FI56519C - BOR- OCH FLUORFRASE GLASKOMPOSITION FOER BILDNING AV GLASFIBRER - Google Patents

Description

R5FH [B] (11) ANNOUNCEMENT CCC1Q

jfllgflA lJ 1 'UTLÄGGN I NGSSKR1 FT 003' S * ^ (51) Kv.lk. * / lnt.CI. 'C 05 C 1J / 00 ^ (JOM | - FINLAND (21) Patent application - PatentansBkninf 771070 (22) Application cloud - Ansttknlngsdag lU.06.77 (23) Alkupllvi — Glltlghctsdag 27 · Oh.73 (41) Become Public - Bllvlt offentllg lh.06.77

Patent and Registration Board. „, *, .....

'(44) Date of issue and date of publication. -

Patent and registration authorities in the United States of America and the Publications Office 31.10.79 (32) (33) (31) Pyydetty etuoikeus — Begird prlorltet 28.0 ^ .72 28.01+. 72, 11.09.72 US A (US) 21 + 8360, 21 + 8U1 + 1 +, 288193 (71) Owens-Corning Fiberglas Corporation, 608 Madison Avenue, Toledo,

Ohio, USA (72) Thomas David Erickson, Newark, Ohio, Warren Walter Wolf, Reynoldsburg, Ohio, Ralph Lester Science, Granville, Ohio, John Allen Williams, Heath, Ohio, USA (7 ^ +) Berggren Oy Ab (5I +) Boron-fluorine-free glass alloy for forming glass fibers - Bor- och fluorofri glaskomposition för bildning av glasfibrer (62)

Fibrous glass alloys currently contain boron- or fluorine-containing compounds as fluxes, which reduce the viscosity of the charge, especially during the early stages of melting. Since boron and fluorine have been found to be potent environmental toxins, the problem has been to produce a glass alloy that (1) has the physical properties required for defibering, (2) is acceptable to the industry, and (3) is free of fluorine and boron.

For example, E-glass, which is the most common of the glass alloys currently used to make textile fibers, contains 9-11% by weight and may contain fluorine as a flux. The quality requirements for e-glass fibers also stipulate that the percentage of alkali metal oxides, namely Na 2 O, K 2 O 3 and L 2 O 2, must be less than 1% by weight, calculated as Na 2 O. Therefore, it is important to keep the alkali metal oxide level of glass alloys at or below 1% when developing new glass alloys that can be used in place of E-glass. The composition of the e-glass is disclosed in U.S. Patent No. 2,334,961.

2 56519

Boron is generally fed to the batch mixture as cholemanite, anhydrous boric acid or boric acid, while fluorine is added as CaF 2 or sodium silicofluoride (Na 2 SiFg). The melting of the raw materials of the glass charge, for example in gas kilns to form molten glass, from which the fibers can be drawn and formed, takes place by heating the charge and molten glass to temperatures above 1200 ° C. Commonly used textile fibers are melted between 1315-1510 ° C. In these melting temperatures, and various compounds of F2 or boron and fluorine tend to evaporate from the molten glass and the gases can become drawn into the exhaust chimneys and escape into the air surrounding the glass fiber formation area.

The resulting air and potential water pollution can be reduced or eliminated in many different ways. Water washing or filtration of the exhaust gases can often clean the exhaust air. The use of electric furnaces instead of gas burners effectively eliminates the losses of volatile fluxes (e.g. boron and fluorine) commonly associated with gas burners at temperatures above 1200 ° C. However, these cleaning agents are often expensive and can be avoided if the source of environmental toxins can be removed from the glass mixtures. However, this solution is complicated by the fact that the removal of boron and fluorine removes the two flux components commonly used in fibrous textile glass compositions. Maintaining acceptable melting rates, melting and operating temperatures, liquid form, and viscosity without boron and fluorine has been found to be quite difficult.

The acceptable range for use in a commercial textile glass feed channel or passage is between 1230-1370 ° C. The glass mixture operating uniformly in this environment preferably has a liquefaction temperature of about 1200 ° C or lower and a viscosity of log 2.5 poise or less at 1315 ° C.

The fiber formation temperature is preferably about 55 ° C higher than the liquefaction temperature to prevent devitrification (growth of crystals) in the glass when the fibers are formed. Because devitrification causes irregularities or beads in the glass that interfere with or can stop fiber production, the liquefaction temperature of commercial textile glass should preferably be below about 1200 ° C.

The viscosity of glass is also the key to efficient and economical fiber formation. Glass viscosities of log 2.50 poise at 3,56519 or above at 1340 ° C require temperatures so high to melt the glass and make it a flowable and malleable fiber that metal bushings or feed openings can collapse and become unusable or need to be replaced. or repaired more frequently than bushings that come into contact with less viscous glasses.

With these problems in mind, the boron- and fluorine-free, fibrous glass compositions and methods of this invention were developed.

The glass composition of the present invention is a boron and fluorine-free glass composition which is defiberable to form glass fibers and has a viscosity of log 2.5 poise at a temperature of 1345 ° C or less and is mainly characterized in that it contains mainly Ingredient.

SiO 2 54.5-60 Al 2 O 3 9-14.5

CaO 17-24

TiO2 2-4

MgO 1.5-4 RO 1-5.5

Na20 0-1 K20 0-1

Li 2 O 0-0.3

Fe 2 O 3 0-1 where RO is ZnO, SrO or BaO, and the amount of RO is calculated as ZnO.

The glass alloy according to the invention is a low-alkali glass alloy in which the concentration of alkali metal oxide is less than one% by weight. The low-alkali glasses of the present invention can directly replace E-glass, which is currently the most common glass alloy of textile fibers, as discussed above.

The glass mixture according to the invention contains a mixture of the three basic components described above, including SiO 2, Al 2 O 3 and CaO, as well as 2-4% TiO 2, 1.5-4.0% MgO and 1-5.5% RO, where RO is an oxide selected from the group consisting of ZnO, SrO and BaO, calculated as ZnO. The addition of ZnO, SrO or BaO has the effect of further lowering the liquefaction temperature and lowering the required TiO 2 concentration in the six-component glass mixture of this invention. Reducing the concentration of TiO 2 is important because TiO 2 is associated with Fe 2 O 3, which is added to the batch with the raw materials to form a yellow or brown 4,56519 color in the resulting fiber, which may cause difficulties in certain applications, as described below.

The glass mixture described above is free of boron and fluorine and has a viscosity of log 2.5 poise or less at a temperature of about 1340 ° C and a liquefaction temperature of about 1300 ° C or less. Glass alloys falling into the above range can be drawn into a fine continuous fiber having a diameter of 3.8 to 14.

The fibrous, six-component glass composition and method of the present invention eliminates the potent environmental toxins of boron and fluorine and the problems associated with the four- and five-component glass compositions described above. The color of the fibers formed from the further improved six-component glass mixture can be successfully compared to e.g. E-glass, and the physical properties, including the liquefaction temperature and viscosity, are in the range recommended for fiberization. The six-component glass composition of this invention contains substantially 54.5-60% SiO 2, 9-14.5% Al 2 O 3, 17-24% CaO, 2-4% TiO 2, 1.5-4 % MgO and 1-5.5% RO, wherein RO is an oxide selected from the group consisting of ZnO, SrO and BaO calculated as ZnO. The recommended concentrations of SrO and BaO in the six-component glass mixture are calculated as the corresponding weight percentages of ZnO.

As indicated above, the preferred composition of the six-component glass mixture contains less than one weight percent of alkali metal oxides, especially Na 2 O, K 2 O and Li 2 O, calculated as total Na 2 O. The process for producing boron- and fluorine-free textile glass fiber thus comprises melting a six-component glass mixture of the present invention to obtain molten glass having a viscosity of log 2.5 poise or less at 1340 ° C and a liquefaction temperature of about 1200 ° C, lowering the molten glass temperature to the defibering range. and fiber drawing.

Typical examples of the six-component glass mixture of the present invention are shown in the following Table 1, Examples 1-24.

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The viscosity determinations of the above examples were performed using the equipment and methods disclosed in U.S. Patent No. 3,056,283 and in The Journal of the American Ceramic Society, Vol. 42, No. 11, November 1959, pages 537-541. The article is entitled "Improved Apparatus for Rapid Measurement of Viscosity of Glas at High Temperatures" and was written by Ralph L. Science. Other separate viscosity determinations referred to herein may be measured using the equipment and methods described in the Ti.ede article.

The glass compositions of this invention, some of which are described in the tables above, preferably have liquefaction temperatures of 1200 ° C or lower, a viscosity 3a of log 2.50 poise (i.e., 10 'poise) or less at 1340 ° C. Glass containing less than 1% by weight of alkali metal oxides is therefore suitable for fiber formation, and direct replacement of E-glass and the corresponding boron- and fluorine-containing textile glass-fiber-forming glasses with boron- and fluorine-free glass is therefore possible.

All the glass alloys in Table 1 contain 1% by weight or less of the alkali metal oxides described above, and thus these glasses in their fibrous form are acceptable to consumers who require low alkali metal oxide contents, such as E-glass. The primary glass-forming components in the glass compositions of this invention are SiO 2 and Al 2 O 2. The three basic oxides of glass alloys are SiO 2, Al 2 O 2 and CaO.

Titanium dioxide (TiO 2) is used in the glass compositions of this invention as a flux instead of boron and fluorine. TiO2 is sold as a fine white powder, which is widely used in paints to give opacity to enamels, etc. It is also used in glass decoration, however, the use of TiO2 as a substitute for B202 and F2 to reduce the viscosity of defibering glasses without affecting adversely affected the temperature of the liquid form, was quite surprising.

TiO 2 should be used in these mixtures in amounts of 6% by weight or less, preferably less than 3.5%. Titanium dioxide concentrations above 6% by weight cause the liquefaction temperature to rise to undesired levels. Further, concentrations of TiO 2 of more than 4% can cause a brownish or yellowish color in the glass fibers. This can be a problem when the fibers are combined with a clear base material and are visible in the final product. Clear plastic sheets or clear plastic fishing rods are examples of products that may be less desirable if dyed fibers are used.

The concentration of MgO in the six-component glass mixture is preferably less than 4% by weight. Concentrations of MgO above 4% raise the temperature of the liquid form above the recommended limit for defibering. MgO can be added to the glass mixture with the raw materials and is known to have an effect on e.g. the melting temperature of E-glass and is added to E-glass to control the crystallization of diopsides (CaOMgOSiCl 2). It has now been found that 1.5-4.5% by weight of MgO lowers the liquefaction temperature and adjusts it to the defibering range and, as discussed above, reduces the amount of TiO 2 required in the mixture, which improves the color of the fibers. It can be seen from the examples in Tables 2 and 3 that MgO mainly replaces CaO.

The glass alloys shown in Table 1 contain ZnO, SrO or BaO to replace some of the TiO 2 used in the six-component glass alloy. This reduces or eliminates discoloration of the fibers and the addition of these oxides also lowers the liquefaction temperature and viscosity. The six-component glass composition of the present invention thus forms a complete substitute for E-glass without the strong environmental toxins boron and fluorine. The effect of ZnO, SrO and BaO in lowering the liquefaction temperature and lowering the required TiO 2 content in the six-component glass composition of this invention was not expected based on previous teachings in the art and is considered an important advance in the production of fibrous boron and fluorine free glass compositions. .

Fe 2 O 3 is present in all of the glass compositions of the present invention as an impurity in the feedstock or may be intentionally added up to one weight percent. However, Fe 2 ° 3 can dye the glass and the fibers drawn therefrom, as described above, and therefore its amount should be kept as low as possible when clear glass fibers are required for some application, especially when TiO 2 is present. Various other impurities or adventitious materials may also be present in the glass compositions in amounts of about 0.3% by weight or less without adversely affecting the glasses or fibers. These impurities include chromium oxide (C 2 O 2), vanadium oxides and phosphates. These substances may enter the glass as impurities in the raw materials or may be products formed in a chemical reaction between molten glass and furnace components.

Claims (4)

10 56519 between the road. Sulfur oxides may also be present in very small amounts, either as feed impurities or as deliberate additions of sulfates as finishing agents. A mixture of boron and fluorine-free glass which can be defibered to form glass fibers and has a viscosity of log 2.5 poise at a temperature of 1345 ° C or less, characterized in that it contains mainly Ingredient Weight% SiO 2 54.5-60 Al 2 O 3 9-14 .5 CaO 17-24 TiO2 2-4 MgO 1.5-4 RO 1-5.5 Na2O 0-1 k2o 0-1 Li2O 0-0.3 Fe2O3 0-1 wherein RO is ZnO, SrO or BaO, and The amount of RO is calculated as ZnO. Glass mixture according to Claim 1, characterized in that the sum of the amounts of Na 3 O, K 2 O and Li 2 O is less than 1% by weight, calculated as Na 2 O. 1. A composition of fluorine and fluorine which comprises a glass fiber with a viscosity and a viscosity of log 2.5 of 1345 ° C or more, which can be used to obtain a mixture of Vick-% SiO2 54, 5-60 Al 2 O 3 9-14.5 CaO 17-24 TiO 2 2-4 MgO 1.5-4 RO 1-5.5 Na 2 O 0-1