Southern bleached softwood kraft

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Southern bleached softwood kraft (SBSK) is a wood pulp mainly produced in the southern USA. The main raw materials are slash pine, longleaf pine, shortleaf pine, loblolly pine and virginia pine. [1]

Contents

Properties

SBSK is produced from mixed fibre sources, but the main wood species of the pulp is dominating the properties. All have long fibres. Slash pine and longleaf pine have thick walled fibres and makes the pulp suitable for fluff pulp.

Applications

SBSK is used in fluff pulp, tissue paper, filter paper and mercerised pulp. It is used as reinforcement fibres when making paper or as raw material for kraft paper.

See also

Northern bleached softwood kraft

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Pulp (paper)

Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw material used in papermaking and the industrial production of other paper products.

Softwood

Softwood is wood from gymnosperm trees such as conifers. The term is opposed to hardwood, which is the wood from angiosperm trees.

Paperboard Thick paper-based material

Paperboard is a thick paper-based material. While there is no rigid differentiation between paper and paperboard, paperboard is generally thicker than paper and has certain superior attributes such as foldability and rigidity. According to ISO standards, paperboard is a paper with a grammage above 250 g/m2, but there are exceptions. Paperboard can be single- or multi-ply.

Pulpwood

Pulpwood is timber with the principal use of making wood pulp for paper production.

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Paper machine

A paper machine is an industrial machine which is used in the pulp and paper industry to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machine, which uses a moving woven mesh to create a continuous paper web by filtering out the fibres held in a paper stock and producing a continuously moving wet mat of fibre. This is dried in the machine to produce a strong paper web.

Kraft process

The kraft process (also known as kraft pulping or sulfate process) is a process for conversion of wood into wood pulp, which consists of almost pure cellulose fibers, the main component of paper. The kraft process entails treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na2S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose. The technology entails several steps, both mechanical and chemical. It is the dominant method for producing paper. In some situations, the process has been controversial because kraft plants can release odorous products and in some situations produce substantial liquid wastes.

Paper recycling

The recycling of paper is the process by which waste paper is turned into new paper products. It has a number of important benefits: It saves waste paper from occupying homes of people and producing methane as it breaks down. Because paper fibre contains carbon, recycling keeps the carbon locked up for longer and out of the atmosphere. Around two-thirds of all paper products in the US are now recovered and recycled, although it does not all become new paper. After repeated processing the fibres become too short for the production of new paper - this is why virgin fibre is frequently added to the pulp recipe.

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Pulp mill

A pulp mill is a manufacturing facility that converts wood chips or other plant fiber source into a thick fiber board which can be shipped to a paper mill for further processing. Pulp can be manufactured using mechanical, semi-chemical, or fully chemical methods. The finished product may be either bleached or non-bleached, depending on the customer requirements.

Kraft paper

Kraft paper or kraft is paper or paperboard (cardboard) produced from chemical pulp produced in the kraft process.

Cotton paper, also known as rag paper or rag stock paper, is made using a cotton linter or cotton from used cloth (rags) as the primary material. Important documents are often printed on cotton paper, because it is known to last many years without deterioration. Cotton paper is superior in both strength and durability to wood pulp-based paper, which may contain high concentrations of acids, and also absorbs ink or toner better. Different grades of cotton paper can be produced.

The sulfite process produces wood pulp that is almost pure cellulose fibers by treating wood chips with solutions of sulfite and bisulfite ions. These chemicals cleave the bonds between the cellulose and lignin components of the lignocellulose. A variety of sulfite/bisulfite salts are used, including sodium (Na+), calcium (Ca2+), potassium (K+), magnesium (Mg2+), and ammonium (NH4+). The lignin is converted to lignosulfonates, which are soluble and can be separated from the cellulose fibers. For the production of cellulose, the sulfite process competes with the Kraft process, which produces stronger fibers and is less environmentally costly.

Paper Thin material for writing, printing, etc.

Paper is a thin sheet material produced by mechanically and/or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distributed on the surface, followed by pressing and drying. Although paper was originally made in single sheets by hand, almost all is now made on large machines—some making reels 10 metres wide, running at 2,000 metres per minute and up to 600,000 tonnes a year. It is a versatile material with many uses, including printing, packaging, decorating, writing, cleaning, filter paper, wallpaper, book endpaper, conservation paper, laminated worktops, toilet tissue, currency and security paper and a number of industrial and construction processes.

Northern bleached softwood kraft (NBSK) is the paper industry's benchmark grade of pulp. Market NBSK is produced mainly in Canada and the Nordic countries. Some NBSK is also produced in north-western United States and in Russia. NBSK futures are traded on the Chicago Mercantile Exchange.

Dissolving pulp, also called dissolving cellulose, is bleached wood pulp or cotton linters that has a high cellulose content. It has special properties including a high level of brightness and uniform molecular-weight distribution. This pulp is manufactured for uses that require a high chemical purity, and particularly low hemicellulose content, since the chemically similar hemicellulose can interfere with subsequent processes. Dissolving pulp is so named because it is not made into paper, but dissolved either in a solvent or by derivatization into a homogeneous solution, which makes it completely chemically accessible and removes any remaining fibrous structure. Once dissolved, it can be spun into textile fibers, or chemically reacted to produce derivatized celluloses, such cellulose triacetate, a plastic-like material formed into fibers or films, or cellulose ethers such as methyl cellulose, used as a thickener.

Air-laid paper is a textile-like material categorized as a nonwoven fabric made from fluff pulp.

Fluff pulp is a type of chemical pulp made from long fibre softwoods. Important parameters for fluff pulp are bulk and water absorbency.

In industrial paper-making processes, organosolv is a pulping technique that uses an organic solvent to solubilise lignin and hemicellulose. It has been considered in the context of both pulp and paper manufacture and biorefining for subsequent conversion of cellulose to fuel ethanol. The process was invented by Theodor Kleinert in 1968 as an environmentally benign alternative to kraft pulping.

Bleached Chemi-ThermoMechanical Pulp (BCTMP) is a pulp product used by the paper industry as a less-expensive alternative for Northern Bleached Softwood Kraft (NBSK).

References

  1. Nanko, Hirko; Button, Allan; Hillman, Dave (2005). The World of Market Pulp. Appleton, WI, USA: WOMP, LLC. pp. 13–18. ISBN   0-615-13013-5.