WO2003104535A1

WO2003104535A1 - Spinning device

Info

Publication number: WO2003104535A1
Application number: PCT/IB2002/002932
Authority: WO
Inventors: Massimiliano Bert; Luca Codeluppi
Original assignee: Tecnofil Srl
Priority date: 2002-06-10
Filing date: 2002-06-10
Publication date: 2003-12-18
Also published as: AU2002368005A1

Abstract

A spinning device comprising a support body (30a) capable of withstanding an operational pressure differential between an input pressure and output pressure and having an entry side (34) for exposure to the input pressure, and an exit side (3602) opposite the entry side; at least one opening (303a) provided in the support body and extending from the entry side to the exit side; at least one plug means (31a) fitting into the at least one opening and having at least one passage extending through the plug means; the at least one opening of the support body and the plug means being adapted to provide an intermatching function for retaining and sealingly holding the plug means in the body when the entry side of the support body is under the impact to the input pressure.

Description

SPINNING DEVICE

Field of the Invention

The invention generally relates to the art of producing continuous filaments, or filament yarns, of synthetic or semi-synthetic polymer compositions by forcing a generally fluid polymer composition through a spinneret and recovering the filaments or yarns obtained in this manner. Specifically, the invention relates to a spinning device for use as a spinneret.

Prior Art

Filament production by spinning is, in essence, an extrusion technique and the specifics of the extrusion die depend upon various parameters, one of them being the way in which the polymer composition is brought into a fluid state, i.e. whether a melt spinning, solution spinning, or gel spinning process is involved. This, in turn, depends upon the type of polymer used. Accordingly, the specifics of the spinneret will be dictated by the spinning method, e.g. the temperature and pressure conditions required for commercial production of filaments from the a given polymer composition and the type of filament, or filament use, required.

Generally, however, extrusion dies or spinnerets used for filament production must be capable, on the one hand, to withstand the conditions of pressure, temperature as well as specific properties, e.g. acidity, of the fluidized polymer composition, and to be capable, on the other hand, of yielding the required number of filaments with the required filament properties, e.g. tex count and/or cross-sectional shape of the filaments, at the speed and with the reliability needed for commercial filament production.

OBJECTS AND BRIEF SUMMARY OF THE INVENTION

Adaptation of a spinneret for a given spinning method and the operating condi- tions required for such method is conventional and is not a primary goal of the present invention. Rather, the invention aims at generally avoiding a major deficiency of conventional spinnerets for virtually all types of spinning methods, i.e. the essentially immutable definition of the spinning orifices by the openings that extend through the body of the spinneret from an entry side to an exit side, generally in a direction transverse to the main plane of the spinneret body.

For example, when a given opening becomes blocked by an accidental solids particle in the fluid polymer composition, or becomes functionally impaired in any other manner, no simple means of repair of the spinneret is generally feasible. Also, neither the number of spinning orifices nor their dimensional or functional characteristics can be easily modified.

Accordingly, it is a main object of the invention to provide for a novel type of spinning device capable of replacing conventional spinnerets and suitable for any type of spinning technique - such as, for example, melt spinning, solution spinning in any type of solvent including acids, gel spinning, and any modification or combination of such methods - while avoiding the limitations of conventional spinnerets just men- tioned.

Specifically, the invention aims at providing a spinning device of the type just mentioned where damaged orifices can be easily repaired and/or modified by replacement. This aim and further advantages that will become apparent as this specification proceeds will be achieved according to the invention by a spinning device having:

(A) a support body, e.g. a plate-shaped structure, capable of withstanding the operational parameters of a given spinning method regarding resistance against temperature and characteristics of the processed polymer composition and, specifically, to the pressure differential between an input pressure and output pressure, i.e. a relatively higher pressure at the entry or upstream side of the spinning device (the side closer to the source of the fluid polymer composition, e.g. an extruder, pump or other pressure-generating source), typically in the range from about 10 to about 200 bar for melt spinning and about 1 to about

20 bar for solution spinning or gel spinning, and a lower pressure (e.g. ambient pressure or sub-atmospheric pressures including vacuum) at the downstream side. The entry side surface of the support body is exposed to the input pressure while the support body's exit side is opposite to the entry side; (B) at least one opening provided in the support body and extending from the entry side to the exit side; while a spinning device according to the invention may have just one opening, a preferred embodiment of the inventive spinning device will have a plurality or even a multiplicity of such openings, typically at least 4 and preferably at least about 40 such openings; an upper limit, e.g. 10*000 or more, of the number of openings is dictated by geometry, the size of the plug means explained below, and the size of the support body which may have a round (including circular) or polygonal shape with a diameter or side dimension in the typical range of from about 50 to about 1000 mm and a thickness in the typical range of from about 5 to about 100 mm depending upon the characteristics of the material from which the support body is made, e.g. a structural high-performance metal, such as steel, titanium, tungsten, molybdenum and alloys thereof; carbides; or ceramics; (C) a separate plug (also termed plug means) associated with each opening of the support body and releasably held therein. At least one plug has at least at least one passage extending therethrough. However, if the support body has more than one opening, some of the associated plugs may have no passages and serve merely for closing the associated opening of the support body. This may be of use, for example, if a specific array of the spinning orifices or a reduction of the number of spinning orifices for a given operation is required.

Also, any given plug may have more than just one passage. The exit end of each passage is shaped and dimensioned for serving as a spinning orifice. For example, it may have round (including circular) or polygonal shape of the regular or irregular type or be shaped in any other manner for achieving a required cross-sectional shape of the filaments to be produced by extrusion from the spinning device. Preferably, each plug will have rotational symmetry around its longitudinal axis, i.e. its central axis coinciding with or running essentially parallel to the axis through the plus's passage or passages, if any. Typically, the width of a plug may be in the range of about 2 to about 50 mm, preferably about 2 to about 20 mm.

The passage or passages, if any, extending through a plug may have a uniform diameter but, preferably, have a larger diameter at the upstream or entry end than at the downstream or exit end, which latter end serves as a spin- ning orifice. For example, the diameter or width of the passage at the exit end of a plug typically is in the range of from about 0.1 to about 2 mm while the diameter at the entry end is in the range of from about 2 to about 10 mm. Generally, the openings of the support body and the associated plugs are shaped so as to provide an intermatching function for retaining and sealingly holding the plug in the body when the entry side of the support body is under the impact of the input pressure. However, each plug may normally be removed from the support body for re- pair, maintenance or modification of a spinning device according to the invention.

DEFINITION OF TERMS AND PREFERRED EMBODIMENTS

The term "polymer composition" as used herein is intended to refer to any synthetic or semi-synthetic organic polymer composition capable of being processed for production of continuous filaments by spinning. It includes any composition containing at least one organic polymer of synthetic or semi- synthetic provenience which can be transformed into a fluid state and may be a homopolymer, copolymer, graft polymer, or any other type of macromolecule, or a mixture of such polymers, typically accompanied by conventional additives, such as dyes, stabilizers etc. of the type known for use in filament production by spinning.

The term "about" when used herein is indicated to include any reasonable deviation from the parameter given herein that will still give an operable embodiment, Typi- cally, the term "about" is intended to include a deviation by 30% from the value given. As mentioned above, a preferred body has a plurality of openings, ranging from at least 4 and preferably at least about 40 openings to lO'OOO openings or more, and the corresponding spinning device will have an equal number of plugs associated with the openings; the intermatching function of the openings of the support body, on the one hand, and the associated plugs, on the other, can be provided, at least in part, by the shape of the opening and/or by the shape of the associated plug.

While the openings of the support body that receive the associated plugs may be isomorphous, this is not a critical requirement, and an inventive spinning may have a support body with different types of openings, both with regard to differing size as well as with regard to differing shapes. Of course, the outer shapes, at least, of the associated plugs will have to be modified, or - alternatively - a compensating insert may be used between an opening of the support body and its associated plug. Shape and/or material of the insert, should maintain the intermatching function. Also, as mentioned briefly above, some of the plugs may have no passage at all and serve to block the associated opening of the support body.

The intermatching function of the opening in the support body and its associated plug can be achieved by inter-matching conical and/or intermatching cylindrical faces and/or intermatching shoulder portions provided by the internal shape openings and the outer shape of the associated plugs. Complementally or alternatively, interlocking devices such as matching threads, bayonet-type fitting and other known connecting devices may be used to supply or supplement the intermatching function.

It will be understood that the term "intermatching function" is intended to broadly encompass the functional inter-relation of the shape and size of the opening of the support body, on the one hand, and the shape and size of the plugs, on the other, which insure a sealing connection and prevention of accidental separation under the conditions of the spinning operation but does not normally prevent intended separation if needed. Annular sealing means may be used at the inner surface of the openings, the outer surface of the plugs, or as separate intermediate items made of a suitable material, such as a relatively soft material, such as a light metal or light metal alloy, in the shape of a ring or a tubular or conical sleeve.

According to a preferred embodiment the plugs consists, at least in part, of a ma- terial having a higher coefficient of thermal expansion than the material of the support body. Typically, the coefficient of thermal expansion of the plug material should be at least about 10% and preferably at least about 30% higher then the material of the support body. For example, if the plug is made of aluminum or an aluminum alloy while the support body is made of steel, the coefficient of thermal expansion of the plug is about twice the corresponding value of the support body.

According to a second embodiment the invention provides a method of producing a spun polymer by extrusion comprising the steps of: (I) providing a spinning device as described above comprising:

(A) a support body capable of withstanding an operational pressure differential between an input pressure and output pressure and having: an entry side surface for exposure to the input pressure, and an exit side opposite to the entry side;

(B) at least one opening provided in the support body and extending from the entry side to the exit side;

(C) at least one plug means fitting into the at least one opening and having at least one passage extending through the plug means; the support body and the plug means being adapted (or: matched) to provide an intermatching function for retaining and sealingly holding the plug means in the body when the entry side of the support body is under the impact of the input pressure;

(II) extruding a polymer composition through the spinning device and

(III) recovering a plurality of filaments of the polymer composition. It will be noted that the details of performing steps (II) and (ITI) are well known in the art of producing filaments by extrusion so that no detailed explanation is required.

According to a further embodiment, the invention provides, e.g. as a separate commercial item, a plug means for use in a spinning device according to the invention as described above having, or not having, at least one passage extending in a substan- tially axial direction, the plug having an external shape with a portion, at least, shaped in rotational symmetiy, and wherein, the passage has an end capable of operating as a spinning orifice.

Preferably, a portion, at least, of the plug consists of a material selected from structural high-performance metals, e.g. steel, titanium, tungsten, molybdenum and al- loys thereof; carbides; ceramics; glass; synthetic mineral materials, e.g. ruby or sapphire; temperature-resistant synthetic polymers, e.g. commercially available polyimides or poly hetero-hetero ketones; and graphite.

According to yet another embodiment, the invention provides a spinning system or plant comprising a source of a polymer composition, a spinning device as disclosed above for use as a spinneret typically provided in a housing connected with the source of the fluid polymer composition; a pump, e.g. an extruder or solution pump for forcing the fluid polymer composition through the spinneret; means for allowing solidification of the fluid polymer composition after having passed the spinneret and for forming filaments of the polymer composition; and means for recovering the filaments. BRIEF DISCUSSION OF THE DRAWINGS

The invention will now be discussed in more detail with reference to the enclosed drawings in which: Figure 1 is a diagrammatic sectional view of a broken-away portion of a support body having an opening and an associated plug according to the invention illustrating an example of the concept of an inter-matching relation between opening an associated plug; Figure 2 is another diagrammatic sectional view similar to Fig. 1 showing a modification of the intermatching relation between opening and plug according to the invention;

Figure 3a is another diagrammatic sectional view similar to Figs. 1 and 2 combining differing types of the intermatching relation between opening and plug according to the invention; Figure 3b is a semi-diagrammatic sectional view with an intermatching arrangement of body and plug similar to Fig. 3 a but including a less diagrammatic illustration of the shape of the passage that extends through the plug; Figure 4 is a modification of the plug illustrated in Fig. 1 with two essentially parallel passages provided in one and the same plug instead of just one passage or no passage;

Figure 5 is a diagrammatic sectional view illustrating various dimensional parameters of essential components of the invention; and Figure 6 is diagrammatic view of a spinning device according to the invention arranged in a spinning chamber.

DETAILED DISCUSSION OF THE DRAWINGS

Fig. 1 shows a partial sectional view of a support body 10 having an upper, up- stream, or entry side 101, a lower, downstream or exit side 102, and an opening 103 extending in a generally frustro-conical manner from the entry side to the exit side of support body 10.

A plug 11 with an intermatching frustroconical shape is inserted into support body 10 and has a passage 113 that extend from the upper or entry side of plug 11 to its exit side 112. In reality, no interspace between body 10 and plug 11 exists but is shown in this and the other figures merely for simplicity of the illustration. By the same token, passage 113 would not normally have a uniform tubular shape but have its lower end narrowed down to form a spinning orifice.

Fig. 2 corresponds essentially with Fig. 1 by showing a support body 20 with an opening 203 having a tubular upper portion extending downward from upper face 201, a central shoulder portion, and another tubular portion ending in lower face 202. Plug 21 with its passage 213 has an outer shape for inter-matching with opening 203. Fig. 3 a corresponds essentially with Figs. 1 and 2 by comprising support 20 having an opening 303 for inter-matching with plug 31 but combining a frustro-conical section extending downwards from upper face 301 with a central shoulder and a lower tubular portion opening into lower face 302.

Fig. 3b is a semi-diagrammatic rendering of a structure essentially as illustrated in Fig. 3 a but indicating an annular sealing member 35 inserted between opening 303 a of body 30a and plug 31a. The passage extending through plug 3 la is shown to have a wider conical entry portion 34 at the upper or entry end, and a spinning orifice having a substantially smaller diameter at the lower or exit end.

Fig.4 corresponds essentially with Fig. 1 except that plug 41 is provided with two passages 413,414.

Fig. 5 is shown to indicate typical dimensional parameters as follows: A indicates the thickness parameter of a support body 10 ...40 and preferably is within the range of from about 15 - 35 mm with a typical thickness of 21 mm. B is the diameter of an opening 103...403 at the upper or entry side 101...401 of the support body and preferably is in the range of from about 9 - 14 mm with a typical diameter of about 11 mm.

C is the diameter of opening 103...403 at the lower or exit side 102...402 and preferably is in the range of from about 8 - 12 mm with a typical value of about 9 mm. D is the widest diameter of passage 113...413 of a plug 11...41 at the upper or entry side 111...411 and preferably is in the range of from about 4 - 10 mm with a typical value of about 5 mm.

Dl is the diameter of passage 113...413 in its central portion between upper side 111....411 of plug 11...41 and preferably is in the range of from about 2 -5 mm with a typical value of about 3 mm.

D2 is the diameter of passage 113...413 at the lower or exit side 112...412 of plug 11...41 and preferably is in the range of from about 0.3 to about 2 mm with a typical value of about 1.3 mm. Fig. 6 is a diagrammatic sectional view of the bottom part of a spinning chamber

5 with an inserted spinning device according to the invention formed by a plate-shaped support body 50 and differing types of inter-matching plugs 51,54 with a single passage per plug, plugs 53 with no passage to provide for blockage, and plugs 55 with more than one passage per plug. As will be readily understood by those experienced in the art, selection of materials for use in a support body and a plug according to the invention will depend substantially from the process parameters of the spinning process in which a spinning device according to the invention is used. Generally, those materials known to be suitable for conventional spinnerets for a given spinning process will also be suitable for a spin- ning device according to the invention. The same materials, or differing materials, can be used for the support body as well as for the plugs.

Further, with reference to the diagrammatic nature of the figures it will be apparent to those experienced in the art of spinning continuous synthetic filaments that the specifics of the spinning channels and spinning orifices will also depend primarily upon the nature of the fluid polymer composition, its viscosity including structural viscosity, chemical properties, and temperature, and - again - shapes of spinning channels and spinning orifices known to be suitable for conventional spinnerets will be suitable for spinning devices according to the invention with the characteristic difference that spinning channels and spinning orifices are not an integral part of the support body but are incorporated in the inter-matching plugs that can be inserted and withdrawn for maintenance, replacement, or adaptation as needed or desired in view of requirements of the spinning process.

Claims

CLAΓMS

1. A spinning device comprising: a support body (10...50) capable of withstanding an operational pressure differential between an input pressure and output pressure and having: an entry side (101...401) for exposure to said input pressure, and an exit side (102...402) opposite said entry side; at least one opening (103...403) provided in said support body and extending from said entry side to said exit side; at least one plug means (11...41) fitting into said at least one opening and having at least one passage (113...413) extending through said plug means; said at least one opening of said support body and said plug means being adapted to provide an intermatching function for retaining and sealingly holding said plug means in said body when said entry side of said support body is under the impact of said input pressure.

2. The spinning device of claim 1 wherein said support body (10...50) has at least 4 and preferably at least about 40 openings (103...403) and an equal number of plug means (11...41) associated with said openings, said intermatching function being provided, at least in part, by the shape of said opening and/or by the shape of said associated plug means.

3. The spinning device of claim 2 including plug means (53) designed to block passage through the associated openings provided in said support body (50).

4. The spinning device of claim 1 wherein said at least one passage (113...413) of said at least one plug means (11...41) extends from an entry side (111...411) of said plug means to an exit side (112...412) thereof, and wherein said passage at its exit side has a smaller diameter than at its entry side for serving as a spinning orifice.

5. The spinning device of any of claims 1 - 4 wherein both said at least one opening (103...403) in said support body (10...40) as well as said at least one plug means (11...41) have inter-matching conical and/or intermatching cylindrical faces and/or intermatching shoulder portions to contribute, at least in part, to said intermatching fύnc- tion.

6. The spinning device of any of claims 1 - 5 wherein an annular sealing means (35) is provided between said opening (303a) and said plug means (31a) , e.g. a ring or a tubu- lar or conical sleeve.

7. The spinning device of any of claims 1 - 6 wherein said plug means (11...41) consists, at least in part, of a material having a higher coefficient of thermal expansion than the material of said support body.

8. The spinning device of any of claims 1 - 7 wherein at least some of the openings (103...403) of said support body (10...40) and said associated plug means have differing shapes.

9. A method of producing a spun polymer by extrusion comprising the steps of: (I) providing a spinning device comprising: a support body (10...50) capable of withstanding an operational pressure differential between an input pressure and output pressure and having: an entry side (101...401) for exposure to said input pressure, and an exit side (102...402) opposite said entry side; at least one opening (103...403) provided in said support body and extending from said entry side to said exit side; at least one plug means (11...41) fitting into said at least one opening and having at least one passage (113...413) extending through said plug means; said at least one opening of said support body and said plug means being adapted to provide an intermatching function for retaining and sealingly holding said plug means in said body when said entry side of said support body is under the impact of said input pressure; (II) extruding a polymer composition through said spinning device; and (III) recovering a plurality of filaments of said polymer composition.

10. A plug means for use in a spinning device as claimed in any of claims 1 - 8, having, or not having, at least one passage extending in a substantially axial direction, said plug means having an external shape with a portion, at least, shaped in rotational symmetry, and wherein said passage has an end capable of operating as a spinning orifice.

11. The plug of claim 10 wherein a portion, at least, of said plug means consists of a material selected from structural high-performance metals, e.g. steel, titanium, tungsten, molybdenum and alloys thereof; carbides; ceramics; glass; synthetic mineral materials, e.g. ruby or sapphire; temperature-resistant synthetic polymers, e.g. polyimides or poly hetero-hetero ketones; and graphite.

12. A spinning system comprising: a source of a fluid polymer composition; a spinneret; a pump means for forcing said fluid polymer composition through said spinneret; a means for allowing solidification of said fluid polymer composition after having passed said spinneret and for forming filaments of said polymer composition; and a means for recovering said filaments; wherein said spinneret is a spinning device as claimed in any of claims 1 - 9.