阅读说明：本技术 具有高的耐水解性和低的色泽的可钢化玻璃 (Temperable glass with high hydrolysis resistance and low colour ) 是由 M·格林 R·E·艾希霍尔茨 于 2020-11-04 设计创作，主要内容包括：本发明涉及特别是适于药物包装的玻璃及玻璃产品。这种玻璃兼具化学强化性以及非常好的耐水解性和低的色泽。本发明还包括用于生产这种玻璃的方法及其用途。(The present invention relates to glass and glass products, particularly suitable for pharmaceutical packaging. The glass has both chemical strengthening property and very good hydrolysis resistance and low color. The invention also comprises a method for producing such a glass and the use thereof.)

1. A silicate glass, wherein the glass has a threshold diffusivity, D, of at least 6 μm²/h；

Wherein the hydrolysis resistance of the glass corresponds to at most 80% of the defined type I according to USP 660/glass particles;

wherein the glass has at least 12ppm Fe₂O₃(based on mol%); and

wherein the sum of the z-value and the x-value is at least 1.5 times higher than the y-value according to CIE 1931 color space when measured for a sample thickness of 1 mm.

2. The glass of claim 1, having the following composition:

composition (I) Mol％ SiO₂ 55-85 Al₂O₃ 5-25 Na₂O 5-20 K₂O 0.5-5 CaO 3.5-20 MgO 0.1-5 Fe₂O₃ 0.0012-0.1 TiO₂ 0-0.3 ZrO₂ 0.1-10 Cl 0.1-3

3. The glass of any of claims 1 and 2, wherein the glass comprises TiO₂Less than 500 ppm.

4. Glass according to any of the preceding claims, wherein the glass comprises ZrO₂The amount of (B) is 0.4 to 5 mol%.

5. The glass of any one of the preceding claims, wherein the glass has B₂O₃Less than 1 mol%.

6. The glass of any of the preceding claims, wherein the glass comprises Al₂O₃In a molar ratio higher than Na₂Molar ratio of O.

7. Glass according to any of the preceding claims, wherein the sum of the molar proportions of alkali metal oxides is lower than Al₂O₃In a molar ratio of (a).

8. A glass according to any preceding claim, wherein the molar ratio of CaO to the sum of CaO and MgO is greater than 0.5.

9. The glass of any of the preceding claims, wherein the glass has a transmittance of greater than 85% at 400nm wavelength, 495nm wavelength, and 670nm wavelength when measured for a sample thickness of 1mm and when measured for a sample thickness of 10 mm.

10. The glazing of any of the preceding claims, wherein the ratio of the transmission at 495nm to the transmission at 400nm ranges from 0.95: 1 to 1.05: 1 when measured for a sample thickness of 1mm and when measured for a sample thickness of 10 mm.

11. The glazing of any of the preceding claims, wherein, in CIE 1931 color space, the ratio of z-value to x-value is in the range of 1.1 to 1.3 and the ratio of z-value to y-value is in the range of 1.05 to 1.3, when measured for a sample thickness of 1mm and/or 10 mm.

12. The glass of any one of the preceding claims, wherein, when measured on a sample thickness of 1mm and/or 10mm, the ratio of y-value to x-value in CIE 1931 color space is between > 1: 1 to 1.05: 1, in the above range.

13. The glass of any one of the preceding claims, wherein the maximum crystallization rate, KG, in the temperature range of 800 ℃ to 1500 ℃ when the glass is heat treated in a gradient furnace at an elevated temperature for 60 minutes_maxAt most 0.05 μm/min.

14. The glazing of any preceding claim, wherein the glazing is chemically tempered;

preferably, DoL is in the range of 20 μm to 100 μm and Compressive Stress (CS) is in the range of 750MPa to 1000 MPa.

15. Use of a glass according to any of the preceding claims as primary packaging for a medicament.

16. A method for producing a glass according to any one of claims 1 to 14, the method comprising the steps of:

-treating the glass melt by a downdraw process, an overflow fusion process, a redraw process, a float process or a tube drawing process, and

-optionally tempering the glass by chemical tempering.

Technical Field

The present invention relates to glass and glass products, particularly suitable for pharmaceutical packaging. The glass has both chemical strengthening property and very good hydrolysis resistance and low color. The invention also comprises a method for producing such a glass and the use thereof.

Background

Glass articles used in the medical, especially pharmaceutical, field must meet stringent quality standards. Articles for primary packaging of pharmaceuticals (e.g. vials, ampoules, cartridges and syringes) must exhibit high transparency, good sterility and outstanding chemical resistance. Furthermore, glass cannot alter the quality of the material it contains or is in contact with in a way that exceeds a specified threshold, i.e. glass materials cannot release any amount of substances that, for example, impair the efficacy and stability of the contained drug or even make it toxic. Glasses for pharmaceutical packaging, such as pharmaceutical containers, also require high mechanical stability and durability, for example to avoid breakage of glass bottles containing medical drugs.

It is therefore desirable to provide a glass suitable for pharmaceutical containers that combines improved hydrolysis resistance with high mechanical stability. Such desired glasses should in particular exhibit a high transparency, while at the same time should be produced in a cost-effective manner.

In order to provide glass with high mechanical resistance, it is known to strengthen the glass, in particular to chemically strengthen the glass. For this purpose, the glass is ion exchanged to form a compressive stress layer which prevents mechanical damage and thus the glass is more damage tolerant. The ion exchange process is carried out in such a way that: at the glass surface, smaller alkali metal ions, such as sodium and/or lithium ions, are exchanged for larger alkali metal ions, such as potassium ions. The duration and temperature of the ion exchange process determines the depth of the exchange layer. If the ion exchange depth exceeds the depth of product surface damage during use, breakage is prevented.

The ion exchange under chemical strengthening is carried out, for example, by immersion in a potassium-containing salt melt. Ion exchange can also be carried out using aqueous potassium silicate solutions, pastes or dispersions, or by vapor deposition or temperature activated diffusion. The first of the above methods is generally preferred.

The compressive stress layer is characterized by a compressive stress and penetration depth parameter:

compressive Stress (CS) ("compressive stress" or "surface stress") is the stress that results from the substitution effect on the glass network across the surface of the glass after ion exchange, but without deformation of the glass.

The "depth of penetration" or "depth of ion exchange layer" or "depth of ion exchange" ("depth of layer" or "depth of ion exchange layer", DoL) is the thickness of the surface layer of glass where ion exchange occurs and compressive stress is generated. The compressive stress CS and the depth of penetration DoL can be measured optically using a commercially available stress meter FSM 6000.

"diffusivity" can be calculated from DoL and the chemical strengthening time t according to the following formula "D (also referred to as "threshold diffusivity, D"): DoL ═ 1.4 × sqrt (4 × D × t). In this disclosure, these are given in KNO₃Chemical strengthening at 450 ℃ for 9 hours. The indication of diffusivity does not imply that the corresponding article has undergone chemical strengthening. Diffusivity describes the susceptibility of an article to chemical strengthening with optional chemical strengthening.

Thus, ion exchange means that the glass is hardened or chemically strengthened by an ion exchange process, which is a process well known to those skilled in the art of glass manufacturing and processing. Typical salts for chemical strengthening are, for example, K-containing⁺A molten salt or a mixture of salts of (a). Commonly used salts include KNO₃、KCl、K₂SO₄Or K₂Si₂O₅. Additives such as NaOH, KOH, and other sodium or potassium salts, etc. are also used to better control the rate of chemically enhanced ion exchange. The glass composition has a great influence on the penetration depth and surface stress to be achieved.

Glasses commonly used in the pharmaceutical industry are borosilicate glasses (so-called neutral glasses) whose main constituents are silicon oxide and boron oxide, but may also contain aluminium, alkali metal and alkaline earth metal oxides.

Chemically strengthened glass articles, such as glass containers, of aluminosilicate glass play an important role in certain medical and especially pharmaceutical applications. Aluminosilicate glasses have the advantage that the glass articles can be strengthened and exhibit high mechanical stability. However, a disadvantage of the aluminosilicate glasses known from the prior art is that they provide poor hydrolysis resistance compared to, for example, borosilicate glasses. However, borosilicate glasses do not have as much strength as aluminosilicate glasses. Another disadvantage of the aluminosilicate glasses of the prior art is that in order to provide glasses with high transparency, costly raw materials are required. If low cost raw materials are used, the glass often exhibits undesirable color.

Disclosure of Invention

It is therefore an object of the present invention to avoid the above-mentioned disadvantages of the prior art and to provide a glass suitable for use in the medical, in particular pharmaceutical, field which combines good hydrolysis resistance with good mechanical strength. In particular, the glass articles should be suitable for use as primary packaging for pharmaceuticals and exhibit high transparency and low tint, while being producible from low-cost raw materials.

This object is achieved by the subject matter disclosed herein.

In a first aspect, the present invention provides a silicate glass, wherein the glass has a threshold diffusivity, D, of at least 6 μm²H, hydrolysis resistance class I (HGA 1 according to ISO 720: 1985 or type I according to USP 660/glass particles) and wherein the glass has Fe₂O₃The content is at least 0.0012 mol% (12 ppm).

In a second aspect, the present invention provides a silicate glass, wherein the sum of the z-value and the x-value is at least 1.5 times higher than the y-value according to CIE 1931 color space at a sample thickness of 1mm, and wherein the glass has a hydrolysis resistance class I (HGA 1 according to ISO 720: 1985, or type I according to USP 660/glass particles). The CIE 1931 color space represents a color impression by a combination of three values, namely an x-value, a y-value and a z-value.

In a third aspect, the present invention provides a silicate glass, wherein the glass has a threshold diffusivity, D, of at least 6 μm²H, wherein the glass has hydrolysis resistance class I (HGA 1 according to ISO 720: 1985, or type I according to USP 660/glass particles); and wherein the sum of the z-value and the x-value is at least 1.5 times higher than the y-value according to CIE 1931 color space at a sample thickness of 1 mm.

The glass of the present invention is preferably chemically strengthenable. The expression "chemically strengthenable" means that the glass can be chemically strengthened, i.e. it is susceptible to chemical strengthening. The degree of sensitivity of chemical strengthening is given as diffusivity D. In the present disclosure, the terms "strengthened, strengthenable and strengthened" on the one hand and "toughened, toughenable and toughened" on the other hand are used interchangeably.

Preferably, the glass of the invention has a threshold diffusivity, D, of at least 6 μm²H is used as the reference value. In the examples, the diffusivity ranges from 8 μm²H to 50 μm²/h、10μm²H to 35 μm²H or 15 μm²H to 30 mu m²H is used as the reference value. Some arePreferred glasses have a diffusivity of 20 μm²H to 25 μm²H is used as the reference value. Preferably, the glass of the invention has a threshold diffusivity, D, of at least 6 μm²H, more preferably at least 8 μm²H, more preferably at least 10 μm²H, more preferably at least 15 μm²H, more preferably at least 20 μm²H is used as the reference value. The high threshold diffusivity, D, of the glass of the present invention is a major advantage over prior art borosilicate glasses commonly used for pharmaceutical packaging.

The glass has a hydrolysis resistance class I (HGA 1 according to ISO 720: 1985 or type I according to USP 660/glass particles). The high hydrolysis resistance of the glass according to the invention is particularly advantageous for use as a pharmaceutical packaging. The glass of the invention has a hydrolysis resistance corresponding to at most 80%, preferably less than 80%, more preferably less than 79% of type I defined according to USP 660/glass granules.

The glass of the present invention has the main advantages of both excellent strengthening properties (especially high threshold diffusivity, D) and excellent hydrolysis resistance.

In general, a neutral white color impression is desired, especially in the field of pharmaceutical packaging. Other color impressions, in particular a yellowish-brown color impression, are generally not desired, since such glasses are "bad" or even "dirty" to the observer. Furthermore, an undesired color impression of the glass may affect the accurate inspection of the contents of the pharmaceutical package. Thus, in the prior art, Fe is produced₂O₃The glass content is very low to avoid the formation of Fe-Ti oxides which lead to a yellowish brown colour impression. Therefore, in order to make Fe₂O₃The content of (a) is as low as possible, and a very high purity of the raw material is required. Such raw materials are very expensive.

The inventors have found a process which provides glass with a good colour impression without the use of very expensive high purity raw materials. In particular, the glass of the present invention may comprise Fe in an amount of at least 12ppm (based on mol%), such as at least 20ppm, at least 30ppm, at least 40ppm, at least 50ppm, at least 60ppm, at least 70ppm, at least 80ppm or at least 90ppm₂O₃. However, Fe₂O₃The amount of (c) should not be very high. Preferably, Fe of the glass₂O₃The content is at most 0.1 mol% (1000ppm), more preferably at most 500ppm, more preferably at most 250ppm, more preferably at most 125 ppm.

The color impression of glass can be described by a position according to the CIE 1931 color space. Preferably, the glass of the present invention is such that the sum of the z value and the x value is at least 1.5 times higher than the y value. Such glasses impart a particularly good color impression, which is far from the undesirable yellowish-brown impression.

Preferably, the glass of the invention comprises the following constituents in mol%:

composition (I)	Mol％
		SiO2	55-85
Al2O3	5-25
		Na2O	5-20
K2O	0.5-5
		CaO	3.5-20
MgO	0.1-5
		Fe2O3	0.0012-0.1
TiO2	0-0.3
		ZrO2	0.3-10
Cl	0.1-3

Preferably, the glass of the present invention is an aluminosilicate glass. Compared to borosilicate glasses which are generally used in the prior art, aluminosilicate glasses have a particularly advantageous threshold diffusivity, D.

The glass is a silicate glass, i.e. it contains a large amount of SiO₂. SiO contained in the glass of the present invention₂The amount of (b) is preferably 55 to 85 mol%, more preferably 60 to 80 mol%, more preferably 65 to 75 mol%, more preferably 65 to 70 mol%, more preferably 66 to 69 mol%. If SiO₂The chemical resistance may be lowered if the amount of (A) is low. If SiO₂At high quantities, the processing temperature rises and may impair production.

Preferably, the glass of the invention comprises Al₂O₃The amount of (b) is 5 to 25 mol%, more preferably 7.5 to 20 mol%, more preferably 10 to 15 mol%, more preferably 11 to 13 mol%. Compared with borosilicate glasses, aluminosilicate glasses have a particularly favorable threshold diffusivity, D. However, Al₂O₃The amount of (a) should not be very high because aluminosilicate glasses generally have higher melting temperatures than borosilicate glasses. Especially if Al is present₂O₃At high levels, the glass may be difficult to melt, require higher energy input, and/or may be difficult to shape due to elevated processing temperatures (VA). On the contrary, if Al₂O₃The amount of (A) is low, the chemical resistance is impaired.

Preferably, the glasses of the invention contain Na₂The amount of O is 5 to 20 mol%, more preferably 6 to 15 mol%, more preferably 7 to 12 mol%, more preferably 8 to 11 mol%. For chemical strengthening, this Na₂The amount of O is particularly preferred. If Na is present₂The amount of O is high, hydrolysis resistance may be deteriorated due to alkali leaching.

Preferably, the glasses of the invention comprise K₂The amount of O is 0.5 to 5 mol%, more preferably 0.6 to 2 mol%, more preferably 0.7 to 1.5 mol%, more preferably 0.8 to 1.3 mol%. K₂O can improve the devitrification resistance. Furthermore, K₂The alkaline leachability of O is low. However, if K₂The high amount of O may impair hydrolysis resistance. Furthermore, K₂O increases the coefficient of thermal expansion, resulting in lower thermal shock resistance, which is also disadvantageous during further processing. A large number of K₂O can also interfere with the ion exchange capacity of the glass and reduce the diffusivity and/or depth of penetration (DoL) during chemical strengthening. Therefore, it is preferable to limit K as described above₂The amount of O.

The term "R₂O "means an alkali metal oxide Li₂O、Na₂O and K₂And O. The glass of the present invention may contain Li in an amount of, for example, 0.1 mol% to 1 mol%₂And O. Preferably, however, the glasses of the invention do not contain Li₂O。Li₂O is associated with increased cost and its availability is limited, especially due to other applications such as lithium ion batteries. Preferably, Na₂O is the main alkali metal oxide of the glass of the present invention. Preferably, Na₂O and R₂The molar ratio of O is in the range of 0.75: 1 to 1: 1, more preferably in the range of 0.85: 1 to 0.95: 1. This is advantageous, in particular, with regard to hydrolysis resistance and chemical strengthening.

Preferably, the glass of the invention comprises CaO in an amount of 3.5 to 20 mol%, more preferably 4 to 15 mol%, more preferably 5 to 10 mol%, more preferably 6 to 9 mol%, more preferably 7.2 to 8 mol%. CaO is an alkaline earth metal oxide and is used to adjust the viscosity of the glass (to optimize melting behavior). CaO lowers the melting point of the glass so that it can be melted with less energy. Conversely, too high a content of calcium oxide may deteriorate the ion exchange capacity/diffusivity of the glass to such an extent that the DoL value is reduced. In addition, the ion exchange capacity of the exchange bath is impaired, i.e. the ion exchange bath has to be replaced more frequently. Therefore, it is advantageous to adjust the amount of CaO to the above range.

Preferably, the glass of the invention comprises MgO in an amount of 0.1 to 5 mol%, more preferably 0.2 to 1.5 mol%, more preferably 0.3 to 1 mol%, more preferably 0.4 to 0.5 mol%. MgO is particularly advantageous for adjusting the viscosity of the glass. MgO lowers the melting point of the glass and contributes to better melting of the glass. The ion exchange capacity of the glass can be increased by MgO. However, if the content of MgO is high, devitrification resistance is deteriorated.

The term "RO" refers to the alkaline earth oxides MgO, CaO, BaO and SrO. The glass of the present invention may contain BaO and/or SrO, for example, each in an amount of 0.1 to 1 mol%. Preferably, however, the glasses of the present invention do not contain BaO and/or SrO. Preferably, CaO is the principal alkaline earth oxide of the glass of the present invention. Preferably, the molar ratio of CaO to RO is in the range of 0.8: 1 to 1: 1, more preferably in the range of 0.9: 1 to 0.98: 1. In particular, it is preferred that the molar ratio of CaO to the sum of CaO and MgO is greater than 0.5, more preferably at least 0.6, more preferably at least 0.7, especially in the range of 0.8: 1 to 1: 1, more preferably in the range of 0.9: 1 to 0.98: 1. In other embodiments, the sum of the molar ratios of CaO and MgO may be at least 1.7 times greater than the molar ratio of CaO.

Preferably, the glasses of the invention comprise TiO₂The amount is 0 to 0.3 mol%, more preferably 0 to 0.2 mol%, more preferably 0 to 0.1 mol%, more preferably 0 to 0.05 mol%. TiO 2₂Can help to improve chemical resistance. However, it is particularly preferred that the glass according to the invention is TiO-free₂。TiO₂Possibly with Fe₂O₃React and lead to a yellowish-brown coloration of the glass. Therefore, it is preferable to limit TiO in the glass₂The amount of (c).

Preferably, the glass of the invention comprises ZrO₂The amount is 0.1 to 10 mol%, more preferably 0.3 to 10 mol%, more preferably 0.4 to 5 mol%, more preferably 0.5 to 10 mol%, more preferably 0.6 to 1.5 mol%. In particular, ZrO₂Can be used as TiO₂Alternative(s) to (3). ZrO (ZrO)₂The amount of (b) is preferably at most 10 mol%, more preferably at most 7.5 mol%, more preferably at most 5 mol%, such as at most 4.5 mol%, at most 3 mol% or at most 1.5 mol%. ZrO (ZrO)₂Hydrolysis resistance can be increased. In particular, ZrO₂Can be formed, for example, by forming [ ZrO ]₃]^2-And Ca²⁺To stabilize the glass structure, which reduces Ca²⁺The mobility of the ions. Furthermore, ZrO₂The ion-exchange property of the glass can be improved so that a higher CS value can be achieved. However, a large amount of ZrO₂The processing temperature may be increased and resistance to devitrification may be decreased.

Preferably, the glass of the invention comprises Cl in an amount of from 0.1 to 3 mol%, more preferably from 0.2 to 2 mol%, more preferably from 0.3 to 1 mol%, more preferably from 0.4 to 0.6 mol%. In particular, Cl may act as a fining agent.

The glass of the invention may comprise B, for example, in an amount of at least 0.1 mol%₂O₃. However, in the glass of the present invention B₂O₃The amount of (b) is preferably less than 1 mol%, more preferably less than 0.5 mol%. B is₂O₃May impair the chemical strengthening ability of the glass. Therefore, the glass of the present invention preferably does not contain B₂O₃。

As mentioned above, Fe is present in the glass₂O₃And TiO₂Both of which lead to undesirable yellow-brown coloration of the glass. Reduction of Fe₂O₃The amounts of (A) require the use of particularly pure starting materials and therefore lead to high costs. Thus, in contrast, the present invention relates to the reduction of TiO₂The amount of (c). In particular, it is preferred that Fe in the glass₂O₃In a molar ratio of at least TiO₂Is equally high. More preferably, Fe is in the glass₂O₃Is higher than TiO₂In a molar ratio of (a).

As described above, ZrO₂Can be used as TiO₂Alternative(s) to (3). Preferably, ZrO in the glass₂Molar ratio of (A) to (B) TiO₂Is at least 5 times, more preferably at least 10 times, more preferably at least 20 times, more preferably at least 50 times higher. Likewise, ZrO₂With Fe₂O₃Is preferably in proportion to TiO₂With Fe₂O₃Is at least 5 times, more preferably at least 10 times, more preferably at least 20 times, more preferably at least 50 times higher than the molar ratio of (a). As mentioned above, Fe is present in the glass₂O₃And TiO₂Both of which lead to undesirable yellow-brown coloration of the glass. Thus, it is advantageous to use ZrO₂As TiO₂Alternative(s) to (3). Furthermore, ZrO due to another reason₂Is advantageous. I.e. in comparison with TiO₂Influence on CS and DoL, ZrO₂The impact on CS and DoL is greater. Thus, with TiO₂Compared with ZrO₂Improved chemical tempering results are obtained.

As mentioned above, Fe may be present in the glass of the present invention₂O₃. It is not necessary to use very pure raw materials to avoid Fe₂O₃This is a particular advantage of the present invention. However, Fe₂O₃Should not be present in very high amounts. In particular, preference is given to ZrO₂In comparison with the amount of Fe₂O₃The amount of (c) is low. Preferably, ZrO in the glass₂Molar ratio of Fe₂O₃Is at least 5 times, more preferably at least 10 times, more preferably at least 20 times, more preferably at least 50 times higher. However, ZrO in the glass₂Is preferably in proportion to Fe₂O₃Is at most 100 times higher.

As described above, Al is used for chemical strengthening of glass₂O₃And Na₂O is both advantageous. Compared with borosilicate glasses, aluminosilicate glasses have a particularly favorable threshold diffusivity, D. Furthermore, sodium is typically exchanged for potassium during chemical strengthening, so that a certain amount of Na is present₂O is preferably present in the glass. However, Al in the glass₂O₃Is preferably higher than Na₂Molar ratio of O. Preferably, Al₂O₃With Na₂The molar ratio of O is in the range of 1.05: 1 to 1.35: 1, more preferably in the range of 1.1: 1 to 1.3: 1. This is particularly advantageous in terms of chemical resistance, hydrolysis resistance and ion exchange properties.

Preferably, the glass of the present invention comprises Al₂O₃And an alkali metal oxide R₂And O. However, it is preferred that the alkali metal oxide R₂The sum of the molar ratios of O is not more than Al₂O₃In a molar ratio of (a). Preferably, the alkali metal oxide R₂The sum of the molar proportions of O being lower than that of Al₂O₃In a molar ratio of (a). Preferably, R₂O and Al₂O₃In a molar ratio of from 0.8: 1 to 1: 1, more preferably from 0.85: 1 to < 1: 1. This is particularly advantageous in terms of chemical resistance, hydrolysis resistance and ion exchange properties.

Interestingly, Al was found₂O₃The molar ratio of CaO is related to the ability of the glass to chemically strengthen. Preferably, Al in the glass₂O₃Is at least 1.1 times, more preferably at least 1.2 times, more preferably at least 1.3 times, more preferably at least 1.4 times, more preferably at least 1.5 times higher than the molar ratio of CaO. However, Al₂O₃The molar ratio to CaO should not be very high, otherwise the melting temperature may increase significantly. Preferably, Al in the glass₂O₃Is at most 2 times, more preferably at most 1.9 times, more preferably at most 1.8 times, more preferably at most 1.7 times, more preferably at most 1.6 times higher than the molar ratio of CaO.

As mentioned above, the glass of the present invention is preferably an aluminosilicate glass. However, the glass preferably comprises other components as described above. Preferably, SiO₂And Al₂O₃In the range of 70 mol% to 90 mol%, more preferably in the range of 75 mol% to 85 mol%. Particularly preferably, SiO₂And Al₂O₃The sum of the molar proportions of (A) and (B) is less than 82 mol%。

When in this specification it is mentioned that glasses do not contain a certain component or that they do not contain a certain component, this means that only that component is allowed to be present as an impurity in the glass. Meaning that it is not added in substantial amounts. The non-substantial amount is an amount of less than 300ppm (mol), preferably less than 200ppm (mol), more preferably less than 100ppm (mol), particularly preferably less than 50ppm (mol) and most preferably less than 10ppm (mol). Preferably, the glass of the present invention does not contain F, SnO₂And/or CeO₂。

The glass of the present invention has excellent transmittance. Preferably, the transmission of the glass at a wavelength of 400nm is higher than 85%, more preferably higher than 90%, at a sample thickness of 1 mm. Preferably, the glass has a transmittance at a wavelength of 495nm of higher than 85%, more preferably higher than 90%, at a sample thickness of 1 mm. Preferably, the transmission of the glass at a wavelength of 670nm is higher than 85%, more preferably higher than 90%, at a sample thickness of 1 mm. Preferably, the transmission of the glass at a wavelength of 400nm is higher than 75%, more preferably higher than 85%, at a sample thickness of 10 mm. Preferably, the glass has a transmittance at a wavelength of 495nm higher than 75%, more preferably higher than 85%, at a sample thickness of 10 mm. Preferably, the transmission of the glass at a wavelength of 670nm is higher than 75%, more preferably higher than 85%, at a sample thickness of 10 mm. Preferably, the transmittance of the glass at 495nm is at most 5% higher than the transmittance at 400nm at a sample thickness of 1 mm. Preferably, the transmittance of the glass at 495nm is at most 5% higher than the transmittance at 400nm at a sample thickness of 10 mm. Preferably, the transmission at 400nm for a glass of 10mm sample thickness is at most 5% lower than for a glass of 1mm sample thickness.

Preferably, the transmission of the glass at wavelengths of 400nm, 495nm and 670nm is higher than 85%, more preferably higher than 90%, at a sample thickness of 1 mm. Preferably, the transmission of the glass at wavelengths of 400nm, 495nm and 670nm is higher than 75%, more preferably higher than 85%, at a sample thickness of 10 mm.

Preferably, the transmission of the glass at wavelengths of 400nm, 450nm, 495nm, 550nm, 600nm, 650nm and 670nm is higher than 85%, more preferably higher than 90%, at a sample thickness of 1 mm. Preferably, the transmission of the glass at wavelengths of 400nm, 450nm, 495nm, 550nm, 600nm, 650nm and 670nm is higher than 75%, more preferably higher than 85%, at a sample thickness of 10 mm.

Preferably, the glass of the present invention has a high transmittance in the visible region. Preferably, the transmission of the glass at any wavelength over the entire wavelength range from 380nm to 780nm is higher than 50%, more preferably higher than 60%, more preferably higher than 70%, more preferably higher than 80%, more preferably higher than 85%, more preferably higher than 90% at a sample thickness of 1 mm. Preferably, the transmission of the glass at any wavelength over the entire wavelength range from 380nm to 780nm is higher than 50%, more preferably higher than 60%, more preferably higher than 70%, more preferably higher than 75%, more preferably higher than 80%, more preferably higher than 85% at a sample thickness of 10 mm.

Preferably, the glasses of the invention have a high transmission in the visible region, especially at wavelengths of 400nm, 495nm and 670 nm. Preferably, the transmittances at 400nm, 495nm and 670nm are very similar.

Preferably, at a sample thickness of 1mm and/or a sample thickness of 10mm, the ratio of the transmission at 495nm to the transmission at 400nm is in the range of 0.95: 1 to 1.05: 1, more preferably in the range of 0.97: 1 to 1.04: 1, more preferably in the range of 0.99: 1 to 1.03: 1, more preferably in the range of 1: 1 to 1.02: 1. It is particularly preferred that the transmission at 495nm is higher than the transmission at 400 nm. Most preferably, the ratio of the transmission at 495nm to the transmission at 400nm is between > 1: 1 to 1.015: 1, in the above range.

Preferably, at a sample thickness of 1mm and/or a sample thickness of 10mm, the ratio of the transmission at 670nm to the transmission at 495nm is in the range of 0.95: 1 to 1.05: 1, more preferably in the range of 0.96: 1 to 1.03: 1, more preferably in the range of 0.97: 1 to 1.02: 1, more preferably in the range of 0.98: 1 to 1.01: 1, in the above range.

Preferably, the ratio of the transmission at 670nm to the transmission at 400nm is in the range of 0.95: 1 to 1.05: 1, more preferably in the range of 0.96: 1 to 1.04: 1, more preferably in the range of 0.97: 1 to 1.03: 1, more preferably in the range of 0.98: 1 to 1.02: 1, more preferably in the range of 0.99: 1 to 1.01: 1 at a sample thickness of 1mm and/or a sample thickness of 10 mm.

As mentioned above, the glass of the present invention is preferably chemically temperable. The invention also relates to a tempered glass, in particular a chemically tempered glass. Preferably, the ratio of the Central Tension (CT) to the Compressive Stress (CS) is in the range of 0.05 to 2.0. Especially in KNO₃In the chemical tempering at 450 ℃ for 12 hours, the DoL is preferably in the range of 20 to 100. mu.m, more preferably 25 to 75 μm, more preferably 30 to 60 μm, more preferably 35 to 50 μm. The Central Tension (CT) is preferably in the range of 100MPa to 200 MPa. The Compressive Stress (CS) is preferably in the range of 750MPa to 1000MPa, more preferably in the range of 800MPa to 900 MPa. In a particularly preferred embodiment, the chemically tempered glass of the present invention has a CS of at least 840MPa and a DoL of at least 30 μm, more preferably a CS of at least 840MPa and a DoL of at least 40 μm.

As described above, a color impression can be described based on the CIE 1931 color space, which expresses a color impression by a combination of three values, i.e., an x-value, a y-value, and a z-value (chromaticity coordinates). Preferably similarly to DIN5033, determination is made using illuminant "C" of 6770K for a CIE standard observer within the foveal 2 ° arc (CIE 19312 ° standard observer). Briefly, X, Y and Z standard spectral values were obtained from the tables of the CIE 1931 color space system and multiplied by the measured transmittance values to obtain the corresponding tristimulus values.

By normalizing the sum x + y + z to be equal to 1, the chromaticity coordinates x, y and z defining a color position or a color position within the color space are obtained. Thus, the x, y, and z values are positive values and x + y + z is 1. The CIE 1931 color space chromaticity diagram represents a color space, where the x-axis represents x-values and the y-axis represents y-values. The z value can be inferred from any given pair of x and y values by calculating z 1-x-y. The point x, y, z, 1/3 represents the so-called "white point", which defines the color "white". The high x value indicates red. A high y value represents green. High z values indicate blue. Each chromaticity is represented as a particular color location in a color space. The mixed colors of the additives have their color positions on the straight connecting lines of the components. To accurately characterize the color stimulus specification, the tristimulus value Y is used as a luminance reference value (DIN5033, part 1) by dividing the sum of all Y values by a ratio (21.293658). Thereby normalizing the resulting value to a maximum value of 100. This value indicates that the glass is brighter or darker to the human eye than the contrast probe.

The x, y and z values are positive values and x + y + z is 1. The CIE 1931 color space chromaticity diagram represents a color space, where the x-axis represents x-values and the y-axis represents y-values. The z value can be inferred from any given pair of x and y values by calculating z 1-x-y. The point x, y, z, 1/3 represents the so-called "white point", which defines the color "white". The high x value indicates red. A high y value represents green. High z values indicate blue.

Preferably, the value of x in the CIE 1931 color space is at least 0.30 and at most 0.35, more preferably at least 0.31 and at most 0.32 at a sample thickness of 1mm and/or 10 mm. Preferably, the y-value in CIE 1931 color space is at least 0.30 and at most 0.35, more preferably at least 0.31 and at most 0.32 at a sample thickness of 1mm and/or 10 mm. Preferably, the values of x and y are at least 0.30 and at most 0.35, more preferably at least 0.31 and at most 0.32 at a sample thickness of 1mm and/or 10 mm.

As mentioned above, a neutral white color impression is desired, especially in the field of pharmaceutical packaging. In contrast, a yellowish-brown color impression is not desired. A neutral white color impression is represented by x-y-z-1/3, which is therefore a potential embodiment of the invention when the sample thickness is 1mm and/or 10 mm. However, a color impression slightly different from a neutral white color is actually even more preferred. It is therefore preferred that the z-value is greater than 1/3, preferably greater than 0.34, more preferably greater than 0.35, more preferably greater than 0.36, more preferably at least 0.37 or even greater than 0.37 at a sample thickness of 1mm and/or 10 mm. However, in order not to make the glass too blue, the z-value should not be too high. Particularly preferably, the z-value is in the range of 0.37 to 0.38, more preferably in the range of >0.37 to 0.375, more preferably in the range of 0.371 to 0.374, at a sample thickness of 1mm and/or 10 mm.

In general, the z value of the sample thickness at 10mm can be smaller compared to a sample thickness of 1 mm. For example, the difference between the z value of the sample thickness at 1mm and the z value of the sample thickness at 10mm may be in the range of 0.0001 to 0.005, more preferably in the range of 0.0005 to 0.002. Thus, at a sample thickness of 10mm, the z-value is preferably in the range >0.37 to 0.375, more preferably 0.371 to 0.373.

Preferably, the ratio between the z-value and the x-value is in the range of 1.1 to 1.3, more preferably in the range of 1.15 to 1.25 at a sample thickness of 1mm and/or 10 mm. Preferably, the ratio between the z-value and the y-value is in the range of 1.05 to 1.3, more preferably in the range of 1.1 to 1.25 at a sample thickness of 1mm and/or 10 mm.

The results show that the color impression of the glass is particularly advantageous if the value of y is greater than the value of x. However, the difference between the y value and the x value should not be too large. Preferably, the y value in CIE 1931 color space is at most 1.1 times greater than the x value at a sample thickness of 1mm and/or 10 mm. Preferably, at a sample thickness of 1mm and/or 10mm, the ratio of the y value to the x value is between > 1: 1 to 1.05: 1, more preferably 1.01: 1 to 1.03: 1, more preferably 1.015: 1 to 1.025: 1, in the above range.

Preferably, the value of x is in the range of 0.31 to 0.312, more preferably 0.31 to 0.311 at a sample thickness of 1mm and/or 10 mm. Preferably, at a sample thickness of 1mm and/or 10mm, the y value is in the range of 0.316 to 0.318. Preferably, the value of the thickness y of the sample at 1mm is in the range of 0.316 to 0.317 and/or the value of the thickness y of the sample at 10mm is in the range of 0.317 to 0.318. Preferably, at a sample thickness of 1mm and/or 10mm, the value of x is in the range of 0.31 to 0.312, more preferably 0.31 to 0.311, and at a sample thickness of 1mm and/or 10mm, the value of y is in the range of 0.316 to 0.318. Preferably, the value of x is in the range of 0.31 to 0.312, more preferably 0.31 to 0.311, at a sample thickness of 1mm and/or 10mm, and the value of y is in the range of 0.316 to 0.317 at a sample thickness of 1mm and/or in the range of 0.317 to 0.318 at a sample thickness of 10 mm.

Generally, the value of the sample thickness y at 10mm can be higher compared to a sample thickness of 1 mm. For example, the difference between the y value of the sample thickness of 10mm and the y value of the sample thickness of 1mm may be in the range of 0.0005 to 0.002, more preferably in the range of 0.00075 to 0.0015.

When referring to "sample thickness," the thickness refers to the thickness of the sample on which the corresponding parameter can be measured. The sample thickness is not meant to be the actual thickness of the glass or glass article, and the thickness of the glass or glass article is in no way limited to the sample thickness.

Preferably, the glass has a y-value at 10mm which is at most 10%, more preferably at most 5%, more preferably at most 1%, more preferably at most 0.5% higher than the thickness of the sample at 1 mm. Preferably, the thickness of the sample at 10mm is 0.1% to 0.5%, more preferably 0.25% to 0.4% higher than the thickness of the sample at 1 mm.

Preferably, the z-value of the glass is at most 10%, more preferably at most 5%, more preferably at most 1%, more preferably at most 0.5% lower for a sample thickness at 10mm than for a sample thickness at 1 mm. Preferably, the thickness of the sample with z value at 10mm is 0.1% to 0.5%, more preferably 0.15% to 0.4% lower than the thickness of the sample at 1 mm.

Preferably, the glass has an average coefficient of linear thermal expansion CTE greater than 3 x 10 over the temperature range of 25 ℃ to 300 ℃^-6/℃。

Preferably, the glass of the invention has a thickness of 0.1mm to 5mm, more preferably 0.4mm to 2.5 mm. Preferably, the glass of the invention is a glass tube, in particular a glass tube having a wall thickness of 0.1mm to 5mm, more preferably 0.4mm to 2.5 mm.

According to USP660, the consumption of hydrochloric acid per gram of glass particles in the glass particles test is at most 0.081ml/g, preferably less than 0.080ml/g, more preferably less than 0.079 ml/g.

Preferably, the glass does not devitrify at temperatures of 800 ℃ to 1500 ℃.

Devitrification resistance may be in accordance with KG_maxAnd (4) showing. KG_maxThe lower the devitrification resistance, the higher. KG_maxMeans the maximum crystallization rate in μm/min. The measurement of crystallization rate is well known. The crystallization rate is measured along the formed crystals, i.e. in the direction of their largest dimension. In particular, the crystallization rate is determined when the glass is subjected to gradient strengthening (e.g., using a gradient furnace).

The so-called Lower Devitrification Temperature (LDT) is the temperature at which devitrification starts in the temperature raising scheme. Above the liquidus temperature (also known as the Upper Devitrification Temperature (UDT)), crystals do not appear even for a long time. LDT and UDT values typically vary from glass to glass. Unless otherwise indicated, the terms "crystalline" and "devitrification" are used synonymously herein.

If present, crystallization occurs at a temperature above the Lower Devitrification Temperature (LDT) and below the Upper Devitrification Temperature (UDT), thus ranging between LDT and UDT. Thus, the temperature at which the crystallization rate reaches a maximum is between LDT and UDT. The glass must be heated to a temperature between the LDT and UDT to determine the KG_max. Typically, different temperatures in the LDT to UDT range are tested, as it is generally not known at which temperature the maximum crystallization occurs precisely. This also enables LDT and UDT to be determined as the lower and upper limits, respectively, of the temperature range in which crystallization occurs.

The crystallization rate is preferably determined by heat-treating the glass in a gradient furnace at elevated temperature for one hour. A gradient furnace is a furnace with different heating zones and thus different temperature zones. By ramp-up is meant that the temperature of the glass is lower than the temperature of any region of the furnace prior to being placed in the furnace. Therefore, the temperature of the glass is raised by putting the glass into the furnace, regardless of which region of the furnace the glass is put into. Therefore, the measurement of devitrification is preferably performed by heat treatment for one hour in a (pre-heated) gradient furnace having different temperature zones. This is a location based gradient rather than a time based gradient because the gradient furnace is divided into locations or zones of different temperatures.

A furnace divided into several heating zones is capable of testing different temperatures simultaneously. This is a particular advantage of gradient furnaces. For example, the minimum temperature may be 800 ℃ and the maximum temperature may be 1500 ℃, the minimum temperature may be 1025 ℃ and the maximum temperature may be 1210 ℃, the minimum temperature may be 1050 ℃ and the maximum temperature may be 1450 ℃, the minimum temperature may be 1100 ℃ and the maximum temperature may 1395 ℃ or the minimum temperature may be 1060 ℃ and the maximum temperature may be 1185 ℃. The temperatures are selected such that the crystallization rates can be determined at different temperatures in the range of LDT and UDT, so as to compare the potentially different crystallization rates in that range to determine KG_maxThe maximum crystallization rate. If the LDT and UDT are unknown, it is preferable to test temperatures in a relatively large range to be able to ensureLDT and UDT. For example, the lowest temperature in the gradient furnace may be selected such that it is about 350K below the processing temperature (VA) of the glass.

Preferably, the glass of the invention is devitrification resistant such that, upon heat treatment of the glass in a gradient furnace at elevated temperature for 60 minutes, KG is at a temperature in the range of 800 ℃ to 1500 ℃, e.g. in the range of 1025 ℃ to 1210 ℃, in the range of 1050 ℃ to 1450 ℃, in the range of 1100 ℃ to 1395 ℃ or in the range of 1060 ℃ to 1185_maxPreferably at most 0.05 μm/min, more preferably at most 0.02 μm/min, more preferably at most 0.01 μm/min. Most preferably, no devitrification occurs at all. Importantly, if no devitrification occurs at all during the gradient reinforcement, the KG cannot be determined_max. The absence of devitrification can also be expressed as KG_max＝0μm/min。

It is noteworthy that the maximum crystallization rate (KG) of the glass in the temperature range of 800 ℃ to 1500 ℃ is achieved when the glass is heat-treated in a gradient furnace for 60 minutes at elevated temperature_max) The fact that it is at most 0.05 μm/min does not mean that the gradient furnace must cover the whole range of 800 ℃ to 1500 ℃. For example, if the UDT for a given glass is known to be 1200 ℃, then it is not necessary to test temperatures in excess of 1200 ℃ in a gradient furnace, since there is no crystallization at this temperature, so the maximum crystallization rate KG_maxMust be at a temperature below 1200 c. Likewise, if the UDT is known to be 1450 ℃, 1395 ℃, 1210 ℃ or 1185 ℃, it is not necessary to test temperatures above 1450 ℃, 1395 ℃, 1210 ℃ or 1185 ℃ in a gradient furnace.

Preferably, glass particles, in particular glass particles having a diameter of 1.6mm to 4mm, are used to determine the crystallization rate. Such glass particles are preferably placed on a support, such as a platinum support for gradient strengthening. For example, the carrier may have recesses, each recess for receiving a glass particle, with a hole at the bottom of each recess so that the crystallization rate can be determined by microscopy. In view of the preferred size of the glass particles, the diameter of each depression is preferably 4mm, while the diameter of each hole is preferably 1 mm.

After the heat treatment, it can be determined by microscopy which temperature range has occurred at whichThe rate of crystallization. The highest crystallization rate determined is the maximum crystallization rate KG_max. LDT and UDT can be determined as the lower and upper limits, respectively, of the temperature range in which crystallization occurs. Different glass particles can easily be assigned to different temperature zones of the gradient furnace, since it is known at which position in the furnace has which temperature during the heat treatment and which glass particles are located at which position in the furnace.

The invention also relates to the use of the glass according to the invention for producing containers, in particular pharmaceutical containers.

In one aspect, the invention relates to a method for producing the glass of the invention, comprising the steps of:

-melting a glass raw material,

-cooling the obtained glass.

In one aspect, the invention relates to a method for producing a glass according to the invention, comprising the steps of:

-treating the glass melt, in particular by a downdraw process, an overflow fusion process, a redraw process, a float process or a tube drawing process, in particular a danner process, a vilo process or a vertical drawing process.

In some aspects, the method comprises the steps of:

tempering the glass by physical and/or chemical tempering.

Chemical tempering is particularly preferred. Preferably, the chemical tempering comprises an ion exchange process. Preferably, the ion exchange process comprises immersing the glass or a portion of the glass in a salt bath comprising monovalent cations. Preferably, the monovalent cation is potassium, sodium or a mixture of potassium and sodium. Potassium ion is particularly preferred. Preferably, KNO is used₃. Preferably, the chemical tempering is performed at a temperature of 320 ℃ to 700 ℃, more preferably 400 ℃ to 500 ℃. Preferably, the total duration of chemical tempering is between 5 minutes and 48 hours, more preferably between 1 hour and 24 hours, more preferably between 4 hours and 15 hours, more preferably between 5 hours and 12 hours. Particularly preferred is that in KNO₃Chemical tempering at 450 deg.c for 9 hr.

The glass of the present invention may be in any form. The glass according to the invention may be, for example, a glass container, a glass sheet, a glass plate, a glass rod, a glass tube, a glass block or other articles useful in, for example, the pharmaceutical or medical field.

The invention also relates to a primary package for a medicament comprising the glass of the invention. The primary package of the medicament is preferably selected from a bottle such as a large or small bottle (e.g. an injection bottle) or a small bottle, ampoule, cartridge, bottle, flask, vial, beaker or syringe.

The term "primary package of a medicament" is understood to mean a package made of glass which is in direct contact with the medicament. The packaging protects the drug from the environment and preserves the drug according to its specifications until use by the patient.

Glass in the form of a glass container may be used as primary packaging for a medicament. The glass may be contacted with liquid contents, such as solutions of active ingredients, solvents such as buffer systems, and the like, which may have a pH in the range of 1 to 11, or 4 to 9, or 5 to 7. Glass has particularly good chemical resistance and is therefore particularly suitable for storing or preserving these contents. In the context of the present invention, particularly good chemical resistance means that the glass meets to a large extent the requirements for storage and preservation of liquid contents suitable for the pharmaceutical field, and in particular means that the glass has a hydrolysis resistance corresponding to hydrolysis class 1 according to ISO720 or USP 660.

The glass according to the invention is suitable for the manufacture of pharmaceutical containers which are in contact with their contents and which can therefore be provided for storing and preserving these contents. Inclusions which can be used are, for example, all solid and liquid compositions used in the pharmaceutical field.

The properties of glass make it very suitable for a wide variety of applications, for example for use as primary packaging for pharmaceuticals (e.g. cartridges, syringes, ampoules or vials), since the substances stored in the containers, in particular aqueous solutions, do not cause any significant attack on the glass.

The invention also relates to pharmaceutical products and pharmaceutical formulations comprising the glasses of the invention. The pharmaceutical formulation may comprise a biopharmaceutical, such as an antibody, an enzyme, a protein, a peptide, etc., and one or more pharmaceutically acceptable excipients.

The glass according to the invention may also be an intermediate product in the production of another glass product, such as a tubular glass in the form of a semi-finished product, for example for further processing into pharmaceutical primary packaging.

In the following, the invention is described in more detail with reference to exemplary and comparative examples, which illustrate the teachings of the invention but are not intended to limit the invention.

Drawings

Fig. 1 shows the positions of example glasses E2 and E3 and comparative examples C1 and C2 in the CIE 1931 color space. The x-axis represents the x-value and the y-axis represents the y-value.

Fig. 2 shows an enlarged view of fig. 1, focusing on x values of 0.314 to 0.32 and y values of 0.308 to 0.314. The position of the comparative example C1 of 10mm thickness is outside the focus area and is therefore not shown in fig. 2.

Detailed Description

Glass composition

Table 1 shows the components of examples E1-E3 and comparative examples C1-C3 in mol%.

TABLE 1

Composition (I)	E1	E2	E3	C1	C2	C3
							SiO2	68.0	68.1	68.1	68.5	69.0	75.8
Al2O3	12.1	11.65	11.5	11.2	11.5	5.73
							Na2O	9.7	9.97	9.7	10.1	9.5	11.4
K2O	1.1	1.15	1.2	0.98	1.128	0.09
							MgO	0.5	0.49	0.5	-	0.4	6.59
CaO	7.6	7.61	7.4	7.0	7.15	0.36
							Cl	0.39	0.42	0.4	-	0.39	0.025
F	-	-	-	0.7	-	-
							ZrO2	0.6	0.6	1.2	-	-	-
TiO2	0.008	0.008	-	1.48	0.93	-
							Fe2O3	0.009	0.0094	0.0044	0.0053	0.0024	0.0054
SnO2	-	-	-	0.02	-	-
							CeO2	-	-	-	0.01	-	-

Exemplary glasses E1-E3 contain ZrO₂Rather than TiO₂. This enables the use of a composition containing Fe₂O₃To reduce costs without compromising the desired near neutral white color impression of the glass.

The glass of comparative example C1 showed a yellow tint.

Resistance to hydrolysis

Table 2 shows the results of hydrolysis resistance test according to USP660 (glass granules). Briefly, glass particles were treated according to USP660 glass particle test. Analyzing the eluate by flame atomic absorption spectroscopy (F-AAS) to obtain Na₂O、K₂O, MgO and CaO value (mg/l). Obtaining Na₂The O equivalent value is taken as a weighted sum of these values. Based on Na₂Molecular weight of O and K₂O, MgO or the molecular weight ratio of CaO determines the contribution of the respective oxide to the weighted sum, respectively. For example, K₂The weighting factor for O is calculated as follows: m (Na)₂O)/M(K₂O)＝[61.979/(2*39.098+15.999)]＝0.658)。

In DIN ISO 4802-2: 2017. Obtaining Na₂O equivalent value as Na obtained₂Value of O and K₂O, MgO and CaO.

All values can be easily converted from mg/l to μ g/g to determine the percentage of defined type I USP 660. Briefly, the defined type I of USP660 corresponds to 62. mu.g Na per gram of glass particles₂And (3) O equivalent. For example, 53.28. mu.g Na per gram of glass particles₂The value of O equivalent corresponds to about 86% of type I as defined by USP 660.

TABLE 2

Composition (I)	E1	E3	C1	C2	C3
						Na2O[mg/l]	7.2	6.7	8.08	7.80	16.08
K2O[mg/l]	0.42	0.53	0.49	0.53	0.05
						MgO[mg/l]	0.08	0.10	-	0.10	0.22
CaO[mg/l]	1.9	1.93	2.04	2.00	0.23
						Na2O equivalent/gram particles [ mg/l]	9.70	9.34	10.66	10.51	16.71
Na2O[μg/g]	36.00	33.50	40.40	39.00	80.40
						K2O[μg/g]	2.10	2.65	2.45	2.65	0.23
MgO[μg/g]	0.40	0.50	0.00	0.50	1.12
						CaO[μg/g]	9.50	9.65	10.20	10.00	1.16
Na2O equivalent/gram particles [ mu.g/g]	48.49	46.68	53.28	52.56	83.55
						Define type I (according to USP 660).)	78％	75％	86％	85％	135％

The percentage stated at … indicates that this value corresponds to the consumption of 0.02N HCl per gram of glass particles reaching the limit of 0.10 ml. It is noteworthy that, as mentioned above, the corresponding type I of definition also corresponds to 62. mu.g Na per gram of glass particles₂And (3) O equivalent.

The hydrolysis resistance of E2 is comparable to that of E1.

The results show that the glasses according to the invention have a hydrolysis resistance class I (type I according to USP 660/glass granules). In fact, the hydrolysis resistance of the glasses of the invention is better compared to the comparative examples, since E1 to E3 achieve hydrolysis resistance corresponding to less than 80% of defined type I. In contrast, the comparative example does not achieve such a value. C1 to C3 have hydrolysis resistances corresponding to more than 80% of the defined type I. The hydrolysis resistance of C3 is even 135% of the defined type I, thus according to USP660, only type II.

In conclusion, the glass according to the invention has a better hydrolysis resistance than the comparative example.

Chemical tempering

Chemical tempering in KNO₃At 450 ℃ for different time spans. The results are shown in Table 3 below.

TABLE 3

As described above, the threshold diffusivity, D, can be calculated from DoL and the chemical strengthening time, t, according to the following formula: 1.4 sqrt (4D t). In this disclosure, these are given in KNO₃D chemically strengthened at 450 ℃ for 9 hours.

Based on this, the threshold diffusivity D of E2 and E3 can be calculatedIs about 22.7 μm²H is used as the reference value. The threshold diffusivity of C1 was about 44.4 μm²H, threshold diffusivity of C2 of about 14.5 μm²H, threshold diffusivity of C3 of about 32.7 μm²/h。

Therefore, the glass of the present invention is very suitable for chemical tempering.

Optical Properties

Exemplary glasses E1 through E3 had refractive indices of 1.513. The refractive index of C1 was 1.515, and the refractive index of C2 was 1.516.

The optical properties of glass tubes with a wall thickness of 1mm or 10mm were determined. Thus, the sample thickness was 1mm or 10mm, respectively. In particular, the transmittance was determined at a wavelength of 400nm, a wavelength of 495nm, and a wavelength of 670 nm. The x and y values of the CIE 1931 color space were determined according to DIN 5033. The results are shown in table 4 below. Samples were measured in duplicate. The average values are shown in table 4.

TABLE 4

The color positions of glasses E2, E3, and C1 in the CIE 1931 color space are shown in fig. 1.

The data show that comparative example C1 has unfavorable color locations with high x and y values, especially at a sample thickness of 10 mm. In particular, very favorable x values of less than 0.311 and very favorable y values of less than 0.318 can be achieved exclusively by means of the glasses according to the invention.

Thus, the glass of the present invention has very good optical properties.

Devitrification

Devitrification resistance may be in accordance with KG_maxAnd (4) showing. KG_maxThe lower the devitrification resistance, the higher. KG_maxMeans the maximum crystallization rate in μm/min. The measurement of crystallization rate is well known. The crystallization rate is measured along the formed crystals, i.e. in the direction of their largest dimension.

Briefly, the crystallization rate was determined by heat-treating the glass in a gradient furnace at elevated temperature for 60 minutes. Importantly, if no devitrification occurs at all during the gradient reinforcement, thenInability to determine KG_max。

The crystallization rate was determined using glass particles with a diameter of 1.6mm to 4 mm. The glass particles were gradient strengthened on a platinum support. The carrier has recesses each for receiving a glass particle, with a hole at the bottom of each recess for optical inspection, so that the crystallization rate is determined by microscopy. Each recess was 4mm in diameter and each hole was 1mm in diameter.

No devitrification of the exemplary glass E3 was detected at temperatures ranging from 1060 ℃ to 1185 ℃. No devitrification of the glasses E1, E2 and C2 was detected in the temperature range of 1100 ℃ to 1395 ℃. In contrast, comparative example C1 devitrified (KG) in the temperature range of 1100 ℃ to 1395 ℃_max＝0.01μm/min)。

Thus, the glass of the present invention has very good resistance to devitrification.