Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F7/00—Other details of machines for making continuous webs of paper
  • D21F7/08—Felts
  • D21F7/083—Multi-layer felts

Definitions

• the invention concerns papermaking machine and like clothing, and has more particular, though not exclusive, reference to felts for use in the press-sections of papermaking machines, board-making machines, asbestos cement sheet-making machines and the like. STATE OF THE ART
• the batt in this latter style of felt comprises some 2/3 of the weight of the finished felt, whereas with a spun yarn base, the batt would typically comprise some 1/3 of the weight of the finished felt.
• the use of a greater weight of batt has made it particularly practical also to make felts with a different batt blend in the centre of the felt sandwiched between the mesh base and the surface batt.
• the surface batt will typically incorporate fibres similar in diameter to surface fibres used when a single batt blend is employed - generally in the range from 6 denier to 15 denier - whereas the batt fibres sandwiched between the base and the surface batt would be coarser and in the range from 15 to 80 denier.
• a typical felt with a monofilament mesh base would have 10 denier fibre in the surface batt and 40 denier fibre between the surface and the base, the objective of the coarser felt centre being to allow the easier passage of filling materials and to impart extra resilience due to the more springy nature of the thicker fibres.
• the increased batt content of the felts with monofil base fabrics has caused problems because it is more difficult to produce a sufficiently regular batt of fibres than it is to produce a regular woven structure.
• the difficulty in producing a regular batt of fibres increases with the coarseness of the fibres. There is, therefore, more tendency for press bumping to take place in demanding applications when employing a lighter weight base fabric with a greater batt weight, although the water removal properties and their inherent facility for keeping clean make felts with coarse denier fibres sandwiched between the surface fibres and the base fabric particularly acceptable for a wide range of papermaking applications.
• the primary object of the invention is to provide a felt wherein the advantages arising from the presence of coarse denier fibres in the centre of the felt are preserved even in the context of the more demanding presses and the need, in such context, for increased regularity in order to cope with the very high specific line pressures, although the invention is by no means confined to felts for use in connection with such demanding conditions.
• a base fabric for use in the manufacture of a batt-on-base type papermaker's felt, the said base fabric comprising a coherent base structure and a layer of substantially twist-free multifilament tow formed integrally therewith and provided at a face thereof to define an outer surface of the said fabric.
• a papermaker's felt comprising a coherent base fabric and a fibrous batt needled to such fabric is characterised in that that face of the base fabric to which the batt is applied is defined by substantially twist-free multifilament tow, the said tow being embodied in the base fabric during the formation of such fabric.
• the method of producing a papermaker's felt of the batt-on-base type characterise by the step of incorporating a layer of substantially twist-free multifilament tow in the base fabric during the manufacture thereof, the said multifilament tow existing at and defining an outer surface of the base fabric and the batt being needled to the said outer surface.
• the base fabric will usually comprise a woven structure in which the tow is embodied as an integral part thereof.
• the tow is woven into the surface of a base cloth in such a way that it can spread so as substantially to cover the surface of the base fabric.
• Coarse filaments introduced as tow at the face of a woven base cloth can be much more regularly arranged than can fibres of similar diameter be prepared into a batt and then needled into the surface of a base fabric.
• the base yarns in a conventional monofilament base do not lead themselves to the easy attachment of batt fibres by needling, the provision of an even layer of coarse filaments at the surface of the base fabric improves the facility with which a batt may be attached to that surface by needling.
• a base fabric containing yarns of twisted and/or single monofilaments in the intended machine and the cross-machine directions of the papermaking machine and incorporating in its surface and substantially covering its surface a layer of virtually twistless tow containing individual filaments of 40 denier will weigh about 580 g/m 2 .
• the total felt weight will be around 1300g/m 2 .
• the weight of the coarse continuous filamentary tow will not be less than 100 g/m 2 of finished felt, whilst the weight of the woven base fabric will comprise not less than 45% by weight of the finished felt.
• the components of the base fabric additional to the continuous filamentary tow are monofilaments of not less than 0.12mm average diameter, which monofilaments may or may not be twisted together.
• the coarse filaments will be woven into the surface of the base fabric in alignment with the intended running or machine direction of the felt on the papermaking machine, although the invention is not limited to such disposition of the coarse filaments in that the benefits of the invention are thought likely to arise from the inclusion of filamentary tow in either or both of the machine and cross-machine directions of the felt for the subsequent attachment thereto of a batt of filamentary material.
• the layer of surface fibres needled to the base fabric will usually comprise fibres averaging between 6 and 18 denier, and preferably averaging approximately 10 denier, although coarser fibres may be used if specific circumstances require.
• Fig. 1 is a cross-section taken in the running, or machine, direction of a base fabric constructed in accordance with the invention
• Fig. 2 is a cross-section of the base fabric shown in Fig. 1 taken in the cross-machine direction; and Fig. 3 is a view corresponding to Fig. 1, and shows the base fabric of Figs. 1 and 2 as embodied in a papermaker's press felt.
• a base fabric for use in the production of a press-felt for use in the press-section of a papermaking machine comprises a semi-duplex weave structure of which one machine direction layer 11 comprises 22 threads per inch of continuous filamentary tow 12 each of some 2400 denier in which the individual filaments are of 40 denier, while the other machine direction layer 13 comprises 22 threads per inch of 0.20 mm diameter nylon monofilament yarns 14 twisted two-ply and then three-ply.
• the cross-machine direction yarns 15 are 0.20 mm diameter nylon monofilaments twisted two-ply and again two-ply and spaced at 21 threads per inch.
• the woven base fabric 11 is subjected to a needling process in order to attach to its tow-faced side a batt 16 (see Fig. 3) of 10 denier nylon fibres which form the surface of the felt.
• the felt is finished by washing, drying and heat-setting following which it comprises
• the machine direction layer 11 comprises 20 threads per inch of continuous filamentary tow 12 each of some 4800 denier in which the individual filaments are of 40 denier, while the other machine direction layer 13 comprises 20 threads per inch of 0.20mm diameter nylon monofilament yarns 14 twisted two-ply and then five-ply.
• the cross-machine direction yarns 15 are 0.20mm diameter nylon monofilaments twisted two-ply and again two-ply and spaced at 21 threads per inch.
• the woven base fabric 11 is subjected to a needling process in order to attach to its tow-faced side a batt 16
• the embodiments disclosed are endless woven fabrics, wherein the weft yarns of the fabrics, as they exist in the weaving loom, extend in the running or machine direction in the papermaking machine, the invention is also of application to flat woven fabrics. Whilst the invention has been described in the context of a semi-duplex weave, such invention is also of application to other weave structures, whether of single or multi-layer type.
• the base fabric may itself comprise multifilamentary tow in either or both of the warp and weft directions thereof.
• filamentary tow at one face of the base fabric, it is to be understood that, in the event that a batt is to be applied to each surface, such filamentary tow may, if desired, exist at each face of the base fabric.

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• Paper (AREA)
• Filtering Materials (AREA)
• Filters For Electric Vacuum Cleaners (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=26269590

Family Applications (1)

Country Status (7)

Families Citing this family (8)

Family Cites Families (8)

• 1979
  • 1979-11-09 WO PCT/GB1979/000185 patent/WO1980001086A1/en unknown
  • 1979-11-13 IT IT27259/79A patent/IT1195747B/it active
  • 1979-11-14 FI FI793567A patent/FI793567A/fi not_active Application Discontinuation
  • 1979-11-14 NO NO793682A patent/NO793682L/no unknown
  • 1979-11-14 AU AU52817/79A patent/AU5281779A/en not_active Abandoned
  • 1979-11-15 ES ES485987A patent/ES485987A0/es active Granted
• 1980
  • 1980-06-03 EP EP79901462A patent/EP0020556A1/de not_active Withdrawn

Non-Patent Citations (1)

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