EP0994648A1

EP0994648A1 - Biodegradable mineral wool composition

Info

Publication number: EP0994648A1
Application number: EP99916985A
Authority: EP
Inventors: Alain Debouzie; Jean-Luc Bernard; Fabrice Lafon; Alain De Meringo
Original assignee: Saint Gobain Isover SA France
Current assignee: Saint Gobain Isover SA France
Priority date: 1998-05-06
Filing date: 1999-05-04
Publication date: 2000-04-26
Also published as: FR2778400A1; ZA200000071B; WO1999056526A1; AU3527599A; NO20000029D0; JP2002512817A; HUP0002499A2; AR015287A1; SK188999A3; BR9906422A; HRP20000009A2; CA2295870A1; IS5326A; PL337923A1; CN1273505A; NO20000029L; TR200000072T1

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 WITH BIODEGRADABLE CHARACTER

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 substrates.

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

Conventionally, this type of mineral wool can be fiber by so-called "external" centrifugation processes, for example of the type of those using a cascade of centrifugation wheels fed with molten material by a static distribution device, as described in particular in the patents EP-0 465 31 0 or EP-0 439 385.

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 in 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 at reconciling a biodegradable character with an ability to be fiberized by external centrifugation (without excluding however other fiberizing modes). 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:

SiO ₂ 38-46%, especially at least 40%

AI ₂ O ₃ 1 6-24%

RO (CaO and / or MgO) 1 6-40%

MgO 10-20%

MgO / CaO> 0.8 (or> 0.70 in particular> 0.75)

R ₂ O (Na ₂ O and / or K ₂ 0)> 0.3% P ₂ O ₅ 0-5%

Fe ₂ O ₃ (total iron)> 0.5%

TiO ₂ 0-3%

MnO 0-2%

SO ₃ 0-2%

(Throughout the rest of the text, any percentage of a constituent of the composition must be understood as a weight percentage).

The selection of such a composition has made it possible to combine a whole series of advantages, in particular by playing on the multiple, complex roles played by a certain number of its specific constituents.

Thus, it is indeed a mineral wool composition of the rock type: its level of alkaline oxides (R ₂ O) essentially in the form Na ₂ 0 and / or K ₂ 0 is moderate or even very low, generally less 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 22%. The possible contents of MnO, Ti0 ₂ and S0 ₃ are rather to be considered as contents of impurities frequently encountered in this family of compositions: generally there is up to 3% in overall content of impurities in the compositions.

The fiber viscosity of such a composition is suitable for external centrifugation.

As for the biodegradable character, it was already known that certain compounds made it possible to improve it considerably in compositions. of the rock type in particular, such as P ₂ 0 ₅ , 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-0 459 897 and WO93 / 22251. However, a massive addition of P ₂ 0 ₅ has not proven to be the most judicious route in the context of the invention. Indeed, other considerations, for example economic, (P ₂ 0 ₅ coming from expensive raw materials) and also technical considerations may intervene: changes in the proportions of P ₂ O ₅ , and for example of alumina, in the composition may vary other properties in an undesirable or unknown sense. Thus, P ₂ O ₅ 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 control.

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 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 these data, essentially in the following manner: the composition may contain P ₂ O ₅ , 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 P ₂ 0 ₅ or even without P ₂ O ₅ at all (or any other very particular compound assumed to be favorable to biodegradability), by another means, which has consisted, in particular, in to play on the relative proportion in MgO compared 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 report, we managed to reach the high level of biodegradability which until now could only be obtained with high P ₂ 0 ₅ contents in order to "compensate" for significant alumina and / or iron contents. Note a non-negligible subsidiary advantage linked to a low P ₂ 0 _{5 level} : too much P ₂ 0 ₅ 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 previously seemed to be favorable to rapid dissolution at an 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 retain its beneficial effect at acidic pH without being penalizing at neutral pH.

Note that the sum Si0 ₂ + AI ₂ O ₃ makes it possible to regulate for a large part the viscosimetric behavior of the compositions and that it is preferably at least 58%, in particular 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) either between 1 8 and 32%, or more than 32% up to 40%, for example between 26 and 30%.

Similarly, the iron contents Fe ₂ 0 ₃ 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 referred to as "white wool", used in particular for applications of mineral wool by spraying on building elements.

According to a second variant, the iron content is higher, with in particular more than 1.7% up to 12% in Fe ₂ 0 ₃ , and preferably from 5 to 10% or from 5 to 8% Fe ₂ 0 ₃ (generally combined with an RO content of 1 8 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 felts. Advantageously, the content of oxides R ₂ 0 (Na ₂ 0 and / or K ₂ 0) can be either between 0.3 and 1% (preferably with a view to manufacturing the white wool mentioned above), or higher, in particular from more than 1% to almost 6%, for example from at least 2 to 2.2% or between 1 and 3%.

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, 1 5, and generally at least plus 2 or 3. The advantageous effect mentioned above is thus obtained, without too great an excess of MgO relative to CaO making the supply of raw materials for these oxides too complicated or expensive. As mentioned above, it is also possible to use slightly lower ratios, for example with an MgO / CaO ratio of between 0.75 and 0.80.

Advantageously also, the compositions according to the invention can respect the relationship R ₂ O / AI ₂ O ₃ of between 0.07 and 0.8, preferably between 0.09 and 0.3 or between 0.05 and 0.2 .

The compositions according to the invention preferably have a P ₂ O _{5 content} of more than 0.1%, and in particular up to 2 to 3%. This moderate rate influences the biodegradability very advantageously, without penalizing the composition economically too much or influencing its liquidus temperature too much. According to another variant, the level of P ₂ 0 ₅ can be lower, in particular be zero or slightly higher up 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 TiO ₂ as impurities or added voluntarily, for example in a content up to 1 to 2%. SO ₃ is also to be considered as an impurity, just like P ₂ 0 ₅ when it is confined to values less than 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 1 0%, advantageously between 1 1 and 1 8% or more than 1 8 to 21%.

In parallel, the preferential level of MgO of the composition is preferably at least 11% and generally at most 19%, the preferred range being between 12 and 15%.

According to a preferred nonlimiting embodiment of the invention, the alumina Al ₂ 0 _{3 content} of the compositions is at least 18.5%, in particular at least 19%, and even at least 20 or 21 %.

The difference T, _ogl - T _q 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, it is that is to say the range of temperatures in which they can be fiberized, by external centrifugation in particular.

Mineral wools, as mentioned above, exhibit a satisfactory level of biosolubility, whether the measurement method involves a neutral, slightly basic pH, or an 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 / cm ² 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 / cm ² 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 / cm ² per hour measured at pH 6.9 (always in particular measured on silica). They generally also have a dissolution rate of at least 60, in particular at least 80 ng / cm ² per hour measured at pH 7.5 and / or a dissolution rate of at least 40 ng / cm ² , in particular at least

60 ng / cm ² 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 characteristics will emerge from the description below of preferred nonlimiting embodiments.

Table 1 below groups together the chemical compositions, in weight percentages, of fifteen examples.

When the sum of all the contents of all the compounds is slightly less than 1 00%, it should be understood that the residual level corresponds to the non-analyzed impurities / minority components, a level of at most 0.5% to 1% and / or is only due to the approximation accepted in this area in the analysis methods used.

SO SO ϋi

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

SiO ₂ 45.1 43.7 42.2 40.6 42.0 41.2 45.4 42.7

A12O3 18.1 19.9 21.7 23.5 18.3 17.0 17.4 18.5

Fe ₂ O ₃ 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

Na ₂ O 1.9 1.9 1.8 1.7 2.6 0.1 1.8 1.7

K ₂ O 0.5 0.5 0.4 0.40 1.6 0.3 0.4 0.4

P2O5 0.1 0.1 0.1 0.1 0.5 0 0 0

TiO 0.6 0.7 0.8 0.9 2.6 0.8 0.8 0.7 œ

MnO 0.2 0.2 0.2 0.2 0.2 0.1 0.2 0.2

SO ₃ 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

Na., 0 + K ^ O (RjO) 2.4 2.4 2.2 2.1 4.2 0.4 99 2.1

MgO / CaO 0.93 0.93 0.91 0.89 1.09 0.88 0.9 0.83

R2O / AI2O3 0.13 0.12 0.10 0.09 0.23 0.02 0.13 0.13

TABLE 1 n

H ve B o

O Ut

9 \

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

SiO ₂ 44.8 42.8 41.5 42.9 41.8 41.0 40.8 as

(Λ

AI2O3 17.9 20 22.1 20.1 21.2 22.2 22.8 Bone

Fe ₂ O ₃ 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

Na ₂ O 1.9 1.8 1.7 2 2 1.9 2.0

K ₂ O 0.4 0.4 0.4 0.4 0.4 0.4 0.4

P2O5 0.05 0.05 0.05 0.06 0.06 0.05 0.06

TiO ₂ 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

N / A ₃ - - - - - - -

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

Na ₂ 0 + K2O (R ₂ 0) 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 R2O / AI2O3 0.13 0.11 0.10 0.12 0.11 0.10 0.1

TABLE 1 (continued)

• n / A

H so

Ut as

The compositions according to these examples were fiberized by external centrifugation, in particular according to the teaching of the aforementioned patents.

Their working stages, defined by the difference T, _og , - T _hq , are largely positive.

All have an MgO / CaO ratio greater than 0.8 and even greater than 0.85 and a very moderate level of P ₂ 0 ₅ (less than 1%) or zero. They also all have a high alumina level of about 17 to 23%. All the examples apart from example 6 have an Fe ₂ O _{3 content} around 6 to 8%. Example 6, with very little iron and a lot of alkaline earth oxides, makes it possible to manufacture “white” rock wool mentioned above.

Their biodegradability, in particular measured at neutral or weakly acidic pH (pH 6.9 or 7.5), or at acidic pH (4.5) is satisfactory.

Table 2 below groups together the results of measurements of the speed of dissolution of silica in mineral wools according to examples 9, 10 and 11, denoted "K _{S | 02} " and expressed in ng / cm ² and per hour:

* - * ^• according to an in vitro test in a fluid buffered at acidic pH (4, 5), noted "acidic fluid",

"→ according to an in vitro test in a fluid buffered to a pH of approximately 7.4 to 7.5, noted" neutral fluid ".

ACID FLUID NEUTRAL FLUID

K _Sl02 (EX. 9) 35 32

K _Sl02 (EX. 1 0) 58 45

K _S , ₀₂ (EX. 1 1) 83 52

TABLE 2

From these results, it seems to emerge that the more the alumina content increases, the more the dissolution rate is increased at acidic pH and, to a lesser extent, at neutral pH as well.

Two examples of additional compositions 1 6 and 1 7 also proved to be interesting, respecting the formulation described above with an MgO / CaO ratio of 0.75.

The compositions are detailed in Table 3 below with the same concentrations as in Table 1: 11

EXAMPLE 16 EXAMPLE 17

SiO ₂ 42 42

AI ₂ O ₃ 19 22

CaO 16 16

MgO 12 12

Na ₂ 0 0.5 1

K ₂ O 2 0.5

Fe ₂ O ₃ 7.5 5.7

Total 99 99.2

CaO + MgO 28 28

Na ₂ O + K ₂ O 2.5 1.5

MgO / CaO 0.75 0.75

R ₂ O / AI ₂ O ₃ 0.13 0.07

TABLE 3

Claims

1. Mineral wool capable of dissolving in a physiological medium, characterized in that it comprises the following constituents according to the following weight percentages:

SiO ₂ 38-46%, especially at least 40%

AI2O3 16-24%

MgO 10-20%

RO (CaO + MgO) 16-40%

MgO / CaO> 0.8

R2O (Na ₂ O + K ₂ O)> 0.3%

P2O5 0-5%

Fe ₂ O ₃ (total iron)> 0.5%

TiO ₂ 0-3%

MnO 0-2%

SO ₃ 0-2%

2. Mineral wool according to claim 1 characterized in that it comprises RO oxides (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 Fe2θ3 (total iron) according to the following weight percentages:

0.5 to 1.7% or more than 1.7 to 12%

4. Mineral wool according to one of the preceding claims, characterized in that it comprises oxides R2O (Na ₂ O + K ₂ O) 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:

R2O / AI2O3 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 P ₂ O ₅ , 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 B2O3, 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> 1 1%, 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%.

1 1. Mineral wool according to one of the preceding claims, characterized in that it comprises AI2O3 according to the following percentage:

AI2O3> 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 30 ng / cm ² per hour measured at pH 4.5 and a dissolution rate of at least 30 ng / cm ² 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

30 ng / cm ² per hour measured at pH 4.5 and a dissolution rate of at least 30 ng / cm ² 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 / cm ² per hour measured at pH 4.5 and / or a dissolution rate of at least minus 40 ng / cm ² per hour measured at pH 7.5 and / or a dissolution rate of at least 40 ng / cm ² 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. A thermal and / or acoustic insulation product or an above-ground culture substrate comprising at least partly the mineral wool according to one of the preceding claims.