Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
  • D21H11/12—Pulp from non-woody plants or crops, e.g. cotton, flax, straw, bagasse
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/18—Reinforcing agents

Definitions

• the invention relates to a method of improving the internal bond strength of paper and paper products.
• the internal bond strength refers to the ability of paper to resist stresses in the thickness direction of the paper. When the Z direction strength of paper/cardboard is exceeded, the structure of the paper breaks down even if the surface remained intact.
• the internal bond strength is a particularly important property in the printing of paper products and cardboards.
• the internal bond strength may be measured by various physical tests, such as a Scott bond test, according to the T 569 pm-00 standard.
• the internal bond strength of paper products may be improved in various ways, such as by paying attention to web formation, wet pressing and fibre orientation or by improving the strength of fibre bonding e.g. by adding various chemical fillers or additives or by refining the pulp.
• An object of the invention is thus to provide a method of improving the internal bond strength of paper and other paper products in a re- peatable manner.
• the object of the invention is achieved by a method which is characterized by what is stated in the independent claim. Preferred embodiments of the invention are disclosed in the dependent claims.
• the invention relates to a method of improving the internal bond strength of paper manufactured from wood pulp by adding a certain type of non-wood pulp composition to the wood pulp.
• parenchymatous cells refer to parenchymatous cells and the like of non-wood pulp.
• Epidermis cells refer to epidermis cells and the like of non- wood pulp.
• Accept and Accept fraction refer to a fraction that has passed through a sieve or a screen or that has been separated by a hydrocyc- lone as a hydrocyclone top product.
• Reject and "reject fraction” refer to a fraction that has been retained on a sieve or screen or in a hydrocyclone as a hydrocyclone bottom product.
• the invention relates to a method of improving the internal bond strength of paper manufactured from wood pulp by adding to the wood pulp a non-wood pulp composition having the following properties: it contains fibres whose length/width ratio lies within a range of 40 to 150, parenchymatous cells whose length/width ratio lies within a range of 1 to 20, and epidermis cells whose length/width ratio lies within a range of 1 to 20, and
• the amount of the fibres is at least 25%, preferably at least 33%, the amount of the parenchymatous cells is 20 to 35%, and the amount of the epidermis cells is 10 to 25% of the total non-wood pulp composition, as calculated by weight.
• the amount of the parenchymatous cells in the composition is larger than that of the epidermis cells.
• the non-wood pulp composition also contains small amounts of other common cell types of non-wood pulp, such as various vessel elements, tracheids, cork cells, and hair cells.
• the proportion of non-wood pulp composition to be added is 5 to 35%, preferably 5 to 25%, most preferably 25 to 35%, as calculated from the wood pulp.
• the non-wood pulp composition may be added to the wood pulp at any suitable stage prior to paper manufacture. It may be added to bleached or unbleached pulp.
• the non-wood pulp composition to be added is produced by fractionating chemical non-wood pulp.
• the fractionation may be carried out using fractionation based e.g. on screening, classification or pressure difference.
• Suitable industrial devices for these include screens, sieves, such as pressure sieves, and hydrocyclones (vortex cleaners).
• the pressure sieve may be e.g. an aperture sieve.
• fractionation is carried out using hydrocyclone fractionation.
• the hydrocyclone fractionation is carried out by a hydrocyclone whose diameter is 30 to 70 mm, e.g. 30 to 50 mm or 50 to 70 mm.
• fractionation is carried out using pressure sieve fractionation.
• the aperture size of the pressure sieve is preferably within a range of 0. 5 to 0.6 mm.
• a combination of pressure sieve fractionation and hydrocyclone fractionation is used.
• pressure sieve fractionation into accept and reject is carried out, whereafter the accept is further fractionated into accept and reject by using a hydrocyclone.
• the accept separated from the pressure sieve fractionation accept by the hydrocyclone is recovered and added to the wood pulp.
• the accept separated from the pressure sieve fractionation reject by the hydrocyclone is recovered and added to the wood pulp.
• the pressure sieve fractionation is preferably carried out using a pressure sieve whose aperture size is 0.15 to 0.6 mm.
• the fractionation of the accept obtained from the pressure sieve fractionation is preferably carried out using a hydrocyclone whose diameter is 30 to 50 mm.
• the fractionation of the reject obtained from the pressure sieve fractionation is preferably carried out using a hydrocyclone whose diameter is 50 to 70 mm.
• the accept separated from the pressure sieve reject by a hydrocyclone may be used for improving the internal bond strength, since said fraction has no effect on the drainability of the pulp.
• the non-wood pulp composition is added to the wood pulp unrefined.
• the non-wood pulp composition is not refined together with the wood pulp, either.
• the invention relates to a method of improving the internal bond strength of paper made from wood pulp by adding to the wood pulp a non-wood pulp composition obtained by fractionating the non-wood pulp by a hydrocyclone whose diameter is 30 to 70 mm, by recovering the hydrocyclone accept, and by adding the hydrocyclone accept to the wood pulp in an amount of 5 to 35%, preferably 15 to 25%, most preferably 25 to 35%, as calculated from the wood pulp.
• the invention relates to a method of improving the internal bond strength of paper made from wood pulp by adding to the wood pulp a non-wood pulp composition obtained by a method comprising the following steps of:
• the flow rate in the hydrocyclone fractionation of the pressure sieve accept is within a range of 1.2 to 1.5 l/s.
• the invention relates to a method of improving the internal bond strength of paper made from wood pulp by adding to the pulp a non-wood pulp composition obtained by a method comprising the following steps of:
• the flow rate in the hydrocyclone fractionation of the pressure sieve reject is within a range of 1.8 to 2.2 l/s.
• non-wood pulp refers to pulp made from herbaceous plant fibres, bast fibres, leaf fibres or fruit seed fibres.
• useful herbaceous-plant-based fibres include straw, e.g. cereal straw (wheat, rye, oat, barley, rice, com), reeds, e.g. reed canary-grass, common reed, paper reed, sugar cane or bagasse, and bamboo, as well as grasses, e.g. esparto, sabai and lemon grass.
• bast fibres include flax, such as stems of common flax and stems of oil flax, hemp, east india hemp, kenaf, jute, ramie, paper mulberry tree, gambi fibre, and mitsumata fibre.
• leaf fibres include manilla hemp and sisal.
• fruit seed fibres include cotton seed hair and cotton linter fibres, kapok, and coconut fibre.
• Herbaceous plants growing in Finland and useful in the present invention include common reed, reed canary-grass, timothy, cock's-foot, yellow melilot, awnless brome, red fescue, white melilot, red clover, goat's rue, and medick.
• pulp manufactured from fibres of herbaceous plants such as straw cellulose pulp
• pulp manufactured from annual herbaceous plants is used.
• pulp manufactured from perennial non-wood plants is used.
• agricultural waste material including e.g. the aforementioned cereal straw, may also be used.
• the non-wood pulp may be pulp manufactured by any chemical methods, such as a sulphate, sulphite or soda method.
• the pulp may also be pulp manufactured by solvent-based methods, such as formic-acid- based and/or acetic-acid-based, alcohol-based or ionic methods.
• the pulp may be bleached or unbleached pulp.
• the wood pulp to which the non-wood pulp is added may be any chemical or mechanical softwood or hardwood pulp, such as pine, spruce, birch, eucalyptus, acacia, and aspen pulp or a mixture of any one thereof.
• the pulp may also be recycled pulp, possibly mixed with any one of the aforementioned pulps.
• Paper or other paper products is/are manufactured from mixed pulp obtained according the invention by employing conventional methods.
• the paper and paper products may be any paper products, including cardboard.
• the present invention is suitable for the manufacture of printing papers and coated papers, such as magazine papers of different types.
• the invention further relates to manufacture of paper pulp by adding the above-described non-wood pulp composition to wood pulp. Preferred embodiments of this aspect are the same as those disclosed above.
• the invention also relates to manufacture of paper and other paper products by using the thus obtained mixed pulp containing wood pulp and the above- described non-wood pulp composition.
• the invention also relates to a use of the above-described non-wood pulp composition for manufacturing paper pulp, paper, and other paper products. Preferred embodiments of this aspect are the same as those disclosed above.
• wheat straw pulp was fractionated by a fine pressure sieve (aperture size 0.2 mm) into two fractions, i.e. into accept, which was the fine fraction passed through the pressure sieve, and into reject, which did not pass through the pressure sieve.
• the pressure sieve accept was divided by a hydrocyclone (diameter about 40 mm ja flow rate 1.4 l/s) into accept (PS accept ⁇ HC accept) and reject (PS accept ⁇ HC reject), and the pressure sieve reject was divided by a hydrocyclone (diameter about 60 mm ja flow rate 2.0 l/s) into accept (PS reject ⁇ HC accept) and reject (PS reject ⁇ HC reject).
• Table 1 shows weight proportions of said pulp fractions on the total pulp and Table 2 shows cell type compositions.
• the cell types were determined in accordance with the ISO 9184-1 -7 standard by using Fiber Atlas by Marja-Sisko llvessalo-Pfaffli in the identification. More than 5 000 cells were calculated from each sample.
• the cell type calculation revealed clear differences between the pulp fractions.
• the pressure sieve accept contained clearly less actual fibres and more of both parenchymatous cells and epidermis cells than the pressure sieve reject.
• the most vessel elements were found in the pressure sieve reject that had ended up in the hydrocyclone accept.
• the most parenchymatous and epidermis cells were found in the pressure sieve accept that had ended up in the hydrocyclone reject.
• Half of the fraction that had ended up in both the pressure sieve and the hydrocyclone accept was comprised of fine fibres, and the fraction also contained considerable amounts of parenchymatous cells and epidermis cells.
• the hydrocyclone affected the fractionation of the pressure sieve accept such that the hydrocyclone accept contained relatively more fibres than the reject, whereas the largest fraction of the reject consisted of epidermis cells.
• epidermis cells width 11 to 21 pm and length 120 to 220 pm
• parenchymatous cells width 20 to 1 10 pm and length 40 to 300 pm
• Wheat straw pulp was fractionated according to Example 1. Eucalyptus pulp manufactured by a sulphate method was refined to a refining degree required by typical fine paper manufacture (SR 27.5). 10% of the proportion of eucalyptus cellulose was replaced with wheat straw cellulose or wheat straw cellulose fractions and, in addition, in one of these fractions (PS accept ⁇ HC accept) 30%. Thus, at one test point, the wheat straw cellulose was used as such while at other test points different pulp fractions were used.
• the internal bond strength of the original pulp is weaker than that of any other combination, i.e. the internal bond strength may be improved by changing the original pulp composition.
• the greatest internal bond strength is achieved by using a double accept, i.e. a fraction which has passed through both a pressure sieve and a hydrocyclone (PSaHCa fraction). (No result from a test point of the 100% PSaHCa fraction is provided because the internal bond strength of paper made from said fraction was too great to be determined by the device in question).

Landscapes

• Paper (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=41263536

Family Applications (1)

Country Status (3)

Cited By (2)

Citations (1)

• 2009
  • 2009-10-30 FI FI20096122A patent/FI122075B/sv not_active IP Right Cessation
• 2010
  • 2010-10-21 TW TW099135961A patent/TW201118215A/zh unknown
  • 2010-10-22 WO PCT/FI2010/050830 patent/WO2011051556A1/en active Application Filing

Patent Citations (1)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events