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Home , Potassium oxide

United States Patent 19 11 3,904.425 Young et al. (45) Sept. 9, 1975

54) ABSORPTIVE GLASS Primary Examiner-Harvey E. Behrend 75 Inventors: Robert W. Young, Woodstock, Attorney, Agent, or Firm-William C. Nealon; H. R. Conn.; Robert E. Graf, Southbridge, Berkenstock, Jr. Mass. W EXEMPLARY CLAIM 73) Assignee: American Optical Corporation, 1. A glass material having a calculated composi Southbridge, Mass. tion comprising 22 Filed: June 12, 1964 21 Appl. No.: 374,811 Percent by Weight Dioxidc (SiO) 5.9 Oxide (NaO) 6.5 (52) U.S. Cl...... 106/52; 106/50 Oxide (KO) 6.8 (51 l Int. Cl...... CO3C 13/00 Oxide (CaO) 6.5 58) Field of Search...... 106/50, 52 Trioxide (SbO) 0.4 Aluminum Oxide (AO) 4. Oxide (ZnO) 2.2 56) References Cited Dioxidc (TiO) 0.4 Dioxide (MnO) 23.4 UNITED STATES PATENTS Oxide (CrO) O.S 2,676,09 4/1954 Barnes ct al...... 106752 Tct O).() 2,776,900 l/1957 Duncan et al...... 106/52 2,898,219 8/1959 Duncan ct al...... 106/52 2,902,377 9, 1959 Duncan...... 106/52 a 100 micron thickness of said glass material having 3,146,2O 8/1964 Upton et al...... 106/52 an optical greater than 0.25 at least for light 3,20386 8/1965 Bull et al...... 1 O6/52 from 0.4 to 0.6 microns wavelength. FOREIGN PATENTS OR APPLICATIONS 6 4,357 21 1961 Canada...... 106/52 6 Claims, No Drawings 3,904,425 2 ABSORPTIVE GLASS als should have optical at least as high as 0.25 The field of this invention is that of glass composi in sample thickness as small as 100 microns at least for tions and the invention relates more particularly to light of wavelengths between 0.4 and 0.6 microns. Ex novel and improved absorptive glass materials. pressed another way, this means that thicknesses of In an important application of fiber optics, a great these glass materials as small as four thousandths number of very small optical fibers each having a light (.004) of an inch should be adapted to provide for at conducting glass core and a light-insulating glass clad least 75% absorption of the light from 0.4 to 0.6 mi ding are fused together in side-by-side parallel relation crons wavelength incident thereon. to each other to form a vacuum-tight faceplate for a The absorptive glass material provided by this inven cathode-ray tube. In such devices, very fine filaments tion embodies (SiO2) as its major ingre of light-absorbing glass material are fused between the dient and also embodies (NaO) and/or optical fibers at spaced locations throughout the face potassium oxide (KO) as fluxes to aid in glass forma plate and the inner surface of the faceplate is coated tion. The glass material further embodies with photo-emissive phosphors or the like. In this ar (CaO) as a glass stabilizer and rangement, the cathode-ray tube can form a light image 15 (SbO) to facilitate fining of the glass material. Prefer on the inner surface of the faceplate in conventional ably the glass also contains aluminum oxide (AlO3) to manner and the optical fibers can each conduct light promote durability of the glass. The glass material can from a specific part of the image to reproduce the also contain (ZnO) to further stabilize the image with high resolution on the outer surface of the glass and can contain titanium oxide (TiO) to help reg faceplate. The light-absorbing filaments absorb un ulate viscosity of the glass. wanted, stray light which is emitted by the tube phos phors but which is not conducted through specific opti In accordance with this invention, the glass material cal fibers, thereby to assure that the stray light is not must contain one or more colorants selected from the transmitted through the faceplate and does not wash group consisting of (MnO), nick out contrast between light and dark portions of the 25 elic oxide (NiO), chromium oxide (CrO), ferric light image reproduced on the outer surface of the oxide (FeO), oxide (CoO) and cupric oxide tube. - (CuO), the quantity of the selected colorant or color It is an object of this invention to provide a glass ma ants embodied in the glass being sufficient to provide terial having very high absorptive properties for use in the glass with an optical density of 0.25 even for very forming light-absorbing filaments to be incorporated in 30 thin sheets or filaments of the glass as small as 100 mi fiber optical devices. It is therefore an important object crons thickness - at least for light from 0.4 to 0.6 mi of this invention to provide such an absorptive glass crons wavelength. Where manganese dioxide com material which can be conveniently and economically prises the sole colorant embodied in the glass, the man drawn into the form of very fine filaments of substan ganese dioxide must comprise at least about 20 percent tially uniform diameter and absorptive properties. Fur 3 5 by weight of the glass material in order to achieve the ther objects of this invention are to provide such ab minimum degree of optical density which is required. sorptive glass materials which can be conveniently However additional manganese dioxide or other color fused together with glass materials customarily embod ants can also be added for achieving greater optical ied in optical fibers; to provide such glass materials densities without adversely affecting working proper which are stable under the temperatures to which cath ties of the glass material. On the other hand, where the ode-ray tubes are subjected; and to provide such glass manganese dioxide content of the glass material com materials which are chemically unreactive with respect prises less than 20 percent by weight of the glass mate to phosphors and the like with which cathode-ray tube rial, the manganese dioxide must be supplemented by faceplates are frequently coated and which are particu other colorants in order to provide the desired optical larly adapted for absorption of light of the wavelengths density. For example, where the manganese dioxide emitted by such phosphors. It is a specific object of this content of the glass is 12 percent by weight of the glass invention to provide such absorptive glass materials material, the manganese dioxide can be supplemented which have an optical density of 0.25 or more for thick by at least 8 percent by weight of nickelic oxide alone. ness on the order of 100 microns at least for light of Similarly, where the manganese dioxide content of the wavelengths between 0.4 and 0.6 microns. Other ob 50 glass material is omitted, the manganese dioxide can be jects of this invention appear in the following detailed replaced by at least 5 percent by weight of nickelic description of preferred embodiments of this invention. oxide and at least 3.5 percent by weight of cobalt oxide. It will be understood that optical fibers employed in The various ingredients of the glass material of this in thin cathode-ray tube faceplates are ordinarily on the vention can of course be varied within certain limits so order of 25–50 microns in diameter and that the light 55 that the calculated oxide composition of this glass ma absorbing filaments fused within the fiber faceplates terial can be set forth as follows: must also be quite small in diameter and must be well dispersed throughout the faceplate if they are to be ac Percent by Weight commodated in the faceplates without adversely affect 60 ing light images transferred through the faceplate. This Silicon Dioxide (SiO,) 4() to 65 means that the absorptive properties of the glass mate Sodium Oxide (NaO) () to () Potassium Oxide (KO) () toy l() rials of this invention must be very high with respect to Calcium Oxide (CaO) 4 to 9 light of the particular wavelengths emitted by phos Antimony Trioxide (SbO) ().3 to () phors usually employed on such faceplates if the fila Aluminum Oxide (AO) () to 2 65 Zinc oxide (ZnO) () to 3 ments are to be effective in absorbing stray light emit (TiO) () to 2 ted by the phosphors before it escapes from the face TTH------plates. In fact it has been found that such glass materi 3,904,425 3 4. wherein the combined content of NaO and KO equals EXAMPLE I at least 1 () percent by weight, said glass material including at least one colorant se Percent by Weight lected from the group consisting of Silicon Dic)xicle (SiO.) 5.9 5 Sociium Coxicie (NaO) 6.5 Potassium Oxide (KO) 6.8 Percent by Weight Calcium Oxide (CaO) 6.5 Antimony Trioxide (SbO) ().4 Manganese Dioxide (MnO, ) () to 32 Aluminum Oxide (AO) 1.4 Nickulic Oxide (NiO.) () to 9 Zinc Oxicic (ZnO) 2.2 Titanium Dioxide (TiO) ().4 Chromium Oxide (C.O.) () to ().5 () Ferric Oxide (FeO.) () to 9 Manganesc Dioxide (MnO) 23.4 Cobalt (xide (CoO) () to 6 Chromium Oxide (CrO) ().5 Cupric Oxide (CuO) () t 9 Total O().() wherein a content of MnO, less than 20 percent by 5' said glass having an optical density greater than 0.25 in weight is supplemented by others of said colorants for a sample sheet of glass of 100 microns thickness at least achieving an optical density of at least 0.25 in thick for light from 0.4 to O.6 microns wavelength. nesses of 100 microns at least for light of wavelengths Other examples illustrating calculated oxide compo between ().4 and 0.6 microns. sitions of absorptive glass materials provided by this in vention are as follows: Although various conventional ingredients can be 20 employed for forming a glass material having calcu EXAMPLE 2 lated oxide compositions as set forth above, a preferred raw batch composition for achieving the glass material of this invention could comprise the following: Percent by Weight 2 5 Silicon Dioxide (SiO, ) 5 Sodium Oxide (NaO) Potassiurn Oxide (KO) Calciun Oxide (CaO) EXAMPLE I (BATCH) Antimony Trioxide (SbO) Aluminum Oxide (AO) Zinc Oxide (ZnO) Parts by Weight Titanium Dioxide (TiO) Manganese Dioxide (Mn(D) Silicon Dixide (SiO) 36.33 Total Sociu in C:rbonate (NCO) 778 Potissium Carhunate (KCC).) 8.33 Calciuin Carbonate (CaCO) 83 Altimony Trioxide (Sh.O.) 28 this glass material having an optical density greater Aluminum Hydroxide (Al(OH): ) 5() Zinc Oxide (ZnO) 54. than 0.25 in a thickness of 100 microns for light at least Iitanium Dioxide (iO.) 28 from 0.4 to 0.6 microns wavelength. Manganese Dioxide (MnO,) f38 Chromiuin C)xicle (CrO.) 35 EXAMPLE 3 Percent by Weight Silicon Dicyxide (SiO) 6.6 According to this invention, the described raw batch Socliun Oxide (NaO) 7.8 Post:ussium Oxicle (KO) 8.() ingredients are weighed out and mixed in a conven Calcium Oxide (CaO) 7.7 tional manner and are than placed in high-alumina clay Antimony Trioxide (SbO) 5 Aluminum Oxide (AO) 1.7 pot. A zircon-mullite pot, a dense fire clay pot, or other Zinc Oxide (ZnO) 2.6 conventional crucible means could also be employed. Titanium Dioxide (TiO) 5 The pot is then placed in an electrical furnace of the Nickelic Oxide (NiO) 6 silicon-carbide resistance type or other conventional Cobait Oxide (CoO) 3.6 furnace for melting the batch ingredients at a tempera Total ()().) ture of 2500–2700 F. As the glass batch melts, addi tional batch material is added to the pot until the de this glass material having an optical density greater sired batch size is achieved. In a conventional electrical than 0.25 in a thickness of 100 microns at least for light furnace, neutral or mildly oxidizing conditions will nor from 0.4 to 0.6 microns wavelength. mally be established. However it has been found that reducing conditions provided by the addition of car EXAMPLE 4 bon, aluminum or silicon powders to the batch ingredi ents can also be employed in making the glasses of this Percent by Weight invention. After melting of the batch ingredients has Silicon dioxicic (SiO) 46.38 Sudium Oxide (NaO) 5.85 been accomplished, the batch is maintained at a tem Potassium Oxide (KO) 6.05 perature of 2300°-2500 F for 1–3 hours during fining 60 Calcium Oxide (CaO) 5.78 Antimony Trioxide (SbO) 34 of the batch in conventional manner. The batch is then Aluminum Oxide (AlO) 1.29 cooled slowly with strirring and is cast at a temperature Zinc Oxide (2nd) 1.97 Titanium Dioxide (TiO) 34 of 2000-2200 F. The glass can then be annealed for Manganese Dioxide (MnO) 23.4 several hours at a temperature of 900-1 100 F. and Ferric Oxide (FeC)) 5. can be slowly cooled to room temperature over night. Cobalt Oxide (CoO) 3.5 The calculated oxide composition of glass prepared from such batch ingredients is as follows: this glass material having an optical density greater 3,904,425 S 6 than ().25 in a thickness of l ()() microns at least for light a 100 micron thickness of said glass material having an from ().4 to 0.6 microns wavelength. optical density greater than ().25 at least for light from Other examples of glass compositions provided by ().4 to ().6 microns wavelength. this invention, all of which provide optical densities greater than ().25 for light of the desired wavelengths, 5 2. A glass material having a calculated oxide compo are as follows: Stiof comprising

Percent by Weight Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. 5 6. 7 8 9 () 12 3. SiO, 52. 51.8 52 51.9 , 48.42 48.42 49.52 46.04 51.5 NaO 6.6 6.6 6.5 6.5 6.()6 6. ()6 6.2 5.76 6.5 KO 6.8 6.8 6.8 6.8 6.34 6.34 6.48 6.)3 6.7 CaO 6.5 6.5 6.5 6.5 6.)6 6.()6 (.2 5.76 6.4 Sh.O. .4 .4 .4 .4 38 .38 38 . 36 .4 AlO. l.4 .4 l.4 1.4 1.3 31 .34 1.24 1.4 ZnO 2.2 2.2 22 22 2.05 2.()5 2. () 95 2.2 TiO, .4 .4 .4 .4 38 38 38 36 .4 MnO, 23.4 23.4 23.4 23.4 23.4 23.4 23.4 23.4 23.3 CrO. 2 .6 .4 5 .5 5 5 .5 2 FeO. ------5. 5. -- 5.1 - CoO - - - - - 3.5 3.5 -

Ex. Ex. Ex. Ex. Ex. Ex. Ex. Ex. 14 15 6 7 18 19 2) 2 SiO, 5().8 5.9 49.52 53.1 52.3 5.4 51.4 54.6 N:O 6.4 6.6 6.3 6.7 6.6 6.5 6.5 6.9 KO 6.6 6.8 6.48 6.9 6.8 6.7 6.7 7. CO 6.3 6.5 6.2 6.6 6.9 6.4 6.4 6.8 SbO. .4 .4 38 .4 .4 .4 .4 .4 A.O. .4 1.4 1.34 1.5 1.4 1.4 .4 5 ZnO 2.2 2.2 2.1 () 22 2.2 2.2 2.2 2.3 g : TiO, .4 .4 38 .4 .4 .4 .4 .4 MnO, 23.2 191 19. 7.6 17.6 17.6 17.6 12.() NiO. - - u- - - - - 8 CrO. 2.3 - - 2.3 3.5 4.7 3.5 -- FeO. - -- -- 2.3 2.3 2.3 3.5 -

CuO - --- 3.5 - - - - - CuO - 4.7 4.7 - - - - -

35 The absorptive glass materials provided by this inven- Percent by Weight tion are very stable and are chemically and thermally - w compatibleatibl with conventionali-ar. glasses employed .in opti- SodiumSilicon DioxideOxicle (NaO) (SiO) .54.66.9 cal fibers. The absorptive glasses can be readily drawn 40 SSd 7. and redrawn into very thinan filaments of substantially?h rht Antimonyalciun Oxile Trioxide (CaO) (SbO) 6.8.4 uniform diameter and absorptive properties and can be Aluminum Oxide (AO) 5 readily drawn with and fused together with conven- fESE 'TiO, 2. tional optical fiberglass materials. The absorptive glass Manganese Dioxide (MnO,) 20 materials are also chemically compatible with phos phors and the like conventionally employed in cathode 45 ray tubes and the like. The absorptive glass can also be a 100 micron thickness of said glass material having an conveniently ground or polished even when embodied optical density greater than 0.25 at least for light from in faceplates or the like in the form of thin filaments. 0.4 to 0.6 microns wavelength. It will be understood that the specific examples of 50 3. A glass material having a calculated oxide compo glass composition have been set forth above by way of sition comprising illustration but that this invention includes all modifica tions and equilvalents thereof which fall within the scope of the appended claims. Percent by- Weight We claim: SS Silicon Dicxide (SiO) 61.6 1. A glass material having a calculated oxide- compo - - - SodiumPotassium Oxide Oxide (NaO) (KO) 7.88.() sition comprising Calciun Oxide (CO) 7.7 Antimony Trioxide (SbO) 5 Aluminum Oxide (AO) .7 Percent by Weight Zinc Oxide (ZnO) 2.6 Titanium Dioxide (TiO) 5 Silicon Dioxide (SiO.) 5.9 60 Nickelic Oxide (NiO) 6 Studium Oxide (NaO) 6.5 Cobalt Oxidic (CoO) 3.6 Potassium Oxide (KO) 6.8 Calcium Oxide (CaO) 6.5 Antimony Trioxide (SbO) ()-4 Aluminunn Oxide (Al...O. .4 a 100 micron thickness of said glass material having an Zinc Oxide (ZnO) 2. optical density greater than 0.25 at least for light from ManganeseTitanium Dioxicie Dioxide ( IiC))(MnO) 23.4(J.- 65 0.4.4 to O0.6 microns waveavel ength.h Chromium Oxide (CrO) {}.5 4. A glass material having a calculated composition Total (J().() comprising 3,904,425 7 8 Percent by Weight wherein a content of MnO, less than 20 percent is sup Silicon Dioxide (SiO.) 46.38 plemented by others of said colorants in order to Sodium Oxide (NaO) 5.85 achieve an optical density of at least 0.25 in a thickness Potassium Oxide (KO) 6.()5 Calcium Oxide (CaO) 5.78 of 100 microns at least for light from 0.4 to 0.6 microns Antimony Tricxide (ShO.) .3-4 5 wavelength. Aluminum Oxicie (AO) 1.29 Zinc Oxicle (ZnO) 97 6. A glass material having a calculated oxide compo Titanium Dicxicle (iO.) 3-4 sition comprising Manganese Dioxide (MnO, ) 23.4 Ferric Oxicic (F.O.) chalt Oxide (CoO) Percent by Weight Silicchi Dioxide (SiO) 46.04 to 54.6 Sodium Oxide (NO) 576 to 6.9 a 100 micron thickness of said glass material having an Potassium Oxidc (KO) 6. ()3 to 7. optical density greater than ().25 at least for light from Calcium Oxide (CaO) 5.76 to 6.8 0.4 to 0.6 microns wavelength. Antimony Trioxide (SbO) .34 to .4 Aluminum Oxide (AO) I.24 to 1.5 5. A glass material having a calculated oxide compo 5 Zinc Oxide (ZnO) .95 to 2.3 sition comprising Titanium Dioxide (TiO) 34 to 4

Percent by Weight Silicon Dixide (SiO.) 4() to 65 wherein the combined content of NaO and KO equals Sodium Oxide (NO) () ty. () at least 1 1.79 percent by weight, Pot:ussium Oxide (KO) () ty l() Calcium Oxicle (CaO) -4 to 9 said glass material including at least one colorant se Antinniny ricoxicle (Sb.O.) .3 to l() lected from the group consisting of Aluminunn Oxide (Al...O.) () toy 2 Zinc Oxide (ZnO } () to 3 Titanium Dioxide (TiO) () toy 2 2 5 Percent by Weight Manganese Dioxide (MnO) 12 to 23.4 Nickclic Oxide (NiO) () to 8 wherein the combined content of NaO and KO equals Chrynnium Oxide (CrO) () to 4.7 at least 1 () percent by weight, Ferric Oxide (FeO) () to 5. said glass material including at least one colorant se Cobalt Oxide (CoO) () to 3.5 lected from the group consisting of Cupric Oxide (CuC)) () to 47

Percent by Weight wherein a content of MnO, less than 20 percent is sup Manganese Dioxide (MnO, ) 12 to 32 Nickelic Oxide (NiO.) () to 9 plemented by others of said colorants in order to Chromium Oxide (CrO) () to ().5 achieve an optical density of at least 0.25 in a thickness Ferric Oxicle (FeO) () to 9 Chalt Oxide (CO) () to 6 of 100 microns at least for light from 0.4 to 0.6 microns Cupric Oxide (CuO) () to 9 wavelength. uuu-a-e-m-ram-m-or--" k ck sk ck sk

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