Classifications

• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
  • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
  • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
  • B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
  • B27N3/08—Moulding or pressing
  • B27N3/18—Auxiliary operations, e.g. preheating, humidifying, cutting-off
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F9/00—Complete machines for making continuous webs of paper

Definitions

• This invention relates to a process for the production of a fibrous sheet material mainly consisting of cellulosic fibres.
• fibres are laid down dry, or practically dry, on the wire, e.g. by using the apparatus described in US patent No. 3,575,749 and in patents in other countries.
• Formica products are made industrially using the air-laying process.
• the air-laying process has advantages over the wet-laying process regarding energy, space for equipment, pollution, manpower and plant cost, and it would be extremely profitable for the paper industry if the two processes could be combined.
• the wet process normally requires the use of 100 times more water than fibres.
• the dry process has the disadvantage that it does not produce hydrogen bonds, which is a necessity for the manufacture of most types of paper.
• the process of the invention comprises depositing a layer of defibrated cellulosic material onto a continuously moving support, adding to said layer an aqueous medium in an amount of from 0.3 to 1 part by weight of water per part by weight of the defibrated material causing hydrogen bonds (partly or totally) to be established within the fibrous layer, and processing the fibrous layer to form the desired fibrous sheet material.
• Fig. 1 is a side view of the apparatus according to the present invention.
• a particularly preferred embodiment of the invention is suitable for use in connection with a conventional wet-laying paper machine and the invention will now be described in further detail with reference to such a machine. It should be understood however, that the advantages obtained by the process of the invention can also be achieved by using an apparatus specifically designed for the production of fibrous sheet materials by said process.
• the head-box, or other wet-laying equipment normally used for uniformly distributing the fibres on the forming wire is bypassed, closed down or replaced by an air-laying head, preferably placed in such a manner that there is suction underneath the wire.
• This suction might be obtained through the use of suction equipment normally employed in the wet process, or another simpler vacuum installation 4.
• the defibrated fibres can be distributed in a dry state or almost dry state (by means of said dry-forming distributor which thus functions as an "air-laying head- box").
• the aqueous solution or water is preferably supplied to the fibrous layer with the vacuum still maintained under the wire. This suction maintains a subatmospheric pressure in a zone below this supply zone to improve the penetration of the aqueous solution into the fibrous layer.
• the amount of water to be supplied to the dry-laid paper is determined by taking into account the amount of water necessary for the required degree of hydrogen bonding. According to the invention, only a small fraction of the quantity of water normally necessary for the wet-laying process is added to the air-laid fibrous layer on the wire, to control the degree of hydrogen bonding. Thus, a fibrous felt is obtained suitable for use in the manufacture of practically all paper products including soft products, writing and printing paper or board products.
• Hydrogen bond is produced by adding less than one part water per part fibre.
• the aqueous solution is preferably added in an amount sufficient to obtain a water content in the fibrous layer of from about 0.4 to about 0.6 and more preferably for many products about 0.5 parts by weight of water per part by weight of fibrous material.
• the amount of water added to the dry-laid paper is thus far below the vast amounts used in a wet-laying process.
• the paper-felt is normally passed onto the normal finishing equipment generally used in the wet paper industry.
• binders because the process takes advantage of the hydrogen bonding without creating excessive hydrogen bonding.
• paper (even with a weight per m2 of 30-100g) can be made as soft as required by controlling the amount of water supplied after the fibres are air-laid.
• the dry-laid fibrous layer has a three dimensional structure whereas a fibrous layer prepared by wet-laying mostly is orientated two-dimensionally.
• the invention also relates to an apparatus for carrying out the process described above.
• This apparatus comprises a fibre distributor 1 mounted above a continously movable permeable support 2 with supporting rollers 3, so as to form a layer 7 of a defibrated cellulosic material on said movable permeable support 2.
• the apparatus also comprises means 5 for adding an aqueous solution to said layer in an amount of 0.3 to 1.0 part by weight of water per part by weight of the defibrated material.
• a dry-laying fibre distributor 1 is mounted above the foraminous wire of a paper machine based on wet-laying, whereas the finishing of the paper product 7 takes place by conventional creping cylinder 6.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Wood Science & Technology (AREA)
• Forests & Forestry (AREA)
• Textile Engineering (AREA)
• Paper (AREA)
• Nonwoven Fabrics (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=22497824

Family Applications (1)

Country Status (6)

Cited By (1)

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Family Cites Families (2)

• 1994
  • 1994-10-28 DE DE69412846T patent/DE69412846T2/de not_active Expired - Fee Related
  • 1994-10-28 AT AT95915047T patent/ATE170240T1/de not_active IP Right Cessation
  • 1994-10-28 AU AU79901/94A patent/AU7990194A/en not_active Abandoned
  • 1994-10-28 EP EP95915047A patent/EP0725851B1/de not_active Expired - Lifetime
  • 1994-10-28 CA CA002175229A patent/CA2175229C/en not_active Expired - Fee Related
  • 1994-10-28 WO PCT/DK1994/000398 patent/WO1995012020A1/en active IP Right Grant

Non-Patent Citations (1)

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