Glass compositions, fibers and methods of making same
United States Patent 1 Erickson et a1.  
 1 1 Apr. 8, 1975 1 GLASS COMPOSITIONS, FIBERS AND METHODS OF MAKING SAME [75] Inventors: Thomas D. Erickson, Newark;  
 Warren W. Wolf. Reynoldsburg. both of Ohio [73] Assignee: Owens-Corning Fiberglas Corporation, Toledo. Ohio [63] Continuation-in-part of Ser. No. 298.703. Oct. 18.  
 1972. abandoned.  
 [52] US. Cl 106/50; 106/52 [51] Int. Cl C03C 13/00; C030 3/04; C030 3/30 [58] Field Of Search 106/50. 52  
 [56] References Cited UNITED STATES PATENTS 2.394.493 2/1946 Schocnlauh i. 106/50 2.920.971 1/1960 Stookey 106/52 X 3.095.311 6/1963 von Wranau et a1. 106/50 3.540.893 11/1970 Petticrew 106/52 X 3.673.049 6/1972 Giffen et a1 106/52 X FOREIGN PATENTS OR APPLICATIONS 124.553 6/1947 Australia 106/50 908.074 10/1962 United Kingdom 106/50 217.609 5/1968 U.S.S.R i. 106/50 259.337 4/1970 U.S.S.R... 106/50 141.273 1/1961 U.S.S.R 106/50 Prt&#39;nmry E.\&#39;aminerPatrick P. Garvin Assistant E.\&#39;uminerMark Bc11 Attorney. Agent, or FirmCarl G. Staelin; John W. Overman; Raymond E. Scott [57] ABSTRACT Glass compositions are disclosed which are fiberizahle and are free of boron and fluorine. The compositions have the following range of proportions (by weight): SiO 55 to 6371; A1 0 11 to 18%; CaO. 9 to 2571; LL 0, 0.3 to 2.5%; TiO- 2 to 5%; MgO. 0 to 10%; MnO. 0 to 1.5%; Na O. K 0. 0 to 2.571; 8110. 0 to 2.5%: SrO. 0 to 1.5%. ZnO. 0 to 4%; ZrO 0 to 271; and Fe O 0 to 1%. wherein the total weight percent of U 0 and T10; is 3.5 to 6.5%. The preferred glass composition has a liquidus temperature of 2200F.. or less. and a viscosity of log 2.5 poises at 2450F.. or less.  
 7 Claims. No Drawings GLASS COMPOSITIONS. FIBERS AND METHODS OF MAKINGSAME This application is a continuation-iwpart of our copending application Ser. No. 298.703 filed Oct. l8. 1972, now abandoned.  
 BACKGROUND OF THE INVENTION This invention concerns fiberizable glass compositions which are free of boron and fluorine. Both boron and fluorine are potential air and water pollutants and for this reason are considered undesirable as components of glass compositions. particularly when the glasses are melted in gas-fired furnaces.  
  Glass fiber compositions which have been used to produce glass fibers suitable for use in textile applications generally contain boron and fluorine as fluxing agents. Boron is commonly put in the composition as colemanite. anhydrous boric acid or boric acid while fluorine is added as CilF-g or sodium silicofluoride (Na- SlFnl. Melting of the glass batch raw materials in gasfired furnaces to form molten glass from which fibers can be drawn and formed involves heating the batch and molten glass to temperatures in excess of 2200F. Commonly used textile glasses are melted in the range of 2400to 2750F At these melting temperatures B 0 and F or various compounds of boron and fluorine readily volatilize out of the molten glass and can be drawn up exhaust stacks and put into the atmosphere surrounding the glass fiber forming area.  
  The resultant air and perhaps water pollution can be reduced or eliminated by a number of approaches. Water scrubbing or filtering of exhaust gases can often clean up exhaust air. Use of electric furnaces in place of gas-fired furnaces will virtually eliminate the losses of volatile fluxes (e.g. boron and fluorine) commonly associated with gas-fired furnaces at temperatures above 2200F. These clean-up approaches however are often costly and can be avoided if the source ofthe pollutants. boron and fluorine. can be removed from the glass compositions. Complicating this solution however is the fact that removing boron and fluorine removes two commonly used ingredients in fiberizable. textile glass compositions. Maintaining acceptable melting rates. melting and operating temperatures. liquids and viscosity in the absence of boron and fluorine can be quite difficult.  
  An acceptable operating temperatures range in a commercial textile glass feeder or bushing is 22502500. A glass composition that will operate smoothly in this environment preferably should have a liquidus temperature of 2200F or less and a viscosity of Log 2.5 poises at a temperature of 2450F or less.  
  The fiber forming temperature is preferably about 100 fahrenheit greater than the liquidus temperature to avoid devitrification (crystal growth) in the glass as the fibers are formed. Since devitrification causes irregularities or seeds in the glass. which hamper or stop fiber production, the liquidus temperature of a commercial textile glass should be less than 2200F.  
  The viscosity of the molten glass is also a key to efficient and economical fiber forming. Glass viscosities of Log 2.5 poises at a temperature of 2450F or more re quire such high temperatures to melt the glass and make it flowable and formable into fibers that the metallic bushings of feeders sag and become unusable or must be replaced or repaired more frequently than when less viscous glasses are used.  
  With these problems in mind the boron and fluorine free. fiberizable glass compositions of this invention were developed.  
 SUMMARY OF THE INVENTION The glass composition of this invention substitutes 3.5 to 6.5% by weight U 0 and TiO. total for boron and fluorine as the fluxing agents in fiberizable glass compositions. U 0 and TiO in combination. have a synergistic affect on the preferred glass composition of this invention to lower the viscosity and liquidus temperature of the molten glass to within the preferred viberization range. In the glass composition of this invention. the concentration of Li O is 0.3 to 2.5)? by weight and 2.4 to 5&#39;7: by weight TiO The preferred glass composition also includes between about 2.5 and 3.5 percent by weight MgO. which further lowers the liquidus temperature of certain glass compositions. as shown in the Examples given below.  
  The glass compositions and glass fibers of this invention range within the following proportions. wherein the total weight percent of Li- -O and TiO- ranges from 3.5 to 6.5%. by weight:  
  Glass compositions falling within this range of proportions will be boron and fluorine free, have a viscosity of Log 2.5 poises at a temperature of 2450F or less and a liquidus temperature of 2200F or less. Glass compositions falling within the above range can be drawn into fine. continuous fibers having a diameter of about l5 X 10 to 55 X 10 inches.  
 DESCRIPTION OF THE INVENTION The glass compositions of this invention and the glass fibers made from them fall within the above broad range of ingredients. A preferred range of ingredients is as follows:  
 Ingredient [Percent by Weight Si0 56.7 to 59 M 0 12.2 to 14.6 (210 lb to 23 Li O 0.4 to 2.5 TiO- 7 to 5 MgO 2 to 3.5 R 0 (Na o, K 0) 0 to 0.8 BaO 0 to 2.5 ZnO 0 to 4 ZrO 0 to 2 Fe- O;, 0 to l the total weight percent of Li O and TiO in the above ranges from 3.5 to 6.5%. 6.5%. V  
 Suitable glass fibers consist essentially by weight of Percent Si()- 55 to 57 A1 13.5 to 14.5 (110 19.5 to 20.5 l.i- O 0.3 to 2.5 Ti()- 2 to 4.5 MgO 2 to 4 Na O 0.5 to l 11 0;. o 1 [U o s and wherein the total weight percent of U 0 and &#39;1i(). is 3.5 to 6.5%.  
  Specific glass compositions embodying the principles of this invention are described in the following Table 1, Examples 1 to 16.  
  The primary glass forming ingredients in the glass compositions of this invention are SiO. and A1 0 Lithia (Li- O) and Titania (TiO. are used in combi- TABLE 1 Example No. 1 Ingredient (Q by weight) No.2 No. No.4 No.5 No.6 No.7 No.8 No.9 No.10  
 Si(). 596 57.9 56.7 56.7 56.9 57.8 56.1 56.5 58.6 57 A1 0 14 14.1 14 14.1 14.1 14.1 17.9 13.9 13.8 14.1 (a0 17.7 19.2 19. 19.6 23.5 9.7 19.9 16.7 23 l.i. 1.2 1.2 1.2 1.2 1.2 0.4 2.4 1.1 1.2 1.5 TiO. 3.7 3.7 3.7 4.3 3.7 3.8 3.9 2.4 3.6 3.7 Mg() 2.8 3 3 3.1 3.2 9.2 3.1 2.6 M1 0 0.7 0.7 0.7 0.7 0.7 0.1 0.2 0.7 0.6 0.1 K 0 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.1 0.1 0.1 MnO 1.2  
  ZrO. 2 16.30 0.3 0.3 0.2 0.2 0.2 0.2 0.4 0.21 0.3 0.2 Liquidus: Temp..F. 2095 2100 2125 2115 2110 2150 2185 2175 2140 2150 Viscosity: Temp..F.  
  at Log Poise Example No.1 1 Ingredient 71 by weight) No.12 No.13 No.14 No.15 No.16  
  SiO- 57.5 57 59 62.8 57 57.3 A1 0 14.1 14.6 14.1 11.7 14.1 14 CaO 22.5 22.5 21 19.6 20 18.7 Li O 1.5 0.5 1.5 2.4 1.5 1.2 TiO 3.7 3.7 3.7 2.8 3.7 3.7 MgO 3.2 2.9 Na: 0 0.1 0.1 0.1 0.2 0.1 0.7 K 0 0.1 0.1 0.1 0.1 0.2 0.1 MnO BaO 1.2  
 ZrO  
  Fe. ,O; 0.2 0 3 0.3 0.3 0.3 0.2 Liquidus: Temp..F. 2135 2145 2140 2200 2145 2135 Viscosity: Temp..F.  
  211 Log Poise The viscosity determinations in Examples 1 through 16 were obtained using the apparatus and procedure described in U.S. Pat. No. 3.056.283 and in an article in The Journal of [he American Ceramic Society, Vol. 42. No. 1 1 November, 1950. pages 537-541. The article is entitled Improved Apparatus for Rapid Measurement of Viscosity of Glass at High Temperatures&#34; by Ralph L. Tiede. Other specific viscosity determinations referred to herein also would be measured by the apparatus and procedure described in the Tiede article.  
  The glass compositions of this invention, some of which are described in Table 1, Examples 1 through 16, have a liquidus temperature of 2200F or less and a viscosity of 10 poises (log poises 2.50) at a temperature of 2450F or less. These glasses are therefore nation in the glass composition of this invention as fluxes in place of boron and fluorine. The synergistic effect of the combination of U 0 and TiO to lower the viscosity of the glass composition, without adversely affecting the liquidus, is an important step in producing fiberizable glass compositions which are free of the potential pollutants. boron and fluorine. MgO may also be added to the glass composition to lower the liquidus temperature, if required, to Within the fiberization range. The preferred concentrations by weight of Li O and TiO are 0b 0.3 to 2.5% LL 0 and 2 to 5% TiO wherein the total weight percent of Li O and TiO is 3.5 to 6.5%.  
  Titania is marketed as a fine white powder, finding extensive use in paints to give opacity to enamels and the like. It is also used in glass decoration. Lithium carbonate (Li2CO3) manufactured from silicate minerals containing lithia. is the principle means of direct introduction of Li- O. The synergistic effect of Li O and TiO as described above. was quite unexpected from the teaching of the prior art.  
  Magnesium oxide (MgO) is generally considered a comparatively inert constituent of glass compositions and may be added by the raw materials. such as lime and dolomitic lime. MgO has also been known to have an effect on the melting temperature of certain glasses and is added to control the devitrification ofdiopesides (CaOmgOZSiO Lithia is the only one of the three commonly used alkali metal oxides (Li O. K and Na O) that can be used in amounts up to 4% by weight to control viscosity without adversely affecting liquidus. In the preferred glass composition of this invention. the range of Li- ,O is 0.3 to 2.5% by weight. Concentrations oflithia above 2.5% by weight. in combination with TiO- may cause a raising of the liquidus temperature to undesired levels.  
  Titania (TiO should be used in these glass composition in amounts of 5% by weight or less when used in amounts over about 5%. the TiO; cause the liquidus to reach undesired levels.  
  TlO-g in amounts over 5% can also cause a brownish tint or coloration of the glass fibers. This can be a prob lem where the fibers are combined with a clear matrix material and are visible in the final product. Clear plastic panels or clear plastic fishing rods are examples or products that might be less desirable if tinted fibers were used.  
  The alkali metal oxides Na. ,O and K 0 can be used individually or collectively to control viscosity. ln either case the total of Na O and K 0 should not exceed about 2.5% by weight and preferably not more than 1% by weight. Amounts of N320 and K 0 over 2.5% by weight causes an undesirable raising of the liquidus temperature. which outweighs the advantages these oxides have in keeping viscosity within the desired range.  
  In Examples 1-5. 8. 9 and 16, Nil-2O was added as a batch material. In the other Examples Na- ,O was not added intentionally but entered the glass compositions as an impurity in one of the batch raw materials. K 0 entered all ofthe Examples in Table l as a batch material impurity. Glass compositions with no K 0 or Na. ,O would fall within the scope of this invention.  
  Certain oxides of the RO group. namely BaO. CaO. MgO and MnO are beneficial additions to the glass compositions of this invention. SrO should be equally beneficial. The RO oxides are useful to control liquidus without adversely affecting viscosity. Best results have been found when these RO oxides are used collectively in amounts of 27% by weight or less.  
  Of the RO oxides listed above, best results are generally obtained when MgO and CaO are used. individually or in combination. It is believed that SrO used individually or in combination with CaO would give similar results.  
  MnO is preferably used in amounts of 0.5% or less. When used in amounts over 0.5%, MnO can cause a brownish or purple color in the glass composition and fibers.  
  It has also been found that ZrO in amounts up to 2% by weight can be used in the glasses of this invention to increase the chemical durability of the glasses. This increased durability is attributed to the fact that ZrO for some reason not fully understood. will inhibit the leaching out of alkali metal oxides from these glasses when the glasses are contacted by water. acids and the like. In this regard it is believed beneficial to add Zl Og to the glasses of this invention as the amounts of alkali metal oxides increases.  
  Fe O can enter these glass compositions as an impurity of the batch raw materials or it can be added intentionally in amounts up to 1% by weight. F620;; can however discolor the glass and fibers drawn from the glass. especially in combination with TiO and should therefore be kept as low as possible when clear glass fibers are required for some end use. In product applications where clear glass fibers are required. Fe O should be kept at 0.5% by weight or less. and preferably below 020.2% by weight when more than one percent TiO. is present.  
  Various other impurities or tramp materials may be present in the glass compositions of this invention in amounts of 0.1% or less by weight without adversely affecting the glasses or fibers. These impurities would include chromic oxide (C1 03). oxides of vanadium. sulfates and phosphates. They can enter the glass as raw material impurities or can be products formed by the chemical reaction of the molten glass with the furnace components.  
  The method of making the fiberizable glass compositions of this invention then consists of adding 0.3 to 2.5% by weight Li O and 2 to 5% by weight TiO to a boron and fluorine free glass composition consisting essentially of SiO. A1 0 and CaO in the proportions given above. where the total weight percent of Li O and TiO is 3.5 to 6.5% and melting the batch. The temperature of the molten glass is then reduced to within the fiberization range and fibers are drawn. The methods of fiberizing glass are described in the prior art patents. including U.S. Pat. No. 2.908.036, assigned to the Assignee of the instant application.  
  Modifications and variations within the scope of the appended claims are intended to be included.  
 We claim:  
  1. Fiberizable. boron and fluorine free glass compositions consisting essentially by weight of:  
 Percent SiO- 55 to 63 M 0 ll to I8 C 9 to &#34;5 Li ,O 0.3 to 2 5 TiO 2 to 5 MgO to 10 MnO 0 to 1.5 Na- O. K 0 0 to 2.5 BaO 0 to 2. SrO 0 to 1.5 2110 0 to 4 ZrO 0 to 2 Fe- Q 0 to I wherein the total weight percent of Li O and TiO is 3.5 to 6.5% and wherein the glass composition has a liquidus temperature of 2200F, or less, and a viscosity of log 2.5 poises at 2450F., or less.  
  2. The glass composition defined in claim 1, wherein the total weight percent of Na O, K 0 and U 0 is greater than one percent and the total weight percent of Na O and K 0 is less than 2.5 percent.  
 Percent SK): 50.7 10 A1 0 12.: to 14.0 (a0 to 33 [.1 0 11,4 10 2.5 l i(). I to 5 Mg() 3101.5 \;l:(). K- U to (1.1-1 HM) 1110 1.5 7.110 U to 4 /.r(). (l to I 1 0. (I to 1 wherein the total weight percent of U and &#39;l&#39;iO is 3.5 to 6.591 and wherein the glass composition has a liquidus temperature of 22(l()F. or less and a \&#39;iscosit of log 25 poises at Z-15UF. or less.  
  5. Boron and fluorine free textile glass fibers. consisting essentiall 1w weight of:  
 Percent Si(). 55 lo (r3 w o. 11 n 1s (:10 to Z5 Ii- 0,} to 1.5 no 2 to 5 MgO (I to ll) MnO (1 to 1.5 .o |\1 ,o o to Bad) (I to 2.5 Sr() (J In 1.5 7.n() U to 4 Zr(). (l to 2 l t- 0 U to l and wherein the total weight percent of the oxides Li- .O and &#39;l&#39;i()- is 3.5 to 6.5% and wherein the glass composition has a liquidus temperature of 22()()F. or less and a viscosity oflog 2.5 poises at 2450F. or less.  
  8 6. Textile glass fibers consisting essentially by weight of:  
 Percent Si() 55 to 57 A1 0; 13.5 to 14,5 CaO 19.5 to 30.5 U 0 0.; to 2.5 TiO 2 to 4.5 MgO Z to 4 Na O (1,5 to I 11- 0; (1.1 100.5  
 and wherein the total weight percent of Li O and TiO is 3.5 to 6.5 2.  
  7. The method of making a fiberizable glass composition. by adding 0.3 to 2.5% by weight U 0 and 2 to 5% by weight TiO: to the following boron and fluorine free glass composition. consisting essentially of. by weight:  
 Percent $10 55 tn ()3 A1 0 11 to 13 (:10 to 25 Mg() (1 to H1 MnO 1) to 1.5 N0 0. K- 0102.5 3:10 (I to 2.5 Sr() ll to 15 [n0 o to 4 -(ontinued Percent ZrO U to 2 Fc fl (I to l and wherein the total weight percent of U 0 and TiO is 3.5to 6.5%. and melting said glass composition and wherein the glass composition has a liquidus temperature of 2200F. or less and a viscosity of log 2.5 poises