GLASS-FIBER COMPOSITIONS

Abstract: A biologically degradable mineral-fiber composition characterized by the following constituents in percent by weight: SiO2 45 to 60; Al2O3 less than 2; CaO + MgO 10 to 16; Na2O + K2O 14 to 20; B2O3 7 to 18; P2O5 0 to 4; BaO 1 to 5; Ti, Zr, Zn, Sr, Fe, Mn oxide 0 to 1.5; Diverse up to 0.5.

Description: Glass-fiber compositions The present invention relates to a glass-fiber composi¬ tion 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 are suspected to be carcinoge¬ nic, while biologically degradable glass fibers of such di¬ mensions 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 processibility of the glass-fiber composition. For example glass fibers are used to a great extent for insulation pur¬ poses. 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 substan¬ tially has considerable amounts of alkaline-earth oxide, alkali oxide and boron oxide and also contains barium oxide. It has turned out that such a glass-fiber composition fulfills the combination of the necessary properties, namely RECTIFIED SHEET (RULE 91) ISA EP 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 45 to 60 2 CaO + MgO 10 to 16 BaO 1 to 5 Ti, Zr, Zn, Sr, Fe, Mn oxide 0 to 1.5 Diverse 1up to 0.5. 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 less than 10 microns and is in par¬ ticular between 2.5 and 5 microns. The inventive glass-fiber compositions preferably have the following constituents in percent by weight: CaO + MgO 10 to 13 Na O + K 0 14 to 18 2 2 1.5 to 3 Ti, Zr, Zn, Sr, Fe, Mn oxide 0 to 1.5 Diverse up to 0.5 According to a further preferred embodiment the inven¬ tive glass-fiber compositions have the following constitu¬ ents in percent by weight: Al 203 lesε ; than 2 CaO + MgO 10 to 14 BaO 3 to 5 Ti, Zr, Zn, Sr, Fe, Mn oxide 0 to 1.5 Diverse up to 0.5. Barium oxide has a positive influence on moisture-re¬ sistance and presumably also on biological degradability. The inventive compositions can contain up to 1.5 per¬ cent by weight titanium oxide, zirconium oxide, zinc oxide, strontium oxide, lithium oxide, iron oxide and/or manganese oxide. Mixtures of 2 or 3 of these oxides are particularly preferred. Phosphorus oxide is preferably present in an amount of 0.1 to 2 percent by weight, in particular 0.3 to 1.5 percent by weight. Phosphorus oxide has a positive influence on biological degradability. According to a preferred embodiment the composition contains less than 2 percent by weight magnesium oxide. 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 NH Cl 0.535 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 2 in the solution x 100 after 14 days. The invention shall be described in more detail in the following with reference to examples. Example 1 A glass of the following composition in percent by weight was melted: SiO 57.5 2 CaO 8.0 MgO 3.5 Na 2 0 15.8 K 0.2 20 B O 12 . 0 2 3 BaO 2 . 0 Diverse 0 . 5 . These glass compositions could be processed by the centrifugal technique. Using the above-described DGG method a value of 40 was determined. The above-described test for biological degradability yielded a value of 500. Example 2 A glass with the following composition in percent by weight was melted: CaO 8.0 MgO 3.5 Na 2 0 15.8 BaO 2.0 Diverse 0.5. These glass compositions could be processed by the centrifugal technique. Using the above-described DGG method a value of 40 was determined. The above-described test for biological degradability yielded a value of 600. Example 3 A glass with the following composition in percent by weight was melted: CaO 7.0 MgO 2.0 BaO 2.0. These glass compositions could be processed by the centrifugal technique. Using the above-described DGG method a value of 20 was determined. The above-described test for biological degradability yielded a value of 500. Example 4 A glass with the following composition in percent by weight was melted: sio 2 57.2 Al O 2 3 0.8 CaO 8.0 MgO 1.5 Na 2 o 17.5 K 0 0.5 2 B O 13.0 2 3 BaO 1.5. These glass compositions could be processed by the centrifugal technique. Using the above-described DGG method a value of 20 was determined. The above-described test for biological degradability yielded a value of 600.

Claims: Claims 1. A glass-fiber composition that is biologically de¬ gradable, characterized by the following constituents in percent by weight: CaO + MgO 10 to 16 Bao 1 to 5 Ti, Zr, Zn, Sr, Fe, Mn oxide 0 to 1.5 Diverse up to 0.5. 2. The glass-fiber composition of claim 1, character¬ ized by the following constituents in percent by weight: CaO + MgO 10 to 13 BaO 1.5 to 3 Ti, Zr, Zn, Sr, Fe, Mn oxide 0 to 1.5 Diverse up to 0.5 3. The glass-fiber composition of claim 1, character¬ ized by the following constituents in percent by weight: CaO + MgO 10 to 14 Na 20 + K20 14 to 17 Bao 3 to 5 Ti, Zr, Zn, Sr, Fe, Mn oxide 0 to 1.5 Diverse up to 0.5 4. The glass-fiber composition of any of claims 1 to 3, characterized in that the composition contains up to 1.5 percent by weight titanium oxide, zirconium oxide, zinc ox¬ ide, strontium oxide, lithium oxide, iron oxide, manganese oxide and mixtures thereof. 5. The glass-fiber composition of any of claims 1 to 4, characterized in that the composition contains 0.1 to 2 percent by weight, in particular 0.3 to 1.5 percent by weight, phosphorus oxide. 6. The glass-fiber composition of any of claims 1 to 5, characterized in that the composition contains less than 2 percent by weight magnesium oxide.

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