PROCESS FOR MANUFACTURING GLASS FIBERS FROM BOTTLE GLASS CULCATE

Abstract

A process for manufacturing glass fibers having a target composition, comprising melting a mixture of raw materials constituting a melt pool, in which bottle cullet represents, by mass, more than 50% of the molten glass obtained from said mixture of raw materials.

Description

Title of the invention: METHOD 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, particularly by the applicant company, of glass wool by melting and fiberizing abundant natural or synthetic raw materials (sand or volcanic rock) is a process that has been known and mastered for a long time. The insulating products thus obtained take the form, for example, of a glass wool "mattress" composed of a structure varying from flexible to rigid and trapping air in a stable and immobile manner within the interlocking fibers.

[0003] Glass wool possesses excellent thermal and acoustic properties, which have made 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 marketed in a variety of forms: rolls, flexible or semi-rigid unrolled panels, rigid panels, shells, blankets, or loose fill.

[0004] Thanks to its interlocking structure generating 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 produced by centrifugation through perforated plates. The molten material passes through a die and then through continuous fiber-forming plates, from which it emerges 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 use, the wool mat is polymerized and calendered.

[0006] In recent years, in addition to the criteria of quality and industrial and economic feasibility, the biosoluble nature of glass wool has been added to the list of requirements. This refers to 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 essential to obtain good quality glass, particularly after fiberization. In particular, for the manufacture of glass wool, Today we use natural raw materials, secondary and / or synthetic materials.

[0008] These mineral materials can be mixed with cullet, in particular 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 is ideal, due to its oxide composition, for forming part of the melt 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 above.

[0010] Flat glass cullet is, however, in high demand by the flat glass industry itself, as it can only use this type of cullet in its furnaces. It is impossible to use bottle cullet to supply flat glass plants, or only in very limited quantities, particularly due to the difference in composition and color of bottle cullet. There is therefore a strong demand for flat glass cullet within the flat glass industry, which limits its availability as a raw material for the manufacture of other glass compositions, such as that used in the production of insulation wool.

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

[0012] US patent application 2009 / 0120132 describes a different glass fiber composition in which 50% glass cullet is used. Tests carried out by the applicant company showed that the fiber-making process became very difficult for such a glass composition if quantities exceeding 50% of bottle cullet are used as raw material for the melt bath.

[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 preferably between 9.5 and 15%, Al2O3: between 0.5 and 3%, preferably between 1 and 2% K20: between 0 and 2%, preferably between 0 and 1% Na2O and K2O together preferably representing between 12 and 15%, Fe2O3: between 0.01 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.

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

[0016] A typical composition of flat glass is given below: SiO2: between 69 and 75%, Na2O: 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 glass fiber composition for insulating materials is given below: SiO2: between 60% and 75%, Na2O: 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, or 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 the bottle cullet.

[0019] This chemical target deviation has the particular consequence of increasing the liquidus temperature Tiiq of the glass produced, which necessitates increasing the The temperatures of the molten glass in the fiber-forming plates are adjusted to avoid 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 103 poises, noted "Tlog3" and expressed in degrees Celsius, corresponding to the fiber-forming temperature, - the liquidus temperature, noted "TUq" or Tiiquidus, corresponding to the temperature below which the first crystals form.

[0021] As is well known, the forming margin, i.e., the manufacturing margin by fiber stretching, can be carried out 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 falls below Tliq during its passage through the fiber forming tools, particularly in the perforated plate, there is a risk of clogging the calibrated holes in this part 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 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 use 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, in particular the fiberizing plates and baskets currently in use. Furthermore, said 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 raw material mixture very rich in bottle cullet at temperatures less than or equal to 910°C by specifically adapting the composition of the molten glass and by selecting in the vitrifiable mixture the raw materials sources of the element magnesium in 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 melt bath, said target composition having the following formulation, in weight percentage: - SiO2: 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%, - Al2O3: 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% - Na2O 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 no fluorine at all, the remainder being unavoidable impurities, process in which said melting bath comprises, as raw materials, in weight percentages: - bottle cullet, - at least one particular sodium source chosen from sodium hydroxide NaOH, sodium carbonate Na2CO3 or a mixture of sodium hydroxide NaOH and sodium carbonate Na2CO3; - 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% 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 mixture of raw materials 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.

[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 comprises a source of magnesium comprising at least 20% weight of MgO

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

[0030] • MgO and SiO2 (if silicon is present in said magnesium source, particularly 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] • The bottle cullet represents at least 60%, or even at least 62% of the mass molten glass obtained from the mixture of raw materials constituting the melting bath, or 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 material including, as percentages by weight: - SiO2: between 40 and 55%, preferably between 45 and 50%, - Al₂O₃: between 0 and 12%, for example between 0.5 and 10% - MgO: between 20 and 60%, preferably between 25 and 40%, - MgO and SiO2 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 including, as percentages by weight: - SiO2: between 55 and 70%, preferably between 58 and 65%, - A12O3: between 0 and 12%, for example between 1 and 10% - MgO: between 20 and 40%, preferably between 25 and 35%, - MgO and SiO2, preferably representing a combined total of at least 85%, or even at least 90%, - Fe2O3: 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 matter corresponding to the following composition, in weight percentages: - SiO2: between 30 and 50%, preferably between 35 and 45%, - Al2O3: between 0 and 10%, for example between 1 and 5% - MgO: between 25 and 45%, preferably between 30 and 40%, - MgO and SiO2, preferably representing a combined total of at least 70%, or even at least 75%, - Fe2O3: 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 an amount less than 20% and in particular between 5 and 15%.

[0035] • A source of magnesium is a natural mineral hydroxide or synthetic, 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 composition, expressed as a percentage by weight: - SiO2: between 0 and 5%, preferably between 0 and 1.5%, - A12O3: between 0 and 10%, for example between 2 and 7% - MgO: between 70 and 99%, preferably between 80 and 95%, - MgO and SiO2, 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 matter comprising more than 90% of 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 or even solely by glass cullet bottle,

[0039] • Recycled soda-lime silico-glass cullet is introduced into the melting bath and / or recycled mineral fibers, in particular recycled glass wool fibers, 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 pool, preferably between 1 and 30% of the total weight of the melt pool.

[0040] • An additional source of calcium is introduced into the melting bath, preference 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 composition The following, expressed as weight percentages: - SiO2: between 60 and 68%, preferably between 60 and 66%, - A12O3: between 0 and 5%, for example between 1.5 and 4% - MgO: between 1 and 5%, preferably between 1.5 and 4%, - MgO and SiO2, preferably representing a combined total of at least 60%, or even at least 65%, - CaO: between 5 and 10%, preferably between 5 and 8%, - Fe2O3: 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 raw material mixture comprises 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 Cr2 O3, preferably more than 500 ppm chromium oxide, preferably more than 700 ppm chromium oxide.

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

[0045] The raw material mixture 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 (Al₂(OH)₃) or calcined alumina Al₂O₃; or a feldspar with general composition (K,Na)AlSi3O8; or a phonolite for example with general composition 4SiO2.Al2O3.0.5(Na2O.K2O), or a nepheline for example with general composition 4SiO2.Al2O3.0.5(Na2O.K2O).

[0046] • The raw material mixture includes an additional silicon source in particular chosen 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 in chromium oxide Cr2O3 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 content the mass percentage of manganese oxide MnO is between 0 and 3%, specifically between 0.05 and 1%.

[0049] • In the final composition of the glass fibers obtained according to the invention, the content the mass percentage 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: - SiO2: 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% - 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 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 with no fluorine at all. said mixture comprising: - bottle cullet, - at least one source of magnesium, - optionally at least one source of calcium, - at least one source of sodium preferably chosen from sodium hydroxide NaOH, sodium carbonate Na2CO3 or a mixture of sodium hydroxide NaOH and sodium carbonate Na2CO3 or a mixture thereof.

[0052] According to the invention, in said mixture: - said bottle cullet represents more than 50% 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, - 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%, - 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 mode, 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 even 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 above 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 (i.e. present in the form of moisture in the natural mineral matter).

[0057] The mixture of raw materials is heated until a molten bath is obtained, generally in a furnace. The heating is carried out to a greater or lesser temperature and for a greater or lesser duration depending on the quality of mineral fibers that are sought, in particular depending on the degree of tolerance for unmelted particles (called "unmelted"). Generally, the heating temperature of the initial mixture is between 1200 and 1500°C for complete melting. For processing the raw material mixture, well-known melting techniques can be used. This processing can be carried out in any type of furnace, such as an electric electrode furnace, an induction furnace, an overhead burner furnace, a transverse burner furnace, a loop furnace, a submerged burner furnace, or a combination of these heating methods.

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

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

[0060] Different mixtures of raw materials are prepared 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:

[0061] [Tables 1] Elements Percentage by weight % SiO2 65-66 CaO 6-9 B2O3 5.0 Na2O 16-17 MgO 1.5-3.5 CaO+MgO 9-12 Al2O3 2.1 Fe2O3 <0.5 k2O <1 Other oxygen impurities

[0062] Glass compositions conforming to the preceding formulation are synthesized according to 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 said materials are mixed according to the 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.

[0063] 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 3hl5 including 120 min of refining.

[0064] The raw materials used are as follows:

[0065] [Tables2] Name Formula Sand SiO2 Feldspar (Na,K)AlSi3O8 Sodium carbonate Na2CO3 Dolomite CaMg(CO3)2 Borax Na2B4O7-5H2O Limestone CaCO3 Talcite Mg3Si4O10(OH)2 Recycled glass wool -

[0066] The bottle cullet used has the following formulation: SiO2: 72.5%, Na2O: 12.7%, CaO: 11.3%, MgO: 1%, Al2O3: 1.5% K2O: 0.6% Fe2O3: 0.1% other: 0.3%.

[0067] Table 3 below shows the composition of the final glass obtained, the weight percentages of the different raw materials used and the temperature of liquidas of the mixture and the temperature Tlog3, at which the glass has a viscosity of 103 Poise.

[0068] [Tables 3] Example 1* 2* 3* 4 5* 6 7* 8 9* 10 11* 12 13* Composition of the final glass fibers obtained (% by weight) %SiO2 65.7 65.5 65.3 65.3 65.1 65.0 65.5 65.3 65.0 65.4 62.2 63.8 58.0 %Al2O3 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 1.8 2.0 5.2 %Na2O 16.3 17.0 16.1 17.0 15.8 16.5 15.9 16.3 15.7 16.4 17.8 17.8 15.4%K2O 0.6 0.7 0.7 0.5 0.7 0.5 0.7 0.6 0.7 0.6 0.7 0.7 1.0%CaO 7.6 7.7 8.5 6.3 9.1 7.2 9.1 8.0 9.5 8.0 10.1 8.5 8.6%MgO 2.5 1.9 2.1 3.2 2.0 3.5 1.7 2.2 1.8 2.3 2.4 2.5 2.6%B2O3 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 8.0 %Fe2O3 0.1 0.1 0.2 0.2 0.1 0.2 0.1 0.2 0.1 0.1 0.3 0.4 - %Cr2O3 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 - f2 - 1.0 Sum of fluxes** 21.9 22.7 21.8 22.5 21.5 22.0 21.6 21.9 21.4 22.0 23.5 23.5 25.4 CaO / MgO 3.0 4.1 4.1 2.0 4.5 2.1 5.4 3.6 5.3 3.5 4.2 3.4 3.3 %impurities oxides <1.0 <1.0 0 <1, 0 <1, 0 <1, 0 <1, 0 <1, 0 <1, 0 <1, 0 <1, 0 <1, 0 <1, 0 <1,0 Weight of raw materials used in kg (per 1000 kg of glass obtained) Sand 303 230 201 192 146 132 97 94 99 96 0 0 93 Borax 102 102 102 102 102 102 102 102 102 102 102 163 Dolomite 104 100 39 0 68 0 40 0 ​​54 0 54 0 0 Sodium carbonate 146 120 111 130 89 104 70 78 72 86 77 77 65 Feldspar 88 79 74 34 67 22 49 30 60 36 20 15 58* ** Bottle cullet 400 500 550 550 630 630 630 630 700 700 850 850 630 Recycled glass wool 0 0 0 0 0 0 100 100 0 0 0 0 0 , Talcite 0 0 0 84 0 91 0 40 0 ​​50 0 37 63 %Cullet bottle in the mass of molten glass 40 50 55 55 63 63 63 63 70 70 85 85 63 TA liquidus 898 901 915 868 933 899 928 904 941 904 929 898 925 Tiog3 106 105 106 106 106 106 106 106 106 106 100 101 100 4 2 1 1 1 0 0 2 0 0 0 7 0 DT 166 151 146 200 127 161 132 158 119 156 71 119 75

[0069] * comparative examples

[0070] ** fluxes: B2O3, Na2O, K2O, P2O5, F2

[0071] * * * hydrated alumina

[0072] The comparative mixtures in Examples 1 and 2 show that it is possible to safely fiberize the glass composition given in Table 1 with glass cullet introduction rates of up to 50% by mass, as the liquidus temperature Tliq remains sufficiently low to allow the fiberizing process to be carried out under acceptable conditions. Conversely, when the bottle cullet introduction rate exceeds 50%, a significant increase in the liquidus temperature Tiiq of the raw material mixture and a significant decrease in the fiberizing temperature range DT are observed.

[0073] The mixtures of examples 4, 6, 8, 10 and 12 are in accordance with 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.

[0074] Comparative examples 3, 5, 7, 9 and 11 have the same percentages of introduction of glass cullet 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.

[0075] Example 13, outside the scope of this invention and in accordance with US2009 / 0120132, includes an excessively high flux rate in the choice of raw materials as well as a target glass composition comprising too little SiO2 and a large amount of Al2O3.

[0076] It can be seen from the data in Table 3 that the use of percentages of bottle cullet beyond 50% results in a sharp increase in the temperature Tliq described above for all examples.

[0077] 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%, and up to 85%, remains much lower than that of comparative examples 2, 3, 5, 7, 9, and 11, which have the same percentages of bottle cullet introduction 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. In contrast, the liquidus temperatures of the comparative examples using a large quantity of bottle cullet show a significant increase.

[0078] 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.

[0079] The data grouped in Table 3 above show that Example 13, which is outside the invention and in accordance with 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.

[0080] It is observed that the chromium oxide (Cr2O3) content increases proportionally with the percentage of bottle cullet used in the melt bath. A 10% increase in bottle cullet corresponds to an increase of approximately 100 ppm to 200 ppm in the chromium oxide content in the final glass.

Claims

1. Demands 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, in weight percentages: - SiO2: 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% - 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 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%, particularly between 0 to 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 with no fluorine at all. the remainder being made up of unavoidable impurities, said molten bath comprising: - bottle cullet, - at least one source of sodium preferably chosen from sodium hydroxide NaOH, sodium carbonate Na2CO3 or a mixture of sodium hydroxide NaOH and sodium carbonate Na2CO3; - 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, more than 50% 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 optionally 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.

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 has a difference DT between its Tlog3 and Tliq values ​​greater than 100°C, preferably greater than 110°C, Tlog3 being the temperature corresponding to a viscosity of 103 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 SiO2 together represent more than 65%, preferably at least 70% of the total weight of one or 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:

6.

7. - SiO2: between 40 and 55%, preferably between 45 and 50%, - Al₂O₃: 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, - Fe2O3: between 0 and 4%, for example between 1 and 3% - less than 5% of other oxides, preferably less than 3% other oxides - possibly water, preferably in a quantity less than 20% and in particular between 5 and 15%. A process 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: - SiO2: between 55 and 70%, preferably between 58 and 65%, - A12O3: between 0 and 12%, for example between 1 and 10% - MgO: between 20 and 40%, preferably between 25 and 35%, - MgO and SiO2, preferably representing a combined total of at least 85%, or even at least 90%, - Fe2O3: between 0 and 4%, for example between 0.5 and 2%, - less than 5% of other oxides, preferably less than 3% other oxides, - possibly water, preferably in a quantity less than 15% and in particular between 5 and 10%. A process 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: - SiO2: between 30 and 50%, preferably between 35 and 45%, - A12O3: between 0 and 10%, for example between 1 and 5% - MgO: between 25 and 45%, preferably between 30 and 40%, - MgO and SiO2, preferably representing a combined total of at least 70%, or even at least 75%, - Fe2O3: 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 magnesium source is a product obtained from the recycling of refractory bricks having in particular the following composition, in weight percentages: - SiO2: between 0 and 5%, preferably between 0 and 1.5%, - Al2O3: between 0 and 10%, for example between 2 and 7% - MgO: between 70 and 99%, preferably between 80 and 95%, - MgO and SiO2 together preferably representing 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, are further introduced into the melt bath. recycled glass cullet and / or recycled mineral fibers, preferably representing between 1 and 40% of the total weight of the melt pool.

13. A method 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 raw material mixture 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 (Al(OH)3) or calcined (Al2O3) alumina, a feldspar of general composition (K,Na)AlSi3O8 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).

15. A method 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 method 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, of

18. preferably more than 500 ppm of chromium oxide, preferably more than 700 ppm of chromium oxide. A 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 percentages: - SiO2: 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% - 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 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%, particularly between 0 to 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 with no fluorine at all. 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) or sodium carbonate (Na2) CO3 or a mixture of sodium hydroxide NaOH and sodium carbonate Na2CO3 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 more than 50% 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 mixture of raw materials in quantities such that the CaO / MgO ratio in the final target composition is less than 4, - the source(s) of B, Na, K, and optionally P and F are introduced into the mixture of raw materials 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.