Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
  • D21F11/004—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines by modification of the viscosity of the suspension
• • 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
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/06—Paper forming aids
• • 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
  • D21H13/02—Synthetic cellulose fibres
• • 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
  • D21H15/00—Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution
  • D21H15/02—Pulp or paper, comprising fibres or web-forming material characterised by features other than their chemical constitution characterised by configuration
  • D21H15/06—Long fibres, i.e. fibres exceeding the upper length limit of conventional paper-making fibres; Filaments
• • 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
  • D21H17/57—Polyureas; Polyurethanes

Definitions

• This invention relates to an improved method for the manufacture of a uniform fibrous web comprising textile length fibers by wet forming the web on a conventional paper-making machine.
• this invention relates to a method for forming a uniform web from an unfoamed dispersion of staple length natural or synthetic fibers in water containing a small amount of an associative thickener.
• this invention relates to the use of a nonionic associative thickener consisting essentially of an ethylene oxide based urethane block copolymer having alternating blocks of polyethylene glycol and polyurethane as dispersant and thickener in water as the carrier for natural and synthetic fibers.
• this invention relates to the use of an nonionic associative thickener consisting essentially of a hydroxyethyl cellulose having a long aliphatic side chain as the dispersant and thickener for natural and synthetic cellulosic fibers in a water carrier.
• non-woven fibrous webs containing textile length fibers e.g. synthetic fibers having a length to diameter ratio in the range of from about 300 to about 3000
• a viscous aqueous carrier comprising a dispersant and thickener is required for good dispersion of long thin flexible synthetic fibers, e.g. 1.5 denier by 3i4 inch fibers.
• the long thin synthetic fibers tend to tangle and form flocs or knits in the finished non-woven fabric when formed from an aqueous dispersion suitable for wet-laying paper-making fibers on a paper-making machine.
• Foam furnishes have been proposed as a viscous aqueous carrier medium to ensure good dispersion of the long fibers, for example, as disclosed in U.S. Patent No. 4,049,491. While aqueous foams have been shown to be suitable carriers for staple length fibers, the high viscosity of foam results in relatively slow drainage of water from the wire of the paper-making machine.
• Other methods proposed for this purpose include the addition of thickeners to an unfoamed water carrier, for example, as disclosed in U.S. Patent No. 3,098,786 wherein deacetylated karaya gum and sulfuric acid are included in the water-fiber furnish, and in U.S. Patent No.
• Nonionic associative thickeners have been developed primarily for use in the formulation of latex paints.
• the urethane block copolymers are described by E.J. Schaller and P.J. Rogers-Moses, Resin Review, Vol. XXXVl, No. 2, pp 19-26, incorporated herein by reference.
• the hydrophobically- modified hydroxyethylcellulose nonionic associative thickeners are described by K.G. Shaw and D.P. Liepold, Journal of Coatings Technology 57, No.
• associative thickeners are used to give the formulation certain desirable properties, e.g., enough viscosity to resist running and over-spreading; spatter resistance; and improved leveling properties.
• these nonionic associative thickeners have been used in the manufacture of a water laid fabric web.
• a dispersion of fibers in water is made up with a small amount of an associative thickener which acts as both a surfactant (or dispersant) and as a thickener, slightly increasing the viscosity of the water carrier medium and acting as a lubricant for the fibers.
• an associative thickener which acts as both a surfactant (or dispersant) and as a thickener, slightly increasing the viscosity of the water carrier medium and acting as a lubricant for the fibers.
• One class of nonionic associative thickeners preferred in the process of this invention comprises relatively low (50,000 to 500,000) molecular weight ethylene oxide based urethane block copolymers and is disclosed in U.S. Patents Nos. 4,079,028 and 4,155,892, incorporated herein by reference. These associative thickeners are particularly effective when the fiber furnish contains 10 percent or more staple length hydrophobic fibers.
• Acrysol RM-825 is a 25 percent solids grade of polymer in a mixture of 25 percent butyl carbitol (a diethylene glycol monobutyl ether) and 75 percent water.
• Acrysol Rheology Modifier QR-708 a 35 percent solids grade in a mixture of 60 percent propylene glycol and 40 percent water, has been found to produce excellent results in test runs as reported in Examples 1 and 2. below.
• Another class of associative thickeners preferred for making up fiber furnishes containing predominantly cellulosic fibers, e.g., rayon fibers or a blend of wood fibers and synthetic cellulosic fibers, such as rayon, comprises modified nonionic cellulose ethers of the type disclosed in U.S. Patent No. 4,228,277, incorporated herein by reference, and sold under the trade name Aqualon by Hercules Incorporated, Wilmington, Delaware.
• Aqualon WSP M-1017 a hydroxyethyl cellulose modified with a C- c to C2'- side chain alkyl group and having a molecular weight in the range of 50,000 to 400,000 was found to be particularly effective for the preparation of fiber furnishes comprising rayon fibers, as illustrated in Example 3.
• the urethane block copolymers described hereinabove are effective as a nonionic thickener and dispersant for the preparation of fiber furnishes containing textile length hydrophobic fibers, for example, polyester, acrylic, polyamide, polyolefin, and modified acrylic fibers in a water carrier.
• the nonionic urethane block copolymers are of especial importance in the preparation of unfoamed fiber in water furnishes containing textile length hydrophobic fibers alone or in admixture with cellulosic paper- making fibers.
• the modified nonionic cellulose ethers described hereinabove are particularly useful in the preparation of fiber furnishes in which the textile length fibers are cellulosic fibers. e.g. rayon fibers.
• the hydrophobic fibers forming the aqueous dispersion and the ultimate fabric may comprise from about 10 to about 100 percent by weight of staple length fibers and from 0 to 90 percent conventional wood fibers. Synthetic fibers in the size range of 1 to 4 denier by 3/4 to 1.5 inch are preferred.
• Suitable textile fibers include polyester fibers, e.g. those sold under the trade names Trevira, Dacron. Kodel, Fortrel, etc.; acrylic fibers, e.g. those sold under the trade names Creslan. Acrilan, Orlon, etc.: polyamide fibers, e.g. nylons: polyolefin fibers, e.g. polypropylene; and modified acrylic fibers including those sold under the trade name Dynel.
• Inorganic fibers including glass fibers may comprise part or all of the textile length fibers. Any of the wood cellulose fibers may be used with either type nonionic associative thickener; those comprising or consisting essentially of soft wood fibers are preferred. Other fibers may be used in conjunction with or instead of wood cellulose fibers. In addition to rayon, other known cellulosic fibers, e.g. cotton linters, may be used in the process. The modified nonionic hydroxyethyl cellulose associative thickeners are, however, relatively ineffective for dispersion of hydrophobic fibers.
• the wood cellulose pulp is dispersed in water prior to adding the associative thickener. followed by the addition of the associative thickener and then the addition and dispersion of the staple length fibers. Finally, the dispersion of mixed fibers in an unfoamed water carrier is diluted to the desired headbox consistency and dispensed onto the forming wire of a conventional papermaking machine.
• An antifoam agent may be added to the dispersion to prevent foaming, if necessary, and a wetting agent may be employed to assist in wetting the staple length fibers if desired.
• the fibers preferably are made up into an aqueous dispersion suitable for wet forming on a moving wire former in the following manner.
• the wood pulp is first dispersed in water or in recycled white water to a consistency of about 1 to 2 percent.
• a nonionic associative thickener is added to the resulting slurry in an amount within the range of about 100 to 500 ppm followed by the addition of the textile length fibers with continuous mixing under low shear conditions.
• a non-woven fabric web may be formed from a staple length textile fiber furnish on high speed conventional Fourdrinier papermaking machines to produce a strong, uniform product of excellent formation.
• a small amount of a conventional polymer thickener may be added to the dispersion to more precisely control drainage of which water from the wire during web formation. While a number of nonionic polymers may be used for this purpose, the anionic polymer sold under the trade name Hydraid 7300-C by Calgon Inc., Pittsburgh, Pennsylvania is particularly effective at concentrations of the order of 100 ppm.
• a defoamer e.g. the product sold under the trade name DF-122 by Diamond Shamrock Company may be added, if required, during the preparation of the fiber furnish to eliminate foam formation in the dispersion.
• a number of advantages result from dispersion of staple length fibers in a water solution of a nonionic associative thickener as compared with dispersions in foam or water containing surfactants and conventional polymer thickeners.
• the lower nascent viscosity of the aqueous carrier composition of this invention results in higher drainage rates through the forming wire and permits formation on conventional Fourdrinier machines at high wire speeds.
• special machines with sloping wires and conforming headboxes are not required for operation of our process.
• the dispersion is neither excessively thickened nor foamed, making it possible to handle the dispersion with conventional centrifugal pumps and to use conventional headboxes and forming wires, and to operate such equipment at high wire speeds. Good dispersion of the fibers is obtained without the need for high energy pulping equipment. Additionally. the total chemical usage is lower in the process of this invention than for processes currently used for forming non-woven fabric webs from staple length fibers.
• a batch fiber-water dispersion was made up with 6000 pounds of water in a mix tank equipped with a nonstapling agitator by adding in the following order: a) 46 pounds of West Coast bleached softwood slush pulp at 36% solids; b) 1.6 pounds of nonionic associative thickner, Acrysol QR-708, 34% active (Rohm and Haas Philadelphia, PA); and c) 16.5 pounds of polyester staple, 1.5 denier ⁇ 3/4-inch (Hoechst Trevira Type 101 SD OW). The mixture was agitated for 20 minutes and then pumped with a centrifugal pump to the exit side of a fan pump where it was diluted to 0.08% consistency with white water at 100°F.
• a trial run was made with a furnish of 60 weight percent of Marathon Northern Softwood blended kraft pulp and 40 weight percent 1.5 denier ⁇ 3/4-inch polyester fibers.
• a 4000 gallon capacity hi-lo pulper was used to break up dried sheets of the bleached kraft pulp.
• Three thousand gallons of fresh water heated to 88°F. was added first, then 300 pounds of the pulp was added.
• the pulp was dispersed by using both high and low agitators for 25 minutes. Then 20 pounds of Acrysol QR-708 (34% active) was dissolved in five gallons of water at 160°F.
• the dispersion from the machine chest was pumped to the headbox of a wire former with a centnfugal pump where it was diluted to 0.065% consistency with white water which contained 100 ppm Acrysol QR-708 and 100 ppm Hydraid 7300-C.
• Table I lists the viscosity data obtained during the trial using the UL attachment to a Brookfield viscometer and Table II, below, lists the physical properties of the product web. (1) The headbox viscosity was lower than the machine chest viscosity because of dilution of the stock to the headbox with plain water.
• Ib/rm handsheets consisting of 70% 1.5 denier 1 1 2 inch rayon fibers and 30% Ontario soft wood kraft pulp were made on an M/K Systems. Inc. Series 8000 Computerized Sheet Former consisting of three main components: the Sheet Former itself with its Forming and Pressing, Drying sections. a 200-liter stock tank. and a Hewlett Packard HP-85 desk top computer which controls the operation of the Sheet Former.
• the press pressure was set at 20 psi and the felt tension was set at 20 psi.

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• 1988
  • 1988-03-30 DE DE19883853848 patent/DE3853848T2/de not_active Expired - Fee Related
  • 1988-03-30 EP EP19880302889 patent/EP0286318B1/fr not_active Expired - Lifetime
  • 1988-04-05 FI FI881557A patent/FI881557A/fi not_active Application Discontinuation
  • 1988-04-05 JP JP63082386A patent/JPS63282349A/ja active Pending

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