FIELD

The present disclosure relates to a cool roof and a process for its preparation.

DEFINITIONS

As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicates otherwise.

Cool roof: the term “cool roof’ refers to a roofing system that delivers high reflectance (the ability to reflect the visible, infrared and ultraviolet wavelength of the sun, reducing heat to the building) and high thermal emittance (the ability to release a large percentage of absorbed, or non-reflected, solar energy).

Endless felt: the term “endless felt” refers to a part in Hatschek machine which is used to produce fiber cement product. It has fixed length and width and has no joint in-between and fabricated as a continuous single endless component.

Moving felt: the term “moving felt” refers to an endless component which continuously moves on a set of rollers such as rotating sieves, rotating rollers and the like. This makes ‘felt’ to enable to pick a thin layer of pulp from each moving sieve cylinders and transfer this to a forming drum (bole).

Template: the term “template” refers to a shaped piece of the rigid coated steel material which is used as a pattern for the processes such as cutting out, shaping, or drilling.

Profile sheet: the term “profile sheet” refers to a structure or a pattern formed on the sheet. The profile sheets are suitable for installing as roofing material and also cladding material.

Operative surface: the term “operative surface” refers to a surface on which the coating composition is applied.

Sieve cylinders: the term “sieve cylinders” refers to the cylinders which are used in Hatschek machine. The sieve cylinders are suitable for rotating in a bath which is filled with pulp premix, wherein a fluid medium flows from the premix through the sieve, and wherein a thin layer of pulp premix remains on the sieve to form a layer.

Emissivity: the term “emissivity” refers to the ratio of an energy radiated from a surface of a material to that radiated from a perfect emitter, known as a blackbody, at the same temperature and the wavelength, under the same viewing conditions.

Solar Reflectance Index (SRI): the term “solar reflectance index or SRI” refers to an indicator, of the ability of the roof surface to return the solar energy to the atmosphere.

BACKGROUND

The background information herein below relates to the present disclosure but is not necessarily prior art.

In recent years, with a rapid development in the industry and an improvement in the living standards, the power demanded is exponentially increasing, while the amount of power supplied is comparatively limited. Thus, energy saving has become an important aspect while designing the infrastructures. In particular, the peak power demand is recorded during the summers. This is due to the use of electric appliances such as air conditioners, coolers, fans and the like that consume more power.

Generally, dark coloured roofs are available in the market. During summer, the temperature at the outer surface of the dark coloured roof can increase as much as 90 °F. In the midsummers, the temperatures on the outer surface of the dark coloured roofs rise to 150-190 °F (66 to 88 °C). This heat increase not only contributes to reduced indoor comfort and higher utility bills, but also accelerates the deterioration of the roofing materials, in turn increasing the roof maintenance costs.

Furthermore, the conventional roof sheets are highly porous and tend to absorb more moisture due to raw materials such as asbestos, cellulose and the like. In a tropical climate, when the roof sheets are exposed to rains, within a year or two, the roof sheets are prone to microbial growth staining. Further, the typical tropical climatic conditions are favourable for algal and fungal growth. A continuous exposure to these conditions not only leads to staining of the roof sheets, but also creates health-related problems. Some of the manufacturers provide paints for coating such roof sheets. However, painting of the roof sheets on a commercial scale is a costly process. Furthermore, in the tropical climate, the exposure to heavy rains reduces the durability of the applied paints.

In recent times, various types of acrylic coatings have been used on roofing materials to form energy-efficient roofing materials. However, moisture and air pockets can be trapped under the acrylic coatings. These moisture and air pockets lead to blisters or pinholes in the cured acrylic coating. Further, the inconsistent coverage and potential cracking of areas where the coating is applied too heavily, can lead to additional problems related to the application of the acrylic coatings.

There is, therefore, felt a need to provide a cool roof and a process for preparing the same that overcomes the above-mentioned drawbacks.

OBJECTS

Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.

It is an object of the present disclosure to ameliorate one or more problems of the background or to at least provide a useful alternative.

Another object of the present disclosure is to provide a process for preparing a cool roof.

Yet another object of the present disclosure is to provide a process for preparing a cool roof which requires less labour, is cost-effective, is highly productive and is eco-friendly.

Still another object of the present disclosure is to provide a process for preparing a cool roof which comprises a substrate and a coating composition.

Yet another object of the present disclosure is to provide a cool roof having high solar reflectance index (SRI) and high thermal emittance properties.

Still another object of the present disclosure is to provide a cool roof having water repellency, anti-fungal and anti-algal properties.

Yet another object of the present disclosure is to provide a cool roof having high aesthetic value. Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to Emit the scope of the present disclosure.

SUMMARY

The present disclosure relates to a process for preparing the cool roof. The process comprises the steps of mixing a predetermined amount of a first fluid medium to a predetermined amount of a substrate composition for a first predetermined time period to obtain a premix. The predetermined number of layers of the premix is formed by using an endless felt on a plurality of sieve cylinders. The predetermined numbers of the layers are stacked on a rotating metallic drum to form a stack of layers. Excess water is removed from the stack of layers on a moving felt by using a vacuum system followed by further removing the excess water from the stack of layers by squeezing the layers between a forming drum and press roller to form a substrate having an operative top layer. The operative top layer of the substrate is coated with the coating composition to obtain the cool roof having a predetermined thickness.

DETAILED DESCRIPTION

The present disclosure relates to a cool roof and a process for its preparation.

Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details, are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.

The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.

As used herein, the term "and/or" includes any and all combinations of one or more of the associated hsted elements.

The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.

Generally, dark coloured roofs are available in the market. During summer, the temperature at the outer surface of the dark coloured roof can increase as much as 90 °F. In the midsummers, the temperatures on the outer surface of the dark coloured roofs rise to 150-190 °F (66 to 88 °C). This heat increase not only contributes to reduced indoor comfort and higher utility bills, but also accelerates the deterioration of the roofing materials, in turn increasing the roof maintenance costs.

The present disclosure provides a cool roof and a process for preparing a cool roof.

The process preparing the cool roof comprises the following steps: i) mixing a predetermined amount of a first fluid medium to a predetermined amount of a substrate composition for a first predetermined time period to obtain a premix; ii) forming a predetermined number of layers of the premix by using an endless felt on a plurality of sieve cylinders; iii) stacking the predetermined number of layers on a rotating metallic drum to form a stack of layers; iv) removing excess water from the stack of layers on a moving felt by using a vacuum system followed by further removing excess water from the stack of layers by squeezing the layers between a forming drum and press roller to form a substrate having an operative top layer; and v) coating the operative top layer of the substrate with a coating composition to obtain the cool roof having a predetermined thickness.

The process is described in detail herein below.

In a first step, a predetermined amount of a first fluid medium is mixed with a predetermined amount of a substrate composition and stirred for a first predetermined time period to obtain a premix.

In an embodiment of the present disclosure, the first fluid medium is water.

In an embodiment of the present disclosure, the predetermined amount of the first fluid medium is in the range of 20 mass % to 40 mass %. In an exemplary embodiment of the present disclosure, the predetermined amount of the first fluid medium is 30 mass%, wherein the mass% is with respect to the total mass of the premix.

In an embodiment of the present disclosure, the predetermined amount of the substrate composition is in the range of 50 mass% to 80 mass%. In an exemplary embodiment of the present disclosure, the predetermined amount of the substrate composition is 70 mass%, wherein the mass% is with respect to the total mass of the premix.

In an embodiment of the present disclosure, the first predetermined time period is in the range of 5 minutes to 20 minutes. In an exemplary embodiment of the present disclosure, the first predetermined time period is 10 minutes.

In a second step, a predetermined number of layers are formed of the premix by using an endless felt on a plurality of sieve cylinders.

In an embodiment of the present disclosure, the predetermined numbers of layers are in the range of 4 to 8. In an exemplary embodiment of the present disclosure, the predetermined number of layers is 6.

In a third step, the predetermined numbers of layers are stacked on a rotating metallic drum to form a stack of layers. In accordance with another embodiment of the present disclosure, the formation of the predetermined number of layers of the premix on the plurality of separate sieve cylinders is synchronized with each other.

In a fourth step, excess water from the stack of layers is removed on a moving felt by using a vacuum system followed by further removing the excess water from the stack of layers by squeezing the layer between forming drum and press roller to form a substrate having an operative top layer.

In a fifth step, the operative top layer of the substrate is coated with a coating composition to obtain the cool roof having a predetermined thickness.

In an embodiment of the present disclosure, the predetermined thickness is in the range of 5.5 mm to 6.5 mm. In an exemplary embodiment of the present disclosure, the predetermined thickness is 6.0 mm.

In an embodiment of the present disclosure, the coating on the substrate has a thickness in the range of 0.10 mm to 0.3 mm.

In an embodiment of the present disclosure, the operative top layer is coated with the coating composition by using online atomizer spray coating.

The online atomizer spray coating is decided on factors such as depth of coating required and variations of pigment paste viscosity.

The cool roof produced by online atomizer spray coating based pigment impregnation gives aesthetic, water repellent, antifungal and temperature reduction properties on the roof surface to reduce the heat inside the room.

The online spraying process for coating the top operative layer of the substrate enables to get a production output of 350 to 400 tons of cool roof sheet per day which is higher as compared to any other conventional coating method or manual painting.

In an embodiment, the present disclosure provides a cool roof. The cool roof comprises a substrate, having an operative top layer and a coating composition coated on the operative top layer of the substrate. In an embodiment of the present disclosure, the substrate is selected from the group consisting of asbestos based substrate and non asbestos based substrate. In an exemplary embodiment of the present disclosure, the substrate is asbestos based substrate. In another exemplary embodiment of the present disclosure, the substrate is non asbestos based substrate.

In an embodiment of the present disclosure, the substrate composition comprises a first mixture and a second mixture in a mass ratio in the range of 1:8 to 1:12. In an exemplary embodiment of the present disclosure, the mass ratio of the first mixture to the second mixture is 1:10.

The first mixture comprises a secondary pulp, synthetic fibers, and optionally, optionally, a primary pulp, optionally, primary pulp and asbestos fibers.

The second mixture comprises cement, fly ash, first filler and a mineral additive.

In an embodiment of the present disclosure, the primary pulp is at least one selected from the group consisting of cellulosic pulp and soft wood kraft pulp.

In an embodiment of the present disclosure, the soft wood kraft pulp is at least one selected from unbleached soft wood pulp and bleached soft wood pulp. In an exemplary embodiment of the present disclosure, the soft wood kraft pulp is bleached soft wood kraft pulp.

In an embodiment of the present disclosure, the moisture content of the primary pulp is in the range of 5 mass% to 15 mass% of the total mass of the primary pulp. In an exemplary embodiment of the present disclosure, the moisture content of the primary pulp is 10 mass% of the total mass of the primary pulp.

In an embodiment of the present disclosure, the secondary pulp is selected from the group consisting of waste packaging materials, used cement bags, cuttings of virgin pulp and cotton rag pulp. In an exemplary embodiment of the present disclosure, the secondary pulp is used cement bags.

In an embodiment of the present disclosure, the waste packaging materials are chopped and processed to remove lignin and other unwanted chemicals.

In accordance with the embodiment of the present disclosure, the moisture content of the secondary pulp is in the range of 5 mass% to 15 mass% of the total mass of the secondary pulp. In an exemplary embodiment of the present disclosure, the moisture content of the secondary pulp is 10 mass% of the total mass of the secondary pulp.

In an embodiment of the present disclosure, the synthetic fibers are at least one selected from the group consisting of denim fibers, cotton fibers, polymeric fibers and waste clothes. In an exemplary embodiment of the present disclosure, the synthetic fibers are polymeric fibers.

In an embodiment of the present disclosure, the polymeric fibers are selected from the group consisting of polyester, polyvinyl alcohol and polypropylene. In an exemplary embodiment, the polymeric fiber is polyester. In another exemplary embodiment, the polymeric fiber is polyvinyl alcohol.

In an embodiment of the present disclosure, the synthetic fibers are treated with a predetermined amount of water in a fiber mixer having a high speed stirrer to obtain a fiber slurry.

In an embodiment of the present disclosure, the moisture content of the fiber slurry can be up to 50 mass% of the total mass of the fiber pulp. In an exemplary embodiment of the present disclosure, the moisture content of the fiber pulp is 10 mass%.

In an exemplary embodiment of the present disclosure, the first mixture optionally comprises asbestos fibers. In an exemplary embodiment of the present disclosure, the asbestos fibers are present in the first mixture. In another exemplary embodiment of the present disclosure, the asbestos fibers are absent in the first mixture.

Asbestos fibers are the naturally occurring silicates which are commonly used in the construction materials such as cement and insulation and in many other textiles. Asbestos fibers are used as insulation against heat and fire in buildings.

In accordance with the embodiments of the present disclosure, the asbestos fibers can be initially ground with a small quantity of water in a fiber mill for the opening of the fibers, leading to disintegration of the fibers. Such opened fibers can be passed into a fiber mill and then further opened using a high speed rotating stirrer systems.

In an embodiment of the present disclosure, the first filler is recycled materials. The recycled material is ground waste of rejected substrate. In an embodiment of the present disclosure, the mineral additives are selected from the group consisting of calcite, wollastonite and kaolin. In an exemplary embodiment of the present disclosure, the mineral additive is kaolin. In another exemplary embodiment of the present disclosure the mineral additive is a combination of wollastinite and calcite.

In an embodiment of the present disclosure, the substrate composition is prepared by a process comprising the following steps: i) mixing predetermined amounts of a secondary pulp, synthetic fibers; and optionally, a primary pulp and asbestos fibers for a time period in the range of 5 minutes to 20 minutes to obtain a first mixture; ii) separately mixing predetermined amounts of cement, fly ash, silica, at least one first filler and at least one additive for a time period in the range of 5 minutes to 10 minutes to obtain a second mixture; and iii) combining the first mixture and the second mixture in a predetermined ratio for a time period in the range of 3 minutes to 5 minutes to obtain the substrate composition.

In an embodiment of the present disclosure, the predetermined amount of primary pulp is in the range of 0 mass% to 5 mass% with respect to the total mass of the substrate composition. In an exemplary embodiment of the present disclosure, the predetermined amount of primary pulp is 2 mass % with respect to the total mass of the substrate composition.

In an embodiment of the present disclosure, the predetermined amount of secondary pulp is in the range of 1.5 mass% to 5 mass% with respect to the total mass of the substrate composition. In an exemplary embodiment of the present disclosure, the predetermined amount of secondary pulp is 2 mass % with respect to the total mass of the substrate composition.

In an embodiment of the present disclosure, the predetermined amount of synthetic fibers is in the range of 0.2 mass% to 5 mass% with respect to the total mass of the substrate composition. In an exemplary embodiment of the present disclosure, the predetermined amount of synthetic fibers is 2 mass % with respect to the total mass of the substrate composition. In another exemplary embodiment of the present disclosure, the predetermined amount of synthetic fibers is 0.5 mass % with respect to the total mass of the substrate composition.

In an embodiment of the present disclosure, the asbestos fibers is in the range of 0 mass% to 12 mass%, with respect to the total mass of the substrate composition. In an exemplary embodiment of the present disclosure, the predetermined amount of asbestos fibers is 5 mass % with respect to the total mass of the substrate composition. In another exemplary embodiment of the present disclosure, the asbestos fibers are not present.

In an embodiment of the present disclosure, the predetermined amount of cement is in the range of 45 mass% to 80 mass% with respect to the total mass of the substrate composition. In an exemplary embodiment of the present disclosure, the predetermined amount of cement is 72 mass % with respect to the total mass of the substrate composition. In another exemplary embodiment of the present disclosure, the predetermined amount of cement is 52 mass % with respect to the total mass of the substrate composition.

In an embodiment of the present disclosure, the predetermined amount of fly ash is in the range of 10 mass% to 40 mass% with respect to the total mass of the substrate composition. In an exemplary embodiment of the present disclosure, the predetermined amount of the fly ash is 15 mass % with respect to the total mass of the substrate composition. In another exemplary embodiment of the present disclosure, the predetermined amount of the fly ash is 35 mass % with respect to the total mass of the substrate composition.

In an embodiment of the present disclosure, the predetermined amount of a first filler is in the range of 3 mass% to 8 mass% with respect to the total mass of the substrate composition. In an exemplary embodiment of the present disclosure, the predetermined amount of the first filler is 5 mass % with respect to the total mass of the substrate composition.

In an embodiment of the present disclosure, the predetermined amount of an mineral additive is in the range of 0.2 mass% to 3 mass% with respect to the total mass of the substrate composition. In an exemplary embodiment of the present disclosure, the predetermined amount of the additive is 0.5 mass % with respect to the total mass of the substrate composition. In another exemplary embodiment of the present disclosure, the predetermined amount of the additive is 2 mass % with respect to the total mass of the substrate composition. In an embodiment of the present disclosure, the mass ratio of the first mixture to the second mixture is in the range of 1:8 to 1:12. In an exemplary embodiment of the present disclosure, the mass ratio of the first mixture to the second mixture is 1:10.

The cement is prepared in a cement mixer, flyash is prepared in a flyash mixer, fiber is mixed in a fiber mixer and finally all these materials are taken into main mixer by using Programmable Logic Controller (PLC) control system with the help of load cell arrangement through conveyor feeding system to have precise control on mass percentage of each material.

Combining the first mixture and the second mixture in a predetermined ratio in the range of 1:8 to 1:12 to obtain the substrate composition. In an exemplary embodiment of the present disclosure, the mass ratio of the first mixture to the second mixture is 1:10.

In an embodiment of the present disclosure, the coating composition comprises:

• 15 mass% to 50 mass% of a white pigment paste;

• 5 mass% to 15 mass% of at least one extender;

• 0.5 mass% to 5 mass% of at least one water repellent additive;

• 0.5 mass% to 5 mass% of at least one biocide;

• 5 mass% to 15 mass% of at least one first binder;

• 5 mass% to 15 mass% of at least one second filler;

• 5 mass% to 15 mass% of at least one insulating material; and

• q.s. water, wherein the mass% of each component is with respect of the total mass of the coating composition.

In an embodiment of the present disclosure, the white pigment paste comprises a white pigment and a second fluid medium in a mass ratio in the range of 1:0.5 to 1:2. In an exemplary embodiment of the present disclosure, a white pigment and a second fluid medium is in a mass ratio of 1 : 1.

In an embodiment of the present disclosure, the white pigment is at least one selected from the group consisting of titanium based pigment, barium based pigment, antimony based pigment and lead-based pigment. In an exemplary embodiment of the present disclosure, the white pigment is lead-based pigment. In an embodiment of the present disclosure, the Titanium based pigment is rutile.

The antimony based pigment or lead based pigment can be added due to their high refractive index.

In an embodiment of the present disclosure, the second fluid medium is water.

In an embodiment of the present disclosure, the extender is at least one selected from the group consisting of phyllosilicate minerals, sodium silicate and gypsum. In an exemplary embodiment of the present disclosure, the extender is phyllosilicate mineral.

In an embodiment of the present disclosure, the water repellent additive is at least one selected from the group consisting of polymethylhydrosiloxanes, siliconates, silane-siloxane and active silicates. In an exemplary embodiment of the present disclosure, the water repellent additive is polymethylhydrosiloxanes.

In an embodiment of the present disclosure, the biocide is at least one selected from the group consisting of allylamines, azoles, and metal complexes of isothiazolinone, pyrithione, and thiocyanate. In an exemplary embodiment of the present disclosure, the biocide is azole.

In an embodiment of the present disclosure, the first binder is at least one selected from the group consisting of gypsum, cement, ground granulated blast-furnace slag, and liquid glass. In an exemplary embodiment of the present disclosure, the first binder is gypsum.

In an embodiment of the present disclosure, the first binder is an inorganic hydraulic binder (lime and silicate based binder).

The inorganic binders can be advantageous over the organic binders as they have a comparatively higher compressive and tensile strength.

In an embodiment of the present disclosure, the second filler is at least one selected from the group consisting of calcium carbonate, magnesium carbonate, silica and clay. In an exemplary embodiment of the present disclosure, the filler is calcium carbonate.

In an embodiment of the present disclosure, the insulating material is at least one selected from the group consisting of phyllosilicate based material, basalt stone fibers and polystyrene granules. In an exemplary embodiment of the present disclosure, the insulating material is phyllosilicate mineral. In an exemplary embodiment of the present disclosure, the coating composition comprises 25.5 mass% of the white pigment paste, 11 mass% of the at least one extender, 1.5 mass% of the at least one water repellent additive, 1.5 mass% of the at least one biocide, 7.5 mass% of the at least one first binder, 7.5 mass% of the at least one second filler and 7.5 mass% of the at least one insulating material, and q.s water; wherein the mass% of each component is with respect of the total mass of the coating composition.

In an embodiment of the present disclosure the coating composition is prepared by the following steps: i. blending predetermined amounts of white pigment paste, at least one extender, at least one water repellent additive, at least one biocide, at least one first binder, at least one second filler, and at least on insulating material for a time period in the range of 5 minutes to 10 minutes to obtain a mixture; and ii. adding a predetermined amount of water to the mixture followed by blending for a time period in the range of 5 minutes to 30 minutes to obtain the coating composition.

The process is described in detail.

Blending predetermined amounts of white pigment paste, at least one extender, at least one water repellent additive, at least one biocide, at least one first binder, at least one filler, and at least on insulating material for a time period in the range of 5 minutes to 10 minutes to obtain a mixture.

In an embodiment of the present disclosure, the predetermined amounts of white pigment paste, at least one extender, at least one water repellent additive, at least one biocide, at least one first binder, at least one filler, and at least on insulating material are blended by using a main mixer.

In an embodiment of the present disclosure, the predetermined amount of white pigment paste is in the range of 15 mass% to 50 mass% with respect of the total mass of the coating composition. In an exemplary embodiment of the present disclosure, the predetermined amount of white pigment paste is 25.5 mass% with respect of the total mass of the coating composition. In an embodiment of the present disclosure, the predetermined amount of at least one extender is in the range of 5 mass% to 15 mass% with respect of the total mass of the coating composition. In an exemplary embodiment of the present disclosure, the predetermined amount of extender is 11 mass% with respect of the total mass of the coating composition.

In an embodiment of the present disclosure, the predetermined amount of at least one water repellent additive is in the range of 0.5 mass% to 5 mass % with respect of the total mass of the coating composition. In an exemplary embodiment of the present disclosure, the predetermined amount of water repellent additive is 1.5 mass% with respect of the total mass of the coating composition.

In an embodiment of the present disclosure, the predetermined amount of at least one biocide is in the range of 0.5 mass% to 5 mass % with respect of the total mass of the coating composition. In an exemplary embodiment of the present disclosure, the predetermined amount of biocide is 1.5 mass% with respect of the total mass of the coating composition.

In an embodiment of the present disclosure, the predetermined amount of at least one first binder is in the range of 5 mass% to 15 mass% with respect of the total mass of the coating composition. In an exemplary embodiment of the present disclosure, the predetermined amount of first binder is 7.5 mass% with respect of the total mass of the coating composition.

In an embodiment of the present disclosure, the predetermined amount of at least one second filler is in the range of 5 mass% to 15 mass% with respect of the total mass of the coating composition. In an exemplary embodiment of the present disclosure, the predetermined amount of second filler is 7.5 mass% with respect of the total mass of the coating composition.

In an embodiment of the present disclosure, the predetermined amount of at least one insulating material is in the range of 5 mass% to 15 mass% with respect of the total mass of the coating composition. In an exemplary embodiment of the present disclosure, the predetermined amount of insulating material is 7.5 mass% with respect of the total mass of the coating composition.

Adding a predetermined amount of a water to the mixture followed by blending for a time period in the range of 5 minutes to 30 minutes to obtain the coating composition. In an exemplary embodiment of the present disclosure, the time period is 20 minutes. In an embodiment of the present disclosure, the cool roof is coated with a binder layer.

In an embodiment of the present disclosure, the binder layer is applied on the cool roof by at least one selected from the group consisting of spray coating, and online spray coating atomizer. In an exemplary embodiment of the present disclosure, the binder layer is applied by online spray coating atomizer.

The binder layer is applied on the coated cool roof to give an additional binding and water- repellent effect to the cool roof.

In an embodiment of the present disclosure, the binder layer comprises a second binder and a third fluid medium.

In an embodiment of the present disclosure, the ratio of the second binder to the third fluid medium is in the range of 1:0.5 to 1:2. In an exemplary embodiment of the present disclosure, the ratio of the second binder to the third fluid medium is 1:1.

In an embodiment of the present disclosure, the binder layer is prepared by mixing the second binder and the third fluid medium in a mass ratio in the range of 1:0.5 to 1:2. In an exemplary embodiment of the present disclosure, the binder layer is prepared by mixing the second binder and the third fluid medium is in a mass ratio of 1:1.

In an embodiment of the present disclosure, the second binder is selected from thermosetting polymers and thermoplastic cross-linkable polymers.

In an embodiment of the present disclosure, the cross-linkable thermoplastic polymer is at least one selected from the group consisting of acrylic resin, epoxy, polyurethane and copolymer. In an exemplary embodiment of the present disclosure, the thermoplastic polymer is water based acrylic resins.

In an embodiment of the present disclosure, the third fluid medium is water.

In an embodiment of the present disclosure, the process of preparing the cool roof further comprises the following steps; i) converting the cool roof into profile sheets to obtain corrugated sheets; ii) placing the corrugated sheets between templates for a second predetermined time period to obtain hardened sheets; and iii) curing the hardened sheets for a third time period to obtain a cured cool roof.

In an embodiment of the present disclosure, the cool roof sheets are converted into profile sheets by using corrugated pads to obtain the corrugated sheets.

In an embodiment of the present disclosure, the cool roof sheets are transferred using a conveyor and then further converted into profile sheet using the corrugators pad to obtain the corrugated sheets.

In an embodiment of the present disclosure, the corrugated sheets are placed between templates for a second predetermined time period to obtain hardened sheets.

In an embodiment of the present disclosure, the second predetermined time period is in the range of 5 hours to 15 hours. In an exemplary embodiment of the present disclosure, the second predetermined time period is 8 hours.

In an exemplary embodiment of the present disclosure, the corrugated sheets are stacked between two templates and kept for 8 hours within the template to complete the initial hardening process to obtain the hardened sheets.

In an embodiment of the present disclosure, the hardened sheets are cured at room temperature for third predetermined time period to obtain the cured cool roof.

In an embodiment of the present disclosure, the third predetermined time period is in the range of 15 days to 30 days. In an exemplary embodiment of the present disclosure, the third predetermined time period is 21 days.

In an exemplary embodiment of the present disclosure, the hardened sheets from the stacks are removed after 21 days from a covered shed to obtain the cured cool roof sheets. The cured cool roof sheets are checked for quality parameters and are ready for dispatch.

The cool roof of the present disclosure is prepared by using a system. The system comprises: i) plurality of sieve cylinders; ii) a rotating metallic drum; iii) plurality of vacuum boxes; iv) an automated spray coating atomizer system; v) a suction box; and vi) a hood.

In an embodiment of the present disclosure, the system comprises the plurality of sieve cylinders in synchronization with each other to form a predetermined number of layers of the premix.

In an embodiment of the present disclosure, the rotating metallic drum is used to receive the formed predetermined number of layers of the premix to form a stack of layers having a predetermined thickness.

In an embodiment of the present disclosure, the plurality of vacuum boxes is used to remove additional water from the roof sheet.

In an embodiment of the present disclosure, an online spray coating atomizer is used for coating the operative top layer of the substrate, a suction box is used to remove the excess water from the stack of layers and a hood to collect the fumes generated during the spray.

The cool roofs of the present disclosure offer both immediate and long term saving in building energy costs. The cool roof comprising the substrate composition along with the coating composition helps in reducing building heat gain as white reflective roof typically increases only 10 °C to 25 °C above the ambient temperature during the day. Moreover, the cool roofs of the present disclosure create savings on summer time air conditioning expenditures. Further, the cool roofs of the present disclosure enhance the life expectancy of both the roof substrate and the buildings cooling equipment. Even further, the cool roofs of the present disclosure, improve thermal efficiency of the insulation. This is because as the temperature increases, the thermal conductivity of the cool roofs insulation also increases. Still further, the cool roof of the present disclosure reduces the demand for electric power by as much as 10 percent, reduces air pollution and greenhouse emission and provides energy savings.

The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.

The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.

EXPERIMENTAL DETAILS

Experiment 1: Preparation of a cool roof in accordance with the present disclosure.

Example 1.1: Preparation of a substrate composition in accordance with the present disclosure.

In accordance with the present disclosure, the substrate can be an asbestos substrate or a non asbestos substrate.

(a) Preparation of Non asbestos substrate composition in accordance with the present disclosure.

20 kg of soft wood kraft pulp (primary pulp), 20 kg of waste packaging material (secondary pulp), 20 kg of PVA fibre (synthetic fiber) was mixed in a mixer for 15 minutes to obtain a first mixture.

Separately, 720 kg of cement, 150 kg of fly ash, 50 kg of ground calcium carbonate (first filler) and 20 kg of kaolin (mineral additive) were mixed in a mixer for 10 minutes to obtain a second mixture.

The so obtained the first mixture and the second mixture were mixed in a mass ratio of 1:10 in a mixer for 4 minutes to obtain an asbestos substrate.

(b) Preparation of asbestos cement substrate composition in accordance with the present disclosure.

20 kg of waste packaging material (secondary pulp) and 50 kg of asbestos fiber and 5 kg of polyester fibres (synthetic fibres) were was mixed in a separate mixer for 15 minutes. Separately, 520 kg of cement, 350 kg of fly ash, 50 kg of ground calcium carbonate (first filler) and 5 kg of wollastinite and calcite (mineral additive) were mixed for 10 minutes to obtain a second mixture.

The so obtained the first mixture and the second mixture were mixed in a mass ratio of 1:10 in a mixer for 4 minutes to obtain an asbestos substrate.

Example 1.2: Preparation of a coating composition in accordance with the present disclosure.

50 kg of lead-based pigment (white pigment) was mixed with 50 kg of water (second fluid medium) (pigment to fluid medium ratio=l: l) in a mixer for 10 minutes to obtain a white pigment paste.

25.5 kg of the so obtained white pigment paste, 11 kg of extender, 1.5 kg of water repellent additive, 1.5 kg of biocide, 7.5 kg of first binder, 7.5 kg of second filler and 7.5 kg of insulating material, were blended in a mixer for 8 minutes to obtain a mixture. To the so obtained mixture, 38 kg of water was added followed by blending for 20 minutes to obtain the coating composition.

Example 1.3: Preparation of the cool roof in accordance with the present disclosure.

The cool roof was prepared by using Hatschek Machine.

30 kg of water was added in 70 kg of the substrate composition (either asbestos substrate composition or non asbestos substrate composition) obtained in Example 1.1 and stirred for 10 minutes to obtain a premix.

6 layers were formed from the so obtained premix by using an endless felt on a plurality of sieve cylinders. The Top layer was coated with online cool roof coating, The so formed 6 layers were transferred and stacked on a rotating metallic drum to form a stack of layers of 6 mm.

From the so formed stack of layers excess water was removed on a moving felt by using a vacuum system followed by further removing the excess water from the stack of layers by squeezing the layer between a forming drum and press roller to form a substrate having an operative top layer. The operative top layer of the substrate was coated with the coating composition obtained in Example 1.2 by an online spray coating atomizer to obtain the cool roof of 6 mm.

Separately, 50 kg of water based acrylic resins (thermoplastic polymer- second binder) was mixed with 50 kg of water to obtain a binder layer composition. The so obtained binder layer composition was sprayed by using an online spray coating atomizer on the coated cool roof to obtain the cool roof sheet.

The so obtained cool roof sheet was further converted into profile sheets by using corrugated pads to obtain corrugated sheets. The corrugated sheets were stacked and placed between templates for 8 hours to obtain hardened sheets. The so obtain hardened were cured at room temperature for 21 days in covered area to obtained cured cool roof.

Experiment 2; Characterization study of the cool roof sheets prepared in accordance with the present disclosure.

The cool roof sheets prepared in accordance with the present disclosure were subjected for the characterization tests. Solar direct reflectance:

The solar direct reflectance test was performed on cool roof sheets (having 6 mm thickness) prepared in accordance with the present disclosure, roof sheet without coating (Comparative example 1), coated asbestos cement roofing sheet with Dr. Fixit roof seal (Comparative example 2) and coated asbestos cement roofing sheet with British Paints Terrace (Comparative example 3). The solar direct reflectance of all the roof sheets was measured by using EN 410:2011 test method. The results are illustrated in Table 1.

Table 1: Solar direct reflectance analysis

The results of Table 1 indicate that the cool roof sheet prepared in accordance with the present disclosure showed good solar reflectance as compared to the roof sheet without any coating (Comparative example 1). Further, the cool roof sheet prepared in accordance with the present disclosure showed comparable solar reflectance with the commercially available cool roof coating compositions (Comparative examples 2 and 3).

> Solar reflectance index (SRI) under different wind conditions:

The solar reflectance index (SRI) is an indicator of the ability of a roof surface to return solar energy to the atmosphere which takes into account both solar reflectance and thermal emissivity of the substrate. The solar reflectance index (SRI) test under different wind conditions was carried out for the cool roof sheets prepared in accordance with the present disclosure and the roof sheets of the comparative examples 1 to 3. The solar reflectance index of the all the roof sheets was determined in accordance with ASTM E 1980-19. The results are illustrated in Table 2.

Table 2: Solar reflectance index (SRI) analysis From Table 2 it is observed that the cool roof sheet prepared in accordance with the present disclosure showed higher SRI under low wind, medium wind and high wind conditions as compared to the roof sheet without coating (Comparative example 1) which means that the cool roof prepared in accordance with the present disclosure is cooler than the roof sheet without coating (Comparative example 1) under the same solar energy exposure. Further, there were no visible cracks, no de-lamination and no other defects which may affect the performance during the use of the cool roof sheet prepared in accordance with the present disclosure. Furthermore, it is observed that the SRI results of the cool roof sheet of the present disclosure are comparable with the commercially available coating compositions (comparative examples 2 to 3). Unlike the coated asbestos cement roofing sheet with Dr Fixit roof seal (Comparative example 2) and coated asbestos cement roofing sheet with British Paints Terrace Master (Comparative example 3), the cool roof prepared in accordance with the present disclosure does not require any pretreatment, therefore the cool roof prepared in accordance with the present disclosure is highly cost effective, less time consuming, economically significant and less laborious. Surface temperature under different wind conditions:

The surface temperature test under different wind conditions was performed for the cool roof sheets prepared in accordance with the present disclosure and the roof sheets of the comparative examples 1 to 3. The wind conditions were low wind, medium wind and high wind. The surface temperatures of all the roof sheets were measured in accordance with EN 673:2011 test method. The results are illustrated in Table 3.

Table 3: Surface temperature analysis From Table 3 it was observed that the cool roof sheet prepared in accordance with the present disclosure showed lesser surface temperature under low wind, medium wind and high wind conditions as compared to the roof sheet without coating which means that the cool roof prepared in accordance with the present disclosure is cooler than roof sheet without coating (Comparative example 1) under the same temperature exposure. Further, it is observed that the surface temperature results of the cool roof sheet of the present disclosure are comparable with the commercially available coating compositions (Comparative examples 2 and 3).

Characteristics of the cool roof sheet after heat rain test:

The heat rain test was carried out on the cool roof sheets of the present disclosure in order to check the resistance of the roof sheets under various climatic conditions. The cool roof sheets of the present disclosure were first subjected to heat rain test. The hot and dry climate zone for the heat rain test was used as per ASTMD7897:2018 and then the cool roof sheet after heat rain test was further subjected to testing of the properties.

The soiling mixture used for soiling and weathering comprised 79% dust, 20 % salts, 0% POM, and 1% soot. This yielded 0.98 g/L dust, 0.25 g/L salts, 0 g/L POM, and 0.012 g/L soot in the soiling mixture. Table 4 shows the solar direct reflectance and the emissivity of the cool roof sheet prepared in accordance with the present disclosure after the heat rain test. Table 5 shows the solar reflectance index (SRI) and the surface temperature of the cool roof sheet prepared in accordance with the present disclosure under different wind conditions.

Table 4: Heat rain test of the cool roof in accordance with the present disclosure

Table 4 illustrates that the cool roof sheet prepared in accordance with the present disclosure showed solar direct reflectance of 0.7658, which indicated that even after heat and rain conditions, the cool roof sheet of the present disclosure showed same solar reflectance as before the heat rain test. Further, there were no visible cracks, no de-lamination and no any other defect which may affect the performance during the use in the cool roof sheet prepared in accordance with the present disclosure even after heat rain test. Table 5: Heat rain test of the cool roof in accordance with the present disclosure under different wind conditions

From Table 5 it was observed that there was no significant change in the values of surface temperature of the cool roof sheet prepared in accordance with the present disclosure after heat rain test under different wind conditions, indicating that the cool roof sheet is resistant to heat and rain conditions. Moreover, it was observed that the cool roof sheet prepared in accordance with the present disclosure showed higher SRI under low wind, medium wind and high wind conditions as compared to the roof sheet without coating (Comparative example 1) which means that the cool roof prepared in accordance with the present disclosure is cooler than roof sheet without coating (Comparative example 1) under the same solar energy exposure even after the heat rain test.

Further, it is observed that the cool roof sheet prepared in accordance with the present disclosure showed lower surface temperature (T _g ) under low wind, medium wind and high wind conditions as compared to the roof sheet without coating (Comparative example 1). Furthermore, the cool roof prepared in accordance with the present disclosure demonstrated good resistance to algae and fungal attack as compared to the roof sheet without coating (Comparative example 1). Performance measurement test:

The performance measurement test of the cool roof sheet prepared in accordance with the present disclosure was carried out. The performance was measured by monitoring various parameters such as indoor air temperature and humidity, inner and outer roof surface temperatures with and without cool roof of the present disclosure. The results of the performance measurement tests are illustrated in Table 6.

Table 6: Performance measurement test From Table 6 it is observed that the room air temperature, room air relative humidity, outside roof surface temperature and inside roof surface temperature of the cool roof prepared in accordance with the present disclosure are lesser than the room air temperature, room air relative humidity, outside roof surface temperature and inside roof surface temperature without the cool roof. It means that the cool roof prepared in accordance with the present disclosure helps to reflect sunlight and heat away, reducing the roof temperatures. Thus, the cool roof prepared in accordance with the present disclosure achieves the greatest cooling savings in hot climates and reduces the peak electricity demand, which can help to prevent power outages. Hence, the cool roof of the present disclosure indicated enhanced performance. Simulation Study:

The cool roof obtained in the experiment 1 was subjected to a simulation study in different cities of India. The different cities and climate are given below in Table 7.

Table 7: Cities and their temperatures

The key findings of the simulation study which includes the city, climate type, parameter assessed and the quantified impact of the cool roof comprising the substrate and the coating composition in accordance with the present disclosure on the parameters are summarized in Table 8.

Table 8: Simulation study analysis |

From Table 8 it was observed that for all cities there was a reduction in peak values for indoor air temperature, indoor operative temperature, outside and inside surface temperatures by using the cool roof comprising the coating composition in accordance with the present disclosure. The key observations were: the impact of coating on indoor air and operative temperature causes the temperature to be lower by minimum 3 °C and maximum of 7°C for every city; the impact of coating on outside surface temperature causes the temperature to be lower by minimum 10°C and maximum of 18°C for every city; indoor air humidity is higher for cases with coating, for Coimbatore and Allahabad. However, negligible difference is observed for remaining cities; the coating does not impact comfortable hours, which were evaluated using the India Model for Adaptive thermal Comfort - natural ventilation band; and the cool roof of the present disclosure comprising the substrate coated with the coating composition are ready to use. Unlike the conventional cool roofs, the cool roof of the present disclosure does not require any pretreatment. Hence, it is efficient, less time consuming, economically significant and less laborious.

TECHNICAL ADVANCES AND ECONOMIC SIGNIFICANCE

The present disclosure described herein above has several technical advantages including, but not limited to, the realization of,

- a cool roof, that

• provides temperature reduction on the roof surface and inside the room;

• has excellent water repellency;

• has antifungal and anti- algal properties; and

• has aesthetic value. and

- a process for preparing the cool roofs that:

• forms a uniform and continuous coating layer on the substrate;

• ensure good adhesion between the coating composition and the substrate; • provides automated application of coating over the substrate and avoids over spraying;

• provides highly effective cool roof that does not require any pretreatment and hence is ready to use;

• is less laborious compared to the commercial cool roofs;

• is simple;

• is eco-friendly; and

• is economical, profitable.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.

While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.