Pulping processes, developers

Aloisture Absorbent Synthetic Paper. Processes for making a water absorbent synthetic paper with dimensional stabihty have been developed by several companies. In a process developed by Mitsubishi Rayon, acrylic fiber is insolubilized by hydra2ine and then hydroly2ed with sodium hydroxide. The paper, formed from 100 parts fiber and 200 parts pulp, has a water absorption 28 times its own weight (96). Processes for making hygroscopic fibers have also been reported in the patent Hterature. These fibers are used in moisture absorbing nonwovens for sanitary napkins, filters, and diapers. 

Pulp-like olefin fibers are produced by a high pressure spurting process developed by Hercules Inc. and Solvay, Inc. Polypropylene or polyethylene is dissolved in volatile solvents at high temperature and pressure. After the solution is released, the solvent is volatilised, and the polymer expands into a highly fluffed, pulp-like product. Additives are included to modify the surface characteristics of the pulp. Uses include felted fabrics, substitution in whole or in part for wood pulp in papermaking, and replacement of asbestos in reinforcing appHcations (56). 

Dry-Laid Pulp. A principal objective of using air to form webs from natural and synthetic fiber pulps is to produce relatively lofty, porous stmctures from short fibers, without using water. Early technical developments in air-laid pulp processing were made by Kroyer in Denmark. 

Fiber Analysis. Paper may be composed of one or several types of fibers, eg, animal, vegetable, mineral, and synthetic (see Eibers). Paper is generally composed of woody vegetable fibers obtained from coniferous (softwood) and deciduous (hardwood) trees. QuaUtative and quantitative methods have been developed to determine the fibrous constituents in a sheet of paper (see TAPPI T401). However, the proliferation in the number and types of pulping processes used have made the analysis of paper a much more complex problem. Comprehensive reviews of the methods are given in References 20 and 23. 

NSSC Pulping. The characteristics of semichemical pulps are especially suited to the production of cormgated medium, which is the raw material for the fluted center ply of cormgated boxes. Neutral sulfite semichemical pulping was developed specifically as a semichemical process for cormgation medium and lends itself to small mills having minimal capital investment. For many years, this was the only semichemical pulping process. 

The raw materials for the manufacture of soap, the alkali salts of saturated and unsaturated C10-C20 carboxylic acids, are natural fats and fatty oils, especially tallow oil and other animal fats (lard), coconut oil, palm kernel oil, peanut oil, and even olive oil. In addition, the tall oil fatty acids, which are obtained in the kraft pulping process, are used for soap production. A typical formulation of fats for the manufacture of soap contains 80-90% tallow oil and 10-20% coconut oil [2]. For the manufacture of soft soaps, the potassium salts of fatty acids are used, as are linseed oil, soybean oil, and cottonseed oil acids. High-quality soap can only be produced by high-quality fats, independent of the soap being produced by saponification of the natural fat with caustic soda solution or by neutralization of distilled fatty acids, obtained by hydrolysis of fats, with soda or caustic soda solutions. Fatty acids produced by paraffin wax oxidation are of inferior quality due to a high content of unwanted byproducts. Therefore in industrially developed countries these fatty acids are not used for the manufacture of soap. This now seems to be true as well for the developing countries. 

DegOX [Degussa oxidation] A pulp-bleaching process developed by Degussa. The active species is peroxomonosulfuric acid (Caro s acid). The first full-scale commercial trial was held in 1994. 

GreenOx A pulp-bleaching process developed by Kemira in Finland. 

MILOX [Milieu oxidative] A wood-pulping and bleaching process. Wood chips are treated with hydrogen peroxide and formic acid in a three-stage process. Developed by the Finnish Pulp and Paper Research Institute (KCL) and Kemira. Piloted at Oulu, Finland in 1991. 

Oxypro (2) A family of pulp-bleaching processes developed by Air Products and Chemicals. Piloted in 1995 at Pittsfield, MA. Oxypro 0R is for processing mixed office waste papers it uses molecular oxygen, optionally hydrogen peroxide, sodium hydroxide, and a stabilizer. First commercialized in Scotland in 1994. 

Continuous Methods for Manufacturing Nitrocellulose. Several methods are known, of which the Dietzsch process developed during WWII in Germany is briefly described here under Combustible and Consumable Cartridge Cases. This method combines vapor-phase and liquid-phase nitration processes. The Japanese used during WWII a continuous liquid-phase method of nitration of paper pulp, which was in the form of a sheet... 

Another important event could have been chosen on which to base a centennial—the invention of the sulfite pulping process by the Tilghman brothers in Philadelphia. Although dated as 1866 when a British patent for the process was issued, successful laboratory experiments had been made in 1865. In their attempts to adapt the new method to commercial scale, the Tilghmans tried to develop a continuous process but unfortunately could not solve the technical problems involved. A few years later, at the beginning of the 1870 s, experiments on sulfite pulping were taken up in several places in Europe, and in 1874 the first sulfite pulp was produced commercially by C. D. Ekman in a Swedish mill. 

The oxidative procedures involve alkaline nitrobenzene, nitric acid, and molecular oxygen under acidic, neutral, and mildly alkaline conditions. Dilute nitric acid solutions were used under the conditions of the nitric acid pulping process. The analytical procedures which have been developed include gas-liquid chromatography (GLC) for quantitative analy-... 

Few thermomechanical pulping processes existing today use the original Mason process now that more streamlined operations have evolved but all stem from Mason s development. 

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