A METHOD TO PROVIDE MULTIFILAMENT BUNDLES OF MELT SPUN POLYMER FILAMENTS

Abstract

A method for providing a multifilament bundle of melt spun polymer filaments, the that includes providing a spinning device including at least M extruders for melting M polymers, M groups of spinning stations, each group comprising N spinning stations, each spinning station comprising and a spin pack coupled to a spin pump which receives molten polymer from one of the M extruders and spins a strand of filaments by pushing said polymer through the coupled spin pack, and N transformation stations for bundling M strands of filaments. The method further includes spinning N*M strands of filaments from the spinning stations at a given spin pump output and bundling the strands into N multifilament bundles via the N transformation stations whereby the spin pump outputs are varied over time.

Claims

1. A method for providing a multifilament bundle of melt spun polymer filaments, the method comprising: Providing a spinning device comprising At least M extruders for melting M polymers, wherein M>1; groups of spinning stations, each group comprising N spinning stations, wherein N>1, each of the N*M spinning stations comprising a spin pump and a spin pack coupled to the spin pump, where said spin pumps of each of the M groups receive a molten polymer from one of the M extruders and spin a strand of filaments by pushing said molten polymer through said coupled spin pack; N transformation stations for bundling M strands of filaments into a bundle, one strand from each of the M groups of spinning stations; Spinning out N*M strands from the N*M spinning stations at a given spin pump output for each of the spin pumps; bundling said strands of filaments into N multifilament bundles of melt spun polymer filaments by means of the N transformation stations, wherein each bundle comprises one strand of each of the M groups of spinning stations; whereby some or all of the spin pump outputs of the spin pumps are varied over time such that for each of the M groups of spinning stations, the sum of the spin pump outputs of the N spin pumps varies over time in a range of 5% v around the average sum of the spin pump of the group of N spinning stations.

2. The method according to claim 1, wherein for each of the N transformation stations, the sum of the spin pump outputs of the spin pumps is kept substantially constant over time.

3. The method according to claim 1, wherein M is 2, 3 or 4.

4. The method according to claim 1, wherein the M polymers are of a different color.

5. The method according to claim 1, wherein for each of the N transformation stations, the sum of the spin pump outputs of the spin pumps providing multifilament strands to the transformation station varies over time in a range of 2.5% v around the average sum of the spin pump outputs of the spin pumps providing multifilament strands to this transformation station.

6. The method according to claim 1, wherein N is in the range of from 2 to 50 or from 2 to 25.

7. The method according to claim 1, wherein each of the spinning stations further quenches the strand of filaments.

8. The method according to claim 1, wherein each of the transformation stations further elongates the bundle of filaments.

9. The method according to any claim 1 one of the preceding claims, wherein each of the transformation stations further texturizes the bundle of filaments.

10. The method according to claim 1, wherein each of the transformation stations further entangles the bundle of filaments at discrete lengths along the length of the bundle of filaments, thereby forming entanglements at discrete lengths along the length of the bundle of filaments, wherein the entanglements are spaced 1 to 20 cm apart.

11. A method for providing multifilament strands of melt spun polymer filaments, the method comprising Providing a spinning device comprising At least one extruder for melting a polymer; At least a group of N spinning stations, wherein N>1,each spinning station comprising a spin pump and a spin pack coupled to the this spin pump, wherein said spin pumps receive a molten polymer from the at least one extruder and spin a strand of filaments by pushing said molten polymer through said coupled spin pack; Spinning out N strands from the spinning stations of the group of N spinning stations at a given spin pump output for each spin pump; whereby some or all of the spin pump outputs of the spin pumps are varied over time, such that for the group of N spinning stations, the sum of the spin pump outputs of the N spin pumps varies over time in a range of 5% v around the average sum of the spin pump of the this group of these N spinning stations.

12. (canceled)

13. (canceled)

14. (canceled)

15. (canceled)

16. A method to provide multifilament bundles of melt spun polymer filaments, the method comprising Providing M groups of N multifilament strands of melt spun polymer filaments, wherein M>1; bundling M strands of filaments into N multifilament bundles of melt spun polymer filaments by means of the N transformation stations, wherein each bundle comprises one strand of each of the M groups of N spinning stations.

17. The method to provide multifilament bundles of melt spun polymer filaments according to claim 16, wherein for each of the N transformation stations, the sum of the spin pump outputs of the spin pumps providing multifilament strands to the transformation station varies over time in a range of 2.5% v around the average sum of the spin pump outputs of the spin pumps providing multifilament strands to this transformation station.

18. The method according to claim 1, wherein the color of the filaments of at least one of the strands within each of the N bundles provided by the transformation stations differs from the color of the filaments of the other strands.

19. The method to provide multifilament bundles of melt spun polymer filaments according to claim 11, wherein the method provides a first group of multifilament strands of melt spun polymer filaments and a second group of multifilament strands of melt spun polymer filaments.

20. The method to provide multifilament bundles of melt spun polymer filaments according to claim 19, wherein the method further comprises providing a third group of N multifilament strands of melt spun polymer filaments, and bundling each one of the first multifilament strands of the first group of multifilament strands to one multifilament strand of the second group of multifilament strands and one multifilament strand of the third group of multifilament strands to provide N multifilament bundles of melt spun polymer filaments.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0087] FIG. 1 is a schematic view of a system to implement the production method of a bundle of melt spun filaments according to the invention.

[0088] FIG. 2 is a schematic view of the spin pump output of the pumps used in the method of FIG. 1.

[0089] FIG. 3 shows schematically the cross sections of filaments present in a strand according to the invention.

[0090] The same reference signs refer to the same, similar or analogous elements in the different figures.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0091] The present invention will be described with respect to particular embodiments. It is to be noticed that the term “comprising”, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, steps or components as referred to, but does not preclude the presence or addition of one or more other features, steps or components, or groups thereof. Thus, the scope of the expression “a device comprising means A and B” should not be limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0092] Throughout this specification, reference to “one embodiment” or “an embodiment” are made. Such references indicate that a particular feature, described in relation to the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, though they could.

[0093] Furthermore, the particular features or characteristics may be combined in any suitable manner in one or more embodiments, as would be apparent to one of ordinary skill in the art.

[0094] A process to provide a yarn is shown in FIG. 1. As an example here, a yarn 300a or 300b comprising one bundle 200a or 200b is provided, which bundle comprises two strands 170a and 180a, respectively 170b and 180b of melt spun polymer filaments 172a and 182a, respectively 172b and 182b.

[0095] Four spinning station 100a, 101a, 100b and 101b are shown, each spinning station comprising a spin pack 110a, 130a, 110b, respectively 130b, each of them comprising a spin pump 112a, 112b, 132a respectively 132b, providing molten polymer to a spinneret 114a, 114b, 134a respectively 134b.

[0096] Spinning stations 100a and 100b belong to a first group of a number of spinning stations (of which 2 are shown), which receive molten polymer form extruder 102. Spinning stations 101a and 101b belong to a second group of a number of spinning stations (of which 2 are shown), which receive molten polymer form extruder 103.

[0097] A dye pack 116 which provides the dye to the molten polymer of extruder 102. A dye pack 136 which provides the dye to the molten polymer of extruder 103. The ratio polymer/dye is kept unchanged with changing polymer volumes pumped through the corresponding spin pump.

[0098] A control device 120 controls, via the settings of the spin pumps 112a, 112b, 132a and 132b, how much volume of polymer is spun through the spinnerets 114a, 114b, 134a and 134b per time unit. As shown in FIG. 1, the volume spun via spin pump 112a and 112b is stepwise but cyclically increased and decreased, the volume spun via spin pump 112a is alternatingly changed in comparison to the volume spun via spin pump 112b. In the meantime, and alternating with this variation in spun volume of pump 112a and 112b, the volume spun via spin pumps 132a and 132b are stepwise but also cyclically decreased and increased. The two variations of pumps 112a and 132a are tuned to each other such that the total volume of polymer spun by the two spin pumps, remains substantially constant. The two variations of pumps 112b and 132b are tuned to each other such that the total volume of polymer spun by the two spin pumps, remains substantially constant. The two variations of pumps 112a and 112b are tuned to each other such that the total volume of polymer taken from extruder 102 remains substantially constant. The two variations of pumps 132a and 132b are tuned to each other such that the total volume of polymer taken from extrude 103, remains substantially constant.

[0099] As a result, two times two strands of filaments (170a and 180a, and 170b and 180b) are spun out by the four spinning stations. The number of filaments (N) per strand are equal. The strands are quenched by quenching means 150.

[0100] Each group of spun filaments, being the strands 170a and 180a, respectively 170b and 180b, have, along the axis of the strand, a cyclically stepwise varying titer Td170 and Td180. This is shown in FIG. 2.

[0101] The two strands 170a and 180a are combined and provide the bundle 200a in transformation station 105a. All filaments 172a and 182a are extended and drawn at the same drawing ratio by a drawing installation 210a, e.g. one or more sets of godets. In the drawn bundle, the filaments 272a are obtained by reduction of titer of filaments 172a via drawing installation 210a. The filaments 282a are obtained by reduction of titer of filaments 182a via drawing installation 210a.

[0102] So in the drawn bundle 200a, along the axis of the strands, the filaments 272a and 282a have a cyclically stepwise varying titer Td272 and Td282, respectively. This is shown in FIG. 2.

[0103] After being drawn, the bundle 200a is texturized or “bulked” using a texturizing means 310a, and at regular distances along the length of the bundle, the filaments are entangled into knot 302a using an air entangling means 320a. As such a BCF yarn 300a is provided.

[0104] In a similar way, the two strands 170b and 180b are combined and provide the bundle 200b in transformation station 105b. All filaments 172b and 182b are extended and drawn at the same drawing ratio by a drawing installation 210b, e.g. one or more sets of godets. In the drawn bundle, the filaments 272b are obtained by reduction of titer of filaments 172b via drawing installation 210b. The filaments 282b are obtained by reduction of titer of filaments 182b via drawing installation 210b.

[0105] So in the drawn bundle 200b, along the axis of the strands, the filaments 272b and 282b have a cyclically stepwise varying titer Td272 and Td282, respectively. This is shown in FIG. 2.

[0106] After being drawn, the bundle 200b is texturized or “bulked” using a texturizing means 310b, and at regular distances along the length of the bundle, the filaments are entangled into knot 302b using an air entangling means 320b. As such a BCF yarn 300b is provided.

[0107] The titers (indicated in ordinate 1001) of various element are shown in FIG. 2. The filaments 170a and 180b have a titer along its length (indicated in abscissa 1000) a titer Td170a and Td180b which varies stepwise between the minimum value Tdmin and the maximum value Tdmax. The filaments 170b and 180a have a titer along its length (indicated in abscissa 1000) a titer Td170b and Td180a which varies stepwise between the minimum value Tdmin and the maximum value Tdmax, but varies opposite to titer Td170a and Td180b. The average titer of the filaments in the strand is indicated Tda.

[0108] This change in titers of the filaments is related in a one to one basis to the volumes of the spin pumps used to make the filaments. Also shown in FIG. 2, the volumes (indicated in ordinate 1002) of various spin pumps are shown in FIG. 2. The spin pumps 112a and 132b spin a volume over time (indicated in abscissa 1003) being V112a and V132b which varies stepwise between the minimum value Vmin and the maximum value Vmax. The spin pumps 112b and 132a spin a volume over time (indicated in abscissa 1003) being V120b and V132a which varies stepwise between the minimum value Vmin and the maximum value Vmax. As can be noticed in FIG. 2, the volume of polymer material provided by the extruder 102, being V112a +V112b, is substantially constant over time. The volume of polymer material provided by the extruder 103, being V132a +V132b, is substantially constant over time. The strands themselves have a titer being the multiplication of the filament titer Td170a, Td170b, Td180a or Td180b with the number of filaments in the strand. Hence the strand titer also cyclically varies and the variation of the strand titer and the filament titers are proportional.

[0109] After the filaments are reduced in titer with a drawing ratio DR, the filaments 272a, 272b, 282a and 282b have a titer along its length being a titer Td272a, Td272b, Td282a and Td282b which varies stepwise between the minimum value Tdmin/DR and the maximum value Tdmax/DR.

[0110] The titer of the bundle 200a or 200b after drawing, and of the yarn 300a and 300b after texturizing and air entangling, is shown as Tdb, which equals “(L×(Td272a+Td282a))/DR”, L being the number of filaments in the strands. Tdb is substantially identical along the length of the bundle or yarn.

[0111] As an example, polyamide is used to provide the two spin packs with molten polymer. In each spin pack, the polymer, molten to a temperature of 250° C., is spun out through a spinneret with 75 spin openings. In the first spin pack, a blue colorant is added at a ratio of 3%. In the second spin pack, a green colorant is added at a ratio of 4%.

[0112] The filaments spun have cyclically, stepwise varying titer because the spin pumps are set to have a controlled, accordingly varying spin pump output. The titer of the spun filaments vary between +/−40% denier. The spin pumps are synchronized such that the total volume of polymer spun by both pumps remain constant.

[0113] The two stands are combined to a bundle of two times 75 filaments from each strand, i.e. 150 filaments in the bundle, which bundle is drawn at a drawing ratio 2.5. The titer of the spun filaments vary between 12.1 and 5.2 denier, while the bundle titer is substantially constant at 1300. The bundle is texturized by most commonly air or steam and every 3 cm, a knot is provided by air entangling. This results in a BCF yarn with a titer of 1300 denier.

[0114] Because of the two distinct colors, the yarn has zones which show more green because in this section of the yarn, the green filaments of the one strand are thicker hence provide relatively a higher volume to the yarn in this section. The yarn has also zones which show more blue because in this section of the yarn, the blue filaments of the one strand are thicker hence provide relatively a higher volume to the yarn in this section.

[0115] It is understood that for the scheme shown in FIG. 1, there are 2 groups of spinning stations, each group comprising 2 spinning stations, i.e. the first group comprising spinning stations 100a and 100b, the second group comprising spinning stations 101a and 101b. This because two extruders are used to provide molten polymer to the spinning stations. Possibly, 3 or more extruders are used. Each group may comprise 3 or more, i.e. a plurality of spinning stations. As an example, three extruders and three groups of spinning stations may be provided. Each group may comprise e.g. 24 spinning pumps and hence 24 spinning stations. The sum of the volume spun out by these 24 spin pumps over time may vary about 5% v over the average these 24 spin pumps displace per time, and preferably is about constant. A too large increase of polymer displacement of one or more of these 24 spin pumps is to be compensated to some extent by a reduction of polymer displacement by one or more other spin pumps of this group. The control unit 120 is to adjust the volumes displaced by each of these 24 spin pumps.

[0116] As there are in this example three extruders provide, there are 24 transformation stations provided, each transformation station receiving 3 strands of filaments, one strand from each group of spinning stations. Possibly, as further shown in FIG. 3, the three strands of filaments in each of the transformation stations are provided such that the titer of the bundle provided by this transformation station is kept substantially constant. This means that for each cluster of three spin pumps feeding one transformation station, one spin pump belonging to one of the three groups of spinning stations, the sum of the volumes of polymer displaced by these spin pumps is kept substantially constant. The control unit 120 can be set to adjust the volumes displaced by each of these 3 spin pumps. As the volumes displaced by each of the 24 spin pumps of each of the three groups of spinning stations is to be controlled a set out above, the control unit will have to adjust the polymer volumes spun out (or displaced) by each of these 3 times 24 spin pumps. A memory storage unit or an algorithm driven feed may provide the spin pump settings for each spin pump n function of time.

[0117] A schematic view of the possible variations of cross sections of the filament, strand and bundle for one of the 24 transformation stations, made using a method according to the invention, is given in FIG. 3.

[0118] A multifilament bundle of three multifilament strands is made, each strand comprising 75 trilobal filaments of PA6. The cross section of one filament 10101, 10102 respectively 10103 of each strand is shown in FIG. 2. The color of the filaments of the three strands are different. Filaments 10101 are reddish in color, filaments 10102 are yellowish, while filaments 10103 are blueish.

[0119] At a first section A, the three strands all have filaments having the average filament titer. The volumetric amount of filaments present in each color is represented in the pie chart 10100A. All colors are present in the same amount, providing the bundle a given brownish color.

[0120] In a second section B, the filament titer of strand 10101 is reduced, while the titer of the filaments of the strand 10103 is increased. The titer of filaments 10102 remain as in section A. The average titer of the bundle remains constant and identical to the bundle titer at section A. As such, less polymer, hence color of strand 10101 and more of strand 10103 is present, resulting in a color at that position in the bundle having a higher color component of strand 10103. At that position, the bundle has a color with a rather blue-greenish color.

[0121] In a second section C, the filament titer of strand 10102 is reduced, while the titer of the filaments of the strand 10103 is increased. The titer of filaments 10101 remain as in section A. The average titer of the bundle remains constant and identical to the bundle titer at section A. As such, less polymer, hence color of strand 10102 and more of strand 10103 is present, resulting in a color at that position in the bundle having a higher color component of strand 10103. At that position, the bundle has a color with a rather blue-burgundy-like color.

[0122] In a similar way, in sections D to G, each time one filament titer is reduced while another is increased, causing a different color to be present for the bundle with a more red, blue or yellow color tone, while the average bundle titer remains substantially constant along the length of the bundle.

[0123] Along the whole length of the bundle, the bundle titer remains substantially constant, being the sum of the titers of the three times 75 filaments of the three strands.

[0124] Instead of bundles having a different color, bundles with different dyability for one or more dyes can be combined in the very same way. Once the textile product (bundle, yarns, greige product, etc.) is dyed, the very same effect in color variation is obtained.

[0125] It is to be understood that although preferred embodiments and/or materials have been discussed for providing embodiments according to the present invention, various modifications or changes may be made without departing from the scope and spirit of this invention.