Glass container and method for manufacturing the same

Abstract

This invention relates to a glass container, particularly a glass container for containing a formulation, the container comprising a hollow body having an internal volume, particularly for containing the formulation, wherein the hollow body includes a wall having an inner surface and an outer surface opposite to the inner surface, the inner surface defining the internal volume of the hollow body, wherein the wall includes, at least in a partial region, a region of compressive stress, wherein the formed region of compressive stress is adjacent to the outer surface so that the outer surface is compressively prestressed at least in a partial region, and wherein the inner surface of the wall opposite to the partial region is not under compressive stress and is preferably under tensile stress; the invention also relates to a method for chemically prestressing the glass container, particularly a method for chemically prestressing a glass container for containing a formulation.

Description

[0001] This invention is a divisional application of Chinese Patent Application No. 201911071359.7, entitled "Glass Container and Method of Manufacturing Thereof," filed on November 5, 2019. Technical Field

[0002] The present invention generally relates to a glass container and a method for manufacturing the same, particularly a glass container with specific strength, which is preferably used to contain preparations, especially cosmetic, medical or pharmaceutical preparations. Background Technology

[0003] Glass containers, or so-called primary glass packaging, used to contain cosmetic, medical, or pharmaceutical preparations are well-known and can be manufactured in various geometries and quality grades. These containers are suitable for storing, transporting, or even administering preparations. They can be mass-produced at low cost as cartridges, vials, or ampoules, for example.

[0004] Such containers can be made not only of glass, but also of materials such as plastic. However, because glass is chemically inert, glass containers have advantages, for example, in terms of the lifespan of the packaging or the potential contamination of the formulation contained therein.

[0005] Typically, the glass containers are cleaned before filling, sealing, and then transporting or packaging them into larger containers. This is done using suitable equipment, which is usually fully automated.

[0006] During this process, the containers must withstand specific strains. On the one hand, during transportation, containers may come into contact with or collide with each other, potentially experiencing significant radial or axial forces. This can lead to surface damage, such as scratches on the outer surface of the container, or even cracks. Sometimes, significant forces or impacts can also affect the extent of container breakage, especially if the container is made of glass. This is a major issue, particularly in the case of primary pharmaceutical packaging, especially when adhering to cleanliness requirements.

[0007] Another relevant factor for drug containers may be internal pressure, which can affect the container during the filling process with, for example, liquid formulations. In adverse conditions, excessive pressure during filling or lyophilization can cause the container to explode. This problem can be further exacerbated if the container has already suffered prior damage, for example, due to the aforementioned forces.

[0008] Application document WO 2013 / 130721 A1 proposes a solution. It discloses an aluminosilicate glass container having at least one prestressed sidewall. Applying prestress to the sidewall should ensure that if a crack forms that penetrates the sidewall and could compromise the sterility of the container's interior, the container is severely damaged to the point of being unusable for its intended purpose. Therefore, it is disclosed to introduce tensile stress into the sidewall, particularly into the central region of the sidewall, at a tensile stress exceeding a threshold of 15 MPa, and exemplary embodiments are described only for containers with compression prestressing both externally and internally.

[0009] This prestressing through mutual compression can be achieved through ion exchange in the near-surface layer of the glass during a heated brine bath. In some types of glass, this process involves exchanging smaller ions (e.g., sodium ions) present in the near-surface layer of the glass for larger ions (e.g., potassium ions) in the brine bath. This generates compressive stress in the surface region, thereby increasing the glass's strength.

[0010] However, during this process, the inner surface of the glass container (i.e., the surface that subsequently comes into contact with the filling formulation) also undergoes this ion exchange and, consequently, a chemical change. For some formulations, this can be detrimental, meaning that the possible uses of such glass containers are limited. Therefore, types of glass typically permitted for medical use also undergo significant alterations, at least on their inner surfaces, leading to the invalidation or re-approval of these glass types for medical applications.

[0011] Other methods are also known, in which further processing, particularly cleaning or de-alkali removal, is carried out downstream of the chemical prestressing process. Admittedly, this post-treatment may reduce the release of alkali into the drug, but such cleaning / de-alkali removal leads to further chemical modification of the glass surface, thus necessitating re-approval of the appropriate glass container as a primary packaging method for the drug. Furthermore, only a shallow depth can be achieved to further remove the material introduced via the saline bath. Summary of the Invention

[0012] Therefore, the object of the present invention is to provide a drug container that has higher strength relative to radial or axial forces from external impact compared to a standard unstressed container, and that the drug container also has higher or at least equal internal compressive strength relative to a standard unstressed container, and that the drug container does not require a re-approval process for the drug.

[0013] The features of the independent claims fulfill this objective. Favorable embodiments and improvements can also be derived from the dependent claims and the specification.

[0014] This invention discloses a glass container, particularly a glass container for containing a preparation, comprising a hollow body having an internal volume, particularly a hollow body for containing a preparation, wherein the hollow body includes a wall having an inner surface and an outer surface opposite to the inner surface, the inner surface defining the internal volume of the hollow body, wherein the wall includes, at least in a partial region, a region of compressive stress, wherein the region of compressive stress is formed in the wall defining the outer surface, such that the outer surface is compressively prestressed at least in a partial region, and wherein the inner surface of the wall opposite to the partial region is not under compressive stress, and is preferably under tensile stress.

[0015] The present invention further includes a method for chemically prestressing a glass container, particularly a glass container for containing a formulation, wherein a hollow body defines an internal volume, particularly for containing the formulation, and the hollow body includes a wall having an inner surface and an outer surface opposite to the inner surface, the inner surface pointing towards the internal volume of the hollow body, the hollow body being immersed, starting from the bottom or opening, in a brine bath containing potassium nitrate (KNO3) to a predetermined depth, preferably at a high temperature of at least 400°C but below the Tg of the glass, for a duration of 1 to 24 hours, preferably 1 to 8 hours, thereby generating compressive stress at least locally on the outer surface, such that the outer wall is at least partially compressively prestressed.

[0016] For the purposes of this invention, the container is considered a vessel or receiver suitable for containing gaseous, solid, or liquid materials, or mixtures of gaseous, solid, and / or liquid materials. The internal volume of the hollow body of the container may be filled, for example, with cosmetic, medical, or pharmaceutical preparations, preferably in liquid form, but also in solid form or mixtures thereof. Such a container may be, for example, a vial, ampoule, syringe, or cartridge.

[0017] For this purpose, the hollow body can have a wall having an inner surface and an outer surface arranged opposite to the inner surface, the inner surface pointing towards the internal volume of the hollow body and the outer surface pointing towards the external environment. The hollow body can be a generally rotationally symmetrical shape with an upper and lower end, wherein the cylindrical region can consist of a raw tube from which a container is formed by thermoforming, and the cylindrical region can preferably include an opening for filling or emptying the hollow body. This opening can be arranged at the upper end.

[0018] In a preferred embodiment, such as in the case of a vial, the wall of the hollow body may include sidewalls and a bottom, as well as a rounded-off edge formed between the bottom and the sidewalls, which represents a transition area between the sidewalls and the bottom; hereinafter, this rounded-off edge is also referred to as the heel. The bottom here forms the lower end of the hollow body. For a vial, a shoulder adjacent to the sidewalls may be provided in the direction of the lower end, which may transition to a neck and include an upper terminal. The neck and terminal preferably include channels representing openings to the internal volume of the hollow body. The upper terminal (particularly in the case of primary packaging such as cartridges or vials) is also called a rolled edge and is arranged opposite the bottom.

[0019] For the purposes of this description, the terms "top" or "bottom" are used relative to the container, meaning the upper and lower ends of the hollow body or container as can be understood from the accompanying drawings. In this context, the term "inner" refers to a region or surface of the hollow body or container that can be considered to point towards the internal volume of the hollow body, and the term "outer" refers to those regions or surfaces of the hollow body or container that point towards the external environment. For the purposes of this disclosure, the term "radial" is used to refer to a cylindrically symmetrical container, which is not explicitly defined. If the container has a non-cylindrical symmetrical shape or deviates from a cylindrical symmetrical shape, the term "radial" defines a direction extending perpendicularly from the outer surface of the container to the inner surface of the container. The expression "within a region deviating 0.5 μm from the outer surface to a region deviating 0.5 μm from the inner surface" refers to the region of a straight line extending radially from the outer surface to the inner surface. For the purposes of this disclosure, reference is made to the center of the wall, which represents the center between the outer and inner surfaces along the aforementioned straight line.

[0020] Such glass containers can be manufactured, for example, by drawing the portions of a glass tube and then thermoforming them. A glass composition suitable for primary pharmaceutical packaging can be selected, preferably borosilicate glass or aluminosilicate glass.

[0021] According to the invention, the outer surface of the wall may include an externally arranged layer or region with compressive stress, such that the outer wall is at least partially compressively prestressed. In other words, the wall of the container may at least partially include unilateral external compressive prestressing. This means that the wall includes at least one layer or region on its outer surface that extends into the wall to a certain depth and has compressive stress different from the stress in the rest of the wall, particularly the inner surface of the wall opposite the outer surface.

[0022] Therefore, preferably, the compressive stress on the outer surface of the hollow body's wall is higher than the stress on the opposite inner surface of the wall. Particularly preferably, tensile stress resisting the compressive stress exists on the inner surface of the wall opposite the compressive prestressing on the outside. Thus, a container comprising a hollow body with a wall prestressed on the outside (i.e., on one side) can be obtained.

[0023] This compressive prestressing, also known as prestressing, can be achieved through thermal or preferably chemical means.

[0024] Hot prestressing of containers, starting with a glass thickness of approximately 3 mm, can be advantageously employed. In this process, the glass is first continuously heated in an oven to a temperature exceeding 600°C, and then rapidly cooled by blowing cold air onto it. Due to this defined process, a compressive stress zone is formed on the glass surface, surrounding a tensile stress zone present in the glass core. Because of this defined stress ratio, the mechanical and thermal strength of hot-prestressed glass is 3 to 4 times higher than that of unprestressed glass. Since the wall thickness of glass containers used, particularly in the pharmaceutical field, is typically less than 3 mm, the prestressing method of the present invention is less suitable for them, especially for glass containers with a wall thickness less than 3 mm.

[0025] In contrast, chemical prestressing is different; there is virtually no such limitation on the width of the walls (i.e., the thickness of the glass walls to be chemically prestressed). Chemical compressive stressing of the vessel can be achieved by subjecting it to an elevated temperature of approximately 400°C or higher and immersing it in a brine bath containing potassium nitrate (KNO3). However, in this case, the temperature should be kept below the glass's Tg to prevent any significant relaxation, allowing stress to be formed in a defined manner, but high enough to allow for sufficiently rapid and deep ion exchange at the surface.

[0026] The chemical hardening process can also be carried out sequentially in these different brine baths, wherein the process of introducing the brine bath lasts approximately 1 to 24 hours, preferably 1 to 8 hours.

[0027] Using this chemical prestressing method, smaller sodium ions from the near-surface layer of the glass are exchanged for larger potassium ions from the brine bath. The larger potassium ions are introduced into the glass network, resulting in the formation of a near-surface layer or region with compressive stress. The surface treated accordingly in this paper undergoes potassium ion enrichment and sodium ion depletion, resulting in a surface containing a higher potassium ion content than the original glass. The maximum compressive stress CS can occur on the surface itself or beneath the compressively prestressed surface.

[0028] The depth or thickness of the prestressed layer on the outer surface of the wall is often referred to as DOL (layer depth). This thickness DOL can be determined by means of a photo-elastic zero passage measurement method, such as using a measuring device with the trade name FSM-6000.

[0029] This measuring device can also be used to determine the compressive stress on the surface and the maximum compressive stress CS of the panel. Typically, the thickness DOL of the prestressed layer approximately corresponds to the depth to which larger ions penetrate from the brine bath into the glass surface.

[0030] With regard to the term "alkali metal" as used below, it should be specifically understood to refer to the elements potassium and sodium or their ions in glass, wherein, when mentioned below, the conversion values ​​of oxides are disclosed respectively.

[0031] Inside the glass, starting from the outer surface, tensile stress is generated in a direction perpendicular to the surface through prestressing, opposite to the compressive stress direction. This tensile stress begins at the aforementioned depth DOL adjacent to the compressive stress region. In glass prestressed on both sides, this is particularly applied to the central region of the wall, such that the central wall region with tensile stress is surrounded on both sides by regions with increased compressive stress at corresponding depths DOL, as described, for example, in WO 2013 / 130721 A1. In that publication, CT represents the tensile stress value in the central wall region, where the tensile stress is also highest when prestressing is performed on both sides. Then, according to the invention, using unilateral external prestressing, the tensile stress CT extends all the way to the inner surface of the wall, where in this disclosure it is denoted by IST, and CT does not necessarily represent the maximum value of the tensile stress. Therefore, for glass prestressed on both sides, the outer surface of the wall is under increased compressive stress, while in the central region of the wall, tensile stress acting in the opposite direction dominates.

[0032] According to the invention, prestressing is provided only to the outer surface of the wall, at least partially, rather than to the inner surface of the wall.

[0033] Surprisingly and unexpectedly, the strength of glass containers that are compressed and prestressed on only one side (on the outside) is significantly improved, especially when subjected to external impacts under certain forces, and when the containers are subjected to loads, for example, during filling and transportation.

[0034] This includes increased strength during filling and / or sealing, which is problematic, especially in the case of brittle, hard materials such as glass, but provides good strength against axial or radial impact forces (lateral compression) or impacts, as is the case in automated transport processes, for example.

[0035] Since it must be assumed that the tensile stress caused by unilateral external compression prestressing will affect the hollow body wall under the above-mentioned load conditions of the vessel, resulting in a decrease rather than an increase in the expected final strength, it is not currently expected to improve the strength of the vessel through unilateral prestressing.

[0036] What is now completely unexpected is that, apparently, for externally compressed prestressed glass containers, the bursting pressure remains essentially unchanged, and in particular, the strength of the container can be significantly increased by external forces resisting impact, such as axial and radial compression or impact.

[0037] To understand this unexpected material behavior of glass containers with external unilateral prestressing, structural mechanics modeling with corresponding simulations was performed to better understand the stress modes resulting from this unilateral prestressing. The study shows that, in this case, i.e., for externally prestressed containers, the tensile stress CT, typically present in the central region of the glass, extends all the way to the inner surface of the hollow body wall, where it is also referred to as internal surface tension, or simply IST.

[0038] Therefore, based on the generally known rules for estimating the tensile stress CT in prestressed glass on both sides, it is no longer possible to estimate the level of this tensile stress IST, i.e.:

[0039] CT = (CS x DOL) / (t - 2DOL).

[0040] Here, t represents the wall thickness, and it is assumed that the tensile equilibrium based on the ratio between the central tensile stress region CT x (t-2DOL) and the two adjacent external compressive stress regions 2 x 1 / 2 (CS x DOL) can be derived from the product of the extension depth of each increased stress and the increased stress, respectively. Therefore, in order for the external compressive stress to be equal to or in equilibrium with the internal tensile stress, the following condition applies:

[0041] CT x(t-2DOL)=2x1 / 2(CS x DOL).

[0042] In contrast, the tensile stress IST (internal surface tension) on the inner surface according to the invention is derived from the tensile balance between a single tensile stress region and only a single compressive stress region. Therefore, for the equilibrium state, it is assumed that the introduced stress has been balanced, and the following approximation applies:

[0043] ISTx(t-DOL)=1 / 2(CSxDOL).

[0044] Therefore, the following applies to innovative tension distribution in the walls of hollow containers:

[0045] IST=0.5x(CS x DOL) / (t-DOL),

[0046] Wherein CS describes the maximum compressive stress introduced in a region of the outer surface, which is generated by compressive stress zones respectively located near or adjacent to the outer surface.

[0047] DOL describes the depth of this compressive stress zone, starting from the outer surface.

[0048] t describes the thickness of the wall, on which a compressive stress zone is introduced.

[0049] By utilizing the unilateral external prestressing according to the invention, the tensile stress CT now extends all the way to the inner surface of the wall, which is referred to as IST in this disclosure.

[0050] Given this tension pattern within the container wall, the inventors were able to achieve a very favorable balance between increasing the strength of the container and preventing degradation (e.g., degradation of the compressive strength inside the container, and thus degradation of the container's performance related to burst pressure).

[0051] For example, in the case of unilateral prestressing, excessive tensile stress may lead to a decrease in container strength under load conditions associated with very high tensile stress loads on the inner surface. However, on the other hand, higher strength can be achieved relative to external impact forces, such as axial or radial impacts, or impacts from the outside onto the glass container.

[0052] Even if the burst pressure (i.e. the magnitude of the tensile stress that can be maximally withstood on the inner surface) cannot be increased, the strength relative to axial and radial forces will still affect the performance of the vessel.

[0053] To verify the results obtained through structural mechanics modeling, strength tests were conducted on the glass containers. For this purpose, containers of borosilicate glass and aluminosilicate glass with uniform geometry were tested separately, with each container having a nominal volume of 2 ml (2R vials) in the example, forming test batches of 50 containers each.

[0054] Tests were conducted by applying unilateral chemical external prestressing to a 1 mm thick container in a tubular or cylindrical region of the sidewall. In the case of borosilicate glass, the resulting compressive prestressed surface layer exhibited a compressive prestress of approximately CS = 200 MPa, with a prestressing depth (DOL) of approximately 35 μm. In the case of aluminosilicate glass, the resulting compressive prestressed surface layer exhibited a compressive prestress of approximately CS = 800 MPa, with a prestressing depth of approximately DOL = 55 μm. Comparisons were made using samples of the same material and geometry that had not been prestressed.

[0055] To determine the so-called burst pressure, a burst test is used to determine the strength during filling. This burst test is a destructive test used to determine the burst pressure of a hollow body. It is used to determine the maximum sustained tensile stress.

[0056] The samples were subjected to burst pressure tests, axial and diametrical or radial compression impacts, and pendulum impact tests to examine their performance under impact conditions.

[0057] These tests demonstrate that, in the case of borosilicate glass containers with unilateral external prestressing, the bursting pressure remains virtually unchanged, while in the case of aluminosilicate glass containers with unilateral external prestressing, the bursting pressure is significantly reduced.

[0058] Significant improvements in strength were observed in all other three tests: axial compression and diametrical or radial compression impacts on the container, and pendulum impact tests.

[0059] Under axial and radial or diametrical compression, containers comprising aluminosilicate glass with unilateral external prestressing exhibit increased strength relative to an equivalent unstressed container, the strength of which is equivalent to that of a container with unilateral external prestressing of borosilicate glass.

[0060] In contrast, in the case of borosilicate glass containers, compared to the three load conditions mentioned last, less compressive prestressing on the surface is sufficient to achieve a significant increase in strength without causing a decrease in burst pressure. Therefore, the present invention is particularly suitable for containers comprising or made of borosilicate glass.

[0061] Therefore, the generation of tensile stress on the inner surface of the wall is a fundamental characteristic of the container's strength, especially in the case of external impact or axial or radial impact forces, where its magnitude has a crucial influence on strength. According to the invention, care must be taken to ensure an optimal value for the tensile stress; exceeding this value leads to weakening of the inner surface of the wall, while failing to reach it results in insufficient improvement in the strength of the outer surface of the hollow body wall.

[0062] In summary, the unilateral external prestressing of the glass container according to the invention has the effect that the inner surface of the container, i.e., the surface of the wall pointing towards the internal volume and thus able to contact the filled formulation, has no compressive prestressing layer. Conversely, tensile stress, which dominates in the direction opposite to compressive stress and typically in the center of the bidirectionally prestressed glass plate, can extend beyond the center of the wall of the container according to the invention to the inner surface of the wall. Therefore, it is preferable to have (small) tensile stress on the inner surface of the wall.

[0063] In other words, an asymmetrical profile of prestressed mode is formed within the wall, where the outer half of the wall includes (positive) compressive stress on average, and the inner half of the wall includes (negative) tensile stress on average. However, the internal tensile stress is significantly less than the external compressive stress.

[0064] In a preferred embodiment, and based on this stress mode of the wall, a glass container can be provided having a hollow body with relatively high compressive prestress on its outer surface, compared to very low tensile stress on its center and inner surface, wherein:

[0065] IST<0.8*(CS x DOL) / (t—2DOL),

[0066] and / or

[0067] 0.3*(CS x DOL) / (t—DOL) <IST<0.7*(CS x DOL) / (t—DOL)。

[0068] In another preferred embodiment, a glass container may be provided in which the tensile force on the inner surface of the wall IST (preferably the region opposite the region on the outer surface with compressive prestressing) is preferably IST >= 0 MPa and IST <= 30 MPa, preferably IST <= 20 MPa, particularly preferably IST <= 15 MPa, and most particularly preferably IST <= 5 MPa. This ensures that the tensile stress caused by prestressing does not increase too much, thereby preventing the container's rupture behavior from deteriorating significantly or preferably not at all; that is, it preferably maintains rupture resistance.

[0069] From the center of the wall of the container of the present invention to the inner surface of the wall, the tensile stress pattern can be relatively constant, that is, the level of tensile stress at the center of the wall is approximately equal to the level of tensile stress on the inner surface of the wall in the region. In a preferred embodiment, the level of tensile stress from the center of the wall to the inner surface of the wall is subject to only small fluctuations, preferably within + / -10%, more preferably within + / -5%.

[0070] Therefore, the container according to the invention is further characterized in that only one side of the wall, preferably only the outer surface of the wall, includes a near-surface compression prestressed zone with a thickness of not more than 15%, preferably not more than 10%, particularly preferably not more than 8% relative to the wall thickness.

[0071] In the most particularly preferred embodiment, the thickness of the near-surface compressive prestressed zone on the outer surface of the wall is no more than 6% relative to the wall thickness. Therefore, for a wall thickness of, for example, t = 1.6 mm, the thickness of the near-surface compressive prestressed zone is approximately DOL = 96 μm. As a result, it is possible, with high reliability, particularly under chemical prestressing, to achieve a potassium-rich region on the outer surface where the composition changes due to prestressing.

[0072] Therefore, the central region of the wall and the inner region extending from the center of the wall to the inner surface of the wall are preferably free of additional alkali metals, preferably potassium ions, introduced by prestressing. Generally, in the region 0.5 μm from the outer surface up to 0.5 μm from the inner surface, the distribution of alkali metals introduced by prestressing monotonically decreases from the outer surface of the wall to the inner surface. Because alkali metals in the innermost thin layer can be removed again by processes such as leaching (e.g., using ABF (ammonium bifluoride)), this region extends to a depth of, for example, 100 μm or even only 10 μm.

[0073] Therefore, on the inner surface of the wall, the amount of K2O and Na2O, on average up to a depth of 500 μm, is preferably no more than 10% by weight, particularly no more than 9%, and especially preferably no more than 8%. According to the invention, this amount is measured at a moderate height on the inner surface of the wall as observed from the bottom.

[0074] In summary, after chemical prestressing, the concentration distribution of the alkali metals exchanged during chemical prestressing is dominant. This distribution starts with a high value near the outer surface of the wall and decreases to a lower intrinsic value near or at the inner surface of the glass, which is essentially zero or equal to zero.

[0075] Therefore, a major advantage of the present invention is that the chemical properties of the inner surface of the container that interacts with the drug remain unchanged. This is particularly advantageous for containers intended to contain cosmetic, medical, or pharmaceutical preparations. Simultaneously, the strength of the container according to the invention can be increased, thereby significantly improving the product reliability of the container, especially during transportation and / or filling. Similarly, when a container is sealed, for example, with a closure such as a stopper, high internal pressures are generated, which can lead to rupture. Here, the reliability of the container according to the invention is also improved.

[0076] This advantage is particularly pronounced for borosilicate glass containers, as this type of glass achieves the required chemical stability without requiring chemical pretreatment. However, if the inner surface of the hollow body walls is also chemically prestressed—that is, a high concentration of alkali metals, specifically potassium ions from a brine bath, are introduced to replace sodium ions in the glass—this typically occurs at a depth of tens of micrometers from the inner surface. While it is possible to remove small amounts of these alkali metals again through chemical post-treatment, this requires additional processing steps and is only successful in the outermost surface layer. Furthermore, the amount of alkali metals released from the inner surface after post-treatment depends, of course, largely on the intensity of the post-treatment, parameters such as duration, temperature, and pH, but may also depend on factors such as the geometry of the container. Therefore, chemically prestressed and post-treated inner surfaces cannot be presumed to be chemically invariant glass surfaces as they are to unprestressed glass surfaces.

[0077] According to the invention, on the one hand, chemical post-treatment of the inner surface can be advantageously eliminated, and on the other hand, the inner surface of the container wall, even to a greater depth that can be measured from the inner surface of the wall, is substantially free of alkali introduced by chemical prestressing.

[0078] This provides a high-strength primary pharmaceutical packaging made of glass, preferably aluminosilicate or borosilicate glass, wherein the inner surface of the container wall is in contact with, for example, the formulation of the drug, measured from a depth perpendicular to the wall, at a maximum of 100 μm, preferably at a maximum of 150 μm, and particularly preferably at a maximum of 200 μm, and its alkali metal concentration is not affected by chemical prestressing of the glass (e.g., a block of glass in the center of the container wall). Therefore, it is generally preferable that the concentration of potassium ions in this region does not increase relative to the block glass.

[0079] Furthermore, according to the present invention, a borosilicate glass primary pharmaceutical package with enhanced strength can be provided, wherein the chemical properties of the inner surface of the container wall in contact with the formulation, such as a drug, are unchanged compared to the surface of a container that has not been pre-stressed. Therefore, the formulation, such as a drug, as described above, only contacts the original borosilicate glass surface.

[0080] According to the invention, the strength of a glass container, preferably where the critical load primarily occurs, is improved by unilateral external prestressing. Typically, this refers to a surface region on the outer surface of the wall, preferably in the region of the sidewall. Furthermore, it also seems convenient to prestress the bottom or at least the heel on the outer side, where, empirically, the maximum load occurs. This may also include internal thickening of the glass in this region to mitigate or even avoid potential increases in tensile stress that may arise from compressive stress zones in the heel region.

[0081] In an improved embodiment of the invention, additional areas of the outer wall of the container are also externally prestressed on one side, for example, those areas of the outer wall adjacent to the sidewall of the hollow body. When the container is a vial, these areas may be the shoulder and / or neck and / or edging of the hollow body.

[0082] Advantageously, a container comprising or made of glass, particularly for containing formulations, is further disclosed. This container includes a hollow body having an internal volume, specifically for containing the formulation. The hollow body includes a wall having an inner surface and an outer surface opposite the inner surface, the inner surface defining the internal volume of the hollow body. The wall includes, at least in a partial region, a region of compressive stress, formed in the wall defining the outer surface. At the center of the wall, i.e., at the center between the outer and inner surfaces, the tensile stress CT is expressed as CT >= 0 MPa and CT <= 20 MPa, preferably CT <= 15 MPa, particularly preferably CT <= 5 MPa. This design is used to safely avoid the rupture behavior described in WO2013 / 130721A1.

[0083] Advantageously, the walls of the hollow body form at least one opening, and / or a rolled edge and / or a neck and / or a shoulder and / or a side wall and / or a heel and / or a bottom.

[0084] When a region or area containing compressive stress is formed, adjacent to or adjacent to the shoulder, neck, rim, sidewall, heel and / or bottom, it is advantageous to adapt the strength characteristics of the vessel to the corresponding requirements regarding its mechanical loads.

[0085] Because the region of compressive stress is formed on the wall adjacent to the outer surface, compressive stress is formed in the region of the outer surface, particularly to depth DOL, and there is an asymmetrical profile of the stress mode from the outer surface of the wall to the opposite inner surface in the radial direction about the center of the wall. Substantial advantages can be obtained with respect to symmetrical prestressing, such as a significant increase in strength without having to accept the substantial disadvantages mentioned here regarding resistance to bursting pressure.

[0086] Advantageously, it can be said here that in the region of compressive stress in the outer surface, the tension IST (internal surface tension) is formed as tensile stress on the inner surface of the wall opposite to that region, and the tensile stress IST is expressed as follows: IST>=0MPa and IST<=30MPa, preferably IST<=20MPa, particularly preferably IST<=15MPa, and most particularly preferably IST<=5MPa.

[0087] In a particularly preferred embodiment, in the region where the outer surface has compressive stress, the tension, particularly the tensile stress on the opposite inner surface of the wall, is expressed as:

[0088] 0.3*(CS x DOL) / (t—DOL) <IST<0.7*(CS x DOL) / (t—DOL),

[0089] Where DOL represents the depth of the region where compressive stress exists.

[0090] t represents the thickness of the wall, and

[0091] CS stands for stress, specifically compressive stress on the outer surface.

[0092] The inventors discovered that in regions with compressive stress on the outer surface, the level of tensile stress at the center of the wall is approximately equal to the level of tensile stress on the opposite inner surface of the wall. Preferably, the level of tensile stress from the center of the wall to the inner surface of the wall experiences only minor fluctuations, within + / -10%, more preferably within + / -5%. This provides consistent stress, particularly tensile stress, over a large area of ​​the vessel wall, avoiding tension spikes and the associated reduction in burst pressure.

[0093] Advantageously, for regions with compressive stress in the outer surface, the near-surface compressive prestressed zone has a thickness or depth DOL that is no more than 15%, preferably no more than 10%, particularly preferably no more than 8%, and most particularly preferably no more than 6% of the wall thickness or width in that region.

[0094] Preferably, during chemical prestressing in regions with compressive stress, at least in regions 0.5 μm from the outer surface to 0.5 μm from the inner surface, after chemical prestressing from the outer surface of the wall toward the opposing inner surface, the distribution of alkali metals introduced into the glass during chemical prestressing directly and monotonically decreases.

[0095] In this case, at least in the compressive stress-treated area of ​​the outer surface, the glass at a depth of at most 100 μm, preferably at most 150 μm, and particularly preferably at most 200 μm on the opposite inner surface of the wall, relative to the glass at the center of the wall, does not contain a certain concentration of additionally introduced alkali metal substances so that the chemical prestressing does not adversely affect the use of the container in medical applications.

[0096] In a preferred embodiment, at least on the inner surface of the wall opposite the compressive stress region, the average content of K2O and Na2O up to a depth of 500 μm is not greater than 13% by weight, preferably not greater than 9%, and particularly preferably not greater than 8%.

[0097] Various embodiments are applicable to this method depending on the amount of prestressing provided. If, for example, only the bottom and / or heel and / or sidewalls are chemically prestressed on one side, then obviously the container should be immersed in the brine bath starting from the bottom. If the adjacent area of ​​the container from above should also be chemically prestressed on one side, the container can be immersed in the brine bath to a deeper extent starting from the bottom, but care should be taken not to allow the brine bath to enter the opening to prevent chemical changes to the inner surface of the container. For this purpose, the opening can be sealed, for example, with a stopper, so that the container can be completely submerged.

[0098] Another embodiment specifies that the container is first immersed in the brine bath along a direction of movement parallel to the container's longitudinal axis and perpendicular to the surface of the brine bath. This prevents the brine solution from entering the hollow body due to the air present within it. A disadvantage of this method is that steam from the brine bath may enter the opening if it is not properly sealed beforehand. Attached Figure Description

[0099] The invention will now be described with reference to the accompanying drawings and preferred embodiments, in which:

[0100] Figure 1 An exemplary vial illustrates at least a partial cross-sectional view of a glass container according to the invention, used to contain a formulation, the cross-section extending substantially vertically through the center of the container.

[0101] Figure 2 The cross-sectional view schematically illustrates a section of the wall in the region of the sidewall, which extends substantially vertically through the center of the container.

[0102] Figure 3-6 The results of strength tests on glass containers are shown, comparing and analyzing containers of borosilicate glass and aluminosilicate glass with unstressed containers, respectively, with those that are externally prestressed on one side.

[0103] Figure 7 An example illustrates the stress ratio generated in the wall thickness direction due to unilateral prestressing.

[0104] Figure 8 The stress patterns from the outer surface to the inner surface of the wall illustrate the modes of (positive) compressive stress and (negative) tensile stress in the wall.

[0105] Figure 9 An exemplary vial illustrates a glass container according to the invention, wherein a stopper having a stainless steel body has been inserted into the opening of the container for a liquid-tight seal. The view is at least a partial cross-sectional view that extends substantially vertically through the center of the container. Detailed Implementation

[0106] In the following detailed description of preferred embodiments, for simplicity, the same reference numerals denote substantially the same parts in these embodiments or on these embodiments.

[0107] To better understand this, the following definitions are provided.

[0108] For the purposes of this invention, the term "region" is understood to refer to a spatial volume that is entirely within the glass but may be adjacent to the glass surface. For the purposes of this invention, the term "surface" should be understood not as a mathematical concept of surface but as a physical concept, wherein the surface comprises at least one or more atomic or molecular layers of the glass such that their physical properties, such as compressive or tensile stress, can be measured on both the inner and outer surfaces.

[0109] The concept of a layer can include the aforementioned region, and a layer is conceptually consistent with the aforementioned region when that region extends near the surface, for example, along a surface (e.g., the outer surface), and thereby occupies a spatial volume. In this case, the concepts of region and layer are used synonymously, although such a layer is typically composed of the inherent material of glass, but can be heat-treated or chemically treated.

[0110] Figure 1 An exemplary vial 10 illustrates a glass container 1 according to the invention, which is used to contain a formulation (not shown). Container 1 includes a hollow body defining an internal volume 12 for containing the formulation. Container 1 can, of course, also be a container of other geometries without limiting the exemplary embodiments described, such as an ampoule, syringe, or cartridge.

[0111] The hollow body includes a wall 11 having an inner surface 14 pointing toward the internal volume 12 of the hollow body and an outer surface 13 arranged opposite to the inner surface 14, the outer surface 13 pointing toward the external environment. The rotationally symmetric hollow body includes a cylindrical or tubular portion having an upper end 15 and a lower end 16, and the upper end 15 includes an opening 17 for filling or emptying the hollow body.

[0112] In the exemplary vial 10 shown, the wall 11 of the hollow body includes sidewalls 20 and a bottom 22, and has a rounded edge in the transition region between the bottom 22 and the sidewalls 20, referred to as the heel 21. Thus, the bottom forms the lower end of the hollow body. In the example of vial 10, a shoulder 23 forms the upper end of the sidewalls 20, which becomes the neck 24. The neck 24 finally abuts the end at the upper end 15, which is also indicated as a rolled edge 25 in the example of vial 10. Those skilled in the art will recognize that these markings on the wall 11 relate to the depicted vial 10, and that other designations apply when the container is of other shapes, such as when depicted as an ampoule, syringe, or cartridge. Therefore, the unilateral external prestressing according to the invention naturally relates not only to vials, but generally to glass containers with different geometries.

[0113] Independent of the specific geometry of container 1, the lower part A and the adjacent part B of the container can be defined. The lower part A includes the region starting from the lower end 16 of the container and the region that substantially forms the internal volume of the hollow body. The adjacent part B refers to the upper region of the container.

[0114] The depicted vial 10 is manufactured by first drawing a portion of a glass tube and then thermoforming it. In this example, the vial 10 is made of borosilicate glass, but other glass compositions suitable for, for example, primary packaging of pharmaceuticals, may also be selected to manufacture the vial 10.

[0115] Borosilicate glass has high resistance to chemical leaching and is advantageous for pharmaceutical applications, for example, as defined in the European Pharmacopoeia 8.4: containers made of borosilicate glass are advantageously classified as corresponding to type I, which corresponds to the category with the highest resistance.

[0116] According to the invention, the outer surface 13 of the wall 11 includes an externally arranged layer or region with compressive stress, such that the wall 11 is at least partially compressively prestressed from the outside. This region with compressive stress extends into the wall 11 to a depth DOL, the wall itself having a thickness t.

[0117] Figure 2 The cutout in wall 11 is shown only schematically, in this example, the region of sidewall 20 having an outer surface 13 and an inner surface 14. Starting from the outer surface 13 of wall 11, in the direction of the center 35 of wall 11, the outer surface 13 is adjacent to a region 30 with compressive prestressing. It can be clearly seen that this region 30 does not extend to the center 35 of wall 11, particularly the region of wall 11 located between the center 35 of the wall and the inner surface 14. Therefore, there is no compressive stress on the opposite inner surface 14 of the wall, but rather tensile stress. Thus, it is clear that this is a container with unilateral external prestressing according to the invention.

[0118] Therefore, only those areas of container 1 are preferably provided with unilateral external compressive prestress, which mainly bears the critical load.

[0119] In many cases, such as through Figure 2 As illustrated in the example, this involves the sidewall 20, as this is where impacts and radial loads can occur, especially during transport. During filling, higher compressive forces may be introduced, affecting the interior of container 1, and axial loads may also be added, for example, during sealing. Therefore, it is evident that, in the areas of the heel 21 and the bottom 22, i.e., in the portion of container 1 marked A, unilateral external compressive prestressing should also be provided to the wall 11 according to the invention.

[0120] In many cases, it is more convenient to provide unilateral external compression prestressing to the entire outer area of ​​the container, i.e. the area belonging to part B, including the shoulder 23, neck 24 and hem 25, according to the present invention.

[0121] Figure 2 The wall thickness t of container 1 is not limited to the exemplary embodiment of approximately t = 1 mm; for example, a wall thickness of t = 1.6 mm is also feasible. Here, thermal prestressing is difficult to achieve, therefore the vial 10 is chemically prestressed. For this purpose, container 1 is exposed to a saline bath containing potassium nitrate (KNO3) at a high temperature of approximately 400°C or higher for 1 to 24 hours, or possibly 1 to 8 hours. However, this temperature should be maintained below the glass transition temperature Tg of the glass, but for some types of glass it may be 450°C or even 490°C.

[0122] Chemical prestressing leads to the enrichment of potassium ions from the brine bath, which in turn enrich at the locations of smaller sodium ions present in the glass near the surface layer. This near-surface layer represents region 30. After chemical prestressing, the strength of this layer, as well as the outer surface 13 of container 1, is higher than that of the untreated surface.

[0123] Inside the wall 11, that is, in the direction from the outer surface 13 toward the inner surface 14, tensile stress is generated due to external prestressing, which offsets the compressive stress.

[0124] exist Figure 2 The thickness of the prestressed layer on the outer surface 13 of wall 11, known as DOL, is shown purely for illustration purposes, where an actual thickness is chosen. In practice, DOL is typically tens of micrometers, approximately 35 μm in this example, where a range of 10 μm to 100 μm is generally considered appropriate.

[0125] The unilaterally externally prestressed container 1 has increased strength during filling and / or sealing, and also has good strength under axial or radial impact or collision, for example, this may occur during automated transport.

[0126] By combining appropriate simulations with structural mechanics modeling, it can be demonstrated that, due to unilateral prestressing, the tensile stress typically present in the central region of the glass extends all the way to the inner surface of the hollow body wall. The tension distribution in the wall 11 of the hollow body of the container 1 according to the present invention is expressed as follows:

[0127] IST=0.5x(CS x DOL) / (t-DOL).

[0128] Where t represents the thickness of the wall.

[0129] Figures 3 to 7 The results of strength tests on glass containers 1 are shown, wherein, according to the present invention, various tests were performed on unilaterally externally prestressed containers 1 (each container having a nominal volume of 2 ml (2R vials)) of borosilicate glass and aluminosilicate glass, forming test batches of 50 containers respectively. In the case of borosilicate glass, the maximum compressive prestress of the resulting compressive prestressed surface layer was approximately CS = 200 MPa, DOL = 35 μm. In the case of aluminosilicate glass, the maximum compressive prestress of the resulting compressive prestressed surface layer was approximately CS = 800 MPa, DOL = 55 μm. They were compared with samples of the same material and the same geometry.

[0130] Borosilicate glass is understood herein by those skilled in the art to be, in particular, glass having the following composition (in weight percent):

[0131]

[0132] Aluminosilicate glass may preferably have the following components (in weight percent):

[0133]

[0134] Glass Rupture pressure Axial compression Diameter compression Pendulum Impact External prestressing only BS 0.96 1.58 2.13 2.56 External prestressing only AS 0.64 1.51 2.52 6.40

[0135] The table above shows the relative improvement of the 1st percentile based on external prestressing compared to the 1st percentile of unprestressed containers. The abbreviation BS here represents borosilicate glass, and the abbreviation AS represents aluminosilicate glass. Therefore, the details given above are relative measures for improving the performance of containers according to the invention, compared to conventional unprestressed containers.

[0136] The rupture pressure was determined according to the test procedure of DIN EN ISO 7458 (“Glass containers – Internal pressure resistance, test method”). This involves subjecting the container to hydraulic pressure inside. The pressure is continuously increased at a rate of 5.8 bar per second until the container ruptures.

[0137] The mechanical resistance of a container to axial compression is determined according to the test procedure in DIN EN ISO 8113 (“Glass containers – Resistance to vertical loads – Test method”). This involves subjecting the container to an axial compressive force that increases at a constant rate of 500 N per minute until the container ruptures.

[0138] According to the test procedures of DIN EN ISO 8113, the mechanical resistance to radial or diametrical compression can also be determined.

[0139] The pendulum impact test is described in DIN 52295.

[0140] To determine the so-called burst pressure, burst tests are used to determine the strength during the filling and / or sealing and / or freeze-drying processes. During these burst tests, the internal pressure increases sharply, causing the corresponding container to burst. Figure 3 The results of this rupture test are shown. The figure shows the 1% quantiles, where the 1% quantile for the unstressed borosilicate glass container in each test is normalized to 1. Clearly, when the container is borosilicate glass, the rupture pressure remains virtually unchanged in the case of a borosilicate glass container with unilateral external prestressing, while the rupture pressure decreases in the case of an aluminosilicate glass container with unilateral external prestressing.

[0141] exist Figure 4 The results show test results for axial load conditions that may occur, for example, during container filling. The 1% quantile is again indicated separately. Clearly, the unilateral external prestressing of the borosilicate glass container according to the invention significantly increases the container's strength. However, the strength increase of the borosilicate glass container is greater than that of an aluminosilicate glass container undergoing the same strength increase.

[0142] exist Figure 5 The test results for radial load conditions are shown, i.e., the test results for forces radially impacting the outer surface of the container (e.g., forces that may occur during transportation). The corresponding 1st percentile is shown again. Clearly, the unilateral external prestressing of the borosilicate glass container according to the invention also results in a very significant increase in container strength.

[0143] exist Figure 6The results of the pendulum impact test are shown, with the loads that could be applied to the container due to the impact expressed as the 1st percentile. Similarly, it is clear that the unilateral external prestressing of the borosilicate glass container according to the invention also results in a significant increase in container strength. Here, the strength increase of the aluminosilicate glass container may be even greater than that of the borosilicate glass container.

[0144] The last three tests mentioned—axial compression and diametrical or radial compression tests on the container, and pendulum impact test—show that the container's strength has been significantly improved.

[0145] As an example, Figure 7 The stress pattern formed across the wall thickness due to unilateral prestressing is shown. Clearly, the tensile stress CT, which typically occurs at the center, approximately 35° from the center of the wall, extends all the way to the inner surface of the vessel wall.

[0146] The formation of tensile stress on the inner surface of the wall is an essential characteristic of the overall strength of the container, especially in the case of external impacts and axial or radial external shocks, where the magnitude of this characteristic has a major influence on strength. According to the invention, it is advantageous that the tensile stress on the inner surface of the wall does not become too large to prevent deterioration of the burst pressure resistance.

[0147] In summary, an asymmetric profile of stress patterns appears in the wall relative to the center of the wall, wherein the outer half of the wall contains (positive) compressive stress on average, while the inner half of the wall contains (negative) tensile stress.

[0148] As an example, Figure 8 The patterns of (positive) compressive stress and (negative) tensile stress in the wall are schematically illustrated. The stress patterns from the outer surface to the inner surface of the wall are depicted.

[0149] In a preferred embodiment, a stress mode exists in the wall 11 of the container 1 that transitions from a high compressive prestress on the outer surface to a relatively low level of tensile stress, which can be expressed as:

[0150] 0.3*(CS x DOL) / (t—DOL) <IST<0.7*(CS x DOL) / (t—DOL)。

[0151] Therefore, a glass container can be provided that incorporates a very favorable relationship, namely, that when the internal pressure of the container increases (if any), the increase in strength decreases very little.

[0152] As shown above, through this relationship, the acceptable reduction in fracture pressure is up to 20%, but a significant increase in strength can still be achieved, as further demonstrated by the reference measurements above, which are shown in the form of 1% quantiles.

[0153] Here, at least a portion of the tensile stress region on the inner surface of the wall can be located between IST>=0 MPa and IST<=30 MPa, preferably IST<=20 MPa, particularly preferably IST<=15 MPa, and most preferably IST<=5 MPa. In this way, it can also be ensured that the tensile stress caused by the prestress does not become too large, so that the rupture characteristics of the container 1 hardly deteriorate, or preferably do not deteriorate.

[0154] In this example, the tensile stress pattern from the center 35 of the wall of the container 1 of the present invention to the inner surface of the wall is constant, that is, the level of tensile stress at the center of the wall is approximately equal to the level of tensile stress on the inner surface of the wall. In a preferred embodiment, the level of tensile stress from the center of the wall to the inner surface of the wall is subject to only a small fluctuation, preferably within + / -10%, more preferably within + / -5%.

[0155] Therefore, the container according to the invention is further characterized in that only the outer surface of the wall has a near-surface compressive prestress zone with a thickness of DOL, which is no more than 15%, preferably no more than 10%, and particularly preferably no more than 8% of the wall thickness.

[0156] In a particularly preferred embodiment, the thickness of the near-surface compressive prestressed zone on the outer surface of the wall is no greater than 6% relative to the wall thickness t. Therefore, in the case of a wall thickness, for example, t = 1.6 mm, the thickness of the near-surface compressive prestressed zone is DOL = 96 μm. Thus, the effect of highly reliable prestressing, particularly under chemical prestressing, is achieved, i.e., the region whose composition is altered and enriched with potassium ions due to prestressing is limited to the outer surface.

[0157] Therefore, the central region of the wall and the inner region extending from the center of the wall to the inner surface of the wall are preferably free of additional alkali metals, preferably potassium ions, introduced by prestressing. Generally, at least in the region 0.5 μm from the outer surface up to 0.5 μm from the inner surface, the distribution of alkali metals introduced by prestressing monotonically decreases from the outer surface of the wall toward the inner surface.

[0158] Therefore, the amount of K2O and Na2O on the inner surface of the wall is preferably no more than 10%, preferably no more than 9%, and particularly preferably no more than 8%. According to the invention, this amount is measured on the inner surface of the wall at a moderate height as viewed from the bottom. In summary, in Figure 2 The wall 11 shown exhibits a concentration pattern of alkali ions introduced through exchange, which decreases from a high value near the outer surface of the wall to a low value on the inner surface.

[0159] Therefore, a key advantage of this invention is that the inner surface of the container, which interacts with the drug, remains chemically unchanged and is thus chemically inert. This is particularly advantageous for containers intended to hold cosmetic, medical, or pharmaceutical preparations.

[0160] Simultaneously, the strength of the container according to the invention can be increased, thereby significantly improving the product reliability of the container, especially during transportation and / or filling. Furthermore, when a container is sealed, for example with a closure such as a stopper, high internal pressure is generated, which can lead to rupture. Here, the reliability of the container according to the invention is also improved.

[0161] According to the invention, a primary glass packaging for pharmaceuticals with enhanced strength can also be provided, wherein the inner surface of the container wall in contact with the formulation (e.g., a drug) has no chemical change compared to the surface of a container that has not been prestressed. Therefore, the formulation, for example, the drug, also only comes into contact with the original, unaltered glass surface.

[0162] Various embodiments are applicable to this method depending on the expected amount of prestressing. For example, if chemical prestressing is performed only on the exterior, unilaterally, on the bottom and / or heel and / or sidewalls (i.e., substantially on...). Figure 1 The portion of container 1 (represented by A) is clearly immersed in the salt bath from the bottom. If the adjacent portion B above the container is also to be chemically prestressed unilaterally from the outside, the container can be immersed deeper into the salt bath from the bottom. However, care should be taken to prevent the salt bath from entering the opening to avoid chemical changes to the inner surface of the container. For this purpose, the opening can be conveniently sealed, for example, using a stopper.

[0163] exist Figure 9 An exemplary stopper is shown, wherein a stainless steel body 40 with a lateral overhang 41 is inserted into the opening of a container 1 (particularly a vial 10). The body is generally T-shaped in cross-section, and its portions are cylindrical. The stainless steel body 40 includes a recess 42 within its interior, the recess 42 including a sidewall region 44, the wall thickness of which is reduced to about 10 to 100 μm. The sidewall region 44 includes an outwardly arched protrusion, the protrusion... Figure 9 It is difficult to identify in the middle, but it can be inserted into a container that has elastic lateral support against container 1 in opening 17.

[0164] The bottom 45 of the stainless steel body 40 includes a blind hole 46 with internal threads that engages with the external threads of a threaded pin 47, which includes a laterally overhanging head.

[0165] By tightening the threaded pin 47, the stainless steel body 40 can be compressed, and with increasing tightening, the stainless steel body 40 is pressed more and more tightly against the side wall region 44 of the glass of container 1, until sufficient liquid-tight contact is achieved with respect to the aforementioned chemical hardening. The location of this liquid-tight contact is as follows: Figure 9 As shown.

[0166] The process of inserting the stainless steel body and creating liquid-tight contact can be performed manually or with the help of automated process tools.

[0167] If the process is carried out as part of an automated production process, the stainless steel body 40, particularly its side overhangs 41, can serve as a retainer for the container 1. This body is directly attached to the container after thermoforming and remains attached until the end of the handling and processing, especially until prestressing is performed. This reliably protects the container 1 from mechanical loads impacting its surface during manufacturing or transportation.

[0168] Another embodiment specifies that the container head is first immersed in a direction of movement parallel to the longitudinal axis of the container and perpendicular to the surface of the salt bath, so that the air present in the hollow body can prevent the salt water solution from entering the hollow body.

Claims

1. A container comprising or made of glass, said container comprising a hollow body having an internal volume. The hollow body includes a wall having an inner surface and an outer surface opposite to the inner surface, the inner surface defining the internal volume of the hollow body. in, The wall includes, at least in a portion of its area, regions with compressive stress. The region with compressive stress is formed on the wall adjacent to the outer surface. In the center of the wall, that is, in the center between the outer surface and the inner surface, the tensile stress CT is expressed as CT≥0 MPa and CT<15 MPa.

2. The container of claim 1, wherein the container is used to contain a formulation, the formulation being contained within the internal volume of the hollow body.

3. The container according to claim 1 or 2, wherein the tensile stress CT ≤ 5 MPa.

4. The container according to claim 1 or 2, wherein the wall of the hollow body forms at least one opening and / or a rolled edge and / or a neck and / or a shoulder and / or a side wall and / or a heel and / or a bottom.

5. The container of claim 4, wherein regions comprising compressive stress are formed in the vicinity of the shoulder, neck, edging, sidewalls, heel and / or bottom and / or adjacent to the shoulder, neck, edging, sidewalls, heel and / or bottom.

6. The container according to any one of claims 1 or 2, characterized in that, The container is a vial, ampoule, syringe, or cartridge.

7. The container according to any one of claims 1 or 2, characterized in that, Since the region of compressive stress is formed on the wall adjacent to the outer surface, compressive stress is formed in the region of the outer surface up to depth DOL, and there is an asymmetrical profile of stress mode from the outer surface of the wall to the opposite inner surface in the radial direction relative to the center of the wall.

8. The container according to claim 1 or 2, characterized in that, In the region of compressive stress in the outer surface, the inner surface tension is formed as tensile stress on the inner surface of the wall opposite to that region, and the tensile stress IST is expressed as: IST≥0MPa and IST≤30 MPa.

9. The container according to claim 8, wherein IST ≤ 20 MPa.

10. The container according to claim 8, wherein IST ≤ 15 MPa.

11. The container according to claim 8, wherein IST ≤ 5 MPa.

12. The container according to claim 1 or 2, characterized in that, In the region of compressive stress on the outer surface, the tensile stress on the opposite inner surface of the wall is expressed as: ， Where DOL represents the depth of the region where compressive stress exists. t represents the thickness of the wall, and CS represents the compressive stress on the outer surface.

13. The container according to claim 1 or 2, characterized in that, In the region of compressive stress in the outer surface, the tensile stress level at the center of the wall is approximately equal to the tensile stress level on the opposite inner surface of the wall, and wherein the tensile stress level from the center of the wall to the inner surface of the wall is subject to only small fluctuations within + / - 10%.

14. The container of claim 13, wherein the fluctuation range is within + / - 5%.

15. The container according to claim 1 or 2, characterized in that, For regions with compressive stress on the outer surface, the thickness or depth DOL of the near-surface compressive prestressed region shall not exceed 15% relative to the wall thickness or wall width in that region.

16. The container of claim 15, wherein the thickness or depth DOL of the near-surface compression prestressed region does not exceed 10% relative to the wall thickness or wall width in that region.

17. The container of claim 15, wherein the thickness or depth DOL of the near-surface compression prestressed region does not exceed 8% relative to the wall thickness or wall width in that region.

18. The container of claim 15, wherein the thickness or depth DOL of the near-surface compression prestressed region does not exceed 6% relative to the wall thickness or wall width in that region.

19. The container according to claim 1 or 2, characterized in that, When prestressing is introduced chemically in a region with compressive stress, the distribution of alkali metal elements introduced into the glass during chemical prestressing monotonically decreases from the outer surface toward the wall relative to the inner surface in the region 0.5 µm from the outer surface to 0.5 µm from the inner surface.

20. The container according to claim 19, wherein the alkali metal element is potassium.

21. The container according to claim 1 or 2, characterized in that, At least in the region of compressive stress on the outer surface, relative to the glass at the center of the wall, the glass on the opposite inner surface of the wall up to a depth of 100 μm does not contain a certain concentration of additional alkali metal substances introduced into the glass.

22. The container according to claim 1 or 2, characterized in that, At least in the region of compressive stress on the outer surface, relative to the glass at the center of the wall, the glass on the opposite inner surface of the wall up to a depth of 150 μm does not contain a certain concentration of additional alkali metal substances introduced into the glass.

23. The container according to claim 1 or 2, characterized in that, At least in the region of compressive stress on the outer surface, relative to the glass at the center of the wall, the glass on the opposite inner surface of the wall up to a depth of 200 μm does not contain a certain concentration of additional alkali metal substances introduced into the glass.

24. The container according to claim 1 or 2, characterized in that, At least on the inner surface of the wall opposite the area with compressive stress, the average content of K2O + Na2O up to a depth of 500 μm does not exceed 13% by weight.

25. The container of claim 24, wherein the average content of K2O + Na2O up to a depth of 500 μm does not exceed 9% by weight.

26. The container of claim 24, wherein the average content of K2O + Na2O up to a depth of 500 μm does not exceed 8% by weight.

27. The container according to claim 1 or 2, characterized in that, In regions of the outer surface that exhibit compressive stress, the compressive stress is generated thermally or chemically.

28. The container according to claim 1 or 2, characterized in that, The glass comprises a glass composition suitable for primary packaging of pharmaceuticals.

29. The container according to claim 1 or 2, wherein the glass comprises borosilicate glass or aluminosilicate glass.

30. A method for chemically prestressing a container according to any one of claims 1 to 29, Starting from the bottom, the hollow body is immersed in a brine bath containing potassium nitrate (KNO3) to a predetermined depth at a high temperature of at least 400°C but below the Tg of glass for 1 to 24 hours to generate compressive stress at least locally on the outer surface, so that the outer wall is at least locally prestressed by compression.

31. The method of claim 30, wherein the duration is 1 to 8 hours.

32. A method for chemically prestressing a container according to any one of claims 1 to 29, Starting from the opening, the container is immersed in a brine bath containing potassium nitrate (KNO3) to a predetermined depth at a high temperature of at least 400°C but below the Tg of the glass for a duration of 1 to 24 hours, so as to generate at least locally a layer of compressive stress on the outer surface of the wall, such that the outer wall is at least locally compressively prestressed.

33. The method of claim 32, wherein the duration is 1 to 8 hours.

34. The method of claim 30 or 32, wherein the opening of the container is sealed before immersion.

Images