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Publication numberUSRE35557 E
Publication typeGrant
Application numberUS 08/432,000
Publication dateJul 8, 1997
Filing dateMay 1, 1995
Priority dateJun 1, 1990
Fee statusPaid
Publication number08432000, 432000, US RE35557 E, US RE35557E, US-E-RE35557, USRE35557 E, USRE35557E
InventorsSylvie Thelohan, Alain DeMeringo, Hans Furtak, Wolfgang Holstein
Original AssigneeIsover-Saint Gobain
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Biodegradable insulation material, mixed oxides
US RE35557 E
Abstract
The present invention relates to mineral fiber compositions useful for forming fibers which are readily degraded in a physiological medium such as that found within the human body. Advantageous compositions formed according to the present invention comprise the following components in the proportions by weight set forth below:
______________________________________
SiO2 37 to 58 wt. %;Al2 O3 4 to 14 wt. %;CaO 7 to 40 wt. %;MgO 4 to 16 wt. %;P2 O5 1 to 10 wt. %;Fe2 O3 up to about to 15 wt. %:______________________________________
wherein the amount of CaO+MgO+Fe2 O3 is greater than 25% and the total amount of Na2 O+K2 O is less than 7%. The total iron contained within the composition is expressed in the form of ferric oxide (Fe2 O3).
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Claims(9)
We claim:
1. A mineral fiber composition decomposable in a physiological medium, said composition consisting essentially of:
______________________________________SiO2         37 to 58 wt. %;Al2 O3  4 to 11.5 .[.14.]. wt. %;CaO               7 to 40 wt. %;MgO               4 to 16 wt. %;P2 O5   1 to 7 .[.10.]. wt. %;Fe2 O3  0.1 to 15 wt. %;Na2 O + K2 O             up to about 7 wt. %; andImpurities        up to about 3 wt. %,______________________________________
wherein the amount of CaO+MgO+Fe2 O3 is greater than 25 wt. % of the composition.
2. The composition of claim 1, wherein the amount of SiO2 +Al2 O3 is greater than about 50 wt % of said composition.
3. The composition of claim 1 wherein the amount of CaO+MgO less than about 40 wt % of said composition.
4. A mineral fiber composition decomposable in a physiological medium, said composition consisting essentially of:
______________________________________SiO2         45 to 57 wt. %;Al2 O3  3 to 6 wt. %.CaO               20 to 30 wt. %MgO               6 to 16 wt. %;Fe2 O3  1 to 7 wt. %;P2 O5   0.1 to 4 wt. %;Na2 O + K2 O             0.1 to 5 wt. %;Impurities        up to about 3 wt. %______________________________________
wherein the amount of CaO+MgO+Fe2 O3 is greater than about 25 wt % of said composition.
5. A mineral fiber composition decomposable in a physiological medium, said composition consisting essentially of:
______________________________________SiO2         40 to 50 wt. %;Al2 O3  7 to 11.5 .[.13.]. wt. %;CaO               20 to 30 wt. %;MgO               6 to 16 wt. %;P2 O5   3 to 7 .[.9.]. wt. %;Fe2 O3  up to about 4 wt. %;Na2 O + K2 O             0.1 to 5 wt. %; andImpurities        up to about 3 wt. %;______________________________________
wherein the amount of CaO+MgO+Fe2 O3 is greater than 25 wt. % of the composition.
6. Mineral fibers comprising the mineral fiber compositions set forth in any one of claims 1 to 5.
7. An insulating material comprising the mineral fibers of claim 6. .Iadd.
8. A mineral fiber composition decomposable in a physiological medium, said composition consisting essentially of:
SiO2 in an amount of about 45 to 57 wt. %
Al2 O3 in an amount of about 4 to 6 wt. %
CaO in an amount of about 7 to 40 wt. %
MgO in an amount of about 4 to 9.1 wt. %
P2 O5 in an amount of about 1 to 7 wt. %
Fe2 O3 in an amount of about 2.1 to 15 wt. %, and
Na2 O+K2 O in an amount of about 0.1 to 5 wt. %; wherein the composition contains impurity elements in an amount of less than about 3 wt. % and the amount of CaO+MgO+Fe2 O3 is greater than 25 wt. % of the composition.Iaddend.. .Iadd.
9. A mineral fiber composition decomposable in a physiological medium, said composition consisting essentially of about 49.7 wt. % SiO2, about 2.1 wt. % Fe2 O3, about 4.5 wt. % Al2 O3, about 29.5 wt. % CaO, about 7.4 wt. % MgO, about 1.4 wt. % Na2 O, about 1.3 wt. % K2 O, about 3 wt. % P2 O5 and impurities in an amount of about 1.1 wt. %, wherein the weight ratio of P2 O5 to (Al2 O3 and Fe2 O3) is about 0.45..Iaddend.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS

Continuation of Ser. No. 708,661, May 31, 1991, abandoned .[., which is a continuation-in-part of Ser. No. 565,282, Aug. 9, 1990, U.S. Pat. No. 5,108,957.]..

FIELD OF THE INVENTION

The present invention relates to mineral fibers which, by virtue of their composition, are readily decomposable upon contact with a physiological medium.

BACKGROUND OF THE INVENTION

Buildings are frequently insulated with respect to heat and sound by products incorporating mineral fibers, such as rock or slag fibers. The particular arrangement of the premises to be insulated often requires the personnel responsible for fitting these products to cut and/or shape them at the job site, this operation, however, typically causes breakage of the fibers and the possible dispersion of some of these fibers and/or fiber fragments into the atmosphere.

In a like manner mineral fibers are also used in industry to produce, e.g., geometrically shaped panels and tubular products for various applications. In addition such fibers are also commonly used in industry to form, e.g., mats sewn over cardboard or metal grills or netting to form pads or alternately to form such pads by filling in bulk form. In many of these applications the finished product must be cut and/or shaped prior to its final installation.

It follows, therefore that at times there is a danger of accidental inhalation of fibers or fiber fragments by those who come into contact with them. Although the inhalation of these fibers and/or fragments has not been demonstrated to be harmful, the need is felt to reassure those working with these products by offering them a demonstrably safe product.

SUMMARY OF THE INVENTION

An object of the present invention is to provide mineral fibers having a composition which decomposes rapidly upon contact with a physiological medium. By a "physiological medium", applicants make a medium such as that typically found within a human body.

A further object of the present invention is to provide composition which may be formed into decomposable fibers of the type described above by the use of so-called "outer" centrifugation techniques.

Outer centrifugation techniques, which are well known in the art, are typically used to form fibers from glasses obtained by melting raw materials such as blast furnace slag or basalts. Some of these techniques, also referred to as free centrifuging techniques, involve pouring a thin stream of molten glass onto the peripheral strip of a centrifuging wheel rotating at high speed about a shaft perpendicular to the direction of the thin glass stream. Under the effect of centrifugal force, some of the glass is converted into fibers, with the remainder of the glass being conveyed to a second wheel where the same procedure is repeated. In this manner, therefore, three or four wheels may be interposed along the path of the molten glass. Techniques such as those described above are particularly useful in forming the mineral fibers of the present invention.

The objects of the present invention are achieved by modifying known glass compositions typically used in the free centrifuging techniques described above. Based upon compositions of this type, essentially comprising silica, alumina and alkaline earth oxides, it has been discovered that the addition of phosphorus pentoxide results in the formation of mineral fibers which decompose rapidly in a physiological medium.

It has further been found that mineral fibers formed from the compositions of the present invention do not suffer any substantial diminution of their properties in comparison to those of prior art products, i.e., those which are only slightly or not at all decomposable in a physiological medium. Thus, the compositions of the invention can be readily converted into fibers using conventional centrifuging wheels.

The mineral fibers formed according to the present invention are prepared from compositions comprising the following components (in weight percent):

______________________________________  SiO2    37 to 58%  Al2 O3                4 to 14%  CaO           7 to 40%  MgO           4 to 16%  P2 O5                1 to 10%  Fe2 O3               up to 15%______________________________________

wherein the amount of CaO+MgO+Fe2 O3 is greater than 25% by weight of the total composition, and the total amount of Na2 O and K2 O is less than about 7 wt. %. The total iron contained in the compositions of the invention is expressed in the form of ferric oxide (i.e., Fe2 O3).

The compositions defined above may, if desired, be prepared from substantially pure constituents. Generally, however, they are obtained by melting a mixture of vitrifiable raw materials, possibly additionally containing other metal oxides such as, for example, titanium oxide and manganese oxide. These additional oxides are considered as impurities within the scope of the invention. The total content of these impurities should be maintained at less than or equal to about 3 weight percent of the total composition.

To permit the formation of mineral fibers from the compositions of the invention with the use of outer centrifuging techniques, the compositions of the invention must have a suitable, viscosity at a relatively low temperature. The viscosity of these materials depends to a great extent on the total amount of SiO2 and Al2 O3 in the subject compositions. Within the scope of the invention, the amount of these oxides is generally equal to or greater than about 50 weight percent of the total composition.

In addition, the ability to produce fibers from the compositions of the invention is inversely proportional to the ability of the material to develop crystals in its mass. This phenomenon, known as devitrification, is characterized by several temperatures: that at which the rate of crystal growth is at its maximum and that at which this rate of growth is zero, i.e., the liquidus temperature. Generally, devitrification may be increased or decreased by adjusting the total amount of alkaline earth oxides in the composition. Within the scope of the invention, the amount of such alkaline earth oxides should be maintained at less than about 40 weight percent of the total composition.

Moreover, in order to ensure that the fibers formed according to the invention are sufficiently heat resistant, it is desirable for the amount of CaO+MgO+-Fe2 O3 in the compositions to be greater than about 25 weight percent of the composition.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first preferred range of components for mineral fiber formed according to the present invention is set forth below in the following proportions by weight:

______________________________________SiO2             45 to 57%Al2 O3      3 to 6%CaO                   20 to 30%MgO                   6 to 16%Fe2 O3      0.1 to 4%P2 O5       1 to 7%Na2 O + K2 O                 0.1 to 5%Impurities            ≦3%______________________________________

A second embodiment of the present invention comprises the following components in the following weight proportions:

______________________________________SiO2             39 to 50%Al2 O3      7 to 13%CaO                   20 to 30%MgO                   6 to 16%Fe2 O3      0.1 to 4%P2 O5       3 to 9%Na2 O + K2 O                 0.1 to 5%Impurities            ≦3%______________________________________

The advantages of the mineral fiber compositions of the present invention are set forth in the following description, illustrated by some non-limiting examples.

EXAMPLES

The measurements of the degree of decomposition undergone by the fibers of the present invention in the physiological medium were performed on fibers having a substantially constant diameter of approximately 10 μm.

The fibers were immersed in a solution which simulated an extracellular fluid having the following composition (expressed in g/l):

______________________________________MgCl2.6H2 O              0.212NaCl               6.415Na2 HPO4 0.148Na2 SO4.2H2 O              0.179CaCl2.4H2 O              0.318NaHCO3        2.703(Na2 tartrate).2H2 O              0.180(Na3 citrate).5, 5H2 O              0.186Na lactate         0.175Na pyruvate        0.172Glycine            0.118______________________________________

The test conditions selected for determining the degree of decomposition of the mineral fibers in the above-described solution were as follows: 200 mg of fibers were placed between two perforated discs separated by a circular ring. These two discs, each 4.3 cm in diameter, were covered with a polycarbonate filter. This assembly formed a measuring cell through which the physiological solution was circulated. The flow rate of the solution was regulated by a peristaltic pump. The flow rate of the solution was 40 ml per day, with the duration of the test being 20 days. The cell and the flask containing the physiological solution was maintained at a substantially constant temperature of 37 C. After passing through the cell, the physiological solution was collected in bottles to permit subsequent analysis. The amount of dissolved silica within the solution was thereafter measured by analysis such that the weight of dissolved silica in relation to the weight of silica initially present in the fiber provided a percentage result. This percentage is therefore a good indicator of the capacity of the fiber tested to decompose in a physiological medium.

The compositions tested and the results obtained are presented in Tables 1 and 2 set forth below. Table 1 sets forth several mineral fiber compositions according to the invention, as well as two prior art compositions used as a reference (i.e., example no. 1 and no. 4). As illustrated in Table 2, therefore, the presence of phosphorous pentoxide in compositions formed according to the present invention has thus been demonstrated to have the effect of increasing the rate of decomposition of fibers formed from these compositions when such fibers are placed in a physiological medium.

A comparison between example nos. 1 and 3, on the one hand, and example nos. 4 and no. 6, on the other, shows that the effect of reducing the alumina and replacing this amount by silica causes a considerable increase in the degree of decomposition of the fibers tested.

A comparison between example nos. 2 and 3, and between example nos. 5 and 6, illustrates that in examples where the degree of decomposition is considerable, the substitution of silica by phosphorus pentoxide results in a substantial increase in the degree of decomposition on the fibers tested.

The influence of phosphorus pentoxide on the degree of decomposition of the fibers is still quite considerable in compositions having a high alumina content, as shown by the results obtained with example nos. 4 and 7.

The phosphorus containing compound is added to the vitrifiable mixture as, for example, disodic phosphate or calcium phosphate. When the amount of phosphate introduced into the vitrifiable mixture is relatively large, it may sometimes be difficult to melt the mixture. It is for this reason that the phosphorus pentoxide content of the compositions of the invention is maintained at an amount less than or equal to about 10 weight percent of the total composition.

Preferably, the compositions according to the invention comprise less than about 7 weight percent of alkaline oxides. Such compositions have viscosity and devitrification properties suitable to permit the formation of mineral fibers from these compositions with the use of outer centrifuging techniques of the type described above. In addition, as shown, the resultant fibers have a high rate of decomposition in a physiological medium. The mineral fibers of the invention listed in table no. 1 are all resistant to temperatures of up to about 700 C. It was found that sample blocks of these fibers (100 kg/m3) heated into an oven during 30 minutes sag less than 10% at 700 C.

The compositions of the invention may be converted into fibers by known "outer" centrifuging devices, such as those described in U.S. Pat. Nos. 2,663,051 and 4,661,134 or French Patent Publication No. 2,609,708, for example, The disclosure of each of these references in incorporated herein by reference.

The fibers obtained in this manner permit the formation of excellent quality fibrous products suitable for numerous applications. Thus, for example, the fibers of the present invention may advantageously be formed into geometrically shaped panels, stiffened by a polymerized bonding material, or into tubular products intended, e,g., for duct insulation. Fibers produced according to the invention may also be used to form mats sewn over cardboard or metal grills or netting in the form of pads, or even in bulk form, i.e., by filling.

              TABLE NO.1______________________________________Compositions in weight percentages Ex.    Ex.     Ex.  Ex.  Ex.   Ex.  Ex.  Ex.Consti- No.    No.     No.  No.  No.   No.  No.  No.tuents 1      2       3    4    5     6    7    8______________________________________SiO2 47.1   49.9    56.4 45.7 49.7  52.7 39.7 44.9Fe2 O3 12.9   12.9    12.9 2.1  2.1   2.1  2.1  10Al2 O3 13.8   4.5     4.5  11.5 4.5   4.5  11.5 4.5CaO   10.3   10.3    10.3 29.5 29.5  29.5 29.5 29.5Mgo   9.1    9.1     9.1  7.4  7.4   7.4  7.4  7.4Na2 O 2.7    2.7     2.7  1.4  1.4   1.4  1.4  1.4K2 O 1.2    1.2     1.2  1.3  1.3   1.3  1.3  1.3P2 O5 0.3    6.5     0.3  0.1  3     0.2  6    3Impur- 2.6    2.9     2.6  1.0  1.1   0.9  1.1  0.7ities______________________________________

              TABLE No.2______________________________________Chemical Resistance in Physiological MediumAmount of dissolved SiO2 (in percent)dura-tion Ex.     Ex.    Ex.   Ex.  Ex.   Ex.  Ex.   Ex.of   No.     No.    No.   No.  No.   No.  No.   No.test 1       2      3     4    5     6    7     8______________________________________20   0.7     5.1    2.5   0.9  11.4  5.2  2.6   53days______________________________________

While it is apparent that the invention herein disclosed is well calculated to fulfill the objectives stated above, it will be appreciated that numerous modifications and embodiments may be devised by those skilled in the art. It is intended that the appended claims cover al such modifications and embodiments as fall within the true spirit and scope of the present invention.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2663051 *Jan 24, 1951Dec 22, 1953Johns ManvilleMethod and apparatus for fiberizing mineral materials
US3013888 *Nov 6, 1959Dec 19, 1961Saint GobainGlass composition
US3328142 *Jul 26, 1960Jun 27, 1967Saint GobainFormation of glass mats
US3513002 *Apr 29, 1966May 19, 1970Johns ManvilleChemical resistant glass composition for fiberization
US3853569 *Jul 1, 1970Dec 10, 1974Saint GobainSilicate glass fiber compositions
US4312952 *Apr 11, 1980Jan 26, 1982Oy Partek AbFor glass wool insulation
US4381347 *Jul 7, 1981Apr 26, 1983Oy Partek AbFibre glass composition
US4605415 *Dec 2, 1983Aug 12, 1986Region Wallonne, Representee Par L'executif Regional WallonBioreactive materials
US4615988 *Sep 19, 1984Oct 7, 1986Isover Saint-GobainGlass fibers and a composition for manufacturing the same
US4756732 *Apr 7, 1986Jul 12, 1988Isover Saint-GobainIntroducing molten glass comprising oxides of silicon, iron, aluminum, calcium, sodium, potassium into spinner, rotating spinner, attenuating glass streams into fibers
US4756785 *Nov 24, 1986Jul 12, 1988Bayer AktiengesellschaftReacting polyisocyanate, polyol, organic compound containing ketoxime group
US4759974 *Jun 20, 1986Jul 26, 1988Isover Saint-GobainGlass fiberization
US5108957 *Aug 9, 1990Apr 28, 1992Isover Saint-GobainGlass fibers decomposable in a physiological medium
EP0009418A2 *Sep 26, 1979Apr 2, 1980Oy Partek AbGlass composition for the production of fibres
EP0247817A1 *May 26, 1987Dec 2, 1987Pfizer Inc.Alkali-resistant glass fiber
EP0412878B1 *Aug 1, 1990Mar 16, 1994Isover Saint-GobainGlass fibres degradable in physiological medium
GB2080281A * Title not available
SU525623A1 * Title not available
SU1211233A1 * Title not available
WO1987005007A1 *Feb 17, 1987Aug 27, 1987Manville CorpINORGANIC FIBER COMPOSITION CONSISTING ESSENTIALLY OF Al2O3, MgO, CaO AND SiO2
WO1989012032A2 *May 25, 1989Dec 14, 1989Manville Sales CorpProcess for decomposing an inorganic fiber
WO1992009536A1 *Nov 22, 1991Jun 11, 1992Paroc Oy AbMineral fibre composition
Non-Patent Citations
Reference
1Chemical Abstract, vol. 108, No. 8 (Feb. 1988) #612226y.
2 *Chemical Abstract, vol. 108, No. 8 (Feb. 1988) 612226y.
3Chemical Abstract, vol. 81, No. 26 (Dec. 1974) #175133v.
4 *Chemical Abstract, vol. 81, No. 26 (Dec. 1974) 175133v.
5Chemical Abstract, vol. 84, No. 12 (Mar. 22, 1976) #78592y.
6 *Chemical Abstract, vol. 84, No. 12 (Mar. 22, 1976) 78592y.
7Chemical Abstract, vol. 84, No. 12 (Mar. 22, 1983) #78607g.
8 *Chemical Abstract, vol. 84, No. 12 (Mar. 22, 1983) 78607g.
9Chemical Abstract, vol. 92, No. 8 (Jun. 1980) #202476v.
10 *Chemical Abstract, vol. 92, No. 8 (Jun. 1980) 202476v.
11Chemical Abstract, vol. 98, No. 8 (Feb. 21, 1983) #58810d.
12 *Chemical Abstract, vol. 98, No. 8 (Feb. 21, 1983) 58810d.
13L.L. Hench et al., "Biomaterials -An Interfacial Approach", Academic Press, 1982, pp. 68-71, 134-143. no month.
14 *L.L. Hench et al., Biomaterials An Interfacial Approach , Academic Press, 1982, pp. 68 71, 134 143. no month.
15McVay, Materials Research Symposia Proceedings, "Stability of Radioactive Waste Glasses Assessed from Hydration Thermodynamics", vol. 26, 1983, pp. 755-761, Nov.
16 *McVay, Materials Research Symposia Proceedings, Stability of Radioactive Waste Glasses Assessed from Hydration Thermodynamics , vol. 26, 1983, pp. 755 761, Nov.
17 *N.K. Mitra et al., Indian Ceramics, vol. 13, No. 4, 1968, pp. 97 102, Jul.
18N.K. Mitra et al., Indian Ceramics, vol. 13, No. 4, 1968, pp. 97-102, Jul.
19Silikattechnik (1960) No. 2 -"Erfahrungsaustausch" by Martin Hubscher, pp. 88-90. no month.
20 *Silikattechnik (1960) No. 2 Erfahrungsaustausch by Martin Hubscher, pp. 88 90. no month.
21 *Ullmanns Encyklopadie der Technishen Chemie, 1976 pp. 359 365. no month.
22Ullmanns Encyklopadie der Technishen Chemie, 1976 pp. 359-365. no month.
23 *Z.M. Syritskaya, Steklo 1 Keremlka, vol. 15, 1958 No. 6 no month.
24Z.M. Syritskaya, Steklo 1-Keremlka, vol. 15, 1958 No. 6 no month.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US6861381Aug 24, 2000Mar 1, 2005The Morgan Crucible Company PlcHigh temperature resistant saline soluble fibres
US6987076Sep 14, 1999Jan 17, 2006The Morgan Crucible Company PlcBonded fibrous materials
US7259118Apr 28, 2004Aug 21, 2007The Morgan Crucible Company PlcInsulation
US7651965Nov 20, 2008Jan 26, 2010The Morgan Crucible Company PlcSaline soluble inorganic fibres
US7803731 *Aug 15, 2007Sep 28, 2010Johns ManvilleFire resistant glass fiber
US7887917Jun 30, 2006Feb 15, 2011Unifrax I Llccontaining calcium oxide and alumina as the major fiber components; provided with a coating containing phosphoric acid, alkali metal or alkaline metal phosphates; high temperature resistance thermal, electrical, or acoustical insulating material
US7989375Jul 3, 2006Aug 2, 2011Nippon Electric Glass Co., Ltd.Glass fiber composition, glass fiber, and glass fiber containing composition material
US8551897Jan 24, 2011Oct 8, 2013Unifrax I LlcInorganic fiber
US8652980Nov 16, 2011Feb 18, 2014Unifax I LLCInorganic fiber
Classifications
U.S. Classification501/11, 501/70, 501/63, 501/35, 501/36, 501/69
International ClassificationC03C3/097, C03C13/06, C03C13/00
Cooperative ClassificationC03C3/097, C03C13/06, C03C2213/02, C03C13/00
European ClassificationC03C13/00, C03C3/097, C03C13/06
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