US3156950A - Spinnerets and methods of making them - Google Patents

Description

Nov. 17, 1964 T. WALTON, JR 3,156,950

SPINNERETS AND METHODS OF MAKING THEM Filed May 9, 1962 2 Sheets-Sheet l o o o o 1964 T. WALTON, JR 3,156,950

SPINNERETS AND METHODS OF MAKING THEM Filed May 9, 1962 2 Sheets-Sheet 2 United States Patent 3,156,950 SPINNERETS AND WTHUDS OF MAKING '5? EM Thomas Walton, In, Qolwiclr, Cherry Hill, N.J., assignor to Eohm 8r Haas (Company, lhiladelphia, Pa, a corporation of Delaware Filed May 9, 1%2, Ser. No. 1%,466 7 Claims. (Si. 18-45) The present invention is concerned with multi-hole spinnerets and methods of making them. It is particularly concerned with a novel and improved spinneret and an improved method for producing spinnerets of this type in an eificient and inexpensive manner.

It is known and quite common practice to produce spinnerets by drilling the holes in plates of suitable material and thickness such as of thin corrosion-resistant metals or of glass or ceramic plates of various thicknesses. It is also known to mount wires in a molten material such as glass or metal of different composition than the wire and subsequently subject the mounting to a material, such as an acid, which corrodes and eats out the wire While leaving the surrounding glass or metal mounting material. Both of these processes are of time-consuming and expensive character. Both of these methods are particularly expensive and laborious when it is desired to provide spinnerets having long bores which are of special advantage in particular types of spinning operations.

It is an object of the present invention to provide multihole spinnerets having capillary openings which may have any desired length of bore of uniform diameter. It is also an object of the present invention to provide a simple, rapid, eiilcient, and inexpensive method of producing a multi-hole spinneret regardless of the length of the orifices or holes therein.

It is also an object of the invention to provide improved spinnerets and methods of making them adapted to accommodate large numbers of holes and having great versatility in respect to spacing, length and diameter of orifice passage, and also as to the materials from which the spinne-ret is formed.

In the drawing which is illustrative of the present invention,

FIGURE 1 is a face view, greatly enlarged, of a portion of spinneret of the present invention,

FIGURE 2 is an enlargement of a portion URE 1,

FIGURE 3 is an enlargement of a portion of a similar face View of a modification,

FIGURE 4 is a longitudinal section of an assemblage of capillary tubes showing one stage of the method of manufacture,

FIGURE 5 is another longitudinal section similar to that of FIGURE 4 but showing a modification,

FIGURE 6 is a face view of a template, having bored or etched openings,

FIGURE 6a is a longitudinal section of the capillary tube assembly at one stage of the manufacture of template spinnerets,

FIGURE 7 is an end view of a capillary tube assembly using a woven template,

FIGURE 8 is an end view of a Water type capillary tube assembly,

FIGURE 9 is a modification of the wafer method of producing spinnerets showing two Wafer sections assembled together,

FIGURE 10 is a longitudinal section showing one way of mounting the spinneret of the present invention,

FIGURE 11 is a longitudinal section of a modified mounting system for the spinneret of the present invention, and

of FIG- FIGURE 12 illustrates another modification of a mounting arrangement.

In general the spinneret of the present invention comprises a plurality of adjacent capillary tubes parallel to one another, united by a cement disposed between the outer walls of the adjacent tubes, into an integral unit having the passages or channels of the tubes extending between and opening into terminal faces of the unit. The diameter of the passages may be from about 0.05 to 0.3 mm. and the space between the peripheries of adjacent openings of the orifices may be from about 0.038 to about 0.8 mm. or greater. The length of the capillary passage may vary widely. For most practical purposes, lengths of 0.75 to or more millimeters may be employed and preferred spinnerets have passages of a length from about 5 to 15 mm.

As shown in FIGURE 1, the spinneret comprises a plurality of individual tubes 2 having capillary passages or channels 3, the tubes being adhered together by any suitable cement 4.

FIGURE 2, having a greater enlargement, gives the construction in clearer detail.

The spacing between adjacent orifices or passages may be varied by using capillary tubes having greater or less wall thickness. Alternatively, as shown in FIGURE 3, solid rods 2:: may be interposed between the tubes 2. The rods 2a may be any suitable cross-sectional shape such as square, hexagonal, or circular (as shown) and may be of any suitable thickness or diameter. For example, they may be of 0.12 to 0.8 mm. in thickness or iameter. Instead of interposing rods, the tubes may be spaced by relying upon the use of extra cement 4 to hold the tubes apart the desired distance. The spacing may be controlled by the use of bored, etched, or woven templates 36 (FIGURES 5, 6 and 7) as will become apparent from the description hereinafter.

The spinnerets of the present invention may be made by assembling any desired number of tubes having capillary passages, which tubes may be formed of any material such as glass or metal within an outer sheath or jacket 5 (see FIGURE 4). The tubes may be of any length, such as from 5 to mm. or more. After assembling, the tubes are cemented together and the unitary body, having parallel passages therethrough, is then cut at intervals transversely with a suitable rotary knife or abrasive wheel to provide unitary spinneret bodies having any desired length of passage. The sheath may be of any cross-sectional contour, such as hexagonal, oval, or circular, as shown. The sheath may be of various thicknesses. For example, if of metal, it may range from 0.25 to 3.5 mm. thick, and if of plastic, glass, or ceramic material, about 1.25 to 6 mm. thick.

The bundle o5 tubes may number from a few, such as a half-dozen to a dozen, to hundreds or thousands (eg. 30,000 to 59,000), the overall width or diameter of the face of the resulting spinneret being from about an eighth of an inch to 3 inches or more. Using glass capillary tubes commercially available having an outer diameter of 0.4 mm. and an inside or passage diameter of 0.19 mm., a practical spinneret having 200 holes requires only a face diameter of 9.5 mm. Comparable compactness is obtained from stainless steel tubing, commonly employed for the making of hypodermic needles.

As shown in FIGURE 4 the bundle of tubes 2 are disposed parallel to one another and inserted with their closed ends 6 into the sheath 5. Either before or after insertion of the tubes 2 into the sheath 5 any suitable cement in liquid or powdered solid form may be introduced within the sheath 5 between the tubes. For example, the sheath 5 may be disposed on a plug: 7 which serves to close the end of the sheath during insertion of the tubes and cement. Then a liquid adhesive or cement may be introduced into the sheath above the plate after which the tubes are inserted. The insertion of the tubes 2 forces the cement upwardly until it reaches the top of, or overflows, the sheath 5. The cement, after removal of any excess from the outside of the sheath, can then be dried or cured by heating or allowed to cool, if it is simply in molten condition, to set and unite the several tubes into a unitary assembly. Thereafter, the assembly is cut at intervals transversely.

The invention is not limited to any particular cement as numerous thermoplastic or lthermosetting materials can be employed including phenoplasts, aminoplasts, polyepoxides, and vinyl resins. Simple thermoplastic materials may be used in molten condition and allowed to solidify. Polyvinyl chlorides, or plastisols containing them, with or without cross-linkers are quite useful. Thermosetting materials may include suitable catalysts to assist the curing and may be heated as desired. Cold setting adhesives may be employed. Molten salts, such as silver chloride, and oxides, such as magnesium oxide, are also useful.

If desired, the cement employed may be a powdered glass frit. After assembling the tubes within the sheath and disposing the frit between the tubes, the whole assemblage may then be subjected to heat to fuse the frit and cause it to cement the tubes together. When such a fusible hit is used with glass capillary tubes it should, of course, have a lower fusing temperature than that of the tubes so that the tubes are not distorted as a result of heating to fuse the frit.

The cement, which may be termed a mounting material or uniting medium, should be chosen so that it does not have so great a difference in heat expansion coefficient with respect to the material of the tubes (and when the sheath is to be permanently joined also, with re spect to the sheath) that the unitary spinneret does not retain its integrity under the conditions, especially the term perature of use.

The material of the spinneret, i.e., the tubes, cement, and sheath should be chosen to resist corrosion under the conditions of spinning which may often involve strongly acidic or alkaline spinning dopes or coagulating baths.

FIGURE shows a modification in which a foraminous plate or template 36 is disposed at each end of the sheath 5a. The tubes 2 are inserted into the holes 701 of the templates (which holes may be bored or etched) and the cementitious material is then supplied through suitable extra openings 7a in the top template in order to fill the space around the tubes 2 and between the templates.

FIGURE 5 also shows a modification in which the sheath is provided at intervals with circumferential rings or ribs 8. These rings are spaced apart by distances corresponding to the length of spinneret bore desired so that each spinneret is provided with at least one such ring to facilitate mounting as shown in FIGURE 11.

After the cement sets, the assemblage of FIGURE 4 or 5 is cut transversely at intervals to provide the spinneret units. The points of cutting of the embodiment of FIG- URE 5 may be chosen to place the rib 3 at one end of each unit or in the middle thereof. Again, the assemblage may be cut through the ribs 8 to provide a reinforcing ring at each end intsead of merely at one end or somewhere in the middle.

The cement employed may be one which adheres the tubes to the inside of the sheath 5 so that the sheath 5 forms an integral part of the assemblage. On the other hand a cement may be employed which does not adhere to the interior of the sheath so that after it is set the capillary tube assemblage may be withdrawn from Within the sheath. The use of a release agent coated upon the interior surface of the sheath may, in this instance, be helpful but it is unnecessary in most cases.

Generally, it is preferred to adhere the tubes having the capillary passages to the interior of a suitable sheath so that the latter provides a protective mounting support.

The capillary tubes 2 may be formed of metal, especially such corrosion-resistant metals as platinum, palladium, rhodium and alloys thereof, also nickel, Monel metal and stainless steel, or they may be formed of siliceous materials such as silica or glass. The sheath may be formed of metal, glass, crown of plastic or resinous material, such as polyvinyl chloride, polyethylene, nylon, and polyethylene glycol terephthalate.

After setting of the cement to unite the tubes together with or Without the sheath adhering thereto, the assemblage is cut transversely to remove the closed ends 6 and the sections of the assemblage are cut off at spaced intervals depending upon the length of bore desired in the spinneret.

When the capillary tubes are of metal, it is possible to cut the assemblage to provide capillary passages as short as 0.8 mm. However, with glass it is generally preferred to have a length of passage at least about 3 FIGURE 7 shows a woven template in which the spacing elements 7b may be the interwoven wire rods of a wire fabric.

FIGURE 8 shows a simple multi-hole spinneret formed by cementing a single row of parallel capillary tubes together to provide a thin wafer, which is cut transversely to provide spinnerets having passages or channels of any desired length.

A spinneret may be formed by assembling a plurality of such wafers, as in FIGURE 9, wherein two are cemented together. As in the other embodiments, the spacing between the spinneret holes or passages may be increased as desired by the insertion of solid rods 2a wherever desired.

FIGURE 10 shows one form of mounting in which a spinneret 9 having passages with a relatively great length is used. The spinneret unit 9 in this case is of cylindrical shape having a uniform outer diameter as would be obtained by cutting the assemblage of FIGURE 4 at intervals. A flexible plastic or rubber ring or ferrule it is slipped about the spinneret body 9 so that it grips the spinneret firmly. A fitting 11 is mounted on the feed pipe 12 for the material to be spun, making a threaded engagement therewith at 13. The fitting 11 is provided with a central bore or chamber receiving one end of the spinneret 9. The fitting 11 also has a tapered annular surface at 14 adapted to receive the annular sealing gasket 15 of rubber or other resilient material which is pressed against the ferrule 10.

A coupling unit 16 having a central bore or channel of suitable size to receive the spinneret unit 9 and having an inwardly facing tapered annular surface 17 has an internal threaded opening at 18 adapted to engage an outer threading 19 of the fitting 11. By tightening the coupling 16, the ferrule 15) is forced under pressure to engage and hold the spinneret 9 in fixed position.

In FIGURE 11 the flanged or ribbed type of spinneret unit 9a as obtained from the system shown in FIGURE 5 is mounted by insertion of one end within a pipe 12a adapted to supply the material to be spun to the spinneret.

A sealing gasket 20 is positioned between one end of the flange 8 and the end of the pipe 12a. A coupling unit 21 has an inwardly extending flange 22 adapted to surround the spinneret unit 9 and to engage the rib or flange 8. The ring 22 tightly engages the ring 8 when the couplingZl is screwed at 23 upon the pipe 12a.

FIGURE 12 shows a mounting assembly in which a thin plate or spinneret body 9b having orifices of short length is mounted. This short-bore spinneret plate 9b is held within a coupling unit 24 which has an inwardly extending rim or flange 25 which presses the plate against a sealing gasket 26, seated against the outer face of the mounting unit 27. The unit 27 is threadedly engaged upon the feed pipe 28 for the material to be spunand the coupling unit 24 also threadedly engages the mounting unit 27.

The spinnerets are useful for the spinning of a wide variety of materials. Such materials include viscose, cupramrnonium cellulose, casein solutions, solutions of vinyl resins including copolymers of vinyl chloride and vinyl acetate, as well as acrylonitrile polymers especially those containing at least 70% by weight of acrylonitrile, cellulose others such as cellulose acetate or cellulose acetate butyrate, cellulose others such as ethyl cellulose, and polyamide nylons. They are also useful for the melt-spinning of nylon, polyethylene glycol terephthalate, and vinyl resins such as the copolymers mentioned above. They are also useful in the dry spinning and wet spinning of any of the solutions mentioned hereinabove. The spinnerets of the present invention are also especially useful for the spinning of aqueous emulsion polymer dispersions whether the polymer is of polar or non-polar character. Thus, it may be employed for the spinning of rubber and synthetic rubber latices including those of butadienestyrene and butadiene-acrylonitrile polymers, polystyrene, polyethylene, and polypropylene, and the polar polymers disclosed in US. Patent 2,914,376.

The following examples illustrate the preparation of preferred embodiments by the method of the present invention.

Example 1 A stopper is inserted into one end of a length of a glass tube having an outside diameter of 1 cm. and a Wall thickness of 1 mm. A viscous cement of a mixture of sodium silico-fiuoride and finely-ground (200 mesh-Standard Tyler screen size) softer solder high density glass frit is poured into the glass tube. Then 260 precision glass capillary tubes (0.15 mm. inside diameter (I.D.) and 0.35 mm. outside diameter (G.D.)) are closed at both ends by quickly heating the ends in the flame of a laboratory gas burner and inserted endwise several at a time into the cement until they touch the inside Wall of the stopper and project about 2 to 3 mm. from the open end of the large tube. Excess cement is wiped from the outside of the large tube or sheath. The cement is allowed to harden for 24 hours. The assembly is then cut transversely at the desired spaced intervals with a carborundum wheel of soft variety which allows the particles to erode easily during cutting. During cutting, water is directed over the wheel to flush the particles and to prevent clogging of the passages of the capillary tubes. Then the cut faces are ground and polished while forcing Water or compressed gas through the capillary passages to prevent clogging by accumulation of debris. The f'mished spinneret thereby obtained can be used in one of the mountings of FIGURES to 12.

Example 2 One end of a soft glass sheath (4 mm. ID. and 1 cm. 0.1).) 9 cm. long is closed by heating in a gas flame and fusing the end. Then 200 (10 cm. long) commercially available precision-bore glass capillary tubes of the R-6 standard flint type (0.2 mm. 1.1).) are closed at each end by heating quickly to minimize the tendency to form a knob on the ends. These tubes are then fully inserted endwise into the larger glass sheath so that they protrude about 1 cm. beyond the open end of the sheath. The assembly is subjected to the action of a mechanical vibrator While the protruding ends are surrounded and covered with a finely-ground (260 mesh) lead solder sealing glass (such as of the type No. 7570, Corning Glass Works). After the interstitial spaces of the assembly are filled with the soft glass frit, additional frit is placed around the projecting ends of the capillary tubes and the whole unit is then placed in a furnace heated to 450560 C. and allowed to remain until the frit is sintered into a solid mass. Then the furnace temperature is allowed to drop to 400 C. for a short annealing period. It is then gradually cooled until the sintered assembly can be safely removed without cracking. The cutting, grinding, polishing, and mounting may then be carried out as in Example 1.

Example 3 (a) Spinnerets are made, by the general procedure of Example 1, using as a mold in some instances the same glass sheathing and in other instances a metal sheath of comparable size. In all cases, the capillary tubes used are of 0.1 mm. 1.1). and 0.3 mm. OD. and the cement used is a poly(vinyl chloride) (PVC) plastisol. The assembly is heated in an oven at ll85 C. until the plastisol fuses. After cooling, the fused assembly of the capillary tubes is readily removed from the sheath and can be used as such, but preferably it is placed in a larger mold and surrounded with additional plastisol and then heated to fuse the plastisol and thereby form a thick protectlve sheath of poly(vinyl chloride) about the tube assembly. This unit is then cut transversely, ground, polished and mounted as in Example 1.

(b) The procedure of part (a) is repeated using a plastisol to which a thermosetting monomer, such as ethylene glycol dimethacrylate is added.

(0) Part (a) is repeated replacing the plastisol with a resin-forming poly(vic-epoxide) such as the condensation product of epichlorohydrin and Bis-phenol-A.

(d) The procedure of part (a) is repeated substituting for the plastisol a resin-forming rm'xture of (1) an unsaturated polyester obtained from a mixture of glycerol, trimethylolethane, phthalic anhydride, and maleic anhydride, (2) styrene or methyl methacrylate, and (3) a freeradical initiator.

Example 4 Three woven stainless steel wire screen templates are clamped together one above the other with their holes in alignment (FIGURE 7). Then 225 capillary tubes are sealed at one end to form a knob larger than the screen openings. The other ends are inserted into the holes of the several screens and allowed to hang. These ends are then closed and knobs are formed on them. The templates are then released and the assembly is placed in a cylindrical mold (13 mm. ID.) with the templates positioned in spaced relationship so that one is at each end and the third is in the middle of the capillary tubes. A cement is introduced around the tubes in the mold. The cement is hardened and then the assembly is cut at spaced intervals transversely to produce the spinnerets which are then ground and polished as in Example 1.

Example 5 (a) A bundle of a plurality of glass tubes is heated and drawn out lengthwise to form the desired inside diameter capillary hole or channel in each of the several tubes. The tubes are fused together along their lines of contact. A cement is introduced into the interstitial spaces and hardened. Then the assembly is cut, ground and polished as in Example 1.

(6) Part (a) is modified by inserting the bundle of tubes into a larger tube or sheath of glass of the same composition before drawing so that the sheath, as well as the tubes inside it, are drawn and fused together simultaneously. The interstitial spaces are then filled with cement which is hardened. Then the usual cutting, grinding and polishing is eilected as in Example 1.

Example 6 7 Fifteen metal or glass capillary tubes (10 cm. length) .are laid side-by-side in parallel relationships in contact with each other on a strip of the pressure-sensitive adhesive layer of a heat-resistant adhesive tape (see FIGURE 8). A cement is disposed between the capillary tubes and the adhesive tape and then is applied to fill the corresponding grooves. After the cement is set, a unitary wafer having a single row of small diameter openings is obtained. The spacing between openings can be changed by inserting solid rods between the capillary tubes in the row (FIGURE 9).

' to form a spinneret.

7 The single row wafer may be cut, ground and polished Generally, however, a plurality of such wafers are cemented together before cutting, grinding and polishing to provide spinnerets having the desired number of rows of orifices.

Example 7 Wires of stainless steel or other metal having a low oxidation rate which are highly polished are inserted into slightly larger passages in capillary tubes of glass having higher coefficient of expansion than the glass, one wire being inserted into each glass tube. A plurality of these wire-core/glass tube units are associated in parallel relationship and in contact to form the desired configuration of openings. The wires are clamped under tension at each end of the assembly and the assembly is placed in a furnace where it is heated to the working point of the glass (e.g. 560 C. for soft lead glass to 1,220 C. for hard borosilicate glass). Each tube contracts on the wire and the tubes fuse together at their points of contact. The assembly is cooled slowly to the annealing temperature (e.g. 365 C. for soft solder glass to 525 C. for hard borosilicate glass). Excessively prolonged heating should be avoided to prevent oxidation of the wire. When the glass reaches the strain point temperature, the the wires are removed either (1) by a stretching action with constant tension which releases the metal from the capillary or (2) by continuation of the cooling until the wires shrink in diameter sufficiently below the inside diameter of the glass tubes to allow free removal. The assembly is then cemented, cut transversely, ground, and polished as in Example 1.

I claim:

1. A spinneret consisting of a plurality of contiguous rods disposed parallel to one another having terminal faces at their ends, at least some of said rods having capillary passages of uniform diameter of about 0.05 to about 0.3 mm., the passages extending between and opening into the terminal faces of the rods having capillary passages, and the rods being united into an integral unit by cementitious material disposed between the outer walls of the rods and filling the spaces between the rods.

2. A spinneret as defined in claim 1 in which the rods are cemented within an outer sheath.

3. A spinneret as defined in claim 1 in which the rods are cemented within an outer sheath provided with a rib projecting radially outwardly therefrom.

4. A spinneret as defined in claim 1 comprising rods disposed between the rods having capillary passages parallel thereto.

5. A spinneret as defined in claim 1 in which the rods are of glass.

6. A spinneret as defined in claim 1 in which the rods are of metal.

7. A method of making a spinneret which comprises placing a liquid cement in a mold which defines a cylindrical cavity, inserting a plurality of tubes lengthwise into said cylindrical cavity whereby the outer surfaces of said tubes are wetted by said cement, at least some of said tubes having a constant internal passage of about 0.05 to about 0.3 mm. in diameter throughout the length of the tubes with the ends sealed, setting the cement to form a unitary structure consisting of said tubes and the set cement disposed between the outer walls of the tubes and filling the spaces between the tubes, removing said unitary structure from said mold and cutting off sections of the structure by cutting it transversely at intervals spaced along its length.

References Cited in the file of this patent UNITED STATES PATENTS 2,354,931 Tolman Aug. 1, 1944 2,372,878 Binns et al. Apr. 3, 1945 2,798,020 Balz et al. July 2, 1957 2,798,252 Cummings July 9, 1957 2,799,598 Biefeld July 16, 1957 2,965,925 Dietzsch Dec. 27, 1960 FOREIGN PATENTS 431,096 France June 15, 1911 442,630 France June 24, 1911 30,306 Great Britain 1910 253,209 Great Britain June 14, 1926

Claims (1)

1. A SPINNERET CONSISTING OF A PLURALITY OF CONTIGUOUS RODS DISPOSED PARALLEL TO ONE ANOTHER HAVING TERMINAL FACES AT THEIR ENDS, AT LEAST SOME OF SAID RODS HAVING CAPILLARY PASSAGES OF UNIFORM DIAMETER OF ABOUT 0.05 TO ABOUT 0.3 MM., THE PASSAGES EXTENDING BETWEEN AND OPENING INTO THE TERMINAL FACES OF THE RODS HAVING CAPILLARY PASSAGES, AND THE RODS BEING UNITED INTO AN INTEGRAL UNIT BY CEMENTITIOUS MATERIAL DISPOSED BETWEEN THE OUTER WALLS OF THE RODS AND FILLING THE SPACES BETWEEN THE RODS.

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