Leucaena seed extract could cut paper-making costs
A new guar gum substitute derived from ipil-ipil (Leucaena
leucocephala) seeds could cut paper-manufacturing costs by as much as 30 per
cent in some developing countries, according to researchers in the Philippines.
The guar substitute, formulated by researchers at the Forest
Products Research and Development Institute in Los Banos, has aroused the
interest of paper manufacturers, who normally import the gums used in
production. Use of Leucaena leucocephala, a well-known agroforestly tree species
grown widely in the tropics, would provide a locally-grown, economical
replacement for the expensive chemical imports. According to an institute
spokesman, Philippine imports of gumbased additives for the paper industry, food
products and cosmetics averaged 5 500 tons per year between 1985 and 1987,
representing US$2.8 million.
Gum additives are mixed with paper pulp at various stages of the
paper-making process, and are used as sizing agents, fillers, strengthening
agents, pigments, defoamers, slimicides, surfactants, dispersants and pitch
Three varieties analysed
Workers at the institute have analysed the chemical composition
of three varieties of ipil-ipil seed, including the K-28 variety of the El
Salvador group and the K-6 and K-8 varieties from Peru and Mexico, respectively.
The K-28 is one of the so-called "Hawaii giants", said to have been introduced
in the Philippines some 12 years ago to provide shade for coffee plants.
The finely-ground seeds of the three varieties produced two
forms of gum additive - extract and powder - for paper. Experiments showed that
additive levels of 0.2 to 0.4 per cent of powder imparted considerable strength
to unbleached kraft pulp, kraft cuttings and sugar cane bagasse hand-sheets
(cellulose-rich sugar cane residues after crushing).
Based on the absolute dry weight of the pulp, the addition of
0.5 per cent aqueous crude gum extract obtained from giant K-28 seeds greatly
increased the dry-tensile strength of the pure bagasse and lauan pulp
hand-sheets. Ipil-ipil gum costs roughly US$1.00 per unit, compared to
approximately US$1.50 for imported guar gum. It also saves on fibres and fillers
and results in clearer waste water.
Researchers believe a paper mill that produces 100 tons per day
of dry strengthened paper using 400 kilograms of ipil-ipil gum could save
approximately 600 000 pesos (US$30 000) when operating on a 300-day working
L. Ieucocephala is known to agroforesters as an MPT
(multi-purpose tree) species (Ceres No. 133). Its wood is used for construction,
fuelwood and charcoal, its leaves as an animal fodder and its cooked fruit as a
food for humans. Being a leguminous, or nitrogen-fixing species, the ipil-ipil
also has a beneficial effect on soils.