Classifications

• • 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
  • D21F7/00—Other details of machines for making continuous webs of paper
  • D21F7/08—Felts
  • D21F7/083—Multi-layer felts

Definitions

• This invention relates to paper machine felts.
• a slurry of paper making constituents referred to as "furnish” is deposited on a fabric or "wire” and the liquid constituents are drawn or extracted therethrough to produce a self-cohesive sheet which is then passed to the pressing and drying sections of the paper-making machine.
• the paper sheet In the pressing section, the paper sheet is transported by a felt to a pair of rollers where the felt and paper sheet pass between the nip of the rollers to dewater and to dry the paper sheet.
• the paper sheet itself may contain all types of chemical finishes and will be, at the same time, subjected to an elevated temperature to aid the dewatering and drying thereof.
• Paper making felts are generally produced by needling batt fibre to a woven backing which then supports the forming paper sheet as it passes through the press. In the nip of the press rolls, the batt fibres are bent and deformed under great pressure and at great frequency and hence the mechanical properties of the batt fibre are of considerable importance in these processes.
• Polyamide 6 and polyamide 6,6 have been used extensively in the manufacture of paper machine felts. These polymers are readily formed as fibres and their fibre characteristics can be controlled to allow production into acceptable felts.
• Many prior art proposals for the use of polyamide materials in sheet and felt materials in general have been proposed.
• British Patent Specification No. 1304732 there is a reference to the use of polyamide such as nylon 6, nylon 6,6, nylon 6.10, nylon 6,7, nylon 8, nylon 9, nylon 11 and nylon 12.
• the specification is concerned with the manufacture of fibrous sheet materials and is not specifically concerned with paper machine clothing.
• British Patent Specification No. 1329132 again relates to a known woven fabric for use, for example, as an interlining.
• polyamide such as nylon 6, nylon 11, nylon 12
• copolyamides such as nylon 6,6 and copolymers of nylon 6 and nylon 6,6 with nylon 11 and nylon 12.
• nylon materials are used primarily for their inherent strength in a clothing or decorative assembly and would not be subjected to the agressive physical and chemical environment of a paper making machine.
• European Patent Specification No. 000708 relates to a paper making machine felt comprising a woven heat set belt which in the machine and transverse direction comprises thermoplastic filaments, in which belt the filaments in at least one of the machine and transverse directions are co-extruded and in which monofilaments have a core of polymer selected from nylon 6,6, polyethylene terephthalate and tetrapolymer of tera or isophthalic acid and a sheet of copolymer selected from nylon 11, nylon 12, nylon 6, nylon 6,10, nylon 6,12, polybutylene terephthalate and a large number of other materials.
• nylon 12 can be used in the construction of a felt for use in a paper making machine.
• nylon 11 has properties which compare favourably with nylon 12 although this would not have been expected from the normal structure thereof.
• Polyamide 11 (polyundecanoamide) referred to in this specification as "PA 11" is well known in polymer technology and as an article of commerce. Polyamide 11 was developed commercially for sources directed primarily to injection moulding applications. The polyamide 11 homopolymer without cross-linking additives may be extruded to form a large number of items and is ideally suited to the formation of monofilaments and fine denier continuous filament yarn.
• batt materials of polyamide 11 when used in paper machine felts have superior durability and enhance recovery from compression and resistance to fibrillation compared with felt materials currently employed.
• polyamide 11 can exhibit a 50-100% greater lifetime use in particularly hostile chemical and abrasive environments in paper making.
• an article of paper machine clothing formed from a fibrous material having a woven base and an optional batt layer attached thereto characterised in that said fibrous material comprises fibres of pol (undecanoamide) (polyamide 11) formed by the extrusion of a melt of polyamide 11 having an intrinsic viscosity of at least 1.0 dl/gram.
• the melt to be extruded may contain 0.2 to 1.0% by weight of an anti-oxidant and more preferably, 0.4 to 0.7% by weight.
• the anti-oxidant may be selected from one or more of alpha-tocopherol, condensation products of diphenylamine and acetone and closely related structures derived from diphenylamine and compatible phenolic stablisers with amide functionality such, for example, as that made commercially available by Ciba Geigy under the trade name "IRGANOX 1098".
• Polyamide fibre containing approximately 0.5 to 0.6% by weight of anti-oxidant individually and separately or in combination results in a further enhancement of durability.
• Poly ⁇ mide 11 resin of the appropriate instrinsic viscosity may be compounded during extrusion of monofilament or continuous filament by the addition of selected anti-oxidants.
• Polyamide 11 monofilament in accordance with the invention may be extruded at temperatures across the barrel between 220°C and 295°C. The spinneret may be maintained at temperatures of approximately 300°C.
• Monofilament may be extruded with the drawdown of between 2.0 X and 4.5X in order to provide onofilaments of 0.1 - 0.25 mm for manufacturing of Fourdrinier or other forming fabrics.
• polyamide 11 monofilament may be also used advantageously as shute filament and/or warp filament in single, double or triple layer of press fabrics.
• polyamide 11 high molecular weight monofilaments may be employed in Fourdrinier forming fabrics as warp or machine direction monofilaments. It is possible in accordance with the invention to prepare high durability all polyamide forming fabrics and avoid a mix of materials presently employed in which polyamide filaments must be alternatively inserted with polyester monofilaments in the shute direction in order to provide a measure of enhanced abrasion resistance without the existence of dimensional instability which normally results from the use of polyamide 6 or polyamide 6,6 material.
• the paper machine felts in accordance with the present invention have a low moisture regain and are relatively insensitive to physical properties in the presence of water.
• Monofilaments may be extruded with variations in the process to deliver this and other desirable tensile properties for the weaving of base materials for needled nonwovens employed in the pressing section of a paper making machine.
• Monofilaments in large diameters may be employed in both the warp and shute directions in dryer screen applications.
• Fine denier monofilaments of high molecular weight polyamide 11 may be extruded with anti-oxidant employing barrel temperatures within the range 215°C to 277°C with a spinneret temperature of approximately 270°C.
• Continuous filament yarn of appropriate denier desirable for various layers of the batt of press felts can thus be extruded and later crimped and cut into staple fibre for batt manufacture and thereafter employed as a batt layer in press felts.
• the advantage of the felts in accordance with the present invention is that such felts have superior durability due to enhanced resistance to fibre fibrillation and recovery from compression which result in compaction resistance.
• superior chemical resistance particularly resistance to hydrolysis and resistance to degradation' of physical properties by hypochlorite and other oxidation.
• Such fibres in press felts exhibit superior durability against abrasion damage experienced with papers containing fillers especially including clay or crushed limestone.
• Such felts exhibit at least
• Figure 1 is a photomicrograph of a compression test of a standard PA 6,6 fibre used in the manufacture of a paper machine felt.
• FIG. 2 is a photomicrograph of a fibre in accordance with the present invention.
• EXAMPLE 1 Continuous filament of PA 11 was prepared according to the following procedure. Commercially available PA 11 was purchased as pellets from Rilsan Corp. , New Jersey, having an intrinsic viscosity of 1.20 dl/g when determined in concentrated sulfuric acid. These polyamide pellets were vacuum dried at 80°C for 16 hours to a final vacuum measured outside the vacuum oven of 140 microns Hg. The pellets were transferred in a manner so as to avoid absorption of moisture from the air to a hopper of a single screw extruder. The extruder was equipped with a 2.5 cm diameter low compression screw. The extruder was fitted with a filter pack of 55 micron nominal porosity.
• the extruder Downstream of the filter the extruder was fitted with a Zenith gear pump metering the melt to a spinneret.
• the spinneret had 30 holes, each hole of diameter 0.5 mm.
• the extruder had a temperature profile ranging from 243°C at the hopper throat to 271°C at the pump with 5 zones of independent temperature monitoring and control.
• the spinneret was maintained at 270°C. Filaments were extruded at approximately 195ft/min with a maximum draw-down such that the radial change was approximately 7-8/1 between spinneret and the first Godet. Yarn was taken up on- a cylinder attached to a Leesona winder after the Godet.
• a typical fibre as-spun according to this procedure was drawn in two stages with a third stage of relaxation all with heat to provide an overall 2.3X draw ratio.
• the first temperature of drawing was at 110°C; relaxation occurred in the 2nd stage at 160°C.
• Fibre from such a process was prepared to be 12.8 dpf (denier per filament). Fibre thus prepared had 4.6 gpd tenacity with an initial modulus of 26 gpd and an elongation at break of 45%.
• the stress-strain curve exhibited a deflection at an elongation of 10% at 3.5 gpd specific stress.
• Such fibre was crimped in a heated stuffer box crimper to provide continuous yarn with a variable random crimp with approximately 4 crimps/cm. It was cut into staple of approximately 7.0 cm length. Such fibre was carded, lapped and needled into a press felt to provide a batt structure at an overall batt weight of approximately 1000 g/m 2 . A felt having such a batt structure exhibited at least 50% increased life in comparison to similar PA 6 felts when challenged with the same furnish on the same position on a paper machine.
• EXAMPLE 2 Fibres were prepared as described in Example 1 with the following exceptions. Prior to drawing, pellets were tumbled with powdered Irganox 1098 (Ciba-Geigy) at a loading such that the blend would be 0.7% wt/wt.
• EXAMPLE 3 Polyamide fibres produced in accordance with Example 1 were formed into a batt structure. Comparable filaments of a standard polyamide 6,6 currently used as an industry standard in the manufacture of paper machine clothing and commercially available under the trade reference T-100 supplied by DuPont was formed into a similar batt. Each of the batts was then incorporated by needling to the backing of a test felt to be run on a compression test machine. The felt containing the two batt samples was installed on the test machine and the machine was run to pass the felt between a pair of nip rollers with a predetermined nip loading. The test felt was run on the compression tester for one million compressions. After the one million compressions, the felt was removed and the batt examined under an electron microscope.
• the candidate fibre PA 11 was, therefore, in substantially better condition after a million compressions than the industry standard. This result was a significant improvement over and above that which would have been expected for polyamide 11 filaments.
• Samples of commercial PA 6,6 fibre of instrinsic viscosity 1.36; commercial PA 6 fibre of instrinsic viscosity 1.46; staple fibre of Examples 1 and 2 above with fibre instrinsic viscosities of 1.05 and 1.12 respectively were each subjected to 35% hydrogen peroxide aqueous solution at pH2 and at 60°C for 24 hours. Retained IV results were as follows:

Landscapes

• Paper (AREA)
• Artificial Filaments (AREA)
• Cleaning Implements For Floors, Carpets, Furniture, Walls, And The Like (AREA)
• Sanitary Thin Papers (AREA)
• Storage Of Web-Like Or Filamentary Materials (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Diaphragms For Electromechanical Transducers (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10647613

Family Applications (1)

Country Status (13)

Families Citing this family (11)

Citations (2)

• 1988
  • 1988-11-28 GB GB888827789A patent/GB8827789D0/en active Pending
• 1989
  • 1989-11-24 WO PCT/GB1989/001410 patent/WO1990006397A1/en active IP Right Grant
  • 1989-11-24 JP JP2500246A patent/JPH04507267A/ja active Pending
  • 1989-11-24 AT AT89312241T patent/ATE96480T1/de not_active IP Right Cessation
  • 1989-11-24 DE DE89312241T patent/DE68910285T2/de not_active Revoked
  • 1989-11-24 BR BR898907793A patent/BR8907793A/pt not_active IP Right Cessation
  • 1989-11-24 AU AU46396/89A patent/AU627251B2/en not_active Ceased
  • 1989-11-24 EP EP89312241A patent/EP0372769B1/en not_active Revoked
  • 1989-11-24 ES ES89312241T patent/ES2045469T3/es not_active Expired - Lifetime
  • 1989-11-27 CA CA002003910A patent/CA2003910A1/en not_active Abandoned
• 1991
  • 1991-05-23 NO NO911984A patent/NO178469C/no not_active IP Right Cessation
  • 1991-05-27 DK DK911008A patent/DK100891D0/da not_active Application Discontinuation
  • 1991-05-28 FI FI912554A patent/FI92943C/fi active

Patent Citations (2)

Also Published As

Similar Documents

Legal Events