Pulping, semi-chemical

In case that corrugated base papers are not any more produced from recycled paper, as it is typical for testliner and medium in Germany, virgin fibres would have to be used. The corresponding paper grades as kraftliner would be produced from kraft pulp and fluting from semi-chemical pulp. For the simplified calculation of the required wood demand for the fibres, an average process yield of 60% (kraft pulp = 50%, semi-chemical pulp = 70%) is used. The substitution of the... 

Semi-chemical pulp contaminated with micro-organisms and incubated at 60°C produces a hydrogen-containing gas. A gas-phase explosion in a pulp storage tower was attributed to static ignition of this gas admixed with air. 

Semi chemical pulps are usually prepared by the neutral sulfite semichemical (NSSC) process, although modifications of the full chemical processes can be used. Active pulping chemicals are (in the sodium-base NSSC process) sodium sulfite buffered with sodium bicarbonate (pH 7,0-9.0) and (in the ammonium-base NSSC process) ammonium sulfite with ammonium hydroxide used as a buffer. Defiberization is usually accomplished by attrition mills of the disk type. 

Most label papers are chemical pulp, with additives, only. Most box boards are layers of mechanical or semi-chemical pulps with chemical pulps on the face and sometimes the back facings. Corrugated will probably, today, be nearly all recycled material, whereas unbleached semi-chem would have been used in the past for the corrugated medium. Any Kraft facing paper will probably still be 80-90% virgin Kraft pulp in make-up. 

Pulp type Mechanical pulp sew TMP CTMP CMP Semi- chemical pulp Chemical pulp... 

Paper and board are composed of cellulose obtained by the mechanical or semi-chemical treatment of vegetable fibers (pulp) derived from various sources like wood, hemp, cotton, etc. In some cases waste and regenerated paper is used. 

Neutral Sulfite Pulping Neutral sulfite pulping is mainly used for the production of high-yield pulps from hardwoods. The process is often named the "NSSC" (Neutral Sulfite Semi-Chemical) process. The wood is delignified only partially and mechanical fiberization is thus required. The prod-... 

In this case, the paper machine manufactures flat sack kraft paper from a blend of virgin pine (long-fibre) kraft pulp with typical Kappa range of 55-65 and eucalyptus (short-fibre) neutral sulfite semi-chemical (NSSC) pulp. The most important properties for sack papers are stretch and tensile energy absorption (TEA) in both cross direction (CD) and machine direction (MD). The major problems with the quality of sack papers currently made on this machine were poor stretch and TEA profile in fhe cross direction as shown in... 

Pulping (mechanical, chemical, semi-chemical, and deinking) Pulp Washing and Screening Stock Preparation Papermaking... 

The dominant process of semiwith sodium or ammonium sulfite as the digestion chemicals. The pulp yield is in the range 70-80% depending on the wood species, most commonly hardwood species like birch, beech, maple, oak and eucalyptus. This pulp is used for fluting production - often as the sole component in furnish. 

Pulps have since been made by various chemical processes, covering the full pH range from acid to neutral to alkaline. Each pulping method produces characteristic pulp properties, depending on the type of wood used, and each pulp type lends itself to a different end use. The most widely used chemical cooking process in North America today is the alkaline kraft process . The kraft process was invented in 1884, and the first U.S. kraft mill started production in 1909. As will be detailed later, semi-chemical, chemi-mechanical, and non-suUur cooking processes are also used. These methods are often considered more environmentally friendly than some of the older processes. 

Wood pulp is made by several processes ranging from mechanical to semi-chemical to fully chemical methods. Each pulping process produces a pulp with properties imique to itself. 

The production of paper and paperboard in 1995 was 278 X 10 mt worldwide. Roughly a quarter of the fiber material used derives from mechanical or semi-mechanical wood pulp, another quarter from the use of waste paper, while the rest is bleached or unbleached chemical pulp. 

RP-HPLC methods have been frequently applied for the investigation of various chemical, biochemical and biophysical processes in in vitro model systems. Thus, the separation of new compounds achieved by enzymatic oxidation of phloridzin was carried out by semi-preparative RP-HPLC. Phloridzin was incubated with a polyphenol oxidase prepared from apple pulp for 6h at 30°C under air agitation. After incubation the suspension was filtered, stabilized by NaF and injected into the RP-HPLC column using diluted acetic acid-ACN gradient. The new compounds were isolated and identified by NMR and MA techniques. The proposed mechanism of the formation of new phloridzin derivatives 3 and 4 is shown in Fig. 2.159. The results illustrate that RP-HPLC can be successfully used for the study of enzymatic processes in model systems [331],... 

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