FORM 2
THE PATENTS ACT 1970
(39 of 1970)
AND
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rulel3)
1. TITLE OF THE INVENTION:
"MANUFACTURING OF FIBER CEMENT ANTI-FUNGAL & ANTI-ALGAL
ROOFING SHEETS"
2. APPLICANT:
(a) NAME: EVEREST INDUSTRIES LIMITED
(b)NATIONALITY: Company incorporated under the Indian Companies Act, 1913 and an existing company under the Companies Act, 1956
(c) ADDRESS: Gat 152, Lakhmapur Village, Dindori Taluka,
Post Bag No.5, District Nashik -422202, Maharashtra, India.
3. PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the invention and the manner in which it is to be formed.

FIELD OF INVENTION:
The present invention relates inbuilt Anti-Fungal & Anti-Algae asbestos and non-asbestos roofing sheets produced by Hatcbeck process. More particularly, the Anti-Fungal & Anti-Algal roofing sheet are prepared by incorporation of suitable biocide additive formulation during the manufacturing, instead of any coating or surface treatment.
BACKGROUND & PRIOR ART:
Fiber cement roofing sheets, made up of either asbestos or non-asbestos, are prone for fungal and algae attack when exposed to external environment. These roofing sheets are highly porous in nature and absorb high water due to contents of raw material like cellulose and asbestos. All these conditions are favorable for any fungus and algae to develop and grow easily. Fiber cement roofing sheets being cheaper and commodity product people often live with these problems.
When sheets are exposed to rain and sunlight, within one or two monsoon they are attacked by heavy fungus and algae. As a result, the roof becomes black and eventually looses its aesthetics. Apart from bad aesthetic, live fungus and algae may create health related problem to human life and may also spoil environment.
The aforementioned problems are often taken care by application of the suitable surface coating either by paint or sealer/primer etc. Various paints and coating with biocides are available in the market to resist the formation of fungus and algae. One such technology has been disclosed in WO2002032830 wherein reinforced cementitious materials are treated with biocides. However, application of the coating on roof sheets has proven to be laborious and costly matter.
Additionally, the volume for the roofing sheets produced by the Indian manufacturer is so high that it becomes practically impossible for them to give coated product to offer anti fungal - anti algae product/solution in the market.
The inventors of the present invention have attempted to overcome the aforementioned problems by incorporating the biocide additives in the building materials during

manufacturing of the roofing sheets, instead of coating or surface treatment of biocide additives as seen from the State of the Art.
SUMMARY OF INVENTION:
According to the present invention, a fiber cement roofing sheet with in-built anti-fungal and anti-algal biocide additives; wherein biocide additives are incorporated into said fiber cement roofing sheet during manufacturing by Hatschek process to enhance the durability and resistance to wide range of fungi and algae.
In an embodiment, the biocide additives are incorporated on top layer of the fiber cement roofing sheet during the manufacturing by Hatschek process. Alternately, the biocide additives are also incorporated in an entire formulation during the manufacturing by Hatschek process. Both of biocide additive addition methods are effective and results into very good anti-fungal anti algae roof sheets. The biocide additive is dry film preservative which helps in resisting development and growth of fungus and algae.
In an another embodiment, the biocide additives used in the fiber cement roofing sheet, according to the invention, are in encapsulated form to enhance the durability and resistance to wide range of fungi and algae.
DETAILED DESCRIPTION:
The present invention discloses a fiber cement roofing sheet with in-built anti-fungal and anti-algal biocide additives; where biocide additives are incorporated into the fiber cement roofing sheet during manufacturing by Hatschek process to enhance the durability and resistance to wide range of fungi and algae.
The fiber cement roofing sheets are manufactured by Hatschek process i.e. layer on layer formation method, which is known in the prior art. In a preferred embodiment of the present invention, the biocide additives are incorporated into the fiber cement roofing sheet during manufacturing as a top layer.

In a preferred embodiment, the biocide additive are selected from Zinc-pyrithione, Idopropynyl butyl carbamet (IPBC), Carbendazim, Diuron, Octyl Iso Thiazolin (OIT) based biocides or a mixture thereof. These biocide additives may be encapsulated to enhance the durability and resistance to wide range of fungi and algae.
Alternately, the biocide additives are incorporated into the entire formulation of fiber cement roofing sheet during the manufacturing by the Hatschek process.
In another embodiment, a process of preparation of a fiber cement roofing sheet with inbuilt anti-fungal and anti-algal properties is disclosed. In the process, the biocide additives are incorporated into the fiber cement roofing sheet during manufacturing by Hatschek process to enhance the durability and resistance to wide range of fungi and algae.
The biocide additive can be incorporated by two methods:
1. Surface incorporation:
In this process the biocide is added in the process so that only the top layer will have maximum effect of this mix. This is achieved by adding the biocides in the last vat of the machine. This step reduces the consumption of biocides by 1/61 of the total requirement as compared to addition in the main mixer directly. A separate arrangement has made to feed the biocides into vat.
The fungus and algal development occurs on portion which gets exposed to rain 8c sunlight. Top surface of the roof is mainly attacked by fungi and algae. Protecting the top surface is the best and economical option. Hatcheck process produces the product by layer on layer formation. Top layer surface is formed by the last vat where the addition of the biocide additive takes place. This method has advantages, such as, incorporation of active biocide additive only on the top surface, less requirement of the biocide additive, reduced contact time of biocide additive with other highly alkaline material like cement and cost effectiveness. This method is very effective with proper vigilant and helps in optimizing the biocide additive requirement. This

requires some modification on the machine to dose the correct quantity of the biocide additive and mixing with other raw material in last vat.
2. Mass incorporation:
In mass incorporation method, the biocides are added in the main mixer. The known quantity of material is added in the main mixer after adding all the raw materials and before being transferred to vats through the agitator and premixer.
The biocide additive is mixed with entire formulation. Biocide additive is chosen in such a way that it has very good dispersion characteristics with high resistance to the alkalinity and non-leachable in nature. This method ensures presence of the active biocide additive in entire mix. All the surface area and including edges have very good desired anti-fungal and anti-algal resistance. This method has some limitation like needs more quantum of biocide to make entire sheet effective and thus costlier but ensures very good resistance to fungus and algae.
The sheets produced by above both the method and biocide additive exposed to natural weathering at various high rainfall areas. These exposed sheets have passed three monsoons and indicated no fungi and algae development on sheets, while control without biocide additive have shown heavy fungus and algae formation on surface and become complete black color.
Accelerated laboratory tests also indicate similar behavior. Both the variants have shown very good anti algal and anti fungal resistance while control without biocide additive is catching fungus and algae rapidly. Laboratory simulated test indicate the durability of this properties more than 7-8 years.
This indicates the fungal and algal resistance of the asbestos and non-asbestos fiber cements roofing sheets is very good when biocide additive is incorporated in mix or top
layer.
The scope of the present invention should not be limited to the preferred embodiment but should be defined by the claims.

WE CLAIM,
1. A fiber cement roofing sheet with in-built anti-fungal and anti-algal biocide additives; wherein biocide additives are incorporated into said fiber cement roofing sheet during manufacturing by Hatschek process to enhance the durability and resistance to wide range of fungi and algae.
2. The fiber cement roofing sheet according to claim 1; wherein said biocide additives are selected from Zinc-pyrithione, Idopropynyl butyl carbamet (IPBC), Carbendazim, Diuron, Octyl Iso Thiazolin (OIT) or a mixture thereof.
3. The fiber cement roofing sheet according to claim 2; wherein said biocide additives are at 0.02-1.5% by solid.
4. The fiber cement roofing sheet according to claim 1; wherein said biocide additives are in encapsulated form.
5. The fiber cement roofing sheet according to claim 1; wherein said biocide additives are incorporated in entire formulation or in top layer.
6. The fiber cement roofing sheet according to claim 1; wherein said biocide additives are incorporated as surface incorporation.
7. The fiber cement roofing sheet according to claim 5; wherein said surface incorporation includes incorporation of said biocide additives on top layer.
8. The fiber cement roofing sheet according to claim 1; wherein biocide additives are incorporated as mass incorporation.
9. The fiber cement roofing sheet according to claim 6; wherein said mass incorporation includes mixing said biocide additives with entire formulation of said fiber cement building material.

10. A process of preparation of a fiber cement roofing sheet with in-built anti-fungal and anti-algal properties; wherein said biocide additives are incorporated into said fiber cement roofing sheet during manufacturing by Hatschek process to enhance the durability and resistance to wide range of fungal and algae.
11. The process of preparation according to claim 10; wherein said biocide additives are selected from Zinc-pyrithione, Idopropynyl butyl carbamet (IPBC), Carbendazim, Diuron, Octyl Iso Thiazolin (OIT) or a mixture thereof.
12. The process of preparation according to claim 2; wherein said biocide additives are at 0.02-1.5% by solid.