DE2804069A1 - Non-flammable sheet or felt of mineral fibre - impregnated with alkali silicate and dried without dust formation - Google Patents

Abstract

Non-flammable sheet or felt of alkali silicate bonded and/or coated mineral fibre prods. are prepared using as the mineral fibres glass fibres contg. oxides of transition metals, in a process including rapid drying of the bonded mineral fibre body without druing the excess. The drying technique avoids prodn. of crystalline alkali silicate thus avoiding deterioration of the bonding, with consequent dusting.

Description

It is known in the manufacture of bEneral fiber products such as

Sheets or sheets, the binding of the mineral fibers by means of plastic to replace it with one by means of a glass of water, thereby making it cheap non-flammable mineral fiber products. The products made in this way however do not meet the requirements to be made of them, because those with water glass Impregnated mineral fibers are so badly affected by the water glass that they embrittle or even disintegrate when drying.

To this on the alkaline reaction of the water glass with the glass fibers To eliminate the phenomena that can be attributed to, for example, according to US-PS 3 00 / 857 already switched to the pH value of the water glass, that of water glasses corresponding concentration is 11-12, through the addition of acidic boron compounds lower to at least 10.

The use of calcium sulfite for this purpose is also already included to the state of the art, as can be seen from DE-AS 23 28 056.

According to BE-PS 829 527 the water glass to achieve the same Substances that split off acetic acid were added to the result in the heat.

After all, according to W. Russewa and W. Simowa "products from Mineral wool with inorganic binders "Building materials industry 18 (1975) Volume 5, Page 25 also already contains potassium or magnesium chloride or aluminum sulphate same goal used in the production of mineral trxlleplatte.

The reduction in pH achieved by the known methods leads to the fact that the attack of the water glass on the mineral fibers is limited or even avoided, but when using such binders, more or less silica is released, which leads to embrittlement of the binder and thus leads to a reduction in its adhesive strength.

According to DE-ASs 14 46 999 and 14 71 011 can be thermally insulating Flange protection layers without measures to lower the pH value as a binding agent Manufacture used water glass. In the manufacturing process described there thermally insulating flame retardant layers from alkali silicates With embedded glass fibers, metal grids or the like, drying is carried out at temperatures below 1000C overnight or

for a total of 2 1/4 hours and therefore an early one Prevents foaming of the waterglass matrix. Even if the Mineral fibers should not be attacked by the binder used, is the mineral fiber boards bonded on the basis of water glass for drying required drying time not economically viable.

According to DE-OS 21, for example, it belongs to the state of the art 23 393 also, in the production of mineral fiber boards from slag or.

Mineral wool with a binding agent made from magnesium oxide or hydroxide and solid silicates, in particular alkali metal silicates to work, with subsequently curing under pressure at 150 to 1800C is carried out. This procedure too However, it is not satisfactory because the use of solid alkali silicates means that it is more discrete Particles, although the attack can be localized and therefore less noticeable, however it definitely exists. Add that water glass in solid form not available with a fineness corresponding to the fiber diameter and scmit no binding in the smallest areas is possible.

The object of the invention is to provide a method for the production of not to propose combustible bUneral fiber products with economically short drying times and using liquid alkali silicate-based binders to non-brittle, bound and / or coated mineral fiber products.

According to the invention, this object is achieved by the use of Oxides of the glass fibers containing transition metals as a mineral fiber component rapid drying of what has been provided with the binding agent to prevent overdrying Mineral fiber component.

Developments of the method according to the invention are in the subclaims marked.

For the successful implementation of the procedure for the creation of non-flammable mineral fiber products according to the invention are therefore necessary measures which mutually act on one another in such a way that the one on which the invention is based Task becomes solvable.

One measure is to use a special type of mineral fiber product to be selected as the starting material, namely those that are at least partially resistant to alkalis are.

So you have to choose mineral fibers that are not just made of glass fibers consist of only oxides of the main group elements of the periodic table, like SiO2, A1203, B203, Na2O, K20, CaO, MgO, BaO and small amounts of unwanted ones Contain impurities. These fibers form because of their low alkali resistance a particularly unfavorable starting product. One is therefore, proposing the Following the invention, choose fibers that are in addition to some or all of the foregoing Oxides also contain those of the transition metals, such as TiO2, Je203, Cr203.

The oxides of the transition metals used according to the invention Glass fibers are already known per se in connection with the reinforcement of cement products Because of their improved alkalinity it is sufficient in this field of application Experience has shown that the improved alkali resistance is not fully effective and it kants in the Over a long period of time, the glass fibers will decompose. For the purpose of In accordance with the invention, however, this improvement in alkali resistance is surprisingly sufficient because, in connection with the special type of drying selected, embrittlement of the binder is avoided, so that an attack that has actually taken place the same on the glass fibers because of the intimate bond of glass fibers and binder has no effect.

As a particularly inexpensive mineral fiber containing iron oxide is here Basalt wool called, which is used especially there without difficulty can where their dark color does not interfere.

To achieve the object underlying the invention can as Sodium silicate binder can be used. You get better results However with potassium silicate. In any case, however, care must be taken to ensure that the Big properties of the alkali silicate binders not to endanger again to obtain the otherwise required properties, such as good curing, water resistance, Temperature resistance etc.

only those additives are used that the binder does not become brittle. Acid substances are thus because of the release of silica from the Alkali silicates not suitable. Instead, one expediently uses oxides, hydroxides or alkaline earth, zinc or aluminum silicates. The additives are Only allowed in limited quantities and their fineness should be as great as possible.

Finally, the other combination feature is drying required under mild conditions. This is supposed to be a forceps action the hot binder solution on the fibers can be avoided, i.e. drying must go quickly. On the other hand, overdrying should also be avoided , i.e. a certain, chemically bound residual water content should remain, although the binder is already completely dry. The term "overdrying" can therefore best be defined as the beginning of overdrying at that point in time in which the chemically bound water also begins to evaporate.

Examples are blowing heated gases through the Impregnated mineral fiber material or microwave drying mentioned.

That it is the result of the process according to the invention for the use of measures, it is not simply an addition of the effect These measures are to be explained in more detail below.

A comparison material is a glass wool with the following composition of the glass material called: 63% by weight SiO2 3% by weight A1203 6% by weight B2O3 14% by weight Na2O 0.8% by weight K2O 7.4% by weight CaO 3% by weight MgO 2.5% by weight BaO 0.3 % By weight Fe2O3 as difficult to avoid, but also not for reasons of melting technology undesirable-100.0% by weight of the impurity This is compared with the behavior of a Glass wool of the following composition: 61.5% by weight SiO2 2.9% by weight Al2O3 5.9% by weight B203 13.7% by weight Na2O 0.8% by weight K2O 7.2% by weight CaO 2.9% by weight MgO 2.4% by weight BaO 0.3% by weight Fe 2 O 3 as difficult to avoid, but not for reasons of melting technology undesired impurity 2.4% by weight Cr203 as a desired additional glass component.

100.0% by weight are compared with each other as binders: normal Water glass with a molar ratio of SiO2: Na2O = 3.35 to ap% by weight (SiO2 + Na2O) diluted.

and Xali water glass with a molar ratio of Si02 : K20 = 3.35 diluted to (weight) 10% (SiO2 + K20), as well as drying types: drying in the drying cabinet drying in the microwave cabinet 7 g of the wool in question - in Form a round, unbound mat -were on a porcelain nutsche with the Poured over specified diluted water glass. The excess was filtered off with suction. the wet mat weighing 17 to 18 g was then roughly equally thin in six Split fleece to prevent the waterglass from migrating when drying in the drying cabinet to prevent, as well as to improve the starting conditions for the subsequent vibration festival to have.

Depending on the drying method chosen, the aforementioned nonwovens were then either in a drying cabinet at 120 ° C. or in a commercially available microwave cabinet dried, which has a drying time of about 50 to 60 minutes and 5 to 6 minutes, respectively required. The resulting bonded nonwovens with a binder content of 14 to 16%, based on the dry wool, was then used to determine its brittleness subjected to a vibration test. This vibration test is a kind of of sieve analysis using two standardized rubber cubes as so-called Sieve aids. 3 g; ADllevlies and two rubber cubes were placed on a sieve from 1 mm clear mesh size of a commercially available sieve machine and 5 minutes shaken.

Here, the rubber cubes trample onto the material to be tested and smash it more or less, depending on its brittleness. The resulting Fines fall through the sieve and are weighed and at the end of the test converted into% of the fleece weight used, which is a measure of the brittleness of the fleece.

The following results are shown Type of wool Binder Type of drying Dust content Glass wool dil., Norm. Water glass drying cabinet 120 ° 47% practically free "" microwave oven 24% v.üb. -Oxide "Potash" drying cabinet 42% 1200 42% 1 .. @ 1 microwave cabinet 18% Glass wool dil., Norm. Water glass drying cabinet 28% with Cr2O3 120 ° "Microwave cabinet 7% "Potash" drying cabinet 25% 120 ° """Microwave cabinet 3% This table clearly shows both the effectiveness of each individual measure and of all measures taken together.

When using a glass wool with Cr203 there is a reduction the brittleness, which roughly corresponds to that which is found at the point of drying normal glass wool in the drying cabinet to that in the microwave cabinet and which is around 50%. Assuming the drying process for a glass wool with Cr203 in the drying cupboard to one in the microwave cupboard, you get a surprising result a 75% reduction in brittleness.

If you go from this to glass wool bound with normal water glass those that are bound with potassium water glass, it is shown that this once again a disproportionate reduction in brittleness can be achieved.

In the following, some practical exemplary embodiments will be given will: Example 1 Wanted Used: Baalt wool of the following Composition: 46.3% by weight SiO2 13.5% by weight Al203 7.2% by weight Fe203 4.9% by weight FeO 2.9% by weight Ti02 10.9% by weight CaO 9.5% by weight MgO 2.7% by weight Na2O 1.1% by weight * K20 Best secondary components such as Nn0, P205 100% by weight Binder used: 860 parts by weight Potash water glass (molar ratio 3.35) 35% by weight (SiO2 + K2O) 4070 parts by weight of water 190 parts by weight kaolin, 95% <10μ 50 parts by weight zinc oxide, 95% <8 A 95 g of the present as a loose mat and cut to a format of 20 cm x 20 cm Wool, were doused with the binder solution, the excess with the help of a Fan sucked off, the wet mat pressed to a thickness of 15 mm and then dried in a microwave oven for 7 minutes. That way it was a dark plate with a binder content of 13% and a bulk density of 115 g / l obtained, which is completely unusual for a nineral fiber board bound with water glass - no longer showed any dust, i.e. fiber disintegration, during handling.

Example 2 Wool used: Glass wool containing chromium oxide, as in Comparison indicated. Binder used as in Example 1, but additionally with 5 g each of iron oxide yellow and chromium oxide green.

In the manner described above, a lime green plate was obtained, which also showed no dustiness.

Claims (8)

Process for the production of non-combustible mineral fiber products Claims 1. Process for the production of non-combustible, with alkali silicate Mineral fiber products bound as a binder and / or coated with alkali silicate, especially in plate or felt form, g e k e n n n -z e i c h n e t through the use of glass fibers containing oxides of transition metals as a mineral fiber component and by rapid drying of the with the binding agent to avoid overdrying provided mineral fiber component. 2. The method according to claim 1, characterized in that g e k e n n z e i c h n e t that the alkali silicate binder is oxides, hydroxides or silicates of the alkaline earths, of the zinc or aluminum are added in the finest possible form. 3. The method according to claim 1 or 2, characterized in that g e k e n n z e i c h n e t that heated gases to dry are blown through the soaked mineral fiber body will. 4. The method according to claim 1, characterized g e k e n n z e i c h n e t that the soaked mineral fiber body is dried by microwave ovens. 5. The method according to one or more of the preceding claims, by noting that the mineral fiber component is hot Binder solution is soaked. 6. The method according to one or more of the preceding claims, in that it is only used as a mineral fiber component SiO2, M2031 B203, Na2O, K20, CaO, MgO, Bao and small amounts of unwanted impurities containing glass fibers with an addition of TiO2, Fe203 and / or Cr203 are used will. 7. The method according to claim 6, characterized in that g e k e n n z e i c h n e t that the mineral fiber component Ba saltwol le is used. 8. The method according to one or more of the preceding claims, as a result, that as a binding and / or coating agent Potassium silicate solution is used.