Field of the Invention

The present invention relates to an inorganic insulation material, which has a low thermal conductivity coefficient and is designated as class Al fire rated, and production of this material via geopolymerization method. Background of the Invention

Typically polystyrene based materials are used in the commercially produced thermal insulation materials. Processing of polystyrene insulation materials is easy. However, the facts that it has low fire resistance and that the material used is imported are its disadvantages. Rock wool and fiberglass are also used as thermal insulation materials. However, the facts that these materials are deformed upon impacts and that their thermal conductivity coefficient increases by time since their steam diffusion resistance is low cause disadvantages. These materials belong to Al - A2 group non-combustion class and can resist up to 700°C.

Since the insulation materials obtained by geopolymerization are inorganic, they are designated as class Al fire rated and since they have a hard structure they are more resistant than fiberglass and rock wool. Geopolymerization is a material production technique which is basically applied by dissolution by the help of amorphous alumina- silicates such as metakaolin and alkaline hydroxides, and by condensation below 100°C. Recently, studies on production of porous insulation materials by this method have increased. Stability of the foam produced in the insulation materials produced by geopolymerization is important. Liquid foams are thermodynamically unstable since they have a high gas-liquid interfacial area. There are several parameters that cause unstability:

Drainage (channeling),

Coalescence,

- Ostwald ripening chemical reaction.

Channels are the physical separation between the gas and liquid phases of the foam under the influence of gravity. While lightweight gas bubbles form a layer on the upper part, the heavier liquid phase gets denser at the lower part. The foams are characterized by a three dimensional structure. Intercellular surfaces are comprised of a thin film. Intersection point of three neighboring thin films is called the "Plateau borders".

Cases where coalescence and drainage are not sufficiently stable may also occur. Stability of the thin film is determined by the repulsive and attractive forces between the bubbles. Van der Waals attractive forces tend to push the bubbles against each other (negative disjoining pressure) and thus provide the main driving force for collapse of the thin film. Coalescence can be prevented by having the electrostatic and/or steric repulsive forces stronger than the Van der Waals attractive forces. This can be possible by having the surfactant molecules or particles attached to the air-water surface area. It may be possible to prevent drainage and coalescence processes; however Ostwald ripening can sometimes be prevented for a long term ¹ . In the study conducted by W.D.A. Rickard et al., a process is developed for producing fire-resistant insulation materials by geopolymerization technique. However, using alumina salt as the foaming agent in the said study has increased thermal conductivity coefficient. Furthermore, homogeneity could not be obtained in pore distribution of the samples. Therefore, macro pore percentage of the

¹ A. R. Studart, U. T. Gonzenbach, E. Tervoort ve Ludwig J. Gauckler. Processing Routes to Macroporous Ceramics: A Review. J. Am. Ceram. Soc, 89 [6] 1771-1789 (2006). samples remained under 50% and the densities were high. In connection to all of these results, thermal conductivity of the insulation material was found to be above 0.065 W/mK ² . In another study, LUO YU-ping et al. have synthesized a thermal insulation material by using sorel cement and hydrogen peroxide, without applying steam curing and firing. Properties such as apparent density, bending strength, compressive strength, thermal conductivity, water resistance and thermal tolerance were characterized and their influences on the performance were discussed. It was determined that the said material had an apparent density of 360 kg/m ³ , a compressive strength of 1,86 MPa, a thermal conductivity coefficient of 0.072 W/mK, and a thermal tolerance temperature of 300°C. As a result, thermal conductivity coefficient remained above the value of 0.065 W/mK ³ . By means of the non-combustible inorganic insulation material of the present invention having low thermal conductivity coefficient, the problems in the known art are solved. Production of this material by geopolymerization technique with an environment friendly method can be enabled. Summary of the Invention

The objective of the present invention is to provide an inorganic insulation material designated as class A 1 -fire rated and having a thermal conductivity coefficient below 0.065 W/K.

Another objective of the present invention is to provide the inorganic insulation material by using geopolymerization method.

² W. D.A. Rickard, L. Vickers, A. V. Riesse, Performance of fibre reinforced, low density metakaolin geopolymers under simulated fire conditions. Applied Clay Science 73 (2013) 71-77.

³ LUO Yu-ping, WANG Li-jiu, Research on non-steam-cured and non-fired fly-ash thermal insulating materials. J China Univ Mining & Technol 18 (2008) 0116-0121. Detailed Description of the Invention

The inorganic insulation material, which is developed to fulfill the objective of the present invention and used for providing thermal insulation, basically comprises 40-55% by weight of metakaolin, 45-60% by weight of water glass, 5-6% by weight of sodium hydroxide and 2-3% by weight of hydrogen peroxide.

In the preferred embodiment of the invention, 0.5-1% by weight of propyl gallate was added to the mixture in order to ensure pore stability.

The composition of the inorganic insulation material of the present invention comprises 3-4% by weight of S1O2/AI2O3 and 0.25-0.35% by weight of Na ₂ 0/Si0 ₂ . Thermal conductivity coefficient of the inorganic insulation material of the present invention is smaller than 0.065 W/mK and therefore t is non-combustible and designated as class Al-fire rated.

Density of the inorganic insulation material of the present invention is within the range of 0.190-0.250 g/cm ³ .

Geopolymerization method is used for producing the inorganic insulation material of the present invention. Geopolymerization method developed to fulfill the objective of the present invention is illustrated in the accompanying figure, in which;

Figure 1 shows the steps of the geopolymerization method. The method steps given in Figure 1 are assigned reference numbers as follows:

100. Geopolymerization method 101. Preparing the geopolymeric viscose paste by mechanically metakaolin, water glass and sodium hydroxide

102. Allowing the prepared viscose paste to rest at room temperature

103. Mechanically adding hydrogen peroxide solution to the mixture

104. Pouring the viscose paste into the molds and allowing it to rest

105. Drying the viscose paste at a temperature of 65-85°C

106. Removing the product from the mold

107. Leaving the product at dry atmospheric conditions The geopolymerization method (100) developed to fulfill the objective of the present invention comprises the steps of

- preparing the geopolymeric viscose paste by mechanically mixing metakaolin, water glass and sodium hydroxide (101),

- allowing the prepared viscose paste to rest at room temperature (102),

- mechanically adding hydrogen peroxide solution to the mixture (103),

- pouring the viscose paste into the molds and allowing it to rest (104),

- drying the viscose paste at a temperature of 65-85°C (105),

- removing the product from the mold (106),

- leaving the product at dry atmospheric conditions (107).