MXPA06010510A - Glass yarn for reinforcing organic and/ or inorganic materials - Google Patents

Abstract

The invention relates to reinforcing glass yarns whose composition comprises the following components within the limits defined thereafter in percentages by weight:SiO2 58 - 63%, AL2O3 10 - 16%, CaO 16 - 23%, MgO 0.5 3.5%, Na2O + K2O + Li2O 0 - 2%, TiO2 1 1.5%, B2O3 0 1.5%, Li2O 0 0.4%, ZnO 0 0.4%, MnO 0 - 1%, F 0 0.5%. The inventive yarns exhibit improved mechanical, acid and high-temperature resistance for the low cost composition thereof. A method and a composition for producing said yarns are also disclosed.

Description

GLASS FIBERS CAPABLE OF REINFORCING ORGANIC AND / OR INORGANIC MATERIALS The present invention relates to glass strips or fibers, especially those designed to reinforce organic and / or inorganic materials and capable of being used as textile fibers, these fibers being capable of being produced by a method that consists in mechanically attenuating the streams of molten glass that emanate from the holes placed in the base of a bushing, usually heated by a resistance heater.

The invention relates more particularly to glass fibers having a particularly advantageous new composition.

The field of reinforcing glass fibers is a particular field of the glass industry. These fibers are produced from specific glass compositions, the used glass having to be attenuated in the form of filaments of a few microns in diameter, using the procedure described above, and must allow for formation. of fibers able in particular to fulfill their role of reinforcement. The most commonly used reinforcing glass fibers are therefore fibers formed from glass whose composition derives from the eutectic composition of the ternary diagram of SiO2-Al203-CaO, whose liquid temperature is 1170 ° C. These fibers are known as "glass fibers E", whose archetype is described in the publications of US-A-2 334 981 and UA-2 571 074, fibers having a composition essentially based on silica, alumina , lime and boric anhydride. This last compound, present with contents that in the practice are in the proportion of from 5 to 13% in the glass compositions for the "E glass", is added as a replacement for the silica so that the liquid temperature is reduced of the formed glass • and the fusion of the glass is facilitated. The term "liquid temperature", denoted as? Iíq, is the temperature at which, in a system 'in thermodynamic equilibrium, the most refractory crystal appears. The liquid temperature therefore gives the lower limit to which the glass fiber is possible. The glass fibers E are also characterized by a limited content of alkali metal oxides (essentially Na20 and / or K20).

In the two patent applications mentioned above, the glasses comprising these constituents have undergone numerous modifications with the purpose of reducing the emissions of products capable of contaminating the atmosphere, or of reducing the cost of the composition by decreasing the content of the constituents. costly, to improve the ability of these glasses to tolerate the fiber (fibred or formation corresponding to the operation of attenuating the glass filaments that come from "a bushing using the procedure described above), especially reducing its viscosity at high temperatures and its tendency to devitrify itself, or finally to improve a particular property designed to increase, its performance (or to make it suitable) for certain applications.

The solutions to reduce polluting emissions have consisted in eliminating the most volatile elements from the compositions, such as boric anhydride and fluorine. Decreasing the boric anhydride content is also a means of reducing the cost of the compositions. The removal of boric anhydride and fluorine in the compositions of these glasses is generally detrimental to their fibrillation capacity and their processing to obtain reinforcing fibers, which is generally made more difficult or misleading, possibly requiring modifications in the installations of existing fiber.

US-A-3 847 626 discloses and claims compositions in which these elements have been replaced with high contents of titanium oxide, in a proportion of from 3 to 5%, and with magnesia, in proportions of from 1.5. up to 4%. These two oxides make it possible to compensate for the absence of boron and fluorine, making the glasses formed from these compositions suitable for the bundle. However, the yellow coloration conferred by these titanium levels tends to exclude. to this type-of composition for certain applications. The high contents of titanium oxide, in a proportion of from 2 to 4%, are also recommended in Publication US-A-4 026 715, this constituent being added generally together with divyale oxides such as SrO, ZnO or BaO, which They also have the disadvantage of being expensive.

US-A-4 199 364 discloses compositions having high contents of lithium oxide. Apart from its high cost, lithium oxide is part of the alkali metal oxides, which are known to degrade the ability of fibers to strengthen the substrates of electronic circuits.

Application WO 96/39362 describes compositions containing neither boron nor fluorine, which are formed, essentially from the quaternary system SiO2-Al203- n CaO-MgO, which contain small amounts of titanium oxide (less than 0.9%) and which generally do not contain additions of expensive oxides such as those described in the aforementioned applications. However, these, glasses have a liquid temperature and a formation temperature that are relatively high.

In the field of glass fibers obtained by mechanical attenuation. of the molten glass streams, the term "forming temperature" is the temperature for which the glass has a viscosity of 1000 poise (decipascal, second), viscosity around which the glass must be fibred. This temperature, denoted as Tiog3, corresponds more particularly to the temperature of the glass in the bushing nipples. The temperature of the glass when entering the bushing corresponds to a viscosity of the order of 102 5 poise, and is denoted as Tj.og2.5.

To avoid any risk of devitrification during formation, the "fibrate range", denoted as ΔT and defined as the difference between the formation temperature and the liquid temperature, should be positive and preferably greater than 50 ° C.

The high values of these various temperatures require that the glass be maintained at high temperatures both during the conditioning of the glass and in the fiber-forming device itself.

This drawback results in an additional cost due to the additional supply of the heat required to condition the glass and the more frequent renewal of the fiber tools, especially the parts made of platinum, whose aging is • greatly accelerates with the increase in temperature.

More recently, several applications have also described compositions for obtaining low cost glasses, which have liquid and formation temperatures close to those of the E glass, which therefore allow them to be fibrated more easily.

"Thus, the Patent Publications WO 99/12858 and WO 99/01393 disclose glass compositions containing small amounts of fluorine or boron oxide. In Publication WO 00/73232, the decrease in "characteristic temperatures is achieved through compositions having a low MgO content (less than 1%) and with the addition of a certain amount of boron oxide or oxide. of lithium or zinc oxide or even manganese oxide, thereby decreasing the economic advantage of these compositions, WO 00/73231 discloses compositions whose liquid temperature is lowered, especially by the addition of MgO within a narrow content ratio, between 1.7 and 2.6% Most of the compositions exemplified in the above application further include an oxide selected from boron oxide, lithium oxide, zinc oxide or even manganese oxide. the characteristic temperatures of the process can also be achieved, in WO 01/32576, by the low silica contents (less than 58%) of the compositions, and in the 'Public WO 02/20419, selecting compositions whose content ratio of silica / alkaline earth metal content is less than 2.35.

The objectives pursued by the various inventions mentioned above were mainly to reduce the cost of compositions and to reduce the amount of • environmentally hazardous materials discharged. The use of fibers for certain applications has also dictated the choice of very specific compositions. Thus, three properties of the fibers must be sought in particular: acid resistance, resistance to high temperatures and high mechanical resistance, especially resistance to tension. The first property is particularly desired in applications of reinforcement of organic and / or inorganic materials that come into contact with an acidic medium, for example in the chemical industry. The second property is of supreme importance when glass fibers are used, for example, in exhaust systems for motor vehicles. The third property is sought when the materials reinforced by the. Glass fibers are subjected to high mechanical stresses.

For each of these properties, particular compositions have been developed.

Publications WO 03/050049 and WO 02/42233 disclose glass fibers such that their composition makes them suitable for use in motor vehicle exhaust systems. In the first application, the objective is achieved thanks to a glass composition containing very small amounts (less than 1%) of MgO. These glasses also have high contents (at least 1.5%) of titanium oxide. The second application describes glass compositions containing a particular proportion of alkaline earth metal oxide contents. Many examples of this application are glasses containing barium oxide or strontium oxide. FR-A-2 804 107 describes fibers having a particular composition, whose high temperature resistance property is derived from a surface treatment thereof for the purpose of obtaining an extremely silica-enriched surface composition.

Application FR-A-2 692 248 describes and claims glass compositions which behave, during melting and during framing, in a manner similar to glass E but which have a resistance markedly superior to acid, especially thanks to the reduction of the contents of boric anhydride and alumina. However, the claimed glasses have a boric anhydride content greater than 2%.

The examples - above show that specific compositions have been developed to meet certain technical, economic or environmental constraints, but that the optimization of a single range of compositions that allow compliance with all these restrictions, which are highly desirable, is not yet achieved. from the industrial point of view.

Therefore, an object of the present invention is to propose advantageously low cost glass compositions which show good formability and which make it possible to obtain glass fibers with properties of high temperature resistance, acid resistance and mechanical strength are significantly improved on E glass or on certain glasses currently available. 1. Another objective of the invention is to propose glass compositions which, when. be fused, release few emanations susceptible to damage the environment.

These objectives are achieved thanks to fibers of glass whose composition comprises the following constituents in the limits defined below, expressed as percentages by weight: Si02 58 to 63 A1203 10 to 16 CaO 16 - less than 23 MgO. 0.5 to less than 3.5 Na20 + K20 + Li20 0 to 2 Ti02 greater than 1 but less than 5 B203 0 to 1.5 Li20 O to 0.4 ZnO 0 to 0.4 MnO 0 to 1 F 0 to 0.5 Silica is an oxide that acts as a glass network former, and plays an essential role in the stabilization of glass. Within the limits defined above, when the percentage of this constituent is less than 58%, the glass obtained is not sufficiently viscous and is very easily devitrified during the bundling. For contents above 63%, the glass becomes very viscous and difficult to melt. Accordingly, the silica content is preferably less than 62% and particularly preferably less than 61%. Since silica plays an essential beneficial role in resistance to acid corrosion, its content is preferably greater than 59%, and still strictly greater than 60%. Silica contents strictly greater than 60%, but not exceeding 63%, are therefore preferable, in particular, but not exclusively, when there is a boron content other than zero.

The alumina also constitutes a network former in the glasses according to the invention, and plays a fundamental role in its stability. Within the limits defined in accordance with the invention, a content of less than 10% causes a substantial increase in the hydrolytic attack of the glass, while increasing the content of this oxide to above 16% rises the risk of devitrification and a. increase in viscosity. Due to its detrimental effect on the acid corrosion properties, the alumina content is preferably kept below 15% or even 14%. The greatest resistance to devitrification is obtained for the alumina contents of between 11 and 14%, preferably between 12 and 13%.

The lime and magnesia make it possible to adjust the viscosity, and control the devitrification of the glasses according to the invention. Within the limits defined in accordance with this invention, a content of CaO of 23% or greater results in an increase in levels of devitrification towards CaSi03 (wollastonite), which is detrimental to good fiber formation. Therefore the content of CaO must be kept at a value strictly less than 2. 3%. A CaO content of less than 16% results in one. too low hydrolytic resistance. Therefore the • CaO content is preferably greater than 18%, even higher than 20% or - in fact 22%. The MgO content, together with the lime content, makes it possible to obtain glasses whose liquid temperature is particularly low. This is because the addition of magnesia in the defined contents makes it possible to introduce a competition between the development of wollastonite and diopsid crystals (CaMgSi206), this having the effect of reducing the growth level of these two crystals, and therefore to give good resistance to devitrification. The MgO content is preferably maintained at 3% or less, especially below 2.5%, but greater than 1%, especially greater than 2%. For contents of 3.2% or greater, especially 3.5%, the level of crystallization of the diopside becomes too great. For this reason, the MgO content of the glasses according to the invention is strictly less than 3.5%, and especially 3.2% or less. A particularly preferable proportion of values corresponds to the MgO contents in the range of 2.2 to 2.8%. In another preferred embodiment, the MgO content is more moderate, particularly between 0.5 and less than 2%.

The alkali metal oxides can be introduced into the compositions of the glass fibers according to the invention, to limit the devitrification and reduce the viscosity of the glass. However, the alkali metal oxide content should not exceed 2% to avoid an unacceptable increase in electrical conductivity for applications in the electronics field and to avoid a harmful reduction in the hydrolytic resistance of the glass. The content of lithium oxide must be kept especially below 0. 4% and preferably below 0.1%. The inventors have demonstrated the extremely detrimental role of alkali metal oxides in the resistance to high temperature. This paper is known in general, but within this particular context the effect on the reduction of the characteristic temperatures at which the glass is softened, due to the very low contents of alkali metal oxide, has become impressively large. ' For the. thus, the total content of alkali metal oxides does not preferably exceed 1.5%, or even 1%.

Ti02 plays a particularly important role in the glasses according to the invention. This oxide is known as a flow promoter for glass, and is able to reduce the liquid temperature, and thereby partially replace the boron oxide. The inventors have also demonstrated their especially beneficial role with respect to the properties of resistance to high temperature, the properties of resistance to acid and also the properties of resistance to stress. For the contents of 1.5% or greater, the Yellow coloration and the additional cost it generates may unfortunately become unacceptable for many applications. Ultraviolet absorption due to high titanium contents may also be unacceptable when the fibers are designed to reinforce polymers. that are cross-linked by means of UV radiation. In addition, glasses that have titanium oxide contents greater than 1.5% can not benefit from the name "E glass", as defined by the ASTM D578 standard. For these various reasons, the titanium oxide content of the glasses according to the invention is strictly less than 1.5% and preferably 1.4% or less. To benefit from the advantages provided by the presence of titanium oxide in the glasses according to the invention, their content is necessarily strictly greater than 1%, and preferably not less than 1.1%.

The boric anhydride B203 is advantageously added to the composition of the glasses according to the invention, in a moderate content in order to facilitate the melting and forming of the glasses, but to the detriment of the cost of the composition. Therefore boron can be introduced in a moderate amount, and economically, with the incorporation, as a starting material, of glass fiber waste containing boron, for example, wastage of glass fiber E. However , since the inventors have demonstrated their detrimental role in the acid corrosion properties and the high temperature resistance properties, the B203 content does not preferably exceed 1%, and more preferably does not exceed 0.5%. In a particularly preferred embodiment of the invention, the content of B203 is still less than 0.1%. '' Zinc oxide (ZnO) is used to reduce the viscosity of the glasses according to the invention and to increase their resistance to acid corrosion. However, due to the high cost of this oxide, its content is less than 0.4%, preferably less than 0.1%.

The content of manganese oxide is less than 1% and preferably less than 0.3%. Since this oxide is prone to give the glass an intense violet coloration, the MnO content is preferably maintained below the 0. 1%.

Fluorine may be added in a small amount to improve the melting of the glass, or it may be present. as an impurity. However, it has been discovered that small amounts of fluorine affect the temperature resistance of the glasses according to the invention, in a very marked manner. Therefore, the fluorine content is advantageously maintained below 0.5% and especially below 0.1%.

Iron oxide is an unavoidable impurity in glasses according to the invention, due to its presence in various materials of the heading, and its content is generally less than 0.5%. Since the coloring effect generally attributed to titanium is in fact due to the transfer of electrons between the Fe2 + and Ti4 + ions, the iron content in the glasses according to the invention is advantageously less than 0.3%, especially less than 0.2 %, thanks to a judicious choice of the materials of the game.

In the composition according to the invention one or more other components (differing from those already considered, ie, different from SiO2, A1203, CaO, MgO, Na20, K20, Li20, B203, TiO2, F) may also be present. , Fe03, ZnO, MnO), generally as impurities, remaining the total content of these other components less than 1%, preferably less than 0.5%, generally not exceeding 0, 5% the content of each of these other components . ' According to a preferred embodiment, the glass fibers according to the invention contain small amounts of cobalt oxide designed to compensate for the yellow dye due to the titanium oxide. The preferable content of cobalt oxide (expressed in the form of CoO) falls between 10 and 100 .ppm, especially between 15 and 60 ppm, and advantageously between 15 and 50 ppm (i.e., between 0.0015 and 0.0050%).

The glass fibers according to the invention can be produced and used as glass fibers E. They are also less expensive and show better resistance to temperature, resistance to acid corrosion and resistance to stress.

The glass fibers according to the invention are obtained from glasses with the composition described above using the following procedure: a multiplicity of molten glass streams emanating from a multiplicity of dispersed holes on the base of one or more bushings, they are attenuated in the form of one or more continuous filament networks, and then assembled, into one or more fibers that are collected on a mobile support. This can be a rotating support when the fibers are collected in the form of agglutinated packages, or a support that moves translationally when the fibers are cut by a member that also serves to attenuate them, or when the fibers are sprinkled by a member that It serves to attenuate them to form a mat.

The fibers obtained, optionally after other conversion operations, can therefore be in various forms, namely continuous fibers, staple fibers, braids, tapes, mats, nets, etc., these fibers being composed of filaments with a diameter possibly 'on the scale from 5 to 30 microns, approximately.

The molten glass that feeds the bushings is obtained from starting materials that can be pure (for example, coming from the chemical industry) but are often natural, sometimes containing these materials impurities in small quantities and being mixed in adequate proportions to obtain the desired composition, and then cast. The temperature of the molten glass (and therefore its viscosity) is conventionally established by the operator to allow the glass to be fibred, while in particular the problems of devitrification are avoided, so that the best possible quality of the glass is obtained. glass fibers. Before being assembled in the form of fibers, the. Filaments are generally covered with an equalizing composition to protect them from abrasion and facilitate their subsequent association with the materials to be reinforced.

The compounds obtained from the fibers according to the invention comprise at least one organic material and / or at least one material, inorganic and glass fibers, with at least some of the fibers being the glass fibers according to the invention.

Optionally, the glass fibers according to the invention may already have been associated, for example during the attenuation, with filaments of organic material to obtain composite fibers. By extension, the expression "glass fibers whose composition comprises ..." is understood with the meaning, according to the - invention, of "fibers formed from glass filaments whose composition comprises ...", the glass filaments being optionally combined with organic filaments before, that the filaments are assembled as fibers.

Due to their good resistance properties at high temperature, the glass fibers according to the invention can also be used to equip exhaust systems of motor vehicles. In this particular application, the glass fibers according to the invention give good acoustic insulation properties, but they are also exposed to temperatures that may exceed 850 ° C or even 900 ° C.

The advantages provided by the glass fibers according to the invention will be more fully appreciated through the following examples, which illustrate the present invention, without however limiting it.

Table 1 gives four examples according to the invention, numbered from 1 to 4, and three comparative examples, numbered from Cl to C3. Cl is a standard glass composition E, and C2 is a composition derived from Patent Application WO 99/12858, while C3 is in accordance with the teaching of Application WO 96/39362.

• The composition of the glasses is expressed as percentages by weight of the oxides. X To illustrate the advantages of the glass compositions according to the invention, Table 1 presents three fundamental properties: - the temperature corresponding to a viscosity of 102.5 poise, denoted as T? Og2.5 and expressed in degrees Celsius, close to the temperature of the glass in the bushing; - the smoothing temperature or smoothing point of Littleton, corresponding to a viscosity of 107 '? poise, denoted co or T '? og .6 and expressed in degrees Celsius, this value being indicative of the resistance of the fibers to temperature, these two values of temperature and their respective measurement method being well known to those experienced in the technique; Y - the value of the failure stress in bending at three points of the compounds based on vinyl ester resin (sold by Dow Chemical Company under the name of Derakane 411-350) comprising a fraction of 50% of the fiber volume after immersion in a solution of hydrochloric acid (1N HCl) at room temperature for 100 hours. The stress is expressed in MPa and-characterizes the resistance of the fibers to acid corrosion, As indicated in Table 1, the fibers according to the invention are substantially substantially superior to glass fibers E (Comparative Example Cl) in terms of temperature resistance (the difference of about 100 ° C) and of resistance to acid corrosion (a fault voltage at least two or three times higher).

For similar fiber conditions, the performance of the fibers according to the invention is also improved over comparative examples C2 and C3. The positive role of Ti02 in thermal performance and acid resistance is particularly demonstrated by comparing Example 2 according to the invention with Comparative Example C3, whose compositions differ mainly in their content of titanium oxide.

Compared to Example 1, Examples 2, 3 and 4 illustrate the influence of certain oxides on the resistance of the fibers to acid corrosion. Example 2, for example, illustrates the beneficial role of Si02 and the deleterious role of A1203, while Examples 3 and 4 show the deleterious influence of boron oxide. The impact of the preferable silica contents strictly greater than 60% is illustrated by comparing Examples i and 2, Example 2 having markedly improved resistance to acid corrosion.

The glasses according to the invention therefore have significantly improved properties in terms of temperature resistance and resistance to acid corrosion, while still retaining acceptable fibrous properties.

To illustrate the influence of cobalt oxide on the coloration of the glass fibers according to the invention, and therefore on the coloration of the organic materials reinforced with these fibers, in the composition of Example 2 were made respective additions of 20 , 40 and 60 ppm of CoO.

. - Table 2 gives the colorimetric results obtained. The chromatic coordinates L *, a *, and b * were calculated from the experimental spectrum in the transmission, taking as reference the illuminant Dßs and the reference observer "CIÉ 1931 !, as defined in the ISO / CIE 10526 standards and 10527, respectively.

Table 2 A content of cobalt oxide of between 20 and 40 ppm makes it possible, therefore, to obtain a colorimetric appearance similar to that obtained with the reference composition Cl.

Claims (9)

1. CLAIMS . 1. Fiberglass, characterized in that its composition comprises the following constituents in the limits defined below, expressed as percentages by weight: Si02 58 to 63 A1203 10 to 16 - CaO 16 to less than 23 MgO of 0.5 to less than '3.5 Na20 + K20 + Li20 0 to 2 Ti02 greater than 1 but less than 1.5 B203 0 to 1.5 Li20 0 to 0.4 ZnO 0 to 0.4 MnO 0. to 1 F 0 to 0.5 2. Fiberglass according to claim 1, characterized in which the content of SiO2 is strictly greater than 60% '3. Fiberglass according to claim 1 or 2, characterized in that the content of TiO2 is greater than or equal to 1.1% and less than or equal to 1.4% . Fiberglass according to one of the preceding claims, characterized in that the content of MgO is between 2.2 and 2.8%. 5. Fiberglass according to one of the preceding claims, characterized in that the content of anhydride boricum (B203) does not exceed 0.5% 6. Fiberglass according to one of the preceding claims, characterized in that its composition further contains between 10 and 100 ppm of cobalt oxide (CoO). 7. Compound, consisting of glass fibers and organic (s) and / or inorganic material (s) -, characterized in that it comprises glass fibers as defined in one of claims 1 to 6. 8. Attachment for an exhaust system, characterized in that it comprises fibers as defined in one of claims 1 to 6. 9. Glass composition suitable for producing reinforcing glass fibers, comprising the following constituents within the limits defined below, expressed as Percentages by weight: Si02 58 to 63 A1203 - 10 to 16 CaO - 16 to less than 23 MgO of 0.5 to less than 3.5 Na20 + K20 + Li20 0 to 2 Ti02 greater than 1 but less than 1.5 B203 '0 to 1.5 Li20 0 to -0.4 ZnO. 0 to 0.4 MnO 0 to 1 F 0.a 0.5 10. Procedure for manufacturing glass fibers, which. it comprises the attenuation steps in the form of one or more networks of the continuous filaments of a multiplicity of molten glass streams emanating from __ a multiplicity of holes placed in the base of one or more bushings, and of assembling the filaments in one or more fibers that are collected on a mobile support, the molten glass that feeds the bushings having a composition according to claim 9.