CA2165081A1 - Man-made vitreous fibre wool - Google Patents

Abstract

The production and physiological dissolution rate of mineral wool formed of MMV fibres containing 35-66 % SiO2, up to 10 % Al2O3, 10-45 % CaO, 2-30 % MgO, up to 10 % FeO, 0-7 % Na2O + K2O and 0-10 % TiO2 is improved by including both P2O5 and B2O3 in the composition.

Description

W095/29135 2 1 6 5 0 8 1 PCT~95/01414 ~a~-MAD~ VITREOU~ F~R~ ~nn~.
The pre ent invention relates to man-made vitreous fibre (MMVF) wool cont~i n~ ng iron and a relatively high amount of ~1k~ earth metals, and a low amount of ~1kA1i metals, ~o~vel~ionally known as stone, slag or basalt wool.
Various types of NMV fibres are known.
It is known, in the manufacture of traditional glass fibres, to include in the glass melt compon~nts which provide boron oxide (borate). This can improve the glass and the glass melt. However, borate _o~ n;ng raw materials are ~Yrç~ive and are normally not added at all if possible, esrec;~lly when the product contains iron and has low alkali and high AlkAline earth content, as in con~entional rock, stone and slag melts.
Glass wool products ~ l y have a relatively high content of ~lk~l ~ metal (often above 13% Na2O + KzO). In this specification all analyses are expressed by weight of total composition measured as oYi~PC- Glass filament and glass wool are ll~ lly free of iron but often also contain boron. Typically they contain less than 7% Al203. ~U_v~L
E-Glass is a filamentary or other no~l wool product and can have high aluminium and low or zero ~ 1 t metal. For instance JP-A-50090719 describes an E-Glass cont~;ning 15-16% Al203, 9.5-10.5% B2O3 and 5% PzO5~ It is free of iron and sodium.
Glass fibres are described in EP-A-9418 which can have a wide range of optionAl components ~nGl~ n~ inter alia, iron, boron and rh~sr~ous. None of the exemplified compositions contain both boron and rhOsrhQrous and they all have above 13% Al~Al~ metal oxide.
W093/07741 describes fibres contA;n;~g 0 to 4% P205, above 13% Na2O, and up to 8% Al203 for use in horticulture.
B203 can be ~ t but the total amount of impurities (including any B203 which is included) must be not above 1~.
Glass wool i8 described in EP-A-412878 which has high A~ met_l content (above 13%) and which contains borate.
It i~ free of iron. Ph~rho~ous is an optional component.

Wo95/29135 2 1 6 5 0 8 1 PCT~P9S/01414 It is included allegedly to improve solubility of the fi~res.
We are co~rned with improving the solubility of the fibres in those wools generally referred to as rock, stone, slag or basalt w0018 and which typically contain ~ron, a low amount of aluminium (below 10%), a low amount of AlkAl;
metal (below 7) and a significant amount of ~1k~l;ne earth metal (above 12%).
It has been ~r 0~ that it would be desirable to provide such wools in which the MMV fibres are soluble in a physiological medium, in particular lung fluid.
It is known that the composition of a fibre can significantly affect its solubility. For instance, it is illustrated in W087/05007 that fibres having a low alumina lS content, in particular alumina below 10% by weight of composition, have im~o~ed solubility in a physiological environment. It i8 ~lso known that inclusion of pho~rhorus can improve solubility in the physiological medium. This has been illustrated in the case of stone wool fibres in for instance EP-A-459,897. This discloses stone wool fibres which comprise 1 to 10% of phosphorus as P20s. This component îs said to provide solubility in the physiological medium. It can be ~ssumed that increasing the amount of ~hG~l.orous within this range increases solubility.
During the manufacture of NNVF wool the components which are to form the fibres are melted in a furnace, such as an electric, ~haft, tank or cupola furnace. This pro~n~efi a melt which ~ay then be fiberised. The melt ~ ly has a melting point of around 1,400 to 1,600C and is thus heated to above this temperature in the furnace.
It has been found that the inclusion o~ significant amounts of phosphorous in the melt can lead to some problems. For instance ~ho~r~rus may volatilj~e in the furnace, 1~A~
to difficulties of col-~-olling the composition. In par~ 5--1 Ar increasing the amount of phosF~orus can adversely influence melt viscosity and properties. It WO95t2~135 2 1 6 5 0 8 1 PCT~95/01414 increases the risk of the melt (which contains iron and little or no alkali metal and low aluminium) undergoing phase separation and cryætA~ tion. This leads to the for~ation and accumulation of solid or slag material in or on the apparatus being used for forming the melt and ~o"v~Ling the melt to fibres, and can cause increased amount of shot formation during the fibre-formation ~LGOeSS, re~l~c~ material efficiency and higher costs.
It would therefore be desirable to form NNVF wool having solubility characteristics of the type which would be expected in such wool from the use of relatively high phosphorus content while avoiding the manufacturing problems associated with relatively high phocrhorous contents.
These problems tend to increase as the content of phosphate in the melt increases. For instance difficulties may arise as the content of phosphate increases ~e~U~ld 5%.
It may be possible with some furnaces to use up to 10%
pho~phate but in general for ~LG~_Sing p~L~& ~ it i8 undesirable to inG~ more than thi~.
H~eV~, even at low levels of alumina, and in particular when it is not possible to provide a melt having very low levels of ~lumina, dissolution rates of the fibres are not as high as may be desirable at these levels of rhosrh~te.
Therefore it would be desirable to improve the solubility of MNV fibres in the physiological medium without the nc_- ity for using amounts of phosphate which lead to ~LG.-;~ing problems.
Fibres con~A ~ n i ng rhQsrhsrus and boron are mentioned in W094/23801, from which this application claims priority.
Accordinq to the invention there is provided MMVF wool formed of fibres formed from a composition comprising, by wei~ht of QYi ~C (with iron expressed as FeO):
SiO2 35-66%
Al203 up to 10%
CaO 10-45%

woss/2sl3s 2 1 6 5 0 8 1 PCT~95/0141 MgO 2-30%
FeO up to 10%
NazO + K20 0-7S
Tio2 0-10%
P205 + B2o~ and other elements - up to 20S
and which includes both P205 and B2C~.
We find surprisingly that the use of a phosphate- and boratc ~G~ n ~ nq melt can give fibres with adequate physiologi~al solubility pro~nce~ from a melt which has a combination of good processing, viscosity and temperature characteristics, especially when the amount of Al203 is low.
We find that an upper limit of lOS on the amount of phosphate assists in reducing manufacturing problems, especially phase separation. The amount is preferably 6%
or less and is ~ y below 5~. We find that inclusion of borate increases the physiological solubility of the fibres without the n~e~sity for using larger amounts of phosphate~ and allows the use of phosphate even in amounts below 5% whilst ret~i n ~ ng adequate physiological solubility. We also find that borate has the additional advantage that it im~Lov B the physical properties of the melt, in parti ~ r it assists in reducing the melting po$nt of the melt so that the risk of phase separation is re~- ~eA.
We also find that the use of boron in pho~rhQrus-cont~n~n~ fibres results in im~ ed fibre ~Lu~elLies.
For inst~nce tensile ~en~h, mo~ of elasticity and length to diameter ratio can be im~u~. Te~cile ~Lenyuh can be ~700 MPa. Fibre ~odulus of Elasticity can be <150 GPa. Length to fibre ratio can be >700, ~pec~ y when the fibre~ are made by a ~ Ae spinner.
The melt viscosity of the composition at 1400C is preferably 10-70 poise, preferably 15 to 30 poise.
The fibres preferably have a dissolution rate at pH
7.5 of at le~st 30nm/day, and preferably at least 50 or at least 60nm/day, when measured by the stationary set up ~ WO95/29135 2 1 6 5 0 8 1 PCT~P9S/01414 method described in Environmental Health Perspectives, Vol.
102, Supplement 5, October 1994, pages 83-86.
The wool of the invention may be provided in any known way. According to the invention we also provide ~ ~Gce-s of production of NMVF wool formed of fibres having a composition aO defined above, the process comprising providing raw materials to give the composition, providing a furnace, placing the raw materials in the furnace and heating them to a temperature between 1,400C and 1,600C to produce a melt, fiberising the melt, and collecting the fibres as a wool.
In this ~oce~s we find all the advantages in processing characteristics ~i~c~s~ above. Preferably the wool of the invention are made by this ~ oceOs of the invention.
In the ~LO~eoô of the invention the raw materials used to produce the melt may be any known raw materials which give the constituents of the composition. For instance, raw materials which may be used include ~i~h~r?, cement, clay, olivine sand, silica sand, waOte fo~,d~y sand, rasorite, colemanite and other bo~o.. _~nl~n;n~ materials, CG~ve~ Ler slag, blast-furnace slag, electric arc furnace slag~ iron oxide, waste stone wool, waOte asbestos, lime, soda, glass waste, dolomite, bauxite, iron silicate, kaoline, c~ m phosphate, quartz sand and other known melt ingredients.
The melt composition and hence the composition of the produced fibres preferably comprises at least 45%, often at least 47 or 48%, sio2. The amount is usually below 64 or 65%,preferably below 60~. Often the amount of sio2 is - from 53.5 to 64%.
The composition preferably has a low alumina content, generally below 6% and preferably below 4%. In general it is very ~Ype~ive to provide raw materials which contain no alumina at all, so Alz03 is present to some extent, usually in amounts of at least o.5~, al~holyh alumina amounts are generally kept as low as poæsible, preferably below 3 or 2~. Amounts of 1-4% are often suitable.
The composition ll~--A lly comprises at least 5%, generally at least 10% and preferably at least lS% ~ n~
earth metal Q~S (CaO and MgO). Generally the amount is not more than 50~. Preferably CaO is cont~ine~ in amounts of bet~ccn 10 and 35S. In some compositions amounts of 10-20% are preferred but in others amounts of 15 to 30% are preferred. MgO iæ usually present in an amount of at least 1%, often 5 to 20%, preferably 7 to 20%. For instance it may be in the range 5-15%.
The composition contains iron, and the amount is up to 10% by weight of total composition, measured a8 FeO.
Preferably iron is present in amounts o~ at least o.S or 1%. Amounts of up to 4% are often suitable but amounts may be up to 9 or 10%, e.g., in the range 6.5-9%.
The composition may comprise Alk~l~ metals (Na20 and K20) in amounts of 0% up to 6% or 7S. In general Na20 i8 present in amounts of 0% up to 4~ and R20 is present in amounts up to 2S. Usually e~ch is ~ t in an amount of at least 0.1%, but both are opt~on~l and can be omitted.
~ho~l~h~te i5 present in the composition, yen-rally in amounts of between O.S and 10%, measured a5 P20s, and often in the range 3 to 6%. For ~ o~e~sing ~uL~-e~ it is desirable to keep the amount of rhs~rh~te as low as possible whilst i.,~o~ ating ~nol~gh to give an adeguate dissolution effect. Pre~erably the ~ho~k~te amount i8 at least 0.5 but below 5S (e.g., up to 4.5%), more - preferably below 4%. US~11Y it is at least 2% or 3%~
Borate is il.~oL~GLated in useful amounts of up to 10%, measured as B2C~. The amount i8 preferably above 0.5 or 1~.
In general, e,~ l should be added to increase suitably the physiological dissolution rate, but i,.~oL~o~ation of large amounts of borate n~essitat~s the use of very ~Yr~ncive raw materials. Amounts of borate below 5% (e.g., 4.5 and ~ W095/29135 2 1 6 5 0 8 1 PCT~P95/01414 below) can give good results at economic cost but amounts up to 7 or 8% are sometimes preferred. The amount must be sufficient to give a useful effect and so is normally above 0.5 or 1% and preferably it is at least 3%. The amount of v 5 B203 is usually below the amount of P205 for re~ronc of economy.
Tio2 is optional. Tf present, its amount i8 ~ 1 ly 0.1 to 2%. The melt composition may addit;on~lly compri~e o to 20% of other ingredients, for instance BaO, ZnO, ZrO2, F2~ MnO, Li2o~ SrO. The total amount of other ingredients is usually not more than 5%, or at most 10%.
The composition of the melt and of the fibres particularly preferably comprises:
SiO2 45-64%, preferably 47-60 or 48-60%
Al203 0.5 to 4%
CaO 10-35~, MgO 5-20~, preferably 5-15 or 7-15 FeO 1-10%, preferably 1 to 9%
Na20 0 to 4%
X20 0 to 2%
Tioz o to 2%
P205 at least 0.5% but preferably below 5%
B2a~ at least 0.5% but preferably below 5%
other elements 0 to 5%
all percentages being by weight of total composition and iron Q~q being measured as FeO.
The raw materials are placed in a ft~rn~ce where they are heated to a temperature L~-ee.. 1,400C and 1,600C in order to produce a melt. In ye,.c al, they are heated to at 30 least 1,450C, preferably Letl_~...... 1,450 and 1,540C, y~ne~ally around l,480C to 1,520C.
The furnaces which can be used in the invention for forming the melt which is to be fiberised include cupola furnaces, oil and/or gas fired ~haft or tank furnaces or electric furnaces. In these furnaces the invention is part~c~ rly advantageous, al~ho?~h the composition also WO95/29135 2 1 6508 1 PCT~P95/01414 ~

shows advantages when using other known types of furnace.
Preferred furnaces are those in which significant amounts of air are drawn. Slag formation and any volat~ tion problems can be minimised by the invention.
The melt is fiberised in any known manner. In particular it may be fiberised by pouring into a fast-rotating cup having a substantially horizontal base and perforated side walls out of which iæ thrown as fi~res, or by pouring onto one or more Sp~nn~n~ wheels. The or each wheel is mounted on a separate horizontal axis. Melt poured onto the circumference of the spinning wheel is flung off as fibres. Although a single wheel can be used, preferably a c~c~ system is used in which the melt is poured onto the top rotor of a set of rotating rotors each mounted about a different substantially horizontal axis and arranged such that the melt is th~own from the top rotor onto the subseguent rotor, or on each --~h~equent rotor in sequence, in the set so as to throw mineral fibres off the or each subsequent rotor into a collection chamher. Any apparatus known for the fiberisation of mineral melts to form wool may be used but a particularly preferred apparatus is described in our patent publication W092/06047.
The fibres may then be collected as web or batt. The web may be cross-lArpe~ to form a batt. The batt may be consolidated into the desired MMVF wool product in known manner.
Binder i8 u5u~1ly included in the batt. For instance it may be sprayed into the fibres before they are collected as a web or batt.
The wool may be in ~he form of ~h~r~ batts or other elements or it may be in the form of tufts or granulates of mineral wool fibres, or in the form of art~cles made from such tufts or ganulates.
The MMVF wool may be used for any of the conventional ~u-~o~es of MMVF wool, for instance as a horticultural ~ WO95/29135 2 1 6 5 0 8 1 PCT~Pg5l0l4l4 growing medium, for sound or heat insulation and protection, for fire resistance and protection and as a filler or reinforcement.
The following are examples of suitable compositions, S (determined by X-ray flu~ analysis and measured as weight ~) and their di~solution rate at pH 7.5 in nm per day. ~ach composition can be melted in a cupola furnace and fiberised as in W092/06047.
Compositions 1, 2, 3 and 4 are within the invention while lA, lB, 2A, 3A and 4A are apparoximate comparisons and ~how that omitting the boron re~ es dissolution rate.
The comparative, borate free, compositions tend to slag formation, especially with the higher phosrhorous contents.

- Y~
-- I~
u~ CO ~ ~ r7 ~ ~
0 ~ d Ul d U~ N 15- ~1 C ~:

-- N ~ 0 N '.tl " ~ ~ ~ ~ N d ~' N

~ ~ N N O~
" ~ O O ` O ` O ` O
Q ~ ~ e~

o o o o o o o o o Q ,q ~ `d ~1 1 ~1 _I ~1 g5 d dq d O O O O

O ~I t` ~ N N
O O OO O q~

13 ` ` `` ` ` N
U ~ I 1'1 N N

1~ N ~ N C~

E-~ ~ d ul n 3 ~ I

~ ~ ~ N N

Claims (11)

11

1. Mineral wool formed of MMV fibres having a composition, expressed as oxides by weight of total composition, which is SiO2 35-66%
Al2O3 up to 10%
CaO 10-45%
MgO 2-30%
FeO up to 10%
Na2O + K2O 0-7%
TiO2 0-10%
P2O5 + B2O3 and other elements up to 20%
and which includes both P2O5 and B2O3.

2. A wool according to claim 1 in which Al2O3 is up to 4%
and each of P2O5 and B2O3 is up to 10%.

3. A wool according to claim 1 or claim 2 in which SiO2 is 53.5 to 65%, CaO is 10-30%, MgO is 5 to 20%, and FeO is up to 9%.

4. A wool according to claim 1 in which the composition includes SiO2 53.5-64% by weight Al2O3 up to 4% by weight CaO 10-20% by weight MgO 10-20% by weight FeO 6.5-9% by weight P2O5 + B2O3 up to 20% by weight and each is up to 10%.

5. A wool according to claim 1 in which the composition includes SiO2 53.5-65% by weight Al2O3 up to 4% by weight CaO 15-30% by weight MgO 5-15% by weight FeO up to 4% by weight P2O5 + B2O3 up to 20% by weight and each is up to 10%.

6. A wool according to claim 1 in which the composition includes P2O5 and B2O3 and SiO2 45 to 60%

Al2O3 0.5 to 4%
CaO 10 to 35%
MgO 5 to 15%
FeO 1 to 10%
Na2O 0 to 4%
K2O 0 to 2%
TiO2 0 to 2%
other elements 0 to 5%

7. A wool according to any preceding claim including P2O5 in an amount of 1 to 5% and B2O3 in an amount of 1 to 10%, preferably 1 to 5%.

8. A wool according to any preceding claim in which the amount of P2O5 is 0.5 to 4.5% and/or the amount of B2O3 is 0.5 to 4.5%.

9. A wool according to any preceding claim having a dissolution rate at pH 7.5 of at least 30nm/day.

10. A process of production of MMVF wool as defined in any preceding claim comprising providing raw materials to give the composition, providing a furnace, heating the raw materials in the furnace to a temperature between 1,400°C and 1,600°C to provide a melt fiberising the melt, and collecting the fibres as wool.

11. A process according to claim 9 in which the furnace is a cupola furnace.