Cellulose and Paper Division

Brief Description

The Cellulose and Paper Division , Forest Research Institute (FRI) has been the frontal institution in the field of pulp and paper. Science and technology in India. The rapid expansion of pulp and paper industry in the country using different lignocellulosic material (bamboo, tropical hardwood, agricultural residue and grasses) for variety of cultural , industrial and speciality paper and newsprint was possible only due to extensive and pioneering research work carried out at forest research institute.

Thrust Area

Increasing productivity from same unit of raw material.
Exploration and identification of new chemical additives as pulping aids and waste utilisation.
Evaluation and screening of Poplar clones for pulp and papermaking, keeping environmental considerations and shortage of raw materials in view.
Environmental pulping and bleaching processes.
Pollution control in pulp and paper industry through work utilization.

Highlights of Achievements

Activation and modification of high yield pulps from hardwoods species for enhanced productivity.

High yield pulps are rich in lignin which is hydrophobic in nature. As the amount of lignin increases there is deterioration in strength properties (bonding strength) and the pulp requires more energy in mechanical/chemical treatments. These draw backs limit the application of high yield pulps in papermaking furnishes. It is necessary to improve their mechanical properties and bleachability at energy application as low as possible. The prime aim is therefore to develop a process to make high yield pulp lignin hydrophilic without impairment in yield to improve fibre swelling, bonded area, specific surface area etc. and consequently improve the mechanical strength properties and reduce energy requirement. Degree of hydrophillation of lignin in high yield pulps is responsible for the level of improvement of strength properties and bleachability.

The cost and benefits of the post treatment of high yield pulps for improving their properties, bleachibility and beatibility was assessed in terms chemical inputs and reduction in energy consumption during beating. Reduction of energy during beating of modified pulp was 350kwh/t from 500 kwh/t. The total cost of inputs (energy and Chemicals) reduced from Rs3000/t to 2500/ with the added advantage of improvement in strength properties in terms of Tensile index by 30-140%, Burst index by 18-140% and Tear index by 14-50%

It is revealed form the above that the modification sequences adopted are economically viable and results in highly improved high yield pulps with respect to strength properties and energy requirement.Improvement of strength properties make the high yield pulps suitable for a variety of paper and thus enhance their usage in papermaking furnishes which would result in reduction of inputs.This would then atomically enhance the productivity for same unit of raw material.

Utilisation of spent pulping liquor lignin with respect to their polymeric application - production value aided products for Industrial application

Researches have been carried out extensively to utilise spent liquor lignin from wood and non wood for production of Nuclear sulphonated product. The nuclear sulphonated product was evaluated for :

As solvent for isolated lignin - 1% solution of these modified lignin sample i.e. lignosulphonates in 50% ethanol were prepared and lignin solubility was observed .It was observed that these lignin products possesses very high dissolving power for isolated industrial lignin ( a 10g/l solution of sulphonated lignin in 50% ethanol could produce a solution of over 300g/l concentration of industrial soda lignin).
As dispersing agents/emulsifiers- The sulphonated lignin derivatives were tested for their application as dispersing agent/emulsifier.The value of Standard Dispersion Number was in the range of 0.02 to 0.04 indicating that the lignosulphonates produced can be used as emulsifying /gelating agents
As an additive in enhanced Secondary oil recovery- The product tested in KDMIPE, ONGC Dehra Dun revealed that the addition of 2% of lignosulphonates can partially replace the costly petroleum sulphonates presently being used for enhanced oil recovery in terms of reduction in Interfacial tension (Dynes/cm).
As an additive for use in oil well drilling- Tests conducted at IDT, ONGC, D.Dun indicates that 1% addition level of lignosulphonate are stable upto 160oC and apparent viscosity of Bombay high crude oil emulsion using Bentonite clay reduced from 42.cps to 18.00 at room temperature in fresh water.

Polyols and Polyurethane adhesive and coatings : Modification of lignin to produce polyol and polyurethane for application as adhesive and coatings is another important area on which researches are directed in our laboratories.The polyol and polyurethane were tested for strength of wood/paper properties and chemical resistance. The results were encouraging.

Oxygen Bleaching

In order to reduce the environmental pollution, researches were carried out to replace the conventional bleaching sequence involving chlorinations, alkali extraction/ hypochlorination etc. by much environmental friendly bleaching sequences using molecular oxygen followed by partial or complete elimination of elemental chlorine by the use of chlorine dioxide/hydrogen peroxide/ hypochlorite. Kraft pulps of 20 and 40 kappa number (degree of delignification) of Eucalyptus tereticornis and Anthocephalus indicus were prepared after a series of experiments.

All the pulps were subjected to physico-chemical analysis viz, solubilities, kappa number, holocellulose, pentosans etc. and strength properties determination. Evaluation of pulps obtained under optimum conditions and their bleaching is in progress. Bagasse soda pulp (kappa number 40) and mechano-chemical pulp (kappa number 101 and 83.4) were prepared and treated with oxygen 8.00 kg/cm2 pressure, 90oC for one hour using 2.00% alkali. Kappa number of pulps was reduced by 5 to 7 points. These oxygen pretreated pulps were bleached with hypochlorite in two stages alongwith control sample. Gain in brightness by 68 point was observed in case of oxygen pretreated pulps at the cost of marginal drop in bleached pulp yield.

Recycling of Waste Paper

Laboratory scale deinking experiments on mixed waste were carried out using various combinations of NaOH, Na2CO3, sodium silicate, sodium salt of benzen sulphonic acid and detergent. Deinked pulp possessing optimum properties was bleached with calcium hypochlorite and hydrogen peroxide alone and also in combinations. It was concluded that hypochlorite bleaching was more suitable for computer waste (brightness, ISO 71.5%) and office waste (brightness ISO 72.09%) while hydorgen peroxide bleaching yielded better pulp from magazine grade paper (brightness 61.94% ISO) and newsprint (brightness 52.20% ISO).

Production of Corrugating Media from Populus Deltoides

Neutral sulphite semi-chemical (NSSC) pulp was prepared using different concentration of sodium sulphite and sodium carbonate. It was concluded that P. deltoides could be used for production of corrugating medium using NSSC pulping process.

Rayon Grade Pulp from Populus Deltoides

Rayon grade pulp was prepared from P. deltoides adopting prehydrolysis kraft pulping process followed by multistage (chlorination/alkali extraction/hypochlorite/ chlorine dioxide) bleaching sequence.

Biotechnological Modification of Dendrocalamus Strictus Fibres

Physico-chemical analysis of control and artifically decayed chips by a white rot fungi, Coriolus versicular revealed that in the initial period of decay, the crystallinity and degree of polymerisation of cellulose remain almost unaffected but accessible amorphous cellulose is more prone to degradation/metabolisation. Decayed sample yielded more pulp as compared to control sample which compensated for the material lost during inoculation. Brightness and bonding properties of unbleached chemical pulp were superior to that of control. Bleaching response of fungal pretreated sample was better than the control.

Complete elimination of sulphur and chlorine compounds in pulping and bleaching by MILOX process

Eucalyptus tereticornis chips were pulped in three successive stages using peroxy formic acid followed by formic and again with peroxy formic acid using four different doses of chemicals. Out of four pulps, one pulps was bleached by two stage hydrogen peroxide and one pulp was bleached using three stage of hydrogen peroxide. Pulps were evaluated for strength properties and brightness. The pulps exhibited adequate level of strength properties and brightness for variety of end uses.

Environmental protection through modified pulping and bleaching process-Alkaline peroxide pulping and bleaching of non-woods.

Oxygen delignification of wheat straw pulp of kappa number 28 was carried out to optimise the reduction in kappa number to about 50% without any loss in physical strength properties i.e. tensile index, burst index and tear index. Improvement in brightness was also determined. Analysis of effluent of each stage of bleaching was also done. Bleaching studies of soda and oxygen delignified soda pulp were done using chlorine dioxide, hypochlorite combination alongwith chlorine. Economics of different bleaching sequences were calculated.

Studies on modification of industrial lignin with respect to imparting delignification properties.

A new chemical additive has been identified. The results on bamboo and eucalyptus are encouraging with respect to increase in pulp yield , reduction in kappa number and improvement in strength properties. In case of Kraft pulping of Eucalyptus tereticornis, the addition of chemical additive registered 0.27-4.8% increase in pulp yield. 27.9% reduction of kappa number was achieved. The pulp produced with chemical additive registers improvement in strength properties i.e. tensile (5.9%), burst (10.2%) and tear indices (19.8%) as compared to blank pulp. Bleaching studied showed that at fixed chlorine charge the brightness increased by 16.8%. The resulting pulps required less bleaching chemicals to achieve same level of brightness .The bleached pulp had higher strength properties.

Effluent treatment in pulp and paper industry: production of nitrogen fertilizer/soil conditioner.

Soda lignin was isolated from wheat straw and treated with ammonia. Modified lignins were analysed. Lignosulphonate was isolated from spent sulphite liquor of wheat straw and treated with ammonia to incorporate nitrogen. Modified lignins under optimum conditions contained 10.8% and 11.58% nitrogen corresponding to 4.53 and 2.66 C/N ratio, respectively. Trials for application as fertilizer/soil conditioners were conducted and it was observed that N-modified lignin has marked advantage over unmodified lignin, control and urea. Silver oak and wheat grains were taken for trials.

Improved utilization of raw materials for pulp and papermaking including juvenile wood.

Three clones of P. deltoides (5years age), G-3,112910 and S7C3 were tested for their proximate chemical analysis. Conditions were optimised for preparation of cold soda pulps from poplar clones (10years age) for manufacture of newsprint grade paper. Cold soda pulps of nine clones were prepared at optimised condition using 30 gpl NaOH. The volume of spent liquor,pH and residual alkali were checked in each case.
Kraft pulps from 18 clones of P.deltoides (10 years age) were prepared using 16% active alkali. The screened pulp yield and kappa numbers of each pulp were determined. Environment friendly bleaching studies were started by giving oxygen pretreatment before hypochlorite and hydrogen peroxide stage. Conditions for oxygen pretreatment of kraft pulp for poplar clones were optimised 45-50% reduction in kappa number with 72-99% brightness gain was achieved by oxygen pretreatment.

Future Plans

To develop environmental friendly pulping and bleaching process.
Pollution abatement.

Research Facilities available equipment specialization etc.

All laboratory facilities for carrying out raw material analysis, pulping, bleaching and paper testing are available in the Division.

Services available e.g. wood identification, insect identification.

Consultancy in Pulp and Paper.
Analysis of Pulp and paper.

Sponsored Research

Alkaline peroxide mechanical pulping and bleaching (APMP )

APMP uses advanced chip pretreatment techniques to pulp and bleach wood prior to refining. The combination of pulping and bleaching in a single unit operation reduces the capital cost for an installation by decreasing the amount of equipment to produce bleached pulp. There are also significant operating cost advantages through reduced electrical power consumption, which is achieved by refining the pulp under alkaline conditions. Work carried out on Populus deltoides indicate that 75-78% brightness with sufficient strength properties at 85 % yield can be achieved by application of 3% hydrogen peroxide and 3-4 % NaOH with reduced energy consumption.

The experiments were conducted using prex system at initial stage with respect to dewatering efficiency and subsequent chemical treatments for preparation high brightness high yield pulps using APMP process.For large scale trail a compression cum dewatering unit was designed, got fabricated, procured and installed to increase the dewatering efficiency (1:4).Using this equipment APMP process was applied for pulping Poplar and Bagasse.Work on Poplar has bee successfully completed with respect dewatering efficiency and brightness improvement.78% brightness at 80% yield with adequate strength properties. The project is sponsored by Indian Paper Maker Association, New Delhi.

Production of high molecular weight and high purity alpha cellulose.

Alpha cellulose from Cotton linter and Bamboo were prepared at 1 Kg batch in laboratory .The alpha cellulose produced had 99% purity with 80% brightness and DP in the range of 800-2200.The technology was demonstrated to the sponserer Gujarat Alkali Chemical Limited (GACL) ,Gujarat. Work on eucalyptus is in progress.