip

18 sealing lip α angle

19 sealing lip α 'angle

20 gutter

21 Survey

Claims

claims

1. In the plastic injection molding produced piston (3) for a

medical syringe (1), wherein the piston (3) one or more

Sealing lips (17, 18, 19), wherein further a sealing lip (17, 18, 19) in cross section to the front or to the rear relative to a

Application of liquid from the syringe (1) in use given feed direction (r) is swept, characterized in that the piston (3) in the plastic injection molding of a fluorine-based

Plastic material is made.

2. Piston according to claim 1, characterized in that the piston (3) in the case of a sweep forward in the feed direction (r) over a foremost portion of a frontmost sealing lip (17) protruding front portion (14).

3. Piston according to claim 1, characterized in that the piston (3) with respect to a sealing lip (17, 18, 19) in the case of a sweep to the rear over a subsequent in the direction of the arrow cylindrical portion (16) given radial projection (f), which corresponds to a sixth or more of the diameter (d ') of the cylindrical portion (16).

4. Piston according to claim 3, characterized in that the supernatant (f) up to two tenths or up to one third of the diameter (d ') of the cylindrical portion (16), or more corresponds.

5. Piston according to one of claims 3 or 4, characterized in that a thickness (g) of the supernatant (f) in the direction of a longitudinal axis (x) of the Piston (3) on one half of the radial projection (f) four tenths or less of the diameter (d ') corresponds.

Piston according to claim 5, characterized in that the thickness (g) up to a sixth or less, approximately to one tenth or less of the diameter (d ') corresponds.

A plastic syringe produced piston (3) for a medical syringe (1), wherein the piston (3) one or more sealing lips (17, 18, 19), wherein further a sealing lip (17) in cross-section a forward relative to a feed direction (r) given for the application of liquid from the syringe (1) during use is swept, characterized in that the piston (3) is produced in the plastic injection method from a fluorine-based material, that the piston (3) counter to the feed direction (R) below a foremost sealing lip (17) a largest piston diameter (d ', d ") is formed and that a by the swept up to the front sealing lip (17) opposite a central region of the piston (3) formed groove (20) in a cross section considered radially beyond the largest piston diameter (d ', d "protrudes).

Piston according to one of claims 1, 2 or 7, characterized in that in an axial direction of the piston (3) in succession a plurality of sealing lips (17, 18, 19) which a forward sweep on a for applying liquid from the syringe (1 ) in use given feed direction (r), are formed.

9. Piston according to one of claims 1 or 3 to 6, characterized in that in an axial direction of the piston (3) in succession a plurality of sealing lips (17, 18, 19) are formed, which is a swept backwards pulled to a given for the application of liquid from the syringe (1) in use feed direction (r).

10. Piston according to one of the preceding claims, characterized in that the piston tip is formed by a curved contour in cross-section, wherein the contour line merges with a concave curvature in the foremost sealing lip (17), wherein the transition in cross-section on or within a largest piston diameter (d ', d ") is formed.

11. Piston according to one of the preceding claims, characterized in that a mold parting line (22) in the region of a sealing lip (17, 18,

19) set back radially inwardly with respect to a maximum diameter (e) of the piston.

12. Piston according to one or more of the preceding claims,

characterized in that the piston (3) is made in one piece.

13. A medical syringe (1) with a cylindrical body (2) into which a piston (3) is inserted, wherein the piston (3) has one or more of the features of claims 1 to 12.