Mineral wool

Abstract

A mineral wool having a chemical composition comprising the following components, in percentages by weight: SiO2 39-50% Al2O3 19.5-24.0% CaO 8-15% MgO 1-5% Na2O 5-20% K2O 0-15% Fe2O3 2-15% B2O3 0-2%, an MgO / RO mass ratio of greater than 0.10 and less than 0.50, an RO / (RO+R2O) mass ratio of less than 0.60, an (Na2O+MgO) / CaO mass ratio of greater than 0.8 and less than 1.4, and an (MgO+AI2O3) / Fe2O3 mass ratio of less than 5.0, wherein RO represents the alkaline-earth oxides CaO, MgO, BaO and SrO, and R2O represents the alkali oxides Na2O and K2O.

Description

Description TITLE OF THE INVENTION: MINERAL WOOL Technical field

[0001] The present invention relates to the field of artificial mineral wools. It relates more particularly to mineral wools intended for the manufacture of thermal insulation materials. It is particularly concerned with mineral wools for fire protection applications.

[0002] She is particularly interested in mineral wools whose chemical compositions result in a high liquidus temperature and high fluidity at their fiberizing temperature, associated with a high glass transition temperature. State of the art

[0003] Conventionally, this type of mineral wool is fiberized by so-called "external" centrifugation processes, for example of the type using a cascade of centrifugation wheels fed with molten material by a static distribution device, as described in particular in patents EP 0465310 or EP 0439385.

[0004] The so-called "internal" centrifugal fiberizing process, i.e. using centrifuges rotating at high speed and pierced with orifices, is, on the other hand, conventionally reserved for the fiberizing of mineral wool of the glass wool type, schematically of a composition relatively rich in alkali oxides and with a low alumina content, of lower liquidus temperature and whose viscosity at the liquidus temperature is greater than that of rock or basalt wool. This process is described in particular in patents EP 0189354 or EP 0519797.

[0005] Technical solutions for adapting the internal centrifugation process to the fiberization of rock wool are known in particular from WO 93 / 02977, by modifying the composition of the material constituting the centrifuges and their operating parameters. This adaptation therefore makes it possible to combine properties that were previously only inherent to one or other of the two types of wool, rock or glass. Thus, rock wool obtained by internal centrifugation is of a quality comparable to glass wool, with a lower fiber content than conventionally obtained rock wool. However, it retains the two advantages linked to its chemical nature, namely a low cost of raw materials and high temperature resistance.

[0006] In addition to the criteria of quality and industrial and economic feasibility, a health criterion is added. Mineral wools placed on the market must be biosoluble, i.e. have the capacity to dissolve quickly 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.

[0007] For some applications, it is desirable to have mineral wools with good resistance to very high temperatures. The fire resistance of a building element corresponds to the duration during which the element retains its load-bearing function, guarantees flame resistance and maintains its role as thermal insulation. The test Standard fire generally consists of a temperature rise following ISO 834, based on the temperature curve of a cellulosic fire.

[0008] Mineral wool compositions meeting the criteria of fiberability by internal centrifugation processes, biosolubility and good resistance to high temperatures have been developed. Such compositions are for example described in WO 2005 / 033032. However, to meet the requirements of resistance to very high temperatures, these mineral fibers must be coated with an organic phosphate additive as described in WO 2006 / 103375.

[0009] WO 2020 / 065191 describes mineral wool compositions having improved high temperature resistance properties while retaining rheological properties suitable for internal centrifugation processes. However, it has been found that significant quantities of spinel crystals can form at fiberizing temperatures in these compositions. The presence of these crystals can cause the orifices of the fiberizing members to clog and affect the fiberizing efficiency and / or the lifetime of the fiberizing members. Summary of the invention

[0010] The objective of the present invention is to provide mineral wool compositions which are both fibrable by internal centrifugation processes, generating little or no spinels at fiberizing temperatures, and capable of being biosoluble and resistant to very high temperatures without resorting to organic phosphate additives.

[0011] The fiber drawing process using these methods is optimal when the melt has a viscosity of 10 3 poises. The fiberizing temperature at which this viscosity must be reached (Tnb-Tiogs) must be less than 1220° C. On the other hand, since the temperature is not perfectly constant over time or perfectly homogeneous during fiberizing, a sufficient difference is necessary between the fiberizing temperature (Tfïb) and the liquidus temperature (Tüq). This difference, called the fiberizing range, must be at least 35° C to avoid any problems of devitrification and obstruction of the plates during fiberizing. This is why the liquidus temperature (Tü q ) must be less than 1185°C.

[0012] The subject of the invention is a mineral wool having a chemical composition comprising the following constituents, in weight percentages: SiO2 39-50%, preferably 39-49% AI2O3 19.5-24.0%, preferably 20-23% CaO 8-15%, preferably 10-14% MgO 1-5%, preferably 2-5% Na2O 5-20%, preferably 6-18% K2O 0-15%, preferably 1-12% Fe2O3 2-15%, preferably 3-12% B2O3 0-2%, preferably 0-1.5% a MgO / RO mass ratio greater than 0.10 and less than 0.50, preferably less than 0.40, or even less than 0.30, a RO / (RO+R2O) mass ratio less than 0.60, a (Na2O+MgO) / CaO mass ratio greater than 0.8 and less than 1.4, and a mass ratio (MgO+Al2Os) / Fe2O3 of less than 5.0, in which RO represents the alkaline earth oxides CaO, MgO, BaO and SrO, and R2O represents the alkali oxides Na2O and K2O.

[0013] Such compositions exhibit significantly improved very high temperature resistance properties while retaining desirable biosolubility and processability properties (Tfib~Ti og3 lower than 1220 0 C, Tiiq lower than 1180° C and Tnb-Tiiq higher than 35°C, little or no spinels). These combined properties were obtained in particular thanks to the choice of both the presence of magnesia, a relatively low alumina content (lower than 24.0%), well-defined balances between alkaline earth oxides and alkali oxides (0.10 <MgO / RO<0,50, RO / (RO+R2O)<0,60 et 0,8<(Na2O+MgO) / CaO<1 ,4), et entre l’alumine, la magnésie et l’oxyde de fer ((Mg0+Al203) / Fe203<5,0).

[0014] The invention also relates to a thermal and / or sound insulation product comprising a mineral wool described above.

[0015] The invention also relates to the use of the mineral wool described above in fire-resistant construction systems. Detailed description

[0016] In the compositions according to the invention, the sum of the contents of SiC>2, AI2O3, CaO, MgO, Na2O, K2O, Fe2O3 and B2O3 preferably represents at least 95%, in particular at least 97%, or even at least 98% by weight of the mineral wool composition.

[0017] The silica (SiO2) content ranges from 39 to 50%, including 49% or even 48%. A content above 50% may reduce the biosolubility of mineral fibers. A content below 39% may adversely affect the viscosity of the composition at fiberizing temperatures.

[0018] The alumina (AI2O3) content is in the range from 19.5 to 24.0%, including 20.0% or even 21% to 23.5% or even 23.0%. A content above 24% may promote the formation of spinels at fiberizing temperatures. A content below 19.5% may adversely affect the viscosity of the composition at fiberizing temperatures.

[0019] The lime (CaO) content ranges from 8 to 15%, including 9%, even 10%, or 10.5% to 14%. Contents below 8% can increase the liquidus temperature.

[0020] The magnesia (MgO) content ranges from 1% (or 1.0%) to 5%, including 1.5% or even 2% to 4% or even 3%. MgO contributes to resistance to very high temperatures. This relatively high MgO content also allows for the integration of a greater proportion of recycled materials, for example from mineral wool waste, such as deconstruction waste, including in particular rock wool.

[0021] Mineral wool does not generally contain any alkaline earth oxides other than CaO and MgO. However, it may contain small amounts of BaO or SrO, each at levels of up to 2%, or even 1%, 0.20%, or even 0.1%, these oxides being present as impurities in some raw materials.

[0022] The ratio of magnesium oxide to the sum of alkaline earth oxides RO (CaO, MgO, BaO and SrO): MgO / RO is greater than 0.10 and less than 0.50, especially from 0.11, or even 0.12 to 0.40, or even 0.38, 0.35 or even 0.30. A MgO / RO ratio less than 0.10 may affect the resistance at very high temperatures. On the contrary, a MgO / RO ratio greater than 0.50 may increase the liquidus.

[0023] The total content of alkali metal oxides (R2O), in particular sodium hydroxide (Na2O) and potassium hydroxide (K2O), is preferably greater than 12%. The Na2O content is in the range from 5 to 20%, in particular from 6%, or even 7%, to 18%, or even 15%, or 12%. The K2O content is at most 15%, in particular from 1%, or even 2%, to 12%, or even 10%, 8%, 5%, or 4%. The mineral wool preferably does not contain any other alkali metal oxide than Na2O and K2O. It may, however, contain small quantities of Li2O, sometimes present as an impurity in certain raw materials, at contents of up to 0.5%, or even 0.2%, or even 0.1%.

[0024] The RO / (RO+R2O) ratio is less than 0.60, in particular from 0.15, or even 0.20 or 0.30 to 0.59, or even 0.58. A RO / (RO+R2O) ratio greater than 0.60 can affect the fiberability of the composition.

[0025] The ratio (Na2O+MgO) / CaO is greater than 0.80 and less than 1.4, or even less than 1.3. A ratio (Na2O+MgO) / CaO less than 0.80 can affect the properties of resistance to very high temperatures. On the contrary, a ratio (Na2O+MgO) / CaO greater than 1.4 can affect the fiberability of the composition.

[0026] The iron oxide (Fe2O3) content ranges from 2 to 15%, including 3%, or even 4%, or 4.5% to 12%, or even 10%, or 8%. Expressing the (total) iron oxide content as Fe20s does not mean that this iron oxide is necessarily and exclusively present in the glass in the ferric form. Glass generally contains iron oxide in both its ferric (Fe2O3) and ferrous (FeO) forms, and it is purely by convention that the total iron oxide content is referred to as Fe2O3. Iron oxide has a positive effect on the high-temperature resistance of mineral wool.

[0027] The ratio (MgO+Al2Os) / Fe2O3 is less than 5.0, especially from 2.0, or even 3.0 to 5.0. A ratio greater than 5.0 can promote the formation of spinels at fiber drawing temperatures and / or affect the strength at very high temperatures.

[0028] The boron oxide (B2O3) content is at most 2%, in particular 0.1%, or even 0.5%, to 1.5%, or even 1%. The presence of boron may be advantageous for improving the biosolubility of the fibers and / or improving their insulating properties. In certain embodiments, the composition comprises less than 1% B2O3.

[0029] The mineral fiber composition according to the invention may also contain P2O5, in particular at contents of up to 3%, or even up to 1.2%, to increase biosolubility at neutral pH. However, it is preferably essentially free of P2O5, which may nevertheless be present as impurities of up to 0.5%.

[0030] The composition according to the invention may also comprise other elements present in particular as unavoidable impurities. It may comprise titanium oxide (TiC) and zirconia (ZrC) each at contents within a range of up to 3%, in particular 0.1 at 2.0%, or even 1.0%. The composition is preferably essentially free of halogens, in particular fluorine. It typically comprises less than 1%, or even less than 0.5%, of halogens, in particular fluorine.

[0031] It goes without saying that the various preferred ranges described above can be freely combined with each other, although not all the different combinations can be listed for the sake of brevity.

[0032] According to a preferred embodiment, the mineral fibers according to the invention have a chemical composition comprising the following constituents, in weight percentages: SiO239 at 48% AI2O3 20 to 23%, preferably 21 to 23% CaO 10 to 14% MgO 2 to 4% Na2O 7 to 15% K2O 2 at 8% Fe2O3 3 to 8% B2O30 at 1% a MgO / RO mass ratio greater than 0.10 and less than 0.50, preferably less than 0.40, or even less than 0.30, a RO / (RO+R2O) mass ratio less than 0.60, a (Na2O+MgO) / CaO mass ratio greater than 0.8 and less than 1.4, and a (MgO+AI2O3) / Fe2O3 mass ratio less than 5.0.

[0033] The invention also relates to a process for obtaining mineral fibers according to the invention, comprising a step of melting a vitrifiable mixture having substantially the same chemical composition as that of said mineral fibers; then a fiberizing step, in particular by internal centrifugation.

[0034] The melting stage produces a molten bath from a vitrifiable mixture. The vitrifiable mixture includes various natural and / or artificial raw materials, for example silica sand, phonolite, dolomite, sodium carbonate, etc.

[0035] The melting step can be carried out in various known ways, including melting in a flame furnace or by electric melting.

[0036] The flame furnace comprises at least one burner, either overhead (the flames are arranged above the molten material bath and heat it by radiation) or submerged (the flames are created directly within the molten material bath). The or each burner can be fueled by various fuels such as natural gas or fuel oil.

[0037] By "electric melting" is meant that the vitrifiable mixture is melted by the Joule effect, using electrodes immersed in the molten bath, excluding any use of other heating means, such as flames. The vitrifiable mixture is normally distributed homogeneously over the surface of the molten bath using a mechanical device, and thus constitutes a thermal shield limiting the temperature above the molten bath, so that the presence of a superstructure is not always necessary. The electrodes can be suspended so as to immerse themselves in the molten bath from above, be installed in the floor, or be installed in the side walls of the tank. The first two options are generally preferred for large tanks in order to best distribute the heating of the molten material bath. The electrodes are preferably made of molybdenum, or possibly even tin oxide or graphite. The molybdenum electrode is preferably passed through the bottom via a water-cooled steel electrode holder.

[0038] The melting step may also involve both flame melting and electric melting, for example by using a flame furnace also equipped with sidewall electrodes to accelerate the melting of the vitrifiable mixture.

[0039] The fiberizing step is preferably carried out by internal centrifugation.

[0040] The resulting fibers may be bonded together using a sizing composition sprayed onto their surface, before being received and shaped to produce various mineral wool products, such as rolls or panels. The mineral wool products thus bonded preferably comprise at most 15% by dry weight of binder relative to the total weight of binder and mineral fibers.

[0041] In order to obtain even better fire resistance, the mineral wool may comprise a phosphorus additive, preferably sprayed at the same time as the sizing composition. The phosphorus additive may be a mineral additive, as described in application WO 01 / 68546 or a phosphated organic additive, for example an oligomer or polymer of the phosphonic or phosphoric polyacid or polyester type, as taught by application WO 2006 / 103375. The mineral wool compositions according to the invention, however, have the advantage of intrinsically having very good resistance properties at very high temperatures. The use of phosphorus additives makes it possible to further improve these performances. The use of such phosphorus compounds is however not necessary even for certain very demanding applications requiring protection against fire. In certain embodiments, the mineral wool does not comprise a phosphorus additive.

[0042] The invention also relates to a thermal insulation product comprising mineral fibers according to the invention. Such a product is in particular in the form of rolls or panels. It can be used, for example, in buildings, in industry or in means of transport, in particular rail or maritime. It is particularly suitable for applications in which it may be subjected to high temperatures, either continuously (insulation of domestic or industrial ovens or furnaces, fluid transport pipes) or accidentally, in a role of protection against fire (fire doors, insulation of ships, tunnels or offshore platforms- ••). More generally, the product according to the invention can be used to thermally insulate any type of building, tertiary or residential (collective or individual).For example, it can be used in external insulation systems, for the insulation of timber-framed houses, in sandwich panels, in ventilation ducts, etc.

[0043] The invention also relates to the use of the mineral wool described above in fire-resistant construction systems.

[0044] "Fire-resistant construction systems" are systems, generally comprising assemblies of materials, particularly based on mineral wool and metal plates, capable of delaying effectively spread heat as well as provide protection against flames and hot gases and maintain mechanical strength during a fire.

[0045] Standardized tests define the degree of fire resistance, expressed in particular as the time required for a given temperature to be reached on the opposite side of the construction system subjected to a heat flow, released for example by the flame of a burner or an electric oven.

[0046] A construction system is considered to have a satisfactory fire resistance capacity, in particular if it is capable of meeting the requirements of one of the following tests: - test for fire door: tests on mineral fiber boards as defined in the German standard DIN 18 089 - Teil 1 (or equivalent). - Fire behaviour of materials and elements for construction as defined in the German standard DIN 4102 (or equivalent). In particular, DIN 4102 - Part 5 is considered for full-scale tests to determine the fire resistance class, and / or DIN 4102 - Part 8 for tests on samples with a small test bench. - Test according to the IMO A 754 (18) standard test (or equivalent) which describes the general requirements for fire resistance tests for “marine” type applications, including ship partitions. These tests are carried out on large samples, with ovens measuring 3 m by 3 m. An example is a steel bridge where the required performance in the event of a fire on the insulation side is to satisfy the thermal insulation criterion for at least 60 minutes.

[0047] The following examples illustrate the invention in a non-limiting manner.

[0048] Examples

[0049] Examples of glasses (example 1 according to the invention and comparative examples C1 to C5) whose weight compositions are presented in table 1 were developed.

[0050] Compositions are considered to have satisfactory fiberizing properties (OK), particularly for internal centrifugal fiberizing processes, if they have a fiberizing temperature (Tnb- Tiogs) below 1220°C, a liquidus temperature Tü q less than 1180°C and a Tfib-Tiiq fiberizing range greater than 35°C. Conversely, the fiberizing properties are not satisfactory (NOK) if one of these conditions is not met.

[0051] Slump is determined by thermomechanical analysis. The resulting glasses are ground into powder with a particle size of less than 40 μm. Each glass powder is compacted into cylindrical pellets 5 mm in diameter and approximately 1 cm high, with a density equal to 64% of that of glass. Slump, expressed as a percentage, corresponds to the variation in the height of a glass powder pellet subjected to a ramp of 10 K / min from room temperature to 1100°C compared to the initial height of the pellet. The height of the sample is measured using a probe placed at the top of the cylinder. Repeatability tests allow a standard deviation of less than 1% to be defined. A slump of less than 12% is considered satisfactory (OK) to obtain resistance to the desired cellulosic fire curve. Conversely, a slump greater than 12% does not allow satisfactory resistance (NOK) to be obtained to the cellulosic fire curve.

[0052] The presence of spinels is measured by microscopic analysis. The resulting glasses are ground into powder with a particle size between 815 pm and 2 mm. The powders are annealed at temperatures between Tlog3+50 °C and Tlog3-50 °C. The presence of spinel crystals is characterized by preparing a thin section of the annealed glass and observing it by optical or even electronic microscopy.

[0054] [Table 1] nm: not measured

[0055] The composition of Example 1 according to the invention exhibits low slump of less than 12% which is maintained up to 1100°C, indicating good resistance at very high temperatures. This composition also exhibits a temperature Ti og 3 lower than 1220°C, a temperature Tü qless than 1180°C and a fiberizing range greater than 35°C, which allows fiberizing by internal centrifugation without risk of devitrification. It also does not exhibit spinel formation at fiberizing temperatures which are likely to affect the fiberizing efficiency and / or the lifetime of the fiberizing members. On the contrary, the compositions of comparative examples C1 to C6 do not allow all of these criteria to be met. Compositions C1, C2, C3, C6 and C7 do not exhibit sufficient resistance at very high temperatures. In particular, composition C6 exhibits a collapse in slump from 1000°C to reach more than 20% at 1100°C. Compositions C1 and C4 do not exhibit satisfactory fiberizing properties, in particular due to a Tü q too high to be able to be fiberized by internal centrifugation. Finally, the formation of spinels is observed at fiberizing temperatures for compositions C5 and C7.

Claims

Claims Claim 1. Mineral wool having a chemical composition comprising the following constituents, in weight percentages: SiO239-50% AI2O3 19.5-24.0% CaO 8-15% MgO 1-5% Na2O 5-20% K2O 0-15% Fe2O32-15% B2O30-2%% a MgO / RO mass ratio greater than 0.10 and less than 0.50, a RO / (RO+R2O) mass ratio less than 0.60, a (Na2O+MgO) / CaO mass ratio greater than 0.8 and less than 1.4, and a (MgO+AI2O3) / Fe2O3 mass ratio less than 5.0, in which RO represents the alkaline earth oxides CaO, MgO, BaO and SrO, and R2O represents the alkali oxides Na2O and K2O. Claim 2. Mineral wool according to claim 1, characterized in that the R2O content is greater than 12%. Claim 3. Mineral wool according to claim 1 or 2, characterized in that the composition comprises 0 to 0.20% BaO. Claim 4. Mineral wool according to one of claims 1 to 3, characterized in that the SiO2 content is 39 to 48%. Claim 5. Mineral wool according to one of claims 1 to 4, characterized in that the AI2O3 content is 20 to 23%. Claim 6. Mineral wool according to one of claims 1 to 5, characterized in that the CaO content is 10 to 14%. Claim 7. Mineral wool according to one of claims 1 to 6, characterized in that the MgO content is 2 to 4%. Claim 8. Mineral wool according to one of claims 1 to 7, characterized in that the Na2O content is 7 to 12%. Claim 9. Mineral wool according to one of claims 1 to 8, characterized in that the K2O content is 2 to 5%. Claim 10. Mineral wool according to one of claims 1 to 9, characterized in that the Fe2O3 content is 4.5 to 8%. Claim 11. Thermal and / or acoustic insulation product comprising a mineral wool according to one of claims 1 to 10. Claim 12. Use of a mineral wool according to one of claims 1 to 10 in fire-resistant construction systems or insulators used at high temperatures.

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