Title of Invention

"A PROCESS FOR PRODUCING HOMOGENEOUS PIGMENTED COMPOSITE PARTICLE BOARDS FROM RICE HUSK"

Abstract

An improved process for producing composite particle boards from rice husks comprising the step of subjecting rice husk to the step of splitting, blending the cleaned and splitted rice husk with 5 to 20% moisture free resins wherein resin is prepared by admixing cashewnut sheel liquid (CNSL) and cardenol with phenol, heating said mixture to a temperature 50 to 95° C in the presence of alkaline catalyst and then adding paraformaldehyde to said reaction mixture and conventional stains/pigments comprising 20 to 90% by wt. of cashewnut shell liquid or cardenol with 10 to 20% by wt. of conventional phenol paraformaldehyde alkaline catalyst so as to obtain a furnish, spreading the furnish to form a layer and then subjecting the same to the step of hot pressing at a temperature of 150 to 190° C and then cooling the same to form the board.

Full Text

MANUFACTURE OF PARTICLE WAARD OF RICE HUSKS Field of Invention This invention relates to a process for producing homogenous pigmented composite particle boards from rice husk and composite boards produced therefrom. Prior Art It is known in the art to produce particle board from agro-wastes using phenolic resins- Such a known process envisages the step of blending rice husk with a phenolic resin containing a substantial quantity of water. Due to the presence of water, the blend is subjected to the step of drying for removal of the excess moisture content during or after the resin is coated on the rice husk or furnish. The furnish is then hot pressed to form particle boards. Several disadvantages are associated with the use of such a known phenolic resin. One such disadvantage is that a drying operation results in a procuring of the resin, thereby diminishing its adhesive strength and resulting in poor quality particle boards. Moreover, since rice husk is a material of low bulk density, handling of the resin coated husk or furnish for drying is not convenient. Another disadvantage is that of the control of moisture content of the furnish. It is generally known that the furnish should have a moisture content, but which simultaneously should not be substantial in quantity aS an excess of moisture could result in the formation of blisters or steam packets in the formed boards. Thus, as a rice husk itself contains moisture the use of the known resin containing substantial quantities of water results in a furnish having a high moisture content which is detrimental to the formation of the board. Further more, even if the furnish is subjected to the step of drying, it is difficult to control the correct content of moisture in the furnish. Objects of the Invention An object of this invention is to propose an improved process for the production of composite particles boards from rice husk and composite boards produced therefrom. Another object of this invention is to propose a process for the production of composite particle boards from rice husk which no longer reauires the step of drying of the furnish. Still another object of this invention is to propose a process for the production of composite particle boards from rice husk which no longer is attended with the disadvantage of formation of steam pockets or blisters. Yet another object of this invention is to make coloured or pigmented boards by adding the required stain or pigments as well as wax to the husk and then add resin and mix it for a period of time. This ensures that when the furnish comes out, it has a homogeneous colour. This process has never been achieved anywhere else in the world and is a process devised by the inventors for the first. time in Malaysia. The homogeneous pigmented boards have many advantages:- a) It gives a good look and improves aesthetics. b) It provides greater variety by usage of different colours in different environments. c) It provides a long lasting board because of silica's presence. d) It is homogeneous which is desirable is flooring or wall paneling construction. e) The wax introduced into the mix improves durability and provides and added sheen. f) The boards do not require lamination, veneering, overlay or painting to enhance its aesthetics or physical properties unlike the plain rice husk composite particle board. Description of the Invention According to this invention there is provided an improved process for producing composite particle boards from rice husks comprising the step of subjecting rice husk to the step of splitting, blending the cleaned and splitted rice husk with 5 to 20% moisture free resins wherein resin is prepared by admixing cashewnut sheel liquid (CNSL) and cardenol with phenol, heating said mixture to a temperature 50 to 95° C in the presence of alkaline catalyst and then adding paraformaldehyde to said reaction mixture and conventional stains/pigments comprising 20 to 90% by wt. of cashewnut shell liquid or cardenol with 10 to 20% by wt. of conventional phenol paraformaldehyde alkaline catalyst so as to obtain a furnish, spreading the furnish to form a layer and then subjecting the same to the step of hot pressing at a temperature of 150 to 190° C and then cooling the same to form the board. It is generally known that rice husk is of a boat shape. It has now been found that such a rice husk is not receptive to a uniform coating of resin. Thus, in accordance with this invention, rice husk is first subjected to the step of splitting to provide a surface more receptive to resin. Such a step of splitting is important, as in the absence thereof, the bulk density of rice husk would be low and, consequently, the thickness of furnished mat would be high, and that when such a furnished mat is subjected to the step of pressing, the edges of the mat would tend to spread. As the density in the spread portion would be lower than the main body portion of the board, the spread portion would need to be trimmed and, thereby, result in a loss of material The split rice husK is subjected to the step of cleaning and grading by any known method for removal of dust and other extraneous matter. One of the concepts of the present invention resides in the use of substantially moisture free resin so that, firstly, the moisture content of the furnish can be controlled and, secondly, the step of drying of the furnish is avoided. The step of control on the moisture of the furnish is important, as the presence of a correct moisture content provides a board without blisters and steam pockets. The furnish should contain a moisture content of 10-15% based on dry weight, and preferably 10-12%. Normally rice husk itself has 9-12% moisture content. However, in certain instances, there is no need to add water as the moisture content is higher due to high relative humidity. As the additive of stains increases the moisture content by 2-5%, so the moisture content of the husk must be controlled in order to avoid blisters and steam pockets. If the moisture content is higher, then a higher temperature and time will be required, resulting in loss of production and high energy cost.. A moisture content of 10 to 127. in the furnish is required because when the furnish is subjected to the step of hot pressing, the resin melts but does not flow adequately to wet adjacent particles. Further, to permit a blending of rice husk to form the board, the surface of rice husk must get together, and for which a flexibility of rice husk is required, Such a flexibility is imparted through the moisture contained in the furnish. If the moisture content increases between 12-157. a better resin coating on the rice husk is achieved. This will help in good stacking and reduces the chances of warping. Higher moisture content will give unequal distribution of colour and will result irt patches. Lower moisture content will give less flexibility and the boards will warp. If the moisture content contained in the furnish is greater than 15%, and as temperature as high as 150 to 190°C are employed in the step of hot pressing, only a negligible amount of moisture is allowed to escape from the edges. Thus, water is entrapped at high temperature during such a step of pressing, which is converted to steam on release or removal of pressure, and which results in the possible Formation of blisters, However, if the furnish contains less than 1187. of moisture, the flexibility property is not present and, thereby, the wetting of the rice husk with resin is reduced. In accordance with this invention, rice husk is blended with 5 to 20% of resin to obtain a furnish. If more than 20% of resin is added to rice husk, the process is uneconomical. if the furnish contains leas that 5V. of resin, the board does not contain enough strength. Preferably, 10 to 12% of resin is added to rice husk. In making pigmented boards, resin and stains • are added in the blenders with husk in the desired ratios to obtain the right colour. Any mistake in the colour- and resin ratio cannot be overcome in the later stage of the process. Less colour will result in patches on the boards and more colour will give too much concentration which will result in boards losing aesthetic value. The furnish layer is subjected to the step of hot processing at a temperature range of 1500C-190°C, but preferably 155°C-185oC. The pressure applied to the furnish layer is 110 Kg/in2, depending upon the densities of the boards, For pigmented boards the pressure requirement is 155 Kg/in2 —l75Kg/.in2 . The density of the pigmented boards will very from 850-870 Kg/m2 , The pigmented boards prepared by this process can be used fors — a. Flooring b. Wall Paneling c. Partitioning d. Furniture manufacture The pigments are in combination and mixtures. In combination, two different pigments are produced and then mixed together. Far the mixing, a mixer may be employed to mix the two pigments homogeneously. In this way, the chances of improper mixing is minimized, For mixture, two different pigments are added together in a kettle with an agitator to mix the pigments homogeneously. These pigments are then added to the resin and the husk to get the desired result. This invention further relates to a process for preparing an improved adhesive resin suitable for bonding rice husk which comprises in the steps of admixing cashewnut shell liquid and/or cardenol with phenol, heating the said mixture in presence of an alkaline catalyst, adding paraformaldethyde to the said reaction mixture where the heating is continued to complete the condensation reaction and thereafter cooling the reaction product. In the preparation of the improved resin according to the invention, the reactants are taken according to the proportion set forth belows- CNSL/Cardenol : 20% to 90% by weight Phenol : 10% to 80%. by weight Paraforntaldehyde equivalent to 1.4 to 2 moles of formaldehyde based on the CNSL and phenol used. Alkaline catalyst in the range of 1 to 5% by weight of the CNSL/Cardenoi and phenol used. The catalyst is dissolved in 2 to 10 times its weight of water before adding to the condensation mixture. The condensation takes place at the temperatures range of 50 to 05°C. The heating is generally continued for a. period of 25 to 45 minutes initially. The second stage of condensation after the addition of a further quantity of phenol is carried out at the temperature range of 55 to 95°C for a period of 30 to 45 minutes to complete the condensation reaction. WE CLAIM; 1. An improved process for producing composite particle boards from rice husks comprising the step of subjecting rice husk to the step of splitting, blending the cleaned and splitted rice husk with 5 to 20% moisture free resins wherein resin is prepared by admixing cashewnut sheel liquid (CNSL) and cardenol with phenol, heating said mixture to a temperature 50 to 95° C in the presence of alkaline catalyst and then adding paraformaldehyde to said reaction mixture and conventional stains/pigments comprising 20 to 90% by wt. of cashewnut shell liquid or cardenol with 10 to 20% by wt. of conventional phenol paraformaldehyde alkaline catalyst so as to obtain a furnish, spreading the furnish to form a layer and then subjecting the same to the step of hot pressing at a temperature of 150 to 190° C and then cooling the same to form the board. 2. An improved process as claimed in claim 1 wherein the moisture content of the furnish is kept between 10 to 15% so as to facilitate the step of hot pressing. 3. An improved process as claimed in claim 1 wherein 1.4 to 2 moles of paraformaldehyde is present in the resin. 4. An improved process as claimed in claim 1 wherein 1 to 5% by weight of alkaline catalyst is present in the resin. 5. An improved process as claimed in claim 1, wherein reaction mixture used to prepare resin is heated for a period of 25 to 45 minutes initially and then further heated at a temperature of 55 to 95° C for a period of 30 to 45 minutes. 6. An improved process as claimed in 1, wherein said step of hot pressing of the furnace layer is completed preferably at a temperature of 155 to 195° C and at a pressure of 110 kg/In2 . 7. An improved process for producing composite particle boards from rice husks substantially as herein described and illustrated.

Documents:

311-del-1998-claims.pdf

311-del-1998-correspondence-others.pdf

311-del-1998-correspondence-po.pdf

311-del-1998-description (complete).pdf

311-del-1998-form-1.pdf

311-del-1998-form-19.pdf

311-del-1998-form-2.pdf

311-del-1998-form-26.pdf

311-del-1998-form-3.pdf

311-del-1998-form-5.pdf

311-del-1998-form-6.pdf

311-del-1998-gpa.pdf

311-del-1998-petition-138.pdf