HRP20000009A2 - Mineral wool composition - Google Patents

Description

The present invention relates to the field of artificial mineral wool. It relates primarily to mineral wool intended for the production of thermal and/or acoustic insulation materials or for non-earthen substrates for growing crops.

The present invention relates in particular to mineral wool of the stone wool or basalt wool type, meaning those whose chemical composition includes a high liquidus temperature and high fluidity at the temperature of their fiberization.

Usually, this type of mineral wool is fiberized by a process of so-called "external" centrifugation, for example using a cascade of spin wheels that are filled with molten material by means of a static filling device, as described primarily in patents EP-0,465,310 or EP-0,439,385.

In recent years, to the well-known criteria for industrial and economic feasibility and for the level of quality, those about the biodegradability of mineral wool, namely its ability to quickly dissolve in the physiological environment, have been added, in order to prevent any potential pathogenic risk associated with the possible accumulation of the finest fibers in the body, which would come by inhalation.

The subject of the invention is therefore the improvement of the chemical composition of stone or basalt type mineral wool, whereby the improvement is primarily aimed at increasing its biodegradability and/or harmonizing biodegradability with the ability to defiber by external centrifugation (however, without excluding other defibrization methods).

The subject of the invention is mineral wool that can be dissolved in a physiological medium, and which contains the following ingredients in the following mass percentages:

SiO2 38 - 46 %, preferably 40 %

Al2O3 16 - 24 %

RO (CaO 1/or MgO) 16 - 40 %

MgO 10 - 20 %

MgO/CaO ≥ 0.8, (111 > 0.7, preferably ≥ 0.75)

R2O (Na2O and/or K2O) ≥ 0.3 %

P2O5 0 - 5 %

Fe2O3 (total iron) > 0.5 %

TiO2 0 - 3 %

MnO 0 - 2 %

SO3 0-2%

(Throughout the text, the meaning of mass percentage should be understood for each percentage of the ingredients of the composition.)

The selection of such a composition enabled the development of a wide range of advantages, primarily by varying the many complex roles played by a number of its specific constituents.

Therefore, it is a mineral wool composition of the rock wool type, in which the content of alkali metal oxides (R2O) essentially in the form of Na2O and/or K2O is moderate or even low, generally less than 6%. At the same time, its content of alkaline earth metal oxides (RO), which are essentially in the form of CaO and/or MgO, is high, generally at least 20% and even at least 22%.

The general contents of MnO, TiO2 and SO2 should be considered more like the contents of impurities that often exist in this type of composition: in general, the total content of impurities up to 3% can be found in the compositions.

The viscosity of such a composition during fiberization is suitable for internal centrifugation.

Regarding biodegradability, it was already known that some compounds such as P2O5 can significantly improve it, primarily in glass wool-type compositions, while other oxides such as aluminum, on the contrary, seem to have a tendency to decrease it, at least at neutral pH. This is evident, for example, from patents EP-0,459,897 1 WO 93/22251. However, a large addition of P2O5 did not prove to be the most prudent approach in the context of the invention. Because of this, there may be other considerations, for example economic ones (P2O5 is obtained from expensive raw materials) as well as technical ones - changes in the ratio of P2O5 and aluminum oxide in the composition can cause changes in other properties in an undesirable or unknown way. Therefore, P2O5 is not without influence on the viscosity of the composition, and the same is true for aluminum oxide. However, primarily in the case of stone wool-type compositions that need to be spun by external centrifugation, and to which the invention relates in particular, the viscometric behavior of the composition is an important criterion that needs to be controlled.

Moreover, some compounds can be useful for achieving some properties, but disadvantageous for obtaining a high degree of biodegradability, as seems to be the case with iron, which is useful for example for achieving high fire resistance of mineral wool, but which causes a decrease in the biodegradability of rock wool, or the case with aluminum oxide, which is prudent to use to regulate the viscosity of the composition, but is not very favorable in terms of biosolubility, especially if it is measured by in vitro tests at neutral pH.

Therefore, the invention established a prudent compromise between all these data as follows: the composition may contain P2O5, but in moderate amounts of no more than 5%, preferably no more than 4%. It also contains at least a small amount of iron oxide, which may prove beneficial (or unavoidable in trace amounts), but for reasons other than biodegradability. However, the composition achieves a high degree of biodegradability without the addition of excessive amounts of P2O5, or even without P2O5 at all (or any other special compound considered favorable for achieving biodegradability), in another way that primarily consisted in varying the relative ratio of MgO to CaO. In fact, stone wool-type compositions generally contained a proportion of lime CaO noticeably higher than that of magnesium oxide MgO. By modifying this ratio, it was found that a high degree of biodegradability can be achieved with a high content of P2O5, which "compensates" for the significant contents of aluminum and iron oxides. Furthermore, but not insignificantly, one should note the advantage associated with a low P2O5 content, namely an excessive amount of P2O5 actually increases the temperature of the liquidus of the composition.

Another characteristic aspect according to the invention relates to the combination of this particular MgO/CaO ratio with a relatively high content of aluminum oxide, since this amounts to at least 16%. This combination was found to meet biosolubility criteria, measured both by in vitro tests at neutral pH and by in vitro tests at acidic pH. In fact, the knowledge about the pH range that would be the most representative as a physiological environment in vivo, primarily that for the pulmonary areas, has not been definitively resolved so far. So far, high alumina contents appeared to be suitable for rapid dissolution in the acidic pH range, but not in the neutral pH range.

The invention makes it possible to obtain high levels of biosolubility, at least measured in vitro, at any pH, by choosing a high content of aluminum oxide, but with the adjustment of the content of primarily alkaline earth metal oxides, so that their beneficial effect is maintained in acidic pH without a negative impact in neutral pH.

It should be noted that the sum of SiO2 + Al2O3 enables significant control of the viscometric behavior of the composition, and is primarily at least 58%, and especially between 59 and 64%.

First of all, the mineral wool compositions according to the invention have a content of oxides of alkaline earth metals RO (CaO and/or MgO) either between 18 1 32%, for example between 26 1 30%, or more than 32% and even up to 40%.

Similarly, according to the first form, the contents of iron oxide Fe2O3 can be very moderate, preferably from 0.5 to 1.7 % (they are generally combined with a high RO content, greater than 32 %). This low content makes it possible to obtain what is sometimes called "white wool", which is used primarily as mineral wines sprayed on construction components.

According to another embodiment, the iron content is higher, preferably higher than 1% and up to 12% Fe2O3, and in particular from 5 to 10% or from 5 to 8% Fe2O3 (generally combined with an RO content of 18 to 32%). As 9, it was mentioned earlier, iron can primarily give mineral wool fire resistance. In this form, mineral wool is generally collected in the form of pressed mass.

First of all, the R2O content (Na2O and/or K2O) can be either between 0.3 and 1% (primarily for the purpose of producing the aforementioned white wool) or more, in particular more than 1% to almost 6%, for example at least 2 to 2.2% or between 1 and 3 %.

Preferably, the compositions according to the invention also satisfy the following ratio, expressed as a mass percentage ratio: MgO/CaO more than 0.85, preferably more than 0.95 or 1 or 1.15. and generally at most 2 or 3. Therefore, the above-mentioned beneficial effect is obtained without an excessive excess of MgO in relation to CaO, making it additionally complex or expensive to obtain these oxides as raw materials. As mentioned above, it is also possible to use slightly lower ratios, for example a MgO/CaO ratio between 0.75 and 0.80.

Also advantageously, the compositions according to the invention can meet the R2O/Al2O3 ratio in the range between 0.07 and 0.8, preferably between 0.09 and 0.3 or between 0.05 and 0.2.

Compositions according to the invention preferably have a P2O5 content higher than 0.1%, and especially 2 to 3%. This moderate content has a very favorable impact on biodegradability, without economically too bad an impact on the composition and without too much impact on its liquidus temperature.

According to another embodiment, the P2O5 content can be lower, preferably equal to zero or slightly higher, and up to 0.1%.

The oxidation of the composition can be controlled, for example, by the optional addition of manganese oxide MnO, preferably in an amount of 0.1 to 4%.

The addition of boron oxide, which is also optional 1 preferably in the amount of 0.1 to 5%, can improve the technical insulating properties of mineral wool, primarily by lowering its coefficient of thermal conductivity in radiative components.

The optional composition may also contain TiO2, either as an impurity or added intentionally, for example in a quantity of 1 to 2 %. SO3, as well as P2O5, should also be considered an impurity, especially when it exists in values of less than 0.1%.

Advantageously, the composition according to the invention contains CaO, which is less than or equal to 22%, preferably at least 10%, preferably between 11 1 18%, 111 more than 18% and up to 21%.

In parallel, the MgO content in the composition is preferred, which is at least 11%, and generally at most 19%, while the range between 12 and 15% is preferred.

According to the preferred, non-limiting aspect of the invention, the content of aluminum oxide Al2O3 in the composition is at least 18.5%, preferably at least 19%, and even at least 20 or 21%.

The difference Tlog1 - Tliq is preferably at least 10 °C, preferably at least 20 or 30 °C: this difference defines the "working range" of the composition according to the invention, i.e. the temperature range in which they can be defiberized, preferably by external centrifugation.

Such mineral wool, as mentioned above, has a satisfactory level of biosolubility, whether the measuring method involves a neutral or slightly basic pH, or an acidic pH.

Such mineral wool according to the invention therefore generally has a solubility rate of at least 30, or preferably at least 40 or even 50 ng/cm2 per hour (preferably measured on silicate) measured at pH 4.5, and at least 30 and preferably at least 40 or even 50 ng/cm2 per hour (primarily measured on silicate) measured at pH 7.5.

In general, such mineral wool also has a dissolution rate of at least 30 1 preferably at least 40 or even 50 ng/cm2 per hour measured at pH 4.5, and a dissolution rate of at least 30 and preferably at least 40 or even 50 ng/cm2 measured at pH 6.9 ( again, primarily measured on silicate).

Generally, it also has a solubility rate of at least 60 1 preferably at least 80 ng/cm 2 per hour measured at pH 4.5 1/or a dissolution rate of at least 40 1 preferably at least 60 ng/cm 2 measured at pH 6.9 and/or measured at pH 7.5 ( preferably measured on silicate).

Mineral wool is mainly used for the production of thermal and/or acoustic insulation products or for non-earth substrates for growing crops. The subject of the invention is also any product that contains, at least partially, such mineral wool as described above.

Further details and advantageous features will appear of their own accord from the following description of preferred embodiments, which do not limit the invention.

Table 1 below shows the chemical compositions of fifteen examples, expressed in mass percentages.

When the sum of all contents of all compounds is slightly less than or greater than 100%, it should be understood that the difference up to 100% corresponds to minor impurities/components (which are not quantitatively determined), which content amounts to a maximum of 0.5 to 1%, and/or the difference should be attributed only the accepted approximation in the analytical method applied in this area.

The compositions according to these examples are defibered by external centrifugation, especially according to the teachings of the previously mentioned patents.

Table 1

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Table 1 (cont

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Their working areas, defined by the Tlog1 - Tliq difference, are significantly positive.

All compositions have a MgO/CaO ratio greater than 0.8 and even greater than 0.85, and a very moderate P2O5 content (less than 1%) or none. They also have a high aluminum oxide content of approximately 17 to 23%. Except for example 6, all examples have an Fe2O3 content of approximately 6 to 8%. Example 6, with very little iron and a large amount of alkaline earth metal oxides, enables the production of the aforementioned "white" stone wool.

Their biodegradability is satisfactory, and was primarily measured at neutral or slightly acidic pH (pH 6.9 or 7.5), or at acidic pH (4.5).

Table 2 shown below shows the results of measuring the dissolution rate of silicate in mineral wool according to examples 9, 10 and 11, marked as "KSiO2 expressed in ng/cm2 per hour:

→ according to an in vitro test in a medium buffered to an acidic pH

(4.5), called "acid medium",

→ according to the in vitro test in the medium buffered to the value

pH approximately 7.4 to 7.5, called "neutral medium".

Table 2

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From these results, the conclusion seems to emerge, that with a higher content of aluminum oxide, the rate of dissolution increases in acidic pH, and to a lesser extent, also 1 in neutral pH.

Two additional examples, examples 16 and 17, satisfying the formulation described above with an MgO/CaO ratio of 0.75, also proved to be useful.

The compositions are detailed in Table 3 below, with the same constituents as in Table 1.

Table 3

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Claims (16)

1. Mineral wool that can be dissolved in a physiological environment, characterized by the fact that it contains the following ingredients in the following mass percentages: SiO2 38 - 46 %, preferably 40 % Al2O3 16 - 24 % MgO 10 - 20 % RO (CaO + MgO) 16 - 40 % MgO/CaO ≥ 0.8 R2O (Na2O + K2O) ≥ 0.3 % P2O5 0 - 5 % Fe2O3 (total iron) > 0.5 % 'IiO2 0 - 3 % MnO 0 - 2 % SO3 0 - 2 % 2. Mineral wool according to claim 1, characterized in that it contains oxides of RO (CaO + MgO) in the following mass percentages: RO, 18 - 32%, or more than 32%. and up to 40%. 3. Mineral wool according to any of the preceding claims, characterized in that it includes Fe2O3 content (total iron) in the following mass percentages: 0.5 to 1.7%, 111 more than 1.7%, and up to 12%. 4. Mineral wool according to one of the previous claims, characterized in that it contains oxides R2O (Na2O + K2O) in the following percentages: 0.3 to 1%, or more than 1% 1 to 6%. preferably at least 2 or 2.2 %. 5. Mineral wool according to one of the previous requirements, indicated by the fact that it meets the ratio: MgO/CaO > 0.85, preferably > 0.95, especially > 1 or > 1.15. 6. Mineral wool according to one of the previous requirements, indicated by the fact that it meets the ratio: R2O/Al2O3 = 0.07 - 0.8. preferably 0.09 to 0.3. 7. Mineral wool according to one of the previous claims, characterized by the fact that it contains from 0 to 0.1 % P2O3 or more than 0.1 %, 1 to 2 or 3 %. 8. Mineral wool according to one of the previous claims, characterized in that it contains MnO, preferably in an amount of 0.1 to 4%, and/or B2O3, preferably in an amount of 0.1 to 5%. 9. Mineral wool according to one of the previous claims, characterized in that it contains MgO in the following percentages by mass: MgO ≥ 11%. preferably 19 %, especially between 12 1 15 %. 10. Mineral wool according to one of the preceding claims, characterized in that it contains CaO in the following mass percentages: CaO = 22%, preferably 10%, especially between 11 and 18%, or more than 18%, 1 to 21%. 11. Mineral wool according to one of the previous claims, characterized in that it contains Al2O3 in the following percentages: Al2O3 ≥ 18.5 %, preferably ^ 19 % or > 20 %. 12. Mineral wool according to one of the preceding claims, characterized in that it has a dissolution rate of at least 30 ng/cm2 per hour measured at pH 4.5 and a dissolution rate of at least 30 ng/cm2 per hour measured at pH 7.5. 13. Mineral wool according to one of the preceding claims, characterized in that it has a dissolution rate of at least 30 ng/cm2 per hour measured at pH 4.5 and a dissolution rate of at least 30 ng/cm2 per hour measured at pH 6.9. 14. Mineral wool according to one of the preceding claims, characterized in that it has a dissolution rate of at least 60 ng/cm2 per hour measured at pH 4.5 and/or a dissolution rate of at least 40 ng/cm2 per hour measured at pH 7.5 and/or a rate of dissolution of at least 40 ng/cm2 per hour measured at pH 6.9. 15. Mineral wool according to one of the previous claims, characterized in that it is obtained by external centrifugation. 16. Thermal and/or acoustic insulating products or substrate for cultures without the presence of soil, characterized by the fact that they contain, at least partially, mineral wool according to one of the previous requirements.