Patent Description:
<CIT> teaches geopolymer aggregates and their use in a variety of applications. Furthermore, <CIT> teaches that the addition of geopolymer or its composite as prepared with various types of athermanous additives makes it possible to maintain the polymer foam's self-extinguishing and mechanical properties in the same range as in an expanded polymer without addition of filler or any other athermanous additive, while at the same time the thermal conductivity can be decreased significantly. This is possible because the geopolymer itself gives fire resistance, and further encapsulates the particles of athermanous additive, especially of those additives that are based on carbon or mineral, and separates them from any disadvantageous interactions with the flame, the polymer, or the brominated flame retardant. The presence of geopolymer decreases thermal conductivity, because of its own heat radiation scattering effect.

Geopolymers are inorganic amorphous polymers with a three-dimensional, crosslinked alumina silicate structure, consisting of Si-O-Al-O bonds. The structure may be created in a sol-gel method by metal alkali activation of alumina silicate precursors. The formed gel product contains alkaline cations which compensate for the deficit charges associated with the aluminium-for-silicon substitution. During the dissolution of alumina silicate precursor and gel formation, an intermediate, aluminium rich phase is first formed which then gives way to a more stable, silicon-rich product. Under these conditions, free SiO<NUM> and AlO<NUM>- tetrahedral units are generated and are linked to yield polymeric precursors by sharing all oxygen atoms between two tetrahedral units, while water molecules are released. The tetrahedral units are balanced by group I or II cations (Na+, K+, Li+, Ca<NUM>+, Ba<NUM>+, NH<NUM>+, H<NUM>O+, which are present in the framework cavities and balance the negative charge of Al<NUM>+ in tetrahedral coordination, i.e. AlO<NUM>-). This material was early investigated and developed by Davidovits after various catastrophic fire incidents in France in the <NUM>. The term "geopolymer" was coined in view of the transformation of mineral polymers from amorphous to crystalline reaction through a geochemical process at low temperature and short curing time. Geopolymers are represented by the general chemical formula of Mn[-(Si-O<NUM>)z-Al-O]n · w H<NUM>O, in which M is an alkali metal, z is <NUM>, <NUM> or <NUM> and n is the degree of polymerization. Based on the Si/Al molar ratio, three monomeric units can be defined: polysialate (Si/Al = <NUM>; Si-O-Al-O-), polysialatesiloxo (Si/Al = <NUM>; Si-O-Al-O-Si-O-) and polysialatedisiloxo (Si/Al = <NUM>; Si-O-Al-O-Si-O-Si-O-).

<CIT> teaches a product formed from a first material including a geopolymer resin material, a geopolymer resin, or a combination thereof by contacting the first material with a fluid and removing at least some of the fluid to yield a product. The first material may be formed by heating and/or ageing an initial geopolymer resin material to yield the first material before contacting the first material with the fluid.

<NPL> reports photoactive nano-oxide composites in a geopolymer matrix.

<NPL>, teaches heterogeneous redox catalysts based on geopolymer aluminosilicate materials.

<CIT> teaches geopolymers based essentially on two different phases, namely silicates. <CIT> discloses a method for making geopolymer cementitious binder compositions for cementitious products.

<CIT> discloses nanocomposite compositions based on expandable thermoplastic polymers which comprise an athermanous filler comprising nano-scaled graphene plates with a thickness (orthogonal to the graphene sheet) not greater than <NUM>, an average dimension (length, width, or diameter) not greater than <NUM> and a surface area ><NUM><NUM>/g.

<CIT> teaches thermoinsulating expanded articles with improved resistance to solar irradiation, which comprise an expanded polymeric matrix, obtained by expansion and sintering of beads/granules of a vinyl aromatic (co) polymer, in whose interior a filler is homogeneously dispersed, which comprises at least one athermanous material selected from coke, graphite and carbon black and optionally an active inorganic additive within the wave-lengths ranging from <NUM> to <NUM>,<NUM>-<NUM>.

The structure of geopolymers can be amorphous or semi crystalline, depending on the condensation temperature. Amorphous polymers are obtained at <NUM>-<NUM>, whereas semicrystalline polymers are obtained in the range <NUM>-<NUM>. This class of materials demonstrates ceramic-like properties, including extreme fire resistance. Geopolymers can be amorphous or crystalline materials. They possess a microstructure on a nanometre scale (as observed by TEM and measured by mercury porosimetry) which comprises small aluminosilicate clusters with pores dispersed within a highly porous network. The cluster size is typically between <NUM> and <NUM>. The synthesis of geopolymers from aluminosilicate materials takes place by the so-called geopolymerization process, which involves polycondensation phenomena of aluminate and silicate groups, with formation of Si-O-Al type bonds.

On the other hand, polymers such as vinyl aromatic polymers are known and are used for the preparation of expanded (foamed) products that are adopted in a variety of applications, of which the most important one is for thermal insulation. This is why there is a continuously increasing demand for polymers compositions (in particular when the composition is an expanded vinyl aromatic polymer composition) with low thermal conductivity as well as good mechanical and self-extinguishing properties.

One of the solutions to decrease the thermal conductivity of expanded vinyl polymers is the addition of athermanous additives. However, the presence of athermanous additives often leads to a deterioration of the self-extinguishing and mechanical properties of the expanded vinyl aromatic polymer (i.e. foam). Consequently, a higher concentration of flame retardant must be used to achieve suitable performance for passing the flammability test according to the German industry standard DIN <NUM> (B1, B2) or European standard EN ISO <NUM>-<NUM>. Further, when using as athermanous additive certain types of carbon black having a highly developed active surface, such as a BET surface of above <NUM><NUM>/g, or poor forms of graphite containing graphitic carbon in a concentration of well below <NUM> % and having a high content of sulphur and ash, the self-extinguishing properties are insufficient in order to pass DIN <NUM> (B1, B2) or at least EN ISO <NUM>-<NUM> (which is a less demanding test).

On the other hand, the presence of small amounts of athermanous additives of the heat scatterer type, e.g. minerals (such as silicas, calcium phosphates and minerals with perovskite structure) does not cause a substantial deterioration of the flame retarded polymer foam's self-extinguishing properties. Rather, these properties are improved, but the decrease of the foam's thermal conductivity is not as pronounced as it would be in the case of foams comprising carbon-based additives, i.e. comprising athermanous additives of the heat absorber or of the heat reflector type (in particular carbon blacks and/or graphites).

Finally, there are certain types of additives, such as carbon-based athermanous additives of the heat absorber or heat reflector type (especially carbon black and graphite), that have properties that make these additives, by themselves, unsuitable for use in expandable vinyl aromatic polymers and expanded vinyl aromatic polymer foams. Thus, <CIT> relates to the use of a combination of a) a mineral component containing silica, calcium phosphate, or mixtures thereof, and b) carbon black, for decreasing the thermal conductivity of foamed vinyl aromatic polymer.

It was the object of the present invention to provide constituents for vinyl aromatic polymer compositions, which constituents improve thermal conductivity, of a vinyl aromatic foam, without adversely affecting mechanical and other product properties, such as self-extinguishing.

It has now surprisingly been found that these problems with expandable vinyl aromatic polymers can be overcome by the incorporation of a modified geopolymer, preferably in combination with (preferably athermanous) additive, or of a novel modified geopolymer composite comprising (preferably athermanous) additive.

The modified geopolymer and modified geopolymer composite, as used according to the present invention, may be prepared by a process for the production of a modified geopolymer or modified geopolymer composite, the process comprising.

It has been found in accordance with the present invention that the use of:.

Thus, the addition of modified geopolymer or its composite as prepared with various types of additives (preferably athermanous additives) makes it possible to maintain the foam's self-extinguishing and mechanical properties in the same range as in an expanded polymer without addition of filler or any other (athermanous) additive, while at the same time the thermal conductivity can be decreased significantly. This is possible because the modified geopolymer itself gives fire resistance, and further encapsulates the particles of additive, if present, especially of those additives based on carbon or mineral, and separates them from any disadvantageous interactions with the flame, the polymer, or the flame retardant. The presence of modified geopolymer further decreases thermal conductivity, because of its own heat radiation scattering effect. Moreover, the versatility of modified geopolymer allows it to incorporate a variety of compounds such as phosphorus compounds and nitrogen compounds which may contribute to fire resistance, whereas incorporated compounds such as copper compounds, silver compounds, zinc compounds, tin compounds and magnesium compounds may contribute to the composition's resistance to any microbial growth within or on such composition.

Also, the modification of geopolymer or geopolymer composite gives materials having a better stability, such as improved adhesion to the polymers into which they are incorporated in accordance with the present invention.

Moreover, the present invention allows one to use certain types of additives that would otherwise be unsuitable for use in expandable vinyl aromatic polymers and expanded vinyl aromatic polymer foams.

The present invention in accordance with the claims has the following aspects:.

The modified geopolymer (composite) and process for the production thereof, as disclosed below, are not encompassed by the claims.

The modified geopolymer, as used according to the present invention, may be produced in several process steps in which if needed additive (such as coke or anthracite or graphene oxide or metal oxide or sulfide or metal) during the process of production becomes encapsulated into the matrix of the geopolymer by chemical and physical bonding. This type of geopolymer is suitable for performing a self-extinguishing action and further reducing the thermal conductivity properties of vinyl aromatic polymers and expanded foam products made thereof. Additionally, it was found that the self-extinguishing effect could be enhanced when a relatively small amount of modifier, e.g. a phosphorus compound such as phosphoric acid or ammonium polyphosphate, is used to alter the surface of geopolymer or geopolymer composite. It was found that this surface modification can help to reduce the amount of brominated flame retardant or completely eliminate the need to use any brominated flame retardant.

It was further found that better self-extinguishing properties are obtained when the content of cations such as sodium or potassium is limited below <NUM> ppm in modified geopolymer or modified geopolymer composite, when modified geopolymer or modified geopolymer composite are added to the product in the co-presence of brominated flame retardant. This is because especially sodium accelerates the thermal decomposition of brominated molecules, with creation of bromic acid and salt, respectively.

Also, geopolymer or geopolymer composite suspended in water can be ion exchanged. In was discovered that during or after the filtration process or following the dealkalization in which exchange of sodium or potassium cations by hydrogen cations is realized, or alternative to such dealkalization, an ion exchange can be performed. Such ion-exchanged particles of modified geopolymer or of modified geopolymer composite (incorporating ions of Ag, Zn, Cu, Cu, Ni, Sn, Mg) further improves the reduction of thermal conductivity of polymeric foams, acting additionally as antimicrobial agent.

In an additional aspect, it has been found that the use of a modified geopolymer or a modified geopolymer composite prepared from a mixture of aluminosilicate precursor and phosphoaluminate further enhances the self-extinguishing effect in vinyl aromatic polymer foams.

The modified geopolymer or modified geopolymer composite, as used according to the present invention, may be prepared in a process comprising.

The process further comprises modification with one or more water-soluble compounds, and h) obtaining the modified geopolymer or modified geopolymer composite.

Step a) is preferably performed by mixing of precursor for aluminate and silicate, to form a sol-gel, wherein the mixing is under alkaline conditions.

It is preferred that the mixing in step a) comprises the mixing of an aluminosilicate, a phosphoaluminate, an alkaline silicate and/or an alkaline aluminate. Thus, in a first step, the sol-gel is prepared, for instance from a mixture of aluminosilicate precursor and activator such as sodium aluminate or sodium disilicate, with addition of water. It is also preferred in the process to use sodium disilicate or sodium aluminate or their potassium analogues. Especially, it is preferred that the alkaline solution is a water-diluted sodium aluminate or sodium disilicate, in particular sodium aluminate.

It is further preferred that the mixing in step a) involves one or more materials selected from the group consisting of dehydroxylated kaolinite, metakaolin, metakaolinite, fly ash, furnace slag, red mud, thermal silica, fumed silica, halloysite, mine tailings, pozzolan, kaolin, and building residues,.

It is further preferred that one or more of step a) and step c) comprises mixing in a conical screw mixer. Preferably, both step a) and step c) comprise mixing in a conical screw mixer.

The mixing may be a high seed mixing of an aluminosilicate component with an alkaline silicate solution prepared from the sodium or potassium water glass or sodium aluminate or sodium disilicate or phosphoaluminate or mixture thereof, to form the sol-gel. Preferably, the activator is in particular sodium silicate water solution (so called water glass), dry sodium silicate, sodium disilicate, calcium silicate, potassium silicate, sodium aluminate, calcium aluminate, or potassium aluminate.

The weight ratio of alkali silicate or aluminosilicate solution to the metakaolin or fly ash or silica is preferably at most <NUM>/<NUM>, more preferably at most <NUM>/<NUM>, most preferably about <NUM>/<NUM>. The weight ratio depends strictly on the molar ratio of Si/Al in the final modified geopolymer. The molar ratio of silicon versus aluminium determines the chemical structures, properties and thereby the field of application of the resultant modified geopolymers. Modified geopolymers can be classified in term of their chemical structure, taking the Si/Al molar ratio into account. If the molar ratio is <NUM>, the geopolymer consists of (-Si-O-Al-O-) repeating monomeric units - poly(sialate), in the case of Si/Al = <NUM>, the geopolymer structures are enriched in additional silica tetrahedron units - (-Si-O-Al-O-Si-O) - poly(sialate-siloxo). A participation of the silica tetrahedron units into a chain increased with an increasing level of Si incorporation. Thus, a molar ratio equal to <NUM> provides (-Si-O-Al-O-Si-O-Si-O) structures - poly(sialate-disiloxo), whereas a molar ratio above <NUM> results in more rigid three dimensional silico-aluminate structures.

Regarding the applications, geopolymers may be categorized as follows: Si/Al = <NUM> (typically bricks, ceramics, fire protection); Si/Al = <NUM> (typically geopolymer cement, concrete, radioactive encapsulation); Si/Al = <NUM> (typically heat resistance composites, foundry equipment, fibre glass composites); Si/Al > <NUM> (typically sealants for industry); <NUM> < Si/Al < <NUM> (typically fire and heat resistance fibre composites).

Changes in the Si/Al ratio can drastically affect the flexibility of obtained modified geopolymer. The smaller the value of the Si/Al ratio, the more flexible is the modified geopolymer used according to the present invention. This was especially observed in the case of a Si/Al ratio of about <NUM>, where aluminosilicates formed "more flexible" poly(sialate) structures, as compared to a 3D network of poly(sialate-siloxo) and poly(sialate-disiloxo) exhibiting shrinkage and cracks. From the literature is know that such flexibility was observed when the molar Si/Al ratio exceeds <NUM>, with the much higher content of Si in matrix constituents.

Mixing is typically carried out at ambient temperature for a minimum of <NUM> minute and a maximum of <NUM> minutes. In this step after the addition of the alkaline silicate solution (so called water glass), silane may preferably be added to the gel, in order to improve adhesion of geopolymer in particular to carbon-based athermanous additives and later to the filled polymer. The concentration of silane is preferably in the range of from <NUM> to <NUM> wt. %, more preferably in the range of from <NUM> to <NUM> wt. %, most preferably from <NUM> to <NUM> wt.

Geopolymer or geopolymer composite may thus be modified by reaction with coupling agents, to obtain better adhesion to the vinyl aromatic expandable polymers. Different coupling agents may be used, depending on when the addition during the preparation of the geopolymer or the geopolymer composite takes place. However, this depends on the type of geopolymer used and the type of additive within the geopolymer composite.

Whilst various silanes can be used, the best adhesion performance is achieved when using aminopropyltriethoxysilane (e.g. Dynasylan AMEO from Evonik), aminopropyltrimethoxysilane (e.g. Dynasylan AMMO from Evonik), phenyltriethoxysilane (e.g. Dynasylan <NUM> from Evonik), <NUM>-methacryloxypropyltrimethoxysilane (e.g. Dynasylan MEMO form Evonik) and vinyltrimethoxysilane (e.g. Dynasylan VTMO from Evonik).

Thus, it is very preferred that silane is added, preferably in step a). When the silane is e.g. <NUM>-methacryloxypropyltrimethoxysilane, the process further preferably comprises the addition of a butadiene latex in one or more of steps a), b) and c) (preferably, the addition of the butadiene latex is in one or more of steps a) and step b)).

It is further preferred that silane is added to the geopolymer composite, after optional step e) and preferably after step h), and the silane is preferably selected from aminopropyltriethoxysilane, aminopropyltrimethoxysilane, phenyltriethoxysilane, <NUM>-methacryloxypropyltrimethoxysilane, and mixtures thereof.

It is most preferred that silane is added in an amount of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. %, most preferably from <NUM> to <NUM> wt. %, based on the weight of modified geopolymer or modified geopolymer composite.

Also, it is preferred that the additive is an athermanous additive, preferably selected from the group consisting of.

It is very much preferred that the process for the preparation of modified geopolymer (composite) includes optional dealkalization step e). Preferably, step e) comprises the addition of an acid solution, and subsequent drying. In particular, step e) comprises addition of an acid solution, washing with water, and subsequent drying.

Moreover, it is preferred that the modification with one or more water-soluble compounds is in step f), step g) and/or step h). Preferably, the modification is in step g).

The water-soluble compound is preferably selected from phosphorus compounds, nitrogen compounds, copper compounds, silver compounds, zinc compounds, tin compounds, and magnesium compounds. Preferably, the modification is with a phosphorus compound, in particular with a phosphorus compound selected from phosphoric acid and ammonium polyphosphate.

Also, step f) comprises preferably repulpation (re-forming of a pulp), more preferably the repulpation is with demineralized water or an acid solution, in particular the repulpation is with an acid solution.

Moreover, step f) preferably comprises a membrane squeeze.

It is further preferred that step g) comprises repulpation, more preferably the repulpation is with demineralized water.

Advantageously, dissolvers with high speed and mixing intensity up to <NUM> rpm are used for any dealkalization and repulpation, to better remove metal cations from the geopolymer matrix.

Preferably, two steps of membrane slurry filtration are performed, where the second step takes place after a repulpation step. Further sequences of i) repulpation and ii) filtration can be performed, to further reduce the content of undesired metal cation.

The drying in step d) may comprise two drying steps. Preferably, the first drying is at a temperature within a range of from <NUM> to <NUM>, and the second drying is at a temperature within a range of from <NUM> to <NUM>.

Furthermore, the milling in step d) preferably comprises jet milling, and the jet milling process is performed with the use of hot air, to increase milling capacity by increasing the amount of adiabatic energy.

The water content of the final modified geopolymer or modified geopolymer composite produced is preferably in a range of from <NUM> to <NUM> wt. %, preferably <NUM> to <NUM> wt. %, more preferably <NUM> to <NUM> wt.

Modified geopolymer or modified geopolymer composite as produced may be used according to the present invention together with brominated flame retardant. Because brominated flame retardants have limited compatibility with products having a certain sodium content, the sodium content of the modified geopolymer or modified geopolymer composite is therefore less than <NUM> ppm, more preferably less than <NUM> ppm, in particular less than <NUM> ppm, such as less than <NUM> ppm, or even less than <NUM> ppm, each calculated on dry mass.

If the modified geopolymer or modified geopolymer composite, when used according to the present invention, is not used together with brominated flame retardant, then the sodium content need not necessarily be low. In this embodiment of the claimed use, the sodium content of the modified geopolymer or modified geopolymer composite is less than <NUM>,<NUM> ppm, more preferably less than <NUM>,<NUM> ppm, in particular less than <NUM>,<NUM> ppm, each calculated on dry mass.

The process for the production of a modified geopolymer or a modified geopolymer composite may thus proceed as follows:.

Again, step a) is preferably performed by mixing of precursor for aluminate and silicate, to form a sol-gel, wherein the mixing is under alkaline conditions.

The first step a) may be a high speed mixing and dissolution of an amorphous phase of aluminosilicate precursor and/or phosphoaluminate component in an alkaline solution prepared from a water solution of sodium hydroxide and silicon dioxide (water glass) or a water solution of sodium disilicate or a water solution of sodium aluminate with or without addition of phosphoaluminate.

The activator may instead of sodium water glass be sodium aluminate or sodium disilicate or a mixture thereof. Also, the sol-gel may be prepared from a mixture of aluminosilicate precursor and activator such as sodium aluminate or sodium disilicate, with addition of water.

Particularly preferred precursors are dehydroxylated kaolinite, metakaolin or metakaolinite, but also fly ash, furnace slag, red mud, thermal silica, fumed silica, halloysite and a mixture thereof.

After activation and dissolution, the ortho-sialate monomer [(HO)<NUM>-Si-O-Al-(OH)<NUM>] polycondensates and forms a sol-gel, so called "gel". The mixing is in a third step c) continued. Preferably, in step b), there is an addition of an additive, in micro or in nano powder form. During step a), b) or c), water can be introduced as a viscosity modification additive, and/or silane and/or latex as adhesion modifiers.

Once the curing (geopolymerization) process has substantially come to the stage that the material is partially solidified, drying of the geopolymer blocks in a fourth step d) evaporates excess of water. Some water may deliberately be kept in the material, preferably up to <NUM> wt. %, to improve material grindability (increase capacity) during the jet milling process with the use of hot air, preferably at a temperature in a range of from <NUM> to <NUM>. Drying may be performed in a tunnel dryer, where blocks of material are placed on steel plates stacked as columns. The drying process is typically performed in two steps. The first step takes place at a lower temperature e.g. in the range of <NUM> to <NUM>; in this step further geopolymerization takes place with some water evaporation of about <NUM> to <NUM> % of material mass. The second step is at a temperature e.g. in a range of from <NUM> to <NUM>, to suitably reduce the water content to a level of <NUM> to <NUM> wt. % in the material. After that, "dry" blocks are crushed, to form particles of a size of a few millimetres (in the d50 range of below <NUM> to <NUM>). Then this granulate is jet milled, preferably with the use of hot air, to obtain a suitable particle size and high capacity per hour of production. Preferably, the average particle size (D50) is in the range of <NUM> to <NUM>.

The fifth and optional step e) is a dealkalization, to remove cations from the geopolymer matrix, preferably by addition of concentrated hydrochloric acid to the particles of geopolymer or geopolymer composite, as suspended in water. The reaction is preferably performed within <NUM> and in a temperature range of from <NUM> to <NUM> in a heated/cooled dissolver, with an agitation speed in the range of <NUM> to <NUM> rpm. Reaction typically results in the release of hydrogen sulphide and sulphur dioxide, as well as a pH change in the range of <NUM>-<NUM>. Additionally, the viscosity of the slurry increases significantly due to change of particles surface and geopolymer interaction with water. Process water having a conductivity below <NUM>/cm may be used for the dealkalization step.

Subsequently in step f), the first step membrane filtration is performed and finished with an inside press pressure in the range of <NUM>-<NUM> bar; received filtrate conductivity is typically in the range of <NUM>,<NUM> to <NUM>,<NUM>/cm. Afterwards, the salts are washed with the use of so called "process water", having a conductivity of below <NUM>/cm and finally after minimum <NUM> minutes receiving the filtrate with a conductivity below <NUM>/cm. At the end, a pressure (<NUM>-<NUM> bar) membrane squeeze is applied, to increase the solids content in the precipitate cake from <NUM> up to <NUM> wt. This step avoids a strong thixotropic effect which would otherwise make granulation of the precipitated cake (to transport it to the repulpation stage) difficult, thus, the water content must be reduced.

The "cake" may then in step g) be granulated and suspended in a weak acid solution. An acidic suspension of a geopolymer or a geopolymer composite is affected in a dissolver, equipped with two types of agitators for avoiding agglomeration of suspended precipitate on the dissolver walls, a high speed (<NUM>-<NUM> rpm) agitator and a low speed (<NUM>-<NUM> rpm) agitator. <NUM> is typically enough to perform this repulpation step. Different acids could be used, such as hydrochloric acid, phosphoric acid, nitric acid or sulphuric acid. Organic acids may also be used. The elution could be performed as more repulpation - filtration steps, to improve reduction of sodium and other metal cations, especially if a sodium content in the final material below <NUM> ppm is desired. In some other applications, when the modified geopolymer or modified geopolymer composite is not used together with brominated flame retardants at the processing temperatures, such repeated elution may not be necessary. This depends on the final application of the modified geopolymer or modified geopolymer composite.

In a seventh step g) of the process, a second step of filtration is necessary. The slurry, which after repulpation has a pH in the range of <NUM>-<NUM>, may be pumped to the membrane press and filtrated, ending with an inside press pressure in the range of <NUM>-<NUM> bars. Any remaining acid and salts may then be washed, giving a filtrate with a conductivity below <NUM>/cm. Preferably, cold demineralized water is used, to reduce production cost related to water heating energy. However, with hot water having a temperature in a range of from <NUM> to <NUM>, it is possible to accelerate elution and to reduce water consumption. Preferably, further salt elution is performed after the second filtration step, with the use of demineralised water.

In step g), the surface modification may be performed, for instance by treating the precipitated cake with a demineralized water solution of acid, preferably phosphoric acid or phosphates or its salts or polyphosphates or its salts. The surface modification by phosphorus and/or nitrogen based compounds may thus be performed with the use of an aqueous solution. The aqueous solution of the phosphorus and/or nitrogen based compound is transferred in one or more cycles through the filter press. If this step is needed because of the application of the resultant modified geopolymer or modified geopolymer composite, it is often performed before the membrane squeeze and vacuum drying in the membrane filter press.

The modification can alternatively be an ion exchange, with the use of a water solution of a salt such as copper chloride, silver nitrate, or magnesium sulphate, or some other salt which is soluble in cold or hot water.

Modified geopolymer or modified geopolymer composite in form of precipitated cake in step h) is e.g. membrane squeezed, to increase the solids content up to <NUM> wt. %, and heated by the relatively low steam pressure of about <NUM> MPa to a temperature in the range of from <NUM> to <NUM>. Thus, the vacuum drying may be performed in a membrane filter press, using steam for heating. In cycles, vacuum is applied and the pressure in the press is reduced to below <NUM> mbar. The cycles depend on the cake's thickness and the preferred temperature. Preferably, a cycling such as heating to a temperature of above <NUM> is performed, and then the pressure is reduced to below <NUM> mbar. The vacuum cycle is finished when the temperature drops below <NUM> and again heating is applied. The drying step is finished when the water content in the precipitate is in the range of <NUM> to <NUM> wt. After that, the cake is removed from the press automatically and granulated for example with the use of a cum crusher, or a screw crusher, or a hammer mill, or any other type of crusher, followed by deagglomeration in an impact mill with a rotor speed in the range e.g. from <NUM> to <NUM> rpm. After impact milling, the fine powder is recovered and ready for use.

Preferably, the additive as used in combination with modified geopolymer or as incorporated into modified geopolymer composite is one or more selected from the group consisting of.

The second and optional step is thus the incorporation of additives, preferably one or more athermanous additives. Preferably such additive could be carbon black, graphite, coke, anthracite, graphite oxide.

In particular, the following cokes could be used: petroleum coke, metallurgical coke, shot coke, sponge coke, fluid coke, beaded coke, needle coke, pitch coke or anode coke.

In particular, the following anthracites could be used: green anthracite, semianthracite, anthracite, meta-anthracite or gas calcined anthracite and electrically calcined anthracite or dealkalized and desulphurized types of anthracite.

Additionally, other types of carbon based additive are possible, such as sea coal, graphene oxide, nanotubes or carbon fibers.

In a preferred embodiment of all aspects of the invention, additive a. is selected from coke, graphitized carbon black, graphite oxides, graphite, anthracite, graphene oxide, and nano-graphite and carbon nanotubes (single and multilayer). Most preferred in all embodiments of the invention is that the athermanous additive is a carbon athermanous additive selected from graphene oxide, nano-graphite, and mixtures thereof.

Alternatively, metal oxides could be added, preferably, titanium dioxide, iron oxide, chromium oxide, silicon oxide or nickel oxide or their nanoforms.

Further alternatively, metal sulfides such as tungsten sulfide or nickel sulfide are possible as additives.

The incorporation of ilmenite, rutile, perovskite mineral, barium sulphate, chamotte, fumed silica, fly ashes, hydromagnesite/huntite mineral or the mixture of all or minimum two additives to the forming geopolymer gel is likewise preferred.

After (optional) additive incorporation, the high shear mixing is continued, and further geopolymerization takes place, and additive is physically encapsulated or chemically reacted by growing chains of geopolymer, thus the surface becomes modified.

The additive, or a minimum of two additives, is preferably added in an amount of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. %, most preferably from <NUM> to <NUM> wt. % depending on the type of the additive or additive mixture, based on the weight of geopolymer composite. Different mixtures and different ratios between the additives are possible. After addition of additive, or mixture of at least two additives from the above proposed, the thixotropic gel is further high speed mixed, to result in a homogenous consistence. Water can then be added, to regulate the final viscosity. The water is added in a preferred ratio from <NUM>/<NUM> to <NUM>/<NUM> or depending on additive type and its bulk density as well as hydrophilic properties and specific surface.

For the geopolymer composite synthesis the following athermanous additives are preferably used:.

Preferably, the process specifically proceeds as follows:
Mixing of the aluminosilicate component, e.g. a dehydroxylated kaolinite (metakaolin or metakaolinite) mixed, with furnace slag, or fly ash, or thermal silica, in a weight ratio range of from <NUM>/<NUM> to <NUM>/<NUM>, preferably from <NUM>/<NUM> to <NUM>/<NUM> in a water alkali solution of silicate, generally sodium or potassium silicate, or in an alkaline solution prepared from water and sodium aluminate or sodium disilicate as starting materials. In the high speed mixing process, used to prepare the modified geopolymer as used according to the present invention, the dissolution and hydrolysis of the aluminosilicate component takes place in alkali solution and results in the formation of [Mz(AlO<NUM>)x(SiO<NUM>)yMOH·H<NUM>O] gel. The dissolution time depends on amorphous silica content in aluminosilicate component, fly ash and other additives, temperature as well as type of mixing. The polymerization can be described by the following equations: <MAT> <MAT> <MAT>.

The formation of gel is the dominant step in the geopolymerization reaction and it highly depends on the mixing type, which takes place after dissolution. The mixing is continued for a suitable time period to achieve the best dissolution of aluminosilicate and is preferably performed in a high speed, high shear mixer. The mixing time should be adjusted depending on the amount of loaded components and is preferably in a range of from <NUM> to <NUM>.

It was found that conical screw mixers with the central screw agitator used in various applications are particularly suitable to prepare homogenous geopolymeric gel. In the production, a quick batching stage is performed, thus it is required to provide high speed mixing and to prepare the gel within <NUM> minute of even less. To achieve such conditions, a mixing speed in the range from <NUM> to <NUM> rpm, preferably from <NUM> to <NUM> rpm, more preferably from <NUM> to <NUM> rpm may be used. The other favourable feature of such mixers is the possibility for a full opening of the bottom and emptying of the mixer off the very viscous melt, thanks to the agitator's movement directly into the mould.

The filled geopolymer in the form of a thixotropic gel is thus removed from a conical mixer because of the agitator movement, directly to the moulds. The vibration is applied simultaneously to level the thixotropic melt and the mould is closed immediately, to prevent water evaporation. Closed moulds are then transported to the curing room. A transport system and a curing system similar to that used commonly in the concrete industry could be applied. During this process, the geopolymer polymerization continues. Also, the time of geopolymer polymerization is important, thus the curing is preferably continued during a minimum of <NUM> and a maximum of <NUM>, and most preferable is a curing time of <NUM>. After this process, the ready blocks of geopolymer contain from <NUM> to <NUM> wt. % or more of water, depending on how much excess water was added to regulate the gel viscosity. It was also found that excess of water significantly influences the curing time. The curing time is also strictly related to the molar ratio of Si/Al. At a lower ratio Si/Al≤<NUM> or <<NUM>, a longer curing time was observed. The reaction accelerates significantly when Si/Al><NUM>.

After the curing time, moulds are dismantled and blocks of geopolymer or geopolymer composite are transported to the drying stage. On the production scale, the ready blocks are stored on steel plates, then placed on racks in columns, in closed tunnel dryer chambers wherein warm air having a temperature ranging from <NUM> to <NUM>, most preferably from <NUM> to <NUM>, is driven from the side through the racks and excess water is removed slowly over <NUM> for example. Normally, from <NUM> to <NUM> wt. % of water can be removed from the geopolymer blocks during <NUM> of drying in a temperature range of <NUM> to <NUM>. The process can be prolonged according to needs and size of the blocks or water excess which should be removed before the grinding process. In particularly, a two-step drying process is preferred. To finalize the geopolymerization and avoid formation of zeolites during <NUM> to <NUM>, the temperature is kept in a range of <NUM>-<NUM>, more preferably <NUM>-<NUM>. After first-step drying is finished, the temperature is raised above <NUM> and kept in a range of <NUM> to <NUM>, preferably <NUM>, in this stage we do not exclude partial formation of zeolites in the geopolymeric structure.

After drying of the blocks, the preliminary milling of these blocks is performed, to form aggregate with a particle size of from <NUM> to <NUM>. A larger size is possible if required. After this, the suitable particle size can be obtained by using various types of mills, preferably ball mills, fine impact mills, table roller mills or jet mills preferably; it is preferred that the mill should be equipped with a particle size classifier. A preferred particle size is an average particle size (D50) in a range of from <NUM> to <NUM>, D90 in a range of from <NUM> to <NUM>, D99 in a range of from <NUM> to <NUM>, D100 in a range of from <NUM> to <NUM> and D10 in range of <NUM> to <NUM>; or the particles can be milled only preliminarily to obtain particles sizes in a range of from <NUM> to <NUM>.

A further stage is the optional dealkalization, which consist of a reaction of metal cations which are present in the geopolymeric structure with the hydrochloric acid as present in the aqueous suspension. Other acids may be used, such as sulphuric acid, phosphoric acid, nitric acid, carbonate acid or acetic acid. The dealkalization process is performed in the jacketed agitated reactor equipped with a frame stirrer to avoid material sticking to the reactor walls, high shear dissolver to avoid agglomeration, thermocouple, pH and ion conductivity meter. A mixing speed in the range of <NUM> to <NUM> rpm is used.

As a first part of this dealkalization step, process water with a conductivity below <NUM>/cm, preferably below <NUM>/cm, and more preferably below <NUM>/cm or demineralized water with conductivity below <NUM>/cm, and geopolymer or geopolymer composite powder (with a particle size of from <NUM> to <NUM>) are poured into the reactor while stirring vigorously. A suitable mass ratio of geopolymer or geopolymer composite powder to water is in the range from <NUM>:<NUM> to <NUM>:<NUM>, more preferable from <NUM>:<NUM> to <NUM>:<NUM> and most preferable from <NUM>:<NUM> to <NUM>:<NUM>.

The second part of this dealkalization step is the addition of concentrated hydrochloric acid to the mixture, preferably about <NUM>% concentrated. Before the acid addition, the pH value resulting from the addition of geopolymer or geopolymer powder is in the range of <NUM>-<NUM>, more preferably the pH value is in the range of <NUM>-<NUM> and conductivity of approx. <NUM>,<NUM> to <NUM>,<NUM>/cm. After addition of hydrochloric acid and a reaction time of about <NUM>, the resulting pH value is in a range of <NUM>-<NUM> and conductivity increases significantly, to <NUM>,<NUM> to <NUM>,<NUM>/cm, more preferably from <NUM>,<NUM> to <NUM>,<NUM>/cm. The dealkalization process is typically performed at a temperature in the range of <NUM>-<NUM>, more preferable of <NUM>-<NUM> and most preferable of <NUM>-<NUM>. The temperature increases after acid treatment, and then it decreases gradually.

After dealkalization, the resulting viscous suspension, having a temperature of <NUM>-<NUM>, is pumped to the first step of filtration, f). The amount of process or demineralized water to wash the filtrated cake is in the range of <NUM> to <NUM> mass excess per weight of the mass in the filter press. Filtration is continued, until the pressure inside the press rises to the level of <NUM> to <NUM> bar, preferably <NUM> bar. The starting filtrate's pH value is the range of <NUM> to <NUM> and conductivity from <NUM>,<NUM> to <NUM>,<NUM>/cm. Filtration is continued over a minimum of <NUM> minutes and after this time, the filtrate's pH value increases to <NUM>-<NUM> and conductivity decreases to below <NUM>/cm, preferably below <NUM>/cm, which is recognized as the washing end, thus the membrane squeeze is applied, preferably with a pressure in the range from <NUM> to <NUM> bar, more preferably from <NUM> to <NUM> bar. The precipitated cake, with a dry mass content in the range of <NUM>-<NUM> wt. %, preferably <NUM>-<NUM> wt. %, falls to the screw granulator hopper after press release and is granulated to the small pieces and transported by the belt conveyer to the repulpation stage. The filtrate from the first step filtration is directed to the desalination process, to produce demineralized water, and back to the repulpation stage.

Preferably, the repulpation of the granulated cake is in demineralized weak water solution of hydrochloric acid. Other acids or salts e.g. phosphoric acid, ammonium polyphosphate, ammonium bicarbonate, magnesium sulfonate can be used. A suitable concentration of acid in the water is in the range from <NUM> to <NUM> wt. The mass ratio of water to the precipitate is between <NUM>:<NUM> to <NUM>:<NUM>. The process is conducted in a high shear dissolver with an agitation speed above <NUM> rpm. Repulpation is continued for approx. <NUM>, to have a long enough time for the contact of acid with the particles of geopolymer or geopolymer composite. After the specified time, the suspension is transferred to the second filtration step g).

The second step membrane filter press filtration is preferably coupled with a vacuum cake drying. Filled geopolymer slurry after repulpation is fed to the filter press and cloudy filtrate is recirculated to the feeding spigot. A clean filtrate is directed to a waste stream for desalination process or could be used in the dealkalization. Again, filtration is finalized when the inside press pressure reaches from <NUM> to <NUM> bar. The filtrate has a pH in the range of <NUM>-<NUM> and a conductivity below <NUM>/cm.

Next, the filter cake is washed with demineralized water, in order to remove any remaining salts. The step is finished when the ion conductivity of the filtrate is below <NUM>/cm and at a pH value between <NUM>-<NUM>, which takes a minimum of <NUM>. The membrane squeeze is necessary to decrease the water content in the filter cake below <NUM> wt. %, preferably below <NUM> wt. Then, the cake (which is characterized by a solid mass content of about <NUM>-<NUM> wt. %) is heated above <NUM>, preferably above <NUM>, and steam and vacuum drying are applied in order to achieve a water content in the filter cake below <NUM> wt. The sodium content after dealkalization, repulpation, salts washing and filtration is much below <NUM> ppm.

The salts elution process from the cake may be performed at a higher temperature, e.g. <NUM>-<NUM>, in order to accelerate cations diffusing from the geopolymer composite. The elution process can be performed at a temperature in a range of from <NUM> to <NUM>, preferably from <NUM> to <NUM>, in particular from <NUM> to <NUM>. When increasing the temperature by <NUM>, the elution process can be shortened in time by about <NUM>%, especially when the process temperature is in a range of from <NUM> to <NUM>, in particular <NUM> to <NUM>.

The geopolymer's matrix has a strong ability to be an ion exchange material. The negative charge in the amorphous structure of geopolymers is not localized and is more or less uniformly distributed in the framework. Charge-balancing cations can act as fully hydrated and mobile or as unhydrated and coordinated to oxygen atoms. The main factors determining the geopolymer preference for exchanging a cation over another one are ionic radius, hydration energy, and locations of cations. Therefore, geopolymer cationic exchange capacity allows for a wide range of chemical and physical modification, in order to change thermal and morphological properties. The geopolymer of geopolymer composite could be modified by washing with salt or acids water solutions before membrane squeezing and vacuum drying, in order to incorporate proper cations to increase self-extinguishing properties. It was surprisingly found that geopolymer composite, modified with phosphoric acid or organic, inorganic phosphoric acid esters or polyesters or their salts e.g. ammonium polyphosphates (APP), triethyl phosphate, triphenyl phosphate allows to decrease or even fully dispense with halogenated flame retardants in expanded vinyl aromatic polymer foams. The specific salt for the ion exchange, or the specific acid water solution to modify the geopolymer or geopolymer composite, could be used with a concentration in the range of <NUM> to <NUM>%, preferably <NUM> to <NUM>%, more preferably from <NUM> to <NUM>%.

The drying of precipitate at the end preferably takes place at a higher temperature, such as above <NUM> (to provide quick evaporation of water, <NUM> to <NUM> is preferred) and a vacuum, preferably vacuum means low pressure at a level of <NUM> mbar. After drying, the cake is preferably deagglomerated by the impact mill, preferably with a slow speed feeding and high speed of the rotor pin in the range of <NUM> to <NUM> rpm, preferably from <NUM> to <NUM> rpm, to have the same particle size as after the jet milling step.

Whilst a process to prepare modified geopolymer or modified geopolymer composite, as used according to the present invention, has been described in detail above, an alternative process is described in international patent application entitled "Process for the production of geopolymer or geopolymer composite" (<CIT> published as <CIT>), filed on even date herewith. <CIT> claims priority from <CIT>. According to this alternative process, modified geopolymer is prepared in a process comprising.

Step e) of this alternative process comprises.

This alternative process may comprise modification with one or more water-soluble compounds, preferably the modification is in one or more of step f) and step g), resulting in modified geopolymer or modified geopolymer composite, respectively. The water-soluble compound is again preferably selected from phosphorus compounds, nitrogen compounds, copper compounds, silver compounds, zinc compounds, tin compounds, and magnesium compounds. Preferably, the modification is with a phosphorus compound, in particular with a phosphorus compound selected from phosphoric acid and ammonium polyphosphate.

Modified geopolymer, as used according to the invention, is derived from geopolymer and is modified with one or more water-soluble compounds, selected from phosphorus compounds, nitrogen compounds, copper compounds, silver compounds, zinc compounds, tin compounds, and magnesium compounds. The modified geopolymer is preferably in the form of a modified geopolymer composite, and the modified geopolymer composite comprises one or more of the above-identified (preferably athermanous) additives.

Preferably, the modified geopolymer or modified geopolymer composite is obtainable and is in particular obtained according to the process for the production of modified geopolymer or modified geopolymer composite of the invention, as described above.

In the modified geopolymer composite according to the present invention, the amount of (preferably athermanous) additive is preferably from <NUM> to <NUM> wt. % by weight, calculated on the geopolymer composite dry mass.

The modified geopolymer composite used in accordance with the invention is preferably synthesized from metakaolin (modified geopolymeric binder based on fire clays - metaclay) and sodium or potassium polysilicate solution, preferably a sodium solution may be used, and/or carbon blacks and/or petroleum cokes and/or graphite and/or chamotte and other crystalline fire clays as cross linking precursors and/or titanium dioxide, and/or barium sulphate and/or synthetic rutile and/or ilmenite and/or perovskite and/or fumed silica and/or fly ashes and/or hydromagnesite/huntite mineral can be used as well.

The modified geopolymer composite can e.g. contain up to <NUM> % of athermanous additive from the group of carbon-based additives, such as carbon blacks and/or petroleum cokes and/or graphite and/or graphene oxide and/or nano-graphite. Various types of carbon black, petroleum coke graphite, graphene oxide and nano-graphite can be added. In addition, it is possible to incorporate graphitized carbon black together with synthetic or natural graphite or alone. The concentration of additives in the modified geopolymer composite depends on the modified geopolymer composite's viscosity, and this is related to the (athermanous) additive's particle size, and the BET surface area of the particular additive.

The modified geopolymer composite powder is preferably characterized by the following parameters:.

Kaolinite used in the preparation of the modified geopolymer (composite), as used according to the present invention, is a clay mineral composed of aluminosilicate oxides with the formula Al<NUM>O<NUM>·2SiO<NUM>·<NUM><NUM>O. It is a layered silicate mineral, with one tetrahedral sheet linked through oxygen atoms to one octahedral sheet of alumina octahedra.

Endothermic dehydration of kaolinite begins at <NUM>-<NUM>, producing disordered metakaolin, but continuous hydroxyl loss is observed up to <NUM>.

The calcination of kaolin clay at <NUM>-<NUM>, preferably <NUM>-<NUM> and more, more preferably <NUM>-<NUM>, results in metakaolin that is preferably used according to the invention.

The metakaolin used in the preparation of the modified geopolymer (composite), as used according to the invention, is preferably composed of:.

Titanium dioxide occurs in form of three common crystalline phases, namely rutile, anatase and brookite. Rutile is the most stable form, while anatase and brookite slowly convert to rutile upon heating above <NUM> and <NUM>. All three forms of titanium dioxide have six co-ordinated titanium atoms in their unit cells. Rutile and anatase structures are tetragonal. Titanium dioxide is characterized by its excellent processing properties, ease of wetting and dispersion. Moreover, it is able to absorb infrared radiation, thus in this manner was used in the synthesis of modified geopolymer composite of the invention, to decrease thermal conductivity of the expanded vinyl aromatic polymer (as measured according to ISO <NUM>).

The titanium dioxide preferably used in the preparation of the modified geopolymer (composite), as used in the present invention, has a TiO<NUM> content in the range of <NUM>-<NUM> wt. %, as measured according to standard PT-<NUM>, preferably <NUM>-<NUM> wt. %, more preferably from <NUM>-<NUM> wt. The total Al<NUM>O<NUM> and SiO<NUM> content is in the range of <NUM> to <NUM> wt. %, preferably in the range of from <NUM> to <NUM> wt. %, more preferably of from <NUM> to <NUM> wt. %, as measured according to PT-<NUM> and PT-<NUM> standards. The density is preferably <NUM> to <NUM>/dm<NUM>, as measured according to DIN ISO <NUM> standard, preferably <NUM> to <NUM>/dm<NUM>, more preferably <NUM> to <NUM>/dm<NUM>. The average particle size is in the range of <NUM> to <NUM>, preferably in the range of <NUM> to <NUM>, more preferably <NUM> to <NUM>, as measured by a Malvern Mastersizer apparatus according to the standard ISO <NUM>-<NUM>.

Ilmenite is a titanium-iron oxide mineral (FeTiO<NUM>), weakly magnetic, considered as the most important ore of titanium. Ilmenite most often contains appreciable quantities of magnesium and manganese and the full chemical formula can be expressed as (Fe, Mg, Mn, Ti)O<NUM>. Ilmenite crystallizes in the trigonal system. The crystal structure consists of an ordered derivative of the corundum structure.

The ilmenite used in the preparation of the modified geopolymer (composite), as used according to the invention, preferably has a TiO<NUM> content in the range of from <NUM> to <NUM> wt. %, preferably of from <NUM> to <NUM> wt. %, more preferably of from <NUM> to <NUM> wt. It is preferred that the total Fe content is from <NUM> to <NUM> wt. %, preferably from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. The content of SiO<NUM>, MnO, MgO, Cao, Al<NUM>O<NUM> and V<NUM>O<NUM> is in the range of from <NUM> to <NUM> wt. %, preferably in the range of from <NUM> to <NUM> wt. %, more preferably in the range of <NUM> to <NUM> wt. The density is preferably from <NUM> to <NUM>/dm<NUM>, as measured according to DIN ISO <NUM>, preferably <NUM> to <NUM>/dm<NUM>. The average particle size is in the range of from <NUM> to <NUM>, preferably in the range of from <NUM> to <NUM>, as measured by laser diffraction, using a Malvern Mastersizer apparatus according to ISO <NUM>-<NUM>.

Rutile is a mineral composed primarily of titanium dioxide (TiO<NUM>). Natural rutile may contain up to <NUM> % of iron and significant amounts of niobium and tantalum. Rutile crystallizes in the tetragonal system.

The titanium dioxide used in the preparation of the modified geopolymer (composite), as used in the present invention, preferably has a TiO<NUM> content in the range of from <NUM> to <NUM> wt. %, preferably of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. The SiO<NUM> content is in the range of <NUM> to <NUM> wt. % preferably in the range from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. The density is from <NUM> to <NUM>/dm<NUM>, as measured according to DIN ISO <NUM>, preferably <NUM> to <NUM>/dm<NUM>, more preferably <NUM> to <NUM>/dm<NUM>. The average particle size is in the range of <NUM> to <NUM>, preferably in the range of <NUM> to <NUM>, more preferable is range of <NUM> to <NUM>, measured by laser diffraction, using a Malvern Mastersizer apparatus according to the ISO <NUM>-<NUM>.

A mineral of the general formula ABX<NUM> is preferably present, A and B being cations and X being anions, wherein the mineral has perovskite crystal structure (in the following "mineral having perovskite structure", or "perovskite"). This type of additive reduces flame development by the creation of char with higher viscosity and thus reduces dripping and flaming.

The perovskite as preferably used in the preparation of the modified geopolymer (composite), as used in accordance with the invention, has the following specific properties:.

Preferably, A is selected from the group consisting of Ca, Sr, Ba, Bi, Ce, Fe, and mixtures thereof. Moreover, the A atom can be represented also by hybrid organic-inorganic groups, e.g. (CH<NUM>NH<NUM>)+.

The B atom is preferably represented by Ti, Zr, Ni, Al, Ga, In, Bi, Sc, Cr, Pb as well as ammonium groups. The X atom is preferably represented by oxygen or halide ion, or mixtures thereof.

Among the most important representatives of minerals having perovskite structure are dielectric BaTiO<NUM>, high-temperature semiconductor YBa<NUM>Cu<NUM>O<NUM>x, materials exhibiting magnetoresistance R<NUM>-xAxMnO<NUM>, where R = La<NUM>+, Pr<NUM>+ or other earth ion, A = Ca<NUM>+, Sr<NUM>+, Ba<NUM>+, Bi<NUM>+, Ce<NUM>+, and multiferroic materials.

Perovskites have large reflectance properties in the broad wavelength and a high optical constant, even in the far-infrared region. Hence, perovskites are infrared reflective materials that reflect infrared rays included in sunlight or the like and reduce the level of absorbed infrared rays.

Perovskites used in the preparation of the modified geopolymer (composite), as used according to the invention, are preferably characterized by:.

Glass water is a water soluble alkali metal silicate with a certain molar ratio of M<NUM>O:SiO<NUM> (M representing Na or K, or a mixture of Na and K), corresponding to the chemical formula M<NUM>O:2SiO<NUM>*nH<NUM>O, n being comprised between <NUM> and <NUM>. M is preferably Na.

Alternatively, M is K. Although potassium silicate is more expensive than sodium silicate, the properties of the modified geopolymers prepared with potassium silicate are much better than those obtained with sodium silicate.

The molar ratio of M<NUM>O:SiO<NUM> used in the preparation of the modified geopolymer (composite), as used in the present invention, is preferably comprised between <NUM> and <NUM>. In the following examples, the alkali metal silicate solution contains <NUM> to <NUM> wt. % by weight of SiO<NUM>, <NUM> to <NUM> wt. % of K<NUM>O or Na<NUM>O, and <NUM> to <NUM> wt. % by weight of water. The solution may be prepared in advance or may result from the dissolution of solid (powdered) alkali silicate present in the mix, with added water.

Calcium silicates with Ca/Si atomic ratio equal to or greater than <NUM>, such as wollastonite Ca(SiO<NUM>), gehlenite (2CaO·Al<NUM>O<NUM>·SiO<NUM>), akermanite (2CaO·MgO·2SiO<NUM>) are preferred. When the particles of these substances are exposed to an alkaline solution (NaOH or KOH), very rapid desorption of CaO occurs, so that the Ca/Si atomic ratio becomes less than <NUM> and is closer to <NUM>. There is an in situ production of soluble calcium disilicate Ca(H<NUM>SiO<NUM>)<NUM> that contributes to the modified geopolymeric reaction. Industrial by-products and high-temperature residues contain essentially the basic silicates gehlenite, akermanite and wollastonite, and are thus very suitable. They are found in blast furnace slag.

Under the microscope, the hardened modified geopolymer examples of cement show that the finer slag grains have disappeared. One only sees an imprint of their initial shape, in the form of a skin probably made up of akermanite, which did not react.

This process is very regular and may be complete within <NUM>. However, when the slag has a very fine grain size, such as <NUM><NUM>/kg or greater (this corresponds to a mean grain size d5O of <NUM>), the hardening of modified geopolymer composite is too fast. Now, in the prior art, the blast furnace slag used has a specific surface area in the range of <NUM> to <NUM><NUM>/kg, i.e. d5O less than <NUM>, such as in <CIT>.

In the Forss patents, the specific surface area of the slag is greater than <NUM><NUM>/kg, preferably comprised between <NUM> and <NUM><NUM>/kg. In contrast thereto, and in the preparation of the modified geopolymer (composite), as used in the present invention, preferably <NUM> to <NUM> parts by weight of blast furnace slag with a specific surface area less than <NUM><NUM>/kg or d5O between <NUM> and <NUM> are used. This results in mixtures with a pot-life ranging between <NUM> and <NUM> hours.

In general, use of calcium silicate improves the modified geopolymer properties by better dissolution of metakaolinite in the sodium activator.

The carbon black as used in the preparation of modified geopolymer composite, as used according to the invention, preferably has a BET surface, as measured according to ASTM <NUM> standard, in the range of <NUM> to <NUM><NUM>/g. The following carbon blacks within this BET surface area range can be characterized:.

It is preferred in all aspects of the invention that:.

Depending on purity, the conditions in the cooker and the subsequent calcinations, a variety of different coke types can be produced. Typical coke products are needle coke, regular coke, and sponge coke. Needle coke consists of highly structured graphene layers. Regular coke consists of irregularly oriented graphene layers. Sponge coke is a coke with highly porous structure. It is preferred to use a coke for the preparation of modified geopolymer composite having a sulphur content in the range from <NUM> to <NUM><NUM> ppm, preferably <NUM> to <NUM><NUM> ppm, as measured according to ASTM D1619, and an ash content from <NUM> to <NUM> %. In addition, preferably, the mean diameter size of coke particles should be in the range of <NUM> to <NUM>, more preferably in the range of <NUM> to <NUM>, suitably <NUM> to <NUM>.

To obtain favourable properties of modified geopolymer composite and expanded foam composite, the coke's further properties are preferably:.

The chamotte preferably used in the preparation of the modified geopolymer (composite), as used in the present invention, is preferably composed of:.

It is preferred that the water absorption of chamotte is <NUM> wt. % maximum, preferably lower than <NUM> wt. % and more preferably lower than <NUM> wt.

Moreover, the chamotte used in the preparation of the modified geopolymer (composite), as used according to the invention, preferably has a melting point of approximately <NUM>. Its thermal expansion coefficient is most preferably about <NUM>/m, and thermal conductivity (as measured according to ISO <NUM>) is about <NUM> W/(m-K) at <NUM> and about <NUM> W/(m-K) at <NUM>.

The chamotte acts as a cross-linking precursor agent.

In the present description, the term thermal silica fume designates an amorphous type of silica obtained by condensing of SiO vapours resulting from the very high temperature electrofusion of siliceous materials, generally at about <NUM>; the said alkaline silicate is preferably obtained by dissolving the said thermal silica in a concentrated solution of NaOH and/or KOH.

The thermal silica fume is preferably prepared by electrofusion of zircon sand. The obtained thermal silica fume preferably contains at most <NUM> % by weight of Al<NUM>O<NUM> and at least <NUM> % by weight of SiO<NUM>. It has a chemical formula between (13Si<NUM>O<NUM>, Al<NUM>O<NUM>) and (16Si<NUM>O<NUM>, Al<NUM>O<NUM>), representing an aluminosilicate oxide with Al in coordination (IV), with additional amorphous silica SiO<NUM>. In the following part of this specification, the aluminosilicate oxide having the characteristics of this thermal silica is written as (l5Si<NUM>O<NUM>,Al<NUM>O<NUM>), however, without excluding other thermal silica fumes with compositions containing at most <NUM> % by weight of Al<NUM>O<NUM> and at least <NUM> % by weight of SiO<NUM>.

The fumed silica acts as a cross-linking precursor agent and viscosity modifier.

Huntite (magnesium calcium carbonate with the formula Mg<NUM>Ca(CO<NUM>)<NUM>) and hydromagnesite (hydrated magnesium carbonate with the formula Mg<NUM>(CO<NUM>)<NUM>(OH)<NUM>·<NUM><NUM>O) or their combination in certain ratios are used as char promoting fire retardants. Huntite and hydromagnesite preferably have the following specific properties:.

The expandable vinyl aromatic polymer granulate preferably comprises one or more types of modified geopolymer composite (containing encapsulated or physically or chemically modified athermanous additives selected from the group of carbon black, petroleum coke, graphitized carbon black, graphite oxides, graphite and graphene, titanium oxides, barium sulphate, ilmenite, retiles, chamotte, flay ash, fumed silica, hydromagnesite/huntite mineral, perovskite mineral).

The green anthracite is a compact variety of coal which is characterized by a low content of volatile parts, high content of carbon and large heat of combustion. Anthracite is a black or dark grey material with metalloid luster. Anthracite is formed as a result of very high temperatures and very high pressure, during diagenetic and metamorphic processes.

The green anthracite used in the preparation of the modified geopolymer (composite), as used according to the present invention, preferably has a carbon content in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. The ash content is in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. The sulphur content is in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. Content of volatile parts is in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. The heat of combustion is in the range of from <NUM> to <NUM> kJ/kg, more preferably from <NUM> to <NUM> kJ/kg. The green anthracite has amorphous, disordered structure devoid of graphitic structures.

Gas calcined anthracite used is produced from raw anthracite by calcination in a vertical shaft furnace at a temperature in the range of from <NUM> to <NUM>, which results in a very homogeneous end product.

The gas calcinated anthracite has a carbon content in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. The ash content is in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. The sulphur content is in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. In the calcination process irregular carbon structures, or carbon based molecules become more ordered carbon layers and exhibit graphitic structures.

Electrically calcined anthracite is a carbonaceous material manufactured by heat treating high grade anthracite coal in an electrically "fired" calcining furnace. Anthracite is heated to temperatures of in the range of from <NUM> to <NUM>. , which results in some development of a graphitic structure in product.

Electrically calcined anthracite has a carbon content in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. The ash content is in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt.

The sulphur content is in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. Content of volatile parts is in the range of from <NUM> to <NUM> wt. %, more preferably from <NUM> to <NUM> wt. In the calcination process, irregular carbon structures, or carbon based molecules, become more ordered carbon layers and exhibit graphitic structures.

Ammonium polyphosphate is an inorganic salt of polyphosphoric acid and ammonia. The chain length (n) of this polymeric compound is both variable and branched, and can be greater than <NUM>.

In the solid state the powder of APP can have a form with an average particle size (D50) in a range of <NUM> to <NUM>.

Short and linear chain APP (n < <NUM>) are water sensitive (hydrolysis). Short and linear chain APP will begin to decompose at temperatures above <NUM>.

Long chain APP with an "n" value higher than <NUM> starts to decompose at temperatures above <NUM> to polyphosphoric acid and ammonia. Its crosslinked/branched structure shows a very low water solubility (< <NUM> / <NUM>).

APP is mainly used in polyolefin (PE, PP), thermoset resins such as epoxy resins, polyurethane, unsaturated polyester phenolic resins and others. APP is an non-toxic, environmentally friendly material and it does not generate additional quantities of smoke. The synergistic effect of modified geopolymer and APP, modified geopolymer composites and APP and geopolymer modified APP on improved self-extinguishing properties of expanded vinyl aromatic polymer foam was found in accordance with the present invention.

Preferably, the parameters, features and preferences relating to the a. modified geopolymer or b. modified geopolymer with carbon athermanous additive or c. modified geopolymer composite, and furthermore the use of vinyl aromatic copolymers with p-tert-butylstyrene as example or other vinyl aromatic comonomers, set out above in relation to the processes for the preparation of the modified geopolymer (composite) and the processes for the preparation of granulate and foam, equally apply to the expandable vinyl aromatic polymer granulate and the other aspects; the same applies for the other constituents, of the modified geopolymer composite, the granulate, the foam, and the masterbatch.

It is most preferred that the modified geopolymer or geopolymer composite, as used according to the invention, comprises a certain amount of water, preferably from <NUM> to <NUM> wt%, more preferably from <NUM> to <NUM> wt%, in particular from <NUM> to <NUM> wt%.

In a first aspect, the invention relates to the use of.

for decreasing the thermal conductivity of a foam comprising polymer (the decrease being measured according to ISO <NUM>). The polymer is a vinyl aromatic polymer.

In one embodiment, a), the modified geopolymer is used.

In a second embodiment, b), a modified geopolymer is used in combination with an additive. In this embodiment, the modified geopolymer and the additive can be added separately, to result in the filled polymer foam. Alternatively, modified geopolymer (powder) and additive (powder) are first mixed, and are then added, as the mixture of modified geopolymer and additive, to result in the filled polymer foam.

In a third embodiment, c), the modified geopolymer composite as described above is used, i.e. the material wherein the (preferably athermanous) additive is comprised within the modified geopolymer, and is preferably actually encapsulated by the geopolymer.

The claimed invention further in a second aspect relates to a process for the production of expandable vinyl aromatic polymer granulate by an extrusion or a suspension process, the process comprising the addition of.

In the second aspect, the present invention thus relates to II) a process for the production of expandable vinyl aromatic polymer in the form of granulate of so-called expandable particles (micro-pellets or beads). There are two embodiments of this process involving the addition of a) a modified geopolymer, b) a combination of a modified geopolymer with an additive, or c) the modified geopolymer composite, namely (<NUM>) an extrusion process (XEPS) and (<NUM>) a suspension polymerization process (EPS). In both types of processes, incorporation of a specific type of additive (a. above) favourably contributes to both the process conditions and the properties of the product.

In the first embodiment of this aspect, the invention relates to an extrusion process for the production of expandable vinyl aromatic polymers, preferably by twin-screw extrusion consisting of a two-step mixing of the additive and flame retardant in two twin-screw extruders. Mixing takes place in a side twin screw extruder to which the additive (modified geopolymer, or combination of modified geopolymer with additive or mixture of additives, or modified geopolymer composite) is added through the two side feeders, in order to better degas the melt from excess of water and air. In this way, a filler masterbatch is created "in situ" and the filled melt is then (preferably directly, i.e. as melt) transferred to the main 32D twin-screw extruder.

The main extruder is filled with general purpose polystyrene (the same as the one dosed to the side twin screw extruder), polymeric brominated flame retardant, synergist of flame retardant (a type of initiator or peroxide) and nucleating agent (a type of polyethylene wax, or one with <NUM> % crystallinity obtained in a Fischer-Tropsch production process). Then, the melt is impregnated with blowing agent (propellant, typically pentanes, or a suitable mixture). The melt containing all additives is then cooled in a single screw extruder. The melt is then downstream processed in a pressurized underwater pelletization process, to obtain vinyl aromatic polymer granulate. The granulate is finally coated with a mixture of zinc (or magnesium) stearate, glycerine monostearate and glycerine tristearate. If a brominated flame retardant is used, the modified geopolymer or modified geopolymer composite preferably has a low alkali content.

According to the first embodiment of aspect (II), expandable vinyl aromatic polymer granulate is preferably prepared in an extrusion process as shown in detail in <CIT>.

The use of a brominated flame retardant can in accordance with the invention be reduced or even be dispensed with, for instance if the modified geopolymer or modified geopolymer composite incorporates polyphosphate flame retardant. Especially if no brominated flame retardant is used, the modified geopolymer or modified geopolymer composite of the present invention need not have a low alkali content.

In the second embodiment of the second aspect of the invention, expandable vinyl aromatic polymer is prepared in a suspension polymerization process.

In the first step of a preferred suspension process, radically initiated copolymerization preferably takes place in the presence of powder of a. modified geopolymer, or b. combination of modified geopolymer with additive, or c. modified geopolymer composite, each preferably hydrophobized on the surface by the coupling agents, in particularly by vinyl silanes. In the next step, mixing of prepolymer as obtained in first step with vinyl aromatic polymer takes place, preferably in a twin-screw co-rotating extruder. Underwater pelletization gives a masterbatch in the form of granulate. Then, this masterbatch is preferably, dissolved in styrene, together with flame retardant and nucleating agent. Water is then added, followed by peroxide and surfactants. The polymerization is continued at a temperature in a range of from <NUM> to <NUM>. Next, the resultant polymer is centrifuged to remove the water from the polymer particles (granulate), the particles are dried and are finally coated with a mixture of magnesium (or zinc) stearate and/or mono- and/or di- and/or tristearate of glycerine.

The suspension process preferably comprises the steps as described in more detail in <CIT>.

III) Composition comprising polymer and i) modified geopolymer, ii) the combination of a modified geopolymer with an additive, or iii) a modified geopolymer composite.

In a third aspect, the claimed invention relates to a composition comprising one or more polymers, the composition further comprising.

The polymer that is used together with the modified geopolymer or the modified geopolymer composite is vinyl aromatic polymer, and most preferably the vinyl aromatic polymer is polystyrene.

The composition can be in the form of expandable vinyl aromatic polymer granulate, in the form of expanded vinyl polymer foam, or in the form of a masterbatch.

Further preferred is expandable vinyl aromatic polymer granulate, and an expanded foam products made thereof, which comprises vinyl aromatic polymer prepared from styrene monomer with optional incorporation of one or more vinyl comonomers, and.

Expandable vinyl aromatic polymer granulate may be expanded to form foam with a uniform structure independently from the concentration of modified geopolymer or modified geopolymer composite in the foam. A uniform structure is characterized by the cell size distribution, as measured by a statistical analysis of the picture prepared by an optical microscopy measurement.

Preferably, and according to the third aspect, the claimed invention relates to the expandable vinyl aromatic polymer granulate (particles) as obtainable according to the second aspect, preferably as obtainable in an extrusion or a suspension processes.

The expandable vinyl aromatic polymer granulate comprises polymer, one or more propellants and additive which is a. modified geopolymer, or b. a combination of a modified geopolymer with an additive, but is preferably c. the modified geopolymer composite as prepared from modified geopolymer and suitable additive such as those from the group of carbon based athermanous additives, with optional addition of modified geopolymeric binders and minerals. The binders and/or minerals and/or carbon-based athermanous additives can be used alone in the b. combination of modified geopolymer or be used separately according to the desired properties of modified geopolymer composite and final (foamed) product.

Additionally, the granulate or foam may contain: brominated flame retardant, preferably an environmentally friendly polymeric brominated flame retardant (Emerald <NUM> from Chemtura, FR-122P from ICL or GREENCREST from Albemarle); synergist from the group of initiators or peroxides with relatively high temperature of decomposition; nucleating agent with high degree or crystallinity, preferably polyethylene oligomers from the group of Polywax (Baker Hughes) or Fischer Tropsch waxes from Evonik for example; blowing agent from the group of low boiling hydrocarbons, such as pentane or its suitable mixtures with isopentane.

The vinyl aromatic polymer used in all aspects of the invention is in particular polystyrene or a vinyl aromatic styrene copolymer. In the copolymer, a part of styrene monomer is substituted with unsaturated comonomers, the reactivity of which is close to styrene monomer's reactivity, such as p-methyl styrene and its dimers, vinyl toluene, t-butyl styrene or divinylbenzene. For the extrusion process and suspension process, typically used vinyl aromatic polymers have a different number average molecular weight.

In the extrusion process, it is preferred to use a general purpose type of polystyrene (or a copolymer with unsaturated styrene derivative) with a number average molecular weight (Mn) of from <NUM> to <NUM>/mol, preferably of from <NUM> to <NUM>/mol, more preferably of from <NUM> to <NUM>/mol, and a suitable polydispersity of Mw/Mn in a range of from <NUM> to <NUM>, preferably of from <NUM> to <NUM>, more preferably of from <NUM> to <NUM>, and Mz/Mw in the range of from <NUM> to <NUM>.

The vinyl aromatic polymer as produced in the suspension process preferably has a number average molecular weight (Mn) from <NUM> to <NUM>/mol, preferably of from <NUM> to <NUM>/mol, more preferably of from <NUM> to <NUM>/mol, and a suitable polydispersity Mw/Mz in a range of from <NUM> to <NUM>, preferably from <NUM> to <NUM>, more preferably from <NUM> to <NUM>, and Mz/Mw in the range of from <NUM> to <NUM>.

Typically, a flame retardant is used according to all aspects of the invention, to make expanded vinyl aromatic polymers which are self-extinguishing. The flame retardant is usually a combination of two types of compounds, namely a brominated aliphatic, cycloaliphatic, aromatic or polymeric compound containing at least <NUM> wt. % of bromine, and a second compound (so called synergistic compound) which can be bicumyl (i.e. <NUM>,<NUM>-dimethyl-<NUM>,<NUM>-diphenylbutane) and/or its polymeric form, or <NUM>-hydroperoxy-<NUM>-methylpropane.

Alternatively, a phosphorus flame retardant or a nitrogen flame retardant or a phosphorus/nitrogen flame retardant can be used, as set out above.

Optionally, the flame retardant can be stabilized by addition of thermo-oxidative stabilizers, especially standard components (e.g. Irganox <NUM> in synergistic mixture with Irgafos <NUM>), in which the components are used in a ratio of <NUM>/<NUM>, preferably <NUM>/<NUM>. The bromic acid scavenger used can be an epoxy resin, e.g. a solid multifunctional epichlorohydrin/cresol novolak epoxy resin, for example Epon <NUM> with an epoxy equivalent weight of <NUM> to <NUM>/eq. The resin is typically used in a ratio of <NUM>/<NUM> with Irganox <NUM> and Irgafos <NUM>.

Other acid scavengers that can be used are special grades of hydrotalcite such as DHT-4A from Kisuma Chemicals and hydromagnesite/huntite mineral, a hydrated magnesium carbonate mixed with platy magnesium calcium carbonate (such as UltraCarb <NUM> from Minelco). Additionally, hydromagnesite/huntite can act as halogen free flame retardant and smoke suppressant and can thus in combination with brominated flame retardant strengthen the self-extinguishing effect. A beneficial influence of this mineral in the reduction of thermal conductivity was also noticed.

A process for the production of expanded vinyl aromatic polymer foam preferably comprises the following steps:.

The composition according to the third aspect can be in the form of expanded vinyl polymer foam, the foam having.

The vinyl polymer is vinyl aromatic polymer, and the foam is preferably obtainable by expansion of the granulate.

In a preferred embodiment, the composition is in the form of a masterbatch comprising vinyl polymer, and.

Preferably, the amount as per a. is in a range of from <NUM> to <NUM> wt. %, based on the weight of the masterbatch, more preferably the amount is in a range of from <NUM> to <NUM> wt. %, in particular the amount is in a range of from <NUM> to <NUM> wt.

The vinyl polymer of the masterbatch is a vinyl aromatic polymer, more preferably the vinyl aromatic polymer has a melt index in a range of from <NUM> to <NUM>/<NUM>, as measured according to ISO <NUM>, in particular the vinyl aromatic polymer is a homopolymer or copolymer with p-tert butyl styrene or alpha-methyl styrene.

In a preferred embodiment, the masterbatch further comprises one or more silanes. Preferably, the amount of silane is in a range of from <NUM> to <NUM> wt. %, based on the respective weight of a. in the masterbatch.

The foam (made of expanded vinyl aromatic polymer with addition of a. modified geopolymer, or b. combination of modified geopolymer with additive, or c. modified geopolymer composite) has a density of from <NUM> to <NUM>/m<NUM>, and a thermal conductivity (as measured according to ISO <NUM>) of from <NUM> to <NUM> mW/K·m. Specifically, the foam should have thermal conductivity for low densities in the range of from <NUM> to <NUM> mW/m·K at densities of from <NUM> to <NUM>/m<NUM>. For higher densities, thermal conductivity is preferably in the range of from <NUM> to <NUM> mW/mK, at densities of from <NUM> to <NUM>/m<NUM>.

In all aspects of the invention, when c. modified geopolymer composite is present, this does not exclude the presence of additive that is not contained within the modified geopolymer composite.

The materials according to the invention (the polymer composition, the granulate, the foam and the masterbatch) may, in addition to.

contain further additives, as is set out above.

It is noted that, unlike the properties of the starting materials, the properties of additives as contained in the granulate or foam are notoriously difficult to determine. It is often considered more appropriate to characterize the additives in granulate and foam with reference to the properties of the additives as initially used.

It is further noted that, whenever reference is made in the description to an "additive", this is in all embodiments and aspects of the invention preferably a reference to an "athermanous additive", as athermanous additives are most preferred additives.

The advantages of the present invention become apparent from the following examples. Unless indicated otherwise, all percentages are given by weight.

Moreover, whenever reference is made in the description to an amount of any additive "by weight of polymer", this refers to the amount of the additive by weight of polymer component inclusive of (solid and, if any, liquid) additives, but exclusive of propellant.

The following examples show a process for geopolymer or geopolymer composite preparation, including modification options. Further, these examples show the influence of this modification for the vinyl aromatic polymer foam's properties.

The following geopolymers were prepared with below described process (Tables <NUM> and <NUM>).

The components: <NUM> of a powder mixture comprising <NUM> of metakaolinite from České Lupkové Závody, a. , Czech Republic and <NUM> of furnace slag from ironworks Katowice, Poland and <NUM> of sodium water glass with a molar module of <NUM> from Rudniki, Poland were charged into a high speed screw conical mixer having a volume of <NUM><NUM> and mixed over <NUM>. with a speed of <NUM> rpm, to obtain a thixotropic sol-gel. Then, the carbon additive, namely petroleum coke (Ranco <NUM> from Richard Anton KG having a mean diameter particle size of <NUM>, a BET surface area of <NUM><NUM>/g and total surface area of pores <NUM><NUM>/g, <NUM>-<NUM> pores size content of <NUM>%and a sulphur content of <NUM> ppm) was added in an amount of <NUM>, and <NUM> of water was added subsequently to the gel and mixed during the next <NUM>, also with a high speed of <NUM> rpm. After that, the viscous, homogenous gel was discharged from the mixer directly do an open mould made of polished stainless steel (total amount of <NUM>). The mould was then closed and left for <NUM> to perform geopolymerization. After <NUM> hours, the mould was opened and transported to the drier to perform drying process for <NUM> at a temperature of <NUM>, and <NUM> at a temperature of <NUM>. Under these conditions, the geopolymer composite was dried over <NUM>, and approx. % of water excess was evaporated from the material. Still approx. <NUM>% of water remain in the material.

The dried geopolymer composite block was then placed into a crusher to obtain the granulate. The granulate with an average particles size of <NUM> was jet milled with the use of hot air as milling medium, to obtain free flowing powder.

The fine powder, containing of about <NUM> wt. % of water (amount of approx. <NUM>), was then placed in a <NUM><NUM> in heated dissolver (reactor), equipped with a high speed agitator and ribbon stirrer turning closely to the dissolver walls. Immediately thereafter, <NUM> of filtrated process water were charged into the dissolver and mixing was started simultaneously. An amount of <NUM> of concentrated aqueous hydrochloric acid (<NUM> %) was then added to reactor over <NUM> and dealkalization was performed. The starting pH, as measured before acid addition, was <NUM>, after <NUM>. of mixing and dealkalization the final pH was <NUM>. The water (filtrate) with a conductivity of about <NUM>,<NUM>/cm was filtrated from the powder of geopolymer composite and the precipitate was obtained, containing approx. % of water. Then, a portion of process water was used to wash remaining sodium chloride and other chlorides from the precipitate. Washing was continued for <NUM>, to obtain a filtrate having a conductivity below <NUM>/cm. After that, a membrane squeeze of about <NUM> bar was applied, to increase the solids content to <NUM> wt. The precipitate was removed from the press, granulated and loaded to a repulpation dissolver with the same mixing system as for the dealkalization reactor. Further salts elution in a diluted solution of hydrochloric acid (<NUM>%) and deionized water was performed. Following repulpation, the slurry was filtrated and washed for about <NUM>, to obtain a filtrate having a conductivity below <NUM>/cm.

Optionally, and to further improve self-extinguishing of vinyl aromatic foams with the use of geopolymeric composite, <NUM> wt. % of a solution of phosphoric acid (preferably <NUM>% concentrated) in demineralized water was pumped through the filter press, to modify the surface of geopolymer or geopolymer composite. A precipitate with a water content of about <NUM> wt. % was then finally vacuum dried over <NUM> at a temperature of <NUM> and a pressure level of about <NUM> mbar. The dry precipitate, containing of about <NUM>% of water and <NUM> wt. % of phosphoric acid in its structure, was then granulated and deagglomerated in an impact mill, to result in a fine powder with a D50 of about <NUM> as presented on <FIG>. The <NUM> wt. % content of phosphoric acid was analysed in the geopolymeric additive. The content of analysed sodium was <NUM> ppm.

To improve the adhesion of petroleum coke or other carbon based filler to the geopolymer, <NUM> wt. % of aminopropyltriethoxysilane or phenyltriethoxysilane was added to the mixture of metakaolinite and furnace slug (<NUM> wt. % of silane per amount of mixture) before addition of sodium glass water, and mixed for <NUM>. in a conical mixer. It is possible that special equipment for silanization of powders can be used, for example a twin-cone blender or a vacuum tumble dryer, or it could be performed earlier in the solvent conditions, in toluene for example. Alternatively, functionalization with silane of geopolymer can be performed during mixing of the gel.

To further improve adhesion and thus dispersion of the geopolymer composite powder in the expandable vinyl aromatic polymer as obtained by the extrusion process, one can perform silanization of the final powder. Phenyltriethoxysilane can be used for this purpose, in a concentration of <NUM> wt. % calculated per geopolymer composite powder amount.

Finally, to further reduce the thermal conductivity coefficient (lambda) and to thus improve the insulating properties of vinyl aromatic polymer foams according to the present invention, the geopolymeric composite can be modified with <NUM> wt. % solution of copper (II) chloride via ion exchange. This could be done in the repulpation stage or after salts washing by demineralized water in the filter press. In that case, the CuCl<NUM> solution is pumped through the press with a pressure of about <NUM> bar in the closed loop, preferably ten times the mass of the solution must flow through the press. After this, vacuum drying is performed as described already. Obtained geopolymer powder usually contain approx. % of copper in the structure.

At the end the final powder with an average particles size (D50) of <NUM>,<NUM>, containing D90 = <NUM>, D99 = <NUM> (<FIG>), BET <NUM><NUM>/g and total surface area of pores <NUM><NUM>/g, <NUM>-<NUM> pores size content of <NUM>%. The pore size of about <NUM> to <NUM> was increased of about <NUM>%. The table below shows the difference is pore content of different size for obtained geopolymer composite particle and unmodified petroleum coke (Ranco <NUM>) particle (before modification via geopolymer), which examples that homogenous new type of particle was obtained. The mesoporosity was significantly increased, as shown below (Table <NUM>):.

From all performed analyses of the quality of obtained geopolymers or geopolymer composites the sodium content is presented as the most important, from an improved process point of view. Later it could be seen how sodium content and phosphorus compound content influence the foam self-extinguishing properties and to which content in the foam brominated flame retardant could be reduced.

A crucible with <NUM> dried sample is placed in the oven for <NUM> at <NUM> for burning. The ash after burning is cooled down, in the next step ca. <NUM> deionized water with <NUM> HCl (<NUM>-<NUM>%) is added to the crucible with sample, and the content is heated using a laboratory hotplate at <NUM> for <NUM>. The sample is cooled down and transferred through the filter (cleaned beforehand for a minimum of <NUM> times using deionized water) into the <NUM> flask, in the next step <NUM> <NUM> nitric acid with <NUM> spectral buffer of cesium chloride (<NUM>% Cs) is added. Simultaneously with the sample for analysis one control (blank) sample is prepared using the same procedure and the same reagents.

The sample solution as prepared applying the procedure described above is measured by Atomic Absorption Spectrometer, using a device AA iCE <NUM> GFS35Z, and following parameters: working mode: absorption, wave length: <NUM>, gap: <NUM>,.

The presented analytical procedure is based on the standard defining Na analysis PN-ISO <NUM>-<NUM>:<NUM>+Ap1:<NUM>, sample preparation for measurement is based on internal procedure standard <NUM>/A issue <NUM> dated <NUM>.

The content of H<NUM>PO<NUM> and ammonium polyphosphate and the metal content were concluded from x-ray spectroscopy (XRF), by measuring the content of phosphorus or metal, calculated as content of P<NUM>O<NUM> or metal oxide. XRF was performed with the use of a vessel for powders and oils analysis on the Prolen foil with thickness of <NUM>. A WD-XRF model S8 Tiger apparatus from Bruker was used to perform analysis.

The specific surface area was determined using a Gemini <NUM> (Micromeritics) device. The measurement minimum of the Gemini <NUM> apparatus for specific surface was from <NUM><NUM>/g, the total surface range was from <NUM> to <NUM><NUM> , and the pore size starting from <NUM>·<NUM>-<NUM> cm<NUM>/g. Analysis was performed in a range P/P<NUM> from <NUM> to <NUM>. Degasification of sample was made in an inert gas atmosphere of nitrogen (with flow of <NUM><NUM>/min. Later, the sample was dried over <NUM> at a temperature of <NUM>. Nitrogen was used as measurement gas.

The pore size of the samples was measured using a Autopore IV <NUM> device according to an internal standard. Mercury contact angle is <NUM>°. Before the measurement, each sample was conditioned for <NUM> at <NUM>.

A mixture of vinyl aromatic polymer in the form of granules, containing <NUM> wt. % of Emerald <NUM>, <NUM> wt. % of bicumyl and <NUM> wt. % of nucleating agent (Polywax <NUM>), was dosed to the main hopper of the main 32D/<NUM> twin-screw co-rotating extruder. The melt temperature in the main extruder was <NUM>.

The geopolymer composite powder as prepared in EXAMPLE <NUM> was dosed in a concentration of <NUM> wt. % (per foam composition) to the side arm (54D/<NUM>) twin-screw co-rotating extruder via two side feeders, and the vinyl aromatic polymer (in the form of granules) was dosed to the main hopper of this extruder. The melt, containing <NUM> wt. % of concentrated geopolymer additive, was transported to the main extruder. The melt temperature inside the extruder was <NUM>.

The blowing agent (n-pentane/isopentane mixture <NUM>/<NUM> %) was injected to the main 32D/<NUM> extruder, downstream from the injection of the melt from the side twin-screw extruder. The concentration of blowing agent was <NUM> wt. %, calculated on total mass of product.

The melt of vinyl aromatic polymer containing Emerald <NUM> flame retardant, bicumyl, nucleating agent, geopolymer composite and blowing agent was transported to the 30D/<NUM> cooling extruder and pumped through a <NUM> length static mixer, melt pump, screen changer, diverter valve, and extruded through the die head with <NUM> diameter holes, and underwater pelletized by the rotating knifes. Downstream, the rounded product, a granulate with a particle size distribution of <NUM> % of the fraction <NUM>-<NUM> was centrifuged to remove the water, and was finally coated by the suitable mixture of magnesium stearate with glycerine monostearate and tristearate. The melt temperature in the cooling extruder was <NUM>.

The coated beads were expanded, to measure the final general properties of expanded foam composite:.

The expandable granulate with a particle size distribution <NUM> to <NUM> was in the pre-expander vessel treated for <NUM> sec. with steam having a pressure of <NUM> kPa, and was then dried in a connected fluid bed drier. The obtained beads' density was <NUM>/m<NUM>. Then the expanded beads were conditioned in a silo for <NUM> and introduced to the block mould with dimensions of <NUM> x <NUM> x <NUM>. Steam having a pressure of <NUM> kPa was used to weld the beads, and to obtain moulded blocks having a density of <NUM>/m<NUM>. The mould cooling time in this case was <NUM> sec. The ready block was cut into plates and then specimens after <NUM> days of conditioning at room temperature.

Examples <NUM> to <NUM> are comparative, and Examples <NUM> to <NUM> are according to the claimed invention.

This example shows the use of geopolymer composite as prepared according to the process of <CIT>, without use of a repulpation step and a second step of filtration, to show the importance of the improvement of the process for geopolymer or geopolymer composite production (see Example <NUM> below, Table <NUM>). In this example, foam containing <NUM> wt% of Emerald <NUM> was produced. The self-extinguishing properties as presented in Table <NUM> were obtained.

This example presents the properties of exactly the same material as in Example <NUM>, but a foam with addition of <NUM> wt. % of Emerald <NUM> was obtained. The self-extinguishing properties were obtained as presented in Table <NUM>. With the reduction of the concentration of the flame retardant Emerald <NUM>, the self-extinguishing is worse than in Example <NUM>.

This example present properties of exactly the same material as in Example <NUM>, but a foam with addition of <NUM> wt. % of Emerald <NUM> was obtained. The self-extinguishing properties were obtained as presented in Table <NUM>. With the reduction of Emerald <NUM> concentration, the self-extinguishing is even worse than in Example <NUM>.

This example presents the advantage when the geopolymer composite <NUM> with a reduced content of sodium was used to prepare the EPS foam. In this case, the same concentration of Emerald <NUM> was used as in Example <NUM> (<NUM> wt. The self-extinguishing properties were obtained as presented in Table <NUM>. With the reduction of the sodium concentration, the self-extinguishing at the same content of Emerald <NUM> was improved.

This example is comparable to Example <NUM>, but in this case the Emerald <NUM> concentration was reduced to <NUM> wt. The self-extinguishing properties were obtained as presented in Table <NUM>. With the reduction of Emerald <NUM> concentration and without changing sodium concentration, the self-extinguishing is worse.

This example is comparable with Example <NUM>. The same content of Emerald <NUM> was used (<NUM> wt%), but the sodium content was reduced by increasing the concentration of hydrochloric acid solution in the repulpation process. The self-extinguishing properties were obtained as presented in Table <NUM>. With the reduction of sodium concentration, the self-extinguishing at the same content of Emerald <NUM> was improved.

This example is comparable with Example <NUM>, with the exception that half of the coke Ranco <NUM> was replaced by a <NUM>/<NUM> mixture of gas calcined anthracite and metallurgical coke. The same foam properties of foam with slightly deteriorated lambda were obtained.

This example is comparable to Example <NUM>. Butadiene-styrene was added to the geopolymer composite. The geopolymer was firstly functionalized with use of acrylic-based silane, to incorporate double bonds into the aluminosilicate structure. These double bonds later reacted cross-linked with latex unsaturated bonds, to form a hybrid material. Such modified geopolymer composite powder has a better cohesion to the EPS polymer, thus mechanical properties could be improved, as well as "lambda", because less agglomeration during extrusion process took place. The properties of foam were improved despite of a higher content of geopolymer composite due to the need to keep the same concentration level of geopolymer phase in the foam.

In this example, the geopolymer composite was modified with use of phosphoric acid, as applied via washing of the precipitate cake in the filter press. The improvement is shown by reducing the amount of Emerald <NUM> to <NUM> wt. % in the EPS foam. The self-extinguishing properties were obtained as presented in Table <NUM>. With modification by phosphoric acid (<NUM> wt. %), the self-extinguishing of EPS foam at the lowered content of Emerald <NUM> was maintained on a satisfactory level.

This example is comparable with Example <NUM>. The content of phosphoric acid in the powder was increased up to <NUM> wt. The same content of Emerald <NUM> was kept and the self-extinguishing of foam EPS was improved. The self-extinguishing properties were obtained as presented in Table <NUM>. This was figured out for example with geopolymeric additive modified by phosphoric acid that there is a different behaviour of samples during the test relying on better heat absorption by the foam, thus more intensive melting of samples was observed, however, no ignition or flaming was observed especially for sample <NUM>.

This example is comparable with Example <NUM>, but instead of phosphoric acid, the water solution of ammonium polyphosphate (Exolit AP <NUM>) was used for the geopolymer composite modification. To show the self-extinguishing improvement, the Emerald <NUM> content was reduced to <NUM> wt. The self-extinguishing properties as obtained are presented in Table <NUM>.

This example is comparable with Example <NUM>, but the modification with the use of ammonium polyphosphate (Exolit AP <NUM>) solution was performed in a repulpation step, where APP was dosed instead of hydrochloric acid. The same properties of EPS foam as for Example <NUM> were obtained.

This example shows how modification of geopolymer composite via ion exchange step could be modified. In this example, copper chloride was used and an improvement of "lambda" reduction is shown.

Claim 1:
Use of
a. a modified geopolymer derived from geopolymer and modified with one or more compounds selected from phosphorus compounds, nitrogen compounds, copper compounds, silver compounds, zinc compounds, tin compounds, and magnesium compounds;
b. a combination of i) a modified geopolymer derived from geopolymer and modified with one or more compounds selected from phosphorus compounds, nitrogen compounds, copper compounds, silver compounds, zinc compounds, tin compounds, and magnesium compounds, with ii) an additive; or
c. a modified geopolymer composite derived from geopolymer, modified with one or more compounds selected from phosphorus compounds, nitrogen compounds, copper compounds, silver compounds, zinc compounds, tin compounds, and magnesium compounds, the modified geopolymer composite further comprising additive,
for decreasing the thermal conductivity of a foam comprising polymer (the decrease being measured according to ISO <NUM>),
wherein the polymer is a vinyl aromatic polymer.