US007638450B2
(12) Ulllted States Patent (10) Patent N0.: US 7,638,450 B2 Ritter et a]. (45) Date of Patent: Dec. 29, 2009
(54) LEAD AND ARSENIC FREE OPTICAL 2003/0100433 A1 5/2003 Hayashi et a1. LANTHANUM BORATE GLASS 2003/0191008 A1 10/2003 Uehara 2003/0211929 A1 11/2003 Hayashi et a1. (75) Inventors: Simone Monika Ritter, MainZ (DE); * goiff et 31' 359/642 UteStefanie Woeli'el’ Hansen MainZ_Laubenheim Gensingen (DB5 ) 2006/0079389 A1 4/2006 HayashiI1 0 ...... FOREIGN PATENT DOCUMENTS (73) Assignee: Schott AG, MainZ (DE) DE 2 257 635 6/1973 ( * ) Notice: Subject to any disclaimer, the term of this DE 31 02 690 8/1982 patent is extended or adjusted under 35 DE 35 34 575 4/1986 U.S.C. 154(1)) by 0 days. DE 36 05 668 8/1986 (21) App1.No.: 11/412,673 (Commued) OTHER PUBLICATIONS (22) Filed: Apr. 27, 2006 JP Pub. No. 2003-238198, Nakayama Kazutoshi, Aug. 27, 2003. (65) Prior Publication Data US. Cl- ...... is useful in mapping’ projection’ telecommunication, 501/77; 501/49; 501/ 50 optical communication engineering, and mobile drive and (58) Field of Classi?cation Search ...... 501/78, laser technology, has a refractive index of 1 .75§nd§1.83, an 501/79 Abbe number of 34§Vd§44, and Tg§560° C. The glass is See application ?le for complete search history. free of WO3 and TeOZand has a composition in percent by _ Weight based on oxide content of: SiO2, 0.5-8; B2O3, 10-25; (56) References C‘ted ZnO, 10-22; La2O3, 23-34; Ta2O5, >15-25; Nb2o,, 0.5-15; U_S_ PATENT DOCUMENTS A1203, 0-2; and can include optional ingredients, e.g. alkali and/or alkaline-earth oxides. In addition, a sum of B203 and Q2 * lsla‘iam Sol/78 ZnO is 33 to 41% by Weight and preferably a sum of La2O3+ 6,818,578, , B2 11/2004 Tachiwamae ara ...... Ta2OS+Nb2OS+YZO3+ZVO21s- greater than 50% by We1ght.- 7,091,145 B2 8/2006 Wolff et a1. 2002/0006857 A1 l/2002 Tachiwama 10 Claims, 2 Drawing Sheets .- 1991-34-01.: . "fit-bbEi'oa’f ,. . _ » ’ ‘12001300 "1100' 5'00 "e00" 700 ‘10001-900 10001100 1200 1300140015001600 Temperature in [°C] US 7,638,450 B2 Page 2 FOREIGN PATENT DOCUMENTS JP 62-100449 5/1987 JP 2002173336 6/2002 DE 101 26 554 V2002 JP 2003201142 7/2003 EP 1 236 694 9/2002 JP 2003238198 8/2003 FR 2 841 237 12/2003 JP 2003300751 10/2003 JP 56-5345 1/1981 JP 60221338 11/1985 * cited by examiner US. Patent Dec. 29, 2009 Sheet 1 of2 US 7,638,450 B2 Fig. 1 Temperature in [°C] US. Patent Dec. 29, 2009 Sheet 2 of2 US 7,638,450 B2 Fig. 2 I HI] . ‘I. v T rr'f'soo' ‘i- ‘.550 ' 600 650 .7700 Wave length [nm] US 7,638,450 B2 1 2 LEAD AND ARSENIC FREE OPTICAL laborious post-processing, cooling and/ or cold re-processing LANTHANUM BORATE GLASS must not be necessary. Because of the required high accuracy of geometries, precision instruments With high grade and CROSS-REFERENCE therefore expensive mold materials have to be used for such a pressing procedure. The lifetimes of such molds massively The invention described and claimed herein below is also affect the pro?tability of the products and/or materials pro described in German Patent Application 10 2005 020 423.6 duced. A very important factor for a long lifetime of the molds ?led on Apr. 29, 2005 in Germany. A claim of priority of is a Working temperature Which is as loW as possible, but invention for the invention disclaose herein beloW under 35 Which can only be loWered to a point at Which the viscosity of U.S.C. 119 is based on the aforesaid German Patent Applica the materials to be pressed is yet su?icient for the pressing tion. procedure. This means, that there is a direct relationship betWeen the processing temperature and thereWith the trans BACKGROUND OF THE INVENTION formation temperature Tg of a glass to be processed and the pro?tability of such a pressing process: The loWer the trans 1. The Field of the Invention formation temperature of the glass, the longer the lifetimes of The present invention relates to a lead and arsenic free and the molds; and therefore the higher the earnings. Thus, there preferably gadolinium free and ?uorine free optical lantha is a demand for so-called “loW-Tg-glasses”, i.e. glasses hav num borate glass, to the use of such a glass in the ?elds of ing loW melting points and transformation temperatures, i.e. mapping, projection, telecommunication, optical communi glasses With a viscosity at temperatures Which are as loW as cation engineering, mobile drive and laser technology, as Well 20 possible Which is suf?cient for processing. as to optical elements respectively preforms of such optical Further, from a process technical point of vieW of the melt elements. there is a groWing demand for “short” glasses, i.e. glasses 2. Description of Related Art having a viscosity Which varies strongly Within a certain In the recent years, the tendency on the market in the ?eld viscosity range at a relatively small change in temperature. of optical technologies as Well as opto-electronic technolo 25 This behaviour has the advantage in the melting process that gies (application ?elds mapping, projection, telecommunica the times of hot forming, i.e. the closure times of the molds, tion, optical communication engineering, mobile drive and can be decreased. Because of that, on the one hand the laser technology) goes more and more into the direction of throughput Will be increased, i.e. the cycle times Will be miniaturization. This can be seen With the ?nished products reduced. On the other hand, because of that also the mold Which become smaller and smaller and naturally requires an 30 material Will be protected Which also has a positive effect on increasing miniaturization of the single structural members the total production costs, as described above. Such “short” and components of such ?nished products. For the producers glasses have the further advantage that also glasses With of optical glasses, this development means a clear decrease of higher tendency to crystallization may be processed by the the demanded volumes of rough glass in spite of increasing faster cooling than With corresponding longer glasses. There quantities of ?nished products. At the same time, there is an 35 With prenucleation Which could cause problems in succeed increasing pricing pressure from the side of the reprocessors ing steps of secondary hot forming Will be avoided. This to the producers of glass, since With the production of such presents the possibility that such glasses may also be smaller components made of block and/ or ingot glass notice stretched to ?bres. ably more Waste Will be produced proportionally based on the Furthermore it is also desirable that, besides the mentioned product and for the processing of such miniature parts a 40 and the required optical properties, the glasses are suf?ciently higher operating expense is necessary than for larger struc chemically resistant. tural members. The prior art already describes glasses With similar optical Instead of the removing of glass portions for optical com state or With a comparable chemical composition, but these ponents from block or ingot glass Which is common till today, glasses have immense disadvantages. In particular, many of therefore recently production procedures become important 45 the glasses contain higher proportions of Gd2O3 Which as a in Which directly after the glass melt preforms respectively rare-earth oxide has a Weak band at 590 nm and thus deterio pills Which are as close as possible to the ?nal contour respec rates the internal transmittance, and/or components Which tively geometry such as eg gobs or spheres may be yielded. increase the tendency to crystallization, such as eg TiO2. For example, the reprocessors’ requests for preforms Which US 2003/0211929 relates to an optical glass for precisely are close to the ?nal geometry for re-pressing, so-called “pre 50 pressed products having a Tg of loWer than 6300 C. The latter cision gobs”, are increasing. Normally, these “precision property is achieved by the addition of a very high amount of gobs” preferably mean completely ?re-polished, free or half B203 and ZnO. In every case, the glass contains Gd2O3 in a free formed glass portions Which are already portioned and proportion of at least 5% by mol. have a geometry Which is close to the ?nal form of the optical JP 2003/201142 describes an optical glass for precisely component. 55 pressed products having also a loW Tg. Here also this property Such “precision gobs” may preferably also be converted is achieved by the addition of a very high amount of B203 and into optical elements such as lenses, aspheres etc. by the ZnO. In every case, the glass contains Gd2O3 in a proportion so-called “precise pressing” or “precise molding” process. of at least 6% by Weight. Then, a further processing of the geometric form or the sur US 2003/0191008 comprises an optical glass With a high face with eg a surface polish is no longer required. This 60 refractive index for the precise pressing technology. The glass procedure can comply With the smaller volumes of melted contains very high proportions of Nb2O3 of at least 30% by glass (distributed on a high number of small parts of material) Weight. Nb 205 in such high proportions deteriorates the inter in a ?exible Way by shorter set-up times. Because of the nal transmittance of the glass. relatively loWer number of parts per time unit and the nor JP 2003/238198 describes an optical glass for precisely mally smaller geometries, the creation of value cannot be 65 pressed products having a loW Tg. The latter property is caused by the value of the material alone. Rather, the products achieved by the addition of LiF and/or ZnF, Wherein in every have to leave the press in a state ready for installation, i.e. case ?uorine is contained as a component in an amount of at US 7,638,450 B2 3 4 least 9% by Weight. Fluorine is disadvantageous With respect to a stable melting and production process, in particular -continued because of the strong evaporation. JP 2003/300751 describes a loW melting glass for precisely Na2O 0-6 K20 0-8 pressed products. The loW Tg of480 to 580° C. is i.a. achieved Cs2O 0-9 by the addition of Bi2O3. In every case, Bi2O3 is contained MgO 0-5 and imparts self-color to the glass Which deteriorates the CaO O-5 SrO O-5 internal transmittance of the glass. BaO O-5 JP 2002/ 173336 describes a loW melting phosphate glass v203 0-10 having a high dispersion respectively loW Abbe number of 20 Tio2 0-6 to 32. Zro2 0-11 DE 35 34 575 relates to a glass for eye glass lenses Which Hfo2 0-6 2 B203 + ZnO 30-45 in every case comprises a component for coloration. Here, E Alkali metal oxides O- 10 lanthanum oxide is only an optional component. E Alkaline-earth metal oxides O-8 DE 36 05 668 relates to an optical tellurite glass Which in 2 A1203, Y2O3, W03, TiO2, ZrO2, 0-15 HfO2, Alkaline-earth metal oxides every case comprises toxic tellurium oxide as a component. Conventional re?ning agents O-2 DE 101 26 554 describes borosilicate glasses With very high refractive indexes. The documents EP 1 236 694 A1, US 2003/0100433 and Preferably the sum of the oxides La2O3+Ta2O5+Nb2O5+ US 2003/0211929 describe optical glasses Which are lead and 20 Y2O3+ZrO2 is higher than or equal to 50% by Weight based on ?uorine free, but Which in every case contain Gd2O3. oxide content. JP 60-221338 relates to glasses Which in every case contain Preferably the glasses are free of components Which are not lithium oxide as a component and in Which at least a part of mentioned, one oxide is replaced by ?uorine. The glasses according to the present invention have the 25 same optical state, such as the Abbe number and the refractive SUMMARY OF THE INVENTION index, as knoWn optical glasses of similar glass families. HoWever they are featured by good meltability and process The object of the present invention is, to provide an optical ability, loW production costs due to reduced processing costs, glass With Which desired and advantageous optical properties as Well as a good environmental compatibility. (nd/v d) With concurrent loW transformation temperatures can 30 In particular, these glasses are suitable for processing close be realiZed, in particular also by virtue of ecological consid to the ?nal contour, such as eg the production of precision erations Without the use of PbO and As2O3 and preferably gobs, as Well as for a blank pressing process (precise press also Without the components Gd2O3 and ?uorine. This ing) for producing an optical component With accurate ?nal glasses should further be processible by precise pressing and contour. In this context, preferably the viscosity-temperature should be suited for the application ?elds mapping, projec 35 pro?le and the processing temperature of the glasses accord tion, telecommunication, optical communication engineer ing to the present invention Were adjusted, so that such a hot ing, mobile drive and laser technology, should have a refrac forming close to the ?nal geometry respectively contour is tive index nd of 1.75 The properties of the glass thus obtained are given in table Sb2O3 0-1 and/or SnO 0-1 and/or 3 as example 10. S04 ’ 0-1 and/or F’ 0-1 Example 2 60 Also ?uorine and ?uorine-containing compounds tend to Tables 2 to 5 comprise the examples 1 to 26 according to evaporation during the melting and melting-on process and the present invention. thus make an accurate adjustment of the glass composition All glasses according to the present invention have a Tg of dif?cult. Therefore, the glass according to the present inven loWer than or equal to 5600 C., have a very good alkali tion preferably is also free of ?uorine. 65 resistance and can be processed Well. The color code of the Further, the present invention relates to the use of the glasses according to the present invention achieves a value of glasses according to the present invention in the application up to 38/32. US 7,638,450 B2 13 14 TABLE 5-continued Examples 21 to 26 data based on oxide in % by Weight! Exp. 21 22 23 24 25 26 Cs2O 2.24 Nb2O5 4.11 3.93 8.23 4.22 2.05 4.22 La2O3 27.95 24.12 22.02 28.60 29.29 28.64 Ta2O5 15.67 21.84 23.67 16.04 16.43 16.06 Y2O3 2.45 2.51 0.64 2.51 Hfo2 0.54 MgO 1.12 CaO 0.55 0.57 SrO 1.78 BaO ZnO 18.76 17.94 15.07 19.24 19.71 19.28 ZrO2 2.93 2.80 2.38 3.00 3.08 1.47 Tio2 1.00 Sb2O3 0.20 0.20 0.20 0.20 0.20 0.20 2 100.0 100.0 100.0 100.0 100.0 100.0 La2O3 +Zro2 +Nb2O5 + 53.1 53.2 56.3 54.4 51.5 52.9 Ta2O5 +Y2O3 + HfO2 2 R20 (Alkalies) 3.8 5.5 4.1 1.9 1.9 2.7 2 RO (Alkaline-earths) 0.0 0.0 1.1 0.5 2.3 0.0 21 B203, ZnO 38.3 36.6 36.3 39.3 40.2 39.4 2A12O3,Y2O3, 10.2 9.8 6.5 7.4 5.6 7.8 W03, T102, ZrO, HfO2, R20 Properties TZ-(IOMAOO m) 0.96 0.64 0.88 0.95 T,- (10 mm, 500,550 m) 0.992 0.729 0.922 0.99 Color code 38/31 44/34 37/31 39/33 11d (71Qh) 1.78203 1.76629 1.81504 1.80842 1.79501 1.80156 vd (71Qh) 40.61 39.10 37.06 40.97 42.36 39.97 Pgf 0.5674 0.5704 0.5751 0.5669 0.5642 0.5698 APgf —0.0081 —0.0077 —0.0064 —0.0080 —0.0083 —0.0068 6620.300. C_)[1076/1<] 7.68 7.43 6.95 7.4 7.6 7.45 Tg [0 C.] 545 548 522 526 531 524 p [g/crn3] 4.4613 4.3805 4.5341 4.5773 4.5590 4.5170 AT = (T(l6gn = 107-“) - 93 94 98 “10561110130 [K] SR [class] (180 8424) AR [class] (ISO 10629) The invention claimed is: 1. A lead-free, ?uorine-free and arsenic-free optical glass ‘Continued having a refractive index n‘1f of 1.75§nd§1.83 and an Abbe 45 2 Alkalinwmh mml oxid?s 0_8 number vdof34§vd§ 44, sa1d glass compr1s1ng,1npercentby 2 1412033203, Tl02, Z102, 0-15 Weight based on oxide content: Hfog, Alkalin?-ealth Inml oXid?s at least one re?ning agents 0-2; $02 058 50 Wherein said glass is free of WO3, said glass is free of TeO2, B203 10-25 said glass is free of lead, said glass is free of ?uorine, and in?) 162-???‘ said glass is free of arsenic; and a _ T915053 >1 5.2 5 having a transformation temperature Tg that is at most 5 600 Nb2O5 0-5'15 C. and a viscosity that decreases from 107'6 to 1013 dPas 31283 8'? 55 When a temperature decrease of at most 1000 K. occurs. 2 _ NaZO 0—6 2. The optical glass as de?ned in claim 1, containing from 52% 8'2 0.1 to 4 percent by Weight of said LiZO, from 1.65 to 10 M50S 0_5' percent by We1ght. of sa1d. ZAlkah. ox1des,. and from 0 to CaO 0-5 60 1percent by Weight of said at least one re?ning agent. 1831;?) 8:; 3. The optical glass as de?ned in claim 1, Wherein a sum of Y2O3 04o La2O3 +Ta2O5 +Nb2O5+Y2O3 +ZrO2 is greater than 50 per TlO2 0-6 cent by Weight. 3% 8:? 4. A lead-free, ?uorine-free and arsenic-free optical glass 2 B2203, 2110 3341 65 having a refractive index ndof 1.75 éndl .83 and an Abbe 2 Alkali metal oxides 1.65-10 number vd of 34évd44, said glass comprising, in percent by Weight based on oxide content: US 7,638,450 B2 15 16 -continued SiO2 1-7 Li2O 0.5-4 B203 15-24 Na2O 0-4 Z110 16.2-22 5 K20 0-4 La2O3 23-33 CSZO O-4 Ta2O5 15.5-23 MgO O-4 Nb2O5 1-8 CaO O-4 Al2O3 O-1.5 SrO O-4 Li2O 0.1-4 BaO O-4 Na2O O-5 1O Y2O3 O-9 K20 O-6 TiO2 O-3 C820 O-8 ZrO2 1-10 MgO O-4 HfO2 O-3 CaO O-4 21 B203, ZnO 38-41 SrO 0-4 2 Alkali metal oxides 1.65-6 BaO 0-4 15 E Alkaline-earth metal oxides 0-4 Y2O3 0-9 2 A1203, Y2O3, T102, Z102, 0-13 TiO2 O-3 HfO2, Alkaline-earth metal oxides ZrO2 1-10 at least one re?ning agents 0-2; 11102 0-3 2 B203, ZnO 34-41 2 Alkali metal oxides 1.65-7 20 and containing more than 50 percent by Weight of a sum of E Alkaline-earth metal oxides O-5 La2O3 +Ta2O5 +Nb2O5 +Y2O3 +ZI-O2; 2 A1203, Y2O3, T102, ZrO2, 0-13 HfO2, Alkaline-earth metal oxides wherein said glass is free of ?uorine, said glass is free of at least one re?ning agents 0-2; TeO2, said glass is free of W03, said glass is free of lead, and said glass is free of arsenic; and d . . h 5 0 b _ f f 25 having a transformation temperature Tg that is at most 5 60° an Comalmng more t an percent y Welght O a sum 0 C. and a Viscosity that decreases from 107'6 to 1013 dPas La203 ‘P17212057’ 2O.5+Y2O3 +Zr02; . _ When a temperature decrease of at most 100° K. occurs. Wher.em saldglass Is free OfWO3’ Saul glass 15 free o_fTeO2’ 6. The optical glass as de?ned in claim 1, containing up to sa1d glass 1s free of lead, sa1d glass 1s free of ?uonne, and one percent by W ei ght of Said at least one re?ning agent’ and said lass is free of arsenic; and - - - - havin g transformation tern eratureT thatis at most 560° 30 Wherem Sa1~d -at least one re?mng age? 15 Selected from the g p g group cons1st1ng of Sb2O3, SnO, SO4 ' and F. C' and a vlscoslty' ' that decreases from 10 7.6 to 10 13 dPas 7. The optical glass as de?ned in claim 1, Which is free of When a temperature decrease of at most 100° K. occurs. gadolinium 5'. A lead-free‘, ?uorine-free and arsen1c-free opt1cal glass 8' An 0 pti C a1 e1 em em Comprising an Optical glass accord_ havmg a refracnve Index n‘?Of 175219;} ‘.83 and an Abbe 35 ing to any one of claims 1 to 7, said optical element consisting number Vd “MEX/“Y; 44’ sa1d glass Compnsmg’ lnpercem by of a lens, asphere, a prism, or a compact structural member for Welght based on oxlde Content: use in the ?eld of mapping, projection, telecommunication, optical communication engineering, mobile drive, or laser technology. $102 1.7 40 ~ 9. An optical element comprising an optical glass accord B203 15-23 mg to any one of cla1ms 1 to 7. ZHO 16-2'22 1 0. A method of making an optical element, comprising the 5:283 1 step of precise pressing an optical glass according to any one Nb22O55 ‘1.8 ofclaims 1 to 7. A1203 0-1.5