US2698459A

US2698459A - Spinning or extruding apparatus

Info

Publication number: US2698459A
Application number: US232816A
Authority: US
Inventors: Pedlow John Watson; Charles D Vandenburgh
Original assignee: American Viscose Corp
Current assignee: Cummins Inc; Akzo Nobel UK PLC
Priority date: 1951-06-21
Filing date: 1951-06-21
Publication date: 1955-01-04
Anticipated expiration: 1972-01-04

Description

Jan. 4, 1955 .1. w. PEDLOW ET AL 2,698,459

SPINNING OR EXTRUDING APPARATUS Filed June 21, 1951 C I; I; 42 3/ r F5 5 JNVENTORS.

JOHN WATSON PEDLOW CHARLE6 o. VANDENBURGH I A:;ORNEY.

United States Patent Ofiice 2,698,459 Patented Jan. 4, 1955 SPINNING on EXTRUDING APPARATUS John Watson Pedlow, Media, Pa., and Charles D. Vandenburgh, Charlestown, Md., assignors to American Viscose Corporation, Wilmington, Del., a corporation of Delaware Application June 21, 1951, Serial No. 232,816

Claims. (Cl. 188) This invention relates to a method and apparatus for extruding or spinning films, filaments or other continuous solid products of small cross-section and particularly to the extrusion of small streams of a liquid filamentforn ing material. Although the invention is broadly applicable to processes involving extrusion of this character, the invention will be described in respect to embodiments particularly adapted to spin filaments of regenerated cellulose from viscose.

When spinning solutions, such as of viscose, cellulose acetate in acetone, etc., are forwarded to extrusion dies, such as spinnerets, it sometimes happens that gels or inadequately dispersed lumps are present. It has also been observed, when spinning viscose having a temperature which diifers substantially from the temperature of the spinning bath and particularly when the spinning bath is maintained at a temperature substantially in excess of that of the viscose solution, that the filaments produced from the outer streams discharged by the spinneret are of different denier than those produced from the inner apertures of the spinneret and that the behavior of these groups of filaments in succeeding treatments, such as stretching and dyeing, is different. Moreover, when the spinning is conducted in a bath maintained at a temperature considerably higher than the filament- It is an object of the present invention to provide a 7 method and apparatus for improving the uniformity of the spinning material and for providing a substantially uniform rate of flow of the material through all of the holes of the spinneret or extrusion plate. Another object is to conduct a film-forming material through a duct and to and through an extrusion plate or spinneret submerged within a fluid maintained at a temperature substantially different than that of the material without loss or gain of heat by the material. Another object is to accomplish the spinning of artificial filaments within a liqiud coagulating bath maintained at a temperature substantially hotter than the filament-forming material without causing decomposition of such material, formation of gaseous products therein, or other effects deleterious to the spinning of filaments that might otherwise occur as the result of the transfer of heat from the coagulating bath through the walls of the feed-duct and of the spinneret into the film-forming material passing therethrough. It is also an object to provide apparatus capable of spinning filaments at rapid spinning rates, i. e. above 150 .meters per minute, into high temperature spinning baths to obtain yarn of uniform high quality.

Fig. l is an elevation partly in section in one embodiment of the invention;

Fig. 2 is a cross-section of the spinneret used in the apparatus of Fig. 1',

dFig. 3 is a section of a modified spinneret installation; an

Fig. 4 is a plan view of a portion of the embodiment of Fig. 1.

The present invention comprises a method and apparatus for reducing or eliminating variations in viscosity or temperature or other property of a filament-forming material within a stream thereof by agitation thereof as it is being conducted to a spinneret or extrusion plate. It is particularly concerned with a system for continuously heating and homogenizing a stream of the filamentforming material to provide a uniformly elevated temperature therein with respect to the cross-section thereof. Preferably, as the conditioned or homogenized stream progresses to the plate or spinneret, it is protected from any material losses or gains in heat. In the embodiments to be described, the apparatus for obtaining the homogeneously heated stream of spinning material may be provided with means for efiiciently heat-insulating the duct system extending from the homogenizer to the spinneret and preferably also for insulating the lateral walls of the spinneret. In one specific embodiment, the stream is obtained in a uniformly heated and mixed condition by passing it through a feed-pipe or tube extending through a heated liquid bath and then through a mechanical mixer into the insulated duct system. In another embodiment, a uniformly heated stream is obtained without the necessity for mechanical mixing by passage of the stream through a high frequency dielectric heater.

The embodiment of the invention illustrated in Fig. 1 comprises (in the order in which they are connected together to conduct a filament-forming material) a gear pump 5, a filter unit 6, a coiled tube 7 supported within a container 8, a mixing vessel 9, a swivel joint 10, a tube 11 and a spinneret 12 positioned within a container 14 adapted to hold a coagulating liquid for the filamentforming material. The pump 5 and filter unit 6 are of conventional construction and function in the manner customary in conventional spinning equipment. The pump 5 is connected by pipe 4 with a supply (not shown) of a liquid filament-forming material, such as a viscose solution. The vessel 8 contains a liquid for changing or controlling the temperature of the material passing through the tube 7, which is preferably made of a heat conductive material, such as metal. The liquid is preferably maintained at a predetermined level by means, such as the outlet port 16. The temperature of the liquid supplied thereto may be controlled in any desired manner such as by pre-heating the liquid before it enters the vessel or by providing means within the vessel for heating the liquid, such as the manifold 17 which may be used to introduce steam or other heated gas into the liquid of the vessel 8.

The filament-forming material passes through the heatinterchange coil 7 into the mixing vessel 9. When heating a liquid by conduction, such as by heating a conduit therefor, the outermost layer of the liquid stream passing through the conduit is the first portion to be heated. The temperature of the stream is progressively less toward its center with the viscosity thereof being progressively greater toward the center in accordance with the reduction to temperature. There is a strong tendency, particularly with liquids having substantial viscosity, to maintain a state of viscous laminar flow in passing through ordinary ducts or pipes of circular cross-section. In order to avoid the necessity to provide an extremely long tube 7 for obtaining uniform temperature from the center 8 to the outer lamina of the stream therein, the mixing chamber 9 is provided for receiving the material discharged from the coil 7 and for thoroughly mixing the material immediately before it passes through the duct 19 to the joint 10, pipe 11 and extrusion device, such as the spinneret 12. In the chamber 9, the material is stirred by means, such as an agitator 20, supported within the vessel and mounted on a shaft 21 extending through the bottom of the vessel 9 and driven by any suitable means such as by the belt 22 shown in engagement with a pulley 23 on shaft 21.

The container 9 and the tube 19 are preferably formed of a material having a low heat transfer coefficient, but if a material having a high heat transfer coefficient, such as metal is used, it is coated or jacketed with a heat insulating material.

As shown in Fig. 1, the tube 11 is connected with the tube 19 in a swivel joint 10 (see Fig. 4) which comprises a fitting 24 held in clamped relationship between the legs as a heat transfer barrier.

. 3 1 of a'bifurcate member 25. Passageways 26, 27 of

members

24 and 25 respectively are contiguous and connect tubes 11 and 19 together as a continuous duct system. The bracket 25 is provided with a stop surface 28 which The tube 11 may be formed of a material a glass tube covered with outer tube wrapping, or coating. comprising polyethylene, a vinyl resin, a resin impregnated or. coated glass fabric or fibrous 11131811211, or

other material having high heat insulating properties.

To permit the use of conventional couplings for attach- I ing the spinneret 12 to the tube 11, the spinneret is provided as shown in Fig.2 with an inner sleeve 30 comprising a heat-insulating material such as polyethylene, a urea-formaldehyde type resin, a melamine-formaldehyde type resin, a vinyl resin, arubber-like composition such as vulcanized polychlorobutadiene or pressed or laminated textile fiber material coated or impregnated with a liquid impervious resin.

Fig. 3 illustrates the use of a spinneret '12 Without any internal sleeve such as sleeve 30 of Fig. 2. The material passing into the spinneret through the tube 13 is prevented from exchanging heat with the liquid coagulating medium in which the spinneret and the tube 13 are submerged by an insulating covering 31 for the tube 13 and by providing a special coupling .32 which has a hood .33 formed of insulating material which completely encloses the lateral walls 34 of the spinneret. A washer 35 of resilient material is he'ldbetween the inwardly extending end of the hood 33 and the tapered end wall of the spinneret to prevent the collection of sludge in the clearance region .37 extending between the outer surface of the spinneret and the inner surface of the hood. Su h clearance has utility A resilient washer 38 is provided between the flange 39 of the spinneret and the flanged end portion 40 of the tube 13. The coupling 32 is secured in threaded relationship to a coupling member 42-of insulating m terial to btain a sealed joint between the spinneret and the tube 13.

By emplo ing the nresent invention, materials used to form continuous solid products of small cross-section,

such s filaments. may be extruded :in a liquid condition 'into liquid co ulants and/or regenerants maintained at substantially different temperature than that of the material to be extruded without the obiectionable results that accrue "when a stream of fil n-forming material has concentric portions thereof difiering ;in viscosity and temper ture.

Whi e preferred embodiments of the invention have been shown and described; it is to be understood that chan es and variations may be made without departing from the snirit and scope of the invention as defined in the annended claims.

We claim:

1. A paratus for extruding a liquid filament-forming material c m rising a d ct system h ving a m in ssa eway: an e trusion member comprising a perforated portion enclosin one e d of the passageway through which m terial m vbe dischar ed from the svstem in small filanent-f mi s re ms: means associ ed with said system for nositive v forw rdi the material to the member; means s ci ted with the duct s stem for conditioning the mate ial com rising means for heating successive nor- .tions -of the material as they pass throu h a redetermined porti n frhe' svstern s aced .a substantial ortion of 'its len th from the member. and means for dis osing the material comprising'a duct system having a main passageway, an extrusion member comprising a perforated portion for enclosing one end of the passageway through which the material may be discharged from the system in small filament-forming streams, means associated with said system for positively forwarding the material to the member, means in heat-exchanging relation with a predetermined portion of thesystem spaced by a substantial portion of its length from the member, means disposed within the system in adjacent advanced relation with the heat-exchanging means for successively mixing said por-, tions of the material after being heated into a homogeneously heated condition, and means extending from said mixing means to the perforated member portion in circumferential relation with the passageway for insulating the intervening portion of the duct system against a substantial transfer of heat through the wall thereof.

3. Apparatus for extruding a liquid filament-forming material comprising a duct system having a main passageway, an extrusion member comprising a perforated portion enclosing one end of the passageway through which the material may be discharged from the system in small filament-forming streams; meansassociated with said system for positively forwarding the material into the member; a container having a level defining a height at which a liquid is normally maintained therein, said system comprising a portion contiguous with the member which is swingable into and out of-a region within said container below said level; means associated with the duct system for conditioning the material comprising means for heating successive portions of the material as .they pass through a stationary portion of the system, and means fordisposing the material of said successive portions in a homogeneously heated condition; and means extending from said conditioning means to the perforate member portion in circumferential relation with the passageway for insulating the intervening portions of the duct system against substantial transfer of heat through the wall thereof. I

4. Apparatus for extruding a filament-forming mate rial comprising a duct system having a main passageway;

an extrusion member comprising a perforated portion enclosing one end of the passageway and having an annular lateral wall constituting a portion of said duct system; means associated with said system for positively forwarding the material to the perforated portion of the member; means associated with the duct system for conditioning the material comprising means for heating successive portions of the material as they pass through a predetermined portion of the system spaced substantially along its length from the member, and means 'for disposing the material of such portions in homogeneously heated condition; and means extending from said conditioning means to the perforate member portion in circumferential relation with the passageway for insulating the intervening portions of the duct system including said lateral wall of the member against substantial transfer of heat through the wall thereof.

5. Apparatus as defined'in claim 4 wherein the insulating means comprises an internal sleeve extending in substantially complementary relation with the lateral wall' of the member. 7

6. Apparatus as defined in claim 4 wherein the insulatmg means comprises a coupling for attaching the member to a contiguous portion of the duct system, a portion of said coupling being substantially axially co-eXtensi-ve with the entire'lateral wall of the member.

7. Apparatus as defined in claim 6 comprising a resilient washer disposed between annular surfaces of thecoupling and the member in adjacent circumferential relation with the perforated portion of the member.

8. A method of spinning artificial filaments comprising forwarding a stream of liquid filament-forming material through a duct system terminating in a spinneret, -conditioning the material by changing the heat content of successive portions of the material as they pass through a fixed portion of the system and successively disposing the material of all of such portions in a homogeneous condition with respect to the heat content and viscosity there- 7 theheat content of successive portions of the material as' they pass through a fixed portion of the system, successively disposing the material of all such portions in a homogeneous condition with respect to the heat content and viscosity thereof, maintaining such homogeneously heated viscous condition as the material passes toward the apertures of the spinneret by substantially stopping the passage of heat through the walls of that portion of the duct system for conducting the homogeneously conditioned material including the lateral wall of the spinneret irrespective of the temperature of a medium which surrounds the spinneret and said latter-named portion 10 of the system.

10. A method of spinning artificial filaments comprising forwarding a stream of liquid filament-forming material through a duct system terminating in a spinneret, conditioning the material by heating successive portions of 1 it as they pass through a fixed portion of the system and successively mixing such portions to produce a homogeneous condition of the material with respect to the heat content and viscosity thereof, maintaining such homogeneously heated and viscous condition as the material passes toward the apertures of the spinneret by substantially stopping the passage of heat through the walls of the portion of the duct system for conducting the homogeneously conditioned material irrespective of the temperature of a medium disposed externally of the spinneret and such portion of the system.

References Cited in the file of this patent UNITED STATES PATENTS 2,064,915 Hubert et al Dec. 22, 1936 2,295,942 Fields Sept. 15, 1942 2,435,416 Thomson et a1 Feb. 3, 1948 2,514,189 Spencer et a1 July 4, 1950 2,586,970 McDermott Feb. 26, 1952