Coextruded polymeric articles (including layers) having projections are known in the art. For example, it is known to provide a co-extruded, layer structures where the layer is partitioned, not as coextensive layers in the thickness direction, but as stripes or segments along the width dimension of the layer. This has sometimes been called “side-by-side” co-extrusion.
There is a desire for additional polymeric articles with projections that offer different configurations and/or properties (e.g., adhesive properties) over conventional articles. Some adhesive systems that switch from a state of relatively low or no adhesion to a state of much higher adhesion upon application of a certain trigger (commonly called “adhesion on demand” systems) are known. Many of these systems use triggers such as solvents, ultra violet light, heat, or magnetic forces, to create tiered adhesive performance once or repetitively. These systems are limited in applications for several reasons. For many of these triggers, the adhesive system must contain specific chemical groups, which restricts usage to applications where those chemical groups can be tolerated. These systems can be used only where a particular trigger is available and can be effectively applied to the adhesive system. Further, some triggers are difficult or inconvenient for consumers to use. Certain triggers, as well as the chemical groups in the adhesive that respond to such triggers, can be cost-prohibitive.
There is a continuing desire for new coextruded polymeric article constructions. Further, there is a need for “adhesion on demand” systems where the trigger is applicable to all adhesive chemistries, the trigger is more broadly or even universally available, the trigger is easy to apply, not only industrially, but by a consumer, and the adhesion-on-demand system is not exceedingly expensive.
In one aspect, the present disclosure describes a coextruded polymeric netting having a machine direction comprising:
a plurality of pairs (in some embodiments, at least 3, 4, 5, 10, 25, 50, 100, 250, 500, 750, or even at least 1000 pairs) of:
In some embodiments, the first segment has first and second opposed major surfaces, wherein the second segment extends past both the first and second surfaces of the first segment, and wherein the third material is on at least one of the first or second major surfaces (in some embodiments, on both the first and second major surfaces) of the second segment both above and below the first segment.
In another aspect, the present disclosure describes a method of making a coextruded polymeric netting described herein, the method comprising:
providing an extrusion die comprising of at least three cavities, a dispensing surface, and fluid passageways between the at least three cavities and the dispensing surface, wherein the dispensing surface has an array of first dispensing orifices separated by an array of second dispensing orifices, wherein the first and second dispensing orifices each have a height and a width, and wherein the height of the second dispensing orifices is at least two times larger than the height of the first dispensing orifices, and wherein the second dispensing orifices comprises a first plurality of a repeating sequence of shims that together provide a fluid passageway between the third cavity and the third orifice, a second plurality of shims that provides a spacer section, and a third plurality of a repeating sequence of shims that together provide a fluid passageway between the second cavity and a second orifice and;
dispensing polymeric ribbons from the second dispensing orifices at a first speed while simultaneously dispensing polymeric segments from the first dispensing orifices at a second speed to provide the polymeric netting, wherein the second speed is at least twice the first speed.
Netting described herein are useful, for example, in fastener systems (e.g., a fastener system comprising at least one netting described herein).
In another aspect, the present disclosure describes an article comprising first and second coextruded polymeric nettings described herein, wherein a portion of some of the first segments of the first coextruded polymeric netting are engaged between some adjacent first segments of the second coextruded polymeric netting. In some embodiments, the engaged first and second coextruded polymeric nettings are the same netting.
Netting described herein are useful, for example, for tape landing zones (e.g., in medical applications where the netting is wrapped around an appendage and attached to itself to provide a medical tape landing zone without adhesion to skin), bundling applications where it is desired to maintain breathability without an air tight barrier such as what happens with elastomeric thin film wraps, and bundling applications where it is desired to have compression wrap without adhesion to the wrapped substrate.
Referring to
Referring to
“Bond regions” as used herein refers to a line of demarcation between two segments bonded together. A demarcation line or boundary region can be detected as described in the Example using Differential Scanning calorimetry (DSC). Comparing by temperature modulated differential scanning calorimetry a region containing mostly a demarcation line (e.g., in
In some embodiments, there is a demarcation line between the third material and the second material of the second segments.
In some embodiments, the first and second materials are at least one of a thermoplastic resin (e.g., at least one of, including copolymers and blends thereof, a polyolefin (e.g., polypropylene and polyethylene), a polyvinyl chloride, a polystyrene, a nylon, a polyester (e.g., polyethylene terephthalate) or an elastomer (e.g., an ABA block copolymer, a polyurethane, a polyolefin elastomer, a polyurethane elastomer, a metallocene polyolefin elastomer, a polyamide elastomer, an ethylene vinyl acetate elastomer, and a polyester elastomer)). When articles described herein are used in medical applications (e.g., as a wrap around an appendage), it can be desirable for the article to be sufficiently transparent or translucent to view or generally view the skin under the wrap). Materials that may provide such transparent or translucent articles include thermoplastic elastomers that are essentially non-crystalline (e.g., ethylene vinyl acetate copolymers, polyurethane, polyolefin copolymers, and styrenic block copolymers).
In some embodiments, the segments are within the same plane.
In some embodiments, each second segment has a height extending from the first major surface of the adjacent first segment to the distal end of that second segment, wherein the third material extends up to 50 (in some embodiments, up to 60, 70, 75, 80, 85, 90, or even up to 95) percent of the height of that second segment from the first major surface of the first segment toward the distal end.
In some embodiments, the third material is also on the first major surface of the first segment between second segments.
In some embodiments, a portion of the first major surface of the first segment between second segments is free of adhesive.
In some embodiments, each second segment has a height extending from the first major surface of the adjacent first segment to the distal end of that second segment, wherein adjacent pairs of second segments in a repeating pattern have different heights, wherein a second segment having its major surface free of adhesive is shorter (in some embodiments, at least 10, 20, 25, 30, 40, 50, 60, 70, 75, or even at least 80 percent shorter) than the second segment in the pair having the adhesive on the major surfaces of its side.
In some embodiments, the second segments are generally parallel to each other and generally perpendicular to the first major surface of the adjacent first segments.
In some embodiments, the first segments comprise first material, the second segments comprise second material, and the adhesive comprises third material, wherein the first and second are the same material and different from the third material.
In some embodiments, the first segments comprise first material, the second segments comprise second material, and the adhesive comprises third material, wherein the first, second, and third materials are different from each other.
In some embodiments, the second segments have a height from the first major surface of the adjacent segment to the distal ends of the second segments are in a range from 0.05 to 5 (in some embodiments, in a range from 0.1 to 2, or even 0.1 to 1) mm.
In some embodiments, the second segments have a longest cross-sectional dimension in a range from 0.05 to 0.5 (in some embodiments, in a range from 0.05 to 0.2, or even 0.05 to 0.1) mm.
In some embodiments, the second segments have an aspect ratio (i.e., height from the first major surface of the adjacent first segment to width) of at least 1.5:1 (in some embodiments, at least 2:1, 3:1, or even at least 4:1).
In some embodiments, the first segments are spaced apart not more than 5 mm (in some embodiments, not more than 1 mm).
In some embodiments, there is a distance between the first and second major surfaces of the first segments in a range from 0.025 mm to 1 mm (in some embodiments, in a range from 0.025 mm to 0.5 mm, 0.025 mm to 0.2 mm, or even 0.025 mm to 0.1 mm).
In some embodiments, there are at least 2.5 (in some embodiments, at least 5, 10, 15, 20, 25, 30, 35, or even up to 40) second segments per cm.
In some embodiments, the third material has a thickness in a range from 0.001 to 0.25 (in some embodiments in a range from, 0.001 to 0.1, 0.001 to 0.05, 0.001 to 0.025, or even 0.001 to 0.01) mm.
In some embodiments, the third material is adhesive. In some embodiments, the adhesive is at least one of an acrylate copolymer pressure sensitive adhesive, a rubber-based adhesive (e.g., those based on at least one of natural rubber, polyisobutylene, polybutadiene, butyl rubber, or styrene block copolymer rubber), a silicone polyurea-based adhesive, a silicone polyoxamide-based adhesive, a polyurethane-based adhesive, or a poly(vinyl ethyl ether)-based adhesive. In some embodiments, the styrene block copolymer rubber is of the form as described in the U.S. Pat. No. 5,296,547 (Nestegard et al.) and U.S. Pat. No. 5,393,787 (Nestegard et al.).
In some embodiments, the adhesive is on at least one of the first and second major surfaces of each second segment.
In some embodiments, a portion of the major surface adjacent to the respective distal end of the second segments are free of the adhesive.
In some embodiments, the distal ends of at least some (in some embodiments, all) of the second segments are free of adhesive.
In another aspect, the present disclosure describes a method of making a coextruded polymeric netting described herein, the method comprising:
providing an extrusion die comprising of at least three cavities, a dispensing surface, and fluid passageways between the at least three cavities and the dispensing surface, wherein the dispensing surface has an array of first dispensing orifices separated by an array of second dispensing orifices, wherein the first and second dispensing orifices each have a height and a width, wherein the height of the second dispensing orifices is at least two times larger than the height of the first dispensing orifices, and wherein the second dispensing orifices comprises a first plurality of a repeating sequence of shims that together provide a fluid passageway between the third cavity and the third orifice, a second plurality of shims that provides a spacer section, and a third plurality of a repeating sequence of shims that together provide a fluid passageway between the second cavity and a second orifice; and
dispensing polymeric ribbons from the second dispensing orifices at a first speed while simultaneously dispensing polymeric segments from the first dispensing orifices at a second speed to provide the polymeric netting, wherein the second speed is at least twice the first speed.
Coextruded polymeric articles described herein (including that shown in
Referring again to
In some embodiments, the shims will be assembled according to a plan that provides a sequence of shims of diverse types. Since different applications may have different requirements, the sequences can have diverse numbers of shims. The sequence may be a repeating sequence that is not limited to a particular number of repeats in a particular zone. Or the sequence may not regularly repeat, but different sequences of shims may be used. The shape of the passageways within, for example, a sequence of shims, may be identical or different. Examples of passageway cross-sectional shapes include round, square, and rectangular shapes. In some embodiments, the shims that provide a passageway between one cavity and the dispensing slot might have a flow restriction compared to the shims that provide a passageway between another cavity and the dispensing slot. The width of the distal opening within, for example, a different sequence of shims, may be identical or different. For example, the portion of the distal opening provided by the shims that provide a passageway between one cavity and the dispensing orifice could be narrower than the portion of the distal opening provided by the shims that provide a passageway between another cavity and the dispensing orifice. In general, the distal opening to create the second segments is much longer than the distal opening to create the first segment.
Individual cavities and passageways provide a conduit for polymer to orifices to create the segments and third material portions. First segments are formed from the first segment plurality of orifices. Second segments are formed from the second segment plurality of orifices. First and second segments weld together after the die exit, to form intermittently bonded netting. Individual flow streams of the second and third material merge together in the second segment orifice to form a continuous, solid second segment. The second dispensing orifices create demarcation lines between the second material and the third material. A gap between the first and second dispensing orifices enables the intermittent bonding between first and second segments immediately at the exit of the die.
In some embodiments, extrusion dies described herein include a pair of end blocks for supporting the plurality of shims. In these embodiments, it may be convenient for one, or even all, of the shims to each have at least one through-holes for the passage of connectors between the pair of end blocks. Bolts disposed within such through-holes are one convenient approach for assembling the shims to the end blocks, although the ordinary artisan may perceive other alternatives for assembling the extrusion die. In some embodiments, the at least one end block has an inlet port for introduction of fluid material into one, or more, of the cavities.
In some embodiments, the shims will be assembled according to a plan that provides a repeating sequence of shims of diverse types. The repeating sequence can have diverse numbers of shims per repeat. For a first example, a repeating sequence comprised of five different shims is described below to create the orifice pattern shown in
In some embodiments, the assembled shims (conveniently bolted between the end blocks) further comprise a manifold body for supporting the shims. The manifold body has at least one (e.g., in some embodiments, at least two three, four, or more) manifold therein, the manifold having an outlet. An expansion seal (e.g., made of copper or alloys thereof) is disposed to seal the manifold body and the shims, such that the expansion seal defines a portion of at least one of the cavities (in some embodiments, a portion of both the first and second cavities), and such that the expansion seal allows a conduit between the manifold and the cavity.
Typically, the passageway between cavity and dispensing orifice is up to 25 mm in length. Sometimes the fluid passageways leading to one array has greater fluid restriction than the fluid passageways leading to at least one of the other arrays. Typically, the combined length of passageway of the second and third material is up to 5 mm. The combined passageway may need to be shortened, and in some embodiments eliminated, dependent upon the viscosity ratio of the second and third materials.
The shims for dies described herein typically have thicknesses in the range from 50 micrometers to 125 micrometers, although thicknesses outside of this range may also be useful. Typically, the fluid passageways have thicknesses in a range from 50 micrometers to 750 micrometers, and lengths less than 25 mm (with generally a preference for smaller lengths for decreasingly smaller passageway thicknesses), although thicknesses and lengths outside of these ranges may also be useful. For large diameter fluid passageways, several smaller thickness shims may be stacked together, or single shims of the desired passageway width may be used.
The shims are tightly compressed to prevent gaps between the shims and polymer leakage. For example, 12 mm (0.5 inch) diameter bolts are typically used and tightened, at the extrusion temperature, to their recommended torque rating. Also, the shims are aligned to provide uniform extrusion out the extrusion orifice, as misalignment can lead to segments extruding at an angle out of the die which inhibits desired bonding of the net. To aid in alignment, an alignment key can be cut into the shims. Also, a vibrating table can be useful to provide a smooth surface alignment of the extrusion tip.
In practicing methods described herein, the polymeric materials might be solidified simply by cooling. This can be conveniently accomplished passively by ambient air, or actively, for example, by quenching the extruded first and second polymeric materials on a chilled surface (e.g., a chilled roll). In some embodiments, any of the first, second, third or fourth polymeric materials are low molecular weight polymers that need to be cross-linked to be solidified, which can be done, for example, by electromagnetic or particle radiation. In some embodiments, it is desirable to maximize the quenching time to increase the bond strength.
Referring now to
Shim 500 has several holes 547 to allow the passage of, for example, bolts, to hold shim 500 and others to be described below into an assembly. Shim 500 also has dispensing surface 562, and in this embodiment, dispensing surface 562 has indexing groove 586 which can receive an appropriately shaped key to ease assembling diverse shims into a die. This embodiment has shoulders 590 and 592 which can assist in mounting the assembled die with a mount of the type shown in
Referring now to
Shim 600 has several holes 647 to allow the passage of, for example, bolts, to hold shim 600 and others to be described below into an assembly. Shim 600 also has dispensing surface 662, and in this embodiment, dispensing surface 662 has indexing groove 686 which can receive an appropriately shaped key to ease assembling diverse shims into a die. The shim may also have identification notch 682 to help verify that the die has been assembled in the desired manner. This embodiment has shoulders 690 and 692 which can assist in mounting the assembled die with a mount of the type shown in
Referring now to
Shim 700 has several holes 747 to allow the passage of, for example, bolts, to hold shim 700 and others to be described below into an assembly. Shim 700 also has dispensing surface 762, and in this embodiment, dispensing surface 762 has indexing groove 786 which can receive an appropriately shaped key to ease assembling diverse shims into a die. The shim may also have identification notch 782 to help verify that the die has been assembled in the desired manner. This embodiment has shoulders 790 and 792 which can assist in mounting the assembled die with a mount of the type shown in
Referring to
Shim 800 has several holes 847 to allow the passage of, for example, bolts, to hold shim 800 and others to be described below into an assembly. Shim 800 also has dispensing surface 862, and in this embodiment, dispensing surface 862 has indexing groove 886 which can receive an appropriately shaped key to ease assembling diverse shims into a die. The shim may also have identification notch 882 to help verify that the die has been assembled in the desired manner. This embodiment has shoulders 890 and 892 which can assist in mounting the assembled die with a mount of the type shown in
Referring to
Shim 900 has several holes 947 to allow the passage of, for example, bolts, to hold shim 900 and others to be described below into an assembly. Shim 900 also has dispensing surface 962, and in this embodiment, dispensing surface 962 has indexing groove 986 which can receive an appropriately shaped key to ease assembling diverse shims into a die. The shim may also have identification notch 982 to help verify that the die has been assembled in the desired manner. This embodiment has shoulders 990 and 992 which can assist in mounting the assembled die with a mount of the type shown in
Referring to
Shim 1000 has several holes 1047 to allow the passage of, for example, bolts, to hold shim 1000 and others to be described below into an assembly. Shim 1000 also has dispensing surface 1062, and in this embodiment, dispensing surface 1062 has indexing groove 1086 which can receive an appropriately shaped key to ease assembling diverse shims into a die. The shim may also have identification notch 1082 to help verify that the die has been assembled in the desired manner. This embodiment has shoulders 1090 and 1092 which can assist in mounting the assembled die with a mount of the type shown in
Referring to
Referring to
Referring to
In this embodiment, inlet fittings 1350a, 1350b, 1350c, and a fourth fitting not shown provide a flow path for four streams of molten polymer through end blocks 1344a and 1344b to cavities 562a, 562b, and 562c, and 562d. Compression blocks 1304 have notch 1306 that conveniently engages the shoulders on shims (e.g., 590 and 592) on 500. When mount 1300 is completely assembled, compression blocks 1304 are attached by, for example, machine bolts to backplates 1308. Holes are conveniently provided in the assembly for the insertion of cartridge heaters 52.
Referring to
Typically, the polymeric segments are extruded in the direction of gravity. This enables collinear segments to collide with each other before becoming out of alignment with each other. In some embodiments, it is desirable to extrude the segments horizontally, especially when the extrusion orifices of the first and second polymer are not collinear with each other.
In practicing methods described herein, the polymeric materials might be solidified simply by cooling. This can be conveniently accomplished passively by ambient air, or actively by, for example, quenching the extruded first and second polymeric materials on a chilled surface (e.g., a chilled roll). In some embodiments, the first and/or second polymeric materials are low molecular weight polymers that need to be cross-linked to be solidified, which can be done, for example, by electromagnetic or particle radiation. In some embodiments, it is desirable to maximize the time to quenching to increase the bond strength.
Optionally, it may be desirable to stretch the as-made netting. Stretching may orientate the segments and has been observed to increase the tensile strength properties of the netting. Stretching may also reduce the overall segment size, which may be desirable for applications which benefit from a relatively low basis weight. As an additional example, if the materials and the degree of stretch, are chosen correctly, the stretch can cause some of the segments to yield while others do not, tending to form loft (e.g., the loft may be created because of the length difference between adjacent bonded netting segments or by curling of the bonds due to the yield properties of the segments forming the bond). The attribute can be useful for packaging applications where the material can be shipped to package assembly in a relatively dense form, and then lofted, on location.
Portions of the exteriors of the first and second segments bond together at the bond regions. In methods described herein for making nettings described herein, the bonding occurs in a relatively short period of time (typically less than 1 second). The bonds are formed from continuous molten segments as they exit the die. The bonds are formed, parallel to each other and parallel to the machine direction of the netting. The bond regions, as well as the segments typically cool through air and natural convection and/or radiation. In selecting polymers for the segments, in some embodiments, it may be desirable to select polymers of bonding segments that have dipole interactions (or H-bonds) or covalent bonds. Bonding between segments has been observed to be improved by increasing the time that the segments are molten to enable more interaction between polymers. Bonding of polymers has generally been observed to be improved by reducing the molecular weight of at least one polymer and or introducing an additional co-monomer to improve polymer interaction and/or reduce the rate or amount of crystallization. In some embodiments, the bond strength is greater than the strength of the segments forming the bond. In some embodiments, it may be desirable for the bonds to break and thus the bonds will be weaker than the segments.
In some embodiments, polymeric materials used to make coextruded polymeric articles described herein may comprise a colorant (e.g., pigment and/or dye) for functional (e.g., optical effects) and/or aesthetic purposes (e.g., each has different color/shade). Suitable colorants are those known in the art for use in various polymeric materials. Exemplary colors imparted by the colorant include white, black, red, pink, orange, yellow, green, aqua, purple, and blue. In some embodiments, it is desirable level to have a certain degree of opacity for one or more of the polymeric materials. The amount of colorant(s) to be used in specific embodiments can be readily determined by those skilled in the (e.g., to achieve desired color, tone, opacity, transmissivity, etc.). If desired, the polymeric materials may be formulated to have the same or different colors.
Netting described herein are useful, for example, in fastener systems (e.g., a fastener system comprising at least one netting described herein).
Another exemplary use for coextruded polymeric articles described herein is to make an article comprising first and second coextruded polymeric nettings described herein, wherein a portion of some of the first segments of the first coextruded polymeric netting are engaged between some of the adjacent first segments of the second coextruded polymeric netting. In some embodiments, the engaged first and second coextruded polymeric nettings are the same netting. Referring to
Netting described herein are useful, for example, for tape landing zones (e.g., in medical applications where the netting is wrapped around an appendage and attached to itself to provide a medical tape landing zone without adhesion to skin), bundling applications where it is desired to maintain breathability without an air tight barrier such as what happens with elastomeric thin film wraps (i.e., the netting construction of the articles described herein facilitates the breathability of the article), and bundling applications where it is desired to have compression wrap without adhesion to the wrapped substrate.
1A. A coextruded polymeric netting having a machine direction comprising:
a plurality of pairs (in some embodiments, at least 3, 4, 5, 10, 25, 50, 100, 250, 500, 750, or even at least 1000 pairs) of:
providing an extrusion die comprising of at least three cavities, a dispensing surface, and fluid passageways between the at least three cavities and the dispensing surface, wherein the dispensing surface has an array of first dispensing orifices separated by an array of second dispensing orifices, wherein the first and second dispensing orifices each have a height and a width, wherein the second dispensing orifices each have a height to width aspect ratio of at least two to one, and wherein the height of the second dispensing orifices is at least two times larger than the height of the first dispensing orifices, and wherein the second dispensing orifices comprises a first plurality of a repeating sequence of shims that together provide a fluid passageway between the third cavity and the third orifice, a second plurality of shims that provides a spacer section, and a third plurality of a repeating sequence of shims that together provide a fluid passageway between the second cavity and a second orifice and;
dispensing polymeric ribbons from the second dispensing orifices at a first speed while simultaneously dispensing polymeric segments from the first dispensing orifices at a second speed to provide the polymeric netting, wherein the second speed is at least twice the first speed.
1C. A fastener system comprising any preceding A Exemplary Embodiment coextruded polymeric netting.
1D. A fastener system comprising two of any preceding A Exemplary Embodiment coextruded polymeric nettings.
1E. An article comprising first and second coextruded polymeric nettings of any preceding A Exemplary Embodiment, wherein a portion of some of the second segments of the first coextruded polymeric netting are engaged between some of the adjacent second segments of the second coextruded polymeric netting.
2E. The article of Exemplary Embodiment 1E, wherein the engaged first coextruded and second polymeric nettings are the same netting.
Advantages and embodiments of this invention are further illustrated by the following example, but the particular materials and amounts thereof recited in this example, as well as other conditions and details, should not be construed to unduly limit this invention. All parts and percentages are by weight unless otherwise indicated.
A co-extrusion die as generally depicted in
The inlet fittings on the two end blocks were each connected to three conventional single-screw extruders. The extruders feeding two cavities were loaded with polyethylene copolymer (obtained under the trade designation “ELVALOY 12024” from DuPont Company, Wilmington, Del.). The polyethylene for the first cavity, the second segment, was dry blended with 3 wt. % red color concentrate (obtained under the trade designation “PP33643730” from Clariant Corporation, Minneapolis, Minn.). The polyethylene for the second cavity, the third material, was dry blended with 3 wt. % blue color concentrate (obtained under the trade designation “PP554643692” from Clariant Corporation). The polyethylene for the third cavity, the first segment, was dry blended with 3 wt. % white color concentrate (obtained under the trade designation “PP1015100S” from Clariant Corporation). The fourth cavity was not used.
The melt was extruded vertically into an extrusion quench takeaway. The quench roll was a smooth temperature-controlled chrome plated 20 cm diameter steel roll. The quench temperature was controlled with internal water flow. The web path wrapped 180 degrees around the chrome steel roll and then to a windup roll. Under these conditions a polymeric layer was produced as generally depicted in
Other process conditions are listed below:
An optical microscope was used to measure the web profile. A digital optical image of the Example is shown in
Foreseeable modifications and alterations of this disclosure will be apparent to those skilled in the art without departing from the scope and spirit of this invention. This invention should not be restricted to the embodiments that are set forth in this application for illustrative purposes.
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/IB2020/051800 | 3/3/2020 | WO | 00 |
Number | Date | Country | |
---|---|---|---|
62816283 | Mar 2019 | US |