Patent Application
20180127893
Producing different colored polyethylene terephthalate (PET) (e.g., using virgin and/or recycled PET) for use in the production of products (e.g., such as carpet or other products) may result in unnecessary waste. Accordingly, there is a need to develop improved coloring systems for PET.
A method of manufacturing colored bulked continuous carpet filament from a polymer melt comprising polyethylene terephthalate (PET) using liquid colorant, in particular embodiments, comprises: (A) providing a static mixing assembly comprising between twenty and forty static mixers; (B) providing a liquid metering system; (C) providing a first liquid colorant having a first color; (D) using the liquid metering system to inject the first liquid into the polymer melt; (E) after the step of using the liquid metering system to inject the first liquid colorant into the polymer melt, passing the polymer melt and the first liquid colorant through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant; and (F) after the step of passing the polymer melt through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant, forming the polymer melt into bulked continuous carpet filament having a color based on the first color.
A method of manufacturing colored bulked continuous carpet filament from recycled polyethylene terephthalate (PET) bottles using a single multi-screw extruder, in various embodiments, comprises: (A) providing a plurality of recycled PET bottles; (B) grinding the plurality of recycled PET bottles into a group of polymer flakes, the group of flakes comprising a first plurality of flakes that consist essentially of PET and a second plurality of flakes that do not consist essentially of PET; (C) washing the group of polymer flakes to remove at least a portion of one or more contaminants from a surface of the polymer flakes; (D) after the step of washing the first plurality of flakes: (i) scanning the washed group of flakes to identify the second plurality of flakes, and (ii) separating the second plurality of flakes from the first plurality of flakes.
In particular embodiments, the method further comprises: providing a multi-screw extruder that comprises: (i) a first satellite screw extruder, the first satellite screw extruder comprising a first satellite screw that is mounted to rotate about a central axis of the first satellite screw; (ii) a second satellite screw extruder, the second satellite screw extruder comprising a second satellite screw that is mounted to rotate about a central axis of the second satellite screw; (iii) a third satellite screw extruder, the third satellite screw extruder comprising a third satellite screw that is mounted to rotate about a central axis of the third satellite screw; (iv) a fourth satellite screw extruder, the fourth satellite screw extruder comprising a fourth satellite screw that is mounted to rotate about a central axis of the fourth satellite screw; and (v) a pressure regulation system that is adapted to maintain a pressure within the first, second, third, and fourth satellite screw extruders between about 0 millibars and about 25 millibars.
In various embodiments, the method further comprises: (A) using the pressure regulation system to reduce a pressure within the first, second, third, and fourth satellite screw extruders to between about 0 millibars and about 25 millibars; and (B) using the multi-screw extruder to at least partially melt the first plurality of flakes into a polymer melt and at least partially purify the polymer melt by, while maintaining the pressure within the first, second, third, and fourth satellite screw extruders between about 0 millibars and about 5 millibars, passing the polymer melt through the multi-screw extruder so that: (1) a first portion of the melt passes through the first satellite screw extruder, (2) a second portion of the melt passes through the second satellite screw extruder, (3) a third portion of the melt passes through the third satellite screw extruder, and (4) a fourth portion of the melt passes through the fourth satellite screw extruder.
In some embodiments, the method further comprises: (A) providing a liquid metering system; (B) providing a first liquid colorant having a first color; (C) after the step of using the multi-screw extruder to at least partially melt the first plurality of flakes into the polymer melt and at least partially purify the polymer melt, using the liquid metering system to inject the first liquid into the polymer melt; (D) providing a static mixing assembly; (E) passing the polymer melt and the first liquid colorant through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant; and (F) after the step of passing the polymer melt through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant, forming the polymer melt into bulked continuous carpet filament having a color based on the first color.
A method of manufacturing colored bulked continuous carpet filament, in various embodiments, comprises providing a multi-screw extruder that comprises: (A) a first satellite screw extruder, the first satellite screw extruder comprising a first satellite screw that is mounted to rotate about a central axis of the first satellite screw; (B) a second satellite screw extruder, the second satellite screw extruder comprising a second satellite screw that is mounted to rotate about a central axis of the second satellite screw; and (C) a pressure regulation system that is adapted to maintain a pressure within the first and second satellite screw extruders between about 0 millibars and about 10 millibars. In particular embodiments, the method further comprises: (A) using the pressure regulation system to reduce a pressure within the first and second satellite screw extruders to between about 0 millibars and about 10 millibars; and (B) while maintaining the pressure within the first and second satellite screw extruders between about 0 millibars and about 10 millibars, passing a melt comprising recycled polymer through the multi-screw extruder so that: (1) a first portion of the melt passes through the first satellite screw extruder, and (2) a second portion of the melt passes through the second satellite screw extruder.
In further embodiments, the method of manufacturing colored bulked continuous carpet filament further comprises: (A) providing a liquid metering system; (B) providing a first liquid colorant having a first color; (C) after the step of passing the polymer melt through the multi-screw extruder, using the liquid metering system to inject the first liquid into the polymer melt; (D) providing a static mixing assembly comprising at least twenty individual static mixing elements; (E) passing the polymer melt and the first liquid colorant through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant; and (F) after the step of passing the polymer melt through the static mixing assembly to substantially thoroughly mix the polymer melt with the first liquid colorant, forming the polymer melt into bulked continuous carpet filament having a color based on the first color.
Having described various embodiments in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
Various embodiments will now be described in greater detail. It should be understood that the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
Overview
New processes for producing and coloring fiber from recycled polymer (e.g., recycled PET polymer) and virgin polymer (e.g., virgin PET polymer) are described below. In various embodiments, these new processes may include, for example: (1) extruding a polymer (e.g., such as PET) using a primary extruder; (2) adding a colorant to the extruded polymer downstream from the primary extruder (e.g., a liquid colorant injected into the extruded polymer via one or more liquid metering systems); (3) using one or more static mixers (e.g., up to thirty six static mixers) to substantially uniformly mix the extruded polymer and the added colorant; and (4) using a spinning machine to spin the uniformly mixed extruded polymer and added colorant into bulked continuous filament (e.g., carpet yarn) that has a color that is based on the added colorant. The process described herein may, for example, reduce an amount of waste related to changing a color of bulked continuous filament produced using a particular extruder when switching to a different colorant.
In various embodiments, this new process may, for example: (1) produce less waste than other processes when producing or changing a color of bulked continuous filament produced using a particular extruder or from a particular polymer stream; (2) facilitate the production of small batches of particular colors of filament (e.g., for use in rugs or less popular colors of carpet) at a relatively low cost; (3) increase a number of simultaneous filament colors that a single extruder can produce; and (4) etc. In at least one embodiment, the improved process results in reduction of waste of up to about 4000 pounds of fiber when switching from a first color to a second color (e.g., by adding the colorant downstream from the primary extruder rather than upstream). In some embodiments, the use of liquid colorant may result in a savings of about two cents per pound of fiber (e.g., over processes that utilize one or more color concentrates).
II. More Detailed Discussion
Step 1: Using an Extrusion System to Melt and Purify PET
In various embodiments, the step of using an extrusion system to melt and purify PET (e.g., PET flakes and/or pellets) comprises: (A) preparing the PET for extrusion; and (B) using a suitable extruder to melt and purify the PET.
Preparing the PET for Extrusion
In particular embodiments, the step of preparing the PET for extrusion may vary based on a source of the PET. For example, in various embodiments, the process may utilize: (1) virgin PET (e.g., virgin PET pellets); (2) recycled PET (e.g., recycled PET flakes ground from recycled PET bottles and other suitable sources); and/or (3) a combination of virgin and recycled PET. In various embodiments in which the process utilizes recycled PET, the step of preparing the PET for extrusion may include sorting, grinding, washing and other steps designed to remove any impurities from the recycled PET prior to extrusion. These other PET preparation steps may, for example, be unnecessary in embodiments of the process that utilize virgin PET. Because using recycled PET in the process described herein may contribute to even further costs savings to those associated with a reduction in waste due to colorant changing, the process will be described below particularly with respect to recycled PET.
In a particular embodiment, preparing the PET for extrusion may include preparing flakes of PET polymer from post-consumer bottles or other sources of recycled PET. An exemplary process for preparing post-consumer bottles for use in the production of bulked continuous filament is described in U.S. Pat. No. 8,597,553 B1, entitled “Systems and Methods for Manufacturing Bulked Continuous Filament” and published on Dec. 3, 2013, which is hereby incorporated herein in its entirety. Generally speaking, the step of preparing flakes of PET polymer from post-consumer bottles may comprise, for example: (A) sorting post-consumer PET bottles and grinding the bottles into flakes; (B) washing the flakes; and (C) identifying and removing any impurities or impure flakes.
Sorting Post-Consumer PET Bottles and Grinding the Bottles into Flakes
In particular embodiments, bales of clear and mixed colored recycled post-consumer (e.g., “curbside”) PET bottles (or other containers) obtained from various recycling facilities make-up the post-consumer PET containers for use in the process. In other embodiments, the source of the post-consumer PET containers may be returned ‘deposit’ bottles (e.g., PET bottles whose price includes a deposit that is returned to a customer when the customer returns the bottle after consuming the bottle's contents). The curbside or returned “post-consumer” or “recycled” containers may contain a small level of non-PET contaminates. The contaminants in the containers may include, for example, non-PET polymeric contaminants (e.g., PVC, PLA, PP, PE, PS, PA, etc.), metal (e.g., ferrous and non-ferrous metal), paper, cardboard, sand, glass or other unwanted materials that may find their way into the collection of recycled PET. The non-PET contaminants may be removed from the desired PET components, for example, through one or more of the various processes described below.
In particular embodiments, smaller components and debris (e.g., components and debris greater than 2 inches in size) are removed from the whole bottles via a rotating trammel. Various metal removal magnets and eddy current systems may be incorporated into the process to remove any metal contaminants. Near Infra-Red optical sorting equipment such as the NRT Multi Sort IR machine from Bulk Handling Systems Company of Eugene, Oreg., or the Spyder IR machine from National Recovery Technologies of Nashville, Tenn., may be utilized to remove any loose polymeric contaminants that may be mixed in with the PET flakes (e.g., PVC, PLA, PP, PE, PS, and PA). Additionally, automated X-ray sorting equipment such as a VINYLCYCLE machine from National Recovery Technologies of Nashville, Tenn. may be utilized to remove remaining PVC contaminants.
In particular embodiments, the sorted material is taken through a granulation step (e.g., using a 50B Granulator machine from Cumberland Engineering Corporation of New Berlin, Wis.) to size reduce (e.g., grind) the bottles down to a size of less than one half of an inch. In various embodiments, the bottle labels are removed from the resultant “dirty flake” (e.g., the PET flakes formed during the granulation step) via an air separation system prior to entering the wash process.
Washing the Flakes
In particular embodiments, the “dirty flake” is then mixed into a series of wash tanks. As part of the wash process, in various embodiments, an aqueous density separation is utilized to separate the olefin bottle caps (which may, for example, be present in the “dirty flake” as remnants from recycled PET bottles) from the higher specific gravity PET flakes. In particular embodiments, the flakes are washed in a heated caustic bath to about 190 degrees Fahrenheit. In particular embodiments, the caustic bath is maintained at a concentration of between about 0.6% and about 1.2% sodium hydroxide. In various embodiments, soap surfactants as well as defoaming agents are added to the caustic bath, for example, to further increase the separation and cleaning of the flakes. A double rinse system then washes the caustic from the flakes.
In various embodiments, the flake is centrifugally dewatered and then dried with hot air to at least substantially remove any surface moisture. The resultant “clean flake” is then processed through an electrostatic separation system (e.g., an electrostatic separator from Carpco, Inc. of Jacksonville, Fla.) and a flake metal detection system (e.g., an MSS Metal Sorting System) to further remove any metal contaminants that remain in the flake. In particular embodiments, an air separation step removes any remaining label from the clean flake. In various embodiments, an electro-optical flake sorter based at least in part on Raman technology (e.g., a Powersort 200 from Unisensor Sensorsysteme GmbH of Karlsruhe, Germany) performs the final polymer separation to remove any non-PET polymers remaining in the flake. This step may also further remove any remaining metal contaminants and color contaminants.
In various embodiments, the combination of these steps delivers substantially clean (e.g., clean) PET bottle flake comprising less than about 50 parts per million PVC (e.g., 25 ppm PVC) and less than about 15 parts per million metals for use in the downstream extrusion process described below.
Identifying and Removing Impurities and Impure Flakes
In particular embodiments, after the flakes are washed, they are fed down a conveyor and scanned with a high-speed laser system 300. In various embodiments, particular lasers that make up the high-speed laser system 300 are configured to detect the presence of particular contaminates (e.g., PVC or Aluminum). Flakes that are identified as not consisting essentially of PET may be blown from the main stream of flakes with air jets. In various embodiments, the resulting level of non-PET flakes is less than 25 ppm.
In various embodiments, the system is adapted to ensure that the PET polymer being processed into filament is substantially free of water (e.g., entirely free of water). In a particular embodiment, the flakes are placed into a pre-conditioner for between about 20 and about 40 minutes (e.g., about 30 minutes) during which the pre-conditioner blows the surface water off of the flakes. In particular embodiments, interstitial water remains within the flakes. In various embodiments, these “wet” flakes (e.g., flakes comprising interstitial water) may then be fed into an extruder (e.g., as described below), which includes a vacuum setup designed to remove—among other things—the interstitial water that remains present in the flakes following the quick-drying process described above.
Using an Extrusion System to Melt and Purify PET Flakes
As may be understood from
As may be understood from
The resultant polymer melt (e.g., comprising the melted PET), in various embodiments, is then fed into the extruder's MRS section 420, in which the extruder separates the melt flow into a plurality of different streams (e.g., 4, 6, 8, or more streams) through a plurality of open chambers.
As shown in
In various embodiments, as may be understood from
In various embodiments, the MRS extruder's MRS Section 420 is fitted with a vacuum pump that is attached to a vacuum attachment portion 422 of the MRS section 420 so that the vacuum pump is in communication with the interior of the MRS section via a suitable opening 424 in the MRS section's housing. In still other embodiments, the MRS Section 420 is fitted with a series of vacuum pumps. In particular embodiments, the vacuum pump is configured to reduce the pressure within the interior of the MRS Section 420 to a pressure that is between about 0.5 millibars and about 25 millibars. In particular embodiments, the vacuum pump is configured to reduce the pressure in the MRS Section 420 to less than about 5 millibars (e.g., about 1.8 millibars or less). The low-pressure vacuum created by the vacuum pump in the MRS Section 420 may remove, for example: (1) volatile organics present in the melted polymer as the melted polymer passes through the MRS Section 420; and/or (2) at least a portion of any interstitial water that was present in the wet flakes when the wet flakes entered the MRS Extruder 400. In various embodiments, the low-pressure vacuum removes substantially all (e.g., all) of the water and contaminants from the polymer stream.
In some embodiments, after the molten polymer is run the through the multi-stream MRS Section 420, the streams of molten polymer are recombined and flow into the MRS extruder's second single screw section 440. In particular embodiments, passage through the low pressure MRS Section 420 purifies the recycled polymer melt (e.g., by removing the contaminants and interstitial water) and makes the recycled polymer substantially structurally similar to (e.g., structurally the same as) pure virgin PET polymer. In particular embodiments, the resulting polymer is a recycled PET polymer (e.g., obtained 100% from post-consumer PET products, such as PET bottles or containers) having a polymer quality that is suitable for use in producing PET carpet filament using substantially only (e.g., only) PET from recycled PET products.
Step 2: Add a Colorant to the Polymer Melt Downstream from the Primary Extruder
In particular embodiments, after the recycled PET polymer (e.g., or virgin PET) has been extruded and purified by the above-described extrusion process, a colorant is added to the resultant polymer melt. As shown in
In particular embodiments, Colorant A 204 may comprise pelletized color concentrate which the secondary extruder 208 is configured to at least partially melt prior to adding Colorant A 204 to the polymer melt. In various other embodiments, Colorant A 204 may comprise other additives such as, for example, a carrier resin which may aid in binding the colorant to the polymer. In other embodiments, Colorant A 204 may include any suitable liquid colorant which may be pumped into the polymer melt using any suitable pump (e.g., in lieu of using a secondary extruder 206 and pelletized color concentrate).
In various embodiments, the process may further include monitoring an amount of throughput (e.g., polymer output) from the primary extruder 202 in order to determine an appropriate amount of letdown (e.g., an appropriate let down ratio) such that a proper amount of Colorant A 204 is added to the polymer melt downstream from the primary extruder 202. In various embodiments, a desirable letdown ratio may include a letdown ration of between about two percent and about eight percent. In other embodiments, the letdown ratio may include any other suitable letdown ratio (e.g., one percent, two percent, three percent, four percent, five percent, six percent, seven percent, etc.). In particular embodiments, the letdown ratio may vary based on a desired color of bulked continuous filament ultimately produced using the process (e.g., up to about twenty percent).
In various embodiments, adding the colorant 204 downstream of the primary extruder 202 may save on waste during color changeover. For example, when switching between producing bulked continuous filament of a first color to producing bulked continuous filament of a second color, it is necessary to change the colorant 204 added to the polymer melt (e.g., from a first colorant that would result in bulked continuous filament of the first color to a second colorant that would result in bulked continuous filament of the second color). As may be understood by one skilled in the art, after switching from adding the first colorant to the polymer melt to adding the second colorant to the polymer melt, residual first colorant may remain in in the system between the point in the process at which the colorant is added and the spinning machine 212. For example, residual first colorant may remain in the secondary extruder 206, the one or more static mixers 208, or any other physical mechanism used in the process (such as any mechanism shown in
As may be understood by one skilled in the art, after running the process with the second colorant for a suitable amount of time, the bulked continuous filament produced by the process will eventually be of the second, desired color (e.g., because the first colorant will eventually be substantially flushed out the system). Between the point at which there is a changeover in adding the second colorant to the process rather than the first colorant and the point at which the process begins to produce the desired color of bulked continuous filament, the process will produce some waste bulked continuous filament that is of an undesired color (e.g., due at least in part to the residual first colorant).
In various embodiments, the waste bulked continuous filament produced using the process described herein may be considerably lower than waste bulked continuous filament produced during color changeovers using other processes (e.g., such as other processes in which colorant is added to PET prior to extrusion in a primary extruder such as an MRS extruder). For example, in various embodiment, the process described herein may limit waste bulked continuous filament to an amount of bulked continuous filament produced when running a single package of colorant (e.g., of the second colorant), which may, for example, result in less than about 100 pounds of waste. In particular embodiments, reducing waste may lead to cost saving in the production of bulked continuous filament.
Step 3: Use One or More Static Mixers to Mix Polymer Melt with Added Colorant
In particular embodiments, following the addition of Colorant A 204 to the stream of molten polymer, the process includes the use of one or more static mixers 208 (e.g., one or more static mixing elements) to mix and disperse Colorant A 204 throughout the polymer stream. As may be understood by one skilled in the art, due in part to the viscosity of the polymer stream (e.g., polymer melt), when a dye or other colorant is added to the polymer stream, the dye and the stream may not mix. In various embodiments, the flow of the polymer melt is substantially laminar (e.g., laminar) which may, for example, further lead to a lack of mixing.
In particular embodiments, the one or more static mixers 208 shown in
In various other embodiments, the one or more static mixers 208 may comprise a suitable static mixer comprising one or more suitable helical mixing elements.
As may be further understood from
In particular embodiments, the one or more static mixers 208 may comprise any suitable number and combination of any suitable static mixing element descried herein. For example, in particular embodiments, the one or more static mixers 208 comprise up to thirty six individual static mixing elements (e.g., thirty six static mixing elements, thirty four static mixing elements, etc.). In still other embodiments, the one or more static mixers 208 comprise any other suitable number of static mixing elements sufficient to substantially uniformly (e.g., homogeneously) mix the molten polymer with the added colorant (e.g., to substantially uniformly mix the molten polymer and the added colorant into a colored melt stream 530 as shown in
In particular emboldens, the one or more static mixers 208 may comprise any suitable combination of static mixing elements (e.g., types of static mixers), such as, for example, any suitable break down of the static mixer 700 shown in
Step 4: Use of a Spinning Machine to Turn the Colored Polymer into Filament
Referring back to
In particular embodiments, the spinning machine 212 used in the process described above is the Sytec One spinning machine manufactured by Oerlikon Neumag of Neumuenster, Germany. The Sytec One machine may be especially adapted for hard-to-run fibers, such as nylon or solution-dyed fibers, where the filaments are prone to breakage during processing. In various embodiments, the Sytec One machine keeps the runs downstream of the spinneret as straight as possible, uses only one threadline, and is designed to be quick to rethread when there are filament breaks.
Although the example described above describes using the Sytec One spinning machine to produce carpet yarn filament from the polymer, it should be understood that any other suitable spinning machine may be used. Such spinning machines may include, for example, any suitable one-threadline or three-threadline spinning machine made by Oerlikon Neumag of Neumuenster, Germany or any other company.
In various embodiments, prior to using the spinning machine 212 to spin the colored melt into filament, the process may utilize one or more color sensors 210 to determine a color of the colored melt. In various embodiments, the one or more color sensors 210 comprises one or more spectrographs configured to separate light shone through the polymer melt into a frequency spectrum to determine the color of the polymer melt. In still other embodiments, the one or more color sensors 210 comprises one or more cameras or other suitable imaging devices configured to determine a color of the resultant polymer melt. In particular embodiments, in response to determining that the color of the polymer melt is a color other than a desired color (e.g., the polymer melt is lighter than desired, darker than desired, a color other than the desired color, etc.) the system may: (1) discard the portion of the stream with the incorrect color; and/or (2) adjust an amount of colorant 204 that is added to the flake and/or the polymer melt upstream in order to adjust a color of the resultant polymer melt. In particular embodiments, adjusting the amount of colorant 204 is executed in a substantially automated manner (e.g., automatically) using the one or more color sensors 210 in a computer-controlled feedback control loop.
Producing a Plurality of Different Colored Fibers Using a Single Primary Extruder
In addition to the single colorant added to a single polymer stream from a primary extruder 202 described above with respect to
As shown in this Figure, a colorant (e.g., Colorant A-D 204a-d) is added to each individual polymer stream, for example, using a respective extruder 206a-d as described above. For example, Colorant C 204 is added to individual polymer stream 203c using extruder 206c.
Once the respective Colorant A-D 204a-d has been added to the respective individual polymer stream 203a-d, each individual polymer stream 203a-d with added Colorant A-D 204a-d is substantially uniformly mixed using respective one or more static mixers 208a-d. For example, once Colorant D 204d has been added to individual polymer stream 203d, the resultant colorant/polymer mixture passes through the one or more static mixers 208d to mix the Colorant D 204d and individual polymer stream 203d (e.g., to substantial homogeneity). Following mixture by the one or more static mixers 208a-d, the resultant respective colored melt streams are spun into filament using respective spinning machines 212a-d.
In various embodiments, it may be important to monitor the output of the extruder to determine a throughput of each individual polymer stream 203a-d. In such embodiments, monitoring throughput may ensure that each individual polymer stream 203a-d has the proper color letdown ratio in order to add a proper amount of Colorant A-D 204a-d to achieve a desired color of bulked continuous filament.
As may be understood from
Various embodiments of a process for producing various colored bulked continuous filament may include features that vary from or are in addition to those described above. Exemplary alternative embodiments are described below.
Addition of Liquid Colorant to Melt Stream Using Pump
More Detailed Discussion of the Use of Liquid Colorant in Combination with a Static Mixing Assembly
In particular embodiments, the liquid colorant 216 may comprise any suitable liquid colorant 216, which may, for example, have any suitable pigment. In a particular example, the liquid colorant may comprise any suitable pigment produced by BASF of Ludwigshafen, Germany. In various embodiments, the liquid colorant may comprise any suitable titanium dioxide colorant. In a particular embodiment, the liquid colorant comprises a ColorMatrix liquid colorant produced by the PolyOne Corporation of Avon Lake, Ohio.
In various embodiments, the use of liquid colorant 216 may result in more consistent color formulations of the BCF produced using the process described herein when compared to BCF produced from molten polymer mixed with a pelletized color concentrate (e.g., as described above). Because a liquid metering system 214 (e.g., such as the liquid metering system described below) may be configured to inject as little as a single drop of liquid colorant 216 at a time, a process that utilizes liquid colorant 216 may be better suited for producing consistent color BCF than a system that utilizes color pellets (e.g., because the system that utilizes color pellets may only change an amount of color added to a polymer melt in pellet-sized increments).
In other embodiments the use of liquid colorants may provide for high color consistency between batches of BCF colored with a liquid colorant. In various embodiments, the use of liquid colorant may result in a reduction in wastage (e.g., of the liquid colorant) as a result of high dosing accuracy (e.g., which may be achieved using the liquid metering system 214 described below) and high product recovery rates. In still other embodiments, liquid colorants may be relatively highly concentrated, which may, for example, enable the process to utilize a low addition rate to the polymer melt in order to achieve a desired color. In some embodiments, the addition rate may be, for example, between about two percent and about six percent by weight to the polymer melt.
As discussed above, any process described herein may utilize a liquid metering system 214 to inject the liquid colorant 216 into the polymer melt 203. In a particular embodiment, the process may utilize one or more Polyone ColorMatrix FlexCart Liquid Metering Systems manufactured by the PolyOne Corporation of Avon Lake, Ohio.
In various embodiments, the liquid metering system 214 is configured to provide flexible metering of liquid colorant 216 to the polymer melt 203. For example, the liquid metering system 214 may comprise one or more suitable pumps for delivering (e.g., injecting) liquid colorant 216 into the polymer melt 203. In particular embodiments, the one or more suitable pumps may comprise, for example, one or more peristaltic pumps (e.g., which may be used for short production runs and frequent color changes), one or more progressing cavity pumps (e.g., which may be used for longer production runs in extrusion applications), and/or any other suitable pump or combination of pumps. In various embodiments, the one or more pumps may be interchangeable (e.g., the liquid metering system 214 may be configured to enable a user to exchange one or more of the one or more pumps for a new type of pump or a clean replacement of a similar pump).
In particular embodiments, the liquid metering system 214 comprises a cassette, which may, for example, house a reservoir (e.g., for storing liquid colorant), the one or more pumps, and one or more delivery tubes. In various embodiments, the cassette may comprise one or more reservoirs which may, for example, be configured to hold one or more different colored liquid colorants. In particular embodiments, the liquid metering system 214 may comprise a tote tank of up to about 25 different colored liquid colorants. In various embodiments, the liquid metering system 214 is configured to combine the different colored liquid colorants in different ratios in order to produce different desired bulked continuous filament color.
In various embodiments, the liquid metering system 214 comprises a suitable control system (e.g., comprising a computer controller, processor, etc.), which may, for example, be configured to control operation of the one or more pumps. In particular embodiments, the control system may be configured to control operation of the one or more pumps in order to cause the one or more pumps to deliver the liquid colorant 216 to the polymer melt 203 at a particular rate (e.g., a particular flow rate). In various embodiments, the control system is configured to operate the liquid metering system 214 to inject the liquid colorant at a metering rate of up to about 10 cubic centimeters per second (e.g., 10 cubic centimeters per second). In some embodiments, the liquid metering system 214 is configured to deliver a substantially continuous injection of liquid colorant 216 into the polymer melt 203 at a substantially consistent rate (e.g., which may, for example, ensure that the bulked continuous filament produced by the process has a relatively consistent color).
As described more fully above, after the step of injecting a liquid colorant 216 into the polymer melt 203 using the liquid metering system 214, the process, in various embodiments, comprises passing the polymer melt and the liquid colorant 216 through the static mixing assembly 208. In particular embodiments, the static mixing assembly 208 comprises any suitable combination of static mixers (e.g., static mixing elements) described herein. In a particular embodiment, the static mixing assembly 208 comprises at least about twenty static mixers (e.g., at least twenty static mixers). In other embodiments, the static mixing assembly 208 comprises between about twenty static mixing elements (e.g., twenty static mixers) and about forty static mixing elements (e.g., forty static mixers). In other embodiments, the static mixing assembly 208 comprises between about thirty two static mixing elements (e.g., thirty two static mixers) and about forty static mixing elements (e.g., forty static mixers). In a particular embodiment, the static mixing assembly 208 comprises forty static mixers. In still other embodiments, the static mixing assembly 208 comprises any suitable number of static mixers (e.g., static mixing elements) to sufficiently thoroughly mix (e.g., uniformly mix) the polymer melt 203 with the liquid colorant 216 (e.g., sufficiently thoroughly mixed to ensure that the resulting filament produced by the process has a substantially uniform color).
In various embodiments, a flow of the polymer melt and liquid colorant as the mixture approaches the static mixing assembly 208 may be substantially laminar (e.g., laminar). As such, the polymer melt and liquid colorant may not mix when the liquid colorant is added to (e.g., injected into) the polymer melt. In particular embodiments, the static mixing assembly 208 is configured to disrupt the flow of the liquid colorant and polymer melt to sufficiently thoroughly mix (e.g., uniformly mix) the polymer melt 203 with the liquid colorant 216 (e.g., sufficiently thoroughly mixed to ensure that the resulting filament produced by the process has a substantially uniform color). This may, for example, result in a more disrupted flow as the mixture passes through each progressive static mixer in the static mixing assembly 208.
In particular embodiments, the process described herein is configured to produce a sufficiently uniform mixture of the liquid colorant 216 and polymer melt 203 prior to spinning in the spinning machine 212 without the use of one or more dynamic mixers or dynamic mixing elements. In this way, the process may rely on mechanical mixing produced by the static mixing assembly 208 as the polymer melt/liquid colorant mixture passes through the static mixing assembly 208. In some embodiments, not using dynamic mixers may further reduce production costs for the colored bulked continuous filament (e.g., through power conservation, savings on equipment costs, etc.).
In particular embodiments, the process described above may be suitable for producing limited runs of bulked continuous filament of a particular color. This may, for example, enable a product line to produce a limited run amount of bulked continuous filament in a made-to-order manner (e.g., in any suitable desired color). In particular embodiments, the process is configured to produce bulked continuous filament in a manner that reduces waste produced when switching from a first liquid colorant having a first color to a second liquid colorant having a second color.
For example, when switching between producing bulked continuous filament of a first color to producing bulked continuous filament of a second color, it may be necessary to change the liquid colorant 216 added to the polymer melt (e.g., from a first liquid colorant that would result in bulked continuous filament of the first color to a second liquid colorant that would result in bulked continuous filament of the second color). As may be understood by one skilled in the art, after switching from adding the first liquid colorant to the polymer melt to adding the second liquid colorant to the polymer melt, residual first liquid colorant may remain in in the system between the point in the process at which the first liquid colorant is added and the spinning machine 212. For example, residual first colorant may remain in the static mixing assembly 208, the polymer melt 203, the liquid metering system 216, or any other physical mechanism used in the process (such as any mechanism shown in
As may be understood by one skilled in the art, in various embodiments, after running the process with the second colorant for a suitable amount of time, the bulked continuous filament produced by the process will eventually be of the second, desired color (e.g., because the first colorant will eventually be substantially flushed out the system). Between the point at which there is a changeover in adding the second colorant to the process rather than the first colorant and the point at which the process begins to produce the desired color of bulked continuous filament, the process will produce some waste bulked continuous filament that is of an undesired color (e.g., due at least in part to the residual first colorant).
As may be understood from
In other embodiments, the system may be configured to substantially immediately begin to inject the second liquid colorant into the polymer melt after ceasing to inject the first liquid colorant. In such embodiments, the system may be configured to reduce an amount of waste polymer (e.g., waste BCF).
In particular embodiments, the time between the control system ceasing injection of the first liquid colorant and a time at which the process begins to produce a properly colored fiber in the second, desired color following the introduction of the second liquid colorant may define a color changeover time. In various embodiments, the bulked continuous fiber produced during the color changeover time may comprise bulked continuous filament in a waste color (e.g., in a color other than the first or second color). In various embodiments, bulked continuous filament in the waste color may be unsuitable for use (e.g., may not be suitable for use in producing carpet, may not be suitable for running through the recycling process described above, etc.). In some embodiments, the bulked continuous filament produced in the waste color may be true waste in that any costs associated with its production may not be recuperated.
In particular embodiments, the color changeover time may be up to about six minutes. In other embodiments, the color changeover time may be up to about ten minutes, or any other suitable time. In various embodiments, the system is configured to produce at least a particular amount of bulked continuous filament following ceasing injecting the first liquid colorant prior to beginning to inject the second liquid colorant. In a particular embodiments, the process comprises producing one doff of yarn (e.g., BCF) prior to beginning to inject the second liquid colorant. In a particular embodiments, a doff may include a set of full-size yarn packages produced by one filament extrusion (e.g., spinning) machine. In other embodiments, such as embodiments in which the system is configured to substantially immediately begin injecting the second liquid colorant after ceasing to inject the first liquid colorant, the system may be configured to produce one doff of waste BCF during the changeover time.
In particular embodiments, the process may further reduce a changeover time from a first color to a second color and increase cost savings by, for example, exchanging one or more internal components of the liquid metering system when beginning to run a second color (e.g., such as the one or more pumps, fittings, etc.), or taking any other suitable cost or time-saving measure.
In various embodiments, the waste bulked continuous filament produced using the process described herein may be considerably lower than waste bulked continuous filament produced during color changeovers using other processes (e.g., such as other processes in which colorant is added to PET prior to extrusion in a primary extruder such as an MRS extruder). For example, in various embodiment, the process described herein may limit waste bulked continuous filament to an amount of bulked continuous filament produced in a single doff of BCF. In some embodiments, the use of liquid colorant may result in a savings of about two cents per pound of fiber (e.g., over processes that utilize one or more color concentrates or other techniques).
Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Also, while various embodiments are discussed above in regard to producing carpet filament from PET, similar techniques may be used to produce carpet filament from other polymers. Similarly, while various embodiments are discussed above in regard to producing carpet filament from PET, similar techniques may be used to produce other products from PET or other polymers. For example, various other methods may utilize one or more steps described herein to add liquid or other colorant to a polymer other than PET (e.g., such as PTT, polystyrene, polyvinyl, nylon, etc.). In such embodiments, a system and/or method may utilize one or more static mixers in order to at least partially (e.g., uniformly mix) the non-PET polymer with a suitable liquid or other colorant.
In addition, it should be understood that various embodiments may omit any of the steps described above or add additional steps. Furthermore, any numerical ranges described herein are intended to capture every integer and fractional value within the described range (e.g., every rational number value within the described range). For example, it should be understood that a range describing a letdown ratio of between about two percent and about eight percent is intended to capture and disclose every rational number value percentage between two percent and eight percent (e.g., 2%, 3%, 4%, 5%, 6%, 7%, 8%, 2.1%, 2.01%, 2.001% . . . 7.999% and so on). Additionally, terms such as ‘about’, ‘substantially’, etc., when used to modify structural descriptions or numerical values are intended to capture the stated shape, value, etc. as well as account for slight variations as a result of, for example, manufacturing tolerances. For example, the term ‘substantially rectangular’ is intended to describe shapes that are both exactly rectangular (e.g., have four sides that meet at ninety degree angles) as well as shapes that are not quite exactly rectangular (e.g., shapes having four sides that meet at an angle in an acceptable tolerance of ninety degrees, such as 90°+/−4°)
In light of the above, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for the purposes of limitation.
This application is a continuation-in-part of U.S. patent application Ser. No. 15/348,591, entitled “Polyethylene Terephthalate Coloring Systems Methods,” filed Nov. 10, 2016, which is hereby incorporated herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15348591 | Nov 2016 | US |
| Child | 15804501 | US |
