Лако-красочные материалы — производство

Oxidized starch is commonly obtained by aqueous alkaline hypochlorite treatment. A starch suspension at pH 8-10 is treated with hypochlorite (5-10% Cl based on starch) for long enough to produce the desired viscosity. Acid is liberated during the reaction, so base must be added to maintain the pH for optimum reactivity. The resultant starch contains […]

Acid modification of starch is achieved by heating the starch to 49-54° C with small amounts of aqueous mineral acid, followed by neutralization with base. The acid acts mainly on the amorphous regions of the starch granules, leaving the x-ray and birefrin­gence patterns of the crystalline regions essentially unchanged. Dried acid-modified starch appears very similar […]

Starch must be modified before it can be used as an adhesive. Methods for opening the starch granules include heating, alkali treatment, acid treatment, and oxidation. 1. Heat Treatment The simplest method of breaking up starch granules is well known to the cook. To thicken a sauce, cornstarch must be heated. During the heating process, […]

Like cellulose, starch is a naturally occurring polymer of glucose. It differs from cellulose in two significant aspects: the glucose rings are in the a-D configuration rather than the (3-d configuration, and starch can be differentiated into two types of polymers. One poly­mer, amylose consists of a-D-anhydroglucopyranose monomeric units combined linearly through 1-4 linkages with […]

Starch is produced by plants as a way to store the chemical energy that they produce during photosynthesis. Starch is found primarily in the seeds, fruits, tubers, and stem pith of plants, most notably corn, wheat, rice, sago, and potatoes. In 1985 alone, more than 1.6 billion kilograms of starch was used in applications involving […]

Hydroxyethyl cellulose with an MS value greater than 1.6 is soluble in hot or cold water; with an MS value of 2.3-2.6, it is soluble in organic solvents. HEC forms oil- and grease — resistant films that retain clarity over time. It is used as an adhesive in billboards, corru­gated board, plywood, and wallpaper, and […]

Carboxymethyl cellulose, generally as its sodium salt, is the most widely used cellulose ether. CMC is water soluble with a DS of 0.4-1.2 in common applications. It was origin­ally used as a replacement for natural gums in adhesives, but it has since developed many uses of its own. Sodium carboxymethyl cellulose is readily water soluble […]

In contrast to methyl cellulose, ethyl cellulose is commonly prepared in its organic soluble state with a DS of 2.3-2.6. Films of ethyl cellulose are thermoplastic, and they resist alkali and salts. Because of their organic solubility, the films tend to swell very little in the presence of water. The resistance of ethyl cellulose to […]

Methyl cellulose with a low DS (0.4-0.6) is soluble in dilute aqueous sodium hydroxide. As substitution is increased, the methyl cellulose becomes soluble in water (DS 1.3-2.6), then in organic solvents (DS 2.4-2.6). The most commonly used derivatives have a DS of 1.2­2.0. which results in cold-water solubility and solution stability for pH 2-12. Upon […]

Use of the mixed ether cellulose acetate butyrate helps to overcome some difficulties associated with using cellulose acetate as an adhesive. CAB is soluble in a greater range of organic solvents than is the pure acetate, and it is more compatible with common plasticizers. It can be applied either as a hot-melt adhesive or in […]