Title of Invention

A PROCESS FOR PREPARATION OF COIR COMPOSITE BOARD

Abstract

ABSTRACT This invention relates to a process for preparation of coir composite board comprising preparation of resin followed by impregnating coir felt sheets with resin thus prepared, curing in atmosphere for 15-20 minutes, drying of resin impregnated sheet at 100°C, and hydraulic pressing at 150 to 170°C wherein the resin is prepared by reacting pre¬heated at 30-40°C aqueous solution of phenol crystals with formalin in the ratio of 1:1.3 to 1:1.15 at elevated temperature of 50-70°C using an alkaline catalyst such as sodium hydroxide.

Full Text

FTELD OF rWENTTON This invention relates to a process for preparation of coir composite board for packaging applications such as for fabrication of pallets, sheathing of wooden crates, and closure for fibre drums. PRIOR ART Commercial and marine plywood are predominantly used in sheathing of heavy crates and in fabrication of wooden pellets and in closure of fibre drums, which are generally used in packaging of chemicals, pharmaceuticals and various powdere, granules and semi-solids. Large quantity of wood is used every year for these packaging applications, which is a drain on our depleting forest resources. Coir, which is the fibrous material of Coconut (Cocos micifera) is known in the art to be used for manufacturing various articles such as carpets, mattresses, etc. including fibre boards (co-pending patent application No,267/MAS/95) and matting board (co-pending patent application No.268/MAS/95). However, no process is reported wherein coir is used in manufecturing coir board, using partial delignification of coir fibre to utilize its lignin(complex phenol content) in forming coir composite board. OBJECTS OF PRESENT EVVENTION An object of the present invention is to propose a process for preparation of coir composite board for packaging applications. Another object of the present invention is to propose a process for preparation of coir composite board as a cost-effective substitute to traditional packaging materials such as commercial and marine plywood. Still another object of the present invention is to propose a process for preparation of coir composite board wherein a novel resin is proposed which is stable with a shelf life of about 6 months as compared to the existing resins which have a tendency to form a jelly within a week after exposure to atmosphere. Yet another object of the present invention is to propose a process for preparation of coir composite board which by partial delignification of the coir fibre using an alkaline catalyst, utilizes the ligninf complex phenol) of the coir fibre to reduce the ratio of phenol to formalin fi-om 1:1 presently used in known art to about 1:1.3 to 1:1.5. Further object of the present invention is to propose a process for preparation of coir composite board wherein a novel resin is proposed which has 2500% water mixibility and therefore can be used after dilution with 5- 15% of solid contents Yet further object of the present invention is to propose a process for preparation of coir composite board, which has excellent conversion properties necessary for fabricating boxes and components for packaging applications. It can be cut, sawed, drilled, screwed and nailed. Still further object of the present invention is to propose a process for preparation of coir composite board, which is freight friendly as it has higher specific strength as compared to the traditional materials of equal thickness and therefore reduces both weight and volume of the pack. Even further object of the present invention is to propose a process for preparation of coir composite board, which can be laminated during/after the process of manufacture and can take prints. Yet further object of the present invention is to propose a process for preparation of coir composite board, which is fungus/insects/termite proof. Still further object of the present invention is to propose a process, which provides coir composite board, which has boiling water resistance. Yet further object of the present invention is to propose a process, which provides coir composite board, which has excellent environment endurance. STATEMENT OF INVENTION According to this invention there is provided a process for preparation of coir composite board comprising preparation of resin followed by impregnating coir felt sheets with resin thus prepared, curing in atmosphere for 15-20 minutes, drying of resin impregnated sheet at 100°C, and hydraulic pressing at 150 to 170C wherein the resin is prepared by reacting pre-heated at 30-400C aqueous solution of phenol crystals with formalin in the ratio of 1:1.3 to 1:1,15 at elevated temperature of SO-TO^C using an alkaline catalyst such as sodium hydroxide. According to this invention, a process is proposed to provide coir composite board, which is a cost-effective and a very prospective substitute to commercial and marine plywood presently used predominantly for packaging applications. The packaging board provided by the process of this invention, Is based on coir fibre, which is the fibrous material surrounding the core kemal of coconut fruit, and is natural abundant by-product of agriculture sector. Coir is mainly being used for producing products like coir mattresses, carpets, etc. Every year, about one lakh trees can be conserved if the coir board as provided by this invention, is commercialized as substitute to wood for packaging in the form of wooden pellets, crate sheathing and closures to fibre drums used for packaging pharmaceuticals, etc. India is the largest producer of coir. Coir is also one of the strongest natural fibre with highest lignin content and is relatively cheaper as compared to other natural fibres such as jute, ramie, banana, pine apple, sisal, aracanut, etc. The process of the invention involves mixing of pre-heated aqueous solution of phenol with formalin and stirring the mixture in a reactor in the presence of an alkaline catalyst preferably sodium hydroxide. The mixture is slowly stirred along with slow heating to raise the temperature around eCC. The resin thus prepared has very high mixibility with water and the resin can therefore, be diluted with water as required. The resin so obtained is stable with a shelf life of around 6 to 7 months. The resin thus prepared is taken in a tank The coir in the form of felt, which has been cut into small pieces, is added to this tank containing resin, which is diluted with water to obtain 15% solid contents- The coir sheets soaked in resin are cured in atmosphere followed by drying at around lOO'^C. The sheets of felt thus impregnated with resin are pressed in a hydraulic press to produce the coir board. The coir board provided by this invention, has excellent boiling water resistance, flexural and comparable strength as compared to commercial plywood is shown in Table-I. The board is insect/termite proof and qualifies the flammability test as per IS: 1734 The board thus prepared has all the features necessary for packaging applications i.e. it can be cut, sawed, drilled, screwed and nailed. As against 8 to 12mm thickness commercial plywood or 25mm soft planks generally used for sheathing for heavy wooden crates, coir composite board due to their higher rigidity, can be used in lower thickness of 6mm or 8mm, for the same purpose. Similarly,as against 12mm thickness marine plywood, 8mm coir composite board of this invention can be used for fabrication of a reusable box with pallet base, for packaging of automobile parts. Also, as against 8mm commercial plywood, only 6mm coir board of this invention can be used as closure to fibre drums, used for packaging of pharmaceuticals, etc. By using dye fixed to hydraulic press, moulded pallets can be produced. Pallet decks of thickness 6mm capable of carrying the load of 1.5 tonnes can be produced using the coir composite board of this invention. DESCRIPTION OF FIGURES The accompanying figures show three different forms of packaging applications based on coir composite board provided by the present invention. These packaging forms are shown for purposes or illustrations and are not intended to imply any limitations on the scope of invention and the applications thereof The coir composite board provided by this invention can be used in other forms/ applications. In the accompanying figures:- Fig, 1: shows use of coir composite board as sheathing for heavy wooden crates; Fig 2: shows the use of coir composite board for fabrication of reusable box. Fig.3: shows the use of coir composite board for fabrication of closures to fibre drums DESCRIPTION OF PROCESS According to this invention, the coir composite board is prepared by the process comprising the following steps: (a) Preparation of Resin Phenol in the form of crystals is mixed with water to form an aqueous solution, tailing preferably 90% crystals and 10% water by weight. The aqueous solution of phenol is mixed in a reactor by continuous stirring. The temperature of the mixture is slowly raised to around 35° C- To this pre-heated aqueous solution of phenol, liquid formalin is added in quantity so that ratio by weight of phenol to formalin is in the range from 1:1.3 to 1:1 5. To this mixture, alkaline catalyst preferably sodium hydroxide in quantity 5% by weight of phenol is added. This alkaline catalyst later when coir fibre is added, brings about partial delignification of the coir fibre to extract lignin(complex phenol) from the fibre, without affecting the specific strength of the fibre. The lignin thus extracted fi-om the fibre, supplements the phenol added to the mixture. It is because of this partial delignification of coir fibre, that quantity of phenol required is in the afore-said range of 1:1.3 to 1:1 5 as against the phenol to formalin ratio of 1:1 presently used in the known art. The mixture is continuously stirred and slowly heated to raise the temperature in the range of 50 to VO^C, preferably 60°C. Continuous water cooling system was used in the reaction and the reaction was allowed to proceed for a duration around 1 to 3 hours preferably around for one and half hour. The resin thus prepared has excellent ivater mixibility and is stable for a period of 6 to 7 months. It has pH value of 9, solid contents around 55% and viscosity Ford B cup of 15-20 sec(100 to 200cp) at around 25'C fb) Preparation of Coir Composite Board The resin as obtained above is taken in a tank. The resin being mixible with water is diluted with water so as to obtain 15% solid contents. Coir, in the form of feh, having preferably grammage( weight of felt sheet in gm/m^) of 100, is cut in small sizes of 8"X 4" and dipped in the tank containing the above diluted resin The coir felt pieces are allowed to remain dipped in the resin for a preferred duration of 10 to 15 minutes. The sheets soaked in resin are cured in atmosphere for about 10-15 imnutes followed by draining for about the same period. The sheets thus obtained are transferred to a drying chamber maintained at around lOO^C. The drying of the sheets in the drying chamber is carried out for a preferred duration of about 15 to 20 minutes. The sheets of feh thus impregnated with resin, are pressed in a hydraulic press with a working pressure between 10 to 30kg/cm^ at a temperature around 150 to 170°C preferably around 160'C. The hot cured boards thus obtained are trimmed wnth a trimmer machine The surface finish is improved as required by spraying melamine or polyurethane. Based on coir composite board obtained by the invention, different forms of packaging based on different thicknesses of coir board, can be prepared such as 6mm or 8nim sheathing for heavy wooden pallets, 6mm thick coir board as closure to bibre drums, 8mm coir composite board for fabrication of reusable/returnable boxes. WORKING EXAMPLE The invention will now be illustrated with working examples. It is to be understood that these examples are intended to illustrate the working of the invention and are not intended to be taken restrictively to imply any limitation on the scope of the invention. EXAMPLE 90kg of phenol were mixed with 10 liters of water in a reactor with stirring and slow heating to SST. To this, 135 liters of formalin was added followed by 4.5kg of sodium hydroxide. The mixture was stirred and slowly heated to 60'C and reaction was allowed for 1 '/; hour with continuous cooling. The coir fibre was separately formed into feh sheet and was dipped in resin thus prepared . The sheets were calendered suitably and cut to required sizes, cured in atmosphere for 10 minutes and dried in a drying chamber for 15 minutes, at a temperature of 150'*C. The sheets thus impregnated with resin were pressed in hydraulic press at a pressure of 30 kg/cm^ . The con- composite boards thus obtained were trimmed by trimming machine. The comparative properties of coir composite board as compared to commercial plywood, are tabulated below in Table-T: It is to be understood that the invention of the present invention is susceptible to modifications, adaptations, and changes by those skilled in art. Such variant embodiments incorporating the features and concepts of the present invention are intended to be within the scope of the present invention which is further set forth under the following claims:- WE CLAIM: 1. A process for preparation of coir composite board comprising preparation of resin followed by impregnating coir felt sheets with resin thus prepared, curing in atmosphere for 15-20 minutes, drying of resin impregnated sheet at 100C, and hydraulic pressing at 150 to 170°C wherein the resin is prepared by reacting pre-heated at 30-40^0 aqueous solution of phenol crystals with formalin in the ratio of 1:1.3 to 1:1.15 at elevated temperature of 50-70'^C using an alkaline catalyst such as sodium hydroxide. 2. A process for preparation of coir composite board as claimed in claim 1 wherein the said aqueous solution, ratio by weight of phenol crystals to water is preferably 9:1. 3. A process for preparation of coir composite board as claimed in claim 1 wherein the said pre-heating of phenol solution is preferably carried out at 35'C. 4. A process for preparation of coir composite board as claimed in claim 1 wherein the reaction of phenol with formalin is carried out at preferably 600C. 5. A process for preparation of coir composite board as claimed in claim 1 wherein the said hydraulic pressing is carried out at temperature of preferable at 160°C. 6. A process for preparation of coir composite board as claimed in claim 1 wherein the working pressure for said hydraulic pressing is around 30kg/cm2. 7. A process for preparation of coir composite board as claimed in claim 1 wherein dwell time for said hydraulic pressing is preferably around 30 minutes. 8. The coir composite board prepared by the process substantially as herein described and illustrated.

Documents:

193-che-2003 abstract.pdf

193-che-2003 claims.pdf

193-che-2003 correspondence others.pdf

193-che-2003 correspondence po.pdf

193-che-2003 description (complete).pdf

193-che-2003 drawings.pdf

193-che-2003 form-1.pdf

193-che-2003 form-18.pdf

193-che-2003 form-26.pdf

193-che-2003 form-3.pdf