Title of Invention

AN IMPROVED PROCESS FOR MAKING PULP FROM FIBROUS BIOMASS USEFUL FOR MAKING PAPER

Abstract

An improved process for making pulp from fibrous biomass useful in making paper by drying fibrous biomass by known methods, cutting the dried fibrous biomass if required, digesting the dried and cut biomass in presence of sodium hydroxide solution at a pressure in the range of 60-140 psig, temperature in the range of 120-180 deg. C for a period in the range of 15-60 minutes to obtain semi-digested swelled biomass, washing the resultant biomass with water, passing the washed, semi digested, swelled biomass through a plurality of pressure rollers having ascending pressure to obtain the pulp.

Full Text

The present invention relates to an improved process for making pulp from fibrous biomass useful for making paper. Growing demand, limited supply and rising cost of materials/ products have motivated researchers to investigate the potential of using new resources for making alternative materials. Naturally occurring renewable materials i.e. fibrous biomass like Straw, Pine Needles, Esparto, Hemp, Broom Grass, Bagasse, Cornstalks, Pineapple Leaves, Forest Litter/biomass, Sagon Tree Leaves, Arecanut/ Palm Fibre which are wastes may become source of making useful value added products. Pine Needles is one of them. This has been found useful for converting it into pulp and then to hard board, wall paper. The paper made by using the said process is used for decorative purposes of the walls of buildings. This avoids the white/ colour washing or painting of the walls. Use of wall paper on walls of buildings saves time and gives instantaneous finish ready to use. Under this invention the development for making wall paper using Pine Needles is carried out along with the process technology development. This technology is aimed at utilizing fibrous biomass such as straw, Pine Needles, Esparto, Hemp, Broom Grass, Bagasse, Cornstalks, Pineapple Leaves, Forest Litter/ biomass, Sagon Tree Leaves, Arecanut/ Palm Fibre etc. which are the agro waste products. The products is cost effective in comparison to other commercial products available. These fibrous biomasses as stated above are abundantly available and have high potential to be used as a starting material for paper making. Pulping of fibrous material is the beginning phase of paper making. The first basic step in pulp preparation is pulping. Pulping is a process to reduce the raw material to the fibrous state. Pulping processes are of three principal types, mechanical; chemical and semichemical. The mechanical process involves the reduction of wood or other fibrous material to the fibrous state by mechanical means, generally by grinding raw material to a pulp against a large grindstone. The chemical process involves cooking of the raw material with chemicals which selectivly remove lignin and other impurities, isolate, and partially purify the individual fibres. There are three major chemical processes of commercial importance, namely, the soda, sulphate, and sulphite. The semichemical process involves an initial treatment for softening the raw material followed by mechanical reduction to the fibrous state (Pulp & Paper Chemistry & Chemical Technology, Vol.1, by James P. Casey, Interscience Publishers, New York, 1952). In semi-chemical pulping the two processes are combined together with optimisation. Different methods of pulping are used for different type of fibrous biomass. Some of them reported in literature are described here in brief. Straw is a seasonal crop which is available only during the summer and early fall. Normally, the moisture content of straw varies from 8 to 14 % but straws having moisture up to 50 % are sometimes obtained. Too high a moisture content is undesirable because it results in rapid and extensive deterioration of the straw in storage due to rotting. High moisture also constitutes a fire hazard by promoting spontaneous combustion of the straw. Straw has a lower cellulose content than wood, but is spite of its low cellulose content, straw has a total carbohydrate fraction (holocellulose) approximately equal to that of wood. This is due to the high hemicellulose and low lignin content compared to wood. Ash content is greater than wood. Cereal straws, like all canes and grasses, contain a number of different cells. Straw fibers, which are principally derived from the bast cells in the internodes, are fairly long (about 1.5 meterXO, slender fibers with sharply pointed ends. In addition to these fibers, straw also contains short, non-fiberous cells consisting of epidermal cells, platelets, serrated cells and spirals which are derived from the pith, nodes, chaff, and rachies (heads). A considerable portion of the small cells is lost during cooking and washing of straw pulp. This reduces the yield, but is desirable from the standpoint of improved pulp quality. Among other fibrous biomasses Pine—Needles are the best suited material since its availablity and uniformity in quality is more in comparison to other biomasses. Pine trees are coniferous and classified under temperate forests. Himalyan Pine is a broadly pyramidal tree that reaches a height of 50-100 ft. It grows rapidly and is moderately long lived. It is fairly resistant to cold and drought which ensures regular availability of the Pine Needles through out the year. These coniferous forests cover about 2,600,000 hectare in India which is about 3.3 percent of the total forest area (total forest covers including temperate and tropical forests is 78,396,000 Hectares). These figures are for the year 1975 and taken from Timber Trend & Prospects in India 1960-75 published by Ministry of Food & Agriculture, Department of Agriculture, Govt. of India, pp 9 and 9 A. Coniferous forests include Deodar, Chirpine, Lue Pine, Khasi Pine, Spruce and Fir. Himalayas for the most part, Jammu & Kashmir, Punjab, Uttar Pradesh, Himachal Pradesh have dense coniferous forests while to smaller extent Assam and West Bengal. Efforts have been made to make boards and roofing shingles from Pine Needles (Regional Research Laboratory, Jammu and Central Building Research Institute, Roorkee). Literature is silent about the use of Pine Needles to make wall paper. No one has tried these Pine Needles for this purpose so far. The same case is with the other fibrous biomasses. Most of the above stated fibrous biomasses have not yet been tried for making paper or other materials alike. Esparto is a reed-like grass which grows abundantly. The plant, which grows to an ultimate height of 3-4 ft., consists of two parts, a hard stem, and soft blades, which are from 0.5 to 3.0 ft. in length. In harvest, the blades are pulled from the stems by hand, the roots and stems being left to provide a new crop. Esparto pulp is similar in properties to soda pulp from hardwoods. The fibers are somewhat shorter than those in straw, averaging about 1.1 mm in length, but the ratio of fiber length to fiber width is higher than that of straw. There are three principal hemp fibers: the true hemp (Cannabis sativa) , Manila hemp (Musa textiles) , and sisal hemp (Agave). The true hemp contains fibers having an average length of about 20 to 22 mm and a width of about 22 microns. Manila hemp fibers are much shorter, having an average length of about 6 mm and an average width of about 18 microns. Sisal has longer fibers than manila hemp. Similar is the Broom grass. Bagasse is the fibrous residue left after the crushing and extraction of sugar cane. Bagasse has been used extensively for the production of coarse insulating board. It contains fibers averaging about 1.7 mm in length and about 20 microns in diameter. Bagasse has the advantage over other agricultural waste as a source of papermaking fiber in that there is no problem of collection, since it exists as a by-product of a sugar mill. The stalks from corn are similar to bagasse and can be used for making approximately the same type of paper. The main object of the present invention is to provide an improved process for making pulp from fibrous biomass useful for making paper, which obviates the draw backs as detailed above. Another object of the present invention is to utilize fibrous biomass in place of wood, a scare? natural resource, and in the process utilising unexploited renewable materials (waste) i.e. Straw, Pine Needles, Esparto, Hemp, Broom Grass, Bagasse, cornstalks etc. to convert into value added product and to solve the hazardous impact on environment. Still another object of the present invention is to reduce the requirements of water, energy and process cycle time in the said process. Yet another object of the present invention is to provide paper made using the pulp obtained from fibrous biomass. In the improved process of the present invention the various steps comprise of drying of the biomass in an oven at moderately high temperature, cutting the dried biomass if required into smaller size, weighed dried and cut biomass isdigested in a digestor such as autoclave under pressure and temperature alongwith the solution of sodium hydroxide of known strength, the digested biomass is washed with fresh water and passed through series of pressure rollers having ascending pressure to separate the fibers mechanically by increasing the pressure between the two rollers very slowly and the fibers thus obtained are then mixed with fresh water and spread over a wire mesh uniformly and water is allowed to drain by gravity filteration and the green paper thus made on the wire mesh is dried in an oven and this semi dried paper is then calandered and fully dried. The improved process of the present invention has the novelty of providing pulp from fibrous biomass having maximised fibre length which in turn imparts extra tensile strength to the paper produced there from. The inventive step(s) essentially consists of combining chemical pulping with mechanical fibre separation technique. This combination of two steps reduces the water requirement, saves energy consumption and over all process cycle time by around 50 % i.e. reduces the cycle time to 3-4 hrs. from 7-8 hrs. in chemical pulping alone. Accordingly the present invention provides an improved process for making pulp from fibrous biomass useful in making paper which comprises drying fibrous biomass by known methods, cutting the dried fibrous biomass if required, digesting the dried and cut biomass in presence of sodium hydroxide solution of the strength in the range of 2 to 10 % at a pressure in the range of 60-140 psig, temperature in the range of 120-180 deg. C for a period in the range of 15-60 minutes to obtain semi-digested swelled biomass, washing the resultant biomass with water, passing the washed, semi digested, swelled biomass through a plurality of pressure rollers having ascending pressure to obtain the pulp. In an enbodiment of the present invention the biomass used is straw, Pine Needles, Esparto, Hemp/ Broom Grass, Bagasse, Cornstalks. In another embodiment of the present invention the drying of the fibrous biomass may be carried out using known methods such as sun drying, oven drying at a temperature in the range of 40-60°C. In another embodiment of the present invention the fibrous biomass may be cut to a size in the range of 5-6 cms. In yet another embodiment of the present invention the sodium hydroxide solution used may be of strength in the range of 2-10% by weight. In another embodiment of the present invention, the sodium hydroxide solution may be reused by adding make up sodium hydroxide and water. In yet another embodiment of the present invention the pressure rollers used may be of pressure in the range of 2 to 10 psig. Accordingly the present invention provides paper made by known methodjxfrom p«lp obtained above. In yet another embodiment of the present invention, calcium oxi chloride may be used to bleach the pulp and to make the white paper. In the process of the present invention, the paper made acquired the average properties i.e. initial moisture content on dry basis 2.18 wt percent, tensile strength at break 0.105 Kg/mm2 and weight per unit area 177.0 gms/m2. In an embodiment of the present invention paper made using pulp prepared from Pine Needles is described below? Various steps of the said process comprise of drying of the Pine Needles in an oven at moderately high temperature, cutting the dried Pine needles into smaller size manually using scissors, weighed dried and cut Pine Needles are put on the grate of the vertical high pressure autoclave along with a solution of sodium hydroxide of known strength ensuring the whole of the Pine Needles are completely dipped into the solution then the cover of the autoclave closed and the heating is started maintaining the pressure inside the autoclave, then the digested Pine needles are washed with fresh water and passed through two roll mixture to separate the fibers mechanically by increasing the pressure between the two rollers very slowly and the fibers thus obtained are then mixed with fresh water and spread over a wire mesh uniformly and water is allowed to drain by gravity filteration and the green paper thus made on the wire mesh is dried in an oven and this semi dried paper is then calandered and fully dried. The process comprises of drying of the Pine Needles in an oven at temperature range from 40-60(C and then cutting the dried Pine needles into smaller size ranging from 5 cms. to 6 cms. manually using scissors. Dried and cut Pine Needles (30-100 grams) are put on the grate of the vertical high pressure autoclave and a solution of sodium hydroxide. Solution of sodium hydroxide is prepared by using 7-35 grams of sodium hydroxide in 300-1000 ml of water. Solution of sodium hydroxide is poured into the autoclave ensuring that the whole of the Pine Needles are completely dipped into the solution then the cover of the autoclave closed and the heating is started maintaining the pressure inside the autoclave at 60-140 psig and temperature at 120-180oC for 15-65 minutes. The digested Pine needles are washed with fresh water and passed through two roll mixture to separate the fibers mechanically by increasing the pressure between the two rollers very slowly. Fibers thus obtained are mixed with fresh water and spread over a 60 micron wire mesh of size 30 cms x 30 cms. uniformly and water is allowed to drain by gravity. Green paper thus made on the wire mesh is dried in an oven at a temperature of 65oC for 30-60 minutes. The semi dried paper is then calandered and fully dried. The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention. Example 1 The dried Straw 40 grams of it was put on the grate of the vertical high pressure autoclave. A solution of sodium hydroxide was made by dissolving 5 grams of it into 400 ml water. This solution was then poured into the autoclave. It was ensured that the whole of the Straw was completely dipped into the solution. •!'-'• The cover of the autoclave then closed and the heating was started. The pressure was maintained at 60 psig at a temperature of lOOoC for 30 minutes. Then after cooling the digested Straw was washed with water. The fibers thus obtained were then mixed with fresh water and spread over a 60 micron wire mesh uniformly and water was allowed to drain. The green paper thus made on the wire mesh was dried in an oven at a temperature of 65oC. The semi dried paper was then calendered and then fully dried. Example 2 60 grams of cut, washed and dried Bagasse was put on the grate of the vertical high pressure autoclave. A solution of sodium hydroxide was made by dissolving 21 grains of it into 100 ml water. This solution was then poured into the autoclave; Fresh water is then added so that the whole of the Bagasse was completely dipped. The cover of the autoclave then closed and the heating was started. The pressure was maintained at 80 psig at a temperature of 120°C for 45 minutes. Then after cooling the digested Bagasses was washed with fresh water and passed through two roll mixture to separate the fibers mechanically by increasing the pressure between the two rollers very slowly. The fibers thus obtained were then bleached by using 10 percent solution of calcium oxy chloride and the bleached fibres were then again washed with fresh water. The washed pulp is mixed with fresh water and spread over a 60 micron wire mesh uniformly and water was allowed to drain. The green paper thus made on the wire mesh was dried in an oven at a temperature of 65oC and semi dried paper was then calendered and then fully dried. Example 3 80 grams of cut Pine Needles were put on the grate of the vertical high pressure autoclave. 880 ml solution of 4 percent of sodium hydroxide was made and poured into the autoclave. The cover of the autoclave then closed and the heating was started. The pressure was maintained at 140 psig at a temperature of 180oC for 15 minutes. After cooling the digested Pine needles were washed with water and passed through two roll mixture to separate the fibers mechanically by increasing the pressure between the two rollers very slowly. The fibers thus obtained were then bleached by using 20 percent solution of calcium oxy chloride and the bleached fibers were then again washed with fresh water. The washed pulp is mixed with fresh water and spread over a 60 micron wire mesh uniformly and water was allowed to drain. The green paper thus made on the wire mesh was semi dried in an oven at a temperature of 55oC. The semi dried paper was then calendered and then fully dried. The main advantages of the present invention are; 1. The requirement of water, a scarce resource, is drastically reduced in the order of 50%. 2. Requirement of energy is drastically reduced in the order of 25%. 3. Required time for digestion is reduced to maximum 65 minutes in comparison to cycle time for digestion of wood. 4. Used sodium hydroxide solution can be reused/ recycled after adding make-up sodium hydroxide. 5. Saving of scarce forest resource by using biomass. 6. 30 % pulp as compared to 25 % by other conventional methods. 7. In the process of the present invention the paper made acquired the average properties i.e. initial moisture at break 0.105 Kg/mm2 and weight per unit area 177.0 content on dry basis 2.18 wt percent, tensile strength at brea gms/m . We claim: 1. An improved process for making pulp from fibrous biomass useful in making paper which comprises drying fibrous biomass by known methods, cutting the dried fibrous biomass if required, digesting the dried and cut biomass in presence of sodium hydroxide solution of the strength in the range of 2 to 10 % at a pressure in the range of 60-140 psig, temperature in the range of 120-180 deg. C for a period in the range of 15-60 minutes to obtain semi-digested swelled biomass, washing the resultant biomass with water, passing the washed, semi digested, swelled biomass through a plurality of pressure rollers having ascending pressure to obtain the pulp. 2. An improved process as claimed in claim 1 wherein the biomass used is straw, Pine Needles, Esparto, Hemp, Broom Grass, Bagasse, Cornstalks. 3. An improved process as claimed in claims 1 and 2 wherein drying of the biomass is carried out using known methods selected from sun drying, oven drying at a temperature in the range of 40-60°C. 4. An improved process as claimed in claims 1 to 3 wherein the biomass is cut to a size in the range of 5-6 cms. 5. An improved process as claimed in claims 1 to 5 wherein the pressure rollers used is of pressure in the range of 2 to 10 psig. 7. An improved process for making pulp from fibrous biomass useful for making paper, substantially as herein described with reference to the examples.

Documents:

1507-del-1999-abstract.pdf

1507-del-1999-claims.pdf

1507-del-1999-correspondence-others.pdf

1507-del-1999-correspondence-po.pdf

1507-del-1999-description (complete).pdf

1507-del-1999-form-1.pdf

1507-del-1999-form-19.pdf

1507-del-1999-form-2.pdf