WO2012048860A1

WO2012048860A1 - Intumescent heat-insulating fire-proof moulded part

Info

Publication number: WO2012048860A1
Application number: PCT/EP2011/005102
Authority: WO
Inventors: Rainer Angenendt; Peer Genth
Original assignee: TDH - GmbH Technischer Dämmstoffhandel
Priority date: 2010-10-13
Filing date: 2011-10-12
Publication date: 2012-04-19
Also published as: DE102010048174B4; DE102010048174A1

Abstract

The invention relates to an intumescent heat-insulating fire-proof moulded part for fire protection, with a heat value according to DIN EN 1716 of 3 MJ/kg or less. Said moulded part is characterised in that it contains at least one lightweight filler, exfoliated graphite, an inorganic-organic hybrid binding agent, and at least one mineral, and in that it contains fibres and/or mineral needles.

Description

Intumescent heat-insulating refractory molding

The invention relates to a molded part according to the preamble of claim 1. The term lightweight fillers are here to be understood as meaning high-melting mineral, in particular closed-cell, hollow spheres and granules of low density, for example glass hollow spheres, expanded volcanic ash, expanded perlite, etc.

The term molded part is to be understood here in particular as products with closed-cell hollow spheres and granules of low density, as described by the company.

VatramaXX GmbH, Hoogeweg 65, 47623 Kevelaer, for example VATRAL NA 125/150 KP or Vatral NA 125/150 M as a raw material for producing such molded parts. These moldings and the compositions for their preparation are described in detail in German Patent Applications Nos. 10 2010 009 142.1-45, 10 2010 009 144.8-45, 10 2010 009 146.4-45, 10 2010 009 148.0-45 and 10 2010 044 466.9 described.

The content of these patent applications will supplement the disclosure

expressly included in the present description.

State of the art

1. Despite decades of industrial experience and research, many flame retardant additives are either not sufficiently effective or toxicologically questionable. Therefore, the range of functional fire protection materials is still low.

Known are fire protection boards, which are marketed under the trade name "Knauf THERM AX" and contain expanded vermiculite, a three-layer silicate, as well as purely inorganic binders, but no fibers

(Density) of about 475 to 850 kg / m ³ .

Also known are purely inorganic fire-resistant glass fiber lightweight concrete, which are sold under the trade name "AESTUVER T" and have a density (density) of about 690 to 980 kg / m ³ .

2. Also known are fire protection coatings that foam independently in the event of fire and protect the object to be protected from the heat of the fire. In fire protection, the term intumescence designates the appropriate one

"Swelling" or foaming of materials. Intumescent building materials increase in volume under heat and decrease in density.

As a rule, intumescent substances are used in preventative structural fire protection, where they have the following tasks to tackle:

Are z. B. steel beams heated, so they lose from about 500 ° C their stability and load capacity. Buildings with structural elements made of steel girders would consequently collapse. Non-insulated steel beams reach this temperature in the event of a fire after only 5 to 10 minutes. On the other hand, steel beams with a fire protection coating can withstand a fire significantly longer. Also for wood and others

Materials there are appropriate fire protection coatings.

Fire protection coatings are usually applied by airless method or with a brush in several layers. The layer thickness is usually in the mm range. If the temperature exceeds a certain value, chemical reactions take place in the fire protection coating, causing them to foam (intumescence). The disadvantage here is the high concentration of toxic gases. These fire protection coatings are called Dämmschichtbildner. Of the

Foaming process usually starts at around 100 ° C. A layer with a thickness of 1 mm can foam in the event of a fire to approx. 50 mm and thus forms an effective heat insulation. The foamed layer consists of microporous "carbon foam." This layer decomposes over time in the course of the fire, which reduces the insulating effect.Some fire protection coatings insulate over one hour in case of fire.

It is also known that expanded graphite is introduced directly into plastics, for example in the insulation of cables. From the expandable graphite gases are released when exposed to heat, which together with the incinerating insulation material to form a "foamed" ash layer, which obstructs the supply of oxygen - and thus the flame propagation. The formation of toxic gases and smoke is significantly reduced. However, the toxic load is still high, and the poor fire class of the products and the associated prohibitions on use limit the

Applications.

3. Known is a thermally expandable fire protection compound (DE 41 35 678 AI). This material was designed exclusively for the case of fire and has no other useful properties such as low thermal conductivity or non-combustibility. A low thermal conductivity is achieved only after inflation in case of fire. Therefore, this material is not designed for a large-scale use as an insulating material and / or fire protection board as the invention. It is rather, as it is also described, in areas of pipe and

Cable penetrations and used for decay of joints. Another essential difference to the invention is the composition and the resulting calorific value. The formulations described on pages 5 and 6 all have an organic content of 50-99%, with expandable graphite being assigned here to the organic constituents because of its high calorific value. The calorific values of these formulations are between about 15 and 35 MJ / kg, which is much higher than in the invention.

The content of light fillers (here exclusively micro glass bubbles from 0.05 to 0.2 mm in size or plastic hollow spheres) is between 0.5 and 2%, ie much lower than in the invention, where the content of light fillers between 15 and 35% in the plastic mass lies.

The function of the mass according to DE 41 35 678 AI is based on the structure of a

Carbon skeleton. By contrast, according to the invention, a mineral scaffold is built up, if at all, with the appropriate back pressure.

The according to DE 41 35 678 AI binders, especially phenol-formaldehyde resins and chloroprene rubber, etc. set extremely many and also toxic fumes free, which led to the partial prohibition of these materials in ship and rail vehicle. In building construction these materials are prohibited in escape routes and rooms with special fire protection requirements due to the bad fire class and the release of toxic flue gases. The materials of the invention would all of these Requirements exist.

4. In US 5,736,109 the preparation of a catalyst or diesel particulate filter with a housing, a catalytic converter element or diesel particulate filter element and an intumescent plate material between the

Catalyst element and the housing described. Used here is vermiculite, which is already bloated for the most part. Vermiculite only puffs at approx. 850 ° C and is therefore not suitable as a potting material in fire protection.

Background to the structural fire protection

The structural measures, for example in buildings, are very diverse and extend from the building materials and components used, regulated in Germany in DIN 4102 and ENV 1992-1-2, on the structural fire protection in industrial buildings, regulated in the DIN 18230, on the Escape route planning towards extinguishing systems in buildings. In Austria, this is specified in the various TRVB-B.

In Germany, it is necessary to have a fire safety report prepared by an approved fire protection expert for every major construction. In addition, the created fire protection concept must be coordinated with the local authorities. A federal law delegates the responsibility to the state responsibility. The regulations therefore differ from state to state. In Austria, fire inspections are subject to fire prevention agencies (also within the sovereignty of individual federal states). In Switzerland, it is regulated by cantons.

Structural measures must take into account the following aspects in particular:

• Fire behavior of building materials

Fire resistance of the components

Division of buildings into fire zones through fire walls and

Fire doors

escape route planning

active fire fighting by sprinkler systems Especially the ever-increasing penetration of large buildings

Power supply, control and data lines runs the required by the construction supervision section separation with firewalls and fire resistant

Floor ceilings contrary. Therefore, in modern buildings with larger crowds of people (eg train stations, airports, museums,

Congress halls) special fire protection equipment such as fire alarm systems,

Emergency lighting, fire doors and fire doors as long as possible

maintained. In public buildings in Germany, the use of halogen-free cables (not PVC) is standard. Power lines that run through several fire compartments must be secured with a firewall. Electrical cables that are used for mechanical smoke extraction or a fire alarm system must have a fire resistance duration (with functional integrity) of E90 or E3 O, depending on the application.

Not to forget buildings that are restricted in their movement

People are used or inhabited (hospitals, clinics, homes for the elderly, senior citizen housing, etc.).

Structural fire protection has become increasingly important for tunnel structures in recent years due to the dramatic tunnel fires. In addition to the

Complying with constructive rules makes computational proof (the so-called "hot dimensioning") increasingly important, and regulations for computational proof can be found, for example, in ENV 1992-1-2, ZTV-Ing and the "Guideline for the Fire and Civil Protection "of Deutsche Bahn.

Task and solution of the invention

The invention has for its object to provide extremely light, stable and sufficiently flexible fire protection moldings with high strength at fire action of the type mentioned, which are intumescent, a density of less than 0.5 g / cm ³ (corresponding to 500 kg / m ³ ) and, when executed as a laminate, a

Melting point according to DIN 4102 have greater than 1000 ° C without intumescent completely and thus to ensure the required fire.

This object is achieved by the features of claim 1. With the natural graphite-based expandable graphite an effective and environmentally friendly flame retardant additive is available, which has already been successfully established in a number of applications.

The natural mineral graphite has a pronounced lattice structure. For the production of expanded graphite in these layers sulfuric or

Embedded nitrogen compounds. When exposed to heat, the graphite layers are suddenly driven apart. As a result, the graphite particles expand to several hundred times their original volume.

The expandable graphite can be easily incorporated into existing aqueous systems or mortars. In case of fire, the expandable graphite expands by heat to several hundred times the original volume and forms a

Intumescent layer on the material surface. This stops or slows down the expansion of the fire and counteracts the most dangerous consequences for humans, the spread of toxic gases and smoke.

Technical data of standard expanded graphite

^• Expansion rate 120 to 350 cmVg

^■ Average expansion temperature 160 to 300 ° C

^• Carbon content: 85% to 99%

^• calorific value approx. 32 MJ / kg

· Particle size: 50 to 300 μπι

In addition to low-cost standard qualities, products tailored to special applications are offered. For example, there are pH-stabilized expandable graphites used in mortars or products with special particle size requirements.

The term hybrid binder is understood here to mean a binder with both inorganic and organic fractions. Detailed explanations can be found below after the subheading "hybrid binder used according to the invention". Preferably, the hybrid binder used contains fine particles, which in turn are composed of amorphous silica particles containing as binders an acrylate-based polymer, in particular n-butyl acrylate and

Methyl methacrylate and / or latex.

Further advantageous embodiments of the invention are set forth in the subclaims.

According to the invention, the combination of hybrid binder and

dehydrating mineral. The hybrid binder allows for a

correspondingly high proportion the high strength and flexibility of the

Fire protection molding with a low weight and calorific value. The flammability of the organic fraction of the hybrid binder is additionally suppressed by the dehydrating mineral, which releases water at elevated temperature and thus acts quasi as an extinguishing agent.

The combination of hybrid binder and dehydrating mineral can thus surprisingly extremely low density while still good

Fire resistance can be achieved. In particular, the dehydrating mineral prevents the ignition of the flue gases in case of fire.

Preferably, the amount of the organic and its calorific value of the density and the proportion of inorganic material is adjusted. However, dehydrating minerals are only adjusted to the proportion of combustible organic gases occurring in the event of fire, so that the consideration of the calorific value / combustible gases in the

Recipes can meet the requirements of the required fire protection class. Example see Recipes.

Classification of the European fire class is in accordance with DIN EN 13501-1, Classification of construction products and types of fire behavior - Part 1:

Classification with the results of the fire performance tests of construction products, based on the following test standards and classifications.

The fire behavior of a building material is classified according to the following scheme:

EN

Test method

class Non-combustible building materials

DIN EN ISO 1 182, DIN EN ISO 1716, without fractions of flammable

DIN EN 13823

building materials

Non-combustible building materials

DIN EN ISO 1182, DIN EN ISO 1716, with fractions of flammable

DIN EN 13823

building materials

Flame-retardant building materials B DIN EN 13823

Flame-retardant building materials C DIN EN 13823

Normally flammable building materials D DIN EN 13823

Normally flammable building materials E DIN EN ISO 1 1925-2

Highly flammable building materials F No examination

According to the European standardization finer subdivisions of the

Fire classes made according to their fire behavior. There, among other things, the measure of the smoke development and the burning dripping into the classification is included.

Up to the fire class B / C the building materials are regarded as self-extinguishing. From

Fire class D the fire maintains itself, even if the cause of the fire is eliminated.

Therefore, only the fire classes A - B are relevant for the invention described here.

A test in accordance with DIN EN ISO 1 182, Tests on the fire behavior of

Construction products - Non-combustibility test, can not be performed on intumescent building materials due to the test arrangement. Tests according to DIN EN 13823, Tests on the fire behavior of construction products - Thermal stress from a single burning object for

Construction products, with the exception of floor coverings, are not critical for the products of the type described in the introduction, since the expanded graphite used does not participate in the firing process in this test. For the achievement of the European fire class B this examination is sufficient.

In order to achieve the European fire class A, additional tests in accordance with DIN EN ISO 1716, Tests on the fire behavior of construction products - Determination of heat of combustion must be carried out. For reaching the European Fire Class AI shall not exceed 2MJ / kg of combustion heat and for the

European fire class A2 does not exceed 3MJ / kg. This will be in the

products according to the invention by adjusting the density, the

Intumescence factor (expanded graphite / 1) and heat of combustion (organic / kg) reached. If the density of the product is increased by the addition of non-combustible fractions, the reduction of the heat of combustion / kg can increase the proportion of expandable graphite / 1 and thus the intumescent factor. In this way, it is possible to produce specifically intumescent products of the respective European fire class. Example: In the range of gross densities of 100 - 500 kg / m ³ , the calorific value in the VATRAL products without expanded graphite can be reduced from approx. 1 to 0.2 MJ / kg. Depending on the density, it is therefore possible to add more expandable graphite per volume, which increases the expansion factor. See Figure 1, which shows the expansion of non-combustible VATRAL products, namely the expansion factor as a function of the apparent density in kg / m ³ . The upper curve shows a product with 3 MJ / kg, the lower curve a product with 2 MJ / kg.

Particularly noteworthy is the combination of different formulations with different levels of expandable graphite. Due to layered structure of the moldings can be without additional measures, despite the otherwise contradictory

Properties such as intumescence and stability, which ensure fire completion. Since VATRAL products can also be added locally with expandable graphite, constructive cavities required can be closed in the event of a fire.

The geometry of the molded parts is basically no limit. Even molded parts with complex geometry can be produced. Stones, pipes, hollow bodies and other shaped parts can be produced as well as mainly plates. The density of 0.1 to 0.5 g / cm ³ is well below the gross densities of known smoke-tight

Fire protection boards (mineral fiber boards always require a stable, dense surface layer for smoke-proofing and ensuring fire protection). The achievable thermal conductivity of about 0.04 W / mK at 10 ° C is much better, namely significantly lower than in known fire protection boards. For the preparation is based on an aqueous mass, which are prepared by known molding methods, subsequent drying and thermal treatment treatment to about 1 10 ° C. For example, the following molding methods are suitable:

· Vibration presses with low load,

Isostatic pressing,

Manual or mechanical stamping or ramming for complex shapes or smaller number of parts to be manufactured,

• extrusion or extrusion process,

· Slip casting, in particular for special parts, but also for larger blocks, wherein the water content of the masses prepared for slip casting is about 5 to 15% higher and contains thickening agents

• Rollers. Before drying, a careful and as complete as possible tempering to the drying temperature is recommended in order to avoid drying cracks or errors during drying. Drying can be carried out at room temperature or at temperatures of up to 70 ° C. A short-term drying at about 1 10 ° C decomposes the wetting agent specially used for this case and increases the

Hydrophobicity.

In the event of fire, the organic components of the hybrid binders are thermally decomposed above 160-400 ° C and intumescent with the expanded graphite areas and disintegrate into a very light powdery mixture

Expanded graphite, minerals and light fillers. The binders embrittle, but maintain their binding effect by the inorganic content, which on the one hand increases the floc size in the pressed with expandable graphite part and on the other hand, the stability against fire in stratified products. At the same time, the dehydration of the mineral fillers prevents ignition (burning off) of the flue gases occurring at short notice.

Properties and production of the plastic mass used as starting material for the production of the heat and sound insulating intumescent according to the invention

Fire protection products serve

The light filler used is expanded cellular volcanic rock in the form of non-porous hollow granules and / or glass hollow spheres. For porous hollow granules would on the other hand increase the bulk density, more glue (= higher calorific value) and more minerals would be required, the masses would be dull and would be worse to process and the porosity of the final product would increase significantly.

Binders used are hybrid binders whose basic structure

is primarily inorganic. This results in a reduction of the calorific value, and the bond remains, albeit with different properties, at high temperatures. Since these binders hardly shrink when burned, the layered fire protection moldings change their dimensions under fire load in the area with low or no share of expandable graphite only insignificantly.

According to the invention, the mass after hardening is extremely stable, layered

Moldings show virtually no shrinkage, no external cracks and no crumbling even with a one-sided temperature stress of 1000 ° C outside. The

Application temperature is, however, only at 150 ° C due to the contained expandable graphite and the hybrid binder and the dehydrating minerals. The innovation of the product according to the invention consists in particular in that, in addition to suitable hybrid binder systems and coordinated dehydrating minerals, which sufficiently crosslink the support structures of fibers and mineral fillers already during drying under room temperature with the lightweight fillers (expanded volcanic rock and / or glass hollow spheres) and due their organic content gives the moldings the necessary strength, vibration stability and flexibility for further processing and application, quantities of expanded graphite matched to the European fire classes AB can be used homogeneously or locally. The inorganic portion of the hybrid binder also maintains binding above the combustion of the organic portion.

It is particularly innovative that the inorganic residues of the hybrid binder and the dehydrating mineral granules and fillers in the event of a fire adjusting temperature increase so complement each other that they are stratified

Moldings in the areas with reduced expanded graphite contents have a strengthening effect and thus a remnant of dimensionally stable fire protection board is retained. A key customer benefit when using the products according to the invention lies in more efficient light and narrow fire protection structures. Especially in the field of shipbuilding, but also in fire protection for trains, etc., are weight and

Space savings always required.

Further important advantages of the products according to the invention:

• Fire Classes A and B

• Low weight

• Low thermal conductivity

• Good strength properties

· Easy installation and processing

• Many combination options

• Low flue gas development

• No odor development

• Non-hygroscopic

· Hydrophobic

• Water-conducting (lotus effect)

• Chemical resistant

• Good electrical insulation

• Landfillable

Light fillers used according to the invention

Perlite (English: perlite) refers to an altered (chemically and physically transformed) volcanic glass (obsidian) in the geosciences and thus belongs to the rocks. The so-called pearlitic structure here is about pea-sized

Glass beads formed. Perlite contains up to 2% water and has a density of about 900 to 1000 kg / m ³ (bulk density of the crude perlite). By annealing at about 800 ° C to 1000 ° C perlite inflates to fifteen to twenty times its

Volume and then has a bulk density of 50 to 100 kg / m ³ and a thermal conductivity of λ = 0.040 to 0.070 W / mK.

According to the invention, these perlites can not be used because of the porosity.

In contrast, microcellularly expanded volcanic rocks, cenospheres and glass hollow spheres are suitable according to the invention. Microcellular expanded volcanic rocks are made using new environmentally friendly and energy-saving processes, achieving the properties and technical values of older, porous expanded volcanic rocks ("expanded perlites"). Microcellular expanded volcanic rock is a filler from the group of aluminum silicates and is composed of spherical ("honeycomb"), rod-shaped and flaked particles, resulting in high packing densities and higher bond strengths than conventional hollow microspheres due to mechanical and cohesive bonding forces.

Targeted surface coatings enable an advantageous bond with the inorganic or organic matrix. This results in less shrinkage and better technical properties. Commercially available is blown impregnated perlite z. B. under the trade name NOBLITE® (product of the company NOBLITE, Route de Claye, F-77181 LE ΡΓΝ, France) and Technoperl® (product of Europerl Germany, D-94032 Passau, Nibelungenplatz 4).

In order to achieve particularly low densities, the combination or the sole use of hollow glass microspheres, as z. B. 3M offers proven.

Optionally used fibers according to the invention

In particular, inorganic fibers, for example ceramic and / or mineral fibers and / or mineral needles, are used.

Hybrid binder used according to the invention

Preferably, an organic-inorganic hybrid binder is used which is available under the trade name Levasil 4063 from Obermeier, and / or COL. 9 of the company BASF. Both products contain amorphous silica particles and

Polymers based on latex or n-butyl acrylate and methyl methacrylate (see FIG. 1). The particles are dispersed in water. The stickiness of the particles due to the polymer content gives an excellent binder for low temperatures, up to about 180 ° C. At elevated temperatures, the decomposes

Part of the polymer and the silica particles remain and thus preserve the structure, the silica particles also forming a solid framework at a correspondingly high temperature. Shrinkage therefore does not occur at either low or elevated temperature. The binders have a solids content of about 35 to 60 wt .-%. The silicate content, based on the solids content, is 75 to 95% by weight or 30 to 50% by weight. Dehydrating mineral fillers used according to the invention

Preferably, surface-treated aluminum trihydrate is used, e.g. B. Trefil 744-300 EST and / or Trefil 744-300 MST the company Quarzwerke GmbH.

In addition, a surface-treated silica is used. Silica is an intimate mixture of finely divided silica and kaolinite. For example, the Neuburg Siliceous Earth is known, which is preferably used according to the invention. For better wettability with water, the silica is treated with a silane so that the individual particles have a functional hydrophilic surface.

Such an activated silica is available under the trade name "AKTISIL EM" from Hoffmann Mineral GmbH, Neuburg (Danube) Here, the silica is treated with 3-epoxypropyloxipropyltrimethoxysilane.This so-called activated silica can be used in powder form the use of a mixture of silica sol and kaolin / kaolinite.

Production examples and example formulations

All liquid components of the formula are accurately weighed and carefully mixed to avoid foaming. Here simple anchor or Zahnscheibenrührer have proven in practice.

The precisely weighed fibers are evenly added in small units to this mixture, by stirring (at low speed) completely wetted with the aqueous solution (avoid knot formation).

After that, the precisely weighed lightweight fillers, expandable graphite and the

Minerals mixed with each other in a free fall mixer and fed to a compulsory mixer (eg company BEBA). Both premixes are mixed together with uniform slow stirring for about 25 minutes. High shear forces, pressure and friction are to be avoided as far as possible to avoid the microcellular

Not to damage volcanic rocks.

The light fillers should be completely wetted to give a uniform loose mortar or mass. Recipe for 100 kg plastic mass (fire class A2) for molded parts with a bulk density of approx. 250 kg / m ³ and an expansion factor of approx. 6 water 41, 5 kg

Mineral wool (eg loose wool from Rockwool) 3.5 kg

Hybrid binders (COL 9 from BASF / Levasil 4063 from Obermeier)

13.0 kg

Glass hollow spheres (Kl 5 from 3M) 6.0 kg

Bellied cellular volcanic rock

(Noblite G 200 EC) 20.0 kg

Expandable graphite (for example GHL PX 95 from LÜH) 5.0 kg

Silica (e.g., Aktisil EM from Hoffmann-Minerals) 6.0 kg

Aluminum trihydrate 2.0 kg

Surfactant solution 2% (eg Tegopren 5840 from Evonik) 3.0 kg

Claims

claims

Intumescent heat-insulating fire-resistant molded part for fire protection, with a calorific value according to DIN EN 1716 of 3 MJ / kg or less,

characterized,

that it contains at least one light filler, expandable graphite, a hybrid inorganic-inorganic binder and one or more minerals and that it contains fibers and / or mineral needles.

Molding according to claim 1,

characterized,

the lightweight filler has a bulk density of less than 400 kg / m ³ , in particular less than 300 kg / m ³ , particularly preferably less than 200 kg / m ³ .

Molding according to claim 1,

characterized,

that it has a thermal conductivity of 0.07 W / mK or less at 10 ° C.

Molding according to claim 1,

characterized,

that it contains a dehydrating mineral, in particular aluminum trihydrate.

Molding according to claim 1,

characterized,

that it contains a uniform type of fibers or a mixture of different fibers, in particular mineral fibers, with a softening point of 500 ° C or higher and / or mineral needles.

Molding according to claim 1,

marked by

the following composition

Light filler 35 to 75% by weight

Fibers 0bisl5Gew .-% Expanded graphite 0.5 to 15% by weight

Hybrid binder 1.5 to 20% by weight

mineral needles 0 to 30% by weight

Minerals 1 to 18 wt .-%.

Molding according to claim 1,

characterized,

that it is designed layered as a thermal insulation board, fire protection board, standard stone or brick, in particular with different proportions of expanded graphite.

8. A method for producing a thermally insulating molding according to one of the preceding claims,

characterized,

that it is produced by shaping a plastic mass and drying and thermal treatment.

9. The method according to claim 8,

characterized,

the composition contains at least one light filler, a hybrid binder, a dehydrating mineral, optionally fibers and / or mineral needles, and water,

wherein one uses as light filler blown closed cell volcanic rock, which is equipped with a superficial water protection layer, and / or glass hollow spheres,

wherein at least one organic-inorganic hybrid binder containing silica and an organic polymer is used as the binder, and

wherein the mass contains expandable graphite as an intumescent component, aluminum trihydrate, kaolin or kaolinite and optionally silicon dioxide, preferably silica sol, in particular silica.

10. The method according to claim 8,

characterized,

that the hybrid binder used in the plastic mass contains particles which in turn are composed of amorphous silica particles which contain as binders an acrylate-based polymer, in particular n-butyl acrylate and methyl methacrylate and / or latex.

Method according to claim 8,

characterized,

in that a modified silica is used in the plastic mass, which contains silica-kaolinite particles whose surface is coated with a wetting agent, in particular a silane.

Method according to claim 8,

characterized,

that the plastic mass has the following composition:

Light filler 15 to 35% by weight

Expanded graphite 0.5 to 12% by weight

Hybrid binder 1 to 15% by weight

Fibers 0.5 to 5% by weight

modified silica ibis 15% by weight

Aluminum trihydrate 1 to 15% by weight

mineral needles 0.5 to 15% by weight

Rest of water.