FR2778400A1 - COMPOSITION OF MINERAL WOOL - Google Patents

Abstract

The invention concerns a mineral wool capable of dissolving in a physiological medium, comprising the following constituents in weight percentages as follows: SiO2 38-46 %; Al2O3 16-24 %; MgO 10-20 %; RO (CaO + MgO) 16-40 %; MgO/CaO >/= 0.8 %; R2O (Na2O + K2O) >/= 0.3 %; P2O5 0-5 %; Fe2O3 >/= 0.5 %; TiO2 0-3 %; MnO 0-2 %; SO3 0-2 %.

Description

COMPOSITION OF MINERAL WOOL

  The present invention relates to the field of artificial mineral wools. It relates more particularly to mineral wools intended for manufacturing thermal and / or acoustic insulation materials or

soilless growing media.

  It is more particularly interested in mineral wools of the rock wool, basalt type, that is to say whose chemical compositions cause a relatively high liquidus temperature and great fluidity at their

fiber drawing temperature.

  Conventionally, this type of mineral wool can be fiberized by so-called "external" centrifugation processes, for example of the type of those using a cascade of centrifugation wheels supplied with molten material by a static distribution device, as described in particular in

  EP-0 465 310 or EP-O 439 385.

  To the known criteria of industrial and economic feasibility, of level of quality, has been added for a few years that of a biodegradable character of mineral wool, namely the capacity of this wool to dissolve quickly in physiological medium, in order to prevent any potential pathogenic risk linked to the possible accumulation of the finest fibers

into the body by inhalation.

  The object of the invention is therefore to improve the chemical composition of mineral wools of the rock or basalt type, an improvement aimed in particular at increasing their biodegradable nature and / or reconciling a biodegradable character with an ability to be fiberized by external centrifugation (without

  exclude other fiberizing methods, however).

  -2- The subject of the invention is a mineral wool capable of dissolving in a physiological medium, which comprises the following constituents according to the following weight percentages: SiO2 38-46%, in particular at least 40%

A1203 1 6-24%

  RO (CaO and / or MgO) 16-40% MgO 10-20% MgO / CaO> 0.8 R20 (Na20 and / or K20)> 0.3%

P205 0-5%

  Fe203 (total iron)> 0.5% TiO2 0-3% MnO 0-2%

S03 0-2%

  (Throughout the rest of the text, any percentage of a constituent of the composition should be understood as a weighted percentage). The selection of such a composition made it possible to combine a whole series of advantages, in particular by playing on the multiple, complex roles that

  play a number of its specific constituents.

  Thus, it is indeed a composition of mineral wool of rock type its rate in alkaline oxides (R20) essentially in Na20 and / or K20 form is moderate or even very low, generally lower than 6%. And at the same time, its level of alkaline earth oxides (RO), essentially in the CaO and / or MgO form, is high, generally at least 20% and even rather at least

minus 22%.

  The possible contents of MnO, TiO2 and S03 are rather to be considered as contents of impurities frequently encountered in this family of compositions: generally one counts up to 3% in rate of impurities

overall in the compositions.

  The fiber viscosity of such a composition is suitable for a

external centrifugation.

  - 3 - As for the biodegradable nature, it was already known that certain compounds made it possible to improve it considerably in compositions of the rock type in particular, such as P205, while other oxides appeared on the contrary to tend to decrease it, at least at neutral pH. Reference may be made, for example to patents EP-O 459 897 and WO93 / 22251. However, a massive addition of P205 has not proved to be the most judicious route in the context of the invention. Indeed, other considerations, for example economic, (P205 coming from expensive raw materials) and also technical considerations may intervene: changes in the proportions of P205, and for example of alumina, in the composition can vary it from other properties in an undesirable or unknown sense. Thus, P205 is not without influence on the viscosity of the composition, like alumina. However, for rock-type compositions to be fiberized by external centrifugation, those which most interest the invention, the viscosimetric behavior of the composition is an important criterion to be controlled. In addition, certain compounds can be advantageous for certain properties and yet be unfavorable for a high biodegradability, which appears to be the case with iron, advantageous for example to give mineral wool good fire resistance, but which could tend to reduce the biodegradability of rock wool, or in the case of alumina, which is judicious for regulating the viscosity of the composition but which may not be very favorable with regard to biosolubility, in particular measured by in vitro tests at pH neutral. The invention then established a judicious compromise between all of these data, essentially as follows: the composition may contain

  P205, but in a moderate content of at most 5%, and rather at most 4%.

  It also contains at least a low content of iron oxide, which may prove advantageous (or inevitable in trace amounts) but for reasons other than biodegradability. However, it achieves a high level of biodegradability without excessive addition of P205 or even without P205 at all (or any other very particular compound supposed to be favorable to biodegradability), by another means, which consisted, in particular, in acting on the relative proportion -4 - in MgO relative to CaO. In fact, generally, rock-type compositions contain a CaO lime content very much higher than that of MgO magnesia. It turned out that by modifying this ratio, it was possible to reach the high level of biodegradability which until then could only be obtained with high levels of P205 to "compensate"> for significant levels of alumina and / or iron. Note a non-negligible subsidiary advantage linked to a low P205 level: too much P205 tends to

  increase the liquidus temperature of the composition.

  Another characteristic feature according to the invention relates to the combination of this particular MgO / CaO ratio with a fairly high level of alumina, since at least 16%. It turned out that this combination made it possible to satisfactorily meet the criteria of biosolubility, as well measured according to in vitro tests at neutral pH as according to in vitro tests at acid pH. Indeed, it has not been decided definitively on the point of knowing which pH was the most representative of the physiological medium in vivo, notably that of the pulmonary regions. A high level of alumina seemed so far to be favorable

  to rapid dissolution at acid pH but not at neutral pH.

  The invention makes it possible to obtain a high level of biosolubility, at least measured in vitro, whatever the pH, by selecting a high level of alumina, but in particular by adapting the content of alkaline earth oxides so as to

  keep its beneficial effect at acidic pH without being penalizing at neutral pH.

  Note that the sum SiO2 + A1203 makes it possible to regulate for a large part the viscosimetric behavior of the compositions and that it is

  preferably at least 58%, especially between 59 and 64%.

  Advantageously, the mineral wool compositions according to the invention contain an RO content of alkaline earth oxides (CaO and / or MgO), ie

  between 18 and 32%, or more than 32% up to 40%.

  Similarly, the Fe203 iron contents can be, according to a first very moderate variant, from 0.5 to 1.7% in particular (generally combined with a high RO content, greater than 32%). This low content makes it possible to obtain what is sometimes designated by the term "white wool", used in particular for mineral wool applications by spraying onto

building elements.

  - 5 - According to a second variant, the iron content is higher, with in particular more than 1.7% up to 12% in Fe203, and preferably from 5 to 10%

  as Fe203 (generally combined with an RO content of 18 to 32%).

  As mentioned above, iron in particular makes it possible to impart good fire resistance to mineral wools. In this variant, the mineral wool is

  generally assembled in felt.

  Advantageously; the content of oxides R20 (Na2O and / or K20) can be either between 0.3 and 1% (preferably for the purpose of manufacturing the white wool mentioned above), or higher, in particular by more than 1%

  almost 6%, for example at least 2 to 2.2%.

  Advantageously, the compositions according to the invention also respect the following relationship, expressed in a ratio of weight percentages: MgO / CaO greater than 0.85, in particular greater than 0.95 or 1 or 1.15, and generally at most 2 or 3. The advantageous effect mentioned above is thus obtained, without too great an excess of MgO compared to CaO making the supply of raw materials of these oxides too

complicated or expensive.

  Advantageously also, the compositions according to the invention can respect the relationship R20 / AI203 of between 0.07 and 0.8, preferably

between 0.09 and 0.3.

  The compositions according to the invention preferably have a P205 level of more than 0.1%, and in particular up to 2 to 3%. This moderate rate influences the biodegradability very advantageously, without economically penalizing the

  composition nor influence too much on its liquidus temperature.

  According to another variant, the level of P205 can be lower, in particular

from 0% to 0.1%.

  The oxidation of the composition can for example be controlled by the optional addition of manganese oxide MnO, in particular in a content of

0.1 to 4%.

  Adding boron oxide, which is also optional and in particular of a content of 0.1 to 5%, can make it possible to improve the thermal insulation properties of mineral wool, in particular by tending to lower its

  coefficient of thermal conductivity in its radiative component.

  Optionally, the composition can also contain TiO2 as impurities or added voluntarily, for example in a content up to 1 to 2%. S03 is also to be considered as an impurity, just like

  P205 when it is confined to values below 0.1% in particular.

  The preferential CaO content of the composition according to the invention is less than or equal to 22%, in particular at least 10%, advantageously between

  1 1 and 18% or more than 18 up to 21%.

  In parallel, the preferential MgO content of the composition is preferably at least 11% and generally at most 19%, the range

  preferred being between 12 and 15%.

  According to a preferred nonlimiting embodiment of the invention, the alumina A1203 content of the compositions is at least 18.5%, in particular 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 level" of the compositions of the invention, that is to say the range of temperatures in which they can be fiberized, particularly by external centrifugation. Mineral wools, as mentioned above, have a satisfactory level of biosolubility, that the measurement method involves a neutral pH,

  slightly basic, or acidic pH.

  The mineral wools according to the invention thus generally have a dissolution rate of at least 30, and preferably at least 40 and even at least 50 ng / cm2 per hour (in particular measured on silica) measured at pH 4.5 and at least 30, and preferably at least 40 and even at least 50 ng / cm2 per hour (in particular measured on silica) measured at pH 7.5. They also generally have a dissolution rate of at least 30, and preferably at least 40 and even 50 ng / cm 2 per hour measured at pH 4.5 and a dissolution rate of at least 30, and preferably at least 40 and even s 50 ng / cm2 per hour measured at pH 6.9 (always

especially measured on silica).

  They generally also have a dissolution rate of at least 60, in particular at least 80 ng / cm2 per hour measured at pH 4.5 and / or a dissolution rate of at least 40 ng / cm2, in particular of at least ng / cm2 per hour measured at pH 6.9 and / or measured at pH 7.5 (in particular measured on silica). They are mainly used to make thermal and / or acoustic insulation products or soilless growing substrates. The subject of the invention is also all products comprising at least in part the

  mineral wools defined above.

  Other details and advantageous features emerge from the

  description below of preferred nonlimiting embodiments.

  Table 1 below groups the chemical compositions, in

  weight percentages from fifteen examples.

  When the sum of all the contents of all the compounds is slightly less than 100%, it is to be understood that the residual level corresponds to the non-analyzed impurities / minor components, rate of at most 0.5% to 1% and / or is only due to the approximation accepted in this

  domain in the analysis methods used.

  EX. 1 EX. 2 EX. 3 EX. 4 EX. 5 EX. 6 EX. 7 EX. 8

  SiO2 45.1 43.7 42.2 40.6 42.0 41.2 45.4 42.7

  A1203 18.1 19.9 21.7 23.5 18.3 17.0 17.4 18.5

  Fe203 6.3 6.5 6.8 7.2 8.8 0.7 5.7 5.4 CaO 13.9 13.7 13.5 13.3 11.0 21.0 14.8 17.6 MgO 13.0 12.7 12.3 11.9 12.0 18.5 13.3 14.6 Na2O 1.9 1.9 1.8 1.7 2.6 0.1 1.8 1.7

  K20 0.5 0.5 0.4 0.40 1.6 0.3 0.4 0.4

P205 0.1 0.1 0.1 0.1 0.5 0 0 0

  TiO2 0.6 0.7 0.8 0.9_ 2.6 0.8 0.8 0.7 MnO 0.2 0.2 0.2 0.2 0.2 0.1 0.2 0.2

SO3 0.2 0.2 0.2 0.2 0.3 0.3 0.1 0.1

  Total 100 100 100 100 100 100 100 100 CaO + MgO (RO) 26.9 26.4 25.8 25.2 23 39.0 28.0 32 Na2O + K20 (R20) 2.4 2.4 2.2 2.1 4.2 0.4 2.2 2.1 MgO / CaO 0.93 0.93 0.91 0.89 1.09 0.88 0.9 0.83

  R20 / AI203 0.13 0.12 0.10 0.09 0.23 0.02 0.13 0.13

TABLE 1 Pl OD CD

  EX. 9 EX. 10 EX. 11 EX. 12 EX. 13 EX. 14 EX. 15

  SiO2 44.8 42.8 41.5 42.9 41.8 41.0 40.8

  A1203 17.9 20 22.1 20.1 21.2 22.2 22.8

  Fe203 7.7 8 8.6 8.2 8.5 8.4 8.8 CaO 13.3 13.2 12.6 12.9 12.7 12.8 12.3 MgO 13.2 12.9 12 , 3 12.7 12.5 12.4 12 Na2O 1.9 1.8 1.7 2 2 1.9 2.0

K20 0.4 0.4 0.4 0.4 0.4 0.4 0.4

  P205 0.05 0.05 0.05 0.06 0.06 0.05 0.06

  TiO2 0.5 0.6 0.7 0.6 _0.7 0.7 0.7 MnO 0.18 0.2 0.2 0.2 0.2 0.2 0.2

S03 - _.__ _ _ _

  Total 99.9 99.9 100.1 100.1 100.1 100.1 100.1 CaO + MgO (RO) 26.5 26.1 24.9 25.6 25.2 25.2 24.3 Na20 + K20 (R20) 2.3 2.2 2.1 2.4 2.4 2.3 2.4 MgO / CaO 0.99 0.98 0.98 0.98 0.98 0.97 0.98

  R20 / AI203 0.13 0.11 0.10 0.12 0.11 0.10 0.1

  TABLE 1 (continued) o on The compositions according to these examples were fiberized by centrifugation

  external, in particular according to the teaching of the aforementioned patents.

  Their working levels, defined by the Tiog 1 - Tliq difference, are

largely positive.

  All have an MgO / CaO ratio greater than 0.8 and even greater than 0.85 and a very moderate P205 level (less than 1%) or zero. They also all have a high alumina level of around 17 to 23%. All of the examples except Example 6 have an Fe 2 O 3 content of around 6 to 8%. Example 6, with very little iron and a lot of alkaline earth oxides, makes it possible to

  make "white" rock wool mentioned above.

  Their biodegradability, in particular measured at neutral pH or weakly

  acid (pH 6.9 or 7.5), or at acidic pH (4.5) is satisfactory.

  Table 2 below groups together the results of the speed of dissolution of the silica in the mineral wools according to Examples 9, 10 and 11, noted "KSio2" and expressed in ng / cm2 and per hour: - according to an in vitro test in a fluid buffered at acidic pH (4.5), denoted "acidic fluid", - according to an in vitro test in a fluid buffered at pH approximately 7.4 to 7.5,

noted "neutral fluid".

ACID FLUID NEUTRAL FLUID

  K SiO2 (EX. 9) 35 32 K SiO2 (EX. 10) 58 45 K SiO2 (EX. 11) 83 52

TABLE 2

  From these results, it seems to emerge that the more the alumina content increases, the more the speed of dissolution is increased at acid pH

  and, to a lesser extent, also at neutral pH.

Claims (16)

  1. Mineral wool capable of dissolving in a physiological medium, characterized in that it comprises the following constituents according to the following weight percentages: SiO2 38-46%, in particular at least 40% A1203 16-24%   MgO 10-20% RO (CaO + MgO) 16-40% MgO / CaO> 0.8 R20 (Na2O + K20)> 0.3% P25Os 0-5% Fe203 (total iron)> 0.5% TiO2 0 -3% MnO 0-2% S03 0-2%   2. Mineral wool according to claim 1 characterized in that it comprises oxides RO (CaO + MgO) according to the following weight percentages: RO 18-32% or more from 32% up to 40%   3. Mineral wool according to one of the preceding claims   characterized in that it comprises Fe203 (total iron) according to the following weight percentages: 0.5 to 1.7% or more than 1.7 up to 12%   4. Mineral wool according to one of the preceding claims   characterized in that it comprises oxides R20 (Na20 + K20) according to the following percentages: 0.3 to 1%, or more than 1% up to 6%, in particular at least 2 or 2.2%   5. Mineral wool according to one of the preceding claims   characterized in that it respects the relationship: MgO / CaO> 0.85 preferably> 0.95, in particular> 1 or> 1.15   6. Mineral wool according to one of the preceding claims,   characterized in that it respects the relationship: R20 / A1203 0.07-0.8, preferably 0.09 to 0.3   7. Mineral wool according to one of the preceding claims   characterized in that it comprises from 0 to 0.1% by weight of P205, or more than 0.1% up to 2 or 3%.   8 - Mineral wool according to one of the preceding claims   characterized in that it comprises MnO, in particular from 0.1 to 4%   and / or B203, in particular from 0.1 to 5%.   9. Mineral wool according to one of the preceding claims   characterized in that it comprises MgO according to the following weight percentages:   MgO> 11%, especially <19%, preferably between 12 and 15%.   10. Mineral wool according to one of the preceding claims   characterized in that it comprises CaO according to the following percentages: CaO <22%, in particular> 10%, preferably between 11 and 18% or more 18% to 21%.   11. Mineral wool according to one of the preceding claims,   characterized in that it comprises A1203 according to the following percentage: A1203> 18.5%, in particular> 19% or> 20%   12. Mineral wool according to one of the preceding claims,   characterized in that it has a dissolution rate of at least ng / cm2 per hour measured at pH 4.5 and a dissolution rate of at least   minus 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 of at least ng / cm2 per hour measured at pH 4.5 and a dissolution rate of at least   minus 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 13 of at least 40 ng / cm2 per hour measured at pH 7, 5 and / or a speed of   dissolution of at least 40 ng / cm2 per hour measured at pH 6.9. 15. Mineral wool according to one of the preceding claims, characterized in that it is obtained by external centrifugation.   16. Thermal and / or acoustic insulation product or above-ground growing medium comprising at least partly mineral wool according to   one of the preceding claims.