Grades packaging paper

The paper machine in this exercise manufactures two-ply kraft liner board grade packaging paper using unbleached long-fibre kraft pulps. The refining operation of the stock approach system of the top ply comprised two 42 double-disc refiners... 

In addition, many grades of paper and paperboard are used in direct or indirect contact with foods. Thus, many mills only use paper chemicals that have been cleared for use by the U.S. Pood and Dmg Administration (PDA) (3), so that it is not necessary to segregate machine broke (off-grade paper and edge clippings that are reclaimed for their fiber value) and white water. Most of the chemicals discussed in this article are approved by the PDA for use in paper and paperboard that are intended for appHcations in food processing and packaging. However, there are various restrictions on both the specific functional uses and amounts of paper chemical additives which can be used, so the PDA status should be confirmed by the suppHer before use. 

These products are used on a number of grades hygiene papers, some liquid packaging grades, wall paper base, sack grades, etc. 

After the surface-sizing section, the paper is dried again by an array of steam-heated rolls (after-drying section) to a moisture content of 6-8%. After an additional smoothing step calendar grades like e.g. office papers and packaging papers are ready for use. 

The microcrystalline grades also vary much more widely than paraffins in their physical characteristics some are ductile and others are brittle or crumble easily. Both paraffin and microcrystalline waxes have wide uses in food packaging, paper coating, textile moisture proofing, candle-making, and cosmetics. Petrolatum is derived from heavy residual lube stock by propane dilution and filtering or centrifuging. It is microcrystalline in character and semi-solid at room temperature. 

Most membranes are made of porous cellulose acetate and are available in a range of porosities, from 0.22 pm to several micrometers. Sterilization and the complete removal of the smallest microorganisms (bacteria) requires the use of sterile membranes of porosities of 0.45 pm or less. Filter housings and clamps should be packaged in aluminum foil and then heavy-grade wrapping paper (butcher paper) prior to autoclaving and not opened until use. Alternatively, suppliers make disposable filter units that facilitate sterilization of small volumes of media. 

Mixed grades comprising always a mixture of various paper and board grades used for the production of packaging paper and board. 

Control of the serviceability of many grades of paper and board, e. g. milk/juice carton, packaging papers, wallpaper, printing writing papers, etc. 

A large number of grades of paper and board are available for packaging and are employed for many different purposes. 

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