# US 4,400,473 A · Acidproof, hydrolysis-resistant optical and ophathalmic glass of low density

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- Number: US 4,400,473 A
- Document ID: US4400473A
- Status: Granted
- Kind: A
- Application number: 06/384,462
- Filed: 1982-06-02
- Granted: 1983-08-23
- Earliest claimed: 1980-07-14
- Assignees: Schott Glaswerke
- Inventors: Karl Mennemann; Georg Gliemeroth; Volkmar Geiler
- Web page: https://patentgrep.com/patent/US4400473A

## CPC

- C03C 3/074: containing zinc
- C03C 3/064: containing boron
- C03C 3/066: containing zinc
- C03C 3/068: containing rare earths
- C03C 3/072: containing boron
- Y10S 501/901: having R.I. at least 1.8
- Y10S 501/903: having refractive index less than 1.8 and ABBE number less than 70
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

An improved optical glass having an index of refraction of .gtoreq.1.69, an Abbe number of .gtoreq.38, and a density of .ltoreq.3.25 g/cm.sup.3, represents a further development of another optical glass recently provided by the same inventors. The new glass has improved suitability for continuous-tank manufacture and increased acidproofness and differs from the other glass in its content of 0.5-4.0% by weight of P.sub.2 O.sub.5 ; its sum total of SiO.sub.2 +B.sub.2 O.sub.3 +Al.sub.2 O.sub.3 +P.sub.2 O.sub.5 being 38.5-41.5% by weight; and its sum total of MgO+CaO being 13-17.5% by weight. The full glass composition, e.g. is in % by weight: ______________________________________ SiO.sub.2 26.0-32.5 B.sub.2 O.sub.3 6.0-12.0 Al.sub.2 O.sub.3 0-3.0 P.sub.2 O.sub.5 0.5-4.0 SiO.sub.2 + B.sub.2 O.sub.3 + Al.sub.2 O.sub.3 + P.sub.2 O.sub.5 = 38.5-41.5 Li.sub.2 O 0-5 Na.sub.2 O 0-6 K.sub.2 O 0-8 Li.sub.2 O + Na.sub.2 O + K.sub.2 O = 4.5-12.0 MgO 0-8 CaO 9-16 MgO + CaO = 13-17.5 SrO 0-6 BaO 0-5 ZnO 0-7 PbO 0-4 SrO + BaO + ZnO + PbO = 0-7 MgO + CaO + SrO + BaO + ZnO + PbO = 17-24 La.sub.2 O.sub.3 6-11 ZrO.sub.2 5-8 La.sub.2 O.sub.3 + ZrO.sub.2 = 13.5-17.5 TiO.sub.2 5-9 Nb.sub.2 O.sub.5 6-11 WO.sub.3 0-4 TiO.sub.2 + Nb.sub.2 O.sub.5 + WO.sub.3 = 14-18 La.sub.2 O.sub.3 + ZrO.sub.2 + TiO.sub.2 + Nb.sub.2 O.sub.5 + WO.sub.3 = 28-33 ZrO.sub.2 + TiO.sub.2 + Nb.sub.2 O.sub.5 = 20-26 ______________________________________

## Claims

### Claim 1

An optical and ophthalmic glass having n.sub.d 22 1.69, v.sub.d.gtoreq. 38, a density .gtoreq.3.25 g/cm.sup.3, an expansion coefficient .alpha..sub.20.degree.-300.degree. C. of (80-97).multidot.10.sup.-7, a high acid and hydrolysis resistance and sufficient stability for continuous-tank manufacture,
consisting essentially of, in wt. %,

### Claim 2 (depends on 1)

A glass of claim 1, of the composition in % by weight.
______________________________________ SiO.sub.2 29-32 B.sub.2 O.sub.3 7.5-10 P.sub.2 O.sub.5 0.5-2.5 Al.sub.2 O.sub.3 0-3 SiO.sub.2 + B.sub.2 O.sub.3 + Al.sub.2 O.sub.3 + P.sub.2 O.sub.5 = 38.5-41.5 Li.sub.2 O 0.5-4 Na.sub.2 O 1.5-3.5 K.sub.2 O 2.5-7 Li.sub.2 O + Na.sub.2 O + K.sub.2 O = 6-10 MgO 1.0-5.0 CaO 10.0-13.5 MgO + CaO = 13-17 SrO 0-5 ZnO 0-7 BaO 0-5 PbO 0-4 SrO + ZnO + BaO + PbO = 0-7 MgO + CaO + SrO + ZnO + BaO + PbO = 16-22 La.sub.2 O.sub.3 6-11 ZrO.sub.2 5-8 La.sub.2 O.sub.3 + ZrO.sub.2 13.5-17.5 TiO.sub.2 5-9 Nb.sub.2 O.sub.5 6-11 TiO.sub.2 + Nb.sub.2 O.sub.5 = 15-17 La.sub.2 O.sub.3 + ZrO.sub.2 + TiO.sub.2 + Nb.sub.2 O.sub.5 = 28-33 ZrO.sub.2 + TiO.sub.2 + Nb.sub.2 O.sub.5 21-25 ______________________________________

### Claim 3 (depends on 1)

A glass of claim 1, of the composition in % by weight,
______________________________________ SiO.sub.2 30.5-31.5 B.sub.2 O.sub.3 8.0-9.0 Li.sub.2 O 1.0-2.0 Na.sub.2 O 2.0-4.0 K.sub.2 O 3.0-5.0 MgO 2.0-4.0 CaO 11.0-13.0 La.sub.2 O.sub.3 8.5-9.5 ZrO.sub.2 6.5-8.0 TiO.sub.2 7.0-9.0 Nb.sub.2 O.sub.5 7.0-9.0 SrO 2.0-4.0 P.sub.2 O.sub.5 1.0-2.0 ______________________________________

### Claim 4 (depends on 1)

A glass of claim 1, of the composition in % by weight,
______________________________________ SiO.sub.2 29.0-30.5 B.sub.2 O.sub.3 8.0-10.0 Li.sub.2 O 2.0-4.0 Na.sub.2 O 2.0-4.0 K.sub.2 O 3.0-5.0 MgO 3.0-5.0 CaO 10.0-12.0 La.sub.2 O.sub.3 7.0-8.5 ZrO.sub.2 7.0-8.0 TiO.sub.2 6.0-8.0 Nb.sub.2 O.sub.5 9.0-11.0 P.sub.2 O.sub.5 1.0-2.0 ZnO 3.0-5.0 ______________________________________

### Claim 5 (depends on 1, 2)

A lens made of the glass of claim 1 or 2.

### Claim 6 (depends on 5)

A lens of claim 5 wherein the lens is an eyeglass lens.