Adhesive based on a starch and acrylamide graft copolymer
AssigneeAlco Standard Corporation
InventorsMark L. Kaspar, James F. Lowey
Life of this patent
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Abstract
An aqueous adhesive composition containing a graft copolymerized product of low amylose starch and acrylamide with rheological and remoistening adhesive properties suitable for coating low basis weight kraft paper on transfer roll coating equipment to make remoistenable sealing tapes. The desired properties of the adhesive composition are obtained by a controlled graft copolymerization together with a simultaneous gelatinization of the starch at temperatures below 210.degree. F. and with the essential addition of cupric or ferric ions before initiating the reaction. The resulting coatable adhesive has a comparatively low viscosity as required for transfer roll coating while retaining the improved adhesion properties of the acrylamide.
Claims16
An aqueous adhesive composition with a high solids content and having rheological properties permitting application by transfer roll coating to a reinforced sealing tape to form a remoistenable adhesive coating thereon, said composition comprising
- (a) water as a liquid carrier;
- and
- (b) a graft copolymer of a low amylose starch and acrylamide as the essential adhesive, said copolymer being obtained by a reaction simultaneously gelatinizing said starch and graft polymerizing said acrylamide thereto in said water at a solids content of about 45 to 60% by weight and in the presence of catalytic amounts of a free radical initiator and at least one water-soluble metal salt selected from the group consisting of cupric and ferric salts, said reaction being carried out at an elevated temperature and for a period of time sufficient to yield a viscosity of said coatable adhesive composition of less than 1,000 cps, measured on a Brookfield viscometer, #2 spindle at 20 rpm and 190.degree. F.
An aqueous adhesive composition with a high solids content and having rheological properties permitting application by transfer roll coating to a reinforced sealing tape to form a remoistenable adhesive coating thereon, said composition comprising
- (a) water as a liquid carrier;
- and
- (b) a graft compolymer of a low amylose starch and acrylamide as the essential adhesive, said copolymer being obtained by a reaction simultaneously gelatinizing said starch and graft polymerizing said acrylamide thereto in said water at a solids content of about 40 to 45% by weight and in the presence of catalytic amounts of a free radical initiator and at least one water-soluble metal salt selected from the group consisting of cupric and ferric salts, said reaction being carried out at an elevated temperature and for a period of time sufficient to yield a viscosity of said coatable adhesive composition of less than 500 cps, measured on a Brookfield viscometer, #2 spindle at 20 rpm and 190.degree. F.
Dependencies are inferred from the claim text.