Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C1/00—Ingredients generally applicable to manufacture of glasses, glazes, or vitreous enamels
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C13/00—Fibre or filament compositions
  • C03C13/001—Alkali-resistant fibres
  • C03C13/002—Alkali-resistant fibres containing zirconium
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
  • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
  • C03C3/087—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal containing calcium oxide, e.g. common sheet or container glass
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
  • C03C3/089—Glass compositions containing silica with 40% to 90% silica, by weight containing boron
  • C03C3/091—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium
  • C03C3/093—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium containing zinc or zirconium

Definitions

• the invention herein relates to alkaline- resistant glasses. While it pertains to glass bodies generally, it has particular pertinence to glasses which are fiberizable.
• the natural mineral zeolites are a group of hydrous alkali metal and/or alkaline earth metal aluminosilicates which have an open three-dimensional crystalline framework. While a large number of individual mineral zeolites are known and have been described in the literature, eleven (11) minerals make up the major group of mineral zeolites: analcime, chabazite, clinoptilolite, erionite, ferrierite, heulandite, laumontite, mordenite, natrolite, phillipsite and wairakite. The chemical and physical properties of these major mineral zeolites, as well as the properties of many of the minor mineral zeolites, are described extensively in Lefond (ed.).
• Alkaline resistance is provided in some glasses by the inclusion of zirconia and/or titania, such as in AR glasses of Pilkington. Although these materials enhance the alkaline resistance of glass bodies, these are refractory materials which increase the melting point of such glasses. Also, zirconia and titania tend to add cost to the glass inasmuch as these are much more expensive materials than silica, soda, calcia and the usual components of soda lime silica glasses. Although calcia tends to lower the melting point of the glass composition, a general admonition exists in the glass technology against using calcium oxide in quantities greater than about fifteen percent (15%) by weight of the glass body.
• Objects of the Invention It is an object of the invention to produce fiberizable alkaline-resistant glasses. Another object of the invention is to modify a silica source, e.g., naturally occurring zeolite materials with readily available aluminum and alkaline earth metal compounds, to achieve an optimal ratio of certain components of the resulting glass composition. A further object of the invention is to optimize alkaline resistance and fiberizability by controlling the molar ratio of certain oxides within the glass composition.
• a silica source e.g., naturally occurring zeolite materials with readily available aluminum and alkaline earth metal compounds
• the invention herein comprises glass compositions which have outstanding resistance to alkaline environments and, in particular, to glass compositions which are readily fiberizable. Such glass compositions are characterized by a high alkaline earth metal oxide content, a relatively low silica content and a significant alumina content.
• these glass compositions are derived from a silica source, e.g., a naturally occurring zeolite, at least one alumina source, preferably an alumina source which is separate from the silica source, and at least one alkaline earth metal oxide source, especially a calcia source, to yield a glass composition predominately of silica, alumina and alkaline earth oxide, especially calcia, wherein the molar ratio of silica plus alumina to calcia plus magnesia falls within the range of about 1.4:1 to about 2.0:1 for certain calcia contents and from about 1.6 to 2.3 for lower calcia contents.
• a silica source e.g., a naturally occurring zeolite
• at least one alumina source preferably an alumina source which is separate from the silica source
• at least one alkaline earth metal oxide source especially a calcia source
• Soda, potassia, and boria as well as zirconia and other glass-forming and glass-modifying components may be present in minor amounts.
• glass bodies, particularly fibers, formed from the aforesaid glass composition are also included within the scope of the present invention.
• FIG. 1 is a graph of alkaline resistance and fiberizability plotted against the molar ratio of silica plus alumina to calcia plus magnesia for various glass compositions.
• the present invention relates to the preparation of alkaline resistant glasses having excellent viscosity and devitrification characteristics especially suitable for fiberization, particularly fiberization by drawing said glasses through dies.
• the preparation of such glasses involves the combining of glass-forming materials including a silica source, especially silceous materials containing sodium, potassium and/or aluminum components, so that the glasses which preferably contain minor portions of soda and/or potassia have a molar ratio of silica plus alumina to calcia plus magnesia of about 1.4:1 to about 2.0:1 for glasses having in excess of 24% by weight calcia and preferably from about 1.5:1 to about 1.9:1 and especially from about 1.6:1 to about 1.8:1.
• said molar ratio is generally from about 1.6 to about 2.3, preferably from about 1.8 to about 2.3, and especially from about 2.0 to about 2.3.
• Glasses of this invention may involve preparation from silica sources having one or more of a plurality of other materials such as aluminum, calcium, magnesium, sodium and potassium in various quantities.
• a glass-forming mixture comprising at least one silica source, frequently one containing a minor quantity of alumina, e.g., less than about 5% by weight, at least one separate alumina source, and at least one calcia source such that the glass formed from said mixture comprises about 45% by weight to about 60% by weight of silica, about 2% by weight to about 20% by weight of alumina, about 24% by weight to about 30% by weight of calcia, and about 0% by weight to about 24% by weight of magnesia, and less than 3% by weight of zirconia, provided that the molar ratio of silica plus alumina to calcia plus magnesia in said glass is in the range of about 1.4 to about 2, preferably from about 1.5 to about 1.9 and especially between about 1.6 and about 1.8.
• molar ratios are particularly applicable to glasses containing minor quantities, e.g., up to 5% by weight of soda and/or potassia and more particularly to glasses containing minor quantities of boria, e.g., up to about 5% by weight, and especially to glasses having a combined soda, potassia and boria content of from about 3% to about 10% by weight.
• the molar ratio is most effective in providing optimum properties, such as fiberizability and alkaline resistance when the CaO + MgO content is from about 25% to about 35% by weight.
• the magnesia content is preferably less than about 10% by weight and especially below about 5% by weight.
• a glass-forming mixture comprising at least one silica source, at least one alumina source, and at least one calcia source, such that the glass formed from said mixture comprises about 45% by weight to about 60% by weight of silica, about 2% by weight to about 20% by weight of alumina, about 18% by weight to about 22% by weight of calcia, about 0% by weight to about 30% by weight of magnesia, and less than 3% by weight of zirconia, provided that the molar ratio of silica plus alumina to calcia plus magnesia in said glass is in the range of about 1.6 to about 2.3, preferably about 1.8 to about 1.3, and especially from about 2.0 to about 2.3
• Boron and zirconium components are absent from naturally occurring mineral zeolites in quantities which have any effect upon the processing characteristics of batch materials or properties of a finished glass article. It is frequently desirable to include boron and/or zirconium components in the glass batch in minor quantities such that the finished glass article has less than about 6% by weight B 2 O 3 and less than about 3% by weight ZrO 2 .
• the inclusion of boron compounds in the glass batches of this invention tends to improve fiberizability and reduce melting temperature of the resulting glass while the presence of zirconia in the glass tends to improve alkaline resistance of a glass already possessing outstanding alkaline resistance.
• the invention particularly relates to glasses formed from naturally occurring zeolites and especially from glasses wherein such zeolites provided a predominance of the glass-forming components. It is significant, as described hereinafter, that such glasses may be easily and inexpensively formed by melting the glass-forming mixture noted above.
• zeolite materials especially those of high alumina content
• glasses especially as fibers, under appropriate conditions.
• the zeolites as a glass-forming material, have many advantages.
• Naturally occurring zeolites have already undergone reaction and the various elements are intimately mixed and reacted with one another.
• the zeolite materials are particularly useful inasmuch as they have a very low sulfur content.
• very useful glass bodies may be formed by combining various quantities of alumina and, preferably, an alkaline earth metal component such as calcia or calcia and magnesia combinations with a zeolite of the following compositional range:
• Suitable alumina sources for inclusion in the glass-forming mixture of the present invention include alumina, various clays having a high alumina content such as kaolin, montmorillonite and the like, and aluminum compounds such as aluminum chloride, aluminum sulfate and the like.
• Suitable silica sources include zeolite materials, pure silica, and various glass cullets having a high silica content.
• a glass-forming composition may be readily formed by mixing a calcia source, e.g., a finely ground limestone with a silica source, e.g., a finely ground zeolite material, such as the composition identified above, and a finely ground alumina-forming material in proportion to obtain the above-noted glass composition.
• a calcia source e.g., a finely ground limestone
• silica source e.g., a finely ground zeolite material, such as the composition identified above
• the glass material upon cooling, exhibits good physical properties, having strengths and other qualities substantially equivalent to a typical soda-lime silicate glass. If the glass has the composition parameters noted above, resistance to alkaline solutions from about ten-fold to twenty-fold better than a typical soda-lime silicate window glass, as well as improved fiberizability, are achieved.
• zeolite-type glasses containing increased alumina and high calcia and/or magnesia loadings have other advantages as well.
• the addition of alumina-forming materials and calcium and/or magnesium compounds tends to even. out variances in the zeolite composition.
• Zeolites are naturally occurring materials and are not homogenous or uniform in their composition.
• Naturally occurring zeolites contain various quantities of alumina and calcia.
• the alumina content may vary significantly depending upon the mineral type.
• a few mineral zeolites contain alumina in sufficient quantities to form readily fiberizable glasses.
• most zeolite materials contain low amounts of alumina in differing quantities.
• addition of alumina to such zeolites provides a glass-forming composition of substantially uniform composition from batch to batch which has good fiberizability and, through addition of alkaline earth metal components, good alkaline resistance.
• zeolite material Although smaller or larger quantities of zeolite material may be utilized, good results are achieved from a glass-forming composition which has about 35% by weight, or more, of a naturally occurring zeolite. Improved fiberizability is achieved from glass-forming compositions having about 40% or more zeolites unless additional silica, alumina, etc. of the same ratios as exist in the zeolite are included in the batch. Excellent results have been achieved with zeolite compositions of about 50% or more.
• Such naturally occurring zeolites may contain high quantities of alumina, but typically contain up to about 10% by weight.
• alumina-forming materials are added in quantities of about 0.1% by weight to about 20% by weight, and preferably from about 2% to about 15% by weight, calculated as alumina to the zeolite materials to obtain glasses with improved fiberizability.
• alkaline earth metal components are also preferably added to alumina modified zeolite glass-forming compositions. It is, of course, within the scope of the invention to add quantities of silica to achieve uniform batch compositions or to achieve particular silica to alumina ratios. Usually such silica additions are unnecessary but may be made if desired. Additions of soda, potassia and the like may also be made, but since low soda and potassia contents are desired, such additions are usually not practiced.
• the zeolites contain relatively substantial quantities of water, that is, hydrated materials.
• Hydrated crystalline materials generally tend to melt at a lower temperature.
• the melting temperatures of the glasses of this invention come within a range, preferably about 1300oC to about 1500°C, which permits the drawing of glass fibers through platinum dies.
• the glass fibers could also be formed by spinning or other techniques. However, formation of continuous strands is best accomplished by drawing through an orifice in a platinum or platinumrhodium body.
• Fibers of the glass compositions of this invention are particularly useful inasmuch as they may be used to strengthen bodies which are highly alkaline in nature, for example, cement and plaster. Such fibers may also be used to strengthen organic matrices of various types. Remrorcement or cement with such fibers, however, provides a particularly advantageous use inasmuch as asbestos has been frequently used heretofore for that purpose. Because of various health and/or environmental concerns, the use ot asbestos is diminishing. Continuous strands or mats of glass fibers having the glass compositions described herein effectively reinforce concrete bodies.
• Naturally occurring zeolites were finely comminuted, admixed with particulate alumina, calcium carbonate, magnesium carbonate, limestone or dolomite, as indicated, and melted to form glass bodies and fibers.
• the melting was conducted batch-wise in small crucibles at temperatures of about 1350"C to about 1500oC depending upon zeolite composition and quantity ot alumina and alkaline earth metal material added.
• glasses la and Ila exhibit good resistance to alkali attack, but exhibit poor fiberizability and have a limited working temperature range.
• Glasses lb and lIc in contrast, have compositions within the scope of the present invention and have improved fiberizability and working range while maintaining good resistance to alkali attack.
• Glasses Illb and IIIc of Table II have compositions within tne scope of the present invention and exhibit progressively improving fiberizing and working properties. While some diminishment of alkali resistance was experienced with glasses Illb and IIIc, the alkali resistance is still very good.
• Glass-formmg materials were finely comminuted, admixed with particulate additives as identified in the following tables (expressed in percent by weight) and melted to form glass bodies and fibers.
• the melting was conducted batch-wise in small crucibles at temperatures of about 1250oC to about 1500oC depending upon batch composition and quantity of additives.
• the glasses set forth in Table III were prepared from silica, alumina, calcium carbonate, boria and magnesium carbonate. A zeolite material was not present in the batch. These glasses were prepared from traditional glass-forming materials in order to examine the fiber-forming, alkaline resistance and other properties of the resulting glasses.
• Glass IVc has a composition within the scope of the present invention and exhibits very good properties. Its melting point was reasonably low while its alkaline resistance was very good. Fibers were formed without difficulty.
• Glasses Va and Vb exhibited excellent alkaline resistance; however, fiberizability was rated fair and good respectively.
• Glass Vc exhibited an improved working range over Glasses Va and Vb, although the alkaline resistance was lower.
• Glasses VIa through VId exhibited excellent alkaline resistance and melting temperatures. Glasses VId and VIe exhibited substantial fiberizability and working temperature range although their alkaline resistance was less than Glasses VIa through VIc. Glass VIa exhibits an unacceptably reduced working range.
• the glasses identified in Tables I, II, IV and V were prepared from a zeolite having the following composition: SiO 2 82.8 percent by weight
• compositions may occur from batch to batch of the zeolite.
• Very minor quantities of other elements for example boron, manganese, zirconium, titanium, vanadium, antimony, barium, in combined form, may be present in such a naturally occurring zeolite.
• the quantities of such materials generally are individually below about 0.1% by weight and are usually less than 0.01% by weight and frequently present in amounts less than 0.005% by weight.
• Various other materials, especially those having metallic elements, may be found in trace amounts in the zeolite material.
• the alkaline resistant glasses of this invention it is preferred, if starting with a zeolite material, to have such zeolite material present at least about 35% by weight of the glass batch mixture. If the zeolite provides substantially all the silica component for the resulting glass, then quantities of about 40% to about 50% by weight or more of the zeolite may be utilized in the glass batch mixture.
• the glass batch mixture may contain a minor quantity of a boria-forming ingredient, such as borax, colemanite, sassolite, ulexite and the like.
• borosilicate materials or borosilicate or boroaluminosilicate glass cullet may be utilized to provide the boron component in the glass batch.
• the boron-containing component is usually present in the glass batch in quantities of up to about 6% by weight and is typically present in sufficient quantities to provide a boria content in the resultant glass of from about 0.1% to about 6% by weight and preferably from about 1% to about 5% by weight and especially preferred from about 1% to about 4% by weight.
• a plot of fiberizability and alkaline resistance for various glass compositions containing about 24% to about 38% by weight calcium oxide is illustrated in FIG. 1.
• Glass compositions identified by molar ratio of silica plus alumina to calcia plus magnesia are plotted along the abscissa.
• a value of the above-noted molar ratio of less than about 1.4:1 is considered for the purposes of the invention as representing a lower fiberizability limit; i.e. a value of 4 on the fiberizability scale.
• a fiberizability value of at least about 7, at a molar ratio of about 1.5, is preferably present in alkaline resistant glasses while a fiberizability of about 9, at a molar ratio of about 1.6, is especially desirable.
• the presence of sodium and potassium compounds in at least some of the batch materials utilized in the instant invention requires proportioning of the batch materials to provide a glass composition having molar ratios of silica plus alumina to calcia plus magnesia within the ranges set forth herein.
• Glass fibers formed from glasses of this invention have particular utility as a reinforcement material for cementatious bodies, e.g., of cement and concrete.
• Cementatious bodies exhibit enhanced strength when such bodies are reinforced with a minor amount of glass fiber, preferably from about 1% to about 10% by weight, and more preferably about 1.5% to about 7.5% by weight glass fibers of the type described herein.
• the fibers are included in cementatious bodies in sufficient amount to enhance the strength of such bodies.
• the glasses of this invention have excellent resistance to moisture degradation and do not degrade or deteriorate during normal or extended storage periods.
• embodiments of the instant invention have been described as having significant loadings of calcia, it is to be recognized that at least minor substitutions of other alkaline earth metal oxides in lieu of calcia may be made.
• magnesium compounds particularly magnesium carbonate may be substituted for at least some of the calcium carbonate in preparing a batch for melting into an alkaline-resistant glass.
• barium and strontium compounds may be substituted as well as beryllium compounds, many of which are naturally occurring materials found in the same geographic regions as zeolites.
• alkaline earth metal elements are not considered glass formers, which is a term applied to elements having a valence greater than three, e.g. silicon, boron, and phosphorous, which may form three-dimensional networks with their oxides, namely, silica, boric oxide, and phosphorous.
• Alkaline earth metal elements, being divalent, are more tightly bound in a glass than are alkali metal elements.
• Sources of alkaline earth metals to form oxides in the glasses of this invention are as follows:
• Sources of calcium and magnesium carbonates are generally more plentiful and cheaper than sources of barium, strontium or beryllium compounds. Also, beryllium metal is considered toxic, although beryllium oxides bound within a glass body are not hazardous.
• Glasses of this invention preferably having less than about 24% by weight CaO exhibit excellent fiberizability but with somewhat diminished alkaline resistance in comparison to glasses having more calcia.
• the lower calcia content glasses are more useful in alkaline environments than many fiberglass materials having much lower alkaline resistance. Also, certain sizings and coatings upon such fiberglass materials may further enhance the alkaline resistance of the glasses of this invention.
• the zeolite-derived glasses of this invention have good working properties and strength in addition to outstanding alkaline resistance.
• These glasses may be used in any form, e.g. containers, sheets, fibers and the like, and especially for any use in which transparency or colorlessness are not required.
• the glasses may be used as flakes, bubbles (microspheres), fibers and the like to reinforce organic or inorganic matrices, especially cement, plaster and the like.

Landscapes

• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Glass Compositions (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=24213953

Family Applications (1)

Country Status (3)

Families Citing this family (16)

Citations (4)

Family Cites Families (12)

• 1984
  • 1984-11-19 JP JP50443884A patent/JPS61500490A/ja active Pending
  • 1984-11-19 WO PCT/US1984/001904 patent/WO1985002393A1/fr not_active Application Discontinuation
  • 1984-11-19 EP EP19850900313 patent/EP0162917A4/fr not_active Withdrawn

Patent Citations (4)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events