ASSEMBLY AND METHOD FOR INJECTING A FLUID INTO MOLTEN POLYMERIC MATERIALS

Abstract

Polymeric Materials An injector (14) for injecting liquid formulation into molten polymer includes a conduit (117) having regions (44, 46) which are secured within a wall of an extruder (19). Conduit (117) includes an annular collar (120) having an upwardly facing annular surface (122) which is arranged to bear against part of a sleeve nut (124). Conduit (117) is arranged within a port (125) which includes a screw-threaded wall (126). The sleeve nut (124) includes a cylindrical body (146) having an inwardly facing cylindrical wall which is arranged to define a cylindrical air gap (148) between itself and an outer wall (147) of conduit (117). Region (150) of the sleeve nut is screw-threadedly engaged in wall (126) of the extruder. In use, cool compressed air is introduced into the assembly in the direction of arrow (170) and it flows through the assembly to cool it.

Claims

1. An assembly comprising: (i) a containing means for molten polymer; (ii) apparatus for injecting a fluid formulation into molten polymer contained in the containing means, wherein said apparatus is secured relative to the containing means; (iii) wherein said apparatus includes an injection device for injecting fluid formulation into molten polymer contained in the containing means; (iv) wherein said injection device comprises a conduit arranged to deliver fluid formulation into molten polymer in the containing means and a cooling fluid passageway associated with the conduit, said cooling fluid passageway being arranged to contain a cooling fluid which is arranged, in use, to cool the conduit and/or a fluid formulation present therewithin.

2. An assembly according to claim 1, wherein said containing means includes a wall (A) which defines a region for containing molten polymer, wherein said conduit of said injection device extends within the wall (A), wherein said containing means is part of a melt-processing apparatus and wherein said conduit extends from a first side of wall (A) to a second side of wall (A), wherein said second side defines a passageway in which polymer is disposed and/or flows in use, wherein said conduit includes an opening via which fluid formulation is injected, in use, into molten polymer in the containing means, wherein said opening has a mouth which opens directly into a region in said containing means in which molten polymer flows and/or is positioned in use.

3. (canceled)

4. An assembly according to claim 3, wherein said opening in said conduit is aligned with said second side of wall (A) and said opening preferably has a cross-sectional area at its narrowest point in the range 12 mm.sup.2 to 200 mm.sup.2.

5. An assembly according to claim 3, wherein said conduit includes an outer face which is at an extremity of the conduit and wherein said opening via which fluid formulation is injected, in use, into molten polymer extends through the outer face, wherein at least part of said outer face is contiguous with second side of wall (A).

6. An assembly according to claim 3, wherein said conduit includes an outer face which is at an extremity of the conduit and wherein said opening via which fluid formulation is injected, in use, into molten polymer extends through the outer face, wherein substantially no step is defined between the outer face of the conduit and the immediately surrounding area defined by the second side of wall (A).

7. An assembly according to claim 3, wherein said conduit includes an outer face which is at an extremity of the conduit and wherein said opening via which fluid formulation is injected, in use, into molten polymer extends through the outer face, wherein at an end of said conduit which includes an outer face, the conduit defines a first cylindrical region which engages a corresponding opening in a wall (A) which defines a region of said containing means for containing molten polymer; wherein an end of the conduit which includes an outer face thereof is seated upon a corresponding socket defined in the wall (A), wherein the socket includes an opening adjacent a second side of wall (A) and/or which opening opens into the passageway in which polymer flows in use; wherein at said end of said conduit which includes said outer face, the conduit includes said first cylindrical region and, upstream thereof, a second cylindrical region, wherein a step is arranged between the first and second cylindrical regions; and wherein, optionally, the first and second cylindrical regions are seated upon walls of said socket defined in the wall (A).

8. (canceled)

9. An assembly according to claim 1, wherein said conduit is not arranged to be directly screwed into a wall (A) of said containing means, wherein wall (A) defines a region of said containing means for containing molten polymer.

10. An assembly according to claim 1, wherein said containing means includes a wall (A) which includes a first side and a second side, where said second side defines a passageway in which polymer is disposed and/or flows, in use, wherein said cooling fluid passageway is arranged, at least in part, within wall (A), and extends between said first side and second side of wall (A), wherein said cooling fluid passageway extends from a first position which is spaced from said first side of wall (A) to a second position which is within wall (A).

11. An assembly according to claim 1, wherein one wall W1 of the said cooling fluid passageway is defined, at least in part, by said conduit arranged to deliver fluid formulation into molten polymer, wherein wall W1 defines an internal wall of the cooling fluid passageway.

12. An assembly according to claim 11, wherein said conduit includes a wall having a first surface which is an internal surface of the conduit and is arranged to contact fluid formulation as it passes through the conduit prior to injection of the fluid formulation into molten polymer and said conduit includes a second surface which is an external surface of the conduit and/or faces outwardly and does not contact the fluid formulation as it passes through the conduit, wherein the arrangement is such that cooling fluid in the cooling fluid passageway in use directly contacts said second surface of said wall of said conduit.

13. An assembly according to claim 12, wherein said second surface of said wall of said conduit includes a series of projections which are elongate and extend in the direction of flow of cooling fluid through the cooling fluid passageway, wherein the projections define a series of flow channels.

14. An assembly according to claim 12, wherein a second wall W2 of the cooling fluid passageway extends around the conduit and is arranged to contact cooling fluid in use, wherein wall W2 is part of a securement device by means of which the conduit of said injection device is secured in position.

15. An assembly according to claim 14, wherein said wall W2 is movable between an operative position in which it is secured within wall (A) and defines part of said cooling fluid passageway around the conduit and a second inoperative position wherein it is withdrawn from the operative position.

16. An assembly according to claim 14, wherein said securement device comprises a screw-threaded region which is arranged to screw-threadedly engage the containing means.

17. An assembly according to claim 14, wherein the securement device includes an inlet for passage of cooling fluid into said cooling fluid passageway and an outlet for passage of cooling fluid out of the cooling fluid passageway.

18. An assembly according to claim 14, wherein said apparatus for injecting a fluid formulation comprises said conduit and said securement device, wherein said conduit defines wall W1 of said passageway and said securement device defines wall W2 of said passageway, wherein preferably said passageway is solely defined by the conduit and said securement device and no other component of the apparatus for injecting.

19. An assembly according to claim 1, wherein the assembly includes a pipe which is operatively connected to said cooling fluid passageway and said pipe is connected to a source of cooling fluid; and said containing means contains molten polymer; and/or wherein said apparatus includes a receptacle containing a fluid formulation for injection into molten polymer via said injection device; and/or wherein said containing means is an extruder and downstream thereof is a spinning means for spinning molten polymer which has been contacted with fluid formulation.

20. (canceled)

21. (canceled)

22. An assembly according to claim 1, wherein said fluid formulation delivered in the method has a viscosity of at least 5000 cP and less than 250,000 cP, includes an additive which comprises one or more colourants comprising pigments or dyes and includes 15 to 80 wt % of vehicle and 20 to 85 wt % of additives.

23. A method of injecting a fluid formulation into molten polymer, the method comprising: (i) selecting an assembly according to claim 1, (ii) with molten polymer arranged in said containing means and with cooling fluid arranged in said cooling fluid passageway, operating said injection device to deliver fluid formulation into the molten polymer; wherein the method comprises causing cooling fluid to flow continuously in said cooling fluid passageway during the entirety of the time said injection device is delivering fluid formulation into the molten polymer.

24. (canceled)

25. (canceled)

26. An assembly comprising: (i) a containing means for molten polymer; (ii) apparatus for injecting a fluid formulation into molten polymer contained in the containing means, wherein said apparatus is secured relative to the containing means; (iii) wherein said apparatus includes an injection device for injecting fluid formulation into molten polymer contained in the containing means; (iv) wherein said injection device comprises a conduit arranged to deliver fluid formulation into molten polymer in the containing means and a cooling fluid passageway associated with the conduit, said cooling fluid passageway being arranged to contain a cooling fluid which is arranged, in use, to cool the conduit and/or a fluid formulation present therewithin; wherein one wall W1 of the said cooling fluid passageway is defined, at least in part, by said conduit arranged to deliver fluid formulation into molten polymer, wherein wall W1 defines an internal wall of the cooling fluid passageway; wherein said conduit includes a wall having a first surface which is an internal surface of the conduit and is arranged to contact fluid formulation as it passes through the conduit prior to injection of the fluid formulation into molten polymer and said conduit includes a second surface which is an external surface of the conduit and/or faces outwardly and does not contact the fluid formulation as it passes through the conduit, wherein the arrangement is such that cooling fluid in the cooling fluid passageway in use directly contacts said second surface of said wall of said conduit; wherein said second surface of said wall of said conduit includes a series of projections which are elongate and extend in the direction of flow of cooling fluid through the cooling fluid passageway, wherein the projections define a series of elongate flow channels.

Description

[0071] Specific embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

[0072] FIG. 1 is a schematic representation of apparatus for injecting a liquid formulation into molten polymer;

[0073] FIG. 2 is a cross-section through an injector;

[0074] FIG. 3 is a schematic representation of a conduit of an injector of a known apparatus engaged in a wall of an extruder;

[0075] FIGS. 4a and 4b are schematic representations of the conduit of the injector illustrating how the injector becomes blocked;

[0076] FIG. 5a is a schematic representation of an assembly including a modified conduit of an injector, in accordance with a preferred of embodiment of the invention, engaged in a wall of an extruder;

[0077] FIG. 5b is a schematic representation of a wall of the extruder prior to engagement with the assembly of FIG. 5a;

[0078] FIG. 6a is a perspective view of a modified assembly for engagement to a wall of an extruder (but excluding a movable pin for opening/closing an outlet of a conduit of the assembly);

[0079] FIG. 6b is a schematic cross-section through the assembly of FIG. 6a (but including the movable pin);

[0080] FIG. 6c is a cross-section along line VIc-VIc of FIG. 6b; and

[0081] FIG. 6d is an isometric view of the modified assembly (including movable pin).

[0082] In the figures, the same or similar parts are annotated with the same or similar reference numerals.

[0083] The following material is referred to hereinafter:

[0084] Formulation A1a proprietary liquid formulation including vehicle and a red dye.

[0085] As described above with reference to FIGS. 1 and 2, injector 14 is arranged to control passage of liquid formulation, via conduit 17 and outlet 21, into pressurized molten polymer stream 18. As shown in FIG. 3, conduit 17 includes outwardly facing, screw-threaded region 23 adjacent outlet 21 via which it can be releasably screw-engaged within a screw-threaded opening defined in metal wall 42 of extruder 19. Downstream of region 23, conduit 17 tapers inwardly to define a frusto-conical region 44 and, downstream thereof, it defines a cylindrical-region 46 in which outlet 21 is defined. Outlet 21 opens into passageway 48 which contains polymer steam 18. The regions 44, 46 are shaped to correspond to a conical seat defined in wall 42 of extruder 19 so the conduit can be tightened down onto the conical seat to prevent leakage of polymer from the extruder. In use, liquid formulation passes within passageway 50 defined in conduit 17 in the direction of arrow 52 towards outlet 21 from which it is injected into the polymer stream 18. A pin (not shown but analogous to pin 28 of FIG. 2) is movable in conduit 17 to close/open outlet 21. The liquid formulation may be injected at pressures which can be in the range 50-200 bar or more.

[0086] It is found that, in use, metal wall 42 may be at a temperature of up to about 300 C. by conduction of heat from molten polymer stream 18. In turn, tests have shown that conduit 17 can become heated to substantially the same temperature as the polymer stream. Some liquid formulations are found to be affected by this heating, notably Formulation A1, as described in Example 1 below.

EXAMPLE 1

[0087] A test-rig (not shown) comprises a heated block in which conduit 17 of an injector is screw-engaged in substantially the same manner as that described above with reference to FIG. 3. The temperature of the block can be adjusted, as can the dosing rate of liquid formulation passing through the conduit. In addition, dosing can be stopped for measured periods and restarted, to simulate practical situations.

[0088] Liquid formulation A1 was assessed using the test-rig at a relevant dosing rate of 2.92 grams per minute (gpm) (this being equivalent to the lowest likely addition rate in practice) over a range of temperatures. Results of observations are provided in the table below.

TABLE-US-00001 Temp. ( C.) Observation 150 Colourant a very soft paste in the test rig at the specified temperature. No fuming. No discolouration. No blocking. 175 Colourant a very soft paste in the test rig at the specified temperature. No fuming. No discolouration. No blocking. 200 Colourant appeared a slightly thicker paste in the test rig at the specified temperature. No fuming. No discolouration. No blocking. 225 Colourant caused a blockage on initial opening. Toggling injector pin freed blockage and dosing acceptable for remaining 10 minutes. Colourant a thicker paste at the specified temperature. No fuming. Slight discolouration (darker). 250 Colourant caused a blockage on initial opening; which was freed after toggling injector pin. After 10 minutes there was a slight pressure rise indicating some blocking occurring. Colourant thicker and darker in colour. No fuming. 275 Colour caused a blockage on initial opening. Toggling injector pin freed blockage for a short time, but after 1 minute there was complete blockage. Fuming present. Very thick paste and dark in colour.

[0089] Thus, it should be appreciated from the above that the formulation described can, disadvantageously, cause blockages in the injector in certain circumstances, for example as it becomes heated to higher temperatures.

[0090] In a series of experiments, the reasons why the injector becomes blocked were investigated. As illustrated in FIG. 4a, it was found that, initially, blocking by solid material (illustrated by reference numeral 33), originated on a ledge 31 which defines a seat for valve pin 28. Subsequently, there was a more extensive build-up of solid material resulting in complete blocking of the injector as illustrated by reference numeral 33 in FIG. 4b. Subsequently described embodiments were developed to address the problem of blocking.

[0091] A first embodiment of the invention is shown in FIGS. 5a and 5b. Referring to the figures, conduit 117 is similar to conduit 17 of FIG. 3 in that it includes frusto-conical region 44 and cylindrical region 46 which are shaped to correspond to a conical seat defined in wall 42 of extruder 19. However, conduit 117 does not itself include a screw-thread region, for example corresponding to region 23 in FIG. 3.

[0092] The conduit 117 includes an annular collar 120 having an upwardly facing (as shown in FIG. 5a) annular surface 122 which is arranged to bear against part of a sleeve nut 124 in use.

[0093] The conduit 117 is arranged within a port 125. An opening of port 125 which receives an assembly comprising conduit 117 and sleeve nut 124, is of a wider diameter compared to the diameter of the equivalent port in the FIG. 3 embodiment.

[0094] The port 125 includes a wall 126 which is screw-threaded, defining a first cylindrical portion; a wall 128 defining a frusto-conical portion; and a wall 130 defining a second cylindrical portion. The sleeve nut 124 includes a head 140, a lower annular surface 142 of which is arranged to seat upon annular surface 122 of collar 120 of conduit 117. The sleeve nut 124 includes a cylindrical body 146 having an inwardly facing cylindrical wall which is arranged to define a cylindrical air gap 148 between itself and an outer wall 147 of conduit 117. Towards its distal end, in region 150, outer cylindrical wall 151 of the sleeve nut is screw-threaded and arranged to engage screw-threaded wall 126. Sleeve nut 124 also includes an air inlet 160 adjacent head 140 and an air outlet 162. The outlet 162 is offset relative to inlet 160 at approximately 180 about the periphery of cylindrical wall 151 and is axially spaced so outlet 162 extends through screw-threaded region 150 and, in use, is positioned adjacent an outer wall of extruder 19.

[0095] Dimensions of elements of assembly of the FIGS. 5a and 5b are as follows: [0096] internal diameter x of conduit 117 is about 8 mm. [0097] external diameter y of conduit 117 is about 13 mm. [0098] diameter z of port 125 is about 22 mm [0099] diameter p of outlet 21 is about 3-4 mm.

[0100] During assembly, regions 44, 46 of conduit 117 are seated on walls 128, 130 of port 125 with sleeve nut 124 pre-installed on conduit 117, the screw-threaded region 150 is engaged with screw-threaded wall 126 and the nut 124 tightened down to secure conduit 117 in position.

[0101] In use, cool compressed air is introduced into the assembly of FIG. 5 in the direction of arrow 170. The air flows within annular air gap 148 as illustrated by arrows 172, thereby cooling conduit 117 (and liquid formulation therein). The heated air then passes out of the assembly via outlet 162 as illustrated by arrows 174.

[0102] The assembly 200 of FIGS. 6a-6d is similar to that of FIGS. 5a and 5b. Assembly 200 includes a sleeve nut 224 which includes a head 240, a cylindrical body 246 and a region 250 which is screw-threaded and arranged to engage screw-threaded wall 126 (FIG. 5b) as described for the FIGS. 5a and 5b embodiment.

[0103] Head 240 includes an inlet 290 for compressed air and, diametrically opposed thereto, an outlet 292 (not shown in FIG. 6a but shown in FIGS. 6b and 6c).

[0104] Conduit 217 is modified compared to conduit 117 of FIGS. 5a and 5b. In this regard, the conduit 217 includes a central hollow hub 293 from which a series of elongate, radially-extending vanes 294 project. In FIG. 6c, six vanes 294 are illustrated, spaced apart at 60 around the hub 293.

[0105] Each vane 294 includes a step (along its elongate extent). Thus, each vane 294 includes a first thickness (measured radially) along a first portion 295 of its length and a second, wider thickness along a second portion 296 of its length. The increased thickness is arranged to fill a wider gap existing below nut 224 when the assembly 200 is fully assembled.

[0106] The vanes 294 co-operate to define passageways for compressed air. The passageways are defined between an outer surface of the conduit 217 and inwardly facing cylindrical wall 297 of cylindrical body 246 of sleeve nut 224. Beyond the distal ends 298 of the vanes an annular gap 299 is defined, the gap being defined inwards of annular region 244 of the conduit 217.

[0107] FIGS. 6b to 6d also include pin 228 which is movable within an elongate cylindrical opening in conduit 217 to close/open outlet 221.

[0108] In use, the assembly 200 is engaged in a port 125 as described for the FIGS. 5a and 5b embodiment. Then a compressed air supply is connected to inlet 290 and, in use, air is injected into the assembly. The air passes into the assembly as illustrated by arrows 300 in FIGS. 6b and 6c. It passes down passageways defined by vanes 294 and through gap 299. Thereafter, the air passes up passageways defined by vanes 294 and out of the assembly via outlet 292. The arrangement of the vanes 294, gap 299, inlet 290 and outlet 292 promotes the flow of the air towards and away from outlet 221. Consequently, heat is removed from regions of the conduit 117 which are expected to become hottest and/or which are close to regions of the conduit which are found, as described with reference to FIGS. 4a and 4b, to be where blockages of the conduit start.

[0109] The apparatus of FIGS. 5 and 6 were tested as described in Examples 2 and 3.

EXAMPLE 2

[0110] Using the test-rig described in Example 1, the apparatus of FIGS. 5 and 6 were assessed over a range of different compressed air flow rates. Results are provided in the table below.

TABLE-US-00002 Air flow rate Temperature adjacent injector tip ( C.) (litres/minute) Embodiment of FIG. 5 Embodiment of FIG. 6 No air 277 274 10 266 252 20 254 228 30 252 213

[0111] The results illustrate the preference to use air to cool the tip and that the embodiment of FIG. 6 is improved relative to that of FIG. 5.

EXAMPLE 3

[0112] The apparatus of FIGS. 5 and 6 was assessed, over a range of dosing rates, whilst injecting Formulation A1 into polymer in an extruder. In FIGS. 5 and 6, the air flow rate was litres/minute. Results are provided in the table below.

TABLE-US-00003 Dosing rate of Formulation A-1 Results (grams per minute of Embodiment Embodiment formulation delivered) of FIG. 5 of FIG. 6 2.91 No blockage No blockage 0.73 Instant blockage 20 minutes with one small blockage

[0113] Given that the lowest expected dosing rate of formulation A-1 in a production environment is approximately 2.92 grams per minute, both the embodiments of FIGS. 5 and 6 would be suitable for commercial use. For lower dose rates, the embodiment of FIG. 6 is preferred and/or the air flow rate may be increased.

[0114] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.