NL8200604A - DRY MASS TO BE USED AS A FIBER MASS. - Google Patents

Description

ΙΡΡΙΙρΓ ^ 3 ....... 1 ....................

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Br / Bl / lh / 69

Dry mass to be used as fiber mass.

The invention relates to a dry mass for use in spraying masses for making refractory or flame-resistant coatings containing ceramic fibers, binders and other conventional additives.

5 It is known to use ceramic fibers in so-called fiber spray masses. For this purpose, ceramic fibers with large amounts of water are either first mixed and then sprayed on perpendicular walls or on ceilings using a spraying device for making a refractory or flame-resistant coating or injected into hollow spaces.

For example, DE-AS 26 18 813 fiber png masses are known which, in addition to a fairly large amount of inorganic fibers and small amounts of binder, respectively. other inorganic additives still contain an additional chemical binder, wherein these fiber spraying masses still contain 5-20% by weight of the oil to avoid dust formation.

In another method, dry ceramic fibers, on the one hand, and water, on the other hand, are supplied to the head of a sprayer, mixed together in the head of this sprayer, and then sprayed onto perpendicular walls on ceilings or sprayed into hollow spaces.

Furthermore, it was also already known to add further additives, such as binders and other conventional additives, to the above-described suspension of ceramic fibers in water.

However, because of the large amounts of water required in spraying, it is difficult to homogeneously mix these additives, such as binders and other conventional additives, with the fibers in the sprayer and to obtain a tightly adhering mass.

The object of the invention was now to provide a dry mass or dry mixture to be used as fiber injection masses, which resp. that can be applied on metal sheet walls as well as on walls up to a thickness of 30 cm. Furthermore, a mass had to be provided which can be heated at high temperatures immediately without separate drying.

As a solution to this problem, the above-described dry mass or the above-described dry mixture, as further described in the characterization of claim Ι- ΙΟ Preferred embodiments are further explained in claims 2-4. '

The ceramic fibers or mineral fibers present in the dry mixture according to the invention can be all conventional fibers of this type, for example rock-wool or fibers or aluminum silicate base with a particularly high A 2 O 3 content in the range of 45-95 wt% - It is of course also possible to use mixtures of different ceramic fibers.

In an advantageous embodiment of the dry masses according to the invention, the ceramic fibers are present as released fibers. For this purpose, commercially available fibers are supplied in the delivered state in a turbo-mixer (manufactured by Drais-Turbulent-Schnellmischer), in which the fibers usually supplied as fiber bundles are converted into exposed fibers. Such a turbo-mixer consists of a mixing unit with rapidly rotating blade heads, whereby any existing agglomerates, commercially available fibers, which are partly present in highly compacted form, are released without the fibers being crushed or crushed inadmissibly. .

The clay present in the dry mass according to the invention can be a conventional clay or a special binding clay, for example bentonite. This clay is usually used in an amount of 5-20 parts by weight per 100 parts by weight of the ceramic fibers, preferably 8-15 parts by weight of clay are used.

The components extra fine Al and / or extra fine S1O2 and / or aluminum hydroxide and / or extra fine magnesium oxide and / or extra fine titanium dioxide and / or extra fine, which may be present in the composition of the masses according to the invention. chromium oxide are components known in the art in the field of refractory materials.

The term "extra fine" as used herein with respect to the above constituents is understood to mean that these constituents are present in extremely finely ground or also in colloidal state. In particular when using such materials present in a colloidal state, such as a colloidal SiC grater. colloidal alumina, it is possible to use only small amounts of binder, namely near the lower limit of 1 part by weight of the organic binder and 2 parts by weight of a phosphate binder. The use of approximately equal amounts of phosphate binder and methyl cellulose as the organic binder is particularly preferred. It is also particularly advantageous to use a mixture of clay and one or more of the above-mentioned other additional 20 fine refractory components, the amount of these other additional fine refractory components usually being 1-3 parts by weight and the remainder being clay so that in total the amount of 2-20 parts by weight of refractory components stated in the claim is present. Furthermore, 0 to 10 parts by weight of chamotte flour are present in the dry masses according to the invention. This may be a random, finely ground chamotte, preferably the maximum grain size of the flour is <63 / ml and in particular <44 µm.

The dry mass according to the invention further contains 2-8 parts by weight and preferably 3-6 parts by weight of a phosphate binder, the indicated amounts in parts by weight refer to R 2 in the relevant binder.

Examples of such phosphate binders are sodium polyphosphate with a polymerization degree of n-4 and preferably with a polymerization degree of 6-10. This sodium polyphosphate is used in solid form. One further

V

8200604 • -4- Phosphate binder is monoaluminum phosphate which is a commercially available product in solid ground form.

A solid organic binder is present in the dry masses according to the invention. All organic binders commonly used in this field can be used for this purpose, for example, methyl cellulose, sulfitic caustic or molasses.

The preparation of the dry mass according to the invention takes place in such a way that the individual components are placed in a mixing device in any order. For this purpose, a conventional mixer or also a turbo mixer, as described above, can be used. Instead of using already decomposed fibers for the preparation of the dry mass according to the invention, also commercially available ceramic fibers can be introduced together with the other constituents in such a turbo-mixer and the decomposition of the ceramic fibers and intimate mixing thereof with the other ingredients are carried out.

The dry mixtures according to the invention can be sprayed with a conventional spraying machine, as is customary in concrete processing technology. Here, the water required for curing is supplied to the spray nozzle. Since the dry mass according to the invention is already in the form of an intimate mixture with the homogeneously distributed binders, the amount of water required for application is much smaller than with the hitherto known dry masses, which are also sprayed in this way .

The invention is further elucidated by means of the following examples.

In the examples, ceramic fibers A and B were used which had the following chemical composition: Fibers A) Al2 O3 = 47%; SiC> 2 = 53%; Fibers B) Al2O2 = 95%; SiO2 = 5%.

Example I

The following mixture was used; 8200604 '\ v * * · * - «* -5-

Wt. share

Ceramic fibers A 100

Binding clay (with 35% A ^ O-j) 10

Chamotte flour <63 µm * 10

Sodium polyphosphate, solid 6 5 Methyl cellulose, solid 2

These ingredients were mixed thoroughly in an Eirich mixer for 20 minutes.

The dry mixture was sprayed with a spraying machine / supplied to the nozzle with compressed air and mixed therein with water also supplied.

With this dry mass, thicknesses of 30 cm sprayed on perpendicular sheet metal walls could be formed. The mass introduced by spraying could be heated immediately without separate drying. Such a spray applied mass exhibited the following properties:

TABLE A

Condition Fresh through

spray 300 ° 1000 ° C 1200 ° C

_ applied 8. h 12 h_24 h_ ^ Fill weight (g / cm ^) 0.86 0.57 0.56 0.65

Cold flexural strength, KBS (N / mm2) n.a. 0.5 0.6 1.3

Cold compressive strength, KDS (N / mm2) n.a. 0.5 1.0 2.3 25 Thermal conductivity (W / m ° K) at 400 ° C 0.15 at 600 ° C 0.18 at 1000 ° C 0.20 at 1100 ° C 0.21 NA = not measurable.

Example II

The following mixture was used:

Parts by weight

Ceramic fibers B 75

Ceramic fibers A 25 35 Binding clay, with 35% A ^ O ^ 10

Mono-aluminum phosphate, solid 6

Sodium polyphosphate, solid 2 NMethylcellulose 3 8200804 -6-

First, the ceramic fibers were converted into digested fibers in a turbo mixer over 15 minutes.

Then the other ingredients were added and 5 was mixed in the turbo mixer for an additional 3 minutes.

After processing according to the method of Example I, the following properties were determined on the dry mass processed as fodder spray mass:

TABLE 'B

10 Condition Fresh through

spray 300 ° C 1000 ° C 14Q0 ° C

applied .8 h .1.2 h 24 h

Fill weight (g / cm3) 0.6 0.4 0.4 0.5 KBS (N / mm3) n.a. 0.4 Q # 4 0.7 KDS (N / mm) n.a. 0.5 0.7 2.0 * \ 8200604 k. ·

Claims (4)

Dry mass for use in spraying masses for making refractory or flame-resistant coatings # containing ceramic fibers # binders and other conventional additives, characterized in that they contain 5 a) 100 parts by weight of ceramic fibers, b) 2 to 20 parts by weight parts of clay and / or extra fine Al and / or extra fine SiC> 2 and / or aluminum oxide and / or extra fine magnesium oxide and / or extra fine titanium dioxide and / or extra fine chromium oxide, 10-10 wt. parts of chamotte flour, d) 2-8 parts by weight of a phosphate binder, calculated as P2 ° 5 'and e) 1-4 parts by weight of a solid organic binder, these components being intimately mixed. Dry mass according to claim 1, characterized in that it contains ceramic fibers disclosed as ceramic fibers. Dry mass according to claim 1, characterized in that it contains bentonite as clay. Dry mass according to claim 1, characterized in that it contains sodium polyphosphate or monoaluminum phosphate as the phosphate binder. V <, 82 0 0 6 04