WO2009118361A1

WO2009118361A1 - Apparatus for plasma treatment of hollow bodies

Info

Publication number: WO2009118361A1
Application number: PCT/EP2009/053547
Authority: WO
Inventors: Thomas Virot; David Benjamin Montgomery; Yves Enfoux; Laurence Boulange
Original assignee: Becton Dickinson France
Priority date: 2008-03-25
Filing date: 2009-03-25
Publication date: 2009-10-01
Also published as: FR2929295A1

Abstract

The present invention concerns an apparatus for plasma treatment of the interior walls of at least one hollow body comprising: - at least one support (4) adapted to the exterior dimensions of the hollow body (12), - at least two metallic electrodes (8) having, on their surfaces, lumens able to receive the said hollow bodies, characterized in that said apparatus comprises a hood (1 ) comprising means (10) for delivering a gas into the interior volumes of said hollow bodies and a system for plasma treatment of the interior walls of at least one hollow body, said system comprising said apparatus. It also concerns a method for chemical vapor deposition of a coating on the interior walls of at least one hollow body implementing said system. It also concerns a hollow body having an L/D ratio greater than or equal to 3, preferably greater than or equal to 5, L being the length and D being the diameter of said hollow body, said hollow body having an interior coating of a thickness between 300 and 500 nm having variations below 20%.

Description

APPARATUS FOR PLASMA TREATMENT OF HOLLOW BODIES

[0001] The invention concerns an apparatus and a method for plasma treatment of hollow bodies, for example syringes, having small internal diameters. It more particularly relates to the coating of the internal walls using the chemical vapor deposition technique for said hollow bodies.

[0002] Although chemical vapor deposition techniques have been widely used for coating tubes and/or hollow bodies, the coatings obtained are often not regular enough and have flaws which are not compatible with the required specifications, for example in the field of syringe production for use in the pharmaceutical industry, when said hollow bodies have a significant length and a small cross-section.

[0003] Methods of this type for coating the inside of hollow bodies have been described for example in patent US 5702270, which teaches the use of said hollow bodies as reaction chambers subjected to a vacuum before being filled with the gas that will be used to carry out the deposition. The use of the hollow body as a chamber makes it possible to avoid using an external chamber which must be cleaned, maintained and integrated into the industrial process. The electrodes to produce the energy can be moved to improve the homogeneity of the deposition and can also be adapted to different hollow bodies to be coated.

The adaptation of the device to the different objects to be treated depending on the productions will also be easier; indeed, only the electrodes and the gas will be modified depending on the objects to be coated. Based on the same method, patent EP 0787823 disclosed the coating of plastic containers, like blood collection tubes.

[0004] In application US-2002/0155218, a method to improve the uniformity of the coating comprising a closing phase for one of the open ends of the hollow body to be coated by a gas-tight device. This closing makes it possible to obtain a more homogenous and consistent deposition over the entire interior surface of the treated hollow body.

[0005] In application WO 9815669, an apparatus, comprising a chamber made of an electrically insulating material, a main electrode adjacent of an exterior surface of said chamber and a counter electrode inside the container is disclosed; this system improves the uniformity of the deposited film.

[0006] Patent US 5972436 teaches a method to improve the uniformity of the coating, using a process including a step for prior heating of the interior of said hollow body by initiating a plasma by filling this with oxygen, then releasing the plasma when the desired temperature is reached, gas supply which will be used for the coating with initiation of a new plasma.

[0007] Patent EP 1493839 describes a CVD film forming apparatus for plastic containers, which comprise internal and external electrodes and a cover, constituting the film forming chamber; this device allows to form CVD films on the inner and/or the outer surface of the containers.

[0008] The same device is disclosed in the patent EP 1652961 to form a sealable vacuum chamber; a dry gas is first filling in the inside of the container and then is replaced with a source gas which is then converted to plasma. This method makes it possible to improve the container drying efficiency.

[0009] In order to reduce the risk of deposition of dust on the internal electrode and thus to obtain a complete plasma generation, patent EP 1508360 teaches to replace it by a mouth side electrode which faces the external electrode.

[00010] Coating of only one part of the hollow body to be treated was described, for example, in US-5318806, which teaches a method making it possible to obtain a gradient of the chemical deposition done on the object depending on the position of said object in relation to the very high-density plasma which is generated in a volume surrounding the electrode. The closer the surface of the object is to the electrode, the more the plasma undergone is intense and allows more significant deposition, the more the surface of the object is distanced from the electrode, the weaker the deposition.

[00011] A method enabling simultaneous coating of several parts with uniformity and reproducibility of the layers deposited, but also good yield, was described in patent application US-2005/0005853. The method makes it possible, from a single microwave source, thanks to a wave guide whereof different structures are described, to generate a plasma simultaneously in all of the chambers, which can be formed by the parts that must be coated. [00012] Patent WO200722976 teaches an apparatus with two parallel electrodes for the plasma treatment of internal and external surfaces of hollow bodies, like syringes; but this structure is not adapted for mass production. [00013] Patent US-61177148 teaches a method leading to a simultaneous uniform coating of several pieces using a pulsed method with chronologically- controlled adjacent antennae which make it possible to supply the electrodes of two adjacent objects needing to be coated, at different times to avoid interferences between the plasmas thus created. [00014] Patent EP1516941 describes a rotary CVD film forming apparatus for plastic containers, which comprise internal electrodes inside the containers and external electrodes capable of housing a plurality of containers. By using this structure, it is possible to achieve compactness or a multi-fold increase of the productivity.

[00015] Beyond the problems described above of homogeneity and simultaneity of the coating of several pieces, it appears that the interior coating of pieces having small diameters raises particular problems which were described in patent US-4948628, which describes a plasma-generating device making it possible to coat the interior walls of a tube having a small diameter, said apparatus comprising a diaphragm which separates two chambers into a first chamber equipped with a gas inlet and a second chamber connected to a vacuum source. A dielectric protects the electrodes from any plasma discharges outside the area between the two electrodes. The pressure difference between the two chambers makes it possible, while maintaining a pressure difference between the proximal end and the distal end of the tube, to obtain uniform deposition at the two ends and a flow of gas inside said tube.

[00016] Patent WO200708184 disclose a lubricious coating and a protein deterrent coating by plasma treatment on the inside wall of pharmaceutical pakages like syringes; this method allows to reduce the adsorption of proteins on the surface of the container but is not associated with a specific apparatus. [00017] Patent EP 0709105 disclosed syringes with internal lubricating layers deposited by a CVD process. But there is no specific apparatus combined with this process. [00018] The present invention makes it possible to resolve the above mentioned drawbacks and to perform coatings whereof variations in thickness are small inside the hollow body having a significant length and a small diameter, while also making it possible to perform the coating on all or part of said hollow bodies. The present invention also makes it possible to carry out said coatings simultaneously on series of hollow bodies, thereby allowing industrialization of the process.

[00019] The present invention consists of an apparatus for plasma treatment of the interior walls of at least one hollow body comprising: - at least one support adapted to the external dimensions of the hollow body, - - at least two metallic electrodes having, on their surfaces, lumens able to receive the said hollow bodies, characterized in that said apparatus comprises a hood comprising means for delivering a gas into the interior volumes of said hollow bodies.

[00020] In one embodiment, said hood forms, with the support, an intermediate chamber to distribute gas into the interior volumes of several hollow bodies. [00021] Chemical vapor deposition (CVD) is a method for depositing thin films from gaseous precursors. The principle consists of injecting, under a controlled atmosphere, gaseous precursors, then the substrate is heated and the chemical deposition reaction takes place on the surface after absorption of the gaseous reagents. Preferably, plasma assisted (or enhanced) chemical vapor deposition (PACVD or PECVD) is used in the present invention.

[00022] According to the invention, the apparatus is made up of assembled adjacent modules, each module comprising a support adapted to receive at least one hollow body.

[00023] The apparatus thus has a flexible capacity and can be adapted to perform a coating on a set of hollow bodies comprising a variable number of hollow bodies and thus enables adaptation of the size of batches according to production needs.

[00024] The apparatus also comprises screens which can be placed on one of its external surfaces, on both sides and/or at the lower part of the modules, to obtain uniform and intense plasma distribution inside the hollow bodies. [00025] The apparatus according to the invention is adapted to a cylindrical hollow body, having an L/D ratio greater than or equal to 3, preferably greater than or equal to 5, L being the length and D being the diameter of said hollow body. [00026] The support of the apparatus according to the invention is particularly adapted to syringe bodies.

[00027] The invention also concerns an apparatus according to the invention characterized in that it also comprises means for adjusting the distance between said electrodes. [00028] In one embodiment, said means are insulating spacers.

[00029] The presence of these means makes it possible to adapt the device to the length of the hollow bodies, or to cover only part of said hollow bodies by positioning the electrodes at the level where the interruption of the coating is desired. In the apparatus of the invention the means to adjust the distance and the holder are separated.

[00030] The electrodes are thus perpendicular to the central axis of the hollow body and own lumens able to receive the hollow bodies as the insulative spacers in order to complete the holder for the hollow bodies.

[00031] In one embodiment, the height of the coating is between the flange and the shoulder formed in front of the tip of the syringe, preferably on the length corresponding to the travel of the piston.

[00032] In one embodiment, the gas can escape via the end opposite the end enabling introduction of the gas into said hollow body, the end of the hollow body forming an escape means for the gas. [00033] When this end has an opening with a diameter smaller than that of the opening enabling the introduction of the gas, for example when said hollow bodies are syringes, on which the needles are mounted, the difference in diameter between the hollow body and the needle being able to create an overpressure in the hollow body, an escape means constituted by an orifice is arranged at the upper part of the apparatus. Said escape means is, for example, an orifice placed at the end also allowing introduction of the gas. In this embodiment, a gas escapement channel is arranged on the upper part of the hood. [00034] Said invention thus enables the coating of the interior walls of hollow bodies whereof one end is closed or whereof one end is partially obstructed, for example syringes on which the needles were previously fixed without risk of deposition of the coating in the needles, the electrodes being able to be positioned at a level higher than that of the needles.

[00035] In one embodiment, the plasma treatment is a chemical vapor deposition treatment.

[00036] In one embodiment the plasma treatment is an oxidizing plasma cleaning treatment. [00037] Oxidizing plasma designates the creation of a plasma after filling of the hollow body with a gaseous mixture essentially containing oxygen.

[00038] In one embodiment, one performs two successive treatments, an oxidizing plasma in the presence of oxygen then, after evacuation of the oxygen and refilling of the hollow body by suitable gaseous precursors, one performs a chemical vapor deposition coating treatment.

[00039] The present invention also concerns a system for plasma treatment of the interior walls of at least one hollow body, said system comprising:

- an apparatus according to the invention as defined above,

- a chamber adapted to contain said apparatus, - means for creating a plasma discharge between said electrodes,

- means for distributing a gas in the interior volume of said hollow body. [00040] In one embodiment, said chamber also comprises:

- means for creating and maintaining a predetermined pressure level in the apparatus. [00041] In one embodiment the predetermined pressure level is a vacuum, for example an average vacuum from 1 to 10^~3 mbar (10² to 10^~1 Pa) or a high- vacuum from 10^"3 to 10^"7 mbar (10^"1 to 10^"5 Pa).

[00042] In another embodiment, the predetermined pressure level is the atmospheric pressure, or approximately 101 ,325 Pa. [00043] The means for creating the plasma discharge between the two electrodes are radio-frequency means in another embodiment, or microwaves in still another embodiment. [00044] In one variation of the system, at least one of the electrodes is connected to the ground.

[00045] The invention also concerns a method for chemical vapor deposition coating of the interior walls of at least one hollow body comprising the steps of: a) positioning said hollow body in the support of an apparatus according to the invention as defined above, b) creating and maintaining a predetermined pressure level in said apparatus, c) introducing a gas into the internal volume of said hollow body, d) creating a plasma discharge between the two said electrodes.

[00046] In one embodiment, the predetermined pressure level is a vacuum. [00047] In another embodiment the predetermined pressure level is the atmospheric pressure.

[00048] The gas is chosen according to the treatment and/or coating targeted. [00049] When vapor deposition is done cold, the gas is chosen in the group made up of hexamethyldisiloxane (HMDSO), polyvinyhoodene chloride, fluorocarbon, silane derivatives, methane, thmethylstannyl (Sn(CH₃)₃, alone or mixed with air or oxygen.

When vapor deposition is done cold, the gas is chosen in the group made up of aluminum trioxyde, hexamethyldisiloxane (HMDSO), silane derivatives, methane, alone or mixed with air or oxygen. [00050] Using the method and the apparatus, the gas introduced and distributed via the hood will be shared out in the hollow bodies and only in the hollow bodies thanks to the pressure difference between the interior and the exterior of the hollow body.

[00051] The invention also concerns a glass syringe body coated according to a method according to the invention. In one embodiment, the glass is borosilicate.

[00052] The invention also concerns a plastic syringe body coated according to a method according to the invention. In one embodiment the plastic material is propylene or cyclopolyolefine, generic term designating, for example, a mixture of resins such as the "ZEONEX" resins provided by the company ZEON

CHEMICALS [00053] The invention also concerns a hollow body having an L/D ratio greater than or equal to 3, preferably greater than or equal to 5, L being the length and D being the diameter of said hollow body, said hollow body having an interior coating of a thickness between 300 and 500 nm having thickness variations less than or equal to 20%.

[00054] In one embodiment the invention concerns a method for cleaning by oxydative plasma of the interior walls of at least one hollow body comprising the steps of: a) positioning said hollow body in the support of an apparatus according to the invention as defined above, b) creating and maintaining a predetermined pressure level in said apparatus, c) introducing oxygen into the internal volume of said hollow body, d) creating a plasma discharge between the two said electrodes.

[00055] In one preferred embodiment, the apparatus comprises four spacers which are placed in the support to adapt the apparatus to glass syringe bodies with a capacity of 1 milliliter.

[00056] Two screens are also added to the two ends of the support, to obtain an intense and uniform plasma inside the syringe bodies.

[00057] The present invention will be well understood in light of the figures illustrating one particular embodiment of the invention. [00058] Figure 1 shows an exploded view of an apparatus according to the invention. [00059] Figures 2 and 3 show a general view of a module of the apparatus according to the invention in two assembly modes. [00060] Figure 4 shows a general view of an apparatus according to the invention.

[00061] Figure 5 shows a cross-section along axis XX of an apparatus according to the invention.

[00062] Figure 6 shows a syringe body having a coating on one part of the length of the syringe body. [00063] Figures 7, 8 and 9 show a diagrammatic view of the measuring capacities and contact angles.

[00064] The plasma treatment apparatus shown in an exploded view in figure 1 comprises a hood 1 having, on its lower surface, recesses 10 forming means to deliver gas into the interior volumes of the hollow bodies and forming, with the lower support, a chamber for distributing gas into the hollow body. The module shown comprises two electrodes 8, the surface of which has lumens able to receive the hollow bodies 12 shown in the exploded view and which are syringe bodies without needles. The apparatus also comprises a support 4 comprising lumens adapted to the abovementioned hollow bodies. Also shown are insulating spacers 5 to adapt the distance between the electrodes 8. Screens 6 which will be placed on each side of the modules, to obtain uniform plasma distribution inside the hollow bodies, are also shown. Assembly means, namely rods 13, nuts 14, butterfly nuts 15 and screws 16 are also shown to assemble the components described above. In the operation of the modules, namely the electrodes 8, the support 4 and the spacers 5 are assembled before insertion of the hollow bodies then the hood 1 and the screens 6. The apparatus is then placed in a chamber, the electrodes are connected to an energy source, and the orifices 11 are connected to a network which makes it possible to create a vacuum inside the hollow bodies, then to inject the gas inside said hollow bodies.

[00065] In figures 2 and 3 are shown a general view of a module of the apparatus according to the invention in two assembly modes. In figure 2, an assembly comprising a hood 1 of the electrodes 8, a support 4 of the spacers 5 and a screen 6 placed below the apparatus. The hood comprises a gas supply orifice 11. In the assembly of figure 3, the same apparatus is shown, but to allow application of the method to syringes comprising needles, the hood used comprises a degassing orifice 2. The modules thus shown can then be assembled to obtain an apparatus, which comprises several modules comprising a hood 1 comprising a gas supply orifice 11 , a support 4, spacers 5, electrodes 8 and screens 6, wherein hollow bodies according to the invention have been placed, as shown in figure 4.

[00066] Figure 5 shows a cross-section along axis XX of an apparatus as shown in figure 4. One sees, placed in said apparatus, hollow bodies 12 maintained in supports 4 which top spacers 5 which are placed between the electrodes 8. Screens 6 are placed between each module. The assembly done comprises five parts, A, B, C, D and E, parts A and B being designed to receive hollow bodies bearing a needle. To this end a degassing orifice 2 is arranged to enable the return of the injected gas. In modules C, D and E, the hollow bodies designed to be coated do not comprise needles, degassing can be done through the distal end of said hollow body, i.e. the area 22 of said hollow body. These modules therefore do not have degassing holes.

[00067] Figure 6 illustrates a syringe body having a coating 24 on part of the length of the syringe body. The coating is deposited over a length I of the syringe body, the total length of the body being shown by a length L and the diameter by the letter D. All of these variables are used in the continuation of the text, in particular in the examples and the tables, to characterize the bodies of the syringes subjected to a treatment according to the invention. [00068] The syringe body shown in figure 7 illustrates the measurement areas for contact angles, in particular in 20 the flange area, in 21 the middle of the syringe body, and in 22 the so-called needle area.

[00069] Figures 8 and 9 show contact angles with water at the surface of a substrate. [00070] Figure 8 shows a hydrophilic surface 25 not bearing a coating and a drop 23 which has a small contact angle with the surface.

[00071] Figure 9 shows a hydrophobic surface 24 comprising a coating whereon is positioned a drop 23 with a large contact angle with said surface 24. [00072] The invention will be better understood upon reading the following examples.

1 ) General appearance

[00073] All of the examples are conducted in glass syringes, of the BD Hypak™ brand, or CCP (Cristal Clear Polymer or cyclopolyolefine) polymer syringes. The gas mixture is made up of 20 SCCM air and 3.5 SCCM (Standard Cubic Centimeter Minute) of HMDSO (HexaMethylDiSiloxane). The plasma is generated by an 18 MHz radio scan frequency and a power of 400 V (peak to peak). The coating is done in a medium containing at least one row of ten syringes. The composition of the coatings is determined using the X-ray photoelectronic spectroscopy (XPS) method.

[00074] The XPS analysis is done using a spectrometer (SSX200, Surface Science) used at an Al Kn achromatic X-ray source (486.6 eV) operating at 10 kV with a power of 225 watts.

[00075] The spectors are obtained with a passing energy of 150 eV for all of the samples to determine which elements are present in the few nanometers of the top part of the coating surface. The value of the angle between the surface and the direction of electron detection is 35°. Working pressures are 4x10^"9 torrs and the analysis area is a circle with a diameter of 0.84 mm. The base area of the surface of the peak is removed before analysis of the specters. The shape of the lines used for the "curve fitting" analysis are 80% Gaussien and 20% Lorentzian for elements C 1 s and O 1s. The ratios between each element expressed in percentages were calculated using the surface of the peaks based on acquisitions and after subtracting the base line.

[00076] The contact angles with water of the different coatings were measured using the following method: after coating, the cylinders are cut using a diamond wire saw and the contact angles are measured on the length of the cylinder using an automatic goniometer equipped with software correcting the curve of the cylinder during measurement of the contact angle. A homogenous coating inside the cylinder of the syringe corresponds to contact angles with water measured at three different locations inside the coated cylinder (see figures 7, 8 and 9). The contact angles with water are expressed in degrees.

[00077] The L/D ratio for all of the samples is equal to 6.3 cm, L being equal to 5 cm and D being equal to 0.8 cm.

[00078] The length of the syringe body whereon a coating is done (coating length) I may vary (see figure 6).

Example 1 [00079] Influence of the £/D ratio for coating of glass syringes without needles.

[00080] A plasma coating is created on the syringes which are placed in the support. With an £/D ratio of 5.7, it is possible to create a plasma more deeply inside the syringes in comparison with a ratio of 4.4 (see results in table 1 below).

Table 1 [00081] Contact angle with water inside glass syringes

[00082] In conclusion, it is possible to obtain a coating using the apparatus and the method according to the invention because the contact angles are initially between 45° and 53° on uncoated glass and more than 90° after deposition of the coating.

[00083] Moreover, with a ratio of 5.7 the difference between the contact angles with water is smaller than with a ratio of 4.4, which shows a more homogenous coating inside the length of the syringe body.

Example 2

[00084] Coating of syringes with needles

[00085] Thanks to this invention, it is possible to create a plasma inside syringes even if these syringes have a needle fixed at one end. Thanks to the method according to the invention, stainless steel needles do not interact with the plasma (see results in table 2). The same quality plasma can be produced in syringes with or without a fixed needle.

Table 2

[00086] Examination of the plasma inside syringe bodies with fixed needles.

Example 3

[00087] Verification of the effectiveness of electrode positioning [00088] The optimal distance between two electrodes to obtain a homogenous and intense plasma over the entire length of the syringe (100°) corresponds to a ratio of 6.3. [00089] If the ratio £/D is too high (6.9), the plasma is then created outside the support, and polymerization residues are deposited at the end of the flange, inside the cylinder. Measuring the contact angle requiring a surface not contaminated by particles is, as a result, distorted. [00090] If the ratio is smaller than 6.3 (5.7), the plasma is then not formed over the entire length of the syringe, as illustrated by the variation of the contact angle values in table 3 below.

Table 3 [00091] Examination of the plasma inside glass syringes with adjustment for positioning of the electrode

Example 4

[00092] Optimization of the plasma for coating syringes with needles placed through addition of a screen.

[00093] The addition of a screen on each side of the support reduces the plasma discharge outside the device and creates a more intense and more uniform plasma inside the syringe cylinder (see table 4). Table 4

[00094] Examination of the plasma inside glass syringes with addition of a screen on each side of the support.

[00095] The coating inside the syringe body is more homogenous when one uses screens on the sides of the device because the standard deviation measured is smaller.

Example 5

[00096] Coating trial with several rows of glass syringes

[00097] Different supports with two, three or four rows of syringes to be coated were tested, and the results are shown in table 5 below. It is possible to coat glass syringes in an apparatus with several rows of syringes as shown by the contact angles obtained.

Table 5

5

Example 6

[00098] Use of inert or oxydizing gasses on glass or CCP (Cristal Clear Polymer) syringes

[00099] It is possible, in this apparatus with a ratio £/D = 6.3, to use different gases such as oxygen or air with HMDSO. The results obtained are shown in the table below on syringes with a ratio £/D = 6.3. By using air, the coating is made up of oxygen, silicone, carbon and nitrogen, it is a hydrophilic coating, whereas by using only oxygen, the coating is made up only of carbon, silicone and oxygen and becomes more hydrophobic. In this case, the oxygen/HMDSO and air/HMDSO ratios are 2 and 10, respectively.

Table 6

[000100] Comparison of the composition of the coating and wettability on glass syringes according to gas ratios

Example 7

[000101] Trial on CCP syringes [000102] A uniform and intense plasma is also generated in CCP (Cristal Clear

Polymer) cylinders (having the same dimensions as BD Hypak™ brand 1 milliliter syringes) using the same device as that described in example 4 with a decrease in power to 300 volts.

[000103] As previously obtained, it is possible to obtain a more hydrophilic coating by using a mixture of air and monomer (HMDSO) in comparison with a mixture of oxygen and monomer. In this case, the Oxygen/HMDSO and Air/HMDSO ratios are 1 and 10, respectively (see table 7). Table 7

[000104] Comparison of composition of a coating and wettability on CCP syringes according to the gas ratio

Claims

7CLAIMS

1. Apparatus for plasma treatment of the interior walls of at least one hollow body comprising: - at least one support (4) adapted to the exterior dimensions of the hollow body (12),

- at least two metallic electrodes (8) having, on their surfaces, lumens able to receive the said hollow bodies, characterized in that said apparatus comprises a hood (1 ) comprising means (10) for delivering a gas into the interior volumes of said hollow bodies.

2. Apparatus according to claim 1 , characterized in that said hood (1 ) forms, with the support (4), an intermediate chamber to distribute the gas into the interior volumes of several hollow bodies (12).

3. Apparatus according to any of preceding claims, characterized in that one end of the hollow body forms an escape means (2) for the gas.

4. Apparatus according to any of preceding claims, characterized in that an escape channel (2) for the gas is arranged on the upper part of the support.

5. Apparatus according to any of preceding claims, characterized in that it is made up of assembled adjacent modules, each module comprising a support (4) adapted to receive at least one hollow body.

6. Apparatus according to any of preceding claims, characterized in that it comprises at least one screen (6) placed on one of its exterior surfaces.

7. Apparatus according to any of preceding claims, characterized in that it is adapted to a cylindrical hollow body (12), having an L/D ratio greater than or equal to 3, preferably greater than or equal to 5, L being the length and D being the diameter of said hollow body.

8. Apparatus according to any of preceding claims, characterized in that said support is adapted to syringe bodies.

9. Apparatus according to any of preceding claims, characterized in that it also comprises means (5) to adjust the distance between said electrodes.

10. Apparatus according to claim 1 , characterized in that the means to adjust the distance between the electrodes are insulating spacers (5).

11. Method of chemical vapour deposition coating treatment which uses the apparatus of claims 1 to 10.

12. Method of oxidizing plasma cleaning treatment which uses the apparatus of claims 1 to 10.

13. System for plasma treatment of the interior walls of at least one hollow body, said system comprising:

- an apparatus according to any of preceding claims,

- a chamber adapted to contain said apparatus, - means to create a plasma discharge between said electrodes,

- means to distribute a gas in the interior volume of said hollow body.

14. System according to claim 13, characterized in that said chamber also comprises: - means to create and maintain a predetermined pressure level in the apparatus.

15. System according to any of claims 13 or 14, in which the predetermined pressure level is a vacuum.

16. System according to any of claims 13 or 14, in which the predetermined pressure level is the atmospheric pressure.

17. System according to any of claims 13 to 16, in which the means to create the plasma discharge between the two electrodes are radiofrequency means.

18. System according to any of claims 13 to 16, in which the means to create the discharge between the two electrodes are microwaves.

19. System according to any of claims 13 to 18 in which at least one of the electrodes is connected to the ground.

20. Method for coating the interior walls of at least one hollow body by chemical vapor deposition comprising the steps of: a) positioning said hollow body in the support of an apparatus according to any of claims 1 to 12, b) creating and maintaining a predetermined pressure level in said apparatus, c) introducing a gas into the internal volume of said hollow body, d) creating a plasma discharge between the two said electrodes.

21. Method according to claim 20, characterized in that the predetermined pressure level is the vacuum.

22. Method according to claim 20, characterized in that the predetermined pressure level is the atmospheric pressure.

23. Method according to any of claims 20 to 22, characterized in that said gas is chosen from the group made up of hexamethyldisiloxane (HMDSO), polyvinyhoodene chloride, fluorocarbon, silane derivatives, methane, thmethylstannyl (Sn(CH₃)₃ alone or mixed with air or oxygen.

24. Method according to any of claims 19 to 21 , characterized in that said gas is chosen in the group made up of aluminum trioxide, hexamethyldisiloxane

(HMDSO), silane derivatives, methane alone or mixed with air or oxygen.

25. Glass syringe body coated according to a method according to any of claims 20 to 24.

26. Syringe body according to claim 25, characterized in that the glass is borosilicate.

27. Plastic syringe body coated according to a method according to any of claims 20 to 24.

28. Syringe body according to the preceding claim, characterized in that the plastic material is propylene or a cycloolefin.

29. Hollow body having an L/D ratio greater than or equal to 3, preferably greater than or equal to 5, L being the length and D being the diameter of said hollow body, said hollow body having an interior coating, obtained to the method according to any of the claims 20 to 24, with a thickness between 300 and 500 nm having variations in thickness smaller than or equal to 20%.

30. Method for cleaning the interior walls of at least one hollow body by oxidative plasma, comprising the steps of: a) positioning said hollow body in the support of an apparatus according to one of claims 1 to 12, b) creating and maintaining a predetermined pressure level in said apparatus, c) introducing oxygen into the internal volume of said hollow body, d) creating a plasma discharge between the two said electrodes.