Title of Invention

A METHOD OF MANUFACTURING BAMBOO MAT CORRUGATED SHEETS

Abstract

Investigations were carried out at IPIRTI under a project sponsored by BMTPC to develop an Eco-friendly roofing sheet. since corrugated sheets are more ideal for roofing application, attempts were made to develop bamboo mat corrugated sheet (BMCS). for this purpose platents having approximazted sinusoidal wave patterns were designed to be fitted with hydraulic hot press to produce corrugated sheets by using bamboo mat coated with suitable resin binder. extensive eperiments were carried out using woven bamboo mats of melaconna bambusoides & ochlandra travancorica that were dipped in phenol formaldehyde resin and pressed under temperature and pressure. sheets made in the initial experiments were subjected to rigorous test for evaluating bond integrity. BMCS thus produced were subjected to performance tests like load bearing capacity, water permeability test, reasistence to boiling water and weatherability and found to possess excellent load bearing capacity. BMCS roofing sheets has enhanced characteristics like toughness,resilience and ductility. apart from this BMCs is environment friendly, energy efficient and possesses good fire resistence. the BMCS developed is first of its kind in the country.

Full Text

INTRODUCTION To meet the growing demand of building especially for a roof cladding material, the inventors have developed cost effective, energy efficient and eco-friendly technology for Bamboo Mat Corrugated Sheets. This is based on woven mats from bamboo, a fastest growing plant which can be grown in entire parts of the country and even considered to be suitable under agro-forestry/farm forestry sector. Bamboo Mat Corrugated Sheets (BMCS) exhibits superior mechanical properties (High MOR, MOE and Modulus of Rigidity) with excellent Load Bearing Capacity (LBC), Resilience and Ductility as compared to several corrugated roofing sheets available at present. It also possesses low thermal conductivity, coupled with resistance to moisture, weather, insects and other bio-deteriorating agents like fungi. It also effectively arrests spread of fire. It is superior to other available roofing sheets as it has very high strength to weight ratio and high Specific Load Bearing Capacity (LBC). One of the three basic needs of humans, other than food and clothing is shelter and one expects it should be of low cost and long durability. In a building construction, roof selection is a choice relative to the cost of the building. The roof cladding must be capable of resisting loads to which it is subjected to, and carry them satisfactorily to the supporting structure like walls or other supports and also provide protection from wind, rain and sunlight. In recent years architects have given attention to imaginative use of concrete, (i) asbestos-cement corrugated sheets (ii) galvanized iron corrugated sheets (iii) aluminium corrugated sheets and (iv) fiber glass reinforced plastics corrugated sheets as roofing materials. All such modem roofing materials though provide pleasing architectural effects, needs high energy for manufacturing and are based on non-renewable and non-sustainable supply of raw material. Asbestos cement corrugated sheet dust particles are believed to cause lung cancer. As a result, use of asbestos cement corrugated sheets has been banned in most of the developed countries. The inventors have developed corrugated sheets from woven bamboo mats. Bamboo is a fast growing plant, quick maturing, is one of the strongest naturally growing materials, which can be extensively grown in most of the tropical and sub-tropical region. Split bamboos are utilized in weaving mats. The bamboo mat coated with resin is mechanically corrugated in a specially designed mould under high pressure and temperature. The thickness of the sheets can be varied with the number of mats, thickncss of the slivers and the design of the mould. A number of platen profiles designed and developed were subjected to pilot plant trials for the manufacture of large size sheets and the profile then standardized for the production of sheets suitable for commercial production. The quality and quantity of resin requirement, temperature and pressure for pressing, suitable coating composition and coating techniques were studied extensively and standardized. The strength properties, durability, weatherability were also studied. The Results were found to be satisfactory. Hence, BMCS are ideal for roofing purposes. The trials were made on different species of bamboo like Melacoivia Bambusoides, Ochlandra Travancorica, Dendrocalamus Hemiltonii, Dendrocalamus striclus. The process parameters were studied and optimized for making BMCS. Accordingly it is the primary object of the invention to develop a Bamboo Mat Corrugated Sheets suitable as a roof structure. It is-another object of the invention to develop a Bamboo Mat Corrugated Sheets which possess excellent load bearing capacity. It is another object of the invention to develop a Bamboo Mat Corrugated Sheets which possess resilience and ductility coupled with low thermal conductivity. It is another object of the invention to develop a Bamboo Mat Corrugated Sheets, which is resistant to moisture, weather, insects and other bio-deteriorating agents like fungi. It is another object of the invention to develop a Bamboo Mat Corrugated Sheets, which is resistant to spread of fire. It is another object of the invention to develop a Bamboo Mat Corrugated Sheets which can also be used as a wall, as a container for packaging, sandwich construction, prefabricated houses, curved roofs, flooring and as structural components like stress skin panels, Web beams. Further the object of the invention will be clear from the following specification: Nature of the invention and the manner in which it is to be performed is clearly and fully described in the following specification. The invention is described with reference to drawings which accompany this complete specification. FIGURES Figure 1 : of the drawings shows the entire process flow chart of manufacturing Bamboo Mat Corrugated Sheets. Figure 2 : of the drawings shows the hot press for manufacture of Bamboo Mat Corrugated Sheets. Figure 3 : of the drawings shows the upper die profile and lower die profile according to the invention. Figure 4: of the drawing shows llie finished product Bamboo Mai Corrugnlcd Sheet. DESCRIPTION Figure 1 shows the entire processing flow chart starting from matured green bamboo raw material and subjecting the matured green bamboo to various processes. The sequence in which the raw material is subjected to is clearly shown in the diagram. Woven bamboo mat is the basic raw material. As bamboo grows very rapidly, it can be cultivated for providing quick and continuos return on the investments made. It possesses good mechanical properties and a high strength to weight ratio which can facilitate manufacture of lighter and also stronger structural components for housing. BMCS manufactured using such a material can find extensive use in housing especially in earthquake prone areas, in construction of cost effective houses particularly in quick construction in disaster prone areas. Now Gol is encouraging the farmers to grow bamboo as it can be easily grown even in homesteads and harvested at the time of need without much additional expenditure. Bamboo is split into slivers either manually (suitable for bamboo with longer internode) or by machine (bamboo with shorter internode). The sliver thickness plays an important role as it directly influences mat thickness and quality, which in turn affects the quality of the Bamboo Mat Corrugated Sheets. The slivers are then woven into mats. Herring Bone type of weaving used for making BMCS gives better flexibility and rigidity. An important precaution to be taken in making mats for Bamboo Mat Corrugated Sheets is that the slivers with glossy peripheral (epidermal) and endodemi layer should be avoided, as they are resistant to bonding. Further they are highly siliceous and non- wetting. However epidermal layer can be used for basketry and other handicraft products. The moisture content of woven mats is in the range of 12% - 15%. If transportation and storage time of a month or more is inevitable, it is recommended to give prophylactic treatment to make the mats resistance to borer infestation. The simplest and effective treatment of mats, provided they are not exposed to rain, is spraying with 2%solution of a mixture of boric acid and borax in the ratio of 1:1. Spraying can be done by using a knapsack sprayer. The mats should be air dried after treatment and can be stored for longer a period without infestation by borers. RESIN MANUFACTURING Phenol fomialdehyde resin is used for the manufacture of Bamboo Mat Corrugated Sheets, It is manufactured in a batch reactor. Phenol formaldehyde resin is manufactured by reacting phenol and formaldehyde in the ratio of 1:1.0- 1:3.0 in presence of alkali catalyst in a predefined proportion. Reaction is exothermic. Condensation is done at a temperature of 60°C- 100°C for a period of 30-120 minutes. RESIN PROPERTIES i) Viscosity 40-400 cP at 25°C ii) Water Tolerance 1:5-1:30 at 25°C. iii) Total Dry solid content 10% - 60%. Incorporation of eco-friendly preser\'ative such as sodium octoborate tetrahydrate, Pentachlorophenate and chlorothylonil in the resin formulation to improve resistance to insects and fungi did not have any adverse effect on the bond quality of BMCS. RESIN DILUTION The PF resin with required properties is diluted with eco-friendly solvent in the ratio as claimed. Lesser dilution would result in excess resin consumption. This could cause flow of excess resin out of Bamboo Mat Corrugated Sheets (if moisture is not maintained as claimed) and gives unpleasant appearance. More dilution would affect bonding properties and give unsatisfactory results when subjected to cyclic boil dry tests and water permeability tests. So the dilution ratio is the key parameter. MAT DIPPING Mat dipping is done in a resin applicator. Mats are dipped in diluted resin solution and soaked for about 3-15 minutes. Mats are then lifted and kept in an inclined position for about 10-60 minutes till excess resin stops dripping completely from the mats. STABILIZATION AND DRYING The resin treated mats are stacked and stabilized for 2-12 hrs. After the stabilization period is completed the resin treated mats are dried in a simple dr>'ing chamber or in a band dryer at a temperature of 30 - 120°C (ill the moisture conlcnt is brought down as claimed. Lesser moisture content would lead to poor bonding due to dry out and excess moisture would cause blister formation during hot pressing process. The exterior surface of the resin treated mats are passed through glue spreader and coated with specially formulated phenolic resin adhesive incorporated with additive to impart smooth surface and resistance to UV and weathering. ASSEMBLING AND HOT PRESSING After drying the resin coated mats are assembled on a support caul plate with release film on either side. The thickness of Bamboo Mat Corrugated Sheets depends on the thickness of slivers and number of mats used as well as profile of platens. Depending on the thickness required, a number of mats are assembled and loaded into a hot press fitted with moulded dies of definite profile and design as claimed. The temperature of hot pressing ranges from 120°C - 180°C. The pressure ranges from 5 - 30kg/cm^ and time of hot pressing from 3-15 minutes. Once the cycle of loading, pressing and releasing is completed the Bamboo Mat Corrugated Sheets would be ready for further processing. It is trimmed, coated if required and despatched for use. The processing parameters arc optimized after detailed tests. It is evident tliat Bamboo Mat Corrugated Slieets is a technologically sound product made from renewable natural material viz., bamboo. The product is an eco-friendly and people friendly leading to large employment generation cspccially for rural/tribal people. The Bamboo Mat Corrugated Sheets developed is light, strong, easy to work with simple tools, and easy to transport and handle. SALIENT FEATURES OF THE INVENTION ARE AS FOLLOWS : The design of the corrugated moulding platens is such that they have an approximated sinusoidal profile with a definite pitch to depth ratio to get the desired profile. The thickness of the Bamboo Mat Corrugated Sheets depends on the profile of the moulding dies as well as on the number of mats used for making the Bamboo Mat Corrugated Sheets. The mole ratio of phenol /formaldehyde/alkali catalyst shall be in an ideally worked out proportion. The resin will be diluted with an economic and eco-friendly solvent. The mats are dipped / soaked in resin for the stipulated period depending on the thickness of sliver for making mats. The resin-coated mats are stabilized and dried to predetermine moisture content to make the corrugated sheet. The exterior surface of bamboo mat's are coated with specially formulated adhesive to enhance durability. The dried mats are assembled and loaded into profiled platen dies and hot pressed. The Bamboo Mat Corrugated Sheets so produced is either given preservative treatment or suitable coatings for enhanced durability. The Bamboo Mat Corrugated Sheets can be manufactured in various thickness and profile to meet span and load bearing capacity requirement. The Bamboo Mat Corrugated Sheets thus manufactured possess excellent load bearing capacity, resilience and ductility coupled with low thermal conductivity, resistance to moisture, weather, insects and other bio-deteriorating agents like fungi. It is also resistant to spread of flame. The Bamboo Mat Corrugated Sheets developed besides being used as a roofing material has several other potential uses like Walling, Container/Packaging, Sandwich construction, Pre-fabricated houses, Curved roofs, Flooring and Structural Components like Stress skin panels, Web beams etc. It is to be understood that the basic aspect of the description is to illustrate salient features of the invention. It is to be understood that within the scope of the invention various modifications are permissible. 5. CLAIMS 1. A method of manufacturing Bamboo Mat Corrugated Sheets involving Weaving slivers of bamboo into mats, giving prophylactic treatment to the aforesaid mat, air drying the said mat after giving prophylactic treatment, dipping the mat in a diluted resin solution and soaking for about 3-15 minutes lifting and keeping the mat in inclined position for about 10-60 minutes till excess resin stops dripping completely from the mats, stacking and stabilizing for a period of 2 - 12 hours, drying the mat in a simple drying chamber till moisture content is control as required, assembling and hot-pressing so as to obtain Bamboo Mat Corrugated Sheets, wherein the design of the corrugated moulding platens have approximated sinusoidal profile with a definite pitch to depth ratio to get desired profile. 2. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in Claim 1 where the thickness of the Bamboo Mat Corrugated Sheets depends on the profile of moulding dies as well as number of mats used for making the Bamboo Mat Corrugated Sheets. 3. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein mats with Herring Bone type of weaving give better fiexibility and rigidity. 4. A method of manufacturing Bainboo Mat Corrugated Sheets as claimed in claim 1, wherein Bamboos are split into slivers either manually or by machine. 5. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the moisture content of the woven mats is in the range of 12% to 15%. 6. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the simplest and most effective treatment of mats is by spraying with 2% solution of a mixture of boric acid and borax in the ratio of 1:1. 7. A method of manufacturing Bamboo Mat Corrugated Sheets as claimcd in claim 6 wherein the spraying is done with a knapsack sprayer. 8. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 where Phenol formaldehyde resin is used for bonding the Bamboo Mat Corrugated Sheets. 9. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 8 wherein the said phenol formaldehyde resin is manufactured in a batch reactor. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 8 wherein the phenol formaldehyde resin is manufactured by reacting phenol and formaldehyde in the ratio of 1:1:0 - 1:3:0 in the presence of an alkali catalyst. 11. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the resin has viscosity 40-400 cp at 25 " C and possess water tolerance 1:5 - 1:30 at 25°C and total dry solid content being 10% - 60%. 12. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the resin dilution is a key parameter in the manufacture of Bamboo mat Corrugated Sheets. 13. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein mat dipping is done in a resin applicator. 14. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the mole ratio of phenol/ formaldehyde/ alkali catalyst should be in an ideally worked out proportion. 15. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the number of mats pressed depends on the thickness of the slivers as well as profile of the platens. 16. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the temperature during the hot pressing ranges from 120'C - 180"C and time of hot pressing 3- 15 minutes. 17. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the pressure ranges from 5-30 Kg/cm2 and time of hot pressing 3-15 minutes. 18. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the Bamboo Mat Corrugated Sheets are trimmed coated if required and despatched for use. 19. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the resin will be diluted with an economic and eco-friendly solvent. 20. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the mats are dipped / soaked in resin for stipulated period depending on the thickness of sliver for making mats. 21. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the resin-coated mats are stabilized and dried to predetermine moisture content to make the corrugated sheet. 22. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the exterior surface of bamboo mats are coated with specially formulated adhesive to enhance durability. 23. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the dried mats arc assembled and loaded into profiled platen dies and hot pressed. 24. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the Bamboo Mat Corrugated Sheets so produced are either given preservative treatment or suitable coatings for enhanced durability. 25. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the Bamboo Mat Corrugated Sheets can be manufactured in various thickness and profiles to meet span and load bearing capacity requirements. 26. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein Bamboo Mat Corrugated Sheets thus manufactured possess excellent load bearing capacity, resilience and ductility coupled with low thermal conductivity, resistance to moisture, weather, insects and other bio-deteriorating agents like fungi and fire. 27. A method of manufacturing Bamboo Mat Corrugated Sheets as claimed in claim 1 wherein the Bamboo Mat Corrugated Sheets besides being used as a roofing material have several other potential uses like walling, container/packaging, sandwich construction, prefabricated houses, cun'ed roof flooring and structural components like stress skin panels and web beams. 28. A method of manufacturing Bamboo Mat Corrugated Sheets as described in the complete specification and as illustrated by way of drawings accompanying the complete specification.

Documents:

1172-CHE-2008 AMENDED CLAIMS 16-02-2015.pdf

1172-CHE-2008 AMENDED PAGES OF SPECIFICATION. 16-02-2015.pdf

1172-CHE-2008 CORRESPONDENCE OTHERS 16-02-2015.pdf

1172-CHE-2008 EXAMINATION REPORT REPLY RECEIVED 05-12-2014.pdf

1172-CHE-2008 FORM-1 05-12-2014.pdf

1172-CHE-2008 FORM-1 16-02-2015.pdf

1172-CHE-2008 FORM-3 05-12-2014.pdf

1172-CHE-2008 FORM-3 16-02-2015.pdf

1172-CHE-2008 FORM-5 05-12-2014.pdf

1172-CHE-2008 FORM-5 16-02-2015.pdf

1172-CHE-2008 ABSTRACT.pdf

1172-CHE-2008 AMENDED CLAIMS 05-12-2014.pdf

1172-CHE-2008 AMENDED PAGES OF SPECIFICATION 05-12-2014.pdf

1172-CHE-2008 CLAIMS.pdf

1172-CHE-2008 CORRESPONDENCE PO.pdf

1172-CHE-2008 DESCRIPTION (COMPLETE).pdf

1172-CHE-2008 DRAWINGS.pdf

1172-CHE-2008 FORM-1.pdf

1172-CHE-2008 FORM-18.pdf

1172-CHE-2008 FORM-9.pdf