Method for producing glass fibres from glass bottle cullet

Abstract

The invention relates to a method for producing glass fibres having a target composition, the method comprising melting a mixture of raw materials to form a melt pool, wherein the bottle cullet represents more than 50%, in particular at least 62%, by weight of the molten glass obtained from the mixture of raw materials.

Description

Description Title: PROCESS FOR MANUFACTURING GLASS FIBERS FROM BOTTLE GLASS CULCATE

[0001] The invention relates to the field of melting a mixture of raw materials, in particular for the manufacture of glass wool as used especially in the field of thermal and / or acoustic insulation of buildings or other.

[0002] The manufacture of glass wool, particularly by the company that filed the application, through the melting and fiberization of abundant natural or synthetic raw materials (sand or volcanic rock), is a process that has been known and mastered for a long time. The resulting insulating products take the form, for example, of a glass wool "mattress" composed of a structure ranging from flexible to rigid, trapping air in a stable and immobile manner within the interlocking fibers.

[0003] Glass wool possesses excellent thermal and acoustic properties, making it a preferred material for insulating residential and non-residential buildings (commercial, industrial, and office buildings), as well as for use in the naval and nuclear sectors for over 80 years. Glass wool is available in a variety of forms: rolls, flexible or semi-rigid roll-out panels, rigid panels, batts, blankets, or loose fill.

[0004] Thanks to its intricate structure, which creates a multitude of small cavities, glass wool is a porous material that traps air. The still air trapped in these pores gives glass wool a high insulating capacity with a minimum of material.

[0005] The fiber is spun by centrifugation through perforated plates. The molten material passes through a spinneret and then through continuous spinning plates, emerging as glass fibers that are sprayed with polymer (the binder) to form a mat. After the addition of binders and other elements specific to each application, the wool mat is polymerized and calendered.

[0006] In addition to the criteria of quality and industrial and economic feasibility, the biosoluble nature of glass wool has been added in recent years, meaning its ability to dissolve rapidly in a physiological environment, in order to prevent any potential pathogenic risk linked to the possible accumulation of the finest fibers in the body through inhalation. A glass wool composition adapted accordingly was proposed in application EP399320, to which reference should be made for further details.

[0007] The choice of raw materials is crucial for obtaining high-quality glass, especially after fiberization. In particular, for the manufacture of glass wool, natural, secondary, and / or synthetic raw materials are used today.

[0008] These mineral materials can be mixed with cullet, particularly from flat glass. Cullet is produced from glass recycling and has the advantage of reducing the energy required to melt the glass.

[0009] Flat glass cullet, due to its oxide composition, is ideal for forming part of the molten pool, notably by providing all or part of the silicon, sodium, calcium, and magnesium oxides that make up the final glass fiber. Thus, flat glass cullet has oxide percentages relatively close to those of the glass fiber used in the insulating materials described previously.

[0010] Flat glass cullet is in high demand within the flat glass industry itself, as it is the only type of cullet that can be used in its furnaces. Bottle cullet cannot be used to supply flat glass plants, or only in very limited quantities, primarily due to differences in composition and color. Consequently, there is a strong demand for flat glass cullet within the flat glass industry, which limits its availability as a raw material for manufacturing other glass compositions, such as those used in the production of insulation wool.

[0011] Bottle cullet has a different composition than flat glass, which does not allow its use in large quantities in the manufacture of flat glass.

[0012] US patent application US2009 / 0120132 describes a different glass fiber composition in which 50% glass cullet is used. Tests conducted by the applicant company showed that the fiber-making process became very difficult for such a glass composition if quantities exceeding 50% bottle cullet were used as raw material for the melt.

[0013] One of the objects of the present invention is precisely to enable its valorization through its use in large quantities in a mineral wool manufacturing process.

[0014] A typical composition of bottle cullet glass is given below, in weight percentages: SiO2: between 70 and 75%, Na2O: between 12 and 15%, preferably between 12.5 and 14%, CaO: between 9 and 13%, preferably between 10 and 11%, MgO: between 0.5 and 4%, preferably between 1 and 2%, CaO + MgO together representing preferably between 9.5 and 15%, Al2O3: between 0.5 and 3%, preferably between 1 and 2%, K2O: between 0 and 2%, preferably between 0 and 1% Na2U and K2O together preferably representing between 12 and 15%, Fe2U3: between 0.01 and 3%, preferably less than 2%, preferably even less than 1%, other oxide(s): between 0 and 5% by weight cumulatively, preferably less than 3% cumulatively.

[0015] The chemical composition of bottle cullet (also described above) is further from that of the target insulating glass than that of flat glass cullet.

[0016] A typical composition of flat glass is given below: SiU2: between 69 and 75%, Na2U: between 10 and 16%, CaO: between 5 and 14%, MgO: between 0 and 6%, (2 to 5% in the automotive sector) Al2O3: between 0 and 3%, K2O: between 0 and 2%, other oxide(s): between 0 and 5% cumulatively.

[0017] A typical composition of glass fibers for insulating materials is given below: SiU2: between 60% and 75%, Na2U: between 10% and 25%, CaO: between 5% and 15%, MgO: between 1% and 10%, CaO and MgO together preferably represent between 5 and 20%, and the CaO / MgO ratio is less than 6.5 B2O3: between 0 and 10%, Al2O3: between 0 and 5%, preferably between 1 and 4%, K2O: between 0 and 5%, preferably between 0.2 and 2%, Na2O and K2O together preferably between 12 and 20%, other oxide(s): between 0 and 5% cumulative weight.

[0018] Such differences explain why, until now, relatively limited quantities of bottle cullet can be used for the manufacture of glass fiber for insulating materials. In particular, the CaO / MgO ratio is generally very different (greater than 6.5, even greater than 8, or even greater than 10 for bottle cullet and less than 6.5 for the target glass fiber composition), most often due to a lower MgO content in bottle cullet.

[0019] This chemical target deviation has the particular consequence of increasing the liquidus temperature Tn q The glassmaking process requires increasing the temperature of the molten glass in the fiber-forming plates to prevent the formation of crystals that disrupt the glass shaping process. This temperature increase results in additional energy costs and reduces the lifespan of the plates and / or the quality of the final product.

[0020] The fundamental properties used for fused glass compositions useful for fiberglass lamination are described below: - the temperature corresponding to a viscosity of 10 3 poises, denoted "Tlog3" and expressed in degrees Celsius, corresponding to the fiber-laying temperature, - the liquidus temperature, denoted "Tn q » or Tiiquidus, corresponding to the temperature below which the first crystals form.

[0021] As is well known, the forming margin, that is, the manufacturing margin by fiber stretching, can be achieved within a temperature range corresponding to the difference between Tlog3 and Tliq, denoted "AT" and expressed in degrees Celsius. In other words, if the glass temperature drops below Tliq during its passage through the fiber forming tools, particularly in the perforated plate, there is a risk of the calibrated holes in this part becoming clogged due to crystallization.

[0022] The use of bottle cullet in large quantities for the manufacture of glass fibers for insulation, in particular for more than 50%, or even more than 54%, or even more than 60%, or even more than 62% or even more than 65% of the mass of the molten glass enabling said manufacture is the object of the present invention.

[0023] The object of the present invention is in particular to provide a composition of glass, reagents and a process which allows the use of a very large quantity of bottle cullet without risking clogging problems of fiber-making instruments by early crystallization of the molten glass in them if the Tliq is too high.

[0024] This application was made possible according to the invention by adapting, on the one hand, the composition of the target glass and, on the other hand, by selecting the raw materials used in the melting bath, so as to introduce a large quantity of bottle cullet into the melting bath. In particular, thanks to this dual selection, it is possible to limit the liquidus temperature of the molten mixture to values ​​below 910°C, the maximum permissible temperature, in order to preserve the quality of the final product and the industrial equipment for fiberizing glass wool, especially the fiberizing plates and baskets currently in use. Furthermore, this dual selection makes it possible to significantly increase the AT range for manufacturing glass fibers.

[0025] According to the invention, it has been found that it is possible to maintain the liquidus temperature of a mixture of raw materials very rich in bottle cullet at temperatures less than or equal to 910°C both by specifically adapting the composition of the molten glass and by selecting in the vitrifiable mixture the raw materials sources of the element magnesium from the list described below.

[0026] More specifically, the present invention relates to a method for manufacturing glass fibers having a target composition, comprising melting a mixture of raw materials constituting a melting bath, said target composition having the following formulation, in weight percentage: - SiÛ2: more than 60% and up to 75%, preferably between 60 and 70%, - Na2O: between 10 and 25%, preferably between 10 and 20% - CaO: between 5 and 15%, preferably between 5 and 10% - MgO: between 1 and 10%, preferably between 2 and 5% - CaO and MgO together preferably representing between 5 and 20%, particularly between 6 and 20%, - B2O3: between 0.5 and 10%, preferably between 1 and 8%, preferably even more between 2 and 7%, - AI2O3: between 0 and 5%, preferably between 1 and 4% - K2O: between 0 and 5%, preferably between 0.2 and 2%, particularly between 0.5 and 1.5% - Na2U and K2O together preferably representing between 12 and 20% - Iron oxide: between 0 and 4%, in particular between 0 and 3%, preferably less than 2%, preferably even less than 1% - Manganese oxide: between 0 and 4%, in particular between 0 and 3%, preferably less than 2%, preferably even less than 1% - Phosphorus oxide, in particular P2O5: between 0 and 4%, in particular between 0 and 3%, preferably less than 2%, preferably even less than 1% - other oxide(s): between 0 and 5% cumulative weight, preferably less than 3% cumulative, - F2: less than 2%, preferably less than 1%, preferably not even of fluorine, the remainder being made up of unavoidable impurities, process in which said molten bath comprises as raw materials, in weight percentages: - bottle cullet, - at least one particular sodium source chosen from sodium hydroxide NaOH, sodium carbonate Na2COs or a mixture of sodium hydroxide NaOH and sodium carbonate Na2COs; - at least one source of magnesium, - optionally at least one source of calcium, - optionally a boron source, - optionally sources of phosphorus, manganese, iron and fluorine, said process being characterized in that: - said bottle cullet represents, by mass, more than 50%, preferably at least 62%, of the molten glass obtained from the mixture of raw materials constituting the melting bath, - the source(s) of B, Na, K, and possibly P and F (if present) are introduced into the raw material mixture in quantities such that the sum of the weight percentages of the oxides B2O3, Na2O, K2O, P2O5, F2 in said target composition is less than 25%, preferably less than 24%, - the source(s) of calcium and magnesium are introduced into the mixture of raw materials in quantities such that the CaO / MgO ratio in said target composition is less than 4.0.

[0027] According to particular and advantageous modes of the present invention, which can of course be combined with each other where appropriate:

[0028] • Said mixture includes a source of magnesium comprising at least 20% by weight of MgO,

[0029] • The molten mass obtained from said mixture has a difference between its Tlog3 and Tliq values ​​greater than 100°C, preferably greater than 110°C.

[0030] • MgO and SiC (if silicon is present in said magnesium source, in particular in the form of magnesium silicate), together represent more than 65%, preferably at least 70% of the total weight of the or a source of magnesium, and calcium oxide CaO represents less than 4% of the total weight of said source.

[0031] • Bottle cullet represents at least 60%, or even at least 62% of the mass of the molten glass obtained from the mixture of raw materials constituting the melting bath, or even at least 65% or even at least 70% of the mass of the molten glass obtained from the mixture of raw materials constituting the melting bath.

[0032] • A source of magnesium is a natural or synthetic mineral substance comprising, in weight percentages: - SiÛ2: between 40 and 55%, preferably between 45 and 50%, - AI2O3: between 0 and 12%, for example between 0.5 and 10% - MgO: between 20 and 60%, preferably between 25 and 40%, - MgO and SiU2 preferably representing in total at least 70%, or even at least 75%, of the weight of said source, - Fe2O3: between 0 and 4%, preferably between 1 and 3%, - less than 5% of other oxides, preferably less than 3% of other oxides, - possibly water, preferably in a quantity less than 20% and in particular between 5 and 15%.

[0033] • A source of magnesium is, at least in part, a natural mineral matter comprising, in weight percentages: - SiÛ2: between 55 and 70%, preferably between 58 and 65%, - AI2O3: between 0 and 12%, for example between 1 and 10% - MgO: between 20 and 40%, preferably between 25 and 35%, - MgO and SiU2 preferably representing a combined total of at least 85%, or even at least 90%, - Fe2Û3: between 0 and 4%, for example between 0.5 and 2%, - less than 5% of other oxides, preferably less than 3% of other oxides, - possibly water, preferably in a quantity less than 15% and in particular between 5 and 10%.

[0034] • A source of magnesium is, at least in part, a natural mineral substance meeting the following composition, in weight percentages: - SiÛ2: between 30 and 50%, preferably between 35 and 45%, - AI2O3: between 0 and 10%, for example between 1 and 5% - MgO: between 25 and 45%, preferably between 30 and 40%, - MgO and SiU2 preferably representing a combined total of at least 70%, or even at least 75%, - Fe2Û3: between 0 and 10%, for example between 5 and 10% - less than 5% of other oxides, preferably less than 3% of other oxides - possibly water, preferably in a quantity less than 20% and in particular between 5 and 15%.

[0035] • A source of magnesium is a natural or synthetic hydroxide mineral material, in particular of chemical formula Mg(OH)2, in particular brucite.

[0036] • A source of magnesium is a product derived from the recycling of refractory bricks with the following composition, expressed as a percentage by weight: - SiÛ2: between 0 and 5%, preferably between 0 and 1.5%, - AI2O3: between 0 and 10%, for example between 2 and 7% - MgO: between 70 and 99%, preferably between 80 and 95%, - MgO and SiU2 preferably representing a combined total of at least 70%, or even at least 75%, - Fe2O3: between 0 and 5%, preferably between 0 and 1% - less than 5% of other oxides, preferably less than 3% of other oxides.

[0037] • A source of magnesium is a mineral material comprising more than 90% magnesia in the form of magnesium oxide MgO, preferably more than 95% magnesia in the form of magnesium oxide MgO.

[0038] • Calcium is supplied essentially, if not exclusively, by bottle glass cullet.

[0039] • Recycled soda-lime silico-glass cullet and / or recycled mineral fibers, in particular recycled glass wool fibers, are introduced into the melt bath, the recycled soda-lime silico-glass cullet and / or recycled mineral fibers representing for example, but not limited to, between 1 and 40% of the total weight of the melt bath, preferably between 1 and 30% of the total weight of the melt bath.

[0040] • An additional source of calcium is introduced into the molten bath, preferably chosen from the group consisting of lime, for example quicklime or slaked limestone.

[0041] • The recycled glass fibers introduced into the melt bath have the following composition, in weight percentages: - SiÛ2: between 60 and 68%, preferably between 60 and 66%, - AI2O3: between 0 and 5%, for example between 1.5 and 4% - MgO: between 1 and 5%, preferably between 1.5 and 4%, - MgO and SiU2 preferably representing a combined total of at least 60%, or even at least 65%, - CaO: between 5 and 10%, preferably between 5 and 8%, - Fe2Û3: between 0 and 2%, for example between 0 and 1% - B2O3: between 0 and 10%, preferably between 2 and 8%, - Na2O: between 10 and 25%, preferably between 10 and 20%, - K2O: between 0 and 5%, preferably between 0.2 and 2%, - other oxides: less than 5% of other oxides, preferably less than 3% of other oxides.

[0042] • The mixture of raw materials includes a source of boron preferably chosen from a boron oxide such as boric acid or a mixed boron oxide with at least one element chosen from the group consisting of Si, Mg, Ca, Na in particular an oxide chosen from the group consisting of anhydrous or pentahydrated borax, natural or synthetic colemanite, ulexite possibly calcined, hydroboracite, razorite, tincal(conite) or kernite, and mixtures thereof.

[0043] • The final glass composition comprises more than 400 ppm of chromium oxide Cr20s, preferably more than 500 ppm of chromium oxide, preferably more than 700 ppm of chromium oxide.

[0044] The composition of some of these boron sources is described below for greater precision:

[0045] The mixture of raw materials includes an aluminum source selected from a mixed aluminum oxide with at least one element selected from the group consisting of Si, Ca, Na, K; in particular an aluminum silicate, and at least one element selected from Ca, Na or K; or hydrated alumina (Al(OH)3) or calcined Al2O3; or a feldspar of general composition (K,Na)AlSi3Os; or a phonolite, for example, of general composition 4SiO2.Al2O3.0.5(Na2O.K2O), or a nepheline, for example, of general composition 4SiO2.Al2O3.0.5(Na2O.K2O).

[0046] • The raw material mixture includes an additional silicon source, in particular selected from silica, glass cullet such as flat glass cullet, recycled mineral fibers, in particular recycled glass wool, in particular a mixture of silica and glass cullet or a mixture of silica and recycled mineral fibers, or a mixture of silica, flat glass cullet and recycled mineral fibers.

[0047] • In the final composition of the glass fibers obtained according to the invention, the content of chromium oxide C^Os is greater, in weight percentages, than 0.05% and preferably is greater than 0.06%, or even greater than or equal to 0.07%.

[0048] • In the final composition of the glass fibers obtained according to the invention, the mass content of manganese oxide MnO is between 0 and 3%, in particular between 0.05 and 1%.

[0049] • In the final composition of the glass fibers obtained according to the invention, the mass content of phosphorus oxide P2O5 is between 0 and 3%, for example between 0 and 2%, in particular between 0.05 and 1%.

[0050] The invention also relates to a mixture of raw materials as described above.

[0051] In particular, the invention relates to a mixture of raw materials for fiberglass spinning as described above, the target composition of which corresponds to the following formulation in oxides and weight percentage: - SiÛ2: more than 60% and up to 75%, preferably between 60 and 70% - Na2O: between 10 and 25%, preferably between 10 and 20% - CaO: between 5 and 15%, preferably between 5 and 10% - MgO: between 1 and 10%, preferably between 2 and 5% - CaO and MgO together preferably representing between 5 and 20% - B2O3: between 0.5 and 10%, preferably between 2 and 8% - AI2O3: between 0 and 5%, preferably between 1 and 4% - K2O: between 0 and 5%, preferably between 0.2 and 2% - Na2U and K2O together preferably representing between 12 and 20% - Iron oxide: between 0 and 4%, preferably less than 2%, preferably even less than 1% - other oxide(s): between 0 and 5% cumulative weight, preferably less than 3% cumulative, - F2: less than 2%, preferably less than 1%, preferably no fluorine, said mixture comprising: - bottle cullet, - at least one source of magnesium, - possibly at least one source of calcium, - at least one source of sodium preferably chosen from sodium hydroxide NaOH, sodium carbonate Na2COs or a mixture of sodium hydroxide NaOH and sodium carbonate Na2COs or a mixture thereof.

[0052] According to the invention, in said mixture: - said bottle cullet represents more than 50%, preferably at least 62%, of the mass of the molten glass obtained from the mixture of raw materials constituting the melting bath, - the source(s) of calcium and magnesium are introduced into the raw material mixture in quantities such that the CaO / MgO ratio in the final target composition is less than 4.0, - the source(s) of B, Na, K, and possibly P and F are introduced into the raw material mixture in quantities such that the sum of the weight percentages of the oxides B2O3, Na2O, K2O, P2O5, F2 in said target composition is less than 25%, preferably less at 24%, - preferably, said mixture includes a source of magnesium comprising at least 20% by weight of MgO.

[0053] In such a mixture, advantageously, the molten mass obtained from said mixture has a difference between its Tlog3 and Tliq values ​​greater than 100°C, preferably greater than 110°C.

[0054] According to a preferred method, in said mixture, said bottle cullet represents at least 60% of the mass of the molten glass obtained from the mixture of raw materials constituting the melting bath, or at least 65% of the mass of the molten glass from the mixture of raw materials.

[0055] Of course, the invention relates to all the other preferred characteristics of said mixture described previously in relation to the process of manufacturing glass fibers having said target composition, without it being necessary here to repeat all of these characteristics in detail.

[0056] Hydroxides (OH) are considered according to the present invention as oxides and as forming part of the chemical composition of the source, unlike free water (that is to say, present as moisture in the natural mineral matter).

[0057] The raw material mixture is heated until a molten bath is obtained, generally in a furnace. The heating temperature and duration vary depending on the desired quality of mineral fibers, particularly the tolerance level for unmelted particles. Generally, the initial mixture is heated to between 1200 and 1500°C for complete melting. The transformation of the raw material mixture can be carried out using melting techniques well-known to those skilled in the art. This transformation can be performed in any type of furnace, such as an electric electrode furnace, an induction furnace, an overhead burner furnace (including transverse burner furnaces), a loop furnace, a submerged burner furnace, or a combination of these heating methods.

[0058] For heating and melting, the mixture of raw materials, possibly moistened, can be introduced into a furnace in a powdered state, which This implies that each raw material it contains is in powder form or in the form of briquettes or granules, with the introduction taking place in one or more stages. For heating and melting, the mixture of raw materials, possibly moistened, can be introduced into a furnace in a composition comprising cullet and the mixture of raw materials, the latter possibly being powdery.

[0059] The following examples, given purely for illustrative purposes, show the advantages obtained by application of the present invention. Examples:

[0060] We prepare different mixtures of raw materials in order to compare a mixture such as that currently used for the manufacture of glass wool to obtain a glass of substantially identical composition, which has substantially the following formulation in weight percentage of oxides: [Table 1]

[0061] Glass compositions meeting the above formulation are synthesized using current techniques, following these steps: - The raw materials for the said melting bath are selected from the list of raw materials described below, - the necessary quantities of said raw materials are determined to obtain a glass of said target composition, - the mixture of said materials is carried out according to said quantities, - the said mixture is melted and cooled under conditions allowing the said glass to be obtained in the form of fibers after fibering.

[0062] The mixture of raw materials is introduced hot into a platinum crucible in a flame furnace (air-gas or oxy-gas combustion) at 1450°C until the mixture is completely melted for a total duration of 3h15 including 120 min of refining.

[0063] The raw materials used are as follows: [Table 2]

[0064] The bottle cullet used has the following formulation: SiO2: 72.5%, Na2O: 12.7%, CaO: 11.3% MgO: 1% AI2O3: 1.5% K2O: 0.6% Fe2O3: 0.1% others: 0.3%.

[0065] Table 3 below shows the composition of the final glass obtained, and the weight percentages of the different raw materials used. and the liquid temperature of the mixture and the temperature Tlog3, at which the glass has a viscosity of 10 3 Poise. [Table 3] comparative examples ** fluxes: B2O3, Na20, K2O, P2O5, F2 *** hydrated alumina

[0066] The comparative mixtures of examples 1 and 2 show that it is possible to perform fiberization of the given glass composition in the Table 1 shows no risk for glass cullet introduction rates up to 50% by mass, as the liquidus temperature Tliq remains sufficiently low to allow the fiber-binding process to be carried out under acceptable conditions. Conversely, when the bottle cullet introduction rate exceeds 50%, a significant increase in the liquidus temperature Tn is observed. q of the mixture of raw materials and a significant decrease in the AT fiber-making temperature range.

[0067] The mixtures of examples 4, 6, 8, 10 and 12 conform to the present invention: they comprise more than 50% by mass of bottle cullet as raw material and the composition of the target glass is adjusted in accordance with the subject matter of the present claims, in particular the silica content, the CaO / MgO ratio and by the use of talcite as a source of magnesium.

[0068] Comparative examples 3, 5, 7, 9 and 11 have the same percentages of glass cullet introduction into the glass as examples 4, 6, 8, 10 and 12 respectively, but differ in the CaO / MgO ratio and the use of dolomite as a source of magnesium.

[0069] Example 13, outside the scope of the invention and in accordance with US2009 / 0120132, includes an excessively high flux content in the choice of raw materials as well as a target glass composition comprising too low a quantity of SiC and a large quantity of ALOs.

[0070] We can see from the data in Table 3 that the use of bottle cullet percentages above 50% results in a sharp increase in the Tliq temperature described previously for all examples.

[0071] Comparison of the examples shows that, for the same bottle cullet introduction rate, the liquidus temperature is significantly reduced for the melting baths according to the invention, in which the composition of the target glass and the choice of raw materials are adjusted as described in the following claims. In particular, the data reported in the preceding table show that the liquidus temperature of examples 4, 6, 8, 10, and 12 according to the invention, in which the mass percentage of bottle cullet is greater than 55%, 60%, up to 85%, remains significantly lower than that of comparative examples 2, 3, 5, 7, 9, and 11, which have the same percentages of bottle cullet introduced into the initial reagent mixture. The liquidus temperatures obtained for the mixtures according to the invention are all below 910°C and are even close to those of reference examples 1 and 2, which contain only 40% and 50% by mass of bottle cullet, respectively. Conversely, the liquidus temperatures of the comparative examples using a large quantity of bottle cullet show a sharp increase.

[0072] Similarly, the value of the AT forming interval is considerably increased in the case of the examples according to the invention, whereas it decreases sharply for the comparative examples.

[0073] The data grouped in Table 3 above show that Example 13, which is outside the invention and conforms to the prior art, is characterized by a significant decrease in the value of the AT interval, as well as a Tliq that is too high (925 °C), which makes the fiber-making process very difficult to implement.

[0074] It is observed that the chromium oxide (Cr2O3) content increases proportionally with the percentage of bottle cullet used in the melt. A 10% increase in bottle cullet corresponds to an increase of approximately 100 ppm to 200 ppm in the chromium oxide content of the final glass.

Claims

DEMANDS 1. A process for manufacturing glass fibers having a target composition, comprising melting a mixture of raw materials constituting a melt bath, said target composition having the following formulation in oxides, by weight percentage: - SiÛ2: more than 60% and up to 75%, preferably between 60 and 70% - Na2O: between 10 and 25%, preferably between 10 and 20% - CaO: between 5 and 15%, preferably between 5 and 10% - MgO: between 1 and 10%, preferably between 2 and 5% - CaO and MgO together preferably representing between 5 and 20% - B2O3: between 0.5 and 10%, preferably between 1 and 8% - AI2O3: between 0 and 5%, preferably between 1 and 4% - K2O: between 0 and 5%, preferably between 0.2 and 2% - Na2U and K2O together preferably representing between 12 and 20% - Iron oxide: between 0 and 4%, preferably less than 2%, preferably even less than 1% - Manganese oxide: between 0 and 4%, in particular between 0 and 3%, preferably less than 2%, preferably even less than 1% - Phosphorus oxide, in particular P2O5: between 0 and 4%, in particular between 0 and 3%, preferably less than 2%, preferably even less than 1% - other oxide(s): between 0 and 5% cumulative weight, preferably less than 3% cumulative, - F2: less than 2%, preferably less than 1%, preferably no fluorine, the remainder being unavoidable impurities, said molten bath comprising: - bottle cullet, - at least one source of sodium preferably chosen from sodium hydroxide NaOH, sodium carbonate Na2COs or a mixture of sodium hydroxide NaOH and sodium carbonate Na2COs; - at least one source of magnesium, - optionally at least one source of calcium, - optionally sources of boron B, phosphorus P, manganese Mn, iron Fe and fluorine F, said process being characterized in that: said bottle cullet represents, by mass, at least 62% of the molten glass obtained from the mixture of raw materials constituting the melting bath, - the quantities of the sources of Na, B, K, and possibly P and F are introduced into the mixture in such a way that the sum of the weight percentages of the oxides B2O3, Na2O, K2O, P2O5, F2 in said target composition is less than 25%, preferably less than 24%, - the quantities of the source(s) of calcium and magnesium are introduced into the mixture of raw materials in quantities such that the CaO / MgO ratio in said target composition is less than 4.

0.

2. A method for manufacturing glass fibers according to claim 1, wherein said mixture comprises a magnesium source comprising at least 20% by weight of MgO, 3. A method for manufacturing glass fibers according to claim 1 or 2, wherein the molten mass obtained from said mixture exhibits a difference AT between its Tlog3 and Tliq values ​​greater than 100°C, preferably greater than 110°C, Tlog3 being the temperature corresponding to a viscosity of 10 3 poises of the molten mixture and Tliq being the temperature below which the first crystals form from the molten mixture.

4. A method for manufacturing glass fibers according to any one of the preceding claims, wherein MgO and SiU2 together represent more than 65%, preferably at least 70% of the total weight of one or more of the magnesium source, and calcium oxide CaO represents less than 4% of the total weight of said source.

5. A method for manufacturing glass fibers according to any one of the preceding claims, wherein a source of magnesium is a natural or synthetic mineral material comprising, in weight percentages: - SiÛ2: between 40 and 55%, preferably between 45 and 50%, - AI2O3: between 0 and 12%, for example between 0.5 and 10% - MgO: between 20 and 40%, preferably between 25 and 35%, MgO and SiO2, preferably representing in combination at least 70%, or even at least 75%, of the weight of said source, - Fe2Û3: between 0 and 4%, for example between 1 and 3% - less than 5% of other oxides, preferably less than 3% of other oxides - possibly water, preferably in a quantity less than 20% and in particular between 5 and 15%.

6. A method for manufacturing glass fibers according to any one of the preceding claims, wherein a source of magnesium is a natural or synthetic mineral material comprising, in weight percentages: - SiÛ2: between 55 and 70%, preferably between 58 and 65%, - AI2O3: between 0 and 12%, for example between 1 and 10% - MgO: between 20 and 40%, preferably between 25 and 35%, - MgO and SiU2 preferably representing a combined total of at least 85%, or even at least 90%, - Fe2Û3: between 0 and 4%, for example between 0.5 and 2%, - less than 5% of other oxides, preferably less than 3% of other oxides, - possibly water, preferably in a quantity less than 15% and in particular between 5 and 10%.

7. A method for manufacturing glass fibers according to any one of the preceding claims, wherein a source of magnesium is a natural or synthetic mineral material comprising, in weight percentages: - SiÛ2: between 30 and 50%, preferably between 35 and 45%, - AI2O3: between 0 and 10%, for example between 1 and 5% - MgO: between 25 and 45%, preferably between 30 and 40%, - MgO and SiU2 preferably representing a combined total of at least 70%, or even at least 75%, - Fe2Û3: between 0 and 10%, for example between 5 and 10% - less than 5% of other oxides, preferably less than 3% of other oxides - possibly water, preferably in a quantity less than 20% and in particular between 5 and 15%.

8. A process for manufacturing glass fibers according to any one of the preceding claims, wherein a source of magnesium is a product obtained from the recycling of refractory bricks having in particular the following composition, in weight percentages: - SiÛ2: between 0 and 5%, preferably between 0 and 1.5%, - AI2O3: between 0 and 10%, for example between 2 and 7% - MgO: between 70 and 99%, preferably between 80 and 95%, - MgO and SiU2 preferably representing a combined total of at least 70%, or even at least 75%, - Fe2O3: between 0 and 5%, preferably between 0 and 1% - less than 5% of other oxides, preferably less than 3% of other oxides.

9. A method for manufacturing glass fibers according to any one of the preceding claims, wherein a source of magnesium is a natural or synthetic mineral hydroxide, in particular of chemical formula Mg(OH)2, in particular brucite.

10. A method for manufacturing glass fibers according to any one of the preceding claims, wherein a source of magnesium is a natural or synthetic mineral material comprising more than 90% magnesia in the form of magnesium oxide MgO, preferably more than 95% magnesia in the form of magnesium oxide MgO.

11. A method for manufacturing glass fibers according to any one of the preceding claims, wherein the mixture of raw materials further comprises a silicon source, in particular selected from silica, flat glass cullet, recycled mineral fibers, in particular recycled glass wool, in particular a mixture of silica and flat glass cullet or a mixture of silica and recycled mineral fibers, or a mixture of silica, flat glass cullet and recycled mineral fibers.

12. A method for manufacturing glass fibers according to any one of the preceding claims, wherein recycled glass cullet and / or recycled mineral fibers, in particular recycled glass wool fibers, recycled glass cullet and / or recycled mineral fibers, preferably representing between 1 and 40% of the total weight of the melt bath, are further introduced into the melt bath.

13. A process for manufacturing glass fibers according to any one of the preceding claims, wherein the mixture of raw materials further comprises a source of boron preferably selected from a boron oxide such as boric acid or a mixed boron oxide with at least one element selected from the group consisting of Si, Mg, Ca, Na, in particular an oxide selected from the group consisting of anhydrous or pentahydrated borax, natural or synthetic colemanite, ulexite optionally calcined, hydroboracite, razorite, tincal(conite) or kernite, and mixtures thereof.

14. A method for manufacturing glass fibers according to any one of the preceding claims, wherein the mixture of raw materials further comprises an aluminum source selected from a mixed aluminum oxide with at least one element selected from the group consisting of Si, Ca, Na, K, in particular an aluminum silicate and at least one element selected from Ca, Na or K, or hydrated alumina (Al(OH)3) or calcined Al2O3, a feldspar of general composition (K,Na)AlSi3Os or a phonolite for example of general composition 4SiO2.Al2O3.Q,5(Na2O.K2O) or a nepheline for example of general composition 4SiO2.Al2O3.0,5(Na2O.K2O).

15. A process for manufacturing glass fibers according to any one of the preceding claims, wherein the mixture of raw materials further comprises a source of calcium preferably selected from the group consisting of lime, for example quicklime or slaked lime, or limestone.

16. A method for manufacturing glass fibers according to any one of the preceding claims, wherein said bottle cullet represents at least 65% of the mass of the glass obtained from the mixture of raw materials constituting the melting bath.

17. A process for manufacturing glass fibers according to any one of the preceding claims, wherein the final glass composition comprises more than 400 ppm of chromium oxide Cr2O3, preferably more than 500 ppm of chromium oxide, preferably more than 700 ppm of chromium oxide.

18. Mixture of raw materials as described above for fiberglass fiber production, the target composition of which corresponds to the following formulation in oxides and weight percentage: - SiÛ2: more than 60% and up to 75%, preferably between 60 and 70% - Na2O: between 10 and 25%, preferably between 10 and 20% - CaO: between 5 and 15%, preferably between 5 and 10% - MgO: between 1 and 10%, preferably between 2 and 5% - CaO and MgO together preferably representing between 5 and 20% - B2O3: between 0.5 and 10%, preferably between 1 and 8% - AI2O3: between 0 and 5%, preferably between 1 and 4% - K2O: between 0 and 5%, preferably between 0.2 and 2% - Na2U and K2O together preferably representing between 12 and 20% - Iron oxide: between 0 and 4%, preferably less than 2%, preferably even less than 1% - other oxide(s): between 0 and 5% cumulative weight, preferably less than 3% cumulative, - Manganese oxide: between 0 and 4%, in particular between 0 and 3%, preferably less than 2%, preferably even less than 1% - Phosphorus oxide, in particular P2O5: between 0 and 4%, in particular between 0 and 3%, preferably less than 2%, preferably even less than 1% - F2: less than 2%, preferably less than 1%, preferably no fluorine, said mixture comprising: - bottle cullet, - at least one source of magnesium, - possibly at least one source of calcium, - at least one source of sodium, preferably chosen from sodium hydroxide (NaOH), sodium carbonate (Na2COs), or a mixture of sodium hydroxide NaOH and sodium carbonate Na2CÛ3 or a mixture thereof, - optionally at least one source of calcium, - optionally sources of boron B, phosphorus P, manganese Mn, iron Fe and fluorine F, said mixture being characterized in that: - said bottle cullet represents at least 62% of the mass of the molten glass obtained from the mixture of raw materials constituting the melting bath, - the source(s) of calcium and magnesium are introduced into the raw material mixture in quantities such that the CaO / MgO ratio in the final target composition is less than 4.0, - the source(s) of B, Na, K, and possibly P and F are introduced into the raw material mixture in quantities such that the sum of the weight percentages of the oxides B2O3, Na2O, K2O, P2O5, F2 in said target composition is less than 25%, preferably less than 24%, 19. Mixture according to the preceding claim, wherein said mixture comprises a magnesium source comprising at least 20% by weight of MgO.

20. Mixture of raw materials according to claim 18 or 19 in which the molten mass obtained from said mixture has a difference between its Tlog3 and Tliq values ​​greater than 100°C, preferably greater than 110°C.

21. Mixture of raw materials according to claim 18 to 20 wherein said bottle cullet represents more than 65% of the mass of the glass obtained from the mixture of raw materials constituting the melting bath.

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