US3902957A - Process of making fibers - Google Patents

Process of making fibers Download PDF

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US3902957A
US3902957A US348352A US34835273A US3902957A US 3902957 A US3902957 A US 3902957A US 348352 A US348352 A US 348352A US 34835273 A US34835273 A US 34835273A US 3902957 A US3902957 A US 3902957A
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fibrous product
temperature
solvent
polymer
refining
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John H Kozlowski
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Fort James Corp
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Crown Zellerbach Corp
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Priority to JP3803274A priority patent/JPS5717963B2/ja
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    • 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
    • D21H5/20—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres
    • D21H5/202—Special paper or cardboard not otherwise provided for characterised by the use of special fibrous materials of organic non-cellulosic fibres too short for spinning, with or without cellulose fibres polyolefins
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/11—Flash-spinning
    • 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
    • D21H13/12—Organic non-cellulose fibres from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D21H13/14—Polyalkenes, e.g. polystyrene polyethylene

Definitions

  • ABSTRACT An improved process of manufacturing fibers by the technique of forming a mixture of polymer, solvent for such polymer and, optionally, water or other flashing aids, at a temperature (flash temperature) which is high enough to bring the polymer to a plastic state and which will permit substantially complete vaporization of the solvent when the mixture is flashed, flashing the mixture into a flash zone to produce a fibrous product, and subsequently refining the fibrous product characterized in that the fibrous product is first passed through a primary refining zone at a temperature above the boiling point of the solvent, and then subjecting the fibrous product to a secondary refining.
  • flash temperature a temperature which is high enough to bring the polymer to a plastic state and which will permit substantially complete vaporization of the solvent when the mixture is flashed
  • the primary refining is effected under conditions such that only a light defibering action is imparted to the fibrous product, and is preferably carried out in a disc refiner having wide plate clearances.
  • the secondary refining is carried out under conditions to impart a vigorous fiberillating action to the fibrous product and provide a pulp having a drainage factor in excess of 1.0 second/gram.
  • OLS No. 2,147,461 describes a process in which molten polymer is emulsified with water (optionally, with a minor amount of solvent in the polymer phase) and then heated and flashed to a reduced pressure zone to form fibers.
  • Fibrous materials produced under the general process conditions described in these references tend to be interconnected or bundled together toan undesirable degree and the paper produced therefrom isundesirably low in strength (e.g., tensile strength). Such fibrous material is more difficult to separate, cut or refine in preparation for papermaking and contains a high content of gels and chunks of polymer which cause undesirable fish eyes or transparent spots in paper manufactured therefrom.
  • that process comprises flashing into a zone at subatmospheric pressure to provide a fibrous product having a temperature less than C. and subsequently refining the pulp at this low temperature, preferably while maintaining the pulp under such subatmospheric conditions in order to minimize condensation of solvent vapor. While this approach is satisfactory from a technical point of view, it is expensive to practice commercially because of the vacuum requirements imposed on the system. Also, the amount of unvaporized solvent remaining in the fibrous product after refining is such as to require further solvent elimination measures.
  • the purpose of the present invention is to provide an economical technique applicable to all of the flashing processes previously described which will produce a pulp useful for producing synthetic paper by conventional papermaking techniques which has surprisingly improved properties and a low content of solvent, gels and chunks.
  • the present process comprises taking the flashed fibrous product produced by the foregoing processes, forming an aqueous mixture of the fibrous product while maintaining the product at a temperature above the boiling point of the solvent(s) employed in the solution or dispersion, passing the fibrous product at such a temperature through a primary refining zone operated under conditions such that the fibrous product is subjected only to a light shredding or defibering action, and passing the fibrous product through a sec ondary refining zone under conditions such that the fibrous product is given vigorous fibrillating action.
  • the fibrous product is cooled prior to secondary refining.
  • any polymer or copolymer may be employed which is capable of forming fibers by conventional spinning techniques. It is preferred to employ crystalline or partially crystalline polyolefins such aslow pressure polyethylene, isotactic or partially isotactic polypropylene, and ethylene-propylene copolymers. Additionally, polybutenes and polymethyl pentenes may be employed in the practice of this invention. Crystalline or partially crystalline polyamides and polyesters may also be used. Noncrystalline polymers such as polycarbonates, polysulfones, polyvinyl chloride, polymethylmethacrylate, polyacrylonitrile and polystyrene may be used. Mixtures of the foregoing with each other or other polymers may also be employed.
  • the preferred polyolefins employed are those having an intrinsic viscosity above about 0.7 dl/g., which for high density polyethylene corresponds to a viscosity average molecular weight of about 30,000 to 40,000.
  • the polymers employed in practicing the present process may be in the form of dried powder or pellets or, preferably, as a wet cake, slurry or solution of polyolefin in the reaction solvent as obtained after polymerization.
  • any substituted or unsubstituted aliphatic, aromatic or cyclic hydrocarbon which is a solvent for the polymer at elevated temperatures and pressures, which is relatively inert under the conditions of operation and which has a boiling point at atmospheric pressure that is between 20 C. and 100 C., preferably between 50 C. and 100 C., and at the flash zone temperature less than the softening p3 int of the polymer may be employed in practicing the present process.
  • the preferred solvent is hexane which has a boiling point of 68.7 C. at atmospheric pressure.
  • the polymer-solvent mixture may be formed by any one of several methods.
  • One may start with a solution of polymer in solvent as it comes from a solution polymerization process, either at the same concentration, diluted or concentrated.
  • a slurry of polymer particles in the solvent such as is produced by a slurry of polymerization procedure and the appropriate amount of water is added to the slurry or vice versa.
  • a further alternative would be to start with a dry polymer powder, or granules, or a wet cake such as might be produced at some stage of solvent removal in the polymer plant and the appropriate amount of solvent is admixed therewith.
  • the polymer concentration relative to the solvent is not critical, the solvent being present in an amount that is greater than 100% by weight of the polymer and sufficient to give a viscosity at the flash temperature employed that can be easily handled. Frequently, this viscosity will be up to about 3,500 centipoises. Generally, the polymer concentration will vary from about 2% to about 30% by weight of the solvent plus polymer, and preferably is in the range of about 5% to about
  • water is employed as a flashing aid. In this embodiment the water may be in a continuous phase or discontinuous phase, depending upon the amount of water added to the polymersolvent mixture and the manner of addition. If the water is to form the discontinuous phase it should be present in an amount less than 70%.
  • the water should be present in an amount greater than 30% by volume of the mixture and preferably between 50% and 70%.
  • the particular method of mixing is not critical, but if it is desired to have the water form a discontinuous phase it has been found to be advantageous to have the solvent present prior to water addition since the solvent or polymer solution will form the continuous phase of the mixture to be formed. This latter approach is particularly desirable when one employs an amount of water which is near the borderline of an inversion occurring, i.e., at the point where the amount of water is approaching that level where it would form the continuous phase. Conversely, if the water is added with or before the solvent, it will tend to form the continuous phase.
  • a primary function of the water is to provide energy to aid the vaporization of the solvent during flashing since it is not desirable to have the temperature so high that there is sufficient energy imparted to the solvent alone to effect its complete vaporization.
  • the amount of water should not be so great as to require the expenditure of unnecessary heat values in attaining the desired flashing temperature, i.e., once that amount of water required to form an aqueous solution or dispersion of the agent having a suitable viscosity is determined, additional water may be employed to a certain extent since it helps to lower the mixture viscosity and aids solvent vaporization but the additional amount need not be great.
  • Another function of the water is to reduce the temperature of the fibrous mass in the zone immediately following the nozzle (flash zone).
  • the addition of water increases the total vapor pressure of the system at the moment of flashing thus reducing the boiling point of the flashing mixture.
  • This is independent of the amount of water employed, and very small quantities may thus be employed for this purpose.
  • water would be employed in the amount of at least about 1% by volume of the solvent-water mixture. Lowering the boiling point of the mixture in this fashion will assist in establishing proper temperature conditions in the fibrous mass formed upon flashing in accordance with this invention, as discussed in detail at a later point.
  • Another function of the water is to act as the carrier for a hydrophilic water-dispersing agent for the fibers to be formed. It has been found that it is most advantageous to have the water-dispersing agent present during flashing and precipitation of the fibrous polymer. An equivalent amount of the same agent added at a later stage to the already formed fibers does not give the same degree of dispersibility and the presence of the agent enhances the refinability of the fibers. Therefore, the water should be present in an amount sufficient to carry that amount of the hydrophilic agent employed to impart to the fibrous polymer the desired level of water dispersibility, preferably as a solution thereof.
  • Additional water above such minimum amount required to carry the agent may be employed to impart a suitable viscosity to the aqueous solution or dispersion agent, i.e., the aqueous solution of the water-dispersion agent should not be so viscous as to present problems of han dling or incorporation into the polymer solution as a dispersed phase.
  • the water can aid in reducing the viscosity of the mixture to a level less than that of the polymer solution alone, thus permitting higher polymer concentrations.
  • the agents which may be added to the mixture to impart water dispersibility to the fibrous polymer are preferably Water soluble, or partially water soluble, high molecular weight materials. However, they may also be materials which are soluble or partially soluble in the solvent so long as they are somewhat hydrophilic and impart water dispersibility to the fibers.
  • the amount of water-dispersing agent employed may range from about 0.1% to about by weight of the polymer, preferably from about 0.1% to about 5% by weight.
  • the preferred waterdispersing agent is an at least partially water-soluble polyvinyl alcohol (PVA) having a degree of hydrolysis greater than about 77% and, preferably, greater than about 88 mo].
  • the PVA has a degree of polymerization in the range of 200 to 4,000 and preferably between 300 and 1,500. If desired, the PVA may be chemically modified to enhance its adhesion to the polymer, dispersion and other properties.
  • the polyvinyl alcohol is preferably added with the water at the time the mixture is formed.
  • Illustrative of other water-dispersing agents that may be employed are cationic guar, cationic starch, potato starch, methylcellulose and Lytron 820 (a styrene-maleic acid copolymer).
  • Such water-dispersing agents are also advantageous in developing the fiber properties during refining of the flashed product in accordance with this invention, as described at a later point.
  • such agents may be added subsequent to flashing, such as with the dilution water for refining. It is particularly advantageous to add at least 0.75% and preferably between about 1 /z% and 5% by weight of the flashed polymer of polyvinyl alcohol, either before and/or after flashing (but prior to refining).
  • the ingredients of the mixture can be placed in any suitable vessel which is capable of being heated to an elevated temperature and pressure. Generally, an autoclave is employed. However, when water is added as a flashing aid it is important that the vessel employed be equipped with a mixing or stirring device capable of keeping the mixture in a constant state of agitation since a stable emulsion is not formed and upon standing the mixture will quickly separate into two distinct and separate phases.
  • the ingredients are then heated to a suitable temperature and preferably agitated if water is present to form a uniform mixture wherein Water is present as a discontinuous or dispersed phase within a continuous phase of polymer solution or as a continuous phase with polymer solution dispersed uniformly therein, depending upon the water concentration and mode of addition, as previously discussed.
  • the temperature employed is preferably above the melt dissolution temperature of the polymer in the solvent employed.
  • the melt dissolu tion temperature of any particular solvent is determined by placing low concentrations of the polymer (e.g., 0.1 and 1.0% by weight) into the solvent in a vial which is then sealed and placed in an oil bath. The temperature of the oil bath is raised slowly (e.g., 10 C/hr) until the last trace of polymer disappears.
  • This temperature is the melt dissolution temperature. In some instances, it may be desirable to operate at a temperature below the melt dissolution temperature. In this case the temperature should be high enough under the operating conditions so that the polymer is dissolved in the solvent or at least is in a swollen state with sufficient fluidity to be discharged from the nozzle, i.e., in a plastic state.
  • Flashing is preferably carried out substantially adiabatically, utilizing the heat (enthalpy) in the heated mixture to provide the heat of vaporization for vaporizing substantially all of the solvent when the mixture is discharged to the flash zone held at a suitable lower pressure.
  • the temperature of the mixture prior to flashing should be high enough to provide sufficient heat content or enthalpy for vaporization adiabatically of substantially all solvent upon flashing to the flash zone.
  • the maximum temperature employed should be less than the critical temperature of the solvent and/or the decomposition temperature of the polymer.
  • the flashing it is also possible to carry out the flashing to some extent in a nonadiabatic fashion, for example, by the addition of heat to the material as it is flashed from the nozzle.
  • low pressure steam e.g., below 20 psig
  • water at about 100 C. may be added to the fibrous noodle in the flashing zone as by injection thereof in a conduit immediately following the flash nozzle into which the flashed noodle is also injected.
  • the flashing temperature should be chosen so the heat content in the mixture to be flashed plus the heat added to the flashed material is sufficient to vaporize substantially all of the solvent in the flash zone.
  • the pressure employed in the vessel containing the heated mixture is preferably substantially autogenous although pressures higher than autogenous may be employed. It may be desirable, particularly in batch operations, to employ an inert gas such as nitrogen during the flashing operation to maintain substantially autogenous pressure in the vessel and thus maintain the velocity of the mixture through the nozzle at a fairly constant level.
  • Flashing is preferably effected through a nozzle which has a substantial longitudinal dimension in order to efficiently impart shear to the mixture (particularly the polymer component thereof) immediately prior to flashing. Such shearing action aids fiber formation and enhances fiber properties for papermaking purposes.
  • the nozzle may be circular or noncircular in crosssection and may be an annulus.
  • the flash zone is maintained at a pressure which, in conjunction with the other conditions of flashing are selected so that the temperature of the flashed product is almost immediately lowered in the flash zone, by evaporation of substantially all of the solvent (and a portion of the flashing aids, if employed), to a tempera ture below the softening temperature of the polymer, preferably below about 100 C., but above the boiling temperature of the solvent(s) employed and preferably above about C.
  • vaporization may be substantially complete 10 to cm downstream of the nozzle. However, this can vary widely depending on the flow veloc ity, flash zone pressure, flash temperature, solvent, etc.
  • all of the components of the mixture and the concentration of each in the mixture are chosen with respect to the heat capacity of each, with respect to the heat of vaporization of each component which will be volatilized in flashing, and with respect to the flash temperature chosen so as to produce in the flashed product a temperature above the boiling point of the solvent and preferably between about 70 C. and about 100 C. upon flashing of the mixture into the flash zone.
  • the heat content of the mixture to be flashed and the heat to be removed through vaporization of the vaporizable components (solvent and any flashing aids vaporized, if employed) should be adjusted so that the residual heat in the flashed product, after removal of the heat of vaporization of the vaporized components, will impart a temperature in the flashed product which is between about 70 C. and 100 C. Selection of the appropriate flashing temperature and of the components of the mixture and their concentrations for this purpose will depend upon the pressure selected for the flash zone and the amount of heat added to the flash material during flashing if the flashing is performed nonadiabatically.
  • the flash zone is at substantially atmospheric pressure, i.e., between about 600 and 800 mm Hg.
  • variable parameters namely, the flash temperature, components and concentrations thereof in the flash mixture, may be determined for a given pressure condition in the flash zone by making a heat balance for the flashing operation which will produce the desired noodle temperature below 100 C.
  • these variable parameters may be selected so as to satisfy the following equation:
  • the heat capacity values and Weights of the flash components may be substituted into this formula, for example, as follows for the specific case where a single polymer, solvent and flashing aid are present in the flash mixture:
  • the heat capacity and enthalpy of vapori zation values for the desired components can be substituted into this equation.
  • a flash temperature and the concentrations of the flash mixture components may be selected relative to each other to satisfy the equation for a desired flashed product temperature.
  • the various parameters should also satisfy the other conditions for proper flashing as previously discussed, e.g., the flash temperature should be above the melt dissolution temperature, substantially all of the solvent should be vaporized, etc.
  • the temperature of the fibrous product or noodle can be raised to this range by suitable means prior to primary refining.
  • primary refining is carried out at a temperature above the boiling point of the solvent and preferably within the range of about 70 C. to 100 C. in order to vaporize any residual solvent left in the noodle.
  • the polymer is precipitated as a fi' brous product or noodle," which is a loose aggregation of fibers which is usually continuous.
  • the fibrous product is collected in a suitable receiving vessel, preferably one which permits the vaporized solvent to be separated therefrom.
  • the fibrous product in the receiving vessel may be either substantially dry if flashed from a polyolefin solution or as an aqueous slurry if flashed from a dispersion -or emulsion employing water as a flashing aid.
  • a certain amount of unflashed residual solvent will remain with the fibrous product and it is therefore important that the temperature of the fibrous product be kept high enough to continue the vaporization of the solvent.
  • the present invention resides in the discovery that similarly improved products can be obtained with a smaller amount of retained solvent by carrying out the refining of the fibrous product while it is maintained at an elevated temperature above the boiling point of the solvent if the fibrous product first passed through a primary refining zone under conditions such that only a light defibering or shredding action is imparted to the fibrous product.
  • defibering or shredding action it is meant that the noodle is subjected to forces just sufficient to pull it apart into a fibrous mass which, at a consistency between about 1% and 10% by weight, is pumpable. If the fibrous product is subjected to more than such light defibering or shredding action while at elevated temperatures, the ultimate fiber and sheet properties are detrimentally affected, as will be shown in the examples.
  • dilution water Prior to passing the fibrous product through such primary refining zone, dilution water is added to the receiving vessel to provide an aqueous slurry of the fibrous product having an appropriate consistency.
  • the consistency of the aqueous slurry is between about 1 to 10% by weight of the fibrous material, although high consistencies between about l0% and 60% by weight may be employed by using screw feeding or similar feeding means.
  • the dilution water temperature should be such as to provide an aqueous slurry of noodle having a temperature above the boiling point of the solvent at the pressure employed (normally 1 atmosphere), and preferably between about 70C. and 100 C,
  • the primary refining zone is a disc refiner of the type conventionally employed in the papermaking art and may be a single or double rotating disc refiner. However, the refiner is operated to impart only a light defibering or shredding action to the fiberous product passing therethrough. This is accomplished by preferably employing plates having narrow bars, that is, bars having a width up to about 0.5 inch, and by spacing the plates relatively far apart, that is, a plate clearance distance between about 0.1 and 0.25 inch. The moving disc or discs are rotated at speeds to provide relative peripheral velocities between about 4,000 and 8,000 feet per minute. The size of the discs may be any of those normally employed in the papermaking art.
  • the defibering or shredding action referred to may be characterized by the amount of fibrous material rctained on the plus 35-mesh screens after primary refining when the fibrous material is classified in accordance with TAPPl Standard Test T-233 SU64. At least about 90% of the fibrous material should be retained on the 20 plus 35-mesh screens; if less than this amount is retained, the refining action has been too vigorous. Generally, the amount of work done on the fibrous material during primary refining will be less than about 0. l kilowatt-hour/kilogram.
  • the primary refining is preferably accomplished by use of a disc refiner as discussed above, it may be accomplished in other devices such as Claflin refiners, Hollander beaters, Dynapulpers, hydrapulpers, etc., it only being necessary to impart a defibering or shredding action which will still permit at least about 90% of the fibrous material to be retained on a 20 plus 35-mesh screen.
  • the aqueous slurry of fibrous product resulting from the primary refining operation drops from the bottom of the disc refiner into a receiving vessel which may be purged with an inert gas such as nitrogen to remove solvent vaporized during the primary refining step.
  • the fibrous product is preferably cooled to a temperature below C. by any suitable method, such as use of cooling coils, adding dilution water or sitting, and the cooled pulp is then subjected to secondary refining.
  • the pulp may be cooled and thickened for storage and/or shipment, and the secondary refining may be accomplished at a much later date with the same beneficial results.
  • the secondary refining is preferably carried out in a disc refiner employing refiner conditions which impart a vigorous fibrillating action to the fibrous product which optimizes the fiber papermaking characteristics.
  • the precise conditions employed in this secondary refining need not be gone into in detail since the skilled papermaker can optimize the type of plates, disc spacing, disc velocity and power output to develop optimum properties for the particular product to be produced from the fibers.
  • the secondary refining may be carried out with refiner plates having a plate spacing less than 0.1 inch (2500 microns), and desirably between about zero and 0.01 inch (250 microns), and a disc peripheral velocity of between about 4,000 and 8,000 feet per minute. Multiple passes through one or more refiners may be employed. Instead of disc refiners, one may employ any conventional refining device and refine the pulp in a known manner to optimize properties.
  • the secondary refining is conducted under conditions such that the drainage factors of the resulting pulp is greater than l.O seconds/grams. Also, after secondary refining the pulp will be retained to the extent of less than and generally less than 50% by weight on the 20 plus 35-mesh screens.
  • a pulp is produced having superior qualities.
  • one indication of the improvement of the fibers made by the process of the present invention is the drainage factor of such fibers as compared to fibers of similar classified fiber length which are made using parameters outside the present invention.
  • the drainage factor is a measure of the drainage characteristics of a fiber when a slurry thereof is placed on a foraminous surface.
  • important strength properties thereof correlate generally with their drainage factor.
  • various strength properties of paper made therefrom increase with the drainage factor of such fibers.
  • Another indication of improvement of the fibers made in accordance with this invention is their slenderness relative to fibers prepared by typical conventional technique. It is desirable to produce fibers which are relatively thin (or of low coarseness) as these fibers will impart higher opacity, density and better formation to the paper prepared therefrom.
  • the set of operating parameters of the present invention will result in improved fiber properties such as thinness and drainage factor compared with fibers prepared using typical conventional parameters. Because other process variables in addition to the specific parameters of this invention also influence fiber properties (e.g., flash nozzle size and configuration, polymer type and molecular weight, solvent, flashing aids, dispersants, etc.), such resulting fiber comparisons are appropriately made with the other process variables held constant.
  • fiber properties e.g., flash nozzle size and configuration, polymer type and molecular weight, solvent, flashing aids, dispersants, etc.
  • pulps can be produced in accordance with this invention which have a drainage factor in excess of l and as high as 50 to 100 seconds per gram and which have an average coarseness below 15 decigrex (as measured by TAPPI Text 234 SU 67) and frequently between 1 and I decigrex (m/lOO m).
  • a drainage factor between 2 and may be the preferred range as an appropriate balance between increased strength and ease of water removal from the fibers. Higher drainage factors can be obtained and may be useful where the enhanced strength is more important than rapid water removal.
  • FIG. 1 represents a schematic representation of apparatus suitable for use in carrying out the process of this invention
  • FIG. 2 is a detailed representation of the flash nozzle schematically shown in FIG. 1.
  • l is a steam-jacketed vessel, provided with an agitator In, which may be charged with solvent, polymer (or polymer solution) and, if desired, flashing aids such as water.
  • Conduit 2 is provided at the bottom of vessel 1 in communication with flash nozzle 3 through shut-off valve 4 (preferably a ball valve).
  • shut-off valve 4 preferably a ball valve.
  • flash nozzle 3 has a substantially smaller diameter than conduit 2.
  • nitrogen or other inert gas may be introduced into the head space thereof through line 5 in order to maintain the pressure in the vessel at autogenous or higher pressure.
  • the mixture is flashed through nozzle 3 into the flash zone which is comprised of a vapor separation vessel such as cyclone 6, and connecting conduit 7.
  • Conduit 7 is a pipe having an internal cross-sectional area larger than that of flash nozzle 3 and of sufficient internal diameter to permit rapid, unrestricted passage of the flashed noodle to eyclone 6 and preferably has an internal cross-sectional area many times larger than that of the nozzle 3.
  • low pressure steam may be introduced into conduit 7 through line 8 located shortly beyond flash nozzle 3 to aid in the vaporization of solvent from the precipitated noodle.
  • Vaporized solvent and water leaving cyclone 6 pass through line 21 to a solvent recovery unit (not shown).
  • Conduit 11 is provided for introduction of dilution water at an appropriate temperature to form a mixture or slurry with the fibrous material having an appropriate consistency for disc refining.
  • the lightly shredded material leaving the primary refiner 10 passes through conduit 12 to first receiving tank 13. Nitrogen is introduced into tank 13 through line 14 which sweeps out solvent vapors which are removed via suitable means not shown.
  • the water slurry of refined fibers is cooled, either by letting the slurry sit in tank 13 for an appropriate time or by other means.
  • the slurry may be withdrawn from receiving tank 13 through line 15 utilizing pump 16, for secondary refining in disc refiner 17.
  • the fibrous slurry leaving secondary refiner 17 passes through conduit 18 to second receiving tank 19 where it is collected prior to further processing for shipment or for papermaking use. If desired, the fibrous slurry leaving refiner 17 may be recycled through line 20 for one or more additional passes through refiner 17.
  • the fibers after refining may be diluted to a suitable consistency and made into synthetic paper webs, either alone or blended with normal cellulose papermaking fibers. Alternatively, the fibers can be dewatered, pressed into bales, stored and shipped to the ultimate user.
  • the secondary refining previously referred to can be carried out by the ultimate user
  • the illustrated apparatus may be operated on a batch basis as described or on a continuous basis by continuously feeding vessel 1 with polymer solution and any flashing aids desired at flow rates to maintain the appropriate mixture in the vessel for flashing, while heating the vessel to maintain the mixture at the appropriate flash temperature. In order to insure unifrom dispersion of flashing aids, it may be desirable to place an in-line mixing device in line 2 between vessel 1 and flash nozzle 3.
  • a stirred heated vessel such as vessel 1
  • EXAMPLE I The apparatus employed in this example is that illustrated in the drawing and previously described.
  • the dissolution vessel 1 was a two-gallon stirred autoclave equipped with five 4-inch impellers on a single shaft rotated at 1,000 rpm.
  • the vessel was charged with ().32 Kg of polyethylene (Mitsui 22()()P) having an intrinsic viscosity )1;) of L4 dl/gram and 4.0 liters of n-hexane.
  • the vessel was sealed and the contents raised to a temperature of 143 C.
  • the vessel was pressurized with nitrogen to maintain a pressure of 160 psig.
  • the heated contents were then flashed through a nozzle 3 having a diameter of 0.07 inch 1.75 mm) and a length of 1 Vs inches (28.125 mm) into receiving vessel 6.
  • Low pressure steam psig was introduced into conduit 7 via line 8 at a point 3 inches downstream of nozzle 3.
  • Dilution water at a temperature of 93 C. was introduced into receiving vessel 6 to provide a slurry having a consistency of about 1.0% by weight and a temperature between 85 C. and 93 C.
  • the aqueous fibrous slurry was then passed through a primary refining zone consisting of a Sprout Waldron single disc refiner having 12-inch plates (Pattern C29-78B) and a plate clearance of 0.150 inch.
  • the moving disc was operated at 1,750 rpm (peripheral velocity of 5,495 feet per minute).
  • the refiner had been preheated with dilution water and steam before refiner start-up and setting of plate clearances.
  • the pulp slurry was then subjected to secondary refining by passing it at a temperature of 76-80 C. once through the same disic refiner with the plate spacing set at 0.025 inch and once through at 0.010 inch, then twice through at 0.002 inch.
  • the resulting pulp had a drainage factor of 4.6 seconds/gram and a fiber fraction on the plus 35-mesh screen of 38.4% l-Iandsheets were made from the pulp in accordance with TAPPI Standard Test T-205M-58 with modified wet pressing (400 psig).
  • the handsheets were tested and had the following properties:
  • the Scott lnternal Bond was determined by employing the Scott instrument under the standard procedure.
  • the drainage factor in this and following examples was determined substantially in accordance with TAPPI Test T221 05-63 with a slight modification in the method of calculation. Briefly, approximately ten grams of a fiber sample is weighed and dispersed in water. The slurry is then added to the standard sheet mold and water added to the mark. The slurry is stirred by four up-and-down strokes of the standard stirrer, which is then removed. The water temperature in the mold is measured and the drainage valve opened. The time between the opening of the valve and the first sound of suction is noted. The procedure is repeated with water only (no fiber) in the sheet mold and the temperature and drainage time noted. The drainage factor in seconds per gram is then calculated as follows:
  • Example 1 In order to show the improvement in fiber properties obtained by subjecting a fibrous noodle to a light defibering action at an elevated temperature rather than a rigorous fibrillating action, Example I was repeated, except that the primary refining was accomplished by passing the fibrous noodle through the refiner with the plates set only 0.005 inch apart. The pulp was then passed once through a secondary refining zone as in Example 1. The resulting pulp had a fiber fraction on the 20 plus 35-mesh screen of 36.4% and a drainage factor of only 1.4 seconds/gram compared to 4.6 seconds/gram for the pulp of Example 1. The lower drainage factor is indicative of a fiber which will form a much weaker sheet, as shown from the handsheet data set forth in the following table. The handsheets were made as in Example 1:
  • EXAMPLE 3 EXAMPLE 4 The same general procedure as employed in Example 1 was repeated employing a polyvinyl alcohol made by Farbwerke Hoechst AG (Moviol 75-88) that is 88% bydrolyzed and has a viscosity (4% by weight aqueous solution at 20 C.) of 20-25 centipoises. Runs 1 and 2 were subjected to primary refining in the refiner described in Example 1 at a plate clearance of 0.150 inch. Run 1 was subjected to one pass of secondary refining at a plate clearance of 0.005 inch and two passes of secondary refining at a plate clearance of 0.002 inch at a temperature of 77-80 C.
  • a polyvinyl alcohol made by Farbwerke Hoechst AG (Moviol 75-88) that is 88% bydrolyzed and has a viscosity (4% by weight aqueous solution at 20 C.) of 20-25 centipoises.
  • Runs 1 and 2 were subjecte
  • Run 2 was subjected to one pass of secondary refining at a plate clearance of 0.005 inch and three passes of secondary refining at a plate clearance of 0.002 inch at a temperature of 3341 C.
  • Run 3 was subjected to one pass of primary refining at a plate clearance of 0.005 inch.
  • Handsheets (both 100% and 50/50 blends) were made and tested as in Example 1. The properties of the fibers and handsheets were as follows:
  • Example 2 The same general procedure as employed in Example 1 was repeated employing a polyvinyl alcohol made by Farbwerke Hoechst AG (Moviol 75-98) that is 98% hydrolyzed and has a viscosity (4% by weight aqueous solution at 20 C.) of 25-30 centipoises.
  • Runs l and 2 were subjected to primary refining in the refiner described in Example 1 at a plate clearance of 0.150 inch.
  • Run 1 was subjected to one pass of secondary refining at a plate clearance of 0.005 inch and two passes Comparison Property Run l Run 2 Run 3 Drainage Factor. sec/g. 3.2 5.2 1.5
  • Example 6 Kg-cm/cm X 10 158 164 174 704 703 707 Scattering Cocfiiciem EXAMPLE 7
  • Example 6 was repeated except that 5% by weight polyvinyl alcohol (based on the weight of the polyethylene) was employed in the dissolution vessel rather than 2%. After one pass of primary refining at a plate clearance of 0.250 inch and one pass of secondary refining at a clearance of 0.005 inch the resulting pulp had a drainage factor of 15.7 seconds/gram.
  • This example illustrates that higher percentages of the'aqueous disas in Example 1.
  • the properties of the fibers and handpersing agent polyvinyl alcohol may be employed, if desheets were as follows: sired.
  • a method of producing a pulp of polyolefin fibers wherein a solution or dispersion of a polyolefin in a solvent at an elevated temperature and pressure is flashed through a nozzle into a zone of reduced pressure to form a fibrous product, the improvement comprising diluting the fibrous product with water to a consistency between about 1% and 10% by weight while maintaining the fibrous product above the boiling point of said solvent at a temperature between about C.

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Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3976631A (en) * 1973-04-18 1976-08-24 Stamicarbon B.V. Process for preparing ethylene polymers
US4010229A (en) * 1974-01-18 1977-03-01 Solvay & Cie Process for the manufacture of short fibrils
US4054625A (en) * 1972-08-30 1977-10-18 Crown Zellerbach Corporation Process for making fibers
US4069287A (en) * 1974-01-31 1978-01-17 Compagnie Francaise De Raffinage Process for the production of polyolefin fibers
US4216281A (en) * 1978-08-21 1980-08-05 W. R. Grace & Co. Battery separator
US4260565A (en) * 1973-10-02 1981-04-07 Anic S.P.A. Process for the production of fibrous structures
US4265985A (en) * 1978-08-21 1981-05-05 W. R. Grace & Co. Lead acid battery with separator having long fibers
EP0292285A1 (en) * 1987-05-19 1988-11-23 E.I. Du Pont De Nemours And Company Polyethylene pulp
US5047121A (en) * 1990-09-20 1991-09-10 E. I. Du Pont De Nemours And Company High grade polyethylene paper
US5786284A (en) * 1993-04-08 1998-07-28 Unitika, Ltd. Filament having plexifilamentary structure, nonwoven fabric comprising said filament and their production
US6156680A (en) * 1998-12-23 2000-12-05 Bba Nonwovens Simpsonville, Inc. Reverse osmosis support substrate and method for its manufacture
US6171443B1 (en) * 1990-03-05 2001-01-09 Polyweave International, Llc Recyclable polymeric synthetic paper and method for its manufacture
US20060003154A1 (en) * 2004-06-30 2006-01-05 Snowden Hue S Extruded thermoplastic articles with enhanced surface segregation of internal melt additive
US20060003167A1 (en) * 2004-06-30 2006-01-05 Kimberly-Clark Worldwide, Inc. Synergistic fluorochemical treatment blend
US20070219287A1 (en) * 2006-03-16 2007-09-20 Hollister Incorporated Hydrocolloid-containing adhesive composition having network of fibrillated polymeric fibers
US20100247908A1 (en) * 2009-03-24 2010-09-30 Velev Orlin D Nanospinning of polymer fibers from sheared solutions
US20120216975A1 (en) * 2011-02-25 2012-08-30 Porous Power Technologies, Llc Glass Mat with Synthetic Wood Pulp
US9217211B2 (en) 2009-03-24 2015-12-22 North Carolina State University Method for fabricating nanofibers
US9217210B2 (en) 2009-03-24 2015-12-22 North Carolina State University Process of making composite inorganic/polymer nanofibers
US11306214B2 (en) 2016-05-09 2022-04-19 North Carolina State University Fractal-like polymeric particles and their use in diverse applications

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5246102A (en) * 1975-09-12 1977-04-12 Asahi Chemical Ind Process for dispersing fibrous material
JPS5920490A (ja) * 1982-07-22 1984-02-02 Nippon Kokan Kk <Nkk> 亜鉛合金めつき鋼板およびその製造法
JPS6039191A (ja) * 1983-08-11 1985-02-28 Nippon Steel Corp 加工性に優れたΖｎ−Ｆｅ−Ｃｏ合金めつき鋼板

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US3047455A (en) * 1959-03-13 1962-07-31 Monsanto Chemicals Paper manufacture from synthetic non-cellulosic fibers
US3382140A (en) * 1966-12-30 1968-05-07 Crown Zellerbach Corp Process for fibrillating cellulosic fibers and products thereof
US3436304A (en) * 1965-05-19 1969-04-01 Dow Chemical Co Method for manufacturing nonwoven fibrous products from gel fibers
US3445329A (en) * 1966-03-14 1969-05-20 Crown Zellerbach Corp Storage of high consistency refined pulp
US3743272A (en) * 1971-04-12 1973-07-03 Crown Zellerbach Corp Process of forming polyolefin fibers
US3743570A (en) * 1971-03-03 1973-07-03 Crown Zellerbach Corp Process for producing a nonwoven fabric web from a suspension of polyolefin fibers and a hydrophilic colloidal polymeric additive
US3770856A (en) * 1970-09-08 1973-11-06 Oji Yuka Goseishi Kk Production of fine fibrous structures

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JPS5247049A (en) * 1975-10-11 1977-04-14 Mitsubishi Chem Ind Ltd Flame retardant polycarbonate resin composition

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3047455A (en) * 1959-03-13 1962-07-31 Monsanto Chemicals Paper manufacture from synthetic non-cellulosic fibers
US3436304A (en) * 1965-05-19 1969-04-01 Dow Chemical Co Method for manufacturing nonwoven fibrous products from gel fibers
US3445329A (en) * 1966-03-14 1969-05-20 Crown Zellerbach Corp Storage of high consistency refined pulp
US3382140A (en) * 1966-12-30 1968-05-07 Crown Zellerbach Corp Process for fibrillating cellulosic fibers and products thereof
US3770856A (en) * 1970-09-08 1973-11-06 Oji Yuka Goseishi Kk Production of fine fibrous structures
US3743570A (en) * 1971-03-03 1973-07-03 Crown Zellerbach Corp Process for producing a nonwoven fabric web from a suspension of polyolefin fibers and a hydrophilic colloidal polymeric additive
US3743272A (en) * 1971-04-12 1973-07-03 Crown Zellerbach Corp Process of forming polyolefin fibers

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4054625A (en) * 1972-08-30 1977-10-18 Crown Zellerbach Corporation Process for making fibers
US3976631A (en) * 1973-04-18 1976-08-24 Stamicarbon B.V. Process for preparing ethylene polymers
US4260565A (en) * 1973-10-02 1981-04-07 Anic S.P.A. Process for the production of fibrous structures
US4010229A (en) * 1974-01-18 1977-03-01 Solvay & Cie Process for the manufacture of short fibrils
US4069287A (en) * 1974-01-31 1978-01-17 Compagnie Francaise De Raffinage Process for the production of polyolefin fibers
US4265985A (en) * 1978-08-21 1981-05-05 W. R. Grace & Co. Lead acid battery with separator having long fibers
US4216281A (en) * 1978-08-21 1980-08-05 W. R. Grace & Co. Battery separator
EP0292285A1 (en) * 1987-05-19 1988-11-23 E.I. Du Pont De Nemours And Company Polyethylene pulp
AU603670B2 (en) * 1987-05-19 1990-11-22 E.I. Du Pont De Nemours And Company Improved polyethylene pulp
US5000824A (en) * 1987-05-19 1991-03-19 E. I. Du Pont De Nemours And Company Polyethylene pulp
US6171443B1 (en) * 1990-03-05 2001-01-09 Polyweave International, Llc Recyclable polymeric synthetic paper and method for its manufacture
US5047121A (en) * 1990-09-20 1991-09-10 E. I. Du Pont De Nemours And Company High grade polyethylene paper
EP0477019A3 (en) * 1990-09-20 1992-09-23 E.I. Du Pont De Nemours And Company High grade polyethylene paper
US5786284A (en) * 1993-04-08 1998-07-28 Unitika, Ltd. Filament having plexifilamentary structure, nonwoven fabric comprising said filament and their production
US5795651A (en) * 1993-04-08 1998-08-18 Unitika, Ltd. Filament having plexifilamentary structure, nonwoven fabric comprising said filament and their production
US6156680A (en) * 1998-12-23 2000-12-05 Bba Nonwovens Simpsonville, Inc. Reverse osmosis support substrate and method for its manufacture
US7781353B2 (en) 2004-06-30 2010-08-24 Kimberly-Clark Worldwide, Inc. Extruded thermoplastic articles with enhanced surface segregation of internal melt additive
US20060003167A1 (en) * 2004-06-30 2006-01-05 Kimberly-Clark Worldwide, Inc. Synergistic fluorochemical treatment blend
US7285595B2 (en) 2004-06-30 2007-10-23 Kimberly-Clark Worldwide, Inc. Synergistic fluorochemical treatment blend
US20090197039A1 (en) * 2004-06-30 2009-08-06 Kimberly-Clark Worldwide, Inc. Extruded Thermoplastic Articles with Enhanced Surface Segregation of Internal Melt Additive
US20060003154A1 (en) * 2004-06-30 2006-01-05 Snowden Hue S Extruded thermoplastic articles with enhanced surface segregation of internal melt additive
US20070219287A1 (en) * 2006-03-16 2007-09-20 Hollister Incorporated Hydrocolloid-containing adhesive composition having network of fibrillated polymeric fibers
US7767291B2 (en) 2006-03-16 2010-08-03 Hollister Incorporated Hydrocolloid-containing adhesive composition having network of fibrillated polymeric fibers
US9217211B2 (en) 2009-03-24 2015-12-22 North Carolina State University Method for fabricating nanofibers
US8551378B2 (en) 2009-03-24 2013-10-08 North Carolina State University Nanospinning of polymer fibers from sheared solutions
US9217210B2 (en) 2009-03-24 2015-12-22 North Carolina State University Process of making composite inorganic/polymer nanofibers
US20100247908A1 (en) * 2009-03-24 2010-09-30 Velev Orlin D Nanospinning of polymer fibers from sheared solutions
US20120216975A1 (en) * 2011-02-25 2012-08-30 Porous Power Technologies, Llc Glass Mat with Synthetic Wood Pulp
US11306214B2 (en) 2016-05-09 2022-04-19 North Carolina State University Fractal-like polymeric particles and their use in diverse applications
US12209203B2 (en) 2016-05-09 2025-01-28 North Carolina State University Fractal-like polymeric particles and their use in diverse applications

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JPS5029821A (enrdf_load_stackoverflow) 1975-03-25

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