High temperature resistant glass fiber

Related Technical Fields The present invention relates to high temperature resistant glass fibers useful as insulating (insulating or soundproofing) materials, the operating temperature limit of which is at least 1260 ° C. More specifically, the present invention is easily manufactured and has low shrinkage and good mechanical strength when exposed to operating temperature, but is intolerant in physiological liquids. Regarding high temperature glass fiber. Background of the Invention In the insulating materials industry, it has been desirable to use fibers that are not resistant in physiological liquids such as lung fluid in the application of fibers to heat insulation and sound insulation. Candidate substances have been listed, but the operating temperature limits of these substances are not high enough that high temperature resistant fibers, including these resistant glasses and ceramic fibers, could not be applied to various uses. .. In particular, high temperature resistant fibers must exhibit minimal linear shrinkage at the desired exposure temperature in order to provide effective thermal protection against the material being insulated. Many artificial glass fiber materials have been proposed that decompose in physiological media. These fiberglasses generally have a significant amount of alkali metal oxide content, which often results in low operating temperature limits. The Canadian filing patent 2017344 has physiological solubility and requires silica, calcia and Na as essential ingredients.₂Magnesia and K with O as the preferred ingredient₂O and glass fibers made from glass containing boria, alumina, titania, iron oxide and fluorine as optional components are described. International Publication Patent WO 90/02713 describes inorganic fibers that dissolve in physiological saline, and these fibers are silica, alumina, iron oxide, calcia, magnesia, and Na.₂O and K₂Contains a composition containing O. U.S. Pat. No. 5,108,957 states that silica, calcia, and Na are essential ingredients.₂O plus K₂O and boria, as well as alumina, magnesia, fluorine and P as optional components₂O₅A glass composition useful for producing glass fibers that can be decomposed in a physiological medium, including the above, is described. It has also been described that the presence of phosphorus has the effect of increasing the rate of fiber degradation in physiological media. Other literature describing the effect of phosphorus on increasing the biosolubility of inorganic fibers includes International Publication Patent WO 92/09536, which substantially contains silica and calcia, but optionally magnesia and Na.₂O plus K₂Inorganic fibers containing O have been described, in which the presence of phosphorus oxide is stated to reduce the stabilizing effect of aluminum and iron on the glass matrix. These fibers are typically manufactured at a lower temperature than refractory ceramic fibers. We have found that at the melting temperature required for high temperature resistant fibers (1700-2000 ° C), even as low as a few percent, phosphorus oxide can cause severe decomposition and / or corrosion of furnace components. Canadian Application Patent No. 2043699 states that it decomposes in the presence of physiological media, silica, alumina, calcia, magnesia, P.₂O₅, And optionally iron oxide, and Na₂O plus K₂Described for fibers containing O. French patent application 2662687 states that it decomposes in the presence of physiological media, silica, alumina, calcia, magnesia, P.₂O₅, Iron oxide, and Na₂O plus K₂O plus TiO₂Described for fibers containing. U.S. Pat. No. 4,604,097 describes bioabsorbable glass fibers, which generally contain a two-component mixture of calcia and phosphorus pentoxide, calcium fluoride, water, and magnesia, zinc oxide, oxidation. Includes other components such as one or more oxides, such as strontium, sodium oxide, potassium oxide, lithium oxide or aluminum oxide. International Publication Patent WO 92/07801 describes glass fibers that can be absorbed by living organisms, including phosphorus pentoxide and iron oxide. P₂O₅A part of iron oxide may be replaced with silica, and a part of iron oxide may be replaced with alumina. The fiber optionally comprises a divalent cation compound selected from Ca, Zn and / or Mg and an alkali metal cation compound selected from Na, k, and / or Li. U.S. Pat. No. 5,055,428 describes soda lime aluminoboron-silicate glass fiber that dissolves in synthetic lung fluid. Alumina content increases boria, and silica, calcia, magnesia, K₂O and optionally Na₂It decreases with the adjustment of O. Other components may include iron oxide, titania, fluorine, barium oxide and zinc oxide. International Publication Patent WO 87/05007 describes inorganic fibers that are soluble in saline and contain silica, calcia, magnesia and optionally alumina. WO 89/12032 contains silicon that can be extracted into physiological saline and contains silica, calcia, optionally magnesia, alkali metal oxides and one or more aluminas, zirconia, titania, boria, and iron oxides. Including, inorganic fibers are described. Internationally published patent WO 93/15028 is soluble in saline and has the usefulness of crystallizing into diopside when heated at 1000 ° C and / or 800 ° C for 24 hours, silica 59-64% by weight, alumina 0 Contains a composition consisting of -3.5% by weight, 19-23% by weight of calcia, and 14-17% by weight of magnesia, and 60-67% by weight of silica in another usefulness of crystallizing into wollastonite / pseudo-wollastonite. Includes a composition consisting of%, 0-3.5% by weight of alumina, 26-35% by weight of silica, and 4-6% by weight of magnesia. However, the fibers described in the above patents have a limited operating temperature and are therefore applicable to high temperature insulation such as, for example, to the inner surface of a furnace used at temperatures above about 1000 ° C, and metals. Inappropriate for reinforcement and friction applications such as matrix components. Products based on non-durable fibrous chemistry are marketed by Unifrax Corporation (Niagara Falls, New York) under the trade name INSULF RAX, 65% by weight SiO.₂, 31.1 wt% CaO, 3.2 wt% MgO, 0.3 wt% Al₂O₃And 0.3% by weight Fe₂O₃It has a composition consisting of. Other products are sold by Thermal Ceramics (Augusta, Georgia) under the trade name SUPER WOOL, 58.5% by weight SiO.₂, 35.4 wt% CaO, 4.1 wt% MgO, and 0.7 wt% Al₂O₃Consists of. This material has a usage limit of 1000 ° C and melts at approximately 1240 ° C, which is too low a temperature to be used for the purposes of high temperature insulation mentioned above. In international application patent WO 94/15883, Al as an additive component₂O₃, ZrO₂, And TiO₂Including CaO / MgO / SiO₂It is stated that the solubility and fire resistance of the fiber in saline solution have been studied. This document states that as the MgO content increases, saline solubility increases, while ZrO₂And Al₂O₃Is stated to be detrimental to solubility. TiO₂(0.71-0.74mol%) and Al₂O₃The presence of (0.51-0.55 mol%) reduces fiber shrinkage below 3.5% at 1260 ° C. This document further describes SiO₂Describes fibers that are too high in content to form or are difficult or impossible to form, 70.04, 73.28, and 78.07% SiO₂Is given as an example in which a sample containing the above cannot be fibrousized. In addition to the heat resistance expressed by shrinkage, which is important for fibers used as insulators, mechanically, which allows the fibers to retain structural maintainability and insulating properties during or after exposure to use or working temperatures. It is also necessary to have strength properties. One property of the mechanical integrity of a fiber is its friability after use. The more easily the fiber is crushed (ie, the easier it is crushed or crushed into powder), the less mechanically maintainable the fiber is. The inventors have found that insulating fibers, which generally exhibit both high temperature resistance and non-durability in biological liquids, also exhibit a high degree of post-use crushability. This causes a lack of strength or mechanical maintainability after the fibers are exposed to the operating temperature, making it possible to provide a structure that serves the purpose of insulation. We have found that high temperature resistant, non-durable fibers that exhibit good mechanical integrity after exposure to operating temperature have very small scale or fine crystalline microstructures. Other methods (measurements) of mechanical maintainability of fibers include compressive strength and compressive recovery. However, the refractory glass composition exhibiting the desired durability, shrinkage at temperature and strength properties may not be prone to fibrosis by either spinning or blowing formation of the melt of its constituents. Therefore, an object of the present invention is a high temperature refractory glass which can be easily produced from a melt having a viscosity suitable for blowing or spinning fibers and is non-durable in a biological liquid. To provide fiber. Furthermore, it is an object of the present invention to provide high temperature refractory glass fibers that are non-durable in biological liquids and exhibit good mechanical strength after exposure to operating temperature. Furthermore, it is an object of the present invention to provide high temperature resistant refractory glass fibers that are non-durable in biological liquids but exhibit low post-use crushability. Further, an object of the present invention is to provide high temperature refractory glass fibers that are non-durable in biological liquids and preferably exhibit small scale or fine microstructures after exposure to the initial operating temperature. provide That is. Furthermore, it is an object of the present invention to provide high temperature resistant refractory glass fibers that are non-durable in biological liquids and exhibit high compressive strength and resilience from compression after exposure to operating temperature. Is. Description of the Invention A high temperature resistant, refractory glass fiber that is non-durable in a biological liquid is provided. The fibers are 4 to 150 times more soluble in experimentally produced lung fluid than standard aluminosilicate refractory ceramic fibers, and have a temperature usage limit of at least 1000 ° C to 1260 ° or higher. Shown. At these high temperatures, the fibers of the invention undergo linear shrinkage of less than about 6%, preferably less than 4.5%, most, when left in that temperature for 24 or 168 hours, as described below. It preferably undergoes a linear contraction of less than 3%. The fibers of the present invention retain their mechanical strength after exposure to operating temperature. Contrary to prior art, the fibers of the invention that meet the requirements of fibrogenicity, fire resistance and non-durability are SiO.₂Was found to be a composition containing in the range of 70 to 86% by weight. The present invention provides glass fibers that are low shrinkage, refractory, based on a magnesium silicate system with an operating temperature of at least 1260 ° C, retain mechanical strength after exposure to operating temperature, and. It is non-durable in biological fluids such as lung fluid. In one aspect of the invention, the non-durable refractory glass fiber must consist of about 65-about 86% by weight silica, about 14-about 35% by weight magnesia, and 0-about 11% by weight zirconia product. And optionally contains an effective amount of the viscosity modifier. The viscosity modifier may be selected from alumina, boria and mixtures thereof. The fiber must not contain more than about 1% by weight of calcia impurities and also iron oxide impurities (Fe).₂O₃(Calculated as) must not contain more than 0.4% by weight. It is preferred that the fibers of the present invention are substantially free of alkali metals (more than trace impurities). The presence of iron oxide and calcia should be limited to the extent possible. The present invention provides a method for producing a fire resistant fiber, which has an operating temperature of at least 1260 ° C., retains mechanical integrity after exposure to operating temperature, and is non-durable in biological liquids. The method provides the following steps. Form a melt containing about 65 to about 86% by weight silica, about 14 to about 35% by weight magnesia, 0 to about 11% by weight zirconia, and optionally an effective amount of viscosity modifier as essential ingredients. And the process of producing fibers from the melt. The melt composition used to produce the fibers of the present invention has a viscosity suitable for blow formation and spinning of the fibers, and the crystal structure of the resulting fibers is mechanical after exposure to the operating temperature. It has a viscosity suitable for adjusting to maintain strength.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A shows a viscosity vs. temperature curve for melt chemistry of commercially available spun aluminosilicate fibers. FIG. 1B shows a viscosity vs. temperature curve for the melt chemistry of commercially available blow-formed aluminosilicate fibers. FIG. 2 shows a viscosity vs. temperature curve for the melt chemistry of magnesia-silica-zirconia fibers containing 75% by weight silica. FIG. 3 shows a viscosity vs. temperature curve for the melt chemistry of magnesia-silica-zirconia fibers containing 70% by weight silica. FIG. 4 shows a viscosity vs. temperature curve for the melt chemistry of magnesia-silica-zirconia fibers containing 75% by weight silica and 1% by weight added alumina. FIG. 5 shows a viscosity vs. temperature curve for the melt chemistry of magnesia-silica-zirconia fibers containing 1% by weight of added alumina. FIG. 6 shows the viscosity vs. temperature curve for the melt chemistry of preferred magnesia-silica-zirconia fibers. FIG. 7 shows the viscosity vs. temperature curve for the melt chemistry of preferred magnesia-silica-zirconia fibers. FIG. 8 is a scanning electron micrograph of a ceramic fiber containing aluminum zirconium silicate (AZS) after exposure at 1426 ° C for 24 hours. FIG. 9 is a scanning electron micrograph of a kaolin-containing ceramic fiber exposed at 1260 ° C. for 24 hours. FIG. 10 is a scanning electron micrograph of glass fibers containing titanium calcium silicate after exposure at 1260 ° C. for 24 hours. FIG. 11 is a scanning electron micrograph after exposing the glass fibers of the present invention at 1260 ° C. for 24 hours. FIG. 12 is a scanning electron micrograph of a cross section of the glass fiber of the present invention. FIG. 13 is a scanning electron micrograph of a cross section of a ceramic fiber containing aluminum zirconium silicate (AZS). Detailed Description of the Invention The present invention is useful as a heat insulating or soundproofing material, has an operating temperature limit higher than 1260 ° C, and is non-durable in physiological liquids such as lung fluid, tolerant. Provide flammable glass fiber. Non-durable in physiological fluids means that the fibers dissolve in at least some of them in such fluids (eg, artificially created lung fluid) in in vitro tests. In order for a glass composition for producing a sufficient high temperature textile product to be a practical candidate, the fiber can be produced, is well soluble in a physiological liquid, and is minimal. It must be able to withstand high temperatures with shrinkage and minimal loss of maintainability. In order to isolate substances that meet these criteria, a series of screening tests was performed to isolate fibers exhibiting the desired properties. These tests are for (a) viscosity / fibrosis, (b) durability, (c) shrinkage at each temperature, and (d) crushability, strength and elasticity after use. The term "viscosity" means the force of a glass melt that can resist the flow or shear the stress. The viscosity-temperature relationship is important in determining whether a given glass composition can be fibrous. The optimum viscosity curve has a low viscosity (5-50 poise) at the fibrosis temperature and gradually increases as the temperature decreases. If the melt is not sufficiently viscous at the fibrosis temperature (ie, too dilute), the result is a very high rate of short, thin fibers containing non-fibrous material (shot). .. If the melt is excessively viscous at the fibrosis temperature, the resulting fibers will be very coarse (high diameter) and short. Viscosity is dependent on melt chemistry and is also affected by factors or compounds that act as viscosity modifiers. The inventors have found that in this fiber chemistry system, alumina and boria act as viscosity modifiers, enabling blow formation or spinning of fibers. However, according to the present invention, such viscosity modifiers, by either type or amount, do not adversely affect the solubility, shrinkage resistance or mechanical strength of blown-formed or spun fibers. .. Viscosity-Temperature profile is viscosity that can be measured at elevated temperatures It may be measured by a meter. In addition, suitable viscosity profiles may be estimated by routine experiments measuring the properties (index, diameter, length) of the produced fibers. Durability testing is the rate of mass loss from fibers (ng / cm) under conditions of artificially creating the temperature and chemical environment found in human lungs.² Measure hr). This test exposes approximately 0.1 g of de-shotted fiber to a stream of artificially created lung fluid (SLF) at 0.3 ml / min. All test systems are maintained at 37 ° C, mimicking the temperature of the human body. The test is preferably continued for about 2-4 weeks. After the SLF flowed through the fibers, it was collected and analyzed for glass composition using an inductively coupled plasma spectrum. A "blank" SLF sample is also measured and used to collect the components present within the SLF. Once this data is available, it is possible to calculate the rate of fiber mass loss at the time intervals of this study. Wet-form the fibers into the pad, measure the length and width of the pad (typically 3 x 5 inches (7.6 x 12.7 cm)) with a caliper, place the pad in the furnace, and place. A fiber shrinkage test was performed by providing a temperature gradient and maintaining it for a predetermined time. After heating, the pad was measured again to measure the dimensional changes that occurred. In such tests, the pad was squeezed by mixing 427 g of fiber, 27.2 g of phenolic binder and about 4 gallons (15 L) of water, pouring the mixture into the sheet mold and draining the water from the bottom of the mold. Created. Dry the pad, 3 inches x 5 inches x 1 inch (7.6 cm x 12.7 cm x 2. It was cut into pieces measuring 5 cm). The length and width of this fragment were carefully measured, placed in a furnace and held at a temperature of 1260 ° C for 24 hours, 168 hours or 672 hours. After cooling, the outer dimensions were measured and the "before" and "after" measurements were compared to determine linear shrinkage. If the fibers are available in blanket form, the measurements may be made directly on the blanket without the need to form pads. (Such blanket shrinkage measurements are not the same as, but are related to, pad shrinkage measurements.) After-service friability is the mechanical integrity of the fiber after exposure to high temperatures. Means the ability to hold. This is an important property as the fibers must support their own weight in any application and must be able to withstand the movement of air or gas. Indications of fiber integrity and mechanical strength are obtained by visual and tactile observation and mechanical measurement of these properties of the fiber after exposure to operating temperature. Post-use maintainability of shrink pads is demonstrated by two types of tests: compressive strength and compressive recovery. Each of these tests measures how easily the pad is deformed and the amount of elasticity (or compression recovery) that the pad exhibits after 50% compression. The shrinkage pad made from the fibers of the present invention was heated at 1260 ° C. for 24 hours or 168 hours, and a compression test was performed using an Instron test apparatus. 2.5 inches (6. A cylindrical ram with a diameter of 4 cm) was pushed into the compression pad until the pad was compressed to half its original thickness. At this point the crosshead was stopped and the peak load (psi) obtained during compression was recorded. The crosshead was slowly moved in the opposite direction, the cylindrical ram retracted from the compression pad until the load was zero, and compression recovery was then measured. The distance traveled from the 50% compression point to zero load was recorded and expressed as a percentage of the original pad thickness. This value indicates the amount of elasticity (recoverability) of the fiber pad. In this test criterion, pads with inferior results show low compressive strength, suggesting that they are easily compressed. The weak compression recovery rate also suggests that once deformed, there is little recovery. On the contrary, a pad / fiber composition in which these parameters show very high values is considered to show high mechanical strength and good properties. The ideal fiber has comparable compressive strength within the desired range as compared to standard commercially available aluminosilicate fibers, yet has high compressive recovery or elasticity. When heated to operating temperature, glass fibers, which are generally amorphous when manufactured, undergo crystallization. In part, the size of the crystals obtained affects the mechanical properties of the fiber. Strong elastic fibers show a very small particle size after firing. After firing, weak fibers typically have very large particles. The particle size after use was measured as follows. The fiber sample is calcined at 1260 ° C (typically 24 hours). The calcined sample is then mounted in the epoxy to cure the epoxy. The epoxy mount is then polished to give the fibers a smooth cross section. This polishing mount is then taken with a scanning electron microscope using backscattering or secondary electron imaging mode (either method that gives the best contrast between the crystal phases). Draw a line on the micrograph (usually from corner to corner) and count the number of crystals that intersect this line. Measure line length and convert to micron based on photomicrograph scale To. For example, a 5 cm line drawn on a 1000x micrograph is measured as 5/1000 cm or 50 microns. Divide the length of the line by the number of intersections of the crystal to get the approximate size of the crystal. In some cases, the crystal size is too small or too scattered to make measurements in this way. In such cases, the "typical" crystal size may be estimated from comparison with micron bars on micrographs. The inventors have stated that adding zirconia to magnesium silicate fibers at a level of up to about 11% by weight improves the microstructure after use and reduces the crushability of the resulting non-durable refractory glass fibers. I found it. It has also been found that such addition of zirconia to the fibers results in the formation of very small scale microstructures when the fibers are exposed at 1260 ° C or lower for 24 hours or less. This small scale or fine microstructure provides good mechanical fiber integrity after exposure to operating temperature. This microstructure may be exposed to the operating temperature for extended periods of time to make it slightly coarser, but these fibers are compared to other non-durable, heat-resistant fibers even after such extended exposure. And retains the improved mechanical properties. The mechanism by which smaller particle sizes improve fiber strength is the ability to create fibers with less irregularity (unevenness). This is because small particle fibers have a smoother surface than coarse particle fibers. Surface flaws serve to create pressure, giving the fibers a point where they may be easily destroyed. Zirconia is known to reduce the glass solubility in SLF, but in the fibers of the present invention this effect is small enough and the resulting fibers show the desired solubility in SLF. The combination of non-durability, ie, solubility in SLF and mechanical maintainability after exposure to an operating temperature of 1260 ° C, has not been shown using fibers described or used by others in the industry. .. The present invention crystallizes the fine structure of fibers in devitrification, i.e. heating to operating temperature, into melt products.₂Is adjusted by adding. Analysis of the durability of the above fibers in pseudopulmonary fluid shows that these fibers are aluminosilicate (about 50/50% by weight) and alumino-zirconia-silicate or AZS (about 30/16/54% by weight). It shows that the fire resistance is clearly lower than that of normal fire resistance ceramic fibers. The non-durable refractory glass fiber of the present invention is produced by a method for producing standard glass and ceramic fiber. Silica, suitable magnesia sources (eg magnesite, forasterite, magnesia, magnesite, calcined magnesite, magnesium zirconate, pericrace, steatite), and suitable zirconia sources (eg badele stone, magnesium zirconate, zircon or zirconia) Raw materials such as are extruded from the bottle into the furnace at a selected ratio, melted, and sprayed using a fibrosis nozzle, or spun in batch or continuous mode. In the presence of the viscosity modifier, the viscosity of the melt may be optionally adjusted to be sufficient to provide the fibrosis required for the intended application. The viscosity modifier may be present in the raw material that supplies the main component of the melt, or at least a part of it may be added separately. The desired particle size of the raw material is determined by the heating conditions in the furnace, such as the size of the furnace (SEF), injection rate, melting temperature, residence time in the furnace. According to one embodiment of the invention, the refractory glass fiber is tolerant to operating temperatures up to at least 1260 ° C and has a linear shrinkage of about 6%, more preferably less than about 4.5%. Shows crushability after small use, and is non-durable in physiological fluids such as lung fluid. Most preferably, the linear shrinkage of the fibers is less than about 3%. The non-durable refractory glass fiber of the present invention contains about 65 to about 86% by weight of silica, about 14 to about 35% by weight of magnesia, and 0 to about 11% by weight of zirconia as essential components, and can be used in an arbitrarily effective amount. Contains a viscosity improver. The fiber must not contain more than about 1% by weight of Calcia impurities, and more than about 0.4% by weight of iron oxide impurities (Fe).₂O₃Do not include (calculated as). The viscosity modifier may be selected from alumina, boria and mixtures thereof. Other components that affect the viscosity of the melt or so that when added to the melt, the properties or shape of the viscosity / temperature curve of the melt are similar to those of the melt, which is easily fibrous, as described below. The compound may be used as a viscosity modifier. Example 1-2 The following compositions were further tested to evaluate the effect of zirconia on the properties of the magnesium silicate composition. Samples with the weight% composition defined below were heated at 1260 ° C. for 24 hours.<img file="JP3676818B2_D0001.tif" />These samples were tested and found to have good microstructures that provide the required good post-use mechanical strength. Comparative example ASiO₂71.5% by weight, CaO 24.5% by weight, Al₂O₃3.2% by weight and TiO₂Fibers containing 0.1% by weight of the nominal composition were tested and found to have the desired durability and shrinkage. However, this fiber decomposed when heated rapidly. We analyzed that the decomposition of this sample was due to the deterioration of the crystal nuclei in the fibers and / or due to the inclusion of excess alumina impurities. Comparative example BSiO₂Contains 75.3% by weight and 21.0% by weight of CaO, 1.5% by weight of TiO₂Fibers containing the composition added as a nucleating agent were made, which had the desired durability and shrinkage, and were also durable against rapid heating. However, this material showed crushability after excessive use, and showed weak elasticity and fragility to contact (applying light force). These samples were heat treated at 1260 ° C for 24 hours. Microstructure analysis by scanning electron microscopy revealed that the titania-containing structure had a coarser microstructure. Titania had a strong negative impact in post-use maintainability of calcium silicate fibers. At the level of 1.5% by weight, titania caused material particle growth and showed very high post-use crushability (ie low mechanical strength). On the other hand, the post-use crushability of the zirconia-containing fiber was improved as compared with the titania-containing fiber at short-term heating (shorter than about 1 month).<u style="single">Relationship between viscosity and temperature</u>The shape of the viscosity-temperature curve of the glass composition represents the ease of fibrosis of the melt and therefore the quality of the resulting fibers (eg, the shot content of the fibers, the diameter of the fibers and of the fibers. Length). Glass generally has a low viscosity at high temperatures. As the temperature decreases, the viscosity increases. Viscosity values at a given temperature vary as a factor in the composition, resulting in a steep viscosity-temperature curve throughout. One of the test methods for whether a fiber of a given composition can be easily produced at an acceptable quality level is that the experimental chemical viscosity curve is that of a known product that can be easily fiberized. It is to measure whether it is comparable. Viscosity curves of such interest are shown in FIG. 1A (viscosity curve of commercially available spun aluminosilicate fibers) and FIG. 1B (viscosity curve of commercially available blown aluminosilicate fibers). Figure 2 shows 75% SiO₂, 5.5% ZrO₂, And a viscosity curve for the chemistry of the magnesia-zirconia-silica fiber melt consisting of 19.5% MgO (% by weight). The noisy region of the curve from 1800 to 1900 ° C is thought to be due to the initiation of phase separation or solidification. Figure 3 shows 70% SiO₂, 5.5% ZrO₂, And a similar curve of the chemistry of the melt containing 24.5% MgO. SiO from the comparison of Fig. 2 and Fig. 3₂It is shown that the viscosity increases as the level decreases by 5%, but the curve does not approach the desired viscosity curve in Figure 1A. Figure 4 shows 1% by weight Al₂O₃Is shown in the effect of adding to the composition of FIG. Al₂O₃A small amount of addition changes the viscosity curve downwards and shifts the phase separation region towards lower temperatures. Although not shown here, a similar viscosity shift is a small amount of B₂O₃Observed with the addition of (up to about 1% by weight). Magnesia-zirconia-silica compound SiO₂And Al₂O₃By adjusting both levels, 72.3% by weight SiO₂, 5.4% by weight ZrO₂, 21.3% by weight MgO and 1% by weight Al₂O₃A viscosity curve for the molten compound (Fig. 5) can be obtained, and the shape between 1800 ° C and 2000 ° C (effective spinning range) is almost the same as the viscosity curve of the aluminosilicate spun compound shown in Fig. 1A. It is the same. At such low levels, Al₂O₃And B₂O₃Additives show minimal effect on the fiber use properties of the present invention, but are effective in adjusting melt viscosity and improving fiber properties. FIG. 6 shows the viscosity curve for a magnesia-zirconia-silica fiber melt compound containing 73.5% by weight silica, 23% by weight magnesia and 3.5% by weight zirconia. Figure 7 shows the viscosity curves for magnesia-silica fiber melt compounds containing 73.5% by weight silica and 26.5% by weight magnesia. These curves are similar to the objective viscosity curves in Figure 1B for commercially available blown aluminosilicate fibers. These fiber melt compounds of the present invention are well suited for fibrosis by conventional blowing or spinning techniques. Example 3 The non-durable refractory glass fibers of the present invention having the desired shrinkage and mechanical strength properties at an operating temperature of at least 1260 ° C are from the melts that produce the compositions shown in Table 2 below. Suitable for fibrosis.<img file="JP3676818B2_D0002.tif" />The non-durable refractory glass fibers of the present invention are about 65 to about 85% by weight silica, about 14 to about 35% by weight magnesia, 0 to about 11% by weight zirconia, 0 to about 3% by weight alumina and It is preferable to use 0 to about 2% by weight of boria as an essential component. Fibers containing less than about 2% by weight of alumina exhibit better properties. In a more preferred range, non-durable refractory fiberglass is about 69 to about 80% by weight silica, about 20 to about 31% by weight magnesia, 0 to about 7% by weight zirconia, 0 to about 2% by weight. A product consisting of alumina and 0 to about 1% by weight of boria is an essential ingredient. In the most preferred range, non-durable refractory fiberglass is about 70-about 79% by weight silica, about 20-about 29% by weight magnesia, about 1-about 5% by weight zirconia, 0-about 1.5% by weight. A product consisting of alumina and 0 to about 1% by weight of boria is an essential ingredient. In the melts and fibers of the present invention, feasible silica levels range from about 65 to about 86% by weight, and upper limit levels are limited only by manufacturability. This is contrary to conventional wisdom (ie, fibers with silica levels above about 70% are not manufacturable). The fibers of the present invention are preferably substantially free of alkali metals (more than trace amounts of impurities). The alkali metal content of these fibers is generally within the range of trace amounts or at most 1/100 of the percentage (%) when calculated as alkali metal oxides. Other impurities include calcia (less than about 1% by weight or as low as possible), and iron oxide (Fe).₂O₃Is calculated as less than about 0.4% by weight or as low as possible). In a series of tests, the following refractory fiber compositions were produced by either spinning or blowing methods and tested for their thermal properties at 1260 ° C. and their solubility in SLF. The individual compositions are listed in Table IIIA and their thermal properties and solubility data are detailed in Table IIIB below.<img file="JP3676818B2_D0003.tif" /><img file="JP3676818B2_D0004.tif" /><img file="JP3676818B2_D0005.tif" /><img file="JP3676818B2_D0006.tif" />From the test performed on the zirconia-containing magnesium silicate fiber of Example 4, the fiber showed shrinkage of only 4.3% after 24 hours at 1260 ° C, 60.4 ng / cm.²It was found that mechanical maintainability was preferred compared to conventional refractory ceramic fibers with a dissolution rate of -hr and similarly treated high mechanical strength (Comparative Examples C, D and E). .. Other examples of the present invention that exhibit weak shrinkage at use or working temperature include Examples 5-8, 10-12 and 25-39. Comparative Examples 13 to 16 in which the component range is outside the range of the present invention show stronger shrinkage at the operating temperature. We have found that certain non-durable refractory glass fibers of the present invention exhibit very weak shrinkage on the order of about 4.5% or less after exposure to operating temperature and contain alumina as a viscosity modifier. Manufactured from melts containing compositions containing from about 69.75 to about 73.5% by weight silica, from about 16.75 to about 22.25% by weight magnesia, from 0 to about 7.5% by weight zirconia, and from about 1 to about 3% by weight alumina. It was characterized as being. The inventors further show that certain non-durable refractory glass fibers of the present invention exhibit very weak shrinkage on the order of about 4.5% or less after exposure to operating temperature, with alumina and boria as viscosity modifiers. Contains about 71.5 to about 73.5% by weight silica, about 19 to about 21.5% by weight magnesia, about 5 to about 6% by weight zirconia, about 0.5 to about 2% by weight alumina and about 0. It was characterized as being made from a melt containing a composition containing 2 to about 1% by weight of boria. The post-use microstructure of the fibers produced according to the method of the invention is of particle size according to the test method described above after exposure to a temperature of 1260 ° C. as shown in Example 12 of Table III. The test was conducted. This was compared with titania-containing calcium silicate fibers containing the composition of Comparative Example B above, and refractory AZS (Comparative Example C) and kaolin (Comparative Example D) ceramic fibers. The test results are shown micrographs in Figures 8-13. The titania-calcium-silicate fibers of Comparative Example B (FIG. 10) are the conventional refractory ceramic fibers of Comparative Examples C (FIG. 8) and D (FIG. 9) as well as the fibers of the present invention, Example 12 (FIG. 12). 11) Compared with both, it was very crushable, showing remarkable surface roughness and large surface crystal grain size. The fibers of Example 12 of the present invention showed a smooth surface and relatively small surface crystals. Surface roughness and large surface crystals are undesirable due to the friability of the fibers and low mechanical strength. However, the SLF-soluble fibers of the present invention, whose crushability was significantly reduced after use, show a very fine particulate microstructure, and the crystal particle size is usually shown in Table III (Examples 4, 5, 12, 17). As shown in ~ 19 and 21 ~ 24) 1. It has an order of 9 microns or less. Comparative Example B, which is a titania-calcium-silicate fiber, and Comparative Example 20, which is a magnesia-zirconia-silicate fiber and is outside the scope of the composition of the present invention, showed a larger particleized post-use microstructure. FIG. 12 shows small particulate crystals in cross section (both in the absolute sense of the term and in fiber diameter) that are present after the fibers of the invention have been exposed to an operating temperature of 1260 ° C for 24 hours. There is. This high mechanical strength fiber exhibits approximately the same crystal size as the very strong AZS fiber after being exposed for 24 hours at an operating temperature of 1426 ° C, as shown in the cross section of FIG. .. In a series of tests, the following refractory fiber compositions were produced by blowing technology and tested for thermal properties and solubility in SLF at 1260 ° C. Each composition is listed in Table IVA and its thermal properties and solubility are shown in detail in Table IVB below.<img file="JP3676818B2_D0007.tif" /><img file="JP3676818B2_D0008.tif" /><img file="JP3676818B2_D0009.tif" /><img file="JP3676818B2_D0010.tif" />Among the non-durable fibers produced by the blowing technique of the present invention, the best thermal properties are produced by blowing formation from a molten composition having about 70% or more silica and showing a fiber index of about 35 or more. And obtained from fibers having a diameter of about 2 microns or more. A substantial upper limit to the fiber diameter of the present invention is the ability to spin or inject a product with the desired diameter, a property obtained from fiber diameters up to about 10 microns. Particularly preferred compositions for forming fibers from the melt include those containing from about 70 to about 77.5% by weight silica, from about 15.5 to about 30% by weight magnesia, and from 0 to about 6% by weight zirconia. Be done. Suitable melt compositions for forming textile products are about 73.5% by weight silica, about 23 to about 26.5% by weight magnesia, 0 to about 3.5% by weight zirconia, and about 0.15 to about 0.3% by weight calcia impurities. And about 0.32 to about 1.86% by weight, usually about 0.32 to about 0.92% by weight of alumina impurities. These fibers exhibit good shrinkage, including delta shrinkage or daily and weekly shrinkage changes at operating temperature, as shown in the shrinkage data in Table IVB. This fiber exhibits significant solubility in SLF as shown in Table IVB. 54 to 1450 ng / cm by the method described above²Solubility above -hr was measured. (+ In the table indicates the dissolution rate of fibers that are very rapid and undetectable. The values shown indicate the lower limit of the dissolution rate of the sample.) Non-durable, low of the present invention. Shrink fire resistant glass fibers were compared to conventional kaolin, AZS and aluminosilicate durable fire resistant ceramic fibers in terms of mechanical strength after exposure to operating temperature. The fibers of the present invention were generally tested in a range equivalent to that of kaolin fibers in a 50% compression strength test and a compression recovery test. The fibers of the present invention show significantly improved mechanical strength (measured as compressive strength and compressive recovery) compared to the titania-calcium-silicate fibers of Comparative Experiment B. Magnesium silicate modified by adding a specific ratio of zirconia is an essential ingredient, and Al₂O₃And B₂O₃The refractory glass fibers of the present invention, which optionally contain a viscosity modifier additive such as, and exhibit a finely particulate microstructure after exposure to an operating temperature of 1260 ° C, are compared to standard refractory ceramic fibers. , Shows up to 150-fold solubility in pseudopulmonary fluid. It is also durable to temperatures above 1000 ° C and up to 1260 ° C, with linear shrinkage less than 6%. The SLF-soluble fibers of the present invention exhibited significantly reduced post-use crushability, i.e. high mechanical strength, compared to the highly stable SLF-durable aluminosilicate and alumino-zirconia silicate fibers. The fibers of the present invention generally exhibit a fine microstructure, low friability, high mechanical strength, weak shrinkage when exposed to operating temperature, and high solubility in SLF. Therefore, the fibers of the present invention exhibit the advantageous use characteristics of conventional refractory ceramic fibers, such as aluminosilicate fibers, that is, the property of causing limited shrinkage at high operating temperatures. The refractory glass fiber of the present invention exhibits a shrinkage of less than about 6% at an operating temperature of 1260 ° C and retains good mechanical strength after use. The fibers of the present invention exhibit weak post-use crushability, exhibit small or finely particulate microstructures after initial exposure to operating temperature, and exhibit high compressive strength and compressive recovery. The fibers of the present invention may be formed into various products including, but not limited to, sewn blankets, papers, felts and bulk fibers manufactured by existing fibrosis techniques. In addition to conventional refractory ceramic fibers, the fibers of the present invention are 4 to 150 times more soluble in simulated lung fluid, thus minimizing problems with fiber inhalation. As described above, although the object is achieved by the present invention, the present invention is not limited to the specific embodiments described above, and includes various improvements and equivalent embodiments described in the following claims. ..