GB341542A - Improvements in pulps comprising fibrous material and heatplastic waterproofing material, and in the method for manufacturing the same - Google Patents

Abstract

341,542. Waterproof paper and board. RICHARDSON CO., Wyoming Avenue, Lockland, Ohio, U..S.A. Oct. 18, 1929, No. 31746. Convention date, Nov. I, 1928. [Class 96.] A heat plastic waterproofing material such as bitumen, rubber composition, or synthetic resin is incorporated into paper pulp without the use of an emulsifying agent by distributing it whilst in a molten or liquid form, in the absence of sufficient water as would form a circulating medium. Other suitable substances are asphalt, waxes, gums, partially oxidized drying oils, and blown oils ; the process also provides a method for sizing paper with sodium silicate, glue and other waterproofing agents. The product obtained can be used as roofing felt. Mineral fillers can be used together with the binders and sizes. In an example wet sheets of paper or pulp are intimately mixed with a fluid or semi-solid binder in a kneading machine such as the Werner-Pfleiderer mixer, the temperature being kept sufficiently high to prevent solidification of the bitumen or other material. This preliminary mixing operation results in a discontinuous mass of fibre and bitumen, and providing the fibres are kept moist, it can readily be broken down to a water pulp by the addition of water. The mass is transferred to a paper mill beater where the nodules or lumps are combed out and a smooth uniform pulp obtained. If desired, the pulp may be passed through one or more refining engines or Jordans, and thence to the paper-making machine. Hot calendering or pressing is advantageous to develop the full strength of the finished sheets,