WO2008113609A2

WO2008113609A2 - Geopolymer composition, coating obtainable therefrom and methods

Info

Publication number: WO2008113609A2
Application number: PCT/EP2008/002342
Authority: WO
Inventors: Yuan Jinghua
Original assignee: Xuhong, Turella-Yuan
Priority date: 2007-03-22
Filing date: 2008-03-25
Publication date: 2008-09-25
Also published as: WO2008113609A3; CN101045832A

Abstract

The present invention relates to a composition comprising: (i) 15 to 70 wt.-% a film forming geopolymer precursor; and (ii) 85 to 30 wt.-% geopolymer-containing filler particles; wherein the wt.-% of (i) and (ii) are based on the total weight of the film forming geopolymer precursor and the geopolymer-containing filler particles. This composition is suitable for preparing coatings.

Description

New PCT patent application Our ref.: P1598 PCT

Geopolymer composition, coating obtainable therefrom and methods

FIELD OF THE INVENTION

The present invention relates to a geopolymer composition, a method for forming the composition, and a coating obtainable from the composition. Furthermore, the use of the composition and a method of making a coating are disclosed.

BACKGROUND OF THE INVENTION

The coating industry is a material-intensive manufacturing industry. Materials which might be harmful to both humans and the environment are used in the manufacturing of most organic coatings. Harmful and hazardous materials used in the production process or in and after the preparation of the organic coating might volatilize into the atmosphere. The adverse impact on the environment resulting from the aforementioned materials has attracted global attention. In addition, the manufacture of organic coatings also consumes large quantities of natural resources, especially petroleum resources. The study of inorganic coatings has therefore been focused on. Inorganic coatings have many advantages. They are environmentally friendly, functional and have both technical and economic advantages. For example, sodium, potassium as well as lithium silicate resin cements, silica sols, phosphates and polysiloxanes are inorganic coating components.

However, there are some flaws and shortcomings in the properties of inorganic coatings. The main base materials of inorganic coatings for the binder materials are sodium, potassium as well as lithium silicate resin, silica sol, and polysiloxane phosphate. Due to the brittleness and poor flexibility of the film (gel coat) formed, it may easily crack. Besides, the adhesion to organic substrates and to polymeric substrates is poor, so the application of it is limited in scope. Decorative effects of inorganic coatings are not as good as of organic coatings owing to their bad levelling. There is less variety of inorganic coatings at the moment. Due to the above mentioned problems, inorganic coatings may not be able to meet the market demand in many ways.

The concept of geopolymers was brought up by Joseph Davidovits in the 1970s. The gist of this concept is an aluminum silicate inorganic polymer formed by geochemistry. The geopolymer has a network-like structure of amorphous inorganic polymer which has excellent adhesive properties, and especially shows a high bond strength in an early stage. Geopolymers also have the properties of good acid resistance, alkali resistance, seawater and high temperature resistance. Due to their high degree of compactness, ability of impermeability and antifreeze properties and especially excellent interface coalescence, geopolymers can be combined with different base materials to form a solid surface which can maintain long-term volume stability.

A wide range of products can be created by using geopolymers. Coatings are one of them. Coatings are decorative, protective and functional products. The majority thereof should have a desirable color. Therefore white metakaolin as an aluminum silicate polymer can be provided for a white coating matrix, which also helps preparing bright colors. Many publications describe inorganic coatings, but reports relating to geopolymer coatings are few and far between. The Chinese "New Architectural Materials" in the magazine 2004.5 "Experimentation & Study on Geopolymer Coating" describes a test. Metakaolin in a weight ratio of 20 %, an alkaline agent and a preparation of industrial grade sodium silicate and a certain concentration of liquid sodium silicate in a weight ratio of 45 %, and fillers (CaCO₃ with the fineness of 600; wollastonite powder with the fineness of 600) in a weight ratio of 12 % were used as raw materials. After weighing and mixing evenly, the mixture was left for 1 hour. Then it was brushed onto a prepared floor (asbestos-cement board). After 5 hours it was brushed once again (total thickness about 0.5mm). After 28 days a performance function test was performed.

The geopolymer coating reported in the article "Experimentation & Study on Geopolymer Coating" is a two-component coating. Before use the liquid component (alkaline agent) and the solid components (metakaolin, filler) must be mixed with each other, stirred well and then left for 1 hour.

Compared with single-component coatings, the costs of packaging, transportation and storage of two-component geopolymer coatings are higher. Also, two-component geopolymer coatings are more inconvenient to use at the construction site. Furthermore, they are prone to error which will affect the quality of the coatings.

The liquid sodium silicate (water glass) of the alkaline agent of the two-component geopolymer coating is polysilicic acid mixed with a solution of sodium hydroxide. During storage (freshly produced liquid component over 15 min) polysilicic acid polymerization result in disproportionation. The number of gel particles of the liquid sodium silicate (water glass) increases to promote gel processes which can result in non-reversible aging. It is quite difficult to predict the influences such as storage conditions and duration between the time the two components leave the production line before they enter the market and are ultimately used to form a geopolymer coating. The viscosity of the liquid sodium silicate will continuously drop with the changes of time and environment. The quality variables during construction will have a direct impact on the expected performance of the geopolymer coating until product failure. J. Davidovits has filed a number of patent applications relating to geopolymers. One patent, US-A-5, 798,307, summarizes some of his earlier applications. The patent US-A-5,798,307 itself relates to a specific alkaline alumino-silicate geopolymeric matrix for composite materials with fiber reinforcement and a method for obtaining the same.

In US-A-5,228,913 certain compositions which set in the presence of water and their use in forming molded articles are disclosed.

US-A-5,244,726 describes a specific self-hardened, temperature-resistant, foamed composite. An alkali metal silicate-based matrix devoid of chemical water has dispersed therein inorganic particulates, organic particulates or a mixture thereof. It is produced at ambient temperature by activating the silicates of an aqueous, air-entrained gel containing matrix-forming silicate, particulates, fly ash, surfactant and a pH-lowering and buffering agent.

An inorganic binder composition which has a first constituent, which is a poly(sialate) or a poly(sialate-siloxo), which is admixed with a second constituent, which has one or more of: fly ash F, fly ash C, fumed silica, Al₂O₃, pozzolan, ground slag, nephelene cyanite, anhydrous aluminum silicate, hydrous aluminum silicate, hydrous sodium hydroxide, silicic acid, potassium salt, and sodium salt is described in US-A-5, 820,668.

In US-A-5,851,677 a specific coating composition is described which comprises a geopolymer.

US-A-6,869,473 discloses a cementicious material including stainless steel slag and geopolymer that can be added to conventional cement compositions, such as Portland cement, as a partial or total replacement for conventional cement materials. The stainless steel slag may comprise silicates and/or oxides of calcium, silicon, magnesium, iron, aluminum, manganese, titanium, sulfur, chromium and/or nickel. The geopolymer may comprise aluminum silicate and/or magnesium silicate. A fire resistant laminate for application to a core structure to form a sandwich panel having fire resistant face sheets is described in US-A-6,992,027. The laminate includes a fire protection in which at least one layer of fibers is embedded within a cured inorganic polymer matrix. The laminate further includes an adhesive layer for bonding to the core structure.

With the traditional mode of preparing a geopolymer coating from a mix-dispersion-package it is only possible to cement uniformly distributed pigments and fillers together and form a thin layer of coating on the substrate. It is proved that geopolymer binder, pigments, and fillers are unable to react, they are unable to form a transition layer. Furthermore, the solidification of the geopolymer coating is performed under ambient conditions. The ambient temperature, humidity and other factors might not be the ideal conditions of the solidification of the geopolymer coating. If the mechanical properties of the geopolymers are not given full play, the coating might have defects such as exposed filler, cracking and peeling of the surface, so that the flexibility and levelling of the geopolymer coating hardly meet the performance norm of organic coatings.

It is therefore an object of the present application to provide a composition which can provide a geopolymer coating that has improved mechanical properties.

SUMMARY OF THE INVENTION

The present invention relates to a composition comprising:

(i) 15 to 70 wt.-% film forming geopolymer precursor; and

(ii) 85 to 30 wt.-% geopolymer-containing filler particles; wherein the wt.-% of (i) and (ii) are based on the total weight of the film forming geopolymer precursor and the geopolymer-containing filler particles.

In a further embodiment the invention refers to a method of forming the above mentioned composition, wherein the method comprises the steps of:

(a) providing geopolymer particles; and

(b) mixing the geopolymer particles with the film forming geopolymer precursor. Yet another embodiment of the invention is a coating obtainable from the above mentioned composition.

Furthermore, the invention refers to the use of the above mentioned composition for the preparation of a coating.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a composition comprising:

(i) 15 to 70 wt.-% film forming geopolymer precursor; and

The compositions of the present invention are advantageous because they do not rely on petrochemical products. Therefore, they do not require any volatile organic solvents or emit any volatile organic compounds. Rather they can be formulated only using water as a solvent. In addition they do not have aging problems, are incombustible, anti-corrosive, possess high strength, and are environmental friendly. Furthermore, the geopolymer-containing filler particles have a good fiowability. The binding properties and capability when mixed with the film forming geopolymer precursor are superior since they are both geopolymer-based materials.

The amount of film forming geopolymer precursor in the composition is 15 to 70 wt.-%. If it is below 15 wt.-%, the cementing power of the composition tends to be reduced, the application properties tend to be reduced and the surface might be rough. Furthermore, the resultant coating might easily fall off and have a seepage problem. If it is over 70 wt.-%, the fluidity might be too high and it might not be easy to apply. Furthermore, the surface of the coating might tend to fracture or crack. The amount of film forming geopolymer precursor is preferably 30 to 60 wt.-% and more preferably 45 to 50 wt.-%. The composition comprises 30 to 85 wt.-%, preferably 40 to 70 wt.-%, and more preferably 50 to 55 wt.-% geopolymer-containing filler particles, based on the total weight of the film forming geopolymer precursor and the geopolymer-containing filler particles. If the amount of geopolymer-containing filler particles is below 30 wt.-%, the coating might crack and fracture and the application structure might be inferior. If it is over 85 wt.-%, the adhesion might be inferior, the adhesion to the substrate might become weak, and the application properties might be inferior.

If the composition contains a too high amount of film forming geopolymer precursor the resultant coating tends to easily form cracks. If, however, the composition contains a too low amount of film forming geopolymer precursor then the resultant coating might not exhibit a sufficient geopolymeric character.

The geopolymer obtained from the film forming geopolymer precursor and the geopolymer present in the geopolymer-containing filler particles can be any type of geopolymer. Generally they can be the same or different and are preferably different. Geopolymers are well-known in the art and have been described in detail, e.g. by J. Davidovits. Geopolymers are inorganic silicoaluminate oxides. They typically have the general formula:

M_nKSi-O₂MAl-O₂Hn

wherein M is a monovalent cation, z defines the ratio of Si to Al, and n is the degree of polymerization.

M is typically an alkali metal, such as lithium, sodium or potassium.

The ratio of Si to Al defines the properties and thus the possible applications of the geopolymer. hi the present invention the ratio of Si : Al can be in the range of 1 : 1 to 35 : 1, preferably 1 : 1 to 3 : 1. Geopolymers having a ratio of Si : Al of 1 : 1 are also known as poly(sialate) or (M)-PS. Their general structure is often schematically shown as follows:

Geopolymers having a ratio of Si : Al of 2 : 1 are also known as poly(sialate-siloxo) or (M)-PSS. Their general structure is often schematically shown as follows:

(M)n(— Si— O— Al- O— Si— O— )„ O O O

Geopolymers having a ratio of Si : Al of 3 : 1 are also known as poly(sialate-disiloxo) or (M)-PSDS. Their general structure is often schematically shown as follows:

(M)n(— Si— O — Al- O— Si— O-Si— O— )_n O O O O

The degree of polymerization can vary greatly depending on the intended application.

FILM FORMING GEOPOL YMER PRECURSOR

The film forming geopolymer precursor can be any mixture of components from which a geopolymer can be prepared. For example the film forming geopolymer precursor can comprise aluminoasilicate, alkali metal silicate and alkali metal hydroxide. In one embodiment the film forming geopolymer precursor consists of aluminosilicate, alkali metal silicate and alkali metal hydroxide. The aluminosilicate is not particularly restricted as long as it is suitable for preparing a geopolymer. Typical examples are metakaolin, fly ash, coal gangue, zeolite and mixtures thereof (such as a mixture of fly ash and coal gangue). Preferably the aluminosilicate is metakaolin. The finer and whiter the metakaolin, the better the quality of the coating. For example, the size of the metakaolin should preferably be at most 43 μm.

The alkali metal silicate is not particularly restricted either as long as it is suitable for preparing a geopolymer. As examples of suitable alkali metal silicates lithium silicate, sodium silicate, potassium silicate and mixtures thereof can be given. Although the alkali metal silicates can be used alone, a combination of lithium silicate, sodium silicate, and potassium silicate is preferred. Depending on the desired form of the coating the alkali metal silicate can be included in the composition in the form of a dry powder or in liquid form.

An alkali metal hydroxide can also be present in the film forming geopolymer precursor. It can for example be selected from lithium hydroxide, sodium hydroxide, potassium hydroxide or mixtures thereof.

The ratio of the aluminosilicate, alkali metal silicate and alkali metal hydroxide will depend on the desired properties of the resultant geopolymer. For example, the mole ratio of the main chemical ingredients can be expressed as follows:

R₂O : SiO₂ : Al₂O₃ : H₂O= 1.00 : 2.08 ~ 5.16 : 0.37 ~ 1.98 : 0 ~ 8.7

R = cation which includes K⁺, Na⁺ and Li⁺.

GEOPOL YMER-CONTAFNING FILLER PARTICLES

In contrast to the film forming geopolymer precursor, which contains components that are not yet reacted to a geopolymer, the geopolymer-containing filler particles contain geopolymer. As was explained above, the geopolymer can be any type of geopolymer. Typically it is derived from aluminosilicate, alkali metal silicate and alkali metal hydroxide. The details of these three components are given above with respect to the film forming geopolymer precursor. The aluminosilicate, alkali metal silicate and alkali metal hydroxide, respectively, employed in the film forming geopolymer precursor and in the geopolymer-containing filler particles can be the same or different.

In the geopolymer-containing filler particles the ratio of aluminosilicate, alkali metal silicate and alkali metal hydroxide will depend on the desired properties of the resultant coating. Again the mole ratio of the main chemical ingredients can be expressed as follows:

R₂O : SiO₂ : Al₂O₃ : H₂O = 1.00 : 2.08 ~ 5.16 : 0.37 ~ 1.98 : 8.7

R = cation which includes K⁺, Na⁺ and Li⁺.

When the geopolymer-containing filler particles are prepared further components can be employed in addition to aluminosilicate, alkali metal silicate and alkali metal hydroxide. The types and amounts of these further components can vary significantly depending on the intended use of the resultant composition.

The geopolymer-containing filler particles can contain one or more fillers. The type of the fillers, their form (elongated, spherical, etc.) and their respective amounts can be chosen depending on the intended use of the resultant coating. Examples thereof include inorganic fillers such as quartz, talc, mica, wollastonite, diatomaceous earth, bentonite, kaolin, sepiolite, dolomite and aluminosilicates as well as organic fillers such as polymeric fibers, e.g. polypropylene fibers.

The color of the coating prepared from the composition according to the invention can be adjusted by incorporating one or more colorants such as organic or inorganic pigments into the geopolymer-containing filler particles. The type and amounts of the colorants can be chosen by a skilled person according to the requirements and are not restricted as long as the advantages of the invention are not impaired. As will be explained below, the coatings of the present invention can be used for various purposes. In order to modify the properties of the coating according to the needs, the geopolymer-containing filler particles can contain one or more optional components. The type and amount of the optional components will depend on the ultimate use of the geopolymer composition and are not particularly restricted. Examples of typical optional components are toughening agents, dispersing agents, plasticizers, levelling agents, and thickening agents. Furthermore, one or more functional agents which modify the properties of the geopolymer coating according to the intended use can be additionally contained in the composition used for preparing the geopolymer-containing filler particles.

Examples of such functional agents include: fire flame retardant agents (e.g., expanded graphite, melamine, hydrated glass powder, pentaerythritol, aluminum hydroxide); antimony trioxide, spherical closed cell expanded perlite, expanded vermiculite, fly ash particles, hollow glass beads, ceramic fiber powder, rockwool fiber powder); anti-rust agents (e.g., micaceous iron oxide, zinc metal, zinc powder, zinc oxide, glass flakes); antimicrobial agents (e.g., Ag₃PO₄-Zn₃(PO_-I)₂, (Ag-Zn) antimicrobial powder); stealth agent (e.g., high temperature ceramic metal oxide powder (cobalt, manganese, nickel, iron, barium, and zinc), iron carbonyl); conductive agents (e.g., iron carbonyl powder, silver-copper, silver-nickel, silver glass powder, silver mica powder); heat agent (e.g., aluminum powder, stainless steel powder); lubricants (e.g., graphite phosphate tablets, (MoS₂)); metal protective agent (e.g., alkali glass powder, silicon carbide powder); antifouling agents (e.g., cuprous oxide, capsaicin); temperature indication agent (e.g., Cu₂(HgI₄), C0C₁₂ six-tetramine); and anti-radiation agent (e.g., PbO, BaSO₄, Fe₂O₃). Both the types and the amounts of the functional agent can be selected by a skilled person based on his general knowledge of the field. In order to ensure that the advantages of the present invention are adequately provided the geopolymer-containing filler particles should include at least 5 wt.-% of geopolymer calculated as the sum of the weight of the aluminosilicate, alkali metal silicate and alkali metal hydroxide divided by the weight of the geopolymer-containing filler particles. The upper limit is not particularly limited. Any amount up to 100 wt.-%, preferably up to 90 wt.-%, geopolymer is possible. In order to assist in dispersing the various components of the composition used for preparing the geopolymer-containing filler particles a dispersing agent can be employed. The type of the dispersing agent will depend on the components to be dispersed and is not particularly restricted. Preferably Na₅P₃Oi_O is used as a dispersing agent.

Various types of plasticizers can be employed in the geopolymer-containing filler particles, if necessary. Polymerized melamine sulfonate can be given as an example. Of these, polymerized melamine sulfonate, such as that commercially available under the trade designation Melment FlO (BASF Construction Chemicals Austria GmbH, Austria), is preferred.

A hardening agent can be added when preparing the geopolymer-containing filler particles. Suitable types of hardening agents include NaSiF₆.

The geopolymer-containing filler particles can be prepared from the starting materials by any method which ensures that a geopolymer is formed. For example, in one embodiment all of the components, i.e. the aluminosilicate, the alkali metal silicate, and the alkali metal hydroxide as well as, if applicable, the filler, the colorant, the optional components and the functional agent, can be mixed together. This mixing step can either be dry mixing or wet mixing. If necessary, the size of the components can be reduced before or during the mixing step, e.g. by employing mill processing. The mixture is then evenly dispersed in water and subsequently hardened, e.g., in a mould. After hardening the resultant solid is preferably comminuted, hi another embodiment, part of the components are premixed and then the further components are incorporated before the addition of water. For example, it is preferable to premix the aluminosilicate, the alkali metal silicate, and the alkali metal hydroxide as well as, if applicable, the optional components. This premixing step can either be dry mixing or wet mixing. If necessary, the size of the components can be reduced before or during the mixing step, e.g. by employing mill processing. After premixing, the filler, the colorant, and the functional agent, if applicable, are mixed in. The mixture is then evenly dispersed in water and subsequently hardened, e.g. in a mould. After hardening the resultant solid is preferably comminuted. In both embodiments the hardening step is not particularly restricted. In general any hardening process which results in a geopolymer can be employed. For example, it is possible to harden the composition under ambient conditions. Depending on the components this can take, e.g., 3 days to 2 weeks. Alternatively it is possible to apply a suitable pressure and elevated temperatures (e.g., 50 to 150 ⁰C). hi this alternative the time required for hardening will be must shorter, e.g., 6 hours to 36 hours.

The size of the geopolymer composition obtained by hardening will typically have to be reduced in order to obtain geopolymer-containing filler particles. The size of the geopolymer- containing filler particles will depend on the type of coating which is to be prepared and can vary significantly. Preferably the geopolymer-particles have a size of less than 50 μm.

FURTHER COMPONENTS

In addition to the film forming geopolymer precursor and the geopolymer-containing filler particles the composition may contain further components depending on its intended use. The total amount of the further components should not negatively effect the geopolymeric characteristics of the cured composition.

The composition can contain one or more fillers. The type of the fillers, their form (elongated, spherical, etc.) and their respective amounts can be chosen depending on the intended use of the resultant coating. Examples thereof include inorganic fillers such as quartz, talc, mica, wollastonite, diatomaceous earth, kaolin, sepiolite, bentonite, dolomite and aluminosilicates as well as organic fillers such as polymeric fibers, e.g. polypropylene fibers.

The color of the coating prepared from the composition according to the invention can be adjusted by incorporating one or more colorants such as organic or inorganic pigments into the composition. The type and amounts of the colorants can be chosen by a skilled person according to the requirements and are not restricted as long as the advantages of the invention are not impaired. As will be explained below, the coatings of the present invention can be used for various purposes. In order to modify the properties of the cured composition according to the needs, the composition of the present invention can contain one or more optional components. The type and amount of the optional components will depend on the ultimate use of the geopolymer composition and are not particularly restricted. Examples of typical optional components are toughening agents, hydrophobic agents, dispersing agents, defoamers, plasticizers, and hardening agents.

Various types of toughening agents can be used. Examples thereof are ethylene/vinyl laurate/vinyl chloride terpolymers. One of the preferred toughening agents is a ethylene/vinyl laurate/vinyl chloride terpolymer, such as that commercialized under the trade designation VINNAP AS^® RI 551 Z from Wacker-Chemie GmbH, Germany. If the amount of toughening agent is too high, the obtained coating will tend to have a more organic character, while lower amounts tend to result in a more inorganic character.

The hydrophobic agent renders a cured composition which is obtained from the composition of the invention more hydrophobic. This might be desirable in some applications. Typical hydrophobic agents, which can be used in the invention, are a powder form silane on a carrier matrix. Of these the powder form silane on a carrier matrix is particularly preferred. A preferred commercial product is SILRES^® BS powder A from Wacker-Chemie GmbH, Germany.

In order to assist in dispersing the various components in the composition a dispersing agent can be added to the composition of the invention. The type of the dispersing agent will depend on the components to be dispersed and is not particularly restricted. Preferably Na₅P₃Oi₀ is used as a dispersing agent. The amount of dispersing agent will depend on the type of the dispersing agent and of the other components on the composition.

Some compositions might tend to foam when the composition is prepared for coating. This can be avoided by adding a defoamer to the composition. The type of defoamer will depend, e.g., on the component which causes the foaming problems. Examples of suitable defoamers are known in the art and include hydrocarbons and polyglycols supported on an inorganic carrier. Of these hydrocarbons and polyglycols supported on an inorganic carrier can be preferably used. An example of this type of defoamer is commercially available under the trade designation AGIT AN^® P 803 from Mϋnzing Chemie GmbH, Germany.

Various types of plasticizers can be employed in the compositions according to the present invention, if necessary. Polymerized melamine sulfonate can be given as an example. Of these polymerized melamine sulfonate, such as that commercially available under the trade designation Melment FlO (BASF Construction Chemicals Austria GmbH, Austria, is preferred.

NaSiF₆ has proved to be particularly suitable as a hardening agent.

The fillers, colorants and other optional components which are used when preparing the geopolymer-containing filler particles or which are contained in the final composition of the present invention, respectively, can be the same or different.

METHOD OF FORMING THE COMPOSITION

The composition according to the present invention can be prepared by mixing the film forming geopolymer precursor, the geopolymer-containing filler particles and, if applicable, the further components. The method of mixing the film forming geopolymer precursor, the geopolymer-containing filler particles and, if applicable, the further components is not particularly limited. For example, all of the components can be mixed together or alternatively some of the components can be premixed and the remaining components can be incorporated later.

COATINGS

The composition according to the present invention can be used to prepare a wide variety of coatings. Examples of possible coatings include anti-crack architectural coatings, waterproof architectural coatings, zinc-rich coatings, anti-crack insulation coatings, waterproof insulation coatings, fire resistant coatings, anti-rust coatings, anti-mildew coatings, stealth coatings which are invisible to radar waves, conductive coatings, heat-proof coatings, lubricating coatings, antioxidant and anti-oxidation coatings, anti-pollution coatings, temperature indication coatings, anti-radiation coatings, and waterproof coatings. The coatings can be suitable for indoor and/or outdoor applications. If desired the coatings can be flexible.

Generally the coating compositions can be provided in various forms. Illustrative examples are:

1) a single-component dry powder form. Water is added and is stirred in before application;

2) a single-component slurry form, which can be used directly;

3) a kit of two paste-like components, which are mixed with another before application;

4) a kit of two components: one in dry powder form and one in paste-like form, which are mixed together before application.

The method of preparing the single-component dry powder form is not particularly restricted. One possibility is the following method:

A. Filler, levelling agent, geopolymer-containing filler particles (metakaolin, alkali silicate resin, and alkali hydroxide) and water in a certain weight percentage are placed into a mixing tank, stirred and passed through a mesh screen.

B. The slurry is introduced into a spray dryer to disperse, heat and then granulate the slurry obtained in process A. This results in a solid powder. The solid powder is flowable due to a film of geopolymer-containing filler particles which forms on the surface of the other components. The solid particles are then placed into an insulated tank for self-hardening for 12 ~ 72 h.

C. The film forming geopolymer precursor (metakaolin, dry powder alkali silicate, alkali hydroxide), toughening agent, hydrophobic agent, dispersing agent, defoamer agent, levelling agent, thickening agent and hardening agent are dry mixed and crushed before adding the powder obtained in process B. Then the mixture is uniformly mixed again. D. Application method: The geopolymer-based coating combination in dry powder form is mixed with water in the proportion of 1:0.5 ~ 0.65 uniformly to achieve a proper consistency before application.

A further method of the present invention is illustrated in the following:

A. Film forming geopolymer precursor (metakaolin, alkali silicate in dry powder form, alkali hydroxide), further components, such as fillers and additives, are dry mixed and, if necessary, crushed again into a powder. This composition is also subject matter of the present invention.

B. Application method: mix geopolymer composition with water in a weight ratio of, e.g., 1 : 0,50 ~ 0.65 (water) before application.

The method for preparing a single-component slurry form is not restricted either. The following method can be given as an example.

A. Filler, levelling agent, geopolymer-containing filler particles (metakaolin, alkali silicate resin, alkali hydroxide) and water in a certain weight percentage are placed into a mixing tank, stirred and passed through a mesh screen.

C. The film forming geopolymer precursor (metakaolin, dry powder alkali silicate, alkali hydroxide), toughening agent, hydrophobic agent, dispersing agent, defoamer agent, levelling agent, thickening agent, hardening agent and water are mixed and wet crushed before adding the powder obtained in process B. Then the mixture is uniformly mixed again. D. Application method: direct use. The consistency can be regulated by the weight percentage of water.

Another illustrative method of the present invention is:

A. Film forming geopolymer precursor (metakaolin, alkali silicate resin, alkali hydroxide), further components (such as fillers and additives) and water are mixed and optionally crushed to form a slurry-like composition. This composition is subject matter of the present invention.

B. Application method: direct application.

The kit of two paste-like components can be prepared by various methods. One non-limiting method is described in the following:

C. Alkali silicate in dry powder form, alkali hydroxide, geopolymer-containing filler particles, toughening agent, hydrophobic agent, defoamer agent are mixed by a solid/liquid blender into paste-like form (component I).

D. Metakaolin, dispersing agent, defoamer agent, levelling agent, thickening agent, hardening agent and water are mixed by a solid-liquid blender into a paste-like form (component II). E. Application method: Components I and II are uniformly and evenly mixed in the proportion of, e.g., 1 : 1 before application. The consistency can be regulated by the weight percentage of water.

As a further possibility the following method of the present invention can be mentioned:

A. Metakaolin is mixed with water to form a slurry-like composition as component I.

B. Alkali silicate resin, alkali hydroxide is mixed with water to form a slurry-like composition as component II.

This two part kit is further subject matter of the present invention.

The distribution of the further components in to component I and component II is not particularly limited as long as all of the further components are present in either component I or component II. For example, all of the further components can be present in component I or all of the further components can be present in component II or part of the further components can be present in component I and part of the further components can be present in component II. If necessary, either or both of component I and component II can be ground to adjust the particle size.

C. Application method: component I and component II are evenly mixed in an appropriate weight ratio before application.

The kit of two components: one in dry powder form and one in paste-like form can be prepared by several different methods. For illustration purposes the following method is mentioned:

A. Filler, levelling agent, geopolymer-containing filler particles (metakaolin, alkali silicate resin, alkali hydroxide) and water in a certain weight percentage are placed into a mixing tank, stirred and passed through a mesh screen. B. The slurry is introduced into a spray dryer to disperse, heat and then granulate the slurry obtained in process A. This results in a solid powder. The solid powder is flowable due to a film of geopolymer-containing filler particles which forms on the surface of the other components. The solid particles are then placed into an insulated tank for self-hardening for 12

~ 72 h.

C. Alkali silicate in resin form, alkali hydroxide, geopolymer-containing filler particles, toughening agent, hydrophobic agent, defoamer agent are mixed by a solid/liquid blender into paste-like form (component I).

D. Metakaolin, toughening agent, hydrophobic agent, dispersing agent, defoamer agent, levelling agent, thickening agent, and hardening agent are dry mixed and crushed before the geopolymer-containing filler particles are added (component II).

E. Application method: Components I and II are uniformly and evenly mixed e.g. in the proportion of 1 : 1 before application. The consistency can be regulated by weight percentage of water.

METHOD OF MAKING A COATING

Prior art geopolymer compositions typically include film forming geopolymer precursor which is optionally mixed with further components. When a coating is prepared from such a composition the application of the coating composition and the hardening are typically conducted under conditions which are dictated by the coating process and the substrate to be coated. These conditions might not be optimal for forming the geopolymer or for incorporating any further components.

In contrast thereto the compositions according to the present invention comprise film forming geopolymer precursor and geopolymer-containing filler particles. Since the geopolymer- containing filler particles are preformed, it is possible to prepare and harden them under conditions which are optimal for the resultant coating and which are not dictated by the coating process and the substrate to be coated. Consequently the coatings according to the present invention have significantly improved mechanical properties compared to conventional geopolymer coatings, hi particular, with the present invention it is possible to provide coatings which have superior flexibility and levelling properties. They furthermore exhibit less exposed filler, cracking and peeling off the substrate.

EXAMPLES

The present invention is illustrated by the following examples, which are not to be construed as limiting.

Example 1 Film forming geopolymer precursor

Metakaolin 22 kg, sodium silicate dry resin (mole ratio of Al:Si 2.2) 30 kg, potassium silicate dry resin (mole ratio of Al:Si 2.2) 5 kg, lithium silicate dry resin (mole ratio of Al:Si 1.5) 1 kg, sodium hydroxide 2 kg, potassium hydroxide 1 kg, lithium hydroxide 0.5 kg, VINNAPAS RI551 Z 3 kg, SILRES BS Powder A 0.3 kg, Na₅P₃O₁₀ 0.6 kg, AGITAN P803 0.06 kg, MELMENT FlO 0.6 kg, PMC- 15US 0.2 kg, and NaSiF₆ 4 kg were mixed to obtain a dry powder.

Example 2 Premix for geopolymer-containing filler particles

Metakaolin 36 kg, sodium silicate liquid resin (mole ratio of Al:Si 1.2) 30 kg, potassium silicate liquid resin (mole ratio of Al:Si 1.6) 5 kg, lithium silicate liquid resin (mole ratio of AhSi 1.5) 1 kg, sodium hydroxide 2 kg, potassium hydroxide 1 kg, lithium hydroxide 0.5 kg, Na₅P₃O₁₀ 0.8 kg, AGITAN P803 0.06 kg, MELMENT FlO 0.45 kg, and NaSiF₆ 6 kg were mixed to obtain a dry powder. Example 3 Anti-crack & waterproof architectural coating (white color)

The premix for geopolymer-containing filler particles 30 kg, titanium dioxide 5 kg, ultramarine blue 0.01 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 95 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 15μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 35 kg, and polypropylene short fibers 0.01 kg until an average mixing degree of < 1 % was achieved.

Example 4 Zinc-rich coating

The premix for geopolymer-containing filler particles 7 kg, metal zinc powder 82 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 125 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 16μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 10 kg and sepiolite powder 1 kg until an average mixing degree of < 1 % was achieved.

Example 5 Anti crack & waterproof insulation coating

The premix for geopolymer-containing filler particles 16 kg, spherical closed cell expanded perlite 8 kg, expanded vermiculite 8 kg, fly ash hollow beads 20 kg, hollow glass beads 10 kg, diatomite 12 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 65 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 3 mm. The powder was then dried to a water level of < 2%. The powder was subsequently mixed with film forming geopolymer precursor 22 kg and rockwool fiber 4 kg until an average mixing degree of < 1 % was achieved.

Example 6 Fire resistant (indoor/outdoor) coating

The premix for geopolymer-containing filler particles 18 kg, melamine polyphosphate 10 kg, pentaerythritol 10 kg, expandable graphite 12 kg, hydrated glass 8 kg, aluminum hydroxide 5 kg, antimony oxide 2 kg, diatomite 12 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 65 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 21 kg and aluminosilicate fiber powder 2 kg until an average mixing degree of < 1 % was achieved.

Example 7 Anti-rust coating

The premix for geopolymer-containing filler particles 30 kg, micaceous iron oxide 20 kg, zinc phosphate 8 kg, zinc oxide 7 kg, glass scales 10 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 110 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2%. The powder was subsequently mixed with film forming geopolymer precursor 24 kg and polypropylene short fibers 0.1 kg until an average mixing degree of < 1 % was achieved. Example 8 Anti-mildew coating

The premix for geopolymer-containing filler particles 40 kg, Ag₃PO₄-Zn₃(PO₄)₂(Ag-Zn) antimicrobial compound powder 10 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 110 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 24 kg, sepiolite powder 6 kg, talcum powder 5 kg, and dolomite powder 15 kg until an average mixing degree of < 1 % was achieved.

Example 9 Stealth coating

The premix for geopolymer-containing filler particles 36 kg, high temperature ceramic metal oxide powder (cobalt, manganese, nickel, iron, barium, and zinc) 18 kg, iron carbonyl powder 20 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 135 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 25 kg and aluminosilicate fiber powder 1 kg until an average mixing degree of < 1 % was achieved.

Example 10 Conductive coating

The premix for geopolymer-containing filler particles 33 kg, phosphate tablets 17 kg, silver mica powder 5 kg, silver glass 12 kg, silver-copper powder 2 kg, silver nickel powder 2 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 86 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 28 kg and aluminosilicate fiber powder 1 kg until an average mixing degree of < 1 % was achieved.

Example 11 Heat-proof coating

The premix for geopolymer-containing filler particles 33 kg, stainless steel powder 10 kg, sepiolite powder 6 kg, aluminum powder 18 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 145⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 31 kg and aluminosilicate fiber powder 2 kg until an average mixing degree of < 1 % was achieved.

Example 12 Lubricating coating

The premix for geopolymer-containing filler particles 23 kg, phosphate tablets powder 32 kg, MoS₂ 6 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 86 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 35 kg and talcum powder 4 kg until an average mixing degree of < 1 % was achieved.

Example 13 Antioxidant and anti-oxidation coating

The premix for geopolymer-containing filler particles 13 kg, low-alkali glass powder 51 kg, silicon carbide powder 6 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 120 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 27 kg, sepiolite powder 2 kg, and aluminosilicate fiber powder 1 kg until an average mixing degree of < 1 % was achieved.

Example 14 Anti -pollution coating

The premix for geopolymer-containing filler particles 17 kg, cuprous oxide 25 kg, capsaicin alkali 12 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 55 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 38 kg, sepiolite powder 5 kg, and aluminosilicate fiber powder 3 kg until an average mixing degree of < 1 % was achieved.

Example 15 Temperature indication coating

The premix for geopolymer-containing filler particles 18 kg, CoCi₂ six urotropine 16 kg, kaolin 10 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 56 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 39 kg, dolomite powder 10 kg, sepiolite powder 6 kg, and aluminosilicate fiber powder 1 kg until an average mixing degree of < 1 % was achieved. Example 16 Anti-radiation coating

The premix for geopolymer-containing filler particles 27 kg, PbO 10 kg, BaSO₄ 19 kg, Fe₂O₃ 15 kg, and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed into a pressure tank at 86 ⁰C for 24 hours. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was then dried to a water level of < 2 %. The powder was subsequently mixed with film forming geopolymer precursor 27 kg, bentonite 1 kg, and aluminosilicate fiber powder 1 kg until an average mixing degree of < 1 % was achieved.

Example 17 Flexible waterproof coating

The premix for geopolymer-containing filler particles 38 kg, glass scales 17 kg, micaceous powder 15 kg and water were thoroughly mixed and subsequently put into a mould (200 mm x 200 mm x 200 mm). After the paste became solid, the mould was placed under normal atmosphere until the hardness reached 7d. After releasing it from the mould, the material was ground to a powder with a particle size of d < 44 μm. The powder was subsequently mixed with film forming geopolymer precursor 18 kg, VINNAPAS RI551 Z 12 kg, and polypropylene short fibers 0.1 kg. Finally water was added to adjust the water level to achieve a solid content of> 52%.

Implementation example 1

A. 1) Lithium hydroxide 2 kg, sodium silicate powder (mol = 2.4) 6 kg, 2) mix and blend them with water evenly, 3) achieve a thick liquid and then 4) add CdSeS (colouring auxiliary) 120 kg, 5) mix evenly, 6) then add metakaolin 16 kg, 7) blend it evenly to achieve thick liquid with a solid content of > 60%, 8) after stirring, the thick liquid is passed through a mesh screen (325 μm). B. 1) The thick liquid obtained in A is introduced into a spray dryer at 80 ~ 150 °C for granulation, 2) achieve geopolymer coated powder with a water content of 2 ~ 3 %, 3) load into a tank while it is hot, 4) seal for curing for 1 to 3 days, 5) achieve geopolymer coated pigment having a red colour 144 kg (excl. water).

C. 1) Metakaolin 391 kg, potassium hydroxide 49 kg, alkali silicate powder 137 kg, calcium carbonate 260 kg, additive Na₅PsOi₀ lkg, CMC 5 kg, dispersible emulsion powder 14 kg, 2) then dry mix them evenly and then 3) add the geopolymer coated red pigment 144 kg obtained from B, 4) blend evenly again, 5) achieve single component geopolymer coating composition 1000 kg.

Implementation example 2

A. 1) Potassium hydroxide 14 kg, sodium silicate powder (mol = 2.4) 53 kg, 2) then add water and blend evenly, 3) then add hollow microbeads 500 kg, 4) then blend evenly, 5) then add metakaolin 33 kg, 6) then mix evenly and 7) achieve a thick liquid with a solid content of > 60 %, 8) then pass the thick liquid through a mesh screen of 325 μm.

B. 1) The thick liquid obtained in A is introduced into a spray dryer at 80 ~ 150 °C for granulation to 2) achieve a geopolymer coated powder with a water content of 2 ~ 3%, 3) load into a tank while it is hot, 4) seal for curing for 1 to 3 days, 5) achieve geopolymer coated hollow microbeads 600 kg (excl. water).

C. 1) Metakaolin 70 kg, potassium hydroxide 32 kg, sodium silicate solution (mol = 2.4) 248 kg, zeolite powder 20 kg, additive Na₅P₃Oi₀ lkg, CMC 5 kg, dispersible emulsion powder 24 kg, 2) then mix them evenly with water and then 3) add geopolymer coated hollow microbeads obtained from B, 4) blend evenly, 5) achieve single-component geopolymer energy saving coating composition 1 ,000 kg. Implementation example 3

A. 1) Potassium hydroxide 12 kg, sodium silicate powder (mol = 2.4) 34 kg, 2) then add water, 3) then blend evenly into a thick liquid, 4) then add zirconium silicate 360 kg, 5) then blend evenly, 6) then add metakaolin 134 kg, 7) then stirring evenly and 8) achieve a thick liquid with a solid content of > 60 %, 9) then pass the thick liquid through a mesh screen of 325 μm.

B. 1) The thick liquid obtained in A is introduced into a spray dryer at 80 ~ 150°C for granulation to 2) achieve a geopolymer coated powder with a water content of 2 ~ 3%, 3) load into a tank while it is hot, 4) seal for curing for 1 to 3 days, 5) then achieve geopolymer coated zirconium silicate powder 540 kg (excl. water).

C. 1) Potassium silicate 17 kg, sodium silicate solution (mol = 2.4) 110 kg, additive Na₅P₃Oi₀ 1 kg, CMC 5 kg, dispersible emulsion powder 14 kg, 2) then mix them evenly with water and then 3) add the geopolymer coated zirconium silicate powder obtained from B 353 kg, 4) blend evenly, 5) achieve two-component geopolymer infrared radiation coating composition's component I 500 kg.

D. 1) Metakaolin 193 kg, H₂O 120 kg, geopolymer coated zirconium silicate powder 187 kg, 2) then mix them evenly, then 3) achieve two-component geopolymer infrared radiation coating composition's component II 500 kg.

Implementation example 4

A. 1) Potassium hydroxide 18 kg, sodium silicate powder (mol = 2.4) 53 kg, 2) place them into a mixing tank, 3) then add water, 4) then blend evenly, 5) then add metal lead powder 400 kg, 6) then blend evenly, 7) then add metakaolin 129 kg, 8) then mix and stir evenly into a thick liquid with a solid content of > 60 %, 9) then pass the thick liquid through a mesh screen of 325 μm. B. 1) The thick liquid obtained in A is introduced into a spray dryer at 80 ~ 150°C for granulation to 2) achieve a geopolymer coated powder with a water content of 2 ~ 3%, 3) load into a tank while it is hot, 4) seal for curing for 1 to 3 days, 5) achieve the geopolymer coated metal lead powder 600 kg (excl. water).

C. 1) Potassium hydroxide 14 kg, sodium silicate solution (mol = 2.4) 88 kg, barium sulphate 100 kg, H₂O 80 kg, additive Na₅P₃Oi_O lkg, CMC 5 kg, dispersible emulsion powder 14 kg, 2) then wet mix them evenly, 3) add the geopolymer coated metal lead powder obtained from B 198 kg, 4) blend evenly, 5) achieve two-component geopolymer shielding coating composition's component I 500 kg.

D. 1) Metakaolin 98 kg, the geopolymer coated metal lead powder 402 kg obtained from B, 2) then dry mix them evenly and then 3) achieve two-component geopolymer shielding coating composition's component II 500 kg.

Implementation example 5

1) Sodium hydroxide 16 kg, sodium silicate powder (mol = 2.49) 47 kg, metakaolin 87 kg, metal zinc powder @ 800 μm 830 kg, additive Na₅P₃Oi₀ 1 kg, CMC 5 kg, dispersible emulsion powder 14 kg, 2) dry mix them evenly at a fineness of < 16 μm, 3) achieve single component geopolymer zinc -rich coating composition 1000 kg.

Implementation example 6

1) Potassium hydroxide 63 kg, sodium silicate solution (mol = 2.4) 497 kg, metakaolin 140 kg, mineral carbon @ 325 μm 280 kg, additive Na₅P₃Oi₀ lkg, CMC 5 kg, dispersible emulsion powder 14 kg, 2) place into a mixing tank, 3) wet mix them evenly at a fineness of < 16 μm, 4) achieve single-component geopolymer conductive coating composition 1000 kg. Implementation example 7

A. 1) Potassium hydroxide 24 kg, sodium silicate solution (mol = 2.4) 141 kg, iron oxide red @ 325 μm 120 kg, glass flakes @ 325 μm 55 kg, mica iron oxide @ 325 μm 50 kg, additive Na₅P₃O₁₀ 50 kg, 2) place into a mixing tank, 3) wet mix them evenly at a fineness of < 16 μm, to 4) achieve a two-component geopolymer anticorrosive coating composition's component I 440 kg.

B. 1) Metakaolin 135 kg, glass flakes @ 200 μm 300 kg, CMC 1 kg, silicone-acrylic emulsion 14 kg, H₂O 110 kg, then 2) wet mix them evenly at a fineness of < 16 μm, 3) achieve two- component geopolymer anticorrosive coating composition's conponent II 560 kg.

Claims

1. A composition comprising:

(i) 15 to 70 wt.-% film forming geopolymer precursor; and

2. The composition according to claim 1, wherein the composition comprises 30 to 60 wt.- % film forming geopolymer precursor, based on the total weight of the film forming geopolymer precursor and the geopolymer-containing filler particles.

3. The composition according to claim 2, wherein the composition comprises 45 to 50 wt.- % film forming geopolymer precursor, based on the total weight of the film forming geopolymer precursor and the geopolymer-containing filler particles.

4. The composition according to any of claims 1 to 3, wherein the composition comprises 40 to 70 wt.-% geopolymer-containing filler particles, based on the total weight of the film forming geopolymer precursor and the geopolymer-containing filler particles.

5. The composition according to claim 4, wherein the composition comprises 50 to 55 wt- % geopolymer-containing filler particles, based on the total weight of the film forming geopolymer precursor and the geopolymer-containing filler particles.

6. The composition according to any of claims 1 to 5, wherein the film forming geopolymer precursor comprises aluminosilicate, alkali metal silicate and alkali metal hydroxide.

7. The composition according to any of claims 1 to 5, wherein the geopolymer-containing filler particles comprise geopolymer and one or more further components selected from the group consisting of fillers, colorants, dispersing agents, plasticizers, hydrophobic agents, hardening agents and functional agents.

8. The composition according to any of claims 1 to 7, wherein the composition further comprises one or more further components selected from the group consisting of fillers, colorants, toughening agents, hydrophobic agents, dispersing agents, defoamers, plasticizers, and hardening agents.

9. The composition according to any of claims 1 to 8, wherein the mole ratio of the main chemical ingredients of the film forming geopolymer precursor is

R₂O : SiO₂ : Al₂O₃ : H₂O= 1.00 : 2.08 ~ 5.16 : 0.37 ~ 1.98 : 0 ~ 8.7

R = K⁺, Na⁺ and Li⁺.

10. A method of forming the composition according to any of claims 1 to 9, the method comprising the steps of:

(a) providing geopolymer particles; and

(b) mixing the geopolymer particles with the film forming geopolymer precursor.

11. A coating obtainable from the composition as defined in any of claims 1 to 9.

12. The coating according to claim 11, wherein the coating is selected from the group consisting of architectural coatings and functional coatings.

13. Use of the composition as defined in any of claims 1 to 9 for the preparation of a coating.