[1]United States Patent Office 3,506@464 P a t e n t e d A p r . 1 4 , 1 9 7 0 2 content of 8 to 17 mole percent, a total SiO2+B203 content of 85 to 96 mole percent, and a total SiO2+AI203 content of 78 to 8 8 mole percent. The presently-preferred component ranges for the ingredients of the opal glasses of the present invention include a glass consisting essentially of 80 to 85 mole percent SiO2, 9 tO 11 mole percent B203, 1 to 3 mole percent A1203, 4 to 6 mole percent Na2O, and I to 6 mole percent P205; and a glass consisting essentially of 80i to 85 mole percent SiO2, 9 tO 11 mole percent B203, 4 to 6 mole percent Na2O, and I to 5 mole percent P205- In preparing the opal borosilicate glasses of the above compositional range, the batch ingredients are intimately mixed and heated to such temperature so that all substances are present in the liquid state, thereby enabling the formation of a glass from a homogeneous melt. The batch ingredients used for the subject glasses were mixed well by hand or in a commercially-available standard laboratory V-blender. The mixed batch materials were conveniently melted in a 90% platinum-10% rhodium crucible in an electrically heated furnace, at a temperature of 1500 to 1600' C. in an air atmosphere. The melts were heated at this temperature for 16 to 24 hours. After the melts had cooled to room temperature, they were usually crushed and remelted at 1500 to 1600' C. overnight, to insure homogeneity. The subject glasses prepared from the described melts generally exhibited melting and forming characteristics adaptable for the fabrication of glass items of commerce by standard conventional procedures. The batch materials employed for preparing the glasses were the high ptirity commercially-available materials and were selected from the following: SiO2 Kona Quintas Quartz, A1203 Alcoa A-14, B203 Baker purified reagent, AIP04 Fisher purified reagent and Fisher certified or Baker analyzed reagents: Na2CO3, NaPO3 and P205- The following examples are set forth as representative batch components and glasses prepared according to the spint of the present invention. These examples are not to be construed as limiting the scope of the invention as other functionally equivalent means will be readily apparent to those skilled in the art. Representative batch constituents for preparing the novel opal borosilicate glasses of the subject invention are set forth in Table I, - immediately below. TABLEI Batch constituents, grams I ngredients E x. 1 E x. 2 Ex. 3 E x. 4 Kona Quartz ----------- 310.54 71. 97 319.43 74.06 Alcoa A-14 ------------------------- 2.33 --------- --------------- B203 -------------------- 48.58 11.69 49. 06 11.80 Na2CO3 ---------------- 30. 24 7.28 20.37 7.35 P205 -------------------------------- 9. 75 ------------ 9.84 NlPO4 ------------------ 23. 20 ------------------- ----------------- AAPO@ ------------------------------------------ 19.60 ------------ The above batch ingredients, as set forth in the numbered examples, were melted at about 1600' C., for 16 to 20 hours in an air atmosphere. The melts were carried out in platinum-rhodium crucibles heated in an electric furnace. After cooling to room temperature, the freshly formed melts were crushed and remelted for about 16 hours at 1600' C. in an air atmosphere to insure homogeneous glass formation. In Table H, immediately below, the mole percent composition of Examples I to 4 are set forth as Exampes 5 to 8 respectively. The coefficient of expansion is listed for the glasses of Examples 5 to 7. Also the glass of Example 7 was heated to 440' C. for 70 hours to produce increased opalescence. Generally, in conventional opal glass, the thermal expansion raises with phase separation in said glass; however, the glass of Ex 3,506,464 OPAL GLASS COMPOSITIONS Nils Tryggve E. A. Baak, Ridgefield, Conn., and Charles F. Rapp, Toledo, Ohio, assignors to Owens-Illinois, Inc., corporation of Ohio 5 No Drawing. Filed June 17, 1966, Ser. No. 558,265 Int. Cl. C03c 3108 U.S. Cl. 106-54 7 Claims ]o ABSTRACT OF THE DISCLOSURE An opal glass composition wherein the glass consists essentially of 78 to 85 mole -percent SiO2, 7 to 1 1 mole percent B203, 0 to 6 mole percent A1203, 3 to 6 mole percent Na2O, and 1 to 6 mole percent P205. The glass has 15 a coefficient of thermal expansion within the range of 25 to 40x 10- 7/01 C. (0-300' C.). T'he present invention pertains to the glass art, and ' 20 more particularly, to novel glass compositions. Specifically, the instant invention relates to novel opal borosilicate glasses possessing a medium thermal coefficient of expansion. The principal object of the present invention is to pro- 2- vide novel glass compositions. A further object of this invention is to provide opal glass compositions. Yet a further object of the instant invention is to provide opal borosilicate glasses. 30 Still a further object of the subject invention is to effect opal glasses possessing relatively low thermal coefficient of expansion. Still further objects and advantages will be apparenit to those versed in the art from the detailed - disclosure and 35 claims which follow. According to the present invention, there is provided a novel family of opal glass compositions. The expression "opal glass" as used herein generally denotes glasses 40 which possess light diffusing properties or phases therein to render said glasses essentially light diffusing or endowed with translucent effects. The opal glasses of i@he subject invention have an expansion coefficient in the range of 25 to 4OX 10-7/1 C. (0-300' C.) with the now 4@' preferred range of about 30 to 35XIO-7/1 C. The opal 0 borosilicate family of the instant invention generally contains the acidic oxides of the R02 group, the R203 group, and the R205 group, and the alkaline oxide of the R20 group. The oxides of the above groups presently employed 5 0 in the subject glasses include the acidic oxides silicon dioxide, SiO2, boric oxide, B203, aluminum oxide, A1203, and phosphorus pentoxide, P205, and the alkaline oxide sodium oxide, Na2OThe components of the novel opal borosilicate glass .55 compositions, as set forth immediately below, are present in the following inventive proportions: a glass consisting essentially of 78 to 85 mole percent SiO2, 7 to 11 mole percent B203, 0 to 3 mole percent A1203, 3 to 6 mole percent Na2O, and 1 to 6 mole percent P20,5; a glass 60 composition consisting essentially of 78 to 85 mole percent SiO2, 7 to 11 mole percent B203, 4 to 6 mole percent Na2O, and 1 to 6 mole percent P205; a glass consist'mg of 78 to 85 mole percent SiO2, 7 to 11 mole percent B2,(Ds, I to 3 mole percent A1203, 3 to 6 mole percent Na2O, 65 and I to 6 mole percent P205; and a glass - consisting essentially of 78 to 85 mole percent SiO2, 7 to 11 mole percent B203, 3 to 6 mole percent P205, 0 to 3 mole percent A1203, and 3 to 6 mole percent Na2O. The subject glasses are further characterized by a total To B203+P205
[2]31506)464 3 ample 7 exhibited a decrease in thermal expansion, that is 29.4. TABLE II.-'@%IOLE PERCENT Ingredients Ex. 5 Ex. 6 Ex. 7 Ex. 8 5 SiO2 ------------------------------------ 81.5 78.5 83.0 so. 0 B203 ------------------------------------ 11.0 11.0 11.0 11.0 A1203 ----------------------------------- 1.5 1. 5---------------- Na2O ----------------------------------- 4.5 4.5 4.5 4.5 P205 ------------------------------------ 1.5 4.5 1.5 4. 5 CoefUcient of expansion (0-300' C.) ----- 32.3 -------- 35.1 -------- 10 The chemical composition, expressed in mole percent, for other representative glasses of the invention are listed in Table 111. The glasses were prepared as above described. TABLE II.-,MOLE PERCENT 15 Ingrediojits- -- Ex. 9 Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 SiO2 ---------- 81.5 so 78.5 83 81.5 so B203 ---------- 11 11 11 11 11 11 A]203 --------- 1. 5 1.5 1.5 ------------------------- ----- N',120 --------- 4. 5 4.5 4.5 4. 5 4.5 4. 5 20 P205 ---------- 1. 5 3.0 4. 5 1.5 3.0 4. 5 The subject glasses, in addition to possessing the inventive properties discussed above, are further characterized by their ability to become transparent at elevated tem- 1)5 peratures, that is at temperatures below the melting temperature. This is believed due to a different rate of change of the index of refraction with increasing temperature for two phases which apparently exist with said glasses. The lower index phase would exhibit greater change in 30 index of refraction than the higher index phase, so at an elevated temperature an apparent trarisparency is effected due to the apparently then-matched indexes. On cooling, the glasses regain their opal effects. Also, the present glasses have a thermal expansion of about 30x 10-7/1 C- 3r, in opposition to conventional opal glasses which possess thermal expansions of about 6OX 10-7/1 C. to 9OX 10-7/1 C. and are, therefore, suitable for the manufacture of heat-resistant ware. The thermal expansion of the subject glasses endows the glass with resistance to thermal break- 40 age, and they can be heated and cooled more quickly than glasses of higher expansion. The opal glasses of the present invention are employed in the fields of science, industry and commerce in the form of jars and bottles for therapeutic and cosmetic 4@ creams, for deodorant containers, li.-hting globes, cookware, heat-resistant ware, glass filters and the like. While the illustrative embodiments of the invention have been described with particularity, it will be understood that various modifications will be apparent and can 50 readily be made by those skilled in the art without departing from the scope and spirit of the invention. 4 We
