MXPA06010508A - 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 59 - 63%, AL2O3 10 - 16%, CaO 16 - 23%, MgO 1 3.2%, Na2O + K2O + Li2O 0 - 2%, TiO2 0 - 1%, B2O3 0.1 - 1,8%, Li2O 0 0.5%, 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 FOR REINFORCING ORGANIC AND / OR INORGANIC MATERIALS The present invention relates to glass strips or fibers, especially those designed for the reinforcement of organic and / or inorganic materials. and capable of being used as textile fibers, these fibers being capable of being produced by a process consisting of mechanically attenuating the molten glass streams emanating from the orifices placed in the base of a bushing, generally 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 compositions of glass, the used glass having to be capable of being attenuated in the form of filaments of a few microns. in diameter, using the procedure described above, and must allow the formation of fibers capable, in particular, of fulfilling their role of reinforcement. The most commonly used reinforcing glass fibers are therefore fibers formed from glasses whose composition derives from the eutectic composition of the ternary Si02-Al203-CaO diagram, whose liquid temperature is 1170 ° C. These fibers are known as "glass fibers E", whose archetype is described in Patent Publications 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 coh contents that in 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 odo silica to reduce the liquid temperature of the glass formed and the fusion of the glass is facilitated. The term "liquid temperature", denoted as Tiig, is the temperature at which, in a system in thermodynamic equilibrium, the most refractory crystal appears. The liquid temperature therefore gives the lower limit at which it is possible to make fiber from the glass.

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 referred to 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, or to improve the ability of these glasses to tolerate the bundle (bundle or formation corresponding to the operation of attenuating the glass filaments coming from a bushing using the procedure described above), especially by reducing its viscosity at high temperatures and its tendency to devitrify, or ultimately improve, a particular property designed to increase its performance (or to make it suitable) for certain applications.

The solutions to reduce the polluting effluents mainly have been to eliminate the most volatile elements from the compositions, these being the boric anhydride and the 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 capacity of fiberization and their processing to obtain de-reinforcing fibers, which generally becomes more difficult or deceptive, possibly requiring modifications in the existing fiberglass installations.

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 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 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 ication US-A-4 026 715, this constituent generally being added together with divalent oxides such as SrO, ZnO or BaO, which have besides 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 no boron or fluorine, which are formed essentially from the quaternary system Si02-Al203-CaO-MgO, which contain small amounts of titanium oxide (less than 0.9%) and which they 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 Tlog2.5.

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 fibrillating 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 accelerated with the increase of the temperature.

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

Thus, 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 lithium oxide. or zinc oxide or even manganese oxide, thereby decreasing the economic advantage of these compositions. Publication WO 00/73231 describes compositions whose liquid temperature is decreased, especially thanks to 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 reduction in the characteristic temperatures of the process can also be achieved, in Publication WO 01/32576, by the low silica contents (less than 58%) of the compositions, and in Publication WO 02/20419, by selecting compositions whose proportion of silica content / alkaline earth metal content is less than 2.35.

The objectives pursued by the various inventions mentioned herein were mainly to reduce the cost of the 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: acid resistance, resistance to high temperatures and high mechanical resistance, especially resistance to tension. The first property is particularly desired n reinforcement applications 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 that behave, during melting and during fiberglassing, in a manner similar to glass E but have a markedly superior acid resistance, especially thanks to the reduction of the contents of boric anhydride and alumina. However, the claimed glasses have a boric anhydride content even greater than 2%.

The above examples show that specific compositions have been developed to comply with certain technical, economic or environmental constraints, but that the optimization of a single range of compositions that allow compliance with all of these restrictions, which are highly desirable from the industrial point of view.

Therefore, an object of the present invention is to propose glass compositions of advantageously low cost which show good formability and which make it possible to obtain glass fibers with properties of high temperature resistance, acid resistance and mechanical resistance which are significantly improved with respect to glass E and / or are similar to certain glasses currently available while showing better formability.

Another object of the invention is to propose glass compositions which, when melted, give off a few emanations capable of damaging the environment.

These objectives are achieved thanks to glass fibers whose composition comprises the following constituents in the limits defined below, expressed as percentages by weight: Si02 59 to 63 A1203 10 to 16 CaO 16 to 23 MgO from 1 to less than 3. 2 Na20 +? 2o + Li; > or 0 to 2 Ti02 0 to 1 B203 0. 1 to 1. 8 Li20 0 to 0. 5 ZnO 0 to 1 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 very devitrifying. easily during the bundle. For contents above 63%, the glass becomes very viscous and difficult to melt. Accordingly, the silica content is preferably less than. 62.5% and in particular preferably less than 62%. Since silica plays an essential beneficial role in resistance to acid corrosion, its content is preferably greater than 60%, especially 60.5% or higher, and even 61%. A particularly preferred compromise is to choose a silica content of between 60 and 61%.

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 according to the invention, a content of less than 10% causes a substantial increase in the hydrolytic binding of the glass, while increasing the content of this oxide to over 16% runs the risk of devitrification and 'of an 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 CaO content of 23% or greater results in an increase in levels of devitrification towards CaSi03 (wollastonite), detrimental to good bundling. Therefore the content of CaO must be kept at a value strictly less than 23%. A CaO content of less than 16% results in too low hydrolytic resistance. Therefore, the CaO content is preferably greater than 18%, even greater than 20%. 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 the diopsid crystals (CaMgSi206), this having the effect of reducing the growth level of these two crystals, and therefore so much to give good resistance to devitrification. The MgO content is greater than 1%. The MgO content is also preferably maintained at 3% or less, but greater than 2%, and especially 2.2% or higher, or indeed 2.6%. For contents of 3.2% or greater, the level of crystallization of the diopside is too great. For this reason, the MgO content of the glasses according to the invention is strictly less than 3.2%.

The alkali metal oxides can be introduced into the compositions of the glass fibers according to the invention, to limit the de-nitration and reduce the viscosity of the glass. However, the alkali metal oxide content should be less than 2% to avoid an unacceptable increase in electrical conductivity for applications in the field of electronics. and to avoid a harmful reduction in the hydrolytic resistance of the glass. E. content, lithium should be kept especially below 0.5% and preferably below 0.1%. The inventors have demonstrated the extremely detrimental role of alkali metal oxides in high temperature resistance, especially characterized by their softening 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. Therefore, the total content of alkali metal oxides does not preferably exceed 1.5%, or even 1%.

Ti02 plays an 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. Beyond 1%, yellow coloration and the additional cost it generates may become unacceptable for certain applications. Ultraviolet absorption due to high titanium content may also be unacceptable when the fibers are designed to reinforce polymers that are cross-linked by means of UV radiation. For these various reasons, the titanium oxide content of the glasses according to the invention is less than 1% and preferably is equal to 0.9% or less, and still 0.8%. To benefit from the advantages provided by the presence of titanium oxide, its content is preferably 0.5% or greater.

The boric anhydride B203 is added to the composition of the glasses according to the invention, in a content greater than 0.1%, in order to facilitate the fusion and the formation of the glasses. In fact, boron can be introduced in a moderate amount, and economically, with the incorporation, as material of the wastage of glass fiber containing boron, for example, waste of fiberglass E. Other Economic means of introducing small amounts of boron consists of using. natural materials of the heading that provide boron oxide and alkali metal oxides, such as, for example, borax (chemical formula: Na2B407.5H20). Since those materials of the heading provide sodium and, due to the limitation of the total content of alkali metal oxide that is desired, the boron oxide content of the glasses according to the invention is strictly less than 1%. However, the inventors have demonstrated their detrimental role in the properties of resistance to acid corrosion and to the properties of resistance to high temperature. Therefore, the content of B203 is preferably less than 1.5%, and even more preferably less than 1.1%. However, it has been discovered that the low boron oxide contents, which are particularly beneficial for melting and forming the glasses according to the invention, do not appreciably degrade the aforementioned properties. A minimum content of 0.5% boron oxide is therefore preferable in the glasses according to the invention. When the content of B203 is greater than or equal to 0.5% and the content of Ti02 is less than 0.5%, it is desirable that the content of SiO2 be greater than 60.5%, to retain good properties of resistance to acid corrosion.

Zinc oxide (ZnO) is used to reduce the viscosity of the glasses according to the invention and to increase their resistance to the. acid corrosion. However, 'due to the high cost of this oxide, its content is lower- 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 color, the MnO content is preferably kept below 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 the 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 (which differ from those already considered, ie, different from SiO2, A1203, CaO, MgO, Na20, K20, Li20, B203, TiO2, F) may also be present. , Fe203, ZnO, MnO), generally as impurities, the total content of these other components remaining less than 1%, preferably less than 0.5%, generally not exceeding 0.5% the content of each of these other components.

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 tensile strength.

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 orifices on the base of one or more bushings, 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 serving member. to soften 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, ribbons, 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 raw 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 get the desired composition, and then melted. The temperature of the molten glass (and therefore its viscosity) is conventionally established by the operator to allow the glass to be fibred, while devitrification problems are avoided in particular, 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 inorganic material and glass fibers, at least some of the fibers being 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 term "glass fibers whose composition comprises ..." is understood with the meaning, according to the invention, of "fibers formed from glass filaments whose composition comprises ...", the filaments being glass optionally combined with organic filaments before the filaments are assembled as fibers.

Due to their good high temperature resistance properties, the glass fibers according to the invention can also be used to equip motor vehicle exhaust systems. 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 five examples according to the invention, numbered from 1 to 5, and three comparative examples, numbered from Cl to C3. Cl is a standard glass composition E, and C2 is a composition that is 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.

To illustrate the advantages of the glass compositions according to the invention, Table 1 presents four fundamental properties: - the temperature corresponding to a viscosity of 102"5 poise, denoted as T? Og2.5 and expressed in degrees Celsius, near at the temperature of the glass in the bushing; - the difference between this last temperature and the liquid temperature (called T ?? q, which represents a training margin that should be as high as possible; - the smoothing temperature or point of • softening of Littleton, corresponding to a viscosity of 107'6 poise, denoted, as Tlog7.6 and expressed in degrees Celsius, this value being indicative of the resistance of the fibers to temperature, being these two temperature values and their respective measurement method are well known to those skilled in the art; Y - the value of the failure stress in three-point bending of the compounds based on vinyl ester resin (sold by the Dow Chemical Company under the name of Derakane 411-350) comprising a fraction of 50% of the fiber volume after of the immersion in a solution of hydrochloric acid (HCl of concentration 1N) 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 much superior to glass fibers E (Comparative Example Cl) in terms of resistance to temperature (difference of about 100 ° C) and resistance to acid corrosion (a fault voltage at least two or three times higher).

The fibers according to the invention have use properties very similar to those of Example C3, but have the advantage of having improved fiber conditions, since the formation margin is appreciably more comfortable (at least 25 ° C higher) and still approaches the conditions of glass E, thanks to the moderate addition of boric anhydride. The fibers according to the invention are, at all points, superior to the fibers of the. Comparative Example C2.

Examples 1, 2 and 3 illustrate the influence of certain oxides on the resistance of the fibers to acid corrosion. Example 2, for example, illustrates, in comparison with Example 1, the beneficial role of Si02 and the deleterious role of A1203, while Example 3 shows, in comparison with Example 2, the deleterious influence of boron oxide.

Examples 4 and 5 contain, titanium oxide, Ti02. Comparing Examples 2 and 4, it is possible to demonstrate the beneficial role of this oxide in the resistance to temperature, but also in the resistance to corrosion by acid, since the latter is improved despite the high content of A1203 and the lower Si02 content of Example 4.

The properties of resistance to temperature and acid corrosion, and the fibrous properties of the glasses according to the invention, are therefore particularly well optimized.

Claims (10)

RE IV INDI CAC I ONES

1. Fiberglass, characterized in that its composition comprises the following constituents in the limits defined below, expressed as percentages by weight: Si02 59 to 63 A1203 10 to 16 CaO 1 6 to 23 MgO of 1 to less than 3. 2 Na20 + K20 + Li: 2O 0 to 2 Ti02 0 to 1 B203 0. 1 to less than 1. 8 Li20 0 to 0. 5 ZnO 0 to 1 MnO 0 to 1 F 0 to 0.

2. Fiberglass according to claim 1, formed from a glass melting obtained by melting a characterized item in which the item includes borax.

3. Fiberglass according to one of the preceding claims, characterized in that the content of Ti02 is greater than or equal to 0.5%.

4. Fiberglass according to claim 1 or 2, characterized in that the content of B203 is greater than or equal to 0.5%.

5. Fiberglass according to claim 4 / characterized in that, when the content of TiO2 is less than or equal to 0.5%, the content of Si02 is greater than 60.5%.

6. Fiberglass according to one of the preceding claims, characterized in that the MgO content is greater than or equal to 2.2%.

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 a 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 per weight: Si02 59 to 63 A1203 10 to 16 CaO 16 to 23 MgO from 1 to less than 3.2 Na20 + K20 + Li20 0 to 2 Ti02 0 to 1 B203 0.1 to less than 1.8 Li20 0 to 0.5 ZnO '0 to 1 MnO 0 to 1 F 0 to 0.5

10. Process for manufacturing glass fibers, comprising 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 orifices placed in the base of one or more bushings, and assembly of the filaments in one or more fibers that are collected in a mobile support, the molten glass that feeds the bushings having a composition according to claim 9.