Classifications

• • D—TEXTILES; PAPER
  • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
  • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
  • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
  • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
  • D06M15/37—Macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D06M15/39—Aldehyde resins; Ketone resins; Polyacetals
  • D06M15/41—Phenol-aldehyde or phenol-ketone resins
• • D—TEXTILES; PAPER
  • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
  • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
  • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
  • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
  • D01F6/60—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides

Definitions

• This invention relates to paper machine pressing fabrics and has particular reference to paper machine pressing fabrics formed of a polyamide material and having improved longevity and resistance to flattening in the surface layer.
• a slurry of paper making constituents referred to as "furnish” is deposited on a forming fabric or "wire” and the liquid constituent furnish is drawn or extracted through the fabric or wire to produce a self-cohesive sheet.
• This self-cohesive sheet is then passed to a pressing and then a drying section of the paper making machine.
• the paper sheet is transported by a pressing fabric to a pair of rollers where the fabric and the paper sheet pass between the nip of the rollers to dewater by mechanical pressure the paper sheet.
• the paper sheet itself may contain other types of chemical finishes and additives and could be, at the same time, subjected to an elevated temperature in order to aid the dewatering.
• the paper making pressing fabric together with its sheet of paper tends, therefore, to be subjected to immense pressure at elevated temperatures in a rigorous chemical environment.
• Paper making pressing fabrics are generally produced by needling batt fiber to a woven base fabric. The fabric has multiple functions: first, to support the formed paper sheet through the press section of the machine; secondly, to accept sheet water expressed at each press nip; and last, to impart a finish or surface texture to the paper sheet.
• the batt fiber layer constitutes a "cushion" and support for the paper sheet while the woven base provides the primary channels or voids to accept expressed sheet water.
• the quality of the batt fiber layer and in particular its surface properties and its consistency of surface properties with time, is of extreme importance. As the surface properties of the batt fiber layer deteriorates, so does the quality of the surface of the paper sheet being pressed, as well as, the uniformity of water removal.
• the batt fibers are bent and deformed under great pressure and at great frequency. Hence the mechanical properties of the batt fiber are of considerable importance in such processes.
• Polyamide 6 and polyamide 6,6 have been used extensively in the manufacture of paper machine pressing fabrics. These polymers are readily formable as fibers and their fiber characteristics can be controlled to make acceptable paper making pressing fabrics.
• PA polyamide
• United States Patent Specification No. 2,434,247 relates to the modification of synthetic linear polyamides with formaldehyde and an alcohol to obtain a more elastic nylon for woven fabrics.
• United States Patent Specification No. 2,430,953 is concerned with producing nylon yarns with a softer hand, better drape, and in addition, a higher melting point, better dye receptivity and increased resistnce to solvents.
• the polyamide yarns are reacted with formaldehyde at a pH below 3 in alcohol.
• United States Patent Specification No. 2,425,334 relates to modification of polyamides with formaldehyde at a pH less than 3 so that they can be cold drawn by no more than 75% of their original lengths.
• United States Patent Specification No. 3,276,839 describes a process for finishing and dyeing synthetic nylon textile materials in the presence of phenol and an aliphatic anion-active compound in alkaline medium.
• United States Patent Specification No. 3,322,488 refers to sulfomethylated bisphenol-formaldehyde condensation products used as dye resists for synthetic polyamide fibers.
• United States Patent Specification No. 2,533,100 relates to a process for treating synthetic linear polyamides with thio derivatives of phenols or their corresponding reduction products.
• United States Patent Specification No. 2,388,676 is concerned with improving the light stability of polyamide fibers by forming a catecholaldehyde resin within the nylon.
• nylon materials exhibit improved properties for use in apparrel or decorative assembly, i.e. use in conditions that will not be subjected to the agressive physical and chemical environment of a paper making machine.
• the present applicant has discovered that a paper making pressing fabric using fibers of various polyamides having an increased amine end group concentration can be further processed and modified to produce significantly improved properties.
• a paper making pressing fabric comprising a fiber layer formed of various polyamides characterised in that said polyamide has an amine end group concentration such that the amine end group/carboxy end group ratio is greater than 1 which has been subjected to a phenol/aldehyde treatment process to increase the intrinsic viscosity of by at least 4% compared with the untreated material.
• the amine end group concentration is at least 60 equivalents/106g.
• the polyamide is polyamide 6,6
• the intrinsic viscosity after treatment process is preferably not less than 1.3 dl/g; said fiber layer can just be the surface layer or layers of the batt structure and/or any portion of the batt up to 100% of the batt structure.
• a method of making a paper making pressing fabric which method comprises treating a polyamide fiber having an amine end group concentration of at least 60 equivalent/106 gram with an aldehyde/phenol treatment process by contacting the fiber with an aqueous solution of an aldehyde at an elevated temperature and with an aqueous solution of a phenol at an elevated temperature, the treatment process being carried out at a temperature for a time sufficient to impart an increase in intrinsic viscosity of the polyamide by at least 4% and thereafter forming a layer of said fibers and needling onto a woven base fabric.
• the fiber may be formed into a batt layer prior to attaching to the base fabric either before or after the aldehyde/phenol treatment procedure.
• the woven base fabrics contain yarns of monofilament, multifilament, or spun from staple fibers, that are usually polyamide based
• the technology of the present invention can be utilized for these yarn forms since they are also exposed to the heat, pressure and chemical environment already described. Benefits of dimensional stability, strength retention and maintenance of water handling capacity are all vital, and will be improved using yarns prepared by this invention.
• fiber should also not be limited in the sense of size dimensions or shape, but be considered a component. In this sense, therefore, for the purposes of this specification, the use of the term “fiber” should also include “yarns”.
• Phenols which can be used in this process include phenol, pyrocatechol, resorcinol, hydroquinone, pyrogallol and phloroglucinol, as well as, substituted products of the aforementioned compounds provided at least two reactive sites are left open on the aromatic ring.
• bisphenols, dihydroxy-naphthalenes and the like could also be utilized.
• Aldehydes applicable to this process are formaldehyde, formaldehyde liberating compounds, oxaldehyde, malonaldehyde, succinaldehyde, glutaraldehyde, adipaldehyde, pimelaldehyde, suberaldehyde, azelaldehyde and sebacaldehyde, and the like, as well as their substituted counterparts.
• the treated polyamide batt fibers show an increase in intrinsic viscosity up to 25% depending on the phenolic compound and subsequent heat treatment employed. These fibers also exhibit higher wet elongations relative to standard polyamide fibers both before, but especially after the treatment process. There is also a significant improvement in chemical resistance particularly in terms of resistance to degradation of physical properties caused by oxidation by chlorine containing compounds during use on a paper making machine. Fibers also show increased resistance to abrasion resulting from the pressing of papers containing fillers, such as ground calcium carbonate. Such pressing fabrics have exhibited as much as 100% longer lifetime in use, particularly in hostile chemical and mechanically abrasive environments.
• Polyamide 6,6 15d staple fiber having an amine end group concentration of 66.4 equivalent/106 gram and an intrinsic viscosity of 1.35 dl/g was subjected to a phenolic treatment process as described below.
• the fiber was first immersed in an aqueous bath consisting of 0.5% ethylene diamine and 2.0% formaldehyde at 130°F for 30 minutes. After a rinse, the fiber is then subjected to a second aqueous solution of 1.5% resorcinol and 1% formaldehyde at 130°F for one hour. Followinged by a rinse cycle, the sample was subsequently air dried and heated 10 minutes at 300°F.
• Table 1 compares intrinsic viscosities and tensile properties of fiber processed with the above formulation and untreated PA 6,6 fibers having high and low amine end groups.
• Table 2 includes data describing the properties after exposure to sodium hypochlorite solution in a standard degradation test.
• Table 3 shows that the treated high amine end group fibers give superior properties in terms of improved ranking on the simulated papermaking press. According to the table, the lower the ranking the better the results.
• the trial fabric structure utilized was composed of 100% of the modified polyamide fiber, with the addition of the special process steps of the invention.
• Our trial ran 12 days and was scheduled off.
• the fabric showed no signs of instability and our analysis of the used fabric revealed low weight loss, no fiber fibrillation and fatigue, and little loss to bulk and water handling capacity.

Landscapes

• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• General Chemical & Material Sciences (AREA)
• Paper (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
• Polarising Elements (AREA)
• Artificial Filaments (AREA)
• Polyamides (AREA)
• Reinforced Plastic Materials (AREA)
• Heat Sensitive Colour Forming Recording (AREA)
• Woven Fabrics (AREA)
• Filtering Materials (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Solid-Sorbent Or Filter-Aiding Compositions (AREA)
• Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
• Nonwoven Fabrics (AREA)
• Treatment Of Fiber Materials (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Printing Plates And Materials Therefor (AREA)
• Diaphragms For Electromechanical Transducers (AREA)

Applications Claiming Priority (2)

Publications (3)

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Family Applications (1)

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Cited By (1)

Citations (6)

• 1990
  • 1990-03-20 NO NO901281A patent/NO179711C/no unknown
  • 1990-03-21 EP EP90303023A patent/EP0392682B1/de not_active Expired - Lifetime
  • 1990-03-21 ES ES90303023T patent/ES2078304T3/es not_active Expired - Lifetime
  • 1990-03-21 DE DE69021612T patent/DE69021612T2/de not_active Expired - Fee Related
  • 1990-03-21 AT AT90303023T patent/ATE126526T1/de not_active IP Right Cessation
  • 1990-03-21 DK DK90303023.7T patent/DK0392682T3/da active
  • 1990-03-22 ZA ZA902210A patent/ZA902210B/xx unknown
  • 1990-03-23 FI FI901474A patent/FI101154B/fi not_active IP Right Cessation
  • 1990-04-04 CA CA002013852A patent/CA2013852C/en not_active Expired - Fee Related
  • 1990-04-12 AU AU53266/90A patent/AU626659B2/en not_active Ceased
  • 1990-04-12 JP JP2095205A patent/JPH072839B2/ja not_active Expired - Lifetime
  • 1990-04-13 KR KR1019900005131A patent/KR950013485B1/ko not_active IP Right Cessation
• 1995
  • 1995-09-21 GR GR950402605T patent/GR3017488T3/el unknown

Patent Citations (7)

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