Device for dispensing a composition Device for dispensing a composition

Abstract

An apparatus and method for dispensing a composition is provided, the apparatus comprising a barrel (120) having an inlet (128) and an outlet (129), a screw (122) received in the barrel, and a drive mechanism operably coupled to a shank end (134) of the screw to rotate the screw. The screw is hollow and comprises both an inner surface and an outer surface, the inner surface defining a cavity (142) adjacent the outlet, and wherein the screw further comprises a plurality of apertures (140) through which the cavity and the outer surface communicate with one another. The apertures are positioned along a perforated portion (146) of the cavity, wherein the perforated portion can have an increasing lateral dimension away from the shank end. The apertures can also provide an increasing aperture area relative to the outer surface of the screw away from the shank end. The screw can further comprise a helical thread (132) having a raised thread section (150) and one or more lowered thread sections (152), wherein the apertures are at least partially located on the lowered thread sections.

Description

TECHNICAL FIELD

[0001] Dispensers for polymer compositions, particularly those capable of dispensing polymer compositions continuously, and related methods and dispensing systems are provided. BACKGROUND

[0002] Screw dispensers are commonly used as feed mechanisms for polymer materials in continuous manufacturing or converting operations. These machines use a rotating screw housed within a cylindrical barrel. The barrel includes an inlet, typically at the top of the barrel, and an outlet at the end of the barrel. Along its length, the barrel can include one or more resistive heating elements that can be precisely controlled.

[0003] These dispensers typically receive and convert feed material that contains one or more polymers. The feed material can include one or more thermoplastic resins that are solid at ambient temperature. After being fed into the dispenser through the inlet, the feed material is heated above its melting temperature by a combination of heat conduction along the barrel wall and high pressure and friction generated by the rotating screw. The feed material is thus metered, melted, and mixed as it is conveyed along the length of the barrel by the rotating screw, and ultimately discharged from the distal end of the barrel through the outlet.

[0004] The screw can be operated at a predetermined speed using a motor drive unit and a gear box. Temperature controllers are connected to heating and / or cooling elements at one or more zones along the barrel to maintain a set point temperature. The ability of the screw and barrel assembly to extrude a given material is based on the properties or configuration of the barrel and screw, the properties of the composition being dispensed, and the conditions under which the system is operated. SUMMARY

[0005] A number of design considerations and tradeoffs are considered when configuring single screw dispensers, particularly for applications requiring accurate metering of large amounts of material. Moving large amounts of material typically requires either enlarging the size of the screw and barrel or increasing the rotational speed of the screw. Enlarging the size of the machine greatly increases the weight and cost. Faster screw speeds typically increase the torque levels and can require larger drive motors, which also increases the weight and cost.

[0006] Another issue relates to heat transfer. In order to effectively dispense solid thermoplastics, their temperature must be raised above their melting temperature. Heat can be transferred through the barrel, but the rate of heat transfer is limited by the residence time of the thermoplastics within the dispenser. In these cases, the length of the dispenser is often increased to provide sufficient time to melt the thermoplastics. In addition, the dispenser must contend with a heterogeneous mixture of solids of various sizes being agitated in a liquid melt, raising the issue of how to effectively deliver heat to the solids without overheating the melt.

[0007] An automated dispensing solution is provided herein using a hollow core screw that provides an unconventional flow path that gradually separates the solid and liquid portions of a composition in a manner that mitigates many of these technical challenges. Surprisingly, the provided screw can provide similar or greater throughput than a conventional single screw dispenser, but with significantly reduced shear and significantly reduced torque. The reduced torque stems from an increase in the amount of air in the outward channel of the screw, and allows for a smaller and lighter drive motor. The reduction in weight in turn can allow the dispenser to be mounted on a smaller and more cost effective robotic arm in an automated manufacturing process.

[0008] Operation of the provided dispenser also provides sustainability benefits. The increased surface area and flow path of the hollow core screw can improve heat transfer, and can provide improved melting at lower extruder temperatures to reduce power consumption. Faster melting can allow for higher throughput without the need for longer screws / barrels. Reduced shear on the composition can also reduce thermal degradation, improve quality while reducing waste.

[0009] It has been found that the provided apparatus can be particularly suitable for use in point of use dispensing of pressure sensitive adhesives, as previously described in copending U.S. Provisional Patent Application Nos. 62 / 810,221 (Napierala et al.), 62 / 810,248 (Napierala et al.), and 62 / 907,325 (Napierala et al.).

[0010] In a first aspect, an apparatus for dispensing a composition is provided. The apparatus includes a barrel having an inlet and an outlet, a screw received in the barrel, the screw having a distal end and a shank end, and a drive mechanism operably coupled to the shank end and capable of rotating the screw within the barrel. The screw is hollow and includes both an inner surface defining a cavity adjacent the outlet, and an outer surface, and wherein the screw further includes a plurality of apertures through which the cavity and the outer surface communicate with one another. The plurality of apertures are positioned along a perforated portion of the cavity, and the perforated portion can have a lateral dimension that increases as it moves away from the shank end.

[0011] In a second aspect, an apparatus for dispensing a composition is provided, the apparatus comprising: a barrel having an inlet and an outlet; a screw received in the barrel, the screw having a distal end and a shank end; and a drive mechanism operably coupled to the shank end and capable of rotating the screw within the barrel. The screw is hollow and includes both an inner surface defining a cavity adjacent the outlet, and an outer surface, and wherein the screw further includes a plurality of apertures through which the cavity and the outer surface communicate with one another. The screw includes a helical thread extending about an axis, and the helical thread can include a raised thread section and one or more lowered thread sections adjacent the raised thread section, the raised and lowered thread sections extending parallel to one another along the helical thread. The lowered thread section can be distal to the raised thread section and adjacent an exposed surface of the axis, wherein the plurality of apertures are at least partially located on the one or more lowered thread sections.

[0012] In a third aspect, an apparatus for dispensing a composition is provided, the apparatus comprising: a barrel having an inlet and an outlet; a screw received in the barrel, the screw having a distal end and a shank end; and a drive mechanism operably coupled to the shank end and capable of rotating the screw within the barrel. The screw is hollow and includes both an inner surface defining a cavity adjacent the outlet, and an outer surface, and wherein the screw further includes a plurality of apertures through which the cavity and the outer surface communicate with one another. The plurality of apertures are positioned along a perforated portion of the cavity, and the perforated portion can have an increasing aperture area relative to the outer surface of the screw as distal from the shank end.

[0013] In a fourth aspect, a screw having a distal end and a shank end for use with an apparatus for dispensing a composition is provided. The apparatus includes: a barrel having an inlet and an outlet; and a drive mechanism operably coupled to the shank end and capable of rotating the screw within the barrel. The screw includes: an axis; a helical thread extending about the axis, wherein the axis is hollow and includes both an inner surface defining a cavity adjacent the outlet, and an outer surface; and a plurality of apertures through which the cavity and the outer surface communicate with one another. The plurality of apertures are positioned along a perforated portion of the cavity, the perforated portion having an increasing lateral dimension as distal from the shank end.

[0014] In a fifth aspect, a screw is provided having a distal end and a handle end for use with an apparatus for dispensing a composition. The apparatus includes a barrel having an inlet and an outlet, and a drive mechanism operably coupled to the handle end and capable of rotating the screw within the barrel. The screw includes a shaft, a helical flight extending around the shaft, wherein the shaft is hollow and includes both an inner surface defining a cavity adjacent the outlet and an outer surface, and a plurality of apertures through which the cavity and the outer surface communicate with one another. The helical flight includes a raised flight section and one or more lowered flight sections adjacent the raised flight section, the raised and lowered flight sections extending parallel to one another along the helical flight. The lowered flight section can be distal to the raised flight section and adjacent an exposed surface of the shaft, wherein the plurality of apertures are at least partially located on the one or more lowered flight sections.

[0015] In a sixth aspect, a screw is provided having a distal end and a handle end for use with an apparatus for dispensing a composition. The apparatus includes a barrel having an inlet and an outlet, and a drive mechanism operably coupled to the handle end and capable of rotating the screw within the barrel. The screw includes a shaft, a helical flight extending around the shaft, wherein the shaft is hollow and includes both an inner surface defining a cavity adjacent the outlet and an outer surface, and a plurality of apertures through which the cavity and the outer surface communicate with one another. The plurality of apertures are positioned along a perforated portion of the cavity, and the perforated portion can have an increasing aperture area relative to the outer surface of the screw as it moves away from the handle end.

[0016] In a seventh aspect, a method of dispensing a composition using the apparatus is provided. The method includes feeding the composition into the inlet of the barrel, rotating the screw to transport the composition toward the distal end of the screw and generate sufficient pressure to push the composition through the plurality of apertures and into the cavity, and expelling the composition from the cavity through the outlet of the barrel. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a schematic view of a dispensing system according to one exemplary embodiment.

[0018] Figure 2 is a cross-sectional view of a dispensing apparatus that can be used in a dispensing system of Figure 1 according to an exemplary embodiment.

[0019] Figure 3 is a front side view of a screw for use in a dispensing apparatus of Figure 2 according to one embodiment.

[0020] Figure 4 is a cross-sectional side view of a screw of Figure 3 according to one exemplary embodiment.

[0021] Figure 5 is a cross-sectional side view of a portion of the screw shown in the insert of Figure 4 Figure 5

[0022] Figure 6 is a front side view of a screw that can be used in a dispensing apparatus according to an alternative embodiment of Figure 2

[0023] Figure 7 is a cross-sectional side view of a screw of Figure 6

[0024] Figure 8 is a cross-sectional side view of a portion of the screw shown in the insert of Figure 6 Figure 8

[0025] Reference signs that have been repeated in the description and in the drawings are intended to denote identical or similar features or elements throughout the disclosure. It will be appreciated that those of ordinary skill in the art can design many alternative modifications and embodiments within the scope and spirit of the principles of the disclosure. The drawings can not be to scale.

[0026] Definitions

[0027] “ambient temperature” means at a temperature of 22 degrees Celsius.

[0028] “non-tacky” refers to a material that passes the “self-stick test” in which the force required to peel the material from itself is equal to or less than a predetermined maximum threshold amount without fracturing the material. The self-stick test is described in International Patent Publication No. WO 2019 / 164678 (Nyaribo et al.) and is typically performed on a sample of the skin material to determine whether the skin is non-tacky.

[0029] ​​​​​​"Pressure sensitive adhesive" refers to a material that is normally tacky at room temperature and can be adhered to a surface by the application of slight finger pressure, and thus can be distinguished from other types of non-pressure sensitive adhesives. A general description of pressure sensitive adhesives can be found in the Encyclopedia of Polymer Science and Engineering, Vol. 13, Wiley-Interscience Publishers (New York, 1988). Additional descriptions of pressure sensitive adhesives can be found in the Encyclopedia of Polymer Science and Technology, Vol. 1, Interscience Publishers (New York, 1964). As used herein, "pressure sensitive adhesive" or "PSA" refers to a viscoelastic material that has the following properties: (1) strong and permanent tack, (2) adhesion to a substrate under no more than finger pressure, and (3) cohesive strength sufficient to permit clean release from a substrate. Pressure sensitive adhesives can also meet the Dahlquist criteria described in the Handbook of Pressure-Sensitive Adhesive Technology, D. Satas, 2ndEdition, p. 172 (1989). This criteria defines a pressure sensitive adhesive as one that has a creep compliance of greater than 1 x 10 -6 cm 2 / dyne at one second.

[0030] "Screw length" refers to the length of the threaded portion of an extrusion screw (typically the portion that is in contact with the extrudate), but does not include the shank. DETAILED DESCRIPTION

[0031] As used herein, the terms "preferred" and "preferably" refer to embodiments of the present description that can provide certain benefits under certain circumstances. However, other embodiments can also be preferred under the same or other circumstances. Additionally, the statement of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude those other embodiments from the scope of the application.

[0032] As used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a” or “the” component can include one or more components or equivalents thereof known to those skilled in the art. In addition, the term “and / or” means one or all of the listed elements or a combination of any two or more of the listed elements.

[0033] Notably, the terms “comprising,” “including,” and variations thereof do not have a limiting meaning when used in referring to the accompanying description. Also, “one,” “an,” “the,” “at least one,” and “one or more” are used interchangeably herein. Relative terms such as left, right, forward, rearward, top, bottom, side, upper, lower, horizontal, vertical, and the like can be used herein and, if so, are from the perspective observed in a particular figure. These terms are used only to simplify description, however, and not to limit the scope of the invention in any way.

[0034] References throughout this specification to “one implementation,” “certain implementations,” “one or more implementations” or “an implementation” mean that a particular feature, structure, material, or characteristic described in connection with the implementation is included in at least one implementation of the application. Thus, the appearances of the phrases, such as “in one or more implementations,” “in certain implementations,” “in one implementation,” or “in an implementation,” throughout this specification are not necessarily all referring to the same implementation of the application. Trade names are listed in all capital letters, where applicable.

[0035] Described herein is a dispensing apparatus and systems and methods thereof for continuously dispensing a polymeric feed in molten form. The dispensed composition is optionally a pressure sensitive adhesive. The dispensing apparatus can be made very compact and operate in an environment where there is essentially zero back pressure at the outlet of the dispenser.

[0036] Figure 1 is a schematic view of an exemplary dispensing system 100 that includes a dispensing apparatus 102 mounted to the end of a moveable arm 104. The moveable arm 104 is adhered to a base 106, which can be part of a table or other platform. The moveable arm 104 can have any number of joints 105 to allow the dispensing apparatus 102 to translate and rotate in up to six degrees of freedom. The moveable arm 104, which can be controlled manually or automatically, allows the dispensing apparatus 102 to dispense adhesive composition precisely and reproducibly over a wide range of positions relative to the base 106.

[0037] Optionally and as shown, the dispensing system 100 includes a filament adhesive 108 that can be continuously fed into the dispensing apparatus 102, asFigure 1 The filament adhesive 108 can be continuously unwound from the spool 114 as shown. It will be appreciated that the location of the spool 114 relative to other components of the dispensing system 100 is not critical and can be mounted at a convenient location. The spool 114 can be affixed to the base 106 or to the structure to which the base 106 is typically mounted.

[0038] Figure 1 The dispensing apparatus 102 is shown dispensing a molten composition 110 in hot-melt form onto a bonding surface of a given substrate 112. The substrate 112 is not necessarily limited and can be, for example, an industrial part to be adhesively coupled to an assembly. As one option, the substrate 112 can be mounted to the base 106, thereby providing a spatial reference point for positioning the dispensing apparatus 102. This can be particularly useful in automated processes that use a computer to control the position and orientation of the dispensing apparatus 102.

[0039] Advantageously, the dispensing of the molten composition 110 can be automated or semi-automated, thus requiring little or no intervention by a human operator. For example, the molten composition 110 can be dispensed onto the substrate 112 based on a predetermined pattern according to instructions provided by a computer. The predetermined pattern can be 2-dimensional (along a planar surface) or 3-dimensional (along a non-planar surface). The predetermined pattern can be represented by a digitized model on the computer, thereby enabling the predetermined pattern to be customized for any number of substrates.

[0040] Figure 1 The dispensing system 100 is particularly suitable for receiving a filament adhesive. A filament adhesive is a viscous substance provided in a continuous thread-like configuration. The filament adhesive preferably has a uniform cross-section.

[0041] Advantageously, the filament adhesive can be continuously fed from a spool into a dispensing apparatus, such as the dispensing apparatus.

[0042] A particularly useful filament adhesive has a core-sheath filament configuration, as described in International Patent Publication No. WO 2019 / 164678 (Nyaribo et al.). The core-sheath filament material has a configuration in which a first material (i.e., the core) is surrounded by a second material (i.e., the sheath). Preferably, the core and the sheath are concentric, sharing a common longitudinal axis. The ends of the core need not be sheathed. Advantageously, the non-viscous sheath prevents the filament adhesive 108 from adhering to itself, thereby enabling the filament adhesive 108 to be conveniently stored and handled on the spool 114.

[0043] The diameter of the core-sheath filament is not particularly limited. Factors influencing the selection of the filament diameter include size limitations on the adhesive dispenser, the desired throughput of adhesive, and the precision requirements placed on the adhesive application. The core-sheath filament can include an average diameter of 1 millimeter to 20 millimeters, 3 millimeters to 13 millimeters, 6 millimeters to 12 millimeters, or, in some embodiments, less than, equal to, or greater than 1 millimeter, 2 millimeters, 3 millimeters, 4 millimeters, 5 millimeters, 6 millimeters, 7 millimeters, 8 millimeters, 9 millimeters, 10 millimeters, 11 millimeters, 12 millimeters, 13 millimeters, 14 millimeters, 15 millimeters, 16 millimeters, 17 millimeters, 18 millimeters, 19 millimeters, or 20 millimeters. The filament adhesive 108 can be a commodity item and provided in any length suitable for application.

[0044] The dispensing methods described herein provide a number of potential technical advantages, at least some of which are unexpected. These technical advantages include: preservation of adhesive properties after dispensing, low volatile organic compound (VOC) properties, avoidance of die cutting, design flexibility, enabling complex non-planar bonding patterns, printing on thin and / or delicate substrates, and printing on irregular and / or complex topologies.

[0045] The core-sheath filament adhesives according to the present disclosure can be prepared using any known method. In exemplary embodiments, these filament adhesives are prepared by extruding a molten polymer through a coaxial die. Technical details, options, and advantages regarding the above-described core-sheath filament adhesives are described in the publication by Nyaribo et al.

[0046] It should be appreciated that the provided dispensing apparatus 102 is not necessarily limited to the dispensing system 100 shown in Figure 1 FIG. 1. In other embodiments, the dispensing apparatus 102 can have a fixed position and / or orientation. Furthermore, the dispensing apparatus 102 can accept feedstock other than filament adhesion; for example, the dispensing apparatus 102 can accept polymer pellets, flakes, or granules through a hopper or other feed mechanism known to those skilled in the art.

[0047] Figure 2 The dispensing apparatus 102 of Figure 1 is shown in greater detail. As shown, the dispensing apparatus 102 includes a barrel 120 and a rotatable screw 122 received therein. A gear box 124 and motor 126 provide a drive mechanism operably coupled to the screw 122. This drive mechanism powers the rotation of the screw 122 within the barrel 120 when the apparatus 102 is in operation. Advantageously, the motor 126 has a high torque limit, causing it to stop when a set torque level is exceeded, to avoid breakage of the screw 122 in the event of a jam during operation.

[0048] Barrel 120 contains one or more heating elements to heat the feed composition, such as a thermoplastic composition, above its melting temperature. Adjacent to one end of screw 122 is an inlet 128 where filament adhesive 108 can enter apparatus 102 and become molten due to thermal contact with the heated barrel 120 and the shearing action imparted by the rotation of screw 122 therein. On the opposite end of screw 122, barrel 120 has an outlet 129 aligned with the longitudinal axis 144 (shown) of screw 122 where the molten composition is continuously dispensed from apparatus 102. Figure 4

[0049] For proper operation, it is desirable for screw 122 to be in close engagement with the inner surface of barrel 120. There is typically a small gap therebetween to allow for the free rotation of screw 122 and to facilitate its insertion into and removal from barrel 120. During operation, this gap accommodates a small amount of molten composition, thereby providing a fluid seal against barrel 120. Further details regarding the structure and operation of screw 122 are provided below. Figure 3

[0050] Referring to Figure 3 , screw 122 is composed of a shaft 130 and a single helical thread 132 disposed thereon. Located at one end of screw 122 is a handle end 134 having a configuration capable of being mechanically coupled to a drive mechanism. At the opposite end of screw 122 is a distal end 136 (the term "distal" refers hereinafter to the direction toward distal end 136). From handle end 134 to distal end 136, the diameter of shaft 130 gradually increases. Where the outer profile of screw 122 is defined within a cylinder, as is the case here, the height of thread 132 gradually decreases as the diameter of shaft 130 increases. This has the effect of increasing the amount of shear imparted to the composition as it travels longitudinally along screw 122.

[0051] ​​To support higher total throughput, it is desirable for the screw 122 to have a relatively large channel depth (or thread depth at the shank end) to accommodate a large amount of feed flow in. Deeper channels can provide lower torque on the rotating screw. It has been found that the configuration of the screw 122 effectively distributes the composition when the channel depth is between 15% and 35%, 20% and 30%, 25% and 30% of the diameter of the screw 122 adjacent to the inlet 128 of the barrel 120, or in some embodiments, less than, equal to, or greater than 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, or 35%. The total screw diameter can be between 5 millimeters and 100 millimeters, 10 millimeters and 50 millimeters, 15 millimeters and 35 millimeters, or in some embodiments, less than, equal to, or greater than 5 millimeters, 10 millimeters, 15 millimeters, 20 millimeters, 25 millimeters, 30 millimeters, 35 millimeters, 40 millimeters, 45 millimeters, 50 millimeters, 60 millimeters, 70 millimeters, 80 millimeters, 90 millimeters, or 100 millimeters.

[0052] The thread 132 can have any suitable thread pitch, representing the distance between successive leading edges of the thread 132 measured along the longitudinal direction of the screw 122. The thread pitch can have an average thread pitch of between 40% and 80%, 50% and 70%, 60% and 70% of the screw diameter, or in some embodiments, less than, equal to, or greater than 40%, 42%, 45%, 47%, 50%, 52%, 55%, 57%, 60%, 62%, 65%, 67%, 70%, 72%, 75%, 77%, or 80%. The provided distribution screw 122 provides greater flow stability than conventional screws, enabling the use of higher pitches corresponding to higher throughput.

[0053] Advantageously, the effective operation of the screw 122 enables it to have a significantly shorter length than conventional distribution screws. The length:diameter (L:D) ratio of the screw 122 can be between 6:1 and 20:1, 8:1 and 18:1, 10:1 and 16:1, or in some embodiments, less than, equal to, or greater than 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20:1. Notably, a L:D ratio that is too high means that the screw is long, requiring a high level of torque to operate. High torque in turn requires a large motor, which consumes more energy and makes lightweighting difficult. If the L:D is too low, the screw’s function to distribute material or feed is compromised. The melt rate will be limited, so the throughput needs to be kept at a lower level.

[0054] Optionally, the screw 122 includes a plurality of gripping lugs 138 proximate to the handle end 134 of the screw 122. The gripping lugs 138 are formed by providing notches into the threads of the screw 122 and providing additional edges that help to grab the continuous filament adhesive and actively pull the continuous filament adhesive through the inlet 128 and into the barrel 120. This is a significant improvement over feed mechanisms that require the adhesive to be pushed into the feed zone, which can cause undesirable kinking and tangling of the filament adhesive.

[0055] The gripping lugs 138 can extend through 1% to 30%, 3% to 25%, 5% to 20%, or in some embodiments, less than, equal to, or greater than 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 22%, 25%, 27%, or 30% of the nominal screw length. For applications where a particulate feed is to be dispensed, the gripping lugs 138 can be omitted.

[0056] As Figure 3 Further shown, a plurality of orifices 140 or radial through-holes are present on the threads 132 of the screw 122. The orifices 140 provide communication between the outer and inner surfaces within the screw 122 during operation of the apparatus 102. The orifices 140 can have any size sufficient to enable passage of the molten composition therethrough, it being understood that the appropriate size will depend on factors such as the viscosity characteristics, temperature, and pressure of the composition. The orifices 140 can have any suitable shape, and the size can be uniform or polydisperse.

[0057] In exemplary embodiments, the orifices 140 can have an average diameter of 0.2 millimeters to 5 millimeters, 0.5 millimeters to 3 millimeters, 1 millimeter to 2.5 millimeters, or in some embodiments, less than, equal to, or greater than 0.2 millimeters, 0.3 millimeters, 0.4 millimeters, 0.5 millimeters, 0.7 millimeters, 1 millimeter, 1.5 millimeters, 2 millimeters, 2.5 millimeters, 3 millimeters, 3.5 millimeters, 4 millimeters, 4.5 millimeters, or 5 millimeters.

[0058] Figure 4 A cross-sectional view of the screw 122 reveals the inner surfaces that collectively define a cavity 142. The cavity 142 is open at the distal end 136 of the screw 122 and extends along a longitudinal axis 144 toward the handle end 134. Here, the cavity 142 has an elongated shape that is generally symmetrical about the longitudinal axis 144, although this need not be the case.

[0059] The cavity 142 terminates before reaching the shank end 134, such that the length of the cavity 142 along the longitudinal axis 144 is substantially less than the overall length of the screw 122. In some embodiments, the cavity 142 extends along less than, equal to, or greater than 20%, 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40%, 42%, 45%, 47%, 50%, 52%, 55%, 57%, 60%, 62%, 65%, 67%, or 70% of the overall length of the screw 122. These cavity dimensions advantageously efficiently draw the feed composition into the cavity 142 as it is melted, resulting in low operating torque and high throughput.

[0060] The orifice 140 is positioned along a perforated portion 146 of the cavity 142. Optionally and as shown, the perforated portion 146 has a lateral dimension that generally increases with distance from the shank end 134. This lateral dimension is not particularly limited, and can be a cross-sectional area or diameter of the cavity 142 measured perpendicular to the axis 144.

[0061] It is desirable to melt a minimum amount of the feed composition before it reaches the perforated portion 146. In some embodiments, this minimum amount can be at least 10% of the weight of the feed.

[0062] As the apparatus 102 is operated, the molten composition is transported forward by the threads 132 of the screw 122, is injected into the cavity 142 throughout the perforated portion 146, and is ultimately discharged through the outlet 129 of the barrel 120. Advantageously, the tapered shape of the cavity 142 can provide consistent forward flow of the molten composition within the cavity 142 as material continuously permeates through the orifice 140.

[0063] As Figure 4 shown, the increase in lateral (i.e., radial) dimension can occur in a discontinuous manner, where the cavity 142 is composed of a series of consecutive cylindrical segments of gradually increasing diameter. Other configurations are possible; for example, the cavity 142 can have a conical shape, where its lateral dimension continuously increases along its length. The lateral dimension of the cavity can increase linearly or can not increase linearly. More generally, the widening of the cavity 142 can not be monotonic, and can include a finite region where the lateral dimension decreases with distance from the shank end 134.

[0064] Along the outer surface of the screw 122, the orifice 140 can be characterized by an associated hole area, which is a dimensionless quantity (e.g., %) representing the total cross-sectional area of holes per unit area of the outer surface, and is a function of the number and size of the holes. As shown from Figures 2 to 4As is apparent, the number of orifices 140 along the bore 140 of the screw 122 generally increases as the distal end 136 of the screw 122 is approached. Thus, the perforated portion 146 has an increasing hole area relative to the outer surface of the screw 122 as the handle end 134 of the screw 122 is distanced.

[0065] Optionally, the hole area can be individually distributed along the length of the screw according to the melt rate of the feed composition. Having more (or larger) orifices 140 allows unmelted polymer reaching the distal end 136 of the screw 122 to enter the cavity 142 upon melting. As another option, there can be a bimodal distribution of orifices 140 based on the above to promote high melt rates.

[0066] Figure 5 Yet another cross-sectional detail of the screw 122 is shown. This figure shows the location of the orifices 140 relative to the thread 132. As shown, the thread 132 is composed of raised thread sections 150 and one or more lowered thread sections 152, each extending along the length of the thread 132. When disposed within the barrel 120, the raised thread sections 150 face the handle end 134 of the screw 122, while the lowered thread sections 152 are distal to the raised thread sections 150 and face the distal end 136 of the screw 122.

[0067] The raised thread sections 150 have a higher profile than the lowered thread sections 152. The raised thread sections 150 have a diameter that approximates the inner diameter of the barrel 120, forming a seal between the thread 132 and the inner surface of the barrel 120. The orifices 140 are at least partially located on the lowered thread sections 152 proximate this seal. During operation of the apparatus 102, a pressurized zone is created along the lowered thread sections 152 distal to the raised thread sections 150 to push the molten composition through the orifices 140 and into the cavity 142.

[0068] Advantageously, the orifices 140 are located on the surface of the thread 132 facing the barrel 120, as the feed composition within the narrow annular space surrounding the thread 132 tends to melt immediately, thereby preventing solid particles of the feed from clogging the orifices 140. Large solid particles can also be prevented from entering this annular space due to their size. While all of the orifices 140 are disposed on the lowered thread sections 152 in the present embodiment, at least some of the orifices can communicate with the cavity 142 at other locations along the screw 122. In view of the above considerations, it is preferable to locate any such orifices in locations where they are less likely to clog.

[0069] Clogging can result in a number of technical problems. For example, significant clogging of the orifices 140 can result in recirculation flow, where the residence time is increased, the feed rate is lost, the required screw torque is increased, and the pressure spikes.

[0070] It is preferred that the degree of shear experienced by the molten composition monotonically decreases as the distance from the raised thread section 150 in the distal direction increases, thereby facilitating the flow of the molten composition into the orifices 140. For Figures 2 to 5 With the screw 122 depicted in FIG. 2, a subsequent portion of the thread 132 does not reside in the distal direction of a given orifice 140 and has a height greater than the height of the lowered thread section 152. In preferred embodiments, and as shown, the lowered thread section 152 is adjacent to the exposed surface of the shaft 130. In other embodiments, at least one additional lowered thread section is located distal to the lowered thread section 152 and adjacent to the exposed surface of the shaft 130.

[0071] At its distal end 136, the screw 122 terminates in a bubble ring 154 having a diameter that approximates the inner surface diameter of the barrel 120. With the aid of a thin layer of molten composition thereon, the bubble ring 154 can form a seal against the barrel 120, thereby preventing the composition from flowing out of the bubble ring 154 between the annular groove 121 Figure 2 Since substantially all communication between the annular groove 121 and the outlet 129 is through the plurality of orifices 140, any remaining molten composition within the annular groove 121 is ultimately forced through the orifices 140 into the cavity 142.

[0072] Figures 6 to 8 A screw 222 according to an alternative embodiment is shown. The screw 222 has a configuration similar in most respects to that of the screw 122. Like the screw 122, the screw 222 has a similar handle end 234 and a distal end 236, with a single helical thread 232 extending around a shaft 230, the diameter of which generally increases from the handle end 234 to the distal end 236. As before, a plurality of orifices 240 extend radially from the outer surface of the screw 222 to an internal cavity 242.

[0073] As can be seen in Figure 6 and in the enlarged view of Figure 8 , the thread 232 of the screw 222 has a raised thread section 250 that extends continuously along the thread 232, and a plurality of lowered thread sections 252 that discontinuously diffuse along the thread 232 and are distal to the raised thread section 250. The lowered thread sections 252 have a semi-circular shape when viewed in the radial direction and extend into the raised thread section 250 to provide an opening alongside the thread channel through which molten composition from an adjacent thread channel can enter the orifices 240.

[0074] Advantages of the screw 222 include simplification of the manufacture of the screw flighting and improved sealing between the flighting 232 and the inner surface of the surrounding barrel during operation. The raised flighting segments 250 also extend over a wider area, thereby reducing the rate of wear of the screw 222 during long-term use and increasing the useful life.

[0075] Other features of the screw 222 and associated advantages are substantially similar to those described in the screw 122 and should not be repeated.

[0076] Optionally, any of the foregoing dispensing screws can include certain features or qualities not explicitly described herein. For example, the cavities within the screw can contain one or more structures that can help further improve the mixing quality in the dispensing apparatus. Such structures can include static mixers, which can or can not be configured to rotate with the screw during dispensing operations.

[0077] Methods of using the provided apparatuses include operations that can occur simultaneously during a continuous dispensing process. First is the feeding of a feed composition into the inlet of the barrel. Second is the rotation of the hollow dispensing screw to transport the composition toward the distal end of the screw. Third is the generation of sufficient pressure by the screw rotation to push the composition through the plurality of orifices and into the cavity within the screw. Fourth is the discharge of the composition from the cavity through the outlet of the barrel. These steps will be examined in greater detail below.

[0078] The feed composition is not particularly limited. In addition to the continuously fed filamentous adhesive shown in the exemplary embodiment of Figure 1 In addition to the continuously fed filamentous adhesive shown in the exemplary embodiment of

[0079] Rotation of the dispensing screw is driven by a drive mechanism and is desirably operated at a speed commensurate with the desired throughput for the dispensing operation. While dependent on the diameter of the screw, the screw speed can be from 30 rpm to 400 rpm, 50 rpm to 300 rpm, 70 rpm to 120 rpm, or in some embodiments, less than, equal to, or greater than 30 rpm, 40 rpm, 50 rpm, 60 rpm, 70 rpm, 80 rpm, 90 rpm, 100 rpm, 110 rpm, 120 rpm, 150 rpm, 170 rpm, 200 rpm, 220 rpm, 250 rpm, 270 rpm, 300 rpm, 350 rpm, or 400 rpm.

[0080] As the feed material is transported forward along the barrel, it is melted and pressurized by the incoming feed composition flowing behind it. At this pressure, the molten material flows into a plurality of orifices and into the screw cavity. The cavity is smallest near the region of the screw where melting first occurs, and as more of the solid feed composition becomes molten, the cavity gradually increases in size to accommodate the additional material. A significant benefit of this configuration is that the molten composition can be evacuated from the flighted channel shortly after formation, thereby increasing the efficiency of heat transfer to the residual unmelted composition. This in turn increases the rate of melting and enables the flighted channel depth to be gradually reduced more quickly along the length of the screw. As a result, the overall length of the screw can be reduced, thereby saving weight.

[0081] The high efficiency of the screw configuration provided enables higher throughputs. This increased throughput allows for an increased channel depth adjacent the barrel inlet to achieve higher feed rates as well as longer and more aggressive flight spacing, which can move material through the barrel more quickly than conventional dispensers. Additionally, the shorter screw reduces the overall torque, enabling a significant increase in the upper limit of the screw speed relative to conventional dispensers.

[0082] Upon entering the cavity, the molten composition is transported forward in an orderly flow profile until ultimately discharged through an outlet at the distal end of the barrel. In preferred embodiments, the flow profile is generally laminar, characterized by parallel cylindrical layers that flow between layers with minimal disruption. The trumpet shape of the cavity along its perforated portion is technically important as it helps maintain consistent flow of the composition and narrows the residence time distribution within the dispensing apparatus. Additionally, by increasing the cavity volume as it moves away from the inlet of the barrel, the pressure is reduced or maintained to allow material to flow toward the distal end. Long tails of the residence time distribution often result in poor mixing and, in some cases, thermal degradation of the composition.

[0083] The provided dispensing screws and dispensing apparatuses provide significant advantages in applications where minimization of weight and size is important. In some embodiments, the dispensing apparatus has a total weight of at most 10 kg, at most 8 kg, or at most 6 kg. The working examples of the dispensing apparatus are light and compact enough to be installed to light-weight robotic arms currently used in manufacturing facilities.

[0084] Although not exhaustive, specific exemplary embodiments are provided below:

[0085] 1. An apparatus for dispensing a composition, the apparatus comprising: a barrel having an inlet and an outlet; a screw received in the barrel, the screw having a distal end and a shank end; and a drive mechanism operably coupled to the shank end and capable of rotating the screw within the barrel, wherein the screw is hollow and comprises both an inner surface and an outer surface, the inner surface defining a cavity adjacent the outlet, and wherein the screw further comprises a plurality of apertures, the cavity and the outer surface being in communication with one another through the plurality of apertures, the plurality of apertures being positioned along a perforated portion of the cavity, and the perforated portion having a lateral dimension that increases with distance from the shank end.

[0086] 2. The apparatus of embodiment 1, wherein the screw comprises a helical thread extending around an axis, the helical thread comprising a raised thread section and one or more lowered thread sections adjacent the raised thread section, each lowered thread section being distal to the raised thread section and adjacent an exposed surface of the axis, and further wherein the plurality of apertures are at least partially located on the one or more lowered thread sections.

[0087] 3. The apparatus of embodiment 1 or 2, wherein the perforated portion has an aperture area relative to the outer surface of the screw that increases with distance from the shank end.

[0088] 4. An apparatus for dispensing a composition, the apparatus comprising: a barrel having an inlet and an outlet; a screw received in the barrel, the screw having a distal end and a shank end; and a drive mechanism operably coupled to the shank end and capable of rotating the screw within the barrel, wherein the screw is hollow and comprises both an inner surface and an outer surface, the inner surface defining a cavity adjacent the outlet, and wherein the screw further comprises a plurality of apertures, the cavity and the outer surface being in communication with one another through the plurality of apertures, and wherein the screw comprises a helical thread extending about an axis, the helical thread comprising a raised thread section and one or more lowered thread sections adjacent the raised thread section, and each lowered thread section being distal to the raised thread section and adjacent an exposed surface of the axis, and wherein the plurality of apertures are at least partially located on the one or more lowered thread sections.

[0089] 5. The apparatus of embodiment 4, wherein the plurality of apertures are positioned along a perforated portion of the cavity, the perforated portion having an increasing lateral dimension as it moves away from the shank end.

[0090] 6. The apparatus of embodiment 4 or 5, wherein the plurality of apertures are positioned along a perforated portion of the cavity, and wherein the perforated portion has an increasing aperture area relative to the outer surface of the screw as it moves away from the shank end.

[0091] 7. An apparatus for dispensing a composition, the apparatus comprising: a barrel having an inlet and an outlet; a screw received in the barrel, the screw having a distal end and a shank end; and a drive mechanism operably coupled to the shank end and capable of rotating the screw within the barrel, wherein the screw is hollow and comprises both an inner surface and an outer surface, the inner surface defining a cavity adjacent the outlet, and wherein the screw further comprises a plurality of apertures, the cavity and the outer surface being in communication with one another through the plurality of apertures, and wherein the plurality of apertures are positioned along a perforated portion of the cavity, the perforated portion having an increasing aperture area relative to the outer surface of the screw as it moves away from the shank end.

[0092] 8. The apparatus of embodiment 7, wherein the perforated portion has an increasing lateral dimension as it moves away from the shank end.

[0093] 9. The apparatus of embodiment 7 or 8, wherein the screw comprises a helical thread extending about an axis, and wherein the plurality of apertures are located on the helical thread.

[0094] 10. The apparatus of embodiment 9, wherein the helical flight comprises a raised flight section and one or more lowered flight sections adjacent to the raised flight section, and each lowered flight section is distal to the raised flight section and adjacent to an exposed surface of the shaft, and further wherein the plurality of apertures are at least partially located on the one or more lowered flight sections.

[0095] 11. The apparatus of any one of embodiments 1 to 10, wherein the outer surface of the screw and the barrel collectively define an annular groove, and wherein substantially all communication between the annular groove and the outlet is through the plurality of apertures.

[0096] 12. A screw having a distal end and a handle end for use with an apparatus for dispensing a composition, the apparatus comprising a barrel having an inlet and an outlet, and a drive mechanism operably coupled to the handle end and capable of rotating the screw within the barrel, the screw comprising: a shaft; a helical flight extending around the shaft, wherein the shaft is hollow and comprises both an inner surface and an outer surface, the inner surface defining a cavity adjacent to the outlet; and a plurality of apertures, the cavity and the outer surface being in communication with one another through the plurality of apertures, the plurality of apertures being positioned along a perforated portion of the cavity, the perforated portion having a transverse dimension that increases as it moves distally away from the handle end.

[0097] 13. A screw having a distal end and a handle end for use with an apparatus for dispensing a composition, the apparatus comprising a barrel having an inlet and an outlet, and a drive mechanism operably coupled to the handle end and capable of rotating the screw within the barrel, the screw comprising: a shaft; a helical flight extending around the shaft, wherein the shaft is hollow and comprises both an inner surface and an outer surface, the inner surface defining a cavity adjacent to the outlet; and a plurality of apertures, the cavity and the outer surface being in communication with one another through the plurality of apertures, wherein the helical flight comprises a raised flight section and one or more lowered flight sections adjacent to the raised flight section, and each lowered flight section is distal to the raised flight section and adjacent to an exposed surface of the shaft, and further wherein the plurality of apertures are at least partially located on the one or more lowered flight sections.

[0098] 14. A screw having a distal end and a handle end for use with an apparatus for dispensing a composition, the apparatus comprising a barrel having an inlet and an outlet, and a drive mechanism operably coupled to the handle end and capable of rotating the screw within the barrel, the screw comprising: a shaft; a helical thread extending around the shaft, wherein the shaft is hollow and comprises both an inner surface and an outer surface, the inner surface defining a cavity adjacent the outlet; and a plurality of apertures, the cavity and the outer surface communicating with one another through the plurality of apertures, wherein the plurality of apertures are positioned along a perforated portion of the cavity, the perforated portion having an increasing aperture area relative to the outer surface of the screw as it moves away from the handle end.

[0099] 15. A method of dispensing a composition using the apparatus of any one of embodiments 1 to 11, the method comprising: feeding the composition into the inlet of the barrel; rotating the screw to transport the composition toward the distal end of the screw and generate sufficient pressure to push the composition through the plurality of apertures and into the cavity; and expelling the composition from the cavity through the outlet of the barrel.

[0100] Example

[0101] Table 1 : Materials

[0102]

[0103] The objects and advantages of the disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof cited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

[0104] All parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, unless otherwise indicated.

[0105] Test Methods :

[0106] Material transition test: The first clear filament is fed into the dispensing head for at least three minutes to reach steady state. Dispensing is performed at 215 °C. The dispenser is stopped and the first filament is cut. A second black filament is spliced into the dispensing head. The connection between the segments relies on the inherent tackiness of the filament ends. The dispenser is run for five seconds in order to bring the second filament into the entry orifice of the barrel. Subsequently, adhesive is dispensed onto a white-painted steel plate for five seconds. The continuous measurement alternates between discarding the dispensed adhesive for five seconds and dispensing adhesive onto the white-painted steel plate for five seconds. The residence time of the second filament is monitored within the barrel. The absence or presence of the second filament exiting the nozzle is quantified using an X-Rite Color i5 brand colorimeter. The color is measured using the L*a*b* spectrum. A delta E* value of less than or equal to 3.0 is considered to not include any second filament and thus indicates the beginning or end of transition between block copolymers.

[0107] Melt mass test: Adhesive samples are dispensed onto a tempered glass substrate (50 mm x 150 mm x 6 mm) at 116 degrees Celsius. The screw is running at 200 revolutions per minute and the feed wheel is running at 13 revolutions per minute. After reaching the constant temperature of 116 degrees Celsius, the adhesive samples are dispensed for at least three minutes to reach steady state. The specimen is collected by manually moving the glass substrate under the nozzle at a rate of 25 mm / s with a gap of 6 mm to 10 mm. The nozzle is set far enough from the substrate that it does not dirty the beads, which would affect the resulting surface roughness of the adhesive. The samples are cooled for at least 30 minutes to equilibrate at room temperature. The Keyence VK-X100 laser microscope is used to quantify the surface roughness. Measurements are taken on three different locations on each sample on the diagonals of a 1.7 mm x 1.4 mm rectangle. All measurements for a given sample are averaged. An arithmetic mean deviation of the evaluated profile, Ra, value of less than 20 microns is considered to have passed the melt mass test.

[0108] Throughput measurement test: Adhesive samples are dispensed into a pre- weighed aluminum pan at 215 °C. The revolutions per minute (RPM) of the screw and feed wheel are set to a prescribed value. Dispensing is performed for one minute and the mass of the dispensed material is used to calculate the throughput in kilograms per hour (kg / h). For each set point condition, three measurements are taken and the results are averaged. Between samples, the dispenser is kept running to maintain steady state.

[0109] Preparatory Examples 1 and 2 (PE1-PE2) :

[0110] Preparation of multi-modal asymmetric block copolymer

[0111] A multi-modal, asymmetric star block copolymer (“PASBC”) was prepared according to Example 1 of U.S. Patent No. 5,393,787 (Nestegard et al.), the subject matter of which is hereby incorporated by reference in its entirety. The number average molecular weight of the polymer was about 4,000 Daltons and about 21,500 Daltons for the two end blocks, 127,000-147,000 Daltons for the arms, and about 1,100,000 Daltons for the star, as measured by SEC (size exclusion chromatography) calibrated with polystyrene standards. The polystyrene content was between 9.5 and 11.5 weight percent. The mole percent of the high molecular weight arms was estimated to be about 30%.

[0112] Preparation of core-sheath filaments

[0113] The composition of the first and second filaments is indicated in Table 2. Further description of the techniques and processes used to assemble the filament constructions are contained in PCT Patent Publication No. 2019 / 1646798 (Nyaribo et al.). The core adhesive feedstock was mixed in a 30 mm Steer twin screw dispenser operating at 212 °C. A Zenith gear pump was used to push the molten adhesive through a heated hose with an inner diameter of 25 mm and a length of 2.4 meters. The molten adhesive was dispensed through the center bore of a coaxial die into a water bath at 30 °C and manually wound into a fiber drum. The core-sheath filaments were made with a diameter of 8 mm + / - 1 mm. A 30 mm single screw dispenser set at 204 °C was used to feed the sheath material and dispense it through the outer annular bore of the coaxial die.

[0114] Table 2. Composition of filaments

[0115]

[0116] Examples 1-3 and Comparative Examples 1-3 (EX1-EX3 and CE1-CE3)

[0117] Dispensing of adhesive

[0118] The core-sheath filaments assembled in PE2 were fed directly from the fiber drum into the dispensing head. The dispensing head contained either a hollow core screw (EX1-EX3) or a non-hollow core screw (CE1-CE3), both of which were manufactured as further described below. The dispensing head was set to either 215 °C (for throughput measurements) or 116 °C (for material transition testing). The RPM of the screw and feed wheel were set to the desired rate as shown in Table 3. The sample was collected as it exited the nozzle. A nozzle with a 5 mm circular orifice and a 25 mm length was used. The results of the throughput measurements are recorded in Table 3.

[0119] Table 3. Throughput Measurement Test Results (at 215°C)

[0120]

[0121]

[0122] Example 4 (EX4) and Comparative Example 4 (CE4)

[0123] Material Transition Test

[0124] The core-sheath filaments assembled in PE1 and PE2 underwent material transformation testing. The dispensing head contained either a hollow core screw (EX4) or a non-hollow core screw (CE4). The results of the material transformation tests are recorded in Table 4. N / A indicates "Not Applicable".

[0125] Table 4. Material Transition Test Results

[0126]

[0127] Example 5 (EX5) and Comparative Example 5 (CE5)

[0128] Melt Mass Test

[0129] The core-sheath filaments assembled in PE2 underwent melt quality testing. The dispensing head contained either a hollow core screw (EX5) or a non-hollow core screw (CE5). The melt quality test results are recorded in Table 5.

[0130] Table 5. Melt Mass Test Results

[0131]

[0132] Hollow Core Screw Manufacture :

[0133] Machining in a computer numerical control (CNC) four-axis vertical end mill, such as Figure 3 and Figure 4A 22.9 cm (9.0 inch) screw with a 1.91 cm (0.75 inch) diameter was shown. Two operations were used to perform the machining process on a solid aluminum cylinder. In the first step, the outer geometry was milled, including the through hole (140). In the second step, the screw was mounted on a lathe to drill the central cavity to the appropriate depth using three different diameter drills. The pitch, i.e., the height-to-height distance between threads, was 12.5 mm, resulting in 17 turns of the thread on the screw. The screw root diameter, diameter minus thread height, was 8.9 mm. The through hole diameter was 1.6 mm. The hollow core consisted of 4 steps of increasing depth in the cavity, starting with step 1 (diameter 9.1 mm, depth 50 mm), step 2 (diameter 8.23 mm, depth 75.4 mm), step 3 (diameter 7.1 mm, depth 102 mm), and step 4 (diameter 4.1 mm, depth 128 mm). Each step in the hollow core had a corresponding frequency of through holes, which were spaced at given degrees of rotation around the screw (step 1 = 50 degrees, step 2 = 70 degrees, step 3 = 90 degrees, and step 4 = 110 degrees). The deepest section of the hollow core had the through holes spaced the furthest apart. The frequency of through holes increased, and the thread depth decreased towards the dispensing end (the end opposite the motor mount), as the amount of unmelted adhesive increased in that direction.

[0134] Non-Hollow Screw Manufacture :

[0135] A non-hollow core screw was manufactured for comparison. The design was chosen to also minimize torque and increase throughput. This was achieved with relatively deep threads. A 22.9 cm (9.0 inch) screw with a 1.91 cm (0.75 inch) diameter was machined in a computer numerical control (CNC) three-axis vertical end mill. Two operations were used to perform the machining process on a solid aluminum block. In the first step, the upper half of the screw was machined, as viewed down the axis of the screw. The partially milled block was flipped over, and then the other half of the screw was machined. The design was chosen to also minimize torque and increase throughput. This was achieved with relatively deep threads. From the motor coupling end, the first 126 mm (4.95 inches) was the same as the hollow screw design. From 126 mm to 177 mm, the screw root diameter (diameter minus thread height) increased from 8.9 mm to 13 mm. In addition, notches were included in the thread between 170 mm and 197.1 mm. This design left a relatively deep thread height, 6.1 mm, at the outlet end of the screw. This allowed for a reduction in torque and higher throughput, with an increased risk of unmelted resin passing through the dispenser.

[0136] Dispensing System Component Manufacture :

[0137] Other dispensing system components are assembled according to manufacturing techniques described in co-pending U.S. Provisional Patent Application No. 62 / 810248 (Napierala et al.).

[0138] All cited references, patents and patent applications referenced in the above granted applications are hereby incorporated by reference in their entirety. In the event of inconsistencies between the incorporated references and the present application, the information in the foregoing specification shall prevail.

[0139] The foregoing description of the present disclosure is not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed. While specific embodiments of, and examples for, the present disclosure are described herein for illustrative purposes, various equivalent alterations and modifications will be apparent to others skilled in the art and fall within the scope of the present disclosure. Accordingly, the scope of the present disclosure is to be limited not by the foregoing description, but only by the following claims, and all changes and modifications that come within the meaning and range of equivalents of the claims.

Claims

1. An apparatus for dispensing a composition, the apparatus comprising: a barrel having an inlet and an outlet; a screw received in the barrel, the screw having a distal end and a handle end, and having a shaft having a single helical thread disposed thereon; and a drive mechanism operably coupled to the handle end and capable of rotating the screw within the barrel, wherein the screw is hollow and includes both an inner surface and an outer surface, the inner surface defining a cavity adjacent the outlet, and wherein the screw further includes a plurality of apertures, the cavity and the outer surface being in communication with one another through the plurality of apertures, the plurality of apertures being positioned along a perforated portion of the cavity, the perforated portion having a lateral dimension that increases with distance from the handle end, and the plurality of apertures being located on the helical thread, wherein the perforated portion defines an aperture area that increases with distance from the handle end, the aperture area representing a total cross-sectional area of the apertures per unit area of the one or more outer surfaces, and a diameter of the shaft gradually increasing from the handle end to the distal end.

2. The apparatus of claim 1, wherein the screw includes the helical thread extending around the shaft, the helical thread including a raised thread section and one or more lowered thread sections adjacent the raised thread section, each lowered thread section being distal to the raised thread section and adjacent an exposed surface of the shaft, and further wherein the plurality of apertures are at least partially located on the one or more lowered thread sections.

3. An apparatus for dispensing a composition, the apparatus comprising: a barrel having an inlet and an outlet; a screw received in the barrel, the screw having a distal end and a handle end, and having a shaft having a single helical thread disposed thereon; and a drive mechanism operably coupled to the handle end and capable of rotating the screw within the barrel, wherein the screw is hollow and includes both an inner surface and an outer surface, the inner surface defining a cavity adjacent the outlet, and wherein the screw further includes a plurality of apertures, the cavity and the outer surface being in communication with one another through the plurality of apertures, and wherein the screw includes the helical thread extending around the shaft, the helical thread including a raised thread section and one or more lowered thread sections adjacent the raised thread section, and each lowered thread section being distal to the raised thread section and adjacent an exposed surface of the shaft, and wherein the plurality of apertures are located on the helical thread, and at least partially located on the one or more lowered thread sections, wherein the plurality of apertures are characterized by an aperture area that increases with distance from the handle end, the aperture area representing a total cross-sectional area of the apertures per unit area of the one or more outer surfaces, and a diameter of the shaft gradually increasing from the handle end to the distal end.

4. The apparatus of claim 3, wherein the plurality of apertures are positioned along a perforated portion of the cavity, the perforated portion having a lateral dimension that increases with distance from the handle end.

5. The device of claim 3, wherein the plurality of orifices are positioned along a perforated portion of the cavity, and wherein the perforated portion has an area relative to the outer surface of the screw that increases with distance from the shank end.

6. The device of claim 4, wherein the plurality of orifices are positioned along a perforated portion of the cavity, and wherein the perforated portion has an area relative to the outer surface of the screw that increases with distance from the shank end.

7. An apparatus for dispensing a composition, the apparatus comprising: A feed cylinder having an inlet and an outlet; A screw, which is received in the barrel, has a distal end and a shank end, and has a shaft having a single helical thread thereon; and A drive mechanism, operably coupled to the shank end and capable of rotating the screw within the barrel, The screw is hollow and includes both an inner surface and an outer surface, the inner surface defining a cavity adjacent to the outlet, and wherein... The screw also includes multiple orifices, through which the cavity and the outer surface communicate with each other, and The plurality of orifices are positioned along a perforated portion of the cavity, the perforated portion having a hole area that increases with distance from the shank end relative to the outer surface of the screw, and the plurality of orifices are located on the helical thread, and the diameter of the shaft gradually increases from the shank end to the distal end.

8. The device of claim 7, wherein the perforated portion has a lateral dimension that increases with distance from the handle end.

9. The device of claim 7, wherein the screw includes the helical thread extending about the shaft.

10. The device of claim 9, wherein the helical thread comprises a raised thread section and one or more lowered thread sections adjacent to the raised thread section, and each lowered thread section is located distal to the raised thread section and adjacent to an exposed surface of the shaft, and further wherein the plurality of orifices are at least partially located on the one or more lowered thread sections.

11. The device according to any one of claims 1 to 10, wherein the outer surface of the screw and the barrel together define an annular groove, and wherein substantially all communication between the annular groove and the outlet is through the plurality of orifices.

12. A screw having a distal end and a shank end for use with a device for dispensing a composition, the device including a barrel and a drive mechanism, the barrel having an inlet and an outlet, the drive mechanism being operably coupled to the shank end and capable of rotating the screw within the barrel, the screw comprising: A shaft having a single helical thread disposed thereon; The helical thread extends around the shaft, wherein the shaft is hollow and includes both an inner surface and an outer surface, the inner surface defining a cavity adjacent to the outlet; and a plurality of apertures through which the cavity and the outer surface are in communication with one another, the plurality of apertures being positioned along a perforated portion of the cavity, the perforated portion having a transverse dimension that increases as it moves away from the shank end, and the plurality of apertures being located on the helical thread, wherein the plurality of apertures are characterized by an aperture area that increases as it moves away from the shank end, the aperture area representing a total cross-sectional area of the apertures per unit area of the one or more outer surfaces.

13. A screw having a distal end and a shank end for use with an apparatus for dispensing a composition, the apparatus comprising a barrel having an inlet and an outlet, and a drive mechanism operably coupled to the shank end and capable of rotating the screw within the barrel, the screw comprising: a shaft having a single helical thread disposed thereon; the helical thread extending around the shaft, wherein the shaft is hollow and comprises both an inner surface and an outer surface, the inner surface defining a cavity adjacent to the outlet; and a plurality of apertures through which the cavity and the outer surface are in communication with one another, wherein the helical thread comprises a raised thread section and one or more lowered thread sections adjacent to the raised thread section, and each lowered thread section is distal to the raised thread section and adjacent to an exposed surface of the shaft, further wherein the plurality of apertures are located on the helical thread and at least partially on the one or more lowered thread sections, wherein the plurality of apertures are characterized by an aperture area that increases as it moves away from the shank end, the aperture area representing a total cross-sectional area of the apertures per unit area of the one or more outer surfaces, and the diameter of the shaft gradually increases from the shank end to the distal end.

14. A screw having a distal end and a shank end for use with an apparatus for dispensing a composition, the apparatus comprising a barrel having an inlet and an outlet, and a drive mechanism operably coupled to the shank end and capable of rotating the screw within the barrel, the screw comprising: a shaft having a single helical thread disposed thereon; the helical thread extending around the shaft, wherein the shaft is hollow and comprises both an inner surface and an outer surface, the inner surface defining a cavity adjacent to the outlet; and a plurality of apertures through which the cavity and the outer surface are in communication with one another, wherein the plurality of apertures are positioned along a perforated portion of the cavity, the perforated portion having an aperture area that increases as it moves away from the shank end relative to the outer surface of the screw, and the plurality of apertures are located on the helical thread, and the diameter of the shaft gradually increases from the shank end to the distal end.

15. A method of dispensing a composition using the apparatus of any one of claims 1 to 11, the method comprising: feeding the composition into the inlet of the barrel; rotating the screw to transport the composition toward the distal end of the screw and generate sufficient pressure to push the composition through the plurality of orifices and into the cavity; and discharging the composition from the cavity through the outlet of the barrel.

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