Coated paper surface hardness

Alum has two prime uses. About two thirds of it is bought by the pulp and paper industry for coagulating and coating pulp fibers into a hard paper surface by reacting with small amounts of sodium carboxylates (soap) present. Aluminum salts of carboxylic acids are very gelatinous. 

Chem. Descrip. Difunctional epoxy acrylate oligomer Uses Film-former for epoxy resins in UV/EB-curable formulations, lithographic, screen, and metal deco printing inks, clear coatings for paper/ paperboard, wood, metal, and rigid plastic substrates Features Fast cure speed formulations show high surface hardness and gloss finish, exc. scuff and solv. resist, chars. 

Chem. Descrip. Aliphatic urethane diacrylate oligomer Uses Film-former for UV/EB-curable coatings and inks for paper/paper-board, plastic, and metal substrates base resin for screen printing inks Features Mod. cure response exc. solv. resist., surface hardness, flexibility, toughness... 

Uses Detergent, emulsifier, dispersant, wetting agent, stabilizer for laundry, household, textiles, hard-surface detergents, cosmetics, insecticides, paper, petroleum, paints food-contact coatings, paper, cellophane emulsifier in mfg. of food-contact articles defoamer in food-contact coatings ManufJDistrib. Aldrich DelCon... 

The functions of covers or coatings in soft nip calenders are twofold. The hard heated roll in the calender is either a chilled iron roll with a hard wear-resistant surface, or it is coated for even more improved wear resistance. The surface of the hard roll needs to be extremely smooth, as the roll surface is imprinted onto the paper surface. Since thermal energy must be transferred to the paper through the coating, its thermal conductivity and thickness are important... 

Uses Wetting agent, penetrant, dispersant for agrochemicals, hard surface cleaners, paints and coatings, paper and textile processing, pigment and wax/resin dispersion silicone emulsifier... 

Multivalent ions in starch dispersions, particularly those of aluminum, calcium, sulfate and oxalate, will induce retrogradation due to complexation or competition for water of hydration. The ions can be introduced by hard process water or accumulate by leaching from paper during surface sizing or coating. The destabilizing effect of ions follows the Schulze-Hardy rule. 

Calcium carbonate scale is the most common of these three forms of inorganic deposits. It has the appearance of a hard coating on the surfaces of the paper machine or a pulp system, usually discoloured by incorporation of small quantities of other material such as hgnin. 

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