A process for preparing an adhesive composition, comprising the steps of:
preparing a gelled carrier portion, by adding from 1.5 to 10% by weight of a starch, based on the weight of said adhesive composition, to 20 to 40% by weight of water, mixing to disperse the starch in the water, then adding from 0.25 to 2.5% by weight of NaOH or KOH and mixing to constant viscosity to produce the gelled carrier portion
adding to said gelled carrier portion from 10 to 30% by weight of a water-soluble alkali metal silicate characterized by a molar ratio SiO2 :M2 O in the range from 1.5 to 4.0, where M is Na or K, then mixing the whole until substantially homogeneous;
adding a further 3 to 20% by weight of water and mixing until homogeneous; and
adding a further 2 to 25% by weight of starch and mixing until viscosity is substantially constant to produce a final adhesive composition having a solids content between 31.2% and 45% by weight.
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