A lead-free crystalline glass composition

Abstract

The invention relates to a lead-free crystalline glass having a refractive index higher than 1,52 and a specific gravity of at least 2,54 g / cm3. The crystalline glass comprises, by weight percentage, 65-72% SiO2, 0, 1-3,5% AI2 O3, 5-11% CaO, 10-15% Na2O, and the sum of the weight percentages of K2O, BaO, and ZnO is more than 10%, and the sum of the weight percentages of K2O and ZnO is less than 9%.

Description

[0001] SPECIFICATION

[0002] A LEAD-FREE CRYSTALLINE GLASS COMPOSITION

[0003] TECHNICAL FIELD

[0004] The present invention relates to a lead-free crystalline glass composition intended for use in household glassware products.

[0005] STATE OF THE ART

[0006] Glass is chemically recognized as an inert and durable material; however, certain special conditions deviate from this general perception. One example is the interaction of glass with water. Particularly at elevated temperatures, the effect of water on glass can produce significant results. In the absence of strongly acidic or basic solutions, corrosion rates at normal temperatures remain very low, with corrosion occurring only over extended periods. In addition to water-induced corrosion, fluoride compounds (HF) can severely affect glass surfaces. When exposed to water, the glass surface forms a gel-like layer containing silanol (Si— OH) groups. The solubility of this gel-like layer in water is very low. When the glass surface is exposed to water, moisture, or dew, Si-OH groups are formed as a result of the ion exchange reaction occurring between network modifiers such as Na+, K+ (alkali ions) and Ca+2, Mg+2 (alkaline earth ions) present in the glass structure and the H+ ions of water, and the network modifiers move out of the glass structure. A cloudy appearance emerges on the surface. This process is called atmospheric corrosion.

[0007] The effect of aqueous solutions on the glass surface is largely dependent on temperature. An example of this is the corrosion of household glassware in the strongly basic and high temperature washing environment (detergent solutions) of dishwashers.

[0008] EP0547263B1 relates to a lead-free zinc silicate crystal glass having a refractive index of > / = 1,52 and a composition, in % by weight based on oxide, of 65,0-70,0 of SiO2 6, 0-9,0 of CaO 4,0-12,0 of K2O 4,0-12,0 of Na2O 0,5-5, 0 of B2O3 4, 0-7,0 of ZnO 0, 1-1,0 of Sb2O3 and 1, 0-6,0 of ZrO2 and / or TIO2 with the proviso that the total amount of oxide constituents is 100% by weight, and to the use thereof for the production of domestic and table glassware.

[0009] BRIEF DESCRIPTION OF THE INVENTION

[0010] The object of the present invention is to provide a chemical composition for household glassware products with improved protection.

[0011] In order to achieve the aforementioned object, the invention relates to a lead-free crystalline glass having a refractive index higher than 1,52 and a specific gravity of at least 2,45 g / cm3. The crystalline glass comprises, by weight percentage, 65-72% SiO2, 0, 1-3,5% AI2O3, 5-11% CaO, 10- 15% Na2O, and the sum of the weight percentages of K2O, BaO, and ZnO is 10% or more, and the sum of the weight percentages of K2O and ZnO is less than 9%. Thus, the crystalline glass does not contain toxic lead elements, achieving desired properties. The obtained refractive index value reaches a value higherthan 1,52. When the obtained crystalline glass is examined according to ISO-719, it has been determined to possess high chemical resistance. Furthermore, it has been determined to exhibit high chemical resistance against detergents according to DIN10511. Additionally, the obtained crystalline glass can be produced by hand manufacturing.

[0012] In a preferred embodiment of the invention, the weight percentage of K2O is in the range of 3% to 6,5%. Thus, the use of potassium oxide reduces the viscosity and crystallization tendency of the crystalline glass, lowering the melting and forming temperature of the glass, while increasing the thermal expansion coefficient.

[0013] In a preferred embodiment of the invention, the weight percentage of BaO is in the range of 3% to 7%. Thus, the use of barium oxide, as it binds to the network structure with double bonds, enables the reduction of the diffusion rate of Na+, thereby increasing the chemical resistance of the crystalline glass.

[0014] In a preferred embodiment of the invention, the weight percentage of ZnO is in the range of 0,01% to 3%. Thereby, the use of zinc oxide modifies the network structure, ensuring an increase in chemical resistance. ZnO, unlike other +2 valence oxides, can improve chemical resistance without increasing the thermal expansion coefficient. It also increases the density and refractive index of the glass.

[0015] In a preferred embodiment of the invention, the weight percentage of AI2O3 is in the range of 0,2% to 2%. Thereby, since AI2O3 can take part in the formed silica network structure, it forms strong bonds and therefore raises the melting temperature of the glass. It also increases chemical resistance and provides a positive contribution to the chemical tempering process.

[0016] In a preferred embodiment of the invention, the weight, percentage of CaO is in the range of 6% to 9%. Thereby, the use of calcium oxide ensures an increase in the refractive index. Furthermore, the use of calcium oxide has a positive effect on the crystalline glass in terms of chemical resistance and mechanical strength. The calcium oxide level has been adjusted appropriately for hand manufacturing, considering the forming range / temperature and crystallization temperature.

[0017] In a preferred embodiment of the invention, the weight percentage of Na2O is in the range of 10% to 13%. Thus, the use of sodium oxide, as it binds to the network structure with a single weak bond, results in high mobility within the glass and acts to decrease the viscosity of the glass.

[0018] In a preferred embodiment of the invention, the weight percentage of Fe2O3 is in the range of 0,005% to 0,020%.

[0019] In a preferred embodiment of the invention, the weight percentage of TiO2 is in the range of 0% to 1%. Thereby, the use of titanium oxide helps increase the refractive index and chemical resistance of the glass and lower the liquidus temperature.

[0020] In a preferred embodiment of the invention, the weight percentage of MgO is in the range of 0,01% to 0,2%. Thus, the use of magnesium oxide increases chemical resistance.

[0021] In a preferred embodiment of the invention, the weight percentage of SO3 is in the range of 0,2% to 0,7%. Thereby, fining of the crystalline glass is ensured.

[0022] In a preferred embodiment of the invention, the weight percentage of Sb2O3 is in the range of 0% to 0,5%. Thereby, the use of antimony oxide performs the decolorization process by oxidizing the iron Fe2+ Fe3+) within the crystalline glass. In the presence of alkali and at high temperature, pentavalent antimony is reduced to trivalent antimony as per the equation, releasing oxygen and oxidizing iron to Fe+3. It also aids in fining.

[0023] In a preferred embodiment of the invention, the weight percentage of Er2O3 is in the range of 0,01% to 0,05%. Thereby, physical decolorization of the crystalline glass is ensured.

[0024] In a preferred embodiment of the invention, the weight percentage of B2O3 is in the range of 0% to 2%. Thereby, the use of boron oxide, while being an oxide that improves hydrolytic resistance, also lowers the viscosity of the glass, enabling easier melting.

[0025] In a preferred embodiment of the invention, the thermal expansion coefficient is in the range of 85-105. Thereby, it is ensured that the structural integrity of the crystalline glass is not compromised despite sudden temperature changes.

[0026] BRIEF DESCRIPTION OF THE FIGURES

[0027] Figure 1 shows the viscosity-temperature graph for 14 different example compositions.

[0028] Figure 2 shows the density graph of 14 different example compositions.

[0029] Figure 3 shows the refractive index graph of 14 different example compositions.

[0030] Figure 4 shows the thermal expansion coefficient graph of 14 different example compositions.

[0031] Figure 5 shows the chemical resistance graph determined according to the ISO719 method for 14 different example compositions.

[0032] DETAILED DESCRIPTION OF THE INVENTION

[0033] In this detailed description, the inventive development is described with references to examples solely for better illustration of the subject matter, without any limitation. To obtain a lead-free crystalline glass, a glass composition batch is used. By weight percentages, the crystalline glass comprises 65-72% SiO2, 0, 1-3,5% AI2O3, 5-11% CaO, 10-15% Na2O, and other additives. Furthermore, the sum of the weight percentages of K2O, BaO, and ZnO is 10% or more.

[0034] The use of BaO and CaO together with ZnO are also oxides that act to increase the refractive index. CaO also provides improvement in terms of chemical resistance and mechanical strength. The selected CaO level is also adjusted appropriately for hand manufacturing, considering the forming range / temperature and crystallization temperature.

[0035] B2O3, while being an oxide that improves hydrolytic resistance, also facilitates melting by lowering the viscosity of the glass. For this reason, the composition is designed to comprise or not comprise a certain amount of B2O3.

[0036] AI2O3 will contribute to the improvement of chemical resistance and corrosion resistance. On the other hand, if used excessively, it will cause an increase in the melting temperature of the glass. Therefore, its use in the specified proportions is foreseen.

[0037] For the fining and / or decolorization of the glass, oxides such as NaCI, CeO2, Na2SO4, As2O3, and Sb2O3 can be used.

[0038] Sb2O3 performs the decolorization process by oxidizing iron (Fe2+ ~>Fe3+). In the presence of alkali and at high temperature, pentavalent antimony is reduced to trivalent antimony as shown in equations 1 and 2, releasing oxygen and oxidizing iron to Fe+3. It also aids in fining.

[0039] Sb2O5 -> Sb2O3 +02. (1)

[0040] Sb2O5+ 4FeO -> Sb2O3 +2 Fe2O3. (2)

[0041] After the iron present in the batch is oxidized to Fe+3, the yellow-green color imparted by Fe+3 is physically masked by complementary coloring oxides such as Mn, Se, Ni, Co, Er.

[0042] CeO2, another preferred oxide for fining and decolorization, has not been added to the composition because its use above a certain proportion causes solarization. Alkali oxides such as Na2O, K2O, being attached to the network structure by a single weak bond, have high mobility within the glass and act to decrease the viscosity and chemical resistance of the glass. With the addition of Na20 and K2O to the composition, the reaction rate between water and glass accelerates, and the chemical resistance of the glass decreases. The chemical resistance of glass comprising both Na20 and K2O is greater than the chemical resistance of glass comprising only one of Na2O and K2O in the same total amount. Alkaline earth oxides such as CaO, MgO, BaO, by binding to the network structure with double bonds, reduce the diffusion rate of alkali oxides and thus increase chemical stability.

[0043]

[0044] In the tables above, the weight percentages of the materials used for the crystalline glass composition are shown. In the tables, chemical resistance, climatic resistance, and dishwasher resistance are indicated by numbers ranging from 1 to 5. Number 1 means the best, number 2 means good, number 3 means moderate, number 4 means poor, and number 5 means the worst. logr) = 2 (Poise): This expression indicates that the viscosity is 100 Poise. logr) = 3 (Poise): This expression indicates that the viscosity is 1000 Poise. logr) = 7,65 (Poise): This expression indicates that the viscosity is approximately 10A7,65 Poise.

[0045] Example 1 shown in Table 1 comprises, by weight percentages, 69,70% SiO2, 0,29% AI2O3, 0,008% Fe2O3, 0,017% TiO2, 6,94% CaO, 0,04% MgO, 11,52% Na2O, 4,99% K2O, 0,32% SO3, 3,43% BaO, 1,83% ZnO, 0,131% Sb2O3, 0,034% Er2O3, and 0,75% B2O3. The temperature at logq-2 viscosity value for the crystalline glass having the composition of Example 1 was determined as 1428°C, the temperature at logr|=3 (Poise) value as 1167°C, and the temperature at logp-7,65 (Poise) value as 698°C. The crystalline glass having the composition of Example 1 has a specific gravity value of 2,561 g / cm3. The crystalline glass having the composition of Example 1 has a thermal expansion coefficient of 96,64 and a refractive index of 1,52. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 4. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 1 was numbered as 5. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 5. Its chemical resistance (according to ISO 719) was determined as 0,87 ml 0,01 mol / L H Cl / g powder glass.

[0046] Example 2 shown in Table 1 comprises, by weight percentages, 70,47% SiO2, 0,7% AI2O3, 0,009% Fe2O3, 0,021% TiO2, 6,75% CaO, 0,03% MgO, 10,09% Na 20, 4,59% K2O, 0,42% SO3, 4,15% BaO, 1,36% ZnO, 0,14% Sb2O3, 0,033% Er2O3, and 0,43% B2O3. The temperature at logri-2 viscosity value for the crystalline glass having the composition of Example 2 was determined as 1460!,C, the temperature at logr|-3 (Poise) value as 1192°C, and the temperature at lc-gn~7,65 (Poise) value as 708°C. The crystalline glass having the composition of Example 2 has a specific gravity value of 2,564 g / cm3. The crystalline glass having the composition of Example 2 has a thermal expansion coefficient of 96,81 and a refractive index of 1,52. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 2 was numbered as 3. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 3. Its chemical resistance (according to ISO 719) was determined as 0,66 ml 0,01 mol / L HCI / g powder glass.

[0047] Example 3 shown in Table 1 comprises, by weight percentages, 69,97% SIO2, 0,9% AI2O3, 0,008% Fe2O3, 0,021% TiO2, 6,67% CaO, 0,03% MgO, 11,24% Na2O, 4,67% K2O, 0,4% SO3, 4,1% BaO, 1,37% ZnO, 0,14% Sb2O3, 0,034% Er2O3, and 0,38% B2O3. The temperature at lo n-2 viscosity value for the crystalline glass having the composition of Example 2 was determined as 1456°C, the temperature at logq~3 (Poise) value as 1188°C, and the temperature at logp-7,65 (Poise) value as 706°C. The crystalline glass having the composition of Example 3 has a specific gravity value of 2,565 g / cm3. The crystalline glass having the composition of Example 3 has a thermal expansion coefficient of 97,15 and a refractive index of 1,52. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 3 was numbered as 3. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 1. Its chemical resistance (according to ISO 719) was determined as 0,69 ml 0,01 mol / L HCI / g powder glass.

[0048] Example 4 shown in Table 1 comprises, by weight percentages, 69,37% SIO2, 1,47% AI2O3, 0,01% Fe2O3, 0,02% TIO2, 6,48% CaO, 0,03% MgO, 11,48% Na2O, 4,66% K2O, 0,42% SO3, 4,09% BaO, 1,41% ZnO, 0,15% Sb2O3, 0,034% Er2O3, and 0,38% B2O3. The temperature at logq-2 viscosity value for the crystalline glass having the composition of Example 4 was determined as 1458°C, the temperature at logq-3 (Poise) value as 1189°C, and the temperature at lc-gn~7,65 (Poise) value as 705°C. The crystalline glass having the composition of Example 4 has a specific gravity value of 2,567 g / cm3. The crystalline glass having the composition of Example 4 has a thermal expansion coefficient of 98,33 and a refractive index of 1,52. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 4 was numbered as 1. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 1. Its chemical resistance (according to ISO 719) was determined as 0,62 ml 0,01 mol / L HCI / g powder glass.

[0049] Example 5 shown in Table 1 comprises, by weight percentages, 70,01% SiO2, 0,96% AI2O3, 0,008% Fe2O3, 0,02% TiO2, 6,51% CaO, 0,03% MgO, 11,03% Na2O, 5,08% K2O, 0,42% SO3, 3,98% BaO, 1,38% ZnO, 0,15% Sb2O3, 0,033% Er2O3, and 0,39% B2O3. The temperature at logr| 2 viscosity value for the crystalline glass having the composition of Example 4 was determined as 1460°C, the temperature at log -3 (Poise) value as 1191!’C, and the temperature at logq-7,65 (Poise) value as 706!’C. The crystalline glass having the composition of Example 5 has a specific gravity value of 2,558 g / cm3. The crystalline glass having the composition of Example 5 has a thermal expansion coefficient of 99,01 and a refractive index of 1,52. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 5 was numbered as 2. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 2. Its chemical resistance (according to ISO 719) was determined as 0,73 ml 0,01 mol / L HCI / g powder glass.

[0050] Example 6 shown in Table 2 comprises, by weight percentages, 69,9% SIO2, 0,95% AI2O3, 0,009% Fe2O3, 0,022% TiO2, 6,64% CaO, 0,03% MgO, 11,19% Na2O, 4,67% K2O, 0,42% SO3, 4,54% BaO, 0,97% ZnO, 0,15% Sb2O3, 0,033% Er2O3, and 0,48% B2O3. The temperature at logq-2 viscosity value for the crystalline glass having the composition of Example 6 was determined as 1455°C, the temperature at logr|-3 (Poise) value as 1187°C, and the temperature at lc-gn~7,65 (Poise) value as 705°C. The crystalline glass having the composition of Example 6 has a specific gravity value of 2,566 g / cm3. The crystalline glass having the composition of Example 6 has a thermal expansion coefficient of 98,48 and a refractive index of 1,5203. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 6 was numbered as 4. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 4. Its chemical resistance (according to ISO 719) was determined as 0,82 ml 0,01 mol / L HCI / g powder glass.

[0051] Example 7 shown in Table 2 comprises, by weight percentages, 70,03% SIO2, 0,94% AI2O3, 0,009% Fe2O3, 0,023% TiO2, 6,63% CaO, 0,03% MgO, 11,07% Na2O, 5,07% K2O, 0,43% SO3, 4,64% BaO, 0,51% ZnO, 0,160% Sb2O3, 0,033% Er2O3, and 0,43% B2O3. The temperature at logrj=2 viscosity value for the crystalline glass having the composition of Example 7 was determined as 1458°C, the temperature at logp-3 (Poise) value as 1189°C, and the temperature at logp-7,65 (Poise) value as 705°C. The crystalline glass having the composition of Example 7 has a specific gravity value of 2,562 g / cm3. The crystalline glass having the composition of Example 7 has a thermal expansion coefficient of 99,07 and a refractive index of 1,5200, The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Its chemical resistance was numbered as 3 on Table 2. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 7 was numbered as 5. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 5. Its chemical resistance (according to ISO 719) was determined as 0,73 ml 0,01 mol / L HCI / g powder glass.

[0052] Example 8 shown in Table 2 comprises, by weight percentages, 70,28% SiO2, 0,94% AI2O3, 0,007% Fe2O3, 0,023% TIO2, 6,56% CaO, 0,03% MgO, 10,8% Na2O, 5,22% K2O, 0,43% SO3, 5,03% BaO, 0,05% ZnO, 0,15% Sb2O3, 0,033% Er2O3, and 0,45% B2O3. The temperature at logr| 2 viscosity value for the crystalline glass having the composition of Example 8 was determined as 1464°C, the temperature at Iogr 3 (Poise) value as 1193°C, and the temperature at logq-7,65 (Poise) value as 706°C. The crystalline glass having the composition of Example 8 has a specific gravity value of 2,563 g / cm3. The crystalline glass having the composition of Example 8 has a thermal expansion coefficient of 99,98 and a refractive index of 1,5203. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Its chemical resistance was numbered as 3 on Table 2. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 8 was numbered as 5. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 5. Its chemical resistance (according to ISO 719) was determined as 0,79 ml 0,01 mol / L HCI / g powder glass.

[0053] Example 9 shown in Table 2 comprises, by weight percentages, 67,64% SIO2, 1,58% AI2O3, 0,015% Fe2O3, 0,026% TiO2, 6,47% CaO, 0,041% MgO, 12,41% Na2O, 5,07% K2O, 0,41% SO3, 4,05% BaO, 1,41% ZnO, 0,146% Sb2O3, 0,035% Er2O3, and 0,7% B2O3. The temperature at logr 2 viscosity value for the crystalline glass having the composition of Example 9 was determined as 1421°C, the temperature at logn 3 (Poise) value as 1159°C, and the temperature at logn~7,65 (Poise) value as 692°C. The crystalline glass having the composition of Example 9 has a specific gravity value of 2,576 g / cm3. The crystalline glass having the composition of Example 9 has a thermal expansion coefficient of 100 and a refractive index of 1,5203. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 9 was numbered as 2. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 3. Its chemical resistance (according to ISO 719) was determined as 0,78 ml 0,01 mol / L HCI / g powder glass.

[0054] Example 10 shown in Table 2 comprises, by weight percentages, 68,75% SIO2, 1,86% AI2O3, 0,016% Fe2O3, 0% TiO2, 6,84% CaO, 0,04% MgO, 11,02% Na2O, 4,9% K2O, 0,4% SO3, 4,25% BaO, 0,89% ZnO, 0,159% Sb2O3, 0,031% Er2O3, and 0,84% B2O3. The temperature at Iogr 2 viscosity vaiue for the crystalline giass having the composition of Exampie 10 was determined as 1451°C, the temperature at Iogr 3 (Poise) vaiue as 1185°C, and the temperature at logrp-7,65 (Poise) value as 708°C. The crystalline glass having the composition of Example 10 has a specific gravity value of 2,556 g / cm3. The crystalline glass having the composition of Example 10 has a thermal expansion coefficient of 97,8 and a refractive index of 1,52. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 10 was numbered as 1. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 2. Its chemical resistance (according to ISO 719) was determined as 0,74 ml 0,01 mol / L HO / g powder glass.

[0055] Example 11 shown in Table 3 comprises, by weight percentages, 69,54% SiO2, 0,72% AI2O3, 0,009% Fe2O3, 0% TIO2, 6,78% CaO, 0,04% MgO, 11,36% Na2O, 4,89% K2O, 0,34% SO3, 3,8% BaO, 1,67% ZnO, 0,123% Sb2O3, 0,032% Er2O3, and 0,7% B2O3. The temperature at logq-2 viscosity value for the crystalline glass having the composition of Example 11 was determined as 1438°C, the temperature at Iogr 3 (Poise) value as 1174°C, and the temperature at iogr 7,65 (Poise) value as 701°C. The crystalline glass having the composition of Example 11 has a specific gravity value of 2,565 g / cm3. The crystalline glass having the composition of Example 11 has a thermal expansion coefficient of 98,3 and a refractive index of 1,5211. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 11 was numbered as 2. Its chemical resistance (according to ISO 719) was determined as 0,67 ml 0,01 mol / L HCI / g powder glass.

[0056] Example 12 shown in Table 3 comprises, by weight percentages, 69,47% SIO2, 0,94% AI2O3, 0,009% Fe2O3, 0% TIO2, 6,7% CaO, 0,04% MgO, 11,36% Na2O, 4,78% K2O, 0,33% SO3, 3,91% BaO, 1,61% ZnO, 0,120% Sb2O3, 0,032% Er2O3, and 0,70% B2O3. The temperature at logr|=2 viscosity vaiue for the crystalline glass having the composition of Example 12 was determined as 1442°C, the temperature at Iogr 3 (Poise) value as 1178°C, and the temperature at iogr 7,65 (Poise) value as 703°C. The crystalline glass having the composition of Example 12 has a specific gravity value of 2,563 g / cm3. The crystalline glass having the composition of Example 12 has a thermal expansion coefficient of 98,1 and a refractive index of 1,5200, The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 12 was numbered as 1. Its chemical resistance (according to ISO 719) was determined as 0,75 ml 0,01 mol / L HCI / g powder glass.

[0057] Example 13 shown in Table 3 comprises, by weight percentages, 69,45% SIO2, 1,19% AI2O3, 0,009% Fe2O3, 0% TiO2, 6,58% CaO, 0,03% MgO, 11,34% Na2O, 4,73% K2O, 0,33% SO3, 3,97% BaO, 1,52% ZnO, 0,123% Sb2O3, 0,032% Er2O3, and 0,7% B2O3. The temperature at logr|=:2 viscosity value for the crystalline glass having the composition of Example 13 was determined as 1448°C, the temperature at logrj-3 (Poise) value as 1182!’C, and the temperature at logq-7,65 (Poise) value as 704°C. The crystalline glass having the composition of Example 13 has a specific gravity value of 2,558 g / cm3. The crystalline glass having the composition of Example 13 has a thermal expansion coefficient of 98,9 and a refractive index of 1,521. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 13 was numbered as 1. Its chemical resistance (according to ISO 719) was determined as 0,7 ml 0,01 mol / L HCI / g powder glass.

[0058] Example 14 shown in Table 3 comprises, by weight percentages, 69,33% SIO2, 1,45% AI2O3, 0,009% Fe2O3, 0% TIO2, 6,47% CaO, 0,03% MgO, 11,35% Na2O, 4,62% K2O, 0,31% SO3, 4,13% BaO, 1,45% ZnO, 0,122% Sb2O3, 0,032% Er2O3, and 0,7% B2O3. The temperature at logn-2 viscosity value for the crystalline glass having the composition of Example 12 was determined as 1452°C, the temperature at logq=3 (Poise) value as 1185°C, and the temperature at Iogr 7,65 (Poise) value as 705°C. The crystalline glass having the composition of Example 14 has a specific gravity value of 2,557 g / cm3. The crystalline glass having the composition of Example 14 has a thermal expansion coefficient of 97,3 and a refractive index of 1,521. The hydrolytic resistance class of the crystalline glass according to ISO 719 was determined as 3. Climatic resistance is tested by keeping the crystalline glass under conditions of 50°C, 95% humidity for 14 days. The climatic resistance of the crystalline glass having the composition of Example 14 was numbered as 1. Dishwasher resistance was evaluated according to DIN10511 after 10,000 washes, and the dishwasher resistance was numbered as 1. Its chemical resistance (according to ISO 719) was determined as 0,67 ml 0,01 mol / L HCI / g powder glass.

[0059] The viscosity-temperature graph of the 14 different example compositions given above is shown in Figure 1, the density graph in Figure 2, the refractive index graph in Figure 3, the thermal expansion coefficient graph in Figure 4, and the chemical resistance graph in Figure 5.

[0060] Glass corrosion starts in the early stages with the formation of unconnected pits. These pits grow over time, connect with each other, and form larger and deeper formations called craters. As the craters grow and connect, the formation of a continuous, opaque corrosion layer is observed. Corrosion begins with the interaction occurring at the interface between the glass surface and its surrounding environment. In this interaction; the conditions of the surrounding environment (temperature, humidity, pH, duration) and the glass composition and surface properties are very important.

[0061] It occurs in two stages:

[0062] 1st stage corrosion reaction: When the glass surface is exposed to water, moisture, or dew, Si-OH groups are formed as a result of the ion-exchange reaction occurring between network modifiers such as Na+, K+ (alkali ions) and Ca+2, Mg+2 (alkaline earth ions) present in the glass structure and the H+ ions of water, and the network modifiers move out of the glass structure.

[0063] The reactions are as follows:

[0064] (= Si-O-M+)glass + H2O -> (= Si-OH)glass + M+OH-

[0065] (= Si-O- M+2 -O-Si )glass + 2H2O -> 2(= Si-OH)glass + M+2 + 2OH- (1)

[0066] As a result of these reactions, a hydrated glass surface poor (leached) in alkali and alkaline earth ions is formed. Depending on the chemical composition of the glass, the leaching process gradually slows down and stops at a certain stage. At this stage, the network components remain unchanged.

[0067] 2nd stage corrosion reaction: As the ion-exchange reaction progresses, the pH of the glass surface or the aqueous solution in contact with the surface may rise above 9. With the increase in pH, more alkali dissolution occurs. As long as the exposure to moisture or vapor continues, the ion exchange reactions proceed repeatedly, and when the pH value exceeds 9, hydroxyl (OH-) ions attack the Si-O-Si bonds belonging to the network structure, and the silica network structure disintegrates. The reaction is as follows:

[0068] (= Si-O-Si= )glass + OH- -> (= Si-OH)glass + -O-Si

[0069] When the amounts of alkali oxides Na2O and K2O, especially the amount of Na2O, are increased in a glass composition, the reaction between water and glass accelerates, and the chemical resistance decreases. Despite this, the chemical resistance of glass comprising equal amounts of Na2O and K2O is greater than the chemical resistance of glass comprising the same total amount but only one of Na2O or K2O (mixed alkali effect).

[0070] Alkaline earth oxides such as CaO, MgO, BaO increase chemical resistance by binding to the network structure with double bonds, thereby reducing the diffusion rate of Na+. Although CaO and MgO affect glass properties in the same direction, there are some fundamental differences in the placement of these elements in the network structure. Ca+2 forms a triplet group in group HA, differing especially from Mg+2, along with Sr+2 and Ba+2 which follow it. Ca+2 forms quite strong bonds in the glass structure. Although its ionic radius is close to that of Na+, the double valence of Ca+2 allows it to bind more tightly to the network structure. On the other hand, Mg+2, unlike the elements in its group, forms bonds with a more covalent character. Due to its small radius, it has a polarizing effect on oxygen.

[0071] The dissolution of the silica network structure occurs at high pH and depends on the exposure of the glass network to OH- ions. While tetrahedral silicate is neutral, AI2O3 regions are negatively charged. When the glass structure is exposed to OH- ions, they are repelled by the negatively charged AI2O3 areas. Therefore, AI2O3 increases chemical resistance.

[0072] Glass is generally considered a chemically stable material under normal conditions. However, during the washing process in a dishwasher, the surface of household glassware is attacked by detergent-containing water solutions and steam at high temperatures for varying durations. As a result of this interaction between the glass and the environment, different types of irreversible glass surface damage such as hazing, milky appearance / white layer formation, loss of brilliance, iridescence, and linear defects can occur on the products. The appearance of the surface damage depends on the type of corrosion reaction, which is related to the composition of the glass, and the pH and temperature of the solution it is exposed to. The environment, created during dishwasher washing, comprising water, water vapor, detergent chemicals, and rinse aid chemicals, represents an aggressive environment for glass. Depending also on temperature and time parameters, a comprehensive literature review was conducted to reveal the details and mechanisms of the corrosion behavior of glass in this described environment, and some important findings are summarized below;

[0073] In an exemplary study, iridescence is a common phenomenon that occurs in household glassware exposed to strong detergent solutions (bases) of the type used in domestic dishwashers or commercial dishwashers in food service facilities. It is believed that the underlying mechanism for the formation and development of iridescence is due to leaching occurring on the glass surface. In this mechanism, the attacking solution selectively dissolves certain components of the glass, leaving behind a porous network of material (in commercial silicate glasses, the network structure will be rich in silica), resulting in the formation of layers with different thicknesses and refractive indices. These layers with different physical properties lead to the formation of blue, purple, and yellow colors that cause the distinct iridescence appearance upon reflection of incident light. Many factors contribute to the initiation and degree of chemical attack to which the glass is exposed. In the case of detergent solutions, important factors affecting the formation of leaching, including the type and concentration of anions in the solution, the temperature, and the pH of the solution, must be considered. Among the most relevant anions encountered in commercially marketed detergents are phosphates, polyphosphates, various soluble silicates, carbonates, and bicarbonates. Since the type of detergent to which the glass will be exposed is unknown, glassware intended for use in food service applications must be resistant to all these anions. In another study, an aging study conducted on crystalline goblets, handmade and machine-made goblets were aged for 3 months under conditions of 60°C and 90% relative humidity. A quantitative assessment of corrosion was made by evaluating the increase in surface roughness, and no significant difference was found between the degradation behaviors of handmade and machine-made products. According to the results of a study examining the effect of MgO and AI2O3 amounts in soda-lime glass composition on glass corrosion using the ISO 719 test and a humidity chamber, increased MgO and AI2O3 contents in the composition enhance the corrosion resistance and storage life of the product.

[0074] In an exemplary study, among glass products with different compositions tested by washing in a humidity chamber and dishwasher for up to 3000 cycles, compositions comprising AI2O3 and ZnO were found to be more resistant to aging tests and dishwasher washing.

[0075] In another example study, it was determined that different types of degradation occurred in the rim and body parts of goblets tested in detergent concentrations prepared to contain Na5P3O10, NaOH, Na2SO4, and varying ratios of Na2O5SI2. It was stated that the concentration of Na2O5SI2 in the solution plays a decisive role in the corrosion mechanism, with corrosion progressing faster at lower concentrations. The rim area of the goblets formed an aluminum-rich film with a different refractive index than the rest of the goblet after washing, causing an iridescent appearance. Micro-scratches / grooves formed during production in the widest part of the bowl (body) were identified as regions more prone to inhomogeneous corrosion, leading to the formation of hazy rings.

Claims

CLAIMS1 . A lead-free crystalline glass having a refractive index higher than 1,52 and a specific gravity of at least 2,54 g / cm3, characterized by comprising, by weight percentage: 65-72% SiO2, 0,1- 3,5% AI2 03, 5-11% CaO, 10-15% Na2O and the sum of the weight percentages of K2O, BaO, and ZnO being more than 10%, and the sum of the weight, percentages of K2O and ZnO being less than 9%.

2. A crystalline glass according to claim 1, wherein the weight percentage of K2O is in the range of 3% to 7,5%.

3. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of BaO is in the range of 3% to 7%.

4. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of ZnO is in the range of 0% to 3%.

5. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of AI2O3 is in the range of 0,2% to 2%.

6. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of CaO is in the range of 6% to 9%.

7. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of Na2O is in the range of 10% to 13%.

8. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of Fe2O3 is in the range of 0,001% to 0,04%.

9. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of TiO2 is in the range of 0% to 1%.

10. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of MgO is in the range of 0,01% to 0,2%.

11. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of SO3 is in the range of 0,2% to 0,7%.

12. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of Sb2O3 is in the range of 0% to 4%.

13. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of Er2O3 is in the range of 0,01% to 0,05%.

14. A crystalline glass according to any one of the preceding claims, wherein the weight percentage of B2O3 is in the range of 0% to 4%.

15. A crystalline glass according to any one of the preceding claims, wherein the thermal expansion coefficient is in the range of 90-100.

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