Evaluation of DRY Strength Additives FROM NATURAL Resources of Indian ORIGIN

EVALUATION OF  DRY STRENGTH ADDITIVES  FROM NATURAL RESOURCES OF  INDIAN ORIGIN   A.K. Ray ,and Ghosh U K

Department of Paper Technology, Indian Institute of Technology Roorkee, Saharanpur Campus, Saharanpur

ABSTRACT

There are many additives used during paper making, such as, in the beating or refining process  and as strength additives. It is well known that additions of dry strength resin increase the mechanical strength properties of paper such as tensile and burst indices  by increasing the interfiber bonding without affecting the tear strength.It is used to reduce the fuzz or lint on the paper surface, and to increase the internal ply-bond strength. The most common dry strength additives are starch and its substitutes like oxidized starch, cationic starch and poly-acryl-amide polymer. These are normally synthetic and some are semi synthetic in nature. Though additions of  polyacrylamides can give superior properties but it is very expensive compared to starch based chemicals. In India gums like  guar gum, locust bin gum  and seed gum of sebania aculeate etc. are available in plenty which can be a good substitute of either cationic starch or polyacrylamides. Earlier trials  has been tried, but the data are not available in literature. An attempt has been made in the present investigation to explore the potential   of guar gum  as dry strength additives in paper industries. Experiments were conducted with Guar Gum at various percentage (0.5 to 5.0%) on OD fibers.

The freeness value( actually slowness), ⁰SR of the pulp were also varied  between 35 to 45⁰SR, and the results were evaluated. To compare its effects parallel runs were also tried with oxidized starch, maintaining the same doses of additive, ⁰SR value , mixing time and degree of agitation. For  a given strength  guar gum additive requires  less magnitude of  refining. It is expected that by decreasing refining ,tearing strength, drainage aid requirements and permeability will decrease and consequently demand of refining energy will  also decrease.

 From the experimental data it is found that guar gum can be a promising dry strength additives which can give requisite dry strength in paper. A blank test without addition of dry strength additives has also been tried for comparison purposes. However all these cases that is blended with guar gum and with oxidized starch the internal sizing agent has been kept constant i.e. rosin and alum with a fixed ratio(1:4).