GLASS COMPOSITIONS WITH IMPROVED CHEMICAL AND MECHANICAL DURABILITY

Abstract

The embodiments described herein relate to chemically and mechanically durable glass compositions, and glass articles formed therefrom; in another embodiment, a glass composition may include from approximately 70 mol% to approximately 80 mol% SiO2; from approximately 3 mol% to approximately 13 mol% alkaline earth oxide; X mol% Al2O3; and Y mol% alkali oxide; the alkali oxide may include Na2O in an amount greater than approximately 8 mol%; the ratio Y:X may be greater than 1, and the glass composition may be free from boron and boron compounds; in some embodiments, the glass composition may also be free from phosphorus and phosphorus compounds;Glass articles formed from the glass composition may have an acid resistance of at least class S3 according to DIN 12116, a base resistance of at least class A2 according to ISO 695, and a hydrolytic resistance of type HGA1 according to ISO 720.

Description

GLASS COMPOSITIONS WITH IMPROVED CHEMICAL AND MECHANICAL DURABILITY CROSS REFERENCE TO RELATED APPLICATIONS The present application claims priority from U.S. provisional patent application series No. 61 / 551,163, filed on October 25, 2011 (Attorney Case No. SP11-240P) and entitled “Glass Compositions With Improved Chemical and Mechanical Durability”, the entirety of which is incorporated herein by reference. FIELD OF INVENTION In general, this specification relates to glass compositions, and more specifically to chemically and mechanically durable glass compositions that are suitable for use in pharmaceutical packaging. BACKGROUND OF THE TECHNIQUE Historically, glass has been the preferred material for packaging pharmaceuticals due to its airtightness, optical transparency, and excellent chemical durability compared to other materials. Specifically, glass used for pharmaceutical packaging must have adequate chemical durability to avoid affecting the stability of the pharmaceutical compositions it contains. Glasses with adequate chemical durability include glass compositions within the ASTM standard for Type 1B glass compositions, which have a proven track record of chemical durability. However, the use of glass for these applications is limited by its mechanical performance. Specifically, in the pharmaceutical industry, glass breakage poses a safety risk to the end user, as the broken container and / or its contents can cause injury. Breakage can be costly for pharmaceutical manufacturers because breakage within a filling line necessitates the disposal of neighboring unbroken containers, as they may contain fragments from the broken container. Breakage can also require delaying or stopping the filling line, decreasing production output. Furthermore, breakage can result in the loss of the active pharmaceutical ingredient, leading to increased costs.Furthermore, non-catastrophic breakage (i.e., when the glass cracks but does not break) can cause the contents to lose their sterility, which in turn can result in costly product recalls. One proposal to improve the mechanical durability of glass containers is to thermally temper them. Thermal tempering strengthens the glass by inducing a compressive surface stress during rapid cooling after forming. This technique works well with glass articles with flat geometries (such as windows), glass articles with thicknesses > 2 mm, and glass compositions with high thermal expansion. However, pharmaceutical glass containers typically have complex geometries (vials, tubes, ampoules, etc.), thin walls (-1-1.5 mm), and are produced from low-expansion glass (30-55 x 10⁻⁷ K⁻¹), making them unsuitable for strengthening by thermal tempering. Chemical tempering also strengthens glass by introducing compressive surface stress. This stress is introduced by immersing the item in a molten salt bath. As the glass ions are replaced by larger molten salt ions, compressive stress is induced on the glass surface. The advantage of chemical tempering is that it can be used on complex geometries and thin samples, and it is relatively insensitive to the thermal expansion characteristics of the glass substrate. However, glass compositions that exhibit moderate susceptibility to chemical tempering generally exhibit low chemical durability, and vice versa. Therefore, there is a need for glass compositions that are chemically durable and amenable to chemical strengthening by ion exchange, for use in pharmaceutical glass containers and similar applications. bnoi i η / ι ζπζ / β / υιλι BRIEF DESCRIPTION OF THE INVENTION According to one specification, a glass composition may include: SiO2 in a concentration greater than approximately 70 mol% and Y mol% of alkali oxide. The alkali oxide may include Na2O in an amount greater than approximately 8 mol%. The glass composition may be free of boron and boron compounds. According to another modality, a glass composition may include: more than approximately 68 mol% of SiO2; X mol% of Al2O3; Y mol% of alkali oxide; and B2O3. The alkali oxide may include Na2O in an amount greater than approximately 8 mol%. The ratio (B2O3 (mol%) / (Y mol% - X mol%)) may be greater than 0 and less than 0.3. In another form, a glass article may have a hydrolytic resistance type HGB1 according to ISO 719. The glass article may include more than approximately 8 mol% of Na2O and less than approximately 4 mol% of B2O3. In another embodiment, a pharmaceutical glass container may contain: SiO2 in an amount greater than approximately 70 mol%; X mol% of Al2O3; and Y mol% of alkali oxide. The alkali oxide may contain Na2O in an amount greater than approximately 8 mol%. The ratio of the concentration of B2O3 (mol%) in the pharmaceutical glass container to (Y mol% - X mol%) may be less than 0.3. The pharmaceutical glass container may also have a hydrolytic resistance HGB1 according to ISO bnoi 1 η / ι ζπζ / β / υιλι hnoi > κ C κ. 5 719. In another embodiment, a glass composition may include approximately 70 mol% to approximately 80 mol% S1O2; approximately 3 mol% to approximately 13 mol% alkaline earth oxide; X mol% Al2O3; and Y mol% alkali oxide. The alkali oxide may include Na2O in a greater amount of approximately 8 mol%. The Y:X ratio may be greater than 1, and the glass composition may be free of boron and boron compounds. In another embodiment, a glass composition may include: from approximately 72 mol% to approximately 78 mol% of S1O2; from approximately 4 mol% to approximately 8 mol% of alkaline earth oxide; X mol% of Al2O3; and Y mol% of alkali oxide. The amount of alkaline earth oxide may be greater than or equal to approximately 4 mol%, and less than or equal to approximately 8 mol%. The alkali oxide may include NazO in an amount greater than or equal to approximately 9 mol%, and less than or equal to approximately 15 mol%. The Y:X ratio may be greater than 1. The glass composition may be free of boron and boron compounds. In another embodiment, a glass composition may include: from approximately 68 mol% to approximately 80 mol% of S1O2; from approximately 3 mol% to approximately 13 mol% of alkaline earth oxide; X mol% of Al2O3; and Y mol% of alkali oxide. The alkali oxide may include NaZO in an amount greater than approximately 8 mol%. The glass composition may also include B2O3. The ratio (B2O3 (mol%) / (Y mol% - X mol%)) may be greater than 0 and less than 0.3, and the ratio Y:X may be greater than 1. In another embodiment, a glass composition may include from approximately 70 mol% to approximately 80 mol% SiO2; from approximately 3 mol% to approximately 13 mol% alkaline earth oxide; X mol% Al2O3; and Y mol% alkali oxide. The alkaline earth oxide may include CaO in an amount greater than or equal to approximately 0.1 mol%, and less than or equal to approximately 1.0 mol%. X may be greater than or equal to approximately 2 mol%, and less than or equal to approximately 10 mol%. The alkali oxide may include from approximately 0.01 mol% to approximately 1.0 mol% K2O. The ratio Y:X may be greater than 1. The glass composition may be free of boron and boron compounds. In another embodiment, a glass composition may include SiO2 in an amount greater than approximately 70 mol% and less than or equal to approximately 80 mol%; from approximately 3 mol% to approximately 13 mol% of alkaline earth oxide; X mol% of Al2O3; and Y mol% of alkali oxide. The alkali oxide may include Na2O in an amount greater than approximately 8 mol%. The ratio of the concentration of B2O3 (mol%) in the glass composition to (Y mol% - X mol%) may be less than 0.3. The ratio Y:X may be greater than 1. In another form, a glass article may have a type of hydrolytic resistance HGB1 according to ISO 719. The glass article may also have a threshold diffusivity greater than 16 pm2 / ha at a temperature less than or equal to 450°C. In another embodiment, a glass article may have a hydrolytic resistance type HGB1 according to ISO 719. The glass article may also have a compressive strength layer with a layer depth greater than 25 pm and a surface compressive strength greater than or equal to 350 MPa. The glass article may be ion-exchange strengthened, and the ion-exchange strengthening may include treatment of the glass article in a molten salt bath for a time less than or equal to 5 hours at a temperature less than or equal to 450°C. Additional features and advantages will be indicated in the following detailed description, and some of them will be readily apparent to those skilled in the art from this description or will be recognized by practicing the methods described herein, including the following detailed description, the claims, and the accompanying drawings. It should be understood that both the preceding general description and the following detailed description describe various forms and are intended to provide an overview or panorama for understanding the nature and character of the claimed material. The accompanying drawings are included to provide a further understanding of the various forms and are incorporated into and form part of this specification. The drawings illustrate the various forms described and, together with the description, serve to explain the principles and operations of the claimed material. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 graphically represents the relationship between the alkali oxide to alumina ratio (x-axis) and the strain point, annealing point, and softening point (y-axis) of glass compositions of the invention and comparative compositions. Figure 2 graphically represents the relationship between the alkali oxide to alumina ratio (x-axis) and the maximum compressive stress and stress change (y-axis) of glass compositions of the invention and comparative compositions. Figure 3 graphically represents the relationship between the alkali oxide to alumina ratio (x-axis) and the hydrolytic resistance determined according to ISO 720 (y-axis) of glass compositions of the invention and comparative compositions. Figure 4 graphically represents the diffusivity D (y-axis) as a function of the ratio (CaO / (CaO+MgO)) (x-axis) of glass compositions of the invention and comparative compositions. Figure 5 graphically represents the maximum compressive stress (y-axis) as a function of the ratio (CaO / (CaO+MgO)) (x-axis) of glass compositions of the invention and comparative compositions. bnoi i η / ι ζπζ / β / υιλι Figure 6 graphically represents the diffusivity D (y-axis) as a function of the ratio (BzOs / ÍRzO-AbOa)) (x-axis) of glass compositions of the invention and comparative compositions. Figure 7 graphically represents the hydrolytic resistance determined according to ISO 720 (y-axis) as a function of the ratio (B2O3 / (R2O-Al2O3)) (x-axis) of glass compositions of the invention and comparative compositions. DETAILED DESCRIPTION OF THE INVENTION Several types of glass compositions exhibiting improved chemical and mechanical durability will now be discussed in greater detail. These glass compositions are suitable for use in various applications, including, but not limited to, pharmaceutical packaging materials. The glass compositions can also be chemically strengthened, thereby imparting greater mechanical durability. The glass compositions described herein generally comprise silica (S1O2), alumina (Al2O3), alkaline earth oxides (such as MgO and / or CaO), and alkali oxides (such as NaZO and / or K2O), in quantities that impart chemical durability to the glass composition. Furthermore, the alkali oxides present in the glass compositions facilitate chemical strengthening of the glass compositions through ion exchange.Several forms of glass compositions will be described in this document, and further illustrated by reference to specific examples. The term softening point, as used herein, refers to the temperature at which the viscosity of the glass composition is 1 x107·6poise. The term annealing point, as used herein, refers to the temperature at which the viscosity of the glass composition is 1x1013poise. The terms strain point and strain temperature, as used herein, refer to the temperature at which the viscosity of the glass composition is 1 x1014 poise. The term CTE, as used herein, refers to the coefficient of thermal expansion of the glass composition over a temperature scale from approximately ambient temperature (ta) to approximately 300°C. In the forms of glass compositions described herein, the concentrations of the constituent components (for example, SiO2, Al2O3 and the like) are specified in molar percentage (% molar) on an oxide basis, unless otherwise specified. The terms "free" and "substantially free," used to describe the concentration and / or absence of a particular constituent component in a glass composition, mean that the constituent component is not intentionally added to the glass composition. However, the glass composition may contain traces of the constituent component as a contaminant in amounts less than 0.01 mol%. The term chemical durability, as used herein, refers to the ability of the glass composition to resist degradation following exposure to specified chemical conditions. Specifically, the chemical durability of the glass compositions described herein was evaluated according to three established material testing standards: DIN 12116, March 2001, entitled “Glass testing – Resistance to attack by a boiling aqueous solution of hydrochloric acid – Test method and classification”; ISO 695:1991, entitled “Glass – Resistance to attack by a boiling aqueous solution of mixed alkali – Test method and classification”; and ISO 720:1985, entitled “Glass – Hydrolytic resistance of glass grains at 121°C – Test method and classification”.The chemical durability of glass can also be assessed according to ISO 719:1985, “Glass - Hydrolytic resistance of glass grains at 98°C - Test method and classification”, in addition to the standards mentioned above. ISO 719 is a less stringent version of ISO 720, and therefore glass that meets a specified classification under ISO 720 is generally considered to meet the corresponding classification under ISO 719. The classifications associated with each standard are described in more detail herein. bnoi i η / ι ζπζ / β / υιλι The glass compositions described herein are alkali aluminosilicate glass compositions that may generally include a combination of SiO2 and one or more alkali oxides, such as Na2O and / or K2O. The glass composition may also include Al2O3 and at least one alkaline earth oxide. In some embodiments, the glass compositions may be free of boron and boron-containing compounds. The glass compositions are resistant to chemical degradation and are also suitable for chemical strengthening by ion exchange. In some embodiments, the glass compositions may additionally comprise minor amounts of one or more additional oxides, such as SnO2, ZrO2, ZnO, T1O2, As2O3, or the like. These components may be added as clarifying agents and / or to further increase the chemical durability of the glass composition. In the glass compositions described herein, SiO2 is the major constituent and therefore the primary constituent of the resulting glass network. SiO2 increases the chemical durability of the glass and, in particular, its resistance to acid decomposition and water decomposition. Consequently, a high SiO2 concentration is generally desirable. However, if the SiO2 content is too high, the formability of the glass may decrease, as high SiO2 concentrations increase the difficulty of melting the glass, which in turn adversely affects its formability.In the embodiments described herein, the glass composition generally comprises SiO2 in an amount greater than or equal to 67 mol%, and less than or equal to approximately 80 mol%, or even less than or equal to 78 mol%. In some embodiments, the amount of SiO2 in the glass composition may be greater than approximately 68 mol%, greater than approximately 69 mol%, or even greater than approximately 70 mol%. In some other embodiments, the amount of SiO2 in the glass composition may be greater than approximately 72 mol%, greater than approximately 73 mol%, or even greater than approximately 74 mol%. For example, in some embodiments, the glass composition may include from approximately 68 mol% to approximately 80 mol%, or even up to approximately 78 mol% of SiO2.In some other embodiments, the glass composition may include from approximately 69 mol% to approximately 80 mol%, or even up to approximately 78 mol%, of SiO2. In some other embodiments, the glass composition may include from approximately 70 mol% to approximately 80 mol%, or even up to approximately 78 mol%, of SiO2. In still other embodiments, the glass composition comprises SiO2 in an amount greater than or equal to 70 mol% and less than or equal to 78 mol%. In some embodiments, SiO2 may be present in the glass composition in an amount of approximately 72 mol% to approximately 78 mol%. In some other embodiments, SiO2 may be present in the glass composition in an amount of approximately 73 mol% to approximately 78 mol%. In other bnoi i η / ι ζπζ / β / υιλι modalities, SiO2 may be present in the glass composition in an amount of approximately 74 molar to approximately 78 molar.In other forms, SiO2 may be present in the glass composition in an amount of approximately 70 mol% to approximately 76 mol%. The glass compositions described herein may additionally include Al₂O₃. Al₂O₃, in conjunction with the alkali oxides present in the glass compositions, such as Na₂O or similar, enhances the glass's susceptibility to ion-exchange strengthening. In the embodiments described herein, Al₂O₃ is present in the glass compositions at X mol%, while the alkali oxides are present in the glass composition at Y mol%. The Y:X ratio in the glass compositions described herein is greater than 1 to facilitate the aforementioned susceptibility to ion-exchange strengthening. Specifically, the diffusion coefficient or diffusivity D of the glass composition refers to the rate at which alkali ions penetrate the glass surface during ion exchange. Glasses with a Y:X ratio greater than approximately 0...Glasses with a Y:X ratio of 0.9, or even higher than approximately 1, have a higher diffusivity than glasses with a Y:X ratio less than 0.9. Glasses in which alkali ions have a higher diffusivity can achieve a greater layer depth during a given ion exchange time and temperature than glasses in which alkali ions have a lower diffusivity. Furthermore, the Y:X ratio increases, and the strain point, annealing point, and softening point of the glass decrease, making the glass easier to form. Furthermore, for a given ion exchange time and ion exchange temperature, it has been found that the compressive stresses induced in glasses having a Y:X ratio greater than approximately 0.9 and less than or equal to 2, are generally greater than those generated in glasses where the Y:X ratio is less than 0.9 or greater than 2.Therefore, in some embodiments, the Y:X ratio is greater than 0.9 or even greater than 1. In some embodiments, the Y:X ratio is greater than 0.9 or even greater than 1, and less than or equal to approximately 2. In other embodiments, the Y:X ratio may be greater than or equal to approximately 1.3 and less than or equal to approximately 2.0 to maximize the amount of compressive stress induced in the glass for a given ion exchange time and ion exchange temperature. However, if the amount of Al₂O₃ in the glass composition is too high, the resistance of the glass composition to acid attack decreases. Therefore, the glass compositions described herein generally include Al₂O₃ in an amount greater than or equal to approximately 2 mol% and less than or equal to approximately 10 mol%. In some embodiments, the amount of Al₂O₃ in the glass composition is greater than or equal to approximately 4 mol% and less than or equal to approximately 8 mol%. In some other embodiments, the amount of bnoi 1 η / ι ζπζ / β / υιλι The amount of Al₂O₃ in the glass composition is greater than or equal to approximately 5 mol%, up to less than or equal to approximately 7 mol%. In some other embodiments, the amount of Al₂O₃ in the glass composition is greater than or equal to approximately 6 mol%, up to less than or equal to approximately 8 mol%. In still other embodiments, the amount of Al₂O₃ in the glass composition is greater than or equal to approximately 5 mol%, up to less than or equal to approximately 6 mol%. Glass compositions also include one or more alkali oxides, such as Na₂O and / or K₂O. Alkali oxides facilitate ion exchange within the glass composition and thus facilitate chemical strengthening of the glass. The alkali oxide may include one or more of Na₂O and K₂O. Alkali oxides are generally present in the glass composition at a total concentration of Y molar percent. In some embodiments described herein, Y may be greater than approximately 2 molar percent and less than or equal to approximately 18 molar percent. In some other embodiments, Y may be greater than approximately 8 molar percent, greater than approximately 9 molar percent, greater than approximately 10 molar percent, or even greater than approximately 11 molar percent. For example, in some embodiments described herein, Y is greater than or equal to approximately 8 molar percent and less than or equal to approximately 18 molar percent.In other modalities, Y can be greater than or equal to approximately 9% molar and less than or equal to approximately 14% molar. The ion-exchange capacity of the glass composition bnoi 1 η / ι ζπζ / β / υιλι is imparted primarily to the glass composition by the amount of alkali oxide NazO initially present in the glass composition before ion exchange. Accordingly, in the embodiments of the glass compositions described herein, the alkali oxide present in the glass composition includes at least NazO. Specifically, to achieve the desired compressive strength and layer depth in the glass composition after ion-exchange strengthening, the glass compositions include NazO in an amount of approximately 2 mol% to approximately 15 mol%, based on the molecular weight of the glass composition. In some embodiments, the glass composition includes at least approximately 8 mol% NazO, based on the molecular weight of the glass composition.For example, the concentration of NazO may be greater than 9 mol%, greater than 10 mol%, or even greater than 11 mol%. In some embodiments, the concentration of NazO may be greater than or equal to 9 mol%, or even greater than or equal to 10 mol%. For example, in some embodiments, the glass composition may include NazO in an amount greater than or equal to approximately 9 mol% and less than or equal to approximately 15 mol%, or even greater than or equal to approximately 9 mol% and less than or equal to 13 mol%. As mentioned above, the alkali oxide in the glass composition may also include K₂O. The amount of K₂O present in the glass composition is also related to the ion exchange capacity of the glass composition. Specifically, as the amount of K₂O present in the glass composition increases, the compressive strength obtainable through ion exchange decreases as a result of the exchange of potassium and sodium ions. Therefore, it is desirable to limit the amount of K₂O present in the glass composition. In some embodiments, the amount of K₂O is greater than or equal to 0 mol% and less than or equal to 3 mol%. In some embodiments, the amount of K₂O is less than or equal to 2 mol% or even less than or equal to 1.0 mol%. In embodiments where the glass composition includes K₂O, the K₂O may be present at a concentration greater than or equal to approximately 0.0.01 mol%, and less than or equal to approximately 3.0 mol%, or even greater than or equal to approximately 0.01 mol% and less than or equal to approximately 2.0 mol%. In some embodiments, the amount of K₂O present in the glass composition is greater than or equal to approximately 0.01 mol%, and less than or equal to approximately 1.0 mol%. Therefore, it should be understood that the presence of K₂O in the glass composition is not required. However, when K₂O is included in the glass composition, the amount of K₂O is generally less than approximately 3 mol%, based on the molecular weight of the glass composition. Alkaline earth oxides may be present in the composition to improve the melting capacity of the glass materials in the batch and increase the chemical durability of the glass composition. In the glass compositions described herein, the total molar percentage of alkaline earth oxides present is generally less than the total molar percentage of alkali oxides present in the glass compositions, to improve the ion exchange capacity of the glass composition. In the embodiments described herein, the glass compositions generally include from approximately 3 mol% to approximately 13 mol% of alkaline earth oxide. In some of these embodiments, the amount of alkaline earth oxide in the glass composition may be from approximately 4 mol% to approximately 8 mol%, or even from approximately 4 mol% to approximately 7 mol%. The alkaline earth oxide in the glass composition may include MgO, CaO, SrO, BaO, or combinations thereof. In some embodiments, the alkaline earth oxide includes MgO, CaO, or combinations thereof. For example, in the embodiments described herein, the alkaline earth oxide includes MgO. The MgO is present in the glass composition in an amount greater than or equal to approximately 3 mol% and less than or equal to approximately 8 mol% MgO. In some embodiments, the MgO may be present in the glass composition in an amount greater than or equal to approximately 3 mol% and less than or equal to approximately 7 mol%, or even greater than or equal to 4 mol% and less than or equal to approximately 7 mol%, depending on the molecular weight of the glass composition. In some embodiments, the alkaline earth oxide may additionally include CaO. In these embodiments, CaO is present in the glass composition in an amount ranging from approximately 0 mol% to less than or equal to 6 mol%, depending on the molecular weight of the glass composition. For example, the amount of CaO present in the glass composition may be less than or equal to 5 mol%, less than or equal to 4 mol%, less than or equal to 3 mol%, or even less than or equal to 2 mol%. In some of these embodiments, CaO may be present in the glass composition in an amount greater than or equal to approximately 0.1 mol% and less than or equal to approximately 1.0 mol%. For example, CaO may be present in the glass composition in an amount greater than or equal to approximately 0.2 mol% and less than or equal to approximately 0.7 mol%, or even in an amount greater than or equal to approximately 0.3% molar and less than or equal to approximately 0.6% molar. In the forms described herein, the glass compositions are generally rich in MgO (i.e., the concentration of MgO in the glass composition is greater than the concentration of the other alkaline earth oxides in the glass composition, including, but not limited to, CaO). Forming the glass composition in such a way that it is rich in MgO improves the hydrolytic strength of the resulting glass, particularly after ion-exchange strengthening. Furthermore, glass compositions that are rich in MgO generally exhibit improved ion-exchange performance compared to glass compositions that are rich in other alkaline earth oxides. Specifically, glasses formed from MgO-rich glass compositions generally have higher diffusivity than glass compositions that are rich in other alkaline earth oxides, such as CaO.The greater diffusivity allows for the formation of a deeper layer within the glass. Glass compositions rich in MgO also allow for a higher compressive strength at the glass surface compared to compositions rich in other alkaline earth oxides, such as CaO. Furthermore, it is generally understood that as the ion exchange process progresses and alkali ions penetrate deeper into the glass, the maximum compressive strength achieved at the glass surface may decrease over time. However, glasses formed from MgO-rich compositions exhibit less of a reduction in compressive strength than glasses formed from CaO-rich or other alkaline earth oxide-rich compositions (i.e., MgO-poor glasses).In this way, glass compositions rich in MgO allow obtaining glasses that have greater compressive strength on the surface and greater layer depth than glasses that are rich in other alkaline earth oxides. To fully realize the benefits of MgO in the glass compositions described herein, it has been determined that the ratio of the CaO concentration to the sum of the CaO and MgO concentrations in molar percent (i.e., (CaO / (CaO+MgO)) must be minimized. Specifically, it has been determined that (CaO / (CaO+MgO)) must be less than or equal to 0.5. In some embodiments, (CaO / (CaO+MgO)) is less than or equal to 0.3, or even less than or equal to 0.2. In some other embodiments, (CaO / (CaO+MgO)) may even be less than or equal to 0.1. Boron oxide (B₂O₃) is a fluxing material that can be added to glass compositions to reduce viscosity at a given temperature (e.g., strain, annealing, and softening temperatures), thereby improving the formability of the glass. However, the addition of boron has been found to significantly decrease the diffusivity of sodium and potassium ions in the glass composition, which in turn adversely impacts the ion exchange performance of the resulting glass. In particular, the addition of boron has been found to significantly increase the time required to achieve a given layer depth compared to boron-free glass compositions. Consequently, in some embodiments described herein, the amount of boron added to the glass composition is minimized to improve its ion exchange performance. For example, it has been determined that the impact of boron on the ion exchange performance of a glass composition can be mitigated by controlling the ratio of the B₂O₃ concentration to the difference between the total concentration of the alkali oxides (i.e., R₂O, where R is the alkali metal) and alumina (i.e., B₂O₃ (molar %) / (R₂O (molar %) Al₂O₃ (molar %)). In particular, it has been determined that when the B₂O₃ / (R₂O-Al₂O₃) ratio is greater than or equal to approximately 0, and less than approximately 0.3, or even less than approximately 0.2, the diffusivity of the alkali oxides in the glass compositions is not reduced, and therefore the ion exchange performance of the glass composition is maintained. Consequently, in some embodiments, the ratio B2O3 / (R2O-Al2O3) is greater than 0 and less than or equal to 0.3. In some of these forms, the ratio B2O3 / (R2O-Al2O3) is greater than 0 and less than or equal to 0.2.In some embodiments, the B2O3 / (R2O-Al2O3) ratio is greater than 0 and less than or equal to 0.15, or even less than or equal to 0.1. In some other embodiments, the B2O3 / (R2O-Al2O3) ratio may be greater than 0 and less than or equal to 0.05. By keeping the B2O3 / (R2O-Al2O3) ratio less than or equal to 0.3, or even less than or equal to 0.2, B2O3 can be included to lower the strain point, annealing point, and softening point of the glass composition, without the B2O3 having an adverse impact on the ion exchange performance of the glass. In the embodiments described herein, the concentration of B2O3 in the glass composition is generally less than or equal to approximately 4 mol%, less than or equal to approximately 3 mol%, less than or equal to approximately 2 mol%, or even less than or equal to 1 mol%. For example, in embodiments where B2O3 is present in the glass composition, the concentration of B2O3 may be greater than approximately 0.01 mol% and less than or equal to 4 mol%. In some of these embodiments, the concentration of B2O3 may be greater than approximately 0.01 mol% and less than or equal to 3 mol%. In some embodiments, B2O3 may be present in an amount greater than or equal to approximately 0.01 mol% and less than or equal to 2 mol%, or even less than or equal to 1.5 mol%.Alternatively, B2O3 may be present in an amount greater than or equal to approximately 1 mol% and less than or equal to 4 mol%, greater than or equal to approximately 1 mol% and less than or equal to 3 mol%, or even greater than or equal to approximately 1 mol% and less than or equal to 2 mol%. In some of these forms, the concentration of B2O3 may be greater than or equal to approximately 0.1 mol% and less than or equal to 1.0 mol%. Although in some formulations the concentration of B2O3 in the glass composition is minimized to improve glass forming properties without compromising ion exchange performance, in others the glass compositions are free of boron and boron compounds such as B2O3. Specifically, it has been determined that forming glass compositions without boron or boron compounds improves the ion exchangeability of the glass compositions, reducing the processing time and / or temperature required to achieve a specific compressive strength and / or layer depth. In some embodiments of the glass compositions described herein, the glass compositions are free of phosphorus and phosphorus-containing compounds, including but not limited to P2O5. Specifically, it has been determined that the formulation of the glass composition without phosphorus or phosphorus compounds increases the chemical durability of the glass composition. In addition to SiO2, Al2O3, alkali oxides, and alkaline earth oxides, the glass compositions described herein may optionally comprise one or more clarifying agents, such as, for example, SnO2, As2O3, and / or IO3 (of NaCl or similar). When a clarifying agent is present in the glass composition, it may be present in an amount less than or equal to approximately 1 mol%, or even less than or equal to approximately 0.4 mol%. For example, in some embodiments, the glass composition may include SnO2 as a clarifying agent. In these embodiments, the SnO2 may be present in the glass composition in an amount greater than approximately 0 mol% and less than or equal to approximately 1 mol%, or even in an amount greater than or equal to approximately 0.01 mol% and less than or equal to approximately 0.30 mol%. Furthermore, the glass compositions described herein may comprise one or more additional metal oxides to further enhance the chemical durability of the glass composition. For example, the glass composition may additionally include ZnO, TiO2, or ZrO2, each of which further enhances the resistance of the glass composition to chemical attack. In these embodiments, the additional metal oxide may be present in an amount greater than or equal to approximately 0 mol% and less than or equal to approximately 2 mol%. For example, when the additional metal oxide is ZnO, the ZnO may be present in an amount greater than or equal to 1 mol% and less than or equal to approximately 2 mol%. When the additional metal oxide is ZrO2 or TiO2, the ZrO2 or TiO2 may be present in an amount less than or equal to approximately 1 mol%. As mentioned above, the presence of alkali oxides in the glass composition facilitates the chemical strengthening of the glass through ion exchange. Specifically, alkali ions, such as potassium ions, sodium ions, and the like, are sufficiently mobile in glass to facilitate ion exchange. In some embodiments, the glass composition is susceptible to ion exchange to form a compressive stress layer with a layer depth greater than or equal to 10 pm. In some embodiments, the layer depth may be greater than or equal to approximately 25 pm, or even greater than or equal to approximately 50 pm. In some other embodiments, the layer depth may be greater than or equal to 75 pm, or even greater than or equal to 100 pm. In still other embodiments, the layer depth may be greater than or equal to 10 pm and less than or equal to approximately 100 pm.The associated surface compressive stress may be greater than or equal to approximately 250 MPa, greater than or equal to 300 MPa, or even greater than or equal to approximately 350 MPa, after treating the glass composition in a 100% molten KNO3 salt bath at a temperature of 350°C to 500°C, for a period of less than approximately 30 hours or even less than approximately 20 hours. bnoi 1 η / ι ζπζ / β / υιλι Glass articles formed from the glass compositions described herein may have a hydrolytic strength of HGB2 or even HGB1 according to ISO 719, and / or a hydrolytic strength of HGA1 or even HGA1 according to ISO 720 (as further described herein), in addition to having improved mechanical properties due to ion-exchange strengthening. In some embodiments described herein, the glass articles may have compressive stress layers extending from the surface to the glass article to a layer depth greater than or equal to 25 pm, or even greater than or equal to 35 pm. In some embodiments, the layer depth may be greater than or equal to 40 pm, or even greater than or equal to 50 pm. The surface compressive strength of the glass article may be greater than or equal to 250 MPa, greater than or equal to 350 MPa, or even greater than or equal to 400 MPa.The glass compositions described herein facilitate obtaining the aforementioned layer depths and surface compressive strengths more rapidly and / or at lower temperatures than conventional glass compositions, due to the increased alkali ion diffusivity of the glass compositions described above. For example, layer depths (i.e., greater than or equal to 25 pm) and compressive strengths (i.e., greater than or equal to 250 MPa) can be obtained by ion exchange of the glass article in a molten salt bath of 100% KNO3 (or a mixed salt bath of KNO3 and NaNO3) for a time less than or equal to 5 hours, or even less than or equal to 4.5 hours, at a temperature less than or equal to 500°C, or even less than or equal to 450°C.In some methods, the time required to achieve these layer depths and compressive strengths can be less than or equal to 4 hours, or even less than or equal to 3.5 hours. The temperature required to achieve these layer depths and compressive strengths can be less than or equal to 400°C, or even less than or equal to 350°C. These improved ion-exchange characteristics can be achieved when the glass composition has a threshold diffusivity greater than approximately 16 pm² / ha at a temperature less than or equal to 450°C, or even greater than or equal to 20 pm² / ha at a temperature less than or equal to 450°C. In some embodiments, the threshold diffusivity can be greater than or equal to approximately 25 pm² / ha at a temperature less than or equal to 450°C, or even 30 pm² / ha at a temperature less than or equal to 450°C. In some other embodiments, the threshold diffusivity can be greater than or equal to approximately 35 pm² / ha at a temperature less than or equal to 450°C, or even 40 pm² / ha at a temperature less than or equal to 450°C. In other modalities, the threshold diffusivity may be greater than or equal to approximately 45 pm2 / ha at a temperature less than or equal to 450°C, or even 50 pm2 / ha at a temperature less than or equal to 450°C. The glass compositions described herein, in general, may have a deformation point greater than or equal to approximately 525°C and less than or equal to approximately 650°C. The glasses may also have an annealing point greater than or equal to approximately bnoi i η / ι ζπζ / β / υιλι 560°C and less than or equal to approximately 725°C, and a softening point greater than or equal to approximately 750°C and less than or equal to approximately 960°C. In the modalities described herein, the glass compositions have a lower CTE of approximately 70x10'7K'1 or even lower than approximately 60x10'7K'1. These lower CTE values ​​improve the survival of the glass under thermal cycling or thermal stress conditions, compared to glass compositions with higher CTEs. Furthermore, as stated above, glass compositions are chemically durable and resistant to degradation, as determined by DIN 12116, ISO 695 and ISO 720. Specifically, DIN 12116 is a measure of glass's resistance to disintegration when placed in an acidic solution. Briefly, DIN 12116 uses a polished glass sample of known surface area, which is weighed and then placed in contact with a proportional amount of boiling 6M hydrochloric acid for 6 hours. Afterward, the sample is removed from the solution, dried, and reweighed. The mass of glass lost during exposure to the acid solution is a measure of the sample's acid durability; smaller numbers indicate greater durability. Test results are reported in units of average mass per unit area, specifically mg / dm². bnoi i η / ι ζπζ / ε / υιλι The DIN 12116 standard is divided into individual classes. Class S1 indicates weight loss of up to 0.7 mg / dm2, class S2 indicates weight loss from 0.7 mg / dm2 to 1.5 mg / dm2; class S3 indicates weight loss from 1.5 mg / dm2 to 15 mg / dm2; and class S4 indicates weight loss of more than 15 mg / dm2. ISO 695 is a measure of glass's resistance to decomposition when placed in a basic solution. Briefly, ISO 695 uses a polished glass sample that is weighed and then placed in a boiling solution of 1M NaOH + 0.5M Na₂CO₃ for 3 hours. Afterward, the sample is removed from the solution, dried, and reweighed. The mass of glass lost during exposure to the basic solution is a measure of durability based on the sample; smaller numbers indicate greater durability. As with DIN 12116, ISO 695 results are reported in units of mass per unit area, specifically mg / dm². ISO 695 is divided into individual classes. Class A1 indicates weight loss up to 75 mg / dm²; Class A2 indicates weight loss from 75 mg / dm² to 175 mg / dm²; and class A3 indicates weight loss greater than 175 mg / dm2. ISO 720 is a measure of glass's resistance to degradation in CO2-free purified water. Briefly, the ISO 720 protocol uses crushed glass grains that are contacted with CO2-free purified water under autoclave conditions (121°C, 2 atm) for 30 minutes. The solution is then titrated colometrically with dilute HCl to neutral pH. The amount of HCl required to titrate to neutral is then converted to equivalents of Na₂O₂ extracted from the glass and reported in pg of Na₂O₂ per weight of glass; lower values ​​indicate greater durability. ISO 720 is divided into individual types.Type HGA1 is indicative of up to 62 pg NazO equivalents extracted per gram of glass tested; type HGA2 is indicative of more than 62 pg and up to 527 pg NazO equivalents extracted per gram of glass tested; and type HGA3 is indicative of more than 527 pg and up to 930 pg NazO equivalents extracted per gram of glass tested. ISO 719 is a measure of glass's resistance to degradation in CO2-free purified water. Briefly, the ISO 719 protocol uses crushed glass grains that are contacted with CO2-free purified water at 98°C and 1 atmosphere for 30 minutes. The solution is then colorimetrically titrated with dilute HCl to neutral pH. The amount of HCl required to reach neutral is then converted to equivalents of NaZO extracted from the glass and reported in pg of NaZO per weight of glass; lower values ​​indicate greater durability. ISO 719 is divided into individual types.Type HGB1 is indicative of up to 31 pg Na₂O equivalents; type HGB2 is indicative of more than 31 pg and up to 62 pg Na₂O equivalents; type HGB3 is indicative of more than 62 pg and up to 264 pg Na₂O equivalents; type HGB4 is indicative of more than 264 pg and up to 620 pg Na₂O equivalents; and type HGB5 is indicative of more than 620 pg and up to 1085 pg Na₂O equivalents. The glass compositions described herein have an ISO 719 hydrolytic resistance of type HGB2 or better; some embodiments have a hydrolytic resistance of type HGB1. The glass compositions described herein have an acid resistance of at least class S3 according to DIN 12116, both before and after ion-exchange strengthening; some embodiments have an acid resistance of at least class S2 or even class S1 after ion-exchange strengthening. In some other embodiments, the glass compositions may have an acid resistance of at least class S2, both before and after ion-exchange strengthening; some embodiments have an acid resistance of class S1 after ion-exchange strengthening. Furthermore, the glass compositions described herein have a base resistance according to ISO 695 of at least class A2, both before and after ion-exchange strengthening; some embodiments have a base resistance of at least class A1 after ion-exchange strengthening.The glass compositions described herein also have HGA2 hydrolytic strength according to ISO 720, both before and after ion-exchange strengthening; some embodiments have HGA1 hydrolytic strength after ion-exchange strengthening, and some other embodiments have HGA1 hydrolytic strength both before and after ion-exchange strengthening. The glass compositions described herein have HGB2 or better ISO 719 hydrolytic strength; some embodiments have HGB1 hydrolytic strength.It should be understood that, when referring to the classifications mentioned above according to DIN 12116, ISO 695, ISO 720, and ISO 719, a glass composition or glass article having at least one specified classification means that the performance of the glass composition is as good as or better than that of the specified classification. For example, a glass article with a DIN 12116 acid resistance of at least class S2 may have a DIN 12116 classification of S1 or S2. The glass compositions described herein are formed by mixing a batch of glass raw materials (e.g., powders of SiO2, Al2O3, alkali oxides, alkaline earth oxides, and the like) such that the batch of glass raw materials has the desired composition. The batch of glass raw materials is then heated to form a molten glass composition, which is subsequently cooled and solidified to form the glass composition. During solidification (i.e., when the glass composition is plastically deformable), the glass composition can be shaped using standard forming techniques to give the final desired shape. Alternatively, the glass article can be formed from a supply form, such as a sheet, tube, or the like, for subsequent reheating and shaping. The glass compositions described herein can be formed into glass articles of various shapes, such as sheets, tubes, or the like. However, given the chemical durability of the glass composition, the compositions described herein are particularly suitable for use in the formation of glass articles used as pharmaceutical packaging or containers for pharmaceutical compositions, such as liquids, powders, and the like. For example, the glass compositions described herein can be used to form glass containers of various shapes, including, but not limited to, Vacutainers®, cartridges, syringes, ampoules, bottles, flasks, jars, tubes, beakers, vials, or the like.Furthermore, the ability to chemically strengthen glass compositions through ion exchange can be used to improve the mechanical durability of these pharmaceutical packaging glass articles formed from the glass composition. Therefore, it should be understood that, in at least one embodiment, glass compositions are incorporated into pharmaceutical packaging to improve the chemical and / or mechanical durability of the pharmaceutical packaging. bnoi i η / ι ζπζ / β / υιλι EXAMPLES The types of glass compositions described herein will be made clearer by means of the examples that follow. EXAMPLE 1 Six exemplary glass compositions of the invention (AF compositions) were prepared. The specific compositions of each exemplary glass composition are indicated below in Table 1. Multiple samples of each exemplary glass composition were produced. A series of samples of each composition were subjected to ion exchange in a 100% KNO₃ molten salt bath at a temperature of 450 °C for at least 5 hours to induce a compressive layer on the sample surface. The compressive layer had a surface compressive strength of at least 500 MPa and a layer depth of at least 45 pm. The chemical durability of each sample glass composition was then determined using DIN 12116, ISO 695, and ISO 720, as previously described. Specifically, non-ion-exchange test samples of each sample glass composition were analyzed according to one of these standards: DIN 12116, ISO 695, or ISO 720, to determine the acid resistance, base resistance, or hydrolytic resistance of the sample, respectively. The hydrolytic resistance of the ion-exchange samples of each sample composition was determined according to ISO 720.To determine the hydrolytic strength of the ion-exchange samples, the glass was crushed to the grain size required by ISO 720, subjected to ion exchange in a 100% KNO3 molten salt bath at a temperature of 450 °C for at least 5 hours to induce a compressive stress layer on the individual glass grains, and then tested according to ISO 720. The average results of all samples are shown below in Table 1. As shown in Table 1, all sample AF glass compositions exhibited a glass mass loss of less than 5 mg / dm² and greater than 1 mg / dm² after testing according to DIN 12116, with sample E glass composition having the lowest glass mass loss at 1.2 mg / dm². Consequently, each sample glass composition was classified as at least class S3 according to DIN 12116, and sample E glass composition was classified as class S2. Based on these results, it is believed that the acid resistance of the glass samples improves with increasing SiO₂ content. Furthermore, all exemplary glass compositions AF showed a glass mass loss of less than 80 mg / dm² after testing according to ISO 695, with exemplary glass composition A having the lowest glass mass loss at 60 mg / dm². Consequently, each exemplary glass composition was classified as at least Class A2 according to ISO 695, and exemplary glass compositions A, B, D, and F were classified as Class A1. In general, compositions with a higher silica content exhibited lower base strength, and compositions with a higher alkali / alkaline earth content exhibited higher base strength. Table 1 also shows that non-ion-exchanged test samples of all AF exemplary glass compositions exhibited at least type HGA2 hydrolytic resistance after testing according to ISO 720, while CF exemplary glass compositions exhibited type HGA1 hydrolytic resistance. The hydrolytic resistance of CF exemplary glass compositions is believed to be due to the higher amounts of SiO2 and lower amounts of Na2O in these glass compositions compared to A and B exemplary glass compositions. Furthermore, the ion-exchanged test samples of the exemplary glass compositions BF showed lower amounts of Na2O per gram of glass than the non-ion-exchanged test samples of the same exemplary glass compositions, after testing according to ISO 720. bnoi i η / ι ζπζ / β / υιλι TABLE 1 Composition and properties of exemplary glass compositions bnoi i η / ι ζπζ / β / υιλι A Composition in molar % BCDEF SiO2 70.8 72.8 74.8 76.8 76.8 77.4 AI2O3 7.5 7 6.5 6 6 7 Na2O 13.7 12.7 11.7 10.7 11.6 10 K2O 1 1 1 1 0.1 0.1 MgO 6.3 5.8 5.3 4.8 4.8 4.8 CaO 0.5 0.5 0.5 0.5 0.5 0.5 SnO2 0.2 0.2 0.2 0.2 0.2 0.2 DIN 12116 3.2 2.0 1.7 1.6 1.2 1.7 (mg / dm2) classification S3 S3 S3 S3 S2 S3 ISO 695 60.7 65.4 77.9 71.5 76.5 62.4 (mg / dm2) classification A1 A1 A2 A1 A2 A1 ISO 720 100.7 87.0 54.8 57.5 50.7 37.7 (pg Na2O / g glass) classification HGA2 HGA2 HGA1 HGA1 HGA1 HGA1 ISO 720 (with 60.3 51.9 39.0 30.1 32.9 23.3 IX) (pg Na2O / g glass) classification HGA1 HGA1 HGA1 HGA1 HGA1 HGA1 EXAMPLE 2 Three exemplary glass compositions of the invention (compositions G1) and three comparative glass compositions (compositions 1-3) were prepared. The alkali-to-alumina oxide ratio (i.e., Y:X) was varied in each composition to evaluate the effect of this ratio on various properties of the molten glass mixture and the resulting glass. The specific compositions of each exemplary glass composition of the invention and the comparative glass compositions are listed in Table 2. The strain point, annealing point, and softening point of the molten mixtures formed from each of the glass compositions were determined and are listed in Table 2. In addition, the coefficient of thermal expansion (CTE), density, and coefficient of optical stress (SOC) of the resulting glasses were also determined and are listed in Table 2.The hydrolytic strength of glass samples formed from each exemplary glass composition of the invention and each comparative glass composition was determined according to ISO 720, both before and after ion exchange in a 100% KNO₃ molten salt bath at 450°C for 5 hours. In the samples subjected to ion exchange, the compressive strength was determined using a fundamental stress measuring (FSM) instrument, with the compressive strength value based on the measured optical stress coefficient (SOC). The FSM instrument couples light into and out of the birefringent glass surface. The measured birefringence is then related to the stress by means of a material constant, the optical or photoelastic stress coefficient (SOC or PEC), and two parameters are obtained: the maximum surface compressive strength (CS) and the depth of layer exchange (DOL).The diffusivity of alkali ions in the glass and the change in stress by the square root of time were also determined. The diffusivity (D) of the glass is calculated from the measured layer depth (DOL) and the ion exchange time (t) according to the relationship: DOL = -1.4 * bnoi 1 η / i ζπζ / β / υιλι ^(4 * D * t). The diffusivity increases with temperature according to an Arrhenius relationship and is therefore reported as a temperature-specific value. bnoi i η / ι ρπζ / ε / υιλι TABLE 2 Properties of glass as a function of the alkali to alumina ratio Composition, molar % GH 1 1 2 3 SiO2 76.965 76.852 76.962 76.919 76.960 77.156 Al2O3 5.943 6.974 7.958 8.950 4.977 3.997 Na2O 11.427 10.473 9.451 8.468 12.393 13.277 K2O 0.101 0.100 0.102 0.105 0.100 0.100 MgO 4.842 4.878 4.802 4.836 4.852 4.757 CaO 0.474 0.478 0.481 0.480 0.468 0.462 SnO2 0.198 0.195 0.197 0.197 0.196 0.196 Strain (°C) 578 616 654 683 548 518 Annealing (°C) 633 674 716 745 600 567 Softening (°C) 892 946 1003 1042 846 798 Expansion (107 K 1) 67.3 64.3 59.3 55.1 71.8 74.6 Density (g / cm3) 2.388 2.384 2.381 2.382 2.392 2.396 SOC (nm / mm / Mpa) 3.127 3.181 3.195 3.232 3.066 3.038 ISO720 (non-IX) 88.4 60.9 47.3 38.4 117.1 208.1 ISO720 (IX 450°C5h) 25.3 26 20.5 17.8 57.5 102.5 R2O / AI2O3 1.940 1.516 1.200 0.958 2.510 3.347 CS@t=0 (MPa) 708 743 738 655 623 502 CS / \t (MPa / h1 / 2) -35 -24 -14 -7 -44 -37 D (pm2 / h) 52.0 53.2 50.3 45.1 51.1 52.4 The data in Table 2 indicate that the alkali-to-alumina ratio The Y:X ratio affects the melting behavior, hydrolytic strength, and compressive strength obtained through ion-exchange strengthening. Specifically, Figure 1 graphically represents the strain point, annealing point, and softening point as a function of the Y:X ratio for the glass compositions in Table 2. Figure 1 shows that as the Y:X ratio decreases below 0.9, the strain point, annealing point, and softening point of the glass increase rapidly. Therefore, to obtain a glass that is easily fusible and formable, the Y:X ratio should be greater than or equal to 0.9, or even greater than or equal to 1. Furthermore, the data in Table 2 indicate that the diffusivity of glass compositions generally decreases with the Y:X ratio. Therefore, to obtain glasses that can exchange ions quickly to reduce processing times (and costs), the Y:X ratio should be greater than or equal to 0.9, or even greater than or equal to 1. Furthermore, Figure 2 indicates that for a given ion exchange time and temperature, maximum compressive stresses are obtained when the Y:X ratio is greater than or equal to approximately 0.9, or even greater than or equal to approximately 1 and less than or equal to approximately 2, specifically greater than or equal to approximately 1.3 and less than or equal to approximately 2.0. Consequently, the maximum improvement in the load-bearing strength of the glass can be obtained when the Y:X ratio is greater than approximately 1 and less than or equal to approximately 2. It is generally understood that the maximum stress obtainable by ion exchange will decrease as the ion exchange time increases, as indicated by the rate of change of stress (i.e., the measured compressive stress divided by the square root of the ion exchange time).Figure 2 shows that, in general, the rate of change of stress decreases as the Y:X ratio decreases. Figure 3 graphically represents hydrolytic resistance (y-axis) as a function of the Y:X ratio (x-axis). As shown in Figure 3, the hydrolytic resistance of glasses generally improves as the Y:X ratio decreases. Based on the above, it should be understood that glasses with good melting behavior, superior ion exchange performance, and superior hydrolytic resistance can be obtained by keeping the Y:X ratio in the glass greater than or equal to approximately 0.9, or even greater than or equal to approximately 1, and less than or equal to approximately 2. EXAMPLE 3 Three exemplary glass compositions of the invention (compositions JL) and three comparative glass compositions (compositions 4-6) were prepared. The concentrations of MgO and CaO in the glass compositions were varied to produce both MgO-rich compositions (i.e., compositions JL and 4) and CaO-rich compositions (i.e., compositions 5-6). The relative amounts of MgO and CaO were also varied so that the glass compositions had different values ​​of the ratio (CaO / (CaO+MgO)). The specific compositions of each of the exemplary compositions of the invention and the comparative glass compositions are indicated below in Table 3. The properties of each composition were determined as described above in Example 2. bnoi i η / ι ζπζ / β / υιλι TABLE 3 Properties of glass as a function of CaO content Composition, molar % JKL 4 5 6 SiO2 76.99 77.10 77.10 77.01 76.97 77.12 AI2O3 5.98 5.97 5.96 5.96 5.97 5.98 Na2O 11.38 11.33 11.37 11.38 11.40 11.34 K2O 0.10 0.10 0.10 0.10 0.10 0.10 MgO 5.23 4.79 3.78 2.83 1.84 0.09 CaO 0.07 0.45 1.45 2.46 3.47 5.12 SnO2 0.20 0.19 0.19 0.19 0.19 0.19 Strain (°C) 585 579 568 562 566 561 Annealing (°C) 641 634 620 612 611 610 Softening (°C) 902 895 872 859 847 834 Expansion (10'7 K'1) 67.9 67.1 68.1 68.8 69.4 70.1 Density (g / cm3) 2.384 2.387 2.394 2.402 2.41 2.42 SOC nm / mm / MPa 3.12 3.08 3.04 3.06 3.04 3.01 ISO720 (non-IX) 83.2 83.9 86 86 88.7 96.9 ISO720 (IX 450°C-5h) 29.1 28.4 33.2 37.3 40.1 Fraction of RO as CaO 0.014 0.086 0.277 0.465 0.654 0.982 CS@t=O (MPa) 707 717 713 689 693 676 CS / \t (MPa / h1 / 2) -36 -37 -39 -38 -43 -44 D (pm2 / h) 57.2 50.8 40.2 31.4 26.4 20.7 Figure 4 graphically represents the diffusivity D of the compositions indicated in Table 3 as a function of the ratio (CaO / (CaO+MgO)). Specifically, Figure 4 indicates that as the ratio (CaO / (CaO+MgO)) increases, the diffusivity of the alkali ions in the resulting glass decreases, thus reducing the glass's ion exchange efficiency. This trend is supported by the data in Table 3 and Figure 5. Figure 5 graphically represents the maximum compressive strength and the rate of change of stress (y-axis) as a function of the ratio (CaO / (CaO+MgO)). Figure 5 indicates that as the ratio (CaO / (CaO+MgO)) increases, the maximum compressive strength obtainable for a given ion exchange temperature and time decreases. Figure 5 also indicates that as the ratio (CaO / (CaO+MgO)) increases, the rate of change of stress increases (i.e., it becomes more negative and less desirable). Therefore, based on the data in Table 3 and Figures 4 and 5, it should be understood that glasses with higher diffusivities can be produced by minimizing the ratio (CaO / (CaO+MgO)). It has been determined that glasses with suitable diffusivities can be produced when the ratio (CaO / (CaO+MgO)) is less than approximately 0.5. The diffusivity values ​​of the glass when the ratio (CaO / (CaO+MgO)) is less than approximately 0.5 decrease the ion exchange processing times required to obtain a given compressive strength and layer depth. Alternatively, glasses with higher diffusivities due to the ratio (CaO / (CaO+MgO)) can be used to obtain greater compressive strength and layer depth for a given ion exchange temperature and ion exchange time. Furthermore, the data in Table 3 also indicate that decreasing the ratio (CaO / (CaO+MgO)), by increasing the concentration of MgO, generally improves the resistance of glass to hydrolytic degradation, as measured according to ISO 720. EXAMPLE 4 Three exemplary glass compositions of the invention (compositions MO) and three comparative glass compositions (compositions 7-9) were prepared. The concentration of B₂O₃ in the glass compositions was varied from 0 mol% to approximately 4.6 mol%, such that the resulting glasses had different B₂Os / (R₂O₃Al₂O₃) ratios. The specific compositions of each of the exemplary compositions of the invention and the comparative glass compositions are indicated below in Table 4. The properties of each glass composition were determined as described above in Examples 2 and 3. bnoi 1 η / ι ζπζ / β / υιλι TABLE 4 Glass properties as a function of B2O3 content bnoi 1 η / ι ζπζ / β / υιλι Composition, molar % MNO 7 8 9 S¡02 76,860 76,778 76,396 74,780 73,843 72,782 AI2O3 5,964 5,948 5,919 5,793 5,720 5,867 B2O3 0,000 0,214 0.777 2.840 4.443 4.636 Na2O 11.486 11.408 11.294 11.036 10.580 11.099 K2O 0.101 0.100 0.100 0.098 0.088 0.098 MgO 4.849 4,827 4,801 4,754 4,645 4,817 CaO 0.492 0.480 0.475 0.463 0.453 0.465 SnO2 0.197 0.192 0.192 0.188 0.183 0.189 Strain (°C) . 579 575 572 560 552 548 Annealing (°C) 632 626 622 606 597 590 Softening (°C) 889 880 873 836 816 801 Expansion (10'7 K'1) 68.3 67.4 67.4 65.8 64.1 67.3 Density (g / cm3) 2.388 2.389 2.390 2.394 2.392 2.403 SOC (nm / mm / Mpa) 3.13 3.12 3.13 3.17 3.21 3.18 ISO720 (no-IX) 86.3 78.8 68.5 64.4 52.7 54.1 ISO720 (IX 450°C-5h) 32.2 30.1 26 24.7 22.6 26.7 B2O3 / (R2O-AI2O3) 0.000 0.038 0.142 0.532 0.898 0.870 CS@t=O (MPa) 703 714 722 701 686 734 CS / Vt (MPa / h1 / 2) -38 -38 -38 -33 -32 -39 D (pm2 / h) 51.7 43.8 38.6 22.9 16.6 15.6 Figure 6 graphically represents the diffusivity D (y-axis) of the glass compositions in Table 4 as a function of the ratio BzOa / (R2O-AbOs) (x-axis) for the glass compositions in Table 4. As shown in Figure 6, the diffusivity of alkali ions in glass generally decreases as the ratio 62()3 / (R2O-Al2O3) increases. Figure 7 graphically represents the hydrolytic resistance according to ISO 720 (y-axis) as a function of the B2O3 / (R2O-Al2O3) ratio (x-axis) for the glass compositions in Table 4. As shown in Figure 6, the hydrolytic resistance of the glass compositions generally improves as the B2O3 / (R2O-Al2O3) ratio increases. Based on Figures 6 and 7, it should be understood that minimizing the ratio 62()3 / (R2O-Al2O3) improves the diffusivity of alkali ions in the glass, thus enhancing the glass's ion exchange characteristics. Furthermore, increasing the ratio 62()3 / (R2O-Al2O3) also generally improves the glass's resistance to hydrolytic degradation. Additionally, it has been found that the glass's resistance to degradation in acidic solutions (measured according to DIN 12116) generally improves with decreasing B2O3 concentration. Therefore, it has been determined that maintaining the B2O3 / (R2O-Al2O3) ratio less than or equal to approximately 0.3 results in glass with improved hydrolytic and acid resistance, and also provides enhanced ion exchange characteristics. It should now be understood that the glass compositions described herein exhibit chemical durability and also mechanical durability after ion exchange. These properties make the glass compositions very suitable for use in various applications, including, but not limited to, pharmaceutical packaging materials. Based on the above, it should now be understood that several aspects of glass compositions, and glass articles formed from glass compositions, are described. According to the first aspect, a glass composition may include: SiO2 in a concentration greater than approximately 70 mol% and 1 mol% of alkali oxide. The alkali oxide may include NaO in an amount greater than approximately 8 mol%. The glass composition may be free of boron and boron compounds. Secondly, the glass composition of the first aspect includes SiO2 in an amount greater than or equal to approximately 72 mol% In a third aspect, the glass composition of the first or second aspect is free of phosphorus and phosphorus compounds. In a fourth aspect, the glass composition of any of the first to third aspects also includes X mol% of Al2O3, where the ratio Y:X is greater than 1. In a fifth aspect, the glass composition of the ratio Y:X in the fourth aspect is less than or equal to 2. In a sixth aspect, the glass composition of the amount of Al2O3 in the fourth or fifth aspect is greater than or equal to approximately 2 mol% and less than or equal to approximately 10 mol%. In a seventh aspect, the glass composition of any of the first through fifth aspects also includes from approximately 3 mol% to approximately 13 mol% of alkaline earth oxide. In an eighth aspect, the alkaline earth oxide of the seventh aspect includes MgO and CaO, the CaO is present in an amount greater than or equal to approximately 0.1 mol%, and less than or equal to approximately 1.0 mol%, and the ratio (CaO (% molar) / (CaO (% molar) + MgO (% molar)) is less than or equal to 0.5. bnoi 1 η / ι ζπζ / β / υιλι In a ninth aspect, a glass composition may include more than approximately 68 mol% SiOz; X mol% Al2O3; Y mol% alkali oxide; and B2O3. The alkali oxide may include Na2O in an amount greater than approximately 8 mol%. The ratio (B2O3 (mol%) / (Y mol% - X mol%)) may be greater than 0 and less than 0.3. In a tenth aspect, the glass composition of the ninth aspect includes SiO2 in an amount greater than or equal to approximately 72 mol% In an eleventh aspect, the glass composition of the ninth or tenth aspect includes B2O3 in an amount greater than or equal to approximately 0.01 mol% and less than or equal to approximately 4 mol%. In a twelfth aspect, the glass composition of any of the ninth to eleventh aspects, wherein the glass composition has a Y:X ratio greater than 1. In a thirteenth aspect, the Y:X ratio of the twelfth aspect is less than or equal to 2. A fourteenth aspect includes the glass composition of any of the ninth to thirteenth aspects, where X is greater than or equal to approximately 2 mol% and less than or equal to approximately 10 mol%. A fifteenth aspect includes the glass composition of any of the ninth to fourteenth aspects, wherein the glass composition is free of phosphorus and phosphorus compounds. A sixteenth aspect includes the glass composition of any of the ninth to fifteenth aspects, wherein the glass composition further comprises MgO and CaO, the CaO is present in an amount greater than or equal to approximately 0.1 mol% and less than or equal to approximately 1.0 mol%, and the ratio (CaO (molar %) / (CaO (molar %)+MgO (molar %))) is less than or equal to 0.5. In a seventeenth aspect, the glass article may have a hydrolytic resistance of type HGB1 according to ISO 719. The glass article may include more than approximately 8 mol% of NazO and less than approximately 4 mol% of B2O3. In an eighteenth aspect, the glass article of the seventeenth aspect further comprises X mol% of Al2O3 and Y mol% of alkali oxide, wherein the ratio (B2O3 (mol%) / (Y mol% - X mol%) is greater than 0 and less than 0.3. In a nineteenth aspect, the glass article of any seventeenth to eighteenth aspect further comprises a compressive stress layer having a surface compressive stress greater than or equal to approximately 250 MPa. A twentieth aspect includes the glass article of any of the seventeenth to nineteenth aspects, wherein the glass article has at least class S3 acid resistance according to DIN 12116. bnoi 1 η / ι ζπζ / β / υιλι A twenty-first aspect includes the glass article of any of the seventeenth to twentieth aspects, wherein the glass article has at least Class A2 base strength in accordance with ISO 695. A twenty-second aspect includes the glass article of any of the seventeenth to twenty-first aspects, wherein the glass article has a hydrolytic resistance of type HGA1 according to ISO 720. In a twenty-third aspect, a pharmaceutical glass container may contain: SiO2 in an amount greater than approximately 70 mol%; X mol% of Al2O3; and Y mol% of alkali oxide. The alkali oxide may contain Na2O in an amount greater than approximately 8 mol%. The ratio of the concentration of B2O3 (mol%) in the pharmaceutical glass container to (Y mol% - X mol%) may be less than 0.3. The pharmaceutical glass container may also have a hydrolytic resistance of type HGB1 in accordance with ISO 719. A twenty-fourth aspect includes the pharmaceutical glass container of the twenty-third aspect, wherein the amount of SiO2 is greater than or equal to 72 mol% and less than or equal to approximately 78 mol%. A twenty-fifth aspect includes the pharmaceutical glass container from the twenty-third to the twenty-fourth aspect, wherein X is greater than or equal to approximately 4 molar % and less than or equal to bnoi 1 η / ι ζπζ / β / υιλι approximately 8 molar %. A twenty-sixth aspect includes the pharmaceutical glass container from the twenty-third to the twenty-fifth aspect, where the ratio Y:X is greater than 1. A twenty-seventh aspect includes the pharmaceutical glass container from the twenty-third to the twenty-sixth aspect, where the Y:X ratio is less than 2. A twenty-eighth aspect includes the pharmaceutical glass container from the twenty-third to the twenty-seventh aspect, which further comprises from approximately 4 mol% to approximately 8 mol% of alkaline earth oxide. A twenty-ninth aspect includes the pharmaceutical glass container of the twenty-third to twenty-eighth aspects, which further comprises MgO and CaO, the CaO being present in an amount greater than or equal to approximately 0.2 mol% and less than or equal to approximately 0.7 mol%, and the ratio (CaO (molar %) / (CaO (molar %)+MgO (molar %))) is less than or equal to 0.5. A thirtieth aspect includes the pharmaceutical glass container from the twenty-third to the twenty-ninth aspect, where the pharmaceutical container has a hydrolytic resistance of type HGA1 according to ISO 720 In a thirty-first aspect, a glass composition may include from approximately 70 mol% to approximately 80 mol% SiOz; from approximately 3 mol% to approximately 13 mol% alkaline earth oxide; X mol% Al₂O₃; and Y mol% alkali oxide. The alkali oxide may include Na₂O in a greater amount of approximately 8 mol%. The Y:X ratio may be greater than 1, and the glass composition may be free of boron and boron compounds. In a thirty-second aspect, a glass composition may include: from approximately 72 mol% to approximately 78 mol% of SiO2; from approximately 4 mol% to approximately 8 mol% of alkaline earth oxide; X mol% of Al2O3; and Y mol% of alkali oxide. The amount of alkaline earth oxide may be greater than or equal to approximately 4 mol% and less than or equal to approximately 8 mol%. The alkali oxide may include Na2O in an amount greater than or equal to approximately 9 mol% and less than or equal to approximately 15 mol%. The ratio Y:X may be greater than 1. The glass composition may be free of boron and boron compounds. In a thirty-third aspect, a glass composition may include: from approximately 68 mol% to approximately 80 mol% of SiO2; from approximately 3 mol% to approximately 13 mol% of alkaline earth oxide; X mol% of Al2O3; and Y mol% of alkali oxide. The alkali oxide may include Na2O in an amount greater than approximately 8 mol%. The glass composition may also include B2O3. The ratio (B2O3 (mol%) / (Y mol% - X mol%)) may be greater than 0 and less than 0.3, and the ratio Y:X may be greater than 1. In a thirty-fourth aspect, a glass composition may include from approximately 70 mol% to approximately 80 mol% of SiO2; from approximately 3 mol% to approximately 13 mol% of alkaline earth oxide; X mol% of Al2O3; and Y mol% of alkali oxide. The alkaline earth oxide may include CaO in an amount greater than or equal to approximately 0.1 mol% and less than or equal to approximately 1.0 mol%. X may be greater than or equal to approximately 2 mol% and less than or equal to approximately 10 mol%. The alkali oxide may include from approximately 0.01 mol% to approximately 1.0 mol% of K2O. The ratio Y:X may be greater than 1. The glass composition may be free of boron and boron compounds. In a thirty-fifth aspect, a glass composition may include S1O2 in an amount greater than approximately 70 mol% and less than or equal to approximately 80 mol%; from approximately 3 mol% to approximately 13 mol% of alkaline earth oxide; X mol% of Al2O3; and Y mol% of alkali oxide. The alkali oxide may include Na2O in an amount greater than approximately 8 mol%. The ratio of the concentration of B2O3 (mol%) in the glass composition to (Y mol% - X mol%) may be less than 0.3. The ratio Y:X may be greater than 1. In a thirty-sixth aspect, the glass composition of any of the thirty-first to thirty-fifth aspects, wherein SiO2 is present in an amount less than or equal to 78 mol% A thirty-seventh aspect includes the glass composition of any of the thirty-first to thirty-sixth aspects, wherein the amount of alkaline earth oxide is greater than or equal to approximately 4 mol% and less than or equal to approximately 8 mol%. A thirty-eighth aspect includes the glass composition of any of the thirty-first to thirty-seventh aspects, wherein the alkaline earth oxide comprises MgO and CaO, and the ratio (CaO (molar %) / (CaO (molar %)+MgO (molar %))) is less than or equal to 0.5. A thirty-ninth aspect includes the glass composition of any of the thirty-first through thirty-eighth aspects, wherein the alkaline earth oxide comprises from approximately 0.1 mol% to less than, or equal to, approximately 1.0 mol% of CaO. A fortieth aspect includes the glass composition of any of the thirty-first to thirty-ninth aspects, wherein the alkaline earth oxide comprises from approximately 3 mol% to approximately 7 mol% of MgO. A forty-first aspect includes the glass composition of any of the thirty-first, thirty-second, or thirty-fourth aspect, wherein X is greater than or equal to approximately 2 mol% and less than or equal to approximately 10 mol%. A forty-second aspect includes the glass composition of any of the thirty-first to forty-first aspects, wherein the alkali oxide comprises an amount greater than or equal to approximately 9 mol% Na2O, and less than or equal to approximately 15 mol% Na2O. bnoi i η / ι ζπζ / β / υιλι A forty-third aspect includes the glass composition of any of the thirty-first to forty-second aspects, where the ratio Y:X is less than or equal to 2. A forty-fourth aspect includes the glass composition of any of the thirty-first to forty-third aspects, where the ratio Y:X is greater than or equal to 1.3 and less than or equal to 2.0. A forty-fifth aspect includes the glass composition of any of the thirty-first to forty-fourth aspects, wherein the alkali oxide further comprises K2O in an amount less than or equal to approximately 3 mol% A forty-sixth aspect includes the glass composition of any of the thirty-first through forty-fifth aspects, wherein the glass composition is free of phosphorus and phosphorus compounds. A forty-seventh aspect includes the glass composition of any of the thirty-first to forty-sixth aspects, wherein the alkali oxide comprises K2O in an amount greater than or equal to approximately 0.01 mol% and less than or equal to approximately 1.0 mol%. A forty-eighth aspect includes the glass composition of either the thirty-second or thirty-fourth aspect, wherein the amount of SiO2 is greater than or equal to approximately 70 mol% bnoi 1 η / ι ζπζ / β / υιλι A forty-ninth aspect includes the glass composition of either the thirty-second or thirty-fourth aspect, wherein the ratio (B2O3 (mol%) / (Y mol% - X mol%) is less than 0.2. A fiftieth aspect includes the glass composition of either the thirty-second or thirty-fourth aspect, wherein the amount of B2O3 is less than or equal to approximately 4.0 mol%. A fifty-first aspect includes the glass composition of the fiftieth aspect, wherein the amount of B2O3 is greater than or equal to approximately 0.01 mol%. A fifty-second aspect includes the glass composition of the thirty-fourth aspect, wherein the glass composition is free of boron and boron compounds. A fifty-third aspect includes the glass composition of any of the thirty-first to thirty-fourth aspects, wherein the concentration of SiO2 is greater than or equal to approximately 72 mol% A fifty-fourth aspect includes the glass composition of any of the thirty-first to fifty-third aspects, wherein the concentration of SiO2 is greater than or equal to approximately 73 mol% In a fifty-fifth aspect, the glass article is formed from the glass composition of any of the thirty-first through fifty-fourth aspects. A fifty-sixth aspect includes the glass article of the fifty-fifth aspect, wherein the glass article has a hydrolytic resistance of type HGB1 according to ISO 719. A fifty-seventh aspect includes the glass article of any of the fifty-fifth to fifty-sixth aspects, wherein the glass article has a hydrolytic strength of type HGA1 according to ISO 720 after ion exchange strengthening. A fifty-eighth aspect includes the glass article of any of the fifty-fifth to fifty-seventh aspects, wherein the glass article has a hydrolytic strength of type HGA1 according to ISO 720, before and after ion exchange strengthening. A fifty-ninth aspect includes the glass article of any of the fifty-fifth to fifty-eighth aspects, wherein the glass article has at least class S3 acid resistance according to DIN 12116. A sixtieth aspect includes the glass article of any of the fifty-fifth to fifty-ninth aspects, wherein the glass article has at least Class A2 base strength in accordance with ISO 695. A sixty-first aspect includes the glass article of any of the fifty-fifth to sixtieth aspects, wherein the glass article is a pharmaceutical container. A sixty-second aspect includes the glass article of bnoi i η / ι ζπζ / β / υιλι any of the fifty-fifth to sixty-first aspects, wherein the glass article is strengthened by means of ion exchange. A sixty-third aspect includes the glass article of any of the fifty-fifth to sixty-second aspects, wherein the glass article further has a compressive stress layer with a layer depth greater than or equal to 10 pm and a surface compressive stress greater than or equal to 250 MPa. In a sixty-fourth aspect, the glass article may have a hydrolytic resistance of type HGB1 according to ISO 719. The glass article may also have a threshold diffusivity greater than 16 pm2 / ha at a temperature less than or equal to 450°C. A sixty-fifth aspect includes the glass article of the sixty-fourth aspect, wherein the threshold diffusivity is greater than or equal to 20 pm2 / ha at a temperature less than or equal to 450°C. A sixty-sixth aspect includes the glass article of any of the sixty-third to sixty-fourth aspects, wherein the glass article has a hydrolytic strength of type HGA1 according to ISO 720 after ion exchange strengthening. A sixty-seventh aspect includes the glass article of any of the sixty-fourth to sixty-sixth aspects, which further comprises a compressive stress with a layer depth greater than 25 pm. A sixty-eighth aspect includes the glass article of the sixty-seventh aspect, where the layer depth is greater than 35 pm. A sixty-ninth aspect includes the glass article of any of the sixty-third to sixty-eighth aspects, wherein the glass article is strengthened by ion exchange, and the strengthening by ion exchange comprises treating the glass article in a molten salt bath for a time less than or equal to 5 hours, at a temperature less than or equal to 450°C. A seventieth aspect includes the glass article of any of the sixty-third to sixty-ninth aspects, which further comprises a surface compressive stress greater than or equal to 350 MPa. A seventy-first aspect includes the glass article of any of the sixty-third to seventieth aspects, wherein the surface compressive stress is greater than or equal to 400 MPa. A seventy-second aspect includes the glass article of any of the sixty-third to seventy-first aspects, wherein the glass article is strengthened by ion exchange, and the strengthening by ion exchange comprises treating the glass article in a molten salt bath for a time less than or equal to 5 hours, at a temperature less than or equal to 450°C. A seventy-second aspect includes the glass article of any of the sixty-third to seventy-second aspects, in bnoi i η / ι ζπζ / β / υιλι where the glass article is a pharmaceutical container. In a seventy-third aspect, the glass article may have hydrolytic resistance of type HGB1 according to ISO 719. The glass article may also have a compressive strength layer with a layer depth greater than 25 pm, and a surface compressive strength greater than or equal to 350 MPa. The glass article may be strengthened by ion exchange, and the ion exchange strengthening may include treating the glass article in a molten salt bath for a time less than or equal to 5 hours, at a temperature less than or equal to 450°C. A seventy-fourth aspect includes the glass article of the seventy-third aspect, wherein the glass article has a hydrolytic resistance of type HGA1 according to ISO 720 after ion exchange strengthening. A seventy-fifth aspect includes the glass article of any of the seventy-third to seventy-fourth aspects, wherein the glass article has a threshold diffusivity greater than 16 pm2 / ha and a temperature less than or equal to 450°C. A seventy-sixth aspect includes the glass article of any of the seventy-third to seventy-fifth aspects, wherein the threshold diffusivity is greater than or equal to 20 pm2 / ha at a temperature less than or equal to 450°C. A seventy-seventh aspect includes the glass article of bnoi i η / ι ζπζ / β / υιλι any of the seventy-third to seventy-sixth aspects, wherein the glass article is a pharmaceutical container. It will be evident to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the subject matter claimed. Thus, it is intended that this specification cover modifications and variations of the various embodiments described herein, provided that such modifications and variations are within the scope of the appended claims and their equivalents.

Claims

NOVELTY OF THE INVENTION CLAIMS 1. A pharmaceutical packaging glass having a glass composition comprising: from approximately 74 mol% to approximately 80 mol% of SiO2; alkaline earth oxide comprising MgO and CaO and a ratio (CaO(mol%) / (CaO(mol%)+MgO(mol%))) is greater than 0 and less than or equal to 0.5 and the CaO is from 0.1 to approximately 1.0 mol%; X mol% of Al2O3, wherein X is from approximately 4 to approximately 8; and Y molar% of alkali oxide comprising non-zero amounts of Na2O and K2O, wherein Y is greater than approximately 8 molar%, a ratio Y:X is greater than or equal to 1, and a ratio of a concentration of B2O3 (mol%) to (Y molar%-X mol%) is less than or equal to 0.

3.

2. The pharmaceutical packaging glass according to claim 1, further characterized in that the alkaline earth oxide comprises from approximately 3 mol% to approximately 7 mol% of MgO.

3. The pharmaceutical packaging glass according to claim 1, further characterized in that a Y:X ratio is less than or equal to 2.

4. The pharmaceutical packaging glass according to claim 1, further characterized in that the alkali oxide comprises Na2O in an amount of at least 8% molar.

5. The glass for pharmaceutical packaging according to claim 1, further characterized in that the glass composition is free of boron or boron compounds.

6. The pharmaceutical packaging glass according to claim 1, further characterized in that the glass is ion exchange reinforced and has a compressive stress layer with a layer depth greater than or equal to 10 pm and a compressive stress surface greater than or equal to 250 MPa.

7. The pharmaceutical packaging glass according to claim 1, further characterized in that the glass has a hydrolytic resistance type HGB1 according to ISO 719.

8. A pharmaceutical packaging glass having a glass composition comprising: from approximately 70 mol% to approximately 80 mol% SiO2; from approximately 4 mol% to approximately 8 mol% alkaline earth oxide comprising MgO and CaO, wherein a concentration of CaO is from 0.1 mol% to 1.0 mol% and a ratio (CaO(mol%) / (CaO(mol%)+MgO(mol%))) is greater than 0 and less than or equal to 0.5; X mol% Al2O3; and Y molar percentage of alkali oxide comprising non-zero amounts of Na2O and K2O, wherein Y is greater than 9 molar percentage, a concentration of Na2O is from 2 molar percentage to 15 molar percentage, a ratio Y:X is greater than or equal to 1 and less than or equal to 2, and a ratio of a concentration of B2O3 (mol%) to (Y molar percentage - X mol%) is less than or equal to 0.

3.

9. The pharmaceutical packaging glass according to claim 8, further characterized in that the alkaline earth oxide comprises from approximately 3 mol% to approximately 7 mol% MgO.

10. The pharmaceutical packaging glass according to claim 8, further characterized in that the alkali oxide comprises Na2U in an amount of at least 8% molar.

11. A pharmaceutical packaging glass having a glass composition comprising: from approximately 70 mol% to approximately 80 mol% of SiO2, an alkaline earth oxide comprising MgO and CaO and a ratio (CaO(molar %) / (CaO(molar %)+MgO(molar %))) is greater than 0 and less than or equal to 0.5; X mol% of Al2O3, wherein X is from approximately 5 to less than 7; and Y mol% of alkali oxide comprising non-zero amounts of Na2O and K2O, wherein Y is from approximately 9 mol% to approximately 14 mol%.

12. The pharmaceutical packaging glass according to claim 11, further characterized in that the alkali oxide comprises Na2O in an amount of at least 8% molar.

13. The glass for pharmaceutical packaging according to claim 1, further characterized in that the coefficient of thermal expansion of the glass is less than 70x10'7K'1. bnoi 1 η / ι ζπζ / β / υιλι 14. The glass for pharmaceutical packaging according to claim 8, further characterized in that a coefficient of thermal expansion of the glass is less than 70x10'7K'1.

15. The glass for pharmaceutical packaging according to claim 11, further characterized in that a coefficient of thermal expansion of the glass is less than 70x10'7K'1.