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:
"COLOURED FIBER CEMENT ROOFING SHEETS WITH ANIT-ALGAL, ANIT-FUNGAL AND WATER REPELLENT PROPERTIES AND PROCESS
THEREOF"
2. APPLICANT:
(a) NAME: EVEREST INDUSTRIES LIMITED
(b)NATIONALITY: Indian Company incorporated 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 describes the nature of this invention and the manner in which it is to be performed:

RELATED APPLICATION:
This application is an improvement in or modification (Patent to addition) of the Patent Application number 33/MUM/2013, filed on January 04, 2013.
FIELD OF INVENTION:
The present invention relates to a production of coloured fiber cement roofing sheets having anti-fungal, anti-algal properties as well as water repellency. More particularly, the present invention relates to production of a fibre cement roofing sheets by using the process of inbuilt top layer mass pigmentation.
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.
Similarly, to enhance the aesthetics of the roof, the colour coating is the known technology being followed. Documents such as US2307733, US3384924, and US7998571 etc. reveal process/technique of colouring such roofings. However painting is a costly and also is less durable when sheets are exposed to heat / rain environment. The mass pigmentation in last vat is the cheapest option of producing sheets with colour. The. sheets are produced with additional features of aesthetic with different colours and also with antifungus and water repellent properties.
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. The product furnished by the present invention has three features: 1) Coloured for aesthetics by using mass pigmentation 2) Water repellent 3) Antifungus - resistance to algae and fungus.
SUMMARY OF INVENTION:
The present invention discloses a fibre cement roofing sheet with in-built anti-fungal and anti-algal biocide additives, colour pigmentation additives and water repellent additives; wherein said biocide additives, colour pigmentation additives and water repellent additives are incorporated into said fibre cement roofing sheet during manufacturing by mass pigmentation Hatschek process to enhance the durability and resistance to wide range of fungi and algae and to enhance aesthetics and water repellency of the product, respectively.
In an embodiment, the biocide additives are incorporated on top layer of the fibre cement roofing sheet during the manufacturing by Hatschek process.

Along with biocides, the desired colour pigments are also added in the mix of last vat to get the desired aesthetic look on the sheets. A separate preparation tank has been provided for preparing the material with antifungus, colour pigment and water repellent additive. Along with these three components white cement and calcite are also used to enhance the brightness of the colour and also to improve the binding of pigment.
In an another embodiment, the biocide additives used in the fibre cement roofing sheet, according to the invention, are in encapsulated form to enhance the durability and resistance to wide range of fungi and algae. Thus, aforementioned "three in one combination" gives all desired benefits to the product like aesthetics, water repellency and antifungus properties.
DETAILED DESCRIPTION:
The present invention discloses a fibre cement roofing sheet with in-built anti-fungal and anti-algal biocide additives, colour pigmentation additives and water repellent additives; wherein said biocide additives, colour pigmentation additives and water repellent additives are incorporated into said fibre cement roofing sheet during manufacturing by Hatschek process to enhance the durability and resistance to wide range of fungi and algae and to enhance aesthetics and water repellency of the product, respectively.
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, water repellent additive and colour pigments 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. The colour pigments are from various colour oxides specially ground for the desired requirement at in-house facility and which are resistant to alkaline environments. The water repellent additive is a derivatives of silicone based product. The composition of the fiber cement

roofing sheet, according to the present invention, consists of the biocide additives at 0.02-3% by solid, the colour pigmentation additives are added from 5-20% in the mix, and the water repellent additives are added from 0.05-5%. The derivatives of silicon are used in a mix to impart water resistance to the sheets. The mix includes 50-70% white cement, 20-40% calcite to enhance the brightness of the colour as well as to act as binder and Wollastonite as a fibrous material from 5 to 20%. The entire slurry is prepared in a separate tank. Such prepared slurry is transferred to another holding tank. From holding tank the slurry is fed to a last vat along with the normal slurry of fibre cement at 50:50 ratio.
The present invention also discloses a process of preparation of a fibre cement roofing sheets of mass pigmentation with in-built anti-fungal and anti-algal biocide additives, colour pigmentation additives and water repellent additives. The additives are incorporated into the fibre cement roofing sheet during manufacturing by Hatschek process by adding the mix of additives in the last vat of the machine to enhance the durability and resistance to wide range of fungal and algae.
In the process, the biocide additives are incorporated into the fibre cement roofing sheet during manufacturing by Hatschek process to enhance the durability and resistance to wide range of fungi and algae and colour pigmentation brings aesthetics to the product and water repellent additives adds an additional feature of reduced water absorption making product water repellent.
The additives are added in the following method:
In this process all the above three additives are added in the process so that only the top layer will have maximum effect of this mix. This has been achieved by adding the mix of additives in the last vat of the machine. By doing this, the consumption of all these three raw materials is reduced by l/6th of the total requirement as compared to addition in the main mixer directly. A separate arrangement has been made to feed the additives along with binders into vat.

The fungus and algal development occurs on portion which gets exposed to rain and 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 several advantages, For example, incorporation of active biocide additive only on the top surface requires less amount of the biocide additive. It also reduces contact time of biocide additive with other highly alkaline material like cement and cost effectiveness. Similarly use of colour pigmentation in the last vat will bring the aesthetics to roof and also by using colour in the last vat results into cost effective solution. Adding water repellent additive in the system reduces the water absorption of the sheet and also enhances the water repellency of the product. This method is very effective and optimizes the requirement of additives.
Dosing equipment with variable flow control value which is linked to PLC module is required to installed for the consistency in the quality output. This arrangement ensures regulated supply of the mix to the filtration cylinder for uniformity.
Water repellency as well as colour pigmentation are of added advantage for beneficial use of the product. Use of water repellent totally eliminates the seepage problems in the roof and also eliminates even wetness in the sheets. The colour brings an aesthetic look to roofing and makes elegant look.
The test results carried out on the product of the present invention have shown that it is highly weather resistant even in high rainfall areas. There has been no indication of development of fungi as well as algae on the product of the present invention.
Accelerated laboratory tests have also indicated similar behavior. No effect on colours after 50 cycles of heat / rain. No significant change in mechanical properties due to these additives. However product has shown excellent resistance to algae and fungus.
Following accelerated weathering test have conducted on this product.
1. Heat Rain test: Samples are exposed to 50 cycles of Heat/Rain cycle (one cycle is 2hr 50 min water spray followed by 10 min Pause and then 2hrs 50 min radiant

hear 60 deg±5 deg). There are no visible cracks, no de-lamination and no any other defect which may affect the performance in use.
2. Warm Water: Samples were immersed in Hot water 60±5 deg for 56 days and found no deterioration in the strength above 15%.
3. Soak Dry: Samples were exposed to 25 cycles of soak-dry (One cycle - 18 hrs immersion in ambient water followed by 6hrs drying in oven with Temp 60±5deg). There is no deterioration in the strength above 15%.
4. Frost Resistance: Samples were exposed to 50 cycles of the Freezr-Thaw cycle (One^cycle is immersion in ambient water for 18 hrs followed by cooling at -20 deg for 2 hrs). There are no visible cracks, no de-lamination or any defect observed.
5. Product when exposed to natural weathering during rain season has indicated good resistance to fungal and algae attack as compared to the normal product.
Passing of all above test confirms the weathering behavior of the sheets and durability for long use.
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 fibre cement roofing sheet with in-built anti-fungal and anti-algal biocide additives, colour pigmentation additives and water repellent additives; wherein said biocide additives, colour pigmentation additives and water repellent additives are incorporated into said fibre cement roofing sheet during manufacturing by mass pigmentation. Hatschek process to enhance the durability and resistance to wide range of fungi and algae and to enhance aesthetics and water repellency of the product, respectively.
2. The fibre cement roofing sheet according to claim I; wherein said biocide additives are at 0.02-3% by solid, said colour pigmentation additives are added from 5-20% in the mix, and said water repellent additives are added from 0.05-5%.
3. The fibre cement roofing sheet according to claim 1; wherein said biocide additives are selected from Zinc-pyrithione, Idopropynyl butyl carbamet (IPBC), Carbendazim, Diuron, Octyl lso Thiazolin (OIT) or a mixture thereof.
4. The fibre cement roofing sheet according to claim 1; wherein said Colour pigmentations are selected from colour oxides, organic/inorganic colouring ingredients.
5. The fibre cement roofing sheet according to claim 1; wherein derivatives of silicon are used in a mix to impart water resistance to the sheets.
6. The fibre cement roofing sheet according to claim 5; wherein said mix comprises 50-70% white cement, 20-40% calcite to enhance the brightness of the colour as well as to act as binder and Wollastonite as a fibrous material from 5 to 20%.
7. The fibre cement roofing sheet according to claim 1; wherein said biocide additives are in encapsulated form.

8. The fibre cement roofing sheet according to claim 1; wherein said Colour pigments are used in the fine ground form mixed in water and formed into slurry along with other additives.
9. The fibre cement roofing sheet according to claim 1; wherein said additives are incorporated in top layer.
10. The fibre cement roofing sheet according to claim 1; wherein said biocide additives are incorporated as surface incorporation.
11. The fibre cement roofing sheet according to claim 5; wherein said surface incorporation includes incorporation of said additives on top layer.
12. The fibre cement roofing sheet according to claim 1; wherein all additives are incorporated as mass incorporation.
13. The fibre cement roofing sheet according to claim 11; wherein said mass incorporation includes mixing said additives with entire formulation in a separate mixing tank and added along with normal mix of said fibre cement roofing sheets formulation.
14. A process of preparation of a fibre cement roofing sheets of mass pigmentation with in-built anti-fungal and anti-algal biocide additives, colour pigmentation additives and water repellent additives; wherein said additives are incorporated into said fibre cement roofing sheet during manufacturing by Hatschek process by adding said additives in the last vat of the machine to enhance the durability and resistance to wide range of fungal and algae.
15. The process of preparation according to claim 14; wherein said biocide additives are at 0.02-3% by solid, said Colour ingredient pigmentation additives is from 1 to 25% and said water repellent additives from 0.05% to 5%

16. The process of preparation according to claim 14; wherein said biocide additives are selected from Zinc-pyrtthione, Idopropynyl butyl carbamet (IPBC), Carbendazim, Diuron, Octyl Iso Thiazolin (OIT) or a mixture thereof.
17. The process of preparation according to claim 14; wherein said water repellent additives are derivatives of silicon and colour pigments are from selective inorganic colour oxides.
18. The process of preparation according to claim 14; wherein said mix comprising additive 50-70% of white cement and 20-40% of calcite are added to enhance the brightness of the paint and also to act as binder and Wollastonite as a fibrous material from 5 to 20%.