US3345445A - Melt spinning process of polyamides - Google Patents

Melt spinning process of polyamides Download PDF

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Publication number
US3345445A
US3345445A US352394A US35239464A US3345445A US 3345445 A US3345445 A US 3345445A US 352394 A US352394 A US 352394A US 35239464 A US35239464 A US 35239464A US 3345445 A US3345445 A US 3345445A
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United States
Prior art keywords
chips
polymer
tumbler
melt spinning
spinning
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US352394A
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English (en)
Inventor
Siclari Francesco
Bellano Angelo
Maderno Cesano
Ciceri Luigi
D Alo Bruno
Perazzoni Pierluigi
Giacobone Emilia Manfred Widow
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SNIA Viscosa SpA
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SNIA Viscosa SpA
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    • 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
    • D01D1/00—Treatment of filament-forming or like material
    • D01D1/10—Filtering or de-aerating the spinning solution or melt
    • D01D1/103—De-aerating
    • 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
    • D01D1/00—Treatment of filament-forming or like material
    • D01D1/04—Melting filament-forming substances
    • 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
    • D01D1/00—Treatment of filament-forming or like material
    • D01D1/06—Feeding liquid to the spinning head
    • 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

  • the present invention relates to an improvement in the processes for the melt spinning of polyamides and particularly of polycaproamides, that is of caprolactam polymer, normally known as nylon 6.
  • melt spinning of polyamides and particularly of nylon 6 the polymer is usually prepared in form of chips which are subjected to a very thorough drying. The dried chipsare then put into a tank from which they are continuously fed to a melt-spinning head of any known type, for example of the type described in the Italian Patent of du Pont 'No. 376,200 or in the Italian patent of the applicants No. 492,712, or alternatively to a screw type apparatus for melt spinning or to any other known type of melt spinning apparatus.
  • spinning is efiected under at atmosphere of inert gas preferably under nitrogen, which is usually allowed to flow through the spinning head, and fills the feed tank of the spinning head.
  • Drying is normally carried out at 0.1 mm. Hg vacuum and at a temperature between 80 C. and 110 C. until the residual humidity of the chips is not more than 0.15%
  • one of the main problems in melt spinning is to obtain yarns of regular characteristics concerning some properties, particularly the morphological properties i.e. the regularity of the count, and the chemical aflinity for dyes, i.e. the regularity of dyeing properties.
  • the polymer is charged into the tank of the spinning apparatus at a temperature not more than 50 C. and preferably between 25 and 30 C.
  • the temperatures indicated in the present invention would therefore represent critical values, below which the number of the polymer end groups becomes stable and cannot be affected by-subsequent inevitable treatments prior to the melting of the chips.
  • the treated polymer is nylon 6 obtained by the polymerization of caprolactam by the known methods.
  • Such polymer is a polyamide that shows a minimum intrinsic viscosity of 0.85 in a m-cresol solution at 20 C. and preferably an intrinsic viscosity comprised between 1.0 and 1.30 which corresponds to a ponderal average molecular weight, calculated with the formula Mfl:16600(!]) (Grieth e Sieber, Faserforshuug und Textiltecknik 6 32, 1955), between 17,300 and 26,000.
  • the polymer is obtained in the form of chips of suitable size which are fed to a melt spinning head by any known method.
  • the polymer can be meltextruded as a filament with a 3 to 4 mm. diameter, and said filament can be cut into chips of the magnitude of 2 to 6 mm., or the polymer can be extruded in the form of a ribbon or of sheets, which are then suitably chopped
  • the chips have generally a weight of between 0.005 and 0.04 gr.
  • Said chips, which are considered as starting material according to the present invention are subjected to normal drying, which is carried out under vacuum and at not very high temperatures so as to prevent the oxidation and degradation of the polymer.
  • vacuum is maintained between 0.05 and 0.2 mm. Hg and temperature between C. and C.
  • FIG. 1 is a longitudinal section of a drying apparatus
  • FIG. 2 is a diagrammatic view illustrating how the hot and dried chips may be cooled outside the tumbler of FIG. 1;
  • FIG. 3 is a diagrammatic view illustrating another type of apparatus for cooling the chips.
  • FIG. 4 is a vertical sectional view of the feed tank into which the cooled chips are delivered, and the spinning head connected thereto.
  • FIG. 1 there is shown a rotative tumbler 10 provided with a heating jacket 11, a hatchway 12 for the charge and discharge of the chips and a manometer 13.
  • the tumbler is held eccentrically at two diametrically opposite ends by trunnions 14 and 15, of which the trunnion 15 is provided with a pulley 16 connected to a motor which is not illustrated.
  • hot water is caused to circulate from a boiler, not shown in the figure, through the valve 17, the coaxial tube 18 and the feeding tube 19 into the jacket 11.
  • the hot water penetrates into the jacket 11 at point 20, comes out through the discharge pipe 21, the coaxial tube 22 and the valve 23, and is then recycled.
  • the tumbler is connected to a vacuum pump, not shown in the figure, through the coaxial piping 24 and the valve 25.
  • the cooling phase is started, cold or suitably cooled water being introduced into the jacket 11 through valve 26 and pipings 18, 192, 20, 21, 22; it then comes out through the valve 27.
  • the vacuum pump is detached from the tumbler by closing the valve 25; the reduced pressure in the tumbler is raised to atmospheric pressure by introducing an inert gas, for instance nitrogen with controlled humidity not more than 70 mgr./m. through the valve 28 and the same coaxial tube 24.
  • an inert gas for instance nitrogen with controlled humidity not more than 70 mgr./m.
  • drying can be carried out at 80 C. and at reduced pressure of 0.1 mm. Hg over a period of about 30 hours.
  • the cooling of hot and dried chips can also be achieved outside of the tumbler by other means as, for instance, by the devices schematically illustrated in FIGURES 2 and 3.
  • the hot and dried chips are discharged from the tumbler on a conveyor belt 32, through a hopper 30 into a cavity filled with inert gas, for instance nitrogen at controlled humidity, not more than 70 mgr./m. contact with air being excluded.
  • This belt is made of a continuous strip of a large mesh fabric moved by two wheels 32 and 33 and running between two slits 34 and 35, so as to divide the space of the equipment in two zones 36 and 37 by suitable devices.
  • a cooled stream of nitrogen at controlled humidity, not more than 70 mgr./m. is forced from the space 36 to the space 37, thus crossing the layer formed by the polymer chips, which, at the end of its path, has a lower temperature that is fully determined by the conditions chosen for the operations.
  • the cooled polymer falls from the conveyor belt into a hopper 38 provided with a discharge wheel 39 which prevents the inert gas from escaping.
  • the chips are carried by a dry, inert gas through a pneumatic tube 40 into the feed tank 41 of FIG. 4.
  • the device schematically shown in FIG. 3, can be, for instance, another type of device for cooling the chips.
  • the dry and hot chips are discharged from the tumbler through a hopper 42 and the valve 43, onto a metallic plate 44 cooled by a cold water stream.
  • the polymer is caused to run over the entire length of such plate, by the vibration of vibrator 45 applied to the plate, while being covered by an atmosphere of inert gas, as for example nitrogen flowing from the tube 49.
  • the chips fall into the hopper 46 and are carried by a dry inert gas stream, through a pneumatic tube 40, into the feed tank 41 of FIG. 4.
  • the chips contained in the tumbler are allowed to cool in the latter by introducing dry nitrogen into the tumbler until atmospheric pressure is attained, followed by introduction of cold water into the jacket of the tumbler at a temperature between C. and 30 C. in substitution of hot water.
  • numher 41 represents a feed tank to which the chips are charged.
  • Said tank is a cylindrical container supplied with a discharge hopper 42 and a valve 43 through which the chips are fed to the melter 44.
  • the chips are charged into the feed tank by the known equipment and devices, thus they are charged through a hatchway 45, preferably pneumatically; that is, the chips are conveyed by a nitrogen stream, which enters through the said hatchway and flows out through a discharge mount 46 to be recycled.
  • the pipe 47, provided with the valve 48 is set to keep under pressure of nitrogen the whole equipment at the starting of the spinning and to discharge it at the end of the spinning.
  • the tank or silo 41 is provided with three thermometers, a-b-c, whose bulbs penetrate into the polymer.
  • the spinning head 44 which is of the type described for instance in the Patent No. 492,712 mentioned, the lower part of which has a substantially taper shape and forms the melting chamber.
  • the openings 50 and 51 are provided for the inert gas to circulate inside.
  • the taper wall of the melting chamber is heated by means of the jacket 52, and forms one of the heating surfaces.
  • the lower outlet of the melting chamber is closed by a nonheated grid to prevent solid chips of polymer from passing beneath said melting chamber.
  • the outlet of this chamber is connected to a pipe 53 which is suitably connected to one or more spinnerettes.
  • heating bodies 54 of any suitable form are placed inside the melting chamber, the surfaces of said bodies are to be kept at a relatively high temperature in order to heat the liquid polymer surrounding such heating bodies to the desired extent and to melt any-solid particles which may come in contact with said bodies.
  • the heating bodies are to be kept at a distance greater than the maximum size of the largest chips of polymer, and they should not prevent the polymer chips mixed with the liquid' from advancing, such chips being inclined to precipitate by gravity.
  • the type of spinning head of the melting chamber, the spinnerettes as well as the relative pumps and various connections used are not critical and since they are not a part of the invention, any type known can be used, for instance, the spinning head could be provided With'a melting tubular grid or any other type of melt spinning head known could be used.
  • Example 1 An amount of 2500 kg. of chips (made of small cylinders of resin of 2 mm. diameter and 3 mm. length) are dried in the tumbler dryer of FIG. 1, which has an internal diameter of 200. cm. and a length of 300 cm., at the temperature of C. by step-wise removal of the air and the humidity under a vacuum of 1.5 m. Hg.
  • the operation is carried out easily by slowly rotating the tumbler around an axis passing through a diagonal.
  • the polymer is conducted from the inert gas dryer into the silo set over the melter, as in FIG. 4, where, it feeds the melter by gravity.
  • the internal diameter of the silo is 150 cm. and the height 230 cm.
  • the silo is supplied with three thermometers a-b-c, the bulbs of which penetrate into the polymer; after the charge, they indicated the following temperatures respectively:
  • a number of cops, thus obtained at successive intervals of time and derived from fractions of the polymer which were successively melted during the course of the spinning operation, are wefted by means of a shuttle loom on a warp according to a picking called saglia.
  • the fabric so obtained was dyed with the following dyes:
  • the count regularity has been evaluated as follows:
  • the percentage of the yarn found out of count has been 12-13%.
  • thermometers a-b-c After charging the polymer in the silo, the following temperatures can be read on the thermometers a-b-c:
  • the spools of yarn drawn were wound up in the same periods and were woven under the equivalent conditions described in the previous experiment; then they were dyed in the same coloring baths mentioned before, and show a very slightly different absorption of dye which, however, is not easily detectable even by an experienced eye.
  • Example2 An amount of 2500 kg. of chips (made of small resin cylinders with 2 mm. diameter and 3 mm. length) are dried in a tumbler dryer at a temperature of C. by gradually removing the air and the humidity under a vacuum of 1.5 mm. Hg.
  • the operation is easily carried ,out by slowly rotating the tumbler about an axis passing through a diagonal.
  • the humidity that in the starting chips reached 8.5% is lowered to 0.075 throughout the mass of chips.
  • the tumbler is set to atmospheric pressure by introducing pure nitrogen containing amounts of H 0 not greater than 70 rnmgr/mm. of nitrogen.
  • thermometers a b-c After charging of polymer in the silo, the following temperatures can be read on the thermometers a b-c:
  • the spools of drawn yarn, wound up and dyed as in the Example 1, show a very slightly different dye absorption which, however, is not easily detectable even by the most experienced eye; whereas when repeating the same operations without previously cooling the chips the differences of absorption are very appreciable, considering as out of count the yarn portions whose count has wastes greater than :L3.6% in respect to the normal count; the percentage of the out of count yarn, when cooling the chips, is of 0.6%, whereas it rises to 12.5% when cooling is not carried out.
  • cooling is :ifected by contacting the chips with a stream of inert gas at controlled humidity during transfer.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
  • Artificial Filaments (AREA)
  • Finishing Walls (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
US352394A 1963-03-15 1964-03-16 Melt spinning process of polyamides Expired - Lifetime US3345445A (en)

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IT540263 1963-03-15

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US (1) US3345445A (da)
BE (1) BE645212A (da)
DE (1) DE1435677B1 (da)
GB (1) GB1019099A (da)
NL (2) NL6402668A (da)
NO (1) NO122604B (da)
SE (1) SE301690B (da)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4127635A (en) * 1974-04-09 1978-11-28 United States Gypsum Company Method for extruding thermoplastic polymers
US5279783A (en) * 1992-01-30 1994-01-18 United States Surgical Corporation Process for manufacture of polyamide monofilament suture
US5349044A (en) * 1992-01-30 1994-09-20 United States Surgical Corporation Polyamide monofilament suture manufactured from higher order polyamide
US5458838A (en) * 1992-03-11 1995-10-17 Kabushiki Kaisha Kobe Seiko Sho Heating and extruding method for bulk preform
CN108842197A (zh) * 2018-08-21 2018-11-20 林枫 一种聚酰胺纤维生产工艺
CN109023548A (zh) * 2018-08-21 2018-12-18 林枫 一种化纤纺丝干燥工艺

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4470880A (en) * 1982-06-18 1984-09-11 Allied Corporation Method for separating a liquid waste finish composition

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2295942A (en) * 1940-08-02 1942-09-15 Du Pont Manufacture of filaments
US3035303A (en) * 1958-11-14 1962-05-22 Ici Ltd Extrusion of organic thermoplastic polymeric materials
US3036335A (en) * 1959-06-11 1962-05-29 Nat Rubber Machinery Co Apparatus and method for extruding thermoplastic material
US3040005A (en) * 1959-01-21 1962-06-19 Du Pont Process for increasing the molecular weight of polyamides

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE834420C (de) * 1942-10-21 1952-03-20 Glanzstoff Ag Verfahren und Vorrichtung zum Verspinnen schmelzbarer Kunststoffe
GB839210A (en) * 1957-05-07 1960-06-29 British Celanese Improvements in or relating to spinning

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2295942A (en) * 1940-08-02 1942-09-15 Du Pont Manufacture of filaments
US3035303A (en) * 1958-11-14 1962-05-22 Ici Ltd Extrusion of organic thermoplastic polymeric materials
US3040005A (en) * 1959-01-21 1962-06-19 Du Pont Process for increasing the molecular weight of polyamides
US3036335A (en) * 1959-06-11 1962-05-29 Nat Rubber Machinery Co Apparatus and method for extruding thermoplastic material

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4127635A (en) * 1974-04-09 1978-11-28 United States Gypsum Company Method for extruding thermoplastic polymers
US5279783A (en) * 1992-01-30 1994-01-18 United States Surgical Corporation Process for manufacture of polyamide monofilament suture
US5349044A (en) * 1992-01-30 1994-09-20 United States Surgical Corporation Polyamide monofilament suture manufactured from higher order polyamide
US5405358A (en) * 1992-01-30 1995-04-11 United States Surgical Corporation Polyamide monofilament suture
US5540717A (en) * 1992-01-30 1996-07-30 U.S. Surgical Corporation Polyamide monofilament suture manufactured from higher order polyamide
US5458838A (en) * 1992-03-11 1995-10-17 Kabushiki Kaisha Kobe Seiko Sho Heating and extruding method for bulk preform
CN108842197A (zh) * 2018-08-21 2018-11-20 林枫 一种聚酰胺纤维生产工艺
CN109023548A (zh) * 2018-08-21 2018-12-18 林枫 一种化纤纺丝干燥工艺

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Publication number Publication date
DE1435677B1 (de) 1973-02-15
BE645212A (da) 1964-09-14
NL6402668A (da) 1964-09-16
SE301690B (da) 1968-06-17
NL129742C (da)
NO122604B (da) 1971-07-19
GB1019099A (en) 1966-02-02

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