COATING METHOD
A method for coating a substrate surface such as a syringe part by PECVD is provided, the method comprising generating a plasma from a gaseous reactant comprising an organosilicon precursor and optionally an oxidizing gas by providing plasma-forming energy adjacent to the substrate, thus forming a coating on the substrate surface by plasma enhanced chemical vapor deposition (PECVD). The plasma-forming energy is applied in a first phase as a first pulse at a first energy level followed by further treatment in a second phase at a second energy level lower than the first energy level. The lubricity, hydrophobicity and/or barrier properties of the coating are set by setting the ratio of the O2 to the organosilicon precursor in the gaseous reactant, and/or by setting the electric power used for generating the plasma.
This specification claims the priority of U.S. Ser. Nos. 61/792,952 and 61/800,494, each filed on Mar. 15, 2013. These entire applications are incorporated by reference here to provide continuity of disclosure.
FIELD OF THE INVENTIONThe present invention relates to the technical field of fabrication of syringes and other medical devices having a lubricity coating applied by plasma enhanced chemical vapor deposition (PECVD), and more particularly to a method for applying a lubricity coating to an interior surface of a vessel using plasma enhanced chemical vapor deposition, to the use of a vessel processing system, to a computer-readable medium and to a program element.
BACKGROUND OF THE INVENTIONAn important consideration when regarding syringes is to ensure that the plunger can move at a constant speed and with a constant force when it is pressed into the barrel. For this purpose, a lubricity layer, either on one or on both of the barrel and the plunger, is desirable. A similar consideration applies to vessels which have to be closed by a stopper, and to the stopper itself, and more generally to any surface which should provide a certain lubricity.
In glass syringes, silicon oil is typically used as a lubricant to allow the plunger to slide in the barrel. Silicon oil has been implicated in the precipitation of protein solutions such as insulin and some other biologics. Additionally, the silicon oil coating is often non-uniform, resulting in syringe failures in the market.
SUMMARY OF THE INVENTIONThe present invention pertains to plastic vessels and medical devices, in particular vials and syringes, coated with thin PECVD coatings made from organosilicon precursors. These novel devices offer the superior barrier properties of glass and the dimensional tolerances and breakage resistance of plastics, yet reduce or eliminate the drawbacks of both materials. With designed modifications to the PECVD process, the surface chemistry of the coating can be predictably varied. In particular, a plasma coating (SiOxCyHz or its equivalent SiwOxCyHz, in which x is from about 0.5 to about 2.4 as measured by X-ray photoelectron spectroscopy (XPS), y is from about 0.6 to about 3 as measured by XPS, and z is from about 2 to about 9 as measured by at least one of Rutherford backscattering spectrometry (RBS) or hydrogen forward scattering (HFS)) is provided. This plasma coating improves lubricity (“lubricity coating”), thus eliminating the need for traditional silicon oil lubricants e.g. in syringes. Further embodiments of the invention are methods to influence the hydrophobicity/hydrophilicity of said coatings and the resulting coated devices.
An aspect of the invention is a method for preparing a lubricity coating on a plastic substrate, the method comprising: (a) providing a gas comprising an organosilicon precursor, and optionally an oxidant gas, and optionally a noble gas, in the vicinity of the substrate surface; and (b) generating a plasma in the gas by providing plasma-forming energy adjacent to the plastic substrate, thus forming a coating on the substrate surface by plasma enhanced chemical vapor deposition (PECVD).
The plasma-forming energy is applied in a first phase as a first pulse at a first energy level followed by further treatment in a second phase at a second energy level lower than the first energy level.
The invention further pertains to a substrate coated with the product of the above method, to a vessel processing system for coating of a vessel, the system comprising a processing station arrangement configured for performing the above and/or below mentioned method steps. Examples of such processing stations 5501-5504 are depicted in
The invention further pertains to a computer-readable medium, in which a computer program for coating of a vessel is stored which, when being executed by a processor of a vessel processing system, is adapted to instruct the processor to control the vessel processing system such that it carries out the above and/or below mentioned method steps.
The invention further pertains to a program element or computer program for coating of a vessel, which, when being executed by a processor of a vessel processing system, is adapted to instruct the processor to control the vessel processing system such that it carries out the above and/or below mentioned method steps.
The processor may thus be equipped to carry out exemplary embodiments of the methods of the present invention. The computer program may be written in any suitable programming language, for example, C++ and may be stored on the computer-readable medium, such as a CD-ROM. Also, the computer program may be available from a network, such as the Worldwide Web, from which it may be downloaded into image processing units or processors, or any suitable computers.
In the following, coating methods according to the invention and coated devices according to the invention which are made by these methods are described. The methods can be carried out on the equipment (vessel processing system and vessel holder) which is also described below.
The following reference characters are used in the drawing figures:
In the context of the present invention, the following definitions and abbreviations are used:
RF is radio frequency.
The term “at least” in the context of the present invention means “equal or more” than the integer following the term. The word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality unless indicated otherwise. Whenever a parameter range is indicated, it is intended to disclose the parameter values given as limits of the range and all values of the parameter falling within said range.
“First” and “second” or similar references to, e.g., processing stations or processing devices refer to the minimum number of processing stations or devices that are present, but do not necessarily represent the order or total number of processing stations and devices. These terms do not limit the number of processing stations or the particular processing carried out at the respective stations.
For purposes of the present invention, an “organosilicon precursor” is a compound having at least one of the linkage:
which is a tetravalent silicon atom connected to an oxygen or nitrogen atom and an organic carbon atom (an organic carbon atom being a carbon atom bonded to at least one hydrogen atom). A volatile organosilicon precursor, defined as such a precursor that can be supplied as a vapor in a PECVD apparatus, is an optional organosilicon precursor. Optionally, the organosilicon precursor is selected from the group consisting of a linear siloxane, a monocyclic siloxane, a polycyclic siloxane, a polysilsesquioxane, an alkyl trimethoxysilane, a linear silazane, a monocyclic silazane, a polycyclic silazane, a polysilsesquiazane, and a combination of any two or more of these precursors.
The feed amounts of PECVD precursors, gaseous reactant or process gases, and carrier gas are sometimes expressed in “standard volumes” in the specification and claims. The standard volume of a charge or other fixed amount of gas is the volume the fixed amount of the gas would occupy at a standard temperature and pressure (without regard to the actual temperature and pressure of delivery). Standard volumes can be measured using different units of volume, and still be within the scope of the present disclosure and claims. For example, the same fixed amount of gas could be expressed as the number of standard cubic centimeters, the number of standard cubic meters, or the number of standard cubic feet. Standard volumes can also be defined using different standard temperatures and pressures, and still be within the scope of the present disclosure and claims. For example, the standard temperature might be 0° C. and the standard pressure might be 760 Torr (as is conventional), or the standard temperature might be 20° C. and the standard pressure might be 1 Torr. But whatever standard is used in a given case, when comparing relative amounts of two or more different gases without specifying particular parameters, the same units of volume, standard temperature, and standard pressure are to be used relative to each gas, unless otherwise indicated.
The corresponding feed rates of PECVD precursors, gaseous reactant or process gases, and carrier gas are expressed in standard volumes per unit of time in the specification. For example, in the working examples the flow rates are expressed as standard cubic centimeters per minute, abbreviated as sccm. As with the other parameters, other units of time can be used, such as seconds or hours, but consistent parameters are to be used when comparing the flow rates of two or more gases, unless otherwise indicated.
A “vessel” in the context of the present invention can be any type of vessel with at least one opening and a wall defining an interior surface. The substrate can be the inside wall of a vessel having a lumen. Though the invention is not necessarily limited to vessels of a particular volume, vessels are contemplated in which the lumen has a void volume of from 0.5 to 50 mL, optionally from 1 to 10 mL, optionally from 0.5 to 5 mL, optionally from 1 to 3 mL. The substrate surface can be part or all of the inner surface of a vessel having at least one opening and an inner surface.
The term “at least” in the context of the present invention means “equal or more” than the integer following the term. Thus, a vessel in the context of the present invention has one or more openings. One or two openings, like the openings of a sample tube (one opening) or a syringe barrel (two openings) are preferred. If the vessel has two openings, they can be of same or different size. If there is more than one opening, one opening can be used for the gas inlet for a PECVD coating method according to the present invention, while the other openings are either capped or open. A vessel according to the present invention can be a syringe (or a part thereof, for example a syringe barrel) for storing or delivering a biologically active compound or composition, e.g. a medicament or pharmaceutical composition, a vial for storing biological materials or biologically active compounds or compositions, a pipe, e.g. a catheter for transporting biological materials or biologically active compounds or compositions, or a cuvette for holding fluids, e.g. for holding biological materials or biologically active compounds or compositions.
A vessel can be of any shape, a vessel having a substantially cylindrical wall adjacent to at least one of its open ends being preferred. Generally, the interior wall of the vessel is cylindrically shaped, like, e.g. in a sample tube or a syringe barrel. Sample tubes and syringes or their parts (for example syringe barrels) are contemplated.
A “hydrophobic layer” in the context of the present invention means that the coating lowers the wetting tension of a surface coated with the coating, compared to the corresponding uncoated surface. Hydrophobicity is thus a function of both the uncoated substrate and the coating. The same applies with appropriate alterations for other contexts wherein the term “hydrophobic” is used. The term “hydrophilic” means the opposite, i.e. that the wetting tension is increased compared to reference sample. The present hydrophobic layers are primarily defined by their hydrophobicity and the process conditions providing hydrophobicity, and optionally can have a composition according to the empirical composition or sum formula SiwOxCyHz. It generally has an atomic ratio SiwOxCyHz wherein w is 1, x is from about 0.5 to about 2.4, y is from about 0.6 to about 3, preferably w is 1, x is from about 0.5 to 1.5, and y is from 0.9 to 2.0, more preferably w is 1, x is from 0.7 to 1.2 and y is from 0.9 to 2.0. The atomic ratio can be determined by XPS (X-ray photoelectron spectroscopy). Taking into account the H atoms, which are not measured by XPS, the coating may thus in one aspect have the formula SiwOxCyHz, or its equivalent SiOxCyHz, for example where w is 1, x is from about 0.5 to about 2.4, y is from about 0.6 to about 3, and z is from about 2 to about 9 as measured by at least one of Rutherford backscattering spectrometry (RBS) and hydrogen forward scattering spectrometry (HFS), preferably RBS.
These values of w, x, y, and z are applicable to the empirical composition SiwOxCyHz throughout this specification. The values of w, x, y, and z used throughout this specification should be understood as ratios or an empirical formula (e.g. for a coating), rather than as a limit on the number or type of atoms in a molecule. For example, octamethylcyclotetrasiloxane, which has the molecular composition Si4O4C8H24, can be described by the following empirical formula, arrived at by dividing each of w, x, y, and z in the molecular formula by 4, the largest common factor: Si1O1C2H6. The values of w, x, y, and z are also not limited to integers. For example, (acyclic) octamethyltrisiloxane, molecular composition Si3O2C8H24, is reducible to Si1O0.67C2.67H8.
“Wetting tension” is a specific measure for the hydrophobicity or hydrophilicity of a surface. An optional wetting tension measurement method in the context of the present invention is ASTM D 2578 or a modification of the method described in ASTM D 2578. This method uses standard wetting tension solutions (called dyne solutions) to determine the solution that comes nearest to wetting a plastic film surface for exactly two seconds. This is the film's wetting tension. The procedure utilized is varied herein from ASTM D 2578 in that the substrates are not flat plastic films.
A “lubricity layer” according to the present invention is a coating which has a lower frictional resistance than the uncoated surface. In other words, it reduces the frictional resistance of the coated surface in comparison to a reference surface that is uncoated. The present lubricity layers are primarily defined by their lower frictional resistance than the uncoated surface and the process conditions providing lower frictional resistance than the uncoated surface.
“Frictional resistance” can be static frictional resistance and/or kinetic frictional resistance.
One of the optional embodiments of the present invention is a syringe part, e.g. a syringe barrel or plunger, coated with a lubricity layer. In this contemplated embodiment, the relevant static frictional resistance in the context of the present invention is the breakout force as defined herein, and the relevant kinetic frictional resistance in the context of the present invention is the plunger sliding force as defined herein. For example, the plunger sliding force as defined and determined herein is suitable to determine the presence or absence and the lubricity characteristics of a lubricity layer or coating in the context of the present invention whenever the coating is applied to any syringe or syringe part, for example to the inner wall of a syringe barrel. The breakout force is of particular relevance for evaluation of the coating effect on a prefilled syringe, i.e. a syringe which is filled after coating and can be stored for some time, e.g. several months or even years, before the plunger is moved again (has to be “broken out”).
The “plunger sliding force” (synonym to “glide force,” “maintenance force,” Fm, also used in this description) in the context of the present invention is the force required to maintain movement of a plunger in a syringe barrel, e.g. during aspiration or dispense. It can advantageously be determined using the ISO 7886-1:1993 test known in the art. A synonym for “plunger sliding force” often used in the art is “plunger force” or “pushing force”.
The “plunger breakout force” (synonym to “breakout force”, “break loose force”, “initiation force”, Fi, also used in this description) in the context of the present invention is the initial force required to move the plunger in a syringe, for example in a prefilled syringe.
Both “plunger sliding force” and “plunger breakout force” and methods for their measurement are described in more detail in subsequent parts of this description. These two forces can be expressed in N, lbs. or kg and all three units are used herein. These units correlate as follows: 1N=0.102 kg=0.2248 lbs. (pounds).
Sliding force and breakout force are sometimes used herein to describe the forces required to advance a stopper or other closure into a vessel, such as a medical sample tube or a vial, to seat the stopper in a vessel to close the vessel. Its use is analogous to use in the context of a syringe and its plunger, and the measurement of these forces for a vessel and its closure are contemplated to be analogous to the measurement of these forces for a syringe, except that at least in most cases no liquid is ejected from a vessel when advancing the closure to a seated position.
“Slidably” means that the plunger, closure, or other removable part is permitted to slide in a syringe barrel or other vessel.
DETAILED DESCRIPTIONThe present invention will now be described more fully, inter alia with reference to the accompanying drawings, in which several embodiments are shown. This invention can, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth here. Rather, these embodiments are examples of the invention, which has the full scope indicated by the language of the claims. Like numbers refer to like or corresponding elements throughout. The following disclosure relates to all embodiments unless specifically limited to a certain embodiment.
Referring to the drawings, a method for preparing a lubricity coating or layer 286 on a plastic substrate 280 such as the interior surface 254 of a vessel 268, 80, for example on its wall 280, is illustrated. When a vessel 268 is coated by the above coating method using PECVD, the coating method comprises several steps. A vessel 268 is provided having an open end, a closed end, and an interior surface. At least one gaseous reactant is introduced within the vessel 268. Plasma is formed within the vessel 268 under conditions effective to form a reaction product of the reactant, i.e. a coating, on the interior surface of the vessel 268.
Apparatus and general conditions suitable for carrying out this method are described in U.S. Pat. No. 7,985,188, which is incorporated here by reference in full.
The method includes providing a gas including an organosilicon precursor, optionally an oxidizing gas (for example O2), and an inert gas in the vicinity of the substrate surface. The inert gas optionally is a noble gas, for example argon, helium, krypton, xenon, neon, or a combination of two or more of these inert gases. Plasma is generated in the gas by providing plasma-forming energy adjacent to the plastic substrate. As a result, a lubricity coating or layer 286 is formed on the substrate surface such as 254 by plasma enhanced chemical vapor deposition (PECVD). The plasma-forming energy is applied in a first phase as a first pulse at a first energy level, followed by further treatment in a second phase at a second energy level lower than the first energy level. Optionally, the second phase is applied as a second pulse.
VesselIn any embodiment, the substrate optionally can be injection molded, blow molded, or otherwise formed from a polymer selected from the group consisting of a polycarbonate, an olefin polymer, for example a cyclic olefin copolymer (COC), a cyclic olefin polymer (COP), or polypropylene, and preferably COP; a polyester, for example polyethylene terephthalate or polyethylene naphthalate; polylactic acid; a polymethylmethacrylate; or a combination of any two or more of these.
Another embodiment is a vessel 80, 268 including a barrier coating 288 and a closure 258, as well as a cap 262. The vessel 268 is generally tubular and made of thermoplastic material. The vessel 268 has a mouth or back end 256 and a lumen 274 bounded at least in part by a wall 280 having an inner surface interfacing with the lumen. There is an at least essentially continuous barrier coating 285 on the inner surface of the wall. A closure 258 covers the mouth and isolates the lumen of the vessel 268 from ambient air.
The vessel 268, 80 can also be made, for example of glass of any type used in medical or laboratory applications, such as soda-lime glass, borosilicate glass, or other glass formulations. Other vessels having any shape or size, made of any material, are also contemplated for use in the system 20. One function of coating a glass vessel can be to reduce the ingress of ions in the glass, either intentionally or as impurities, for example sodium, calcium, or others, from the glass to the contents of the vessel, such as a reagent or blood in an evacuated blood collection tube. Another function of coating a glass vessel in whole or in part, such as selectively at surfaces contacted in sliding relation to other parts, is to provide lubricity to the coating, for example to ease the insertion or removal of a stopper or passage of a sliding element such as a piston in a syringe. Still another reason to coat a glass vessel is to prevent a reagent or intended sample for the vessel, such as blood, from sticking to the wall of the vessel or an increase in the rate of coagulation of the blood in contact with the wall of the vessel.
A related embodiment is a vessel made of plastic, in which the barrier coating is made of soda lime glass, borosilicate glass, or another type of glass.
In any embodiment, the container size optionally can be from 1 to 10 mL, alternatively from 1 to 3 mL, alternatively from 6 to 10 mL.
One optional type of vessel 268 is a syringe including a plunger, a syringe barrel, and a lubricity coating as defined above on either one or both of these syringe parts, preferably on the inside wall of the syringe barrel. The syringe barrel includes a barrel having an interior surface slidably receiving the plunger. The lubricity coating may be disposed on the interior surface of the syringe barrel, or on the plunger surface contacting the barrel, or on both surfaces. The lubricity coating is effective to reduce the breakout force or the plunger sliding force necessary to move the plunger within the barrel.
The syringe optionally further includes a staked needle 7122. The needle is hollow with a typical size ranging from 18-29 gauge. The syringe barrel 250 has an interior surface slidably receiving the plunger. The staked needle may be affixed to the syringe during the injection molding of the syringe or may be assembled to the formed syringe using an adhesive. A cover 7126 is placed over the staked needle to seal the syringe assembly. The syringe assembly must be sealed so that a vacuum can be maintained within the syringe to enable the PECVD coating process.
As another option, the syringe can comprise a Luer fitting at its front end 260. The syringe barrel has an interior surface slidably receiving the plunger. The Luer fitting includes a Luer taper having an internal passage defined by an internal surface. The Luer fitting optionally can be formed as a separate piece from the syringe barrel and joined to the syringe barrel by a coupling.
Another aspect of the invention is a plunger for a syringe, including a piston 258, 7166 and a push rod. The piston has a front face, a generally cylindrical side face, and a back portion, the side face being configured to movably seat within a syringe barrel. The plunger has a lubricity coating according to the present invention on its side face. The push rod engages the back portion of the piston and is configured for advancing the piston in a syringe barrel. The plunger may additionally comprise an SiOx coating.
A further aspect of the invention is a vessel with just one opening, which can be, for example, a vessel for collecting or storing a compound or composition. Such vessel is in a specific aspect a tube, e.g. a sample collecting tube, e.g., a blood collecting tube. Such a tube may be closed with a closure, e.g. a cap or stopper. Such cap or stopper may comprise a lubricity coating according to the present invention on its surface which is in contact with the tube, and/or it may contain a passivating coating according to the present invention on its surface facing the lumen of the tube. In a specific aspect, such a stopper or a part thereof may be made from an elastomeric material.
A further particular aspect of the invention is a syringe barrel coated with the lubricity coating as defined in the preceding paragraph.
Gas Feed to PECVD Apparatus for Depositing Lubricity CoatingA precursor is included in the gas feed provided to the PECVD apparatus. Preferably, the precursor is an organosilicon compound (in the following also designated as “organosilicon precursor”), more preferably an organosilicon compound selected from the group consisting of a linear siloxane, a monocyclic siloxane, a polycyclic siloxane, a polysilsesquioxane, an alkyl trimethoxysilane, an aza analogue of any of these precursors (i.e. a linear silazane, a monocyclic silazane, a polycyclic silazane, a polysilsesquioxazane), and a combination of any two or more of these precursors. The precursor is applied to a substrate under conditions effective to form a coating by PECVD. The precursor is thus polymerized, crosslinked, partially or fully oxidized, or any combination of these. In any embodiment, the organosilicon precursor optionally can include a linear or monocyclic siloxane, optionally comprising or consisting essentially of octamethylcyclotetrasiloxane (OMCTS), tetramethylcyclotetrasiloxane (TMCTS), hexamethyldisiloxane (HMDSO), tetramethyldisiloxane (TMDSO), or a combination of two or more of these.
The oxidizing gas can comprise or consist of oxygen (O2 and/or O3, the latter commonly known as ozone), nitrous oxide, or any other gas that oxidizes the precursor during PECVD at the conditions employed. The oxidizing gas comprises about 1 standard volume of oxygen. The gaseous reactant or process gas can be at least substantially free of nitrogen. In any embodiment. O2 optionally can be present, preferably in a volume-volume ratio to the organosilicon precursor of from 0:1 to 2:1, optionally from 0:1 to 0.5:1, optionally from 0.01:1 to 1:1, optionally from 0.01:1 to 0.5:1, optionally from 0.1:1 to 1:1.
In any embodiment, Ar optionally can be present as the inert gas. The gas optionally can be from 1 to 6 standard volumes of the organosilicon precursor, from 1 to 100 standard volumes of the inert gas, and from 0.1 to 2 standard volumes of O2. In any embodiment, both Ar and O2 optionally can be present.
The method of the invention may comprise the application of one or more coatings made by PECVD from the same or different organosilicon precursors under the same or different reaction conditions. E.g. s syringe may first be coated with an SiOx barrier coating using HMDSO as organosilicon precursor, and subsequently with a lubricity coating using OMCTS as organosilicon precursor.
A gaseous reactant or process gas can be employed having a standard volume ratio of, for example when a lubricity coating is prepared:
-
- from 1 to 6 standard volumes, optionally from 2 to 4 standard volumes, optionally equal to or less than 6 standard volumes, optionally equal to or less than 2.5 standard volumes, optionally equal to or less than 1.5 standard volumes, optionally equal to or less than 1.25 standard volumes of the precursor;
- from 1 to 100 standard volumes, optionally from 5 to 100 standard volumes, optionally from 10 to 70 standard volumes, of a carrier gas;
- from 0.1 to 2 standard volumes, optionally from 0.2 to 1.5 standard volumes, optionally from 0.2 to 1 standard volumes, optionally from 0.5 to 1.5 standard volumes, optionally from 0.8 to 1.2 standard volumes of an oxidizing agent.
PECVD may be carried out at any suitable pressure or vacuum level. For example, the process pressure can be from 0.001 to 100 Torr (from 0.13 Pa to 13,000 Pa), optionally from 0.01 to 10 Torr (from 1.3 to 1300 Pa), optionally from 0.1 to 10 Torr (from 13 to 1300 Pa).
First Phase of Plasma Forming Energy for Depositing Lubricity CoatingIn any embodiment, the plasma optionally can be generated with microwave energy or RF energy. The plasma optionally can be generated with electrodes powered at a radio frequency, preferably at a frequency of from 10 kHz to less than 300 MHz, more preferably of from 1 to 50 MHz, even more preferably of from 10 to 15 MHz, most preferably at 13.56 MHz.
In any embodiment, the first pulse energy can be, for example, from 21 to 100 Watts, alternatively from 25 to 75 Watts; alternatively from 40 to 60 Watts. The following first pulse energy ranges are alternatively contemplated: from 21 to 50 Watts; alternatively from 22 to 50 Watts; alternatively from 23 to 50 Watts; alternatively from 24 to 50 Watts; alternatively from 25 to 50 Watts; alternatively from 26 to 50 Watts; alternatively from 27 to 50 Watts; alternatively from 28 to 50 Watts; alternatively from 29 to 50 Watts; alternatively from 30 to 50 Watts; alternatively from 31 to 50 Watts; alternatively from 32 to 50 Watts; alternatively from 33 to 50 Watts; alternatively from 34 to 50 Watts; alternatively from 35 to 50 Watts; alternatively from 36 to 50 Watts; alternatively from 37 to 50 Watts; alternatively from 38 to 50 Watts; alternatively from 39 to 50 Watts; alternatively from 40 to 50 Watts; alternatively from 41 to 50 Watts; alternatively from 42 to 50 Watts; alternatively from 43 to 50 Watts; alternatively from 44 to 50 Watts; alternatively from 45 to 50 Watts; alternatively from 46 to 50 Watts; alternatively from 47 to 50 Watts; alternatively from 48 to 50 Watts; alternatively from 49 to 50 Watts; alternatively from 50 to 100 Watts; alternatively from 51 to 100 Watts; alternatively from 52 to 100 Watts; alternatively from 53 to 100 Watts; alternatively from 54 to 100 Watts; alternatively from 55 to 100 Watts; alternatively from 56 to 100 Watts; alternatively from 57 to 100 Watts; alternatively from 58 to 100 Watts; alternatively from 59 to 100 Watts; alternatively from 60 to 100 Watts; alternatively from 61 to 100 Watts; alternatively from 62 to 100 Watts; alternatively from 63 to 100 Watts; alternatively from 64 to 100 Watts; alternatively from 65 to 100 Watts; alternatively from 66 to 100 Watts; alternatively from 67 to 100 Watts; alternatively from 68 to 100 Watts; alternatively from 69 to 100 Watts; alternatively from 70 to 100 Watts; alternatively from 71 to 100 Watts; alternatively from 72 to 100 Watts; alternatively from 73 to 100 Watts; alternatively from 74 to 100 Watts; alternatively from 75 to 100 Watts; alternatively from 76 to 100 Watts; alternatively from 77 to 100 Watts; alternatively from 78 to 100 Watts; alternatively from 79 to 100 Watts; alternatively from 80 to 100 Watts; alternatively from 81 to 100 Watts; alternatively from 82 to 100 Watts; alternatively from 83 to 100 Watts; alternatively from 84 to 100 Watts; alternatively from 85 to 100 Watts; alternatively from 86 to 100 Watts; alternatively from 87 to 100 Watts; alternatively from 88 to 100 Watts; alternatively from 89 to 100 Watts; alternatively from 90 to 100 Watts; alternatively from 91 to 100 Watts; alternatively from 92 to 100 Watts; alternatively from 93 to 100 Watts; alternatively from 94 to 100 Watts; alternatively from 95 to 100 Watts; alternatively from 96 to 100 Watts; alternatively from 97 to 100 Watts; alternatively from 98 to 100 Watts; alternatively from 99 to 100 Watts; alternatively; alternatively from 21 to 99 Watts; alternatively from 21 to 98 Watts; alternatively from 21 to 97 Watts; alternatively from 21 to 96 Watts; alternatively from 21 to 95 Watts; alternatively from 21 to 94 Watts; alternatively from 21 to 93 Watts; alternatively from 21 to 92 Watts; alternatively from 21 to 91 Watts; alternatively from 21 to 90 Watts; alternatively from 21 to 89 Watts; alternatively from 22 to 88 Watts; alternatively from 23 to 87 Watts; alternatively from 24 to 86 Watts; alternatively from 25 to 85 Watts; alternatively from 21 to 84 Watts; alternatively from 21 to 83 Watts; alternatively from 21 to 82 Watts; alternatively from 21 to 81 Watts; alternatively from 21 to 80 Watts; alternatively from 21 to 79 Watts; alternatively from 22 to 78 Watts; alternatively from 23 to 77 Watts; alternatively from 24 to 76 Watts; alternatively from 26 to 74 Watts; alternatively from 27 to 73 Watts; alternatively from 28 to 72 Watts; alternatively from 29 to 71 Watts; alternatively from 30 to 70 Watts; alternatively from 31 to 69 Watts; alternatively from 32 to 68 Watts; alternatively from 33 to 67 Watts; alternatively from 34 to 66 Watts; alternatively from 35 to 65 Watts; alternatively from 36 to 64 Watts; alternatively from 37 to 63 Watts; alternatively from 38 to 62 Watts; alternatively from 39 to 61 Watts; alternatively from 41 to 59 Watts; alternatively from 42 to 58 Watts; alternatively from 43 to 57 Watts; alternatively from 44 to 56 Watts; alternatively from 45 to 55 Watts; alternatively from 46 to 54 Watts; alternatively from 47 to 53 Watts; alternatively from 48 to 52 Watts; alternatively from 49 to 51 Watts; alternatively 50 Watts.
In any embodiment, the ratio of the electrode power to the plasma volume for the first pulse optionally can be equal to or more than 5 W/ml, preferably is from 6 W/ml to 150 W/ml, more preferably is from 7 W/ml to 100 W/ml, most preferably from 7 W/ml to 20 W/ml.
In any embodiment, the first pulse optionally can be applied for 0.1 to 5 seconds, alternatively 0.5 to 3 seconds, alternatively 0.75 to 1.5 seconds. The first phase energy level optionally can be applied in at least two pulses. The second pulse is at a lower energy level than the first pulse. As a further option, the first phase energy level optionally can be applied in at least three pulses. The third pulse optionally can be at a lower energy level than the second pulse.
Second Phase of Plasma Forming Energy for Depositing Lubricity CoatingIn any embodiment, the second phase energy level optionally can be from 0.1 to 25 Watts, alternatively from 0.5 to 3 Watts, alternatively from 1 to 10 Watts, alternatively from 2 to 5 Watts.
Relation Between First and Second Phases for Depositing Lubricity CoatingIn any embodiment, the plasma-forming energy optionally can be applied in the first phase as a first pulse at a first energy level, followed by further treatment in a second phase at a second energy level.
Additional PECVD TreatmentIn any embodiment, the contemplated method optionally includes a step for preparing a barrier coating an optional coating 285 on the substrate before the lubricity coating 286 is applied. The additional step optionally includes introducing a gas comprising an organosilicon precursor and O2 in the vicinity of the substrate surface and generating plasma from the gas, thus forming an SiOx barrier coating on the substrate surface by plasma enhanced chemical vapor deposition (PECVD). Optionally, in the step for preparing a barrier coating, the plasma can be generated with electrodes powered with sufficient power to form an SiOx barrier coating on the substrate surface. The electrodes optionally are supplied with an electric power of from 8 to 500 W, preferably from 20 to 400 W, more preferably from 35 to 350 W, even more preferably of from 44 to 300 W, most preferably of from 44 to 70 W. In any embodiment of barrier coating, the O2 optionally can be present in a volume:volume ratio of from 1:1 to 100:1 in relation to the silicon containing precursor, preferably in a ratio of from 5:1 to 30:1, more preferably in a ratio of from 10:1 to 20:1, even more preferably in a ratio of 15:1.
Another expedient contemplated here, for adjacent layers of SiOx and a lubricity layer or coating and/or hydrophobic layer, is a graded composite of SiwOxCyHz, as defined in the Definition Section. A graded composite can be separate layers of a lubricity layer or coating and/or hydrophobic layer or coating and SiOx with a transition or interface of intermediate composition between them, or separate layers of a lubricity layer or coating and/or hydrophobic layer or coating and SiOx with an intermediate distinct layer or coating of intermediate composition between them, or a single layer or coating that changes continuously or in steps from a composition of a lubricity layer or coating and/or hydrophobic layer or coating to a composition more like SiOx, going through the coating in a normal direction.
The grade in the graded composite can go in either direction. For example, a lubricity layer or coating and/or hydrophobic layer or coating can be applied directly to the substrate and graduate to a composition further from the surface of SiOx. Or, the composition of SiOx can be applied directly to the substrate and graduate to a composition further from the surface of a lubricity layer or coating and/or hydrophobic layer. A graduated coating is particularly contemplated if a coating of one composition is better for adhering to the substrate than the other, in which case the better-adhering composition can, for example, be applied directly to the substrate. It is contemplated that the more distant portions of the graded coating can be less compatible with the substrate than the adjacent portions of the graded coating, since at any point the coating is changing gradually in properties, so adjacent portions at nearly the same depth of the coating have nearly identical composition, and more widely physically separated portions at substantially different depths can have more diverse properties. It is also contemplated that a coating portion that forms a better barrier against transfer of material to or from the substrate can be directly against the substrate, to prevent the more remote coating portion that forms a poorer barrier from being contaminated with the material intended to be barred or impeded by the barrier.
The coating, instead of being graded, optionally can have sharp transitions between one layer or coating and the next, without a substantial gradient of composition. Such coatings can be made, for example, by providing the gases to produce a layer or coating as a steady state flow in a non-plasma state, then energizing the system with a brief plasma discharge to form a coating on the substrate. If a subsequent coating is to be applied, the gases for the previous coating are cleared out and the gases for the next coating are applied in a steady-state fashion before energizing the plasma and again forming a distinct layer or coating on the surface of the substrate or its outermost previous coating, with little if any gradual transition at the interface.
Post-TreatmentOptionally, after the lubricity layer or coating is applied, it can be post-cured after the PECVD process. Radiation curing approaches, including UV-initiated (free radial or cationic), electron-beam (E-beam), and thermal as described in Development Of Novel Cycloaliphatic Siloxanes For Thermal And UV-Curable Applications (Ruby Chakraborty Dissertation, can 2008) be utilized. For example, in any embodiment, the lubricity coated container optionally can be further treated by post heating it, optionally at 50 to 110 degrees C., alternatively 80 to 100 degree C., optionally for a time interval of 1 to 72 hours, alternatively 4 to 48 hours, alternatively 8 to 32 hours, alternatively 20 to 30 hours. In any embodiment, the post heating step optionally can be carried out under at least partial vacuum, alternatively under a pressure of less than 50 Torr, alternatively under a pressure of less than 10 Torr, optionally under a pressure of less than 5 Torr, alternatively at a pressure of less than 1 Torr.
PropertiesIn any embodiment, the result of the present treatment can be a coated substrate coated with a lubricity coating. The lubricity coating optionally can have an average thickness of from 1 to 5000 nm, alternatively from 30 to 1000 nm, as another alternative from 100 to 500 nm. The optional SiOx barrier coating or layer of any embodiment optionally can have a thickness of from 20 to 30 nm.
These ranges are representing average thicknesses, as a certain roughness may enhance the lubricious properties of the lubricity coating. Thus its thickness is advantageously not uniform throughout the coating (see below). However, a uniformly thick lubricity coating is also considered.
The absolute thickness of the lubricity coating at single measurement points can be higher or lower than the range limits of the average thickness, with maximum deviations of preferably +/−50%, more preferably +/−25% and even more preferably +/−15% from the average thickness. However, it typically varies within the thickness ranges given for the average thickness in this description.
The thickness of this and other coatings can be measured, for example, by transmission electron microscopy (TEM). An exemplary TEM image for a lubricity coating is shown in
The TEM can be carried out, for example, as follows. Samples can be prepared for Focused Ion Beam (FIB) cross-sectioning in two ways. Either the samples can be first coated with a thin layer or coating of carbon (50-100 nm thick) and then coated with a sputtered layer or coating of platinum (50-100 nm thick) using a K575X Emitech coating system, or the samples can be coated directly with the protective sputtered Pt layer. The coated samples can be placed in an FEI FIB200 FIB system. An additional layer or coating of platinum can be FIB-deposited by injection of an oregano-metallic gas while rastering the 30 kV gallium ion beam over the area of interest. The area of interest for each sample can be chosen to be a location half way down the length of the syringe barrel. Thin cross sections measuring approximately 15 μm (“micrometers”) long, 2 μm wide and 15 μm deep can be extracted from the die surface using a proprietary in-situ FIB lift-out technique. The cross sections can be attached to a 200 mesh copper TEM grid using FIB-deposited platinum. One or two windows in each section, measuring ˜8 μm wide, can be thinned to electron transparency using the gallium ion beam of the FEI FIB.
Cross-sectional image analysis of the prepared samples can be performed utilizing either a Transmission Electron Microscope (TEM), or a Scanning Transmission Electron Microscope (STEM), or both. All imaging data can be recorded digitally. For STEM imaging, the grid with the thinned foils can be transferred to a Hitachi HD2300 dedicated STEM. Scanning transmitted electron images can be acquired at appropriate magnifications in atomic number contrast mode (ZC) and transmitted electron mode (TE). The following instrument settings can be used.
For TEM analysis the sample grids can be transferred to a Hitachi HF2000 transmission electron microscope. Transmitted electron images can be acquired at appropriate magnifications. The relevant instrument settings used during image acquisition can be those given below.
In any embodiment, optionally, the resulting lubricity coating optionally can have an atomic ratio SiwOxCyHz or Siw(NH)xCyHz wherein w is 1, x is from about 0.5 to about 2.4, y is from about 0.6 to about 3.
The roughness of the lubricity coating is increased with decreasing power (in Watts) energizing the plasma, and by the presence of O2 in the amounts described above. The roughness can be expressed as “RMS roughness” or “RMS” determined by AFM. RMS is the standard deviation of the difference between the highest and lowest points in an AFM image (the difference is designated as “Z”). It is calculated according to the formula:
Rq={Σ(Z1−Zavg)2/N}−2
where Zavg is the average Z value within the image; Z1 is the current value of Z; and N is the number of points in the image.
The RMS range in this specific embodiment is typically from 7 to 20 nm, preferably from 12 to 20 nm, optionally from 13 to 17 nm, optionally from 13 to 15 nm. A lower RMS can, however, still lead to satisfying lubricity properties. Alternatively, the resulting coating optionally can have a roughness when determined by AFM and expressed as RMS of from more than 0 to 25 nm,
The coated substrate of any embodiment optionally can have a lower wetting tension than the uncoated surface, optionally a wetting tension of from 20 to 72 dyne/cm, optionally a wetting tension of from 30 to 60 dynes/cm, optionally a wetting tension of from 30 to 40 dynes/cm, optionally 34 dyne/cm. Optionally the coated substrate is more hydrophobic than the uncoated surface.
Optionally, the lubricity coating is a passivating coating, for example a hydrophobic coating resulting, e.g., in a lower precipitation of components of a composition in contact with the coated surface.
The plasma-forming energy optionally applied in the first phase optionally reduces the breakout force, Fi, of a syringe, compared to the breakout force of a similar syringe that has only been treated at the second energy level. The lubricity coating also has a lower frictional resistance Fi than the uncoated surface. Optionally, the frictional resistance Fi is reduced by at least 25%, or by at least 45%, or by at least 60% in comparison to the uncoated surface. Plunger sliding force can be measured, for example, as provided in the ISO 7886-1:1993 test. In order to achieve a sufficient lubricity (e.g. to ensure that a syringe plunger can be moved in the syringe, but to avoid uncontrolled movement of the plunger), the following ranges of Fi and Fm can advantageously be maintained:
-
- F1: 2.5 to 15 N;
- Fm: 2.5 to 25 N.
The coated vessel 268 of any embodiment optionally can be a syringe comprising a barrel and a piston or plunger. The piston or plunger can have an outer surface engaging the inner surface of the barrel. At least one of the inner surface and outer surface can be a coated substrate according to any embodiment.
In a syringe of any embodiment, the plunger initiation force Fi optionally can be from 2.5 to 15 N and the plunger maintenance force Fm optionally can be from 2.5 to 25 N after 1 week.
In a syringe of any embodiment, the lubricity coating optionally can have the atomic ratio SiwOxCyHz or Siw(NH)xCyHz wherein w is 1, x is from about 0.5 to about 2.4, y is from about 0.6 to about 3.
In a syringe of any embodiment, the lubricity coating optionally can have an average thickness of from 10 to 1000 nm.
The syringe or a syringe part in any embodiment optionally can be made according to any of the methods described in this specification. In an optional combination of features, the plastic substrate can be made of COC or COP, the gas can include octamethylcyclotetrasiloxane, O2 and Ar, and the power for generating the plasma, in relation to the volume of the syringe lumen, can be from 6 W/ml to 0.1 W/ml.
The syringe in any embodiment optionally can contain a compound or composition in its lumen, preferably a biologically active compound or composition or a biological fluid, for example: (i) citrate or a citrate containing composition, (ii) a medicament, for example insulin or an insulin containing composition, or (iii) blood or blood cells.
For example, the present invention provides a method for setting the lubricity properties of a coating on a substrate surface, the method comprising the steps: (a) providing a gas comprising an organosilicon precursor and optionally O2 and optionally an inert gas (e.g. Argon) in the vicinity of the substrate surface; and (b) generating a plasma from the gas by providing plasma-forming energy adjacent to the plastic substrate, thus forming a coating on the substrate surface by plasma enhanced chemical vapor deposition (PECVD). The lubricity characteristics of the coating are set by setting the ratio of the O2 to the organosilicon precursor in the gaseous reactant, and/or by setting the electric power used for generating the plasma, and/or by setting the ratio of the noble gas to the organosilicon precursor.
Barrier Coating or LayerIn a further aspect of the invention, the coating further comprises a barrier coating, for example an SiOx coating. Typically, the barrier is against a gas or liquid, preferably against water vapor, oxygen and/or air. The barrier may also be used for establishing and/or maintaining a vacuum inside a vessel 268 coated with the barrier coating, e.g. inside a blood collection tube. In any embodiment, the coated substrate optionally can include at least one layer of SiOx, wherein x is from 1.5 to 2.9, which optionally functions as a gas barrier coating.
The lubricity coating optionally can be situated between the SiOx layer and the substrate surface, or vice versa. The lubricity coating of present invention can optionally be applied onto an SiOx barrier coating. This is shown in
In any embodiment a vessel processing system 20 is contemplated for coating a vessel 80.
The first vessel processing station 5501 contains a vessel holder 38 which holds a seated vessel 268, 80. The vessel may also be a syringe body, a vial, a catheter or, for example, a pipette. The vessel may, for example, be made of glass or plastic. In case of plastic vessels, the first processing station may also comprise a mold for molding the plastic vessel.
After the first processing at the first processing station (which processing may comprise coating of the interior surface of the vessel, the vessel holder 38 may be transported together with the vessel 82 to the second vessel processing station 5502. This transportation is performed by a conveyor arrangement 70, 72, 74. For example, a gripper or several grippers may be provided for gripping the vessel holder 38 and/or the vessel 80 in order to move the vessel/holder combination to the next processing station 5502. Alternatively, only the vessel may be moved without the holder. However, it may be advantageous to move the holder together with the vessel in which case the holder is adapted such that it can be transported by the conveyor arrangement.
In any embodiment, a computer-readable medium is contemplated, in which a computer program for coating of a vessel 80 optionally can be stored. The program, when being executed by a processor of a vessel processing system 20, optionally can be adapted to instruct the processor to control the vessel processing system such that it carries out the contemplated method.
In any embodiment, a program element is contemplated for coating of a vessel 80. The program element optionally can be executed by a processor of a vessel processing system 20. The program element optionally can be adapted to instruct the processor to control the vessel processing system such that it carries out the contemplated method.
A vessel can be moved from a stock to the left processing station 5504. Alternatively, the vessel can be molded in the first processing station 5504. In any case, a first vessel processing is performed in the processing station 5504, such as a molding, an inspection and/or a coating, which may be followed by a second inspection. Then, the vessel is moved to the next processing station 5501 via the conveyor arrangement 70, 72, 74. Typically, the vessel is moved together with the vessel holder. A second processing is performed in the second processing station 5501 after which the vessel and holder are moved to the next processing station 5502 in which a third processing is performed. The vessel is then moved (again together with the holder) to the fourth processing station 5503 for a fourth processing, after which it is conveyed to a storage.
Before and after each coating step or molding step or any other step which manipulates the vessel an inspection of the whole vessel, of part of the vessel and in particular of an interior surface of the vessel may be performed. The result of each inspection can be transferred to a central processing unit 5505 via a data bus 5507. Each processing station is connected to the data bus 5507. The above described program element may run on the processor 5505, and the processor, which may be adapted in form of a central control and regulation unit, controls the system and may also be adapted to process the inspection data, to analyze the data and to determine whether the last processing step was successful.
If it is determined that the last processing step was not successful, because for example the coating comprises holes or because the surface of the coating is determined to be regular or not smooth enough, the vessel does not enter the next processing station but is either removed from the production process (see conveyor sections 7001, 7002, 7003, 7004) or conveyed back in order to become re-processed.
The processor 5505 may be connected to a user interface 5506 for inputting control or regulation parameters.
The electrode and the detector 5702 may be adapted to be moved into the interior space of the vessel 80 when the vessel is seated on the holder 38.
The optical inspection may be particularly performed during a coating step, for example with the help of optical detectors 5703, 5704 which are arranged outside the seated vessel 80 or even with the help of an optical detector 5705 arranged inside the interior space of the vessel 80.
The detectors may comprise color filters such that different wavelengths can be detected during the coating process. The processing unit 5505 analyzes the optical data and determines whether the coating was successful or not to a predetermined level of certainty. If it is determined that the coating was most probably unsuccessful, the respective vessel is separated from the processing system or re-processed.
ProductThe coated vessel of the invention may be empty, evacuated or (pre)filled with a compound or composition. One contemplated embodiment is a prefilled syringe, e.g. a syringe prefilled with a medicament, a diagnostic compound or composition, or any other biologically of chemically active compound or composition which is intended to be dispensed using the syringe.
The PECVD made coatings and PECVD coating methods using an organosilicon precursor described in this specification are also useful for coating catheters or cuvettes to form a barrier coating, a hydrophobic coating, a lubricity coating, or more than one of these. A cuvette is a small tube of circular or square cross section, sealed at one end, made of a polymer, glass, or fused quartz (for UV light) and designed to hold samples for spectroscopic experiments. The best cuvettes are as clear as possible, without impurities that might affect a spectroscopic reading. Like a test tube, a cuvette may be open to the atmosphere or have a cap to seal it shut. The PECVD-applied coatings of the present invention can be very thin, transparent, and optically flat, thus not interfering with optical testing of the cuvette or its contents.
Lubricity ProfileThe lubricity coating optionally provides a consistent plunger force that reduces the difference between the break loose force (Fi) and the glide force (Fm). These two forces are important performance measures for the effectiveness of a lubricity coating. For Fi and Fm, it is desired to have a low, but not too low value. With too low Fi, which means a too low level of resistance (the extreme being zero), premature/unintended flow may occur, which might e.g. lead to an unintentional premature or uncontrolled discharge of the content of a prefilled syringe.
Further advantageous Fi and Fm values can be found in the Tables of the Examples. Lower Fi and Fm values can be achieved than the ranges indicated above. Coatings having such lower values are also considered to be encompassed by the present invention.
Break-loose and glide forces are important throughout a device's shelf life especially in automated devices such as auto-injectors. Changes in break-loose and/or glide forces can lead to misfiring of auto injectors.
In a very particular aspect of the present invention, the lubricity is influenced by the roughness of the lubricity coating. It has surprisingly been found that a rough surface of the coating is correlated with enhanced lubricity. The roughness of the lubricity coating is increased with decreasing power (in Watts) energizing the plasma, and by the presence of O2 in the amounts described above.
The vessels (e.g. syringe barrels and/or plungers) coated with a lubricity coating according to present invention have a higher lubricity, which means a lower Fi and/or Fm (determined, e.g. by measuring the Fi and/or Fm) than the uncoated vessels. They also have a higher lubricity than vessels coated with an SiOx coating as described herein at the external surface.
Another aspect of the invention is a lubricity layer or coating deposited by PECVD from a feed gas comprising a monocyclic siloxane, a monocyclic silazane, a polycyclic siloxane, a polycyclic silazane, or any combination of two or more of these. The coating has an atomic concentration of carbon, normalized to 100% of carbon, oxygen, and silicon, as determined by X-ray photoelectron spectroscopy (XPS), greater than the atomic concentration of carbon in the atomic formula for the feed gas.
Optionally, the atomic concentration of carbon increases by from 1 to 80 atomic percent (as calculated and based on the XPS conditions in Example 15 of EP 2 251 455), alternatively from 10 to 70 atomic percent, alternatively from 20 to 60 atomic percent, alternatively from 30 to 50 atomic percent, alternatively from 35 to 45 atomic percent, alternatively from 37 to 41 atomic percent in relation to the atomic concentration of carbon in the organosilicon precursor when a lubricity coating is made.
An additional aspect of the invention is a lubricity layer or coating deposited by PECVD from a feed gas comprising a monocyclic siloxane, a monocyclic silazane, a polycyclic siloxane, a polycyclic silazane, or any combination of two or more of these. The coating has an atomic concentration of silicon, normalized to 100% of carbon, oxygen, and silicon, as determined by X-ray photoelectron spectroscopy (XPS), less than the atomic concentration of silicon in the atomic formula for the feed gas. See Example 15 of EP 2 251 455.
Optionally, the atomic concentration of silicon decreases by from 1 to 80 atomic percent (as calculated and based on the XPS conditions in Example 15 of EP 2251 455), alternatively from 10 to 70 atomic percent, alternatively from 20 to 60 atomic percent, alternatively from 30 to 55 atomic percent, alternatively from 40 to 50 atomic percent, alternatively from 42 to 46 atomic percent.
The lubricity coating can have a density between 1.25 and 1.65 g/cm3, alternatively between 1.35 and 1.55 g/cm3, alternatively between 1.4 and 1.5 g/cm3, alternatively between 1.4 and 1.5 g/cm3, alternatively between 1.44 and 1.48 g/cm3, as determined by X-ray reflectivity (XRR).
X-Ray Photoelectron Spectroscopy (XPS) ProtocolXPS data is quantified using relative sensitivity factors and a model that assumes a homogeneous layer. The analysis volume is the product of the analysis area (spot size or aperture size) and the depth of information. Photoelectrons are generated within the X-ray penetration depth (typically many microns), but only the photoelectrons within the top three photoelectron escape depths are detected. Escape depths are on the order of 15-35 Å, which leads to an analysis depth of ˜50-100 Å. Typically, 95% of the signal originates from within this depth.
The following analytical parameters are used:
-
- Instrument: PHI Quantum 2000
- X-ray source: Monochromated Alka 1486.6 eV
- Acceptance Angle ±23°
- Take-off angle 45°
- Analysis area 600 μm
- Charge Correction C1s 284.8 eV
- Ion Gun Conditions Ar+, 1 keV, 2×2 mm raster
- Sputter Rate 15.6 Å/min (SiO2 Equivalent)
Values given are normalized to 100 percent using the elements detected. Detection limits are approximately 0.05 to 1.0 atomic percent.
RBS spectra are acquired at a backscattering angle of 160° and an appropriate grazing angle (with the sample oriented perpendicular to the incident ion beam). The sample is rotated or tilted with a small angle to present a random geometry to the incident beam. This avoids channeling in both the film and the substrate. The use of two detector angles can significantly improve the measurement accuracy for composition when thin surface layers need to be analyzed.
When a thin (<100 nm) amorphous or polycrystalline film resides on a single crystal substrate “ion channeling” may be utilized to reduce the backscattering signal from the substrate. This results in improved accuracy in the composition of layers containing elements that overlay with the substrate signal, typically light elements such as oxygen, nitrogen and carbon.
Analytical Parameters: RBSHe++ Ion Beam Energy 2.275 MeV
Normal Detector Angle 160°
Grazing Detector Angle ˜100°
Analysis Mode CC RR
Spectra are fit by applying a theoretical layer model and iteratively adjusting elemental concentrations and thickness until good agreement is found between the theoretical and the experimental spectra.
Hydrogen Forward Scattering Spectrometry (HFS)In an HFS experiment a detector is placed 30° from the forward trajectory of the incident He++ ion beam and the sample is rotated so that the incident beam strikes the surfaces 75° from normal. In this geometry it is possible to collect light atoms, namely hydrogen, forward-scattered from a sample after collisions with the probing He++ ion beam. A thin absorber foil is placed over the detector to filter out He++ ions that are also forward scattered from the sample.
Hydrogen concentrations are determined by comparing the number of hydrogen counts obtained from reference samples after normalizing by the stopping powers of the different materials. A hydrogen implanted silicon sample and a geological sample, muscovite, are used as references. The hydrogen concentration in the hydrogen implanted silicon sample is taken to be its stated implant dose of 1.6×1017±0.2×1017 atoms/cm2. The muscovite (MUSC) sample is known to have ˜6.5±0.5 atomic percent hydrogen.
Samples are checked for hydrogen loss in the analyzed region. This is done by acquiring spectra for different acquisition times (initially a short exposure followed by a longer exposure to the He++ beam). Charge accumulations for 5 and 40 μC are used. A lower proportional signal in the 40 μC spectrum indicates hydrogen loss. In those cases the shorter exposure is chosen for analysis at the expense of higher noise in the spectrum. To account for surface hydrogen due to residual moisture or hydrocarbon adsorption a silicon control sample is analyzed together with the actual samples and the hydrogen signal from the control sample is subtracted from each of the spectra obtained from the actual samples. During the HFS acquisition backscattering spectra are acquired using the 160° angle detector (with the sample in forward scattering orientation). The RBS spectra are used to normalize the total charge delivered to the sample.
Analytical Parameters: HFSHe++ Ion Beam Energy 2.275 MeV
Normal Detector Angle 160°
Grazing Detector Angle ˜30°
Ion Beam to Sample Normal 75°
SEM ProcedureScanning electron microscope (SEM) Sample Preparation: Each syringe sample was cut in half along its length (to expose the interior surface). The top of the syringe (Luer end) was cut off to make the sample smaller.
The sample was mounted onto the sample holder with conductive graphite adhesive, then put into a Denton Desk IV SEM Sample Preparation System, and a thin (approximately 50 Å) thick gold coating was sputtered onto the interior surface of the syringe. The gold coating is required to eliminate charging of the surface during measurement.
The sample was removed from the sputter system and mounted onto the sample stage of a Jeol JSM 6390 SEM. The sample was pumped down to at least 1×10−6 Torr in the sample compartment. Once the sample reached the required vacuum level, the slit valve was opened and the sample was moved into the analysis station.
The sample was imaged at a coarse resolution first, and then higher magnification images were accumulated. The SEM images provided in the Figures are 5 μM edge-to-edge (horizontal and vertical).
AFM (Atomic Force Microscopy) ProcedureAFM images were collected using a NanoScope III Dimension 3000 machine (Digital Instruments, Santa Barbara, Calif., USA). The instrument was calibrated against a NIST traceable standard. Etched silicon scanning probe microscopy (SPM) tips were used. Image processing procedures involving auto-flattening, plane fitting or convolution were employed. One 10 μm×10 μm area was imaged. Roughness analyses were performed and were expressed in: (1) Root-Mean-Square Roughness, RMS; (2) Mean Roughness, Ra; and (3) Maximum Height (Peak-to-Valley), Rmax, all measured in nm. For the roughness analyses, each sample was imaged over the 10 μm×10 μm area, followed by three cross sections selected by the analyst to cut through features in the 10 μm×10 μm images. The vertical depth of the features was measured using the cross section tool. For each cross section, a Root-Mean-Square Roughness (RMS) in nanometers was reported. These RMS values along with the average of the three cross sections for each sample are listed in Table 5.
Additional analysis of the 10 μm×10 μm images was carried out. For this analysis three cross sections were extracted from each image. The locations of the cross sections were selected by the analyst to cut through features in the images. The vertical depth of the features was measured using the cross section tool.
The Digital Instruments Nanoscope III AFM/STM acquires and stores 3-dimensional representations of surfaces in a digital format. These surfaces can be analyzed in a variety of ways.
The Nanoscope III software can perform a roughness analysis of any AFM or STM image. The product of this analysis is a single color page reproducing the selected image in top view. To the upper right of the image is the “Image Statistics” box, which lists the calculated characteristics of the whole image minus any areas excluded by a stopband (a box with an X through it). Similar additional statistics can be calculated for a selected portion of the image and these are listed in the “Box Statistics” in the lower right portion of the page. What follows is a description and explanation of these statistics.
Image StatisticsZ Range (Rp): The difference between the highest and lowest points in the image. The value is not corrected for tilt in the plane of the image; therefore, plane fitting or flattening the data will change the value.
Mean: The average of all of the Z values in the imaged area. This value is not corrected for the tilt in the plane of the image; therefore, plane fitting or flattening the data will change this value.
RMS (Rq): This is the standard deviation of the Z values (or RMS roughness) in the image. It is calculated according to the formula:
Rq={Σ(Z1−Zavg)2/N}
where Zavg is the average Z value within the image; Z1 is the current value of Z; and N is the number of points in the image. This value is not corrected for tilt in the plane of the image; therefore, plane fitting or flattening the data will change this value.
Mean roughness (Ra): This is the mean value of the surface relative to the Center Plane and is calculated using the formula:
Ra=[1/(LxLy)]∫oLy∫oLx{f(x,y)}dxdy
where f(x,y) is the surface relative to the Center plane, and Lx and Ly are the dimensions of the surface.
Max height (Rmax): This is the difference in height between the highest and lowest points of the surface relative to the Mean Plane.
Surface area: (Optical calculation): This is the area of the 3-dimensional surface of the imaged area. It is calculated by taking the sum of the areas of the triangles formed by 3 adjacent data points throughout the image.
Surface area diff: (Optional calculation) This is the amount that the Surface area is in excess of the imaged area. It is expressed as a percentage and is calculated according to the formula:
Surface area diff=100[(Surface area/S12)−1]
where S1 is the length (and width) of the scanned area minus any areas excluded by stopbands.
Center Plane: A flat plane that is parallel to the Mean Plane. The volumes enclosed by the image surface above and below the center plane are equal.
Mean Plane: The image data has a minimum variance about this flat plane. It results from a first order least squares fit on the Z data.
Protocol for Lubricity TestingThe following materials is used in this test:
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- Commercial (BD Hypak® PRTC) glass prefillable syringes with Luer-Lok® tip) (ca 1 mL)
- COC syringe barrels made according to the Protocol for Forming COC Syringe barrel;
- Commercial plastic syringe plungers with elastomeric tips taken from Becton Dickinson Product No. 306507 (obtained as saline prefilled syringes);
- Normal saline solution (taken from the Becton-Dickinson Product No. 306507 prefilled syringes);
- Dillon Test Stand with an Advanced Force Gauge (Model AFG-50N)
- Syringe holder and drain jig (fabricated to fit the Dillon Test Stand)
The following procedure is used in this test.
The jig is installed on the Dillon Test Stand. The platform probe movement is adjusted to 6 in/min (2.5 mm/sec) and upper and lower stop locations were set. The stop locations were verified using an empty syringe and barrel. The commercial saline-filled syringes were labeled, the plungers were removed, and the saline solution is drained via the open ends of the syringe barrels for re-use. Extra plungers were obtained in the same manner for use with the COC and glass barrels.
Syringe plungers were inserted into the COC syringe barrels so that the second horizontal molding point of each plunger is even with the syringe barrel lip (about 10 mm from the tip end). Using another syringe and needle assembly, the test syringes were filled via the capillary end with 2-3 milliliters of saline solution, with the capillary end uppermost. The sides of the syringe were tapped to remove any large air bubbles at the plunger/fluid interface and along the walls, and any air bubbles were carefully pushed out of the syringe while maintaining the plunger in its vertical orientation.
The samples were created by coating COC syringe barrels according to the Protocol for Coating COC Syringe Barrel Interior with OMCTS Lubricity layer. An alternative embodiment of the technology herein, would apply the lubricity layer or coating over another thin film coating, such as SiOx, for example applied according to the Protocol for Coating COC Syringe barrel Interior with SiOx.
Instead of the Dillon Test Stand and drain jig, a Genesis Packaging Plunger Force Tester (Model SFT-01 Syringe Force Tester, manufactured by Genesis Machinery, Lionville, Pa.) can also be used following the manufacturer's instructions for measuring Fi and Fm. The parameters that are used on the Genesis tester are:
Start: 10 mmSpeed: 100 mm/min
Range: 20 Units: Newtons WORKING EXAMPLES Example 1 and Comparative Example AEmbodiment Example 1 versus comparative Example A shows a benefit in lubricity, in particular the break loose force (Fi), obtained by initially applying the lubricity coating or layer using high power in first phase of a PECVD process, and then reducing the power in a second phase. For this test, 1 mL syringes were used with FluroTec plungers. Multiple syringes were coated with a lubricity coating under the conditions set out in the table entitled, “20 Watts vs. 50 Watts Power.” The PECVD process was carried out in two phases, one following the other immediately, in the same equipment, without breaking vacuum between the two phases. In Phase 1, after allowing 15 seconds delay to allow the vacuum and gas flows to be established, PECVD was carried out at a power level of 20 Watts for one second in comparative Example A, and at a power level of 50 Watts for one second in Embodiment Example 1. In Phase 2, after a short additional delay both types of syringes were subjected to PECVD using the same gas mixture for similar times (the table noting a difference of 20 seconds of treatment for Example A vs. 15 seconds of treatment for Example 1).
Plungers were manually inserted in the syringes (although it has been found that manual insertion provides poorer results than automatic insertion, as discussed below). No plunger rods were used.
The treated syringes with plungers installed were then aged (put another way, the plungers were parked) for various periods of time up to a week, as indicated in the Table.
The lubricity performance (Fi, break loose force) of the respective samples was then tested, using a Genesis Packaging Plunger Force Tester (manufactured by Genesis Machinery, Lionville, Pa.). The equipment was used at a test speed of 300 mm/min.
As the Table, “20 Watts vs. 50 Watts Power,” shows, the syringes of Example A initially treated at 20 Watts had a consistently higher Fi, thus requiring more force to break the plunger loose, than the syringes of Embodiment Example 1.
Testing similar to that of Example 1 and Comparative Example A was carried out for Embodiment Examples 2 and 3 and Comparative Example B. This testing is summarized in the table entitled, Effect of Multi-Stage Process.” In these tests, however, different power profiles were tested. For Comparative Example B, the Phase 1 power was 20 Watts applied for one second. For Embodiment Example 2, the Phase 1 power was 50 Watts. For Embodiment Example 3, the Phase 1 power was a first pulse at 50 Watts for one second, followed by a delay of 3 seconds, a second pulse at 30 Watts for 1 second, followed by a delay of 3 seconds, and a third pulse at 15 Watts for one second. For all three examples, the Phase 2 treatment was similar, except for the change in OMCTS flow rate for Example 2. This information is summarized in the Table.
The Fi or break loose performance of the syringes was then tested essentially as described for Examples 1 and A, but with the following differences. The plungers used were Stelmi 6901 plungers. Standard plunger rods were used. The Genesis test speed was 100 mm/min.
The results are shown in the Table, “Effect of multi-stage process,” which shows that a Phase 1 power level of 50 Watts in Example 2 provided lower Fi, thus better performance, at all comparable park times, than the Phase 1 power level of 20 Watts used in Example B. The three-level power stepdown of Phase 1 in Example 3 provided still better performance at all comparable park times.
It is believed that this improvement occurs because the high-power first phase treatment conditions the thermoplastic substrate surface, allowing the subsequent second phase treatment at low power to
Examples 4 and 5 and Comparative Examples C-ETesting similar to that of Example 1 and Comparative Example A was carried out for Embodiment Examples 4 and 5 and Comparative Examples C, D, and E. In these tests, however, after the syringes were coated and before they were tested for lubricity they were heated in an oven for 24 hours at 100° C. at a pressure of 1 Torr (gauge). This testing is summarized in the table entitled, “Oven Treatment.”
As the Oven Treatment table shows, this treatment reduced and thus improved the break loose force, both initially (0 days) and after aging the lubricated syringes for 7 days.
Without limiting the invention according to the accuracy of this theory, it is believed that this improvement with oven treatment under vacuum occurs because the treatment drives more volatile constituents in the coating away, leaving a more durable baked on lubricity coating or layer. It is postulated that the improvement is due to driving off low molecular weight species from the lubricity layer, which would help limit the amount of molecular entanglements formed during aging. An increase in molecular entanglements over time is one potential mechanism associated with the break loose force aging phenomena.
Example 6While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art and practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.
Claims
1. A method for preparing a lubricity coating on a plastic substrate, in which the substrate is a syringe, the method comprising:
- (a) providing a gas comprising: i. an organosilicon precursor, ii. optionally an oxidizing gas, and iii. a diluent gas in the vicinity of the substrate surface; and
- (b) generating plasma in the gas by providing plasma-forming energy adjacent to the plastic substrate, thus forming a coating on the substrate surface by plasma enhanced chemical vapor deposition (PECVD);
- in which:
- the plasma-forming energy is applied in a first phase as a first pulse at a first energy level followed by further treatment in a second phase, at a second energy level lower than the first energy level, and reduces the breakout force, Fi, of the syringe, compared to the breakout force of a similar syringe that has only been treated at the second energy level;
- the resulting lubricity coating has an atomic ratio SixOxCyHz or Siw(NH)xCyHz wherein w is 1 as measured by X-ray photoelectron spectroscopy (XPS), x is from about 0.5 to about 2.4 as measured by XPS, y is from about 0.6 to about 3 as measured by XPS, and z is from 2 to about 9 as measured by Rutherford backscattering spectrometry (RBS); and
- the lubricity coating has a lower frictional resistance than the uncoated surface.
2. The method of claim 1, in which the first pulse energy level is from 21 to 100 Watts.
3. The method of claim 1, in which the first pulse is applied for 0.1 to 5 seconds.
4. The method of claim 1, in which a second pulse is provided at a lower energy level than the first pulse.
5. The method of claim 1, in which the second phase energy level is from 1 to 10 Watts.
6. The method of claim 1, in which the syringe size is from 1 to 10 mL.
7. The method of claim 1, in which the lubricity coated syringe is further treated by post heating it, optionally at 50 to 110 degrees C. for a time interval of 1 to 72 hours.
8. The method of claim 7, in which the post heating step is carried out under at least partial vacuum, alternatively under a pressure of less than 50 Torr.
9. The method of claim 1, wherein the organosilicon precursor comprises a linear or monocyclic siloxane.
10. The method according to claim 1, wherein O2 is present in a volume-volume ratio to the organosilicon precursor of from 0:1 to 2:1.
11. The method according to claim 1, wherein Ar is present as the diluent gas.
12. The method according to claim 1, wherein the gas comprises from 1 to 6 standard volumes of the organosilicon precursor, from 1 to 100 standard volumes of the diluent gas, and from 0.1 to 2 standard volumes of O2.
13. The method according to claim 1, wherein both Ar and O2 are present.
14. (canceled)
15. The method according to claim 1, additionally comprising a step for preparing a barrier coating on the substrate before the lubricity coating is applied, the additional step comprising:
- (a) providing a gas comprising an organosilicon precursor and an oxidizing gas in the vicinity of the substrate surface; and
- (b) generating plasma from the gas, thus forming an SiOx barrier coating, in which x is from 1.5 to 2.9 as measured by XPS, on the substrate surface by plasma enhanced chemical vapor deposition (PECVD).
16. The method according to claim 15 wherein in the step for preparing a barrier coating
- (i) the plasma is generated with electrodes powered with sufficient power to form the SiOx barrier coating on the substrate surface
- (ii) the ratio of the electrode power to the plasma volume is equal or more than 5 W/ml;
- (iii) the O2 is present in a volume:volume ratio of from 1:1 to 100:1 in relation to the silicon containing precursor.
17. The method according to claim 1, wherein the substrate is a polymer selected from the group consisting of a polycarbonate, an olefin polymer, a cyclic olefin copolymer (COC), a cyclic olefin polymer (COP), and a polyester.
18. The method according to claim 1, wherein the plasma is generated with microwave energy, RF energy, or a combination of the two.
19. (canceled)
20. A method for preparing a lubricity coating on a plastic substrate of a syringe, the syringe comprising a barrel having an inner surface and a piston or plunger having an outer surface engaging the inner surface of the barrel, wherein at least one of said inner surface and outer surface is the coated substrate, the method comprising:
- (a) providing a gas comprising: i. an organosilicon precursor, ii. optionally an oxidizing gas, and iii. a diluent gas
- in the vicinity of the substrate surface; and
- (b) generating plasma in the gas by providing plasma-forming energy adjacent to the plastic substrate, thus forming a coating on the substrate surface by plasma enhanced chemical vapor deposition (PECVD);
- in which the plasma-forming energy is applied in a first phase as a first pulse at a first energy level followed by further treatment in a second phase, at a second energy level lower than the first energy level, and reduces the breakout force, Fi, of the syringe, compared to the breakout force of a similar syringe that has only been treated at the second energy level;
- wherein the resulting lubricity coating has an atomic ratio SiwOxCyHz or Siw(NH)xCyHz, wherein w is 1 as measured by X-ray photoelectron spectroscopy (XPS), x is from about 0.5 to about 2.4 as measured by XPS, y is from about 0.6 to about 3 as measured by XPS, and z is also from 2 to about 9 as measured by hydrogen forward scattering (HFS).
21.-30. (canceled)
31. A vessel processing system for coating of a vessel, the system comprising a processing station arrangement configured for performing the method of claim 1.
32. (canceled)
33. (canceled)
Type: Application
Filed: Mar 14, 2014
Publication Date: Jan 21, 2016
Inventors: Joseph A. Jones (Birmingham, AL), John T. Felts (Alameda, CA), James Troy Gresham (Opelika, AL), Brian Russell Lilly (Auburn, AL), Thomas E. Fisk (Green Valley, AZ)
Application Number: 14/774,742
