Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
  • D21H13/10—Organic non-cellulose fibres
  • D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H13/26—Polyamides; Polyimides
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/54—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen
  • D21H17/55—Polyamides; Polyaminoamides; Polyester-amides
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H5/00—Special paper or cardboard not otherwise provided for
  • D21H5/12—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials
  • D21H5/1272—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of fibres which can be physically or chemically modified during or after web formation
  • D21H5/129—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of fibres which can be physically or chemically modified during or after web formation by thermal treatment

Definitions

• the invention relates to novel non-woven fibrous structures made from synthetic fibers and bonded at the crossing points of the fibers, and to a method of producing such structures.
• a binder is generally applied to the fibers or to an already formed sheet or mat, whereby the fibers are bonded at their crossing points. Subsequently, the binder is cured or hardened by a heat treatment of the mat.
• the thus obtained web has the drawback that each fiber is coated with a thin cured film of the binder and that, therefore, not the original fiber but the binder l film largely determines the properties of the Web.
• a dry process has been developed where a conventional staple fiber is treatedwith a hydrophobic or water repellent agent and the dry felt of such fibers is sprayed with an aqueous solution or' dispersion of a binder.
• the droplets or globules of such solution or dispersion do not spread on the hydrophobic fiber surface but fiow thereon to the crossing points of superposed fibers and remain there suspended.
• the water is evaporated and the binder cured.
• the synthetic fibers employed include polyamides such as nylon 66 (hexamethylene diamine-adipic acid condensation product), nylon 6 (polycaprolactam) and other nylon products (nylon 6/10; nylon 11); polyesters from dicarboxylic acids, such as terephthalic or isophthalic acid and diols or polyols (Dacron, Diolen, Terylene); vinyl polymers and copolymers on vinyl chloride or vinyl acetate basis (Vinyon); vinylidene chloride polymers and copolymers (Saran); polyacrylics (Dralon; Orion; Acrylan; Creslan; Acrylast) and copolymers, e.g.
• polyamides such as nylon 66 (hexamethylene diamine-adipic acid condensation product), nylon 6 (polycaprolactam) and other nylon products (nylon 6/10; nylon 11
• polyesters from dicarboxylic acids such as terephthalic or isophthalic acid and diols or poly
• acrylonitrile with styrene polyolefines such as polyethylene or polypropylene; polytetrafiuoroethylene (Teflon); modified and regenerated cellulose fibers such as viscose, cuproammonium, cellulose acetate; also glass fibers and other synthetic fibers may be used, as well as mixtures of different fibers. Up to 50 percent of the synthetic fibers may be replaced by natural fibers.
• lubricants compounds used to produce on the fiber a coating film presenting a gliding surface for the binder droplets which collect finally at the crossing points of the fibers and form there a bond, without covering the remaining part of the fibers in the finished article.
• the lubricants must be insoluble in water; they may be liquid at room temperature and must have a melting point below 120 C., preferably not higher than 80 C. In the liquid state, they must be immiscible with the liquid binder. Suitable lubricants are rosin and rosin soaps, or waxes such as parafiin wax.
• Preferred lubricants are compounds conventionally used as plasticizers for resins, particularly phthalates such as dimethylglycol phthalate, benzylbutyl phthalate, dibutyl phthalate, phthalic esters of C -C alcohols such as dioctyl phthalate, and others. Also esters of aliphatic or aromatic dicarboxylic acids with aliphatic and/or aromatic monohydric or dihydric alcohols, such as benzyl octyl adipate, may be used.
• Suitable plasticizer-lubricants available in commerce are, for instance, sold under the trade-names Scadoplast RA 3L (polyester of adipic acid) and Scadoplast RS 20 (polyester of sebacic acid); polyesters of phthalic acid are marketed under the trade-names Scadoplast W L and plasticizer CEL (Farbenfabriken Bayer AG.)
• the lubricant and binder may be added to the fibers either separately or together. This can be done in various ways.'For instance, the fibers may be first contacted with the liquid or liquefied lubricant so as to receive a thin coating of the same; subsequently, the binder is applied in a similar manner so as to produce a thin film ion the lubricant coating. Another possibility consists in mixing the lubricant and binder to a homogeneous mixture which is added in form of a powder or of fibers to the slurry of the fibers to be bonded in the box of a paper machine. In another modification of the process, the binder is converted to a filament and coated with the lubricant, whereupon the coated binder filament is comminuted to staple fiber and added to the aqueous slurry of the fibers forming the mat.
• the use of the binder in a filamentary foam has the J) advantage to prevent or reduce the risk that binder is carried away by the white water during formation of the sheet. Therefore, it is not necessary to use an excess of the binder.
• the lubricant is molten in the drying part of the machine and covers the fibers with a thin film.
• the binder added in powdery or filamentary form melts also and flows on the coated fiber surface to the crossing points of the fibers.
• the droplets or globules formed at said crossing points form a kind of knot.
• the even distribution of the binder in the mat ensures a bonding of the crossing points not only at the surface of the sheet but also in the inside layers thereof.
• the binder used was a polyurethane forming mixture of polyesters and polyisocyanates whose isocyanate groups were blocked by an alcohol or phenol and became reactive only at a temperature of about 100 C.
• Said latent adhesive agent when exerting its bonding properties on heating, had then to be cured by further heating.
• the resins are applied in the same manner as set forth above for the binder. For instance, they may be spun to filaments which are then cut to staple fibers of the desired length and admixed in the machine chest to the fibrous slurry from which the web is formed.
• the synthetic fibers may be mixed previously with the lubricant, or the binder filaments may be coated with the lubricant. While the batt passes through a heating zone, the lubricant melts and coats the synthetic fibers. When the temperature is further raised, also the thermoplastic binder fiber melts and contracts to separate droplets. As the synthetic fiber and the droplets of the binder material is separated by the film of the lubricant, said droplet glides to the next crossing point. When the Web is cooled, the droplets solidify and bond the fibers together at their intersections.
• the polyamide resin must be resistant to oxygen at 3500 centipoises, which viscosity corresponds to a flow-out time of about 50 to 80 seconds at 110 C. in the DIN- cup of the German testing standards having a 4 mm. nozzle.
• thermoplastic binder also in powdery form homogenized with the lubricant.
• the lubricant-binder mixtures or filaments may contain the lubricant in amounts of 2 to 5 percent by weight, the balance being polyamide resin. About 25 to 50 percent, calculated on dry fiber weight, are added to the fibrous slurry.
• Nylon staple fibers of 6 mm. length and 1.5 den. were beaten in water and passed into the machine chest. Subsequently, staple fibers cut from binder-lubricant filaments were introduced into the chest in an amount of 30 percent by weight, calculated on dry weight basis of the nylon fibers.
• the binder-lubricant fiber had been prepared by mixing percent by weight of a polyaminoamide resin A with 15 percent of a polyaminoamide resin B.
• Resin A had been obtained by a reaction as described in Example 3 of Patent No. 2,728,737 and had a viscosity of 30-45 poise at 150 C. and a molecular weight of about 7400.
• Resin B had been obtained by a reaction as described in Example 1 of Patent No. 2,767,089 and had a viscosity of 10-15 poises at 150 C. The mixture was heated at 150 C. and the molten resin was spun through a spinneret to a filament.
• the solidified filament was passed through a bath of dimethylglycol phthalate and then between squeeze rolls to strip the excess of the dimethylglycol phthalate.
• the filament thus provided with a thin film of the lubricant was finally wound upon a reel and later cut to staple fibers of the desired length which were added to the fibrous slurry in the chest.
• the fibrous mixture in the chest is then formed into a web on a conventional papermaking machine.
• the web is heated in the dryer section of the machine for a short time at a temperature of about 150 C.; thereby, the melting point of the thermoplastic polyamide adhesive is exceeded and the adhesive melts, which produces a separation of the lubricant and adhesive.
• the lubricant forms a thin coating on the nylon fibers while the polyamide resin breaks up to droplets which migrate on the lubricant film to the points of intersection of the fibers. Following the heat shock, the web is cooled, whereby the resin droplets solidify at said points of intersection and form a firm bond. Subsequently, the lubricant is washed off, and the web is wound up.
• a method of preparing an unwoven web material from at least 50 percent of synthetic fibers comprising adding to an aqueous slurry of said fibers passing through a papermaking machine a water insoluble lubricant material selected from the group consisting of natural and synthetic resins, waxes, and plasticizers, said material forming in the liquid state a removable film on said fibers, and fibers of a thermoplastic polyamide composition, said lubricant material having a melting point not higher than C.
• said polyamide composition having a melting point higher than said lubricant material, said polyamide composition having the polyaeyl group of polymeric fat acids, and the polyamino group of an aliphatic polyamine, subjecting said fibers to a temperature sufficient to melt said polyamide composition, said molten polyamide composition collecting on the film of the lubricant material formed on the fibers as droplets at the intercrossing points of the fibers and solidifying thereon cooling to form bonds at said intercrossing points.
• An unwoven fibrous product consisting essentially of intercrossing non-fibrillating synthetic fibers, the fibers being bonded at their intercrossing points by a thermoplastic polyamide resin, the polyamide having the polyacyl group of polymeric fat acids and the polyamino group of an aliphatic polyamine, the fibers being otherwise substantially free of polyamide coating.
• lubricant and binder are added in a total amount of at least percent, based on the dry weight of the fibers, the lubricant comprising about 2 to 5 percent of said total amount.
• said polyamide fibers consist of a mixture of a high melting polyamide having at 150 C. a viscosity of -45 poises and a low melting polyamide having at 150 C. a viscosity of 10-15 poises, said mixture having a susbtantially uniform melting point of to C. and a. viscosity of 25 to 35 poises.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=6976230

Family Applications (1)

Country Status (8)

Cited By (9)

Citations (4)

• 0
  • NL NL134976D patent/NL134976C/xx active
  • BE BE638830D patent/BE638830A/xx unknown
  • NL NL299389D patent/NL299389A/xx unknown
• 1963
  • 1963-08-19 LU LU44289D patent/LU44289A1/xx unknown
  • 1963-08-23 GB GB33501/63A patent/GB1037267A/en not_active Expired
  • 1963-09-18 CH CH1151263A patent/CH416307A/de unknown
  • 1963-09-26 DK DK453263AA patent/DK113618B/da unknown
  • 1963-10-11 US US315681A patent/US3401078A/en not_active Expired - Lifetime
  • 1963-10-17 AT AT831163A patent/AT251403B/de active

Patent Citations (4)

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