Patent Application
20230002934
This disclosure relates to meltblown equipment, meltblown products, and fabrication methods.
Nonwoven sheet products, such as, for example, vacuum bags, bath wipes, tea bag filters, are often made by a conventional fabrication method called melt blowing. The related production or manufacturing equipment may be referred to as meltblown equipment and the related products may be referred to as meltblown products. Typically, the fabrication method first melts a thermoplastic polymer into a liquid or flowable form, then extrudes the polymer through nozzles (also known as a die tip), and blows high speed and high temperature gases around the nozzles to fiberize the polymer and deposit the fiberized polymer on a surface, such as a substrate surface. The deposited polymer is allowed to cure and form a nonwoven fabric sheet. These nonwoven sheet products may be used in various applications, such as, for example, filtration, sorbents, apparels, and drug delivery applications.
Polymers having thermoplastic properties are suitable for melt blowing because of their characteristics in transition between the liquid and solid states. The transition temperature is known as glass transition temperature and varies from polymer to polymer. These polymers include, for example, polypropylene, polystyrene, polyesters, polyurethane, polyamides, polyethylene, and polycarbonate. Because these polymers have different glass transition temperatures and flow characteristics (e.g., viscosity, adhesiveness, etc.), meltblown equipment is often limited by their ability to produce products with certain uniformity, fiber size, or both. The polymer fiber uniformity is often limited by the uniformity of the high speed air surrounding the die tip. Furthermore, these specific limitations may lead to an overall limited production rate that caps productivity and economic viability of such products. The limitations are further magnified when two or more meltblown die tips are used together in a formation process involving wood pulp or other fibers, such as in a multiform process.
This disclosure describes melt blowing methods, assemblies, and systems that, in certain implementations, may improve one or more of product uniformity, fiber size, production rate, polymer production performance, and improved equipment and production operational efficiency. In one specific aspect, the disclosed meltblown die tip assembly produces more uniform high speed and high temperature airflows surrounding the die tip than traditional die tip assemblies. In certain implementations, the disclosed meltblown system produces more uniform output and reduced fiber sizes given certain polymer materials and production rates. More uniform output production efficiency may be achieved, in some implementations, through equipment design that allows for more thorough cleaning, and/or by having the equipment ready, such as on hot-standby, for replacement such that the maintenance down time can be lessened or minimized.
In general, the disclosed meltblown equipment includes a polymer beam and air chamber and a die tip assembly. The die tip assembly may be quickly attached, in certain implementations, onto or removed from the polymer beam and air chamber. The air chamber, along with an air feed system, may be included in an air heated beam for providing air to the die tip assembly. The air feed system can feed high velocity air though distribution holes to increase the heat transfer in the holes. The holes are located in locations to enable a corresponding structure (e.g., a plate) receiving the airflow to use the exiting air to increase the heat transfer efficiency. For example, the heat transfer efficiency may be increased on the die tip where airflow impinges, or at the air holes in the die tip, or both.
The die tip has airflows and drawn polymer converge at its nozzle, where highspeed uniform airflows of opposing sides entrain and draw out the polymer for fiberization. Because in certain implementations no fasteners or undesired obstructions are used in the airflow on polymer passageway or in or near the nozzle (as certain embodiments intentionally avoid such configurations with fasteners causing airflow obstructions), there is no disruption to the desired supply of air and/or polymer to the die tip nozzle. In particular, this disclosure shows an embodiment of a meltblown die tip structure that excludes any bolt head or countersink machined areas within approximately 10 cm (or 4″) of the nozzle exterior surface or in the airflow channels or passageways of the interior of the die's machined areas. This greatly enhances production and product uniformity.
In certain embodiments, the meltblown system includes a single input (e.g., a polymer material). The meltblown system may include tapered structures that facilitate flow of the input. Such tapered structures may be referred to as polymer distribution components. The assembly mechanisms used in some embodiments of the disclosed meltblown systems enable more convenient and thorough cleaning of the polymer distribution components with each use than traditional polymer distribution components. For example, when a mounting plate is used with the polymer distribution components, a single polymer seal (e.g., a single round seal may be used instead of a number of round seals or an elongated gasket on a channel) may be used. This allows for ease of cleaning offline in assembly areas and a simple installation in the machine. When no mounting plate is used, cleaning can be performed, in certain implementations, using a bottom plate of an air chamber or from a bottom access of the meltblown beam.
In specific instances, the die tip assembly used in the disclosed meltblown system is replaceable or interchangeable with another replacement die tip assembly, in a manner similar to cartridge replacement in printers. In other instances, the die tip assembly has air output that includes two streams of air entrained at a sharp or otherwise desired angle for the improved ability in producing fine polymer fibers. This may be dependent on the type of polymers being used and/or the type or desired characteristics of the product being produced. In yet some other instances, the die tip assembly also provides novel geometric settings, such as a setback distance and tip to tip distances, as further explained in the detailed description.
The disclosure presents one or more implementations of the die tip assembly that may provide other advantages over existing meltblown devices and methods. For example, the disclosed die tip assembly may provide a more optimized use of heated air in an non-obstructed manner. The die tip assembly, in certain implementations, may be adapted to compact sizes depending on specific requirements, such that two or more die tip assemblies can be arranged together during production, for example, in a configuration for combining with pulp fibers. In certain embodiments, the die tip assembly has a weld-in or machined-in strength rib structure for providing good geometric stability (examples provided in
In a first general aspect, a meltblown die tip assembly includes a mounting structure having at least one polymer flow passageway formed therein. The mounting structure is configured to receive a polymer flow, a first air passageway formed therein and configured to receive a first airflow, and a second air passageway formed therein and configured to receive a second airflow. The meltblown die tip assembly further includes an elongated die tip having a polymer flow chamber, a polymer flow tip, a first airflow regulation channel having a first impingement surface, a second airflow regulation channel having a second impingement surface, a first angled side, and a second angled side. The polymer flow chamber of the elongated die tip is in fluid communication with the at least one polymer flow passageway of the mounting structure at a first opening of the polymer flow chamber of the elongated die tip. The polymer flow chamber is configured to receive at least a portion of the polymer flow from the at least one polymer flow passageway of the mounting structure. The polymer flow chamber of the elongated die tip is in fluid communication with the elongated die tip at a first opening.
The polymer flow chamber of the elongated die tip is configured to receive at least a portion of the polymer flow from a first opening, the polymer flow chamber of the elongated die tip in fluid communication with the polymer flow tip at a second opening. The polymer flow tip is configured to receive at least a portion of the polymer flow from the polymer flow chamber at the second opening. The polymer flow tip, which may be considered the second opening in certain implementations, has a tip opening configured to dispense at least a portion of the polymer flow. The first airflow regulation channel is configured to receive the first airflow from the first air passageway of the mounting structure, regulate the first airflow using at least the first impingement surface, and dispense the first airflow adjacent the first angled side of the elongated die tip. The second airflow regulation channel is configured to receive the second airflow from the second air passageway of the mounting structure, regulate the second airflow using at least the second impingement surface, and dispense the second airflow adjacent the second angled side.
The meltblown die tip assembly further includes a first air plate positioned at least partially adjacent the first angled side of the elongated die tip and configured to form a first air exit passageway that is configured to receive the first airflow dispensed from the first airflow regulation channel of the elongated die tip and to dispense the first airflow adjacent the tip opening of the polymer flow tip and the at least a portion of the polymer flow to at least partially entrain such first airflow with the polymer flow. The assembly also includes a second air plate positioned at least partially adjacent the second angled side of the elongated die tip and configured to form a second air exit passageway that is configured to receive the second airflow dispensed from the second airflow regulation channel of the elongated die tip and to dispense the second airflow adjacent the tip opening of the polymer flow tip and the at least a portion of the polymer flow to at least partially entrain such second airflow with the polymer flow.
In some embodiments, the elongated die tip includes an impingement portion housing the first airflow regulation channel and the second airflow regulation channel. The first air regulation channel has a first impingement surface. The second airflow regulation channel has a second impingement surface. The first impingement surface and the second impingement surface assist with regulating the first airflow and the second airflow respectively. For example, the first impingement surface impinges or disrupts the first airflow in its initial traveling direction and thus forces the airflow to turn and reorganize or reassemble. In addition, the impact between the first airflow and the first impingement surface aids a transfer of energy from the first airflow to the impingement portion and thus the die tip. For example, the first and the second airflows may enter the meltblown system at a high temperature for maintaining the liquidity state of the polymer flow. The impingement portion, such as the first and the second impingement surfaces, provides a mechanism for efficient heat transfer and regulation of the uniformity of the first and the second airflows. In other embodiments, there may be multiple impingement surfaces in the airflow regulation channels.
In some other embodiments, the elongated die tip includes a neck portion narrower than the impingement portion and obstructing airflows exiting the first airflow regulation channel and the second airflow regulation channel.
In yet some other embodiments, the impingement portion includes a plurality of fastenable holes for receiving fasteners affixing the first air plate and the second air plate to the impingement portion of the elongated die tip. This may be achieved, using horizontally, vertically, or diagonally oriented fasteners, or combinations of the same.
In some embodiments, the elongated die tip and the first and the second air plates form a replaceable cartridge.
In some other embodiments, the meltblown die tip assembly further includes at least one breaker plate governing polymer flow from the polymer flow passageway of the mounting structure into the polymer flow chamber. The at least one breaker plate includes a plurality of holes for filtering and regulating the polymer flow. The at least one breaker plate can, in some embodiments, include two stacked breaker plates having one or more screen filter positioned between the two stacked breaker plates.
In yet some other embodiments, the first air plate and the second air plate are mounted onto the mounting structure using one or more fasteners that may be parallel to the polymer flow chamber.
In some embodiments, the first airflow regulation channel is configured to receive the first airflow from the first air passageway of the mounting structure, regulate the first airflow, transfer heat from the first airflow to the elongated die tip, and dispense the first airflow adjacent the first angled side of the elongated die tip; and wherein the second airflow regulation channel is configured to receive the second airflow from the second air passageway of the mounting structure, regulate the second airflow, transfer heat from the second airflow to the elongated die tip, and dispense the second airflow adjacent the second angled side of the elongated die tip.
In some other embodiments, the first and the second airflows cause the die tip assembly to maintain a temperature that maintains the polymer flow in a liquid state.
In yet some other embodiments, the polymer flow tip has an external angle of about 50 to about 90 degrees.
In some embodiments, the mounting structure and the elongated die tip are a unified piece. For example, the mounting structure and the elongated die tip may be considered a unified piece when bolted together, welded together, or otherwise combined or mounted (e.g., by adhesive). In other instances, the mounting structure and the elongated die tip are manufactured as one piece, which would also be considered a unified piece.
In some other embodiments, the elongated die tip further comprises an angled tip, the first air plate further comprises a first tip, and the second air plate further comprises a second tip, such that a vertical distance between the angled tip and a midpoint of the first tip and the second tip defines a setback dimension being about 0.5 mm to about 4.0 mm. A distance between the first tip and the second tip defines a tip-to-tip distance, such that a ratio of the setback dimension and the tip-to-tip distance is about 0.25 to about 2.5.
In yet some other embodiments, the at least one polymer flow passageway of the mounting structure includes an opening width near the first opening of the polymer flow chamber such that cleaning tools can access internal surfaces of the at least one polymer flow passageway of the mounting structure. The internal surfaces of the at least one polymer flow passageway of the mounting structure includes a tapered top surface for distributing the polymer flow.
In some embodiments, the first air plate includes a first outer surface. The second air plate includes a second outer surface. The first outer surface and the second outer surface form an angle between about 90 and about 140 degrees.
In some other embodiments, the meltblown die tip assembly further includes a meltblown beam fluidly connected with the mounting structure for supplying air and polymer. The meltblown beam and the mounting structure form a height above the die tip such that no other obstacle interferes with the surrounding air of the die tip in a region of control. The meltblown beam and the mounting structure are one unified piece.
In yet some other embodiments, the first airflow and the second airflow are entrained at a tip apex drawing the polymer flow and surrounding air such that no interfering structure is present within at least about 38 mm of the tip apex.
In some embodiments, the polymer flow chamber of the elongated die tip includes a rib structure connecting a first side wall of the polymer flow chamber to a second, opposing, side wall of the polymer flow chamber, wherein the rib structure has a cross sectional fluid dynamic shape to promote laminar flow in the polymer flow.
In some other embodiments, the first impingement surface is located at a top surface of the elongated die tip.
In yet some other embodiments, the first impingement surface is located within the first airflow regulation channel.
In a second general aspect, a die tip for polymer flow and air entrainment, the die tip may include a body portion, a polymer flow chamber, a polymer flow tip, a first airflow regulation channel, a first angled side, a second airflow regulation channel, and a second angled side opposed to the first angled side, the first angled side and the second angled side are positioned adjacent to or define the polymer flow tip. The polymer flow chamber receives a polymer flow and is configured to deliver the polymer flow to the polymer flow tip. The first airflow regulation channel receives a first airflow provided to the first angled side at accelerated speeds. The body portion includes at least one impingement surface impinging the first airflow for regulating the first airflow. The first angled side is provided adjacent to or defines part of the polymer flow tip such that the first airflow at accelerated speeds helps to draw and blows out the polymer flow from the polymer flow tip.
In some embodiments, the body portion includes a neck portion reducing a width of the body portion such that a transition surface from the neck portion to the first angled side impedes the first airflow exiting the first airflow regulation channel. The at least one impingement surface may include the transition surface.
In some other embodiments, the first angled side is adjacent a first air plate for directing and accelerating the first airflow impeded by the transition surface. The first airflow heats up the body portion of the die tip when the airflow impinges the transition surface impinges the airflow and help transfer heat from the first and second air flows to the die tip. The second airflow regulation channel receives a second airflow and sends the second airflow to the second angled side. The body portion includes a second impingement surface impinging a second airflow for regulating the second airflow in the second air regulation channel. The second airflow may be accelerated to a substantially same level of speeds as the first airflow when reached at the polymer flow tip such that both the first airflow and the second airflow are entrained to draw and blow out the polymer from the polymer flow tip.
In yet some other embodiments, the first airflow and the second airflow entrain to draw the polymer flow and blow or pull the polymer flow out of the polymer flow tip. In certain implementations, the first airflow and the second airflow are not impeded by or in contact with any fastener when the first airflow travels from the first airflow regulation channel to reach the polymer flow tip and the second airflow travels from the second airflow regulation channel to reach the polymer flow tip. The first airflow and the second airflow are not impeded for at least about 38 mm away from the polymer flow tip.
In some embodiments, the first air plate further includes a first tip, and the second air plate further includes a second tip, such that a vertical distance between the polymer flow tip and a midpoint of the first tip and the second tip defines a setback dimension being about 0.5 mm to about 4.0 mm. A distance between the first tip and the second tip defines a tip-to-tip distance, such that a ratio of the setback dimension and the tip-to-tip distance is about 0.25 to 2.5.
In a third general aspect, a meltblown die tip assembly includes a mounting structure having a polymer flow conduit and an airflow conduit. The meltblown die tip assembly includes a die tip at least partially sealingly attached to the mounting structure. The die tip receives a polymer flow from the polymer flow conduit of the mounting structure and receives an airflow from the airflow conduit of the mounting structure. The die tip includes an impingement surface receiving and reflecting the airflow to force the airflow to at least partially reassemble. An air plate is sealingly attached to the mounting structure and is mounted adjacent the die tip for providing a passage to accelerate the airflow exiting the die tip. The accelerated airflow draws the polymer flow from the die tip and fiberizes the polymer flow as desired.
In some embodiments, the die tip includes a second impingement surface between the die tip and the air plate, or in the die tip.
In a fourth general aspect, a method is disclosed for producing uniform or more uniform meltblown products by providing mere uniform airflows to a meltblown system. The method includes feeding pressurized air into one or more air passageways in a mounting structure to form a first airflow. The first airflow is impinged using a first impingement surface near an exit of the air passageway of the mounting structure. The first airflow impinged by the first impingement surface is then reassembled in a plenum or volume above or adjacent the first impingement surface. The reassembled first airflow passes into an air regulation channel. The reassembled first airflow is then accelerated to draw a polymer for melt blowing.
In some embodiments, the method further includes impinging the reassembled first airflow using a second impingement surface at a neck portion of a die tip and reassembling the first airflow impinged by the second impingement surface in a second plenum or volume above or adjacent the second impingement surface.
Detailed disclosure and examples are provided below.
Like elements are labeled using like numerals.
This disclosure presents a meltblown system having a die tip assembly, and related meltblown methods capable of producing highly uniform meltblown materials. The meltblown system, in one or more embodiments, provides advanced operation in handling polymer materials that usually pose limitations to conventional meltblown machines and methods, such as, for example, in terms of fiber size, porosity, among others. The disclosed meltblown system, in certain embodiments for a given certain throughput (as measured by volume or mass per length per unit time), can produce uniform or more uniform polymer products having reduced fiber sizes, which is important to a desired product quality. The meltblown system may also provide several operational benefits, such as easy cleaning, rapid tool changing, uniform heating or cooling, uniform polymer flowing, and others. Details of one or more implementations of a meltblown system are described below.
The die tip assembly 110 may include, in the example embodiment as shown, a mounting structure 112, a die tip 114, a first air plate 116, and a second air plate 118. The end plate 130 may assist with fastening these components of the die tip assembly 110 on an end. In some embodiments, another end plate (not shown) fastens certain components of the die tip assembly 110 on the other end. Specifically, the end plate 130 (as well as another end plate not shown) is fastenable to a frontal end of the elongated die tip 114, frontal ends of the two air plates 116 and 118, and a frontal end of the mounting structure 112 to have the assembly form a replacement cartridge such that the complete assembly can be quickly and conveniently replaced or exchanged while in hot standby mode without time-consuming dissembling of each component from the meltblown beam 120. The mounting structure 112 may include a polymer receiving conduit or hole 117 for receiving polymer from the beam 120. The mounting structure 112 also includes a slot or a number of holes 119 for receiving air. In some embodiments, the mounting structure includes two slots 119 and 126 positioned, in one implementation, symmetrically about the polymer receiving hole 117. Each of the slot 119 and 126 may include holes or conduits for providing air into the die tip assembly 110.
As further discussed below, the die tip 114 is assembled with the first air plate 116 and the second air plate 118 to create passages for airflow to accelerate to high speeds to perform the meltblowing process. The mounting structure 112 receives the polymer materials and air flow from the meltblown beam 120 and orderly feeds or directs them to the die tip 114 underneath. In some embodiments, the mounting structure 112 may be part of or integrated with the meltblown beam 120, and the die tip 114 and the first and the second air plates 116 and 118 are mounted below the mounting structure 112 of the meltblown beam 120. In some other embodiments, the mounting structure 112 may be part of the die tip 114 and receives the first and the second air plates 116 and 118. After assembly, the first air plate 116 and the second air plate 118 have a relatively large tip-to-tip distance. In some embodiments, the distance can be about 1.27 mm (or 0.05″), or in a range that includes such distance.
In
In the embodiment illustrated in
The breaker plates 210 and the filter 220 (if used) may be positioned anywhere along the polymer flow path, such as, for example, in an opening in the mounting structure 112 as shown in
Turning to
The mounting structure 112 has a top mounting surface 310 and a bottom mounting surface 320. The mounting structure 112 includes at least one polymer flow passageway 330, receive a polymer flow from the meltblown beam 120. The mounting structure 112 includes a first air passageway 340 formed therein. As aforementioned, in certain embodiments, the mounting structure 112 may be integrated with either the meltblown beam 120 or the die tip 114. For example, the top mounting surface 310 and the bottom mounting surface 320 may be nonexistent in different embodiments. The top mounting surface 310 may not exist when the mounting structure 112 is integrated with the meltblown beam 120. Alternatively, the bottom mounting surface 320 may not exist when the mounting structure 112 is part of the die tip 114. Having the mounting structure 112 as a separate piece, as in the embodiments shown in
The first air passageway 340 is configured to receive a first airflow from the meltblown beam 120. The mounting structure 112 further includes a second air passageway 342 formed therein. The second air passageway 342 receives a second airflow from the meltblown beam 120. In the embodiment illustrated, the first air passageway 340 and the second air passageway 342 are symmetrical about the polymer flow passageway 330. However, in other embodiments, the first and the second air passageways 340 and 342 may be placed at different locations, and/or may be offset in different planes.
The elongated die tip 114 is attached below the mounting structure 112 via, in certain implementations, at least partially through the first and the second air plates 116 and 118. The die tip 114 has a polymer flow chamber 350. The polymer flow chamber 350 receives polymer flow from the polymer flow passageway 330. The die tip 114 includes a body portion 360 and a polymer flow tip 372. The body portion 360 includes a first airflow regulation channel 352 and a second airflow regulation channel 354 disposed on opposing sides of the polymer flow chamber 350. The body portion 360 includes a first angled side 362 and a second angled side 364. The polymer flow tip 372 may be positioned a vertical distance away from an imaginary horizontal line between the tips of the first and the second air plates 116 and 118. This vertical distance is referred to as “setback,” which in one implementation may be about 0.5 mm (about 0.02″), or about 0.25 to about 2.5 times of the tip-to-tip distance (about 1.27 mm) of the first and the second air plates 116 and 118. In certain embodiments, the setback may be about 0.5-1.8 times of the tip-to-tip distance of the first and the second air plates 116 and 118.
As shown in
Temporarily turning to
In
Returning to
The first airflow regulation channel 352 is configured to receive the first airflow from the first air passageway 340 of the mounting structure 112. The first airflow regulation channel 352 regulates the first airflow and dispense the first airflow adjacent the first angled side 362. Similarly, the second airflow regulation channel 354 is configured to receive the second airflow from the second air passageway 342 of the mounting structure 112. The second air flow regulation channel 354 assists in regulating the second airflow and dispenses the second airflow adjacent the second angled side 364.
The first airflow regulation channel 352 and the second airflow regulation channel 354 regulate the respective first and second airflows by providing a restricted flow cross section along a direction, such as a uniform direction, such that the first and second airflows exit the first and second airflow regulation channels 352 and 354 at a calculated or desired accelerated speed. The exit speed corresponds to a known initial system pressure, such as the pressure provided to the system at the source of air.
In some embodiments, the elongated die tip 114 includes an impingement portion 361 housing the first airflow regulation channel 352 and the second airflow regulation channel 354. The first air regulation channel 352 has a first impingement surface 353. The second airflow regulation channel has a second impingement surface 355. The first impingement surface 353 and the second impingement surface 355 regulate the first airflow and the second airflow respectively. For example, the first impingement surface 353 impinges or disrupts the first airflow in its initial traveling direction and forces the airflow to turn and reorganize. In addition, the impact between the first airflow and the first impingement surface 353 aids a transfer of energy from the first airflow to the impingement portion 361 and thus the die tip 114. For example, the first and the second airflows may enter the meltblown system at a high temperature for maintaining the liquidity state of the polymer flow. The impingement portion 361 and the first and the second impingement surfaces 353 and 355 provide a mechanism for efficient heat transfer and regulating the uniformity of the first and the second airflows.
The first air plate 116 is positioned at least partially adjacent the first angled side 362 of the elongated die tip 114. The first air plate 116 is configured to form a first air exit passageway 382. The first air exit passageway 382 is configured to receive the first airflow dispensed from the first airflow regulation channel 352 of the elongated die tip 114. The first air exit passageway dispenses the first airflow adjacent the tip opening 374 of the polymer flow tip 372. The at least a portion of the polymer flow is at least partially entrained with such first airflow due to the high speeds of the first airflow. In some embodiments, the first airflow may exit the tip opening 374 at about up to 0.8 times of the speed of sound in air. In other embodiments, this speed may be in a range that includes up to 0.8 times the speed of sound in air.
In the embodiments illustrated in
In the embodiments shown in
In some embodiments, such as in
In one embodiment, the first airflow passageway 340 of the mounting structure 112 is not aligned with the first airflow regulation channel 352 such that the impingement portion 361 of the body portion 360 can decelerate and re-organize or reassemble the airflow before it is fed into the first airflow regulation channel 352. Such regulation effect resets the airflow dynamics so that the airflow dynamics in the first airflow regulation channel 352 is at least partially independent from the airflow dynamic of the first airflow passageway 340.
Similarly, the second airflow passageway 342 of the mounting structure 112 is not fully aligned with the second airflow regulation channel 354 such that the impingement portion 361 of the body portion 360 can decelerate and re-organize the airflow before it is fed into the second airflow regulation channel 354. This arrangement resets the airflow dynamics so that the airflow dynamics in the second airflow regulation channel 354 is different from the airflow dynamic of the second airflow passageway 342.
In addition, the body portion 360 of the die tip 114 includes a neck portion 365 that is narrower than the impingement portion 361. The neck portion 365 obstructs airflows exiting the first airflow regulation channel 352 and the second airflow regulation channel 354 using a transition surface 363 (e.g., a second impingement surface) extending from either side of the neck portion 365 to the first or the second angled side 362 and 364. As such, the neck portion 365 reduces a width of the body portion 360 such that a transition surface 363 extending from the neck portion 365 to the first angled side 362 impedes the first airflow exiting the first airflow regulation channel 352. The transition surface 363 thus can function as a second level impingement surface and regulates and reassemble the first or second airflow in similar manners as the impingement surfaces 353 and 355. The first angled side 362 is adjacent to a first air plate 116 for directing and accelerating the first airflow impeded by the transition surface 363.
The first airflow regulation channel 352 is configured to receive the first airflow from the first air passageway 340 of the mounting structure 112. The first airflow regulation channel 352 and the neck portion 365 regulate the first airflow and dispense the first airflow adjacent the first angled side 362 after deceleration and acceleration around the neck portion 361 and the transition surface 363, as described above. For example, in the embodiments illustrated in
The second airflow regulation channel 354 is also configured to receive the second airflow from the second air passageway 342 of the mounting structure 112. The second airflow regulation channel 354 and the neck portion 365 regulate the second airflow and dispense the second airflow adjacent the second angled side after deceleration and acceleration around the neck portion 361. The neck portion 365 effectively avoids, removes, or reduces formation of eddy flow in later development around the first and the second angled sides 362 and 364, thus achieving a more uniform and higher speed airflow. Both the neck portion 365 and the impingement portion 361 enable the body portion 360 to avoid, in certain implementations, from having any fastener interfering with the first or the second airflow from the first and second airflow passageways 340 and 342 to the tip opening 374.
Turning to specific features of each embodiment,
In the embodiment shown in
In operation, the first airflow and the second airflow may be accelerated, for example, to up to about 0.7 to about 0.8 Mach speed and heated to about 100 to about 375 degrees Celsius for fiberizing polymer fluids at the tip opening of the elongated die tip. The second airflow is accelerated to a substantially same level of speeds as the first airflow when reached at the polymer flow tip 372 such that both the first airflow and the second airflow are entrained to draw and blow out the polymer from the polymer flow tip 372. In some embodiments, the first airflow and the second airflow are entrained at a sharp or desired angle of about 50 degrees. In other embodiments, the first airflow and the second airflow are entrained at an angle greater than 50 degrees and less than 90 degrees. Correspondingly, the outer surfaces of the first and the second air plates 116 and 118 can form an angle of about 100 degrees to about 160 degrees.
The embodiments illustrated in
Turning now to
The reassembled first airflow 302 the travels into the air regulation channel 352 of the die tip 114 and enters a second volume or plenum 345 created between the neck portion 365 and the first air plate 116. Similarly, the second airflow 303 enters the second air passageway 342 and is reassembled in a first plenum 343 to become a reassembled airflow 304, which enters the second air regulation channel 354 and then reassembled again in a second plenum 346 created between the neck portion 365 and the second air plate 118. The second plenums 345 and 346 have a lower bound provided by the transition (second impingement) surface 363, which further disrupts and causing the airflows 301 and 303 to reassemble once more. As such, the uniformity of the airflows 301 and 303 is improved. The airflows 301 and 303 then enters and passes through a set of exit holes 369 and enters the air exit passage ways 382 and 383 respectively. The airflows 301 and 303 are accelerated in the air exit passage ways 382 and 383 to draw the polymer provided in the polymer flow tip 372 for melt blowing.
In some embodiments, the exit holes 369 below the transition surfaces 363 may be replaced with an equivelant structure, such as a gap (not illustrated) between the wide portion 375 that is under the neck portion 365 and either of the air plates 116 and 118. The gap may have a consistent width along the width (in the cross direction) of the die tip 114. Such configuration may avoid minor machining inconsistencies of the multiple exit holes 369 along the width of the die tip 114.
The second air plate 118 includes a second tip 409. The distance between the first tip 402 and the second tip 409 is defined as the tip-to-tip distance 404. The vertical distance between the angled tip 412 and both the first and the second tips 402 and 409 is defined as a set-back dimension 440. In some embodiments, the setback dimension 440 is between about 0.5 mm and 4.0 mm. In some embodiments, the ratio between the setback dimension 440 and the tip-to-tip distance 404 is a design parameter for achieving good meltblown performance. For example, the ratio of the setback dimension and the tip-to-tip distance is about 0.25 to 2.5.
Other implementations are possible. For example, although the meltblown process is commonly used for thermoplastic materials for producing non-woven fabric products, different polymers other than thermoplastic materials may be used with the disclosed equipment. For example, curable materials in their liquid form may be delivered onto a target substrate using the same apparatus or apparatus modified using the same working principles. In other instances, although the mounting structure 112 and the die tip 114 are illustrated as two separate structures, in other embodiments, they can be one integral structure to save additional sealing steps when the die tip 114 is fitted against the mounting structure 112. In some other embodiments, the die tip 114 and the first and the second air plates 116 and 118 may be fitted directly to the meltblown beam 120 without the intermediate mounting structure 112.
This application is a continuation of U.S. Non-Provisional patent application Ser. No. 16/198,703 filed on Nov. 21, 2018, which claims the benefits and priority of the U.S. Provisional Patent Application No. 62/590,037 filed on Nov. 22, 2017, the entire contents of which are incorporated herein by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 62590037 | Nov 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16198703 | Nov 2018 | US |
| Child | 17945853 | US |
