GLASS-FIBER COMPOSITIONS

Abstract: A biologically degradable mineral-fiber composition characterized by the following constituents in percent by weight: SiO2 50 to 60; Al2O3 less than 2; CaO + MgO 10 to 16; Na2O + K2O 14 to 19; B2O3 7 to 16; TiO2 0 to 4; ZrO2 0 to 5; ZnO 0 to 5; MnO 0 to 4; BaO 0 to 5; TiO2, ZrO2, ZnO, MnO, BaO 1 to 6; Fe2O3, SrO 0 to 2; F, Li2O 0 to 2; P2O3 0 to 4.

Description: Glass-fiber compositions The present invention relates to a glass-fiber compo¬ sition that is biologically degradable. The prior art describes some glass-fiber compositions which are said to be biologically degradable. The biological degradability of glass-fiber composi¬ tions is of great importance because various studies point out that some glass fibers with very small diameters in the range of less than 3 microns may be carcinogenic, while biologically degradable glass fibers of such dimensions show no carcinogenicity. However not only the biological degradability is of crucial importance but also the mechanical and thermal properties of the glass fibers, or the products produced therefrom, the resistance of the glass fibers and the proc- essibility of the glass-fiber composition. For example glass fibers are used to a great extent for insulation purposes. For these applications sufficient moisture-resistance is necessary. Also, the glass-fiber composition must permit process- ibility by known methods for producing glass fibers with a small diameter, for example the centrifugal technique, in particular the inner centrifugal technique (this technique is described for example in US-PS 4 203 745). The invention is based on the problem of providing a novel glass-fiber composition that is characterized by bio¬ logical degradability, has good stability or resistance to moisture and is easy to process. The invention is based on the finding that this problem can be solved by a glass-fiber composition that comprises considerable amounts of alkali oxides and boron oxide, and contains titanium oxide, zirconium oxide, zinc oxide, man¬ ganese oxide, barium oxide or mixtures of two or more of these oxides. It has turned out that such a glass-fiber composition fulfills the combination of the necessary properties, namely biological degradability, resistance to moisture and good processibility. The object of the invention is a glass-fiber composi¬ tion that is biologically degradable, characterized by the following constituents in percent by weight: SiO 2 CaO + MgO ZrO 2 ZnO MnO Bao TiO 2, ZrO2, ZnO, MnO, BaO The inventive glass-fiber compositions are processible by the centrifugal technique. The obtained fibers have good resistance to moisture. Surprisingly enough, the glass-fiber compositions show biological degradability. The mean fiber diameter is preferably 10 microns or less and is in partic¬ ular between 2.5 and 5 microns. According to a preferred embodiment the inventive glass-fiber composition contains 1 to 4 percent by weight titanium oxide. According to another preferred embodiment the composi¬ tion contains 1 to 4 percent by weight manganese oxide. According to another preferred embodiment the composi¬ tion contains 1 to 4 percent by weight zinc oxide. According to another preferred embodiment the composi¬ tion contains 0.5 to 5, in particular 0.5 to 3, percent by weight zirconium oxide. According to another preferred embodiment the composi¬ tion contains 0.5 to 4 percent by weight barium oxide. In particular it is preferred to use mixtures of the oxides zirconium oxide, zinc oxide, titanium oxide, barium oxide and manganese oxide, in particular mixtures of two or three of these oxides. Preferred embodiments are barium oxide in an amount of 1 to 4 percent by weight mixed with titanium oxide or zinc oxide. In further preferred embodiments zinc oxide is mixed with titanium oxide and optionally additionally zirconium oxide, whereby the constituents may each be present in amounts of 1 to 3 percent by weight. Further preferred embodiments are mixtures of zirconium oxide with zinc oxide, titanium oxide, barium oxide or man¬ ganese oxide, the constituents being present in amounts of 0.5 to 4 percent by weight, in particular 0.5 to 1.5 percent by weight. With compositions containing zirconium oxide and/or barium oxide it is advantageous if the composition also contains 0.5 to 2 percent by weight fluorine and/or lithium oxide. Aluminum oxide can be present in an amount of at least 0.1 percent by weight and in particular at least 0.5 percent by weight. Phosphorus pentoxide increases biological degradabil¬ ity. The compositions preferably contain 0.1 to 2 percent by weight P 20Ξ. According to a further preferred embodiment the compo¬ sition contains less than 2 percent by weight magnesium ox¬ ide. The moisture-resistance of the inventive glass-fiber compositions was determined by a standard method known as the DGG method. In the DGG method 10 g finely ground glass with a grain size between about 360 and 400 microns is held at the boiling point for five hours in 100 ml water. After quick cooling of the material the solution is filtered and a certain volume of the filtrate evaporated to dryness. The weight of the thus obtained dry material permits the amount of glass dissolved in the water to be calculated. The amount is stated in milligrams per gram of tested glass. The biological degradability of the inventive glass compositions was tested by introducing 1 g of the glass powder, as described for the DGG method, into a physiologi¬ cal solution with the composition stated below and a pH value of 7.4: NaCl 6.78 NaHCO 3 2.268 (Na 3 citrate) 2H20 0.059 Glycine 0.450 Dynamic test conditions were selected as are described in Scholze and Conradt. The flow rate was 300 ml/day. The duration of the test was 14 days. The results are stated as percent of SiO in the solution x 100 after 14 days. The invention shall be described in more detail in the following with reference to examples. Examples Glass with the compositions stated in Tables I and II was melted. All glass compositions could be processed satisfacto¬ rily by the centrifugal technique. The second last line states the values determined by the DGG method. The last line states the values of biologi¬ cal degradability according to the method of determination described above. Table I DGG 45 45 40 40 40 35 35 30 30 30 30 25 50 35 20 Biol . degrad- ability 500 550 500 550 600 550 600 450 450 500 550 500 550 450 450 Table II Examples ! . 17 IS . Si0 2 54 53.9 52.7 55.0 A1 2 0 3 0.5 0.4 0.5 0.5 CaO 8.5 8.5 8.0 8.0 MgO 1.8 1.5 1.8 1.5 Na 2 0 18.0 18.0 17.3 16.0 K 2 0 0.7 0.7 0.7 0.5 B2O3 13.5 13.0 14.0 12.5 Ti0 2 2.0 2.0 MnO ZnO 3.0 Zr0 2 2.0 2.0 BaO 3.0 P2O5 Fe 2 0 3 Sr0 2 F _ i 2 Ω_ 0.4 0.4 Impurities 1.0 1.0 0.6 0.6

Claims: Claims 1. A glass-fiber composition that is biologically de¬ gradable, characterized by the following constituents in percent by weight: SiO 2 CaO + MgO ZrO 2 ZnO MnO BaO TiO 2, ZrO2, ZnO, MnO, BaO F, Li 0 2 2. The glass-fiber composition of claim 1, character¬ ized in that the content of titanium dioxide is 1 to 4 per¬ cent by weight. 3. The glass-fiber composition of claim 1, character¬ ized in that the content of manganese oxide is 1 to 4 per¬ cent by weight. 4. The glass-fiber composition of claim 1, character¬ ized in that the content of zinc oxide is 1 to 4 percent by weight. 5. The glass-fiber composition of claim 1, character¬ ized in that the content of zirconium oxide is 0.5 to 3 percent by weight. 6. The glass-fiber composition of claim 1, character¬ ized in that the content of barium oxide is 0.5 to 4 percent by weight. 7. The glass-fiber composition of claim 1, character¬ ized in that if the composition contains zirconium oxide and/or barium oxide it also contains 0.5 to 2 percent by weight fluorine and/or lithium oxide. 8. The glass-fiber composition of claim 1, character¬ ized in that the composition contains barium oxide mixed with zirconium oxide, zinc oxide, titanium oxide and/or manganese oxide. 9. The glass-fiber composition of claim 1, character¬ ized in that the composition contains zirconium oxide mixed with zinc oxide, titanium oxide, barium oxide and/or manga¬ nese oxide. 10. The glass-fiber composition of claim 1, character¬ ized in that the composition contains less than 2 percent by weight magnesium oxide.

Inventors: DE MERINGO ALAIN, HOLSTEIN WOLFGANG, MAUGENDRE STEPHANE, ROUYER ELISABETH, DE MERINGO, ALAIN, HOLSTEIN, WOLFGANG, MAUGENDRE, STEPHANE, ROUYER, ELISABETH
Applicants: HOLSTEIN WOLFGANG, MAUGENDRE STEPHANE, MERINGO ALAIN DE, ROUYER ELISABETH, SAINT GOBAIN ISOVER, DE MERINGO, ALAIN, HOLSTEIN, WOLFGANG, ISOVER SAINT-GOBAIN, MAUGENDRE, STEPHANE, ROUYER, ELISABETH
Application year: 1995
Main classification: C03C13
IPC codes: C03C13