Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F3/00—Press section of machines for making continuous webs of paper
  • D21F3/02—Wet presses
  • D21F3/0209—Wet presses with extended press nip
  • D21F3/0218—Shoe presses
  • D21F3/0227—Belts or sleeves therefor
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F1/00—Wet end of machines for making continuous webs of paper
  • D21F1/0027—Screen-cloths
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F1/00—Wet end of machines for making continuous webs of paper
  • D21F1/0027—Screen-cloths
  • D21F1/0036—Multi-layer screen-cloths
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24058—Structurally defined web or sheet [e.g., overall dimension, etc.] including grain, strips, or filamentary elements in respective layers or components in angular relation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24058—Structurally defined web or sheet [e.g., overall dimension, etc.] including grain, strips, or filamentary elements in respective layers or components in angular relation
  • Y10T428/24074—Strand or strand-portions
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24058—Structurally defined web or sheet [e.g., overall dimension, etc.] including grain, strips, or filamentary elements in respective layers or components in angular relation
  • Y10T428/24074—Strand or strand-portions
  • Y10T428/24091—Strand or strand-portions with additional layer[s]

Definitions

• the invention relates to a fabric for use in paper machines as a forming fabric and base fabric for coated, impervious tapes and jackets for wide-nip presses and for forming roll covers.
• fabrics for forming fabrics are made from polymer monofilaments, whereby only polyester monofilaments are used for the longitudinal threads, because only with these the required longitudinal stability can be achieved. Since longitudinal tensions of more than 200 N / cm screen width can certainly occur in the application, for example the essentially wear-resistant or abrasion-resistant polyamide cannot be used as material for the longitudinal threads, because it stretches too much, so that such screens do not would have required required stretch stability.
• base fabrics for coated and liquid-impermeable tapes or jackets for wide-nip presses are made from polyamide threads. Such tapes are guided over a concave shoe and pressed into the shoe by a roller arranged above them. At least one felt web and the paper web to be pressed and thus dewatered run between the shoe and roller.
• press nip press nip
• the degree of dryness of the paper web is significantly improved. Because of the high surface pressure in the press nip, very high demands are placed on the monofilaments of the base fabric of the belt or jacket with regard to their resistance to fibrillation.
• polyamide monofilaments Although these requirements are met by polyamide monofilaments, the above-mentioned poor dimensional stability of polyamide monofilaments often leads to bubbles or circumferential changes, in particular elongations, occurring in the band or in the jacket if the pressure is distributed unevenly across the width. which lead to the fact that the tissue in this area is subject to increased flexing work and is therefore quickly destroyed.
• polyester monofilaments are not sufficiently resistant to fibrillation for such a purpose.
• the surface of the forming rolls of paper machines is designed as a honeycomb-shaped lattice structure. This surface serves as a contact surface, but is much too roughly structured for the fine sieve and would therefore destroy the sieve very quickly at the usual sieving speeds of approx. 1000 m / min and above.
• a hose-like cover made of a stable fabric, preferably in linen weave, with a mesh number of approximately 16 / cm 2 is therefore arranged between the wire and the surface of the forming roller. This so-called forming roll cover is shrunk onto the roll with the help of heat. This requires sufficient shrinkability at temperatures of approx.
• the object of the invention is therefore to design a fabric of the type mentioned at the outset in such a way that the disadvantages explained which occur when using known monofilaments are eliminated and universal applicability is ensured within the scope of the stated application possibilities, which is particularly diverse in economic terms requirements.
• At least part of the longitudinal and / or transverse threads of the fabric consists of a copolymer, the main components of which are a polymer with a high molecular weight, corresponding to a viscosity of at least 0.75, and a copolymer with a high molecular weight , corresponding to a viscosity of at least 0.80, the proportion of the copolymer in the copolymer being 2-20%.
• floating threads In the case of fine forming fabrics, especially those which contain additional fine filler weft, so-called floating threads, the use of mixed polymer monofilaments as floating threads is particularly advantageous since, up to now, the fine floating threads, the diameter of which is usually 0.13 mm and smaller , were very often destroyed when cleaning the sieves.
• the reason for this is the cleaning water directed to the surface of the sieve with high-pressure pointed pipes, which not only damages the sensitive floating threads due to its impact energy.
• the damage caused by fibrillation in the known polyester monofilaments does not occur in the mixed polymer monofilaments or only occurs at greatly increased injection pressures.
• the spray water pressures which were previously around 30 bar, can therefore be increased in favor of more effective screen cleaning.
• the fabric or material according to the invention meets the highest requirements in terms of shape and fibrillation resistance.
• the elongation of a jacket for wide-nip presses made of the material according to the invention in the axial direction is at least 50% less than that of known jackets whose base fabric has the same weave but is woven from polyamide monofilaments. Since the paper machine has to be shut down in order to retighten the jackets in the axial direction, the lower axial expansion means a reduction in the tensioning downtimes, that is to say a better operational use of the machine.
• the fabric according to the invention is far superior to a polyamide fabric as a base fabric.
• Forming roll coverings which are made from the fabric according to the invention, develop shrinkage forces at temperatures of approximately 100 ° to 130 ° C., which are about twice or even higher than with a corresponding polyamide fabric, with sufficient shrinkage. In contrast to the polyamide fabric, this ensures a secure, firm fit of the forming roll covers.
• the fibrillation resistance of the fabric according to the invention not only exceeds that of a polyamide cover, but is even several times higher than that of a polyester cover of the quality previously used.
• the proportion of the copolymer can be between 5% and 10%, polyethylene terephthalate being used as the polymer and dimethyl isophthalate or polybutylene terephthalate being used as the copolymer.
• the viscosity of the polymer can expediently be set to at least 0.85 and that of the copolymer to at least 1.0.
• the fabric according to the invention is used as a paper machine screen, it has proven particularly useful as a single-layer fabric or double-layer fabric, the transverse threads then advantageously consisting of the said mixed polymer.
• the fabric according to the invention is used as a coated, impermeable tape or corresponding jacket for the wide-nip press of a paper machine
• the fabric is used as a base or reinforcing fabric in one layer, at least the longitudinal threads being made of said copolymer.
• the latter also applies in the event that the fabric according to the invention is designed as a double-layer fabric for the application mentioned.
• the fabric according to the invention is used for forming roll coverings, it has proven useful to form the fabric in one layer, both the longitudinal and the transverse threads being made of the said copolymer.

Landscapes

• Paper (AREA)
• Woven Fabrics (AREA)
• Artificial Filaments (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=6358936

Family Applications (1)

Country Status (6)

Families Citing this family (6)

Family Cites Families (5)

• 1988
  • 1988-07-18 DE DE3824324A patent/DE3824324A1/de not_active Withdrawn
• 1989
  • 1989-06-07 EP EP19890110286 patent/EP0351535A3/fr not_active Ceased
  • 1989-06-28 US US07/373,325 patent/US4970100A/en not_active Expired - Fee Related
  • 1989-07-07 JP JP1176978A patent/JPH0268386A/ja active Pending
  • 1989-07-13 FI FI893407A patent/FI893407L/fi not_active Application Discontinuation
  • 1989-07-13 NO NO89892893A patent/NO892893L/no unknown

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