(12) Patent Application Publication (10) Pub. No.: US 2005/ A1

Transcription

1 (19) United States US A1 (12) Patent Application Publication (10) Pub. No.: US 2005/ A1 Hamilton et al. (43) Pub. Date: (54) LOW BORON E-GLASS COMPOSITION (52) U.S. Cl /35; 501/36; 501/70 (76) Inventors: James Patrick Hamilton, Parker, CO (US); Harry Hand Russell III, (57) ABSTRACT Evergreen, CO (US) Provided is a glass composition useful in preparing fiber Correspondence Address: glass, with the composition comprising SiO2 in an amount JOHNS MANVILLE ranging from weight percent: B.O. in an amount Legal Department ranging from weight percent, in an amount West Ute Avenue ranging from weight percent, in an amount Littleton, CO (US) ranging from weight percent; Al-O in an amount 9 ranging from weight percent; and Na-O in an amount (21) Appl. No.: 10/613,939 ranging from weight percent. The glass composition has an HTV of no greater than 2300 F. and a liquidus (22) Filed: Jul. 7, 2003 temperature at least 150 F. less than the HTV temperature. The composition allows one to realize costs Savings asso Publication Classification ciated with lower batch costs and abatement requirements, without Significantly increasing the energy required for (51) Int. Cl."... C03C 13/00; CO3C 13/06; melting the glass, reducing fiberization efficiency, or requir CO3C 3/087 ing the development of new bushing technology.

2 LOW BORON E-GLASS COMPOSITION BACKGROUND OF THE INVENTION 0001) 1. Field of the Invention 0002 The present invention relates to a low boron con taining E-glass composition. More specifically, the present invention relates to a glass composition which comprises a Small amount of boron, and Still maintains fiberization capability Description of the Related Art 0004 For many years, the industry has prepared fiber glass and fiberglass products with a base glass composition of the "E-glass' type. E glass is generally described in U.S. Pat. No. 2,344,961, and the described glasses are typified by the composition listed below (with the constitu ents being in weight percent): 52-56% 12-16% 16-19% 3-6% BO 9-11% 0005 U.S. Pat. No. 2,571,074 describes a modified E glass, which is typically devoid of, and with the content much higher than a typical E glass. In general, the glasses have a composition as shown below (the percentages being weight percent): Al-O % 12-16% 19-25% BO 8-13% 0006 U.S. Pat. No. 4,166,747 describes an Eglass which attempts to lower the BO content in the glass used to manufacture glass fibers in order to achieve reductions in batch costs. To compensate, the glass composition used has only a Small quantity of. In general, the glass has a composition as shown below (the percentages being in weight percent): 54 55%, more preferably % 13-14% 22-24%, more preferably % %, more preferably % BO %, more preferably % 0007 Thus, typical E-glass compositions used in the industry generally contained approximately 6% or more BO. As a result of this level of BO, abatement of E-glass furnaces is required to reduce particulate emissions into the environment. As a result of the challenging economics, and environmental issues, E-glass type fibers have been pro posed that contain little or no BOs, i.e., See, for example, WO 00/73231; WO 01/32576; U.S. Pat. No. 6,136,735 and U.S. Pat. No. 5,789,329. Benefits are claimed associated with lower abatement costs and lower batch costs due to boron-free base glass formulations The elimination of BO in the base glass compo Sitions, however, has resulted in increases in the high temperature Viscosity (HTV) and liquidus temperature rela tive to standard E-glass containing 6% or more B.O. HTV is the temperature at which the glass melt has a Viscosity of 1000 poises. In the production of fiberglass, the glass melt in the bushing is typically maintained at F. above the HTV for optimum fiberization efficiency. A glass com position with a higher HTV requires more energy to achieve this Viscosity and therefore, incurs higher energy costs. The liquidus temperature is the highest temperature at which devitrification (crystallization) of the glass melt occurs. In fiberglass production, it is greatly preferred that the glass melt be maintained at a temperature at least 150 F. above the liquidus to avoid crystallization problems and conse quently, lower fiberization efficiencies. It has been found that in the commercial production of E-glass fibers, fiber ization efficiency is significantly reduced as the difference between HTV and liquidus (referred to as delta ) falls below approximately 150 F Thus, it would be desirable to take advantage of the cost benefits associated with lower boron E-glass formula tions, but avoid the disadvantages of crystallization and fiberization problems. The challenge in producing Such a composition is developing the right combination of oxides that yields a glass with a suitable HTV and maintains a delta of at least 150 F., while utilizing a lower amount of boron. Providing Such a glass composition would be of exceptional value to the industry Accordingly, it is an object of the present invention to provide Such a glass composition which can be used to make useful continuous fiberglass Strands, which process is more economic to make, yet avoids major manufacturing problems associated with crystallization of the glass This and other objects of the present invention will become apparent to the skilled artisan upon a review of the following description and the claims appended thereto. SUMMARY OF THE INVENTION In accordance with the foregoing objective, pro Vided by the present invention is a glass composition having a reduced amount of boron which is useful in preparing continuous fiberglass Strands. The composition allows one to use a minimal amount of boron, yet provides a glass with a Suitable HTV and a delta of at least 150 F. above the liquidus temperature to avoid crystallization problems. The composition is thus cost effective and practical for use in preparing Eglass continuous Strands The glass composition has an HTV of no greater than 2300 F. and a liquidus temperature of at least 150 F. less than the HTV temperature. The composition comprises the following ingredients:

3 -continued It has been found that glass compositions employ ing the foregoing percentages can achieve a Suitable HTV of less than 2300 F. So that the process remains energy efficient and extraordinary bushings capable of withstanding higher fiberization temperatures are not needed. Further more, the glass compositions within the foregoing percent ages permit a difference between the HTV and liquidus temperature of at least 150 F., thereby permitting fiberiza tion efficiency. While enjoying the foregoing benefits, the compositions also reduce batch material costs considerably, as well as the abatement requirements due to the lower amount of BO contained in the glass composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The glass compositions of the present invention are characterized by an amount of B.O. which is less than that generally employed in industrial Eglass compositions, yet more than that contained in the compositions that have evolved containing Substantially no boron. Thus, the glass compositions of the present invention allows one to avoid the problems of fiberization efficiency and the need to use Substantially higher fiberizing temperatures, which can do damage to the bushing employed. To achieve good, con tinuous fiberglass Strands employing this lower amount of BO, and to have a suitable HTV of less than 2300 F. and a liquidus temperature at least 150 F. less than the HTV temperature, it has been found that the glass composition must also employ,, Al-O and Na-O within the following weight percentage ranges: Al-O The reduced BO content permits one to realize cost Savings associated with lower batch costs and abate ment requirements. At the Same time, employing the fore going glass composition allows one to also achieve the cost Savings without significantly increasing the energy required for melting the glass, a reduction in fiberization efficiency, or requiring a development of new bushing technology While the foregoing compositions must contain the ingredients noted, other ingredients may be present in the composition of ingredients. Such impurities are generally TiO, and Fe2O. In general, glass will contain TiO, in a range of from 0.4 to 0.6 wt.% as an impurity, and Fe2O in a range of from 0.2 to 0.3 wt.% as an impurity. As well, a small amount of K2O can be present as an impurity, for example, up to 0.5 wt.%. Generally, no LiO or F is found in the glasses of the present invention. Thus, while the glass composition described herein will relate to those ingredients important to achieving the objectives of the present inven tion, one of ordinary skill in the art will understand that impurities generally found in glass Such as TiO2 and Fe2O will be present in the glass to a limited extent In a preferred embodiment, the glass compositions of the present invention more preferably contain SiO in an amount ranging from about 53 to 57 weight percent; an amount of BO more preferably in the range of from about 4 to 5 weight percent, an amount of more preferably in the range of from about weight percent, an amount of more preferably in the range of from about weight percent; an amount of Al-O in the range of from about weight percent; and an amount of Na2O in the range of from about weight percent. Thus, a pre ferred composition would contain the following amounts of ingredients, BO wt.% 3-5 wt.% wt.% wt.% wt.% wt.% Most preferably, the amount of SiO ranges from about weight percent; the amount of BO most preferably ranges from about 4.5 to 5.0 weight percent; the amount of ranges from about weight percent; the most preferred amount of ranges from about weight percent; and the most preferred amount of Al-O ranges from about weight percent; and the amount of Na2O ranges from about weight percent In selecting the particular ingredients for the glass composition within the foregoing ranges, the HTV realized is generally less than 2300 F. Easily, however, the glass composition can be formulated to achieve an HTV less that 2250 F, and most preferably less than 2200 F. The liquidus temperature of the glass composition is at least 150 F. less than that of the HTV temperature, to therefore provide a delta T of 150 F. Thus, the liquidus temperature is generally at least below 2150 F, more preferably less than 2100 F., and most preferably less than 2000 F. Also, it is preferred that the delta T is also greater than 160 F The reduction of BO cannot simply be compen Sated for by the increase of another oxide in the glass composition. The combination of changes in the oxides is complex, and must be within the ranges discussed above. This selection must be made with an eye toward the HTV and liquidus temperature of the composition, for otherwise the advantages of the present invention are lost. Generally, Selecting and mixing oxides within the ranges discussed above will provide one with a glass composition that meets the HTV, liquidus and delta requirements for economically and efficiently preparing continuous fiberglass Strands In order to further illustrate the present invention, Several experimental runs were conducted in which glass compositions were experimentally melted and tested for HTV, liquidus and chemical composition. AS well, cost Savings per ton as opposed to typical commercial E glass was calculated. Table 1 below sets forth the specific examples of glass compositions.

4 TABLE 1. Examples of glass composition and properties for lower BO3-containing E-glass fibers Oxide (weight %) A. B C D O BO TiO, O.54 O.54 O.53 O.54 Fe2O3 O.22 O.22 O.22 O.23 KO O.O3 O.O3 O.O3 O.O3 HTV (F) Liquidus (F) Delta (F) Cost savings?ton vs. E-glass 216 S S S S It is clear from these experiments that in order to reduce the BO concentration in the glass formulation, it cannot only be Substituted for by a single oxide (e.g., 3% BO, vs. 3% SiO.). In order to maintain the required HTV and liquidus temperature, a combination of oxides must replace B.O. in the composition. Also, as the HTV increases over that of Standard E-glass which is common for those compositions of the prior art which contain Substantially no BO, and the same bushings are used for fiberization, bushing lifetime decreases and therefore adds costs that are not factored into the cost savings listed in Table 1, which and wherein the glass composition has an HTV of no greater than 2300 F. and a liquidus temperature at least 150 F. less than the HTV temperature. 2. The glass composition of claim 1, wherein the amount of SiO ranges from 53 to 57 wt.%. 3. The glass composition of claim 2, wherein the amount of B.O. ranges from 4 to 5 wt.%. 4. The glass composition of claim 1, wherein the amount of ranges from wt.%. 5. The glass composition of claim 1, wherein the amount of ranges from wt.%. 6. The glass composition of claim 1 wherein the amount of Al-O ranges from wt.%. 7. The glass composition of claim 1, wherein the amount of ranges from wt.%. 8. The glass composition of claim 1, wherein the com position contains the following amounts of ingredients: Savings are realized with the compositions of the present invention wt.% - 0 BO Other examples of suitable compositions within the CO wt.% present invention which provide the advantages of a Suitable wt.% HTV and a delta T are shown below in Table 2. TABLE 2 Example Al-O. B.O., HTV F. Liq. F. Delta T O O OO S.OO O Of 15.OO S.OO O O O O O 23OO.O 21S.O.O O O OO OO OO 4.OO O O.S O 2106.O. 15.O.O 9 58.OO O O O O 1.6O 2013 O.SO O : O While the present invention has been described in accordance with certain preferred embodiments, it will be -continued apparent to one of ordinary skill in the art that many changes an list Ca als t with sts wt.% rom Line Spirit or Scope OI. Ine Invenuon as Set Iorunnerein wt.%. What is claimed is: 1. A glass composition useful in preparing fiberglass, comprising: 9. The glass composition of claim 8, wherein the amount of SiO ranges from wt.%.

5 10. The glass composition of claim 8, wherein the amount of ranges from wt.%. 11. The glass composition of claim 10, wherein the amount of ranges from wt.%. 12. The glass composition of claim 8, wherein the amount of Al-O ranges from wt.%. 13. The glass composition of claim 1, wherein the HTV is less than 2250 F. 14. The glass composition of claim 1, wherein the HTV is less than 2200 F. 15. The glass composition of claim 1, wherein the liquidus temperature is at least 160 F. less than that of the HTV temperature. 16. The glass composition of claim 1, wherein the amount of BO ranges from 4.5 to 5.0 wt.%. k k k k k