AU762595B2

AU762595B2 - Biodegrable mineral wool composition

Info

Publication number: AU762595B2
Application number: AU35273/99A
Authority: AU
Inventors: Jean-Luc Bernard; Alain De Meringo; Fabrice Laffon
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: 2003-06-26
Anticipated expiration: 2019-05-04
Also published as: CN1273504A; NO20000030L; DE69928892T2; HUP0002448A2; WO1999056525A1; EP0994647A1; KR20010021517A; EP0994647B1; SK285275B6; RU2254301C2; SK189199A3; HUP0002448A3; JP2002512937A; PL190138B1; FR2778399A1; KR100732868B1; PL337878A1; CA2295868C; ATE312506T1; CA2295868A1

Description

S

MINERAL WOOL COMPOSITION The present invention relates to the field of artificial mineral wool. It is aimed more particularly at mineral wool intended for manufacturing thermal and/or acoustic insulation materials or soilless-culture substrates.

It concerns more particularly mineral wool of the rock-wool or basalt-wool type, that is to say the chemical compositions of which involve a high liquidus temperature and a high fluidity at their fiberizing temperature.

Conventionally, this type of mineral wool is fiberized by so-called "external" centrifuging processes, for example of the type of those using a cascade of centrifuging wheels fed with molten material by a static delivery device, as described in particular in Patents EP-0,465,310 or EP-0,439,385.

The process of fiberizing by so called "internal" centrifuging, that is to say using centrifugers rotating at high speed and drilled with holes, is on the other hand conventionally reserved for fiberizing mineral wool of the glass-wool type, broadly having a composition richer in alkali metal oxides, a lower liquidus temperature and a higher viscosity at the fiberizing temperature than rock wool or basalt wool. This process is, for example, described in Patents EP-0,189,354 or EP-0,519,797.

However, technical solutions have recently been developed which allow the internal centrifuging process to be adapted for fiberizing rock wool or basalt wool, especially by modifying the composition of the material of which the centrifugers are composed and their operating parameters. For more details on this subject the reader may refer in particular to Patent WO 93/02977. This adaptation has proved to be particularly beneficial in that it makes it possible to combine properties which hitherto were not inherent in either of the two types of wool rock or glass. Thus, the rock wool obtained by internal centrifuging is comparable in quality to that of glass wool, with a lower unfiberized content than that of rock wool obtained conventionally. However, it retains the two key aspects associated with its chemical nature, namely a low chemicals cost and a very high fire resistance.

There are therefore two possible ways of fiberizing rock or basalt wool, the choice of one or the other depending on a number of criteria, including the required level of quality with regard to the intended application and that of industrial and economic feasibility.

To these criteria have been added in recent years that of biodegradability of mineral wool, namely its ability to be rapidly dissolved in a physiological medium, so as to prevent any potential pathogenic risk associated with the possible accumulation of the finest fibres in the body by inhalation.

The object of the invention is therefore to improve the chemical composition of mineral wool of the rock or basalt type, the improvement being aimed especially at increasing its biodegradability and/or at reconciling biodegradability with ability 15 to be fiberized by internal centrifuging (without, however, excluding other fiberizing methods).

According to the present invention, there is provided mineral wool capable of being dissolved in a .i physiological medium, including constituents below the following percentages by weight: o* SiO 2 38-52%, SA1 2 0 3 17-23%, S* 'Si0 2 +A1 2 0 3 56-75%, RO(CaO+MgO) 9-26%, MgO 4-20%, MgO/CaO >0.8,

R

2 0 (Na 2 0+K 2 0)

P

2 0s Fe 2 0 3 (total iron)

B

2 0 3 MnO 0-4%, Ti02 0-3%, wherein the mineral wool satisfies the relationship 0.2

R

2 /A1 2 0 3 <0.8.

2a The subject of the invention is a mineral wool capable of being dissolved in a physiological medium, which comprises the constituents below in the following percentages by weight: SiO 2 38 52%, preferably 40 48% A1 2 0 3 17-23% SiO 2 A1 2 0 3 56 preferably 62 72% RO (CaO and/or MgO) 9 26%, preferably 12 MgO 4 20%, especially 7 16% MgO/CaO 0.8, preferably 2 1.0 or 2 1.15

R

2 0 (Na20 and/or K 2 0) 22%

P

2 0 5 0 Fe 2 0 3 (total iron) preferably 2% MnO 0 4%

B

2 0 3 0 TiO 2 0- 3% It may also furthermore comprise, preferably, Fe 2 03 (total iron) and P 2 0s contents such that: H: \mboarke\Keep\Speci\35273-99 SPECI.doc 20/08/02 1 Fe 2 0 3 (total iron)/ P 2 0 5 20 when P 2 0 5 (Throughout the rest of the text, any percentage of a constituent of the composition should be understood to mean a percentage by weight and the compositions according to the invention may include up to 2 or 3% of compounds to be regarded as unanalysed impurities, as is known in this type of family of compositions).

The selection of such a composition has allowed a whole raft of advantages to be built up, especially by varying the many complex roles that a number of its specific constituents play.

Thus, what is involved is a mineral wool composition of the rock wool type, in which its content of alkali metal oxides (R 2 0) essentially in the form of Na 2 0 and/or K 2 0 is modest, less than 12 or even less than 10 or even At the same time, its content of alkaline-earth metal oxides essentially in the form of CaO and/or MgO, is relatively high, at least 9% and even more at least 12% or even 16%. The iron oxide content (measured in the form of Fe 2 0 3 but, by convention, corresponding to the total iron content) was set at a relatively significant level of at least 1.7% and even more of at least Such a content present in the composition is most particularly justified when the composition has to be fiberized by internal centrifuging, as it was observed that this made it possible to slow down the rate of corrosion of the materials of which the centrifuger is composed.

Manganese oxide MnO could in particular play a similar role this is why the composition may optionally contain a few percent of MnO.

Moreover, the viscosity at fiberizing of such a composition may be high enough for internal centrifuging and it may be termed a "hard rock" composition, this being due in particular to a suitable silica and alumina content.

As regards its biodegradability, it was already known that, especially in compositions of the rock-wool type, certain compounds, such as P 2 0 5 could considerably improve this, while other oxides seemed on the contrary to have a tendency to reduce it, at the very least in neutral pH. Reference may be made, for example, to Patents EP-0,459,897 and WO 93/22251. However, a massive addition of P 2 0 5 has not proved in the context of the invention to be the most judicious approach. This is because other considerations may arise, for example economic ones (P 2 0 5 coming from expensive raw materials) and also technical ones the changes in the proportions of P 2 0 5 and especially of alumina, in the composition may cause other of its properties to vary in an undesirable or It unknown manner. Thus, P 2 0 5 is not without influence on the viscosity of the composition, just like alumina. However, most particularly in the case of compositions of the rock-wool type to be fiberized by internal centrifuging, to which the invention applies most advantageously, the viscosimetric behaviour of the composition is a very critical and important criterion to be controlled and regulated sufficiently.

Moreover, certain compounds may be advantageous for certain properties but be unfavourable for obtaining a high degree of biodegradability, something that seems to be the case with iron, which is advantageous, as mentioned above, for prolonging the life of centrifugers but which could tend to reduce the biodegradability of rock wool, or the case with alumina, which is judicious for regulating the viscosity of the composition but may not be very favourable with regard to biosolubility, especially when measured by in vitro tests in neutral pH.

The invention has therefore established a judicious compromise between all this data, essentially in the following manner: the composition may contain

P

2 0 5 but in a modest amount of at most or rather at most It also contains iron oxide, which is advantageous, but for reasons other than biodegradability. However, the composition achieves a high level of biodegradability without adding an excessive amount of P 2 0 5 (or any other very special compound regarded as being favourable to biodegradability), by another means, which consisted, in particular, in varying the relative proportion of MgO with respect to CaO. In fact, compositions of the rock-wool type generally contained a proportion of lime CaO which is greater than that of magnesia MgO.

By reversing this ratio, it has been found that the high level of biodegradability hitherto only able to be obtained with high P 2 0 5 contents, in order to "compensate" for the significant alumina and iron contents, could be achieved. A subsidiary, and not insignificant, advantage associated with a low P 2 0 5 content should be noted, namely too much P 2 0 5 tends in fact to increase the liquidus temperature of the composition, which is obviously not favourable for fiberizing by internal centrifuging.

Another characteristic aspect according to the invention relates to the combination of this particular MgO/CaO ratio with a rather high alumina content, since this is at least 17%. It has been found that this combination allowed the biosolubility criteria, both measured in in vitro tests in neutral pH and in in vitro It tests in acid pH, to be satisfactorily met. Indeed, the matter of knowing which pH was most representative of the in vivo physiological medium, especially that of pulmonary regions, has not been definitively resolved. A high alumina content has seemed until now to be favourable to rapid dissolution in acid pH, but weakly/slowly in 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 alumina content but by adapting the content of alkaline-earth metal oxides so as to maintain its beneficial effect in acid pH without being made to suffer in neutral pH.

It should be noted that the sum SiO 2 A1 2 0 3 allows the viscosimetric behaviour of the compositions to be largely controlled.

According to one embodiment of the invention, the compositions satisfy the relationship:

R

2 0/A1 2 0 3 between 0.2 and 0.8.

The content of alkali metal oxides R 2 0, i.e. essentially Na 2 0 and/or K 2 0, is preferably at least 5% and especially maintained within ranges of about 5 to 12% (or possibly 13%).

As regards the content of iron oxide(s) (total iron), as mentioned above, it is advantageous to provide at least and even at least of iron oxides in order to protect the centrifugers, especially between 5 and Furthermore, the iron oxides may have a favourable effect on the fire resistance of the mineral wool obtained.

Advantageously, the compositions according to the invention also satisfy the following relationship, expressed as a ratio of percentages by weight: MgO/CaO between 1 and 3. Thus, the abovementioned advantageous effect is obtained without too great an excess of MgO with respect to CaO making it excessively complicated or expensive to procure these oxides as raw materials.

The compositions according to the invention preferably have a P 2 0 5 content of at least 0.5 or of at least and especially of about 1.5 to This moderate content has a highly advantageous influence on the biodegradability, without economically penalizing the composition too much or having too great an influence on its liquidus temperature.

According to another embodiment, the P 2 0 5 content may be lower, especially from 0% or, for example, from 0.1 to 0.5% or from 0.1 to 1%.

The preferred CaO content of the composition of the invention is less than or equal to 15%, especially at least 2% and advantageously between 5 and 14%.

In parallel, the preferred MgO content of the composition is less than or equal to 20% and preferably at least the preferred range lying between 5 and 14%.

It may be considered that, apart from the optional P 2 0 5 the two compounds which have the greatest influence on the viscosity at fiberizing of the composition are silica and alumina. It is thus possible to select at least 60% of (SiO 2 A1 2 0 3

P

2 0 5 in order to guarantee a viscosity high enough for fiberizing by internal centrifuging, especially within values of between 60 and 70% and especially at least 61 or 62%.

The oxidation of the composition may, for example, be controlled by the addition of manganese oxide MnO.

Adding boron oxide, which remains optional may allow the thermal insulation properties of the mineral wool to be improved, especially by tending to lower its thermal conductivity coefficient in its radiative component. Optionally, the composition may also contain TiO 2 as impurities or intentionally added, for example in an amount up to 2%.

According to a non-limiting preferred embodiment, the alumina content of the compositions according to the invention is at least 18%, especially at least 19, or at least The difference Tlog2.5 Tliq is preferably at least 100C, preferably at least or 300C: this difference defines the "working range" of the compositions of the invention, i.e. the temperature range in which they may be fiberized, most particularly by internal centrifuging. The temperature at which the compositions have a viscosity equal to log 2.5 (in poises) [sic] is written as TIog2.5 and the liquidus temperature is written as Tliq.

The mineral wools, as mentioned above, have a satisfactory level of biosolubility, whether the measurement method involves a neutral or slightly basic pH or an acid pH.

Thus, the mineral wool according to the invention generally has a rate of dissolution of at least 30, and preferably at least 40 or 50 ng/cm 2 per hour measured at pH 4.5 and at least 30, preferably at least 40 or 50 ng/cm 2 per hour measured at pH In general, such mineral wool has a rate of dissolution of at least 30 and preferably at least 40 or at least 50 ng/cm 2 per hour measured at pH 4.5 and a rate of dissolution of at least 30 and preferably at least 40 or at least 50 ng/cm 2 per hour measured at pH 6.9.

In general, it also has a rate of dissolution of at least 60 and especially at least 80 ng/cm 2 per hour measured at pH 4.5 and/or a rate of dissolution of at least 40 and especially at least 60 ng/cm 2 per hour measured at pH 6.9 and/or a rate of dissolution of at least 40 and especially at least 60 ng/cm 2 per hour measured at pH The mineral wool is mainly used to manufacture thermal and/or acoustic insulation products or soilless-culture substrates. The subject of the invention is also any product comprising, at least partly, the mineral wool defined above.

Further details and advantageous characteristics will emerge from the description below of preferred non-limiting embodiments.

Table 1 below gives the chemical compositions, as percentages by weight, of seven examples.

When the sum of all the contents of all the compounds is slightly less than or slightly more than 100%, it is to be understood that the difference with 100% corresponds to the minor impurities/compounds (not analysed) and/or is due merely to the accepted approximation in the analytical methods used in this field.

T 1 1 T EX.1I EX. 2 EX. 3 EX. 4 EX. 5 EX. 6 EX. 7 SiO 2 42.7 45.8 42.1 44.9 42.4 48.0 42.7 A1 2 0 3 20.0 20.3 18.1 20.7 23.8 19.0 20.0 Fe 2

O

3 7.5 7.5 7.6 7.7 7.0 7.0 CaO 10.0 10.5 6.1 5.5 5.0 6.0 10.0 MgO 12.5 11.8 13.7 11.4 7.0 7.0 12.5 Na 2 O 5.0 5 11.3 7.1 8.0 8.0&

K

2 0 0.5 0.5 0.6 0.9 5.0 .5.0

B

2 0 3 0 0 0 0 0 0 0

P

2 0 5 0 0 0.02 0.04 0 0 0.6 TiO 2 1.8 0 0.6 1.9 1.8 -1.2 MnO 0 0 0.02 0.04 0 -0 Total 100 100 100.1 100.1 100 100 100 CaO MgO (RO) 22.5 22.3 19.8 16.9 12.0 13.0 22.5 Na 2

K

2 0 (R 2 0) 5.5 5.5 11.9 8 13.0 13.0 SiO 2 +A1 2 0 3

+P

2 0 5 63 66.1 60.2 65.6 66.2 67.00 63.6 MgO /CaO 1.25 1.12 2.25 2.04 1.40 1.17 1.25

ROIR

2 O 4.09 4.05 1.66 2.11 0.92 1 4.09 The compositions according to these examples were fiberized by internal centrifuging, especially according to the teaching of the aforementioned patent W093/02977.

Their working ranges, defined by the difference Tlog2.5 Tliq, are amply positive.

All the compositions have an MgO/CaO ratio of greater than 1 and a very modest (less than P 2 0 5 content and an iron oxide content of around 7% which has proved to be advantageous in limiting corrosion of the centrifugation dishes. They also have a high alumina content of approximately 18 to 20%, with a fairly high sum (SiO 2 A1 2 0 3 and an alkali metal oxide content of at least Their biodegradability, especially measured at neutral or slightly acid pH (pH 4.9 or or at acid pH is high.

The composition according to Example 7, which contains more than of P 2 0 5 satisfies the Fe203/P 2 05 ratio of between 1 and 20, here equal to 12.5, in accordance with a preferred embodiment of the invention.

For the purposes of this specification it will be clearly understood that the word "comprising" means "including but not limited to", and that the words "comprise" and "comprises" have a corresponding meaning.

It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents. forms part of the common general knowledge in the art, in Australia or in any other country.

Claims

1. Mineral wool capable of being dissolved in a physiological medium, including constituents below the following percentages by weight: Si0 2

38-52%, A1 2 0 3 17-23%, SiO 2 +A1 2 0 3

56-75%, RO(CaO+MgO) 9-26%, MgO 4-20%, MgO/CaO >0.8, R 2 0(Na20+K 2 0) P 2 0 5 Fe 2 03 (total iron) B 2 0 3 MnO 0-4%, TiO 2 0-3%, wherein the mineral wool satisfies the relationship 0.2 R 2 /A120 3 <0.8. 2. Mineral wool according to claim 1, in which the amount of Si0 2 is from 40-48%. 3. Mineral wool according to claim 1 or 2, in which the amount of SiO 2 +A1 2 0 3 is from 62-72%. 4. Mineral wool according to any preceding claim, in which the amount of RO(CaO+MgO) is from 12-25%. Mineral wool according to any preceding claim, in which the amount of MgO is from 7-16%. 6. Mineral wool according to any preceding claim, wherein the ratio of MgO/CaO is 7. Mineral wool according to any preceding claim, wherein the ratio of MgO/CaO is 1.15. 8. Mineral wool according to any preceding claim, wherein the amount of Fe 2 0 3 (total iron) is 2%. 9. Mineral wool according to any preceding claim, in which the Fe20 3 (total iron) and P 2 0s contents are such that: H:\wbourke\Keep\Speci\35273-99 SPECIdoc 20/08/02 11 1 Fe 2 0 3 (total iron)/ P 2 0 5 20 when P 2 0 5 Mineral wool according to any one of the preceding claims, in which it satisfies the relationship: R 2 0 11. Mineral wool according to claim 10, which satisfies the relationship R 2 0 is from 5-12%. 12. Mineral wool according to any one of the preceding claims, in which it satisfies the relationship: 1 MgO/CaO 3. 13. Mineral wool according to any one of the preceding claims, including at least 0.5% by weight of P 2 0 5 14. Mineral wool according to claim 13, wherein the amount of P 2 0s is at least 1% by weight. 15. Mineral wool according to claim 13 or 14, wherein the amount of P 2 0s is from 1.5-4% by weight. 16. Mineral wool according to any one of the preceding claims, wherein the amount of MgO is 20% by weight. 17. Mineral wool according to claim 16, wherein the amount of MgO is 7%. 18. Mineral wool according to claim 16 or 17, wherein the amount of MgO is between 7-13%. 19. Mineral wool according to any one of the preceding claims, wherein the amount of CaO is 15% by weight. Mineral wool according to claim 19, wherein the amount of CaO is 2%. 21. Mineral wool according to claim 19 or 20, wherein the amount of CaO is from 5-14%. 22. Mineral wool according to any one of the preceding claims, including at least 4% by weight of Fe 2 03 (total iron). 23. Mineral wool according to claim 22, wherein the amount of Fe20 3 (total iron) is at least 5% by weight. 24. Mineral wool according to claim 22 or 23, wherein H:\mbourke\Keep\Speci\35273-99 SPECI.doc 20/08/02 12 the amount of Fe 2 O 3 (total iron) is from 5-9% by weight. Mineral wool according to any one of the preceding claims, including in percentages by weight, the compounds SiO 2 A1 2 0 3 and P 2 0 5 in proportions such that: SiO 2 A1 2 0 3 P 2 0 5 is at least 26. Mineral wool according to claim 25, wherein the amount of SiO 2 +Al 2 0 3 +P 2 0 5 is from 60-70%. 27. Mineral wool according to any one of the preceding claims, including A1 2 0 3 in the following percentage by weight: A1 2 0 3 18%. 28. Mineral wool according to claim 27, in which the amount of A1 2 0 3 is 19%. 29. Mineral wool according to claim 27 or 28, wherein the amount of A1 2 0 3 is Mineral wool according to any one of the preceding claims, having a rate of dissolution of at least ng/cm 2 per hour measured at pH 4.5 and a rate of dissolution of at least 30 ng/cm 2 per hour measured at pH 31. Mineral wool according to any one of the preceding claims, having a rate of dissolution of at least ng/cm 2 per hour measured at pH 4.5 and a rate of dissolution of at least 30 ng/cm 2 per hour measured at pH 6.9. 32. Mineral wool according to any one of the preceding claims, having a rate of dissolution of at least ng/cm 2 per hour measured at pH 4.5 and/or a rate of dissolution of at least 40 ng/cm 2 per hour measured at pH 7.5 and/or a rate of dissolution of at least 40 ng/cm 2 per hour measured at pH 6.9. 33. Mineral wool according to any one of the preceding claims, which is obtained by internal centrifuging. 34. Thermal and/or acoustic insulation product or soilless-culture substrate, including at least partly, the mineral wool according to any one of the preceding claims. H:\mbourke\Keep\Speci\35273-99 SPECIdoc 20/08/02 13 Mineral wool capable of being dissolved in a physiological medium substantially as hereinbefore described with reference to any one of the foregoing examples. 36. Thermal and/or acoustic insulation product or soilless-culture substrate substantially as hereinbefore described with reference to any one of the foregoing examples. Dated this 20th day of August 2002 ISOVER SAINT-GOBAIN By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia H:\mbourke\Keep\Speci\35273-99 SPECI.doc 20/08/02