GB1128374A - Carrier materials provided with a water-resistant deposit of a starch derivative - Google Patents

Abstract

1,128,374. Water-resistant coatings. W. A. SCHOLTEN'S CHEMISCHE FABRIEKEN N.V. 18 Nov., 1966 [19 Nov., 1965], No. 49140/65. Addition to 977682. Heading B2E. [Also in Division C3] A carrier material e.g. paper or paperboard, is provided with a water-resistant deposit of a starch derivative consisting of a reaction product of a water soluble or water dispersible melamine-aldehyde precondensate with a starch derivative, obtained by hydrolyzing starch at a temperature between 60‹C and 300‹C with an inorganic acid in the presence of urea and less than 50% water calculated on the weight of the mixture to such an extent that a 25% by weight aqueous solution of the starch derivative has an apparent viscosity of at least 10 cerstipoises e.g. 10 to 1500 ops, at 25‹C. An aqueous composition containing the starch derivative is applied to the carrier material and the material so treated is contacted with a water-soluble or water dispersible melamine-aldehyde precondensate so as to tender the starch derivative insoluble; or the carrier material may be treated with a solution, which may have a pH of 6 to 9, contaming both the starch derivative and the melamine-aldehyde precondensate; 5 to 20% of melamine-aldehyde precondensate based on the weight of the starch derivative may be used. The treated carrier may be dried at a temperature of 80 to 100‹C. The starch before hydrolysis may be gelatinized or non gelatinized, and may be corn, waxy maize, potato, sago, wheat, tapioca, or rice starch, starches modified by acids, enzymes or oxidants, dextrins, chemical derivatives of starch which retain their starch character, and 1 to 20% by weight of inorganic acid and 5 to 50% by weight of urea based on the weight of starch may be used in the hydrolysis thereof. The weight ratio of urea to inorganic acid may be from 1 to 8:1. The inorganic acid may be sulphamic, phosphoric, sulphuric, hydrochloric, or nitric acid, or a mixture thereof. The melamine-aldehyde precondansate may be a methylol derivative or formaldehyde resin of melamine or substituted melamine e.g. stearyl melamine, and may be an alkylated or partially alkylated melamine-aldehyde precondensate e.g. a methylated or butylated methylolmelamine. The treated carrier may be calendered and/or supercalendered.