SK277737B6 - Leadless crystal glass - Google Patents

Abstract

Leadless crystal glass suitable for hand and machine production of utility glass ware especially luxurious character glass with high refractive index, contains in per cent weight 50 to 65 of silicon dioxide SiO/sub_2, 0,1 to 10 of aluminium oxide Al/sub_2/O/sub_3, 0,5 to 17 of zirconium oxide ZrO/sub_ 2, 10 to 22 of potassium oxide K/sub_ 2/O and/or sodium oxide Na/sub_2/O, 2 to 10 of calcium oxide CaO and/or magnesium oxide MgO, at which the content of iron oxide Fe/sub_2/O/sub_3 is in range 0,01 to 0,025 per cent weight. Further it contains single or in combination 0,1 to 10 per cent weight of barium oxide BaO, zinc oxide ZnO, boron oxide B/sub_2/O/sub_3 and lithium oxide Li/sub_2/O and 0,1 to 1 per cent weight of antimony oxide Sb/sub_2/O/sub_3. Next modificators are single or in combination in range of trace to 1 per cent weight titanic oxide TiO/sub_2 and stannic oxide SnO/sub_2.

Description

Technical field

The invention relates to unleaded crystal glass, in particular intended for the manual and machine production of utility glass, with a refractive index of 1.53 to 1.58. The glass 5 comprises silica, alumina, zirconia, calcium and / or magnesium, potassium and / or sodium.

Background 10

The classification of crystal utility glasses according to ČSN 70 001 is as follows:

- sodium-potassium crystal, where Σ of potassium and calcium oxide is ž 10% by weight; %, refractive index at 15 of these glasses is not required

- crystal glass, where Σ of potassium, quartz and lead oxide is> 10% by weight; % with a refractive index of about 1.51

- special crystal glass, where Σ of potassium, zinc, quartz and lead oxide is> 10% by weight; %, with a refractive index of 1.51 to 1.525

- lead crystal, wherein the lead oxide content is > 24 wt. % with refractive index ä 1,545

- a highly lead crystal wherein the lead oxide content of 25 is > 30 wt. % and the refractive index is »1.545.

Sodium-potassium crystal glass is a Czech specialty. The remaining crystal types comply with the EEC Directives. The first two above-mentioned crystal glasses are used for so-called glass products. cheap crystal 30 glass, which is accentuated especially low price and refractive index is around 1.51.

Barium and lead oxide are used only by some manufacturers and in smaller quantities than eg. A. Smrček in the journal Sklár a keramik, 38 (1988), p. 286- 35

294. The group of special crystal glass already represents more noble products, in which the refractive index, which is to be around 1.52, is monitored, which is achieved by dosing barium, zinc oxide or possibly also in smaller quantities also lead oxide, 40 as mentioned e.g. . in German Patent No. 1987 no. 2839645, according to which such glass comprises in wt. %: silica 65 to 75, aluminum 0.1 to 2, calcium 2 to 12, magnesium 0 to 8, sodium 7 to 15, potassium 0 to 10, lithium 0 to 3, barium 1 to 6, zinc 0.2 The present invention, with its chemical composition, in addition to the titanium dioxide content, covers most of the crystal glasses produced, except for lead and high-grade crystal glass having a lead oxide content of > 24 wt. %. 50

For luxury products decorated mostly with grind, lead and high-lead crystal is used, which requires a refractive index> 1.545. Presently, the hygienic safety of the glasses is preferred, especially as regards the lead and barium content of the leachate. Given that these special crystal glasses achieve an increase in refractive index to the desired value by a predominantly increased content of barium and lead oxide, this hygiene requirement raises problems in the production of these glasses. 60

SUMMARY OF THE INVENTION

The above disadvantages are eliminated or substantially limits the crystal 65 with a zirconium oxide ZrO _2, of the present invention, which is characterized in that it comprises 50 to 65% by weight. of silica SiO _2, 0.1 to 10% by weight. % Al ₂ O ₃ , 0.5 to 17 wt. % ZrO ₂ , 10 to 22 wt. % K ₂ O and / or Na ₂ O, 2 to 10 wt. % CaO and / or MgO, 0.1 to 1 wt. antimony trioxide Sb ₂ O ₃ , the total iron content expressed as Fe ₂ O ₃ being in the range of 0.01 to 0.025% by weight. Furthermore, the glass comprises at least one oxide of the group consisting of barium oxide BaO, zinc ZnO, boron B ₂ % O ₃ and lithium Li ₂ O in an amount of 0.1 to 10 wt. barium oxide BaO, zinc oxide ZnO, boron oxide B ₂ O ₃ and lithium oxide Li ₂ O.

Preferably, the glass may contain, individually or in combination, traces of up to 1 wt. titanium dioxide TiO ₂ and tin SnO ₂ .

The advantage of this type of glass is comparable grindability and engraving with lead crystal, while the glass does not contain health and ecologically harmful lead oxide PbO. During its melting, environmentally harmful oxides of lead and arsenic, which are used in the production of lead crystal, do not escape. As it is lead-free glass, intended especially for utility glass, thus also as drinking and household glass, its advantage is that unwanted, harmful lead oxide PbO does not pass into the leachate. Compared to lead crystal glass, melting and blackening of these types of glass is easier because they have lower melting temperatures.

Additions of modifying additives, such as barium oxide, zinc ZnO, boron B ₂ O ₃ and lithium Li ₂ O, improve the melting point of the glass and liquidus in particular. Furthermore, these oxides also favorably influence the refractive index of the glass.

Antimony trioxide Sb ₂ O ₃ is preferred for glass blackening. Titanium dioxide TiO ₂ and stannous SnO ₂ as well as antimony trioxide Sb ₂ O ₃ also increase the refractive index.

DETAILED DESCRIPTION OF THE INVENTION

The invention is illustrated by the following examples.

Example no. 1 Glass splinters 2 content in « 3 4 silicon dioxide 60,185 58.31 61, 75 60.77 id hl and thread 5.00 12:38 5:00 5 .00 zirconium dioxide H 30 14.90 3:50 3:50 calcium oxide or, 0 (1 5.58 6:40 6.40 Vorečnucy oxide <1:40 sodium oxide t 2, 0 (1 19.87 7 .00 8 (10 potassium oxide H .00 fl. ? .5 6:00 6, <10 oxite) barium 8:00 night oxide H.00 people 2:00 2,110 <> · Itl antimony i th (1 50 0.29 t) 33 12:32 iron content expressed with no iron oxide (1,015 0.02 0.02 I '' £ oxides 100.00 100 .00 100.00 ÍUU.C'O log ETA-2 ^{[ C |} 15114 1405 1430 1408 'log ETA-4'^{> C |} U 14 1087 1012 1008 'log ΕΤΛ-7 65 ^{í> c} l 827 844 7 1 4 721 'ΕΤΛ-13 ^{l CI} 637 678 523 53 5 'log ΡΤΑΊ4.5 ^l ° ^C 602 647 489 501 r ¹ 'C l Ijquidua ¹ ' * 963 1210 930 950 Lonu index at 589.3 ma 1,545 72 i. 542 1. 543 density at ^{) l)} C | ^g «- ^J I 2,628 2,754 2,685 2,683 “7.0-300 l ^{lll <5 (:: 1 1} 9. 16 9:37 8.80 β.62 ohtusnasà [μπ.ηιίη ’) 0312 U, 343 O, 329 0372

Example # 5 6 7 Folders »kla Contents % hiruin XTI silicon dioxide 60,37 60.17 65.0 (1 aluminum oxide 7:00 3:00 1 .07 zirconium oxide 6.30 8.30 5:00 calcium oxide 6:00 6.00 6.40 sodium oxide 10:00 10:00 6.00 drumble oxide β, 00 8:00 6 .00 lithium oxide 2.00 2:00 C9 5,0U zinc oxide 3, 00 (boron ixide th 2:00 cixiil antimony (!, 31 12:32 0.31 trioxide t) 20 stannous oxide 0,2í) iron content expressed ox i dom that l «2i by s). 02 12:01 0, 02 £ ox i dov 100.00 100.00 100.00

^c : og ETA-2 (° C) 147.5 1518 1470 ^r log ETA-4 (C 1027 1 112 1040  ί og ΕΤΛ «7.65 (° C) 739 815 738 ETA-13 log [ ¹ 'C] 552nd 621 53'1 1 and ETA-14.5 [° C] 518 586 503 ^r 1 iquidH (C 970 950 H44 refractive index at 589.3 nm 1 .543 1,545 1. 544 density at 20 C (g.ca ^ 1) 2.5909 2.6206 2.6748 "20-300 C; ¹⁰ 6 ₍ at _r- l) 8.9 (1 7.93 8.68 abrasion [μη. min H 0.279 0192 0185

In the above embodiments, tiogETA = 2 corresponds to the melting point of the glass, ti? T? _{OgETA = 7 65} Littleton glass softening point temperature, t _{Oeta = 13} upper cooling temperature and _t | _og ETA = i4.s lower cooling temperature, and ₂₀ . ₃ c oo a mean coefficient of thermal expansion of the glass in the range of 20 to 300 ° C. grindability is reflected in the loss of the glass sample pm.min ^'1 to the diamond wheel with a particle size of 120 pm with a load of 1.71 g.mm ^"second

The melting temperature corresponding to the glass viscosity log ETA = 2 is about 1,500 ° C for lead glasses. In the glasses according to the invention it is either comparable, e.g. according to example no. 1 and no. 6, or lower by 30 ° C for the enamel according to Example no. 7, by 75 ° C for the enamel according to Example no. 5, by 92 ° C for the glass according to Example no. 4, by 70 ° C for the glass according to Example C. 3 and by 95 ° C for the glass according to Example no. Second

All liquidus temperatures except Ex. 2, where the zirconia content is high, are below the respective processing temperatures corresponding to the glass viscosity temperature log ETA = 4, so that the tendency to unwanted crystallization is suppressed in these glass melts.

For lead crystal, the refractive index is about 1.545, for glasses according to the invention it is in the range of 1.542 to 1.572. The optical properties of the resulting products are therefore comparable or better than those of lead crystal products, which is particularly beneficial for the grinded and engraved products.

The mean coefficient of longitudinal thermal expansion of the glass, and in the range of 20 to 300 ° C, is in all cases lower than that of the previously used crystal glasses in a general sense, which is favorable for the resistance of the glass to thermal shock.

The abrasion in lead crystal according to the chosen method is 0.266 pm.min ^-1 and in exemplary embodiments no. 1 to 5 is higher, which has a favorable effect on the processing speeds of these glasses by grinding and engraving.

In addition to antimony, other known diluents added to the batch, such as sulphates, chlorides and combinations thereof, can be used for the purification of the above-mentioned types of enamel, for example according to the author's certificate of the ČSSR no. 267821 etc ..

Commonly used colorants added to the batch, such as nickel oxide, cobalt, selenium compounds, rare earth oxides, manganese compounds, and combinations thereof, can be used to decolourize these enamels.

Industrial usability

The lead-free crystal glass according to the invention, containing ZrO ₂ , is intended for the manual and machine production of utility glass with a higher refractive index, particularly suitable for grinding, engraving and other decoration techniques for luxury products. This glass is hygienically harmless with respect to the content of pollutants in the leachate and its brilliance is equal to the lead crystal product.

This is the production of glass objects used in households and hospitality, for example. cups, castings, decanters, bowls as well as containers of various shapes and sizes used for decoration, e.g. vases, bowls, etc ..

Claims (2)

PATENT CLAIMS 1. Unleaded crystal glass suitable, in particular, for the hand and machine production of utility glass having a refractive index of 1.53 to 1.58, containing SiO ₂ , Al ₂ O ₃ , ZrO ₂ , CaO and / or magnesium oxide MgO, potassium oxide K ₂ O and / or sodium oxide Na ₂ O, characterized in that it contains 50 to 65 wt. of silica SiO _2, 0.1 to 10% by weight. % Al ₂ O ₃ , 0.5 to 17 wt. % ZrO ₂ , 10 to 22 wt. % potassium oxide K ₂ O and / or sodium Na ₂ O, 2 to 10 wt. calcium oxide CaO and / or magnesium MgO, wherein the Fe ₂ O ₃ content is in the range of 0.01 to 0.025% by weight, individually or in combination of 0.1 to 10% by weight. % barium oxide BaO, zinc oxide ZnO, boron oxide B ₂ O ₃ and lithium oxide Li ₂ O and traces up to 1 wt. antimony trioxide Sb ₂ O ₃ . 2. Lead-free crystal glass according to claim 1, characterized in that it contains, individually or in combination, traces of up to 1% by weight. titanium dioxide TiO ₂ and tin oxide SnO ₂ .