| 摘要 |
1,221,952. Papermaking; electrostatic deposition. RANSBURGH ELECTRO-COATING CORP. 5 Jan., 1968 [5 Jan., 1967], No. 890/68. Headings D1L, D2A and D2B. Fibrous cellulosic sheet material, e.g. paper or paper-board, as a wet web is sized by electrostatically charging dry particles of a water-sensitive bonding material to deposit the particles on the web, land then dewaitering the web. The waiter-sensitive bonding material is a natural resin such as rosin, hydrogenated rosin or partial esters of rosin; proteins, such as zein, that are soluble either in water or in dilute alkali; ester gums; natural gums such as gum arabic, agar-agar or Irish moss; synthetic resins such as polyvinyl alcohol and acrylic ester carboxylic acid copolymers; or carboxymethylcellulose. The use of starch is excluded, since it is within the scope of Specification 1,221,951. Those bonding materials, including rosin and its partial esters, that have free carboxylic acid groups may be saponified, e.g. on their surfaces. When saponified rosins are used, alum may be included in the furnish. Other particulate materials such as clay may be applied at the same time as the bonding materials. Very small amounts of bonding material may be applied by this technique, which can be carried out in the apparatus disclosed in Specification 1,221,951. |
