GB772479A - A process for the manufacture of dry, cold-water-soluble binding agents, adhesives, finishing agents and the like from starch, a urea and an aldehyde - Google Patents

Abstract

A dry cold-water-soluble product is made by heating a mixture of disintegrated starch which may be esterified or etherified, water and either urea or an analogue thereof and an aldehyde or a precondensate thereof, while at the same time the mixture is pressed or spread out to a thin layer which is dried simultaneously or immediately thereafter. The disintegrated starches used are those of which a 15 per cent solution has a viscosity of at most 100 c.p. at 90 DEG C., e.g. dextrins, British gums and highly modified thin boiling starches. The urea-formaldehyde condensate may be etherified and/or esterified. Specified analogues of urea are thiourea, guanidine and glucoseureide. Part of the disintegrated starch may be pretreated with a urea and/or an aldehyde. The products may be used as thickening agents for rendering fabrics crease-resistant, abrasion-resistant or slip-free and to fix the pile thereof; for fixing pigments on textiles; as adhesives; for sizing paper; as a thickening and fixing agent in paper and textile printing; as a binding agent for powdered, granular or fibrous material (e.g. primings, cements, water colours, briquettes, foundry cores and fibre boards); or as a moulding material mixed with wood flour, bentonite, ground slate, asbestos, cellulose fibres, or fabric cuttings. Hardening of the product is effected with an acid or acid-producing substance. Water-soluble polysaccharides, e.g. cellulose ethers, may be added prior to, during or after the heating process. The products may be combined with other starch products, e.g. natural starches, thin boiling starches, dextrins, coldswelling starches, or cold-swelling starch ethers or esters. In examples: (1) a mixture of dextrin, dimethylol urea (or a mixture of 1 mol. of urea and 2 mols. of formaldehyde) of pH 5-11 is heated on a rotating cylinder to 130 DEG C. (2) A mixture of thin boiling starch and dimethylol urea or its dimethyl ether of pH 8 is heated on a rotating cylinder to 130-140 DEG C. (3) A mixture of an etherified disintegrated starch and dimethylol urea or its dimethyl ether of pH8 is heated on a rotating cylinder at 140 DEG C. (4) A urea-formaldehyde condensate is made by heating urea with formalin at pH 4 1/2 -5 and neutralizing with caustic soda; the condensate is then heated with dextrin as in Example (1). Specifications 494,927, [Group IV], 601,374, [Group IV (b)], 632,789 and 632,791, [Group IV (c)], are referred to.ALSO:A dry cold-water-soluble product is made by heating a mixture p of disintegrated starch which may be esterified or etherified water and either a urea and an aldehyde or a urea-aldehyde condensate to gelatinize the starch, while at the same time the mixture is pressed or spread out to a thin layer which is dried simultaneously or immediately thereafter. The disintegrated starches used are those of which a 15 per cent solution has a viscosity of at most 100 c.p. at 90 DEG C., elgl dextrins, British gums and highly modified thin-boiling starches. The urea-aldehyde condensate may be etherified and/or esterified. Specified ureas are urea, thiourea, guanidine and glucoseureide. Part of the disintegrated starch may be pretreated with a urea and/or an aldehyde. The products may be used as thickening agents for rendering fabrics crease-resistant, abrasion-resistant or slip free and to fix the pile thereof; for fixing pigments on textiles; as adhesives; for sizing paper; as a thickening and fixing agent in paper and textile printing; as a binding agent for powdered, granular or fibrous material (e.g. primings, cements, water colours, briquettes, foundry cores and fibre boards); or as a moulding material mixed with wood flour, bentonite, ground slate, asbestos, cellulose fibres or fabric cuttings. Hardening of the product is effected with an acid or acid-producing substance. Water-soluble polysaccharides e.g. cellulose ethers may be added prior to, during or after the heating process. The products may be combined with other starch products e.g. natural starches, thin-boiling starches, cold-swelling starches, or cold-swelling starch ethers or esters. In examples (1) a mixture of dextrin, dimethylol urea (or a mixture of 1 mil of urea and 2 mols of formaldehyde) of pH 5-11 is heated in a rotating cylinder to 130 DEG C. (2) A mixture of thin-boiling starch and dimethylol urea or its dimethyl ether of pH 8 is heated on a rotating cylinder to 130 DEG -140 DEG C. (3) A mixture of an etherified disintegrated starch and dimethylol urea or its dimethyl ether of pH 8 is heated on a rotating cylinder at 140 DEG C. (4) A urea formaldehyde condensate is made by heating urea with formalin at pH 4 1/2 -5 and neutralising with caustic soda; the condensate is then heated with dextrin as in Ex. (1). Specifications 494,927, 601,374, 632,789 and 632,791 are referred to.